Aerosol pollution in China

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Aerosol pollution in China
Min HU State Key Joint Laboratory of
Environmental Simulation and Pollution Control,
College of Environmental Sciences and
Engineering, Peking University Email
minhu_at_pku.edu.cn

• What is aerosol?
• What does aerosol look like?
• How big is aerosol?

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Aerosol pollution in China

• PM is dominant pollution in the cities of China.
• Fine particle is major fraction of PM10,
  deteriorated air quality and caused poor
  visibility
• More secondary composition (sulfate, nitrate,
  ammonium, Secondary organic compounds) in PM2.5
• Difficult to control (precursors, transport,
  transformation, mechanism, regional problem)
• Hygroscopic, grow up, CCN, climate change
• Hazardous PAHs EC from primary combustion
  process, harmful to human health

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Microscopic Pictures of Airborne Particles
Particles fall into two size categories 1.Coarse
Particles greater than 2.5 micrometers
and less than 10 micrometers. (These
particles usually deposit out of the air
close to their source.) 2. Fine Particles
2.5 micrometers and smaller (These
particles can stay suspended for weeks and
are transported far from their source.)
(1) Primary natural (biogenic) anthropoginic
(2)Secondary
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Metallurgy ????(PM1)
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Morphological and Chemical Characteristics
C-soot
Si-Al-O
NaCl (SOLAS)
Ca-O
Fe-O
Na-S-O
Fly ash Si-Al-Ca

• Complex and heterogeneous
• Some particles have euhedral morphologies
• more are amorphous/ irregularly shaped.
• Particles derived from anthropogenic emissions
  are usually sphere.

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Morphological and Chemical Characteristics
Si-O
Fe-Si-O
Al-Si-K
Fly ash Fe-Si-O
Biogenic Organic (PRD)
K-S
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Chemical Characteristics more soot in Beijing
Soot aggregates
Soot shows discontinuous onion-like structure of
graphitic layers
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Highlight 1Aerosol Sources is complex in China

• Mineral Dust
• Dust storm
• Road dust
• Fugitive dust (unpaved road, construction, soil)
• Combustion process
• Stationary like power plant, industry
• Vehicle
• Biomass burning
• Industry
• Cooking emission
• Natural sources sea salt, biogenic
• Secondary process sulfate, nitrate, ammonium,
  secondary organic aerosol (SOA)

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Nucleation Mode
Aitken Mode
Accumulation Mode
Coarse Mode
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Aerosol impact on air pollution
problems Definition solid or liquid small
bodies which have a residence time in air

• Local air pollution
• aerosols affect human health
• aerosols reduce visibility

• Regional air pollution
• aerosols contribute to acid deposition, affecting
  forests and lakes
• aerosols contribute to eutrophication, affecting
  water quality
• aerosol influence photochemistry and ozone
  production

• Global air pollution
• aerosols reflect solar light and hence influence
  climatic change
• aerosols catalyze stratospheric ozone loss /
  Antarctic ozone hole

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Aerosol size-concentration-characteristic-effect

• Aerosol is everywhere around us
• Concentrations
• massTSP, PM10, PM2.5
• numberup to 105/cm3
• surface
• volume
• size4-5 magnitudes,3nm-100?m?
• Chemical compositions
• Cover most chemical elements
• ?g/m3-ng/m3 3-5 magnitudes
• Integrated multi-instruments, and method to
  measure every aspects of aerosol
• QA/QC From TSP-PM10-PM2.5-PM1.0-ultrafine

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Highlight 2 Concentration level is quite high in
China
Number Conc. 3?104?1.6 ?104 cm-3 Surface
Conc. 1.4?103?1.0 ?103 mm2cm-3 Volume Conc. 90?70
mm3cm-3 PM10 Mass Conc. 153mg/m3
PV1/PV10 75
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Organics become major fraction in PM2.5
Data of Beijing and Guangzhou, 2000
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Beijing API39(I) Clear day
Highlight 3 Regional pollution impact on air
quality
Beijing API124(III1) Slight polluted day
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http//www.arl.noaa.gov/ready
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Beijing
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Tianjin
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HeBei
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Oct. 6, 2004 from Jietai Mao, Chengcai Li
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Oct. 7, 2004 from Jietai Mao, Chengcai Li
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Oct. 8, 2004 from Jietai Mao, Chengcai Li
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Oct. 9, 2004 from Jietai Mao, Chengcai Li
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Highlight 4 Organics become major fraction in
PM2.5, POC from combustion process and biogenic
VOC, SOC has to be paid more attention
Data of Beijing and Guangzhou, 2000
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Upper estimated SOC in four seasons
SOC concentrationSummer gt Fall gt Spring
Winter SOC/OCSummer gt Spring gt Fall gt Winter
Winter Spring FallPOC is major fraction of OC
SummerSOC can be comparable with POC OC in
Beijing PM2.5 mainly from primary emission.
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Highlight 5 Frequency of New Particle Formation
events
40 spring
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Classification of New Particle Formation Events
Wu et al., JGR,2007
Clean event
Polluted event
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New Particle Formation
Beijing Urban2004
Guangzhou Urban2004
Yellow Sea2005
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Summary and future work

• Mega-city, or PRD, YRD increasing population,
  vehicles, expansion and economic development can
  be a driving forcing of air pollution.
• Fine particle characters a secondary and regional
  problem.
• Transport and transformation of primary and
  gaseous precursors is necessary to understand
  regional air pollution.
• Interaction of aerosol pollution between big city
  and surroundings
• Nucleation mechanism of new particle, and
  possible chemical composition of new particles
  will help to understand the evolution of fine
  particle
• Health effect of fine and ultrafine particles

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Thank you for your attentions!

• Your comments are welcome!