Microplastic Particles in Sandy Beaches of Thessaloniki Gulf, Greece
TZIOGA IOANNA, MORIKI AMALIA
Department of Food Science and Technology,
International Hellenic University,
P.O BOX 141, 574 00 Thessaloniki,
GREECE
Abstract: - Microplastic pollution is a major issue for aquatic ecosystems. In this study, an assessment of
microplastic pollution in beach sediments of Thessaloniki Gulf is presented. Sand sampling was performed in
October 2021, in three different coastal areas along the seashore of Thessaloniki Gulf, in NW Aegean Sea. In
total, nine sand samples were collected and examined. The morphology of the detected microplastics was
recorded: they were fragments and microfibers. Their abundance ranged from 0-32 items/m3. Higher
concentrations of microplastics were observed in Karabournaki Beach, located in the city of Thessaloniki. It is
the second largest city in Greece, inhabited by about 1,5 million people. Regarding the color, black, red, blue,
green, and transparent microplastic fragments were found. Black and blue particles were the most common.
Chemical detection and identification were performed with FT-IR spectroscopy. Four polymers were detected:
polyethylene (PE), terephthalate (PET), high-density polyethylene (HDPE), polypropylene (PP), and
polytetrafluoroethylene (PTFE). Polyethylene terephthalate was the dominant identified polymer (50%). The
need for plastic pollution management in coastal areas, as well as the need to communicate the issue of plastic
marine pollution and enhance public awareness, are discussed.
Key-Words: -marine pollution; microplastics; sediments; FT-IR; coastal management, Thessaloniki Gulf.
Received: March 17, 2023. Revised: October 9, 2023. Accepted: December 12, 2023. Published: December 31, 2023.
1 Introduction
Microplastic pollution is a major environmental
problem as a result of the multiple uses of plastic in
modern societies. Microplastics (MPs) are a threat
to both marine organisms and human health since
their presence has become evident in most
ecosystems, [1]. The cumulative global production
of plastics in the 50’s was 1.5 million tons, while in
2020 reached 367 million tons, [2]. Μarine plastic
pollution affects ocean health, ecosystems,
biodiversity, wild animal conservation, and welfare,
[3]. The first records of plastic ingestion by
Canadian seabirds are from the early 1960s, [4], [5].
Microplastics are plastic pieces smaller than 5
mm [6]. Two types of microplastics are
contaminating the world’s ocean: primary and
secondary microplastics. Primary MPs are those that
enter the environment when their dimension is <5
mm, [7]. They are produced through industrial
production and are mainly used in personal care
products, creams, cosmetics, and other plastic
nanoparticles. Secondary microplastics result from
the fragmentation and weathering of larger plastic
items, [8].
Identification and quantification of
microplastics in the marine environment is a major
concern during the last decade, [9], [10], [11]. In the
present work, microplastic particle concentrations
were determined on three sandy beaches of
Thessaloniki Gulf. The study aimed to provide data
on microplastics' degradation in the beaches around
the metropolitan area of the city of Thessaloniki,
assess the abundance of microplastics in
Thessaloniki Gulf and identify the chemical
composition of the collected microplastic fragments.
2 Materials and Methods
2.1 Description of the Study Area
Three beaches located along the coastline (Figure 1)
of the Gulf of Thessaloniki (inner Thermaikos
Gulf), were selected for sampling, based on their
geographic location (Table 1). Thermaikos Gulf is a
semi-enclosed coastal basin, located in the northern
part of the Aegean Sea. Along the northern coast of
the gulf is located the city of Thessaloniki, the
second largest city in Greece inhabited by about 1.5
million people. Four rivers, Axios, Aliakmonas,
Loudias, and Gallikos, discharge in the gulf forming
an ecologically important deltaic environment, [12],
[13]. Various sources of pollution affect water and
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Tzioga Ioanna, Moriki Amalia
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sediment quality in the coastal zone: effluents from
the industrial zone of Thessaloniki, the wastewater
treatment plant of the city, agricultural runoff from
Thessaloniki’s rural areas as well as the activities in
the harbor of the city and plastics used in intensive
mussel farming, [14].
The coastal area of Aggelochori (Figure 2,
right) is located in the southeast part of the gulf.
Kalochori (Figure 2, in the middle) is located to the
west of Thessaloniki Gulf. The lagoon in this area is
part of the European Ecological Network of
NATURA 2000 Areas, a network of nature
protection zones in the territory of the European
Union. Karabournaki- Deauville beach (Figure 2,
left) is one of the beaches of the city in the suburb
Kalamaria. The beach is still used by some
swimmers.
Fig. 1: Sampling sites
Fig. 2: Photos of the sampling sites
2.2 Wind-driven Circulation of Waters
Coastal hydrodynamics in the area are affected
mostly by the wind. The circulation of waters is
characterized by the entrance of northeastern less
saline waters from the North Aegean and the Black
Sea, moving along the east shores to the west and
northwest of the gulf, [14].
2.3 Sampling
At each sampling area the "Guidance on Monitoring
of Marine Litter in European Seas" protocol was
used to collect and analyze sediment samples, [15].
A random grab sampling of beach sand for
microplastic separation was carried out on the 21st
of October 2021. On each beach, three random
sampling sites of 1 m2 each were chosen. A jar of
250 mL of sand was collected from every point,
using a stainless steel spatula. The filled jars were
placed in a dark and cool place, as soon as possible,
to prevent deterioration of the samples.
Separation of the lighter plastic particles from the
heavier sediment grains, was obtained by mixing a
portion of the sample (100 g) with a saturated
solution (concentrated saline NaCl solution 1.2 g
cm−3) and stirring for a certain period, [16], [17].
This method was chosen, among others, because it
is simple and environmentally friendly. The sample
was filtered through a 20 μm filter. The filter was
rinsed with deionized water to remove any salt.
During the analysis in the laboratory, researchers
wore lab coats and there was a filter wetted with
deionized water on the bench top, to study any
contamination of the laboratory environment.
Table 1. Geographical coordinations of the sampling
sites
Site
Longitude
Latitude
Kalohori (Axios
River Delta)
1
22.670807
40.526942
2
22.671766
40.527112
3
22.674461
40.527854
Aggelohori
(beach to the
eastern Gulf)
1
22.817236
40.498427
2
22.816932
40.498025
3
22,816502
40.497475
Thessaloniki-
Karabournaki
(Deauville
Beach)
1
40.588831
22.942297
2
40.588974
22.942789
3
40.589357
22.943632
2.4 Sample Characterization
After the separation, the samples were examined
under a stereomicroscope (SLX-3, OPTIKA,
magnification 10x), to identify the type of
microplastic items and record their color. The
samples were analyzed by FT-IR spectroscopy
method with a Jasco FT-IR 6700 spectrometer. In
each sample, spectrum was recorded three times in
the area of 4000-400 cm-1, after 64 scans and
baseline correction. This method provides a unique
spectrum for each type of polymer, it requires a
small sample quantity and provides great reliability,
[18]. Interpretation of the spectra was performed
with the aid of OpenSpecy software, [19].
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Fig. 3: Microplastic fragments of sediment samples
from the beach in Kalamaria
3 Results
3.1 Microplastic Observation and
Enumeration
A total of thirty-one microplastic particles, were
collected from the three beaches shown in Table 1.
Most of the items found in these samples were
fragments (55%) and microfibers (45%).
From Kalohori, close to the Axios river Delta,
two fragments and one microfiber were collected.
The size of the items was too small to conduct FT-
IR analysis. From the beach in Aggelochori, to the
east of Thessaloniki, two fragments were collected
and one of these was PET. From Karabournaki-
Deauville Beach in the suburb Kalamaria, twenty-
three items, thirteen fragments, and eleven
microfibers, were collected (Figure 3). The highest
percentage 70%, of microplastics were found in
Karabournaki, and the lowest, 9.6%, in the Axios
river Delta (Figure 4).
Fig. 4: Microplastics % in each sampling site
Fig. 5: Type of microplastics
Microplastic fragments and fibers were 54.8%
and 45.1% of the items, respectively. Most of the
fragments were blue (59%) followed by red color
(29%). Among the fibers black was the dominant
color (71%), followed by red (14%). Terephthalate
(PET) was the origin of 50% of the microplastics
(Figure 5). The second most abundant polymer was
high-density polyethylene and a smaller percentage
was polypropylene.
3.2 FT-IR Analysis
The fragments from all samples were analyzed by
FT-IR spectroscopy method. Figure 6 and Figure 7
show the beached IR spectra of HDPE and PET,
respectively. Characteristic PET peaks were at 2833
and 2851 cm−1 [16]. HDPE spectrum of the samples
peaks were at 2872 and 2950 cm−1, [20].
Fig. 6: Beached sample IR spectrum of PET
Fig. 7: Beached sample IR spectrum of HDPE
4 Discussion
Plastic fragments and microfibers were found on the
three beaches in Thessaloniki Gulf, made of PET
and HDPE. PET was identified as the prevailing
polymer in all three sampling locations, while on
Karabournaki Beach, most of the fragments
originated from HDPE. Plastic polymers can be
found in our daily life such as polyethylene
terephthalate in plastic bottles, polyethylene in
plastic bags, or polypropylene in food packaging
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and ropes. Polyethylene is an indispensable
commodity polymer widely used in the production
of synthetic packaging materials, [21]. This polymer
can be further classified as high-density and low-
density polyethylene (HDPE and LDPE). Samples
from Karabournaki Beach presented a greater
occurrence of microplastics, possibly due to
Thessaloniki’s high population and the proximity to
major urban sources. Since many of the micro and
nano plastics are dangerous for the environment and
human health, [22], more studies are necessary to
evaluate microplastic pollution in Thermaikos and
Thessaloniki Gulfs. Regulation of the urban
development in coastal environments is necessary
since the level of pollutants in coastal aquatic
habitats is of increased concern, [23], [24]. The
management of marine plastic pollution has many
aspects: starting from people’s perception of the
environmental risks of plastic use, to legislation and
decisions from the stakeholders and decision-
makers. Public awareness of the environmental
threat of microplastics is needed as well as
appropriate legislative and management actions for
plastic use and disposal in the oceans.
5 Conclusion
Polyethylene terephthalate (PET) was the dominant
identified polymer on Thessaloniki Gulf beaches, as
a result of plastic bottles carelessly disposed of in
the coastal zone and marine environment.
Management measures are required for marine litter
disposal.
Acknowledgement:
The authors want to express their appreciation to Dr.
Anastasia Kyriakoudi, post-graduate researcher in
the Laboratory of Food Chemistry and
Biochemistry, School of Agriculture, AUTh, for her
valuable contribution to FT-IR analysis.
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Contribution of Individual Authors to the
Creation of a Scientific Article (Ghostwriting
Policy)
- Ioanna Tzioga carried out the field and laboratory
work. She also prepared the initial draft.
- Amalia Moriki was responsible for organizing
research and contributed to editing and the final
manuscript.
Sources of Funding for Research Presented in a
Scientific Article or Scientific Article Itself
No funding was received for conducting this study.
Conflict of Interest
The authors have no conflicts of interest to declare.
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