Heavy metal characterisation in surface sediments off southeast coast of India: Implication on marine pollution

Abstract

The present study investigated heavy metals (Mn, Cr, Cu, Ni, Pb, and Zn) distribution in the surface sediments off Karaikal – Velankanni offshore along the east coast of Bay of Bengal as an indicator of marine pollution during 2004-2005. The sediments were analyzed for sand, silt, clay ratio, CaCO₃, organic matter, and heavy metal (Mn, Cr, Cu, Ni, Pb, and Zn) contents. The contamination factor (CF) values for the heavy metals are found to be in the order: Mn >Cr >Ni >Zn >Cu >Pb during August 2004; and during January 2005 the CF values were found to be in the order: Zn >Mn >Cu >Ni >Pb >Cr. Zn contamination was found to be low to moderate. 10 samples were found with low and moderate Mn contamination. All the samples displayed moderate contamination with Cu, Ni, and Pb. Among the selected sediments, those which are collected from Karaikal and Velankanni shore were found to be highly contaminated by heavy elements due to the discharge of effluents from petrochemical, oil spills, port activity, and shipping activities. The occurrence of a wide range of elements in coastal sediments is mainly related to the textural variability of sediments during 2004 and 2005.