Arsenic in Groundwaters of the Ganges, Mekong, and Red River Basins

The use of hazardous, arsenic-bearing groundwater for drinking, cooking, and irrigation has led in Bangladesh to what has been described by a leading epidemiologist as the worst mass poisoning of a human population in history (Smith et al. 2000). While surface waters usually have a very low dissolved arsenic content, the widespread occurrence of hazardous pathogens in rivers and ponds prompted national and international agencies to turn to groundwater resources for both irrigation and drinking water. While mega-cities, such as Kolkata, can handle the high arsenic content in groundwater because of centralized adduction systems and treatment plants, small villages, where as many as 10 million new domestic wells may have been drilled in the last 40 years, face an enormous problem because the efficiency of water treatment is hard to control for such a large number of wells, and also because arsenic hotspots are extremely patchy. As a result of this usage, over 100,000 people in Bangladesh have already developed skin lesions. Millions of people are at risk of developing debilitating illnesses, including cancers, and excess deaths of the order of several thousand per year might be anticipated in the absence of effective remediation strategies (Yu et al. 2003). There is an extensive literature on the distribution and origin of arsenic in shallow groundwaters in Bangladesh (BGS, DPHE 2001; Chakraborti 2001; Harvey et al. 2005), on arsenic uptake by rice (Williams et al. 2005) and other foods (Al Rmalli et al. 2005), on human health impacts and regulatory issues (Smith and Smith 2004), and on remediation strategies (van Geen et al. 2003; Kanel et al. 2005).