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- Title
Spatial distribution of nitrate and fluoride pollution and risk assessment in drinking water resources of Chennai, Kancheepuram, and Tiruvallur districts of Tamil Nadu, India.
- Authors
Muththamizh, Bernardshaw; Sowmya, Appunni; Prabhakar, Sivaraman; Muthamilselvi, Ponnuchamy; Kapoor, Ashish; Rajesh, Mathur
- Abstract
Nitrate and fluoride are among the key chemicals that cause large scale health effects through drinking water exposure. In this study, the nitrate and fluoride content from drinking water sources of the Chennai River basin districts of Chennai, Kancheepuram and Tiruvallur in Tamil Nadu, India were analyzed to map their spatial distribution. Out of the 103 groundwater samples analyzed, 84 (81.6%) and 79 (76.7%) samples were found to possess below permissible limits of nitrate (45.0 mg/L) and fluoride (1.0 mg/L), respectively. Chennai city, with high population density was not found to be a nitrate and fluoride endemic region. The maximum nitrate concentrations of 143.9 and 132.0 mg/L were found to occur in water sourced from two relatively isolated hotspots, a borewell in Sottupakkam and an openwell in Sirunallur, respectively of Kancheepuram district. Tiruvallur (maximum 2.7 mg/L at Tiruvallur town) and Kancheepuram (maximum 2.6 mg/L at Chengalpattu town) districts had more than 10 fluoride hotspots each with content higher than the permissible limit, which is most probably due to fluoride leaching from mineral-rich rocks in these regions. The fluoride concentration levels appeared to correlate better against water quality parameters (total dissolved solids, electrical conductivity, alkalinity, total hardness, chloride and sulphate) studied when compared with the nitrate concentration levels. The fluoride concentrations also appeared to have a relatively higher correlation with alkalinity and hardness which can be attributed to concomitant release of bicarbonate, calcium and magnesium ions during the fluoride leaching process from mineral-rich rocks in these regions. Furthermore, the non-carcinogenic health risk associated with nitrate and fluoride in water ingestion in infants, children and adults was evaluated with the United States Environmental Protection Agency (U.S. EPA) method. The percentage exceedance of total hazard index limit for infants, children and adults in Chennai district was 95.8%, 58.3% and 8.3%, respectively, while it was 100.0%, 100.0% and 61.0%, respectively in Kancheepuram district and 97.4%, 97.4% and 57.9%, respectively in Tiruvallur district. These results predict that infants and children from these three districts appear to be highly susceptible to non-carcinogenic nitrate and fluoride induced health hazards, while adults are predicted to be more or less immune to the associated health risks.
- Subjects
CHENNAI (India); POLLUTION risk assessment; DRINKING water; WATER supply; WATER consumption; FLUORIDES; NITRATES; MAGNESIUM ions
- Publication
Desalination & Water Treatment, 2023, Vol 316, p1
- ISSN
1944-3994
- Publication type
Article
- DOI
10.5004/dwt.2023.30096