Pollution index and health risk assessment of arsenic through different groundwater sources and its load on soil-paddy-rice system in a part of Murshidabad district of West Bengal, India

The present study investigates the As-contamination scenario in groundwater and treated drinking water sources from all the 9 gram panchayats under Raninagar-II block, Murshidabad. Approximately 54.6 % of groundwater samples from the domestic and community tube-wells (n = 366) are with As concentration above the permissible limit in drinking water (10 mu g/l); while 37.3 % of groundwater samples from agricultural tube-wells (n = 67) are As-contaminated above its recommended value in irrigational water (100 mu g/l). Malibari-II is the worst affected gram panchayat with mean As concentration of 141 mu g/l (range: <3-995 mu g/l; n = 67) in domestic tube-wells and 294 mu g/l (range: 69.7-990 mu g/l; n = 16) in irrigational water. Arsenic-Iron pollution index assessment and ecological risk analysis state that the groundwater of the study area is sternly polluted. About 12.5 tonnes of As is withdrawn every year through irrigational water in the entire block. Bio-accumulation of As in rice grain (1.78) and paddy whole grain (2.67) shows the potential of hyper-accumulation. The concentrations of two essential micro-nutrients in groundwater (Selenium and Zinc) are low (mean: 0.57 and 84.5 mu g/l, respectively) which encourages the poor health of the local inhabitants. The populations can be expected to suffer from serious cancer and non-cancer risk through contaminated drinking water where the studied adult males face higher risk than the females. The R.O. and Sajaldhara water treatment plants show 77.6 and 74.4 % of As removal efficiency; however, dug wells are the safest drinking water source among all the available sources with a natural Fe/As ratio of 66.1 and account for lowest health risk according to SAMOE.