The Role of Nighttime Chemi

The Role of Nighttime Chemi

Winter Ammonium Nitrate For

Winter Ammonium Nitrate For

in the San Joaquin Valle

in the San Joaquin Valle

Michael McCarthy Michael McCarthy

Steve Brown Steve Brown

Fred Lurmann Fred Lurmann

Paul Roberts Paul Roberts

Sonoma Technology, Inc. Sonoma Technology, Inc.

Petaluma, CA Petaluma, CA

AAAR Specialty Conference AAAR Specialty Conference

February 10, 2005 February 10, 2005

Atlanta, GA Atlanta, GA
Objectives Objectives

As part of a larger study examining w

As part of a larger study examining w

PM in the SJV, CRPAQS gas and 

PM in the SJV, CRPAQS gas and 

data were used to address two qu

data were used to address two qu

What precursors limit ammonium nitrate fo

What precursors limit ammonium nitrate fo

NH3 or HNO3? NH3 or HNO3?

Which nitric acid formation pathways are i

Which nitric acid formation pathways are i

Daytime or Nighttime or Both? Daytime or Nighttime or Both?

CRPAQS = California Regional PM10/PM2.
CRPAQS - 5 Core S

CRPAQS - 5 Core S
Average Distribution of Average Distribution of PM2.5 Chemica

PM2.5 Chemica

 at the Five Core CRPAQS Sites i

 at the Five Core CRPAQS Sites i

(15 IOP days in Dec 2000 – Feb 

(15 IOP days in Dec 2000 – Feb 

0

10203040506070

Bethel

Island

Fresno Bakersfield Angio

Concentratoin (ug/m3)

Based on 3-hr to 8-hr samples from DRI’s Seque
15-day Average Phase Distribution of NO 15-day Average Phase Distribution of NO

x-Re

-Re

CRPAQS Winter 2000/2001 IOP D

CRPAQS Winter 2000/2001 IOP D

0

1020304050607080

Bethel Island Fresno Bakersfield Angiola 

Location

Concentration (ugm-N/m3)

HNO

3 data were not available at Bethel Island and B
Reg

Reg

P

P

San 

San 

De

De

C

C
Comparison of Ammonia and N

Comparison of Ammonia and N

-10

0

102030405060

-2 0 2 4 6 8 10 12 14 16 18

HNO3 Concentration (ug-N/m3)

NH3 Concentration (ug-N/m3) 1:1 Line

-4

048

121620

-2 0 

HNO3 Con

NH3 Concentration (ug-N/m3) 

Angiola 

NH3 + HNO3 NH3 + HNO3 

? NH4NO

HNO3 is limiting because HNO3 is limiting because HNO

HNO
Comparison of Ammonia and N

Comparison of Ammonia and N

at a Low Ammonia Sit

at a Low Ammonia Sit

HNO3 is still the limiting sp

HNO3 is still the limiting sp

-1

0123456

-1 0 1 2 3

HNO3 Concentration (ug-N/m3)

NH3 Concentration (ug-N/m3) 1:1 Line
Nitric Acid Formation Pa

Nitric Acid Formation Pa

Daytime Formation: Daytime Formation:

NO2 + OH NO2 + OH 

Æ HNO3

Nighttime Formation: Nighttime Formation:

NO2 + O3 NO2 + O3 

Æ NO3 + O2

NO2 + NO3 + M

Æ N2O5 + M N2O5 + M

N2O5 + H2O N2O5 + H2O 

Æ 2 HNO3

NO3 + R 

Æ HNO3+ organic product

+ organic product

Inhibiting Reactions: Inhibiting Reactions:

NO3 + h

ν

Æ NO + O2 NO + O2 Su

Su

NO3 + h

ν

Æ NO2 + O NO2 + O

NO3 + NO 

Æ 2 NO2 Fr

Fr

NO3 + NO2 

Æ NO + NO2 + O2 NO + NO2 + O2

N2O5 

Æ NO2 + NO3 W

W

NO3 + R 

Æ NO2 or RNO3 NO2 or RNO3 Ce

 Ce
15-day Average PM2.5 Nitr

15-day Average PM2.5 Nitr

Concentrations by Sampling P

Concentrations by Sampling P

05

10152025303540

0-5

5-10

10-13

13-16

16-24

0-5

5-10

10-13

13-16

16-24

0-5

5-10

10-13

13-16

16-24

0-5

5-10

10-13

Bethel Island Fresno Bakersfield Angi

Time Period (PST) and Location

C oncentration (u g /m 3 )
Daytime HNO3 Produ

Daytime HNO3 Produ

• Within the 5 diurnal sampling periods, th

Within the 5 diurnal sampling periods, t

PM2.5 nitrate levels occurred at PM2.5 nitrate levels occurred at

• 1000-1300 PST in Fres 1000-1300 PST in Fresno and Bakersfield no and Bakersfield

• 1300-1600 PST in Angiola, Sierra Nevada F

1300-1600 PST in Angiola, Sierra Nevada F

Bethel Island Bethel Island

• The peaks in ozone concentrations, the 

The peaks in ozone concentrations, the 

of photochemical activity, occur from 12

of photochemical activity, occur from 12

at most SJV sites in winter at most SJV sites in winter

• The diurnal pattern of aerosol nitrate co

The diurnal pattern of aerosol nitrate co

in the SJV suggests the daytime nitric a

in the SJV suggests the daytime nitric a

is occurring in the region is occurring in the region
Fresno

Hourly Concentrations of NO, O3, and 

Hourly Concentrations of NO, O3, and 

Dec 28 Dec 29 Dec 30 

05

10152025303540

0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21 0 3 6 

NO3 (ug/m3) and Ozone (ppb)

NO3 Ozone NO

9 am

9 am

10 am

11 a
Fresno

Hourly Concentrations of NO, O3, and 

Hourly Concentrations of NO, O3, and 

05

1015202530354045

0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21 0 3 6 9 

NO3 (ug/m3) and Ozone (ppb)

NO3 Ozone NO

9 am

9 am

9 am

Feb 1 Feb 2 Fe
Angiola Tower - 90 m above gro

Angiola Tower - 90 m above gro

Hourly concentrations of NO, O3, and P

Hourly concentrations of NO, O3, and P

05

10152025

12

15

18

21

0

3

6

9

12

15

18

21

0

3

6

9

12

15

18

21

0

3

6

9

12

15

12/27/2000 12/28/2000 12/29/2000 12/30/200

Time (PST) and Date

NO3 Concentration (ug/m3) 

NO3 Ozone NO

Night

Night 

Night
Angiola Tower - 90 m above g

Angiola Tower - 90 m above g

Hourly concentrations of NO, O3, and 

Hourly concentrations of NO, O3, and 

05

10152025

12

15

18

21

0

3

6

9

12

15

18

21

0

3

6

9

12

15

18

21

0

3

6

9

12

15

1/31/2001 2/1/2001 2/2/2001 2/3/2001 

Time (PST) and Date

NO3 Concentration (ug/m3) 

NO3 Ozone NO

Night Night Night
Angiola Tower NO and Ozone – 

Angiola Tower NO and Ozone – 

-1

0 1 2 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

HOUR

0

1020304050607080

7m NO ppb

-1

0 1 2 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

HOUR

0

1020304050607080

7m NO ppb

-1

0 1 2 3 4 5 6 7 

0

10203040506070

90m O3 ppb

-1

0 1 2 3 4 5 6 7 

0

10203040506070

90m O3 ppb

-1

0 1 2 3 4 5 6 7 8 

0

10203040506070

7m O3 ppb

-1

0 1 2 3 4 5 6 7 8 

0

10203040506070

7m O3 ppb

-1

0 1 2 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

HOUR

05

10152025303540

90m NO ppb

-1

0 1 2 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

HOUR

05

10152025303540

90m NO ppb

Ozone 

NO Aloft (90m) Ozone NO Surface (7m)

NO islowaloft atnight
Angiola Tower Angiola Tower NOy and PM2

 and PM2

-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

HOUR

0

102030405060708090

9

0

m

N

O

y

p

p

b

-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

HOUR

0

102030405060708090

9

0

m

N

O

y

p

p

b

-1 0 1 2 3 4 5 

05

101520253035

9

0

m

N

O

3

u

g

m

/

3

-1 0 1 2 3 4 5 

05

101520253035

9

0

m

N

O

3

u

g

m

/

3

-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

HOUR

0

102030405060708090

7

m

N

O

y

p

p

b

-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

HOUR

0

102030405060708090

7

m

N

O

y

p

p

b

PM2.5 

NOy Aloft (90m) PM2.5 NOy Surface (7m)

-1 0 1 2 3 4 5 

05

101520253035

7

m

N

O

3

u

g

/

m

3

-1 0 1 2 3 4 5 

05

101520253035

7

m

N

O

3

u

g

/

m

3

NOy isplentifulaloft atnight
Rate Limiting Facto

Rate Limiting Facto

• NOx is abundant in SJV in win

NOx is abundant in SJV in win

• Daytime HNO3 production rat

Daytime HNO3 production rat

limited by sunlight, VOCs, and limited by sunlight, VOCs, andbackground ozone background ozone

• Nighttime HNO3 production is 

Nighttime HNO3 production is 

background ozone which is ab

background ozone which is ab

aloft but not at the surface aloft but not at the surface
Conclusions Conclusions

• Particulate NO Particulate NO3 concentrations are small 

 concentrations are small 

gaseous NO gaseous NOy precursor concentrations precursor concentrations

• Ammonium nitrate concentrations Ammonium nitrate concentrations are lim

 are lim

HNO3 formation, rather than by formation, rather than by the availa

 the availa

• HNO3 is formed via both daytime photoch

 is formed via both daytime photoch

nighttime chemistry nighttime chemistry

• Nighttime chemistry aloft may significantly 

Nighttime chemistry aloft may significantly 

regional nature of ammonium ni regional nature of ammonium nitrate in w

trate in w
Acknowledgemen

Acknowledgemen

• Sponsored by San Joaquin Va

Sponsored by San Joaquin V

Pollution Study Agency Pollution Study Agency

• Managed by California Air Re

Managed by California Air Re

Board staff Board staff
The End The End
PM2.5 nitrate concentrations in PM2.5 nitrate concentrations in Fresno and Ba

 Fresno and Ba

January 31 to February 3, 2001 January 31 to February 3, 2001

0

1020304050

0-5 5-10 10-1313-1616-24 0-5 5-10 10-1313-1616-24 0-5 5-10 10-1313-1616

1/31/2001 2/1/2001 2/2/2001 

Sampling Period (PST) and Date

Concentration (ug/m3) Fresno Bakersfield
PM2.5 nitrate concentrations in PM2.5 nitrate concentrations in Sierra Nevada 

 Sierra Nevada 

Angiola from January 31 to February 3

Angiola from January 31 to February 3

0

1020304050

0-5 5-10 10-1313-1616-24 0-5 5-10 10-1313-1616-24 0-5 5-10 10-1313-161

1/31/2001 2/1/2001 2/2/2001 

Sampling Period (PST) and Date

Concentration (ug/m3) Sierra Nevada Foothills Angiola