NITRATE CONTAMINATION IN GROUNDWATER IN SOME RURAL AREAS OF ANANTAPUR DISTRICT, A.P SOUTH INDIA

Nitrogen, especially in the form of nitrate, is one of the most widely recognized contaminants in aquifer systems and represents a genuine human health threat. High nitrate levels found in drinking water have been proven to be the cause for numerous health conditions. Protecting groundwater from nitrogen contamination is an important public-health concern and a noteworthy national environmental issue in India. Agricultural activities in India account for more than 80% of the total N₂O emissions, including 60 % from the use of nitrogen based fertilizers and 12% from burning of agricultural residues. In spite of groundwater being the major drinking water source, degradation is going unchecked. In agro-economy based rural areas, nitrate contamination is rampant and much attention has not been drawn towards this anthropogenic pollution.Here the results of investigations on groundwater nitrate contamination in the parts of Anantapur district of Andhra Pradesh in south India are discussed.Groundwater samples were collected from 50 selected locations during the pre-monsoon season in May 2015 and post monsoon season in September 2015 and analysed for nitrate and other water quality parameters such as EC, TDS, TH, Ca, Mg, Na, K, CO₃^2-, HCO₃^-, Cl^-, SO₄^2-, NO₃^- and F^-. It is found that the majority of samples possess high nitrate concentration; 60% of samples exceeded the permissible limit of Indian (45 mg/L) and WHO (50 mg/L) drinking water standards. It was observed that the groundwater nitrate concentration in pre monsoon season is higher than the post monsoon. A spatial distribution map of NO₃ showed that the north and NW parts were heavily polluted with nitrate. A positive correlation of NO₃ with EC, Cl^-, SO₄^2- and K suggests that there is an influence of nonpoint pollution. The major sources of nitrate contamination are noted as areas of high fertilizer application, sewage and animal waste dumping yards. The continuous consumption of such water may pose serious health hazardous in local residents. Regulation of these pollutant sources with appropriate and cost-effective denitrification process can restore the water quality in this area.