EFFECT OF SOIL TREATMENT ON CESIUM-137 ACCUMULATION IN FLOWER POLLEN AND IN ITS PROCESSING PRODUCTS BY HONEY BEES

Abstract

Over the past few decades, the level of radiation has significantly increased due to artificial sources – radionuclides. In particular, the Chernobyl accident led to the release of about 50 million Кі of various types of radionuclides into the environment. As a result of the accident at the Chernobyl nuclear power plant in Ukraine, a large number of territories of the Zhytomyr region are polluted – 50%, Kiev – 26%. About 26% of the contaminated area falls on the Chernigov, Rivne, Sumy and Volyn regions. The radioactive substances that were part of the nuclear fuel were concentrated in the environment, from where they partially migrate along the soil-plant-living organisms chain, causing a number of negative changes in them. Immediately after the Chernobyl accident, iodine-131 posed a great danger to living organisms; its radioactivity in the contaminated area was 7.3 MКi. Iodine-131 is a beta and gamma emitter with a half-life of 8.04 days. This element is characterized by high activity in the soil-plant-production-organism system. It enters the body by the oral route and accumulates mainly in the thyroid gland. At the same time, cesium-134, cesium-137 and strontium-90 are also dangerous for living organisms, the share of which is about 3% of the total radioactivity. All other radionuclides that were released into the environment during the Chernobyl accident are less dangerous due to the low rate of entry into living organisms. Cesium-137 has a half-life of 30.2 years and is absorbed into the body in three ways: percutaneous, aerial and oral. The largest proportion of cesium-137 is ingested orally. It is a chemical analogue of potassium and is actively involved in the metabolic process. Therefore, it can accumulate in high amounts in body tissues. About 10% of cesium-137 is excreted from the body with indigestible food residues, and the vast majority - with urine. Cesium-137, penetrating into the body, is concentrated mainly in muscle tissue, and comparatively less in bone tissue. It is excreted from bone tissue much more slowly than from muscle tissue. Now in the environment there is still about 50% of cesium-137, which got into the environment as a result of the Chernobyl accident. Radionuclides in the soil are in a moving state, therefore they move to certain layers of it. The speed of such movement of radionuclides in the soil depends on its properties, the content of mineral and organic substances. In particular, it was revealed that the migration of cesium-137 on mineral sod-podzolic soils is ten times lower than on peat and peat-bog soils. This is typical of the soil of the ecological zone of Polesie. The composition of the soils of this zone includes no more than 1.0% of clay, 0.8-1.2% of humus, 3-5% of the silty fraction, causing a high migration of radionuclides. Cesium-137 in these soils is in the sod in a fast-moving form and rather intensively migrates into the vegetation. It has been proven that the mineral part and humus firmly fix cesium-137. The accident resulted in about 1,500,000 pollution in Ukraine. Hectares of forests, most of which have lost their practical value and are withdrawn from use. It has been established that the main amount of radionuclides is concentrated in the upper five-centimeter soil layer and in the forest litter, which is characteristic of pine forests. In pine forest stands, 30-60% strontium-90 and 40-80% cesium-137 are concentrated in the litter, and about a third of radionuclides are concentrated in deciduous forests. Most radionuclides enter plants by the root route. Some authors report that sometimes plants accumulate significantly more radionuclides, even with a lower content of them in the soil. This trend is observed in the Polesie of Ukraine. Over the past 15 years, the strontium-90 content in plant products has not changed significantly. Researchers have studied the peculiarities of the accumulation of radioactive substances by melliferous plants, which can actively accumulate cesium-137. Plants of the family Rosaceae, buckwheat, buttercups are classified as active accumulators of radiocesium. A high content of strontium-90 is characterized by silver cinquefoil, caustic buttercup, and such honey plants as red and white clover, alfalfa, horned lily, sainfoin and mouse peas, common heather, blueberries intensively accumulate both cesium-137 and strontium-90. The intensity of accumulation of cesium-137 in bee pollen, perge and homogenate of drone larvae produced by bees from pollen of winter rape, sunflower and buckwheat in different ways was studied.