Physicochemical and heavy metal pollution level in Hindon River ecosystem: An implication to public health risk assessment

The study was conducted to determine heavy metal contamination and physicochemical parameters in Hindon River's water. The parameters evaluated included cadmium (Cd), copper (Cu), chromium (Cr), iron (Fe), manganese (Mn), zinc (Zn), and lead (Pb), as well as pH, electrical conductivity (EC), turbidity (TUR), total dissolved solids (TDS), total hardness (TH), total alkalinity (TA), dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), chloride (Cl⁻), calcium (Ca), sulfate (${\text{SO}}_{4^{2-}}$) and nitrate (${\text{NO}}_{3^{-}}$). The findings showed the distribution of metals in river water. Some of the values of Cd, Cu, Cr, Fe, Mn, Zn, and Pb in surface water were above the standards set by the Bureau of Indian Standards (BIS). The mean concentrations of physicochemical parameters in surface water sometimes exceeded the BIS standards due to untreated effluent discharge. All the Water Quality Index (WQI) values were above 100; therefore, the water was unsuitable for human consumption. The heavy metal pollution index (HPI) showed that Station 1 (S1) is the most polluted, followed by the S3 and S5. Multivariate statistical analysis showed that most heavy metals (HMs) in river water originated from artificial or anthropogenic sources, that is, human sources. The calculated hazard quotient (HQ) and hazard index (HI) showed that the oral ingestion route could be dangerous to humans (both adults and children) since the HQ and HI values were higher than the acceptable limits (HQ > 1). Dermal exposure assessment showed that the S1 was more dangerous to children's and adults' health than the S3 and S5. This trend showed that the Hindon River was polluted due to many untreated industrial effluents being discharged. The research highlights the pollution level in the Hindon River, and there is a need for proper monitoring and control to maintain the sustainability of the river ecosystem.