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Characterization of individual aerosol particles collected during haze episodes in Taiyuan

Characterization of individual aerosol particles collected during haze episodes in Taiyuan. name : Wu Li major : Applied Chemistry tutor : Geng Hong. Introduction. An atmospheric phenomenon that leads to low visibility. Haze. definition. origin. influences. Continuous ecnomic growth

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Characterization of individual aerosol particles collected during haze episodes in Taiyuan

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  1. Characterization of individual aerosol particles collected during haze episodes in Taiyuan name : Wu Li major : Applied Chemistry tutor : Geng Hong

  2. Introduction An atmospheric phenomenon that leads to low visibility. Haze definition origin influences Continuous ecnomic growth Increased cosumption of fossil fuels Visibility Cloud formation Public health Global climate

  3. Objective • Identify the particle types • Analyse the Chemical compositons and mophologies of particles • Compare the relative abundance of particle types • Investigate transformation information on particles during haze episodes

  4. Quantitative energy-dispersive electron probe X-ray microanalysisLow-Z particle EPMA Quantitative energy-dispersive electron probe X-ray microanalysis(ED-EPMA) method, called low-Z particle EPMA,is based on scanning electron microscopy(SEM) coupled with an ultra-thin window eneryg-dispersive X-ray detector.

  5. Quantitative energy-dispersive electron probe X-ray microanalysisLow-Z particle EPMA Advantages: • Short duration time of sampling • A high degree of quantification • Detecting the mophology and constituent elements • Providing transformation information

  6. Sampling date and site 2011.12.30 4_PM to 2012.1.3 8_AM (a) a normal sunny day (b) a typical haze day

  7. Sampling Instrument Name:The modified seven-stage MAY cascade impactor Flow rate: 20L·min-1 The aerodynamic diameters for stages 1-7: >16µm, 16-8µm, 8-4µm, 4-2µm, 2-1µm, 1-0.5µm, 0.5-0.25µm

  8. Data measurement and analysis • SEM-EDX (Scanning Electron Microscopy – Energy Dispersive X-ray Spectrometer) Individual Particle Analysis shape and size : secondary electron images chemical compositions:X-ray spectra 2. Ultra-thin window EDX for low-Z elements detection (e.g., C, N, O, F) 3. The net characteristic X-ray intensities of chemical elements are evaluated by a nonlinear least-squares fitting using the AXIL programme 4. A Monte Carlo simulation with successive approximation is used for quantification 5. The "expert system" is used to determine the formular concentrations and particle group distributions

  9. Classification • Organic Carbon(OC)~~#1,#4,#8 • Elemental Carbon(EC)~~#2 • Mineral Dust(CaCO3、SiO2、aluminosilicates)~~ #3,#5,#6,#7 • Reacted Mineral Dust(reacted CaCO3)~~#9,#10 • (NH4)2SO4/NH4HSO4—containing~~#11,#12 • K—containing~~#13,#14

  10. X-ray spectra and atomic concentratrations of EC and OC back

  11. #7 CaCO3 #8 OC Typical SEM image of aerosol particles collected in Taiyuan #14 K-rich #4 OC #13 K-rich #9 reacted CaCO3 #2 EC #12 NH4HSO4 #11 (NH4)2SO4 #3 aluminosilicate #6 SiO2 #10 reacted CaCO3 #5 CaCO3 #1 OC back

  12. Preliminary statistics Relative abundances of different particle types for the 21 sets of samples in stage 4 Relative abundances of different particle types for the 21 sets of samples in stage 5

  13. Preliminary statistics Relative abundances of different particle types for the 21 sets of samples in stage 6 Relative abundances of different particle types for the 21 sets of samples in stage 7

  14. Thank you ! Looking forward to your suggestions!

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