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A METHOD FOR QUANTIFICATION OF MINERAL DUST IN AIR BASED ON OPTICAL ABSORPTION OF PARTICLES CONCENTRATED BY A VIRTUAL IMPACTOR AND A DEVICE PERFORMING THE SAID METHOD
Luka Drinovec, Griša Močnik, IASONAS STAVROULAS, SPIROS BEZANTAKOS, Michael Pikridas, FLORIN UNGA, JEAN SCIARE, patent

Abstract: The present invention belongs to the field of devices and methods for measurement of particle concentration, more precisely to the field of devices and methods for quantification of particles based ontheir physical characteristics, especially with the use of optical means. The invention relates to a method for determination of ambient mineral dust concentration based on optical absorption of particles concentrated by a virtual impactor as well as a device performing the said method. The method comprises the following steps: sampling air samples with particle size smaller than 1 mum (PM1) andsampling air samples with particle size up to 10 mum; concentrating the samples with particle sizes up to 10 mum with a virtual impactor; measuring optical absorption of collected samples at least onewavelength from UV to IR spectre, preferably from 370 to 950 nm, most preferably at 370 nm; subtracting the absorption of the samples with particle size smaller than 1 mum from the absorption of thesample concentrated by the virtual impactor.
Keywords: dust, black carbon, aerosol
Published in RUNG: 07.03.2023; Views: 1192; Downloads: 0
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Measuring the Aerosol Light Absorption Coefficient - a Not-So-Easy Task With Relevance for the Global and Regional Climate
Griša Močnik, 2022, unpublished invited conference lecture

Abstract: The photothermal interferometer measurement of aerosol absorption, using pump lasers (532, 1064 nm) and phase sensitive detection results in 4 and 6% measurement uncertainty. It is calibrated traceably to primary standards and thereby a potential reference.
Keywords: aerosol absorption, black carbon, climate change
Published in RUNG: 20.07.2022; Views: 1294; Downloads: 0
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Measuring aerosol absorption directly - PTI methods to the rescue
Griša Močnik, unpublished invited conference lecture

Keywords: aerosol absorption, black carbon, climate change
Published in RUNG: 19.07.2022; Views: 1228; Downloads: 0
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A dual-wavelength photothermal aerosol absorption monitor : design, calibration and performance
Luka Drinovec, Uroš Jagodič, Luka Pirker, Miha Škarabot, Mario Kurtjak, Kristijan Vidović, Luca Ferrero, Bradley Visser, Jannis Röhrbein, Ernest Weingartner, Daniel M. Kalbermatter, Konstantina Vasilatou, Griša Močnik, 2022, original scientific article

Abstract: There exists a lack of aerosol absorption measurement techniques with low uncertainties and without artefacts. We have developed the two-wavelength Photothermal Aerosol Absorption Monitor (PTAAM-2λ), which measures the aerosol absorption coefficient at 532 and 1064 nm. Here we describe its design, calibration and mode of operation and evaluate its applicability, limits and uncertainties. The 532 nm channel was calibrated with ∼ 1 µmol mol−1 NO2, whereas the 1064 nm channel was calibrated using measured size distribution spectra of nigrosin particles and a Mie calculation. Since the aerosolized nigrosin used for calibration was dry, we determined the imaginary part of the refractive index of nigrosin from the absorbance measurements on solid thin film samples. The obtained refractive index differed considerably from the one determined using aqueous nigrosin solution. PTAAM-2λ has no scattering artefact and features very low uncertainties: 4 % and 6 % for the absorption coefficient at 532 and 1064 nm, respectively, and 9 % for the absorption Ångström exponent. The artefact-free nature of the measurement method allowed us to investigate the artefacts of filter photometers. Both the Aethalometer AE33 and CLAP suffer from cross-sensitivity to scattering – this scattering artefact is most pronounced for particles smaller than 70 nm. We observed a strong dependence of the filter multiple scattering parameter on the particle size in the 100–500 nm range. The results from the winter ambient campaign in Ljubljana showed similar multiple scattering parameter values for ambient aerosols and laboratory experiments. The spectral dependence of this parameter resulted in AE33 reporting the absorption Ångström exponent for different soot samples with values biased 0.23–0.35 higher than the PTAAM-2λ measurement. Photothermal interferometry is a promising method for reference aerosol absorption measurements.
Keywords: aerosol absorption, calibration, black carbon
Published in RUNG: 28.06.2022; Views: 1133; Downloads: 25
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European Aerosol Phenomenology - 8: Harmonised Source Apportionment of Organic Aerosol using 22 Year-long ACSM/AMS Datasets
Gang Chen, Francesco Canonaco, Anna Tobler, Griša Močnik, MaríaCruz Minguillón, André Prévôt, 2022, original scientific article

Abstract: Organic aerosol (OA) is a key component to total submicron particulate matter (PM1), and comprehensive knowledge of OA sources across Europe is crucial to mitigate PM1 levels. Europe has a well-established air quality research infrastructure from which yearlong datasets using 21 aerosol chemical speciation monitors (ACSMs) and 1 aerosol mass spectrometer (AMS) were gathered during 2013-2019. It includes 9 non-urban and 13 urban sites. This study developed a state-of-the-art source apportionment protocol to analyse long-term OA mass spectrum data by applying the most advanced source apportionment strategies (i.e., rolling PMF, ME-2, and bootstrap). This harmonised protocol was followed strictly for all 22 datasets, making the source apportionment results more comparable. In addition, it enables the quantifications of the most common OA components such as hydrocarbon-like OA (HOA), biomass burning OA (BBOA), cooking-like OA (COA), more oxidised-oxygenated OA (MO-OOA), and less oxidised-oxygenated OA (LO-OOA). Other components such as coal combustion OA (CCOA), solid fuel OA (SFOA: mainly mixture of coal and peat combustion), cigarette smoke OA (CSOA), sea salt (mostly inorganic but part of the OA mass spectrum), coffee OA, and ship industry OA could also be separated at a few specific sites. Oxygenated OA (OOA) components make up most of the submicron OA mass (average = 71.1%, range from 43.7 to 100%). Solid fuel combustion-related OA components (i.e., BBOA, CCOA, and SFOA) are still considerable with in total 16.0% yearly contribution to the OA, yet mainly during winter months (21.4%). Overall, this comprehensive protocol works effectively across all sites governed by different sources and generates robust and consistent source apportionment results. Our work presents a comprehensive overview of OA sources in Europe with a unique combination of high time resolution (30-240 minutes) and long-term data coverage (9-36 months), providing essential information to improve/validate air quality, health impact, and climate models.
Keywords: air pollution, source apportionment, organic aeroosl, black carbon
Published in RUNG: 03.06.2022; Views: 1788; Downloads: 12
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