Sources of PM 2.5 Carbon in the SE U.S. RPO National Work Group Meeting December 3-4, 2002

Outline Background Simplified Source Matrix Concept CMB Analysis of Primary Carbon Carbon-14 Analyses Emission Factor Approach

Carbon is an Important (often dominant) Component of PM 2.5 in the Southeast

SEARCH Measurements  Discrete Particles (24-hour) –FRM: PM2.5 –PCM and Dichot: PM2.5, PM10 and Speciation  Continuous Particles (1-min to 1-hr) –TEOM: mass –R&P 5400: OC/EC –Ammonium/Nitrate –Sulfate –Total Reduced Nitrogen -- Ammonia by Difference (under develop.)  Trace Gases (1-min) –O3, NO, NO2, NOy, HNO3, SO2, CO, CO2  Meteorology (1-min) –WS, WD, T, RH, BP, SR, rainfall  Visibility –Dry Extinction –Adsorption

(3.6) (5.0) 3.9 (3.9) FRM Equivalent PM 2.5 Organic Matter (ug/m 3 ) 10/98-9/01 Note: Project Year Begins 10/1/98, except for PNS, OLF, and OAK (in Parentheses) Begins 10/1/99.

Rural Suburban Urban Best Estimate PM 2.5 Composition 10/98-9/01 Details available at atmospheric-research.com

Best Estimate PM 2.5 Composition Centreville, AL 2000 Units are µg/m 3

Best Estimate PM 2.5 Composition Oak Grove, MS 2000 Units are µg/m3

Simplified Organic Carbon Source Matrix *e.g., Zheng et. al., ES&T, 2002; AAAR 2002.

PM2.5 Primary OC Source Identification  Investigators –Dr. Glen Cass –Ms. Mei Zheng  Description –Analyze one-month composite for each season at 8 SEARCH sites for primary organic carbon source tracers (> 100 species) –Estimate fractional contribution using CMB

Source Contributions to OC in Fine Particles

Salient Results of Primary OC Investigations Spatial coverage (SE U.S.) and temporal representativeness are limited (seasonal snapshots) –But growing! OC is virtually 100% primary in winter (all sites) Wood smoke >50% of OC in winter (all sites) –For Oak Grove > 50% winter, spring, fall OC is primary in summer (all sites)

C-14 Measurement Strategy 24-hour or 72-hour quartz filter samples, 3 sites Analyze OC/EC via TOR (DRI) Analyze C-14 via accelerator mass spectrometry (NOSAMS) Yorkville, GA –7/9/01-8/5/01 (n=6) –12/22/01-1/27/02 (n=13) Jefferson St., Atlanta, GA –7/1/01-8/21/01 (n=12) –11/13/01-1/19/02 (n=15) Oak Grove, MS –11/19/01-2/26/02 (n=18)

Carbon-14 Measurement Sites Oak Grove Centreville Pensacola Yorkville Jefferson St. N.Birmingham Gulfport OLF rural urban suburban

Carbon-14 and OC Data Atlanta, GA (JST)

Carbon-14 and OC Data Yorkville, GA

Carbon-14 and OC Data Oak Grove, MS Biomass Burning Events

Oak Grove, MS Biomass Burning Event  January 31, 2002  FRM Mass – 67.1 ug/m 3  24-Hour TEOM Mass – 66.2 ug/m 3  Anecdotal Reports of Wood Smoke

Oak Grove Event – 1/31/02  Gas and Particle data together are diagnostic of biomass burning  Continuous Speciation Data Suggest – 8% Black Carbon –<1% SO4 –<1 % NO3 – 2% NH4 –>88% Organic Matter + Water

OC Source Matrix Atlanta, GA – July 2001 * Zheng et al. Source Apportionment of Fine Particles at Atlanta, GA, AAAR 2002 Primary* Secondary Total # Modern <5 > /-5 Fossil 40* <5 41 +/-5 # from C-14 data

Source Contributions of OC in Fine Particles, 1999 Zheng et al. ES&T, % Primary 64% Modern

OC Source Matrix Atlanta, GA – January 2002 * 1999 Data: Zheng et al., ES&T, Primary* Secondary Total # Modern 64 <5 61 +/-5 Fossil 36 <5 39 +/-5 # from C-14 data

Source Contributions of OC in Fine Particles, 1999 Zheng et al. ES&T, % Primary 16% Modern

OC Source Matrix Yorkville, GA – July 2002 * 1999 data: Zheng et al. ES&T, Primary* Secondary Total # Modern /-6 Fossil 16 <5 17 +/-5 # from C-14 data

Source Contributions of OC in Fine Particles, 1999 Zheng et al. ES&T, % Primary 86% Modern

OC Source Matrix Oak Grove, MS – February 2002 * 1999 data: Zheng et al. ES&T, Primary* Secondary Total # Modern 86 < /-5 Fossil 14 <5 5 +/-5 # from C-14 data

Emission Factor Approach Use difference between Urban and Biomass signatures to label and quantify source contributions of EC and TC Label sources using CO/NOy ratios (2 source assumption) Quantify contributions based on EC/CO and TC/CO ratios

Emission Factor (EF) Calculations [x] event - [x] background [tracer] event – [tracer] background EF = where x is component of interest and tracer is CO. EFs conveniently calculated by linear regression.

Example Total Carbon EF Atlanta SuperSite Experiment TC = 11.3*CO R 2 = CO (ppm) TC (ug/m3)

Urban and Biomass EFs are Very Different NOy/CO (ppb/ppm) PM2.5/CO (ug-m -3 /ppm) TC/CO (ug-m -3 /ppm) Urban Biomass Urban/Biomass Ratio

Emission Factor Calculations Centerville, AL – CY2000 EF calculations suggest EC and TC >80% Biogenic AND yield reasonable F-Modern, BUT tend to overpredict TC, esp. in winter

Summary & Conclusions Work in Progress, but results show convergence among techniques Zheng and Cass primary carbon work shows almost all OC primary in winter, % primary in summer Also show wood smoke makes up >50% OC in winter (detectable all seasons) C-14 data show OC is predominantly modern for all sites and all seasons. Urban site exhibits more fossil OC than rural sites. No evidence of strong summer/winter seasonality in modern/fossil OC, but an interesting step to >95% modern observed in MS during January 2002 (biomass burning?). Emission Factor calculations suggest EC and TC mostly biomass (>80%), but overpredict TC Combination of techniques permits semi-quantitative completion of source matrix