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To What Extent Can Biogenic SOA be Controlled?

To What Extent Can Biogenic SOA be Controlled?. Annmarie Carlton, Rob Pinder, Prakash Bhave, George Pouliot CMAS – Chapel HIll, NC. Important Findings. CMAQ Simulations indicate anthropogenic pollution enhances predicted biogenic SOA concentrations in the U.S. substantially ~ 50%

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To What Extent Can Biogenic SOA be Controlled?

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  1. To What Extent Can Biogenic SOA be Controlled? Annmarie Carlton, Rob Pinder, Prakash Bhave, George Pouliot CMAS – Chapel HIll, NC

  2. Important Findings CMAQ Simulations indicate anthropogenic pollution enhances predicted biogenic SOA concentrations in the U.S. substantially ~ 50% • Effects are largest in eastern U.S. • POC and NOx are largest individual pollutant classes contributing to overall biogenic SOA

  3. MOTIVATION Non-fossil (biogenic) carbon is a dominant component of atmospheric organic aerosol Substantial portion of PM2.5 carbon is ‘modern’ even in urban areas(Lewis et al., 2004; Szidat et al., 2006; Bench et al., 2007; Gelencsér, et al., 2007) Tracer-based ambient SOA ‘measurements’ dominated by contributions from biogenic hydrocarbons(Edney et al., 2003; Kleindienst et al., 2007) Ambient WSOC, AMS OOA spectra and other indicators of SOA correlate strongly with tracers of anthropogenic pollution(Weber et al., 2007; de Gouw et al., 2005; Goldstein et al., 2009) If anthropogenic pollution is enhancing biogenic SOA how can this contribution be quantified?

  4. SOAA POA POA SOAB SOAA SOAB Anthropogenic/Biogenic Interactions in SOA Formation SVOC SVOC SVOC SVOC anthropogenic VOCs biogenic VOCs oxidants oxidants controllable emissions (e.g., anthropogenic VOCs) non-controllable (e.g., biogenic VOCs) H+ effects not shown

  5. Estimating Anthropogenic Contribution to “Biogenic” SOA • Difficult to directly measure in the atmosphere • O3, OH ambient measurements – no insight as to whether the precursor was anthropogenic or biogenic • PM mass - can make estimates only about organic precursors with detailed chemical analysis • Can investigate large scale trends and relationships with an atmospheric model (CMAQ) by manipulating emissions

  6. accumulation mode organic PM cloud water monoterpene ∙OH,O3 AORGC ATRP1, ATRP2 SV_TRP1 SV_TRP2 O3P, NO3 ∙OH dissolution AOLGB sesquiterpenes ASQT ∙OH,O3, or NO3 glyoxal methylglyoxal POA SV_SQT AISO1, AISO2 AISO3 H+ ∙OH isoprene SV_ISO1, SV_ISO2 VOCs O3,O3P, or NO3 EMISSIONS Pathways do not contribute to SOA EMISSIONS EMISSIONS EMISSIONS Non-volatile

  7. Modeling experiment • Simulation of August 15 - September 4, 2003 • Continental US • Time period has high biogenic contribution to SOA • Emissions: controllable versus not controllable Not Controllable Controllable Everything else: Power plants Vehicles Agricultural burning Area sources Wildfire Prescribed burning VOCs from plants / trees Soil NOx Lightning NOx

  8. Percent of emitted species from controllable and uncontrollable sources controllable sources – gray uncontrollable sources - white Carlton et al., ES&T (2010)

  9. Biogenic SOA at the Surface (<~34 m): 18 day average Base CMAQ simulation all emissions Fraction of biogenic SOA from controllable pollution non-controllable emissions = biogenic emissions + wildfires + prescribed burns fraction Carlton et al., ES&T (2010) Results averaged from Aug. 18th – Sep. 4th, 2003

  10. Difference in predicted biogenic SOA mass concentrations Maxima for time period Average for time period On Average ~ 1 ug/m3 of Biogenic SOA in SE is from controllable sources • Additional simulations to estimate effects and contributions of individual species • POC, NOx, VOC, SO2, NH3

  11. To control biogenic SOA – what should regulators focus on? • What emitted species are most important? • What locations are most impacted? • Group the anthropogenic emissions into • VOC: Volatile Organic Carbon • POC: Primary Organic Carbon Particles • NOx • Remove one of these species at a time • Calculate change in biogenic SOA

  12. Regional Influence of Controllable Emissions on “Biogenic” SOA Controllable POC Controllable NOx Controllable SO2 Surface (<~34 m) Concentration; 18 day average

  13. Change in population-weighted AQ metrics

  14. Cloud SOA 2003 Monthly-Averaged CMAQ Results at RTP

  15. Cloud SOA Precursors glyoxal methylglyoxal 2003 Monthly-Averaged CMAQ Results at RTP

  16. Cloud SOA Precursors ∙OH SOA formation is photochemistry

  17. Conclusions • Used CMAQ to estimate fraction of biogenic SOA that is controllable. • In the Eastern US, ~50% of the biogenic SOA can be controlled by reducing anthropogenic emissions • To reduce concentrations of biogenic SOA, focus on • primary organic carbonaceous particles (POC) and NOx • SO2 impacts biogenic SOA in the southeastern US • Cloud-produced SOA exhibits seasonal cycle similar to ∙OH and biogenic VOCs

  18. Acknowledgements • Sergey Napelenok • Marc Houyoux • Alice Gilliland • Rohit Mathur • Golam Sarwar • Ed Edney, Tad Kleindist, John Offenburg, Michael Lewandowski • Charles Chang & Ryan Cleary

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