Zinc is one of the biologically significant elements and is known to occur in sea water only in sub-micromolar concentrations. Though zinc concentrations in some off-shore locations in Indian Ocean have been reported the distribution pattern of zinc in marine waters, organisms and sediments have not been studied in coastal waters and estuaries. This assumes importance in such areas because of the possible larger exchange of elements between sediments and waters.

The paper reports results of the study conducted in the estuarine environment of the Bombay Harbour Bay. Sea water, marine organisms and sediments collected from different locations in the bay were analysed for zinc content. Dithizone in carbon tetrachloride was used for extracting zinc from sea water; marine organisms and sediments were processed prior to removal of interfering elements, final extraction of zinc and subsequent spetrophotometric measurements. Detailed standardisation of the method followed was carried out and care was taken to eliminate possible contamination from apparatus used in order to get reliable data. AH reagents used were tested for zinc contamination and the reagents purified wherever necessary.

The results indicate wide variations in the concentration of zinc in all constituents of the bay. Sea waters in the bay had zinc concentrations varying from 2.65-33.92 -µg/l. Suspended silt and bottom sediments had high concentration of zinc but shore sediments showed relatively lower values. There was no correlation between loss on ignition and or oxidisable carbon in sediments and the zinc content. Of the organisms studied barnacles and crab showed high concentration factors for zinc.