WINTER UNDER-ICE PATTERNS OF GREENHOUSE GASES IN LAKES OF INTERIOR ALASKA
Arctic lake greenhouse gas emissions (GHG) are poorly defined, in part due to limited sampling access and restricted sampling during winter and shoulder seasons. To better understand patterns and drivers of winter under-ice GHG buildup and potential for emissions at spring thaw, we surveyed CO2 and CH4 concentrations and isotopic composition in late winter in thirteen remote interior Alaskan lakes. Gas partial pressures ranged widely and were positively correlated to each other (~400 to 18000 ppm (CO2), ~2 to 30000ppm (CH4)). Across the region, shallow, low elevation lakes were sites of greatest under-ice concentrations of both gases. These sites also had the greatest content of dissolved organic carbon to fuel GHG production. Elevated CH4 content was restricted to lakes with hypoxic conditions, while elevated CO2 was observed in both oxic and hypoxic conditions, inversely proportional to oxygen content. Stable isotope values of CH4 ranged widely, over 50 permil, indicating the net importance of CH4 oxidation may vary greatly among the lakes. This survey provides key information to help explain the spatial patterns and factors related to winter greenhouse gas buildup in lakes, currently a major unknown in many arctic regions.
David Butman (Co-Presenter/Co-Author), University of Washington, firstname.lastname@example.org;
Matthew Bogard (Co-Presenter/Co-Author), University of Washington, email@example.com;
Mark Dornblaser (Co-Presenter/Co-Author), USGS, firstname.lastname@example.org;
Robert Striegl (Co-Presenter/Co-Author), USGS, email@example.com;
Catherine Kuhn (Co-Presenter/Co-Author), University of Washington, firstname.lastname@example.org;
Madeline O'Dwyer (Primary Presenter/Author), University of Washington, email@example.com;