Geoökologisches Kolloquium SS 2007

All lecture dates

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Prof. Dr. Danielle Fortin
Environmental Geomicrobiology Group, University of Ottawa
Thursday, 21.06.2007 16:15 H6

Biogeochemical cycling of iron and sulfur in sulfide-rich mine tailings

Mining activities generate large quantities of waste material, known as mine tailings. In base-metal mines (Cu, Zn, Ni, Pb, etc.), such tailings are often disposed of in open-air impoundments. They contain large amounts of pyrite, which can easily undergo oxidation and generate acid-mine drainage (AMD). Several studies have looked at the microbial and geochemical cycling of iron and sulfur in oxic tailings, but very few have attempted to determine the driving factors behind Fe and S cycling in the anoxic portion of the sediments. Past work in my laboratory has shown that anaerobic bacteria, mainly sulfate-reducing bacteria (SRB) and iron-reducing bacteria (FeRB) are present and active in mine tailings. Their respective activity is however, function of various physico-chemical factors, including temperature (seasonal fluctuations), pH and availability of both electron donors and acceptors. The presentation will focus on the results obtained so far for 2 types of sulfide-rich mine tailings, i.e., acidic Cu-Zn tailings and neutral Pb-Zn tailings in order to show that microbial activity and the subsequent cycling of iron and sulfur at both sites are strongly dependent on the in situ chemical conditions of the sites. The last portion of the presentation will briefly discuss the role SRB and other bacteria in heavy metal (i.e., As and Hg) cycling in mine tailings.

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