Chemical composition, sources, solubility, and transport of aerosol trace elements in a tropical region

Aerosol particle samples (PM10) were collected at urban, industrial and rural sites located in Rio de Janeiro, Brazil, between October 2008 and September 2009. Aerosol samples for each site were analyzed for total and soluble metals, water-soluble ions, carboxylic acids, and water-soluble organic carbon (WSOC). The results showed that the mean PM10 concentrations were 34 μg m(-3); 47 μg m(-3) and 71 μg m(-3) at the rural, urban and industrial sites, respectively. An increase in the average concentration of these particles due to air stagnation was observed during the period from May to September for all sites, and an increase in hospitalization for respiratory problems was also reported. On average, the anions species represented 4 to 14% of total content, while cations species corresponded to 1 to 11% and 7.5% for WSOC. The overall metal content at the industrial site was nearly the double that at the rural site. The concentrations of the studied species are influenced mainly by site location and the specific characteristics present at each site. However, higher concentrations of some species were observed on particular dates and were probably due to biomass burning and African dust events. The acid/aqueous percentiles showed that the most efficiently extracted metals from the aqueous phase were V and Ni (40%), while Al and Fe represented a lower percentage (<3%). Analysis of the aqueous fraction provides important information about the bioavailability of metals that is associated with the inflammatory process in the lungs.     

UV-irradiation and BDD-based photoelectrolysis for the treatment of halosulfuron-methyl herbicide

Environmental Science and Pollution Research - This paper reports the development of a novel photoelectrochemical (PEC) oxidation technique based on UV-C irradiation and boron-doped diamond (BDD)...     

Towards a cleaner production in developing countries: a case study in a Chilean tannery.

A Chilean leather tanning industry (tannery) was studied in terms of input/output (I/O) analysis of beamhouse, tanyard and retanning processes. The physical-chemical characterization of 19 streams were investigated. Streams from the beamhouse process and some streams from the retanning process were found to have high organic contents ranging from 2.5 to 18.1 g COD L(-1). The pH ranged between 3.45 and 12.28. Sulphur was found in most of the streams whereas chromium was detected in two wastewaters from the tanyard and in seven streams from the retanning process. Pollution prevention opportunities were evaluated and an appropriate treatment strategy was proposed. The main emphasis was on determining waste reduction measures that can be easily implemented and are not particularly expensive. Measures for reduction at source were proposed to reduce water and chemicals consumption and wastewater pollution. A so-called S(index) strategy was used to evaluate proposals on segregation and specific treatment of the main chromium- and sulphur-containing wastewaters. It was suggested that some streams may be re-used, but it is necessary to apply anaerobic or aerobic treatment first, depending on their organic load. Solid wastes were also evaluated and a proposal for their reduction and disposal was made.     

Population density and conservation status of the teiid lizard <Emphasis Type="Italic">Cnemidophorus littoralis</Emphasis>, an endangered species endemic to the sandy coastal plains (restinga habitats) of Rio de Janeiro state,Brazil

The threatened lizard Cnemidophorus littoralis occurs in only four restinga habitats of Brazilian coast and its current conservation status is “endangered”. Due to its restricted distribution, the effects of habitat degradation are especially harmful to them. To prevent a local or even total extinction, we analyzed changes in population density and in amount of disturbances of three restinga areas during a seven-year gap. This study took place in three restingas of Rio de Janeiro State, Brazil: Maricá, Jurubatiba and Grussaí. We compared C. littoralis current density with the one registered in 2005 by Menezes and Rocha (2013) with 2 ha transections in each restinga. We also made another group of transects to estimate population density along the entire extension of the restingas. Conservation index of each site was based on satellite images and field samplings. Data showed a decreasing trend of Cnemidophorus littoralis population density over the years. Grussaí had the lowest population density and the highest degradation index among the three sites, whereas Jurubatiba had the lowest degree of disturbance, the largest area and the highest lizard population density. Data showed an increase in the amount of disturbance in restingas over the years, which seemed to have a negative effect in C. littoralis population density. Improvement of surveillance and implementation of education programs in the protected areas and its surroundings, and periodic monitoring of C. littoralis populations to follow their density changes, are essential for the maintenance of the species.     

Effect of MgO and CaO/SiO2 on the immobilization of chromium in synthetic slags

This work investigated the chemical and mineralogical properties of CaO–SiO₂–Cr₂O₃–CaF₂–MgO slags. Synthetic slags were prepared and the effect of the slag basicity (mass ratio CaO/SiO₂) and MgO contents on the stability of the mineralogical species formed was analyzed. The morphology and composition of the slags were analyzed by X-ray powder diffraction (XRD) and scanning electron microscope-energy dispersive spectroscopy (SEM–EDS), whilst their chemical stability was evaluated by leaching with an aqueous acetic acid solution. It was found that in slags with CaO/SiO₂?=?1, the main Cr-compound was MgCr₂O₄ spinel, which forms octahedron crystals. Small amounts of CaCr₂O₄ and CaCrO₄ were also observed. It was found that with increasing the slag basicity from 1 to 2 the compounds MgCr₂O₄ and CaCr₂O₄ were formed together with the Cr(V)-containing compound complex Ca₅(CrO₄)₃F which forms hexagonal crystals. The results showed that the highest Cr concentration levels in the leaching liquors corresponded to slags with CaO/SiO₂?=?2, probably owing to the formation of CaCrO₄ and Ca₅(CrO₄)₃F, whilst the lowest chromium concentration levels corresponded to MgO-based slags owing to the stable binding of chromium in spinel with MgO. Additionally, potential–pH diagrams for the Ca–Cr–H₂O and Mg–Cr–H₂O systems at 25?°C were calculated.     

Safety culture: analysis of the causal relationships between its key dimensions

INTRODUCTION: Several fields are showing increasing interest in safety culture as a means of reducing accidents in the workplace. The literature shows that safety culture is a multidimensional concept. However, considerable confusion surrounds this concept, about which little consensus has been reached. METHOD: This study proposes a model for a positive safety culture and tests this on a sample of 455 Spanish companies, using the structural equation modeling statistical technique. RESULTS: Results show the important role of managers in the promotion of employees' safe behavior, both directly, through their attitudes and behaviors, and indirectly, by developing a safety management system. IMPACT ON INDUSTRY: This paper identifies the key dimensions of safety culture. In addition, a measurement scale for the safety management system is validated. This will assist organizations in defining areas where they need to progress if they wish to improve their safety. Also, we stress that managers need to be wholly committed to and personally involved in safety activities, thereby conveying the importance the firm attaches to these issues.     

Remediation effect of compost on soluble mercury transfer in a crop of Phaseolus vulgaris

We studied the dynamics of mercury (Hg) transfer in Phaseolus vulgaris plants grown in soil with Hg-doped compost at the maximum levels permitted by Colombian law on organic amendments. Quantitative evaluation of transfer was made in different plant organs: roots, stem, leaves, pods and seeds. Matrix effect was determined in doped soil assays, using soil with and without addition of compost. Results showed that the use of organic matter reduced Hg transfer to the plant and the amount transferred was differentially distributed to the organs. We observed an inverse relationship between concentration and distance from the body to the root. It was evident that transfer was mediated by quantitative factors; the greater the presence of mercury in soil, the larger the amount that will be transferred. Results also indicate the remedial effect of compost and the presence of a barrier, at the root level, against mercury translocation to the plant aerial parts.     

Arsenic release from pyrite ash waste over an active hydrogeological system and its effects on water quality

Environmental Science and Pollution Research - Arsenic is a potentially toxic element of concern for environmental compartments, and it is a frequent pollutant in many abandoned industrial sites....     

Synthesis of Polymeric Matrices for Adsorption and Purification of Endoglucanase

Chitosan (CHS), chitosan–Eudragit® EPO (CHS–EPO) and chitosan beads partially cross-linked with glutaraldehyde (CHS–GLUT) were obtained in order to improve the adsorption selectivity of endoglucanase from a fungal culture obtained under SSF by Aspergillus niger using soybean harvest residues as support. The matrices synthetized were characterized in terms of physical and chemical changes. Fourier-transformed infrared spectroscopy with attenuated total reflectance device (FTIR-ATR) was employed to verify the chemical changes on the CHS matrix after the synthesis of CHS–GLUT and CHS–EPO. Scanning electron microscopy (SEM) was performed to compare the surface morphology of the polymeric beads. Two variables, purification factor and yield percentage of the adsorption process, were analyzed using a bifactorial ANOVA considering the matrix–time first order interaction. SEM results exhibited greater surface roughness in the CHS–GLUT and CHS–EPO matrices which may enhance endoglucanase adsorption. FTIR-ATR results confirmed an effective chemical modification of the CHS matrix after crosslinking with GLUT and corroborated the efficiency of the synthesis of the CHS–EPO matrix by the presence of chemical groups of the EPO polymer. An endoglucanase purification factor close to 9 was achieved with the CHS–GLUT matrix and a yield percentage of 60% was obtained with the CHS–EPO matrix. Bifactorial ANOVA results showed the matrix–time interaction to be significant for both variables. The CHS–GLUT matrix with low crosslinking times and the novel CHS–EPO matrix could be included in the bioseparation stage of endoglucanase using a simple and a low-cost method such as batch adsorption.     

Impact of land-cover change in the Southern Amazonia climate: a case study for the region of Alta Floresta,Mato Grosso,Brazil

The transformation of forest into pastures in the Brazilian Amazon leads to significant consequences to climate at local scale. In the region of Alta Floresta (Mato Grosso, Brazil), deforestation has been intense with over half the forests being cut since 1970. This article first examines the evolution of precipitation observed in this region and shows a significant trend in the decrease in total precipitation especially at the end of the dry season and at the beginning of the rainy season. The study then compares the temperatures measured in cleared and forested sectors within a reserve in the area of Alta Floresta (Mato Grosso, Brazil) between 2006 and 2007. The cleared sector was always hotter and drier (from 5% to 10%) than the forested area. This difference was not only especially marked during the day when it reached on average 2°C but also seemed to increase during the night with the onset of the dry season (+0.5°C). The Urban Heat Island effect is also evident especially during the night and in the dry season.