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Title: Sulfide-Driven Arsenic Mobilization from Arsenopyrite and Black Shale Pyrite

Abstract

We examined the hypothesis that sulfide drives arsenic mobilization from pyritic black shale by a sulfide-arsenide exchange and oxidation reaction in which sulfide replaces arsenic in arsenopyrite forming pyrite, and arsenide (As-1) is concurrently oxidized to soluble arsenite (As+3). This hypothesis was tested in a series of sulfide-arsenide exchange experiments with arsenopyrite (FeAsS), homogenized black shale from the Newark Basin (Lockatong formation), and pyrite isolated from Newark Basin black shale incubated under oxic (21% O2), hypoxic (2% O2, 98% N2), and anoxic (5% H2, 95% N2) conditions. The oxidation state of arsenic in Newark Basin black shale pyrite was determined using X-ray absorption-near edge structure spectroscopy (XANES). Incubation results show that sulfide (1 mM initial concentration) increases arsenic mobilization to the dissolved phase from all three solids under oxic and hypoxic, but not anoxic conditions. Indeed under oxic and hypoxic conditions, the presence of sulfide resulted in the mobilization in 48 h of 13-16 times more arsenic from arsenopyrite and 6-11 times more arsenic from isolated black shale pyrite than in sulfide-free controls. XANES results show that arsenic in Newark Basin black shale pyrite has the same oxidation state as that in FeAsS (-1) and thus extend the sulfide-arsenide exchangemore » mechanism of arsenic mobilization to sedimentary rock, black shale pyrite. Biologically active incubations of whole black shale and its resident microorganisms under sulfate reducing conditions resulted in sevenfold higher mobilization of soluble arsenic than sterile controls. Taken together, our results indicate that sulfide-driven arsenic mobilization would be most important under conditions of redox disequilibrium, such as when sulfate-reducing bacteria release sulfide into oxic groundwater, and that microbial sulfide production is expected to enhance arsenic mobilization in sedimentary rock aquifers with major pyrite-bearing, black shale formations.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
980583
Report Number(s):
BNL-93501-2010-JA
Journal ID: ISSN 0016-7037; GCACAK; TRN: US201015%%1968
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Geochimica et Cosmochimica Acta
Additional Journal Information:
Journal Volume: 72; Journal ID: ISSN 0016-7037
Country of Publication:
United States
Language:
English
Subject:
04 OIL SHALES AND TAR SANDS; AQUIFERS; ARSENIC; ARSENIDES; BLACK SHALES; HYPOTHESIS; INCUBATION; MICROORGANISMS; OXIDATION; PRODUCTION; PYRITE; SEDIMENTARY ROCKS; SOLIDS; SPECTROSCOPY; SULFATE-REDUCING BACTERIA; SULFATES; SULFIDES; VALENCE; national synchrotron light source

Citation Formats

Zhu, W., Young, L, Yee, N, Serfes, M, Rhine, E, and Reinfelder, J. Sulfide-Driven Arsenic Mobilization from Arsenopyrite and Black Shale Pyrite. United States: N. p., 2008. Web. doi:10.1016/j.gca.2008.08.006.
Zhu, W., Young, L, Yee, N, Serfes, M, Rhine, E, & Reinfelder, J. Sulfide-Driven Arsenic Mobilization from Arsenopyrite and Black Shale Pyrite. United States. doi:10.1016/j.gca.2008.08.006.
Zhu, W., Young, L, Yee, N, Serfes, M, Rhine, E, and Reinfelder, J. Tue . "Sulfide-Driven Arsenic Mobilization from Arsenopyrite and Black Shale Pyrite". United States. doi:10.1016/j.gca.2008.08.006.
@article{osti_980583,
title = {Sulfide-Driven Arsenic Mobilization from Arsenopyrite and Black Shale Pyrite},
author = {Zhu, W. and Young, L and Yee, N and Serfes, M and Rhine, E and Reinfelder, J},
abstractNote = {We examined the hypothesis that sulfide drives arsenic mobilization from pyritic black shale by a sulfide-arsenide exchange and oxidation reaction in which sulfide replaces arsenic in arsenopyrite forming pyrite, and arsenide (As-1) is concurrently oxidized to soluble arsenite (As+3). This hypothesis was tested in a series of sulfide-arsenide exchange experiments with arsenopyrite (FeAsS), homogenized black shale from the Newark Basin (Lockatong formation), and pyrite isolated from Newark Basin black shale incubated under oxic (21% O2), hypoxic (2% O2, 98% N2), and anoxic (5% H2, 95% N2) conditions. The oxidation state of arsenic in Newark Basin black shale pyrite was determined using X-ray absorption-near edge structure spectroscopy (XANES). Incubation results show that sulfide (1 mM initial concentration) increases arsenic mobilization to the dissolved phase from all three solids under oxic and hypoxic, but not anoxic conditions. Indeed under oxic and hypoxic conditions, the presence of sulfide resulted in the mobilization in 48 h of 13-16 times more arsenic from arsenopyrite and 6-11 times more arsenic from isolated black shale pyrite than in sulfide-free controls. XANES results show that arsenic in Newark Basin black shale pyrite has the same oxidation state as that in FeAsS (-1) and thus extend the sulfide-arsenide exchange mechanism of arsenic mobilization to sedimentary rock, black shale pyrite. Biologically active incubations of whole black shale and its resident microorganisms under sulfate reducing conditions resulted in sevenfold higher mobilization of soluble arsenic than sterile controls. Taken together, our results indicate that sulfide-driven arsenic mobilization would be most important under conditions of redox disequilibrium, such as when sulfate-reducing bacteria release sulfide into oxic groundwater, and that microbial sulfide production is expected to enhance arsenic mobilization in sedimentary rock aquifers with major pyrite-bearing, black shale formations.},
doi = {10.1016/j.gca.2008.08.006},
journal = {Geochimica et Cosmochimica Acta},
issn = {0016-7037},
number = ,
volume = 72,
place = {United States},
year = {2008},
month = {1}
}