Dr. Collins - College of Engineering

Experimental study of the production of PM2.5
in Southeast Texas clouds
Don Collins
Jill Matus
Nathan Taylor
Manny Salgado
Atmospheric Sciences Department and
Environmental Programs in Geosciences
Texas A&M University
1
Secondary PM formation pathways
H2O2
SO2 + OH …  H2SO4
SO2
VOC + OH …  SOA
VOC
OH 
OH 
(secondary organic aerosol)
H2O2
SO2
VOC
~80% SO2  SO4 (e.g., Barth et al., 2000)
??% VOC  SOA
2
Frequent cumulus field in SE Texas
Terra MODIS image from 8/5/14
3
Evidence of aqueous sulfate and SOA production
Wonaschuetz, A., A. Sorooshian, B. Ervens, P. Y. Chuang, G. Feingold, S. M. Murphy, J. de Gouw, C. Warneke, and
H. H. Jonsson (2012), Aerosol and gas re-distribution by shallow cumulus clouds: An investigation using airborne
measurements, J. Geophys. Res., 117, D17202, doi:10.1029/2012JD018089.
4
Uncertainty of in-cloud sulfate production rate
Zhou, W., D. S. Cohan, R. W. Pinder, J. A. Neuman, J. S. Holloway, J. Peischl, T. B. Ryerson, J. B. Nowak, F. Flocke
and W. G. Zheng (2012). "Observation and modeling of the evolution of Texas power plant plumes." Atmospheric
Chemistry and Physics 12(1): 455-468.
5
Significant, but uncertain, in-cloud production of SOA
6
Laboratory studies of in-cloud production
E.g., Carlton, A. G., Turpin, B. J., Altieri, K. E., Seitzinger, S., Reff, A., Lim, H. J., and Ervens, B.: Atmospheric oxalic
acid and SOA production from glyoxal: results of aqueous photooxidation experiments, Atmos. Environ., 41, 7588–7602,
2007.
7
Chamber studies of in-cloud production
Caffrey, P., et al. (2001), In-cloud oxidation of SO2 by O3 and H2O2: Cloud chamber measurements and modeling of
particle growth, J. Geophys. Res., 106(D21), 27587–27601,
8
1st generation captive aerosol chambers
9
2nd generation captive aerosol chambers
10
Formation of boundary layer clouds
11
Cloud cycle T and P profiles
26
24
o
T ( C)
22
20
18
16
14
1000
P (mbar)
950
900
850
800
750
0
10
20
30
Time (min)
40
50
60
12
Captive Aerosol Growth and Evolution (CAGE) chambers
13
CAGE chamber design
14
Controlled pressures within chamber layers
15
Controlled temperature within chamber
16
Chamber and platform rotation
17
Rotating drum technique developed for bioaerosol research
B. Asgharian & O. R. Moss (1992): Particle Suspension in a Rotating Drum Chamber When the Influence of Gravity and
Rotation are Both Significant, Aerosol Science and Technology, 17:4, 263-277
18
Experimental procedure
1. Flush chambers with zero, prescribed composition, ambient, or ambient +
perturbation flow
2. Inject one or more monodisperse particle population sizes
3. Allow gas phase photochemistry to produce representative distribution of soluble
species
4. Form cloud by simultaneously decreasing chamber pressure and circulation flow
temperature
5. Dissipate cloud and evaporate droplets by simultaneously increasing chamber
pressure and circulation flow temperature
6. Measure resulting change in particle size, hygroscopicity, and volatility with
SMPS and TDMA
19
Previous steps and next steps
To date:
• Improving software control and automation (mostly me)
• Improving chamber design and operation (mostly grad students)
To follow:
• First set of experiments to begin in coming days
20
Improving software control and automation
Control:
•
18 flow rates;
•
14 temperatures;
•
8 pressures;
•
5 humidities
Using:
•
46 electrically-actuated control, on/off,
and 3-way valves;
•
26 vacuum pumps, water pumps, and
blowers;
•
11 heaters and a variable temperature
chiller system;
•
12 data acquisition cards
21
Improving software control and automation
22
Pressure control during cloud cycle
Previously
Now
23
Improving chamber design and operation
24
Improving chamber design and operation
•
Replaced all flange gaskets
•
Redesigned seals around the 3 FEP Teflon cylinders
•
Built high concentration O3 generator
•
Filled chambers with several ppm O3
•
“Sniffed” using O3 analyzer
25
Improving chamber design and operation
•
Filled chamber with even higher concentration of ozone for ~day
•
Sampled air from various locations in the chambers and supporting systems
using a proton transfer reaction mass spectrometer (PTR-MS)
•
Constructed a Potential Aerosol Mass system (e.g., Kang et al., 2007) and again
sampled air from various locations.
26
Improving chamber design and operation
Filled chamber with even higher concentration of ozone for ~day
•
Sampled air from various locations in the chambers and supporting systems
using a proton transfer reaction mass spectrometer (PTR-MS)
•
Constructed a Potential Aerosol Mass system (e.g., Kang et al., 2007) and again
sampled air from various locations.
Signal
•
m/z
27
Improving chamber design and operation
•
Filled chamber with even higher concentration of ozone for ~day
•
Sampled air from various locations in the chambers and supporting systems
using a proton transfer reaction mass spectrometer (PTR-MS)
•
Constructed a Potential Aerosol Mass system (e.g., Kang et al., 2007) and again
sampled air from various locations.
From
Chamber
To
DMA
UV Bulb
O3
O3
OH∙
OH∙
O3
HO2∙
O3
Charcoal
Filters
N2
Sheath
Gas
OH∙
O3
OH∙
HO2∙
HO2∙
28
Improving chamber design and operation
•
Filled chamber with even higher concentration of ozone for ~day
•
Sampled air from various locations in the chambers and supporting systems
using a proton transfer reaction mass spectrometer (PTR-MS)
•
Constructed a Potential Aerosol Mass system (e.g., Kang et al., 2007) and again
sampled air from various locations.
o Identified the catalytic converter used in the zero air generation system as a
significant source. It has since been removed.
29
Planned experiments
∆𝑚𝑝
∆𝑥
∆𝑚𝑝
𝑜𝑟
∆𝑥
𝐴𝑚𝑏𝑖𝑒𝑛𝑡 𝑏𝑎𝑠𝑒𝑙𝑖𝑛𝑒
𝑃𝑟𝑒𝑠𝑐𝑟𝑖𝑏𝑒𝑑 𝑏𝑎𝑠𝑒𝑙𝑖𝑛𝑒
30
First steps and next steps
To date:
• Improving software control and automation (mostly me)
• Improving chamber design and operation (mostly grad students)
To follow:
• First set of experiments to begin in coming days
31
Extra slides
32
33
FEP layers and pressure differentials
34
Common approach to minimize losses - AIDA
35
Common approach to minimize losses - MINS
36
Airflow rotary unions
37
Preliminary test results
1400
1200
dN/d(log Dp)
1000
800
600
400
200
0
0.01
0.1
1
Particle Diameter (µm)
After Cloud Formation
Before Cloud Formation
38
39
40
ePTFE
0 ppb SO2
0 ppb SO2
1 cm
1 ppb SO2
J  D
1 ppb SO2


cm 2  2.4 1010 cm 3

  0.13
dx
s 
1cm

dnSO2
 5.2 10 15
mol
 5.2
cm 2 s
fmol
cm2 s
 
mol 
 6.02 10 23 



fmol
J    SO2   669 2
cm s ppbV

 669 10 15
mol
 669
cm 2 s

1 ppbV 

fmol
cm2 s
41
AACES response time
42
AACES O3 tracking
43
44
AACES particle retention
45
Objectives
46
AACES example experiment
0.14
Peak Dp (m)
1.5
0.12
0.11
1.4
particle size
growth factor
0.10
0.09
1.3
0.08
Growth Factor at peak D p
1.6
0.13
1.2
Soluble Mass (kg)
Insoluble Mass (kg)
-18
Per particle mass
1.5x10
1.0
0.5
0.0
21.4
21.6
21.8
22.0
22.2
22.4
Fractional day (June 21 - 22)
47
AACES example experiment
48
PM2.5 composition in SE Texas
Sulfate
Organic carbon
Ammonium
Russell, M. M., Allen, D. T., Collins, D. R., and Fraser, M. P., 2004. “Daily, seasonal and spatial trends in
PM2.5 mass and composition in Southeast Texas,” Aerosol Science and Technology, 38, Suppl. 1, pp 14-26
49
Signature of cloud processing on near-surface PM
Interstitial
CCN
50
Signature of cloud processing on near-surface PM
-3
dN/dlogDp (cm )
300
200
100
0
2
3
4
5
6 7 8 9
2
3
4
5
6 7
0.1
Dp (m)
Tomlinson, J. M., Li, R., and Collins, D. R., 2007. “Physical and chemical properties of the aerosol within the
southeastern Pacific marine boundary layer,” Journal of Geophysical Research – Atmospheres, 112 art No. D12211
51
Aircraft studies of in-cloud sulfate production
52
Aircraft studies of in-cloud sulfate production
Santarpia, J. L., Collins, D. R., Hegg, D. A., Kaku, K. C., Covert, D. S., Jonsson, H. H., and Buzorius, G., 2011.
“Estimates of aqueous-phase sulfate production from tandem differential mobility analysis,” Atmospheric Environment,
45, pp 5484 – 5492
53
Aircraft studies of in-cloud SOA production
Sorooshian, A., V. Varutbangkul, F. J. Brechtel, B. Ervens, G. Feingold, R. Bahreini, S. M. Murphy, J. S. Holloway, E. L.
Atlas, G. Buzorius, H. Jonsson, R. C. Flagan, and J. H. Seinfeld, 2006. “Oxalic acid in clear and cloudy atmospheres:
Analysis of data from International Consortium for Atmospheric Research on Transport and Transformation 2004,” J.
Geophys. Res. 111, D23S45, doi:10.1029/2005JD006880.
54
Possible role of H2O2 produced in biogenic SOA?
Wang, Y., H. Kim and S. E. Paulson (2011). "Hydrogen peroxide generation from alpha- and
beta-pinene and toluene secondary organic aerosols." Atmospheric Environment 45(18):
3149-3156.
55
FEP Teflon layers and pressure differentials
Po ~ 1000 mbar
P1 << Po P: 20 ~ 400mbar
P2 > P1 P ~ 1 mbar
P3 > P2 P ~ 1mbar
Al
rings
ePTFE membrane
FEP bag deflection
due to P
56
Excessive settling losses in static chamber
57
Chamber rotation
58