air quality monitoring - western cape · 2011. 8. 10. · ambient air quality monitoring report st...

Air Quality Monitoring

Monthly Report

Directorate: Pollution Management

Sub-directorate: Air Quality Management

ST. HELENA BAY

Ambient Air Quality Monitoring Report

St Helena Bay – Western Cape

April 2011

Prepared for

Department of Environmental Affairs and Development Planning

AQ205

SGS Environmental

1st Floor, Panther Park, 11 Berkley Road Maitland, Cape Town, 7405

Tel: +27 21 506 3280 Fax: +27 31 279 1414

Internet: www.sgs.com E-mail: [email protected]

DEPARTMENT OF ENVIRONMENTAL AFFAIRS AND DEVELOPMENT PLANNING AQ205 Monthly Ambient Air Quality Report for St Helena Bay, April 2011

EXECUTIVE SUMMARY

This report covers data from the St Helena Bay Air Quality Monitoring station for April 2011.

This station is one in an ambient network of four (4) additional stations that will be

commissioned across the Western Cape by SGS Environmental on behalf of the Provincial

Government of the Western Cape.

This is the first report for the St Helena Bay monitoring station which was commissioned on

28th March 2011.

The WHO odour threshold (7ug/m3 for 30-minute mean) was exceeded on seven days

during April 2011 (see Fig 4.1.2 for more details).

Data collection for H2S at the St Helena monitoring station was 63% for April 2011 due to on

site power problems between 22nd April and 2nd May 2011.

No CO2 data is available for April 2011 as the analyser was only installed in May 2011.

The meteorological station was installed on 4th May 2011 and no data is available for April

2011.

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REPORT DETAILS REFERENCE AQ205/wc7/201104 REPORT TITLE Ambient Air Quality Monitoring Report, April 2011 DATE SUBMITTED: 27 May 2011 CLIENT: Provincial Government of the Western Cape

Department of Environmental Affairs & Development Planning: Deputy Director (Air Quality Monitoring) 1 Dorp Street Cape Town 8001 Tel: +27 21 483 2891 E-mail: [email protected]

PREPARED BY: Helen Hill 1st Floor, Panther Park, 11 Berkley Road Maitland, Cape Town, 7405 Suite 259, Private Bag X19 Milnerton, 7435 Tel: +27 21 506 4901 E-mail: [email protected]

SIGNED:

TECHNICAL SIGNATORY:

Grant Ravenscroft

STATUS FINAL

Page 3 of 25


NOTICE This document is issued by SGS under its General Conditions of Service accessible at http://www.sgs.com/terms_and_conditions.htm. Attention is drawn to the limitation of liability, indemnification and jurisdiction issues defined therein. Any holder of this document is advised that information contained hereon reflects SGS’s findings at the time of its intervention only and within the limits of Client’s instructions, if any. SGS’s sole responsibility is to its Client and this document does not exonerate parties to a transaction from exercising all their rights and obligations under the transaction documents. Any unauthorised alteration, forgery or falsification of the content or appearance of this document is unlawful and offenders may be prosecuted to the fullest extent of the law. SGS Environmental Services is accredited by SANAS and conforms to the requirements of ISO/IEC 17025 for specific tests as indicated on the scope of accreditation to be found at http://sanas.co.za

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http://www.sgs.com/terms_and_conditions.htm

http://sanas.co.za/


TABLE OF CONTENTS

Description Page

1 INTRODUCTION 7

1.1 Scope of Work 7

1.2 Project Specific Description 7

2 GUIDELINES AND AIR QUALITY STANDARDS 9

3 METHODOLOGY 10

3.1 Ambient Air Quality 10

3.2 Data Capture 10

4 RESULTS 11

4.1 Ambient Air Quality Trends 11

4.2 Mean and Maximum Concentrations 12

4.3 Diurnal Trends 13

4.4 Wind and pollution roses 13

5 CONCLUSIONS AND RECOMMENDATIONS 14

Appendix 1 Summary Table of Hourly Means Appendix 2 Monitoring Methodologies Appendix 3 Recent changes in trace gas levels at Cape Point, South Africa

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ABBREVIATIONS

DEA National Department of Environmental Affairs DEADP Department of Environmental Affairs and Development Planning EPA See US EPA m3 Cubic Meters Max Maximum Min Minimum NEMAQA National Environment Management Air Quality Act NOX Nitrogen oxides PM-10 Particulate matter of aerodynamic diameter less than 10μm ppb Parts per billion SANS South African National Standard SO2 Sulphur dioxide μg/m3 Micrograms per cubic metre µm Micrometers US EPA United States Environmental Protection Agency WHO World Health Organisation

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1 INTRODUCTION

1.1 Scope of Work

This project covers the set-up and commissioning of four Air Quality Monitoring (AQM)

Stations in the Western Cape as well as continued maintenance, calibration and training

over a six-month period. The operations phase of the project commenced in April 2011.

1.2 Project Specific Description

This report evaluates data collected from the St Helena Bay monitoring station. After an

extensive site selection process, a suitable site was selected at the HP William Primary

School which is located to the north of the town and downwind from the local industries. This

site meets all the requirements as outlined in the US EPA’s “Quality Assurance Handbook

for Air Pollution Measurement Systems” and “SANS 1929” report.

Figure 1.2: Location of the air quality monitoring station at St Helena Bay

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Site preparation and training commenced during March 2011 with the station being set-up,

calibrated and tested on 28th March 2011. The meteorological equipment was commissioned

on the 4th May 2011 and the CO2 analyser installed on the 10th May 2011.

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2 GUIDELINES AND AIR QUALITY STANDARDS

There are no specific H2S and CO2 standards published for South Africa. However, the WHO

suggests a odour threshold of 7µg/m3 over a 30 minute period for H2S, as published in the

WHO Air Quality Guidelines for Europe (2nd edition) in 2000. However, odour thresholds of

between 1µg/m3 and 130µg/m3 have been proposed by various bodies worldwide as

concentrations at which different proportions of the population can detect the characteristic

odour.

CO2 concentrations show pronounced seasonal variations which are also affected by nearby

vegetation and combustion sources. However the background levels for CO2 are increasing

(please see Appendix 2 for more information).

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3 METHODOLOGY

3.1 Ambient Air Quality

Ambient concentrations of hydrogen sulphide (H2S) and carbon dioxide are measured at the

St Helena Bay monitoring site. Levels of these pollutants are presented graphically and in

table form in section 4 below.

3.2 Data Capture

Data is analysed for completeness against a required standards of 90% and presented in

table form below.

Table 3.2.1: Percentage data capture for hydrogen sulphide for April 2011.

Pollutant H2S CO2

% Capture 63% - *

* No data as the CO2 analyser was only installed in May 2011.

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4 RESULTS

4.1 Ambient Air Quality Trends

A graphical summary of pollutants for April 2011 is provided in Figures 4.1.1 and 4.1.2

below. A tabulated summary of results is attached as Appendix 1. No data is available for

CO2 as the analyser was only installed in May 2011.

Figure 4.1.1: Daily mean H2S concentrations

0

5

10

15

20

25

30

35

40

45

50

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

µg/m

3

Day

Daily Mean H2S ConcentrationsSt Helena Bay ‐ April 2011

Power problems on site

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Figure 4.1.2: Daily maximum 30-minute H2S concentrations

0

10

20

30

40

50

60

70

80

90

100

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

µg/m

3

Day

Daily Maximum 30‐min H2S ConcentrationsSt Helena Bay ‐ April 2011

WHO odour threshold 7µg/m3 (30‐min mean)

Power problems on site

4.2 Mean and Maximum Concentrations

Table 4.3.1: Mean & Maximum Concentrations

Pollutant Period H2S CO2

(µg/m3) ppm

Mean Month 1 -

Max. 1 hour 13 -

Max 24 hours 5 -

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4.3 Diurnal Trends

Diurnal trends of the ambient pollutants are only shown for those stations where overall data

capture was above 50%, which is considered representative enough for providing an

indication of diurnal trends.

Figure 4.3: Diurnal Trends for H2S

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

µg/m

3

Hour

Diurnal Trend for H2SSt Helena Bay ‐ April 2011

H2S

4.4 Wind and pollution roses

No wind rose is available for April 2011 as the meteorological station is not yet installed.

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5 CONCLUSIONS AND RECOMMENDATIONS

• This is the first reporting period for data from the St Helena Bay monitoring station

which was commissioned in April 2011.

• The average data collection for H2S at the St Helena Bay monitoring station was 63%

during April 2011 due to on site power problems between 22nd April and 2nd May

2011.

• The WHO odour threshold (7ug/m3 for 30-minute mean) was exceeded on seven

days during April 2011 (see Fig 4.1.2 for more details).

• The meteorological station was installed on 4th May 2011 and no data is available for

April 2011.

• Further analysis of data with regard to possible sources of pollution will be undertaken

when more data is available.

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Appendix 1

Summary Table of Hourly Means

1. H2S

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AMBIENT AIR QUALITY DATA FOR ST HELENA BAY - APRIL 2011

POLLUTANT : HYDROGEN SULPHIDE HOURLY MEAN CONCENTRATIONS - ug/m3

Start hour 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Mean MaxDay

1 - 11 - - - - - - 7 4 - - - - - - - - 4 6 7 5 9 9 - -2 6 - - - - - - - 5 3 - - - - 1 1 1 1 1 1 5 6 5 7 - -3 7 8 7 6 7 8 9 9 8 - - - - - - - - - - 2 4 4 5 7 - -4 7 8 8 8 - 7 9 8 8 1 0 2 0 0 0 - - - - 1 3 5 5 6 5 95 5 5 5 4 3 4 7 10 6 - - - - - - - - - - - - - - - - -6 - - - 1 2 4 4 5 2 1 - - 0 0 1 0 0 0 0 0 0 0 1 0 1 57 0 0 0 0 0 0 0 0 0 0 0 10 5 0 1 1 0 0 0 0 0 0 0 0 1 108 0 0 0 0 0 0 1 1 1 3 5 5 0 0 0 0 0 0 0 0 1 0 0 1 1 59 2 0 0 2 1 1 1 1 1 1 2 1 1 0 0 0 0 0 0 0 0 0 0 0 1 2

10 3 2 3 0 3 1 4 2 4 1 3 1 1 0 0 0 0 0 0 0 6 5 3 1 2 611 0 0 5 3 4 5 3 4 1 0 0 1 1 1 2 0 0 0 0 0 0 0 1 3 1 512 2 3 4 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 413 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 114 0 0 0 0 1 0 0 0 0 1 1 6 1 1 0 0 0 0 0 0 0 0 0 0 0 615 0 0 0 0 0 0 0 0 1 4 13 11 0 0 0 0 0 0 0 0 0 0 0 0 1 1316 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 0 0 0 0 0 0 0 0 117 0 0 0 0 0 0 0 0 1 10 4 1 0 0 0 0 0 0 0 0 0 0 0 0 1 1018 - 0 0 3 1 0 0 1 5 2 1 0 0 0 0 0 0 0 0 0 0 1 8 0 1 819 0 2 0 0 1 0 1 1 3 5 3 2 0 0 0 0 0 0 0 0 0 0 0 0 1 520 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 121 0 0 0 - - - - - - - - 5 1 0 0 0 0 0 0 0 0 0 0 0 0 522 0 0 0 0 0 0 0 0 0 0 2 0 0 1 0 0 0 0 - - - - - - 0 223 - - - - - - - - - - - - - - - - - - - - - - - - - -24 - - - - - - - - - - - - - - - - - - - - - - - - - -25 - - - - - - - - - - - - - - - - - - - - - - - - - -26 - - - - - - - - - - - - - - - - - - - - - - - - - -27 - - - - - - - - - - - - - - - - - - - - - - - - - -28 - - - - - - - - - - - - - - - - - - - - - - - - - -29 - - - - - - - - - - - - - - - - - - - - - - - - - -30 - - - - - - - - - - - - - - - - - - - - - - - - - -

Mean 2 2 2 1 1 2 2 2 3 2 2 3 1 0 0 0 0 0 0 1 1 1 2 2 1Maximum 7 11 8 8 7 8 9 10 8 10 13 11 5 1 2 1 1 1 4 6 7 6 9 9 5 13

Department of Environmental Affairs and Development Planning

AQ205 Monthly Ambient Air Quality Report for St Helena Bay

Page 16 of 25


Appendix 2

Monitoring Methodologies

1. Continuous Real Time Monitors

Continuous real-time monitors are used to measure real-time concentrations of gases.

These are usually one part of an AQMS and often are remote in location and need to be

connected in a network as per Figure A below. Such a system would have the following as a

minimum requirement:

• Environmental enclosure

• Inlet manifold

• Analysers

• Calibration

• Meteorological instrumentation

• Data acquisition

• Data reporting

• Communication

• Housekeeping (log book, shelter check sheet, instruments data sheets)

In particular the monitoring station would have the following basic components:

• Monitoring station design

– Housing

– Air inlet system

– Monitoring instrumentation

– Calibration of monitors

– Logging devices

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Figure A: eThekwini Municipality Multi Point Plan AQMS

Monitoring Methods

This section gives an overview of the methods employed in the continuous monitoring of

ambient compounds.

CO/CO2: aremonitored continuously by non-dispersive infrared photometry

• The non-dispersive infrared photometry process is based upon the absorption of infrared

light by CO or CO2

NOX are measured continuously by the principle of chemiluminescence

Page 18 of 25


• The air sample is split into two pathways; one to measure NO, and the other to measure

total NOX

• The intensity of light is measured with a photomultiplier to obtain the concentration of NO

• To obtain NO2 the sample gas is passed through a molly converter

• Measurement is the sum of NO2 and NO, expressed as NOX

SO2/H2S are monitored continuously by pulsed fluorescence.

• In this method, air is drawn through a sample chamber where it is irradiated with pulses

of ultra-violet light.

• Any SO2 in the sample is excited to a higher energy level and upon returning to its

original state, light or fluorescence is released.

• The amount of fluorescence measured is proportional to the SO2 concentration.

O3 is monitored continuously using ultra-violet (UV) light absorption

• The sampled air is exposed to UV light, which is absorbed by O3.

• The amount of UV light absorbed is proportional to the amount of O3 in the sample; that

is, the more UV light is absorbed, the greater the amount of O3 in the sample.

PM-10 is monitored continuously and intermittently

• The Tapered Element Oscillating Microbalance (TEOM) is the most widely used

continuous PM-10 monitor

• The TEOM draws an air sample through an inlet stream that aerodynamically separates

particles of a specified diameter

• The air sample then passes through a filter that is attached to a tapered element in the

mass transducer.

• This tapered element vibrates at its natural frequency.

• As particles are deposited onto the filter the oscillating frequency changes in proportion to

the amount of mass deposited.

Meteorological parameters such as wind direction, wind speed, temperature, relative

humidity, solar radiation and atmospheric pressure are monitored in order to assist in

identifying the sources of elevated concentration events or episodes

Page 19 of 25


2. Quality Control Requirements

Quality control of the monitored data is important to verify that the data reported is accurate

and of a low uncertainty. Each monitoring station or passive monitoring site should be

treated as if it were a laboratory. A laboratory is defined as “A place equipped for testing and

analysis” or “A place providing the opportunity for observation in a field of study”. It must be

noted that it has been stated by DEA that only air quality data that is accredited will be

accepted by DEA. The definition for accreditation is “the procedure by which an authoritative

body gives formal recognition that a body is competent to carry out specific tasks”. In order

to be accredited a sampling method must have:

• A recognised methodology that competence can be measured against

• A quality system

• Have been audited by a certification body

A relevant quality system for air quality measurements according to SANAS is ISO 17025.

This system provides guidance to laboratories on essential elements for both:

• Quality management

• Technical requirements for the proper operation of a testing laboratory

3. Instrument Calibration and Frequency

This section covers the calibration of continuous air quality monitors. The basic requirements

based on the US EPA Red Book are:

• Each analyser must have a dynamic calibration every three months

• Note: This type of calibration must also be carried out on installation, after any repair, if

tolerances of zero/ span are not met and if the analyser is relocated

• Zero and span calibration every two weeks

• Zero check every other week

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4. Data Acquisition Requirements

This section also refers to an AQMS based on continuous monitoring from a monitoring

station and to the data logging system:

The data logger must:

• Be verified annually

• Output from the analysers must be recorded

• Generate hourly mean concentrations

• Be able to scan at 30 second intervals with a minimum scan period of 1 hour and store

this data

• Collect at least 40 minutes of uninterrupted data per hour for a valid average

• Use calculations verified by a statistician

5. Site Selection

The following quote is noteworthy when considering the location of sites: “Irrespective of how

well a monitoring station is run, if it is not sited correctly data collected will have little value”

As was mentioned earlier sites are selected for one of the following reasons:

• To judge compliance with air quality standards

• To activate emergency control procedures for episodes

• To observe pollution trends throughout a region

• To provide a database for research.

When selecting monitoring sites the following must be considered:

• Economic – Resources must be available for the expensive instrumentation, data

retrieval and evaluation, maintenance and quality assurance and reporting of data

• Security – Problems can arise in this regard that make a site unsuitable when standard

measures are taken into account

• Logistics – Planning, staffing, procurement procedures, training, communications, safety,

task scheduling

• Atmospheric conditions

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o Variability of air pollutants and their transport (effects of buildings, terrain and heat

sources)

o Dispersion factors – wind speed, wind direction, atmospheric stability

• Topography – Transport and diffusion of air pollutants are complicated by topographical

features such as valleys or hills

• Pollutant consideration: A sampling site for one pollutant may or may not be suitable for

other pollutants

o For example, monitoring ozone close to primary NO emissions would not provide

accurate pollutant information

• The final placement once a monitoring site has been selected depends on the presence

of physical obstructions, accessibility and availability of utilities.

• Obstructions such as trees and buildings significantly affect the air flow over the

monitoring station and the placement should expose the station to the general air flow of

the area to prevent sampling bias.

• Major roads can produce bias and sites should be 15-60m away unless there are specific

requirements for roadway monitoring. Typically sites would be between 3m and 15m

away in this case.

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6. Data Management

All monitoring stations produce data that may be used for various reasons as outlined above.

The following should be noted when dealing with this monitoring data and systems should be

designed to accommodate the following:

• A copy of the raw data must always be available

• A record must be kept of any adjustments made

• All multiplication factors/ algorithms/ manipulations on the data must be recorded and

reported

• Data must be kept for a minimum of 3 years

• When data is reported the temperature and pressure at which the analyser was last

calibrated must be indicated on the test report

The following points must be considered when preparing a monitoring plan:

• Local authority responsible for monitoring

• Check to see if Province has information about your area

• Check to see whether DEA has information about your area (SAAQIS)

• Do screening study to see which pollutants if any are of concern

• SANS 1929 lets you make management decisions on whether costly continuous

monitoring is needed

• If so focus on quality control, reporting 80% or more of available data

• Use data to mange improvements in air quality

Page 23 of 25


Appendix 3

Recent changes in trace gas levels at

Cape Point, South Africa

Page 24 of 25

RECENT CHANGES IN TRACE GAS LEVELSAT CAPE POINT, SOUTH AFRICA

E-G. Brunke1, C. Labuschagne1 and H.E. Scheel21 South African Weather Service, PO Box 320, Stellenbosch, South Africa. [email protected]

2 Forschungszentrum Karlsruhe, IMK-IFU, Garmisch, Germany.

1978 1982 1986 1990 1994 1998 2002 200620

30

40

50

60

70

80

90

Monthly means, regression curve and trend

Cape Point: CO (1979-2006)

CO

[ppb

]

YEAR

1995 1997 1999 2001 2003 2005 2007305

310

315

320

325

N2O Linear Fit

Cape Point: N2O (1996-2006)

N2O

[ppb

]

YEAR

Average increase: 0.72 ppb/yr

1992 1994 1996 1998 2000 2002 2004 2006350

355

360

365

370

375

380

385

Trend Monthly means Regression curve

Cape Point: CO2 (1993-2006)

CO

2 [ppm

]

YEAR

1992 1994 1996 1998 2000 2002 2004 20061.0

1.5

2.0

2.5

3.0

Smoothed rates Linear fit

Cape Point: CO2 growth rates (1993-2006)

CO

2 gro

wth

rate

[ppm

/yr]

YEAR

Measurements of CO2, CH4, N2O, CO and O3 have been made at Cape Point (CPT, 34 °S, 18 °E) spanning differing time periods, ranging from 14 complete years for CO2 to 28 years in the case of CO. With respect to N2O, the first seven years (1989 –1995) have been excluded from current analyses because of lower data quality.

The poster presents the latest trend and growth rate estimates, based on data filtered with respect to background concentrations. Note that the temporal variability of trend curves and growth rates is dependent on the degree of smoothing chosen for the calculations.

The CO2 growth rates, calculated as derivatives of the trend curve, have fluctuated between 1.5 and 2.2 ppm yr-1 (as obtained with 5-year smoothing). Linear re-gression performed on the growth rates indicates an increase of the fit from 1.6 ppmyr-1 in early 1993 to 2.1 ppm yr-1 at the end of 2006.

For CH4, an overall decrease in growth-rates, fluctuating markedly over the years, has been observed since 1983. Methane levels have stabilized since 2003, and during 2006 the CH4 growth rate even dropped to about -1 ppb yr-1. A linear fit of the growth rates yields values of 13 ppb yr-1 for the beginning of 1983 and zero growth for mid-2005.

From 1982 till the mid-1990s the non-background CH4 trend has closely matched that of the background data. However, thereafter non-background levels have continued their upward trend till present. This is probably related to growing local sources to the north of the station. See plots below.

The CO time series does not display a significant long-term trend, whereas inter-annual variability is evident. However, since 2003 an overall decline of the CO mole fractions has been observed. This culminated in an abnormally low annual minimum during February 2006 and a lower than usual annual maximum in October 2006.

For surface ozone, a positive trend was recorded between 1990 and 2002, accom-panied by an increase in seasonal peak-to-peak amplitudes. Since 2003 the increase has levelled off again.

Acknowledgements: We are indebted to our colleagues D. van der Spuy for processing the raw data and to B. Parker for his IT support. September 2007

Wind sector-dependent growth rates reveal an enhanced long-term increase of CO2 and CH4 for the northerly sector. For CO2, the ppm-per-year increase was 3.2 % higher than for background conditions (1.94 vs. 1.88 ppm yr -1). Similar calculations for CH4 yielded a 55 % higher rate relative to background (3.74 vs. 2.41 ppb y -1). Due to the underlying CH4 concentration distribution, the medians yielded a smaller difference between the rates. The increased trends reflect the recent expansion of the greater Cape Town area.

1982 1986 1990 1994 1998 2002 2006-4

0

4

8

12

16

Smoothed rates Linear fit

Cape Point: CH4 growth rates (1983-2006)

CH

4 [p

pb]

YEAR

1982 1986 1990 1994 1998 2002 20061550

1600

1650

1700

1750

1800

Trend (background)

Monthly means (background) withregression curve

Trend of non-backgroundCape Point: CH

4 (1983-2006)

CH

4 [p

pb]

YEAR

1. 6 5

1. 7 0

1. 7 5

1. 8 0

1. 8 5

1. 9 0

1. 9 5

2 . 0 0

0°

20°

40°

60°

80°

100°

120°

140°

160°

180°

200°

220°

240°

260°

280°

300°

320°

340°

Av gs [ ppm]

M e d i a ns [ ppm]

CO2

1. 6 5

1. 7 0

1. 7 5

1. 8 0

1. 8 5

1. 9 0

1. 9 5

2 . 0 0

0°

20°

40°

60°

80°

100°

120°

140°

160°

180°

200°

220°

240°

260°

280°

300°

320°

340°

Av gs [ ppm]

M e d i a ns [ ppm]

CO2

0 . 0

1. 0

2 . 0

3 . 0

4 . 00°

20°

40°

60°

80°

100°

120°

140°

160°

180°

200°

220°

240°

260°

280°

300°

320°

340°

A vgs [ ppb]

M edians [ ppb]

CH4

0 . 0

1. 0

2 . 0

3 . 0

4 . 00°

20°

40°

60°

80°

100°

120°

140°

160°

180°

200°

220°

240°

260°

280°

300°

320°

340°

A vgs [ ppb]

M edians [ ppb]

CH4

For N2O a nearly linear growth of 0.7 ppb yr-1 has been determined from the observations between 1996 and 2006.

Location of the station at the southern tip of the Cape Point nature reserve. Trends of CO2 and CH4have been determined as a function of wind direction for the period 1999 – 2005.

1982 1986 1990 1994 1998 2002 20060

10

20

30

40

Cape Point: Surface Ozone (1983-2006)

O3 [

ppb]

YEAR

Monthly means,regression curve andtrend

CO2 growth rates in ppm yr -1

CH4 growth rates in ppb yr -1

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