No abstract

Air samples were collected in three well characterized locations in the city of Rio de Janeiro, Brazil: downtown, the idle and taxi way areas of the national airport and an urban forest, where the main emissions are from vehicular, aircraft and biogenic sources, respectively. Aldehydes and BTEX concentrations show a characteristic profile which may be attributed to the emission sources. Formaldehyde/acetaldehyde ratios, in the early morning, were 1.39, 0.62 and 2.22 in downtown, airport and forest, respectively. Toluene/benzene ratios, for downtown, airport and forest areas, were 1.11, 1.82 and 1.06, respectively. The results show that the impact of the urban emissions on the forest is negligible as well as the impact of aircraft emissions over the urban area.

A fim de determinar o impacto das emissões de aldeídos num aeroporto, sobre a qualidade do ar, foram determinadas as concentrações de acetaldeído e formaldeído nas áreas de pouso e decolagem do aeroporto nacional Santos-Dumont no Rio de Janeiro, Brazil. O aeroporto está localizado a aproximadamente 1 km do centro da cidade e, no ano de 2007, teve uma média de 70.000 pousos e decolagens. Foram coletadas 129 amostras no período de março a novembro de 2007. Para o formaldeído foram observadas concentrações no intervalo 2,6 a 10,3 µg m -3 e para o acetaldeído, no intervalo, 4,3 a 19,7 µg m -3 . Durante a manhã, as relações A/F (acetaldeído/ formaldeído, em unidades de massa) se encontraram no intervalo 0,7-1,0. Nos horários da tarde as concentrações de formaldeído foram menores e as de acetaldeído aumentaram. As concentrações de formaldeído e acetaldeído estão no mesmo intervalo que valores previamente obtidos para o centro da cidade e possivelmente não afetem a produção de ozônio a nível local.To estimate the impact of aldehyde emissions at an airport on the air quality, formaldehyde and acetaldehyde concentrations were measured in the idle and taxiway areas of the Santos-Dumont national airport in Rio de Janeiro. The airport is located about 1 km from downtown Rio de Janeiro and had an average of 70,000 landings and take-offs during 2007. A total of 129 samples were collected in the period from March to November 2007. Formaldehyde concentrations ranged from 2.6 to 10.3 µg m -3 , and acetaldehyde concentrations ranged from 4.3 to 19.7 µg m -3 . During the morning, A/F ratios (acetaldehyde/formaldehyde ratios, in mass units) were in the range 0.7-1.0. In the afternoon, formaldehyde concentrations were lower and acetaldehyde concentrations generally increased. Formaldehyde and acetaldehyde concentrations were in the same range than values previously published for downtown and may not affect ozone production in a local scale.Keywords: aircraft engine emissions, aldehydes, airport air quality IntroductionThe impact of aircraft emissions on air quality has been investigated in several recent studies. Perl et al. 1 estimated the emissions due to aircraft operations at a mid-sized French airport in 1987, 1990 and 1994 and suggested a perspective of future emissions under different scenarios. These results show that, currently, aircraft emissions may be considered negligible in comparison with those generated by surface transportation sources. However, in the long-term, aviation might be considered a growing air pollution problem.Literature data show that the critical stages for aircraft emissions are those when the aircraft is waiting on the ground (the taxi and idle phases). In these phases, aircraft engines do not operate at their optimum conditions and emit significant amounts of carbon monoxide and hydrocarbons. 2 Pison and Menut 2 presented a analysis modeling of the aircraft traffic emissions impact on the ozone concentrations over Paris. They used a volatile organic compound (VOC) speciation reported by the Europe...

Amorphous Nb2O5 was synthesized by combining niobium ethoxide with an amine surfactant. The material turned out to have a high surface area, 287 m2 g−1, and a homogeneous structure. The material was shown to be amorphous despite the heat treatment performed within a range of 150 to 550°C. The surface area of Nb2O5 reduced to 105 m2 g−1 after heat treating at 350°C. The activation energy of the Nb2O5 crystallization reaction was found to be 327 kJ mol−1. The surface area of Nb2O5 reduced significantly with heat treatment but it still improved the hydrogen kinetics since the desorption rate was 1.5 wt.% min−1. The addition of a small amount of amorphous Nb2O5 to magnesium hydride, throughout milling, helped overcoming limitations inherent to solid hydrogen storage.

No abstract

Data for speciated volatile organic compounds (VOC) evaluated in Santos-Dumont Airport and Antonio Carlos Jobim International Airport in Rio de Janeiro, Brazil, are reported. VOC were evaluated by gas chromatography with flame ionization detection (GC – FID) and mass spectrometry (GC – MS), following the U.S. EPA TO – 15 methodology. At Santos-Dumont Airport were quantified 1376 µg m-3 of VOCs 10 m from runway, 408 µg m-3 inside the airport building, and 116 µg m-3 outside the airport area. At the taxiway area of the International Airport a total of 190 µg m-3 of VOC were quantified. Toluene, the most abundant compound near the Santos-Dumont Airport runway, was obtained in a non-significative concentration outside the airport area. This fact suggests that this area is not noticeably impacted by air traffic. A computational model was developed using the OZIPR program and the SAPRC mechanism. Calculated ozone concentrations are higher than values for downtown area of Rio de Janeiro city. Simulated results show that, for the runway in Santos-Dumont Airport, olefins and aromatics contribute in 57% and 15%, respectively, to ozone formation, toluene being the major contributor. Cis-2-butene is the most reactive species regarding OH reaction.

Mathematical models allow evaluating air pollutants effects to the environment, being a relevant tool for planning and regulatory purposes. The present study aims to evaluate the air quality of Volta Redonda, Brazil, due to particulate matter emitted by stationary point sources of a large steel plant using meteorological data from three monitoring stations. A mathematical model was developed linking Matlab® and RStudio®, using the Gaussian dispersion equation and Google Maps to visualize the results. Observed data revealed southern, north-western and northern light prevailing winds that were used to simulate stable and unstable atmosphere conditions according Pasquill-Guifford classification. Results have exposed elevated concentrations of particulate matter in ambient air, reaching particularly Santa Cecilia neighbourhood. National air quality standards recently updated were partially met however numerous violations were indicated, considerably higher in Santa Cecilia station (47.98%), followed by Belmonte (6.69%) and Retiro (4.17%), indicating a forthcoming need for an update of the technologies and processes that emit particulate matter to improve the city air quality, preventing from environmental and human health effects.

No abstract