Journal of Geophysical Research-Atmospheres
Supporting Information for
Chemical imaging of ambient aerosol particles: observational constraints on
mixing state parameterization
Rachel E. O’Brien,1,2# Bingbing Wang,3 Alexander Laskin,3 Nicole Riemer,4 Matthew
West,5 Qi Zhang,6 Yele Sun,6 Xiao-Ying Yu,7 Peter Alpert,8% Daniel Knopf,8 Mary K.
Gilles,2 Ryan Moffet,1*
[1] Department of Chemistry, University of the Pacific, Stockton, CA 95211, USA
[2] Lawrence Berkeley National Laboratory, Berkeley, California, 94720-8198, USA
# Now at, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology,
Cambridge, MA, 02139, USA
[3] William R. Wiley Environmental and Molecular Sciences Laboratory, Pacific Northwest National
Laboratory, Richland, WA, 99352, USA
[4] Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
[5] Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana,
IL 61801, USA
[6] Department of Environmental Toxicology, University of California Davis, Davis, CA 95616, USA
[7] Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland,
WA, 99354, USA
[8] Institute for Terrestrial and Planetary Atmospheres, School of Marine and Atmospheric Sciences, Stony
Brook University, Stony Brook, New York, 11794-5000, USA
% Now at, Institut de Recherches sur la Catalyse et l’Environnement de Lyon, Centre National de la
Recherche Scientifique, Université Claude Bernard Lyon 1, 69626 Villeurbanne, France
Contents of this file
Text S1
Figure S1
Tables S1-S2
Additional Supporting Information (Files uploaded separately)
Captions for Tables S3 to S8
Introduction
1
Text includes additional information on the calculation of the composition for the mixed
inorganic and the combination of the two techniques. Figure S1 shows bulk mass
fractions for T0 and T1 with the concentration of organic and elemental carbon (soot or
BC) measured during the same hour overlaid on top. Tables S1-S8 provides data
supporting the figures in the main text.
Text S1.
Mixed inorganic composition calculation
The assumption that ammonium sulfate is the inorganic component leads to the
largest uncertainty in the mass calculations. To test the effect of different assumed
inorganic compositions, an analysis was carried out using a mixture of typical inorganic
components: (NH4)2SO4, Na2SO4, NH4NO3, and NaNO3. Aerosol Mass Spectrometry
(AMS) [Setyan et al., 2012] and Particle into Liquid Samplers (PILS) [Zaveri et al., 2012]
were co-located at both field sites and provided quantitative measurement of ions and
anions in aerosols. The AMS has a size cut-off of ~1 m vacuum aerodynamic diameter
and the PILS has a pre-impactor with a d50 of 1 m [Sorooshian et al., 2006].
AMS and PILS data at T0 and T1 were used to estimate the mole ratios of the
ions (SO42- : NO3- and NH4+: Na+). The measurements with the AMS at T0 stopped a
few days before the samples discussed here so the AMS concentrations for T0 are
taken from the average values a few days prior (6/22/2010-6/25/2010) [Zaveri et al.,
2012]. From AMS measurements during the same time stamps (T1) or a few days prior
(T0), the ratio of SO42- to NO3- averaged 2-5. The charge balance of NH4+ to SO42- and
NO3- was nearly even at T1 over the 27th and 28th ( 1.1 on average) consistent with AMS
results that the particles were fully neutralized at T1 [Setyan et al., 2012]. At T0 for the
22nd- 25th, the charge balance was slightly lower (0.93 on average).
To compare Na+ to NH4+, PILS data was used and the NH4+ concentration was
estimated by taking the SO42- and NO3- concentrations from the PILS data and
calculating the concentration of NH4+ needed to balance the charges. Using this
estimate, there was approximately 1-3 times as much NH4+ as Na+ from the PILS data at
T0 and T1. The ratios for NH4+ to Na+ of 3:1 and for SO42- to NO3- of 2:1 provided the
largest difference in the mass absorption coefficient compared to (NH4)2SO4 as the
inorganic component. Thus, these ratios were used giving estimated ratios for the mixed
inorganics of 6:2:3:1 for (NH4)2SO4:Na2SO4:NH4NO3:NaNO3. These ratios lead to
weighted absorption coefficients of in*,320 = 9,470 cm2/g and in*,278 = 12,300 cm2/g
[Henke et al., 1993] and a density of 1.95 g/cm3. These values were used for new mass
and mixing state parameter calculations. The difference between the values determined
using the mixed inorganic and ammonium sulfate are shown as error bars on Figure 2 in
the main text.
STXM/NEXAFS and CCSEM/EDX and future work
The analysis presented in this manuscript was carried out on data sets collected
for previous publications [Knopf et al., 2014, Moffet et al., 2013]. For those projects, the
data from STXM/NEXAFS and CCSEM/EDX were collected on samples from the same
two days but were not collected on the same samples. Thus, the analysis presented in
this manuscript provides insights into the information that can be gained from each of the
techniques separately.
Future work in this area, however, would greatly benefit from the application of
both techniques to the same samples and, in the best case, to the same particles. The
application of both techniques to the same samples would provide C, N, and O
2
quantification from STXM/NEXAFS and quantification of the other elements from
CCSEM/EDX. This data would reduce the uncertainty in the identity of the inorganic
used for the STXM calculations. The application of both techniques to the same particles
would be a more time intensive process but would enable a per-particle mass based
mixing state analysis for the full elemental composition. Additionally, the elemental
composition could be apportioned to expected inorganic components. This analysis
could provide the ability to estimate the O/C of the organic component which could
provide additional information on aerosol sources and aging.
References
Henke, B. L., E. M. Gullikson and J. C. Davis (1993), X-Ray Interactions Photoabsorption, scattering, transmission and reflection at E=50-30,000 eV, Z=1-92
(VOL 54, PG 181, 1993). Atom. Data Nucl. Data Tables 55(2): 349-349.
Knopf, D. A., P. A. Alpert, B. Wang, et al. (2014), Microscpectriscopic imaging and
characterization of individually identified ice nucleating particles from a case field
study. J. Geophys. Res.-Atmos. 119 (17), doi: 10.1002/2014JD021866.
Moffet, R. C., T. C. Roedel, S. T. Kelly, et al. (2013), Spectro-microscopic
measurements of carbonaceous aerosol aging in Central California. Atmos. Chem.
Phys. 13(20): 10445-10459.
Setyan, A., C. Song, M. Merkel, et al. (2014), Chemistry of new particle growth in mixed
urban and biogenic emissions - insights from CARES. Atmos. Chem. Phys. 14(13):
6477-6494.
Sorooshian, A., F. J. Brechtel, Y. L. Ma, et al. (2006), Modeling and characterization of a
particle-into-liquid sampler (PILS). Aerosol Sci. Technol. 40(6): 396-409.
Zaveri, R. A., W. J. Shaw, D. J. Cziczo, et al. (2012), Overview of the 2010
Carbonaceous Aerosols and Radiative Effects Study (CARES). Atmos. Chem. Phys.
12(16): 7647-7687.
3
Figure S1. Bulk mass fractions for T0 (a, b) and T1 (c, d) for organic carbon (OC,
green), inorganic (IN, blue),and black carbon (BC, red). The concentration of OC and
BC (also called elemental carbon or EC) measured during the same hour with a
collocated Sunset ECOC are shown with white markers on the right axis. For the
sample collected at T1 6/28/2010 at 11:37 am there was no corresponding ECOC
measurement.
4
size range
(um)
0.001-0.09
0.1-0.19
0.2-0.29
0.3-0.39
0.4-0.49
0.5-0.59
0.6-0.69
0.7-0.79
0.8-0.89
0.9-0.99
1.0-1.09
1.1-1.19
1.2-1.29
1.3-1.39
1.4-1.49
1.5-1.59
1.6-1.69
1.7-1.79
1.8-1.89
1.9-1.99
2.0-2.09
2.1-2.19
2.2-2.29
2.3-2.39
number of
particles
24
944
1357
1263
1214
927
766
560
386
307
232
182
115
97
70
60
47
34
27
29
26
19
21
16
Average
organic
mass (fg)
0.11 ± 0.035
0.46 ± 0.26
1.3 ± 0.62
2.8 ± 1.3
5.5 ± 2.6
9.6 ± 5.1
15 ± 6.6
20 ± 9.8
30 ± 15
38 ± 19
47 ± 21
61 ± 32
72 ± 31
88 ± 44
130 ± 72
140 ± 83
160 ± 87
140 ± 50
160 ± 32
230 ± 105
220 ± 104
250 ± 67
240 ± 62
380 ± 178
Average
inorganic
mass (fg)
0.40 ± 0.070
0.73 ± 0.55
2.2 ± 1.6
4.6 ± 3.3
8.2 ± 5.2
14 ± 8.8
21 ± 13
29 ± 18
44 ± 31
59 ± 36
83 ± 49
100 ± 53
140 ± 83
180 ± 110
230 ± 120
240 ± 120
330 ± 190
360 ± 160
420 ± 150
570 ± 260
650 ± 300
730 ± 230
730 ± 370
1100 ± 400
Average
black
carbon
mass (fg)
0.00 ± 0.004
0.030 ± 0.15
0.13 ± 0.51
0.31 ± 1.1
0.47 ± 1.8
0.95 ± 3.4
1.3 ± 4.6
1.8 ± 6.7
2.2 ± 8.4
3.9 ± 15
3.8 ± 16
5.9 ± 24
1.8 ± 4.5
4.7 ± 21
3.5 ± 12
4.1 ± 18
0.72 ± 2.0
24 ± 100
22 ± 76
0.87 ± 3.1
13 ± 31
8.2 ± 24
2.6 ± 7.4
12 ± 37
Average
particlespecific
diversity, Di
1.7 ± 0.12
1.9 ± 0.24
1.9 ± 0.27
1.9 ± 0.29
1.9 ± 0.27
1.9 ± 0.26
2.0 ± 0.27
1.9 ± 0.24
1.9 ± 0.24
1.9 ± 0.25
1.9 ± 0.24
1.9 ± 0.24
1.9 ± 0.19
1.9 ± 0.19
1.9 ± 0.18
1.9 ± 0.20
1.8 ± 0.15
1.9 ± 0.23
1.8 ± 0.21
1.8 ± 0.13
1.8 ± 0.20
1.8 ± 0.21
1.8 ± 0.14
1.7 ± 0.11
Table S1. Size separated data for T0, STXM/NEXAFS analysis. The average masses
of organic, inorganic, and black carbon are given in femtograms. The standard deviation
is given for each size bin. Size bins with less than 10 particles were not included in the
figure.
5
size range
(um)
0.001-0.09
0.1-0.19
0.2-0.29
0.3-0.39
0.4-0.49
0.5-0.59
0.6-0.69
0.7-0.79
0.8-0.89
0.9-0.99
1.0-1.09
1.1-1.19
1.2-1.29
1.3-1.39
1.4-1.49
1.5-1.59
1.6-1.69
1.7-1.79
1.8-1.89
Average
number of organic
particles
mass (fg)
0.12 ±
9 0.040
632
1002
1123
986
846
671
560
408
301
212
160
118
66
44
30
27
15
11
0.48 ± 0.27
1.3 ± 0.67
3.0 ± 1.4
5.5 ± 2.7
9.5 ± 4.5
15 ± 7.3
23 ± 11
33 ± 17
45 ± 22
56 ± 28
74 ± 34
93 ± 49
130 ± 57
140 ± 65
180 ± 75
220 ± 120
230 ± 130
230 ± 110
Average
inorganic
mass (fg)
Average
black carbon
mass (fg)
0.28 ± 0.17
0.00 ± 0.00
0.012 ±
0.092
0.079 ± 0.33
0.21 ± 0.85
0.34 ± 1.3
0.50 ± 1.9
0.69 ± 2.8
0.99 ± 3.6
1.3 ± 5.7
2.0 ± 8.1
2.9 ± 13
3.6 ± 11
3.2 ± 11
1.3 ± 3.0
1.9 ± 4.8
0.72 ± 1.9
4.9 ± 15
3.9 ± 7.3
1.7 ± 3.0
0.39 ± 0.31
1.0 ± 0.71
2.2 ± 1.4
4.4 ± 2.8
7.3 ± 4.1
11 ± 6.0
17 ± 11
24 ± 13
31 ± 15
43 ± 29
53 ± 33
69 ± 48
93 ± 71
85 ± 38
110 ± 54
140 ± 74
150 ± 69
190 ± 100
Average
particlespecific
diversity, Di
1.7 ± 0.17
1.8 ± 0.20
1.9 ± 0.26
1.9 ± 0.25
1.9 ± 0.26
2.0 ± 0.26
2.0 ± 0.24
2.0 ± 0.25
2.0 ± 0.21
2.0 ± 0.24
2.0 ± 0.21
2.0 ± 0.26
2.0 ± 0.25
1.9 ± 0.13
2.0 ± 0.18
1.9 ± 0.09
2.0 ± 0.24
1.9 ± 0.19
1.9 ± 0.20
Table S2. Size separated data for T1, STXM/NEXAFS analysis. The the average
masses of organic, inorganic, and black carbon are given in femtograms. The standard
deviation is given for each size bin. Size bins with less than 10 particles were not
included in the figure.
6
Table S3. Size separated data for T0, CCESM/EDX analysis. The average mass of the
elements (in femtograms) are given with ± the standard deviation.
Table S4. Size separated data for T1, CCSEM/EDX analysis. The average mass of the
elements (in femtograms) are given with ± the standard deviation.
Table S5. STXM/NEXAFS data from Cares T0 6/27/2010 and 6/28/2010. The sample
day and time are given. Total mass (in femtograms) of organic (OC), inorganic (IN) and
black carbon/soot (BC) per particle. Labels correspond to: 1 = OC, 2 = INBCOC, 3 =
BCOC, 4 = INOC; the size of the particle is give as the area equivalent diameter (AED)
in microns
Table S6. STXM/NEXAFS data from Cares T1 6/27/2010 and 6/28/2010. The sample
day and time are given. Total mass (in femtograms) of organic (OC), inorganic (IN) and
black carbon/soot (BC) per particle. Labels correspond to: 1 = OC, 2 = INBCOC, 3 =
BCOC, 4 = INOC; the size of the particle is give as the area equivalent diameter (AED)
in microns
Table S7. CCSEM/EDX data from Cares T0 6/27/2010 and 6/28/2010. The sample day
and time are given. Total mass (in femtograms) of each element for each particle are
given. Labels correspond to: 1 = sea salt, 2 = sea salt/sulfate, 3 = CNOS
(carbonaceous/sulfate), 4 = CNO (carbonaceous), 5 = other; the size of the particle is
give as the average diameter in microns
Table S8. CCSEM/EDX data from Cares T1 6/27/2010 and 6/28/2010. The sample day
and time are given. Total mass (in femtograms) of each element for each particle are
given. Labels correspond to: 1 = sea salt, 2 = sea salt/sulfate, 3 = CNOS
(carbonaceous/sulfate), 4 = CNO (carbonaceous), 5 = other; the size of the particle is
give as the average diameter in microns
7