The present research reports the level of nitrate (NO3-), associated health risks and possible sources of contamination in groundwater from south India. Many samples (32%) are above or approaching the recommended level of NO3- for safe drinking water. The correlation analysis indicates different sources of NO3- contamination in different regions rather than a common origin. The isotopic measurements provide information about potential nitrogen sources contributing NO3- to the groundwater. Based on isotope analysis, the sources of NO3- in the groundwater of this region are likely to be from (a) septic sewage (b) organic nitrogen (animal and livestock excreta) (c) sewage (domestic & chemical fertilizers). Among the sample analyzed sewage, manure and septic sewage contribute 46%, 23% and 31% NO3- to groundwater. The HQ > 1 indicates non-carcinogenic health risk due to consumption of high NO3- in drinking water. Among the studied age groups, infants are exposed to higher risk than children and adults. Results indicate that groundwater of this region is polluted with NO3- due to anthropogenic activities. Continuous consumption of such water may pose serious health risk to the residents.
Keywords: Correlation; Groundwater; Health risk; N-isotopes; Nitrate.
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