Speaker
Description
The combined study of the flora of the newly formed technogenic core ecotopes of experimental plots (EP) of the Semipalatinsk Test Site (STS) and radioecological conditions revealed the differentiation of species at different levels of ionizing radiation. We have determined the radioecological range of growth of 530 species of vascular plants of EP STS. Power of exposition dose (PED) of gamma-irradiation at a level of 5 cm from the soil surface was measured by radiometer SRP 68-01. The level of radioactive pollution is also controlled by dosimeter RKSB-104. Three measurements of gamma-irradiation PED are being made.
Then, a data bank was compiled for each of the 530 species, including the ranges of the MED, the occurrence and the nature of the habitat.
Currently, there are no generally accepted standards for assessing the sustainability of environ- mental facilities to radionuclide contamination. Therefore, to assess the radioecological range of plant growth, i.e. to identify the radioresistance of species, we adopted as criteria the standards of contamination of human skin and clothing established by NRB- 96 RK According to the "Radiation Safety Standards RK, 1996”:
1) the exposure dose rate of gamma radiation is divided into background doses (10-20 μR/h); 2) relatively harmless to biological objects (20-60 μR/h);
3) potentially dangerous (60-3000 μR/h);
4) dangerous (3000-6300 μR/h);
5)especially dangerous (>6300 μR/h).
Plants with high radioresistance, growing at an PED of over 6300 μR/h, are represented by the following species: Artemisia frigida, Chamaenerion angustifolium, Ephedra distachya, Festuca valesiaca, Kochia scoparia, Lotus angustissimus, Phragmites australis, Psathyrostachys juncea, Silene suffrutescens, Stipa sareptana, Typha angustifolia. Currently, 11 species have been identified or 2.1% of the total number of species.
There are already more plants living in man-made ecotopes with an EDR of 2900-6300 μR/h -59, or 11.1%. They are represented by such species as: Artemisia scoparia, Dianthus rigidus, Iris scariosa, Kochia sieversiana, Lepidium latifolium, Limonium suffrutescens, Rumex confertus, Salix cinerea, Sanguisorba officinalis, Stipa capillata, Urtica urens etc.
Plants growing at "potentially dangerous" doses in the range from 60 to 3000 μR/h are divided into groups up to 200 μR/h, 1000 μR/h, 2000 μR/h and 3000 μR/h. This is the largest group (389 subspecies, 73.4%), including such species as Atriplex cana, Tanacetum achileifolium, Gypsophila paniculata, Urtica cannabina, Acroptilon repens etc.
