Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data
Mobile emissions represent a significant fraction of the total anthropogenic emissions burden in the Mexico City Metropolitan Area (MCMA) and, therefore, it is crucial to use top-down techniques informed by on-road exhaust measurements to evaluate and improve traditional bottom-up official emissions...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | en_US |
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European Geosciences Union / Copernicus
2011
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| Online Access: | http://hdl.handle.net/1721.1/65346 https://orcid.org/0000-0002-3596-5334 |
| _version_ | 1826192780275220480 |
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| author | Zavala-Perez, Miguel Angel Herndon, S. C. Wood, E. C. Onasch, T. B. Knighton, W. Berk Kolb, Charles E. Molina, Luisa Tan |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Zavala-Perez, Miguel Angel Herndon, S. C. Wood, E. C. Onasch, T. B. Knighton, W. Berk Kolb, Charles E. Molina, Luisa Tan |
| author_sort | Zavala-Perez, Miguel Angel |
| collection | MIT |
| description | Mobile emissions represent a significant fraction of the total anthropogenic emissions burden in the Mexico City Metropolitan Area (MCMA) and, therefore, it is crucial to use top-down techniques informed by on-road exhaust measurements to evaluate and improve traditional bottom-up official emissions inventory (EI) for the city. We present the measurements of on-road fleet-average emission factors obtained using the Aerodyne mobile laboratory in the MCMA in March 2006 as part of the MILAGRO/MCMA-2006 field campaign. A comparison of our on-road emission measurements with those obtained in 2003 using essentially the same measurement techniques and analysis methods indicates that, in the three year span, NO emission factors remain within the measured variability ranges whereas emission factors of aldehydes and aromatics species were reduced for all sampled driving conditions.
We use a top-down fuel-based approach to evaluate the mobile emissions from the gasoline fleet estimated in the bottom-up official 2006 MCMA mobile sources. Within the range of measurement uncertainties, we found probable slight overpredictions of mean EI estimates on the order of 20–28% for CO and 14–20% for NO. However, we identify a probable EI underprediction of VOC mobile emissions between 1.4 and 1.9; although estimated benzene and toluene mobile emissions in the inventory seem to be well within the uncertainties of the corresponding emissions estimates. Aldehydes mobile emissions in the inventory, however, seem to be under predicted by factors of 3 for HCHO and 2 for CH3CHO [CH subscript 3 CHO]. Our on-road measurement based estimate of annual emissions of organic mass from PM1 particles suggests a severe underprediction (larger than a factor of 4) of PM2.5 [PM subscript 2.5] mobile emissions in the inventory.
Analyses of ambient CO, NOx [NO subscript x] and CO/NOx [CO/NO subscript x] concentration trends in the MCMA indicate that the early morning ambient CO/NOx [CO/NO subscript x] ratio has decreased at a rate of about 1.9 ppm/ppm/year over the last two decades and that the decrease has been driven by reductions in CO levels rather than by NOx [NO subscript x] concentration changes, suggesting that the relative contribution of diesel vehicles to overall NOx [NO subscript x] levels has increased over time in the city. Despite the impressive increases in the size of the vehicle fleet between 2000 and 2006, the early morning ambient concentrations of CO and NOx [NO subscript x] have not increased accordingly, probably due to the reported low removal rates of older vehicles, which do not have emissions control technologies, and partially due to the much lower emissions from newer gasoline vehicles. This indicates that an emission-based air quality control strategy targeting large reductions of emissions from mobile sources should be directed towards a significant increase of the removal rate of older, highly-polluting, vehicles. |
| first_indexed | 2024-09-23T09:29:05Z |
| format | Article |
| id | mit-1721.1/65346 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T09:29:05Z |
| publishDate | 2011 |
| publisher | European Geosciences Union / Copernicus |
| record_format | dspace |
| spelling | mit-1721.1/653462022-09-26T11:41:23Z Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data Zavala-Perez, Miguel Angel Herndon, S. C. Wood, E. C. Onasch, T. B. Knighton, W. Berk Kolb, Charles E. Molina, Luisa Tan Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Molina, Luisa Tan Zavala-Perez, Miguel Angel Molina, Luisa Tan Mobile emissions represent a significant fraction of the total anthropogenic emissions burden in the Mexico City Metropolitan Area (MCMA) and, therefore, it is crucial to use top-down techniques informed by on-road exhaust measurements to evaluate and improve traditional bottom-up official emissions inventory (EI) for the city. We present the measurements of on-road fleet-average emission factors obtained using the Aerodyne mobile laboratory in the MCMA in March 2006 as part of the MILAGRO/MCMA-2006 field campaign. A comparison of our on-road emission measurements with those obtained in 2003 using essentially the same measurement techniques and analysis methods indicates that, in the three year span, NO emission factors remain within the measured variability ranges whereas emission factors of aldehydes and aromatics species were reduced for all sampled driving conditions. We use a top-down fuel-based approach to evaluate the mobile emissions from the gasoline fleet estimated in the bottom-up official 2006 MCMA mobile sources. Within the range of measurement uncertainties, we found probable slight overpredictions of mean EI estimates on the order of 20–28% for CO and 14–20% for NO. However, we identify a probable EI underprediction of VOC mobile emissions between 1.4 and 1.9; although estimated benzene and toluene mobile emissions in the inventory seem to be well within the uncertainties of the corresponding emissions estimates. Aldehydes mobile emissions in the inventory, however, seem to be under predicted by factors of 3 for HCHO and 2 for CH3CHO [CH subscript 3 CHO]. Our on-road measurement based estimate of annual emissions of organic mass from PM1 particles suggests a severe underprediction (larger than a factor of 4) of PM2.5 [PM subscript 2.5] mobile emissions in the inventory. Analyses of ambient CO, NOx [NO subscript x] and CO/NOx [CO/NO subscript x] concentration trends in the MCMA indicate that the early morning ambient CO/NOx [CO/NO subscript x] ratio has decreased at a rate of about 1.9 ppm/ppm/year over the last two decades and that the decrease has been driven by reductions in CO levels rather than by NOx [NO subscript x] concentration changes, suggesting that the relative contribution of diesel vehicles to overall NOx [NO subscript x] levels has increased over time in the city. Despite the impressive increases in the size of the vehicle fleet between 2000 and 2006, the early morning ambient concentrations of CO and NOx [NO subscript x] have not increased accordingly, probably due to the reported low removal rates of older vehicles, which do not have emissions control technologies, and partially due to the much lower emissions from newer gasoline vehicles. This indicates that an emission-based air quality control strategy targeting large reductions of emissions from mobile sources should be directed towards a significant increase of the removal rate of older, highly-polluting, vehicles. Atmospheric Sciences Program (U.S.) (DE-FG02-05ER63980) Atmospheric Sciences Program (U.S.) (DE-FG02-05ER63982) United States. Dept. of Energy National Science Foundation (U.S.) (Atmospheric chemistry program ATM-0528170) National Science Foundation (U.S.) (Atmospheric chemistry program ATM-528227) 2011-08-19T18:51:57Z 2011-08-19T18:51:57Z 2009-03 2009-02 Article http://purl.org/eprint/type/JournalArticle 1680-7324 1680-7316 http://hdl.handle.net/1721.1/65346 Zavala, M. et al. “Evaluation of Mobile Emissions Contributions to Mexico City’s Emissions Inventory Using On-road and Cross-road Emission Measurements and Ambient Data.” Atmospheric Chemistry and Physics Discussions 9.2 (2009) : 6363-6395. © Author(s) 2009 https://orcid.org/0000-0002-3596-5334 en_US http://dx.doi.org/10.5194/acpd-9-6363-2009 Atmospheric Chemistry and Physics Creative Commons Attribution 3.0 http://creativecommons.org/licenses/by/3.0 application/pdf European Geosciences Union / Copernicus Copernicus |
| spellingShingle | Zavala-Perez, Miguel Angel Herndon, S. C. Wood, E. C. Onasch, T. B. Knighton, W. Berk Kolb, Charles E. Molina, Luisa Tan Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data |
| title | Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data |
| title_full | Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data |
| title_fullStr | Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data |
| title_full_unstemmed | Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data |
| title_short | Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data |
| title_sort | evaluation of mobile emissions contributions to mexico city s emissions inventory using on road and cross road emission measurements and ambient data |
| url | http://hdl.handle.net/1721.1/65346 https://orcid.org/0000-0002-3596-5334 |
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