Groundwater Arsenic and Iron Contamination in the Gangetic Plains of India: Safe Drinking Water Option on Quaternary Stratigraphy

Abstract

AbstractLate Quaternary stratigraphy, geomorphology, and sedimentation in the entrenched channels and floodplains of the upper, middle, and lower Ganga plains in the states of Uttar Pradesh, Bihar, Jharkhand, and West Bengal have control on groundwater arsenic contamination. Arsenic analysis was done through atomic absorption spectrometry, and Iron was analyzed by the use of UV spectro-photometer. Arsenic contamination in groundwater above 50 µg/L is reported in Unnao and Allahabad districts in the upper Ganga plain. In the middle Ganga plain, 66% of tubewells from Buxar, Ghazipur, Varanasi, and Mirzapur districts and 89% of tubewells from Vaishali, Patna, Bhojpur, and Ballia districts have arsenic > 10 µg/L (WHO guideline). Most of the arsenic-affected villages are located close to abandoned or present meander channels of the Ganga River. In contrast, tubewells located in Kanpur, Allahabad, Mirzapur, Chunar, Varanasi, Saidpur, Ghazipur, Muhammadabad, Ballia, Buxar, Ara, Chhapra, Patna, and Hazipur towns are arsenic-safe in groundwater because of their positions on the Pleistocene Older Alluvium upland surfaces. In the middle Ganga plain, 77% of tubewells are located in shallow depth (21–40 m). About 40% of tubewells have arsenic > 50 µg/L within the depth of 17–50 m. The iron content in tubewell water samples varies from 0.1 to 13 mg/L. In the lower Ganga plain, arsenic contaminated aquifers (arsenic >10 μg/L) are confined in the Holocene entrenched channels and floodplains of the Bhagirathi River.KeywordsArsenicTubewell waterNewer alluviumOlder alluviumFluvial geomorphology