期刊
ATMOSPHERIC RESEARCH
卷 174, 期 -, 页码 62-69出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.atmosres.2016.02.003
关键词
PM2.5; Beijing; Haze; Aerosol chemical compositions
资金
- CAS [Y12901FEA2, Y225019EA2]
- Natural Science Foundation for the Youth [Y41101E1A1]
- State Key Joint Laboratory of Environment Simulation and Pollution Control [15K05ESPCP]
To investigate the chemical properties of PM2.5 and put forward reasonable control measures, daily samples of PM2.5 were collected at an urban site in Beijing from August 4 to September 3 of 2012 using two 2-channel samplers. Chemical analysis was conducted for eight water soluble inorganic ions (WSII, including Na+, NH4+, K+, Mg2+, Ca2+, Cl-, and SO4-), organic carbon (OC) and elementary carbon (EC). PM2.5 concentrations ranged from 8.8 to 218.6 mu g m(-3), with an average concentration of 80.6 +/- 573 mu g m(-3).WSII, the most dominant PM2.5 constituents contributing 60 +/- 18% of its mass, ranged from 3.1 to 172.2 mu m m(-3). SO42-, NO3-, and NH4+ dominated WSII (90 +/- 28%) and their concentrations were 1.3-105.7 mu g m(-3), 0.5-52.7 mu g m(-3) and 0.3-33.5 mu g m(-3), respectively. The concentrations of OC and EC were 3.0-28.8 mu gC m(-3) and 0.8-7.4 mu gC m(-3) constituting 17.6% and 4.9% of PM2.5, respectively. Three serious pollution episodes (haze days) occurred during the campaign. PM2.5 and its chemical species showed substantial increases during haze episodes. The greater enhancement factors for SO42- (4.5), NO3- (4.0), and NH4+ (4.2) during haze days compared to non-haze days were obtained, suggesting that these secondary inorganic ions play important roles in the formation of haze. The average ratio of NO3-/SO42- was 0.52. Ion balance calculations showed that PM2.5 samples were acidic during haze periods and close to neutral during non-haze days. Correlation analysis between the major ions was conducted and the results suggested that the main forms of NH4+ might be (NH4)(2)SO4. In addition, the variations between haze days and non-haze days for OC, EC, and the ratio of OC/EC were discussed. (C) 2016 Elsevier B.V. All rights reserved.
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