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Opis: Abstract. Black carbon (BC) is recognized as the most important warming agent among atmospheric aerosol particles. The absorption efficiency of pure BC is rather well-known, nevertheless the mixing of BC with other aerosol particles can enhance the BC light absorption efficiency, thus directly affecting Earth's radiative balance. The effects on climate of the BC absorption enhancement due to the mixing with these aerosols are not yet well constrained because these effects depend on the availability of material for mixing with BC, thus creating regional variations. Here we present the mass absorption cross-section (MAC) and absorption enhancement of BC particles (Eabs), at different wavelengths (from 370 to 880 nm for online measurements and at 637 nm for offline measurements) measured at two sites in the western Mediterranean, namely Barcelona (BCN; urban background) and Montseny (MSY; regional background). The Eabs values ranged between 1.24 and 1.51 at the urban station, depending on the season and wavelength used as well as on the pure BC MAC used as a reference. The largest contribution to Eabs was due to the internal mixing of BC particles with other aerosol compounds, on average between a 91 % and a 100 % at 370 and 880 nm, respectively. Additionally, 14.5 % and 4.6 % of the total enhancement at the short ultraviolet (UV) wavelength (370 nm) was due to externally mixed brown carbon (BrC) particles during the cold and the warm period, respectively. On average, at the MSY station, a higher Eabs value was observed (1.83 at 637 nm) compared to BCN (1.37 at 637 nm), which was associated with the higher fraction of organic aerosols (OA) available for BC coating at the regional station, as denoted by the higher organic carbon to elemental carbon (OC:EC) ratio observed at MSY compared to BCN. At both BCN and MSY, Eabs showed an exponential increase with the amount of non-refractory (NR) material available for coating (RNR-PM). The Eabs at 637 nm at the MSY regional station reached values up to 3 during episodes with high RNR-PM, whereas in BCN, Eabs kept values lower than 2 due to the lower relative amount of coating materials measured at BCN compared to MSY. The main sources of OA influencing Eabs throughout the year were hydrocarbon OA (HOA) and cooking-related OA (COA), i.e. primary OA (POA) from traffic and cooking emissions, respectively, at both 370 and 880 nm. At the short UV wavelength (370 nm), a strong contribution to Eabs from biomass burning OA (BBOA) and less oxidized oxygenated OA (LO-OOA) sources was observed in the colder period. Moreover, we found an increase of Eabs with the ageing state of the particles, especially during the colder period. This increase of Eabs with particle ageing was associated with a larger relative amount of secondary OA (SOA) compared to POA. The availability of a long dataset at both stations from offline measurements enabled a decade-long trend analysis of Eabs at 637 nm, that showed statistically significant (s.s.) positive trends of Eabs during the warmer months at the MSY station. This s.s. positive trend in MSY mirrored the observed increase of the OC:EC ratio over time. Moreover, in BCN during the COVID-19 lockdown period in spring 2020 we observed a sharp increase of Eabs due to the observed sharp increase of the OC:EC ratio. Our results show similar values of Eabs to those found in the literature for similar background stations.
Ključne besede: black carbomn, coating, organic aerosol, light absorption
Objavljeno v RUNG: 10.05.2024; Ogledov: 119; Prenosov: 2
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Opis: Particularly during the cold weather season, countries of the Southeast Europe are experiencing some of the poorest air quality in the world due to the extensive use of solid fuels and old vehicle fleets. The city of Sarajevo is the capital of Bosnia and Herzegovina (BiH) situated within a basin surrounded by mountains. In the winter months (domestic heating season), topography and meteorology cause the pollutants to be trapped within the city basin. Countries of the Southeast Europe lack state-of-the-art atmospheric sciences research and access to sophisticated instrumentation and methodology, despite high levels of ambient pollution and position within the European Union (EU) borders, making it imperative to understand the emission sources, processing and the adverse health effects of atmospheric aerosol pollution.                This presentation will highlight the field measurements in Central and Southeast Europe during the Sarajevo Canton Winter Field Campaign 2017-2018 (SAFICA) and Sarajevo Aerosol Experiment 2022-2023 (SAAERO) projects, centered at the Sarajevo Bjelave supersite. Both projects were envisioned to produce crucial, not previously available information about aerosol emission sources and atmospheric transformations through a combination of online field and offline laboratory measurements. Online measurements during a) SAFICA and b) SAAERO included, a) black carbon, particle number and size distribution, and b) carbonaceous species, elemental composition and bulk chemical composition. SAAERO online measurements also included stationary and mobile measurements of gas- and particle-phase species on board the mobile laboratory in Sarajevo and Zenica, BiH, as well as in Ljubljana, Slovenia and Zagreb, Croatia. Finally, extended SAAERO project included measurements of black carbon at three additional urban centers: Ljubljana, Zagreb, and Belgrade, Serbia, enabling the first comparison of urban air quality in Central and Southeast Europe between two EU and two non-EU capitals. During both projects, laboratory aerosol analyses determined aerosol bulk chemical composition, selected elements (Huremović et al., 2020; Žero et al., 2022) and molecular species (Pehnec et al., 2020). Aerosol chemical composition determined by aerosol mass spectrometry was further analyzed by Positive Matrix Factorization to separate organic aerosol into subtypes characteristic of specific sources and atmospheric processes. Aerosol oxidative potential was also determined to evaluate aerosol ability to generate reactive oxygen species. Sarajevo and Belgrade have high ambient loadings of aerosol and black carbon, indicative of strong and diverse combustion sources and a major public health hazard. Finally, aerosol surface concentrations will be discussed in the context of European air quality. We thank Jasminka Džepina, Magee Scientific/Aerosol, TSI and Aerodyne for support. We acknowledge the contribution of the COST Action CA16109 COLOSSAL and SEE Change Net. KDž and ASHP acknowledge the grant by the Swiss NSF (Scientific Exchanges IZSEZ0_189495), KDž, GM and ASHP European Commission SAAERO grant (EU H2020 MSCA-IF 2020 #101028909), GM Slovenian ARIS grant (P1-0385), SF Croatian HRZZ grant (BiREADI IP-2018-01-3105), and AG, MR, MI, BA and IBJ Slovenian ARIS grant (L1-4386). Pehnec, G., et al., Sci. Tot. Environ., 734, 139414, 2020. Huremović, J., et al., Air Qual. Atmos. Health, 13, 965–976, 2020. Žero, S., Žužul, S., et al., Environ. Sci. Technol., 56, 7052−7062, 2022.
Ključne besede: air pollution, sources of pollution, PMF
Objavljeno v RUNG: 18.03.2024; Ogledov: 409; Prenosov: 2
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Opis: The present invention belongs to the field of methods and devices for analysing materials by determining their chemical or physical properties by the use of thermos-optical means. The invention relates to a device and a method for complete carbonaceous aerosol analysis in real time, which is essentially a system combining two different instruments, wherein the first instrument measures total carbon (TC) using flash heating of collected aerosol samples and generation of CO2, while the second instrument performs an optical attenuation analysis at 7 wavelengths from near UV (370 nm) to near IR range (950 nm) in order to characterize a Black Carbon (BC/EC) aerosols accumulated on a glass-fiber/PTFE filter tape. The device, i.e., the system of said instruments, collects and processes collected data of both instruments, wherein said processing may be performed by any of the instruments or by a separate processing means, computer or computer application.
Ključne besede: carbonaceous aerosol, black carbon, total carbon, brown carbon
Objavljeno v RUNG: 02.02.2024; Ogledov: 503; Prenosov: 8
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Opis: Cataphora (also known as backward anaphora) is a type of pronominals that prcede their antecedents elinearly. Previous research on processing cataphora has explored the idea that cataphoric pronouns trigger a forward-looking active search for an antecedent to establish a coreference relation similar to a filler-gap dependency between a fronted wh-phrase and its base-generated syntactic position (Cowart & Cairns 1987). Van Gompel & Liversedge (2003) have shown that in an active search, the parser establishes a cataphoric coreference before considering pronominal phi-features. This results in a gender mismatch effect: sentences with incongruent incoming NP antecedents were more difficult to read than their congruent counterparts, as evidenced by slower reading times and eye movement regressions. In this paper, we report the results of a self-paced reading experiment in which the active search hypothesis is further tested by examining online cataphora resolution with respect to the number feature in Slovenian, a pro-drop language with a rich nominal and verbal morphology.
Ključne besede: cataphora, feature mismatch effect, forward-looking active search, self-paced reading, Slovenian, psycholinguistics
Objavljeno v RUNG: 16.01.2024; Ogledov: 580; Prenosov: 8
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Ključne besede: sentence comprehension, heritage speakers, bilingualism, Slovenian, Italian
Objavljeno v RUNG: 03.10.2023; Ogledov: 758; Prenosov: 7
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