2017-04-172017-04-172002-11-22MELO, Odilon Teixeira de. Dinâmica de nutrientes e da matéria orgânica no manguezal do Igarapé Nunca Mais - Ilha de São Luís (MA). Orientador: Waterloo Napoleão de Lima. 2002. 150 f. Tese (Doutorado em Geologia e Geoquímica) - Centro de Geociências, Universidade Federal do Pará, Belém, 2002. Disponível em: http://repositorio.ufpa.br:8080/jspui/handle/2011/8171. Acesso em:.https://repositorio.ufpa.br/handle/2011/8171It is well known that the State of Maranhão has more than fourty percent of the Brazilian mangroves covering an área with almost 4800km2 and along of 640km of coastline. These mangrove swamps border a number of tidal channels, bays, gulfs, and others estuarine systems, where the macro-tidal system gives a singular condition to this environment, that it is different from the others Brazilian áreas. The exportation of macro-particles from the mangroves to the coastal waters is well known. However, there is a discussion if the mangroves import or export micro-particles and dissolved nutrients to the coastal areas. Few studies have been developed in this subject due to the methodological complexities of the flow calculations. The choice of the pilot-area for this study is the igarapé Nunca Mais, a tidal channel surrounded by an area of 1.22km2 of mangrove ecosystem, situated in the Northeastern portion of the São Luís Island. This choice is due bay the fact that in this area occurs exchanges with the coastal waters from the Maranhão Gulf take place. This tidal channel is the main transport pathway between the mangrove and the coastal waters. During the spring tides this mangrove is completly flooded. The main aim of this study was to evaluate the role of a mangrove region — Maranhão Gulf — in a macro-tidal area in exchanging of materials with the coastal waters. The characterization and quantification of the dissolved inorganic nutrients and the organic matter were the main focuses of this study. For this purpose were utilized flows calculations from "Eulerian" method. During the period of 13 months (from April 2000 to April 2001), in the neap and spring fluxes of the dissolved inorganic nutrients (ammonium, nitrite, nitrate, phosphate, and silicate) and those of the organic matter (organic carbon, organic nitrogen, and organic phosphorus) were determined along 52 tidal cycles. For the characterization of organic matter were used elemental ratio C/N, isotopes 13C and 15N ratio, and by the identification of dissolved humic substances as tracers for organic matter sources. The differences on day clear and orvernight show average values from 0960 for the pH and salinity, positive values of 5, 6, 8 and 11%, respectively, for nitrate, phosphate, ammonium, and silicate, and negative values for the oxygen (-10%), and for the dissolved and particulate organic matter (-1% to -6%). The dissolved nutrients and organic matter varies such as tidal ranges showing maximum values in the low tile, indicating flow from intersticial water of the mangrove for the tidal channel. Particulate organic matter values show variations relationships with current velocity showing resuspension and sediment transport. This fact confirms that the biological processes, such as nutrient consumption and organic matter deposition, in the tidal channel, and the tidal dynamics were relevants in the lief variations. The results obtained in this study show a seasonal variation with minium values in the dry season, except for the silicate, and maximum values in the rainy season, showing the raro precipitation influence in the transport from mangrove for the coastal waters. In addition, in the dry period, occurs maximum consumption of nutrient by phytoplancton, as well as, observed on primary production. It was evidencied also lower values in the concentration of particulate organic matter during this dry season due the lower fluxes values from the mangrove. The net exportation of inorganic nutrients and the organic matter in the mangroves of the São Luís Island (Maranhão State, Brazil), in the tidal channel Igarapé Nunca Mais, is evidencied in this study by interpretation of the flows calculations and the values from C/N. rations, elemental and isotopic. The isotopes of C and N used here as tracers lead to the identification of the primary sources of the organic matter in the tidal channel, i.e., the originated from mangroves, the coastal waters, and the resulting from allochthonous production. During the rainy period there are dominance of the organic matter (dissolved and particulate) transported from the mangrove, while in the dry period the marine and autochthonous sources are more considerables. The photosynthesis of the phytoplancton, in the tidal channel, justifies the autochthonous production. The net exportation of the dissolved organic matter for the coastal waters is slightly superior to the particulate organic matter (DOM, 14mM-2.day-1; POM, 20mM.m.-2.day-1). Perhaps this difference is due a fast sedimentation in the intermediary zune of the tidal channel that have the biggest profundity; this fact leads a minor quantity of particulates exported for coastal waters. It infers that this organic matter is constititued, dominantly, by humic substances because they are more refractory to the bacterial activity and consequently they can be transported by tidal currents for the adjacent coastal waters. Of course, the tidal amplitude ranges and pluviometric precipitation are relevant factors in these exportation processes. By this exposition, this study confirms the important role of mangrove for the fertilization of the coastal waters of Maranhão Gulf.Acesso AbertoBiogeoquímicaEcologia dos manguezaisNutrientesMatéria orgânicaMangueIgarapé Nunca Mais - MAIlha de São Luis - MATeseCNPQ::CIENCIAS EXATAS E DA TERRA::OCEANOGRAFIA::OCEANOGRAFIA QUIMICA::INTERACOES QUIMICO-BIOLOGICAS/GEOLOGICAS DAS SUBSTANCIAS QUIMICAS DA AGUA DO MAR