To what extent can biogenic soa be controlled
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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?

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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


To what extent can biogenic soa be controlled

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


To what extent can biogenic soa be controlled

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


To what extent can biogenic soa be controlled

Percent of emitted species from controllable and uncontrollable sources

controllable sources – gray

uncontrollable sources - white

Carlton et al., ES&T (2010)


To what extent can biogenic soa be controlled

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


To what extent can biogenic soa be controlled

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


To what extent can biogenic soa be controlled

Change in population-weighted AQ metrics


To what extent can biogenic soa be controlled

Cloud SOA

2003 Monthly-Averaged CMAQ Results at RTP


To what extent can biogenic soa be controlled

Cloud SOA Precursors

glyoxal

methylglyoxal

2003 Monthly-Averaged CMAQ Results at RTP


To what extent can biogenic soa be controlled

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


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