Rapid growth of new atmospheric particles by nitric acid and ammonia condensation

Nature, Journal Year: 2020, Volume and Issue: 581(7807), P. 184 - 189

Published: May 13, 2020

A list of authors and their affiliations appears at the end paper New-particle formation is a major contributor to urban smog1,2, but how it occurs in cities often puzzling3. If growth rates particles are similar those found cleaner environments (1-10 nanometres per hour), then existing understanding suggests that new should be rapidly scavenged by high concentration pre-existing particles. Here we show, through experiments performed under atmospheric conditions CLOUD chamber CERN, below about +5 degrees Celsius, nitric acid ammonia vapours can condense onto freshly nucleated as small few diameter. Moreover, when cold enough (below -15 Celsius), nucleate directly an acid-base stabilization mechanism form ammonium nitrate Given these one thousand times more abundant than sulfuric acid, resulting particle extremely high, reaching well above 100 hour. However, require gas-particle system out equilibrium order sustain gas-phase supersaturations. In view strong temperature dependence measure for supersaturations, expect such transient occur inhomogeneous settings, especially wintertime, driven vertical mixing local sources traffic. Even though rapid from condensation may last only minutes, nonetheless fast shepherd smallest size range where they most vulnerable scavenging loss, thus greatly increasing survival probability. We also nucleation important relatively clean upper free troposphere, convected continental boundary layer electrical storms4,5.

Language: Английский

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Control of particulate nitrate air pollution in China

Nature Geoscience, Journal Year: 2021, Volume and Issue: 14(6), P. 389 - 395

Published: April 26, 2021

Language: Английский

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Aqueous production of secondary organic aerosol from fossil-fuel emissions in winter Beijing haze

Proceedings of the National Academy of Sciences, Journal Year: 2021, Volume and Issue: 118(8)

Published: Feb. 15, 2021

Secondary organic aerosol (SOA) produced by atmospheric oxidation of primary emitted precursors is a major contributor to fine particulate matter (PM

Language: Английский

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Rapid transition in winter aerosol composition in Beijing from 2014 to 2017: response to clean air actions

Atmospheric chemistry and physics, Journal Year: 2019, Volume and Issue: 19(17), P. 11485 - 11499

Published: Sept. 12, 2019

Abstract. The clean air actions implemented by the Chinese government in 2013 have led to significantly improved quality Beijing. In this work, we combined situ measurements of chemical components submicron particles (PM1) Beijing during winters 2014 and 2017 a regional transport model investigate impact on aerosol chemistry quantify relative contributions anthropogenic emissions, meteorological conditions, changes composition from 2017. We found that average PM1 concentration winter decreased 49.5 % (from 66.2 33.4 µg m−3). Sulfate exhibited much larger decline than nitrate ammonium, which rapid transition sulfate-driven nitrate-driven pollution wintertime. Organic (OA), especially coal combustion OA, black carbon also showed large decreasing rates, indicating effective emission control biomass burning. sulfate contribution increased fraction were highly consistent with faster reductions sulfur dioxide (SO2) due phasing out compared reduction nitrogen oxides emissions estimated bottom-up inventory. simulations these estimates reproduced suggested reduced its surrounding regions played dominant role. variations conditions contributed less 2014–2017 emissions. Finally, speculated precursor possibly altered formation mechanisms based ambient observations. observed explosive growth at humidity (RH) greater 50 was delayed higher RH 70 2017, likely caused suppressed through heterogeneous reactions decrease SO2 Thermodynamic concentrations lowered water content, particle acidity, ammonium fraction. results study demonstrate response stringent identify are major driver, could help further guide strategies China.

Language: Английский

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Fast Photochemistry in Wintertime Haze: Consequences for Pollution Mitigation Strategies

Environmental Science & Technology, Journal Year: 2019, Volume and Issue: 53(18), P. 10676 - 10684

Published: Aug. 16, 2019

In contrast to summer smog, the contribution of photochemistry formation winter haze in northern mid-to-high latitude is generally assumed be minor due reduced solar UV and water vapor concentrations. Our comprehensive observations atmospheric radicals relevant parameters during several events 2016 Beijing, however, reveal surprisingly high hydroxyl radical oxidation rates up 15 ppbv/h, which comparable values reported photochemical smog two three times larger than those determined previous Birmingham (Heard et al. Geophys. Res. Lett. 2004, 31, (18)), Tokyo (Kanaya J. Res.: Atmos. 2007, 112, (D21)), New York (Ren Environ. 2006, 40, 252-263). The active facilitates production secondary pollutants. It mainly initiated by photolysis nitrous acid ozonolysis olefins maintained an extremely efficiently cycling process driven nitric oxide. This boosted recycling generates fast ozone that are again smog. ozone, currently masked its efficient chemical removal nitrogen oxides contributing level wintertime particles. future emission regulations, such as reduction oxide emissions, therefore facing challenge reducing avoiding increase pollution at same time. Efficient control strategies mitigate Beijing may require measures similar implemented avoid summer.

Language: Английский

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A chemical cocktail during the COVID-19 outbreak in Beijing, China: Insights from six-year aerosol particle composition measurements during the Chinese New Year holiday

The Science of The Total Environment, Journal Year: 2020, Volume and Issue: 742, P. 140739 - 140739

Published: July 4, 2020

Language: Английский

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Field Determination of Nitrate Formation Pathway in Winter Beijing

Environmental Science & Technology, Journal Year: 2020, Volume and Issue: 54(15), P. 9243 - 9253

Published: June 26, 2020

Particulate nitrate (pNO3–) has often been found to be the major component of fine particles in urban air-sheds China, United States, and Europe during winter haze episodes recent years. However, there is a lack knowledge regarding experimentally determined contribution different chemical pathways formation pNO3–. Here, for first time, we combine ground tall-tower observations quantify pNO3– using observationally constrained model approach based on direct OH N2O5 air-shed. We find that gas-phase oxidation pathway (OH+NO2) daytime dominant channel over nocturnal uptake pollution episodes, with percentages 74% areas 76% suburban areas. This quite from previous studies some regions US, which was concluded account larger winter. These results indicate driving factor Beijing US different, as are mitigation strategies particulate nitrate.

Language: Английский

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Photochemical Aqueous-Phase Reactions Induce Rapid Daytime Formation of Oxygenated Organic Aerosol on the North China Plain

Environmental Science & Technology, Journal Year: 2020, Volume and Issue: 54(7), P. 3849 - 3860

Published: March 4, 2020

Secondary organic aerosol (SOA) constitutes a large fraction of worldwide, however, the formation mechanisms in polluted environments remain poorly understood. Here we observed fast daytime growth oxygenated (OOA) (with rates up to 10 μg m–3 h–1) during low relative humidity (RH, average 38 ± 19%), high RH (53 and fog periods (77 13%, occurring nighttime with reaching 100%). Evidence showed that photochemical aqueous-phase SOA (aqSOA) dominantly contributed OOA fog, while both aqSOA gas-phase (gasSOA) were important other former contributing more under latter conditions, respectively. Compared production, dark was only period negligibly increase concentrations due scavenging processes. The rapid aging, as indicated by decrease m,p-xylene/ethylbenzene ratios, promoted precursors for formation, e.g., carbonyls such methylglyoxal. Photooxidants related OH radical H2O2 also bear features even solar radiative conditions. simultaneous increases ultraviolet radiation, photooxidant, precursor levels worked together promote formation. We found biomass burning emissions can adding photooxidants precursors. Therefore, future mitigation air pollution environment would benefit from stricter control on especially

Language: Английский

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Significant Changes in Chemistry of Fine Particles in Wintertime Beijing from 2007 to 2017: Impact of Clean Air Actions

Environmental Science & Technology, Journal Year: 2019, Volume and Issue: 54(3), P. 1344 - 1352

Published: Nov. 26, 2019

The Beijing government implemented a number of clean air action plans to improve quality in the last 10 years, which contributed changes concentration fine particles and their compositions. However, quantifying impacts these interventions is challenging as meteorology masks real observed concentrations. Here, we applied machine learning technique decouple effect evaluate chemistry nonrefractory PM1 (particulate matter less than 1 μm) winter 2007, 2016, 2017 result actions. mass concentrations were 74.6, 90.2, 36.1 μg m–3 three winters, while deweathered 74.2, 78.7, 46.3 m–3, respectively. PM1, organics, sulfate, ammonium, chloride, SO2, NO2, CO decreased by −38, −46, −59, −24, −51, −89, −16, −52% comparison 2007. On contrary, nitrates increased 4%. Our results indicate that actions highly effective reducing ambient CO, but control nitrate organics remains major challenge.

Language: Английский

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Mutual promotion between aerosol particle liquid water and particulate nitrate enhancement leads to severe nitrate-dominated particulate matter pollution and low visibility

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(4), P. 2161 - 2175

Published: Feb. 26, 2020

Abstract. As has been the case in North America and western Europe, SO2 emissions have substantially reduced China Plain (NCP) recent years. Differential rates of reduction NOx concentrations result frequent occurrence particulate matter pollution dominated by nitrate (pNO3-) over NCP. In this study, we observed a polluted episode with mass fraction nonrefractory PM1 (NR-PM1) being up to 44 % during wintertime Beijing. Based on typical pNO3--dominated haze event, linkage between aerosol water uptake pNO3- enhancement, further impacting visibility degradation, investigated based field observations theoretical calculations. During development, as ambient relative humidity (RH) increased from ∼10 70 %, particle liquid ∼1 µg m−3 at beginning ∼75 fully developed period. The surface area volume, enhancing condensational loss N2O5 particles. From haze, factor 20 when only considering volume dry particles, while increasing 25 extra due uptake. Furthermore, favored thermodynamic equilibrium HNO3 phase under supersaturated NH3 atmosphere. All above results demonstrated that is enhanced elevated RH turn facilitating take-up hygroscopicity salt. Such mutual promotion enhancement can rapidly degrade air quality halve within 1 d. Reduction nitrogen-containing gaseous precursors, e.g., control traffic emissions, essential mitigating severe events

Language: Английский

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