Aerosol particle measurements at three stationary sites in the megacity of Paris during summer 2009: meteorology and air mass origin dominate aerosol particle composition and size distribution

Abstract

During July 2009, a one-month measurement campaign was performed in the megacity of Paris. Amongst other measurement platforms, three stationary sites distributed over an area of 40 km in diameter in the greater Paris region enabled a detailed characterization of the aerosol particle and gas phase. Simulation results from the FLEXPART dispersion model were used to distinguish between different types of air masses sampled. It was found that the origin of air masses had a large influence on measured mass concentrations of the secondary species particulate sulphate, nitrate, ammonium, and oxygenated organic aerosol measured with the Aerodyne aerosol mass spectrometer in the submicron particle size range: particularly high concentrations of these species (about 4 μg m<sup>−3</sup>, 2 μg m<sup>−3</sup>, 2 μg m<sup>−3</sup>, and 7 μg m<sup>−3</sup>, respectively) were measured when aged material was advected from continental Europe, while for air masses originating from the Atlantic, much lower mass concentrations of these species were observed (about 1 μg m<sup>−3</sup>, 0.2 μg m<sup>−3</sup>, 0.4 μg m<sup>−3</sup>, and 1–3 μg m<sup>−3</sup>, respectively). For the primary emission tracers hydrocarbon-like organic aerosol, black carbon, and NO<sub>x</sub> it was found that apart from diurnal source strength variations and proximity to emission sources, local meteorology had the largest influence on measured concentrations, with higher wind speeds leading to larger dilution and therefore smaller measured concentrations. Also the shape of particle size distributions was affected by wind speed and air mass origin. Quasi-Lagrangian measurements performed under connected flow conditions between the three stationary sites were used to estimate the influence of the Paris emission plume onto its surroundings, which was found to be rather small. Rough estimates for the impact of the Paris emission plume on the suburban areas can be inferred from these measurements: Volume mixing ratios of 1–14 ppb of NO<sub>x</sub>, and upper limits for mass concentrations of about 1.5 μg m<sup>−3</sup> of black carbon and of about 3 μg m<sup>−3</sup> of hydrocarbon-like organic aerosol can be deduced which originate from both, local emissions and the overall Paris emission plume. The secondary aerosol particle phase species were found to be not significantly influenced by the Paris megacity, indicating their regional origin. The submicron aerosol mass concentrations of particulate sulphate, nitrate, and ammonium measured during time periods when air masses were advected from eastern central Europe were found to be similar to what has been found from other measurement campaigns in Paris and south-central France for this type of air mass origin, indicating that the results presented here are also more gen...

Contributions of local and regional sources to fine PM in the megacity of Paris

“…In all, 70 % of the OA was found to be transported from regional sources during both summer and winter. Freutel et al (2013) found that the concentrations of secondary species such as oxygenated OA, nitrate and ammonium during the summer MEGAPOLI campaign were quite similar for the three measurement sites in Paris, indicating the dominance of regional transport. Significant levels of secondary species were transported to Paris when the corresponding air masses originated from continental Europe.…”

“…This underestimation of local sources (almost 0.2 µg m −3 for summer and winter) could be explained by the behavior of fresh POA. Both the measurement-based studies of Beekmann et al (2014) and Freutel et al (2013) found that almost 62 % of the OA in the center of Paris was HOA (Primary Organic Aerosol) and cooking OA and 38 % was oxygenated OA. The discrepancy between the measurements and the model can be explained by the cooking emissions which have not been included in the PMCAMx inventory used in this study.…”

Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

“…For this campaign, measurements of organic carbon (OC), elemental carbon (EC) , and the most common ions are available. Finally, we have also analyzed 12 filter samples collected in Paris during summer 2009 and winter 2010, where concomitant online HR-ToF-AMS PM 1 measurements are available (Crippa et al, 2013a, b, c;Freutel et al, 2013).…”

“…Consequently, current data sets are typically limited to few weeks and specific sites or measurements from mobile platforms . Recently, a robust, less expensive, Aerosol Chemical Speciation Monitor (ACSM, Ng et al, 2011b) and a time-of-flight aerosol chemical speciation monitor (ToF-ACSM, Fröhlich et al, 2013Fröhlich et al, , 2015 were developed to overcome some of these shortcomings. However, the low mass resolution of these instruments reduces their utility.…”

Quantitative single-particle analysis with the Aerodyne aerosol mass spectrometer: development of a new classification algorithm and its application to field data

“…Details about this campaign, the sampling of the C-ToF-AMS, and comparison to co-located measurements can be found in Freutel et al (2013). As presented in Freutel et al (2013), both total mass concentration time series and average ensemble volume size distributions measured by the AMS agree within about 10-20 % with respective measurements of colocated instruments. For this dataset, from 107 734 singleparticle events, 26 123 single-particle mass spectra could be retrieved after applying the criteria described above.…”