Understanding sedimentary depositional environments through geochemical signatures of a Tropical (Vaghotan) estuary, West Coast of India

Abstract

Two sediment cores collected from intertidal mudflats of the main estuarine channel and adjoining subchannel from Vaghotan Estuary, West Coast of India, were studied to understand the depositional environment, sources and enrichment of metals and their toxicity. Sediment components and metal associations suggest that main channel and sub-channel sediment properties varied owing to differential sediment supply and processes. The subchannel sediments tend to accumulate higher metal concentrations facilitated by sheltered and calm sedimentary environment. Main channel sediments, however, are subjected to relatively higher energy conditions due to tidal flushing which caused re-suspension and transfer of finer sediments to places of less energy environments retaining higher coarser sediments. Results also showed that the metals in lower sections of the two cores were mainly from a lithogenic source whereas the upper sections indicated an anthropogenic influence in recent times. Pollution indices indicated contamination of sediments by metal in recent times due to enhanced human induced activities in the catchment area and concentration of Co in the mudflat sediments pose a higher risk to biota in sub-channel mudflats than the main channel.