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Semi-Continuous Measurements of PM2.5 Carbon at the South Bronx, New York:
Comparison with Filter Measurements
Oliver V. Rattigan, Dirk Felton, Paul SierzegaNew York State DEC – BAQS
Jim SchwabASRC, University at Albany, SUNY
2006 National Monitoring Conference - November 7, 2006
PM2.5 Carbon• Constitutes ~30-50% of PM2.5 mass in New
York City.• Elemental Carbon (EC)-(Black carbon, BC);
– Direct emission from fuel combustion (pyrolysis of organic carbon).10-20% of TC.
• Organic Carbon (OC)- Major fraction.– Primary-direct emission from combustion
processes, cooking, industrial processes, biogenic sources
– Secondary-(SOA), VOC photo-oxidation products • Inorganic Carbon- carbonates, CaCO3.
(limestone, dust) – not observed in New York City.
South Bronx, IS52- (681 Kelly St.).
Inlets for Semi-Continuous Analyzers
IMPROVE Sampler
STN Sampler (R&P)
SUNSET Carbon
•PM2.5 cyclone
•SS Inlet
•Denuder (activated carbon strips)
•Quartz filter collects sample
•Hourly OC, EC
•Thermal conversion to CO2
•NDIR Detection
SUNSET Labs EC/OC Carbon Analyzer
Filter Measurements•24 hr, 1 in 3 Day Schedule, Quartz filter
•R&P 2300 Partisol (end 1/11/06), 10LPM, 14.4 m3
•Met-One SASS ( beg. 1/14/06), 6.7LPM, 9.6 m3
sharp cut cyclone
Silicon greased impactor
Flow Characteristics of Sunset Analyzer• Sunset Labs ECOC, 47 min samples, 8
li/min, ~0.4 m3 per sample
Comparison of Filter Face Velocities
•Sunset: ~ 80 cm/s
•R&P Partisol 2300 (24-hr filter): ~9.6 cm/s
•MetOne SASS (24-hr filter): ~6.4 cm/s
Measurement of “blank” or positive artifact for Sunset
Organic Carbon Blank, Jan 25-27, 2006
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
1/25 12:00 1/25 18:00 1/26 0:00 1/26 6:00 1/26 12:00 1/26 18:00 1/27 0:00 1/27 6:00 1/27 12:00
µg/m
3 ,
OC = 0.54 µg/m3, sd 0.29
Mean and Std Dev. SUNSET Hourly OC Blanks, South Bronx
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
Aug-05
Sep-05
Oct-05
Nov-05
Dec-05
Jan-06
Feb-06
Mar-06
Apr-06
May-06
Jun-06
Jul-06
Aug-06
Sep-06
µg/m
3 ,
total hourly average = 0.68
Elemental Carbon Blank, Jan 25-27, 2006
-0.010
-0.008
-0.006
-0.004
-0.002
0.000
0.002
0.004
0.006
0.008
0.010
0.012
1/25/ 12:00 1/25/ 18:00 1/26/ 0:00 1/26/ 6:00 1/26/ 12:00 1/26/ 18:00 1/27/ 0:00 1/27/ 6:00 1/27/ 12:00
µg/m
3 ,
EC = -0.004 µg/m3, sd 0.003
Mean and Std. Dev. SUNSET Hourly EC Blank, South Bronx
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
Aug-05
Sep-05
Oct-05
Nov-05
Dec-05
Jan-06
Feb-06
Mar-06
Apr-06
May-06
Jun-06
Jul-06
Aug-06
Sep-06
µg/m
3 ,
Comparison of Semi-Continuous Sunset to STN Filter Measurements of EC & OC
Blank or positive artifact corrections are applied to the STN data based on averages of field and trip blanks at the South Bronx site. (Averages are done separately for R&P and MetOne samplers.)
24Hr SUNSET vs STN Filter Elemental Carbon
Partisoly = 0.87x + 0.03
R2 = 0.59
Met Oney = 0.86x - 0.14
R2 = 0.96
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0
STN Filter EC (µg/m3)
SUN
SET
EC (µ
g/m
3 )
Partisol Met-One Linear (Partisol) Linear (Met-One)
24 hr SUNSET vs STN Filter Organic Carbon
Partisoly = 0.66x + 0.45
R2 = 0.69
Met-Oney = 0.67x - 0.17
R2 = 0.86
0
2
4
6
8
10
12
14
0 2 4 6 8 10 12 14
STN Filter OC (µg/m3)
SUN
SET
OC
(µg/
m3 )
Partisol Met-One Linear (Partisol) Linear (Met-One)
24 hr SUNSET vs STN Filter Total Carbon
Partisoly = 0.73x + 0.43
R2 = 0.65
Met-Oney = 0.73x - 0.35
R2 = 0.92
0
2
4
6
8
10
12
14
16
18
20
0 2 4 6 8 10 12 14 16 18 20
STN FIlter TC (µg/m3)
SUN
SET
TC (µ
g/m
3 )
Partisol Met-One Linear (Partisol) Linear (Met-One)
Seasonal and Day-of-Week Patterns from Sunset Data
Monthly SUNSET Total Carbon, South Bronx, 2005-2006
0
2
4
6
8
10
12
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
µg/m
3 ,
mean median
whiskers indicate 5 and 95 percentiles
Seasonal Variation
Monthly SUNSET OC, South Bronx, 2005-2006
0
1
2
3
4
5
6
7
8
9
10
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
µg/m
3 ,
mean median
whiskers indicate 5 and 95 percentiles
Seasonal Variation
Monthly SUNSET EC, South Bronx, 2005-2006
0
1
2
3
4
5
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
µg/m
3 ,
mean median
whiskers indicate 5 and 95 percentiles
Seasonal Variation
Ratio OC/EC 2005-2006, South Bronx
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Jul-05
Aug-05
Sep-05
Oct-05
Nov-05
Dec-05
Jan-06
Feb-06
Mar-06
Apr-06
May-06
Jun-06
Jul-06
Aug-06
Sep-06
Month,
OC
/EC
,
Organic Carbon, 2005-2006, South Bronx
0
0.5
1
1.5
2
2.5
3
3.5
4
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
µg/m
3 ,
weekday weekend
Day-of-Week Variation
Elemental Carbon, 2005-2006, South Bronx
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
µg/m
3 ,
weekday weekend
Day-of-Week Variation
Example of the Power of Continuous Measurements for PM2.5 Mass Reconstruction
•PM2.5: TEOM - 50º C “standard”
•Sulfate: Thermo 5020 – Values x 1.375 to account for ammonium
•Nitrate: R&P/Thermo 8400N – Values x 1.29 to account for ammonium
•OM: OC x 1.5
•EC: used as measured
Nov 2005
0
10
20
30
40
50
6011
/1
11/3
11/5
11/7
11/9
11/1
1
11/1
3
11/1
5
11/1
7
11/1
9
11/2
1
11/2
3
11/2
5
11/2
7
11/2
9
12/1
µg/m
3
PM2.5 SO4+TC+NO3 FRM
SO4 = (NH4)2SO4
NO3 = NH4NO3
TC = OC *1.5 + ECPM2.5 = 50oC TEOM
Method Issues - Sunset• Stable measurement of positive
artifact (“blank”) requires ~24 hours• Variability of OC positive artifact –
use annual, seasonal, or monthly values?
• Collection of SVOC – front oven cool down time, and ~30º C Filter Temp.
• Carbon paper denuder – are activated carbon monoliths more appropriate?
• Should we use Optical or Thermal EC? What do we do with the other?
Conclusions - Artifacts
• Artifacts (blanks) are an issue• No clear solution:
– Improve “correction” scheme– Improve method (i.e., eliminate issue)– ???
Conclusions – Filter Comparisons
• Mixed results– EC okay (<15% difference)– OC less good (>30% difference)
• How do we know which is right? (i.e., STN or Sunset)– STN – no denuder– Sunset – SVOC loss?– Need calibration “standards”
• Is there a “monitoring” method that can quantitatively collect SVOC?
Conclusions - Observations
• OC concentrations are highest from June to August
• EC appears to be a little higher in winter (as expected)
• Day-of-week dependence is weaker then expected. EC shows greater contrast for most months.
Acknowledgements
• Rich Colas and Sergio Fleishaker for help with instrument operation at IS52
• ASRC colleagues Ken Demerjian and Olga Hogrefe