FANTANELE str. nr. 30
postal code : 400294
Fax : +40264 30 70 32
Lect. dr. Begy Robert-Csaba
Radionuclides As tracers of the Anthropic influence on the Danube Delta sedimentary processes
Gamma and alpha spectrometry laboratory
Radioactive measuring techniques in environmental problems have a large application field, such as sediment dating, lake silting studies, soil erosion, applications in meteorology and climatology, tracers.
Studies regarding natural and artificial radioactivity by gamma spectrometry
Throughout our existence we are exposed to multiple hazards, the radioactive contamination risk having a profound echo in the general public. Among the identification methods and the quantification of radioactive pollutants, the gamma spectrometry is remarked as being a method characterized with a large activity, in both radioactive products, which it can be used for, and sample types (soil, sediment, water, air, organic matter etc.) with a very good precision, a fast determination time and a simple preparation of the samples. Beside the issue of a radioactive contamination, the study of natural radioactivity is important in both soils and construction materials because their effect can lead to increasing the radiation background and growth of the natural dose. The effects of the low doses is not well known yet. The utilisation of radionuclides as tracers in various erosion and sedimentation processes are of great importance as well, these radionuclides being easily and precisely determined by gamma spectrometry.
Studies regarding natural and artificial radioactivity using alpha spectrometry
The last few years show a dramatic increase of scientific studies regarding applications of alpha spectrometry. This analytic method allows the determination and quantification of radionuclides in environmental samples at a very low concentration level. The alpha spectrometry shows some advantages in comparison with other measuring techniques low activity radioactive isotopes, some of these being the very good precision, low background of the detector, elimination of interfering radiations by chemical separation, the ability of using eliminatory isotopes of alpha particle as tracers, the wide domain of the method applicability. Theoretically, any sample, which can be dissolved and which emits alpha particles, can be analysed by this method.
Radioactive dating using Pb-210 and Cs-137
Information stored in natural sedimentary archives is used in a large range for environmental samples, such as:
· Modifications in pedological erosion processes, processes which can be consequences of deforestation, forest recultivation or changes in agricultural procedures.
· Historical highlighting of water quality changes in laces associated with problems such as eutrophication or acid rains.
· Monitoring of atmospheric pollution with heavy metals, organic polluants and radioactive emissions from nuclear installations or other contamination sources.
The knowledge of an exact chronology of sediment depositions is of great importance in the interpreation of the information from these archives.
One of the most important sediment dating method for recent sediments is the one using Pb-210. This is a radioactive element present in soil and sediments, having a half-life of 22,3 years. The Rn-222 form the soil (originating from Ra-226), reaching the atmosphere followed by a series of successive short lived radionuclides, finally leading to the birth of Pb-210. Through precipitations and solid discharges this element is deposited on the surface of the soil, from where it is transported to the lakes. The Pb-210 produced in the atmosphere can vary in function of the season or the precipitation amount on a short time spam, the annual average is considered to be constant. Because of this property, Pb-210 can be used for the determination of the sedimentation rates in lakes for a period raging from 0-150 years.
Most recent studies are carried out on seven lakes from the Danube Delta, namely Cruhlig, Iacob, Matita, Merhei, Isac, Cuibida and Uzlina. Several studies have been made (and are in progress) regarding some physical parameters (water content, porosity, bulk density, LOI, attenuation coefficient), the Ra-226 and the Pb-210 content of the sediment cores, the ages of the sediment layers of each cores and the linear and mass sedimentation of each core.
Radium measurements from soils ant construction materials
Radium measurements from water samples via alpha spectrometry
Water and soil quality (NORM measurements)
Radioactive measurements for construction materials
Studies regarding artificial radionuclides in the environment caused by accidents (ex. Fukushima)
NORM and TENORM measurements in uraniferous areas
Natural radionuclides in soils and other geological materials
Monitoring of atmospheric pollution
Development and testing od protective foils for preventing alpha detector contaminations
Determination of uranium and thorium from environmental samples for dating purposes
Determination of erosion levels on cultivated and uncultivated soils
Determinations of sedimentation rates in natural an anthropic lakes