title: Comparison of antimony behavior with that of arsenic under various soil redox conditions.
abstract: The oxidation states and host phases of Sb and As in soil samples of mine tailing (Ichinokawa mine, Ehime, Japan) and in laboratory soil-water systems were determined by X-ray absorption fine structure (XAFS) spectroscopy. HPLC-ICP-MS was used for speciation of Sb and As in soil water. In the Ichinokawa soil water system, Sb was present exclusively as the oxidized form, Sb(V), over a wide redox range (from Eh = 360 to -140 mV, pH 8), while As was present as a mixture of As(III) and As(V). This finding was confirmed in the laboratory experiments. These results suggest that Sb(V) is a very stable form in the environment and that Sb is oxidized at more negative Eh than As. Combining the results of Fe and Mn XAFS analyses and a positive correlation among Sb, As, and Fe abundances in the soil, the host phases of Sb and As in soil were Fe(III) hydroxide. XAFS analyses of Sb and As are also consistent with this finding. Under reducing conditions, the concentration of As in the soil water increased whereas that of Sb decreased in both the Ichinokawa and laboratory systems. This suggests that this contrasting behavior is controlled mainly by the different redox properties of Sb and As.
authors.affiliation: Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan. mitsunobu@hiroshima-u.ac.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mitsunobu
authors.forename: Teppei
authors.initials: T
authors.lastname: Harada
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takahashi
mesh_terms: D000965:Antimony / Q000737:chemistry*; D001151:Arsenic / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D007501:Iron / Q000737:chemistry; D007564:Japan; D013058:Mass Spectrometry; D008906:Mining; D010084:Oxidation-Reduction; D012987:Soil / Q000032:analysis*; D014965:X-Rays
chemical_list: D012987:Soil; D000965:Antimony; D007501:Iron; D001151:Arsenic