BIOGENIC VOLATILE ORGANIC

COMPOUNDS

at

AZUSA & ELEVATED SITES:

INDICATION of

NIGHTTIME NO3 RADICAL CHEMISTRY

Janet Arey and Anni Reissell

Air Pollution Research CenterUniversity of California, Riverside

Presented at

SCOS97-NARSTO Data Analysis ConferenceFebruary 13-15, 2001

South Coast Air Quality Management District

Map of South Coast

AZUSA - mid-basin site

PINE MOUNTAIN - 11 km north of Azusa- 1350 m. elevation

MOUNT BALDY - 25 km northeast of Azusa- 1220 m. elevation

Biogenic Volatile Organic Compounds (BVOCs)

emitted from vegetation (isoprene requireslight)

isoprene, -pinene & limonene very reactive

Sampling

Carbotrap solid adsorbent Ozone scrubber

Analysis

Internal standards GC/MS with selected ion monitoring 3-hr daytime samples 3-7 hr nighttime samples

Coastal plain bounded by inland mountains inthe presence of a strong temperature inversion.

From: Lu and Turco (1994) J. Atmos. Sci., Vol.

51, p. 2306.

Pin

e M

t. P

ER

C/A

zusa

PE

RC

0.0

0.2

0.4

0.6

0.8

PDT

Ozo

ne (

ppbv

)

0

20

40

60

80

100

120O3 Azusa

O3 Pine Mtn.

NO

x at A

zusa

(pp

bv)

0

20

40

60

80NO NO2

20 24 04 08 12 16 20 24 04 08 12 16 20 24 04 08

20 24 04 08 12 16 20 24 04 08 12 16 20 24 04 08

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

Sept. 4-7, 1997

NOx and O3

transportedto elevatedsite

Elevated siteisolatedfrom NO

Evening:

At Azusa: O3 + NO NO2 + O2

In Inversion layer: NO2 + O3 NO3 + O2

Calculated Lifetimes of Selected BVOCs

Structure BVOCRxn.

with OHa

Rxn .

Rxn. withNO3

bRxn.

with O3c Photolysis

Isoprene 1.4 hr 49 min 10 hr

MACR 4.9 hr 14 day 5 day ~1 day

MVK 6.9 hr >385 day 1.2 day ~2 day

-Pinene 2.6 hr 5 min 1.5 hr

-Pinene 1.8 hr 13 min 8.8 hr

Limonene 49 min 3 min 40 min

1,8-Cineole 12.5 hr 270 day >37 day

Camphor 2.5 day >150 day >80 day

a For an OH radical concentration of 2.0 x 106 molecules cm-3 (12-hr daytime average).b For an NO3 radical concentration of 5 x 108 molecules cm-3 (12-hr nighttime average).c For an O3 concentration of 2.1 x 1012 molecules cm-3 [90 ppbv] (24-hr average).

O

O

H2C C

CH3

CHO

H2C C CH CH2

CH3

H3C C CH CH2

O

Isop

rene

(pp

bv)

0.0

0.4

0.8

1.2

1.6

2.0

-P

inen

e (p

ptv)

0

5

10

15

20

25

30

Isoprene Pinene

MA

CR

, M

VK

(pp

bv)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

PE

RC

, 10

x C

amph

or (

pptv

)

0

50

100

150

200

250

300MACR MVK Camphor PERC

PDT

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

Pine Mountain - Sept. 4-7, 1997

Ozo

ne (

ppbv

)

0

40

80

120

160

O3 Azusa

O3 Mt. Baldy

NO

2 M

t. B

aldy

(pp

bv)

0

4

8

12 NO2 Mt. Baldy

04 08 12 16 20 24 04 08 12 16 20

PDT

24

Sept. 28-29, 1997

Isop

rene

(pp

bv)

0.0

0.8

1.6

2.4

Mon

oter

pene

s (p

ptv)

0

40

80

120

160

200

MA

CR

, M

VK

(pp

bv)

0.0

0.4

0.8

BV

OC

(pp

tv)

0

10

20MACR MVK Cineole Camphor

Isoprene PineneLimonene

09-1

2

PDT

13-1

6

17-2

0

20-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

Mt. Baldy - Sept. 28-29, 1997

A

Nighttime Model for Mt. BaldyInitialized for Sept. 28, 1997: BVOC (1700-2000 hr), 100 ppbv O3 and 10 ppbv NO2

Time (seconds)

0 2000 4000 6000 8000 10000

Mol

ecul

es c

m-3

1e+10

2e+10

3e+10

4e+10

5e+10

6e+10

7e+10

Isoprene MVK MACR

Time (seconds)

0 2000 4000 6000 8000 10000

Mol

ecul

es c

m-3

1e+9

2e+9

3e+9

4e+9

-Pinene Limonene Cineole Camphor

Possible Sources of BVOCs at Azusa

1. Local emissions

2. Transport

3. Anthropogenic sources

Isoprene, MACR, MVK

1. Local emissions YesEucalyptus trees

2. Transport LikelyDaytime (MACR + MVK)/Isoprene > 2.4

3. Anthropogenic (traffic) Not dominantPoor correlation with CO

ppbv

0.0

0.5

1.0

1.5

2.0

IsopreneMACR MVK

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

PDT

ppbv

0.0

0.4

0.8

1.2

Sept 4-7, 1997

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

Azusa

Pine Mtn

0

2

4

0

2

4

(MACR + MVK)Isoprene

(MACR + MVK)Isoprene

Possible Sources of BVOCs at Azusa

Monoterpenes

1. Local emissions Yes

2. Transport Likely

Early morning maxima

Consistent with build-up overnight from emissionsinto shallow marine layer and/or downslope flowsinto shallow marine layer.

Consistent with lack of chemistry during nighttimeat Azusa. NO titrates O3. No O3, no NO3 radicalformation and no OH radical formation from O3-alkene reactions.

3. Anthropogenic sources YesSept. 28, 1997 0600-0900 hr:[Limonene] = 3.8 ppbv

ppbv

0.0

0.4

0.8

1.2

1.6IsopreneMACR MVK

ppbv

0.0

0.2

0.4

0.6

pptv

0

20

40

PDT

CamphorCineole

PineneSabineneLimonene Pinene

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

09-1

2

13-1

6

17-2

0

20-2

4

00-0

3

03-0

6

06-0

9

Reactive

Nonreactive

Azusa - Sept.4-7, 1997

Relative Reactivities of VOCs at Azusa Aug. 5, 1997 0600-0900 hr

k OH x

[V

OC

] (s-1

)

0

1

2

benz

ene

tolu

ene

isop

rene

MA

CR

M

VK

-p

inen

esa

bine

ne -p

inen

elim

onen

eci

neol

eca

mph

or

CONCLUSIONS

Isoprene was the dominant BVOC at the elevatedsites, and its maximum mixing ratios occurredduring the early afternoon.

Nighttime NO3 radical chemistry occurred at theelevated sites rapidly decreasing isoprene andreactive BVOC concentrations.

Monoterpenes and the isoprene reaction productsmethacrolein and methyl vinyl ketone were thedominant BVOC at Azusa, with the monoterpenemaximum mixing ratios occurring in the earlymorning hours.

The values of the ratio (MACR + MVK)/Isoprene atAzusa suggest that the methacrolein and methylvinyl ketone may have been transported fromelevated sites where the isoprene was depleted byreaction with the NO3 radical.

BVOC at Azusa will contribute to the peroxyradicals (and hence to O3 formation) especially inthe early morning.

ACKNOWLEDGEMENTS

Roger AtkinsonCheryl Harry

Eric ShamanskyPatricia McElroyWilliam D. LongSara AschmannYong Jae Chung

Patricia T. PhousongphouangAlvaro AlvaradoAndrew Chew

PARTICULAR THANKS TO

Rudy Eden (SCAQMD)Bart Croes (CARB)

Randy Pasek (CARB)Ash Lashgari (CARB)Arthur Winer (UCLA)

THANKS FOR FINANCIAL SUPPORT

California Air Resources BoardUniversity of California Campus Laboratory

Collaboration Program (Pacific Rim)Maj and Tor Nessling Foundation