Spatial distribution of selected heavy metals and their probable ecological risk in coastal sediments of Tuticorin, southeast coast of India

Asha, P S and Lavanya, R and Usharani, A and Muniswaran, Bose Ramar and Jayasankar, Reeta (2026) Spatial distribution of selected heavy metals and their probable ecological risk in coastal sediments of Tuticorin, southeast coast of India. Journal of the Marine Biological Association of India, 68 (1). pp. 24-31. ISSN 2321-7898

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Abstract

The rise in industrial and urban activities has exacerbated soil contamination with metals, making it a pressing global issue. In this study, eight stations (St.1 to 8) were identified to assess the concentrations of heavy metals such as lead (Pb), cadmium (Cd), nickel (Ni), and mercury (Hg) in the sediments of the Tuticorin coast across four seasons: Monsoon, Post-monsoon, Summer, and Pre- monsoon. The dried, finely ground sediment samples were digested and analysed for heavy metals using standard procedures. Elevated mean concentrations of Cd (4.95±0.28 μg g-1) and Hg (0.26±0.06 μg g-1) were recorded at St.1. At the same time, Ni (35.59±4.16 μg g-1) and Pb (26.42±10.1 μg g-1) showed maximum levels at the St.2. According to the various Sediment Quality Guidelines (SQGs), the study indicated a low probability of adverse effects from Hg, Ni, and Pb along the Tuticorin coast. However, Cd concentrations pose a probable ecological risk with values exceeding the Probable Effect Level (PEL) to Severe Effect Level (SEL) in most stations, indicating potential impact on the benthic ecosystem. A moderate pollution level of Cd (<6) was observed at all stations as per the Environmental Protection Agency (EPA) guidelines. Except for Cd, concentrations of all other metals remained within the PEL thresholds prescribed by the Canadian Environmental Quality guidelines for the protection of aquatic life. The highest pollution index level was noticed at St. 2 and St.1, which reflects the possible anthropogenic impacts. The results of the study emphasise the urgent need for targeted mitigation measures to reduce metal contamination, especially that of Cd, along the Tuticorin coastal belt.

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