is in the sand sediments from the north locations – Duran Kulak, Shabla, Tulenovo,
Kamen briag and the measured natural nuclide concentrations are:
238 U (4.0–10)
Bq/kg,
232 Th (3.4–10) Bq/kg,
226 Ra (3.6–9) Bq/kg. Low content was obtained at
Sunny beach, Nessebar and Primorsko:
238 U (3–8) Bq/kg,
232 Th (4.4–8) Bq/kg,
226
Ra (3.5–6.2) Bq/kg (Figs. 18.5, 18.7 and 18.8).
The obtained mean values for silt sediments are between sand and slime ones
with exception of Bjala, whose values for
238 U are in the range14–77 Bq/kg.
232 Th 12–110 Bq/kg;
226 Ra 10–77 Bq/kg and are the highest measured at the silt
and slime locations (Figs. 18.6 and 18.7). The data on Fig. 18.5 show that all natural
nuclide content in slime sediments varies around 30 Bq/kg, (except
232
Th at
Kavarna,
238 U at Maslen nos and Chernomoretz), showing some uniformity of
natural nuclide concentrations along the whole coast.
The highest values for natural nuclides content (similarly to Cs) are obtained for
the slime sediments – the obtained results for
238 U vary in the different years in the
range 5–50 Bq/kg,
232 Th – 4.0–35 Bq/kg and
226 Ra – 9–50 Bq/kg. The mean values
of
238
U,
232 Th and
226 Ra specific activities for slime sampling locations are
presented on Fig. 18.3 and these values show the maximum natural nuclide content
at the Bulgarian Black Sea coast. The obtained results show that there is a similarity
between the accumulation of
238 U and
232 Th in Black Sea bed sediments. The
measured U and Th values are within the range of the cited in the literature meaning
that there is no serious contamination with U and Th at the Black Sea coast.
226 Ra
content generally follows the pattern of U and Th with few exceptions.
Samples were taken from deep sediments (56–155 m) from the Bulgarian
territorial waters plus two samples at maximal depth 2040 m and also were
measured for radionuclide content.
Radionuclide content in Black Sea sediments
Gamma Spectroscopy
Bq/kg
Cs-137
Th-234
Th-232
Ra-226
S.Beach
K.Brjag
Nessebar
Primorsko
Sinemoretz
D.Kulak
Shabla
Tulenovo
Albena
Bourgas
Ravda
Pomorie
0
4
8
12
16
20
24
28
Fig. 18.4 Nuclide content in sand sediments along the Bulgarian coast
314
A. Strezov
Kamen briag and the measured natural nuclide concentrations are:
238 U (4.0–10)
Bq/kg,
232 Th (3.4–10) Bq/kg,
226 Ra (3.6–9) Bq/kg. Low content was obtained at
Sunny beach, Nessebar and Primorsko:
238 U (3–8) Bq/kg,
232 Th (4.4–8) Bq/kg,
226
Ra (3.5–6.2) Bq/kg (Figs. 18.5, 18.7 and 18.8).
The obtained mean values for silt sediments are between sand and slime ones
with exception of Bjala, whose values for
238 U are in the range14–77 Bq/kg.
232 Th 12–110 Bq/kg;
226 Ra 10–77 Bq/kg and are the highest measured at the silt
and slime locations (Figs. 18.6 and 18.7). The data on Fig. 18.5 show that all natural
nuclide content in slime sediments varies around 30 Bq/kg, (except
232
Th at
Kavarna,
238 U at Maslen nos and Chernomoretz), showing some uniformity of
natural nuclide concentrations along the whole coast.
The highest values for natural nuclides content (similarly to Cs) are obtained for
the slime sediments – the obtained results for
238 U vary in the different years in the
range 5–50 Bq/kg,
232 Th – 4.0–35 Bq/kg and
226 Ra – 9–50 Bq/kg. The mean values
of
238
U,
232 Th and
226 Ra specific activities for slime sampling locations are
presented on Fig. 18.3 and these values show the maximum natural nuclide content
at the Bulgarian Black Sea coast. The obtained results show that there is a similarity
between the accumulation of
238 U and
232 Th in Black Sea bed sediments. The
measured U and Th values are within the range of the cited in the literature meaning
that there is no serious contamination with U and Th at the Black Sea coast.
226 Ra
content generally follows the pattern of U and Th with few exceptions.
Samples were taken from deep sediments (56–155 m) from the Bulgarian
territorial waters plus two samples at maximal depth 2040 m and also were
measured for radionuclide content.
Radionuclide content in Black Sea sediments
Gamma Spectroscopy
Bq/kg
Cs-137
Th-234
Th-232
Ra-226
S.Beach
K.Brjag
Nessebar
Primorsko
Sinemoretz
D.Kulak
Shabla
Tulenovo
Albena
Bourgas
Ravda
Pomorie
0
4
8
12
16
20
24
28
Fig. 18.4 Nuclide content in sand sediments along the Bulgarian coast
314
A. Strezov