Spatial distribution and enrichment of heavy metals in nearshore surface sediments off Netravati–Uppala, southwestern India

Abstract

Offshore surface sediments were collected along the south Karnataka coast of India, from the Netravati River mouth to Manjeshwar, to investigate the spatial distribution of metals. Average concentration of the metals in the 90 km² area followed the order Cd < Pb < Co < Cu < Ni < Zn < Cr < Sr < Mn < Mg < Ti < Ca < Fe < Al. Trace metal contamination levels were assessed using various pollution indices, indicating that Mn, Ni, Cu, and Zn do not show significant contamination, whereas Cr exhibits moderate contamination in the study area. Areas around the mouth of the Netravati River and distant from the shore are considered polluted, as indicated by the Pollution Load Index (PLI), which is greater than 1. A close relationship between Cr and river-laden sediments indicates that the Netravati River is bringing Cr, an enriched element, to the study area.