Characteristics, water quality index and human health risk from nitrate and fluoride in Kakhk city and its rural areas, Iran

Abstract

Groundwater is an important source for drinking water supply in the arid and semi-arid regions around the world. Eighty four groundwater samples collected from Kakhk and its all rural areas were evaluated for drinking quality using the water quality index (WQI). Additionally, the human health risks associated with nitrate and fluoride concentrations in drinking water were estimated for children and adults using the United States Environmental Protection Agency (USEPA) method in the investigated areas. Parameters including potassium, carbonate, bicarbonate, chloride, sulfate, nitrate, fluoride, calcium, magnesium, sodium, pH, total hardness and electrical conductivity were analyzed. Among these, levels of potassium, carbonate, nitrate and fluoride in all areas were within the permissible limits of World Health Organization (WHO) for drinking water. The mean concentrations of nitrate and fluoride in the study areas were 20.00 ± 14.81 mg/L and 0.32 ± 0.17 mg/L, respectively. The WQI classification showed that 16.6 %, 38 % and 45.2 % of water resources had excellent, good and poor water quality, respectively. 40.4 % of the areas had Hazard Quotient (HQ) values more than one (HQ ≥ 1), indicating the possibility of being non-carcinogenic risk of nitrate through water consumption for children. But values of HQadults (for nitrate), HQchildren (for fluoride) and HQadults (for fluoride) all were less than 1 (HQ < 1), showing little or no risk from water consumption containing these elements in the areas. Regarding all of the measured parameters, higher CDI and HQ values were seen for children compared to adults. This study is useful, as it is the most comprehensive water quality assessment research conducted so far in Kakhk and its rural areas and will be a reference to future studies.