Nitrate radicals and biogenic volatile organic compounds: oxidation, mechanisms, and organic aerosol

Atmospheric chemistry and physics, Journal Year: 2017, Volume and Issue: 17(3), P. 2103 - 2162

Published: Feb. 13, 2017

Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO3) represents one important interactions between anthropogenic emissions related to combustion and natural from biosphere. This interaction has been recognized for more than 3 decades, during which time a large body research emerged laboratory, field, modeling studies. NO3-BVOC reactions influence air quality, climate visibility through regional global budgets reactive nitrogen (particularly nitrates), ozone, aerosol. Despite its long history significance this topic in atmospheric chemistry, number uncertainties remain. These include an incomplete understanding rates, mechanisms, aerosol yields reactions, lack constraints on role heterogeneous oxidative processes associated with NO3 radical, difficulty characterizing spatial distributions BVOC within poorly mixed nocturnal atmosphere, challenge constructing appropriate boundary layer schemes non-photochemical mechanisms use state-of-the-art chemical transport chemistry-climate models. review is result workshop same title held at Georgia Institute Technology June 2015. The first half summarizes current literature particular focus recent advances instrumentation models, secondary (SOA) formation chemistry. Building understanding, second outlines impacts chemistry quality climate, suggests critical needs better constrain improve predictive capabilities

Language: Английский

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The global impacts of COVID-19 lockdowns on urban air pollution

Elementa Science of the Anthropocene, Journal Year: 2021, Volume and Issue: 9(1)

Published: Jan. 1, 2021

The coronavirus-19 (COVID-19) pandemic led to government interventions limit the spread of disease which are unprecedented in recent history; for example, stay at home orders sudden decreases atmospheric emissions from transportation sector. In this review article, current understanding influence emission reductions on pollutant concentrations and air quality is summarized nitrogen dioxide (NO2), particulate matter (PM2.5), ozone (O3), ammonia, sulfur dioxide, black carbon, volatile organic compounds, carbon monoxide (CO). first 7 months following onset pandemic, more than 200 papers were accepted by peer-reviewed journals utilizing observations ground-based satellite instruments. Only about one-third literature incorporates a specific method meteorological correction or normalization comparing data lockdown period with prior reference despite importance doing so interpretation results. We use stringency index (SI) as an indicator severity measures show how key pollutants change SI increases. observed decrease NO2 increasing general agreement inventories that account lockdown. Other compounds such O3, PM2.5, CO also broadly covered. Due chemistry O3 PM2.5 concentrations, their responses may not be linear respect primary pollutants. At most sites, we found increased, whereas decreased slightly, SI. Changes other understudied. highlight future research needs emerging sets preview state atmosphere world targeted permanent emissions. Finally, emphasize need effects meteorology, trends, when determining concentrations.

Language: Английский

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Effectiveness of ammonia reduction on control of fine particle nitrate

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(16), P. 12241 - 12256

Published: Aug. 24, 2018

Abstract. In some regions, reducing aerosol ammonium nitrate (NH4NO3) concentrations may substantially improve air quality. This can be accomplished by reductions in precursor emissions, such as nitrogen oxides (NOx) to lower nitric acid (HNO3) that partitions the aerosol, or ammonia (NH3) particle pH and keep HNO3 gas phase. Using ISORROPIA-II thermodynamic model detailed observational data sets, we explore sensitivity of NH4NO3 gas-phase NH3 NOx controls for a number contrasting locations, including Europe, United States, China. control is always effective, whereas response highly nonlinear only becomes effective at sweet spot. The analysis provides conceptual framework fundamental evaluation on relative value versus demonstrates relevance an quality parameter. We find that, regardless locations examined, it when ambient drops below approximate critical 3 (slightly higher warm slightly cold seasons) reduction leads PM2.5 mass. required amount reach efficiently decrease different sites assessed. Owing linkage between emissions agricultural productivity, substantial not feasible. Finally, controlling increase acidity evaporate will have other effects, beyond NH4NO3, increasing toxicity potentially altering deposition patterns trace nutrients.

Language: Английский

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Effects of NO<sub><i>x</i></sub> and SO<sub>2</sub> on the secondary organic aerosol formation from photooxidation of <i>α</i>-pinene and limonene

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(3), P. 1611 - 1628

Published: Feb. 5, 2018

Abstract. Anthropogenic emissions such as NOx and SO2 influence the biogenic secondary organic aerosol (SOA) formation, but detailed mechanisms effects are still elusive. We studied of on SOA formation from photooxidation α-pinene limonene at ambient relevant concentrations (NOx: < 1to 20 ppb, SO2: 0.05 to 15 ppb). In these experiments, monoterpene oxidation was dominated by OH oxidation. found that induced nucleation enhanced mass formation. strongly suppressed not only new particle also yield. However, in presence which a high number concentration particles after H2SO4, suppression yield completely or partly compensated for. This indicates largely due leading lack surface for organics condense thus significant vapor wall loss By compensating suppressing effect NOx, Aerosol spectrometer data show increasing nitrate The majority (57–77 %), even low-NOx conditions (< ∼ 1 Organic contributed 7–26 % total assuming molecular weight 200 g mol−1. had generally lower hydrogen carbon ratio (H ∕ C), compared low NOx. dependence chemical composition can be attributed branching RO2 reactions, fraction hydroperoxides higher fractions nitrates While compensate effects, combining may have an important affected interactions volatile compounds (VOCs) with anthropogenic emissions.

Language: Английский

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An evaluation of global organic aerosol schemes using airborne observations

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(5), P. 2637 - 2665

Published: March 4, 2020

Abstract. Chemical transport models have historically struggled to accurately simulate the magnitude and variability of observed organic aerosol (OA), with previous studies demonstrating that significantly underestimate concentrations in troposphere. In this study, we explore two different model OA schemes within standard GEOS-Chem chemical evaluate simulations against a suite 15 globally distributed airborne campaigns from 2008 2017, primarily spring summer seasons. These include ATom, KORUS-AQ, GoAmazon, FRAPPE, SEAC4RS, SENEX, DC3, CalNex, OP3, EUCAARI, ARCTAS ARCPAC provide broad coverage over diverse set atmospheric composition regimes – anthropogenic, biogenic, pyrogenic remote. The significant differences their treatment primary secondary components “simple scheme” (POA) as non-volatile takes fixed-yield approach (SOA) formation “complex simulates POA semi-volatile uses more sophisticated volatility basis for non-isoprene SOA, an explicit aqueous uptake mechanism isoprene SOA. Despite these substantial differences, both simple complex perform comparably across aggregate dataset ability capture (with R2 0.41 0.44, respectively). scheme displays greater skill minimizing overall bias normalized mean 0.04 compared 0.30 scheme). Across schemes, reproducing is superior evaluations approaches fidelity sulfate simulation model. However, there are performance source regimes, classified here into seven categories. Higher-resolution nested regional indicate resolution important factor capturing highly localized campaigns, while also importance well-constrained emissions inventories local meteorology, particularly Asia. Our analysis suggests treatment. It likely parameterization overestimates biogenic SOA at global scale. While study identifies factors contribute (such strong dependency on relative humidity concentrations), comparisons other drivers bias, such emissions, deposition, exogenous scheme.

Language: Английский

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Rapid dark aging of biomass burning as an overlooked source of oxidized organic aerosol

Proceedings of the National Academy of Sciences, Journal Year: 2020, Volume and Issue: 117(52), P. 33028 - 33033

Published: Dec. 14, 2020

Significance To quantify the full implications of biomass burning emissions on atmosphere, it is essential to accurately represent emission plume after has undergone chemical aging in atmosphere. Atmospheric models typically consider predominant pathway take place presence sunlight (via OH radical); however, this mechanism leads consistent underpredictions oxidized organic aerosol wintertime urban areas. Here, we show, through a combination laboratory experiments, ambient field measurements, and transport modeling, that plumes exposed NO 2 O 3 age rapidly without requiring any sunlight, thus providing an overlooked source previously not accounted for models.

Language: Английский

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Increased night-time oxidation over China despite widespread decrease across the globe

Nature Geoscience, Journal Year: 2023, Volume and Issue: 16(3), P. 217 - 223

Published: Jan. 26, 2023

Nitrogen oxides (NOx = NO + NO2) emitted from combustion and natural sources are reactive gases that regulate the composition of Earth's atmosphere. Nocturnal oxidation driven by nitrate radicals is an important but poorly understood process in atmospheric chemistry, affecting lifetimes NOx ozone particulate pollution levels. Understanding trends to formulating effective mitigation strategies understanding influence on climate. Here we analyse publicly available monitoring data assess production rates surface 2014 2021 across globe. We show have undergone strong increases China during 2014–2019 exhibited modest decreases United States European Union. Accelerated night-time has shortened lifetime summer 30% 2014–2019. This change will strongly affect formation policy implications for joint control fine pollution. Measurements increased decreased Union 2019. suggests increasing contribution air

Language: Английский

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Tropospheric ozone and NOx: A review of worldwide variation and meteorological influences

Environmental Technology & Innovation, Journal Year: 2022, Volume and Issue: 28, P. 102809 - 102809

Published: July 9, 2022

Tropospheric ozone (O3) has increased globally since the end of 20th century. Its formation undergoes complicated photochemical reactions and processes in lower boundary layer. As a result, changes O3 levels are not about one specific factor but combined process other effects such as anthropogenic emissions, topographic characteristics, meteorological influences. Consequently, published studies often show conflicting findings on levels. NOx is significant precursors generated during combustion processes. Therefore, despite efforts emission controls, reducing will guarantee downward trend. Furthermore, weather phenomena (e.g., anticyclones sea–land breezes) can enhance parameters that govern transport diffusion precursors. The review summarizes current knowledge emissions recent years. It helps to understand how regional features influence its precursors, which beneficial for efficient surface evaluation control.

Language: Английский

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Experimental and model estimates of the contributions from biogenic monoterpenes and sesquiterpenes to secondary organic aerosol in the southeastern United States

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(17), P. 12613 - 12637

Published: Aug. 31, 2018

Atmospheric organic aerosol (OA) has important impacts on climate and human health but its sources remain poorly understood. Biogenic monoterpenes sesquiterpenes are precursors of secondary (SOA), the amounts pathways SOA generation from these not well constrained by observations. We propose that less-oxidized oxygenated (LO-OOA) factor resolved positive matrix factorization (PMF) analysis mass spectrometry (AMS) data can be used as a surrogate for fresh in southeastern US. This hypothesis is supported multiple lines evidence, including lab-in-the-field perturbation experiments, extensive ambient ground-level measurements, state-of-the-art modeling. performed experiments which air perturbed injection selected sesquiterpenes, subsequent formation investigated. PMF provides an objective link between LO-OOA insights into other OA factors. Further, we use upgraded atmospheric model show modeled concentrations could reproduce both magnitude diurnal variation at sites US, building confidence our hypothesis. estimate annual average concentration US to roughly 2 μg m-3.

Language: Английский

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Long-term cloud condensation nuclei number concentration, particle number size distribution and chemical composition measurements at regionally representative observatories

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(4), P. 2853 - 2881

Published: Feb. 28, 2018

Abstract. Aerosol–cloud interactions (ACI) constitute the single largest uncertainty in anthropogenic radiative forcing. To reduce uncertainties and gain more confidence simulation of ACI, models need to be evaluated against observations, particular measurements cloud condensation nuclei (CCN). Here we present a data set – ready used for model validation long-term observations CCN number concentrations, particle size distributions chemical composition from 12 sites on 3 continents. Studied environments include coastal background, rural alpine sites, remote forests an urban surrounding. Expectedly, characteristics are highly variable across site categories. However, they also vary within them, most strongly background group, where concentrations can by up factor 30 one season. In terms activation behaviour, continental stations exhibit very similar ratios (relative particles > 20 nm) range 0.1 1.0 % supersaturation. At transition being inactive becoming active occurs over wider supersaturation spectrum. Several show strong seasonal cycles distributions, e.g. at Barrow (Arctic haze spring), (stronger influence polluted boundary layer air masses summer), rain forest (wet dry season) or Finokalia (wildfire autumn). The relatively little variability throughout year, while short-term high especially site. average hygroscopicity parameter, κ, calculated submicron was highest Mace Head (0.6) lowest station ATTO (0.2–0.3). We performed closure studies based κ–Köhler theory predict concentrations. ratio predicted measured is between 0.87 1.4 five different types κ. temporal well captured, with Pearson correlation coefficients exceeding 0.87. Information many locations important better characterise ACI their But comprehensive aerosol characterisations labour intensive costly. Hence, recommend operating “migrating-CCNCs” conduct collocated concentration distribution individual year least derive seasonally resolved parameter. This way, only continued information greater spatial coverage achieved.

Language: Английский

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