Anthropogenic Radionuclide Concentrations Research Articles

Baseline levels of radionuclides concentration in the sea of Wakatobi and Kendari

The importance of an information about the baseline value of radionuclides in the sea of Wakatobi and Kendari to see how large the input or contamination of radionuclides in the area. This contamination can come from waste human activities such as industry and nuclear utilization activities that are biased carried by seawater currents and air gusts. Natural and anthropogenic radionuclide concentrations in the Wakatobi and Kendari seas have been measured using a Gamma spectrometer (HPGe).The monitoring results show that both 226Ra, 232Th, 40K and 137Cs indicate that they are in normal condition and do not exceed the safe limit. The data presented in this study will be very important and useful to be used as basic data in mapping the improvement of radionuclide contamination in the area.

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.

Bioindication of 137Cs forest ecosystem pollution by using test objects

The results of the analysis of native and foreign publications containing data on the accumulation of radioactive substances by different plant species in forest ecosystems in different climatic zones are presented.It is noted that the problems of radioecological monitoring of forest ecosystems and bioindication of radiation pollution are analyzed by radioecologists during the global fallout of radionuclides from the late 1950s — early 1970s. It was found that high concentrations of anthropogenic radionuclides, which were the source of aerial entry into forest ecosystems after nuclear weapons testing, were observed in tree crowns. In the first period after the fall out of the air that high concentrations was observed mainly in the needles and leaves and later in the forest floor.Wood and non-timber components (secondary products) of forest ecosystems are used as a variety of resources. Among the latter, wild berries, medicinal plants and edible mushrooms have considerable diversity. Information on the current levels of radioactive contamination of forest ecosystem components can be obtained on the basis of two approaches: 1) analysis of the results of extensive radioecological monitoring of relevant forest products, with the selection and analysis of a significant number of samples; 2) bio indication method which is related to the analysis of radioactive contamination (137Cs specific activity) in the test objects of radio-ecological monitoring in forest ecosystems and conversion of relevant values for economically valuable products.It is justified that the use of certain types of vascular plants as test objects for radiation monitoring is acceptable. In general, sound selection of radioecological monitoring test objects and study of their characteristics regarding radioactive contamination of forest ecosystems allows predicting radioactive contamination of specific types of forestry products under conditions of radioactive contamination on a forest-typological basis. This method allows detecting quickly and in a timely manner the cases of increase of levels of radioactive contamination in forest ecosystems in comparison with the measurements made earlier (to record falls out on the ground of radionuclides).Such studies are also relevant in the areas of radioecological monitoring in the controlled areas of existing nuclear power plants, for example, Khmelnytsky NPP and Rivne NPP.The test objects used to bio-indicate radioactive contamination in forest ecosystems usually are higher plants (bryophytes and vascular plants), lichens and fungi.However, no specific research has been conducted on this issue in Ukraine, and currently distributed in the scientific literature the numerous data on 137Cs accumulation in the above-mentioned tests objects was obtained in different years, in different regions and forest conditions, in different species, which does not allow them to be used for up-to-date radioecological monitoring.

Complete dissolution of solid matrices using automated borate fusion in support of nuclear decommissioning and production of reference materials

Accurate measurement of natural and anthropogenic radionuclide concentrations is of critical importance to end users in the nuclear sector to ensure correct classification prior to storage, recycling, reprocessing or disposal. Uncertainties in the characterisation of solid matrices and materials could lead to safety, quality and financial implications. Robust sample preparation methods are vital, in particular effective sample digestion, as under-estimated chemical yield recovery results in a corresponding under-estimation of activity levels. Borate fusion has been proven to effectively digest a range of complex sample matrices in the geosciences but is not used routinely elsewhere. In this study, we describe an automated procedure for borate fusion of multiple matrices encountered in nuclear decommissioning, containing diverse radionuclides over a range of activity concentrations. The impact of digestion flux, sample mass and sample to flux ratios are described, as well as the subsequent separation and measurement techniques. The results contribute to accurate and precise measurement of radionuclides in various matrices, as well as to characterisation of reference materials, providing greater confidence in nuclear industry programmes worldwide.

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.

Reference levels of radioactive contamination of water bodies based on the environmental criteria

Quantitative environmental criteria for the radiation protection of aquatic ecosystems, namely, reference concentrations of radionuclides in water are developed. If activity concentrations of radionuclides do not exceed these levels, aquatic biota can be considered completely protected from the negative effects of ionizing radiation. Reference concentrations of radionuclides in environmental objects can be compared directly with the measurement data on radioactive contamination parameters that allows using them for the monitoring data interpretation. Reference concentrations of anthropogenic radionuclides in the sea and fresh water are calculated using the environmental criteria and are compared to the values of reference concentrations computed using the hygienic criterion. It is demonstrated that the current levels of concentration of 90Sr, 137Cs, and tritium in the seas, rivers, and lakes of Russia are considerably lower than the values of reference concentrations of these radionuclides calculated using the environmental criterion.

Radiological maps in beach sands along some coastal regions of Turkey

In the present research, the gamma-emitting radionuclides in beach sands along the coastal regions of the Ordu, Giresun and Trabzon provinces, Turkey have been determined. The natural and anthropogenic radionuclide concentrations of the samples have been measured employing a germanium (HPGe) detector with high resolution and purity. The activity for 238U, 232Th, 40K and 137Cs of the samples were found to vary in the range from below detection limit (BDL) to 65Bq·kg−1, from BDL to 28Bq·kg−1, from 9 to 1936Bq·kg−1 and from BDL to 22Bq·kg−1, respectively. The activity concentrations were compared with those in the literature. The associated radiological hazard indices were estimated, and were compared to the internationally recommended values. The radiological map of beach sand in the surveyed area was imaged. The data presented in the study are crucial since they constitute a baseline for the radiological mapping of the region in the future.

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.

A WEIGHT-OF-EVIDENCE APPROACH TO THE ASSESSMENT OF ECOLOGICAL RISK FROM HISTORICAL CONTAMINATION OF OTTAWA RIVER SEDIMENTS NEAR CHALK RIVER LABORATORIES

Canadian Nuclear Laboratories’ Chalk River Laboratories (CRL) site is situated on the banks of the Ottawa River, about 180 km northwest of the City of Ottawa. Since 1947, the Ottawa River has received effluent from CRL’s operations. Since this time, and in particular during the operation of the national research experimental research reactor (1947–1992), radionuclides (mainly 60Co and 137Cs) and mercury released in effluents have accumulated in deep-water sediments downstream of CRL. In the following, we present a holistic summary of characterization of the historical contamination and ecological risk assessment work completed to date. The evaluation included (i) comparisons of recommended benchmark dose and screening levels with concentrations in water and sediment, (ii) determination of relevant exposure pathways and biological receptors, (iii) measured and (or) modelled contaminant exposure to benthic receptors and trophic transfer of contaminants to upper trophic level receptors, (iv) whole-sediment laboratory toxicity tests using benthic invertebrates and fish, and (v) field studies assessing possible intermediate or long-term effects on aquatic biota at the population and community levels. The ecological risk related to the contaminated sediment site was assessed using multiple lines of evidence and a weight-of-evidence approach. Despite concentrations of anthropogenic radionuclides and mercury above screening levels in Ottawa River sediments near CRL, the laboratory toxicity tests, radiological dose and mercury bioaccumulation modelling, and biological surveys of benthic invertebrates and fish indicated no significant adverse effects. Ecological risk to Ottawa River benthic invertebrates, fish, fish-eating birds and mammals from historical sediment contamination near CRL is low-to-negligible, and levels of risk will continue to decline as sediment-bound radionuclides decay and contamination is buried by new sediment.

Radiocesium monitoring in Indonesian waters of the Indian Ocean after the Fukushima nuclear accident

As data on anthropogenic radionuclide concentrations (i.e., 134Cs and 137Cs) in Indonesian marine environments including the Indian Ocean are scarce, offshore monitoring has been performed in the West Sumatra and South Java Seas. The activity concentration of 137Cs ranges from below minimum detectable activity (MDA) to 0.13Bqm−3 in the surface seawater of the South Java Sea and from lower than MDA to 0.28Bqm−3 in the surface seawater of the West Sumatra Sea. The concentrations of 137Cs in the surface seawater of the West Sumatra and South Java Seas are lower than the estimation of 137Cs concentration in the subsurface waters owing to the input of the North Pacific Ocean via the Indonesian Throughflow (ITF). The concentrations of 134Cs in the sampling locations were lower than MDA. These results have indicated that these Indonesian marine waters have not yet been influenced by the Fukushima radioactive release.

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.

Assessment of natural and artificial radionuclides in Mission (Texas) surface soils

Residents in the city of Mission, Texas have been noted to complain of health related problems possibly associated with low dose radiation exposure. The purpose of this study was to quantify radioactivity levels in the entire Mission area by measuring natural and anthropogenic radionuclide concentrations (226Ra, 228Ra, 137Cs) in 30 representative surface soil samples through high-resolution gamma-ray spectroscopy. The activity concentrations of these radionuclides followed an approximately normal distribution across the samples and were found to be comparable to other similar studies. In addition, radiological impact assessment factors were calculated and found to be within the recommended values.

Measurement of the terrestrial and anthropogenic radionuclide concentrations in Bafra Kizilirmak delta (bird sanctuary) in Turkey

In this study, the activity concentrations of terrestrial and anthropogenic radionuclides in the soil samples collected from Bafra Kızılırmak Delta were measured by using gamma spectrometry with an NaI(Tl) detector. The average values of activity concentrations of (238)U, (232)Th and (40)K were found to be 37.2±2.8, 33.7±3.1 and 413.0±59.8 Bq kg(-1), respectively. (137)Cs was also measured in some samples. It has a mean value of 13.8±1.0 Bq kg(-1). From the activity concentrations, the absorbed gamma dose rates in outdoor and the corresponding annual effective dose rates and external hazard index (Hex) were estimated.

NaI(Tl)検出器で測定された波高分布を用いた人工放射性核種濃度の推定

NaI(Tl)検出器で測定された波高分布を用いた人工放射性核種濃度の推定

Anthropogenic Radionuclides in Ottawa River Sediment near Chalk River Laboratories

The Ottawa River has received nuclear reactor effluent from Chalk River Laboratories (CRL) for more than 60 years, including releases from a NRX accident in 1952. Recent interest in the potential impact of these historical releases and the possible need for remediation of a small region immediately downstream from the release point has led to comprehensive studies to assess risk to people and wildlife. In this paper, the results of an extensive survey of gamma-emitting anthropogenic radionuclides in Ottawa River sediment in the vicinity of CRL are presented. Anthropogenic radionuclides detected in Ottawa River sediment include 60Co, 94Nb, 137Cs, 152Eu, 154Eu, 155Eu and 241Am. Concentrations of all anthropogenic radionuclides decline rapidly with distance downstream of the process outfall, reaching stable concentrations about 2 km downstream. All of these radionuclides are found at some sites within 2 km upstream of the process outfall suggesting limited upstream transport and sedimentation. Comparison of anthropogenic radionuclides with several representative primordial radionuclides shows that with the exception of sites at the process outfall and within 2 km downstream of the process outfall, primordial radionuclide concentrations greatly exceed CRL derived anthropogenic radionuclide concentrations. Thus, over 60 years of radionuclide releases from operations at CRL have had little impact on radionuclide concentrations in Ottawa River sediment, except at a few sites immediately adjacent to the process outfall.

Impact of industries in the accumulation of radionuclides in the lower part of Ebro river (Catalonia, Spain)

Ebro River extends over almost 930 km and is the main Spanish river entering the Mediterranean Sea. There are several industries located along this river course including a dicalcium phosphate factory (DCP) and two nuclear power reactors. These installations, together with other factors such as the geology, can contribute to the radiological content of the river. Therefore, this study was performed to determine some natural and also some anthropogenic radionuclide concentrations in the Ebro River ecosystem. We analysed water samples, solid samples (rice field sludge and surface marine sediment samples), and also biota samples ( Cladophora glomerata and Cynodon dactylon ). For water samples, gross alpha, gross beta, tritium, uranium, thorium and also a group of gamma-emitting isotopes’ activities were determined. The main contribution to radioactivity for these samples was due to some isotopes from the uranium and thorium chain. For the solid samples, we quantified some natural and artificial gamma radioisotopes, which may be related to the geological and/or industrial activities located in this zone. In the case of biota, the results indicate that the presence of the DCP has a significant influence, since the highest activity was observed in the surroundings of this industry (Flix), where isotopes such as 214 Bi and 214 Pb presented activity values of 105 ± 43 Bq/kg and 100 ± 58 Bq/kg, respectively.

Arctic Ocean sea ice drift origin derived from artificial radionuclides

Since the 1950s, nuclear weapon testing and releases from the nuclear industry have introduced anthropogenic radionuclides into the sea, and in many instances their ultimate fate are the bottom sediments. The Arctic Ocean is one of the most polluted in this respect, because, in addition to global fallout, it is impacted by regional fallout from nuclear weapon testing, and indirectly by releases from nuclear reprocessing facilities and nuclear accidents. Sea-ice formed in the shallow continental shelves incorporate sediments with variable concentrations of anthropogenic radionuclides that are transported through the Arctic Ocean and are finally released in the melting areas. In this work, we present the results of anthropogenic radionuclide analyses of sea-ice sediments (SIS) collected on five cruises from different Arctic regions and combine them with a database including prior measurements of these radionuclides in SIS. The distribution of 137Cs and 239,240Pu activities and the 240Pu/ 239Pu atom ratio in SIS showed geographical differences, in agreement with the two main sea ice drift patterns derived from the mean field of sea-ice motion, the Transpolar Drift and Beaufort Gyre, with the Fram Strait as the main ablation area. A direct comparison of data measured in SIS samples against those reported for the potential source regions permits identification of the regions from which sea ice incorporates sediments. The 240Pu/ 239Pu atom ratio in SIS may be used to discern the origin of sea ice from the Kara–Laptev Sea and the Alaskan shelf. However, if the 240Pu/ 239Pu atom ratio is similar to global fallout, it does not provide a unique diagnostic indicator of the source area, and in such cases, the source of SIS can be constrained with a combination of the 137Cs and 239,240Pu activities. Therefore, these anthropogenic radionuclides can be used in many instances to determine the geographical source area of sea-ice.

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.

Recent trends of environmental radioactivity in Greenland and the Faroe Islands

Environmental radioactivity in Greenland and the Faroe Islands was investigated from samples collected in 2004 of seawater, seaweed, marine fish, seal, whale, lake water, freshwater fish and total diet. Anthropogenic radionuclides in Greenland and the Faroe Islands are present due to long-range transport by air and water mainly due to fallout from nuclear weapons testing, from the Chernobyl accident and discharges from European reprocessing facilities, Sellafield in the UK and La Hague in France. Concentrations of anthropogenic radionuclides in environment and food are low, however, and present insignificant health risks to humans. Naturally occurring radionuclides are present in the environment and human food and dominate the radiation dose from ingestion. Even in case of landlocked Arctic char from South Greenland showing elevated concentrations of anthropogenic 137 Cs, the radiation doses to man from ingestion derive mainly from the presence of the naturally occurring radionuclide 210 Po. Samples of total diet from Uummannaq indicate that annual radiation doses by ingestion could approach 1 mSv from 210 Po possibly due to a high proportion of seal flesh and liver in the diet.

Global distribution of radionuclides (137Cs and 40K) in marine mammals.

Concentrations of anthropogenic radionuclides were measured in the muscle of marine mammals collected from various locations all over the world, and the global distribution of 137Cs in marine mammals was investigated. 40K was detected in all the specimens of marine mammals with no apparent difference between regions. An anthropogenic radionuclide, 137Cs, was detected in most of the species of marine mammals. With regard to the worldwide distribution of 137Cs, the highest concentration was noticed in the U.K. coast, followed by Lake Baikal, and decreases toward the southern sampling points. A strong positive correlation was observed between 137Cs levels in the muscle of marine mammals and the ambient seawater. Marine mammals feeding on fishes showed a higher concentration factor (CF) for 137Cs than those feeding on cephalopods. To our knowledge, this is the first report on the global distribution of 137Cs and the effect of feeding habits on the CF values of 137Cs in marine mammals.