Ambient concentration and dry deposition of major inorganic nitrogen species at two urban sites in Sichuan Basin, China.
To assess pollution levels of major inorganic nitrogen species and their atmospheric deposition input to sensitive ecosystems in Sichuan Basin, southwest China, ambient concentrations of oxidized (NOy∼ NO2, HNO3, NO3-) and reduced (NHx= NH3, NH4+) nitrogen species were collected at two urban sites during four one-month periods, each in a different season from July 2014 to April 2015. Estimated annual mean concentration of NOywas 20.3 and 13.5 μg N m-3in Chengdu and Wanzhou, respectively, and NHxwas 16.9 and 13.6 μg N m-3, respectively. Back trajectory cluster analysis indicated that high levels of NOyand NHxin Chengdu were mainly caused by local emissions while those in Wanzhou were caused by both the local emissions and long-range transport of pollutants. On annual basis, NO2contributed the most to NOy, followed by NO3-and HNO3, accounting for 87.5%, 10.5% and 2.0%, respectively, of NOyin Chengdu, and 91.4%, 6.9% and 1.7%, respectively, in Wanzhou. NH3was the predominant contributor to NHx, contributing 65.6% and 72.2% in Chengdu and Wanzhou, respectively. Dry deposition fluxes were estimated using the inferential method with measured ambient concentrations and modelled dry deposition velocities. The total inorganic nitrogen dry deposition flux was estimated to be 21.4 and 8.5 kg N ha-1yr-1, with 44.3% and 41.4% from NOyin Chengdu and Wanzhou, respectively. NO2and NH3each contributed about 80% of NOyand NHxdry deposition, respectively. Wet deposition was only collected in Wanzhou, where the annual wet deposition of NO3-and NH4+was 4.5 and 15.7 kg N ha-1yr-1, respectively. The total wet plus dry deposition was 28.7 kg N ha-1yr-1in Wanzhou with 72.2% from reduced nitrogen. Therefore, controlling NH3emissions from agricultural, traffic, waste containers and sewage system sources would be effective to reduce the total nitrogen deposition in the Sichuan Basin area.
Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China.
Huanbo
H
Wang
Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; CAS Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
Fumo
F
Yang
Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China. Electronic address: shigm@cigit.ac.cn.
Guangming
G
Shi
Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China.
Mi
M
Tian
Air Quality Research Division, Science and Technology Branch, Environment and Climate Change Canada, Toronto, M3H 5T4, Canada.
Leiming
L
Zhang
Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir, Chongqing Three Gorges University, Chongqing, 404100, China.
Liuyi
L
Zhang
Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir, Chongqing Three Gorges University, Chongqing, 404100, China.
Chuan
C
Fu
D000383:Agriculture; D000393:Air Pollutants / Q000032:analysis*; D001272:Atmosphere / Q000737:chemistry; D002681:China; D002947:Cities; D016000:Cluster Analysis; D017753:Ecosystem; D004784:Environmental Monitoring; D006801:Humans; D009584:Nitrogen / Q000032:analysis*; D017672:Nitrogen Compounds / Q000032:analysis*; D012621:Seasons; D018505:Waste Management
D000393:Air Pollutants; D017672:Nitrogen Compounds; D009584:Nitrogen
Atmospheric nitrogen; Dry and wet deposition; Inferential deposition model; Oxidized nitrogen; Reduced nitrogen