|Lischeid, G: Concervative mixing or chemically reacting: scale-dependency of processes at the stream water - groundwater interface, Proc. Symp. 6th IAHS Asientic Assembly, Maastricht, July 2001, Impact of Human Activity on Groundwater Dynamics, 269, 199-204 (2001)|
Due to hypoxic conditions, the riparian zone at the interface between groundwater and stream water can have substantial impacts on stream water quality. This was investigated in a small-forested catchment. The extension of the hypoxic zone was determined by depth oriented groundwater sampling and a steel rod survey. Concentrations of the major solutes were determined simultaneously in the stream water, the shallow and the deeper groundwater. Based on the steel rod survey, the first order stream is entirely contained within a thin hypoxic zone above the deeper oxic aquifer. In general, hypoxia has an impact on NO[-], Fe and Mn, but not on SO[2-] concentrations in the shallow groundwater and the stream water. However, during storm flow, this zone is by-passed by a substantial portion of the runoff, which occurs in the topsoil layer above the hypoxic zone.