Estimation of sedimentation rate in the Middle and South Adriatic Sea using Cs-137

Abstract

137Cs activity concentrations were studied in the sediment profiles collected at five locations in the Middle and South Adriatic.
In the sediment profiles collected from the South Adriatic Pit, the deepest part of the Adriatic Sea, two 137Cs peaks were identified. The peak in the deeper layer was attributed to the period of intensive atmospheric nuclear weapon
tests (early 1960s), and the other to the Chernobyl nuclear accident (1986). Those peaks could be used to estimate sedimentation
rates by relating them to the respective time periods. Grain-size analysis showed no changes in vertical distribution through
the depth of the sediment profile, and these results indicate uniform sedimentation, as is expected in deeper marine environments.
It was not possible to identify respective peaks on more shallow locations due to disturbance of the seabed either by trawlers
(locations Palagruža and Jabuka) or by river sediment (location Albania). The highest sedimentation rates were found in Albania
(∼4 mm y−1) and Jabuka (3.1 mm y−1). For Palagruža, the sedimentation rate was estimated to be 1.8 mm y−1, similar to the South Adriatic Pit where the sedimentation rate was estimated to be 1.8±0.5 mm y−1. Low sedimentation rates found for the Middle and South Adriatic Sea are consistent with previously reported results for
the rest of the Mediterranean.

Full text

ESTIMATION OF SEDIMENTATION RATE IN THE MIDDLE
AND SOUTH ADRIATIC SEA USING
137
Cs
Branko Petrinec1,*, Zdenko Franic
´1, Nikolina Ilijanic
´2, Slobodan Miko2, Marko S
ˇtrok3and Borut Smodis
ˇ3
1
Radiation Protection Unit, Institute for Medical Research and Occupational Health, Ksaverska cesta 2,
PO Box 291, HR-10001 Zagreb, Croatia
2
Department for Mineral Resources, Croatian Geological Survey, Sachsova 2, HR-10000 Zagreb, Croatia
3
Joz
ˇef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
*Corresponding author: petrinec@imi.hr
Received July 28 2011, revised November 4 2011, accepted November 4 2011
137
Cs activity concentrations were studied in the sediment profiles collected at five locations in the Middle and South Adriatic.
In the sediment profiles collected from the South Adriatic Pit, the deepest part of the Adriatic Sea, two
137
Cs peaks were identi-
fied. The peak in the deeper layer was attributed to the period of intensive atmospheric nuclear weapon tests (early 1960s), and
the other to the Chernobyl nuclear accident (1986). Those peaks could be used to estimate sedimentation rates by relating them
to the respective time periods. Grain-size analysis showed no changes in vertical distribution through the depth of the sediment
profile, and these results indicate uniform sedimentation, as is expected in deeper marine environments. It was not possible to
identify respective peaks on more shallow locations due to disturbance of the seabed either by trawlers (locations Palagruz
ˇa and
Jabuka) or by river sediment (location Albania). The highest sedimentation rates were found in Albania (∼4mmy
21
) and
Jabuka (3.1 mm y
21
). For Palagruz
ˇa, the sedimentation rate was estimated to be 1.8 mm y
21
, similar to the South Adriatic Pit
where the sedimentation rate was estimated to be 1.8+++++0.5 mm y
21
. Low sedimentation rates found for the Middle and South
Adriatic Sea are consistent with previously reported results for the rest of the Mediterranean.
INTRODUCTION
In marine and coastal environments, radiotracer tech-
niques, using either natural or anthropogenic radio-
nuclides, have proved to be extremely useful tools to
investigate various oceanographical, geochemical,
biological and other processes, as well as the behav-
iour and fate of contaminants such as radionuclides,
metals, organic and inorganic pollutants, etc.
Because of their ubiquitous nature, radioactive iso-
topes of caesium and strontium, particularly
137
Cs and
90
Sr,thatoriginatedinanatmosphericnucleartest
conducted in the 1960s are especially important radio-
active tracers in physical oceanography for water mass
transport, sedimentation processes, etc. Larger quan-
tities of radioactive isotopes of caesium have also been
introduced into the environment, including the
Adriatic Sea, by the Chernobyl nuclear accident
(1,2)
.
Its almost unlimited solubility and chemical similarity
to potassium (K) means that it can be easily assimi-
lated by terrestrial and aquatic organisms, and its bio-
availability in natural systems depends on the sorption
properties of the solid phases
(3)
.
In marine sediments,
137
Cs can be deposited by a
variety of mechanisms, including fixation on sus-
pended matter and sedimentation, direct precipita-
tion of colloidal forms, direct fixation by adsorption
and deposition of organic waste
(4)
.
The organic frac-
tion present is important in terms of the binding
and fixation of
137
Cs to sediments. Cs is also
strongly adsorbed on clay particles because of their
high sorption properties (large surface area and fine
particle size) and abundance in natural systems
(5)
.It
has been demonstrated that at low concentrations Cs
sorbs strongly on micaceous minerals such as illite
(6)
.
The concentration of
137
Cs in marine sediments is
influenced by particle size, mineral composition and
content of organic matter.
The use of caesium as a time marker assumes
no mobility within the sediment once it is deposited.
In this context,
137
Cs that originated from the
Chernobyl nuclear accident provided a unique
opportunity to trace caesium behaviour in the Adriatic
coastal environment. Radioactive isotopes of caesium,
particularly
134
Cs and
137
Cs, were delivered to the
seabed in a relatively high amount and short time.
Their depth distribution was then driven by sediment
accumulation, mixing and diffusion through the water.
However, due to the much shorter radiological half-
life of
134
Cs (2.065 y), compared with that of
137
Cs
(30.17 y), it soon decayed. Peaks of
137
Cs activity
occurring within the Adriatic sediment were emplaced
in 1963 (the year of maximum fallout from atmospher-
ic weapon testing) and in 1986 (related to the
Chernobyl event). It should be noted that
134
Cs, being
a shielded radionuclide, is not produced in explosions
of nuclear weapons in any significant amount and can,
therefore, be introduced into the environment only
through discharge from nuclear objects.
#The Author 2011. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com
Radiation Protection Dosimetry (2012), Vol. 151, No. 1, pp. 102 –111 doi:10.1093/rpd/ncr449
Advance Access publication 12 December 2011
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from

In this investigation, distribution of
137
Cs radio-
nuclide through the middle and southern Adriatic
Sea was determined in sediments collected on five
locations in order to better understand some of the
key processes that influence the distribution of radio-
nuclides in the topmost part of the sediment column
and to estimate sedimentation rates.
The Adriatic Sea is an epicontinental semi-
enclosed sea, forming a distinct sub-region within
the Mediterranean Sea region. It is a deeply
indented gulf, 800 km long and 200 km wide, situ-
ated between the Apennine and Balkan peninsulas,
on longitudes between 128150E and 198450E and lati-
tudes between 398450N and 458450N (Figure 1)
(7,8)
.
The southern border of the Adriatic Sea is the
Strait of Otranto by a line running from the mouth
of the Buttrinto River (398440N) in Albania to Cape
Karagol in Corfu, through this island to Cape
Kephali (these two capes are in latitude 398450N)
and on to Cape Santa Maria di Leuca
(9)
. The
surface area of the Adriatic Sea is 138 595 km
2(10)
while the total length of the Adriatic coastline
(mainland and islands) is 8281 km
(11)
. The Croatian
islands area (Figure 1)
(8)
makes the second-largest
archipelago in the Mediterranean. The Croatian
part of the Adriatic Sea with 79 islands, 525 islets,
and 642 rocks and rocks awash (1246 total) extends
on 4398 km of insular coastline length and 6278 km
of coastline length
(12)
. The shallowest part of the
Adriatic Sea is in the Gulf of Trieste, and its deepest
part is in the South Adriatic Pit (1233 m)
(7)
.
According to sediment types and their origin, two
zones of the Adriatic seabed are distinguished: exter-
nal and inshore. The external zone covers the deep-
sea area, from the islands towards the open sea,
which is divided into a northern area covered with
sand and a southern area covered with mixed sedi-
ments. The northern area occupies the entire north
Adriatic as far as the line connecting the island of
Kornat with Pescara. The seabed is covered with
sand and in some places with a mixture of sand,
mud and silt (Figure 2)
(8)
. According to Frignani
et al.
(13)
,
.
the highest mass accumulation rates occur
near the Po delta, due to the high supply of sedi-
mentary material. There the values for sedimenta-
tion rate range between 0.5 and 1.8 g cm y
21
.
The following locations were investigated in this
study: Jabuka and Palagruz
ˇa in the middle Adriatic
Sea, two locations in the South Adriatic Pit (SA PIT
1 and 2) and Albania (ST.7) in the southern part of
the sea. The middle part of the Adriatic Sea has
interesting geological characteristics, as it has been
discovered that the islands Jabuka and Brusnik
consist of rocks of magmatic origin
(14)
. It is well
known that magmatic rocks show higher levels of
background radiation, while sedimentary rocks have
much lower levels of radiation
(15)
, which also proved
to be true in the case of the Adriatic Sea
(16)
.
Jabuka is an uninhabited, solitary and separated
island in the middle Adriatic Sea, situated 50 km
west from the island Vis. It is a small island (surface
area 0.02 km
2
) with a height of 97 m
(12)
. It has a
simple conical form and the coast is steep and
hardly approachable. The island is composed of
magmatic rocks, dark in colour, which could be
characterised as quartz-diabase. Mineral compos-
ition is dominated by plagioclase and pyroxene,
biotite, quartz, chlorite and apatite.
The islands of Palagruz
ˇa constitute an archipelago
on the open sea, which is composed of 10 islands of
various sizes. It is situated 125 km south from the
city of Split. The main island, Vela Palagruz
ˇa, has a
height of 92 m and a surface area of 0.28 km
2(12)
.It
is dominantly composed of dolomite rocks.
The South Adriatic Pit is the deepest part in the
Adriatic Sea, away from the coast with no influence
of material supplied by the rivers.
From a geological standpoint, the last station on
which the sediments were taken, Albania, belongs to
the Dinarides, related to the Alpine/Mediterranean
orogenesis where the coast is composed of dolomite
rocks.
Radioecological monitoring in the Adriatic Sea
water, especially on the Eastern coast, started in the
early 1960s and still takes a significant part in an
extended and ongoing monitoring programme of
radioactive contamination of the human environ-
ment in Croatia. The results of this monitoring are
well documented
(7,17 –20)
. The long-term data on
90
Sr activity concentrations in the Adriatic Sea
water, which are efficient intrinsic tracers of sea-
water movement, allowed estimation of the Adriatic
Sea water turnover time that was estimated to be
3.4 years
(1,21)
. In addition, the assessment of the
radiological impact on a population as well as on
the environment is of particular importance since it
may have a significant contribution to the collective
radiation dose of a population.
The sediment samples analysed in this paper were
collected during the ‘International Scientific Cruise
to Adriatic and Ionian Seas’, 17– 28 September
2007, organised under the International Atomic
Energy Project (IAEA) regional TC project RER/
7/003 ‘Marine Environmental Assessment of the
Mediterranean Region’.
MATERIALS AND METHODS
Sampling and sample preparation
Before the sampling of representative samples from
the seabed, some preliminary investigations with
‘side scan sonar’ were performed. In this investiga-
tion, a box-corer with a diameter of 10 cm was used
as a tool for sediment sampling and the depth of the
sampling was 30 cm (Figure 3). Samples were taken
ESTIMATION OF SEDIMENTATION RATE USING
137
Cs
103
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from

Figure 1. Bathymetric map of the Adriatic Sea
(8)
. The northern part is considerably shallower than the middle and southern parts.
Figure 2. Map of the texture of sediments in the Adriatic Sea
(8)
. The northern part is sandier, while the middle and southern parts are dominantly covered by silt.
B. PETRINEC ET AL.
104
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from

on the following locations (Table 1): South Adriatic
Pit 1 and 2 (SA PIT 1 and 2), Jabuka, Palagruza
and Albania (ST.7). Locations, except for Albania,
were generally chosen to be in the open sea area to
minimise the influence of suspended matter from the
rivers and other land sediments. Samples from SA
PIT 1 and SA PIT 2 were selected as the deepest in
the Adriatic Sea. Samples were cut into slices of
2 cm, freeze-dried and transported to the laboratory.
Before further analysis, samples were dried at a
temperature of 60 –808C
(22)
.
Gamma-ray spectrometry
A gamma-ray spectrometry system, based on a High-
Purity Germanium Coaxial Photon Detector System
ORTEC HPGe detector (FWHM 2.24 keV at 1.33
MeV
60
Co and relative efficiency 74.2 % at 1.33
MeV), coupled to a computerised data acquisition
system was used to analyse collected samples. The
detector was shielded by a 10-cm-thick lead well
internally lined with 2 mm copper and 2 mm
cadmium foils. Energy and efficiency calibration of
the gamma spectrometer was carried out using cali-
bration sources supplied by Czech Metrological
Institute covering the energy range between 80 and
2500 keV
(22)
. Quality assurance and intercalibration
measurements were conducted through participation
in international intercalibration programmes orga-
nised by IAEA, World Health Organization (WHO)
and Joint Research Center (JRC). The testing
method is accredited by the Croatian Accreditation
Agency
(23)
according to ISO Norm 17025.
Laser diffractometry
Grain-size distribution was analysed by Beckman-
Coulter LS 13320, an instrument based on the laser
Table 1. Sampling locations.
Location Date Geographic coordinates Depth Sampling
SA PIT 1 (South Adriatic Pit 1) 29. 9. 2007. N 42820020.7700 E17847018.2100 1041.4 Box corer 1
SA PIT 2 (South Adriatic Pit 2) 29. 9. 2007. N 42820044.7000 E17844049.0900 1030.0 Box corer 2
Jabuka 25. 9. 2007. N 43803010.2500 E15816030.9400 230.8 Box corer
Palagruz
ˇa 3. 10. 2007. N 42828034.8600 E16811027.0900 169.8 Box corer
Albania (ST.7) 2. 10. 2007. N 41843024.3300 E19819054.2900 59.0 Box corer
Figure 3. Locations of the sampling with the box-corer.
ESTIMATION OF SEDIMENTATION RATE USING
137
Cs
105
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from

diffractometer method. Samples were immersed in
de-ionised water, left overnight and dispersed in an
ultrasound bath for 3 min. The instrument measures
particle size in the range 0.4 –2000 mm. This range
is achieved by combining the results from laser light
dispersion with the results from polarised intensity
of differential scattering. Measurements were per-
formed in a module for measurement in de-ionised
water (Aqueous Liquid Module). Grain-size compos-
ition was determined on the sea-bottom sediment
samples from Jabuka, Palagruz
ˇa, SA PIT 1, SA PIT
2 and Albania (ST.7). Samples from the upper part,
middle part and the bottom of the profiles were
taken for analysis. Sediments were then classified
according to the internationally accepted classifica-
tion of sediments
(24)
.
RESULTS AND DISCUSSION
Grain-size analysis
The results of grain-size analysis of sediments from
all the five locations showed that samples from SA
PIT 1 and SA PIT 2 contain 1–2 % of sand, 58 –62
% of silt and 36–40 % of clay. Similar composition
was also identified in the sample from location
Jabuka, which is much shallower (231 m) compared
with the previous two locations. Samples from
Palagruz
ˇa location at a depth of 170 m had a slightly
lower content of silt (53– 59 %) and clay (30– 34 %),
but a higher content of sand (almost 16 %). Sample
ST.7 (Albania) taken from a depth of 59 m showed a
composition of ,1 % of sand, around 72 % of silt
and around 27 % of clay, which is consistent with the
fact that the Bojana River (Buna in Albanian) and
the Drim River deliver large contents of sediment
material from the mainland. Despite being short, the
river has quite a large watershed, covering 5187 km
2
,
because the whole drainage area of Lake Scutari, the
largest lake in south-eastern Europe, is also part of it.
Also, due to the waters from the Great Drin, the
Bojana/Buna ranks second place among all tributar-
ies to the Adriatic, measured by the annual discharge,
after the Po in Italy with 352 m
3
s
21(25)
.
Generally, from the grain-size analysis, as it did
not show significant differences in their distribution
through the depth profile, it can be concluded that
on all locations, except for Albania (which is
shallow and influenced by the river), sedimentation
is quite uniform, as should be expected in deeper
marine environments.
Gamma-spectroscopic analysis
The results of the gamma-spectrocopic analysis of
the samples are shown in Table 2.
137
Cs concentra-
tions are similar in samples SA PIT 1 (Figure 4) and
SA PIT 2 (Figure 5). In the upper part of the pro-
files, exponential fall of the activity concentration of
137
Cs from cca 10 Bq kg
21
to around 0.5– 0.6 Bq
kg
21
in deeper layers is obvious. In samples from
Palagruz
ˇa, almost all
137
Cs is retained in the few
upper layers and after that it falls to a value of 0.6
Bq kg
21
. Values for location Jabuka are consistent
with earlier investigations
(26)
. Results for activity
concentrations of
137
Cs for the samples from
Albania differ from the others. Namely, samples
from Albania were taken on the location where the
sea was quite shallow while the location itself was
closest to the coast and highly influenced by the
Bojana River and the Drim River. It could be
argued that most of the
137
Cs is transported by the
Table 2.
137
Cs activity concentrations in the analysed locations.
Layer in cm Activity concentration
137
Cs in Bq kg
21
SA PIT 1 SA PIT 2 Palagruz
ˇa Jabuka Albania
0–2 8.79+0.83 10.42+0.72 4.05+0.58 5.07+0.62 11.80+0.71
2–4 3.70+0.51 5.53+0.28 3.98+0.49 4.27+0.42 12.00+0.65
4–6 2.97+0.46 3.66+0.41 3.84+0.46 4.20+0.41 12.25+0.51
6–8 1.98+0.49 3.22+0.45 2.43+0.44 4.23+0.37 11.48+0.28
8–10 1.27+0.39 1.37+0.21 1.84+0.44 3.93+0.52 9.11+0.57
10–12 0.58+0.39 0.91+0.37 0.93+0.28 3.47+0.47 10.85+0.29
12–14 1.37+0.36 0.86+0.38 0.90+0.39 2.51+0.46 11.81+0.45
14–16 0.71+0.36 0.82+0.38 0.59+0.38 1.37+0.41 9.75+0.56
16–18 1.13+0.37 0.54+0.38 0.54+0.36 1.07+0.22 5.34+0.48
18–20 0.70+0.38 0.61+0.39 0.44+0.37 1.14+0.40 2.01+0.42
20–22 0.80+0.39 1.16+0.36 0.62+0.37 0.58+0.39 2.03+0.39
22–24 0.49+0.38 0.53+0.37 0.56+0.36 0.52+0.39 0.71+0.35
24–26 0.48+0.37 0.80+0.37 0.72+0.41 0.40+0.38 0.83+0.38
26–28 0.40+0.36 0.67+0.40 0.83+0.38 0.69+0.40 1.17+0.36
28–30 0.35+0.37 0.63+0.41 0.50+0.38 0.22+0.07 0.61+0.38
B. PETRINEC ET AL.
106
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from

river runoff from the mainland and deposited on
the sea bottom. This is the reason for higher values
for sedimentation rates and retaining
137
Cs, even to
20 cm of the depth.
These results show that almost all
137
Cs is retained
in the upper parts of the sediments. In the lower
parts, the activity concentration of
137
Cs is pretty
much constant. Barisic et al. (1996) obtained similar
results in previous investigations. The existence of
137
Cs in the lower parts of the sediments can be
explained by cationic exchange with ions of potas-
sium in clay minerals in sediments
(27,28)
.
In order to estimate the effective depth for reten-
tion of
137
Cs, for samples from all locations, fitting
of the results to the following exponential function
was performed (Figures 4–8):
AsðtÞ¼Asð0Þekt ð1Þ
The physical meaning of the terms in equation (1)
is as follows: A
s
(t) is the time-dependent activity
concentration of
137
Cs in sediment (Bq kg
21
); A
s
(0)
is the initial activity concentration of
137
Cs in
sediment (Bq kg
21
); and 1/k¼d
1/2,eff
is the
effective (observed) depth for retention of
137
Cs in
sediments (cm).
Figure 4. Activity concentration
137
Cs of the samples from SA PIT 1.
Figure 5. Activity concentration
137
Cs of the samples from SA PIT 2.
ESTIMATION OF SEDIMENTATION RATE USING
137
Cs
107
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from

From the resulting coefficients, it is possible to
estimate the mean depth for retention of
137
Cs. For
the South Adriatic Pit (SA PIT), this value has been
found to be 4 cm, for Palagruz
ˇa 8.5 cm, for Jabuka
12.5 cm and for Albania 15.5 cm. It should be
noted, however, that in the entire area around the
islands of Jabuka and Palagruz
ˇa is a major fishing
site with quite intensive fishing activities. Therefore,
trawlers are constantly disturbing the seabed,
causing the mixing of sediments and therefore allow-
ing
137
Cs to penetrate into deeper layers.
Consequently, for the estimation of sedimentation
rate using
137
Cs only locations in the South Adriatic
pit are representative.
As
137
Cs is fission product, i.e. anthropogenic
radionuclide, it is present in the environment since
the first atmospheric explosions of nuclear weapons.
The most intensive period of nuclear weapon tests
was around the 1960s, resulting in the introduction of
large quantities of
137
Cs in the marine environment.
The second peak of
137
Cs in the environment was
caused by the Chernobyl nuclear accident in 1986.
Relating to the time of emission of
137
Cs in the
environment, we can use it as an indicator of sedi-
mentation rate
(29)
. To determine sedimentation rates,
it is possible to identify two peaks on the graphs, the
deeper of which could be related to the period of
1962–64, when most of the nuclear probes hap-
pened, and the other one to the Chernobyl accident
in 1986
(30)
. These two peaks were also identified in
investigations of the fallout and air in Croatia
(31)
.
In the Adriatic Sea, sedimentation rates have been
mainly studied in the North Adriatic in which sedi-
mentation is highly influenced by the Po River.
Figure 6. Activity concentration
137
Cs of the samples from Palagruz
ˇa.
Figure 7. Activity concentration
137
Cs of the samples from Jabuka.
B. PETRINEC ET AL.
108
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from

Therefore, sedimentation in that area is quite high,
and sedimentation rate was estimated to be between
1.6 and 4.8 cm y
21(13)
. As explained earlier, in pro-
files of sediment samples collected in Jabuka and
Palagruz
ˇa locations, two
137
Cs peaks could not be
identified. However, as it is visible that
137
Cs is
mainly retained in the upper sediment layers, in
spite of constant disturbance of sediment profiles by
trawlers, it can indicate a small sedimentation rate.
Similarly, due to the quite strong influence of the
Bojana River and the Drim River on Albania, two
peaks also merged. However, assuming that the
lowest value for
137
Cs activity concentration corre-
sponds to the period of atmospheric nuclear weapon
tests, sedimentation rates for these locations as well
were estimated.
The highest sedimentation rates were found in
Albania (4mmy
21
) and Jabuka (3.1 mm y
21
),
and in Palagruz
ˇa (1.8 mm y
21
).
In the South Adriatic Pit, where two peaks are
more easily identified, sedimentation rate could be
estimated to be 1.8+0.5 mm y
21
, which is quite
similar to the value estimated for Palagruz
ˇa.
However, it should be noted that these results are
just approximate due to method limitations and
large uncertainties in the estimation of the exact lo-
cation of
137
Cs activity concentration peaks in the
sediment profiles.
Nevertheless, sedimentation rates estimated for
Middle and South Adriatic using
137
Cs as a radio-
tracer are consistent with sedimentation rates esti-
mated for the rest of the Mediterranean sea, i.e.
1.1–8.7 mm y
21(32)
using other radiotracer
methods, i.e. the
210
Pb dating method.
CONCLUSIONS
137
Cs activity concentrations were studied in the
sediment profiles collected on five locations in the
Middle and South Adriatic.
The grain-size analysis on all investigated loca-
tions did not show significant differences in their
distribution through depth profile, and it can be con-
cluded that on all locations, except for Albania
(which is highly influenced by the river), sedimenta-
tion is quite uniform.
As in most of the other environmental samples in
sediment profiles,
137
Cs activity concentrations
decreased exponentially, allowing for the estimation
of its effective penetration, i.e. retention depth,
which was estimated to be 4 cm in an undisturbed
location of the South Adriatic Pit and 10– 15 cm on
other locations that are generally disturbed by the
heavy fishing activities of trawlers.
Radiotracer techniques using
137
Cs originating
from atmospheric nuclear weapon tests and the
Chernobyl accident were used to estimate the sedi-
mentation rate on five locations on the Adriatic Sea.
Both peaks were visible only in sediments collected
on the South Adriatic Pit, and equating elapsed time
to peak depth it was possible to estimate the sedi-
mentation rate as 1.8+0.5 mm y
21
.
On other locations
137
Cs peaks merged, allowing
one to estimate only the upper value for the sedi-
mentation rate, which varied between 1.8 mm y
21
in
Palagruz
ˇa and 3.1 mm y
21
in Jabuka.
However, all obtained values are consistent with
the sedimentation rates estimated by other techni-
ques and previously reported in the literature.
Figure 8. Activity concentration
137
Cs of the samples from location near the coast of Albania.
ESTIMATION OF SEDIMENTATION RATE USING
137
Cs
109
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from

FUNDING
This study is a part of the research projects,
‘Radioecology of the Adriatic Sea and Coastal Areas’
and ‘Environmental Radioactivity and Radiation
Protection’ supported by the Croatian Ministry of
Science, Education and Sports of the Republic of
Croatia and IAEA TC project RER/7/003 ‘Marine
Environmental Assessment of the Mediterranean
Region’. The Slovenian Research Agency (contract
no. P2–0075) is gratefully acknowledged.
REFERENCES
1. Franic
´, Z. and Bauman, A. Radioactive contamination
of the Adriatic Sea by
90
Sr and
137
Cs. Health Phys. 64,
62–169 (1993).
2. Franic
´, Z. and Petrinec, B. Marine radioecology and
waste management in the Adriatic. Arh. Hig. Rada.
Toksiko. 57, 347 –352 (2006).
3. Kerpen, W. Bioavailibility of the radionuclides cesium-
137, cobalt-60, manganese-54 and strontium-85 in
various soils as a function of their soil properties.
Methods applied and first results. In: Application of
Distribution Coefficients to Radiological Assessment
Models. Sibley, T. H. and Myttenaere, C., Eds.
Elsevier, pp. 322– 335 (1986).
4. Ligero, R. A., Ramos-Lerate, I., Barrera, M. and
Casas-Ruiz, M. Relationships between sea-bed metals in
estuarine sediments: an example from Poole Harbour,
Southern England. J. Environ. Radioactiv. 29, 191– 211
(2001).
5. Cundy, A. B. and Croudace, I. W. Physical and chem-
ical associations of radionuclides and trace radionuclide
activities and some sedimentological variables.
J. Environ. Radioactiv. 57, 7– 19 (1995).
6. Sawhney, B. L. Selective adsorption and fixation of
cations by clay minerals: A review. Clay Clay Miner. 20,
93–100 (1972).
7. Petrinec, B., Franic
´, Z., Leder, N., Tsabaris, C., Bituh,
T. and Marovic
´,G.Gamma radiation and dose rate
investigations on the Adriatic islands of magmatic
origin. Radiat. Prot. Dosim. 4, 551–559 (2010).
8. Leder, N. Adriatic Sea Pilot. Part B-1. Hydrographic
Institute of the Republic of Croatia, Split (2004).
9. IHO, International Hydrographic Organization. Limits
of Oceans and Seas. Special Publication No. 28. Monte
Carlo (1953).
10. Buljan, M. and Zore-Armanda, M. Oceanographical
properties of the Adriatic Sea. Oceanogr. Mar. Biol.
Ann. Rev. 14, 11 –98 (1976).
11. Leder, N. Designation of the Adriatic Sea as a particu-
larly sensitive sea area. In: First Meeting of the PSSA
Project Group, Oslo (2005).
12. Duplanc
ˇic
´Leder, T., Ujevic
´, T. and C
ˇala, M. Coastline
lengths and areas of islands in the Croatian Part of the
Adriatic Sea determined from the topographic maps at
the scale of 1: 25000. Geoadria. 9(1), 5 –32 (2004).
13. Frignani, M., Sorgente, D., Langone, L., Albertazzi, S.
and Ravaioli, M. Behavior of Chernobyl radiocesium in
sediments of the Adriatic Sea off the Po River delta and
the Emilia-Romagna coast. J. Environ. Radioactiv. 71,
299–312 (2004).
14. Jurac
ˇic
´,M., Novosel, A., Tibljas
ˇ, D. and Balen, D.
Jabuka Shoal, a new location with Igneous rocks in the
Adriatic Sea. Geol. Croatica. 57, 81 –85 (2004).
15. United Nations Scientific Committee on the Effects of
Atomic Radiation (UNSCEAR). Sources and Effects
of Ionizing Radiation, United Nations (2000).
16. Petrinec, B. Radiological characterization of middle
and south Adriatic Sea.Doctoral dissertation, Faculty
of science, University of Zagreb (2010) (in Croatian).
17. Popovic
´,V.Environmental radioactivity in Yugoslavia,
Annual Reports 1962– 1977 (in Croatian). Federal
Committee for Labour, Health and Social Welfare,
Belgrade (1963– 1978).
18. Bauman, A., Cesar, D., Franic
´, Z., Kovac
ˇ,J.,
Lokobauer, N., Marovic
´, G., Marac
ˇic
´, M. and
Novakovic
´,M.Results of environmental radioactivity
measurements in the Republic of Croatia, annual reports
1978–1991 (in Croatian). Institute for Medical
Research and Occupational Health, Zagreb (1979–
1992).
19. Kovac
ˇ, J., Cesar, D., Franic
´, Z., Lokobauer, N.,
Marovic
´, G. and Marac
ˇic
´,M.Results of environmental
radioactivity measurements in the Republic of Croatia,
annual reports 1992– 1997 (in Croatian). Institute for
Medical Research and Occupational Health, Zagreb
(1993–1998).
20. Marovic
´, G., Bituh, T., Franic
´, Z., Gospodaric
´, I.,
Kovac
ˇ, J., Lokobauer, N., Marac
ˇic
´, M., Petrinec, B.
and Senc
ˇar, J. Results of environmental radioactivity
measurements in the Republic of Croatia, annual reports
1998–2009 (in Croatian). Institute for Medical
Research and Occupational Health, Zagreb (1999–
2010).
21. Franic
´,Z.Estimation of the Adriatic Sea water turnover
time using fallout
90
Sr as radioactive tracer. J. Marine
Syst. 57, 1– 12 (2005).
22. Petrinec, B., Franic, Z., Bituh, T. and Babic
´,D.
Quality assurance in gamma-ray spectrometry of
seabed sediments. Arh. Hig. Rada. Toksiko. 62,17–23
(2011).
23. Croatian Accreditation Agency, Registry of
Accreditations. Available on www.akreditacija.hr/
akreditacija/files/read.php?re=5139__akredFile&wr=
1288 (Retrieved on 20-07-2011) (2011).
24. Folk, R. L. The Petrology of Sedimentary Rocks.
Hemphill’s Publishing Company, Austin, Texas (1974).
25. Markovic
´,J.Ð.Enciklopedijski geografski leksikon
Jugoslavije, Svjetlost-Sarajevo. ISBN 86-01-02651-6.
(1990).
26. Hamilton, T., Fowler, S., Miquel, J.-C. and La Rosa, J.
210
Pb dating of sediments from the central and the
northern Adriatic sea: the deposition and preservation of
sedimentary organic carbon: Conference: physical and
biochemical processes of the Adriatic sea, Portonovo,
23–27 April 1996. Lawrence Livermore National
Laboratory, IAEA marine Environmental Laboratory,
Livermore, Monaco (1996).
27. Sawhney, B. L. Potassium and cesium ion selectivity in
relation to clay mineral structure. Clay Clay Miner. 18,
47–52 (1970).
28. Koning, A., Konoplev, A. V. and Comans, R. N. J.
Measuring the specific caesium sorption capacity of
soils, sediments and clay minerals. Appl. Geochem. 22,
219–229 (2007).
B. PETRINEC ET AL.
110
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from

29. Buffoni, G. and Cappelletti, A. On the accumulation-
dispersion processes of the tracer
137
Cs in the Italian
seas. J. Environ. Radioactiv. 37, 155– 173 (1997).
30. A
´lvarez-Iglesias, P., Quintana, B., Rubio, B. and Pe
´rez-
Arlucea, M. Sedimentation rates and trace metal input
history in intertidal sediments from San Simo
´nBay
(Rı
´a de Vigo, NW Spain) derived from
210
Pb and
137
Cs
chronology. J. Environ. Radioactiv. 89, 229– 250 (2007).
31. Franic
´, Z., S
ˇega, K., Petrinec, B. and Marovic
´,G.
Long-term investigations of post-Chernobyl radiocae-
sium in fallout and air in North Croatia. Environ.
Monit. Assess. 148(1– 4), 315– 323 (2009).
32. Othman, I., Al-Masri, M. S. and Al-Rayyes, A. H.
Sedimentation rates and pollution history of the eastern
Mediterranean Sea: Syrian coast. Sci. Total Environ.
248, 27– 35 (2000).
ESTIMATION OF SEDIMENTATION RATE USING
137
Cs
111
by guest on September 10, 2012http://rpd.oxfordjournals.org/Downloaded from