Page on foundation of agricultural radioecology
Agricultural radioecology is the branch of knowledge which studies the regularities of radionuclides migration in biological chains and action of the ionizing irradiation on agricultural crops and animals. Applied purpose of the science consists in elaboration of measures constricting the radionuclides involvement into biological rotation, permiting reduction of radioactive substances content in plants and animals, and , hence, in crops and animal production. In general, it can be considered as substantiation for conducting and functioning of the farming industry in territories with the increased content of radioactive substances.
Investigations in agricultural radioecology became especially important when atomic energy began to be used in various branches of national economy. In general, human irradiation by technogenic radionuclides consists from:
Internal irradiation plays the main role in formation of the dose loading on human. Therfore radionuclides entry to human organism with the foodstuffs attracted the exclusive attention to the problems of agricultural radioecology.
It is very complicated to decrease the part of external dose of irradiation (de-activation of territories, paving of roads and footways with asphalt, central water supply, gasification etc.). At the same time countermeasures aiming decrease of the radionuclides intake by human organism with foodstuffs have been elaborated and scientifically substantiated, they can be considered as the most important in a complex of radioprotective measures.
Several stages can be defined in a progress of agricultural radioecology. Studies on accumulation of heavy natural radionuclides- 238U, 226Ra, 232Th etc. by plants and their peculiarities were of a special interest during pre-war years. The interest was connected mainly with elaboration of the biolgeochemical method in uranium search, and studies of regularities of heavy metals uptake by plants. At the same time the first studies on the action of the increased natural radiation background on plants populations have been carried out.
The second stage of agricultural radioecology progress is bound with the nuclear tests in atmosphere in 1950-60 s entailed by fallout of a lot of artificial radionuclides included into the biological rotation in plants, animals and human. Just in that time agricultural radioecology was formed as an independent scientific discipline within its modern structure.
During global monitoring of the environment contaminated with the radioactive fallouts after nuclear tests carried out in these years, regularities of migration of such fission products as 137Cs and 90Sr (main long-living artificial radionuclides contained in a mixture of fission splinters ), peculiarities of accumulation of plenty of fission products, radionuclides with induced activity and some trans-uranic radionuclides in plants have been studied. Parameters of metabolism of these radionuclides in organism of the agricultural animals were estimated; parameters of artificial radionuclides accumulation in plant and animal products were estimated. These results became the base for determination of the dose loadings on population and impartial analysis of consequences of the biosphere contamination with radioactive fallout after nuclear tests.
The last stage of agricultural radioecology progress falls at the end of 60s - beginning of 70s. It is the period of intensive growth of nuclear energy engineering and radiation technologies usage in various branches of national economy. It became clear then that nuclear power had to be one of the main issue in a nearest future, supplying the growing power demands of people, on the one hand, and that the general progress in nuclear power development depends on solution of the ecological problems of the environment protection from radiation influence connected with the complete nuclear fuel cycle (NFC), on the other hand. It should be noted that at all the stages of NFC, beginning from the extraction of uranic ore till the processing of the used fuel and burial of high active wastes, artifical radionuclides are released into the environment , including agricultural sphere, and heavy natural radionuclides migration speeds up, including agricultural chains of the rotation. Thus, resolution of the ecological safety problem on the functioning atomic power stations and all enterprises of NFC in total is strong connected with analysis of the radiation state in agroindustrial sphere on the territories bordering upon the enterprises of NFC, and at the accidental cases with following application of measures limiting radionuclides uptake by agricultural production. It is bound with the fact that radionuclides accumulation in foodstuffs in the majority of the radiological situations can be the main addition issue of human exposure.
Problems of agricultural radioecology became especially actual in the emergency cases, when radioactive substances are ejected into the atmosphere. Such situations were observed at the South-Ural accident in 1957 when the can with radioactive wastes exploided; at the radiation accident in Windscale (Great Britain) in 1957; at the Chornobyl NPP accident in 1986. Countermeasures in agriculture, directed to limitation of the radionuclides uptake by human organism, can be regarded in such cases as the main in a measures package on radiation protection supply . Thus, the prior role of agricultural production contaminated with radionuclides in formation of the total population dose of irradiation is shown.