Insights into Water Quality of River Yamuna, India: A Comprehensive Spatial-Temporal Analysis Using Advanced Indices and Multivariate Statistical Techniques

The escalating issue of heavy metal pollution is a global concern, primarily due to its toxic and persistent nature, further exacerbated by its rising concentrations in water bodies. This study examines spatial-temporal dynamics of water quality along the Yamuna River through physicochemical parameters, heavy metal analysis, advanced approaches such as Heavy Metal Pollution Index (HPI), Ecological Risk Index (ERI), Human health risk assessment and multivariate statistical techniques (Principal Component Analysis). It was identified that Wazirabad after drain (WBAD) region exhibits poor water quality, with levels of Dissolved Oxygen (DO), Ammonia, and five heavy metals (Fe, Mn, Pb, Cr, and Ni) exceeding Bureau of Indian Standards (BIS) permissible limits. During the pre-monsoon season, HPI values surpassed the critical threshold (100) in Wazirabad before drain (WBBD) (146.69), WBAD (267.13), and Prayagraj (PJ) (204.80), while in the post-monsoon season, only PJ (115) exhibited elevated HPI values. Ecological risk assessment highlighted Cd, Pb, and Ni as major risk elements, posing significant environmental threats. Health risk assessment demonstrated that WBBD, WBAD, and PJ continue to pose significant non-carcinogenic and carcinogenic risks to both children and adults. Pearson Correlation analysis and PCA identified two distinct groups of heavy metals, suggesting distinct contamination sources for Co, Cd, and Cu compared to the Fe–Cr–Pb–Mn–Zn–Ni group. This thorough study not only emphasizes the critical condition of water quality in the Delhi region but also provides valuable insights into the sources and distribution of heavy metals, offering a valuable foundation for targeted intervention and mitigation strategies to address the pressing issue of heavy metal pollution.