Trace element geochemistry of modern sediments of the Vellar river and its surrounding environments

Abstract

Organic carbon (C-org), carbonate (Carb), major (Al, Fe, Mn, Ti) and trace (Cu, Co, Ni, Zn, Cd, Cr) elements concentration were determined in both bulk samples and clay (<2 mu size) fractions of sediments collected from 31 selected stations in the Vellar river (6), its estuary (10) and nearshore (15) environments. Bulk sediments in riverine environments show lowest in concentration and estuarine shows the highest concentration in all elements except Ti, Mn and Cr. Ti concentration is more in the riverine sediments and Mn concentration lowest in the nearshore sediments. In the case of Cr all the environments reveal almost same amount. Clay fraction in estuarine environment shows lowest concentration of Fe, Mn, Cu, Ni, Zn and Co. Nearshore environment exhibits highest concentration of C-org, Carb, Fe, Mn, Cu, Zn and Co. C-org and Carb show lowest concentration and Al, Ti and Ni display highest concentration in riverine environment. Cd and Cr are distributed in almost equal amount in all the environments. Based on the interpretation of the data and R-mode factor analysis suggested that distribution of the above chemical constituents are mainly influenced by differential combination of factors such as grain size variation; Fe and Mn precipitation; composition of the mineralogy of the sediments; and desorption of elements from the precipitates.