Degradação de poluentes emergentes por processos Fenton e foto-Fenton

A continuous photochemical treatment system was developed for aiming the treatment of aqueous solutions containing relevant micro-pollutants (microcystin-LR, sulfamethoxazole and 17-b estradiol). The continuous photo-Fenton process provided high degradation efficiency. However, contact time between samples and the irradiated region is short relative to total treatment time, indicating that observed changes are predominantly due to the Fenton process. Higher degradation efficiency was observed in systems operated using two treatment cycles, the first involving a batch Fenton process and the second a continuous photo-Fenton treatment.

Determinação de plastificantes em água potável utilizando cromatografia gasosa e espectrometria de massas

This study investigated the levels of plasticizer endocrine disruptors (diethyl phthalate, dibutyl phthalate, and bisphenol A) in drinking water at Paraíba do Sul River region and release of these compounds from bottled water. An analytical method employing solid phase extraction and GC/MS was optimized and validated. The results showed that the method is selective, linear (r² > 0.99), precise (RSD <12%), accurate (recoveries between 62 and 105%), sensitive and robust. Applying the method, the presence of all studied pollutants in drinking water was observed for the three sampled plasticizers. These plasticizers were not found in mineral bottled water, before or after storage.

Oxidação eletroquímica do herbicida tebutiuron utilizando eletrodo do tipo DSA

Tebuthiuron (TBH) is a herbicide widely used in different cultures and known for its toxic effects. Electrochemical methods are promising for removing pollutants such as pesticides. This study showed the degradation of TBH using a DSA® anode operated at current densities of 50 to 200 mA cm-2. Removal presented pseudo-first order kinetics while high-pressure liquid chromatography (UV detection) showed two peaks, ascribed to degradation intermediates. The maximum percentage of total organic carbon removed was 12.9%. Ion chromatography revealed that higher concentrations of nitrate and nitrite ions formed with increasing current density.

Emissões naturais e antrópicas de nitrogênio, fósforo e metais para a bacia do Rio Macaé (Macaé, RJ, Brasil) sob influência das atividades de exploração de petroleo e gás na Bacia de Campos

Emission factors of natural processes and anthropogenic activities were used to estimate nutrients and metal loads for the lower Macaé river basin, which hosts the operational base for the offshore oil and gas exploration in the Campos Basin. The estimates indicated that emissions from anthropogenic activities are higher than natural emissions. Major contributing drivers include husbandry and urbanization, whose effluents receive no treatment. The increasing offshore oil exploration along the Brazilian littoral has resulted in rapid urbanization and, therefore might increase the inshore emission of anthropogenic chemicals in cases where effective residue control measures are not implemented in fluvial basins of the region.

Time-series forecasting of pollutant concentration levels using particle swarm optimization and artificial neural networks

This study evaluates the application of an intelligent hybrid system for time-series forecasting of atmospheric pollutant concentration levels. The proposed method consists of an artificial neural network combined with a particle swarm optimization algorithm. The method not only searches relevant time lags for the correct characterization of the time series, but also determines the best neural network architecture. An experimental analysis is performed using four real time series and the results are shown in terms of six performance measures. The experimental results demonstrate that the proposed methodology achieves a fair prediction of the presented pollutant time series by using compact networks.

Method for determining the photocatalytic potential of portland cement mortar containing TiO2 for decomposing the pollutant nitrogen monoxide

Photocatalytic materials can minimize atmospheric pollution by decomposing certain organic and inorganic pollutants using sunlight as an energy source. In this paper, the development of a methodology to measure the photocatalytic potential of mortar containing TiO2 nanoparticles is reported. The results indicate that up to 40% of NOx can be degraded by Portland cement mortar containing 30-50% of TiO2, which validates the method developed for evaluating the photocatalytic potential of materials.

Química entre a microcamada superficial oceânica e os aerossóis marinhos

The sea surface microlayer (SML), although poorly understood, is important in biogeochemical cycling and sea - air exchanges; it is a source or a sink for a range of pollutants. In this paper, an overview of sampling techniques and the role of SML in biogeochemical cycles and climate is presented. The chemical and biological nature of the ocean surface film and its interaction with atmospheric aerosols are discussed. Special attention is given to organic constituents, gel-like compounds, surfactants, halogenated compounds, and metals. Estimates of air - sea exchange fluxes-with focus on organic carbon, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls-are compiled. In addition, research gaps in the chemical composition of marine aerosols and their relationship with SML are described.

Particulate matter in the indoor environment of museums in the megacity of São Paulo

Atmospheric pollutants can have serious impacts on the preservation of São Paulo's tangible cultural heritage. The purpose of this paper is to report the results of a monitoring campaign focussed on particulate matter (PM) that was conducted in three of the most important museums of the São Paulo megacity (Brazil): the Museu de Arqueologia e Etnologia (MAE-USP), the Museu Paulista (MP-USP), and the Pinacoteca do Estado de São Paulo (PE). These museums exhibit indoor PM and black carbon (BC) concentrations consistent with their urban locations and their specific methods for managing the indoor environment.

APLICAÇÃO DE ÓXIDOS DE FERRO NANOESTRUTURADOS COMO ADSORVENTES E FOTOCATALISADORES NA REMOÇÃO DE POLUENTES DE ÁGUAS RESIDUAIS

New techniques for treating wastewater, particularly the removal or degradation of organic pollutants and heavy metals, among other pollutants, have been extensively studied. The use of nanostructured iron oxides as adsorbent and photocatalyst for the removal of these contaminants has proved a promising approach, not only because of their high treatment efficiency, but also for their cost-effectiveness, having the flexibility for in situ and ex situ applications. In this review, we briefly introduced the most used kinds of iron oxide nanoparticles, some synthesis techniques for iron oxide nanostructure formation, their potential benefits in environmental clean-up, and their recent advances and applications in wastewater treatment. These advances range from the direct applications of synthesized nanoparticles as adsorbents for removing toxic contaminants or as catalysts to oxidize and break down noxious contaminants (including bacteria and viruses) in wastewater, to integrating nanoparticles into conventional treatment technologies, such as composite photocatalytic filters (membranes, sand and ceramic) that combine separation technology with photocatalytic activity. Finally, the impact of nanoparticles on the environment and human health is briefly discussed.

MICROEMULSÕES: COMPONENTES, CARACTERÍSTICAS, POTENCIALIDADES EM QUÍMICA DE ALIMENTOS E OUTRAS APLICAÇÕES

Microemulsions (MEs) are thermodynamically stable systems consisting of nanosized droplets dispersed in a solvent continuous medium (known as pseudo-phase), which is immiscible with the dispersed phase. These systems consist of water, a hydrophobic solvent called "oil," an amphiphile and often, a co-surfactant that is normally a medium chain alcohol. A large number of publications describe the importance of MEs in many branches of chemistry, and there is an intensive search for new applications. In addition, MEs have been applied in many areas, including oil extraction, removal of environmental pollutants from soils and effluents, dissolution of additives in lubricants and cutting oils, cleaning processes, dyeing and textile finishing, as nanoreactors to obtain nanoparticles of metals, semiconductors, superconductors, magnetic and photographic materials, and latex. However, only some studies indicate the potential applications of MEs in food and even fewer evaluate their chemical behavior. Potential applications of MEs in food comprise dissolution of lipophilic additives, stabilization of nutrients and biologically active compounds, using as an antimicrobial agent and to maximize the efficiency of food preservatives. This work consists of a literature review focusing on composition and physical and chemical characteristics of microemulsions. Despite the small number of studies on the subject reported in the literature, we demonstrate some potential applications of MEs in food chemistry.

Pollution trends using bark of morus alba in the cities of buenos aires and mendoza (Argentina)

A comparative study of elements deposited on tree bark was carried out for urban and periurban areas of two of the most important cities in Argentina. The content of Fe, Mg, Al, Mn, Zn, Pb, Ba, Cr, Hg, Cu, Ni, Cd and Sb was determined by inductively coupled plasma atomic emission spectrometry (ICP-OES) in Morus alba tree bark collected in the cities of Buenos Aires and Mendoza. The main air pollutants detected in the Buenos Aires urban area were Ba, Cr, Cu and Ni and indicate significative difference from the Mendoza urban and periurban areas. Significantly, higher concentrations of Zn, Ba, Cr and Cu were recorded in the periurban area of the city of Buenos Aires than in Mendoza. Bark samples were strongly influenced by dust and show Al, Fe, Mg and other element accumulations that indicate that soil particles were carried out by wind. Elements like Ba and Zn, commonly linked to traffic emissions, showed the highest concentrations in the Buenos Aires metropolitan area, possibly due to more intensive vehicular traffic. Our results indicated that intensity of vehicular traffic and not city structure is responsible for air pollution.

Development of bean plants in soil contaminated with trifloxysulfuron-sodium after Stizolobium aterrimum and Canavalia ensiformis cultivation

Phytoremediation, the use of plants to decontaminate soils and water resources from organic pollutants such as herbicides, is economically and environmentally a promising technique applied in many areas, including agriculture. The objective of this work was to evaluate the development of bean plants cultivated in the field, in soil with different levels of trifloxysulfuron-sodium contamination, following cultivation of two green manure species, as well as to evaluate the possibility of recontamination of the area by such herbicide with the straw permanence on the soil. The experiment was carried out in Coimbra, MG, Brazil, on a sandy clayey Red - Yellow Argisol from March to November 2003. Four levels of soil contamination with trifloxysulfuron-sodium (0.00; 3.75; 7.50; and 15.00 g ha-1) were used as well as the following five types of cultivation prior to bean sowing in the area after herbicide application: black velvet beans (Stizolobium aterrimum) followed by removal of straw; S. aterrimum, followed by permanence of straw; jack bean (Canavalia ensiformis), followed by removal of straw; C. ensiformis followed by permanence of straw; and without prior cultivation, weed-free (weeded control). The leguminous plants were kept in the area for 65 days, cut close to the soil, and with its aerial part left or not on the surface of the experimental plot, depending on the treatment. Fifteen days after the species were cut, bean was sown in the area. At 45 days after emergence (DAE) of the bean plants, plant height and dry mass of the aerial part were evaluated. Grain productivity was determined during harvest. Height, dry matter of the aerial part and grain productivity of the bean plants, cultivated in an area previously contaminated with trifloxysulfuron-sodium at any of the levels tested, were higher with prior cultivation of S. aterrimum or C. ensiformis. At the lowest level of herbicide contamination, prior cultivation of C. ensiformis was found to be more efficient than that of S. aterrimum in mitigating the harmful effects of trifloxysulfuron-sodium on bean grain production. The permanence of the straw of the green manure species during the bean cycle did not harm the development of the plants or caused culture productivity losses, indicating that straw permanence in the area does not promote recontamination of the area.

Megaspore germination and initial development of Regnellidium diphyllum Lindman (Pteridophyta, Marsileaceae) sporophytes in the presence of cadmium

Regnellidium diphyllum has its distribution restricted to Southern Brazil and adjoining localities in Uruguay and Argentina. Currently it is on the list of threatened species of Rio Grande do Sul. The conversion of wetlands into agricultural areas or soil contamination by the introduction of waste products and fertilizers may compromise the establishment and survival of this species. Among the pollutants are heavy metals, such as cadmium (Cd). Megaspores were germinated in liquid culture medium, with concentrations 0 (control), 0.39; 0.78; 1.56; 3.12; 6.25; 12.5; 25; 50 and 100 mg L-1 of Cd, starting from a standard solution of Titrisol® at 1000 mg L-1. The increase of Cd in the growth medium to 50 mg L-1 resulted in low germinability (58%), and no germination was observed on 100 mg L-1. In apomictical sporophytes, the growth of primary root and leaf was significantly reduced and no secondary leaf was formed at Cd concentrations of 12.5 and higher than this. The results indicated that R. diphyllum is tolerant to the presence of Cd up to considerably higher concentrations (0.78 mg L-1) than that normally found in unpolluted aquatic ecosystems (0.01 mg L-1), although the sensitivity to higher concentrations might endanger the establishment and permanence of this species in habitats exposed to contamination with this metal.

Effects of formaldehyde on the frog's mucociliary epithelium as a surrogate to evaluate air pollution effects on the respiratory epithelium

The increasing use of alcohol as an alternative fuel to gasoline or diesel can increase emission of formaldehyde, an organic gas that is irritant to the mucous membranes. The respiratory system is the major target of air pollutants and its major defense mechanism depends on the continuous activity of the cilia and the resulting constant transportation of mucous secretion. The present study was designed to evaluate the effects of formaldehyde on the ciliated epithelium through a relative large dose range around the threshold limit value adopted by the Brazilian legislation, namely 1.6 ppm (1.25 to 5 ppm). For this purpose, the isolated frog palate preparation was used as the target of toxic injury. Four groups of frog palates were exposed to diluted Ringer solution (control, N = 8) and formaldehyde diluted in Ringer solution at three different concentrations (1.25, 2.5 and 5.0 ppm, N = 10 for each group). Mucociliary clearance and ciliary beat frequency decreased significantly in contact with formaldehyde at the concentrations of 2.5 and 5.0 ppm after 60 min of exposure (P<0.05). We conclude that relatively low concentrations of formaldehyde, which is even below the Brazilian threshold limit value, are sufficient to cause short-term mucociliary impairment.

Air pollution and neonatal deaths in São Paulo, Brazil

Air pollution has been associated with health effects on different age groups. The present study was designed to assess the impact of daily changes in air pollutants (NO2, SO2, CO, O3, and particle matter (PM10)) on total number of daily neonatal deaths (those that occur between the first and the 28th days of life) in São Paulo, from January 1998 to December 2000, since adverse outcomes such as neonatal deaths associated with air pollution in Brazil have not been evaluated before. Generalized additive Poisson regression models were used and nonparametric smooth functions (loess) were adopted to control long-term trend, temperature, humidity, and short-term trends. A linear term was used for holidays. The association between air pollutants and neonatal deaths showed a short time lag. Interquartile range increases in PM10 (23.3 µg/m³) and SO2 (9.2 µg/m³) were associated with increases of 4% (95% CI, 2-6) and 6% (95% CI, 4-8), respectively. Instead of adopting a two-pollutant model we created an index to represent PM10 and SO2 effects. For an interquartile range increase in the index an increase of 6.3% (95% CI, 6.1-6.5) in neonatal deaths was observed. These results agree with previous studies performed by our group showing the deleterious effects of air pollutants during the perinatal period. The method reported here represents an alternative approach to analyze the relationship between highly correlated pollutants and public health problems, reinforcing the idea of the synergic effects of air pollutants in public health.