Patterns of distribution and composition of sea urchin assemblages on Brazilian subtropical rocky reefs

Sea urchins are a key group of herbivores in both temperate and tropical food webs because they control macroalgal cover, and consequently influence primary productivity and phase shifts on reefs. Despite being abundant on southwestern Atlantic reefs, sea urchin distributions, and their association with abiotic and biotic variables, are poorly known. In this study, sea urchin assemblages were surveyed in 2011 at multiple depths at eight sites in Arraial do Cabo (Brazil, 22°57′S/41°01′W), with sites split between a colder, more wave-exposed location, and a warmer, more sheltered location. The influence of this large-scale physical gradient, along with changes in depth and substrate complexity, on sea urchin densities was then investigated. Predator biomass was low and did not vary significantly among sites. Among the seven species recorded, Paracentrotus gaimardi, Echinometra lucunter and Arbacia lixula were dominant. Linear mixed-effects models indicated that location was important, with mid-sized P. gaimardi individuals and A. lixula more common at cooler, exposed sites and E. lucunter more abundant at warmer, sheltered sites. Sea urchin densities typically decreased with increasing depth, probably caused by changes in factors such as light, wave exposure, and sedimentation. Substrate complexity had a positive effect on the abundance of all species, presumably because of the increased availability of refuges. Physical gradients have important consequences for urchin distributions and their ecological functions at relatively small spatial scales on these reefs, and should be incorporated into herbivore monitoring programmes. Research is also required to examine how differential sea urchin distributions affect benthic dynamics.     

Numerical and wind tunnel modeling on the windbreak effectiveness to control the aeolian erosion of conical stockpiles

There are many industrial sites where open aggregate conical piles exist to store granular materials, like coal, industrial residuals, or other minerals. Usually these storage piles are placed in open areas, making them susceptible to wind erosion, which can create health, environmental, and/or economical concerns. It is common to minimize the dust emission through the placement of windbreaks in the vicinity of the storage piles, which reduces the wind speed in the vicinity of the pile’s surface. In this work, some experimental results from a wind tunnel study on the erosion of a conical sand pile, exposed or protected by a fence with porosities of 0, 70, and 83%, are shown. For the sheltered cases, the windbreak was placed at several distances from the pile’s leading edge, ranging from H to 4H, where H is the initial height of the non-eroded pile. The evolution of the shape of the sand pile is shown, at different instances in time, and the pile deformation quantified, using a novel experimental setup developed for wind erosion studies. This information might be regarded as a useful dataset for the benchmark of computational models aiming to produce the transient simulation of the aeolian erosion of stockpiles. The CFD results are comprised of the modeling of several experimental scenarios. The computational results for the surface wind velocity show a good correlation with the initial deformation of the pile. Based on the results, the isocontours of (u _s /u _r ) presented might be regarded as a good basis for the estimation of the pile shear velocity.     

Micronucleus study of the quality and mutagenicity of surface water from a semi-arid region

The present study evaluated the mutagenic potential of surface water from the Lucrecia dam. The Tradescantia-micronucleus (Trad-MCN) test and CBMN assay in human peripheral blood lymphocytes were applied, corresponding to an in vivo and in vitro system, respectively. Heavy metals and some physicochemical properties were also measured. Water samples were collected in November 2009 (dry season) and May 2010 (rainy season) at three different points. Results of both assays for raw water showed positive responses for the points analyzed when compared to the negative control. The CBMN assay showed that diluted water was still able to induce a significant increase in micronucleus frequency. For both assays, the highest mean MN was observed in the dry season. Chemical analyses detected an increase in heavy metal levels at the sampling points and in the different seasons. These findings indicate the presence of genotoxins, such as heavy metals, in the water, which may be affecting the entire ecosystem, as well as human health. More prolonged monitoring is recommended in order to better characterize this public water supply.     

Wave-like motion and secondary currents in arrays of emergent cylinders induced by large scale eddying motion

Environmental Fluid Mechanics - Free-surface flows with riparian corridors are known to develop large eddies resulting from the instability associated to the inflectional profile of the...     

Biosorption of uranium from aqueous solutions by Azolla sp. and Limnobium laevigatum

Environmental Science and Pollution Research - The main goal of this study was to assess alternatives to the current challenges on environmental quality and circular economy. The former is here...     

Factors driving sediment compositional change in the distal area of the Ria de Vigo (NW Spain): oceanographic processes vs. paleopollution

Environmental Science and Pollution Research - We analyze potential Late Holocene metal contamination along a sediment core collected in the distal zone of Ria de Vigo (North Spain). Statistical...     

Educating citizens about their coastal environments: beach profiling in the Coastwatch project

The Coastwatch (CW) project is aimed at monitoring the coastline with the involvement of volunteers. Between 2003 and 2007 a beach profiling method was informally proposed to CW participants in Portugal as an extra activity to include in the surveys. Beach profiling contributes to a better understanding of coastal processes by providing quantitative information on the spatial/temporal evolution of beaches, which is crucial for coastal management. The profiling method proposed to the CW project is based on the physical principle of communicating vessels, and only requires a simple and inexpensive homemade ??profiler??. The simplicity of putting together and using the profiler, added to the arithmetic straightforwardness of data analysis, makes this method adequate for several kinds of users and for most levels of education. Eight workshops were held that included a classroom explanation of the method, the construction of a profiler, the actual profiling of a beach, and a final classroom session of data processing and graphing. About 140 participants received such training, and several among them independently undertook beach profiling. Surveyed participants found the workshop and the beach profiling method interesting and useful, and considered it a valuable tool for teaching and for management. External stakeholders (coastal managers) highlighted the importance of beach profiling data for management decisions and considered that this method produces robust data, even when carried out by volunteers. Further advantages of the application of the method, in the context of coastal management initiatives, for scientists, managers, and volunteers are discussed.     

Dengue, related to rubble and building construction in Brazil

The fast-growing formation of solid waste, resulting from demographic density, presents itself as one of the most pressing problems to be addressed by governments of large cities all over the world. In Rio de Janeiro, 60% of solid waste stems from the construction industry. Although envisaged by under current municipal legislation, no application of policy regarding systematic recycling of this kind of waste exists in fact. Both sanitation experts and epidemiologists highlight that the deficient sanitary system contributes to the growth of endemic breeding sites, which may reach epidemic proportions. In Brazil, over the recent years, there has been an increase of Dengue Fever cases followed by deaths. In the first half of 2008, the State of Rio de Janeiro was plagued by an intense Dengue epidemic. The city of Rio de Janeiro alone accounted for 48.7% of the cases, in absolute values. By drawing upon an analytical method based on the interrelation between health and sanitation, the outcomes herein indicate that the city of Rio de Janeiro bears a direct relation between Dengue incidence rates and rubble formation from construction – measured by the total area built. Thus, there is a strong urge to implement recycling systems out of construction rubble as a sanitation measure in order to promote Dengue incidence reduction.     

Utilization of kaolin processing waste for the production of porous ceramic bodies

The kaolin processing industry generates large amounts of waste in producing countries such as Brazil. The aim of this study was to characterize kaolin processing waste and evaluate its suitability as an alternative ceramic raw material for the production of porous technical ceramic bodies. The waste material was physically and chemically characterized and its thermal behaviour is described. Several formulations were prepared and sintered at different temperatures. The sintered samples were characterized to determine their porosity, water absorption, firing shrinkage and mechanical strength. Fired samples were microstructurally analysed by X-ray diffraction and scanning electron microscopy. The results indicated that the waste consisted of quartz, kaolinite, and mica, and that ceramic formulations containing up to 66% of waste can be used for the production of ceramics with porosities higher than 40% and strength of about 70 MPa.     

Separation of packaging plastics by froth flotation in a continuous pilot plant

The objective of the research was to apply froth flotation to separate post-consumer PET (Polyethylene Terephthalate) from other packaging plastics with similar density, in a continuously operated pilot plant. A representative sample composed of 85% PET, 2.5% PVC (Polyvinyl Chloride) and 11.9% PS (Polystyrene) was subjected to a combination of alkaline treatment and surfactant adsorption followed by froth flotation. A mineral processing pilot plant, owned by a Portuguese mining company, was adapted for this purpose. The experimentation showed that it is possible to produce an almost pure concentrate of PET, containing 83% of the PET in feed, in a single bank of mechanical flotation cells. The concentrate grade attained was 97.2% PET, 1.1% PVC and 1.1% PS. By simulation it was shown that the Portuguese recycling industry specifications can be attained if one cleaning and one scavenger stages are added to the circuit.