Polymer nanoparticles containing essential oils: new options for mosquito control

Environmental Science and Pollution Research - Mosquitoes (Diptera: Culicidae) are vectors of important parasites and pathogens causing death, poverty and social disability worldwide. The overuse...     

Application of Fenton, photo-Fenton, solar photo-Fenton, and UV/H2O2 to degradation of the antineoplastic agent mitoxantrone and toxicological evaluation

In the present study, selected advanced oxidation processes (AOPs)—namely, photo-Fenton (with Fe²⁺, Fe³⁺, and potassium ferrioxalate—FeOx—as iron sources), solar photo-Fenton, Fenton, and UV/H₂O₂—were investigated for degradation of the antineoplastic drug mitoxantrone (MTX), frequently used to treat metastatic breast cancer, skin cancer, and acute leukemia. The results showed that photo-Fenton processes employing Fe(III) and FeOx and the UV/H₂O₂ process were most efficient for mineralizing MTX, with 77, 82, and 90 % of total organic carbon removal, respectively. MTX probably forms a complex with Fe(III), as demonstrated by voltammetric and spectrophotometric measurements. Spectrophotometric titrations suggested that the complex has a 2:1 Fe³⁺:MTX stoichiometric ratio and a complexation constant (K) of 1.47 × 10⁴ M^–1, indicating high MTX affinity for Fe³⁺. Complexation partially inhibits the involvement of iron ions and hence the degradation of MTX during photo-Fenton. The UV/H₂O₂ process is usually slower than the photo-Fenton process, but, in this study, the UV/H₂O₂ process proved to be more efficient due to complexing of MTX with Fe(III). The drug exhibited no cytotoxicity against NIH/3T3 mouse embryonic fibroblast cells when oxidized by UV/H₂O₂ or by UV/H₂O₂/FeOx at the concentrations tested.     

Production and partial characterization of bioemulsifier from a chromium-resistant actinobacteria

Surface-active compounds such as synthetic emulsifiers have been used for several decades, both for the degradation of hydrocarbons and increasing desorption of soil-bound metals. However, due to their high toxicity, low degradability, and production costs unaffordable for use in larger ecosystems, synthetic emulsifiers have been gradually replaced by those derived from natural sources such as plants or microbes. In previous studies, the bacterium Streptomyces sp. MC1 has shown the ability to reduce and/or accumulate Cr(VI), a highly promising advance in the development of methods for environmental clean-up of sites contaminated with chromium. Here, new studies on the production of emulsifier from this strain are presented. The cultivation factors that have a significant influence on emulsifier biosynthesis, as well as the interactions among them, were studied by factorial design. Based upon optimization studies, maximum bioemulsifier production was detected in the culture medium having an initial pH of 8 with phosphate 2.0 g L^?1 and Ca⁺² 1.0 g L^?1 added, with an emulsification index about 3.5 times greater compared to the basal value. Interestingly, in the presence of 5.0 g L^?1 Cr(VI), Streptomyces sp. MC1 retained about 65% of its emulsifier production ability. Partially purified emulsifier presented high thermo-stability and partial water solubility. These findings could have promising future prospects for the remediation of organic- and metal-contaminated sites.     

Evaluation of surface water quality using an ecotoxicological approach: a case study of the Alqueva Reservoir (Portugal)

Background, aim, and scope  

Freshwater reservoirs can be impacted by several hazardous substances through inputs from agricultural activity, sewage discharges, and groundwater leaching and runoff. The water quality assessment is very important for implementation of the monitoring and remediation programs to minimize the risk promoted by hazardous substances in aquatic ecosystems. Evaluation of the degree of contamination of aquatic environments must not take in account only its chemical characterization but it must be complemented with biological assays, which determine potential toxic effects and allows an integrated evaluation of its effects in populations and aquatic ecosystem communities. The application of this type of strategy has clear advantages allowing a general evaluation of the effects from all the water components, including those due to unknown substances and synergic, antagonistic, or additive effects. There are only a few studies that reported ecotoxicological acute end points, for the assessment of surface water quality, and the relationship among toxicity results and the anthropogenic pollution sources and the seasonal period. The aim of this study was to assess the ecotoxicological characterization of the surface water from Alqueva reservoir (South of Portugal) and to evaluate the influence of anthropogenic sources of pollution and their seasonal variation in its toxicity. The construction of Alqueva reservoir was recently finished (2002) and, to our knowledge, an ecotoxicological assessment of its surface water has not been performed. Because of that, no information is available on the possible impact of pollutants on the biota. The surface water toxicity was assessed using acute and chronic bioassays. The results are to be used for developing a monitoring program, including biological methods.     

Gas phase reactions of unsaturated esters with Cl atoms

Background, aim, and scope  

Acrylate and methacrylate esters are α,β-unsaturated esters that contain vinyl groups directly attached to the carbonyl carbon (CH₂=CHCOO– and CH₂=CCH₃COO–, respectively) and are widely used in the polymer plastic and resin production. Rate coefficients for Cl reactions for most of the unsaturated esters have not been previously determined, and a good understanding is needed of all the atmospheric oxidation processes of these compounds in order to determine lifetimes in the atmosphere and to evaluate the impact of these reactions on the formation of photo-oxidants and therefore on health and environment.     

Anaerobic digestion of the liquid fraction of dairy manure in pilot plant for biogas production: residual methane yield of digestate

The performance of the only dairy manure biogas plant in Cantabria (Northern coast of Spain) was evaluated in terms of liquid-solid separation and anaerobic digestion of the liquid fraction. Screened liquid fraction was satisfactorily treated in a CSTR digester at HRTs from 20 to 10 days with organic loading rates ranging from 2.0 to 4.5 kg VS/(m(3)d). Stable biogas productions from 0.66 to 1.47 m(3)/(m(3)d) were achieved. Four anaerobic effluents collected from the digester at different HRTs were analyzed to measure their residual methane potentials, which ranged from 12.7 to 102.4 L/gVS. These methane potentials were highly influenced by the feed quality and HRT of the previous CSTR anaerobic digestion process. Biomethanization of the screened liquid fraction of dairy manure from intensive farming has the potential to provide up to 2% of total electrical power in the region of Cantabria.     

Removal of pharmaceutical compounds from urban wastewater by an advanced bio-oxidation process based on fungi <Emphasis Type="Italic">Trametes versicolor</Emphasis> immobilized in a continuous RBC system

Conventional wastewater treatment plants (WWTPs) are not able to remove completely some emerging contaminants, such as residual pharmaceutical compounds (PCs) with potential ecotoxicity to water bodies. An advanced bio-oxidation process (ABOP) using white-rot fungi (WRF) has been proposed as alternative biological treatment for degradation of non-biodegradable compounds. A synthetic and real wastewater spiked with 12 PCs at 50 μg L^?1 was treated by means of ABOP based on WRF in a rotating biological contactor (RBC) at 1 day of hydraulic retention time (HRT). The ABOP achieved a remarkable biological performance in terms of TOC removal and reduction of N-NH₄ ⁺ and P-PO₄ ^3? nutrients. Likewise, 5 of the 12 PCs were eliminated with removal efficiencies ranging from 80 to 95%, whereas 6 of 12 PCs were eliminated with removal values ranging from 50 to 70%. The anaerobic digestion of the fungal sludge generated upon the treatment was also evaluated, obtaining a methane yield of 250 mL CH₄ g_VS ^?1. These results evidenced that the proposed ABOP is a promising alternative for the sustainable wastewater treatment of urban effluents, combining advanced oxidation with biological operation for the removal of emerging PCs and energy recovery.     

Cultivable microbiome and its resistance to antimicrobials isolated from <Emphasis Type="Italic">Zaprionus indianus</Emphasis>

The objective of this study was to identify Z. indianus in PEJC and PESCAN. Listed are the following methods: to isolate bacteria from the integument of the Z. indianus species collected and to check the resistance of microorganisms to antibiotics. Collections of Z. indianus were performed in four seasons of the two parks. The results obtained suggest that the low amount of Z. indianus collected can be justified by environmental factors such as high average temperature and low average humidity. It is noted that there is a predominance of bacteria of the Enterobacteriaceae family found in both the PEJC and the PESCAN. The antibiogram performed for the isolated PEJC bacteria shows statistical significance when comparing the edge and inside values of the park. Studies with fungi were also carried out, and it was evidenced that Trichophyton spp. was the genus that most inhabited the two environments studied. The ability of fluconazole and ketoconazole to inhibit fungal growth was also investigated, and considering the concentration tested may suggest that they have good action spectra. Plasmid profile data show that 60% of antibiotic-resistant bacteria have plasmids. The values found show that Z. indianus can act as vectors of microorganisms that affect the healthy animals and humans and that these organisms may be influenced by seasons.     

Comparative effect of compost and technosol enhanced with biochar on the fertility of a degraded soil

A large number of studies on the reclamation of mine soils focused on the problem caused by metals and did not explore in depth the issue of nutrients and vegetation after the application of organic materials. The aim of this study was to compare the effect of two treatments made of wastes and vegetated with Brassica juncea L. on the fertility of a settling pond mine soil. The first treatment was compost, biochar, and B. juncea (SCBP) and the second treatment was technosol, biochar, and B. juncea (STBP). This study evaluated the effect of the treatments on the soil nutrient concentrations and fertility conditions in the soil amendment mixtures, after 11 months of greenhouse experiment. Total carbon and nitrogen concentrations were higher in treatment SCBP than in treatment STBP after 7 months but, after 11 months, carbon concentration was higher in STBP. The used technosol could have forms of carbon more stable than compost, which could be released slower than in the compost-amended soils. Both compost and technosol mixed with biochar also increased the concentration of calcium, potassium, magnesium, and sodium in exchangeable form in the mine soil.     

Strategies to optimize monitoring schemes of recreational waters from Salta,Argentina: a multivariate approach

Several recreational surface waters in Salta, Argentina, were selected to assess their quality. Seventy percent of the measurements exceeded at least one of the limits established by international legislation becoming unsuitable for their use. To interpret results of complex data, multivariate techniques were applied. Arenales River, due to the variability observed in the data, was divided in two: upstream and downstream representing low and high pollution sites, respectively, and cluster analysis supported that differentiation. Arenales River downstream and Campo Alegre Reservoir were the most different environments, and Vaqueros and La Caldera rivers were the most similar. Canonical correlation analysis allowed exploration of correlations between physicochemical and microbiological variables except in both parts of Arenales River, and principal component analysis allowed finding relationships among the nine measured variables in all aquatic environments. Variable’s loadings showed that Arenales River downstream was impacted by industrial and domestic activities, Arenales River upstream was affected by agricultural activities, Campo Alegre Reservoir was disturbed by anthropogenic and ecological effects, and La Caldera and Vaqueros rivers were influenced by recreational activities. Discriminant analysis allowed identification of subgroup of variables responsible for seasonal and spatial variations. Enterococcus, dissolved oxygen, conductivity, E. coli, pH, and fecal coliforms are sufficient to spatially describe the quality of the aquatic environments. Regarding seasonal variations, dissolved oxygen, conductivity, fecal coliforms, and pH can be used to describe water quality during dry season, while dissolved oxygen, conductivity, total coliforms, E. coli, and Enterococcus during wet season. Thus, the use of multivariate techniques allowed optimizing monitoring tasks and minimizing costs involved.