Diverse response of surface ozone to COVID-19 lockdown in China

The Science of The Total Environment, Год журнала: 2021, Номер 789, С. 147739 - 147739

Опубликована: Май 15, 2021

Язык: Английский

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Agricultural Fertilization Aggravates Air Pollution by Stimulating Soil Nitrous Acid Emissions at High Soil Moisture

Environmental Science & Technology, Год журнала: 2021, Номер 55(21), С. 14556 - 14566

Опубликована: Окт. 18, 2021

Nitrogen lost from fertilized soil is a potentially large source of atmospheric nitrous acid (HONO), major precursor the hydroxyl radical. Yet, impacts fertilizer types and other influencing factors on HONO emissions are unknown. As result, current state-of-the-art models lack an appropriate parameterization scheme to quantify impact air quality after fertilization. Here, we report laboratory measurements high soils at 75-95% water-holding capacity applying three common fertilizers, which contrasts with previous lower predictions moisture. Urea use leads largest release compared two commonly used fertilizers (ammonium bicarbonate ammonium nitrate). The significant promotion effect fertilization lasted up 1 week. Implementation lab-derived parametrization in chemistry transport model (CMAQ) significantly improved postfertilization rural site agriculture-intensive North China Plain increased regionally averaged daytime OH, O3, daily fine particulate nitrate concentrations by 41, 8, 47%, respectively. results our study underscore necessity include this modeling chemistry. Fertilizer structure adjustments may reduce improve polluted regions intense agriculture.

Язык: Английский

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Heterogeneous Nitrate Production Mechanisms in Intense Haze Events in the North China Plain

Journal of Geophysical Research Atmospheres, Год журнала: 2021, Номер 126(9)

Опубликована: Апрель 24, 2021

Abstract Studies of wintertime air quality in the North China Plain (NCP) show that particulate‐nitrate pollution persists despite rapid reduction NO x emissions. This intriguing ‐nitrate relationship may originate from non‐linear nitrate‐formation chemistry, but it is unclear which feedback mechanisms dominate NCP. In this study, we re‐interpret observations 17 O excess nitrate (∆ O(NO 3 − )) Beijing using GEOS‐Chem (GC) chemical transport model to estimate importance various nitrate‐production pathways and how their contributions change with intensity haze events. We also analyze relationships between other metrics y chemistry [PM 2.5 ] simulations. find on average has a negative bias −0.9‰ −36% for ∆ ) [O x,major (≡ + [NO 2 [p‐NO ]), respectively, while overestimating nitrogen oxidation ratio ([NO ]/([NO ])) by +0.12 intense haze. The discrepancies become larger more attribute biases an overestimate ‐uptake aerosols underestimate concentrations. Our findings highlight need address uncertainties related heterogeneous air‐quality models. combined assessment results suggest N 5 uptake clouds dominant pathway Beijing, its rate limited ozone under high‐NO ‐high‐PM conditions. Nitrate production rates continue increase as long increases ], creating reduces effectiveness mitigation.

Язык: Английский

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Photodissociation of particulate nitrate as a source of daytime tropospheric Cl2

Nature Communications, Год журнала: 2022, Номер 13(1)

Опубликована: Фев. 17, 2022

Chlorine atoms (Cl) are highly reactive and can strongly influence the abundances of climate air quality-relevant trace gases. Despite extensive research on molecular chlorine (Cl2), a Cl precursor, in polar atmosphere, its sources other regions still poorly understood. Here we report daytime Cl2 concentrations up to 1 ppbv observed coastal area Hong Kong, revealing large source (2.7 pptv s-1 at noon). Field laboratory experiments indicate that photodissociation particulate nitrate by sunlight under acidic conditions (pH < 3.0) activate chloride account for production. The high significantly increased atmospheric oxidation. Given ubiquitous existence chloride, nitrate, aerosols, propose photolysis is significant globally. This so far unaccounted have substantial impacts chemistry.

Язык: Английский

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Non-linear response of PM&lt;sub&gt;2.5&lt;/sub&gt; to changes in NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; and NH&lt;sub&gt;3&lt;/sub&gt; emissions in the Po basin (Italy): consequences for air quality plans

Atmospheric chemistry and physics, Год журнала: 2021, Номер 21(12), С. 9309 - 9327

Опубликована: Июнь 17, 2021

Abstract. Air pollution is one of the main causes damages to human health in Europe, with an estimate about 380 000 premature deaths per year EU28, as result exposure fine particulate matter (PM2.5) only. In this work, we focus on specific region Po basin, a where chemical regimes are most complex, showing important non-linear processes, especially those related interactions between NOx and NH3. We analyse sensitivity PM2.5 concentration NH3 emissions by means set EMEP model simulations performed different levels emission reductions, from 25 % up total switch-off emissions. Both single combined precursor reduction scenarios applied determine efficient strategies quantify reductions. The results confirmed peculiarity secondary formation characterised contrasting within distances few (hundred) kilometres, well responses reductions during wintertime. One striking slight increase when NOx-rich areas, such surroundings Bergamo. increased oxidative capacity atmosphere cause induced emission. This process could have contributed absence significant decrease COVID-19 lockdowns many European cities. It account for designing air quality plans, since it lead transitionary increases at some locations winter measures gradually implemented. While regimes, determined relative importance vs. show large variations seasonally spatially, they not very sensitive moderate (up 50 %–60 %) Beyond strength, concentrations become certain areas basin mainly

Язык: Английский

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