Geogenic arsenic and uranium in Germany: Large-scale distribution control in sediments and groundwater

Arsenic (As) and uranium (U) are naturally occurring trace elements with potentially adverse effects on human health. This work revisits nine case studies on As/U accumulation and remobilization mechanisms in aquifers with different geological and stratigraphical backgrounds to develop a systematic overview of Germany's geogenic inventory of these trace elements. It uses geochemical proxies for a total of 270 solid samples to explain their spatio-temporal distribution: while Pleistocene geological development can explain their extensive absence in sediments and related groundwater in northern Germany, their abundance and distribution in the central and southern parts are widely controlled by sediment provenance geochemistry. Only highly felsic origin (Moldanubian Variscides) enables creation of elevated U in the systems while lower degrees of provenance felsicity (Rhenohercynian Variscides) appear to be sufficient for As presence. Postdepositional (hydro)geological and anthropogenically triggered intra-basinal processes of trace element accumulation, redistribution and eventually remobilization to groundwater contribute to the present-day situation. Therefore, the ultimate control of these incompatible trace elements is magmatic, even in old sedimentary systems, and still clearly traceable in nowadays large-scale geogenic As and U distribution in Germany and probably elsewhere.