Distribution of 239,240Pu in marine products from the seas around the Korean Peninsula after the Fukushima nuclear power plant accident

Comparative Study of Plutonium and Radiocaesium Content in the Muscle of Fish of the Yenisey River

This work reports the first data on the content of plutonium (^239+240Pu) in the muscle tissues of the Northern pike (Esox lucius) and the Siberian dace (Leiciscus baicalensis) inhabiting the middle reaches of the Yenisey River in the vicinity of the radioactive discharge site. An increase in the content of ^239+240Pu and radiocaesium (¹³⁷Cs) in pike muscles followed an increase in the volume of controlled discharges of these radionuclides to the Yenisey in 2018. The content of ^239+240Pu in the muscles of pike (2-11 mBq/kg dry weight) and dace (1-4 mBq/kg dry weight) of the Yenisey fall within the range of values obtained by other authors for the ichthyofauna from water bodies contaminated with radioactive discharges from nuclear power plants and spent nuclear fuel processing plants. The ratio of the activity concentrations ^239+240Pu/¹³⁷Cs in fish muscles, compared with the similar ratios in other hydrobionts, indicates a significantly lower bioavailability of plutonium for fish. The obtained preliminary results make it possible to consider the Northern pike as a more prospective indicator of biologically available plutonium in the Yenisey than the dace.

Radioactive impacts of the Fukushima Dai-ichi Nuclear Power Plant Accident on blue sharks in the Northwest Pacific

The Fukushima Dai-ichi Nuclear Power Plant Accident (FDNPPA) derived ¹³⁴Cs, ¹³⁷Cs and ^110mAg in blue sharks captured in the Northwest Pacific during 2011-2018 were assessed for the first time in the aspects of radioactive contamination, temporal variation, maternal-to-fetus transfer, tissue distribution and radiation dose, to demonstrate the impacts of the FDNPPA on blue sharks. The contribution of the FDNPPA derived radiocesium in blue sharks (>52%) was estimated based on ¹³⁴Cs/¹³⁷Cs_{activity ratios}. The effective and ecological half-lives of the FDNPPA derived ¹³⁴Cs (270 d, 410 d), and ¹³⁷Cs (430 d, 450 d) were calculated. These contaminations decreased with time and returned to the level before the FDNPPA during the period of Sep. 2017-Sep. 2018.¹³⁴Cs and ¹³⁷Cs tended to distribute in muscles, while ^110mAg mainly distribute in their guts. ¹³⁴Cs and ¹³⁷Cs were also transferred to fetuses and the activities were up to ~30% of the maternal activities. Dose assessment demonstrated that the highest FDNPPA derived dose rate in blue sharks (~0.42 nGy/h) was far below the ERICA ecosystem screening benchmark of 10 μGy/h and the committed effective dose in humans from ingesting blue shark meat (0.06-0.90 μSv) was far less than that from annual consumption of food and water. It was far from causing radiation harm to blue sharks and humans, suggesting that the impacts of the FDNPPA on blue sharks were not significant.

Novel DGT Configurations for the Assessment of Bioavailable Plutonium, Americium, and Uranium in Marine and Freshwater Environments

Plutonium, americium, and uranium contribute to the radioactive contamination of the environment and are risk factors for elevated radiation exposure via ingestion through food or water. Due to the significant environmental inventory of these radioelements, a sampling method to accurately monitor their bioavailable concentrations in natural waters is necessary, especially since physicochemical factors can cause significant temporal fluctuations in their waterborne concentrations. To this end, we engineered novel diffusive gradients in thin-film (DGT) configurations using resin gels, which are selective for UO₂²⁺, Pu(IV + V), and Am(III) among an excess of extraneous cations. In this work, we also report an improved synthesis of our in-house ion-imprinted polymer resin, which we used to manufacture a resin gel to capture Am(III). The effective diffusion coefficients of Pu, Am, and U in agarose cross-linked polyacrylamide were determined in freshwater and seawater simulants and in natural seawater, to calibrate these configurations for environmental deployments.

The assessment of the annual effective dose due to ingestion of radionuclides from drinking water consumption: calculation methods

In the present paper the different ways of assessing the annual effective dose due to ingestion of radionuclides by drinking water consumption were examined and exemplified. On a set of 10 samples the gross alpha activity, the gross beta activity, the concentration of 210Po, 210Pb, 238U, 232Th and, 226Ra were measured. The highest annual effective dose values assessed by relying on the investigated sample set were found by using the rationale according to which all the gross alpha and beta activity is due to the alpha and beta radionuclide, with the highest effective dose coefficient, namely 210Po and 210Pb/228Ra, respectively.