Hydrogeomorphic controls on reduction-oxidation conditions across boreal upland-wetland interfaces

This study is presented as two separate papers in order to (1) examine the spatiotemporal dynamics of the redox state of groundwater along upland-wetland transitions of different geomorphic settings and (2) to assess how fluctuations in water table affect wetland redox conditions. It was found that geomorphic setting and its subsequent control on hydrology resulted in high amounts of spatial variability in redox chemistry across the upland-wetland interface and that event-driven lateral groundwater flow from the surrounding uplands was the primary temporal control on changes in both redox chemistry and in situ redox potential. Decreases in water table elevation for longer durations resulted in large, short-term increases in sulfate concentration as a result of sulfide re-oxidation after the water table was increased.