Descriptive Model of PM Pollution in Baltimore · 2015-08-28 · Descriptive Model of PM Pollution...
Transcript of Descriptive Model of PM Pollution in Baltimore · 2015-08-28 · Descriptive Model of PM Pollution...
Descriptive Model of PM Pollution
in Baltimoreas derived from
Analysis of Components of Discrete Episodes at
the Ponca St. Supersite
John Ondov
Department of Chemistry and Biochemistry
University of Maryland, College Park, MD 20742
[email protected]; 301 405 1859
www.chem.umd.edu/supersite
Baltimore Supersite Study Area
C u r t is C r e e k C lu s te r
A t o c h e m
R e n d e r in g p a n t C o a s t G u a r d
Typical MidAtlantic Seaport CityPopulous, heavy industry, So. BaltimoreComplex meteorology
Major N.-S. transportation corridor
End member Washington - Boston Megalopolis
Variable Aerosol agelocal, 50 km, 100’s km source regionsAppalachian Cloud-processed sulfate
Environmental JusticeDowntown, weakly influencedSo. Baltimore 10-X PAH, Metals
1.7-X deaths via pulmonary disease
Interpretive Context25 yrs receptor modeling in regionEPA and AEOLOS studies in BaltimoreIMPROVE site, Shennandoah Nat. Park
Health Effects StudiesJHU & UMAB
Strategically located to assess urban,
industrial, and traffic influences
Industrial Sector
30o
Measurements
– Primary Site: Ponca St., East Baltimore9.5 months: March – November, 2003
– Maximum temporal, size, compositional resolution• PM2.5, EC,OC, Nitrate, Sulfate,
• Metals, Organic compounds
• PAMS VOC, CO, NOx, NO, NO2, O3
• LIDAR, Single Particle MS
• SMPS + APS size distributions 10 nm to 20 µm
– Measurement resolution 5 min, 10 min, 30 min, 1 hr, 3 hr,plus 24 Hr FRM mass and speciation
Interpretive Context
• PM air pollution may be viewed as occurring in a series of
discrete meteorologically driven discrete episodes
• Transients often caused by one or two components
• Local vs. distant sources indicated by
– Temporal behavior of constituents and marker species
– Size distribution parameters
– Detailed Analysis of episodes
Outline
• PM2.5 Episodes in 2002 (30 min data)
• Summary of major features of 6 worst
• Detailed description of highly time resolved data
for worst summer and cool weather episodes
• Features of major components
Mar Mar Apr Apr Apr
PM2.5, µg/m3
0
20
4060
80
100
Aug Aug Sep Sep Sep
PM2.5, µg/m3
0
20
40
6080
100
Oct Oct Nov Nov Dec Dec Dec
PM2.5, µg/m3
0
20
4060
80
100
May May Jun Jun Jul Jul Jul
PM2.5, µg/m3
020
40
60
80
100
30-minPM2.5 Concentrations: 2002show: series of discrete episodes of hours to 2 or 3 days duration
reconstructedA B C
D
EF
Canadian
Smoke
PM2.5 Statistics: 9.5 months, 2002
w/Canadian w/o Canadian
Smoke Smoke*
Daily means: 3.5 to 85.6 3.5 to 64
Annual mean 16.9 15.8±13
No. daily exceedences 2 ~1
No. daily means > 30 µg/m3 29
(i.e., 16.9 + 13)
*Episode B; M\maximum 30 min concentration was 198 µg/m3
6 worst episodes described in Park et al., 2005
2 will be described in this talk
Ozone (ppb) Ambient temp (°C) Relative humidity (%)Maxima NOx and CO,
ppb
Episode Date Type Avg. Range Avg. Range Avg. Range NOx CO
A June 24-25 Regional Haze 84 26-132 29.8 23.7-35.4 57.5 32-77 110 800
B July 6-8 Canadian Smoke - - 25.6 19.7-33.8 45.4 28-70 155 1600
C July 18-19 Regional Haze 70 14-91 29 23.2-34.0 57.9 38-81 130 800
D Aug.12-14Reg Haze + Local
Traffic 76 22-122 29.2 21.6-35.6 53.8 35-79 300 1800
E Oct. 2-5 Regional Haze 35 1-57 24.8 17.5-30.4 69.2 36-91 180 1300
F Nov. 20-21 Local Traffic 2 0-6 8.4 3.1-14.5 83.2 48-98 780 2800
Ozone mixing ratios represent measurements made between 10:00 and 20:00 hours.1
1
Characteristics of Six Worst PM2.5 Episodes
Baltimore Supersite, Ponca St., 2002
Episode durations: 2 to 4 days
Summer haze: high O3, hot, low NOx & CO
Fall local sources: low O3, cool, high NOx & CO
Concentrations
Table 2. Concentrations of PM2.5 mass and major chemical species for 6 pollution episodes.
PM2.5, µg/m³ Constituent expressed as indicated, µg/m³
Episode Interval TEOM Reconstructed (NH4)2SO4 OM EC NH4NO3
A Episode Avg.¹ N/A 55¹, 62² 36 16 1.2 1.7
Regional Haze Episode Range¹ 43 - 77 28 - 60 11 - 22 0.6 - 2.8 0.6 - 5.2
Bkgnd³ N/A 24 8.3 12 1.1 0.65
Bkgnd Range 22 - 27 5.8 - 10 11 - 14 0.6 - 2.3 0.6 - 0.7
B Episode Avg. 57¹, 86² 55¹, 82² 6.9 54 1.9 2.1
Canadian Smoke Episode Range¹ 20 - 180 20 - 174 3.7 - 13 14 - 161 0.5 - 3.7 0.25 - 5.4
Bkgnd³ 19 18 4.6 12.6 0.5 0.27
Bkgnd Range 15 - 17 17 - 19 2.7 - 6.2 10 - 15 0.4 - 0.5 0.2 - 0.3
C Episode Avg.¹ 49¹, 52² 48¹, 52² 34 11 1.0 1.0
Regional Haze Episode Range¹ 24 - 72 27 - 65 12.5 - 49 7.1 - 15.6 0.4 - 2.7 0.6 - 2.2
Bkgnd³ 23 23.5 10.4 10.7 1.0 1.4
Bkgnd Range 12 - 37 14 - 33 3.5 - 16.5 6.4 - 15 0.5-3.1 0.4 - 1.2
D Episode Avg.¹ 42¹, 57² 39¹, 53² 20 16 1.5 1.6Reg Haze +
Local Traffic Episode Range¹ 36 - 73 14 - 68 3.4 - 42 8 - 29 0.6 - 6.4 0.4 - 5.2
Bkgnd³ 11 13 4.6 7.5 0.7 0.7
Bkgnd Range 9.8 - 12.5 12.9 - 14 3.2 - 6 7.1 - 8 0.7 - 0.9 0.4 - 1.1
E Episode Avg.¹ 35¹, 35² 32¹, 35² 21 9.1 2.0 1.9
Regional Haze Episode Range¹ 8.9 - 52 11 - 47 14 - 28 6.9 - 15 1.1 - 3.3 0.5 - 6.0
Bkgnd³ 12 14 5.7 6.2 1.0 0.9
Bkgnd Range 6.5 - 22 8.1 - 22 3.5 - 7.5 3.8 - 11 0.4 - 2.5 0.3 - 2.4
F Episode Avg.¹ 32¹, 32² 34¹, 32² 7 14 3.3 8.9
Local Traffic Episode Range¹ 9.1 - 87 14.5 - 83 4.4 - 11 5.2 - 55 1.2 - 12 3.6 - 15
Bkgnd³ 9.6 14 4.7 4.8 1 3.2
Bkgnd Range 7,8 - 12 13 - 14 4.2 - 5.0 4.7 - 5.1 0.8 - 1.1 2.5 - 4.3
¹Average concentration during period of elevation
²Highest midnight to midnight (24-hr) average during episode
³Average before and after episode
Estimated, see text.4
4
PM2.5, µg/m3
bkgnd mean
* Summer ~20 ~60
Fall ~ 14 ~34
•Summer more sulfate
Fall comparable OM
more EC, nitrate
Table 3. Relative Composition of PM2.5
Table 3, continued.
PM Episode A
June 24-26, 2002
Summer Haze Episode, dominated by Sulfate,OM
Influence of Local sources evident
Type A
Measurement period
06/24/02 06/25/02 06/26/02
Win
d s
pee
d (
m/s
ec)
0
1
2
3
4
5
6
7
8
Win
d d
irec
tion
(d
eg)
0
40
80
120
160
200
240
280
320
360
400
Wind speed
Wind direction
Episode A: June 24-25: Sulfate Haze Event
T y p e A
M e a s u r e m e n t p e r i o d
0 6 / 2 4 / 0 2 0 6 / 2 5 / 0 2 0 6 / 2 6 / 0 2
Recon
stru
cte
d P
M2
.5 m
ass
(µµ µµ
g/m
3)
0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
1 0 0
Su
lfate
an
d O
C c
on
c (µµ µµ
g/m
3)
0
5
1 0
1 5
2 0
2 5
3 0
3 5
4 0
4 5
5 0
P M 2 .5 m a s s
S u l f a t e
O r g a n i c c a r b o n
Worst Episode in 9.5 month study (except Canadian Smoke)
Aged Local, regional, fresh local components
•1.5 hrs after local
winds shift to 170o
at 3m/s = 16.2 km
•Local power plant 15
km plumes raise sulfate
concs. ∆∆∆∆15 µg/m3
Local power plants 44 - 31 = 13 µg/m3
B
Inter-regional transport 31 - 6 = 25 µg/m3
A
Aged Local, 24 - 6 = 18 µg/m3P
M2.5mass, µg/m
3
Episode A
Particle diameter (nm)
10 100 1000 10000
dN/dlogDp (x104 #/cm
3)
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
3.0
June 25 (24 h avg)
1800 EST June 25
Fresh power plant accumulation mode
Aged secondary accumulation mode
18:00 06/25
24-hr avg
Bkgnd, 6 µg/m3
Bkgnd
Background A Stagnation
B Transport
Event Done
Some important points
• Arguably, sources in the local region contributed
substantial amounts of sulfate on day1
• Arrival of polluted air mass increases sulfate 7x
relative to background on day 2
• OC increase only 1.5x over background, to 10
µg/m3.
Whereas for Episode F, local (traffic) induces 3x
increase in OC!
Influence of Traffic
revealed by
characteristic size spectra, diurnal profiles
show
EC, OC, Nitrate from traffic emissions heavily influence
PM2.5 in cool, moist, low-mixing height periods
i.e., Fall, Winter, Night time
LA: Size Distributions for motor vehicle traffic3 narrow modes in ultrafine size range
Evolution w/distance
Size distribution indistinguishable
from upwind at 300 m downwind
30 m downwind - trimodal
Fresh automobile aerosol Peaks
Modal diameter changes with distance
due to evaporation/condensation of
volatiles
Source: LA Supersite/PM center, Sioutas
Baltimore: Ultrafine particles indicate traffic in AM
Any day, most any wind direction!Less pronounced in afternoon, longer rush hour, greater mixing height and wind speeds
-
Tuesday
Sunday
Sunday
Monday
Feb 18
Tuesday
Feb 19
Wednesday
Feb 20
Thursday
Feb 21
Monday morning
Holiday
FridayFeb 22
Leaving work
early
0:00 06:00 12:00 18:00 24:00
10:00 PM
10
100
0:00 06:00 12:00 18:00 24:00
10
100
Size, nm
Size, nm
06:00 12:00 18:00 06:00 12:00 18:00 06:00 12:00 18:00
W h o le p e r io d
T im e o f t h e d a y ( h r )
- 1 0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4
OC (µg C/m
3)
2 .0
2 .5
3 .0
3 .5
4 .0
4 .5
5 .0
5 .5
6 .0
6 .5
7 .0
7 .5
8 .0
EC (µg C/m
3) or CO(x2 ppm)
0 .4
0 .6
0 .8
1 .0
1 .2
1 .4
1 .6
1 .8
2 .0
2 .2
O C
E C
C O
O C -E C
M e a s u r e m e n t p e r io d
0 8 /1 1 /0 2 0 8 /1 2 /0 2 0 8 /1 3 /0 2 0 8 /1 4 /0 2 0 8 /1 5 /0 2
OC
(µµ µµ
g C
/m3
)
0
2
4
6
8
1 0
1 2
1 4
1 6
1 8
2 0
EC
(µµ µµ
g C
/m3
)
0 .0
0 .7
1 .4
2 .1
2 .8
3 .5
4 .2
4 .9
5 .6
6 .3
7 .0
O C
E C
Baltimore Ponca St: EC – Strong Diurnal CyclesPeaks correspond to morning Traffic
Average daily profile
(9.5 months)
Even in August
OC
EC
COOC:EC ratio increases
evenings & early AM
Night-time chemistry?
5:1
5:1
3:1
Baltimore Air is Heavily influenced by Traffic(Especially in Fall/Winter/Spring months)
Ultrafine particles
peak at morning
rush hour (6:00 –
9:00 AM)
E-SE winds
4hr average data
Sampling date
04/16/02 04/17/02 04/18/02
% o
f (S
O4 +
NO
3 +
EC
+ O
M) in
PM
2.5
0
10
20
30
40
50
60
70
80
90
100
SO4%(4h)
NO3%(4h)
EC%(4h)
OC%(4h)
Sampling period
04/16/02 04/17/02 04/18/02
TEO
M m
ass c
onc (ug/m
3)
0
10
20
30
40
50
60
70
80
Org
anic
carb
on c
onc (ug/m
3)
0
2
4
6
8
10
12
14
16
TEOM
Organic C
OC highly correlated w/TEOM
Sampling period
04/16/02 04/17/02 04/18/02
SM
PS #
conc (#/c
m3)
2e+4
4e+4
6e+4
8e+4
1e+5
Ele
menta
l carb
on c
onc (ug/m
3)
0
1
2
3
4
5
6
7
8
9
SMPS
Elemental C
OC & EC highly correlated
w/morning traffic peak
OC a substantial fraction of PM2.5
15 nm -
Nitrate is more complicated
NOx converted to nitrate 10x faster than SO2 to sulfate,
therefore local sources much more important for nitrate
NH4NO3 dissociation equilibrium favors nitrate at low
T, high RH
Night time radical chemistry forms nitric acid from NO2
when temperatures are typically cooler and RH higher
Monthly trend of Nitrate concentration at Ponca
Sampling period (month)
EntireFeb Mar April MayJune July Aug Sep Oct Nov
Nitra
te c
onc (ug/m
3)
0
1
2
3
4
5
Monthly data
Lower concentrations in summer when ammonium nitrate more volatile
#concentration (“pure nitrate”
50~90nm particle)
May 5 peak May 6 morning
peak
May 3-8, 2002
R&P 8400N
“Pure” Nitrate particles correlate with PM2.5 Nitrate peaks:
occur at high RH, low temperatures
RSMSIII
Tolocka et al., Submitted
These data suggest
that much of the
nitrate is formed by
nucleation of new
particles!
1 3 5 7 9 11 13 15 17 19 21 23
1280
770
440
230
140
110
90
50
45
Percentage of Total Spectra
Time (hr)
Aerodynamic Diameter (nm)
Nitrate Class April 16th, 2002
10.0%-11.0%
9.0%-10.0%
8.0%-9.0%
7.0%-8.0%
6.0%-7.0%
5.0%-6.0%
4.0%-5.0%
3.0%-4.0%
2.0%-3.0%
1.0%-2.0%
0.0%-1.0%
Fraction of Particles in Nitrate Class vs. Size / Time of DayBut other times – much forms on “droplet” mode
Weekend patterns
Saturday
Feb. 23
Sunday
Feb. 24
Saturday night
entertainment traffic or
Night time chemistry?
Bars close 2:00 AM
W in d d ir e c t io n (d e g )
0 3 0 6 0 9 0 1 2 0 1 5 0 1 8 0 2 1 0 2 4 0 2 7 0 3 0 0 3 3 0 3 6 0
Nitra
te c
onc (ug/m
3)
0
2
4
6
8
1 0
1 2
1 4
1 6
1 8
W in d s p e e d (m /s e c )
0 1 2 3 4 5 6 7 8
W in d d ire c t io n
W in d s p e e d
I-895N/I-95N
Locally Produced Nitrate concentrations frequently
observed at 30o and at wind speeds 0 to 1 m/s
30o
Example: March 23 – 25 data
Park et al., Atmos. Environ. 39:2011, 2005:
32% of Nitrate transients were > 1 µg/m3
64% w high/NOx between 5 – 8 AM
26% between 10 PM – 2 AM
E p iso d e F
M easu rem en t p e riod
1 1 /1 9 /02 11 /20 /02 1 1 /21 /02
Ambient temp (oC)
0
2
4
6
8
10
12
14
16
18
20
Relative humidity (%)
2 0
3 0
4 0
50
60
70
80
90
100
Am b ien t tem p
RH
Episode F: November 20, 21Cool Temperatures, Morning RH >90%
Winds light, variable on 20th,
Winds light, 30o, very high RH, on 21st
E pisode F
Measurement period
11/19 /02 11 /20/02 11 /21 /02
Wind speed (m/sec)
0
1
2
3
4
5
6
7
8
Wind direction (deg)
0
40
80
120
160
200
240
280
320
360
400
Wind speed
W ind dir
90%
RH
Power
Plant
30o
E pisode F
Measurement period
11/19 /02 11 /20/02 11 /21 /02
Wind speed (m/sec)
0
1
2
3
4
5
6
7
8
Wind direction (deg)
0
40
80
120
160
200
240
280
320
360
400
Wind speed
W ind dir
Episode F: November 20, 21E p isode F
Measurement period
11 /19 /02 11/20/02 11/21 /02
PM
2.5 m
ass and OC conc ( µg/m
3)
0
10
20
30
40
50
60
70
80
90
100
EC and nitrate conc ( µg/m
3)
0
2
4
6
8
10
12
14
PM2.5 mass
O rganic carbon
E lemental carbon
N itrate
E pisode F
Measurement period
11/19 /02 11 /20/02 11 /21/02
Hourly NOx conc (ppb)
0
100
200
300
400
500
600
700
800
900
1000
Hourly CO conc (ppm)
0 .0
0 .3
0 .6
0 .9
1 .2
1 .5
1 .8
2 .1
2 .4
2 .7
3 .0
NOx
CO
Episode F: November 20, 21Cool Temperatures, Stagnation, High RH, morning traffic peak;
Nitrate deposits on wet particles;
Winds from 30o all day on 21st Nitrate (lags NOx)
Highest
PM2.5 max
No obvious
power plant
influence;
mixing hgt
too low
Episode F : well correlated EC, OC, PM2.5 (Local traffic): Max conc
Episode 4 (Nov 20)
Measurement period
11/19/02 11/20/02
TEO
M P
M2.5 m
ass c
onc (ug/m
3)
0
12
24
36
48
60
72
84
96
108
120
TEOM time series (30 min)
3 hr running avg
Episode F
Measurement period
11/19/02 11/20/02
Ele
menta
l carb
on c
onc (ugC
/m3)
0
1
2
3
4
5
6
7
8
9
10
Org
anic
carb
on c
onc (ugC
/m3)
0
4
8
12
16
20
24
28
32
36
EC (1hr)
OC (1hr)0
12
24
36
48
60
72
84
96
108
120
11/2
0/02
0:0
0
11/2
0/02
1:0
0
11/2
0/02
2:0
0
11/2
0/02
3:0
0
11/2
0/02
4:0
0
11/2
0/02
5:0
0
11/2
0/02
6:0
0
11/2
0/02
7:0
0
11/2
0/02
8:0
0
11/2
0/02
9:0
0
11/2
0/02
10:
00
11/2
0/02
11:
00
11/2
0/02
12:
00
11/2
0/02
13:
00
11/2
0/02
14:
00
11/2
0/02
15:
00
11/2
0/02
16:
00
11/2
0/02
17:
00
11/2
0/02
18:
00
11/2
0/02
19:
00
11/2
0/02
20:
00
11/2
0/02
21:
00
11/2
0/02
22:
00
11/2
0/02
23:
00
Measurement period
PM
2.5 m
ass contribution (ug/m
3) Undetermined
OrganicsEC(NH4)2SO4NH4NO3
Episode F
Winter stagnation
(OC +EC)
TEOM (µg/m3) = 2.57 OC (µg/m3) + 10.53 R2=0.88
TEOM (µg/m3) = 7.39 EC (µg/m3) + 13.92 R2=0.85
Summary
• 24-hr PM2.5 standard rarely exceeded during 2002 at Ponca st. –Episode A, max 24-hr PM2.5 was ~65 ug/m3
• 9.5-month 30-min average barely exceeded annual PM2.5 standard.
• Episodes occur during periods of stability/stagnationSummer episodes caused by stationary fronts; end by break by passage of cold fronts
• Local sources – traffic; So. Baltimore industry; and local regional sources contribute substantially, to EC, OC, Nitrate, especially in fall, winter, spring
• Major summer haze events; dominated by sulfate & OC – worst event after air stagnant over Ohio Valley arrived in Baltimore w/local wind direction from So. Baltimore; but Local So. Baltimore sources contributed ≥5% of PM2.5 – enough to trip standard
• Urban traffic corridor creates PM “hot spots.”