Bioavailability of jarosite for stimulating acid mine drainage attenuation
2012
Biological reduction of iron-sulfate minerals, such as jarosite, has the potential to contribute to the natural attenuation of
acid mine drainage (AMD) sites. Previous studies of AMD attenuation at Davis Mine, an abandoned pyrite mine in Rowe
Massachusetts, provided evidence of iron and sulfate reduction by indigenous bacteria. Jarosite is a large component of the
sediment at Davis Mine and may play a role in AMD attenuation. In this study, microcosms were constructed with groundwater
and sediment from Davis Mine and amended with glycerol, nitrogen and phosphorus (GNP) and naturally formed
natrojarosite. Over time, higher total iron, sulfate, pH and sodium concentrations and lower oxidation–reduction potentials
were observed in microcosms amended with GNP and jarosite, compared with unamended microcosms and killed controls.
Geochemical modeling predicted jarosite precipitation under microcosm conditions, suggesting that abiotic processes were
unlikely contributors to jarosite dissolution. SEM imaging at the jarosite surface showed microbial attachment. Microbial
community composition analysis revealed a shift to higher populations of Clostridia, which are known to reduce both iron
and sulfate. The results show that jarosite may be utilized as an electron acceptor by iron and/or sulfate reducing bacteria
at Davis Mine and its presence may aid in the attenuation of AMD.
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