Geochemistry of Core Sediments from Tropical Mangrove Region of Tamil Nadu: Implications on Trace Metals

Abstract

The present study aims to determine the concentrations of certain trace metals (Fe, Mn, Cr, Cu, Pb, Zn, Co, Ni, Ba, Sr, V and Rb) and to identify the possible sources of the trace metals with multivariate analyses and assess the metal contamination using the enrichment factor (EF) and geo-accumulation index (Igeo) from the two core samples taken from Pichavaram lagoon. Pichavaram mangrove is a dynamic intertidal environment lying in between Vellar and Coleroon estuaries in Cauvery delta along the east coast of India. High OM in the present study is noted in both core samples which are mainly controlled by productivity and sediment texture. The increase of trace metals concentrations was observed at lower intersects which indicates that the trace metals were reprecipitated around the redox boundaries. Further it signifies that the enrichment of metals in C1 core sample is closely related to the diagenetic. Factor 1 with significant positive loadings on Mud and good loadings on Fe and Mn suggests the associations of these metals with finer sediment fractions and aluminosilicates. These elements to be enriched in the clay fraction in both core samples. They are mainly related to anthropogenic inputs and reflect the complexing nature of the organic matter. Igeo studies confirm the contamination of the study area. Overall the study highlights significant anthropogenic contributions in terms of heavy metal pollution. Comparative data for normalized enrichment factors and the modified degree of contamination show that Pichavaram sediments have suffered significant systematic heavy metal contamination following catchment urbanization.