Computational Water, Energy, and Environmental Engineering, 2013, 2, 41-45
doi:10.4236/cweee.2013.22B007 Published Online April 2013 (
Copyright © 2013 SciRes. CWEEE
Effect of Ambient Temperat ure on PUF Passive Sam p lers
and PAHs Distribution in Puerto Rico
Nedim Vardar 1, Ziad Chemseddine1, Juan Santos2
1School of Engineering, Inter American University, Bayamon, PR, 00957
2Department of Natural Sci ence, Inter A merican Univer si ty, Bay am on, PR , 00 95 7
Received 2013
Pas sive sa mplin g for the moni tor ing of orga nic p ollu tants ( PAHs, PCBs , PB DEs) in a mbie nt air ha s rec eived i ncrea sed
attention in the last two decades. Ho wever, the accuracy of the concentration of organics obtained with passive samplers
under var ying e n viro nme ntal co nditi ons i s a s ubj ect of co ntr over sy. I n thi s st ud y, ef fect o f a mbie nt t empe rat ure o n pa s-
sive samplers was evaluated by using three different sampler configurations. Additionally, passive samplers with poly-
urethane disks (PUF) were applied throughout the Island for the determination of the airborne concentration of poly-
cyclic aromatic hydrocarbons (PAHs). The passive samplers were deployed in seven municipalities for three-month
periods in two different sampling campaigns, representing hurricane and non-hurricane seasons. Here we present pre-
liminary results obtained from those sampling campaigns. The total concentrations of 15 PAHs varied from 3.1 to 19.6
and from 5.5 to 38.5 ng/m3 for hur ricane and no n-hurricane seasons, respectively. Hurricane and non-hurricane season
concentrations of PAH were significantly different for the samples taken in the northern municipalities of the Island.
However, there was no significant difference in PAH concentrations between the hurricane and non-hurricane seasons
for the southern sites. Increased rainfall and high-relat ive hu midit y durin g the hur rica ne se ason had an in fluence on the
concentrations of PAHs derived by the passive PUF sampler.
Keywords: Passive Sampler ; PAH; Puerto Rico; Hurricane; P UF; A mbie nt Temperature
1. Introduction
Passive samplers with polyurethane disks (PUF) have
been widely used for the last decade in the measurement
of semi volatile organics (SOCs), in part because they are
easy to handle, operate independently for several months,
and are inexpensive. Knowledge of the sampling rate of
the device is necessary for an accurate conversion of the
sampled mass to an ambient concentration. However,
environmental conditions around the sampler influence
the sampling rate and the performance with which the
PUF sampler can be used. The reliability of passive sam-
pling techniques under varying environmental conditions
is therefore a subject of controversy. Envir onme ntal co n-
ditions that may affect the PUF sampler are wind speed,
temperature (T), atmospheric pressure, sunlight/UV-light
and humidity. T affects the compound specific molecular
diffusion coefficients (D) of the pollutants by increasing
D with T.
Polycyclic aromatic hydrocarbons (PAHs) are a natu-
ral component of most fossil fuels, and formed during the
incomplete combustion of these fuels, or other organic
substances. Some PAHs are manufactured as individual
compounds for research purposes. The che mical struc ture
of PAHs is comprised of two or more fused aromatic
rings made entirely from carbon and hydrogen. PAHs are
ubiquitous environmental pollutants and are formed from
bot h nat ur a l and a nt hr op o ge ni c so ur ce s. Altho u gh na t ur al
sources such as forest fires and volcanic eruptions con-
tribute to PAH formation, most PAHs in ambient air are
the result of man-made processes. PAHs pose severe
risks to human health and the environment due to their
toxicity, persistence, ability to travel long distances on
air and water currents [1-3]. Human exposure to these
compounds may result in a variety of adverse health ef-
fects including damage to the central nervous and repro-
ducti ve s ystems, d evel op ment of l ung ca ncer a nd ge netic
alterations. There are hundreds of PAH compounds in the
environment, but only 16 of them are included in the
priority polluta nts list of the U.S. environme nt protection
agency (USEPA) [4].
A number of studies have been conducted on the fate
of PAHs in atmosphere during the past three decades
[1-3, 5-9]. In most of these studies, a high-volume sam-
pling technique using filter and adsorbent has been ap-
plied. However, the use of passive sampling methods to
moni- tor airborne contaminants has greatly increased
Copyright © 2013 SciRes. CWE EE
over the past few years. Passive samplers can be dep-
loyed at loca- tions where it is difficult or impractical to
install and maintain Hi-Vol samplers. These devices are
simple and inexpensive and do not need field calibration,
electricity nor technica l personnel at t he sampli ng site. In
addition, they can be deployed in many locations con-
currently due to their low cost.
Puerto Rico is located in the Caribbean with mainly
north-easterl y trade winds. Due to its location, the Is land
enjoys a tropical climate and a lso experiences the Atlantic
hurricane season. In this study, effect of ambient tem-
perature on passive samplers and seasonal distribution of
PAHs were evaluated Characterization of the PAHs in
the ambient air has been studied for a long time in other
parts of the world. A vast number of publications are
available in the literature for both urban and rural areas
from developed and developing countries [1-3,5-7].
How-ever, only limited data on atmospheric PAHs had
been acquired for Puerto Rico, and to our knowledge,
this is the first study to compare PAH concentrations
spatially distr ibuted across the island.
2. Materials and Method
2.1. Sampling Locations
Puerto Rico is a tropical island located in the Caribbean
Sea with a population of around 4 million. It has 9100
km2 total area and is one of the most densely populated
islands in the world. PUF pa ssive air samplers consisting
of polyurethane foam disks of 14 cm diameter and 1.2
cm thickness housed in two stainless steel bowls were
dep lo yed i n Ba yamo n, C aye y, Caroli na, Gua ya ma, Manati,
San Sebastian, and Naguabo (Figure 1).
Two sampling campaigns were achieved in 2010 for
three-month periods except in Naguabo where sampling
took place for six motnhs. Sampling parameters for the
samples are summarized in Table 1. Sampling sites of
Cayey and Manati are considered as urban, medium den-
sity, and residential. Bayamon and Carolina is described
as urban, high-density residential/industrial area. Naguabo
site is characterized as low-density coastal/resident ial.
San Sebastian is located in west part of the Island and
Figure 1. Map of Puerto Rico showing sampling locations.
Table 1. Passive Sampling Campaign Parameters.
Campaign Start
Date End
Date Temp .
C) Rain
Seas on March 2010 June 2010 27.7 17.9
Hurric ane S eason June 2010 October 2010 28 .6 21.8
considered as urban, medium density, and residential.
Last, Guaya ma sampling site is situated in a coasta l/rural
The temperature in the south of the Island is usually a
few degrees higher than the north. Between winter and
summe r, t here is onl y a te mpe ra ture s wing o f aro und 3˚C
Rainfall tends to be evenly distributed throughout the
year, but doubles during the months from May to Octo-
ber, as falls fro m November to April, with a driest period
from January to April. The wind patterns across the is-
land are basically zonal, from east to west.
2.2. Analy tical Proc edu re s
Information for sample preparation, extraction and analysis
is given in detail elsewhere [8]. Briefly, each PUF was
Soxhlet extracted with a 20:80 dichloromethane (DCM):
petroleu m ether (PE) solution for 24 h. All samples were
spiked with PAHs surrogate standards prior to extraction.
Four deuterated PAHs were used as surrogate standard
and P yre ne -d10 for volumetric corrections. The recoveries
of the following surrogate standards were used to correct
the amounts of specific PAHs found in the samples:
Ace na p h t hen e -d10 for acenaphthene (ACE), acenaphthylene
(ACT) and fluorine (FLN), phenanthrene-d10 for phe-
nanthrene (PHE), anthracene (ANT), and fluoranthene
(FL), chrysene-d12 for pyrene (PY), benz(a) anthracene
(BaA) and chrysene (CHR), and perylene-d12 for benzo
(b) fluoranthe (B bF), benzo(k)fluoranthe (BkF), benzo (a)
pyrene (BaP), indeno (1,2cd) pyrene (IcdP), dibenz (a,h)
anthracene ( DahA), and benzo(ghi)perylene (BghiP). T he
average recoveries for surrogates in field samples were
79% ± 31% for acenaphthene-d10, 86% ± 13% for phe-
nanthrene-d10, 84% ± 28% for chrysene-d12, 80% ± 15%
for perylene-d12.
The analysis of the samples was performed using a
Varian 450-GC coupled to an ion trap mass spectrometer
Varian 240 MS. A Varian factor 4 capillary column (30
m, 0.25 mm, 0.25 µm) was used. The GC oven tempera-
ture was programmed from 60(held one minute) to
130 at 7 min-1, then raised to 200 at 5 min-1,
and finally increased from 260 to 320 at 6 min-1.
The injector temperature was maintained at 295. The
linearity in the response of the GC/MS system was eva-
luated with calibration standards, at five different levels
of concentration (0.012, 0.06, 0.3, 0.6 and 1.2 ng/mL).
The instrument was Auto tuned at the start of runs with
Copyright © 2013 SciRes. CWEEE
perfluorotributylamine (PFTBA). Individual PAHs were
identified b ased o n the rete ntio n times of target io n p eaks.
Internal standard calibration procedure was used for
quantif ying the identified compounds.
Field blanks, which accompanied samples to the sam-
pling site, were used to determine any contamination
during sample handling and preparation. Newly cleaned
PUFs were used as laboratory blanks. There was no sta-
tistically recognizable difference between field and la-
boratory blanks.
3. Results and Discussions
Passive sampling devices have been widely used for
more than a decade for the measurement of semi volatile
organics (SOCs) in air. PUF passive air sampler consists
of two stainless steel bowls and all parts of the sampler
are made from the stainless steel. In this study, twenty
four hour temperature changes inside the passive sampler
were characterized using HOBO pendant temperature
sensor. In addition to stainless steel sampler, two more
samplers, one consists of plastic bowls and another with
cupper bowls, were used to characterize the effect ma-
terial on the diurnal temperature changes inside the sam-
plers. Figure 2 shows the diurnal temperature changes
inside a stainless steel sampler. Temperature variation
inside and outside the sampler is shown with blue and
green lines, respectively. Temperatures inside the samp-
ler were significantly higher than outside temperatures
during the midday due to intense solar radiation. During
the early mornings and late afternoon hours no signifi-
cant temperature differences were observed between in-
side and outside of the sampler.
Figure 2. Temperature variation inside (blue line) and out-
side (green line) of a stainless steel sampler.
In order to minimize midday temperature differences
between inside and outside of the sampler, choices of other
feasible materials were investigated. Cupper and plastic
sampling bowls were used in constructing the passive
sampler. Figure 3 compares the diurnal temperature
changes among different samplers. It was expected that
the lowest temperature would be observed inside the
plastic passive sampler due to the lower conductivity of
plastic. Ho wever, as it can be seen from the Figure 3, the
highest temperature inside the samplers belongs to the
one made of plastic bowls. A further study is needed to
expla in this findi ng. Out o f these three samplers, stainless
steel sampler gave the lowes t internal te mpe ratures.
A network of passive sampling spatially distributed
throughout Puerto Rico including both urban and rural
areas were conducted. The present study presents the fir st
ambient air data for PAHs in Puerto Rico. Due to its lo-
cation, Puerto Rico enjoys a tropical climate and also
experiences the Atlantic hurricane season. Hurricane
sea son e xt end s fr om J une 1st to November 30th. T herefo re ,
sampl es ta ken in the fir st a nd seco nd sa mpling c ampa ign
were classified as non-hurricane and hurricane samples,
respectively. Higher PAH concentrations were obtained
in all sampling site s for the non-hurricane samples except
Cayey site. The total concentrations of 15 PAHs varied
from 3.1 to 19.6 and from 5.5 to 38.5 ng/m3 for hurricane
and non-hur ricane s easons, r espectively (Figure 4).
Increased rainfall and high water vapor content during
the hurricane season makes wet depo sition very efficient,
leading to a decreased atmospheric lifetime of PAHs for
the Island. Carolina site had the highest PAH concentra-
tions for both hurricane and non-hurricane season. Sea-
sonal concentration differences of PAH were more sig-
nific ant for the sa mples ta ken i n the no rthern municip ali-
ties (Bayamon, Manati, Carolina) than the southern mu-
nici pali ties (Caye y and Gua yama) of t he Isl and. T he nort h
Figure 3. Diurnal temperature changes among different
Copyright © 2013 SciRes. CWE EE
Figure 4 . Total P AH c once ntr a tions f or e ac h sa mpli ng l oca-
tions .
Table 2. At mospheric PAH Co ncentratio ns Derived by Pas-
sive Samplers in Different Stu dies.
Location Ran g e of Total
PAHs (ng/m3) Reference
Vario us M un icipal it ies, PR
Non-Hu r ricane S eason
Hurr ic ane Season
5.5 - 38.5
3.1 - 19.6 This study
Toronto, Canad a
16.5 - 61 .4
10.1 - 18 .5
3.53 - 18.8
Harbin, China
25 - 120
13 - 50
22 - 74
81 - 240
Taichung, Taiwan 387.70 [5]
Mexico City, Mexico 32 - 92 [6]
Athens, Philippines 28.44 [7]
coast of the Island gets twice as much rain as the south
coast. Thus, increased precipitation as well as high- rela-
tive humidity during might have an influence on the
concentrations of PAHs derived by the passive PUF
Table 2 provides a comparison of the ambient PAH
concentrations measured by passive samplers in different
part of the world. The PAH concentrations in the Island
are almost similar to those reported by [4] for winter and
spring seasons, but compared to summer season the Isl-
and concentrations are lower.
The PAH levels reported for Taichung, Taiwan are an
order of magnitude higher than those measured in this
study [14,15]. In Mexico, and Harpin, China, PAH con-
centrations significa ntly higher than the one measured in
this study [16]. In a study conducted in Athens, Philip-
pines, PAH concentrations were approximately twice
higher t han those measured in this st udy [17].
4. Conclusions
This study has provided some baseline data on the atmos-
pheric PAH levels in Puerto Rico which could be useful
for establishing long-ter m atmo spheric monitoring pr ogram
in the Island. In this study, the spatial characteristics of
PAHs derived from PUF passive sampler were studied
for two different sampling campaigns at the seven dif-
ferent sampling sites of the Island. It was found that
hurricane and non-hurricane season concentrations of
PAH were significantly different for the samples ta ken in
the northern municipalities of the Island. Ho wever, there
was no significant difference in PAH concentrations
between the hurricane and non-hurricane seasons for the
southern sites. Increased precipitation and high-relative
humidity during the hurricane season might have an
influence on the concentrations of PAHs derived by the
passive PUF sampler.
Diurnal temperature variations inside the passive sam-
plers constructed from stainless steel, cupper and plastic
sampling bowls were investigated. Sampler made of
stainless steel gave the lowest internal temperature s.
5. Acknowledgements
The authors would like to tank to the NSF -MRI program
for funding the purchase of the GC/MS/MS and to Puerto
Rico Louis Stokes Alliance for Minority Participation
(PR-LSAMP) for supporting this study.
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