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

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

P

Potential Gas/Particle Interactions at a Filter Surface

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}

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.

Annual Average PM2.5 in Urban Areas, 2002

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

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

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

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

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

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 (%)

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)

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

Measuring ions using ion chromatography

An example Chromatogram (Anions)

An example Chromatogram (Cations)

Measuring Elemental and Organic Carbon (EC/OC)

The Sunset Lab Instrument

Thermal Evolution Thermalgram

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

Uncertainty Estimation

Root Sum Square Method:

For Example Function:

X=ABm/Cn

2C

2B

2Ax

CnU

BmU

AU

XU

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