Fine Aerosol Composition - Atmospheric Chemistry - Lecture Slides, Slides of Chemistry

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FINE AEROSOL COMPOSITION IN NORTH AMERICA^ Annual mean PM

concentrations (NARSTO, 2004)2.^ Current air quality standard is 15

-3 g m

SULFATE-NITRATE-AMMONIUM AEROSOLS IN U.S.

Highest concentrationsin industrial Midwest(coal-fired power plants)

Sulfate^

Nitrate

Ammonium

Acidity

Distributions of HNO

(g) and NO 3

-^ (aerosol) in surface air 3

HNO(g)^3

-^ NO(aerosol) 3 EPA network data for 2006

Zhang et al. [2012]

FORMATION OF SULFATE-NITRATE-AMMONIUM AEROSOLS

(^222)

2 2 4

4 3

4 3

3 3

3

4 3

(^ )^

(^ ) (^ ) (^ )^

(^ )^

(^

^     

 ^ 

^

H O

H O H O

H SO^

g^

SO^

H

NH^ g^

NH^

OH

HNO^

g^

NO^ H

NH^ g^

HNO^

g^ NH NO

Sulfate always forms an aqueous aerosolAmmonia dissolves in the sulfate aerosoltotally or until titration of acidity, whicheverhappens firstNitrate is taken up by aerosol if (and only if)excess NH aerosol

is available after sulfate 3 titration

HNOand excess NH^3

3 can also form a solid aerosolif RH is low Thermodynamic rules: Highest concentrationsin industrial Midwest(coal-fired power plants) Condition

aerosol pH

Low RH

High RH

2[S(VI)] > [N(-III)]

acid

HSO•nH^24

O, 2

NH^ HSO^4

(NH^ 4 , 4

)^ SO^24

+^ (NH , H 4

+^ 2-^ , SO)^4

solution

2[S(VI)]^ ≤

[N(-III)]^

neutral^

(NH^ )^ SO^4

NH^ NO^4

+^ (NH , SO 4

2-^ -^ , NO 43

solution

docsity.com

Observation of SO

point sources in US by OMI oversampling 2

SO2 point sources, 2004-

OMI SO^2

(3 km oversampling) 3 km-resolution data enablesanalysis of SO

emission trends, 2 SOatmospheric lifetime^2

AQAST PI: De Foy

SOcolumns observed from SCIAMACHY^2

Andreas.Richter@iup.physik.uni-bremen.deAndreas.Richter@iup.physik.uni-bremen.de

Kasatochi eruption as seen in GOME-2 SO

2

-^ After some smaller SO

2

emissions,large eruption on August 8, 2008 • SOrapidly distributes over the^2 NH • GOME-2 integrated SO

column 2

indicates more than 1 Tg totalSOemission^2

http://www.avo.alaska.edu/

Kasatochi volcanoAltitude: 314 mLatitude: 52.

°N Longitude: 175.

°^ W

OBSERVED TITRATION OF SO

BY H 2

OIN CLOUD 22

First aircraft observations by Daum et al. [1984]

WORLDWIDE MEASUREMENTS OF FINE AEROSOL COMPOSITION

CARBONACEOUS AEROSOL SOURCES IN THE U.S.

Fossil fuelBiofuelBiomass burningVegetation

ORGANIC CARBON (OC)

2.7 Tg yr

BLACK CARBON (BC)0.66 Tg yr

-1 Annual mean concentrations (2001)

BC^

OC

Park et al. [2006]

RADIATIVE FORCINGFROM BLACKCARBON (BC)

IPCC [2007]docsity.com

BC is emitted by incomplete combustion

“BC” or “soot” is optically defined and includes both graphitic elementalcarbon (EC) and light-absorbing heavy organic matterDiesel engines are large BC sources

Freshly emitted BC particle

BC and OC aerosol during ARCTASaircraft campaign (spring 2008)

Wang et al. [2011]

ORGANIC AEROSOL IN STANDARD GEOS-Chem MODEL

fuel/industry

open fires

OH, O,NO^3

3 SOG

SOA

POA

K

vegetation

fuel/industry

open fires

isopreneterpenesoxygenates…^700

alkenesaromaticsoxygenates…^30

alkanesalkenesaromatics… VOC EMISSION

PRIMARY EMISSION

VOC^50

Global sources in Tg C y

-1 secondaryformation

SOA^ ≡^ secondary organic aerosolPOA^ ≡^ primary organic aerosol