Trace gases like carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) are generated in soil through microbial transformations of carbon and nitrogen species. Respiration of soil organic matter (SOM) in forest, savanna, grassland, and cultivated soils produces CO₂ emissions that represent about 40% of the total emissions from the Earth’s surface. Anaerobic decomposition of SOM in high-latitude wetland and permafrost soils contributes approximately 40% of the source of CH₄ to the atmosphere. About 25% of the global source of N₂O is generated by denitrification in cultivated soils. Future emissions of CO₂, CH₄, and N₂O from the pedosphere are expected to be altered by rising temperatures, wildfires, drought, and more frequent, intense rainfall events. Thus, a mechanistic understanding of the physical, chemical, and biological processes that produce and transport biogenic trace gases within soils and across the soil-atmosphere interface is key to predicting future emissions.

Next generation, process-scale models of land ecosystem-atmosphere exchange will include soil biogeochemical models with enzyme-explicit representations of microbial function, microbe interactions with the soil physicochemical environment, and coupling of macronutrient cycles. Advances in the mass spectrometric analysis of dissolved- and solid-phase SOM have made it possible to visualize and quantify changes in the molecular composition of metabolic intermediates on seasonal and decadal time scales. Molecular biological methods are now used to investigate the composition and activity of the soil microbial community. We welcome manuscripts on process-scale investigations and modeling studies of (1) the biogeochemistry of SOM across diverse ecosystems (e.g., forest, savanna, grassland, wetland, permafrost, and cultivated soils), (2) enzyme kinetics for microbial substrates in soil, and (3) the exchange of trace gases across the soil-atmosphere interface. Submissions are also encouraged on the effects of environmental change on the dynamics of SOM and trace gas emissions from the pedosphere.

To gather further insights into (1) the dynamics of SOM in forest, savanna, grassland, wetland, permafrost, and cultivated soils and (2) the emissions of trace gases from the surface, we welcome articles addressing, but not limited to, the following themes:

• Advances in enzyme-specific modeling of microbial activities in soil
• Integration of molecular biological techniques to assess soil microbial communities
• Effects of environmental change on the seasonal and decadal dynamics of SOM
• Process-scale modeling of biogeochemical cycles and land-atmosphere gas exchange
• Laboratory investigations into the enzyme kinetics of microbial substrates in soils

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Biogeochemistry of Organic Matter and Trace Gas Emissions from the Pedosphere