Emissions of volatile organic compounds inferred from airborne flux measurements over a megacity

AMS Citation:
Karl, T., E. C. Apel, A. Hodzic, D. D. Riemer, D. R. Blake, and C. Wiedinmyer, 2009: Emissions of volatile organic compounds inferred from airborne flux measurements over a megacity. Atmospheric Chemistry and Physics, 9, 271-285, doi:10.5194/acp-9-271-2009.
Date:2009-01-14
Resource Type:article
Title:Emissions of volatile organic compounds inferred from airborne flux measurements over a megacity
Abstract: Toluene and benzene are used for assessing the ability to measure disjunct eddy covariance (DEC) fluxes of Volatile Organic Compounds (VOC) using Proton Transfer Reaction Mass Spectrometry (PTR-MS) on aircraft. Statistically significant correlation between vertical wind speed and mixing ratios suggests that airborne VOC eddy covariance (EC) flux measurements using PTR-MS are feasible. City-median midday toluene and benzene fluxes are calculated to be on the order of 14.1±4.0 mg/m²/h and 4.7±2.3 mg/m²/h, respectively. For comparison the adjusted CAM2004 emission inventory estimates toluene fluxes of 10 mg/m²/h along the footprint of the flight-track. Wavelet analysis of instantaneous toluene and benzene measurements during city overpasses is tested as a tool to assess surface emission heterogeneity. High toluene to benzene flux ratios above an industrial district (e.g. 10-15 g/g) including the International airport (e.g. 3-5 g/g) and a mean flux (concentration) ratio of 3.2±0.5 g/g (3.9±0.3 g/g) across Mexico City indicate that evaporative fuel and industrial emissions play an important role for the prevalence of aromatic compounds. Based on a tracer model, which was constrained by BTEX (BTEX- Benzene/Toluene/Ethylbenzene/m, p, o-Xylenes) compound concentration ratios, the fuel marker methyl-tertiary-butyl-ether (MTBE) and the biomass burning marker acetonitrile (CH₃CN), we show that a combination of industrial, evaporative fuel, and exhaust emissions account for >87% of all BTEX sources. Our observations suggest that biomass burning emissions play a minor role for the abundance of BTEX compounds in the MCMA (2-13%).
Peer Review:Refereed
Copyright Information:Copyright Authors 2009. This work is distributed under the Creative Commons Attribution 3.0 License
OpenSky citable URL: ark:/85065/d7qf8tx6
Publisher's Version: 10.5194/acp-9-271-2009
Author(s):
  • Thomas Karl - NCAR/UCAR
  • Eric Apel - NCAR/UCAR
  • Alma Hodzic - NCAR/UCAR
  • D. Riemer
  • D. Blake
  • Christine Wiedinmyer - NCAR/UCAR
  • Random Profile

    ADMIN ASSISTANT III

    Recent & Upcoming Visitors