The Science of The Total Environment, Год журнала: 2022, Номер 839, С. 156342 - 156342
Опубликована: Май 29, 2022
Язык: Английский
Atmospheric chemistry and physics, Год журнала: 2021, Номер 21(12), С. 9859 - 9886
Опубликована: Июль 1, 2021
Abstract. In recent years, intense haze events in megacities such as Beijing have received significant attention. Although secondary organic aerosol (SOA) has been identified a major contributor to events, knowledge of its sources and formation mechanisms remains uncertain. We investigate this question through the first field deployment extractive electrospray ionisation time-of-flight mass spectrometer (EESI-TOF) Beijing, together with an Aerodyne long-time-of-flight (L-TOF AMS). Measurements were performed during autumn winter 2017, capturing transition from non-heating heating seasons. Source apportionment resolved four factors related primary aerosols (traffic, cooking, biomass burning, coal combustion), well SOA. Of SOA factors, two solid fuel combustion (SFC), one generated aqueous chemistry, mixed/indeterminate sources. The SFC spectral signatures corresponding aromatic oxidation products, while factor was characterised by small acids diacids unusually low CO+/CO2+ fragment ratios measured AMS. Solid dominant source season. However, comparably event also observed season dominated factor. During event, chemistry promoted combination high relative humidity air masses passing over high-NOx regions south east leading particulate nitrate. resulting liquid water content highly correlated concentration These results highlight strong compositional variability between different indicating need consider multiple pathways precursor describe Beijing.
Язык: Английский
Процитировано
51
Atmospheric chemistry and physics, Год журнала: 2021, Номер 21(7), С. 5463 - 5476
Опубликована: Апрель 8, 2021
Abstract. Volatility and viscosity have substantial impacts on gas–particle partitioning, formation evolution of aerosol hence the predictions aerosol-related air quality climate effects. Here volatility at a rural site (Gucheng) an urban (Beijing) in North China Plain (NCP) summer winter were investigated by using thermodenuder coupled with high-resolution mass spectrometer. The effective saturation concentration (C*) organic (OA) was smaller than that (0.55 µg m−3 vs. 0.71–0.75 m−3), indicating OA NCP is more volatile due to enhanced primary emissions from coal combustion biomass burning. distributions varied largely different among factors. In particular, we found hydrocarbon-like (HOA) contained nonvolatile compounds compared coal-combustion-related OA. oxidized oxygenated (MO-OOA) showed overall lower less OOA (LO-OOA) both winter, yet MO-OOA be relative humidity (RH) dependent showing properties higher RH. Our results demonstrated composition chemical pathways under RH levels. glass transition temperature (Tg) are estimated recently developed parameterization formula. Tg Beijing (291.5 K) (289.7–290.0 K), while it greatly suggested existed mainly as solid (RH = 29 ± 17 %), but semisolids 48 25 %) Gucheng 68 24 %). These important implication kinetically limited partitioning may need considered when simulating secondary NCP.
Язык: Английский
Процитировано
50
Environmental Science & Technology, Год журнала: 2021, Номер 55(6), С. 3568 - 3581
Опубликована: Март 3, 2021
Peroxyacetyl nitrate (PAN) is an important indicator for photochemical pollution, formed similar to ozone in the photochemistry of certain volatile organic compounds (VOCs) presence nitrogen oxides, and has displayed surprisingly high concentrations during wintertime that were better correlated particulate rather than concentrations, which reasons remained unknown. In this study, observations PAN, VOCs, PM2.5, HONO, various trace gases investigated find relationship between aerosols PAN formation. Wintertime pollution was affirmed by (average: 1.2 ± 1.1 ppb, maximum: 7.1 ppb), despite low concentrations. determined its oxygenated VOC (OVOC) precursor NO/NO2 ratios can be well parameterized based on understanding their chemical relationship. Data analysis box modeling results suggest formation mostly contributed aging processes involving OH oxidation or photolysis ozonolysis pathways. Heterogeneous reactions have supplied key oxidants such as produced radicals upon photolysis, promoting OVOC thereby enhancing production, explaining observed PM2.5-OVOC-PAN intercorrelation. turn, parts these OVOCs might participate secondary aerosol, further aggravating haze a feedback. Low temperatures enable long-range transport downwind regions, how will impact capacity requires assessment future studies.
Язык: Английский
Процитировано
50
Atmospheric Environment, Год журнала: 2022, Номер 273, С. 118978 - 118978
Опубликована: Янв. 30, 2022
Язык: Английский
Процитировано
33
Atmospheric chemistry and physics, Год журнала: 2022, Номер 22(11), С. 7713 - 7726
Опубликована: Июнь 15, 2022
Abstract. Secondary organic aerosols (SOAs) account for a large fraction of atmospheric aerosol mass and play significant roles in visibility impairment by scattering solar radiation. However, comprehensive evaluations SOA abilities under ambient relative humidity (RH) conditions on the basis field measurements are still lacking due to difficulty simultaneously direct quantifications efficiency dry state water uptake abilities. In this study, chemical physical properties were conducted winter Guangzhou (lasting about 3 months) using humidified nephelometer system speciation monitor. A modified multilinear regression model was proposed retrieve dry-state efficiencies (MSEs, defined as coefficient per unit mass) components. The more oxidized oxygenated (MOOA) with an O/C ratio 1.17 identified most efficient light component. On average, 34 % contribution MOOA total submicron contributed 51 scattering. overall hygroscopicity parameter κOA quantified directly through closure, parameters components further retrieved assuming hydrophobic primary aerosols. highest ability among factors revealed κMOOA reaching 0.23, thus enhancing fractional particular, found be even higher than those ammonium nitrate RH <70 %, which inorganic component, demonstrating that had strongest air (average 57 %) during Guangzhou. During observation period, secondary dominantly degradation (∼70 %), substantial contributions from (16 average), impacts degradation. findings study demonstrate attention needs paid property changes future improvement investigations. Also, studies formation needed better parameterize its radiative effects models implement targeted control strategies precursors improvement.
Язык: Английский
Процитировано
32
Geophysical Research Letters, Год журнала: 2024, Номер 51(4)
Опубликована: Фев. 20, 2024
Abstract Activation of biomass burning aerosols (BBA) and fossil fuel combustion (FFA) in fogs clouds significantly impact regional air quality through aqueous chemistry climate by affecting cloud microphysics. However, we lack direct observations how these behave clouds. Using a newly developed aerosol‐cloud sampling system, conducted during fog events found that BBA, despite their high organic content, effectively contributed to super‐micron interstitial droplets low supersaturation fogs. In contrast, FFA, predominantly externally mixed organic, did not grow beyond the size due near‐hydrophobic nature. Measurements under supersaturations relevant for formation revealed portions FFA could serve as condensation nuclei, but only when exceeded ∼0.14%. These findings have broad implications future investigations into influence BBA on interactions with
Язык: Английский
Процитировано
7
Faraday Discussions, Год журнала: 2020, Номер 226, С. 207 - 222
Опубликована: Окт. 5, 2020
Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in North China Plain. The Multiphase chemistry experiment Fogs and Aerosols Plain (McFAN) investigated physicochemical mechanisms leading to formation a focus on contributions multiphase processes aerosols fogs. We integrated observations multiple platforms regional box model simulations identify characterize key oxidation producing sulfate, nitrate secondary organic aerosols. An outdoor twin-chamber system was deployed conduct kinetic experiments under real atmospheric conditions comparison literature data from laboratory studies. were spanning years since 2017 an intensive field campaign performed 2018. location site minimizes fast transition between clean polluted air masses, regimes representative for observed at measurement Gucheng near Beijing. consecutive multi-year document recent trends PM2.5 corresponding changes aerosol physical chemical properties, enabling in-depth investigations established newly proposed formation. This study is mainly focusing obtained To investigate chemistry, results are presented discussed by means three characteristic cases: low humidity, high humidity fog. find strong relative dependence compositions, suggesting important role chemistry. Compared period, both PM1 show higher mass fraction inorganic (SIA, as nitrate, sulfate ammonium) (SOA) during fog episodes. composition further influence e.g., hygroscopicity parameter κ single scattering albedo SSA cases. campaign-averaged pH 5.1 ± 0.9, which variation driven water content (AWC) concentrations. Overall, McFAN provides new evidence reactions regulating properties regions.
Язык: Английский
Процитировано
46
The Science of The Total Environment, Год журнала: 2021, Номер 808, С. 152191 - 152191
Опубликована: Дек. 5, 2021
Язык: Английский
Процитировано
40
Atmospheric chemistry and physics, Год журнала: 2021, Номер 21(21), С. 16183 - 16201
Опубликована: Ноя. 4, 2021
Abstract. Organic aerosol (OA) is a major component of tropospheric submicron that contributes to air pollution and causes adverse effects on human health. Chemical transport models have difficulties in reproducing the variability OA concentrations polluted areas, hindering understanding budget sources. Herein, we apply both process-based observation-constrained schemes simulate GEOS-Chem. Comprehensive data sets surface OA, components, secondary organic (SOA) precursors, oxidants were used for model–observation comparisons. The base generally underestimate SOA China. In revised schemes, updates made emissions, volatility distributions, yields semivolatile intermediate-volatility compounds (SVOCs IVOCs) additional nitrous acid With all model improvements, can reproduce observed mass show spatial seasonal consistency with each other. Our best simulations suggest anthropogenic SVOCs IVOCs are dominant source SOA, contribution over 50 % most China, which should be considered mitigation future. residential sector may predominant winter, despite large uncertainty remaining emissions from northern industry also an important IVOCs, especially summer. More SVOC IVOC measurements needed constrain their emissions. Besides, results highlight sensitivity hydroxyl radical (OH) levels winter environments. addition sources lead 30 greater It good OH quality models.
Язык: Английский
Процитировано
37
The Science of The Total Environment, Год журнала: 2021, Номер 786, С. 147418 - 147418
Опубликована: Май 4, 2021
Язык: Английский
Процитировано
36