Ecological risk assessment and seasonal variation of heavy metals in water and sediment collected from industrially polluted Cuddalore coast, Southeastern India

Abstract

Concentrations and ecological risk assessments for four heavy metals (Cu, Cd, Pb, and Zn) were analysed. The seasonal variations of metals in water and sediments from sites with different anthropogenic activities were assessed. Outcomes revealed higher concentration of metals in sediments compared to water. Order of metals in water is Zn>Pb>Cu>Cd, and in sediment is Zn>Cu>Pb>Cd. Seasonal distribution of metals in the water was premonsoon>postmonsoon>monsoon>summer, and in the sediment was summer>postmonsoon>monsoon>premonsoon. Monsoon season loaded the estuarian ecosystem with heavy metals from the Cuddalore industries. Later, during summer months, the metals accumulated in the sediments and deposited in the mouths of Uppanar and Gadilam rivers. Environmental pollution indices, such as geo-accumulation index, contamination factor, and ecological risk index, pointed that Cd posed a greater risk to the ecosystem compared to other metals. Through multivariate statistical analyses, metal sources were linked to industrial wastes, chemical fertilizers, shipping activities, and fishing and boat activities which pollute the Cuddalore coast. Continuous monitoring for heavy metals and their ecological impacts in the Cuddalore coast is essential to remediate the metal pollution effectively.