Hydrology, electron acceptor availability and organic matter decomposition in Dutch peatland pastures

The Netherlands plans to cut greenhouse gas emissions by 1 megaton CO₂-equivalents in 2030 by implementing measures reducing peat decomposition. In order to achieve this, a national research program on peatland pasture greenhouse gas emissions has been set up. In the program, five peatland sites with each two fields, with and without submerged tube drainage systems, are continuously monitored. Here, we present our research with the objective to understand the rate of biochemical peat decomposition by assessing electron acceptor availability from a hydrological perspective. Soil (< 100 cm depth) redox conditions are continuously measured at five depths. Preliminary data on soil electron acceptor availability distribution suggest counterintuitive behavior of the peat soils. We find reducing conditions in the topsoil (0-20 cm) and oxidative conditions in the subsoil (40-80 cm) for the sites without tube drainage. For sites with tube drainage, we find oxidative conditions in the topsoil (0-20 cm) and reducing conditions starting at 60 cm depth at the drain location and at 80 cm depth between the drains. A novel 2D groundwater model is being set up, enabling to capture saturation dynamics, water origin and solute transport in the peat soil. We will present our modelling setup and initial simulation results for water origin and travel paths. These results will indicate how electron acceptors are distributed through the soil, helping to interpret redox measurements in the field at different depths. In a later stage of the research, the effects of redox conditions on microbial soil respiration will be evaluated with greenhouse gas chamber and eddy covariance measurements.