Reductive dissolution of trace metals from sediments

Abstract

The reactivity of trace elements in lake sediments towards microbial metal reduction was evaluated using spectroscopy, chemical extractions and incubations in a minimal media with the DIR bacterium Shewanella putrefaciens 200R. Micro-XRF measurements demonstrated the association of Cr, and Ni with Mn-rich phases. The onset of anaerobic conditions resulted in the rapid release of trace metals (Cr, Ni, Co) from the sediments with the progressive dissolution of a reactive Mn component. This fraction was approximately equivalent to that liberated by chemical extractions designed to operationally select for Mn phases. These results suggest that studies aiming to assess metal dissolution in anaerobic soils and sediments should attempt to discriminate between metals associated with Mn and Fe (hydr)oxides, the former being more reactive and likely dissolved to a greater extent.