Research on Volatile Organic Compounds in the Mexico City Metropolitan Area (MCMA) in two campaigns collected in the Winter-2011 and Spring-2012
Abstract
Because of the importance of information on the concentration and speciation of Volatile Organic Compounds (VOC) in the atmosphere for the development of regulatory programs or emission control, is necessary to determine the type and the concentrations of reactive and toxic VOC in atmospheric air. The aim of this study is to determine the speciation and quantification of VOC in the atmospheric air of the Mexico City Metropolitan Area (MCMA), from samples obtained in November-December 2011 (cold-dry) and March-April (warm-dry). This study presents the results of characterization of VOC in ambient air in the MCMA conducted during 2011-2012. Sampling of VOC was done in two sampling campaigns: from November 17th to December 11th, 2011, and March 1st to April 6th, 2012 through collection of ambient air each six days in six liters stainless steel SUMMA canisters of 24 hours integrated samples, in three sites (Merced: commercial area with vehicular sources, Pedregal: residential area with vehicular sources and San Agustin: industrial sources with heavy traffic), in the MCMA. The analysis of samples was carried out with two chromatographic systems: 1) method equivalent to the EPA's Method TO-14, and 2) GC/MSD coupled to a preconcentrator ENTECH, for the analysis of the compounds listed in EPA method TO15. It was investigated the concentration of 111 volatile organic compounds, (ozone precursors and toxic compounds). It was found that concentrations of 23 species, constitute 80% of the total VOC concentration tested: ethane, propane, isobutane, n-butane, n-pentane, n-hexane, isopentane, methylcyclopentane, ethylene, propylene, acetylene, benzene, toluene, ethylbenzene, m/p-xylene, o-xylene, 1,2,4-trimethylbenzene, ethyl and isopropyl alcohols, acetone, 2-butanone, MTBE and ethyl acetate. Both in 2011 and 2012, the highest concentrations measured in the three sites were for compounds associated with the combustion of LPG gas: propane, n-butane. The highest concentrations of 25.2±14.5 ppbV and 16.6±9 ppbV for butane and propane respectively, was achieved in Merced in 2011 and 14.7±3.5 ppbV and 28.4±6.7 ppbV for the same compounds, in San Agustin in 2012). In the case of vehicular emissions, in both campaigns, 2011 and 2012, Merced showed the highest levels: 12.3±4.8 ppbV, 2.7±1.1 ppbV and 4.3±3.3 ppbV for toluene, benzene and MTBE respectively in 2011 and 9.48±6.5 ppbV, 1.5±0.9 ppbV and 2.4±1.0 ppbV for the same compounds in 2012. The compounds which comes from industrial emissions, have the lowest average concentrations in all stations. The VOCs measurement in atmospheric air, allowed determinate that the main source of VOC in the three studied sites of the MCMA are emissions of LPG gas and vehicular emissions. The highest concentrations were found during the cold-dry period in 2011. These data are consistent with continuous measurements determined in the southeastern MCMA during 2000-2007.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSM.A42A..02M
- Keywords:
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- 0345 ATMOSPHERIC COMPOSITION AND STRUCTURE / Pollution: urban and regional