Aquatic live animal radiotracing studies for ecotoxicological applications : addressing fundamental methodological deficiencies

The use of live animal gamma radioisotope tracer techniques in the field of ecotoxicology allows laboratory studies to accurately monitor contaminant biokinetics in real time for an individual organism. However, methods used in published studies for aquatic organisms are rarely described in sufficient detail to allow for study replication or an assessment of the errors associated with live animal radioanalysis to be identified. We evaluate the influence of some important methodological deficiencies through an overview of the literature on live aquatic animal radiotracer techniques and through the results obtained from our radiotracer studies on four aquatic invertebrate species. The main factors discussed are animal rinsing, radioanalysis and geometry corrections. We provide examples of three main techniques in live aquatic animal radiotracer studies to improve data quality control and demonstrate why each technique is crucial in interpreting the data from such studies. The animal rinsing technique is also relevant to non-radioisotope tracer studies, especially those involving nanoparticles. We present clear guidance on how to perform each technique and explain the importance of proper reporting of the validation of each technique for individual studies. In this paper we describe methods that are often used in lab-based radioecology studies but are rarely described in great detail. We hope that this paper will act as the basis for standard operating procedures for future radioecology studies to improve study replication and data quality control

The transfer of 137Cs, Pu isotopes and 90Sr to bird, bat and ground-dwelling small mammal species within the Chernobyl exclusion zone

Protected species are the focus of many radiological environmental assessments. However, the lack of radioecological data for many protected species presents a significant international challenge. Furthermore, there are legislative restrictions on destructive sampling of protected species to obtain such data. Where data are not available, extrapolations are often made from ‘similar’ species but there has been little attempt to validate this approach. In this paper we present what, to our knowledge, is the first study purposefully designed to test the hypothesis that radioecological data for unprotected species can be used to estimate conservative radioecolgical parameters for protected species; conservatism being necessary to ensure that there is no significant impact. The study was conducted in the Chernobyl Exclusion Zone. Consequently, we are able to present data for Pu isotopes in terrestrial wildlife. There has been limited research on Pu transfer to terrestrial wildlife which contrasts with the need to assess radiation exposure of wildlife to Pu isotopes around many nuclear facilities internationally. Our results provide overall support for the hypothesis that data for unprotected species can be used to adequately assess the impacts for ionising radiation on protected species. This is demonstrated for a range of mammalian and avian species. However, we identify one case, the shrew, for which data from other ground-dwelling small mammals would not lead to an appropriately conservative assessment of radiation impact. This indicates the need to further test our hypothesis across a range of species and ecosystems, and/or ensure adequate conservatism within assessments. The data presented are of value to those trying to more accurately estimate the radiation dose to wildlife in the Chernobyl Exclusion Zone, helping to reduce the considerable uncertainty in studies reporting dose-effect relationships for wildlife. A video abstract for this paper is available here

Estimating the exposure of small mammals at three sites within the Chernobyl exclusion zone – a test application of the ERICA Tool

An essential step in the development of any modelling tool is the validation of its predictions. This paper describes a study conducted within the Chernobyl exclusion zone to acquire data to conduct an independent test of the predictions of the ERICA Tool which is designed for use in assessments of radiological risk to the environment. Small mammals were repeatedly trapped at three woodland sites between early July and mid-August 2005. Thermoluminescent dosimeters mounted on collars were fitted to Apodemus flavicollis, Clethrionomys glareolus and Microtus spp. to provide measurements of external dose rate. A total of 85 TLDs were recovered. All animals from which TLDs were recovered were live-monitored to determine 90Sr and 137Cs whole-body activity concentrations. A limited number of animals were also analysed to determine 239,240Pu activity concentrations. Measurements of whole-body activity concentrations and dose rates recorded by the TLDs were compared to predictions of the ERICA-Tool. The predicted 90Sr and 137Cs mean activity concentrations were within an order of magnitude of the observed data means. Whilst there was some variation between sites in the agreement between measurements and predictions this was consistent with what would be expected from the differences in soil types at the sites. Given the uncertainties of conducting a study such as this, the agreement observed between the TLD results and the predicted external dose rates gives confidence to the predictions of the ERICA Tool

How it helps fight the pandemic of COVID-19

This thesis contains a brief description of how IT helps in fighting the pandemic of COVID-19 in many areas of our life (working processes, education, medicine, and politics)

Non radiochemical technique for

Nondestructive methods of 90Sr determination were developed for small biological objects, such as small rodents, to keep biological object going for further research even in presence of essential contamination of the same object by 137Cs. To carry out 137Cs input registration in proper way, we used 2 different methods: a) The method of Cs and Sr electrons filtering using thin filters with subsequent measurement of residual Y-spectrum. Comparative results of measurements for calibrated and studied samples were found not hard to obtain the amount of 90Sr. Obtained result is close to the real one if the ratio between Cs and Sr is comparable. In opposite case the method requires several measurements depending on 137Cs/90Sr relation b) Method of beta-gamma spectrometry with specially elaborated beta-gamma spectrometer and corresponding software. General distinction of this spectrometer from the standard one is using the special procedure of experimental spectrum operation, and the use of thin (~1mm and 0,1mm) scintillator as a detector that allows to have the effectiveness of registration of gamma quanta of 661 keV in one-two orders less than for electrons with the same energy. The experimental spectrum operation was realised by the method of inserting into one of the calibrated spectrums, which had been measured on the same spectrometer from specially fabricated phantoms of mice with known contents of 137Cs and 90Sr+90Y. Method provides contemporary content of 90Sr and 137Cs. Procedure of standard radiochemical determination for 90Sr contents conducted in 13 mice on the final stage of studies has confirmed the method reliability