| Three sets of experiments were performed to investigate the role of heterotrophic and chemolithoautotrophic microbial growth on the release and speciation of arsenic in a simulated acid mine drainage environment. Pure cultures of A. ferrooxidans and A. cryptum were added to mineral solutions of pyrite, pyrite and orpiment, orpiment, or arsenopyrite.;Mixed A. ferrooxidans and A. cryptum systems exhibited lower arsenic release and a shift in the speciation to As(V)-dominated dissolved species. This is significant because remediation efforts which focus on encouraging heterotrophic growth may also lower arsenic release to the environment. A. cryptum was found to have the ability to oxidize As(III) to As(V) during aerobic growth in the absence of other electron donors. In this mode of growth, As(III) served as the electron donor and oxygen was the terminal electron acceptor. (Abstract shortened by UMI.). |
