Measurements of Fine Aerosol Inorganic Composition

Chris Hennigan, Scott Sandholm, Rodney WeberMarch 2005

Method: PILS-IC

Drains Debubbler

Transport Liq. Flow(LiF) aq.

Drain Drain

Anion Cation

Drain

IonChromatographs

Vac. Pump

Denuders(Gas Removal)

Multi-channel activatedCarbon (MAST)

Na2CO

3 & H

3PO

4

Particle SizeSelector

(PM1)

water

Na2CO3, Citric Acid

14.5 L/min sampling rate

Species Measured (Detection Limit µg/m3):Na+ (0.2), NH4

+ (0.2), K+ (0.5), Ca2+ (0.2), Mg2+ (0.1)Cl- (0.02), SO4

2- (0.03), NO3- (0.04)

Sample Rate: 2.4 minutes

Fine Particle (PM1.0) INTEX-NA Concentrations

Mean Standard Dev. Min (LOD/2) MaxNa+ 0.11 0.15 0.10 4.35NH4

+ 0.92 1.33 0.10 8.28Ca2+ 0.11 0.14 0.10 4.15K+ 0.25 0.18 0.25 7.66Mg2+ 0.05 0.05 0.05 1.90Cl- 0.02 0.11 0.01 4.34NO3

- 0.09 0.26 0.02 2.90SO4

2- 1.38 2.39 0.02 19.35

All Data: µg/m3 at 20°C 1 atm

• Na+, Ca2+, K+, Mg2+, Cl- all near/below LOD throughout mission• SO4

2- dominate ionic component

NO3 Spatial Distribution (DC-8)

7000

6000

5000

4000

3000

2000

1000

Alti

tude

(m)

2.52.01.51.00.50.0Nitrate (ug/m3

)

60

50

40

30

-140 -120 -100 -80 -60 -40

2.52.01.51.00.5

Nitrate (ug/m3)

SO4= Spatial Distribution (DC-8)

60

50

40

30

-140 -120 -100 -80 -60 -40

151050

Sulfate (ug/m3)

7000

6000

5000

4000

3000

2000

1000

Alti

tude

(m)

151050Sulfate (ug/m3

)

NH4 Spatial Distribution (DC-8)

Ammonium data for 9 of 18 flights

7000

6000

5000

4000

3000

2000

1000

Alti

tude

(m)

86420Ammonium (ug/m3

)

60

50

40

30

-140 -120 -100 -80 -60 -40

8642

Ammonium (ug/m3)

Aerosol apparent acidity: (NH4)2SO4

0.4

0.3

0.2

0.1

0.0

NH

4 (µ

Eq

m-3

)

0.40.30.20.10.0

NO3 + SO4 (µEq m-3)

1

1

fit forced thru 0Slope = 1.16R2 = 0.76

SO4:– dominant ionic species– highest in 0-2 km alt.– High scattering, vol.

7000

6000

5000

4000

3000

2000

1000

Alti

tude

(m)

20151050Sulfate (ug/m3)

10

8

6

4

2

Alti

tude

(km

)

4003002001000450nm submicron scat. (Mm-1)

10

8

6

4

2A

ltitu

de (k

m)

1008060402000.3 - 2 um Volume (um3/cm3)

400

NOAA P3 Results: Similar but Different– SO4

= dominates inorganic – Highest at low altitudes

6

5

4

3

2

1

0

0.01 0.1 1 10 100

WSOC/Sulfate, µgC/µgSO 4=

6

5

4

3

2

1

0

3020100

Sulfate, µg m-3

6

5

4

3

2

1

0

2520151050

WSOC, µgC m-3

NOAA P3: ITCT 2K4

NOAA P3 Results: Similar but Different– Not as neutralized

NASA DC-8 NOAA P3

0.4

0.3

0.2

0.1

0.0

NH

4 (µ

Eq

m-3

)

0.40.30.20.10.0

NO3 + SO4 (µEq m-3)

1

1

fit forced thru 0Slope = 1.16R2 = 0.76

0.6

0.5

0.4

0.3

0.2

0.1

0.0

NH

4 (µ

Eq

m-3

)

0.60.50.40.30.20.10.0

NO3 + SO4 (µEq m -3)

Fit Forced thru 0slope = 0.66R2 = 0.75

NOAA P3: More Detailed Studies of Specific Plumes

37

36

35

34

33

32

-88 -86 -84 -82 -80

100

80

60

40

20

0

SO

2 sources

2.4

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

NH

4/SO

4 molar

5:00 PM8/15/04

6:00 PM 7:00 PM 8:00 PM

5000

4000

3000

2000

1000

0

Altitude (m

)

14

12

10

8

6

4

2

0

SO

2 (p

pb)

15

10

5

0

Sul

fate

(ug/

m3 )

alt SO4 SO2 NH4_SO4_ratio

X•

0.4

0.3

0.2

0.1

Con

cent

ratio

n, E

qu/m

3

3:30 PM7/20/04

4:00 PM 4:30 PM

6000

5000

4000

3000

2000

1000

Altitude, m

NH4

SO4

Alt.

Weber et al. JAWMA 2003

Fine Particle SO4= Source ?

A Near-BL Analysis (z < 2.2 km)

• Analyze legs below 2.2 km alt.

• Each BL pass = 1 data point

• Minimum 3 SO4=

measurements per pass, ~ constant altitude

• Total of 79 BL passes analyzed (5 excluded)

7000

6000

5000

4000

3000

2000

1000A

ltitu

de (m

)

20151050Sulfate (ug/m3)

2.2 km

1999 SO2 Emissions (tons/yr)

50

45

40

35

30

25

-120 -110 -100 -90 -80 -70

200

150

100

50

0

x103

Source: EPA National Emissions Inventory 1999, courtesy of NOAA

**Only point sources with > 500 tons/yr SO2 emissions plotted

Ohio River Valley23% of all SO2 emissions

NOAA HYSPLIT3-5 day back trajectory for each DC-8 BL pass

60

50

40

30

-120 -100 -80 -60 -40

flight pass back trajectory

Back Trajectories Analysis for DC-8 Legs, Alt. < 2.3 km

60 Non-ORV79 BL passes analyzed(67 are East of Miss. R.) 19 ORV, 25%

60

50

40

30

-120 -100 -80 -60 -40

Non-ORV pass ORV pass

ORV vs. Non-ORV results

0

1

2

3

4

5

6

ORV Non-ORV

Avg. SO4

=

(µg/m3)

Avg. Total SSO4

= + SO2(µgS/m3)

AverageSO

4=/(SO

4=+SO

2)

(molar ratio)

5.58

1.67

4.69

2.08

0.40.11

Distribution of sulfate concentration below 2.2 km

1.0

0.8

0.6

0.4

0.2

0.0Frac

tion

of P

asse

s w

/ Hig

her S

O4

14121086420Average SO4 (ug/m3)

ORV

Non-ORV

ORV Non-ORV

Altitude vs. SO4: Ohio RV vs. Non-Ohio RV

7000

6000

5000

4000

3000

2000

1000

Alti

tude

(m)

20151050Sulfate (ug/m3

)

Non-ORV ORV

A Unique Compound Observed During Azores Intercomparison Flight 7/28/04

Unknown Compound• Comes out at phosphate• Not MS

1.5

1.0

0.5

Con

cent

ratio

n (u

g/m

3 )

4:15 PM7/28/04

4:30 PM 4:45 PM 5:00 PM 5:15 PM

7000

6000

5000

4000

3000

2000

1000

Altitude (m

)

PILS sulfate PILS unknown altitude

SO4=: AMS significantly higher than PILS; generally not observed

Unknown Compound Correlates with "Fine"-Particle Volume and DMS

1.5

1.0

0.5

Ion

conc

entra

tion

(ug/

m3 )

4:15 PM7/28/04

4:30 PM 4:45 PM 5:00 PM 5:15 PM

7

6

5

4

3

2

1

0

0.2 - 3 um V

olume (um

3/cm3)

PILS sulfate PILS unknown 0.3 - 2 um Volume

1.5

1.0

0.5

Ion

conc

entra

tion

(ug/

m3 )

4:15 PM7/28/04

4:30 PM 4:45 PM 5:00 PM 5:15 PM

25

20

15

10

5

DM

S (pptv)

PILS sulfate PILS unknown DMS

Summary

• Sulfate: dominant fine inorganic aerosol species measured in summer 2004 INTEX-NA (and NEAQS-ITCT 2004) study– Highest at low altitudes – DC-8 most often (NH4)2SO4 (neutralized), not observed on

NOAA P3

• Air masses that passed through the Ohio River region contained, on average, 3 times as much SO4

= (twice as much total S) as those that did not, (observed widely east of Miss. R.).

• Unidentified "fine particle" constituent observed in marine BL– Concentrations could be higher than SO4

2-.– May be some marine sulfur compound.