Diurnal emission variation of ozone precursors: Impacts on ozone formation during Sep. 2019

The Science of The Total Environment, Journal Year: 2024, Volume and Issue: 929, P. 172591 - 172591

Published: April 23, 2024

Language: Английский

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Comprehensive multiphase chlorine chemistry in the box model CAABA/MECCA: implications for atmospheric oxidative capacity

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(23), P. 15165 - 15180

Published: Dec. 13, 2023

Abstract. Tropospheric chlorine chemistry can strongly impact the atmospheric oxidation capacity and composition, especially in urban environments. To account for these reactions, gas- aqueous-phase Cl of community box model Chemistry As A Boxmodel Application/Module Efficiently Calculating Atmosphere (CAABA/MECCA) has been extended. In particular, an explicit mechanism ClNO2 formation following N2O5 uptake to aerosols developed. The updated applied two environments with different concentrations NOx (NO + NO2): New Delhi (India) Leicester (United Kingdom). shows a sharp build-up at sunrise through Cl2 photolysis both Besides photolysis, ClO+NO reaction ClONO are also prominent sources Leicester. High-NOx conditions tend suppress nighttime due titration O3 thus lead lower ClNO2, contrast Major loss is its on chloride, producing Cl2, which consequently leads photolysis. reactivities OH much higher Delhi; however, Cl/OH reactivity ratio up ≈ 9 times greater contribution significant even exceeds (by 2.9 times) that during morning hours Sensitivity simulations suggest additional consumption volatile organic compounds (VOCs) active enhances OH, HO2, RO2 near sunrise. simulation results have important implications future studies air quality.

Language: Английский

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Variation in chemical composition and volatility of oxygenated organic aerosol in different rural, urban, and mountain environments

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(4), P. 2607 - 2624

Published: Feb. 28, 2024

Abstract. The apparent volatility of atmospheric organic aerosol (OA) particles is determined by their chemical composition and environmental conditions (e.g., ambient temperature). A quantitative, experimental assessment the respective importance these two factors remains challenging, especially in measurements. We present molecular oxygenated OA (OOA) different rural, urban, mountain environments (including Chacaltaya, Bolivia; Alabama, US; Hyytiälä, Finland; Stuttgart Karlsruhe, Germany; Delhi, India) based on deployments a filter inlet for gases aerosols coupled to high-resolution time-of-flight ionization mass spectrometer (FIGAERO-CIMS). find average larger carbon numbers (nC​​​​​​​) lower oxygen-to-carbon (O : C) ratios at urban sites (nC: 9.8 ± 0.7; O C: 0.76 0.03; ±1 standard deviation) compared rural 8.8 0.6; 0.80 0.05) stations 8.1 0.8; 0.91 0.07), indicative emission sources chemistry. Compounds containing only carbon, hydrogen, oxygen atoms (CHO) contribute most total OOA (79.9 5.2 %), accordance with proximity forested areas (66.2 5.5 % 72.6 4.3 sites). largest contribution nitrogen-containing compounds (CHON) found (27.1 consistent higher NOx levels. Moreover, we parametrize (saturation concentrations, Csat) using information compare it bulk derived from thermal desorption within FIGAERO. differences Csat values up ∼ 3 orders magnitude variation profiles (thermograms) across locations systems. From our study, draw general conclusion that temperature) do not directly affect but rather indirectly influencing chemistry environment thus composition. comprehensive dataset provides results show complex thermodynamics changes during its lifetime atmosphere. conclude generally description suffices predict volatility, least qualitatively. Our study new insights will help guide choices of, e.g., descriptions model frameworks such as air quality models cloud parcel models.

Language: Английский

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Significant chlorine emissions from biomass burning affect the long-term atmospheric chemistry in Asia

National Science Review, Journal Year: 2024, Volume and Issue: 11(9)

Published: Aug. 13, 2024

Biomass burning (BB) is a major source of trace gases and particles in the atmosphere, influencing air quality, radiative balance, climate. Previous studies have mainly focused on BB emissions carbon nitrogen species with less attention chlorine. Reactive chlorine chemistry has significant effects atmospheric quality. However, quantitative information from BB, particularly long-term trend associated impacts, limited both regional global scales. Here, we report (2001-2018) high-resolution emission inventory for chlorine-containing compounds (HCl, chloride, CH

Language: Английский

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Changing optical properties of black carbon and brown carbon aerosols during long-range transport from the Indo-Gangetic Plain to the equatorial Indian Ocean

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(20), P. 11911 - 11925

Published: Oct. 24, 2024

Abstract. Atmospheric aerosols strongly influence the global climate through their light absorption properties (e.g., black carbon (BC) and brown (BrC)) scattering sulfate). This study presents simultaneous measurements of ambient-aerosol chemical composition obtained at three large-footprint southern Asian receptor sites during South Pollution Experiment (SAPOEX) from December 2017 to March 2018. The BC mass cross section (BC-MAC678) values increased 3.5 ± 1.3 Bangladesh Climate Observatory Bhola (BCOB), located exit outflow Indo-Gangetic Plain, 6.4 two regional observatories, Maldives Hanimaadhoo (MCOH) Gan (MCOG), representing an increase 80 %. likely reflects a scavenging fractionation, resulting in population finer with higher MAC678 that has greater longevity. At same time, BrC-MAC365 decreased by factor 3 Plain (IGP) equatorial Indian Ocean, due photochemical bleaching organic chromophores. high chlorine-to-sodium ratio BCOB, near source region, suggests significant contribution chorine anthropogenic activities. Particulate Cl− potential be converted into Cl radicals, which can affect oxidation capacity polluted air. Moreover, is shown nearly fully consumed long-range transport. results this synoptic study, conducted on large scale, provide rare observational constraints optical ambient (and BrC) over scales, away emission sources. They also contribute significantly understanding aging effect as pollution disperses tropical ocean.

Language: Английский

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Impact of Heatwaves and Declining NO_x on Nocturnal Monoterpene Oxidation in the Urban Southeastern United States

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(17)

Published: Aug. 28, 2024

Abstract Nighttime oxidation of monoterpenes (MT) via the nitrate radical (NO 3 ) and ozone (O contributes to formation secondary organic aerosol (SOA). This study uses observations in Atlanta, Georgia from 2011 2022 quantify trends nighttime production NO (PNO O concentrations compare model outputs EPA's Air QUAlity TimE Series Project (EQUATES). We present urban‐suburban gradients their fractional importance (F) for MT oxidation. Both EQUATES show a decline PNO , with modeled declining faster than observations. Despite decreasing we find that continues dominate nocturnal boundary layer (NBL) (F NO3 = 60%) 2017, 2021, 2022, which is consistent 80%) 2013 2019. contrasts an anticipated F based on prior residual layer, where dominant oxidant. Using two case studies heatwaves summer extreme heat events can increase leading short lifetimes (<1 hr) high gas‐phase production. Regardless presence heatwaves, our findings suggest sustained urban SE US under x emissions, highlight need improved representation chemistry‐transport models additional along rural gradients.

Language: Английский

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