Combination of Different Approaches to Infer Local or Regional Contributions to PM2.5 Burdens in Graz, Austria

Abstract

In early 2017 high particulate matter (PM) levels were observed across mid-Europe, including Austria. Here we characterize PM pollution in the city of Graz during January to March 2017, a period with substantial exceedances (34 days) of the European Union (EU) PM10 short time limit value. This study evaluates whether the observed exceedances can be attributed to the accumulation of pollutants emitted by local sources or to a larger scale pollution episode including transport. The analyses are based on the ratios of PM10 concentrations determined at an urban and background site, and the analyses of chemical composition of PM2.5 samples (i.e., water soluble ions, organic and elemental carbon, anhydro-sugars, humic-like substances, aluminum, and polycyclic aromatic hydrocarbons). Source apportionment was realized using a macro-tracer model. Overall, the combination of different approaches (PM10 ratios, chemical composition, and macro-tracer derived source apportionment) enabled a conclusive identification of time periods characterized by the accumulation of emissions from local sources or regional pollution episodes.

Organic tracers in fine and coarse aerosols at an urban Mediterranean site: contribution of biomass burning and biogenic emissions

“…This approach assumes a fixed emission ratio between a compound emitted from a certain source and a tracer from that source (Li et al 2021 ). Although the macro-tracer method has been extensively applied to estimate the contribution of BB to OC and PM concentrations (e.g., Galindo et al 2021 ; Kirchsteiger et al 2020 ; Stracquadanio et al 2019 ; Theodosi et al 2018 ), it is important to bear in mind that tracer emissions depend on multiple factors such as the type of biomass burned, moisture content, and combustion conditions, leading to uncertainty in the quantification of the real contribution of BB to aerosol levels. The protocol used to determine OC concentrations also adds uncertainty to estimates of the BB contribution since emission ratios are based on OC measurements.…”

Fine Micro- and Nanoplastics Particles (Pm2.5) in Urban Air and Their Relation to Polycyclic Aromatic Hydrocarbons

“…This rather simple approach was used to have a first approximation to differentiate between local and regional sources during a period of high PM concentrations as explained in the prior section. Based on PM 10 concentrations determined at GDB and the background site Bockberg (BB), Kirchsteiger et al (2020) identified time periods affected by long range transport (i.e. days showing quite similar concentration between GDB and BB and mass ratios ≤1.5) and days dominated by an influence of local sources (mass ratio >2).…”

“…All measurements were done in duplicates. To derive organic matter (OM) a conversion factor of 1.5 was applied (OM = 1.5*OC) (Kirchsteiger et al, 2020).…”

“…The remaining PM 2.5 mass, which is not explicitly mentioned here, was mainly inorganic ions and mineral dust. A detailed chemical evaluation and source apportionment of samples representing this time period is presented elsewhere (Kirchsteiger et al, 2020). Focusing on organics, the contribution of UFMNP to OM reaches an average value of 1.7% and a maximum value of 4.5%.…”