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. Ammonia (NH3) plays an important role in particulate matter formation;hence, its atmospheric level is relevant to human health and climatechange. Due to different relative distributions of NH3 sources,concentrations of atmospheric NH3 may behave differently in urban andrural areas. However, few parallel long-term observations of NH3 exist toreveal the different behaviors of NH3 concentrations at urbanand rural sites in a same region. In this study, online ammonia analyzerswere used to continuously observe atmospheric NH3 concentrations at anurban site and a suburban site in Beijing from 13 January 2018 to 13 January 2019. The observed mixing ratio of NH3 averaged 21±14 ppb(range of 1.6–133 ppb) at the urban site and 22±15 ppb (range of0.8–199 ppb) at the suburban site. The NH3 mixing ratios at the urbanand suburban sites exhibited similar seasonal variations, with high valuesin summer and spring and low values in autumn and winter. The hourly meanNH3 mixing ratios at the urban site were highly correlated (R=0.849,P&lt;0.01) with those at the suburban site; however, the averagediurnal variations in the NH3 mixing ratios at the urban and suburbansites differed significantly, which implies different contributions fromNH3 sources and sinks at the urban and suburban sites. In addition tothe emission sources, meteorological factors were closely related to thechanges in the NH3 concentrations. For the same temperature (relativehumidity) at the urban and suburban sites, the NH3 mixing ratiosincreased with relative humidity (temperature). Relative humidity was thefactor with the strongest influence on the NH3 mixing ratio indifferent seasons at the two sites. The relationships between the NH3concentrations and temperature (relative humidity) varied from season toseason and showed differences between the urban and suburban sites. Thereasons for the different relationships need to be investigated in futurestudies. Higher wind speed mainly from the northwest sector lowered theNH3 mixing ratios at both sites. Similarly to other primary pollutantsin Beijing, the NH3 mixing ratios were high when impacted by air massesfrom the southern sector.

Measurement report: Exploring NH&lt;sub&gt;3&lt;/sub&gt; behavior in urban and suburban Beijing: comparison and implications

Measurement report: Exploring NH<sub>3</sub> behavior in urban and suburban Beijing: comparison and implications