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(409) Atmospheric transformation products of PAHs and alkyl-PAHs emitted from diesel engines.
Reisen, Fabienne*,1, Arey, Janet1, 1 University of California, Riverside, Riverside, CA, USA
ABSTRACT- Recent ambient measurements taken in a traffic-impacted area in Los Angeles, CA, revealed the presence of isomers of alkylated polycyclic aromatic hydrocarbons (PAHs) which have also been identified in diesel fuel. This and other evidence indicate that PAHs from unburned fuel are an important constituent of diesel exhaust. The semi-volatile PAHs and alkyl-PAHs emitted into the atmosphere can undergo gas-phase reactions with hydroxyl (OH) radicals, nitrate (NO3) radicals and ozone. The objectives of the research are to investigate the atmospheric transformation products of selected PAHs present in diesel fuel or diesel exhaust and measured in the ambient atmosphere and to analyze ambient air for selected of the major atmospheric reaction products identified. The experiments are carried out in a 7000-liter Teflon environmental chamber for controlled atmospheric simulations. To date, the atmospheric transformation processes of the OH radical-initiated reactions with acenaphthene and acenaphthylene and of the O3 reaction with acenapthylene have been investigated. Some of the products we were able to identify are dialdehydes, nitro-derivatives and carbonyl compounds. Atmospheric reactions with volatilized diesel fuel have been carried out. The products include nitro-PAHs, oxygenated derivatives and carbonyl compounds. Some of the isomers of the dimethylnitronaphthalenes, formed in the NO3 radical-initiated reactions with volatilized diesel fuel, have been measured in ambient air samples.
Key words: PAHs, alkyl-PAHs, diesel fuel, atmospheric reactions
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