Brought to you by:
Doug Collins
SIO 209
October 20, 2009

(Particulate Matter)
Direct
from
source:
Combus0on
Volcanic
Soil/Dust
Sea
Salt
Aerosol
From
reac0ons
or
“processing”:
Nitrate
forma0on
(from
HNO
3
)
Oxida0on
of
vola0le
organics
[VOC]
Sulfate
forma0on
(from
SO
2
)
Reac0ons
with
NH
3
PM
2.5
PM
10
:

≤
2.5
microns
:
≤
10
microns

•   Elemental Carbon (EC, Soot, Black Carbon)
–   Primary Aerosol: combustion, small particles
•
•   Nitrate (NO
3
)
–   Secondary Aerosol: from HNO
3
NO x
(NO+NO
2
)
–   Gaseous Tracer: combustion, forms HNO photochemically, involved in forming O
3
3
and OH
•   Ozone (O
3
)
–   Gaseous Pollutant: forms photo-chemically from NO
–   Oxidizes VOCs and forms OH x
•   Volatile Organic Compounds (VOC)
–   Biogenic (BVOC): Emissions from trees (pine/citrus scent)
–   From incomplete combustion (motor vehicles)
•   Ammonia (NH
3
)
–   Agriculture: fertilizer, bovine activity

NO
+O
3
or
+RO
2
 hν
NO
2
NO
2
+OH
+RO
2
HNO
3
NO
2
 (at
nigh t)
NO
2
+
O
3
‐‐>
 NO
3

+NH
3
&
H
2
0
+NO
2
 N
2
NH
4
+
(aq)
+
 NO
3
‐
(aq)
O
5
O
+
O
2
‐‐>
 O
3
At
night…
(Pun
and
Signeur,
1999)
 (TH
Bertram,
UCSD)

Winter
PM
2.5
Fall
PM
10
Major
urban
contribu0on
 from
organic
aerosol
(Pun
and
Signeur,
1999)

(Pun
and
Signeur,
1999)

San
Joaquin
Valley
at
night
Conceptual
Model:
1700
PST
–
0900
PST
NH
3(g)
+HNO
3(g)
‐‐>
NH
Secondary
Aerosols
4
+
(aq)
+NO
3
‐
(aq)
Yesterday’s
Pollu0on
 Wind:
1‐6
m/s
Primary
Aerosol,
O
3
NO x
,
VOC
,
NH ,
BVOC
Wind:
(calm)
Temperature
Profile
NO
3
‐ 
produc0on
limited
by
[HNO
3
]
Secondary
Organic
Aerosol
limited
by
reac0on
rates
(not
VOC
supply)
(Lurrmann,
et
al.
2006)

San
Joaquin
Valley
day0me
Conceptual
Model:
0900
PST
–
1300
PST
SUN
Primary
Aerosol,
O
3
,
NO x
,
VOC
 NH
3
,
BVOC
NO
3
‐ ,
organic
aerosol,
 imported
PM
(desert/ocean)
Wind:
1‐3
m/s
Temperature
Profile
Enhanced
photochemistry
(O
3
,
NO x
,
SOA
produc0on)
Mixing
new
pollu0on
with
inherited
PM
and
pollutants
‐‐
new
reactants!
(Watson
and
Chow,
2002)

•   PM
2.5
–   Avg for 12/99 thru 2/00: 44.5 ug/m 3
•   Averages from CLO, FRES, and FSF agree nicely
Source:
US
EPA

Storm
Precipita0on
<1
mm
Precipita0on
(Trace)
US
EPA
24‐hr
Standard
35
μg/m 3
H

DayMme
January
6,
2000
(Sunday)

DayMme
January
9,
2000
(Sunday)

Nocturnal
 Valley‐Wide

Rural
regions
dominated
by
secondary
species
(Chow et al, 2008)
Urban
regions
dominated
by
primary
emissions

•   Temperature inversion layers act as
“containters” for chemical species in SJV
–   Impact on [nocturnal] air quality and regional secondary aerosol formation
•   Secondary particulate nitrate (NO dominates PM
2.5
in winter
3
)
•   Regional Air quality affected by strong concentration of urban emissions overnight
--> released to valley-wide inversion each morning

Chow, J.C. et al, Size-resolved aerosol chemical concentrations at rural and urban sites in Central California, USA, Atmos. Res.
, 90,
243-252, 2008.
Pun, B.K. and C. Signeur, Understanding particulate matter formation in the California San Joaquin Valley: conceptual model and data needs, Atmos. Environ. 33, 4865-4875, 1999.
Watson, J.G. and J.C. Chow, A wintertime PM2.5 Episode at the
Fresno, CA, supersite, Atmos. Environ. 36, 465-475, 2002.
Useful General Reference Text:
Seinfeld, J.H. and S.N. Pandis, Atmospheric Chemistry and Physics:
From Air Pollution to Climate Change, 2 nd Ed. Hoboken, NJ: John
Wiley & Sons, 2006.