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Sarajevo Canton Winter Field Campaign 2018 (SAFICA): aerosol source apportionment and oxidative potential in a global hotspot

Nowadays, urban centres in countries of the Western Balkan (e.g., Bosnia and Herzegovina, B&H) are experiencing some of the poorest air quality worldwide due to the extensive use of solid fuels and an old vehicle fleet. Western Balkan countries lack state-of-the-science atmospheric research despite high levels of ambient pollution, making the efforts to understand the mechanisms of their air pollution imperative. Sarajevo, the capital of B&H, is situated in a basin surrounded by mountains. During the winter months, topography and meteorology cause significant pollution episodes. The Sarajevo Canton Winter Field Campaign 2018 (SAFICA) took place from Dec 04, 2017 to Mar 15, 2018 with online aerosol measurements and collection of daily, continuous filter PM10 samples for offline laboratory analyses. SAFICA aimed to give the first detailed characterization of the Western Balkans aerosol composition including organic aerosol (OA) to elucidate aerosol emission sources and atmospheric processing and to estimate the adverse health effects. PM10 samples (ntotal=180) were collected at four sites in the Sarajevo Canton: a) Bjelave and b) Pofalići (both urban background) ; c) Otoka (urban) ; d) Ivan Sedlo (remote). The urban sites were distributed along the city basin to study the pollutants’ urban evolution and the remote site was chosen to compare urban to background air masses. SAFICA PM10 samples underwent the following offline laboratory chemical analyses: 1) Bulk chemical composition of the total filter-collected water-soluble inorganic and OA by a high- resolution Aerodyne Aerosol Mass Spectrometer (AMS). The measured AMS OA spectra were further analysed by Positive Matrix Factorization (PMF) using the graphical user interface SoFi (Source Finder) to separate OA into subtypes characteristic for OA sources and atmospheric processes. 2) Organic and elemental carbon, water- soluble organic carbon, polycyclic aromatic hydrocarbons (11), levoglucosan, organic acids (16) and 14C total carbon content to evaluate OA chemical composition. 3) Major inorganic anions and cations to evaluate aerosol inorganic species. 4) Aerosol metal content determined by three techniques (AAS, ICP-MS and EESI). 5) Aerosol oxidative potential (OP) by two methods (AA and DTT) to evaluate the ability of particles to generate adverse health effects causing reactive oxygen species. SAFICA online measurements of black carbon (Aethalometer) and the particle number conc. (CPC and OPS) enabled the insights into the daily evolution of primary pollutants and an assessment of aerosol size and number distribution. The combined SAFICA results for field and lab measurements will be presented. Our results show that carbonaceous aerosols make ~2/3 of PM10 mass and the majority are oxygenated, water-soluble OA species with an average OM/OC = 1.9 (Fig.1). Absolute OP levels are very high compared to other sites globally. However, more work is needed to estimate the contributions of different aerosol sources and species to total aerosol OP. Urban air pollution crises in the Western Balkan will be put in the context of local, regional and global air quality. Finally, we will present the scientific questions opened by SAFICA and give suggestions for future studies. We thank Federal Hydrometeorological Institute of B&H, Magee Scientific/Aerosol and TSI for support. We acknowledge the contribution of the COST Action CA16109 COLOSSAL and SEE Change Net. KDz and ASHP acknowledge the grant by the Swiss NSF (Scientific Exchanges IZSEZ0_189495), GM the Slovenian Science foundation program P1-0385, and SF by the Croatian Science Foundation (BiREADI IP-2018-01-3105).

Sarajevo ; SAFICA ; Urban air pollution ; PM10 ; source apportionment

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