semi-continuous measurements of pm2.5 carbon at the south ... · pm 2.5 carbon • constitutes...

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


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 )


24 hr SUNSET vs STN Filter Total Carbon


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 )


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


µg/m

3 ,

mean median


Seasonal Variation

Monthly SUNSET EC, South Bronx, 2005-2006

0

1

2

3

4

5


µg/m

3 ,

mean median


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

semi-continuous measurements of pm2.5 carbon at the south ... · pm 2.5 carbon • constitutes...

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