摘要
Contamination of groundwater is posing serious threat to the household and drinking water supply schemes all over the world. Increase in concentration of Fluoride (F−) and Nitrate (NO3−) in the groundwater is frequently reported from Indian subcontinent. In this paper, we have studied the F− and NO3− concentration in the Lower Bhavani Basin located in Tamil Nadu state in south India. This is a hard rock dominated semi-arid climatic region, where groundwater is the potential source of drinking and agricultural purposes. Among the total 36 groundwater samples, 22% showed a higher concentration than the permissible of Indian Standard 1.2 mg/L for fluoride. The influence of geochemical factors such as pH, conductivity and Na/Ca ratios were identified. On the other hand, 16% of the samples exceeded the permissible limit of nitrate (45 mg/L). The source of nitrate is identified preliminarily as fertilizer usage in the agricultural fields and secondarily from the sewages. Kriging based Geostatistical model were used the spatial variation mapping of these ions. For fluoride, spatial variation maps showed definite correlation with the Geological formations, i.e., the high fluoride samples were observed in the NE regions of the basin. In case of Nitrate, higher concentration was observed in the Southern part of the basin. Mapping of water quality parameters spatially is proved to be an effective tool for better visualization and management of the groundwater resources in the study area.