“…Used engine oil contained, compared to new engine oil, enhanced concentrations of formic acid (CO and acetic acid (C2). Because no n-alkanoic acids in the range C5-C10 were found in engine oil and there is no indication that n-alkanoic acids are part of the fuels used, it is proposed that the higher alkanoic acids (C6-C22) quantified in vehicle exhaust (Table II) are formed during the combustion process ( 63) and/or catalytic oxidation process (catalyst auto only) (64). Given the relatively high emission rates of organic acids from the catalyst-equipped cars when compared to the noncatalyst cars, it is likely that the presence of the catalyst system enhances the formation of organic acids.…”
Gasoline-and diesel-powered vehicles are known to contribute appreciable amounts of inhalable fine particulate matter to the atmosphere in urban areas. Internal combustion engines burning gasoline and diesel fuel contribute more than 21% of the primary fine particulate organic carbon emitted to the Los Angeles atmosphere. In the present study, particulate (dp < 2 µ ) exhaust emissions from six noncatalyst automobiles, seven catalystequipped automobiles, and two heavy-duty diesel trucks are examined by gas chromatography/mass spectrometry.The purposes of this study are as follows: (a) to search for conservative marker compounds suitable for tracing the presence of vehicular particulate exhaust emissions in the urban atmosphere, (b) to compile quantitative source profiles, and (c) to study the contributions of fine organic particulate vehicular exhaust to the Los Angeles atmosphere. More than 100 organic compounds are quantified, including n-alkanes, n-alkanoic acids, benzoic acids, benzaldehydes, PAH, oxy-PAH, steranes, pentacyclic triterpanes, azanaphthalenes, and others. Although fossil fuel markers such as steranes and pentacyclic triterpanes can be emitted from other sources, it can be shown that their ambient concentrations measured in the Los Angeles atmosphere are attributable mainly to vehicular exhaust emissions.
“…Used engine oil contained, compared to new engine oil, enhanced concentrations of formic acid (CO and acetic acid (C2). Because no n-alkanoic acids in the range C5-C10 were found in engine oil and there is no indication that n-alkanoic acids are part of the fuels used, it is proposed that the higher alkanoic acids (C6-C22) quantified in vehicle exhaust (Table II) are formed during the combustion process ( 63) and/or catalytic oxidation process (catalyst auto only) (64). Given the relatively high emission rates of organic acids from the catalyst-equipped cars when compared to the noncatalyst cars, it is likely that the presence of the catalyst system enhances the formation of organic acids.…”
Gasoline-and diesel-powered vehicles are known to contribute appreciable amounts of inhalable fine particulate matter to the atmosphere in urban areas. Internal combustion engines burning gasoline and diesel fuel contribute more than 21% of the primary fine particulate organic carbon emitted to the Los Angeles atmosphere. In the present study, particulate (dp < 2 µ ) exhaust emissions from six noncatalyst automobiles, seven catalystequipped automobiles, and two heavy-duty diesel trucks are examined by gas chromatography/mass spectrometry.The purposes of this study are as follows: (a) to search for conservative marker compounds suitable for tracing the presence of vehicular particulate exhaust emissions in the urban atmosphere, (b) to compile quantitative source profiles, and (c) to study the contributions of fine organic particulate vehicular exhaust to the Los Angeles atmosphere. More than 100 organic compounds are quantified, including n-alkanes, n-alkanoic acids, benzoic acids, benzaldehydes, PAH, oxy-PAH, steranes, pentacyclic triterpanes, azanaphthalenes, and others. Although fossil fuel markers such as steranes and pentacyclic triterpanes can be emitted from other sources, it can be shown that their ambient concentrations measured in the Los Angeles atmosphere are attributable mainly to vehicular exhaust emissions.
“…Other minor aerosol components shown in the profile were taken from Watson's (ref 10, page 96) leaded automobile exhaust profile fine-particle fraction, except for sulfates, which were estimated at 0.45 mg/mile for 0.05% S in the gasoline. The sulfate estimate is based on a scaleup of estimates by Pierson (29), who suggested 0.27 mg/mile sulfates from precatalyst cars using fuel with 0.03% S. 6 This is a composite profile estimated as follows: sulfate fraction from Laresgoiti and Springer (30); carbon fraction from Mulhbaier and Williams (31); other trace species from Watson (10) unleaded auto fine-particle profile (ignoring lead and bromine that were probably due to use of leaded fuel at some point). 0 Watson (ref 10, p^ge 101) diesel-truck fineparticle profile modified by insertion of carbon estimates from Cass et al (26).…”
s = [AT WA]-IAT W c (2)where s is a vector of estimated source contributions to the ambient samples, c is a vector of the concentrations of species i = 1,2, ..., n measured at the monitoring site,A is the matrix filaij appearing in eq 1, and W is a diagonal matrix of weighting factors. The weighting factors commonly employed are l/Q, where ui is the standard deviation of single determination of the concentration of species i in an ambient sample (4). Elements like iron and manganese might differ in absolute mass concentration by 2 orders of magnitude, yet both be measurable with the
“…A direct exhaust sampling method has also been used by Grimmer (28) and others (3,(29)(30)(31). The exhaust is cooled in one or a series of successively colder traps with a large cooling surface.…”
Representative dilution tube sampling techniques for particulate and gas phase vehicle emissions are described using Teflon filter media and XAD-2 resin. More than 90% of the total gas (C8-C18) and particulate direct acting Ames assay mutagenicity (TA 98) was found in the particulate phase. The gas and particulate phase material was fractionated by HPLC into nonpolar, moderately polar and highly polar chemical fractions. The moderately polar chemical fraction of the particulates contained more than 50% of the direct acting Ames assay mutagenicity for the total extract. The concentration of oxygenated polynuclear aromatic hydrocarbons (oxy-PAH) and nitrated PAH (nitro-PAH) identified in the moderately polar particulate fractions are given. Nitro-PAH account for most of the direct-acting (TA 98) Ames assay mutagenicity in these moderately polar fractions. Reactions and kinetic expressions for chemical conversion of PAH are presented. Chemical conversion of PAH to nitro-PAH during dilution tube sampling of particulates on Teflon filters and gases on XAD-2 resin is a minor problem (representing 10-20%, on the average, of the 1-nitropyrene found in extracts) at short (46 min) sampling times, at low sampling temperatures (42 degrees C), and in diluted exhaust containing 3 ppm NO2. Particulate emissions collected from dilution tubes on filter media appear to be representative of what is emitted in the environment as based upon a comparison of highway and laboratory studies.
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