title: Fossil Fuel Combustion-Related Emissions Dominate Atmospheric Ammonia Sources during Severe Haze Episodes: Evidence from (15)N-Stable Isotope in Size-Resolved Aerosol Ammonium.
abstract: The reduction of ammonia (NH3) emissions is urgently needed due to its role in aerosol nucleation and growth causing haze formation during its conversion into ammonium (NH4(+)). However, the relative contributions of individual NH3 sources are unclear, and debate remains over whether agricultural emissions dominate atmospheric NH3 in urban areas. Based on the chemical and isotopic measurements of size-resolved aerosols in urban Beijing, China, we find that the natural abundance of (15)N (expressed using δ(15)N values) of NH4(+) in fine particles varies with the development of haze episodes, ranging from -37.1‰ to -21.7‰ during clean/dusty days (relative humidity: ∼ 40%), to -13.1‰ to +5.8‰ during hazy days (relative humidity: 70-90%). After accounting for the isotope exchange between NH3 gas and aerosol NH4(+), the δ(15)N value of the initial NH3 during hazy days is found to be -14.5‰ to -1.6‰, which indicates fossil fuel-based emissions. These emissions contribute 90% of the total NH3 during hazy days in urban Beijing. This work demonstrates the analysis of δ(15)N values of aerosol NH4(+) to be a promising new tool for partitioning atmospheric NH3 sources, providing policy makers with insights into NH3 emissions and secondary aerosols for regulation in urban environments.
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences , Beijing 100029, China.
authors.forename: Yuepeng
authors.initials: Y
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences , Beijing 100029, China.
authors.forename: Shili
authors.initials: S
authors.lastname: Tian
authors.affiliation: Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology , Chinese Academy of Sciences , Shenyang, Liaoning 110164, China.
authors.forename: Dongwei
authors.initials: D
authors.lastname: Liu
authors.affiliation: Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology , Chinese Academy of Sciences , Shenyang, Liaoning 110164, China.
authors.forename: Yunting
authors.initials: Y
authors.lastname: Fang
authors.affiliation: National Climate Center, China Meteorological Administration, Beijing 100081, China.
authors.forename: Xiaying
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University , Beijing 100084, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University , Beijing 100084, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zheng
authors.affiliation: Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States.
authors.forename: Greg
authors.initials: G
authors.lastname: Michalski
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences , Beijing 100029, China.
authors.forename: Yuesi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000336:Aerosols; D000393:Air Pollutants; D000641:Ammonia; D064751:Ammonium Compounds; D005579:Fossil Fuels; D007554:Isotopes
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D064751:Ammonium Compounds; D005579:Fossil Fuels; D007554:Isotopes; D000641:Ammonia