Soil heterogeneity effects on O<inf>2</inf>distribution and CH<inf>4</inf>emissions from wetlands: In situ and mesocosm studies with planar O<inf>2</inf>optodes and membrane inlet mass spectrometry
- Publication Type:
- Journal Article
- Soil Biology and Biochemistry, 2010, 42 (12), pp. 2254 - 2265
- Issue Date:
The importance of soil heterogeneity for methane emission from a wetland soil is assessed by in situ point measurements of depth-specific O2and CH4concentrations and simultaneous soil CH4fluxes at contrasting water levels. Profile measurements, and associated assumptions in their interpretation, were validated in a controlled mesocosm drainage and saturation experiment applying planar O2optodes and membrane inlet mass spectrometry. Results show that peat soil is heterogeneous containing dynamic macropore systems created by both macrofauna and flora, which facilitate preferential flow of water, O2and CH4and vary temporally with changes in the moisture regime. The O2content above the water table after drainage varied horizontally from 0 to 100% air saturation within few mm. Oxic zones were observed below the water level and anoxic zones were observed in layers above the water level in periods up to days after changes in the water level. This study shows that although water table position is a competent proxy of soil CH4fluxes at larger spatio-temporal scales, it becomes inadequate at higher spatial resolution, i.e. at the scale of the soil pedon and below. High resolution O2measurements using planar O2optodes have great potential to enhance our understanding of the effect of the water table position on O2dynamics on scales of several cm to mm in wetland soils. © 2010 Elsevier Ltd.
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