A baseline study on trace metals concentration and its ecological risk assessment from the coast of South Andaman Island, India

Abstract

The rapid urbanization processes in island coastal areas has led to serious pollution in the marine environment. Less is known about the trace metal speciation and ecological risk (ER) in the coastal sediments of island areas under various human activities pressures, which is essential to address the connection between metal pollution and anthropogenic impacts. We report here the trace metals concentration and its ecological risk on the coast of South Andaman Island (SAI). A total of 23 study locations were selected (March 2013) and the surface sediments were studied for trace metal concentrations such as Iron (Fe), Manganese (Mn), Chromium (Cr), Cobalt (Co), Copper (Cu), Nickel (Ni), Arsenic (As), Zinc (Zn), and Lead (Pb). Moreover, the marine pollution indices such as Enrichment Factors (EFs), Geo-accumulation Index (Igeo), Contamination Factor (CF), Pollution Load Index (PLI), and Sediment Pollution Index (SPI) were also studied to consider the spatial distribution of trace metals. The concentration values of trace elements are found in the order of Fe > Mn > Cr > Ni > Zn > Cu > Co > Pb > As. The CF analysis suggested that the South Andaman coastal sediments are a relatively significant level of elements contamination. Besides the EF and Igeo values also showed significant enrichment in the nearby settlement area and indicated that the study locations are coming under unpolluted and moderately polluted categories. The PLI and SPI analyses showed that the inner Bay region (stations 1, 2, 3, and 20) of Port Blair Bay is a highly polluted area and its ER values suggest that the sediments fall under the moderate risk (69.56%) and considerable risk (30.43%) categories. The statistical analysis clearly indicated that the accumulations of trace elements in the study locations are due to anthropogenic inputs from the adjacent land-based sources. Spatial data on the heavy metal concentration of the studied site would help the policymaker/environmental managers to identify the vulnerability site and take appropriate remedial effort to protect the pristine island coastal ecosystem.