Arsenic contamination in groundwater, sediment and soil in Araihazar, Bangladesh

Arsenic (As) contamination is a severe public health issue for decades. About 150 million people from 70 countries in the world are at risk to health hazards associated with As. Long term exposure to As can cause serious human health issues to both children and adults. Especially, As poisoning is the most threatening to the South and Southeast Asian countries compared to the rest of the world. In Bangladesh, the most severely affected country from As contamination, about 30-35 million people are exposed to elevated (>50 μg L⁻¹ As concentrations in groundwater. Anthropogenic intervention or groundwater pumping has made this scenario even worse. In Bangladesh, As contaminated groundwater is heavily used for drinking as well as irrigation purposes. Therefore, As exposure increases with groundwater irrigation, soil loading of As from groundwater and transfer of As from soil to plants and crops. Irrigation with contaminated groundwater gradually accumulates As in agricultural soil, which causes toxicity to crops, reduces crop yield and threatens sustainable agriculture. Researchers have warned that only a few decades of irrigation pumping will exceed the high end of As level in soil. Araihazar Upazila, Bangladesh, is located about 25 km from the capital city Dhaka, and has an aerial extent of 183 km2 with a varied groundwater As concentration from 0.1 to 864 μg L⁻¹. Up to date, a significant number of studies have been conducted in Araihazar, to characterize hydrogeological and geochemical factors, mobilization, and spatial distribution of As in water, aquifer sediments and soil. In this study, we compiled As concentration data from water wells, sediments, and soils in Araihazar that were collected from the public sources and government agencies. We summarized all these data to give an overview of the As contamination scenario in this severely affected area of Bangladesh. The knowledge from this study will increase our understanding of pollution control, provide support for contamination management and help planners and managers in the local government and regulatory authorities to assess, plan, respond and implement new and existing policies. In addition, the results from this study can also be applicable to other areas in Bangladesh and other South and Southeast Asian countries where groundwater As contamination is a major threat.