Speaker
Description
Vegetation mapping of the experimental testing site (ETS) at a scale of 1:50,000 was carried out using combined satellite images (SI): one part obtained by the ETM sensor from the Landsat satellite, and the other part by the LISS sensor from the Ressoursessat satellite. Atmospheric nuclear explosions (30 surface and 87 air), as well as a thermonuclear bomb explosion, were carried out from 1949 to 1962 at the ETS “Experimental Field,” located in the northwestern part of the Semipalatinsk Test Site (STS). Its area is about 302 sq. km.
At the ETS “Experimental Field,” numerous facilities of various purposes were built: a road and railway bridge, a metro station, buildings, an airfield, bunkers, trenches, dugouts, and earth shelters. Communication lines and numerous dirt roads were laid. In the southern part of the ETS “Experimental Field,” craters from several atomic bomb explosions still remain. The SI clearly shows the scale and degree of ecosystem disturbance at the ETS “Experimental Field” as a result of atmospheric nuclear explosions. In the center of the ETS, a light-gray phototone contour is visible. This is the epicenter of several atmospheric nuclear (29.08.1949; 24.09.1951) and thermonuclear (12.08.1953) explosions. At the epicenter of the explosions, in some areas vitrified slag of a greenish-gray color still remains, and the exposure dose rate (EDR) of gamma-radiation reaches 8200–16000 μR/h. In areas with EDR gamma radiation of 14,000–16,000 μR/h, no plants are found. At EDR levels of 10,000–13,800 μR/h, on leveled intermountain plains with radioactive slag, isolated individuals of Artemisia frigida appear in the form of flattened cushions with diameters of 3–15 cm. Generative shoots do not form. With distance from the epicenter, the level of radioactive contamination decreases. At 200 m it reaches 750–1500 μR/h. Here, the number of species in the vegetation cover increases and the spatial structure of coenoses becomes more complex. At EDR gamma radiation of 80–200 μR/h, groupings dominated by Festuca valesiaca and Stipa sareptana are formed. In composition and structure, they are close to zonal communities. To the east, south, and northeast of the explosion epicenter lies a deluvial-proluvial plain. In the SI, it appears in a heterogeneous gray phototone. Against this background, numerous inclusions of light-gray and dark-gray shades are visible. During atmospheric atomic explosions, ecosystems here were severely disturbed: 1. a significant area was occupied by military-technical facilities; 2. surface soil layers were stripped; 3. communication lines and numerous dirt roads were laid; 4. throughout the area, numerous fragments of metal, concrete, and plastic objects are scattered; 5. in 1996–1997, local businessmen organized mechanized extraction of copper cables, leaving many kilometers of unfilled trenches up to 90 cm deep. The displacement of soil layers during cable extraction contributed to secondary ecosystem contamination; 6. large-scale salt harvesting has been carried out at Lake Zhamantuz, and the salt is exported for sale to the population. As a result of the above anthropogenic factors, at EDR gamma-radiation levels of 20–200 μR/h, sparse plant groupings are formed here, consisting of ruderal annuals and biennials (Kochia siversiana, Artemisia scoparia), turf grasses (Festuca valsesiaca, Stipa sareptana), and dwarf shrubs (Artemisia frigida, Ephedra distachya). For the northeastern, eastern, and southeastern parts of the ETS “Experimental Field,” low-hill terrain is characteristic. In the SI, it appears in a distinct black phototone. During nuclear tests, the hilly terrain was significantly disturbed by the construction of underground communications with stone embankments 0.4 m high and up to 1 m wide. On stone embankments of military-technical facilities (observation posts, warehouses, etc.) at EDR 20–650 μR/h, coenoses are formed dominated by Artemisia scoparia, Ceratocarpus arenarius, Ephedra distachya, Psathyrostachys juncea, Festuca valesiaca, Koeleria cristata. On the deluvial-proluvial plains of the western, southwestern, and northwestern parts of the ETS, small areas of rocky hills are located. In the SI, they are displayed in dark-gray phototone. The rocky hills were significantly disturbed during atmospheric tests: 1. numerous trenches; 2. dugouts; 3. craters from explosions; 4. numerous metal, plastic, and concrete fragments from destroyed engineering structures. Hilltops with exposed bedrock and explosion-disturbed areas (without vegetation) appear as light spots in the SI, while explosion craters appear as dark tones. In disturbed areas, syngenesis at EDR gamma radiation 45–50 μR/h begins with isolated individuals of the ruderal plant Setaria viridis and sparse groupings of Festuca valesiaca and Stipa sareptana.
In the northwest and southwest of the ETS “Experimental Field,” lake basins, intermountain saline depressions, and basins of drying lakes are located. In the SI, they appear as pale bluish-gray phototones. Anthropogenic disturbance of that territory is caused, in addition to chronic ionizing radiation, by the construction of military-technical facilities (trenches, dugouts, ditches). Here, on meadow soils, meadow solonchaks, and solonchaks, communities of mesophytes (Hordenum brevisubulatum), halomesophytes (Puccinellia dolicholepis) and halophytes (Halimione verrucifera) are formed.
