Sediment respiration drives circulation and production of CO ₂ in ice-covered Alaskan arctic lakes [1]

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 m22 d21 in a 3 m deep lake and 45 mg C m22 d21 in four larger lakes, similar to experimental
observations at temperatures below 48C. 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.