Carbon dioxide supersaturation in peatland waters and its contribution to atmospheric efflux from downstream boreal lakes

• Published in: Journal of Geophysical Research: Biogeosciences Vol. 115; no. G4
• Main Authors: Whitfield, C. J., Seabert, T. A., Aherne, J., Watmough, S. A.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.12.2010; American Geophysical Union
• Subjects: Alberta; Alkalinity; Atmosphere; Biogeochemistry; Carbon; Carbon dioxide; dissolved organic carbon; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geobiology; hydrology; Lakes; peatlands; Supersaturation; Surface water; Water chemistry; Wetlands; Alberta; Canada; Western Canada; atmosphere; carbon dioxide; basicity; mass balance; ground water; Supersaturation; concentration; loading; North America; alkalinity; greenhouse gas; Dissolved organic carbon; surface water; drainage basins; aquifers; partial pressure; pH; Boreal; lakes; residence time
• ISSN: 0148-0227; 2169-8953; 2156-2202; 2169-8961
• DOI: 10.1029/2010JG001364

Carbon fluxes at two boreal peatland‐dominated catchments in northeastern Alberta were investigated through the analysis of fen and lake water chemistry and the measurement of partial pressure of carbon dioxide (pCO2) using headspace gas analysis. All waters had low pH (<5.3) and Gran alkalinity (<2.3 mg L−1), high DOC (>15 mg L−1), and were supersaturated with carbon dioxide (CO2) with respect to the atmosphere (CO2: 1.2–54 times atmospheric). Nonetheless, CO2 concentrations in the study lakes were significantly lower compared with surface water pools in associated fen systems. Average atmospheric flux of CO2 from the two lakes were 0.18 and 0.48 g C m−2 d−1, while potential fluxes from small surficial pools on the fen complexes were an order of magnitude higher. The higher average efflux estimated at one of the lakes (relative to the other) was attributed to shorter lake residence time and smaller relative lake area (i.e., higher relative carbon loading). Carbon mass balances for the lakes suggest that they act as conduits for dissolved CO2 from surrounding fen complexes to the atmosphere. In one of the two study catchments (with negligible groundwater sources), inputs of dissolved CO2 from fen surface waters supported a substantial component (∼30%) of the lake atmospheric CO2 efflux.