Environmental Science Atmospheres, Год журнала: 2022, Номер 2(4), С. 687 - 701
Опубликована: Янв. 1, 2022
We characterized the chemical composition and yield of laboratory SOA generated in an oxidation flow reactor from OH Cl n -dodecane toluene, OH, Cl, Br isoprene α-pinene.
Язык: Английский
The Science of The Total Environment, Год журнала: 2023, Номер 887, С. 164117 - 164117
Опубликована: Май 11, 2023
Язык: Английский
Процитировано
27
Nature Communications, Год журнала: 2024, Номер 15(1)
Опубликована: Май 25, 2024
Abstract High concentrations of organic aerosol (OA) occur in Asian countries, leading to great health burdens. Clean air actions have resulted significant emission reductions pollutants China. However, long-term nation-wide trends OA and their causes remain unknown. Here, we present both observational model evidence demonstrating widespread decreases with a greater reduction primary than secondary (SOA) China during the period 2013 2020. Most decline is attributed reduced residential fuel burning while interannual variability SOA may been driven by meteorological variations. We find contrasting effects reducing NO x SO 2 on production which led slight overall increases SOA. Our findings highlight importance clean energy replacements multiple sectors achieving air-quality targets because high precursor emissions fluctuating chemical conditions.
Язык: Английский
Процитировано
16
The Science of The Total Environment, Год журнала: 2024, Номер 919, С. 170836 - 170836
Опубликована: Фев. 10, 2024
Язык: Английский
Процитировано
11
Environmental Science & Technology, Год журнала: 2024, Номер 58(24), С. 10652 - 10663
Опубликована: Июнь 3, 2024
Secondary organic aerosol (SOA) formation from gasoline vehicles spanning a wide range of emission types was investigated using an oxidation flow reactor (OFR) by conducting chassis dynamometer tests. Aided advanced mass spectrometric techniques, SOA precursors, including volatile compounds (VOCs) and intermediate/semivolatile (I/SVOCs), were comprehensively characterized. The reconstructed produced the speciated VOCs I/SVOCs can explain 69% measured downstream OFR upon 0.5–3 days' OH exposure. While only 10% total production, contribution is 59%, with oxygenated (O–I/SVOCs) taking up 20% that contribution. O–I/SVOCs (e.g., benzylic or aliphatic aldehydes ketones), as obscured source, account for 16% nonmethane gas (NMOG) emission. More importantly, improvement in standards, NMOG effectively mitigated 35% China 4 to 6, which predominantly attributed decrease VOCs. Real-time measurements different components well production further reveal current control measures, such advances engine three-way catalytic converter (TWC) are effective reducing "light" precursors (i.e., single-ring aromatics) but not I/SVOC emissions. Our results also highlight greater effects than previously observed urgent need investigation into their origins, i.e., incomplete combustion, lubricating oil, etc., requires improvements real-time molecular-level characterization molecules turn will benefit future design measures.
Язык: Английский
Процитировано
8
ACS Earth and Space Chemistry, Год журнала: 2025, Номер unknown
Опубликована: Фев. 10, 2025
The phase state of secondary organic aerosols (SOA) can range from liquid through amorphous semisolid to glassy solid, which is important consider as it influences various multiphase processes including SOA formation and partitioning, chemistry, cloud activation. In this study, we simulate the glass transition temperature viscosity over globe using global chemical transport model, GEOS-Chem. simulated spatial distributions show that at surface exist equatorial regions oceans, in midlatitude continental regions, solid lands with low relative humidity. predicted viscosities are mostly consistent available measurements. free troposphere, particles be 850 hPa 500 hPa, except tropical Amazonia, where viscous. Phase also exhibits seasonal variation a higher frequency winter compared warmer seasons. We calculate equilibration time scales partitioning (τeq) effective mass accommodation coefficient (αeff), indicating τeq shorter than step GEOS-Chem 20 min αeff close unity for most locations level, supporting application equilibrium partitioning. However, prolonged lowered drylands upper suggesting kinetically limited growth would need considered these future large-scale model studies.
Язык: Английский
Процитировано
1
Environmental Pollution, Год журнала: 2023, Номер 327, С. 121464 - 121464
Опубликована: Март 22, 2023
Язык: Английский
Процитировано
16
The Science of The Total Environment, Год журнала: 2024, Номер 919, С. 170633 - 170633
Опубликована: Фев. 9, 2024
Язык: Английский
Процитировано
6
Environmental Science & Technology, Год журнала: 2024, Номер 58(12), С. 5419 - 5429
Опубликована: Фев. 23, 2024
Traffic emissions are a dominant source of secondary organic aerosol (SOA) in urban environments. Though tailpipe exhaust has drawn extensive attention, the impact non-tailpipe on atmospheric SOA not been well studied. Here, closure study was performed combining tunnel experiments and dynamometer tests using an oxidation flow reactor situ photo-oxidation. Results show significant gap between field laboratory research; average formation potential from real-world fleet is 639 ± 156 mg kg fuel–1, higher than reconstructed result (188 fuel–1) based coupled with composition inside tunnel. Considering minimal variation SOA/CO emission standards, we also reconstruct CO find critical role high-emitting events burden. Different profiles gases detected exhaust, such as more abundant C6–C9 aromatics, C11–C16 species, benzothiazoles, denoting contributions to formation. Using these surrogate chemical compounds, roughly estimate that high-emitting, evaporative emission, asphalt-related tire sublimation share 14, 20, 10% budget, respectively, partially explaining research. These experimental results highlight importance SOA.
Язык: Английский
Процитировано
6
Proceedings of the National Academy of Sciences, Год журнала: 2024, Номер 121(16)
Опубликована: Апрель 11, 2024
The oxidation of cycloalkanes is important in the combustion transportation fuels and atmospheric secondary organic aerosol formation. A transient carbon-centered radical intermediate (•QOOH) cyclohexane identified through its infrared fingerprint time- energy-resolved unimolecular dissociation dynamics to hydroxyl (OH) bicyclic ether products. Although cyclohexyl ring structure leads three nearly degenerate •QOOH isomers (β-, γ-, δ-QOOH), their transition state (TS) barriers OH products are predicted differ considerably. Selective characterization β-QOOH isomer achieved at excitation energies associated with lowest TS barrier, resulting rapid decay that detected. benchmarking approach employed for calculation high-accuracy stationary point energies, particular barriers, (C 6 H 11 O 2 ), building on higher-level reference calculations smaller ethane 5 ) system. isomer-specific validated by comparison experimental product appearance rates computed statistical microcanonical rates, including significant heavy-atom tunneling, vicinity barrier. Master-equation modeling utilized extend results thermal rate constants temperatures pressures relevant combustion.
Язык: Английский
Процитировано
6
Environmental Science & Technology Letters, Год журнала: 2024, Номер 11(7), С. 738 - 745
Опубликована: Июнь 21, 2024
Semivolatile and intermediate volatility organic compounds (S/IVOCs) are known as crucial precursors of secondary aerosols (SOA), yet their specific contributions to SOA in urban areas remain unclear. Here, we investigate the real-time formation from ambient air summer Beijing utilizing an oxidation flow reactor (OFR), coupled with aerosol proton-transfer-reaction mass spectrometers. Our results show that maximum photochemical OFR reached 2.9 μg m–3 at ∼1.5 days age. Primary OA less oxidized oxygenated experience loss high ages (>3 days) OFR, whereas more continues enhancement, indicating role heterogeneous processes highly aged SOA. Closure studies demonstrate estimated contribute 50.0 ± 17.3% measured The relatively low contribution (10.3 5.2%) IVOCs emphasizes importance unmeasured S/IVOCs formation. Furthermore, illustrate impact heat waves on by enhancing biogenic emissions summer.
Язык: Английский
Процитировано
6