Seasonal variability of 1-chloropyrene on atmospheric particles and photostability in toluene

Article abstract of DOI:10.1016/j.chemosphere.2004.08.069

The occurrence of a mutagenic compound, 1-chloropyrene (Cl-Py), in extracts of ambient particulate matter at an urban site in Japan has been investigated. Samples were collected with a high-volume air sampler for 24 h periods over the course of 1 week in winter (February), spring (May), summer (August), and autumn (November) 2002. The Cl-Py levels showed seasonal variation, ranging from 2.4 pg/m³ (summer) to 18.9 pg/m³ (winter). This variation would indicate that the lower temperatures in winter results in an increased distribution of Cl-Py from vapor phase to the particle phase. In addition, there is also the possibility that ambient Cl-Py is emitted from seasonal sources or is susceptible to photodegradation by sunlight, or both. The photodegradation of Cl-Py in a laboratory experiment was conducted to simulate the compound's fate on airborne particle surfaces. The degradation of Cl-Py proceeded by a first-order reaction with a rate constant of 0.72 h^-1. In the presence of a radical sensitizer, 9,10-anthraquinone (AQ), the photodegradation rate of Cl-Py was elevated in comparison with the rate in the absence of AQ. In addition, the dechlorination of Cl-Py (i.e., the formation of Py) occurred in the presence of AQ.

Full text of DOI:10.1016/j.chemosphere.2004.08.069

Chemosphere 57 (2004) 831–837
www.elsevier.com/locate/chemosphere
Seasonal variability of 1-chloropyrene on atmospheric
particles and photostability in toluene
*
Takeshi Ohura , Atsushi Kitazawa, Takashi Amagai
Institute for Environmental Sciences, University of Shizuoka, 52-1, Yada, Shizuoka 422-8526, Japan
Received 23 December 2003; received in revised form 30 July 2004; accepted 23 August 2004
Abstract
The occurrence of a mutagenic compound, 1-chloropyrene (Cl-Py), in extracts of ambient particulate matter at an
urban site in Japan has been investigated. Samples were collected with a high-volume air sampler for 24h periods over
the course of 1 week in winter (February), spring (May), summer (August), and autumn (November) 2002. The Cl-Py
levels showed seasonal variation, ranging from 2.4pg/m3 (summer) to 18.9pg/m3 (winter). This variation would indicate
that the lower temperatures in winter results in an increased distribution of Cl-Py from vapor phase to the particle
phase. In addition, there is also the possibility that ambient Cl-Py is emitted from seasonal sources or is susceptible
to photodegradation by sunlight, or both. The photodegradation of Cl-Py in a laboratory experiment was conducted
to simulate the compoundÕs fate on airborne particle surfaces. The degradation of Cl-Py proceeded by a first-order reac-
tion with a rate constant of 0.72hꢀ1. In the presence of a radical sensitizer, 9,10-anthraquinone (AQ), the photodegra-
dation rate of Cl-Py was elevated in comparison with the rate in the absence of AQ. In addition, the dechlorination of
Cl-Py (i.e., the formation of Py) occurred in the presence of AQ.
ꢀ 2004 Elsevier Ltd. All rights reserved.
Keywords: 1-Chloropyrene; Particulate matter; PAHs; Photodegradation; Radical sensitizer
1. Introduction
tors into various environments (Alcock and Jones,
1996; Baker and Hites, 2000). The productions such
PCDDs and PCDFs substantially make progress in the
presence of organic compounds containing chlorine
(Addink and Olie, 1995; Takasuga et al., 2000). Polycy-
clic aromatic hydrocarbons (PAHs) are also generated
by the combustion of organic compounds and are
known to be carcinogenic and mutagenic (Mastral and
Organochlorine compounds as typified by polychlo-
rinated dibenzo-p-dioxins (PCDDs) and polychlorinated
dibenzofurans (PCDFs) have caused much concern,
owing to their reproductive toxicity and carcinogenicity
to humans (Fingerhut et al., 1991; IARC, 1997; US
EPA, 1997). Their main source appears to be refuse
incineration, and the compounds diffuse from incinera-
´
Callen, 2000; Richter and Howard, 2000; Bostro¨m
et al., 2002). Considering the process by which those
compounds are produced, chlorinated PAHs (Cl-PAHs)
may also be produced concurrently with them. Yoshino
and Urano (1997) have confirmed the presence of Cl-
PAHs in exhaust gas from municipal waste incinerators.
In addition, Weber et al. (2001) have reported a possible
*
Corresponding author. Tel.: +81 54 264 5789; fax: +81 54
264 5798.
E-mail address: ooura@smail.u-shizuoka-ken.ac.jp (T.
Ohura).
0045-6535/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.chemosphere.2004.08.069

832
T. Ohura et al. / Chemosphere 57 (2004) 831–837
pathway for the formation of PCDFs from Cl-PAHs
during incineration processes. With respect to the envi-
ronmental distribution of Cl-PAHs, the presence of Cl-
PAHs in tap water has been demonstrated (Shiraishi
et al., 1985). The levels ranged from 0.1 to 0.01ng/l for
10 species of Cl-PAHs, which Shiraishi et al. suggest
were produced by the use of chlorine for the disinfection
of public water supplies. However, little is known about
the atmospheric behavior, fate, and potential degrada-
tion pathway of Cl-PAHs.
peak was isolated and analyzed by a Hewlett–Packard
(HP) 6890 gas chromatography–HP 5972 A mass spectr-
ometry (GC–MS) (Agilent Technologies, Palo Alto, CA,
1
USA) and H-NMR (JEOL JNM-GSX500 spectrome-
ter). The analytical condition of GC–MS was showed
in the section of Analytical procedure in detail. The
mass spectrum of this compound contained a base peak
at m/z = 236 (likely the molecular ion) and other pro-
minent peaks at m/z = 200 (M-HCl), 118, and 100. The
1H-NMR (500MHz, CDCl3) peaks identified are as fol-
lows: d: 8.03–8.11 (m, 5H), 8.19–8.24 (m, 3H), 8.48 (d,
1H). On the basis of these analytical results, the isolated
product was identified as Cl-Py. GC–MS indicated a
purity of >95% (by area).
With respect to the mutagenicity of Cl-PAHs, Col-
msjo¨ et al. (1984) have reported that 1-chloropyrene
(Cl-Py) shows an S9-dependent mutagenic effect in the
Salmonella system, although pyrene, the parent com-
pound, shows only weak mutagenicity. The increased
mutagenicity of Cl-Py seems to be due to the epoxidation
facilitated by introduction of chlorine into the molecule.
The main degradation pathway for PAHs and nitro-
PAHs is driven by sunlight (Kamens et al., 1988; Fan
et al., 1996). The photodegradation mechanisms have
been investigated in laboratory experiments using chem-
ical model systems as proxies for the organic phase of
ambient aerosols (McDow et al., 1994; Jang and
McDow, 1995; Feilberg and Nielsen, 2000; Feilberg
and Nielsen, 2001). These studies indicate that photo-
degradation is likely to occur via an indirect pathway
involving radical sensitizers such as polycyclic aromatic
quinones.
2.2. Sampling procedure
Monitoring was conducted at a rooftop location
(20m above ground level) on the University of Shizuoka
campus (lat 34ꢁ590 N, long 138ꢁ270 E) situated ꢁ1km
from the nearest busy road and ꢁ6km from the city cen-
ter. Particulate matter was collected on glass fiber filters
(20.3 · 25.4cm; Type A/E Gelman Sciences Inc., Ann
Arbor, MI, USA) by a high-volume air sampler (SIBA-
TA Scientific Technology Ltd., Tokyo, Japan). The sam-
pler operated at a constant flow rate of ꢁ1.0m3/min.
Samples were collected over a period of 24h, yielding
sampled air volumes of ꢁ1440m3, for 7 consecutive days
during 4 months: February (winter), May (spring), Au-
gust (summer), and November (autumn) 2002. The sea-
sonal concentrations were calculated from the total of
the 7 days for each season. After the samples were taken,
the filters were wrapped in aluminum foil and stored in a
freezer at ꢀ45ꢁC until they were extracted.
In the current work, we investigated the occurrence
of Cl-Py, a representative of the Cl-PAH group, in ex-
tracts of particles collected at an urban site in Shizuoka,
Japan, and compared the observed levels with the PAH
levels. We also studied the photostability of Cl-Py in
chemical model systems both in the presence and in
the absence of a photochemical radical sensitizer, 9,10-
anthraquinone (AQ).
2.3. Extraction and clean-up
2. Experimental
During the entire treatment procedure, the samples
were protected from light to avoid photochemical degra-
dation of the analytes. The filters were extracted ultra-
sonically with 50.0ml of dichloromethane containing
phenanthrene-d10 (63ng) and perylene-d12 (155ng) as
internal standards. The extraction lasted 20min. After
centrifugal separation (10min, 3000rpm), 40ml of the
supernatant fluid solution was used as the sample solu-
tion. It was concentrated to ꢁ5ml in a rotary evaporator
and then blown down to ꢁ1ml under a gentle stream of
N2 through an XAD-2 resin to trap impurities at 30ꢁC.
The concentrated solution was cleaned up by means of a
glass solid-phase extraction tube (SUPELCO, Inc.,
Bellefonte, PA, USA) packed with silica (500mg; parti-
cle size, 40lm; SUPELCO), which was eluted with
10ml mixed solvent of n-hexane and dichloromethane
(9:1 v:v). The eluate was concentrated to ꢁ300ll under
a gentle stream of N2 at 30ꢁC for GC–MS analysis.
2.1. Synthesis of 1-chloropyrene
Cl-Py was synthesized by the chlorination of pyrene
(Py) (Wako Chemicals, Osaka, Japan) with N-chloro-
succinimide (NCS) (Wako Chemicals) following the pro-
cedure of Dewhurst and Kitchen (1972). A solution of
NCS (2.0g) in 20ml propylene carbonate (PC) and a
solution of Py (2.0g) in 20ml PC were mixed and al-
lowed to react at 100ꢁC for 3h in the dark. The reaction
solvent was fractionated by HPLC (Waters 515, Waters,
Milford, MA) using
a
COSMOSIL 5C18-AR
(20 · 250mm; Nacalai Tesque, Inc., Kyoto, Japan) col-
umn and methanol as an eluent, and a flow rate of
10.0ml/min. The reaction products were detected by
UV/VIS detector (Waters 2487) at the wavelength of
245nm. The fraction corresponding to the dominant

T. Ohura et al. / Chemosphere 57 (2004) 831–837
833
Particulate PAHs were extracted with dichlorometh-
ane. PAHs were also extracted in an ultrasonic bath for
20min. After centrifugation at 3000rpm for 10min, a
known volume of extract was transferred to another test
tube. DMSO (50ll) was then added to preserve the
PAHs, and the solvent was evaporated under N2. The
residues were then dissolved in 950ll of acetonitrile,
and the target PAHs were separated by HPLC.
in the atmosphere. The photoreactor was positioned in
a water bath with constant water circulation. The tem-
perature in the water bath was maintained at
25 1ꢁC. The solutions were irradiated in 13 · 100mm
quartz reaction tubes.
The synthesized Cl-Py was dissolved in toluene at a
concentration of ꢂ0.15mM. Samples were removed with
a pipette and transferred to brown chromatography
vials. The samples were analyzed for identification of
the photolysis products using the GC–MS condition as
showed in section of Analytical procedure, but in scan
mode. Experiments were carried out both in pure solu-
tion and in the presence of AQ as a radical sensitizer.
2.4. Analytical procedure
Analysis of Cl-Py was performed on a HP 6890 GC–
HP 5972A MS system. The capillary column was a DB-5
(5%
phenyl-methylpolysiloxane,
60m · 0.32mm ·
0.25lm, J&W Scientific). Helium was used as a carrier
gas at a flow rate of 1.0ml/min. The oven temperature
was kept at 80ꢁC for 2min, then increased from 80ꢁC
to 300ꢁC at a rate of 5ꢁC/min, and then kept 300ꢁC
for 20min. The temperature of the injector and GC–
MS transfer line was kept at 300ꢁC. The MS detector
was run in electron impact ionization mode, and the
electron energy was 70eV. Qualification of Cl-Py was
performed in selected-ion monitoring mode using the
molecular ions 236 and 238.
3. Results and discussion
3.1. Concentration of Cl-Py
The detection limit for Cl-Py for our method was de-
fined as 3 times the standard deviation of the peak area
of a dilute standard solution, which was established as
0.72pg/m3 in terms of ambient concentration. When lab-
oratory blanks were analyzed by the established method,
Cl-Py was not detected. Recovery tests of Cl-Py from
particles were 91 14%. Reproducibility tests indicated
that the coefficient of variation of Cl-Py concentrations
was less than 26%.
The PAHs were separated on an HPLC system con-
sisting of an L-6000 series pump, an L-5090 degasser, an
AS-2000 autosampler, an F-1080 spectrofluorometer
(Hitachi Corp., Tokyo, Japan), a mixer (Agilent Tech-
nologies), a CO630 column oven, and a six-way valve
(GL Science Corp., Tokyo, Japan). The precolumn
(4.6-mm i.d. · 30mm) for PAH condensation and
clean-up and the main column (4.6-mm i.d. · 250mm)
for PAH separation were Wakosil-II 5C-18 PAH (Wako
Chemicals). PAHs were detected by two spectrofluorom-
eters connected in series, with detection wavelengths
automatically changing during analysis. The HPLC ana-
lytical conditions have been described elsewhere (Ohura
et al., 2002; Ohura et al., 2004). The following PAHs
were monitored: pyrene (Py), benz[a]anthracene (BaA),
benzo[a]pyrene (BaP), and benzo[ghi]perylene (BghiP).
The recovery test was carried out the addition of Cl-
Py solution (1.4ng) as the spike to the collected filter
samples, followed by the extraction and analysis as de-
scribed in above.
Ambient particle samples from the four seasons were
extracted and analyzed for Cl-Py. Cl-Py was detected in
all the samples, indicating its ubiquitous distribution.
The ambient levels ranged from 2.4 (summer) to 18.9
(winter)pg/m3 (Fig. 1). The levels observed in spring
and autumn were 2.6 and 4.4pg/m3, respectively. The
mean value for the four seasons was 7.1pg/m3, which
was somewhat higher than the values for particle sam-
ples collected from an urban street, 4.9pg/m3 (Nilsson
¨
and Ostman, 1993). The concentrations of Cl-Py associ-
ated with particles were higher in winter and autumn
than in summer and spring. Similar trends for PAHs
associated with particles were also observed in this study
(Fig. 1). In addition, we observed significant correlation
over the seasons between the concentrations of Cl-Py
and Py associated with particles (p < 0.01) (data not
shown). These facts indicate that the behavior of Cl-Py
in air may be similar to that of the parent compound,
Py, although their concentration levels differ considera-
bly. The ratio of the maximum value to the minimum
value (the concentration ratio of winter/summer) for
Cl-Py was 7.9, although the ratios for the PAHs ranged
from 2.0 to 5.9. The larger variability of the Cl-Py con-
centration may indicate that the lower temperatures in
winter results in an increased distribution of Cl-Py from
vapor phase to the particle phase as shown in the case of
ambient PAHs (Ohura et al., 2002; Ohura et al., 2004).
In addition, there is also the possibility that the ambient
2.5. Photodegradation experiments
Photodegradation experiments were performed with
a turntable photoreactor using a 450-W high-pressure
mercury lamp (USHIO Co., Ltd., Tokyo, Japan) as
the light source. The lamp was placed in a quartz immer-
sion well with cooling water. The immersion well was
surrounded by a Pyrex sleeve to filter out high-energy
UV bands (k > 290nm). Although this setup does not
resemble the spectral distribution of the actinic flux, it
does reproduce the wavelengths normally encountered

834
T. Ohura et al. / Chemosphere 57 (2004) 831–837
Fig. 1. Comparison of the Cl-Py and PAH levels for each sampling season.
0.5
0
Cl-Py levels were strongly dominated by the possible
seasonal sources, or by photochemical degradation dur-
ing periods of high solar radiation. On the other hand,
secondary reactions in air may be another source of
Cl-Py because it is formed easily by the photochemical
chlorination of pyrene (Nilsson and Colmsjo¨, 1989,
-0.5
-1
¨
1990). Nilsson and Ostman (1993) suggest that automo-
-1.5
-2
bile traffic may be a major source of Cl-PAHs in the
street environment, because the concentration profiles
of Cl-PAH in street and road tunnel samples were sim-
ilar. Municipal waste incineration plants, a major source
of atmospheric PCDDs/PCDFs, may also be a source of
Cl-PAH. It is therefore difficult to determine the impor-
tance of the various sources; further investigation will be
needed to clarify the behavior and occurrence of Cl-
PAH species.
Py
-2.5
-3
Cl-Py
Cl-Py+AQ (5mM)
-3.5
0
20
40
60
80
100
120
140
Time (min)
Fig. 2. Photostability of Cl-Py (in the presence and absence of
AQ) and Py in toluene, expressed as ln(C/C0) vs. time. The solid
lines are linear regressions of the data.
3.2. Photostability of Cl-Py
In order to clarify the photostability of Cl-Py, we
simulated the photodecay in laboratory experiments
using chemical model systems. Fig. 2 shows the time
dependence of the decay of Cl-Py and Py in toluene dur-
ing the irradiation. Decay of Cl-Py and Py apparently
can be described by first-order kinetics, and Py was more
stable than Cl-Py during the course of the experiment.
This result indicates that the addition of a chlorine atom
to Py accelerated the photodecay. The rate constants,
linear regression coefficients (R2), and half-lives for the
degradation of Cl-Py, Py, and 1-nitropyrene (1NP) are
compared in Table 1. The rate constant for the degrada-
tion of Cl-Py was significantly smaller than that of 1NP,
which has been suggested to be emitted directly from
vehicles and distributed ubiquitously in air (Feilberg
et al., 2001). Hayakawa et al. (1995) detected ambient
1NP levels that were nearly 3 orders of magnitude higher
than the levels of Cl-Py we observed in this study. The
Table 1
First-order decay rate constants and half-lives of Py derivatives
Compound
k (hꢀ1
)
R2
t1/2 (h)
Py
1NP
0.44
15
0.914
0.945
0.976
0.991
1.58
0.05
0.96
0.50
Cl-Py
Cl-Py + AQ
0.72
1.38
low atmospheric levels of Cl-Py that we measured can-
not be explained by the photodegradation and must
therefore have been caused by low emission rates.
With regard to the direct photolysis of PCDDs/
PCDFs, as chlorinated aromatic compounds that can
undergo reductive dechlorination followed by further

T. Ohura et al. / Chemosphere 57 (2004) 831–837
835
reaction steps, the extent of dechlorination has occurred
0.05
0.04
0.03
0.02
0.01
0
0.012
0.008
0.004
0
in less than 20% (Kim and OÕKeefe, 2000). In the case of
photolysis of Cl-Py, we observed no pyrene produced by
reductive dechlorination during the irradiation. In addi-
tion, we did not find significant photolysis products
resulting from Py irradiation. These results suggest that
C-Py undergoes fragmentation immediately upon irradi-
ation. Also, Kim and OÕKeefe (2000) reported that
dechlorination of PCDD/Fs was accelerated by the use
of solvents with greater hydrogen-donor potential when
photolysis was carried out by means of this technique.
Therefore, the nature of the solvent (i.e., aerosol organic
composition) will play an important role in the photoly-
sis of the compounds associated with particles.
Cl-Py
Py
R2 = 0.956
0
0.02
0.04
0.06
[Cl-Py], mM
0
20
40
60
80
100
3.3. Influence of a radical sensitizer
Time (min)
Reactive oxy-PAHs with an (np*) triplet state config-
uration are known to efficiently abstract hydrogen from
donors, and hydrogen abstraction is followed by further
reaction (Eqs. (1) and (2), where ArCO denotes an oxy-
PAH) (Feilberg and Nielsen, 2000).
Fig. 3. Decay of Cl-Py in the presence of AQ (5mM) and the
formation of Py during the photolysis (main panel), and the
relation between the concentrations of Cl-Py and Py in toluene
(insert).
ꢃ
ꢃ
1
3
ArCO þ hm ! ArCO ! ArCO
ð1Þ
strong hydrogen donor, Cl-Py dechlorinated by the
irradiation would be expected to accept hydrogen ab-
stracted from toluene by excited state triplet AQ, result-
ing in the formation of Py.
ꢃ
Å
Å
3ArCO þ RH ! ArCOH þ R
! radical chain reactions
ð2Þ
The radical synthesizer anthraquinone (AQ) was found
to strongly accelerate the photodegradation of nitro-
PAHs as well as PAHs in an organic medium (Jang
and McDow, 1995; Feilberg and Nielsen, 2000; Feilberg
and Nielsen, 2001; Feilberg et al., 2002). In addition,
AQ is present in ambient particulate matter
(4.1 1.6ng/m3) (Rogge et al., 1993) and traffic soot
(4.4–24.3lg/km) (Nielsen et al., 1999). In previous
study, we found that the photolysis rate of 3-nitroben-
zanthrone (<0.1mM) using the photoreactor became a
maximum when 5.0mM AQ was added to the solvent
(Feilberg et al., 2002). As a part of this study, we irra-
diated Cl-Py in toluene in the presence of AQ (5.0mM).
The photolysis proceeded by a first-order reaction
(Fig. 2). The rate constant in the presence of AQ was
about two times as high as that in the absence of AQ
(Table 1), which indicates that addition of a radical sen-
sitizer affects the photolysis rate of Cl-Py. This result
suggests the possibility that a radical chain reaction ini-
tiated through hydrogen abstraction from the solvent
by AQ could be responsible for Cl-Py decay. Here, it
is interesting to note that small amounts of Py, formed
by dechlorination of Cl-Py, were observed to build up
over time (Fig. 3). The relation between the decay of
Cl-Py and the formation of Py showed significant cor-
relation (R2 = 0.956, p < 0.01), which indicates that
the reaction steps from the excited state Cl-Py to Py
proceeded rapidly (insert, Fig. 3). Because toluene is a
3.4. Radical formation
For the decay process in actual environments, radical
reactions are important and perhaps dominating. The
possibility of radical formation under the experiment
conditions can be revealed from the identification of
the hydrogen abstraction compounds of the solvent.
That is, formation of bibenzyl (1,2-diphenylethane) can
be used as an indicator because bibenzyl is a byproduct
of hydrogen abstraction from toluene (Jang and
McDow, 1995). In Fig. 4, the ratio of integrated bibe-
nzyl area to internal standard area (i.e., relative bibenzyl
concentration) is plotted against irradiation time of Cl-
Py in the presence (5mM) and absence of AQ. Bibenzyl
was not analyzed in the first experiment. The rates of
bibenzyl formation in the presence and absence of AQ
were considerably different, which indicates that AQ
readily abstracted hydrogen from toluene. These facts
support our hypothesis about the production mecha-
nism of Py as a photolysis product in the presence of
AQ. In addition, the variation in bibenzyl formation
rates in the presence and absence of AQ is significantly
greater than the variation in the corresponding Cl-Py
decay rates. This fact may be due to the complex nature
of the degradation mechanism and to the indirect effect
of AQ, which has an ‘‘inner filter’’ (light-absorbing) ef-
fect (Feilberg et al., 2002).

836
T. Ohura et al. / Chemosphere 57 (2004) 831–837
Acknowledgments
7
6
5
4
3
2
1
The authors are most grateful to Dr. Anders Feilberg
and Dr. Torben Nielsen, Risø National Laboratory
(Denmark), for their guidance of the photolysis studies.
This work was supported by a Grant-in-Aid for Young
Scientists (B) (14780416) from the Japan Society for the
Promotion of Science.
AQ 5mM
AQ 0mM
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The photostability of Cl-Py was investigated in an or-
ganic solvent that simulates airborne particle surfaces.
The decay exhibited first-order kinetics, and the rate
constant was greater than that of Py, the parent com-
pound. Addition of a radical sensitizer, AQ, accelerated
the photolysis of Cl-Py. The mechanism of the forma-
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