In this study, particulate matter (PM) were characterized from a place impacted by heavy-duty vehicles (Bus Station) fuelled with diesel/biodiesel fuel blend (B3) in the city of Londrina, Brazil. Sixteen priority polycyclic aromatic hydrocarbons (PAH) concentrations were analyzed in the samples by their association with atmospheric PM, mass size distributions and major ions (fluorite, chloride, bromide, nitrate, phosphate, sulfate, nitrite, oxalate; fumarate, formate, succinate and acetate; lithium, sodium, potassium, magnesium, calcium and ammonium). Results indicate that major ions represented 21.2% particulate matter mass. Nitrate, sulfate, and ammonium, respectively, presented the highest concentration levels, indicating that biodiesel may also be a significant source for these ions, especially nitrate. Dibenzo[a,h]anthracene and indeno[1,2,3,-cd]pyrene were the main PAH found, and a higher fraction of PAH particles was found in diameters lower than 0.25 μm in Londrina bus station. The fine and ultrafine particles were dominant among the PM evaluated, suggesting that biodiesel decreases the total PAH emission. However, it does also increase the fraction of fine and ultrafine particles when compared to diesel.

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Compostos orgânicos voláteis (COV) tem papel significativo no processo de formação do smog fotoquímico. Os fotooxidantes são formados na atmosfera quando os COV reagem com óxidos de nitrogênio em presença da luz solar e radicais OH. Em áreas urbanas, veículos são uma importante fonte de COV e NO x para a atmosfera, tanto pela queima quanto por evaporação de combustíveis. Neste trabalho são comparados dois tipos de combustível atualmente usados no Brasil -etanol hidratado (95% v/v) e gasool (uma mistura de 22-24% de etanol anidro em gasolina) -em termos de precursores na formação de ozônio na atmosfera de cidades urbanas. Os experimentos foram feitos durante a primavera e verão de 2001/2002 e, em cada um, foram preenchidas duas bolsas de Teflon com cada um dos combustíveis, respectivamente, e altas razões iniciais [COV]/ [NO], sendo a seguir as mesmas expostas à luz solar. Tanto a formação de ozônio quanto os perfis de concentração de NOx foram medidos diretamente com o uso de analisadores contínuos de ozônio e NO/NO 2 /NOx, respectivamente Os resultados mostraram que para os mesmos volumes iniciais de combustível em cada bolsa, as concentrações máximas de ozônio eram em média 28% maiores para o álcool do que para o gasool. Além disso, o processo de formação do ozônio iniciava-se antes para o gasool mas, uma vez iniciado em ambos os combustíveis, a taxa de formação tendia a ser duas vezes maior para o álcool, em comparação ao gasool. Tais observações indicam a necessidade de estudos mais detalhados, a respeito do papel das emissões derivadas de evaporação e combustível não queimado, nos processos de formação de oxidantes fotoquímicos na atmosfera, com atenção especial aos aspectos cinéticos. Isto é particularmente importante para o caso do Brasil, considerando-se a contribuição substancial dessas emissões para o inventário de hidrocarbonetos (HC) e COV, provenientes de fontes móveis em grandes cidades, e uma possível retomada do Programa Brasileiro de Biocombustíveis, a qual levaria a um aumento nas concentrações atmosféricas de etanol.Volatile organic compounds (VOC) play a significative role on the process of formation of photochemical smog. Photooxidants are formed in the atmosphere when VOC react with nitrogen oxides (NOx), in the presence of sunlight and OH radicals. In urban areas, vehicle fuels constitute an important source of VOC and NOx emissions to the atmosphere, either by burning or evaporative losses. This work is concerned with a comparative study of two types of light-duty vehicular fuels presently used in Brazil -namely gasohol (a mixture 22-24% of anhydrous ethanol in gasoline) and hydrated ethanol (95% v/v) -as potential precursors for ozone formation in the atmosphere of urban cities. The experiments were conducted during the spring and summer of 2001/2002. In each one, two Teflon chambers were filled, respectively, with each fuel, at high initial [VOC] to [NO] ratios and exposed to the sunlight. Ozone formation, as well as NOx concentration profiles were measured directly using ozone and NO/N...

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A new analytical method is reported for the determination of 11 volatile carbonyl compounds isolated at room temperature from the headspace of marine algae. This method is based on the conversion of the carbonyl compounds to their 2,4-dinitrophenylhydrazone derivatives followed by high-performance liquid chromatography analysis. Using this method, 11 carbonyl compounds are detected and identified from the dynamic headspace sampling of 10 species of marine algae. Eight compounds are quantitated and the three remaining are only identified. Under optimized conditions, all carbonyl compounds are separated in 32 min. The detection and quantitation limits of the high-performance liquid chromatography method are, respectively, in the range of 0.26-0.85 ng/g of algae (formaldehyde) to 13.77-45.90 ng/g of algae (E)-2-hexenal. The calibration curves are linear in the concentration range of 2.0-1000 microg/L of solution, corresponding to 0.34-170.00 ng/g of algae. Acetaldehyde and propanal are the most abundant carbonyl compounds identified, with concentrations as high as 980 and 790 ng/g, respectively. The present work, as far as we know, is the first analytical methodology that has been developed to determine low-molecular-weight carbonyl compounds in marine algae. Because many species of marine algae are used as human food, the reported method should be useful to investigators studying the nutritional value as well as oxidative spoilage of fresh and preserved marine algae that is destined for human consumption.

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