Determination of urban volatile organic compound emission ratios and comparison with an emissions database. Journal of Geophysical Research, 112, D10S47

Journal of Geophysical Research-Atmospheres 05/2007; 112(D10):D10S47. DOI: 10.1029/2006JD007930


During the NEAQS-ITCT2k4 campaign in New England, anthropogenic VOCs and CO were measured downwind from New York City and Boston. The emission ratios of VOCs relative to CO and acetylene were calculated using a method in which the ratio of a VOC with acetylene is plotted versus the photochemical age. The intercept at the photochemical age of zero gives the emission ratio. The so determined emission ratios were compared to other measurement sets, including data from the same location in 2002, canister samples collected inside New York City and Boston, aircraft measurements from Los Angeles in 2002, and the average urban composition of 39 U.S. cities. All the measurements generally agree within a factor of two. The measured emission ratios also agree for most compounds within a factor of two with vehicle exhaust data indicating that a major source of VOCs in urban areas is automobiles. A comparison with an anthropogenic emission database shows less agreement. Especially large discrepancies were found for the C2-C4 alkanes and most oxygenated species. As an example, the database overestimated toluene by almost a factor of three, which caused an air quality forecast model (WRF-CHEM) using this database to overpredict the toluene mixing ratio by a factor of 2.5 as well. On the other hand, the overall reactivity of the measured species and the reactivity of the same compounds in the emission database were found to agree within 30%.

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    • "The possible explanations for the underestimation of carbonyl emissions included (1) underestimation of the carbonyl emission factors for vehicle exhaust and/or (2) underestimation of carbonyl emissions from other sources (Borbon et al., 2013; Warneke et al., 2007). In the inventory built by Li et al. (2014), the VOC emission factors and profiles for gasoline and diesel vehicular exhaust were measured in China (Liu et al., 2008), and thus the uncertainty of transportation-related VOC emissions was relatively low. "
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    ABSTRACT: Carbonyl compounds are important intermediates in atmospheric photochemistry, but their primary sources are still not understood well. In this work, carbonyls, hydrocarbons, and alkyl nitrates were continuously measured during November 2011 at a rural site in the Yangtze River Delta region of China. Mixing ratios of carbonyls and hydrocarbons showed large fluctuations during the entire measurement. The average level for total measured volatile organic compounds during the pollution episode from 25th to 27th November, 2011 was 91.6 ppb, about 7 times the value for the clean period of 7th–8th, November, 2011. To preliminarily identify toluene sources at this site, the emission ratio of toluene to benzene (T/B) during the pollution episode was determined based on photochemical ages derived from the relationship of alkyl nitrates to their parent alkanes. The calculated T/B was 5.8 ppb/ppb, significantly higher than the values of 0.2–1.7 ppb/ppb for vehicular exhaust and other combustion sources, indicating the dominant influence of industrial emissions on ambient toluene. The contributions of industrial sources to ambient carbonyls were then calculated using a multiple linear regression fit model that used toluene and alkyl nitrates as respective tracers for industrial emission and secondary production. During the pollution episode, 18.5%, 69.0%, and 52.9% of measured formaldehyde, acetaldehyde, and acetone were considered to be attributable to industrial emissions. The emission ratios relative to toluene for formaldehyde, acetaldehyde, and acetone were determined to be 0.10, 0.20 and 0.40 ppb/ppb, respectively. More research on industrial carbonyl emission characteristics is needed to understand carbonyl sources better.
    Journal of Environmental Sciences 12/2014; 28. DOI:10.1016/j.jes.2014.12.001 · 2.00 Impact Factor
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    • "ies carried out in urban areas and near streets with a heavy traffic flow ( Barletta et al . 2005 ; Hoque et al . 2008 ; Khoder 2007 ; Wang and Zhao 2008 ) , implying that traffic is the main source of these compounds . Nevertheless , other works in urban areas have reported even higher ratios of T / B ( Elbir et al . 2007 ; Gee and Sollars 1998 ; Warneke et al . 2007"
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    ABSTRACT: Diffusive samplers were used to measure the vertical concentrations of benzene, toluene, n-hexane, cyclohexane, ethylbenzene and o-, m- and p-xylenes on both sides of two NS-oriented street canyons in Murcia (Spain) during a 5-day period. Non-dimensional relationships of concentration and height were calculated in order to study the behaviour of their concentration vertical profiles. The results show that the vertical profiles of benzene, toluene, n-hexane and cyclohexane concentrations were similar in both streets and on both sides of each street. Some differences were found in vertical profiles between streets and sides for ethylbenzene and xylenes, probably due to their higher affinity for adsorption into building materials. The similarities found for the first set of VOCs suggest that the dynamics of the dispersion was the same for both streets and was mainly influenced by microscale thermal effects. Finally, the concentration measurements of benzene, toluene, n-hexane, cyclohexane, and ethylbenzene were adjusted to expressions in the form c = c (0)(h/h (0))( A ), and a regression coefficient R (2) = 0.962 (p = 0.0000) was obtained. The decreasing concentration of these compounds with height should be taken into account when assessing population exposure to these pollutants.
    Environmental Monitoring and Assessment 02/2012; 184(12). DOI:10.1007/s10661-011-2504-x · 1.68 Impact Factor
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    • "Propyne was not detectable in any of the samples that we collected during Flight 23. Ethyne – a tracer of incomplete combustion by biomass burning and urban fossil fuel (Blake et al., 2003; Warneke et al., 2007) – correlated most strongly with ethene, NO y , NO and the trimethylbenzenes (0.91≤r 2 ≤0.96) and showed a maximum mixing ratio of 138 pptv over the oil sands, compared to 59±5 pptv in the local background 10 (Table 1; Fig. 6f). As with the alkenes, this enhancement is small compared to average levels measured in Houston (473 pptv; Gilman et al., 2009) and in the 28 US city study (260–2390 pptv; Baker et al., 2008), indicating the relatively low impact of industrial combustion on the measured ethyne levels. "
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    ABSTRACT: Oil sands comprise 30% of the world's oil reserves and the crude oil reserves in Canada's oil sands deposits are second only to Saudi Arabia. The extraction and processing of oil sands is much more challenging than for light sweet crude oils because of the high viscosity of the bitumen contained within the oil sands and because the bitumen is mixed with sand and contains chemical impurities such as sulphur. Despite these challenges, the importance of oil sands is increasing in the energy market. To our best knowledge this is the first peer-reviewed study to characterize volatile organic compounds (VOCs) emitted from Alberta's oil sands mining sites. We present high-precision gas chromatography measurements of 76 speciated C2-C10 VOCs (alkanes, alkenes, alkynes, cycloalkanes, aromatics, monoterpenes, oxygenated hydrocarbons, halocarbons and sulphur compounds) in 17 boundary layer air samples collected over surface mining operations in northeast Alberta on 10 July 2008, using the NASA DC-8 airborne laboratory as a research platform. In addition to the VOCs, we present simultaneous measurements of CO2, CH4, CO, NO, NO2, NOy, O3 and SO2, which were measured in situ aboard the DC-8. Carbon dioxide, CH4, CO, NO, NO2, NOy, SO2 and 53 VOCs (e.g., non-methane hydrocarbons, halocarbons, sulphur species) showed clear statistical enhancements (1.1-397×) over the oil sands compared to local background values and, with the exception of CO, were greater over the oil sands than at any other time during the flight. Twenty halocarbons (e.g., CFCs, HFCs, halons, brominated species) either were not enhanced or were minimally enhanced (
    ATMOSPHERIC CHEMISTRY AND PHYSICS 12/2010; 10(23):11931-11954. DOI:10.5194/acp-10-11931-2010 · 5.05 Impact Factor
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