Eddy covariance flux measurements of pollutant gases in urban Mexico City
Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric chemistry and the role that cities play in regional and global chemical cycles. A...
| Main Authors: | , , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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European Geosciences Union / Copernicus
2011
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| Online Access: | http://hdl.handle.net/1721.1/65593 https://orcid.org/0000-0002-3596-5334 |
| _version_ | 1826204268663668736 |
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| author | Velasco, Erik Pressley, S. Grivicke, R. Allwine, E. Coons, T. Foster, W. Jobson, T. Westberg, H. Ramos, R. Hernandez, F. Molina, Luisa Tan Lamb, B. K. |
| 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 Velasco, Erik Pressley, S. Grivicke, R. Allwine, E. Coons, T. Foster, W. Jobson, T. Westberg, H. Ramos, R. Hernandez, F. Molina, Luisa Tan Lamb, B. K. |
| author_sort | Velasco, Erik |
| collection | MIT |
| description | Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric chemistry and the role that cities play in regional and global chemical cycles. As part of the MCMA-2003 study, we demonstrated the feasibility of using eddy covariance techniques to measure fluxes of selected volatile organic compounds (VOCs) and CO2 [CO subscript 2] from a residential district of Mexico City (Velasco et al., 2005a, b). During the MILAGRO/MCMA-2006 field campaign, a second flux measurement study was conducted in a different district of Mexico City to corroborate the 2003 flux measurements, to expand the number of species measured, and to obtain additional data for evaluation of the local emissions inventory. Fluxes of CO2 [CO subscript 2] and olefins were measured by the conventional EC technique using an open path CO2 [CO subscript 2] sensor and a Fast Isoprene Sensor calibrated with a propylene standard. In addition, fluxes of toluene, benzene, methanol and C2-benzenes [C subscript 2 - benzenes] were measured using a virtual disjunct EC method with a Proton Transfer Reaction Mass Spectrometer. The flux measurements were analyzed in terms of diurnal patterns and vehicular activity and were compared with the most recent gridded emissions inventory. In both studies, the results showed that the urban surface of Mexico City is a net source of CO2 [CO subscript 2] and VOCs with significant contributions from vehicular traffic. Evaporative emissions from commercial and other anthropogenic activities were significant sources of toluene and methanol. The data show that the emissions inventory is in reasonable agreement with measured olefin and CO2 [CO subscript 2] fluxes, while C2-benzenes [C subscript 2 - benzenes] and toluene emissions from evaporative sources are overestimated in the inventory. It appears that methanol emissions from mobile sources occur, but are not present in the mobile emissions inventory. |
| first_indexed | 2024-09-23T12:51:36Z |
| format | Article |
| id | mit-1721.1/65593 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T12:51:36Z |
| publishDate | 2011 |
| publisher | European Geosciences Union / Copernicus |
| record_format | dspace |
| spelling | mit-1721.1/655932022-09-28T10:31:54Z Eddy covariance flux measurements of pollutant gases in urban Mexico City Velasco, Erik Pressley, S. Grivicke, R. Allwine, E. Coons, T. Foster, W. Jobson, T. Westberg, H. Ramos, R. Hernandez, F. Molina, Luisa Tan Lamb, B. K. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Molina, Luisa Tan Velasco, Erik Molina, Luisa Tan Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric chemistry and the role that cities play in regional and global chemical cycles. As part of the MCMA-2003 study, we demonstrated the feasibility of using eddy covariance techniques to measure fluxes of selected volatile organic compounds (VOCs) and CO2 [CO subscript 2] from a residential district of Mexico City (Velasco et al., 2005a, b). During the MILAGRO/MCMA-2006 field campaign, a second flux measurement study was conducted in a different district of Mexico City to corroborate the 2003 flux measurements, to expand the number of species measured, and to obtain additional data for evaluation of the local emissions inventory. Fluxes of CO2 [CO subscript 2] and olefins were measured by the conventional EC technique using an open path CO2 [CO subscript 2] sensor and a Fast Isoprene Sensor calibrated with a propylene standard. In addition, fluxes of toluene, benzene, methanol and C2-benzenes [C subscript 2 - benzenes] were measured using a virtual disjunct EC method with a Proton Transfer Reaction Mass Spectrometer. The flux measurements were analyzed in terms of diurnal patterns and vehicular activity and were compared with the most recent gridded emissions inventory. In both studies, the results showed that the urban surface of Mexico City is a net source of CO2 [CO subscript 2] and VOCs with significant contributions from vehicular traffic. Evaporative emissions from commercial and other anthropogenic activities were significant sources of toluene and methanol. The data show that the emissions inventory is in reasonable agreement with measured olefin and CO2 [CO subscript 2] fluxes, while C2-benzenes [C subscript 2 - benzenes] and toluene emissions from evaporative sources are overestimated in the inventory. It appears that methanol emissions from mobile sources occur, but are not present in the mobile emissions inventory. National Science Foundation (U.S.) (Grant ATM-0528227) United States. Dept. of Energy (Award DE-FG02-05ER63980) Mexico. Comisión Ambiental Metropolitana Molina Center for Energy and the Environment 2011-09-01T16:05:22Z 2011-09-01T16:05:22Z 2009-10 2009-09 Article http://purl.org/eprint/type/JournalArticle 1680-7324 1680-7316 http://hdl.handle.net/1721.1/65593 Velasco, E. et al. “Eddy Covariance Flux Measurements of Pollutant Gases in Urban Mexico City.” Atmospheric Chemistry and Physics Discussions 9.2 (2009) : 7991-8034. © Author(s) 2009 https://orcid.org/0000-0002-3596-5334 en_US http://dx.doi.org/10.5194/acpd-9-7991-2009 Atmospheric Chemistry and Physics Creative Commons Attribution 3.0 http://creativecommons.org/licenses/by/3.0 application/pdf European Geosciences Union / Copernicus Copernicus |
| spellingShingle | Velasco, Erik Pressley, S. Grivicke, R. Allwine, E. Coons, T. Foster, W. Jobson, T. Westberg, H. Ramos, R. Hernandez, F. Molina, Luisa Tan Lamb, B. K. Eddy covariance flux measurements of pollutant gases in urban Mexico City |
| title | Eddy covariance flux measurements of pollutant gases in urban Mexico City |
| title_full | Eddy covariance flux measurements of pollutant gases in urban Mexico City |
| title_fullStr | Eddy covariance flux measurements of pollutant gases in urban Mexico City |
| title_full_unstemmed | Eddy covariance flux measurements of pollutant gases in urban Mexico City |
| title_short | Eddy covariance flux measurements of pollutant gases in urban Mexico City |
| title_sort | eddy covariance flux measurements of pollutant gases in urban mexico city |
| url | http://hdl.handle.net/1721.1/65593 https://orcid.org/0000-0002-3596-5334 |
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