Trace metals in a tropical river environment-distribution

Distribution of trace metals in the Periyar river has been investigated in detail. The fluvial concentrations of trace metals increase in river water and decrease in sediments during the summer months due to solubilization and concentration by evaporation. The levels, especially of Zn and Cd which are industrial pollutants increase by a factor of 10 both in water and sediments at the industrial zone. The concentration of Cd in the river water approaches the WHO standards for safe limits in drinking water. Solubilization at the backwater zone under high salinity is identified as one of the major mechanisms of trace metal transport to the marine environment. River meandering is responsible for large scale deposition of suspended solids at the industrial zone during the monsoon period. The trace metals exhibit build-up in specific concentration in the suspended solids in proportion to their residence time.