Geochemical Characteristics of Rare Earth Elements in Sewage Discharge Channels of Tianjin

The geochemical features of rare earth elements (REEs) in the North and South sewage discharge channels of Tianjin were studied. The results show that concentrations of dissolved REEs in water of the sewage discharge channels are very low, while concentrations of Eu and heavy REEs are higher than those in natural rivers. Concentrations of REEs in unfiltered water are high and they mainly resided on suspended matter. Distribution patterns of the dissolved and suspended light REEs vary reversely with the atomic number. Concentrations of REEs in the sediments and suspended matter are lower than those in natural rivers, and concentrations of REEs in the suspended matter are much lower than those in the sediments. Distrib.ution patterns of REEs in sediments and suspended matter were similar with light REE enrichment and positive Eu-anomaly. This distribution pattern is different from those of natural rivers. The differences may cause by the large amount of organic pollutants in sewage.     

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.     

Geochemical Characteristics of Rare Earth Elements in Different Types of Soils in China

ＧｅｏｃｈｅｍｉｃａｌＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＲａｒｅＥａｒｔｈＥｌｅｍｅｎｔｓｉｎＤｉｆｅｒｅｎｔＴｙｐｅｓｏｆＳｏｉｌｓｉｎＣｈｉｎａＷａｎｇＬｉｊｕｎ（王立军），ＺｈａｎｇＳｈｅｎ（章申），ＧａｏＸｉａｏｊｉａｎｇ（高效江），Ｌｉｕ...     

不同降雨条件下城市路尘中稀土元素流失特征

通过对包头市路尘中14种稀土元素(rare earth elements,REEs)含量的测定分析以及小型人工降雨冲刷模拟,对稀土元素在路尘中的赋存特征及在其降雨径流中的流失特征进行了分析和探讨。结果表明,(1)路尘中的稀土元素随降雨过程发生迁移并在径流产生"流失浓缩"效应,浓缩强度随雨强增加而增强;相同雨强下,水泥下垫面的聚集效应高于沥青混凝土下垫面。(2)径流中水相稀土元素含量随降雨时间下降。(3)径流流失过程中,固相颗粒态中稀土元素的配分模式与路尘样品基本一致,呈现轻稀土富集的特征,轻重稀土之间的分馏程度较高;而水相中稀土元素的配分模式与原始路尘样品中有一定差异,轻重稀土之间的分馏程度降低。     

Accumulation and Fractionation of Rare Earth Elements in Soil-Rice Systems

Rare earth elements(REEs)have been widelyapplied in agriculture as micro-fertilizer in China,andit has become an urgent taskto understand their cont-ents,distribution,translocation and accumulation inthe soil-crop systems and their ecological effects,inor…     

A preliminary reassessment of δEu_N-ΣREEs plot for distinguishing sediment provenances

Several REE data sets were collected in Core DD2 and EC2005 in the inner shelf of East China Sea,Core Y127 in the northern Okinawa Trough,Core NT1,C9247 and C92169 in the south Yellow Sea to check the applicability of the δEuN-ΣREEs model for quantita-tively distinguishing sediments from the Yangtze River and the Yellow River.By comparison,several sediments in cores DD2,EC2005,Y127 are generally in accordance with this model.The cores NT1,C9247 and C92169,which have been influenced by the Yangtze River and the Yellow River together,however,were inconsistent with the δEuN-ΣREEs model.The δEuN-ΣREEs plot and its corresponding regression equation,which could be used to distinguish sediments "intuitively and quantitatively" from the Yangtze River,and the Yellow River should be reconsidered or reassessed.     

Comparative study on rare earth elements from Flos Sophorae and Fructus Sophorae

Flos Sophorae and Fructus Sophorae are two kinds of traditional Chinese medicines. In this work, the two kinds of traditional Chi-nese medicines collected from eleven areas of Dezhou, were analyzed by inductively couple plasma-mass spectrometry (ICP-MS) to compare the content and distribution of 14 kinds of rare earth elements (REEs). The method was verified by analyzing GBW07605 certified reference material. The results showed that ICP-MS is an accurate, sensitive and reliable technique for determining REEs in traditional Chinese medi-cine. There were big differences in contents for REEs in Flos Sophorae and Fructus Sophorae from different areas. The contents of total REEs in Flos Sophorae samples from different areas ranged from 1.0785 to 2.2659 g/g, while those in Fructus Sophorae from 0.6826 to 1.0527 g/g. The contents of total REEs in Flos Sophorae samples from different areas were obviously higher than those in Fructus Sophorae of the same area and there was big difference between various Flos Sophorae samples. Interestingly, the higher the content of total REEs in Flos Sophorae samples, the lower the content of total REEs in Fructus Sophorae samples of the same area. The plots of normalized element con-centration versus atomic number showed some characteristic distribution trends. The distribution trend of light REEs (La-Gd) was relatively flat except a positive Eu anomaly, however, that was steep and discrepant for heavy REEs (Tb-Lu). The results could provide a valuable ref-erence for understanding the relationship between the curative mechanism, pharmacology characteristics and their geological condition for the two traditional Chinese medicines investigated.     

Study on REEs as tracers for late permian coal measures in Bijie City, Guizhou Province, China

Analyses of Rare Earth Elements （REEs） in 13 coal samples collected from Late Permian coal measures of Bijie City in western Guizhou Province were conducted using Inductively Coupled Plasma-Mass-Spectrometry （ICP-MS）. The results indicated that REEs patterns were not controlled by materials from the sea, whereas the contribution of land plants was about 1%. The major sources of REEs were from terrigenous material as indicated by negative Eu anomaly. There were similar distribution curves of REEs between Bijie＇s coal and Emeishan basalt. M12 coal seam, which had the highest ∑REE, appeared near the boundary between Longtan Formation and Changxing Formation, which was closely correlated to the eruption of Emeishan basalt. The Emeishan basalt contributed to REEs enrichment of M12. So the sources of REEs were controlled by terrigenous material, and the Emeishan basalt was the predominant source of terrigenous material, which dominated the enrichment and pattern of REEs in Late Permian coal measure from Bijie.     

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.     

Geochemistry of rare earth elements in cobalt-rich crusts from the Mid-Pacific M seamount

Rare earth elements (REEs) and major elements of 25 cobalt-rich crusts obtained from different depths of Mid-Pacific M seamount were analyzed using inductively coupled plasma-atomic emission spectrometer and gravimetric method. The results showed that they were hydrogenous crusts with average ∑REE content of 2084.69 μg/g and the light REE (LREE)/heavy REE (HREE) ratio of 4.84. The shale-normalized REE patterns showed positive Ce anomalies. The total content of strictly trivalent REEs increased with water depth. The Ce content and LREE/HREE ratios in Fe-Mn crusts above 2000 m were lower than those below 2000 m. The change in REE with water depth could be explained by two processes: adsorptive scavenging by setting matters and behaviors of REE in seawater. However, the Ce abundance took no obvious correlation with water depth reflects the constant Ce flux. The Ce in crusts existed mainly as Ce(IV), implying that the oxidative-enriching process was controlled by kinetic factors.     

Study on Adsorption of Rare Earth Elements by Kaolinite

Rareearthelements (REEs)werewidelyappliedtotracingthesourcesofmaterialsandtostudyingtheirevolutionprocessesinmanyfieldsofearthscienceinconsiderationoftheirsimilarityandsystematicdiffer enceinchemicalproperties .Furthermore ,lanthanidesarebothimportantprod…     

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 ...     

Fractionation of Rare Earth Elements in Plants Ⅰ. Fractionation Patterns and Their Forming Mechanisms in Different Organs of Triticum Aestivum

Fractionations of rare earth elements (REEs) and the forming mechanisms in plants were studied using Triticum aestivum as plant material with application of exogenous REEs and hydroponic culture. REEs were significantly fractionated in different parts of Triticum aestivum. M-type tetrad effect could be observed in both root and shoot of Triticum aestivum, which might result from the different abilities of REEs to form phosphate precipitation. Middle REEs (MREEs), light REEs (LREEs) and heavy REEs (HREEs) were enriched in root, stem and leaf of Triticum aestivum, respectively. REE speciation calculations using VMINTEQ program show REEs in simulated xylem solution mainly exist as REE-EDTA- and RE3 , but only HREEs are enriched in REE-EDTA-, while LREEs are enriched in the other REE species. It is suggested that the fractionation between LREEs and HREEs might be caused by the uptake of REE-EDTA- in Triticum aestivum leaves, but might result from the uptake of the other REE species in their stems.     

Distribution of rare earth elements in sewage-irrigated soil profiles in Tianjin, China

The concentrations of rare earth elements(REEs)in the soil extracts and soil solutions from two different alluvial soil profiles irrigated with sewage were measured using inductively coupled plasma-mass spectrometry.The results showed that the REE concentrations in the soil extracts from soil samples affected by sewage irrigation were much higher than those in virgin soil samples.The REE concentrations in the soil extracts of the rhizophere soil were higher than those of the non-rhizophere soil.The shale-normalized REE patterns in the soil extracts from the upper soil layer affected by sewage irrigation shown middle REE(MREE)enrichment relative to light REE(LREE)and heavy REE(HREE).This result was attributed to the MREE-rich organic colloidal material,REE-HM(humic and fulvic acids)and phosphate-REE complexations.The REE patterns in the soil extracts from deep soil little-affected by sewage irrigation showed HREE enrichment relative to LREE,which might have been caused by the preferential complexation of HREE with carbonate.The normalized La/Yb ratios in the soil extracts increased with the decrease in depth.The sewage irrigation did not affect the total REE contents and REE pattern in the soil profiles.     

Fractionation of Rare Earth Elements in Plants Ⅰ. Fractionation Patterns and Their Forming Mechanisms in Different Organs of Triticum Aestivum

Rareearthelements(REEs)havetworemarka blecharacteristics:firstly,REEshaveverysimilar chemicalbehaviorsthatimpartcoherencyingeo chemicalprocesses;secondly,slightbutsystemic differencesofchemicalbehaviorsexistamongthem andtheytendtofractionateinsomenatura…     

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.     

Enrichment process of lanthanum as a nonessential trace element in leaf cells of lettuce (Lactuca sativa L.)

Rare earth elements (REEs) as nonessential trace elements are enriched in living organisms and threaten their health. To early detect and reduce REE enrichment in living organisms, scientists are focused on clarifying the enrichment process of REEs in living organisms and its risks. However, the enrichment process of REEs in edible plant cells has remained unclear. Herein, by using interdisciplinary methods and techniques, the enrichment process of lanthanum (La(III)) in the leaf cells of lettuce (Lactuca sativa L.) was investigated. (1) When La(III) exposure dose is 0.5–5 μmol/L, La(III) is enriched outside the plasma membrane (PM). In this zone, La(III) is bound to vitronectin-like protein (VN) to form La–VN complexes; (2) When La(III) exposure dose is 5–20 μmol/L, besides the zone outside the PM, La(III) is also enriched on the PM and bound to arabinogalactan proteins (AGPs) to form La–AGPs complexes; (3) When La(III) exposure dose is 20–140 μmol/L, besides the zone outside and on the PM, La(III) is enriched inside the PM; (4) When La(III) exposure dose is 60–140 μmol/L, malondialdehyde content (an important indicator of invisible damage) significantly increases. Thus, as La(III) exposure dose increases, La(III) gradually migrates from outside the PM to the PM and inside the PM, enriching in these zones in turn. The enriched La(III) will cause invisible damage to lettuce leaf cells and even enter human bodies along food chains. These results provide references for investigating the enrichment process of REEs in plants and its environmental risks, and finding strategies to early detect and reduce REE enrichment in plants.     

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.     

Extraction of selected rare earth elements from anthracite acid mine drainage using supercritical CO_2 via coagulation and complexation

Rare earth elements(REEs) are valuable raw materials which are in great demand in modern high technology industries.Developing methods to produce/recover REEs from waste is significant to the national security of any developed country.This study was focused on investigating the use of supercritical CO2(sCO_2) to extract REEs from anthracite acid mine drainage(AMD).Four different mine drainage water source locations at Blaschak Coal Corp.in Pennsylvania,USA were selected for sample collection.An extraction process was developed and demonstrated for two of those water sources containing the highest concentration of REEs.A method involving metal ion coagulation,their dissolution from the sludge into a concentrated aqueous HNO_3 solution,complexation with organic ligands and sCO_2 extraction was developed to recover REEs from AMD.Specifically,sodium aluminate(NaAlO_2) was used as the coagulant to concentrate REEs from the AMD into a solid precipitate.Consequently,over 99%of the REEs in AMD is concentrated in the remaining sludge.During the coagulation process,the effects of pH and NaAlO_2 concentration on REE precipitation were investigated.Fuming nitric acid(HNO_3) was used to digest the pre-concentrated sludge and tributyl phosphate(TBP) was used to form REE/TBP/HNO_3,a non-polar complex with selected REEs,specifically,cerium(Ce),lanthanum(La) and neodymium(Nd).HNO_3 concentration and organic/aqueous phase ratio were considered as the variables to improve complexation efficiency.Dynamic extraction experiments using sCO_2 and REE/TBP/HNO_3 solutions were then conducted at optimal conditions of 60℃ and 20 MPa.The overall REE extraction efficiencies are found to increase with the atomic number of the REE.As a result,the average overall REE extraction efficiencies of 41.8%,40.1% and 58.2% for Ce,La and Nd,respectively,are obtained.The potential improvements in the overall extraction efficiency are also discussed.     

Extraction of rare earth elements from a South American ionic clay

Ionic clays,formed by the natural weathering of REE-bearing minerals and the adsorption of the resulting liberated REE ions onto the clay surface,are an important resource for critical rare earth elements(REEs).Here,a two-step desorption process using ammonium sulfate with active pH adjustment using sulfuric acid was developed to extract REEs from a South American clay.The desorption process was optimized using response surface methodology approach and the optimum operating conditions were deter...