ENVR 33 |
| Here we present geographic information system (GIS) based model that can be used to predict arsenic concentrations in groundwater by using state-of-the-art statistical procedures. Using these models we have constructed probability maps of contaminated regions exceeding WHO guide line of 10 μg L-1 in southeast Asia. Arsenic is widely distributed in nature and can be introduced into groundwater through a combination of natural processes and/or anthropogenic activities. Regardless of the source of arsenic, its solubility is mostly controlled by the chemical conditions (pH and Eh) of the groundwater. Two important aquifer conditions lead to arsenic mobilization through desorption and dissolution. These conditions take place under two process regimes: first, highly reducing aquifers where arsenic is present in its more soluble reduced state and second, aquifers with high pH conditions where arsenic is soluble in its oxidized state. In the absence of detailed geochemical information, readily available GIS parameters that represent both geological properties and environmental factors such as climate, drainage condition and topography are used for modeling. Since the initial discovery of the problem in the Bengal delta, intensive sampling programs have been carried out in several regions including Bangladesh, Vietnam and Cambodia However we do not yet know that we have been able to identify all potentially problematic areas. These maps identify both the known areas and highlight areas in southeast Asia that need to be further investigated. |
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Symposium Honoring Dr. Walter Giger
8:30 AM-12:15 PM, Monday, August 20, 2007 Boston Park Plaza -- Stanbro Rm, Oral
Division of Environmental Chemistry |