Bioavailable and Bioaccessible Pools of Soil Bound as: Results From Extraction Methods, X-Ray Absorption Spectroscopy, and in-Vivo Feeding Studies.

Arsenic has been identified as a carcinogen responsible for gastrointestinal, cardiovascular, and reproductive illnesses.  Identifying the level of soil As contamination at which public health is threatened requires an understanding of As behavior in soils and site-specific factors.  Arsenic bioavailability and the pool of bioaccessible As is affected by the soil environment, the redox state of As, and its' coordinating environment.  We analyzed a variety of soils with different anthropogenic sources of As.  This study examined apple orchard and sugarcane soils sprayed with arsenical insecticides, mine soils, arsenic sorbed to ferrihydrite, and a reference soil NIST 2710a.  We will present results from standard soil analyses including nitric acid digest, selective dissolution studies (citrate-dithionite-bicarbonate and acid ammonium oxalate), and X-ray absorption spectroscopy.  These data combined with results from in-vitro extractions along with swine and mouse As bioavailability studies will be used to help confirm the pool of bioavailable As at each site.  Results from this study paired with site-specific soil conditions may help predict As relative bioaccessiblity at other contaminated locations.