Geo(anthropo)genic factors affecting the radioactivity in groundwaters from Guarani aquifer, Brazil

This investigation was carried out within the Paraná sedimentary basin, involved the sampling of 77 pumped tubular wells, and was realized with the puipose of evaluating the radioactivity in the Brazilian part of Guarani (Botucatu-Pirambóia, Tacuarembó, Misiones) aquifer. The radioactivity due to nuclides belonging to uranium and thorium series decay was investigated in terms of the uranium isotopes 234U and 238U, radon (222Rn), and the radium isotopes 226Ra and 228Ra. The obtained results were compared with the maximum permissible concentration limits in drinking water defined by the Brazilian national standard, as well with the guidelines for drinking water quality established by the World Health Organization. The importance of water-rock/soil interactions was considered in order to explain most of the obtained data.

The reproductive biology of Diplodus argenteus (Sparidae) in the coastal upwelling system of Cabo Frio, Rio de Janeiro, Brazil

The reproductive biology of the seabream Diplodus argenteus, a dominant coastal fishery species, was investigated over two consecutive seasons (2001-2002) at Cabo Frio, Brazil, a low-latitude upwelling system. The sex ratio was dominated by females (1.4:1.0) and the length-at-50% sexual maturity (females) was 203mm total length. Females were multiple spawners and the reproductive pattern appeared to be digynous protandrous hermaphroditism. Monthly variations in gonadosomatic index and proportion of ripe females indicated that reproductive activity occurred from late winter to summer (August-February), following coastal upwelling. Copyright © NISC Pty Ltd.

Vertical migration during tidal transport of megalopae of Necora puber in coastal shallow waters during daytime

For meroplanktonic larvae that must settle in coastal areas, their successful return to the shore is determined largely by physical transport processes; however, many organisms perform vertical movements to aid successful recruitment. In this study, daytime tidal vertical migration of megalopae of the velvet swimming crab Necora puber was investigated across two different exposures in the shallow waters of Plymouth Sound. Crabs were collected using a plankton net at the surface and near the bottom during flood and ebb tides. Distribution of the pelagic postlarvae was patchy and the abundance varied spatially in tens and thousands of metres. In temporal scales, the annual pattern was dominated by low occurrence of megalopae, punctuated by episodic peaks of high abundance. Most megalopae were collected at the surface irrespective of the tidal phase. The effect of wave exposure on the vertical migration of megalopae was not clear, although there was a general higher abundance of megalopae on exposed shores. Daytime abundance in the water column appears to be regulated by the tidal cycle, as megalopae were more abundant during flood than ebb tides. Although the megalopae do not appear to make large vertical migrations, this behaviour should produce a net shoreward transport. © 2005 Elsevier Ltd. All rights reserved.

Select bibliography on coastal area development and environmental, physical and regional planning in the Caribbean region

Bibliografía sobre desarrollo de las áreas costeras, planificación del medio ambiente, recursos marinos, planificación regional y física, y puertos del Caribe.

Interaction between wave and coastal structure: Validation of two lagrangian numerical models with experimental results marine 2011

Numerical modeling of the interaction among waves and coastal structures is a challenge due to the many nonlinear phenomena involved, such as, wave propagation, wave transformation with water depth, interaction among incident and reflected waves, run-up / run-down and wave overtopping. Numerical models based on Lagrangian formulation, like SPH (Smoothed Particle Hydrodynamics), allow simulating complex free surface flows. The validation of these numerical models is essential, but comparing numerical results with experimental data is not an easy task. In the present paper, two SPH numerical models, SPHysics LNEC and SPH UNESP, are validated comparing the numerical results of waves interacting with a vertical breakwater, with data obtained in physical model tests made in one of the LNEC's flume. To achieve this validation, the experimental set-up is determined to be compatible with the Characteristics of the numerical models. Therefore, the flume dimensions are exactly the same for numerical and physical model and incident wave characteristics are identical, which allows determining the accuracy of the numerical models, particularly regarding two complex phenomena: wave-breaking and impact loads on the breakwater. It is shown that partial renormalization, i.e. renormalization applied only for particles near the structure, seems to be a promising compromise and an original method that allows simultaneously propagating waves, without diffusion, and modeling accurately the pressure field near the structure.

A comparative study of aquifer systems occurring at the Paraná sedimentary basin, Brazil: U-isotopes contribution

The radioactivity due to 238U and 234U in three aquifer systems occurring within the Paraná sedimentary basin, South America, has been investigated. Uranium is much less dissolved from fractured igneous rocks than from the porous sedimentary rocks as indicated by the U-mobility coefficients between 7. 6 × 10-6 and 1. 2 × 10-3 g cm-3. These values are also compatible with the U preference ratios relative to Na, K, Ca, Mg and SiO2, which showed that U is never preferentially mobilized in the liquid phase during the flow occurring in cracks, fissures, fractures and faults of the igneous basaltic rocks. Experimental dissolution of diabase grains on a time-scale laboratory has demonstrated that the U dissolution appeared to be a two-stage process characterized by linear and second-order kinetics. The U dissolution rate was 8 × 10-16 mol m-2 s-1 that is within the range of 4 × 10-16-3 × 10-14 mol m-2 s-1 estimated for other rock types. The 234U/238U activity ratio of dissolved U in solutions was higher than unity, a typical result expected during the water-rock interactions when preferential 234U-leach from the rock surfaces takes place. Some U-isotopes data allowed estimating 320 ka for the groundwater residence time in a sector of a transect in São Paulo State. A modeling has been also realized considering all U-isotopes data obtained in Bauru (35 samples), Serra Geral (16 samples) and Guarani (29 samples) aquifers. The results indicated that the Bauru aquifer waters may result from the admixture of waters from Guarani (1. 5 %) and Serra Geral (98. 5 %) aquifers. © 2012 Springer-Verlag.

Checklist of freshwater ichthyofauna from coastal streams of Juréia-Itatins Reserve, Southeastern Brazil

The Juréia-Itatins Ecological Station (JIES) is one of the few protected areas in the state of São Paulo, which harbor a significant portion of the Atlantic forest. Although there is high diversity and endemism of fish species in this region, knowledge of the ichthyofauna in JIES is incipient. A total of 4,809 specimens belonging to six orders, 15 families and 31 species were captured during April 2009 to February 2010, using electrofishing, gillnets and traps. The family Characidae was predominant, mainly due to the abundance of freshwater species such as Astyanax ribeirae, Mimagoniates microlepis, and Hollandichthys multifasciatus. Although the estuarine regions were rarely sampled in this study, six brackish water species were captured. In this study, nine species previously unknown from JIES were discovered. Five endangered fish species, endemic to the Atlantic forest, occur at JIES, thus the presence of protected areas, as a conservation measure, is particularly relevant. © 2013 Check List and Authors.

High-resolution aquifer analog of fluvial-aeolian sediments of the Guarani aquifer system

The Guarani aquifer system (GAS) represents one of the biggest aquifers in the world and is the most relevant groundwater resource in South America. For the first time, by combining field and laboratory measurements, a high-resolution aquifer analog model of fluvial-aeolian sediments of the GAS in São Paulo State (Brazil) is constructed. Three parallel sections of frontal outcrops, 28 m × 5.8 m, and two parallel sections of lateral outcrops, 7 m × 5.8 m, are recorded during open-pit mining of sandy sediments and describe in detail the three-dimensional distribution of the local lithofacies and hydrofacies. Variations of hydraulic conductivity, K, and porosity, n, are resolved on the centimeter scale, and the most permeable units of the fluvial-aeolian facies association are identified. The constructed aquifer analog model shows moderate hydraulic heterogeneity and a mean K value of 1.36 × 10-4 m/s, which is greater than the reported range of K values for the entire GAS in São Paulo State. The results suggest that the examined sedimentary unit constitutes a relevant portion of the GAS in São Paulo State in the context of groundwater extraction and pollution. Moreover, the constructed aquifer analog is considered an ideal basis for future numerical model experiments, aiming at in-depth understanding of the groundwater flow and contaminant transport patterns at this GAS portion or at comparable fluvial-aeolian facies associations. © 2013 Springer-Verlag Berlin Heidelberg.

Desarrollo de la zona costera: desarrollo y medio ambiente del Caribe en los aspectos costero y marítimo: programas y actividades posibles = Coastal area development: development and environment in the Caribbean coastal and marine aspects: possible programmes and activities

Incluye Bibliografía

Informe de la Reunión del Grupo de Expertos en Planificación de los Usos del Mar y Administración de las Zonas Costeras en América Latina y el Caribe = Report of the Expert Group Meeting on Sea Use Planning and Coastal Area Management in Latin America and the Caribbean

Contiene la asistencia, organización de los trabajos y resumen de los debates de la reunión que tuvo por objetivo examinar las experiencias nacionales en la planificación y administración de las zonas costeras y oceánicas, la cooperación entre los países de la región, el papel de las Naciones Unidas y de las organizaciones regionales, y la identificación de las principales necesidades de los Estados de la región.

La protección y el manejo de océanos, mares y zonas costeras en la Plataforma de Tlatelolco sobre Medio Ambiente y Desarrollo: un análisis práctico de sus alcances = The protection and management of oceans, seas and coastal areas under the Tlatelolco Platform on Environment and Development: a practical analysis of its implications

Incluye Bibliografía