By the same authors

Role of Ammonia on the Feedback Between AWC and Inorganic Aerosol Formation During Heavy Pollution in the North China Plain

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  • Baozhu Ge
  • Xiaobin Xu
  • Zhiqiang Ma
  • Xiaole Pan
  • Zhe Wang
  • Weili Lin
  • Bin Ouyang
  • Danhui Xu
  • James Lee
  • Mei Zheng
  • Dongsheng Ji
  • Yele Sun
  • Huabin Dong
  • Freya Anne Squires
  • Pingqing Fu
  • Zifa Wang


Publication details

JournalEarth and Space Science
DateAccepted/In press - 24 Aug 2019
DateE-pub ahead of print - 29 Aug 2019
DatePublished (current) - Sep 2019
Issue number9
Number of pages19
Pages (from-to)1675-1693
Early online date29/08/19
Original languageEnglish


Atmospheric NH3 plays a vital role not only in the environmental ecosystem but also in atmosphere chemistry. To further understand the effects of NH3 on the formation of haze pollution in Beijing, ambient NH3 and related species were measured and simulated at high resolutions during the wintertime Air Pollution and Human Health-Beijing (APHH-Beijing) campaign in 2016. We found that the total NHx (gaseous NH3+particle NH4 +) was mostly in excess of the SO4 2−-NO3 -NH4 +-water equilibrium system during our campaign. This NHx excess made medium aerosol acidity, with the median pH value being 3.6 and 4.5 for polluted and nonpolluted conditions, respectively, and enhanced the formation of particle phase nitrate. Our analysis suggests that NH4NO3 is the most important factor driving the increasing of aerosol water content with NO3 controlling the prior pollution stage and NH4 + the most polluted stage. Increased formation of NH4NO3 under excess NHx, especially during the nighttime, may trigger the decreasing of aerosol deliquescence relative humidity even down to less than 50% and hence lead to hygroscopic growth even under RH conditions lower than 50% and the wet aerosol particles become better medium for rapid heterogeneous reactions. A further increase of RH promotes the positive feedback “aerosol water content-heterogeneous reactions” and ultimately leads to the formation of severe haze. Modeling results by Nested Air Quality Prediction Monitor System (NAQPMS) show the control of 20% NH3 emission may affect 5–11% of particulate matter PM2.5 formation under current emissions conditions in the North China Plain.

Bibliographical note

© 2019, The Author(s).

    Research areas

  • aerosol water content, ammonia, APHH-Beijing, NCP, partition, PM

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