Production of soybean ethanol-based biodiesel using CaO heterogeneous catalysts promoted by Zn,K and Mg

This article focuses on the optimization of the production of fatty acid ethyl esters from soybean oil using CaO-based heterogeneous catalysts. Three different catalytic promoters were evaluated: Magnesium, zinc, and potassium. The reaction has evaluated the promoter content (promoter to calcium molar ratio), catalyst load, alcohol to oil molar ratio, and temperature. Response surface methodology (RSM) was used to evaluate the influence of each variable on the yield of biodiesel. The addition of K₂O or MgO in the catalyst has enhanced the yield in fatty acid ethyl esters, while the use of ZnO as a promoter was not successful.     

Contribution of sociodemographic characteristics, occupation, diet and lifestyle to DDT and DDE concentrations in serum and adipose tissue from a Bolivian cohort

The organochlorine pesticide p,p′-Dichlorodiphenyltrichloroethane (DDT) was widely used in the early 1960s-70s for vector control in tropical and subtropical areas of South America. Due to its persistence, DDT has a high potential to bioaccumulate in the food chain and living organisms and is a major public health concern, especially in South America.The main purpose of the present study was to investigate predictors of serum and adipose tissue concentrations of p,p′-DDT and its main metabolite, p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE), in an adult cohort (n = 112) from Santa Cruz de la Sierra, Bolivia, using multiple linear regression models. These models explained 29.3-47.8% of the variability in adipose tissue concentrations of p,p′-DDT and p,p′-DDE, respectively, and 32.9-47.0% of that in serum. Main exposure predictors included age, occupational class, residence, diet, smoking habit, and accumulated breastfeeding time.This is one of the few studies to explore predictors of human exposure to these chemicals using a multivariate approach in a South American population. Results show that predictors of human exposure to p,p′-DDT and p,p′-DDE in Santa Cruz de la Sierra may diverge from those found in other populations of the world, due to particular sociodemographic and lifestyle characteristics of this region.     

Assessing Tourists' Preferences for Recreational and Environmental Management Programs Central to the Sustainable Development of a Tourism Area in the Dominican Republic

The main goals of this paper are to (1) highlight the need for sustainable development as a means to conserve natural resources and the environment, which often represent the basis for tourism development, (2) illustrate the importance of assessing tourists' preferences when designing programs and policies central to the sustainable development of a tourism area, and (3) study tourists' interests in sustainable development. With these goals in mind, 180 tourists from Europe, Latin America, and North America were interviewed as they were leaving the resort region of Punta Cana in the Dominican Republic. The main factors that they considered when deciding where to go on a beach vacation were evaluated, as well as their preferences regarding four programs designed to improve recreational and environmental management of the area. Preferences by tourists were elicited both in monetary and non-monetary terms. This paper reports the non-monetary analysis of the data. The results indicate that clean ocean water and beaches, quality of services, and price are the most important factors considered by the respondents before deciding to come to Punta Cana. It was not possible to obtain reliable responses on how tourists perceived the four programs contributing to the sustainable development of Punta Cana. Nevertheless, they expressed high interest and willingness to pay for two of these programs: the outdoor aquarium and the Water Management Program. The results reported in this paper show how important it is to elicit tourists' preferences of programs central to the sustainable development of tourism areas since these preferences can drive managers' development decisions in more sustainable directions.     

Iron oxide nanoparticles embedded in organic microparticles from Yerba Mate useful for remediation of textile wastewater through a photo-Fenton treatment: Ilex paraguariensis as a platform of environmental interest – Part 1

Environmental Science and Pollution Research - Seven composites of iron oxide nanoparticles embedded in organic microparticles mediated by Cu(II) were synthesized using yerba mate (Ilex...     

Using spatial patterns in illegal wildlife uses to reveal connections between subsistence hunting and trade

Although most often considered independently, subsistence hunting, domestic trade, and international trade as components of illegal wildlife use (IWU) may be spatially correlated. Understanding how and where subsistence and commercial uses may co‐occur has important implications for the design and implementation of effective conservation actions. We analyzed patterns in the joint geographical distribution of illegal commercial and subsistence use of multiple wildlife species in Venezuela and evaluated whether available data were sufficient to provide accurate estimates of the magnitude, scope, and detectability of IWU. We compiled records of illegal subsistence hunting and trade from several sources and fitted a random‐forest classification model to predict the spatial distribution of IWUs. From 1969 to 2014, 404 species and 8,340,921 specimens were involved in IWU, for a mean extraction rate of 185,354 individuals/year. Birds were the most speciose group involved (248 spp.), but reptiles had the highest extraction rates (126,414 individuals/year vs. 3,133 individuals/year for birds). Eighty‐eight percent of international trade records spatially overlapped with domestic trade, especially in the north and along the coast but also in western inland areas. The distribution of domestic trade was broadly distributed along roads, suggesting that domestic trade does not depend on large markets in cities. Seventeen percent of domestic trade records overlapped with subsistence hunting, but the spatial distribution of this overlap covered a much larger area than between commercial uses. Domestic trade seems to respond to demand from rural more than urban communities. Our approach will be useful for understanding how IWU works at national scales in other parts of the world.     

Single drop microextraction and gas chromatography–mass spectrometry for the determination of diflufenican, mepanipyrim, fipronil, and pretilachlor in water samples

An analytical method for the determination of diflufenican, mepanipyrim, pretilachlor, and fipronil in water samples was developed using single drop microextraction in the direct immersion mode and gas chromatography–mass spectrometry. A factorial fractionated design of type 2^6–1 at two levels was performed, to study the influence of experimental variables such as ionic strength, pH, agitation speed, extraction time, drop volume, and sample volume. To establish the optimal conditions for the variables that were significant, a Doehlert design was performed. The optimum conditions of extraction were 1 μL of heptane immersed in 4.0 mL of sample with continuous agitation at 500 rpm for 30 min at room temperature. The developed method proved to have good linearity for the range studied. The detection limits were 0.07 μg L^?1 for diflufenican, 0.03 μg L^?1 for mepanipyrim, 0.08 μg L^?1 for pretilachlor, and 1.39 μg L^?1 for fipronil. The method was validated on river water samples, showing the absence of matrix effect and recoveries ranged from 90.1 to 107.8 %. The results show that the method developed is accurate, sensitive, rapid, simple, and low cost, so it is recommended for application in the analysis of these different classes of pesticides in water samples.     

Resprouting as a persistence strategy of tropical forest trees: relations with carbohydrate storage and shade tolerance

Resprouting is an important persistence strategy for woody species and represents a dominant pathway of regeneration in many plant communities, with potentially large consequences for vegetation dynamics, community composition, and species coexistence. Most of our knowledge of resprouting strategies comes from fire-prone systems, but this cannot be readily applied to other systems where disturbances are less intense. In this study we evaluated sapling responses to stem snapping for 49 moist-forest species and 36 dry-forest species from two Bolivian tropical forests. To this end we compared in a field experiment the survival and height growth of clipped and control saplings for a two-year period, and related this to the shade tolerance, carbohydrate reserves, and the morphological traits (wood density, leaf size) of the species. Nearly all saplings resprouted readily after stem damage, although dry-forest species realized, on average, a better survival and growth after stem damage compared to moist-forest species. Shade-tolerant species were better at resprouting than light-demanding species in moist forest. This resprouting ability is an important prerequisite for successful regeneration in the shaded understory, where saplings frequently suffer damage from falling debris. Survival after stem damage was, surprisingly, only modestly related to stem reserves, and much more strongly related to wood density, possibly because a high wood density enables plants to resist fungi and pathogens and to reduce stem decay. Correlations between sampling performance and functional traits were similar for the two forest types, and for phylogenetically independent contrasts and for cross-species analyses. The consistency of these results suggests that tropical forest species face similar trade-offs in different sites and converge on similar sets of solutions. A high resprouting ability, as well as investments in stem defense and storage reserves, form part of a suite of co-evolved traits that underlies the growth-survival trade-off, and contributes to light gradient partitioning and species coexistence. These links with shade tolerance are important in the moist evergreen forest, which casts a deep, more persistent shade, but tend to diminish in dry deciduous forest where light is a less limiting resource.     

Photosynthetic oxygen production and PAM fluorescence in the brown algaPadina pavonica measured in the field under solar radiation

The effects of solar radiation on photosynthetic oxygen production, pulse amplitude-modulated (PAM) fluorescence and pigmentation were measured in the Mediterranean brown macroalgaPadina pavonica (Linnaeus) Lamouroux under field conditions and natural sunlight. Exposure of thalli to solar radiation for 1 h caused a dramatic decrease of their photosynthetic quantum yield, which recovered to initial levels after they had been placed in the shade for 3 h. Photoinhibition also occurred at the natural growth site ofP. pavonica during the hours of maximal solar irradiance. Photosynthetic oxygen production was also affected by high levels of solar radiation both in algae harvested from the surface and from 6 m depth; oxygen production started to decrease after a few minutes of exposure, and negative values were found after 1 h of solar exposure. Chlorophylla content inP. pavonica also decreased during the hours of maximal solar irradiation. These results suggest that photoinhibition ofP. pavonica occurs during part of a typical summer day on Mediterranean coasts.     

Carbon dots decorated magnetite nanocomposite obtained using yerba mate useful for remediation of textile wastewater through a photo-Fenton treatment: Ilex paraguariensis as a platform of environmental interest—part 2

Environmental Science and Pollution Research - Two carbon dots (CD) with diameters of 4.9?±?1.5 and 4.1?±?1.2 nm were successfully synthesized through an...     

Use of Lens culinaris Med test as environmental bioindicator to identify the cytogenotoxic effect of paraquat pesticide

Environmental Science and Pollution Research - Paraquat is the most widely used herbicide and the third most sold pesticide in the world, applied in more than 120 countries despite being banned in...