Anthropogenic effects on sediment quality of Muthupet mangroves: assessing the sediment core geochemical record.

Abstract

Four cores were collected from Muthupet mangroves, southeast coast of India to evaluate the heavy metal contamination (Ni, Pb, Mn, Zn, V, Sr and Sc) and the associated geochemical parameters viz., texture, CaCO₃ and organic carbon. Textural analysis reveals a predominance of mud. A distinct event is identified at 57.5-60 cm suggesting a change in deposition trend due to the tsunami on 26^th June 1941. The higher values in the lower portion in all the core samples indicate that metals are reprecipitated at deeper levels. According to Geoaccumalation index Muthupet mangroves can be considered to be uncontaminated to moderately contaminated with respect to trace metals. Sediment Enrichment Factor computation indicate that all metals except Ni and Mn in C4 (crustal origin) are of anthropogenic origin. From estimation of toxic unit, it is evident that the sequence for toxicity is C3 > C4 > C2 > C1.