Determination of137Cs,90Sr and fallout Pu in the volcanic soil of Korea

The cumulative depositions of¹³⁷Cs,⁹⁰Sr and fallout Pu in the volcanic ash soil of Korea were determined. The average accumulated depositions of¹³⁷Cs,⁹⁰Sr and fallout Pu in the volcanic soil were much higher than those in other forest sites of Korea. From depth profiles, it was found that¹³⁷Cs,⁹⁰Sr and^239,240Pu in the volcanic soil are more mobile than those in other forest sites of Korea, and that the downward movement of⁹⁰Sr is faster than¹³⁷Cs and^239,240Pu. A significant correlation was found between the concentration of¹³⁷Cs and those of⁹⁰Sr and^239,240Pu. The activity ratios of²³⁸Pu/^239,240Pu and²⁴¹Pu/^239,240Pu in soils are close to those observed in the cumulative deposit from the global fallout of nuclear weapon testings.     

Artificial radioactive contamination of sediment samples along the Romanian sector of the Danube river and the Black Sea coast

The concentrations of¹³⁷Cs were determined by in 11 sediment samples, collected along the Romanian sector of the Danube river and the Black Sea coast during 1994 γ-ray spectrometry. The concentrations of⁹⁰Sr in the same sediment samples were determined by β-counting of the⁹⁰Y oxalate, precipitated after strontium separation using a strontium extraction chromatography column. The concentration distributions of¹³⁷Cs and⁹⁰Sr are compared with the²³⁸Pu and^239,240Pu concentration distributions in the same samples, reported in a previous paper. The accumulation potential of¹³⁷Cs,⁹⁰Sr and plutonium isotopes in the river and sea sediments analysed is discussed.     

210Pb fluxes in sediment layers sampled from Northern Patagonia lakes

Unsupported ²¹⁰Pb fluxes were determined from sediment core inventories in lakes located in Northern Patagonia, Argentina. Total ²¹⁰Pb, ²²⁶Ra, associated with supported ²¹⁰Pb, and ¹³⁷Cs specific activity profiles were measured by gamma-ray spectrometry. Unsupported ²¹⁰Pb fluxes showed very low values when compared to other regions, with a 12 fold variation, ranging from 4 to 48 Bq m^–2.y^–1. The linear correlation observed between the ²¹⁰Pb fluxes and¹³⁷Cs cumulative fluxes in sediment cores sampled from water bodies within a zone with similar precipitation demonstrated that both radioisotopes behave in the same manner in these systems concerning the processes occurred from fallout to sediment deposition, and that there are no appreciable local or regional sources of unsupported ²¹⁰Pb. Positive correlation of ²¹⁰Pb fluxes with organic matter contents of the uppermost sediment core layers was also observed.     

Separation of137Cs and90Sr from mineralizates of biological materials by dicarbolide of cobalt

The distribution of some radionuclides in the course of¹³⁷Cs and⁹⁰Sr extraction and scrubbing between organic and water phase was determined.¹³⁷Cs and⁹⁰Sr were isolated from the mixture of radionuclides in mineralized biological materials. Dicarbolide of cobalt i. e. 3,3′-commo-bis[undecahydro-1,2-dicarbo-3-closo-dodecaborate] was used as an extracting agent. Quantities of the extracted radionuclides were determined by gamma spectrometric technique. Single and repeated extraction of⁹⁰Sr with 0.01M resp. 0.1M dicarbolide of cobalt in nitrobenzene and scrubbing of coextracted radionuclides by 0.5M HNO₃ were studied. The extraction of⁹⁰Sr was investigated from solutions of a hydrofobizing agent in the same way. Finally, the quantitative extraction of¹³⁷Cs followed by the extraction of⁹⁰Sr from mixtures of radionuclides in a mineralized biological material was studied. Extraction yields from dry and wet mineralizates of biological tissues, from urine and milk were compared. Suitable working conditions for the separation procedures were selected.     

Mixing of atmospheric <Superscript>210</Superscript>Pb and <Superscript>7</Superscript>Be and <Superscript>137</Superscript>Cs and <Superscript>90</Superscript>Sr fission products in four characteristic soil types

Depth distribution of atmospheric ²¹⁰Pb and ⁷Be and ⁹⁰Sr and ¹³⁷Cs fission products was measured in two types of aeolian soils (desert dust and volcanic ash), irrigated paddy soil and strongly acidic soil. The depth dependence of ²¹⁰Pb, ⁷Be and ¹³⁷Cs show that these radionuclides have been diffused as solid soil particles in surface soil layers. In aeolian soil layers, about 50% of ⁹⁰Sr were diffused in surface soil layer and the remaining 50% had penetrated to deeper layers. The half of the fission particles containing ⁹⁰Sr were shown to have decomposed over the past 35 years.     

A study on radionuclide association with soil components using a sequential extraction procedure

Measurements performed in 1986–1988 demonstrate that most of the radiocesium isotopes (¹³⁷Cs and¹³⁴Cs) deposited after the Chernobyl accident are still located in the upper soil layers (0–2 cm). The vertical migration appears to be slow, and only a small fraction of the radiocesium has been transferred into the biological cycle. Sequential extraction techniques have been utilized in order to investigate the degree of binding or association between deposited radionuclides (¹³⁷Cs,¹³⁴Cs and⁹⁰Sr) and components in soil. The results indicate that a major fraction of the radiocesium is associated strongly with organic and mineral materials in the litter or upper soil layers: less than 10% is easily leachable. The distribution of¹³⁷Cs throughout the fractions was similar to that determined for naturally occurring stable cesium (¹³³Cs), implying that isotopic exchange had been extensive. For⁹⁰Sr, the results show a relatively high leachable fraction. Therefore, present results indicate that radiocesium should be less mobile, and less available for root uptake, than⁹⁰Sr in soil.     

Sedimentation rate in the Sungai Linggi estuary using excess 210Pb and 137Cs

The purpose of this study was to estimate the sedimentation rate in the Sungai Linggi estuary using the constant initial concentration of unsupported or excess ²¹⁰Pb model and verified with ¹³⁷Cs method. Five sediment cores were collected on 25 January 2011 using gravity corer with the inner tube of 50 cm length and 7.5 cm diameter. The total ²¹⁰Pb activities in the sediment cores profile at all sampling stations were varied and upper than those obtained for supported ²¹⁰Pb i.e. ²²⁶Ra, indicated disequilibrium among ²¹⁰Pb and its grandparents in the ²³⁸U decay series. Meanwhile, the lower ¹³⁷Cs activities were observed at all sampling stations due to no significant sources of ¹³⁷Cs releases were transferred into Malaysian marine. The estimation of sedimentation rate indicated the agreement of ²¹⁰Pb and ¹³⁷Cs method with a general presence of deep mixing in the Sungai Linggi estuary. Therefore, the apparent sedimentation rates calculated from ²¹⁰Pb profiles generally reflect the true value with the range from 0.70 to 1.97 cmyr^?1. High sedimentation rate was observed at some sampling stations which are located in river channel, estuary and closer to mainland. This suggested that land-use development, agriculture activities, channelization etc. introduced a large amount of sediment loaded into those areas.     

Determination of90Sr and137Cs in mushrooms following the Chernobyl fallout

After the Chernobyl accident high concentrations of radionuclides were found in Sweden in mushrooms and the contents of⁹⁰Sr and¹³⁷Cs were measured. The level of⁹⁰Sr was generally low and, in proportion to¹³⁷Cs, 2–3 orders of magnitude lower than in the fallut. The contents of¹³⁷Cs varied among species and extreme local variations occurred. The ratio¹³⁴Cs/¹³⁷Cs diverged from other biological samples leading to the conclusion that old fallout was involved in the uptake.     

137Cs dating of lake cores from the Nahuel Huapi National Park, Patagonia, Argentina: Historical records and profile measurements

Historical records of short lived (¹⁴⁰Ba, ¹³¹I, ¹⁰³Ru and ⁹⁵Zr+⁹⁵Nb) and long-lived (¹³⁷Cs and ⁹⁰Sr) fission products by fallout measurements performed in Argentina since 1959 were analyzed in order to define the main characteristics of ¹³⁷Cs fallout time evolution in the Nahuel Huapi National Park, Patagonia, Argentina. Sedimentary cores were sampled from Lake Nahuel Huapi and Lake Morenito, which are located within Nahuel Huapi National Park. ¹³⁷Cs specific activity profiles were measured and ²¹⁰Pb dating was performed in each core. The time evolution of ¹³⁷Cs fallout shows different characteristics than records taken in the Northern Hemisphere.¹³⁷Cs specific activity profiles of the cores studied reproduce the fallout time sequence observed in the historical records, and the chronology obtained shows excellent agreement with ²¹⁰Pb dating.     

Sequential estimation of106Ru,137Cs,and90Sr in urine

A sequential method has been developed for the estimation of¹⁰⁶Ru,¹³⁷Cs, and⁹⁰Sr in urine using beta counting. After completely destroying the organic matter in urine,¹⁰⁶Ru is oxidized to volatile ruthenium tetroxide and allowed to reactin-situ with polyethylene powder;¹³⁷Cs is concentrated on ammonium phosphomolybdate and estimated as tetraphenylborate;⁹⁰Sr is coprecipitated as strontium sulphate and converted to carbonate. The recoveries have been found to be better than 83% for all of the radionuclides. The minimum detection limits are 0.16, 0.85, and 0.14 Bq/dm³ for¹⁰⁶Ru,¹³⁷Cs, and⁹⁰Sr, respectively. Yttrium-90 fraction of⁹⁰Sr is also estimated using sodium nitroprusside as reagent, after allowing it to grow for 14 days.This work forms part of the doctoral work of SRIM.V.R. PRASAD to be submitted to the University of Madras, under the supervision of DR. O.M. SREEDHARAN.     

Concentrations of108mAg,137Cs,and210Pb in oyster (Crassostrea gigas) on the Japanese coast in relation to the distribution and behavior of radionuclides in sea water

Concentrations of^108mAg,¹³⁷Cs, and²¹⁰Pb in oysters (Crassostrea gigas) were measured for about 10 years on the northeast coast of Japan. Silver-108m was detected in oyster samples collected from an open bay, and its concentrations decreased from the initial value of about 30 mBq/kg fresh in the early 1980s to the value of about 10 mBq/kg fresh in the early 1990s. This decrease could be mainly explained by effects of the ocean current in the early 1980s, and the coastal sea water thereafter, as well as by the advection and diffusion in the ocean. In the nearly-closed bays, concentrations of^108mAg and²¹⁰Pb in oysters were remarkably lower than in the open bays. It suggests that scavenging of silver and lead from the sea water effectively occurred in the nearly-closed bays. In contrast, concentrations of¹³⁷Cs in oysters were similar in the open bays and in the nearly-closed bays.     

Studies of the vertical distribution of134Cs,137Cs,238Pu,239, 240Pu,241Pu,241Am and210Pb in ombrogenous mires at mid-latitudes

Six peat cores taken from three unmodified blanket and raised bogs in Ireland were sectioned and analyzed for a range of radionuclides including¹³⁴Cs,¹³⁷Cs,²³⁸Pu,²³⁹Pu,²⁴¹Am, and²¹⁰Pb.¹³⁴Cs and¹³⁷Cs were measured by high resolution gamma-spectrometry, while the transuranium nuclides were determined after chemical separation by alpha-spectrometry.²⁴¹Pu, present on the electroplated discs together with Pu(), was measured directly by low-level liquid scintillation counting. Core chronologies were established by measuring the unsupported²¹⁰Pb component using low energy photon spectrometry (LEPS). From the resulting profiles, relaxation depths and migration rates for the above mentioned radionuclides have been determined and differences in the values of these parameters interpreted.²³⁸Pu/^239,240Pu and²⁴¹Pu/^239,240Pu ratios have been examined carefully and are discussed in some detail. Finally, the contribution from Chernobyl to the total radiocaesium inventory in each core has been established using the¹³⁴Cs/¹³⁷Cs ratio observed in the initial fallout from Chernobyl.     

Heavy metal inputs in Northern Patagonia lakes from short sediment core analysis

Summary Heavy metal profiles of short sediment cores sampled from lakes located in Nahuel Huapi National Park, Northern Patagonia, Argentina, were determined by INAA. Core dating was performed by measuring natural ²¹⁰Pb and anthropogenic ¹³⁷Cs, and by identification of tephra layers. No evidence was found for the input increase of the trace elements Sb, Ba, Cs, Zn, Co, Hf, Ni, Se, Sr, Ti, U, and V in the lake environment. High As concentrations (up to 250 μg ^. g^-1) were found in relation with the diffusion processes of Mn and Fe oxides. Strong correlation was observed between the Br concentration and organic matter content, but no evidence was found for the relevant increase of Br inputs in recent years. Ag concentrations were found to be enriched in the upper core layers over the baseline values determined for deep layers ranging from 0.1 to 0.2 μg ^. g^-1. Hg concentration profiles were also enriched in the upper core layers over the baseline (from less than 0.07 to 0.2 μg ^. g^-1 for pre-industrial time, to 0.1 to 0.3 μg ^. g^-1 for modern times) but in relation with the increased organic matter content of the sediment.     

Radiochronology of sediments from the Mediterranean Sea using natural210Pb and fallout137Cs

The²¹⁰Pb and¹³⁷Cs profiles of sediment cores from two locations in southern Spain, three locations in southern Turkey and two locations in northern Cyprus were determined by direct -ray spectroscopy. Sedimentation rates were derived for all locations using the²¹⁰Pb data. The rates range from 1.39±0.12 cm · y^–1 (0.50±0.04 g · cm^–2 · y^–1) to 0.08±0.01 cm · y^–1 (0.039±0.003 g · cm^–2 · y^–1). Except for one core, the¹³⁷Cs profiles were also used to compute sedimentation rates. The results are in good agreement with those of²¹⁰Pb values. The results of the Constant Initial Concenration and Constant Rate of Supply dating models are in good agreement with each other. The flux of unsupported²¹⁰Pb varies between 0.11±0.03 to 0.74±0.01 pCi · cm^–2. The average depositional flux was found to be considerably lower for cores from the Eastern Mediterranean.     

Environmental radioactivity in Romania Danube river area during 1986–1990

This paper presents the results of radioactivity studies of environmental factors such as surface water, sediment, aquatic vegetation and soil. The concentrations of¹³⁷Cs,⁹⁰Sr,³H, U, Ca, and Mg in water samples were determined by radiochemical and chemical methods. Gamma-spectrometric analyses were performed for all the samples. The analysis showed a decrease in concentrations of¹³⁷Cs in water, aquatic vegetation and sediment, but a constant level of¹³⁷Cs activity in soil (0–5 cm depth). The average concentrations of⁹⁰Sr,³H, U, Ca and Mg were about 7 mBq/l, 11 Bq/l, 0.6 g/l 60 mg/l and 11 mg/l, respectively.     

Surface and depth fallout distribution of137Cs and90Sr in soils of Caceres (Spain). Dose commitments due to external irradiation

An analysis has been made of the surface distribution of¹³⁷Cs and⁹⁰Sr in soils of the province of Cáceres (Spain), of some 20.000 km² area, situated on the frontier with Portugal. From the distribution of depth profiles of concentrations of these radionuclides and their fit to a negative exponential, determination was made of the mean values of the respective inventories and of the corresponding¹³⁷Cs/⁹⁰Sr ratio. The external dose rates from the presence of these man-made isotopes in the soil are calculated and compared with that originating from the concentrations of natural radioisotopes.     

Measurements of210Pb,137Cs,organic carbon and trace elements in sediments of the Illinois and Mississippi rivers

Radiometric dating of sediment accumulations by¹³⁷Cs and²¹⁰Pb has been successfully initiated in the Illinois and Mississippi Rivers. Sedimentation rates measured at 13 locations range from 0.7 to 3.6 cm/y. Chemical analysis has been completed for up to 45 major and trace elements in core samples. The upper Illinois River contains higher metal levels than the Mississippi River. The amount of carbon (energy) lost to sediments in large floodplain rivers is estimated between 370 and 4000 g/m²/y.     

Detection of fallout155Eu and207Bi in a210Pb-dated lake sediment core

Low-energy -ray spectrometry is used to detect fallout¹⁵⁵Eu and²⁰⁷Bi in a²¹⁰Pb-dated sediment core from McKay Lake, Ottawa, Canada. Unlike²⁰⁷Bi which is detected only in two core sections deposited in the mid 1970's,¹⁵⁵Eu is consistently detectable to mid 1960's. A comparison of corresponding¹³⁷Cs and¹⁵⁵Eu inventories in the sediment core indicates that fallout¹⁵⁵Eu derives primarily from the thermal neutron fission of²³⁵U. The derived flux of unsupported²¹⁰Pb at the sediment/water interface is in agreement with previously estimated flux of atmospheric²¹⁰Pb in the Great Lakes region.     

Atmospheric residence times of strontium-90 and lead-210

The concentrations of⁸⁹Sr,⁹⁰Sr,²¹⁰Pb and²¹⁰Po were measured in a series of rain samples collected at Fayetteville (36°N, 94°W), Arkansas, after the 14th Chinese test of March 18, 1972, which occurred at Lop Nor (40°N, 90°E), China. Approximately concordant tropospheric residence times were obtained from the⁸⁹Sr/⁹⁰Sr and²¹⁰Po/²¹⁰Pb ratios in rain. The⁸⁹Sr/⁹⁰Sr ratios were also measured for the rain samples collected at Tokyo (36°N, 140°E), Japan, and at Ankara (40°N, 33°E), Turkey.     

Radioanalytical determination of137Cs and89Sr in milk

Separation of Cs, Sr and Ca from their mixture was studied using solvent extraction and ion exchange techniques. More than 90% separation efficiency was achieved for Ca–Sr separation using ion exchange resin (Doulite C-20) while solvent extraction amounted to 88%. A proposed technique for determination of¹³⁷Cs and⁸⁹Sr in milk (after removal of organic matter) showed more than 80% accuracy for⁸⁹Sr determination and more than 90% for¹³⁷Cs determination.