In large urban agglomerations, car traffic is one of the main sources of particulate matter. It consists of particulate matter directly generated in the process of incomplete liquid fuel burning in vehicle engine, secondary aerosols formed from exhaust gaseous pollutants (NO_x, SO₂) as well as products of tires, brake pads and pavement abrasion. Krakow is one of the cities in Europe with the highest concentrations of particulate matter. The article presents the results of combined elemental, chemical and isotopic analyses of particulate matter PM₁₀ at two contrasting urban environments during winter and summer seasons. Daily PM₁₀ samples were collected during the summer and winter seasons of 2018/2019 at two stations belonging to the network monitoring air quality in the city. Mean PM₁₀ concentrations at traffic-dominated stations were equal to 35 ± 7 µg/m³ and 76 ± 28 µg/m³ in summer and winter, respectively, to be compared with 25.6 ± 5.7 µg/m³ and 51 ± 25 µg/m³ in summer and winter, respectively, recorded at the urban background station. The source attribution of analyzed PM₁₀ samples was carried out using two modeling approaches: (i) The Positive Matrix Factorization (PMF) method for elemental and chemical composition (concentrations of elements, ions, as well as organic and elemental carbon in daily PM₁₀ samples), and (ii) Isotope Mass Balance (IMB) for 13C and 14C carbon isotope composition of carbonaceous fraction of PM₁₀. For PMF application, five sources of particulate matter were identified for each station: fossil fuel combustion, secondary inorganic aerosols, traffic exhaust, soil, and the fifth source which included road dust, industry, construction work. The IMB method allowed the partitioning of the total carbon reservoir of PM₁₀ into carbon originating from coal combustion, from biogenic sources (natural emissions and biomass burning) and from traffic. Both apportionment methods were applied together for the first time in the Krakow agglomeration and they gave consistent results.

It is well documented that Southern Poland is one of the most polluted areas in Europe due to the highest airborne concentrations of particulate matter (PM). Concentrations of fine particles are especially high in winter. Apart from detailed number concentrations, it is essential to accurately identify and quantify specific particulate pollution sources. Only a few Polish research centers are involved in such experiments—among them is Krakow research group. For the most part, research focuses on collecting 24-h average samples from stationary PM samplers at ambient monitoring sites and quantifying the specific elements and chemical constituents in PM. This approach includes modeling methods that can use the variability in physical and chemical PM characteristics as an input dataset to identify possible sources of the particles. The objective of this paper is to provide research results based on data collected from June 2018 to May 2019 from a single monitoring station at a central urban site. Careful comparison of data obtained prior to a 2019 law prohibiting solid fuel burning in the city of Krakow with data (2019–2020) when a regulation went into effect should indicate progress by noting lower PM levels. This work has shown that the method applied and Krakow results might be of interest to the broader community in regions of high PM concentration.

Two fractions of suspended particulate matter (PM1 and PM10) were collected on daily basis in the urban atmosphere of Krakow, southern Poland, during one-year period (April 2018 - April 2019). The following compounds were examined: elemental carbon (EC), organic carbon (OC), carbohydrates (among them levoglucosan – a recognized biomass tracer),  as well as ions (Li+, Na+, NH4+, K+, Mg2+, Ca2+, F-, Cl-, NO2-, Br-. NO32-, PO43-, SO42-). Thermal-optical analysis with a Sunset carbon analyzer, (Sunset Lab. Inc.) was used to obtain information about organic and elemental carbon concentration, while HPAE-PAD Dionex ICS 3000 system was employed to determine the concentration of 14 carbohydrates. Concentration of ions was analysed using isocratic ion chromatography on an ICS-1100 instrument (Thermo Scientific).Distinct seasonality of chemical composition of PM1 and PM10 fraction was observed. Levoglucosan concentration ranged from 0.01 ug/m3 to 0.90 ug/m3 (PM1 fraction) and from 0.01 to ug/m3 to 1.95 ug/m3 (PM10 fraction) during the analysed period. Arabitol and Mannitol were detected only in PM10 fraction and ranged from 0.01 ug/m3 and 0.02 ug/m3, during winter season and to 0.15 ug/m3 and 0.10 ug/m3, respectively, during summer season. Significant seasonal differences were also found for ion concentrations: from 0.49 μg/m3 (SO42-), 0.15 μg/m3 (NO3-) and 0.05 μg/m3 (NH4+) during summer season, to be compared with 11.16 μg/m3 (SO42-), 9.30 μg/m3 (NO3-), 9.25 μg/m3 (NH4+) for winter season. The concentration of organic and elemental carbon in PM10 fraction ranged from 2.0 μg/m3 to 48.9 μg/m3 (OC) and from 0.3 μg/m3 to 10.0 μg/m3 (EC), to be compared  with 1.4 μg/m3 to 18.1 μg/m3 (OC) and 0.2 μg/m3 to 4.4 μg/m3 (EC) for PM1 fraction. ACKNOWLEDGEMENTSThe presented work was funded by Polish National Science Centre (project No.  2019/33/N/ST10/02925) as well as COST Action COLOSSAL (CA16109) of EU. Work of AS and PF have been partly supported by the EU Project POWR.03.02.00-00-I004/16. Analytical infrastructure of AGH Center of Energy in Krakow was employed in analyses of selected ions.

Recent years have brought a significant increase in public awareness of the issue of poor air quality in Poland. It is understandable that this problem has a direct impact on the quality of life of citizens of this country. Over the last few decades a concern over the health effects associated with air pollution was growing, mainly due to their carcinogenic and mutagenic properties. Various actions initiated by non-governmental organizations forced the authorities to undertake certain measures aimed at improving the quality of air in Poland, which, in the reports of the European Environment Agency is listed as one of the most polluted countries in the entire European Union. A model example here is the Krakow agglomeration. The city, located in a basin extending in the Vistula valley, surrounded on three sides by hills, in the cold period of the year struggles with the problem of poor air quality (very high concentrations of particulate matter and benzo(a)pyrene).The objective of this research was better characterization of two major elements responsible for poor air quality in Krakow agglomeration: existing sources of pollution and  local meteorology during heating season (HS) and  non-heating season (NHS). Samples were collected with 24h resolution using Low-Vol samplers in Krakow (50°00'38.1"N 19°56'57.1"E, Kurdwanow, Malopolska, South Poland) from February 2014 to January 2015. Based on the results of polycyclic aromatic hydrocarbons, cations, anions, mercury, organic and elemental carbon analyzes of samples of particulate matter collected in the city’s atmosphere, sources have been identified and classified them from the most to the least significant ones. The modeling tool Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT), developed by NOAA’s Air Resources Laboratory, was used to investigate the possible trajectories of air pollutants.This research was partially financed by the AGH UST grant 16.16.210.476 subsidy of the Ministry of Science and Higher Education. PF and AS have been partly supported by the EU Project POWR.03.02.00-00-I004/16. The infrastructure of the AGH Center of Energy in Kraków was applied in order to determine the concentration of ions.