Balanço de energia e fluxos turbulentos associados à fatores físico-químicos da água na baía de Caxiuanã

Investigar o comportamento do balanço de energia sobre superfícies aquáticas ainda é um desafio cientifico, pois são raros estudos disponíveis neste tipo de superfície. A flona de Caxiuanã há vários anos se tornou um grande objeto de estudo para diversos ramos da ciência, que servem de suporte para região amazônica. Dentre esses encontra-se a micrometeorologia, que aborda entre seus principais tópicos de interesse os fenômenos de troca de energia e massa na interface superfície-atmosfera. Visando suprir essa carência de informações, no presente estudo foram analisadas as variações horárias e sazonais das componentes do balanço de energia, como fluxo de calor latente e de calor sensível. Com o auxilio de variáveis meteorológicas tais como precipitação, temperatura do ar, velocidade e direção do vento além de parâmetros físico-químicos da água (albedo, nível de maré, turbidez, temperatura da água, carbono orgânico e inorgânico total) verificou-se o papel de cada uma dessas variáveis no fechamento do balanço de energia sobre uma superfície aquática na baia de Caxiuanã. Uma peculiaridade apresentada pela baia de Caxiuanã foi a temperatura da água estar sempre com valores superiores à temperatura do ar, demonstrando que a baia consegue reter grande quantidade de calor durante o dia, e não perde a maior parte deste calor para a atmosfera durante a noite. O carbono orgânico total presente nas águas da baia apresentou redução da concentração ao longo do período de estudo. O fluxo de calor latente (LE) mostrou ser a componente dominante do balanço de energia, apresentando valor médio de 200 W.m^-2 durante a maior parte do período de estudo, e o fluxo de calor sensível (H) apresentou valor máximo em Maio, cerca de 50 W.m^-2. Os valores negativos de H durante período noturno demonstram que a baia está perdendo calor para o ambiente, isto é, a mesma esta atuando como fonte calor para atmosfera adjacente, inclusive para a floresta.

Dinâmica sazonal de nutrientes em estuário amazônico

Este artigo mostra a distribuição dos nutrientes no estuário do rio Paracauari, durante um ciclo hidrológico amazônico (2008), e no final do período de La Niña (abril de 2008). Esse estuário é influenciado por clima tropical úmido e meso-marés (3 a 4m), semi-diurna. A amostragem foi realizada em 10 estações em três períodos sazonais distintos: chuvoso (março), intermediário (junho) e menos chuvoso (setembro). Medimos “in situ” os parâmetros físico-químicos utilizando uma sonda multiparâmetro; analisamos os nutrientes dissolvidos (nitrato, nitrito, n-amoniacal, fosfato e silicato) por espectofotometria e o material particulado em suspensão por gravimetria. Observamos amplas variações sazonais nas concentrações dos parâmetros estudados. A temperatura da água (média de 28,58 ºC) é bastante homogênea, típica das águas tropicais. O pH variou de ácido (5,80) à alcalino (7,86) e a salinidade entre 0,06 a 7,56 ambos com valores máximos na foz, devido à maior influência marinha. As águas são mal oxigenadas no período chuvoso (2,35 mg.L-1) e bem no menos chuvoso (6,55 mg.L-1). As concentrações de material particulado em suspensão e de nutrientes foram máximas no período chuvoso devido ao aporte natural proveniente das áreas adjacentes.

Atributos populacionais e produtividade secundária de rotíferos em ambientes lacustres naturais e artificiais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Contributions of the old urban homegardens for food production and consumption in Rio Claro, Southeastern Brazil

Urban homegardens are green areas of households within the city limits and they have the potential to provide families with a cheap alternative for diet improvement, and to complement the income of the families who sell cultivated products. This research analyzes the contributions of old urban homegardens on food consumption and household economy. Data related to homegardens composition were collected by interviews and by collecting cultivated plants. Diets were assessed through a retrospective method (last 24 hours food recall) and administered every two months, during a year, to include seasonal variations. The diet of the sampled population was found to be dependent on certain foods, indicating a narrow food niche (Levins index = 25.9; Levins standardized index = 0.23). Variations in interviewees' diet are related to the consumption of fruits and vegetables, which are partly supplied by homegardens. Spices and teas consumed were obtained from homegardens, revealing its importance in food consumption and health. Among the 98 species found in homegardens, only 38% appeared in the interviewees' diet, indicating an under-exploitation of these homegardens. Our study found that the main role of homegardens is to supply variation in the diet, contributing to the consumption of different types of products.

Spatial-temporal variation of parasites in Cnemidophorus ocellifer (Teiidae) and Tropidurus hispidus and Tropidurus semitaeniatus (Tropiduridae) from Caatinga areas in northeastern Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ecological competition and the incidence of Acinetobacter baumannii bloodstream infections in a teaching hospital in Southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Feeding, body condition and reproductive investment of Astyanax intermedius (Characiformes, Characidae) in relation to rainfall and temperature in a Brazilian Atlantic Forest stream

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Diurnal and annual evolution of UV, PAR and NIR irradiations in Botucatu/Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modelagem dos níveis freáticos do sistema aquífero Bauru (SAB) em diferentes usos da terra no município de Assis - SP

Pós-graduação em Agronomia (Irrigação e Drenagem) - FCA

Sazonalidade climática e os efeitos na helmintofauna parasita de Dendropsophus nanus (Anura: Hylidae) da RPPN Foz do rio Aguapeí, município de Castilho, São Paulo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da distribuição de tamanho e composição iônica de aerossóis e seus efeitos na capacidade de nuclear gotas de nuvens

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Monitoramento da composição isotópica e físico-química da água de chuva no município de Rio Claro (SP)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phytoplankton Dynamics in Three Rocky Mountain Lakes, Colorado, U.S.A.

In 1984 and 1985 seasonal changes in phytoplankton were studied in a system of three lakes in Loch Vale, Rocky Mountain National Park, Colorado. Three periods were evident: (1) A spring bloom, during snowmelt, of the planktonic diatom Asterionella Formosa, (2) a mid- summer period of minimal algal abundance, and (3) a fall bloom of the blue-green alga Oscillatoria limnetica. Seasonal phytoplankton dynamics in these lakes are controlled partially by the rapid flushing rate during snowmelt and the transport of phytoplankton from the highest lake to the lower lakes by the stream, Icy Brook. During snowmelt, the A. formosa population in the most downstream lake has a net rate of increase of 0.34 d-1, which is calculated from the flushing rate and from the A. formosa abundance in the inflow from the upstream lake and in the downstream lake. Measurement of photosynthetic rates at different depths during the three periods confirmed the rapid growth of A. formosa during the spring. The decline in A. formosa after snowmelt may be related to grazing by developing zooplankton populations. The possible importance of the seasonal variations in nitrate concentrations were evaluated in situ enrichment experiments. For A. formosa and O. limnetica populations, growth stimulation resulted from 8- or 16-micromolar amendments of calcium nitrate and sulfuric acid, but the reason for this stimulation could not be determined from these experiments.

Variability of the subtropical shelf front off eastern South America: Winter 2003 and summer 2004

Hydrographic data collected during surveys carried out in austral winter 2003 and summer 2004 are used to analyze the distributions of temperature (T) and salinity (S) over the continental shelf and slope of eastern South America between 27 degrees S and 39 degrees S. The water mass structure and the characteristics of the transition between subantarctic and subtropical shelf water (STSW), referred to as the subtropical shelf front (STSF), as revealed by the vertical structure of temperature and salinity are discussed. During both surveys, the front intensifies downward and extends southwestward from the near coastal zone at 33 degrees S to the shelf break at 36 degrees S. In austral winter subantarctic shelf water (SASW), derived from the northern Patagonia shelf, forms a vertically coherent cold wedge of low salinity waters that locally separate the outer shelf STSW from the fresher inner shelf Plata Plume Water (PPW) derived from the Rio de la Plata. Winter T-S diagrams and cross-shelf T and S distributions indicate that mixtures of PPW and tropical water only occur beyond the northernmost extent of pure SASW, and form STSW and an inverted thermocline characteristic of this region. In summer 2004, dilution of Tropical water (TW) occurs at two distinct levels: a warm near surface layer, associated to PPW-TW mixtures, similar to but significantly warmer than winter STSW, and a colder (T similar to 16 degrees C) salinity minimum layer at 40-50 m depth, created by SASW-STSW mixtures across the STSF. In winter, the salinity distribution controls the density structure creating a cross-shore density gradient, which prevents isopycnal mixing across the STSF. Temperature stratification in summer induces a sharp pycnocline providing cross-shelf isopycnal connections across the STSF. Cooling and freshening of the upper layer observed at stations collected along the western edge of the Brazil Current suggest offshore export of shelf waters. Low T and S filaments, evident along the shelf break in the winter data, suggest that submesoscale eddies may enhance the property exchange across the shelf break. These observations suggest that as the subsurface shelf waters converge at the STSF, they flow southward along the front and are expelled offshore, primarily along the front axis. (C) 2008 Elsevier Ltd. All rights reserved.

Coastal and shelf circulation in the vicinity of Camamu Bay (14 degrees S), Eastern Brazilian Shelf

The Camamu Bay (CMB) is located on the narrowest shelf along the South American coastline and close to the formation of two major Western Boundary Currents (WBC), the Brazil/North Brazil Current (BC/NBC). These WBC flow close to the shelf break/slope region and are expected to interact with the shelf currents due to the narrowness of the shelf. The shelf circulation is investigated in terms of current variability based on an original data set covering the 2002-2003 austral summer and the 2003 austral autumn. The Results show that the currents at the shelf are mainly wind driven, experiencing a complete reversal between seasons due to a similar change in the wind field. Currents at the inner-shelf have a polarized nature, with the alongshore velocity mostly driven by forcings at the sub-inertial frequency band and the cross-shore velocity mainly supra-inertially forced, with the tidal currents playing an important role at this direction. The contribution of the forcing mechanisms at the mid-shelf changes between seasons. During the summer, forcings in the two frequency bands are important to drive the currents with a similar contribution of the tidal currents. On the other hand, during the autumn season, the alongshore velocity is mostly driven by sub-inertial forcings and tidally driven currents still remain important in both directions. Moreover, during the autumn when the stratification is weaker, the response of the shelf currents to the wind forcing presents a barotropic signature. The meso-scale processes related to the WBC flowing at the shelf/slope region also affect the circulation within the shelf, which contribute to cause significant current reversals during the autumn season. Currents at the shelf-estuary connection are clearly supra-inertially forced with the tidal currents playing a key role in the generation of the along-channel velocities. The sub-inertial forcings at this location act mainly to drive the weak ebb currents which were highly correlated with both local and remote wind forcing during the summer season. (C) 2010 Elsevier Ltd. All rights reserved.