Database of the results of radioecological monitoring of contaminated agricultural lands of the Tula NIISH

For the radioactively contaminated territory of the Tula Research Institute of Agriculture, a database has been created for storing spatially oriented information. The created database contains information about the location of agricultural areas; crop rotation structure; distribution of values of specific activity of 137Cs on agricultural lands; agrochemical indicators of soils of agricultural territories (content of humus, potassium, phosphorus, acidity); soil types; relief. It also contains a calculation module for assessing the content of 137Cs in crop and livestock products. The accumulated data array will be used for designing adaptive landscape farming systems using information on the 137Cs content in the soil generalized over a long-term period.

Radioecological monitoring of the area surrounding the Leningrad NPP: results evaluation

The paper presents results of long-term monitoring of radioecological situation in the area sur-rounding the Leningrad NPP (LNPP), that covers the periods before the Chernobyl accident (1980-1985), during and immediately after the accident (1986-1992) and the late period (2013-2014). After the Chernobyl accident the enhanced radioactivity level in the environment including soil and vegetation was registered in the area surrounded the Leningrad NPP. Several test points for sampling were selected inside the 30-km zone around the LNPP. Before the accident, in 1985, 137Cs soil contamination density was 3 kBq/m2; immediately after the accident, in 1986, the contamination density increased by 10 fold. In the late period, in 2013, the 137Cs soil contamina-tion density reduced significantly, however it exceeded the levels registered in 1985 by 2.6-7.3 times. 90Sr soil contamination density was 1.4-1.6 kBq/m2 both before and after the accident (1985-1992). The presence of artificial radionuclides in agricultural produce before 1985 was caused by global radioactive fall-outs, however no radionuclides emissions from the Leningrad NPP were registered. Average 137Cs content in grain and intertilled crops exceeded their content before 1986 by 19-44 times; the high content was associated with the contamination of the vege-tation by airway. The 137Cs content in agricultural produce is still higher than the level registered before the Chernobyl accident by 1.4-2.1 times, but the current levels are many times less than the current acceptable level. The levels exceeding the acceptable magnitude are found in wild berries only, that grow in some swampland with 137Cs soil contamination density of 3-9 kBq/m2 near the LNPP. Dynamics of transfer factors of 90Sr and 137Cs from soil to agricultural produce in the LNPP area was evaluated. The soil properties and the Chernobyl fall-out are shown to affect the factor magnitude. Presented data demonstrate that the Leningrad NPP operating in the standard way does not influence strongly on radiological situation in the 30-km zone around the NPP.

Comprehensive radioecological monitoring of freshwater ecosystems in the vicinity of Rooppur NPP (People's Republic of Bangladesh)

The paper presents experience of developing and maintaining a system of radioecological monitoring of freshwater ecosystems in the vicinity of Rooppur Nuclear Power Plant (Bangladesh). Components of freshwater ecosystems in the zone of NPP impact are both very informative for determining the environmental state and very important for conducting economic activities. Therefore, the issue of assessing and predicting quality of freshwater ecosystems in the vicinity of NPP is relevant for ensuring radiation and environmental safety. During the studies, we developed a detailed monitoring program; selected observation points for the state of surface water and groundwater at different distances from Rooppur NPP; determined monitoring objects (water, bottom sediments, higher aquatic vegetation, and fish), list of parameters to be studied, observation regulation, methods, and regulatory and technical support. Among the indicators controlled we considered the following ones: physicochemical properties of water and bottom sediments; radionuclide content of components of freshwater ecosystems including natural (40K, 226Ra, and 232Th) and technogenic (90Sr, 137Cs, and 3H) radionuclides; and content of 19 heavy metals, as well as chemical pollutants. Monitoring studies were conducted in 2014–2017, considering climatic peculiarities of the region at different periods of the year. Radionuclides in environmental objects were determined by spectrometry and radiochemistry; heavy metals – by atomic absorption and plasma emission analysis methods. It was established that higher aquatic vegetation in the Padma River is found not in all seasons. In December, it was almost absent. The maximum species diversity was registered in June. Differences between surface water and groundwater in the vicinity of Rooppur NPP were distinguished for several physical and chemical characteristics. Values of drinking water total mineralization and hardness were higher than that of surface water by 2–3 times. This is due to Padma River water composition, the basis of which is meltwater and rainwater. Organic pollutants content in surface water and groundwater was below detection limits or at minimum ones (benzopyrene – less than 0.01 μg·L−1; phenols – 1.3–3.5 μg·L−1; and petroleum products – 0.01–0.043 mg·L−1). Activity concentration of 137Cs in Padma River water did not exceed 0.18 Bq·L−1 (with a mean of 0.07 Bq·L−1) during the observation period. The content of 90Sr was 0.02–0.12 Bq·L−1, and the concentration of 3H varied in the range of 0.8–2.1 Bq·L−1. Mean specific activity of 90Sr in bottom sediments was 0.5–1.8 Bq·kg−1, and 137Cs – 0.8–2.1 Bq·kg−1. Specific activity of 3H in bottom sediments was less than 3 Bq·kg−1, except for 3 samples in 2017 (12–30 Bq·kg−1), which was most likely due to a local pollution. Specific activity of 90Sr in higher aquatic vegetation was 0.4–3.9 Bq·kg−1, and 137Cs – 0.4–1.0 Bq·kg−1. In drinking water, activity concentrations of radionuclides were as follows: 137Cs – 0.03–0.27 Bq·L−1; 90Sr – 0.01–0.16 Bq·L−1; 3H – 0.4–1.2 Bq·L−1. Specific activity of 90Sr in fish was 0.02–1.6 Bq·kg−1.The content of 137Cs in fish was 0.26–0.3 Bq·kg−1. Analysis of monitoring data on heavy metal levels in components of freshwater ecosystems in the vicinity of Rooppur NPP showed that for a number of elements their increased concentrations were recorded, most of which belong to monsoon season. In Padma River surface water, a repeating increase in As, Cd, Mn, and Al concentrations was noted, and in bottom sediments – an increase in As, Cd, Ni, Co, and Zn content, which was associated with anthropogenic impact and increasing runoff of pollutants during monsoon rains. Repeatedly increased As and Mn concentrations were noted in drinking water of Rooppur NPP 30-km zone. In separate samples, there was an increase in Fe and Al content. This might be due to both natural peculiarities of the region (relatively high As content in aquifers) and the state of water supply systems. Obtained results and developed network of radioecological monitoring of freshwater ecosystems would make it possible to register a change in the situation and to identify impact of Rooppur NPP operation on human population and the environment.

The analysis of radioecological monitoring results in the vicinity of the Kursk Nuclear Power Plant

The research presents the data of long-term observations of the impact of the Kursk Nuclear Power Plant operation on the radioecological situation in the region of its location. The dynamics of the content of natural and artificial radionuclides in the components of agricultural ecosystems was studied due to the data based on the information from the radioecological monitoring network developed in 2003. Samples of soils, agricultural products and animal feeds were taken at 11 control sites located on arable lands and grasslands in the vicinity of the Kursk Nuclear Power Plant, and, in settlements, locally produced food was sampled. It was shown that for the period of studies of 2003-2019, the average specific activity of 90Sr in the soils of agroecosystems of the 10 km influence zone of the Kursk Nuclear Power Plant varied within 2.7-4.3 Bq/kg, and specific activity of 137Cs was 14.6-40.8 Bq/kg. At the same time, there were found no trends of increase in the content of artificial radionuclides in soil over time and at different distances from the NPP, and the increased specific activity of 137Cs in soil compared to the global background is explained by the Chernobyl fallout. The variability of the average content of natural radionuclides in the soil for 40K was 481-625 Bq/kg, 226Ra – 20.6-29.5 Bq/ kg, 232Th – 28.2-39.2 Bq/kg, which corresponded to all-Russian data. The average specific activity of 90Sr in grain was 0.24-0.43 Bq/kg, and 137Cs – 0.19-0.37 Bq/kg. Even the maximum levels of artificial radionuclides in grain were 44 times for 90Sr and 85 times for 137Cs lower than the current SanPiN standards. The highest specific activity values of 137Cs and 90Sr in potatoes, vegetables, and gourds were 160 times lower than the SanPiN standards. It was noted that the maximum content of 90Sr in milk was more than 540 times lower than the SanPin standard, and for 137Cs this difference was 330 times. The maximum content of 137Cs in beef turned out to be over 850 times lower than the SanPiN standard for this radionuclide. About 70 Bq/a of 90Sr and 200 Bq/a of 137Cs enter the population diet with locally produced food, which is almost 400 times for 137Cs and 200 times for 90Sr lower than the annual limit. Milk (46%), meat (31%), potatoes and vegetables (14%) make the main contribution to the formation of the internal dose from agricultural products containing 137Cs, and contribution to dose from 90Sr is made by milk (14%) and crop products (potatoes, vegetables, bread) – up to 78%. In general, we concluded that over the past 17 years, the operation of the Kursk Nuclear Power Plant did not lead to a deterioration of the radioecological situation in the region of its location, because during the survey period there was no significant increase in the content of artificial radionuclides in agricultural products, foods and environmental components.

Does Salinity Affect the Distribution of the Artificial Radionuclides 90Sr and 137Cs in Water of the Saline Lakes? A Case of the Crimean Peninsula

In the framework of radioecological monitoring, the features of the distribution of the post-Chernobyl nuclear power plant (NPP) accident artificial radionuclides of 137Cs and 90Sr in the Crimean saline lakes were studied. Samples were collected from 12 Crimean lakes with a salinity range from 2 to 400 g/L in 2014–2017. Concentration of 90Sr varied from 5.9 to 313.6 Bq/m3, and 137Cs from 0.8 to 106.7 Bq/m3. Closing of the North Crimean Canal resulted in a decrease in radionuclide concentration in the lakes. About 61% of the total variability of 90Sr and 33% of 137Cs in lake water can be explained by salinity changes. The salinity affects the behavior of radionuclides in water, mainly influencing their solubility, on isotope exchange between the solution and bottom sediments, and also, probably, through its influence on accumulation of isotopes by aquatic organisms. Salinity is not the alone factor determining the behavior of radionuclides in the lakes, it only acts by interacting with other factors.

Improving radio-ecological monitoring of potentially radon-hazardous territories

Radioecological monitoring of radon-hazardous territories in residential and public buildings of the towns of Lermontov (Russia, Stavropol Region) and Baley (Russia, Transbaikal Region) made it possible to reveal that the volume activity of radon in premises on 1 floor of buildings reliably characterizes the radon inflow from the soil surface. This control parameter, which can be used to estimate the radon danger of the territory, to make decisions on the sanitary condition of the building, to estimate the potential danger to the population or personnel, to calculate the potential dose rates. Improvement of radio-ecological monitoring in potentially radon-hazardous areas is aimed at monitoring the volume activity of radon on 1 floor of buildings, the excess of which is higher than the normal values is the basis for making managerial decisions to protect the population or staff.