6. Arsenic Contamination of Groundwater in Barak Valley, Assam, India: Topography-Based Analysis and Risk Assessment

Arsenic (As) contamination of groundwater is a major environmental and public health issue in the Ganga-Brahmaputra-Meghna (GBM) plains, including almost all states in the Ganga basin, large areas of Bangladesh (GBM basin), and some districts of Assam (Brahmaputra and Meghna sub-basins of the GBM basin) in North East India (Chowdhury UK, Biswas BK, Chowdhury TR, Samanta G, Mandal BK, Basu GC, Chanda CR, Lodh D, Saha KC, Mukherjee SK, Roy S, Kabir S, Quamruzzaman Q, Chakraborti D, Environ Health Perspect 108(5):393–397, 2000; Chakraborti D, Mukherjee SC, Pati S, Sengupta MK, Rahman MM, Chowdhury UK, Lodh D, Chanda CR, Chakraborti AK, Basu GK, Environ Health Perspect 111(9):1194–1201, 2003; Singh AK, Arsenic contamination in groundwater of North Eastern India. In: Proceedings of national seminar on hydrology, National Institute of Hydrology, Roorkee, India. http://​users.​physics.​harvard.​edu/​~wilson/​arsenic/​references/​singh.​pdf. Accessed 25 June 2013, 2004; Ahamed S, Sengupta MK, Mukherjee A, Hossain MA, Das B, Nayak B, Pal A, Mukherjee SC, Pati S, Dutta RN, Chatterjee G, Mukherjee A, Srivastava R, Chakraborty D, Sci Total Environ 370:310–322, 2006; Nickson R, Sengupta C, Mitra P, Dave SN, Banerjee AK, Bhattacharya A, Basu S, Kakoti N, Moorthy NS, Wasuja M, Kumar M, Mishra DS, Ghosh A, Vaish DP, Srivastava AK, Tripathi RM, Singh SN, Prasad R, Bhattacharya R, Deverill P, J Environ Sci Health A 42:1707–1718, 2007). Further, the detection of As in the groundwater of several districts of Manipur, which are part of the Chindwin-Irrawaddy basin (Chakraborti D, Singh EJK, Das B, Shah BA, Hossain MA, Nayak B, Ahamed S, Singh NR, Environ Geol 56:381–390, 2008; Oinam JD, Ramanathan AL, Linda A, Singh G, Environ Earth Sci 62:1183–1195, 2011, Oinam JD, Ramanathan AL, Singh G, J Asian Earth Sci 48:136–149, 2012; Singh EJK, Gupta A, Singh RM, Environ Sci Pollut Res 20(4):2421–2434, 2013), suggests possible As contamination of groundwater in the river valleys of Myanmar as well. Arsenic in the groundwater of this area is derived from the microbial reductive dissolution of iron (Fe) oxyhydroxide and subsequent release of the sorbed As (Nickson RT, McArthur JM, Ravenscroft P, Burgess WG, Ahmed KM, Appl Geochem 15:403–413, 2000; Winkel L, Berg M, Amini M, Hug SJ, Johnson CA, Nat Geosci 1:536–542, 2008). The presence of arsenic in this region is, therefore, a natural phenomenon that warrants realistic assessment of the risks involved followed by proper, often locale-specific management in order to reduce public misery while achieving safe and sustainable utilization of surface- as well as ground-water resources. The problem of arsenic contamination of groundwater in the lower Ganga basin state of West Bengal and in Bangladesh has been amply highlighted (Nickson R, McArthur J, Burgess W, Ahmed KM, Ravenscroft P, Rahmann M, Nature 395:338, 1998, Nickson RT, McArthur JM, Ravenscroft P, Burgess WG, Ahmed KM, Appl Geochem 15:403–413, 2000; Chowdhury UK, Biswas BK, Chowdhury TR, Samanta G, Mandal BK, Basu GC, Chanda CR, Lodh D, Saha KC, Mukherjee SK, Roy S, Kabir S, Quamruzzaman Q, Chakraborti D, Environ Health Perspect 108(5):393–397, 2000; Smith AH, Lingas EO, Rahman M, Bull World Health Organ 78:1093–1103, 2000; Rahman MM, Chowdhury UK, Mukherjee SC, Mondal BK, Paul K, Lodh D, Biswas BK, Chanda CR, Basu GK, Saha KC, Roy S, Das R, Palit SK, Quamruzzaman Q, Chakraborti D, Clin Toxicol 39(7):683–700, 2001; Fazal MA, Kawachi T, Ichion E, Water Int 26(3):370–379, 2001; Chakraborti D, Das B, Rahman MM, Chowdhury UK, Biswas B, Goswami AB, Nayak B, Pal A, Sengupta MK, Ahamed S, Hossain A, Basu G, Roychowdhury T, Das D, Mol Nutr Food Res 53:542–551, 2009) since long, while that in the middle Ganga plain is relatively less widely known, although the situation may be no less alarming in this region as well.