DISSOLVED AND PARTICULATE TRACE-METALS IN THE COCHIN ESTUARY

The Cochin estuary located at 9-degrees-58'N latitude and 76-degrees-15'E longitude is subjected to various types of effluents discharged from the Eloor and Chitrapuzha industrial belts. The present study reports the concentrations of dissolved and particulate copper, zinc, cadmium, lead, nickel, and iron based on three consecutive surveys conducted during July (monsoon), November (post-monsoon) 1985 and April (premonsoon) 1986. The concentrations of dissolved and particulate copper, zinc and cadmium showed high seasonal variation. Seasonal variation in the concentrations of nickel and lead was negligible. Iron was found to be removed from the dissolved state. Surface water samples contained higher concentrations as compared to the bottom. The study revealed that salinity plays an important role in the precipitation of particulate matter and heavy metals with respect to estuarine mixing.