Presence Of Artificial Radionuclides Research Articles

Анализ результатов радиоэкологического мониторинга в регионе размещения Ленинградской АЭС

The paper presents results of long-term monitoring of radioecological situation in the area sur-rounding the Leningrad NPP (LNPP), that covers the periods before the Chernobyl accident (1980-1985), during and immediately after the accident (1986-1992) and the late period (2013-2014). After the Chernobyl accident the enhanced radioactivity level in the environment including soil and vegetation was registered in the area surrounded the Leningrad NPP. Several test points for sampling were selected inside the 30-km zone around the LNPP. Before the accident, in 1985, 137Cs soil contamination density was 3 kBq/m2; immediately after the accident, in 1986, the contamination density increased by 10 fold. In the late period, in 2013, the 137Cs soil contamina-tion density reduced significantly, however it exceeded the levels registered in 1985 by 2.6-7.3 times. 90Sr soil contamination density was 1.4-1.6 kBq/m2 both before and after the accident (1985-1992). The presence of artificial radionuclides in agricultural produce before 1985 was caused by global radioactive fall-outs, however no radionuclides emissions from the Leningrad NPP were registered. Average 137Cs content in grain and intertilled crops exceeded their content before 1986 by 19-44 times; the high content was associated with the contamination of the vege-tation by airway. The 137Cs content in agricultural produce is still higher than the level registered before the Chernobyl accident by 1.4-2.1 times, but the current levels are many times less than the current acceptable level. The levels exceeding the acceptable magnitude are found in wild berries only, that grow in some swampland with 137Cs soil contamination density of 3-9 kBq/m2 near the LNPP. Dynamics of transfer factors of 90Sr and 137Cs from soil to agricultural produce in the LNPP area was evaluated. The soil properties and the Chernobyl fall-out are shown to affect the factor magnitude. Presented data demonstrate that the Leningrad NPP operating in the standard way does not influence strongly on radiological situation in the 30-km zone around the NPP.

Presence of artificial radionuclides in samples from potable water and wastewater treatment plants

Human activity, such as the operation of nuclear power plants (NPPs) and the use of radionuclides in nuclear medicine, results in the presence of artificial radionuclides in surface waters, which may even reach potable water treatment plants (PWTPs) and wastewater treatment plants (WWTPs).In this study, water and sludge samples from a PWTP are radiologically monitored. The incoming water of the plant is influenced by the presence of an NPP upstream. Two WWTPs receiving wastewater from medical centres and other origins are also studied. As a result, 131I, 60Co and 137Cs have been determined in the dewatered sludge samples from the PWTP, while 131I, 99mTc, 67Ga and 111In were detected in the sludge samples from the WWTPs. The radionuclide activities in the influent water from the WWTPs studied were lower than the minimum detectable activity values. Therefore, on the basis of our results, the analysis of sludge samples is very useful as it enables the concentration of any radionuclides that may be present in the incoming water.Lastly, as higher activity of 131I was detected in the samples studied, the total effective dose was assessed for WWTP workers, as they handle dewatered sludge containing this radionuclide. It can be concluded that there is no risk in terms of total exposure.

Investigation of Natural Gamma Radioactivity Levels and Associated Dose Rates from Surface Soils in Ore Metropolis, Ondo State, Nigeria

Natural radioactive materials under certain conditions can reach hazardous radiological levels. Therefore, it becomes necessary to study the natural radioactivity levels in soil to assess the dose to the population in order to determine the health risks and to obtain a baseline for future changes that may occur due to human activities. The motivation for this study was the devastating civil war that took place in Nigeria from 1967 to 1970, in which the study area was one of the battle fields. The results of our investigations of the soil in the metropolis of Ore show that the activity concentrations of 226Ra, 232Th and 40K in the soil vary from 14.21±1.40 to 25.87±1.01Bq/kg; 5.30±1.00 to 20.99±1.10Bq/kg and 58.01±1.80 to 382.98±3.00Bq/kg respectively. The total absorbed dose rate calculated from the activity concentrations of 226Ra, 232Th and 40K ranged from 15.42±1.10 to 40.99±1.36 nGy/h. The radium equivalent activity (Req) and the annual effective dose rates were also calculated and found to vary from 33.39±2.44 to 85.07±2.96 Bq/kg and from 18.91±1.35 to 50.27±1.69 µSv/y respectively. These values were found to be within the same range as recommended values (UNSCEAR, 2000). The study also indicated that 137Cs detected at three locations is an indication of the presence of artificial radionuclides which can be linked to the war that took place in the ancient town of Ore.

Anthropogenic radionuclides bioaccumulation in Antarctic marine fauna and its ecological relevance

The paucity of investigations on the presence of artificial radionuclides and their bioaccumulation in Antarctic fauna is due to the erroneous belief that this area is pristine. We report evidence that significant levels of the artificial radionuclides Sr-90, Cs-137, Am-241 and plutonium isotopes can be found in sponges, bivalves, krill and demersal fish fauna of Terra Nova Bay (Ross Sea), sometimes with a seasonal pattern. Increasing concentrations of Cs-137 were detected in the bivalve Adamussium colbecki (Antarctic scallop) during austral summer months, as a result of major trophic activity and changes in metabolic rates. Bioconcentration factors for artificial radionuclides in different Antarctic species are presented and discussed in relation to their different trophic strategies. Unexpectedly high radiocesium bioconcentration factors determined in bivalves suggested the particular role played by filter feeding in bioaccumulation, particularly in summer when radionuclide bioavailability is enhanced. The feeding preference of the trematomiid fish Trematomus bernacchii for the scallop A. colbecki is confirmed, not only by fish gut content analyses, but also through radiometric results. Transuranics bioaccumulation by sensitive species allowed some interesting comparisons on the different plutonium contamination of the southern hemisphere with respect to the northern one.