Catalytic combustion of soot over ceria-zinc mixed oxides catalysts supported onto cordierite

Modified substrates as outer heterogeneous catalysts was employed to reduce the soot generated from incomplete combustion of diesel or diesel/biodiesel blends, a process that harms the environment and public health. The unique storage properties of ceria(CeO2) makes it one of the most efficient catalysts available to date. Here, we proposed that ceria-based catalysts can lower the temperature at which soot combustion occurs; more specifically, from 610℃ to values included in the diesel exhausts operation range(300–450℃). The sol-gel method was used to synthesize mixed oxide-based catalysts(CeO2:ZnO); the resulting catalysts were deposited onto cordierite substrates. In addition, the morphological and structural properties of the material were evaluated by XRD, BET, TPR-H2, and SEM. Thermogravimetric(TG/DTA) analysis revealed that the presence of the catalyst decreased the soot combustion temperature by 200℃ on average, indicating that the oxygen species arise at low temperatures in this situation, promoting highly reactive oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy(DRS) showed that catalyst-impregnated cordierite samples efficiently oxidized soot in a diesel/biodiesel stationary motor: soot emission decreased by more than 70%.     

The effects of sport fishing growth on behavior of commercial fishermen in Balbina reservoir, Amazon, Brazil

An important alternative for sustainable use of tucunaré stocks and improvement in fishermen welfare in Balbina reservoir, Central Amazon, would be to train commercial fisherman to also become tourist guides for sport fishing. In this study, we modeled fishermen response to this question, in order to evaluate the acceptance of such an idea. Thus, we surveyed 47 fishermen, who currently comprise approximately 75% of the total fishermen population. This survey was implemented during December of 2001 and January of 2002. We used a probity analysis to run two models. The first model includes the variables: family size, school level, fishing time, residence time and boat ownership. On the other hand, the second model includes the number of children under and above eight years old but not the family size. Both models are significant and the most relevant variables are: fishing time (years of participation of fisherman is in the activity) and residence time (length of residency of particular fishermen live at the village nearby the reservoir).     

Evaluation of the geotechnical properties of MSW in two Brazilian landfills

The characteristics of municipal solid waste (MSW) play a key role in many aspects of waste disposal facilities and landfills. Because most of a landfill is made up of MSW, the overall stability of the landfill slopes are governed by the strength parameters and physical properties of the MSW. These parameters are also important in interactions involving the waste body and the landfill structures: cover liner, leachate and gas collection systems. On the other hand, the composition of the waste, which affects the geotechnical behavior of the MSW, is dependent on a variety of factors such as climate, disposal technology, the culture and habits of the local community. It is therefore essential that the design and stability evaluations of landfills in each region be performed based on the local conditions and the geotechnical characteristic of the MSW. The Bandeirantes Landfill, BL, in São Paulo and the Metropolitan Center Landfill, MCL, in Salvador, are among the biggest landfills in Brazil. These two disposal facilities have been used for the development of research involving waste mechanics in recent years. Considerable work has been made in the laboratory and in the field to evaluate parameters such as water and organic contents, composition, permeability, and shear strength. This paper shows and analyzes the results of tests performed on these two landfills. The authors believe that these results could be a good reference for certain aspects and geotechnical properties of MSW materials in countries with similar conditions.     

Effects of soil attributes and straw accumulation on the sorption of hexazinone and tebuthiuron in tropical soils cultivated with sugarcane

Brazil is the largest sugarcane producer in the world in which hexazinone (3-cyclohexyl-6-dimethylamino-1-methyl-1,3,5-triazine-2,4-dione) and tebuthiuron (1-(5-tert-butyl-1,3,4-thiadiazol-2-yl)-1,3-dimethylurea) are heavily used. Sugarcane harvesting is changing from the manual system with previous straw burning to the mechanized system without straw burning. The lack of burning results in soil organic carbon accumulation mainly in clayey soils, which should affect herbicides availability and fate. Therefore, we evaluated sorption of these herbicides in soil samples with and without straw burning. Both herbicides presented low apparent sorption coefficients (mean K_d,app= 0.6 and 2.4 L kg^?1 for hexazinone and tebuthiuron, respectively), suggesting that they may leach to groundwater. Moreover, their sorption correlated primarily with soil organic carbon (SOC), but iron oxide contents extracted with ammonium oxalate (Fe₂O₃^AOX) also affected it (K_d,app = ?0.228 + 0.0397 SOC + 0.117 Fe₂O₃^AOX for hexazinone and K_d,app = ?1.407 + 0.201 SOC + 0.348 Fe₂O₃^AOX for tebuthiuron). Soil organic carbon accumulation due to straw maintenance in the field positively affected sorption of both herbicides, but its effects were not enough to classify them as “non-leachers.”     

Chemometric tools applied to optimize a fast solid-phase microextraction method for analysis of polycyclic aromatic hydrocarbons in produced water

Environmental Science and Pollution Research - Chemometric tools are powerful strategies to efficiently optimize many processes. These tools were employed to optimize a fast-solid phase...     

Regression models for exceedance data via the full likelihood

Many situations in practice require appropriate specification of operating characteristics under extreme conditions. Typical examples include environmental sciences where studies include extreme temperature, rainfall and river flow to name a few. In these cases, the effect of geographic and climatological inputs are likely to play a relevant role. This paper is concerned with the study of extreme data in the presence of relevant auxiliary information. The underlying model involves a mixture distribution: a generalized Pareto distribution is assumed for the exceedances beyond a high threshold and a non-parametric approach is assumed for the data below the threshold. Thus, the full likelihood including data below and above the threshold is considered in the estimation. The main novelty is the introduction of a regression structure to explain the variation of the exceedances through all tail parameters. Estimation is performed under the Bayesian paradigm and includes model choice. This allows for determination of higher quantiles under each covariate configuration and upper bounds for the data, where appropriate. Simulation results show that the models are appropriate and identifiable. The models are applied to the study of two temperature datasets: maxima in the U.S.A. and minima in Brazil, and compared to other related models.     

Do geomagnetic storms change the behaviour of the stingless bee guiruçu (Schwarziana quadripunctata)?

Six behavioural experiments were carried out to investigate the magnetic field effects on the nest-exiting flight directions of the honeybee Schwarziana quadripunctata (Meliponini). No significant differences resulted during six experiment days under varying geomagnetic field and the applied static inhomogeneous field (about ten times the geomagnetic field) conditions. A surprising statistically significant response was obtained on a unique magnetic storm day. The magnetic nanoparticles in these bees, revealed by ferromagnetic resonance, could be involved in the observed effect of the geomagnetic storm.     

Assessment of the hunting of mammals using local ecological knowledge: an example from the Brazilian semiarid region

The hunting of wild animals remains a common activity in various parts of the world, especially in rural communities with poor socioeconomic conditions. To investigate patterns of mammal hunting, this study adopted a rural community located in semiarid Brazil as a model to test whether variables such as perceived abundance, activity period (day or night) and animal biomass could influence the consumption potential of mammal taxa. For this study, a checklist/interview technique using 32 photographs of mammals recorded in the region and two photographs of species that did not occur in the region, which acted as “control” species, was used, in addition to other visual stimuli and free lists. All species presented in the photographs, with the exception of the “control” species, were recognized as occurring in the region. Fourteen species were cited as being those most hunted locally. The species cited as most hunted had an average perceived abundance higher than the group of the least-hunted species. However, there was no significant relationship between hunting of a species and its locally perceived abundance. No significant difference in hunting pressure between diurnal and nocturnal species was found, nor was a relationship between animal biomass and hunting pressure observed. Our findings suggest that perceived abundance is an important factor for choosing a resource fauna, but other factors such as intended use, meat flavor and vulnerability to hunting, among others, may influence the potential use of a species.