Mercury in Thana Creek,Bombay Harbour

Mercury content of the water column estimated along Thana Creek/Bombay Harbour gave a standing stock of about 77 kg in excess of the expected background. Mercury concentration in sediment from 23 locations which varied from 0.17 to 8.21 ppm (dry weight) with marked increase from the harbour to the creek region suggests substantial mercury input in the head region. Chemical extraction by hydrogen peroxide indicated that more than 70% of mercury was leachable and probably organically bound. The mercury enriched layer in the sediment cores was about 10–25 cm in the creek region and 0–8 cm in the harbour area. The data has been used to calculate an excess of 14 tonnes of mercury over the natural background. Analysis of a few zooplankton and benthic samples from the creek region gave indication of bioaccumulation of mercury.