科研之友
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摘要
The hydrogeochemistry of the Cretaceous Emscher Fm. in northwest Germany was investigated, including analysis of 160 rock samples for carbon and sulfur content. Beneath a weathered zone, unweathered rocks containing pyrite were found. Groundwater data from the Emscher Fm. (580 analyses of house wells and additional literature data) were collected and evaluated. Some groundwater contains high fluoride and boron concentrations of up to 10 mg/l. Regionally, up to 30% of house wells show fluoride concentrations above 1.5 mg/l, and up to 50% above 1 mg/l boron. The spatial distribution depends on the presence of Quaternary cover sediments. Groundwater with high fluoride concentrations displays low Ca2+, and vice versa, indicating equilibrium with the mineral fluorite (CaF2). Concentrations above drinking water guidelines almost exclusively occur in ion exchange waters of the Na-HCO3 (-)(Cl) type with pH > 7.5. The main mobilization mechanism of both contaminants appears to be pH-triggered desorption from mineral surfaces.
- 出版日期2017-3
