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Sistema de Información Científica
Red de Revistas Científicas de América Latina y el Caribe, España y Portugal
DERIVATION OF VOLATILE ORGANIC COMPOUNDS SURROGATE FOR THE MAXIMUM
INCREMENTAL OZONE REACTIVITY IN MEXICO CITY METROPOLITAN AREA
José Luis JAIMES-LÓPEZ
*
, Eugenio GONZÁLEZ-ÁVALOS and Marco Antonio RAMÍREZ-GARNICA
Dirección Ejecutiva de Investigación y Posgrado, Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas
Norte 152, Colonia San Bartolo Atepehuacan, México, D. F., C.P. 07730
*Autor de correspondencia:
jjaimes@imp.mx
(Received March 2014; accepted August 2014)
Key words: ozone formation, ambient air, lumped molecule, base mixture
ABSTRACT
Using a method developed by Lurmann
et al.
(1991), for lumped molecule or lumped-
surrogate, we were able to defne the respective base mixture For determining the re
-
activity of volatile organic compounds (VOCs) in ozone formation in the Mexico City
metropolitan area (MCMA). A sampling campaign for collecting VOCs was carried
out to determine the individual compounds in the MCMA atmosphere. Samples were
collected simultaneously in stainless steel canisters at six sites: Xalostoc, Pedregal,
Tlalnepantla, Cerro de la Estrella, Instituto Mexicano del Petróleo, and la Merced.
Seven samples were taken at each site during the sampling period. Ten VOC groups
were established applying the Lurmann methodology, and each group was represented
by one compound as follows: i)
n
-butane For the frst alkane group, ii)
n
-octane for the
second alkane group, iii) ethylene in a group by itselF, iv) propene For the frst olefn
group, v)
t
-2-butene For the second olefn group, vi) toluene For mono alkyl benzenes,
vii) m-xylene for the higher aromatics, viii) formaldehyde in a group by itself, ix)
acetaldehyde for the aldehydes, and x) acetone for the ketones. The surrogate VOC
group (base mixture) was determined, which can be used to experimentally obtain the
ozone formation index of VOCs in the MCMA.
Palabras clave: formación de ozono, aire ambiente, mezcla agrupada sustituta, mezcla base
RESUMEN
La metodología de molécula agrupada o mezcla agrupada sustituta desarrollada por
Lurmann
et al.
(1991) Fue aplicada para defnir la mezcla base representativa en el área
metropolitana de la Ciudad de México (AMCM) con el propósito de determinar la re-
actividad de los compuestos orgánicos volátiles (COV) en la formación de ozono. Para
determinar la concentración de los componentes individuales de los COV, una campaña
de muestreo fue llevada a cabo, utilizando contenedores limpios de acero inoxidable.
Las muestras se recolectaron simultáneamente en seis sitios: Xalostoc, Pedregal, Tlal-
nepantla, Cerro de la Estrella, Instituto Mexicano del Petróleo y la Merced. En cada sitio
se colectaron siete muestras durante el periodo de muestreo. Al aplicar la metodología de
mezcla agrupada sustituta se establecieron 10 grupos y un componente que representó
a cada uno de ellos. Dichos grupos fueron: i) n-butano para el primer grupo alcano,
Rev. Int. Contam. Ambie. 31 (1) 63-77, 2015
J.L. Jaimes-López
et al.
64
ii) n-octano para el segundo grupo alcano, iii) etileno para su propio grupo, iv) propeno
para el primer grupo olefnas, v) t-2-buteno para el segundo grupo olefnas, vi) tolueno
para mono alquil bencenos, vii) m-xileno para aromáticos grandes, viii) formaldehído para
su propio grupo, ix) acetaldehído para los acetaldehídos, y x) acetona para las quetonas.
Se determinó una mezcla de grupos de COV (mezcla base), la cual se propone que sea
utilizada para obtener experimentalmente los índices de reactividad de los COV en la
formación de ozono del AMCM.
INTRODUCTION
Air quality in urban areas is affected by the quan-
tity of ozone (O
3
) formed at ground level. It is a well-
known fact that O
3
is formed from reactions between
volatile organic compounds (VOCs) and nitrogen
oxides (NO
x
) in the gaseous phase under ultraviolet
solar radiation. The main process for forming O
3
at
the lowest level of the Earth’s atmosphere is NO
2
photolysis, which is rapidly reverted when O
3
reacts
with NO
x
. The respective reactions are as follows:
NO
2
+ hg ® O(
3
P) + NO
(1)
O(
3
P) + O
2
+ M ® O
3
+ M
(2)
O
3
+ NO ® NO
2
+ O
2
(3)
where hg is the energy of incident radiation. These
reactions lead to the formation of O
3
in a photo statio-
nary condition, which is regulated by the photolysis
rate of NO
2
and by the NO
2
/NO
x
ratio. If VOCs were
not present in the air, O
3
formation would not be
signifcant. ThereFore, VOCs react to Form radicals
which either consume NO
x
or convert NO
x
into NO
2
.
In addition, O
3
increases when reactions are linked
to the photo stationary condition.
Nevertheless, a number of reactions are involved,
summarized as follows:
VOCs + OH
*
® RO
2
*
+ H
2
O
(4)
RO
2
*
+ NO ® NO
2
+ RO
*
(5)
RO
*
+ O
2
® HO
2
*
+ RO
(6)
HO
2
*
+ NO ® NO
2
+ OH
*
(7)
In these processes, the rate at which O
3
increases
depends on the VOC concentrations, the reaction
constant rates of each VOC, and the radical OH reac-
tivity, as well as those of any other species that could
react with VOCs. Ozone production is maintained
when there is enough NO
x
, and when simultaneous
reactions between peroxide radicals (RO
2
) and NO do
not compete effectively with other peroxide radicals.
Strategies for VOCs control have been developed,
taking into account the different effects on O
3
forma-
tion from all compounds, as well as their reactivities
in the atmosphere. When reaction rates among them
are low because of a highly diluted air mass, or if NO
x
are consumed long beFore the reaction is fnished,
their contribution to O
3
formation can be minimal.
The reactivity level of OH radicals can be the main
parameter due to its in±uence on O
3
formation rates
that are linked to all VOC reactions. In fact, if one
VOC signifcantly aFFected radical inhibition levels,
then the O
3
production rate could be smaller than for
any other VOC not explicitly expressed, even though
the reaction leads to O
3
formation. Therefore, a VOC
usually does not react because of a high and positive
effect of radicals. If VOCs reactions show an upward
trend on the NO
x
removal rates in the system, then
they will show little effect on O
3
formation. The latter
will happen once O
3
formation is limited because of
low NO
x
levels (Carter
et al
. 1995).
The NO
x
availability in the environment is the
most important factor in O
3
formation, because if
NO
x
molecules were absent, O
3
could not be formed,
even when VOCs are present. Therefore, all VOCs
would have reactivity for O
3
formation, even at zero
level. If the NO
x
levels are relatively high, they are
sensitive to VOCs concentration. This means that
total VOCs have the biggest impact on O
3
formation.
Both the radical levels and the period of the O
3
pol-
lution episode are important because they affect O
3
formation, as well as those chemical species with low
reaction rates. This behavior is explained because, at
the highest radical levels in a long pollution episode,
reactions with a low rate contribute to O
3
formation.
As for O
3
control, strategies consider VOCs
reactivity, and point out that the reactivity among
different VOCs is more important than the absolute
impact from only one of them. Some environmental
conditions, such as temperature and concentration
levels, also affect the reactivity of VOCs due to their
VOCs SURROGATE FOR OZONE REACTIVITY IN MEXICO CITY
65
importance on different reaction mechanisms under
specifc conditions. For instance, some parameters,
such as light intensity, temperature, or dilution in
reaction mechanisms affect the NO
x
removal rates,
but do not affect the impact on O
3
that comes from
VOCs in environments abundant in NO
x
. However,
they begin showing a certain effect when NO
x
are
limited.
There are scales assigned to the reactivity of
VOCs, which consist of schemes for assigning
numbers to VOCs to quantify their impact on O
3
formation. A useful scale has been used for analyz-
ing the roles of different VOCs in the environment.
One such scale is the constant rate of the OH radical,
also called the OH constant scale (Chameides
et al
.
1988), which can quantify the VOC reaction rate. In
that case, some VOCs, such as alkenes and aldehydes,
show high constant rates of OH radicals. The use of
constant rates enables the easy estimation of almost
all VOCs, regardless of environmental conditions.
This also works for predicting the relative O
3
impact
from VOCs with very slow reaction rates. However,
because of the mechanistic factors mentioned above,
it is not a satisfactory method for predicting the
relative O
3
impact from VOCs reacting rapidly or
for comparing O
3
impacts from VOCs with similar
constant rates.
As for the regulatory framework, the O
3
impact
(or reactivity) mainly affects the current change in O
3
formation because of VOCs emissions. This change
can be measured using the mean of the “incremen-
tal reactivity,” which is defned as the change in O
3
formation caused by the addition of a small quantity
o± a specifc VOC to the VOCs emissions in an O
3
pollution episode (Carter 1994). According to this
approach, the mixture base for the determination of
the maximum incremental reactivity (MIR) should be
representative of compounds in a certain atmospheric
region. In order to obtain this determination, factors
mentioned previously should be applied. The mixture
base used in experiments with smog chambers to
simulate VOCs in the atmosphere should be repre-
sentative of their effect on reactivity results.
To achieve this goal, there are different points
of view. One of them uses complex mixtures which
have been designed to simulate, as close as possible,
those mixtures present in the atmosphere. Another
consists of very simple mixtures, which are tracers
that are easier to follow experimentally and also
provide a better evaluation of the mechanism tak-
ing into account the effect of different VOCs in the
atmosphere (Lurmann
et al
. 1992). Some studies
were performed in Mexico for monitoring VOCs
concentrations in the ambient air of mega cities, and
many of them focused on the Mexico City metropoli-
tan area (MCMA). Múgica
et al.
(2001) and Vega
et al.
(2000) identifed the VOCs emissions ±rom
different sources and fuels. Also Arriaga-Colina
et
al.
(1997, 2004) carried out monitoring campaigns
to determine VOC concentrations as well as to prove
their great in²uence on O
3
formation.
In this work, the lumped molecule or lumped-
surrogate method developed by Lurmann
et al
. (1991)
was applied for the determination of the base mixture.
A simplifed mixture is generated ±rom the average
data of all VOCs. In this new mixture, a single com-
pound that represents the reactivity of the grouped
molecules is used, and was applied in all of the stud-
ies of smog chambers by Carter (1994) to determine
VOCs reactivity in the United States of America.
The advantage of this method is the representation
of each compound’s group by a single compound,
but showing the reactivity of the total group. As a
result the base mixture designed for carrying out
experiments on VOC reactivity to O
3
formation is
easier to prepare.
MATERIALS AND METHODS
The method used for the determination of the base
mixture of the VOCs came from such a mixture or
from grouped molecules. This requires a represen-
tative compound to be chosen for each molecular
species. Each group is described as follows:
Group #1 (ALK 1) is one group of alkanes. This
group includes alkanes, alcohols, ethers, and other
saturated compounds that react with OH radicals at
constant rates less than 10
4
ppm/min at 300
K.
n
-
butane was chosen to represent this case.
Group #2 (ALK 2) is a second group of alkanes.
It consists of similar compounds, but with constant
rates higher than 10
4
ppm/min. This group is repre-
sented by
n
-octane.
Group #3 (ETHE) is for ethylene only.
Group #4 (OLE 1) is the terminal alkenes. This
includes all alkenes reacting with OH radicals with
constant rates lower than 7.5 × 10
4
ppm/min at 300
K,
including isobutene but not 2-methyl-1-butene. This
group is represented by propene because mechanisms
for other terminal alkenes are derived from this one.
Group #5 (OLE 2) is the internals and dialkenes.
It represents all alkenes that react with OH radicals
with constant rates higher than 10
4
ppm/min at 300
K.
This group includes almost all alkenes with more
than one substituent around the bond (other than
J.L. Jaimes-López
et al.
66
isobutene) and conjugated olefns, such as isoprene. It
also includes the styrenes, because these are grouped
like alkenes in the reaction mechanism.
trans
-2-bu-
tene is used to represent this group.
Group #6 (ARO 1) is the mono alkyl benzenes.
It consists of aromatic hydrocarbons that react with
OH radicals with constant rates lower than 2 × 10
4
ppm/min at 300
K, including benzene and mono alkyl
benzenes. This is represented by toluene, because it
shows dominance in both species.
Group #7 (ARO 2) is the higher aromatics. It
consists of aromatic hydrocarbons that react with OH
radicals at constant rates higher than 2 × 10
4
ppm/min
at 300
K. This group includes xylenes, polyalkyl
benzenes and naphtalenes, and is represented by
m-xylene because its constant rate is closer to the
average of this group than any other isomer of xylene.
Group #8 (HCHO) is for formaldehyde only.
Group #9 (CCHO) is composed of acetaldehyde
and higher aldehydes. RCHO molecules are handled
on a separated condensed mechanism, SAPRC
(Lurmann
et al
. 1991), but almost all of the other
condensed mechanisms are grouped together. It is
represented by acetaldehyde.
Group #10 (ACETONE) is for acetone and higher
ketones. It is represented by acetone.
In the studies of reactivity in smog chambers
made by Carter
et al
. (1995), it was shown that if
the acetaldehyde concentration was replaced by
formaldehyde, the effect on reactivity was small
compared to the signifcant experimental advantages.
This demonstrates that experimental simplifcation
is appropriate.
We carried out a sampling campaign of VOCs to
determine the compounds in the atmosphere of the
MCMA between April 30, 2002 and May 16, 2002
using clean stainless steel canisters. Because of a
stable atmospheric condition prevailing during early
mornings, VOCs concentrations primarily repre-
sented emissions within each site (Wöhrnschimmel
et
al
. 2006). Environmental air samples were collected
simultaneously at six sites: Xalostoc (XAL), Pedre-
gal (PED), Tlalnepantla (TLA), Cerro de la Estrella
(CES), Instituto Mexicano del Petróleo (IMP) and la
Merced (MER;
Fig. 1)
. At each site, seven samples
were taken during the sampling period.
Samples were taken in canisters for three hours in
the morning from 6 to 9 h, and then were analyzed
using the gas chromatography method T-014 (EPA
1995). More than 180 VOCs were detected. Samples
for carbonyl compounds were taken from XAL, PED
and MER. Carbonyls were trapped using cartridges
containing dinitrophenyl hydrazine and were then
quantifed using high-perFormance liquid chroma
-
tography (HPLC, Model 6890, Agilent Technologies)
according to TO-11A (EPA 1999).
RESULTS AND DISCUSSION
The concentrations of VOCs are shown in
Tables I-IV
.
Table I
shows the analytical results
expressed as parts per billion carbon (ppbC) of the
environmental VOCs mixture as well as the overall
average of each VOC species. Total average con-
centrations for some compounds were zero, and
therefore omitted.
Total VOCs levels were signifcantly higher at
TLA (2628.0 ppbC) and XAL (2514.7 ppbC). These
two sites are heavily industrialized and densely
populated in the north part of the MCMA. The low-
est were found at the residential PED site (1054.2
ppbC), in the southwest part of the city. Total VOCs
at MER, IMP, and CES had levels of 2491, 2000.9,
and 2267.9 ppbC, respectively. These values were
2.14 times those of PED. Such a difference among
pollutants in the MCMA is consistent with the fnd
-
ings of Arriaga-Colina
et al
. (2004), taken between
1992 and 2001 in March and November. They also
reported that MER values were 2.1 times higher
than those in PED. Our data collected from early
May 2002 showed concentration levels 35-41 %
lower than those reported by Arriaga-Colina
et al.
(2004) in their March campaigns. This could be
Fig. 1.
Sites of VOCs samplings in the Mexico City metropoli-
tan area. Tlalnepantla (TLA), Xalostoc (XAL), Merced
(MER), Pedregal (PED), Instituto Mexicano del Petróleo
(IMP) and Cerro de la Estrella (CES).
NO
TLA
EAC
ATI
AZC
TAC
CUI
IMP
VAL
TLI
VIF
LLA
SAG
LPR
LVI
ARA
HAN
NET
CHA
LAG
MIN
MER
CUA
PLA
BJU
PED
TAX
CES
UIZ
SUR
TPN
TAH
XAL
NE
SO
SE
CE
VOCs SURROGATE FOR OZONE REACTIVITY IN MEXICO CITY
67
TABLE I.
VOCs AVERAGE CONCENTRATIONS FROM SEVEN DAYS AT SIX SITES, MERCED (MER), XALOSTOC
(XAL), PEDREGAL (PED), INSTITUTO MEXICANO DEL PETRÓLEO (IMP), TLALNEPANTLA (TLA), AND
CERRO DE LA ESTRELLA (CES), IN PARTS PER BILLION CARBON (ppbC)
COMPOUND
MER
XAL
PED
IMP
TLA
CES
Total average
Ethylene
50.4
49.8
21.4
41.5
61.3
60.5
47.5
ARO 135TriMeBenzene
10.5
7.5
3.7
7.7
9.2
8.2
7.8
ARO1,3DiEtBenzene
7.5
7.1
3.4
4.9
4.6
6.7
5.7
ARO1235TeMeBenzene
0.3
0.1
0.0
0.2
0.2
0.2
0.2
ARO123TriMeBenzene
1.1
0.8
0.4
1.4
0.9
0.4
0.8
ARO1245TeMeBenzene
3.7
0.5
1.6
1.6
2.8
4.9
2.5
ARO124TriMeBenzene
24.0
20.6
13.0
1.2
3.1
28.8
15.1
ARO13DiMe4EtBenzene
0.0
0.0
0.0
0.0
0.0
0.1
0.0
ARO4tButToluene
6.3
6.6
2.0
4.2
4.3
4.2
4.6
AROa-Pinene
3.7
9.5
3.7
2.4
0.4
3.9
3.9
AROBenzene
29.7
30.7
11.9
23.0
35.6
28.5
26.6
AROb-Pinene
0.0
0.0
0.0
0.0
0.0
0.5
0.1
AROC10 Aromatic A
0.0
0.0
0.0
0.0
0.0
0.0
0.0
AROC10 Aromatic B
1.8
1.5
0.1
1.7
1.3
0.2
1.1
AROC10 Aromatic C
3.4
1.3
0.7
1.5
1.4
2.4
1.8
AROC10 Aromatic D
0.0
0.0
0.0
0.2
0.0
0.0
0.0
AROC11 Aromatic A
0.0
0.0
0.0
0.0
0.0
0.0
0.0
AROC11 Aromatic B
0.1
0.0
0.0
0.0
0.0
0.0
0.0
AROC12 Aromatic-C
0.7
0.3
0.0
0.5
0.4
0.0
0.3
AROEthylBenzene
21.9
27.1
8.5
22.4
36.4
26.3
23.8
AROiPropBenzene
3.1
2.6
1.2
2.5
4.1
2.9
2.7
AROm/p-Xylene
67.5
94.8
25.7
74.2
125.6
79.0
77.8
AROm-EtToluene
0.0
3.6
0.0
0.0
0.0
0.0
0.6
AROnAmylBenzene
1.1
0.8
0.1
0.7
0.4
0.0
0.5
ARONaphthalene
5.5
4.0
1.9
3.7
3.5
4.6
3.9
AROnButBenzene
10.1
9.6
4.1
7.4
7.1
8.4
7.8
AROnButCyHexane
0.3
1.0
0.0
1.1
0.0
0.4
0.5
AROnPropBenzene
6.0
5.8
2.1
5.1
6.9
5.2
5.2
AROo-EtToluene
7.2
7.1
2.7
6.3
7.8
5.8
6.2
AROo-Xylene+1,1,2,2
27.2
36.2
10.1
28.2
45.1
29.8
29.4
AROp-EtToluene
20.4
16.6
7.2
15.9
19.6
17.8
16.3
AROsecButCyHexane
2.2
2.7
1.1
2.1
1.6
1.5
1.9
AROToluene
138.5
262.0
51.8
147.9
177.4
151.6
154.9
CEMethylEthylCetone
19.1
11.9
0.0
0.0
0.0
0.0
5.2
TOTAL ARO
422.9
572.3
157
368
499.7
422.3
407.0
HA1,1,DiChlorEthan
1.5
0.0
0.1
1.0
0.8
0.4
0.6
HA111trichloEthane
0.0
1.6
0.0
0.0
0.0
0.0
0.3
HA112TriChloroEthane
0.2
0.0
0.1
1.1
0.2
0.0
0.3
HA124TriChloBenz
1.0
0.1
0.1
0.6
0.4
0.0
0.4
HA12DibromoEthane
0.0
0.5
0.0
0.1
0.0
0.0
0.1
HA12DiChloroEthane
12.4
0.0
4.4
9.1
12.7
11.5
8.4
HA12DiChloropropane
0.0
12.0
0.0
0.0
0.0
0.0
2.0
HACarbon TetraChlo
0.0
0.0
0.0
0.0
0.0
0.0
0.0
HACis1,2DiChlorEtha
0.0
0.0
0.0
0.2
0.0
0.0
0.0
HAcis1,3DichloPropene
1.2
0.0
0.0
6.2
2.1
0.0
1.6
HAChloroBenzene
3.6
5.9
1.1
2.8
2.5
3.1
3.2
HAChloroform
14.3
3.6
2.4
19.0
9.1
24.3
12.1
HADichloroEthane
1.0
26.3
0.1
0.8
0.3
0.2
4.8
HAEthyl Chloride
0.0
0.9
0.0
0.0
0.0
0.0
0.2
HAFreon11
0.0
0.0
0.0
0.0
0.0
0.0
0.0
HAFreon113
20.6
0.0
3.5
0.9
0.7
0.9
4.4
HAFreon-114
0.1
12.1
0.0
0.0
0.0
0.0
2.0
HAFreon-12
5.3
0.0
2.1
3.5
7.0
5.4
3.9
J.L. Jaimes-López
et al.
68
TABLE I.
VOCs AVERAGE CONCENTRATIONS FROM SEVEN DAYS AT SIX SITES, MERCED (MER), XALOSTOC
(XAL), PEDREGAL (PED), INSTITUTO MEXICANO DEL PETRÓLEO (IMP), TLALNEPANTLA (TLA), AND
CERRO DE LA ESTRELLA (CES), IN PARTS PER BILLION CARBON (ppbC)
COMPOUND
MER
XAL
PED
IMP
TLA
CES
Total average
HAHexaChlo1,3Butadie
0.0
4.4
0.0
0.0
0.0
0.0
0.7
HAMethyl Bromide
0.0
0.0
0.0
0.0
0.0
0.0
0.0
HAMethylChlor
13.0
0.0
1.4
0.0
0.0
0.0
2.4
HAMethyleneChloride
1.7
6.5
0.2
1.2
1.1
1.9
2.1
HAo-DichloroBenzene
7.0
1.6
1.6
5.5
2.7
2.1
3.4
HAp-DichloroBenzene
7.9
4.8
1.7
4.7
3.1
4.0
4.4
HAPerChlorEthylene
1.7
4.5
0.4
3.3
7.0
1.1
3.0
HATrans13DiChlProp
0.0
3.1
0.0
0.1
0.0
0.0
0.5
HATriChloroEthylene
5.3
0.0
1.7
4.1
3.3
4.7
3.2
HAVinylChlor
0.0
4.8
0.0
0.0
0.0
0.0
0.8
HAVinylidenChlor
0.5
0.0
0.1
1.4
5.2
2.2
1.6
TOTAL HA
98.3
92.7
21.0
65.6
58.2
61.8
66.3
KA1,t2DiMeCyHexane
1.0
0.8
0.1
0.8
0.4
0.0
0.5
KA2,2,5-TriMeHexane
5.5
4.8
2.0
4.3
5.7
5.3
4.6
KA2,2DiMeHeptane
4.3
4.8
4.8
3.2
3.4
1.0
3.6
KA2,3,5TriMeHexane
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KA2,3DiMeHexane
6.7
6.1
2.6
4.6
7.0
6.8
5.6
KA2,3DiMeOctane
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KA2,3DiMePentane
14.9
13.7
5.2
12.5
16.2
14.7
12.9
KA2,4DiMeHeptane
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KA2,4DiMeHexane
11.8
8.7
3.8
6.4
10.3
10.5
8.6
KA2,5DiMeHexane
16.2
10.8
1.1
0.8
0.0
0.0
4.8
KA2,6-DiMeHeptane
1.1
0.9
0.1
1.3
0.7
0.0
0.7
KA2,6DiMeOctane
0.3
0.3
0.3
2.1
1.0
0.0
0.7
KA224TriMePentane
44.9
35.8
18.2
28.5
49.2
48.2
37.5
KA22DiMeButane
13.6
9.8
4.7
7.1
10.9
12.8
9.8
KA234TriMePentane
20.3
16.1
8.1
12.7
20.3
21.9
16.6
KA23DiMeButane
15.8
14.6
5.6
9.9
15.1
13.5
12.4
KA24DiMePentane
11.1
7.0
4.3
6.0
9.4
10.9
8.1
KA2MeHeptane
7.9
8.8
3.1
6.2
9.5
8.9
7.4
KA2MeHexane
0.0
0.0
0.0
0.1
0.0
0.0
0.0
KA2MeNonane
11.0
11.1
4.0
9.7
9.1
9.7
9.1
KA2MePentane
49.2
52.4
19.1
36.7
50.9
45.6
42.3
KA3,3DiMeHeptane
1.0
1.5
0.1
1.4
0.5
0.0
0.8
KA3,3DiMePentane
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KA3,6DiMeOctane
2.6
1.0
0.6
4.5
4.2
1.1
2.3
KA3MeHeptane
7.0
6.7
2.6
5.1
8.1
7.0
6.1
KA3MeHexane
6.9
13.0
1.0
6.9
5.2
3.8
6.1
KA3MeNonane
2.7
3.0
1.0
3.1
2.0
1.7
2.3
KA3MeOctane
5.6
5.4
2.4
4.1
6.3
5.3
4.9
KA3MePentane
26.9
33.2
9.8
21.0
31.8
26.0
24.8
KA4,4DiMeOctane
0.9
0.7
0.1
0.9
0.6
0.0
0.5
KA4Me1Hexane
6.1
6.2
1.9
4.3
5.9
6.0
5.1
KA4MeHeptane
1.7
1.2
0.1
0.4
0.5
0.0
0.7
KA4MeOctane
1.0
0.8
1.5
4.7
1.4
3.0
2.1
KAC10 ParafFn B
3.0
2.8
1.5
4.1
2.0
1.6
2.5
KAC10ParafFn
3.8
4.5
1.7
6.8
3.0
3.3
3.9
KAC11 ParafFn A
1.0
0.7
0.1
1.1
0.7
0.7
0.7
KAC11 ParafFn B
2.9
2.6
1.1
2.6
2.5
2.4
2.4
KAC11 parafFn C
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KAC13 ParafFn-C
0.4
0.0
0.0
0.1
0.2
0.0
0.1
KAC4paraFn
0.0
0.0
0.0
0.3
0.0
0.0
0.1
KAC6 ParaFn A
0.0
0.0
0.0
0.0
0.0
0.0
0.0
VOCs SURROGATE FOR OZONE REACTIVITY IN MEXICO CITY
69
TABLE I.
VOCs AVERAGE CONCENTRATIONS FROM SEVEN DAYS AT SIX SITES, MERCED (MER), XALOSTOC
(XAL), PEDREGAL (PED), INSTITUTO MEXICANO DEL PETRÓLEO (IMP), TLALNEPANTLA (TLA), AND
CERRO DE LA ESTRELLA (CES), IN PARTS PER BILLION CARBON (ppbC)
COMPOUND
MER
XAL
PED
IMP
TLA
CES
Total average
KAC8 Parafn B
1.6
1.4
0.2
1.1
0.9
0.2
0.9
KAC8 Parafn C
2.4
2.7
1.5
4.1
1.4
1.7
2.3
KAC8 Parafn D
10.2
6.7
1.7
2.8
1.8
3.2
4.4
KAC8 Parafn E
1.2
0.9
0.1
0.8
0.8
0.2
0.7
KAC9 Olefn E
0.5
0.0
0.1
0.3
0.3
0.0
0.2
KAC9 ParaFfn B
0.9
0.8
0.0
1.1
0.6
0.0
0.6
KAC9 ParaFfn C
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KAC9 Parafn A
1.2
0.7
0.1
0.8
0.8
0.2
0.6
KACycloHexane
1.5
1.4
0.3
1.4
1.2
0.9
1.1
KACycloPentane
5.4
3.1
2.0
3.2
5.1
4.6
3.9
KACyOctane
1.2
1.4
0.1
1.1
0.4
0.0
0.7
KAiButane
84.9
85.0
43.3
66.3
79.2
70.4
71.5
KAiPentane
126.8
102.4
45.6
69.1
96.7
90.6
88.5
KAMeCyHexane
9.5
7.7
3.9
4.7
10.1
9.7
7.6
KAMeCyPentane
3.7
4.2
1.8
3.7
8.0
3.7
4.2
KAnButane
216.3
204.0
113.5
164.3
272.4
193.7
194.0
KAnDecane+mChloroBenc
7.0
8.1
2.4
7.6
6.3
6.2
6.3
KAnDoDecane
3.3
2.5
0.9
2.6
1.9
1.0
2.0
KAnHeptane
19.9
17.5
5.9
15.5
17.8
13.8
15.1
KAnHexane
28.2
38.1
9.3
24.0
34.6
24.8
26.5
KAnNonane
7.2
8.6
2.4
7.4
7.8
5.9
6.6
KAnOctane
8.1
8.1
2.8
6.4
9.0
7.5
7.0
KAnPentane
56.4
45.7
23.1
45.8
62.5
56.7
48.4
KAnTridecane
0.0
0.2
0.0
0.1
0.0
0.0
0.1
KAnUndecane
4.9
5.0
1.6
4.9
3.4
2.8
3.8
KAPropane
411.6
407.3
236.6
341.1
388.3
374.9
360.0
Ethane
23.5
26.0
9.4
34.4
29.6
16.9
23.3
TOTAL KA
1346.5
1279.3
621.2
1038.9
1334.9
1161.3
1130.4
Acethylene
81.8
80.4
35.4
65.0
89.7
99.3
75.3
KE C7 OleFfn A
0.6
0.0
0.1
3.9
6.2
0.0
1.8
KE C7 OleFfn B
0.0
1.0
0.0
0.5
0.0
0.0
0.3
KE1&2 Butyne
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KE1,3Butadiene
4.9
4.5
1.9
3.7
6.1
5.0
4.4
KE1-Pentene
4.3
4.3
1.6
2.8
5.0
3.7
3.6
KE223TriMe1Butene
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KE233TriMe1Butene
2.4
1.9
0.1
1.6
0.9
0.0
1.2
KE244TriMe1-Pentene
0.7
0.7
0.1
0.7
0.3
0.0
0.4
KE24DiMe1Pentene
0.0
0.0
0.0
0.2
0.0
5.6
1.0
KE2Me1Butene
4.8
3.6
2.0
2.9
5.7
4.9
4.0
KE2Me1Pentene
0.7
0.0
0.0
0.0
0.0
0.0
0.1
KE2Me2Butene
6.8
5.7
2.4
4.2
7.0
6.8
5.5
KE3Me1Butene
1.9
1.7
0.8
1.2
1.1
1.6
1.4
KE4Me1Pentene
4.3
3.9
3.7
4.9
20.6
11.0
8.1
KEC10 OleFfn
10.3
10.2
3.9
9.3
7.7
8.7
8.4
KEC10 Olefn A
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KEC10 ParaFfn
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KEc-2Butene
7.2
6.2
2.2
3.5
4.8
4.2
4.7
KEc-2-Hexene
1.9
2.1
0.2
1.3
1.2
1.1
1.3
KEc-2-Pentene
3.7
3.5
1.2
2.2
3.6
3.0
2.9
KEC4 Olefn A
0.0
0.0
0.0
0.1
0.0
0.0
0.0
KEC4 Olefn B
23.5
0.0
9.2
0.2
28.4
12.9
12.4
KEC5 Olefn A
20.8
0.0
0.0
0.9
0.0
0.0
3.6
KEC5 Olefn B
0.0
0.0
0.0
0.4
0.0
0.0
0.1
J.L. Jaimes-López
et al.
70
TABLE I.
VOCs AVERAGE CONCENTRATIONS FROM SEVEN DAYS AT SIX SITES, MERCED (MER), XALOSTOC
(XAL), PEDREGAL (PED), INSTITUTO MEXICANO DEL PETRÓLEO (IMP), TLALNEPANTLA (TLA), AND
CERRO DE LA ESTRELLA (CES), IN PARTS PER BILLION CARBON (ppbC)
COMPOUND
MER
XAL
PED
IMP
TLA
CES
Total average
KEC6 Olefn
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KEC6 Olefn A
1.2
1.0
0.8
1.2
0.6
1.8
1.1
KEC6 Olefn B
2.4
2.2
1.9
3.4
3.9
4.1
3.0
KEC6 Olefn C
0.0
8.8
0.0
0.0
0.0
0.0
1.5
KEC6 Olefn D
0.2
0.0
0.0
0.4
0.0
0.0
0.1
KEC8 Olefn A
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KEC8 Olefn B
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KEC9 Olefn B
0.0
0.0
0.0
1.4
0.3
0.0
0.3
KEC9 Olefn C
0.2
0.0
0.0
0.4
0.0
0.0
0.1
KEC9 Olefn D
1.8
2.0
0.5
1.9
1.3
1.4
1.5
KECycloPentene
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KEHexene1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KEiButylene+1-Butene
22.8
20.3
9.8
16.3
30.5
22.2
20.3
KEIsoprene
9.4
8.5
2.8
10.3
8.0
10.6
8.3
KENonene-1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
KEPropene
25.6
23.2
15.2
19.6
32.8
30.4
24.5
KEStyrene
8.1
7.2
3.0
12.9
20.9
6.6
9.8
KEt-2-Butene
14.9
16.1
5.2
11.7
14.3
12.8
12.5
KEt-2-Hexene
2.1
2.6
0.3
1.6
1.5
1.8
1.7
KEt-2Pentene
8.5
8.3
2.8
7.5
7.9
7.0
7.0
KEt-3 Octene
4.0
11.3
1.1
4.7
4.2
3.3
4.8
KEt-3-Hexene
0.0
0.0
0.2
0.0
0.9
0.7
0.3
KEtButCyHexane
25.7
28.5
10.4
26.2
29.1
0.0
20.0
TOTAL KE
307.5
269.7
118.8
229
344.5
270.5
256.7
OXI-acetone
10.1
41.4
20.4
34.7
89.5
54.3
41.7
OXI-ethanal
9.2
9.3
8.8
9.7
27.3
17.1
13.6
OXI-Ethanol
11.5
20.9
1.4
11.1
1.0
5.1
8.5
OXIETBE
0.0
0.2
0.0
0.0
0.3
11.4
2.0
OXIMethanol
0.0
10.9
2.1
0.0
0.0
0.0
2.2
OXIMethyl Ethyl Cetone
0.0
0.0
5.5
7.2
8.7
19.2
6.8
OXIMTBE
43.0
38.0
3.1
27.5
40.2
44.4
32.7
TOTAL OXI
73.8
120.7
41.3
90.2
167
151.5
107.4
uncal1
3.5
2.1
0.1
1.6
0.5
1.0
1.5
uncal10
1.4
1.7
1.2
3.1
0.5
0.9
1.5
uncal11
0.5
0.0
0.3
0.4
0.2
0.6
0.3
uncal12
0.3
1.0
0.6
0.3
0.2
10.2
2.1
uncal13
0.7
0.1
5.1
0.7
1.2
0.3
1.4
uncal2
0.8
0.5
0.2
0.3
9.1
0.3
1.9
uncal3
1.5
0.5
1.5
0.4
1.2
0.0
0.9
uncal3
0.4
0.2
12.7
0.1
0.6
0.0
2.3
uncal4
1.1
0.2
0.1
0.0
0.7
0.0
0.4
uncal5
5.1
1.1
0.6
0.3
3.1
0.0
1.7
uncal6
0.1
0.0
0.8
0.1
0.2
0.0
0.2
uncal7
0.1
0.0
0.0
11.1
0.0
0.0
1.9
uncal8
0.5
0.0
0.0
0.3
0.0
0.0
0.1
uncal9
0.4
0.0
0.0
0.0
0.0
0.0
0.1
uncal20
0.0
0.0
0.0
0.6
0.0
0.0
0.1
uncal21
0.0
0.0
0.0
0.1
0.0
0.0
0.0
uncal22
0.0
0.0
0.0
0.5
0.0
0.0
0.1
uncal23
0.0
0.0
0.0
0.9
0.0
0.0
0.2
uncal24
0.0
0.0
0.0
2.3
0.0
0.0
0.4
uncal25
0.0
0.0
0.0
1.7
0.0
0.0
0.3
VOCs SURROGATE FOR OZONE REACTIVITY IN MEXICO CITY
71
TABLE I.
VOCs AVERAGE CONCENTRATIONS FROM SEVEN DAYS AT SIX SITES, MERCED (MER), XALOSTOC
(XAL), PEDREGAL (PED), INSTITUTO MEXICANO DEL PETRÓLEO (IMP), TLALNEPANTLA (TLA), AND
CERRO DE LA ESTRELLA (CES), IN PARTS PER BILLION CARBON (ppbC)
COMPOUND
MER
XAL
PED
IMP
TLA
CES
Total average
uncal26
0.0
0.0
0.0
0.2
0.0
0.0
0.0
uncal27
0.0
0.0
0.0
0.8
0.0
0.0
0.1
TOTAL uncal
16.4
7.4
23.2
25.8
17.5
13.3
17.3
unk
19.3
0.0
0.0
0.0
0.0
0.0
3.2
unk
0.0
0.0
1.4
11.9
0.0
10.1
3.9
unk10
0.4
5.8
4.1
12.9
1.3
4.3
4.8
unk10
0.1
0.0
0.0
0.0
0.0
0.0
0.0
unk11
1.2
2.5
0.0
8.3
0.0
2.2
2.4
unk11
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk11
6.2
2.7
0.3
5.6
2.9
0.7
3.1
unk12
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk12
2.5
3.1
0.9
2.3
2.0
2.9
2.3
unk13
0.0
0.0
0.0
0.0
5.1
0.0
0.9
unk14
4.5
0.7
0.0
7.2
5.5
0.0
3.0
unk15
0.0
1.3
0.3
1.0
2.4
3.2
1.4
unk15
3.0
10.0
2.0
0.8
21.7
0.0
6.3
unk15
0.0
0.2
0.3
0.8
0.0
0.0
0.2
unk16
1.7
4.1
1.8
4.3
3.4
4.1
3.2
unk16
17.8
9.4
5.9
10.2
13.0
15.9
12.0
unk16
0.3
16.9
8.2
18.6
22.5
19.4
14.3
unk16
2.6
10.2
2.3
2.0
1.5
2.5
3.5
unk17
14.8
1.2
0.0
0.4
0.6
2.2
3.2
unk18
18.9
0.0
0.0
0.0
0.0
0.0
3.2
unk19
16.4
1.8
0.5
3.3
2.5
0.8
4.2
unk20
0.9
0.0
0.0
0.0
0.0
0.0
0.2
unk21
0.0
0.0
0.1
0.6
0.2
0.0
0.2
unk22
1.7
0.0
0.0
0.2
0.0
0.0
0.3
unk22
0.0
0.0
2.4
4.1
6.0
6.7
3.2
unk23
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk23
0.0
0.0
0.3
0.8
1.5
0.0
0.4
unk24
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk24
1.0
0.0
0.0
0.0
0.0
0.0
0.2
unk26
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk28
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk29
0.0
1.8
0.4
1.5
1.2
0.7
0.9
unk30
0.6
0.0
0.0
0.0
0.0
0.0
0.1
unk31
5.3
0.3
0.4
0.5
0.0
0.4
1.2
unk32
0.6
0.0
0.0
0.2
0.0
0.0
0.1
unk32
0.0
0.5
0.0
0.7
0.3
0.0
0.3
unk33
0.0
0.0
0.0
0.2
0.0
0.0
0.0
unk33
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk34
1.1
0.0
0.0
0.0
0.0
0.0
0.2
unk34
2.9
1.1
0.1
1.2
0.4
0.0
1.0
unk36
5.4
1.3
1.0
2.0
1.7
2.2
2.3
unk37
1.8
4.0
2.3
4.2
3.5
5.1
3.5
unk37
0.5
0.8
0.3
0.4
1.8
0.7
0.8
unk38
1.4
0.0
0.0
0.0
0.0
5.0
1.1
unk38
0.6
1.8
0.5
3.1
1.7
0.9
1.4
unk38
0.7
1.3
0.1
1.2
0.9
0.0
0.7
unk39
2.7
0.5
0.0
0.9
0.4
0.0
0.8
unk40
3.7
0.9
0.3
0.0
0.0
0.5
0.9
unk41
1.5
4.0
1.2
2.7
2.5
2.5
2.4
unk42
0.0
2.4
1.0
2.4
2.3
1.8
1.7
J.L. Jaimes-López
et al.
72
explained either by the higher ambient temperature
during May, which promotes the dilution of air pol-
lutants early in the morning, or by actual decreases
of vehicle emissions in 2002. Arriaga-Colina
et al.
(2004) always observed a signifcant declining trend
of 21 % for total VOCs at XAL from 1992 to 2001.
This behavior was attributed to the renewal of the
local vehicle Feet as well as the use o± better emis
-
sion control systems and improvements in gasoline
quality (SMA 2006).
Aromatic VOCs concentrations, which impact
O
3
formation, showed higher values (572.3 ppbC) at
XAL, which is situated in an industrial zone charac-
terized by high VOCs emissions, while lower levels
(157.2 ppbC) were found at PED. On average for all
six sites the highest concentrations were reported for
p-xylene, o-xylene, benzene, and ethyl benzene, in that
order. The highest ethylene concentration values were
found at TLA (61.3 ppbC) and CES (60.5 ppbC) and
the lowest at PED (21.4 ppbC). The highest levels of
halogenated VOCs were detected at MER (98 ppbC),
a zone with heavy vehicular tra±fc because it is a
popular commercial zone close to downtown. Par-
a±fnic VOCs were somewhat more concentrated.
Specifcally, propane was reported at 411.6 ppbC
(MER) and butane at 272.4 ppbC (TLA). Total con-
centrations were high at MER (1346.3 ppbC) and
TLA (1334.8 ppbC), and low at PED (621.3 ppbC).
Nevertheless, these compounds have an insignifcant
inFuence on O
3
formation (Carter 1994).
Acetylene (which along with olefns has an appre
-
ciable inFuence on O
3
formation) was detected at the
highest level at CES (99.3 ppbC) and at the lowest
level at PED (35.4 ppbC). The highest total o± olefns
was reported at TLA (344.4 ppbC) and the lowest at
PED (118.9 ppbC). The difference is about 300 %.
Among the olefns, the highest propene concentra
-
tion was at TLA (32.8 ppbC) and the lowest at PED
TABLE I.
VOCs AVERAGE CONCENTRATIONS FROM SEVEN DAYS AT SIX SITES, MERCED (MER), XALOSTOC
(XAL), PEDREGAL (PED), INSTITUTO MEXICANO DEL PETRÓLEO (IMP), TLALNEPANTLA (TLA), AND
CERRO DE LA ESTRELLA (CES), IN PARTS PER BILLION CARBON (ppbC)
COMPOUND
MER
XAL
PED
IMP
TLA
CES
Total average
unk43
2.7
1.6
0.2
1.4
1.2
0.3
1.2
unk43
3.7
0.0
0.0
0.0
0.0
0.0
0.6
unk44
3.4
2.8
0.9
2.1
2.1
1.3
2.1
unk45
0.2
3.9
1.2
2.8
2.8
2.3
2.2
unk46
0.9
8.3
3.7
5.5
16.4
11.4
7.7
unk47
1.5
2.6
1.3
2.2
2.3
2.4
2.1
unk48
5.2
0.0
0.0
0.3
0.0
0.0
0.9
unk49
1.3
0.7
0.3
0.9
0.7
0.2
0.7
unk5
0.2
0.1
0.0
0.0
0.0
0.0
0.1
unk50
2.7
3.8
1.9
3.6
3.5
4.3
3.3
unk51
0.0
1.0
0.2
0.7
0.6
0.2
0.5
unk52
0.6
1.2
0.9
1.4
1.3
1.9
1.2
unk53
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk54
0.0
0.1
0.0
0.3
0.3
0.0
0.1
unk55
0.5
0.1
0.0
0.2
0.1
0.0
0.2
unk56
0.0
5.3
1.1
2.9
4.4
7.1
3.5
unk57
0.0
0.0
0.0
0.2
0.0
0.0
0.0
unk58
0.0
0.2
0.0
0.2
0.0
0.0
0.1
unk59
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk6
3.2
0.0
0.0
0.2
0.0
0.0
0.6
unk60
0.0
0.0
0.0
0.2
0.0
0.0
0.0
unk7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk9
0.0
0.0
0.0
0.0
0.0
0.0
0.0
unk9
1.4
0.5
0.2
0.3
0.4
0.5
0.6
unk9
5.6
0.0
0.0
0.0
0.0
0.0
0.9
TOTAL UNK
175.2
122.8
50.3
141.9
144.9
126.7
127.0
SUM (Ethylene + ARO + HA
+ KA + KE + OXI + unkal
+ unk)
2491.0
2514.7
1054.2
2000.9
2628.0
2267.9
2159.5
VOCs SURROGATE FOR OZONE REACTIVITY IN MEXICO CITY
73
(15.2 ppbC).
t
-Butylcyclohexane was also found in
the highest concentration at TLA (29.1 ppbC) and
at similar levels at MER, XAL, and IMP. The low-
est concentration was found at PED (10.4 ppbC).
Interestingly, HVOC levels in the morning were the
lowest at PED, a site characterized by the highest
frequency of severe O
3
events in the afternoon in
Mexico City. This situation has been explained by
several authors who pointed out that O
3
precur-
sors are transported from the north to the south in
the city. The highest concentration of compounds
with an oxygenated group was reported at TLA
(166.9 ppbC) and the lowest at PED (41.3 ppbC),
a difference of about 400 %. These compounds
have the highest influence on O
3
formation
and represent 6.35 % of total VOCs. Of them,
methyl
t
-butyl ether was present at the highest
concentration (44.4 ppbC) at CES, and MER,
XAL, and TLA had similar values. The lowest
concentration was detected at PED (3.1 ppbC).
Taking into account the total concentration from
all six sites, TLA, MER, and XAL presented the
highest values, at 2500 ppbC, and PED presented
the lowest value (1054.3 ppbC).
Table II
shows the total average concentration of
compounds linked to O
3
formation. Contribution from
TABLE II.
VOCs aVERAGE CONCENTRATIONS OF AROMATICS, HALOGENS, ALKANES, OLEFINS, OXI
GROUP AND UNKNOWN MOLECULES, FROM SEVEN DAYS, ALL SITES, IN PARTS PER BILLION
CARBON (ppbC).
COMPOUND
ppbC
COMPOUND
ppbC
COMPOUND
ppbC
AROMATICS
HALOGENS
ALKANES
Ethylene
47.5
1,1 DiChlorEthane
0.6
1,t-2 DiMeCyHexane
0.5
1,3,5 TriMeBenzene
7.8
1,1,1 trichloEthane
0.3
2,2,5 TriMeHexane
4.6
3 DiEtBenzene
5.7
1,1,2 TriChloroEthane
0.3
2,2 DiMeHeptane
3.6
1,2,3,5 TeMeBenzene
0.2
1,2,4 TriChloBenz
0.4
2,3,5 TriMeHexane
0.0
1,2,3 TriMeBenzene
0.8
1,2 DibromoEthane
0.1
2,3 DiMeHexane
5.6
1,2,4,5 TeMeBenzene
2.5
1,2 DiChloroEthane
8.4
2,3 DiMeOctane
0.0
1,2,4 TriMeBenzene
15.1
1,2 DiChloropropane
2.0
2,3 DiMePentane
12.9
1,3 DiMe4EtBenzene
0.0
Carbon TetraChloride
0.0
2,4 DiMeHeptane
0.0
4 tButToluene
4.6
cis1,2DiChlorEthane
0.0
2,4 DiMeHexane
8.6
a-Pinene
3.9
cis1,3 DichloPropene
1.6
2,5 DiMeHexane
4.8
Benzene
26.6
ChloroBenzene
3.2
2,6 DiMeHeptane
0.7
b-Pinene
0.1
Chloroform
12.1
2,6DiMeOctane
0.7
C10 Aromatic A
0.0
DichloroEthane
4.8
2,2,4 TriMePentane
37.5
C10 Aromatic B
1.1
Ethyl Chloride
0.2
2,2 DiMeButane
9.8
C10 Aromatic C
1.8
Freon11
0.0
2,3,4 TriMePentane
16.6
C10 Aromatic D
0.0
Freon113
4.4
2,3 DiMeButane
12.4
C11 Aromatic A
0.0
Freon-114
2.0
2,4 DiMePentane
8.1
C11 Aromatic B
0.0
Freon-12
3.9
2 MeHeptane
7.4
C12 Aromatic-C
0.3
HexaChlo1,3Butadiene
0.7
2 MeHexane
0.0
EthylBenzene
23.8
Methyl Bromide
0.0
2 MeNonane
9.1
iPropBenzene
2.7
Methyl Chloride
2.4
2 MePentane
42.3
m/p-Xylene
77.8
MethyleneChloride
2.1
3,3 DiMeHeptane
0.8
m-EtToluene
0.6
o-DichloroBenzene
3.4
3,3 DiMePentane
0.0
nAmylBenzene
0.5
p-DichloroBenzene
4.4
3,6 DiMeOctane
2.3
Naphthalene
3.9
PerChlorEthylene
3.0
3 MeHeptane
6.1
nButBenzene
7.8
Trans1,3 DiChlPropane
0.5
3 MeHexane
6.1
nButCyHexane
0.5
TriChloroEthylene
3.2
3 MeNonane
2.3
nPropBenzene
5.2
VinylChloride
0.8
3 MeOctane
4.9
o-EtToluene
6.1
VinylidenChloride
1.6
3 MePentane
24.8
o-Xylene+1,1,2,2
29.4
Total halogens
66.3
4,4 DiMeOctane
0.5
p-EtToluene
16.3
4 Me1Hexane
5.1
secButCyHexane
1.9
4 MeHeptane
0.7
Toluene
154.9
4 MeOctane
2.1
CEMethylEthylCetone
5.2
C10 ParafFn B
2.5
Total aromatics
407.1
C10 ParafFn
3.9
C11 ParafFn A
0.7
C11 ParafFn B
2.4
J.L. Jaimes-López
et al.
74
TABLE II.
VOCs aVERAGE CONCENTRATIONS OF AROMATICS, HALOGENS, ALKANES, OLEFINS, OXI
GROUP AND UNKNOWN MOLECULES, FROM SEVEN DAYS, ALL SITES, IN PARTS PER BILLION
CARBON (ppbC).
COMPOUND
ppbC
COMPOUND
ppbC
COMPOUND
ppbC
ALKANES continuation
OLEFINS
OLEFINS continuation
C11 ParafFn C
0.0
Acethylene
75.3
Nonene-1
0.0
C13 ParafFn C
0.1
C7 OlefFn A
1.8
Propene
24.5
C4
ParaFn
0.1
C7 OlefFn B
0.3
Styrene
9.8
C6
ParaFn A
0.0
1&2 Butyne
0.0
t-2-Butene
12.5
C8
ParaFn B
0.9
1,3 Butadiene
4.4
t-2-Hexene
1.7
C8 ParaFn C
2.3
1-Pentene
3.6
t-2-Pentene
7.0
C8 ParaFn D
4.4
2,2,3 TriMe1 Butene
0.0
t-3-Octene
4.8
C8 ParaFn E
0.7
2,3,3 TriMe1 Butene
1.2
t-3-Hexene
0.3
C9 OleFn E
0.2
2,4,4TriMe1-Pentene
0.4
t-But-Cy-Hexane
20.0
C9 ParafFn B
0.6
2,4 DiMe1 Pentene
1.0
Total olefns
256.7
C9 ParafFn C
0.0
2 Me1-Butene
4.0
C9 ParaFn A
0.6
2 Me1-Pentene
0.1
OXI Group
CycloHexane
1.1
2 Me2-Butene
5.5
Acetone
41.7
CycloPentane
3.9
3 Me1-Butene
1.4
Ethanal
13.6
CyOctane
0.7
4-Me1-Pentene
8.1
Ethanol
8.5
iButane
71.5
C10 OlefFn
8.4
ETBE
2.0
iPentane
88.5
C10 OleFn A
0.0
Methanol
2.2
MeCyHexane
7.6
C10 ParafFn
0.0
Methyl Ethyl Cetone
6.7
MeCyPentane
4.2
C-2-Butene
4.7
MTBE
32.7
n-Butane
194.0
C-2-Hexene
1.3
Total OXI
107.4
n-Decane+mChloroBenzene
6.3
C-2-Pentene
2.9
n-DoDecane
2.0
C4 OleFn A
0.0
Unknown
144.2
n-Heptane
15.1
C4 OleFn B
12.4
n-Hexane
26.5
C5 OleFn A
3.6
Total
2159.5
n-Nonane
6.6
C5 OleFn B
0.1
n-Octane
7.0
C6 OleFn
0.0
n-Pentane
48.4
C6 OleFn A
1.1
n-Tridecane
0.1
C6 OleFn B
3.0
n-Undecane
3.8
C6 OleFn C
1.5
Propane
360.0
C6 OleFn D
0.1
Ethane
23.3
C8 OleFn A
0.0
Total alkanes
1130.4
C8 OleFn B
0.0
C9 OleFn B
0.3
C9 OleFn C
0.1
C9 OleFn D
1.5
Cyclo Pentene
0.0
Hexene1
0.0
iButylene+1-Butene
20.3
Isoprene
8.3
the aromatics, halogens, alkanes, oleFns, OXI group,
and unknown compounds were 19.3, 3.1, 53.5, 12.2,
5.1, and 6.8 %, respectively, showing that alkanes
were the most important compounds.
Table III
contains the speciFed grouped mol
-
ecules (SGM) for each compound, based on
Table II
.
This data was derived according to our ten deFned
groups. The table also shows that in SGM #1, from aro-
matics, alkanes, oleFns, and OXI are 1.3, 5.7, 1.4, and
3.2 times higher, respectively, than those in SGM #2.
Therefore, SGM #1 values were 2.9 times higher than
those in SGM #2.
ALK 1. Though represented by
n
-butane, which
was detected at 194 ppbC
n
-propane was the com-
pound in the highest concentration (360 ppbC).
n
-butane has a higher reactivity than
n
-propane
on the reactivity scale for O
3
formation (Carter
et
al
. 1994).
ALK 2.
n
-octane the representative compound, was
present at 7.0 ppbC. The compound with the highest
VOCs SURROGATE FOR OZONE REACTIVITY IN MEXICO CITY
75
concentration was methyl pentane (42.3 ppbC), and
the total concentration of this group was 184.7 ppbC.
ETHE. Ethylene was present in a concentration
of 47.5 ppbC.
OLE 1. This group is represented by propylene,
which was present in a concentration of 24.5 ppbC.
In this group, acetylene was the most concentrated
molecule at 75.3 ppbC. The total concentration of
OLE-1 was 150.4 ppbC.
OLE 2.
t
-2-butene represents this group and was
present at 12.5 ppbC. Two compounds were of higher
concentrations: isobutylene and 1-butene at 20.3
ppbC and
t
-butylcyclohexane at 20.0 ppbC. Total
concentration for OLE-2 was 106.2 ppbC.
ARO 1. Toluene represents this group and was
present at 154.9 ppbC. At higher concentrations
were benzene and ethyl benzene at 26.6 ppbC and
23.8 ppbC, respectively. The total concentration for
this group was 178.9 ppbC.
ARO 2. The total concentration for this group was
223 ppbC. Compounds with the highest concentration
were m/p-xylene and o-xylene at 77.8 ppbC and 29.4
ppbC, respectively.
HCHO. Formaldehyde was present at a concentra-
tion of 25.1 ppbC.
CCHO. The total concentration for this group was
29.2 ppbC, acetaldehyde was at 14.4 ppbC.
ACETONE. Only acetone and 2-butanone were
detected. The concentration of acetone was 35.5 ppbC
while the total concentration was at 39.2 ppbC.
Table IV
shows the VOCs surrogates for carry-
ing out experiments for O
3
formation in the MCMA
and for determining the MIR for different NO
x
concentrations.
TABLE III.
VOCs aVERAGE CONCENTRATIONS FROM ALL SITES, IN PARTS PER BILLION CARBON (ppbC) AND THE
IDENTIFIED GROUPED MOLECULES (SGM).
AROMATICS
SGM
ppbC HALOGENS
SGM
ppbC
ALKANES (part 1)
SGM
ppbC
Ethylene
47.5
1,1 DiChlorEthane
Ha
0.6
1,t-2 DiMeCyHexane
2
0.5
1,3,5 TriMeBenzene
2
7.8
1,1,1 trichloEthane
Ha
0.3
2,2,5 TriMeHexane
2
4.6
3 DiEtBenzene
2
5.7
1,1,2 TriChloroEthane
Ha
0.3
2,2 DiMeHeptane
2
3.6
1,2,3,5 TeMeBenzene
2
0.2
1,2,4 TriChloBenz
Ha
0.4
2,3 DiMeHexane
2
5.6
1,2,3 TriMeBenzene
2
0.8
1,2 DibromoEthane
Ha
0.1
2,3 DiMePentane
2
12.9
1,2,4,5 TeMeBenzene
2
2.5
1,2 DiChloroEthane
Ha
8.4
2,4 DiMeHexane
2
8.6
1,2,4 TriMeBenzene
2
15.1
1,2 DiChloropropane
Ha
2
2,5 DiMeHexane
2
4.8
4 tButToluene
2
4.6
cis1,2DiChlorEthane
Ha
0.03 2,6 DiMeHeptane
2
0.7
a-Pinene
1
3.9
cis1,3 DichloPropene
Ha
1.6
2,6 DiMeOctane
2
0.7
Benzene
1
26.6
ChloroBenzene
Ha
3.2
2,2,4 TriMePentane
1
37.5
b-Pinene
1
0.1
Chloroform
Ha
12.1
2,2 DiMeButane
1
9.8
C10 Aromatic B
1
1.1
DichloroEthane
Ha
4.8
2,3,4 TriMePentane
1
16.6
C10 Aromatic C
1
1.8
Ethyl Chloride
Ha
0.1
2,3 DiMeButane
2
12.4
C12 Aromatic-C
1
0.3
Freon113
Ha
4.4
2,4 DiMePentane
2
8.1
EthylBenzene
1
23.8
Freon-114
Ha
2
2 MeHeptane
2
7.4
iPropBenzene
1
2.7
Freon-12
Ha
3.9
2 MeHexane
2
0.02
m/p-Xylene
2
77.8
HexaChlo1,3Butadiene
Ha
0.7
2 MeNonane
2
9.1
m-EtToluene
2
0.6
Methyl Chloride
Ha
2.4
2 MePentane
2
42.3
nAmylBenzene
2
0.5
MethyleneChloride
Ha
2.1
3,3 DiMeHeptane
2
0.8
Naphthalene
2
3.9
o-DichloroBenzene
Ha
3.4
3,6 DiMeOctane
2
2.3
nButBenzene
1
7.8
p-DichloroBenzene
Ha
4.4
3 MeHeptane
2
6.1
nButCyHexane
2
0.5
PerChlorEthylene
Ha
3
3 MeHexane
2
6.1
nPropBenzene
2
5.2
Trans1,3 DiChlPropane
Ha
0.5
3 MeNonane
2
2.3
o-EtToluene
2
6.1
TriChloroEthylene
Ha
3.2
3 MeOctane
2
4.9
o-Xylene+1,1,2,2
2
29.4
VinylChloride
Ha
0.8
3 MePentane
1
24.8
p-EtToluene
2
16.3
VinylidenChloride
Ha
1.6
4,4 DiMeOctane
2
0.5
secButCyHexane
2
1.9
Total halogens
66.3
4 Me1Hexane
2
5.1
Toluene
1
154.9
4 MeHeptane
2
0.7
CEMethylEthylCetone
1
5.2
4 MeOctane
2
2.1
ARO
1
228.2
C10 ParafFn B
1
2.5
ARO
2
178.9
Part 1 ALK 1
91.1
ARO 1 + ARO 2
407.1
Part 1 ALK 2
152.0
Part 1 (ALK 1 + ALK 2)
243.2
J.L. Jaimes-López
et al.
76
CONCLUSIONS
We provide a base mixture for performing experi-
ments for determining O
3
formation indices of VOCs
in the MCMA. Reactivity of lumped-surrogates (base
mixtures) in this study should be very similar to that
found in the MCMA atmosphere. The NO
x
concen-
trations are also representative of the data collected
during VOC sampling. The surrogate base mixture
(
Table 4
) can be used in experiments for determining
O
3
formation from each VOC to generate better and
more reliable results. As a consequence, decisions
will be more effective for air quality improvement
in macro cities. Finally, the base mixtures obtained
in this study allow experimental work to be carried
out for determining the VOCs reactivity indices for
O
3
formation. Therefore, indices currently applied in
the MCMA, obtained by Carter
et al.
(1994) in the
United States of America, can be replaced by indices
determined from the application of this study.
TABLE III.
VOCs aVERAGE CONCENTRATIONS FROM ALL SITES, IN PARTS PER BILLION CARBON (ppbC) AND THE
IDENTIFIED GROUPED MOLECULES (SGM).
ALKANES (part 2)
SGM
ppbC OLEFINS
SGM
ppbC
OXI
SGM
ppbC
C10 ParafFn
1
3.9
Acethylene
1
75.3
Ethanal
2
13.6
C11 ParafFn A
1
0.7
C7 OlefFn A
1
1.8
Ethanol
1
8.5
C11 ParafFn B
1
2.4
C7 OlefFn B
1
0.3
ETBE
2
2.0
C13 ParafFn C
1
0.1
1,3 Butadiene
2
4.4
Methanol
1
2.2
C4
ParaFn
1
0.1
1-Pentene
1
3.6
Methyl Ethyl Ketone
1
6.8
C8
ParaFn B
1
0.9
2,3,3 TriMe1 Butene
2
1.2
MTBE
1
32.7
C8 ParaFn C
1
2.3
2,4,4TriMe1-Pentene
2
0.4
OXI
1
50.1
C8 ParaFn D
1
4.4
2,4 DiMe1 Pentene
2
1.0
OXI
2
15.6
C8 ParaFn E
1
0.7
2 Me1-Butene
2
4.0
OXI 1 + OXI 2
65.7*
C9 OleFn E
1
0.2
2 Me1-Pentene
2
0.1
Acetone
41.7
C9 ParafFn B
1
0.6
2 Me2-Butene
2
5.5
Acetone
A
38.0
C9 ParaFn A
1
0.6
3 Me1-Butene
1
1.4
2-Butanone
A
3.7
CycloHexane
1
1.1
4-Me1-Pentene
2
8.1
Unknown
144.2
CycloPentane
1
3.9
C10 OlefFn
1
8.4
Sum
251.6
CycloOctane
1
0.7
c-2-Butene
2
4.7
Ibutane
1
71.5
c-2-Hexene
2
1.3
* Included in
IPentane
1
88.5
c-2-Pentene
2
2.9
ALK 1 and ALK 2
MeCycloHexane
1
7.6
C4 OleFn A
2
0.0
MeCycloPentane
1
4.2
C4 OleFn B
1
12.4
Formaldehyde
F
25.1
n-Butane
1
194.0
C5 OleFn A
2
3.6
Acetaldehyde
C
14.4
n-Deca+mChloroBenzene
2
6.3
C5 OleFn B
1
0.1
Propionaldehyde
C
3.5
n-DoDecane
1
2.0
C6 OleFn A
1
1.1
Crotonaldehyde
C
1
n-Heptane
1
15.1
C6 OleFn B
2
3.0
Metacrolein
C
0.5
n-Hexane
1
26.5
C6 OleFn C
1
1.5
n-Butiraldehyde
C
0.5
n-Nonane
1
6.6
C6 OleFn D
1
0.1
Valeraldehyde
C
3.8
n-Octane
2
7.0
C9 OleFn B
2
0.3
Benzaldehyde
C
3.2
n-Pentane
1
48.4
C9 OleFn C
1
0.1
Hexanel
C
2.2
n-Tridecane
1
0.1
C9 OleFn D
2
1.5
m,p-Tolualdehyde
C
0.1
n-Undecane
2
3.8
iButylene+1-Butene
1
20.3
Acetaldehyde
C
29.2
Propane
1
360.0
Isoprene
2
8.3
Aldehydes
54.3
Ethane
1
23.3
Propene
1
24.5
Part 2 ALK 1
870.2
Styrene
2
9.8
TOTAL
2159.5
Part 2 ALK 2
17.0
t-2-Butene
2
12.5
Part 2 (ALK 1 + ALK 2)
887.2
t-2-Hexene
2
1.7
Part 1 + Part 2
1130.4 t-2-Pentene
2
7.0
t-3-Octene
2
4.8
t-3-Hexene
2
0.3
t-But-Cy-Hexane
2
20.0
OLE
1
150.7
OLE
2
106.0
OLE 1 + OLE 2
256.7
VOCs SURROGATE FOR OZONE REACTIVITY IN MEXICO CITY
77
REFERENCES
Arriaga-Colina J.L., Escalona S., Cervantes A., Orduñez R.
and Limón T. (1997). Seguimiento de COV en el aire
urbano de la ZMCM. 1992-1996. In: Contaminación
Atmosférica. Vol. 2 (L.G. Colín, J. Varela, Eds.),
1ª ed.
El Colegio Nacional, México D.F., pp. 69-76.
Arriaga-Colina J.L., West J.J., Sosa G., Escalona S.S.,
Orduñez R.M. and Cervantes A.D.M. (2004). Mea-
surements of VOCs in Mexico City (1992-2001) and
evaluation of VOCs and CO in the emissions inventory.
Atmos. Environ.
38, 2523-2533.
Carter W.P.L. (1990). A detailed mechanism for the gas-
phase atmospheric reactions of organic compounds.
Atmos. Environ. Part A, General Topics. 24, 481-518.
Carter W.P.L. (1994). Development of ozone reactivity
scales for volatile organic compounds. J. Air Waste
Manag. Assoc. 44, 881-889.
Carter W.P.L., Lou D., Markina I.L. and Pierce J.A.
(1995). Environmental chamber studies of atmospheric
reactivities of volatile organic compounds. Effects
of varying ROG surrogate and NOx. Final Report.
Statewide Air Pollution Research Center and College
of Engineering. Center for Environmental Research
and Technology. University of California, Riverside,
CA, USA, 137 pp. [online] citeseerx.psu.edu.
Chameides W.L., Lindsay R.W., Richardson J. and Kiang
C.S. (1988). The role of biogenic hydrocarbons in
urban photochemical smog: Atlanta as a case of study.
Science 241, 1473-1475.
TABLE IV.
VOCs SURROGATES FOR EXPERIMENTS IN
THE MEXICO CITY METROPOLITAN AREA
Compounds
Concentration (ppbC)
n-Butane
1011.3
n-Octane
184.7
Ethylene
47.5
Propylene
150.4
Trans 2-Butene
106.2
Toluene
228.2
m-Xylene
178.9
Formaldehyde
25.1
Acetaldehyde
29.2
Acetone
41.7
TOTAL
1949.0
Unknown (144.2 ppb C) + Halogens (66.2 ppb C) + Total VOCs
from Table IV (1949.0 ppb C) = 2159.5 ppbC.
Aldehydes (Formaldehyde + acetaldehyde) were analyzed by
liquid chromatography and then added to VOCs (54.3 ppb C).
EPA (1995). Analysis of volatile organic compounds
from polished stainless steel pasivated canisters by
EPA method
TO-14/TO-15. Environmental Protec-
tion Agency. Research Triangle Park Laboratories,
EPA (1999). Compendium of methods for the determi-
nation of toxic organic compounds in ambient air.
Compendium method TO-11A-determination of
formaldehyde in ambient air using adsorbent cartridge
followed by high liquid chromatography (HPLC).
2
nd
ed. Environmental Protection Agency. [online]
Vega E., Múgica V., Reyes E., Sánchez G., Chow J. and
Watson J. (2000a). Differences of 1996 and 1997
source contributions of volatile organic compounds
in Mexico City. In: Air Pollution VIII. (J.W.S. Lon-
ghurst, C.A. Brebbia and H. Power, Eds.) Wit Press,
Southampton, U.K., V. 8, pp. 109 -119.
Lurmann F.W., Gery M. and Carter W.P.L. (1991). Imple-
mentation of the 1990 SAPRC chemical mechanism
in the urban airshed model. Final Report. California
South Coast Air Quality Management District, So-
noma Technology, Inc. Report STI-99290-1164-FR,
Santa Rosa, CA, USA. [online] http://www.engr.ucr.
edu/~carter/pubs/s99doc.pdf.
Lurmann F.W, Main H.H., Knapp K.T., Stockburrger L.,
Ramussen R.A. and Fung K. (1992). Analysis of ambi-
ent VOC data collected in the Southern California Air
Quality Study. Final Report. California Air Resources
Board, Contract No. A 382-130; Research Division,
Sacramento, CA, USA. [online] http://www.osti.gov/
scitech/biblio/5985200#.
Múgica V., Vega E., Sánchez G., Reyes E., Chow J.,
Watson J., Egami R. and Arriaga J.L. (2001). Volatile
organic compounds emissions from gasoline and diesel
powered vehicle. Atmósfera 14, 29-38.
SMA, Sistema de Monitoreo Atmosférico (2006). Gestión
ambiental del aire en el Distrito Federal: Avances y
propuestas 2000-2006. Secretaría del Medio Ambiente,
Gobierno del Distrito Federal, Ciudad de México.
255 pp.
Wöhrnschimmel H., Márquez C., Mugica V., Stahel W.A.,
Stahelin J., Cárdenas B. and Blanco S. (2006). Verti-
cal profles and receptor modeling oF volatile organic
compounds over Southeastern Mexico City. Atmos.
Environ. 40, 5125-5136.
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