Changes in tropospheric air quality related to the protection of stratospheric ozone in a changing climate

Photochemical & Photobiological Sciences, Journal Year: 2023, Volume and Issue: 22(5), P. 1129 - 1176

Published: June 13, 2023

Ultraviolet (UV) radiation drives the net production of tropospheric ozone (O

Language: Английский

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Significant Impact of a Daytime Halogen Oxidant on Coastal Air Quality

Environmental Science & Technology, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 24, 2025

Chlorine radicals (Cl·) are highly reactive and affect the fate of air pollutants. Several field studies in China have revealed elevated levels daytime molecular chlorine (Cl2), which, upon photolysis, release substantial amounts Cl· but poorly represented current chemical transport models. Here, we implemented a parametrization for formation Cl2 through photodissociation particulate nitrate acidic environments into regional model assessed its impact on coastal quality during autumn South China. The could reproduce over 70% high level measured at site, revealing discernible presence released adjacent areas. Abundant alters oxidative capacity atmosphere, consequently increasing O3 (6–12%) PM2.5 (10–16%) concentrations high-NOx areas reducing (3%) concentration low-NOx Accounting chemistry shifts – precursor relationships from VOC limited to mixed or NOx -limited regimes, enhancing benefits emission reduction mitigating pollution. Our findings suggest that tightening control two pollutants, SO2, would alleviate production adverse quality.

Language: Английский

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Impact of Molecular Chlorine Production from Aerosol Iron Photochemistry on Atmospheric Oxidative Capacity in North China

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: 58(28), P. 12585 - 12597

Published: July 3, 2024

Elevated levels of atmospheric molecular chlorine (Cl

Language: Английский

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Effects of Relative Humidity and Photoaging on the Formation, Composition, and Aging of Ethylbenzene SOA: Insights from Chamber Experiments on Chlorine Radical-Initiated Oxidation of Ethylbenzene

ACS Earth and Space Chemistry, Journal Year: 2024, Volume and Issue: 8(4), P. 675 - 688

Published: April 1, 2024

The oxidation of alkyl-substituted aromatic molecules produces oxygenated volatile organic compounds (OVOCs) and secondary aerosols (SOA) that are major components ambient urban air. Despite their ubiquity, the impacts variable conditions, such as relative humidity (RH) actinic exposure, on physicochemical processes contribute to SOA formation still subject ongoing research refinement. In this work, we perform laboratory environmental chamber experiments use an I– FIGAERO–CIMS examine molecular composition high-NOx ethylbenzene products in response varied (dry 40% RH, 60% RH) during either dark aging or photoaging (with ∼354 nm UV-A lights). Experiments performed a mixed Cl OH radical environment. Compared chemistry, chemistry forms greater amount nitroaromatic by enhancing benzaldehyde phenolic H abstraction while also forming several organochlorine may serve tracers for which C2H3ClO2 (presumably chloroacetic acid) appears be most consistent stable. Organonitrate (ON) undergo hydrolytic photolytic losses. Nitroaromatic condense more efficiently under humid presumably due relatively high solubility hydroxy dihydroxy molecules, but do not appear stable condensed phase photoaging. Small oxygenates make up substantial portion increases at RH (due increased uptake) photolysis fragmentation). Photoaging initially leads degree oligomerization before continued eventual loss these other compounds. Our results show substantially impact evolution many gas- particle-phase species produced suggest factors can exert strong control over evolution, particularly regions.

Language: Английский

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Daytime Atmospheric Halogen Cycling through Aqueous-Phase Oxygen Atom Chemistry

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(29), P. 15652 - 15657

Published: July 18, 2023

Halogen atoms are important atmospheric oxidants that have unidentified daytime sources from photochemical halide oxidation in sea salt aerosols. Here, we show the photolysis of nitrate aqueous chloride solutions generates nitryl (ClNO2) addition to Cl2 and HOCl. Experimental modeling evidence suggests O(3P) formed minor channel oxidizes HOCl, which reacts with nitrite form ClNO2. This chemistry is different than currently accepted mechanisms involving by OH could shift our understanding halogen cycling lower atmosphere.

Language: Английский

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Significant Impact of Reactive Chlorine on Complex Air Pollution Over the Yangtze River Delta Region, China

Journal of Geophysical Research Atmospheres, Journal Year: 2023, Volume and Issue: 128(22)

Published: Nov. 14, 2023

The chlorine radical (Cl) plays a crucial role in the formation of secondary air pollutants by determining total atmospheric oxidative capacity (AOC). However, there are still large discrepancies among studies on chemistry, mainly due to uncertainties from three aspects: (a) Anthropogenic emissions reactive species disinfectant usage typically overlooked. (b) heterogeneous reaction uptake coefficients used quality models resulted certain differences. (c) co-effect anthropogenic and natural is rarely investigated. In this study, Weather Research Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) modeling system (updated with 21 new reactions comprehensive inventory) was simulate combined impact coastal city cluster Yangtze River Delta (YRD) region. results indicate that updated gas-phase chemistry can significantly enhance AOC 21.3%, 8.7%, 43.3%, 58.7% spring, summer, autumn, winter, respectively. This more evident inland areas high Cl concentrations. Our updates also increases monthly mean maximum daily 8-hr average (MDA 8) O3 mixing ratio 4.1-7.0 ppbv different seasons. Additionally, promotes fine particulate matter (PM2.5), enhancements 4.7-13.3 μg/m3 study underlines significance adding full updating models, demonstrates may over regions.

Language: Английский

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Reply on RC1

Published: Jan. 20, 2025

Abstract. HO_X radicals (OH and HO₂) are crucial oxidants that determine atmospheric oxidation capacity the production of secondary pollutants; however, their sources sinks remain incompletely understood in certain forest maritime environments. This study measured HO₂ OH concentrations using a chemical ionisation mass spectrometer at subtropical rural site southern China from 12 November to 19 December 2022. The average peak were 3.50 ± 2.47 × 10⁶ cm⁻³ for 1.34 0.93 10⁸ HO₂. Calculations based on an observation-constrained model revealed overestimation during warm periods field study. These inaccuracies resulted overestimations rates simulation by up 98 % ozone 341 nitric acid. Our highlights need further improving understanding sources/sinks

Language: Английский

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HOCl Formation Driven by Photochemical Processes Enhanced Atmospheric Oxidation Capacity in a Coastal Atmosphere

Environmental Science & Technology, Journal Year: 2025, Volume and Issue: unknown

Published: March 6, 2025

Chlorine (Cl) radicals can profoundly affect the atmospheric oxidation capacity and fates of pollutants. Hypochlorous acid (HOCl) is a potentially crucial Cl precursor, yet understanding its formation mechanisms impacts still limited. Here, we observed high concentrations HOCl in coastal city Southeast China during autumn 2022, with an average daytime peak 181 ppt. Machine learning analysis identified Cl2, O3, nitrate, temperature, iron as primary factors affecting distribution. Beyond Cl2 photolysis, both nitrate photolysis aerosol photochemistry also contributed to radical production, which drove production through reactions involving ClO HO2 presence O3. Both OH released via increased levels ROx by ∼10%, thereby enhancing O3 generation capacity. Our findings emphasize significant role chemistry suggest that controlling could alleviate adverse on air quality.

Language: Английский

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Dimethyl sulfide chemistry over the industrial era: comparison of key oxidation mechanisms and long-term observations

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(7), P. 4083 - 4106

Published: April 10, 2025

Abstract. Dimethyl sulfide (DMS) is primarily emitted by marine phytoplankton and oxidized in the atmosphere to form methanesulfonic acid (MSA) sulfate aerosols. Ice cores regions affected anthropogenic pollution show an industrial-era decline MSA, which has previously been interpreted as indicating a abundance. However, simultaneous increase DMS-derived (bioSO4) Greenland ice core suggests that pollution-driven oxidant changes caused MSA influencing relative production of versus bioSO4. Here we use GEOS-Chem, global chemical transport model, zero-dimensional box model over three time periods (preindustrial era, peak North Atlantic NOx pollution, 21st century) investigate drivers bioSO4, examine whether four DMS oxidation mechanisms reproduce trends seasonality observations. We find GEOS-Chem simulations can only partially bioSO4 wide variation results reflects sensitivity mechanism concentrations. Our support hypothesized nitrate radical industrial increases production, but competing factors such BrO result increased some simulations, inconsistent with To improve understanding oxidation, future work should aqueous-phase chemistry, produces 82 %–99 % our constrain atmospheric concentrations, including radical, hydroxyl reactive halogens.

Language: Английский

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Modeling Tropospheric Aqueous Interfacial Chemistry and Bulk Interaction with CAPRAM-HET2.0

ACS Earth and Space Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: May 5, 2025

Language: Английский

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