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Mass absorption cross-section of ambient black carbon aerosols
No full textAn accurate assessment of black carbon (BC) climate and health impacts requires knowledge of its mass absorption cross-section (MACBC) – a parameter linking optical and mass measurements. The mean MACBC for freshly emitted soot typically spans a narrow range of 8 ± 1 m2 g⁻1 at 550 nm1,2 but is modified by subsequent atmospheric aging. Determination of MACBC requires simultaneous measurements of aerosol light-absorption coefficient (βabs) and BC mass. Here, we compile 230 measured MACBC values from 80 atmospheric studies and explore the effects of sampling location, study duration, instrumentation, and measurement wavelength. The compiled data set shows a broad variability in MACBC values (a factor of about 200%). We conclude that this variability is attributable to a combination of the above-mentioned effects with additional instrumental uncertainties (e.g., cross-sensitivities and/or inadequate instrument calibration). The current state of knowledge does not support the use of simplistic generalizations or assumptions about MACBC in the atmosphere, motivating a recommendation to further improve and standardize measurement practices.
An accurate assessment of black carbon (BC) climate and health impacts requires knowledge of its mass absorption cross-section (MAC
BC
) – a parameter linking optical and mass measurements. The mean MAC
BC
for freshly emitted soot typically spans a narrow range of 8 ± 1 m
2
g⁻
1
at 550 nm
1,2
but is modified by subsequent atmospheric aging. Determination of MAC
BC
requires simultaneous measurements of aerosol light-absorption coefficient (
β
abs
) and BC mass. Here, we compile 230 measured MAC
BC
values from 80 atmospheric studies and explore the effects of sampling location, study duration, instrumentation, and measurement wavelength. The compiled data set shows a broad variability in MAC
BC
values (a factor of about 200%). We conclude that this variability is attributable to a combination of the above-mentioned effects with additional instrumental uncertainties (e.g., cross-sensitivities and/or inadequate instrument calibration). The current state of knowledge does not support the use of simplistic generalizations or assumptions about MAC
BC
in the atmosphere, motivating a recommendation to further improve and standardize measurement practices
Assessing the severe urban pollution crisis in Sarajevo, Bosnia and Herzegovina
No full textParticulate air pollution is the leading environmental risk factor, contributing substantially to global morbidity and mortality. In the Western Balkans, air quality during winter months is among the poorest observed in Europe. Nevertheless, detailed chemical characterization of air pollution in the region remains limited, although such information is essential for identifying emission sources and supporting effective mitigation strategies. Therefore, a mobile measurement campaign was conducted in Sarajevo (Bosnia and Herzegovina) in January 2023 as part of the SArajevo AEROsol Experiment (SAAERO). The spatial distribution and chemical composition of particle- and gas-phase pollutants were investigated using multiple high-resolution instruments. Organic aerosol (OA), as a key component, accounted for 59% of the total submicron particulate matter (PM1). Source apportionment of the OA using Positive Matrix Factorization (PMF) resolved five distinct sources: two solid fuel combustion sources (SFC1 and SFC2), traffic (HOA), cooking (COA), and oxygenated OA (OOA). While daytime variation across the city was limited, an east–west pollution gradient emerged during evening hours, largely driven by SFC. SFC contributions to OA ranged from 45 to 54 % in predominantly residential areas outside the city center and amounted to 35 % in the center. In contrast, COA was highest in the center (14%), spatially aligned with restaurant locations.
These findings show that pollution sources contribute non-uniformly in different parts of Sarajevo especially during evening hours. By combining spatially resolved measurements with source apportionment, this study provides valuable insights into pollution sources and their chemical composition in Sarajevo, a highly polluted but still largely understudied area in Europe
Study of doping effects on the thermal properties of ▫▫ based photocatalysts by combined PDS and PPE technique
No full textPhotocatalysis is a environmental purification process in which pollutants are degraded into
harmless mineral substances through chemical reactions driven by light energy. This work focuses
on the study of the thermal properties of BiFeO3 (BFO) photocatalyst and its Pr- and Co-doped
derivatives (Bi(1-x)PrxFe(1-x)CoxO3 (x = 0.0, 0.02, 0.04, 0.06, 0.08, 0.1)), synthesized by sol-gel
process and co-precipitation method [1]. The impact of doping on the thermal behaviour of these
materials was evaluated using the combined Photopyroelectric calorimetry and Beam Deflection
Spectrometry [2,3]. The thermal conductivity and thermal diffusivity for undoped BFO were found
to be 1.56 ± 0.06 W/mK and 2.19 ± 0.08 mm2/s, respectively. The results indicate that the increase
in doping concentration from 2% to 10% leads to a decrease in thermal conductivity from the value
of 1.73 ± 0.07 W/mK to. 1.29 ± 0.04 W/mK, as well as a decrease in thermal diffusivity from 2.42
± 0.10 mm2/s to 1.84 ± 0.06 mm2/s (Fig.1). Such a behaviour of thermal properties is related to a
reduction in both the crystallite size and state of agglomeration with the dopant concentration what
is determined using SEM and XRD analysis. Furthermore, at the doping level of 2%, the thermal
properties are enhanced as a result of improved crystallinity and reduced number of phonon
scattering centers. These results indicatee that Pr-Co doping significantly modifies the thermal and
structural properties of the whole material, that further determine its photocatalytic activity
Podatkovna zbirka rezultatov naloge presoje sprejemljivosti stavkov, ki so permutacijske različice osnovnega besednega reda v slovenščini
No full textTabeli predstavljata številčne ocene sprejemljivosti stavkov, ki so permutacijske različice osnovnega stavka »Andrej je ujel lepega lososa« v tabeli "baza podatkov1" in osnovnega stavka »Učenka je prebrala zanimivo knjigo« v tabeli "baza podatkov2". Ocene sprejemljivosti so bile podane na Likertovi lestvici od 1 (popolnoma nesprejemljivo) do 5 (popolnoma sprejemljivo)
