well as the scopes of radiological response time of the Black Sea on the radioactive
contamination of its waters (Polikarpov et al. 2008). The monitoring, which has
been carried out since 1986 has allowed to evaluate the risk of influence of the postaccidental
90 Sr and
137 Cs on the living organisms from the Black Sea ecosystems
(Polikarpov et al. 2008). On the other hand, the study of the migration of radionuclides in the marine environment has made it possible to use them as tracers of
large-scale vertical circulation of the Black Sea waters (Egorov et al. 2001; Gulin
et al. 2011).
However, until recently these studies, particularly with respect
137 Cs, were made
only at the upper 200 m, less commonly for the 500 m layer of the water column of
the Black Sea (Egorov et al. 2001). This was due to the lack of reliable at that time
(or available) methods of
137 Cs concentrations measurements in relatively small
volumes of water, and the sampling of the required sample volume (1000 l or more)
for this procedure at that time from great depths of sea water was quite a challenge.
Recently, this problem is solved by using the new radioanalytical methods, which
allow to significantly reduce the volume of samples to measure the content of
137 Cs,
for example, by precipitating with ammonium phosphomolybdate with followed
beta radiometry or the concentration of samples by classic high sorption method
and with using the high-performance gamma- and liquid-scintillation spectrometry
(Gulin et al. 2015). In the latter case, in the same sample of water can simultaneously identify and
137 Cs, and
90 Sr, without using expensive cesium tracers for its
radiochemical yield, which greatly improves the performance of sampling and
measurement. This method allowed for the first time for the entire period since
the ChNPP accident, to get a full profile of the vertical distribution of
137 Cs in the
deep thickness of the Black Sea (Gulin et al. 2015). Previously, such measurements
were performed only once and only in before Chernobyl period (Vakulovsky et al.
1980).
The purpose of this study was to analyze the contemporary radioecological state
of the Black Sea concerning of the contamination of
90 Sr and
137 Cs after the ChNPP
accident, to make a forecasting of the period of time for achieve of concentrations
of these artificial radionuclides till or less of the pre-accident levels in the balance,
abiotic and biotic components of the Black Sea ecosystems, determination of the
rate of self-purification of the coastal and deep-water areas of the Black Sea from
90
Sr and
137 Cs after the ChNPP accident.
In accordance with the proposed purpose the following tasks were solved:
– to analyze the presented in the literature and own obtained results on the
pollution of the
90 Sr and
137 Cs of water, hydrobionts and bottom sediments of
the different areas of the Black Sea,
– to describe the new data on concentrations of
90 Sr and
137 Cs in the deep waters of
the Black Sea (the data on the content of
137 Cs in the deep water (1500 m) in the
eastern part of the Black Sea for the first time was obtained in 2013),
– to fulfill the assessment of the balance components: the entrance, content and
elimination of
90 Sr and
137 Cs in the coastal, aerobic and anaerobic water column
of the Black Sea as a result of studying of the dynamics of the vertical
276
N.Y. Mirzoyeva et al.
contamination of its waters (Polikarpov et al. 2008). The monitoring, which has
been carried out since 1986 has allowed to evaluate the risk of influence of the postaccidental
90 Sr and
137 Cs on the living organisms from the Black Sea ecosystems
(Polikarpov et al. 2008). On the other hand, the study of the migration of radionuclides in the marine environment has made it possible to use them as tracers of
large-scale vertical circulation of the Black Sea waters (Egorov et al. 2001; Gulin
et al. 2011).
However, until recently these studies, particularly with respect
137 Cs, were made
only at the upper 200 m, less commonly for the 500 m layer of the water column of
the Black Sea (Egorov et al. 2001). This was due to the lack of reliable at that time
(or available) methods of
137 Cs concentrations measurements in relatively small
volumes of water, and the sampling of the required sample volume (1000 l or more)
for this procedure at that time from great depths of sea water was quite a challenge.
Recently, this problem is solved by using the new radioanalytical methods, which
allow to significantly reduce the volume of samples to measure the content of
137 Cs,
for example, by precipitating with ammonium phosphomolybdate with followed
beta radiometry or the concentration of samples by classic high sorption method
and with using the high-performance gamma- and liquid-scintillation spectrometry
(Gulin et al. 2015). In the latter case, in the same sample of water can simultaneously identify and
137 Cs, and
90 Sr, without using expensive cesium tracers for its
radiochemical yield, which greatly improves the performance of sampling and
measurement. This method allowed for the first time for the entire period since
the ChNPP accident, to get a full profile of the vertical distribution of
137 Cs in the
deep thickness of the Black Sea (Gulin et al. 2015). Previously, such measurements
were performed only once and only in before Chernobyl period (Vakulovsky et al.
1980).
The purpose of this study was to analyze the contemporary radioecological state
of the Black Sea concerning of the contamination of
90 Sr and
137 Cs after the ChNPP
accident, to make a forecasting of the period of time for achieve of concentrations
of these artificial radionuclides till or less of the pre-accident levels in the balance,
abiotic and biotic components of the Black Sea ecosystems, determination of the
rate of self-purification of the coastal and deep-water areas of the Black Sea from
90
Sr and
137 Cs after the ChNPP accident.
In accordance with the proposed purpose the following tasks were solved:
– to analyze the presented in the literature and own obtained results on the
pollution of the
90 Sr and
137 Cs of water, hydrobionts and bottom sediments of
the different areas of the Black Sea,
– to describe the new data on concentrations of
90 Sr and
137 Cs in the deep waters of
the Black Sea (the data on the content of
137 Cs in the deep water (1500 m) in the
eastern part of the Black Sea for the first time was obtained in 2013),
– to fulfill the assessment of the balance components: the entrance, content and
elimination of
90 Sr and
137 Cs in the coastal, aerobic and anaerobic water column
of the Black Sea as a result of studying of the dynamics of the vertical
276
N.Y. Mirzoyeva et al.