Distribution of sediment components and metals in recent sediments within tidal flats along Mandovi estuary

Abstract

Three short sediment cores from locations namely Betim representing lower estuarine region; Karyabhat - lower middle estuarine region and Ribander - upper middle estuarine region were collected from intertidal regions of the Mandovi estuary along west coast of India. The cores were subjected to sedimentological and geochemical analyses in order to understand the sediment texture, organic matter content and metal distributitin (Fe, Mn, Cr, Cu, Co, Ni, Zn, Pb and Al) in the sediments with depth along the estuary. Results indicated that the sediments along the lower estuarine region were mainly coin-posed of coarser sediments with less organic matter, whereas in the middle.region finer sediments. with high organic matter were deposited. Isocon diagram clearly indicated that most of the metals were deposited more towards the lower middle estuarine region when compared to other two locations. Calm environmental conditions must have facilitated deposition of finer sediments associated with high concentration of metals at Karyabhat. Role of sediment size, organic matter concentration and Fe-Mn oxy-hydroxides in distribution of trace metals down the core are discussed.