Modelação matemática da produção primária em zonas costeiras

O estudo da dinâmica de produção primária apresenta um interesse especial quando realizado em zonas costeiras utilizadas de forma intensiva para a aquicultura, como é o caso da Ria de Arosa. Nesta ria, a cadeia alimentar é dominada pelas elevadas taxas de produção primária sustentadas pelo afloramento de águas oceânicas ricas em nutrientes, resultando em elevadas quantidades de fitoplâncton que, por sua vez, servem de sustento às culturas de mexilhão em bateas. Neste artigo apresenta-se um modelo da cadeia alimentar proposto para a Ria de Arosa. Procede-se à apresentação das principais variáveis de estado seleccionadas e à caracterização das cinéticas que lhes estão associadas, evidenciando-se ainda as principais potencialidades de um modelo deste tipo na avaliação e previsão de cenários de funcionamento da cadeia alimentar

Contribution to the preservation of healthy coastal ecosystems

The release of pollutants into coastal zones from municipal and/or industrial drainage systems is a problem with a considerable environmental impact. In order to minimize the contamination of coastal waters in certain places (e.g., along beaches and in aquacultures), solutions based on the construction of submarine sewer outfalls have been proposed. In order to ascertain the optimal conditions for the release of an emissary, in particular the place of release, it is necessary to characterize the hydrodynamic transport processes that govern the evolution and mixture of pollutants in the area of interest. Circulation in the coastal zone is complicated, given that it is determined by a set of forcing mechanisms of diverse origins (meteorological, astronomical, large-scale ocean circulation, etc.) that endow it with a considerable space-time variation. Wastewater plume behaviour and characteristics depend both on the receiving water conditions and on the discharge characteristics. Accordingly, the implementation of a submarine outfall system requires a prior study of the site where the outfall is to be constructed, in order to achieve optimal rates of dilution of the pollutants released to the environment. Mathematical modelling appears to be a very useful tool for coastal zone environmental management either for continuous monitoring analysis or in accidental ecosystem rupture. This work presents some results and conclusions of two case studies. The first is a study of the pollutant cloud released at the São Jacinto submarine sewer outfall, located about 3 km offshore and 3 km north of an important coastal lagoon (NW Portugal). The main focus of this study was to establish the hydrodynamic conditions in which the pollutant release might affect the coastline (principally the existing beaches and lagoon). The second case presents some hydrodynamic results and water quality aspects of the Ria de Arosa (NW Spain), and also includes an assessment of the environmental impact of wastewater discharges from nine submarine outfalls considered in the sanitation plan of this bay. Results of faecal matter concentration distribution were used in the discussion on the outfall discharges’ impact on the natural water system for different hydrodynamic scenarios. In both cases, 3D numerical models were used

Oil spills in coastal zones : environmental impacts and practical mitigating solutions

A computational structure that has been developed to forecast the time-space evolution of oil spills in marine environments is presented. This structure was developed considering widely used mathematica formulations for oil spreading and weathering processes. A Eulerian transport model, that uses hydrodynamic results obtained with a two-dimensional and a quasi three-dimensional hydrodynamic model, was used to predict the oil slick transport and spread. General characteristics of the computational structure and the results of its application to a real case study - the “Cercal” accident in October 1994 - are presented. Georeferenced data are processed via a Geographical Information System tool. Data on the N/T “Prestige” oil spill processed by means of this information system and simulation results are also included.(undefined

Hydrodynamics and morphodynamics performance assessment of three coastal protection structures

Coastal areas accommodate a great part of large metropolises as they support a great amount of economic and leisure activities. The attraction of people to coastal zones is contributing to an intense and continuous urbanization of these areas, while the ecosystems are threatened by the increase of natural extreme weather events (e.g., intensity and duration of storms, floods), which interfere with local wave climate and changes in morphological beach characteristics. Protection of coastal zones predisposed to coastline recession, due to the action of high tides, high sediment transport deficit, and high wave energy, may involve various coastal structures to reduce or at least to mitigate coastal erosion problems. Many of the current coastal protections (notably groins, seawalls, and emerged breakwaters) were built with a single purpose, which was to protect at all costs without environmental or economic concerns, especially maintenance costs, or the negative consequences that such structures could cause up to considerable distances along the coast. The current concept of integrated coastal zone management presupposes studies involving other types of concerns and more actors in the decision-making process for the implementation of coastal works. In this context, multifunctional structures emerge and are increasingly frequent, such as the so-called multifunctional artificial reefs (MFARs), with the aim of improving leisure, fishing, diving, and other sporting activities, in addition to coastal protection. MFARs are in fact one of the latest concepts for coastal protection. Behind the search for more efficient and sustainable strategies to deal with coastal retreat, this study focused on a comparison between the performance of two traditional coastal protection solutions (submerged detached breakwater and emerged detached breakwater) and an MFAR on a particular coastal stretch. In order to analyse the hydro- (wave height and wave energy dissipation) and morphodynamics (sediment accumulation and erosion areas, and bed level) of the structures and beach interactions, two numerical models were used: SWAN (Simulation WAves Nearshore) for hydrodynamics and XBeach for hydrodynamics and morphodynamics. In addition, a comparison between SWAN and XBeach hydrodynamic results was also performed. From the simulations conducted by SWAN and XBeach, it can be concluded that amongst all structures, the emerged detached breakwater was the most efficient in reducing significant wave heights at a larger scale due to the fact that it constituted a higher obstacle to the incoming waves, and that, regarding both submerged structures (detached breakwater and the MFAR), the MFAR presented a more substantial shadow zone. Regarding morphodynamics, the obtained results presented favourable tendencies to sediment accretion near the shoreline, as well as at the inward areas for the three structures, especially for the emerged detached breakwater and for the MFAR in both wave directions. However, for the west wave direction, along the shoreline, substantial erosion was observed for both structures with more noticeable values for the emerged detached breakwater. For all the northwest wave direction scenarios, no noticeable erosion areas were visible along the shoreline. Overall, considering the balance of erosion and accretion rates, it can be concluded that for both wave predominance, the submerged detached breakwater and the MFAR presented better solutions regarding morphodynamics. The MFAR storm wave condition performed in XBeach indicated substantial erosion areas located around the structure, which added substantial changes in the bed level.This research was funded by the Portuguese Foundation for Science and Technology (FCT), PhD grant number SFRH/BD/141381/201

Slope Processes, Mass Movement and Soil Erosion: A Review

Soil erosion and land degradation are global problems and pose major issues in many countries. Both soil erosion and mass movement are two forms of land degradation and humans play important roles in these geomorphological processes. This paper reviews slope processes associated with mass movement and soil erosion and contributory factors, including physical and human agents. Acting together, these cause diverse geomorphological features. Slope processes are illustrated by reference to case studies from Brazil and UK. The causes and impacts of erosion are discussed, along with appropriate remedial bioengineering methods and the potential of the measures to prevent these types of environmental degradation. Although there are several agents of erosion, water is the most important one. Cultivation can promote soil erosion, due to ploughing and harvesting, which moves soil down slopes. Soil erosion and mass movement data would inform the viability of soil conservation practices. Integrated management of drainage basins offers a promising way forward for effective soil conservation and soil remedial bioengineering in Brazil and UK

Fricción y tensión tangencial por fondo con ola y corriente

[ES] Se calcula la tensión tangencial debido a ola y corriente mediante un modelo numérico con cierre turbulento K-L, donde K es la energía cinética turbulenta y L es la escala longitudinal de turbulencia. Se obtiene el coeficiente de fricción parametrizado para el caso de flujo turbulento rugoso, siguiendo a Soulsby et al. (1994) y se amplía al caso de flujo turbulento liso. La comparación de estos resultados con otros existentes en la literatura, especialmente los proporcionados por Tanaka y Thu (1994) muestra un buen ajuste.Se propone una nueva parametrización de la serie temporal de la tensión tangencial que incluye el coeficiente de fricción local obteniéndose mejores resultados que aplicando la parametrización propuesta por Soulsby et al. (1994).Este trabajo se ha llevado a cabo en el ámbito del Proyecto “Modelación de Régimen Turbulento en Zonas Costeras-Aplicaciones a la Dinámica de Sedimentos y Dispersión de Contaminantes”, financiado por la Fundação para a Ciencia e a Tecnología (FCT), bajo el contrato de investigación PBIC/C/MAR/2247/95. Asimismo, se reconoce la contribución de los projectos “SEDMOC-Modelación del Transporte de Sedimentos en Entornos Marinos Costeros” y “Parametrización del Coeficiente de Fricción en Régimen Variable: Aplicaciones al Golpe de Ariete y Transporte de Sedimentos”, financiados por la UE con el contrato nº MAS3-CT97-0115 y por la FCT con el contrato nº PRAXIS//3.1/CEG/2503/95, respectivamente.Antunes Do Carmo, JS.; Temperville, A.; Seabra Santos, F. (2003). Fricción y tensión tangencial por fondo con ola y corriente. Ingeniería del agua. 10(2):177-188. https://doi.org/10.4995/ia.2003.2583OJS177188102Antunes do Carmo J.S., F.J. Seabra-Santos and E. Barthlemy, 1993. Surface waves propagation in shallow-water: a finite element model. Int. J. Num. Meth. in Fluids, Vol. 16, No. 6, 447-459.Arnskov M.M, J. Fredsøe and B.M. Sumer, 1993. Bedshear stress measurements over a smooth bed in three-dimensional wave-current motion. Coastal Engineering, 20,277-316.Fredsøe J., 1984. Turbulent boundary layer in wave-current-motion. J. Hydraul. Eng., 110 (8), 1103-1120.Huynh Thanh S., 1990. Modélisation de la couche limite turbulente oscillatoire générée par l'interaction houle courant en zone côtière. Thèse à l'Institut National Polytechnique de Grenoble.Huynh Thanh S. and A. Temperville, 1991. A numerical model of the rough turbulent boundary layer in combined wave and current interaction. In: R.L. Soulsby and R. Betess (Editors), Sand Transport in Rivers, Estuaries and the Sea. Balkema, Rotterdam, pp. 93-100.Jensen B.L., B.M. Sumer and J. Fredsøe, 1989. Turbulent oscillatory boundary layers at high Reynolds numbers. Journal of Fluid Mechanics, 206, 265-297.Jonsson I.G., 1966.Wave boundary layers and friction factors. Proc. 10th Int. Conf. Coastal Eng., Tokyo, 127-148.Jonsson I.G. and N.A. Carlsen, 1976. Experimental and theoretical investigations in an oscillaory turbulent boundary layer. Journal of Hydraulics Research, 14(1), 45-60.Kamphuis J.W., 1975. Friction factor under oscillatory waves. J. Waterw. Port Coastal Ocean Eng., 101 (WW2), 135-144.Ockendenand M.C., R.L.Soulsby, 1994. Sediment transport by currents plus irregular waves. Report SR 376, HR Wallingfort, HR Wallingfort Ltd. Howbery Park, Wallingfort, Oxfordshire, OX10 8BA, UK.Sleath J.F.A., 1987. Turbulent oscillatory flow over rough beds. Journal of Fluid Mechanics, 182, 369-409.Sleath J.F.A., 1991. Velocities and shear stresses in wavecurrent flows. Journal of Geophysical Research, Vol. 96, No. C8, 15, 237-15, 244.Soulsbyand R.L., M.C.Ockenden, 1994. Sediment transport by currents plus irregular waves. Report SR 237, HR Wallingfort.Soulsby R.L., L. Hamm, G. Klopman, D. Myrhaug,Simons R.R and G.P. Thomas, 1994. Wave-current interaction within and outside the bottom boundary layer. Coastal Eng., 21, 41-69.Sumer B.M., B.L. Jensen and L. Fredsøe, 1987. Turbulence in oscillatory boundary layers. In Advances in Turbulence. Springer, Heidelberg, 556-567.Swart D.H., 1974. Offshore sediment transport and equilibrium beach profiles. Delft Hydraulics Lab., Publ. 131.Tanaka H. and N. Shuto, 1981. Friction coefficient for a wave-current coexistent system. Coastal Eng. Japan, 24, 105-128.Tanaka H. and N. Shuto, 1984. Friction laws and flow regimes underwave and current motion. Journal of Hydraulic Research, 22(4), 245-261.Tanaka H. and A. Thu, 1994. Full-range equation of friction coefficient and phase difference in a wave-current boundary layer. Coastal Eng., 22, 237-254.Tran Thu T. and A. Temperville, 1994. Numerical model of sediment transport in thewave-current interaction. Proc. of the Advanced Seminar on Modelling of Coastal and Estuarine Processes. Coimbra, Portugal, 271-282.Tran Thu T., 1995. Modélisation numérique de l'interaction houle-courant-sédiment. Thèse à l'Université Joseph Fourier-Grenoble I

Concentrações de microminerais (cobre, cobalto, ferro, molibdênio e zinco) no fígado de vacas leiteiras da Região de Campos Gerais, Paraná, Brasil

Universidade Federal do Paraná. Departamento de Medicina Veterinária. Curitiba, PR, Brazil.Universidade Federal do Pará - Campus Castanhal. Instituto de Medicina Veterinária. Castanhal, PA, Brazil.Universidade Federal do Pará - Campus Castanhal. Instituto de Medicina Veterinária. Castanhal, PA, Brazil.Universidade Federal do Sul e Sudeste do Pará. Instituto de Estudos do Trópico Úmido. Xinguara, PA, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde e Ambiente. Instituto Evandro Chagas. Laboratório de Toxicologia. Ananindeua, PA, Brasil.Universidade Federal do Paraná. Departamento de Medicina Veterinária. Curitiba, PR, Brazil.Universidade do Estado de Santa Catarina. Departamento de Medicina Veterinária. Florianópolis, SC, Brazil.Universidade Federal do Paraná. Departamento de Medicina Veterinária. Curitiba, PR, Brazil.Universidade Federal do Paraná. Departamento de Medicina Veterinária. Curitiba, PR, Brazil.This study collected samples from 50 Holstein cows, most intensively bred, and from the Campos Gerais region, Paraná, with an average milk production of 30.21L/day. Samples of the liver, spleen and lymph nodes were collected to determine the levels of copper, cobalt, iron, molybdenum and zinc. Spleen and lymph nodes were subjected to histological analysis and evaluation of the degree of hemosiderosis. The average concentrations of copper (495.05ppm), molybdenum (4.19ppm), and zinc (274.49ppm) were higher than those established for the bovines. For cobalt 26% of the animals presented levels below the established level, which characterized cobalt deficiency. Only iron (299.12ppm) exhibited an adequate average level. Histopathologically hemosiderosis was observed mainly in the spleen (78%) and less frequently in the lymph nodes (20%). The observation of hemosiderin in the spleen and lymph nodes is not related to copper deficiency. Still it may be related to high levels of molybdenum, zinc, iron, or other undetermined causes

Modified Brans-Dicke theory of gravity from five-dimensional vacuum

We investigate, in the context of five-dimensional (5D) Brans-Dicke theory of gravity, the idea that macroscopic matter configurations can be generated from pure vacuum in five dimensions, an approach first proposed in the framework of general relativity. We show that the 5D Brans-Dicke vacuum equations when reduced to four dimensions lead to a modified version of Brans-Dicke theory in four dimensions (4D). As an application of the formalism, we obtain two five-dimensional extensions of four-dimensional O'Hanlon and Tupper vacuum solution and show that they lead two different cosmological scenarios in 4D.Comment: 9 page