Correlating Arsenic (As) and Iron (Fe) Speciation to As Bioavailability from a Collection of Contaminated Soils with Varying Contamination Sources and Soil Properties.

Arsenic (As) in contaminated topsoil poses a human health risk partially from incidental ingestion of airborne dust. Animal feeding studies are used to quantify the fraction of total As that enters systemic circulation from ingested soil dust, defined as the soil’s oral bioavailability. Arsenic bioavailability from the contaminated soil should be dependent on the solubility of As-containing minerals and the solubilities of As-adsorbing surfaces in soil. The objective of the study was to identify As species in a series of soils with different contamination sources and soil conditions and correlate them with As bioavailability. The soils used in this study were fed to either mice or juvenile swine for bioavailability measurement. Synchrotron-based x-ray absorption spectroscopy (XAS) was used for As and Fe speciation in the fed soils and Fe Mossbauer to corroborate the XAS speciation. Significant trends were identified between As bioavailability and As species and Fe species by multivariate analysis. The results will indicate whether certain As species correspond to higher bioavailability and present a higher risk via soil dust ingestion.