Distribution and Ecological Risk Assessment of Heavy Metals in the Sediments along the Indian Coast

Metal contamination in sediments remains a significant environmental challenge, highlighting the need for comprehensive assessments to evaluate pollution levels and develop effective remediation strategies. Therefore, sediment quality and ecological risk indices were derived from the metal concentrations in the coastal sediments of India. Overall, mean values indicate metal concentrations are higher in the sampling sites on the west coast than on the east coastal sites. Similarly, the organic and inorganic carbon levels are higher on the west coast than on the east coast. Metal concentrations are higher in Goa, Maharashtra, and Kerala compared to, Odisha, and West Bengal. Statistical analyses including correlation, DFA, RDA, and PCA reveal strong associations between sediment metals and carbon, indicating co-deposition mechanisms influenced by organic matter and fine-grained particles. Geographic variation accounts for over 70% of the total multivariate variance, with Cadmium, Lead, and Zinc posing ecological risk, while Copper and Chromium reflect anthropogenic influence. Overall PLI results suggest that most coastal sediments remain unpolluted. Mostly the levels of Manganese, Zinc, and Cobalt found within sediment quality thresholds, although Copper and Chromium observed with elevated levels at few sites. In contrast, toxic metals such as Cadmium and Arsenic reaching concentrations indicative of significant ecological concern exhibiting more frequent and substantial enrichments along with Lead, and Nickel. These patterns demonstrate that certain toxic metals can persist and accumulate in coastal sediments despite natural dispersion. Overall, the findings emphasize the need for coordinated, large-scale monitoring to identify contamination hotspots and support targeted pollution-mitigation strategies.