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Title: Enhanced and stabilized arsenic retention in microcosms through the microbial oxidation of ferrous iron by nitrate

Magnetite strongly retains As, and is relatively stable under Fe(III)-reducing conditions common in aquifers that release As. In this paper, laboratory microcosm experiments were conducted to investigate a potential As remediation method involving magnetite formation, using groundwater and sediments from the Vineland Superfund site. The microcosms were amended with various combinations of nitrate, Fe(II) (aq) (as ferrous sulfate) and lactate, and were incubated for more than 5 weeks. In the microcosms enriched with 10 mM nitrate and 5 mM Fe(II) (aq), black magnetic particles were produced, and As removal from solution was observed even under sustained Fe(III) reduction stimulated by the addition of 10 mM lactate. The enhanced As retention was mainly attributed to co-precipitation within magnetite and adsorption on a mixture of magnetite and ferrihydrite. Sequential chemical extraction, X-ray absorption spectroscopy and magnetic susceptibility measurements showed that these minerals formed at pH 6–7 following nitrate-Fe(II) addition, and As-bearing magnetite was stable under reducing conditions. Scanning electron microscopy and X-ray diffraction indicated that nano-particulate magnetite was produced as coatings on fine sediments, and no aging effect was detected on morphology over the course of incubation. Finally, these results suggest that a magnetite based strategy may be a long-term remedial optionmore » for As-contaminated aquifers.« less
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5] ;  [2] ; ORCiD logo [2]
  1. Columbia Univ., New York, NY (United States); Lamont-Doherty Earth Observatory, Palisades, NY (United States)
  2. Lamont-Doherty Earth Observatory, Palisades, NY (United States)
  3. Barnard College, New York, NY (United States)
  4. Lamont-Doherty Earth Observatory, Palisades, NY (United States); Barnard College, New York, NY (United States)
  5. Miami Univ., Oxford, OH (United States)
Publication Date:
Grant/Contract Number:
ES010349; ES009089; 2007-03128
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 144; Journal ID: ISSN 0045-6535
Research Org:
Columbia Univ., Palisades, NY (United States). Lamont-Doherty Earth Observatory
Sponsoring Org:
USDOE; Dept. of Agriculture (USDA) (United States); National Inst. of Health (NIH) (United States)
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 54 ENVIRONMENTAL SCIENCES; magnetite; iron minerals; arsenic concentration; redox transformation; microcosm experiment; immobilization
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1358938