TRACE-ELEMENT GEOCHEMISTRY OF MODERN SEDIMENTS OF THE VELLAR RIVER AND ITS SURROUNDING ENVIRONMENTS

Organic carbon (C-org), carbonate (Carb), major (Al, Fe, Mn, Ti) and t race (Cu, Co, Ni, Zn, Cd, Cr) elements concentration were determined i n both bulk samples and clay (<2 mu size) fractions of sediments colle cted from 31 selected stations in the Vellar river (6), its estuary (1 0) and nearshore (15) environments. Bulk sediments in riverine environ ments show lowest in concentration and estuarine shows the highest con centration in all elements except Ti, Mn and Cr. Ti concentration is m ore in the riverine sediments and Mn concentration lowest in the nears hore sediments. In the case of Cr all the environments reveal almost s ame amount. Clay fraction in estuarine environment shows lowest concen tration of Fe, Mn, Cu, Ni, Zn and Co. Nearshore environment exhibits h ighest 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 conce ntration in riverine environment. Cd and Cr are distributed in almost equal amount in all the environments. Based on the interpretation of t he data and R-mode factor analysis suggested that distribution of the above chemical constituents are mainly influenced by differential comb ination of factors such as grain size variation; Fe and Mn precipitati on; composition of the mineralogy of the sediments; and desorption of elements from the precipitates.