Evaluation of ground water quality and health risk assessment due to nitrate and fluoride in the Middle Indo-Gangetic plains of India

Abstract

Fluoride and nitrate are the most widespread toxic pollutant elements present in groundwaters in large parts of India. The study assessed the groundwater quality and non-carcinogenic health risk due to fluoride and nitrate. Groundwaters were alkaline in reaction with the predominance of sulfate > bicarbonate > chloride > nitrate > fluoride. About 83.8% of the samples were poor in water quality and 77 and 93% of the samples had nitrate and fluoride content above the permissible limit for drinking. Principal component analysis suggested that alkaline pH of groundwater was due to presence of high bicarbonate and low calcium concentration (resulting from precipitation of calcium as calcium carbonate), that also favored release of fluoride. Cluster analysis indicated a common source of anions and cations (Na, Ca and Cl) and the influence of anthropogenic activities in groundwater nitrate contamination; but a geogenic source for fluoride and the influence of alkaline water on weathering of fluoride bearing minerals. The hazard quotient for infant, children and adults due to nitrate was 2.8, 2.19 and 2.0 and due to fluoride was 3.39, 2.64 and 2.42 respectively and 99% of the samples were above the cumulative hazard index implicating that groundwater was unsafe for drinking.

Keywords:

• groundwater
• drinking
• fluoride
• nitrate
• hazard quotient
• hazard index

Acknowledgement

The authors are thankful to the Department of Soil Science and Agricultural Chemistry, Banaras Hindu University, for providing the necessary facilities.

Conflict of interest statement

The authors declare that there is no conflict of interest.

Data availability statement

Data available on request from the authors