Chemical Reduction of Hexavalent Chromium Present in Contaminated Soil using a Packed-bed Column Reactor

Soil samples extracted from a contaminated landfill with hexavalent chromium, Cr(VI), were treated in a packed-bed column reactor applying different reductant solutions under controlled flow conditions. In all cases, the kinetic study concerning removal of Cr(VI) from packed soil revealed the overall process (leaching and redox reaction) is described by pseudo-first order kinetics. The complexity of the process taking place in non-isotropic medium (packed soil) was evidenced by dependence of the overall pseudo-first order kinetic rate constant, k*, on treatment time, volumetric flow rate, and composition and concentration of the reductant solution. A phenomenological equation was proposed in order to represent k* in non-ideal conditions. The comparative study concerning the use of different reductants revealed application of ferrous sulphate, Fe(II), under flow conditions furnished the best results, since in this case the redox process reached a considerable extent and the reduced chromium, Cr(III), was immobilized in packed soil as an insoluble mixed compound.     

HDR devices for the seismic protection of frame structures: Experimental results and numerical simulations

As part of a national research programme an experimental campaign was carried out on a real scale mock‐up consisting of a steel–concrete composite frame equipped with dissipative bracings, based on high damping rubber (HDR) devices. Free vibration tests, followed by force‐controlled and displacement‐controlled cyclic tests were performed. The experimental tests were aimed at studying the dynamic response of the coupled system in order to demonstrate the effectiveness of HDR devices in increasing the stiffness and dissipation capacity of the frame and investigating the ability of the constitutive HDR model proposed by the authors to predict the dynamic response of the coupled system. Copyright © 2009 John Wiley & Sons, Ltd.     

Flow-induced vegetation uprooting in a meandering bend:Experimental investigation

Vegetation uprooting is a complex process which depends on many interrelated factors. In this paper,attention is focused on the flow-induced uprooting in river bends, where the flow characteristics vary as effected by the channel’s curvature and its continuous changing in the downstream direction. Results are presented by an experimental work done in a high-amplitude meandering flume with mature herbaceous vegetation on the bed. In the first part of the paper, the variation along the bend of the...     

Influence of environmental variability on distribution and relative abundance of baleen whales (suborder Mysticeti) in the Gulf of California

The Gulf of California (GC) is one of the most productive seas in the Pacific Ocean because of several oceanographic phenomena that support many marine mammal species, particularly of the cetacean order. The environmental variability of the GC was analysed during the cold and warm periods of 2005 and 2006 and its effects on the distribution and relative abundance of baleen whales using sea surface temperature (SST) and chlorophyll a (Chl a) concentration. Satellite image analysis allowed us to detect important differences in both Chl a concentration and SST including cold to warm periods, even between the two cold periods and between the two warm periods. The cold periods had the highest number of whales: 99 individuals in 2005 and 183 in 2006, which were distributed along the entire gulf. Fewer animals were recorded in the warm period: 46 individuals in 2005 and 30 in 2006, which were mainly distributed in the northern part of the gulf. We concluded that SST influenced the relative abundance of baleen whales while Chl a concentration influenced their distribution.     

Tourism impacts on benthic communities of sandy beaches

This study evaluated the effect of human trampling on the benthic macrofauna of two beaches in Southeast Brazil with different levels of intensity of tourism, Grussaí (more impacted) and Manguinhos (less impacted), during periods of high and low tourism activity. The macrofauna of urbanized (U) and non‐urbanized (NU) sectors of the inter‐tidal zone was sampled and the number of visitors was recorded. General linear models revealed a decreasing in abundance of macrofauna species in the urbanized sectors of analyzed beaches, which are exposed to higher trampling impact than in non‐urbanized areas. At Manguinhos Beach, trampling did not affect the macrofauna (<1 visitors ? m^?²), except for the polychaete Scolelepis sp., which was less abundant in the U sector. Considering the benthic community, Atlantorchestoidea brasiliensis, Hemipodia californiensis and Scolelepis sp. were more sensitive to human trampling pressure and may be used as potential bioindicators of tourism impact. Management plans should consider mitigation of the effects of tourism, such as the control of the visitor number and their decentralization.     

Geostatistical Seismic Inversion with Direct Sequential Simulation and Co-simulation with Multi-local Distribution Functions

Stochastic sequential simulation is a common modelling technique used in Earth sciences and an integral part of iterative geostatistical seismic inversion methodologies. Traditional stochastic sequential simulation techniques based on bi-point statistics assume, for the entire study area, stationarity of the spatial continuity pattern and a single probability distribution function, as revealed by a single variogram model and inferred from the available experimental data, respectively. In this paper, the traditional direct sequential simulation algorithm is extended to handle non-stationary natural phenomena. The proposed stochastic sequential simulation algorithm can take into consideration multiple regionalized spatial continuity patterns and probability distribution functions, depending on the spatial location of the grid node to be simulated. This work shows the application and discusses the benefits of the proposed stochastic sequential simulation as part of an iterative geostatistical seismic inversion methodology in two distinct geological environments in which non-stationarity behaviour can be assessed by the simultaneous interpretation of the available well-log and seismic reflection data. The results show that the elastic models generated by the proposed stochastic sequential simulation are able to reproduce simultaneously the regional and global variogram models and target distribution functions relative to the average volume of each sub-region. When used as part of a geostatistical seismic inversion procedure, the retrieved inverse models are more geologically realistic, since they incorporate the knowledge of the subsurface geology as provided, for example, by seismic and well-log data interpretation.     

Brown algae overproduce cell wall polysaccharides as a protection mechanism against the heavy metal toxicity

Brown algae are often used as heavy metal biomonitors and biosorbents because they can accumulate high concentrations of metals. Cation-exchange performed by cell wall polysaccharides is pointed out as the main chemical mechanism for the metal sequestration. Here, we biochemically investigated if the brown alga Padina gymnospora living in a heavy metal contaminated area would modify their polysaccharidic content. We exposed non-living biomass to Cd and Pb and studied the metals adsorption and localization. We found that raw dried polysaccharides, sulfate groups, uronic acids, fucose, mannose, and galactose were significantly higher in contaminated algae compared with the control ones. Metal concentrations adsorbed by non-living biomass were rising comparatively to the tested concentrations. Electron microscopy showed numerous granules in the cell walls and X-ray microanalysis revealed Cd as the main element. We concluded that P. gymnospora overproduces cell wall polysaccharides when exposed to high metal concentrations as a defense mechanism.     

CI-Miner: semantically enhancing scientific processes

The realization of an international cyberinfrastructure of shared resources to overcome time and space limitations is challenging scientists to rethink how to document their processes. Many known scientific process requirements that would normally be considered impossible to implement a few years ago are close to becoming a reality for scientists, such as large scale integration and data reuse, data sharing across distinct scientific domains, comprehensive support for explaining process results, and full search capability for scientific products across domains. This article introduces the CI-Miner approach that can be used to aggregate knowledge about scientific processes and their products through the use of semantic annotations. The article shows how this aggregated knowledge is used to benefit scientists during the development of their research activities. The discussion is grounded on lessons learned through the use of CI-Miner to semantically annotate scientific processes in the areas of geo-sciences, environmental sciences and solar physics: A use case in the field of geo-science illustrates the CI-Miner approach in action.     

Electrochemical Ozone Production as an Environmentally Friendly Technology for Water Treatment

Perspectives, advances and environmental aspects concerning electrochemical ozone production applied to water purification are presented and discussed in relation to the conventional corona process (silent electric discharge). Ozone generated using a laboratory‐made electrochemical reactor was applied for the discoloration/degradation of dyes used in the Brazilian textile industry and for degradation of endocrine disruptors. A constant ozone load of 0.35 ± 0.02 g/h was used throughout. The study, concerning color removal from dye solutions, revealed that total discoloration is rapidly achieved. The degradation rate of the textile dyes evaluated by TOC is little affected by the dye composition and considerably influenced by the pH and ozonation time. Analysis of the COD/TOC‐ratio indicates that ozonation increases oxidation feasibility of the organic matter (dye by‐products) when compared to the original compounds. Ozonation of mixed aqueous solutions containing different endocrine disruptors revealed these compounds are totally degraded with a very high removal rate.     

Geostatistical seismic Amplitude‐versus‐angle inversion

Seismic inversion plays an important role in reservoir modelling and characterisation due to its potential for assessing the spatial distribution of the sub‐surface petro‐elastic properties. Seismic amplitude‐versus‐angle inversion methodologies allow to retrieve P‐wave and S‐wave velocities and density individually allowing a better characterisation of existing litho‐fluid facies. We present an iterative geostatistical seismic amplitude‐versus‐angle inversion algorithm that inverts pre‐stack seismic data, sorted by angle gather, directly for: density; P‐wave; and S‐wave velocity models. The proposed iterative geostatistical inverse procedure is based on the use of stochastic sequential simulation and co‐simulation algorithms as the perturbation technique of the model parametre space; and the use of a genetic algorithm as a global optimiser to make the simulated elastic models converge from iteration to iteration. All the elastic models simulated during the iterative procedure honour the marginal prior distributions of P‐wave velocity, S‐wave velocity and density estimated from the available well‐log data, and the corresponding joint distributions between density versus P‐wave velocity and P‐wave versus S‐wave velocity. We successfully tested and implemented the proposed inversion procedure on a pre‐stack synthetic dataset, built from a real reservoir, and on a real pre‐stack seismic dataset acquired over a deep‐water gas reservoir. In both cases the results show a good convergence between real and synthetic seismic and reliable high‐resolution elastic sub‐surface Earth models.