The accumulation ability of marine ecosystems biotic and abiotic components is one of the water masses self-purification mechanisms. Hydrobionts and suspended matter accumulate anthropogenic substances from the water, thereby contributing to its self-purification. It is important to study the quantitative characteristics of this process in order to assess the ecological state of aquatic ecosystems and a possible impact of anthropogenic substances on marine organisms and ensure their protection. Anthropogenic substances entering the water systems include technogenic radionuclides. Among them, the plutonium radioisotopes 239+240Pu occupy a special place. Being long-lived alpha-emitting radioisotopes, 239+240Pu are especially dangerous if they enter inside the organism. Therefore, it is required to assess hydrobionts accumulation ability in relation to these radioisotopes, and the dose loads that they create on marine biota. This study was carried out in Sevastopol Bay of the Black Sea which was subjected to pollution by anthropogenic radionuclides and is currently serving as a model object for studying the redistribution of 239+240Pu in marine coastal ecosystems. This work was aimed to assess the accumulation ability of hydrobionts and suspended matter in relation to plutonium and the dose loads created by 239+240Pu on marine organisms, representatives of different trophic levels, based on determining the 239+240Pu activity concentration in the components of the bay ecosystem. Representatives of multicellular brown and green algae, bivalves, demersal and pelagic fish, crabs and zooplankton of the subclass Copepoda were studied. The 239+240Pu activity concentration in the ecosystem components was determined by standard radiochemical methods and alpha-spectrometry. The accumulation ability of hydrobionts and suspended matter in relation to 239+240Pu was estimated by the concentration factors (Cf). The dose loads on marine biota were calculated using the ERICA Assessment Tool 2.0 software package. It was found that suspended matter has the highest accumulation ability among the studied components (Cf 239+240Pu – n·105), as well as bivalve mollusks, perennial multicellular brown algae and pelagic predatory fish among the studied hydrobionts (Cf 239+240Pu – n·103). It is concluded that the processes of plutonium redistribution in the bay lead to its deposition in the bottom sediments and long-term biotic components of the bay. At the same time, 239+240Pu are not removed from the ecosystem and, under certain conditions, they can enter the water as secondary pollution. The critical links of the trophic chain in the bay ecosystem according to the dose loads are determined for the link of primary producers: phytoplankton and perennial brown algae, for consumers of the first order – bivalve mollusks, for consumers of the second order – pelagic predatory fish. The paper contains 5 Figures, 1 Tables, and 48 References.

В работе показана возможность применения баромембранного метода для измерения ультранизких концентраций радионуклидов в воде пресноводных водоёмов. Актуальность задачи обусловлена необходимостью определения привноса радионуклидов в водные объекты, используемые предприятиями ядерно-топливного цикла. Радионуклиды естественного и техногенного происхождения, не связанные со сбросами предприятия, всегда присутствуют в таких водных объектах, формируя естественный или техногенно изменённый радиационный фон. Его наличие часто затрудняет идентификацию вклада сбросов предприятия в активность воды, так как штатные методы мониторинга характеризуются очень высоким порогом обнаружения радионуклидов. Традиционные способы определения фоновых концентраций радионуклидов требуют отбора минимум 500 л воды с последующим её выпариванием до образования сухого остатка, а на такую процедуру необходимо не менее пяти рабочих дней. Сократить затраты времени и энергии на выпаривание сотен литров воды можно путём предварительного концентрирования радионуклидов в меньшем объёме пробы баромембранным методом. Для его демонстрации применяли мобильную установку с осмотическими мембранами. Её начальная производительность составляет 6,0 л·мин−1. Осмотические мембраны позволяют разделить исходную пробу из водоёма на два компонента — деминерализованный пермеат и содержащий радиоактивные вещества концентрат. В зависимости от степени минерализации воды исследуемой пробы, установка позволяет проводить за 10–15 ч предварительное концентрирование 500 л до образца объёмом 20 л с минимальными потерями радионуклидов. Этот подход универсален и может быть применён для концентрирования растворённых солей любых тяжёлых металлов и прочих органических соединений. Он позволяет готовить счётные образцы водных проб в гораздо меньшие сроки, чем традиционный метод упаривания.

The 238,239+240Pu activity concentrations in sediments and in water in the Crimean salt lakes were studied. Activity ratio of 238Pu/239+240Pu in depth profiles of sediments was used to estimate the contribution of two main sources of man-made plutonium to the Pu sediment inventory. The most part of the plutonium was of global origin. Concentration factor of the plutonium isotopes in sediments, radiocapacity factor of the lake, the type of biogeochemical behavior of plutonium in these reservoirs and the sediment inventory of 238,239+240Pu in the lakes were evaluated.

This work demonstrates the use of baromembrane method based on reverse osmosis (RO) process. The method is realized on mobile complex, which allows to concentrate and determine ultra-low activity of radionuclides in water cooling ponds of Russian nuclear fuel cycle enterprises. The existence level of radionuclide background creates difficult conditions for identification the contribution of liquid discharges enterprise, as standard monitoring methods have a very high detection level for radionuclides. Traditional methods for determining the background radionuclides concentrations require the selection of at least 500 liters (l) of water, followed by their evaporation to form a dry residue. This procedure with RO membranes requires at least 5 days. It is possible to reduce the time and energy spent on evaporation of hundreds of water liters by pre-concentrating radionuclides in a smaller sample volume with baromembrane method. This approach allows preliminary concentration of water samples from 500 l volume till 20 l volume during several hours. This approach is universal for the concentration of dissolved salts of any heavy metals, other organic compounds and allows the preparation of water countable samples in much shorter time compared to the traditional evaporation method.

Relevance. In connection with the development of nuclear energy, many aquatic ecosystems have been exposed to radioactive substances. Fish, as an element of biota, is capable to accumulate radionuclides. However, fish is a traditional food. The control of the technogenic radionuclides accumulation level in the ichthyofauna is an important link in ensuring human security.Intention. To analyze the long-term data on the content of long-lived technogenic radionuclides 90Sr and 137Cs in the ichthyofauna of the Ob-Irtysh river system for the period from 2004 to 2016 and Beloyarsky pond for the period from 1977 to 2018.Methodology. Fish as a food product was assessed according to two criteria: a) permissible levels of specific activity of radionuclides (SanPiN 2.3.2.1078-01); b) using the indicator of conformity B and the uncertainty of its definition В (GOST 32161-2013 and GOST 32163-2013).Results and Discussion. Fish of all species that live in the river Tetcha, is not suitable for food use according to the criteria of SanPiN 2.3.2.1078-01, GOST 32161-2013 and GOST 32163-2013. The fish of the Ob-Irtysh river system, the habitat of which is located outside the Tetcha, meets the requirements for fish products. In the period from 1977 to 1989 in the Beloyarsk pond the accumulations of technogenic radionuclides in fish in quantities exceeding sanitary and hygienic standards were possible. Currently, the fish of the Beloyarsky pond fully complies with the sanitary and hygienic requirements for the radiation factor and is safe for human consumption.Conclusion. In the ponds exposed to the atomic energy enterprises, it is necessary to continuously monitor the content of long-lived technogenic radionuclides in fish and assess their amount in accordance with the requirements of SanPiN 2.3.2.1078-01 and using the conformity indicator В and the uncertainty of its determination В.

Relevance. New units commissioning at the operating nuclear power plants may be associated with an increase in the radiation load on environment and human beings. The 4th Unit BN-800 was commissioned at the Beloyarsk nuclear power plant (BNPP) in 2016. The Beloyarsk artificial lake created in 1959–1963 serves as a cooling pond. A radioecological study of the cooling pond was performed in 2014 before the BN-800 Unit commissioning. Its results were published in the issue No. 2 of the present journal in 2016.Intention. The objective of the work is to show (comparing with the results of the previous research) the effect of the BN-800 Unit commissioning on the cooling pond radioecological state.Methodology. The samples of water and macrophytes (Potamogeton pectinatus, Ceratophyllum demersum, Spirogyra, Cladophora) were examined at the reference points of the cooling pond.Results and Discussion. It was found that 137Cs decreased in the water by 1.4–5.9 times in all reference points (including the 4th NPP Unit discharge channel) compared to 2014. Potamogeton pectinatus (from the 4th NPP Unit discharge channel) had 3.1 times less 137Cs and 1.4 times less 90Sr than macrophytes from the Pyshma river area below the dam.Conclusion. The BN-800 Unit commissioning was not associated with additional radiation load on the artificial lake. It does not deleteriously affect the natural purification processes after the 1st and 2nd BNPP Units decommissioning. The further preservation of the Beloyarsk artificial lake natural resources assumes a systematic radioecological monitoring to determine the level of long-lived radionuclides in main natural components of the cooling pond.Sampling from the cooling pond, sample preparation, 137Cs and 90Sr concentration measurement in water and aquatic plants as well as interpretation of results are performed in the framework of the State Task of the Institute of Plant and Animal Ecology, Ural Branch of the Russian Academy of Sciences.