Abstract
Abstract. The effect of a post-industrial megacity on local and regional air quality was assessed via a month-long field measurement campaign in the Paris metropolitan area during winter 2010. Here we present source apportionment results from three aerosol mass spectrometers and two aethalometers deployed at three measurement stations within the Paris region. Submicron aerosol composition is dominated by the organic fraction (30–36%) and nitrate (28–29%), with lower contributions from sulfate (14–16%), ammonium (12–14%) and black carbon (7–13%). Organic source apportionment was performed using positive matrix factorization, resulting in a set of organic factors corresponding both to primary emission sources and secondary production. The dominant primary sources are traffic (11–15% of organic mass), biomass burning (13–15%) and cooking (up to 35% during meal hours). Secondary organic aerosol contributes more than 50% to the total organic mass and includes a highly oxidized factor from indeterminate and/or diverse sources and a less oxidized factor related to wood burning emissions. Black carbon was apportioned to traffic and wood burning sources using a model based on wavelength-dependent light absorption of these two combustion sources. The time series of organic and black carbon factors from related sources were strongly correlated. The similarities in aerosol composition, total mass and temporal variation between the three sites suggest that particulate pollution in Paris is dominated by regional factors, and that the emissions from Paris itself have a relatively low impact on its surroundings.
Highlights
The last two centuries have seen the global rise of densely populated urban areas
An additional comparison was performed between biomass burning OA (BBOA) and levoglucosan concentrations from 12-h filters measurements obtained at the SIRTA and LHVP sites (R2 = 0.81 and R2 = 0.69, respectively), showing a high correlation with both the averaged positive matrix factorization (PMF) biomass burning and OOA2-BBOA components (Fig. 6)
To assess the effect of a post-industrial megacity on regional air quality, measurements of submicron aerosol composition were performed during winter 2010 in the Paris metropolitan area, including three stationary measurement sites and two mobile laboratories
Summary
The last two centuries have seen the global rise of densely populated urban areas. Megacities, defined as urban areas with a population of over 10 million people (Molina and Molina, 2004a), potentially serve as major sources of gas and particle emissions. Recent studies have investigated aerosol characteristics and behavior in the Paris region, including aethalometer measurements of wood burning emissions (Favez et al, 2009), source apportionment of volatile organic compounds (VOCs) during spring (Gaimoz et al, 2011) and the quantification of wintertime carbonaceous material and inorganic ions (Sciare et al, 2011). Our work complements these efforts by identifying the major aerosol sources in the Paris region, focusing on particle chemical speciation of the submicron fraction and OA source apportionment. Comparison of these two independent apportionment efforts helps to validate the results of each other and provides insight into the variations caused by regional versus local sources
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