IS IT OR IS IT SMOKE? Beyond visual observation we cannot differentiate between smoke and any other organic aerosol.

Transcription

1 IS IT OR IS IT SMOKE? Beyond visual observation we cannot differentiate between smoke and any other organic aerosol.

2 WHY DO WE NEED TO APPORTION ORGANIC AERSOLS PM2.5 STANDARD REGIONAL HAZE RULE

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7 Great Smoky Mountains National Park

8 HOW ARE AEROSOLS APPORTIONED? Receptor Modeling Chemical Mass Balance (multiple tracers for one time) Regressions over time (one tracer) Spatial techniques (EOF) First Principle (Deterministic Models) Hybrid Techniques

9 Average Current Conditions

10 Trends in Monthly Average Species Conc

11 , Ammonium Sulfate Scattering, 1988 Worst 20 Percent Haze Days

12 SO 2 AND SO 4 COMPARISON 80 th Percentile Sulfate and Annual SO2 emission rates from EPA NET Inventory,

13 Organic Scattering (4*1.4*OC), Worst 20 Percent Haze Days

14 Absorption (10*EC), Worst 20 Percent Haze Days

15 Jarbidge

16 Great Smoky

17 FRACTION OF CARBON ATTRIBUTTED TO FIRE/SOA

18 Acres burned by wildfire in California and OC mass concentrations at selected IMPROVE monitoring locations

19 Simulation Gridded fire occurrence data serve as surrogates for fire emissions IMPROVE data provide known receptor aerosol mass concentrations ATAD back trajectories select fires that impact IMPROVE sites IMPROVE sites Fire grids ATAD Trajectories

20 Wildland fire contribution to IMPROVE OC for 2000

21 Biogenic vs Fossil Carbon Biogenic or fossil carbon content in aerosol ( µg/m 3 ) y = x R= Biogenic carbon mass Fossil carbon mass Total carbon content in aerosol ( µ g/m 3 )

22 MOLECULAR MARKERS ο ο Molecular Markers = Source Tracers Source Apportionment Required Molecular Marker Properties Representative for source (unique) Stable in atmosphere (stable molecular structure) Detectable concentration Analytical accuracy + precision Primarily in the particle phase

23 WOOD PYROLYSIS - SMOKE ο ο Wood Combustion Thermal degradation of wood components (lignin and cellulose) is typically incomplete Wood Combustion Products Alkanes, alkenes, alkanols, alkanals, alkanoic acids Substituted benzenes, PAHs, oxy-pahs Marker compounds

24 Some Organic Source Markers Meat cooking Vehicle exhaust Wood combustion

25 Wood smoke marker concentrations track OC 8 Levoglucosan vs. IMPROVE OC Weekly Averages Levoglucosan (ng/m y = 0.53x R 2 = OC (µg/m3)

26 Secondary biogenic compounds also correlate with OC 30 Pinic Acid vs. IMPROVE OC Weekly Averages Pinic acid (ng/m y = x R 2 = OC (µg/m3)

27 Organic Carbon vs Potassium Organic carbon is highly correlated with water soluble Potassium suggesting smoke

28 BIOGENIC VS FOSSIL PRIMARY VS SECONDARY Biogenic Fossil TOTAL Primary 20% 15% 35% Secondary 60% 5% 65% TOTAL 80% 20% 100%

29 CARB Aerosol Monitoring during a Smoke Event, Oct. 18, 1999 There are over a dozen CARB aerosol sites that are exposed to smoke in the Central Basin on The 3 aerosol monitors show peak smoke concentration in the 200 µg/m 3 range The composition of the smoke varies; some puffs are high in scattering, others high in absorption (COH)

30 NAAPS Simulation of Los Alamos Smoke Plume, May 12, 2001 Smoke detected at DOE/ARM site in Oklahoma May 11 and 12 first attributed to Los Alamos Fires NAAPS shows smoke is a combination of two plumes: Transport of Los Alamos smoke in elevated dry layer Transport of Central American smoke in low-level moist layer NOGAPS RH, winds, θ 5/12 5/11 5/10 5/9

31 SO WHAT IS NEEDED TO ADEQUATELY ASSESS SMOKE CONTRIBUTION TO CARBONACEOUS AEROSOL? RECEOPTOR ORIENTED MODELS DETERMINISTIC MODELS

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33 Acres burned by wildfire in Colorado and OC mass concentrations at selected IMPROVE monitoring

34 Wood smoke Biomass burning is an important source of ambient aerosol Domestic combustion (wood stoves and fireplaces) Fires (prescribed or wild) Examples: Downtown L.A.: 12% of OC (Schauer et al., 1996) Fresno (Jan96): 56% of OC (Schauer and Cass, 2000) Southeastern U.S.: 12±15% of PM2.5 (Zheng et al., 2002) Big Bend NP (summer): <1% of OC (Brown et al., 2002)

35 Issues and problems related to source profiles 1 study only on emission profile for foliage fuels (Hays et al., 2002) limited to foliage fuels very limited set of plant types no data for variation of emissions with burning regime Emission from campfires (Simoneit et al., 2000) only one type of pine wood Emissions by larger fires (Oros and Simoneit, 2001) more realistic conditions (controlled burns) experiments limited to Western US only one sample per fuel type

36 Needed emission profile improvements realistic prescribed/wildfire conditions large scale lab experiments or field tests more representative range of fuels (including foliage) variability of emissions with fire regime e.g., flaming vs. smoldering

37 Marker stability Some studies question the stability of levoglucosan (Brown et al., 2002; Gao et al, 2003) possible degradation during transport? readily undergoes acid hydrolysis to form glucose Stability of methoxyphenols is questioned photochemical degradation? interconversion of one species into another? No data available for resin acids or retene need for stability studies

38 Selected wood smoke markers: methoxyphenols (hardwood vs softwood) OH OH O O O O Vanillin (softwood - pine) HO O Syringaldehyde (hardwood - oak) O 4-ethylguaiacol (both)

39 Sugar anhydrides Wood composition cellulose 45% hemicellulose 30% Levoglucosan Cellulose thermal decomposition product Major component of wood smoke Mannosan and Galactosan Stereoisomers of levoglucosan Formed from hemicellulose decomposition Much less abundant than levoglucosan lignin 25%

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