Characterization of aerosol chemical composition with aerosol mass spectrometry in Central Europe: an overview

Abstract

Real-time measurements of non-refractory submicron aerosols (NR-PM<sub>1</sub>) were conducted within the greater Alpine region (Switzerland, Germany, Austria, France and Liechtenstein) during several week-long field campaigns in 2002–2009. This region represents one of the most important economic and recreational spaces in Europe. A large variety of sites was covered including urban backgrounds, motorways, rural, remote, and high-alpine stations, and also mobile on-road measurements were performed. Inorganic and organic aerosol (OA) fractions were determined by means of aerosol mass spectrometry (AMS). The data originating from 13 different field campaigns and the combined data have been utilized for providing an improved temporal and spatial data coverage. <br><br> The average mass concentration of NR-PM<sub>1</sub> for the different campaigns typically ranged between 10 and 30 μg m<sup>−3</sup>. Overall, the organic portion was most abundant, ranging from 36% to 81% of NR-PM<sub>1</sub>. Other main constituents comprised ammonium (5–15%), nitrate (8–36%), sulfate (3–26%), and chloride (0–5%). These latter anions were, on average, fully neutralized by ammonium. As a major result, time of the year (winter vs. summer) and location of the site (Alpine valleys vs. Plateau) could largely explain the variability in aerosol chemical composition for the different campaigns and were found to be better descriptors for aerosol composition than the type of site (urban, rural etc.). Thus, a reassessment of classifications of measurements sites might be considered in the future, possibly also for other regions of the world. <br><br> The OA data was further analyzed using positive matrix factorization (PMF) and the multi-linear engine ME (factor analysis) separating the total OA into its underlying components, such as oxygenated (mostly secondary) organic aerosol (OOA), hydrocarbon-like and freshly emitted organic aerosol (HOA), as well as OA from biomass burning (BBOA). OOA was ubiquitous, ranged between 36% and 94% of OA, and could be separated into a low-volatility and a semi-volatile fraction (LV-OOA and SV-OOA) for all summer campaigns at low altitude sites. Wood combustion (BBOA) accounted for a considerable fraction during wintertime (17–49% OA), particularly in narrow Alpine valleys BBOA was often the most abundant OA component. HOA/OA ratios were comparatively low for all campaigns (6–16%) with the exception of on-road, mobile measurements (23%) in the Rhine Valley. The abundance of the aerosol components and the retrievability of SV-OOA and LV-OOA are discussed in the light of atmospheric chemistry and physics

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

“…Crippa et al (2014) reported OOA/NH + 4 ratios for 25 sites, with an average of 2.0 (0.3 for the site with the lowest ratio and 7.3 for the one with the highest). Lanz et al (2010) reported values of 5.6 and 1.5 for Zurich in July 2005 and January 2006, respectively. The values for Zurich during the period analyzed here are 5.1 (offline, first and third quartiles of 3.0 and 11.50) and 5.1 (online, first and third quartiles of 3.0 and 10.5).…”

“…Application of advanced factor-based receptor models such as positive matrix factorization (PMF, Paatero and Tapper, 1994) to these spectra has been proven effective in apportioning OA into different factors (e.g. Lanz et al, 2007Lanz et al, , 2010Jimenez et al, 2009;Zhang et al, 2011;Ng et al, 2010;Crippa et al, 2014). These factors are subsequently related to primary sources like biomass burning (BBOA), traffic (HOA), and cooking (COA), as well as oxygenated organic aerosol (OOA), which is often attributed to SOA.…”

Elemental composition of ambient aerosols measured with high temporal resolution using an online XRF spectrometer

“…Other local activities include industrial buildings approximately 500 m to the north-west (logistics businesses) and a metal processing company to the south-east across the freeway. The site is well documented with respect to gas-phase traffic emissions, PM number concentrations, and particulate elemental carbon (EC; Hueglin et al, 2006), but an in-depth local source apportionment has not been realized so far except for organic aerosols measured in May 2005 (Lanz et al, 2010).…”

“…A small field campaign was organized at a monitoring station of the Swiss Air Pollution Monitoring Network (NABEL), where qualitycontrolled air pollution measurements are performed continuously. The NABEL network provided the reference for previous data intercomparisons (Hueglin et al, 2005;Lanz et al, 2010), as well as for the intercomparisons of this study. Comparisons between SR-XRF and filter samples analysed with ICP-OES and ICP-MS have been performed previously .…”

Atmospheric electricity as a proxy for air quality: Relationship between potential gradient and pollutant gases in an urban environment

“…In the urban context, most secondary PM occur as sulphates and nitrates formed from reactions involving SO 2 and NO x , with typical annual mean values between 10-40 µgm -3 (black smoke method) or 50-150 µgm -3 (gravimetric method) (Shah et al, 1997). At the sub-micron fraction (PM 1 ), there is often a significant contribution from secondary organic aerosol (SOA) as highlighted by Lanz et al (2010).…”