日本地球惑星科学連合2019年大会

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セッション記号 A (大気水圏科学) » A-CG 大気海洋・環境科学複合領域・一般

[A-CG42] 海洋表層-大気間の生物地球化学

2019年5月29日(水) 10:45 〜 12:15 102 (1F)

コンビーナ:宮崎 雄三(北海道大学低温科学研究所)、西岡 純(北海道大学低温科学研究所)、鈴木 光次(北海道大学)、岩本 洋子(広島大学 生物圏科学研究科)、座長:宮崎 雄三(北海道大学 低温科学研究所)、西岡 純(北海道大学 低温科学研究所)

12:00 〜 12:15

[ACG42-06] Impacts of ammonia on gas-particle partition and AWC during the 2016 APHH-Beijing campaign: inducing effects of nitrate ammonium

*baozhu Ge1Xiaobin Xu2Zhiqiang Ma3Xiaole PAN1Zhe WANG1,4Weili Lin5Bin Ouyang6Danhui Xu1James Lee7Mei Zheng8Dongsheng Ji1Yele Sun1Huabin Dong8Freya Anne Squires7Pingqing Fu1Zifa Wang1 (1.State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China、2.State Key Laboratory of Severe Weather & Key Laboratory for Atmospheric Chemistry of China Meteorological Administration, Chinese Academy of Meteorological Sciences, Beijing 100081, China、3.Institute of Urban Meteorology, China Meteorological Administration, Beijing, China、4.Research Institute for Applied Mechanics (RIAM), Kyushu University, Fukuoka, Japan、5.College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China、6.Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK、7.National Centre for Atmospheric Science Department of Chemistry, University of York, York, YO10 5DD, UK、8.State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China)

キーワード:Ammonia, partition, aerosol acidity, APHH-Beijing, PM2.5, NCP

Atmospheric NH3 plays a vital role not only in the environmental ecosystem but also in atmosphere chemistry. To fully understand the effects of NH3 on the formation of haze pollution in Beijing, ambient NH3 and related species were measured at high resolutions during the wintertime Air Pollution and Human Health-Beijing (APHH-Beijing) campaign in 2016. Simulations were made to gain insights into impacts of NH3 on the formation of secondary inorganic aerosols (SIAs) and regional fine particle pollution. We found that the total NHx (gaseous NH3+particle NH4+) was mostly in excess of the SO42--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 non-polluted conditions, respectively, and enhanced the formation of particle phase nitrate. During polluted periods, SIAs contributed most to PM2.5 and were highly correlated with aerosol water content (AWC), indicating the importance of heterogeneous reactions in haze formation. Our analysis suggests that NH4NO3 is the most important factor driving the formation of AWC, 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 DRH and hence lead to hygroscopic growth even under lower RH conditions and the wet aerosol particles become better medium for rapid heterogeneous reactions. A further increase of RH promotes the positive feedback "AWC-heterogeneous reactions" and ultimately leads to the formation of severe haze. Both our observational and modelling results suggest that the control of NH3 may be more effective in reducing PM2.5 under current emissions conditions in the North China Plain (NCP).