Environmental Effects of Western Coal Surface Mining. Part IV--Chemical and Microbiological Investigations of a Surface Coal Mine Settling Pond

摘要

Chemical and microbiological investigations of the settling pond system at the West Decker Coal Mine in southeastern Montana were undertaken during 1975-1977. Concentrations of total dissolved solids, bicarbonate, sodium, sulfate, and nitrogen species in pond water were elevated in comparison to those in other nearby surface waters; however, it was concluded that these would not significantly impact the nearby Tongue River or Tongue River Reservoir. Constituents of the mine drainage waters underwent chemical changes within the pond which were at least in part due to the activities of microorganisms. The increase in pH value and in concentration of dissolved oxygen, partially attributed to photosynthesis within the pond, oxidized reduced chemical species such as sulfide and ferrous iron. The high numbers and activity measurements of sulfate reducing bacteria as well as the significant amount of metal-bound sulfides in pond sediments made a strong case for the contributions of these organisms to metal precipitation in, and possible detoxification of, pond waters.