气候变化领域集成服务门户(CCPortal): Air quality in the eastern United States and Eastern Canada for 1990-2015: 25 years of change in response to emission reductions of SO2 and NOx in the region

CCPortal

DOI	10.5194/acp-20-3107-2020
	Air quality in the eastern United States and Eastern Canada for 1990-2015: 25 years of change in response to emission reductions of SO2 and NOx in the region
	Feng J.; Chan E.; Vet R.
发表日期	2020
ISSN	16807316
起始页码	3107
结束页码	3134
卷号	20 期号:5
英文摘要	SO2 and NOx are precursors to form sulfate, nitrate, and ammonium particles in the air, which account for more than 50% of PM2.5 mass in the eastern US (Bell et al., 2007) and are dominant components of PM2.5 during many smog events (Dabek-Zlotorzynska et al., 2011). H2SO4 and HNO3, formed from the oxidation of SO2 and NOx, respectively, are the main sources of acid deposition through wet and dry depositions. NOx is also a precursor to the formation of tropospheric O3, which is an important atmospheric oxidant and is also essential for the formation of other atmospheric oxidants, such as OH and H2O2. In the past 26 years from 1990 to 2015, emissions of SO2 and NOx in the US were significantly reduced from 23.1 and 25.2 million t yr1 in 1990 to 3.7 and 11.5 million t yr1 in 2015, respectively. In Canada, SO2and NOx were reduced by 63% and 33% from 1990 to 2014. In response to the significant reductions of SO2and NOx emissions, air quality in the eastern US and Eastern Canada improved tremendously during 1990-2015. In this study, we analyzed surface air concentrations of SO24 , NO3, NHC4, HNO3, and SO2measured weekly by the Clean Air Status and Trends Network (CASTNET) in the US and measured daily from the Canadian Air and Precipitation Monitoring Network (CAPMoN) in Canada to reveal the temporal and spatial changes in each species during the 25-year period. For the whole eastern US and Eastern Canada, the annual mean concentrations of SO24 , NO3 , NHC4, HNO3, SO2, and TNO3 (NO3 CHNO3, expressed as the mass of equivalent NO3) were reduced by 73.3 %, 29.1 %, 67.4 %, 65.8 %, 87.6 %, and 52.6 %, respectively, from 1990 to 2015. In terms of percentage, the reductions of all species except NO3 were spatially uniform. The reductions of SO2and HNO3 were similar in the warm season (May-October) and the cold season (November-April), and the reductions of SO24, NO3, and NHC4 were more significant in the warm season than in the cold season. The reductions of SO24 and SO2mainly occurred in 1990-1995 and 2007-2015 during the warm season and in 1990-1995 and 2005-2015 during the cold season. The reduction of NO3 mainly occurred in the Midwest after 2000. Other than in the Midwest, NO3 exhibited very little change during the cold season for the period. The reduction of NHC 4 generally followed the reduction trend of SO24 ; especially after 2000, the temporal trend of NHC4 was almost identical to that of SO24 . The ratio of S in SO24 to total S in SO24 plus SO2, as well as the ratio of NO3 to TNO3 increased by more than 50% during the period. This indicates that a notable change in regional chemistry took place from the beginning to the end of the period, with a higher percentage of SO2being oxidized to SO24 and a higher percentage of HNO3 being neutralized to NH4NO3 near the end of the period. © 2020. This work is distributed under the Creative Commons Attribution 4.0 License.
关键词	air quality atmospheric pollution concentration (composition)deposition emission control nitrogen oxides oxidation particulate matter sulfur dioxide Canada United States
语种	英语
来源机构	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/132170
推荐引用方式 GB/T 7714	Feng J.,Chan E.,Vet R.. Air quality in the eastern United States and Eastern Canada for 1990-2015: 25 years of change in response to emission reductions of SO2 and NOx in the region[J]. Atmospheric Chemistry and Physics,2020,20(5).
APA	Feng J.,Chan E.,&Vet R..(2020).Air quality in the eastern United States and Eastern Canada for 1990-2015: 25 years of change in response to emission reductions of SO2 and NOx in the region.,20(5).
MLA	Feng J.,et al."Air quality in the eastern United States and Eastern Canada for 1990-2015: 25 years of change in response to emission reductions of SO2 and NOx in the region".20.5(2020).