IMPROVE Ion Studyand
Other IMPROVE Special Studies
Jeffrey L. Collett, Jr.Colorado State University(with contributions fromcollaborators at CSU, NPS, and UCDavis)
Funding: NPS/IMPROVE Western Resource Advocates
Outline
The IMPROVE Ion/Nitrate Study– Motivation– Questions and approach– Findings and implications
Other IMPROVE special studies– Yosemite smoke study– IMPROVE denuder tests– Coarse particle speciation– Mobile air quality lab
Ion StudyMotivation
Nitrate is animportantcontributor toPM at manylocationsNitrate maybe present infine orcoarsemodesSamplingmethodologyissues
HNO3(g) + NH3(g) NH4NO3(p)
HNO3(g) + NaCl(p) NaNO3(p) + HCl(g)
2 HNO3(g) + CaCO3(p) Ca(NO3)2(p) + CO2 + H2O
Nitrate inBig Bend
High PM2.5nitrateassociatedwith flowfrom Gulf
Nitratereplacedchloride insea saltaerosol
y = 1.14xR2 = 0.72
y = 0.33xR2 = 0.69
0
20
40
60
80
100
120
140
160
180
200
0 20 40 60 80 100 120 140 160 180 200
Na+(neq/m3)
([Cl- ]+
[NO
3- ] ) o
r [C
l- ] (ne
q/m
3 )([C-]l+[NO3-]) vs [Na+]Sea water ratio(Cl-/Na+)[Cl-] vs [Na+]Linear (([C-]l+[NO3-]) vs [Na+])Linear ([Cl-] vs [Na+])
slope for sea water1.164 ([Cl-]/[Na+])
NaCl NaNO3
HNO3 HCl
Nitrate in Big Bend
Nitrate foundin coarsemodeparticles
– Mode size~4-5 µm
– Sizedistributionsimilar to Na+
PM2.5 includestail of coarsemode
0
50
100
150
200
250
300
350
0.1 1 10 100
dC/d
log(
Dp)
(neq
/m3) sulfate
0
50
100
150
200
250
0.1 1 10 100
Aerodynam ic Diam eter (µm )
dC/d
log(
Dp)
(neq
/m3)
ammonium
0
5
10
15
20
25
0.1 1 10 100
nitrate
0
5
10
15
20
25
30
0.1 1 10 100
Aerodynam ic Diam eter (µm )
sodium
0
5
10
15
20
0 5 10 15 20Na+ (neq/m3)
Cl-
or (
(NO
3-)+
(Cl-)
)(n
eq/m
3)
Na+ vs. Cl-
Na+ vs.((NO3-)+(Cl-))
Slope for sea water (1.164)
NH4NO3
Yosemiteresults
Carbon-dominated aerosol(NH4)2SO4 dominant saltNO3
- replaced Cl- in sea salt
0
5
10
15
20
25
30
8/12 8 /13 8 /14 8 /15 8 /16 8 /17 8 /18 8 /19 8 /20 8 /21 8 /22 8 /23 8 /24 8 /25 8 /26 8 /27
neq/
m3
C l- NO 3- Na+
2-week excerpt, PILS 15-min data
IMPROVE ion special study goals
Determine characteristics of ionic aerosol present atselected IMPROVE sites
– Ionic composition– Ion size distributions– Gas-particle distribution of NH3(g)/NH4
+(p) and HNO3(g)/NO3-(p)
Evaluate IMPROVE ion sampling and analysisapproach
– Combination of field and lab studies– Filter choice, filter extraction method, and denuder protocol
Ion study locations
San Gorgonio
Bondville
Big Bend
Yosemite
Grand Canyon
Brigantine
Sequoia
Study equipment
• 24 hr URG PM2.5 cyclone/annular denuder/ filter pack sampler
• MOUDI impactor (10-stage)
• 15 min PM2.5 PILS/IC system• Particle into Liquid Sampler• Ion Chromatograph
36
31
26
21
16
11
6
1
Conc
entra
tion,
ug/
m3
2/2/
2003
2/3/
2003
2/4/
2003
2/5/
2003
2/6/
2003
2/7/
2003
2/8/
2003
2/9/
2003
2/10
/200
3
2/11
/200
3
2/12
/200
3
2/13
/200
3
2/14
/200
3
2/15
/200
3
2/16
/200
3
2/17
/200
3
2/18
/200
3
2/19
/200
3
2/20
/200
3
2/21
/200
3
2/22
/200
3
2/23
/200
3
Date
NH4+_ug/m3 NO3-_ug/m3 SO4=_ug/m3
Bondville 2/03
NO3- and SO4
2- both importantNH4NO3 in submicron mode
0
10
20
30
40
50
< 0.
18
0.18
-0.3
2
0.32
-0.5
6
0.56
-1.0
1.0-
1.8
1.8-
3.2
3.2-
5.6
5.6-
10.0
10.0
-18.
0
>18.
0
NO3-, neq/m3SO4=, neq/m3Na+, neq/m3NH4+, neq/m3
Aver
age
Con
cent
ratio
n, n
eq/m
3
Aerodynamic Diameter, µm
San Gorgonio4/03
Large diurnal variabilitySubmicron NH4NO3 dominant
0
5
10
15
20
25
< 0.
18
0.18
-0.3
2
0.32
-0.5
6
0.56
-1.0
1.0-
1.8
1.8-
3.2
3.2-
5.6
5.6-
10.0
10.0
-18.
0
>18.
0
NO3-, neq/m3SO4=, neq/m3Na+, neq/m3NH4+, neq/m3
Aver
age
Con
cent
ratio
n, n
eq/m
3
Aerodynamic Diameter, µM
700
600
500
400
300
200
100
0
Con
cent
ratio
n, n
eq/m
3
NH4+ , neq/m3 NO 3-, neq/m 3 SO 4=, neq/m3
4/4
4/5
4/6
4/7
4/8
4/9
4/10
4/11
4/12
4/13
4/13
4/14
4/15
4/16
4/17
4/18
4/19
4/20
4/21
4/22
4/23
4/24
4/25
4/26
4/27
30
20
10
0
Con
cent
ratio
n, u
g/m
3
NO3-, ug/m3 SO4=, ug/m3 NH4+, ug/m3 K+, ug/m3
7/2
7/3
7/4
7/5
7/6
7/7
7/8
7/9
7/10
7/11
7/12
7/13
7/14
7/15
7/16
7/17
7/19
7/18
7/20
7/21
7/22
7/23
7/24
7/25
7/26
7/27
7/28
7/29
San Gorgonio 7/03
More regular diurnal variabilitySome days sulfate-dominated
K+ spikes
Grand Canyon
0
2
4
6
8
10
12
0 2 4 6 8 10
Na+ (neq/m3)
Con
cent
ratio
n (n
eq/m
3)
Cl-NO3- + Cl-sea salt
Grand Canyon MOUDI average
0
2
4
6
8
10
12
< 0.18 0.18 - 0.32 0.32 - 0.56 0.56 - 1.0 1.0 - 1.8 1.8 - 3.2 3.2 - 5.6 5.6 - 10.0 10.0 - 18.0 >18.0
aerodynamic diameter (µm)
neq/
m3
SO4=NH4+NO3-Na+Ca2+
GrandCanyon
Nitrate in coarse modeAppears to beassociated with Na+
and Ca2+
Sampling and extraction issues
Does water efficiently extractnitrate from nylon filters?
– HNO3 not efficientlyrecovered with waterextraction
– Typically useNaHCO3/Na2CO3
What happens to NH4NO3volatilized from nylon filters?
– HNO3 trapped? Decrease inwater extraction efficiency?
– NH3 lost? Bias in measuredPM2.5 ammonium?
NH4NO3
NH3(g)
NH3(g) + HNO3 (g) NH4NO3(p)
NO3- & NH4
+
on nylon
Nylon filterextraction by watershowed no bias infirst three studies
Significant NH4+
lost from nylonfilter
– Nylon recapturesvolatilized NO3
-
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10 12 14 16
Nylon D.I. H2O, ug/m3, BondvilleNO3-, D.I. H2O, ug/m3, SG AprilNO3- D.I. H2O, ug/m3, Grand Canyon1:1 Line
Nyl
on b
y D
.I. H
2O e
xtra
ctio
n, u
g/m
3
Nylon by IC extraction, µg/m3
0
10
20
30
40
50
60
70
0 5 10 15 20 25 30
BNH4+%, BondvilleBNH4+%, SG AprilBNH4+%, GC
NH
4+ loss
from
Nyl
on fi
lter,
%
Day of Month
0
20
40
60
80
100
Jul/1 Jul/6 Jul/11 Jul/16 Jul/21 Jul/26 Jul/31
BNH4+%BNO3-%
Date
San GorgonioJuly (latest results)
~ 25% of nitrate not extractedfrom nylon filter with water
NH4+ loss ~ 20-50%
0
1
2
3
4
5
0 1 2 3 4 5
NO3-, D.I. 1:1
NO3-(IC), µg/m3
y = m2 * M0ErrorValue
0.0212750.75792m2 NA1.6439Chisq
NA0.92249R2
Yosemitespecial study
July-September2002Focus onsmokeAerosoldominatedby OC
POM73%
Black C2%
Soil6% NH4+
4%
Na+1%
K+0%
Ca2+0%
NO2-0%
Cl-0%
Mg2+0%
NO3-3%
Oxalate1%
Ions19%
SO42-10%
POMBlack CSoilCl-NO2-NO3-SO42-OxalateNa+NH4+K+Mg2+Ca2+
Study average PM2.5 composition
Yosemitespecial study
Large changes in OC– EC remained small
“Contemporary” carbondominant
– Wood smoke– Biogenic production
Molecular markers indicatepresence of wood smokeand secondary biogenicparticles
– Vehicle contribution appearssmall
0
2
4
6
8
10
12
14
7/10 7/15 7/20 7/25 7/30 8/4 8/9 8/14 8/19 8/24 8/29 9/3
Car
bon
( µg
m-3
)
Yosemite size distributions
Size distributionsmeasured withDifferential MobilityAnalyzer (DMA)Two submicron modespresent during smokeperiod
SMOKE
16 Aug 2002 (DOY 228) 22:30 PST08 Aug 2002 (DOY 220) 03:45 PST
“CLEAN”
Yosemite size distributions - II
Aerosol Mass Scattering Efficiency– increases during smoky periods
K+
(µg/
m3 )
Mas
s sca
tterin
g ef
ficie
ncy
(m2 /g
)
Yosemite aerosol hygroscopicity
Hygroscopicity of100 and 200 nmparticles measuredwith HygroscopicTandem DifferentialMobility Analyzer(HTDMA)
Smoke-dominatedaerosol much lesshygroscopic than“normal” Yosemitesummer aerosol
0 2 4 6 8 10 12 14
1.05
1.10
1.15
1.20
1.25
1.30
1.35
1.40
Equation: y = A1*exp(-x/t1) + y0
Chi 2/DoF = 0.001R 2 = 0.723 y0 1.102 ±0.007A1 0.434 ±0.067t1 1.386 ±0.201
GF
(RH
=80%
)
Carbon/Ionic Mass Ratio
IMPROVE denuder tests (UC Davis)
Differentdenuderconfigurationstested
– Noperformancedifferencesobserved
– Lab testsplanned atCSU
HANC
0100200300400500600700800900
5/1/
03
5/3/
03
5/5/
03
5/7/
03
5/9/
03
5/11
/03
5/13
/03
5/15
/03
5/17
/03
5/19
/03
5/21
/03
5/23
/03
5/25
/03
5/27
/03
5/29
/03
5/31
/03
ng/m
3HNO3(g)
None
New
Bare Al
No glyc
Used
Coarse particle speciation (UC Davis)
PM10 speciation9 sites
– Bondville– Great Smokies– Grand Canyon– San Gorgonio– Sequoia– Brigantine– Upper Buffalo– Bridger– Mount Rainier
Operational by 1/1/04– Several sites already
operating– Overlap with ion study
Will run for 1 year
New IMPROVE mobileair quality lab
Mobile platform– Special study deployment– Some on-road
measurement capabilities
Measurement capabilities– Particle and trace gas
composition– Aerosol size distributions– Particle hygroscopicity– Trace gases
Summary
Nitrate present in– Submicron ammonium nitrate particles
Bondville, ILSan Gorgonio, CA
– Coarse mode sodium or calcium nitrate particlesBig Bend NP, TX Yosemite NP, CAGrand Canyon NP, AZ
Nylon filter– DI water extraction may not always fully recover NO3
-
– Yields negatively biased NH4+ concentrations
Yosemite aerosol dominated by modern carbon– Particles slightly hygroscopic
HNO3 denuder tests show little dependence on coatingCoarse particle speciation study beginningMobile lab being constructed for future special studies
IMPROVE ion study fieldcampaigns
6 one-month campaignsBondville (midwest) - February2003San Gorgonio (southern CA) –April and July 2003Grand Canyon – May 2003 (co-sponsored by LAWFR)
– Brigantine (NE coastal) –November 2003
– Sequoia (Sierra Nevada) –February 2004
Measurements– MOUDI sampler – ion size
distributions– 3 Parallel URG denuder/filter-
pack samplers running differentprotocols
– PILS sampler – 15 minute PM2.5anions and cations
Mobile laboratory
Nitrate replacement
NH4NO3 formation not favoredthermodynamically in acidicaerosol
– NH3(g) will first neutralize sulfateH2SO4 NH4HSO4 (NH4)2SO4
Once aerosol is neutralized,NH4NO3 formation may occur
– f(T,RH)If SO4
2- is decreased, NO3- may
replace it– Two NO3
- replace each SO42-
– Sulfate reduction could producePM mass increase
SO42-
98 g/mole
NO3-
62 g/moleNO3
-
62 g/mole
HN
O3 denuder
NH
3 denuder PM
2.5 N
H3 denuder
HN
O3 denuder
NH
3 denuder
N filter (IC)
PM2.5
HN
O3 denuder
NH
3 denuder
Filter A
PM2.5
NH
3 denuder
N filter (H2O)
HN
O3 denuder
HN
O3 denuder
•Modules 1 and 2
•Daily, 24 hr samples
•Compare nylon filterextraction (H2O vs.carbonate/bicarbonate)
•Examine loss of HNO3 andNH3 from nylon filter
•Provide gas-particle phasedistribution for N(-III) andN(V)
•Module 3
•Day/night sampling
•Replicates for precision
•Aerosol acidity/NH4NO3volatilization
•Undenuded sampling onTeflon filter
Initial findings
Nylon filter extraction by water?– EPA study of fall filters collected at numerous STN
and IMPROVE sites gave average 90% extractionefficiency
– CSU Fort Collins samples (Spring 2002) yielded noevidence of lower water extraction efficiency
Fate of volatilized NH4NO3?– EPA study indicated significant ammonia loss
IMPROVE sampling approach
4 modulesModule B for PM2.5 ions– Carbonate-coated denuder removes acidic gases– Nylon filter
Extracted with carbonate/bicarbonate solution (anion ICeluent) for anion analysisExtracted with water for anion + cation analysis
– Sodium interference from IC eluentAnalyzed by IC