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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

To What Extent Can Biogenic SOA be Controlled?

Annmarie Carlton, Rob Pinder, Prakash Bhave, George Pouliot

CMAS – Chapel HIll, NC

important findings
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
slide3

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?

anthropogenic biogenic interactions in soa formation

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

estimating anthropogenic contribution to biogenic soa
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
slide6

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

modeling experiment
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

slide8

Percent of emitted species from controllable and uncontrollable sources

controllable sources – gray

uncontrollable sources - white

Carlton et al., ES&T (2010)

slide9

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

slide10

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
to control biogenic soa what should regulators focus on
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
regional influence of controllable emissions on biogenic soa
Regional Influence of Controllable Emissions on “Biogenic” SOA

Controllable POC

Controllable NOx

Controllable SO2

Surface (<~34 m) Concentration; 18 day average

slide14

Cloud SOA

2003 Monthly-Averaged CMAQ Results at RTP

slide15

Cloud SOA Precursors

glyoxal

methylglyoxal

2003 Monthly-Averaged CMAQ Results at RTP

slide16

Cloud SOA Precursors

∙OH

SOA formation is photochemistry

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