Liver alterations in Oreochromis niloticus (Pisces) induced by insecticide imidacloprid: Histopathology and heat shock protein in situ localization

Liver is very sensitive to environmental contaminants such as pesticides, it being the first target of toxicity of a substance. The objective of this study was to investigate the possible effects of the insecticide imidacloprid (IMI) on the liver of Oreochromis niloticus according concentrations used for growing sugarcane. A semi-quantitative analysis of histopathological alterations of IMI on liver was performed by light microscopy and cellular labeling of heat shock proteins (HSP70) by immunohistochemistry. The most common changes in liver at all concentrations of IMI were hydropic degeneration, pyknotic nuclei, and loss of cell limits. Steatosis and increased levels of HSP70 were detected in hepatocytes with the highest concentration of IMI. In conclusion, the tested concentrations of IMI induced histopathological changes in the liver of O. niloticus and active defence mechanisms to maintain the morphophysiological integrity of the liver. This insecticide has a toxicity potential for these fish, which is a non-target organism of its action.     

Reduced light avoidance in spiders from populations in light-polluted urban environments

New finds of bones of the Egyptian Mongoose (Herpestes ichneumon), one from Portugal and one from Spain, were directly ¹⁴C dated to the first century AD. While the Portuguese specimen was found without connection to the Chalcolithic occupation of the Pedra Furada cave where it was recovered, the Spanish find, collected in the city of Mérida, comes from a ritual pit that also contained three human and 40 dog burials. The finds reported here show that the Egyptian mongoose, contrary to the traditional and predominant view, did not first arrive in the Iberian Peninsula during the Muslim occupation of Iberia. Instead, our findings are consistent with the hypothesis that the species was first introduced by the Romans, or at least sometime during the Roman occupation of Hispania. Therefore, radiocarbon dating of new archaeological finds of bones of the Egyptian Mongoose (Herpestes ichneumon) in the Iberian Peninsula push back the confirmed presence of the species in the region by approximately eight centuries, as the previously oldest dated record is from the ninth century. With these new dates, there are now a total of four ¹⁴C dated specimens of Egyptian mongooses from the Iberian Peninsula, and all of these dates fall within the last 2000 years. This offers support for the hypothesis that the presence of the species in Iberia is due to historical introductions and is at odds with a scenario of natural sweepstake dispersal across the Straits of Gibraltar in the Late Pleistocene (126,000–11,700 years ago), recently proposed based on genetic data.

     

Fate and degradation of triasulfuron in soil and water under laboratory conditions

The behavior and fate of triasulfuron (TRS) in water and soil systems were examined in laboratory studies. The degradation of TRS in both buffer solution and soil was highly pH-sensitive. The rate of degradation could be described with a pseudo first-order kinetic and was much faster at pH 4 than at pH 7 and 9. Aqueous hydrolysis occurred by cleavage of the sulfonylurea bridge to form 2-(2-chloroethoxy) benzenesulfonamide (CBSA) and [(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] (AMMT). AMMT was unstable in aqueous solutions in any pH condition but it degraded more quickly at pH 4 and 9. CBSA did not degrade in aqueous solutions or in enriched cultures but it underwent a quick degradation in the soil. The rates of TRS degradation in sterile and non-sterile soils were similar, suggesting that microorganisms played a minimal role in the breakdown process. This hypothesis is supported by the results of studies on the degradation of TRS by enriched cultures during which the molecule underwent a prevalently chemical degradation.     

Environmental monitoring of water resources around a municipal landfill of the Rio Grande do Sul state,Brazil

Environmental Science and Pollution Research - In Brazil, landfills are commonly used as a method for the final disposal of waste that is compliant with the legislation. This technique, however,...     

Germination of Medicago sativa is inhibited by soluble compounds in cement dust

Deposition of cement dust on soils and plant surfaces is known to affect plant growth and the species composition of plant communities, but little is known about its effects (and those of its pH and constituents) on germination. Therefore, the aim of this study was to assess the toxicity of an aqueous cement extract, constituents of the extract and pH on the germination of seeds of a selected species, Medicago sativa. First, the effects of the extract were tested in assays with concentrations and exposure durations ranging from 0 to 1.0 g/mL and 4 to 96 h, respectively. At 0.8 g/mL, the extract strongly inhibited germination; a 4-h exposure reduced the germination rate, from 77?±?1.8 to 50?±?2.6 % (mean ± SE), while 8-h exposure completely inhibited it. Further, treatment at this concentration killed the non-germinating seeds, thus the inhibition was due to toxic effects. Neither the pH of the extract nor the concentration of its main soluble elements separately (K, Ca, S, Na, or Cr) caused the toxicity since germination rates were not significantly reduced when these variables were tested individually. However, a mixture of the elements in solution reduced germination rates, suggesting that they have adverse synergistic effects.     

The determinants of support levels for wind energy in the European Union. An econometric study

The aim of this paper is to identify the factors that drive support levels for wind on-shore electricity in the Member States of the European Union (EU) with the help of econometric techniques. The econometric analysis is based on cross-section linear regressions with ordinary least squares. Four alternative specifications of the model have been estimated. The estimates comply with the basic hypotheses of the lineal model, i.e., absence of multicollinearity, accurate functional form, homokedasticity and normality in the distribution of errors. Thus, the estimations are unbiased, efficient and consistent. The results show that countries with higher wind energy generation costs have higher support levels. The higher support levels in countries with higher carbon intensities suggest that wind energy deployment is regarded as effective to mitigate carbon emissions. The type of support scheme also influences support levels, with feed-in tariffs leading to lower levels of support than other instruments. In addition, a general good investment climate in the country makes higher support levels less necessary, stressing the importance of lowering risks in order to reduce support levels and, thus, financial transfers from consumers to producers. Thus, providing stable regulatory frameworks should be a priority of policy-makers. The rest of variables (renewable energy resource potentials, administrative barriers, energy import dependency, interest rates, share of wind energy in total electricity generation as a proxy of lobbying pressures and electricity demand) are not statistically significant in most specifications and some of them do not have the expected sign.     

Microbial and kinetic characterization of pure and mixed cultures aerobically degrading 4-nitrophenol

The molecular and kinetic characterization of a microorganism able to aerobically degrade 4-nitrophenol (4NP) is presented. The microorganism was isolated from a mixed culture operating in a laboratory-scale sequencing batch reactor with an aerobic anoxic cycle. It was identified as a member of Ralstonia genus within Betaproteobacteria. It is a gram negative coccobacillum (cell length of 2-3 microm) able to aerobically store lipid inclusions when grown aerobically on nitrophenol as the sole carbon source in the range of tested concentrations (80-320 mg l(-1)). Batch kinetic tests were performed with the pure culture, while the kinetics of the mixed biomass was directly investigated in the reactor. For pure cultures exponential growth was observed, with growth rate values in the range of 2-6 d(-1); in experiments with the mixed cultures 4NP concentrations were correlated with growth using the Haldane equation (k(max) = 0.30 mg 4NP mg(-1) VSSh(-1); K(s) = 55 mg 4NPl(-1) and K(I) = 15 mg 4NPl(-1)). Observed pure culture growth rates were higher than those of mixed cultures. This result can be explained by considering that in mixed culture the biomass is evaluated as volatile suspended solids, including both specialized biomass for 4NP removal and denitrifying bacteria.     

Remediation efficiency of vapour extraction of sandy soils contaminated with cyclohexane: Influence of air flow rate, water and natural organic matter content

This work reports the analysis of the efficiency and time of soil remediation using vapour extraction as well as provides comparison of results using both, prepared and real soils. The main objectives were: (i) to analyse the efficiency and time of remediation according to the water and natural organic matter content of the soil; and (ii) to assess if a previous study, performed using prepared soils, could help to preview the process viability in real conditions. For sandy soils with negligible clay content, artificially contaminated with cyclohexane before vapour extraction, it was concluded that (i) the increase of soil water content and mainly of natural organic matter content influenced negatively the remediation process, making it less efficient, more time consuming, and consequently more expensive; and (ii) a previous study using prepared soils of similar characteristics has proven helpful for previewing the process viability in real conditions.