title: Effect of oxalic acid treatment on sediment arsenic concentrations and lability under reducing conditions.
abstract: Oxalic acid enhances arsenic (As) mobilization by dissolving As host minerals and competing for sorption sites. Oxalic acid amendments thus could potentially improve the efficiency of widely used pump-and-treat (P&T) remediation. This study investigates the effectiveness of oxalic acid on As mobilization from contaminated sediments with different As input sources and redox conditions, and examines whether residual sediment As after oxalic acid treatment can still be reductively mobilized. Batch extraction, column, and microcosm experiments were performed in the laboratory using sediments from the Dover Municipal Landfill and the Vineland Chemical Company Superfund sites. Oxalic acid mobilized As from both Dover and Vineland sediments, although the efficiency rates were different. The residual As in both Dover and Vineland sediments after oxalic acid treatment was less vulnerable to microbial reduction than before the treatment. Oxalic acid could thus improve the efficiency of P&T. X-ray absorption spectroscopy analysis indicated that the Vineland sediment samples still contained reactive Fe(III) minerals after oxalic acid treatment, and thus released more As into solution under reducing conditions than the treated Dover samples. Therefore, the efficacy of enhanced P&T must consider sediment Fe mineralogy when evaluating its overall potential for remediating groundwater As.
authors.affiliation: Department of Earth and Environmental Sciences, Columbia University, Mail Code 5505, New York, NY 10027, USA; Lamont-Doherty Earth Observatory, PO Box 1000, 61 Route 9W, Palisades, NY 10964, USA. Electronic address: jingsun@LDEO.columbia.edu.
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.affiliation: Lamont-Doherty Earth Observatory, PO Box 1000, 61 Route 9W, Palisades, NY 10964, USA.
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Bostick
authors.affiliation: Department of Environmental Sciences, Barnard College, 3009 Broadway, New York, NY 10027, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Mailloux
authors.affiliation: Lamont-Doherty Earth Observatory, PO Box 1000, 61 Route 9W, Palisades, NY 10964, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Ross
authors.affiliation: Lamont-Doherty Earth Observatory, PO Box 1000, 61 Route 9W, Palisades, NY 10964, USA.
authors.forename: Steven N
authors.initials: SN
authors.lastname: Chillrud
mesh_terms: D001151:Arsenic / Q000032:analysis / Q000737:chemistry*; D052918:Environmental Restoration and Remediation; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry*; D060587:Groundwater / Q000032:analysis / Q000737:chemistry*; D064371:Hazardous Waste Sites; D058085:Iron Compounds / Q000737:chemistry; D009513:New Hampshire; D009515:New Jersey; D019815:Oxalic Acid / Q000032:analysis / Q000737:chemistry*; D010084:Oxidation-Reduction; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D058085:Iron Compounds; D014874:Water Pollutants, Chemical; D019815:Oxalic Acid; D001151:Arsenic
keywords: Arsenic contamination; Iron mineralogy; Microbial reduction; Oxalic acid; Pump-and-treat