Organic matter and trace gas turnover in northeast Siberian permafrost: First soil studies on the impact of climate change on carbon mineralization
Zusammenfassung der Projektergebnisse
The degradability of organic matter in permafrost sediments and soils was quantified to estimate the potential release ofthe climate relevant trace gases CO2 and methane from the carbon rich permafrost deposits of north-east Siberia. A variety of soil and sediment samples, representing Pleistocene to Holocene material containing a wide range of organic matter (0.2 - 12%) were incubated for almost 1 year under aerobic and anaerobic conditions. The release of CO2 correlated with the amount of organic matter in the permanently frozen ground. As expected, highest CO2 production was measured in the seasonally unfrozen layer at the soil surface, where fresh organic matter was available. However, if only the permanently frozen material was considered, highest turnover rates were found in the old. Pleistocene (40.000 y BP) accumulations of organic matter and not in those of Holocene age close to the surface. These results indicate that after thawing also the relatively old organic matter in permafrost deposits might be rapidly respired to CO2. Considering that current estimates on the amount of carbon potentially released from Siberian permafrost are based on a handful of samples, these findings contribute significantly to our knowledge on the degradability of organic matter in permafrost.
