Greenhouse Gas Emissions from Boreal Reservoirs in Manitoba and Quebec, Canada, Measured with Automated Systems

Growing concern over the contribution of freshwater reservoirs to increases in atmospheric greenhouse gas (GHG) concentrations and the relevance of long-term continuous measurements has led Fisheries and Oceans Canada, in conjunction with Manitoba Hydro,to develop continuous GHG monitors. Continuous water pCO(2), pCH(4), and pO(2) measurements were gathered to estimate gas fluxes in one temperate reservoir (Riviere-des-Prairies) and two boreal reservoirs (Eastmain-1 and Robert-Bourassa) in Quebec, and in four boreal reservoirs (Grand Rapids, Jenpeg, Kettle, and McArthur Falls) in Manitoba, Canada. Mean daily CO2 fluxes ranged between 7 and 14 mmolCO(2) . m(-2) . d(-1) in Manitoba and between 15 and 55 mmolCO(2) . m(-2) . d(-1) in Quebec. Summertime episodes of water undersaturation in CO2 were observed at Jenpeg, Kettle, and McArthur, suggesting higher productivities of these systems compared to the other systems studied. Mean daily CH4 fluxes ranged between 0 and 69 mu molCH(4) . m(-2) . d(-1) in Manitoba and between 9 and 48 mu molCH(4) . m(-2) . d(-1) in Quebec. Comparisons of results obtained in the Eastmain-1 area using automated monitors, floating chambers or dissolved gas analyses over multiple-station field campaigns demonstrated that a continuous GHG monitor at a single sampling station provided representative and robust results.