Regional Transport Increases Ammonia Concentration in Beijing, China

To elucidate the critical factors influencing the ammonia (NH<sub>3</sub>) concentration in Beijing, this study combined observational analyses, backward trajectory calculations, and meteorology–chemistry coupled simulations to investigate the variations in the NH<sub>3</sub>...

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Bibliographic Details
Main Authors: Qingmei Wang, Yucong Miao, Ligang Wang
Format: Article
Language:English
Published: MDPI AG 2020-05-01
Series:Atmosphere
Subjects:
Online Access:https://www.mdpi.com/2073-4433/11/6/563
Description
Summary:To elucidate the critical factors influencing the ammonia (NH<sub>3</sub>) concentration in Beijing, this study combined observational analyses, backward trajectory calculations, and meteorology–chemistry coupled simulations to investigate the variations in the NH<sub>3</sub> concentration from 11 May to 24 June, 2015. A significant positive correlation was found between the NH<sub>3</sub> and PM<sub>2.5</sub> concentrations in Beijing. By examining the relationships between meteorological parameters and the NH<sub>3</sub> concentration, both near-surface temperature and relative humidity showed positive correlations with the NH<sub>3</sub> concentration. The higher NH<sub>3</sub> concentrations were usually associated with the warming of the upper atmosphere. Distinct wind directions were noted during the days of the top and bottom 33.3% NH<sub>3</sub> concentrations. The top 33.3% concentrations were primarily related to southwesterly winds, while the bottom ones were associated with westerly and northerly winds. Since there are strong NH<sub>3</sub> emissions in the southern plains adjacent to Beijing, the regional transport induced by the southerly prevailing winds would increase the NH<sub>3</sub> concentration in Beijing significantly. From 23 to 25 May, more than one third of NH<sub>3</sub> in Beijing was contributed by the southerly transport processes. Thus, joint efforts to reduce NH<sub>3</sub> emissions in the whole Beijing–Tianjin–Hebei region are necessary to regulate the NH<sub>3</sub> concentration in Beijing.
ISSN:2073-4433