Measurement of210Pb from a sediment core off the coast of California

Measurements of²¹⁰Pb at various dephts in a sediment core from the Santa Cruz Basin off the coast of California have been made. The radiochemical separation of²¹⁰Pb was carried out after ashing the sediment at 400 °C. The activities of the purified²¹⁰Pb was assayed in a low background beta counter by counting the 1.17 MeV betas of its daughter product²¹⁰Bi. The method for the chemical separation of²¹⁰Pb and the results are discussed in the paper.     

Metal contamination in Sunairi Point sediment core along Karachi coast,Pakistan

Journal of Radioanalytical and Nuclear Chemistry - This paper describes the pollution level in sediment core collected from Sunairi Point of Karachi coastal area Pakistan. The sediment was...     

Radioactivity concentrations in sediment and mussel of Bosphorus and Golden Horn

In the present study, mussel (Mytilus galloprovincialis, Lamarck, 1819) and sediment samples were collected from the Bosphorus strait and the Golden Horn estuary in 2008 and 2009. Activity concentrations of ¹³⁷Cs, ⁴⁰K, ²³²Th and ²³⁸U were measured using a gamma spectrometer equipped with HPGe detector. Sediment samples were separated into <63 μm and >63 μm particle fractions. Analysis of radionuclides was carried out on these two fractions of sediment as well as the soft and shell tissues of mussels. Ranges of radioactivity concentrations in the soft parts of mussels were as follows: ¹³⁷Cs, 0.86–2.43; ⁴⁰K: 261.1–496.7; ²³²Th: 0.49–3.58; and ²³⁸U: BDL (below detection limit)-1.38 Bq kg⁻¹ in dry weight. Ranges of radioactivity concentrations in the <63 and >63 sediment fractions were as follows: ¹³⁷Cs, 8.58–67.92 and 1.12–26.40, ⁴⁰K, 341.4–683.0 and 281.9–662.2; ²³²Th, 10.97–20.16 and 7.18–19.18 and ²³⁸U, 13.97–27.25 and 6.41–18 Bq kg⁻¹ in dry weight, respectively. The effect of some physical–chemical parameters on the radionuclide accumulation was also examined in the sediment samples. All data in the current study were compared with data in the literature.     

Study on the spatial distribution of 137Cs content in bottom sediment and benthic species of Mumbai off coast

The observed ¹³⁷Cs content in bottom sediment and benthic species of Mumbai off coast varied between 2–370  \( {\text{Bq kg}}_{{ ( {\text{dry)}}}}^{ - 1} \) and <0.08–0.4  \( {\text{Bq kg}}_{{ ( {\text{wet)}}}}^{ - 1} \) respectively. The annual estimated ingestion dose to ‘general public’ due to consumption of benthic species is 0.02 µSv y^?1, which is infinitesimally smaller, in comparison to average annual human exposure of 3.01 mSv and also to the internationally accepted public dose limit of 1,000 µSv y^?1.     

Polonium concentration distribution in bed load sediment samples along the Romanian sector of the Danube river and the Black Sea coast

The concentrations of²¹⁰Po have been determined in 12 sediment samples collected from the bed of the Romanian Danube river and the Black Sea coast during June–September 1994. After the sample preparation and the addition of the²⁰⁸Po tracer, polonium was coprecipitated with manganese dioxide, the precipitate was dissolved in hydrochloric acid and the polonium isotopes deposited on silver planchettes were counted by -spectrometry. The resolution of the subsequent -spectra was typically 40 to 60 keV full-width-half-maximum with 450 mm² silicon surface-barrier detectors at 30% counting efficiency. The procedure is quite fast, giving chemical yields between 60 and 80%. The²¹⁰Po concentrations range between 5 and 73 Bq kg^–1 dry, showing for the first time the polonium contamination distribution along the Romanian sector of the Danube river and the Black Sea coast.     

Plutonium concentration distribution in bed load sediment samples along the Romanian sector of the Danube river and the Black Sea coast

The concentrations of²³⁸Pu and^{239, 240}Pu were determined in 12 sediment samples collected from the bed of the Romanian Danube river and Black Sea coast during June–September 1994. After the sample material has been properly prepared and²⁴²Pu tracer added, plutonium was separated from americium and curium by anion exchange. After electrodeposition on stainless steel discs the elements were counted with an -spectrometry system with silicon surface-barrier detectors. The^{239, 240}Pu concentrations range between 150 and 800 mBq kg^–1 dry, while the²³⁸Pu concentrations rise up to max 150 mBq kg^–1 dry. Although the chemical yields are rather low (51%) we appreciate the results as valuable since they report for the first time the distribution of the plutonium contamination along the Danube river and the Black Sea coast-Romanian sector.     

Radionuclides in a sediment trap and bottom sediment samples from the eastern Turkish coast of the Black Sea

Summary Radionuclide (¹³⁷Cs, ²³⁸U, ²³²Th and ⁴⁰K) concentrations were determined in a sediment trap and bottom sediment samples collected from a station at the eastern Turkish coast of the Black Sea. The specific activity of the ¹³⁷Cs radionuclide in the settling particles ranged from 0.04±0.01 to 0.10±0.02 Bq^. g^-1dry weight. The calculated flux rate of the ¹³⁷Cs was between 0.37 and 2.59 Bq^. m^-2. d^-1in the sampling periods of 2002 and 2003. The ¹³⁷Cs concentration in the bottom sediment profile were between 0.039±0.013-9.083±0.017 Bq^. g^-1dry weight in the same station. The vertical profile of the radionuclides suggests that they have little mobility during the 17 years after the Chernobyl accident.     

Radioactivity in the Exclusive Economic Zone of east coast Peninsular Malaysia: distribution trends of <Superscript>137</Superscript>Cs in surface seawater

Large volumes of surface seawater samples were collected from thirty locations in the Exclusive Economic Zone (EEZ) of the east coast Peninsular Malaysia on June 2008 to study the activity concentrations of ¹³⁷Cs. The results will serve as additional information to the existing baseline data and is very useful for monitoring fresh input of anthropogenic radionuclide into Malaysian marine environment. In this study, the activity concentrations of ¹³⁷Cs were determined using co-precipitation technique, followed by Gamma Spectrometry measurement. The mean activity concentration of ¹³⁷Cs ranged between 3.40 and 5.89 Bq/m³. Higher activity concentrations were observed at the coastal and towards the south of Peninsular Malaysia and were aligned with the high turbidity. These may due to the rapid diffusion of ¹³⁷Cs from suspended particulates and fine sediments into surface seawater. The activity concentrations of ¹³⁷Cs observed in this study were slightly higher than the concentrations reported in seawater at the Straits of Malacca, Vietnam and Philippines. This might be because the study area received more input of ¹³⁷Cs that originated from global fallout and then deposited on land which later being transported subsequently into the coastal zone due to siltation and erosion processes. It could also be attributed to the intrusion of river waters containing higher concentrations of ¹³⁷Cs.     

Radioactivity of plutonium isotopes, <Superscript>137</Superscript>Cs 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.     

Radioactivity distribution measurement of various natural material surfaces with Imaging Plate

Distribution images of natural radioactivity in natural materials such as vegetables were obtained by using Imaging Plate. In such cases, it is necessary to reduce background radiation intensity by one order or more. Graded shielding is very important. Especially, the innermost surface of a shielding box should be covered with acrylic resin plate. We obtained natural radioactivity distribution images of vegetables, sea food, meat etc. Mostly -rays emitted from⁴⁰K print the radioactivity distribution image. Comparison between -ray intensity of KCl solution measured with HPGe detector and that of natural material specimen gave the radioactivity around 0.060.4 Bq/g depending on the kind and the part of specimens.     

Conductometric estimation of thorium in dilute thorium chloride

Summary Conductometric titrations of thorium chloride against oxalic acid, ammonium oxalate and silver nitrate have been carried out at high dilutions (0.001, 0.0005 and 0.00033 M) of the chloride. Oxalic acid is found to be a suitable titrant for rapid estimation of thorium, the minimum error being +0.5%. The other titrants do not give good results. The titrations with ammonium oxalate indicate the step-wise ionisation of ThCl₄ into ThCl₂ ²⁺, ThCl³⁺ and Th⁴⁺. For mixtures of thorium chloride and cerous chloride, only the equivalence point corresponding to complete precipitation of both thorium and cerium is indicated.The authors express their sincere thanks to Prof. S. S.Joshi for his keen interest in this work and to Dr. G. S.Deshmukh for his advice and help in so many ways during the progress of these studies.     

Radioactivity in coffee

This research was dedicated to the study of the background levels of ²¹⁰Po and natural gamma emitters as ⁴⁰K, ²¹⁴Pb, ²¹⁴Bi, ²²⁸Ac, ²¹²Pb and ²¹²Bi in coffee powder and in coffee beverage; also the artificial ¹³⁷Cs was determined. In the coffee powder the mean ²¹⁰Po activity resulted 7.25 ± 2.25 × 10^?2 Bq kg^?1. ⁴⁰K showed a mean activity of 907.4 ± 115.6 Bq kg^?1. The mean activity concentration of ²¹⁴Pb and ²¹⁴Bi, indicators of ²²⁶Ra, given as mean value of the two radionuclides, resulted 10.61 ± 4.02 Bq kg^?1. ²²⁸Ac, ²²⁸Ra indicator, showed a mean activity concentration of 13.73 ± 3.20 Bq kg^?1. The mean activity concentration of ²¹²Pb, ²²⁴Ra indicator, was 8.28 ± 2.88 Bq kg^?1. ²⁰⁸Tl, ²²⁴Ra indicator, presented a mean activity concentration of 11.03 ± 4.34 Bq kg^?1. In all samples, the artifical ¹³⁷Cs resulted below the detection limit (2.0 Bq kg^?1). The arithmetical mean value of percentage of ²¹⁰Po extraction in coffee beverage resulted 20.5 ± 6.9. The percentage of transfer of gamma emitters,⁴⁰K, ²¹⁴Pb, ²¹⁴Bi, ²²⁸Ac, ²¹²Pb, ²⁰⁸Tl resulted of 80.0, 33.5, 24.7, 30.0, 35.1 and 53.5 % for ⁴⁰K, ²¹⁴Pb, ²¹⁴Bi, ²²⁸Ac, ²¹²Pb and ²⁰⁸Tl respectively.     

宝兴大理石矿的放射性检测

宝兴县境内的大理石资源以其白度高、储量丰、品质优、易开采而享誉中外。对四川省宝兴县陇东镇大理石矿区进行了放射性环境地质调查,通过对取回的大理石样品中226Ra、232Th、40K这3种核素的比活度的测定,根据比活度换算出这几种核素的外照射指数和内照射指数,把所得结果和中华人民共和国国家标准《建筑材料放射性核素限量》中规定的建筑性材料分类标准作对比后发现其内照射指数与外照射指数都符合《建筑材料放射性核素限量》中A类建筑材料和装饰材料的要求,它的产销与适用范围不受限制。     

Plutonium and americium in sediment samples along the Romanian sector of the Danube river and the Black Sea coast

The concentrations of²³⁸Pu,^239,240Pu and²⁴¹Am were determined in eight sediment samples, collected from the bed of the Romanian sector of the Danube river and the Black Sea coast during 1994 and 1995. Fusion with potassium carbonate was used to achieve complete dissolution of the samples. Tracers,²⁴²Pu and²⁴³Am, were added and the separation of plutonium from americium, uranium and thorium was performed by anion exchange. Americium was separated from uranium in two steps, using a conventional anion exchange resin and an extraction chromatographic resin for transuranics. After electrodeposition on stainless steel discs the nuclides were counted with -spectrometry with -PIPS detectors. The total plutonium concentrations obtained by this method were compared with the acid leachable plutonium concentrations reported for the same samples in a previous paper.     

Spectroscopic and energetic properties of thorium(IV) molecular clusters with a hexanuclear core

The spectral and energetic properties of three polynuclear thorium(IV) molecular complexes Th(6)(OH)(4)O(4)(H(2)O)(6)(HCOO)(12)·nH(2)O (1), Th(6)(OH)(4)O(4)(H(2)O)(6)(CH(3)COO)(12)·nH(2)O (2), and Th(6)(OH)(4)O(4)(H(2)O)(6)(ClCH(2)COO)(12)·4H(2)O (3) have been studied. Each complex has a hexanuclear core with six 9-coordinate Th(IV) cations bridged by four μ(3)-hydroxo and four μ(3)-oxo groups. The +12 core is stabilized by twelve bridging carboxylate functionalized organic acid (formate, acetate, and chloroacetate) units. The calculated (1)H NMR chemical shifts for the four μ(3)-hydroxo, water, and formate protons are reported and compared to the experimental values. The vibrational frequencies were calculated to aid in the assignment of the observed Raman bands. The Mulliken and NBO (natural bond orbital) charges are calculated for the Th clusters. The Th atoms are positive and the bridging O and O(H) are negative. The analysis of the calculated highest-occupied and lowest-unoccupied molecular orbitals (HOMO and LUMO) is reported. The average water complexation energies, the gas phase, the aqueous and dimethylsulfoxide (DMSO) acidities were predicted, and the Th clusters are found to be mild to strong acids in gas phase yet they behave as weak acids in solution.     

Radioactivity in deuterated compounds

Commercially available D₂O and deuterated toluene have been measured with a liquid scintillation spectrometer and were found to contain 2.71–6.15 Bq of tritium in 1 ml of D₂O, and 1.10 Bq of tritium in 1 ml of deuterated toluene.     

Isotopic compositions of terrestrial thorium: A search in terrestrial thorium for the unidentified excess 4.6 meV alpha-activity of lunar thorium

Since thorium in lunar crystalline rocks was reported to be excessive in 4.6 MeV alpha-activity up to 80%, which was attributed to a long-lived isomer of²³²Th with an origin different from normal thorium, we have measured alpha-spectra of various terrestrial thorium in order to see if terrestrial thorium also contains some excess 4.6 MeV alpha-activity. The results showed that the content of the excess 4.6 MeV alpha-activity in terrestrial thorium, if any, is much less than 3%. An approach to set an upper limit for the excess alpha-activity in terrestrial thorium is proposed. The origin of the excess alpha-activity is discussed.