An overview of heavy metal contamination in coastal sediments of Sri Lanka

Abstract

Coastal sediments are often subjected to heavy metal contamination as they reside at the marginal environments of anthropological water releases. These sediments provide the habitat for marine aquatic life of seafood. Therefore, heavy metal contamination in coastal sediments is one of the major environmental concerns. The coastal belt of Sri Lanka is highly urbanized with high population (59% of Sri Lankan population) and is mostly depend on the sea. Therefore, anthropogenic inputs of pollutants in to the marine environments have been increased during last decades. Heavy metal contamination of the coastal sediments of Sri Lanka has been discussed by several studies, focusing on selected coastal regions. In this article, previous studies have been reviewed in order to understand the contamination status and ecological risks due to heavy metal accumulations. Despite the sampling location, the elemental distribution of coastal lagoonal sediments shows similar trend indicating the dominance of natural elemental sources rather the anthropogenic influences. The concentrations of As and Cr in sediments are high compared to the upper continental crust values which is a characteristic feature in possible source rocks, soils and sediments of Sri Lanka. The results of the previous studies indicate that coastal sediments are low to moderately contaminated but not at ecological risk. However, anthropogenic activities are highly variable across the coastal regions. Since limited results of the previous studies is not enough to get an overview of the heavy metal concentrations around the island, urgent need for a spatial and temporal geochemical database for coastal sediments of Sri Lanka is emphasized.