Carriers of contamination: heavy metals in Ganga River suspended particles
Mohit Aggarwal, Pradyut Anand, Deepika Varshney, Bayram Ateş
Abstract
Abstract The Ganga, a critical lifeline for nearly 400 million people, is increasingly threatened by heavy metal contamination from industrial effluents, agricultural runoff, and urban discharge. This study quantified eight heavy metals—iron (Fe), manganese (Mn), zinc (Zn), chromium (Cr), lead (Pb), nickel (Ni), copper (Cu), and cadmium (Cd)—in suspended solid particles collected from ten sites along a 210-kilometer stretch between Kanpur and Prayagraj, Uttar Pradesh, in July 2024. Suspended particulates were isolated by membrane filtration and analyzed using Atomic Absorption Spectrophotometry (AAS). Median concentrations (μg/g) were Fe (47,246), Mn (940), Zn (206), Cr (122), Pb (65.5), Ni (64.8), Cu (61.3), and Cd (1.61), with the highest values for Fe, Mn, Zn, Pb, and Cu observed at Nawabganj and Manikpur. Enrichment Factor (EF) analysis, using Fe as the reference element, indicated minor anthropogenic enrichment for Pb (1.32), Cd (1.27), Zn (1.20), Cr (1.13), and Ni (1.07), particularly at Dalmau Bridge, Unchahar, Nawabganj, and Manikpur. Mn and Cu showed EF values below 1, suggesting predominantly natural origins, although strong inter-metal correlations point to potential industrial sources for Cu. Multivariate statistical tools (PCA, clustering) revealed spatial contamination patterns and identified Nawabganj and Manikpur as consistent pollution hotspots. Compared to global rivers, the Ganga exhibited significantly higher suspended solid heavy metal loads (e.g., Pb: 65.5 μg g −1 versus Yangtze: 43 μg g −1 ). These findings underscore the urgent need for site-specific pollution control, stricter discharge regulations, and long-term ecological monitoring. This study provides a replicable framework for riverine metal pollution assessment and supports sustainable management initiatives like the Namami Gange program.