Synchrotron-based X-ray absorption spectroscopy (XAS), specifically X-ray absorption near edge structure (XANES) spectroscopy, indicated the dominant species of As in soil and sediment samples was arsenate [As(V)], which is similar to the chemical form of As in the groundwaters of this region. No evidence of arsenite [As(III)] was identified in any of the solid-phase samples, including earthworm castings. |