Speaker
Description
As a result of the nuclear tests conducted in 1949-1989, a difficult radio ecological situation was formed at STS. The greatest contribution to the radiation pollution of this area was made by ground-based and excavated [with the release of soil] nuclear explosions. Among them, the explosions of nuclear bombs in 1949 and 1951, and thermonuclear devices in 1953 and 1956 stand out in terms of the number of radionuclides released into the environment and the excavation explosion of 1965.
During the atmospheric nuclear tests, numerous funnels, trenches, embankments and wreckage of metal, concrete and plastic structures were formed. The surface of the soil in the epicenter of explosion turned into a yellowish-green glassy mass. Through forty years on many sites have survived glassy mass spots of various sizes (1x3m; 3x5m; 10x20m) and shapes occupying up to 30-40% of the area. The power exposure dose (MED) of gamma radiation on these spots reaches 8200-10800 μr/hr. Single specimens of Artemisia frigida pierce through the glassy mass. These plants are formed as flattened cushions 3-15cm in diameter. They do not develop generative organs. On those areas where the vitreous mass has already been destroyed, the MED of gamma radiation reaches 6250-7800 μr/hr. Here incised groupings composed of Stipa sareptana, Festuca valesiaca, Artemisia scoparia are forming. At MEDs of gamma irradiation of 6000 to 7000 µR/h, dissected groupings folded from Kochia sieversiana, Artemisia scoparia developed. At MED gamma irradiation of 3600 to 4500 µr/h, groupings from Artemisia scoparia, Lepidium latifolium were noted. At a distance of 200 m from the epicenter of nuclear explosions, the MED of gamma radiation decreases to 800-1500 μr/hr. Here dominate dissected procenoses layered with turf grasses (Festuca valesiaca, Stipa sareptana) and semi-shrubs (Artemisia frigida). At MED gamma irradiation of 80-200µr/h, groupings of plants develop in composition and structure close to the zonal communities. They are composed of Sareptana Stipa, Festus valesiaca, Artemisia frigida. Only on plots with background values of gamma radiation (18-25 µr/h) communities with predominance of Stipa sareptana, Festuca valesiaca, Artemisia frigida are forming.
On January 15, 1965, the Atomic Lake was formed as a result of an underground explosion at the mouth of the Shagan River. Currently, the blast funnel is filled with water and connected by a flow with the Shagan River, which flows into the Irtysh. The lake is surrounded by debris. On tailings, the MED level of gamma radiation ranges from 400 to 14,000 μr/hr. The height of the depressions around the lake reaches 25-30m, their width in the northern part is about 800 m. Around the lake stretches a beach strip 1-2m wide. She is not mastered by higher plants. Here the MED of gamma irradiation was 500 μR/h. Single plants of Aeluropus littoralis and Phragmites australis were noted within 3-5 m of the water cut at MED 1000 μR/h. With removal from the water cut, at a distance of 6-8m, disconnected groupings of mesophytes Phragmites australis, Calamagrostis epigeios and Elytrigia repens appear at MED of gamma irradiation 1200 μR/h. Single plants and dissected groupings of Atraphxis frutescens, Lagochillus pungens are formed on the middle part of the inner slope of the tailings at MEDs ranging from 1800 to 2200 μR/h. The top of the range is not dominated by vegetation. The MED here reaches 1700 μR/h. The tops, and steep slopes of steep drop offs are not overgrown with vegetation. Only occasionally there are single specimens of Atraphahis frutescens. Here the MED varies between 1400-1700 μR/h. The upper part of the outer slope of the dip is occupied by unformed groupings with Limonlum suffruticosum, Atraphaxls frutescens predominance at MED 900-2400 μR/h. On the middle part of the outer slopes of the tailings, in addition to these species, weedy species of Artemisia sieversiana, A.scoparia, and Kochia sieversiana occur at MED 1000-2700.
