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BIOACCESSIBILITY OF ARSENIC( V )BOUND TO FERRIHYDRITE USING A SIMULATED GASTROINTESTINAL SYSTEM
Citation:
BEAK, D. G., N. T. BASTA, K. G. SCHECKEL, AND S. J. TRAINA. BIOACCESSIBILITY OF ARSENIC( V )BOUND TO FERRIHYDRITE USING A SIMULATED GASTROINTESTINAL SYSTEM. J. Schnoor (ed.), ENVIRONMENTAL SCIENCE AND TECHNOLOGY. John Wiley & Sons, Ltd., Indianapolis, IN, 40(4):1364-1370, (2006).
Description:
The risk posed from incidental ingestion of arsenic-contaminated soil may depend on sorption of arsenate (As(V)) to oxide surfaces in soil. Arsenate sorbed to ferrihdrite, a model soil mineral, was used to simulate possible effects on ingestion of soil contaminated with As(V) sorbed to Fe oxide surfaces. Arsenate sorbed to ferrihydrite was placed in a simulated gastrointestinal tract (in vitro) to, ascertain the bioaccessibility of As(V) and changes in As(V) surface speciation caused by the gastrointestinal system. The speciation of As was determined using Extended X-ray Absorption Fine Structure (EXAFS) analysis and X-ray Absorption Near Edge Spectroscopy (XANES). The As(V)adsorption maximum was found to be 93 mmol kg-I. The bioaccessible As(V) ranged form a to 5% and surface speciation was determined to be mononuclear monodentate, mononuclear bidentate, and binuclear bidentate. Arsenate concentration in the intestine was not constant and varied form 0.001 to 0.53 mM for the highest As(V) treated sample. These results suggest that the bioaccessibility of As(V) is related to the As(V) concentration, the As(V) adsorption maximum, and that multiple measurements of dissolved As(V) in the intestinal phase are needed to calculate the bioaccessibility of As(V) adsorbed to ferrihydrite.