Linking Soil O^sub 2^, CO^sub 2^, and CH^sub 4^ Concentrations in a Wetland Soil: Implications for CO^sub 2^ and CH^sub 4^ Fluxes

Oxygen (O2) availability and diffusivity in wetlands are controlling factors for the production and consumption of both carbon dioxide (CO2) and methane (CH4) in the subsoil and thereby potential emission of these greenhouse gases to the atmosphere. To examine the linkage between high-resolution spatiotemporal trends in ...availability and ... dynamics in situ, we compare high-resolution subsurface ... concentrations, weekly measurements of subsurface ...concentrations and near continuous flux measurements of ... and ... Detailed 2-D distributions of ... concentrations and depth-profiles of ... and ... were measured in the laboratory during flooding of soil columns using a combination of planar ... optodes and membrane inlet mass spectrometry. Microsensors were used to assess apparent diffusivity under both field and laboratory conditions. Gas concentration profiles were analyzed with a diffusion-reaction model for quantifying production/consumption profiles of ..., ..., and ... In drained conditions, ... consumption exceeded .. production, indicating ... dissolution in the remaining water-filled pockets. ...emissions were negligible when the oxic zone was >40 cm and ... was presumably consumed below the depth of detectable ... In flooded conditions, ... was transported by other mechanisms than simple diffusion in the aqueous phase. This work demonstrates the importance of changes in near-surface apparent diffusivity, microscale ... dynamics, as well as gas transport via aerenchymous plants tissue on soil gas dynamics and greenhouse gas emissions following marked changes in water level. (ProQuest: ... denotes formulae/symbols omitted.)