Speciation of As in the blackfoot disease endemic area.

Speciation of arsenic (As) in well water and contaminated soil in the blackfoot disease endemic area has been studied by extended X-ray absorption fine structural (EXAFS) spectroscopy in the present work. Experimentally, we found that arsenic in the well water possessed an As-O bond distance of 1.72 A with a coordination number (CN) of 4.3. In the blackfoot disease area, arsenic with a high oxidation state (As(V)) was also observed in the contaminated soil. In the early stage (after 90 minutes) of the electrokinetic remediation (EKR) of the contaminated soil, the in-situ EXAFS data indicated that the CN of As-O (1st shell) decreased slightly, that may be due to the perturbation of the incompact As atoms in the outer shells by EKR.