Sources of Primary and Secondary Particles in the Houston Area in 2006

Objectives•Examine relative importance of primary and secondary aerosol sources•Evaluate contribution from Parish power plant and industrial emissions•Compare with TexAQS 2000 data

Charles Brock, Adam Wollny, Rebecca Washenfelder, Ann Middlebrook, Roya Bahreini, Ryan Spackman, Shuka Schwarz, John Holloway, Jeff Peischl, Tom

Ryerson, Andy Neuman, John Nowak, Joost de Gouw, Carsten Warneke, Michael Trainer, Andreas Stohl, Tahllee Baynard, and others. . ..

Aerosol Measurements on the NOAA P-3Particle size distributions, .005-8 µm, 1 sec.• Calculate integrated number and volume (proportional to

mass), uncertainties in integrated volume ~25%

Aerosol mass spectrometer, submicron sulfate, nitrate, ammonium, organics, 10 s

• mission absolute uncertainties ~50% (single-flight variability ~25%), good sensitivity

• Middlebrook talk, Bahreini poster

Particle-in-liquid sampler, submicron water-soluble organic (Hecobian poster)Single particle soot photometer (Spackman poster)Cavity ringdown extinction, f(rh), absorption (Baynard poster; Lack talk, Massoli poster for ship instruments)Actinic flux spectral radiometer (Stark poster)

Aerosol Measurements on the NOAA P-3Particle size distributions, .005-8 µm, 1 sec.• Calculate integrated number and volume (proportional to

mass), uncertainties in integrated volume ~25%

Aerosol mass spectrometer, submicron sulfate, nitrate, ammonium, organics, 10 s

• mission absolute uncertainties ~50% (single-flight variability ~25%), good sensitivity

• Middlebrook talk, Bahreini poster

Particle-in-liquid sampler, submicron water-soluble organic (Hecobian poster)Single particle soot photometer (Spackman poster)Cavity ringdown extinction, f(rh), absorption (Baynard poster; Lack talk, Massoli poster for ship instruments)Actinic flux spectral radiometer (Stark poster)

Not available in 2000 campaign

Focus on 27 September 2006:•High O3 day•Wind ~constant in direction, ~2x variable in speed•Many downwind transects•Source plumes ~separated•Qualitatively similar to days examined in 2000

30.6

30.4

30.2

30.0

29.8

29.6

29.4

29.2

29.0

latit

ude

-96.0 -95.5 -95.0 -94.5

longitude

31.0

30.8

30.6

30.4

30.2

30.0

29.8

29.6

latit

ude

-96.0 -95.5 -95.0 -94.5

longitude

28 August, 2000 27 September, 2006

Color & size proportional to particle volume. Scales differ.

Parish Industries

Parish

Industries

WindWind

30.6

30.4

30.2

30.0

29.8

29.6

29.4

29.2

29.0

latit

ude

-96.0 -95.5 -95.0 -94.5

longitude

31.0

30.8

30.6

30.4

30.2

30.0

29.8

29.6

latit

ude

-96.0 -95.5 -95.0 -94.5

longitude

Color & size proportional to particle volume. Scales differ.

But relative to August 2000. . .•Temperature cooler•Mixing less vigorous ↕ and ↔•Fewer photons•Background more variable, so uncertainties in Δ larger

28 August, 2000 27 September, 2006

Parish Industries

Parish

Industries

Background variability caused by recirculation of Houston/Beaumont area plume from previous day.

FLEXPART model transport footprint from 40,000 backtrajectories at aircraft location. Color proportional to backtrajectory residence time in

lowest 100 meters. Dots are MODIS fire hotspots.

Subtracting the background to isolate Parish and ship channel industrial plumes:

31.0

30.8

30.6

30.4

30.2

30.0

29.8

29.6

latit

ude

-96.0 -95.5 -95.0 -94.5

longitude

12

10

8

6

4

2

Part

icle

Vol

ume

and

SO2

-95.6 -95.4 -95.2 -95.0 -94.8 -94.6Longitude

Particle Volume µm3 cm-3

SO2 (ppbv)

Subjective and prone to error-->30% in volume?

Parish

IndustriesParish

Industries

27 September, 2006

Particle volume enhancements above background

Enhancements are <2 µm3cm-3 on average

Growth does not continue far downwind

Very little volume enhancement immediately downwind of sources

5

4

3

2

1

0

Particle Volume Enhancem

ent (µm3 cm

-3)

Parish

Industries

27 September, 2006

800

600

400

200

0

Part

icle

Vol

ume

Flux

(cm

3 s-1

)

86420Time Since Emission (hr)

Ship Channel Parish Power Plant Ship Channel 09/19 Ship Channel 09/21

Estimate flux of particle volume (mass) in ship channel and Parish power plant plumes

Uncertainties large due to background subtraction, wind speed at time of emission, PBL height (transport time uncertainties not shown)

Ship channel flux ~2x Parish flux

“Primary” mass emissions are small compared with secondary formation, but not negligible in ship channel area

Composition of particles from ship channel and Parish power plant

Ship channel particle mass is ~50% organic

Parish plume has no significant organic component

Black carbon flux from ship channel ~10 g s-1

(not shown), small but not negligible

1200

1000

800

600

400

200

0

Part

icle

Mas

s Fl

ux (g

s-1

)

86420Time Since Emission (hr)

Mass Fluxes from AMS Measurements Ship Channel Inorganic Ship Channel Organic Parish Inorganic Ship Channel Sulfate 09/19 Ship Channel Sulfate 09/21

Fluxes of SO2 from Ship Channel and Parish are comparable

3.5x1025

3.0

2.5

2.0

1.5

1.0

0.5

0.0

SO2 F

lux

(mol

ec s

-1)

86420Time Since Emission (hr)

Ship Channel Parish Power Plant

First Parish transect is in agreement with CEMS

Decline in flux with time may be caused by:•lower fluxes at time of emission (<10% var.)•dry deposition•g-p conversion (~20%)•background subtraction and other analysis biases

See Washenfelder et al. poster

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.00

Frac

tion

of P

lum

e S

as S

ulfa

te

86420Time Since Emission (hr)

Ship Channel Parish Power Plant

Oxidation of SO2 to form sulfate is comparable in Ship Channel and Parish plumes

Compare 2006 volume fluxes with 2000•Fluxes appear to be 5-10x lower in ship channel plume in 2006•Fluxes 2-4x lower even in Parish plume in 2006

Same Scale!Color & size proportional to particle volume, same dynamic range.

30.6

30.4

30.2

30.0

29.8

29.6

29.4

29.2

29.0

latit

ude

-96.0 -95.5 -95.0 -94.5

longitude

31.0

30.8

30.6

30.4

30.2

30.0

29.8

29.6

latit

ude

-96.0 -95.5 -95.0 -94.5

longitude

28 August, 2000 27 September, 2006

Compare sulfur oxidation in Parish plume2006 vs 2000

Oxidation is ~2x lower in Parish plume in 2006 than estimated in 2000

Remember SO2 flux decreases of ~2x also due to dry deposition or analysis biases.

Many possible causes:need careful evaluation of oxidative environment in 2006 and 2000

Not in time for RSS!

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Frac

tion

of P

lum

e Su

lfur i

n Pa

rtic

ulat

e Su

lfate

86420

Transport Time (hr)

27 September 2006 27& 28 August 2000

Small particles are rapidly formed downwind of sources, especially of SO2.

31.0

30.8

30.6

30.4

30.2

30.0

29.8

29.6

latit

ude

-96.0 -95.5 -95.0 -94.5

longitude

50x103

40

30

20

10

0

Particle number concentration (cm

-3)

27 September, 2006

Map color-coded by particle number concentration

Number may be correlated with health effects

As in 2000 data, number maximum occurs immediately downwind of SO2sources

Coagulation rapidly depletes number

Sources of Primary and Secondary Particles in the Houston Area in 2006

Conclusions•Secondary sources of particle mass dominate primary sources. “Primary” emissions (<20 minutes old) are not negligible in ship channel•On this day, the ship channel region produced fluxes of particle mass ~2x that of the Parish power plant•On this day, secondary mass formation ~2-10x lower than on comparable day during TexAQS 2000. Variability driven by meteorology, emissions, photochemistry, analysis biases? Need much more analysis for concrete results