Sources, deposition flux and carcinogenic potential of PM2.5-bound polycyclic aromatic hydrocarbons in the coastal zone of the Baltic Sea (Gdynia, Poland)

Abstract

Concentrations of 16 PAHs of different molecular weight and carcinogenic potency were measured in PM2.5 aerosols collected in the coastal zone of southern Baltic Sea (Gdynia, Poland) during the end of the heating and beginning of the non-heating season of 2012. Obtained results showed that coal combustion (pyrogenic source) contributed to the highest emission of PAHs during the heating season. However, similar concentrations of highly carcinogenic PAHs were detected in the non-heating period. The analysis of prevailing wind directions, air mass trajectories and diagnostic PAH ratios revealed that in addition to land transport emission (mainly from diesel vehicles), the increase in sea shipping traffic during the non-heating season contributed to the high concentrations of detected carcinogenic PAHs. We conclude that the increasing maritime activity in the southern Baltic Sea region might have an adverse effect on both environmental and human health. Therefore, it should receive more attention by the Polish government as a pollutant source.

Full text

Sources, deposition flux and carcinogenic potential of PM2.5-bound
polycyclic aromatic hydrocarbons in the coastal zone of the Baltic Sea
(Gdynia, Poland)
Karolina Skalska
1
&Anita Urszula Lewandowska
2
&Marta Staniszewska
2
&Andrzej Reindl
2
&Agnieszka Witkowska
2
&
Lucyna Falkowska
2
Received: 12 May 2019 /Accepted: 20 August 2019
#The Author(s) 2019
Abstract
Concentrations of 16 PAHs of different molecular weight and carcinogenic potency were measured in PM2.5 aerosols collected
in the coastal zone of southern Baltic Sea (Gdynia, Poland) during the end of the heating and beginning of the non-heating season
of 2012. Obtained results showed that coal combustion (pyrogenic source) contributed to the highest emission of PAHs during the
heating season. However, similar concentrations of highly carcinogenic PAHs were detected in the non-heating period. The
analysis of prevailing wind directions, air mass trajectories and diagnostic PAH ratios revealed that in addition to land transport
emission (mainly from diesel vehicles), the increase in sea shipping traffic during the non-heating season contributed to the high
concentrations of detected carcinogenic PAHs. We conclude that the increasing maritime activity in the southern Baltic Sea
region might have an adverse effect on both environmental and human health. Therefore, it should receive more attention by the
Polish government as a pollutant source.
Keywords PM2.5 .PAH s .Diagnostic ratios .Deposition flux .BaP-TEQ
Introduction
Polycyclic Aromatic Hydrocarbons (PAHs) are a group of
organic compounds composed of more than one aromatic
ring. They are typically classified according to their mass,
with the division into low (2-3 benzene rings), medium (4
benzene rings) and high (5-6 benzene rings) molecular weight
compounds being the most common (Ravindra et al. 2008).
PAHs’molecular weight and chemical structure determine
their characteristics. Lighter compounds are volatile and pri-
marily present in gaseous phase. Hence, they are widely dis-
persed in the atmosphere and can be washed out by rain
(Karali et al. 2018). Heavier compounds, on the other hand,
are characterised by a higher affinity towards solid phase and
can get readily adsorbed on particulate matter, which increases
their persistence in the environment. The latter have been of
major scientific interest due to their well-documented carcino-
genicity, genotoxicity and potential for DNA damage
(Błaszczyk and Mielżyńska-Švach 2016). It has been reported
that over 95% of particle-phase PAHs are associated with
particulate matter of less than 3 μm in diameter. Such aerosols
can easily penetrate the human respiratory tract, and, in the
case of sub-micron particulates, enter the blood stream. That,
in turn, leads to PAH-initiated carcinogenesis via the forma-
tion of PAH-DNA adducts (Liu et al. 2015).
Although PAHs are often associated with anthropogenic
emission (e.g. burning of coal or gas), they can also originate
from natural sources, such as forest fires or volcanic eruptions.
Anthropogenic sources include combustion processes (pyro-
genic PAHs) and maturation of crude oil (petrogenic PAHs)
(Ravindra et al. 2008). Because these processes result in an
emission of specific PAHs, individual sources can be distin-
guished using the diagnostic ratio method (Tobiszewski and
Namiesnik 2012). Irrelevant of the source, PAHs are always
emitted as a mixture rather than individual compounds
(Ravindra et al. 2008). The diagnostic ratio method uses the
relative concentrations of PAH pairs of the same molecular
weight and properties (isomers), which are thought to represent
specific emission sources (e.g. petroleum combustion or fuel
*Anita Urszula Lewandowska
a.lewandowska@ug.edu.pl
1
School of Environment and Technology, University of Brighton,
Brighton BN2 4GJ, UK
2
Institute of Oceanography, University of Gdansk, Al. Marszałka J.
Piłsudskiego 46, 81-378 Gdynia, Poland
https://doi.org/10.1007/s11869-019-00741-5
Air Quality, Atmosphere & Health (2019) 12:1291–1301
/Published online: 5 September 2019
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burning). A total of 16 priority PAH species, nevertheless, the
isomer ratio method has been widely used to determine sources
of PAHs in a range of different matrices, e.g. air, water, soil or
marine organisms (Tobiszewski and Namiesnik 2012).
High concentrations of PAHs are commonly noted in urban
regions, where they originate from burning fossil fuels, vehi-
cle combustion engines, as well as from the industrial sector.
Whereas west European countries are converting to green en-
ergy sources, eastern nations (i.e. Bulgaria, Poland,
Czech Republic, Slovakia) still rely on fossil fuel combustion
to generate electricity and heat (Garrido et al. 2014). As a
consequence, PAH levels in well-developed western
European countries rarely exceed the set threshold values,
while their elevated concentrations are frequently noted in
Eastern Europe (EEA 2018). Of all European countries,
Poland is often referred to as ‘Europe’s capital of smog’.
With air contamination showing no signs of improvement
and the current government’s ongoing investments in coal
mining, it remains one of the most polluted countries in
Europe. According to European Environment Agency,
Poland currently has the highest levels of BaP relative to other
European countries, with 87% of the total PAH emission
resulting from domestic coal and wood burning (EEA 2018).
High concentrations of BaP (in PM10) are routinely detected
all over Poland; however, its highest levels (as high as 22.7 ng
m
3
in 2017) are often noted in central and southern parts of the
country (Iwanek et al. 2016), partially due to the local topog-
raphy. Southern Poland is dominated by mountainous terrains,
which results in the trapping of contaminants in adjacent air.
Its northern part, on the other hand, is located near the Baltic
Sea, which facilitates an effective dispersal of air pollutants
(Lewandowska et al. 2018a). Air pollution is often associated
with rural areas, as a result of using low-quality coal and
outdated furnaces for heat generation in individual house-
holds. The practice of burning garbage (e.g. plastic bottles or
car tires) instead of coal in efforts to save money is also well-
documented (Lewandowska et al. 2018b). Due to domestic
heating being a large contributor to air pollution, seasonal
variability in PAHs concentration has beenreported by several
authors in Poland, with elevated levels of contaminants in the
autumn/winter period (e.g. Ćwiklak et al. 2009;Iwaneketal.
2016; Lewandowska et al. 2018b). Another potential source
of PAHs is the emission of exhaust gases and particulates from
diesel engines. It is well-acknowledged that diesel engines
contribute to the emission of both semi-volatile and particle-
bound hydrocarbons (Yilmaz and Davis 2016). An average
Polish car has been reported to be 13 years old, suggest-
ing that Poland has the oldest vehicles in European Union
(ACEA 2017).
With that many sources significantly contributing to the
problem of air pollution, it is vital to monitor the levels of
PAHs in the air and recognise their sources of origin to drive
measures to reduce their emission. This is especially important
for contaminants associated with smaller particles, which have
been found to be hazardous to human health (Liu et al. 2015).
Therefore, the purpose of this study was to assess the variabil-
ity of PM2.5-bound PAHs concentration in the late heating
andtheearlynon-heatingperiod(April-Mayof2012)in
Gdynia, located in the coastal zone of the southern Baltic
Sea. Thorough analysis of air mass trajectories and quantifi-
cation of PAH diagnostic ratios allowed identification of po-
tential sources of PAHs in the collected aerosol samples.
Moreover, an effort was made to estimate the deposition
fluxes and the overall carcinogenic potential of 16 priority
PAHs emitted over the analysed period.
Materials and methods
Sampling site
Aerosol sampling was conducted in Gdynia, Poland (Fig. 1).
Located on the southern coast of the Baltic Sea, Gdynia is part
of the urbanised area named the Tri-city,along with Sopot and
Gdansk (Lewandowska et al. 2018a). It currently has a popula-
tion of approximately 250,000. PM2.5 aerosols were collected
using a sampling device located on the roof of the Institute of
Oceanography (University of Gdansk; 54.51° N; 18.54° E),
about 560 m from the seashore. The sampling point was posi-
tioned at 20 m a.s.l., in close proximity to the busy roads of the
city centre, as well as the local seaport, the Gdansk Shipyard
and a bypass with high daily traffic including freight-hauling
trucks (approx. 3 km and 6 km away, respectively). Other air
pollution sources in the Gdynia region include domestic
heating, maritime activity and agriculture (Witkowska and
Lewandowska 2016;Lewandowskaetal.2018a).
Sample processing and chemical analysis of PAHs
PM2.5 samples were collected throughout April and
May 2012 (April 16, 2012–May 15, 2012) using FAI Hydra
Dual Sampler operating at a flow rate of 2.3 m
3
h
−1
.
Particulate matter was collected on QMA Whatman quartz
filters (φ= 47 mm). Prior to aerosol sampling, all filters were
pre-combusted in a muffle furnace for at least 6 h at 550 °C
and weighed (10
−5
gprecision,T= 23 ± 2 °C and air humidity
of 40 ± 5%). After sample collection, filters were weighed
again and kept in a desiccator under the same conditions as
before sampling. The mass of collected particulate matter was
determined by subtracting the pre-sampling mass of the filter
from its post-sampling total weight. This value was later di-
vided by the volume of air that passed through the sampling
device, enabling a precise quantification of PM2.5 concentra-
tion in a parcel of air. The limit of detection was estimated at
0.17 μgm
−3
, and the estimated error quantified for 28 blank
Air Qual Atmos Health (2019) 12:1291–1301
1292
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samples (p= 0.99) was around 4.1% (Witkowska and
Lewandowska 2016; Lewandowska et al. 2018a).
Prior to the analysis, a portion (φ=2.5cm)ofthe
filter was cut out. Sixteen priority PAHs were extracted
using the Soxhlet apparatus and a 1:1 mixture of tolu-
ene and methanol (250 cm
3
) as solvent. The extraction
was conducted over 8 h, with a frequency of 6–8cycles
per hour. Solvents were later evaporated from the ex-
tracts using a rotary evaporator, and the obtained liquid
was purified by solid-phase extraction using Florisil
magnesium silica cartridges (ThermoScientificHyperSep). At
this stage, the 1:1 mixture of toluene and methanol was
used as eluent. The obtained eluate was concentrated to
1cm
3
using a nitrogen evaporative concentrator. All of
the samples were analysed using the Agilent 1200 Series
HPLC System with a diode array detector. A solution of
acetonitrile and Merck MilliQ water (8:2) was used as
liquid phase, and the analytes were subsequently separat-
ed using Hypersil Green columns. A total of 16 priority
PAH species were analysed (identified according to the
obtained spectra and retention time): naphthalene (NAP),
acenaphthylene (ACY), acenaphthene (ACE), fluorene
(FLU), phenanthrene (PHE), anthracene (ANT), fluoran-
thene (FLA), pyrene (PYR), benzo(a)anthracene (BaA),
chrysene (CHR), benzo(b)fluoranthene (BbF),
benzo(k)fluoranthene (BkF), benzo(a)pyrene (BaP),
indeno(1,2,3-c,d)pyrene (IcdP), dibenzo(a,h)anthracene
(DahA) and benzo(g,h,i)perylene (BghiP). The limit of
detection was quantified at 0.001 pg cm
−3
(FLA) to
0.05 pg cm
−3
(NAP), whereas the average recovery was
estimated to be between 87 and 93%.
Weather conditions and air-mass back trajectories
Meteorological data has been collected throughout the entire
sampling period using the Vaisala MILOS 500 weather sta-
tion. Several variables were taken into consideration, includ-
ing wind velocity and direction, air temperature and relative
humidity, as well as the volume of precipitation. Basic statis-
tics acquired are shown in Table 1. Wind roses were generated
for both the heating and non-heating season.
Additionally, 48-h air mass back trajectories were com-
puted using the NOAA HYSPLIT Model (Stein et al. 2015)
for each day, using 6-h intervals and arrival heights of 500,
1000 and 1500 m. Where trajectories were found to differ
significantly, additional maps were created using the arrival
height of the sampling location and 3-h time intervals. The
method used was described in detail by Witkowska and
Lewandowska (2016).
Data analysis
Statistical calculations of average, maximum and minimum
values as well as standard deviations were made using the
STATISTICA®, R and EXCEL® software, which was also
used for the determination oflinear regression coefficients, the
standardisation of data and the graphic presentation of results.
In order to determine statistically significant differences in
more than two sets of independent and nonparametric data,
the Kruskal-Wallis test was used. For all dependencies pre-
sented in the publication, the level of significance (p) was
established at less than 0.05.
Fig. 1 Location of the sampling site (Gdynia, Poland)
Air Qual Atmos Health (2019) 12:1291–1301 1293
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Quantification of dry deposition flux
TheequationproposedbySeinfeldandPandis(2016) was used
to calculate the dry deposition flux of PM2.5-bound PAHs:
Ia¼VdC;ð1Þ
where I
a
corresponds to the dry deposition flux of aerosols [g
m
−2
s
−1
], V
d
—deposition velocity of aerosols [m s
−1
]andC—
concentration of aerosols, or the adsorbed pollutant [g m
−3
].
Based on the value estimated by Rodhe et al. (1980), the depo-
sition velocity of PM2.5 aerosols was assumed to be roughly
0.005 m s
−1
.
Quantification of BaP-equivalent
The Benzo(a)Pyrene Equivalent (BaPE) is a parameter com-
monly used to assess the relative human health risk associated
with exposure to carcinogenic PAHs. It is quantified based on
the average measured concentrations of PAHs characterised
by a high carcinogenic/mutagenic potential (Ladji et al. 2014).
The following equation was used:
BaPE ¼0:06 BaA þ0:07 BF þBaP þ0:6
DahA þ0:06 IcdP:ð2Þ
Results and discussion
Variations of PM2.5 concentrations in the atmosphere
over Gdynia
The average daily mass concentration of PM2.5 aerosols ob-
tained in Gdynia in the study period (April 16, 2012–May 15,
2012) was 37.37 μgm
−3
. This is in agreement with concen-
trations previously reported for the Tri-city at this time of year
(e.g. 33.02 μgm
−3
for October 2009–March 2010 reported by
Rogula-Kozłowska and coauthors (Rogula-Kozłowska et al.
2014), as well as for other European cities (Eeftens et al.
2013). Although PM2.5 levels were not monitored in
Gdynia during the investigated period, much lower concentra-
tions were noted in Gdansk (11.50 μgm
−3
, average calculated
for the same period), located 16 km from the study area.
Concentrations of PM2.5 reported by the Chief Inspectorate
of Environmental Protection were also much lower at other
Tri-city stations (average of 16.05 μgm
−3
) (2012 archived
data, http://powietrze.gios.gov.pl/pjp/archives). This was
unusual, as elevated PM2.5 levels are predominantly noted
in southern Poland due to domestic heating and the
excessive use of fossil fuels, especially coal (Rogula-
Kozłowska et al. 2014). For instance, Styszko and co-
authors (Styszko et al. 2017) reported PM2.5 concentrations
as high as 84.1 μgm
−3
in Poland’s second largest city,
Table 1 Meteorological data obtained in Gdynia throughout 16/04/2012-15/05/2012
Heating period (16-29/04/2012)
Non-heating period (30/04-15/05/2012)
Average
Min
Max
Average
Min
Max
Ta[°C]
11.3
0.2
23.7
13.5
1.6
31.4
Rhb[%]
48.7
10.0
90.0
43.0
10.0
87.0
Vwc[m·s-1]
2.6
0.0
9.8
2.6
0.0
8.7
Rainfall
[mm]
19
0.0
6.0
14
0.0
7.0
Wind
advection
[%]
75% land
25% sea
50% land
50% sea
Prevailing
wind
direction
and wind
speed
T, air temperature; Vw, wind velocity; Rh, relative humidity
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Krakow (Malopolska Voivodeship, SE Poland). It is possible
that the relatively high PM2.5 levels noted in Gdynia resulted
from the station being situated right next to a busy street. This
could have caused a higher load of particulate matter received
by the sampler. In addition, repair works were being under-
taken at a street situated near the study location, potentially
causing an increase in PM2.5 concentrations. Nevertheless,
the impact of domestic heating was largely pronounced, with
the average mass concentration of PM2.5 in the heating period
being significantly higher (41.70 μgm
−3
) than the one mea-
sured in the non-heating season (34.85 μgm
−3
), as confirmed
by the Kruskal-Wallis ANOVA test (p= 0.0124). The maxi-
mum average daily value (51.70 μgm
−3
) was observed during
the non-heating period (Table 2), which was most likely the
result of heating still taking place in individual households.
Indeed, air temperatures were only slightly higher in the non-
heating season compared to the period of active heating, with
minimum values of 1.6 °C and 0.2 °C, respectively. Moreover,
the natural emission of aerosols due to the re-awakening of
plant vegetation on land and in the sea could have contributed
to the elevated PM2.5 concentrations in the non-heating peri-
od (Hoyle et al. 2011). The maximum temperature in April
was 23.7 °C, and a high of 31.4 °C was reported in May
(Table 1), which could have facilitated the oxidation of volatile
organic compounds (VOCs) and subsequent generation of sec-
ondary organic aerosols (SOAs) (Sánchez de la Campa et al.
2009). With the average wind speed of 2.6 m s
−1
,itislikelythat
the regional source of aerosols prevailed during both, heating
and non-heating periods (Lewandowska et al. 2018a). The low
wind speed combined with the dominant wind direction from
the south west might suggest that aerosols were advected from
the Kashubian region, where low temperatures (relative to
Gdynia) are reported during early spring and individual heating
systems are prevalent. That, in turn, typically results in an in-
creased emission of air pollutants. Moreover, the relatively low
precipitation in the heating period could have prevented the
wash-out of particulates from the air.
Changes in PAHs concentration in PM2.5
in the atmosphere over Gdynia
It is well-established that particulate-bound PAHs display
strong seasonal variations due to the presence or absence of
combustion sources. Indeed, the mean ∑PAH
16
concentration
obtained in the non-heating season (9.40 ng m
−3
) was slightly
lower than that quantified for the heating period (12.56 ng
m
−3
)(Table2). These values are comparable to these reported
by Martellini and co-authors (Martellini et al. 2012), who
found PM2.5-bound ∑PAH
16
concentrations to range be-
tween 0.76 and 17 (winter) to 0.46 and 10 ng m
−3
(summer)
at an urban location in Italy (Florence, Tuscany). Much lower
concentrations are reported for warmer regions of Europe that
rely on coal and biomass combustion to a much lower extent
(e.g. ∑PAH
27
levels of less than 5 ngm
−3
were measured in
winter months in Athens by Alves et al. 2017). At the same
time, concentrations found in Gdynia were significantly lower
Table 2 Mass concentrations of PM2.5 [μgm
−3
]andPAHs[ngm
−3
]
obtained in Gdynia throughout April 16–May 15, 2012
Compound Heating period
(April 16–April 29,
2012)
Non-heating period
(April 30–May 15,
2012)
PM2.5 34.85 ± 6.91
(26.30–48.70)
41.7 ± 7.40
(28.80–51.70)
LMW Naphtalene 3.89 ± 3.71
(0.15–10.27)
0.24 ± 0.12
(0.15–0.32)
Acenaphtylene 5.96 ± 4.23
(1.02–11.70)
2.42 ± 1.31
(0.70–3.77)
Acenaphtalene 0.53 ± 0.42
(0.18–1.50)
0.30 ± 0.19
(0.12–0.56)
Fluorene 0.26 ± 0.21
(0.03–0.65)
0.06 ± 0.1
(0.01–0.27)
Phenantrene 0.08 ± 0.05
(0.02–0.15)
0.04 ± 0.03
(0.01–0.07)
Anthracene 1.05 ± 1.43
(0.15–5.04)
1.26 ± 0.68
(0.17–1.90)
∑LMW 7.94 ± 6.64
(1.14–19.58)
2.83 ± 1.92
(0.43–5.77)
MMW Fluoranthene 0.45 ± 0.26
(0.07–0.86)
0.23 ± 0.15
(0.11–0.53)
Pyrene 0.19 ± 0.18
(0.01–0.55)
0.04 ± 0.04
(0.01–0.08)
Benzo
(a)anthracene
0.15 ± 0.14
(0.01–0.39)
0.18 ± 0.19
(0.01–0.46)
Chrysene 0.22 ± 0.19
(0.02–0.39)
0.11*
∑MMW 0.65 ± 0.50
(0.07–1.87)
0.42 ± 0.33
(0.02–0.99)
HMW Benzo
(b)fluoranthene
0.40 ± 0.59
(0.03–1.85)
0.12 ± 0.10
(0.02–0.32)
Benzo
(k)fluoranthene
0.39 ± 0.49
(0.01–1.57)
0.33 ± 0.48
(0.01–1.27)
Benzo
(a)pyrene
0.23 ± 0.13
(0.04–0.41)
0.08–0.1
(0.01–0.23)
Dibenzo
(a,h)anthracene
0.87 ± 0.87
(0.08–2.09)
0.03*
Benzo
(g,h,i)perylene
8.25 ± 7.90
(1.35–17.40)
3.27 ± 2.15
(1.00–6.23)
Indeno
(1,2,3-c,d)pyrene
0.55* 5.09 ± 1.78
(2.97–6.90)
∑HMW 3.97 ± 5.76
(0.37–18.87)
6.16 ± 4.27
(1.13–13.37)
∑PAH
16
12.56 ± 7.88
(2.53–25.36)
9.40 ± 4.64
(4.50–17.49)
LMW, low molecular weight PAHs; MMW, medium molecular weight
PAHs; HMW, high molecular weight PAHs
*Single value obtained during sampling (the rest was below the detection
limit)
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than in highly urbanised polluted areas, where PAH levels can
be higher even by an order of magnitude. Mikuska and co-
authors (Mikuska et al. 2015) reported ∑PAH
16
concentra-
tions in the range of 435–2316 ng m
−3
during a 6-day winter
smog episode in Ostrava (Czech Republic).
The dominant PAHs detected over the study period were
BghiP (mean of 8.25 and 3.27 ngm
−3
for the heating and non-
heating season, respectively) and ACE (mean of 5.96 and 2.42
ngm
−3
for the heating and non-heating season, respectively).
Both compounds displayed a pronounced seasonality. Slightly
lower were the levels of IcdP and NAP. The lowest average
concentrations were noted for PHE (mean of 0.08 and 0.04
ngm
−3
for the heating and non-heating season, respectively),
which is consistent with its partitioning behaviour: due to its
characteristics, PHE is mostly found in vapour phase
(Ravindra et al. 2008). Average concentrations of DahA and
BaP, compounds characterised by the high carcinogenicity,
were relatively low and exhibited a similar pattern of elevated
concentrations in the heating season (e.g. mean BaP concen-
trations of 0.23 and 0.08 ng m
−3
were obtained for the heating
and non-heating season).
Although seasonality in particle-bound PAH concentrations
is well described for urbanised regions (Liu et al. 2015; Akyuz
and Cabuk 2009), a small number of studies focus on medium-
sized coastal cities like Gdynia and aerosols of less than 2.5 μm
in diameter. Results obtained in Gdynia revealed that the aver-
age concentration of BaP (widely recognised as the representa-
tive PAH) was approximately three times higher during the
heating period relative to the non-heating period (0.23 and
0.08 ng m
−3
, respectively). This was most likely due to the
increased coal consumption in the investigated region
(Ravindra et al. 2008; Lewandowska et al. 2018b). A pro-
nounced summer-winter variation in PAH concentrations de-
tected in PM2.5 in the coastal zone (Hong Kong) was previ-
ouslyreportedbyGuoandco-authors(Guoetal.2003). The
mean ∑PAH
16
concentration obtained in the summer (4.87 ng
m
−3
) was one order of magnitude lower than that noted in the
winter months (41.75 ng m
−3
). The winter concentrations of
PAHs were much higher in Hong Kong compared to those in
Gdynia, which can be explained by the much larger population
of Hong Kong combined with extensive maritime activity.
Moreover, Guo et al. (2003) accounted for the entire winter
season. At the same time, they observed BaP seasonality similar
to the one seen in our data (winter levels approximately three
times higher than summer; a mean of 2.06 and 0.73 ng m
−3
in
winter and summer, respectively). Comparable values were lat-
er reported by Villar-Vidal and co-authors (Villar-Vidal et al.
2014), who found PM2.5-bound BaP concentrations in Spanish
coastalcitiestorangebetween0.05and0.88ngm
−3
.Other
PAHs detected in PM2.5 in Gdynia revealed a similar trend
with much higher concentrations noted during the heating pe-
riod (Table 2), further supporting the hypothesis about the neg-
ative impact of domestic energy consumption on air quality.
This phenomenon has previously been observed by several
authors (Tobiszewski and Namiesnik 2012; Garrido et al.
2014; Lewandowska et al. 2018b).
The sampling location was situated near an industrial part of
the city and was heavily influenced by residential heating.
However, the trajectory analysis suggested that the highly con-
taminated air masses were transported from the Silesian
Voivodeship in Southern Poland. Meteorological conditions
largely determine the behaviour of atmospheric pollutants, and
it is likely that the relatively low concentrations of PAHs detected
in samples collected in coastal zones are a result of the highly
efficient dispersal of contaminants (Lewandowska et al. 2018b).
Sources of PAHs
Major PAH source types can be differentiated by their species
composition profile (i.e., ‘fingerprint’), permitting initial
source type identification based on the ratio of individual
compounds within diagnostic pairs. It is important that species
paired for diagnostic ratio analysis have the same molecular
mass and properties and are subject to similar transport and
reaction processes in the atmosphere (Galarneau 2008;
Tobiszewski and Namiesnik 2012). In general, petrogenic
sources typically release lighter hydrocarbons, whereas com-
pounds of pyrogenic origin are characterised by a higher mo-
lecular mass (Ravindra et al. 2008).
Based on PAHs values obtained in Gdynia in the study pe-
riod (April 16, 2012–May 15, 2012) the FLA/(FLA + PYR)
diagnostic ratio was calculated, revealing that detected PAHs
originated from coal or wood combustion during both the
heating and non-heating season (0.76 and 0.77, respectively)
(DeLaTorre-Rocheetal.2009).ThehighmeanIcdP/(IcdP+
BghiP) ratio in the heating period (0.97) also pointed at the
prevalence of pyrogenic sources in the studied region (Yunker
et al. 2002;Ravindraetal.2008). This further supports the
previously stated hypothesis about domestic heating being the
dominant PAH source in the first half of the study.
In the non-heating season, the mean IcdP/(IcdP+BghiP)
ratio decreased twofold (0.40), which might suggest that the
dominant source of PAHs changed from coal combustion to a
petrogenic origin (Yunker et al. 2002; Hanedar et al. 2014).
This was likely caused by the sampler’s proximity to several
busy roads. The prevailing PAHs in the study period included
ACE, NAP, BghiP and IcdP (Table 2), the first two typically
emitted as a result of coal combustion (Tasdemir and Esen
2007), which could explain their elevated levels in the heating
season. Concentrations of both decreased in the beginning of
the non-heating period, whereas the dominant PAHs changed
to BghiP and IcdP, commonly used as proxies for diesel en-
gine emission (Yilmaz and Davis 2016). The lowest
IcdP/(IcdP+BghiP) ratio noted over the analysed period was
0.14 (April 30, 2012) and could have been associated with the
emission of PAHs from diesel engines (Yunker et al. 2002).
Air Qual Atmos Health (2019) 12:1291–1301
1296
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

Furthermore, hydrocarbons composed of three benzene rings
were dominant throughout the entire sampling period
(40.7%), with the percentage of highly carcinogenic 6-ring
substances being slightly lower (30%). Such elevated abun-
dances of 3- and 6-ring hydrocarbons have been found to be
representative of diesel engine emissions (Yunker et al. 2002),
which might suggest that the busy street located near the sam-
pling device might have been a source of PAHs during the
entire study, or that the prevalent winds blowing from the west
carried contaminants from the adjacent bypass (Witkowska
and Lewandowska 2016). Notably, a high (31%) percentage
of vehicles registered in Gdynia are equipped with diesel en-
gines that reportedly contribute to PAH pollution (https://bdl.
stat.gov.pl). The mean BaA/(BaA+Chr) value (0.55) seems to
further confirm the contribution of this source to the overall air
pollution in Gdynia (Akyuz and Cabuk 2009).
It is also likely that the change of dominant source from
pyrogenic into petrogenic was caused by maritime transport.
The Baltic Sea is characterised by a high marine traffic, with
80% of cruise ships being able to accommodate more than
3,000 people. Most cruises take up to 20 h and are especially
popular during warmer months. In this study, high concentra-
tions of IcdP and BghiP seem to have been associated with an
intensification of maritime activity in the port of Gdynia
(Stankiewicz et al. 2010). For example, low IcdP/(IcdP+
BghiP) ratios were noted for May 01–02, 2012 and May 06–
09, 2012 (0.47 and 0.36, respectively). Such a pronounced
trend was not obtained for ANT/(ANT+PHE), which did not
display weekday/weekend variations and remained low (mean
= 0.03) throughout the entire non-heating period, suggesting a
petrogenic origin of PAHs. In addition to passenger vessels,
the local port serves cargo and tank ships that, back in 2012,
used heavy fuel oil and possibly emitted large amounts of
HMW PAHs without a clear weekend schedule (Adams
et al. 2014). Starting 2015, the Baltic Sea has become an
Emissions Control Area and vessels now have to comply with
strict SO
x
emission limits (Jonson et al. 2019). Nevertheless, it
has been suggested that sea shipping might still be a signifi-
cant source of airborne pollutants in Gdynia (Lewandowska
et al. 2018a,b). Despite the new regulations, the increasing
shipping in the port of Gdynia can cause an adverse effect on
the environmental health of the particularly vulnerable, land-
locked Baltic Sea (Stankiewicz et al. 2010).
To further support the PAH source investigation, a pollu-
tion rose was generated (Fig. 2). The analysis revealed that
throughoutthe whole investigated period, PAHs predominant-
ly originated from domestic heating in the Kashubian region
and the port of Gdynia. Although diagnostic ratios suggested
that road traffic contributed to PAH emission, it is probably
coal combustion in the domestic sector and sea vessel activity
that had the greatest influence on the detected levels of PAHs.
Deposition flux of PM2.5 and associated PAHs
Once emitted, PAHs can be removed from the atmosphere via
two major pathways: (i) photodegradation or (ii) wet and dry
deposition. The latter have been found to be the most effective
for particulate-bound PAHs. As a consequence, PAHs tend to
accumulate in soil, as well as aquatic sediments (Ravindra
et al. 2008). This is especially important in the case of heavy
PAHs that bind to aerosols and undergo slow biodegradation
in the natural environment. Their deposition velocity depends
on the particle size and a range of meteorological parameters
(e.g. air temperature or humidity) (Fang et al. 2004). Because
of their high carcinogenic and mutagenic potential and the
apparent tendency to accumulate in animal and plant tissues,
it is crucial to assess the flux of PM 2.5-bound PAHs.
Fig. 2 Pollution rose showing the
relative contribution of different
sources (represented by wind
directions) to PAH pollution
throughout the investigated
period
Air Qual Atmos Health (2019) 12:1291–1301 1297
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The quantified dry deposition flux of PAHs displayed var-
iations over the analysed period (Fig. 3). The flux of medium
weight compounds did not reveal significant variations, which
were most likely the result of its less pronounced sorption/
desorption kinetics (Ravindra et al. 2008).
Conversely, temporal variations were much more pro-
nounced for PAHs of low and high molecular weight. The
average dry deposition flux was estimated at 528 ng m
−2
day
−1
. In general, the highest values were obtained for
HMW PAHs, followed by slightly lower numbers quantified
for LMW PAHs (792 and 698 ng m
−2
day
−1
,respectively).
The mean total daily flux of PAHs was estimated at 4923 ng
m
−2
day
−1
, which is comparable to the value reported by Terzi
and Samara (2005) for a coastal sampling point located in
Greece (3917 ng m
−2
day
−1
). Much higher values are often
noted for highly urbanised and industrial regions. For exam-
ple, Fang and co-authors (Fang et al. 2004) estimated dry
deposition fluxes of total PAHs to be as high as 58,500 ng
m
−2
day
−1
in the industrial area in Taiwan.
At the same time, the dry deposition flux was decreased two-
fold after the heating season ended (65 and 28 ng m
−2
·season
−1
,
for the heating and non-heating period), once again pointing at
the significance of domestic heating in the studied region. Sixty-
three percent of PAHs emitted during the heating period were of
low molecular weight, with only 32% HMW PAHs contributing
to the overall flux. In the non-heating season, however, the trend
reversed and HMW compounds dominated over the lighter hy-
drocarbons (66 and 30%, respectively). Although the relatively
high abundance of HMW PAHs in the non-heating season could
be explained by the continuing emission of PAHs in individual
households, the diagnostic ratios suggest that the 6-ring PAHs
were most likely emitted by transport, both land and marine.
Further, the analysis of air trajectories revealed that the high-
dry deposition flux values obtained for HMW PAHs
corresponded to air masses being delivered from the harbour area
(north and north-west). For example, a very high total daily flux
of PAHs (5841 ng m
−2
day
−1
)wasnotedonMay06–09, 2012,
which corresponded to wind advection from the seaport (Fig.
4a). The low IcdP/(IcdP+BghiP) ratio (0.36) confirmed that pol-
lutants most likely originated then from sea vessel emission
(Yunker et al. 2002). This particular weekend marked a bank
holiday and a subsequent increase in cruise ship activity, which
contributed to a higher emission of PAHs.
The highest total flux of ∑PAHs
16
was noted in the heating
period, on April 17–18, 2012. The FLA/(FLA + PYR) ratio of
0.78 suggested an existing pyrogenic source of airborne pol-
lutants (De La Torre-Roche et al. 2009). In this case, the anal-
ysis of air trajectories revealed that air masses were advected
from the local bypass, as well as the Kashubian region (W-
SW, Fig. 4b). This observation further confirmed the relatively
high contribution of domestic heating and road traffic to the
air quality of Gdynia.
The carcinogenic potential of PAHs based on the BaP
equivalent method
Over the analysed period, the average BaP equivalent concentra-
tion was estimated at 0.9 ng m
−3
. Similar values have previously
been found in Florence, Italy (0.79 ng m
−3
) (Martellini et al. 2012)
and Hamilton, Canada (0.84 ng m
−3
) (Anastasopoulos et al. 2012).
At the same time, much higher values have been reported in
Fig. 3 Variability of the total dry deposition PAH flux over the investigated period
Air Qual Atmos Health (2019) 12:1291–1301
1298
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industrial, densely populated and polluted regions such as
Guangzhou, China (max = 22.46 ng m
−3
)(Liuetal.2015).
The mean BaPE was significantly higher during the
heatingperiodrelativetothenon-heatingseason(0.81
and 0.48 ng m
−3
), again pointing at domestic heating
sources of PAHs contributing to the overall air quality
of Gdynia over the analysed period. On April 22, 2012
(Sunday) the carcinogenic potential reached 1.4 ng m
−3
as a result of elevated concentrations of highly muta-
genic DahA and BF detected in PM2.5 aerosols. This
peak was most likely to the prevailing southerly winds,
which could have caused an advection of contaminants
from the highly polluted Kashubian region or the local
bypass during weekend road traffic.
Conclusions
The average concentrations of PAHs detected in PM2.5 aero-
sols in Gdynia were found to be relatively low throughout the
whole study. PAH levels were generally higher during the
heating season. That was likely due to PAH emission associ-
ated with fossil fuel combustion for domestic heating (pyro-
genic sources). However, concentrations of highly carcino-
genic heavy hydrocarbons increased during the non-heating
season as a result of sea shipping in the Gulf of Gdansk
(petrogenic source). At the same time, it is possible that a large
portion of PAHs originated from diesel engine emissions.
Levels of hazardous compounds associated with small aero-
sols should be carefully monitored throughout the upcoming
Fig. 4 Air mass trajectories (http://ready.arl.noaa.gov/HYSPLIT.php)andwindrosesonaMay 06, 2012–May 09, 2012 and bApril 16–18, 2012 in
Gdynia
Air Qual Atmos Health (2019) 12:1291–1301 1299
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

years, so appropriate measures can be taken. Although domes-
tic heating and vehicle emission remain the main contributors
to air pollution in Poland, it is important to account for all of
the possible PAH sources. Obtained results suggest that in
coastal locations, maritime emission might be underestimated
and should receive more attention. This is especially crucial
given the ongoing rapid expansion of sea shipping on the
global scale and its increasing effect on air quality.
Open Access This article is distributed under the terms of the Creative
Commons Attribution 4.0 International License (http://
creativecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided you give appro-
priate credit to the original author(s) and the source, provide a link to the
Creative Commons license, and indicate if changes were made.
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