Detailed groundwater monitoring was carried out within a previous research project in an anoxic, river recharged, pleistocene aquifer in the Oderbruch polder in Germany. First results from tritium/helium (³H/³He) age dating were promising and showed that the groundwater recharged by bank filtration gets progressively older with distance from the river. In the central polder region, the input of younger seepage water through the unsaturated zone could be demonstrated qualitatively. In a follow-up project transport processes within the aquifer are evaluated on a larger scale, using the tritium/helium age dating method. The emphasis is on the mapping of the nuclear tritium peak in order to quantify dispersion and and flow velocities in the aquifer. An additional aim is to quantify the recharge through the unsaturated zone in the central polder areas. The outcome will be used to evaluate reaction rates and geochemical fluxes in the anoxic aquifer.