Activity Concentrations Of Artificial Radionuclides Research Articles

Artificial Radionuclides in the System: Water, Irrigated Soils, and Agricultural Plants of the Crimea Region

In the frame of the radioecological monitoring after the Chernobyl nuclear power plant accident, the features of migration and distribution of artificial radionuclides in the North Crimean Canal (NCC) irrigation system were studied. Standard methods of radiochemical analyzes and modern radiospectrometric equipment were used. It was determined that the irrigation system of the NCC retains 43–59% 90Sr, 59–60% 239+240Pu, and 66–70% 137Cs of the concentration radionuclides entering to irrigated fields with the Dnieper waters. The NCC irrigation system plays the role of a buffer against the radionuclide pollution of the Karkinitsky Bay (the Black Sea). Differences in the accumulation of radionuclides by agricultural crops were revealed. The 90Sr and 239+240Pu transfer factors (TF) for alfalfa were n × 10−2 and n × 10−1, respectively. The TF for wheat, corn, and rice for 90Sr were n × 10−3, and for 239+240Pu—n × 10−2. A radioecological assessment on the safety agriculture along the NCC was made: in the absence of an increase in the entry of the Chernobyl origin radionuclides with the Dnieper river waters to the NCC, the levels of activity concentration of artificial radionuclides in cultivated crops will not exceed the maximum permissible concentration for food raw materials in the coming years.

Assessment of residual radionuclide levels at the Bokak and Bikar Atolls in the northern Marshall Islands

The Bikar and Bokak Atolls, located in the northern Marshall Islands, are extremely isolated and consist of pristine marine and terrestrial ecosystems. Both atolls may have experienced significant radioactive deposition following the nuclear weapon testing conducted at Bikini and Enewetak proving grounds. Here we report activity concentrations of artificial radionuclides (239Pu, 240Pu, 241Pu, 241Am, 137Cs and 90Sr) in marine and terrestrial samples collected from Bikar and Bokak Atolls. Artificial radionuclides in soil from the Majuro Atoll are also reported and form a radiological baseline against which the levels at the other atolls can be compared. We observed low levels of artificial radionuclides in soil from Majuro and Bokak, but significantly higher levels in soil from Bikar. The residual radioactivity in the Bikar environment is comparable to the levels previously reported for other nearby atolls, including Taka and Utrik, but lower than for Rongerik, Rongelap, Bikini and Enewetak. An analysis of 240Pu/239Pu isotope ratios and estimations of the dates of contamination from 241Am/241Pu activity ratios both indicated that the Bikar Atoll was contaminated mainly by radioactive fallout from the Castle Bravo test in 1954. We compare the results of our measurements at Bikar and Bokak to data from other atolls in the Marshall Islands and to regions of the world affected by both global and regional fallout from atmospheric nuclear weapons testing and nuclear accidents.

Monitoring of radionuclides in the surface soil around the Jordan Research and Training Reactor (JRTR) before commissioning

The present investigation creates a baseline of radioactivity and radiation levels around the Jordan Research and Training Reactor (JRTR) before Commissioning. It can be utilized to correlate the radioactivity measured after the operation of the reactor. The activity concentrations of artificial radionuclides (134Cs, 137Cs and 60Co) and natural (40K) radionuclides have been measured with a γ-ray spectrometer based on a high purity germanium detector (HPGe) for eighteen surface soil samples from various locations around the JRTR. The average concentration of radionuclides 40K was found to be (340.3 ± 16.3) Bq/kg, and artificial radionuclides 137Cs have been detected at thirteen locations around JRTR with activity concentration varies between (2.94 ± 0.41) and (25 ± 0.8) Bq/kg while no traces of 134Cs and 60Co detected in the locations of interest. The results of this investigation will form the baseline for future monitoring of radiological impact around the JRTR after commissioning.

The English Channel: Contamination status of its transitional and coastal waters

The chemical contamination (organic compounds, metals, radionuclides, microplastics, nutrients) of English Channel waters has been reviewed, focussing on the sources, concentrations and impacts. River loads were only reliable for Pb, whereas atmospheric loads appeared robust for Cd, Pb, Hg, PCB-153 and γ-HCH. Temporal trends in atmospheric inputs were decreasing. Contaminant concentrations in biota were relatively constant or decreasing, but not for Cd, Hg and HBCDD, and deleterious impacts on fish and copepods were reported. However, data on ecotoxicological effects were generally sparse for legacy and emerging contaminants. Intercomparison of activity concentrations of artificial radionuclides in sediments and biota on both Channel coasts was hindered by differences in methodological approaches. Riverine phosphate loads decreased with time, while nitrate loads remained uniform. Increased biomass of algae, attributable to terrestrial inputs of nutrients, has affected benthic production and shellfisheries. A strategic approach to the identification of contaminant impacts on marine biota is recommended.

Technogenic radionuclides in undisturbed Bulgarian soils

This work presents data for the activity concentration of artificial radionuclides in soils from different regions in Bulgaria for the period 1985–2011. The subjects of the study were undisturbed soils from mountainous, hilly, and plain areas. Special attention has been paid to the contamination with the long-lived technogenic radionuclides cesium-137, strontium-90, plutonium-238, and plutonium-239+240. 137Cs was measured by low level gamma spectrometry and 90Sr by radiochemical separation and low level beta counting. The isotopes of plutonium were measured by alpha-spectrometry after a radiochemical procedure of purification and concentration.Cesium-137 and strontium-90 were the main technogenic radionuclides detected in the examined Bulgarian soils few years after the Chernobyl NPP accident. Their content in the soils from high mountain areas is several times higher than that in the soils from the plane areas in the northern part of the country. High heterogeneity in the pollution has been observed. Mean soil activity concentration levels of up to 250Bqkg−1 for 137Cs and 14Bqkg−1 for 90Sr were found in different years. The maximal values registered in separate soil samples were about 1300Bqkg−1 (137Cs) and 24Bqkg−1 (90Sr). The activity concentration levels for 239+240Pu varied between 0.1 and 3.7Bqkg−1. The results indicate that the radioactive pollution of the Bulgarian soils with artificial radionuclides is a result of global fallout and Chernobyl nuclear power plant accident.

Environmental radioactivity measurements in Greece following the Fukushima Daichi nuclear accident

Since the double disaster of the 9.0 magnitude earthquake and tsunami that affected hundreds of thousands of people and seriously damaged the Fukushima Daichi power plant in Japan on 11 March 2011, traces of radioactive emissions from Fukushima have spread across the entire northern hemisphere. The radioactive isotope of iodine (131)I that was generated by the nuclear accident in Fukushima arrived in Greece on 24 March 2011. Radioactive iodine is present in the air either as gas or bound to particles (aerosols). The maximum (131)I concentrations were measured between 3 and 5 April 2011. In aerosols the maximum (131)I values measured in Southern Greece (Athens) and Northern Greece (Thessaloniki) were 585±70 and 408±61 μΒq m(-3), respectively. (131)I concentrations in gas were about 3.5 times higher than in aerosols. Since 29 April 2011, the (131)I concentration has been below detection limits. Traces of (137)Cs and (134)Cs were also measured in the air filters with an activity ratio of (137)Cs/(134)Cs equal to 1 and (131)I/(137)Cs activity ratio of about 3. Since 16 May 2011, the (137)Cs concentration in air has been determined to be about the same as before the Fukushima accident. Traces of (131)I were also measured in grass and milk. The maximum measured activity of (131)I in sheep milk was about 2 Bq l(-1) which is 5000 times less than that measured in Greece immediately after the Chernobyl accident. The measured activity concentrations of artificial radionuclides in Greece due to the Fukushima release, have been very low, with no impact on human health.

Artificial radionuclides in sediment of the Yenisei River

Releases from the nuclear facility Mining-and-Chemical Combine (MCC) located at Zheleznogorsk have contributed to the radionuclide contamination of the Yenisei River since operations commenced in 1958. The aim of this study was to assess the activity concentrations of artificial radionuclides and the strength of their binding in Yenisei River sediments. Investigation of Yenisei River sediment samples revealed the presence of artificial radionuclides typical of the MCC radioactive discharge: namely, isotopes of europium, caesium, 60Co and transuranium elements. The concentrations of artificial radionuclides in the sediment layers remain relatively high as far as 200 km downstream of the MCC. In sediment cores collected upstream of the MCC, γ-spectrometric measurements registered only one artificial radionuclide, 137Cs, with a maximal activity of 8 Bq·kg−1. Sequential extraction performed on samples of the upper layers of the sediment core showed different degrees of potential environmental availability for artificial radionuclides: the highest was recorded for 241Am and 152Eu (up to 85% of initial activity), followed by 60Co (up to 32%), and finally, 137Cs (up to 15%). In a few samples, 241Am was present in the unextractable form, which may be accounted for by the presence of reactor fuel microparticles.