ABSTRACT
Large scale geochemical processes were investigated in the river-recharged aquifer of the Oderbruch polder. As a consequence of intensive drainage activities in the past 250 years, river water infiltrates permanently into this shallow confined aquifer. A lateral sequence of redox zones, characterized by either the presence or absence of a redox species, can be found with increasing time and travel distance in the aquifer. Up to 3 km from the river, reduction processes from oxygen respiration to sulfate reduction dominate the groundwater chemistry. Further inland, changing hydraulic conditions cause a predominant influence of the seepage water on the groundwater, resulting in a high sulfate, low pH zone.
