Chemical oceanographic studies on the Bay of Bengal - North of Visakhapatnam

Abstract

Data on hydrography, nutrients, fluoride, primary productivity and trace metals were obtained from 16 stations during the 128 cruise of R.V. Gaveshani in Bay of Bengal - North of Visakhapatnam. The mixed surface layer (0-50m) was associated with high dissolved oxygen and low nutricnt concentrations. The intermediate layer (100-500m) was marked by a steep raise in nutrient concentration and oxygen minimum indicating an active zone of decomposition of organic matter. N:P ratio in the upper 100m was considerably lower than that in the depth range of 1000-2000m where it was almost constant (6.0 to 7.0). The overall concentration of fluoride and F/Cl ratio obtained in the present study are some what lower than those reported (could be attributed to the dilution and removal of F by settling particles). Primary productivity was relatively lower than reported earlier for the Bay of Bengal which was attributed to the seasonal changes in productivity.