Hydrotechnical facilities within the Chernobyl nuclear power plant exclusion zone: impacts on hydrologic regime and plant growth patterns of floodplain water bodies of the Pripyat River

As result of the Chernobyl nuclear power plant accident the territory of the left-bank flood-lands of the Pripyat River have undergone intensive radionuclide contamination. With the purpose of preventing the washing away of radioactive substances, a complex of flood protection dams was constructed. This construction changed the hydrological regime of these territories and caused overgrowth by higher aquatic plants. Absence of a flowing mode of reservoirs, the stagnant phenomena during spring and seasonal high waters on the embank site have caused amplification of eutrophication processes, swamping and, connected with it, increase of water-marsh floristic complex in the structure of the vegetative cover.</jats:p

Long-Term Observations over the Structure of Macrophyte Communities in Floodplain Water Bodies of the Chornobyl Exclusion Zone

The study is based on long-term observations (1998-2021) over the species richness and cenotic activity of macrophytes of floodplain water bodies of the Chornobyl exclusion zone. During this period, the species composition of macrophytes of the studied water bodies remained almost unchanged. The lists of species found in 1998 differ from those registered in 2021 only by three species, including &lt;i&gt;Nymphaea alba, Trapa natans&lt;/i&gt; (registered only since 2007), and &lt;i&gt;Utricularia minor&lt;/i&gt; (found only in 1998, whereas in subsequent years was not observed at all). In the studied water bodies, macrophytes are not diverse in their species composition; their cenotic structure is simple, whereas overgrowing intensity of water surface is high. The presence of rare species of the boreal complex, including primarily &lt;i&gt;Hottonia palustris, Potamogeton acutifolius&lt;/i&gt;, and &lt;i&gt;Callitriche cophocarpa&lt;/i&gt;, makes these water bodies objects of protection and research. In 1998, a common feature of the vegetation cover of all studied floodplain water bodies was a predominance of macrophyte communities, in which the species of river and lake ecosystems, as well as indicator species of increased water logging processes, were registered. At the present time, natural structure of macrophyte communities of floodplain water bodies of the Prypyat River, which was deteriorated as a result of the construction of flood-protection hydraulic structures, is gradually recovered. The peculiarities of the distribution of macrophytes at the present time are indicative of the improvement of water exchange in floodplain water bodies. The chronic ionizing radiation influencing the biota of the studied water bodies for more than 30 years did not result in significant changes in the floristic and cenotic composition of macrophytes. Certain changes are conditioned by changes in hydrological and hydrochemical regime of the floodplain of the Prypyat River. </p

Reconstruction of the absorbed dose of ionizing radiation for helophytes in the water bodies of the near emergency zone at the Chornobyl NPP

Based on modeling the dynamics of the Chornobyl emission radionuclide content in the components of the most polluted reservoirs of the Chornobyl Exclusion Zone, the absorbed dose for helophytes was reconstructed. During the growing season of 1986, the absorbed dose of plants of Glyboke Lake was 78 Gy, Daleke Lake 39 Gy. The absorbed dose rate of plant roots was 2.4 times higher than that of aboveground organs. According to actual data, in the period 2016 - 2019 in the Glyboke Lake average dose of external and internal plant irradiation was about 7.5 mGy/year, and in the Daleke Lake 5.6 mGy/year. On abnormally contaminated sections of the Glyboke Lake, the external dose reaches 0.5 - 1.0 Gy/year. During the period 1986 - 2020, the maximum cumulative (biological) dose of helophytes of Glyboke Lake can be 190 Gy, Daleke Lake 80 - 85 Gy.</jats:p

Temporal variations in mortality from the main causes of death in 2014-2018 in Khanty-Mansiysk Autonomous District-Ugra (Western Siberia)

The aim of this work is to analyze the temporal variations in mortality from the main groups of diseases and external causes in the period 2014-2018 in Khanty-Mansiysk Autonomous Okrug-Ugra (Western Siberia). Methods. Data on mortality wereobtained from the Medical Information and Analytical Center in Khanty-Mansiysk. To test the hypothesis about cyclic variations in mortality, wavelet analysis was applied. Results. Fluctuations in death rates from infectious diseases, neoplasms, mental disorders, diseases of the nervous system and circulatory system, pathology of the digestive system appeared to have a significant circannual rhythm. For diseases of the endocrine system, respiratory system, musculoskeletal and genitourinary system, circannualpattern of mortality was not observed. Mortality from socially significant diseases demonstrate two-year, annual and intra-annual rhythms. Significant rhythms of mortality from injuries with a six-month (p = 0.012) and near-annual (p = 0.045) periods may have an exogenous nature, while circaseptan activity (p = 0.055) seems to have a social genesis. Fluctuations in mortality from suicide occur in near-annual (p = 0.002) and semi-annual (p = 0.068) rhythms. Temporal variations of road traffic accidents are characterized by insignificant six-month and two-week rhythms. Conclusions. Our findings suggest that mortality in the study areahas various duration and number of periods of rhythms, low-energy rhythmic activity with pronounced inter-seasonal and day-to-day fluctuations in weather factors, a changed photoperiodic regime, and seasonal exacerbations of endemic zoonoses against the background of constant exposure to unmodified risk factors for the development of diseases presented in this paper. © 2020, Northern State Medical University. All rights reserved