Study of the nutrients in the adjacent pelagic environment to the coast of Pará State

Abstract

The present work was accomplished with data of the Program “Evaluation of the Sustainable Potential of the Living Resources of the Economic Exclusive Zone”, obtained during the North Operation III (1999). The objective was to study the horizontal and vertical distribution of the nitrate, nitrite, ammonia, phosphate and silicate in 48 oceanographic stations, and to relate with the temperature (T), the salinity (S), the dissolved oxygen (OD) and the tax of saturation of dissolved oxygen (% OD). In cruise were obtained T, S, OD, %OD data and the Secchi disk used to identify the euphotic and aphotic layers. For the determination of the nutrients, the samples were maintained in freezer for subsequent analysis in the laboratory. EEZ North’s pelagic environment was presented oceanic characteristics, however, close of the coastal area the fluvial influence was verified, through the largest values of the superficial distribution of nitrate, phosphate and silicate. In the euphotic layer, the distributions of the nutrients (except the nitrite that had an irregular distribution) presented smaller values. However, an increasing was verified in the concentration of those nutrients in the layer aphotic, related to the process of degradation of the organic matter that liberates them again for the column of water.