Journal article
Particulate polycyclic aromatic hydrocarbon spatial variability and aging in Mexico City
Atmospheric chemistry and physics discussions, Vol.7(6), pp.15693-15721
09 Nov 2007
Abstract
As part of the Megacities Initiative: Local and Global Research Observations (MILAGRO) study in the Mexico City Metropolitan Area in March 2006, we measured particulate polycyclic aromatic hydrocarbons (PAHs) and other gaseous species and particulate properties at six locations throughout the city. The measurements were intended to support the following objectives: to describe spatial and temporal patterns in PAH concentrations, to gain insight into sources and transformations of PAHs, and to quantify the relationships between PAHs and other pollutants. Total particulate PAHs at the Instituto Mexicano del Petróleo (T0 supersite) located near downtown averaged 50 ng m?3, and aerosol active surface area averaged 80 mm2 m?3. PAHs were also measured on board the Aerodyne Mobile Laboratory, which visited six sites encompassing a mixture of different land uses and a range of ages of air parcels transported from the city core. Weak intersite correlations suggest that local sources are important and variable and that exposure to PAHs cannot be represented by a single regional-scale value. The relationships between PAHs and other pollutants suggest that a variety of sources and ages of particles are present. Among carbon monoxide, nitrogen oxides (NOx), and carbon dioxide, particulate PAHs are most strongly correlated with NOx. Mexico City's PAH-to-black carbon mass ratio of 0.01 is similar to that found on a freeway loop in the Los Angeles area and approximately 8?30 times higher than that found in other cities. Ratios also indicate that primary combustion particles are rapidly coated by secondary aerosol in Mexico City. If so, the lifetime of PAHs may be prolonged if the coating protects them against photodegradation or heterogeneous reactions.
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Details
- Title
- Particulate polycyclic aromatic hydrocarbon spatial variability and aging in Mexico City
- Creators
- D. A. Thornhill - Virginia TechS. C. Herndon - Aerodyne ResearchT. B. Onasch - Aerodyne ResearchE. C. Wood - Drexel University, ChemistryM. Zavala - Molina Center for Energy and the EnvironmentL. T. Molina - Molina Center for Energy and the EnvironmentJ. S. Gaffney - University of Arkansas at Little RockN. A. Marley - University of Arkansas at Little RockL. C. Marr - Department of Civil and Environmental Engineering
- Publication Details
- Atmospheric chemistry and physics discussions, Vol.7(6), pp.15693-15721
- Publisher
- European Geosciences Union
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemistry
- Identifiers
- 991020902867304721