Data Meeting:Data Meeting:May 29May 29--31, 200731, 2007

Austin, TexasAustin, Texas

Volatile Organic Compounds (VOCs)Volatile Organic Compounds (VOCs)Measured Aboard the Measured Aboard the Ronald H. BrownRonald H. Brown

1.Overview of instruments and VOCs reported2. •OH loss chemistry and total air mass •OH reactivity3.VOC contribution to •OH loss during TexAQS 2006

GC-FID/MS: J.B. Gilman, W.C. Kuster, and P.D. Goldan(GC)-PIT-MS: D. Welsh-Bon, C. Warneke, and J.A. de Gouw

QCL-TILDAS: S.C. Herndon and M.S. Zahniser (Aerodyne)Other Data: H. Osthoff, B.M. Lerner, and E.J. Williams

1. VOC Instruments on RHB

GCGC--FID; GCFID; GC--MSMS– 5 min sample acquisition– 30 minute sample cycle– Full speciation of VOCs– Lowest detection limit

(~1 ppt)– 80 compounds reported

(GC)(GC)--PITPIT--MSMS– Continuous sampling– 10 second duty cycle– VOCs are not fully resolved– Detection limits (~1 ppb)– 15 masses reported

IdentificationIdentification

Ionization

Mass Filter

SeparationSeparation

QCLQCL--TILDASTILDAS– Spectroscopic technique– Continuous sampling– <1 second duty cycle– Formaldehyde (HCHO)

LOD ~75 ppt– 4 compounds reported

1. Overview of VOCs ReportedAlkanes:C2-C10 linear, branched,

and cyclic

Oxy: Aldehydes, Alcohols, Ketones, etc.

Others: Organic Nitrates, Halocarbons, DMS, Acetonitrile

Aromatics: C6-C9

Alkenes:Ethene, Propene,C4-C6 linear & branched-- Used in plastics production

Terpenes and Ox. Prod:Isoprene -- Used in rubber productiona-Pinene, β-Pinene, Limonene MethacroleinMethylvinylketone

Oxidation Products of Isoprene

Other Alkenes/Monomers:1,3-Butadiene, 1-OcteneStyrene, Acrylonitrile, Vinyl Acetate, Methyl AcrylateMethyl Methacrylate

Mixing ratios and OH loss rates for all compounds Mixing ratios and OH loss rates for all compounds from 2000 and 2006 appear on Gilman et al. poster from 2000 and 2006 appear on Gilman et al. poster

1. Overview of GC-FID/MS Data

1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00Retention Time

Sign

al

GCGC--FIDFID

GCGC--MSMS

Trim

ethy

lben

zene

_123

Lim

onen

ese

c_B

utyl

benz

ene

Trim

ethy

lben

zene

_124

Ben

zene

_1E

thyl

_2M

ethy

ln_

Dec

ane

Trim

ethy

lben

zene

_135

b_P

inen

eB

enze

ne_1

Eth

yl_3

Met

hyl

n_P

ropy

lben

zene

n_P

enty

lnitr

ate

Cam

phen

e

i_P

ropy

lben

zene

a_P

inen

en_

Hep

tana

lTr

icyc

lene

Sty

rene

o_X

ylen

e

Non

ane

Cyc

lohe

xane

_1E

thyl

_4M

ethy

lE

thyl

Met

hylC

yclo

hexa

nem

p_X

ylen

esE

thyl

benz

ene

Chl

orob

enze

neM

ethy

loct

ane_

3n_

But

ylni

trate

Dib

rom

oeth

ane_

12Tr

imet

hylc

yclo

hexa

ne_1

13D

imet

hylc

yclo

hexa

ne_c

_12

Eth

ylcy

cloh

exan

en_

Hex

anal

Dib

rom

ochl

orom

etha

netw

oHex

anon

eth

reeH

exan

one

Tetra

chlo

roet

hyle

neTr

ichl

oroe

than

e_11

2D

imet

hylc

yclo

hexa

ne_1

4D

imet

hylc

yclo

hexa

ne_t

_12

n_O

ctan

eon

e_O

cten

e

Dim

ethy

lcyc

lohe

xane

_t_1

3C

yclo

hexe

ne_1

Met

hyl

Met

hylh

epta

ne_3

Met

hylh

epta

ne_2

n_P

ropy

lnitr

ate

Trim

ethy

lpen

tane

_233

Trim

ethy

lpen

tane

_234

Chl

oro_

Ace

tone

Eth

ylcy

clop

enta

neth

reeP

enta

none

n_P

enta

nal

twoP

enta

none

Met

hylc

yclo

hexa

neth

reeH

exan

one_

25D

imet

hyl

i_P

ropy

lnitr

ate

oneB

utan

oltw

oPen

tene

_23D

imet

hyl

Tric

hlor

oeth

ylen

e

n_H

epta

neon

eHep

tene

Dim

ethy

lcyc

lope

ntan

e_c_

13D

imet

hylc

yclo

pent

ane_

t_13

Trim

ethy

lpen

tane

_224

Dim

ethy

lhex

ane_

22B

enze

neM

ethy

lhex

ane_

3C

Cl4

Dim

ethy

lpen

tane

_23

Eth

ylni

trate

Tric

hlor

oeth

ane_

111

Met

hylc

yclo

pent

ene_

1D

imet

hylp

enta

ne_3

3C

HC

l3tw

oBut

anol

Eth

ylac

etat

eM

ethy

leth

ylke

tone

t_13

_Hex

adie

nen_

But

anal

Trim

ethy

lbut

ane_

223

c_2_

Hex

ene

n_P

ropa

nol

Vin

ylac

etat

etwoP

ente

ne_2

Met

hyl

t_2_

Hex

ene

Met

hacr

olei

ntw

oMet

hylp

ropa

nal

oneH

exen

eM

ethy

lnitr

ate

twoP

ropa

nol_

2Met

hyl

Met

hyla

ceta

teA

ceto

nitri

lei_

Pro

pano

lD

imet

hyls

ulfid

eD

imet

hylb

utan

e_22

CFC

l2_C

F2C

lP

ropa

nal

c_2_

Pen

tene

Isop

rene

oneP

ente

neC

FCl3

i_P

enta

neon

eBut

ene_

3Met

hyl

Met

hano

lc_

2_B

uten

eA

ceta

ldeh

yde

ETH

AN

EE

THYL

EN

E PR

OP

AN

E

CYC

LOP

RO

PA

NE

AC

ETY

LEN

E i_B

UTA

NE

n_B

UTA

NE

CH

3CL t_2_

BU

TEN

EO

NE

_BU

TEN

EM

_PR

OP

EN

Ec_

2_B

UTE

NE

DIM

ETH

YLP

RO

PA

NE

_22

i_P

EN

TAN

En_

PE

NTA

NE

BU

TAD

IEN

E_1

3

• 200+ compounds monitored• Few unknown compounds• 80 compounds reported

>85>85--95% of VOC reactivity by C95% of VOC reactivity by C22--CC1010hydrocarbons measured by GChydrocarbons measured by GC--FID/MSFID/MS

R/V Brown Cruise Track for R/V Brown Cruise Track for TexAQSTexAQS 20062006

Houston, TXHouston, TX

GalvestonBay

Galveston Bay and Houston, TX LocationsGalveston Bay and Houston, TX Locations

Galveston, TXGalveston, TXBarbour’s Cut

Turning Basin Jacinto Point

Houston Ship ChannelHouston Ship Channel

•OH Loss chemistry can lead to ozone formation– OH reaction with VOCs, CO, CH4 initiates

radical chain reaction– Net result is formation of ozone and regeneration of •OH– OH + VOC reaction products (i.e. HCHO) are

also reactive with •OH– Cycle is terminated when •OH + NO2 HNO3

2. •OH Loss Chemistry

•OH + VOCs, CO, CH4hν, NOx (=NO+NO2)

][)( ,11 VOCks VOCOHOH ×=−−τ ““OH loss frequencyOH loss frequency””

O3

Calculation of •OH Loss Rate

2. Total Air Mass •OH Reactivity

Time (UTC)

Tota

l OH

Los

s R

ate

(s-1

)

Ship plumes

Eastern Coast and Gulf CrossingEastern Coast and Gulf Crossing

CH4 (Global Mean)

COVOCsNO2

2. Total Air Mass •OH Reactivity

Time (UTC)

-1

Galveston Bay and HoustonGalveston Bay and Houston

HSCHSC

BarbourBarbour’’s s CutCut

CH4 (Global Mean)

COVOCsNO2

BarbourBarbour’’s Cuts Cut

Tota

l OH

Los

s R

ate

(s-1

)

GulfGulf

2. Mean Air Mass •OH ReactivityAll All GalvGalv. Bay and Houston. Bay and HoustonEast Coast & Gulf CrossingEast Coast & Gulf Crossing

CH4

9 %26 %

26 %39 %

VOCs

CO

NO2

19 %73 %

2%

6 %

NO2

VOCs

CH4

CO

Total Air Mass •OH Reactivity:Mean: 1.0 s-1

Median: 1.0 s-1

Maximum: 2.4 s-1

Minimum: 0.7 s-1

Number of Points: 130

19 %73 %

2%

6 %

NO2

VOCs

CH4

CO

All All GalvGalv. Bay and Houston. Bay and HoustonEast Coast & Gulf CrossingEast Coast & Gulf Crossing

CH4

9 %26 %

26 %39 %

VOCs

CO

NO2

2. Mean Air Mass •OH Reactivity

Total Air Mass •OH Reactivity:Mean: 12.3 s-1

Median: 6.3 s-1

Maximum: 207 s-1

Minimum: 0.8 s-1

Number of Points: 435

3. VOC Reactivity by LocationTotal VOC Total VOC ••OH Loss Rate (sOH Loss Rate (s--11))

Size and color of marker is proportional to Size and color of marker is proportional to Log (OH loss rate with all VOCs)Log (OH loss rate with all VOCs)

Yellow > 12 s-1

Markers > 1 s-1

3. VOC Reactivity by Location

Marine: Marine: 0.29 s0.29 s--11

7/27 17:00 to 8/1 20:00 UTC

HCHOCH3CHO

Mix

Mean Mean ••OH loss OH loss by VOC Groups:by VOC Groups:

Oxygenates

AlkanesAlkenes

Aromatics

Terpenes & Prod.Other Alkenes/Monomers

Other (N, S, Cl, F)

Beaumont: Beaumont: 3.65 s3.65 s--11

8/9 21:00 to 8/10 04:30 UTC

Fresh Mix ofBiogenics

BarbourBarbour’’s: s: 7.0 s7.0 s--11

8/13 01:00 to 8/15 06:00 UTC

VA, ACN1-Octene

C2-C4

Jacinto P.: Jacinto P.: 49.6 s49.6 s--11

9/6 21:00 to 9/7 14:00 UTC

EthenePropene

Pentanes

11stst OO3 3 Event: Event: 4.2 s4.2 s--11

8/17 17:00 to 8/18 00:30 UTC

8 hrDay Avg.

90 ppbOzone

3. VOC Reactivity by LocationBeaumont: Beaumont: 3.65 s3.65 s--11

8/9 21:00 to 8/10 04:30 UTC

Fresh Mix ofBiogenics

Jacinto P.: Jacinto P.: 49.6 s49.6 s--11

9/6 21:00 to 9/7 14:00 UTC

EthenePropene

Pentanes

Marine: Marine: 0.29 s0.29 s--11

7/27 17:00 to 8/1 20:00 UTC

HCHOCH3CHO

Mix

BarbourBarbour’’s: s: 7.0 s7.0 s--11

8/13 01:00 to 8/15 06:00 UTC

Mean Mean ••OH loss OH loss by VOC Groups:by VOC Groups:

Oxygenates

AlkanesAlkenes

Aromatics

Terpenes & Prod.Other Alkenes/Monomers

Other (N, S, Cl, F)

VA, ACN1-Octene

C2-C4HCHO

CH3CHO

3. VOC Reactivity -- DiurnalDiurnal Mean VOC Diurnal Mean VOC ••OH Loss for G.B. and HoustonOH Loss for G.B. and Houston

Ozo

ne (

Ozo

ne ( p

pbv

ppbv

))

VO

C O

H R

eact

ivity

(sV

OC

OH

Rea

ctiv

ity (s

-- 11))

Other Data:Other Data:

VOC Groups:VOC Groups:

Oxygenates

AlkanesAlkenes

Aromatics

Terpenes,MVK, MCROther Alkenes/Monomers

Other (N, S, Cl, F)

Local Time (CDT) 1 p.m.1 a.m.(UTC)

7 a.m. 6:59 p.m.7 p.m.

3. VOC Reactivity -- Diurnal

•OH Loss Rate for VOCs (s-1) •OH Loss Rate for VOCs (s-1)

Benzene Sources

PITPIT--MS MS 1 min avg.1 min avg.

PITPIT--MS of [Benzene] in HSC transectsMS of [Benzene] in HSC transects

See WelshSee Welsh--Bon et al. poster for more details on PITBon et al. poster for more details on PIT--MSMS

Wind DirectionWind Direction

Wind DirectionWind Direction

HSC transects: PIT-MS

1. VOCs reported represent a vast majority of all VOC •OH reactivity for the >200 compounds observed by GC-FID/MS

• Full Speciation with GC-FID/MS and GC-PIT-MS• Fast Response with PIT-MS and QCL-TILDAS

2. VOCs dominated •OH chemistry in all inland locations 3. The magnitude and variability of the VOC •OH Loss rate

was dependent upon:• Location (emission sources) • VOC composition (primary/fresh vs. secondary/processed) • Time of day (meteorology and emission sources/rates)

VOCs on RHB Summary

High levels of HRVOCs during day or night couldcontribute to ozone exceedances