Arsenic mobilization in shallow alluvial aquifers of Chapai-Nawabganj District, Northwestern Bangladesh

摘要

Arsenic (As) contamination has recently been recognized as crucial environmental problems facing many countries in the world including Bangladesh, India, Nepal, Thailand, China, Taiwan, Vietnam, Chile, Hungary, and parts of the USA (Smedley & Kinniburgh, 2002). Most of the environmental problem is associated with As are the results of mobilization under natural conditions. The process of As mobilization in alluvial sediments is complex; it may occur as Fe and Mn oxides are reductively dissolved by Fe(Ⅲ)-reducmg bacteria under moderately reducing conditions (e.g., Polizzotto et al., 2008). Alternatively, As may be mobilized by ionic competition of other ions (e.g., nitrate, carbonate, and silicate) on sorbing sites of oxides (Lee et al., 2005). The main objectives of this study are to elucidate the distribution, occurrence and mobilization of As in shallow alluvial aquifers of Chapai-Nawabganj District.