Some aspects of nutrient chemistry of the Caribbean Sea

Abstract

Chemical oceanographic studies were conducted at 45 stations in the Caribbean Sea, covering both nearshore and offshore areas. The concentrations of oxygen in the upper mixed layers varied between 180 and 220 mu mol.dm sup(-3) and the subsurface waters showed a decrease up to 110 mu mol.dm sup(-3) at around 400 m. Within the euphotic zone considerable amounts of oxygen (30-60 mu mol.dm sup(-3)) were utilized for organic matter degradation, even within the euphotic zone. Two nitrate maxima, one representing nitrite excretion/organic matter oxidation and another due to nitrate reduction, were observed. Phosphate and nitrate levels were low in the upper 60 m and showed an increase with depth due to regeneration processes. Salinity - nutrient oxygen relations and silicate and density relations revealed surface, subtropical subsurface and subantarctic water mass signatures in the upper 500 m