baltic gas final scientific report · final scientific report reporting period: january 1, 2009 –...

BALTIC GAS Final scientific report

Reporting period:

January 1, 2009 – December 31, 2011

Report compiled and edited by Bo Barker Jørgensen and Henrik Fossing

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Table of content

page

1. Executive summary 3

1.1 BALTIC GAS main results 3

1.2 Project management, research cruises, and data collection 5

1.3 Methane gas and seismo-acoustic mapping 8

1.3.1 Spatial mapping of shallow gas using a low frequency multibeam echosounder 9

1.3.2 Towards quantification of shallow free gas in Baltic Sea sediments 10

1.3.3 Rising of methane gas bubbles through the water column and pockmark distribution in

the Gdansk Basin

13

1.4 Sediment and water column biogeochemistry and physical characters 15

1.4.1 Methane in Baltic Sea sediments 16

1.4.2 Holocene mud deposits and presence of free methane gas (an example from Aarhus Bay) 19

1.4.3 Distribution and temporal variability of dissolved methane in the water column of the

Baltic Sea

20

1.4.4 Continuous measurement of surface methane concentrations – ships of opportunity 22

1.4.5 The role of the inshore and littoral region for methane emissions from the Baltic Sea 24

1.5 Modelling methane dynamics in the Baltic Sea 26

1.5.1 Climate-related effects on past and future methane dynamics 26

1.5.1.1 Hindcasting methane dynamics during the Holocene 26

1.5.1.2 Forecasting the impact of climate change on methane gas inventories 27

1.5.2 Environmental controls of gaseous methane production in the Baltic Sea (an example

from Aarhus Bay)

28

1.5.3 Regionalization and budgeting of methane cycle 29

1.6 Deliverables 31

2. Further research and exploitation of the results 33

2.1. Further research 33

2.2. Exploitation of the results 34

3. Work package overview 36

WP 1: Project management, coordination and dissemination 36

WP 2: Data mining and GIS-mapping 37

WP 3: Gas and seismo-acoustic mapping 40

WP 4: Biogeochemistry 43

WP 5: Modelling and data integration 49

4. BALTIC GAS Science team 53

5. Educational activities 55

6. Stakeholder events and other related activities 57

6.1 Stakeholder and scientific committees 57

6.2 Other related activities 59

7. Meetings and conferences 60

8. Peer reviewed scientific papers 63

9. Submitted scientific papers 64

10. Statistics for the performance assessment of the Programme 64

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1. Executive Summary

BALTIC GAS is a research project funded by BONUS (i.e The Baltic Organisations Network for funding Science)

that addresses methane in the Baltic Sea and its mutual coupling to climate change and eutrophication. Through

application of seismo-acoustic techniques and geochemical approaches BALTIC GAS mapped shallow gas in the

Baltic Sea seabed and water column and analysed methane production, consumption, gas accumulation, and

methane fluxes for a better understanding and quantitative synthesis of the dynamics and budget of methane in

Baltic Sea.

The BALTIC GAS research project brought together a multidisciplinary team of scientists from 12 research institu-

tions (see 4. BALTIC GAS Science team) with the goal to (1) quantify and map the distribution and flux of me-

thane in the Baltic Sea, (2) analyse the controls on the relevant key biogeochemical processes, (3) integrate

seismo-acoustic mapping with geochemical profiling, (4) model the dynamics of Baltic Sea methane in the past

(Holocene period), present (transport-reaction models), and future (with predictive scenarios), and (5) identify

hot-spots of gas and potential future methane emission in the Baltic Sea.

The research project applied modern advanced technology and novel combinations of approaches to pursue the

listed goals i.a. multibeam bathymetry and seismo-acoustic profiling to map gas distribution and escape struc-

tures in combination with gravity coring. Further methane ebullition was identified and analysed by acoustic

flare imaging and sea surface emission by floating methane-gas flux chambers and “ferry box” monitoring. Al-

ready existing data were mined and combined with new observations to generate the first well-constrained

methane budget of a coastal sea, to map gas appearance in the seabed and to generate a predictive model to

understand and forecast methane fluxes as a function of environmental gradients, climate change, and contin-

ued eutrophication.

The BALTIC GAS research project was divided into 5 work packages (see also 3. Work package overview)

WP1: Project management, coordination and dissemination,

WP2: Data mining and GIS-mapping,

WP3: Gas and seismo-acoustic mapping,

WP4: Biogeochemistry,

WP5: Modelling and data integration,

The vast majority of the new and existing knowledge obtained during BALTIC GAS, however, was reached

through a tight (interdisciplinary) cooperation between work packages.

A short introduction that outlines the coordination of the BALTIC GAS research project is given below followed

by a presentation of the major outcome of the project. Additional information may be read on the BALTIC GAS

homepage (www.balticgas.au.dk, i.e. Deliverable 1.1) where all BALTIC GAS Deliverables are accessible (except

for two submitted manuscripts, i.e. Deliverable 4.4 and 5.3).

1.1 BALTIC GAS main results

• A novel approach was developed for the monitoring of gas in the seabed. Low frequency multibeam

backscatter data provided unique mapping capabilities of the distribution and depth of free gas. Com-

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bined with geochemical analyses of deep sediment cores this has yielded new high-resolution maps of

methane and gas distribution in selected areas of the Baltic Sea sediments.

• A novel approach was developed to quantify gas in the seabed by a Parasound sediment echosounder

using three individual wavelengths. By this use of multichannel seismo-acoustics combined with ad-

vanced data analysis it was possible to determine the gas volume in the sediment as well as the size of

gas bubbles and the vertical extent of gassy sediment. Such data are now used to verify model results on

methane accumulation and cycling.

• A novel application of a multibeam swath mapping system for sediment visualization was used to detect

and quantify gas bubbles rising from the seabed. A new cross-correlation technique similar to that used

in particle imaging velocimetry has now yielded impressive results with respect to unambiguous bubble

detection and remote bubble rise velocimetry.

• A detailed transect of seismic and geochemical data from non-gassy to gassy sediment in Aarhus Bay

combined with reactive-transport modeling has now provided strong evidence that free gas bubbles in

the Baltic Sea sediments migrate slowly upwards. When approaching the sulfate zone the gas re-

dissolves and the methane is effectively broken down sub-bottom.

• Hot-spots of methane outgassing from the sediment, often accompanied by pock-marks on the seafloor

found by multibeam bathymetry, have now been detected and mapped in several areas of the Baltic

Sea, in particular in the Polish and Russian sectors.

• Long-term monitoring of methane in the surface water throughout the central Baltic Sea by a “ferry-

box” mounted on a ferry between Travemünde, Gdynia and Helsinki has revealed the seasonal dynamics

and geographical distribution of methane. Combined with a transect through the entire water column

from the Bay of Bothnia to the Kattegat this has yielded a unique data set on methane in the Baltic Sea

and on the source strength of this green-house gas to the atmosphere.

• Based on data mining and on new data an extensive database on methane and related parameters has

been compiled and made publicly available through the BALTIC GAS homepage and the database, PAN-

GAEA. The data have also been used to develop new GIS-maps of the distribution of gas, the depth of

the methane zone, and the subsurface methane fluxes in the central basins of the Baltic Sea.

• Studies in the central basins were supplemented with detailed analyses of methane cycling in the Swe-

dish archipelago. Experiments indicated that 30-84% of the total methane flux in the sediment could be

attributed to bubbles. Yet, 98% of this methane was oxidized in the oxic water column, thus preventing

emission to the atmosphere. The remaining water-air flux was still 10-fold higher than in the central ba-

sins.

• Based on the large geophysical and geochemical data base compiled by BALTIC GAS, a transient reac-

tive-transport model was developed to understand the past and present methane cycle in the Baltic

seabed and the accumulation of gas. The model results now explain quantitatively how gas in the sea-

bed is controlled by the thickness of Holocene mud which is the main modern source of methane.

• Model predictions of future methane fluxes and the potential for accelerating gas emissions from the

seabed have shown a large robustness of the biogeochemical processes towards breaking down the me-

thane. This robustness could not have been predicted without the large amount of new data that could

verify the model and has been a key result of the project. The general model forecast is thus that the

predicted temperature increase of 1-2 oC and salinity drop in the Baltic Sea, together with an unchanged

level of eutrophication, is not expected to lead to a dramatic increase in the gas ebullition from the sed-

iments during this century.

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Fig 1. Baltic Sea geographical areas investi-gated during 15 BALTIC GAS cruises. Aarhus Bay (A), (B) Mecklenburg Bay, (C) Arkona Basin, (D) Bornholm Basin, (E) Gdansk Bay, (F) Baltic proper, (G) Gotland Deep, (H) Both-nian Sea, (I) Bothnian Bay), (J) Gulf of Fin-land, (K) Himmerfjärden. See also Table 2.

1.2 Project management, research cruises, and data collection

A total of 52 scientist, post docs, Ph.D-students, master students, and technicians were engaged in BALTIC GAS.

They participated during the project period (1/1/2009 – 31/12 2011) in BALTIC GAS workshops (Table 1; Deliver-

able 1.3), meetings between two or more BALTIC GAS institutions, Baltic Sea integrated seismo-acoustic training

courses (see 5. Educational activities), (see 6. Stakeholder events and other related activities), conferences and

stakeholder events (see 7. Meeting and conferences), and 15 cruises to the Baltic Sea (Deliverable 1.5) covering

in particular Aarhus Bay, Mecklenburg Bay, Arcona and Bornholm Basin, Gdansk Bay, Baltic proper, Gotland

Deep, Gulf of Bothnia, Gulf of Finland, and Himmerfjärden (a Swedish fjord about 50 km SSW of Stockholm; see

Table 2 and Fig. 1). See also BALTIC GAS scientific Reports (Deliverable 1.2).

Table 1. BALTIC GAS workshops organized during the project period: 1/1/ 2009 – 31/12 2011

Locality dates Hosting institution

Number of

participants

Bremen

Germany

February 4-6 2009 Max Planck Institute for Marine Microbiology 29

Warnemünde Ger-

many

September 16-17

2009

Baltic Sea Research Institute Warnemünde 24

Askö

Sweden

June 7-9

2010

Stockholm University

Department of Geological Sciences 24

Kaliningrad-region

Russia

February 23-24

2011

Shirshov Institute of Oceanology

Atlantic Branch, Russian Academy of Sciences 25

Aarhus

Denmark

November 1-3

2011

Center for Geomicrobiology

Department of Biological Sciences

Aarhus University

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The research cruises were the backbone of the BALTIC GAS re-

search project where targeted sediment sampling was done based

on seismo-acoustic measurement, the water column was sampled

and flux measurements across the water-atmosphere interface

were conducted (WP3 and WP4). Additionally mining of existing

seismic data was performed (WP2) mainly from BALTIC GAS institu-

tional ‘hard copy’ data i.a. The Baltic Sea Research Institute

Warnemünde, The Geological Survey of Denmark and Greenland,

Atlantic Branch of the P.P.Shirshov Institute of Oceanology Russian

Academy of Sciences, and Department of Geosciences at the Uni-

versity of Bremen. Also professor emeritus Dr. T. Flodén from The

University of Stockholm contributed with important interpretation

of seismic data from a large area offshore Gotland. The collected

seismic data were loaded to seismic workstations by the data own-

ers, the distribution of free gas was digitized, and the data com-

piled at GEUS as basis for GIS-mapping carried out by Alfred We-

gener Institute for Polar and Marine Research (see below and De-

liverable 2.1, 2.2, and 2.3) Table 3 and Fig. 2 gives an overview of

the seismic lines recorded or mined from archived data during BAL-

TIC GAS.

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Table 2. Cruises accomplished during BALTIC GAS (2009 – 2011). Investigations performed comprised i.a. seismo-acoustic measurements, sediment sampling and concomitant analyses to depict chemical and physical profiles, water column studies, and air-water flux measurements (see cruise reports for further details). Number of participating BALTIC GAS scientists and institutions are listed together with name of chief scientist.

Research vessel Region Date Investigations Chief scientist

persons /institutions

2009

RV Oceania Southern Baltic

Gulf of Gdansk

Vistula River mouth

Feb

20-27

seismo-acoustics Zygmunt Klusek

8 pers/2 inst

RV Aranda1)

Gulf of Finland

Northern Baltic proper

Apr

21-25

sediment Harry Kankaanpää

2 pers/2 inst

RV Limanda Himmerfjärden May

12 -17

sediment Volker Brüchert

6 pers/3 inst

RV Aranda1)

Gotland Basin

Bothnian Sea and Bay

Jun

4-17

sediment Alf Norkko

2 pers/2 inst

RV Ladoga Gulf of Finland

(i.e. Vyborg Bay)

Jun 30 -

July 2

seismo-acoustics

sediment

water column

Nikolay Pimenov

6 pers/1 inst

RV Merian1)

Gotland Basin


Aug 28 -

Sep 9

sediment

water column

Falk Pollehne

1 pers/1 inst

RV Susanne A Aarhus Bay Oct 6 sediment Henrik Fossing

5 pers/3 inst

RV Oceania Southern Baltic

Slupsk Furrow

Gdansk Deep

Hel Peninsula region

Nov

5-16

seismo-acoustics

sediment

Zygmunt Klusek

14 pers/4 inst

RV Poseidon MecklenburgBay Arco-

na Basin Bornholm

Deep

Stolpe Foredelta Got-

land Deep

Nov 27 -

Dec 17

seismo-acoustics

sediment

water column

Rudolf Endler

11 pers/4 inst

2010

RV Susanne A Aarhus Bay May

5-7

sediment

Henrik Fossing

5 pers/3 inst

RV Limanda Himmerfjärden Jun

10 -14

sediment

water column

Volker Brüchert

5 pers /2 inst

RV Prof Shtokman Russian Sector of

Gdansk Basin

(i.e. NW pers)

Jun

20-27

seismo-acoustics

sediment

water column

Vadim Sivkov

2 pers/2 inst

RV Merian Mecklenburg Bay

Arkona Basin

Bornholm Basin

Gotland Deep


Jul 31 -

Aug 21

seismo-acoustics

sediment

water column

Gregor Rehder

29 pers /7 inst

2011

RV Limanda Himmerfjärden

Jun

10-16

water column

air-water flux

Volker Brüchert

5 pers/2 inst

RV Limanda Himmerfjärden Oct

20-21

water column

air-water flux

Volker Brüchert

2 pers/1 inst 1)

BALATIC GAS scientist(s) invited to participate on cruise organized by other BONUS-project partner

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Sediment parameters were measured during 12 out of the 15 cruises and comprised a vast amount of both bio-

geochemical and physical observations in combination with sediment characterization and occasionally rate

measurements of methanogensis, anoxic oxidation of methane, and sulphate reduction (see cruise reports for

details: http://balticgas.au.dk/balticgasaudk/project/workingareasandcruises/ Deliverable 1.5). The number of

parameters recorded differed between sediment cores but as a key parameter to BALTIC GAS methane (CH4)

was measured in all sediment cores and sulfate (SO4

2-) in most. Thus sediment data submitted to the common

database PANGAEA (http://pangaea.de/) comprised (when measured) (Deliveable 1.4):

A) Pore water chemistry: CH4, δ13

CH4, SO4

2-, H2S, Cl

-, Fe

2+, Mn

2+, NH4

+, PO4

3-, alkalinity, dissolved inorganic

carbon (DIC), δ13

DIC, acetate and other volatile fatty acids (VFA),

B) Solid phase chemistry: acid volatile sulfide (AVS), chromium reducible sulfur (CRS), ‘metals’, nutrients,

Fe(solid phase), Pb-210, total nitrogen (TN), total carbon ( TC), C/N-ratio, total organic carbon (TOC),

δ13

TOC,

C) Process rates: methanogensis, anoxic oxidation of methane, and sulphate reduction

D) Physical parameters: temperature, density, porosity

Sampling of the water column comprised CH4, δ13

CH4, and H2S and was always accompanied (i.e. initiated) by a

conventional CTD cast. The water column data were likewise submitted to PANGAEA.

Fluxes of methane from the sediment to the bottom water and across the sea surface in coastal and open-sea

Baltic waters were determined by modelling from concentration data and by direct flux measurement. Sea-air

exchange was quantified by data from an autonomous measurement system mounted on the ferry M/S FINN-

MAID in November 2009 commuting regularly between Travemünde (Germany), Gdynia (Poland) and Helsinki

(Finland) to measure methane and carbon dioxide concentration in the surface waters. Direct sea-air fluxes of

Fig. 2. Seismo-acoustic lines (i.e. data) complied in a common database by GEUS. Black lines are ar-chive data. Red lines show seismo-acoustic data measured during Baltic Gas.

Table 3. Seismo-acoustic data (measured and archived) complied in a common database by GEUS. See Fig. 2.

Data source

Acoustic

line

length

(km)

Archive data University of Stockholm 2,700

Archive data Shirshov Institute of

Oceanology

Atlantic Branch, Russian

Academy of Sciences

18,300

Archive data Baltic Sea Research Insti-

tute Warnemünde 5,100

Archive data The Geological Survey of

Denmark and Greenland

(GEUS)

1,900

Archive data Department of Geoscienc-

es , University of Bremen 900

Acoustic data measured during Baltic Gas 4,600

Total seismic database 33,500

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methane were determined with floating chambers in near-shore areas of the Southern Stockholm archipelago,

in particular theHimmerfjärden estuary.

The BALTIC GAS coordinators organized that the modellers received seismo-acoustic data and results from in situ

sediment measurements on a regular basis and that data were exchanged between BALTIC GAS scientists, par-

ticularly at BALTIC GAS workshops. Here also new ideas, hypotheses, and theories were discussed based on the

most recent findings and the modellers’ knowledge base’ was improved leading to the development of robust

algorithms and models. These models proved highly valuable in bringing the many point observations into a

larger context and in confirming hypotheses concerning, e.g. the transport-reactions models.

1.3 Methane gas and seismo-acoustic mapping

During the BALTIC GAS research project seismo-acoustic surveying was the initial and most efficient method to

find and map free methane gas in the sediment and water column. In particular when combined with direct

methane measurements in sediment cores and water column samples.

In BALTIC GAS, acoustic monitoring of sediments was performed by use of a broad spectrum of acoustic tech-

niques and equipment i.a. singlebeam echo-sounders with frequencies of 12, 38 and 200 kHz, low frequency

multibeam echo-sounder (50 kHz ELAC), parasound sediment echo-sounder (4.2, 18,5 and 42.8 kHz) , Innomar

sediment echo-sounder (5, 10 and 15 kHz), high resolution broadband chirp echo-sounder (1 – 10kHz), single-

channel Boomer (2 – 4kHz), single-channel Sparker (1kHz), and multichannel Airgun seismics (200 Hz).

The echo-sounder transmits high frequency sound waves down to the sea floor and further into the seabed.

Depending on the frequency, more or less of the energy is reflected at the sea floor, which enables a precise

Fig. 3. A seismo-acoustic transect crossing methane gas saturated sediment in Bornholm Basin across a distance of about 8 km (about 90 m water depth) between site 374200 (55o14.973N/ 15o26.147E) and site 374180 (55o20.329N/ 15o26.237E). Methane gas bubbles efficiently absorb the acoustic energy and thus ‘blanks’ information from the under-lying sedimentary strata. Yellow vertical lines show position and length of gravity cores sampled (see also Fig. 11).

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determination of the water depth with an accuracy of a few centimeters. Lower frequency sound waves pene-

trate deeper into the sediment depending on the hardness of the seabed due to differences in mineralogy and

other geological features. The sound waves penetrate relatively easy into fine grained sediments as mud, silt,

and clay, whereas penetration depths are very limited in sand, gravel and glacial till. Thus, the seismo-acoustic

data obtained give an acoustic cross section of the seabed where the sediments and sediment strata are seen by

‘acoustic imagery’ as a vertical reflector pattern profile (Fig 3). Methane gas bubbles, however, efficiently absorb

the acoustic energy and thus ‘blank’ information from the underlying sedimentary strata. Hence by ‘acoustic

imagery’, free methane gas is observed as a conspicuous, more or less homogeneous blanking on the seismic

‘picture’ or ‘scan’ (Fig 3).

During most BALTIC GAS cruises and at most stations studied hydroacoustic singlebeam echo-sounders were

used as the standard tool for remote sensing of free methane gas in the seabed and water column. However,

during BALTIC GAS also new seismo-acoustic techniques were introduced and demonstrated as superior solu-

tions for shallow gas mapping compared to singlebeam techniques as explained below.

1.3.1 Spatial mapping of shallow gas using a low frequency multibeam echosounder

Bornholm Basin in the Baltic Sea (80m) hosting free methane gas was surveyed with low and high frequency

multibeam acoustic equipment accompanied by standard sub-bottom profiling.

The gathered multibeam backscatter data (Fig. 4a) revealed distinct differences between areas with and without

gas. Compared to standard technique singlebeam data (Fig. 4b) and geochemical analysis (Fig. 4a, cs1 and cs2)

BALTIC GAS scientist for the first time demonstrated a perfect match in regard to sensing free methane gas with

Fig. 4. (a) Backscatter amplitude chart of EM120 with a transition zone between bluish/no gas and yellowish/shallow gas areas; the inlet shows amplitude data gathered from the 95 kHz system not showing any transition, (b) PARA-SOUND sub-bottom data recorded along the blue and red line in (a) starting at 08:15 UTC. The transition zone between shallow gas (right) and no shallow gas (left) plots exactly at the same time as seen in the multibeam data (a). On figure (a) and (b) the blue and red line indicate the two sediment types ‘mud’ and ‘mud hosted with shallow gas’, respectively.

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this method (Deliverable 3.3). In contrast no data patterns were observed in the high frequency multibeam sur-

vey (Fig. 4a insert). This emphasized the superior potential of our low frequency approach where the low fre-

quency pulses not only penetrated the seafloor up to 10 m but the ‘acoustic gas front’ also mimicked the gas

front observed form direct measurement in gravity cores. Even small gas pockets clearly emerged as “bright

spots” in the backscatter data on the very outer swath at 140° (Fig. 4a, patch in northeasterly region) making the

multibeam system a reliable tool for 2D wide-angle/spatial mapping of shallow gas.

The technique just introduced was further tested in

the Botnian Sea (Fig. 5). The respective survey

shows more complex morphology with outcropping

till on the seafloor and subbottom channels within

the Holocene mud locally hosting pockets of shal-

low gas. The multibeam was run in parallel with the

subbottom profiler. Till, mud, and gas-bearing mud

clearly plotted as different features in both da-

tasets. The till appeared as real bathymetric high

(Fig. 5), the mud caused deeper bathymetric meas-

urements due to penetration; whereas the shallow

gas within the mud caused a sudden bathymetric

increase in the transition zone.

Even though earlier studies demonstrated the feasibility of backscattering strength analysis in regard to sensing

shallow gas, no multibeam studies exist revealing subbottom gas submerged several meters below the seafloor

in two dimensions. Given the high sensitivity and the large coverage shown in our study we attribute low fre-

quency multibeam sounders a great potential in soft sediments in regard to spatial mapping of shallow gas, iden-

tifications of individual gas pockets, and to locate buried objects.

1.3.2 Towards quantification of shallow free gas in Baltic Sea sediments

The presence of free gas bubbles introduces fundamental changes in the properties of sediments and their re-

sponse to seismic sound waves. While high frequency acoustic waves are strongly attenuated, lower frequency

seismic waves are able to penetrate gas-charged sediment layers. However, the speed in gas-bearing sediment is

significantly reduced due to lower wet bulk density and modification of other elastic and sediment physical

properties. Thus by careful determination of interval velocity from raw multichannel seismic data, we were able

to estimate the amounts of free gas in the sediment.

Recording the reflected seismic waves with an array of hydrophones/channels allowed an indirect measurement

of their velocity from the curvature of reflection hyperbolae (conventional interactive velocity analysis). In addi-

tion, we performed velocity analysis on pre-stack time migrated data, which, although time consuming and

computationally intensive, allowed the determination of the velocity field over gassy areas more accurately and

more extensively in space than hitherto done. Depending on stratification (identifiable reflectors), the accuracy

and resolution varied significantly. In general, velocities dropped from about 1450 m/s in non-gassy fine-grained

surficial sediments down to a few hundred m/s in the gas-charged zone. Beneath the gas patches, in the post-

glacial and glacial sediments, velocities again increased (>1500 m/s).

Fig. 5. Pseudo bathymetric presentation after application of a slope filter (Botnian Sea) Red areas show outcropping till seafloor, wheras blue and green data represent soundings reflected from subbottom features like gas and submerged till.

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To quantify the gas content based on the velocity field, we used Anderson & Hampton’s geoacoustic model

(1980), which described the relationship between compressional wave velocity and the physical properties of

gas-bearing marine sediments. In the model, gas bubbles were assumed to be fully contained within the pore

space, thus modifying its compressibility. Taking the interval velocity values between reflectors, free gas content

in the pore volume could be estimated (Fig. 6). Values of the free gas content at the test location in the Born-

holm Basin ranged from 0.1 to 2%, where sensitivity becomes reduced. These numbers were basically in agree-

ment with the modelling results.

When excited, gas bubbles in the sediment resonated at a fundamental frequency, which was mainly deter-

mined by the bubble size and physical properties of the surrounding medium. As a result, acoustic behaviour

Fig. 6. High resolution multichannel seismics performed with a GI gun with a central low frequency of 200 Hz and a 50 m long streamer with 48 channels (seismo-acoustic transect GeoB10_044). (a) The interval velocity values between reflectors (m/s) showing significantly reduced velocities in the gas charged sediment (dark blue pixels in the white framed sediment section) compared to gas free sediments outside the frame. Depth below surface is expressed in m/s as the two-way travel time (TMT) i.e. travel time from source and back to receiver. The offset shows the distance (m) from the start of transect in the south to the endpoint in the north. The vertical solid line shows the depth of the sea-floor. (b) The interval velocity values between reflectors in the gas charged sediment (i.e. white frame in panel (a)). (c) Free gas content estimated from ‘interval velocities’ up to 2% gas of the sediment pore volume (i.e. gas replacing pore water).

12

was different below, at and above the resonance frequency but attenuation due to the scattering effects would

be strongest close to the resonance frequency.

By imaging shallow gassy sediments at a broader frequency range, gas bubbles could be physically characterized

from their acoustic response. In the Bornholm Basin, gassy areas were surveyed with three frequencies of the

Parasound sediment echo-sounder (4.2, 18.5 and 42.8 kHz). High reflection amplitudes from and strong signal

attenuation beneath the gas front occurred at the lowest imaging frequency of the Parasound, although natural

attenuation increased with frequency. Accordingly, this effect could be attributed to bubble resonance behav-

iour, which was not observed at the two higher frequencies (Fig. 7). Based on the theoretical considerations of

Anderson and Hampton (1980) and for typical sediment properties, bubble size distribution was likely to peak

near a diameter of approx. 2 mm (4.2 kHz) with the smallest bubbles larger than 0.2-0.4 mm (42.8 and 18.5 kHz,

respectively).

These new results obtained by the BALTIC GAS project represent major scientific progress in the quantification

of gas distribution and gas volume in marine sediments based on geophysical analyses. Using a diverse suite of

seismic and acoustic equipment in parallel together with advanced methods of data processing and analysis,

remote profiling measurements come within reach for routine gas quantification. While larger uncertainties still

exist and basic physical concepts still have to be developed and tested, the acquired results for gas content and

bubble sizes seem to be in good agreements with evidence from biogeochemical measurements and modelling.

Fig. 7. Seismo-acoustic signal received from a Parasound sediment echo-sounder operated at frequencies of 4.2, 18.5, 42.8 kHz along an appox. 700 m transect in Bornholm Basin from NW (left) to SE (right). Amplitudes at 4.2 kHz, close to the resonance frequency of about 2 mm bubble size, show scatter in the gas-charged layer and decrease beneath. The can be considered as horizontal variation in this decrease can be considered as a measure of the gas content. At the 18.5 and 42.8 kHz, above resonance frequency, the effect of gas is only revealed in generally lower amplitudes than values observed in adjacent gas-free sediments. Depth below surface is expressed in m/s as the two-way travel time (TMT) i.e. travel time from source and back to receiver. The offset shows the distance (m) from the start of transect in the NW to the endpoint in the SE.

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1.3.3 Rising of methane gas bubbles through the water column and pockmark distribution in the Gdansk Basin

State of the art multibeam seismo-acoustic techniques were used to remotely investigate gas bubbles rising

through the water column. BALTIC GAS scientists successfully deployed a prototype multibeam ecco-sounder

that allowed us to image the rising of methane gas bubbles through the water column and to sense the respec-

tive rise pattern of individual gas bubbles released from the sediment i.a. from pock marks in the seafloor (Fig. 8,

Deliverable 3.3).

Investigations were carried out in the Gdansk Basin by the Institute of Oceanology, Polish Academy of Science

and the Atlantic Branch of the P.P.Shirshov Institute of Oceanology, Russian Academy of Sciences. Acoustical

surveys with multi-beam and side scan sonars were focused on mapping of pockmarks and detection of gas bub-

bles released from the seafloor. The presence of shallow gas in the Gdansk Basin area was manifested by differ-

ent indications such as gas-saturated mud (including gas pockets), pockmarks, and gas outflow within pockmark

(Fig. 9). The total area covered by pockmarks in the Gdansk Basin was about 27 km2

(25.1 km2

in the Polish sector

and 1.7 km2

in Russian sector, Table 4).

One area with pockmarks was located in the north-eastern part of the Gdansk Deep slope. Seven pockmarks of

various morphologies, typically elongated from the southwest to the northeast, were revealed in this area. The

horizontal length of the structures varied from 200 to 900 m, with a mean width of about 150-200 m and depths

of 1-3 m below the surrounding seafloor. Apart from individual pockmarks, groups of 2-3 of these depressions

were also observed. Usually, pockmarks were surrounded by gassy mud or located at its periphery. This distinct

pockmark area was situated on a cross-section of different fracture zones with weakened zones of the sedimen-

tary cover (supply channels, such as faults and furrows), which serve as a pathways for deep gas.

Fig. 8. (a) Successive echo-image frames recorded during water column imaging with SB3050 showing Rosette (RWS) downcast, contact with gassy sediments, and induced bubble escape into the water column. (b) “Beam-Slice” presentation with the x-axis representing the ping times in seconds where the y-axis is two-way-travel time [s]. Hori-zontal features represent non-buoyant microbubbles (I) where to the right some ascending bubbles occur (II).

14

A relatively large single pockmark of 3 km length and 0.4 km wide elongated in south-north direction was dis-

covered and mapped in the Polish sector of the Gdansk Deep (54.738N/19.186E, center position). Additionally

pockmarks were identified between 55.197N – 55.072N and 18.907E – 19.018E by use of broad banded echo-

sounding. Acoustically recognized pockmarks cross sections ranged from 20 to 200 m in diameter.

Fig. 9. Distribution of gas outflow (at arrow), pockmarks and shallow gas in the Polish and Russian EEZ of Gdansk Bay. The gas outflow is also shown on Fig. 10.

Table 4. Pockmarks in Gdansk Basin Polish and Russian EEZ.

Polish EEZ Russian EEZ (offshore Kaliningrad)

Positions Area, km2 Positions Area, km

2

55.18N/18.94E Pockmark 1,5 55.36N/19.81E Pockmark 0.06




54.57N/19.16E Gas outflows 0,5 55.35N/19.78E Pockmark 0.49

55.32N/19.76E Pockmark 0.30

55.32N/19.74E Pockmark 0.07

total 25.1 total 1,71

15

An active gas outflow within pockmark (Fig.10)

was documented in the southern part of the Gulf

of Gdansk, with the center positioned at the

54.571N/19.165E (Table 4). The size of the struc-

ture was determined using a 12 kHz echo-

sounder to be about 250 – 300 m. Gas bubbles

emanating from the sea floor at 80 m water

depth were observed to ascent at least up to a

water depth of 30 m. An interesting feature of

this pockmark was that the older and bigger low

gas flux pockmark area confined the more active

and deeper structure. Using calibrated echo-

sounders the radius of the raising gas bubbles

was estimated to range from about 2 mm up to

10 mm.

The largest identified acoustical anomaly, presenting gas-saturated muds, was located in the central part of the

Gdansk Deep at depths of 104-106 m. As known from literature the sub-horizontal pre-Quaternary surface here

is complicated by valley furrows, associated with a system of latitudinal extended faults. The basement of the

geoacoustical anomalies reached the underlying Mesozoic layers and was usually associated with faults. Weak

fluid fluxes and/or abundant supply of sedimentary material from nearby underwater slopes and the coast may

have caused partial or full burial of the local seabed depressions and thus explained the absence of pockmarks in

this area.

In the Polish sector gas pockets, included in ‘shallow gas’ areas(Fig. 9), were mostly localized in the area of the

Gdansk Basin, especially in the vicinity of the Hel Peninsula. Occurrence of such structures was associated with

muddy sediments and high sedimentation rates of organic-rich matter at rates from 1.5 to over 2 mm per year.

Most of the gas generated in this area was mostly produced by bacteria in the Holocene sediments. The total

area in the Polish sector covered by gas-bearing sediments was about 440 km2.

1.4 Sediment and water column biogeochemistry and physical characters

For an extensive quantification of methane concentrations in Baltic Sea sediments and in order to depict other

chemical and physical profiles direct measurements were performed in the sediment (Deliverable 4.1). Based on

the seimo-acoustic surveys targeted sediment sampling was done along transects reaching from sediments with

deep or no ‘methane-reflection’ of the seismic signal (i.e. non-gaseous sediment) to sediments with methane

saturation and thus a sharp reflection (i.e. gaseous sediment Fig. 3 and Fig 11). Depending on stations and cruis-

es a variety of sampling equipment was applied, i.a. gravity corer, Rumohr Lot corer, Frahm Lot corer, and multi-

ple corer. An important part of the characterization of gas-bearing sediments was done both by a general core

description (Deliverable 4.3) and by physical property studies (Deliverable 3.1) on cores obtained during an ex-

tensive coring program of the Baltic Gas expeditions. Multisensor core logging was used to estimate basic physi-

cal properties of gas free and gas charged sediments. The results (Fig.12) were used for interpretation of sedi-

Fig. 10. The acoustic transect through the gas outflow within the pockmark showing gas bubbles emanating from the sea floor (at 80 water depth) ascending up to a water depth of about 30 m. The image was obtained with a 12 kHz echosounder. See location at Fig. 9.

16

ment echo-sounder records. From these data the thickness of the Holocene mud (deposits of the Littorina Sea

from the past ca. 9000 years) and of the older deposits from earlier Baltic Sea Stages can be estimated.

Other ‘highlights’ from the sediment and water column studies as well as methane flux measurements across

the sediment-water-atmosphere interfaces are presented below and on the BALTIC GAS home page.

1.4.1 Methane in Baltic Sea sediments

Methane (CH4) was produced in great quantities in Baltic Sea sediments by methane-producing microorganism

when organic matter was degraded through a process named methanogenesis. However, sulfate-reduction

dominated the upper sub-surface layers because sulfate reducing bacteria are energetically more effective in the

degradation of organic matter than methane-producing microorganisms. Therefore methanogenesis only took

over deeper in the sediment, below the sulfate-methane transition (SMT) zone, where sulfate was exhausted or

occurred at very low concentration (Fig. 13).

In the Baltic Sea methane was continuously formed in the seabed and gas bubbles developed at sediment

depths where the methane concentration exceeded saturation at ambient hydrostatic pressure. However, by far

most of the methane was effectively scavenged before it reached the sediment surface. In the sub-surface sedi-

ment, where there was no oxygen, sulfate was the oxidant for methane which was converted to carbon dioxide.

Most methane was oxidized at the depth to which sulfate penetrated also known as the sulfate-methane transi-

tion (SMT)-zone (Fig. 13). This microbially mediated anaerobic methane oxidation accounted for >90% of the

entire methane flux in the sea floor and, therefore, played a critical role as a barrier against methane emission to

the water column and further into the atmosphere.

Fig. 11. Methane concentrations profiles determined in sediment cores sampled along a transect in Bornholm Basin crossing the methane gas saturated sediment shown on Fig. 3. (a) Site 374200 (depth 93 m), (b) Site 374190 (depth 91 m), (c) Site 345175 (depth 93 m), and (d) Site 374170 (depth 93 m). Solid line and stipulated line show in situ CH4 satu-ration and CH4 saturation at 1 atm, respectively. Methane is rapidly lost from the sediment core when brought on deck due to a pressure decrease. Thus the scattered appearance of the CH4 concentration profile at Site 374190 (b) – i.e. sediment from the gas saturated sediment – is due to a significant loss of CH4 before the sediment was subsampled. At the Sites 374200 (a) and 345175 (c) the in situ CH4 concentration was below saturation and not detected at all at Site 374170 (d).

17

Fig. 12. Results of multisensor logging of gravity core 374200-06GC in Bornholm Basin (see also Fig. 3 and Fig. 11). The deposits of the different Baltic Sea stages are separated by yellow lines and named in red letters. The measured parameters are:" vp" - pwave velocity, "dwb" -wet bulk density, "vsh" - vane shear strength torsional moment , "con-ductivity" - electrical conductivity, "Water cont" - gravimetric bulk water content, "suszeptibility" - magnetic volume suszeptibility, "Ignition loss" - loss of ignition, "colorvalue H S V" - from core photo extracted color values of the HSV model. A short sediment echosounder record (SES) is attached at the right side for comparison.

Fig. 13. Concentrations of dissolved methane (CH4) and sulfate (SO4

2-) in pore waters from Station 011 (Mecklenburg Bay) obtained during RV Merian cruise Jul 31 - Aug 21, 2010. In situ CH4 concentration at 40 m water depth (10 ‰ salinity, 9.3oC) and CH4 saturation at 1 atm (on deck) are shown on left figure. Expanded figure (right) show the SO4

2- and CH4 flux gradients, blue and red solid lines, respectively. At this station the upward CH4 flux (red arrow) of 430 µmol m-2 d-1 is balanced by the downward SO4

2- flux (blue arrow) of 460 µmol m-2 d-1 when CH4 is oxidized (con-sumed) in the sulfate-methane transition zone (yellow box) by reduction of SO4

2-.

18

Fig. 14. GIS-map of the spatial distribution of the sulfate-methane transition zone’s (SMTZ) depth (m) in Baltic Sea sediments. Observations of concomitant presence of both sulfate and methane were predominantly done in muddy sediments with a SMTZ median value of about 0.35 m caused by a high content of particulate organic matter and thus increased production of methane. Signatures of SMTZ-depth show the performed observations.

19

In the close vicinity to the SMT-zone, concentration gradients of sulfate and methane were steep and well de-

fined and the sulfate flux down to this interface balanced the methane flux from the deep sub-surface (Fig. 13).

From the perspective of biogeochemical analysis and sampling techniques, the depth of the SMT-zone was de-

fined by pore water studies, whereas determinations of methane fluxes from sediments into the water column

or atmosphere were much more demanding. Therefore, the depth of the SMT-zone provided a robust proxy – in

terms analytical accuracy and data availability –for identification of regions at the Baltic Sea seafloor where high

or low methane production as well as methane

fluxes into the water column were to be expected.

Figure 14 shows GIS-maps of the spatial distribu-

tion of the SMT depth with respect to sediment

types; bedrock, hard bottom, hard clay, mud, and

sand (Deliverable 2.2 and 2.3). As expected the

analyses revealed that shallow SMT-zone depths

were predominantly observed within muddy sedi-

ments with median values of about 0.35 m due to

the high content of particulate organic matter and

thus increased sulfate reduction and production of

methane. Additionally Fig. 15 shows a compilation

of pore water methane fluxes to the sediment sur-

face based on the various sediment surveys con-

ducted during Baltic Gas (Deliverable 4.2). The

highest benthic flux rates were measured in the

inshore areas of Himmerfjärden followed by the

central Gotland Basin and the Arkona Basin. Low

rates, with the exception of a seep site in the Both-

nian Bay, were measured in the northern Baltic.

In conclusion BALTIC GAS scientists observed (with very few exceptions) that free methane in the Baltic Sea in

general was restricted to Holocene marine mud areas and that a minimum threshold thickness of mud was re-

quired before free methane gas was observed in the seabed (see 1.5 Modelling methane dynamics in the Baltic

Sea below). Further, detailed sediment studies in combination with seismo-acoustic investigations at a variety of

locations in the Baltic Sea showed that the Holocene mud deposits in general were thinner than the threshold

thickness for bubble formation and that the existing areas with free methane could be characterized as geologi-

cal sediment traps.

1.4.2 Holocene mud deposits and presence of free methane gas (an example from Aarhus Bay)

Based on extensive acoustic survey and sediment sampling programs performed during previous projects, i.a.

METROL (EU 5th

Framework), Aarhus Bay sediments were proven ideal to BALTIC GAS scientist for a detailed

study on the control mechanisms of methane accumulation in Baltic Sea sediment and their relation to Holocene

mud thickness. Seismic studies had previously shown accumulation of free CH4 gas in the central area of the bay

Fig. 15. Compilation of the diffusive methane flux rates towards the sediment surface determined during BALTIC GAS. Fluxes were calculated form the methane concentra-tions gradients in the pore water samples (see Fig. 13).

20

where more than 4-5 m thick homogenous mud had accumulated. The lithology suggests that most CH4 is

formed in the Holocene mud with little contribution from deeper layers of organic-poor glacial clay1.

Thirteen 3-7 m long sediment cores were collected in October 2009 and May 2010 by gravity coring at very close

distances of 20-200 m along a 600 m transect crossing from gas-free into gas rich sediment (Fig. 16). The Holo-

cene mud thickness increased gradually

along the transect and the measured pore

water gradients CH4 and SO4

2- increased in

steepness (Fig. 17 Deliverable 4.4). The

SMT-zone shifted up closer to the sediment

surface when moving from the gas-free into

the gas-rich area with a SO4

2-/CH4 flux ratio

close to 1 and thus in accordance to the

theoretical value. We extrapolated the

depth trend of organic carbon mineraliza-

tion rates deep down into the methane

zone to estimate the total depth-integrated

rates of methanogenesis. From these results

we conclude that the thickness of the organ-

ic-rich Holocene mud layer, and thus the

sedimentation rate, was the main parameter controlling the initiation of sub-surface methane accumulation and

free gas formation (Fig. 18). The relationship between these factors is, however, non-linear due to a positive

feedback whereby a small upward displacement of the SMT exposes sediment with more reactive organic mat-

ter to methanogenesis and thereby enhances the overall methane production. A higher sedimentation rate has a

similar effect by increasing the burial of reactive organic matter down below the SMT where it strongly stimu-

lates methanogenesis. Due to the positive feedback, the SMT is further shifted upwards and the methane fluxes

are increased by the transition from non-gassy to gassy sediment. This mechanism of free gas formation in Baltic

Sea sediments were further confirmed through sediment modeling as explained below (see 1.5.2 Environmental

controls of gaseous methane production in the Baltic Sea (an example from Aarhus Bay below).

1.4.3 Distribution and temporal variability of dissolved methane in the water column of the Baltic Sea

The distribution of dissolved methane in the water column of the Baltic Sea was extensively investigated based

on analysis of data gathered prior to or during the BALTIC GAS project by partner IOW. A strong correlation be-

tween the vertical density stratification, the distribution of oxygen, hydrogen sulfide, and methane was identi-

fied (Fig. 19). A widespread release of methane from the seafloor was indicated by methane concentrations

increasing with water depth. The deep basins in the central Baltic Sea showed the strongest methane enrich-

ments in stagnant anoxic water bodies, with a pronounced decrease towards the pelagic redox-cline and only

slightly elevated surface water concentrations. In general, the low-salinity basins in the northern part of the

Baltic Sea were characterized by lower water column methane concentrations and with surface water saturation

values close to the atmospheric equilibrium (Fig. 19).

1 for further details see: see Jensen, J.B., and o. Bennike (2009) Geological setting as background for methane distribution in Holo-

cene mud deposits, Arhus Bay, Denmark. Continental Shelf Research, 29(5-6), 775-784

Fig. 16. Seismic profile of Aarhus Bay sediment showing the Hol-ocene mud layer (56º N 6.81’, 10º E 24.71’ to 56º N 6.64’, 10º E 25.21’). The top of the free gas layer (= free gas depth, FGD) is shown by the upper dashed line. Below the FGD the presence of free gas in the Holocene mud results in acoustic blanking and concealment of underlying sediments. The base of the mud layer in the gassy sediments is extrapolated from the slope in the non–gassy sediments (lower dashed line). The sampling stations and penetration depth of the gravity cores are indicated.

21

Fig. 17. CH4 and SO4

2- profiles along the transect shown on Fig. 16. Stations M21 – M26 are in the gas-free area with M26 at the transition and M27 – M30 are in the gassy sediment area. The gray line represents the position of the SMT (defined at equi-molar concentrations of CH4 and SO4

2-, i.e. [CH4] = [SO42-].

Fig. 18. Factors leading to increased CH4 production along the transect relative to station M24 (the first station with quantifiable CH4 production (see Fig. 16 and Fig. 17) based on integration of mineralization rates determined from sulfate reduction rates. The upward shift of the sul-fate-methane transition is contributing much more to the total methane production than is the thickening of the Holocene mud layer.

22

Fig. 19. Oxygen (b) and methane (c) concentration along two transects across the Baltic Sea sampled in summer 2008. Hydrogen sulfide was converted into negative oxygen equivalents. The insertion in a1 displays the location of the two transects (note red and green color code), insertion a2 shows the bathymetry of the Baltic Sea and the location of the main basins (K, Kattegat; BS, Belt Sea; AB, Arkona Basin; BB, Bornholm Basin; WGB, Western Gotland Basin; EGB, Eastern Gotland Basin; A, Åland Sea; BOS, Bothnian Sea; BOB, Bothnian Bay; GF, Gulf of Finland). The extension of the individual basins is also indicated at the top of the oxygen section. The data obtained from the red (station 3075 to 3041) and green transect (station 3005to 3095) are displayed on the left and right side in Figure 1bc, with the stations labeled at the top of Figure 1b for better orientation. Modified from Schmale et al. (20102).

Based on the comprehensive analysis represented in this basin-wide data set, more detailed investigations of the

water column were performed. The strong link between enhanced methane concentrations and oxygen defi-

ciency was demonstrated by vertical profiles from fixed locations at stations with frequent oxic/anoxic shifts of

the bottom water sampled various times (Fig. 20). The mechanism of this fast buildup of a dissolved methane

pool in the water column is still under investigation, and demonstrates the sensitivity of the methane cycle to

changes in ventilation and to the extent of hypoxic and anoxic areas in the Baltic Sea.

1.4.4 Continuous measurement of surface methane concentrations – ships of opportunity

Within the framework of Baltic Gas, the partner IOW developed and operated a system which allows the contin-

uous measurement of methane and carbon dioxide concentrations in surface waters autonomously using ships

of opportunity (Fig. 21; Deliverable 4.2). The analytical setup consists of a methane and carbon dioxide analyzer

based on off-axis integrated cavity output spectroscopy (ICOS) coupled to an established equilibrator setup.

2 Schmale, O, J. Schneider v. Deimling., W. Gülzow, G. Nausch, J. Waniek, G. Rehder (2010) The distribution of methane in the water

column of the Baltic Sea. Geophysical Research Letters, 37, L12604,

23

Fig. 20. Methane concentrations (dots) and hydrographic parameters at a station in the central Bornholm Basin in De-cember 2009 (left), and August 2010 (right, with high resolution sampling of the lower 5m). Note jump in methane scale. Bottom waters were characterized by inflow of oxygenated waters at the bottom in December and anoxic conditions in summer, in conjunction with an increase of dissolved methane concentrations from 20 to 80 nM over this period of time.

Fig. 21. Schematic of a system for the contin-uous measurement of CH4 and pCO2 in sur-face waters using off-axis ICOS. The system is installed on the ferry Finnmaid run by Finn-lines.

24

The analyzer used a highly specific infrared band laser with a set of strongly reflective mirrors to obtain an effec-

tive laser path length of several kilometers. This allowed us to detect methane and carbon dioxide with high

precision (better 0.1%) and frequency. The system was installed in November 2009 on the cargo ship Finnmaid

(Finnlines) that commutes regularly in the Baltic Sea between Travemünde (Germany), Gdynia (Poland) and Hel-

sinki (Finnland).

Figure 22 shows the first complete year of opera-

tion (2010), with more than 300 days of operation,

allowing hitherto unrivaled insights into the spatio-

temporal development of sea-air disequilibria and

fluxes for methane in a marginal sea, and the analy-

sis and identification of the controlling parameters.

Surface methane saturations with general minimum

values from December to February and maximum

values during August till September showed great

seasonal differences in shallow regions like the

Mecklenburger Bight (103-507%) compared to

deeper regions like the Gotland Basin (96-161%).

Parameters influencing methane supersaturation

and emission to the atmosphere, like temperature,

wind and mixed layer depth, as well as processes,

like upwelling, mixing of the water column, and

sedimentary methane emissions, were investigated.

Highest methane fluxes were observed during the autumn and winter period. The annual interaction of stratifi-

cation and mixed layer depth was found to be a key parameter for methane fluxes in deeper regions like Gulf of

Finland or Bornholm Basis. Methane fluxes from shallow regions like the Mecklenburger Bight are controlled by

sedimentary production and consumption of methane, wind events and the temperature induced change of the

solubility of methane in the surface water.

1.4.5 The role of the inshore and littoral region for methane emissions from the Baltic Sea

Investigations of the inshore coastal fluxes from the sediment and to the atmosphere focused primarily on the

southern Stockholm archipelago with the eutrophied Himmerfjärden (Deliverable 4.2). In addition to water col-

umn methane concentration measurements, air measurements and floating methane-gas flux chambers (for the

first time Lagrangian) were deployed in the coastal regions of Swedish Baltic waters. From 2009 to 2011, an as-

semblage of 69 chambers was used for direct flux measurements between 0.5 m and 75 meter depth.

Sea-to-air fluxes determined at water depths from 3 to 75 m in June 2011 and October 2011 ranged from 0.01 to

0.12 mmol CH4 m-2

d-1

with an average of 0.06 ± 0.007 mmol CH4 m-2

d-1

(Fig. 23). Methane fluxes decreased

slightly with water depth. The highest flux was obtained from additional 24-hour measurements at the edge of

densely vegetated shore areas in only 0.5 meter water depth. Here the fluxes were as high as 0.57 mmol m-2

d-1

.

Bubble shield experiments at four shallow sites in depths less than 5 meters were conducted to separate diffu-

sive and bubble fluxes. These experiments indicated that between 30% and 84% of the total flux could be at-

tributed to bubbles. Inshore measurements in the eutrophic inner Himmerfjärden revealed clear methane sur-

face maxima, which are likely due to discharge of methane from a local sewage treatment. These concentrations

Fig. 22. Methane surface concentrations between Lübeck and Helsinki in 2010 along all transects passing close to the west of east of the Island of Gotland color-coded for each individual month.

25

Fig. 23. Sea-to-air methane fluxes (mmol m-2 d-1) at three localities Himmerfjärden, Hållsviken, and Tvären, respectively in the southern Stockholm archipelago. Chamber derived measurement were performed in June and October 2011.

were significantly higher than concentrations measured in bottom waters over a whole summer-fall measuring

campaign and suggest that a significant part of the methane in this area is not derived from benthic emissions,

but of sewage origin.

Of particular interest was the finding that the efficiency of methane oxidation above the deep anoxic basins of

the archipelago sea was very high. The deep water in these basins had methane concentrations as high as 644

nM, but more than 98% of this methane was oxidized at the chemocline and in the oxic water column above

resulting in very low emissions to the atmosphere.

Based on our data, we conclude that the inshore zone has methane emissions that are an order of magnitude

higher than in the open waters of the Baltic Sea. Of these emissions, the littoral zone with water depths less than

8 meters emits a significant part of methane in the form of bubbles. Since the littoral area is the most critically

affected zone by nutrient runoff and groundwater discharge, future work must concentrate on the littoral to

improve our predictions for future methane emissions.

Tvären transect

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Tväre

n 1

Tväre

n 2

Tväre

n 3

Tväre

n 4

Tväre

n 5

Tväre

n 6M

etha

ne fl

ux (

mm

ol/m

2 /d)

Oct-11Jun-11

Hållsviken transect

0.00

0.03

0.06

0.09

0.12

0.15

Hållsviken1

Hållsviken2

Hållsviken3

B1Met

hane

flux

(m

mol

/m2 /d

)

Oct-11Jun-11

Himmerfjärden transect

0.00

0.02

0.04

0.06

0.08

0.10

0.12

H6

SIVAB H5

Frinsö H4 H3 H2M

etha

ne fl

ux (

mm

ol/m

2 /d)

Oct-11Jun-11

Himmerfjärden

Hållsviken

Tvären

Tvären transect

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Tväre

n 1

Tväre

n 2

Tväre

n 3

Tväre

n 4

Tväre

n 5

Tväre

n 6M

etha

ne fl

ux (

mm

ol/m

2 /d)

Oct-11Jun-11

Hållsviken transect

0.00

0.03

0.06

0.09

0.12

0.15

Hållsviken1

Hållsviken2

Hållsviken3

B1Met

hane

flux

(m

mol

/m2 /d

)

Oct-11Jun-11


0.00

0.02

0.04

0.06

0.08

0.10

0.12

H6

SIVAB H5

Frinsö H4 H3 H2M

etha

ne fl

ux (

mm

ol/m

2 /d)

Oct-11Jun-11


0.00

0.02

0.04

0.06

0.08

0.10

0.12

H6

SIVAB H5

Frinsö H4 H3 H2M

etha

ne fl

ux (

mm

ol/m

2 /d)

Oct-11Jun-11

Himmerfjärden

Hållsviken

Tvären

26

1.5 Modelling methane dynamics in the Baltic Sea

Shallow seismic data were important basic information for locating free methane in the Baltic Sea sediments. In

combination with physical/chemical parameters measured in sediment cores – in particular methane and sulfate

– BALTIC GAS scientists at Utrecht University (NL) established models which were able to couple a large array of

user-defined geochemical reactions to transport processes which affected aqueous and/or solid species. The

modeling performed for BALTIC GAS was based on the Biogeochemical Reaction Network Simulator (BRNS) de-

veloped by Regnier and co-workers and made available to the public through the BALTIC GAS homepage at

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp5-deliverable-1/ (see also Deliverable 5.1). Here,

the user can access the model and define which chemical species, reactions, transport processes, and spatio-

temporal domain is to be used. Although the model can be adapted to variable boundary conditions, grids, and

highly-complex reaction equations, these features require additional manipulation of the model code which can

be performed by the scientists involved in the project. Several examples of sediment modeling for the dynamics

of organic matter, sulfate and methane are shown below.

1.5.1 Climate-related effects on past and future methane dynamics

A transient reactive-transport model (Deliverable 5.1) was developed to study the evolution of the benthic me-

thane and sulfur cycles at the millennial and centennial timescales. The overarching goal of the research was (1)

to reconstruct the evolution of methane turnover rates as a result of long-term changes in climate conditions

over glacial-interglacial cycles (Holocene period, 104 year timescale) and (2) to predict whether future climate-

dependent changes in temperature and ventilation of the Baltic Sea, combined with continued organic carbon

loading, could enhance methane gas production and release from the seabed (Deliverable 5.2).

1.5.1.1 Hindcasting methane dynamics during the Holocene period

The model was used to track the development of the methane geochemistry following the deposition and deg-

radation of organic rich sediments. This process was initiated 8,000 years ago when the Baltic Sea changed from

a freshwater system to a brackish system due to the rising sea level and a connection to the North Sea (the Litto-

rina Sea stage of the Baltic Sea). By simulating the sedimentary history of the methane cycle since its inception,

the required timescales for the development of a methanogenic zone and for free gas formation in Baltic Sea

sediments was reconstructed. Figure 24 shows the benthic biogeochemical dynamics near the center of the Ar-

Fig. 24. Development in particulate organic carbon (POC, i.e organic matter deposition; brown line), sulfate (SO4

2-; blue line), dissolved methane (CH4(aq); red line), and free methane gas (gray shaded curve) in Baltic Sea sediment (Arcona Basin) starting 8,000 years before present (BP) when the environment gradually turned brackish. The maximum depth penetration of POC (vertical brown line) equals the thickness of the Holocene mud layer. An example from the Arkona Basin modelled by use of a reactive transport model coupling solid-aqueous-gas dynamics.

27

kona Basin as an example. Simulations revealed that sulfate diffusion and sulfate-reduction controlled the fate

of organic matter during the first 3 kyr of the Littorina Sea stage. Thereafter, organic carbon degradation ex-

ceeded the rate at which sulfate was transported to the deeper sediment layers and methanogenesis occurred.

Almost concomitantly, anaerobic oxidation of methane began to consume the sulfate diffusing down from above

the methanogenic zone and also the residual sulfate pool within the glacial sediment below the muddy layer.

Consequently, the sulfate-methane transition shoaled upwards towards the sediment-water interface. A further

3 kyr until 1.6 kyr BP were required for the dissolved methane to reach the in situ solubility limit and form free

methane gas. Over the last 2 kyrs, the gas volume fraction increased to reach a contemporary concentration of

about 5 % by volume. Repeating such simulations at selected locations in the basin has also allowed to delineate

the zones where aqueous and gaseous methane are present and to construct a basin-scale methane budget.

1.5.1.2 Forecasting the impact of climate change on methane gas inventories

A reactive-transport model, which accounts for the effect of climate change on the productivity, bottom-water

temperature and salinity of the Baltic Sea, has been applied to forecast the evolution of the seafloor methane

gas inventory (Fig. 25). Full transient simulations were performed for the period 2010-2110, using boundary

conditions extracted from a 3-dimensional ecosystem model of the Baltic Sea3 forced by a regional dataset of

greenhouse gas emissions (IPCC scenario A1B).

The results obtained for the Arhus Bay transect

reveal that the temperature rise of circa 1.8 de-

grees predicted for the period 2010-2100 could

trigger a significant increase in gaseous methane

inventory, move the gas front closer to the

ment-water interface and lead to the formation of

gas at stations where there currently is none (sta-

tion M26). Similar results have been obtained in

shallow sediments of the Bothnian Bay, where gas

production is enhanced by the combined effects

of temperature and decrease in bottom-water

sulfate induced by the freshening of Baltic Sea.

Altogether, these factors could favor methane

release from the seabed, although this remains

essentially unknown. In the example below from

Aarhus Bay, model results reveal that if gas mi-

grates upwards through the sediment, most (if not

all) of this gaseous methane is concurrently re-

dissolved and oxidized during transit towards the

sediment-water interface. This gas movement

should theoretically occur if the gas pressure ex-

ceeds the pore throat entry pressure but is not

sufficiently high to fracture the sediment. No gas

fractures were observed in the sediment, and

neither was gas escape into the water column. The

exact mechanisms of gas advection and dissolu-

3 Neumann, T. (2010) Journal of Marine Systems, 81, 213-24

Fig. 25. Concentration profiles of sulfate, methane and methane gas at 4 stations in Aarhus Bay with increasing mud thickness denoted by the horizontal line (see also Fig. 16 and 17). The stations are approximately 50 m apart. The sulfate-methane transition is indicated by the gray shaded band. The top panels represent the present day (steady state) situation, and the lower panels are those where the model is run for 100 yr imposing a +0.018 oC yr-1 change in temperature in the bottom water.

28

tion remain uncertain and prediction of how gas migration will respond to future environmental and climate

changes (e.g. through the onset of sediment fracturing) remains similarly uncertain (Deliveable 3.2). Sensitivity

studies show that the methane flux (aqueous + gaseous) to the water column forecasted for the year 2100 is

highly dependent to the controlling processes, with high advection rates and/or slow dissolution rates promot-

ing the propensity for methane escape (results not shown). The model results represent the first data-

supported predictions of future methane fluxes in the Baltic Sea. Yet, further research in this area is essential for

a more accurate forecasting of the role of Baltic Sea sediments to green-house gas emission and thereby to cli-

mate-induced warming.

1.5.2 Environmental controls on gaseous methane production in the Baltic Sea (an example from Aarhus Bay)

The methane dynamics in the Baltic Sea are closely related to the deposition and build–up of an organic–rich

marine mud layer which began around 8 kyr ago as a result of rising sea level and brackish-water inundation of

the Baltic Sea that we know of today. This Holocene mud overlays organic–poor silty sediments deposited under

freshwater of glacial origin. Because of the uneven topography at the upper fringe of the freshwater sediment,

the thickness of the overlying marine mud deposits is often highly variable. Numerous seismic observations

throughout the Baltic Sea reveal that the formation of methane gas only occurs once a critical mud thickness is

surpassed. As an example, a seismic profile from Aarhus Bay at the entrance to the Baltic Sea is shown in Fig. 16

and illustrates that the appearance of free methane gas in this case occurs where the mud layer exceeds about

10 m. Yet, this depth is not fixed, but varies over Aarhus Bay and over the Baltic Sea in general. Reactive-

transport modeling was applied to (1) identify the main controls of methanogenesis and gas formation in the

seabed and (2) derive a mechanistic explanation for the abrupt appearance of gas when a critical mud thickness

is reached. The study area covered a mud lens in Aarhus Bay (Denmark), sampled for concentrations and rates at

7 stations along a transect characterized by increasingly thicker Holocene mud (Fig. 16).

Numerical simulations show that the main trigger for gas formation is the bulk sediment accumulation rate asso-

ciated with increasing mud thickness. High accumulation rates dilute the organic material deposited on the sea

floor with inorganic material and lead to a more rapid burial of reactive organic matter down into the methano-

genic zone, with resulting higher rates of methano-

genesis as well as gas production. This is illustrated

in Fig. 25 (upper panel), where the sedimentation

rate increases from 110 cm kyr-1

at station M25 to

152 cm kyr-1

at station M28 and where gas forms

when the mud thickness becomes larger than ̴10

m (station M27). The model captures also the posi-

tion of the gas layer, the so called Free Gas Depth

(FGD) corresponding to the uppermost depth

where gas first occurs, by allowing methane gas to

advect upwards through the sediment. If the gas

did not move but instead remained in situ, a hypo-

thetical simulation from site M29 shows that the

FGD would not rise above 850 cm and the simulat-

ed sulfate penetration depth would be about one

meter deeper than observed (Fig. 26a,b). Gas ad-

vection is accompanied by gas dissolution in the

Fig. 26. Simulated (curves) and measured (symbols) pore water concentrations and free gas volumes at station M29 (see Fig. 17). (a) Without allowing for gas advection through the sediment, (b) with gas advection, (c) δ13C isotopic distributions of dissolved inorganic carbon without gas advection and (d) δ13C isotopic distributions of dis-solved inorganic carbon with gas advection. The gray band indicates the sulfate-methane transition zone (SMTZ) pre-dicted by the model.

29

zone of Anaerobic Oxidation of Methane (AOM). Since this process consumes dissolved methane and is the

prime cause for bringing the methane concentration down below saturation, AOM can be likened to a geochem-

ical barrier for gas escape. Modeling of stable carbon isotope distributions support further the hypothesis that

methane gas advection and dissolution occur in the AOM zone (Fig. 26d). Without this mechanism, the AOM

rates would be significantly lower and would lead to simulated δ13

C isotopic distributions that were significantly

heavier (less negative) than the measured values (Fig. 26c). The suite of data and model results are nevertheless

consistent with the idea that all the methane transported by diffusion and gas migration is ultimately consumed

by AOM, and consequently only minor or no methane currently escapes to the ocean–atmosphere (Deliverable

5.3).

1.5.3 Regionalization and budgeting of methane cycle In sediments of the Baltic Sea high concentrations of methane (CH4) were observed by biogeochemical as well as

geophysical investigations. Biogeochemical investigations were based on sediment and pore water sampling at

selected sites and subsequent chemical and microbiological analyses. This provided detailed information about

the production and fate of biogenic methane, generated by microbially mediated processes, as well as the po-

tential release of this greenhouse gas into the water column. Geophysical methods like shallow seismic surveys

provided new information about the spatial distribution of free gas (methane gas bubbles) in sediments.

Data derived by biogeochemical or geophysical studies provided very detailed information for selected sites as

well as along survey lines. Nevertheless, the spatial coverage of these studies was – due to the time consuming

and costly techniques – rather sparse. For considerations of large scale spatial patterns and budgets, a combina-

tion of elaborate, site specific measurements with geophysical data on forcing factors which are available with

sufficient spatial coverage, are required. This supports the computation of methane budgets as well as identifi-

cation of regions where high or low methane concentrations are expected.

For spatial modeling, forcing factors like the accumulation rate of particulate organic matter (POC), the POC-

content, bottom water concentrations of e.g. sulfate and oxygen, bathymetry, slope, morphological units, bot-

tom water temperature, and current speed as well as indicators for methane formation like pockmarks were

considered. All data were projected and combined applying the Lambert azimuthal equal-area projection and

using similar grid size. By statistical analysis we compared the former mentioned parameters for regions where

free gas was observed with regions in the surrounding where free gas was not observed (Fig. 27). The spatial

modeling was applied for the different sub-regions of the Baltic Sea. For each region, a set of factors was derived

that are likely to contribute to the formation of free gas. These factors were iteratively improved and applied to

compute predictive maps about the spatial distribution and the total area of free gas in sediments of the Baltic

Sea (Fig. 28).

30

Fig. 27. (A) Locations in the Baltic Sea where free gas were observed in surface sediments (red polygons). For spatial analysis POC (i.e. particulate organic carbon) accumulation rates (B) or oxygen concentrations in bottom water (C) were considered as forcing factors. From statistical analysis of forcing factors related to the formation of free gas in surface sediments weighting coefficients were derived.

31

1.6 Deliverables

WP1.1: BALTIC GAS web-page

www.balticgas.au.dk (Bo Barker Jørgensen, Henrik Fossing)

WP1.2: Scientific reports (Y1, Y2, final)

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp1-deliverable-no-2-scientific- reports/

(Bo Barker Jørgensen, Henrik Fossing)

WP1.3: BALTIC GAS Workshops and meetings (reports)

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp1-deliverable-no-3-baltic-gas-workshops-and-

meetings-reports/ (Bo Barker Jørgensen, Henrik Fossing)

WP1.4: Submission of data to a common database

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp1-deliverable-no-4-submission-of-data-to-a-

common-database/ (Bo Barker Jørgensen, Henrik Fossing)

Fig. 28. Spatial distributing of free gas (modeled) in Baltic Sea (except Gulf of Bothnia and Finland) showing the proba-bility to find free gas in surface sediments. The prediction is based on analyses of parameters like particulate organic carbon (POC) accumulation, O2 and SO4

2- concentration in bottom water as well sediment type, observed within known free gas areas. The data set was factorized to obtain a prediction for the occurrence of free gas areas within the Baltic Sea. This procedure was optimized by comparison of the similarity of the spatial distribution of known free gas and predicted free gas areas. Based on this comparison predicted probability levels of gas occurrence (low, medium-low, medium, high) were assigned.

32

WP1.5: Research cruises

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp1-deliverable-no-5-research-cruises/

(Bo Barker Jørgensen, Henrik Fossing)

WP2.1: GIS-map of mined data

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp2-deliverable-no-1-gis-map-of-mined-data/ (Jørn B.

Jensen, Bo Barker Jørgensen)

WP2.2: GIS-map of methane flux and distribution in sediments

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp2-deliverable-no-2-gis-map-of-methane-flux-and-

distribution-in-sediments/ (Michael Schlüter, Torben Gentz, Roi Martinez, Jørn B. Jensen, Laura Lapham)

WP2.3: GIS-map of hot-spots of present and future CH4-emission

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp2-deliverable-no-3-gis-map-of-hot-spots-of-

present-and-future-ch4-emmission/ (Michael Schlüter, Torben Gentz, Roi Martinez)

WP3.1: Mapping of shallow gas and physical characterisation of gas-bearing sediments

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp3-deliverable-no-1-mapping-of-shallow-gas-and-

physical-characterisation-of-gas-bearing-sediments/ (Jørn B. Jensen, Rudolf Endler)

WP3.2: Identification of zones of potential weakness

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp3-deliverable-no-2-identification-of-zones-of-

potential-weakness/ (Gregor Rehder, B.B. Jørgensen)

WP3.3: Detection and monitoring of methane ebullition

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp3-deliverable-no-3-detection-and-monitoring-of-

methane-ebullition/ (Jens Schneider v. Deimling, Wanda Gülzow, Marina Ulyanova, Zygmunt Klusek, Gregor

Rehder)

WP4.1: Methane distributions and breakdown

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp4-deliverable-no-1-methane-distributions-and-

breakdown/ (Timothy G. Ferdelman, Volker Brüchert, Sabine Flury, Henrik Fossing, Bo Barker Jørgensen, Laura

Lapham, Nikolay Pimenov, Maja Reinholdsson, Nguyen M. Thang)

WP4.2: Methane emission through sediment-water and sea-air interfaces

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp4-deliverable-no-2-methane-emission-through-

sediment-water-and-sea-air-interfaces/ (Volker Brüchert, Timothy G. Ferdelman, Henrik Fossing, Wanda Gülzow,

Laura Lapham, Gregor Rehder, Nguyen Thanh Manh, Jens Schneider von Deimling, Torben Gentz, Michael

Schlüter)

WP4.3: Holocene evolution of the Baltic Sea ecosystem

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp4-deliverable-no-3-holocene-evolution-of-the-

baltic-sea-ecosystem/ (Daniel Conley, Maja Reinholdsson, Conny Lenz, Lovisa Zillén)

WP4.4: Submitted MS on: Sulphur and methane biogeochemistry

Flury, S., A.W. Dale, H. Røy, H. Fossing, J.B. Jensen, B.B. Jørgensen (submitted) Methane fluxes and shallow gas

formation controlled by Holocene mud thickness in Baltic Sea sediments. Geochimica et Cosmochimica Acta

WP5.1: Transport/ reaction models reg. methane and sulphur dynamics

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp5-deliverable-1/ (José Mogollón and Pierre Reg-

nier)

33

WP5.2: Predictive model and climate change scenarios

http://balticgas.au.dk/balticgasaudk/project/deliverables/wp5-deliverable-no-2-predictive-model-and-climate-

change-scenarios/ (Pierre Regnier and Andy Dale)

WP5.3: Submitted MS on: Integration gas, acoustics and biogeochemistry

Dale, A.W., S. Flury, P. Regnier, H. Røy, H. Fossing, B.B. Jørgensen (submitted) Coupling between methanogene-

sis, anaerobic oxidation of methane and δ13C distributions in gassy sediments from the Baltic Sea (Aarhus Bay).

Geochimica et Cosmochimica Acta

2. Further research and exploitation of the results

2.1. Further research

BALTIC GAS has generated a large and high-quality dataset for the distribution and dynamics of methane, proba-

bly the most comprehensive methane dataset for any marginal sea. This has been possible through the acquisi-

tion of new data during the many research cruises and through the mining of existing data. The information was

compiled in GIS maps that provide geographical overviews and information on the parameters controlling me-

thane accumulation and turnover. Such GIS maps are based on our current understanding of statistical and

causal relationships between sediment properties, water quality, and microbial processes. The GIS maps should

be considered as dynamic, however, and will be improved as further data become available or as the algorithms

for the calculation of derived properties are adjusted.

Researchers of the BALTIC GAS project have combined seismo-acoustic mapping of gas distribution and sedi-

mentology with biogeochemical point analyses. An important verification and quality control of the developed

GIS maps is therefore a further targeted core sampling and analysis to check the properties predicted by the GIS

algorithms. Key areas for such verification include the Bornholm Basin in which the latest interpretation phase

has shown that it is possible to map late Holocene subunits like the Medieval Warm Period and the Little Ice Age.

Future research would be able to focus on such Holocene time intervals and investigate methane production

and flux in these intervals.

Due to the limited capacity of BALTIC GAS, the project focused on the main sedimentary basins in the Baltic Sea

where most methane is supposedly generated. The coastal zone is, however, much more dynamic and is also

much more sensitive to local effects such as sewage outlets (e.g. Himmerfjärden) or river outlets (e.g. Bay of

Gdansk). Our data from the Swedish archipelago indicate that the coastal zone methane emission to the atmos-

phere may be ten-fold higher than in the central Baltic Sea where most studies were done. Information on the

source strength of the coastal zone for the overall emission of methane is therefore needed in order to develop

a methane budget for the entire Baltic Sea. In this respect data are largely lacking for the Bothnian Gulf (i.e.

Bothnian Sea and Bay) and in the Gulf of Finland compared to the southern part of the Baltic Sea. Future moni-

toring of methane requires the installation of more ship-based and coast-based continuous measurement sys-

tems to extend areal and temporal coverage.

As a part of BALTIC GAS we searched for point sources of gas ebullition and for sediment structures (pockmarks)

as indicators for such ebullition. The project reached the conclusion that pockmark areas are rather few and that

34

the continuous outgassing from such point sources is negligible in the overall methane budget. The project was,

however, not able to monitor potential large scale and diffuse outgassing that may take place during extreme

weather conditions such as low water level or storms, particularly at more shallow waters where also waves

might induce a pumping effect on the seabed. There are undocumented observations that such transient out-

gassing indeed takes place in some areas of the Baltic Sea where gas bubbles have accumulated at shallow depth

in the seabed. The temporal dynamics of methane cycling are therefore important. These may in the future be

monitored by measuring buoys that are positioned in strategic areas and are equipped with the instrumentation

for continuous methane analysis.

BALTIC GAS focused on only one of the important natural green-house gases, methane. Other trace gases, such

as nitrous oxide or dimethyl sulfide, may also be important and are known to be emitted in particular from the

coastal zone. Future Baltic Sea research should include this highly dynamic zone which presumably constitutes a

belt of high natural green-house gas emission all around the Baltic Sea.

Finally, we have not addressed which influence dredging, trawling or construction activity has on the biogeo-

chemistry of Baltic Sea sediments and their ecosystems. How much of the Baltic Sea seafloor is turned over and

what does this mean for the Baltic Sea are critical questions in the Anthropocene.

2.2. Exploitation of the results

With the end of the BALTIC GAS project the scientific exploitation of the results is by far not ended. A vast

amount of new acoustic data has been gathered, and though the processing has been mostly finalized within the

project’s time frame, data interpretation is by far not complete. Currently, at the end of the project, analysis of,

e.g. the multi-frequency data set of the Bornholm basin will continue with the aim to quantify the free gas oc-

currence in this area. The new methodological approach uses low frequency multibeam backscatter data able to

penetrate the seafloor down to 10 m and very precisely define the depth of the ‘acoustic gas front’ within this

range. This approach to map the 3-D distribution of free gas in shallow sediments has enormous potential as a

tool for seafloor monitoring prior to offshore constructions, i.e. wind farms or pipelines.

Two other new and promising seismo-acoustic techniques were developed during BALTIC GAS and demonstrat-

ed major scientific progress in quantification of gas distribution and gas volume in marine sediments. For the

first time, BALTIC GAS scientists were able to quantify the volume of free gas in marine sediments by monitoring

methane gas bubble resonance with a Parasound sediment echo-sounder at 4.2, 18.5 and 42.8 kHz. By use of a

new algorithm the signal was transformed to a gas volume of 0.1 – 2% in the Bornholm Basin test area. Further-

more, the technique enabled for the first time the mapping of the lower boundary of gas and thereby opened

the possibility to determine the total quantity of gas in the entire sediment column.

A novel application of a multibeam swath mapping system for sediment visualization was developed to detect

and quantify gas bubbles rising from the seabed. A new cross-correlation technique similar to that used in parti-

cle imaging velocimetry has yielded impressive results with respect to unambiguous bubble detection and re-

mote bubble rise velocimetry and thus presents a new tool for future mapping of gas ebullition through the

water column.

35

The pore water and solid phase data collected in the muddy regions of the Baltic Sea will serve a baseline for

sediment biogeochemistry in the Baltic. These chemical data have been used and will continue to be used to

constrain the reservoirs of dissolved methane and hydrogen sulfide in Baltic Sea sediments. The mapped depths

of the sulfate-methane transition will serve to identify areas where free methane gas and associated high con-

centrations of reactive hydrogen sulfide exist near the surface. For the purposes of planning human activities,

e.g. the placement of structures, dredging, and/or fishing, at or near the seafloor, these maps and distributions

will serve to identify zones where gas may be problematic (e.g. due to sulfide corrosion).

The comprehensive database compiled for methane and other geochemical key parameters in the Baltic Sea

provides highly valuable environmental information for this sensitive ecosystem. The data have been submitted

to the database, PANGAEA, which refers to the World Data Center for Marine Environmental Sciences, hosted

and maintained at the Alfred Wegener Institute for Marine and Polar Sciences. The valuable data are thereby

secured for public access and are open to targeted data search by all scientists and environmental authorities. A

moratorium on new and still unpublished data has, in agreement with the participating scientists, been limited

to two years after the end of BALTIC GAS.

The webpage of BALTIC GAS (www.balticgas.net) will be maintained and continue to provide extensive and edu-

cational information on the principles of methane cycling and the past and future methane dynamics in the Bal-

tic Sea. Similarly, compiled data in the form of GIS maps will be available through this webpage. Finally, the

webpage links to a reactive-transport model which was developed by the University of Utrecht and which is

available for external users to model their scientific data.

The BALTIC GAS project has had an important component of basic science. Among the primary objectives has

been to understand the controls on the modern methane cycle and potential hotspots of methane emission. The

project reached important milestones towards these objectives and can now present realistic forecasts of me-

thane production and accumulation under different scenarios of climate change and eutrophication. The main

results of these achievements will become available to the public in the form of publications in the international

scientific literature and through popular articles and press information.

Last but not least, BALTIC GAS successfully promoted the collaboration among scientists from different Baltic

countries and from different disciplines, in particular with key expertise in geophysics and biogeochemistry. The

project also trained many students and young scientists in these fields. The joint efforts allow interdisciplinary

approaches for the interpretation and interpolation of biogeochemical measurements by using geophysical

maps. In this respect, the network of scientists established within the project is a sustainable achievement,

which will result in continued collaboration and joint proposals far beyond the finalization of BALTIC GAS.

36

3. Work package overview

WP 1: Project management, coordination and dissemination (reported by Henrik Fossing, National Environmental Research and Bo Barker Jørgensen, Center for Geomicrobiology, both at Aarhus University, Denmark)

Task 1.1: Management and dissemination 1.1.1: Coordination scientific Reports 1.1.2: Organizing Workshops or Meetings 1.1.3: Establishment of project home-page

Task 1.2: Submission of data to a common database

Task 1.3: Research cruises 1.3.1: Identification of target sites 1.3.2: GIS based maps of target areas 1.3.3: Organizing two weeks cruises

Task 1.4: Ph.D-training program

Deliverables due within this reporting period:

1.2 Scientific reports (Y1, Y2, final)

1.3 BALTIC GAS Workshops and meetings (reports)

1.4 Submission of data to a common database

1.5 Research cruises

Task 1.1: Management and dissemination

The coordinators have discussed the outcome of BALTIC GAS with all WP-leaders, Principal Scientists and Task

Responsibles and express that

− all WPs and Tasks have been accomplished according to original research and financial plan,

− no adaptation of the research plan and schedule of deliverables was done during the project.

During the third project year two BALTIC GAS-workshop were organized, the first in cooperation with the hosting

institution: Shirshov Institute of Oceanology, Atlantic Branch, Russian Academy of Sciences, Kaliningrad-region,

Russia (February 23-24) – the second organized by the coordinators at Department of Biological Sciences, Aarhus

University (November 1-3). Meeting reports with agenda and minutes from these workshops are accessible from

the BALTIC GAS home-page (http://balticgas.au.dk/).

Task 1.2: Submission of data to a common database

BALTIC GAS scientists have uploaded data of primarily biogeochemical nature to the PANGAEA database

(http://pangaea.de) rather than SeaDataNet in compliance with the BONUS Steering Committee. Importantly, by

using PANGAEA we ensure that not only metadata but also the original data are stored and maintained on the

long term in an open database. To ensure a reproducible format in all data sets delivered to the data base and

thus facilitate data delivery to PANGAEA a ‘data manger’ (Henrik Fossing, Aarhus University) was appointed. The

data manger receives, coordinates, and keeps track of the delivery of data from the Baltic Gas scientific commu-

nity to PANGAEA. These data are easily accessible from the PANGAEA-data base by an ‘advanced search’ for

project: BALTIC GAS. However, data from analyses not presently accomplished and data not having passed the

final ‘quality control’ will be added the PANGAEA data bases when ready.

Task 1.3: Research cruises

Two research cruises with BALTIC GAS participation have been performed during 2011 both organized by BALTIC

GAS institutions:

37

− RV Limanda (June 10 - 16) Field study campaign to Himmerfjärden. BALTIC GAS-cruise. Chief Scientist:

Volker Brüchert, Department of Geology and Geochemistry, Stockholm University, Sweden. 5 partici-

pants/ 2 BALTIC GAS institutions

− RV Limanda (October 20 - 21) Field study campaign to Himmerfjärden. BALTIC GAS-cruise. Chief Scien-

tist: Volker Brüchert, Department of Geology and Geochemistry, Stockholm University, Sweden. 2 par-

ticipants/ 1 BALTIC GAS institution

A brief summary of the two research cruises incl. published cruise reports are available at the BALTIC GAS

webpage http://balticgas.au.dk/balticgasaudk/project/workingareasandcruises/. Here you also find the cruise

reports from the 13 other cruises to the Baltic Sea performed during BALTIC GAS (see also Table 2 in Executive

Summary and The Y1 and Y2 BALTIC GAS scientific Reports (Deliverable 1.2) for further details.

Task 1.4: Ph.D-training program

A total of 7 PhD and 2 Master students received the major part of their educational training during BALTIC GAS

of which one students graduated during 2011 and the rest will give in the thesis/ dissertation during the next

two years. Educational activities comprised i.a. participation in workshops and research cruises where the stu-

dents depending on their educational field took part in seismo-acoustic imaging, sediment coring and sampling,

chemical analyses, biogeochemical process analyses, and modeling. For further details see 5. Educational activi-

ties below).

Additionally in 2010 a training BONUS-course Seismo-acoustic Imaging of Sedimentary and Gas-related Features

in the Baltic Sea organized by University of Bremen and University of Szczecin took place in the Malkocin Confer-

ence Center of the University of Szczecin (Poland) and on board M/V Nawigator XXI between15-27 July, 2010

(see The Y2 BALTIC GAS scientific Report and ‘cruise report,

http://balticgas.au.dk/balticgasaudk/workshopsandcourses/ further details).

WP 2: Data mining and GIS-mapping (reported by Jørn Bo Jensen, Geological Survey of Denmark and Greenland, Denmark)

Task 2.1: Data mining 2.1.1: Searching Baltic Sea methane data in national data-bases 2.1.2: Compiling data in a common database

Task 2.2: GIS-mapping 2.2.1: Mapping of mined data 2.2.2: Mapping of methane flux and distribution in sediments 2.2.3: Mapping of hot-spots of present and future CH4-emission

Deliverables due within this reporting period:

2.1 GIS-map of mined data

2.2 GIS-map of methane flux and distribution in sediments

2.3 GIS-map of hot-spots of present and future CH4-emission

Task 2.1: Data mining

Data mining was a two phase process starting with search of mainly seismic data within and outside the project

partners, as well as additional alternative data types, such as organic contents in samples, sediment distribution

maps and maps of Holocene sediment thickness. The collected project seismic data and archive data were com-

piled in a common database and the seismic data has been interpreted in a seismic workstation.

38

2.1.1 Searching Baltic Sea methane data in national data-bases

Data mining was done within and outside the project partners (i.e. BALTIC GAS institutions) and was as such

divided into two categories.

Data mining within the project partners included, besides the already mapped areas (Metrol project gas map-

ping (Laier and Jensen 2007)4) in the Danish sector, data from IOW’s and RAS’s archives. IOW data included in

the first step the Mecklenburg Bay, Arkona Basin and Bornholm Basin and in these areas no additional data from

‘outside’ was required, but data collected during the BALTIC GAS project was included as well. Additional data

from the IOW-archive covered parts of the Polish Stolpe Forchannel and Gdansk Bay as well as data from the

Gotland Deep. The Russian sector offshore Kaliningrad was covered by archive data from RAS and the methane

distribution in this region was mapped by RAS as well.

Data mining from outside the project partners was more difficult than expected. An inquiry among Baltic State

geological surveys revealed that search for seismic data and subsequently preparing and handing over these

data to BALTIC GAS comprise a workload that most geological surveys were not able to handle without addition-

al resources. These institutions were asked to estimate their costs for data handling but replies were unfortu-

nately lacking. Most promising was the responds from Swedish and Finnish institutions whereas seismic data

from the Polish Geological Survey was dropped as explained below.

The Swedish Geological Survey (SGU) was visited in May 2010 by TA Jørn Bo Jensen and SGU showed interest in

the project. SGU has like the rest of the Baltic Sea surveys no tradition of mapping the distribution of methane

gas in the seabed, but BALTIC GAS has been provided with detailed maps of Holocene clay distribution and sam-

pling positions containing free gas. This has been key data in estimation of the Baltic Sea methane distribution.

Tom Flodén, retired from The University of Stockholm, holds an extensive and scientific valuable database of

seismic data from the central Baltic Sea. Tom Flodén offered to share his data with BALTIC GAS and for a minor

cost he prepared his data for transfer to BALTIC GAS and mapped the methane distribution in the Baltic Sea

seabed in the offshore region between Gotland and Estonia.

The Geological Survey of Finland (GSF) has been addressed as a Bonus partner (i.e. Inflow) and has replied posi-

tive. Like SGU, GSF has not mapped methane in the seabed but Baltic Gas participated in the RV Aranda, April

21-28, 2009 cruise and was provided with available seismic data from the cruise.

The Polish Geological Survey (PGS) has been contacted in writing and asked for information about distribution of

methane in the Polish sector seabed. The official answer from PSG was that they could not supply information

free of charge. This implied that Baltic Gas would have to pay for interpreting the archived Polish data and sub-

sequent transfer to the project. However it was concluded that ‘mining‘ methane data from PSG would not con-

tribute significantly to the Baltic Gas database compared to data form the Polish seabed already available within

the Baltic Gas group (IOW archive data).

4 Laier, T. and J.B. Jensen (2007) Shallow gas depth-contour map of the Skagerrak-western Baltic Sea region. Geo-Mar Lett 27:127–

141.

39

In addition to the search in national databases a literature search was carried out in order to collect published

information on gas distribution in local areas, as example environmental studies in the Stockholm archipelago

and the Szczecin Lagoon, as well as scientific papers dealing with seismic studies and geochemical parameters.

Of special interest are GIS map compilation results from the EU BALANCE project (http://www.balance-eu.org)

that indicates the distribution of Holocene clay in relation to morphology types like valleys and basins. These

data has been provided from the GEUS GIS database.

2.1.2 Compiling data in a common database

Methane distribution data collected during Baltic Gas and ‘mined’ from the project partners were compiled at

GEUS, as basis for GIS-mapping carried out by AWI. The data base holds methane distribution data sampled by

Russian, German and Danish institutions and primarily covering the Baltic Sea sectors of these countries. The

collected seismic data has been loaded on a seismic workstation, the distribution of free gas has been digitised

and the data has been exported to GIS map presentation. Alternative information has likewise been geo-coded

and GIS maps have been compiled. The GIS themes are basic information for the GIS map compilations in WP 2

task 2.2.

Task 2.2: GIS-mapping

2.2.1: Mapping of mined data

GIS-mapping of mined data focused on the collection of basic map themes from the Baltic Sea like bathymetry,

economic zones, bottom water chemistry as well as the spatial distribution of pockmarks. In addition we inte-

grated data into the GeoInformation-System ArcGIS (ESRI) about sedimentology, seafloor properties like slope

angles or bottom water currents, as well as – from a process oriented and descriptive perspective – data sets

directly related to the presence or the formation of methane in surface sediments. The later includes free gas

areas observed by seismic surveys, known pockmark sites as well as gas flares released form the accumulation

rates of particulate organic matter were compiled and integrated into the GIS. The entire set of different param-

eters, geodata compiled within Task 2.1 as well as maps were georeferenced to a common map projection

(Equal Area Projections like the Albers projection), suitable for calculations of mass budgets.

2.2.2: Mapping of methane flux and distribution in sediments

For mapping of methane fluxes as well as the distribution of free gas in surface sediments the data derived with-

in Task 2.1, data measured by the BALTIC GAS partners during research cruises, information derived from seismic

lines as well as geochemical data derived from literature recherché were considered.

For aquatic environments like the Baltic Sea, the transition from the degradation of organic matter by microbial

mediated processes driven by agents like oxygen, nitrate or sulfate to the formation of methane by fermentation

is indicated by the sulfate-methane-transition-zone (SMTZ). Within the SMTZ the pore water concentration of

sulfate is entirely consumed by degradation of organic matter and re-oxidation of methane. Production of me-

thane is starting below the SMTZ. In the close vicinity to the SMTZ concentration gradients of sulfate and me-

thane are steep and well defined. From the perspective of biogeochemical analysis and sampling techniques, the

depth of the SMTZ can be well defined by pore water studies, whereas measurement of methane fluxes from

sediments into the water column or atmosphere are much more demanding. Therefore, the sediment depth of

the SMTZ provides a robust – in terms analytical accuracy and data availability- proxy for identification of regions

at the seafloor of the Baltic Sea where high or low methane production as well as fluxes of CH4 into the water

column are expected. For example, low SMTZ depths, suggesting high CH4 concentrations and fluxes into the

SMTZ, are mainly observed within mud sediment located in basins and valleys. In these regions the median value

40

of the SMTZ is about 0.2 m. For muddy sediments located in plains, a much wider range (0.2 to 2.2 m) and a

median depths of the SMTZ of about 0.6 m were derived.

Deliverable 2.2.3: Mapping of hot-spots of present and future CH4-emission

Regions where free gas within surface sediments or specific features like pockmarks or gas flares are observed

are hot-spots for present as and future methane emissions. Based on data derived in Task 2.1 and Task 2.2 as

well as contributions by the BalticGas partners, we integrated free gas region, pockmarks sites and sites where

gas flares were reported into the GIS.

Worldwide hot spots for methane formation and fluxes are observed. For examples, this includes (1) pockmarks

(morphological depression at the seafloor) where high methane concentrations were often detected, (2) gas

flares, where methane gas bubbles are released from the seabed, (3) shallow gas regions, where gas bubbles are

detected in close vicinity to the sediment-water interface as well as (4) chemo-autotrophic communities nour-

ished by upward fluxes of e.g. methane. Such hot spots are related to geological as well as environmental condi-

tions, favorable for formation of biogenic methane or the transport of thermogenic methane, produced within

deeper strata and transported along conduits to the sediment surface.

In close cooperation with the partners of the BALTIC GAS project, we compiled data about the spatial distribu-

tion of such hot spots for methane fluxes and integrated these information into the Geo-Information-System.

Especially in the western part of the Baltic Sea pockmarks and free gas areas were observed. In the eastern part

of the Baltic Sea pockmarks were detected in Gdansk Bay or the Gulf of Finland. For some of these sites, there

seems to be indications for thermogenic sources for methane. The GIS maps considering hot spots of methane

fluxes are intended to be applied by the BALTIC GAS partners as well as for the modeling of methane distribution

and fluxes.

WP 3: Gas and seismo-acoustic mapping (reported by Gregor Rehder, Baltic Sea Research Institute Warnemünde, Germany)

Task 3.1: Mapping and quantification of shallow gas by seismo-acoustic techniques

Task 3.2 Physical characterization of gas-bearing sediments

Task 3.3: Assessment of sites of sediment weakness for recent and future gas ebullition using multidiciplinary seismo-acoustic and sediment property data

Task 3.4: Detection and monitoring of gas bubble propagation through the water column and into the atmosphere in key regions of the Baltic

Deliverables due within this reporting period.

3.1 Mapping of shallow gas and physical characterisation of gas - bearing sediments

3.2 Identification of zones of potential weakness under the external forcing of climate change and eu-

trophication for future political and hazard prevention measures

3.3 Detection and monitoring of methane ebullition

A suite of new data has been gathered by scientific cruises organized by BALTIC GAS or with contribution from

partners of the BALTIC GAS consortium over the course of the project, involving both new acoustic (Task 3.1) as

well as sediment-physical data (Task 3.2). Additionally, existing knowledge on gas ebuillition in the Baltic was

compiled from literature and and scientific exchange with partners working in the Baltic, and extended by acous-

tic investigations seeking for gas emanating from the seafloor (Task 3.4).

41

Task 3.1: Mapping and quantification of shallow gas by seismo-acoustic techniques

Valuable seismic data (backed up with three gravity cores) were sampled in the Gulf of Finland and northern part

of Gotland deep during the Aranda-cruise (April 22-25, 2009). Also the annual student cruise of Bremen Universi-

ty with RV Alkor (cruise Al347 October 8 –18, 2009) in Mecklenburg Bay and Prorer Wiek (east of Rügen) was of

major relevance to the scientific scope of BALTIC GAS. Here, new multi-frequency seismoacoustic data were

collected for the mapping of gas in the shallow sediments by use of high-frequency seismic sources (i.e. airgun

and boomer) and an echo sounder system. Two cruises with RV Oceania were carried out as part of the collabo-

rative project BALTIC GAS from 20-27 February, 2009, and 05-15 November, 2009, respectively. Objectives of

these efforts were to collect acoustic (seismic) data in the areas with potential presence of shallow gas sedi-

ments, active gas seeping, and pockmarks. The near-bottom water column and seafloor was surveyed with hy-

dro-acoustic methods working in a broad frequency range. A sediment coring program took place during the

cruise in November. The cruise focused on the EEZ of Poland, including the fault system near the Smoldzino

Fault, the inner Gulf of Gdansk between Gdynia and Hel, and the Vistula River mouth. Acoustic data acquisition

included chirp data, 360 kHz multibeam data, and a dual frequency side scan sonar as well as other methods

During RV Poseidon cruise 392 (November 28 – December 17, 2009) seismo-acoustic data, long gravity cores as

well as undisturbed upper sedimentary cores, and hydrographic data in combination with dissolved methane

data from the water column were collected in the Mecklenburg Bay, Arkona Basin, Bornholm Basin and Gotland

Deep. The sampling program focused on gradients from gas underlain to gas-poor sediments along sections, and

to investigate the water column methane inventory along these sections. The hydrographic work also aimed for

across-basin sections of the methane distribution in a winter situation. The combination of older and new hy-

droacoustic data will help to assess the persistence of the shallow gas accumulations in Holocene sediments.

Single beam echosounder data (38, 200 kHz) in the Russian sector of the Baltic Sea, as well as in an area in Swe-

dish waters north of Gdansk Bay, were gathered during RV Professor Shtokman cruise 103 from June 20-27,

2010, and enabled a refinement of the areal extend of sediments underlain by shallow gas (~300 km2) and host-

ing pockmark structures (~1,7 km2) in the Russian sector.

The largest field expedition of the BALTIC GAS project, RV Maria S. Merian cruise MSM 16/1, covering nearly all

major basins (Arkona Basin, Bornholm Basin, Gotland Basin, Bothnian Bay and Bothnian Sea) took place from

July 30 to August 22. Acoustic data gathered comprise swath bathymetry data, multibeam backscatter data,

multi frequency single beam data (5-100 kHz), Parasound data as well as high frequency seismic data. The sedi-

ment acoustic work using the 5-100 kHz signal was focused in the western Baltic (Mecklenburg Bay, Arkona Ba-

sin and Bornholm Basin) on shallow gas hot spots, and reconnaissance surveys and detailed studies at new dis-

covered shallow gas hot spots were performed in the eastern Gotland Basin and northern Baltic Sea. Here, Para-

sound data were gathered simultaneously along all acoustic profiles. Extensive seismic data acquisition was fo-

cused on the known gassy part of the Bornholm Basin, as well as the Piltene depression west of the Gulf of Riga.

For seismic data acquisition two streamers in three different configurations were used in order to collect data

with high resolution and large offsets, necessary for precise imaging and quantification of shallow gas. In addi-

tion, a new method for spatial mapping of shallow gas using low frequency multibeam sonar backscatter signals

was demonstrated. The sediment acoustic records were used to select stations for water column and sediment

work during the cruise and the simultaneous recording of various systems will allow intercomparison of the re-

sponse of the different systems to the occurrence of shallow gas.

42

The annual student cruise of University of Bremen, R/V Alkor Al363, took place October 4 – 15, 2010, collecting

new multi-frequency seismo-acoustic data with the goal of completing the existing data sets imaging shallow gas

in the sediments. High spatial resolution surveys were carried out in the Mecklenburg Bay and the Arkona Basin.

Data were collected using high-frequency seismic sources (airgun, boomer), fan sweep bathymetric equipment,

and the echosounder system of the ship. Seismic lines were run along previous coring stations (from cruises

Gunnar Thorson Western Baltic 2004; Poseidon 392, 2009) where methane measurements were carried out on

samples from gravity cores, in order to investigate the geological controls on gas production. In addition, two

interesting pockmark areas in the Bay of Mecklenburg and in the Arkona Basin were surveyed in denser grids.

Fieldwork continued in 2011. A short cruise was fulfilled onboard a fishing vessel in August 25-26, in the Russian

sector of the south-eastern Baltic. Single beam echosounder (38, 200 kHz) was used for detailed study of the

pockmarks location area on the eastern slope of the Gdansk Deep as well as for the on-way bottom sediments

survey (total 137 nm).Two additional research cruises serving BalticGas took place on R/V Oceania from March

15 – 24 and September 18 – 28. Investigations were focused primarily in the Gdansk Basin, with special attention

on the Gdansk Deep pockmark area and the inner Gulf of Gdansk. The acoustic survey was extended to Slupsk

Bank/Slupsk Furrow area. The 12 kHz and CW/Chirp echosounders were mainly used to detect gas occurrence in

this regions (hydro-acoustic transect of sea bottom and water column). To confirm acoustical observations geo-

chemical sampling was performed (undisturbed upper sedimentary cores). Based on gathered information it was

possible to designate gas saturated sediments area including gas pocket areas and to determine the location of

gas pockmarks. Also, it was possible to observe gas outflows from one of the pockmarks east of Hel Peninsula,

where supplementary observations by 70,120 and 200 kHz echosounders have been performed.

The student cruise of University of Bremen in 2011 has been accomplished between 6-16 October on board R/V

Alkor (Al382) with focus on multi-frequency seismo-acoustic surveying. For the purpose of investigating the shal-

low gas content in the muddy areas of the Bay of Mecklenburg and East of Rügen, the existing seismo-acoustic

data were complemented with new profiles. High frequency sources (airgun, boomer), the ship’s multi-

frequency sediment echosounder, side scan sonar and multibeam echosounder were used.

Apart from these new data acquisition campaigns, major effort in 2011 was on the processing, compilation, and

interpretation of the data gathered over the course of the project. Multichannel seismic data collected on the

cruise MSM 16/1 in the Bornholm Basin, Gotland Deep, Bothnian Sea and Bothnian Bay, and on some of the

annual student cruises in the Bay of Mecklenburg and in the Arkona Basin were processed at the University of

Bremen during 2011. For the purpose of stratigraphical and structural interpretation, processing of seismic pro-

files followed a conventional data processing flow with special emphasis on the velocity analysis. Parasound

sediment echosounder data recorded at three frequencies were loaded into an interpretation software along

with the seismic profiles. In order to quantify the shallow gas content in the sediment, seismic attributes were

analyzed in detail.

The seismic data collected during the Baltic Gas project has been loaded on a seismic workstation and combined

with seismic archive data collected under WP2. The seismic dataset has been interpreted and combined with

additional seabed data information to present a GIS map of gas distribution in the Baltic Sea.

Task 3.2: Physical characterization of gas-bearing sediments

This task is mainly based on the extremely successful coring program performed during the expeditions POS 392

and MSM 16/1 (see Task 3.1). The full core MSCL-loggings of all cores intended for physical property analyses are

finished. The split core logging, core description, subsampling and selected sedimentological analyses were final-

43

ized in 2011. Core by core the data were compiled, calibrated, and processed. The data are used for geo acoustic

models and the interpretation of the seismo-acoustic records. At IOW, the physical properties and geoacoustic

data provide input to the development of a geoacoustic model based on the BIOT/STOLL theory for gas free and

gas charged sediments. Further questions investigated based on the physical properties data in combination

with the acoustics are the influence of gas bubble on the acoustic properties and on the strength of the muddy

sediments, the latter also contributing to Deliverable 3.2.

Task 3.3: Assessment of sites of sediment weakness for recent and future gas ebullition using multidiciplinary

seismo-acoustic and sediment property data

This task is an end-deliverable of the project and was based on the mapping of shallow gas occurrences and sites

of current methane ebullition. During brainstorming sessions at various of the semiannual Baltic Gas meetings, it

was discussed to use the model efforts within the project to further constrain future zones of weakness based

on diagenetic models using external forcing parameters mimicking projected changes (i.e. eutrophication, warm-

ing etc.), which has been further addressed for the assessment of future scenarios as treated in Deliverable 5.2.

The general limited risk of strong gas ebullition from the shallow methanogenic sediment in the Baltic is docu-

mented in Deliverable 3.3.

Task 3.4: Detection and monitoring of gas bubble propagation through the water column and into the atmos-

phere in key regions of the Baltic

During RV Poseidon cruise 392, a prototype of a water column imaging (WCI) multibeam system (50 kHz, ELAC)

was used for the first time to monitor free gas bubbles in the water column. It was possible to demonstrate the

potential to visualize seep-related gas release occurring during deployment of instruments on the seafloor. This

part of the program is a major technological breakthrough in the framework of Task 3.4, and the respective pro-

totype dataset was also used for the development of an automated gas bubble detection algorithm for WCI da-

ta.

However, continuous observation of the acoustic signals in the water column as well as compilation of existing

observations have so far led to the picture that gas ebullition is of minor importance in the Baltic Sea (except for

the Kattegat), as is the occurrence of pockmarks hinting to potential gas ebullition (with only one structure

found in the Mecklenburg Bay, one in the Arkona, Basin, known groundwater structures in the Eckernförder Bay,

and the exception of the Pockmark area in the Russian sector). This is in accordance with the general observa-

tion of a strong gradient in methane concentration across the pycnocline, which would be “blurred” by vertical

ascent of bubbles. Based on the work performed within Baltic Gas, it can be argued that the low pressure shal-

low gas accumulations do not drive methane ebullition, that the few indications of gas seepage point to episodic

emission and a strong seasonal bias (i.e. bottom water temperature), and are expected to strongly react to wind-

driven water level changes. These considerations are compiled in Deliverable report 3.3.

WP 4: Biogeochemistry (reported by Timothy Ferdelman, Max Planck Institute for Marine Microbiology, Germany)

Task 4.1: Methane distribution and geochemical in situ gradients 4.1.1: Sulfur biogeochemistry 4.1.2: Methane biogeochemistry

Task 4.2: Gas emission across sediment-water and sea-air interface 4.2.1: Methane flux and ebullition measurements 4.2.2: Hydrogen sulphide flux

44

4.2.3: Water column methane and ferry box surface methane measurements

Task 4.3: Methane and key biogeochemical processes 4.3.1: Quantify production and breakdown of methane 4.3.2: Analyze controls on relevant key geochemical processes 4.3.3. CH4 and H2S oxidation coupled to water column oxygen consumption

Task 4.4: Holocene evolution of the Baltic Sea ecosystem


4.1. Methane distributions and breakdown

4.2. Methane emission through sediment-water and sea-air interfaces

4.3. Holocene evolution of the Baltic Sea ecosystem

4.4. Submitted MS on: Sulphur and methane biogeochemistry

Task 4.1: Methane distribution and geochemical in situ gradients

The first two years of the project were, to a large extent, dedicated to obtaining high quality, high resolution

down-core geochemical data related to methane and sulfur biogeochemistry. The following regions were identi-

fied as important sampling and study regions:

• Gulf of Bothnia (i.e. Bothnian Bay and Sea)

• Vyborg/Gulf of Finland

• Himmerfjärden

• Gotland Deep

• Stolpe Fore Delta, Mid-Baltic

• Kaliningrad Sector

• Gdansk Basin

• Bornholm Basin

• Arkona Basin

• Mecklenburg Bay

• Aarhus Bay

A number of sampling campaigns were undertaken to evaluate the methane and sulfur biogeochemistry in Baltic

Sea sediments:

• An expedition to Himmerfjärden (Askö Marine Lab, Sweeden) where scientists and students from three

BALTIC GAS Institutes participated in a field campaign to obtain cores from the Himmelfjärden, an an-

thropogenically impacted fjord in the north-central basin of the Baltic Sea. The principal goals were to

obtain baseline porewater, gas, and solid phase sediment data for the Baltic Gas project, as well as to

obtain samples for experimentation and flux measurements. In addition, this expedition provided the in-

itial training for 2 BALTIC GAS doctoral students in pore water sampling.

• The aforementioned doctoral students joined the R/V Aranda Expediton with BONUS HYPER scientists

on a coring expedition throughout the entire length of the Baltic Sea.

• A BALTIC GAS biogeochemist was invited to participate on the F/S Merian cruise M12-4a project with

partners from 4 different BONUS projects participated: INFLOW, BALTIC-C, AMBER, and BALTIC GAS.

Stations for BALTIC GAS activities targeted the Gotland Deep, Aland Sea, Bothnian Bay and Bothnian

Bight, as there have been no published data on the distribution, depth, and abundance of methane in

sediments from the oligotrophic, low-salinity northern Baltic Sea.

• Employing a unique, converted ferry boat, the Susanne A, as a sampling platform, a high resolution, bio-

geochemical sampling transect was completed along a gas-rich seismic line in Aarhus Bay.

45

• The Bay of Gdansk was targeted for high resolution sediment porewater methane and sulfate profiling

and experimentation during the BALTIC GAS R/V Oceana expedition in November 2009 by scientists

from three BALTIC GAS institutes.

• During the course of a three week expedition in December on the R/V Poseidon, BALTIC GAS scientists

from 4 institutes collected high resolution pore water samples for methane and chemistry analyses

along seismic transects in Mecklenburger Bay, Arkona Basin, Bornholm Basin, and the Stolpe Foredelta.

• A return expedition to Himmerfjärden (Askö Marine Lab, Sweeden) in June where scientists and stu-

dents participated in a field campaign to obtain cores from the Himmelfjärden, an anthropogenic im-

pacted fjord in the north-central basin of the Baltic Sea.

• Extensive sampling of Aarhus Bay was performed during the Arhus Bay Cruise (ABC2010) using the Su-

sanne A in April. Long gravity cores were taken for further geochemical work-up

• The sampling highlight of the year was the major two-leg expedition onboard the German research ves-

sel R/V Maria S. Merian in over 3.5 weeks in August of 2010. Surface multi-core and deep gravity cores

were obtained from the southern, central and into the northern Baltic reaches. Extensive gas, pore wa-

ter, solid phase sampling and radiotracer experimentation on the retrieved cores was performed.

The Baltic Gas project focused extensively on acquiring a large data set of sulfate and methane distributions in

Baltic Sea sediments. The dominant experimental/field approach to the problem was to study the connection

between the seismic signals observed in the sediment (i.e. seismic picture) and ‘in situ’ concentration profiles of

methane, sulfate and other pore water constituents. Thus, targeted sediment sampling was performed based on

seismic signals along transects reaching from sediments with deep or no ‘methane-reflection’ of the seismic

signal (i.e. non-gaseous sediment) to sediments with methane saturation (and thus a sharp reflection, i.e. gase-

ous sediment) in the (surface) sediments. In addition to sulfate and methane, corresponding chemical species

such as δ13

CH4, density/porosity, CN-content, and pore water (i.e. SO42-

, Cl-, H2S, Fe

2+, PO4

3-, DIC, metals, and

nutrients), and 210

Pb were often also measured.

Generally, analyses of the pore water data suggest that in the diffusive systems of the southern Baltic the thick-

ness (accumulation rate of organic rich sediment) of the Holocene mud layer is a controlling variable for the flux

of methane. Deeper layers are not a source of methane. High resolution porewater sampling and analyses from

both the R/V Poseidon 2009 expedition and the R/V MS Merian expedition to Bornholm Basin reveal a deep flux

of methane into the underlying clay sediments. In the northern, low salinity reaches of the Baltic, the methane-

sulfate interface is within a few tens of centimetres of the sediment-water interface. Finally, the first map of

sedimentary dissolve methane fluxes from deep sediments to the surface sediment has been produced based on

data collected from Baltic Gas and data mining .

Task 4.2: Gas emission across sediment-water and sea-air interface

4.2.1.1 Methane flux and ebullition measurements

For the near-shore coastal flux quantification, two field areas were selected: The southern Stockholm archipela-

go with the case study area Himmerfjärden and the archipelago off Västervik in southern Sweden. Floating, La-

grangian, methane-gas flux chambers were deployed in the littoral regions of Swedish Baltic waters. In 2009, an

assemblage of 38 chambers was distributed for 24 hour-flux measurements from very-shallow 0.5 m water

depth to 8 m water depth.

In 2010, additional 15 chambers were deployed near Hornsudde, Västervik to compare inshore fluxes within the

eutrophic southern Stockholm archipelago with fluxes in this less populated coastal area to the south. Finally, in

46

2011, 15 more stations were selected along the eutrophication gradient of the Himmerfjärden and in neighbour-

ing bights including selected stations surrounding the SYVAB sewage treatment plant in order to assess the ef-

fect of treated sewage discharge for methane concentrations and fluxes to the atmosphere and to determine

onshore-offshore trends in methane fluxes.

These measurements were conducted in the early summer and fall. The combined data suggest that the littoral

regions of the Baltic Sea have been underrepresented in estimates of fluxes of methane gas from the water col-

umn to the atmosphere. Very shallow water fluxes ranged from 5 to 553 µmol m-2

d-1

in the very shallow water

environments. In coastal waters between 10 m and 75 m depth, fluxes varied between 11 and 168 µmol m-2

d-1

.

There was no significant relationship between methane and fluxes and water depth. The highest fluxes, howev-

er, were measured in very shallow water (0.5 m depth), where it is likely that bubble emission significantly con-

tributed to the total flux. A comparison with fluxes calculated from surface methane concentrations determined

with ICOS-water equilibration system (4.2.3) shows that the inshore fluxes exceed the offshore fluxes by more

than an order of magnitude.

4.2.1.2 Benthic fluxes

A large data set of benthic flux measurements was assembled from the various research cruises in 2009 and

2010. The temporal variability in benthic fluxes was assessed in the Himmerfjärden area, where spring and late

summer data were acquired in June and September 2010 and compared to early spring data acquired at the

same stations in May 2009. Benthic fluxes and fluxes to the sediment surface were calculated from porewater

concentrations obtained directly after collecting sediment cores in order to avoid gas loss. The measurements

and calculations indicated a high variability in benthic fluxes ranging from near zero to 3625 µmol m-2

d-1

. The

highest fluxes were determined in the inshore areas and suggest an important ebullition component.

4.2.2: Hydrogen sulphide fluxes

Porewater concentrations of hydrogen sulphide fluxes were determined on RV Aranda, Merian, Poseidon, and

Limanda cruises. These data are fitted in reactive transport pore water fitting models to calculate fluxes of hy-

drogen sulphide to the sediment surface. Of particular relevance was to establish potential correlations between

methane and hydrogen sulphide fluxes. At present, only part of the available pore water sulphide data were

analyzed to calculate hydrogen sulphide fluxes. In these instances, the presence of Fe-oxyhydroxide near the

sediment surface effectively eliminated the hydrogen sulphide flux to the water column decoupling transport of

hydrogen sulphide and methane. Further analysis of the remaining pore water data will continue.

4.2.3: Water column methane and ferry box surface methane measurements

To obtain a synoptic view of the temporal and spatial in surface methane concentrations sea-air fluxes of me-

thane, a CH4-CO2-H2O analyzer was installed in November 2009 on the cargo ship M/S Finnmaid (Finnlines),

which commutes regularly between Travemünde (Germany) and Helsinki (Finland). The analytical setup consists

of a methane carbon dioxide-analyzer based on off-axis integrated cavity output spectroscopy (ICOS) analyzer

coupled to an established water-air equilibrator setup. With this system, methane concentration time series in

the surface water were obtained in two- to three-day intervals for the western and central Baltic. In addition

water column methane distributions were determined on the December 2009 RV Poseidon expedition. These

provided a detailed picture of the early winter depth distribution of methane, which support the synoptic distri-

butions of methane obtained from the ferry box IR spectrosopy measurements. On the RV Maria S. Merian ex-

pedition M16-1, the methane distribution in the water column was assessed, revealing amongst other findings a

drastic increase in bottom water methane concentration between the post bloom summer situation and the

47

situation in the winter of 2009, in connection to the occurrence of a benthic nepheloid layer. Very low post-

bloom surface pCO2 values and distinct patterns of surface methane concentrations obtained from the surface

survey using ICOS pointed to local sources.

A 2nd system was built for shipboard work on research vessels and was successfully used to monitor the gas

concentrations along the ship track during RV Maria S. Merian expedition 16-1b in August 2010. The highest

methane fluxes were found during the autumn and winter period. The annual interaction of stratification and

mixed layer depth was found to be a key parameter for methane fluxes in deeper regions like Gulf of Finland or

Bornholm Basis. Methane fluxes from shallow regions like the Mecklenburger Bight are controlled by sedimen-

tary production and consumption of methane, wind events and the temperature induced change of the solubili-

ty of methane in the surface water.

Task 4.3: Methane and key biogeochemical processes

Two years of the project were dedicated to the successful completion of several major cruises to the Baltic Sea,

and to gather all known geochemical data from the Baltic. The purpose of these cruises was to determine the

distribution of shallow gas in sediments, quantify the production and breakdown of methane, and analyze con-

trols on relevant key geochemical processes. A number of scientific results were gained during these two years:

• During the 2009 Poseiden cruise, long (10 meter) sediment cores were collected from Bornholm Basin

and measured for methane concentrations, along with many other geochemical parameters. Methane

concentrations first showed the typical increase with sediment depth but then decreased again with

depth, indicating downward diffusion (sink) of methane into Baltic Ice Lake sediments. Although, the

sink for the methane in these iron- and manganese-oxide rich sediments is not clear. Radiotracer exper-

iments (started on R/V MS Merian expedition) to elucidate mechanisms of the methane oxidation in

these deep sediments are underway.

• Using powerful acoustical techniques, the distribution of shallow gas in Baltic sediments can be deter-

mined. These techniques are mainly shipboard operations and quicker than traditional sediment coring.

On the 2010 Merian cruise, we used parasound techniques to find shallow gas deposits in the Arkona

Basin. The acoustic signals of gas were groundtruthed with sediment coring to confirm these results.

Such techniques can be used in the future to search for shallow gas.

• To analyze controls on methane accumulation on sediments, we used a two-tiered approach. First,

seismic lines were gathered, and then, sediment coring stations chosen based on these lines. For exam-

ple, a transect was carried out in the northern Gotland Basin. Along this line, the seismic reflections

showed areas with gas accumulations, thick layers of Holocene sediments, and thin layers of such sedi-

ments. Results showed that methane concentrations were high where acoustic anomalies suggested

shallow gas, and low where no gas was pictured.

• In the Bothnian Bay, a seafloor gas flare was imaged in the water column. Upon coring the sediments

below this flare, sediment pore-water methane concentrations were quite high, reaching near satura-

tion at in situ temperatures and pressures. Although this does not prove the existence of the flare, it

supports that a flare was possibly sourced in the sediments.

• One key goal of BALTIC GAS was to analyze a number of key controls on the geochemical distribution of

methane. To do this, we compared the flux of methane out of sediments to bottom water temperature,

bottom water salinity, water depth, carbon content and organic carbon quality. No correlations were

found with physical processes, such as salinity, temperature, or water depth. However, the collective

48

data over the entire Baltic as well as a very detailed study along a transect of increasing mud thickness

in Aarhus Bay, revealed that the quality as well as the amount of organic matter buried in the sediment

play a crucial role in gas formation and its accumulation

• Experiments combined with stable isotope measurements from samples taken in Aarhus Bay suggest

that the sulfur cycle may be active in the methane oxidation process below the sulfate-methane transi-

tion zone. Solid phase analyses combined with sulfur isotope analyses suggest that a major sink for re-

duced sulfur in the Baltic Sea appears to be organically-bound sulfur

• Methanogenesis experiments in the highly organic rich sediments of Himmerfjärden demonstrate that

the highest rates of methane production (principally through bicarbonate reduction) are occurring just

below the sulfate-methane transition zone. In Himmerfjärden, where sulfate penetration depths are

very shallow this leads to a steep gradient of methane towards the surface sediments .

• Key controls on the methane flux out of sediments were also analyzed on a local level at Himmerfjärden,

Sweden. The estuary has very high sedimentation and organic carbon accumulation rates compared to

open Baltic sediment (0.65 cm/a in the outer compared to 0.91 cm/a in the inner part of the estuary.

These rates correlate well with the organic carbon accumulation rates and the calculated diffusive fluxes

of methane to the sediment surface indicating that the amount of deposited organic matter is a key

driver for methane fluxes.

• Sedimentation rates were calculated from sediment cores collected during the Merian cruise August

2010. Rates were 0.3, 0.2, and 0.1 cm/yr for sites in the Gotland Basin, the Bothnian Sea, and Bothnian

Bay, respectively. Such data will be input into a larger database that was published in Geo-Marine Let-

ters, 2010 by Leipe and colleagues, and will be used in the GIS work of the Baltic Gas project.

• Carbon stable isotopes of dissolved methane from the 2010 Merian and 2009 Poseidon cruises were

measured. A unique signature of methane production was found in the very surface layers of the cores,

a sediment depth not typically known to produce methane due to the high concentrations of sulfate.

Task 4.4: Holocene evolution of the Baltic Sea ecosystem

The overall goal of the task was describe the Holocene evolution of the Baltic Sea ecosystem. To achieve this

goal, we participated in a number of different sampling campaigns throughout the 3 years of the BALTIC GAS

project utilizing important infrastructures from different countries around the Baltic Sea. We collected 33 long

sediment gravity cores with accompanying surface cores. Briefly, cores were split into two sections, described

for sediment characteristics and photographed. A number of analyses were preformed, especially different

methodologies for dating sediments using 14C and lead concentrations/stable istopes, and mineral magnetic

measurements.

A one-day workshop was held in Warnemünde (September 2009) to introduce the scientists in the BALTIC GAS

project to problems associated with evaluating Holocene evolution of the Baltic Sea. Alternate dating methods,

for instance the use of lead isotopes (lead pollution history) have led to a refined age-model for reconstructing

Baltic Sea sedimentation and basin development.

A precise determination of reservoir ages is one of the most problematic parts of establishing an accurate chro-

nology of sedimentation in the Baltic Sea. Reservoir ages in the Baltic Sea vary due both to changes in salinity,

e.g. due to salt water input from the Kattegat, and due to older carbon entering the Baltic Sea from freshwater

sources. Recent work has established that reservoir ages have decrease through the last 8,000 years of Baltic Sea

history (Lougheed et al., Submitted). In our project we attempted to obtain adequate numbers of foraminifera,

49

although we were unsuccessful. We, therefore, are using reservoir dates determined by (Lougheed et al., Sub-

mitted). In addition, we successfully applied a methodology new to the Baltic Sea regarding the use of lead con-

centration profiles and isotopes (Zillén et al., Accepted) to better determine time markers for the last 1000 years

of Baltic Sea history.

The mineral magnetic measurements provided a unique signature for laminations. When the Baltic Sea is hypox-

ic with laminations present, the magnetic susceptibility of the sediments greatly increased. We have investigated

the ferromagnetic properties of these materials including magnetic separation of mineral particles from bulk

sediments. The preliminary conclusion is that the material is likely magnetite magnetosomes made by magnoto-

tactic bateria.

Further, we have contributed to a paper on the topic of the evolution of the Baltic Sea ecosystem through time

(Andrén et al., 2011) and our sediments studies have improved our understanding of changes in the Baltic Sea

ecosystem through time.

WP 5: Modelling and data integration (reported by Pierre Regnier, Department of Earth Sciences, Utrecht University, The Netherlands)

Task 5.1: Modelling methane and sulfur dynamics 5.1.1: transport-reaction models 5.1.2: Predictive models (i.e. climate change scenarios)

Task 5.2: GIS-modelling

Task 5.3: Integrating gas, acoustics and biogeochemistry


5.1. Transport/ reaction models reg. methane and sulphur dynamics

5.2. Predictive model and climate change scenarios

5.3 Submitted MS on: Integration gas, acoustics and biogeochemistry

Task 5.1: Modelling methane and sulphur dynamics

5.1.1: Reaction-transport models

We have developed a detailed model for the coupling of the benthic methane and sulphur cycles. This reactive-

transport model (RTM) includes methane gas formation, migration and dissolution in marine sediments

(Mogollon et al., 2011)5. It has been validated against field data (organic carbon content and sedimentation

rates, aqueous ammonium, dissolved inorganic carbon, sulphate and methane profiles, sulphate reduction rates,

depth of free gas) collected by the partners of the project in several gassy areas of the Baltic Sea. The RTM oper-

ates both under steady-state and transient conditions (seasonal and secular variations).

The model has been applied to unravel the methane cycle in Arkona Basin (south-western Baltic Sea). The model

was used to quantify the changes in production and consumption of aqueous and gaseous methane over the last

8000 yrs as a result of the marine transgression in the Baltic Sea (Mogollon et al., 2011)6. The relationships be-

5 Mogollon, J.M., A. Dale, I. L’Heureux, and P. Regnier, P. (2011) Seasonal controls on methane gas and anaerobic oxidation of me-

thane in shallow marine sediments. Journal of Geophysical Research. 116, G03031, doi:10.1029/2010JG001592. 6 Mogollon, J.M., Dale, A., Fossing H. and Regnier, P. (2011b) Timescales for the development of methanogenesis and free gas layers

in recently-deposited sediments of Arkona Basin (Baltic Sea).Biogeosciences Discuss., 8, 7623–7669.

50

tween the thickness of organic rich-muds, methanogenesis and methane gas production has been investigated.

A similar modelling study has been conducted in the gassy sediments of Aarhus Bay (together with dr. Dale, IFM-

GEOMAR, DE) where high resolution profiles of concentrations and rates have recently been measured by Baltic

Gas partners. Here, the focus is on how the flux and reactivity of organic matter controls the formation and

depth of gassy layers, as determined by high resolution seismic images. Numerical simulations show that the

main trigger for gas formation is the bulk sediment accumulation rate associated with increasing mud thickness.

High accumulation rates dilute the organic material deposited on the sea floor with inorganic material, yet lead

to a more rapid burial of reactive organic matter fractions to the methanic zone and higher rates of methano-

genesis as well as gas production. Modeling of stable carbon isotope distributions provides further constrains on

the coupled methane and sulfur cycles and reveals that methane gas advection towards the sediment-interface

is very likely. Nevertheless, all our model results show that anaerobic oxidation of methane (AOM) acts as a very

efficient subsurface barrier against aqueous and gaseous methane escape into the overlying water column. The

work carried out in the framework of Baltic-gas has been integrated in a broader framework and summarized in

a review paper (Regnier et al., 2011)7

The modelling tools have also been used to establish basin-scale budgets of methane production and consump-

tion in the Baltic Sea. First, a link between the thickness of the organic rich mud and the amount of aqueous and

gaseous methane being produced was established. Next, using the mud thickness (and sedimentation rate) as a

master variable for the simulations, spatial extrapolation was conducted and a basin-scale budget was estab-

lished. This approach was corroborated for the Arkona Basin, using the extensive seismic surveys carried out in

this area. Based on the model results, we have also developed a prognostic indicator for methane fluxes based

on the depth of methane gas and the methane solubility concentration. This indicator has been used in combi-

nation with GIS tools to establish first-order regional estimates of methane production in the Belt seas and Ore-

sund (Denmark).

5.1.2: Predictive models (including climate change scenarios)

The RTM developed for Arhus Bay sediments has been extended to simulate the effects of eutrophication and

climate at the centennial timescale. The model can account for changes in bottom-water sulphate due to fresh-

ening of the Baltic, changes in organic matter flux triggered by variations in productivity and variations in bot-

tom-water temperatures. The model was applied at different locations in the Baltic Sea to forecast the increase

in methane gas inventories triggered by climate change in the Baltic Sea region. Full transient simulations were

performed for the period 2010-2110, using the boundary forcing’s extracted from a 3D ecosystem model of the

Baltic Sea (Neumann 2010)8. The latter was constrained using a regional data set for greenhouse gas emission

(scenario A1B), which allows to predict changes in temperature, freshwater inflows, sea-ice cover and productiv-

ity over the entire Baltic Sea with a horizontal resolution of 18 km.

Two shallow benthic areas were considered: a transect in Arhus Bay, where temperature rise could be significant

(circa 1.8 degrees for the period 2010-2110) and the Bothnian Bay, were the combined effects of freshening and

warming (circa – 1.5 PSU and + 2.2 degrees) could trigger a significant increase in gaseous methane production.

The site selection will be complemented in the near future by an investigation of a sediment core from the

Bornholm Basin, where methane gas formation occurs at significantly greater water depth. Results reveal that

7 Regnier P., Arndt, S., Dale, A.W., LaRowe, D.E., Mogollon, J. and Van Cappellen, P. (2011). Quantitative analysis of anaerobic oxi-

dation of methane (AOM) in marine sediments: A modeling perspective. Earth Science Reviews. 106, 105-130. 8 T. Neumann, Climate-change effects on the Baltic Sea ecosystem: A model study, Journal of Marine Systems 81 (2010) 213–224

51

the gas inventory in the sediments and the areal coverage of the gassy zones could increase significantly (depth

integrated gas content higher by up to a factor of 5 in some areas). The position of the gas front could also be

significantly shallower than today. Because of the large uncertainties in gas ascent and dissolution rates, includ-

ing their response to changes in environmental conditions, the capacity of the sedimentary methane gas to es-

cape to the atmosphere remains nevertheless uncertain.

Task 5.2: GIS- Modelling

The compilation of data about the occurrence of free gas in surface sediments, chemical composition of pore

waters, bottom water chemistry, sediment distribution, accumulation rates of particulate organic matter (POC)

as well as observations of pockmarks derived in WP 2 (Data mining and GIS-mapping), allows the spatial analysis

of factors favorable for the formation of methane in sediments of the Baltic Sea.

Complementary to process oriented modeling by numerical Reaction-Transport-Modeling we applied a statistical

approach using different GIS techniques supporting spatial modeling. For this purpose former mentioned data

sets were converted to raster data using a similar grid size and map projection. For spatial budgets and analysis

we applied a Lambert azimuthal equal-area projection. By GIS techniques like overlay, we selected for areas

where free gas is observed the values for POC accumulation rates, water depth, seafloor morphology etc. More

than 10 different parameters were considered by the GIS modeling of the spatial distribution of the occurrence

of free gas.

For each parameter the data selected from free gas areas were compared with data in the surrounding (e.g. sub-

basins of the Baltic proper) where no free gas appears. Based on this approach and applying statistical means we

derived a factorization of parameters which are likely to contribute to the formation of free gas. The factoriza-

tion, which was iteratively improved, was used to compute predictive maps about the spatial distribution and

the total area of free gas in sediments of the Baltic Sea.

The derived maps were cross validated by extracting data from the full data set and computing a new estimate

based on reduced set as well as by consideration of seismic lines. The later allows identifying false positive cases,

where free gas is predicted but not detected by seismic investigations. As a step towards an even improved GIS

modeling, the reliability of the spatial distribution of parameters like mass accumulation rates will be considered

to identify regions with a higher/lower statistical confidence of prediction.

Task 5.3: Integrating gas, acoustics and biogeochemistry

Among the main goals of BALTIC GAS were the quantification and mapping of methane fluxes in the Baltic sea-

bed. This was previously done by taking several-meter deep sediment cores in which the depth distribution of

methane was analyzed. The capacity for such coring during research cruises was very limited, however, consider-

ing the number of cores needed to make regional extrapolations or even draw maps of methane fluxes. Since

areas of high methane accumulation and turnover are particularly important as potential sources of methane

ebullition such hot-spots were among the primary targets for the project.

In many areas of the Baltic Sea methane production leads to free gas formation in the subsurface seabed. The

gas bubbles are highly visible in seismo-acoustic transects using appropriate instruments and the top of the bub-

ble zone can be easily recorded and mapped. In BALTIC GAS we used the distribution and depth of the bubbles

as a proxy for high methane fluxes. Fig. 5.1 shows the rationale for this approach by which the methane flux was

calculated according to the following equation:

52

Flux (CH4) = -(Φ/∆Ztotal) (Ds(SO42-

) [SO42-

]sw + Ds(CH4) [CH4]bubble) Eq. 5.1

where the symbols (and their source) are:

∆Ztotal = ∆ZSO4 + ∆ZCH4 = depth of onset of bubbles (from acoustics)

[SO42-

]sw = sulfate concentration (from seawater salinity)

[CH4]bubble = methane saturation concentration at onset of bubbles (from water depth)

Ds(SO42-

) = diffusion coefficient of sulphate (from literature)

Ds(CH4) = diffusion coefficient of methane (from literature)

Φ = porosity (from sedimentology)

As seen from Eq. 5.1, the depth of onset of

bubbles can be used for the calculation of

methane fluxes, provided that a number of

parameters are known. Those parameters

are, however, all easy to measure and map,

e.g. salinity, water depth plus bubble depth

below the sediment surface, diffusion coef-

ficients of sulfate and methane at the am-

bient bottom water temperature, and sed-

iment porosity.

During joint cruises of geophysicists and

geochemists the strategy was to use initial

seismo-acoustic mapping to guide the sub-

sequent targeted coring of sediment.

Thereby, it was possible to obtain multiple

combined data sets of methane profiles

and gas depth to calibrate the algorithm

and to test it in different regions, water

depths and geological settings in the Baltic

Sea. The approach proved highly successful

and is the basis for the hot-spot maps of

methane fluxes that are now available for a

number of areas in the Baltic Sea. It is also

the basis for models that explain the rela-

tionship between methane gas accumulation and the thickness of organic-rich Holocene mud. Finally, it is used

in the forecasting models that predict the future development and areal extent of gassy sediments in the Baltic

Sea.

Fig. 5.1. Conceptual model used for the calculation of methane

fluxes based on the depth of gas bubbles. In reality, the model used

was a more complex and realistic reactive-transport model, but this

figure may serve as a simplified illustration of the principles.

53

4. BALTIC GAS Science team

Group photo from the final BALTIC GAS Workshop, held in Aarhus, Denmark, November 1-3, 2011

Center for Geomicrobiology, Department of Biociences, Aarhus University, Denmark

Bo Barker Jørgensen ([email protected]) coordinator, WP1-leader

Britta Gribsholt

Sabine Flury

Hans Røy

Irene Harder Tarpgaard

Laura Lapham

Camilla Nissen Toftdal

Department of Biociences, Aarhus University, Denmark9

Henrik Fossing ([email protected]) Principal scientist, assisting coordinator and WP1-leader

Geological Survey of Denmark and Greenland, Copenhagen, Denmark

Jørn Bo Jensen ([email protected]) Principal scientist, WP2-leader

Zyad Al-Hamdani

Lars Georg Rödel

Department of Earth Sciences, University of Bremen, Germany

Volkhard Spiess ([email protected]) Principal Scientist

Hanno Keil

Noemi Fekete

Tilmann Schwenk

Zsuzsanna Toth

Marius Raab

9 Formerly named National Environmental Research Institute, University of Aarhus, Denmark

54

Max Planck Institute for Marine Microbiology, Bremen, Germany

Timothy Ferdelman ([email protected]) Principal scientist, WP4-leader

Michael Formolo

Thang Manh Nguyen

Natascha Riedinger

Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany

Michael Schlüter ([email protected]) Principal scientist

Ellen Damm

Sabine Kasten

Torben Gentz

Michiel Rutgers van der Loeff

Kerstin Jerosch

Baltic Sea Research Institute Warnemünde, Germany

Gregor Rehder ([email protected]) Principal scientist, WP3-leader

Rudolf Endler

Thomas Leipe

Wanda Gülzow

Jens Schneider v Deimling

Oliver Schmale

Sascha Plewe

Institute of Oceanology, Polish Academy of Science, Gdansk, Poland

Klusek Zygmunt ([email protected]) Principal scientist

Piotr Majewski

Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia

Nikolay Pimenov ([email protected]) Principal scientist

Timur Kanapatsky

Vadim Sivkov10

Marina Ulyanova10

Dmitry Dorokhov10

Department of Geological Sciences11

, Stockholm University, Sweden

Volker Brüchert ([email protected]) Principal scientist

David Bastviken12

Patrick Crill

Livija Ginters

10 Russian Academy of Sciences, Shirshov Institute of Oceanology, Atlantic Branch, Kaliningrad, Russia 11 formerly named Department of Geology and Geochemistry 12 Department Water and Environmental Studies, Lindköping University, Sweden

55

Department of Geology, Lund University, Sweden

Daniel Conley ([email protected]) Principal scientist

Maja Reinholdsson

Svante Björck

Department of Earth Sciences, Utrecht University, The Netherlands

Regnier Pierre13

([email protected]) Principal scientist, WP5-leader

Philippe van Cappellen14

José Mogollon15

Andy Dale16

5. Educational activities

A total of 7 PhD and 2 Master students received part of their educational training during BALTIC GAS of which

two students graduated during 2011 and the rest will give in their thesis/ dissertation during the next two years.

Name Institution Graduation

Ph.D students

Thang Manh Nguyen

Max Planck Institute for Marine Microbiology

Bremen, Germany

Jan 2009 – Dec 2011 Nov 2012

Maja Reinholdsson Department of Geology

Lund University, Sweden

Feb 2009 – Dec 2011 Sep 2013

Piotr Majewski Institute of Oceanology

Polish Academy of Science Gdansk, Poland

Jan 2009 – Dec 2011 2013

Wanda Gülzow Baltic Sea Research Institute Warnemünde

Germany

Jan 2009 – Dec 2011 Jun 2012

José Mogollón Department of Earth Sciences

Utrecht University, The Netherlands

Mar 2010 – Feb 2011 May 2011

Zsuzsanna Toth Department of Earth Sciences

University of Bremen, Germany

Sep 2009 – Dec 2011 Dec 2012

Torben Gentz Alfred Wegener Institute for Polar and Ma-

rine Research, Bremerhaven, Germany

Jul 2009 – Dec 2011 Sep 2012

Master students

Stine Thomas Baltic Sea Research Institute Warnemünde

Germany

Oct 2010 – Jun 2011 Jun 2011

Livija Ginters Department of Geological Sciences Stock-

holm University, Sweden

May 2010– Oct 2010 Feb 2012

BALTIC GAS educational activities comprised students’ participation in workshops, research cruises, meetings

and conferences and at a training course: Seismo-acoustic Imaging of Sedimentary and Gas-related Features in

the Baltic Sea, the latter funded by The EEIG Steering Committee.

Now at

13Dept. Earth & Environmental Sciences Université Libre de Bruxelles, Belgium

14Canada Excellence Research Chair in Ecohydrology, University of Waterloo, Ontario, Canada

15Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany

16 Dept. Marine Biogeochemistry, IMF-Geomar, Kiel, Germany

56

BALTIC GAS workshops (Table 1; 1. Executive Summary) had all Ph.D. and Master students participating with

presentation of their research projects, engaged discussions, and evaluations of BALTIC GAS results in general.

At BALTIC GAS research cruises PhD-students were trained how to handle heavy sampling gear for water and

sediment sampling, seismo-acoustic imaging of the sea floor, onboard good laboratory praxis, recording a cruise

logbook, and participation at onboard scientists meetings comprising research presentations, scientific discus-

sions, general cruise logistics etc. Cruises with PhD-participation comprised (see also Table Y2; 1. Executive

Summary)

• 2 Ph.D.: RV Oceania, Feb. 20 – 27, 2009

• 2 Ph.D.: RV Limanda, May 12 – 17, 2009

• 2 Ph.D.: RV Aranda, Jun. 4 – 17, 2009

• 1 Ph.D.: RV Susanne A, Oct. 6, 2009

• 4 Ph.D.: RV Oceania, Nov. 5 – 16, 2009

• 1 Ph.D.: RV Poseidon, Nov. 27 – Dec 17, 2009

• 2 Ph.D.: RV Susanne A, May 4, 2010

• 9 Ph.D.: RV Merian, Jul. 31 – Aug. 21, 2010

• 2 Ph.D.: RV Limanda, Jun. 10 – 14, 2010

• 2 Ph.D.: RV Limanda, Jun. 10-16, 2011

Additionally a cruise planning workshop reg. RV Maria S. Merian cruise MSM 16/1 was offered at Stockholm

University and Askö Field Station Laboratory (Sweden), June 6 – 7, 2010 where a total of 7 PhD-students were

introduced to and actively participated in planning of this major research cruise.

Meetings and conferences (see 7. Meetings and conferences) were important fora for Ph.D.-students to present

their research, to network and improve their scientific career. Thus, in BALTIC GAS the principal scientists gave

highest priorities to Ph.D.-students to participate in such events with oral and/or poster presentations:

• 1 Ph.D.: Association of Hungarian Geophysicists, Mátrafüred, Hungary, 26-27 March 2010, Hungary, 26-

27 March 2010

• 1 Ph.D.: EGU General Assembly, Vienna, May 2-7 2010

• 1 Ph.D.: 10th

International Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia, 6-12

September 2010

• 1 Ph.D.: AGU, San Francisco, USA. December 13-17 2010

• 1 Ph.D.: EGU General Assembly, Vienna, 3-9 April 2011

• 1 Ph.D.: Bremen PhD days in Marine Sciences 2011, University of Bremen, Bremen, Germany, 13-14

April 2011

• 5 Ph.D.: 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, August 22-26 2011

• 1 Ph.D.: 2nd Young Scientist Excellence Cluster Conference on Marine and Climate Research, Bremen,

Germany, 4-5 October 2011

The training course in Seismo-acoustic Imaging of Sedimentary and Gas-related Features in the Baltic Sea was

organized by University of Bremen, Germany, and University of Szczecin, Poland, took place in the Malkocin

57

Conference Center of the University of Szczecin (Poland) and on board the Polish M/V Nawigator XXI during 15-

27 July, 2010.

Altogether 20 students participated of which 6 students came from the University of Szczecin (Poland) and 14

students were active in the BONUS-projects: Baltic Gas, Inflow and Hyper comprising the „BONUS-institutions:

Institute of Oceanology of the Polish Academy of Sciences (Poland), P.P. Shirshov Institute of Oceanology of the

Russian Academy of Sciences (Kaliningrad, Russia), and University of Bremen (Germany).

During the three-day preparatory course the marine geology of the Baltic Sea was presented by an invited lec-

ture (Jan Harff, IOW/US), and the relevant instruments and survey methods of acoustic surface and sub-surface

imagery were introduced to both geophysicist and non-geophysicist participants. Discussions about cruise plan-

ning strategies aimed to acquaint participants with considerations leading to flexibility and successful decisions

in scientific cruise management. The seagoing expedition on RV Nawigator XXI was carried out in the Polish wa-

ters of the Baltic Sea. Seis-mic and side scan sonar data were collected in the Pomeranian Bay, eastern Bornholm

Deep and offshore Wladyslawowo during the cruise. During these days, participants gathered experience in

equipment handling, data acquisition, processing of seismo-acoustic data, and using preliminary interpretations

to aid cruise planning. The expedition was followed by a two-day post-cruise evaluation workshop. Results were

evaluated, put in scientific context, and collected in a preliminary cruise report. Cruise participants presented

selected topics in short lectures, highlighting different aspects of new data from the perspective of regional ge-

ology. Main scientific results include indications of shallow gas found south of Bornholm, and the mapping of a

basement fault zone in the eastern study area.

The course convinced us that a mixture of theory and practice taught in groups produces fruitful discussions

between young scientists and enthusiasm as well as knowledge about the selected topic.

6. Stakeholder events and other related activities

6.1 Stakeholder and scientific committees

BALTIC GAS scientists 31 times during the program period served as members or observers in stakeholder and

scientific committees and once in consultations carried out by the European Commission (see Statistics for the

performance assessment of the Programme).

2009 - Stakeholder and scientific committees

1. Conley, Daniel (Lund University) SCANBALT Forum, Kalmar, Sweden, 9 September 2009

2. Ferdelman, Timothy (Max Planck Institute, Bremen) 13th Meeting of the IODP Science Steering and

Evaluation Panel. Melbourne, Australia, 16-18 November 2009

3. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Advisory Board, Alfred

Wegener Institute for Marine and Polar Research, Bremerhaven, Germany, 2-day Meeting in Bremerha-

ven 2009

4. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Advisory Board, Faculty

of Biology, University of Vienna, Austria, 2-day Meeting in Vienna 2009

58

5. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Planning Committee for

IODP Drilling Proposal in Baltic Sea, 1-day Magellan Workshop on IODP Drilling Project 2009

6. Pimenov, Nikolay (Winogradsky Institute of Microbiology, Moskow) Steering committee for the Interna-

tional Workshop “Geological and bio(geo)chemical processes at cold seeps – Challenges in recent and

ancient systems. Varna, Bulgaria, 28-30 September 2009

7. Regnier, Pierre (Utrecht University) Foreign advisory committee member: MERMEX (Marine Ecosystems

Response in the Mediterranean Experiment) project consortiumCNRS, CEREGE, Europole de l’Arbois, Aix

en provence,France, 22-23 September 2009

8. Regnier, Pierre (Utrecht University) Invited scientific expert. 1st scientific meeting on the chemical Evo-

lution of Lake Kivu. Royal Museum for Central Africa. Tervuren, Belgium, 19 January 2009

9. Regnier, Pierre (Utrecht University) Steering committee member. KAUST-GRP Center in Developmen-

tSOWACOR (Saudi Arabia). Utrecht, The Netherlands, 18-19 May 2009


1. Conley, Daniel (Lund University) HELCOM Ministers meeting, Parliment, Stockholm, Sweden, 25 August

2010

2. Conley, Daniel (Lund University) IVL Swedish Environmental Research Institute, The Swedish Royal Insti-

tute of Technology, Stockholm Sweden (followed by a interview on Swedish Radio), 2 September 2010

3. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) EU Coordinated Action "Deep Sea

and Sub-Seafloor Frontiers", Member of Steering Committee, Kick-off meeting, Brussels, 1 day 2010

4. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Advisory Board, Alfred

Wegener Institute for Marine and Polar Research, Bremerhaven, Germany, 2-day Meeting in Bremerha-

ven 2010

5. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Advisory Board, Faculty

of Biology, University of Vienna, Austria, 2-day Meeting in Vienna 2010

6. Pimenov, Nikolay (Winogradsky Institute of Microbiology, Moskow) Scientific steering comities of 10th

International Conference on Gas in Marine Sediments. Limnological Institute SB RAS (Listvyanka Lake

Baikal), 06-12 September, 2010

7. Regnier, Pierre (Utrecht University) Invited scientific Expert. ICES meeting on ‘How Models help us to

understand Climate Change Evolution and Impacts in the Regional Oceans (WKMCCEI)’. Brussels, Bel-

gium, 12–14 January 2010

8. Regnier, Pierre (Utrecht University) Foreign advisory committee member: MERMEX (Marine Ecosystems

Response in the Mediterranean Experiment) project consortium CNRS. World Trade Center Marseille,

France, 8-9 July 2010,

9. Regnier, Pierre (Utrecht University) Advisory committee member: Advanced modeling and research on

eutrophication (AMORE III), Belgian Science Policy. Brussels, Belgium, 6 October 2010.

10. Regnier, Pierre (Utrecht University) Invited scientific expert. High-level workshop on living in a low-

carbon society. Atomium Culture, the permanent platform for European Excellence. Brussels, Belgium,

18-19 November 2010

11. Rehder, Gregor (Baltic Sea Research Institute Warnemünde) Member of the organizing scientific com-

mittee of The National Academy of Science/ Humbolt Foundation (German American Frontiers of Sci-

ence/ Kavli Conference) October 2010

59

12. Sivkov, Vadim (Shirshov Institute of Oceanology, Atlantic Branch, Kaliningrad) Scientific steering com-

mittee member of International symposium ”Mining and processing of the amber in Sambia”, Kalinin-

grad. 12-14 May 2010


mittee member of International Conference ”Multiphase systems: the World ocean, environment, hu-

man, society, technologies”, Shirshov Institute of Oceanology, onboard R/V Academik Sergey Vavilov, 7-

14 June 2010


1. Brüchert, Volker (Stockholm University) Swedish Nuclear Waste and Management Company (SKB) Origin

of methane in groundwater discharge near sites of long-term nuclear waste disposal in Sweden 2011

2. Ferdelman, Timothy (Max Planck Institute, Bremen) served as a steering committee member on the EU

FP7 Deep Sea and Sub-seafloor Frontier Coordinated Action. He was also a member of the IODP Proposal

Evaluation Panel 2011

3. Ferdelman, Timothy (Max Planck Institute, Bremen) also served on the PhD committee of BONUS doc-

toral student Zsusanna Toth, which met twice in 2011

4. Fossing, Henrik (Inst. Bioscience, Aarhus University) BONUS Forum 2011, Gdansk, Poland, 24 October

2011

5. Fossing, Henrik (Inst. Bioscience, Aarhus University) 13th Baltic Development Forum Summit and Euro-

pean Commision’s 2nd

Annual Forum on the Strategy for the Baltic Sea Region, Gdansk, Poland, 24-26

October 2011

6. Klusek, Zygmunt (Institute of Oceanology, Polish Academy of Science, Gdansk) Scientific Committee, 8th

EAA International Symposium on Hydroacoustics - XXVIII Symposium on Hydroacoustics, Jurata, Poland,

17-20 May 2011

7. Regnier, Pierre (Utrecht University) Committee member. Section Earth and Life Sciences (ALW), Dutch

Science Foundation (NWO). 1 day meeting, 2011

8. Regnier, Pierre (Utrecht University / Université Libre de Bruxelles) Committee member. Section Sciences

Exactes et Naturelle. Fonds National de la Recherche Scientifique (National Research Fund for Scientific

Research – FNRS). Belgium. 1 day meeting 2011


mittee member of International Conferense (School) on marine geology, Moscow, 14-18 November

2011

2011 - contribution to consultations carried out by the European Commission

1. Regnier, Pierre (Utrecht University / Université Libre de Bruxelles) The Baltic Gas project. Bonus + high-

lights to the European community. Brussels, Belgium. 8 November 2011.

6.1 Other related activities

The Danish Crown Prince Frederik and his wife, Crown Princess Mary, visited The Leibniz-Institute for Baltic Sea

Research, Warnemünde (IOW) on September 28, 2010. The Danish Ambassador in Germany and rep-

resentatives from Germany and Denmark at ministerial level participated in the visit. On this special occasion a

booklet on Danish-German research collaborations in marine sciences was published by the Royal Danish Em-

60

bassy, with preface written by Denmark's Minister for Science, Technology and Innovation. The booklet specifi-

cally mentions collaboration within the BONUS project BALTIC GAS.

The Maria S. Merian cruise MSM 16/1 (July 31 – August 21, 2010) was presented to the public through weekly

reports, blogs and press releases and received significant public interest. Also, a small group of visitors was wel-

comed on board the research vessel for a 12 hour cruise through the Kiel Canal (German: Nord-Ostsee-Kanal) by

the end of the cruise.

7. Meetings and conferences

Brüchert, V., D. Bastviken, L. Ginters. Sediment-water and sea-air fluxes of methane along a salinity and eutroph-

ication gradient in the coastal Baltic Sea. Fall Meeting American Geophysical Union, San Francisco, Decem-

ber 5-9, 2011

Brüchert, V., L. Ginters, D. Bastviken, T. M. Nguyen, T. G. Ferdelman. Methane dynamics in Himmerfjärden, Baltic

Sea. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, August 22-26 2011

Brüchert, V., L. Ginters, D. Bastviken, T. M. Nguyen, T. G. Ferdelman. Methane dynamics in Himmerfjärden, Baltic

Sea. Visions of the Sea Conference 2011. The Swedish Society for Marine Sciences. Royal Swedish Academy

of Sciences, Stockholm, November 21-23 2011

Brüchert, V., T. Nguyen, A. Deutschmann, M.E. Boettcher, T.G. Ferdelman. Bacterial sulfate reduction and meth-

anogenesis in oligotrophic sediments of the northern Baltic. European Geoscience Union, EGU 2010, Vienna,

2-7 May 2010

Conley, D.J. Effect of hypoxia on nutrient biogeochemistry in the Baltic Sea. 2011 ASLO Aquatic Sciences Meeting,

San Juan, Puerto Rico, USA, 13-18 February 2011

Conley, D.J. Hypoxia in the Baltic Sea. Nereis Park Conference, Kristineberg, Sweden, 29-31 August 2011

Conley, D.J. Time series of oxygen concentrations in the Baltic Sea. Coastal and Estuarine Research Federation

Meeting, Daytona Beach, FL, USA, 6-10 November 2011

Endler, R., J. Wunderlich, J. Schneider von Deimling, S. Erdmann. Acoustic imaging of shallow gas in Baltic Sea

sediments. Int. Conf. HYDRO 2010, Warnemünde, 2-5 November 2010

Flury, S., H. Fossing, H. Røy, M. Lever, B. Gribsholt and B. B. Jørgensen. Enhanced methane fluxes in gassy sedi-

ments - a paradox? 10th International Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal,

Russia, 6-12 September 2010

Flury, S., H. Fossing, H. Røy, J.B. Jensen, A. Dale, B.B. Jørgensen. Geochemical dynamics along a transect of gas-

free and gas charged sediments – A detailed study in Aarhus Bay. 8th Baltic Sea Science Congress, Skt. Pe-

tersburg, Russia, 22-26 August 2011

Fossing, H., T.G. Ferdelman, L. Lapham, S. Flury, B.B. Jørgensen, J.B. Jensen, R. Endler, J. Mogollon. Methane

concentrations along a transect crossing an area with free methane gas (Bornholm Basin, Baltic Sea). 8th

Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-26 August 2011

Gentz, T., M. Schlüter. Underwater cryotrap - membrane inlet system (CT-MIS) for improved in situ analysis of

gases by mass spectrometry. 8th Harsh-Environment Mass Spectrometry Workshop, St. Petersburg, USA,

19-22 September 2011

Gentz, T., M. Schlüter, R. Martinez. Identification of the regional distribution of gassy sediments in the Baltic Sea

by application of Geo-Information-Systems. Bonus Annual Conference 2010, Vilnius, 19-21 January 2010

61

Gülzow, W., G. Rehder, J. Schneider v. Deimling, T. Seifert. Seasonal and spatial distribution of methane in the

surface water of the Baltic Sea. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, August 22-26 2011

Gülzow, W., G. Rehder, B. Schneider, J. Schneider v. Deimling, B. Sadkowiak. Continuous measurement of me-

thane and carbon dioxide concentrations in surface waters based on off-axis integrated cavity output spec-

troscopy Fall Meeting American Geophysical Union, San Francisco, USA. December 13-17 2010

Gülzow, W., G. Rehder, B. Schneider, J. Schneider von Deimling, B. Sadkowiak. A new method for continuous

measurement of methane and carbon dioxide in surface waters of the Baltic Sea using off-axis integrated

cavity output spectroscopy (ICOS). Geophysical Research Abstracts Vol.12, EGU 2010-2913, EGU General As-

sembly, Vienna, May 2-7 2010

Jakobs, G., O. Schmale, M. Blumenberg, G. Rehder. Indications for microbially mediated methane oxidation in the

water column of the central Baltic Sea (Gotland Deep and Landsort Deep). 8th Baltic Sea Science Congress,

Skt. Petersburg, Russia, August 22-26 2011

Jensen J.B. 2010. Major tectonic control of near bottom current sedimentation and methane distribution in the

Bornholm basin, South-Western Baltic Sea. The 10th International Marine Geological Conference ”The Baltic

Sea Geology - 10”, St.Petersburg, Russia, 24-28 August 2010

Jørgensen, B.B. Havbundens metanproduktion – fra Østersøen til verdenshavet. Dansk Havforskermøde, 28 Janu-

ary 2009

Jørgensen, B.B. The dynamic methane cycle in marine sediments. University of Cardiff, 5 May 2009

Jørgensen, B.B., T.G. Ferdelman, S. Flury, H. Fossing, L. Holmkvist, L. Lapham. Controls on methane formation in

Baltic Sea sediments. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, August 22-26 2011

Jørgensen, B.B., S. Flury, H. Fossing, L. Holmkvist, J.B. Jensen, R.J. Parkes and the BALTIC GAS team. 2010. BALTIC

GAS: Dynamic methane fluxes in the seabed. 10th International Conference on Gas in Marine Sediments,

Listvyanka, Lake Baikal, Russia, 6-12 September 2010

Jørgensen, B.B., H. Fossing and the BALTIC GAS team. BALTIC GAS: The dynamic methane fluxes in the seabed.

Bonus Annual Conference 2010, Vilnius, 19-21 January 2010

Jørgensen, B.B. A cryptic sulfur cycle driven by iron in the methane zone of marine sediment (Aarhus Bay, Den-

mark). EGU General Assembly, Vienna, Austria, 5-7 April 2011

Klusek, Z., P. Majewski. Acoustics methods used in shallow gassy sediments: detection and classification in the

Baltic Sea PEEZ. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-26 August, 2011

Klusek, K., P. Majewski. Acoustics detection and classification of shallow gas in sediments in the Gulf of Gdansk.

58th Open Seminar on Acoustics joint with 2nd Polish-German Structured Conference on Acoustics, Jurata,

Poland, 13-16 September 2011

Lapham, L., S. Flury, H. Fossing, V. Brüchert, T. Ferdelman, N.M. Thang, L. Ginters, B.B. Jørgensen. Using stable

carbon isotope ratios of CH4 and CO2 to follow the production and consumption of CH4 along the south to

north salinity gradient in the Baltic Sea. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-26 Au-

gust 2011

Mogollón, J.M., A. Dale, P. Regnier. Modeling the Holocene methane cycle in Arkona Basin sediments. 10th Inter-

national Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia, 6-12 September 2010

Mogollón, J.M., A. Dale, P. Regnier. Methane cycling in the Baltic Sea: Hindcast modeling at the 10 kyr timescale.

Workshop on uncertainties of scenario simulations, Norrköpping, Sweden, 14 October 2010

Mogollón, J.M., A.W. Dale, P. Regnier, M. Schlüter. Methane oxidation rates in gassy areas across the North Sea,

Baltic Sea transition. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia 22-26 August 2011

62

Pimenov, N.V., T.A. Kanapatsky, P.A. Sigalevich, A.G. Grigoriev, V.A. Zhamoida. Microbial processes of carbon and

sulfur cycling in the Holocene sediments of the Vyborg Bay (Finland Gulf, Baltic Sea). 8th Baltic Sea Science

Congress, Skt. Petersburg, Russia, 22-26 August 2010

Pimenov, N.V., T.A. Kanapatsky, P.A. Sigalevich, A.G. Grigoriev, V.A. Zhamoida. Microbially mediated methane

and sulfur cycling in gas-bearing sediments of the Vyborg Bay (Finland Gulf, Baltic Sea). 10th International

Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia, 6-12 September 2010

Regnier, P. (invited) Marine methane flux and climate change: From biosphere to geosphere. ICES workshop on

models and regional climate change, Brussels, Belgium, January 2010

Regnier, P. (invited) Modeling biosphere-geosphere interactions: CO2, CH4 and the global seafloor carbon cycle.

Introductory Lecture. Belgian Geological Society Annual Meeting, Leuven, Belgium, February 2010

Regnier, P. Continental and marine sources and sinks of methane in the context of climate change. Theme leader

working group 3. Workshop ‘Exploring Knowledge gaps along the gobal carbon route’. Rochefort, Belgium,

October 4-7 2011

Regnier, P., P. Friedlingstein, F.J. Ciais, F. Mackenzie, M. Thullner, P. Van Cappellen. Exploring Knowledge gaps

along the global carbon route: A hitchhiker’s guide for a boundless cycle. Plenary presentation/ Plenary lec-

ture. Royal Academy of Sciences. Brussels, Belgium, October 4 2011

Rehder, G., H. Fossing, L. Lapham, R. Endler, V. Spiess, V. Bruchert, T. Nguyen, W. Gülzow, J. Schneider von

Deimling, D. Conley, B. Jørgensen. Methane fluxes and their controlling processes in the Baltic Sea. Fall

Meeting American Geophysical Union, San Francisco, USA. December 13-17 2010

Rehder, G., L. Lapham, H. Fossing, W. Gülzow, J. Schneider von Deimling, R. Endler, V. Spiess, J.B. Jensen, V.

Bruechert, T. Ferdelmann, O. Schmale, J. Virtasalo, D. Conley, T. Neumann, T. Leipe, S. Flury, Z. Toth, B.B.

Jørgensen, and the MSM 16/1shipboard scientific party. Shallow gas occurrences, methane fluxes and their

controlling processes in the Baltic. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-26 August

2011

Schneider v. Deimling, J. Gas Mapping using Multibeam Mapping Sonar. Int. Conf. HYDRO 2010, Warnemünde,

2-5 November 2010

Schneider v. Deimling, J., W. Weinrebe, D. Bürk, Z.Thot, R. Endler, H. Fossing, V. Spiess, G. Rehder. Subbottom

mapping of shallow gas using medium to low frequency multibeam sounders. Fall Meeting American Geo-

physical Union, San Francisco, USA. December 13-17 2010

Sivkov, V., D. Dorokhov, T. Kanapatsky, N. Pimenov. Gas-Bearing Sediments of the South-eastern Baltic Sea:

Acoustical and Gas-Geochemical Investigation. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-

26 August 2011

Thang, N.M., V. Brüchert, M. Fomolo, G. Wegener, M. Reinholdsson, L. Ginters, B.B. Jørgensen, T.G. Ferdelman.

Biogeochemistry of methane and sulfate in Himmerfjärden estuary sediment, Sweden. EGU General Assem-

bly, Vienna, 3-9 April 2011

Thang, N.M., M. Formolo, S. Flury, B.B. Jørgensen, T.G. Ferdelman. Biogeochemistry of sulfur in Gdansk Bay sed-

iments (Baltic Sea). EGU General Assembly, Vienna, 3-9 April 2011

Tóth, Z., N. Allroggen, V. Spiess. Geoacoustic characterization of and estimation of the shallow gas content in

Baltic Sea sediments. 8th Baltic Sea Science Congress, St. Petersburg, Russia, 22-26 August 2011

Tóth, Z., N. Allroggen, V. Spiess (2011) Geoacoustic properties of shallow gas accumulations in Baltic Sea sedi-

ments – which can be used for quantification? 2nd Young Scientist Excellence Cluster Conference on Marine

and Climate Research, Bremen, Germany, 4-5 October 2011

63

Tóth, Z., J. Schneider von Deimling ,V. Spiess. Distribution of shallow gas accumulations in the sediments of the

Mecklenburg Bay, Baltic Sea; based on multi-frequency seismo-acoustic mapping. Mátrafüred, Hungary, 26-

27 March 2010

Tóth, Z:, V. Spiess. Geoacoustic characterization of shallow gas accumulations in marine sediments. Bremen PhD

days in Marine Sciences 2011, University of Bremen, Bremen, Germany, 13-14 April 2011

Tóth, Z., V. Spiess. Multi-frequency seismo-acoustic imaging of shallow free gas in the southwestern part of the

Baltic Sea. 10th International Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia, 6-12

September 2010

Ulyanova M., D. Dorokhov (in Russian) Gas-bearing sediments distribution in Gdansk Deep, the Baltic Sea. In: Sea

and ocean geology: Materials of XVIII International scientific Conference (School) on marine geology. Vol. II,

p. 102-104, 16-18 November 2009

Ulyanova M., T. Kanapackiy (in Russian) Methane fluxes in sediments of the Gdansk Basin, the Baltic Sea. In: Sea

and ocean geology: Materials of XVIII International scientific Conference (School) on marine geology, p.116-

117, 16-18 November 2009

Ulyanova, M., T. Kanapatsky, D. Dorokhov, V. Sivkov, N. Pimenov (2011) Gas-Bearing Sediments of the South-

eastern Baltic Sea: Acoustical and Gas-Geochemical Investigation. In: Book of Abstracts of 8th Baltic Sea

Science Congress, p 113

Ulyanova, M., V. Sivkov, D. Dorokhov. (2010) Gas-bearing sediments distribution in the Baltic Sea based on

acoustical data. 10th International Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia,

6-12 September 2010

Ulyanova, M., V. Sivkov, D. Dorokhov, T. Kanapatsky, N. Pimenov (2011) Gas-bearing sediments of the south-

eastern Baltic Sea: acoustical and gasgeochemical investigation, 8th Baltic Sea Science Congress, Skt. Pe-

tersburg, Russia, 22-26 August, 2011

8. Peer reviewed scientific papers

Gülzow, W., G. Rehder, B. Schneider, J. Schneider v. Deimling, B. Sadkowiak (2011) A new method for continuous

measurement of methane and carbon dioxide in surface waters using off-axis integrated cavity output spec-

troscopy (ICOS): An example from the Baltic Sea. Limnology Oceanography Methods, 9, p 168-174

Majewski, P. Z. Klusek (2011) Expressions of shallow gas in the Gdansk Basin. Zeszyty Naukowe Akademii

Marynarki Wojennej, ISSN 0860-889X, vol. 51, No 4

Mogollón, J.M., A.W. Dale, I. L’Heureux, P. Regnier (2011) Impact of seasonal temperature and pressure changes

on methane gas production, dissolution, and transport in unfractured sediments marine sediments. Journal

of Geophysical Research, 116, G03031, 17 pp

Mogollón, J.M., A.W. Dale, H. Fossing, P. Regnier (2011) Timescales for the development of methanogenesis and

free gas layers in recently-deposited sediments of Arkona Basin (Baltic Sea). Biogeosciences Discussions, 8, p

7623-7699

Pimenov N.V., M.O. Ulyanova, T.A. Kanapatsky, E.F. Veslopolova, P.A. Sigalevich, V.V. Sivkov (2010) Microbially

mediated methane and sulfur cycling in pockmark sediments of the Gdansk Basin, Baltic Sea. Geo-Marine

Letters, 30, p 439-448

Regnier, P., S. Arndt, A.W. Dale, D.E. LaRowe, J. Mogollon, P Van Cappellen, P (2011) Advances in the biogeo-

chemical modeling of the marine methane cycle. Earth Science Reviews 106, p 105-130

64

Schmale, O, J. Schneider v. Deimling., W. Gülzow, G. Nausch, J. Waniek, G. Rehder (2010) The distribution of

methane in the water column of the Baltic Sea. Geophysical Research Letters, 37, L12604,

Schneider von Deimling, J., C. Papenberg (2011) Technical Note: Detection of gas bubble leakage via correlation

of water column multibeam images, Ocean Science Discussions, 8, p 1757-1775

Schneider von Deimling, J., G. Rehder, D.F. McGinnnis, J. Greinert, P. Linke (2011) Quantification of seep-related

methane gas emissions at Tommeliten, North Sea. Continental Shelf Research, 31, p 867-878

Steckbauer, A., C.M. Duarte, J. Carstensen, R. Vaquer-Sunyer, D.J. Conley (2011). Ecosystem impacts of hypoxia:

thresholds of hypoxia and pathways to recovery. Environmental Research Letters, 6, 025003, 12pp

9. Submitted scientific papers

Dale, A.W., S. Flury, P. Regnier, H. Røy, H. Fossing, B.B. Jørgensen (submitted) Coupling between methanogene-

sis, anaerobic oxidation of methane and δ13C distributions in gassy sediments from the Baltic Sea (Aarhus

Bay). Geochimica et Cosmochimica Acta

Flury, S., A.W. Dale, H. Røy, H. Fossing, J.B. Jensen, B.B. Jørgensen (submitted) Methane fluxes and shallow gas

formation controlled by Holocene mud thickness in Baltic Sea sediments. Geochimica et Cosmochimica Acta

Gentz, T., M. Schlüter (submitted) Underwater cryotrap - membrane inlet system (CT-MIS) for improved in situ

analysis of gases. Limnology Oceanography Methods

Gülzow, W., G. Rehder, B. Schneider, J. Schneider v. Deimling, B. Sadkowiak (submitted) A new method for con-

tinuous measurement of 1 methane and carbon dioxide in surface waters of the Baltic Sea using off-axis in-

tegrated cavity output spectroscopy (ICOS). Limnology Oceanography Methods

Pimenov, N.V., T. A. Kanapatskii, P.A. Sigalevich, I.I. Rusanov, E.F. Veslopolova, A.G. Grigorev, V.A. Zhamoida (in

pres; 2012) Sulfate Reduction, Methanogenesis, and Methane Oxidation in the Holocene Sediments of the

Vyborg Bay, Baltic Sea. Microbiolog, 81

10. Statistics for the performance assessment of the Programme

BALTIC GAS principal scientists used the BONUS EPSS - Electronic Proposal Submission System to report Statistics

and research infrastructures:

Statistics for the performance assessment of the Programme

1 Number of times your project has contributed to consultations carried out by European Commis-

sion. (Provide more information in annual and final reports) 1

2 Number of times the scientists working in your Project have served as members or observers in

stakeholder and scientific committees. (Provide more information in annual and final reports) 31

3 Number of times the effort of your Project has resulted in modifications made to relevant policy

documents and action plans (in particular, Baltic Sea Action Plan). (Provide more information in

annual and final reports)

0

4 Number of times the effort of your Project has resulted in modifications made to relevant policy

documents and action plans (in particular, Baltic Sea Action Plan). (Provide more information in

annual and final reports)

0

5 Number of persons (above) and working days (below) spent by foreign scientists on research ves-

sels participating in the cruises arranged by your Project

51

301

65

6 Number of persons (above) and working days (below) spent by foreign scientists using other major

facilities involved in your Project

14

36

7 Number of popular science papers produced by your Project 3

8 Number of interviews to media given by members of your Project's consortium 29

9 Number of multi-media products and TV episodes produced by your Project with dissemination

purpose 5

10 Number of other dissemination products produced by your Project 10

11 Number of times your Project team has issued a recommendation how to improve general public's

comprehension and priorities regarding the Baltic Sea 3

12 Number of times your project has contributed to dissemination products/events addressed to

general public concerning coupling between marine environmental quality and human health and

well-being

9

13 Number of datasets your project has delivered to the common metadata base of the Programme 87

14 Number of scientists that attended international workshops, WG meetings, conferences, intercali-

bration exercises etc. paid by BONUS+ 135

15 Number of PhD courses (above) organized by your Project and persons participating (below) 6

49

16 Number of modifications made to current PhD course programmes that resulted from the work of

your Project 7

17 Number of student visits (persons above, visit days below) from your Project to other BONUS pro-

jects

9

80

Significant research infrastructures jointly used by the Project consortium

1. Description: Askö Marine Research Station (Stockholm University) incl. RV Limada

Purpose: Himmerfjärden: Sediment and water column + laboratory experiments. 12-18.6, 09-

15.8, 06-12.9, 2010

Amount of use: 6 days cruise days / 12 laboratory days

In-kind contribution: 3,300 EUR

2. Description: Askö Marine Research Station (Stockholm University) incl. RV Limanda

Purpose: Himmerfjärden: Sediment and water column incl. laboratory experiments. 12-17.5,

2009

Amount of use: 2 days cruise days / 4 laboratory days


3. Description: RV Alkor Atlas fansweep multibeam EK60 echosounder multichannel streamer boomer

GI gun magnetometer heat flow probe data acquisition equipment

Purpose: Mecklenburg and Arkona Bays: mapping and quantification of gas in sediment and

water column

Amount of use: 7 days


4. Description: RV Alkor Atlas fansweep multibeam EK60 echosounder multichannel streamer boomer

GI gun magnetometer heat flow probe data acquisition equipment

Purpose: Mecklenburg and Arkona Bays: mapping and quantification of gas in sediment and

water column

66



5. Description: RV Ladoga

Purpose: Finland Gulf (Vyborg Bay): Crater-like structures and gas-saturated sediments. 30.06-

03.07.2009

Amount of use: 4 days, 6 scientists


6. Description: RV Maria S Merian Cruise 16/1

Purpose: Western Baltic Sea, Gulf of Bothnia: CH4 distribution in sediments and water column.

31.7-21.8, 2010



7. Description: RV Nawigator XXI geophysical data acquisition systems shallow water multichannel

streamer GI gun side scan sonar

Purpose: Western Baltic: Mapping and quantification of gas in sediment and water column. 15-

27.7, 2010



8. Description: RV Oceania Chirp echo sounder 'nonlinear acoustic' echo sounder

Purpose: Gulf of Gdansk: gas-saturated sediments. 08-13.4, 2010

Amount of use: 6 days, 5 scientist,


9. Description: RV Oceania Chirp echo sounder 'nonlinear acoustic' echo sounder

Purpose: Southern Baltic: gas-saturated sediments and gaseous structures (e.g. pockmarks). 17-

30.4 2010

Amount of use: 2 days allocated for 2 BALTIC GAS scientists


10. Description: RV Poseidon (cruise 392)

Purpose: Baltic Sea: shallow gas and methane distribution in sediments and water column.

27.11.-17.12, 2009



11. Description: RV Professor Shtockmann

Purpose: Russian Sector of Gdansk Basin and Gotland Deep: Gas-saturated deposits. 20-

27.06.2010


67


12. Description: RV Safira Chirp echo sounder 'nonlinear acoustic' echo sounder

Purpose: Gulf of Gdansk: Gas-saturated sediments. 16-19.10, 2010

Amount of use: 1 day allocated for 1 BALTIC GAS scientist

In-kind contribution: 500 EUR

13. Description: RV Shelf

Purpose: Russian sector of Gdansk Basin: Pockmarks and gas-bearing sediments. 04-10.09, 2009



14. Description: RV Susanne A

Purpose: Sediment sampling Aarhus Bay. 04.5, 2010

Amount of use: 1 day, 5 scientists


15. Description: RV Susanne A

Purpose: Sediment sampling Aarhus Bay. 5.10, 2009

Amount of use: 1 day, 5 scientists


baltic gas final scientific report · final scientific report reporting period: january 1, 2009 –...

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