Pyrite oxidation processes in cretaceous sedimentary rock | Pyritoxidationsprozesse im cretazischen Emschermergel infolge von aeroben Bedingungen durch den Emscherumbau
2015
Droste, Björn | Wisotzky, Frank
Due to the restoration of the Emscher river system, large amounts of the Emschermergel, a Cretaceous sediment containing significant amounts of carbonate and pyrite, will be released from its anoxic state. The oxidation of pyrite results in the release of protons, iron and sulfate. In order to evaluate the impact of the reaction products, extensive laboratory investigations were carried out. The methodology can detect pyrite content in the range of magnitude of the Rhenish lignite mining area (average 0.21 wt.% Pyritic-S). The formation of a naturally-occurring weathering horizon could also be detected. Under laboratory conditions, further oxidation of the weathered laboratory samples could be observed. Column experiments show significant release of sulfate at high concentrations. Hydrochemical modelling and acid-base accounting show neutralization of the free protons by the effective carbonate buffer in the sediment.
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