The main objectives of this study were to investigate the distribution features of the 210Po in abiotic (water and bottom sediments) and biotic (zooplankton, mollusks, fish) components of the North Crimean Canal (NCC) aquatic ecosystem and adjacent irrigated soils as well as assessment of the doses received by water organisms from α-radiation of absorbed 210Po. The samples were processed using standard radiochemical methods accepted in international practice. The activity of 210Po in the samples was measured using the alpha-spectrometric OCTETE Plus complex (ORTEC-AMETEK, USA). The measurement error did not exceed 20

In the frame of the radioecological monitoring after the Chernobyl nuclear power plant accident, the features of migration and distribution of artificial radionuclides in the North Crimean Canal (NCC) irrigation system were studied. Standard methods of radiochemical analyzes and modern radiospectrometric equipment were used. It was determined that the irrigation system of the NCC retains 43–59% 90Sr, 59–60% 239+240Pu, and 66–70% 137Cs of the concentration radionuclides entering to irrigated fields with the Dnieper waters. The NCC irrigation system plays the role of a buffer against the radionuclide pollution of the Karkinitsky Bay (the Black Sea). Differences in the accumulation of radionuclides by agricultural crops were revealed. The 90Sr and 239+240Pu transfer factors (TF) for alfalfa were n × 10−2 and n × 10−1, respectively. The TF for wheat, corn, and rice for 90Sr were n × 10−3, and for 239+240Pu—n × 10−2. A radioecological assessment on the safety agriculture along the NCC was made: in the absence of an increase in the entry of the Chernobyl origin radionuclides with the Dnieper river waters to the NCC, the levels of activity concentration of artificial radionuclides in cultivated crops will not exceed the maximum permissible concentration for food raw materials in the coming years.

Determination of 137Cs, 40K and 210Po in water, bottom sediments and suspended matter of river systems of the Can Gio Biosphere Reserve, Vietnam was carried out. The average activity concentration of 137Cs in waters of Ca Gau and Long Tau was 0.89 ± 0.14 and 1.08 ± 0.15 Bq m−3 and was comparable to the levels of this radioisotope in waters of the East Sea. The activity concentration of 137Cs in bottom sediments was 2.23 ± 0.81 and 3.63 ± 1.24 Bq kg−1. The activity concentration of 137Cs in water and bottom sediments could be characterized as low. So, the water areas of the Ca Gau and Long Tau rivers could be attributed to areas with insignificant pollution by technogenic radionuclides. The 210Ро activity concentration in bottom sediments of the Ca Gau and Long Tau rivers ranged from 9.2 ± 1.2 to 25.5 ± 2.1 Bq kg−1, which is typical for river bottom sediments. Such values indicate the absence of anthropogenic enhancement of the entry of this radionuclide into the Can Gio river systems. The 40K activity concentration varied within 467 ± 42–651 ± 39 Bq kg−1 and represented typical values of potassium content in the bottom sediments of coastal water bodies, subject to a significant influence of the lithogenic component of suspended matter.

В работе представлены результаты сравнительной оценки мощностей поглощенных и эквивалентных доз, формируемых у гидробионтов, имеющих сходный тип питания (фильтраторов), от ионизирующего излучения природного радионуклида 210Ро. Объектами исследования послужили черноморские двустворчатые моллюски нескольких видов и типичный обитатель соленых озер Крыма жаброногий рачок Artemia spp. (Crustacea, Anostraca). Отмечена высокая аккумулирующая способность исследуемых гидробионтов: величины коэффициента накопления ими 210Ро варьировал в пределах 104–105. Определено, что значения поглощенных и эквивалентных доз, полученных этими организмами в результате внутреннего облучения αчастицами 210Ро, были близки. Максимальные мощности эквивалентных доз, рассчитанных как для артемий, так и для моллюсков, составили около 10-1 Зв·год-1. Оценка полученных результатов с использованием шкалы Зон хронического действия ионизирующего излучения, предложенной Г.Г. Поликарповым, показало, что дозы, формируемые 210Ро, достигают области «экологической маскировки», что подтверждает значимость 210Ро как основного дозообразующего радионуклида.

Concentrations of 226Ra, 40K, 210Pb, 234Th, 238U, 232Th, and 210Po were determined in bottom sediments of 11 Crimean saline lakes. From lake to lake, concentration of all radioisotopes and their total amount varied. The greatest variability was noted for 226Ra (CV = 1.268), and the smallest for total sum of radionuclides (CV = 0.336). In all lakes, the concentration of studied radionuclides did not exceed the maximum concentrations found in bottom sediments of water bodies in different regions excepting Lake Sasyk-Sivash where 226Ra concentration was slightly higher than previously found the upper limit. There are the inter-lake differences and temporal changes in radionuclide concentrations in the bottom sediments. Salinity is not main determinant of radioisotope concentrations in the lake bottom sediments, but may modify their concentrations in some ranges. The behavior of 210Pb and 210Po under anoxic conditions differs from observed in oxic. Authors conclude that there is no any single factor itself controlling concentrations of radionuclides in the upper layer of bottom sediments in the saline lakes; there is multicausal determination. Only coupling of many factors (physical, chemical, and geochemical properties of radioisotopes, and geological, climatic, and biological) determines radionuclide distribution patterns.

This paper presents the results of radioecological monitoring study of natural radionuclide 210Po in 11 lakes located in different regions of the Crimean peninsula. These investigations of the Crimean salt lakes were conducted for the first time in the history. The main objectives of this work were: to determine the features of the 210Ро behavior in the salt lakes ecosystems, as well as calculation of the doses received by the lakes hydrobionts from α-radiation of absorbed 210Po. Concentrations of 210Po in the water, suspended matter, the bottom sediments and biota were determined by radiochemical processing and α-spectroscopy measurements. The concentrations of dissolved 210Po in the water of investigated lakes were in 0.9-327.1 times higher than in the Black Sea closest regions. The highest concentrations of 210Po in water were determined in the lakes of the Kerchenskaya group. These lakes are located on the territory of Crimea where oil is produced. The 210Ро activity concentrations in the bottom sediments from Crimean salt lakes were comparable with those of the Black Sea coastal zone. Concentration ratio (CR) of polonium in suspended matter ranged from 10 to 104 for different lakes. A significant trend in a decrease of CR values of 210Ро for suspended matter with increasing water salinity was revealed. High levels of 210Po accumulation were noted for adult crustacean Artemia spp. (typical inhabitant of the Crimean saline lakes). The CR of 210Po for adult Artemia spp. reached 105 while the CR of this radionuclide by their cysts was significantly lower. The absorbed doses from 210Po α-radiation calculated for adult Artemia spp. were more than 60 times lower than the permissible dose rate for biota (IAEA, 1992).The obtained results will be used to identify the biogeochemical peculiarities in behavior of the main dose-formative radionuclide 210Po, in the water ecosystems with different salinity, including water reservoirs poorly studied in the radioecological aspect and having extreme condition for the existence of lots of species of hydrobionts, such as hypersaline Crimean lakes.