Assessment of Integrated Health and Ecological Risks linked with Heavy Metal Pollutants in the Agro-industrial basin of Kali River, India

Persistent elevated levels of heavy metals in river water used for irrigation can accumulate in aquatic and terrestrial organisms, disrupting the food chain, altering species compositions, and leading to ecosystem instability. An integrated risk assessment is thus essential to comprehend the cumulative effects of ongoing contamination, offering insights into the severity of hazards associated with heavy metal containing river water. The present research aims to analyze the spatial and temporal variations in the hazard index (HI) and ecological risk index (ERI) based on surface water samples collected along the Kali River. Further, this study pinpoints major heavy metals posing heightened risks, aiming to identify hotspot zones within the river basin. Seasonal water quality monitoring revealed elevated concentrations of Cr, Mn, and Ni during the pre-monsoon. Conversely, in the post-monsoon period, Cr, Fe, Mn, Zn, Cd, and Pb exceeded the drinking water standards established by BIS 2012 across the entire stretch of the Kali River. The ERI findings indicated that during the post-monsoon season, none of the water samples fell into the low ecological risk, whereas about 80% of samples were classed as low ecological risk during the pre-monsoon season. The observed seasonal shift in the computed ecological risk is likely attributed to the wash-off effect and the discharge of agro-industrial waste during the post-monsoon period. Moreover, the values of the ecological risk are higher at the upstream water sampling locations compared to downstream, indicating the effect of the dilution caused by domestic sewage originating from economically developed districts in western Uttar Pradesh state. Similarly, the findings from HI associated with human health indicate that both adults and children face potential carcinogenic and non-carcinogenic risks at all water sampling locations during post-monsoon season. However, in pre-monsoon season, only 34% of water sampling sites reported non-carcinogenic risk. Finally, a correlation was established between predicted risk indices and the observed data encompassing human health, community feedback, and ecological survey results. The findings indicate a robust correlation of 76% among sampling locations along the Kali River, indicating elevated environmental vulnerability in the basin. This study highlights the degraded condition of the Kali River ecosystem, posing threats to both humans and ecology. This necessitates immediate action for effective mitigation strategies to safeguard public health, preserve ecosystems, ensure the safety of agricultural and aquatic resources, and adhere to regulations for sustainable water management in the basin.