atmospheric aerosol from the source to the receptor insights from the pittsburgh supersite spyros...
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Atmospheric Aerosol Atmospheric Aerosol From the Source to the From the Source to the Receptor Receptor Insights from the Insights from the
Pittsburgh SupersitePittsburgh Supersite
Spyros Pandis, Allen Robinson, and Cliff Davidson
Department of Engineering and Public Policy
Carnegie Mellon University
Aerosol Size Distribution
0
10
20
30
40 N
umbe
r (
dN/d
logD
p), c
m-3
x103
0.01 0.1 1 10D iam eter (m icrom eters)
0
10
20
30
40
Vol
ume
(dV
/dlo
gDp),
m
3 /cm
3
Nucleation M ode
Aitken M ode
Condensation Submode
DropletSubmode
Coarse M ode
U ltrafine Particles
F ine Particles Coarse Particles
Accum ulation M ode
Air Pollution in Pittsburgh
USX Tower
July 2, 2001
July 18, 2001
PM2.5=4 g m-3
PM2.5=45 g m-3
FRM PM2.5 Concentrations During PAQS
PM
2.5
(µg
/m3 )
Study Average: 17 µg/m3
0
4
8
12
16
20
24
28
32
36
40
44
48
52
56
60
64
29-Jun 18-Aug 7-Oct 26-Nov 15-Jan 6-Mar 25-Apr 14-Jun
2001 2002
Fine PM CompositionP
M2
.5 (
g/m
3)
0
5
10
15
20
25
30
35
Organic matter Elemental carbon Sulfate Nitrate Ammonium Crustal components
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
2001 2002
PM2.5 mass
0
10
20
30
40
50
60
70
7/1/01
7/8/
01
7/15
/01
7/22
/01
7/29
/01
8/5/
01
8/12
/01
8/19
/01
8/26
/01
PM2.5 Mass Balance (July and August 2001)
PM
2.5 (
µg/m
3)
Organics
Sulfate
Nitrate
AmmoniumAmmonium
EC
Crustal
1 8 15 22 29 5 12 19 26 July August
Mass Balance Closure – July 2001
0
10
20
30
40
50
60
WaterCrustal
NO3
SO4
NH4
EC
OC*1.8
FRM
PM
2.5
(g
m-3)
1 4 7 10 13 16 19 22 25 28 31
Date (July 2001)
Good mass balance was achieved for the winter months
Satellite Sites Outside Pittsburgh
Greensburg
Holbrook
Steubenville
Athens
Florence
Sulfate Mass at Main Site and Satellite Sites
July 26, 2002 (16.2 g m-3)
Increase as winds shift direction
Decrease after a front passed, wind speeds decreased, and some rain fell
Continuous Sulfate Measurements and Long
Range Transport
24:000:00 6:00 12:00 18:000
20
40
60
80 P
M2.
5 sul
fate
(g/
m3)
PM
2.5
Sul
fate
(g
/m3 )
Hour (EST)
0:00 EST 12:00 EST
PittsburghPittsburgh
The Source-Receptor Challenge: Interactions The Source-Receptor Challenge: Interactions between Fine PM and Their Precursors between Fine PM and Their Precursors
NOx emissions
SO2 emissions
VOC emissions
NH3 emissions
Primary Organic emissions
Primary Inorganic PM emissions
0
5
10
15
20
25
30
35
40
Co
nce
ntr
atio
n
CrustalAmmonium
EC
Nitrate
Sulfate
Organics
PM2.5 Composition during the Winter
Ammonium Nitrate Formation
The formation of ammonium nitrate requires Nitric acid (major sources of NOx in the US are transportation and
power plants) Free ammonia (ammonia not taken up by sulfate)
The formation reaction is favored at: Low temperatures (night, winter, fall, spring) High relative humidity
Hypothesis: A significant fraction of the sulfate reduced will be replaced by nitrate when SO2 emissions are reduced.
Modeling Nitrate Partitioning
7/14 7/16 7/18 7/20 7/22 7/24 7/26 7/280
2
4
6
8
Ae
ros
ol N
itra
te (g
/m3)
Date
7/1 7/3 7/5 7/7 7/9 7/11 7/130
2
4
6
8 observed predicted
1/17 1/19 1/21 1/23 1/25 1/27 1/29 1/310
2
4
6
8
10
Ae
ros
ol N
itra
te (g
/m3)
Date
1/3 1/5 1/7 1/9 1/11 1/13 1/15 1/170
2
4
6
8
10 observed predicted
Aero
sol N
itra
te (g
m-3)
Date
Summer
Winter
Effect of Sulfate Concentration Changes on
Inorganic PM2.5
0
2
4
6
8
10
12
14
BaseCase
10% 20% 30% 40% 50%
Sulfate
Ammonium
Nitrate
Inorg
an
ic P
M2
.5 (
g m
-3)
Sulfate Reduction
Reductions of Sulfuric and Nitric Acid (Pittsburgh, July 2001)
0 10 20 30
0
10
20
30
Sulfate Reduction (%)
Inorg
an
ic P
M2
.5 R
ed
uct
ion
(%
)
Same Nitric Acid
-50% Nitric Acid-50% Nitric Acid
Reductions in Ammonia(July 2001)
0 10 20 30 40 50
0
10
20
30
40
Inorg
an
ic P
M2
.5 R
ed
uct
ion
(%
)
Ammonia Reduction (%)
20% Sulfate Reduction20% Sulfate Reduction
Reducing Inorganic PM2.5Using an observation-based model: Controls of SO2 will reduce sulfate and PM2.5
in all seasons. A fraction of the now existing sulfate will be
replaced by nitrate. The lifetime of nitrate will increase during
the summer because it will move from the gas to the aerosol phase
For Pittsburgh, ammonia controls in all seasons can minimize the replacement of sulfate by nitrate.
For Pittsburgh, NOx controls will help reduce the nitrate during the winter but they will have a small effect during the summer.
Source Apportionment of Organic Aerosol
Primary
Secondary
Anthropogenic•Gasoline•Diesel•Woodsmoke•Meat Cooking
Biogenic OrganicAerosol
Anthropogenic•Aromatic VOCs
Biogenic•Terpenes
OC
and
EC
(g
C/m
3 )
AugustJuly
0
1
2
3
4
5
6
7
8
9
10
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 2 4
OC
EC
OC and EC Measurements
•Use of 3 samplers (TQQQ, denuder-based, semi-continuous)•Five sets of measurements for EC-OC
Ozone as indicator of SOA Production
0
2
4
6
8
10
12
14
16
18
20
15-Jul 16-Jul 17-Jul 18-Jul 19-Jul 20-Jul 21-Jul
0
20
40
60
80
100
120
OC
/EC
Rat
io (
fron
t qua
rtz)
O3 (
ppb)
OC/EC RatioOzone
OC
(g
C/m
3 )
0
2
4
6
8
10
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 2July August
Daily Averaged OC Composition (July 2001)
Secondary
Primary
Monthly Average SOA
0
10
20
30
40
50
SO
A (
% O
C)
20022001
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul
Primary Biogenic Contribution
0
1
2
3
4
5
6
7
8
9
10
6/23/01 7/3/01 7/13/01 7/23/01 8/2/01 8/12/01
PM
2.5
(u
g/m
3)
OC x 1.8
Carbohydrate
Summer 01: Carbohydrate 36% of OM
0
1
2
3
4
5
6
7
8
9
10
12/26/01 1/5/02 1/15/02 1/25/02 2/4/02 2/14/02
PM
2.5
(u
g/m
3)
OC x 1.8
Carbohydrate
Winter 02: Carbohydrate 12% of OM
Sum Fall Win Spr Sum
0
50
100
150
200
250
300
0
2
4
6
8
10
12
14
16
18
Hydroxy-/Methoxy-Phenols
Levoglucosan
Le
vo
glu
co
sa
n
(ng
/m3
)
Hy
dro
xy
Me
tho
xy
Ph
en
ols
(n
g/m
3)Tracers for Woodsmoke
0
1
2
3
4
0
2
4
6
8
Alkylcyclohexanes (C19-C25)
Hopanes
Ho
pa
ne
s (
ng
/m3
)
Alk
ylc
yc
loh
ex
an
es
(n
g/m
3)
Tracers for Vehicle Emissions
Fence Line Sampling to Characterize Emissions from Coke
Facility
N
285o
225o
175o
Coke Works~ 3 miles long
Sampling Site
~1/4 mile
Coke Works Monongahela
RiverRoad
Sampling Site
~1/4 mile
Coke Works Monongahela
RiverRoad
Sampling Site
~1/4 mile
Coke Works Monongahela
RiverRoad
Sampling Site
~1/4 mile
Coke Works Monongahela
RiverRoad
Sampling Site
Coke Works Monongahela
RiverRoad
Sampling Site
“Fingerprinting” a Coke Processing Plant
1.0
0.8
0.6
0.4
0.2
0.0
959085807570656055504540353025201510
Class Vector 000000 Fraction of total particles: 0.8111 Average total signal: 74.72mV
C4H10N+C5H12N+
C3H8N+
C2H6N+CH4N+
NH+
C+
Looking at Single Particles from the Coke Facility
Single Particle Mass Spectrometry(Wexler, UC Davis)
Alkyl Amines (81% of particles)
Iron and Cerium Class from Steel Facility
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Inte
grat
ed Io
n C
urre
nt
18017517016516015515014514013513012512011511010510095908580757065605550m/z
14
12
10
8
6
4
2
0
No
rma
lize
d p
art
icle
fra
ctio
n
340320300280260240220200180160140120100806040200Wind Direction: azimuth angle
Fe+
FeO, Ce+2
Ce+CeO+
CeO2+
137o, Steel
168o
Coke174o
Coal Power
Supersite
10 miles
10-100 t/yr101-500 t/yr> 500 t/yr
PM2.5 Emissions163o
Steel
241o, Steel
293o, Coal Steam
192o
Coal Power
245o, Glass
60o
Coal Power
303o Coke &Cement
137o, Steel
168o
Coke174o
Coal Power
Supersite
10 miles10 miles
10-100 t/yr101-500 t/yr> 500 t/yr
PM2.5 Emissions10-100 t/yr
101-500 t/yr> 500 t/yr
PM2.5 Emissions
101-500 t/yr> 500 t/yr
PM2.5 Emissions163o
Steel
241o, Steel
293o, Coal Steam
192o
Coal Power
245o, Glass
60o
Coal Power
303o Coke &Cement
Wind Direction
140o
N
Typical PM Size Distribution EvolutionAugust 10, 2001
Nucleation and Growth a Few Hours After Sunrise
Nucleation and Visibility
USX Tower
USX Tower
Nucleation Frequency
0%
50%
100%
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
> 1-hr Duration < 1-hr Duration None
2001 2002
Fra
cti
on
of
Days W
ith
Nu
cle
ati
on
Significant fraction of days (30%) Most prevalent in spring, fall
0
50000
100000
150000
200000
0 25 50 75 100
Aerosol Number and MassPittsburgh, PA
2001-2002
Aerosol Mass (μg/m3)
Nu
mb
er
(#/c
m3)
10x104
20x104
Negative correlation related to nucleation activity
PM2.5 (g m-3)
0%
25%
50%
75%
100%
1 3 5 7 9 11 13 15 17 19 21 23
Composition of 10-60 nm Particles(Jimenez, U. Colorado and Worsnop,
Aerodyne)P
art
icle
Siz
e (
nm
)
10
100
500
00:00 06:00 12:00 18:00 24:00
50%
0%
100%
Mass F
racti
on
10
-60
nm
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer*
*Zhang & Jimenez (Univ. Colorado-Boulder)
Nucleation Model Evaluation (July 27, 2001)
Measured
Predicted
Nucleation and Ultrafine Particles
The model was successful in reproducing the observed behavior (nucleation or lack of) in all simulated dates in July (10) and January (10)
Strong evidence that the nuclei are sulfuric acid/ammonium/water clusters
Growth with the help of organics Discrepancies in the nucleation rates
the model tends to predict higher rates Ammonia appears to be the controlling reactant !
Small to modest reductions of ammonia can turn off the nucleation in the area especially during the summer
PMCAMx+ Modeling Domain
July 12, 2001July 17, 2001
PMPM2.52.5 Sulfate Sulfate
• 36x36 km grid, 14 levels up to 6 km• 10 aerosol sections, 13 aerosol species• 20 million differential equations• 8 CPU hours on a PC per simulation day (EQUIlibrium module)
PM2.5 Sulfate Simulation (July 2001)
SOA Simulation (July 2001)
Anthropogenic Biogenic
PMCAMx+ Evaluation in Pittsburgh
0
2
4
6
8
10
0 24 48 72 96 120 144 168
PM
2.5
NO
3 [u
g/m
3]
0
3
6
9
12
15
0 24 48 72 96 120 144 168
Simulation Hours
PM
2.5
Tota
l NH
3 [u
g/m
3]
7/12 7/13 7/14 7/15 7/16 7/17 7/18
0
10
20
30
40
50
0 24 48 72 96 120 144 168
Simulation Hours
PM
2.5
SO
4 [u
g/m
3]
0
20
40
60
80
100
0 24 48 72 96 120 144 168
Tota
l PM
2.5
mas
s [u
g/m
3]
7/12 7/13 7/14 7/15 7/16 7/17 7/18
PM2.5
Sulfate
Nitrate
Ammonium
0
3
6
9
12
15
0 24 48 72 96 120 144 168
PM
2.5
OC
[ug/
m3]
0
2
4
6
8
10
0 24 48 72 96 120 144 168
Simulation Hours
PM
2.5
EC
[ug/
m3]
7/12 7/13 7/14 7/15 7/16 7/17 7/18
OM
EC
Predicted vs. Estimated in Pittsburgh (Primary and Secondary OA)
0
3
6
9
12
15
0 24 48 72 96 120 144 168
Simulation Hours
0
3
6
9
12
15
0 24 48 72 96 120 144 168
Secondary
Primary
7/12 7/13 7/14 7/15 7/16 7/17 7/18P
redi
cted
[g
/m3 ]
Est
imat
ed [g
/m3 ]
• EC Tracer Method (Cabada et al., 2003)
PM2.5 Response (%) to 30% SO2 Emission Reduction
1 971
90
0
5
10
15
20
25
30
July 18, 2001
1 971
90
0
2
4
6
8
10
12
Concentration Change (g m-3) Percent Change
Conclusions Water is retained in the FRM filters during the days with
high sulfate and acidity The water can be estimated with a thermodynamic model
and it will decrease as sulfate decreases Large regional contributions for both sulfate and
organics Development of observation based model for the
substitution of sulfate by nitrate (requires nitric acid and ammonia measurements)
SO2 reductions will reduce sulfate and PM2.5 but nitrate will also increase in all seasons
Ammonia reductions can prevent the nitrate increase NOx reductions can help during the winter
Organic aerosol sources: Roughly 30-40% of the organic PM is secondary during the
summer (higher in worst days) and around 10% during the winter.
Evidence for significant primary biogenic PM during the summer (around 30%)
Transportation and biomass burning are the other significant sources in the area
Conclusions (continued) New technologies (Single Particle Mass
Spectrometry, semi-continuous metal measurements) allow the fingerprinting of point sources.
Frequent nucleation events (around 100 per year) At low PM concentrations Sunlight Evidence for regional scale (100-300 km) Sulfuric acid/ammonia/water nuclei Ammonia appears to be the limiting reactant for most
events Supersite data together with the results from other
studies and networks will allow us to evaluate our understanding of atmospheric PM in the US
First results of PMCAMx for summer 2001 are encouraging Consistency between 3D CTM results and observation based
models for nitrate and SOA.