scholarly journals Rare Earth Elements: Their Importance in Understanding Soil Genesis

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Michael T. Aide ◽  
Christine Aide
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Water Adsorption ◽  
Oxidation States ◽  
Trace Minerals ◽  
Chemical Affinity ◽  
Ionic Radii ◽  
Near Surface ◽  
Lanthanide Series ◽  
Migration Pathways

The rare earth elements (REEs) are commonly defined as lanthanum (La) and the 14 elements comprising the Lanthanide series. The REE’s typically exhibit trivalent oxidation states; however, Europium may also occur as Eu2+ and Cerium may occur as Ce4+. The REE’s ionic radii decrease on progression from La to Lu, which results in a slight but predictable change in their chemical affinity. Typically, the light REE (La to Sm) reside in trace minerals such as apatite, epidote and allanite, whereas the heavy REE (Gd to Lu) are associated with minerals such as zircon. Investigations typically show that the REE are depleted in near-surface horizons and accumulate in deeper horizons or the regolith as clay-oxyhydroxide adsorbates or REE-phosphate precipitates. Numerous studies show the heavy REE accumulating in the deeper soil regions to a greater extent than the light REE, whereas other studies show the light REE’s preferentially accumulating at greater soil depths. The degree of interhorizon transport has great potential to become an index of weather intensity. The various REE soil migration pathways have been isolated, including lessivage, soil organic matter complexation, leaching in percolating water, adsorption by inorganic colloids, and precipitated by phosphate-bearing minerals.

Rare earth elements tracing interrill erosion processes as affected by near-surface hydraulic gradients

2020 ◽  
Vol 202 ◽  
pp. 104673 ◽  
Author(s):  
Chenfeng Wang ◽  
Bin Wang ◽  
Yujie Wang ◽  
Yunqi Wang ◽  
Wenlong Zhang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Near Surface ◽  
Erosion Processes ◽  
Hydraulic Gradients ◽  
Interrill Erosion

Oxides of rare-earth elements in lower oxidation states

1986 ◽  
Vol 35 (9) ◽  
pp. 1778-1780
Author(s):  
K. I. Slovetskaya ◽  
Yu. S. Khodakov ◽  
A. M. Rubinshtein ◽  
Kh. M. Minachev
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Oxidation States ◽  
Lower Oxidation

scholarly journals Geochemical Characterization and Presence of Rare Earth Elements in the Recent Depositions at the Islands of the Eastern Bay of Bengal, Bangladesh

2020 ◽  
Vol 11 (1) ◽  
pp. 40-47
Author(s):  
Farah Deeba ◽  
Syed Hafizur Rahman ◽  
Mohammad Zafrul Kabir ◽  
Mohammad Rajib
Keyword(s):  
Rare Earth ◽  
Chemical Composition ◽  
Rare Earth Elements ◽  
Bay Of Bengal ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Mineral Concentration ◽  
Near Surface ◽  
Geochemical Characterization ◽  
X Ray

This study presents geochemical characterization, as well as, quantification of rare earth elements in the recent beach deposition at the two major islands of the eastern Bay of Bengal-Kutubdia and Moheshkhali. Placer sand samples from near surface depositions were analyzed by heavy mineral separation, mineralogical identification, chemical composition and elemental mapping. X-ray diffraction (XRD), X-ray fluorescence (XRF), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) were used to obtain these results. The heavy mineral concentration in different raw sand samples resulted by heavy liquid separation technique revealed that the average abundance of heavy minerals is 69.67% in Kutubdia island and 9.32% in Moheshkhali island, respectively. The X-ray patterns of Kutubdia and Moheshkhali sand samples show the presence of zircon, quartz, hematite, magnetite, ilmenite, chromite, kyanite, anatase, rutile and garnet. Chemical composition of heavy mineral sands from Kutubdia and Moheshkhali islands were analyzed using X-ray fluorescence method (XRF) for major oxides and trace elements. The concentration is of Na2O, MgO, Al2O3, SiO2, P, K2O, CaO, TiO2, V2O5, Cr2O3, MnO, Fe2O3, CoO, ZnO, SrO, Y2O3 ZrO2, Nb2O5, MoO3, HfO2, WO3, ThO2, U3O8, CeO2, Nd2O and Er2O3 were determined. A significant amount of various rare earth elements (REEs) in the elemental composition of few samples was also identified. The study is expected to be useful in the baseline and environmental aspects of both the islands.

scholarly journals Ecotoxicity Responses of the Macrophyte Algae Nitellopsis obtusa and Freshwater Crustacean Thamnocephalus platyurus to 12 Rare Earth Elements

2020 ◽  
Vol 12 (17) ◽  
pp. 7130
Author(s):  
Levonas Manusadžianas ◽  
Rimantas Vitkus ◽  
Brigita Gylytė ◽  
Reda Cimmperman ◽  
Mindaugas Džiugelis ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Chemical Properties ◽  
Nitellopsis Obtusa ◽  
Ionic Radii ◽  
Eu Directive ◽  
Thamnocephalus Platyurus ◽  
Median Lethal Concentrations ◽  
Freshwater Crustacean ◽  
Ree Group

Due to unique chemical properties, rare earth elements (REEs) are increasingly used in versatile technological applications. They are considered emerging environmental contaminants, since they become mobile instead of being bound in rocks. At present, the information on REE effects to aquatic biota is scarce and contradictory. This study aims to explore the ecotoxicity of 11 lanthanides (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, and Lu) and yttrium (Y) to charophyte algae Nitellopsis obtusa and microcrustaceans Thamnocephalus platyurus. Median lethal concentrations (LC50) were assessed in characean cells at 8, 12, 16, 20, and 24 days of exposure, and 24-h LC50s were determined in shrimps. According to the EU−Directive 93/67/EEC hazard classification scheme and 24-day LC50 values generated for N. obtusa, REE effects were assigned from “harmful” to “very toxic” (Gd), while 24-h LC50s for T. platyurus were classified as “harmful” or “toxic” (based on nominal concentrations) and as “toxic” or “very toxic” (based on REE free ion concentrations calculated with CHEAQS Next software). The data obtained for algae showed correlations with the REE atomic numbers (r = −0.68, p < 0.05) and ionic radii (r = 0.65, p < 0.05) at the most extended 24-day exposure only. The analysis of the trends of concentration−response (c–r) curves obtained at increasing exposure durations (8–24 days), alongside the 24-day LC50s ranging within almost two orders of magnitude, allowed a more-toxic heavy REE group to be distinguished, and somewhat different modes REE actions to be envisioned for N. obtusa.

Problems in electron microprobe analysis of the lanthanides: The x-ray lines

1990 ◽  
Vol 48 (2) ◽  
pp. 200-201
Author(s):  
P. F. Hlava
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Atomic Number ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Chemical Behavior ◽  
X Ray ◽  
Lanthanide Series ◽  
Valence Electrons

Electron microprobe analysis of materials that contain the lanthanide series of rare earth elements (REE) in natural abundance ratios presents a difficult and truly unique set of problems due to the their chemical and crystallographic similarity and the complexity of the L-spectra used for analysis. REEs differ from one another by the number of protons in their nuclei and the number of electrons in their second inner shell. There are two series of REEs - the lanthanides, from atomic number 58 through 71 and the actinides from 90 through 103. By convention, when most workers speak of the REEs they refer to the lanthanides plus lanthanum, often yttrium and rarely scandium (because these elements are geochemically associated with the lanthanides proper). The terms REE and lanthanide, when used in this paper, will refer to elements of atomic number 57 through 71. In all of these elements the two outer shells, where the valence electrons reside, are essentially identical resulting in chemical behavior that is also essentially identical.

scholarly journals Separation of Rare Earth Elements (REE) by Ion Interaction Chromatography (IIC) Using Diglycolic Acid (ODA) as a Complexing Agent

2021 ◽  
Vol 84 (5) ◽  
pp. 473-482
Author(s):  
Rajmund S. Dybczyński ◽  
Krzysztof Kulisa
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Atomic Number ◽  
Mobile Phase ◽  
Low Ph ◽  
Complexing Agent ◽  
Diglycolic Acid ◽  
Lanthanide Series ◽  
Light Lanthanides ◽  
Ree Group

AbstractThe possibility of rare earth elements (REE) separation by ion interaction chromatography (IIC) employing their complexes with diglycolic acid (ODA) in anion exchange mode has been studied theoretically and experimentally. Calculations, assuming that only trivalent complex is significantly uptaken by the stationary phase, indicated that at at pH 4–6, the retention in the lanthanide series should increase from La to the Tb–Dy–Ho region with yttrium showing apparent atomic number (App.At.No.) of 67½ and then decrease with further increase of atomic number. Chromatographic experiments in the system: Column: Eternity C18—mobile phase 5 mM ODA/8.6 mM TBAOH/0.6 mM HNO3; pH 4.60 confirmed theoretically predictions. It was found that scandium at pH ≥ 4.0 elutes in front of the whole REE group but at low pH enters the region of light lanthanides. The non-monotonical change of affinity of the REE with the increase of atomic number results in quite unusual order of elution of REE namely: Sc < La < Ce < Lu < Pr < Yb < Nd < Tm < Sm < Eu < Er≈Y < Gd < Ho < Tb≈Dy.

scholarly journals Geochemical Characterization and Presence of Rare Earth Elements in the Recent Depositions at the Islands of the Eastern Bay of Bengal, Bangladesh

2020 ◽  
Vol 11 (1) ◽  
pp. 40-47
Author(s):  
Farah Deeba ◽  
Syed Hafizur Rahman ◽  
Mohammad Zafrul Kabir ◽  
Mohammad Rajib
Keyword(s):  
Rare Earth ◽  
Chemical Composition ◽  
Rare Earth Elements ◽  
Bay Of Bengal ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Mineral Concentration ◽  
Near Surface ◽  
Geochemical Characterization ◽  
X Ray

This study presents geochemical characterization, as well as, quantification of rare earth elements in the recent beach deposition at the two major islands of the eastern Bay of Bengal-Kutubdia and Moheshkhali. Placer sand samples from near surface depositions were analyzed by heavy mineral separation, mineralogical identification, chemical composition and elemental mapping. X-ray diffraction (XRD), X-ray fluorescence (XRF), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) were used to obtain these results. The heavy mineral concentration in different raw sand samples resulted by heavy liquid separation technique revealed that the average abundance of heavy minerals is 69.67% in Kutubdia island and 9.32% in Moheshkhali island, respectively. The X-ray patterns of Kutubdia and Moheshkhali sand samples show the presence of zircon, quartz, hematite, magnetite, ilmenite, chromite, kyanite, anatase, rutile and garnet. Chemical composition of heavy mineral sands from Kutubdia and Moheshkhali islands were analyzed using X-ray fluorescence method (XRF) for major oxides and trace elements. The concentration is of Na2O, MgO, Al2O3, SiO2, P, K2O, CaO, TiO2, V2O5, Cr2O3, MnO, Fe2O3, CoO, ZnO, SrO, Y2O3 ZrO2, Nb2O5, MoO3, HfO2, WO3, ThO2, U3O8, CeO2, Nd2O and Er2O3 were determined. A significant amount of various rare earth elements (REEs) in the elemental composition of few samples was also identified. The study is expected to be useful in the baseline and environmental aspects of both the islands.

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