Hydrochemistry of Arsenic-Enriched Aquifer from Rural West Bengal, India: A Study of the Arsenic Exposure and Mitigation Option

Abstract

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 −37 mV; mean, −68 mV) and nitrate (range, 0.01-1.7 mg/l; mean, 0.14 mg/l) followed by high alkalinity (range, 100-630 mg/l; mean, 301 mg/l), Fe (range, 0.99-38 mg/l; mean, 8.1 mg/l), phosphate (range, 0.01-15 mg/l; mean, 0.54 mg/l), hardness (range, 46-600 mg/l; mean, 245 mg/l) and sulphate (range, 0.19-88 mg/l; mean, 7.2 mg/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, 269 μg/l) and Fe (mean, 9.8 mg/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.

Arsenic contamination in groundwater and its possible sources in Hanam, Vietnam

“…Similar levels of As in groundwater (159 μg l −1 in average) were reported from the Hanoi area, where 72% of the tube wells contained As levels higher than 10 μg l −1 (Berg et al 2001). Comparable levels of As contamination were observed in Bangladesh, India, and Taiwan (Chowdhury et al 2000;Nath et al 2008;Wang et al 2007). We detected much lower As levels in the groundwater at sites close to the Red River than at sites located on the banks of the Chau Giang River; this has also been observed by .…”

“…On the other hand, compared to the data obtained in this study, higher levels of sulfate and slightly lower Fe concentrations in the groundwater were reported from the Mekong Delta, southern Vietnam, where acid, sulfaterich soils are abundant (Nguyen and Itoi 2009). Moreover, the chemical features of the groundwater observed in the present study are quite similar to those in Bangladesh and West Bengal, India (Nickson et al 2000;Anawar et al 2003;Nath et al 2008). Occurrence of As in aquifer sediments…”

Natural Arsenic in Global Groundwaters: Distribution and Geochemical Triggers for Mobilization

“…Biswas et al [151] also reported lower As concentrations in hair and nail samples from children compared with adults in the Samta village of Bangladesh. Nath et al [152] reported similar findings in their study population of Baruipur, South 24 Parganas district, West Bengal. Medical screening in the Bangladesh region [153] showed that most of the study populations were affected by keratosis and melanosis, whereas a few subjects were affected by chronic bronchitis and whole-body infection.…”

A Review of Groundwater Arsenic in the Bengal Basin, Bangladesh and India: from Source to Sink

“…Several workers have reported methane in the aquifers from many parts of the basin [38,122]. The bicarbonate may also be supplied from local biogeochemical processes to the groundwater system [123,124]. Several workers reported strong to moderate correlation between arsenic and iron which indicates the release of arsenic due to dissolution of and desorption from iron hydroxides in the sediments [117,120].…”