Baupte progress

meeting8 – 10/11/04

« Earth Science Institute of Orleans », France UMR 6531 of CNRS – University of Orleans

Fatima LaggounLaure Comont

Jean-Robert DisnarMarielle Hatton

WP 05: Physical and chemical quality of peat organic matter

1. Determine bulk characterictics (FTIR and C & N contents) of peat along various profiles at the different sites and their potential as indicators of peat quality.

2. Determine the degradation processes of peat organic matter (physical structure and biomarkers) in pristine and cut-over sites in relation to microbial communities and vegetation keystone-species.

3. Assess experimentaly the decomposition kinetics of plant tissues into geopolymers so as to define the most favourable conditions for long-term sequestration of C in restored peatlands.

Objectives:

all WP1 samples run and preliminary data analysis performed

I. Bulk peat characteristics

C, N contents:

Micromorphology and organic constituent countings

all WP1 samples have been completed and data analysis finished

FRA : bare peat

RUSSEY

cumulative % of org.const.C/N ratio

density(g/cm3)

Replicate 3

cumulative % of org.const.

C/N ratiodensity(g/cm3)

Replicate 2

-Higher density in the top of « old » peat

- C/N ratios ≈ constant

-Comparable organic composition, except the higher % of mucilage in FRB associated to micro-organism %.

FRB : 1st regeneration stage

Regenerating peat ?

FRC: 2nd regeneration stage

cumulative % of org.const.

C/N ratiodensity(g/cm3)

cumulative % of org.const.

C/N ratiodensity(g/cm3)

RUSSEY

Replicate 3 Replicate 2

? ?

Regenerat.peat?

FRD : intact area

-Considering density, C/N, org const. evolution => limit between « old » peat and regenerat. peat ≈ 20-25cms

- regenerating peat: a nice plant succession ! heterogeneous org. composition

-Bulk characteristics of FRD’s OM strangely similar to that of FRC ? Except the more homogeneous composition of uppermost peat (Sph. mainly)

FBB : bare peat

BAUPTE

cumulative % of org.const.C/N ratio

density(g/cm3)

Replicate 3

- Higher density in superficial peat levels (3 & 4) correlated (for FBA) with lower C/N ratios => higher degradation ?

- FBB: homogeneous composition.

- FBA: more heterogeneous with high % of AOM & microorg. - well-correlated with high C microbial biomass in level 3 (see WP06 results).

cumulative % of org.const.

C/N ratio density(g/cm3)

Replicate 1

FBA : E.angustifulium

CHA : fen

CHB : transitional

CHAUX D’ABEL

cumulative % of org.const.

C/N ratiodensity(g/cm3)

Replicate 2

cumulative % of org.const.

C/N ratiodensity(g/cm3)

Replicate 3

-CHA and CHB: similar OM properties

-In CHB: better delimitation of regenerating peat

-In both sites: OM of regenerating peat mainly composed of sphag. & Cyper. tissues

Regenerat.peat?

CHC : bog

CHD : Intact

cumulative % of org.const.

C/N ratiodensity(g/cm3) cumulative %

of org.const.C/N ratiodensity(g/cm3)

CHAUX D’ABEL

Replicate 1 Replicate 1

?

??

- however, in CHC: uppermost peat mainly composed of sphagna

- the limit between « old » peat & regener. peat: not very clear

-OM composition: homogeneous, except level 5: higher degradation ?

- Intact zone: a lot of missing uppermost samples to conclude anything

SCOTLAND SCA: bare peat SCC: 1st regen. stage (Eriophorum)

- C/N ratios well correlated to degradation index - Organic composition ≈ similar in SCA & SCC - In uppermost levels at SCC: high % of AOM, root tissues and Fungi => higher degradation in microsites associated to Eriophorum roots ?

Degradation index= Unstructureless OM (Unstructureless OM + Structureless tissues)

SCD: 2nd regen. stage (mixed vegetation)

SCB: 1st regen. stage (Sphagna)

- However, in regenerated « young » peat, the organic composition at SCB and SCD is quite similar (at the top of SCD, more AOM), and once again, more heterogeneous than that of SCC

Regenerat.peat?Regenerat.peat?

FINLAND FIE: bare peat

FIC: C.rostrata (wet)

- As observed for some other sites, the uppermost levels of FIE & FIC have low C/N ratios and high % of AOM => higher OM degradation

-In deeper levels, OM is mainly composed of mucilage: to be correlated with microbial groups (Daniel G. & Edward M. analyses ?)

FIB: Er.vaginatum (dry) FIA: Er.vaginatum (wet)

FID: Sphagnum (wet)

- FIB & FIA present similar OM composition exept for the dried situation (FIB) which, strangely, presents better preservation of Cyperacea tissues.

- Need more information on the regeneration trend ? When the peat exploitation stopped ?...

?

For all sites:

- uppermost levels of the « old » peat (present (FRA) or ancient (FRC)) characterised by higher densities correlated to lower C/N ratios.

- regenerating « young » peat characterised by heteregeneous composition in the first regeneration stages, and more homogeneous in the latter ones.

At least at Baupte, La Chaux d’Abel and scottish sites:

high values of C/N in microbial biomass seem to be correlated to high relative pourcentages of (AOM+mucilage) i.e., structureless inheritant material and micro-organism secretions) – to be confirmed ?

Peat organic matter composition Preliminary conclusions

II. Peat organic matter degradation processes

all samples have been completed and data analysis finished except for FRB & CHB.

Particle size fractionation (200µm)

identification of biomarkers

Completed for:- Living plants (see Hyytiälä presentation)- Fine fraction: FR and FBIn progress:- Finnish, scottish and CH samples

0

10

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30

40

50

60

70

0,00 0,05 0,10 0,15 0,20 0,25

density (g/cm3)

% w

t (fin

ed fr

actio

n)

FRA FRC FRD

r2 ≈ 0.59

Correlation between %wt of fine fraction (<200µm) and bulk density:an example

- globally, positive correlation between the proportion of peat fine fraction and bulk density- correlation coefficient is not very high

BAUPTE - Sugar analyses of fine fraction <200μmFBB: bare peat FBA: 1st regener. stage (Er. angustifolium)

Total sugars of Erioph. ≈ 320 mg/g

-evolution with depth of total sugar contents: ≈ constant (50 mg/g)

-Similar distribution of hemicellulosics at FBB & FBA dominance of arabinose and xylose => vascular plant sources

- low % of cellulosic glucose => attests a higher degradation

FRA: bare peat

RUSSEY - Sugar analyses of fine fraction <200μmFRC: 2nd regeneration stage

Total sugars of living plants ≈ 367 mg/g

-FRA: evolution with depth of total sugar contents: ≈ constant the same for the distribution of hemicellulosic sugars. These are dominated by H. glucose which could derive in part from micro-organism secretions.

-FRC: regenerated peat: total sugar content ≈ FRA markers of Cyper. & Sphagna less % of H. glucose => better preservation ?

FRD: intact area Total sugars of living plants ≈ 367 mg/g

RUSSEY - Sugar analyses of fine fraction <200μm

Progressive consumption of total sugars with depth correlated with:-progressive increasing of H. glucose -Progressive increasing of degradation index

0

50

100

150

200

250

300

350

400

450

0,10 0,20 0,30 0,40 0,50 0,60 0,70

cellulosics/total sugars

Tot

al S

ugar

s (m

g/g)

FRD FRC FRA FBA FBB Cyperaceae Polytrichum sphagna

RUSSEY BAUPTE Living plants

7

87

5

4

?

64 3 5

3

4

678

6

5

8

polyt

sph cyp

Sugar analyses of fine fraction <200μm

Chaux d’Abel (sampling of nov.2001)

0

50

100

150

200

250

300

350

400

450

0,10 0,20 0,30 0,40 0,50 0,60 0,70

cellulosics/total sugars

To

tal s

ug

ars

(m

g/g

)

CA5 CA6 CA1 Cyperaceae Polytrichum sphagna

3

4 5

68

5

7 8

3

6

45

7

8

43

6

polyt

sph

cyp

≈ CHC ≈ CHD ≈ CHA

Sugar analyses of bulk peat

Identification of biomarkersPreliminary conclusions

Bare peat: - no significative evolution with depth(Baupte ~ 50 mg/g while Le Russey ~ 200 mg/g)

- high quantity of H. glucose partly derived from microbial secretion ? (to be compared with data of microorganism groups)

Regenerating peat:even in fine fraction source biomarkers are dominant (arabinose, galactose and xylose)

(not enough data to conclure on degradation biomarkers; CH, SC & FI in progress)