atmospheric particulate matter: chemical composition and basics of concentration estimation
DESCRIPTION
Atmospheric Particulate Matter: Chemical Composition and Basics of Concentration Estimation. Mike Bergin, Ted Russell, Jim Mullholland, Sangil Lee. CEE 6319: Air Module. Overview. Week 1 (April 8) Lecture (Bergin) Background (effects, extent of problem, PM characteristics, etc.) - PowerPoint PPT PresentationTRANSCRIPT
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Atmospheric Particulate Matter: Atmospheric Particulate Matter: Chemical Composition and Basics of Chemical Composition and Basics of
Concentration EstimationConcentration Estimation
Mike Bergin, Ted Russell, Jim Mullholland, Sangil Mike Bergin, Ted Russell, Jim Mullholland, Sangil LeeLee
CEE 6319: Air ModuleCEE 6319: Air Module
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Overview
• Week 1 (April 8)– Lecture (Bergin)
• Background (effects, extent of problem, PM characteristics, etc.)• An overview of filter based sampling
• Week 2 (April 11 -15)– Lecture (Bergin)
• Nut and bolts of atmospheric particulate measurements• Detection limit determination
– Lab (Lee)• Begin sampling ambient particulate matter on EST roof
• Week 3 (April 17-22)– Lab (Lee)
• Finish sampling• Laboratory analyses (mass, ions, carbon, select elements)
• Week 4 (April 29)• Lab due on last day of classes
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P
Potential Gas/Particle Interactions at a Filter Surface
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PM2.5 Mass from Teflon Filter Gravimetry
Equilibration of Teflon filter samples in Class 1000 Clean Room
[PM] < 1000/scf, T = 21 +-0.5 oC, RH = 33 +-3 %
Mettler Toledo MT5 Electronic Micro-Balance
Exp. DL = 1.2 +-0.02 g; P = +- 0.4 % @ 1 g; A = +-0.001 % {1-500 mg}
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PM2.5 NAAQS will also impact many smaller cities
Monitors at which the 1999 annual average [PM2.5] exceeds (yellow and red) the 15 g/m3 annual average PM2.5 NAAQS.
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Annual Average PM2.5 in Urban Areas, 2002
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PM2.5 Concentrations Across the PRD
•Concentrations at all sites above annual U.S NAAQS
•Organic carbon and sulfate are the dominant species
•Guangzhou appears to be major source of PM
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EC2.1%
OC9.5%
Unidentif ied20%
Trace Metals1.4%
Crustal Material51%
NH4+
0.4%Cl-
0.4%
SO42-
3.4%
NO3-
0.8%
CO32-
11.1%
SO42-
17%NO3
-
5.8%
Cl-
0.6%
NH4+
6.2%
Unidentif ied-12.9%
Crustal Material28.7%
Trace Metals0.7%
OC41%
EC13%
Aerosol Chemical Composition Measured in Yulin, China
Dust
Anthropogenic Pollution
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Emissions/AQ Trends: Primary PM2.5
AQ
Emissions
Sources (2001)
Potential Risks and Effects• Heart (arrhythmias, attacks)
• Respiratory (asthma, bronchitis)
• Among elderly and young• Vegetation (ecosystem)
• Buildings, Materials• Visibility
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Other (Inorganic) Secondary PM Formation
Secondary formation is a function of many factors including: concentrations of precursors, other gaseous reactive species (e.g., O3, OH), atmospheric conditions, and cloud or fog droplet interactions.
Gas-to-particle conversion (oxidation)
SO2(g) HOSO3 H2SO4 + 2NH3 (NH4)2SO4
NOx(g) HNO3 + NH3 NH4NO3
Heterogeneous reactions
(R7)
R6)(
R5)(
)4R()(
2422
123
233
322
2222
SOOSO
SOHHSO
HSOHOHSO
OHSOOHgSO
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Emissions/AQ Trends: SO2
AQ
Emissions Sources (2001)
Potential Risks and Effects• Breathing impairment
• Respiratory, cardiovascular {PM}• Precursor for PM
•Acidification (soils, waters)• Corrosion (bldgs, monuments)
• Visibility
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SO2 SO4= in Greater Atlanta for July 2001
34.4
34.2
34.0
33.8
33.6
33.4
33.2
33.0
32.8
32.6
32.4
-85.0 -84.5 -84.0 -83.5 -83.0 -82.5 -82.0
Atlanta
FAQS ASACA sites significant point sources point sources w/ CO:NOx > 1
20x20 km
Griffin
Macon
Augusta
Columbus
N
E
S
W6 12
SO2*3 (ppbv)
SO4= (µgm-3)
WS*2 (m/s)
WD (%)
N
E
S
W6 12
SO2*2 (ppbv)
WS*2 (m/s)
WD (%)
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Emissions/AQ Trends: CO
AQ
Emissions
Sources (2001)
Potential Risks and Effects
• Blood-O2 deficiency
• Cardiovascular (angina pectoris)• Visual, neurological impairment
• Role in P(O3) via HOx cycle (slow)
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Emissions/AQ Trends: NOx (NO+NO2)
AQ
Emissions
Sources (2001)
Potential Risks and Effects• Airway, lung function
• Respiratory illness, infection• Precursor for O3 and PM
•Acid deposition (nutrient loss)• Eutrophication (algae bloom)
• Visibility
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Measuring ions using ion chromatography
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An example Chromatogram (Anions)
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An example Chromatogram (Cations)
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Measuring Elemental and Organic Carbon (EC/OC)
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The Sunset Lab Instrument
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Thermal Evolution Thermalgram
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Estimating Mass Closure
To estimate the mass concentration based on chemical composition:
MT = ∑ions + ∑elements + ∑crustal + ∑carbon
= ∑ions measured +
∑Al*1.9 (Al2O3) + Si*2.1 (SiO2) +Fe*1.4 (Fe2O3)
+ Elemental Carbon (EC) +Organic Carbon (OC)*1.4
Mass Closure = ΔM = Measured Mass- Estimated Mass
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Uncertainty Estimation
Root Sum Square Method:
For Example Function:
X=ABm/Cn
2C
2B
2Ax
CnU
BmU
AU
XU
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A Simple Example
Mass Concentration = Mass on Filter (ΔM) / Air Volume (V)
M = ΔM / V
ΔM = 100 ug ± 10 ug; V = 1.0 m3 ± 0.1 m3
%140.11.0
10010
MU 22m