Download ABSTRACT FORM

EFFECTS OF IONIZING RADIATION ON POPULATIONS
AND ECOSYSTEMS
Geras'kin S.A.,1 Alexakhin R.M.,1 Oudalova A.A.1,2
1
Russian Institute of Radiology and Agroecology, Obninsk, Russia
2
Obninsk Institute of Nuclear Power Engineering, National Research Nuclear University
“MEPhI”, Obninsk, Russia
Release of radionuclides into the environment as a result of human activity is a new
evolutionary factor which creates the risk of additional exposure of all living organisms,
including mans. Responses of populations and ecosystems to low and high doses of
ionizing radiation as well as to radinouclide contamination are discussed in this
contribution. Typical reactions of ecosystems to high dose irradiation such as reduction
in species diversity, changes in species dominance, decline of productivity and
alterations in community structure are considered. Absorbed doses form differently in
case of acute irradiation and in the course of large radiation accidents. There are
essential differences in absorbed doses for humans and typical biota representatives in
the same radioecological situation. Particular attention should be paid to the
phenomenon of radioadaptation, changes in sex, age and genetic structure of
populations since such effects cannot be reduced to the basic mechanisms of biological
action of radionuclides. The results of field studies carried out on different plant species
(winter rye and wheat, spring barley, oats, Scots pine, wild vetch, crested hairgrass) in
various radioecological situations (nuclear weapon testing, the Chernobyl accident,
uranium and radium processing) are discussed. Populations growing in areas with
relatively low levels of pollution are characterized by the increased level of both
cytogenetic alterations and genetic diversity. Contamination of the plants environment
activates genetic mechanisms, changing a population’s resistance to exposure. However,
there are ecological situations where enhanced resistance has not evolved or has not
persisted. Experience gained in many studies allows to list main challenges of up-todate radioecology: analysis and formalization of mathematical models of key processes
determining the migration of radionuclides in major natural environments; development
of dosimetry models for reference biota species; analysis of the mechanisms underlying
the formation of radiobiological effects at different levels of biological organization from molecular to the ecosystem, especially in conditions of chronic radiation exposure;
development of a unified system of radiation protection of man and the environment
that is compatible with the risk assessment of chemical pollutants.