Assessment of metal contamination in a tropical estuary, West Coast of India

In this study, we report an assessment of metal (Fe, Mn, Zn, Cr, Cu and Pb) contamination in surface sediments of a tropical estuary from Goa-the West coast of India. Surface sediment samples were collected along the 35 km stretch of the Zuari estuary on monthly basis for a period of 1 year and samples were analyzed for texture, organic carbon (OC) and metals. Seasonal variation of metals did not show any significant variation, except for Zn and Pb in the present study. Spatial variation of metals was influenced by sediment texture, OC and land runoff. The contamination factor and Geo-accumulation index (I Geo) revealed moderate contamination of Pb and Cr. Factor analyses suggest role of Fe–Mn oxy-hydroxide, OC and textural variables in abundance of trace metals in the sediments. Further, an attempt was made to understand the impact of mining on the Zuari estuary by comparing the present data (during mining ban period) with earlier published reports (during extensive mining period). It revealed influence of mining on the concentrations of Fe and Mn in surface sediments, but had no impact on the concentration of Cu, Cr, Zn and Pb in the Zuari estuary.