Pollution complexity quantification using NPI and HPI of River Ganga system in Himalayan Region

Abstract

The Ganga river system is a life-sustaining system that offers freshwater to millions in India.This research demonstrated the Ganga River's water quality based on data collected from 20 locations from Upper, middle and foot hills of Garhwal Himalayas. The present study combines the Single-factor Pollution Index (Pi), Nemerow Pollution Index (NPI),Heavy Metal Pollution Index (HPI), and chemo-metric models (Principal Component Analysis: PCA and Cluster Analysis: CA) to establish a cause-effect relationship between any change in water quality and their sources.The water samples were analyzed to measure the concentrations of 10 potentially toxic elements (PTEs) such as Zn, Pb, Mn, Fe, Cu, Al, Ni, Cd, Mg, and Co. Results revealed that river water is highly contaminated (HPI > 30) at downstream sitescompared to upstream sites,resulting froma rapid increase in agricultural, industrial, and domestic activities. Regular monitoring and prevention of pollution techniques are required to protect river water from heavy metal toxicity. Some of the heavy metals tested were beyond industry guidelines, necessitating a health risk assessment. The health risk evaluation for all sites revealed that no single heavy metal is particularly hazardous, but the cumulative impact, as indicated by the hazard index, is (HI). For all seasons, HI far surpassed the threshold value (1). This is a reason for concern for both adults and children who have ingested the water. Heavy metal pollution was geogenic, with anthropogenic activities exacerbating it.