Resistance to metal contamination by historically-stressed populations of Ceriodaphnia pulchella: environmental influence versus genetic determination

Field populations of daphnids historically-stressed by metal contamination may show increased resistance to those contaminants. This study was undertaken aiming to confirm/infirm three main hypotheses: (1) field populations living in historically-impacted environments are more tolerant to metal stress than populations from reference sites; (2) resistance differences are genetically-determined, i.e., differences persist after controlling for environmental and maternal effects, by acclimating cloned lineages to similar conditions; and (3) resistance to stress in field populations living in historically-impacted environments is due to the disappearance of sensitive individuals rather than the appearance of highly resistant ones, i.e., the shift in the central tendency of resistance is linked to a decrease in the range of population resistance and not to an increased upper limit of the population resistance. Three populations of the cladoceran Ceriodaphnia pulchella Sars in Southern Portugal were sampled; one of which has been historically-stressed by acid mine drainage (AMD) from an abandoned cupric-pyrite mine and two from reference sites within the same watershed. To assess if resistance differences were genetically-determined, the three populations were acclimated for at least five generations under the same controlled conditions. Assays with AMD contaminated water samples were performed with both non-acclimated and acclimated individuals from all studied populations. Reproduction results in sub-lethal assays revealed significant differences between the reference and stressed populations. Significant differences in resistance to lethal levels of toxicity were observed for both non-acclimated and acclimated populations, individuals from population I being more resistant than those from reference populations. The existence of genetically-determined sensitivity differences was attested by the presence of significant differences in resistance to lethal levels of toxicity in acclimated individuals from reference and stressed populations. Results from cumulative mortality assays revealed that sensitive individuals were most probably present in the original population, but no conclusion could be draw about the presence of extreme resistant individuals in the historically-stressed population. Finally, it was shown that responses among populations converged from high to low levels of contamination.     

Solar photodegradation of dichloroacetic acid and 2,4-dichlorophenol using an enhanced photo-Fenton process

The photo-Fenton process using potassium ferrioxalate as a mediator was investigated for the photodegradation of dichloracetic acid (DCA) and 2,4-dichlorophenol (DCP) in aqueous medium using solar light as source of irradiation. The influence of the solution depth, the light intensity and the effect of stirring the solution during irradiation process were evaluated using DCA as a model compound. A negligible influence of stirring the solution was observed when the concentration of ferrioxalate (FeOx) was 0.8 mM and solution depth was 4.5 or 14 cm. The optimum FeOx concentration determined for solution depths between 4.5 and 14 cm was 0.8 mM considering total organic carbon (TOC) removal during DCA irradiation. The high efficiency of the photo-Fenton process was demonstrated on summer days, when only 10 min of exposition (around noon) were sufficient to completely destroy the organic carbon of a 1.0 mM DCA solution in the presence of 0.8 mM FeOx and 6.0 mM H2O2 using a solution depth of 4.5 cm. It was observed that the photodegradation efficiency increases linearly with the solar light intensity up to values around 15 Wm(-2) but this linear relationship does not hold above this value showing a square root dependence. The photodegradation of a solution of DCP/FeOx showed a lower TOC removal rate than that observed for DCA/FeOx, achieving approximately 90% after 35 min irradiation under 19 W m(-2), while under this light intensity, the same TOC removal of DCA/FeOx was achieved in only 10 min irradiation.     

Laboratory study of effects of temperature and salinity on survival and larval development of a population of Rhithropanopeus harrisii from the Mondego River estuary,Portugal

Rhithropanopeus harrisii (Gould) is an introduced species in the estuary of the Mondego River (Portugal): it was first recorded from the Iberian Peninsula in 1989. The larval development of this population was studied under laboratory conditions at different temperatures and salinities, and showed a larval development pattern very similar to that reported for American estuarine populations of this species. Larval development was negatively correlated with temperature. Time to megalopa varied between 7 and 35 d; the first crab (C₁) was reached after a maximum of 11 to 43 d. Larval development was optimum at 25°C and 15S. Larval survival was maximum at 10, 15 and 20S at all three temperatures studied (20, 25 and 30°C). The percentage of abnormal megalopae increased with increasing salinity to a maximum (100%) at 30S; incidence of abnormality was not affected by temperature.     

Environmental practices of governance of companies in emerging markets: An analysis of structural relationships

The aim of this study is to analyze the structural relationships between strategy, environmental performance, and disclosure in view of the lack of research on these endogenous activities. To analyze these relationships, an environmental governance proxy consisting of five dimensions was developed for Brazilian companies. Hence, from an economic perspective, a trend is expected of companies disclosing more information and maintaining an environmental governance structure to avoid or reduce potential political costs. Using the structural equation technique, 573 Brazilian companies were analyzed. According to the results, the Brazilian companies’ mean compliance level with environmental governance practices is 49.2%. There is evidence of a positive association between the governance structure and the environmental management system (GSEM) as well as environmental performance (EP) and environmental disclosure levels (DISC). In addition, the level of environmental conflicts of interest a sector faces increased the need for environmental disclosure. Furthermore, the results demonstrate that the latent variables, GSEM and EP, exert direct and indirect positive effects on DISC. In other words, companies with more structured environmental management systems have obtained better performance indicators, and consequently, are more likely to feel encouraged to disseminate environmental information and to reduce political costs than is the case with other companies.     

Gastroenteric Viruses Detection in a Drinking Water Distribution-to-Consumption System in a Low-Income Community in Rio de Janeiro

Food and Environmental Virology - The availability of drinking water is one of the main determinants of quality of life, disease prevention and the promotion of health. Viruses are important agents...     

Comparison between EMINENT and other energy technology assessment tools

Currently, issues related with climate change, security of energy supply, energy efficiency and sustainability are at the core of all energy policies and strategies. The current technologies are not able to face this challenge; therefore, the development of new and more sustainable energy technologies must be supported.As part of this, energy technology assessment tools can help decision-makers in the identification and evaluation of sustainable energy solutions, in order to integrate them in long term energy strategies.The EMINENT tool was developed to assess the performance and market potential of early stage technologies (EST) in a pre-defined energy chain, under national conditions, in terms of financial, energy and environmental criteria.This paper presents a comparative study between EMINENT and other tools for energy technology assessment. The tools analysed were CO2DB, MARKAL, IKARUS and E3Database.Although there are many different energy technology assessment tools, EMINENT seems to be the only one targeting EST.     

A Life Cycle Engineering model for technology selection: a case study on plastic injection moulds for low production volumes

The selection of the most appropriated technological solution to produce a certain mould able to competitively produce parts in polymeric materials is a multi-disciplinary activity, which integrates different knowledge fields and professional domains. The selection decision should capture not only the technical performance required for the mould to produce the final part in the expected quantities and intended quality, but also the economic issues and environmental impacts originated all along the mould life cycle. In this paper a Life Cycle Engineering (LCE) model is proposed to support the selection of alternative technological solutions through the integration of these three analysis dimensions underlined by the LCE approach. The model proposed has the novelty of integrating the three dimensions through the use of easy-to-read ternary diagrams allowing the identification of the “best domains” of each technological alternative. With the integrated analysis, the present model fosters the global comparison of alternatives according to different business scenarios and corporate strategies, supporting an informed decision-making process. The model was applied to a case study aiming the production of very small production volumes of polymeric parts. Two candidate technologies were evaluated: one involving a mould made of a spray metal shell backfilled with resin and aluminium powder and another based on the machining of aluminium.