Assessment of trace metal contamination and associated health risks in the Chaliyar river basin, Kerala

Water sustains life but water resources are degraded by industrial discharges and agricultural runoff in which heavy metals are concerning pollutants. This study focuses on an integrated approach for riverbank soil assessments in the Chaliyar river of Kerala, India using a comprehensive multifactor risk assessment. Thirteen surface water samples and riverbank soils were analysed for heavy metal concentrations (As, Cd, Cr, Cu, Ni, Pb and Zn). Elevated concentrations of Cd (0.05-0.1 mg/L) and Pb (1.75–1.93 mg/L) were detected in the surface water samples when compared to the drinking water permissible limits (Cd-0.003 mg/L and Pb-0.01 mg/L). The comparison with irrigational water standards revealed that only Pb values are optimal for irrigation throughout the sampling sites with a baseline value of 5 mg/L. The riverbank soils also exhibited elevated Cd concentrations (Mean = 0.654 mg/kg) which places Cd in the moderately polluted category along with a Geoaccumulation index ranging from 0.152 to 1.152. The Ecological risk indices in the riverbank soil (60.17–124.47) were categorized under the mild risk status in all locations. For the biological risk index, the sampling locations ranged from non-toxic to slightly toxic. Carcinogenic exposure assessment revealed greater ingestion risk as compared to the dermal risk. These findings suggest that assessment of site-specific metal toxicity is essential for implementing effective remedial strategies to combat riverbank soil and surface water contamination.