Determining soil organic matter quality under anaerobic conditions in arctic and subarctic soils

The rate of anaerobic respiration by soil microbes depends on many factors including water and nutrient availability, pH, temperature, oxidation–reduction potential, and soil organic matter (SOM) quality. Anaerobic respiration produces the greenhouse gases, carbon dioxide (CO2) and methane (CH4). The impact of SOM quality on anaerobic respiration rates is important but not well understood. This study investigated the dependence of anaerobic respiration on specific components of SOM in arctic and subarctic soils. A model was then developed to describe this dependence. Using the model, a suite of components from SOM was used to describe SOM quality. asure for SOM quality was developed by incubating a suite of arctic and subarctic soils under SOM limiting conditions. Pyrolysis-gas chromatography/mass spectrometry analysis was used to determine which components of SOM contributed to high respiration rates. The SOM quality of a given soil could then be determined based on the relative abundance of components known to contribute to high respiration rates. The model developed from this relationship was then applied to soil samples taken from the Smith Lake methane flux site at the University of Alaska Fairbanks in order to estimate the SOM quality from soils in this area.