Risk Assessment of Groundwater Contamination by Heavy Metals: A Multivariate Statistics and Index-Based study

Abstract

Heavy metal pollution in water is a pressing global concern, posing significant health risks to humans through multiple exposure pathways. Groundwater in the districts of Prayagraj, Lakhimpur, and Ballia in Uttar Pradesh, India, is affected by heavy metal contamination, largely due to the region’s geological soil profile. This study aimed to assess the potential health risks posed by heavy metals (As, Cd, Cr, Pb, Cu, Fe, Mn, Ni, Se, Co, Mo and Zn) in groundwater from the Gangetic Plain. The dataset was normalized using the Shapiro-Wilk method and analyzed using Principal Component Analysis (PCA) in OriginLab (v10.15) to identify key factors influencing heavy metal distribution. The Heavy Metal Pollution Index (HPI) and Health Risk Assessment were applied to evaluate the extent of contamination. Results showed that concentrations of Fe, As, Mn, and Pb exceeded the permissible limits set by the Bureau of Indian Standards (BIS). HPI analysis indicated that 70% of groundwater samples from the Ballia region exhibited very high pollution levels. Correlation analyses suggested that industrial and agricultural activities are the primary sources of heavy metal contamination, rather than natural geogenic processes. Based on Hazard Quotient values, Pb and As were identified as the major contributors to the elevated Hazard Index (HI). These findings underscore the urgent need for mitigation strategies, consistent monitoring, and effective treatment measures to ensure access to safe drinking water.