Microbially mediated sulfate reduction is a promising cost-effective and sustainable process utilized in permeable reactive barriers (PRB) and constructed wetlands to treat mine wastewater. Laboratory batch experiments were performed to evaluate nickel (Ni) isotope fractionation associated with precipitation of Ni-sulfides in the presence of the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricansT (DSM-642). Precipitates were collected anaerobically and characterized by synchrotron powder X-ray diffraction (PXRD), scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS), and transmission electron microscopy (TEM). Solid-phase analyses showed that the precipitates associated with bacteria attached to the serum bottle walls were characterized by enhanced size and crystallinity. Lighter Ni isotopes were preferentially concentrated in the solid phase, whereas the solution was enriched in heavier Ni isotopes compared to the input solution. This fractionation pattern was consistent with closed-system equilibrium isotope fractionation, yielding a fractionation factor of Δ60Nisolid‑aq = −1.99‰. The Ni isotope fractionation measured in this study indicates multiple Ni reaction mechanisms occurring in the complex SRB-Ni system. The results from this study offer insights into Ni isotope fractionation during interaction with SRB and provide a foundation for the characterization and development of Ni stable isotopes as tracers in environmental applications.
Bibliographical noteThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Environmental Science and Technology © after peer review and technical editing by the publisher. To access the final edited and published work see https://dx.doi.org/10.1021/acs.est.2c00523
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Funding Information: This project was funded by a Natural Sciences and Engineering Research Council (NSERC) Strategic Project Grant (NETGP 479708-15; D.W.B., Principal Investigator), an Ontario Research Fund-Research Excellence grant (RE09-061; awarded to D.W.B., C.J.P., and R.P.), and an NSERC Discovery Grant (RGPIN-2019-07118; awarded to D.W.B.). Portions of the research described in this paper were performed at the Canadian Light Source, which is supported by the Canada Foundation for Innovation, Natural Sciences and Engineering Research Council of Canada, the University of Saskatchewan, the Government of Saskatchewan, Western Economic Diversification Canada, the National Research Council Canada, and the Canadian Institutes of Health Research.
- nickel isotopes
- sulfide precipitation
ASJC Scopus subject areas
- Environmental Chemistry