EPA Science Inventory

Examination of Arsenic Speciation in Sulfidic Solutions Using X-ray Absorption Spectroscopy

Citation:

BEAK, D. G., R. T. WILKIN, R. FORD, AND S. D. KELLY. Examination of Arsenic Speciation in Sulfidic Solutions Using X-ray Absorption Spectroscopy. DOI: 10.1021/es07185 J. Schnoor (ed.), ENVIRONMENTAL SCIENCE AND TECHNOLOGY. American Chemical Society, Washington, DC, 42(5):1643-1650, (2008).

Description:

The chemical speciation of arsenic in sulfidic waters is complicated by the existence of thioarsenic species. The purpose of this research was to use advanced spectroscopy techniques along with speciation modeling and chromatography to elucidate the chemical speciation of As in sulfidic solutions. Results of the X-ray absorption spectroscopy (XAS) and modeling show that experimental solutions contain a mixture of arsenites and thioarsenites with increasing substitution of S for O on As with increasing sulfide concentration. There was no evidence of polymeric As species, or transformation of thioarsenites to thioarsenates as suggested in the literature. Additionally the As speciation measured using XAS was consistent with a thermodynamic model for arsenic speciation in sulfidic systems. Our data cast doubt on the existence of thioarsenates in natural waters as have been postulated through chromatographic techniques. Instead the same chromatographic peak positions proposed for thioarsenates can be explained by thioarsenite species. Additionally sample dilution was shown to change species distribution and care should be taken to avoid sample dilution prior to chromatographic analysis.

Purpose/Objective:

publish information in a journal article

URLs/Downloads:

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Record Details:

Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Start Date: 03/01/2008
Completion Date: 03/01/2008
Record Last Revised: 02/12/2014
Record Created: 04/09/2007
Record Released: 04/09/2007
OMB Category: Other
Record ID: 167305

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL RISK MANAGEMENT RESEARCH LABORATORY

GROUND WATER AND ECOSYSTEMS RESTORATION DIVISION

SUBSURFACE REMEDIATION BRANCH