Chemical oceanography of the Indian Ocean, North of the equator

Abstract

Chemical oceanographic studies in the North Indian Ocean have revealed several interesting and unique features. Dissolved oxygen northern boundary, prevents quick renewal of subsurface reducing conditions prevail at intermediate depths (ca. 150-1200m) resulting in the reduction of nitrate (denitrification). The North Indian Ocean may contribute up to 10% of the global marine denitrification. The "denitrified" nitrogen, when combined with the rate of photo synthetic production reaching below the euphotic zone, gives the average residence time the subsurface layers are very high in close proximity of the euphotic zone, gives the average residence time of water between 75 and 1200m as 43-51d years. The inorganic nutrient concentrations in the subsurface layers are very high in close proximity of the euphotic zone