Insights into PU/EVA Blends Produced Using Industrial Residues Towards Eco-efficient Materials

Journal of Polymers and the Environment - Aiming at minimizing the issues associated with the disposal of polymers, in this study, elastomeric materials derived from 100% recycled feedstocks were...     

Optical fiber based methodology for assessment of thiocyanate in seawater

A new methodology for the assessment of thiocyanate (SCN(-)) is proposed based on optical fiber (OF) detection coupled to a liquid chromatography system (LC). The developed methodology showed an adequate performance for the analysis of SCN(-) comparable to a high performance liquid chromatography with UV detector (HPLC-UV) methodology: a detection limit of 3 μg L(-1), a linear range from 4 to 400 μg L(-1), and an analytical time of less than 6 min. The OF based methodology was of compact design and easy operation. This simple system has the potential to be used as a sensing approach for SCN(-) in seawater.     

Accumulation of metals in the soil of an overland flow wastewater treatment system

Accumulation of Co, Cu, Cr, Mo, Ni, Pb and Zn was evaluated in a soil profile of an overland flow system used for the post-treatment of urban wastewater. A pilot version of the overland flow system received urban wastewater from five up-flow anaerobic filters filled with bamboo (Bambusa tuldoides) rings. The anaerobic effluent was applied as feed over 18 months at rates varying from 7 to 28 L min(-1), to a vegetated slope length covered with Tifton 85 (Cynodon) sp. grass. Soil and plant samples were collected in triplicate from the top to the bottom of the slope. In addition, the soils were sampled at the depths 0-20 and 20-40 cm. The metal concentrations found in the overall system were compared to those obtained in a control area located at the beginning of the slope onto which nothing was applied. A month of monitoring the urban wastewater of Limeira City (S?o Paulo State, Brazil) showed a drastic change in metals concentration due to the irregular discharge of industrial waste. This irregular discharge introduces Cr, Cu, Ni, Pb and Zn into the system used to treat domestic wastewater. The mass balance indicates the accumulation of metals in the soil and the translocation to the plants; also that they could be evapotranspirated, percolated and discharged.     

Contribution of Spartina maritima to the reduction of eutrophication in estuarine systems

Salt marshes are among the most productive ecosystems in the world, performing important ecosystem functions, particularly nutrient recycling. In this study, a comparison is made between Mondego and Tagus estuaries in relation to the role of Spartina maritima in nitrogen retention capacity and cycling. Two mono-specific S. maritima stands per estuary were studied during 1 yr (biomass, nitrogen (N) pools, litter production, decomposition rates). Results showed that the oldest Tagus salt marsh population presented higher annual belowground biomass and N productions, and a slower decomposition rate for litter, contributing to the higher N accumulation in the sediment, whereas S. maritima younger marshes had higher aboveground biomass production. Detritus moved by tides represented a huge amount of aboveground production, probably significant when considering the N balance of these salt marshes. Results reinforce the functions of salt marshes as contributing to a reduction of eutrophication in transitional waters, namely through sedimentation processes.     

Ants can sort their brood without a gaseous template

A fundamental issue of collective intelligence is whether the collective pattern or process is based on environmental information that explicitly codes for it or arises through self-organization of the individuals. Sometimes, these alternatives occur together. Adaptive systems may also be capable of utilizing different types of mechanism under different conditions. Sendova-Franks et al. (Anim Behav 68:1095–1106, 2004) demonstrated evidence for a self-organization mechanism of brood sorting in the ant Temnothorax albipennis, where the brood are sorted in a series of bands or concentric annuli that increase in size with distance from the colony centre. The work by Cox and Blanchard (J Theor Biol 204:223-238, 2000) suggests an alternative or complementary mechanism whereby the brood pattern is specified by the template of a CO₂ gradient. Here, we test for a gaseous template as a necessary condition for brood sorting. Under the experimental condition, we pumped the air out of the nest continuously to prevent the accumulation of any gaseous substances. We compared the brood pattern between the experimental and control conditions according to four characteristics: mean distance from centre, mean nearest-neighbour distance, shape and area. Under the experimental condition, the order of brood types according to the first two characteristics was the same as in the control. The area of the brood pattern was smaller, and its shape elongated under the experimental condition. As expected on the basis of these differences, mean distance from centre was greater and mean nearest-neighbour distance was smaller under the experimental condition (although not statistically significantly) and by the expected amount. We found evidence that ants avoid placing brood in the strongest airflow stream. This could explain the reduced area and elongated shape of the brood pattern under the experimental condition. We conclude that a gaseous template is not a necessary condition for brood sorting. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Biochemical biomarkers in Nile tilapia (Oreochromis niloticus) after short-term exposure to diesel oil, pure biodiesel and biodiesel blends

Fossil fuels such as diesel are being gradually replaced by biodiesel, a renewable energy source, cheaper and less polluting. However, little is known about the toxic effects of this new energy source on aquatic organisms. Thus, we evaluated biochemical biomarkers related to oxidative stress in Nile tilapia (Oreochromis niloticus) after two and seven exposure days to diesel and pure biodiesel (B100) and blends B5 and B20 at concentrations of 0.01 and 0.1 mL L⁻¹. The hepatic ethoxyresorufin-O-deethylase activity was highly induced in all groups, except for those animals exposed to B100. There was an increase in lipid peroxidation in liver and gills in the group exposed to the higher concentration of B5. All treatments caused a significant increase in the levels of 1-hydroxypyrene excreted in the bile after 2 and 7 d, except for those fish exposed to B100. The hepatic glutathione-S-transferase increased after 7 d in animals exposed to the higher concentration of diesel and in the gill of fish exposed to the higher concentration of pure diesel and B5, but decreased for the two tested concentrations of B100. Superoxide dismutase, catalase and glutathione peroxidase also presented significant changes according to the treatments for all groups, including B100. Biodiesel B20 in the conditions tested had fewer adverse effects than diesel and B5 for the Nile tilapia, and can be suggested as a less harmful fuel in substitution to diesel. However, even B100 could activate biochemical responses in fish, at the experimental conditions tested, indicating that this fuel can also represent a risk to the aquatic biota.     

EFFECTS OF WATERSHED REPRESENTATION ON RUNOFF AND SEDIMENT YIELD MODELING1

ABSTRACT: This paper evaluates the effects of watershed geometric representation (i.e., plane and channel representation) on runoff and sediment yield simulations in a semiarid rangeland watershed. A process based, spatially distributed runoff erosion model (KINEROS2) was used to explore four spatial representations of a 4.4 ha experimental watershed. The most complex representation included all 96 channel elements identifiable in the field. The least complex representation contained only five channel elements. It was concluded that oversimplified watershed representations greatly influence runoff and sediment yield simulations by inducing excessive infiltration on hillslopes and distorting runoff patterns and sediment fluxes. Runoff and sediment yield decrease systematically with decreasing complexity in watershed representation. However, less complex representations had less impact on runoff and sediment‐yield simulations for small rainfall events. This study concludes that the selection of the appropriate level of watershed representation can have important theoretical and practical implications on runoff and sediment yield modeling in semiarid environments.     

Evaluation of Saccharomyces cerevisiae strains as probiotic agent with aflatoxin B1 adsorption ability for use in poultry feedstuffs

In this study the aflatoxin B₁ (AFB₁) removal capacity, the tolerance to salivary and gastrointestinal conditions, autoaggregation and coaggregation with pathogenic bacteria of Saccharomyces cerevisiae strains isolated from broiler feces, were evaluated. Only four of twelve isolated strains were identified as Saccharomyces cerevisiae using molecular techniques. The results obtained in AFB₁ binding studies indicated that the amount of AFB₁ removed was both strain and mycotoxin-concentration dependent. Therefore, a theoretical model was applied in order to select the most efficient strain to remove AFB₁ in a wide range of mycotoxin concentration. The results indicated that S. cerevisiae 08 and S. cerevisiae 01 strains were the most efficient microorganisms in the mycotoxin removal. Viability on simulated salivary and gastrointestinal conditions was investigated and S. cerevisiae 08 strain showed the best results, achieving 98% of total survival whereas S. cerevisiae 01 reached only 75%. Autoaggregation and coaggregation assays showed S. cerevisiae 08 as the most appropriate strain, mainly because it was the unique strain able to coaggregate with the four bacterial pathogens assayed. Consequently, S. cerevisiae 08 is the best candidate for future in vivo studies useful to prevent aflatoxicosis. Further quantitative in vitro and in vivo studies are required to evaluate the real impact of yeast-binding activity on the bioavailability of AFB₁ in poultry. However, this study could be useful in selecting efficient strains in terms of AFB₁ binding and provide an important contribution to research into microorganisms with potential probiotic effects on the host.     

Copper binding by peat fulvic and humic acids extracted from two horizons of an ombrotrophic peat bog

We studied the binding of Cu(II) to humic acids and fulvic acids extracted from two horizons of an ombrotrophic peat bog by metal titration experiments at pH 4.5, 5.0, 5.5, and 6.0 and 0.1 M KNO3 ionic strength. Free metal ion concentrations in solution were measured using an ion selective electrode. The amounts of base required to maintain constant pH conditions were recorded and used to calculate H+/Cu2+ exchange ratios. The amount of Cu(II) bound to the humic fractions was greater than the amount bound to the fulvic fractions and only at the highest concentrations of metal ion the amount of Cu(II) sorbed by both fractions became equal. The proton to metal ion exchange ratios are similar for all humic substances, with values ranging from 1.0 to 2.0, and decreasing with increased pH. The amount of Cu(II) bound is practically independent of the horizon from which the sample was extracted. The results indicate that the humic substances show similar cation binding behaviour, despite the differences in chemical composition. The copper binding data are quantitatively described with the NICA-Donnan model, which allows to characterize only the carboxylic type binding sites. The values of the binding constants are higher for the humic acids than for the fulvic acids.