Improving the Rheological and Mechanical Properties of Recycled PET Modified by Macromolecular Chain Extenders Synthesized by Controlled Radical Polymerization

In this work, a series of reactive copolymers of glycidyl methacrylate (G), styrene (S) and acrylonitrile (AN), were synthesized through reversible addition-fragmentation chain transfer polymerization and evaluated as macromolecular chain extenders in reactive extrusion of recycled poly(ethylene terephthalate) (rPET). The results obtained indicate that the addition of the reactive copolymers as chain extenders modifies the chain conformation in rPET causing low crystallization rate and low crystallinity. The physical and rheological properties (melt flow and intrinsic viscosity) of chain-extended rPET improved, rendering better processability. rPET modified with polymeric chain extenders shows improved rheological properties (complex viscosity, storage and loss modulus) and also displays higher elongation at break and impact properties as the GMA content in the chain extenders increase.     

Integrated hydro- and wind power generation: a game changer towards environmental flow in the Sub-middle and Lower São Francisco River Basin?

Many renewable resources for the generation of electricity, such as hydropower and wind power, are dependent on climatic factors. Reservoirs have been created to overcome the stochastic nature of river flows and to make water supply more reliable. However, reservoirs are affecting the ecological status of river ecosystems, e.g., by modifying the flow regime, triggering discussions regarding the discharge of reservoirs. In Brazil’s northeast region, the installed capacity for wind power generation has increased substantially in recent years. Setting up a modeling system for simulating wind power and hydropower generation in this study, it is analyzed whether wind power generation, peaking in the dry season, can help to achieve a more environmentally oriented flow regime in the Sub-middle and Lower São Francisco River Basin. Simulated higher discharges from reservoirs during the rainy season and lower discharges during the dry season, representing a more natural flow regime, will reduce hydropower generation in the dry season. Under recent conditions, the resulting gap in electricity generation can only be partially covered by wind power. A large share needs to be generated by thermal power plants or be imported from other regions in Brazil. The planned future increase in installed wind power capacity can change this picture; the demand for electricity generated by thermal power plants and imported will decrease. Adopting an integrated approach for hydropower and wind power generation, the flow regime in the Sub-middle and Lower São Francisco River Basin can be modified to improve the ecological status of the river system.     

Climate change impact on the potential yield of Arabica coffee in southeast Brazil

Regional Environmental Change - The Intergovernmental Panel on Climate Change (IPCC) projections of global mean temperature rises are worrisome for coffee crop due to the intolerance of the Arabica...     

Woody plant encroachment following grazing abandonment in the subalpine belt: a case study in northern Spain

Regional Environmental Change - The montane and subalpine belts in European mountains were affected by intense land use/land cover changes during the twentieth century. In the case of the subalpine...     

Mice exposure to tannery effluents changes their olfactory capacity,and their response to predators and to the inhibitory avoidance test

Environmental Science and Pollution Research - The current study has assessed whether the oral and/or dermal exposure of C57Bl/6 J mice to tannery effluent (a complex pollutant consisting of...     

Oxidative damage to Pseudomonas aeruginosa ATCC 27833 and Staphylococcus aureus ATCC 24213 induced by CuO-NPs

Environmental Science and Pollution Research - The cytotoxicity of nanoparticles (NPs) and their properties are important issues in nanotechnology research. Particularly, NPs affect the metabolism...     

Removal of the emerging contaminant bisphenol A by an ureasil–PEO hybrid membrane: experimental study and molecular dynamic simulation

This work reports the use of a cross-linked ureasil–PEO hybrid matrix (designated PEO800) as an efficient adsorbent to retain the emerging contaminant bisphenol A (BPA) from an aqueous medium. The in-deep experimental and theoretical results provide information about the interactions between PEO800 and BPA. The in situ UV-vis spectroscopy data and the pseudo-first order, pseudo-second order, Elovich, and Morris–Webber intraparticle diffusion models allowed us to propose a three-step mechanism for the adsorption of BPA onto PEO800. The results indicate that the pseudo-first-order kinetic model effectively describes the adsorption of BPA onto PEO800. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy confirmed the interaction of PEO800 with BPA, showing an alteration in the chemical environment of the polymer ether oxygen atoms present in the hybrid matrix. The molecular dynamic simulation provides further evidence that the BPA molecules interact preferentially with PEO. The amount of desorbed BPA depended on the pH and solvent used in the assays. This work provides new opportunities for using the hydrophilic ureasil–PEO matrix which has demonstrated its abilities in being a fast and easy alternative to successfully removing organic contaminants from aqueous mediums and therefore having potential applications in water remediation.

Graphical abstract

     

Effects of sex on the levels of metals and metalloids in the hair of a group of healthy Spanish adolescents (13 to 16 years old)

Human biomonitoring can be a reliable tool to protect the health of the citizens of major urban environments. Human hair may be an invaluable specimen to determine chronic exposure to any environmental contaminant in an individual, especially in the young population. However, different factors including a lack of studies that have established reference values for metals and metalloids (trace elements) in human scalp hair make the use of this matrix controversial. A monitoring study was performed to establish possible normal or tentative reference values of Al, As, Be, Cd, Cr, Cu, Hg, Mn, Pb, Sn, Ti, Tl and Zn in adolescents’ (aged 13–16) hair who have lived since birth in Alcalá de Henares, Madrid region (Spain). Strict inclusion criteria were followed to study the effect of sex on the hair metal content, and the levels of the above contaminants were also studied in park topsoils from Alcalá de Henares. Scalp hair samples were collected from 96 healthy adolescents (28 boys and 68 girls), and reference values were calculated following the recommendations of the International Union of Pure and Applied Chemistry. The levels of Cd, Cu, Pb, Sn and Zn in hair of adolescents from Alcalá de Henares show a sex dependency, being significantly higher in female participants. Sex should be a factor taken into account when developing future reference values and hair metal content. Soil metal contamination was not correlated with the levels found in hair. To conclude, the values of metals and metalloids here analysed and discussed could be considered as tentative reference values for Spanish adolescents aged 13–16 years living in the Madrid region, and may be used to identify the level of exposure of adolescents in this Spanish region to the various metals and metalloids.

     

An expanded conceptual framework for solution-focused management of chemical pollution in European waters

Background

This paper describes a conceptual framework for solutions-focused management of chemical contaminants built on novel and systematic approaches for identifying, quantifying and reducing risks of these substances.

Methods

The conceptual framework was developed in interaction with stakeholders representing relevant authorities and organisations responsible for managing environmental quality of water bodies. Stakeholder needs were compiled via a survey and dialogue. The content of the conceptual framework was thereafter developed with inputs from relevant scientific disciplines.

Results

The conceptual framework consists of four access points: Chemicals, Environment, Abatement and Society, representing different aspects and approaches to engaging in the issue of chemical contamination of surface waters. It widens the scope for assessment and management of chemicals in comparison to a traditional (mostly) perchemical risk assessment approaches by including abatement- and societal approaches as optional solutions. The solution-focused approach implies an identification of abatement- and policy options upfront in the risk assessment process. The conceptual framework was designed for use in current and future chemical pollution assessments for the aquatic environment, including the specific challenges encountered in prioritising individual chemicals and mixtures, and is applicable for the development of approaches for safe chemical management in a broader sense. The four access points of the conceptual framework are interlinked by four key topics representing the main scientific challenges that need to be addressed, i.e.: identifying and prioritising hazardous chemicals at different scales; selecting relevant and efficient abatement options; providing regulatory support for chemicals management; predicting and prioritising future chemical risks. The conceptual framework aligns current challenges in the safe production and use of chemicals. The current state of knowledge and implementation of these challenges is described.

Conclusions

The use of the conceptual framework, and addressing the challenges, is intended to support: (1) forwarding sustainable use of chemicals, (2) identification of pollutants of priority concern for cost-effective management, (3) the selection of optimal abatement options and (4) the development and use of optimised legal and policy instruments.

     

Modeling road building,deforestation and carbon emissions due deforestation in the Ecuadorian Amazon: the potential impact of oil frontier growth

In the Ecuadorian Amazon roads play the major role in transforming land cover. Since the beginning of the oil development in this region, oil exploration and road building have been linked. The objectives of this paper are twofold: First, to present a scenario of future deforestation as result of expanding the oil frontier in the Ecuadorian Amazon until the year 2030. Second, to produce an analysis of possible carbon emission scenarios as results of the deforestation produced. This paper tries to shed light into how the development of new oil concessions impact land associated environmental services. The paper uses spatial explicit simulations, that are based on parameters built using past land transitions from areas that experimented oil development, and that explain possible outcomes in the year 2030 using current and predicted road network. Simulations indicate that under current transition probabilities and a conservative scenario road construction, more than 2 million hectares will be affected, which is 35% of the area covered by concessions, which would release 51 to 148 MT of carbon to the atmosphere. This paper illustrates the strong links between road building and deforestation, where even small amount of road construction can have large effects on land cover.