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https://doi.org/10.5194/egusphere-2024-375
https://doi.org/10.5194/egusphere-2024-375
11 Apr 2024
 | 11 Apr 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Atmospheric NH3 in urban Beijing: long-term variations and implications for secondary inorganic aerosol control

Ziru Lan, Xiaoyi Zhang, Weili Lin, Xiaobin Xu, Zhiqiang Ma, Jun Jin, Lingyan Wu, and Yangmei Zhang

Abstract. Ammonia (NH3) has major effects on the environment and climate. In-situ measurements of NH3 concentrations taken between June 2009 and July 2020 at an urban site in Beijing were analyzed to study their long-term behaviors, responses to meteorological conditions and influences on the formation of secondary inorganic aerosols (SIAs). The total average NH3 mixing ratio was 26.9 ± 19.3 ppb (median, 23.5 ppb). NH3 mixing ratios initially increased and peaked in 2017 but subsequently decreased, resulting in an overall decrease of 24 % from 2009 to 2020. Notably, the long-term trend for NH3 at the ground level did not align with the trends derived from satellite observations and emission estimates. It exhibited distinct seasonal variation but also complex diurnal patterns across multiple seasons and years. The NH3 concentration exhibited a stronger correlation with the water vapor (H2O) concentration than with air temperature. Thermodynamic modeling revealed the nonlinear response of SIAs to NH3. Although reducing NH3 concentrations can improve air quality during winter, controlling acid gas concentrations has a greater effect than controlling NH3 concentrations on reducing SIA concentrations. The increase in the proportion (mass concentration) of ammonium salts in SIAs during the observation period indicates that measures to control NH3 concentrations should be prioritized.

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Ziru Lan, Xiaoyi Zhang, Weili Lin, Xiaobin Xu, Zhiqiang Ma, Jun Jin, Lingyan Wu, and Yangmei Zhang

Status: open (until 23 May 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-375', Anonymous Referee #1, 06 May 2024 reply
  • RC2: 'Comment on egusphere-2024-375', Anonymous Referee #2, 08 May 2024 reply
Ziru Lan, Xiaoyi Zhang, Weili Lin, Xiaobin Xu, Zhiqiang Ma, Jun Jin, Lingyan Wu, and Yangmei Zhang
Ziru Lan, Xiaoyi Zhang, Weili Lin, Xiaobin Xu, Zhiqiang Ma, Jun Jin, Lingyan Wu, and Yangmei Zhang

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Short summary
Our study examined the long-term trends of atmospheric ammonia in urban Beijing from 2009 to 2020. We found that the trends didn't match satellite data or emissions estimates, revealing complexities in ammonia sources. While seasonal variations in ammonia were temperature-dependent, daily variations were correlated with water vapor. We also found an increasing contribution of ammonia reduction, emphasizing its importance in mitigating fine particulate matter in Beijing.