We investigated the occurrence and seasonal variation of the biomass of rotifers, tintinnids, the heterotrophic dinoflagellate Gyrodinium fusus and copepod nauplii in the Bahía Blanca Estuary ...(38°42′S61°50 ′W), Argentina, during an annual cycle. The rotifers fauna comprised three species, while the tintinnids were represented by sixteen species. The biomass of the rotifers fluctuated between 0.62 and 8.90 µgC l−1. The biomass of the tintinnids fluctuated between 0.13 and 9.37 µgC l−1, the biomass of the nauplii stages between 1.78 and 7.65 µgC l−1; while the biomass of G. fusus varied from 0.26 and 7.94 µgC l−1, these results are compared to estimates of microzooplankton in other regions. We analysed the presence of the different groups in relation to the environmental variables, based on point-biserial correlation. Salinity fluctuated between 25.14 and 36.64; temperature between 7.5 and 23.2°C, solar radiation between 0.9 and 30.8 MJ m−2d−1 and Secchi distance between 0.25 and 1.43 m. Rotifers were correlated positively with temperature, chlorophyll-a and Secchi depth and negatively with salinity. The tintinnids were positively correlated with salinity. Gyrodinium fusus was positively correlated with Secchi depth, and chlorophyll-a, and negatively with temperature and solar radiation. Nauplii stages were negatively correlated with chlorophyll-a. Based on the occurrence of the microzooplankters in relation to the physico-chemical variables, it was possible to establish two seasonal assemblages: (a) the co-occurrence of the rotifers and the heterotrophic dinoflagellate G. fusus during the winter–spring; and (b) the tintinnids and nauplii larvae during the summer. We conclude that, in this estuary, physico-chemical variables are the forcing factors that directly, or indirectly, influence the seasonal assemblages of the microzooplankton.
Suitable response of hydraulic structures to seismic actions represents an important requirement in order to organise aid in the areas damaged by seismic events; therefore accurate assessment of ...hydrodynamic loads acting on the structure represents the first step in a correct anti-seismic structural design. With particular reference to water storage tanks, the problem of hydrodynamic actions exerted by an earthquake on the walls of a tank has been investigated, whether fully or partially buried below ground and considered to be non-deformable (‘rigid’ scheme), and the tank’s tendency to deform has been analysed, taking into account the liquid-shell interaction (‘elastic’ scheme) and highlighting its sometimes significant influence on the entity of hydrodynamic actions. The aim of this research project is to analyse elevated storage tanks in seismic areas, comprising a tank mounted on a single vertical column. Applying the same considerations made for ‘ground-based’ tanks to such a scheme is immediately possible because the liquid mass fully enters the energy balance of the structural system and its quantity does not vary over time and formal variations in the hydraulic profile over time do not entail substantial modifications in the system’s overall response. Analysis of the dynamic response of elevated tanks, performed by means of the mathematical model described and limited to concrete structural systems with a circular tank, has shown that the entity of hydrodynamic motions can be significant and, furthermore, noticeably greater than those for equally sized tanks on the ground.
Unlike rivers, tidal-paths present different drainage configurations within their complex distribution. The determinations of their features is the first step towards modeling their evolution. In ...this work, a methodology is presented for automatic morphometric extraction and characterization of tidal-paths over high resolution satellite images (IKONOS, 1 m resolution). The algorithm accurately computes the total length of the structure. In addition, it identifies and characterizes each branch by super-resolution. Then, the drainage paths without loops are classified defining the order in which they flood and ebb by effect of the tides. The method was tested on two tidal-paths with very different features: a rectangular or trellis drainage, and a dendritic one.
The purpose of this work is to identify and quantify those stretches in the Buenos Aires province that present different degrees of risk in view of the rise of the mean sea level and to determine its ...nature. The study focused on the Buenos Aires province coast because its variant geomorphology represents the different morphologies along the whole of the Argentinean coastline. The aim of this article is to study the response of two of the coastal vulnerability equations to the environmental diversity and to determine which one is more suitable to be applied to the rest of the country. On verifying the equations, CVI6 was found to be more appropriate for the analysis of coasts with different morphologies. Depending on the physical characteristics of each area, the consequences would include flooding and the loss of low lands in areas such as the Samborombón Bay, Bahía Blanca Estuary, and Anegada Bay, and the eroding of the beaches between Punta Rasa and Bahía Blanca.
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Multiple regressions, wavelet spectra, and Fourier spectra were employed to analyze fluctuations in the surface areas of 2 Patagonian lakes during 1998-2015 and relate these to fluctuations in ...precipitation, evaporation, river discharge, and 2 southern climate modes, the Antarctic Oscillation (AAO) and El Niño Southern Oscillation, expressed in terms of the Southern Oscillation Index (SOI). Multiple regression analysis suggested that discharge was the primary driver of interannual lake area variations. Cross-spectrum analysis demonstrated a maximum significant correlation between river discharge and both AAO and SOI indices at annual and interannual timescales (2-3 yr). During 1998-2015, the annual discharge signal was related to both the AAO annual and every 2 year signals. When a strong La Niña (positive SOI) event occurred, however, river discharge was significantly reduced, resulting in a decrease in lake surface area.
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The study area comprises a sector of the main channel of the entrance to Bahı́a Blanca system harbour. El Toro channel, characterized by recurrent accumulation processes, had to be dredged ...periodically to maintain the nominal depth of 10m. Detailed surveys of the reach are made regularly to check the navigation conditions. A set of survey charts made within two dredging operations and covering about 1 year was analysed by means of principal component analysis (PCA). The first principal component obtained from PCA describes the mean depth of the area, while the second principal component explains the morphological variations over time. From it, the accumulation periodicity can be detected, and, therefore, when dredging becomes necessary. Based on dynamics studies, a large transverse flood current component is observed which is attributed to a postulated helicoidal flow pattern responsible for the large sediment accumulation observed in the south-east of the El Toro channel.
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Dealing with issues related to the modelling, monitoring and management of air pollution, this book includes papers presented at the Air Pollution 2018 international conference. The papers from this ...conference continue a wide ranging collection of high quality research works that develop the fundamental science of air pollution.
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