Data on the distribution of trace elements viz., iron, copper, manganese and cobalt incorporated in this paper deals with values obtained in the inshore waters of the Bay of Bengal off the coast of Waltair for a period of two years (1961 to 1962)and also from different regions of the Bay of Bengal obtained during March-April 1963 on board R. V. ANTON BRUUN during the International Indian Ocean Expedition.

Surface average values of iron, copper and manganese exhibit a seasonal variation from high values ranging from 72-104µg/l in August for iron, 19.5-21 µg/1 in October-November for copper and 13-17 fish in August for manganese to low values ranging from 15.2-26.5 µg/l in March-April for iron, 15.8-6.8 µg/1 for copperin April, and 1.5-2.2 µg/l in April for manganese. Cobalt shows a small variation from OAA/µg/l in August to 0.28 µg/l in March April in 1961 and 0.38 µg/l in July too.24fig/l in April in 1962. High values of iron, copper, manganese and cobalt are attributed to contribution from rivers and storm water channels draining the areas of mineral deposits located north of Waltair during the south-west monsoon period. Low values of these four elements during March-April period suggest utilisation by the phytoplankton crop.

Average values of iron, copper, and manganese in the surface water of the different regions of the Bay of Bengal reveal only a slight variation during March-April 1963 and show a tendency to increase in a south to north direction from the Nicobar Sea towards the head of the Bay. The concentrations are higher near the coasts and lower in the oceanic areas. The vertical distribution reveals that iron and copper content is generally high in surface water and decreases with depth up to 500 metres after which the content shows a rise at 1000 metres.