Environmental studies of arsenic and antimony species in a Blackfoot disease area and near a chemical reprocessing plant

The toxicity and bioavailability of arsenic and antimony in the environment depend on their species. Two case studies concerning the effects of arsenic and antimony species in the environment will be discussed in this study. The first case concerns the distribution of arsenic species in the ground water of the Blackfoot disease (BFD) area in Taiwan. BFD is a peripheral vascular disease found in a limited area on the southwest coast of Taiwan. The ground waters in the BFD area contain high concentrations of arsenic with {dollar}rm Assp{lcub}3+{rcub}.{dollar} On the average, {dollar}rm 671 pm 149 mu g/L{dollar} of total dissolved arsenic was measured; the predominant arsenic species in the well waters of the BFD is {dollar}rm Assp{lcub}3+{rcub}{dollar} with an average {dollar}rm Assp{lcub}3+{rcub}/Assp{lcub}5+{rcub}{dollar} ratio of 2.6. Ultrafiltration experiments indicate that the dissolved arsenic species can be roughly divided into two groups, one with molecular weight {dollar}<{dollar}1000 Da (81%), and the other with molecular weight {dollar}>{dollar}300,000 Da (11%). The significance of this arsenic speciation study to our understanding of BFD will be discussed. The second case is related to an environmental study of the fission product {dollar}sp{lcub}125{rcub}{dollar}Sb (half-life 2.7 years) around the Idaho chemical processing plant (ICPP) at the Idaho National Engineering Laboratory (INEL). Data on the distribution and migration of {dollar}sp{lcub}125{rcub}{dollar}Sb in the desert environment around ICPP are discussed. The highest radioactivity of {dollar}sp{lcub}125{rcub}{dollar}Sb is in the sagebrush leaves. Its radioactivity in the soil is in inverse proportion to the depth of soil, and the migration speed downward to the water table is quite slow so as not to affect the environment in that area. About 30% of {dollar}sp{lcub}125{rcub}{dollar}Sb could be leached from sagebrush leaves, and less than 2% is trivalent antimony. An ion-exchange chromatography method using AG 50W-X8 cation resin and AG 1-X8 anion resin in the same column, with the anion resin packed at the bottom, is developed for simultaneous separation of arsenic and antimony species {dollar}rm(Assp{lcub}3+{rcub}, Assp{lcub}5+{rcub}, Sbsp{lcub}3+{rcub}, and Sbsp{lcub}5+{rcub}){dollar} in aqueous samples. The detection limit is in the ppb level.