Chapter

Greenhouse Gas Emissions — Fluxes and Processes

Part of the series Environmental Science pp 209-232

GHG Emissions from Boreal Reservoirs and Natural Aquatic Ecosystems

  • Alain Tremblay
  • , Jean Therrien
  • , Bill Hamlin
  • , Eva Wichmann
  • , Lawrence J. LeDrew

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Abstract

Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) gross fluxes were measured at the air-water interface of 205 aquatic ecosystems in the Canadian boreal region from 1993 to 2003. Fluxes were obtained with a floating chamber connected to an automated NDIR or a FTIR instrument. The results show a temporary increase in CO2 and CH4 fluxes, followed by a gradual return to values comparable to those observed in natural aquatic ecosystems (lakes, rivers and estuaries). Mean values for CO2 and CH4 measured in Québec's reservoirs older than 10 years were 1508±1771 mg CO2·m−2·d−1 and 8.8±12 mg CH4·m−2·d−1. Our results showed a strong similarity between lakes, rivers, and old reservoirs across a 5000 km transect from the west coast to the east cost of Canada. These values are comparable to those observed in Finland or in the sub-tropical semi-arid western USA. Although several limnological parameters can influence these fluxes, none showed a statistical relationship. However, levels of CO2 or CH4 fluxes are influenced by pH, wind speed, depth at sampling stations and latitude.