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Description
Underground nuclear tests on Semipalatinsk test site were carried out at the Balapan Experimental Site wells (ES). This 360 km2 site is located in the eastern part of the Semipalatinsk test site. The territory is a gently sloping ancient alluvial, deluvial – proluvial and modern alluvial plain. Vegetation cover – desolate sagebrush-grasses dwarf semishrub-bunchgrass desert steppes (Stipa sareptana, Festuca sulcata, Artemisia marshalliana, A. gracilescens, A. frigida, A. lessingiana) on chesnut light soils, communities of Camphorosma monspeliaca + Artemisia gracilis – on solonetz, communities of Halocnemum strobilaceum + Kalidium foliatum, communities of Halimione verrucifera on solonchaks. On meadows solonchakous soils of the Shagan River, communities are formed composed of Aeloropus littorailis, Salicornia europeae.
The satellite image of the ES “Balapan” shows the beds of the Shagan and Aschisu rivers, the Shagan reservoir, to the north of it are the dumps of the “Atomic Lake”. In the center of the ES is a large salt lake. The Karazhira brown coal deposit is located to the northwest of it. Less noticeable are white lines (roads) and numerous bright dots (epicentric zones around wells).
131 nuclear devices were tested at the Balapan ES in 1968-1989. Underground nuclear explosions were carried out here in vertical wells 500-600 m deep. The explosions were accompanied by the release of soil and the release of volatile radionuclides. In the epicentral regions of 103 wells, the exposure dose rate of gamma radiation does not exceed 15-25 µR/h. Around the mouths of 9 wells, the PED of gamma radiation ranges from 1 500 to 5 000 µR/h. Here, the restoration of the destroyed vegetation begins with the invasion of single individuals of Artemisia scoparia, Kochia Siversiana, and Limonioum suffruticosum. When moving away from the well, vegetation differentiation by microrelief elements is observed. According to micro-elevations at the PED of gamma radiation of 900 µR/h, sparse groupings are formed, composed of Artemisia schrenkiana, A. scoparia, Festuca valesiaca, on flat areas – at the PED of gamma radiation of 1 000 µR/h - Artemisia gracilescens, Stipa sareptana, Festuca valesiaca. According to microdepressions with PED of gamma radiation of 2000 µR/h groupings with a predominance of Stipa sareptana and Festuca valesiaca are formed. At a distance of 9-10 m from the well, no more than 10% of the territory is occupied by plants, at a distance of 20-30 m - 20-25%, at a distance of 30-50 m - 30-40%. At a distance of 50-80 m from the well, the PED decreases to 200 µR/h, and at a distance of 200 m - to 20-25 µR/h. Here the vegetation cover has not undergone noticeable changes.
Various fortifications were built at the Balapan ES. Their ruins are being assimilated by plants very slowly. Currently, groupings of plants with a predominance of Petrosimonia oppositifolia, Ceratocarpus arenarius. On the slopes of the dumps, groups of plants develop with a predominance of Kochia siversiana, Artemsia scoparia. Power lines and many roads are laid on this ES. Depending on the type of soils and their salinity, disturbed vegetation is represented by the following numerous groupings: 1) on chesnut light soils – with a predominance of Festuca valesiaca, Artemisia austriaca, A. marshalliana; 2) on chesnut light solonetzig soils – with a predominance of Artemisia gracilescens; 3) on chesnut light gravelly soils - with a predominance of Artemisia frigida, Ephedra dystachia; 4) on solonetz – with a predominance of Camphorosma monspeliaca, Psathyrostachy junceus.
On January 15, 1965, as a result of an underground explosion with the release of soil in the floodplain of the Shagan River, an “Atomic Lake” was formed. Currently, the explosion funnel is filled with water and is connected by a channel to the Shagan River, which flows into the Irtysh. The height of the dumps around the lake reaches 25-30 m, width – 300-800m. The level of PED gamma radiation ranges from 400 to 14 000 µR/h. The inner dump and the beach strip of the “Atomic Lake”. The beach strip around the lake 1-2 m wide has not been assimilated by plants. Here, the PED of gamma radiation reaches 500 mR\h. At a distance of 3-5 m from the water edge, the PED of gamma radiation increases to 1 000 µR/h. In these conditions, single individuals of Aeluropus littoralis, Phragmites australis appear. At a distance of 6-8 m from the water's edge, the PED of gamma radiation increases to 1200 mR\h. Sparse groupings of mesophyte cereals appear here: Phragmites australis, Calamagrosti epigeios, Elytigia repens. In the middle part of the slopes of the dumps, the PED increases to 1 800-2 200 µR/h. Isolated individuals and sparse groupings of Chondrilla laticoronata, Senecio erudicatum. Steep slopes and tops of dumps are not assimilated by plants. Here the PED reaches 1 400 -1 700 µR/h.
The upper part of the outer slope of the dump is occupied by unformed groupings with a predominance of Lemonium suffruticosum, Artemisia shrenkiana, at a gamma radiation dose of 900-2 400 µR/h. On the saline soils of the dumps, only isolated individuals of Nitraria sibirica and Limonium coralloieds were observed with a gamma radiation PED of 1 500-2 200 µR/h. In the middle part of the outer slope of the dump, isolated individuals of Festuca valesiaca, Artemisia gracilescens were noted with a gamma radiation PED of 390 µR/h. In the lower part of the outer slope of the dump, groupings are formed with a predominance of Festuca valesiaca, Artemisia gracilescens at a gamma radiation PED of 350 µR/h. In the north-western part of the ES “Balapan” there is a brown coal deposit “Karazhyra”. It is being developed in an open way. Coal is exported by rail. The empty rock is formed on the dumps. Currently, only the lower part of the dumps has been assimilated by single individuals and sparse groupings of annual salt pans (Salsora rosaceae, S. collina, S. nitraria) and weed species (Lepidium perfoliatum, Medicago falcata). In small areas, groupings are formed with predominance of dominants of the desert steppes of the adjacent territory– Festuca valesiaca, Artemisia lessingianna. In the erosive depressions of the upper ledges of the quarry, single individuals of Halogeton glomeratus, Salsora rosaceae, Pangeria turkestanika. The lower ledges of the quarry have not been assimilated by plants. Abandoned quarries are filled with water. On the outskirts of reservoirs, groups of hygrophytes are formed – Phtagmites australis, Typha latifolia, Butomus umbellatus.
| Section | Radiation ecology and methods of analysis (Section 3) |
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