Heterotrophic bacterio‐plankton in thawed lakes of the northern part of Western Siberia controls the CO₂ flux to the atmosphere

Abstract

This work reports on results of bacterio‐plankton characterisation in thaw lakes of the northern part of Western Siberia via measurement the number of various groups of heterotrophic bacteria and the intensity of primary production/respiration in the water column. The eutrophic systems at the beginning of lake formation (permafrost thawing) are being replaced by essentially oligotrophic systems at the final, mature stage of the lake development (khasyrey). The CO₂ flux from the lake surface to the atmosphere associated with microbial degradation of organic matter (107 ± 50 t C/km²/y) is at least one order of magnitude higher than the riverine organic carbon flux. The future climate evolution in this region, consisting in rising ground temperature and precipitation increase will bring about further acceleration of dissolved organic matter degradation in the water column and amplification of CO₂ release to the atmosphere.

Keywords:

• Lake
• Thaw
• Permafrost
• Bacteria
• Carbon
• Siberia

Acknowledgements

This work was supported by the joint CNRS/RFBR project–RFBR 08‐05‐92496 ‘Thermokarst lakes dynamics of West‐Siberian cryolithozone as an indicator of climatic changes (on the data of remote sensing and ground‐based observations)’, the EC2CO programme and CAR‐WET‐SIB ‘Biogeochemical cycle of carbon in wetlands of Western Siberia GDRI (Groupement de recherche international) Car‐WET‐SIB network project.

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