Microbial sulfate reduction within sulfidic mine tailings: Formation of diagenetic Fe sulfides

Most microbiological studies of sulfidic mine tailings impoundments have concentrated on the chemolithotrophic bacteria contained within the oxic zone and their ability to promote the production of toxic leachates. Few studies have looked at the anoxic zone and the possibility of the existence of sulfate‐reducing bacteria (SRB). Our study of the Kidd Creek mine tailings (Cu‐Zn ore) reveals not only the existence of SRB in this sulfur‐rich environment, but also the importance of their role in iron and sulfur cycling. Sulfur metabolism and subsequent H₂S production of SRB, together with the highly reactive surface of the cells, promote the development of a variety of sulfide minerals. Diagenetic amorphous FeS, mackinawite (FeS_1‐X), and pyrite were found within the tailings where high populations of SRB were present. In addition, those Fe sulfide minerals served as sorption substrates for other dissolved species, such as Cu and Zn.

Keywords:

• Fe sulfides
• mine tailings
• sulfate‐reducing bacteria