The cytogenetical effects of long-term irradiation in embryo tissue of gastropod snail (Lymnaea stagnalis L.) as chromosome aberration rate as well as change of structure, level of differentiation, death and cytogenetical stability of hemolymph cell population has been studied. Our researches were carried out during 1998–2007 in water bodies within the Chernobyl Exclusion. The absorbed dose rate for snails from research water bodies within the exclusion zone was registered in the range from 1.8 mGy/year to 3.4 Gy/year. The highest rate was found in snails from lakes, the lowest – from the river ecosystems. Molluscs from the control lakes were characterized by absorbed dose rate about 0.3 mGy/year. The lowest rate of chromosome aberration was determined in molluscs form the control lakes – 1.1–2.0%. The highest rate was found in snails from lake ecosystems – 21–23%. In hemoliph of snails from contaminated lakes of the exclusion zone the quantity of death cells averages 40%, the part of phagocytic cells averages 42% as well as decrease of the young amoebocytes quantity to 10–20.1%. In the control water bodies the part of death cells averages from 2.2 to 5.3% and the quantity of phagocytic was at level 3.0–4.2%. The quantity of young amoebocytes have useful increased here to 79.7–89.6%.

The rate of chromosome aberrations has been studied in higher aquatic plants: common reed, sagittaria, flowering rush and manna. The main water bodies were Glubokoye and Dalekoye-1 Lakes (left-bank flood lands of the Pripyat River), Azbuchin Lake and Yanovsky Crawl (right-bank flood lands of the Pripyat River), Cooling Pond of the Chernobyl NPP as well as Pripyat and Uzh Rivers. In decreasing sequence due to the absorbed dose rate for hydrobionts the first were water bodies of the left-bank flood lands of the Pripyat River, the second ones from right-bank flood lands. The highest chromosome aberrations rate in root meristems was registered in plants from lakes within the left-bank flood lands of the Pripyat River, the lowest one – in plants from the Pripyat and Uzh Rivers. The chromosome aberration rate in closed and slow-running water bodies within the right-bank flood lands of the Pripyat River was in 3–4 times higher than spontaneous mutagenesis level. It seems that spectrum of the main types of chromosome damages in plants of right-bank flood lands determines by chemical mutagens. The type of chromosome damages distribution in plants of the left-bank flood lands points to practically equivalent effects of radiation and chemical factors.

The results of the analyses of plant production and parasitic resistance of common reed (Phragmites australis (Cav.) Trin. ex. Steud) from water bodies within the Chernobyl accident exclusion zone are represented. The heavy damage of common reed by the ergot (Claviceps purpurea (Fr.) Tul.) (up to 50%) from water bodies of the left-bank flood lands of the Pripyat River, which is the most contaminated region of the Chernobyl NPP exclusion zone, has been investigated. Deviations in morphological indexes of reproductive organs of common reed from water bodies of right- and left-bank flood lands of the Pripyat River within 10-km exclusion zone are registered. There are: decrease of panicle width, length and flowers number at inflorescence; differences in seed shape and color. The direct correlation between the absorbed dose rate for higher aquatic plants and plant productivity indexes as well as damage events of common reed by the ergot is proved. The parasitic resistance of common reed from water bodies within Chernobyl accident exclusion zone are decreased according to the increase of absorbed dose rate as well.

The radionuclide contamination of fishes from the Glubokoye and Dalekoye-1 Lakes (left-bank flood lands of the Pripyat River), Azbuchyn Lake and Yanovsky Crawl (right-bank flood lands of the Pripyat River), Pripyat River (near by Chernobyl town) and the main area of the Kyiv reservoir on a modern stage are explored and analyzed. The percentage of 90Sr is shown in organs and fabrics of different fishes by the state on 2005–2007.

Presented studies were carried out during 1997–2007 within Krasnensky flood-lands on the left bank of the Pripyat River, which is the most contaminated region of the Chernobyl accident exclusion zone and where the complex of hydraulic engineering structures as flood protection dams was constructed, which preventing washing away of radioactive substances from soils and changing a hydrological mode of floodplain flows during a high water. In its turn it was by the reason of strengthening of over-moistening and swamping processes within embankment territories. As a result – on a background of the common tendencies of increase of the mobile forms of 90Sr in soils of catchment territories and bottom sediments of the exclusion zone, there is an increase of humic acids concentrations in waterlogged soils of Krasnensky flood-lands. It is also raises the content of the water-soluble forms of 90Sr forming with acids the soluble complexes. Thus the increase of concentrations of the mobile radionuclide forms and their inclusion into biotic circulation of aquatic ecosystems is observed. Such dynamics of 90Sr and 137Cs contents is significantly reflected on dose rate for hydrobionts due to incorporated radionuclides.

Naturally occurring radioactive material (NORM) associated with monazite had its origin before the 20th century. The volume and complexity of monazite NORM wastes increased as the industrial applications of monazite also increased. During and after the WWII the diversified uses of thorium turned monazite into an important commodity. At the end of the 20th century the production of oil and gas from offshore platforms in continental shelves increased remarkably. Hundreds of millions of m3 of produced water from the oil and gas industry, containing NORM wastes and other byproducts, are discharged into the oceans every year. E&P processes mobilize the natural occurring radio-nuclides extant in the oil and gas reservoirs. A wide range of concentrations of 238U and 232Th and their respective progenies, mainly 226Ra, 222Rn and 210Pb (from the 238U series), and 228Ra and 228Th (from the 232Th series) appear in tube scales and sludge. The radium isotopes in NORM wastes generated in the monazite cycle become more bio-available than those isotopes found in wastes from the oil and gas industry. This work discusses some of the problems arising from the existence of monazite cycle and oil and gas industry NORM wastes, and proposes a tentative solution.

There are various scenarios dealing with releases of radionuclides in a water body, for example, accidents in nuclear power plants located in coastal areas, on margins of rivers or lakes. Meager attention has been given, however, to potential accidents with nuclear reactors submerged at sea. The latter type of accidents may occur with partial or total loss of the nuclear reactor core to the adjacent waters. In addition to initial instantaneous releases, one may estimate delayed sources based on rates of leaching or dissolving solid materials which are part of the core. Transport equations were used to estimate concentrations of radionuclides in water. Time dependent functions of concentrations of radionuclides in the aquatic food chain reflect the absorption and elimination processes in the flora and fauna. However, to avoid the multi-parametric complexity which can be inserted in these processes, the model takes into proper consideration in a simplified way the transfer of radionuclides through trophic levels. The model avoids the need to analyze step-by-step the details of transfer factors used to determine radionuclide accumulation in fish, crustaceans, mollusks, and algae. This simplified model may help authorities in the case of an accident with a nuclear reactor submerged at sea.

The paper presents peculiarities of organization and performance of activities on disposition of the high level activity radwaste repository located at the radwaste disposal site of the Russian Research Center “Kurchatov Institute” in Moscow. The process of the radwaste extraction from the repository is described in comparison with similar activities in other old repositories. Tools and equipment used for the radwaste extraction from the repository are listed. Conventional construction machines equipped with a hydraulic hammer or a clamshell were used for destruction of the concrete-encased radwaste mass and extraction of low-level radwaste. Intermediate- and high-level radwaste was extracted by remotely controlled robots operating inside the shielding structure. Gamma visor was used for detection of high-level radwaste or fragments in the mass concrete being destroyed and for pointing remotely controlled robots accordingly. The paper describes peculiarities of radiation monitoring in the course of operations on disposition of the repository. For rapid detection of changes in radiation conditions in the working areas, there was used a gamma locator with on-line transmission of its data to a PC and their processing. The same measuring and extraction equipment were used for remediation of high-level radwaste repository at the Gas Plant complexes.

Radioactive contamination was studied in macrobenthic invertebrates and algae of the Abrosimov, Stepovoy and Tsivolky Bays of the Novaya Zemlya Archipelago and the adjacent regions of the Kara Sea during the cruises 73d and 81st on board R/V Professor Shtokman in the years 2005–2006. Maximum concentration 137Cs in sediment in studied area has been detected in the layer 10–12 cm in the Abrosimov Bay (150 Bq/kg) and in the layer 4–6 cm in the Stepovoy Bay (100 Bq/kg). Concentration of 137Cs in benthos was up to 3.19 Bq/kg of wet weight. The highest concentration has been found in benthos of the Abrosimov and Stepovoy Bays: the holothurian Myriotrochus rinkii, the isopod Saduria sabini, ophiuroids Ophiocten sericeum and Stegophiura nodosa. Myriotrochus rinkii, Saduria sabini and the brown alga Laminaria saccharina were characterized by the highest 137Cs concentration factor – 994, 599 and 425 respectively. Caesium-137 contamination occurs locally in the studied area closed to the radioactive waste disposal and does not affect on qualitative structure of the macrobenthic communities.

The naturally occurring radionuclide 210Po was determined in different components of the Black Sea ecosystem. The specific activity of 210Po in water in the open part of the sea was about 1Bq ⋅ m-3. The range of 210Po specific activity in bottom sediments was 4.5–500 Bq ⋅ kg-1 dry weight depending on their type, area and depth of collection. The highest values were found in the NW part of the Black Sea. Sediment distribution coefficients (Kd) of 210Po for bottom sediments, calculated on a dry weight basis, varied from 0.5 × 104 to 5 × 105. The levels of 210Po specific activity in molluscs and pelagic fishes anchovy and sprat were the highest among the investigated species of the Black Sea biota. Concentration factors (CF) of 210Po, estimated on a wet weight basis, reached 1.5 × 103 for macrophytes, 4 × 103 for total zooplankton, 103–104 for the entire fishes depending on their ecological groups affiliation and (0.7–6.0) × 104 for molluscs. So, the ability of the Black Sea biota to accumulate the natural radionuclide 210Po is comparable with that of similar species from others marine and oceanic areas.