共查询到20条相似文献,搜索用时 31 毫秒
1.
Christine Wallace Jeremy J. Bellucci Antonio Simonetti Tim Hainley Elizabeth C. Koeman Peter C. Burns 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):993-1003
The spatial distribution of radiation within trinitite thin sections have been mapped using alpha track radiography and beta autoradiography in combination with optical microscopy and scanning electron microscopy. Alpha and beta maps have identified areas of higher activity, and these are concentrated predominantly within the surficial glassy component of trinitite. Laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses conducted at high spatial resolution yield weighted average 235U/238U and 240Pu/239Pu ratios of 0.00718 ± 0.00018 (2σ) and 0.0208 ± 0.0012 (2σ), respectively, and also reveal the presence of some fission (137Cs) and activation products (152,154Eu). The LA-ICP-MS results indicate positive correlations between Pu ion signal intensities and abundances of Fe, Ca, U and 137Cs. These trends suggest that Pu in trinitite is associated with remnants of certain chemical components from the device and surrounding Trinity test-related structures at ground zero. In contrast, negative correlations between Pu ion signals and SiO2 and K2O contents were observed within the glassy matrix of trinitite. This LA-ICP-MS result was corroborated by combined back-scattered electron imaging and alpha radiography, and indicates that Pu was not incorporated into unmelted crystalline grains of precursor minerals (i.e., quartz-SiO2 and K-feldspar-KAlSi3O8) present within the desert sand at the Trinity site. The results from this study indicate that the device-related radionuclides were preferentially incorporated into the glassy matrix in trinitite. 相似文献
2.
Distribution and behavior of some radionuclides associated with the Trinity nuclear test 总被引:1,自引:0,他引:1
Jeremy J. Bellucci Christine Wallace Elizabeth C. Koeman Antonio Simonetti Peter C. Burns Jeremy Kieser Eli Port Terri Walczak 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2049-2057
The activities of 133Ba, 137Cs, 152Eu, 154Eu, 155Eu, 239Pu, and 241Am were determined by gamma spectroscopy on the largest sample set (n = 49) of bulk trinitite to date. The range in activity for all isotopes is large. For example, the activity of 241Am (normalized to the time of detonation) ranges between 1 and 42 Bq/g. Comparison of activities for isotopes derived from the device, 241Am versus 137Cs, 155Eu, and 239Pu, indicate positive trends. Correlations were not observed between the activities of the soil-derived activation products 152Eu and 154Eu and the radioisotopes from the device. The calculated ratio of fission products (155Eu/137Cs) is 0.012 ± .006 (1σ, n = 3), which is lower than predicted for the thermal neutron-induced fission of 239Pu (~0.03). This discrepancy may be attributed to the spontaneous fission of the natural U tamper resulting in mixing between fission products from 239Pu and 235U. The spatial distribution of the trinitite samples relative to ground zero has been modeled based on the activity of 152Eu. The calculated distances do not correlate with any of the activities for the radioisotopes investigated here, and suggest a relatively homogeneous distribution. However, trinitite samples with the highest activities for 137Cs, 239Pu, and 241Am yield the shortest calculated distances of 50–60 m away from ground zero. 相似文献
3.
Wenting Bu Qiuju Guo Jian Zheng Shigeo Uchida 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(2):999-1005
Surface soil samples collected in the Jiuquan region in the downwind area of the Chinese nuclear test site (CNTs) were analyzed for Pu isotopes. The 239+240Pu activities ranged from 0.025 ± 0.009 to 0.89 ± 0.16 mBq g?1, varying significantly with different sampling sites. The Dunhuang city that is located in the southwestern part of the Jiuquan region received the heaviest Pu deposition (239+240Pu activities, 0.23–0.89 mBq g?1). Most of the 240Pu/239Pu isotopic ratios were similar with that of the global fallout. However, the low values (0.080–0.147) observed in three sampling sites further supported the finding of Pu originated from CNTs in that region. 相似文献
4.
Beata Skrzypiec Paweł Jodłowski Jerzy W. Mietelski 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):771-775
Paper presents results of the plutonium deposition measurements in Gorce Mountains—a small part of western Polish Carpathians, Southern Poland where a national park was established in 1981. Samples were collected in both forest and alp areas. They were analyzed by means of alpha spectrometry preceded by radiochemical treatment. The results for activity concentration are then used to calculate cumulated deposition which range from 45.7 ± 4.3 to 164 ± 19 Bq/m2, what means that it reach in maximum almost three times higher value than UNSCEAR average for global fallout, expected for our latitude. The isotopic activity ratio 238Pu to 239+240Pu indicates global fallout as the main if not the only source of Pu. Nevertheless, presented results for plutonium reveal more uniform Pu deposition pattern in Gorce Mountains than it was observed for 137Cs in earlier study using the same samples. 相似文献
5.
Zhiyong Liu Jian Zheng Masatoshi Yamada Shaoming Pan Hodaka Kawahata 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):911-917
Sediment core samples were collected from Hiroshima Bay in the Seto Inland Sea, western Northwest Pacific Ocean, and their 239+240Pu activities and 240Pu/239Pu atom ratios were determined by sector field ICP-MS. The activities of 239+240Pu ranged from 0.556 ± 0.025 to 0.745 ± 0.023 mBq/g. The atom ratios of 240Pu/239Pu were almost constant within the whole depth; the average value was 0.227 ± 0.014. This atom ratio was significantly higher than the mean global fallout ratio of 0.18, proving the presence of close-in fallout Pu that originated from the Pacific Proving Ground (PPG). The water masses exchanges between the Kuroshio Current and the Seto Inland Sea brought the PPG source Pu to this area, then Pu was extensively scavenged into sediment particles supplied by the rivers around the bay. The relative contributions of the global fallout Pu and the PPG close-in fallout Pu were evaluated by the two end-member mixing model. The contribution of the PPG close-in fallout was 38?C41% of the total Pu in sediment. The remaining 59?C62% was attributed to direct global fallout and the land-origin Pu transported by the rivers around the Hiroshima Bay. 相似文献
6.
J. W. Mietelski B. Kubica P. Gaca E. Tomankiewicz S. Błażej M. Tuteja-Krysa M. Stobiński 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(3):523-533
Activity concentrations and inventory for 238Pu, 239+240Pu, 241Am, 90Sr, and 137Cs in soil from Tatra Mountains of Poland are presented. Soil samples were collected using 10 cm diameter cores down to 10
cm and sliced into 3 slices. Details of the applied procedure are described with the quality assurance program. The maximum
activity concentrations found for various samples were: 1782±13 Bq/kg, 17.4±0.9 Bq/kg, 3.4±0.3 Bq/kg and 84±7 Bq/kg for 137Cs, 239+240Pu, 241Am and 90Sr, respectively. The maximum cumulated deposition of 239+240Pu is 201±8 Bq/m2. The origin of radionuclides is discussed, based mostly on the observed isotopic ratio of Pu. Significant correlations were
found between 239+240Pu, 241Am and 137Cs. The effective vertical migration rate seems to be in the order of: 90Sr≫Pu>Am>Cs. 相似文献
7.
Héctor Hernández-Mendoza Abel Yllera 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1417-1420
Two extraction processes of plutonium (Pu) on planchets from alpha spectrometry (AS) have been evaluated by inductively coupled plasma sector field mass spectrometry with a desolvator system (Aridus–ICP–SFMS). The samples were traced with known concentrations of 239Pu (1.2 × 103 fg) and 242Pu (2 × 103 fg) followed by an electrodeposition in planchets, according to the Hallstadius method. The processes of extraction were carried out with 50 mL of 0.36 mol L?1 HNO3 every 30 min up to 180 min in a glass beaker at 60 °C. The first process was on a hotplate and the second used an ultrasonic system. Finally, samples were evaporated to dryness, and resuspended in 10 mL of 0.72 mol L?1 HNO3 for evaluation. The results showed that at 120 min, a ~70 % recovery of 239Pu and a ~80 % recovery of 242Pu in both processes were obtained. The average recoveries of 239Pu and 242Pu at 180 min using the hotplate in plate were 93.4 ± 4.6 and 93.7 ± 4.2 % respectively, and with the ultrasonic system were 96.0 ± 4.3 and 98.2 ± 1.0 % respectively. In conclusion, both processes are suitable for Pu extraction, and Aridus–ICP–SFMS is an essential technique for the reassessments and quantification of Pu. In addition, procedural blanks spiked with 1 × 102 fg mL?1 U were prepared for each process, in order to study the contribution of the 238U on the background signal at m/z = 239, which was 0.5 ± 0.2 cps, indicating that the contribution of 238U on the 239Pu signal was negligible. Furthermore, this methodology can be applied to sample planchets with environmental, food, biological and nuclear origin, and thereby to avoid repetitive analysis when Pu concentration determined by AS are under minimum detectable activities. 相似文献
8.
Preseparation of lanthanoids by substoichiometric precipitation of calcium oxalate and simple radiochemical separation of lanthanoids by lanthanum oxalate have been developed. They were combined with neutron activation analysis of a marine macro-alga (Laminaria religiosa, brown alga) sample. Quantitative recovery of lanthanoids throughout the procedure was examined by radiotracer technique. Eleven lanthanoids, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Er, Yb and Lu, at 0.7–140 ng g–1 were determined with a relative standard deviation of 1–7% (n=3). Concentrations of lanthanoids in the marine macro-alga were compared with land plant and sea water. 相似文献
9.
The compositional zoning of the garnet in a strongly deformed eclogite from Raobazhai foliated peridotite has been recognized. The CaO concentrations of the garnet are decreased from the core to the rim, while its MnO concentrations are increased, suggesting the retrograde origin of such CaO—MnO zoning. The tie line of garnet + omphacite from this eclogite gives a Sm-Nd age of (187 ± 5) Ma, which is less significant than the Sm-Nd ages of (221±5)—(228 ± 3) Ma and (210 ± 6)—(214 ± 6) Ma for ultrahigh-pressure eclogites in the southern Dabie zone and in the northern Dabie zone, respectively. This younger Sm-Nd age could result from the143Nd/144 Nd ratio decrease of the retrograde zone in the garnet. The δ18O values of the garnet and omphacite show that their fractionation values are less than the equilibrium fractionation value between the garnet and omphacite at 500—900°C, which suggests an oxygen isotopic disequilibrium between them. 相似文献
10.
《Analytical letters》2012,45(1):142-150
We present a precise and accurate method for the determination of 143Nd/144Nd isotope ratio without Nd and Sm separation by multiple collector inductively coupled plasma mass spectrometry. We corrected instrumental mass discrimination by applying the natural constant 146Nd/144Nd ratio as an internal standard after isobaric interference correction of 144Sm on 144Nd using interference-free 147Sm/149Sm ratio for Sm mass fractionation. The present method was validated by duplicate analyses of several certified reference materials after dissolution and cation-exchange resin purification. The precision (2σ) of the 143Nd/144Nd ratio is less than 10 ppm (internal) and 20 ppm (external), respectively. 相似文献
11.
A chromatographic separation technique for 142Nd/144Nd and 143Nd/144Nd isotope ratio measurements is established and applied to the analyses of geological standards of basaltic compositions (BCR-2, BIR-1) using Isoprobe-T TIMS. The instrument was tested for reliability and reproducibility to measure Nd isotope composition using the synthetic standard JNdi-1. The techniques were also applied to a carbonatite lava sample, OL-6, Oldoinyo Lengai, to check the validity of method for carbonatite matrix. The isotope ratios of 143Nd/144Nd for synthetic Nd standard JNdi-1, geological standards BCR-2, BIR-1, and carbonatite lava sample OL-6 obtained by these methods are in good agreement with previously published data. The 143Nd/144Nd values for JNdi-1 and BCR-2 have an external precision of ±13 ppm and ±15 ppm (2σ), respectively. The JNdi-1 and BCR-2 data for 142Nd/144Nd has an external precision of ±12 ppm and ±8 ppm (2σ), respectively. The 142Nd/144Nd composition of the two geological standards BCR-2 and BIR-1 are indistinguishable from synthetic mono-element standard JNdi-1, and they all fall within the 12 ppm (2σ) envelope of external precision. The external reproducibility is sufficient to distinguish and resolve 20 ppm anomalies in 142Nd/144Nd values. 相似文献
12.
Kevin B. Lavelle Samuel Glover William B. Connick Henry Spitz 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(3):677-683
This paper summarizes a new method for preconcentration of rusty metal samples using DIPEX® Actinide Resin from Eichrom Technologies prior to analysis for trace environmental actinides. This method allows for preconcentration of actinides for which the existing lanthanum coprecipitation method is ill-suited. The new and existing methods were shown to provide comparable results for plutonium analysis. Performance was compared for both lab-prepared controls and environmental samples. Using actinide resin, a mean 238Pu activity of 46 ± 13 % mBq (2σ) was measured, while 238Pu activity of 40 ± 6 % mBq (2σ) was measured using lanthanum coprecipitation. Small quantities of 239+240Pu, likely attributable to fallout, were also detected. 相似文献
13.
Gabriele Tamborini Maria Wallenius Olivier Bildstein Leena Pajo Maria Betti 《Mikrochimica acta》2002,139(1-4):185-188
Methodologies based on secondary ion mass spectrometry (SIMS) for isotopic measurements in nuclear forensic applications
relevant to the age determination of Pu particles and isotopic composition of oxygen for geolocation assignment are described.
For the age determination of Pu particles, a relative sensitivity factor (RSF) to correct for the different ionisation efficiencies
of U and Pu, was obtained by analysing standard Pu materials with known ages. An RSF of 2.41±0.05 was obtained for PuO2 from measurements on samples with different Pu/U ratios. In a sample of known origin, using this RSF value, the age calculated
from the 238Pu/234U and 240Pu/236U ratios agreed well with the reported age of 2.3 years. For geolocation assignment, a new approach based on the measurement
of differences in the natural abundance of 18O and 16O isotopes and their ratio was developed. The instrumental mass discrimination of the 18O/16O ratio was determined using three O-isotope samples of different chemical composition. The measured precision (the standard
error of 100 cycles/analysis) obtained for the oxygen isotopic measurement on the samples was typically ±1.1‰. 相似文献
14.
Brent S. Matteson Warren J. Oldham Jr. 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):781-785
The 2011 Las Conchas fire burned 632 km2 of ponderosa pine forests and piñon–juniper woodlands in the Jemez Mountains in north central New Mexico. In the weeks following the fire, heavy rainfall caused extensive flooding and erosion of surface soil and ash from the affected areas. Samples from mud and ash flows were collected and analyzed for 137Cs and Pu, which were originally deposited as global fallout during the era of atmospheric nuclear testing. The mean concentrations for 238Pu, 239,240Pu and 137Cs were 0.18 ± 0.05, 4.16 ± 1.95, and 111 ± 56 mBq/g, respectively. 239,240Pu and 137Cs are significantly elevated above non-fire affected regional background levels. 相似文献
15.
J. Aign B. Wierczinski A. Türler 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(1):37-42
Due to the different 240Pu/239Pu atom ratios from different sources of Pu in the environment, Pu isotopes have been widely used for source identification
of radionuclides in sediments. In this work, using sector-field ICP-MS, we investigated Pu inventory and its isotopic composition
in a lacustrine sediment core collected in Chenghai Lake, SW China. The 240Pu/239Pu atom ratios in this sediment core ranged from 0.166 to 0.271 with a mean of 0.195±0.021, which was slightly higher than
that of global fallout. The 239+240Pu/137Cs activity ratios ranged from 0.0155 to 0.0411, with a mean of 0.0215, and the 239+240Pu inventory was 35.4 MBq/km2; both 239+240Pu/137Cs activity ratio and Pu inventory were close to those values of global fallout at 20–30 °N. Three peaks were observed for
both 137Cs and 239+240Pu activities in the examined sediment core; they most probably indicated the maximum deposition of global fallout between
1963 and 1964, the fallout from a series of Chinese nuclear tests during the 1970s, and the deposition of resuspended Pu-bearing
particles from the Chernobyl accident. Therefore, the vertical profile of Pu isotopes should provide useful time markers for
rapid dating of recent sediments.
These authors contributed equally to this work. 相似文献
16.
N. Erdmann J.-V. Kratz N. Trautmann G. Passler 《Analytical and bioanalytical chemistry》2009,395(6):1911-1918
Micro-particles containing actinides are of interest for risk assessments of contaminated areas, nuclear forensic analyses,
and IAEA as well as Euratom safeguards programs. For their analysis, secondary ion mass spectrometry (SIMS) has been established
as the state-of-the-art standard technique. In the case of actinide mixtures within the particles, however, SIMS suffers from
isobaric interferences (e.g., 238U/238Pu, 241Am/241Pu). This can be eliminated by applying resonance ionization mass spectrometry which is based on stepwise resonant excitation
and ionization of atoms with laser light, followed by mass spectrometric detection of the produced ions, combining high elemental
selectivity with the analysis of isotopic compositions. This paper describes the instrumental modifications for coupling a
commercial time-of-flight (TOF)-SIMS apparatus with three-step resonant post-ionization of the sputtered neutrals using a
high-repetition-rate (kHz) Nd:YAG laser pumped tunable titanium:sapphire laser system. Spatially resolved ion images obtained
from actinide-containing particles in TOF-SIMS mode demonstrate the capability for isotopic and spatial resolution. Results
from three-step resonant post-ionization of bulk Gd and Pu samples successfully demonstrate the high elemental selectivity
of this process. 相似文献
17.
Re-examination of all known xenon isotopic data for ordinary chondrites reveals that244Pu fission xenon can be resolved in about one-fourth of the meteorites of this class. The amounts of244Pu fission xenon found in these meteorites range from ca. 1–2 up to 6–8·10?12 ccSTP/g. These meteorites started to retain their xenon some 200–500 million years later than did the carbonaceous chondrites Allende, Groznaya, Mokoia, Murchison, Murray, and Renazzo which began to retain their xenon over 4800 million years ago. 相似文献
18.
A Peltier-cooled silicon drift detector was successfully applied for conversion electron spectrometry. The energy resolution of the detector for 45 keV electrons was 0.50 keV (FWHM). The approximate thickness of the dead layer was determined to be 140 ± 20 nm Si equivalent. The relative efficiency of the detector was verified to be approximately constant in the energy range of 17–75 keV. This is concordant with the high transparency of the thin dead layer and the sufficient thickness of the detector (450 μm) to stop the electrons. The detector is suitable for use in plutonium analysis of chemically prepared samples. Moreover, it was demonstrated that conversion electron spectrometry is better than alpha spectrometry in preserving its capability to determine the 240Pu/239Pu isotopic ratio as a function of sample thickness. The investigated measurement technique can be considered a promising new tool in safeguards, complementary to existing methods. 相似文献
19.
Jiayu Yang Xinjie Hu Huaiyuan Zhang Haiqin Chen M’balu. R. Kargbo Jianxin Zhao Yuanda Song Yong Q. Chen Hao Zhang Wei Chen 《Applied biochemistry and biotechnology》2014,173(7):1849-1857
Malic enzymes are a class of oxidative decarboxylases that catalyze the oxidative decarboxylation of malate to pyruvate and carbon dioxide, with concomitant reduction of NAD(P)+ to NAD(P)H. The NADP+-dependent malic enzyme in oleaginous fungi plays a key role in fatty acid biosynthesis. In this study, the malic enzyme-encoding complementary DNA (cDNA) (malE1) from the oleaginous fungus Mortierella alpina was cloned and expressed in Escherichia coli BL21 (DE3). The recombinant protein (MaME) was purified using Ni-NTA affinity chromatography. The purified enzyme used NADP+ as the cofactor. The K m values for l-malate and NADP+ were 2.19?±?0.01 and 0.38?±?0.02 mM, respectively, while the V max values were 147?±?2 and 302?±?14 U/mg, respectively, at the optimal condition of pH 7.5 and 33 °C. MaME is active in the presence of Mn2+, Mg2+, Co2+, Ni2+, and low concentrations of Zn2+ rather than Ca2+, Cu2+, or high concentrations of Zn2+. Oxaloacetic acid and glyoxylate inhibited the MaME activity by competing with malate, and their K i values were 0.08 and 0.6 mM, respectively. 相似文献
20.
K. Norisuye K. Okamura Y. Sohrin H. Hasegawa T. Nakanishi 《Journal of Radioanalytical and Nuclear Chemistry》2005,267(1):183-193
Summary The present paper describes a new analytical method for determining the 240Pu/239Pu isotopic ratio and 238Pu/239+240Pu α -activity ratio in seawater, both of which are important parameters for determining Pu sources in the ocean. Plutonium
isotopes were preconcentrated from a large volume of seawater (4700-10800 liter) by solid phase extraction using MnO2-impregnated fibers and eluted into 3M HCl. After the elution, the Pu species of all oxidation states were converted to Pu(IV)
using NaNO2, purified by solvent extraction using thenoyltrifluoroacetone (TTA)-benzene, and concentrated in 5 ml of 0.2M HNO2. The 240Pu/239Pu and 238Pu/239+240Pu ratios in the 5-ml final solution were determined by inductively coupled plasma-mass spectrometry (ICP-MS) and α-spectrometry,
respectively. A pg level of Pu, which was a sufficiently large amount for the determination, was obtained by the solid phase
extraction. Through the redox conversion and solvent extraction, the Pu species, such as Pu(III), Pu(IV) and Pu(VI), were
collected at a high recovery of 96±2% (n=3) despite the presence of large amounts of Mn, and interfering 238U (3.3 μg. l-1in seawater) was effectively removed with a decontamination factor of 1.7·107. The accuracy of the method for the 240Pu/239Pu ratio was verified using reference materials of seawater and a terrestrial soil sample. The present technique was applied
to the determination of the 240Pu/239Pu and 238Pu/239+240Pu ratios in coastal and oceanic water. 相似文献