Variations and sources of volatile organic compounds (VOCs) in urban region: insights from measurements on a tall tower

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(16), P. 10567 - 10587

Published: Aug. 19, 2022

Abstract. Volatile organic compounds (VOCs) are key precursors of ozone and particulate matter, which the two dominant air pollutants in urban environments. However, compositions sources VOCs aloft have rarely been reported so far. To address this highly time-resolved measurements were made by a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) at 450 m platform on Canton Tower Guangzhou, China. A combination situ modeling techniques was used to characterize variations VOCs. Five identified from positive matrix factorization (PMF) analysis, namely daytime mixed (e.g., biogenic emissions secondary formation), visitor-related human breath, cooking, volatilization ethanol-containing products), vehicular–industrial, regional transport, volatile chemical product (VCP) (i.e., personal care contributing average 21 %, 30 28 10 11 % total VOC (TVOC) mixing ratios, respectively. We observe that contributions source, mainly composed ethanol, followed with variation visitor numbers tower well. The VCP-dominated source only had an contribution ∼5.7 ppb during campaign, accounting for small fraction (11 %) TVOC ratios but large (22 OH reactivity. fractions reactive species, e.g., monoterpenes (49 %), attributed indicating important VCPs ambient concentrations these species Vertical profiles (namely NOx, ozone, Ox, PM2.5), measured 5, 118, 168, 488 m, exhibited more evident gradients night than owing stronger stability nocturnal boundary layer. Mixing nighttime generally decreased time when located residual layer markedly increased impacted ground level. results study demonstrated composition characteristics aloft, could provide valuable implications making strategies control pollutants.

Language: Английский

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A synergistic ozone-climate control to address emerging ozone pollution challenges

One Earth, Journal Year: 2023, Volume and Issue: 6(8), P. 964 - 977

Published: Aug. 1, 2023

Tropospheric ozone threatens human health and crop yields, exacerbates global warming, fundamentally changes atmospheric chemistry. Evidence has pointed toward widespread increases in the troposphere, particularly surface is chemically complex difficult to abate. Despite past successes some regions, a solution new challenges of pollution warming climate remains unexplored. In this perspective, by compiling measurements at ∼4,300 sites worldwide between 2014 2019, we show emerging challenge pollution, featuring unintentional rise due uncoordinated emissions reduction increasing penalty. On basis shared emission sources, interactive chemical mechanisms, synergistic effects propose ozone-climate control strategy incorporating joint fine particulate matter. This presents an opportunity alleviate tropospheric forthcoming low-carbon transition.

Language: Английский

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Temperature-dependent emissions dominate aerosol and ozone formation in Los Angeles

Science, Journal Year: 2024, Volume and Issue: 384(6702), P. 1324 - 1329

Published: June 20, 2024

Despite declines in transportation emissions, urban North America and Europe still face unhealthy air pollution levels. This has challenged conventional understanding of the sources their volatile organic compound (VOC) precursors. Using airborne flux measurements to map emissions a wide range VOCs, we demonstrate that biogenic terpenoid contribute ~60% emitted VOC OH reactivity, ozone, secondary aerosol formation potential summertime Los Angeles this contribution strongly increases with temperature. implies control nitrogen oxides is key reducing ozone Angeles. We also show some anthropogenic increase temperature, which an effect not represented current inventories. Air mitigation efforts must consider climate warming will change emission amounts composition.

Language: Английский

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Identifying and correcting interferences to PTR-ToF-MS measurements of isoprene and other urban volatile organic compounds

Atmospheric measurement techniques, Journal Year: 2024, Volume and Issue: 17(2), P. 801 - 825

Published: Jan. 31, 2024

Abstract. Proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) is a technique commonly used to measure ambient volatile organic compounds (VOCs) in urban, rural, and remote environments. PTR-ToF-MS known produce artifacts from ion fragmentation, which complicates the interpretation quantification of key atmospheric VOCs. This study evaluates extent fragmentation other ionization processes impact urban measurements ions typically assigned isoprene (m/z 69, C5H8H+), acetaldehyde 45, CH3CHO+), benzene 79, C6H6H+). Interferences are identified using gas chromatography (GC) pre-separation, these interferences quantified ground-based airborne number US cities, including Las Vegas, Los Angeles, New York City, Detroit. In regions with low biogenic emissions (e.g., Vegas), higher-carbon aldehydes cycloalkanes emitted anthropogenic sources may contribute m/z 69 by as much 50 % during day, while majority signal at attributed night. higher fraction studies, likely results differences reactivity between interfering species along subsequent changes VOC mixture altitudes. For PTR masses, 45 observed due O2+ VOCs solvents, becoming more important source areas. We present methods correct interferences, provide better agreement GC isomer-specific molecules. These observations show utility deploying pre-separation for spectra.

Language: Английский

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Indoor Air Sources of Outdoor Air Pollution: Health Consequences, Policy, and Recommendations: An Official American Thoracic Society Workshop Report

Annals of the American Thoracic Society, Journal Year: 2024, Volume and Issue: 21(3), P. 365 - 376

Published: March 1, 2024

Section:ChooseTop of pageAbstract <

Language: Английский

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Modeling secondary organic aerosol formation from volatile chemical products

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(24), P. 18247 - 18261

Published: Dec. 16, 2021

Volatile chemical products (VCPs) are commonly-used consumer and industrial items that an important source of anthropogenic emissions. Organic compounds from VCPs evaporate on atmospherically relevant time scales include many species secondary organic aerosol (SOA) precursors. However, the chemistry leading to SOA, particularly intermediate volatility (IVOCs), has not been fully represented in regional-scale models such as Community Multiscale Air Quality (CMAQ) model, which tend underpredict SOA concentrations urban areas. Here we develop a model represent formation VCP The incorporates new emissions inventory employs three classes emissions: siloxanes, oxygenated IVOCs, nonoxygenated IVOCs. estimated produce 1.67 μg m-3 noontime doubling current predictions reducing mass concentration bias -75% -58% when compared observations Los Angeles 2010. While emitted similar quantities, is dominated by Formaldehyde show relationships temperature signatures indicating common sources and/or chemistry. This work suggests contribute up half must better precursors predict enhancement SOA.

Language: Английский

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Oxidation Flow Reactor Results in a Chinese Megacity Emphasize the Important Contribution of S/IVOCs to Ambient SOA Formation

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 56(11), P. 6880 - 6893

Published: Dec. 13, 2021

Oxygenated volatile organic compounds (OVOCs) and secondary aerosol (SOA) formation potential of ambient air in Guangzhou, China was investigated using a field-deployed oxidation flow reactor (OFR). The OFR used to mimic hours weeks atmospheric exposure hydroxyl (OH) radicals within the 2–3 min residence time. A comprehensive investigation on variation VOCs OVOCs as function OH is shown. Substantial acids nitrogen-containing OVOC species were observed. Maximum SOA observed following 1–4 equiv days' exposure. produced from known/measured VOC/IVOC precursors such single-ring aromatics long-chain alkanes can account for 52–75% measured under low NOx 26–60% high conditions based laboratory yield parametrizations. To our knowledge, this first time that contribution (8–20%) (C8–C20) alkane quantified direct measurement. By additionally estimating unmeasured semivolatile intermediate volatility (S/IVOCs) are committed with C8–C20 alkanes, 64–100% be explained, signifying important S/IVOCs large cyclic SOA.

Language: Английский

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Vehicle Emissions and Urban Air Quality: 60 Years of Progress

Atmosphere, Journal Year: 2022, Volume and Issue: 13(5), P. 650 - 650

Published: April 20, 2022

The past 60 years have seen large reductions in vehicle emissions of particulate matter (PM), nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HCs), sulfur dioxide (SO2), and lead (Pb). Advanced emission after-treatment technologies been developed for gasoline diesel vehicles to meet increasingly stringent regulations, yielding absolute from the on-road fleet despite increased miles traveled. As a result reduced other sources, air quality cities across U.S. Europe has improved greatly. Turn-over fleet, regulations (such as Tier 3 U.S., LEV III California, Euro 6 Europe, upcoming rules these same regions), large-scale introduction electric will even lower further improvements quality. We review historical trends discuss future outlook.

Language: Английский

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Investigating Changes in Ozone Formation Chemistry during Summertime Pollution Events over the Northeastern United States

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(22), P. 15312 - 15327

Published: Oct. 11, 2022

Understanding the local-scale spatial and temporal variability of ozone formation is crucial for effective mitigation. We combine tropospheric vertical column densities (VCDTrop) formaldehyde (HCHO) nitrogen dioxide (NO2), referred to as HCHO-VCDTrop NO2-VCDTrop, retrieved from airborne remote sensing TROPOspheric Monitoring Instrument (TROPOMI) with ground-based measurements investigate changes in precursors inferred chemical production regime on high-ozone days May–August 2018 over two Northeast urban domains. Over New York City (NYC) Baltimore/Washington D.C. (BAL/DC), increases across domain, but higher NO2-VCDTrop occurs mainly centers exceedance (when maximum daily 8 h average (MDA8) exceeds 70 ppb at any monitor region). The ratio proposed an indicator sensitivity local surface rates its precursors, generally days, implying a transition toward more NOx-sensitive that should lead efficacy NOx controls highest NYC BAL/DC. Warmer temperatures enhanced influence emissions boundary layer are accompanied by slower wind speeds BAL/DC stronger, southwesterly winds NYC.

Language: Английский

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Home is Where the Pipeline Ends: Characterization of Volatile Organic Compounds Present in Natural Gas at the Point of the Residential End User

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(14), P. 10258 - 10268

Published: June 28, 2022

The presence of volatile organic compounds (VOCs) in unprocessed natural gas (NG) is well documented; however, the degree to which VOCs are present NG at point end use largely uncharacterized. We collected 234 whole samples across 69 unique residential locations Greater Boston metropolitan area, Massachusetts. were measured for methane (CH4), ethane (C2H6), and nonmethane VOC (NMVOC) content (including tentatively identified compounds) using commercially available USEPA analytical methods. Results revealed 296 NMVOC constituents NG, 21 (or approximately 7%) designated as hazardous air pollutants. Benzene (bootstrapped mean = 164 ppbv; SD 16; 95% CI: 134-196) was detected along with hexane (98% detection), toluene (94%), heptane cyclohexane (89%), contributing a total concentration NMVOCs distribution-grade 6.0 ppmv (95% 5.5-6.6). While exhibited significant spatial variability, over twice much temporal variability observed, wintertime benzene nearly eight-fold greater than summertime. By previous leakage data, we estimated that 120-356 kg/yr annual emissions throughout not currently accounted inventories, an unaccounted-for indoor portion. NG-odorant (tert-butyl mercaptan isopropyl mercaptan) used estimate NG-CH4 21.3 16.7-25.9) could persist undetected ambient given known odor detection thresholds. This implies may be underappreciated source both CH4 associated VOCs.

Language: Английский

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