Fluoride and Nitrate Geochemistry of Groundwater from Kadiri, Mudigubba and Nallamada Mandals of Anantapur District, Andhra Pradesh, India

B.Muralidhara Reddy; V. Sunitha; M.Ramakrishna Reddy
Groundwater forms the major source of drinking water in the rural areas of most of the developing nations in the world. Presence of high concentration of fluoride and nitrate in groundwater is a major problem in many countries as it causes health related problems. The present study was carried out with the objective of determining the causes for higher fluoride and nitrate concentration in groundwater in parts of Anantapur District, Andhra Pradesh, India. Fluoride and nitrate concentration in groundwater of this area was analysed by collecting groundwater samples from forty-four representative dug wells. Samples were collected during March 2009-January 2010. The concentration of fluoride in the water samples ranged between 0.1 mg/l and 7.0 mg/l 76% of the water samples contain fluoride above the maximum permissible limit. Possible sources of fluoride in groundwater are weathering and leaching of fluoride bearing minerals from the basement granitic rocks of this region under alkaline environment. By nature, the granitic rocks of this area possess fluoride values greater than the world average content in granitic rocks. The highest concentration of nitrate recorded during the sampling period was 110 mg/l and the lowest concentration was below detection limit. Taking into consideration 45mg/l of nitrate as the maximum permissible limit for drinking water set by BIS, it was found that 12% of the groundwater samples collected from this study area possessed nitrate concentration beyond the limit. Overall, dug wells present in agricultural fields had nitrate levels within permissible limits when compared to those groundwater samples from dug wells present in settlements which were used for domestic purpose. This indicates that the high nitrate concentration in groundwater of this area is due to leaching from indiscriminate dumping of animal waste. Anthropogenic activities like application of fertilizers for agriculture contribute only little to the groundwater dug well as fluoride. The major contribution of the paper is that the dug wells in the Kadiri, Mudigubba and Nallamada Mandals of Anantapur District, Andhra Pradesh have been demarcated into safe and unsafe dug wells for consumption of water with respect to fluoride.
Groundwater; Fluoride; Nitrate; Anthropogenic; Anantapur District; India
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