Whole ecosystem approach to understanding reservoirs, and the resulting policy impacts

Transcription

1 Whole ecosystem approach to understanding reservoirs, and the resulting policy impacts Britt Hall and Vincent St.Louis Experimental Lakes Area Reservoir Project Flooded Uplands Dynamics Experiment Collaborative team: John Rudd, Carol Kelly, Drew Bodaly, Sherry Schiff, Ken Beaty, Nigel Roulet, Grant Edwards, Cory Matthews, Elizabeth Joyce, Jason Venkiteswaran, Nathalie Boudreau, Kris Rolfus, Jim Hurley, Reed Harris

2 What got it all started! Wetland ponds in the Hudson Bay Lowlands were sources of the greenhouse gases CO 2 and CH 4 to the atmosphere. If you flooded landscapes to create reservoirs for hydroelectricity production, would they also be were sources of CO 2 and CH 4 to the atmosphere.

3 This is a big question because in the era of adapting to climate change, hydroelectricity was being touted as carbon-free source of energy.

4 Mercury in northern pike in Hydro Quebec reservoirs Another issue is the production and bioaccumulation of MeHg in reservoirs following flooding. This creates long-term socioeconomic problems for Indigenous peoples and others that rely on healthy freshwater resources and services for their ways of life.

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6 Flooding landscapes changes how they naturally function ALIVE AND PRODUCTIVE

7 Flooding landscapes changes how they naturally function DEAD AND DECAYING

8 Using unique whole-ecosystem experimentation at the Experimental Lakes Area, we were able to ask: What is the net impact of flooding landscapes on greenhouse gas (CO 2 and CH 4 ) emissions and methylmercury production? Does flooding different amounts of organic carbon change the intensity of these impacts? How long do these impacts last post-flooding? Are hydroelectric reservoirs important net sources of greenhouse gases to the atmosphere?

9 What is the fate of mercury and carbon when reservoirs are created?

10 Experimental Whole-ecosystem Reservoirs ecosystem at the manipulations ELA Scientists at ELA use mass balance budgets on impacted and natural lakes to determine the fate of matter in lakes Year 5 Prior to flooding

11 Experimental What Reservoirs you need to at create the ELA a mass budget Our currency was Mercury (Hg) and Carbon

12 Mercury transformations in the environment Microbial methylation in wetlands and anoxic sediments is the main source of MeHg in aquatic environments Many environmental factors affect MeHg production Because bacteria produce MeHg, our hypothesis was that increased carbon in reservoirs would fuel MeHg production

13 Experimental Reservoirs at the ELA What you need to create a mass budget Our currency is Mercury (Hg) Our scale is whole ecosystem and before/after Experimental Lakes Area Reservoir Project

14 Experimental Reservoirs at the ELA Building the dam at the wetland outflow

15 Experimental Floating Floating Reservoirs of the peat peat in at the the ELA in the flooded years wetland post-flood Preflood (1992) First year of flooding (1993) Five years postflood (1997) Nine years postflood (2001)

16 Experimental Reservoirs at the ELA Carbon stores in experimental reservoirs Vegetation Fulvic/humic soil and litter Mineral soil Peat Carbon storage kg C ha High C Medium C Low C Wetland High C Medium C Low C Peatland

17 Flooding upland forests FLooded Uplands Dynamics EXperiment

18 Upland reservoirs High Carbon Site Preflood Postflood Low and Medium Carbon Sites

19 Experimental Reservoirs at the ELA What you need to create a mass budget Our currency is Mercury (Hg) Our scale is whole ecosystem and before/after Our transactions are how MeHg moves and changes

20 Building the reservoirs Components of a MeHg budget LOSS Evasion 0 Hg INPUT Gauged inflow pipe INPUT Precipitation (Open areas) INPUT Throughfall (Forested areas) INPUT Litterfall (INPUT from Roddy Lake) INPUT Direct run- Wooden dike (>1m depth) LOSS Gauged outflow weir LOSS Outflow pipe (at drawdown) LOSS Seepage Gravel dike (<1m depth) 07 Jan

21 Building the reservoirs Components of a MeHg budget LOSS Evasion 0 Hg INPUT Gauged inflow pipe INPUT Precipitation (Open areas) INPUT Throughfall (Forested areas) INPUT Litterfall (INPUT from Roddy Lake) INPUT Direct run- Wooden dike (>1m depth) LOSS Gauged outflow weir LOSS Outflow pipe (at drawdown) LOSS Seepage Gravel dike (<1m depth) 07 Jan

22 Building the reservoirs Components of a MeHg budget LOSS Evasion 0 Hg INPUT Gauged inflow pipe INPUT Precipitation (Open areas) INPUT Throughfall (Forested areas) INPUT Litterfall (INPUT from Roddy Lake) INPUT Direct run- Wooden dike (>1m depth) LOSS Gauged outflow weir LOSS Outflow pipe (at drawdown) LOSS Seepage Gravel dike (<1m depth) 07 Jan

23 Building the reservoirs Components of a MeHg budget LOSS Evasion 0 Hg INPUT Gauged inflow pipe INPUT Precipitation (Open areas) INPUT Throughfall (Forested areas) INPUT Litterfall (INPUT from Roddy Lake) INPUT Direct run- Wooden dike (>1m depth) LOSS Gauged outflow weir LOSS Outflow pipe (at drawdown) LOSS Seepage Gravel dike (<1m depth) 07 Jan

24 MeHg storage (mg/ha) Total MeHgTotal in FLUDEX MeHg in reservoirs FLUDEX reservoirs Low C 4000 Low C reservoir MeHg storage mg ha Total storage prior to flooding Food web Net export over weirs Organic soils Mineral soils Preflood Year 1 Year 2 Year 3

25 MeHg storage (mg/ha) Total MeHgTotal in FLUDEX MeHg in reservoirs FLUDEX reservoirs Medium C 4000 Medium C reservoir MeHg storage mg ha Total storage prior to flooding Food web Net export over weirs Organic soils Mineral soils Preflood Year 1 Year 2 Year 3

26 MeHg storage (mg/ha) Total MeHgTotal in FLUDEX MeHg in reservoirs FLUDEX reservoirs High C MeHg storage mg ha Medium High C C reservoir Total storage prior to flooding Food web Net export over weirs Organic soils Mineral soils Total MeHg storage in peat in the wetland reservoir in year 2 = 6000 mg/ha Preflood Year 1 Year 2 Year 3

27 . Minimizing carbon flooded minimized production of MeHg in reservoirs

28 MeHg storage (mg/ha) Total MeHgTotal in FLUDEX MeHg in reservoirs FLUDEX reservoirs High C MeHg storage mg ha Medium High C C reservoir Total storage prior to flooding Food web Net export over weirs Organic soils Mineral soils Total MeHg storage in peat in the wetland reservoir in year 2 = 6000 mg/ha Preflood Year 1 Year 2 Year 3

29 Total MeHg in FLUDEX reservoirs Medium C MeHg yield over five years Year 1 MeHg yeild (mg/ha) Year High C Medium C Low C

30 Results from ELARP MeHg concentration ng L -1 MeHg concentration (ng/l) Before flooding After flooding Flooding areas with large organic carbon stores results in a worst case scenario for long term MeHg contamination

31 . Minimizing carbon flooded minimized the duration of MeHg production in reservoirs

32 Muskrat falls stuff??

33 Experimental Reservoirs at the ELA Not just mass budgets

34 Concentrations of CO 2 and CH 4 in the reservoir water Experimental Lakes Area Reservoir Project Flooded Uplands Dynamics Experiment Flooded Concentration (µmol L -1 ) Concentration (µmol L -1 ) High C reservoir 8 Intermediate C reservoir Low C reservoir Weeks post-flood, 1999 Weeks post-flood, Weeks post-flood, 2001 Year 1 post-flood Year 2 post-flood Year 3 post-flood

35 Average reservoir surface fluxes of CO 2 and CH 4 in first 2-3 years post-flood

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37 Updated estimates of CO 2 and CH 4 emissions from global hydroelectric reservoirs

38 Greenhouse gas emissions from reservoirs continues to be a hot topic of research!

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40 CONCLUSIONS Using unique whole-ecosystem experimentation at the Experimental Lakes Area, we were able to conclude: Flooding landscapes increases net greenhouse gas (CO 2 and CH 4 ) emissions and methylmercury production Flooding less amounts of organic carbon lessens the intensity of these impacts The duration of these impacts post-flooding depends on the amount of organic carbon flooded Hydroelectric reservoirs are net sources of greenhouse gases to the atmosphere

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