Microbial sulfate reduction and metal attenuation in pH 4 acid mine water

• Published in: Geochemical transactions GT Vol. 8; no. 1; p. 10
• Main Authors: Church, Clinton D, Wilkin, Richard T, Alpers, Charles N, Rye, Robert O, McCleskey, R Blaine
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 23-10-2007; Springer Nature B.V; BioMed Central; BMC
• Subjects: Abandoned mines; Acid mine drainage; Acid mine water; Anaerobic bacteria; Anaerobic conditions; Anaerobic processes; Analysis; Analytical methods; Attenuation; Bacteria; Biology; Cadmium; Community structure; Copper; Cultures; Dissolved gases; Electrophoresis; Environmental aspects; Fatty acids; Gel electrophoresis; Gels; Heavy metals; Hydrogen sulfide; Hydrogen-ion concentration; Iron; Iron sulfides; Isotope ratios; Microorganisms; Mine accidents; Mine drainage; Mine flooding; Mine water; Molecular biology; Nucleotide sequence; Oxidation; pH effects; Phospholipids; Phylogenetics; Phylogeny; Physiological aspects; Precipitates; Properties; rRNA 16S; Scanning electron microscopy; Sediment; Sediments; Sediments (Geology); Stable isotopes; Sulfate reduction; Sulfate-reducing bacteria; Sulfates; Sulfide minerals; Sulfides; Sulfur; Sulphate reduction; Sulphates; Sulphides; Sulphur; Surface water; Underground mines; Zinc; United States
• ISSN: 1467-4866; 1467-4866
• DOI: 10.1186/1467-4866-8-10

Sediments recovered from the flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4.0 to 7.5). The molecular biology of sediments and cultures was studied to determine whether sulfate-reducing bacteria (SRB) were active in moderately acidic conditions present in the underground mine workings. Here we document multiple, independent analyses and show evidence that sulfate reduction and associated metal attenuation are occurring in the pH-4 mine environment. Water-chemistry analyses of the mine water reveal: (1) preferential complexation and precipitation by H2S of Cu and Cd, relative to Zn; (2) stable isotope ratios of 34S/32S and 18O/16O in dissolved SO4 that are 2-3 per thousand heavier in the mine water, relative to those in surface waters; (3) reduction/oxidation conditions and dissolved gas concentrations consistent with conditions to support anaerobic processes such as sulfate reduction. Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates. Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria. Cultures of sediment from the mine produced dissolved sulfide at pH values near 7 and near 4, forming precipitates of either iron sulfide or elemental sulfur. DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures.