Abstract. Organic aerosols (OA) represent one of the major constituents of submicron particulate matter (PM1) and comprise a huge variety of compounds emitted by different sources. Three intensive measurement field campaigns to investigate the aerosol chemical composition all over Europe were carried out within the framework of the European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) and the intensive campaigns of European Monitoring and Evaluation Programme (EMEP) during 2008 (May–June and September–October) and 2009 (February–March). In this paper we focus on the identification of the main organic aerosol sources and we define a standardized methodology to perform source apportionment using positive matrix factorization (PMF) with the multilinear engine (ME-2) on Aerodyne aerosol mass spectrometer (AMS) data. Our source apportionment procedure is tested and applied on 25 data sets accounting for two urban, several rural and remote and two high altitude sites; therefore it is likely suitable for the treatment of AMS-related ambient data sets. For most of the sites, four organic components are retrieved, improving significantly previous source apportionment results where only a separation in primary and secondary OA sources was possible. Generally, our solutions include two primary OA sources, i.e. hydrocarbon-like OA (HOA) and biomass burning OA (BBOA) and two secondary OA components, i.e. semi-volatile oxygenated OA (SV-OOA) and low-volatility oxygenated OA (LV-OOA). For specific sites cooking-related (COA) and marine-related sources (MSA) are also separated. Finally, our work provides a large overview of organic aerosol sources in Europe and an interesting set of highly time resolved data for modeling purposes.

In many large cities of Europe standard air quality limit values of particulate matter (PM) are exceeded. Emissions from road traffic and biomass burning are frequently reported to be the major causes. As a consequence of these exceedances a large number of air quality plans, most of them focusing on traffic emissions reductions, have been implemented in the last decade. In spite of this implementation, a number of cities did not record a decrease of PM levels. Thus, is the efficiency of air quality plans overestimated? Do the road traffic emissions contribute less than expected to ambient air PM levels in urban areas? Or do we need a more specific metric to evaluate the impact of the above emissions on the levels of urban aerosols? This study shows the results of the interpretation of the 2009 variability of levels of PM, Black Carbon (BC), aerosol number concentration (N) and a number of gaseous pollutants in seven selected urban areas covering road traffic, urban background, urban-industrial, and urban-shipping environments from southern, central and northern Europe. The results showed that variations of PM and N levels do not always reflect the variation of the impact of road traffic emissions on urban aerosols. However, BC levels vary proportionally with those of traffic related gaseous pollutants, such as CO, NO2 and NO. Due to this high correlation, one may suppose that monitoring the levels of these gaseous pollutants would be enough to extrapolate exposure to traffic-derived BC levels. However, the BC/CO, BC/NO2 and BC/NO ratios vary widely among the cities studied, as a function of distance to traffic emissions, vehicle fleet composition and the influence of other emission sources such as biomass burning. Thus, levels of BC should be measured at air quality monitoring sites. During morning traffic rush hours, a narrow variation in the N/BC ratio was evidenced, but a wide variation of this ratio was determined for the noon period. Although in central and northern Europe N and BC levels tend to vary simultaneously, not only during the traffic rush hours but also during the whole day, in urban background stations in southern Europe maximum N levels coinciding with minimum BC levels are recorded at midday in all seasons. These N maxima recorded in southern European urban background environments are attributed to midday nucleation episodes occurring when gaseous pollutants are diluted and maximum insolation and O3 levels occur. The occurrence of SO2 peaks may also contribute to the occurrence of midday nucleation bursts in specific industrial or shipping-influenced areas, although at several central European sites similar levels of SO2 are recorded without yielding nucleation episodes. Accordingly, it is clearly evidenced that N variability in different European urban environments is not equally influenced by the same emission sources and atmospheric processes. We conclude that N variability does not always reflect the impact of road traffic on air quality, whereas BC is a more consistent tracer of such ...

Particle number concentration data have been collected on a very busy road in central London (Marylebone Road). Continuous size distributions from 15 nm to 10 μm diameter, collected over 21 days, were analyzed using positive matrix factorization which identified 10 factors, five of which were observed to make major contributions (greater than 8%) to either the total number or volume of particulate matter. The sources associated with each factor were identified from the size distribution, directional association, diurnal variation and their relationship to meteorological pollution and traffic volume variables. The factors related to the emissions on Marylebone Road accounted for 40.5% of particle volume and 71.9% of particle number. These comprised nucleation mode exhaust particles (3.6% of total volume and 27.4% of total number), solid mode exhaust particles (18.8% of total volume and 38.0% of total number), brake dust (13.7% of total volume and 1.7% of total number and resuspension (4.4% of total volume and 4.8% of total number). Another six factors were associated with the urban background accounting for 59.5% of total volume and 28.2% of total particle number count. The method is extremely successful at separating the components of on-road emissions including brake wear and resuspension.

[1] Using on-line High-Resolution Aerosol Mass Spectrometry, we report submicron organic marine aerosol plume concentrations peaking at 3.8 mg m − 3 . These concentrations are far greater than previously determined by off-line techniques and can exceed typical terrestrial concentrations of organic aerosol. The organic mass comprised 77% of the total submicron non-refractory mass and such plumes were associated with regions of high biological activity and moderately-high wind speeds over the N.E. Atlantic. High-resolution mass spectra analysis revealed a unique marine organic aerosol fingerprint, when compared to anthropogenic organic aerosol, and in particular, anthropogenic hydrocarbons. 37% hydrocarbon and 63% oxygenated hydrocarbon speciation was observed for the organic mass, indicating that at least 37% of the organic mass is produced via primary sea-spray. The hydrocarbon and oxygenated hydrocarbon species were highly correlated (r > 0.99) suggesting a significant, if not dominant, fraction of the oxygenated component is also likely to be sea-spray in origin.