Navegando por Autor "SANTOS, Maria de Lourdes Souza"

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Acesso aberto (Open Access)
An analysis of total phosphorus dispersion in lake used as a municipal water supply
(Academia Brasileira de Ciências, 2015-09) LIMA, Romulo Correa; MESQUITA, André Luiz Amarante; BLANCO, Claudio José Cavalcante; SANTOS, Maria de Lourdes Souza; SECRETAN, Yves
In Belém city is located the potable water supply system of its metropolitan area, which includes, in addition to this city, four more municipalities. In this water supply complex is the Água Preta lake, which serves as a reservoir for the water pumped from the Guamá river. Due to the great importance of this lake for this system, several works have been devoted to its study, from the monitoring of the quality of its waters to its hydrodynamic modeling. This paper presents the results obtained by computer simulation of the phosphorus dispersion within this reservoir by the numerical solution of two-dimensional equation of advection-diffusion-reaction by the method θ/SUPG. Comparing these results with data concentration of total phosphorus collected from November 2008 to October 2009 and from satellite photos show that the biggest polluters of the water of this lake are the domestic sewage dumps from the population living in its vicinity. The results obtained indicate the need for more information for more precise quantitative analysis. However, they show that the phosphorus brought by the Guamá river water is consumed in an area adjacent to the canal that carries this water into the lake. Phosphorus deposits in the lake bottom should be monitored to verify their behavior, thus preventing the quality of water maintained therein.
Acesso aberto (Open Access)
Estudo das diferentes formas de fósforo nas águas da plataforma continental do Amazonas
(2007-06) SANTOS, Maria de Lourdes Souza; COSTA, Katia Muniz Pereira da; FEITOSA, Fernando Antonio do Nascimento; BARROS NETO, Benício de
Hydrological samples were collected on the continental shelf of the Amazon river to determine particulate organic and inorganic matter, dissolved organic phosphorus (DOP), phosphate, total particulate phosphorus (TPP), chlorophyll a, temperature, salinity, pH, water transparency, dissolved oxygen (DO) and saturation rate. The objective was to study the forms of DOP, phosphate and TPP. In the euphotic layer, the fluvial discharge from the Amazon river favored the distribution of phosphate, TPP and DOP. In the aphotic layer, the phosphate concentration increased due to the decomposition of DOP and TPP. This increase is due to the absence of photosynthetic processes.
Acesso aberto (Open Access)
Nutrient and phytoplankton biomass in the Amazon River shelf waters
(2008-12) SANTOS, Maria de Lourdes Souza; MUNIZ, Kátia; BARROS NETO, Benício de; ARAUJO, Moacyr Cunha
The Amazon River estuary is notable at the Amazon Continental Shelf, where the presence of the large amount of water originating from the Amazon during the river's falling discharge period was made evident by the low salinity values and high nutrient levels. Even so, the presence of oceanic waters in the shelf area was significant. Dissolved organic nitrogen was the predominant species of the nitrogen cycle phases, followed by total particulate nitrogen, nitrate, ammonium and nitrite. The chlorophyll a data in the eutrophic area indicated that there is sufficient nitrogen in the area to withstand productivity, though dissolved inorganic nitrogen removal processes are faster than regeneration or mineralization. The anomalous amounts of inorganic dissolved nitrogen showed more removal than addition. The simulations with the bidimensional MAAC-2D model confirmed that high nutrient waters are displaced northwest-ward (two cores at 2.5ºN-50ºW and 4ºN-51ºW) by the stronger NBC during falling river discharge. During high river flow period these nutrient-rich lenses are distributed around 0.5ºN-48.5ºW as well as along the shallow Amazonian shelf (20m-50m depth, 1ºN-3.5ºN), as a result of the spreading of Amazon freshwater outflow.
Acesso aberto (Open Access)
Observações hidrológicas e resultados de modelagem no espalhamento sazonal e espacial da pluma de água Amazônica
(Instituto Nacional de Pesquisas da Amazônia, 2009) SILVA, Alex Costa da; SANTOS, Maria de Lourdes Souza; ARAUJO, Moacyr Cunha; BOURLÈS, Bernard
In this study, we present surface synoptic data collected during four oceanographic cruises undertaken in March-April 1995, October-November 1997, April-May 1999 and August-September 2001 in the Brazilian Program “REVIZEE/SCORE-NO” and a combination of model results (1/6 deg.). The emphasis of this paper is to point out the monthly changes on the spreading of the Amazon plume over the external Amazon shelf area and the eastern region of the Amazon River. Hydrographic data and model results demonstrated that during March-May, the Amazon plume moved southwestward along the northern coast of Brazil, decreasing during August-September; but this was not observed during October-November. Model results revealed ring signatures shedding from the North Brazil Current (NBC). Results also showed that during August the Amazon plume encircling the NBC retroflection was around 7º N.
Acesso aberto (Open Access)
Qualidade das águas superficiais e avaliação do estado trófico do Rio Arari (Ilha de Marajó, norte do Brasil)
(Instituto Nacional de Pesquisas da Amazônia, 2012-03) ALVES, Igor Charles Castor; EL-ROBRINI, Maâmar; SANTOS, Maria de Lourdes Souza; MONTEIRO, Sury de Moura; BARBOSA, Leandro Patrick Ferreira; GUIMARÃES, José Tasso Felix
The deterioration of the water quality may be caused either by the result of human pressure on aquatic environments in larger scales, or by natural factors in smaller scales, such as part of the Arari River basin (Marajó Island, Pará state, Brazil) .This work aimed to evaluate the surface water's quality and the trophic state of the Arari River, between Santana and Cachoeira do Arari localities, taking into account the seasonal and spatial variations of physical, chemical and biological parameters in two different hydrological periods in 2009: the maximum discharge (April to May) and minimum discharge (September to November). The Water Quality Index (WQI) and Trophic State Index (TSI) were determined simultaneously in water surface's samples collected during 12 consecutive hours in three stations along the Arari River. The WQI data ranged from "Poor" and "Regular" and are probably related to the high levels of fecal coliform, low concentrations of dissolved oxygen and acid pH of the Arari River. Regards the TSI, the river may be classified as "supereutrophic" and "hipereutrophic", indicating the wide availability of nutrients (e.g. phosphorus) and high phytoplankton biomass in terms of chlorophyll a content. The Arari River is under a natural eutrophication, since the sources of anthropic contamination are still incipient, although they may contribute to the long-term process of artificial eutrophication.