Nitrate pollution in groundwater: its causes and effects in central part of Suvarnamukhi River Basin, Karnataka Radhika K.N.1,*, Rao K.L. Narahari1, Krishnamurthy J.2, Neelakantarama J.M.3 1Department of Geology, Bangalore University, Bangalore 2ISRO Headquarters, Antariksh Bhavan, Bangalore 3Geological Survey of India, Mangalore *knradhika and drkln21@rediffmail.com
Online published on 3 December, 2011. Abstract Groundwater is the major source of drinking water in the sub-basins of the central part of Suvarnamukhi River Basin. Chemical analysis is carried out for 55 groundwater samples collected during pre-monsoon and post-monsoon seasons from five sub-basins. The average nitrate concentration is 65.96 and 97.17 ppm in pre-monsoon and post-monsoon seasons respectively. According to Bureau of Indian Standards (BIS), the maximum desirable and permissible limit of nitrate is 45ppm. In the study area, 25 samples (45%) and 32 samples (58%) in pre-monsoon and post-monsoon seasons are not suitable for drinking purpose with a seasonal variation of 43%. Seven samples of post monsoon have increased NO3− concentration compared to pre-monsoon season. The interrelationship of nitrate with other cations and anions suggest the most possible sources of nitrate as non-point sources (leaching mechanism of nitrate due to extensive use of fertilizers) and to some extent point sources (cattle sheds and poultry farms, leakages from septic tanks, sewerage effluents). The nitrate distribution map shows anomalous zones in the central and south eastern part of the study area in both pre and post-monsoon seasons suggesting that groundwater here is completely polluted and is unfit for drinking. The north western portion of the study area has high NO3− concentration during post monsoon season suggesting that the water is polluted due to application of nitrate rich fertilizers. Top Keywords Nitrate concentration, Point sources and non point sources, Anomalous zones, Groundwater, Fertilizers, Suvarnamukhi. Top |