title: Soluble microbial products decrease pyrite oxidation by ferric iron at pH < 2.
abstract: Research on microbial activity in acid mine drainage (AMD) has focused on transformations of iron and sulfur. However, carbon cycling, including formation of soluble microbial products (SMP) from cell growth and decay, is an important biogeochemical component of the AMD environment. Experiments were conducted to study the interaction of SMP with soluble ferric iron in acidic conditions, particularly the formation of complexes that inhibit its effectiveness as the primary oxidant of pyrite during AMD generation. The rate of pyrite oxidation by ferric iron in sterile suspensions at pH 1.8 was reduced by 87% in the presence of SMP produced from autoclaved cells at a ratio of 0.3 mg DOC per mg total soluble ferric iron. Inhibition of pyrite oxidation by SMP was shown to be comparable to, but weaker than, the effect of a chelating synthetic siderophore, DFAM. Two computational models incorporating SMP complexation were fitted to experimental results. Results suggest that bacterially produced organic matter can play a role in slowing pyrite oxidation.
authors.affiliation: Departments of Civil, Environmental, and Architectural Engineering, University of Colorado , 428 UCB, ECOT 441, Boulder, Colorado 80309, United States. yacob@colorado.edu
authors.forename: Tesfayohanes
authors.initials: T
authors.lastname: Yacob
authors.forename: Sachin
authors.initials: S
authors.lastname: Pandey
authors.forename: Joann
authors.initials: J
authors.lastname: Silverstein
authors.forename: Harihar
authors.initials: H
authors.lastname: Rajaram
mesh_terms: D002614:Chelating Agents / Q000737:chemistry; D005290:Ferric Compounds / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism*; D008956:Models, Chemical; D010084:Oxidation-Reduction; D013440:Sulfides / Q000378:metabolism*
chemical_list: D002614:Chelating Agents; D005290:Ferric Compounds; D013440:Sulfides; C011342:pyrite; D007501:Iron