H2 formation and release during temporary anoxic periods in soils – an unanticipated process with implications for the residence of greenhouse gases in the atmosphere
Person photo Prof Patrick Crill
Department of Geological Sciences

Funding source: Formas - The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning
Period: 1/1/08 - 12/31/10
Funding: 3220000 SEK
Description:
Molecular hydrogen (H2) plays an important role in atmospheric oxidation/reduction chemistry due to its reactions with OH and as a source of water vapor to the troposphere and stratosphere. This makes H2 an indirect greenhouse gas. However, the atmospheric source/sink relationships controlling its global warming potential and chemistry are very uncertain. To date, soils have been considered only as a sink consuming H2. However, soil biogeochemistry should also play an important role in the production and emission of H2, which is ultimately governed by the soil redox conditions for the microorganisms involved. The aims are : 1) to quantify the atmospheric exchange of H2 from boreal and sub-arctic soils; and 2) to identify the underlying microbiological processes of its production and consumption. Our hypotheses are: 1) Hydrogen emissions to the atmosphere take place during temporary anoxia in soils rich in organic matter; 2) Thus, emissions will occur as a result of rain events causing anaerobic conditions during any time of the growing season as well as during freeze-thaw cycles, when easily degradable organic matter is released and water saturation often takes place. Through field and laboratory investigations on forest an mire soils we will resolve temporal and spatial variations in the biogeochemical processes governing net exchange of H2 and its sensitivity to key environmental variables.
  
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Linköping University,
Sweden