7/10/13  

1  

Types  of  Aerosols  

What is an Aerosol?

•  Suspension of liquid or solid particles in a vapor phase

•  Colloidal suspension that may be stable for <1 s or > 1 yr

1.1

Particle + Vapor = AEROSOL

Major sources of particles •  combustion •  incineration •  road dust •  power plants •  automobiles •  sea salt •  biogenic Wildfires and

forests

Fossil fuels

Marine

Terrestrial  Biogenic  and  Biomass  Burning  (Alkenes)  

Fossil  Fuels  (Alkanes)   Primary  Marine  Carbohydrates  

7/10/13  

2  

Black Carbon •  Climate forcing agent •  Formed through the incomplete combustion of

fossil fuels, biofuel, and biomass •  Consists of pure carbon in linked forms •  It warms the Earth by absorbing heat in the

atmosphere and reducing the albedo, or ability to reflect sunlight

•  Stays in the atmosphere for several days to weeks

Canonical View of Secondary Organic Aerosol (SOA)

Haagen-Smit, 1952

But this was a simplification; we know there are different types of hydrocarbons

(emitted from different sources) that make different types of SOA:

ergo not all SOA is alike.

“H”+”C”

+”O”

Carbon Reservoir

CO

2

Volatile Organic Carbon (Vapors)

Formation Process

Primary Particles

Secondary Particles

Source Type

Foss

il

Hyd

roca

rbon

s (G

asol

ine,

Die

sel)

Terr

estri

al

Vege

tatio

n M

arin

e O

rgan

ism

s

FFC

Fo

ssil

Fuel

C

ombu

stio

n

BB

B

Bio

fuel

and

B

iom

ass

Bur

ning

BVF

B

ioge

nic

Vapo

r Fl

ux

MB

C

Mec

h.-lo

fted

Bio

Com

pone

nts

C12-C25 Alkanes, <C15 Aromatics

Photochemical Oxidation

Evaporation and Combustion

Evaporation and Combustion

Ether, Ketone, and Acid OFG

Cellulose >C15 Aromatics Black Carbon

Hydroxy-Phenols, Alkenes

Photochemical Oxidation

Metabolism and Combustion

Combustion

Hydroxyl, Ketone, and Acid

OFG

Cellulose, Detritus

(Hydroxyl OFG)

Alkenes (Several Terpenoids)

Photochemical Oxidation

Metabolism

Wind-blown Lofting

Acid OFG (MSA)

Carbohydrates, Saccharides

(Hydroxyl OFG)

Alkenes (Isoprene), Glyoxal, DMS Photochemical

Oxidation Metabolism

Wave-breaking and Bubble Bursting

Alkane, Hydroxyl, and

Acid OFG >C25 Alkanes

>C15 Aromatics Black Carbon

Contributions of Organic Sources

Russell et al., 2011

Biogenic POA+SOA Biomass Burning

Alkane POA+SOA More Oxidized SOA

Marine POA SOA+Marine POA

Spectra for POA+SOA

from Different Sources

Sulfate  Aerosol  ParFcles  

•  Sulfur  in  coal  and  oil  becomes  SO2  gas  when  burned,  then  oxidizes  to  SO4

2-­‐    

•  SO42-­‐  coagulates  into  sulfate  parFcles  

•  ParFcles  are  hygroscopic  (aNract  water)  •  ParFcles  scaNer  nearly  all  solar  radiaFon  •  ParFcles  rain  out  within  a  couple  weeks  (and  produce  acid  rain)