Adsorption, oxidation, and bioaccessibility of As(III) in soils.

At As-contaminated sites, where the ingestion of soil by children is typically the critical human-health exposure pathway, information on the bioavailability of soil-bound As is often limited. The influence of various soil physical and chemical properties (iron and manganese oxides, pH, cation exchange capacity, total inorganic and organic carbon, and particle size) on As(III) adsorption, sequestration, bioaccessibility (as a surrogate for oral bioavailability), and oxidation was investigated in 36 well-characterized soils by use of a physiologically based extraction test (PBET). These results were compared to an earlier published study with As(V) on the same set of soils.

Chemical structure of arsenic and chromium in CCA-treated wood: implications of environmental weathering.

Chromated copper arsenate (CCA) has been used to treat lumber for over 60 years to increase the expected lifetime of CCA-treated wood. Because of the toxicity of the arsenic and chromium used in CCA treatment, regulatory and public attention has become focused on the potential risks from this exposure source. In particular, exposure of children to arsenic from CCA-treated wood used in decks and play sets has received considerable attention.

Arsenic(III) oxidation and arsenic(V) adsorption reactions on synthetic birnessite.

The oxidation of arsenite (As(III)) by manganese oxide is an important reaction in both the natural cycling of As and the development of remediation technology for lowering the concentration of dissolved As(III) in drinking water. This study used both a conventional stirred reaction apparatus and extended X-ray absorption fine structure (EXAFS) spectroscopy to investigate the reactions of As(III) and As(V) with synthetic birnessite (MnO2). Stirred reactor experiments indicate that As(III) is oxidized by MnO2 followed by the adsorption of the As(V) reaction product on the MnO2 solid phase.