Electrochemical removal of synthetic textile dyes from aqueous solutions using Ti/Pt anode: role of dye structure

In this work, the efficiency of electrochemical oxidation (EO) was investigated for removing a dye mixture containing Novacron Yellow (NY) and Remazol Red (RR) in aqueous solutions using platinum supported on titanium (Ti/Pt) as anode. Different current densities (20, 40 and 60 mA cm^?2) and temperatures (25, 40 and 60 °C) were studied during electrochemical treatment. After that, the EO of each of these dyes was separately investigated. The EO of each of these dyes was performed, varying only the current density and keeping the same temperature (25 °C). The elimination of colour was monitored by UV-visible spectroscopy, and the degradation of organic compounds was analysed by means of chemical oxygen demand (COD). Data obtained from the analysis of the dye mixture showed that the EO process was effective in colour removal, in which more than 90 % was removed. In the case of COD removal, the application of a current density greater than 40 mA cm^?2 favoured the oxygen evolution reaction, and no complete oxidation was achieved. Regarding the analysis of individual anodic oxidation dyes, it was appreciated that the data for the NY were very close to the results obtained for the oxidation of the dye mixture while the RR dye achieved higher colour removal but lower COD elimination. These results suggest that the oxidation efficiency is dependent on the nature of the organic molecule, and it was confirmed by the intermediates identified. Figure

Chemical structures of a NY and b RR     

Phragmites sp. physiological changes in a constructed wetland treating an effluent contaminated with a diazo dye (DR81)

The role of Phragmites sp. in phytoremediation of wastewaters containing azo dyes is still, in many ways, at its initial stage of investigation. This plant response to the long-term exposure to a highly conjugated di-azo dye (Direct Red 81, DR81) was assessed using a vertical flow constructed wetland, at pilot scale. A reed bed fed with water was used as control. Changes in photosynthetic pigment content in response to the plant contact with synthetic DR81 effluent highlight Phragmites plasticity. Phragmites leaf enzymatic system responded rapidly to the stress imposed; in general, within 1 day, the up-regulation of foliar reactive oxygen species-scavenging enzymes (especially superoxide dismutase, ascorbate peroxidase (APX), glutathione peroxidase (GPX) and peroxidase) was noticed as plants entered in contact with synthetic DR81 effluent. This prompt activation decreased the endogenous levels of H₂O₂ and the malonyldialdehyde content beyond reference values. Glutathione S-transferase (GST) activity intensification was not enough to cope with stress imposed by DR81. GPX activity was pivotal for the detoxification pathways after a 24-h exposure. Carotenoid pool was depleted during this shock. After the imposed DR81 stress, plants were harvested. In the next vegetative cycle, Phragmites had already recovered from the chemical stress. Principal component analysis (PCA) highlights the role of GPX, GST, APX, and carotenoids along catalase (CAT) in the detoxification process.     

Method of median semi-variance for the analysis of left-censored data: Comparison with other techniques using environmental data

In environmental monitoring, variables with analytically non-detected values are commonly encountered. For the statistical evaluation of these data, most of the methods that produce a less biased performance require specific computer programs. In this paper, a statistical method based on the median semi-variance (SemiV) is proposed to estimate the position and spread statistics in a dataset with single left-censoring. The performances of the SemiV method and 12 other statistical methods are evaluated using real and complete datasets. The performances of all the methods are influenced by the percentage of censored data. In general, the simple substitution and deletion methods showed biased performance, with exceptions for L/2, Inter and L/√2 methods that can be used with caution under specific conditions. In general, the SemiV method and other parametric methods showed similar performances and were less biased than other methods. The SemiV method is a simple and accurate procedure that can be used in the analysis of datasets with less than 50% of left-censored data.     

Of Catholicism,Forest and Management: An Analysis of Imaginaries in the Discussion of the Native Forest Law in Chile

The relationship between media and the construction of environmental policy has been studied acutely in the Global North. However, less attention has been paid to deeper cultural symbols displayed in public policy discussions in the Global South. Through qualitative examination of 100 letters to the editor (LTE) of the Chilean newspaper, El Mercurio, this study examined the imaginaries in the public discussion of the Native Forest Policy in Chile. Although such a discussion was often framed as a technical debate, the letters to El Mercurio were embedded within Catholic imaginaries, condensed into two main sets. The first one constructed forests as endangered due to human action and called for immediate protection, contending that humans shall not destroy God's creation. The second set depicted a degraded forest in need of rational management to satisfy the needs of God's children. This study suggests that, in a mediated public discussion, religion might play an important role in communicating environmental issues. This work contributes to our understanding of environmental imaginaries and discourses in the context of environmental controversies, to the understanding of the functions of the LTE, and to the social construction of forest policy in recent post-autocratic regimes.     

Potentiation of antifungal effect of a mixture of two antifungal fractions obtained from Baccharis glutinosa and Jacquinia macrocarpa plants

The aim of the present work was to evaluate the effect of mixtures of antifungal fractions extracted from Baccharis glutinosa and Jacquinia macrocarpa plants on the development of the filamentous fungi Aspergillus flavus and Fusarium verticillioides. The minimal inhibitory concentration that inhibited 50% of growth (MIC₅₀) of each plant antifungal fraction was determined from the percentage radial growth inhibition of both fungi. Binomial mixtures made with both plant fractions were used at their MIC₅₀ to determine the Fractional Inhibitory Concentration index (FIC index) for each fungus in order to evaluate their synergistic effect. Each synergistic mixture was analyzed in their effect on spore germination, spore size, spore viability, mitotic divisions, hyphal diameter and length, and number of septa per hypha. Some antifungal mixtures, even at low concentrations, showed higher antifungal effect than those of the individual antifungal fraction. The FIC indices of mixtures that showed the highest antifungal activity against A. flavus and F. verticillioides were 0.5272 and 0.4577, respectively, indicating a synergistic effect against both fungi. Only 12% and 8% of the spores of A. flavus and F. verticillioides, respectively, treated with the synergistic mixtures, were able to germinate, although their viability was not affected. An increase in the number of septa per hypha of both fungi was observed. The results indicated that the synergistic mixtures strongly affected the fungal growth even at lower concentrations than those of the individual plant fractions.     

Mortality of the scleractinian coral <Emphasis Type="Italic">Cladocora caespitosa</Emphasis> during a warming event in the Levantine Sea (Cyprus)

A mortality event of Cladocora caespitosa corals and the extent of bleaching, necrosis and pigmented areas in the colonies were studied at the southeastern coast of Cyprus during a prolonged period of higher than average sea temperature anomalies (summer/autumn 2012). With the use of scuba diving and image analysis software, we monitored the extent of mortality of 29 colonies of C. caespitosa by measuring and comparing the area percentage of healthy tissue, affected tissue (bleached, necrotic) and older mortality events (encrusted skeleton). In September 2012, on average, 24 % of the colonies surface area was affected (bleaching and/or necrosis). In October 2012, C. caespitosa showed on average 26.3 % of the colony surface area affected, evidence of continuing deterioration. At the same time, 10 % (3 of 29) of the colonies showed an increase in the pigmentation of previously bleached polyps in small and marginal areas (6–8 %). Irrespective of the amount, the regaining of pigments recorded is considered an important find. Corals and marine organisms in general in the Levantine Sea are affected greatly by warming events, to the extent where a very small percentage of polyps/colonies show resilience under thermal stress. Natural bleaching of C. caespitosa, even though limited to a few colonies and very small portions of tissue/polyps, was documented for the first time in the Levantine Sea. We conclude that temperature anomalies are associated with the mortality event. Whether prolonged higher temperature is the direct cause, or whether it acts synergistically with other factors should be the subject of further investigations.     

Consumer willingness to pay for organic and locally grown produce on Dominica: insights into the potential for an “Organic Island”

With the intent of improving agricultural revenues and solidifying her place as an ecotourism destination, it has been proposed that the island nation of The Commonwealth of Dominica convert all agriculture to organic production. This study explores Dominica’s current and potential domestic demand for organic and/or “locally grown” produce. Surveys were conducted with Dominican consumers to assess their opinions and willingness to pay for these products, and evaluated using a maximum likelihood estimation procedure. On average, Dominican consumers are willing to pay 17.5 % more for organic, and 12 % more for locally grown, produce. These results were varied significantly across demographic segments of the sampled population, respondent tastes and preferences, the health status of their family, and the extent to which they were early adopters of new products. Despite several expected challenges of a successful transition to organic, implementation of this policy may offer a net positive welfare increase for Dominica’s permanent residents. Results from this analysis suggest that, from the perspective of domestic consumers, Dominica should continue to pursue the possibility of becoming an “Organic Island.”     

Influence of different abiotic and biotic factors on the metalaxyl and carbofuran dissipation

Metalaxyl and carbofuran dissipation was studied in response to different factors (soil bacterial communities, light irradiation, presence of an inorganic culture medium and presence of soil) and combinations of these factors in short-term experiments (48 h). The soil microbial communities have no effect on metalaxyl or carbofuran dissipation in the time scale employed. Light irradiation and soil promote metalaxyl and carbofuran dissipation by photodegradation and adsorption, respectively. However, photodegradation has a stronger effect on metalaxyl and carbofuran dissipation than the adsorption of the pesticides in the soil. The addition of the culture medium have no direct effect on pesticide dissipation, degradation by microbial communities or adsorption but its presence greatly increased photodegradation.     

Catalytic ozonation of 2,4-Dichlorophenoxyacetic acid using alumina in the presence of a radical scavenger

Using a laboratory-scale mixed reactor, the performance of alumina in degrading 2,4-Dichlorophenoxyacetic acid with ozone in the presence of tert-butyl alcohol radical scavenger was studied. The operating variables investigated were the dose of alumina catalyst and solution pH. Results showed that using ozone and alumina leads to a significant increase in 2,4-D removal in comparison to non-catalytic ozonation and adsorption processes. The observed reaction rate constants (k_obs ) for 2,4-D during ozonation were found to increase linearly with increasing catalyst dose. At pH 5, the k_obs value increased from 19.3 to 26 M^?1 s^?1 and 67 M^?1 s^?1 when varying the alumina dose from 1 to 2 and 4 g L^?1, respectively. As pH was increased, higher reaction rates were observed for both non-catalytic ozonation and catalytic ozonation processes. Thus, at pH 3 and using a catalyst dose of 8 g L^?1, the k_obs values for non-catalytic ozonation and catalytic ozonation processes were 3.4 and 58.9 M^?1 s^?1, respectively, whereas at pH 5 reaction rate constants of 6.5 and 128.5 M^?1 s^?1 were observed, respectively. Analysis of total organic carbon suggested that catalytic ozonation with alumina achieved a considerable level of mineralization of 2,4-D. Adsorption of 2,4-D on alumina was found to play an important role in the catalytic ozonation process.