Radionuclide contamination in flood sediment deposits in the coastal rivers draining the main radioactive pollution plume of Fukushima Prefecture, Japan (2011–2020)

Artificial radionuclides including radiocesium (134Cs and 137Cs) and radiosilver (110mAg) were released into the environment following the Fukushima Dai-ichi nuclear power plant accident in March 2011. These particle-bound substances deposited on soils of north-eastern Japan, located predominantly within a ∼3000 km2 radioactive fallout plume and drained by several coastal rivers to the Pacific Ocean. The current dataset (Evrard et al., 2021), which can be accessed at https://doi.org/10.1594/PANGAEA.928594, compiles gamma-emitting artificial radionuclide activities measured in 782 sediment samples collected from 27 to 71 locations across catchments draining ∼6450 km2 during 16 fieldwork campaigns. These campaigns were conducted in Japan between November 2011 and November 2020 in river catchments draining the main radioactive plume. This database may be useful to evaluate and anticipate the post-accidental redistribution of radionuclides in the environment and for the spatial validation of models simulating the transfer of radiocesium across continental landscapes.

Radionuclide contamination in flood sediment deposits in the coastal rivers draining the main radioactive pollution plume of Fukushima Prefecture, Japan (2011–2020)

Artificial radionuclides including radiocesium (134Cs and 137Cs) and radiosilver (110mAg) were released into the environment following the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011. These particle-bound substances deposited on soils of Northeastern Japan located predominantly within a ~3000 km2 radioactive fallout plume and drained by several coastal rivers to the Pacific Ocean. The current dataset that can be accessed at https://doi.pangaea.de/10.1594/PANGAEA.928594 compiles gamma-emitting artificial radionuclide activities measured in 782 sediment samples collected from 27 to 71 locations during 16 fieldwork campaigns conducted in Japan between November 2011 and November 2020 in river catchments draining the main radioactive plume. This database may be useful to evaluate and anticipate the post-accidental redistribution of radionuclides in the environment and for the spatial validation of models simulating the transfer of radiocesium across continental landscapes.

Where the Meghalayan meets the Anthropocene: Stratigraphic signals of human-environmental interactions on the periphery of Indian civilisation

The aims of this study were to review human-environment interactions during the Meghalayan and to search for the stratigraphic boundary of a new epoch, informally termed the Anthropocene, as well as to determine whether the stratigraphic signals of human activity on the Meghalaya Plateau in Northeast India can be correlated globally. This plateau is the base of the Meghalayan Age that was determined from a speleothem in a cave located on it. Review indicates that study region developed on the periphery of ancient Indian civilisation, with stratigraphic signals of human activity being apparent in only the last few thousand years; that is, substantially later than the neighbouring ancient Indian civilisation. The stratigraphic signals are heterogeneous and diachronous, not only as a result of various human activities, but also in the effect of the diverse sensitivities of the environment to anthropogenic disturbances. A discrete and visible cultural layer that relates to the development of settlements and the production of new materials is still being formed and reworked. The only synchronous stratigraphic signal with a global range seems to be associated with the artificial radionuclide fallout from nuclear weapons testing, which covers a topsoil layer of up to tens of centimetres thick

Levels of dose-forming radionuclides in the young perch (Perca fluviatilis) in the Zaporizke Reservoir

It had been investigated the content levels and the coefficients of accumulation from water of the main dose-forming radionuclides (137Cs, 90Sr, 226Ra, 232Th, 40К) in different-age Perca fluviatilis from the Samara Bay and the lower part of the Zaporizke Reservoir. The three age groups of fish were used: one-summer old (0+), two summers old (1+), and three summers old (2+). The obtained data on consecutive reduction of radionuclide activity values in juvenile perch showed that maximal 137Cs content was found in individuals of age (0+), and the minimal one – in individuals aged (1+) from Samara Bay. The maximal accumulation of radioisotopes 90Sr was in individuals aged (0+) in the lower part of the Zaporizke Reservoir, and the minimal one in the perch of age (1+) in the Samara Bay. The highest levels of 226Ra and 40K were found in the (0+) fish from the Samara Bay, and the lowest contents were in individuals aged (2+) in the lower part of the reservoir. The value of the 232Th content level was maximal in the two-summer-olds from the lower part of the reservoir, and the minimal one – in (0+) fish from the Samara Bay. Artificial radionuclide 137Cs was accumulated in the largest amount by perch (0+) from the Samara Bay, and 90Sr – by fish from the lower part of the Zaporizke Reservoir. By values of accumulation coefficients, 232Th was in second place after 137Cs, indicating its significant contribution to the formation of the total dose of radiation. Majority of radioisotopes investigated were more intensively accumulated by the juvenile perch in the Samara Bay compared to the lower part of the Zaporizke Reservoir. The highest level of radionuclide accumulation at both studied sites of the Zaporizke Reservoir has been observed in (0+) fish.

Effect of Fukushima Accident on Fishes and Fish Like other Foods Collected from the Bay of Bengal and Karnaphuli River, Bangladesh

An experiment was carried out to assess the radiological exposure due to the intake of fishes and fish like foods from some common estuary (Karnaphuli River) and Marine (Bay of Bengal) contaminated by Fukushima Reactor Accident, if any, by using gamma spectroscopy. The analysis was done to estimate the radioactivity concentrations due to natural radionuclides namely 238U, 232Th and 40K and artificial radionuclide 137Cs in Karnaphuli estuary and Chittagong city adjoining Bay of Bengal fish and fish-like samples. The activity concentration for 238U in all the samples ranged from 0.10615 ± 0.0000 to 2.4767 ± 0.0005 Bq.kg-1 with the mean of 0.6109 ± 0.0001 Bq.kg-1. The Activity of 232Th ranged from 0.0009 ± 0.0000 to 0.0273 ± 0.0000 Bq.kg-1 with the mean of 0.0074 ± 0.0000 Bq.kg-1. The activity concentration for 40K was found to be in the range from 1.5516 ± 0.0311 to 74.8658 ± 0.2532 Bq.kg-1 with the mean of 24.9533 ± 0.0702 Bq.kg-1. The artificial radionuclide 137Cs was not found in any of the samples. The specific activity values for most of the sample were within the permissible limits. The average effective dose and internal hazard index due to consumption of those fishes and fish-like foods was found to be 0.1 mSv.y-1 and 0.0085 ± 0.0000 mSv.y-1 respectively. The research work showed that the consumers of concerned fishes and fish-like foods of the Chittagong area have no risk of radioactivity ingestion even though no amount of radiation is assumed to be totally safe. The Chittagong Univ. J. Sci. 40(1) : 75-96, 2018

Present Status of Marine Radioecology in Bali and Lombok Waters: Distribution Study of 137Cs and Natural Radionuclides in Lombok Strait

Lombok strait is outflow of water masses from the Pacific Ocean to the Indian Ocean by Indonesian Throughflow (ITF). Radioecology studies in these waters were including monitoring of natural and artificial radionuclide. This study aims to obtain baseline data of artificial radionuclide 137Cs that entering from the Pacific Ocean through the Makassar Strait. The sampling location were covered territorial waters of Bali and Lombok. A large volume sample preparation for the 137Cs analysis were performed by co-precipitation process using K4Fe(CN)6 and CuCl2 at pH 8-9. Measurement of the concentration activity of natural radionuclides and 137Cs were using Gamma HPGe spectrometer with 20 – 25 % efficiency. The result of this study indicate the average concentration of 40K 226Ra 212Pb 214Bi 228Ac 214Pb and 137Cs in the sediments of Strait Bali waters respectively 165.16 Bq kg-1, 25.11 Bq kg-1, 8.36 Bq kg-1, 7.51 Bq kg-1, 7.05 Bq kg-1, 6.68 Bq kg-1 and the lowest of 0.15 Bq kg-1. In the waters of Lombok concentration activity of radionuclides 40K 226Ra 212Pb 214Bi 228Ac 214Pb and 137Cs in the sediments was 172.00 Bq kg-1, 25.88 Bq kg-1, 10.10 Bq kg-1, 6.50 Bq kg-1, 6.39 Bq kg-1, 5.70 Bq kg-1 and 0,162 Bq kg-1. The concentration activity of 137Cs in seawater of Bali and Lombok respectively was 0.113 Bq m-3 and 0.644 Bq m-3. Keyword : Natural Radionuclide, 137Cs, Lombok Strait