摘要：The arsenic contamination of groundwater in Uttar Pradesh State was first recognized in 2003 and is now seen at 20 Districts out of 70 Districts. University of Miyazaki has performed the arsenic mitigation project in Bahraich District, severest arsenic-affected one in the 20 Districts, from June 2008 until now, with JICA (Japan International Cooperation Agency). The integrated mitigation, such as the raising awareness of villager, installing of alternative water supply units and healthcare of arsenocosis patients, have been executed at the 2 villages. The symptom of the arsenocosis patients was not so severe, which will be, therefore, improved by drinking arsenic-safe water supplied through arsenic removal units, installed by this project. In this paper, following results is discussed for the situation and mechanism of arsenic contamination of groundwater, objected in connection with the installation of arsenic removal units: 1) Groundwater is almost contaminated with arsenic in deep tubewell (depth: about 30 m), but scarcely in shallow tubewell (depth: about 10 m); 2) Arsenic contaminated groundwater is under the reduced condition with the oxidized condition for no-arsenic contaminated groundwater; 3) Arsenic concentration shows almost linear correlation with concentrations of Fe2+ and -N; 4) Ground is composed of sand with high arsenic content at around 25 m depth; 5) Arsenic exists mainly in the phase of reducible fraction or weak acid soluble fraction but no oxidizable fraction in the ground.
