Characterization of individual aerosol particles collected during haze episodes in Taiyuan
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Characterization of individual aerosol particles collected during haze episodes in Taiyuan
name : Wu Limajor : Applied Chemistry
tutor : Geng Hong
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Introduction
An atmospheric phenomenon that leads to low visibility.
definition Haze
infl
uen
ces
Visibility Cloud formation Public health Global climate
origin
Continuous ecnomic growth Increased cosumption of fossil fuels
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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
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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.
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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 ele
ments• Providing transformation information
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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
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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
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Data measurement and analysis
1. 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 evalu
ated by a nonlinear least-squares fitting using the AXIL programme4. A Monte Carlo simulation with successive approximation is used for q
uantification5. The "expert system" is used to determine the formular concentrations
and particle group distributions
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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
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X-ray spectra and atomic concentratrations of EC and OC
back
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Typical SEM image of aerosol particles
collected in Taiyuan
#1 OC
#2 EC
#3 aluminosilicate
#4 OC
#5 CaCO3
#6 SiO2
#7 CaCO3#8 OC
#9 reacted CaCO3
#10 reacted CaCO3
#11 (NH4)2SO4
#12 NH4HSO4
#13 K-rich
#14 K-rich
back
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Preliminary statistics
0%
20%
40%
60%
80%
100%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21样品
相对
丰度
EC OC 初级矿物尘 反应矿物尘 Fe富 颗粒 K富 颗粒 二次颗粒 反应海盐 其他颗粒
0%
20%
40%
60%
80%
100%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21样品
相对
丰度
EC OC 初级矿物尘 反应矿物尘 Fe富 颗粒 K富 颗粒 二次颗粒 反应海盐 其他颗粒
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
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Preliminary statistics
0%
20%
40%
60%
80%
100%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21样品
相对
丰度
EC OC 初级矿物尘 反应矿物尘 Fe富 颗粒 K富 颗粒 二次颗粒 反应海盐 其他颗粒
Relative abundances of different particle types for the 21 sets of samples in stage 6
0%
20%
40%
60%
80%
100%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21样品
相对
丰度
EC OC 初级矿物尘 反应矿物尘 Fe富 颗粒 K富 颗粒 二次颗粒 反应海盐 其他颗粒
Relative abundances of different particle types for the 21 sets of samples in stage 7
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Thank you !
Looking forward to your suggestions!