Influence of Chronic Radiation Exposure on the Temporal Dynamics of Seeds Germination in Scots Pine Populations from the Bryansk Region Affected By the Chernobyl Accident

Temporal dynamics of seeds germination in Scots pine populations growing in theBryansk region of Russia radioactively contaminated as a result of the Chernobyl accident were investigated over a period of 8 years (2008-2015). In contrast to cytogenetic effects in Scots pine, we failed to detect any significant impact of chronic radiation exposure on time dynamics of seeds germination. Keywords: Scots pine, Chernobyl accident, chronic exposure, temporal dynamics, seeds germinatio

ALTERATION OF ACTIVE SUBSTANCE CONTENT IN "HEXACHLORAN DUST" PESTICIDE FORMULATION AT EXPOSURE TO ELECTRON BEAM

The most popular methods of organochlorinated pesticides (OCP) destruction, which are based on thermal dechlorination, are not ecologically safe. The other process – radiation-chemical degradation – has got some advantages. It does not involve high temperatures and expensive reagents. In this study, the effective OCP degradation was observed under irradiation of residuals of the active substance of ‘Hexachloran dust’ pesticide formulation, intended for utilization. Parameters for the preparation powder (dry form) exposure to electron beam are discussed. It is shown that at the exposure to electron beam at dose of 100 kGy, the degradation degree of hexachlorocyclohexane (HCH) isomers in a composition of active substance achieves 56.2–66.3%

Study of the Effect of Radiation Dose Rate on the Stability of Various Organochlorine Pesticides

Abstract irradiated at dose of 10 kGy with dose rate varied from 8.3 ⋅ 10−3 up to 2.33 Gy/sec. It is found that the shape of the degradation degree relationship on dose rate is similar for different OCPs in polar and non-polar solvents (hexane, 2-propanol) and does not depend on the concentration of initial substance. The maximum of the OCP degradation degree is registered in the dose rate range of 0.23-0.43 Gy/sec. A lognormal distribution is considered as a function best fitting the experimental data. The OCP degradation mechanism could be explained by the ratio of active and recombined particles along the gradient of ionizing radiation intensity. Keywords: organochlorinated pesticide; irradiation, dose and dose rate of gammaradiation; radiation degradation; functional dependenc

Radiological Problems of Tritium

In light of the session documents (UNSCEAR, 2015, 2016), presented are the results of health risk assessment in drinking water containing tritium as well as results of field observations and bioassay with algae (Lemna minor and Polyrhiza) from water bodies near radiation-dangerous industrial and scientific objects. The prospects for future studies in these areas should be associated with the assessed human radiation dose from organically bound tritium in organs and tissues of people, animals and plants; the search for plants and animals selectively accumulating tritium and its subsequent bioassay in water. It is necessary to develop the approaches to harmonization of tritium standards in water objects and potable water, in particular. Sanitary and hygiene standards are suggested to develop on the basis of health risk assessment in drinking water with tritium. The upcoming trend for assessing the contribution of organically bound tritium to the total human radiation dose is the local irradiation by tritium incorporated into DNA of cells and tissues and radiosensitive organs. The well-known and new methods of microdosimetry of DNA incorporated radionuclides are necessary to solve this problem

To Breve fra Niels Krog Bredal.

The present work has been done within the IAEA Environmental Modelling for Radiation Safety Programme. EMRAS-II aims to improve the capabilities in the field of environmental radiation dose assessment by means of acquisition of improved data for model testing, comparison, reaching consensus on modelling philosophies, approaches and parameter values, development of improved methods and exchange of information

Cytogenetic Effects in Pinus sylvestris L. Populations Experiencing Chronic Low Level Radioactive Exposure

Contamination of the environment has become a worldwide problem. A clear understanding of all the dangers posed by environmental pollutants to both human health and ecologic systems are needed. An important gap in our knowledge is long-term ecotoxical effects induced by chronic low dose-rate and multi-pollutant exposure at contaminated sites. Actually, few studies exist that are directly relevant to revealing the responses of plant and animal populations to radionuclides in their natural environments. The results of long-term field studies of cytogenetic effects in Scots pine (Pinus sylvestris L.) populations growing in the vicinity of the radioactive wastes processing and storage facility (Leningrad region, Russia) and in the Bryansk region, Russia affected by the ChNPP accident are presented. Cytogenetic damage levels in root meristem of seedlings are found to significantly exceed corresponding controls. Adaptation processes in the affected tree populations are studied by means of an additional acute exposure of seeds. An enlargement of variance of studied cytogenetic parameters is found in the populations experiencing radiation and technogenic influence. This indicates processes of cytogenetical adaptation in the populations over 30 years experiencing anthropogenic influence. An analysis of the structure of ecological-genetical variability is carried out with the purpose of separating two components in the interpopulational variability the first is engaged to the genetically determined variability of biological characteristics intrinsic for this species, and the second is responsible for the variability originating from anthropogenic contamination of the habitat areal. Changes of these two types of variability in pine populations in the Leningrad region are studied in dependence on time and technogenic impact severity. Our results have provided evidence that genetic diversity is increased in Scots pine populations occupying the radionuclide-contaminated and/or technogenically affected sites

Cytogenetic variability in PInus sylvestris L. populations experiencing anthropogenic influence

Pinus sylvestris L. populations growing at the territory affected by nuclear waste storage facilities were monitored in 1997-2002. Cytogenetic damage levels within root meristem of seedlings significantly exceed corresponding controls. Populations experiencing man-caused influence have a higher seeds radioresistance and enlarged cytogenetic variance. These are considered as an indication of adaptation processes in the studied pine populations. An analysis of the structure of ecological-genetical variability is carried out. Changes of two components of the intrapopulational variance were studied in dependence on time and man-caused impact. The first component is engaged to the genetically determined variability of biological characteristics intrinsic for the species and is dominant in studied tree populations. The second is responsible for the variance originating from anthropogenic contamination of the natural habitat. A tendency of destabilizing dynamics and increasing mean values of intraclass correlation coefficient that is a measure of contribution from heterogeneity among trees into total cytogenetical variability is demonstrated under conditions of chronicle technogenic impact on pine populations

Morphometric Measurements of Scots Pine Needles From Radioactively Contaminated Area

The morphometric indices of needles were investigated in chronically irradiated Scots pine (Pinus sylvestris L.) populations from territories that were heavily contaminated by radionuclides as a result of the Chernobyl Nuclear Power Plant accident. The variability in needle weight and length, as well as the fluctuating asymmetry indices were studied in seven contaminated and two reference populations of Scots pine in 2011, 2013, 2014 and 2016. The weight of needles in the contaminated populations was significantly higher than in the reference population; however, the dependence of this index on the level of radiation exposure was not revealed in the studied range of doses. The length of needles differed significantly from the references populations. The effect changed from decreasing to increasing in various years of observation; however, in 2016 this index decreased with the dose rate of β-radiation. The index of fluctuating asymmetry in needle length was significantly higher than at the reference sites during three years and correlated to the estimated annual absorbed dose in 2011 and 2013. No relationship was revealed between the asymmetry in weight of paired needles and radiation exposure

Plants ecotoxicology. A case of low doses and multipollutant exposure

Results of laboratory, “green-house" and long-term field experiments carried out on different plant species (spring barley, Scots pine, bulb onion and others) to study ecotoxical effects of low doses and concentrations of such common environmental factors as acute and chronic g-radiation, heavy metals, pesticides, artificial and heavy natural radionuclides, are presented. Special attention is paid to ecotoxic effects of chronic low dose exposures, synergistic and antagonistic effects of different factors' combined action. The results of long-term field experiments in the 30-km Chernobyl NPP zone and in the vicinity of a radioactive wastes storage facility are discussed. The data presented suggest that the further evolution of investigations in this field would issue in the development of a theoretical bases and practical procedures for environmental protection against radioactivity, taking into account the new experimentally confirmed facts about the presence of such essentially important singularities as the nonlinearity of a dose-effect relationship, radiation-induced genomic instability, phenomenon of radioadaptation, increased probability of synergetic and antagonistic effects of the combined action of different nature factors

Alteration of Active Substance Content in "Hexachloran Dust" Pesticide Formulation at Exposure to Electron Beam

The most popular methods of organochlorinated pesticides (OCP) destruction, which are based on thermal dechlorination, are not ecologically safe. The other process – radiation-chemical degradation – has got some advantages. It does not involve high temperatures and expensive reagents. In this study, the effective OCP degradation was observed under irradiation of residuals of the active substance of ‘Hexachloran dust' pesticide formulation, intended for utilization. Parameters for the preparation powder (dry form) exposure to electron beam are discussed. It is shown that at the exposure to electron beam at dose of 100 kGy, the degradation degree of hexachlorocyclohexane (HCH) isomers in a composition of active substance achieves 56.2–66.3%