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

Contribution for the derivation of a soil screening value (SSV) for uranium, using a natural reference soil

In order to regulate the management of contaminated land, many countries have been deriving soil screening values (SSV). However, the ecotoxicological data available for uranium is still insufficient and incapable to generate SSVs for European soils. In this sense, and so as to make up for this shortcoming, a battery of ecotoxicological assays focusing on soil functions and organisms, and a wide range of endpoints was carried out, using a natural soil artificially spiked with uranium. In terrestrial ecotoxicology, it is widely recognized that soils have different properties that can influence the bioavailability and the toxicity of chemicals. In this context, SSVs derived for artificial soils or for other types of natural soils, may lead to unfeasible environmental risk assessment. Hence, the use of natural regional representative soils is of great importance in the derivation of SSVs. A Portuguese natural reference soil PTRS1, from a granitic region, was thereby applied as test substrate. This study allowed the determination of NOEC, LOEC, EC20 and EC50 values for uranium. Dehydrogenase and urease enzymes displayed the lowest values (34.9 and ,134.5 mg U Kg, respectively). Eisenia andrei and Enchytraeus crypticus revealed to be more sensitive to uranium than Folsomia candida. EC50 values of 631.00, 518.65 and 851.64 mg U Kg were recorded for the three species, respectively. Concerning plants, only Lactuca sativa was affected by U at concentrations up to 1000 mg U kg1. The outcomes of the study may in part be constrained by physical and chemical characteristics of soils, hence contributing to the discrepancy between the toxicity data generated in this study and that available in the literature. Following the assessment factor method, a predicted no effect concentration (PNEC) value of 15.5 mg kg21dw was obtained for U. This PNEC value is proposed as a SSV for soils similar to the PTRS1

Impact assessment of long-term chronic radiation exposure on plant populations

Studies that examine biological effects on non-human biota in natural settings provide a unique opportunity for obtaining information about the potential biological hazard associated with radioactive contamination. The results of long-term field study in the Bryansk Region, Russia, affected by the Chernobyl accident are discussed. Plant populations growing in areas with relatively low levels of pollution are characterized by the increased level of both cytogenetic alterations and genetic diversity. In particular, radioactive contamination of the plants’ environment activates genetic mechanisms, changing a population’s resistance to exposure. However, there are radioecological situations where enhanced radioresistance has not evolved or has not persisted. A development of a system for protection of the environment from ionizing radiation should be based on a clear understanding of these effects and their contribution to response of populations