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1.
Factors that influence the adsorption of trace elements or radionuclides on hydrous iron oxides were investigated. The adsorption of monovalent cations (Cs+, Rb+) on hydrous iron oxides is not strongly pH-dependent and it can be regarded as nonspecific. On the other hand, the adsorption of Ag+, divalent cations (Zn2+, Cd2+, Mn2+, Sr2+) or trivalent cations (Cr3+, La3+, Ce3+, Eu3+, Gd3+, Er3+, Yb3+) is strongly pH-dependent. The regularities of the adsorption of these cations on hydrous iron oxides are discussed. Also, the differences in the adsorption behaviour of some divalent and trivalent cations are explained. Freshly precipitated iron(III) hydroxide can be used for the decontamination of radionuclides from low-level waste solutions. However, the efficacy of decontamination depends on the oxidation state and the chemical properties of radionuclides.  相似文献   

2.
Similar distributions for 238U, 232Th, 226Ra, 210Po, 238,239,240Pu, 137Cs and trace elements were obtained in sediment samples collected along the Romanian sector of the Danube River and the Black Sea coast during 1994. The radionuclide and trace element accumulation in the investigated samples is discussed with respect to their geochemical behavior and the mineralogical structure of the samples. The latter, investigated by X-ray diffraction and cation exchange capacity of the same samples, proves to be an important factor in the selection of sampling sites for monitoring the pollution of river basins and the sea.  相似文献   

3.
New data on the concentrations of the main gamma-emitting radionuclides, minor and trace elements, and isotopes of uranium (with Ra-226 as a daughter product of U-238) and thorium in soils and sediments of the Shu valley (from the river Chon-Kemin to the river Kuragatty downstream the river Shu) are presented, determined by high-resolution gamma-spectrometry, k 0-instrumental neutron activation analysis and alpha-spectrometry with appropriate radiochemical separations of the samples, respectively. The results obtained showed an aquatic migration pathway of most of the trace elements and radionuclides and predicted water pollution downstream the river Shu. The scandium method showed pollution by As, Br, Ca, Cr, Zr of the Tasotkel dam impoundment and by Ca and Cr of the river Shu below its confluence with the river Kuragatty. According to the disequilibrium isotopic method for uranium (using the isotopic ratio U-234/U-238), areas with accumulation and leaching processes were estimated for soils and sediments of the river Shu and its main inflows.  相似文献   

4.
Mitchell  R. L. 《Mikrochimica acta》1951,36(2):1042-1047
Summary The total content of trace elements in rocks, minerals and soils is determined by a semi-quantitativecathode layer arc spectrographic technique. For more accurate determinationsa variable internal standard technique, in which the trace element contents are compared with that of iron, is employed. This method is combined with a chemical concentration for the analysis of extracts of soils and plant materials. The chemical concentration technique involves the use of 8-hydroxyquinoline, tannic acid and thionalide, and gives recovery of microgram quantities of most trace elements, rejecting at the same time the alkalis, alkaline earths and phosphate.
Zusammenfassung Der Gesamtgehalt von Spurenelementen in Gesteinen, Mineralien und Bodenproben wird nach einem halbquantitativen Verfahren bestimmt; hiezu werden die Proben in gehöhlten, als Kathoden geschalteten Elektroden im Bogenstrom verbrannt. Für genauere Bestimmungen wird nach einem abgeänderten Verfahren der quantitativen Spektralanalyse die Menge des Spurenelementes der Probe in Bezug auf ihren Eisengehalt ermittelt. Diese Methode ist mit einer chemischen Anreicherung für die Untersuchung von Bodenextrakten und Pflanzenmaterial kombiniert. Die Technik der chemischen Anreicherung beruht auf der Verwendung von 8-Oxichinolin, Gerbsäure und Thionalid; auf diese Weise lassen sich Mikrogramme der meisten Spurenelemente ermitteln, bei gleichzeitiger Abscheidung der Alkalien, Erdalkalien und Phosphate.

Résumé La teneur globale des traces d'éléments dans les roches, les minéraux et les sols, est déterminée par une technique semi-quantitative, spectrographique d'arc à couche cathodique. Pour les dosages plus précis, on emploie une technique à étalon interne variable dans laquelle les teneurs en traces sont comparées à celles du fer. Cette méthode est combinée avec une concentration chimique pour l'analyse des extraits de sols et de végétaux. La technique de concentration chimique comporte l'emploi d'oxine, d'acide tannique et de thionalide et permet de récupérer des quantités de l'ordre du microgramme de la plupart des éléments en traces, ce qui élimine simultanément les alcalins, les alcalino-terreux et les phosphates.
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5.
Radionuclides undergo redistribution and change existence forms (and, therefore, migration dynamics) not only immediately after they enter into the environment, but also during migration. The latter can be associated with changes in the delivery medium (for example, as strongly contaminated wastewaters is diluted by natural), decrease in the concentration of radionuclides (during their sorption and coprecipitation on soil or host rock microparticles), or change in carrier forms (dissolution of fuel matrices). In view of the multifactor nature and complexity of these processes, we set ourselves the task to summarize results obtained at the GEOKHI RAS on the forms of existence and migration dynamics of radionuclides in radioactively contaminated soils. As objects for study we used soils typical of the forest-steppe zone of the Eastern Ural Radioactive Trace (EURT) and taken at a distance of 2 through 8 km from the Trace axis and 2–4 km from the accident place, as well as samples of the high-water bed soils and sediments of the Enisey River, taken 60 km downstream from the Mining Chemical Combine (MCC).  相似文献   

6.
Summary Mobility of some trace elements in a soil under different conditions of leaching has been measured in terms of RF values with the help of the thin layer method of chromatography. While the iron ions were immobile in a soil of pH 8.8, the mobility of other trace elements was also seriously affected by the presence of Na2CO3. Appreciable changes also occurred in the RF values of the trace elements with the change in the nature and concentration of other leachates. Further the removal of organic matter from the soil resulted in an increase in the movement of the trace elements.
Zusammenfassung Es wurde die Beweglichkeit von Spurenelementen in Böden gemessen und durch die RF-Werte mit Hilfe der Dünnschichtchromatographie charakterisiert. Eisen wird bei einem pH von 8,8 unbeweglich. Auch andere Spurenelemente sind im alkalischen Bereich wenig beweglich. Die Entfernung organischer Komponenten aus dem Boden erhöht die Beweglichkeit.
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7.
Diffusion coefficients of22Na,90Sr and134Cs in some aluminoborosilicate and silicophosphate glasses and ceramics have been determined by the integral residual radioactivity method. The temperature dependence of22Na diffusion coefficients has also been found.  相似文献   

8.
Samples of natural and fertilised soils were collected from Al-Gheran region, west of Tripoli, Libya. The samples were investigated by means of INAA and ED-XRF for Al, Si, K, Ca, Sc, Cr, Mn, Fe, Co, Zn, Br, Rb, Sr, Y, Zr, Nb, Cs, Ba, Hf, Ta, Pb and Th. The results indicate that the concentrations of K, Ca, Zn, Sr and Pb are 2–4 fold higher in fertilised compared to natural soil, while the concentrations of Al, Si, Cr, Mn, Fe, Co, Rb, Y, Nb, Cs, Ba Ta and Th are nearly the same in all samples. Mn and Fe values in two arable soils have been found to be 4–6 times lower than the average concentration in the earth's surface soils. This study concludes that, although the levels of some trace elements important for human health are very low in both natural and fertilised soils. Further research is needed to understand the full significance of the distribution transfer and toxicity of trace elements introduced in imported fertilisers.  相似文献   

9.
Toenail samples were collected from 129 carpenters (average age 47). The bone and blood lead data for these carpenters have shown a broad range of lead-level exposure in this population. A total of 28 elements were measured in the sample set by a combination of instrumental neutron activation analysis (INAA) and graphite furnace atomic absorption spectrometry (GFAAS) methods. Of the elements measured, only Co, Cr, Fe, Na, Cd, Cu, F, and Ni were significantly correlated with lead. A statistical treatment of the overall data set, including principal component analysis, was further applied in an attempt to correlate the elements in the samples.  相似文献   

10.
Rice grain samples and surface paddy soil samples were collected from 20 sites throughout Aomori Prefecture, Japan, and the concentrations of 25 elements in the polished rice and 33 elements in the soils were determined by neutron activation analysis, inductively coupled plasma-mass spectrometer or atomic adsorption spectrometer. The range of essential element concentrations in the polished rice was within one order of magnitude, however, the range for most of the trace elements was more than one order of magnitude. The range of element concentrations, except for I, in the paddy soils was within one order of magnitude. The ±95% confidence intervals of the soil-to-polished rice transfer factors for all elements, except for Pb, were within two orders of magnitude, and the geometric mean values were as follows: Cl, Mo and Zn (0.1–1); K, Cu, Cd, Rb, Mg, Mn, and Ag (0.01–0.1); Ni, As, Ca, Se and I (0.001–0.01); Na, Cs, Sr, Co, Cr, V, Ba, Pb, Fe and Al (<0.001).  相似文献   

11.
Chemical speciation of radionuclides through the microbial process in soils   总被引:1,自引:0,他引:1  
Environmental factors (nutrients and pH) influence the retention of Sr, Cs, and Ba as analogue of long-lived radionuclides by the microorganism. The effect of pH and concentration of organic nutrients are proved to be significant factors for retention of cations (Sr, Cs and Ba) by the microorganisms inoculated from surface soil. Microorganisms can affect the speciation of Sr, Cs, and Ba in the environment. Concentration of organic nutrients and pH are indicated to be the important environmental factors in the consideration of the migration of the radionuclides through microbial processes in the terrestrial environment.  相似文献   

12.
Removal of the native surface oxide from steel is an important initial step during vacuum brazing. Trace and alloying elements in steel, such as Mn, Si, and Ni, can diffuse to the surface and influence the deoxidation process. The detailed surface chemical composition and grain morphology of the common stainless-steel grade 316L is imaged and spectroscopically analyzed at several stages of in-vacuum annealing from room temperature up to 850°C. Measurements are performed using synchrotron-based X-ray photoemission and low-energy electron microscopy (XPEEM/LEEM). The initial native Cr surface oxide is amorphous and unaffected by the underlying Fe grain morphology. After annealing to ~700°C, the grain morphology is seen at the surface, persisting also after the complete oxygen removal at 850°C. The surface concentration of first Mn and then Si increases significantly when annealing to 500°C and 700°C, respectively, while Ni and Cr concentrations do not change. Mn and Si are not located only in grain boundaries or clusters but are distributed across over the surface. Both Mn and Si appear as oxides, while Cr oxide becomes metallic Cr. Annealing from 500°C up to 850°C leads to the removal of first the Mn and then Si oxides from the surface, while Cr and Fe are completely reduced to metals. Deoxidation of Cr occurs faster at the grain boundaries, and the final Cr metal surface content varies between the grains. The findings are summarized in a general qualitative model, relevant for austenite steels.  相似文献   

13.
建立了微波消解-电感耦舍等离子体质谱(ICP.MS)法同时测定原油及自然风化后原油中的V、Cr、Mn、Fe、Ni、zn、Mo、Ba等11种微量金属元素的方法.结果表明,11种微量金属元素的检出限为0.0056~0.8729μg/g,线性关系良好,相关系数r≥0.9995;相对标准偏差(RSD)<5.0%.经过30d风化...  相似文献   

14.
This work is part of a project with the IAEA, in a coordinated program on Trace Elements in Human and Bio-Environmental Systems to evaluate their nutritional requirements, interrelations and the role of trace elements in health, metabolism, etc. Cow's milk being regarded as one of the most important and nutritious foodstuffs consumed by people. Hence as a first step, an elemental analysis for milk was carried out for this purpose; a few samples of pasteurized milk and local sample were investigated for essential and toxic trace elements. The secondary aim of this project was the assessment of various analytical techniques involved. However, in the present work, the methods involved were AAS, PIXE and NAA. The latter method was applied both instrumentally and radiochemically. Although the results pertaining to the various methods employed are not in good agreement. there is, however, some justification to clarify this internal inconsistency. The precision of NAA and AAS allows a greater degree of acceptance. Although PIXE is very fast and rather routine, the technique for trace element analysis needs certain adaptations and development.  相似文献   

15.
Joint leaching of iron and other macro- and microelements including radionuclides from radioactively contaminated floodplain soil of the Yenisei River is studied on miniecosystems. In developing anaerobic conditions, the redox potential Eh decreased to +140 mV, causing partial reduction of iron and solubilisation of iron hydrous oxide and organomineral films of the soil. Leaching of stable elements and radionuclides with water proceeds parallel to that of iron. To accelerate reductive mobilization of iron, 0.4% aqueous ascorbic acid was used instead of water as the leaching liquid phase. In this case, Eh approached –60 mV, and the leaching of stable and radioactive elements considerably increased, the effect being most pronounced for plutonium. To cite this article: E.K. Legin et al., C. R. Chimie 7 (2004).

Résumé

Effet du passage en milieu anaérobie sur la mobilisation des radionucléides dans les sols humides. La lixiviation simultanée du fer et d’autres éléments de sols contaminés de la vallée de la rivière Yénései a été étudiée. En imposant des conditions anaérobies, le potentiel redox chute à 140 mV, causant une réduction partielle du fer trivalent et la solubilisation de l’hydroxyde de fer et du film organominéral du sol. Les lixiviations du fer, des autres éléments et, par conséquent, des radionucléides contaminant le sol vont de pair. Pour accélérer la mobilisation réductive du fer, une solution d’acide ascorbique à 0,4% a été utilisée à la place de l’eau. Dans ces conditions, la valeur de Eh approche –60 mV et la lixiviation des éléments augmente considérablement, cet effet étant plus prononcé pour le plutonium. Pour citer cet article : E.K. Legin et al., C. R. Chimie 7 (2004).  相似文献   

16.
Summary Cubat?o River is located in Santos Basin, S?o Paulo State, Brazil. This region is characterized by the occurrence of estuaries and mangrove. Due to its location, near the coastal line, it is also an important industrial area, where phosphate fertilizer plants, petrol refineries, and chemical and steel industries are present. Such human activities contribute to the enhancement of elemental composition in sediments and, in some cases, also increase the radionuclide concentrations, the so called Technologically Enhanced Natural Occurring Radioactive Materials (TENORM). The contamination of land and sediments by TENORM is of major concern. The activity concentration of U and Th series radionuclides was determined in five sediment samples from Cubat?o River. The activity concentration ratio was also determined. Equilibrium was observed for the ratio 234U/238U. The activity ratios of Th/238U, 228Ra/226Ra and 210Pb/226Ra were higher than the unity. In the first two cases, the observed values are due to the higher activity of Th in the sediment and in the last case are probably due to the atmospheric deposition of 210Pb.  相似文献   

17.
Leaf and aerosol samples were monthly collected in Mt. Sefuri (Fukuoka Prefecture). Radioactivities of 7Be, 210Pb and 40K were determined with gamma-ray spectrometry. The concentrations of some elements in the leaf samples were determined by neutron activation analysis. Similar seasonal variation of 7Be and 210Pb was observed between leaf and aerosol samples, high in spring and winter and low in summer. Correlation factors for trace elements contained in the leaf show large variations. This indicates that the contribution of two sources (atmospheric deposition and uptake from soil) is very variable.  相似文献   

18.
目的 探究金银花茶样品中8种微量元素的溶出特性。方法 基于电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS),测定样品中Na、Ca、Mg、Mn、Fe、Zn、Cu、Se 8种微量元素含量,并分别研究了浸泡时间、浸泡次数及浸泡温度与元素溶出特性之间的关系。结果 结果表明,金银花茶中微量元素含量丰富,8种元素含量由高到低的顺序为:Ca>Mg> Fe>Na>Mn> Zn>Cu>Se。各元素溶出量随浸泡时间延长而升高,其中Fe溶出率最低,表明Fe最难溶出。除Na和Se以外,各元素溶出量随浸泡次数增加而降低,随浸泡温度升高而升高;Na的溶出量随浸泡次数增加呈先降低后升高的趋势,而Se的溶出量随浸泡次数增加而降低;Na和Se的溶出量均随浸泡温度升高呈先升高再降低的趋势。各元素溶出量与浸泡时间、浸泡次数及浸泡温度之间的关系均可通过建立不同类型的数学模型进行描述。结论 从保健茶饮的功能性和风味角度考虑,金银花茶冲泡应选用100℃的水温,且冲泡次数应不超过4次。  相似文献   

19.
Global status of trace elements in the ocean   总被引:2,自引:0,他引:2  
Trace elements in seawater can be limiting factors of biological productivity, tracers of ocean circulation and biogeochemical processes, and proxies for paleoceanography. The global status of trace elements and their isotopes (TEIs) in the ocean is being explored this decade through an international study of the global marine biogeochemical cycles of TEIs (GEOTRACES). Such an international study has become possible due to recent methodological developments in sampling, preconcentration, and measurement of TEIs. Here, we present an overview of recent methodological developments and initial GEOTRACES intercalibration activities for obtaining data about TEIs that are accurate, precise, and intercomparable.  相似文献   

20.
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