HR: 1340h
AN: B13C-1381    [Abstracts]
TI: Sulfide-driven arsenic solubilization from arsenopyrite and pyritic black shale
AU: * Zhu, W
EM: wenyizhu@Eden.Rutgers.edu
AF: Department of Environmental Sciences Rutgers University, 14 College Farm Rd, New Brunswick, NJ 08901, United States
AU: Rhine, E D
EM: drhi@novozymes.com
AF: Biotechnology Center for Agriculture and the Environment, 59 Dudley Road, New Brunswick, NJ 08901, United States
AU: Rhine, E D
EM: drhi@novozymes.com
AF: Novozymes Biologicals, 5400 Corporate Circle, Salem, VA 24153, United States
AU: Young, L Y
EM: lyoung@AESOP.Rutgers.edu
AF: Department of Environmental Sciences Rutgers University, 14 College Farm Rd, New Brunswick, NJ 08901, United States
AU: Young, L Y
EM: lyoung@AESOP.Rutgers.edu
AF: Biotechnology Center for Agriculture and the Environment, 59 Dudley Road, New Brunswick, NJ 08901, United States
AU: Serfes, M E
EM: mserfes@njdep.state.nj.us
AF: New Jersey Geological Survey, PO Box 427, Trenton, NJ 08625, United States
AU: Reinfelder, J R
EM: reinfelder@envsci.rutgers.edu
AF: Department of Environmental Sciences Rutgers University, 14 College Farm Rd, New Brunswick, NJ 08901, United States
AB: Groundwater in the Newark Basin, located primarily in northern New Jersey and Eastern Pennsylvania, locally has arsenic levels in excess of 10 ug L-1 in up to 30% of the water supply wells sampled. One possible source of this arsenic is pyrite in black shale that weathers in ground-water recharge areas. As part of a larger study of microbial arsenic mobilization and transformation in the Newark Basin, we examined the role of sulfide in arsenic mobilization from arsenopyrite, pyritic black shale, and arsenic-rich pyrite. Based on preliminary observations of biologically mediated mobilization of arsenic from Newark Basin black shale under hypoxic (N2 atmosphere) conditions, we hypothesized that sulfide generated by biological activity drives arsenic release from arsenic-rich pyrite. To examine this hypothesis, we conducted a series of sulfide-arsenide exchange experiments with arsenopyrite, pyritic black shale, and arsenic-rich pyrite under oxic (21% O2), hypoxic (1-2% O2, N2), and anoxic (5% H2, 95%N2) conditions. Results show that sulfide (1 mM initial concentration) drives arsenic solubilization from all three solids under hypoxic and oxic, but not anoxic conditions. XANES results show that arsenic in pyrite from Newark Basin black shale has the same oxidation state (-1) as arsenic in arsenopyrite, supporting a proposed sulfide-arsenide exchange mechanism in which sulfide replaces arsenic in arsenopyrite and arsenide is oxidized to arsenite. Since the proposed reaction requires an oxidant in addition to sulfide, it would occur only under conditions of redox disequilibrium in which sulfide and an oxidant transiently co-exist.
DE: 0404 Anoxic and hypoxic environments (4802, 4834)
DE: 0448 Geomicrobiology
DE: 0463 Microbe/mineral interactions
DE: 1011 Thermodynamics (0766, 3611, 8411)
DE: 1831 Groundwater quality
SC: Biogeosciences [B]
MN: 2007 Fall Meeting