Comparison of Radioactivity and Metal Pollution Concentrations in
Marine Sediment Samples Obtained from the Aegean Sea (Turkey) and
the Calabria Region (Italy)
SERPIL AKÖZCAN1, SIMONA MANCINI2, SELIN ÖZDEN1, VALENTINA VENUTI3,
FRANCESCO CARIDI3, GIUSEPPE PALADINI4, MICHELE GUIDA2
1Department of Physics, Faculty of Science and Literature,
Kirklareli University, Campus of Kayali, Kirklareli,
TURKEY
2Department of Information Engineering,
Electric Engineering and Applied Mathematics (DIEM), University of Salerno,
via Giovanni Paolo II, 84084 Fisciano (SA),
ITALY
3Dipartimento di Scienze Matematiche e Informatiche,
Scienze Fisiche e Scienze della Terra, Università degli Studi di Messina,
V.le F. Stagno D’Alcontres, 31-98166 Messina,
ITALY
4Dipartimento di Fisica e Astronomia “Ettore Majorana”,
Università degli Studi di Catania,
Via S. Sofia, 64-95123 Catania,
ITALY
Abstract: - Marine sediments are the basic reservoir for radionuclide and metal hold because of their diverse
composition. These sediments accumulate naturally occurring radionuclides such as 226Ra, 232Th, and 40K as
a result of scavenging and settling processes in the water column. The knowledge of the levels and
distributions of the radionuclides such as U, Th, and Ra and heavy metals have common environmental
concerns along with the health hazards to human beings, animals as well as the marine environment.
This study was to assess the concentrations of some heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn)
and three main natural radionuclides (226Ra, 232Th, and 40K) within the surface sediments collected from
Turkey (Aegean Sea) and Italy (Calabria region). Activity concentrations of natural radionuclides were
measured by High Purity Germanium (HPGe) gamma spectrometry. Heavy metal levels were determined by
inductively coupled plasma mass spectrometry (ICP-MS) in Italy and inductively coupled plasma optic
emission spectrometry (ICP-OES) in Türkiye. The activity concentrations 226Ra, 232Th, and 40K at Aegean
Sea region (Türkiye) ranged from 9± 1 Bq kg−1 dry weight (d.w.) to 60 ± 2 Bq kg−1 (d.w.) for 226Ra; from
6 ± 0.3 Bq kg−1(d.w.) to 64 ± 1 Bq kg−1 (d.w.) for 232Th; for 40K, 250 ± 13 Bq kg−1(d.w.) to 978 ± 6 Bq kg−1
(d.w.) and at Calabria region (Italy) ranged from 14 ± 1 Bq kg−1 dry weight (d.w.) to 54 ± 9 Bq kg−1 (d.w.)
for 226Ra; from 12 ± 1 Bq kg−1(d.w.) to 83 ± 8 Bq kg−1 (d.w.) for 232Th; for 40K, 470 ± 20 Bq kg−1(d.w.) to
1000 ± 70 Bq kg−1 (d.w.). The mean concentrations of Mn, Fe, Ni, Cu, Zn, Cr, Cd, and Pb were 197.6;
8139.3; 6.3; 6.0; 24.9; 10.5; 0.05 and 6.8 mg kg-1 (d.w.) in Italy and 187.0; 6993.5; 10.0; 14.3; 29.9; 21.7;
0.02 and 7.1 mg kg-1 (d.w.) in Turkey, respectively. From the measured specific activities, radium
equivalent activity, the absorbed dose rate, annual effective dose equivalent, and external hazard index due
to the natural radionuclides were calculated to assess the health risk. Radium equivalent activity was lower
than the world average for both Turkey and Italy. And also, the external hazard indices were found to be
below the hazard limit of unity.
Key-Words: - Gamma spectrometer, metal, radionuclide, sediment
Received: January 4, 2023. Revised: April 25, 2023. Accepted: May 27, 2023. Published: June 19, 2023.
WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT
DOI: 10.37394/232015.2023.19.57
Serpil Aközcan, Simona Mancini,
Selin Özden, Valentina Venuti,
Francesco Caridi, Giuseppe Paladini, Michele Guida
E-ISSN: 2224-3496
591
Volume 19, 2023
1 Introduction
The natural radiation level in a region varies with
cosmic radiation as well as with the presence of
naturally occurring radionuclides in the Earth's
crust, atmosphere, and water bodies, [1]. These exist
in various geological formations such as the earth's
crust, rocks, soils, plants, water, sediments, and air.
Humans are exposed to ionizing radiation from
natural radionuclides from the environment. The
main natural contributors to external exposure from
gamma rays are 226Ra, 232Th, and 40K, [2], [3].
Heavy metals are one of the main pollutants in
our environment and their high levels may indicate
the presence of anthropogenic pollutant sources, [4].
Heavy metal contamination in marine environments
is generally monitored by measuring concentration
in biota and sediment.
Determinations of the concentration of
radionuclides and metals in various objects of the
environment are now actively used to assess the
ecological state of regions. In the environment such
monitoring and assessment work is being actively
carried out for soil, seawater, sands, and sediments,
[5], [6]. Sediment in lakes, rivers, and the sea can be
a source of contamination of aquatic organisms. For
example, contaminated sedimentary materials used
as fertiliser can increase radioactivity levels in the
soil, which can reach humans through the food
chain. As sediments are one of the basic carriers of
heavy metals and radionuclides into the marine
ecosystem, it has a major role in monitoring heavy
metal and radionuclide pollution in the aquatic
environment, [7]. Many investigations have been
conducted worldwide to assess the activity
concentrations of NORMs in sediment. It is of great
importance for the assessment of the dose to the
population, which plays a vital role in the
investigation of health risks from radioactivity in
sediment and soil and will provide a baseline for
changes in environmental radioactivity due to
human activities.
The objective of this work however is to
determine the heavy metals (Fe, Mn, Zn, Cu, Ni, Pb,
Cr, Cd) and radioactivity levels of 226Ra, 232Th, and
40K in marine sediments from coastal areas of
Aegean Sea (Turkey) and Calabrian region (Italy)
and to evaluate the probable health risks associated
with them. The data will be useful as baseline data
to be used in subsequent studies for the areas
studied and also in carrying out any environmental
health surveillance.
2 Materials and Method
2.1 Sample Collection and Preparation
In Italy, marine sediment samples of about 1 kg
were collected in selected Ionian and Tyrrhenian
Calabrian locations, indicated in Figure 1(a).
In Turkey, marine sediment samples were
collected from the sites of Bodrum, Didim, Urla,
and Aliağa (Aegean Sea, Turkey) as shown in
Figure 1(b).
The same procedure for the sample preparation
was adopted. All of the samples were oven dried at
a temperature of 105oC and sieved through a 2 mm.
Then, the samples were put in a container and
completely stored for at least 4 weeks to achieve the
radiative balance of natural radionuclides and their
progenies.
2.2 Gamma Spectrometric Analysis
Specific activities of radionuclides in sediments
were measured using a coaxial HPGe detector in
multilayer shielding. Determination of counting
efficiency and calibration was done by using the
soid mixed source (containing radionuclides in the
energy range 80 to 2500 keV) provided by the
Isotope Product Laboratories. To acquire and
elaborate data, the Gamma Vision (Ortec) software
was employed.
The specific activity C (Bq kg-1 d.w.) of each
investigated radionuclide was assessed with the
following equation:
 (1)
where NE, ε, γ, M (kg), and t (s.) are the net area of a
photopeak at energy E, its efficiency, its yield, the
mass sample, and the lifetime, respectively.
2.3 Metal Analysis
The sediment sample (approximately, 1 g) was
dissolved with mixed acid (5 mL H2SO4, 3 mL
HNO3, 5 mL HF, 0.5 mL HClO4) in a Teflon
beaker, [8]. After that, the dissolved sample was to
100 mL with 2 % HNO3, and the concentrations of
heavy metal (Cd, Cr, Ni, Pb, Cu, Zn, Mn, and Fe)
were determined by ICP-OES at Türkiye.
The sediment sample (approximately, 0.5-0.7
g) was dissolved in mixed acid (3 mL of ultrapure
(67–69%) HNO3 and 9 mL of ultrapure (32–35%)
HCl) were directly introduced into the TFM vessel.
Acid digestion was performed using a Milestone
microwave unit system, Ethos touch control, in
three steps: 15 minutes at 1000W and 200 oC; 10
minutes at 700W and 200 oC; 10 minutes cooling,
WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT
DOI: 10.37394/232015.2023.19.57
Serpil Aközcan, Simona Mancini,
Selin Özden, Valentina Venuti,
Francesco Caridi, Giuseppe Paladini, Michele Guida
E-ISSN: 2224-3496
592
Volume 19, 2023
[9]. After cooling, vessel contents were filtered and
filled up to 50mL with distilled H2O. The final
sample was then diluted at a concentration of one
order of magnitude lower than the initial value.
The concentrations of heavy metals (Cd, Cr, Ni,
Pb, Cu, Zn, Mn, and Fe) were determined by a
Thermo Scientific iCAP Qc ICP-MS in Italy, [10].
Fig. 1: Location of the sampling site: (a) Italy and
(b) Turkey
2.4 Radiological Hazards
Following the measurement of the radionuclide
concentrations in the samples, the radium equivalent
activity (Raeq), the absorbed dose rate (D), the
annual effective dose equivalent (AEDE), and the
external hazard index (Hex) were used as
radiological indicators to estimate the radiological
implications of the use of the marine sediment
samples.
Raeq was calculated as the Eq. (2), [11], [12]:
    (2)
where CRa, CTh, and CK are the activity
concentrations of 226Ra, 232Th, and 40K, respectively.
The absorbed gamma dose rate in the air was
calculated using Eq. (3), [13], [14]:
D (nGy h-1) = 0.462 CR a+ 0.604 CTh+ 0.0417 CK
(3)
Where, CR a, CTh, and CK are the radioactivity
concentration in Bq kg−1.
The annual effective dose equivalent due to natural
radioactivity was calculated using Eq. (4).
AEDE (mSv y-1) = D (nGy h-1) x 8760 x 0.7 (Sv Gy-
1) x 0.2 x 10-6 (4)
Where 0.7 Sv Gy-1 is the conversion coefficient for
an absorbed dose in the air to an effective dose in
the human body and 0.2 is an outdoor occupancy
factor.
The external exposure to gamma rays in the study
region is called the external hazard index, or Hex.
This index is given by the following Eq. (5):
 
 

 (5)
where CRa, CTh, and CK are the radioactivity
concentration of 226Ra, 232Th, and 40K in Bq kg−1,
respectively.
3 Result and Discussion
The activity concentrations of 226Ra, 232Th, and 40K
in marine sediment samples from the Aegean Sea
(Turkey) and the Calabria region (Italy) are reported
in Table 1.
In the Aegean Sea, the mean activity
concentrations were found to be 21.50, 23.13, and
541.88 Bq kg-1, respectively. The concentrations of
the radionuclides in the Aegean Sea were higher in
Aliağa locations (A7 and A8) compared to the other
locations, [15]. In the Calabrian region, the mean
activity concentrations were found to be 26.63,
37.63, and 793.75 Bq kg-1, respectively and the
highest specific activity of 226Ra, 232Th, and 40K is
found at site I6 for all of them.
WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT
DOI: 10.37394/232015.2023.19.57
Serpil Aközcan, Simona Mancini,
Selin Özden, Valentina Venuti,
Francesco Caridi, Giuseppe Paladini, Michele Guida
E-ISSN: 2224-3496
593
Volume 19, 2023
Table 1. Gamma spectrometry results for the
analyzed samples
Sampling
Station Code
226Ra
Bq kg−1
(d.w.)
232Th
Bq kg−1
(d.w.)
Aegean
Sea
(Turkey)
A1
12±1
15±1
A2
10±1
15±1
A3
10±1
7±1
A4
9±1
6±0.3
A5
11±1
14±1
A6
15±1
16±1
A7
45±8
48±7
A8
60±2
64±1
Calabria
region
(Italy)
I1
14±1
25±3
I2
22±3
12±1
I3
22±2
26±2
I4
15±2
18±2
I5
26±5
40±4
I6
54±9
83±8
I7
42±4
70±6
I8
18±1
27±2
The worldwide average concentrations of the
radionuclides 226Ra, 232Th, and 40K reported by
UNSCEAR are 35, 30, and 400 Bq kg-1,
respectively. The results show that the mean activity
of 226Ra, 232Th, and 40K in sediments of Aliağa
(Aegean Sea) is higher than the world average.
Aliağa, polluted by heavy domestic and industrial
pollution, is located in the eastern Aegean Sea. The
economy of Aliağa is mainly based on oil refineries
such as Tüpraş (Turkey's second-largest oil refinery)
and Petkim (petrochemical plant). In addition, there
are iron and steel mills, two thermal power plants
(natural gas-based), fertiliser and paper mills, and
many other industrial facilities in the gulf, [15].
In Italy, the specific activity of 226Ra in sediment
samples is lower than the average world value in all
cases, except for sites I6 and I7. The activity
concentration of 232Th is higher than the worldwide
one only for sites I5, I6, and I7. The activity
concentration of 40K is higher than the average
world value for all investigated samples, [10].
The levels of heavy metals (Fe, Mn, Zn, Cu, Ni,
Pb, Cr, and Cd) analyzed in samples collected from
Turkey (Aegean Sea) and Italy (Calabria region) are
summarized in Table 2.
In this study, all the metals analyzed and the
average values obtained at the sampling sites are
listed as follows: Fe > Mn > Zn > Cr > Cu > Ni >
Pb > Cd.
The calculated radium equivalent activities vary
from 53.8 (A2) to 226.8 (A8) Bq kg-1 with an
average of 105.1 Bq kg-1 for Turkey (Aegean Sea)
and from 75.4 (I2) to 249.7 (I6) Bq kg-1 with an
average of 145.7 Bq kg-1 for Italy (Calabria region).
Thus, the values of Raeq of 226Ra, 232Th, and 40K
found in sediment samples were lower than the
upper limit of Raeq is 370 Bq kg-1.
Table 2. The concentrations of heavy metals in
marine sediment for all sites (mg kg−1 dw)
Parameters
Fe
Mn
Zn
Cu
Ni
Pb
Cr
Cd
Aegean
Sea
(Turkey)
Min
2175
40
3
3
3
1
9
0.01
Max
18470
545
84
36
33
16
65
0.05
Mean
6995
187
30
14
10
7
22
0.02
Calabria
region
(Italy)
Min
2689
51
8
2
2
2
3
0.01
Max
16834
263
43
13
16
20
28
0.09
Mean
8140
198
25
6
6
7
11
0.05
In this study, the absorbed dose rate due to 226Ra,
232Th, and 40K in sediment varied from 25.77 to
107.16 nGyh-1 with an average of 50.49 nGyh-1 for
Türkiye and that for Italy varied from 37.01 to
116.78 with an average value of 69.88 nGyh-1. In
Italy, the absorbed dose rate is lower than the world
average value (59 nGyh-1) only for sites I2, I3, and
I4. In Türkiye, the absorbed dose rate is higher than
the world average value (59 nGyh-1) only for sites
A7 and A8. The values obtained are generally
comparable with the world average of 59 nGyh-1.
The outdoor AEDE values for Italy marine
sediment samples in sites I5, I6, and I7 and Türkiye
marine sediment samples in sites A7 and A8 exceed
the world average value of 85 μSv y-1.
The Hex index is lower than unity for all
investigated samples, thus reasonably avoiding any
possible radiological health risks for humans, [16].
The Hex index is less than unity for all samples
examined, therefore radiological health risks for
humans are not considered to be a risk for both
Turkey and Italy.
4 Conclusion
Heavy metal pollutants and natural radioactivity
concentrations in the marine environment are one of
the most severe pollution concerns. These elements,
indeed, attach to particles in marine ambiance and
then accumulated in sediments.
The sources of these elements in the marine
environment can be either naturally coming from
the Earth's crust or anthropogenic such as industrial
activity and mining. However, alteration in their
concentration in natural ecosystems has led to an
understanding of the adverse effects over the past
decades since they can enter the food chain through
the ingestion of marine foods. So, high
concentrations of heavy metals and radionuclides in
the sediments have a great effect on the food chain
WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT
DOI: 10.37394/232015.2023.19.57
Serpil Aközcan, Simona Mancini,
Selin Özden, Valentina Venuti,
Francesco Caridi, Giuseppe Paladini, Michele Guida
E-ISSN: 2224-3496
594
Volume 19, 2023
and can cause a major hazard to the aquatic
environment and human health.
The activity concentration of natural
radionuclides, 226Ra, 232Th, and 40K was quantified
by using HPGe gamma spectrometry for marine
sediments collected from the Calabria region (Italy)
and Aegean Sea (Türkiye). Heavy metals such as
Mn, Fe, Ni, Cu, Zn, Cr, Cd, and Pb in sediment
samples were measured using ICP-OES and ICP-
MS.
The activity concentrations of 226Ra, 232Th and 40K
determined in this study are comparable with other
studies in the Mediterranean area performed in the
area of Cyprus, [17], Greece, [18], where
anthropogenic activities in the nearby affecting the
area were no detected. In particular, the mean
activity concentrations of 226Ra, and 232Th were
lower than the value of the world averages where
40K was greater than that. In the present study, the
calculated Hex values for all sediment samples are
less than unity, which does not cause any harm to
the population in all regions.
Heavy metal results showed that Fe is the most
abundant metal in the sediment samples analysed in
this study due to the abundance of iron in the
structure of the earth's crust, [7]. Also, on average,
the heavy metal concentrations in the Aegean Sea
sediments are similar to those in the sediments of
the Calabria region.
Evidence is provided for the evaluation of coastal
sediment metal toxicity and radionuclide
contamination by comparing two different countries
(Turkey and Italy), sea (Aegean Sea and
Mediterranean Sea), and coastal areas.
References:
[1] E. Menshikova, R. Perevoshchikov, P. Belkin,
and S. Blinov, “Concentrations of natural
radionuclides (40K, 226Ra, 232Th) at the
potash salts deposit”, J.Ecological
Engineering, vol. 22(3), 2021, pp. 179-187.
[2] P. Kuzmanović, N. Todorović, L. Filipović
Petrović, D. Mrđa, S. Forkapić, J. Nikolov
and J. Knežević, “Radioactivity of building
materials in Serbia and assessment of
radiological hazard of gamma radiation and
radon exhalation”, J. Radioanalytical and
Nuclear Chemistry, vol. 324, 2020, pp. 1077-
1087.
[3] E. Bavarnegin, M. Vahabi-moghaddam, A.
Babakhani, and N. Fathabadi, “Analytical
study of radionuclide concentration and radon
exhalation rate in market available building
materials of Ramsar”, J. Theoretical and
Applied Physics, vol. 6, 2012, pp. 1-6.
[4] D. Joksimović, A. Perošević, A. Castelli, B.
Pestorić, D. Šuković and D. Đurović,
“Assessment of heavy metal pollution in
surface sediments of the Montenegrin coast: a
10-year review”, J. Soils and Sediments, vol.
20, 2020, pp. 2598-2607.
[5] A.S. Guseva, S.A. Ustinov, V.A. Petrov,
“Distribution of natural radionuclides in the
soils on the territory of the New Moscow”,
Geology and Exploration, vol. 5, 2019, pp.
88–94.
[6] M.H.E. Monged, H.B. Hassan and S.A. El-
Sayed, “Spatial distribution and ecological
risk assessment of natural radionuclides and
trace elements in agricultural soil of
northeastern Nile Valley, Egypt”, Water, Air,
and Soil Pollution, vol. 231(7), 2020, pp. 338.
[7] A. Apaydın, H. Kabaoğlu, G. Apaydın, M.
Şirin, E. Cengiz, O.K. Köksal and E.
Tıraşoğlu, “Evaluation of ecological risk,
source, and spatial distribution of some heavy
metals in marine sediments in the Middle and
Eastern Black Sea region, Turkey”,
Environmental Science and Pollution
Research, vol. 29(5), 2022, pp. 7053-7066.
[8] S. Topcuoğlu, Ç. Kırbasoğlu and N. Güngör,
“Heavy metals in organisms and sediments
from Turkish Coast of the Black Sea, 1997–
1998”, Environ Int, vol. 27, 2002, pp. 521–
526.
[9] Element, C. A. S. "Method 3051A microwave
assisted acid digestion of sediments, sludges,
soils, and oils." Z. Für Anal. Chem, vol. 111
2007, pp.362-366.
[10] F. Caridi, M. Messina, G. Faggio, S.
Santangelo, G. Messina and G. Belmusto,
“Radioactivity, radiological risk and metal
pollution assessment in marine sediments
from Calabrian selected areas, southern Italy”,
The European Physical Journal Plus, vol.
133(2), 2018, pp. 65.
[11] J.Beretka and P.J. Mathew, “Natural
radioactivity of Australian building materials,
industrial wastes and by-products”, Health
Phys, vol. 48, 1985, pp. 87–95.
[12] M. Tufail, M.Y. Hussain and M. Akram,
“Short Communication Primordial
radionuclides contamination level in fertilized
farms soils of Faisalabad-Pakistan “, Soil
Environ, vol. 30, 2011, pp. 88–94.
[13] S. Aközcan, F. Külahcı and Y. Mercan, “A
suggestion to radiological hazards
characterization of 226Ra, 232Th, 40K and
WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT
DOI: 10.37394/232015.2023.19.57
Serpil Aközcan, Simona Mancini,
Selin Özden, Valentina Venuti,
Francesco Caridi, Giuseppe Paladini, Michele Guida
E-ISSN: 2224-3496
595
Volume 19, 2023
137Cs: spatial distribution modelling”, J.
Hazardous materials, vol. 353, 2018, pp. 476-
489.
[14] UNSCEAR, Report to General Assembly with
Scientific Annexes, United Nations, New
York, 2000.
[15] S. Özden and S. Aközcan, “Natural
radioactivity measurements and evaluation of
radiological hazards in sediment of Aliağa
Bay, İzmir (Turkey)”, Arabian Journal of
Geosciences, vol. 14, 2021, pp. 1-14.
[16] F. Caridi, M. D’Agostino, A. Belvedere, S.
Marguccio, G. Belmusto and M.F. Gatto,
“Diagnostics techniques and dosimetric
evaluations for environmental radioactivity
investigations”, J. Instrum, vol. 11, 2016, pp.
C10012.
[17] A. Abbasi, F. Mirekhtiary. Heavy metals and
natural radioactivity concentration in
sediments of the Mediterranean Sea coast,
Marine Pollution Bulletin, Volume 154, 2020,
111041, ISSN 0025-326X
[18] Fouskas, F., Godelitsas, A., Argyraki, A. et al.
Metal concentrations and radioactivity in
sediments at the northern coastal zone of
Ikaria Island, eastern Mediterranean, Greece. J
Radioanal Nucl Chem 317, 55–68 (2018)
Contribution of Individual Authors to the
Creation of a Scientific Article (Ghostwriting
Policy)
The authors equally contributed in the present
research, at all stages from the formulation of the
problem to the final findings and solution
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 conflict of interest to declare.
Creative Commons Attribution License 4.0
(Attribution 4.0 International, CC BY 4.0)
This article is published under the terms of the
Creative Commons Attribution License 4.0
https://creativecommons.org/licenses/by/4.0/deed.en
_US
WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT
DOI: 10.37394/232015.2023.19.57
Serpil Aközcan, Simona Mancini,
Selin Özden, Valentina Venuti,
Francesco Caridi, Giuseppe Paladini, Michele Guida
E-ISSN: 2224-3496
596
Volume 19, 2023