Stable isotope geochemistry of acid mine drainage from the Wisniowka area (south-central Poland)

摘要

This paper presents the results of a current isotopic study of pyrite mineralization, acid mine drainage (AMD), and nearby rivers and farmer's wells located in the western part of the Main Range, Holy Cross Mountains (southcentral Poland). The principal source of dissolved sulfates in acid lakes, ponds and intermittent pools is the predominant microscopic-grained and locally framboidal pyrite (FeS2) that tends to oxidize rapidly on exposed quarry walls and unvegetated historic and current tailings piles. This process is expedited by the occurrence of arsenic in the pyrite crystal structure, which greatly decreases its resistance to weathering. The delta S-34 signature of pyrite from the Podwisniowka quarry (mean of -24.0 +/- 3.1 parts per thousand) was different from that of the Wisniowka Dua. quarry (mean of -17.4 +/- 7.2 parts per thousand). These values fingerprinted two basic pyrite mineralization zones assigned to lowermost and middle Upper Cambrian rock series, respectively. The delta S-34-FeS2 differences also were reflected in dissolved sulfates that displayed distinctly different delta S-34 values: -15.3 +/- 1.0 parts per thousand (Podwisniowka) and -10.0 +/- 1.7 parts per thousand (Wisniowka Dua.). These negative delta S-34 values stand in contrast to their positive equivalents of the Cambrian Main Range, as well as in the examined rivers and farmer's wells unaffected by AMD processes. The acid water bodies also displayed diverse seasonal variations of delta S-34-SO42-, delta O-18-SO42- and delta O-1(8)-H2O that were linked to surface area, site topography, exposition to radiation, changing weather patterns, especially temperature and a periodical influx of rainwater or meltwater. The isotope data also suggest that evaporation occurred after pyrite oxidation without a direct contact with lake/pond waters, which is also evidenced by the occurrence of sulfate efflorescences on Podwisniowka and Wisniowka quarry faces. The stable S, O and H isotopes have been