Acid Rain Links to Methane Emissions from Wetlands Vincent Gauci - PowerPoint PPT Presentation

Acid Rain Links to Methane Emissions from Wetlands Vincent Gauci

The Global Methane Budget Biomass Burning Termites 10% 7% Coal 7% Rice paddies Natural Gas 20% 8% Landfill 7% Enteric Freshwater Fermentation 1% 15% Natural Oceans Wetlands 2% Hydrates 22% 1%

Atmospheric Methane Growth Rate Dlugokencky et al 1998

land air to sea air land air to sea air 10+ 17 70 + 2.5 3 11 sea air to land air sea air to land air 15-30 wet and dry deposition 2 6 + 53 22-37+ 17 volatile sulfur from volatile sulfur from waterlogged soil waterlogged soil volatile biogenic volatile biogenic sulfur e.g.. DMS 40 sulfur e.g.. DMS weathering weathering 4 sea-spray sea-spray River River 5 runoff runoff 47 + 53 anthropogenic volcanic anthropogenic volcanic 33 + 53 emission emission emission emission LAND OCEAN magma 7 The Sulfur Cycle(values in Tg-S/year) (modified from Graedel and Crutzen 1993)

Distribution of Wetland Ecosystems FORESTED BOG NONFORESTED BOG ALLUVIAL FORESTED SWAMP NONFORESTED SWAMP E. Mathews and I. Fung (1987)

Modelled total S-dep 1960 1960-2030 Global interpolated distribution of total (wet + dry) S- deposition (mg/m 2 /year) for the 1990 years 1960 (a), 1990 (b) and 2030 (C) 2030

How does the addition of sulfate affect the rate of methane emission • Microbially mediated processes. • Two anaerobic microbial communities (sulfate reducers and methane producers) are in direct competition over limiting substrates

Microbial Competition Sulfate absent Sulfate present M SRB M SRB substrate substrate Acetate H 2 + CO 2 Acetate H 2 + CO 2 CH 4 + CO 2 CH 4 CO 2 + H 2 S

Previous work investigating the link between sulphate and methane emission • Single, large fertilisation doses (10 3 kg/ha) rice paddies. • Lab peat cores in controlled environments (single ‘pollution’ doses of around 50kg/ha) • Continuous pollution level doses - (limited data)

Methods CH 4 CH • Field location 4 • Experimental design • Static Chamber method

Field Location Moidach More x ITE Edinburgh x

Moidach More Inset N Study Site

Chamber Design Sample syringe Suba-seal 6mm acrylic Neoprene ‘O’ ring Polypropylene pipe (300mm ID)

Relationship between the number of sedge shoots and methane flux 50 40 Flux /mgCH 4 /m 2 /day 30 20 10 R 2 = 0.4775 0 0 20 40 60 80 100 120 140 Sedge shoot number

Experimental Design BLOCK 3 KEY TREATMENT Controls 25 Kg SO 4 -S 50 Kg SO 4 -S 100 Kg SO 4 -S 50 Kg SO 4 -S BLOCK 1 BLOCK 2 (single)

Relationship between the number of sedge shoots and pre-treatment methane flux 50 40 Flux /mgCH 4 /m 2 /day 30 20 10 R 2 = 0.4775 0 0 20 40 60 80 100 120 140 Sedge shoot number

Control vs. 25kg SO 4 -S/ha/yr 250 control 25kg 200 µ gCH 4 /plant/day 150 100 50 0 11/03/97 19/06/97 27/09/97 05/01/98 15/04/98 24/07/98 01/11/98 09/02/99 date

Control vs. 50kg SO 4 -S/ha/yr 200 control 50kg 150 µ gCH 4 /plant/day 100 50 0 11/03/97 19/06/97 27/09/97 05/01/98 15/04/98 24/07/98 01/11/98 09/02/99 date

Control vs. 100kg SO 4 -S/ha/yr 200 control 100kg 150 µ gCH 4 /plant/day 100 50 0 11/03/97 19/06/97 27/09/97 05/01/98 15/04/98 24/07/98 01/11/98 09/02/99 date

Cumulative mean daily methane flux from Moidach More 30 1997 1998 25 Control 24.5g 20 50kg 19.0g (-22%) 25kg 17.4g (-29%) g CH 4 m -2 100kg 16.6g (-32%) 15 10 5 0 M A M J J A S O N D J F M A M J J A S O N D J

P-value (Control vs. Treatment )TREATMENTMean CH 4 Flux ( ± s.e.)(mg CH 4 .m -2 .day -1 ) (a)(b) Pre-tre

Total monthly rainfall /mm 160 a) 140 120 100 80 60 40 20 0 Temperature 10cm below water-table b) 15 10 5 0 0 Water-table /cm -5 from surface -10 -15 -20 c) -25 A M J J A S O N D J F M A M J J A S O N 1997 1998 Total monthly rainfall (a), peat temperature 10 cm below water table (b) and mean water-table position (c) over the course of the experiment.

% variation in (treatment) methane flux and mean water table in 1997 -1998 20 5 3 per. Mov. Avg. (mean CH4 variation) 3 per. Mov. Avg. (water table) 10 Mean % variation in treatment flux 0 0 mean water table/ cm -10 -5 -20 -10 -30 -40 -15 -50 -20 -60 -70 -25 30/05/97 07/09/97 16/12/97 26/03/98 04/07/98 12/10/98 20/01/99 Date

PVCH 4 = 2.2*temp - 44.7*WT -1 -71.7 R 2 = 0.67 P<0.0001 0 -10 -20 -30 -40 vs. control flux -50 16 14 12 -60 % difference in treatment flux 10 8 -70 depth from peat surface 6 -2 -4 4 to water table (cm) Water table -6 2 -8 0 temp (deg C) 10cm below -10 Measured data ( • ) and modelled data surface showing the relationship between treatment effect, temperature and water table (specific to Moidach More where water-table varied temporally). Heavy lines excludes areas for which no data is available.

Porewater Chemistry Porewater [CH 4 ], µ M Porewater [SO 4 -S], µ M 0 50 100 0 20 40 60 Depth below peat surface /cm a) b) 10 ** * 20 * 30 control 50 Kg SO4-S ** P< 0.01 * P < 0.05

What are the implications e the implications f for global or global What ar atmospheric pheric methane in the methane in the future? future? atmos Method: Method: •Tropospheric • Tropospheric S simulation in GISS GCM S simulation in GISS GCM •CH • CH 4 4 from natural wetlands in GISS GCM from natural wetlands in GISS GCM • •Estimat Estimation of rice CH ion of rice CH 4 4 using IPCC method using IPCC methodologies ologies

Modelled global S - deposition i 1960 ii 1990 iii 2030 Global interpolated distribution of total (wet + dry) S-deposition (mg/m 2 /year) for the years 1960 (a), 1990 (b) and 2030 (C) and areas impacted with S in excess of the 15kg/ha/year threshold for the same years (i,ii,iii respectively).

Natural wetlands CH 4 emissions 1960-2030

Modelled Northern Wetland CH 4 Emissions As Affected by S deposition (annual CH 4 emissions /Tg) Nothern Wetland (>50 CH 4 flux with S -deposition % flux deg N th ) CH 4 flux/Tg (Tg) reduction 1960 33.9 29.2 13.9 1990 39.3 32.4 17.3 2030 46.2 39.1 15.4

Estimated Rice Paddy Methane emissions annual CH4 emissions from rice /Tg 90 86.2 Changes in rice production only 80 70.6 70 63.6 56.4 59.8 60 Changes in rice 56.4 production + S-dep 50 40 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 year