Paper No. 104-7
Presentation Time: 9:00 AM-6:30 PM
VARIABILITY IN THE TEMPERATURE SENSITIVITY OF ANOXIC ORGANIC MATTER DECOMPOSITION
Temperature sensitivity is a key feature of microbial processes that regulates biological carbon emissions in natural environments. This feature is commonly quantified as Q10, the rate change over a temperature interval of 10 °C . Here we apply biogeochemical modeling to analyze the temperature sensitivity of anerobic degradation of organic matter and its dependence on substrate concentrations, biomass abundance, and microbial interactions. We first carry out a meta-analysis of Q10 values determined previously, and the results show that cold areas such as arctic and tundra soils can have higher Q10 values reaching over 200, wherase in temperate and tropical areas, the Q10 values range from as small as 1.5 to near 3.5. We then simulate the anaerobicdegradation of butyrate, a key intermediate of organic matter decomposition, at temperatures ranging from 5 to 50 ℃ in a closed environment. We also simulate the anaerobic degradation of natural organic matter acorss the different temperatures in a semi-open enviroment. Our modeling-derived Q10 values vary from 1 to over 400, within the ranges reported by previous laboratory and field experiments [2,3]. The results show that the temperature sensitivity tend to be larger at lower temperatures, and can be accounted for by the concurrent responses of reaction thermodynamics and biomass concentrations. In addition, the Q10 values are also shaped by biogeochemical conditions, including substrate concentrations and microbial interactions. These results suggest that Q10 might not always capture the complexity of temperature sensitivity of biogeochemical processes, and its application deserves additional considerations of how different environmental factors work together in determining the kinetics of biogeochemical processes.
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