Assessment of air pollution origin based on year-long parallel measurement of PM2.5 and PM10 at two suburban sites in Prague, Czech Republic

Jaroslav Schwarz; Petra Pokorná; Štěpán Rychlík; Hana Škáchová; Ondřej Vlček; Jiří Smolík; Vladimír Ždímal; Iva Hůnová

doi:10.1016/j.scitotenv.2019.01.426

Assessment of air pollution origin based on year-long parallel measurement of PM_2.5 and PM₁₀ at two suburban sites in Prague, Czech Republic

Sci Total Environ. 2019 May 10:664:1107-1116. doi: 10.1016/j.scitotenv.2019.01.426. Epub 2019 Feb 1.

Authors

Jaroslav Schwarz¹, Petra Pokorná², Štěpán Rychlík³, Hana Škáchová³, Ondřej Vlček³, Jiří Smolík¹, Vladimír Ždímal¹, Iva Hůnová³

Affiliations

¹ Department of Aerosol Chemistry and Physics, Institute of Chemical Process Fundamentals of the Czech Academy of Sciences, Rozvojová 2/135, 165 02 Prague 6, Czech Republic.
² Department of Aerosol Chemistry and Physics, Institute of Chemical Process Fundamentals of the Czech Academy of Sciences, Rozvojová 2/135, 165 02 Prague 6, Czech Republic. Electronic address: pokornap@icpf.cas.cz.
³ Czech Hydrometeorological Institute, Na Šabatce 17, 143 06 Prague 4, Czech Republic.

PMID: 30901784
DOI: 10.1016/j.scitotenv.2019.01.426

Abstract

From 2nd April 2008 to 28th March 2009, a total 248 daily samples of the PM_2.5 and PM₁₀ were collected every sixth day parallel at two suburban sites (Libuš and Suchdol) located at the two opposite sides (south and north, respectively) of Prague, Czech Republic. The PM_2.5 samples were analyzed for ions by ion chromatography (IC), organic and elemental carbon (OC and EC) by OC/EC analyzer and PM₁₀ samples also for 56 elements by inductively coupled plasma-mass spectrometry (ICP-MS). The average annual PM_2.5 and PM₁₀ was 24.4 ± 13.0 μg m^-3 and 26.7 ± 15.1 μg m^-3, respectively, in Prague-Libuš, and 25.1 ± 22.1 μg m^-3 and 27.1 ± 23.2 μg m^-3, respectively, in Prague-Suchdol. Since the species forming large part of the aerosol mass were strongly correlated (Spearman's rank correlation coefficient r_s > 0.80), the variability of PM_2.5 and PM₁₀ concentration was mainly driven by the local meteorology or regional and/or long range transport. PM₁₀ mass closure was calculated based on analytical results with the average percentage of recalculated mass of 77 ± 19% in Prague-Libuš and 86 ± 16% in Prague-Suchdol. The most abundant groups in PM₁₀ at both sites during the four seasons were OM (Prague-Libuš 34% and Prague-Suchdol 37%) and SIA (Prague-Libuš 30% and Prague-Suchdol 34%). The Positive Matrix Factorization (PMF) was applied to the chemical composition of PM₁₀ from both sites (124 samples) together to determine its sources. The nine factors were assigned as: mixed factor secondary sulphate and biomass burning, secondary sulphate, traffic, secondary nitrate, road dust, residential heating, aged sea salt, industry and mixed factor road salt along with aged sea salt. According to the polar plots and ventilation index (VI) east/west classification analysis the sources were separated based on origin to four categories local, urban agglomeration, regional and long range transport (LRT). The mixed source secondary sulphate and biomass burning, residential heating and industry were common sources of local origin at both sites. Prague-Suchdol was influenced by traffic related pollution from the urban agglomeration more than Prague-Libuš where the traffic and road dust/salt were of local origin. The regional pollution by secondary sulphates and nitrate was also relevant at both sites along with long range transport of sea salt from North Atlantic Ocean, Norwegian Sea and North Sea. The contribution of the local sources to PM₁₀ was significant mainly at Prague-Libuš site. However, the sources of regional origin were also important and influence of urban agglomeration pollution to PM₁₀ is not negligible as well.

Keywords: Mass closure; PM chemical composition; Positive Matrix Factorization; Regional pollution; Source apportionment; Ventilation index.