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Chemical characterization of PM2.5 and source apportionment of organic aerosol in New Delhi, India
Urs Baltensperger, Griša Močnik, Surender Singh, Suresh Tiwari, Deewan Bisht, Atul Srivastava, Suneeti Mishra, Navaneeth Thamban, Ashutosh Shukla, Vipul Lalchandani, Francesco Canonaco, Deepika Bhattu, Anna Tobler, Sachchida Tripathi, J. G. Slowik, André S. H. Prévôt, 2020, original scientific article

Abstract: Delhi is one of the most polluted cities worldwide and a comprehensive understanding and deeper insight into the air pollution and its sources is of high importance. We report 5 months of highly time-resolved measurements of non-refractory PM2.5 and black carbon (BC). Additionally, source apportionment based on positive matrix factorization (PMF) of the organic aerosol (OA) fraction is presented. The highest pollution levels are observed during winter in December/January. During that time, also uniquely high chloride concentrations are measured, which are sometimes even the most dominant NR-species in the morning hours. With increasing temperature, the total PM2.5 concentration decreases steadily, whereas the chloride concentrations decrease sharply. The concentrations measured in May are roughly 6 times lower than in December/January. PMF analysis resolves two primary factors, namely hydrocarbon-like (traffic-related) OA (HOA) and solid fuel combustion OA (SFC-OA), and one or two secondary factors depending on the season. The uncertainties of the PMF analysis are assessed by combining the random a-value approach and the bootstrap resampling technique of the PMF input. The uncertainties for the resolved factors range from ±18% to ±19% for HOA, ±7% to ±19% for SFC-OA and ±6 % to ±11% for the OOAs. The average correlation of HOA with eBCtr is R2 = 0.40, while SFC-OA has a correlation of R2 = 0.78 with eBCsf. Anthracene (m/z 178) and pyrene (m/z 202) (PAHs) are mostly explained by SFC-OA and follow its diurnal trend (R2 = 0.98 and R2 = 0.97). The secondary oxygenated aerosols are dominant during daytime. The average contribution during the afternoon hours (1 pm–5 pm) is 59% to the total OA mass, with contributions up to 96% in May. In contrast, the primary sources are more important during nighttime: the mean nightly contribution (22 pm–3 am) to the total OA mass is 48%, with contributions up to 88% during some episodes in April.
Found in: osebi
Keywords: New Delhi, PM2.5, Source apportionment, PMF
Published: 20.07.2020; Views: 1291; Downloads: 0
.pdf Fulltext (4,71 MB)

Real-time characterization and source apportionment of fine particulate matter in the Delhi megacity area during late winter
Vipul Lalchandan, Varun Kumar, Anna Tobler, M.T. Navaneeth, Suneeti Mishra, J. G. Slowik, Deepika Bhattu, Pragati Rai, Rangu Satish, Dilip Ganguly, Tiwari Tiwari, Neeraj Rastogi, Tiwari Sashi, Griša Močnik, André S. H. Prévôt, Sachchida Tripathi, 2021, original scientific article

Abstract: National Capital Region (NCR) encompassing New Delhi is one of the most polluted urban metropolitan areas in the world. Real-time chemical characterization of fine particulate matter (PM1 and PM2.5) was carried out using three aerosol mass spectrometers, two aethalometers, and one single particle soot photometer (SP2) at two sites in Delhi (urban) and one site located ~40 km downwind of Delhi, during January-March, 2018. The campaign mean PM2.5 (NR-PM2.5 + BC) concentrations at the two urban sites were 153.8±109.4 μg.m-3 and 127.8±83.2 μg.m-3, respectively, whereas PM1 (NR-PM1 + BC) was 72.3 ± 44.0 μg.m-3 at the downwind site. PM2.5 particles were composed mostly of organics (43-44)% followed by chloride (14-17)%, ammonium (9-11)%, nitrate (9%), sulfate (8-10)%, and black carbon (11-16)%, whereas PM1 particles were composed of 47% organics, 13% sulfate as well as ammonium, 11% nitrate as well as chloride, and 5% black carbon. Organic aerosol (OA) source apportionment was done using positive matrix factorization (PMF), solved using an advanced multi-linear engine (ME-2) model. Highly mass-resolved OA mass spectra at one urban and downwind site were factorized into three primary organic aerosol (POA) factors including one traffic-related and two solid-fuel combustion (SFC), and three oxidized OA (OOA) factors. Whereas unit mass resolution OA at the other urban site was factorized into two POA factors related to traffic and SFC, and one OOA factor. OOA constituted a majority of the total OA mass (45-55)% with maximum contribution during afternoon hours ~(70-80)%. Significant differences in the absolute OOA concentration between the two urban sites indicated the influence of local emissions on the oxidized OA formation. Similar PM chemical composition, diurnal and temporal variations at the three sites suggest similar type of sources affecting the particulate pollution in Delhi and adjoining cities, but variability in mass concentration suggest more local influence than regional.
Found in: osebi
Keywords: source apportionment, air pollution, particulate matter, Delhi
Published: 25.01.2021; Views: 2086; Downloads: 0
.pdf Fulltext (2,92 MB)

Equal abundance of summertime natural and wintertime anthropogenic Arctic organic aerosols
Olga Popovicheva, Tuuka Petäjä, Andreas Massling, Jakob K. Nøjgaard, Jean-Luc Jaffrezo, Lin Huang, Heidi Hellén, Hannele Hakola, Wendy Zhang, Mika Vestenius, Henrik Skov, Sangeeta Sharma, Mirko Severi, Jürgen Schnelle-Kreis, Claire E. Moffett, Konstantinos Eleftheriadis, Giulia Calzolai, Silvia Becagli, Wenche Aas, Pragati Rai, Francesco Canonaco, Kaspar R. Daellenbach, Houssni Lamkaddam, Roberto Casotto, Deepika Bhattu, Katja Dzepina, Vaios Moschos, Rebecca J. Sheesley, Rita Traversi, Karl Espen Yttri, Julia Schmale, André S. H. Prévôt, Urs Baltensperger, Imad El Haddad, 2022, original scientific article

Abstract: Aerosols play an important yet uncertain role in modulating the radiation balance of the sensitive Arctic atmosphere. Organic aerosol is one of the most abundant, yet least understood, fractions of the Arctic aerosol mass. Here we use data from eight observatories that represent the entire Arctic to reveal the annual cycles in anthropogenic and biogenic sources of organic aerosol. We show that during winter, the organic aerosol in the Arctic is dominated by anthropogenic emissions, mainly from Eurasia, which consist of both direct combustion emissions and long-range transported, aged pollution. In summer, the decreasing anthropogenic pollution is replaced by natural emissions. These include marine secondary, biogenic secondary and primary biological emissions, which have the potential to be important to Arctic climate by modifying the cloud condensation nuclei properties and acting as ice-nucleating particles. Their source strength or atmospheric processing is sensitive to nutrient availability, solar radiation, temperature and snow cover. Our results provide a comprehensive understanding of the current pan-Arctic organic aerosol, which can be used to support modelling efforts that aim to quantify the climate impacts of emissions in this sensitive region.
Found in: osebi
Keywords: Arctic, Organic aerosols, Emission sources, Climate change
Published: 01.03.2022; Views: 252; Downloads: 0
.pdf Fulltext (1,89 MB)

Sarajevo Canton Winter Field Campaign 2018
Griša Močnik, Jasna Huremović, Sabina Žero, Roberto Casotto, Athanasia Vlachou, Anna Tobler, Francesco Canonaco, Deepika Bhattu, Katja Džepina, Vaios Moschos, 2020, published scientific conference contribution abstract

Abstract: Nowadays, urban centres in countries of the Western Balkan region (including Bosnia and Herzegovina (B&H)) are experiencing some of the poorest European and global air quality due to the extensive use of solid fuels (e.g., wood, coal) and old vehicle fleet. Western Balkan countries lack state-of-the-art atmospheric sciences research despite high levels of ambient pollution, which makes the efforts to understand the mechanisms of their air pollution imperative. The city of Sarajevo, the capital of B&H, is situated in a basin surrounded by mountains. Particularly 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 on-line aerosol measurements and collection of daily, continuous filter PM10 samples for off-line 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 (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 different off-line 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 (OC/EC), water-soluble organic carbon, polycyclic aromatic hydrocarbons, levoglucosan, and 14C content of total carbon to evaluate OA chemical composition. 3) Major inorganic anions and cations to evaluate aerosol inorganic species. 4) Metal content in aerosol determined by two analytical techniques (AAS and ICP-MS). SAFICA on-line measurements of black carbon (Aethalometer) and the particle number concentration (Condensation Particle Counter and Optical Particle Sizer) enabled the insights into the daily evolution of primary pollutants and an assessment of aerosol size and number distribution. The combined SAFICA results for on- and off-line measurements will be presented. Our results show that the carbon-containing species make ~2/3 of PM10 mass and the majority are oxygenated, water-soluble OA species with an average OM/OC = 1.9 (Fig.1). 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, including the advantages and limitations of SAFICA data set, and give the recommendations for future studies.
Found in: osebi
Keywords: Sarajevo, urban air pollution, PM10, PM2.5
Published: 26.05.2021; Views: 886; Downloads: 2
.pdf Fulltext (2,01 MB)
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