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Ključne besede: PM10, black carbon, supervised machine learning
Objavljeno v RUNG: 12.03.2025; Ogledov: 504; Prenosov: 5
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Opis: Recent studies show that combining data with different time resolutions results in more detailed and likely more accurate source apportionment (SA) (Hopke et al., 2020; Manousakas et al., 2022; Via et al., 2023). Despite the advantages, SA studies, combining 24-hour filters and highly time-resolved analyses, are limited. This research aims to compare on- and off-line SA results in a pre-Alpine valley with a variety of sources. A comprehensive SA study of the local and regional PM sources and their size-segregated elemental fraction will be presented. PM10 was sampled daily on quartz filters from November 2020 to November 2021 and analyzed for a large array of chemical species. Equivalent black carbon (eBC) measurements were taken with the Aethalometer AE33. Hourly elemental PM10 and PM2.5 composition was measured in parallel with two Xact 625i from February until May 2021. Positive Matrix Factorization (PMF) was used to determine the sources of PM10 (off-line PMF) with 24-hour time resolution, and of the elemental fraction of PM (on-line PMF) with 1-hour time resolution for the overlapping time period. For off-line PMF, chemical species together with the source-specific eBC (Sandradewi et al., 2008) were used. For on-line PMF, two analyses were performed on the elemental composition: using PM10, and using a combination of PM2.5 and PMcoarse (PM10-PM2.5). The final off-line PM10 PMF results were compared to on-line elemental PM PMF and assessed accordingly. A combination of the different PMF models with various instrument data resulted in improved SA in terms of the number of identified sources and their uncertainties. The off-line PMF resolved ten PM10 sources (Fig. 1, left), while the on-line elemental PM10 and the combined elemental PM2.5+coarse PMF recognized 6 and 7 factors, respectively (Fig. 1, right). Due to large number of samples, we were able to separate between the sources with strong seasonality and sources featuring stability throughout the year. The study disclosed two rarely encountered factors, i.e., chloride-rich (chlorine-rich in case of on-line PMF) and cement dust. Introduction of source-specific eBC in the off-line PMF model resulted in more stable factor solutions.The high-resolution on-line PMF enabled us to distinguish between regional and local sources (see mineral dust factors). Furthermore, the size-segregated on-line PMF provided more speciated sources (traffic separation into heavy-duty and light-duty vehicles). A very good regression (R2 > 0.7, slopes = 0.05–0.35, p < 0.001) between the compared off-line PM10 and on-line elemental PM10 (daily averages) factors’ concentrations confirmed the adequacy of the SAs. Further work involves a direct comparison of fractions of the elements in the sources’ chemical profiles. The study clearly shows the advantages and limitations of the different PMF models. A combined use of various SA approaches appears to be a promising way towards a comprehensive analysis of the PM sources in complex environments.
Ključne besede: positive matrix factorization, PM10 composition, metals, Xact, HVS digitel
Objavljeno v RUNG: 24.01.2025; Ogledov: 736; Prenosov: 7
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Opis: Les je v Sloveniji tradicionalno pomemben obnovljiv vir za ogrevanje v gospodinjstvih. Pri tem nastajajo delci, ki imajo negativen vpliv na zdravje. Z namenom določitve vpliva izgorevanja lesne biomase na raven onesnaženja z delci smo na več lokacijah v obdobju med 2016 in 2021 izvedli vzorčenje delcev PM10 in njihovo kemijsko analizo. Analiza je bila usmerjene v parametre povezane z izgorevanje lesne biomase: levoglukozan, manozan, galaktozan, organski in elementarni ogljik, kalij in benzo [a] piren. V obdobju med 2016 in 2021 so bile v januarju in februarju najvišje koncentracije izmerjene v letu 2017, najnižje pa v letu 2021. Razlike so povezane predvsem z različnimi meteorološkimi razmerami. Koncentracije delcev PM10, kot tudi koncentracije in deleži levoglukozana, kalija in benzo [a] pirena so bile v zimskih mesecih višje, kot v poletnem obdobju. Izjema sta le organski in elementarni ogljik, pri katerih je koncentracija v zimskem času višja, kot v poletnem, njuna deleža v delcih PM10 pa se preko leta bistveno ne spreminjata. Na podlagi razmerja med levoglukozanom in manozanom smo ugotovili, da se v Sloveniji za ogrevanje uporablja tako mehek, kot trd les. Delež delcev, ki jih lahko pripišemo izgorevanju lesne biomase je bil v januarju in februarju v obravnavnem obdobju visok – najvišji je bil v Novem mestu (52 % ± 5 %), najnižji pa v Mariboru (21 % ± 6 %).
Ključne besede: delci PM10, levoglukozan, manozan, izgorevanje lesne biomase, raven onesnaženja z delci, magistrske naloge
Objavljeno v RUNG: 26.09.2024; Ogledov: 1286; Prenosov: 12
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Opis: 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.
Ključne besede: Sarajevo, Bosnia and Herzegovina, urban air pollution, PM10, PM2.5
Objavljeno v RUNG: 03.09.2021; Ogledov: 3774; Prenosov: 51
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Opis: This paper examines atmospheric concentrations of particulate matter with an aerodynamic diameter smaller than 10 μm (PM10) and related particle-phase toxic heavy metals Cd, Ni, and Pb during domestic heating seasons from 2010 to 2019 in Sarajevo, Bosnia and Herzegovina. In total, 242 daily PM10 samples were collected using medium and high volume air samplers. The mean daily PM10 mass concentration for all measurements is 75.16 μg/m3 (with the range of 28.77–149.00 μg/m3). Variation of ambient PM10 was observed throughout the study in different years. Hourly values for PM10 measurements during two heating seasons are also presented. Metal concentrations in PM10 were analyzed by electrothermal atomic absorption spectrometry (ETAAS). Quantities of atmospheric mass concentrations of studied trace metals were observed in the following order: Pb > Ni > Cd. The mean concentrations of metals varied with Pb showing the highest concentration (ranging from 1.38 to 234.00 ng/m3), Ni ranging from 0.87 to 42.43 ng/m3, and Cd showing the lowest concentration ranging from 0.26 to 10.09 ng/m3. The concentration of Pb and Cd in PM10 was strongly correlated, suggesting a common source or dependence of these metals in PM10 in Sarajevo. Bioaccessibility of metals in the synthetic gastric juice was also estimated. The quantities of average bioaccessible metal fractions in PM10 samples showed the following trend: Cd > Pb > Ni. The health risk assessment shows that the population of Sarajevo is at increased lifetime risk of experiencing cancer because of exposure to these Cd concentrations in PM10. In addition, parallel PM10 sampling on two samplers showed that obtained results are highly comparable.
Ključne besede: air, PM10, heavy metals, Sarajevo
Objavljeno v RUNG: 09.04.2021; Ogledov: 3580; Prenosov: 0
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