Petrogenesis of lacustrine dolostone is closely related with paleo-lake water conditions.Here we report the high spatial-resolution petrographic and geochemical results of a lacustrine dolomite nodule from the Qingsha...Petrogenesis of lacustrine dolostone is closely related with paleo-lake water conditions.Here we report the high spatial-resolution petrographic and geochemical results of a lacustrine dolomite nodule from the Qingshankou Formation,the Songliao Basin.Sedimentary and elemental signatures confirm the protogenetic origin of this nodule and its effectiveness in recording geochemical characteristics of paleo-lake water during dolomitization.The low Y/Ho ratios,middle rare earth element(MREE)enrichment and subtle positive Eu anomalies within the nodule indicate a fresh water source.However,the Sr isotope values in the core of the nodule(0.7076-0.7080)are close to contemporaneous seawater(0.7074),yet different from the modern river(0.7120)and the host black shale(0.7100).On the premise of excluding the influence of hydrothermal fluids,the significantly low strontium isotope values of the lacustrine dolomite might be caused by seawater interference during dolomitization.Our findings demonstrate that lacustrine dolomite within black shales is not only a faithful tracer of diagenetic water environment,but also a novel and easily identified mineralogical evidence for episodic seawater intrusion event(91 Ma)in the Songliao Basin,which supplements other paleontological and geochemical evidence.展开更多
The present work assesses the temporal distribution pattern and geochemical changes of rare earth elements and Yttrium, Scandium, Thorium, and Uranium delivery into the Oualidia lagoon. Two sediment cores were retriev...The present work assesses the temporal distribution pattern and geochemical changes of rare earth elements and Yttrium, Scandium, Thorium, and Uranium delivery into the Oualidia lagoon. Two sediment cores were retrieved from the Oualidia lagoon and analyzed using neutron activation analysis. The results indicated that heavy rare earth elements are slightly enriched the sediment cores over light rare earth elements. The highest values of REEs were recorded in the top layers of the cores and depleted with depth, suggesting a possible change in factors controlling their accumulation, including mechanical, chemical, and environmental parameters such as weathering intensity, grain size, and Fe-Mn oxides. The sediments display positive Ce anomalies, which are probably related to the submarine weathering process and detrital input. Noting also the variation of hydrodynamics conditions and confinement of the upstream part of the lagoon played a key role in changing the sediment origins.Thus, further investigation of REEs origin in the Oualidia lagoon sediment is required to identify their sources,provenances, and the factors controlling their spatial and vertical distributions. However, these results provide baseline data of occurring changes in REEs geochemical composition and constitute a typical study case to understand the link between sedimentary and geochemistry processes in a lagoonal ecosystem.展开更多
The present work investigates the influences of microalloying with rare earths on the mechanical properties of magnesium alloys.The amount of each rare earth element is controlled below 0.4 wt.%in order not to increas...The present work investigates the influences of microalloying with rare earths on the mechanical properties of magnesium alloys.The amount of each rare earth element is controlled below 0.4 wt.%in order not to increase the cost of alloy largely.The synergic effects from the multi-microalloying with rare earths on the mechanical properties are explored.The obtained results show that the as-cast magnesium alloys multi-microalloying with rare earths possesses a quite high ductility with a tensile strain up to 25-30%at room temperature.Moreover,these alloys exhibit much better corrosion resistance than AZ31 alloy.The preliminary in situ neutron diffractions on the deformation of these alloys indicate that the multi-microalloying with rare earths seems to be beneficial for the activation of more slip systems.The deformation becomes more homogeneous and the resultant textures after deformation are weakened.展开更多
The rare earth elements and yttrium(REY)of the K2 coal from the Moxinpo mine,Chongqing,were determined using inductively coupled plasma mass spectrometry(ICP-MS).The results show that REY are enriched in the K2 coal,w...The rare earth elements and yttrium(REY)of the K2 coal from the Moxinpo mine,Chongqing,were determined using inductively coupled plasma mass spectrometry(ICP-MS).The results show that REY are enriched in the K2 coal,with the average content up to 462 lg/g,much higher than average values of most coals in the world.The REY distribution patterns indicate that the light REY is enriched and show a well-pronounced Eu minimum.The fractionation of individual light-REY is higher than that of the heavy-REY.The REY distribution through the K2 coal seam shows that the top and bottom portion of the coal seam have a lower content of REY than the middle portion.Goyazite and rhabdophane were identified with a scanning electron microscope equipped with an energy-dispersed X-ray spectrometer(SEM-EDX).The REY distributions through the coal seam,SEM-EDX data and the correlation analysis between ash yields and the concentrations have revealed that the REY mainly occurs in the organic matter.The K2 coal is a potential rare-metal resource due to its high REY contents,and the coal ash could be regarded as a new and promising raw material for recovery of REY as a by-product.展开更多
With the increasing demand of rare earth metals in functional materials,recovery of rare earth elements(REEs)from secondary resources has become important for the green economy transition.Molten salt electrolysis has ...With the increasing demand of rare earth metals in functional materials,recovery of rare earth elements(REEs)from secondary resources has become important for the green economy transition.Molten salt electrolysis has the advantages of low water consumption and low hazardous waste during REE recovery.This review systematically summarizes the separation and electroextraction of REEs on various reactive electrodes in different molten salts.It also highlights the relationship between the formed alloy phases and electrodeposition parameters,including applied potential,current,and ion concentration.Moreover,the feasibility of using LiF–NaF–KF electrolyte to recover REEs is evaluated through thermodynamic analysis.Problems related to REE separation/recovery the choice of electrolyte are discussed in detail to realize the low-energy and high current efficiency of practical applications.展开更多
Fluorite mineralization occurs along fractures and cracks of Middle Eocene and Pliocene limestones and marls in the north and northeast of the P?hrenk region (?i?ekdagi, Kirsehir). Tb/Ca ( Tb/La and Y/Ho ratios were o...Fluorite mineralization occurs along fractures and cracks of Middle Eocene and Pliocene limestones and marls in the north and northeast of the P?hrenk region (?i?ekdagi, Kirsehir). Tb/Ca ( Tb/La and Y/Ho ratios were obtained from REE contents of fluorites which have revealed that mineralization is of hydrothermal type. Negative Ce anomalies and positive Eu anomalies reflect that hydrothermal solutions once had high oxygen fugacity. Fluid inclusion studies indicate that homogenization temperatures of mineralization varied between 90oC and 200oC, and hydrothermal solutions are composed of NaCl + KCl + MgCl2 + H2O. In addition, salinity measurements show that hydrothermal solutions were mixed with meteoric or rock formation water. Geologic setting, REE geochemistry and fluid inclusion studies suggest that mineralization was deposited from a solution generated by mixing of magmatic and meteoric water under epithermal conditions.展开更多
Rare earth elements(REEs)are widely applied in high-tech fields.However,their increasing presence in the food chain poses significant risks to human health.At present,little is known about the effects of organic matte...Rare earth elements(REEs)are widely applied in high-tech fields.However,their increasing presence in the food chain poses significant risks to human health.At present,little is known about the effects of organic matter on the distribution of ion-adsorbed REEs in soil aggregates during ecological restoration.Red soil derived from coarse-grained granite in Southern China is both prone to ecosystem degradation from soil erosion and rich in REEs.Understanding the distribution of REEs in soil aggregates undergoing ecological restoration is helpful to formulate effective measures for controlling the environmental migration of REEs.Four sites that had undergone different durations/degrees of ecological restoration were selected in the areas to analyze.REEs concentration of six different aggregates sizes(<0.25,0.25-0.5,0.5-1,1-2,2-5,and>5 mm)were analyzed and the enrichment coefficients were calculated in 4 sample sites of severe-degraded ecosystem in Changting County,Fujian Province,Southern China.The results showed that the total rare earth elements(TREEs)concentration in the aggregates increased from 213 mg kg^(-1) to 528 mg kg^(-1) with the extension of the ecological restoration time.At the initial stages of ecological restoration,there was no significant difference in the TREEs concentration among the six aggregates sizes.However,in the middle and late stages of restoration,the concentration of TREEs increased significantly with the decrease of aggregate size.The concentration of individual REEs showed three changing trends with sizes of aggregates during ecological restoration,respectively:1)no obvious regular change(S1),2)a V-shaped change trend(S2),and 3)increasing concentration with the decrease of aggregate size(S3 and S4).Ce and Eu showed a positive and negative anomaly in the soil aggregates,respectively.Moreover,the light rare earth elements(LREEs)were enriched,while the heavy rare earth elements(HREEs)were depleted during the initial stages,and the HREEs were enriched during the middle and late stages of restoration.The correlation coefficient between organic matter and REEs in aggregates was generally low;however,LREEs showed a stronger correlation with organic matter than that of HREEs during the initial stages of ecological restoration.The correlation between organic matter and HREEs gradually increased and even exceeded that of LREEs with on-going ecological restoration.The distribution of REEs concentration in degraded soil aggregates in Southern China showed obvious variability with the ecological restoration time.展开更多
Numerous lakes in western China are excellent sites for understanding environmental change.However,what dominates rare earth element(REE) variations are still under debate in the lake environmental research.In this st...Numerous lakes in western China are excellent sites for understanding environmental change.However,what dominates rare earth element(REE) variations are still under debate in the lake environmental research.In this study,we selected 28 surface sediment samples from 17 lakes(i.e.largescale lakes,small water bodies,etc.) in the QinghaiTibet Plateau and Xinjiang area.These samples were analyzed to reveal the behavior of the REEs and major elements.These REE patterns are characterized by light rare earth element(LREE) enrichment,weak Ce anomaly(0.84-0.98,0.94 on average) and negative Eu anomaly(0.53-1.00,0.67 on average).The homogeneous REE patterns may reflect similar REE of the source lithologys.However,the REE abundances showed some significant differences.In this study,water chemistry data analyses inferred that the highly REE values appear possibly in the saltwater lake,and also related to carbonate mineral,whereas p H played a minor role in REE concentrations.In large-scale lakes(e.g.Lake Bosten and Lake Ulungur),the results showed that the relatively larger REE values are in the margins of lakes.Moreover,lower REE contents are towards the central region.Comprehensive study suggested that five major factors control the REE contents:(1) The REE tends to increase with the increase of the weathering intensity.(2) Likewise,heavy mineral(i.e.rutile,anatase,zircon,etc.) are probably primary in these sediments because they are highly enriched in the REE.(3) The contribution of Fe-Mn oxides is significant in sediments because their concentrations highly correlate with the REE.(4) The carbonate mineral(mainly calcite) played a significant role on the REE values in the lakes because the REEs are incorporated into the carbonate minerals generating the low REE concentrations.(5) Major element analysis,mineral analysis,and grain-size data analysis showed that the REE distribution is chiefly influenced by finer grain-size component of lake sediments due to the decreasing proportion of quartz and feldspar than coarser one.Moreover,the clay minerals in finer grain-size sediments can highly absorb the REE.展开更多
1 Introduction The weathered crust rare earth deposits is one of the most significant rare earth deposits,which are mostly distributed in southern China,especially in the south of Jiangxi province(Chi et al.,2007).The...1 Introduction The weathered crust rare earth deposits is one of the most significant rare earth deposits,which are mostly distributed in southern China,especially in the south of Jiangxi province(Chi et al.,2007).The compositions of these deposits,which are weathered from igneous rocks such as granite through biological,physical or展开更多
The effects of rare earth elements(La,Sm)on the high-temperature(250℃)microstructure and mechanical properties of Al-Si-Cu alloys were analyzed.The experimental results show that with the addition of La and Sm,theα-...The effects of rare earth elements(La,Sm)on the high-temperature(250℃)microstructure and mechanical properties of Al-Si-Cu alloys were analyzed.The experimental results show that with the addition of La and Sm,theα-Al was significantly refined,and the eutectic Si changed from acicular to rod-like and granular.XRD and SEM analysis shows that the rare earth phases in the alloy were mainly AlSiRe and AlRe.Fracture morphology observations show the fracture mode of the alloy changes from brittle and ductile fracture to ductile fracture.With the increase of La or Sm contents,the mechanical properties of the alloys at 250℃ increase at first,and then decrease.When the contents of La and Sm are 0.4wt.%and 0.2wt.%,the tensile strength of the alloy reaches maximum of 143.91 MPa and 201.48 MPa,respectively.展开更多
The content and distribution pattern of rare earth elements(REEs)in surface sediments from the Eastern and Western Pacifi c Ocean,the Northern and Southern Atlantic Ocean,and the Southwestern Indian Ocean were explore...The content and distribution pattern of rare earth elements(REEs)in surface sediments from the Eastern and Western Pacifi c Ocean,the Northern and Southern Atlantic Ocean,and the Southwestern Indian Ocean were explored and the resources and geochemical characteristics of REEs in deep-ocean sediments from diff erent oceans were studied.The total REE abundances(ΣREE)in the diff erent oceans ranged as follows:Eastern Pacifi c,56.88–500.02μg/g;Western Pacifi c,290.68–439.94μg/g;Northern Atlantic,55.33–154.90μg/g;Southern Atlantic,40.83–69.30μg/g;and Southwestern Indian Ocean,20.24–64.76μg/g.Their corresponding LREE(La-Eu)/HREE(Gd-Lu)average values were 5.18,5.86,9.01,5.21,and 4.59,which indicated that the light REEs were all evidently enriched.δEu andδCe showed slight Eu-negative anomalies and signifi cant Ce-positive anomalies in all sediments.Although the contents of REEs in the sediments varied among the diff erent oceans,the distribution patterns of REEs were similar,and the correlation coeffi cient was greater than 0.9290.In the Eastern Pacifi c sediments,ΣREE showed a signifi cantly positive correlation with Co,Cu,Zn,Mn,Mo and a weak correlation with Fe.In the Western Pacifi c and Southern Atlantic sediments,ΣREE presented no obvious correlation and a weakly negative correlation with Co,Cu,Zn,Mn,Mo and Fe,respectively.ΣREE in the Southwestern Indian Ocean sediments positively correlated with Cu,Zn,Mn,Mo,Fe,and had a weakly negative correlation with Co.展开更多
The total content of light rare earth elements( LREEs) in the soil of navel orange orchards of Gannan area is greater than that of heavy rare earth elements( HREEs). Appropriate content of LREE can not only promote th...The total content of light rare earth elements( LREEs) in the soil of navel orange orchards of Gannan area is greater than that of heavy rare earth elements( HREEs). Appropriate content of LREE can not only promote the growth of navel oranges,and it is also conducive to human health. On the basis of exploring the correlations between the content of LREE in the soil of navel orange orchards of Gannan area and the contents of LREE in navel orange leaves and fruit,the influence mechanism of LREEs on the quality of navel oranges was revealed. In this study,with two Newhall navel orange orchards with different soil LREEs background levels in Xinfeng County as the research object,the changes in the content of LREE( lanthanum,La; cerium,Ce; praseodymium,Pr; neodymium,Nd) in leaves and fruit of navel orange at different growth stages were analyzed using Inductively Coupled Plasma-Mass Spectrometry( ICP-MS),and the correlations between the content of LREE in the soil,navel orange leaves and navel orange fruit were studied. The results showed that the contents of the four kinds of LREEs in the soil ranked as Ce > La > Nd > Pr,and there were significant differences among them( P < 0. 01). Navel orange leaves and fruit have selective and heterogenic absorption for LREEs. At different growth stages,La showed the highest accumulation amount in the leaves and fruit of navel orange; and the content of LREE in the leaves of navel orange increased first and then decreased,while that in the fruit of navel orange showed continuous decrease. During the migration of LREEs from soil to leaves to fruit,the content of LREE decreased rapidly as the migration distance increased. The accumulation amount of LREE in navel orange was positively correlated with the content of LREE in the soil. The correlation between the content of LREE in the leaves and fruit of navel orange was greatest. Among the four kinds of LREEs,the correlation of La was greatest,followed by Ce,indicating that the accumulation amount of LREE in the navel orange body was affected by the element types.展开更多
The present article is a review study on the types of rare earth elements(REEs),environmental and biological effects as well as the sources of emission of these elements as pollution in nature.The purpose of this stud...The present article is a review study on the types of rare earth elements(REEs),environmental and biological effects as well as the sources of emission of these elements as pollution in nature.The purpose of this study is to provide a vision in environmental planning and control of pollution caused by REEs.The evaluation of rare earth elements was studied in human life and its environmental and biological effects,which have particular importance and are entering the life cycle through industrial and mining pollution sources.Since mining activities intensify the dispersion of these elements in the environment and the existence of industrial factories located around urban drainage system plays a unique role in creating and spreading pollution caused by rare earth elements;As a result,two case studies were conducted on two mining and industrial areas.The first case is the Choghart mine in Yazd province as an example of mining pollution,and the second case study is performed on the Kor river as an example of industrial pollution which is caused by industrial activities around it,Then the results are well explained to show both two environments of litho and hydro.Due to this fact that produced environmental pollution can cause exchange pollutant compounds with the surrounding environment besides its long-lasting destructive effects;It can cause irreversible biological effects on living organisms.By targeting this evaluation,several techniques can be proposed to prevent the entry and dispersal of rare earth elements from pollution sources besides methods to reduce the damage of these elements to the ecosystem.展开更多
This study examines the rare earth elements and yttrium(REY)concentrations of twenty-five samples from the reef outcrop exposed along the Lianglitage Mountain in the Ordovician,Tarim Basin in China.The concentration a...This study examines the rare earth elements and yttrium(REY)concentrations of twenty-five samples from the reef outcrop exposed along the Lianglitage Mountain in the Ordovician,Tarim Basin in China.The concentration analysis provides constraints on the paleoenvironment during reef deposition.Based on the detailed sedimentology and petrographic work,we divide the reef facies into four sub-facies:the base facies,reef-core facies,reef-flank facies,and sealing facies.The geochemical data(such as major and trace elements,carbon and oxygen isotopes,and REYs)are further used to study the coeval seawater characteristics as well as potential diagenesis overprints.The result indicated that the diagenesis has little effect on the REY patterns of the reefal limestones.The REY concentrations of the reefal limestones are overall low(ranging from 3.69 to 19.60 ppm,arithmetic mean=10.22 ppm,SD=5.4).The PAAS-normalized REY patterns are consistently flat compared to the typical well-oxidized,shallow marine water patterns.However,the light REE(LREE)depletions,positive La anomalies,negative Ce anomalies and positive Y anomalies,suggest that these reefal limestones are likely an indicative of contemporaneous seawater REY signals.The seawater-like Y/Ho ratios(average at 37.51)further support that REY signals in these limestones are likely a reflection of seawater with little diagenetic modifications.The low Y/Ho ratios presented only in the reef-flank facies and sealing facies are likely a suggestion of detrital contamination.Hence,this study confirms that REY patterns of the limestones at the base facies and reef-core facies can record ancient seawater information,and reefs can be used as a potential geochemical proxy for paleoenvironment studies throughout the Earth’s history.展开更多
Based on the study of stratigraphy and fossils, the Early Permian ocean in eastern Kunlun is recognized as a kind of reef-island ocean, in which there exist many different kinds of sediment, including patch carbonate ...Based on the study of stratigraphy and fossils, the Early Permian ocean in eastern Kunlun is recognized as a kind of reef-island ocean, in which there exist many different kinds of sediment, including patch carbonate platform, reef fades, transitional facies and deep basin sediments. It has been found that the total contents of REEs increase gradually from carbonate platform facies to deep basin facies. Meanwhile, sediments of different facies have different REE distribution patterns and different Ce anomalies. Most of the sediments of patch carbonate platform facies or reef facies are characterized by extremely negative Ce anomalies or moderately negative Ce anomalies (Ce/Ce*=0.33 to 0.55), and medium or thin-bedded limestones of transitional facies by moderately negative Ce anomalies (Ce/Ce*=0.49 to 0.60). However, sediments of deep basin facies show weak or no negative Ce anomalies (Ce/Ce*=0.69 to 1.47), among which the value of Ce/Ce* in the radiolarian chert is 1.47.展开更多
The behavior of rare earth element Ce in 2090 Al Li alloys was studied by the method of low frequency internal friction.The results showed that rare earth element Ce can increase the activation energy of grain boundar...The behavior of rare earth element Ce in 2090 Al Li alloys was studied by the method of low frequency internal friction.The results showed that rare earth element Ce can increase the activation energy of grain boundary and improve the grain boundary strength of alloys.Rare earth element Ce can decrease the tendency of softening of elastic modulus of 2090 Al Li alloys after heat cycle and keep high elastic modulus of initial state.展开更多
Composite nickel hydroxide films were prepared by cathodic co electrodeposition from metal nitrate solution and characterized by cyclic voltammetry in 1.0 mol/L KOH solution. The codeposited light rare earth elements ...Composite nickel hydroxide films were prepared by cathodic co electrodeposition from metal nitrate solution and characterized by cyclic voltammetry in 1.0 mol/L KOH solution. The codeposited light rare earth elements were lanthanum, cerium, praseodymium and neodymium. The films were analyzed by spectrophotometry and optical transmission. The results of the cyclic voltammetry in 1.0 mol/L KOH solution showed that the current density for oxygen evolution at the film electrode was affected by the co deposited rare earth metal ions in the film. About 20 mA/cm 2 increase of current density for oxygen evolution was found when the film was obtained from the solution with cerium (7% v/v) and nickel (93% v/v) nitrate. The effects of galvanostatic cathodic current density for the film formation on the oxygen evolution at the film electrodes from the alkaline were discussed.展开更多
Information on rare earth elements(REEs)in soils and plants of the Qinghai-Tibet Plateau is very limited.Therefore,in this study,we performed field sampling to explore the geochemical signatures and human health risk ...Information on rare earth elements(REEs)in soils and plants of the Qinghai-Tibet Plateau is very limited.Therefore,in this study,we performed field sampling to explore the geochemical signatures and human health risk of REEs in soils and plants of the northeastern Qinghai-Tibet Plateau,China.A total of 127 soil samples and 127 plant samples were collected from the northeastern Qinghai-Tibet Plateau to acquire the geochemical signatures and related human health risks of REEs.The mean total concentrations of REEs in soils and plants of the study area reached 178.55 and 10.06 mg/kg,respectively.The light REEs in soils and plants accounted for 76%and 77%of the total REEs,respectively.REEs showed significantly homogenous distribution in soils but inhomogeneous distribution in plants of the study area.Characteristic parameters indicated that light REEs were enriched and fractionated significantly,while heavy REEs were moderately fractionated in soils and plants.REEs in soils and plants showed significantly negative Europium anomaly.Cerium showed slightly positive anomaly in plants and slight anomaly in soils.The normalized distribution patterns of REEs were generally similar in the analyzed soils and the corresponding plants of the study area.The average bio-concentration factor of REEs ranged from 0.0478(Scandium)to 0.0604(Europium),confirming a small accumulation of REEs by plants.Health risks caused by REEs in soils and plants were negligible,while risks for adults were lower than those for children.This study provides important information on REEs in soils and plants of the northeastern Qinghai-Tibet Plateau.展开更多
The distribution patterns of rare earth elements(REEs)in fine-grained materials in various depositions were often found to be similar to those of the aeolian sediments deposited in the Loess Plateau in North China and...The distribution patterns of rare earth elements(REEs)in fine-grained materials in various depositions were often found to be similar to those of the aeolian sediments deposited in the Loess Plateau in North China and the fine-grained materials were suggested to be derived from wind-blown dust.However,increasing evidence indicated that the REEs in the water-soluble portion of atmospheric depositions also displayed similar patterns to those of aeolian sediments.In this study,water-soluble REEs in three atmospheric depositions collected from different climatic zones in China were adsorbed with two adsorbents with distinct adsorption capacity,glass powder,and co-precipitated iron hydroxide.The results showed that the REEs adsorbed by the two adsorbents displayed patterns similar to those of the original atmospheric depositions.The typical characteristics of the REE patterns of atmospheric deposition can be well reproduced in the adsorbed REEs.The higher the REE concentrations in the atmospheric depositions,or the higher adsorption efficiency of the adsorbents,the better reproducibility of the REEs patterns.The results suggest that the REEs of the fine-grained materials in various sediments,which have a high adsorption capacity,especially those deposited in South China,may come from the water-soluble REEs in atmospheric deposition,and may not be appropriate tracers of wind-blown dust from North China.展开更多
This study demonstrated using yttrium(Y)as an indicator to estimate the total rare earth element and Y contents(REY)in coal-associated samples and to facilitate selection of samples with high REY assays in a fast and ...This study demonstrated using yttrium(Y)as an indicator to estimate the total rare earth element and Y contents(REY)in coal-associated samples and to facilitate selection of samples with high REY assays in a fast and inexpensive manner.More than 10 anthracite-associated samples were collected from each of three Pennsylvanian sites(sites B,J and C)based on Thorium gamma ray logging suggesting high REY content.Several samples from each site were analyzed by ICP-MS to determine the rare earth distribution patterns and to establish the site-specific linear equations of Y and REY.The Y contents of the remaining samples were measured by a portable X-ray fluorescence analyzer,and the REY values were estimated based on the site-specific linear equation developed earlier.R-squared values above 0.70 were obtained for all the estimation equations from all three sites on both a whole sample basis and an ash basis.Previously,ash content has been widely used as an indicator of high REY content.This may not be applicable for a specific site.Site B in this study is an example where ash contents could not be statistically correlated with REY,so using Y for estimation is more applicable.The demonstrated sample screening process is suitable for samples from sites that share more similar distribution patterns(either MREY or LREY or HREY)as well as for samples from sites that share multiple distribution patterns(LREY/MREY/HREY)depending on the desirable accuracy.The demonstrated process lowers the analytical cost from$70 to 80 dollars per sample to$10-15 per sample while significantly reducing the processing time and acid consumption for ICP digestion.This is particularly true when a relatively large sample size is involved,for example,100 samples from one site analyzed by ICP-MS/OES.展开更多
基金supported by Project of Basic Science Center of National Natural Science Foundation of China(72088101)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA14010101)+3 种基金National Key Research and Development Program of China(2017YFC0603101)National Natural Science Foundation of China(41872125,42002158)Scientific and Technological Project of RIPED(2021ycq01)the subject development project of RIPED(yjkt2019-3).
文摘Petrogenesis of lacustrine dolostone is closely related with paleo-lake water conditions.Here we report the high spatial-resolution petrographic and geochemical results of a lacustrine dolomite nodule from the Qingshankou Formation,the Songliao Basin.Sedimentary and elemental signatures confirm the protogenetic origin of this nodule and its effectiveness in recording geochemical characteristics of paleo-lake water during dolomitization.The low Y/Ho ratios,middle rare earth element(MREE)enrichment and subtle positive Eu anomalies within the nodule indicate a fresh water source.However,the Sr isotope values in the core of the nodule(0.7076-0.7080)are close to contemporaneous seawater(0.7074),yet different from the modern river(0.7120)and the host black shale(0.7100).On the premise of excluding the influence of hydrothermal fluids,the significantly low strontium isotope values of the lacustrine dolomite might be caused by seawater interference during dolomitization.Our findings demonstrate that lacustrine dolomite within black shales is not only a faithful tracer of diagenetic water environment,but also a novel and easily identified mineralogical evidence for episodic seawater intrusion event(91 Ma)in the Songliao Basin,which supplements other paleontological and geochemical evidence.
文摘The present work assesses the temporal distribution pattern and geochemical changes of rare earth elements and Yttrium, Scandium, Thorium, and Uranium delivery into the Oualidia lagoon. Two sediment cores were retrieved from the Oualidia lagoon and analyzed using neutron activation analysis. The results indicated that heavy rare earth elements are slightly enriched the sediment cores over light rare earth elements. The highest values of REEs were recorded in the top layers of the cores and depleted with depth, suggesting a possible change in factors controlling their accumulation, including mechanical, chemical, and environmental parameters such as weathering intensity, grain size, and Fe-Mn oxides. The sediments display positive Ce anomalies, which are probably related to the submarine weathering process and detrital input. Noting also the variation of hydrodynamics conditions and confinement of the upstream part of the lagoon played a key role in changing the sediment origins.Thus, further investigation of REEs origin in the Oualidia lagoon sediment is required to identify their sources,provenances, and the factors controlling their spatial and vertical distributions. However, these results provide baseline data of occurring changes in REEs geochemical composition and constitute a typical study case to understand the link between sedimentary and geochemistry processes in a lagoonal ecosystem.
文摘The present work investigates the influences of microalloying with rare earths on the mechanical properties of magnesium alloys.The amount of each rare earth element is controlled below 0.4 wt.%in order not to increase the cost of alloy largely.The synergic effects from the multi-microalloying with rare earths on the mechanical properties are explored.The obtained results show that the as-cast magnesium alloys multi-microalloying with rare earths possesses a quite high ductility with a tensile strain up to 25-30%at room temperature.Moreover,these alloys exhibit much better corrosion resistance than AZ31 alloy.The preliminary in situ neutron diffractions on the deformation of these alloys indicate that the multi-microalloying with rare earths seems to be beneficial for the activation of more slip systems.The deformation becomes more homogeneous and the resultant textures after deformation are weakened.
基金This research was supported by the National Key Basic Research and Development Program(No.2014CB238902)National Natural Science Foundation of China(No.41302128).
文摘The rare earth elements and yttrium(REY)of the K2 coal from the Moxinpo mine,Chongqing,were determined using inductively coupled plasma mass spectrometry(ICP-MS).The results show that REY are enriched in the K2 coal,with the average content up to 462 lg/g,much higher than average values of most coals in the world.The REY distribution patterns indicate that the light REY is enriched and show a well-pronounced Eu minimum.The fractionation of individual light-REY is higher than that of the heavy-REY.The REY distribution through the K2 coal seam shows that the top and bottom portion of the coal seam have a lower content of REY than the middle portion.Goyazite and rhabdophane were identified with a scanning electron microscope equipped with an energy-dispersed X-ray spectrometer(SEM-EDX).The REY distributions through the coal seam,SEM-EDX data and the correlation analysis between ash yields and the concentrations have revealed that the REY mainly occurs in the organic matter.The K2 coal is a potential rare-metal resource due to its high REY contents,and the coal ash could be regarded as a new and promising raw material for recovery of REY as a by-product.
基金This work was supported by the National Natural Science Foundation of China(Nos.21976047,21790373,and 51774104)the Ph.D Student Research and Innovation Fund of the Fundamental Research Funds for the Central Universities(No.3072019GIP1011)+1 种基金University and Local Integration Development Project of Yantai,China(No.2020 XDRHXMPT36)the Sino-Russian Cooperation Fund of Harbin Engineering University(No.2021HEUCRF004).
文摘With the increasing demand of rare earth metals in functional materials,recovery of rare earth elements(REEs)from secondary resources has become important for the green economy transition.Molten salt electrolysis has the advantages of low water consumption and low hazardous waste during REE recovery.This review systematically summarizes the separation and electroextraction of REEs on various reactive electrodes in different molten salts.It also highlights the relationship between the formed alloy phases and electrodeposition parameters,including applied potential,current,and ion concentration.Moreover,the feasibility of using LiF–NaF–KF electrolyte to recover REEs is evaluated through thermodynamic analysis.Problems related to REE separation/recovery the choice of electrolyte are discussed in detail to realize the low-energy and high current efficiency of practical applications.
基金carried out within the framework of the“Central Anatolian Fluorite Research Project”supported by General Directorate of Mineral Research and Exploration(MTA).
文摘Fluorite mineralization occurs along fractures and cracks of Middle Eocene and Pliocene limestones and marls in the north and northeast of the P?hrenk region (?i?ekdagi, Kirsehir). Tb/Ca ( Tb/La and Y/Ho ratios were obtained from REE contents of fluorites which have revealed that mineralization is of hydrothermal type. Negative Ce anomalies and positive Eu anomalies reflect that hydrothermal solutions once had high oxygen fugacity. Fluid inclusion studies indicate that homogenization temperatures of mineralization varied between 90oC and 200oC, and hydrothermal solutions are composed of NaCl + KCl + MgCl2 + H2O. In addition, salinity measurements show that hydrothermal solutions were mixed with meteoric or rock formation water. Geologic setting, REE geochemistry and fluid inclusion studies suggest that mineralization was deposited from a solution generated by mixing of magmatic and meteoric water under epithermal conditions.
基金This research was supported by the Industry-University Cooperation Project of Fujian Province(2020Y4101)the National Key Research and Development Program of China(2016YFC0502905).
文摘Rare earth elements(REEs)are widely applied in high-tech fields.However,their increasing presence in the food chain poses significant risks to human health.At present,little is known about the effects of organic matter on the distribution of ion-adsorbed REEs in soil aggregates during ecological restoration.Red soil derived from coarse-grained granite in Southern China is both prone to ecosystem degradation from soil erosion and rich in REEs.Understanding the distribution of REEs in soil aggregates undergoing ecological restoration is helpful to formulate effective measures for controlling the environmental migration of REEs.Four sites that had undergone different durations/degrees of ecological restoration were selected in the areas to analyze.REEs concentration of six different aggregates sizes(<0.25,0.25-0.5,0.5-1,1-2,2-5,and>5 mm)were analyzed and the enrichment coefficients were calculated in 4 sample sites of severe-degraded ecosystem in Changting County,Fujian Province,Southern China.The results showed that the total rare earth elements(TREEs)concentration in the aggregates increased from 213 mg kg^(-1) to 528 mg kg^(-1) with the extension of the ecological restoration time.At the initial stages of ecological restoration,there was no significant difference in the TREEs concentration among the six aggregates sizes.However,in the middle and late stages of restoration,the concentration of TREEs increased significantly with the decrease of aggregate size.The concentration of individual REEs showed three changing trends with sizes of aggregates during ecological restoration,respectively:1)no obvious regular change(S1),2)a V-shaped change trend(S2),and 3)increasing concentration with the decrease of aggregate size(S3 and S4).Ce and Eu showed a positive and negative anomaly in the soil aggregates,respectively.Moreover,the light rare earth elements(LREEs)were enriched,while the heavy rare earth elements(HREEs)were depleted during the initial stages,and the HREEs were enriched during the middle and late stages of restoration.The correlation coefficient between organic matter and REEs in aggregates was generally low;however,LREEs showed a stronger correlation with organic matter than that of HREEs during the initial stages of ecological restoration.The correlation between organic matter and HREEs gradually increased and even exceeded that of LREEs with on-going ecological restoration.The distribution of REEs concentration in degraded soil aggregates in Southern China showed obvious variability with the ecological restoration time.
基金supported by a grant from Research Fund for the Doctoral Program of Higher Education of East China University of Technology (DHBK2019012)Key Laboratory for Digital Land and Resources of Jiangxi Province,East China University of Technology (DLLJ202018)。
文摘Numerous lakes in western China are excellent sites for understanding environmental change.However,what dominates rare earth element(REE) variations are still under debate in the lake environmental research.In this study,we selected 28 surface sediment samples from 17 lakes(i.e.largescale lakes,small water bodies,etc.) in the QinghaiTibet Plateau and Xinjiang area.These samples were analyzed to reveal the behavior of the REEs and major elements.These REE patterns are characterized by light rare earth element(LREE) enrichment,weak Ce anomaly(0.84-0.98,0.94 on average) and negative Eu anomaly(0.53-1.00,0.67 on average).The homogeneous REE patterns may reflect similar REE of the source lithologys.However,the REE abundances showed some significant differences.In this study,water chemistry data analyses inferred that the highly REE values appear possibly in the saltwater lake,and also related to carbonate mineral,whereas p H played a minor role in REE concentrations.In large-scale lakes(e.g.Lake Bosten and Lake Ulungur),the results showed that the relatively larger REE values are in the margins of lakes.Moreover,lower REE contents are towards the central region.Comprehensive study suggested that five major factors control the REE contents:(1) The REE tends to increase with the increase of the weathering intensity.(2) Likewise,heavy mineral(i.e.rutile,anatase,zircon,etc.) are probably primary in these sediments because they are highly enriched in the REE.(3) The contribution of Fe-Mn oxides is significant in sediments because their concentrations highly correlate with the REE.(4) The carbonate mineral(mainly calcite) played a significant role on the REE values in the lakes because the REEs are incorporated into the carbonate minerals generating the low REE concentrations.(5) Major element analysis,mineral analysis,and grain-size data analysis showed that the REE distribution is chiefly influenced by finer grain-size component of lake sediments due to the decreasing proportion of quartz and feldspar than coarser one.Moreover,the clay minerals in finer grain-size sediments can highly absorb the REE.
基金supported by the National Natural Science Foundation of China (Grant No. 41302030)Fundamental Research Project of Chinese Academy of Geological Sciences (Grant No. YYWF201619)+1 种基金National Key R&D Program of China (Grant No.2016YFC0600605)China Geological Survey Program (DD20179152)
文摘1 Introduction The weathered crust rare earth deposits is one of the most significant rare earth deposits,which are mostly distributed in southern China,especially in the south of Jiangxi province(Chi et al.,2007).The compositions of these deposits,which are weathered from igneous rocks such as granite through biological,physical or
基金the National Key Research and Development Program of China(No.2016YFB0301003)。
文摘The effects of rare earth elements(La,Sm)on the high-temperature(250℃)microstructure and mechanical properties of Al-Si-Cu alloys were analyzed.The experimental results show that with the addition of La and Sm,theα-Al was significantly refined,and the eutectic Si changed from acicular to rod-like and granular.XRD and SEM analysis shows that the rare earth phases in the alloy were mainly AlSiRe and AlRe.Fracture morphology observations show the fracture mode of the alloy changes from brittle and ductile fracture to ductile fracture.With the increase of La or Sm contents,the mechanical properties of the alloys at 250℃ increase at first,and then decrease.When the contents of La and Sm are 0.4wt.%and 0.2wt.%,the tensile strength of the alloy reaches maximum of 143.91 MPa and 201.48 MPa,respectively.
基金Supported by the Basic Scientifi c Fund for National Public Research Institutes of China(No.2020Q10)and the China Ocean Mineral Resources R&D Association(Nos.DY135-E2-1-07,DY135-E2-4)。
文摘The content and distribution pattern of rare earth elements(REEs)in surface sediments from the Eastern and Western Pacifi c Ocean,the Northern and Southern Atlantic Ocean,and the Southwestern Indian Ocean were explored and the resources and geochemical characteristics of REEs in deep-ocean sediments from diff erent oceans were studied.The total REE abundances(ΣREE)in the diff erent oceans ranged as follows:Eastern Pacifi c,56.88–500.02μg/g;Western Pacifi c,290.68–439.94μg/g;Northern Atlantic,55.33–154.90μg/g;Southern Atlantic,40.83–69.30μg/g;and Southwestern Indian Ocean,20.24–64.76μg/g.Their corresponding LREE(La-Eu)/HREE(Gd-Lu)average values were 5.18,5.86,9.01,5.21,and 4.59,which indicated that the light REEs were all evidently enriched.δEu andδCe showed slight Eu-negative anomalies and signifi cant Ce-positive anomalies in all sediments.Although the contents of REEs in the sediments varied among the diff erent oceans,the distribution patterns of REEs were similar,and the correlation coeffi cient was greater than 0.9290.In the Eastern Pacifi c sediments,ΣREE showed a signifi cantly positive correlation with Co,Cu,Zn,Mn,Mo and a weak correlation with Fe.In the Western Pacifi c and Southern Atlantic sediments,ΣREE presented no obvious correlation and a weakly negative correlation with Co,Cu,Zn,Mn,Mo and Fe,respectively.ΣREE in the Southwestern Indian Ocean sediments positively correlated with Cu,Zn,Mn,Mo,Fe,and had a weakly negative correlation with Co.
基金Supported by National Natural Science Foundation of China(31760551)Jiangxi Natural Science Foundation(20152ACB21002)Collaborative Innovation Special Funds of Jiangxi Academy of Sciences(2013-XTPH1-05)
文摘The total content of light rare earth elements( LREEs) in the soil of navel orange orchards of Gannan area is greater than that of heavy rare earth elements( HREEs). Appropriate content of LREE can not only promote the growth of navel oranges,and it is also conducive to human health. On the basis of exploring the correlations between the content of LREE in the soil of navel orange orchards of Gannan area and the contents of LREE in navel orange leaves and fruit,the influence mechanism of LREEs on the quality of navel oranges was revealed. In this study,with two Newhall navel orange orchards with different soil LREEs background levels in Xinfeng County as the research object,the changes in the content of LREE( lanthanum,La; cerium,Ce; praseodymium,Pr; neodymium,Nd) in leaves and fruit of navel orange at different growth stages were analyzed using Inductively Coupled Plasma-Mass Spectrometry( ICP-MS),and the correlations between the content of LREE in the soil,navel orange leaves and navel orange fruit were studied. The results showed that the contents of the four kinds of LREEs in the soil ranked as Ce > La > Nd > Pr,and there were significant differences among them( P < 0. 01). Navel orange leaves and fruit have selective and heterogenic absorption for LREEs. At different growth stages,La showed the highest accumulation amount in the leaves and fruit of navel orange; and the content of LREE in the leaves of navel orange increased first and then decreased,while that in the fruit of navel orange showed continuous decrease. During the migration of LREEs from soil to leaves to fruit,the content of LREE decreased rapidly as the migration distance increased. The accumulation amount of LREE in navel orange was positively correlated with the content of LREE in the soil. The correlation between the content of LREE in the leaves and fruit of navel orange was greatest. Among the four kinds of LREEs,the correlation of La was greatest,followed by Ce,indicating that the accumulation amount of LREE in the navel orange body was affected by the element types.
文摘The present article is a review study on the types of rare earth elements(REEs),environmental and biological effects as well as the sources of emission of these elements as pollution in nature.The purpose of this study is to provide a vision in environmental planning and control of pollution caused by REEs.The evaluation of rare earth elements was studied in human life and its environmental and biological effects,which have particular importance and are entering the life cycle through industrial and mining pollution sources.Since mining activities intensify the dispersion of these elements in the environment and the existence of industrial factories located around urban drainage system plays a unique role in creating and spreading pollution caused by rare earth elements;As a result,two case studies were conducted on two mining and industrial areas.The first case is the Choghart mine in Yazd province as an example of mining pollution,and the second case study is performed on the Kor river as an example of industrial pollution which is caused by industrial activities around it,Then the results are well explained to show both two environments of litho and hydro.Due to this fact that produced environmental pollution can cause exchange pollutant compounds with the surrounding environment besides its long-lasting destructive effects;It can cause irreversible biological effects on living organisms.By targeting this evaluation,several techniques can be proposed to prevent the entry and dispersal of rare earth elements from pollution sources besides methods to reduce the damage of these elements to the ecosystem.
基金supported by the National Natural Science Foundation of China(grant number 51574208)the National 973 Program of China(grant number 2012CB214802)+1 种基金the China Geological Survery Project(grant number DD20190217)the China Scholar Council(grant number 201606400023)for providing the financial support
文摘This study examines the rare earth elements and yttrium(REY)concentrations of twenty-five samples from the reef outcrop exposed along the Lianglitage Mountain in the Ordovician,Tarim Basin in China.The concentration analysis provides constraints on the paleoenvironment during reef deposition.Based on the detailed sedimentology and petrographic work,we divide the reef facies into four sub-facies:the base facies,reef-core facies,reef-flank facies,and sealing facies.The geochemical data(such as major and trace elements,carbon and oxygen isotopes,and REYs)are further used to study the coeval seawater characteristics as well as potential diagenesis overprints.The result indicated that the diagenesis has little effect on the REY patterns of the reefal limestones.The REY concentrations of the reefal limestones are overall low(ranging from 3.69 to 19.60 ppm,arithmetic mean=10.22 ppm,SD=5.4).The PAAS-normalized REY patterns are consistently flat compared to the typical well-oxidized,shallow marine water patterns.However,the light REE(LREE)depletions,positive La anomalies,negative Ce anomalies and positive Y anomalies,suggest that these reefal limestones are likely an indicative of contemporaneous seawater REY signals.The seawater-like Y/Ho ratios(average at 37.51)further support that REY signals in these limestones are likely a reflection of seawater with little diagenetic modifications.The low Y/Ho ratios presented only in the reef-flank facies and sealing facies are likely a suggestion of detrital contamination.Hence,this study confirms that REY patterns of the limestones at the base facies and reef-core facies can record ancient seawater information,and reefs can be used as a potential geochemical proxy for paleoenvironment studies throughout the Earth’s history.
文摘Based on the study of stratigraphy and fossils, the Early Permian ocean in eastern Kunlun is recognized as a kind of reef-island ocean, in which there exist many different kinds of sediment, including patch carbonate platform, reef fades, transitional facies and deep basin sediments. It has been found that the total contents of REEs increase gradually from carbonate platform facies to deep basin facies. Meanwhile, sediments of different facies have different REE distribution patterns and different Ce anomalies. Most of the sediments of patch carbonate platform facies or reef facies are characterized by extremely negative Ce anomalies or moderately negative Ce anomalies (Ce/Ce*=0.33 to 0.55), and medium or thin-bedded limestones of transitional facies by moderately negative Ce anomalies (Ce/Ce*=0.49 to 0.60). However, sediments of deep basin facies show weak or no negative Ce anomalies (Ce/Ce*=0.69 to 1.47), among which the value of Ce/Ce* in the radiolarian chert is 1.47.
文摘The behavior of rare earth element Ce in 2090 Al Li alloys was studied by the method of low frequency internal friction.The results showed that rare earth element Ce can increase the activation energy of grain boundary and improve the grain boundary strength of alloys.Rare earth element Ce can decrease the tendency of softening of elastic modulus of 2090 Al Li alloys after heat cycle and keep high elastic modulus of initial state.
文摘Composite nickel hydroxide films were prepared by cathodic co electrodeposition from metal nitrate solution and characterized by cyclic voltammetry in 1.0 mol/L KOH solution. The codeposited light rare earth elements were lanthanum, cerium, praseodymium and neodymium. The films were analyzed by spectrophotometry and optical transmission. The results of the cyclic voltammetry in 1.0 mol/L KOH solution showed that the current density for oxygen evolution at the film electrode was affected by the co deposited rare earth metal ions in the film. About 20 mA/cm 2 increase of current density for oxygen evolution was found when the film was obtained from the solution with cerium (7% v/v) and nickel (93% v/v) nitrate. The effects of galvanostatic cathodic current density for the film formation on the oxygen evolution at the film electrodes from the alkaline were discussed.
基金the One Hundred Talents Program of Chinese Academy of Sciences(Y610061033)the Kunlun Talent Action Plan of Qinghai Province,China(E140WX42)+2 种基金the Science and Technology Plan Protect of Qinghai Province,China(2021-ZJ-T07)the Taishan Scholar Program of Shandong Province,China(tsqn201812116)the Two-Hundred Talents Plan of Yantai City of Shandong Province,China。
文摘Information on rare earth elements(REEs)in soils and plants of the Qinghai-Tibet Plateau is very limited.Therefore,in this study,we performed field sampling to explore the geochemical signatures and human health risk of REEs in soils and plants of the northeastern Qinghai-Tibet Plateau,China.A total of 127 soil samples and 127 plant samples were collected from the northeastern Qinghai-Tibet Plateau to acquire the geochemical signatures and related human health risks of REEs.The mean total concentrations of REEs in soils and plants of the study area reached 178.55 and 10.06 mg/kg,respectively.The light REEs in soils and plants accounted for 76%and 77%of the total REEs,respectively.REEs showed significantly homogenous distribution in soils but inhomogeneous distribution in plants of the study area.Characteristic parameters indicated that light REEs were enriched and fractionated significantly,while heavy REEs were moderately fractionated in soils and plants.REEs in soils and plants showed significantly negative Europium anomaly.Cerium showed slightly positive anomaly in plants and slight anomaly in soils.The normalized distribution patterns of REEs were generally similar in the analyzed soils and the corresponding plants of the study area.The average bio-concentration factor of REEs ranged from 0.0478(Scandium)to 0.0604(Europium),confirming a small accumulation of REEs by plants.Health risks caused by REEs in soils and plants were negligible,while risks for adults were lower than those for children.This study provides important information on REEs in soils and plants of the northeastern Qinghai-Tibet Plateau.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 41473093 and 41271212)。
文摘The distribution patterns of rare earth elements(REEs)in fine-grained materials in various depositions were often found to be similar to those of the aeolian sediments deposited in the Loess Plateau in North China and the fine-grained materials were suggested to be derived from wind-blown dust.However,increasing evidence indicated that the REEs in the water-soluble portion of atmospheric depositions also displayed similar patterns to those of aeolian sediments.In this study,water-soluble REEs in three atmospheric depositions collected from different climatic zones in China were adsorbed with two adsorbents with distinct adsorption capacity,glass powder,and co-precipitated iron hydroxide.The results showed that the REEs adsorbed by the two adsorbents displayed patterns similar to those of the original atmospheric depositions.The typical characteristics of the REE patterns of atmospheric deposition can be well reproduced in the adsorbed REEs.The higher the REE concentrations in the atmospheric depositions,or the higher adsorption efficiency of the adsorbents,the better reproducibility of the REEs patterns.The results suggest that the REEs of the fine-grained materials in various sediments,which have a high adsorption capacity,especially those deposited in South China,may come from the water-soluble REEs in atmospheric deposition,and may not be appropriate tracers of wind-blown dust from North China.
基金the Department of Energy[Grant Number DE-FE-0030146]。
文摘This study demonstrated using yttrium(Y)as an indicator to estimate the total rare earth element and Y contents(REY)in coal-associated samples and to facilitate selection of samples with high REY assays in a fast and inexpensive manner.More than 10 anthracite-associated samples were collected from each of three Pennsylvanian sites(sites B,J and C)based on Thorium gamma ray logging suggesting high REY content.Several samples from each site were analyzed by ICP-MS to determine the rare earth distribution patterns and to establish the site-specific linear equations of Y and REY.The Y contents of the remaining samples were measured by a portable X-ray fluorescence analyzer,and the REY values were estimated based on the site-specific linear equation developed earlier.R-squared values above 0.70 were obtained for all the estimation equations from all three sites on both a whole sample basis and an ash basis.Previously,ash content has been widely used as an indicator of high REY content.This may not be applicable for a specific site.Site B in this study is an example where ash contents could not be statistically correlated with REY,so using Y for estimation is more applicable.The demonstrated sample screening process is suitable for samples from sites that share more similar distribution patterns(either MREY or LREY or HREY)as well as for samples from sites that share multiple distribution patterns(LREY/MREY/HREY)depending on the desirable accuracy.The demonstrated process lowers the analytical cost from$70 to 80 dollars per sample to$10-15 per sample while significantly reducing the processing time and acid consumption for ICP digestion.This is particularly true when a relatively large sample size is involved,for example,100 samples from one site analyzed by ICP-MS/OES.
