Geochemical and mineralogical contrasts between low and very high arsenic affected areas in Murshidabad district, West Bengal, India

摘要

The principal vector responsible for arsenic (As) poisoning in human populations is consumption of drinking water, chiefly from groundwater sources. Such poisoning currently affects as many as 60 million people in the Ganges delta of Bangladesh and West Bengal, India, resulting in what may be the worst example of environmental poisoning in human history (van Geen et al., 2008; McArthur et al., 2004; Smedley et al., 2002; Nickson et al., 2000). This study addresses one of the worst affected districts (Murshidabad) of West Bengal, India (some seminal and previous work done in that area includes Chat-terjee et al., 1996; Pal et al., 2002; Stuben et al., 2003; Acharyya et al., 2007; Charlet et al., 2007; Nath et al., 2009; Bhattacharyya et al., 2009). Arsenic levels significantly greater (～30×) than the WHO and USEPA recommend levels of 10 μg/L have been observed in tubewell waters in the blocks east of the river Bhagi-rathi, compared to the west of Bhagirathi, within the district of Murshidabad. Hydrogeochemical and mineralogical studies are ongoing in five blocks in Murshidabad:four east of Bhagirathi (Beldanga (BM), Hariharpara (HK), Jalangi (JB), Naoda (NR), and one west of Bhagirathi [Nabagram (NB)]. The river Bhagirathi is running N-S as a tributary of river Ganges. A 40 km transect with one control site and 4 high to very high concentrated sites are targeted in this study. The source of As is thought to be geogenic, originating in As-rich Ethologies of the headwaters region of the river Ganges,transported by the Ganges as it flows down from the Himalayas forming its floodplain throughout the entire district of Murshidabad (Mukherjee et al., 2008, 2009).