After some time following the global depositions and pollution after the Chernobyl NPP accident, Lithuanian soils are most contaminated with 137Cs and 90Sr. In the work the 137Cs accumulation as well as vertical and horizontal migration in soil have been evaluated. The specific activity of the artificial origin 137Cs in tree segments has been determined, coefficients of its transfer from soil to various parts of the woody plant have been evaluated and compared with the transfer of the natural origin radionuclide 40K. The radionuclide accumulation both in soil and plants, wash–out from the environment and radioactive decay last for years, therefore it is expedient to choose proper methods and evaluate tendencies of the long–term contamination variation. Radionuclides having penetrated into the environment are accumulated in the vegetative ground cover and upper soil layer. Their accumulation in plants occurs directly from the atmosphere through their above–ground parts, while from leaves, branches and sprays as well as root surface radionuclides get into plant tissues and join the biological metabolism. These processes have not been evaluated sufficiently yet, though it is important from both biological and environmental point of view. After evaluating the radionuclide penetration into trees through their above–ground part and roots, radionuclide accumulation and distribution in a tree can be modeled and forecasted as well as a reverse task can be solved – their volume... [to full text]

General Characteristic of the Disertation The problem The development of mankind is inevitably related to the ever increasing impact on nature. During recent decades due to scientific and technical advances, human possibilities of influencing the nature began to substantially exceed our ability to understand, evaluate and forecast consequences of this activity, quite often unexpected and unacceptable. With the nuclear technology development, along with other problems there occurred the problem of the environment contamination with radioactive substances. Their consequences are felt over many years, and radionuclides having penetrated into the environment take part in the exchange processes between various natural media, migrate over long distances, get into biological objects and accumulate in them. Previously, especially after the Chernobyl nuclear power plant (NPP) accident, and currently most attention both in the world and in Lithuania is paid to the investigations of specific activity of radioactive substances in the environment. However, there are a lot of problems of evaluating their biological danger, accumulation, migration and withdrawal in the environment from different environmental objects as well as of forecasting these processes. From the atmosphere radioactive substances are withdrawn with dust, they can be washed out with precipitation and decrease during radioactive decay. Radionuclides deposited to the ground surface are absorbed by soil and vegetation... [to full text]

Pasyviųjų priemaišų jūrinėje aplinkoje įvertinimas ypač svarbus gamtosauginiu aspektu. Ypatingas dėmesys skiriamas Baltijos jūros ekologinei būklei, kurią lemia jūros dubens ypatybės, silpnas ryšys su Pasauliniu vandenynu, klimatinės ir hidrometeorologinės sąlygos. Pastaraisiais dešimtmečiais jūros baseine didėja antropogeninės kilmės teršalų kiekis. Branduolinės fizikos ir technikos plėtra neišvengiamai sukelia technogeninės kilmės radionuklidų patekimą į jūrinę aplinką. Daug dėmesio skiriama 137Cs radionuklidui, nes iki šiol jūros vandens tyrimai rodo aukštas šio radionuklido tūrinio aktyvumo reikšmes. Be to, 137Cs radionuklidas geras indikatorius, tiriant kitų pasyviųjų priemaišų migraciją Baltijos jūros vandenyje. Daug mokslininkų nagrinėja problemas, susijusias su technogeninės kilmės radionuklidų kiekiais, jų sklaida ir poveikiu jūrinei aplinkai. Tačiau darbų, kuriuose būtų nagrinėjama radionuklidų tūrinių aktyvumų pokyčių bei pernašos Baltijos jūros priekrantės vandenyje problema, praktiškai nėra. Atsižvelgiant į tai, šiame darbe nustatytas 137Cs radionuklido tūrinis aktyvumas Baltijos jūros Lietuvos priekrantės paviršiniame vandenyje bei įvertinti hidrometeorologiniai parametrai. 137Cs radionuklido tūrinis aktyvumas Baltijos jūros vandenyje nėra pastovus, todėl aktualu parinkti tinkamus nustatymo metodus ir vertinti jo pokyčių tendencijas. Įvertinus radiocezio tūrinio aktyvumo pokyčius priekrantės vandenyje, galima modeliuoti ir prognozuoti taršos šaltinio atsiradimo... [toliau žr. visą tekstą] / The evaluation of the passive admixture transfer in the marine environment is very significant from the point of view of environmental protection. A particular attention is devoted to the Baltic Sea ecological state, which is strongly influenced by the peculiarities of the sea bottom, weak connection with the World Ocean, climatic and hydrometeorological conditions. During the recent decades, the tendency of increment of the amount of anthropogenic pollutants is observed. The development of nuclear energetics and technology inevitably causes the spread of radionuclides of technical origin in the marine environment. The major attention is paid to the investigation of the radionuclide 137Cs distribution, since the investigations show the high values of the volumetric activity of this radionuclide to be present in the sea water thus far. Besides that, 137Cs radionuclide can be used as a tracer in investigations of the migration of other passive admixtures in the Baltic Sea water. Quite a number of scientists research the problems related with the amounts of the radionuclide of technical origin, their spread and impact on the marine environment. However, the works considering a problem of the variations of volumetric activity of radionuclides and their transfer in the coastal waters of the Baltic Sea practically are not encountered. Considering that, the volumetric activity of radionuclide 137Cs in the coastal surface waters of the Lithuanian territorial zone of the Baltic Sea... [to full text]

The evaluation of the passive admixture transfer in the marine environment is very significant from the point of view of environmental protection. A particular attention is devoted to the Baltic Sea ecological state, which is strongly influenced by the peculiarities of the sea bottom, weak connection with the World Ocean, climatic and hydrometeorological conditions. During the recent decades, the tendency of increment of the amount of anthropogenic pollutants is observed. The development of nuclear energetics and technology inevitably causes the spread of radionuclides of technical origin in the marine environment. The major attention is paid to the investigation of the radionuclide 137Cs distribution, since the investigations show the high values of the volumetric activity of this radionuclide to be present in the sea water thus far. Besides that, 137Cs radionuclide can be used as a tracer in investigations of the migration of other passive admixtures in the Baltic Sea water. Quite a number of scientists research the problems related with the amounts of the radionuclide of technical origin, their spread and impact on the marine environment. However, the works considering a problem of the variations of volumetric activity of radionuclides and their transfer in the coastal waters of the Baltic Sea practically are not encountered. Considering that, the volumetric activity of radionuclide 137Cs in the coastal surface waters of the Lithuanian territorial zone of the Baltic Sea... [to full text] / Pasyviųjų priemaišų jūrinėje aplinkoje įvertinimas ypač svarbus gamtosauginiu aspektu. Ypatingas dėmesys skiriamas Baltijos jūros ekologinei būklei, kurią lemia jūros dubens ypatybės, silpnas ryšys su Pasauliniu vandenynu, klimatinės ir hidrometeorologinės sąlygos. Pastaraisiais dešimtmečiais jūros baseine didėja antropogeninės kilmės teršalų kiekis. Branduolinės fizikos ir technikos plėtra neišvengiamai sukelia technogeninės kilmės radionuklidų patekimą į jūrinę aplinką. Daug dėmesio skiriama 137Cs radionuklidui, nes iki šiol jūros vandens tyrimai rodo aukštas šio radionuklido tūrinio aktyvumo reikšmes. Be to, 137Cs radionuklidas geras indikatorius, tiriant kitų pasyviųjų priemaišų migraciją Baltijos jūros vandenyje. Daug mokslininkų nagrinėja problemas, susijusias su technogeninės kilmės radionuklidų kiekiais, jų sklaida ir poveikiu jūrinei aplinkai. Tačiau darbų, kuriuose būtų nagrinėjama radionuklidų tūrinių aktyvumų pokyčių bei pernašos Baltijos jūros priekrantės vandenyje problema, praktiškai nėra. Atsižvelgiant į tai, šiame darbe nustatytas 137Cs radionuklido tūrinis aktyvumas Baltijos jūros Lietuvos priekrantės paviršiniame vandenyje bei įvertinti hidrometeorologiniai parametrai. 137Cs radionuklido tūrinis aktyvumas Baltijos jūros vandenyje nėra pastovus, todėl aktualu parinkti tinkamus nustatymo metodus ir vertinti jo pokyčių tendencijas. Įvertinus radiocezio tūrinio aktyvumo pokyčius priekrantės vandenyje, galima modeliuoti ir prognozuoti taršos šaltinio atsiradimo... [toliau žr. visą tekstą]