fog processing of atmospheric organic compounds during the ... · san joaquin valleywide air...
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Funding fromSan Joaquin Valleywide Air Pollution Study Agency
National Science Foundation (NSF)
Funding fromSan Joaquin Valleywide Air Pollution Study Agency
National Science Foundation (NSF)
Fog Processing of atmospheric organic compounds duringthe California Regional PM10/PM2.5 Air Quality Study
(CRPAQS)
P. Herckes, T. Lee, L. Trenary, G. Kang, and J.L. Collett, Jr.Colorado State University
Main site: Angiola
Satellite sites:Helm
Bakersfield
McKittrick
Fog study sites
Instrumentation
CASCC, sf-CASCC, ss-CASCC, ss-sf-CASCC, 5-stage fog collector,CHRCC, Tower (4 levels of Al-CASCC2), Deposition PlatesPVM, CSASP, CSU-OFDMOUDI, organic Aerosol, Continuous Peroxide Analyzer
December 10th 2000 - February 2nd 2001December 10th 2000 - February 2nd 2001
ss-CASCC: Bulk fogwaterPM 2.5 + interstitial aerosol
ss-sf-CASCC: size fractionated fogSize-cut: approx 17 µm
fog/ground based cloud sampling
Investigation of bulk properties of OMIndividual compound speciation
Variation with drop-sizeProcessing of carbonaceous particles
Investigation of bulk properties of OMIndividual compound speciation
Variation with drop-sizeProcessing of carbonaceous particles
Total and Dissolved Organic Matter Characterization
sample TOC
DOC 1
DOC 2
DOC 3
DOC aliquot
MW < 1000, DOC aliquot
MW < 500, DOC aliquot
Filtration 1
Ultrafiltration 1, YM1
Ultrafiltration 2, YM05
Total Organic Carbon concentrations
TOC mgC/L
avg (min-max)
CRPAQS
Angiola 10 (2-41) Herckes et al., 2002 Helm 6-16 Herckes et al., 2002 Bakersfield 27 Herckes et al., 2002 IMS 95 5-41 Collett et al., 1999 Bakersfield 9-276 Jacob et al., 1984 Davis 32.5 (5-111) Zhang et al, 2001 Po Valley fogs (Italy) 15-108 Gelencser et al., 2000
Total and Dissolved Organic Matter Characterization
sample TOC
DOC 1
DOC 2
DOC 3
DOC aliquot
MW < 1000, DOC aliquot
MW < 500, DOC aliquot
Filtration 1
Ultrafiltration 1, YM1
Ultrafiltration 2, YM05
0
2
4
6
8
10
12
14
16
18
20
0 2 4 6 8 10 12 14 16 18 20TOC (ppmC)
DO
C (p
pmC
)
ss-CASCCss-sf-CASCC Largess-sf-CASCC Small1:1 line
Total vs Dissolved Organic Carbonfog-Angiola (SJV, Ca)
Total vs Dissolved Organic Carbonfog-Angiola (SJV, Ca)
25% insoluble (0-64%)25% insoluble (0-64%)
Total and Dissolved Organic Matter Characterization
sample TOC
DOC 1
DOC 2
DOC 3
DOC aliquot
MW < 1000, DOC aliquot
MW < 500, DOC aliquot
Filtration 1
Ultrafiltration 1, YM1
Ultrafiltration 2, YM05
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
12/17 1/10 1/15 1/17 1/21 1/31
MW < 500
500 < MW < 1000
MW > 1000
Dissolved Organic Matter
significant fraction of DOC has high Molecular Weight (MW)significant fraction of DOC has high Molecular Weight (MW)
Investigation of bulk properties of OMIndividual compound speciation
Variation with drop-sizeProcessing of carbonaceous particles
Investigation of bulk properties of OMIndividual compound speciation
Variation with drop-sizeProcessing of carbonaceous particles
samplefiltration
Soluble: liquid sample Insoluble: filter
3 x 25 ml DCMUltrasonic bath
extractSPME
LLE: 3 x 25ml DCM
(SPE) extraction
GC-MS analysis
neutralmethylated
silylated derivatization+ analysis
pH, formaldehyde, TOC/DOC,….
Molecular composition of organic matter in California fog
A large number of different compounds has been identified in the fogwater
Polar compounds:
carboxylic acids (C1-C36)di-carboxylic acids (C2-C9)aromatic acids (benzoic acid…)resin acids (pimaric acid,…)aldehydes (formaldehyde,..)phenols (phenol, nitro-phenol….)methoxyphenols (vanillin, ethyl-guaiacol,…)oxygenated PAH (9, 10 Anthracenedione,..)pesticides (Diazinon, Penoxaline,..)
Nonpolar compounds:
n-alkanes (C20* – C39)Polyaromatic Hydrocarbons (PAH) (pyrene,…)…
Polar compounds:
carboxylic acids (C1-C36)di-carboxylic acids (C2-C9)aromatic acids (benzoic acid…)resin acids (pimaric acid,…)aldehydes (formaldehyde,..)phenols (phenol, nitro-phenol….)methoxyphenols (vanillin, ethyl-guaiacol,…)oxygenated PAH (9, 10 Anthracenedione,..)pesticides (Diazinon, Penoxaline,..)
Nonpolar compounds:
n-alkanes (C20* – C39)Polyaromatic Hydrocarbons (PAH) (pyrene,…)…
OOH
benzoic acidCO2H
pimaric acid
vanillin
OOOH
syringol OOH
O
pyrene
O
O
9,10 anthracenedione
0
5
10
15
20
25
C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C26
ng/m
L
insolublessolubles
n-alkanoic acids (Angiola (CA), December 17, 2000)
Smaller MW compounds predominantly solubleLarger MW compounds predominantly insolubleSmaller MW compounds predominantly solubleLarger MW compounds predominantly insoluble
Investigation of bulk properties of OMIndividual compound speciation
Variation with drop-sizeProcessing of carbonaceous particles
Investigation of bulk properties of OMIndividual compound speciation
Variation with drop-sizeProcessing of carbonaceous particles
TOC variation with droplet size
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
TOC of large droplets (ppmC)
TOC
of s
mal
l dro
plet
s (p
pmC
Higher concentrations in smaller dropletsRatio 2.8 on average (0.8-6.3)Higher concentrations in smaller dropletsRatio 2.8 on average (0.8-6.3)
Individual organic compounds
0
5
10
15
20
25
30
0 5 10 15 20 25 30large droplet concentration (d>17µm) in µeq/L
smal
l dro
plet
con
cent
ratio
n (d
<17µ
m) i
n µe
q/L
1:1 lineoxalic acid
Consistent with inorganic compounds
Dissolved Organic Carbon75%
insoluble organic material
25%MW >1000 Da
20%
500 Da < MW <1000 Da19%
MW < 500 Da61%
0.75% (0.55-0.95%)n-alkanoic acids
(C9-C28)
<0.1% (0.05-0.1%)n-alkanes (C10-C40)
0.1% (0.02-0.25%)30 PAH and oxy-PAH
8%(2-24%) formaldehyde
59% unknow ns
30% (1-64%)mono acids C1-C3
2% (0-4%)di-acids (C2-C6)
What we learned about the organic matter
1.6% (<0.1% - 2.6%)
5.1 %(1.1-11%)6.6% (0.2-10%)
11.3% (0.3-27%)
0
2
4
6
8
10
12
acetic acid formic acid formaldehyde oxalic acid
% D
OC
Dominant individual organic species
Investigation of bulk properties of OMIndividual compound speciation
Variation with drop-sizeProcessing of carbonaceous particles
Investigation of bulk properties of OMIndividual compound speciation
Variation with drop-sizeProcessing of carbonaceous particles
Limited information due to low time resolutionLimited information due to low time resolution
Scavenging of organic carbon
0
2
4
6
8
10
12
1/14/2001 1/15/2001 1/16/2001 1/17/2001 1/18/2001 1/19/2001 1/20/2001
ratio
OC
/EC
and
TC
in u
g/m
3
0
100
200
300
400
500
600
700
800
LWC
in m
g/m
3
OC/ECTCLWC
13 hour fog event:294 g/m2 water (1 inch =25.4kg/m2)1.2 mg of C/m2
Considering a fog layer of 100m depthdecrease of 12 µgC/m3
significant removal of ambient OC (~10µgC/m3)
- some from volatile species!- entrainment from upper layers
Fog deposition flux: case example December 17/18th, 2000
Conclusions
- organic matter (OM) is an important component of SJV fogs
- 25% of OM is associated with insoluble material
- large fraction of OM has high molecular weight
- only a small fraction is identified at molecular level
- monocarboxylic acids are the dominant species
- small droplets are enriched in OM
- deposition fluxes suggest a significant removal of OM by fogs
Related posters
“Overview of fog studies during the California RegionalPM10/PM2.5 Air Quality Study (CRPAQS)”
7PB10“Aerosol Processing and removal by fogs: Observations in radiation fogs during the CRPAQS study “
7PB11
Acknowledgements
E. Sherman, S. Emert, J. Reilly for assistance during theplanning and execution of the field study