Environmental relevance monitoring and assessment of ochreous precipitates, hydrochemistry and water sources from abandoned coal mine drainage.

This study investigated the mineralogical and chemical characteristics of ochreous precipitates and mine water samples from abandoned Upper Carboniferous hard coal mines in an extensive former mining area in western Germany. Mine water characteristics have been monitored and assessed using a multi-methodological approach. Thirteen mine water discharge locations were sampled for hydrochemical analysis, with a total of 46 water samples seasonally collected in the whole study area for stable isotopic analyses.

Modified microbiology through enhanced denitrification by addition of various organic substances-temperature effect.

Worldwide, the environmental nitrate (NO) problem is increasingly coming into focus. These increases in NO concentration result mainly from agricultural inputs and are further exacerbated by decreasing and finite geogenic NO degradation capacity in aquifers. Thus, treatment methods are becoming more and more important.

Denitrification in the vadose zone: Modelling with percolating water prognosis and denitrification potential.

Transport and transformation processes of nitrogen in the soil are an essential part of understanding the relationship between agricultural input and nitrate (NO) concentrations in groundwater. The presented study describes these transformation processes around NO degradation at a water catchment in the Lower Rhine Embayment, Germany. Despite intensive agriculture, extracted groundwater at a depth of 21 to 22 m shows unexpectedly very low NO levels, below 3 mg/L NO for all wells.

Forecasting nitrate evolution in an alluvial aquifer under distinct environmental and climate change scenarios (Lower Rhine Embayment, Germany).

When investigating future nitrate (NO) concentrations in groundwater, climate change has a major role as it determines the future water budget and, in turn, the conditions in the aquifer which will finally have a decisive effect on NO concentrations. In this study, the different effects on water balance and NO concentration under three projected climate scenarios - RCP 2.6, RCP 4.

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.

Drinking Water Uranium and Potential Health Effects in the German Federal State of Bavaria.

Mainly due to its nephrotoxic and osteotoxic potential, uranium (U) increasingly finds itself in the spotlight of environmental and health-related research. Germany decided on a binding U guideline value in drinking water of 10 µg/L, valid since 2011. It is yet widely unknown if and how public health was affected by elevated U concentrations before that.

Ex situ groundwater treatment triggering the mobilization of geogenic uranium from aquifer sediments.

Uranium (U) concentrations in groundwater extracted for drinking water usage from a Quaternary fluvial aquifer partly exceed the German drinking water guideline of 10μgL. Responsible sources and mobilization processes were unknown and gave rise to this study. Land use of the watershed is mainly agricultural leading to groundwater nitrate concentrations >50mgL and a need for water treatment prior to utilization as drinking water.

Groundwater uranium origin and fate control in a river valley aquifer.

Groundwater in a Quaternary gravel aquifer partly exhibits uranium (U) concentrations exceeding the new German drinking water limitation (22% of the samples >10 μg L(-1)). This study assesses relevant U reservoirs and hydrogeochemical processes responsible for U transfer between them. A large data set of solid materials (sediments and soils, 164 samples total) and groundwater (114 samples total) characteristics was created in terms of geo- and hydrochemistry, mineralogy, U microdistribution, and mobilization potential.

Crossing redox boundaries--aquifer redox history and effects on iron mineralogy and arsenic availability.

Cretaceous shallow marine sediments from northwestern Germany exhibit a distinct colour and geochemical boundary in a depth of several decametres, witnessing a terrestrial oxidative paleo redox process which resulted in cement loss and oxidation of Fe(II) phases. Sediment samples were obtained from boreholes drilled in near-coastal and further basinward paleo environments, including both reduced and oxidized redox facies, to characterize As and Fe occurrence in unaltered layers and redistributional consequences of the redox event. Geochemical and mineralogical composition and As fractionation were assessed.

Enrichment processes of arsenic in oxidic sedimentary rocks - from geochemical and genetic characterization to potential mobility.

Sedimentary marine iron ores of Jurassic age and Tertiary marine sandy sediments containing iron hydroxides concretions have been sampled from boreholes and outcrops in two study areas in Germany to examine iron and arsenic accumulation processes. Samples were analyzed for bulk rock geochemistry (INAA/ICP-OES), quantitative mineralogy (XRD with Rietveld analysis), element distribution (electron microprobe) and arsenic fractionation (sequential extraction). Bulk Jurassic ores contain an average arsenic content of 123 μg g(-1) hosted in mainly goethite ooids which slowly formed in times of condensed sedimentation.