Sediment respiration drives circulation and production of CO2 in ice-covered Alaskan arctic lakes

Abstract

The goals of our study were to (1) quantify production of CO2 during winter ice-cover in arctic lakes, (2) develop methodologies which would enable prediction of CO2 production from readily measured variables, and (3) improve understanding of under-ice circulation as it influences the distribution of dissolved gases under the ice. To that end, we combined in situ measurements with profile data. CO2 production averaged 20 mg C m−2 d−1 in a 3 m deep lake and ∼ 45 mg C m−2 d−1 in four larger lakes, similar to experimental observations at temperatures below 4°C. CO2 production was predicted by the initial rate of loss of oxygen near the sediments at ice-on and by the full water column loss of oxygen throughout the winter. The time series data also showed the lake-size and time dependent contribution of sediment respiration to under-ice circulation and the decreased near-bottom flows enabling anoxia and CH4 accumulation.