The Patos Lagoon hydrodynamics during an El Niño event (1998)

Fernandes, Elisa Helena Leão; Dyer, K.R.; Möller, Osmar Olinto; Niencheski, Luís Felipe Hax

doi:10.1016/s0278-4343(02)00033-x

Cited by 132 publications

(93 citation statements)

References 20 publications

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“…In the central lagoon, the major effect of the river inflow is to establish a positive cross-shore pressure gradient, in agreement with the two-dimensional results of Fernandes et al (2002). Oscillatory motions generated after wind relaxation are attenuated by the river inflow, and are not sufficient to cause the flow to revert.…”

Section: Discussionsupporting

confidence: 85%

“…The positive cross-shore pressure gradient occurs everywhere along transects A and B for high discharges (not shown), even in the deeper parts, in contrast to the basic case experiment. This lateral set up/set down is consistent with the results of Fernandes et al (2002). As the wind decreases in intensity during the relaxation event, the alongshore pressure gradient in the lagoon is reversed (Fig.…”

Section: Dynamics In the Lagoon's Entrance Channelsupporting

confidence: 89%

“…River discharge can also be important in the exchange. In extreme conditions of high-discharge, volumes of water equivalent to up to 7% of the lagoon volume can be flushed out in time intervals as short as 6 h (Fernandes et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

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A modeling study of Patos lagoon (Brazil) flow response to idealized wind and river discharge: dynamical analysis

Castelao

Möller

2006

Braz. j. oceanogr.

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A B S T R A C TA three-dimensional numerical model is used to investigate the Patos Lagoon flow response to idealized northeasterly winds and river inflow. North of Ponta da Feitoria, in the central lagoon, the main balance in the alongshore direction at steady state is between the surface stress and the pressure gradient, with a small contribution from the bottom stress. The alongshore variability in the pressure gradient is balanced by the Coriolis acceleration. In the cross-shore direction, the balance is nearly geostrophic, with deviations from that balance in the shallow regions, where the bottom stress term makes a significant contribution. Close to headlands, nonlinear terms are also important, leading to an additional increase in the cross-shore pressure gradient. Relaxation events were found to be important for seiche generation in the central lagoon. Close to the lagoon's mouth, nonlinear terms were found to be the major terms balancing the pressure gradient generated in response to the wind forcing. After the wind relaxation, the pressure gradient in the estuarine region is reversed, driving a landward flow. River inflow acts to dampen out the generation of seiches following wind relaxations. A river inflow Q = 2000 m 3 s -1 was found to be sufficient to shut down the landward flow generated following relaxation events. R E S U M OUm modelo numérico tridimensional é utilizado para investigar a circulação na Lagoa dos Patos em resposta aos ventos e à descarga fluvial. Ao norte da Ponta da Feitoria, o principal balanço na direção longitudinal é entre o estresse superficial e o gradiente de pressão, com pequena contribuição do estresse de fundo. A variabilidade longitudinal no gradiente de pressão é balanceada pela aceleração de Coriolis. Na direção transversal à lagoa, o balanço é aproximadamente geostrófico, com desvios deste balanço nas regiões rasas, onde o estresse de fundo contribui significamente. Os termos não lineares são importantes próximo aos cabos, causando um aumento adicional no gradiente de pressão na direção transversal. Eventos de relaxação são significativos na geração de seiches na parte central da lagoa. Próximo à desembocadura da lagoa, os termos não lineares são os principais termos contrapondo-se ao gradiente de pressão gerado pela ação dos ventos. O gradiente de pressão é revertido após a relaxação dos ventos, causando a entrada de água na lagoa. A descarga fluvial atenua a geração de seiches após a relaxação. Valores médios de descarga (Q = 2000 m 3 s -1 ) são suficientes para impedir a entrada de água na lagoa após a relaxação do vento.

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Section: Discussionsupporting

confidence: 85%

Section: Dynamics In the Lagoon's Entrance Channelsupporting

confidence: 89%

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A modeling study of Patos lagoon (Brazil) flow response to idealized wind and river discharge: dynamical analysis

Castelao

Möller

2006

Braz. j. oceanogr.

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“…It is considered the largest choked coastal lagoon in the world 20 and similar to most choked coastal lagoon systems, the Patos Lagoon is wind forced rather than tidal driven. 21 The predominant NE-SW wind regime is the principal forcing factor and it decisively controls circulation, salinity distribution and water levels. 22 The only contact of the lagoon with the sea is through a relatively small inlet at its southern end, near the city of Rio Grande ( Figure 1).…”

Section: Study Sitesmentioning

confidence: 99%

In situ measurement of trace metals in estuarine waters of Patos Lagoon using diffusive gradients in thin films (DGT)

Wallner-Kersanach

Andrade

Zhang

et al. 2009

J. Braz. Chem. Soc.

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A técnica de gradiente difusivo de membrana (DGT) foi utilizada para determinar metais lábeis in situ durante diferentes condições hidrológicas no estuário da Lagoa dos Patos. As amostras de água foram também analisadas para a fração lábil-Chelex para Cd, Co, Cu, Mn, Ni e Zn usando resina Chelex-100. As concentrações lábeis-DGT de Cd, Cu, Ni e Zn foram mais baixas que a lábil-Chelex, possivelmente devido à ligação do metal coloidal na coluna de resina Chelex. Os resultados do DGT indicaram um decréscimo nas concentrações de todos os elementos, refletindo trocas na especiação dos metais em solução causada pela diminuição da salinidade e associado a mudanças de pH no estuário. Os resultados demonstraram a sensibilidade do DGT para a especiação dos metais e a capacidade do uso da técnica DGT em águas estuarinas altamente dinâmicas para a obtenção de concentrações de metais lábeis integradas ao longo do tempo.The diffusive gradients in thin-films (DGT) technique was used to determine labile metals in situ during different hydrological conditions in the Patos Lagoon estuary. Water samples were also analyzed for Chelex-labile fractions of Cd, Co, Cu, Mn, Ni and Zn using Chelex-100 resin. DGT-labile concentrations of Cd, Cu, Ni and Zn were lower than Chelex-labile concentrations, possibly because colloids were trapped in the Chelex resin column. There was a decrease with increasing deployment time in the concentrations of all elements measured by DGT, reflecting changes in metal speciation in solution caused by the decrease in the salinity and associated with change in pH in the estuary. The results demonstrated the sensitivity of DGT to metal speciation and the feasibility of using the DGT technique in highly dynamic estuarine waters to obtain a time-integrated record of labile trace metals. Keywords: DGT, labile metal, estuary IntroductionTrace metals are one of the major contaminants of estuarine and coastal areas, as a result of coastal development and, consequently, inputs from many anthropogenic sources. 1 Elements such as Cu, Ni, Mn and Zn play an important role as essential elements in aquatic systems. However, elevated concentrations of these elements, and of nonessential elements such as Cd, may cause toxicity for aquatic organisms. The investigation of metal bioavailability in water is as important as metal concentration when considering the impact of metals on an environment.The free metal ion (M 2+ ) and labile metal species in solution are the forms of dissolved metal often accumulated by aquatic organisms. 2 Uptake may occur directly into phytoplankton cells 3 or across gill membranes in fish. 4 So, speciation studies of trace metals have become important, as it enables evaluation of trace metal bioavailability and mobility. Available techniques include anodic stripping voltammetry, 5 cathodic stripping voltammetry 6 and ionexchange columns. 7 However, with standard equipment, all these methods require analyses to be done on a sample brought to the laboratory and metal speciation may change in this time ...

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“…Eventos episódicos de drenagem e intensidade dos ventos na escala intra-anual (North & Houde 2001), precipitação, pressão atmosférica, o regime, a intensidade e a direção dos ventos são fatores ambientais importantes para a dinâmica estuarina (Costa et al 1988, Garcia 1998, Fernandes et al 2001. Desta forma, estes fatores podem regular o período de desova e/ou influenciar a dispersão de larvas (North & Houde 2001).…”

Section: Introductionunclassified

Distribuição espacial e variações temporais da abundância de ovos e larvas de Micropogonias furnieri no estuário da Lagoa dos Patos: registros históricos e forçantes ambientais

Bruno¹,

Muelbert²

2009

Atlântica

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-96201-900 -Rio Grande -RSBrasil. 2 docbruno@furg.br RESUMO As espécies de peixes que ocorrem no estuário da Lagoa dos Patos (ELP) apresentam diferentes estratégias de desova que procuram otimizar um balanço entre condições ambientais locais e remotas, e seu ciclo de vida. O presente trabalho descreve e analisa a distribuição espacial, variabilidade temporal e a influência de variáveis ambientais sobre a abundância de ovos e larvas de Micropogonias furnieri no ELP. Foram utilizadas variáveis ambientais e um banco de dados de ictioplâncton com registros históricos. O ictioplâncton foi coletado com rede de plâncton com malha de 300 ou 500 µm em amostras mensais e/ou quinzenais. Análise de variância foi utilizada para testar os efeitos da variação temporal e distribuição espacial sobre a abundância média de ovos e larvas. Salinidade, temperatura, pressão atmosférica e velocidade dos ventos foram importantes na variabilidade sazonal da abundância, enquanto a precipitação e vazão foram importantes para as diferenças interanuais. A abundância de ovos e larvas foi maior no estuário inferior e durante a primavera e verão. Estes resultados sugerem que a variabilidade na distribuição dos primeiros estágios de vida de M. furnieri é determinada por diferentes escalas temporais. ABSTRACTFish species from the Patos Lagoon Estuary (PLE) adopt different spawning strategies to optimize the balance between remote and local environmental conditions during their life cycle. The purpose of this study was to describe and analyze the spatial distribution, temporal variability and the influence of environmental variables on the abundance of eggs and larvae of Micropogonias furnieri in the PLE. Environmental variables and ichthyoplankton historical records were used in the analysis. Ichthyoplankton was collected with a 300 or 500 µm-plankton net in monthly and/or fortnightly samples. Analysis of variance was used to test the effects of spatial distribution and temporal variation on the average abundance of eggs and larvae. Temperature, salinity, atmospheric pressure and winds were important for the seasonal variability of abundance, while precipitation and water discharge were important for interannual differences. The abundance of eggs and larvae in the estuary was higher in the lower estuary during spring and summer. These results suggest that the variability in the distribution of early life stages of M. furnieri is determined at different time scales.

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The Patos Lagoon hydrodynamics during an El Niño event (1998)

Cited by 132 publications

References 20 publications

A modeling study of Patos lagoon (Brazil) flow response to idealized wind and river discharge: dynamical analysis

A modeling study of Patos lagoon (Brazil) flow response to idealized wind and river discharge: dynamical analysis

In situ measurement of trace metals in estuarine waters of Patos Lagoon using diffusive gradients in thin films (DGT)

Distribuição espacial e variações temporais da abundância de ovos e larvas de Micropogonias furnieri no estuário da Lagoa dos Patos: registros históricos e forçantes ambientais

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