Rare earth element content in the SPM of Daliao river system and its comparison with that in the sediments, loess and soils in China

Content and distribution patterns of rare earth dements （REEs） in the suspended particulate material （SPM） of Daliao River system were investigated and compared with those in the fiver and sea sediments, loess, and soils of China. Twenty-seven samples of SPM were taken in Daliao River system and digested with various acids followed by ICP-MS analysis for REEs and ICP-OES analysis for Al, Fe, Mn, Ti, Mg, Ca, Na, and K, to measure the total concentrations of these elements. Results indicated that the spatial change in the content of REEs was great, with the coefficient of variance （CV） from 84% to 105%, while the contents of REEs were significantly correlated with each other. Chondrite-normalized patterns of REEs were characterized by higher enrichment of light REEs than heavy REEs, and a depletion of Eu in the SPM was generally found. The positive anomaly of Eu in the SPM of Xi River was due to anthropogenic source in Shenyang City. Furthermore, chondfite- and upper continent crust-normalized patterns of REEs in the SPM of Daliao River system, sediments of Yangtze River and Yellow River, sediments of Yellow Sea, East Sea, South Sea of China, and loess and soil of China, were very similar to one another. These demonstrated that the weathering and sedimentary processes resulted in constant REE distribution not only in the typical sedimentary rocks, but also in the modem riverine particle, sea sediments, loess, and soils.     

Rare earth elements distribution in marine sediments of Malaysia coasts

In the east coast Peninsular Malaysia region,sediments are transported by several rivers from the east Malaysia into the South China Sea estuary.In the vicinity of the five river estuaries core sediments were collected in order to investigate rare earth elements(REEs) profile.Core sediments were divided into strata of between 2 to 4 cm intervals and prepared for analyzing by ICP-AES.REE concentrations of 54.3 μg/gr at 24-26 cm in EC4 increased to 114.1 μg/gr at 20-22 cm in EC5.The measured concentration of ...     

Rare earth element geochemistry in the inner shelf of the East China Sea and its implication to sediment provenances

Gravity core EC2005, located in the mud wedge off the Zhejiang-Fujian coast in the inner shelf of the East China Sea (ECS), was analyzed for its lithology, grain size, rare earth elements (REE) and AMS14C dating. Results revealed high-resolution paleoenvironmental evolution and multiple switches of sediment provenances in the inner shelf of ECS. The lithology, grain size and REE concentrations of sediments varied significantly down the core. Mean grain size ranged from 8 to 121 μm, and the values of ΣREE were 152.8-227.9 μg/g. The chondrite- and shale-normalized REE patterns indicated their similarity to the terrigenous sediments in the study area. Between 17.3-12.3 ka BP the sediments in the inner shelf of ECS were mainly originated from local drainage basins. The source then gradually switched to the Yangtze River between 12.3 and 9.8 ka BP. Since about 10-9.8 ka BP, the sediments in the study area were dominantly derived from the Yangtze River. The continuous rising of sea level and formation of coastal current along the inner shelf played a key role in the switches of sediment provenances.     

Concentrations and Distribution Patterns of Rare Earth Elements in Water Body from Intertidal Flat of Tianjin and Influence of Various Factors

Concentrations and distribution patterns of rare earth elements(REEs)in the intertidal flat of Tianjin were studied using P507 resin and ICP-MS analytical technology. The results show that average concentrations of REEs in the filtered(dissolved REEs), unfiltered and interstitial water are 0.461 μg·L-1, 4.98 μg·L-1 and 0.845 μg·L-1, respectively. Their distribution patterns are similar to those in inland natural rivers, but quite different from those in oceans. The average concentrations of REEs in sediments and suspended matters are 161.2 mg·L-1 and 168.1 mg·L-1, respectively, which are much lower than those in sediments of natural rivers but higher than those in sediments of the continental shelf of East China Sea. It is suggested that REEs in sediments and suspended matters of intertidal flat can have mainly originated from terrestrial soils and thus their transportation and transformation processes are similar with those in rivers, and different from those in continental shelves. Pollutants discharged into the Bohai Bay do·not cause significant effect on REEs in the intertidal flat of Tianjin yet.     

Enrichment of REEs in polymetaUic nodules and crusts and its potential for exploitation

Polymetallic nodules and crusts are two of the most important mineral deposits in the ocean.They are rich in rare earth elements (REEs),iron,manganese,copper,cobalt,nickel,and other useful metals.This paper discussed the analysis of 25 nodule and crust samples collected from the South China Sea,the Pacific,Atlantic,and Indian Oceans.The samples were analyzed for REE content by ICP-MS/AES. The average REE concentration was found to be 1096.96×10-6 in the nodules and 1623.88×10-6 in the crusts.Both of these values are much higher than those recorded in Earth’s dry-land crust and sedimentary rocks.This REE enrichment is mainly controlled by the absorption of ferromanganese oxides and clay minerals in the nodules and crusts and the high levels of REEs in seawater and sediments.High cerium enrichment in the nodules and crusts may lead to more effective exploitation of REEs in the future.     

Characteristics and environmental significance of rare earth elements in PM_(2.5) of Nanchang,China

Concentrations of sixteen rare earth elements(REEs) in PM_(2.5) and potential-source samples, collected in Nanchang city in mid-September 2013, were determined by inductively coupled plasma mass spectrometry(ICP-MS). The results showed that the concentrations of total REEs(ΣREE) ranged from 78.76 to 1351 ng/mg. The order of REEs in PM_(2.5) samples showed the anthropogenic effects, Ce and Eu were affected more than the other REEs according to the enrichment factors. The results of chondrite-normalized REEs patterns and characteristic parameters showed evident light REEs fractionation, and positive anomalies of Ce and Eu in PM_(2.5). The other non-local pollution sources affected the PM_(2.5) samples, according to the triangular diagram of La, Ce and Sm compositions and plot of ΣREE vs δEu. Moreover, plot of(La/Sm)_N vs(Gd/Yb)_N revealed the effects of local sources. In conclusion, the REEs in potential-source samples were close to the background of local soil, while the REEs in PM_(2.5) samples in Nanchang city were jointly affected by the investigated local sources and other non-local sources.     

Rare Earth Elements Compositions and Genesis of Xinhua Large-Scale Phosphorite Deposit in Western Guizhou, China

Zhijin County in Western Guizhou is one of the most important production areas of phosphorites in China. In order to investigate genesis of the phosphorites, their REE compositions were analyzed by using inductively coupled plasma emission mass spectrometry (ICP-MS) method. For comparison, phosphorites from the Lower Cambrian black rock series in Southern China, such as Zunyi in Guizhou and Zhangjiajie in Hunan Province, were also analyzed. The analytical data show that: (1) Xinhua phosphorites possess a quite high and greatly varied total rare earth elements (ΣREE), which varying between 164.23×10-6 and 1395.01×10-6 with average of 642.54×10-6, remarkable differentiation between light (LREE) and heavy rare earth elements (HREE), and the ΣLREE/ΣHREE ratios varying between 5.04 and 6.52. The ΣREE and ΣLREE/ΣHREE ratios of the Zunyi and Zhangjiajie phosphorites are 156.69×10-6～637.41×10-6 with average of 431.75×10-6 and 3.17～6.95 with average of 4.37 respectively; (2) All the phosphorites from Xinhua, Zunyi and Zhangjiajie show remarkable negative Ce anomalies. Besides, the Xinhua phosphorites possess lower δCe, which varying between 0.26 and 0.53 with average of 0.35, while δCe of the Zunyi and Zhangjiajie phosphorites are 0.30～0.66 with average of 0.47, suggesting that all of the phosphorites are typical marine sediments deposited mainly in ancient peri-continental seas, and the depositional position of the Xinhua phosphorite might be deeper; (3) Most phosphorites from Xinhua, Zunyi and Zhangjiajie possess unremarkable positive Eu anomaly, and only a few of samples show obvious ones. The δEu varies between 0.98 and 2.4, suggesting that hot (>200 ℃) and strong reductive hydrothermal fluids might have been involved in genesis of the phosphorites; (4) The Xinhua phosphorite is relatively depleted in HREE, and LaN/NdN and δY of most samples are >1 and >1.5 respectively. Besides, there exists no correlation between δY and δCe, suggesting that the phosphorite was subjected to quite strong weathering and leaching processes, and catagenesis do not greatly modify its REE compositions.     

Content of rare earth elements in Salvia miltiorrhiza bunge from different areas

Salvia miltiorrhiza bunge(SMB) has been widely used as a traditional Chinese medicine for a long time,and today more and more attention has been paid to the effective components in Chinese traditional medicine,especially to rare earth elements(REEs).14 kinds of REEs in SMB from different areas were analyzed by the methods of ICP-MS.The results showed that the total concentration of REEs(as REO,the same below) ranged from 8.43(as dry weight,the same below) to 37.30 mg/kg,and the concentrations of La,Ce and Nd were higher than 2 mg/kg except Nd in SMB from Beijing.So the total concentration of REEs in SMB was much higher than that in rice,corn and barley,which could be the mechanism of curative effect of SMB on cardiovascular cerebrovascular system,digestive system,respiratory system,countershock and antibiotic.The character of other elements and the content of REEs in soil from different areas should be responsible for the difference,but the allocation mechanism of REEs in SMB should be further studied.     

Distribution of rare earth elements in agricultural soil and human body(scalp hair and urine) near smelting and mining areas of Hezhang,China

Rare earth elements(REEs) in recent decade are widely used and lead to the accumulation of REE in the environment and human body. The aim of this study was to evaluate the concentrations of REEs in soil and human body(scalp hair and urine) of people living in agricultural soil near smelting and mining areas in Hezhang County, China. The results showed that mean concentrations of determined REEs in agricultural soil from smelting areas were higher than background. However, concentration was slightly higher in soil in mining area. In addition, REEs concentrations of hair and urine in smelting areas were higher than those in mining areas. ΣREEs for soil in mining and smelting areas were 177.79 and 277.06 mg/kg, respectively. ΣREEs for hair in mining and smelting were 1.13 and 1.55 mg/kg, respectively, and ΣREEs for urine in mining and smelting were 0.58 and 0.59 μg/L, respectively. Results showed that La, Ce and Nd were enriched in soil, hair and urine. Eu in smelting area showed a positive anomaly. In smelting and mining areas, females were more likely than male to expose to REEs. The relationship between REEs concentration and age group showed that hair's high concentrations of REE existed in 18–40 years age for people from smelting areas and females from mining areas. While high concentrations distributed in the age of 41–65 for males from mining area. However, urine did not present similar distribution for different age group. Compared with hair and urine, soil showed the same distribution of REEs. And according to the Ce/Ce* value vs. La_N/Yb_N ratio showed that hair and soil tended to increase, with the stability of Ce/Ce* value. Thus the distribution of REEs in soil was closely related with the accumulation in human body. This is a preliminary study which may be suggested to the other research, and this study data may be useful for adding up the data pool on REEs levels in China.     

Effects of the accumulation of the rare earth elements on soil macrofauna community

The accumulation of rare earth elements(REEs)in soil has occurred due to the pollution caused by the exploitation of rare earth resources and the wide rare earth fertilizers in agriculture.The accumulation of REEs has a toxic effect on the soil macrofauna community.12study samples were collected near a mine tailings dam with a large amount of REEs by distance gradient sample method.The total concentration of REEs was analyzed and the results were compared with that of the sample from a control site.The effects of the amount of REEs in the soil on the soil macrofauna community were also analyzed.The results showed that the accumulation of REEs in soil was significant in the study area and its concentration was strongly correlated with the distance from the pollution source.One-way ANOVA analysis indicated the significant differences in soil macrofauna communities among the different sites.The ordination obtained through the redundancy analysis demonstrated that the concentration of REEs and the total nitrogen,total potassium and pH,had affected the soil macrofauna community.A small amount of REEs in the soil can promote the diversity of soil macrofauna,but a large amount of REEs can reduce its diversity.The insect groups of Carabidae and Dermaptera were comparatively sensitive to the concentration of REEs in soil,and could be used as an indicator of soil pollution of REEs.However,the Formicidae and Stibaropus formosanus exhibited a high tolerance to REEs in soil.We believe that it is very important for the soil environment protection to strictly control the application of the rare earth fertilizers in agriculture in China.     

REEs fractionation and sedimentary implication in surface sediments from eastern South China Sea

To get features of rare earth elements(REEs)fractionation,106 surface sediment samples from eastern South China Sea were determined for REEs combined with major and trace elements by ICP-MS.The distribution pattern of REEs,strong correlation between REEs and Al,North American shale composite(NASC)normalization all suggest a dominant crustal source for REEs in the research area.However, distinct fractionation among REEs was observed in surface sediment from area with water depth over 2000 m,confirmed by the strong positive correlation among light rare earth elements(LREEs)and among heavy rare earth elements(HREEs)but weaker relationship between LREEs and HREEs.Eluviation by Cl – might be a key role on the fractionation of REEs,comparing with factors such as grain size,co-precipitation with Fe and Mn hydroxide,calcareous and siliceous biogenic precipitation.The fractionation among REEs could be used as index to illustrate the sedimentary environment in reverse.     

Rare earth element geochemistry of groundwaters from coal bearing aquifer in Renlou coal mine, northern Anhui Province, China

Rare earth element (REE) concentrations of two different types of groundwaters (high SO42–water-SW and high alkaline waterCW) from coal bearing aquifer (–400~–280 m) in Renlou coal mine,northern Anhui Province,China were measured.The results indicated that they had different REE characteristics: the total concentrations of REEs (ΣREE) of SW were lower than those of CW in general although they all had heavy REEs enriched relative to light REEs.The dissolved REE inorganic species of SW included Ln3+,LnCO3+,LnSO4+,Ln(CO3)2– and Ln(SO4)2–,whereas the CW are Ln(CO3)2– and LnCO3+ dominant,and the proportions of Ln(CO3)2– increased while other species decreased with pH increasing.Combined with correlation analysis,the enrichment and fractionation of SW (low alkaline water) were considered to be affected by alkaline concentrations via affecting the types and proportions of REE inorganic species.However,the effect of alkaline concentrations to the enrichment and fractionation of REEs of CW (high alkaline water) was less important than total dissolved solids and pH,which reflected the contribution from different rocks they flowed over,different degrees of water-rock interactions and/or REE solid-liquid partition coefficients.     

A novel method to assess the effect of diagenesis on fossil teeth:Rare earth element signatures

An attempt was made to test the validity of the signatures of rare earth elements (REE) as a tool to judge the effect of diagenesis on fossil teeth. Sample REE contents and features of fossil teeth and sediments from Jinsha Relics, Sichuan, Southwest China were analyzed. The difference in REE content between fossil teeth is significantly greater than that between sediments at the Jinsha Relics. Chondrite-normalized REE patterns showed that obvious LREE enrichment and strong Ce and HREE depletion occurred in all fossil teeth samples. Meanwhile δCe and δEu values varied more dramatically in fossil teeth than in sediments. Accordingly, low content, LREE enrichment, strong Ce depletion, the significantly positive correlation between LREE/HREE and δCe, and unchanged (La/Yb)N demonstrated that the fossil teeth from Jinsha Relics have not been contaminated by diagenesis. The REE signature might be a potential proxy to assess the effect of diagenesis on fossil teeth.     

Adsorption ability of rare earth elements on clay minerals and its practical performance

The adsorption behaviors of rare earth elements on clay minerals would have great influence on the mineralization process and the leaching process of the ion-adsorption type rare earths ore.In this work,the adsorption thermodynamics of REEs on kaolin were investigated thoroughly and systematically.The experimental results showed that the adsorption characteristics of La,Nd,Y on kaolin did fit well with the Langmuir isotherm model and their saturated adsorption capacities were 1.731,1.587 and 0.971 mg/g,respectively.The free energy change(ΔG)values were –16.91 kJ/mol(La),–16.05 kJ/mol(Nd)and –15.58 kJ/mol(Y),respectively.The negative values of ΔG demonstrated that the adsorption of rare earth on kaolin was a spontaneously physisorption process.The deposit characteristic of the volcanic ion-adsorption type rare earths ore and the behavior of the rare earth in the column leaching process were also developed here.With the increase of the ore body depth,the distribution of the LREEs decreased and the HREEs increased.And the slight differences in the adsorption ability of REEs on clay minerals led to the fractionation effect in the column leaching process.These developed more evidences and better understanding of metallogenic regularity,and provided a theoretical basis and scientific approach to separation of the HREEs and LREEs in the leaching process.     

Effects of Ni on austenite stability and fracture toughness in high Co-Ni secondary hardening steel

Three kinds of high Co-Ni secondary hardening steels with different Ni contents were studied.The nanoscale austenite layers formed at the interface of matensite laths were observed.Both observation and diffusion kinetic simulation results showed that both Ni and Co did not obtain enough time to get the equilibrium content in this system.The Ni content in austenite layers decreased significantly,and Co content increased slightly with the decrease of Ni content in overall composition.The austenite stability was estimated by Olson-Cohen model,in which both chemical and mechanical driving force could be calculated by equilibrium thermodynamic and Mohr′s circle methods,respectively.Simulation and mechanical test results showed that the decrease of Ni content in austenite layers would cause the change of austenite stability and decrease the fracture toughness of the steels.When the Ni content in the overall composition was lower than 7wt.%,the Ni content inγphase would be lower than 20 wt.%.And the simulation value of Mσs(stress-induced critical martensite transformation temperature)would be up to 80°C,which was about 60°C higher than room temperature.Based on the analysis,the Ni content in the overall composition of high Co-Ni secondary hardening steels should be higher than 8wt.% in order to obtain a good fracture toughness.     

Sediment provenance discrimination in northern Okinawa Trough during the last 24 ka and paleoenvironmental implication:rare earth elements evidence

Rare earth elements(REE) compositions and discriminant function were successfully used to examine high resolution sediment source changes in the northern Okinawa Trough over the last 24.1 ka,especially for the influence from the Yellow River and the Tsushima Warm Current(TWC) that has not been well solved.Variations of these parameters were clearly divided into three distinct depositional units.During Interval 1(24.1-16.0 ka BP),the paleo-Yellow River and the paleo-Yangtze River mouths were situated near the studied area and could have played major roles in the sedimentation therein.In Interval 2(16.0-7.3 ka BP),these river mouths gradually retreated with global sea-level rise,leading to less fluvial inputs from them to the northern Okinawa Trough.Meanwhile,formation of the TWC could carry some sediment loads of Taiwan to the studied core,especially during its late phase(8.0-7.3 ka BP).Modern oceanographic conditions,with a predominance of the TWC,were finally established since the beginning of Interval 3,causing more terrigenous contribution from Taiwan to the studied area.Sub-sequently,modern depositional environments mainly influenced by the Yellow River,the Yangtze River,and the TWC were finally formed.     

Thermodynamic description of Sn-Y and Mg-Sn-Y systems

The thermodynamic optimization of the Sn-Y and Mg-Sn-Y systems was critically carried out by means of the CALPHAD（CALculation of PHAse Diagram） technique. In the Sn-Y system, the solution phases（liquid, bcc, bct and hcp） were described by the substitutional solution model. The compound Sn3Y5, which has a homogeneity range, was treated as the formula（Sn, Y）3（Sn, Y）2Y3 by a three-sublattice model in accordance with the site occupancies. In the Mg-Sn-Y system, the liquid phase was treated as the formula（Mg, Sn, Y, Mg2Sn） using an associated solution model, and bcc, bct and hcp were treated as the formula（Mg, Sn, Y）. The compound Sn3Y5 was treated as the formula（Sn, Y, Mg）3（Sn, Y, Mg）2Y3. The ternary compound MgSnY was treated as stoichiometric compound. A set of self-consistent thermodynamic parameters of the Mg-Sn-Y system was obtained. The projection of the liquidus surfaces and the reaction scheme of the Mg-Sn-Y system were predicted.     

Critical parameters near the ferromagnetic-paramagnetic phase transition in La0.67–xYxBa0.23Ca0.1MnO3 compounds（x=0.10 and x=0.15）

The critical properties of the mixed manganite La0.67–x Y x Ba0.23Ca0.1Mn O3 with x=0.10 and x=0.15 around the paramagnetic(PM)-ferromagnetic(FM) phase transition were investigated through various techniques. These involved modified Arrott plots, Kouvel-Fisher method and Widom scaling relation. Magnetic data, analyzed in the critical region, using the above methods, yielded the critical exponents for(x=0.10) La0.57Y0.10Ba0.23Ca0.1Mn O3(β=0.312±0.002 and γ=1.147±0.003 at T C=299.23±0.05 K). Moreover, the estimated critical exponents of(x=0.15) La0.52Y0.15Ba0.23Ca0.1Mn O3 were β=0.286±0.004 and γ=0.943±0.002 at T C=289.53±0.06 K. The critical exponents’ values were close to the theoretical values of 3D-Ising model and tricritical mean-field model. These results suggested that the present composition should be close to a tricritical point in the La0.67–x Y x Ba0.23Ca0.1Mn O3 phase diagram. Expressing the field dependence as ΔS M∝H n allowed us to establish a relationship between the exponent n and the critical exponents of the material and to propose a phenomenological universal curve for the field dependence of ΔS M.     

Numerical simulation of tube profile growth during spray forming process

Spray forming is a new type of metal material forming process,which can produce metal blanks such as billet,tube,plate etc.A mathematical model has been developed to forecast the shape evolution of tube billets during the spray forming process.The atomizer mass flux as,radial distribution coefficient bs,draw velocity and diameter of mandrel were considered in this model and the influence of different parameters such as metal flowrate,draw velocity of mandrel,diameter of mandrel on the tube’s shape change were simulated and analyzed in this paper.The simulation results obtained from this model can be provided to engineers as reference.     

Application of Adaptive Threading Technique to Hot Strip Mill

Thickness deviation of hot strip rolling needs to be strictly controlled in the computer system. An adaptive threading technique was researched, in which the measured data from threaded stands were used to predict thickness and material hardness errors, to modify the setup for the remaining unthreaded stands. After the adaptive threading model was used online on the hot strip mill of the Panzhihua Iron and Steel Group Co Ltd, the thickness deviation was decreased obviously. The hit rate of thickness control of different steel grades increases.