Spatial Distribution of Trace Element into a Fluvial Urban System in Chennai, India

Abstract

The present study was conducted to investigate the trace element contamination of urban river sediments of the Adyar and Cooum River, Chennai, Tamil Nadu, India. Both are the major source of urban irrigation and water supply system. An intensive sampling and analysis of bed sediments and flood deposits is done to find out the sources and transfer of trace elements across the river stream. The bed sediments and flood deposit samples were collected from 19 different stations along the course of both rivers using standard sampling methods and concentrations of multi trace elements were determined on the less than 63 µm fraction. Grain size analysis was performed on fresh bulk sediments using a laser diffraction microgranulometer Mastersizer 3000, Grain size analysis reveals that Adyar River and Cooum river consists of coarse sand, silt and clay. It is also found that the trace elements are linked with organic sediment matrix. Concentrations of total carbon (TC) content in the Adyar River range between 3.1% to 26.4% and 8.0 % to 27.2% in the Cooum River respectively. Trace element concentrations are asses with the geoaccumulation index (Igeo), results indicate that the river basin is moderately to extremely polluted. Especially Ag, Cd and Hg are present at alarming level and use as Urban tracer. This may be ascertained to the various pollutants discharge via diffuse urban and punctual industrial sources operating in and around the river bed. It was concluded that the sediment in the Adyar and Cooum rivers were severely polluted and should be monitored of different pollutants adversely affecting the environment.