摘要：

The present study aims to understand the hydrochemistry vis-à-vis As-exposure from drinking groundwater in rural Bengal. The characteristic feature of the groundwaters are low Eh (range, 151 to 37mV; mean, 68mV) and nitrate (range, 0.01–1.7mg/l; mean, 0.14mg/l) followed by high alkalinity (range, 100–630mg/l; mean, 301mg/l), Fe (range, 0.99–38mg/l; mean, 8.1mg/l), phosphate (range, 0.01–15mg/l; mean, 0.54mg/l), hardness (range, 46–600mg/l; mean, 245mg/l) and sulphate (range, 0.19–88mg/l; mean, 7.2mg/l), indicating reducing nature of the aquifer. The land use pattern (sanitation, surface water bodies, sanitation coupled with surface water bodies and agricultural lands) demonstrates local enrichment factor for As/Fe in groundwater. Among these, sanitation is the most prevailing where groundwater is generally enriched with As (mean, 269μg/l) and Fe (mean, 9.8mg/l). Questionnaire survey highlights that 70% of the villagers in the study area do not have proper sanitation. This demonstrating the local unsewered sanitation (organic waste, anthropogenic in origin) could also cause As toxicity in rural Bengal. In the agricultural lands, higher mean values of alkalinity, phosphate, sulphate, hardness and electrical conductivity was observed, and could be linked with the excessive use of fertilizers for agricultural production. Bio-markers study indicates that the accumulation of As in hair and nail is related with the construction of exposure scenario with time dimension. The strength and weakness of the on-going West Bengal and Bangladesh drinking water supply scenario and achievability towards alternative options are also evaluated.

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