Caracterização biogeoquímica do fluxo de nutrientes, em relação aos processos oceanográficos no Estuário do Rio Incomati, durante a estação seca

Abstract

The Incomati River is one of the international rivers that flows through Mozambican territory and flows into the northern part of Maputo Bay. During its journey, it transports various types of nutrients that contribute to increase the productivity of the estuary and the Maputo Bay, whose resources support the lives of many fishing families and earn about 3.5 million US dollars to the country. As a result of the interaction of the waters of the Incomati River and the Maputo Bay, the main nutrients namely, ammonia, phosphate, nitrate and silica to those exported from the estuary to the bay. This conclusion was proven through direct observation and modeling (One box model), through the understanding of the physical oceanographic parameters that govern the transport and distribution of these nutrients in the estuarine water column. This understanding was also made through the identification of the main sources of the mentioned nutrients and their qualification in the course of the tides, during the transitional period from high tide to dead tide, in the dry season of September. The results of this study show that the Incomati River is the main source of phosphate silica, with mangroves being the main sources of ammonia. Temperature and salinity are of little importance in the flow of these nutrients. The energy of the tides and winds are relevant in the flow, because they contribute to the process of mixing the waters of the river and the bay, in such a way that the transport and distribution of ammonia, phosphate, nitrate and silica, are governed by the processes of turbulent diffusion . These results are relevant because they launch the platform for the investigation of the impact of human activities in a hydrographic basin on adjacent coastal resources, as well as the understanding of various ecological, physical, and biogeochemical processes in the Maputo bay and estuary, which will contribute to the management sustainable use of its resources.