title: Atmospheric ammonia and its impacts on regional air quality over the megacity of Shanghai, China.
abstract: Atmospheric ammonia (NH3) has great environmental implications due to its important role in ecosystem and global nitrogen cycle, as well as contribution to secondary particle formation. Here, we report long-term continuous measurements of NH3 at different locations (i.e. urban, industrial and rural) in Shanghai, China, which provide an unprecedented portrait of temporal and spatial characteristics of atmospheric NH3 in and around this megacity. In addition to point emission sources, air masses originated from or that have passed over ammonia rich areas, e.g. rural and industrial sites, increase the observed NH3 concentrations inside the urban area of Shanghai. Remarkable high-frequency NH3 variations were measured at the industrial site, indicating instantaneous nearby industrial emission peaks. Additionally, we observed strong positive exponential correlations between NH4(+)/(NH4(+)+NH3) and sulfate-nitrate-ammonium (SNA) aerosols, PM2.5 mass concentrations, implying a considerable contribution of gas-to-particle conversion of ammonia to SNA aerosol formation. Lower temperature and higher humidity conditions were found to favor the conversion of gaseous ammonia to particle ammonium, particularly in autumn. Although NH3 is currently not included in China's emission control policies of air pollution precursors, our results highlight the urgency and importance of monitoring gaseous ammonia and improving its emission inventory in and around Shanghai.
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science &Engineering, Fudan University, Shanghai 200433, China.|School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, China.|Atmospheric Chemistry and Climate Group, Institute of Physical Chemistry Rocasolano, CSIC, Madrid 28006, Spain.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Wang
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science &Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Jialiang
authors.initials: J
authors.lastname: Nan
authors.affiliation: Shanghai Institute of Measurement and Testing Technology, Shanghai 201203, China.
authors.forename: Chanzhen
authors.initials: C
authors.lastname: Shi
authors.affiliation: Shanghai Environmental Monitoring Center, Shanghai 200235, China.
authors.forename: Qingyan
authors.initials: Q
authors.lastname: Fu
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science &Engineering, Fudan University, Shanghai 200433, China.|Shanghai Environmental Monitoring Center, Shanghai 200235, China.
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science &Engineering, Fudan University, Shanghai 200433, China.|Shanghai Environmental Monitoring Center, Shanghai 200235, China.
authors.forename: Dongfang
authors.initials: D
authors.lastname: Wang
authors.affiliation: Shanghai Environmental Monitoring Center, Shanghai 200235, China.
authors.forename: Huxiong
authors.initials: H
authors.lastname: Cui
authors.affiliation: Atmospheric Chemistry and Climate Group, Institute of Physical Chemistry Rocasolano, CSIC, Madrid 28006, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Saiz-Lopez
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science &Engineering, Fudan University, Shanghai 200433, China.|Fudan Tyndall Centre, Fudan University, Shanghai 200433, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhou
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000641:Ammonia / Q000032:analysis*; D002681:China; D005740:Gases / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry; D052638:Particulate Matter / Q000032:analysis; D012621:Seasons; D013431:Sulfates / Q000737:chemistry; D013696:Temperature
chemical_list: D000393:Air Pollutants; D005740:Gases; D009566:Nitrates; D052638:Particulate Matter; D013431:Sulfates; D000641:Ammonia