Activity Concentrations Of Anthropogenic Radionuclides Research Articles

Initiation of radioecological monitoring of forest soils and plants at the Lithuanian border region before the start of the Belarusian nuclear power plant operation.

Knowledge of the background activity concentrations of anthropogenic radionuclides before the start of operation of the new nuclear power plant in Belarus, BelNPP, is an issue of great importance for neighbouring countries. In this study, we provide the pilot characterisation of the Lithuanian part of the 30-km zone of the BelNPP, emphasising the forest plants, terrestrial mosses, forest organic and mineral topsoil to describe the preoperational radioecological state of the pine forest ecosystem. Key anthropogenic radionuclides (14C, 3H, 137Cs and 239,240Pu) were analysed. The 14C specific activity varied from 97.80 ± 1.30 to 102.40 ± 0.79 pMC. The 3H specific activity in the tissue-free water tritium form varied from 13.2 ± 2.2 TU to 20.8 ± 2.3 TU, which corresponded to the 3H level of precipitation in this region. The activity concentrations of 239,240Pu in soil and moss samples did not exceed 1 Bq/kg and were mainly due to global fallout after nuclear tests. The 137Cs inventory in the pine forest soils of the Lithuanian part of the BelNPP 30-km zone varied from 930 ± 70 to 1650 ± 430 Bq/m2. High variation of the inventory and uneven distribution in the soil profile conditioned a wide range of 137Сs activity in terrestrial plants from 1.0 ± 0.5 to 40.5 ± 1.8 Bq/kg dry weight. The abundance of microorganisms in different seasons and soil depths do not exceed the natural levels. According to PCA loads, the number of microorganisms and variability of 137Cs specific activity is determined by soil abiotic parameters.

137Cs and plutonium isotopes accumulation/retention in bottom sediments and soil in Lithuania: A case study of the activity concentration of anthropogenic radionuclides and their provenance before the start of operation of the Belarusian Nuclear Power Plant (NPP)

Knowledge of the background activity concentrations of anthropogenic radionuclides before the start of operations of the new nuclear facilities in Belarus is of great value worldwide. Inland water bodies in Lithuania (specifically the Neris River, the Nemunas River and the Curonian Lagoon) are near the site of the Belarusian NPP under construction and, for this reason, sediments and flooded soils from these sensitive areas were analysed for radiocesium and plutonium isotopes (macrophytes were analysed only for 137Cs) in 2011–2012. The 137Cs and 239+240Pu activity concentrations in bottom sediments from the Nemunas River, sampled in 1995–1996 and re-calculated to the year 2016, were compared with those of 2011–2012. The obtained activity of 137Cs in bottom sediments of the Nemunas River and Curonian Lagoon varied from 1 Bq/kg to 47.0 Bq/kg. The activity of 137Cs in the tested soils ranged from 5.3 B g/kg to 32.9 Bq/kg. The 239+240Pu activity in bottom sediments of the studied sampling sites varied between 0.016 and 0.34 Bq/kg and in flooded soils from 0.064 to 0.55 Bq/kg. The 238Pu activity values were very low or lower than the detection limit. The activity of 137Cs in macrophytes varied from values lower than the detection limit to 6 Bq/kg. A strong positive linear correlation for bottom sediments was calculated between: 239+240Pu and total organic carbon (TOC), r = 0.86, p-value 0.01; 239+240Pu and silt, r = 0.80, p-value 0.029; 137Cs and silt, r = 0.78, p-value 0.04; and 137Cs and TOC, r = 0.85, p-value 0.015. The similar peculiarities of 137Cs and 239+240Pu accumulation in bottom sediments and flooded soil allow us to assume that 137Cs can be used as a tracer for 239+240Pu in the initial stage of searching for radionuclide accumulation zones. A remaining impact of the Chernobyl fallout in average comprised: in the Lower Nemunas River and Curonian Lagoon sediments – 51%, in the Middle Nemunas River −90% and in the floodplains of the Nemunas River – 59%, while the provenance of plutonium in studied bottom sediments and flooded soil was the global fallout.

Activity concentration of anthropogenic radionuclides in soil samples

Activity concentration of anthropogenic radionuclides in soil samples

Activity concentration of terrestrial and anthropogenic radionuclides (226Ra, 222Rn, 232Th, 40K, and 137Cs) in soil samples

Measurement of the activity concentrations of terrestrial and anthropogenic radionuclides in one hundred fifteen soil samples collected from various locations in Samsun city was taken using a gamma-ray spectrometer with a NaI (Tl) detector. The average activity concentrations of terrestrial radionuclides 226Ra, 232Th, and 40K were measured as 38.1 ± 1.4, 39.3 ± 0.8, and 375.3 ± 10.2 Bq kg−1, respectively. The average activity concentration of anthropogenic radionuclide 137Cs measured in some soil samples was found as 12.1 ± 0.7 Bq kg−1. Radon concentrations in soil and in air were estimated using results of the measurement of activity concentrations of 226Ra. The average concentrations of radon in soil and air were found as 32 kBq m−3 and 101 Bq m−3, respectively. The absorbed gamma dose rate in outdoor air due to terrestrial radionuclides in soil samples varied from 28 to 95 nGy h−1 with an average of 57 nGy h−1. The annual effective dose rates caused from external and inhalation exposure were estimated as 70 and 958 μSv y−1, respectively.

Natural and anthropogenic radionuclide activity concentrations in the New Zealand diet

To support New Zealand's food safety monitoring regime, a survey was undertaken to establish radionuclide activity concentrations across the New Zealand diet. This survey was undertaken to better understand the radioactivity content of the modern diet and also to assess the suitability of the current use of milk as a sentinel for dietary radionuclide trends. Thirteen radionuclides were analysed in 40 common food commodities, including animal products, fruits, vegetables, cereal grains and seafood. Activity was detected for 137Caesium, 90Strontium and 131Iodine. No other anthropogenic radionuclides were detected. Activity concentrations of the three natural radionuclides of Uranium and the daughter radionuclide 210Polonium were detected in the majority of food sampled, with a large variation in magnitude. The maximum activity concentrations were detected in shellfish for all these radionuclides. Based on the established activity concentrations and ranges, the New Zealand diet contains activity concentrations of anthropogenic radionuclides far below the Codex Alimentarius guideline levels. Activity concentrations obtained for milk support its continued use as a sentinel for monitoring fallout radionuclides in terrestrial agriculture. The significant levels of natural and anthropogenic radionuclide activity concentrations detected in finfish and molluscs support undertaking further research to identify a suitable sentinel for New Zealand seafood monitoring.

Radioactivity of plutonium isotopes, 137Cs and their ratio in sediment, seawater and biota from the east coast of Peninsular Malaysia

This study with sampling expeditions of marine sediment, seawater and biota were performed at 30 stations within Malaysian Exclusive Economic Zone (EEZ). A total of >400 samples were collected to determine the activity concentration of anthropogenic radionuclides (239+240Pu, 137Cs) and their activity ratio (239+240Pu/137Cs) in sediments, seawater and biota. The purpose of this study was to determine the concentration levels for these radionuclides and to evaluate any occurrence of radioactive contamination. Sediment cores were obtained using multicorer device, while water samples via co-precipitation techniques and biota was purchased from local fishermen. The activity concentrations of 239+240Pu in sediment, seawater and biota were ranged 0.21–0.45 Bq/kg dry wt., 2.33–7.95 mBq/m3 and <0.008 Bq/kg fresh wt., respectively. Meanwhile, the values of 137Cs were ranged <1.00–2.71 Bq/kg dry wt. in sediment, 3.40–5.89 Bq/m3 in seawater and <0.05–0.41 Bq/kg fresh wt. in biota, respectively. Activity ratios of 239+240Pu to 137Cs obtained seem to confirm that these artificial radioactivities were mainly due to global nuclear fallout.

Accumulation of anthropogenic radionuclides in cryoconites on Alpine glaciers

Cryoconites are airborne sediments which accumulate on the surface of glaciers. In samples of cryoconites a temperate Austrian glacier high activity concentrations of anthropogenic radionuclides were found, which stem from global and Chernobyl fallouts. Radionuclides identified were 137Cs, 134Cs, 238Pu, 239+240Pu, 90Sr, 241Am, 60Co, 154Eu, 207Bi, and 125Sb. Given the approximately known isotopic ratios, Cs and Pu can be separated into the contributions of either source of origin. Published 137Cs/ 134Cs and 239+240Pu/ 238Pu ratios were used for the discrimination of the Dachstein-glacier cryoconites according to their origin from global or Chernobyl fallout. Two different groups of cryoconites were identified, an older population dominated by nuclear weapons fallout and a younger one with predominant Chernobyl fallout. With those data a simple model was formulated to demonstrate the transition and mixing of these two populations on the glacier surface.