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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
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.
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
Recommended