Assessment of Heavy Metal Contamination and Associated Health Risks in Gomati River water in Lucknow

Heavy metal contamination in urban rivers poses significant ecological and public health challenges, particularly in rapidly urbanizing regions. This study evaluated the spatial distribution of heavy metal contamination along a 61 km stretch of the River Gomti in Lucknow, India, using the Heavy Metal Pollution Index (HPI), human health risk assessment, and multivariate statistical analyses. The HPI results revealed severe water quality deterioration, with 30% of the sampling sites categorized as highly polluted (HPI > 30) and 60% as critically polluted (HPI > 100). The mean HPI value of 354.01 substantially exceeded the critical threshold, indicating widespread heavy metal contamination throughout the study reach. Human health risks associated with exposure to contaminated river water were assessed using Chronic Daily Intake (CDI), Hazard Quotient (HQ), Hazard Index (HI), and Cancer Risk (CR). Several metals exhibited HQ values greater than 1, indicating potential non-carcinogenic health effects, while HI values exceeded the acceptable safety limit at most sampling locations, reaching a maximum of 4.58. Carcinogenic risk assessment for chromium (Cr), arsenic (As), cadmium (Cd), and lead (Pb) demonstrated Total Cancer Risk (TCR) values above the acceptable limit (1 × 10⁻⁴), with As and Pb identified as the primary contributors to cancer risk. Pearson correlation analysis, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA) revealed strong associations among Pb-Cd and Cu-Zn, suggesting common pollution sources, whereas significant correlations (r = 0.51–0.89) among As, Pb, and Mn indicated predominantly anthropogenic inputs from industrial discharges, untreated sewage, and agricultural runoff. The findings highlight the critical pollution status of the River Gomti and emphasize the urgent need for effective wastewater treatment, stricter pollution control strategies, and long-term water quality monitoring to safeguard aquatic ecosystems and protect public health.