Carbon dioxide and methane fluxes in the littoral zones of two lakes, east Antarctica

During the summertime of 2007/2008, carbon dioxide (CO2) and methane (CH4) fluxes across air–water interface were investigated in the littoral zones of Lake Mochou and Lake Tuanjie, east Antarctica, using a static chamber technique. The mean fluxes of CO2 and CH4 were −70.8 mgCO2 m−2 h−1 and 144.6 μgCH4 m−2 h−1, respectively, in the littoral zone of Lake Mochou; The mean fluxes were −36.9 mgCO2 m−2 h−1 and 109.8 μgCH4 m−2 h−1, respectively, in the littoral zone of Lake Tuanjie. Their fluxes showed large temporal and spatial dynamics. The CO2 fluxes showed a significantly negative correlation with daily total radiation (DTR) and a weakly negative correlation with air temperature and water temperature, indicating that sunlight intensity controlled the magnitude of CO2 fluxes from the open lakes. The CH4 fluxes significantly correlated with local air temperature, water table and total dissolved solids (TDS), indicating that they were the predominant factors influencing CH4 fluxes. Summertime CO2 budgets in the littoral zones of Lake Mochou and Lake Tuanjie were estimated to be −152.9 gCO2 m−2 and −79.7 gCO2 m−2, respectively, and net CH4 emissions were estimated to be 312.3 mgCH4 m−2 and 237.2 mgCH4 m−2, respectively. Our results show that shallow, open, alga-rich lakes might be strong summertime CO2 absorbers and small CH4 emitters during the open water in coastal Antarctica.