EPA Precursor Gas Training Workshop

PM2.5 Chemical Speciation Network (CSN) Carbon Conversion

Joann Rice

EPA Precursor Gas Training Workshop

PM2.5 Speciation Carbon Conversion

• PM2.5 Chemical Speciation Network (CSN):– Speciation Trends Network (STN)

• 54 Trends sites: Largely static urban monitoring stations and protocols for sampling and analysis

– State and Local Air Monitoring Stations (SLAMS)• Currently ~150 sites: monitors for state and local agency

directed monitoring objectives

• Changes in the network to address inconsistencies in carbon sampling and analysis procedures used in urban CSN and rural IMPROVE programs– Field blank collection and subtraction also changing

EPA Precursor Gas Training Workshop

Carbon Data Comparability Issues

• A Brief History…– Factor of 2 difference in Elemental Carbon (EC) highlighted

by Chow et al., 2001*– Data users comparing urban (speciation) and rural

(IMPROVE) monitoring data for modeling, air quality data analyses, control strategy development, …

– Question posed to CASAC on strengths and weaknesses of converting the network (December 2004)

– The CASAC subcommittee on monitoring strongly recommended changes to the network “to achieve fully comparable data”

– EPA/OAQPS began communicating plans for changes to carbon in late 2004

* Chow, J.C., Watson, J.G., Crow, D., Lowenthal, D.H., and Merrifield, T. (2001). Comparison of IMPROVE and NIOSH Carbon Measurements; Aerosol. Sci. and Tech. 34:23-34.

EPA Precursor Gas Training Workshop

• A Brief History…–15 City CSN-to-IMPROVE

comparison study• Preliminary data analysis from first 6 cities

– ORD/OAQPS analysis of first year data in 2003 and OAQPS reassessment of full data set in 2005

– Factor of 2 not observed for EC in urban locations; however, bigger differences found for EC in rural locations

– Significant differences in OC observed due to filter face velocity/flow rate

• Results from additional 9 sites not yet evaluated

Carbon Data Comparability Issues

EPA Precursor Gas Training Workshop

Organic Carbon Comparisonsite=Haynes Pt

IMPROVE STN IMPROVE STN IMPROVE STN IMPROVE STN

0

5

10

15

20

Con

cent

ratio

n

OC

Fall Spring Summer Winter

site=Dolly Sods

IMPROVE STN IMPROVE STN IMPROVE STN IMPROVE STN

0

1

2

3

4

5

6

7C

once

ntra

tion

OC

Fall Spring Summer Winter

parm=OC (Imp or STN)

PLOT Haines Point (urban) Haines Point Deming LineDolly Sods (rural) Dolly Sods Deming Line

IMP

RO

VE

0

5

10

15

20

STN

0 5 10 15 20

• Sampler and filter-face velocity effects due to flow differences

• IMPROVE ~22 LPM; and MetOne ~ 7 LPM

• IMPROVE OC un adjusted for blank

EPA Precursor Gas Training Workshop

Elemental Carbon Comparison

parm=EC (Imp or STN)

PLOT Beacon Hill (urban) Beacon Hill Deming LineMt. Ranier (rural) Mt. Ranier Deming Line

IMP

RO

VE

0

1

2

3

4

5

STN

0 1 2 3 4 5

site=Mt. Ranier

IMPROVE STN IMPROVE STN IMPROVE STN IMPROVE STN

0

0.2

0.4

0.6

0.8

1.0

Con

cent

ratio

n

EC

Fall Spring Summer Winter

• EC compares better in urban areas, but large amount of scatter

• Rural EC at lower concentrations <0.3 µg/m3

site=Beacon Hill

IMPROVE STN IMPROVE STN IMPROVE STN IMPROVE STN

0

1

2

3

4

Con

cent

ratio

n

EC

Fall Spring Summer Winter

EPA Precursor Gas Training Workshop

Sampling and Analysis

• URG3000N Carbon Sampler– Identical to the IMPROVE sampler except:

• Mass flow control• Sampler operation and troubleshooting support provided by

URG• Modules loaded/provided by RTI

– Differs from CSN sampler• 22.8 LPM flow rate• 25-mm Pallflex Quartz filter

• Carbon Analysis– IMPROVE_A TOR method– Blank collection and subtraction

EPA Precursor Gas Training Workshop

PM2.5 Speciation Carbon Conversion

• EPA is using a contractor to procure, install and train operators on URG3000N sampler use

• The contractor coordinates installation with Region/State agencies

• Once installations are complete, new TOR analysis begins – All sites move to TOR at once– Concurrent CSN TOT and new sampling and TOR analysis

done for about two months

• Sampling modules, cassettes, and analysis will continue to be supported and supplied by RTI

• Repeat process for rest of the network in batches of 50-60

EPA Precursor Gas Training Workshop

Project Status

• Phase I completed May 2007– May 3rd start date

• Phase 2 site selection starting now– Expect fall 2007 installation start date

• URG3000N web page created– http://epa.gov/ttn/amtic/specurg3000.html

• Issues and Problems so far:– Few sites not prepared for installation (space and

power issues)– Handful of sampler startup issues– Some agencies without FTS to check 22 LPM– Lead time on parts/supplies from vendor

EPA Precursor Gas Training Workshop

Questions