English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. Regional transport and heterogeneous reactions have been shown to play crucial roles in haze formation over a megacity cluster centered on Beijing. In this study, theupdated Nested Air Quality Prediction Model System (NAQPMS) and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model were employed to investigate the evolution ofaerosols – in terms of the number concentration, size distribution, and degree of aging – in Beijing during six haze episodes between 15 November and15 December 2016, as part of the Air Pollution and Human Health–Beijing(APHH-Beijing) winter campaign of 2016. The model exhibited reasonableperformance not only with respect to mass concentrations of PM 2.5 and its componentsin Beijing but also regarding the number concentration, size distribution, and degree of aging. We revealed that regional transport played a non-negligible role inhaze episodes, with contributions of 14 %–31 % to the surfacePM 2.5 mass concentration. The contribution of regional transport tosecondary inorganic aerosols was larger than that to primary aerosols(30 %–63 % and 3 %–12 %, respectively). The chemical transformation of SO2 along the transport pathway from source regions to Beijing was themajor source of SO 4 2 - . We also found that sulfate formed outsideBeijing from SO2 emitted in Beijing; this sulfate was then blown backto Beijing and considerably influenced haze formation. Along the transportpathway, aerosols underwent aging, which altered the mass ratio of the coating of black carbon to black carbon ( RBC ) and the size distribution of numberconcentrations. During the episodes, the geometric mean diameter (GMD)increased from less than 100 nm at the initial site to approximately 120 nmat the final site (Beijing), and the RBC increased from 2–4 to 4–8.During haze episodes with high humidity, the average contributions of gas andaqueous chemistry, heterogeneous chemistry, and primary emission to sulfatewere comparable. However, their relative contributions varied with pollutionlevels. Primary emissions had the greatest impact under light to moderatepollution levels, whereas heterogeneous chemistry had a stronger effect underhigh pollution levels.

atmospheric chemistry and physics

Modeling of aerosol property evolution during winter haze episodes over a megacity cluster in northern China: roles of regional transport and heterogeneous reactions of SO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;