Groundwater Contamination with Nitrate and Human Health Risk Assessment of North East Alluvial Plains of Bihar, India

Groundwater is natural resources which supplies almost half of all drinking water in the world and plays a key role in food production. Consuming water containing high nitrate concentration have immediate effect on infant and could cause the risk of diseases Methemoglobinemia in which blood lacks the ability to carry sufficient oxygen to the individual body cells. As difference in nitrate concentration in water, made it important to study the undesirable effect of it. In rural areas, groundwater contamination is a problem related to the excessive use of chemical fertilizers by local farmers. Shallow groundwater plays a vital role in water use and the yield of Maize. Nitrogen application significantly affects crop uptake and utilization of water from irrigation, but little is known about groundwater use. Farmers are applying nitrogen on an average 278 kg/ha in Kharif maize, which is about 131.72% more than the RDN of Kharif maize i.e. 120 KgN/ha. The mean value of N application by farmers ranges from 251-323 kg/ha. The Maximum rate of N application was observed in Khagaria (323 kg N/ha) followed by Madhepura (275.08 kg N/ha) and minimum in case of Saharsa district (251.16 kg N/ha). The application rate of nitrogenous fertilizer, varying from 109.25% to 169.16% over the RDN, resulting in NO3- leaching. The groundwater and surfacewater from 12 villages was collected and various quality parameters were analysed. The nitrate in ground water varied (1.87- 6.19 mg/L) and surface water (1.87 – 3.84 mg/L) being maximum concentration of nitrate in Madhepura district. The present study on nitrate leaching in soil, its level of contamination in ground water and human health risk assessment by chronic daily intake of nitrate and Hazard Quotient (H.Q) values in the study area of Khagaria, Saharsa, Madhepura and Supaul has been carried out in the eastern alluvial region of Bihar.