Iron isotope fractionation by biogeochemical processes in mine tailings
2008 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 42, no 4, 1117-1122 p.Article in journal (Refereed) Published
Iron isotope ratios were determined for the pore water, the 1M HCl / 1M hydroxylamine hydrochloride (HAH) – extractable solid phase, and the total extractable solid phase from sulfidic mine tailings in Impoundment 1, Kristineberg mine, northern Sweden. Within the tailings, pyrite oxidation occurs in a distinct Fe – depleted oxidation zone, and the greatest number of Fe(II)-oxidizing bacteria in the profile occur close to the boundary between oxidized and unoxidized tailings. Above the oxidation front in the oxidized tailings, a large iron isotope fractionation (‑1.3‰ to ‑2.4‰) is measured between the pore water and the HAH-extractable solid phase. This isotope fractionation is explained by aqueous Fe(II) –
Fe(III) equilibrium, microbial Fe(II) oxidation, and Fe(III) oxyhydroxide precipitation. The data suggests that pyrite in the tailings is enriched in 56Fe relative to Fe-rich silicates in the same material, such that pyrite oxidation results in a decrease in the mean d56Fe value for the bulk tailings in the oxidized zone: a change in isotope composition that is not attributable to isotope fractionation. Iron isotope analyses yield valuable information on iron cycling in mine wastes, and have the potential for becoming a tool for the prediction and control of acid mine drainage.
Place, publisher, year, edition, pages
2008. Vol. 42, no 4, 1117-1122 p.
iron isotopes, mine tailings, pyrite oxidation, Acidithiobacillus ferrooxidans
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:uu:diva-86520DOI: 10.1021/es071616sISI: 000253250800028OAI: oai:DiVA.org:uu-86520DiVA: diva2:117334