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Sample records for earth element fractionation

  1. Bishop tuff revisited: new rare Earth element data consistent with crystal fractionation.

    PubMed

    Cameron, K L

    1984-06-22

    The Bishop Tuff of eastern California is the type example of a high-silica rhyolite that, according to Hildreth, supposedly evolved by liquid-state differentiation. New analyses establish that the Bishop Tuff "earlyllate" rare earth element trend reported by Hildreth mimics the relations between groundmass glasses and whole rocks for allanite-bearing pumice. Differences in elemental concentrations between whole rock and groundmass are the result of phenocryst precipitation; thus the data of Hildreth are precisely those expected to result from crystal fractionation. PMID:17837193

  2. Bioavailable concentrations of germanium and rare earth elements in soil fractions

    NASA Astrophysics Data System (ADS)

    Hentschel, Werner; Wiche, Oliver

    2015-04-01

    As there is an increasing demand for germanium and the rare earth elements due to their diverse application in modern technologies (optical cables, permanent magnets in wind power stations), there is an interest to investigate a new approach to extract these ubiquitous but disperse existing elements - via Phytomining. But before this method can be established, a thorough understanding of processes regarding the intake of germanium (Ge) and the rare earth elements (REEs) is necessary. The aim of this work was to get insights or hints on correlations between the concentrations and the fractionation of Ge and REEs in the soil and the concentrations in plants - in other words we wanted to conduct research on bioavailable concentrations of Ge and REEs in soil fractions. On 18 sites situated around Freiberg, Saxony we took samples of soil and plants. To extract the elements from the plant material a decomposition with hydrofluoric acid was used. The soil samples was examined by a sequential extraction with seven steps (mobile, carbonatic, oxidisable, amorphic oxides, crystalline oxides, phytoliths and secondary clay minerals, residual or siliceous). The amounts of the REEs showed a high correlation between each other, so neodymium can be regarded as a proxy for all REEs. The average total amount of Ge in the soil samples was around 1.45 mg/kg, the one of neodymium (Nd) was around 25 mg/kg. Both values equal the overall average in the earth crust. Concerning the Ge concentration in soil the residual siliceous fractions constituted for 70% of total, whereas the fractions V and VI - dedicated as crystalline oxides and phytoliths/secondary clay minerals - made out for 25%. Only 5% of the total amount of Ge in soil accounted for the fractions I to IV. There was found a statistical significant correlation between the absolute Ge concentrations in these latter soil fractions with the Ge concentration in plant material of the same site. Therefore it seems that the fractions I to IV could be regarded as a proxy for the bioavailable pool of Ge in soils. Concerning Nd the residual siliceous fractions made out for 60% of the total, whereas the fraction III (oxidisable) constitutes for 30%. The remaining 10% accounted for the other soil fractions. No correlation between the concentration in one soil fraction and the concentration in plant material from the same site could be found. There was also no correlation between the total amount in soil and the concentration in plant material from the same site neither for the REEs nor for Ge. These results can give only hints on the processes regarding the mobilisation of the bioavailable pool of Ge and REEs. Further investigations are necessary and will be taken in the PhytoGerm project.

  3. Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China.

    PubMed

    Wang, Lingqing; Liang, Tao

    2015-01-01

    Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China's largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65?×?10(4)?mg·kg(-1) with an average value of 4.67?×?10(3)?mg·kg(-1), which was significantly higher than the average value in China (181?mg·kg(-1)). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N) and Gd(N)/Yb(N)). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind. PMID:26198417

  4. Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China

    NASA Astrophysics Data System (ADS)

    Wang, Lingqing; Liang, Tao

    2015-07-01

    Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China’s largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65?×?104?mg·kg-1 with an average value of 4.67?×?103?mg·kg-1, which was significantly higher than the average value in China (181?mg·kg-1). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (LaN/YbN, LaN/SmN and GdN/YbN). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind.

  5. Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China

    PubMed Central

    Wang, Lingqing; Liang, Tao

    2015-01-01

    Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China’s largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65?×?104?mg·kg?1 with an average value of 4.67?×?103?mg·kg?1, which was significantly higher than the average value in China (181?mg·kg?1). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (LaN/YbN, LaN/SmN and GdN/YbN). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind. PMID:26198417

  6. Fractionation in the solar nebula - Condensation of yttrium and the rare earth elements

    NASA Technical Reports Server (NTRS)

    Boynton, W. V.

    1975-01-01

    The condensation of Y and the rare earth elements (REE) from the solar nebula may be controlled by thermodynamic equilibrium between gas and condensed solids. Highly fractionated REE patterns may result if condensates are removed from the gas before condensation is complete. It is found that the fractionation is not a smooth function of REE ionic radius but varies in an extremely irregular pattern. Both Yb and Eu are predicted to be extremely depleted in the early condensate without the requirement of condensation in the divalent state. The model is discussed with respect to a highly fractionated pattern observed by Tanaka and Masuda (1973), in a pink Ca-Al-rich inclusion from the Allende meteorite and can account for the abundances of each REE determined. According to the model this inclusion represents a condensate from a previously fractionated gas rather than from a gas of solar composition. Before the condensation of this inclusion, an earlier condensate was formed and was removed from equilibrium with the gas.

  7. Efficient mobilization and fractionation of rare-earth elements by aqueous fluids upon slab dehydration

    NASA Astrophysics Data System (ADS)

    Tsay, A.; Zajacz, Z.; Sanchez-Valle, C.

    2014-07-01

    The characteristic REE fractionation pattern in arc magmas compared to MOR-basalts results from the selective mobilization of light rare-earth elements (LREE) by slab-derived mobile components. However, the nature and composition of the slab flux, and the actual mechanisms responsible for the transfer of rare-earth elements (REE) from the slab to the mantle wedge remain unclear. We present experimental data on the solubility of selected REE in ligand-bearing aqueous fluids and a hydrous haplogranitic melt at 2.6 GPa and 600-800 °C, spanning the conditions relevant to slab dehydration and melting. The solubilities of REE in aqueous fluids increase more than an order of magnitude with temperature increasing from 600 to 800 °C. Addition of ligands such as Cl-, F-, CO32-, SO42- in relatively small concentrations (0.3-1.5 m [mol/kg H2O]) has a pronounced effect further enhancing REE solubilities. Each ligand yields a characteristic REE pattern by preferential dissolution of either the light or the heavy REE. For example, the addition of NaCl to the aqueous fluids yields highly elevated LREE/HREE ratios (La/Yb=17.4±4.3), whereas the addition of fluoride and sulfate ligands significantly increases the solubility of all REE with moderate LREE/HREE fractionation (La/Yb?4). The addition of Na2CO3 results in preferential increase of HREE solubilities, and yields La/Yb ratio of 1.6±0.5 by flattening the moderately fractionated REE pattern seen in pure aqueous fluids. The solubilities in hydrous haplogranite melt are moderate in comparison to those observed in aqueous fluids and do not lead to pronounced REE fractionation. Therefore, REE can be effectively mobilized and fractionated by aqueous fluids, compared to felsic hydrous melts. Furthermore, the aqueous fluid chemistry has a major role in determining REE mobilities and fractionation upon slab dehydration in addition to the significant control exerted by temperature. Our results show that chloride-bearing slab-derived aqueous fluids have a significant contribution to the formation of REE-signatures in arc-magmas, especially at lower slab surface temperatures.

  8. Thulium anomalies and rare earth element patterns in meteorites and Earth: Nebular fractionation and the nugget effect

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Pourmand, Ali

    2015-08-01

    This study reports the bulk rare earth element (REEs, La-Lu) compositions of 41 chondrites, including 32 falls and 9 finds from carbonaceous (CI, CM, CO and CV), enstatite (EH and EL) and ordinary (H, L and LL) groups, as well as 2 enstatite achondrites (aubrite). The measurements were done in dynamic mode using multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS), allowing precise quantification of mono-isotopic REEs (Pr, Tb, Ho and Tm). The CI-chondrite-normalized REE patterns (LaN/LuN; a proxy for fractionation of light vs. heavy REEs) and Eu anomalies in ordinary and enstatite chondrites show more scatter in more metamorphosed (petrologic types 4-6) than in unequilibrated (types 1-3) chondrites. This is due to parent-body redistribution of the REEs in various carrier phases during metamorphism. A model is presented that predicts the dispersion of elemental and isotopic ratios due to the nugget effect when the analyzed sample mass is limited and elements are concentrated in minor grains. The dispersion in REE patterns of equilibrated ordinary chondrites is reproduced well by this model, considering that REEs are concentrated in 200 ?m-size phosphates, which have high LaN/LuN ratios and negative Eu anomalies. Terrestrial rocks and samples from ordinary and enstatite chondrites display negative Tm anomalies of ?-4.5% relative to CI chondrites. In contrast, CM, CO and CV (except Allende) show no significant Tm anomalies. Allende CV chondrite shows large excess Tm (?+10%). These anomalies are similar to those found in group II refractory inclusions in meteorites but of much smaller magnitude. The presence of Tm anomalies in meteorites and terrestrial rocks suggests that either (i) the material in the inner part of the solar system was formed from a gas reservoir that had been depleted in refractory dust and carried positive Tm anomalies or (ii) CI chondrites are enriched in refractory dust and are not representative of solar composition for refractory elements. A new reference composition relevant to inner solar system bodies (CI?) is calculated by subtracting 0.15% of group II refractory inclusions to CI. The observed Tm anomalies in ordinary and enstatite chondrites and terrestrial rocks, relative to carbonaceous chondrites, indicate that material akin to carbonaceous chondrites must have represented a small fraction of the constituents of the Earth. Tm anomalies may be correlated with Ca isotopic fractionation in bulk planetary materials as they are both controlled by addition or removal of refractory material akin to fine-grained group II refractory inclusions.

  9. Rare earth element distributions and fractionation in plankton from the northwestern Mediterranean Sea.

    PubMed

    Strady, Emilie; Kim, Intae; Radakovitch, Olivier; Kim, Guebuem

    2015-01-01

    Rare earth element (REE) concentrations were measured for the first time in plankton from the northwestern Mediterranean Sea. The REE concentrations in phytoplankton (60-200 ?m) were 5-15 times higher than those in four size fractions of zooplankton: 200-500 ?m, 500-1000 ?m, 1000-2000 ?m and >2000 ?m. The concentrations within these zooplankton fractions exhibited the same ranges with some variation attributed to differences in zooplankton taxonomy. The REE concentrations in plankton were poorly related to the reported REE concentrations of seawater, but they correlated well with the calculated REE(3+), concentrations especially with regard to middle REE (MREEs) and heavy REEs (HREEs). Plankton and seawater revealed different PAAS-normalised REE distributions, with the greatest differences observed in the light REEs. Interestingly, a comparison of PAAS-normalized sediment particles from the study of Fowler et al. (1992) showed concentrations of the same order of magnitude and a similar REE distribution without MREE enrichment. Based on this comparison, we propose a conceptual model that emphasizes the importance of biological scavenging of REEs (especially LREEs) in surface waters. PMID:24972173

  10. Ocean particle chemistry: The fractionation of rare earth elements between suspended particles and seawater

    SciTech Connect

    Sholkovitz, E.R. ); Landing, W.M.; Lewis, B.L. )

    1994-03-01

    Sargasso Sea suspended particles were sequentially digested with three chemical treatments (acetic acid, mild HCl/HNO[sub 3], and HF/HNO[sub 3]/HCl in a bomb). The latter two treatments dissolve detrital minerals, while the acetic acid removes surface coatings (organic matter and Mn oxides). The rare earth element (REE) composition of the surface coatings, in marked contrast to the crust-like REE composition of the two detrital phases, is extensively fractionated with respect to both filtered seawater and the crust. Surface coatings are responsible for the removal and fractionation of REEs from seawater and, as such, play a key role in the marine geochemical cycles of trace elements. Relative to seawater, the surface coatings are systematically enriched tenfold across the trivalent REEs from Lu to La and develop large positive Ce-anomalies. The Ce-anomalies of the coatings switch from being negative (seawater-like) in the upper 100 m to being strongly positive at greater depths. The ingrowth of Ce and LREEs on particle surfaces reflects the in situ oxidation of dissolved Ce(III) to particulate Ce(IV), and the preferential removal of LREE(III)s over HREE(III)s. REEs(III) fractionation of this type is consistent with particle/solution models. Both processes appear to be related to the in situ formation of Mn oxide particles from the oxidation of dissolved Mn(II) in the upper 200 m of the water column. Preferential removal of LREEs in the upper waters is countered by their preferential release at depth due to remineralization of surface coatings on particles. A new method is explored for estimating the residence time of suspended particles by combining Ce concentration data of dissolved and surface-bound phases with the Ce(III) oxidation rate measurements of MOFFETT (1990). A Ce-based residence time of thirteen days is similar in magnitude to the value calculated from U-[sup 234]Th disequilibria in the Sargasso Sea.

  11. Effect of earthworms (Eisenia fetida) on the fractionation and bioavailability of rare earth elements in nine Chinese soils.

    PubMed

    Wen, Bei; Liu, Ying; Hu, Xiao-yu; Shan, Xiao-quan

    2006-05-01

    The effect of earthworm (Eisenia fetida) activity on soil pH, dissolved organic carbon (DOC), fraction distribution pattern and bioavailability of rare earth elements (REEs) Y, La, Ce, Pr and Nd in nine Chinese soils were investigated using pot experiments. A three-step extraction procedure recommended by the European Community (Standards, Measurements and Testing Programme) was used to fractionate REEs in soils into water soluble, exchangeable and carbonate bound (B1), Fe- and Mn-oxides bound (B2) and organic matter and sulfide bound (B3). Inoculated with earthworms, the soil pH, DOC and water-soluble rare earth elements fraction increased. A significant correlation was obtained between the increased DOC and the increased water-soluble REEs. REEs in fraction B1 increased after earthworm inoculation, while those in fraction B3 decreased. No significant differences were observed for REEs in fraction B2. The biomass and the concentrations of REEs in wheat shoots and roots increased after the treatment with earthworms. The results demonstrated that earthworm activity increased the mobility and bioavailability of REEs in soils. PMID:16289225

  12. Fractionation of Rare Earth Elements during Soil Formation along Feather River Basin Hillslopes in the California Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Steinert, T.; Weinman, B.; Yoo, K.; Mudd, S. M.; Kouba, C. M.; Maher, K.

    2013-12-01

    The mobility of rare earth elements (REE) has been debated by scientists for years. This study presents soil and soil moisture data from an ongoing study that examines how REEs fractionate as rock weathers into soil. The Middle Fork Feather River in Northern California, the location of the study site, takes advantage of an erosional signal propagating through the basin and compares traditional methods of REE normalization then contrasts them with elemental losses based on mass balance calculations (tau). Analyzed by ICP-MS using the whole-rock Li-borate dissolution method, soil and water sample collection took place along two differentially eroding hill slopes (a shallow slope above the knick-point and a more inclined slope below the knick-point). Using Zr as an immobile element, the mass-balance method clearly portrays REE fractionation occurring within the soils, whereas traditional REE normalization patterns do not clearly display fractionation relative to the parent material. While REEs fractionate approximately to the same extent in the topmost soils of both hill slopes, the more actively eroding hill slope fractionates REEs faster because of a faster rate of soil chemical weathering. While the full meaning of this work is still underway, current progress indicates that significant REE fractionation occurs during chemical weathering, implying that using REEs as tracers for surfaces processes requires significant care.

  13. Siderophile Element Fractionation in the Earth's Core: Direct Estimate of Partition Coefficients from Primitive Siberian Flood Basalts

    NASA Astrophysics Data System (ADS)

    Morgan, J. W.; Walker, R. J.

    2001-12-01

    Evidence from Os isotopes suggests that the siderophile element signature in some deep-mantle plumes may be derived from the outer core. The siderophile element pattern in the least fractionated plume basalts therefore may reflect solid-liquid metal fractionation, rather than that from partial melting of the upper mantle. Partition coefficients (D) derived from IIAB irons are governed by three major factors; element melting point, atomic radius and electron configuration. Values for Au, Ni, Re and the heavy platinum group elements (HPGE) plotted against melting point lie on a hyperbola with Os at the maximum. The light PGE (LPGE) also show a trend of increasing D with melting point but lie below the HPGE trend, perhaps due to differences in free atom electronic configuration. Siberian Flood Basalts (SFB) are of plume origin, and the Mokulaevsky and Morongovsky flows are the least crustally contaminated. Abundances of Ni, Rh, Pd, Ir, Pt and Au in these flows plot on a smooth curve against melting point when chondrite-normalized, but not when mantle-normalized. Thus, we explore the possibility that the SFB distributions reflect fractionation in the core rather than in the upper mantle. For 5.5 per cent crystallization, iron meteorite data yield much less fractionation of Ir than is seen in SFB, suggesting that D for Ir in the Earth's core is larger. Inversion of the SFB data yields a smooth curve when D values of PGE, Au and Ni are plotted against melting point. The D value for Ir is estimated to be about 5 times larger than in iron meteorites. If values for Re and Os are similarly enhanced, as suggested by high pressure experiments, Os isotopes in plumes may be more compatible with gradual formation of the inner core rather than early growth to the present size.

  14. Rare earth elements in intertidal sediments of Bohai Bay, China: concentration, fractionation and the influence of sediment texture.

    PubMed

    Zhang, Yong; Gao, Xuelu; Arthur Chen, Chen-Tung

    2014-07-01

    Surface sediments from intertidal Bohai Bay were assessed using a four-step sequential extraction procedure to determine their concentrations of rare earth elements (REEs) and the chemical forms in which those elements were present. The normalized ratios La/Gd and La/Yb showed that LREE contents were not significantly higher than the middle REEs or HREE contents. A negative Ce anomaly and positive Eu were observed in sand and silty sand sediments, whereas no significant Ce or Eu anomaly was found in clayey silt sediments. Residual fraction of REEs accounted for the majority of their total concentrations. Middle REEs were more easily leached than other REEs, especially in clayey silt sediment. REEs contents in the surface sediment from the intertidal Bohai Sea were consistent with data from the upper continental crust and China shallow sea sediments, indicating that they were generally unaffected by heavily anthropogenic effects from adjacent areas. PMID:24793516

  15. Thulium anomalies and rare earth element patterns in meteorites and Earth: Nebular fractionation and the nugget effect

    E-print Network

    Dauphas, N

    2015-01-01

    This study reports the bulk rare earth element (REEs, La-Lu) compositions of 41 chondrites, including 32 falls and 9 finds from carbonaceous (CI, CM, CO and CV), enstatite (EH and EL) and ordinary (H, L and LL) groups, as well as 2 enstatite achondrites (aubrite). The CI-chondrite-normalized REE patterns and Eu anomalies in ordinary and enstatite chondrites show more scatter in more metamorphosed than in unequilibrated chondrites. This is due to parent-body redistribution of the REEs in various carrier phases during metamorphism. The dispersion in REE patterns of equilibrated ordinary chondrites is explained by the nugget effect associated with concentration of REEs in minor phosphate grains. Terrestrial rocks and samples from ordinary and enstatite chondrites display negative Tm anomalies of ~-4.5 % relative to ca chondrites. In contrast, CM, CO and CV (except Allende) show no significant Tm anomalies. Allende CV chondrite shows large excess Tm (~+10 %). These anomalies are similar to those found in group II...

  16. Fractionation of rare-earth elements in allanite and monazite as related to geology of the Mt. Wheeler mine area, Nevada

    USGS Publications Warehouse

    Lee, D.E.; Bastron, H.

    1967-01-01

    Rare-earth contents of 20 allanites and 13 monazites, accessory minerals from a restricted outcrop area of intrusive granitic rocks, are reported. A quantity called sigma (??), which is the sum of the atomic percentages of La, Ce and Pr, is used as an index of composition with respect to the rare-earth elements. Values of sigma vary from 61.3 to 80.9 at.% for these allanites and monazites, representing an appreciable range of composition in terms of the rare-earth elements. Degree of fractionation of rare earths varies directly with CaO content of the granitic rocks, which in turn depends largely on proximity of limestone. Four xenoliths included in the study suggest that spotty mosaic equilibria are superimposed on the regional gradients and that locally the degree of fractionation of rare earths responds to whole rock composition over distances of a few yards or less. The chemistry of the granitic rocks under study appears to be similar in some respects to that of alkalio rocks and carbonatites. Allanites from the most calcium-rich rocks show a pronounced concentration of the most basic rare earths, and whole-rock concentrations of such rare constituents as total cerium earths, Zr, F, Ti, Ba and Sr increase sympathetically with whole-rock calcium. The explanation for the concentration gradients observed in this chemical system must involve assimilation more than magmatic differentiation. ?? 1967.

  17. Impact of plant species, substrate types and porosity on the fractionation of rare-earth elements in plants

    NASA Astrophysics Data System (ADS)

    Semhi, K.; Clauer, N.; Chaudhuri, S.

    2009-04-01

    The distribution and content of rare-earth elements (REEs) were determined in two radish species (Raphanus sativus and Raphanus raphanistrum) that were grown under laboratory-controlled conditions, in three substrates consisting in illite for one and in smectite for the two others, the two latter being of the same type but with different porosities. The plants were split into two segments: the leaves and the stems+roots. The results indicate that both species pick up systematically higher amounts of REEs when grown in the illite substrate, considering that the smectite contains about 3 times more REEs. In R. sativus, the REE concentration of the leaves and of the stems+roots, whatever the substrate, ranges from 1.4 to 1.9 ?g/g. After normalization to the substrate in which they grew, the distribution patterns for the leaves of those from illite substrate are nearly flat, but irregular with a positive Eu anomaly. Those for the stems+roots are similar, but enriched in heavy REEs, also with a positive Eu anomaly. The REE concentrations of the leaves and the stems+roots of R. sativus grown in smectite are analytically similar at 1.6 and 1.4 ?g/g, respectively. The REE distribution patterns for the two organs, normalized again to those of the substrate, are very similar, flat with a distinct Eu anomaly. The heavy REE of the stems+roots of R. sativus grown on illite are enriched relative to those of the leaves, and a distinct positive Eu anomaly is observed in both the leaves and stems+roots from species grown on both illite and smectite. In the case of R. raphanistrum, the REE concentrations of the leaves and the stems+roots for those grown in the illite substrate were found to be significantly different at 11.0 and 6.6 ?g/g, respectively. The REE distribution patterns for the two different plant organs normalized to those of the substrates were found to be quite similar, all being quite flat, with a more or less pronounced Ce negative anomaly, and a prominent positive Gd anomaly. When grown on smectite, the REE concentrations of the leaves and the stems+roots were about 7.2 and 6.3 ?g/g, respectively. The REE distribution patterns for the leaves and the stems+roots normalized to the corresponding smectite substrate are very closely similar, each having a nearly flat pattern with a slight but not significant negative Ce anomaly and a similar positive Gd anomaly. When grown on the smectite substrate with a different porosity, the leaves and the stems+roots had significantly higher REE concentrations of 9.3 and 19.7 ?g/g, respectively. Relative to the substrate REE pattern, the two organs had nearly identical flat REE distribution patterns, with a slight negative Ce anomaly and positive Gd and Er anomalies, In summary, the REE take up is more plant species dependent than mineral composition dependent: R. raphanistrum takes up 3.5 to 6.7 times more REEs than R. sativus, depending on the substrate, its porosity and the considered plant segments. Increased substrate porosity favors the pick up of the REEs, but no particular uptake is observed in leaves relative to that in the combined stems and roots. The transfer of the REEs from minerals to plant organs does not appear to induce systematically identical patterns. The effect of the plant species in the elemental uptake suggests that the root exudates are different, with a varied control on the micro-organism activity in the rhizosphere and probably different microbial compounds. New questionings about the identification of the organic compounds that influence and control the process of elemental exchanges activated by the root exudates in the soils within the rhizosphere, are also raised.

  18. Controls on the distribution and fractionation of yttrium and rare earth elements in core sediments from the Mandovi estuary, western India

    NASA Astrophysics Data System (ADS)

    Prajith, A.; Rao, V. Purnachandra; Kessarkar, Pratima M.

    2015-01-01

    Mineralogy, major elements (Fe, Mn and Al), rare earths and yttrium (REY) of bulk sediments were analyzed in four gravity cores recovered along the main channel of the Mandovi estuary, western India, to determine the sources and controls on REY distribution. The accelerator mass spectrometer (AMS) ages of total organic carbon indicated modern age for the sediments of the upper estuary and, maximum mean ages of 1588 years AD and 539 years AD for the bottom sediments of the cores in the lower estuary and bay, respectively. The sediments of the upper/middle estuary showed abundant hematite, magnetite and goethite and high Fe, Mn, total-REE (?REE) and Y, while those in the lower estuary/bay showed abundant silicate minerals and relatively low Fe, Mn, ?REE and Y. ?REE showed significant correlation with clay and silt fractions and Y, Al and organic carbon (OC) content of the sediments. The light to heavy REE ratios (LREE/HREE) of sediments were lower than in Post-Archean Australian Shale (PAAS). The PAAS-normalized rare earths and yttrium (REY; Y inserted between Dy and Ho) patterns of sediments showed middle REE (MREE)- and HREE-enrichment with positive Eu anomaly (Eu/Eu*) and variable Ce anomaly (Ce/Ce*). The REY of sediments is primarily controlled by its texture and REE of source sediment, which is ore material-dominated in the upper/middle estuary and silicate material-dominated in the lower estuary/bay. Low LREE/HREE ratios suggest that very fine-grained sediments were carried away from the estuary because of high-energy conditions. Fractionations of REY (Y/Ho, Sm/Nd, Ce/Ce* and Eu/Eu*) are controlled by different mechanisms. High Y/Ho ratios in clayey silts are due to redistribution of Y and Ho by adsorption onto organic-rich, clays. Variations in Sm/Nd ratios are similar to that of Eu/Eu* in cores from the lower estuary/bay and are controlled by mineral constituents of the sediments. Positive Ce and Eu anomalies are inherited from ore material, and ore material and source rocks, respectively. Negative Ce anomaly is related to source rock material and influenced by lanthanum enrichment at certain sediment intervals.

  19. Are C1 chondrites chemically fractionated - A trace element study

    NASA Astrophysics Data System (ADS)

    Ebihara, M.; Wolf, R.; Anders, E.

    1982-10-01

    Six C1 chondrite samples and a C2 xenolith from the Plainview H5 chondrite were analyzed by radiochemical neutron activation for a large variety of elements, including rare earths. The sample processing is described, including the irradiation, chemical procedure, rare earths separation, counting techniques, radiochemical purity check, and chemical yields. The results of consistency checks on a number of elements are discussed. Abundances for siderophiles, volatiles, and rare earths are presented and discussed. Tests are presented for fractionation of rare earths and other refractories, compositional uniformity of C1's, and interelement correlations. There is no conclusive evidence for nebular fractionation affecting C1's. Three fractionation-prone rare earths have essentially the same relative abundances in C1's and all other chondrite classes, and hence are apparently not fractionated in C1's.

  20. Condensation and fractionation of rare earths in the solar nebula

    NASA Technical Reports Server (NTRS)

    Davis, A. M.; Grossman, L.

    1979-01-01

    The condensation behavior of the rare earth elements in the solar nebula is calculated on the basis of the most recent thermodynamic data in order to construct a model explaining group II rare earth element patterns in Allende inclusions. Models considered all involve the removal of large fractions of the more refractory heavy rare earth elements in an early condensate, followed by the condensation of the remainder at a lower temperature. It is shown that the model of Boynton (1975) in which one rare earth element component is dissolved nonideally in perovskite according to relative activity coefficients can not reasonably be made to fit the observed group II patterns. A model in which two rare earth components control the patterns and dissolve ideally in perovskite is proposed and shown to be able to account for the 20 patterns by variations of the perovskite removal temperature and the relative proportions of the two components.

  1. Alkali metal and rare earth element evolution of rock-forming minerals from the Gatumba area pegmatites (Rwanda): Quantitative assessment of crystal-melt fractionation in the regional zonation of pegmatite groups

    NASA Astrophysics Data System (ADS)

    Hulsbosch, Niels; Hertogen, Jan; Dewaele, Stijn; André, Luc; Muchez, Philippe

    2014-05-01

    This study presents a general model for the evaluation of Rayleigh fractional crystallisation as the principal differentiation mechanism in the formation of regionally zoned common and rare-element pegmatites. The magmatic evolution of these systems from a granitic source is reconstructed by means of alkali element and rare earth element (REE) analyses of rock-forming minerals (feldspars, micas and tourmaline), which represent a whole sequence of regional pegmatite zonation. The Gatumba pegmatite field (Rwanda, Central Africa) is chosen as case study area because of its well-developed regional zonation sequence. The pegmatites are spatially and temporally related to peraluminous G4-granites (986 ± 10 Ma). The regional zonation is developed around a G4-granite and the proximal pegmatites grade outwardly into biotite, two-mica and muscovite pegmatites. Rare-element (Nb-Ta-Sn) pegmatites occur most distal from the granite.

  2. Alkali element constraints on Earth-Moon relations

    NASA Technical Reports Server (NTRS)

    Norman, M. D.; Drake, M. J.; Jones, J. H.

    1994-01-01

    Given their range of volatilities, alkali elements are potential tracers of temperature-dependent processes during planetary accretion and formation of the Earth-Moon system. Under the giant impact hypothesis, no direct connection between the composition of the Moon and the Earth is required, and proto-lunar material does not necessarily experience high temperatures. Models calling for multiple collisions with smaller planetesimals derive proto-lunar materials mainly from the Earth's mantle and explicitly invoke vaporization, shock melting and volatility-related fractionation. Na/K, K/Rb, and Rb/Cs should all increase in response to thermal volatization, so theories which derive the Moon substantially from Earth's mantle predict these ratios will be higher in the Moon than in the primitive mantle of the Earth. Despite the overall depletion of volatile elements in the Moon, its Na/K and K/Rb are equal to or less than those of Earth. A new model presented here for the composition of Earth's continental crust, a major repository of the alkali elements, suggests the Rb/Cs of the Moon is also less than that of Earth. Fractionation of the alkali elements between Earth and Moon are in the opposite sense to predictions based on the relative volatilities of these elements, if the Moon formed by high-T processing of Earth's mantle. Earth, rather than the Moon, appears to carry a signature of volatility-related fractionation in the alkali elements. This may reflect an early episode of intense heating on Earth with the Moon's alkali budget accreting from cooler material.

  3. Rare earth elements: end use and recyclability

    USGS Publications Warehouse

    Goonan, Thomas G.

    2011-01-01

    Rare earth elements are used in mature markets (such as catalysts, glassmaking, lighting, and metallurgy), which account for 59 percent of the total worldwide consumption of rare earth elements, and in newer, high-growth markets (such as battery alloys, ceramics, and permanent magnets), which account for 41 percent of the total worldwide consumption of rare earth elements. In mature market segments, lanthanum and cerium constitute about 80 percent of rare earth elements used, and in new market segments, dysprosium, neodymium, and praseodymium account for about 85 percent of rare earth elements used. Regardless of the end use, rare earth elements are not recycled in large quantities, but could be if recycling became mandated or very high prices of rare earth elements made recycling feasible.

  4. Isotopic fractionation of alkali earth metals during carbonate precipitation

    NASA Astrophysics Data System (ADS)

    Yotsuya, T.; Ohno, T.; Muramatsu, Y.; Shimoda, G.; Goto, K. T.

    2014-12-01

    The alkaline earth metals such as magnesium, calcium and strontium play an important role in a variety of geochemical and biological processes. The element ratios (Mg/Ca and Sr/Ca) in marine carbonates have been used as proxies for reconstruction of the past environment. Recently several studies suggested that the study for the isotopic fractionation of the alkaline earth metals in marine carbonates has a potentially significant influence in geochemical research fields (e.g. Eisenhauer et al., 2009). The aim of this study is to explore the influence of carbonate polymorphs (Calcite and Aragonite) and environmental factors (e.g., temperature, precipitation rate) on the level of isotopic fractionation of the alkaline earth metals. We also examined possible correlations between the level of isotopic fractionation of Ca and that of other alkaline earth metals during carbonate precipitation. In order to determine the isotope fractionation factor of Mg, Ca and Sr during carbonate precipitation, calcite and aragonite were synthesized from calcium bicarbonate solution in which the amount of magnesium was controlled based on Kitano method. Calcium carbonates were also prepared from the mixture of calcium chlorite and sodium hydrogen carbonate solutions. The isotope fractionation factors were measured by MC-ICPMS. Results suggested that the level of isotopic fractionation of Mg during carbonate precipitation was correlated with that of Sr and that the change of the carbonate crystal structure could make differences of isotopic fractionations of Mg and Ca, however no difference was found in the case of Sr. In this presentation, the possible mechanism will be discussed.

  5. Trace and rare earth elements fractionation in volcanic- and sediment-hosted Mn ores: a study case of Sardinia (western Italy).

    NASA Astrophysics Data System (ADS)

    Sinisi, Rosa

    2015-04-01

    It is widely accepted that, regardless of the geological environment (continental, marine or hydrothermal), the occurrences of clay minerals and/or mineral phases with clay-type crystal structure (as zeolites and Mn-oxides), play a key role in the trace elements and REEs uptake processes. The REE resources are produced mostly from ion-adsorption type REE deposits of southern China that are formed by weathering of granitic rocks and subsequent chemical adsorption of REE on clay minerals. A significant group of minerals with a high metal uptake capacity is represented by Mn oxides. Their "tunnel" structure, in fact, allows both the absorption (inside the minerals) and adsorption (outside the minerals) of cations and anions producing metal accumulations with economic and environmental significance. However, the ores, mainly that forming within sedimentary environment, often have impurities due to presence of minerals unrelated to mineralization. These minerals can significantly alter the compositional features of the ores and suggest misleading conclusions. In Sardinia (Italy, western Mediterranean), Mn-oxide mineralizations occur and recently their origin has been discussed and identified (Sinisi et al. 2012). In this study the mineralogical and chemical compositions of the Sardinian sediment-hosted and volcanic-hosted Mn-ore are exhibit exploring the possibility that they can represent exploitable trace and REE mineralizations. High contents of metals characterize these Mn deposits. Besides some trace elements (Ni, Cr, Zn, Cu, As, Pb, and U) that commonly typify the Mn oxi-hydroxide ores, all rare earth elements showed high concentrations in the Sardinian deposits, comparable to those of the main actually exploited REE sinks. For this reason, a simple statistical data treatment (R-mode Factor Analysis) was performed on fifteen and nineteen samples of sediment-hosted and volcanic-hosted Mn ore respectively, in order to identify both the mineral phases trapping trace and REE in Mn ores from different geological settings and the geochemical processes promoting the metal accumulation. Results clearly showed that in the studied deposits only the contents of trace metals may be referred to uptake process on Mn mineral phases. On the contrary, REE are probably hosted in silicates, such as zircons and clay minerals, that also characterize the mineralization or their presence is due to redox processes not linked to Mn ore deposition. Sinisi R., Mameli P., Mongelli G., Oggiano G. (2012). Different Mn-ores in a continental arc setting: geochemical and mineralogical evidence from Tertiary deposits of Sardinia (Italy). Ore Geology Reviews, 47, 110-125.

  6. Mineral resource of the month: rare earth elements

    USGS Publications Warehouse

    U.S. Geological Survey

    2011-01-01

    The article provides information on rare earth elements, which are group of 17 natural metallic elements. The rare earth elements are scandium, yttrium and lanthanides and classified into light rare earth elements (LREE) and heavy rate earth elements (HREE). The principal ores of the rare earth elements are identified. An overview of China's production of 97 percent of the rare earths in the world is provided. Commercial applications of rare earths are described.

  7. Rare Earth Element Mines, Deposits, and Occurrences

    USGS Publications Warehouse

    Orris, Greta J.; Grauch, Richard I.

    2002-01-01

    Data on rare earth (including yttrium) mines, deposits, and occurrences were compiled as part of an effort by the USGS and the University of Arizona Center for Mineral Resources to summarize current knowledge on the supply and demand outlook and related topics for this group of elements. Economic competition and environmental concerns are increasingly constraining the mining and processing of rare earths from the Mountain Pass mine in California. For many years, the deposit at Mountain Pass was the world's dominant source of rare earth elements and the United States was essentially self-sufficient. Starting approximately 10 years ago, the U.S. has become increasingly dependent (> 90 percent of separated rare earths) upon imports from China, now the dominant source of rare earths. A knowledge of the known economic and noneconomic sources of rare earths is basic to evaluating the outlook for rare earth supply and associated issues.

  8. Systematic variation of rare-earth elements in cerium-earth minerals

    USGS Publications Warehouse

    Murata, K.J.; Rose, H.J., Jr.; Carron, M.K.; Glass, J.J.

    1957-01-01

    In a continuation of a study reported previously, rare-earth elements and thorium have been determined in monazite, allanite, cerite, bastnaesite, and a number of miscellaneous cerium-earth minerals. A quantity called sigma (???), which is the sum of the atomic percentages of La, Ce, and Pr, is proposed as an index of composition of all cerium-earth minerals with respect to the rare-earth elements. The value of ??? for all of the minerals analysed falls between 58 and 92 atomic per cent. Monazites, allanites, and cerites cover the entire observed range, whereas bastnaesites are sharply restricted to the range between 80 and 92 atomic per cent. The minimum value of ??? for a cerium-earth mineral corresponds to the smallest possible unit-cell size of the mineral. In monazite, this structurally controlled minimum value of ??? is estimated to be around 30 atomic per cent. Neodymium, because of its abundance, and yttrium, because of its small size, have dominant roles in contraction of the structure. In the other direction, the limit of variation in composition will be reached when lanthanum becomes the sole rare-earth element in a cerium-earth mineral. Cerium-earth minerals from alkalic rocks are all characterized by values of ??? greater than 80 atomic per cent, indicating that the processes that formed these rocks were unusually efficient in fractionating the rare-earth elements-efficient in the sense that a highly selected assemblage is produced without eliminating the bulk of these elements. Analyses of inner and outer parts of two large crystals of monazite from different deposits show no difference in ??? in one crystal and a slightly smaller value of ??? in the outer part of the other crystal compared to the inner part. The ??? of monazites from pegmatites that intrude genetically related granitic rocks in North Carolina is found to be either higher or lower than the ??? of monazites in the intruded host rock. These results indicate that the fractionation of the rare-earth elements is not a simple unidirectional process. When a cerium-earth mineral undergoes replacement, its rare-earth elements may be fractionated into two parts, one forming a new mineral with ??? that is smaller, and the other a second new mineral with ??? that is larger than that of the original mineral. The complete analysis of a cerium-earth mineral to determine its ??? is time consuming. The discovery of a direct relationship between ??? and the Ce/(Nd + Y) atomic ratio in cerium earth minerals allows a rapid determination of ??? from spectrograms obtained in a previously described method for determining thorium in these minerals. ?? 1957.

  9. Moving KML geometry elements within Google Earth

    NASA Astrophysics Data System (ADS)

    Zhu, Liang-feng; Wang, Xi-feng; Pan, Xin

    2014-11-01

    During the process of modeling and visualizing geospatial information on the Google Earth virtual globe, there is an increasing demand to carry out such operations as moving geospatial objects defined by KML geometry elements horizontally or vertically. Due to the absence of the functionality and user interface for performing the moving transformation, it is either hard or impossible to interactively move multiple geospatial objects only using the existing Google Earth desktop application, especially when the data sets are in large volume. In this paper, we present a general framework and associated implementation methods for moving multiple KML geometry elements within Google Earth. In our proposed framework, we first load KML objects into the Google Earth plug-in, and then extract KML geometry elements from the imported KML objects. Subsequently, we interactively control the movement distance along a specified orientation by employing a custom user interface, calculate the transformed geographic location for each KML geometry element, and adjust geographic coordinates of the points in each KML objects. And finally, transformed KML geometry elements can be displayed in Google Earth for 3D visualization and spatial analysis. A key advantage of the proposed framework is that it provides a simple, uniform and efficient user interface for moving multiple KML geometry elements within Google Earth. More importantly, the proposed framework and associated implementations can be conveniently integrated into other customizable Google Earth applications to support interactively visualizing and analyzing geospatial objects defined by KML geometry elements.

  10. TWO EXTRASOLAR ASTEROIDS WITH LOW VOLATILE-ELEMENT MASS FRACTIONS

    SciTech Connect

    Jura, M.; Xu, S.; Klein, B.; Zuckerman, B.; Koester, D. E-mail: sxu@astro.ucla.edu E-mail: ben@astro.ucla.edu

    2012-05-01

    Using ultraviolet spectra obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope, we extend our previous ground-based optical determinations of the composition of the extrasolar asteroids accreted onto two white dwarfs, GD 40 and G241-6. Combining optical and ultraviolet spectra of these stars with He-dominated atmospheres, 13 and 12 polluting elements are confidently detected in GD 40 and G241-6, respectively. For the material accreted onto GD 40, the volatile elements C and S are deficient by more than a factor of 10 and N by at least a factor of 5 compared to their mass fractions in primitive CI chondrites and approach what is inferred for bulk Earth. A similar pattern is found for G241-6 except that S is undepleted. We have also newly detected or placed meaningful upper limits for the amount of Cl, Al, P, Ni, and Cu in the accreted matter. Extending results from optical studies, the mass fractions of refractory elements in the accreted parent bodies are similar to what is measured for bulk Earth and chondrites. Thermal processing, perhaps interior to a snow line, appears to be of central importance in determining the elemental compositions of these particular extrasolar asteroids.

  11. Stable Isotope Fractionation of Metallic Elements

    NASA Astrophysics Data System (ADS)

    Albarede, F.

    2001-12-01

    The 70s and the 80s saw the demonstration that some anomalous isotope compositions in planetary material are inherited from heterogeneities in the Solar Nebula and that some others reflect spallation induced by strong radiation events. In addition, a variety of mass-independent fractionation processes were shown to affect the isotopic composition of atmospheric O, C, and S. In the mean time, the patterns of mass-dependent fractionation of most elements, notably metals, remained largely ignored, presumably because the state-of-the-art precision of existing analytical techniques (mostly double-spike) was inadequate. The debate largely focused on why no isotopic fractionation could actually be observed, e.g., for K and Fe in planetary objects, within the limits of the current analytical uncertainties (0.1 to 1~‰ ). The advent of multiple-collector ICP MS suddenly improved the precision on isotopic measurements to a typical 40 ppm on elements such as Cu, Zn, Fe, Mg, Mo, etc. The ongoing exploration of the stable isotope geochemistry of metallic elements is revealing that their natural isotopic variability is much more widespread and stronger than previously anticipated, typically 1~‰ for Zn and Fe to 10~‰ for Cu. The mechanisms of isotopic fractionation that create this variability remain to be determined. The bulk of Zn and Fe in planetary material is apparently derived from an isotopically homogeneous source. The first data on meteorites reveal, however, that the isotopic heterogeneities of Cu and Zn in planetary objects correlate with 16O excess. Redox reactions cannot be the deus-ex-machina of the isotope geochemistry of metals: isotope fractionation in ores and soils is far more ubiquitous and far stronger for Cu than for Fe. Cu fractionation by ion exchange in solution is much stronger for chloride complexes than for free ions in nitric solutions. Volatilization processes also need to be better understood: the Zn isotope variability of iron meteorites is nearly an order of magnitude larger than that of the rest of planetary material altogether regardless of its apparent volatile element depletion. A careful investigation of the coordination and of molecular symmetry in vapor, aqueous solutions, solids and liquid metals is a pre-requisite to the understanding of these newly discovered isotopic effects.

  12. Light element controlled iron isotope fractionation in planetary cores

    NASA Astrophysics Data System (ADS)

    Shahar, A.; Hillgren, V. J.; Horan, M. F.; Duke, L.; Mock, T. D.

    2013-12-01

    Using iron isotope fractionations measured in planetary and meteorite samples to trace planetary differentiation or formation has yielded contradictory results. Iron from high-Ti lunar basalts is more enriched in 57Fe/54Fe than mantle-derived terrestrial samples, in contrast to the isotopic similarity for almost every other element between the Earth and Moon. SNC (Shergottite, Nakhlite, Chassigny) and HED (Howardite, Eucrite, Diogenite) meteorites, which are thought to be derived from the mantles of Mars and Vesta, respectively, show no isotopic fractionation relative to chondrites. While the Bulk Silicate Earth (BSE) value is debated, recent work has shown effectively that basalts (mid-ocean ridge basalts, terrestrial basalts, and ocean island basalts) are enriched in 57Fe/54Fe relative to chondrites, but the causes of that fractionation are unclear (Craddock et al. 2013). Angrites, basaltic achondrite meteorites, also show enrichment in ?57Fe (Wang et al. 2012). Possible mechanisms include high-pressure core formation, oxidation during perovskite disproportionation, evaporation during the giant impact, and mantle melting. It is important to reconcile why the Earth's basalts are enriched in 57Fe/54Fe but the meteorites from Mars and Vesta are not. One possible explanation is that Mars and Vesta are smaller and the lower pressure attenuated the potential Fe fractionation during core formation. A second possibility is that the intrinsic oxidation states of the planets are causing the differences. However, another option is that the light elements (e.g. S, C, O, H, Si) in the cores of differentiated bodies control the iron isotope fractionation during differentiation. We have conducted experiments at 1 GPa and 1650-1800°C in a piston cylinder apparatus to address how sulfur, carbon and silicon alloyed with iron affect the iron isotopic fractionation between metallic alloy and silicate melt. We find that sulfur has the greatest effect on the iron isotopic fractionation at these conditions.This has wide implications for tracing differentiation processes as the nature of the light element in the core is directly related to the mode of formation and the conditions present. Therefore, by comparing the experimental data with meteoritic data, the composition of planetary cores can be estimated.

  13. Isotope fractionation in surface ionization ion source of alkaline-earth iodides

    SciTech Connect

    Suzuki, T.; Kanzaki, C.; Nomura, M.; Fujii, Y.

    2012-02-15

    The relationship between the isotope fractionation of alkaline-earth elements in the surface ionization ion source and the evaporation filament current, i.e., filament temperature, was studied. It was confirmed that the isotope fractionation depends on the evaporation filament temperature; the isotope fractionation in the case of higher temperature of filament becomes larger. The ionization and evaporation process in the surface ionization ion source was discussed, and it was concluded that the isotope fractionation is suppressed by setting at the lower temperature of evaporation filament because the dissociations are inhibited on the evaporation filament.

  14. Rare Earth Element Interferences in Collision Cell and Standard

    E-print Network

    Rare Earth Element Interferences in Collision Cell and Standard Mode ICP-MS Analyses of Arsenic the idea that Rare Earth Elements are rare 2.Look at the extent of the Rare Earth Element interference this interference challenge Overview: #12;Rare Earth Technology Application(s) REE required Catalysts ·Oil

  15. Cosmochemical fractionation by collisional erosion during the Earth's accretion.

    PubMed

    Boujibar, Asmaa; Andrault, Denis; Bolfan-Casanova, Nathalie; Bouhifd, Mohamed Ali; Monteux, Julien

    2015-01-01

    Early in the Solar System's history, energetic collisions of differentiated bodies affected the final composition of the terrestrial planets through partial destruction. Enstatite chondrites (EC) are the best candidates to represent the primordial terrestrial precursors as they present the most similar isotopic compositions to Earth. Here we report that collisional erosion of >15% of the early Earth's mass can reconcile the remaining compositional differences between EC and the Earth. We base our demonstration on experimental melting of an EC composition at pressures between 1 bar and 25 GPa. At low pressures, the first silicate melts are highly enriched in incompatible elements Si, Al and Na, and depleted in Mg. Loss of proto-crusts through impacts raises the Earth's Mg/Si ratio to its present value. To match all major element compositions, our model implies preferential loss of volatile lithophile elements and re-condensation of refractory lithophile elements after the impacts. PMID:26395157

  16. Cosmochemical fractionation by collisional erosion during the Earth's accretion

    PubMed Central

    Boujibar, Asmaa; Andrault, Denis; Bolfan-Casanova, Nathalie; Bouhifd, Mohamed Ali; Monteux, Julien

    2015-01-01

    Early in the Solar System's history, energetic collisions of differentiated bodies affected the final composition of the terrestrial planets through partial destruction. Enstatite chondrites (EC) are the best candidates to represent the primordial terrestrial precursors as they present the most similar isotopic compositions to Earth. Here we report that collisional erosion of >15% of the early Earth's mass can reconcile the remaining compositional differences between EC and the Earth. We base our demonstration on experimental melting of an EC composition at pressures between 1 bar and 25 GPa. At low pressures, the first silicate melts are highly enriched in incompatible elements Si, Al and Na, and depleted in Mg. Loss of proto-crusts through impacts raises the Earth's Mg/Si ratio to its present value. To match all major element compositions, our model implies preferential loss of volatile lithophile elements and re-condensation of refractory lithophile elements after the impacts. PMID:26395157

  17. Cosmochemical fractionation by collisional erosion during the Earth's accretion

    NASA Astrophysics Data System (ADS)

    Boujibar, Asmaa; Andrault, Denis; Bolfan-Casanova, Nathalie; Bouhifd, Mohamed Ali; Monteux, Julien

    2015-09-01

    Early in the Solar System's history, energetic collisions of differentiated bodies affected the final composition of the terrestrial planets through partial destruction. Enstatite chondrites (EC) are the best candidates to represent the primordial terrestrial precursors as they present the most similar isotopic compositions to Earth. Here we report that collisional erosion of >15% of the early Earth's mass can reconcile the remaining compositional differences between EC and the Earth. We base our demonstration on experimental melting of an EC composition at pressures between 1 bar and 25 GPa. At low pressures, the first silicate melts are highly enriched in incompatible elements Si, Al and Na, and depleted in Mg. Loss of proto-crusts through impacts raises the Earth's Mg/Si ratio to its present value. To match all major element compositions, our model implies preferential loss of volatile lithophile elements and re-condensation of refractory lithophile elements after the impacts.

  18. Alkaline Element Fractionations in LL-chondritic Breccias

    NASA Astrophysics Data System (ADS)

    Misawa, K.; Yokoyama, T.; Okano, O.

    2010-12-01

    Introduction: Fractionation of moderately volatile lithophile elements including alkaline elements was an important process in the early solar system. Alkali-rich igneous fragments (K-rich fragments) were found in brecciated LL-chondrites. These fragments in Kraehenberg (LL5), Bhola (LL3-6), and Yamato (Y)-74442 (LL4) show fractionated alkaline element patterns; for example, abundances of alkaline elements in the Kraehenberg fragment are ~0.5 x CI for Na, ~12 x CI for K,~45 x CI for Rb, and ~70 x CI for Cs [1]. In order to understand moderately volatile element fractionations, we have undertaken mineralogical and petrological studies on K-rich fragments in Kraehenberg [1], Bhola [2], and Y-74442 [3, 4]. Results and Discussion: Kraehenberg, Bhola, and Y-74442 consist of mineral fragments, K-rich fragments, impact-melt clasts, chondrules, and matrix. K-rich fragments in these meteorites are composed of 10-100 µm-sized euhedral olivine (~60 vol.%) and groundmass of brown glasses (~40 vol.%, including microcrystalline pyroxene) which are highly enriched in alkaline elements. Dendritic pyroxene and chromite (~1 µm in size) along with troilite (~10 µm in size) are commonly observed in the groundmass. The textures are different from those of impact melt clasts in ordinary chondrites. Chemical compositions of olivine in the K-rich fragments fall within the compositional range of equilibrated LL-chondrites (Fa26-32 [5]). Groundmass glasses in the Kraehenberg, Bhola, and Y-74442 fragments are almost identical in composition when plotted on a Na+K+Al-oxides-Ca+Mg+Fe-oxides-SiO2 ternary diagram [1]. The fractionation trend is also observed in an angular igneous fragment in Siena (LL5) [6]. The lack of K isotopic fractionation effects in the K-rich clast in Kraehenberg [7] implies that the enrichment of (heavier) alkaline elements occurred near-equilibrium conditions. The K-rich fragments in Kraehenberg and Y-74442 could be early solar system materials (~4.56 Ga [8, 9]). Similarities in textures, compositions, and fractionation patterns of the K-rich fragments suggest that they might be formed from related precursor materials with related processes. Complementarity of K-rich fragments and differentiated body alkali abundance patterns suggests that the fractionation could have occurred in the early solar nebula. Refs: [1] Wlotzka F. et al. (1983) Geochim. Cosmochim. Acta 47, 743. [2] Noonan A.F. et al. (1978) Geol. Survey Open File Report 78-701, 311. [3] Yanai K. et al. (1978) Mem. Natl. Inst. Polar Res. Spec. Issue 8, 110. [4] Ikeda Y. and Takeda H. (1979) Mem. Natl. Inst. Polar Res. Spec. Issue 15, 123. [5] Dodd R.T. (1981) Meteorites pp. 368, Cambridge Univ. Press. [6] Fodor R.V. and Keil K. (1978) Catalog of lithic fragments in LL-chondrites, Inst. Meteoritics Spec. Publ. No. 19, pp. 38, Univ. New Mexico, Albuquerque. [7] Humayun M. and Clayton R.N. (1995) Geochim. Cosmochim. Acta 59, 2131. [8] Kempe W. and Mueller O. (1969) Meteorite Res., pp. 418. [9] Nishiya N. et al. (1995) Okayama Univ. Earth Sci. Rep. 2, 91.

  19. Rare earth element systematics in hydrothermal fluids

    SciTech Connect

    Michard, A. )

    1989-03-01

    Rare earth element concentrations have been measured in hydrothermal solutions from geothermal fields in Italy, Dominica, Valles Caldera, Salton Sea and the Mid-Atlantic Ridge. The measured abundances show that hydrothermal activity is not expected to affect the REE balance of either continental or oceanic rocks. The REE enrichment of the solutions increases when the pH decreases. High-temperature solutions (> 230{degree}C) percolating through different rock types may show similar REE patterns.

  20. Rare earth elements in synthetic zircon. 1. synthesis, and rare earth element and phosphorus doping.

    SciTech Connect

    Hanchar, J. M.; Finch, R. J.; Hoskin, W. O.; Watson, E. B.; Cherniak, D. J.; Mariano, A. N.; Chemical Engineering; George Washington Univ.; Univ. of Canterbury; Australian National Univ.; Rensselaer Polytechnic Inst.

    2001-05-01

    Sedimentary mineral assemblages commonly contain detrital zircon crystals as part of the heavy-mineral fraction. Age spectra determined by U-Pb isotopic analysis of single zircon crystals within a sample may directly image the age composition--but not the chemical composition--of the source region. Rare earth element (REE) abundances have been measured for zircons from a range of common crustal igneous rock types from different tectonic environments, as well as kimberlite, carbonatite, and high-grade metamorphic rocks, to assess the potential of using zircon REE characteristics to infer the rock types present in sediment source regions. Except for zircon with probable mantle affinities, zircon REE abundances and normalized patterns show little intersample and intrasample variation. To evaluate the actual variation in detrital zircon REE composition in a true sediment of known mixed provenance, zircons from a sandstone sample from the Statfjord Formation (North Sea) were analyzed. Despite a provenance including high-grade metasediment and granitoids and a range in zircon age of 2.82 b.y., the zircon REEs exhibit a narrow abundance range with no systematic differences in pattern shape. These evidences show zircon REE patterns and abundances are generally not useful as indicators of provenance.

  1. Note: Portable rare-earth element analyzer using pyroelectric crystal

    SciTech Connect

    Imashuku, Susumu Fuyuno, Naoto; Hanasaki, Kohei; Kawai, Jun

    2013-12-15

    We report a portable rare-earth element analyzer with a palm-top size chamber including the electron source of a pyroelectric crystal and the sample stage utilizing cathodoluminescence (CL) phenomenon. The portable rare-earth element analyzer utilizing CL phenomenon is the smallest reported so far. The portable rare-earth element analyzer detected the rare-earth elements Dy, Tb, Er, and Sm of ppm order in zircon, which were not detected by scanning electron microscopy-energy dispersive X-ray spectroscopy analysis. We also performed an elemental mapping of rare-earth elements by capturing a CL image using CCD camera.

  2. Rare earth element patterns in biotite, muscovite and tourmaline minerals

    SciTech Connect

    Laul, J.C.; Lepel, E.A.

    1986-04-21

    Rare earth element concentrations in the minerals biotite and muscovite from the mica schist country rocks of the Etta pegmatite and tourmalines from the Bob Ingersoll pegmatite have been measured by INAA and CNAA. The concentrations range from 10/sup -4/ g/g to 10/sup -10g//sub g/. The REE patterns of biotite, muscovite and tourmaline reported herein are highly fractionated from light to heavy REE. The REE concentrations in biotite and muscovite are high and indigenous. The pegmatite tourmalines contain low concentrations of REE. Variations in tourmaline REE patterns reflect the geochemical evolution of pegmatite melt/fluid system during crystallization.

  3. Anthropogenic Cycles of Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Du, X.; Graedel, T. E.

    2009-12-01

    This research will develop quantitatively resolved anthropogenic cycles and in-use stocks for the rare earth metals specifically cerium, lanthanum and dysprosium in Japan, China, and the U.S. for the year of 2007. Rare earth elements (REE) is a group of 17 scare metals widely used in a growing number of emerging technologies and have been in high demand for emerging technologies as raw materials during past the three decades. New market participants from newly industrializing countries, primarily China, have had strong impacts on the demand of share. Consequently, the importance to sustain a reliable, steady, uninterrupted supply on global market triggered comprehensive research to recognize and understand the life cycles of rare earths. Moreover, because China plays a dominant role in mining production since 1990, it requires the assessment for the countries, which are almost completely dependent on imports from China with respect to rare earth resources. The study aims to analyze the flows and stocks of rare earth elements individually as elemental form in spite of their natural geological co-occurrence and mixed composition in applications. By applying the method of Material Flow Analysis (MFA) work has been done on evaluating current and historical flows of specific technologically significant materials, for example, copper, zinc, nickel, etc., determining the stocks available in different types of reservoirs (e.g., lithosphere, in-use) and the flows among the reservoirs, developing scenarios of possible futures of metal use, and assessing the environmental and policy implications of the results. Therefore, REE as a new target deserves inclusion because of its potential demand-supply conflict and importance to secure the competitive advantage of technical innovation in future. This work will generate a quantitatively resolved anthropogenic life cycle and in-use stocks for REE for the main target countries for a chosen year, 2007, providing flows and stocks from mining to use to recycling quantifying the cycles for Japan, China and the U.S. as three representative types of consumers and paying attention to aspects of resource sustainability. Being well aware of the stages in the metal life cycle helps the sustainable development and policy making in long term. The goal is to consider REE resource availability, sustainability, and development strategies in the future that can sustain a reliable, steady, uninterrupted REE supply on the global market.

  4. Tipping elements in the Earth's climate system

    PubMed Central

    Lenton, Timothy M.; Held, Hermann; Kriegler, Elmar; Hall, Jim W.; Lucht, Wolfgang; Rahmstorf, Stefan; Schellnhuber, Hans Joachim

    2008-01-01

    The term “tipping point” commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term “tipping element” to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points. PMID:18258748

  5. Rare Earth Elements: A Tool for Understanding the Behaviour of Trivalent Actinides in the Geosphere

    SciTech Connect

    Buil, Belen; Gomez, Paloma; Garralon, Antonio; Turrero, M. Jesus

    2007-07-01

    Rare earth element (REE) concentrations have been determined in groundwaters, granite and fracture fillings in a restored uranium mine. The granitoids normalized REE patterns of groundwaters show heavy rare earth elements (HREE)-enrichment and positive Eu anomalies. This suggests that the REE are fractionated during leaching from the source rocks by groundwaters. Preferential leaching of HREE would be consistent with the greater stability of their aqueous complexes compared to those of the light rare earth elements (LREE), together with the dissolution of certain fracture filling minerals, dissolution/alteration of phyllosilicates and colloidal transport. (authors)

  6. Rare earth elements in weathering profiles and sediments of Minnesota: Implications for provenance studies

    USGS Publications Warehouse

    Morey, G.B.; Setterholm, D.R.

    1997-01-01

    The relative abundance of rare earth elements in sediments has been suggested as a tool for determining their source rocks. This correlation requires that weathering, erosion, and sedimentation do not alter the REE abundances, or do so in a predictable manner. We find that the rare earth elements are mobilized and fractionated by weathering, and that sediments derived from the weathered materials can display modifications of the original pattern of rare earth elements of some due to grain-size sorting of the weathered material. However, the REE distribution pattern of the provenance terrane can be recognized in the sediments.

  7. Xenon Fractionation, Hydrogen Escape, and the Oxidation of the Earth

    NASA Astrophysics Data System (ADS)

    Zahnle, K. J.; Catling, D. C.

    2014-12-01

    Xenon in Earth's atmosphere is severely mass fractionated and depleted compared to any plausible solar system source material, yet Kr is unfractionated. These observations seem to imply that Xe has escaped from Earth. Vigorous hydrodynamic hydrogen escape can produce mass fractionation in heavy gases. The required hydrogen flux is very high but within the range permitted by solar EUV heating when Earth was 100 Myrs old or younger. However this model cannot explain why Xe escapes but Kr does not. Recently, what appears to be ancient atmospheric xenon has been recovered from several very ancient (3-3.5 Ga) terrestrial hydrothermal barites and cherts (Pujol 2011, 2013). What is eye-catching about this ancient Xe is that it is less fractionated that Xe in modern air. In other words, it appears that a process was active on Earth some 3 to 3.5 billion years ago that caused xenon to fractionate. By this time the Sun was no longer the EUV source that it used to be. If xenon was being fractionated by escape — currently the only viable hypothesis — it had to be in Earth's Archean atmosphere and under rather modest levels of EUV forcing. It should be possible for Xe, but not Kr, to escape from Earth as an ion. In a hydrodynamically escaping hydrogen wind the hydrogen is partially ionized. The key concepts are that ions are much more strongly coupled to the escaping flow than are neutrals (so that a relatively modest flow of H and H+ to space could carry Xe+ along with it, the flux can be small enough to be consistent with diffusion-limited flux), and that Xe alone among the noble gases is more easily ionized than hydrogen. This sort of escape is possible along the polar field lines, although a weak or absent magnetic field would likely work as well. The extended history of hydrogen escape implicit in Xe escape in the Archean is consistent with other suggestions that hydrogen escape in the Archean was considerable. Hydrogen escape plausibly played the key role in creating oxidizing conditions at the surface of the Earth and setting the stage for the creation of an O2 atmosphere (Urey 1951, Catling et al 2001, Zahnle et al 2013). Catling, McKay, Zahnle (2001) Science 293, 839. Pujol, Marty, Burnard, Phillipot (2009) GCA 73, 6834. Pujol, Marty, Burgess (2011) EPSL 308, 298. Urey, H.C. (1952) PNAS 38, 351. Zahnle, Catling, Claire (2013) Ch. Geol. 362, 26.

  8. Levels of major and trace elements, including rare earth elements, and ²³?U in Croatian tap waters.

    PubMed

    Fiket, Željka; Rožmari?, Martina; Krmpoti?, Matea; Benedik, Ljudmila

    2015-05-01

    Concentrations of 46 elements, including major, trace, and rare earth elements, and (238)U in Croatian tap waters were investigated. Selected sampling locations include tap waters from various hydrogeological regions, i.e., different types of aquifers, providing insight into the range of concentrations of studied elements and (238)U activity concentrations in Croatian tap waters. Obtained concentrations were compared with the Croatian maximum contaminant levels for trace elements in water intended for human consumption, as well as WHO and EPA drinking water standards. Concentrations in all analyzed tap waters were found in accordance with Croatian regulations, except tap water from Šibenik in which manganese in concentration above maximum permissible concentration (MPC) was measured. Furthermore, in tap water from Osijek, levels of arsenic exceeded the WHO guidelines and EPA regulations. In general, investigated tap waters were found to vary considerably in concentrations of studied elements, including (238)U activity concentrations. Causes of variability were further explored using statistical methods. Composition of studied tap waters was found to be predominately influenced by hydrogeological characteristics of the aquifer, at regional and local level, the existing redox conditions, and the household plumbing system. Rare earth element data, including abundances and fractionation patterns, complemented the characterization and facilitated the interpretation of factors affecting the composition of the analyzed tap waters. PMID:25430011

  9. Rare earth element analysis indicates micropollutants in an urban estuary

    NASA Astrophysics Data System (ADS)

    Mohajerin, T. J.; Johannesson, K. H.; Kolker, A.; Burdige, D. J.; Chevis, D.

    2011-12-01

    Rare earth element analysis of Bayou Bienvenue waters shows anomalously high gadolinium, Gd, concentrations relative to its nearest neighbors in the REE series, europium and terbium. The anomalously high Gd concentrations indicate anthropogenic input from waste-water treatment plants in the area as anthropogenic Gd input can be traced back to its use as a contrast agent in magnetic resonance imaging in hospitals. Others have shown that anomalously high levels of Gd in natural waters are likely to be associated with other micropollutants that also occur in hospital effluent and that are not removed in the wastewater treatment process, including pharmaceuticals in the form of steroids, antihistamines, and antibiotics. Estuaries serve as many important ecological roles and have been shown to act as a filter for pollutants. To better understand the transport, biogeochemical cycling, and ultimate fate of trace elements in estuaries, I collected surface water samples from Bayou Bienvenue, a wetland triangle that covers an area of 427 acres directly adjacent to New Orleans, Louisiana. Water samples from Bayou Bienvenue were collected along the salinity gradient and subsequently filtered through progressively smaller pore-size filters. The resulting fractions were analyzed for trace element concentions, including the REEs, by magnetic sector ICP-MS. The attached figure shows the Gd anomaly present in the particulate (>0.45?m) fraction. Upper continental crust (UCC)-normalized plots of colloidal REEs (0.02?m - 0.45?m) fraction is lacking this anomaly indicating anthropogenic Gd is found chiefly in the particulate fraction in Bayou Bienvenue. No clear relationship between Gd concentration and salinity was apparent.

  10. The chemistry of rare earth elements in the solar nebula

    NASA Technical Reports Server (NTRS)

    Larimer, J. W.; Bartholomay, H. A.; Fegley, B.

    1984-01-01

    The high concentration of rare earth elements (REE) in primitive CaS suggests that the REE along with the other normally lithophile elements form stable sulfides under the unusual conditions which existed during the formation of enstatite chrondites. In order to acquire a more quantitative framework in which to interpret these data, the behavior of the REE in systems with solar, or slightly fractionated solar, composition is being studied. These new data introduce modest changes in the behavior of some of the REE when compared to previous studies. For example, the largest differences are in the stabilities of the gaseous monoxides of Ce, Eu, Tb, Ho, and Tm, all of which now appear to be less stable than previously thought, and YbO(g) which is somewhat more stable. Much more significant are the changes in REE distribution in the gas phase in fractionated systems, especially those made more reducing by changing the C/O ratio from the solar value of 0.6 to about 1.0. In almost all cases, the exceptions being Eu, Tm and Yb whose elemental gaseous species dominate, the monosulfides become more abundant. Moreover, the solid oxides of Eu, Tm and Yb become less stable under more reducing conditions which, in effect, should reduce the condensation temperature of all REE in more reduced systems.

  11. Rare earth elements in river waters

    NASA Technical Reports Server (NTRS)

    Goldstein, Steven J.; Jacobsen, Stein B.

    1988-01-01

    To characterize the input to the oceans of rare earth elements (REE) in the dissolved and the suspended loads of rivers, the REE concentrations were measured in samples of Amazon, Indus, Mississippi, Murray-Darling, and Ohio rivers and in samples of smaller rivers that had more distinct drainage basin lithology and water chemistry. It was found that, in the suspended loads of small rivers, the REE pattern was dependent on drainage basin geology, whereas the suspended loads in major rivers had relatively uniform REE patterns and were heavy-REE depleted relative to the North American Shale composite (NASC). The dissolved loads in the five major rivers had marked relative heavy-REE enrichments, relative to the NASC and the suspended material, with the (La/Yb)N ratio of about 0.4 (as compared with the ratio of about 1.9 in suspended loads).

  12. Experimentally determined Si isotope fractionation between silicate and Fe metal and implications for Earth's core formation

    NASA Astrophysics Data System (ADS)

    Shahar, Anat; Ziegler, Karen; Young, Edward D.; Ricolleau, Angele; Schauble, Edwin A.; Fei, Yingwei

    2009-10-01

    Stable isotope fractionation amongst phases comprising terrestrial planets and asteroids can be used to elucidate planet-forming processes. To date, the composition of the Earth's core remains largely unknown though cosmochemical and geophysical evidence indicates that elements lighter than iron and nickel must reside there. Silicon is often cited as a light element that could explain the seismic properties of the core. The amount of silicon in the core, if any, can be deduced from the difference in 30Si/ 28Si between meteorites and terrestrial rocks if the Si isotope fractionation between silicate and Fe-rich metal is known. Recent studies (e.g., [Georg R.B., Halliday A.N., Schauble E.A., Reynolds B.C., 2007. Silicon in the Earth's core. Nature 447 (31), 1102-1106.]; [Fitoussi, C., Bourdon, B., Kleine, T., Oberli, F., Reynolds, B. C., 2009. Si isotope systematics of meteorites and terrestrial peridotites: implications for Mg/Si fractionation in the solar nebula and for Si in the Earth's core. Earth Planet. Sci. Lett. 287, 77-85.]) showing (sometimes subtle) differences between 30Si/ 28Si in meteorites and terrestrial rocks suggest that Si missing from terrestrial rocks might be in the core. However, any conclusion based on Earth-meteorite comparisons depends on the veracity of the 30Si/ 28Si fractionation factor between silicates and metals at appropriate conditions. Here we present the first direct experimental evidence that silicon isotopes are not distributed uniformly between iron metal and rock when equilibrated at high temperatures. High-precision measurements of the silicon isotope ratios in iron-silicon alloy and silicate equilibrated at 1 GPa and 1800 °C show that Si in silicate has higher 30Si/ 28Si than Si in metal, by at least 2.0‰. These findings provide an experimental foundation for using isotope ratios of silicon as indicators of terrestrial planet formation processes. They imply that if Si isotope equilibrium existed during segregation of Earth's core-forming metal and silicate mantle, there should be an isotopic signature of Si in the core. Our experiments, combined with previous measurements of Si isotope ratios in meteorites and rocks representing the bulk silicate Earth, suggest that the formation of the Earth's core imparted a high 30Si/ 28Si signature to the bulk silicate Earth due to dissolution of ~ 6 wt% Si into the early core.

  13. Biogeochemistry of the rare-earth elements with particular reference to hickory trees

    USGS Publications Warehouse

    Robinson, W.O.; Bastron, H.; Murata, K.J.

    1958-01-01

    Hickory trees concentrate the rare-earth elements in their leaves to a phenomenal degree and may contain as much as 2300 p.p.m. of total rare earths based on the dry weight of the leaves. The average proportions of the individual elements (atomic percent of the total rare-earth elements) in the leaves are: Y 36, La 16, Ce 14, Pr 2, Nd 20, Sm 1, Eu 0.7, Gd 3, Tb 0.6, Dy 3, Ho 0.7, Er 2, Tm 0.2, Yb 1, and Lu 0.2. The similarity in the proportions of the rare-earth elements in the leaves and in the exchange complex of the soil on which the hickory trees grow indicates that the trees do not fractionate the rare earths appreciably. The variation of the rare-earth elements in the leaves and soils can be explained generally in terms of the relative abundance of the cerium group and the yttrium group, except for the element cerium. The large fluctuations in the proportion of cerium [Ce/(La + Nd) atomic ratios of 0.16 to 0.86] correlate with oxidation-reduction conditions in the soil profile. The substitution of dilute H2SO3 for dilute HC1 in the determination of available rare-earth elements brings about a large increase in the proportion of cerium that is extracted from an oxygenated subsoil. These relationships strongly suggest that quadrivalent cerium is present in oxygenated subsoil and is less available to plants than the other rare-earth elements that do not undergo such a change in valence. A few parts per billion of rare-earth elements have been detected in two samples of ground water. ?? 1958.

  14. Normalized rare earth elements in water, sediments, and wine: identifying sources and environmental redox conditions

    USGS Publications Warehouse

    Piper, David Z.; Bau, Michael

    2013-01-01

    The concentrations of the rare earth elements (REE) in surface waters and sediments, when normalized on an element-by-element basis to one of several rock standards and plotted versus atomic number, yield curves that reveal their partitioning between different sediment fractions and the sources of those fractions, for example, between terrestrial-derived lithogenous debris and seawater-derived biogenous detritus and hydrogenous metal oxides. The REE of ancient sediments support their partitioning into these same fractions and further contribute to the identification of the redox geochemistry of the sea water in which the sediments accumulated. The normalized curves of the REE that have been examined in several South American wine varietals can be interpreted to reflect the lithology of the bedrock on which the vines may have been grown, suggesting limited fractionation during soil development.

  15. Earth, Air, Fire and Water in Our Elements

    ERIC Educational Resources Information Center

    Lievesley, Tara

    2007-01-01

    The idea that everything is made of the four "elements", earth, air, fire and water, goes back to the ancient Greeks. In this article, the author talks about the origins of ideas about the elements. The author provides an account that attempts to summarise thousands of years of theoretical development of the elements in a thousand words or so.

  16. Fractional advection-dispersion equations for modeling transport at the Earth surface

    E-print Network

    Meerschaert, Mark M.

    Fractional advection-dispersion equations for modeling transport at the Earth surface Rina Schumer on the Earth surface is a key ingredient in describing landscape evolution. We seek equations that capture. Baeumer (2009), Fractional advection-dispersion equations for modeling transport at the Earth surface, J

  17. Core-Mantle Partitioning of Volatile Elements and the Origin of Volatile Elements in Earth and Moon

    NASA Technical Reports Server (NTRS)

    Righter, Kevin; Pando, K.; Danielson, L.; Nickodem, K.

    2014-01-01

    Depletions of volatile siderophile elements (VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd) in mantles of Earth and Moon, constrain the origin of volatile elements in these bodies, and the overall depletion of volatile elements in Moon relative to Earth. A satisfactory explanation has remained elusive [1,2]. We examine the depletions of VSE in Earth and Moon and quantify the amount of depletion due to core formation and volatility of potential building blocks. We calculate the composition of the Earth's PUM during continuous accretion scenarios with constant and variable fO2. Results suggest that the VSE can be explained by a rather simple scenario of continuous accretion leading to a high PT metal-silicate equilibrium scenario that establishes the siderophile element content of Earth's PUM near the end of accretion [3]. Core formation models for the Moon explain most VSE, but calculated contents of In, Sn, and Zn (all with Tc < 750 K) are all still too high after core formation, and must therefore require an additional process to explain the depletions in the lunar mantle. We discuss possible processes including magmatic degassing, evaporation, condensation, and vapor-liquid fractionation in the lunar disk.

  18. Investigating Rare Earth Element Systematics in the Marcellus Shale

    NASA Astrophysics Data System (ADS)

    Yang, J.; Torres, M. E.; Kim, J. H.; Verba, C.

    2014-12-01

    The lanthanide series of elements (the 14 rare earth elements, REEs) have similar chemical properties and respond to different chemical and physical processes in the natural environment by developing unique patterns in their concentration distribution when normalized to an average shale REE content. The interpretation of the REE content in a gas-bearing black shale deposited in a marine environment must therefore take into account the paleoredox conditions of deposition as well as any diagenetic remobilization and authigenic mineral formation. We analyzed 15 samples from a core of the Marcellus Shale (Whipkey ST1, Greene Co., PA) for REEs, TOC, gas-producing potential, trace metal content, and carbon isotopes of organic matter in order to determine the REE systematics of a black shale currently undergoing shale gas development. We also conducted a series of sequential leaching experiments targeting the phosphatic fractions in order to evaluate the dominant host phase of REEs in a black shale. Knowledge of the REE system in the Marcellus black shale will allow us to evaluate potential REE release and behavior during hydraulic fracturing operations. Total REE content of the Whipkey ST1 core ranged from 65-185 ?g/g and we observed three distinct REE shale-normalized patterns: middle-REE enrichment (MREE/MREE* ~2) with heavy-REE enrichment (HREE/LREE ~1.8-2), flat patterns, and a linear enrichment towards the heavy-REE (HREE/LREE ~1.5-2.5). The MREE enrichment occurred in the high carbonate samples of the Stafford Member overlying the Marcellus Formation. The HREE enrichment occurred in the Union Springs Member of the Marcellus Formation, corresponding to a high TOC peak (TOC ~4.6-6.2 wt%) and moderate carbonate levels (CaCO3 ~4-53 wt%). Results from the sequential leaching experiments suggest that the dominant host of the REEs is the organic fraction of the black shale and that the detrital and authigenic fractions have characteristic MREE enrichments. We present our conclusions on the impact of depositional setting and diagenetic remobilization and authigenic mineral formation on the REE system in the Marcellus Shale.

  19. MaRGEE: Move and Rotate Google Earth Elements

    NASA Astrophysics Data System (ADS)

    Dordevic, Mladen M.; Whitmeyer, Steven J.

    2015-12-01

    Google Earth is recognized as a highly effective visualization tool for geospatial information. However, there remain serious limitations that have hindered its acceptance as a tool for research and education in the geosciences. One significant limitation is the inability to translate or rotate geometrical elements on the Google Earth virtual globe. Here we present a new JavaScript web application to "Move and Rotate Google Earth Elements" (MaRGEE). MaRGEE includes tools to simplify, translate, and rotate elements, add intermediate steps to a transposition, and batch process multiple transpositions. The transposition algorithm uses spherical geometry calculations, such as the haversine formula, to accurately reposition groups of points, paths, and polygons on the Google Earth globe without distortion. Due to the imminent deprecation of the Google Earth API and browser plugin, MaRGEE uses a Google Maps interface to facilitate and illustrate the transpositions. However, the inherent spatial distortions that result from the Google Maps Web Mercator projection are not apparent once the transposed elements are saved as a KML file and opened in Google Earth. Potential applications of the MaRGEE toolkit include tectonic reconstructions, the movements of glaciers or thrust sheets, and time-based animations of other large- and small-scale geologic processes.

  20. Modeling rammed earth wall using discrete element method

    NASA Astrophysics Data System (ADS)

    Bui, T.-T.; Bui, Q.-B.; Limam, A.; Morel, J.-C.

    2015-07-01

    Rammed earth is attracting renewed interest throughout the world thanks to its "green" characteristics in the context of sustainable development. Several research studies have thus recently been carried out to investigate this material. Some of them attempted to simulate the rammed earth's mechanical behavior by using analytical or numerical models. Most of these studies assumed that there was a perfect cohesion at the interface between earthen layers. This hypothesis proved to be acceptable for the case of vertical loading, but it could be questionable for horizontal loading. To address this problem, discrete element modeling seems to be relevant to simulate a rammed earth wall. To our knowledge, no research has been conducted thus far using discrete element modeling to study a rammed earth wall. This paper presents an assessment of the discrete element modeling's robustness for rammed earth walls. Firstly, a brief description of the discrete element modeling is presented. Then the parameters necessary for discrete element modeling of the material law of the earthen layers and their interfaces law following the Mohr-Coulomb model with a tension cut-off and post-peak softening were given. The relevance of the model and the material parameters were assessed by comparing them with experimental results from the literature. The results showed that, in the case of vertical loading, interfaces did not have an important effect. In the case of diagonal loading, model with interfaces produced better results. Interface characteristics can vary from 85 to 100% of the corresponding earthen layer's characteristics.

  1. Rare earth elements in scleractinian cold-water corals

    NASA Astrophysics Data System (ADS)

    Raddatz, J.; Liebetrau, V.; Hathorne, E. C.; Rüggeberg, A.; Dullo, W.; Frank, M.

    2012-12-01

    The Rare Earth Elements (REE) have a great potential to trace continental input, particle scavenging and the oxidation state of seawater. These REE are recorded in the skeleton of the cosmopolitan cold-water corals Lophelia pertusa. Here we use an online preconcentration ICP-MS method (Hathorne et al. 2012) to measure REE concentrations in seawater and associated cold-water coral carbonates in order to investigate their seawater origin. Scleractinian cold-water corals were collected in-situ and alive and with corresponding seawater samples covering from the European Continental Margin. The seawater REE patterns are characterized by the typical negative cerium anomaly of seawater, but are distinct for the northern Norwegian Margin and the Oslo Fjord, probably related to continental input. Initial results for the corresponding coral samples suggest that these distinct REE patterns of ambient seawater are recorded by the coral skeletons although some fractionation during incorporation into the aragonite occurs. This indicates that scleractinian cold-water corals can serve as a valuable archive for seawater derived REE signatures, as well radiogenic Nd isotope compositions. In a second step we analysed fossil coral samples from various locations, which were oxidatively and reductively cleaned prior to analysis. Initial results reveal that sediment-buried fossil (early Pleistocene to Holocene) coral samples from the Norwegian Margin and the Porcupine Seabight (Challenger Mound, IODP Site 1317) do not show the expected seawater REE patterns. In particular, the fossil coral-derived REE patterns lack a negative cerium anomaly suggesting that fossil coral-REE patterns do not represent ambient seawater. Thus, we suggest that the oxidative-reductive cleaning method widely used for cleaning of marine carbonates such as foraminifera prior to measurements of seawater-derived trace metal and isotope compositions are not sufficient for REE and Nd isotopes in sediment-buried coral-water corals and require alternative or additional approaches. Hathorne, E.C., B. Haley, T. Stichel, P. Grasse, M. Zieringer, and M. Frank (2012). Online preconcentration ICP-MS analysis of rare earth elements in seawater, Geochem. Geophys. Geosyst.,13, Q01020, doi:10.1029/2011GC003907. .

  2. Rare earth elements and neodymium isotopes in sedimentary organic matter

    NASA Astrophysics Data System (ADS)

    Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

    2014-09-01

    We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ?REE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display ?Nd values that typically range between the ?Nd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter (inferred from the analysis of local surface seawater). A notable exception is the case of organic matter (OM) fractions leached from cold seep sediment samples, which sometimes exhibit ?Nd values markedly different from both terrigenous and surface seawater signatures. This suggests that a significant fraction of organic compounds in these sediments may be derived from chemosynthetic processes, recycling pore water REE characterized by a distinct isotopic composition. Overall, our results confirm that organic matter probably plays an important role in the oceanic REE budget, through direct scavenging and remineralization within the water column. Both the high REE abundances and the shape of shale-normalized patterns for leached SOM also suggest that OM degradation in sub-surface marine sediments during early diagenesis could control, to a large extent, the distribution of REE in pore waters. Benthic fluxes of organic-bound REE could hence substantially contribute to the exchange processes between particulates and seawater that take place at ocean margins. Neodymium isotopes could provide useful information for tracing the origin (terrestrial versus marine) and geographical provenance of organic matter, with potential applications in paleoceanography. In particular, future studies should further investigate the potential of Nd isotopes in organic compounds preserved in sedimentary records for reconstructing past variations of surface ocean circulation.

  3. Determination of thorium and of rare earth elements in cerium earth minerals and ores

    USGS Publications Warehouse

    Carron, M.K.; Skinner, D.L.; Stevens, R.E.

    1955-01-01

    The conventional oxalate method for precipitating thorium and the rare earth elements in acid solution exhibits definite solubilities of these elements. The present work was undertaken to establish conditions overcoming these solubilities and to find optimum conditions for precipitating thorium and the rare earth elements as hydroxides and sebacates. The investigations resulted in a reliable procedure applicable to samples in which the cerium group elements predominate. The oxalate precipitations are made from homogeneous solution at pH 2 by adding a prepared solution of anhydrous oxalic acid in methanol instead of the more expensive crystalline methyl oxalate. Calcium is added as a carrier. Quantitative precipitation of thorium and the rare earth elements is ascertained by further small additions of calcium to the supernatant liquid, until the added calcium precipitates as oxalate within 2 minutes. Calcium is removed by precipitating the hydroxides of thorium and rare earths at room temperature by adding ammonium hydroxide to pH > 10. Thorium is separated as the sebacate at pH 2.5, and the rare earths are precipitated with ammonium sebacate at pH 9. Maximum errors for combined weights of thorium and rare earth oxides on synthetic mixtures are ??0.6 mg. Maximum error for separated thoria is ??0.5 mg.

  4. ?-decay of neutron-rich Z?60 nuclei and the origin of rare earth elements

    SciTech Connect

    Wu, J.; Nishimura, S.; Lorusso, G.; Baba, H.; Doornenbal, P.; Isobe, T.; Söderström, P. A.; Sakurai, H.; Xu, Z. Y.; Browne, F.; Daido, R.; Fang, Y. F.; Yagi, A.; Nishibata, H.; Odahara, A.; Yamamoto, T.; Ideguchi, E.; Aoi, N.; Tanaka, M.; Collaboration: EURICA Collaboration; and others

    2014-05-02

    A large fraction of the rare-earth elements observed in the solar system is produced in the astrophysical rapid neutron capture process (r-process). However, current stellar models cannot completely explain the relative abundance of these elements partially because of nuclear physics uncertainties. To address this problem, a ?-decay spectroscopy experiment was performed at RI Beam Factory (RIBF) at RIKEN, aimed at studying a wide range of very neutron-rich nuclei with Z?60 that are progenitors of the rare-earth elements with mass number A?460. The experiment provides a test of nuclear models as well as experimental inputs for r-process calculations. This contribution presents the experimental setup and some preliminary results of the experiment.

  5. Biologically mediated isotope fractionations - Biochemistry, geochemical significance and preservation in the earth's oldest sediments

    NASA Technical Reports Server (NTRS)

    Schidlowski, M.

    1983-01-01

    Preferential metabolization of isotopically light carbon and sulfur has resulted in a fractionation of the stable isotopes of these elements on a global scale, with the light species (C-12, S-32) markedly concentrated in biogenic materials. Since the biological effects are basically retained when carbon and sulfur are incorporated in sediments, the respective fractionations are propagated into the rock section of the geochemical cycle, this having consequently caused a characteristic bipartition of both elements between 'light' and 'heavy' crustal reservoirs. Preservation of the biological isotope effects in sedimentary rocks makes it possible to trace the underlying biochemical processes back over most of the geological record. According to the available evidence, biological (autotrophic) carbon fixation arose prior to 3.5(if not 3.8) billion years ago, while the emergence of dissimilatory sulfate reduction antedates the appearance of the oldest presumably bacteriogenic sulfur isotope patterns in rocks between 2.7 and 2.8 billion years old. Hence, biological control of the terrestrial carbon and sulfur cycles has been established very early in the earth's history.

  6. Multi-objective optimization of chromatographic rare earth element separation.

    PubMed

    Knutson, Hans-Kristian; Holmqvist, Anders; Nilsson, Bernt

    2015-10-16

    The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium. PMID:26375205

  7. Biological availability and environmental behaviour of Rare Earth Elements in soils of Hesse, Central Germany

    NASA Astrophysics Data System (ADS)

    Loell, M.; Duering, R.-A.; Felix-Henningsen, P.

    2009-04-01

    Rare earth elements (REEs) comprise a group of 17 transition metals with very similar chemical and physical properties. They include the elements scandium (Sc), yttrium (Y) and lanthanum (La) and the 14 elements (cerium to lutetium) that follow La in the periodic table. Their average abundance in the earth's crust varies from 0,01 to 0,02% so they are as common as Cu and Pb. Beside their widespread use in industry, REEs are applied in Chinese agriculture. Their beneficial effects both on crop yield and on animal production are reported in various investigations. As a result - by using microelement fertilisers and manure - REEs enter the pedosphere while their fate and behaviour in the environment up to now remains unexamined. The first aim of our investigation was to evaluate the concentration of REEs in agricultural used soils in central Germany (Hesse) by ICP-MS. In addition to their total concentration (aqua regia digestion) their bioavailable contents - determined by EDTA (potentially available fraction) and ammonium nitrate extraction (mobile fraction) - were analysed. The occurrence of the three REE fractions in different soils will be discussed and influencing soil properties (e.g. pH-value, content of clay and organic carbon) will be revealed. Additionally the uptake of REEs by grassland plants was determined and resulting transfer factors will be presented.

  8. Coal fly ash as a resource for rare earth elements.

    PubMed

    Franus, Wojciech; Wiatros-Motyka, Ma?gorzata M; Wdowin, Magdalena

    2015-06-01

    Rare earth elements (REE) have been recognised as critical raw materials, crucial for many clean technologies. As the gap between their global demand and supply increases, the search for their alternative resources becomes more and more important, especially for the countries which depend highly on their import. Coal fly ash (CFA), which when not utilised is considered waste, has been regarded as the possible source of many elements, including REE. Due to the increase in the energy demand, CFA production is expected to grow, making research into the use of this material a necessity. As Poland is the second biggest coal consumer in the European Union, the authors have studied different coal fly ashes from ten Polish power plants for their rare earth element content. All the fly ashes have a broadly similar distribution of rear earth elements, with light REE being dominant. Most of the samples have REE content relatively high and according to Seredin and Dai (Int J Coal Geol 94: 67-93, 2012) classification can be considered promising REE raw materials. PMID:25613802

  9. Uncovering the end uses of the rare earth elements.

    PubMed

    Du, Xiaoyue; Graedel, T E

    2013-09-01

    The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging and conventional established technologies. However, quantitative knowledge of REE remains sparse, despite the current heightened interest in future availability of the resources. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supply vulnerable to short term disruption. We have drawn upon the published literature and unpublished materials in different languages to derive the first quantitative annual domestic production by end use of individual rare earth elements from 1995 to 2007. The information is illustrated in Sankey diagrams for the years 1995 and 2007. Other years are available in the supporting information. Comparing 1995 and 2007, the production of the rare earth elements in China, Japan, and the US changed dramatically in quantities and structure. The information can provide a solid foundation for industries, academic institutions and governments to make decisions and develop strategies. PMID:23602698

  10. Compositional and phase relations among rare earth element minerals

    NASA Technical Reports Server (NTRS)

    Burt, D. M.

    1990-01-01

    This paper discusses the compositional and phase relationships among minerals in which rare earth elements (REE) occur as essential constituents (e.g., bastnaesite, monazite, xenotime, aeschynite, allanite). Particular consideration is given to the vector representation of complex coupled substitutions in selected REE-bearing minerals and to the REE partitioning between minerals as related to the acid-base tendencies and mineral stabilities. It is shown that the treatment of coupled substitutions as vector quantities facilitates graphical representation of mineral composition spaces.

  11. The Oceanic Chemistry of the Rare-Earth Elements

    NASA Astrophysics Data System (ADS)

    Elderfield, H.

    1988-05-01

    Because of the unique chemical characteristics of the rare-earth elements (REES), they provide information as oceanic tracers of element source and reactivity. The absolute and relative concentrations of the REES in ocean waters reflect their input from rivers, by aeolian transport and from hydrothermal vents; their interaction with the bio-geochemical cycle involving removal from surface waters by adsorption and oxidation at particle surfaces (probably with organic coatings) and deeper regeneration; and the effects of advective transport. Within the REE group, Ce anomalies occur in response to oceanic redox conditions; Eu anomalies in response to aeolian and hydrothermal input; and Nd isotopic variations reflect element sources. Both REE concentration patterns and Nd isotopic variations allow the effects of the vertical particle flux and of lateral advection to be separated.

  12. Uncovering the Global Life Cycles of the Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Du, Xiaoyue; Graedel, T. E.

    2011-11-01

    The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging, critical technologies. Knowledge of the life cycles of REE remains sparse, despite the current heightened interest in their future availability. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supplies vulnerable to short and long-term disruption. To provide an improved perspective we derived the first quantitative life cycles (for the year 2007) for ten REE: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), and yttrium (Y). Of these REE, Ce and Nd in-use stocks are highest; the in-use stocks of most REE show significant accumulation in modern society. Industrial scrap recycling occurs only from magnet manufacture. We believe there is no post-customer recycling of any of these elements.

  13. Anthropogenic Disturbance of Element Cycles at the Earth's Surface

    NASA Astrophysics Data System (ADS)

    Sen, I. S.; Peucker-Ehrenbrink, B.

    2012-12-01

    The extent to which humans are modifying Earth's surface chemistry can be quantified by comparing total anthropogenic element fluxes with their natural counterparts [1]. We determine anthropogenic mass transfer of 77 elements from mining, fossil fuel burning, biomass burning, construction activities, and human apportionment of terrestrial net primary productivity, and compared it to natural mass transfer from terrestrial and marine net primary productivity, riverine dissolved and suspended matter fluxes to the ocean, soil erosion, eolian dust, sea-salt spray, cosmic dust, volcanic emissions and - for helium - hydrodynamic escape from the Earth's atmosphere. In addition, we introduce an approach to correct for losses during industrial processing of elements belonging to geochemically coherent groups, and explicitly incorporated uncertainties of element mass fluxes through Monte Carlo simulations [2]. Our assessment indicates that anthropogenic fluxes of iridium, osmium, helium, gold, ruthenium, antimony, platinum, palladium, rhenium, rhodium and chromium are greater than the respective natural fluxes. For these elements mining is the major factor of human dominance, whereas petroleum burning strongly influence the surficial cycle of rhenium. Apart from these 11 elements there are 15 additional elements whose anthropogenic fluxes may surpass their corresponding natural fluxes. Anthropogenic fluxes of the remaining elements are smaller than their corresponding natural fluxes although a significant human influence is observed for all of them. For example, ~20% of the annual fluxes of C, N, and P can be attributed to human activities. Such disturbances, though small compared with natural fluxes, can significantly alter concentrations in near-surface reservoirs and affect ecosystems if they are sustained over time scales similar to or longer than the residence time of elements in the respective reservoir. Examples are the continuing input of CO2 to the atmosphere that has led to a 40% increase in atmospheric CO2 concentrations, and the atmospheric redistribution of reactive nitrogen and accumulation in remote ecosystems. We note that if anthropogenic contributions to soil erosion and eolian dust are considered, anthropogenic fluxes of up to 62 elements may surpass their corresponding natural fluxes. [1] Klee and Graedel (2004), Annu. Rev. Environ. Resour., 29, p. 69-107 [2] Sen and Peucker-Ehrenbrink (2012), Environ. Sci. Technol., dx.doi.org/10.1021/es301261x

  14. The Earth Based Ground Stations Element of the Lunar Program

    NASA Technical Reports Server (NTRS)

    Gal-Edd, Jonathan; Fatig, Curtis; Schier, James; Lee, Charles

    2007-01-01

    The Lunar Architecture Team (LAT) is responsible for developing a concept for building and supporting a lunar outpost with several exploration capabilities such as rovers, colonization, and observatories. The lunar outpost is planned to be located at the Moon's South Pole. The LAT Communications and Navigation Team (C&N) is responsible for defining the network infrastructure to support the lunar outpost. The following elements are needed to support lunar outpost activities: A Lunar surface network based on industry standard wireless 802.xx protocols, relay satellites positioned 180 degrees apart to provide South Pole coverage for the half of the lunar 28-day orbit that is obscured from Earth view, earth-based ground stations deployed at geographical locations 120 degrees apart. This paper will focus on the Earth ground stations of the lunar architecture. Two types of ground station networks are discussed. One provides Direct to Earth (DTE) support to lunar users using Kaband 23/26Giga-Hertz (GHz) communication frequencies. The second supports the Lunar Relay Satellite (LRS) that will be using Ka-band 40/37GHz (Q-band). This paper will discuss strategies to provide a robust operational network in support of various lunar missions and trades of building new antennas at non-NASA facilities, to improve coverage and provide site diversification for handling rain attenuation.

  15. Assessing rare earth elements in quartz rich geological samples.

    PubMed

    Santoro, A; Thoss, V; Ribeiro Guevara, S; Urgast, D; Raab, A; Mastrolitti, S; Feldmann, J

    2016-01-01

    Sodium peroxide (Na2O2) fusion coupled to Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) measurements was used to rapidly screen quartz-rich geological samples for rare earth element (REE) content. The method accuracy was checked with a geological reference material and Instrumental Neutron Activation Analysis (INAA) measurements. The used mass-mode combinations presented accurate results (only exception being (157)Gd in He gas mode) with recovery of the geological reference material QLO-1 between 80% and 98% (lower values for Lu, Nd and Sm) and in general comparable to INAA measurements. Low limits of detection for all elements were achieved, generally below 10pgg(-1), as well as measurement repeatability below 15%. Overall, the Na2O2/ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare earth element content; particularly useful if checking commercial viability. PMID:26595776

  16. Compositional and phase relations among rare earth element minerals

    NASA Technical Reports Server (NTRS)

    Burt, D. M.

    1989-01-01

    A review is presented that mainly treats minerals in which the rare-earth elements are essential constituents, e.g., bastnaesite, monazite, xenotime, aeschynite, allanite. The chemical mechanisms and limits of REE substitution in some rock-forming minerals (zircon, apatite, titanite, garnet) are also derived. Vector representation of complex coupled substitutions in selected REE-bearing minerals is examined and some comments on REE-partitioning between minerals as related to acid-based tendencies and mineral stabilities are presented. As the same or analogous coupled substitutions involving the REE occur in a wide variety of mineral structures, they are discussed together.

  17. Determination of rare earth elements in high purity rare earth oxides by liquid chromatography, thermionic mass spectrometry and combined liquid chromatography/thermionic mass spectrometry

    NASA Astrophysics Data System (ADS)

    Stijfhoorn, D. E.; Stray, H.; Hjelmseth, H.

    1993-03-01

    A high-performance liquid Chromatographie (HPLC) method for the determination of rare earth elements in rocks has been modified and used for the determination of rare earth elements (REE) in high purity rare earth oxides. The detection limit was 1-1.5 ng or 2-3 mg/kg when a solution corresponding to 0.5 mg of the rare earth oxide was injected. The REE determination was also carried out by adding a mixture of selected REE isotopes to the sample and analysing the collected HPLC-fractions by mass spectrometry (MS) using a thermionic source. Since the matrix element was not collected, interference from this element during the mass spectrometric analysis was avoided. Detection limits as low as 0.5 mg/kg could then be obtained. Detection limits as low as 0.05 mg/kg were possible by MS without HPLC-pre-separation, but this approach could only be used for those elements that were not affected by the matrix. Commercial samples of high purity Nd 2O 3, Gd 2O 3 and Dy 2O 3 were analysed in this study, and a comparison of results obtained by HPLC, combined HPLC/MS and direct MS are presented.

  18. Trace Elemental Imaging of Rare Earth Elements Discriminates Tissues at Microscale in Flat Fossils

    PubMed Central

    Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B.; Cohen, Serge X.; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc

    2014-01-01

    The interpretation of flattened fossils remains a major challenge due to compression of their complex anatomies during fossilization, making critical anatomical features invisible or hardly discernible. Key features are often hidden under greatly preserved decay prone tissues, or an unpreparable sedimentary matrix. A method offering access to such anatomical features is of paramount interest to resolve taxonomic affinities and to study fossils after a least possible invasive preparation. Unfortunately, the widely-used X-ray micro-computed tomography, for visualizing hidden or internal structures of a broad range of fossils, is generally inapplicable to flattened specimens, due to the very high differential absorbance in distinct directions. Here we show that synchrotron X-ray fluorescence spectral raster-scanning coupled to spectral decomposition or a much faster Kullback-Leibler divergence based statistical analysis provides microscale visualization of tissues. We imaged exceptionally well-preserved fossils from the Late Cretaceous without needing any prior delicate preparation. The contrasting elemental distributions greatly improved the discrimination of skeletal elements material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline earth elements and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare earth elements. Local quantification of rare earths may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies. PMID:24489809

  19. Rare earth elements and neodymium isotopes in world river sediments revisited

    NASA Astrophysics Data System (ADS)

    Bayon, G.; Toucanne, S.; Skonieczny, C.; André, L.; Bermell, S.; Cheron, S.; Dennielou, B.; Etoubleau, J.; Freslon, N.; Gauchery, T.; Germain, Y.; Jorry, S. J.; Ménot, G.; Monin, L.; Ponzevera, E.; Rouget, M.-L.; Tachikawa, K.; Barrat, J. A.

    2015-12-01

    Over the past decades, rare earth elements (REE) and their radioactive isotopes have received tremendous attention in sedimentary geochemistry, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on elemental concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world's major rivers. Sediments were leached for removal of non-detrital components, and both clay and silt fractions were retained for separate geochemical analyses. Our aim was to re-examine, at the scale of a large systematic survey, whether or not REE and Nd isotopes could be fractionated during Earth surface processes. Our results confirmed earlier assumptions that river sediments do not generally exhibit any significant grain-size dependent Nd isotopic variability. Most sediments from rivers draining old cratonic areas, sedimentary systems and volcanic provinces displayed similar Nd isotopic signatures in both clay and silt fractions, with ??Nd(clay-silt) < |1|. A subtle decoupling of Nd isotopes between clays and silts was identified however in a few major river systems (e.g. Nile, Mississippi, Fraser), with clays being systematically shifted towards more radiogenic values. This observation suggests that preferential weathering of volcanic and/or sedimentary rocks relative to more resistant lithologies may occur in river basins, possibly leading locally to Nd isotopic decoupling between different size fractions. Except for volcanogenic sediments, silt fractions generally displayed homogeneous REE concentrations, exhibiting relatively flat shale-normalized patterns. However, clay fractions were almost systematically characterized by a progressive enrichment from the heavy to the light REE and a positive europium (Eu) anomaly. In agreement with results from previous soil investigations, the observed REE fractionation between clays and silts is probably best explained by preferential alteration of feldspars and/or accessory mineral phases. Importantly, this finding clearly indicates that silicate weathering can lead to decoupling of REE between different grain-size fractions, with implications for sediment provenance studies. Finally, we propose a set of values for a World River Average Clay (WRAC) and Average Silt (WRAS), which provide new estimates for the average composition of the weathered and eroded upper continental crust, respectively, and could be used for future comparison purposes.

  20. Rare earth elements in the phosphatic-enriched sediment of the Peru shelf

    USGS Publications Warehouse

    Piper, D.Z.; Baedecker, P.A.; Crock, J.G.; Burnett, W.C.; Loebner, B.J.

    1988-01-01

    Apatite-enriched materials from the Peru shelf have been analyzed for their major oxide and rare earth element (REE) concentrations. The samples consist of (1) the fine fraction of sediment, mostly clay material, (2) phosphatic pellets and fish debris, which are dispersed throughout the fine-grained sediment, (3) tabular-shaped phosphatic crusts, which occur within the uppermost few centimeters of sediment, and (4) phosphatic nodules, which occur on the seafloor. The bulk REE concentrations of the concretions suggest that these elements are partitioned between the enclosed detrital material and the apatite fraction. Analysis of the fine-grained sediment with which the samples are associated suggested that this detrital fraction in the concretions should have shale REE values; the analysis of the fish debris suggested that the apatite fraction might have seawater values. The seawater contribution of REE's is negligible in the nodules and crust, in which the apatite occurs as a fine-grained interstitial cement. That is, the concentration of REE's and the REE patterns are predominantly a function of the amount of enclosed fine-grained sediment. By contrast, the REE pattern of the pelletal apatite suggests a seawater source and the absolute REE concentrations are relatively high. The REE P2O5 ratios of the apatite fraction of these samples thus vary from approximately zero (in the case of the crust and nodules) to as much as approximately 1.2 ?? 10-3 (in the case of the pellets). The range of this ratio suggests that rather subtle variations in the depositional environment might cause a significant variation in the REE content of this authigenic fraction of the sediment. Pelletal glauconite was also recovered from one sediment core. Its REE concentrations closely resemble those of the fish debris. ?? 1988.

  1. Mimicking the magnetic properties of rare earth elements using superatoms

    PubMed Central

    Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A. W.

    2015-01-01

    Rare earth elements (REs) consist of a very important group in the periodic table that is vital to many modern technologies. The mining process, however, is extremely damaging to the environment, making them low yield and very expensive. Therefore, mimicking the properties of REs in a superatom framework is especially valuable but at the same time, technically challenging and requiring advanced concepts about manipulating properties of atom/molecular complexes. Herein, by using photoelectron imaging spectroscopy, we provide original idea and direct experimental evidence that chosen boron-doped clusters could mimic the magnetic characteristics of REs. Specifically, the neutral LaB and NdB clusters are found to have similar unpaired electrons and magnetic moments as their isovalent REs (namely Nd and Eu, respectively), opening up the great possibility in accomplishing rare earth mimicry. Extension of the superatom concept into the rare earth group not only further shows the power and advance of this concept but also, will stimulate more efforts to explore new superatomic clusters to mimic the chemistry of these heavy atoms, which will be of great importance in designing novel building blocks in the application of cluster-assembled nanomaterials. Additionally, based on these experimental findings, a novel “magic boron” counting rule is proposed to estimate the numbers of unpaired electrons in diatomic LnB clusters. PMID:25848014

  2. Mimicking the magnetic properties of rare earth elements using superatoms.

    PubMed

    Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A W

    2015-04-21

    Rare earth elements (REs) consist of a very important group in the periodic table that is vital to many modern technologies. The mining process, however, is extremely damaging to the environment, making them low yield and very expensive. Therefore, mimicking the properties of REs in a superatom framework is especially valuable but at the same time, technically challenging and requiring advanced concepts about manipulating properties of atom/molecular complexes. Herein, by using photoelectron imaging spectroscopy, we provide original idea and direct experimental evidence that chosen boron-doped clusters could mimic the magnetic characteristics of REs. Specifically, the neutral LaB and NdB clusters are found to have similar unpaired electrons and magnetic moments as their isovalent REs (namely Nd and Eu, respectively), opening up the great possibility in accomplishing rare earth mimicry. Extension of the superatom concept into the rare earth group not only further shows the power and advance of this concept but also, will stimulate more efforts to explore new superatomic clusters to mimic the chemistry of these heavy atoms, which will be of great importance in designing novel building blocks in the application of cluster-assembled nanomaterials. Additionally, based on these experimental findings, a novel "magic boron" counting rule is proposed to estimate the numbers of unpaired electrons in diatomic LnB clusters. PMID:25848014

  3. Origin of Terrestrial Water: Hydrogen/Deuterium Fractionation into Earth's Core

    NASA Astrophysics Data System (ADS)

    Wu, J.; Buseck, P. R.

    2014-12-01

    Hydrogen isotopic compositions are among the most important constraints on the origin of Earth's water. Earth's bulk water content, which is small but not negligible, is significantly greater than what the thermal gradient of the solar nebula disk would suggest for planetesimal materials condensed at one astronomical unit. The proto-solar nebula is a likely source of early Earth's water, with probable contributions from one or more of the following: water-rich planetesimals, ordinary and carbonaceous meteorites, comets, asteroids, and interplanetary dust particles. However, all of these sources have been questioned, and the proposed proto-solar nebular origin has been disputed in light of the large difference in hydrogen isotopic composition between it and terrestrial water. Current opposition to the solar nebular hypothesis is based on the critical assumption that no processes in the interior of the early Earth changed the isotopic composition of hydrogen. Nevertheless, a hypothesized hydrogenation reaction of liquid iron (2Fe + xH2 ? 2FeHx) during core formation likely provided a fractionation mechanism between hydrogen and deuterium (D). We propose that modern D/H ratios at Earth's surface resulted from this isotopic fractionation and that terrestrial water originated from oxidation of proto-solar hydrogen dissolved in the magma ocean in the early Earth by coexisting oxides (such as FeO). Thus, the isotopic composition of water on Earth can be mainly explained by internal terrestrial processes.

  4. COLORS OF A SECOND EARTH: ESTIMATING THE FRACTIONAL AREAS OF OCEAN, LAND, AND VEGETATION OF EARTH-LIKE EXOPLANETS

    SciTech Connect

    Fujii, Yuka; Kawahara, Hajime; Suto, Yasushi; Taruya, Atsushi; Fukuda, Satoru; Nakajima, Teruyuki; Turner, Edwin L.

    2010-06-01

    Characterizing the surfaces of rocky exoplanets via their scattered light will be an essential challenge in investigating their habitability and the possible existence of life on their surfaces. We present a reconstruction method for fractional areas of different surface types from the colors of an Earth-like exoplanet. We create mock light curves for Earth without clouds using empirical data. These light curves are fitted to an isotropic scattering model consisting of four surface types: ocean, soil, snow, and vegetation. In an idealized situation where the photometric errors are only photon shot noise, we are able to reproduce the fractional areas of those components fairly well. The results offer some hope for detection of vegetation via the distinct spectral feature of photosynthesis on Earth, known as the red edge. In our reconstruction method, Rayleigh scattering due to the atmosphere plays an important role, and for terrestrial exoplanets with an atmosphere similar to our Earth, it is possible to estimate the presence of oceans and an atmosphere simultaneously.

  5. The elements of the Earth's magnetism and their secular changes between 1550 and 1915

    NASA Technical Reports Server (NTRS)

    Fritsche, H.

    1983-01-01

    The results of an investigation about the magnetic agents outside the Earth's surface as well as the Earth's magnetic elements for the epochs 1550, 1900, 1915 are presented. The secular changes of the Earth's magnetic elements during the time interval 1550 - 1900 are also included.

  6. Rare earth element systematics of fossil bone revealed by LA-ICPMS analysis

    NASA Astrophysics Data System (ADS)

    Herwartz, Daniel; Tütken, Thomas; Jochum, Klaus Peter; Sander, P. Martin

    2013-02-01

    Intra-bone rare earth element (REE) fractionation trends were studied by LA-ICPMS analysis to put constraints on (1) the mechanisms controlling REE fractionation within fossil bones; (2) the relative timing of REE uptake in various parts of fossil bone and (3) the origin of REE in fossil bones. We have evaluated REE bone profiles across 54 fossil bones from a broad range of well-characterised taphonomic settings ranging in age from Triassic to early Medieval. REE patterns and concentration gradients are highly variable and intra-bone fractionation trends in (La/Yb)N vs. (La/Sm)N space of few specimens cover almost the entire range previously observed for bulk samples. Intra-bone variability of Ce anomalies, as well as variable Y/Ho and (La/La?)N is also observed. Sometimes, diagenetic fluids with fractionated, HREE enriched compositions have entered the bone from the marrow cavity, producing secondary REE uptake profiles. Theoretical intra-bone fractionation trends, modelled using lattice strain theory, concur with most REE data but some trends cannot be modelled using realistic boundary conditions. This fact, as well as the occurence of positive and negative Ce anomalies within the same fossil sample, hint towards changing REE compositions of diagenetic fluids over the timescales of REE uptake. Because apparent Ce anomalies frequently evolve over bone profiles and Ce anomalies can be inherited from previous fractionation events, Ce anomalies are a highly ambiguous tracer for constraining ambient redox conditions. In general, bioapatite REE signatures may not always reliably reflect ambient taphonomic or redox conditions and diagenetic fluid compositions. Therefore REE patterns and Ce anomalies of fossil bones must be interpreted cautiously as they vary spatially within skeletal remains and are affected by intra-bone fractionation processes as well as changing compositions of the diagenetic fluid.

  7. 8 Sequential P Fractionation of Relict Anthropogenic Dark Earths of Amazonia

    E-print Network

    Lehmann, Johannes

    .O. Box 26416 (ICRAF/AHI), Kampala, Uganda 8.1 Introduction Dark earths which are rich in small artifacts of anthropogenic activities can be deter- mined without large excavations and provide important information even in the absence of artifacts. A sequential fractionation scheme that distinguishes between different soil P pools

  8. Insights into early Earth from Barberton komatiites: Evidence from lithophile isotope and trace element systematics

    NASA Astrophysics Data System (ADS)

    Puchtel, I. S.; Blichert-Toft, J.; Touboul, M.; Walker, R. J.; Byerly, G. R.; Nisbet, E. G.; Anhaeusser, C. R.

    2013-05-01

    Major, minor, and lithophile trace element abundances and Nd and Hf isotope systematics are reported for two sets of remarkably fresh, by Archean standards, samples of komatiitic lavas from the 3.48 Ga Komati and the 3.27 Ga Weltevreden Formations of the Barberton Greenstone Belt (BGB) in South Africa. These data are used to place new constraints on the thermal history of the early Archean mantle, on the timing of its differentiation, and on the origin and chemical nature of early mantle reservoirs and their evolution through time. Projected moderate to strong depletions of highly incompatible lithophile trace elements and water in the mantle sources of both komatiite systems, combined with the partitioning behavior of V during lava differentiation, are consistent with anhydrous conditions during generation of the komatiite magmas. Komati and Weltevreden lavas are inferred to have erupted with temperatures of ?1600 °C, and, thus, represent the hottest known lavas on Earth. The calculated mantle potential temperatures of ?1800 °C for both komatiite systems are 150-200 °C higher than those of contemporary ambient mantle. Combined, these observations are consistent with the origin of these BGB komatiite magmas in mantle plumes in the lower mantle. New Sm-Nd and Lu-Hf isotopic data allow precise determination of initial ?143Nd = +0.46 ± 0.10 and +0.50 ± 0.11 and initial ?176Hf = +1.9 ± 0.3 and +4.7 ± 0.8 for the Komati and the Weltevreden system komatiites, respectively. These positive initial values reflect prior fractionation of Sm/Nd and Lu/Hf in the mantle early in Earth history. Conversely, ?142Nd values are 0.0 ± 2.4 and +2.2 ± 4.1 for the Komati and the Weltevreden systems, respectively. These values overlap, within uncertainties, those of modern terrestrial rocks, thus, limiting the magnitudes of possible Sm/Nd fractionations generated by early Earth processes in the sources of these rocks. Combined 142,143Nd and Hf isotope and lithophile trace element systematics are consistent with formation and long-term isolation of deep-seated mantle domains with fractionated Sm/Nd and Lu/Hf at ca. 4400 Ma. These domains were likely generated as a result of crystallization of a primordial magma ocean, with Mg-perovskite and minor Ca-perovskite acting as fractionating phases. The inferred mantle domains were evidently mixed away by 2.7 Ga on the scale of mantle reservoirs sampled by late Archean komatiite lavas emplaced worldwide.

  9. Core-Mantle Partitioning of Volatile Elements and the Origin of Volatile Elements in Earth and Moon

    NASA Technical Reports Server (NTRS)

    Righter, K.; Pando, K.; Danielson, L.; Nickodem, K.

    2014-01-01

    Depletions of siderophile elements in mantles have placed constraints on the conditions on core segregation and differentiation in bodies such as Earth, Earth's Moon, Mars, and asteroid 4 Vesta. Among the siderophile elements there are a sub-set that are also volatile (volatile siderophile elements or VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd), and thus can help to constrain the origin of volatile elements in these bodies, and in particular the Earth and Moon. One of the fundamental observations of the geochemistry of the Moon is the overall depletion of volatile elements relative to the Earth, but a satisfactory explanation has remained elusive. Hypotheses for Earth include addition during accretion and core formation and mobilized into the metallic core, multiple stage origin, or addition after the core formed. Any explanation for volatile elements in the Earth's mantle must also be linked to an explanation of these elements in the lunar mantle. New metal-silicate partitioning data will be applied to the origin of volatile elements in both the Earth and Moon, and will evaluate theories for exogenous versus endogenous origin of volatile elements.

  10. Online preconcentration ICP-MS analysis of rare earth elements in seawater

    NASA Astrophysics Data System (ADS)

    Hathorne, Ed C.; Haley, Brian; Stichel, Torben; Grasse, Patricia; Zieringer, Moritz; Frank, Martin

    2012-01-01

    The rare earth elements (REEs) with their systematically varying properties are powerful tracers of continental inputs, particle scavenging intensity and the oxidation state of seawater. However, their generally low (˜pmol/kg) concentrations in seawater and fractionation potential during chemical treatment makes them difficult to measure. Here we report a technique using an automated preconcentration system, which efficiently separates seawater matrix elements and elutes the preconcentrated sample directly into the spray chamber of an ICP-MS instrument. The commercially available "seaFAST" system (Elemental Scientific Inc.) makes use of a resin with ethylenediaminetriacetic acid and iminodiacetic acid functional groups to preconcentrate REEs and other metals while anions and alkali and alkaline earth cations are washed out. Repeated measurements of seawater from 2000 m water depth in the Southern Ocean allows the external precision (2?) of the technique to be estimated at <23% for all REEs and <15% for most. Comparison of Nd concentrations with isotope dilution measurements for 69 samples demonstrates that the two techniques generally agree within 15%. Accuracy was found to be good for all REEs by using a five point standard addition analysis of one sample and comparing measurements of mine water reference materials diluted with a NaCl matrix with recommended values in the literature. This makes the online preconcentration ICP-MS technique advantageous for the minimal sample preparation required and the relatively small sample volume consumed (7 mL) thus enabling large data sets for the REEs in seawater to be rapidly acquired.

  11. Chemical properties of rare earth elements in typical medical waste incinerator ashes in China.

    PubMed

    Zhao, Lijuan; Zhang, Fu-Shen; Zhang, Jingxin

    2008-10-30

    Medical waste (MW) ashes from different types of MW incinerators were examined to detect the characteristics and environmental impact of rare earth elements (REEs). The results showed that total REE contents in the ash samples ranged from 10.2 to 78.9 mg/kg. REEs in bottom ash were apparently higher than those in fly ash. Average REE contents in the ashes followed the sequence of Ce>La>Nd>Y>Gd>Pr>Sm>Dy>Er>Yb>Ho>Eu>Tb>Lu>Tm. Some of the elements, such as Sm, Dy, Ho, Er, Yb in the ash samples were in normal or nearly normal distribution, but Y, La, Ce, Pr, Nd, Eu, Gd, Tb, Tm, Lu were not normally distributed, indicating some of the ash samples were enriched with these elements. Crust-normalized REE patterns indicated that two types of the MW ashes were obviously enriched with Gd and La. Sequential extraction results showed that REEs in the ash mainly presented as residual fraction, while exchangeable and carbonate fractions were relatively low. DTPA- and EDTA-extraction tests indicated that REEs in the MW ashes were generally in low bioavailability. PMID:18329796

  12. Rare earth elements activate endocytosis in plant cells

    PubMed Central

    Wang, Lihong; Li, Jigang; Zhou, Qing; Yang, Guangmei; Ding, Xiao Lan; Li, Xiaodong; Cai, Chen Xin; Zhang, Zhao; Wei, Hai Yan; Lu, Tian Hong; Deng, Xing Wang; Huang, Xiao Hua

    2014-01-01

    It has long been observed that rare earth elements (REEs) regulate multiple facets of plant growth and development. However, the underlying mechanisms remain largely unclear. Here, using electron microscopic autoradiography, we show the life cycle of a light REE (lanthanum) and a heavy REE (terbium) in horseradish leaf cells. Our data indicate that REEs were first anchored on the plasma membrane in the form of nanoscale particles, and then entered the cells by endocytosis. Consistently, REEs activated endocytosis in plant cells, which may be the cellular basis of REE actions in plants. Moreover, we discovered that a portion of REEs was successively released into the cytoplasm, self-assembled to form nanoscale clusters, and finally deposited in horseradish leaf cells. Taken together, our data reveal the life cycle of REEs and their cellular behaviors in plant cells, which shed light on the cellular mechanisms of REE actions in living organisms. PMID:25114214

  13. Rare Earth elements in individual minerals in Shergottites

    NASA Technical Reports Server (NTRS)

    Wadhwa, Meenakshi; Crozaz, Ghislaine

    1993-01-01

    Shergottites (i.e., Shergotty, Zagami, EETA79001, ALHA77005, and LEW88516) are an important set of achondrites because they comprise the majority of the SNC group of meteorites (nine, in total, known to us), which are likely to be samples of the planet Mars. Study of these meteorites may therefore provide valuable information about petrogenetic processes on a large planetary body other than Earth. Rare earth element (REE) distributions between various mineral phases were found to be useful in geochemically modeling the petrogenesis of various rock types (terrestrial and meteoritic). However, with the exception of a few ion microprobe studies and analyses of mineral separates, there has previously not been any comprehensive effort to characterize and directly compare REE in individual minerals in each of the five known shergottites. Ion microprobe analyses were made on thin sections of each of the shergottites. Minerals analyzed were pyroxenes (pigeonite and augite), maskelynite, and whitlockite. The REE concentrations in each mineral type in each shergottite is given.

  14. Fractional Vaporization of Hot Earth-like Exoplanets. L. Schaefer and B. Fegley, Jr. Planetary Chemistry Laboratory,

    E-print Network

    Fractional Vaporization of Hot Earth-like Exoplanets. L. Schaefer and B. Fegley, Jr. Planetary vaporization of a silicate planet. Fractional vaporiza- tion occurs when vapor is continuously removed from Earth (BSE) at 2200 K, shown in Fig. 1. Results: The initial vapor is composed of Na gas, with O2

  15. Assessing the utility of trace and rare earth elements as biosignatures in microbial iron oxyhydroxides

    NASA Astrophysics Data System (ADS)

    Heim, Christine; Simon, Klaus; Ionescu, Danny; Reimer, Andreas; De Beer, Dirk; Quéric, Nadia-Valérie; Reitner, Joachim; Thiel, Volker

    2015-02-01

    Microbial iron oxyhydroxides are common deposits in natural waters, recent sediments and mine drainage systems and often contain significant accumulations of trace and rare earth elements (TREE). TREE patterns are widely used to characterize minerals and rocks, and to elucidate their evolution and origin. Whether and which characteristic TREE signatures distinguish between a biological and an abiological origin of iron minerals is still not well understood. Long-term flow reactor studies were performed in the Äspö Hard Rock Laboratory to investigate the development of microbial mats dominated by iron-oxidizing bacteria, namely Mariprofundus sp. and Gallionella sp. The experiments investigated the accumulation and fractionation of TREE under controlled conditions and enabled us to assess potential biosignatures evolving within the microbial iron oxyhydroxides. Concentrations of Be, Y, Zn, Zr, Hf, W, Th, Pb, and U in the microbial mats were 1e3- to 1e5-fold higher than in the feeder fluids whereas the rare earth elements and Y (REE+Y) contents were 1e4 and 1e6 fold enriched. Except for a hydrothermally induced Eu anomaly, the normalized REE+Y patterns of the microbial iron oxyhydroxides were very similar to published REE+Y distributions of Archaean Banded Iron Formations. The microbial iron oxyhydroxides from the flow reactors were compared to iron oxyhydroxides that were artificially precipitated from the same feeder fluid. These abiotic and inorganic iron oxyhydroxides show the same REE+Y distribution patterns. Our results indicate that the REE+Y mirror quite exactly the water chemistry, but they do not allow to distinguish microbially mediated from inorganic iron precipitates. All TREE studied showed an overall similar fractionation behavior in biogenic, abiotic and inorganic iron oxyhydroxides. Exceptions are Ni and Tl, which were only accumulated in the microbial iron oxyhydroxides and may point to a potential usage of these elements as microbial biosignatures.

  16. What Fraction of Boron-8 Solar Neutrinos arrive at the Earth as a nu_2 mass eigenstate?

    E-print Network

    Hiroshi Nunokawa; Stephen Parke; Renata Zukanovich Funchal

    2006-01-24

    We calculate the fraction of B^8 solar neutrinos that arrive at the Earth as a nu_2 mass eigenstate as a function of the neutrino energy. Weighting this fraction with the B^8 neutrino energy spectrum and the energy dependence of the cross section for the charged current interaction on deuteron with a threshold on the kinetic energy of the recoil electrons of 5.5 MeV, we find that the integrated weighted fraction of nu_2's to be 91 \\pm 2 % at the 95% CL. This energy weighting procedure corresponds to the charged current response of the Sudbury Neutrino Observatory (SNO). We have used SNO's current best fit values for the solar mass squared difference and the mixing angle, obtained by combining the data from all solar neutrino experiments and the reactor data from KamLAND. The uncertainty on the nu_2 fraction comes primarily from the uncertainty on the solar delta m^2 rather than from the uncertainty on the solar mixing angle or the Standard Solar Model. Similar results for the Super-Kamiokande experiment are also given. We extend this analysis to three neutrinos and discuss how to extract the modulus of the Maki-Nakagawa-Sakata mixing matrix element U_{e2} as well as place a lower bound on the electron number density in the solar B^8 neutrino production region.

  17. Evaluating Changes In the Elemental Composition of Micrometeorites During Entry into the Earth’s Atmosphere

    NASA Astrophysics Data System (ADS)

    Rudraswami, N. G.; Shyam Prasad, M.; Dey, S.; Plane, J. M. C.; Feng, W.; Taylor, S.

    2015-11-01

    We evaluate the heating of extraterrestrial particles entering the atmosphere using the comprehensive chemical ablation model (CABMOD). This model predicts the ablation rates of individual elements in a particle with a defined size, composition, entry velocity, and entry angle with respect to the zenith (ZA). In the present study, bulk chemical analyses of 1133 Antarctica micrometeorites (collected from the south pole water well) are interpreted using CABMOD. The marked spread in Fe/Si values in unmelted, partially melted, and melted micrometeorites is explained by the loss of relatively volatile Fe during atmospheric entry. The combined theoretical modeling and elemental composition of the micrometeorites (Mg/Si ratios) suggest that ?85% of particles have a provenance of carbonaceous chondrites, the remaining ?15% are either ordinary or enstatite chondrites. About 65% of the micrometeorites have undergone <20% ablation, while a further 20% have lost between 20% and 60% of their original mass. This has implications for understanding the micrometeorite flux that reaches the Earth's surface, as well as estimating the pre-atmospheric size of the particles. Our work shows that the unmelted particles that contribute ?50% to the total micrometeorite collection on Earth's surface have a small entry zone: ZA = 60°–90° if the entry velocity is ?11 km s?1, and ZA = 80°–90° for >11–21 km s?1.

  18. The lherzolitic shergottite Grove Mountains 99027: Rare earth element geochemistry

    NASA Astrophysics Data System (ADS)

    Hsu, Weibiao; Guan, Yunbin; Wang, Henian; Leshin, Laurie A.; Wang, Rucheng; Zhang, Wenlan; Chen, Xiaoming; Zhang, Fusheng; Lin, Chengyi

    2004-05-01

    We report here on an ion probe study of rare earth element (REE) geochemistry in the lherzolitic shergottite Grove Mountains (GRV) 99027. This meteorite shows almost identical mineralogy, petrology, and REE geochemistry to those of the lherzolitic shergottites Allan Hills (ALH) A77005, Lewis Cliff (LEW) 88516, and Yamato (Y-) 793605. REE concentrations in olivine, pyroxenes, maskelynite, merrillite, and melt glass are basically comparable to previous data obtained from ALH A77005, LEW 88516, and Y-793605. Olivine is the dominant phase in this meteorite. It is commonly enclosed by large (up to several mm) pigeonite oikocrysts. Non-poikilitic areas consist of larger olivine grains (~mm), pigeonite, augite, and maskelynite. Minor merrillite (up to 150 mm in size) is widespread in non-poikilitic regions, occurring interstitially between olivine and pyroxene grains. It is the main REE carrier in GRV 99027 and has relatively higher REEs (200-1000 Å CI) than that of other lherzolitic shergottites. A REE budget calculation for GRV 99027 yields a whole rock REE pattern very similar to that of other lherzolites. It is characterized by the distinctive light REE depletion and a smooth increase from light REEs to heavy REEs. REE microdistributions in GRV 99027 strongly support the idea that all lherzolitic shergottites formed by identical igneous processes, probably from the same magma chamber on Mars. Despite many similarities in mineralogy, petrography, and trace element geochemistry, subtle differences exist between GRV 99027 and other lherzolitic shergottites. GRV 99027 has relatively uniform mineral compositions (both major elements and REEs), implying that it suffered a higher degree of sub-solidus equilibration than the other three lherzolites. It is notable that GRV 99027 has experienced terrestrial weathering in the Antarctic environment, as its olivine and pyroxenes commonly display a light REE enrichment and a negative Ce anomaly. Caution needs to be taken in future chronological studies.

  19. Isotopic fractionation of the major elements of molten basalt by chemical and thermal diffusion

    E-print Network

    by chemical diffusion between a natural basalt and rhyolite. The thermal isotopic fractionations for isotopes of the same element. The iron isotopic mea- surements of the basalt­rhyolite diffusion couple by chemical diffusion between molten basalt and rhyolite (Richter et al., 2003) and large fractionations

  20. Determination of element affinities by density fractionation of bulk coal samples

    USGS Publications Warehouse

    Querol, X.; Klika, Z.; Weiss, Z.; Finkelman, R.B.; Alastuey, A.; Juan, R.; Lopez-Soler, A.; Plana, F.; Kolker, A.; Chenery, S.R.N.

    2001-01-01

    A review has been made of the various methods of determining major and trace element affinities for different phases, both mineral and organic in coals, citing their various strengths and weaknesses. These include mathematical deconvolution of chemical analyses, direct microanalysis, sequential extraction procedures and density fractionation. A new methodology combining density fractionation with mathematical deconvolution of chemical analyses of whole coals and their density fractions has been evaluated. These coals formed part of the IEA-Coal Research project on the Modes of Occurrence of Trace Elements in Coal. Results were compared to a previously reported sequential extraction methodology and showed good agreement for most elements. For particular elements (Be, Mo, Cu, Se and REEs) in specific coals where disagreement was found, it was concluded that the occurrence of rare trace element bearing phases may account for the discrepancy, and modifications to the general procedure must be made to account for these.

  1. Rare earth elements exploitation, geopolitical implications and raw materials trading

    NASA Astrophysics Data System (ADS)

    Chemin, Marie-Charlotte

    2015-04-01

    Rare earth elements (REE) correspond to seventeen elements of the periodic table. They are used in high technology, cracking, electric cars' magnet, metal alloy for batteries, and also in phone construction or ceramics for electronic card. REEs are an important resource for high technology. This project targets 16 years old students in the subject "personalized aid" and will last six weeks. The purpose of this project is to develop autonomy and research in groups for a transdisciplinary work. This project gathers knowledge in geology, geography and economics. During the first session students analyze the geology applications of the REE. They begin the analysis with learning the composition in different rocks such as basalt and diorite to make the link with crystallization. Then they compare it with adakite to understand the formation of these rocks. In the second session, they study REE exploitation. We can find them as oxides in many deposits. The principal concentrations of rare earth elements are associated with uncommon varieties of igneous rocks, such as carbonatites. They can use Qgis, to localize this high concentration. In the third session, they study the environmental costs of REE exploitation. Indeed, the exploitation produces thorium and carcinogenic toxins: sulphates, ammonia and hydrochloric acid. Processing one ton of rare earths produces 2,000 tons of toxic waste. This session focuses, first, on Baotou's region, and then on an example they are free to choose. In the fourth session, they study the geopolitical issues of REE with a focus on China. In fact this country is the largest producer of REE, and is providing 95% of the overall production. REE in China are at the center of a geopolitical strategy. In fact, China implements a sort of protectionism. Indeed, the export tax on REE is very high so, as a foreign company, it is financially attractive to establish a manufacturing subsidiary in China in order to use REE. As a matter of fact, establishing a company in China can lower the production cost (since the company buys the products used in its production at a lower price). In the fifth session, they study the raw materials trading based on the futures contracts example. A producer, to avoid a rise in prices of raw materials used in his production can use derivative products on the financial market: futures contracts for instance. This product ensures a quantity and quality for a price and a delivery date agreed upon today. Actually, producers can use a method called Fix price hedging in order to fix the price of a specific product. The main idea is to balance out the "physical position" (spot market) and the "paper position" (futures market). Even if the REE are commercialized in form of a non-perishable's oxide, the flow of the stock must be guaranteed and this is why it is important for producers to secure their supply of raw materials. In the last session, students search local companies that use REE in their production process and study their strategy on the market.

  2. Geochemical behavior of rare earth elements and other trace elements in the Amazon River

    NASA Astrophysics Data System (ADS)

    Merschel, Gila; Bau, Michael; Dantas, Elton Luiz

    2014-05-01

    Rivers transport large amounts of dissolved and suspended particulate material from the catchment area to the oceans and are a major source of trace metals to seawater. The Amazon River is the world's largest river and supplies approximately 20% of the oceans' freshwater (Molinier et al., 1997). However, the behavior of trace elements, especially particle-reactive elements such as the rare earth elements (REE), within the river as well as in the estuary is not well constrained and rather little is known about their transport mechanisms. This study aims at understanding the transport properties of particle-reactive elements in the Amazon River and some of its major tributaries, including the Rio Solimões, Rio Negro, Tapajos, Xingu and Jari Rivers. Samples were taken at 12 stations, seven of which were located in the Amazon mainstream, while the other five stations sampled its tributaries. To account for the effects of variable discharge, the samples were collected during periods of high and low discharge. We present data for major and trace elements, including REE, of the dissolved and suspended load of these samples. First results indicate that the shale-normalized REE pattern of the dissolved load (filtered through 0.2 µm membranes) of the Amazon mainstream and the Rio Solimões confirm earlier studies (Elderfield et al., 1990; Gerard et al., 2003) and show an enrichment of the middle REE relative to the light and heavy REE (LaSN/GdSN: 0.25 - 0.32; GdSN/YbSN: 1.54 - 1.78). In contrast to the Amazon mainstream and the Rio Solimões, which are considered to be whitewater rivers, blackwater rivers, such as the Rio Negro, have a flat REE pattern with higher REE concentrations than whitewater rivers. The third water-type found in the Amazon Basin is clearwater, e.g. Rio Tapajos, with REE patterns in between those of the other two types, i.e. LaSN/GdSN: 0.55 - 0.70; GdSN/YbSN: 1.26 - 1.55. A similar behavior can be identified for other major and trace elements. While elements such as Ca, Mg, Sr or U are relatively high in whitewater rivers, their concentrations are generally lower in clearwater rivers and lowest in blackwater rivers. In contrast, elements including Si, Rb and Cs have their highest concentrations in blackwater rivers, intermediate concentrations in clearwater rivers and their lowest concentrations in whitewater river. [1] Elderfield H., Upstill-Goddard R. and Sholkovitz E.R. (1990): The rare earth elements in rivers, estuaries and coastal seas and their significance to the composition of ocean waters. Geochim.Cosmochim.Acta, 54, 971-991 [2] Gerard M., Seyler P., Benedetti M.F., Alves V.P., Boaventura G.R. and Sondag, F. (2003): Rare earth elements in the Amazon basin. Hydrological Processes, 17, 1379-1392 [3] Molinier M., Guyot J.L., Callede J., Guimaraes V., Oliveira E. and Filizola N. (1997): Hydrologie du bassinamazonien. Evironment et développement en Amazonie brésiliènne, Thery H. (ed.), Berlin Publ., Paris; 24-41

  3. Trace elements in ocean ridge basalt glasses - Implications for fractionations during mantle evolution and petrogenesis

    NASA Technical Reports Server (NTRS)

    Hertogen, J.; Janssens, M.-J.; Palme, H.

    1980-01-01

    Seven documented and fresh glassy selvages from ocean floor basalt pillows were analyzed for trace elements including Ag, Au, Bi, Br, Ni, Pd, and Zn using radiochemical activation analysis. Glasses from DSDP leg 24, site 238 in the Indian Ocean have a trace element pattern which reflects secondary processes at a shallow depth. Chemical fractionations in petrogenesis of tholeiitic basalts indicate that (Ir, Os), Au, Pd, Ni, and Re are strongly fractionated in igneous processes; the unfractionated chondritic mantle pattern thus imposes constraints on mantle evolution models. Finally, the limited Rb/Cs fractionation in oceanic tholeiites reflects the low abundance of volatiles and hydrous silicates in normal ocean ridge basalts.

  4. Distribution of 28 elements in size fractions of lunar mare and highlands soils

    NASA Technical Reports Server (NTRS)

    Boynton, W. V.; Wasson, J. T.

    1977-01-01

    Four volatile, six siderophile and 18 generally lithophile elements were determined in six sieve fractions of mare soil 15100 (moderately mature) and seven sieve fractions of highlands soil 66080 (highly mature). Previous work (Boynton et al., 1976) showed that the volatile elements in lunar soils were enriched in the finest size fraction relative to the coarsest factors by up to about 20. The present investigation tests Boynton's interpretation that the distribution pattern of the volatiles indicates the presence of two components: a volume-correlated component having volatile concentrations independent of grain size and a surface-correlated component with concentration increasing with decreasing grain size.

  5. Targeting heavy rare earth elements in carbonatite complexes

    NASA Astrophysics Data System (ADS)

    Broom-Fendley, S.; Wall, F.; Gunn, A. G.; Dowman, E.

    2012-04-01

    The world's main sources of the rare earth elements (REE) are concentrated in carbonatite complexes. These have the advantages of high grade and tonnage, combined with low thorium contents, yet they are generally enriched in light rare earths (LREE). The heavy rare earths (HREE, which include Eu-Lu and Y) are more highly sought after because of their role in new and green technologies. HREE are predominantly extracted from ion-adsorption clays in China. These are small, low grade deposits, which are often illegally mined by artisans. Increased government control, environmental legislation and local demand for REE in China have led to high prices and global concerns about the security of supply of the HREE. Alternative sources of the HREE are poorly documented. We present a review of such targets, including: (1) 'abnormal' carbonatites; (2) areas around LREE-rich complexes such as breccia, fenite and latter stage veins; and (3) weathered carbonatites. At Lofdal, Namibia, carbonatite dykes contain xenotime-(Y) together with LREE minerals. The original chemistry of the carbonatite magma, coupled with late-stage magma and fluid evolution, seem to be controlling factors [1, 2]. The Khibina carbonatite, Kola Peninsula, Russia, is an example of where early LREE carbonatites become increasing HREE-enriched as magmas evolve to carbo-hydrothermal fluids [3]. Around carbonatite complexes in Malawi HREE enrichment can be found in breccia and in fenite. Breccia around Songwe shows areas with high Y/La ratios within the matrix caused by narrow zones of xenotime enrichment. Fenite around Kangankunde and Chilwa Island has higher HREE:LREE ratios than the carbonatite [4]. At weathered complexes, such as at Mount Weld in Western Australia, changes in both HREE concentration and LREE:HREE ratios are observed. In currently unworked sections of the deposit, the HREE mineral churchite (YPO4.H2O) has formed concentrations due to groundwater flow [5]. These areas of enrichment are reviewed in terms of their grade, tonnage, rock type and the potential environmental impacts associated with their exploitation. [1] Wall et al. (2008), Can Mineral, 46, 861. [2] Do Cabo et al. (2011), Minmag, 75 (3), 770. [3] Zaitsev et al. (1998), Minmag, 62 (2), 225. [4] Dowman et al. (2011), abstract, Fermor conference, London. [5] Lottermoser (1990), Lithos, 24, 151

  6. A method for predicting bioavailability of rare earth elements in soils to maize.

    PubMed

    Wang, Wei-Sheng; Shan, Xiao-Quan; Wen, Bei; Zhang, Shu-Zhen

    2004-03-01

    A single-extraction procedure using low-molecular-weight organic acids (LMWOAs) as extractant and the first and second steps of a three-step extraction procedure recommended by the European Community Bureau of Reference (BCR; now European Community Standards, Measurement and Testing Programme, Brussels, Belgium) were performed to extract the light rare earth elements (LREEs) La, Ce, Pr, and Nd from wet rhizosphere soil. The extracted soil solutions were successively filtered through membranes with a pore size of less than 0.45 microm and a molecular weight cutoff of less than 1 kDa, which were termed colloidal and truly dissolved fractions, respectively. Apoplastically and symplastically bound LREEs in maize roots were experimentally distinguished by ultrasound-assisted desorption with 1 mM CaCl2 solution at 0 degrees C in ice-cooled water bath. When the LMWOAs extraction method was used, a good correlation was obtained between LREEs in soil colloidal and truly dissolved fractions and LREEs bound to apoplasm and symplasm of maize root. Both apoplastically and symplastically bound LREEs are the result of bioavailability. However, a poor correlation was obtained between LREEs in fractions water soluble, exchangeable and carbonate bound (B1) and Fe-Mn oxide bound (B2) of the BCR method and LREEs in apoplasm and symplasm and in intact roots. Hence, the LMWOAs extraction method is recommended for measuring the bioavailability of LREEs in soils. PMID:15285371

  7. The geochemistry of rare earth elements in the Amazon River estuary

    SciTech Connect

    Shokovitz, E.R. )

    1993-05-01

    The estuarine geochemistry of rare earth elements (REEs) was studied using samples collected in the Amazon River estuary from the AmasSeds (Amazon Shelf SEDiment Study) cruise of August 1989. Extensive removal of dissolved (0.22 [mu]m filtered) trivalent REEs from river water occurs in the low (0--6) salinity region. Removal by the salt-induced coagulation of river colloids leads to fractionation among the REE(III) series; the order of removal is light REEs > middle REEs > heavy REEs. There also is the enhanced removal of Ce (relative to trivalent La and Nd) in the low salinity (0--6) zone and in the zone of high biological activity. This is the first field observation of strong Ce removal associated with coagulation of river colloids and biological productivity. The argument is made that the decrease in the Ce anomaly across a biological front is caused by biologically mediated oxidation of Ce(III) to Ce(IV). Coagulation of river colloids and biologically mediated oxidation of Ce(III) lead to fractionation of REE(III) and redox modification of Ce. These processes result in the REE composition becoming fractionated relative to the Amazon River water and crust and more evolved toward the REE composition of the oceans. This study implies that reactions in estuaries play significant, yet poorly understood roles in controlling the REE composition and Ce anomaly of the oceans. 46 refs., 9 figs., 2 tabs.

  8. Geochemistry of rare earth elements in a passive treatment system built for acid mine drainage remediation.

    PubMed

    Prudêncio, Maria Isabel; Valente, Teresa; Marques, Rosa; Sequeira Braga, Maria Amália; Pamplona, Jorge

    2015-11-01

    Rare earth elements (REE) were used to assess attenuation processes in a passive system for acid mine drainage treatment (Jales, Portugal). Hydrochemical parameters and REE contents in water, soils and sediments were obtained along the treatment system, after summer and winter. A decrease of REE contents in the water resulting from the interaction with limestone after summer occurs; in the wetlands REE are significantly released by the soil particles to the water. After winter, a higher water dynamics favors the AMD treatment effectiveness and performance since REE contents decrease along the system; La and Ce are preferentially sequestered by ochre sludge but released to the water in the wetlands, influencing the REE pattern of the creek water. Thus, REE fractionation occurs in the passive treatment systems and can be used as tracer to follow up and understand the geochemical processes that promote the remediation of AMD. PMID:26247412

  9. Binary rare earth element-Ni/Co metallic glasses with distinct ?-relaxation behaviors

    NASA Astrophysics Data System (ADS)

    Zhu, Z. G.; Wang, Z.; Wang, W. H.

    2015-10-01

    We report the formation of a series of rare earth element (RE)-Ni/Co binary metallic glasses (MGs) with unusual distinct ?-relaxation peak compared with that of most of the reported MGs which usually exhibit as an excess wing or a shoulder. The ?-relaxation behavior of RE-Ni/Co MGs is sensitive to the composition and the atomic radii of the RE and can be tuned through changing the fraction of RE-Ni (or Co) atomic pairs. The novel RE-Ni/Co MGs with distinct ?-relaxation can serve as model system to investigate the nature of the ?-relaxation as well as its relations with other physical and mechanical properties of MGs.

  10. Fractionation of trace elements in total atmospheric deposition by filtrating-bulk passive sampling.

    PubMed

    Rueda-Holgado, F; Palomo-Marín, M R; Calvo-Blázquez, L; Cereceda-Balic, F; Pinilla-Gil, E

    2014-07-01

    We have developed and validated a new simple and effective methodology for fractionation of soluble and insoluble forms of trace elements in total atmospheric deposition. The proposed methodology is based on the modification of a standard total deposition passive sampler by integrating a quartz fiber filter that retains the insoluble material, allowing the soluble fraction to pass through and flow to a receiving bottle. The quartz filter containing the insoluble fraction and the liquid containing the soluble fraction are then separately assayed by standardized ICP-MS protocols. The proposed atmospheric elemental fractionation sampler (AEFS) was validated by analyzing a Coal Fly Ash reference material with proper recoveries, and tested for field fractionation of a set of 10 key trace elements in total atmospheric deposition at the industrial area of Puchuncaví-Ventanas, Chile. The AEFS was proven useful for pollution assessment and also to identify variability of the soluble and insoluble fractions of the selected elements within the study area, improving the analytical information attainable by standard passive samplers for total deposition without the need of using sophisticated and high cost wet-only/dry only collectors. PMID:24840424

  11. Siderophile element fractionation in meteor crater impact glasses and metallic spherules

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; See, T. H.; Scott, E. R. D.

    1993-01-01

    Meteor Crater, Arizona provides an opportunity to study, in detail, elemental fractionation processes occurring during impacts through the study of target rocks, meteorite projectile and several types of impact products. We have performed EMPA and INAA on target rocks, two types of impact glass and metallic spherules from Meteor Crater. Using literature data for the well studied Canyon Diablo iron we can show that different siderophite element fractionations affected the impact glasses than affected the metallic spherules. The impact glasses primarily lost Au, while the metallic spherules lost Fe relative to other siderophile elements.

  12. Rare earth element components in atmospheric particulates in the Bayan Obo mine region

    SciTech Connect

    Wang, Lingqing Liang, Tao Zhang, Qian; Li, Kexin

    2014-05-01

    The Bayan Obo mine, located in Inner Mongolia, China, is the largest light rare earth body ever found in the world. The research for rare earth elements (REEs) enrichment in atmospheric particulates caused by mining and ore processing is fairly limited so far. In this paper, atmospheric particulates including total suspended particulate (TSP) matter and particles with an equivalent aerodynamic diameter less than 10 ?m (PM{sub 10}) were collected around the Bayan Obo mine region, in August 2012 and March 2013, to analyze the levels and distributions of REEs in particles. The total concentrations of REEs for TSP were 149.8 and 239.6 ng/m{sup 3}, and those for PM{sub 10} were 42.8 and 68.9 ng/m{sup 3}, in August 2012 and March 2013, respectively. Enrichment factor was calculated for all 14 REEs in the TSP and PM{sub 10} and the results indicated that REEs enrichment in atmosphere particulates was caused by anthropogenic sources and influenced by the strong wind in springtime. The spatial distribution of REEs in TSP showed a strong gradient concentration in the prevailing wind direction. REE chondrite normalized patterns of TSP and PM{sub 10} were similar and the normalized curves inclined to the right side, showing the conspicuous fractionation between the light REEs and heavy REE, which supported by the chondrite normalized concentration ratios calculated for selected elements (La{sub N}/Yb{sub N}, La{sub N}/Sm{sub N}, Gd{sub N}/Yb{sub N}). - Highlights: • TSP and PM{sub 10} samples were collected to analyze the levels and distributions of REE. • Enrichment factors indicated that REE enrichment was caused by anthropogenic sources. • The distribution of REEs showed a strong gradient in the prevailing wind direction. • Obvious fractionation between LREEs and HREEs is observed in atmospheric particulates.

  13. Project EARTH-15-WH1: Trace element cycling in the ocean's bottom boundary layer

    E-print Network

    Henderson, Gideon

    Project EARTH-15-WH1: Trace element cycling in the ocean's bottom boundary layer Supervisors: Dr Will Homoky, Prof. Gideon Henderson (Earth Sciences) The entire ocean floor is overlain by a bottom boundary layer of seawater that hosts dynamic properties[1] , able to moderate the release and uptake of elements

  14. A study of solute transport mechanisms using rare earth element tracers and artificial rainstorms on snow

    E-print Network

    Kirchner, James W.

    and Susan Taylor1,5 Abstract. Rare earth element (REE) tracers and three artificial rain-on-snow stormsA study of solute transport mechanisms using rare earth element tracers and artificial rainstorms on snow Xiahong Feng,1 James W. Kirchner,2 Carl E. Renshaw,1 Randall S. Osterhuber,3 Bjo¨rn Klaue,4

  15. Stable isotope and Rare Earth Element evidence for recent ironstone pods within the Archean Barberton

    E-print Network

    Hren, Michael

    Stable isotope and Rare Earth Element evidence for recent ironstone pods within the Archean greenstone belt. We examined oxygen and hydrogen isotopes and Rare Earth Element (REE) concentrations of these Archean chemical sediments contain a high percentage of oxidized iron, frequently found in discrete

  16. Effects of spraying rare earths on contents of rare Earth elements and effective components in tea.

    PubMed

    Wang, Dongfeng; Wang, Changhong; Ye, Sheng; Qi, Hongtao; Zhao, Guiwen

    2003-11-01

    Rare earth (RE) fertilizer is widely applied in China to increase the yield and the quality of crops including tea. However, the effects of spraying RE fertilizer on the contents of rare earth elements (REE) and effective components in tea are unknown. The results from basin and field experiments show that the values of the REE concentrations in new shoots of tea plants and the concentration of REE in the soil (REE/REEs) either from control basins or from treatment basins were smaller than those in other parts of tea plant and similar between control and treatment. The longer the interval between spraying RE fertilizer and picking the shoots of tea plants, the less the effects from spraying. About 80% summation operator REE (the sum of the concentrations of 15 REE) in tea, whether it came from spraying or not, was insoluble in the infusion. About 10% the soluble REE of summation operator REE in tea infusion was bound to polysaccharide, and the amount of REE bound polysaccharide decreased over time. At least a 25 day safety interval is needed between spraying and picking if the microelement fertilizer is used, in order to enhance tea output and to ensure tea safety. PMID:14582968

  17. Volatile elements in chondrites - Metamorphism or nebular fractionation

    NASA Technical Reports Server (NTRS)

    Takahashi, H.; Gros, J.; Higuchi, H.; Morgan, J. W.; Anders, E.

    1978-01-01

    Three of the most highly metamorphosed meteorites of their respective classes, Shaw (LL7), Karoonda (C5), and Coolidge (C4), were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Se, Te, Tl, U, and Zn. Comparison with data by Lipschutz and coworkers (1977) on artificially heated primitive meteorites shows that the natural metamorphism of meteorites cannot have taken place in a system open to volatiles. Shaw, metamorphosed at 1300 C for more than 1 million yr, is less depleted in In, Bi, Ag, Te, Zn, and Tl than Krymka heated at 1000 C for 1 week. Karoonda, metamorphosed at 600 C for many millennia, is less depleted in Bi and Tl than Allende heated at 600 C for 1 week. Data on primordial noble gases also show that the volatile-element patterns of ordinary and carbonaceous chondrites were established by nebular condensation and changed little, if at all, during metamorphism. For enstatite chondrites, the evidence is still incomplete but seems to favor a nebular origin of the volatile pattern.

  18. Skeleton versus fine earth: what information is stored in the mobile extracellular soil DNA fraction?

    NASA Astrophysics Data System (ADS)

    Ascher, Judith; Ceccherini, Maria Teresa; Agnelli, Alberto; Corti, Guiseppe; Pietramellara, Giacomo

    2010-05-01

    The soil genome consists of an intracellular and an extracellular fraction. Recently, soil extracellular DNA (eDNA) has been shown to be quantitatively relevant, with a high survival capacity and mobility, playing a crucial role in the gene transfer by transformation, in the formation of bacterial biofilm and as a source of nutrients for soil microorganisms. The eDNA fraction can be discriminated and classified by its interaction with clay minerals, humic acids and Al/Fe oxihydroxides, resulting in differently mobile components. The eDNA extractable in water, classified as DNA free in the extracellular soil environment or adsorbed on soil colloids (eDNAfree/adsorbed), is hypothesized to be the most mobile DNA in soil. Challenging to assess the information stored in this DNA fraction, eDNAfree/adsorbed was recovered from fine earth (< 4 mm) and highly altered rock fragments or skeleton (4-10 mm) of six consecutive horizons (A1-BCb2) of a forest soil profile by washing the two soil fractions with H2O. Quantitative analysis have been conducted in terms of DNA yields (fluorimeter and spectrophotometer), molecular weight and fragment length distribution (gel electrophoresis), and qualitative analysis in terms of the composition and distribution of fungal and bacterial communities (Denaturing Gradient Gel Electrophoresis- fingerprinting). The mobile soil eDNA, extracted from each horizon, was characterised by low molecular weight (< 2 kb) and amounts ranging from 3.96 (±0.179) to 0.17 (±0.023) µg g-1 for the fine earth and from 1.42 (±0.111) to 0.11 (±0.007) µg g-1 for the skeleton. Genetic fingerprinting of eDNA recovered from fine earth and skeleton revealed characteristic fungal and bacterial communities of each horizon, but also similarities among the microbial communities of both soil fractions and horizons. This could be interpreted also as a result of the movement of eDNA along the soil profile and from fine earth to skeleton. The molecular characterization provided information about the autochthonous microflora inhabiting skeleton and fine earth as well as information about the fate of soil DNA in terms of presence, persistence and movement of eDNA and the stored genetic information.

  19. Distribution of rare earth elements in an alluvial aquifer affected by acid mine drainage: the Guadiamar aquifer (SW Spain).

    PubMed

    Olías, M; Cerón, J C; Fernández, I; De la Rosa, J

    2005-05-01

    This work analyses the spatial distribution, the origin, and the shale-normalised fractionation patterns of the rare earth elements (REE) in the alluvial aquifer of the Guadiamar River (south-western Spain). This river received notoriety in April 1998 for a spill that spread a great amount of slurry (mainly pyrites) and acid waters in a narrow strip along the river course. Groundwaters and surface waters were sampled to analyse, among other elements, the REEs. Their spatial distribution shows a peak close to the mining region, in an area with low values of pH and high concentrations of sulphates and other metals such as Zn, Cu, Co, Ni, Pb, and Cd. The patterns of shale-normalised fractionation at the most-contaminated points show an enrichment in the middle rare earth elements (MREE) with respect to the light (LREE) and heavy (HREE) ones, typical of acid waters. The Ce-anomaly becomes more negative as pH increases, due to the preferential fractionation of Ce in oxyhydroxides of Fe. PMID:15701392

  20. Carbonatite and alkaline intrusion-related rare earth element deposits–A deposit model

    USGS Publications Warehouse

    Verplanck, Philip L.; Van Gosen, Bradley S.

    2011-01-01

    The rare earth elements are not as rare in nature as their name implies, but economic deposits with these elements are not common and few deposits have been large producers. In the past 25 years, demand for rare earth elements has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare earth elements come from only a few sources. China produces more than 95 percent of the world's supply of rare earth elements. Because of China's decision to restrict exports of these elements, the price of rare earth elements has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare earth elements deposits, and identifying and quantifying our nation's rare earth elements resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. The general mineral deposit model summarized here is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. Carbonatite and alkaline intrusion-related REE deposits are discussed together because of their spatial association, common enrichment in incompatible elements, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare earth elements, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.

  1. Recovery of rare earth elements from the sulfothermophilic red alga Galdieria sulphuraria using aqueous acid.

    PubMed

    Minoda, Ayumi; Sawada, Hitomi; Suzuki, Sonoe; Miyashita, Shin-ichi; Inagaki, Kazumi; Yamamoto, Takaiku; Tsuzuki, Mikio

    2015-02-01

    The demand for rare earth elements has increased dramatically in recent years because of their numerous industrial applications, and considerable research efforts have consequently been directed toward recycling these materials. The accumulation of metals in microorganisms is a low-cost and environmentally friendly method for the recovery of metals present in the environment at low levels. Numerous metals, including rare earth elements, can be readily dissolved in aqueous acid, but the efficiency of metal biosorption is usually decreased under the acidic conditions. In this report, we have investigated the use of the sulfothermophilic red alga Galdieria sulphuraria for the recovery of metals, with particular emphasis on the recovery of rare earth metals. Of the five different growth conditions investigated where G. sulphuraria could undergo an adaptation process, Nd(III), Dy(III), and Cu(II) were efficiently recovered from a solution containing a mixture of different metals under semi-anaerobic heterotrophic condition at a pH of 2.5. G. sulphuraria also recovered Nd(III), Dy(III), La(III), and Cu(II) with greater than 90% efficiency at a concentration of 0.5 ppm. The efficiency remained unchanged at pH values in the range of 1.5-2.5. Furthermore, at pH values in the range of 1.0-1.5, the lanthanoid ions were collected much more efficiently into the cell fractions than Cu(II) and therefore successfully separated from the Cu(II) dissolved in the aqueous acid. Microscope observation of the cells using alizarin red suggested that the metals were accumulating inside of the cells. Experiments using dead cells suggested that this phenomenon was a biological process involving specific activities within the cells. PMID:25283836

  2. Core-Mantle Partitioning of Volatile Siderophile Elements and the Origin of Volatile Elements in the Earth

    NASA Technical Reports Server (NTRS)

    Nickodem, K.; Righter, K.; Danielson, L.; Pando, K.; Lee, C.

    2012-01-01

    There are currently several hypotheses on the origin of volatile siderophile elements in the Earth. One hypothesis is that they were added during Earth s accretion and core formation and mobilized into the metallic core [1], others claim multiple stage origin [2], while some hypothesize that volatiles were added after the core already formed [3]. Several volatile siderophile elements are depleted in Earth s mantle relative to the chondrites, something which continues to puzzle many scientists. This depletion is likely due to a combination of volatility and core formation. The Earth s core is composed of Fe and some lighter constituents, although the abundances of these lighter elements are unknown [4]. Si is one of these potential light elements [5] although few studies have analyzed the effect of Si on metal-silicate partitioning, in particular the volatile elements. As, In, Ge, and Sb are trace volatile siderophile elements which are depleted in the mantle but have yet to be extensively studied. The metal-silicate partition coefficients of these elements will be measured to determine the effect of Si. Partition coefficients depend on temperature, pressure, oxygen fugacity, and metal and silicate composition and can constrain the concentrations of volatile, siderophile elements found in the mantle. Reported here are the results from 13 experiments examining the partitioning of As, In, Ge, and Sb between metallic and silicate liquid. These experiments will examine the effect of temperature, and metal-composition (i.e., Si content) on these elements in or-der to gain a greater understanding of the core-mantle separation which occurred during the Earth s early stages. The data can then be applied to the origin of volatile elements in the Earth.

  3. Recovery and Separation of Rare Earth Elements Using Salmon Milt

    PubMed Central

    Takahashi, Yoshio; Kondo, Kazuhiro; Miyaji, Asami; Watanabe, Yusuke; Fan, Qiaohui; Honma, Tetsuo; Tanaka, Kazuya

    2014-01-01

    Recycling rare earth elements (REEs) used in advanced materials such as Nd magnets is important for the efficient use of REE resources when the supply of several REEs is limited. In this work, the feasibility of using salmon milt for REE recovery and separation was examined, along with the identification of the binding site of REEs in salmon milt. Results showed that (i) salmon milt has a sufficiently high affinity to adsorb REEs and (ii) the adsorption capacity of the milt is 1.04 mEq/g, which is comparable with that of commercial cation exchange resin. Heavier REEs have higher affinity for milt. A comparison of stability constants and adsorption patterns of REEs discussed in the literature suggests that the phosphate is responsible for the adsorption of REE in milt. The results were supported by dysprosium (Dy) and lutetium (Lu) LIII-edge extended x-ray absorption fine structure (EXAFS) spectroscopy. The REE-P shell was identified for the second neighboring atom, which shows the importance of the phosphate site as REE binding sites. The comparison of REE adsorption pattern and EXAFS results between the milt system and other adsorbent systems (cellulose phosphate, Ln-resin, bacteria, and DNA-filter hybrid) revealed that the coordination number of phosphate is correlated with the slope of the REE pattern. The separation column loaded with milt was tested to separate REE for the practical use of salmon milt for the recovery and separation of REE. However, water did not flow through the column possibly because of the hydrophobicity of the milt. Thus, sequential adsorption–desorption approach using a batch-type method was applied for the separation of REE. As an example of the practical applications of REE separation, Nd and Fe(III) were successfully separated from a synthetic solution of Nd magnet waste by a batch-type method using salmon milt. PMID:25490035

  4. Composition of the earth's upper mantle-I. Siderophile trace elements in ultramafic nodules

    USGS Publications Warehouse

    Morgan, J.W.; Wandless, G.A.; Petrie, R.K.; Irving, A.J.

    1981-01-01

    Seven siderophile elements (Au, Ge, Ir, Ni, Pd, Os, Re) were determined by radiochemical neutron activation analysis in 19 ultramafic rocks, which are spinel lherzollites-xenoliths from North and Central America, Hawaii and Australia, and garnet Iherzolitexenoliths from Lesotho. Abundances of the platinum metals are very uniform in spinel lherzolites averaging 3.4 ?? 1.2 ppb Os, 3.7 ?? 1.1 ppb Ir, and 4.6 ?? 2.0 ppb Pd. Sheared garnet lherzolite PHN 1611 has similar abundances of these elements, but in 4 granulated garnet lherzolites, abundances are more variable. In all samples, the Pt metals retain cosmic ( Cl-chondrite) ratios. Abundances of Au and Re vary more than those of Pt metals, but the Au/Re ratio remains close to the cosmic value. The fact that higher values of Au and Re approach cosmic proportions with respect to the Pt metals, suggests that Au and Re have been depleted in some ultramafic rocks from an initially chondrite-like pattern equivalent to about 0.01 of Cl chondrite abundances. The relative enrichment of Au and Re in crustal rocks is apparently the result of crust-mantle fractionation and does not require a special circumstance of core-mantle partitioning. Abundances of moderately volatile elements Ni, Co and Ge are very uniform in all rocks, and are much higher than those of the highly siderophile elements Au, Ir, Pd, Os and Re. When normalized to Cl chondrites, abundances of Ni and Co are nearly identical, averaging 0.20 ?? 0.02 and 0.22 ?? 0.02, respectively; but Ge is only 0.027 ?? 0.004. The low abundance of Ge relative to Ni and Co is apparently a reflection of the general depletion of volatile elements in the Earth. The moderately siderophile elements cannot be derived from the same source as the highly siderophile elements because of the marked difference in Cl chondrite-normalized abundances and patterns. We suggest that most of the Ni, Co and Ge were enriched in the silicate by the partial oxidation of pre-existing volatile-poor Fe-Ni, whereas the corresponding highly siderophile elements remained sequestered by the surviving metal. The highly siderophile elements may have been introduced by a population of ~103 large (~1022 g) planetisimals, similar to those forming the lunar mare basins. ?? 1981.

  5. Size fractionation of trace elements in the surface water and groundwater of the Ganjiang River and Xiushui River basins, China

    NASA Astrophysics Data System (ADS)

    Soldatova, E. A.; Guseva, N. V.; Sun, Z.; Mazurova, I. S.

    2015-11-01

    The research of trace element behaviour and size fractionation is significant to understand the processes in the water-rock system. Moreover, the aqueous speciation of trace elements is strongly related to their distribution and toxicity. In this research, trace elements behaviour and their size fractionation are investigated in the natural water (the surface water and shallow groundwater) of the Ganjiang River and Xiushui River basins. Trace element concentrations were measured by ICP-MS. The authors estimated the size fractionation of the trace elements between suspended forms (>0.45?m) and dissolved fractions, which included truly dissolved (1 kDa) and colloidal particles (0.45?m-1 kDa)), after filtration through a 0.45 ?m acetate cellulose membrane filter. The distinct features of the trace element size fractionation were identified. The size fractionation of the trace elements under different conditions (in the surface water and shallow groundwater) was studied.

  6. A new mixed element method for a class of time-fractional partial differential equations.

    PubMed

    Liu, Yang; Li, Hong; Gao, Wei; He, Siriguleng; Fang, Zhichao

    2014-01-01

    A kind of new mixed element method for time-fractional partial differential equations is studied. The Caputo-fractional derivative of time direction is approximated by two-step difference method and the spatial direction is discretized by a new mixed element method, whose gradient belongs to the simple (L (2)(?)(2)) space replacing the complex H(div; ?) space. Some a priori error estimates in L (2)-norm for the scalar unknown u and in (L (2))(2)-norm for its gradient ?. Moreover, we also discuss a priori error estimates in H (1)-norm for the scalar unknown u. PMID:24737957

  7. RARE EARTH ELEMENTS: A REVIEW OF PRODUCTION, PROCESSING, RECYCLING, AND ASSOCIATED ENVIRONMENTAL ISSUES

    EPA Science Inventory

    Rare earth elements (REEs) are a group of 15 chemical elements in the periodic table, specifically the lanthanides. Two other elements, scandium and yttrium, have a similar physiochemistry to the lanthanides, are commonly found in the same mineral assemblages, and are often refe...

  8. Volatility Fractionation of REE and Other Trace Elements During Vacuum Evaporation

    NASA Astrophysics Data System (ADS)

    Davis, A. M.; Hashimoto, A.

    1995-09-01

    Volatility-fractionated REE patterns were first recognized in calcium-, aluminum-rich inclusions (CAIs) in meteorites over 20 years ago [1]. Such REE patterns can be modeled quite well by equilibrium thermodynamic calculations [2,3,4], but kinetic effects on fractionation of trace elements between gas and solids or liquids have remained less well-known. We have previously reported on experiments in which melts of initial REE-doped chondritic composition [5] and perovskite composition [6] were evaporated in vacuo. In both series of experiments, residues were formed that had large negative Ce anomalies and small negative Pr and Eu anomalies, but no other significant REE fractionations were observed. In an effort to produce more extensive fractionation of REE and other refractory elements, we made a new, more refractory, starting material (stoichiometric CaTiO3 doped with a number of refractory trace elements in chondritic proportions to a total "trace" element level of 5 wt%) and evaporated it under vacuum at a higher temperature (2150 degrees C) than the earlier experiments (1800-2000 degrees C). The results are shown in Fig. 1. Despite the high temperature, the two most extreme evaporation residues reached the solidus during evaporation; the other residues with lower degrees of evaporation remained liquid until cooled at the end of the experiment. The most extreme residue consists largely of mixed Sc, Y and Zr oxides; most of the Ti and nearly all of the Ca have evaporated. In this residue, there are large depletions in Sr, Nb, Ba, Ce and Eu and smaller depletions of La, Pr, Nd, Sm and Yb compared to Sc, Zr and most heavy REE. There is, however, little fractionation of the heavy REE from one another. The chemical composition and even the physical state of the residues change with degree of evaporation, undoubtedly affecting evaporation rates of trace elements. For example, even though the experiments are all carried out at a single temperature and both Ce and Eu are quite depleted in the most extreme residue, Ce evaporates early and Eu evaporates late (Fig. 1). Ultrarefractory inclusions show substantial fractionations among the heavy REE that have been attributed to volatility fractionation [7]. Kinetically controlled evaporation produces large isotopic mass fractionation effects in Ca and Ti [6], whereas there is minimal isotopic fractionation between gas and condensed phases at high temperatures. The lack of large isotopic fractionation effects in ultrarefractory inclusions [7] suggests that these objects did not form by kinetically controlled evaporation. The residues we have produced have bulk chemical compositions consistent with ultrarefractory inclusions, as they are composed of mixed Sc, Zr and Y oxides, but they do not have as much heavy to light REE fractionation nor do they show the substantial fractionation among the heavy REE that is characteristic of ultrarefractory inclusions. This difference supports the idea that the volatility fractionations of trace elements observed CAIs are thermodynamically rather than kinetically controlled. References: [1] Tanaka T. and Masuda A. (1973) Icarus, 19, 523-530. [2] Boynton W. V. (1975) GCA, 39, 569-584. [3] Davis A. M. and Grossman L. (1979) GCA, 43, 1611-1632. [4] MacPherson G. J. and Davis A. M. (1994) GCA, 58, 5599-5625. [5] Wang J. et al. (1993) Meteoritics, 28, 454-455. [6] Davis A. M. et al. (1995) LPS XXVI, 317-318. [7] Davis A. M. (1991) Meteoritics, 26, 330. Fig. 1. Elemental enrichment factors in residues of initial stoichiometric CaTiO3 composition doped with 5% refractory trace elements in chondritic relative proportions, plotted in order of atomic number.

  9. Selected Publications 1. Introduction to Radon transforms (with elements of fractional calculus and

    E-print Network

    Rubin, Boris

    Selected Publications Books: 1. Introduction to Radon transforms (with elements of fractional and Applied Mathematics, 82. Longman, Harlow, 1996. xiv+409 pp. ISBN: 0-582- 25341-1. 3. Radon transforms-0-8218-4327-7 42-06. Articles: - Null spaces of Radon transforms (joint with R. Estrada), arXiv:1504.03766. - New

  10. Rare-earth elements in the Permian Phosphoria Formation: Paleo proxies of ocean geochemistry

    USGS Publications Warehouse

    Piper, D.Z.; Perkins, R.B.; Rowe, H.D.

    2007-01-01

    The geochemistry of deposition of the Meade Peak Member of the Phosphoria Formation (MPM) in southeast Idaho, USA, a world-class sedimentary phosphate deposit of Permian age that extends over 300,000 km2, is ascertained from its rare earth element (REE) composition. Ratios of REE:Al2O3 suggest two sources-seawater and terrigenous debris. The seawater-derived marine fraction identifies bottom water in the Phosphoria Sea as O2-depleted, denitrifying (suboxic) most of the time, and seldom sulfate-reducing (anoxic). This interpretation is supported by earlier research that showed progressively greater ratios in the marine sediment fraction of Cr:Ni>V:Ni???Mo:Ni, relative to their ratios in seawater; for which marine Cr, V, and Mo can have a dominantly O2-depleted bottom-water source and Ni a photic-zone, largely algal, source. The water chemistry was maintained by a balance between bacterial oxidation of organic matter settling through the water column, determined largely by primary productivity in the photic zone, and the flux of oxidants into the bottom water via advection of seawater from the open ocean. Samples strongly enriched in carbonate fluorapatite, the dominant REE host mineral, have variable Er/Sm, Tm/Sm, and Yb/Sm ratios. Their distribution may represent greater advection of seawater between the Phosphoria Sea and open ocean during deposition of two ore zones than a center waste and greater upwelling of nutrient-enriched water into the photic zone. However, the mean rate of deposition of marine Ni, a trace nutrient of algae, and PO43-, a limiting nutrient, indicate that primary productivity was probably high throughout the depositional history. An alternative interpretation of the variable enrichments of Er, Tm, and Yb, relative to Sm, is that they may reflect temporally variable carbonate alkalinity of open-ocean seawater in Permian time. A more strongly negative Ce anomaly for all phosphatic units than the Ce anomaly of modern pelletal phosphate is further indicative of an elevated O2 concentration in the Permo-Carboniferous open ocean, as proposed by others, in contrast to the depletion of O2 in the bottom water of the Phosphoria Sea itself. The oceanographic conditions under which the deposit accumulated were likely similar to conditions under which many sedimentary phosphate deposits have accumulated and to conditions under which many black shales that are commonly phosphate poor have accumulated. A shortcoming of several earlier studies of these deposits has resulted from a failure to examine the marine fraction of elements separate from the terrigenous fraction. ?? 2007 Elsevier Ltd. All rights reserved.

  11. Technical Information Resource on Rare Earth Elements Now Available to Public and Private Sector Stakeholders

    EPA Science Inventory

    A new EPA technical information resource, “Rare Earth Elements: A Review of Production, Processing, Recycling, and Associated Environmental Issues” has been produced as an introductory resource for those interested in learning more about REE mining and alternatives to meet demand...

  12. Rare Earth Element Partition Coefficients from Enstatite/Melt Synthesis Experiments

    NASA Technical Reports Server (NTRS)

    Schwandt, Craig S.; McKay, Gordon A.

    1997-01-01

    Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare earth element concentrations were measured in both the basaltic glass and the enstatite. Rare earth element concentrations in the glass were determined by electron microprobe analysis with uncertainties less than two percent relative. Rare earth element concentrations in enstatite were determined by secondary ion mass spectrometry with uncertainties less than five percent relative. The resulting rare earth element partition signature for enstatite is similar to previous calculated and composite low-Ca pigeonite signatures, but is better defined and differs in several details. The partition coefficients are consistent with crystal structural constraints.

  13. The leaching behaviour and geochemical fractionation of trace elements in hydraulically disposed weathered coal fly ash.

    PubMed

    Nyale, Sammy M; Eze, Chuks P; Akinyeye, Richard O; Gitari, Wilson M; Akinyemi, Segun A; Fatoba, Olanrewaju O; Petrik, Leslie F

    2014-01-01

    A five-step sequential extraction (SE) procedure was used to investigate the leaching behaviour and geochemical partitioning of the trace elements As, Zn, Pb, Ni, Mo, Cr and Cu in a 20-year-old fly ash (FA) dump. The weathered FA, which was hydraulically co-disposed with salt laden brine in slurry form (FA: brine ratio of 1:5), was analyzed and compared with fresh FA. The weathered FA samples were collected from three cores, drilled at a coal-fired power station in the Republic of South Africa while the fresh FA sample was collected from the hoppers in the ash collection system at the power station. The FA samples were sequentially leached using: ultrapure water; ammonium acetate buffer solution (pH 7); ammonium acetate buffer solution (pH 5); hydroxylamine hydrochloride in nitric acid (pH 2) and finally the residues were digested using a combination of HClO4: HF: HNO3 acids. Digestion of as received (unleached) FA samples was also done using a combination of HClO4: HF: HNO3 acids in order to determine the total metal content. The trace element analysis was done using ICP-OES (Varian 710-ES). The SE procedure revealed that the trace elements present in the fresh FA and the weathered FA samples obtained from the three cores could leach upon exposure to different environmental conditions. The trace elements showed continuous partitioning between five geochemical phases i.e., water soluble fraction, exchangeable fraction, carbonate fraction, Fe and Mn fraction and residual fraction. Although the highest concentration of the trace elements (ranging 65.51%-86.34%) was contained in the residual fraction, a considerable amount of each trace element (ranging 4.42%-27.43%) was released from the labile phases (water soluble, exchangeable and carbonate fractions), indicating that the trace species readily leach from the dumped FA under environmental conditions thus pose a danger to the receiving environment and to groundwater. PMID:24171424

  14. Lack of chemical fractionation in major and minor elements during agglutinate formation. [in lunar soil

    NASA Technical Reports Server (NTRS)

    Hu, H.-N.; Taylor, L. A.

    1977-01-01

    Rhodes et al. (1975, 1976) and Adams et al. (1975) have reported that the agglutinate fraction of the soils on the lunar surface displays a marked enrichment in Fe, Mg, Ti, K, and La, and a depletion in Ca, Na, Al, and Eu, relative to the bulk soils. The reported investigation is concerned with a testing of the theory of chemical fractionation involving magnetic separation which was developed in connection with these findings. Soils 64421 and 71501 were sieved and the magnetic fractions separated according to the method developed by Adams and McCord (1973). Analyses of agglutinitic glass did not indicate any appreciable chemical fractionation for the major and minor elements accompanying the agglutination process. It was found that most, if not all fractionations reported can be accounted for completely by the magnetic nonagglutinate impurities in the agglutinate fraction. It is, therefore, concluded that there appears to be no reason to make use of any chemical fractionation theory, whose validity remains to be demonstrated.

  15. Rare earth and high field strength element partitioning between iron-rich clinopyroxenes and felsic liquids

    NASA Astrophysics Data System (ADS)

    Olin, P. H.; Wolff, J. A.

    2010-11-01

    Rare earth elements are commonly assumed to substitute only for Ca in clinopyroxene because of the similarity of ionic radii for REE3+ and Ca2+ in eightfold coordination. The assumption is valid for Mg-rich clinopyroxenes for which observed mineral/melt partition coefficients are readily predicted by the lattice strain model for substitution onto a single site (e.g., Wood and Blundy 1997). We show that natural Fe-rich pyroxenes in both silica-undersaturated and silica-oversaturated magmatic systems deviate from this behavior. Salites (Mg# 48-59) in phonolites from Tenerife, ferrohedenbergites (Mg# 14.2-16.2) from the rhyolitic Bandelier Tuff, and ferroaugites (Mg# 9.6-32) from the rhyolitic Rattlesnake Tuff have higher heavy REE contents than predicted by single-site substitution. The ionic radius of Fe2+ in sixfold coordination is substantially greater than that of Mg2+; hence, we propose that, in Fe-rich clinopyroxenes, heavy REE are significantly partitioned between eightfold Ca sites and sixfold Fe and Mg sites such that Yb and Lu exist dominantly in sixfold coordination. We also outline a REE-based method of identifying pyroxene/melt pairs in systems with multiple liquid and crystal populations, based upon the assumption that LREE and MREE reside exclusively in eightfold coordination in pyroxene. Contrary to expectations, interpolation of mineral/melt partition coefficient data for heavy REE does not predict the behavior of Y. We speculate that mass fractionation effects play a role in mineral/melt lithophile trace element partitioning that is detectable among pairs of isovalent elements with near-identical radii, such as Y and Ho, Zr and Hf, and Nb and Ta.

  16. Rare earth element abundances in rocks and minerals from the Fiskenaesset Complex, West Greenland. [comparison with lunar anorthosites

    NASA Technical Reports Server (NTRS)

    Henderson, P.; Fishlock, S. J.; Laul, J. C.; Cooper, T. D.; Conard, R. L.; Boynton, W. V.; Schmitt, R. A.

    1976-01-01

    The paper reports activation-analysis determinations of rare-earth-element (REE) and other trace-element concentrations in selected rocks, plagioclase, and mafic separates from the Fiskenaesset Complex. The REE abundances are found to be very low and atypical in comparison with other terrestrial anorthosites. The plagioclases are shown to be characterized by a deficiency in heavy RE elements relative to light ones and a positive Eu anomaly, while the mafic separates are enriched in heavy rare earths and have no Eu anomaly, except in one sample. It is found that the bulk and trace-element abundances of the plagioclases are similar to those observed in some lunar anorthosites, but the degree of Eu anomaly is less in the plagioclases. The data are taken as confirmation of the idea that fractionation processes were involved in the origin of the Complex, and it is concluded that the Complex may have been produced from a magma generated by partial melting of a garnet-bearing source.

  17. Fractional Snowcover Estimates from Earth Observing System (EOS) Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS)

    NASA Technical Reports Server (NTRS)

    Salomonson, Vincent V.

    2002-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Earth Observing System (EOS) Terra and Aqua missions has shown considerable capability for mapping snowcover. The typical approach that has used, along with other criteria, the Normalized Snow Difference Index (NDSI) that takes the difference between 500 meter observations at 1.64 micrometers (MODIS band 6) and 0.555 micrometers (MODIS band 4) over the sum of these observations to determine whether MODIS pixels are snowcovered or not in mapping the extent of snowcover. For many hydrological and climate studies using remote sensing of snowcover, it is desirable to assess if the MODIS snowcover observations could not be enhanced by providing the fraction of snowcover in each MODIS observation (pixel). Pursuant to this objective studies have been conducted to assess whether there is sufficient "signal%o in the NDSI parameter to provide useful estimates of fractional snowcover in each MODIS 500 meter pixel. To accomplish this objective high spatial resolution (30 meter) Landsat snowcover observations were used and co-registered with MODIS 500 meter pixels. The NDSI approach was used to assess whether a Landsat pixel was or was not snowcovered. Then the number of snowcovered Landsat pixels within a MODIS pixel was used to determine the fraction of snowcover within each MODIS pixel. The e results were then used to develop statistical relationships between the NDSI value for each 500 meter MODIS pixel and the fraction of snowcover in the MODIS pixel. Such studies were conducted for three widely different areas covered by Landsat scenes in Alaska, Russia, and the Quebec Province in Canada. The statistical relationships indicate that a 10 percent accuracy can be attained. The variability in the statistical relationship for the three areas was found to be remarkably similar (-0.02 for mean error and less than 0.01 for mean absolute error and standard deviation). Independent tests of the relationships were accomplished by taking the relationship of fractional snow-cover to NDSI from one area (e.g., Alaska) and testing it on the other two areas (e.g. Russia and Quebec). Again the results showed that fractional snow-cover can be estimated to 10 percent. The results have been shown to have advantages over other published fractional snowcover algorithms applied to MODIS data. Most recently the fractional snow-cover algorithm has been applied using 500-meter observations over the state of Colorado for a period spanning 25 days. The results exhibit good behavior in mapping the spatial and temporal variability in snowcover over that 25-day period. Overall these studies indicate that robust estimates of fractional snow-cover can be attained using the NDSI parameter over areas extending in size from watersheds relatively large compared to MODIS pixels to global land cover. Other refinements to this approach as well as different approaches are being examined for mapping fractional snow-cover using MODIS observations.

  18. Experimental investigations of trace element fractionation in iron meteorites. III - Elemental partitioning in the system Fe-Ni-S-P

    NASA Technical Reports Server (NTRS)

    Malvin, D. J.; Jones, J. H.; Drake, M. J.

    1986-01-01

    Measurements of solid metal/liquid metal trace element partition coefficients, which are used to interpret the crystallization history of magmatic iron meteorite groups differ greatly between different research groups, using different experimental techniques. Specifically, partition coefficients measured utilizing 'static' experiments which approach equilibrium cannot be reconciled with the results of 'dynamic' experiments which mimic fractional crystallization. We report new tests of our 'static' experimental technique and demonstrate that our methodology yields reliable equilibrium values for Ni, P and Ge partition coefficients. Partition coefficients in the Fe-Ni-S-P system are well matched by interpolation between the Fe-Ni-S and Fe-Ni-P subsystems. In contrast, the predictions of 'dynamic' experiments do not agree with our measurements and, consequently, the ability of 'dynamic' experiments to reproduce iron meteorite Ge vs. Ni fractionation trends successfully must be regarded as fortuitous.

  19. A semi-discrete finite element method for a class of time-fractional diffusion equations

    E-print Network

    HongGuang Sun; Wen Chen; K. Y. Sze

    2013-04-10

    As fractional diffusion equations can describe the early breakthrough and the heavy-tail decay features observed in anomalous transport of contaminants in groundwater and porous soil, they have been commonly employed in the related mathematical descriptions. These models usually involve long-time range computation, which is a critical obstacle for its application, improvement of the computational efficiency is of great significance. In this paper, a semi-analytical method is presented for solving a class of time-fractional diffusion equations which overcomes the critical long-time range computation problem of time fractional differential equations. In the procedure, the spatial domain is discretized by the finite element method which reduces the fractional diffusion equations into approximate fractional relaxation equations. As analytical solutions exist for the latter equations, the burden arising from long-time range computation can effectively be minimized. To illustrate its efficiency and simplicity, four examples are presented. In addition, the method is employed to solve the time-fractional advection-diffusion equation characterizing the bromide transport process in a fractured granite aquifer. The prediction closely agrees with the experimental data and the heavy-tail decay of anomalous transport process is well-represented.

  20. Experimental productivity rate optimization of rare earth element separation through preparative solid phase extraction chromatography.

    PubMed

    Knutson, Hans-Kristian; Max-Hansen, Mark; Jönsson, Christian; Borg, Niklas; Nilsson, Bernt

    2014-06-27

    Separating individual rare earth elements from a complex mixture with several elements is difficult and this is emphasized for the middle elements: Samarium, Europium and Gadolinium. In this study we have accomplished an overloaded one-step separation of these rare earth elements through preparative ion-exchange high-performance liquid chromatography with an bis (2-ethylhexyl) phosphoric acid impregnated column and nitric acid as eluent. An inductively coupled plasma mass spectrometry unit was used for post column element detection. The main focus was to optimize the productivity rate, subject to a yield requirement of 80% and a purity requirement of 99% for each element, by varying the flow rate and batch load size. The optimal productivity rate in this study was 1.32kgSamarium/(hmcolumn(3)), 0.38kgEuropium/(hmcolumn(3)) and 0.81kgGadolinium/(hmcolumn(3)). PMID:24835593

  1. Elemental composition of solid aerosols of different size fraction as exemplified by the Baikal region

    NASA Astrophysics Data System (ADS)

    Filippova, U.

    2012-04-01

    It is preferable to analyse fine aerosol fractions (less than 1 micron) to study remote and regional transfers. In our survey, we used a size fraction of 0.39-0.69 micron which can exist in atmosphere air for several days transferred at distance of hundreds of meters from the source of their origin. A six-phase high volume slit cascade impactor TE-236 (Tisch Environmental Inc.) was used for sampling. Among 20 elements analysed by XRFA-SR, the most informative elements (Ti, Mn, Ni, Cu, Zn, Ga, Ge, Sr, Br, and Pb) were chosen having the highest differences among the sources. These sources with chosen elements were divided into two groups: the first was a group of anthropogenic sources of one type and the second was a group of sources differing from the first one. Concentrations of all elements excluding copper were much higher.in the first group than in the second. The curve shape (ratio of elements) for both groups was also significantly different. Differences of elemental ratio in emissions of anthropogenic sources may serve as an indicator of remote effect of these sources on the background territories, in this case, on the southern basin of Lake Baikal. To analyse relative contribution of the sources to the atmosphere pollution of any region, the ratio between concentrations of chosen elements and Cu concentration was used instead of absolute concentrations. Qualitative relative contribution of the sources to aerosols of Southern Baikal (as exemplified by Listvyanka) can be estimated using multiple linear regression analysis. This analysis was used to estimate the effect of two groups of anthropogenic sources on aerosol composition in the settlement Listvyanka. The composition of fine-disperse aerosol fractions was analysed in two samples collected in Listvyanka in 2009. These two samples were obtained during transfer of air masses from Irkutsk. The first sample (20-21 October 2009) was collected at weak north-western (NW) wind and another sample (27-28 October 2009) - at strong NW wind. These results show that at weak north-western transfer the elemental composition of fine-disperse fraction of aerosols in Listvyanka corresponds to the first group of aerosol sources (80-90%), whereas the percentage of more remote sources makes up about 2-3%.

  2. Concentrations of Elements in Sediments and Selective Fractions of Sediments, and in Natural Waters in Contact with Sediments from Lake Roosevelt, Washington, September 2004

    USGS Publications Warehouse

    Paulson, Anthony J.; Wagner, Richard J.; Sanzolone, Richard F.; Cox, Steven E.

    2006-01-01

    Twenty-eight composite and replicate sediment samples from 8 Lake Roosevelt sites were collected and analyzed for 10 alkali and alkaline earth elements, 2 non-metals, 20 metals, and 4 lanthanide and actinide elements. All elements were detected in all sediment samples except for silver (95 percent of the elements detected for 1,008 analyses), which was detected only in 4 samples. Sequential selective extraction procedures were performed on single composite samples from the eight sites. The percentage of detections for the 31 elements analyzed ranged from 76 percent for the first extraction fraction using a weak extractant to 93 percent for the four-acid dissolution of the sediments remaining after the third sequential selective extraction. Water samples in various degrees of contact with the sediment were analyzed for 10 alkali and alkaline earth elements, 5 non-metals, 25 metals, and 16 lanthanide and actinide elements. The filtered water samples included 10 samples from the reservoir water column at 8 sites, 32 samples of porewater, 55 samples from reservoir water overlying sediments in 8 cores from the site incubated in a field laboratory, and 24 water samples that were filtered after being tumbled with sediments from 8 sites. Overall, the concentrations of only 37 percent of the 6,776 analyses of the 121 water samples were greater than the reporting limit. Selenium, bismuth, chromium, niobium, silver, and zirconium were not detected in any water samples. The percentage of concentrations for the water samples that were above the reporting limit ranged from 14 percent for the lanthanide and actinide elements to 77 percent for the alkali and alkaline earth elements. Concentrations were greater than reporting limits in only 23 percent of the analyses of reservoir water and 29 percent of the analyses of reservoir water overlying incubation cores. In contrast, 47 and 48 percent of the concentrations of porewater and water samples tumbled with sediments, respectively, were greater than the reporting limit.

  3. Rare earth element partitioning between hydrous ferric oxides and acid mine water during iron oxidation

    USGS Publications Warehouse

    Verplanck, P.L.; Nordstrom, D.K.; Taylor, H.E.; Kimball, B.A.

    2004-01-01

    Ferrous iron rapidly oxidizes to Fe (III) and precipitates as hydrous Fe (III) oxides in acid mine waters. This study examines the effect of Fe precipitation on the rare earth element (REE) geochemistry of acid mine waters to determine the pH range over which REEs behave conservatively and the range over which attenuation and fractionation occur. Two field studies were designed to investigate REE attenuation during Fe oxidation in acidic, alpine surface waters. To complement these field studies, a suite of six acid mine waters with a pH range from 1.6 to 6.1 were collected and allowed to oxidize in the laboratory at ambient conditions to determine the partitioning of REEs during Fe oxidation and precipitation. Results from field experiments document that even with substantial Fe oxidation, the REEs remain dissolved in acid, sulfate waters with pH below 5.1. Between pH 5.1 and 6.6 the REEs partitioned to the solid phases in the water column, and heavy REEs were preferentially removed compared to light REEs. Laboratory experiments corroborated field data with the most solid-phase partitioning occurring in the waters with the highest pH. ?? 2004 Elsevier Ltd. All rights reserved.

  4. RARE EARTH ELEMENT OXIDES FOR TRACING SEDIMENT MOVEMENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The development of soil conservation plans and evaluation of spatially distributed erosion models require knowledge of rates of soil loss and sedimentation on different landscape elements and slope positions. Characterization of soil erosion rates and patterns within watersheds is important for the ...

  5. [Study on speciation and fractionation of rare earth eleinents in surface sediments in Gansu, Ningxia and Inner Mongolia sections of Yellow River].

    PubMed

    Liu, Jing-Jun; Lai, Zi-Juan; Liu, Ying

    2013-03-01

    In the present paper, BCR sequential extraction and high resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS) were performed to analyze the speciation contents of 14 kinds of rare earth elements (REE) in the surface sediments from 12 sampling sites (S1-S12) in Gansu, Ningxia and Inner Mongolia Sections of Yellow River, and REE fractionation were also studied. The results indicated that the contents of REE in 12 sediment samples werethe same order. The average contents of 14 rare earth elements were in this order: Ce(66.4)>La(35.8)>Nd(28.6)>Pr(7.88)>Sm(5.87) >Gd(5.01)>Dy (4.53)>Yb(2.86)>Er(2.51)>Eu(1.31)>Ho(0.856)>Tb(0.760)>Tm(0.428)>Lu(0.404), which were similar to the Chinese soil background. The residual fractions of all elements were present at the highest percentages(71.9%-93.9%), which indicated that the bioavailability or environmental impact was low. The percentage of reducible fraction was the lowest, ranged from 0. 20% to 3. 87% with the mean value of 0.83%, while the oxidizable fraction percentage(7.61%) was close to acid-soluble fraction(7.69%). But in Maqu (S12), oxidizable percentage (16.1%) was significantly higher than the acid-soluble fraction (1.73%). Correlation analysis showed that there was a significant positive correlation between total organic carbon (TOC) content and oxidizable percentage, and the correlation coefficients were between 0.763 and 0.914. REE fractionation results showed that: the contents of REE in surface sediments of Gansu, Ningxia and Inner Mongolia Sections of Yellow River were mainly from soil weathering, with light-REE enrichment and Eu depletion. The chondrite-normalized curve implied that La and Ce in Jinshawan (S8) and Baotou-Dengkou (S1) and heavy REE at all the sampling points might have external REE sources. PMID:23705457

  6. Fractionation of highly siderophile and chalcogen elements in components of EH3 chondrites

    NASA Astrophysics Data System (ADS)

    Kadlag, Yogita; Becker, Harry

    2015-07-01

    Abundances of highly siderophile elements (HSE: Re, platinum group elements and Au), chalcogens (Te, Se and S), 187Os/188Os and the major and minor elements Mg, Ca, Mn, Fe, Ni and Co were determined in the components of Sahara 97072 (EH3, find) and Kota Kota (EH3, find) in order to understand the element fractionation processes. In a 187Re-187Os isochron diagram, most magnetic components lie close to the 4.56 Ga IIIA iron meteorite isochron, whereas most other components show deviations from the isochron caused by late redistribution of Re, presumably during terrestrial weathering. Metal- and sulfide rich magnetic fractions and metal-sulfide nodules are responsible for the higher 187Os/188Os in bulk rocks of EH chondrites compared to CI chondrites. The HSE and chalcogens are enriched in magnetic fractions relative to slightly magnetic and nonmagnetic fractions and bulk compositions, indicating that Fe-Ni metal is the main host phase of the HSE in enstatite chondrites. HSE abundance patterns indicate mixing of two components, a CI chondrite like end member and an Au-enriched end member. Because of the decoupled variations of Au from those of Pd or the chalcogens, the enrichment of Au in EH metal cannot be due to metal-sulfide-silicate partitioning processes. Metal and sulfide rich nodules may have formed by melting and reaction of pre-existing refractory element rich material with volatile rich gas. A complex condensation and evaporation history is required to account for the depletion of elements having very different volatility than Au in EH chondrites. The depletions of Te relative to HSE, Se and S in bulk EH chondrites are mainly caused by the depletion of Te in metal. S/Se and S/Mn are lower than in CI chondrites in almost all components and predominantly reflect volatility-controlled loss of sulfur. The latter most likely occurred during thermal processing of dust in the solar nebula (e.g., during chondrule formation), followed by the non-systematic loss of S during terrestrial weathering.

  7. Geochemistry of ultrahigh-pressure anatexis: fractionation of elements in the Kokchetav gneisses during melting at diamond-facies conditions

    NASA Astrophysics Data System (ADS)

    Stepanov, Aleksandr S.; Hermann, Joerg; Korsakov, Andrey V.; Rubatto, Daniela

    2014-05-01

    The Kokchetav complex in Kazakhstan contains garnet-bearing gneisses that formed by partial melting of metasedimentary rocks at ultrahigh-pressure (UHP) conditions. Partial melting and melt extraction from these rocks is documented by a decrease in K2O and an increase in FeO + MgO in the restites. The most characteristic trace element feature of the Kokchetav UHP restites is a strong depletion in light rare earth elements (LREE), Th and U. This is attributed to complete dissolution of monazite/allanite in the melt and variable degree of melt extraction. In contrast, Zr concentrations remain approximately constant in all gneisses. Using experimentally determined solubilities of LREE and Zr in high-pressure melts, these data constrain the temperature of melting to ~1,000 °C. Large ion lithophile elements (LILE) are only moderately depleted in the samples that have the lowest U, Th and LREE contents, indicating that phengite retains some LILE in the residue. Some restites display an increase in Nb/Ta with respect to the protolith. This further suggests the presence of phengite, which, in contrast to rutile, preferentially incorporates Nb over Ta. The trace element fractionation observed during UHP anatexis in the Kokchetav gneisses is significantly different from depletions reported in low-pressure restites, where generally no LREE and Th depletion occurs. Melting at UHP conditions resulted in an increase in the Sm/Nd ratio and a decoupling of the Sm-Nd and Lu-Hf systems in the restite. Further subduction of such restites and mixing with mantle rocks might thus lead to a distinct isotopic reservoir different from the bulk continental crust.

  8. Elemental fractionation in 785 nm picosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Shaheen, M. E.; Gagnon, J. E.; Fryer, B. J.

    2015-05-01

    Elemental fractionation and ICP-MS signal response were investigated for two different pulse width laser beams originating from the same laser system. Femtosecond and picosecond laser beams at pulse widths of 130 fs and 110 ps, respectively, and wavelength of 785 nm were used to ablate NIST 610 synthetic glass and SRM 1107 Naval Brass B at the same spot for 800 to 1000 laser pulses at different repetition rates (5 to 50 Hz). Elemental fractionation was found to depend on repetition rate and showed a trend with femtosecond laser ablation that is opposite to that observed in picosecond laser ablation for most measured isotopes. ICP-MS signal intensity was higher in femtosecond than picosecond LA-ICP-MS in both NIST 610 and naval brass when ablation was conducted under the same fluence and repetition rate. The differences in signal intensity were partly related to differences in particle size distribution between particles generated by femtosecond and picosecond laser pulses and the consequent differences in transport and ionization efficiencies. The main reason for the higher signal intensity resulting from femtosecond laser pulses was related to the larger crater sizes compared to those created during picosecond laser ablation. Elemental ratios measured using 66Zn/63Cu, 208Pb/238U, 232Th/238U, 66Zn/232Th and 66Zn/208Pb were found to change with the number of laser pulses with data points being more scattered in picosecond than femtosecond laser pulses. Reproducibility of replicate measurements of signal intensities, fractionation and elemental ratios was better for fs-LA-ICP-MS (RSD ~ 3 to 6%) than ps-LA-ICP-MS (RSD ~ 7 to 11%).

  9. U.S. trade dispute with China over rare earth elements

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-03-01

    The U.S. government has brought a new trade case against China over rare earth elements (REE) as well as tungsten and molybdenum, President Barack Obama announced on 13 March. Japan and the European Union also have taken similar actions against China about REEs, which are a group of 17 chemically similar metallic elements that are used in a variety of electronic, optical, magnetic, and catalytic applications. REEs are plentiful in the Earth's crust, although China currently has about 37% of the world's reserves and accounts for more than 95% of the world's production of the elements, according to the British Geological Survey. The United States has requested consultations with China at the World Trade Organization (WTO) concerning “China's unfair export restraints on rare earths, as well as tungsten and molybdenum,” the Office of the United States Trade Representative announced in a 13 March statement.

  10. Alkali element depletion by core formation and vaporization on the early Earth

    NASA Technical Reports Server (NTRS)

    Lodders, K.; Fegley, B., Jr.

    1994-01-01

    The depletion of Na, K, Rb, and Cs in the Earth's upper mantle and crust relative to their abundances in chondrites is a long standing problem in geochemistry. Here we consider two commonly invoked mechanisms, namely core formation, and vaporization, for producing the observed depletions. Our models predict that a significant percentage of the Earth's bulk alkali element inventory is in the core (30 percent for Na, 52 percent for K, 74 percent for Rb, and 92 percent for Cs). These predictions agree with independent estimates from nebular volatility trends and (for K) from terrestrial heat flow data. Our models also predict that vaporization and thermal escape during planetary accretion are unlikely to produce the observed alkali element depletion pattern. However, loss during the putative giant impact which formed the Moon cannot be ruled out. Experimental, observational, and theoretical tests of our predictions are also described. Alkali element partitioning into the Earth's core was modeled by assuming that alkali element partitioning during core formation on the aubrite parent body (APB) is analogous to that on the early Earth. The analogy is reasonable for three reasons. First, the enstatite meteorites are the only known meteorites with the same oxygen isotope systematics as the Earth-Moon system. Second, the large core size of the Earth and the V depletion in the mantle requires accretion from planetesimals as reduced as the enstatite chondrites. Third, experimental studies of K partitioning between silicate and metal plus sulfide show that more K goes into the metal plus sulfide at higher pressures than at one atmosphere pressure. Thus partitioning in the relatively low pressure natural laboratory of the APB is a good guide to alkali elemental partitioning during the growth of the Earth.

  11. Addressing Rare-Earth Element Criticality: An Example from the Aviation Industry

    NASA Astrophysics Data System (ADS)

    Ku, Anthony Y.; Dosch, Christopher; Grossman, Theodore R.; Herzog, Joseph L.; Maricocchi, Antonio F.; Polli, Drew; Lipkin, Don M.

    2014-11-01

    Rare-earth (RE) elements are enablers for a wide range of technologies, including high-strength permanent magnets, energy-efficient lighting, high-temperature thermal barrier coatings, and catalysts. While direct material substitution is difficult in many of these applications because of the specific electronic, optical, or electrochemical properties imparted by the individual rare-earth elements, we describe an example from the aviation industry where supply chain optimization may be an option. Ceramic matrix composite engine components require environmental barrier coatings (EBCs) to protect them from extreme temperatures and adverse reactions with water vapor in the hot gas path. EBC systems based on rare-earth silicates offer a unique combination of environmental resistance, thermal expansion matching, thermal conductivity, and thermal stability across the service temperature window. Several pure rare-earth silicates and solid solutions have been demonstrated in EBC applications. However, all rely on heavy rare-earth elements (HREEs) for phase stability. This article considers the possibility of using separation tailings containing a mixture of HREEs as a source material in lieu of using the high-purity HREE oxides. This option arises because the desired properties of RE-silicate EBCs derive from the average cation size rather than the electronic properties of the individual rare-earth cations. Because separation tailings have not incurred the costs associated with the final stages of separation, they offer an economical alternative to high-purity oxides for this emerging application.

  12. Addressing Rare-Earth Element Criticality: An Example from the Aviation Industry

    NASA Astrophysics Data System (ADS)

    Ku, Anthony Y.; Dosch, Christopher; Grossman, Theodore R.; Herzog, Joseph L.; Maricocchi, Antonio F.; Polli, Drew; Lipkin, Don M.

    2014-09-01

    Rare-earth (RE) elements are enablers for a wide range of technologies, including high-strength permanent magnets, energy-efficient lighting, high-temperature thermal barrier coatings, and catalysts. While direct material substitution is difficult in many of these applications because of the specific electronic, optical, or electrochemical properties imparted by the individual rare-earth elements, we describe an example from the aviation industry where supply chain optimization may be an option. Ceramic matrix composite engine components require environmental barrier coatings (EBCs) to protect them from extreme temperatures and adverse reactions with water vapor in the hot gas path. EBC systems based on rare-earth silicates offer a unique combination of environmental resistance, thermal expansion matching, thermal conductivity, and thermal stability across the service temperature window. Several pure rare-earth silicates and solid solutions have been demonstrated in EBC applications. However, all rely on heavy rare-earth elements (HREEs) for phase stability. This article considers the possibility of using separation tailings containing a mixture of HREEs as a source material in lieu of using the high-purity HREE oxides. This option arises because the desired properties of RE-silicate EBCs derive from the average cation size rather than the electronic properties of the individual rare-earth cations. Because separation tailings have not incurred the costs associated with the final stages of separation, they offer an economical alternative to high-purity oxides for this emerging application.

  13. [Leaching of Rare Earth Elements from Coal Ashes Using Acidophilic Chemolithotrophic Microbial Communities].

    PubMed

    Muravyov, M I; Bulaev, A G; Melamud, V S; Kondrat'eva, T F

    2015-01-01

    A method for leaching rare earth elements from coal ash in the presence of elemental sulfur using communities of acidophilic chemolithotrophic microorganisms was proposed. The optimal parameters determined for rare element leaching in reactors were as follows: temperature, 45 degrees C; initial pH, 2.0; pulp density, 10%; and the coal ash to elemental sulfur ratio, 10 : 1. After ten days of leaching, 52.0, 52.6, and 59.5% of scandium, yttrium, and lanthanum, respectively, were recovered. PMID:26263628

  14. Potential toxic element fractionation and phytoavailability assessment in technosoils from former smelting and mining areas

    NASA Astrophysics Data System (ADS)

    Qasim, Bashar; Motelica-Heino, Mikael

    2014-05-01

    High metal and metalloid concentrations in soils have negative effects on terrestrial ecosystems and generate potential health risk. Mining and smelting activities are the major source of metal contamination by release a huge amounts of these potentially toxic elements (PTE) into the environment. Since the determination of the total concentration of PTE in soils does not give sufficient information about their mobility and toxicity, additional information on their bioavailability and their chemical speciation is required. Our study aimed at reporting the chemical fractionation and phytoavailability assessment of several PTE (Zn, Pb, Cd, As and Sb) in contaminated technosoils of two former smelting and mining areas. Soil samples were taken from a metallophyte grassland contaminated with Zn, Pb and Cd located at Mortagne - du -Nord (MDN) (North France) and from a former mining settling basin contaminated with As, Pb and Sb located at la Petite Faye (LPF) (Limoges district, France). Two sequential extraction schemes were used to evaluate the PTE speciation in various technosoils as operationally defined fractions. The extraction schemes used in this study were the Tessier's scheme and a modified BCR scheme. The fractions were rearranged into four equivalent fractions defined as acid soluble, reducible, oxidisable and residual fraction. To assess the metals and metalloids phytoavailability a series of selective single extraction procedures (CaCl2, NaNO3, NH4NO3, DTPA and EDTA) were used together with short-term germination tests with dwarf beans whose primary leaves were analyzed for their PTE concentration after 21 days of sowing under controlled conditions (16h light/8h darkness regime, 25°C/21°C, relative humidity of 55 - 65% and photon flux of 150 ?E m-2s-1). Our results indicates that Zn, Cd and Pb were mainly associated with the acid soluble and reducible fractions for the MDN site, while As, Sb and Pb were mostly associated with residual fraction for the LPF site. The extraction capacity of the PTE followed the order: EDTA>DTPA>NH4NO3>CaCl2> NaNO3 for both studied locations. Pearson correlation coefficient analysis between the concentrations of PTE accumulated in the bean primary leaves with their extractable concentrations showed a positive significant correlation with dilute CaCl2 and unbuffered nitrate solutions extraction procedures. In contrast, for all studied elements, except for Pb, the complexing and chelating extractants (e.g. EDTA and DTPA) exhibited poor correlation with the dwarf bean leaves concentrations.

  15. Spatiotemporal correlations in Earth's temperature field from fractional stochastic-diffusive energy balance models

    NASA Astrophysics Data System (ADS)

    Rypdal, Kristoffer; Rypdal, Martin; Fredriksen, Hege-Beate

    2015-04-01

    In the Earth temperature field, spatiotemporal long-range dependence is usually explained as a result of nonlinear cross-scale coupling and cascading. In this contribution we challenge that paradigm, demonstrating that the observed correlation structure can arise from simple, linear, conceptual models. A two-dimensional stochastic-diffusive energy balance model (EBM) formulated on a sphere by G. R. North et al., J. Climate, 24:5850-5862, 2011, is explored and generalized. We compute instantaneous and frequency-dependent spatial autocorrelation functions, and local temporal power spectral densities for local sites and for spatially averaged signal up to the global scale. On time scales up to the relaxation time scale given by the effective heat capacities of the ocean mixed layer and land surface, respectively, we obtain scaling features reminiscent of what can be derived from the observed temperature field. On longer time scales, however, the EBM predicts a transition to a white-noise scaling, which is not reflected in the observed records. We propose and explore a fractional generalization (FEBM), which can be considered as a spatiotemporal version of the zero-dimensional, long-memory EBM of M. Rypdal and K. Rypdal, J. Climate, 27:5240-5258, 2014. The fractional equation introduces a power-law (rather than exponential) impulse response representing the delayed action due to the slow heat exchange between the mixed layer and the deep ocean. It is demonstrated that this generalized model describes qualitatively the main spatiotemporal correlation characteristics of the temperature field derived from instrumental data and from a 500 yr control run of the Nor-ESM model. For instance, the FEBM implies temporal power-law spectra where the spectral exponent for globally averaged temperature is twice that of local temperatures, and spatial autocorrelation lengths increases with time scale, in good agreement with the Nor-ESM simulations. It also reproduces the long-time response to a step-function forcing in the Nor-ESM model.

  16. Determination of rare-earth elements in Luna 16 regolith sample by chemical spectral method

    NASA Technical Reports Server (NTRS)

    Stroganova, N. S.; Ryabukhin, V. A.; Laktinova, N. V.; Ageyeva, L. V.; Galkina, I. P.; Gatinskaya, N. G.; Yermakov, A. N.; Karyakin, A. V.

    1974-01-01

    An analysis was made of regolith from layer A of the Luna 16 sample for rare earth elements, by a chemical spectral method. Chemical and ion exchange concentrations were used to determine the content of 12 elements and Y at the level 0.001 to 0.0001 percent with 10 to 15 percent reproducibility of the emission determination. Results within the limits of reproducibility agree with data obtained by mass spectra, activation, and X-ray fluorescent methods.

  17. The behaviour of trace and rare earth elements (REE) during hydrothermal alteration in the Rangan area (Central Iran)

    NASA Astrophysics Data System (ADS)

    Parsapoor, A.; Khalili, M.; Mackizadeh, M. A.

    2009-02-01

    The rhyolitic dome in the Rangan area has been subjected to hydrothermal alterations by two different systems, (1) A fossil magmatic-hydrothermal system with a powerful thermal engine of a deep monzodioritic magma, (2) An active hydrothermal system dominated by meteoric water. Based on mineralogical and geochemical studies, three different alteration facies have been identified (phyllic, advanced argillic and silicic) with notable differences in REE and other trace elements behaviour. In the phyllic alteration zone with assemblage minerals such as sericite, pyrite, quartz, kaolinite, LREE are relatively depleted whereas HREE are enriched. The advanced argillic zone is identified by the presence of alunite-jarosite and pyrophyllite as well as immobility of LREE and depletion in HREE. In the silicic zone, most of LREE are depleted but HREE patterns are unchanged compared to their fresh rock equivalents. All the REE fractionation ratios (La/Yb) cn, (La/Sm) cn, (Tb/Yb) cn, (Ce/Ce ?) cn and (Eu/Eu ?) cn are low in the phyllic altered facies. (Eu/Eu ?) cn in both advanced and silicic facies is low too. In all alteration zones, high field strength elements (HFSE) (e.g. Ti, Zr, Nb) are depleted whereas transition elements (e.g. V, Cr, Co, Ni, Fe) are enriched. Geochemically speaking, trace and rare earth elements behave highly selective in different facies.

  18. Composition of the earth's upper mantle. I - Siderophile trace elements in ultramafic nodules

    NASA Technical Reports Server (NTRS)

    Morgan, J. W.; Wandless, G. A.; Petrie, R. K.; Irving, A. J.

    1981-01-01

    The considered investigation is concerned with a reexamination of the question of the distribution of siderophile elements in the earth's upper mantle, taking into account a more unified data base which is now available. A comprehensive suite of ultramafic inclusions was collected as part of the Basaltic Volcanism Study Project and has been analyzed by instrument neutron activation analysis for major, minor, and some lithophile trace elements. In addition, 18 of these rocks and the important sheared garnet lherzolite PHN 1611 have been analyzed by means of radiochemical neutron activation analysis for 7 siderophile elements (Au, Ge, Ir, Ni, Os, Pd, and Re) and 9 volatile elements (Ag, Bi, Cd, In, Sb, Se, Te, Tl, and Zn). The siderophile element data reveal interesting inter-element correlations, which were not apparent from the compiled abundance tables of Ringwood and Kesson (1976) and Chou (1978).

  19. Structure and evolution of super-Earth to super-Jupiter exoplanets: I. heavy element enrichment in the interior

    E-print Network

    I. Baraffe; G. Chabrier; T. Barman

    2008-02-13

    We examine the uncertainties in current planetary models and we quantify their impact on the planet cooling histories and mass-radius relationships. These uncertainties include (i) the differences between the various equations of state used to characterize the heavy material thermodynamical properties, (ii) the distribution of heavy elements within planetary interiors, (iii) their chemical composition and (iv) their thermal contribution to the planet evolution. Our models, which include a gaseous H/He envelope, are compared with models of solid, gasless Earth-like planets in order to examine the impact of a gaseous envelope on the cooling and the resulting radius. We find that for a fraction of heavy material larger than 20% of the planet mass, the distribution of the heavy elements in the planet's interior affects substantially the evolution and thus the radius at a given age. For planets with large core mass fractions ($\\simgr$ 50%), such as the Neptune-mass transiting planet GJ436b, the contribution of the gravitational and thermal energy from the core to the planet cooling history is not negligible, yielding a $\\sim$ 10% effect on the radius after 1 Gyr. We show that the present mass and radius determinations of the massive planet Hat-P-2b require at least 200 $\\mearth$ of heavy material in the interior, at the edge of what is currently predicted by the core-accretion model for planet formation. We show that if planets as massive as $\\sim$ 25 $\\mjup$ can form, as predicted by improved core-accretion models, deuterium is able to burn in the H/He layers above the core, even for core masses as large as $\\sim$ 100 $\\mearth$. We provide extensive grids of planetary evolution models from 10 $\\mearth$ to 10 M$_{\\rm Jup}$, with various fractions of heavy elements.

  20. The Formation of Sulfate and Elemental Sulfur Aerosols Under Varying Laboratory Conditions: Implications for Early Earth

    NASA Technical Reports Server (NTRS)

    DeWitt, H. Langley; Hasenkopf, Christa A.; Trainer, Melissa G.; Farmer, Delphine K.; Jimenez, Jose L.; McKay, Christopher P.; Toon, Owen B.; Tolbert, Margaret A.

    2010-01-01

    The presence of sulfur mass-independent fractionation (S-MIF) in sediments more than 2.45 x 10(exp 9) years old is thought to be evidence for an early anoxic atmosphere. Photolysis of sulfur dioxide (SO2) by UV light with lambda < 220 nm has been shown in models and some initial laboratory studies to create a S-MIF; however, sulfur must leave the atmosphere in at least two chemically different forms to preserve any S-MIF signature. Two commonly cited examples of chemically different sulfur species that could have exited the atmosphere are elemental sulfur (S8) and sulfuric acid (H2S04) aerosols. Here, we use real-time aerosol mass spectrometry to directly detect the sulfur-containing aerosols formed when SO2 either photolyzes at wavelengths from 115 to 400 nm, to simulate the UV solar spectrum, or interacts with high-energy electrons, to simulate lightning. We found that sulfur-containing aerosols form under all laboratory conditions. Further, the addition of a reducing gas, in our experiments hydrogen (H2) or methane (CH4), increased the formation of S8. With UV photolysis, formation of S8 aerosols is highly dependent on the initial SO2 pressure; and S8 is only formed at a 2% SO2 mixing ratio and greater in the absence of a reductant, and at a 0.2% SO2 mixing ratio and greater in the presence of 1000 ppmv CH4. We also found that organosulfur compounds are formed from the photolysis of CH4 and moderate amounts of SO2, The implications for sulfur aerosols on early Earth are discussed.

  1. Factors affecting the rare earth element compositions in massive sulfides from deep-sea hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Zeng, Zhigang; Ma, Yao; Yin, Xuebo; Selby, David; Kong, Fancui; Chen, Shuai

    2015-09-01

    To reconstruct the evolution of ore-forming fluids and determine the physicochemical conditions of deposition associated with seafloor massive sulfides, we must better understand the sources of rare earth elements (REEs), the factors that affect the REE abundance in the sulfides, and the REE flux from hydrothermal fluids to the sulfides. Here we examine the REE profiles of 46 massive sulfide samples collected from seven seafloor hydrothermal systems. These profiles feature variable total REE concentrations (37.2-4092 ppb) and REE distribution patterns (LaCN/LuCN ratios = 2.00-73.8; (Eu/Eu*)CN ratios = 0.34-7.60). The majority of the REE distribution patterns in the sulfides are similar to those of vent fluids, with the sulfides also exhibiting light REE enrichment. We demonstrate that the variable REE concentrations, Eu anomalies, and fractionation between light REEs and heavy REEs in the sulfides exhibit a relationship with the REE properties of the sulfide-forming fluids and the massive sulfide chemistry. Based on the sulfide REE data, we estimate that modern seafloor sulfide deposits contain approximately 280 t of REEs. According to the flux of hydrothermal fluids at mid-ocean ridges (MORs) and an average REE concentration of 3 ng/g in these fluids, hydrothermal vents at MORs alone transport more REEs (>360 t) to the oceans over the course of just 2 years than the total quantity of REEs in seafloor sulfides. The excess REEs (i.e., the quantity not captured by massive sulfides) may be transported away from the systems and become bound in sulfate deposits and metalliferous sediments.

  2. Radioluminescence and thermoluminescence of rare earth element and phosphorus-doped zircon

    SciTech Connect

    Karali, T.; Can, N.; Townsend, P.D.; Rowlands, A.P.; Hanchar, J.M.

    2000-06-01

    The radioluminescence and thermoluminescence spectra of synthetic zircon crystals doped with individual trivalent rare earth element (REE) ions (Pr, Sm, Eu, Gd, Dy, Ho, Er, and Yb) and P are reported in the temperature range 25 to 673 K. Although there is some intrinsic UV/blue emission from the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the REE{sup 3+} states. The shapes of the glow curves are different for each dopant, and there are distinct differences between glow peak temperatures for different rare-earth lines of the same element. Within the overall set of signals there are indications of linear trends in which some glow peak temperatures vary as a function of the ionic size of the rare earth ions. The temperature shifts of the peaks are considerable, up to 200{degree}, and much larger than those cited in other rare-earth-doped crystals of LaF{sub 3} and Bi{sub 4}Ge{sub 3}O{sub 12}. The data clearly suggest that the rare-earth ions are active both in the trapping and luminescence steps, and hence the TL occurs within localized defect complexes that include REE{sup 3+} ions.

  3. Rare earth elements activate endocytosis in plant cells Lihong Wanga,b,1

    E-print Network

    Deng, Xing-Wang

    Rare earth elements activate endocytosis in plant cells Lihong Wanga,b,1 , Jigang Lic,d,1 , Qing on the plasma membrane in the form of nanoscale particles, and then entered the cells by endocytosis. Consistently, REEs activated endocytosis in plant cells, which may be the cellular basis of REE actions

  4. Interactions between exogenous rare earth elements and phosphorus leaching in packed soil columns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rare earth elements (REEs) increasingly used in agriculture as an amendment for crop growth may help to lessen environmental losses of phosphorus (P) from heavily fertilized soils. The vertical transport characteristics of P and REEs, lanthanum (La), neodymium (Nd), samarium (Sm), and cerium (Ce), w...

  5. A LOW-COST RARE EARTH ELEMENTS RECOVERY TECHNOLOGY - PHASE I

    EPA Science Inventory

    Physical Sciences, Inc., and the University of Kentucky Center for Applied Energy Research propose to develop a unique enabling technology to significantly reduce U.S. dependency for Rare Earth Elements (REE) on foreign suppliers and our global competitors. Our innovation...

  6. SEDIMENT REWORKING AND TRANSPORT IN EASTERN LAKE SUPERIOR: IN SITU RARE EARTH ELEMENT TRACER STUDIES

    EPA Science Inventory

    A rare earth element (REE) tracer pellet was deployed at the floor of the Ile Parisienne basin of eastern Lake Superior to measure representative sediment reworking and transport processes in the benthic boundary layer of the prnfundal Great Lakes. Samarium oxide, a high neutron-...

  7. Tracing sediment movement on semi-arid watershed using Rare Earth Elements 1988

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A multi-tracer method employing rare earth elements (REE) was used to determine sediment yield and to track sediment movement in a small semiarid watershed. A 0.33 ha watershed near Tombstone, AZ was divided into five morphological units, each tagged with one of five REE oxides. Relative contributi...

  8. Preliminary study on using rare earth elements to trace non-point source phosphorous loss

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The environmental fate of phosphorus (P) is of concern as P is a primary cause of freshwater eutrophication. Rare earth elements (REEs) have been successfully used in the analysis of soil erosion and pollutant sources, as well as in the analysis of mineral genesis. To better understand the potential...

  9. Finite groups with an automorphism cubing a large fraction of elements

    E-print Network

    Hegarty, Peter

    2007-01-01

    We investigate the possible structures imposed on a finite group by its possession of an automorphism sending a large fraction of the group elements to their cubes, the philosophy being that this should force the group to be, in some sense, close to abelian. We prove two theorems. In the first, we completely classify all finite groups with an automorphism cubing more than half their elements. All such groups are either nilpotent class 2 or have an abelian subgroup of index at most 2. For our second theorem we show that, if a group possesses an automorphism sending more than 4/15 of its elements to their cubes, then it must be solvable. The group A_5 shows that this result is best possible. Both our main findings closely parallel results of previous authors on finite groups possessing an automorphism which inverts many group elements. The technicalities of the new proofs are somewhat more subtle, and also throw up a nice connection to a basic problem in combinatorial number theory, namely the study of subsets ...

  10. Elemental analysis of size-fractionated particulate matter sampled in Göteborg, Sweden

    NASA Astrophysics Data System (ADS)

    Wagner, Annemarie; Boman, Johan; Gatari, Michael J.

    2008-12-01

    The aim of the study was to investigate the mass distribution of trace elements in aerosol samples collected in the urban area of Göteborg, Sweden, with special focus on the impact of different air masses and anthropogenic activities. Three measurement campaigns were conducted during December 2006 and January 2007. A PIXE cascade impactor was used to collect particulate matter in 9 size fractions ranging from 16 to 0.06 µm aerodynamic diameter. Polished quartz carriers were chosen as collection substrates for the subsequent direct analysis by TXRF. To investigate the sources of the analyzed air masses, backward trajectories were calculated. Our results showed that diurnal sampling was sufficient to investigate the mass distribution for Br, Ca, Cl, Cu, Fe, K, Sr and Zn, whereas a 5-day sampling period resulted in additional information on mass distribution for Cr and S. Unimodal mass distributions were found in the study area for the elements Ca, Cl, Fe and Zn, whereas the distributions for Br, Cu, Cr, K, Ni and S were bimodal, indicating high temperature processes as source of the submicron particle components. The measurement period including the New Year firework activities showed both an extensive increase in concentrations as well as a shift to the submicron range for K and Sr, elements that are typically found in fireworks. Further research is required to validate the quantification of trace elements directly collected on sample carriers.

  11. Coronal Sources, Elemental Fractionation, and Release Mechanisms of Heavy Ion Dropouts in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Weberg, Micah J.; Lepri, Susan T.; Zurbuchen, Thomas H.

    2015-03-01

    The elemental abundances of heavy ions (masses larger than He) in the solar wind provide information about physical processes occurring in the corona. Additionally, the charge state distributions of these heavy ions are sensitive to the temperature profiles of their respective source regions in the corona. Heavy ion dropouts are a relatively new class of solar wind events identified by both elemental and ionic charge state distributions. We have shown that their origins lie in large, closed coronal loops where processes such as gravitational settling dominate and can cause a mass-dependent fractionation pattern. In this study we consider and attempt to answer three fundamental questions concerning heavy ion dropouts: (1) "where are the source loops located in the large-scale corona?"; (2) "how does the interplay between coronal processes influence the end elemental abundances?"; and (3) "what are the most probable release mechanisms"? We begin by analyzing the temporal and spatial variability of heavy ion dropouts and their correlation with heliospheric plasma and magnetic structures. Next we investigate the ordering of the elements inside dropouts with respect to mass, ionic charge state, and first ionization potential. Finally, we discuss these results in the context of the prevailing solar wind theories and the processes they posit that may be responsible for the release of coronal plasma into interplanetary space.

  12. Rare earth element evidence for the petrogenesis of the banded series of the Stillwater Complex, Montana, and its anorthosites

    USGS Publications Warehouse

    Loferski, P.J.; Arculus, R.J.; Czamanske, G.K.

    1994-01-01

    A rare earth element (REE) study was made by isotope-dilution mass spectrometry of plagioclase separates from a variety of cumulates stratigraphically spanning the Banded series of the Stillwater Complex, Montana. Evaluation of parent liquid REE patterns, calculated on the basis of published plagioclase-liquid partition coefficients, shows that the range of REE ratios is too large to be attributable to fractionation of a single magma type. At least two different parental melts were present throughout the Banded series. This finding supports hypotheses of previous workers that the Stillwater Complex formed from two different parent magma types, designated the anorthosite- or A-type liquid and the ultramafic- or U-type liquid. -from Authors

  13. Rare-earth elements in hot brines (165 to 190 degree C) from the Salton Sea geothermal field

    SciTech Connect

    Lepel, E.A.; Laul, J.C.; Smith, M.R.

    1988-01-01

    Rare-earth element (REE) concentrations are important indicators for revealing various chemical fractionation processes (water/rock interactions) and source region geochemistry. Since the REE patterns are characteristic of geologic materials (basalt, granite, shale, sediments, etc.) and minerals (K-feldspar, calcite, illite, epidote, etc.), their study in geothermal fluids may serve as a geothermometer. The REE study may also enable us to address the issue of groundwater mixing. In addition, the behavior of the REE can serve as analogs of the actinides in radioactive waste (e.g., neodymium is an analog of americium and curium). In this paper, the authors port the REE data for a Salton Sea Geothermal Field (SSGF) brine (two aliquots: port 4 at 165{degree}C and port 5 at 190{degree}C) and six associated core samples.

  14. Rare earth and trace elements of fossil vertebrate bioapatite as palaeoenvironmental and sedimentological proxies

    NASA Astrophysics Data System (ADS)

    Žigait?, Živil?; Fadel, Alexandre; Pérez-Huerta, Alberto; Jeffries, Teresa

    2015-04-01

    Rare earth (REE) and trace element compositions of fossil vertebrate dental microremains have been studied in Silurian and Devonian vertebrate dental scales and spines in-situ, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Samples were selected from the well-known Silurian bone beds of Vesiku and Ohesaare in Saaremaa island of Estonia, and a number of Lower Devonian localities from Spitsbergen (Svalbard), Andrée Land group. Biomineral preservation was assessed using spot semi-quantitative elemental chemistry (SEM-EDS) and electron back-scatter difractometry (EBSD) for cristallinity imaging. The obtained PAAS shale-normalised REE concentrations were evaluated using basic geochemical calculations and quantifications. The REE patterns from the Lower Devonian vertebrate apatite from Andrée Land, Spitsbergen (Wood Bay and Grey Hœk formations) did not show any recognisable taxon-specific behavior, but had rather well expressed differences of REE compositions related to biomineral structure and sedimentary settings, suggesting REE instead to reflect burial environments and sedimentological history. The Eu anomaly recorded in two of the studied localities but not in the other indicate different taphonomic conditions and palaeoenvironment, while La/Sm, La/Yb ratios sugeest considerable influence of terrestrial freshwater during the early diagenesis. The La/Yb and La/Sm plots also agree with the average REE concentrations, reflecting domination of the adsoption over substitution as principal REE uptake mechanism in the fossils which had significantly lower overall REE concentrations, and vice versa. Vesiku (Homerian, Wenlock) microremains yielded very uniform REE patterns with slightly lower overall REE concentrations in enameloid than in dentine, with strong enrichment in middle REE and depletion in heavy REE. Negative Europium (Eu) anomaly was pronounced in all the profiles, but Cerium (Ce) anomalies were not detected suggesting possible suboxic to anoxic conditions of the bottom and pore waters during the formation of Vesiku bone bed. In Ohesaare (Pridoli), the REE compositions were nearly identical across all the morphotypes and histologies of acanthodian microremains showing flat REE patterns with slight depletion in HREE. There were no visible enrichment in MREE, indicating relatively good preservation of original bioapatite and likely absence of any pronounced fractionated REE incorporation during later stages of diagenesis. The shale normalised (La/Yb)SN and (La/Sm)SN REE ratio compilations showed addsorption as dominating REE uptake mechanism across all the studied microfossils. The absence of well-defined Ce anomaly suggest oxic palaeoseawater conditions, which agrees with existing interpretations of Ohesaare sequence as high-energy shoal and regressive open ocean sedimentary environment.

  15. Rare Earth Element Measurements of Melilite and Fassaite in Allende Cai by Nanosims

    NASA Technical Reports Server (NTRS)

    Ito, M.; Messenger, Scott

    2009-01-01

    The rare earth elements (REEs) are concentrated in CAIs by approx. 20 times the chondritic average [e.g., 1]. The REEs in CAIs are important to understand processes of CAI formation including the role of volatilization, condensation, and fractional crystallization [1,2]. REE measurements are a well established application of ion microprobes [e.g., 3]. However the spatial resolution of REE measurements by ion microprobe (approx.20 m) is not adequate to resolve heterogeneous distributions of REEs among/within minerals. We have developed methods for measuring REE with the NanoSIMS 50L at smaller spatial scales. Here we present our initial measurements of REEs in melilite and fassaite in an Allende Type-A CAI with the JSC NanoSIMS 50L. We found that the key parameters for accurate REE abundance measurements differ between the NanoSIMS and conventional SIMS, in particular the oxide-to-element ratios, the relative sensitivity factors, the energy distributions, and requisite energy offset. Our REE abundance measurements of the 100 ppm REE diopside glass standards yielded good reproducibility and accuracy, 0.5-2.5 % and 5-25 %, respectively. We determined abundances and spatial distributions of REEs in core and rim within single crystals of fassaite, and adjacent melilite with 5-10 m spatial resolution. The REE abundances in fassaite core and rim are 20-100 times CI abundance but show a large negative Eu anomaly, exhibiting a well-defined Group III pattern. This is consistent with previous work [4]. On the other hand, adjacent melilite shows modified Group II pattern with no strong depletions of Eu and Yb, and no Tm positive anomaly. REE abundances (2-10 x CI) were lower than that of fassaite. These patterns suggest that fassaite crystallized first followed by a crystallization of melilite from the residual melt. In future work, we will carry out a correlated study of O and Mg isotopes and REEs of the CAI in order to better understand the nature and timescales of its formation process and subsequent metamorphic history.

  16. Heavy metals and rare earth elements source-sink in some Egyptian cigarettes as determined by neutron activation analysis.

    PubMed

    Nada, A; Abdel-Wahab, M; Sroor, A; Abdel-Haleem, A S; Abdel-Sabour, M F

    1999-07-01

    Heavy metals and rare earth elements in two types of cigarettes were studied. The contents of trace elements were determined by using delayed neutron activation analysis. In the present study 11 elements have been detected in popular and fine brand cigarettes marketed in Egypt. Evaluation of these elements with their potential hazards for smokers is briefly discussed. The material balance (source and sink) for each element was determined. Also the ratio of element recovery to the total amount was assessed. PMID:10376325

  17. The group separation of the rare-earth elements and yttrium from geologic materials by cation-exchange chromatography

    USGS Publications Warehouse

    Crock, J.G.; Lichte, F.E.; Wildeman, T.R.

    1984-01-01

    Demand is increasing for the determination of the rare-earth elements (REE) and yttrium in geologic materials. Due to their low natural abundance in many materials and the interferences that occur in many methods of determination, a separation procedure utilizing gradient strong-acid cation-exchange chromatography is often used to preconcentrate and isolate these elements from the host-rock matrix. Two separate gradient strong-acid cation-exchange procedures were characterized and the major elements as well as those elements thought to provide the greatest interference for the determination of the REE in geologic materials were tested for separation from the REE. Simultaneous inductively coupled argon plasma-atomic emission spectroscopy (ICAP-AES) measurements were used to construct the chromatograms for the elution studies, allowing the elution patterns of all the elements of interest to be determined in a single fraction of eluent. As a rock matrix, U.S. Geological Survey standard reference BCR-1 basalt was digested using both an acid decomposition procedure and a lithium metaborate fusion. Hydrochloric and nitric acids were tested as eluents and chromatograms were plotted using the ICAP-AES data; and we observed substantial differences in the elution patterns of the REE and as well as in the solution patterns of Ba, Ca, Fe and Sr. The nitric acid elution required substantially less eluent to elute the REE and Y as a group when compared to the hydrochloric acid elution, and provided a clearer separation of the REE from interfering and matrix elements. ?? 1984.

  18. Behaviour of zirconium, niobium, yttrium and the rare earth elements in the Thor Lake rare-metal

    E-print Network

    Behaviour of zirconium, niobium, yttrium and the rare earth elements in the Thor Lake rare-metal © Emma Rebecca Sheard, 2010 #12;i ABSTRACT The Thor Lake rare-metal (Zr, Nb, Y, REE, Ta, Be, Ga) deposit and the heavy rare earth elements in the world. Much of the potentially economic mineralization was concentrated

  19. Inter-element fractionation of highly siderophile elements in the Tonga Arc due to flux melting of a depleted source

    NASA Astrophysics Data System (ADS)

    Dale, Christopher W.; Macpherson, Colin G.; Pearson, D. Graham; Hammond, Samantha J.; Arculus, Richard J.

    2012-07-01

    Highly siderophile element concentrations (HSEs: Os, Ir, Ru, Pt, Pd, and Re) have been determined for a suite of fresh, submarine mafic lavas from the northern Tonga Arc front and the nascent backarc Fonualei Spreading Centre (FSC). Prior melt depletion of the Tongan mantle wedge combined with a high degree of fluid fluxed melting is thought to have produced boninitic magmas at several arc and FSC locations. As such, this arc system provides an opportunity to assess the fluid mobility of HSEs and to investigate the effects of fluid-induced melting and prior melt depletion on HSE behaviour during both mantle melting and magma evolution. Tongan lavas display extreme enrichment of Pt (2.5-32 ng/g) and Pd over Os (0.002-0.6 ng/g), Ir, and Ru, significantly greater than basalts from mid-ocean ridges. Magma evolution increases the degree of fractionation, resulting in the highest recorded Pt/Ru ratios (>300) in arc front samples with MgO <8 wt.%. This increasing fractionation is due to the mild incompatibility of Pt and Pd, and concurrent compatibility of Ru, during sulphide undersaturated magma evolution. However, the fractionation of Pt and Pd from Os, Ir, and Ru is observed in the highest MgO samples, indicating source inheritance. Prior melt depletion of the mantle and elevated oxygen fugacity both increase the likelihood of complete consumption of sulphide in the source during melting, which typically leads to melts with high concentrations of all the HSE. Indeed, modelling indicates that 25% aggregate partial melting of a depleted MORB-mantle source, proposed for the Tonga Arc, will lead to complete base-metal sulphide consumption unless there is considerable addition of S by the slab flux (at least 200 ?g/g). Although source enrichment of Pt, Pd, and Re by slab fluids may take place, the fractionation of Pt and Pd from Os, Ir, and Ru can largely be explained by relatively low-temperature, yet high-degree, melting of fluid-fluxed melt-depleted mantle. The high Pt and Pd contents can be produced by the exhaustion of sulphide in the source, while the presence of Ru-Os-(Ir) alloys or sulphides (e.g. laurite) associated with Cr-spinel can explain Os, Ir, and Ru retention in the source residue. Such phases have been documented in fluid-fluxed sub-arc mantle from ophiolites. Osmium isotopes co-vary negatively with Os abundance and thus appear to be dominated by shallow level contamination. The most Os-rich samples, however, have 187Os/188Os ratios (0.126-0.132) which are typical of DMM and MORB, suggesting an indistinguishable flux of radiogenic Os from the slab. The significant fractionation of Pt and Re from Os in arc settings will lead, over time, to elevated 186Os and 187Os which may be relevant to the observed enrichments of these isotopes in some mantle regions. In addition, the differing behaviour of Ru and Ir, and the implication of a mantle source containing Ru-rich microphases, may have consequences for the estimation of the HSE composition of primitive upper mantle.

  20. Surface kinetic model for isotopic and trace element fractionation during precipitation of calcite from aqueous solution

    SciTech Connect

    DePaolo, D.

    2010-10-15

    A surface reaction kinetic model is developed for predicting Ca isotope fractionation and metal/Ca ratios of calcite as a function of rate of precipitation from aqueous solution. The model is based on the requirements for dynamic equilibrium; i.e. proximity to equilibrium conditions is determined by the ratio of the net precipitation rate (R{sub p}) to the gross forward precipitation rate (R{sub f}), for conditions where ionic transport to the growing crystal surface is not rate-limiting. The value of R{sub p} has been experimentally measured under varying conditions, but the magnitude of R{sub f} is not generally known, and may depend on several factors. It is posited that, for systems with no trace constituents that alter the surface chemistry, R{sub f} can be estimated from the bulk far-from-equilibrium dissolution rate of calcite (R{sub b} or k{sub b}), since at equilibrium R{sub f} = R{sub b}, and R{sub p} = 0. Hence it can be inferred that R{sub f} {approx} R{sub p} + R{sub b}. The dissolution rate of pure calcite is measureable and is known to be a function of temperature and pH. At given temperature and pH, equilibrium precipitation is approached when R{sub p} (= R{sub f} - R{sub b}) << R{sub b}. For precipitation rates high enough that R{sub p} >> R{sub b}, both isotopic and trace element partitioning are controlled by the kinetics of ion attachment to the mineral surface, which tend to favor more rapid incorporation of the light isotopes of Ca and discriminate weakly between trace metals and Ca. With varying precipitation rate, a transition region between equilibrium and kinetic control occurs near R{sub p} {approx} R{sub b} for Ca isotopic fractionation. According to this model, Ca isotopic data can be used to estimate R{sub f} for calcite precipitation. Mechanistic models for calcite precipitation indicate that the molecular exchange rate is not constant at constant T and pH, but rather is dependent also on solution saturation state and hence R{sub p}. Allowing R{sub b} to vary as R{sub p}{sup 1/2}, consistent with available precipitation rate studies, produces a better fit to some trace element and isotopic data than a model where R{sub b} is constant. This model can account for most of the experimental data in the literature on the dependence of {sup 44}Ca/{sup 40}Ca and metal/Ca fractionation in calcite as a function of precipitation rate and temperature, and also accounts for {sup 18}O/{sup 16}O variations with some assumptions. The apparent temperature dependence of Ca isotope fractionation in calcite may stem from the dependence of R{sub b} on temperature; there should be analogous pH dependence at pH < 6. The proposed model may be valuable for predicting the behavior of isotopic and trace element fractionation for a range of elements of interest in low-temperature aqueous geochemistry. The theory presented is based on measureable thermo-kinetic parameters in contrast to models that equire hyper-fast diffusivity in near-surface layers of the solid.

  1. Surface kinetic model for isotopic and trace element fractionation during precipitation of calcite from aqueous solution

    SciTech Connect

    DePaolo, Donald J.

    2011-01-01

    A surface reaction kinetic model is developed for predicting Ca isotope fractionation and metal/Ca ratios of calcite as a function of rate of precipitation from aqueous solution. The model is based on the requirements for dynamic equilibrium; i.e. proximity to equilibrium conditions is determined by the ratio of the net precipitation rate (Rp) to the gross forward precipitation rate (Rf), for conditions where ionic transport to the growing crystal surface is not rate-limiting. The value of Rp has been experimentally measured under varying conditions, but the magnitude of Rf is not generally known, and may depend on several factors. It is posited that, for systems with no trace constituents that alter the surface chemistry, Rf can be estimated from the bulk far-from-equilibrium dissolution rate of calcite (Rb or kb), since at equilibrium Rf = Rb, and Rp = 0. Hence it can be inferred that Rf ? Rp + Rb. The dissolution rate of pure calcite is measureable and is known to be a function of temperature and pH. At given temperature and pH, equilibrium precipitation is approached when Rp (=Rf - Rb) « Rb. For precipitation rates high enough that Rp » Rb, both isotopic and trace element partitioning are controlled by the kinetics of ion attachment to the mineral surface, which tend to favor more rapid incorporation of the light isotopes of Ca and discriminate weakly between trace metals and Ca. With varying precipitation rate, a transition region between equilibrium and kinetic control occurs near Rp ? Rb for Ca isotopic fractionation. According to this model, Ca isotopic data can be used to estimate Rf for calcite precipitation. Mechanistic models for calcite precipitation indicate that the molecular exchange rate is not constant at constant T and pH, but rather is dependent also on solution saturation state and hence Rp. Allowing Rb to vary as Rp1/2, consistent with available precipitation rate studies, produces a better fit to some trace element and isotopic data than a model where Rb is constant. This model can account for most of the experimental data in the literature on the dependence of 44Ca/40Ca and metal/Ca fractionation in calcite as a function of precipitation rate and temperature, and also accounts for 18O/16O variations with some assumptions. The apparent temperature dependence of Ca isotope fractionation in calcite may stem from the dependence of Rb on temperature; there should be analogous pH dependence at pH < 6. The proposed model may be valuable for predicting the behavior of isotopic and trace element fractionation for a range of elements of interest in low-temperature aqueous geochemistry. The theory presented is based on measureable thermo-kinetic parameters in contrast to models that require hyper-fast diffusivity in near-surface layers of the solid.

  2. Experimental investigations of trace element fractionation in iron meteorites. II - The influence of sulfur

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Drake, M. J.

    1983-01-01

    The partitioning of Ir, Ge, Ga, W, Cr, Au, P, and Ni between solid metal and metallic liquid is investigated as a function of temperature and the S-concentration of the metallic liquid. The partition coefficients for siderophile elements, such as Ir, W, Ga, and Ge, are found to increase by factors of 10-100 as the S-concentration of the metallic liquid increases from 0-30 wt percent. Partition coefficients for other siderophile elements, such as Ni, Au, and P, increase by factors of only 2-3. In contrast, a decrease is seen in the partition coefficients for the more chalcophile element Cr. These experimentally determined coefficients are used in conjunction with a fractional crystallization model to reproduce the geochemical behavior of Ni, P, Au, and Ir during the magmatic evolution of groups IIAB, IIIAB, IVA and IVB iron meteorites. The mean S-concentration for each group increases in the order IVB, IVA, IIIAB, IIAB, which is in accordance with cosmochemical prediction. However, the geochemical behavior of Ge, Ga, W, and Cr cannot be reproduced in an internally consistent way. It is concluded that the magmatic histories of these iron meteorite groups are more complex than has been generally assumed.

  3. Coronal sources, elemental fractionation, and release mechanisms of heavy ion dropouts in the solar wind

    NASA Astrophysics Data System (ADS)

    Weberg, M. J.; Lepri, S. T.; Zurbuchen, T.

    2013-12-01

    The elemental abundances of heavy ions (m > He) in the solar wind provide information concerning physical processes occurring in the corona. Additionally, the charge state distributions of these heavy ions are sensitive to the temperature profiles of their respective source regions in the corona. Both the abundances and charge states become set within a few solar radii and propagate unchanged throughout the heliosphere, regardless of turbulence, propagation effects, and local heating. Therefore, heavy ions yield in-situ evidence of an environment inaccessible to spacecraft and traditionally only observed via spectroscopy. Heavy ion dropouts are a relatively new class of solar wind events. Their origins lie in large, closed coronal loops where processes such as gravitational settling dominate and can cause a mass-dependent fractionation pattern. In this study we consider and attempt to answer three fundamental questions concerning heavy ion dropouts: (1) Where are the source loops located in the large scale corona?, (2) How does the interplay between coronal processes influence the end elemental abundances?, and (3) What are the most probable release mechanisms?. We begin by analyzing the temporal and spatial variability of heavy ion dropouts and their correlation with heliospheric plasma and magnetic structures. Next we investigate the ordering of the elements inside dropouts with respect to mass, charge state, and First Ionization Potential. Finally, we consider the prevailing solar wind theories and the processes they posit that may be responsible for the release of coronal plasma into interplanetary space.

  4. Numerical Analysis of an H1-Galerkin Mixed Finite Element Method for Time Fractional Telegraph Equation

    PubMed Central

    Wang, Jinfeng; Zhao, Meng; Zhang, Min; Liu, Yang; Li, Hong

    2014-01-01

    We discuss and analyze an H1-Galerkin mixed finite element (H1-GMFE) method to look for the numerical solution of time fractional telegraph equation. We introduce an auxiliary variable to reduce the original equation into lower-order coupled equations and then formulate an H1-GMFE scheme with two important variables. We discretize the Caputo time fractional derivatives using the finite difference methods and approximate the spatial direction by applying the H1-GMFE method. Based on the discussion on the theoretical error analysis in L2-norm for the scalar unknown and its gradient in one dimensional case, we obtain the optimal order of convergence in space-time direction. Further, we also derive the optimal error results for the scalar unknown in H1-norm. Moreover, we derive and analyze the stability of H1-GMFE scheme and give the results of a priori error estimates in two- or three-dimensional cases. In order to verify our theoretical analysis, we give some results of numerical calculation by using the Matlab procedure. PMID:25184148

  5. Separation of tervalent transplutonium and rare-earth elements using for-tveks

    SciTech Connect

    Zaitsev, B.N.; Korolev, V.A.; Korovin, Y.F.; Kuzovov, Y.I.; Kvasnitskii, I.B.; Popik, V.P.

    1986-03-01

    The authors study the distribution of curium, americium, and certain rare-earth elements (REE) between aqueous nitric acid solutions and FOR-tveks under static and dynamic conditions. It is shown that on introducing diethylenetriaminepentaacetic acid into the aqueous solution separation coefficients for the transplutonium elements and REE can be obtained which are sufficiently high for practical use. A method is proposed for the group separation of REE and transplutonium elements under dynamic conditions. On a column 22 cm high coefficients of approximately 500 are obtained for the purification of curium from cerium, more than 260 from neodymium, 250 from lanthanum, and 14 from europium and gadolinium. The possibility has been studied of separating palladium from transplutonium elements and REE and isolating it as an individual product.

  6. The effect of rare earth elements on the texture and formability of asymmetrically rolled magnesium sheet

    SciTech Connect

    Alderman, Dr. Martyn; Cavin, Odis Burl; Davis, Dr. Bruce; Muralidharan, Govindarajan; Muth, Thomas R; Peter, William H; Randman, David; Watkins, Thomas R

    2011-01-01

    The lack of formability is a serious issue when considering magnesium alloys for various applications. Standard symmetric rolling introduces a strong basal texture that decreases the formability; however, asymmetric rolling has been put forward as a possible route to produce sheet with weaker texture and greater ductility. It has also been shown in recent work that weaker textures can be produced through the addition of rare earth elements to magnesium alloys. Therefore, this study has been carried out to investigate the effect of rare earth additions on the texture changes during asymmetric rolling. Two alloys have been used, AZ31B and ZEK100. The effect that the rare earth additions have on the texture of asymmetrically rolled sheet and the subsequent changes in formability will be discussed.

  7. Accurate projected augmented wave (PAW) datasets for rare-earth elements (RE=La-Lu)

    NASA Astrophysics Data System (ADS)

    Topsakal, Mehmet; Wentzcovitch, Renata

    2015-03-01

    We provide accurate projected augmented wave (PAW) datasets for rare-earth (RE) elements with some suggested Hubbard U values allowing efficient plane-wave calculations. Solid state tests of generated datasets were performed on rare-earth nitrides. Through density of state (DOS) and equation of state (EoS) comparisons, generated datasets were shown to yield excellent results comparable to highly accurate all-electron full-potential linearized augmented plane-wave plus local orbital (FLAPW+LO) calculations. Hubbard U values for trivalent RE ions are determined according to hybrid functional calculations. We believe that these new and open-source PAW datasets will allow further studies on rare-earth materials. NSF/EAR 1319361

  8. Extraction of rare-earth elements from nitric solutions by phosphoryl-containing podands

    SciTech Connect

    Turanov, A.N.; Karandashev, V.K.; Baulin, V.E.

    1999-11-01

    The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO{sub 3} solutions by phosphoryl-containing podands of various structures has been studied.. It has been found that the maximum extraction of rare earth elements is exhibited by reagents containing one ether oxygen atom in the molecule, bound to diphenylphosphoryl or ditolylphosphoryl groups by methylene and o-phenylene fragments. The structure of these reagents is best suited for the polydentate coordination of the ligand and the conditions of a chelate complex formation. The effect of HNO{sub 3} concentration in the aqueous phase and that of the nature of an organic diluent on the extraction of rare earth elements and Y are considered. Stoichiometric of the extracted complexes has been determined and the extraction constants calculated.

  9. Symmetric charge-transfer cross sections of IIIa rare-earth-metal elements

    SciTech Connect

    Hashida, Masaki; Sakabe, Shuji; Izawa, Yasukazu

    2011-03-15

    Symmetric charge-transfer cross sections of IIIa rare-earth-metal elements (Sc, Y, and Gd) in the impact energy range of 30 to 1000 eV were measured for the first time. The experiments were performed with a crossed-beam apparatus that featured primary ion production by photoionization with a tunable dye laser. Comparing the cross sections of IIIa rare-earth-metal elements ({sigma}{sub Sc}, {sigma}{sub Y}, and {sigma}{sub Gd}) with those of alkali metals or helium {sigma}{sub 0}, we found that {sigma}{sub 0{approx_equal}{sigma}Sc}<{sigma}{sub Y}<{sigma}{sub Gd{approx_equal}}2{sigma}{sub 0}at an impact energy of 1000 eV.

  10. Geochemical behaviour of trace elements during fractional crystallization and crustal assimilation of the felsic alkaline magmas of the state of Rio de Janeiro, Brazil.

    PubMed

    Motoki, Akihisa; Sichel, Susanna E; Vargas, Thais; Melo, Dean P; Motoki, Kenji F

    2015-12-01

    This paper presents geochemical behaviour of trace elements of the felsic alkaline rocks of the state of Rio de Janeiro, Brazil, with special attention of fractional crystallization and continental crust assimilation. Fractionation of leucite and K-feldspar increases Rb/K and decreases K2O/(K2O+Na2O). Primitive nepheline syenite magmas have low Zr/TiO2, Sr, and Ba. On the Nb/Y vs. Zr/TiO2 diagram, these rocks are projected on the field of alkaline basalt, basanite, and nephelinite, instead of phonolite. Well-fractionated peralkaline nepheline syenite has high Zr/TiO2 but there are no zircon. The diagrams of silica saturation index (SSI) distinguish the trends originated form fractional crystallization and crustal assimilation. In the field of SSI<-200, Zr/TiO2 and Ba/Sr have negative correlations to SSI in consequence of fractional crystallization. In the field of SSI>-200, they show positive correlations due to continental crust assimilation. Total REEs (Rare Earth Elements) is nearly 10 times that of granitic rocks, but LaN/SmN and LaN/YbN are similar. REE trend is linear and Eu anomaly is irrelevant. The pegmatitic liquid generated by country rock partial melting is SiO2-oversaturated and peraluminous with high Ba, Sr, Ba/Sr, Zr/TiO2, and SSI, with high content of fluids. This model justifies the peraluminous and SiO2-oversaturated composition of the rocks with relevant effects of continental crust assimilation. PMID:26628026

  11. Transport of rare earth element-tagged soil particles in response to thunderstorm runoff.

    PubMed

    Matisoff, G; Ketterer, M E; Wilson, C G; Layman, R; Whiting, P J

    2001-08-15

    The downslope transport of rare earth element-tagged soil particles remobilized during a spring thunderstorm was studied on both a natural prairie and an agricultural field in southwestern Iowa (U.S.A.). A technique was developed for tagging natural soils with the rare earth elements Eu, Tb, and Ho to approximately 1,000 ppm via coprecipitation with MnO2. Tagged material was replaced in target locations; surficial soil samples were collected following precipitation and runoff; and rare earth element concentrations were determined by inductively coupled plasma mass spectrometry. Diffusion and exponential models were applied to the concentration-distance data to determine particle transport distances. The results indicate that the concentration-distance data are well described by the diffusion model, butthe exponential model does not simulate the rapid drop-off in concentrations near the tagged source. Using the diffusion model, calculated particle transport distances at all hillside locations and at both the cultivated and natural prairie sites were short, ranging from 3 to 73 cm during this single runoff event. This study successfully demonstrates a new tool for studying soil erosion. PMID:11529577

  12. Bacterial Disproportionation of Elemental Sulfur Inferred from a Field Study of Stable-Isotope Fractionations between Elemental Sulfur and Pyrite

    NASA Astrophysics Data System (ADS)

    Hardisty, D.; Pratt, L. M.; Olyphant, G. A.; Bell, J.; Johnson, A.

    2011-12-01

    Elemental sulfur (ES) is a common product of pyrite oxidation during acid mine drainage (AMD), but bacterial disproportionation of ES has not previously been inferred in acidic environments. Pore water profiles were collected seasonally within a coal-mine waste deposit, Minnehaha, in Southwest Indiana that has been abandoned for over 30 years. Geochemical characterization and modeling were used to assess how the interactions between the sulfur and iron cycle are affected by seasonally dynamic hydrologic conditions. Pore waters were collected seasonally and concentrations of Fe-species and sulfur isotopic compositions of sulfate were determined. Additionally, a sediment core was collected and used for sequential extraction and isotopic characterization of solid-phase sulfur species including elemental sulfur (?34Ses), pyrite (?34Spy), acid-volatile sulfides, water-soluble sulfates, and acid-soluble sulfates. The dominant disulfide phase was found to be pyrite through x-ray diffraction of an additional sediment core. Sulfur isotope fractionations between ?34Spy and ?34Ses (?34Ses-py) of up to -33% are inferred to indicate bacterial disproportionation of ES in the presence of a non-limiting sulfide 'scrub' Fe(III). The initial isotopic composition, following formation from pyrite oxidation, is inferred from ?34Spy, found to be ? 8.75% at the study site. Although ES has previously been found to accumulate in acidic Fe(III)-rich pore waters, ES is typically assumed to account for less than 1% of the oxidized sulfur pool and measurements of the ES isotopic composition are often neglected during field studies of acid AMD. The pore waters at Minnehaha were seasonally suboxic with sharp transitions from Fe(III)- to Fe(II)- dominated conditions near the phreatic surface. It is hypothesized that the sulfide product of ES disproportionation, fractionated by up to -8.6%, is immediately re-oxidized to ES near the redox gradient via reaction with Fe(III). Sulfide re-oxidation allows for the accumulation of isotopically light ES that can then become subject to further sulfur disproportionation. A mass-balance model for ES, incorporating seasonally varying rates for pyrite oxidation, ES disproportionation, and ES oxidation, was developed in order to determine the potential and conditions necessary for extensive recycling of ES by disproportionating bacteria to produce ES enriched in 32S compared to the pyrite source. Simulations run for 32 seasonal cycles resulted in a ?34Ses-py of -16.4.% and an ES concentration of 170 ppm, which is consistent with average values obtained from the sediment core. The findings suggest that ES disproportionation is likely an important microbial process in AMD that should be considered at similar mining waste deposits experiencing seasonally varying hydrologic conditions and that ?34Ses-py can be used to estimate multiple cycles of ES disproportionation in oxic settings where the original source of ES is pyrite oxidation.

  13. Origin of fluorite mineralizations in the Nuba Mountains, Sudan and their rare earth element geochemistry

    NASA Astrophysics Data System (ADS)

    Ismail, Ibrahim; Baioumy, Hassan; Ouyang, Hegen; Mossa, Hesham; Aly, Hisham Fouad

    2015-12-01

    Among other mineralizations in the basement complex of the Nuba Mountains, fluorite occurs as lenses and veins in a number of localities. The rare earth elements (REE) geochemistry in these fluorites along with their petrography and fluid inclusion was investigated in this study to discuss the origin the fluorites and shed the light on the economic importance of the REE. Fluorites in the Nuba Mountains are classified into four categories based on their petrography. Category I (F1) is characterized by pink color and free of inclusions. Category II (F2) is zoned of alternating pink and colorless zones with euhedral outline or anhedral patchy pink and colorless fluorite enclosing category I fluorite and is usually sieved with submicroscopic silicate minerals. Category III (F3) is colorless, euhedral to anhedral fluorite and associated with quartz and/or orthoclase. Category IV (F4) is colorless, either massive or dispersed, corroded grains associated with calcite and pertain to the late introduced carbonatites in Dumbeir area. Gangue minerals in the studied fluorites include quartz, calcite, orthoclase and muscovite. The ?REE ranges between 541 and 10,430 ppm with an average of 3234 ppm. Chondrite-normalized REE patterns for fluorite from different localities exhibit LREE enrichment relative to HREE as shown by (La/Yb)N ratios that vary from 16 to 194 and significant positive Eu anomalies that are pronounced with Eu/Eu* from 1.1 to 2.5. The Tb/La and Tb/Ca ratios of fluorites in the present study indicate that they plot mainly in the pegmatitic or high-hydrothermal field with the characteristics of primary crystallization and remobilization trend. The clear heterogeneity of fluorite, abundance of growth zones, irregular shapes of grains, presence of fluorite inclusions in other minerals as well as the relatively high concentration of REE in the studied fluorites are supportive for this interpretation. The relatively high Tb/La (0.002-0.013) and low Tb/Ca (0.0000007-0.0000086) ratios of the studied fluorites suggest that they precipitated from fractionated ore-bearing fluids at a late stage of deposition. The microtherometric measurements of the primary inclusions show that the Nuba Mountains fluorites were formed at temperatures greater than 600 °C. These values along with the low salinity of the fluid inclusions indicates homogenize at moderate temperatures. Thus the studied fluorite probably formed during the late stages of pegmatite consolidation under magmatic-hydrothermal transition conditions supporting the previous conclusions from REE geochemistry.

  14. What Can Neutrinos Tell Us about Light Elements in Earth's Core?

    NASA Astrophysics Data System (ADS)

    Li, J.; Dye, S.; Enomoto, S.

    2014-12-01

    The light element composition of the Earth's core remains mysterious despite decades' of research. Without any direct samples, our knowledge of the core composition has relied on a diversity of constraints including the density and velocity profiles derived from seismic and geophysical observations, the composition models proposed on the basis of geochemical and cosmochemical measurements, the material properties determined by mineral physics investigations, and the thermal and dynamo requirements coming out of dynamic modeling. The leading candidates for the principal light element include hydrogen, carbon, oxygen, sulfur and silicon, in the order of increasing atomic number. While each candidate stands out in some aspects and raises questions in others, none has been universally accepted as the dominant light element in the core. The controversy arises partly because the properties and behavior of various iron-alloys at extreme pressure and temperature conditions have not been fully constrained. It is also conceivable that existing approaches will not produce unique solution, and therefore requires new strategies. Neutrino oscillation tomography has recently emerged as a promising technique to probe the composition of Earth's interior. Neutrinos are produced in the atmosphere by cosmic ray interactions. Atmospheric neutrinos pass through the Earth's mantle and core, with flavor oscillations being affected by the electron density of the medium along the trajectories. The unique sensitivity of the atmospheric neutrinos to electron density introduces a contrast between hydrogen, which has a higher electron density, and carbon, oxygen, sulfur, and silicon, which have lower and similar electron densities. With sufficient exposure to an appropriate energy range, atmospheric neutrino measurements may allow us to detect the presence of the core and measure its radius. Here we compare electron densities of candidate model compositions of Earth's core and estimate the exposure requirements for identifying the dominant light element thorough neutrino oscillation tomography for both neutrino mass hierarchies. In particular, we will evaluate if any of the on-going and next-generation projects IceCube, PINGU, MICA, and HyperK can tell us about the light elements in Earth's core.

  15. Determination of rare earth elements in environmental materials by inductively coupled plasma mass spectrometry

    SciTech Connect

    Panday, V.K.; Hoppstock, K.; Becker, J.S.; Dietze, H.J.

    1996-09-01

    Despite the fact that rare earth elements (REE) have found increasing use in modern technology only few data are available on their concentrations in biological and environmental samples. Inductively coupled plasma mass spectrometry (ICP-MS) has been employed to study the concentration of rare earth elements (REE) in various environmental materials (e.g., pine needles, mussel tissue, apple leaves) available from National Institute of Standards and Technology (NIST), the Bureau of European Communities (BCR), and the German Environmental Specimens Bank. After the decomposition of the environmental samples with HNO{sub 3}, the REE (present mostly in the ng/g-range) were separated from the matrix and simultaneously preconcentrated using liquid-liquid extraction with bis(2-ethyl hexyl)-ortho-phosphoric acid (HDEHP) in toluene as a selective reagent at pH = 2 and subsequent back extraction of the elements into the aqueous by 6M HNO{sub 3}. Recoveries of better 90% were obtained for almost all REE. A Perkin Elmer/Sciex ELAN 5000 ICP-MS and HR-ICP-MS ELEMENT from Finnigan MAT were used for quantitative analysis (by external calibration and ID-ICP-MS) of REE. The results of determination of REE concentrations agree well with the data available on some of these materials. Further supplement information on the contents of various REE in these materials.

  16. Iridium, sulfur isotopes and rare earth elements in the Cretaceous-Tertiary boundary clay at Stevns Klint, Denmark

    SciTech Connect

    Schmitz, B.; Andersson, P.; Dahl, J.

    1988-01-01

    Microbial activity and redox-controlled precipitation have been of major importance in the process of metal accumulation in the strongly Ir-enriched Cretaceous-Tertiary (K-T) boundary clay, the Fish Clay, at Stevns Klint in Denmark. Two important findings support this view: (1) Kerogen, recovered by leaching the Fish Clay in HCl and HF, shows an Ir concentration of 1100 ppb; this represents about 50% of the Ir present in the bulk sample Fish clay. Strong organometallic complexes is the most probable carrier phase for this fraction of Ir. Kerogen separated from the K-T boundary clay at Caravaca, Spain, similarly exhibits enhanced Ir concentrations. (2) Sulfur isotope analyses of metal-rich pyrite spherules, which occur in extreme abundance (about 10% by weight) in the basal Fish Clay, give a delta/sup 34/S value of -32 per thousand. This very low value shows that sulfide formation by anaerobic bacteria was intensive in the Fish Clay during early diagenesis. Since the pyrite spherules are major carriers of elements such as Ni, Co, As, Sb and Zn, microbial activity may have played an important role for concentrating these elements. In the Fish Clay large amounts of rare earth elements have precipitated from sea water on fish scales. Analyses reveal that, compared with sea water, the Fish Clay is only about four times less enriched in sea-water derived lanthanides than in Ir. This shows that a sea-water origin is plausible for elements that are strongly enriched in the clay, but whose origin cannot be accounted for by a lithogenic precursor.

  17. Iridium, sulfur isotopes and rare earth elements in the Cretaceous-Tertiary boundary clay at Stevns Klint, Denmark

    NASA Astrophysics Data System (ADS)

    Schmitz, Birger; Andersson, Per; Dahl, Jeremy

    1988-01-01

    Microbial activity and redox-controlled precipitation have been of major importance in the process of metal accumulation in the strongly Ir-enriched Cretaceous-Tertiary (K-T) boundary clay, the Fish Clay, at Stevns Klint in Denmark. Two important findings support this view: 1) Kerogen, recovered by leaching the Fish Clay in HCl and HF, shows an Ir concentration of 1100 ppb; this represents about 50% of the Ir present in the bulk sample Fish Clay. Strong organometallic complexes is the most probable carrier phase for this fraction of Ir. Kerogen separated from the K-T boundary clay at Caravaca, Spain, similarly exhibits enhanced Ir concentrations. 2) Sulfur isotope analyses of metal-rich pyrite spherules, which occur in extreme abundance (about 10% by weight) in the basal Fish Clay, give a ? 34S value of -32%.. This very low value shows that sulfide formation by anaerobic bacteria was intensive in the Fish Clay during early diagenesis. Since the pyrite spherules are major carriers of elements such as Ni, Co, As, Sb and Zn, microbial activity may have played an important role for concentrating these elements. In the Fish Clay large amounts of rare earth elements have precipitated from sea water on fish scales. Analyses reveal that, compared with sea water, the Fish Clay is only about four times less enriched in sea-water derived lanthanides than in Ir. This shows that a sea-water origin is plausible for elements that are strongly enriched in the clay, but whose origin cannot be accounted for by a lithogenic precursor.

  18. Complementary rare earth element patterns in unique achondrites, such as ALHA 77005 and shergottites, and in the earth

    NASA Technical Reports Server (NTRS)

    Ma, M.-S.; Schmitt, R. A.; Laul, J. C.

    1982-01-01

    Abundances of major, minor, and trace elements are determined in the Antarctic achondrite Allan Hills (ALHA) 77005 via sequential instrumental and radiochemical neutron activation analysis. The rare earth element (REE) abundances of ALHA 77005 reveal a unique chondritic normalized pattern; that is, the REEs are nearly unfractionated from La to Pr at approximately 1.0X chondrites, monotonically increased from Pr to Gd at approximately 3.4X with no Eu anomaly, nearly unfractionated from Gd and Ho and monotonically decreased from Ho to Lu at approximately 2.2X. It is noted that this unique REE pattern of ALHA 77005 can be modeled by a melting process involving a continuous melting and progressive partial removal of melt from a light REE enriched source material. In a model of this type, ALHA 77005 could represent either a crystallized cumulate from such a melt or the residual source material. Calculations show that the parent liquids for the shergottites could also be derived from a light REE enriched source material similar to that for ALHA 77005.

  19. Toward understanding early Earth evolution: Prescription for approach from terrestrial noble gas and light element records in lunar soils

    PubMed Central

    Ozima, Minoru; Yin, Qing-Zhu; Podosek, Frank A.; Miura, Yayoi N.

    2008-01-01

    Because of the almost total lack of geological record on the Earth's surface before 4 billion years ago, the history of the Earth during this period is still enigmatic. Here we describe a practical approach to tackle the formidable problems caused by this lack. We propose that examinations of lunar soils for light elements such as He, N, O, Ne, and Ar would shed a new light on this dark age in the Earth's history and resolve three of the most fundamental questions in earth science: the onset time of the geomagnetic field, the appearance of an oxygen atmosphere, and the secular variation of an Earth–Moon dynamical system. PMID:19001263

  20. Bioleaching of rare earth and radioactive elements from red mud using Penicillium tricolor RM-10.

    PubMed

    Qu, Yang; Lian, Bin

    2013-05-01

    The aim of this work is to investigate biological leaching of rare earth elements (REEs) and radioactive elements from red mud, and to evaluate the radioactivity of the bioleached red mud used for construction materials. A filamentous, acid-producing fungi named RM-10, identified as Penicillium tricolor, is isolated from red mud. In our bioleaching experiments by using RM-10, a total concentration of 2% (w/v) red mud under one-step bioleaching process was generally found to give the maximum leaching ratios of the REEs and radioactive elements. However, the highest extraction yields are achieved under two-step bioleaching process at 10% (w/v) pulp density. At pulp densities of 2% and 5% (w/v), red mud processed under both one- and two-step bioleaching can meet the radioactivity regulations in China. PMID:23548400

  1. Experimental partitioning of rare earth elements and scandium among armalcolite, ilmenite, olivine and mare basalt liquid

    NASA Technical Reports Server (NTRS)

    Irving, A. J.; Merrill, R. B.; Singleton, D. E.

    1978-01-01

    An experimental study was carried out to measure partition coefficients for two rare-earth elements (Sm and Tm) and Sc among armalcolite, ilmenite, olivine and liquid coexisting in a system modeled on high-Ti mare basalt 74275. This 'primitive' sample was chosen for study because its major and trace element chemistry as well as its equilibrium phase relations at atmospheric pressure are known from previous studies. Beta-track analytical techniques were used so that partition coefficients could be measured in an environment whose bulk trace element composition is similar to that of the natural basalt. Partition coefficients for Cr and Mn were determined in the same experiments by microprobe analysis. The only equilibrium partial melting model appears to be one in which ilmenite is initially present in the source region but is consumed by melting before segregation of the high-Ti mare basalt liquid from the residue.

  2. Quantification of rare earth elements using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Martin, Madhavi; Martin, Rodger C.; Allman, Steve; Brice, Deanne; Wymore, Ann; Andre, Nicolas

    2015-12-01

    A study of the optical emission as a function of concentration of laser-ablated yttrium (Y) and of six rare earth elements, europium (Eu), gadolinium (Gd), lanthanum (La), praseodymium (Pr), neodymium (Nd), and samarium (Sm), has been evaluated using the laser-induced breakdown spectroscopy (LIBS) technique. Statistical methodology using multivariate analysis has been used to obtain the sampling errors, coefficient of regression, calibration, and cross-validation of measurements as they relate to the LIBS analysis in graphite-matrix pellets that were doped with elements at several concentrations. Each element (in oxide form) was mixed in the graphite matrix in percentages ranging from 1% to 50% by weight and the LIBS spectra obtained for each composition as well as for pure oxide samples. Finally, a single pellet was mixed with all the elements in equal oxide masses to determine if we can identify the elemental peaks in a mixed pellet. This dataset is relevant for future application to studies of fission product content and distribution in irradiated nuclear fuels. These results demonstrate that LIBS technique is inherently well suited for the future challenge of in situ analysis of nuclear materials. These studies also show that LIBS spectral analysis using statistical methodology can provide quantitative results and suggest an approach in future to the far more challenging multielemental analysis of ~ 20 primary elements in high-burnup nuclear reactor fuel.

  3. Rare earth elements recycling from waste phosphor by dual hydrochloric acid dissolution.

    PubMed

    Liu, Hu; Zhang, Shengen; Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin; Volinsky, Alex A

    2014-05-15

    This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y0.95Eu0.05)2O3 in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce0.67Tb0.33MgAl11O19) and the Blue phosphor (Ba0.9Eu0.1MgAl10O17) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications. PMID:24681591

  4. Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

    SciTech Connect

    Madhavi Z. Martin; Robert V. Fox; Andrzej W. Miziolek; Frank C. DeLucia, Jr.; Nicolas Andre

    2001-05-01

    There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.

  5. Spectral analysis of rare earth elements using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Martin, Madhavi Z.; Fox, Robert V.; Miziolek, Andrzej W.; DeLucia, Frank C.; André, Nicolas

    2015-06-01

    There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.

  6. New Rare Earth Element Abundance Distributions for the Sun and Five r-Process-Rich Very Metal-Poor Stars

    E-print Network

    Sneden, Christopher; Cowan, John J; Ivans, Inese I; Hartog, Elizabeth A Den

    2009-01-01

    We have derived new abundances of the rare-earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally-consistent Ba, rare-earth, and Hf (56<= Z <= 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.

  7. NEW RARE EARTH ELEMENT ABUNDANCE DISTRIBUTIONS FOR THE SUN AND FIVE r-PROCESS-RICH VERY METAL-POOR STARS

    SciTech Connect

    Sneden, Christopher; Lawler, James E.; Den Hartog, Elizabeth A.; Cowan, John J.; Ivans, Inese I. E-mail: jelawler@wisc.edu E-mail: cowan@nhn.ou.edu

    2009-05-15

    We have derived new abundances of the rare earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low-metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally consistent Ba, rare earth, and Hf (56 {<=} Z {<=} 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.

  8. Investigation of biological activity of fine fraction of lunar surface material returned to earth by the Luna 16 automatic station

    NASA Technical Reports Server (NTRS)

    Kustov, V. V.; Ostapenko, O. F.; Petrukhin, V. G.

    1974-01-01

    The biological action of a sample of lunar surface material returned to earth by the Luna 16 automatic station from a new region of the mare surface on male white mice was studied. The condition and behavior of the animals were observed; the intensity of their oxygen consumption was recorded, and motor activity of the muscles, leucocyte and erythrocytes counts in the peripheral blood, and the activity of whole blood chloinesterase were determined. Experimental results showed that the tested doses of the fine fraction of the lunar surface material from the Sea of Fertility were virtually innocuous for white mice.

  9. Origin of Volatiles in Earth: Indigenous Versus Exogenous Sources Based on Highly Siderophile, Volatile Siderophile, and Light Volatile Elements

    NASA Technical Reports Server (NTRS)

    Righter, K.; Danielson, L.; Pando, K. M.; Marin, N.; Nickodem, K.

    2015-01-01

    Origin of Earth's volatiles has traditionally been ascribed to late accretion of material after major differentiation events - chondrites, comets, ice or other exogenous sources. A competing theory is that the Earth accreted its volatiles as it was built, thus water and other building blocks were present early and during differentiation and core formation (indigenous). Here we discuss geochemical evidence from three groups of elements that suggests Earth's volatiles were acquired during accretion and did not require additional sources after differentiation.

  10. Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility

    E-print Network

    Zheng, Yufeng

    Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas

  11. The chemistry of the light rare-earth elements as determined by electron energy loss spectroscopy

    SciTech Connect

    Fortner, J.A.; Buck, E.C.

    1996-06-01

    The energy loss spectra of the rare earths are characterized by sharp {ital M}{sub 4,5} edges, the relative intensities of which are characteristic of the 4{ital f}-shell occupancy of the excited ion. For the light rare earths, the dependence of these relative peak heights on 4{ital f}-shell occupancy is quite pronounced. Thus they may be used to determine the oxidation state of the multivalent elements Ce and Pr. The second derivative of the spectrum is shown to be extremely sensitive to the chemical environment. Modern instrumentation and detection techniques allow the oxidation state of Ce and Pr to be determined even when they are present as only minor constituents. {copyright} {ital 1996 American Institute of Physics.}

  12. The Koshak section: Evidence for element fractionation and an oxidation event at the K/T boundary

    NASA Technical Reports Server (NTRS)

    Nazarov, M. A.; Badjukov, D. D.; Barsukova, L. D.; Kolesov, G. M.; Naidin, D. P.

    1993-01-01

    The Koshak site is a new K/T section located about 125 km EEN of the Fort Shevchenko city, Mangyshlak, Kazakhstan. In this paper, we report results of geochemical and mineralogical studies of this section which indicate a deep element fractionation and an oxidation event at the K/T boundary.

  13. Elemental composition and functional groups in soil labile organic matter fractions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Labile organic matter fractions are major components involved in nutrient cycle in soil. In this chapter, we examine three labile organic matter fraction: light fraction (LF), humic acid (HA) and fulvic acid (HA) in Alabama cotton soils (ultisol) amended with chemical fertilizer (NH4NO3) and poult...

  14. On the origin of falling-tone chorus elements in Earth's inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Breuillard, H.; Agapitov, O.; Artemyev, A.; Krasnoselskikh, V.; Le Contel, O.; Cully, C. M.; Angelopoulos, V.; Zaliznyak, Y.; Rolland, G.

    2014-12-01

    Generation of extremely/very low frequency (ELF/VLF) chorus waves in Earth's inner magnetosphere has received increased attention recently because of their significance for radiation belt dynamics. Though past theoretical and numerical models have demonstrated how rising-tone chorus elements are produced, falling-tone chorus element generation has yet to be explained. Our new model proposes that weak-amplitude falling-tone chorus elements can be generated by magnetospheric reflection of rising-tone elements. Using ray tracing in a realistic plasma model of the inner magnetosphere, we demonstrate that rising-tone elements originating at the magnetic equator propagate to higher latitudes. Upon reflection there, they propagate to lower L-shells and turn into oblique falling tones of reduced power, frequency, and bandwidth relative to their progenitor rising tones. Our results are in good agreement with comprehensive statistical studies of such waves, notably using magnetic field measurements from THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft. Thus, we conclude that the proposed mechanism can be responsible for the generation of weak-amplitude falling-tone chorus emissions.

  15. Study on the activated laser welding of ferritic stainless steel with rare earth elements yttrium

    NASA Astrophysics Data System (ADS)

    Wang, Yonghui; Hu, Shengsun; Shen, Junqi

    2015-10-01

    The ferritic stainless steel SUS430 was used in this work. Based on a multi-component activating flux, composed of 50% ZrO2, 12.09 % CaCO3, 10.43 % CaO, and 27.49 % MgO, a series of modified activating fluxes with 0.5%, 1%, 2%, 5%, 10%, 15%, and 20% of rare earth (RE) element yttrium (Y) respectively were produced, and their effects on the weld penetration (WP) and corrosion resistant (CR) property were studied. Results showed that RE element Y hardly had any effects on increasing the WP. In the FeCl3 spot corrosion experiment, the corrosion rates of almost all the samples cut from welded joints turned out to be greater than the parent metal (23.51 g/m2 h). However, there was an exception that the corrosion rate of the sample with 5% Y was only 21.96 g/m2 h, which was even better than parent metal. The further Energy Dispersive Spectrometer (EDS) test showed the existence of elements Zr, Ca, O, and Y in the molten slag near the weld seam while none of them were found in the weld metal, indicating the direct transition of element from activating fluxes to the welding seam did not exist. It was known that certain composition of activating fluxes effectively restrain the loss of Cr element in the process of laser welding, and as a result, the CR of welded joints was improved.

  16. Decrease of concentration and colloidal fraction of organic carbon and trace elements in response to the anomalously hot summer 2010 in a humic boreal lake.

    PubMed

    Shirokova, L S; Pokrovsky, O S; Moreva, O Yu; Chupakov, A V; Zabelina, S A; Klimov, S I; Shorina, N V; Vorobieva, T Ya

    2013-10-01

    The colloidal distribution and size fractionation of organic carbon (OC), major elements and trace elements (TE) were studied in a seasonally stratified, organic-rich boreal lake, Lake Svyatoe, located in the European subarctic zone (NW Russia, Arkhangelsk region). This study took place over the course of 4 years in both winter and summer periods using an in situ dialysis technique (1 kDa, 10 kDa and 50 kDa) and traditional frontal filtration and ultrafiltration (5, 0.22 and 0.025 ?m). We observed a systematic difference in dissolved elements and colloidal fractions between summer and winter periods with the highest proportion of organic and organo-ferric colloids (1 kDa-0.22 ?m) observed during winter periods. The anomalously hot summer of 2010 in European Russia produced surface water temperatures of approximately 30°C, which were 10° above the usual summer temperatures and brought about crucial changes in element speciation and size fractionation. In August 2010, the concentration of dissolved organic carbon (DOC) decreased by more than 30% compared to normal period, while the relative proportion of organic colloids decreased from 70-80% to only 20-30% over the full depth of the water column. Similarly, the proportion of colloidal Fe decreased from 90-98% in most summers and winters to approximately 60-70% in August 2010. During this hot summer, measurable and significant (>30% compared to other periods) decreases in the colloidal fractions of Ca, Mg, Sr, Ba, Al, Ti, Ni, As, V, Co, Y, all rare earth elements (REEs), Zr, Hf, Th and U were also observed. In addition, dissolved (<0.22 ?m) TE concentrations decreased by a factor of 2 to 6 compared to previously investigated periods. The three processes most likely responsible for such a crucial change in element biogeochemistry with elevated water temperature are 1) massive phytoplankton bloom, 2) enhanced mineralization (respiration) of allochthonous dissolved organic matter by heterotrophic aerobic bacterioplankton and 3) photo-degradation of DOM and photo-chemical liberation of organic-bound TE. While the first process may have caused significant decreases in the total dissolved concentration of micronutrients (a factor of 2 to 5 for Cr, Mn, Fe, Ni, Cu, Zn and Cd and a factor of >100 for Co), the second and third factors could have brought about the decrease of allochthonous DOC concentration as well as the concentration and proportion of organic and organo-mineral colloidal forms of non-essential low-soluble trace elements present in the form of organic colloids (Al, Y, Ti, Zr, Hf, Th, Pb, all REEs). It can be hypothesized that climate warming in high latitudes capable of significantly raising surface water temperatures will produce a decrease in the colloidal fraction of most trace elements and, as a result, an increase in the most labile low molecular weight LMW(<1 kDa) fraction. PMID:23792250

  17. Rare earth elements geochemistry in springs from Taftan geothermal area SE Iran

    NASA Astrophysics Data System (ADS)

    Shakeri, Ata; Ghoreyshinia, Sayedkazem; Mehrabi, Behzad; Delavari, Morteza

    2015-10-01

    Concentrations of rare earth elements (REEs) were determined in springs and andesitic-dacitic rocks of Taftan geothermal field. Hydrochemical results of major ions indicate that thermal springs are Na-SO4-Cl and Ca-SO4-Cl types. Concentrations of REEs are in ranges of 10- 4 to 1.2 and 49 to ~ 62 times of chondrite for springwater and rock samples, respectively. The thermal (STS and TTS) and the cold (APS) springs with low pH values exhibit a very high REE contents (0.64 to 3.15 mg/l). Saturation index indicates that Fe and Al phases can control dissolved REE concentration in FTS and PF cold springs. The speciation of REE complexes indicates dominant presence of LnSO4+ and free ion in the Taftan thermal springs. In APS cold spring with pH ~ 4, fluoride complexes are dominate over the free ion and sulfate species, while in PF and FTS cold springs with pH 6.4 and 7, respectively, carbonate complexes (LnCO3+) are predominant species. Chondrite-normalized pattern for the low-pH waters show very distinctive gull-wing patterns, characteristic feature of acid-sulfate geothermal systems, and are similar to those of the host rocks. Chemical characteristics of rare earth elements in spring and volcanic rock samples indicate that REEs are originated from the andesitic-dacitic host rocks. Whole-rock-normalized REE patterns and petrographic evidences show that rare earth elements leached mainly from marginal alteration of minerals and matrix decomposition in volcanic rocks. In chondrite-normalized REE patterns, significant negative Eu anomaly in the cold springs compare to the thermal and acidic springs indicates that alteration of plagioclase is more intense in the later, corresponding to increasing in temperature and acidic state of reactant water.

  18. Contrasting behaviour of anthropogenic gadolinium and natural rare earth elements in estuaries and the gadolinium input into the North Sea

    NASA Astrophysics Data System (ADS)

    Kulaks?z, Serkan; Bau, Michael

    2007-08-01

    All major rivers in northwestern Germany that flow into the North Sea, including the Weser River, display rare earth element (REE) patterns with large positive gadolinium (Gd) anomalies that indicate the presence of anthropogenic Gd derived from contrast agents used in magnetic resonance imaging. This microcontaminant cannot be removed by common sewage treatment technology and enters rivers and lakes with the discharge from waste water treatment plants. As elsewhere, a large fraction of the natural dissolved REE in the Weser River are associated with colloids. These colloids aggregate during mixing of freshwater and seawater in the low-salinity part of the Weser Estuary and the dissolved REE are partially removed from the river water together with the colloids. In marked contrast to the natural REE, the anthropogenic Gd behaves conservatively during this estuarine mixing and transits through the Weser Estuary almost unaffected. This indicates that the speciation of anthropogenic Gd is different from that of natural Gd and suggests a long environmental half-life of the anthropogenic Gd complexes used as contrast agents. The amount of anthropogenic Gd introduced into seawater via rivers is significant and produces anthropogenic positive Gd anomalies in coastal seawater. This is observed in the southwestern North Sea, off the coast of the East Frisian Islands, where anthropogenic Gd is mostly derived from the rivers Rhine and Thames. Its long environmental half-life and conservative estuarine behaviour suggest that anthropogenic Gd might be utilized as a pseudo-natural far-field tracer for truly dissolved riverine REE input into seawater and for discharge from waste water treatment plants and for sewage in river, ground and drinking water. The widespread distribution of anthropogenic Gd is an example of how the increasing use of "exotic" (ultra)trace elements in high-tech processes will in the future significantly hamper studies of the distribution and geochemical behaviour of such elements in natural systems.

  19. New fission fragment distributions and r-process origin of the rare-earth elements

    E-print Network

    S. Goriely; J. -L. Sida; J. -F. Lemaitre; S. Panebianco; N. Dubray; S. Hilaire; A. Bauswein; H. -Thomas Janka

    2013-11-22

    Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process elements with nuclear mass numbers A > 140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular the fission fragment yields determine the creation of 110 rare-earth peak that is nicely compatible with the abundance patterns in the Sun and metal-poor stars. This new finding further strengthens the case of NS mergers as possible dominant origin of r-nuclei with A > 140.

  20. Levels of platinum group elements and rare-earth elements in wild mushroom species growing in Poland.

    PubMed

    Mleczek, Miros?aw; Niedzielski, Przemys?aw; Kala?, Pavel; Siwulski, Marek; Rzymski, Piotr; G?secka, Monika

    2016-01-01

    Due to limited data-describing abilities of mushrooms to accumulate platinum group elements (PGEs) and rare-earth elements (REEs), the aim of this study was to determine, by inductively coupled plasma optical emission spectrometry followed by microwave-assisted sample digestion by nitric acid, the content of these elements in 20 mushroom species (10 above ground and 10 growing on wood), mostly edible, collected near a busy trunk road. The highest content of PGEs in above-ground mushroom species was observed in Lepista gilva and Suillus bovinus fruit bodies (0.38 ± 0.05 and 0.37 ± 0.03 mg kg(-1) DW, respectively), while in mushrooms growing on wood, the highest content was observed in Pleurotus ostreatus (0.35 ± 0.04 mg kg(-1) DW). The mean content of PGEs for both these groups was 0.23 ± 0.08 and 0.26 ± 0.07 mg kg(-1) DW, respectively. The highest content of REEs in Suillus luteus and Tricholoma equestra was 5.03 ± 0.50 and 2.18 ± 0.56 mg kg(-1) DW, respectively, but within mushrooms growing on wood in Ganoderma applanatum fruiting bodies it was 4.19 ± 0.78 mg kg(-1) DW. Mean contents of REEs were 1.39 ± 1.21 and 1.61 ± 0.97 mg kg(-1) DW in above-ground species and species growing on wood, respectively. Generally, the group of mushroom species growing on wood was capable of slightly higher accumulation of both REEs and PGEs. No limits have been established for both the groups until now. PMID:26515437

  1. The impact of vegetation on fractionation of rare earth elements (REE) during waterrock interaction

    E-print Network

    Mailhes, Corinne

    and Sr, Nd isotopic compositions of waters, suspended loads and soils are given in previous papers compared to water and their Sr and Nd isotopic compositions are comparable with those of apatite and waters. Thus, the preferential LREE uptake by the plants at the root­water­soil (apatite) interface might lead

  2. Systematics of metal-silicate partitioning for many siderophile elements applied to Earth’s core formation

    NASA Astrophysics Data System (ADS)

    Siebert, Julien; Corgne, Alexandre; Ryerson, Frederick J.

    2011-03-01

    Superliquidus metal-silicate partitioning was investigated for a number of moderately siderophile (Mo, As, Ge, W, P, Ni, Co), slightly siderophile (Zn, Ga, Mn, V, Cr) and refractory lithophile (Nb, Ta) elements. To provide independent constrains on the effects of temperature, oxygen fugacity and silicate melt composition, isobaric (3 GPa) experiments were conducted in piston cylinder apparatus at temperature between 1600 and 2600 °C, relative oxygen fugacities of IW-1.5 to IW-3.5, and for silicate melt compositions ranging from basalt to peridotite. The effect of pressure was investigated through a combination of piston cylinder and multi-anvil isothermal experiments between 0.5 and 18 GPa at 1900 °C. Oxidation states of siderophile elements in the silicate melt as well as effect of carbon saturation on partitioning are also derived from these results. For some elements (e.g. Ga, Ge, W, V, Zn) the observed temperature dependence does not define trends parallel to those modeled using metal-metal oxide free energy data. We correct partitioning data for solute interactions in the metallic liquid and provide a parameterization utilized in extrapolating these results to the P- T- X conditions proposed by various core formation models. A single-stage core formation model reproduces the mantle abundances of several siderophile elements (Ni, Co, Cr, Mn, Mo, W, Zn) for core-mantle equilibration at pressures from 32 to 42 GPa along the solidus of a deep peridotitic magma ocean (˜3000 K for this pressure range) and oxygen fugacities relevant to the FeO content of the present-day mantle. However, these P- T- fO 2 conditions cannot produce the observed concentrations of Ga, Ge, V, Nb, As and P. For more reducing conditions, the P- T solution domain for single stage core formation occurs at subsolidus conditions and still cannot account for the abundances of Ge, Nb and P. Continuous core formation at the base of a magma ocean at P- T conditions constrained by the peridotite liquidus and fixed fO 2 yields concentrations matching observed values for Ni, Co, Cr, Zn, Mn and W but underestimates the core/mantle partitioning observed for other elements, notably V, which can be reconciled if accretion began under reducing conditions with progressive oxidation to fO 2 conditions consistent with the current concentration of FeO in the mantle as proposed by Wade and Wood (2005). However, neither oxygen fugacity path is capable of accounting for the depletions of Ga and Ge in the Earth's mantle. To better understand core formation, we need further tests integrating the currently poorly-known effects of light elements and more complex conditions of accretion and differentiation such as giant impacts and incomplete equilibration.

  3. Investigating the Partitioning of Inorganic Elements Consumed by Humans between the Various Fractions of Human Wastes: An Alternative Approach

    NASA Technical Reports Server (NTRS)

    Wignarajah, Kanapathipillai; Pisharody, Suresh; Fisher, John W.

    2003-01-01

    The elemental composition of food consumed by astronauts is well defined. The major elements carbon, hydrogen, oxygen, nitrogen and sulfur are taken up in large amounts and these are often associated with the organic fraction (carbohydrates, proteins, fats etc) of human tissue. On the other hand, a number of the elements are located in the extracellular fluids and can be accounted for in the liquid and solid waste fraction of humans. These elements fall into three major categories - cationic macroelements (e.g. Ca, K, Na, Mg and Si), anionic macroelements (e.g. P, S and Cl and 17 essential microelements, (e.g. Fe, Mn, Cr, Co, Cu, Zn, Se and Sr). When provided in the recommended concentrations to an adult healthy human, these elements should not normally accumulate in humans and will eventually be excreted in the different human wastes. Knowledge of the partitioning of these elements between the different human waste fractions is important in understanding (a) developing waste separation technologies, (b) decision-making on how these elements can be recovered for reuse in space habitats, and (c) to developing the processors for waste management. Though considerable literature exists on these elements, there is a lack of understanding and often conflicting data. Two major reasons for these problems include the lack of controlled experimental protocols and the inherently large variations between human subjects (Parker and Gallagher, 1988). We have used the existing knowledge of human nutrition and waste from the available literature and NASA documentation to build towards a consensus to typify and chemically characterize the various human wastes. It is our belief, that this could be a building block towards integrating a human life support and waste processing in a closed system.

  4. Application of rare-earth element Y in refining impure copper

    NASA Astrophysics Data System (ADS)

    Li, Hai-hong; Sun, Xue-qin; Zhang, Shang-zhou; Zhao, Qin-yi; Wang, Guang-zhen

    2015-05-01

    The effects of rare-earth element Y in refining impure copper were investigated in this paper. The composition, microstructures, and corrosion resistance properties of impure copper before and after refinement with Y were investigated using direct-reading spectrometry, inductively coupled plasma atomic emission spectrometry, optical microscopy, scanning electron microscopy, and potentiodynamic polarization measurements. The results show that the concentrations of impurities S, As, Sb, Bi, Al, Cd, and Se are remarkably decreased. Adding an appropriate amount of Y refines the microstructure and enhances the corrosion resistance properties of impure copper in HCl solution via a purification effect. The formation enthalpies of compounds formed between Y and various impurity elements were calculated on the basis of Miedema's theory. The thermodynamic mechanisms of the refinement of impure copper by Y were also discussed

  5. Rare earth elements in chondritic phosphates - Implications for PU-244 chronology

    NASA Astrophysics Data System (ADS)

    Reed, S. J. B.; Long, J. V. P.; Smith, D. G. W.

    1983-11-01

    Ion-probe measurements were made of the rare-earth elements (REE) in chondritic phosphates. A 20-micron beam of O-16(-) ions was used to bombard thin phosphate sections. A computer-controlled mass spectrometer was employed to analyze the peaks generated by the beam scan. When interferences from matrixes in the samples were encountered, the intensities of major isotopes were compared with reference intensities, and the peaks of isotopes showing the lowest interference were selected. REE concentrations of apatite and merrillite in Barbotan and Salles chondrites are reported, showing that REE is five times higher in concentration than apatite. It is concluded that the REE elements can be successfully substituted as a Pu analog for dating the chondritic phosphate materials in regards to their formation time.

  6. Geochemistry of rare earth elements in Permian coals from the Huaibei Coalfield, China

    NASA Astrophysics Data System (ADS)

    Zheng, Liugen; Liu, Guijian; Chou, Chen-Lin; Qi, Cuicui; Zhang, Ying

    2007-10-01

    The rare earth elements (REEs) in coals are important because of: (a) REE patterns can be an indicator of the nature of source rocks of the mineral matter as well as sedimentary environments; (b) REEs abundance in coal may have industrial-significance. In this study, a total of thirty-four samples of Permian coal, partings, roof, and floor were collected from the Huaibei Coalfield, Anhui Province, China. Abundances of rare earth elements (REEs) and other elements in the samples were determined by inductively coupled-plasma mass spectrometry (ICP-MS) and inductively coupled-plasma atomic emission spectrometry (ICP-AES). The results show that the REEs are enriched in coals in the Huaibei Coalfield as compared with Chinese and U.S. coals and the world coal average. Coals in the Lower Shihezi Formation (No. 7, 5, and 4 Coals) and Upper Shihezi Formation (No. 3) have higher REE abundances than the coals in Shanxi Formation (No. 10). Magmatic intrusion resulted in high enrichment of REEs concentrations in No. 5 and 7 Coals. The REE abundances are positively correlated with the ash content. The mineral matter in these coals is mainly made up of clay minerals and carbonates. The REEs are positively correlated with lithophile elements including Si, Al, Ti, Fe, and Na, which are mainly distributed in clay minerals, indicating that REEs are contained mainly in clay minerals. The REE abundances in coals normalized by the ash are higher than that in partings. REEs abundances of coals cannot be accounted for by the REE content in the mineral matter, and some REEs associated with organic matter in coals.

  7. Geochemistry of rare earth elements in Permian coals from the Huaibei Coalfield, China

    USGS Publications Warehouse

    Zheng, Lingyun; Liu, Gaisheng; Chou, C.-L.; Qi, C.; Zhang, Y.

    2007-01-01

    The rare earth elements (REEs) in coals are important because of: (a) REE patterns can be an indicator of the nature of source rocks of the mineral matter as well as sedimentary environments; (b) REEs abundance in coal may have industrial-significance. In this study, a total of thirty-four samples of Permian coal, partings, roof, and floor were collected from the Huaibei Coalfield, Anhui Province, China. Abundances of rare earth elements (REEs) and other elements in the samples were determined by inductively coupled-plasma mass spectrometry (ICP-MS) and inductively coupled-plasma atomic emission spectrometry (ICP-AES). The results show that the REEs are enriched in coals in the Huaibei Coalfield as compared with Chinese and U.S. coals and the world coal average. Coals in the Lower Shihezi Formation (No. 7, 5, and 4 Coals) and Upper Shihezi Formation (No. 3) have higher REE abundances than the coals in Shanxi Formation (No. 10). Magmatic intrusion resulted in high enrichment of REEs concentrations in No. 5 and 7 Coals. The REE abundances are positively correlated with the ash content. The mineral matter in these coals is mainly made up of clay minerals and carbonates. The REEs are positively correlated with lithophile elements including Si, Al, Ti, Fe, and Na, which are mainly distributed in clay minerals, indicating that REEs are contained mainly in clay minerals. The REE abundances in coals normalized by the ash are higher than that in partings. REEs abundances of coals cannot be accounted for by the REE content in the mineral matter, and some REEs associated with organic matter in coals. ?? 2007 Elsevier Ltd. All rights reserved.

  8. Fractionation of highly siderophile elements in refertilized mantle: Implications for the Os isotope composition of basalts

    NASA Astrophysics Data System (ADS)

    Marchesi, Claudio; Dale, Christopher W.; Garrido, Carlos J.; Pearson, D. Graham; Bosch, Delphine; Bodinier, Jean-Louis; Gervilla, Fernando; Hidas, Károly

    2014-08-01

    Highly fertile lherzolite and spinel websterite in the Ronda peridotite massif are enriched in Pt and Pd compared to Os, Ir, Ru and Re. The fractionation of the highly siderophile elements (HSE) in these rocks was produced by reaction of melt with their peridotite and pyroxenite precursors. Modeling indicates that upon reaction primary HSE hosts were dissolved and magmatic sulphides precipitated, largely erasing the original HSE signature of reacting protoliths. The budget of HSE in the melt was controlled by sulphide-silicate partitioning or entrainment of molten sulphide in silicate melt. Rhenium was likely removed from precursor peridotite and pyroxenite by previous melt extraction. Refertilization of peridotite by melts increased Al2O3, CaO, Pt, Pd contents and 187Os/188Os beyond typical values for mantle peridotite and the primitive upper mantle. The interaction of melts with residual peridotite and pyroxenite, as illustrated in the Ronda massif, can generate radiogenic-Os-enriched domains in the mantle with high melt productivity, higher Pt/Os and Pt/Re than common peridotite, and lower Re/Os than typical pyroxenite. As also previously proposed for pyroxenites, these “hybrid” domains can account for the difference in Os isotope compositions between many basalts (e.g., MORB and OIB) and common depleted mantle peridotites. Moreover, the presence of these enriched hybrid components in the mantle, evolved over sufficient timescales and in geologically reasonable proportions, may account for the 186Os-187Os enrichment of plume lavas without requiring a chemical contribution from the core.

  9. An EDTA-?-cyclodextrin material for the adsorption of rare earth elements and its application in preconcentration of rare earth elements in seawater.

    PubMed

    Zhao, Feiping; Repo, Eveliina; Meng, Yong; Wang, Xueting; Yin, Dulin; Sillanpää, Mika

    2016-03-01

    The separation and recovery of Rare earth elements (REEs) from diluted aqueous streams has attracted great attention in recent years because of ever-increasing REEs demand. In this study, a green synthesized EDTA-cross-linked ?-cyclodextrin (EDTA-?-CD) biopolymer was prepared and employed in adsorption of aqueous REEs, such as La(III), Ce(III), and Eu(III). EDTA acts not only as cross-linker but also as coordination site for binding of REEs. The adsorption properties for the adsorption of REEs by varying experimental conditions were carried out by batch tests. The kinetics results revealed that the surface chemical sorption and the external film diffusion were the rate-determining steps of the adsorption process. The obtained maximum adsorption capacities of EDTA-?-CD were 0.343, 0.353, and 0.365mmolg(-1) for La(III), Ce(III) and Eu(III), respectively. Importantly, the isotherms fitted better to Langmuir than Freundlich and Sips models, suggesting a homogenous adsorption surface for REEs on the adsorbent. Moreover, the multi-component adsorption, which was modeled by extended Sips isotherms, revealed adsorbent's selectivity to Eu(III). More significantly, the successful recoveries of the studied ions from tap water and seawater samples makes EDTA-?-CD a promising sorbent for the preconcentration of REEs from diluted aqueous streams. PMID:26674238

  10. Rare earth element variations resulting from inversion of pigeonite and subsolidus reequilibration in lunar ferroan anorthosites

    USGS Publications Warehouse

    James, O.B.; Floss, C.; McGee, J.J.

    2002-01-01

    We present results of a secondary ion mass spectrometry study of the rare earth elements (REEs) in the minerals of two samples of lunar ferroan anorthosite, and the results are applicable to studies of REEs in all igneous rocks, no matter what their planet of origin. Our pyroxene analyses are used to determine solid-solid REE distribution coefficients (D = CREE in low-Ca pyroxene/CREE in augite) in orthopyroxene-augite pairs derived by inversion of pigeonite. Our data and predictions from crystal-chemical considerations indicate that as primary pigeonite inverts to orthopyroxene plus augite and subsolidus reequilibration proceeds, the solid-solid Ds for orthopyroxene-augite pairs progressively decrease for all REEs; the decrease is greatest for the LREEs. The REE pattern of solid-solid Ds for inversion-derived pyroxene pairs is close to a straight line for Sm-Lu and turns upward for REEs lighter than Sm; the shape of this pattern is predicted by the shapes of the REE patterns for the individual minerals. Equilibrium liquids calculated for one sample from the compositions of primary phases, using measured or experimentally determined solid-liquid Ds, have chondrite-normalized REE patterns that are very slightly enriched in LREEs. The plagioclase equilibrium liquid is overall less rich in REEs than pyroxene equilibrium liquids, and the discrepancy probably arises because the calculated plagioclase equilibrium liquid represents a liquid earlier in the fractionation sequence than the pyroxene equilibrium liquids. "Equilibrium" liquids calculated from the compositions of inversion-derived pyroxenes or orthopyroxene derived by reaction of olivine are LREE depleted (in some cases substantially) in comparison with equilibrium liquids calculated from the compositions of primary phases. These discrepancies arise because the inversion-derived and reaction-derived pyroxenes did not crystallize directly from liquid, and the use of solid-liquid Ds is inappropriate. The LREE depletion of the calculated liquids is a relic of formation of these phases from primary LREE-depleted minerals. Thus, if one attempts to calculate the compositions of equilibrium liquids from pyroxene compositions, it is important to establish that the pyroxenes are primary. In addition, our data suggest that experimental studies have underestimated solid-liquid Ds for REEs in pigeonite and that REE contents of liquids calculated using these Ds are overestimates. Our results have implications for Sm-Nd age studies. Our work shows that if pigeonite inversion and/or subsolidus reequilibration between augite and orthopyroxene occured significantly after crystallization, and if pyroxene separates isolated for Sm-Nd studies do not have the bulk composition of the primary pyroxenes, then the Sm-Nd isochron age and ??Nd will be in error. Copyright ?? 2002 Elsevier Science Ltd.

  11. Earth Observatory Satellite system definition study. Report no. 5: System design and specifications. Part 1: Observatory system element specifications

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The performance, design, and quality assurance requirements for the Earth Observatory Satellite (EOS) Observatory and Ground System program elements required to perform the Land Resources Management (LRM) A-type mission are presented. The requirements for the Observatory element with the exception of the instruments specifications are contained in the first part.

  12. Comparison of the partitioning behaviours of yttrium, rare earth elements, and titanium between hydrogenetic marine ferromanganese crusts and seawater

    USGS Publications Warehouse

    Bau, M.; Koschinsky, A.; Dulski, P.; Hein, J.R.

    1996-01-01

    In order to evaluate details of the partitioning behaviours of Y, rare earth elements (REEs), and Ti between inorganic metal oxide surfaces and seawater, we studied the distribution of these elements in hydrogenetic marine ferromanganese (Fe-Mn) crusts from the Central Pacific Ocean. Nonphosphatized Fe-Mn crusts display shale-normalized rare earths and yttrium (REYSN) patterns (Y inserted between Dy and Ho) that are depleted in light REEs (LREEs) and which show negative anomalies for YSN, and positive anomalies for LaSN, EuSN, GdSN, and in most cases, CeSN. They show considerably smaller Y/ Ho ratios than seawater or common igneous and clastic rocks, indicating that Y and Ho are fractionated in the marine environment. Compared to P-poor crusts, REYSN patterns of phosphatized Fe-Mn crusts are similar, but yield pronounced positive YSN anomalies, stronger positive LaSN anomalies, and enrichment of the HREEs relative to the MREEs. The data suggest modification of REY during phosphatization and indicate that studies requiring primary REY distributions or isotopic ratios should be restricted to nonphosphatized (layers of) Fe-Mn crusts. Apparent bulk coefficients, KMD, describing trace metal partitioning between nonphosphatized hydrogenetic Fe-Mn crusts and seawater, are similar for Pr to Eu and decrease for Eu to Yb. Exceptionally high values of KCeD, which are similar to those of Ti, result from oxidative scavenging of Ce and support previous suggestions that Ce(IV) is a hydroxide-dominated element in seawater. Yttrium and Gd show lower KD values than their respective neighbours in the REY series. Results of modelling the exchange equilibrium between REY dissolved in seawater and REY sorbed on hydrous Fe-Mn oxides corroborate previous studies that suggested the surface complexation of REY can be approximated by their first hydroxide binding constant. Negative "anomalies" occur for stabilities of bulk surface complexes of Gd, La, and particularly Y. The differences in inorganic surface complex stability between Y and Ho and between Gd and its REE neighbours are similar to those shown by the stabilities of complexes with aminocarboxylic acids and are significantly larger than those shown by stabilities of complexes with carboxylic acids. Hence, sorption of Y and REEs onto hydrous Fe-Mn oxides may contribute significantly to the positive YSN and GdSN anomalies in seawater.

  13. Road-deposited sediments in an urban environment: A first look at sequentially extracted element loads in grain size fractions.

    PubMed

    Sutherland, Ross A; Tack, Filip M G; Ziegler, Alan D

    2012-07-30

    Sediments stored in urban drainage basins are important environmental archives for assessing contamination. Few studies have examined the geochemical fractionation of metals in individual grain size classes of solid environmental media. This is the first study of road sediments to quantify the mass loading of Al, Cu, Pb, and Zn in individual grain size classes (<63?m to 1000-2000?m) and partition contributions amongst four sequentially extracted fractions (acid extractable, reducible, oxidizable, and residual). The optimized BCR sequential extraction procedure was applied to road sediments from Palolo Valley, Oahu, Hawaii. Road sediments from this non-industrialized drainage basin exhibited significant enrichment in Cu, Pb, and Zn. Metal mass loading results indicate that the <63?m grain size class dominated almost all fraction loads for a given element. The residual fraction dominated the Al loading for this geogenic element. The reducible fraction, associated with Fe and Mn oxides, was the most important component for Cu, Pb, and Zn loading. These results have direct implications for environmental planners charged with reducing sediment-associated contaminant transport in urbanized drainage basins. PMID:22609391

  14. Electrical and dielectric properties of lithium manganate nanomaterials doped with rare-earth elements

    NASA Astrophysics Data System (ADS)

    Iqbal, Muhammad Javed; Ahmad, Zahoor

    2008-05-01

    Substituted LiRxMn2 - xO4 (R = La3+, Ce3+, Pr3+ and x = 0.00 - 0.20) nanoparticles are prepared by the sol-gel method and the consequent changes in their lattice structure, dielectric and electrical parameters are determined by XRD, ED-XRF, SEM, LCR meter bridge and dc electrical resistivity measurements. Diffraction data show that the samples are single-phase spinel materials with crystallites sizes between 21 and 38 nm. The lattice parameter, cell volume and X-ray density are found to be affected by doping the Li-manganate with the rare-earth elements. The ED-XRF analysis confirms the stoichiometric composition of the synthesized samples and SEM reveals their morphology. Calculated values of the dielectric constant (?) and the dielectric loss (tan ?) decrease with the frequency of the applied field. This is attributed to Maxwell-Wagner polarization. Replacement of manganese by the rare-earth elements results in an improvement in the structural stability of the material, which is considered to be useful for enhancement of the cycleability of the compounds when used in lithium rechargeable batteries, and increases significantly the values of ? and tan ? (except for Ce). Lithium manganate nanomaterials with high ? and low tan ? may be attractive for application in memory storage devices.

  15. While China's dominance in rare earths dips, concerns remain about these and other elements

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-05-01

    China's dominance in the production of rare earth elements (REEs) peaked with that nation producing 97% of them in 2010; this number already has dipped to 90% in 2012 as mines in other nations are coming online, according to REE expert Karl Gschneidner Jr., a professor at Iowa State University's Ames Laboratory. Chinese production could drop to 60% by 2014, with production increasing at mines in the United States and other countries, he said. However, this reduction in China's share of REE production does not signal an end to the production crisis in REEs and other critical minerals, Gschneidner and others noted during a 1 May panel discussion on critical materials shortages at the AGU Science Policy Conference in Washington, D. C. REEs are a group of 17 chemically similar metallic elements used in a variety of electronic, optical, magnetic, and catalytic applications, and despite their name, they are relatively plentiful in the Earth's crust. China's control of known REE reserves has dropped from 75% in 1975 to 30.9% in 2012, with other regions also having large reserves, including the Commonwealth of Independent States (some former Soviet Republic states), the United States, and Australia, according to Gschneidner. Critical minerals are mineral commodities that are particularly important for a nation's economy or national defense that could potentially face supply disruptions.

  16. Rare earth elements in soils from selected areas on the Island of Hawaii

    SciTech Connect

    Barnard, W.M.; Halbig, J.B.

    1985-07-01

    Fifty soil samples for the wet, windward (east) side and dry, leeward (west) side of the Island of Hawaii were analyzed for La, Ce, Sm, Eu, Yb, and Lu by neutron activation/gamma-ray spectroscopic analysis. Data on concentrations in each sample are listed and analyzed statistically for soil samples collected from the western slope of Kohala Mountain, the western coastal plain of Mauna Kea, and the Northeastern coastal plain of Maunal Loa. Rare earth element (REE) concentrations are two to six times greater in soils from the western, dry side of the island, and good statistical correlation is exhibited among the samples for pairs of individual REEs. In the organic-rich soils of the east side, correlations are poor but are markedly improved when sample weights are adjusted for weight due to organic matter and water in soil colloids. If the mean compositions of selected rock samples from the Hawaii Reference Suite are representative of the compositions of the parent materials, REEs in the soils are moderately enriched (up to two times, based on oven-dry weights). Rare earth element concentrations in the island's western soils are as much as two times greater than the mean REE values of common sedimentary rocks worldwide; however, they are well within the concentration ranges of soils of continental origin. The eastern soils tend to have less La and Ce, but similar amounts of the middle and heavy REEs.

  17. Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

    PubMed

    Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

    2015-01-01

    Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 ?m broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. PMID:25278442

  18. Identifying calcium sources at an acid deposition-impacted spruce forest: A strontium isotope, alkaline earth element multi-tracer approach

    USGS Publications Warehouse

    Bullen, T.D.; Bailey, S.W.

    2005-01-01

    Depletion of calcium from forest soils has important implications for forest productivity and health. Ca is available to fine feeder roots from a number of soil organic and mineral sources, but identifying the primary source or changes of sources in response to environmental change is problematic. We used strontium isotope and alkaline earth element concentration ratios of trees and soils to discern the record of Ca sources for red spruce at a base-poor, acid deposition-impacted watershed. We measured 87Sr/86Sr and chemical compositions of cross-sectional stemwood cores of red spruce, other spruce tissues and sequential extracts of co-located soil samples. 87Sr/86Sr and Sr/Ba ratios together provide a tracer of alkaline earth element sources that distinguishes the plant-available fraction of the shallow organic soils from those of deeper organic and mineral soils. Ca/Sr ratios proved less diagnostic, due to within-tree processes that fractionate these elements from each other. Over the growth period from 1870 to 1960, 87Sr/86Sr and Sr/Ba ratios of stemwood samples became progressively more variable and on average trended toward values that considered together are characteristic of the uppermost forest floor. In detail the stemwood chemistry revealed an episode of simultaneous enhanced uptake of all alkaline earth elements during the growth period from 1930 to 1960, coincident with reported local and regional increases in atmospheric inputs of inorganic acidity. We attribute the temporal trends in stemwood chemistry to progressive shallowing of the effective depth of alkaline earth element uptake by fine roots over this growth period, due to preferential concentration of fine roots in the upper forest floor coupled with reduced nutrient uptake by roots in the lower organic and upper mineral soils in response to acid-induced aluminum toxicity. Although both increased atmospheric deposition and selective weathering of Ca-rich minerals such as apatite provide possible alternative explanations of aspects of the observed trends, the chemical buffering capacity of the forest floor-biomass pool limits their effectiveness as causal mechanisms. ?? Springer 2005.

  19. Distribution characteristics of rare earth elements in children's scalp hair from a rare earths mining area in southern China.

    PubMed

    Tong, Shi-Lu; Zhu, Wang-Zhao; Gao, Zhao-Hua; Meng, Yu-Xiu; Peng, Rui-Ling; Lu, Guo-Cheng

    2004-01-01

    In order to demonstrate the validity of using scalp hair rare earth elements (REEs) content as a biomarker of human REEs exposure, data were collected on REEs exposure levels from children aged 11-15 years old and living in an ion-adsorptive type light REEs (LREEs) mining and surrounding areas in southern China. Sixty scalp hair samples were analyzed by ICP-MS for 16 REEs (La Lu, Y and Sc). Sixteen REEs contents in the samples from the mining area (e.g., range: La: 0.14-6.93 microg/g; Nd: 0.09-5.27 microg/g; Gd: 12.2-645.6ng/g; Lu: 0.2-13.3 ng/g; Y: 0.03-1.27 microg/g; Sc: 0.05-0.30 microg/g) were significantly higher than those from the reference area (range: La: 0.04-0.40 microg/g; Nd: 0.04-0.32 microg/g; Gd: 8.3-64.6 ng/g; Lu: 0.4-3.3ng/g; Y: 0.03-0.29 microg/g; Sc: 0.11-0.36 microg/g) and even much higher than those published in the literature. The distribution pattern of REEs in scalp hair from the mining area was very similar to that of REEs in the mine and the atmosphere shrouding that area. In conclusion, the scalp hair REEs contents may indicate not only quantitatively but also qualitatively (distribution pattern) the absorption of REEs from environmental exposure into human body. The children living in this mining area should be regarded as a high-risk group with REEs (especially LREEs) exposure, and their health status should be examined from a REEs health risk assessment perspective. PMID:15478941

  20. Cracking the Code of Soil Genesis. The Early Role of Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Zaharescu, D. G.; Dontsova, K.; Burghelea, C. I.; Maier, R. M.; Huxman, T. E.; Chorover, J.

    2014-12-01

    Soil is terrestrial life support system. Its genesis involves tight interactions between biota and mineral surfaces that mobilize structural elements into biogeochemical cycles. Of all chemical elements rare earth elements (REE) are a group of 16 non-nutrient elements of unusual geochemical similarity and present in all components of the surface environment. While much is known about the role of major nutrients in soil development we lack vital understanding of how early biotic colonization affects more conservative elements such as REE. A highly controlled experiment was set up at University of Arizona's Biosphere-2 that tested the effect of 4 biological treatments, incorporating a combination of microbe, grass, mycorrhiza and uninoculated control on REE leaching and uptake in 4 bedrock substrates: basalt, rhyolite, granite and schist. Generally the response of REE to biota presence was synergistic. Variation in total bedrock chemistry could explain major trends in pore water REE. There was a fast transition from chemistry-dominated to a biota dominated environment in the first 3-4 months of inoculation/seeding which translated into increase in REE signal over time. Relative REE abundances in water were generally reflected in plant concentrations, particularly in root, implying that below ground biomass is the main sync of REE in the ecosystem. Mycorrhiza effect on REE uptake in plant organs was significant and increased with infection rates. Presence of different biota translated into subtle differences in REE release, reveling potential biosignatures of biolota-rock colonization. The results thus bring fundamental insight into early stages non-nutrient cycle and soil genesis.

  1. Earth

    NASA Technical Reports Server (NTRS)

    Carr, M. H.

    1984-01-01

    The following aspects of the planet Earth are discussed: plate tectonics, the interior of the planet, the formation of the Earth, and the evolution of the atmosphere and hydrosphere. The Earth's crust, mantle, and core are examined along with the bulk composition of the planet.

  2. Comparison of single and sequential extraction procedures for the study of rare earth elements remobilisation in different types of soils.

    PubMed

    Rao, Chebrolu Rama Mohan; Sahuquillo, Angels; Lopez-Sanchez, Jose Fermin

    2010-03-10

    With the continual increase in the utilisation of rare earth elements (REE) for industrial and agricultural purposes, research into the environmental and biogeochemical behaviour of REE had attracted much interest in recent times. This study principally describes the distribution of REE in four different types of soils like lateritic soil (S-1), in situ natural soil (S-2), soil contaminated by mining activity (S-3) and accidentally polluted soil (S-4) utilizing the optimised BCR sequential extraction procedure and partial extractions with various types of single extractants such as unbuffered salt solutions 0.1 M NaNO(3), 0.01 M CaCl(2), 1 M NH(4)NO(3); complexing agents 0.005 M DTPA and 0.05 M EDTA; acid solutions 0.43 M CH(3)COOH and 1 M HCl. Comparison of the sum of the four BCR fractions, which included an aqua regia attack on the residue, with the pseudo-total aqua regia digest values to assess the accuracy of the BCR partioning approach has been undertaken. Partial extraction results with several single extractants have also been reported for all the REE elements including yttrium which have been analysed by the optimised BCR procedure. Results obtained after 24 h extraction with each of the single extractant have also been discussed. The extraction with 1 M HCl during 24 h yielded similar quantities of REE as those released under the combined steps of 1, 2 and 3 of the BCR sequential extraction for all the four different type of soil samples indicating that this reagent can be used successfully to estimate the total extractable contents of REE in various types of soil samples. PMID:20171311

  3. Rare-earth element geochemistry and the origin of andesites and basalts of the Taupo Volcanic Zone, New Zealand

    USGS Publications Warehouse

    Cole, J.W.; Cashman, K.V.; Rankin, P.C.

    1983-01-01

    Two types of basalt (a high-Al basalt associated with the rhyolitic centres north of Taupo and a "low-Al" basalt erupted from Red Crater, Tongariro Volcanic Centre) and five types of andesite (labradorite andesite, labradorite-pyroxene andesite, hornblende andesite, pyroxene low-Si andesite and olivine andesite/low-Si andesite) occur in the Taupo Volcanic Zone (TVZ), North Island, New Zealand. Rare-earth abundances for both basalts and andesites are particularly enriched in light rare-earth elements. High-Al basalts are more enriched than the "low-Al" basalt and have values comparable to the andesites. Labradorite and labradorite-pyroxene andesites all have negative Eu anomalies and hornblende andesites all have negative Ce anomalies. The former is probably due to changing plagioclase composition during fractionation and the latter to late-stage hydration of the magma. Least-squares mixing models indicate that neither high-Al nor "low-Al" basalts are likely sources for labradorite/labradorite-pyroxene andesites. High-Al basalts are considered to result from fractionation of olivine and clinopyroxene from a garnet-free peridotite at the top of the mantle wedge. Labradorite/labradorite-pyroxene andesites are mainly associated with an older NW-trending arc. The source is likely to be garnet-free but it is not certain whether the andesites result from partial melting of the top of the subducting plate or a hydrated lower portion of the mantle wedge. Pyroxene low-Si andesites probably result from cumulation of pyroxene and calcic plagioclase within labradorite-pyroxene andesites, and hornblende andesites by late-stage hydration of labradorite-pyroxene andesite magma. Olivine andesites, low-Si andesites and "low-Al" basalts are related to the NNE-trending Taupo-Hikurangi arc structure. Although the initial source material is different for these lavas they have probably undergone a similar history to the labradorite/labradorite-pyroxene andesites. All lavas show evidence of crustal contamination. ?? 1983.

  4. Post-depositional redistribution processes and their effects on middle rare earth element precipitation and the cerium anomaly in sediments in the South Korea Plateau, East Sea

    NASA Astrophysics Data System (ADS)

    Kang, Jeongwon; Jeong, Kap-Sik; Cho, Jin Hyung; Lee, Jun Ho; Jang, Seok; Kim, Seong Ryul

    2014-03-01

    We sampled two box-core sediments from the slope of the eastern South Korea Plateau (SKP) in the East Sea (Sea of Japan) at water depths of 1400 and 1700 m. Two chemical fractions of extractable (hydroxylamine/acetic acid) and residual rare earth elements (REEs) together with Al, Ca, Fe, Mg, Mn, P, S, As, Mo, and U were analyzed to assess the post-depositional redistribution of REEs. Extractable Fe and Mn are noticeably abundant in the oxic topmost sediment layer (<3 cm). However, some trace elements (e.g., S, As, Mo, U) are more abundant at depth, where redox conditions are different. Analysis of upper continental crust (UCC)-normalized (La/Gd)UCC, (La/Yb)UCC, and (Ce/Ce*)UCC revealed that the extractable REE is characterized by middle REE (MREE) enrichment and a positive cerium (Ce) anomaly, different from the case of the residual fraction which shows slight enrichment in light REEs (LREEs) with no Ce anomaly. The extractable MREEs seem to have been incorporated into high-Mg calcite during reductive dissolution of Fe oxyhydroxides. In the top sediment layer, the positive Ce anomaly is attributed to Ce oxide, which can be mobilized in deeper oxygen-poor environments and redistributed in the sediment column. In addition, differential concentrations of Ce and other LREEs in pore water appear to result in variable (Ce/Ce*)UCC ratios in the extractable fraction at depth.

  5. Elemental analysis of soluble and insoluble fractions of river-waters by particle-induced X-ray emission

    NASA Astrophysics Data System (ADS)

    Yamazaki, H.; Ishii, K.; Matsuyama, S.; Takahashi, Y.; Sasaki, T.; Orihara, H.; Izumi, Y.

    1999-06-01

    A procedure has been developed and tested for PIXE analysis of soluble and insoluble constituents in river-water samples. Three kinds of targets were prepared and analyzed with a PIXE system of 3-MeV proton beam. Insoluble components were filtered on a Nuclepore filter of 0.4-?m pores. For soluble fractions, a target of major components was made from a 0.15-ml filtrate evaporated on a user-made polycarbonate film and trace amounts of heavy metals were preconcentrated in a PIXE-target by means of a combination of dibenzyldithiocarbamate-chelation with subsequent condensation into dibenzylidene-D-sorbitol gels. The widespread concentrations (several tenths of ppb to a few tens of ppm) of ˜24 elements from Na to Pb were determined simultaneously in a precision sufficient to reveal the elemental distribution between the soluble and insoluble fractions of river waters. Hence, the methodology can be applied to monitor a pollution problem of rivers.

  6. 'Nano' Morphology and Element Signatures of Early Life on Earth: A New Tool for Assessing Biogenicity

    NASA Technical Reports Server (NTRS)

    Oehler, D. Z.; Mostefaoui, S.; Meibom, A.; Selo, M.; McKay, D. S.; Robert, F.

    2006-01-01

    The relatively young technology of NanoSIMS is unlocking an exciting new level of information from organic matter in ancient sediments. We are using this technique to characterize Proterozoic organic material that is clearly biogenic as a guide for interpreting controversial organic structures in either terrestrial or extraterrestrial samples. NanoSIMS is secondary ion mass spectrometry for trace element and isotope analysis at sub-micron resolution. In 2005, Robert et al. [1] combined NanoSIMS element maps with optical microscopic imagery in an effort to develop a new method for assessing biogenicity of Precambrian structures. The ability of NanoSIMS to map simultaneously the distribution of organic elements with a 50 nm spatial resolution provides new biologic markers that could help define the timing of life s development on Earth. The current study corroborates the work of Robert et al. and builds on their study by using NanoSIMS to map C, N (as CN), S, Si and O of both excellently preserved microfossils and less well preserved, non-descript organics in Proterozoic chert from the ca. 0.8 Ga Bitter Springs Formation of Australia.

  7. Grain Boundary Segregation of Rare-Earth Elements in Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Robson, Joseph D.; Haigh, Sarah J.; Davis, Bruce; Griffiths, David

    2015-10-01

    Small additions of rare-earth (RE) elements have been shown to have a powerful effect in modifying the texture of wrought magnesium alloys, giving a highly beneficial effect in improving their formability. Recent work has shown that segregation of RE atoms to grain boundaries is important in producing this texture change. In this work, two Mg-RE systems have been studied Mg-Y and Mg-Nd using high-resolution scanning transmission electron microscopy that permits both imaging and elemental analysis with a spatial resolution of better than 0.1 nm. The Mg-Y alloy, where the solubility and level of addition are relatively high, showed the RE texture change effect. This was accompanied by clustering of Y on the grain boundaries, consistent with previous studies of the Mg-Gd system. The Mg-Nd alloy, where the solubility and level of addition are relatively low, showed no texture change and no segregation. In this case, impurity elements binding the RE into insoluble particles, rendering it ineffective. The results are analyzed by modifying a previous model for the solute drag effect on boundaries expected due to the RE additions. This predicts that both Gd and Y will strongly inhibit boundary motion, with Gd being approximately twice as effective as Y.

  8. Trace Element Fractional Solubility in Ultrapure Water From Samples Collected During the US GEOTRACES Eastern Tropical South Pacific Section

    NASA Astrophysics Data System (ADS)

    Buck, C. S.; Landing, W. M.; Aguilar-Islas, A. M.; Rember, R.

    2014-12-01

    The US GEOTRACES section cruise to the Eastern Tropical South Pacific (GP16) embarked from Manta, Ecuador on October 25, 2013 and terminated in Papeete, Tahiti on December 22, 2013. Bulk and size fractionated aerosol samples were collected over seventeen 72-hour periods on cellulose filters using Tisch high volume samplers. The bulk samples were collected on 47mm W41 filters and the size fractionated samples on slotted impactor filters. The Sierra-style slotted cascade impactor cutoffs are >7µm, >3µm, >1.5µm, >0.95µm and >0.49µm. Particles <0.49µm were collected on a 20 x 25cm W41 backing filter. The soluble bulk aerosol fraction was extracted aboard ship by passing 100mL of ultrapure water (>18.2M? cm) through the sample filter under vacuum. The extract was acidified for storage and later analyzed by ICP-MS to quantify the soluble aerosol fraction. Replicate bulk filters collected simultaneously were digested and analyzed by ICP-MS to provide the total aerosol concentration. Our data will provide insight into the nature of aerosols transported across the South Pacific and describe their potential as a source for trace elements to the surface ocean. The results will aid in the interpretation of surface water trace element concentrations. We will also characterize the alteration of aerosol fractional solubility with transport in the atmosphere as well as investigate the relationship between aerosol concentration and aerosol fractional solubility. All of our observations will be discussed in the context of the larger global dataset of aerosol solubility data and compared with assumptions currently applied in global models of atmospheric deposition.

  9. Study on the electrochemical extraction of rare earth elements from FLINAK

    SciTech Connect

    Long, Dewu; Huang, Wei; Jiang, Feng; Tian, Lifang; Li, Qingnuan

    2013-07-01

    Electrochemical behaviors of rare earth elements, such as NdF{sub 3}, GdF{sub 3}, SmF{sub 3}, YF{sub 3}, and EuF{sub 3}, were investigated in a LiF-NaF-KF (46.5-11.5-42.0 mol %, FLINAK, m. p. 454 Celsius degrees) solvent. The results indicated that it is possible to extract Nd, Gd and Y directly by electrochemical deposition since the reductions of those cations to metal are located in the electrochemical window of the FLINAK eutectic, while the reductions of Sm and Eu metal are out of the range of the medium. Subsequently electro-deposition of Nd was carried out with two kinds of cathodic materials, namely, an inert cathode, Pt, and a reactive electrode, Cu. The collected products were characterized by various techniques revealing that a Nd-rich product was obtained. (authors)

  10. Behavior of Rare Earth Element In Geothermal Systems; A New Exploration/Exploitation Tool

    SciTech Connect

    Scott A. Wood

    2002-01-28

    The goal of this four-year project was to provide a database by which to judge the utility of the rare earth elements (REE) in the exploration for and exploitation of geothermal fields in the United States. Geothermal fluids from hot springs and wells have been sampled from a number of locations, including: (1) the North Island of New Zealand (1 set of samples); (2) the Cascades of Oregon; (3) the Harney, Alvord Desert and Owyhee geothermal areas of Oregon; (4) the Dixie Valley and Beowawe fields in Nevada; (5) Palinpion, the Philippines: (6) the Salton Sea and Heber geothermal fields of southern California; and (7) the Dieng field in Central Java, Indonesia. We have analyzed the samples from all fields for REE except the last two.

  11. Origin of middle rare earth element enrichment in acid mine drainage-impacted areas.

    PubMed

    Grawunder, Anja; Merten, Dirk; Büchel, Georg

    2014-01-01

    The commonly observed enrichment of middle rare earth elements (MREE) in water sampled in acid mine drainage (AMD)-impacted areas was found to be the result of preferential release from the widespread mineral pyrite (FeS2). Three different mining-impacted sites in Europe were sampled for water, and various pyrite samples were used in batch experiments with diluted sulphuric acid simulating AMD-impacted water with high sulphate concentration and high acidity. All water samples independent on their origin from groundwater, creek water or lake water as well as on the surrounding rock types showed MREE enrichment. Also the pyrite samples showed MREE enrichment in the respective acidic leachate but not always in their total contents indicating a process-controlled release. It is discussed that most probably complexation to sulphite (SO3 (2-)) or another intermediate S-species during pyrite oxidation is the reason for the MREE enrichment in the normalized REE patterns. PMID:24385183

  12. Rare earths, other trace elements and iron in Luna 20 samples.

    NASA Technical Reports Server (NTRS)

    Helmke, P. A.; Blanchard, D. P.; Jacobs, J. W.; Haskin, L.; Haskin, A.

    1973-01-01

    The results of the analysis by neutron activation of six samples from the Luna 20 mission and one sample of less than 1 mm fines from Apollo 16 are reported. The concentrations of the rare-earth elements (REE) in the samples of fines from Luna 20 and Apollo 16 are less than those found for corresponding materials from the mare areas but a negative Eu anomaly is still present. The concentrations of the REE in fines from Luna 20 are only about two-thirds as great as in the sample of Apollo 16 fines, but the concentration of Co, Sc and Cr are greater by factors ranging from 1.5 to 2.3.

  13. Rare earth and trace element geochemistry of a fragment of Jurassic seafloor, Point Sal, California

    NASA Technical Reports Server (NTRS)

    Menzies, M.; Blanchard, D.; Brannon, J.; Korotev, R.

    1977-01-01

    Rocks from an ophiolite suite once on the seafloor were analyzed for rare earth elements (REE), Sc, Co, Na2O, Cr, Zn and FeO. Strontium isotope exchange noted in some of the lavas is attributed to basalt-seawater interaction; the Ce abundance in smectite- and zeolite-bearing lavas may also be due to prolonged exposure to seawater. The higher grades of metamorphic rock, however, show no variation from the usual flat or slightly light REE depleted profiles. Plutonic igneous rock, all light REE depleted, have total REE abundances varying by a factor of 100 between the dunites and diorites. In order of decreasing REE abundance are hornblende, clinopyroxene, plagioclase, orthopyroxene and olivine. Calculations of REE contents of liquids in equilibrium with early cumulative clinopyroxenes suggest that the parent to the stratiform sequence was more depleted in light REE than the parent to the lava pile.

  14. Anthropogenic rare earth element fluxes into floodplains: Coupling between geochemical monitoring and hydrodynamic sediment transport modelling

    NASA Astrophysics Data System (ADS)

    Hissler, Christophe; Hostache, Renaud; Iffly, Jean François; Pfister, Laurent; Stille, Peter

    2015-09-01

    As all rare earth elements (REEs) have an increasingly important role in high tech industries, they are now recognized as emergent pollutants in river systems impacted by anthropogenic activity. Over the past 20 years, significant anthropogenic contributions were reported for Gd, La and Sm, and we may expect that REE contamination in rivers is to further increase in a near future. Despite the work done to assess the environmental impact of REE pollutions in larger river systems, we are still lacking information on the dynamics of these anthropogenic compounds in relation to hydrological changes. Here, we observed for the first time particulate Ce originating from local industrial activities in Luxembourg and we quantified the anthropogenic contribution to the REE fluxes at the river basin scale during a single flood event.

  15. X-ray fluorescence analysis of rare earth elements in rocks using low dilution glass beads.

    PubMed

    Nakayama, Kenichi; Nakamura, Toshihiro

    2005-07-01

    Major and trace elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, Fe, Rb, Sr, Y, Zr, La, Ce, Pr, Nd, Sm, Gd, Dy, Th and U) in igneous rocks were assayed with fused lithium borate glass beads using X-ray fluorescence spectrometry. Low dilution glass beads, which had a 1:1 sample-to-flux ratio, were prepared for determination of rare earth elements. Complete vitrification of 1:1 mixture required heating twice at 1200 degrees C with agitation. Extra pure reagents containing determinants were used for calibrating standards instead of the rock standard. The calibration curves of the 23 elements showed good linearity. Furthermore, the lower limits of detection corresponding to three times the standard deviation for blank measurements were 26 mass ppm for Na2O, 6.7 for MgO, 4.5 for Al2O3, 4.5 for SiO2, 18 for P2O5, 1.1 for K2O, 4.0 for CaO, 3.9 for TiO2, 1.6 for MnO, 0.8 for Fe2O3, 0.5 for Rb, 0.2 for Sr, 0.4 for Y, 0.5 for Zr, 3.3 for La, 6.5 for Ce, 2.7 for Pr, 2.1 for Nd, 1.7 for Sm, 0.7 for Gd, 2.7 for Dy, 0.5 for Th, and 0.6 for U. Using the present method, we determined the contents of these 23 elements in four rhyolitic and granitic rocks from Japan. PMID:16038502

  16. Extreme trace elements fractionation in Cenozoic nephelinites and phonolites from the Moroccan Anti-Atlas (Eastern Saghro)

    NASA Astrophysics Data System (ADS)

    Berger, Julien; Ennih, Nasser; Liégeois, Jean-Paul

    2014-12-01

    Nephelinites and phonolites from the Moroccan Anti-Atlas form a cogenetic series of volcanic rocks linked by a fractional crystallization process and showing continuous evolutionary trends for trace-elements. According to partial melting calculations, minor element data in olivine and review of published experimental studies, the most primitive nephelinites are low degree (~ 2%) partial melts from a carbonated LREE-rich spinel lherzolite. Sr-Nd-Pb isotopic compositions indicate the participation of both DM and HIMU end-members in the mantle source of nephelinites; the HIMU component is here interpreted as a relic of the shallow metasomatized Pan-African mantle. The phonolites show similar isotopic composition except for slightly more radiogenic Sr isotopic values. Fractional crystallization calculations were performed using trace-element mineral/bulk rock coefficients determined with new LA-ICP-MS data on minerals together with published equilibrium partition coefficients. The decrease of LREE, Sr and Ba with increasing differentiation is explained by fractionation of large amounts of apatite. Th, Nb and Zr display a behavior of very incompatible elements, reaching extreme concentration in most differentiated phonolites. Ta, Hf and MREE by contrast are characterized by a moderately incompatible to compatible behavior during differentiation. Fractionation of small amount of titanite, in which Ta, Hf and MREE are highly compatible compared to Nb, Zr and LREE (DNb/DTa: 2, DZr/DHf: 1.5 for titanite/phonolite ratios), explains the observed increase in Nb/Ta and Zr/Hf ratios with increasing silica content, from 18 and 40 in nephelinites to 70 and 80 in phonolites, respectively. Clinopyroxene also contributed to the fractionation of Hf from Zr in the very first steps of crystallization. The low values of Nb/Ta and Zr/Hf ratios observed in the two most differentiated Si-rich phonolites are probably a consequence of late stage segregation of volatile-rich agpaitic assemblages in the underlying magma chamber. Two phonolites with extreme Sr contents plot outside fractionation trends, as a result of the remelting of previously crystallized nephelinitic rocks in depth.

  17. Natural radioactivity and rare earth elements in feldspar samples, Central Eastern desert, Egypt.

    PubMed

    Walley El-Dine, Nadia; El-Shershaby, Amal; Afifi, Sofia; Sroor, Amany; Samir, Eman

    2011-05-01

    The pegmatite bodies of the Eastern Desert of Egypt are widely distributed especially along the Marsa-Alam-Idfu road. The Abu Dob area covers about 150km(2) of the Arabian Nubian shield at the central part of the Eastern Desert of Egypt. Most of the pegmatite is zoned; the zonation starts with milky quartz at the core followed by alkali feldspar at the margins. The feldspars vary in color from rose to milky and in composition from K-feldspar to Na-feldspar, sometimes interactions of both types are encountered. Thirteen feldspar samples were collected from different locations in the Abu Dob area for measuring the natural radioactivity of (238)U, (232)Th and (40)K using an HPGe detector. The variation in concentration of radionuclides for the area under investigation can be classified into regions of high, medium and low natural radioactivity. The average concentration in BqKg(-1) has been observed to be from 9.5 to 183675.7BqKg(-1) for (238)U, between 6.1 and 94,314.2BqKg(-1) for (232)Th and from 0 to 7894.6BqKg(-1) for (40)K. Radium equivalent activities (Ra(eq)), dose rate (D(R)) and external hazard (H(ex)) have also been determined. In the present work, the concentration of rare earth elements are measured for two feldspar samples using two techniques, Environmental Scanning Electron microscope XIL 30 ESEM, Philips, and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The existence of rare earth elements in this area are very high and can be used in different important industries. PMID:21324705

  18. Determination of Earth structure using waveform inversion and Spectral-Element Method for Eastern Asian region

    NASA Astrophysics Data System (ADS)

    Tsuboi, S.; Obayashi, M.; Tono, Y.; Suetsugu, D.

    2011-12-01

    Recent progress in large scale computing by using Spectral-Element Method and the Earth Simulator has demonstrated possibilities to perform full-waveform inversion of three dimensional (3D) seismic velocity structure inside the Earth. Specifically Liu and Tromp (2006) have shown that it becomes feasible to compute finite frequency kernel for seismic velocity structure based on adjoint method. We apply their method to obtain 3D velocity structure beneath East Asia. We take one chunk from global mesh of Spectral-Element Method and compute synthetic seismograms with accuracy of about 10 second. We use GAP-P2 mantle tomography model (Obayashi et al., 2009) as an initial 3D model and try to use as many broadband seismic stations available in this region, including Ocean Bottom Seismographs deployed in Philippine sea, as possible to perform inversion. We calculate synthetic seismograms for this initial 3D model and source receiver pairs. We then use the time windows for P and S waves to compute adjoint sources and calculate misfit adjoint kernels for seismic velocity structure. The kernels are calculated for all the time windows of P and S waves simultaneously. We sum up the event misfit kernels and perform the first iteration to improve the initial velocity model using the steepest decent method. The results of the first iteration shows that the differences between the initial model and the improved model is less than 1%, which shows that the modification resulted from the first iteration was quite modest. However the modifications to the initial model show different pattern among P-waves and S-waves, which implies that the scaling relation to obtain S-waves velocity model from P-wave velocity model might be revised in this region.

  19. Geology and market-dependent significance of rare earth element resources

    NASA Astrophysics Data System (ADS)

    Simandl, G. J.

    2014-09-01

    China started to produce rare earth elements (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare earth element export quotas first introduced by the Chinese government in the early 2000s were severely reduced in 2010 and 2011. This led to strong government-created disparity between prices within China and the rest of the world. Industrialized countries identified several REEs as strategic metals. Because of rapid price increases of REE outside of China, we have witnessed a world-scale REE exploration rush. The REE resources are concentrated in carbonatite-related deposits, peralkaline igneous rocks, pegmatites, monazite ± apatite veins, ion adsorption clays, placers, and some deep ocean sediments. REE could also be derived as a by-product of phosphate fertilizer production, U processing, mining of Ti-Zr-bearing placers, and exploitation of Olympic Dam subtype iron oxide copper gold (IOCG) deposits. Currently, REEs are produced mostly from carbonatite-related deposits, but ion adsorption clay deposits are an important source of heavy REE (HREE). Small quantities of REE are derived from placer deposits and one peralkaline intrusion-related deposit. The ideal REE development targets would be located in a politically stable jurisdiction with a pro-mining disposition such as Canada and Australia. REE grade, HREE/light REE (LREE) ratio of the mineralization, tonnage, mineralogy, and permissive metallurgy are some of the key technical factors that could be used to screen potential development projects. As REEs are considered strategic metals from economic, national security, and environmental points of view, technical and economic parameters alone are unlikely to be used in REE project development decision-making. Recycling of REE is in its infancy and unless legislated, in the short term, it is not expected to contribute significantly to the supply of REE.

  20. Geology and market-dependent significance of rare earth element resources

    NASA Astrophysics Data System (ADS)

    Simandl, G. J.

    2014-12-01

    China started to produce rare earth elements (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare earth element export quotas first introduced by the Chinese government in the early 2000s were severely reduced in 2010 and 2011. This led to strong government-created disparity between prices within China and the rest of the world. Industrialized countries identified several REEs as strategic metals. Because of rapid price increases of REE outside of China, we have witnessed a world-scale REE exploration rush. The REE resources are concentrated in carbonatite-related deposits, peralkaline igneous rocks, pegmatites, monazite ± apatite veins, ion adsorption clays, placers, and some deep ocean sediments. REE could also be derived as a by-product of phosphate fertilizer production, U processing, mining of Ti-Zr-bearing placers, and exploitation of Olympic Dam subtype iron oxide copper gold (IOCG) deposits. Currently, REEs are produced mostly from carbonatite-related deposits, but ion adsorption clay deposits are an important source of heavy REE (HREE). Small quantities of REE are derived from placer deposits and one peralkaline intrusion-related deposit. The ideal REE development targets would be located in a politically stable jurisdiction with a pro-mining disposition such as Canada and Australia. REE grade, HREE/light REE (LREE) ratio of the mineralization, tonnage, mineralogy, and permissive metallurgy are some of the key technical factors that could be used to screen potential development projects. As REEs are considered strategic metals from economic, national security, and environmental points of view, technical and economic parameters alone are unlikely to be used in REE project development decision-making. Recycling of REE is in its infancy and unless legislated, in the short term, it is not expected to contribute significantly to the supply of REE.

  1. A major light rare-earth element (LREE) resource in the Khanneshin carbonatite complex, southern Afghanistan

    USGS Publications Warehouse

    Tucker, Robert D.; Belkin, Harvey E.; Schulz, Klaus J.; Peters, Stephen G.; Horton, Forrest; Buttleman, Kim; Scott, Emily R.

    2012-01-01

    The rapid rise in world demand for the rare-earth elements (REEs) has expanded the search for new REE resources. We document two types of light rare-earth element (LREE)-enriched rocks in the Khanneshin carbonatite complex of southern Afghanistan: type 1 concordant seams of khanneshite-(Ce), synchysite-(Ce), and parisite-(Ce) within banded barite-strontianite alvikite, and type 2 igneous dikes of coarse-grained carbonatite, enriched in fluorine or phosphorus, containing idiomorphic crystals of khanneshite-(Ce) or carbocernaite. Type 1 mineralized barite-strontianite alvikite averages 22.25 wt % BaO, 4.27 wt % SrO, and 3.25 wt % ? LREE2O3 (sum of La, Ce, Pr, and Nd oxides). Type 2 igneous dikes average 14.51 wt % BaO, 5.96 wt % SrO, and 3.77 wt % ? LREE2O3. A magmatic origin is clearly indicated for the type 2 LREE-enriched dikes, and type 1 LREE mineralization probably formed in the presence of LREE-rich hydrothermal fluid. Both types of LREE mineralization may be penecontemporaneous, having formed in a carbonate-rich magma in the marginal zone of the central vent, highly charged with volatile constituents (i.e., CO2, F, P2O5), and strongly enriched in Ba, Sr, and the LREE. Based on several assumptions, and employing simple geometry for the zone of LREE enrichment, we estimate that at least 1.29 Mt (million metric tonnes) of LREE2O3 is present in this part of the Khanneshin carbonatite complex.

  2. Planktonic foraminiferal rare earth elements as a potential new aeolian dust proxy

    NASA Astrophysics Data System (ADS)

    Chou, C.; Liu, Y.; Lo, L.; Wei, K.; Shen, C.

    2012-12-01

    Characteristics of rare earth elements (REEs) have widely been used as important tracers in many fields of earth sciences, including lithosphere research, environmental change, ocean circulation and other natural carbonate materials. Foraminiferal test REE signatures have been suggested to reflect ambient seawater conditions and serve as valuable proxies in the fields of paleoceanography and paleoclimate. Here we present a 60-kyr planktonic foraminifera Globigerinoides ruber (white, 250-300 ?m) REE record of a sediment core MD05-2925 (9°20.61'S, 151°27.61'E, water depth 1660 m) from the Solomon Sea. The REE diagram shows two dominant sources of local seawater and nearby terrestrial input. The variability of foraminiferal REE/Ca time series is different from Mg/Ca-inferred sea surface temperature and ?18O records during the past 60-kyr. This inconsistency suggests that planktonic foraminiferal REE content cannot result only from changes in ice volume and temperature. Synchroneity between high planktonic foraminiferal REE content and Antarctic ice core dust amount record implies the same dust sources, probably from Australia or mainland China. Our results suggest that foraminiferal REE can potentially be as a new dust proxy and record dry/humid conditions at the source area.

  3. A New Fungal Isolate, Penidiella sp. Strain T9, Accumulates the Rare Earth Element Dysprosium

    PubMed Central

    Horiike, Takumi

    2015-01-01

    With an aim to develop a highly efficient method for the recovery of rare earth elements (REEs) by using microorganisms, we attempted to isolate dysprosium (Dy)-accumulating microorganisms that grow under acidic conditions from environmental samples containing high concentrations of heavy metals. One acidophilic strain, T9, which was isolated from an abandoned mine, decreased the concentration of Dy in medium that contained 100 mg/liter Dy to 53 mg/liter Dy after 3 days of cultivation at pH 2.5. The Dy content in the cell pellet of the T9 strain was 910 ?g/mg of dry cells. The T9 strain also accumulated other REEs. Based on the results of 28S-D1/D2 rRNA gene sequencing and morphological characterization, we designated this fungal strain Penidiella sp. T9. Bioaccumulation of Dy was observed on the cell surface of the T9 strain by elemental mapping using scanning electron microscopy-energy dispersive X-ray spectroscopy. Our results indicate that Penidiella sp. T9 has the potential to recover REEs such as Dy from mine drainage and industrial liquid waste under acidic conditions. PMID:25710372

  4. A new fungal isolate, Penidiella sp. strain T9, accumulates the rare earth element dysprosium.

    PubMed

    Horiike, Takumi; Yamashita, Mitsuo

    2015-05-01

    With an aim to develop a highly efficient method for the recovery of rare earth elements (REEs) by using microorganisms, we attempted to isolate dysprosium (Dy)-accumulating microorganisms that grow under acidic conditions from environmental samples containing high concentrations of heavy metals. One acidophilic strain, T9, which was isolated from an abandoned mine, decreased the concentration of Dy in medium that contained 100 mg/liter Dy to 53 mg/liter Dy after 3 days of cultivation at pH 2.5. The Dy content in the cell pellet of the T9 strain was 910 ?g/mg of dry cells. The T9 strain also accumulated other REEs. Based on the results of 28S-D1/D2 rRNA gene sequencing and morphological characterization, we designated this fungal strain Penidiella sp. T9. Bioaccumulation of Dy was observed on the cell surface of the T9 strain by elemental mapping using scanning electron microscopy-energy dispersive X-ray spectroscopy. Our results indicate that Penidiella sp. T9 has the potential to recover REEs such as Dy from mine drainage and industrial liquid waste under acidic conditions. PMID:25710372

  5. Geochemistry of the rare earth elements in ferromanganese nodules from DOMES Site A, northern equatorial Pacific

    USGS Publications Warehouse

    Calvert, S.E.; Piper, D.Z.; Baedecker, P.A.

    1987-01-01

    The distribution of rare earth elements (REE) in ferromanganese nodules from DOMES Site A has been determined by instrumental neutron activation methods. The concentrations of the REE vary markedly. Low concentrations characterize samples from a depression (the valley), in which Quaternary sediments are thin or absent; high concentrations are found in samples from the surrounding abyssal hills (the highlands) where the Quaternary sediment section is relatively thick. Moreover, the valley nodules are strongly depleted in the light trivalent REE (LREE) and Ce compared with nodules from the highlands, some of the former showing negative Ce anomalies. The REE abundances in the nodules are strongly influenced by the REE abundances in coexisting bottom water. Some controls on the REE chemistry of bottom waters include: a) the more effective removal of the LREE relative to the HREE from seawater because of the greater degree of complexation of the latter elements with seawater ligands, b) the very efficient oxidative scavenging of Ce on particle surfaces in seawater, and c) the strong depletion of both Ce and the LREE in, or a larger benthic flux of the HREE into, the Antarctic Bottom Water (AABW) which flows through the valley. The distinctive REE chemistry of valley nodules is a function of their growth from geochemically evolved AABW. In contrast, the REE chemistry of highland nodules indicates growth from a local, less evolved seawater source. ?? 1987.

  6. Study of K?2 /K?1 RYIED in closed and open shell Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Chaves, P. C.; Tribolet, A. D.; Reis, M. A.

    2016-01-01

    Relative Yield Ion Energy Dependence (RYIED) was observed, named and reported as phenomenological evidence in 2005 (Reis et al., 2005). Since then, it was observed in transitions to the same subshell, and plausible explanations for the physics behind the phenomena have been proposed. In this work we present experimental evidence of the RYIED effect on the most inner transition possible in two Rare Earth Elements (REE), namely variations in the intensity ratio of K?2 /K?1 X-rays from Tm and Yb irradiated under different conditions. These REE are particularly interesting to start with since Yb has an electronic configuration where all the subshells are completely filled, whilst Tm misses one electron in the 4f subshell. Ultrapure oxides of each element were irradiated using proton beams having energies in the range of 0.9-3.6 MeV, in steps of 100 keV. Spectra were collected using the CdTe detector of the HRHE-PIXE set-up of C2TN and analysed using the DT2 code. Finally, the vanishing of the effect upon charging up of the target has been observed and will be discussed.

  7. The determination of scandium, yttrium, and selected rare earth elements in geological materials by inductively coupled plasma optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Bolton, Alexander; Hwang, Jack; Voet, Anthony Vander

    The spectroscopic determination of rare earth elements (REE's) in geological matrices is generally complicated by the relatively low concentrations of these elements, the high concentrations or matrix elements and their interferences in the analyte determination and a lack of well-defined usable concentration values for reference rock materials, especially at low REE concentrations. This paper describes work being carried out at the Geoscience Laboratories, Ontario Geological Survey, on the determination of Sc, Y, and selected rare earth elements at both high concentration and chondrite levels by inductively coupled plasma optical emission spectrometry. Direct acid digestate solutions (for high concentrations) and ion exchange separated solutions (for chondrite levels) are analyzed by a multichannel ICP spectrometer system: typical results for reference standards and samples are presented and compared.

  8. Using rare earth elements for the identification of the geographic origin of food

    NASA Astrophysics Data System (ADS)

    Meisel, T.; Bandoniene, D.; Joebstl, D.

    2009-04-01

    The European Union defined regimes within the Protected Geographical Status (PGS) framework to protect names of regional food specialities. Thus only food produced in a specific geographical area with a specific way of production or quality can be protected by a protected geographical indication (PGI) label. As such Styrian Pumpkin Seed Oil has been approved with this label, but as with many other high priced regional specialities, fraud cannot be excluded or nor identified. Thus the aim of this work is, to develop an analytical method for the control of the geographic origin of pumpkin seed oil and also to test the method for other protected products. The development of such a method is not only of interest for scientists, but also of importance for the consumer wanting to know the origin of the food products and the assurance of the purity and quality. The group of rare earth elements (REE) in plants also have a characteristic distribution pattern similar to upper crustal REE distributions. Since the REE concentrations are extremely low in pumpkin seed oil (ppt to low ppb), ICP-MS was the only sensitive tool able to produce validated results. The carrier of the REE are most likely small particles distributed within the pumpkin seed oil. Unlike, e.g., olive oil, pumpkin seed oil is bottled and sold unfiltered, which makes this Styrian speciality an interesting sampling target. As pumpkin seed oils from different geographic origin show variable trace element and rare earth distribution patterns, is should possible to trace the origin of these oils. In the current project pumpkin seeds from different regions in Austria and from abroad were sampled. The trace element patterns in the extracted oil of these seeds were determined and a preliminary classification with discriminate analysis was successfully done on a statistical basis. In addition to the study of the geographic origin it was demonstrated that REE distribution patterns can also be used for the identification of adulteration of high priced pumpkin seed oil with cheap neutral tasting refined oils. Interestingly enough, the variations of the REE patterns between oils from different regions are much more pronounced than their host soils. Thus we assume that microbiological processes in the rhizosphere are in control of the REE uptake into the plant. Regional variations of the microbiological composition of the soils and probably not only a priori the bulk soil composition of the minerals in the soil are the cause of the regional variations making it possible to identify the geographic origin of pumpkin seeds and as a consequence the pumpkin seed oil.

  9. Trace elements and REE fractionation in subsoils developed on sedimentary and volcanic rocks: case study of the Mt. Vulture area, southern Italy

    NASA Astrophysics Data System (ADS)

    Mongelli, Giovanni; Paternoster, Michele; Rizzo, Giovanna; Sinisi, Rosa

    2014-06-01

    There is an increasing interest in the distribution of rare earth elements (REEs) within soils, primarily as these elements can be used to identify pedogenetic processes and because soils may be future sources for REE extraction, despite much attention should be paid to the protection and preservation of present soils. Here, we evaluate the processes that control the distribution of REEs in subsoil horizons developed over differing lithologies in an area of low anthropogenic contamination, allowing estimates of the importance of source rocks and weathering. Specifically, this study presents new data on the distribution of REEs and other trace elements, including transition and high-field-strength elements, in subsoils developed on both Quaternary silica-undersaturated volcanic rocks and Pliocene siliciclastic sedimentary rocks within the Mt. Vulture area of the southern Apennines in Italy. The subsoils in the Mt. Vulture area formed during moderate weathering (as classified using the chemical index of alteration) and contain an assemblage of secondary minerals that is dominated by trioctahedral illite with minor vermiculite. The REEs, high-field-strength elements, and transition metals have higher abundances in subsoils that developed from volcanic rocks, and pedogenesis caused the Mt. Vulture subsoils to have REE concentrations that are an order of magnitude higher than typical values for the upper continental crust. This result indicates that the distribution of REEs in soils is a valuable tool for mineral exploration. A statistical analysis of inter-elemental relationships indicates that REEs are concentrated in clay-rich fractions that also contain significant amounts of low-solubility elements such as Zr and Th, regardless of the parent rock. This suggests that low-solubility refractory minerals, such as zircon, play a significant role in controlling the distribution of REEs in soils. The values of (La/Yb)N and (Gd/Yb)N fractionation indices are dependent on the intensity of pedogenesis; soils in the study area have values that are higher than typical upper continental crust ratios, suggesting that soils, especially those that formed during interaction with near neutral to acidic organic-rich surface waters, may represent an important source of both light REEs and medium REEs (MREEs). In comparison, MREE/heavy REE fractionation in soils that form during moderate weathering may be affected by variations in parent rock lithologies, primarily as MREE-hosting minerals, such as pyroxenes, may control (La/Sm)N index values. Eu anomalies are thought to be the most effective provenance index for sediments, although the anomalies within the soils studied here are not related to the alteration of primary minerals, including feldspars, to clay phases. In some cases, Eu/Eu* values may have a weak correlation with elements hosted by heavy minerals, such as Zr; this indicates that the influence of mechanical sorting of clastic particles during sedimentary transport on the Eu/Eu* values of siliciclastic sediments needs to be considered carefully.

  10. Linking rare earth element zoning in major and accessory minerals to better understand metasedimentary migmatites

    NASA Astrophysics Data System (ADS)

    Matthews, J. A.; Kelly, N. M.; Koenig, A.; Harley, S. L.

    2011-12-01

    Trace element signatures from major and accessory minerals are increasingly used to place constraints on the ages of tectonothermal events and gain insights into processes operating in the deep continental crust. Minerals such as garnet, zircon or monazite represent sensitive recorders of events if a solid understanding exists of what trace element signatures represent. A study underway on granulite facies migmatites is providing insights into trace element signatures in garnet, and when integrated with in situ, microbeam analysis of zircon and monazite, is allowing a complex polymetamorphic history to be deciphered. The Larsemann Hills, east Antarctica, are composed of felsic orthogneisses and metasediments that were affected by high-grade metamorphism and partial melting at c. 7 kbar and >800 °C. Initially interpreted to have experienced a single cycle of metamorphism at c. 550-530 Ma, recent ages suggest that the area was affected by an earlier high-grade event at c. 900 Ma; the timing of migmatization relative to these two events remains uncertain. To address this, a detailed study has targeted metasedimentary migmatites. Garnet, zircon and monazite were analysed from melanosome, leucosome and selvage domains. Garnet (predominantly almandine-pyrope) preserves little, if any, major element zoning. In contrast, it records systematic within-grain variations in heavy rare earth element (HREE) concentration depending on textural context. Garnet within residuum domains displays broad cores with flat HREE slopes in chondrite-normalized plots, but are HREE-depleted (negative slopes) at boundaries adjacent to leucosome. In contrast, garnet boundaries adjacent to cordierite-rich selvages are typically HREE-enriched, with positive-sloping patterns. It is interpreted that core-rim depletions in HREE may reflect evolution of the whole-rock reservoir towards depletion during migmatization and garnet growth. Enrichment in garnet HREE adjacent to selvage domains likely resulted from local reaction between solids and melts either during melt transit and/or crystallization. Monazite, which is preferentially located in leucosome domains, preserves ages that reflect growth at c. 900 Ma and c. 530 Ma, although trace element signatures are ambiguous. However, zircon, which is preferentially located in selvage domains, preserves c. 530 Ma rims with depleted, flat to negatively sloping HREE patterns. It is interpreted that these zircon rims grew in, or near to equilibrium with garnet cores and rims during partial melting, and may date at least part of migmatite formation in the Larsemann Hills. They do not date the final crystallization of melts and development of selvage domains. Preliminary results of this study have shown that the trace element composition of garnet from high-temperature terrains can be a powerful tool in tracking metamorphic and melting processes where major elements zoning is no longer preserved. This study also demonstrates the utility of textural context when interpreting trace element patterns and ages from dateable accessory minerals in rocks from polycyclic metamorphic terrains.

  11. Rare earth elements (REEs): effects on germination and growth of selected crop and native plant species.

    PubMed

    Thomas, Philippe J; Carpenter, David; Boutin, Céline; Allison, Jane E

    2014-02-01

    The phytotoxicity of rare earth elements (REEs) is still poorly understood. The exposure-response relationships of three native Canadian plant species (common milkweed, Asclepias syriaca L., showy ticktrefoil, Desmodium canadense (L.) DC. and switchgrass, Panicum virgatum L.) and two commonly used crop species (radish, Raphanus sativus L., and tomato, Solanum lycopersicum L.) to the REEs lanthanum (La), yttrium (Y) and cerium (Ce) were tested. In separate experiments, seven to eight doses of each element were added to the soil prior to sowing seeds. Effects of REE dose on germination were established through measures of total percent germination and speed of germination; effects on growth were established through determination of above ground biomass. Ce was also tested at two pH levels and plant tissue analysis was conducted on pooled samples. Effects on germination were mostly observed with Ce at low pH. However, effects on growth were more pronounced, with detectable inhibition concentrations causing 10% and 25% reductions in biomass for the two native forb species (A. syriaca and D. canadense) with all REEs and on all species tested with Ce in both soil pH treatments. Concentration of Ce in aboveground biomass was lower than root Ce content, and followed the dose-response trend. From values measured in natural soils around the world, our results continue to support the notion that REEs are of limited toxicity and not considered extremely hazardous to the environment. However, in areas where REE contamination is likely, the slow accumulation of these elements in the environment could become problematic. PMID:23978671

  12. Rare earth element mobility during prograde granulite facies metamorphism: significance of fluorine

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Fleet, Michael E.

    1996-04-01

    Mafic gneisses occur as lenses or thin layers in spatial association with tonalitic leucosomes in a granulite zone of the Quetico subprovince of the Superior Province, Ontario, Canada, and exhibit concentric zoning with a biotite-rich margin, orthopyroxene-rich outer zone, clinopyroxene-rich central zone, and, occasionally, patches of relict amphibolites within the clinopyroxene-rich zone. The granulites (biotite-, orthopyroxene- and clinopyroxene-rich zones) in the mafic gneisses are characterized by significant amounts of rare earth element (REE)-bearing fluorapatite (1 10 vol.%) and other REE-rich minerals (allanite, monazite and zircon). Fluorapatite shows an increase in modal abundance from the biotite- and orthopyroxene-rich zones to the clinopyroxene-rich zone, but is rare in the relict amphibolites. Textural evidence and element partitioning indicate that fluorapatite (and other REE-rich minerals) was part of the peak metamorphic assemblages. Whole-rock geochemical analyses confirm that the granulites in the mafic gneisses contain anomalously high contents of REE and high field strength elements (HFSE), whereas the relict amphibolites are geochemically typical of tholeiitic basalts. Mass-balance calculations reveal that REE and HFSE were introduced into the mafic gneisses during the prograde granulite facies metamorphism, pointing to REE mobility under granulite facies metamorphic conditions. The presence of high F contents in the REE-rich minerals and their associated minerals (e.g. biotite and hornblende) suggests that REE and HFSE may have been transported as fluoride complexes during the granulite facies metamorphism. This conclusion is supported by previously published results of hydrothermal experiments on the partitioning of REE between fluorapatite and F-rich fluids at 700°C and 2 kbar.

  13. First Principles Calculation on Equilibrium Si Isotope Fractionation Factors and its Implementation on Si Isotope Distributions in Earth Surface Environments

    NASA Astrophysics Data System (ADS)

    Liu, Y.; He, H. T.; Zhu, C.

    2014-12-01

    Several important equilibrium Si isotope fractionation factors are calculated here. We use a so-called volume-variable-cluster-model (VVCM) method for solids and the "water-droplet" method for aqueous species for isotope fractionation calculation at the same quantum chemistry level. The calculation results show that several silicate minerals, such as quartz, feldspar, kaolinite, etc., all enrich heavy Si isotopes relative to aqueous H4SiO4 and can be up to 3.3‰ at 25°C, different from most field observations. Meanwhile stable organosilicon complexes can enrich even lighter Si isotopes than aqueous H4SiO4. For explaining the difference between the calculation results and field observations, we calculate the kinetic isotope effect (KIE) associated with the formation of amorphous silica, and find that amorphous silica will enrich extremely light Si isotopes. From amorphous silica to crystalline quartz, the structural adjustment & transition needs getting rid of small amount of Si to re-organize the structure. Light Si isotopes will be preferentially lost and let the final crystalline quartz with a little bit more heavy Si isotopes. However, such late-stage Si heavy isotope enrichment cannot erase the total isotopic signal, crystalline quartz still inherit much light Si isotopic composition from amorphous quartz. That is the reason for the discrepancy between the calculation results and the field observations, because the formation of amorphous quartz is under a non-equilibrium process but theoretical calculations are for equilibrium isotope fractionations. With accurate equilibrium fractionation factors provided here, Si isotope distributions in earth surface environments including soil, groundwater and plants can be further interpreted. We find that ?30Si variations in soil are mainly driven by secondary minerals precipitation and adsorption. Also, bulk soil ?30Si maybe have a parabolic distribution with soil age, with a minimum value at where allophane is completely dissolved and the total amount of sesqui-oxides and poorly crystalline minerals reach their maximum. Similarly, precipitation of clay minerals can explain ?30Si variation in ground water profile.

  14. Fe-Silicide Phases in Polymict Ureilites: Siderophile Trace Element Fractionation

    NASA Astrophysics Data System (ADS)

    Downes, H.; Rai, N.; Smith, C. L.; Herrin, J. S.; Ross, A. J.

    2015-07-01

    We analysed siderophile elements in suessite in polymict ureilites by LA-ICPMS. It is depleted in incompatible siderophiles and patterns resemble those of Si-bearing metals in monomict ureilites. Suessite formed from pre-existing ureilitic metal.

  15. Ultra-low rare earth element content in accreted ice from sub-glacial Lake Vostok, Antarctica

    NASA Astrophysics Data System (ADS)

    Gabrielli, Paolo; Planchon, Frederic; Barbante, Carlo; Boutron, Claude F.; Petit, Jean Robert; Bulat, Sergey; Hong, Sungmin; Cozzi, Giulio; Cescon, Paolo

    2009-10-01

    This paper reports the first rare earth element (REE) concentrations in accreted ice refrozen from sub-glacial Lake Vostok (East Antarctica). REE were determined in various sections of the Vostok ice core in order to geochemically characterize its impurities. Samples were obtained from accreted ice and, for comparison, from the upper glacier ice of atmospheric origin (undisturbed, disturbed and glacial flour ice). REE concentrations ranged between 0.8-56 pg g -1 for Ce and 0.0035-0.24 pg g -1 for Lu in glacier ice, and between <0.1-24 pg g -1 for Ce and <0.0004-0.02 pg g -1 for Lu in accreted ice. Interestingly, the REE concentrations in the upper accreted ice (AC 1; characterized by visible aggregates containing a mixture of very fine terrigenous particles) and in the deeper accreted ice (AC 2; characterized by transparent ice) are lower than those in fresh water and seawater, respectively. We suggest that such ultra-low concentrations are unlikely to be representative of the real REE content in Lake Vostok, but instead may reflect phase exclusion processes occurring at the ice/water interface during refreezing. In particular, the uneven spatial distribution (on the order of a few cm) and the large range of REE concentrations observed in AC 1 are consistent with the occurrence/absence of the aggregates in adjacent ice, and point to the presence of solid-phase concentration/exclusion processes occurring within separate pockets of frazil ice during AC 1 formation. Interestingly, if the LREE enrichment found in AC 1 was not produced by chemical fractionation occurring in Lake Vostok water, this may reflect a contribution of bedrock material, possibly in combination with aeolian dust released into the lake by melting of the glacier ice. Collectively, this valuable information provides new insight into the accreted ice formation processes, the bedrock geology of East Antarctica as well as the water chemistry and circulation of Lake Vostok.

  16. Ultra-low rare earth element content in accreted ice from sub-glacial Lake Vostok, Antarctica

    NASA Astrophysics Data System (ADS)

    Barbante, C.; Gabrielli, P.; Turetta, C.; Planchon, F.; Boutron, C.; Petit, J. R.; Bulat, S.; Hong, S.; Cozzi, G.; Cescon, P.

    2009-12-01

    We report the first rare earth element (REE) concentrations in accreted ice refrozen from sub-glacial Lake Vostok (East Antarctica). REE were determined in various sections of the Vostok ice core in order to geochemically characterize its impurities. Samples were obtained from accreted ice and, for comparison, from the upper glacier ice of atmospheric origin (undisturbed, disturbed and glacial flour ice). REE concentrations ranged between 0.8-56 pg g-1 for Ce and 0.0035- 0.24 pg g-1 for Lu in glacier ice, and between <0.1-24 pg g-1 for Ce and <0.0004-0.02 pg g-1 for Lu in accreted ice. Interestingly, the REE concentrations in the upper accreted ice (AC1;characterized by visible aggregates containing a mixture of very fine terrigenous particles) and in the deeper accreted ice (AC2; characterized by transparent ice) are lower than those in fresh water and seawater, respectively. We suggest that such ultra-low concentrations are unlikely to be representative of the real REE content in Lake Vostok, but instead may reflect phase exclusion processes occurring at the ice/water interface during refreezing. In particular, the uneven spatial distribution (on the order of a few cm) and the large range of REE concentrations observed in AC1 are consistent with the occurrence/absence of the aggregates in adjacent ice, and point to the presence of solid-phase concentration/exclusion processes occurring within separate pockets of frazil ice during AC1 formation. Interestingly, if the LREE enrichment found in AC1 was not produced by chemical fractionation occurring in Lake Vostok water, this may reflect a contribution of bedrock material, possibly in combination with aeolian dust released into the lake by melting of the glacier ice. Collectively, this valuable information provides new insight into the accreted ice formation processes, the bedrock geology of East Antarctica as well as the water chemistry and circulation of Lake Vostok.

  17. Adsorption of rare earth elements onto bacterial cell walls and its implication for REE sorption onto natural microbial mats

    E-print Network

    Hattori, Kéiko H.

    Adsorption of rare earth elements onto bacterial cell walls and its implication for REE sorption Received 8 May 2004; received in revised form 7 January 2005; accepted 15 February 2005 Abstract Adsorption. The occurrence of M-type tetrad effect suggests that REE form inner sphere complexes during their adsorption onto

  18. Using Rare Earth Element (REE) tracers to identify perferential micro-sites of post-fire aeolian erosion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant communities in desert environments are spatially anisotropic. We applied Rare Earth Element (REE) tracers to different landscape positions of an anisotropic Northern Chihuahua Desert ecosystem in an effort to study preferential sediment source areas. We delineated three 0.5 m by 6 m plots of...

  19. A chemical-spectrochemical method for the determination of rare earth elements and thorium in cerium minerals

    USGS Publications Warehouse

    Rose, H.J., Jr.; Murata, K.J.; Carron, M.K.

    1954-01-01

    In a combined chemical-spectrochemical procedure for quantitatively determining rare earth elements in cerium minerals, cerium is determined volumetrically, a total rare earths plus thoria precipitate is separated chemically, the ceria content of the precipitate is raised to 80??0 percent by adding pure ceria, and the resulting mixture is analyzed for lanthanum, praseodymium, neodymium, samarium, gadolinium, yttrium, and thorium spectrochemically by means of the d.c. carbon arc. Spectral lines of singly ionized cerium are used as internal standard lines in the spectrochemical determination which is patterned after Fassel's procedure [1]. Results of testing the method with synthetic mixtures of rare earths and with samples of chemically analyzed cerium minerals show that the coefficient of variation for a quadruplicate determination of any element does not exceed 5??0 (excepting yttrium at concentrations less than 1 percent) and that the method is free of serious systematic error. ?? 1954.

  20. Distribution of rare earth elements in marine sediments from the Strait of Sicily (western Mediterranean Sea): evidence of phosphogypsum waste contamination.

    PubMed

    Tranchida, G; Oliveri, E; Angelone, M; Bellanca, A; Censi, P; D'Elia, M; Neri, R; Placenti, F; Sprovieri, M; Mazzola, S

    2011-01-01

    Concentrations of rare earth elements (REE), Y, Th and Sc were recently determined in marine sediments collected using a box corer along two onshore-offshore transects located in the Strait of Sicily (Mediterranean Sea). The REE+Y were enriched in offshore fine-grained sediments where clay minerals are abundant, whereas the REE+Y contents were lower in onshore coarse-grained sediments with high carbonate fractions. Considering this distribution trend, the onshore sediments in front of the southwestern Sicilian coast represent an anomaly with high REE+Y concentrations (mean value 163.4 ?g g(-1)) associated to high Th concentrations (mean value 7.9 ?g g(-1)). Plot of shale-normalized REE+Y data of these coastal sediments showed Middle REE enrichments relative to Light REE and Heavy REE, manifested by a convexity around Sm-Gd-Eu elements. These anomalies in the fractionation patterns of the coastal sediments were attributed to phosphogypsum-contaminated effluents from an industrial plant, located in the southern Sicilian coast. PMID:21130477

  1. Rare earth and major element geochemistry of Eocene fine-grained sediments in oil shale- and coal-bearing layers of the Meihe Basin, Northeast China

    NASA Astrophysics Data System (ADS)

    Bai, Yueyue; Liu, Zhaojun; Sun, Pingchang; Liu, Rong; Hu, Xiaofeng; Zhao, Hanqing; Xu, Yinbo

    2015-01-01

    The Meihe Basin is a Paleogene pull-apart basin. Long-flame coal, lignite and oil shale are coexisting energy resources deposited in this basin. Ninety-seven samples, including oil shales, coals, brown to gray silt and mudstone, have been collected from the oil shale- and coal-bearing layers to discover the rare earth element geochemistry. The total REE contents of oil shales and coals are 137-256 ?g/g and 64-152 ?g/g respectively. The chondrite-normalized patterns of oil shales and coals show LREE enrichments, HREE deficits, negative Eu anomalies and negligible Ce anomalies. The chemical index of alteration (CIA) as well as some trace elements is often used to reflect the paleoenvironment at the time of deposition. The results show that fine-grained sediments in both layers were deposited in dysoxic to oxic conditions and in a warm and humid climate, and coals were deposited in a warmer and more humid climate than oil shales. Oil shales and coals are both in the early stage of diagenesis and of terrigenous origin. Besides, diagrams of some major, trace and rare earth elements show that the fine-grained sediments of both layers in the Meihe Basin are mainly from the felsic volcanic rocks and granite, and that their source rocks are mostly deposited in the continental inland arc setting. The analysis of major elements shows that Si, Al, K and Ti, in both layers, are found mainly in a mixed clay mineral assemblage and that Si is also found in quartz. Sodium occurs primarily in clay minerals, whereas Ca is found mainly in the organic matter. In the coal-bearing layer, iron is mainly controlled by organic matter rather than detrital minerals. In contrast, in the oil shale-bearing layer, neither detrital minerals nor organic matter exert a control on the iron content. Analyzing the relationship between rare earth elements and major elements shows that REEs in the oil shales and the coals are both of terrigenous origin and are mainly controlled by detrital minerals rather than by organic matter. In both layers, REEs have no relationship with fine-grained phosphates, and during the weathering process, the REEs were not very mobile and were resistant to fractionation.

  2. Rare-earth elements enrichment of Pacific seafloor sediments: the view from volcanic islands of Polynesia

    NASA Astrophysics Data System (ADS)

    Melleton, Jérémie; Tuduri, Johann; Pourret, Olivier; Bailly, Laurent; Gisbert, Thierry

    2014-05-01

    Rare-earth elements (REEs) are key metals for «green» technologies such as energy saving lamps or permanent magnets used in, e.g., wind turbines, hard disk drives, portable phone or electric or hybrid vehicles. Since several years, world demand for these metals is therefore drastically increasing. The quasi-monopolistic position of China, which produces around 95 % of global REEs production, generates risks for the industries that depend on a secure supply of REEs. In response, countries are developing and diversifying their supply sources, with new mining projects located outside China and efforts in the area of REEs recycling. Most of these projects focus on deposits related to carbonatites and alkaline-peralkaline magmatism, which are generally enriched in light REEs (LREEs) compared to the heavy REEs (HREEs)-enriched deposits of the ion-adsorption types, located in southern China. However, a recent study revealed new valuable resources corresponding to seafloor sediments located in the south-eastern and north-central Pacific. The deep-sea mud described by these authors show a higher HREE/LREE ratio than ion-adsorption deposits, a feature which significantly increases their economic interest. The authors suggest mid-ocean ridge hydrothermal activity as an explanation to this anomalous enrichment. However, several contributions have documented considerable REEs enrichment in basalts and peridotitic xenoliths from French Polynesia. Several arguments have been exposed in favour of a supergene origin, with a short migration, suggesting that REEs were collected from weathered basalts. The Tahaa volcanic island (Sous-le-Vent Island, Society Archipelago, French Polynesia) is the first location where such enrichment has been described. New petrographic and mineralogical investigations confirm a supergene mobilization of this abnormal occurrence. REE-bearing minerals (mainly phosphates of the rhabdophane group) are primarily located within basalt vesicles but also in crack that cross-cut the calcite filling the vesicles or the volcanic glass. They are also closely associated with Ni-Mg bearing phyllosilicates, which appear to nucleate from alteration of olivine and clinopyroxenes. Further investigations are done to evidence and confirm an anterior magmatic enrichment. On the basis of these observations, we believe that the anomalous enrichment observed in seafloor sediments could derive from abnormally-rich provinces corresponding to aerial basaltic formations from oceanic islands primarily enriched during weathering processes (Melleton et al., 2014). Melleton et al. (2014). Rare-earth elements enrichment of Pacific sea-floor sediments: the view from volcanic islands of Polynesia. In preparation.

  3. Laboratory simulation of meteoritic noble gases. III - Sorption of neon, argon, krypton, and xenon on carbon - Elemental fractionation

    NASA Technical Reports Server (NTRS)

    Wacker, John F.

    1989-01-01

    The sorption of Ne, Ar, Kr, and Xe was studied in carbon black, acridine carbon, and diamond in an attempt to understand the origin of trapped noble gases in meteorites. The results support a model in which gases are physically adsorbed on interior surfaces formed by a pore labyrinth within amorphous carbons. The data show that: (1) the adsorption/desorption times are controlled by choke points that restrict the movement of noble gas atoms within the pore labyrinth, and (2) the physical adsorption controls the temperature behavior and elemental fractionation patterns.

  4. Provenance of KREEP and the exotic component - Elemental and isotopic studies of grain size fractions in lunar soils

    NASA Technical Reports Server (NTRS)

    Evensen, N. M.; Murthy, V. R.; Coscio, M. R., Jr.

    1974-01-01

    Sieve fraction analyses of lunar soils reveal the presence of a fine-grained exotic component enriched in K, Rb, Sr, Ba, and in radiogenic Sr in all soils. The probable source of this exotic component is the areas of high-surficial radioactivity observed by orbital gamma ray spectrometry, such as those at Fra Mauro and Archimedes. If the exotic component is fine-grained KREEP, the origin and distribution of KREEP fragments in the soils are identified. It is suggested that the exotic component represents trace element enriched material located at some depth in the Imbrium area which was surficially deposited during Imbrium excavation.

  5. Laboratory simulation of meteoritic noble gases. III - Sorption of neon, argon, krypton, and xenon on carbon - Elemental fractionation

    NASA Astrophysics Data System (ADS)

    Wacker, J. F.

    1989-06-01

    The sorption of Ne, Ar, Kr, and Xe was studied in carbon black, acridine carbon, and diamond in an attempt to understand the origin of trapped noble gases in meteorites. The results support a model in which gases are physically adsorbed on interior surfaces formed by a pore labyrinth within amorphous carbons. The data show that: (1) the adsorption/desorption times are controlled by choke points that restrict the movement of noble gas atoms within the pore labyrinth, and (2) the physical adsorption controls the temperature behavior and elemental fractionation patterns.

  6. Health effects and toxicity mechanisms of rare earth elements-Knowledge gaps and research prospects.

    PubMed

    Pagano, Giovanni; Guida, Marco; Tommasi, Franca; Oral, Rahime

    2015-05-01

    In the recent decades, rare earth elements (REE) have undergone a steady spread in several industrial and medical applications, and in agriculture. Relatively scarce information has been acquired to date on REE-associated biological effects, from studies of bioaccumulation and of bioassays on animal, plant and models; a few case reports have focused on human health effects following occupational REE exposures, in the present lack of epidemiological studies of occupationally exposed groups. The literature is mostly confined to reports on few REE, namely cerium and lanthanum, whereas substantial information gaps persist on the health effects of other REE. An established action mechanism in REE-associated health effects relates to modulating oxidative stress, analogous to the recognized redox mechanisms observed for other transition elements. Adverse outcomes of REE exposures include a number of endpoints, such as growth inhibition, cytogenetic effects, and organ-specific toxicity. An apparent controversy regarding REE-associated health effects relates to opposed data pointing to either favorable or adverse effects of REE exposures. Several studies have demonstrated that REE, like a number of other xenobiotics, follow hormetic concentration-related trends, implying stimulatory or protective effects at low levels, then adverse effects at higher concentrations. Another major role for REE-associated effects should be focused on pH-dependent REE speciation and hence toxicity. Few reports have demonstrated that environmental acidification enhances REE toxicity; these data may assume particular relevance in REE-polluted acidic soils and in REE mining areas characterized by concomitant REE and acid pollution. The likely environmental threats arising from REE exposures deserve a new line of research efforts. PMID:25679485

  7. Utilizing rare earth elements as tracers in high TDS reservoir brines in CCS applications

    DOE PAGESBeta

    McLing, Travis; Smith, William; Smith, Robert

    2014-12-31

    In this paper we report the result of research associated with the testing of a procedures necessary for utilizing natural occurring trace elements, specifically the Rare Earth Elements (REE) as geochemical tracers in Carbon Capture and Storage (CCS) applications. Trace elements, particularly REE may be well suited to serve as in situ tracers for monitoring geochemical conditions and the migration of CO?-charged waters within CCS storage systems. We have been conducting studies to determine the efficacy of using REE as a tracer and characterization tool in the laboratory, at a CCS analogue site in Soda Springs, Idaho, and at amore »proposed CCS reservoir at the Rock Springs Uplift, Wyoming. Results from field and laboratory studies have been encouraging and show that REE may be an effective tracer in CCS systems and overlying aquifers. In recent years, a series of studies using REE as a natural groundwater tracer have been conducted successfully at various locations around the globe. Additionally, REE and other trace elements have been successfully used as in situ tracers to describe the evolution of deep sedimentary Basins. Our goal has been to establish naturally occurring REE as a useful monitoring measuring and verification (MMV) tool in CCS research because formation brine chemistry will be particularly sensitive to changes in local equilibrium caused by the addition of large volumes of CO?. Because brine within CCS target formations will have been in chemical equilibrium with the host rocks for millions of years, the addition of large volumes of CO? will cause reactions in the formation that will drive changes to the brine chemistry due to the pH change caused by the formation of carbonic acid. This CO? driven change in formation fluid chemistry will have a major impact on water rock reaction equilibrium in the formation, which will impart a change in the REE fingerprint of the brine that can measured and be used to monitor in situ reservoir conditions. Our research has shown that the REE signature imparted to the formation fluid by the introduction of CO? to the formation, can be measured and tracked as part of an MMV program. Additionally, this REE fingerprint may serve as an ideal tracer for fluid migration, both within the CCS target formation, and should formation fluids migrate into overlying aquifers. However application of REE and other trace elements to CCS system is complicated by the high salt content of the brines contained within the target formations. In the United States by regulation, in order for a geologic reservoir to be considered suitable for carbon storage, it must contain formation brine with total dissolved solids (TDS) > 10,000 ppm, and in most cases formation brines have TDS well in excess of that threshold. The high salinity of these brines creates analytical problems for elemental analysis, including element interference with trace metals in Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) (i.e. element mass overlap due to oxide or plasma phenomenon). Additionally, instruments like the ICP-MS that are sensitive enough to measure trace elements down to the parts per trillion level are quickly oversaturated when water TDS exceeds much more than 1,000 ppm. Normally this problem is dealt with through dilution of the sample, bringing the water chemistry into the instruments working range. However, dilution is not an option when analyzing these formation brines for trace metals, because trace elements, specifically the REE, which occur in aqueous solutions at the parts per trillion levels. Any dilution of the sample would make REE detection impossible. Therefore, the ability to use trace metals as in situ natural tracers in high TDS brines environments requires the development of methods for pre-concentrating trace elements, while reducing the salinity and associated elemental interference such that the brines can be routinely analyzed by standard ICP-MS methods. As part of the Big Sky Carbon Sequestration Project the INL-CAES has developed a rapid, easy to use proces

  8. Utilizing rare earth elements as tracers in high TDS reservoir brines in CCS applications

    SciTech Connect

    McLing, Travis; Smith, William; Smith, Robert

    2014-12-31

    In this paper we report the result of research associated with the testing of a procedures necessary for utilizing natural occurring trace elements, specifically the Rare Earth Elements (REE) as geochemical tracers in Carbon Capture and Storage (CCS) applications. Trace elements, particularly REE may be well suited to serve as in situ tracers for monitoring geochemical conditions and the migration of CO?-charged waters within CCS storage systems. We have been conducting studies to determine the efficacy of using REE as a tracer and characterization tool in the laboratory, at a CCS analogue site in Soda Springs, Idaho, and at a proposed CCS reservoir at the Rock Springs Uplift, Wyoming. Results from field and laboratory studies have been encouraging and show that REE may be an effective tracer in CCS systems and overlying aquifers. In recent years, a series of studies using REE as a natural groundwater tracer have been conducted successfully at various locations around the globe. Additionally, REE and other trace elements have been successfully used as in situ tracers to describe the evolution of deep sedimentary Basins. Our goal has been to establish naturally occurring REE as a useful monitoring measuring and verification (MMV) tool in CCS research because formation brine chemistry will be particularly sensitive to changes in local equilibrium caused by the addition of large volumes of CO?. Because brine within CCS target formations will have been in chemical equilibrium with the host rocks for millions of years, the addition of large volumes of CO? will cause reactions in the formation that will drive changes to the brine chemistry due to the pH change caused by the formation of carbonic acid. This CO? driven change in formation fluid chemistry will have a major impact on water rock reaction equilibrium in the formation, which will impart a change in the REE fingerprint of the brine that can measured and be used to monitor in situ reservoir conditions. Our research has shown that the REE signature imparted to the formation fluid by the introduction of CO? to the formation, can be measured and tracked as part of an MMV program. Additionally, this REE fingerprint may serve as an ideal tracer for fluid migration, both within the CCS target formation, and should formation fluids migrate into overlying aquifers. However application of REE and other trace elements to CCS system is complicated by the high salt content of the brines contained within the target formations. In the United States by regulation, in order for a geologic reservoir to be considered suitable for carbon storage, it must contain formation brine with total dissolved solids (TDS) > 10,000 ppm, and in most cases formation brines have TDS well in excess of that threshold. The high salinity of these brines creates analytical problems for elemental analysis, including element interference with trace metals in Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) (i.e. element mass overlap due to oxide or plasma phenomenon). Additionally, instruments like the ICP-MS that are sensitive enough to measure trace elements down to the parts per trillion level are quickly oversaturated when water TDS exceeds much more than 1,000 ppm. Normally this problem is dealt with through dilution of the sample, bringing the water chemistry into the instruments working range. However, dilution is not an option when analyzing these formation brines for trace metals, because trace elements, specifically the REE, which occur in aqueous solutions at the parts per trillion levels. Any dilution of the sample would make REE detection impossible. Therefore, the ability to use trace metals as in situ natural tracers in high TDS brines environments requires the development of methods for pre-concentrating trace elements, while reducing the salinity and associated elemental interference such that the brines can be routinely analyzed by standard ICP-MS methods. As part of the Big Sky Carbon Sequestration

  9. Platinum group elements and gold in ferromanganese crusts from Afanasiy-Nikitin seamount, equatorial Indian Ocean: Sources and fractionation

    USGS Publications Warehouse

    Banakar, V.K.; Hein, J.R.; Rajani, R.P.; Chodankar, A.R.

    2007-01-01

    The major element relationships in ferromanganese (Fe-Mn) crusts from Afanasiy-Nikitin seamount (ANS), eastern equatorial Indian Ocean, appear to be atypical. High positive correlations (r = 0.99) between Mn/Co and Fe/Co ratios, and lack of correlation of those ratios with Co, Ce, and Ce/Co, indicate that the ANS Fe-Mn crusts are distinct from Pacific seamount Fe-Mn crusts, and reflect region-specific chemical characteristics. The platinum group elements (PGE: Ir, Ru, Rh, Pt, and Pd) and Au in ANS Fe-Mn crusts are derived from seawater and are mainly of terrestrial origin, with a minor cosmogenic component. The Ru/Rh (0.5-2) and Pt/Ru ratios (7-28) are closely comparable to ratios in continental basalts, whereas Pd/Ir ratios exhibit values ( 0.75) correlations between water depth and Mn/Co, Fe/Co, Ce/Co, Co, and the PGEs. Fractionation of the PGE-Au from seawater during colloidal precipitation of the major-oxide phases is indicated by well-defined linear positive correlations (r > 0.8) of Co and Ce with Ir, Ru, Rh, and Pt; Au/Co with Mn/Co; and by weak or no correlations of Pd with water depth, Co-normalized major-element ratios, and with the other PGE (r < 0.5). The strong enrichment of Pt (up to 1 ppm) relative to the other PGE and its positive correlations with Ce and Co demonstrate a common link for the high concentrations of all three elements, which likely involves an oxidation reaction on the Mn-oxide and Fe-oxyhydroxide surfaces. The documented fractionation of PGE-Au and their positive association with redox sensitive Co and Ce may have applications in reconstructing past-ocean redox conditions and water masses.

  10. Concentration of rare earth elements, As, and Th in human brain and brain tumors, determined by neutron activation analysis.

    PubMed

    Zhuang, G; Zhou, Y; Lu, H; Lu, W; Zhou, M; Wang, Y; Tan, M

    1996-01-01

    Toxic elements As and Th, six rare-earth elemental profiles of brain tumor tissues from 16 patients of astrocytomas (grade I-III), and normal human brain tissues of 18 male, age-matched autopsies serving as controls have been studied by radiochemical neutron activation analysis. P-204 [di(2-ethylhexyl) phosphate] extraction chromatography column was used for group separation of rare-earth element (REE) by one step. Compared with the normal brain tissues, the analytical results showed that the concentrations of Th, La, Ce, Gd, and Lu were significantly higher in tumor tissues (P < 0.01 or 0.001). The possible effects of REE on tumor cell were discussed. PMID:8862736

  11. Developing alternative resources of rare earth elements in Europe - EURARE and the red mud challenge

    NASA Astrophysics Data System (ADS)

    Deady, Eimear; Mouchos, Evangelos; Goodenough, Kathryn; Wall, Frances; Williamson, Ben

    2015-04-01

    Rare earth elements (REE) are considered to be highly "critical" by the European Commission [1], owing to the concentration of global supply [2] and their use in a wide range of emerging technologies (e.g. smart phones, electric cars and wind turbines). The main source of REE is the mineral bastnäsite, which is primarily extracted from carbonatites. Alternative resources of REE have been identified in a variety of other environments such as alluvial placers, bauxites and ore tailings. The EURARE project (www.eurare.eu), funded by the European Commission, aims to improve understanding of potential REE resources in Europe with the overall objective of establishing the basis for a European REE industry. As a part of this project, alternative sources of rare earth elements in Europe are being considered. REE have been identified as being particularly enriched in karst-bauxites and hence in the red muds generated as a waste product from the processing of these bauxites to alumina through the Bayer process [3]. Karst-bauxites are widely distributed with deposits known across the Mediterranean and with intermittent exploitation occurring over many decades. REE become concentrated in the bauxite deposits by the bauxitisation process and are retained due to the geochemical barrier created by the limestone bedrock below. This can result in several processes, including the crystallisation of authigenic REE-bearing minerals, the accumulation of residual phases and the adsorption of ions onto clays and other mineral surfaces [4]. Red muds produced from alumina processing represent a potentially important concentration of REE as it has been demonstrated that the REE pass through the alumina extraction process into the waste, and the total REE concentrations are typically enriched by a factor of two compared with the original bauxite ore [5]. Bauxites and red muds from the Parnassus Ghiona region of Greece [6] and the Seydi?ehir-Akseki region of Turkey have been assessed as part of this study. Red muds from these deposits contain on average 900 ppm REE compared with typical values of <100 ppm to ~500 ppm REE in the bauxites. Extraction of REE from red muds has been shown to be feasible [5,7] although it is challenging due to the heterogeneous spatial distribution of REE in the primary bauxite deposits [8], an unclear understanding of the mobility of REE in red mud tailings ponds, and the need for development of appropriate processing methods. However, the resource potential of red muds in Europe is significant with approximately 3.5 Mt of bauxite ore extracted in 2012 [2], resulting in approximately 1.4 Mt of red mud from the production of alumina. In addition a large volume of stockpiled red muds exists from historical processing of bauxites, the total of which is not well constrained. Understanding the REE potential of both bauxites and red muds is integral to an assessment of European REE resources. References [1] European Commission, "Report on critical raw materials for the EU. Report of the Ad hoc Working Group on defining critical raw materials". May 2014. [2] T. Brown, N. Idoine, E. Raycraft, R. Shaw, E. Deady, J. Rippingale, T. Bide, C. Wrighton, J. Rodley, "World Mineral Production 2008-12" British Geological Survey, Keyworth, Nottingham, 2014. [3] Z. Maksimovi? and G. Pantó, "Authigenic rare earth minerals in karst-bauxites and karstic nickel deposits". In: A.P. Jones, F. Wall and C.T. Williams, Rare earth minerals, chemistry, origin and ore deposits, Chapter 10, pp. 257-279, 1996. [4] G. Bárdossy, "Karst Bauxites, Bauxite Deposits on Carbonate Rocks". Elsevier, 444pp, 1982. [5] M. Ochsenkühn-Petropoulou, T. Lyberopoulou, and G. Parissakis, "Direct determination of lanthanides, yttium and scandium in bauxites and red mud from alumina production", Analytica Chimica Acta, vol. 296, no. 3, pp. 305-313, October 1994. [6] É. Deady, E. Mouchos, K. Goodenough, B. Williamson and F. Wall. "Rare Earth Elements in Karst-Bauxites: a Novel Untapped European Resou

  12. Assessment of Bioavailable Concentrations of Germanium and Rare Earth Elements in the Rhizosphere of White Lupin (Lupinus albus L.)

    NASA Astrophysics Data System (ADS)

    Wiche, Oliver; Fischer, Ronny; Moschner, Christin; Székely, Balázs

    2015-04-01

    Concentrations of Germanium (Ge) and Rare Earth Elements in soils are estimated at 1.5 mg kg -1 (Ge), 25 mg kg -1 (La) and 20 mg kg -1 (Nd), which are only roughly smaller than concentrations of Pb and Zn. Germanium and rare earth elements are thus not rare but widely dispersed in soils and therefore up to date, only a few minable deposits are available. An environmental friendly and cost-effective way for Ge and rare earth element production could be phytomining. However, the most challenging part of a phytomining of these elements is to increase bioavailable concentrations of the elements in soils. Recent studies show, that mixed cultures with white lupine or other species with a high potential to mobilize trace metals in their rhizosphere due to an acidification of the soil and release of organic acids in the root zone could be a promising tool for phytomining. Complexation of Ge and rare earth elements by organic acids might play a key role in controlling bioavailability to plants as re-adsorption on soil particles and precipitation is prevented and thus, concentrations in the root zone of white lupine increase. This may also allow the complexes to diffuse along a concentration gradient to the roots of mixed culture growing species leading to enhanced plant uptake. However, to optimize mixed cultures it would be interesting to know to which extend mobilization of trace metals is dependent from chemical speciation of elements in soil due to the interspecific interaction of roots. A method for the identification of complexes of germanium and rare earth elements with organic acids, predominantly citric acid in the rhizosphere of white lupine was developed and successfully tested. The method is based on coupling of liquid chromatography with ICP-MS using a zic-philic column (SeQuant). As a preliminary result, we were able to show that complexes of germanium with citric acid exist in the rhizosphere of white lupin, what may contribute to the bioavailability of this element. These studies have been carried out in the framework of the PhytoGerm project, financed by the Federal Ministry of Education and Research, Germany. The authors are grateful to students and laboratory assistants contributing in the field work and sample preparation.

  13. Effect of paleosol formation on rare earth element signatures in fossil bone

    NASA Astrophysics Data System (ADS)

    Metzger, Christine A.; Terry, Dennis O., Jr.; Grandstaff, David E.

    2004-06-01

    The rare earth element (REE) content of fossil bones was analyzed and compared with the degree of ancient pedogenic development and depositional environments from several locations in the Orellan Scenic Member of the Oligocene Brule Formation in Badlands National Park, South Dakota. Paleosols ranged from weakly developed Entisols to more strongly developed Inceptisols, all typical of fluvial environments and possible paleocatena variation. Paleosols were alkaline and well drained. Sediments with sparse soil features from an oxbow lake system suggest that conditions were too waterlogged and sedimentation rates too rapid for significant pedogenesis. The variance of REE signatures in fossil bones from the paleosol sites was significantly greater than that of fossils from minimally altered sediments of the former oxbow lake. Positive Ce anomalies were associated with low U concentrations and indicate paleoredox conditions. Greater degrees of pedogenesis, regardless of the horizon in which the bone was found, systematically correlated with increased heavy REE enrichment in fossil bones. The fossil-bone REE signatures from the different paleosols and depositional environments were significantly different and distinguishable.

  14. Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.

    PubMed

    Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R

    2015-08-18

    The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets. PMID:26107531

  15. Determination of Rare Earth Elements in Hypersaline Solutions Using Low-Volume, Liquid-Liquid Extraction.

    PubMed

    Noack, Clinton W; Dzombak, David A; Karamalidis, Athanasios K

    2015-08-18

    Complex, hypersaline brines-including those coproduced with oil and gas, rejected from desalination technologies, or used as working fluids for geothermal electricity generation-could contain critical materials such as the rare earth elements (REE) in valuable concentrations. Accurate quantitation of these analytes in complex, aqueous matrices is necessary for evaluation and implementation of systems aimed at recovering those critical materials. However, most analytical methods for measuring trace metals have not been validated for highly saline and/or chemically complex brines. Here we modified and optimized previously published liquid-liquid extraction (LLE) techniques using bis(2-ethylhexyl) phosphate as the extractant in a heptane diluent, and studied its efficacy for REE recovery as a function of three primary variables: background salinity (as NaCl), concentration of a competing species (here Fe), and concentration of dissolved organic carbon (DOC). Results showed that the modified LLE was robust to a range of salinity, Fe, and DOC concentrations studied as well as constant, elevated Ba concentrations. With proper characterization of the natural samples of interest, this method could be deployed for accurate analysis of REE in small volumes of hyper-saline and chemically complex brines. PMID:25920439

  16. Cerium redox cycles and rare earth elements in the Sargasso Sea

    SciTech Connect

    Sholkovitz, E.R.; Schneider, D.L. )

    1991-10-01

    Two profiles of the rare earth elements (REEs) are reported for the upper water column of the Sargasso Sea. The trivalent-only REEs have remarkably constant concentrations in the upper 500m of an April 1989 profile and in the upper 200m of a May 1989 profile. In contrast, Ce concentrations decrease smoothly with increasing depth. In April 1989 Ce decreases from 15.7 pmol/kg at 20 m to 5.1 pmol/kg at 750 m. Cerium, which has Redox transformations in seawater, behaves anomalously with respect to its REE(III) neighbors. While both dissolved Ce and Mn have elevated concentrations in the upper 200m, their vertical gradients are distinctly different. In contrast to Mn, which reaches a minimum dissolved concentration near the zone (150-250 m) of a particulate Mn maximum, Ce is being removed both near this zone and to depths of at least 750m. These new profiles indicate that Ce is involved in an upper ocean redox cycle. This interpretation is consistent with the MOFFETT (1990) incubation tracer experiments on the same May 1989 seawater. He showed that Ce(III) oxidation is biologically mediated, probably light inhibited, increases with depth, and 3-4 times slower than Mn(II) oxidation in the 100-200 m zone. CERoclines provide new information into the fine scale zonation of redox process operating in the upper columns of oligotrophic oceans.

  17. Template polymerization synthesis of hydrogel and silica composite for sorption of some rare earth elements.

    PubMed

    Borai, E H; Hamed, M G; El-kamash, A M; Siyam, T; El-Sayed, G O

    2015-10-15

    New sorbents containing 2-acrylamido 2-methyl propane sulphonic acid monomer onto poly(vinyl pyrilidone) P(VP-AMPS) hydrogel and P(VP-AMPS-SiO2) composite have been synthesized by radiation template polymerization. The effect of absorbed dose rate (kGy), crosslinker concentration and polymer/monomer ratio on the degree of template polymerization of P(VP-AMPS) hydrogel was studied. The degree of polymerization was evaluated by the calculated percent conversion and swelling degree. The maximum capacity of P(VP-AMPS) hydrogel toward Cu(+2) metal ion found to be 91 mg/gm. The polymeric composite P(VP-AMPS-SiO2) has been successfully synthesized. The structure of the prepared hydrogel and composite were confirmed by FTIR, thermal analysis (TGA and DTA) and SEM micrograph. Batch adsorption studies for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(+2) metal ions on the prepared hydrogel and composite were investigated as a function of shaking time, pH and metal ion concentration. The sorption efficiency of the prepared hydrogel and composite toward light rare earth elements (LREEs) are arranged in the order La(3+)>Ce(3+)>Nd(3+)>Eu(3+). The obtained results demonstrated the superior adsorption capacity of the composite over the polymeric hydrogel. The maximum capacity of the polymeric composite was found to be 116, 103, 92, 76, 74 mg/gm for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(2+) metal ions respectively. PMID:26141170

  18. Determination of the rare-earth elements in geological materials by inductively coupled plasma mass spectrometry

    USGS Publications Warehouse

    Lichte, F.E.; Meier, A.L.; Crock, J.G.

    1987-01-01

    A method of analysis of geological materials for the determination of the rare-earth elements using the Inductively coupled plasma mass spectrometric technique (ICP-MS) has been developed. Instrumental parameters and factors affecting analytical results have been first studied and then optimized. Samples are analyzed directly following an acid digestion, without the need for separation or preconcentration with limits of detection of 2-11 ng/g, precision of ?? 2.5% relative standard deviation, and accuracy comparable to inductively coupled plasma emission spectrometry and instrumental neutron activation analysis. A commercially available ICP-MS instrument is used with modifications to the sample introduction system, torch, and sampler orifice to reduce the effects of high salt content of sample solutions prepared from geologic materials. Corrections for isobaric interferences from oxide ions and other diatomic and triatomic ions are made mathematically. Special internal standard procedures are used to compensate for drift in metahmetal oxide ratios and sensitivity. Reference standard values are used to verify the accuracy and utility of the method.

  19. Examination of rare earth element concentration patterns in freshwater fish tissues.

    PubMed

    Mayfield, David B; Fairbrother, Anne

    2015-02-01

    Rare earth elements (REEs or lanthanides) were measured in ten freshwater fish species from a reservoir in Washington State (United States). The REE distribution patterns were examined within fillet and whole body tissues for three size classes. Total concentrations (?REE) ranged from 0.014 to 3.0 mg kg(-1) (dry weight) and averaged 0.243 mg kg(-1) (dry weight). Tissue concentration patterns indicated that REEs accumulated to a greater extent in organs, viscera, and bone compared to muscle (fillet) tissues. Benthic feeding species (exposed to sediments) exhibited greater concentrations of REEs than pelagic omnivorous or piscivorous fish species. Decreasing REE concentrations were found with increasing age, total length or weight for largescale and longnose suckers, smallmouth bass, and walleye. Concentration patterns in this system were consistent with natural conditions without anthropogenic sources of REEs. These data provide additional reference information with regard to the fate and transport of REEs in freshwater fish tissues in a large aquatic system. PMID:25000508

  20. Red Phosphorus: An Earth-Abundant Elemental Photocatalyst for "Green" Bacterial Inactivation under Visible Light.

    PubMed

    Xia, Dehua; Shen, Zhurui; Huang, Guocheng; Wang, Wanjun; Yu, Jimmy C; Wong, Po Keung

    2015-05-19

    Earth-abundant red phosphorus was found to exhibit remarkable efficiency to inactivate Escherichia coli K-12 under the full spectrum of visible light and even sunlight. The reactive oxygen species (•OH, •O2(-), H2O2), which were measured and identified to derive mainly from photogenerated electrons in the conduction band using fluorescent probes and scavengers, collectively contributed to the good performance of red phosphorus. Especially, the inactivated-membrane function enzymes were found to be associated with great loss of respiratory and ATP synthesis activity, the kinetics of which paralleled cell death and occurred much earlier than those of cytoplasmic proteins and chromosomal DNA. This indicated that the cell membrane was a vital first target for reactive oxygen species oxidation. The increased permeability of the cell membrane consequently accelerated intracellular protein carboxylation and DNA degradation to cause definite bacterial death. Microscopic analyses further confirmed the cell destruction process starting with the cell envelope and extending to the intracellular components. The red phosphorus still maintained good performance even after recycling through five reaction cycles. This work offers new insight into the exploration and use of an elemental photocatalyst for "green" environmental applications. PMID:25894494

  1. Gupta potential for rare earth elements of the fcc phase: lanthanum and cerium

    NASA Astrophysics Data System (ADS)

    Fu, Jie; Zhao, Jijun

    2013-09-01

    The potential parameters for a Gupta-type many-body potential are fitted for the first two rare earth elements, La and Ce. The experimental cohesive energies, lattice parameters and elastic constants of ?-La and ?-Ce solids of the face-centered cubic (fcc) phase are well reproduced. The theoretical P-V curves, sound velocities and Debye temperatures of ?-La and ?-Ce solids are in reasonable agreement with experimental data. The vacancy formation energies and surface energies are also predicted. In particular, the phonon dispersion relationship and vibrational frequencies at high symmetric points within the first Brillouin zone from our potential are consistent with experimental ones. Molecular dynamics simulation are performed to determine the melting temperature of La and Ce solids as well as the radial distribution function of liquid La, which are also in line with experimental data. All these agreements indicate the validity of the current set of potential parameters. Thus, the Gupta potential developed here would be useful in future simulation of La, Ce solids and their alloys.

  2. Remediation of Rare Earth Element Pollutants by Sorption Process Using Organic Natural Sorbents

    PubMed Central

    Butnariu, Monica; Negrea, Petru; Lupa, Lavinia; Ciopec, Mihaela; Negrea, Adina; Pentea, Marius; Sarac, Ionut; Samfira, Ionel

    2015-01-01

    The effects of the sorption of environmental applications by various source materials of natural organic matter, i.e., bone powder, was examined. Sorption capacities and subsequent rare earth element retention characteristics of all metals tested were markedly increased by ionic task-specific. In this study, the abilities of three models’ isotherms widely were used for the equilibrium sorption data: Langmuir, Freundlich and Redlich-Peterson. For all studied metal ions the maximum adsorption capacity is close to those experimentally determined. The characteristic parameters for each isotherm and related coefficients of determination have been determined. The experimental data achieved excellent fits within the following isotherms in the order: Langmuir > Redlich-Peterson > Freundlich, based on their coefficient of determination values. The bone powder has developed higher adsorption performance in the removal process of Nd(III), Eu(III), La(III) from aqueous solutions than in the case of the removal process of Cs(I), Sr(II) and Tl(I) from aqueous solutions. The described relationships provide direct experimental evidence that the sorption-desorption properties of bone powder are closely related to their degree of the type of the metal. The results suggest a potential for obtaining efficient and cost-effective engineered natural organic sorbents for environmental applications. PMID:26378553

  3. Composition and evolution of the eucrite parent body - Evidence from rare earth elements. [extraterrestrial basaltic melts

    NASA Technical Reports Server (NTRS)

    Consolmagno, G. J.; Drake, M. J.

    1977-01-01

    Quantitative modeling of the evolution of rare earth element (REE) abundances in the eucrites, which are plagioclase-pigeonite basalt achondrites, indicates that the main group of eucrites (e.g., Juvinas) might have been produced by approximately 10% equilibrium partial melting of a single type of source region with initial REE abundances which were chondritic relative and absolute. Since the age of the eucrites is about equal to that of the solar system, extensive chemical differentiation of the eucrite parent body prior to the formation of eucrites seems unlikely. If homogeneous accretion is assumed, the bulk composition of the eucrite parent body can be estimated; two estimates are provided, representing different hypotheses as to the ratio of metal to olivine in the parent body. Since a large number of differentiated olivine meteorites, which would represent material from the interior of the parent body, have not been detected, the eucrite parent body is thought to be intact. It is suggested that the asteroid 4 Vesta is the eucrite parent body.

  4. Remediation of Rare Earth Element Pollutants by Sorption Process Using Organic Natural Sorbents.

    PubMed

    Butnariu, Monica; Negrea, Petru; Lupa, Lavinia; Ciopec, Mihaela; Negrea, Adina; Pentea, Marius; Sarac, Ionut; Samfira, Ionel

    2015-09-01

    The effects of the sorption of environmental applications by various source materials of natural organic matter, i.e., bone powder, was examined. Sorption capacities and subsequent rare earth element retention characteristics of all metals tested were markedly increased by ionic task-specific. In this study, the abilities of three models' isotherms widely were used for the equilibrium sorption data: Langmuir, Freundlich and Redlich-Peterson. For all studied metal ions the maximum adsorption capacity is close to those experimentally determined. The characteristic parameters for each isotherm and related coefficients of determination have been determined. The experimental data achieved excellent fits within the following isotherms in the order: Langmuir > Redlich-Peterson > Freundlich, based on their coefficient of determination values. The bone powder has developed higher adsorption performance in the removal process of Nd(III), Eu(III), La(III) from aqueous solutions than in the case of the removal process of Cs(I), Sr(II) and Tl(I) from aqueous solutions. The described relationships provide direct experimental evidence that the sorption-desorption properties of bone powder are closely related to their degree of the type of the metal. The results suggest a potential for obtaining efficient and cost-effective engineered natural organic sorbents for environmental applications. PMID:26378553

  5. New Fission Fragment Distributions and r-Process Origin of the Rare-Earth Elements

    NASA Astrophysics Data System (ADS)

    Goriely, S.; Sida, J.-L.; Lemaître, J.-F.; Panebianco, S.; Dubray, N.; Hilaire, S.; Bauswein, A.; Janka, H.-T.

    2013-12-01

    Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process elements with nuclear mass numbers A?140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular, the fission fragment yields determine the creation of 110?A?170 nuclei. Here, we apply a new scission-point model, called SPY, to derive the fission fragment distribution (FFD) of all relevant neutron-rich, fissioning nuclei. The model predicts a doubly asymmetric FFD in the abundant A?278 mass region that is responsible for the final recycling of the fissioning material. Using ejecta conditions based on relativistic NS merger calculations, we show that this specific FFD leads to a production of the A?165 rare-earth peak that is nicely compatible with the abundance patterns in the Sun and metal-poor stars. This new finding further strengthens the case of NS mergers as possible dominant origin of r nuclei with A?140.

  6. New fission fragment distributions and r-process origin of the rare-earth elements.

    PubMed

    Goriely, S; Sida, J-L; Lemaître, J-F; Panebianco, S; Dubray, N; Hilaire, S; Bauswein, A; Janka, H-T

    2013-12-13

    Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process elements with nuclear mass numbers A?140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular, the fission fragment yields determine the creation of 110?A?170 nuclei. Here, we apply a new scission-point model, called SPY, to derive the fission fragment distribution (FFD) of all relevant neutron-rich, fissioning nuclei. The model predicts a doubly asymmetric FFD in the abundant A?278 mass region that is responsible for the final recycling of the fissioning material. Using ejecta conditions based on relativistic NS merger calculations, we show that this specific FFD leads to a production of the A?165 rare-earth peak that is nicely compatible with the abundance patterns in the Sun and metal-poor stars. This new finding further strengthens the case of NS mergers as possible dominant origin of r nuclei with A?140. PMID:24483647

  7. Rare earth element distribution in some hydrothermal minerals: evidence for crystallographic control

    USGS Publications Warehouse

    Morgan, J.W.; Wandless, G.A.

    1980-01-01

    Rare earth element (REE) abundances were measured by neutron activation analysis in anhydrite (CaSO4), barite (BaSO4), siderite (FeCO3) and galena (PbS). A simple crystal-chemical model qualitatively describes the relative affinities for REE substitution in anhydrite, barite, and siderite. When normalized to 'crustal' abundances (as an approximation to the hydrothermal fluid REE pattern), log REE abundance is a surprisingly linear function of (ionic radius of major cation-ionic radius of REE)2 for the three hydrothermal minerals, individually and collectively. An important exception, however, is Eu, which is anomalously enriched in barite and depleted in siderite relative to REE of neighboring atomic number and trivalent ionic radius. In principle, REE analyses of suitable pairs of co-existing hydrothermal minerals, combined with appropriate experimental data, could yield both the REE content and the temperature of the parental hydrothermal fluid. The REE have only very weak chalcophilic tendencies, and this is reflected by the very low abundances in galena-La, 0.6 ppb; Sm, 0.06 ppb; the remainder are below detection limits. ?? 1980.

  8. Rare earth element geochemistry of massive sulfides-sulfates and gossans on the Southern Explorer Ridge

    SciTech Connect

    Barrett, T.J. ); Jarvis, I. ); Jarvis, K.E. )

    1990-07-01

    Massive sulfide-sulfate deposits on the Southern Explorer Ridge were analyzed for 14 rare earth elements (REE) by a modified inductively coupled plasma-mass spectrometric technique that included a correction for high Ba content. Bulk samples of finely intermixed sulfides, sulfate, and amorphous silica contain {Sigma}REE concentrations of {le} 6 ppm. REE patterns range from (1) strongly enriched in light REE with positive Eu anomalies, to (2) relatively flat with positive Eu anomalies and slightly negative Ce anomalies, to (3) slightly enriched in light REE with moderately negative Ce anomalies. Pattern 1 is similar to that of 300-350 C solutions discharging at vents on the East Pacific Rise and the Mid-Atlantic Ridge, whereas pattern 3 resembles REE distributions in normal oceanic bottom waters. The sulfide-sulfate patterns are interpreted to result from variable mixtures of hydrothermal and normal seawater. Barite in gossans capping the mounds has an REE pattern almost identical to patterns of high-temperature vent solutions. Hydrothermal barite has lower REE contents and a different REE pattern relative to hydrogenous barite formed slowly on the sea floor.

  9. Rare earth elements in the water column of Lake Vanda, McMurdo Dry Valleys, Antarctica

    NASA Astrophysics Data System (ADS)

    De Carlo, Eric Heinen; Green, William J.

    2002-04-01

    We present data on the composition of water from Lake Vanda, Antarctica. Vanda and other lakes in the McMurdo Dry Valleys of Antarctica are characterized by closed basins, permanent ice covers, and deep saline waters. The meromictic lakes provide model systems for the study of trace metal cycling owing to their pristine nature and the relative simplicity of their biogeochemical systems. Lake Vanda, in the Wright Valley, is supplied by a single input, the Onyx River, and has no output. Water input to the lake is balanced by sublimation of the nearly permanent ice cap that is broken only near the shoreline during the austral summer. The water column is characterized by an inverse thermal stratification of anoxic warm hypersaline water underlying cold oxic freshwater. Water collected under trace-element clean conditions was analyzed for its dissolved and total rare earth element (REE) concentrations by inductively coupled plasma mass spectrometry. Depth profiles are characterized by low dissolved REE concentrations (La, Ce, <15 pM) in surface waters that increase slightly (La, 70 pM; Ce, 20 pM) with increasing depth to ˜55 m, the limit of the fresh oxic waters. Below this depth, a sharp increase in the concentrations of strictly trivalent REE (e.g., La, 5 nM) is observed, and a submaximum in redox sensitive Ce (2.6 nM) is found at 60- to 62-m depth. At a slightly deeper depth, a sharper Ce maximum is observed with concentrations exceeding 11 nM at a 67-m depth, immediately above the anoxic zone. The aquatic concentrations of REE reported here are ˜50-fold higher than previously reported for marine oxic/anoxic boundaries and are, to our knowledge, the highest ever observed at natural oxic/anoxic interfaces. REE maxima occur within stable and warm saline waters. All REE concentrations decrease sharply in the sulfidic bottom waters. The redox-cline in Lake Vanda is dominated by diffusional processes and vertical transport of dissolved species driven by concentration gradients. Furthermore, because the ultraoligotrophic nature of the lake limits the potential for organic phases to act as metal carriers, metal oxide coatings and sulfide phases appear to largely govern the distribution of trace elements. We discuss REE cycling in relation to the roles of redox reactions and competitive scavenging onto Mn- and Fe-oxides coatings on clay sized particles in the upper oxic water column and their release by reductive dissolution near the anoxic/oxic interface.

  10. [Indirect determination of rare earth elements in Chinese herbal medicines by hydride generation-atomic fluorescence spectrometry].

    PubMed

    Zeng, Chao; Lu, Jian-Ping; Xue, Min-Hua; Tan, Fang-Wei; Wu, Xiao-Yan

    2014-07-01

    Based on their similarity in chemical properties, rare earth elements were able to form stable coordinated compounds with arsenazo III which were extractable into butanol in the presence of diphenylguanidine. The butanol was removed under reduced pressure distillation; the residue was dissolved with diluted hydrochloric acid. As was released with the assistance of KMnO4 and determined by hydrogen generation-atomic fluorescence spectrometry in terms of rare earth elements. When cesium sulfate worked as standard solution, extraction conditions, KMnO4 amount, distillation temperature, arsenazo III amount, interfering ions, etc were optimized. The accuracy and precision of the method were validated using national standard certified materials, showing a good agreement. Under optimum condition, the linear relationship located in 0.2-25 microg x mL(-1) and detection limit was 0.44 microg x mL(-1). After the herbal samples were digested with nitric acid and hydrogen peroxide, the rare earth elements were determined by this method, showing satisfactory results with relative standard deviation of 1.3%-2.5%, and recoveries of 94.4%-106.0%. The method showed the merits of convenience and rapidness, simple instrumentation and high accuracy. With the rare earths enriched into organic phase, the separation of analytes from matrix was accomplished, which eliminated the interference. With the residue dissolved by diluted hydrochloric acid after the solvent was removed, aqueous sample introduction eliminated the impact of organic phase on the tubing connected to pneumatic pump. PMID:25269316

  11. Toxicologically important trace elements and organic compounds investigated in size-fractionated urban particulate matter collected near the Prague highway.

    PubMed

    Sysalová, Ji?ina; Sýkorová, Ivana; Havelcová, Martina; Száková, Ji?ina; Trejtnarová, Hana; Kotlík, Bohumil

    2012-10-15

    Urban particulate matter was collected in the most exposed area of Prague, near a busy highway, in order to provide petrographic and chemical characterization useful for health impact assessment in that locality or other applications. Samples were collected from filters of the air conditioning system in two years, 2009 and 2010, and sieved into four grain-size fractions: 0.507-0.119 mm, 0.119-0.063 mm, <0.063 mm and sub-fraction <0.025 mm. Methods of destructive and non-destructive analyses were used for the determination of total analyte (As, Cd, Cr, Mn, Ni, Pb, Zn) contents. Labile forms of some toxicologically important analytes were tested in 2 M HNO(3) extracted solutions. A composition of inorganic and carbonaceous particles of natural and anthropogenic origin and their morphology were studied by optical and electron microscopy. Organic solvent extracts of the samples were analyzed using gas chromatography to compare the organic compound distribution in fractions. Only slight differences between 2009 and 2010 years are visible. The relatively high extractable part of most investigated elements confirms mobility and potential availability to organisms. The changes can be recognized in the petrographic and organic composition in samples from both years, which were likely the result of various inputs of source materials. Specific organic marker compounds indicate contribution from fossil fuels, plant materials and bacteria. PMID:22940040

  12. Rare earth element mineralogy, geochemistry, and preliminary resource assessment of the Khanneshin carbonatite complex, Helmand Province, Afghanistan

    USGS Publications Warehouse

    Tucker, Robert D.; Belkin, Harvey E.; Schulz, Klaus J.; Peters, Stephen G.; Buttleman, Kim P.

    2011-01-01

    There is increased concern about the future availability of rare earth elements (REE) because of China's dominance as the supplier of more than 95 percent of world REE output, their decision to restrict exports of rare earth products, and the rapid increase in world-wide consumption of rare earth product. As a result, countries such as the United States, Japan, and member nations of the European Union face a future of tight supplies and high prices for rare earth products unless other sources of REE are found and developed (Long and others, 2010; U.S. Geological Survey, 2011, p. 128-129, 184-185). We report and describe a significant new deposit of light rare earth elements (LREE), estimated at 1 Mt, within the Khanneshin carbonatite complex of south Afghanistan. The potential resource is located in a remote and rugged part of the igneous complex in a region previously identified by Soviet geologists in the 1970s. This report reviews the geologic setting of LREE deposit, presents new geochemical data documenting the grade of LREE mineralization, briefly describes the mineralogy and mineralogical associations of the deposit, and presents a preliminary estimate of LREE resources based on our current understanding of the geology.

  13. Rare earth elements in the sedimentary cycle - A pilot study of the first leg

    NASA Technical Reports Server (NTRS)

    Basu, A.; Blanchard, D. P.; Brannon, J. C.

    1982-01-01

    The effects of source rock composition and climate on the natural abundances of rare elements (REE) in the first leg of the sedimentary cycle are evaluated using a study with Holocene fluvia sands. The medium grained sand fraction of samples collected from first order streams exclusively draining granitic plutons in Montana (semi-arid), Georgia (humid), and South Carolina (humid) are analyzed. It is found that the REE distribution patterns (but not the total absolute abundances) of the daughter sands are very similar, despite compositional differences between parent plutons. Averages of the three areas are determined to have a La/Lu ratio of about 103, showing a depletion of heavy REE with respect to an average granite (La/Lu = 79) or the composition of North American Shales (La/Lu = 55). However, the Eu/Sm ratio in sands from these areas is about 0.22, which is very close to this ratio in North American Shales (0.21), although the overall REE distribution of these sands is not similar to that of the North American Shales in any way. It is concluded that the major rock type, but neither its minor subdivisions nor the climate, controls the REE distribution patterns in first cycle daughter sands, although the total and the parent rock-normalized abundances of REE in sands from humid areas are much lower than those in sands from arid areas.

  14. Study of leachability and fractional alteration of arsenic and co-existing elements in stabilized contaminated sludge using a flow-through extraction system.

    PubMed

    Buanuam, Janya; Wennrich, Rainer

    2011-06-01

    This study investigates the stabilization of As in the contaminated sludge after treatment with MnO(2) or Ca(OH)(2), and the influence of the stabilizing materials on the leachability of the co-existing elements Pb and Zn. By exploiting a continuous-flow assembly facilitating a modified Wenzel's sequential extraction scheme (designed for the fractionation of arsenic), it is possible to ascertain the leachability, mobility and fractional alteration of these elements under stimulated natural (flow-through) leaching conditions. The fractionation data show that more than 80% of As, Pb and Zn in the untreated sludge are bound in the amorphous Fe oxides fraction and residual fraction. The addition of MnO(2) has only an insignificant effect on As fractional transformation, while Ca(OH)(2) caused an increase in As mobility. For Pb, the decrease in leachability was clearly visible. The extractable Pb was reduced by 18% and 40% in stabilized MnO(2) and Ca(OH)(2) sludge samples, respectively. Unlike that of Pb, the mobility of Zn was not affected by the additives used. Their fractional distribution patterns before and after the stabilization process remained the same. The ability to produce detailed leaching profiles for As and other elements (Pb, Zn, Ca, Mn and Fe) meant that elemental associations in individual fractions could be examined. From the MnO(2)-treated sludge, the coincidence of the As, Pb, Zn, Fe, and Mn peaks seems to indicate a close association of these elements in the Fe-oxides-bound fraction. Furthermore, the leaching profiles may be used as evidence of a strong affinity between these elements and added MnO(2). PMID:21503335

  15. Release Fractions from Multi-Element Spent Fuel Casks Resulting from HEDD Attack

    SciTech Connect

    Luna, R. E.

    2006-07-01

    This paper provides a simple model for estimating the release of respirable aerosols resulting from an attack on a spent fuel cask using a high energy density device (HEDD). Two primary experiments have provided data on potential releases from spent fuel casks under HEDD attack. Sandia National Laboratories (SNL) conducted the first in the early 1980's and the second was sponsored by Gessellshaft fur Anlagen- and Reaktorsicherheit (GRS) in Germany and conducted in France in 1994. Both used surrogate spent fuel assemblies in real casks. The SNL experiments used un-pressurized fuel pin assemblies in a single element cask while the GRS tests used pressurized fuel pin assemblies in a 9-element cask. Data from the two test programs is reasonably consistent, given the differences in the experiments, but the use of the test data for prediction of releases resulting from HEDD attack requires a method for accounting for the effects of pin pressurization release and the ratio of pin plenum gas release to cask free volume (VR). To account for the effects of VR and to link the two data sources, a simple model has been developed that uses both the SNL data and the GRS data as well as recent test data on aerosols produced in experiments with single pellets subjected to HEDD effects conducted under the aegis of the International Consortium's Working Group on Sabotage of Transport and Storage Casks (WGSTSC). (authors)

  16. Experimental investigations of trace element fractionation in iron meteorites. I - Early results

    NASA Technical Reports Server (NTRS)

    Bild, R. W.; Drake, M. J.

    1978-01-01

    Experimental procedures for measuring trace element partitioning among metal and sulfide and silicate phases are described, and solid metal/liquid metal partition coefficients for minor and trace elements in the Fe-Ni system at 5 to 14% Ni are reported. The bulk compositions desired are homogenized at superliquidus temperature for 15-24 hours, held at a temperature in the solid/liquid two phase region for about 24 hours, and quenched to freeze in the equilibrium compositions. Run products are analyzed by electron microprobe. With the exception of Cr, all preliminary partition coefficients obtained are in the same sense as values derived from iron meteorites. The partition coefficients for Cr in solid metal/liquid metal and metal/troilite systems suggest that IIIAB and main group pallasites equilibrated with 9-22% troilite. A second method which makes it possible to place upper and lower limits on the partition coefficient by holding part of the sample at subliquidus and part at superliquidus temperatures, yielded significantly different results for the two metals tested (Au and Pt) from those obtained by the first method, demonstrating the importance of a close approach to equilibrium before using experimentally-determined partition coefficients to test empirical differentiation models for iron meteorites.

  17. Rare-earth elements and Nd and Pb isotopes as source indicators for Labrador Sea clay-size sediments during Heinrich event 2

    USGS Publications Warehouse

    Benson, L.; Barber, David; Andrews, John T.; Taylor, H.; Lamothe, P.

    2003-01-01

    Elemental abundances and Nd and Pb isotope ratios were determined on samples from the carbonate-free, clay-size fractions of sediments from intervals above, within, and below Heinrich event 2 (H-2) in core HU87-9 from the Northwest Labrador Sea slope. In HU87-9, rare-earth element (REE) distributions and elemental concentrations within the H-2 event are distinct from those outside this event, ??Nd(0) and 206Pb/204Pb data also indicate different values for sediments deposited within and outside the H-2 event. Comparisons of REE patterns from the H-2 interval with those from bedrock units in Baffin Island, northern Quebec, and Labrador indicate that the Lake Harbour Group (LHG), which crops out on the north side of the Hudson Strait, is the most probable bedrock source of the clay-size fraction found within the H-2 interval in HU87-9. The Tasiuyak Gneiss (TG) and Lac Lomier Complex (LLC) have REE patterns (including a negative Eu anomaly) similar to those found in H-2 sediments; however, the La/Yb ratios of these units are smaller than those associated with H-2 sediments. The Nd and Pb isotope data support and complement REE-based interpretations of provenance; i.e., the Nd-Pb signatures of sediments deposited at the HU87-9 site during the H-2 event are similar to Nd-Pb signatures obtained on diamicts from the western end of Hudson Strait. Published by Elsevier Science Ltd.

  18. Genesis of the central zone of the Nolans Bore rare earth element deposit, Northern Territory, Australia

    NASA Astrophysics Data System (ADS)

    Schoneveld, Louise; Spandler, Carl; Hussey, Kelvin

    2015-08-01

    The Nolans Bore rare earth element (REE) deposit consists of a network of fluorapatite-bearing veins and breccias hosted within Proterozoic granulites of the Reynolds Range, Central Australia. Mineralisation is divided into three zones (north, central, and south-east), with the north and south-east zones consisting of massive REE-bearing fluorapatite veins, with minor brecciation and carbonate infill. The central zone is distinctively different in mineralogy and structure; it features extensive brecciation, a high allanite content, and a large, epidote-rich enveloping alteration zone. The central zone is a reworking of the original solid apatite veins that formed during the Chewings Orogeny at ca. 1525 Ma. These original apatite veins are thought to derive from phosphate-rich magmatic-hydrothermal fluid exsolved from as-yet unrecognised alkaline magmatic bodies at depth. We define four ore breccia types (BX1-4) in the central zone on the basis of detailed petrological and geochemical analysis of drillcore and thin sections. BX1 ore comprises fluorapatite with minor crackle brecciation with carbonate infill and resembles ore of the north and south-east zones. Breccia types BX2, BX3, and BX4 represent progressive stages of ore brecciation and development of calc-silicate mineral (amphibole, epidote, allanite, calcite) infill. Comparison of bulk ore sample geochemistry between breccia types indicates that REEs were not mobilised more than a few centimetres during hydrothermal alteration and brecciation. Instead, most of the REEs were partitioned from the original REE fluorapatite into newly formed allanite, REE-poor fluorapatite and minor REE carbonate in the breccias. Negative europium (Eu) anomalies in the breccia minerals are accounted for by a large positive Eu anomaly in epidote from the alteration zones surrounding the ore breccias. This observation provides a direct link between ore recrystallisation and brecciation, and the formation of the alteration halo in the surrounding host rocks. Where allanite and fluorapatite are texturally related, the fluorapatite is relatively depleted in the light rare earth elements (LREEs), whereas allanite is relatively LREE enriched, suggesting co-crystallisation. We tentatively date the BX1 ore stage to 1440 ± 80 Ma based on U-Pb dating of thorianite. Sm-Nd isotope isochrons derived from in situ isotope analysis of cognate apatite and allanite date the BX2 and BX3 events to ca. 400 Ma, while U-Pb dating of late-stage monazite from the BX4 ore stage returned an age of ca. 350 Ma. Therefore, formation of the central zone at Nolans Bore involved multiple alteration/brecciation events that collectively span over 1 billion years in duration. We suggest that the BX1-type veins and breccias were formed from REE-rich, saline (F- and Cl-bearing) fluids that infiltrated the granulite-grade host rocks in association with either shear activation events of the Redbank Shear Zone (1500-1400 Ma) or intrusion of late-stage pegmatites of the Mt Boothby area. BX2, BX3, and BX4 events record deformation and hydrothermal alteration associated with the Alice Springs Orogeny (400-350 Ma). These hydrothermal events occurred at temperatures of 450 to ~600 °C, due to inflow of highly acidic hydrous fluids derived from a magmatic source, or from mixing of meteoric and metamorphic fluids. Our data testify to the long and complex geological history of not only the Nolans Bore REE deposit, but also of the rocks of the eastern Reynolds Range, and demonstrate the great utility of using hydrothermally derived REE minerals to trace the timing of crustal deformation events and source of associated hydrothermal fluids.

  19. The Use of Lead Isotope and Rare Earth Element Geochemistry for Forensic Geographic Provenancing

    NASA Astrophysics Data System (ADS)

    Carey, A.; Darrah, T.; Harrold, Z.; Prutsman-Pfeiffer, J.; Poreda, R.

    2008-12-01

    Lead isotope and rare earth element composition of modern human bones are analyzed to explore their utility for geographical provenancing. DNA analysis is the standard for identification of individuals. DNA analysis requires a DNA match for comparison. Thus, DNA analysis is of limited use in cases involving unknown remains. Trace elements are incorporated into bones and teeth during biomineralization, recording the characteristics of an individual's geochemical environment. Teeth form during adolescence, recording the geochemical environment of an individual's youth. Bones remodel throughout an individual's lifetime. Bones consist of two types of bone tissue (cortical and trabecular) that remodel at different rates, recording the geochemical environment at the time of biomineralization. Cortical bone tissue, forming the outer surface of bones, is dense, hard tissue that remodels in 25-30 yrs. Conversely, trabecular bone tissue, the inner cavity of bones, is low density, porous and remodels in 2-5 years. Thus, analyzing teeth and both bone tissues allows for the development of a geographical time line capable of tracking immigration patterns through time instead of only an individual's youth. Geochemical isotopic techniques (Sr, O, C, N) have been used for geographical provenancing in physical anthropology. The isotopic values of Sr, C, O, N are predominantly a function of soil compositions in areas where food is grown or water is consumed. Application of these provenancing techniques has become difficult as an individual's diet may reflect the isotopic composition of foods obtained at the local grocer as opposed to local soil compositions. Thus, we explore the use of REEs and Pb isotopes for geographical provenancing. Pb and REEs are likely more reliable indicators of modern geographical location as their composition are high in bio-available sources such as local soils, atmospheric aerosols, and dust as opposed to Sr, C, O, N that are controlled by food and drinking water. Lead isotope and REE analysis of trabecular and cortical bone tissue of 60 femoral heads resected during hip replacement surgery at the Univ. of Roch. Medical Center were analyzed by a combination of TIMS and ICP-MS. Results show that Pb compositions are consistent with local soil with variable inputs from known environmental sources. Several samples demonstrate inputs from known environmental sources (e.g. Mississippi Valley ore) that was used in paint, solder, and US gasoline. Additionally, results suggest bioincorporation of Pb with isotopic composition consistent with that observed for Canadian gasoline aerosols. Immigrants included in the study show Pb compositions distinctly different than local residents.

  20. Geochemical characteristics of rare earth elements in soil of the Ditru Massif, Eastern Carpathians, Romania

    NASA Astrophysics Data System (ADS)

    Ion, Adriana

    2013-04-01

    The present paper describes the level of rare earth elements in soils developed from Ditr?u massif area for evaluating of the background of these elements and accurate assessment of environmental impact. Also this paper contributed to understanding the important role of parent rocks in pedogenic processes. The Ditr?u Alkaline Massif represent an intrusion body with a internal zonal structure, which was emplaced into pre-Alpine metamorphic rocks of the Bucovinian nappe complex close the Neogene - Quaternary volcanic arc of the Calimani-Guurghiu- Harghita Mountain chain. The center of massif was formed by nepheline syenite, which is surrounded by syenite and monazonite. North-western and north-eastern marginal sectors are composed of hornblende gabbro/hornblendite, alkali diorite, monzodiorite, monzosyenites and alkali granite. Small discrete ultramafic bodies (kaersutite-bearing peridotite, olivine, pyroxenite and hornblendite) and alkali gabbros occur in the Jolotca area. All this rocks are cut by late-stage dykes with a large variety of composition including tinguaite, phonolite, nepheline syenite, microsyenite, and aplite. The types of soils predominant in this zone are lithosoils. These soils are shallow developed, have low content in organic matter and reflects mineralogical and geochemical composition of the bedrock. The soil samples were collected from 70 location for all type of representative rocks (approximately 10 soil sampling points for each type of rock). The samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The pH values of these samples varied from 3.6 to 7.3, in general, the soils from massif area are acid or weakly acidic. The pH controls the abundance of REE in soil, the concentration of REE increases with decreasing pH values. In soil samples analyzed the contents of REE follow the order: Ce > La > Nd > Pr > Sm > Eu > Gd > Dy > Yb > Er > Tb > Ho >Tm. ? REE varied from 52.59 ?g g-1 to 579.2 ?g g-1 , the average is 273.14 ?g g-1. The chemical analysis of soil showed an enrichment in LREE (from La to Eu) and a depletion in HREE (from Gd to Lu). Relatively high levels of LREE concentration in soil are genetically associated with REE mineralization. The soil samples developed on the syenite and nephelin syenite are enriched in HREE. The REE chondrite - normalized plots showed for most soils in the sampling area strongly negative anomalies for cerium and europium, positive anomalies for gadolinium and dysprosium. The distribution of REE in soil is given and controlled by the presence of primary minerals (potasic and plagioclase feldspars) and accessory minerals (zircon, monazite, titanite, allanite, apatite, xenotime, thorite, bastnäsite) in bedrock.

  1. APPLICATION OF MECHANICAL ACTIVATION TO PRODUCTION OF PYROCHLORE CERAMIC CONTAINING SIMULATED RARE-EARTH ACTINIDE FRACTION OF HLW

    SciTech Connect

    Stefanovsky, S.V.; Kirjanova, O.I.; Chizhevskaya, S.V.; Yudintsev, S.V.; Nikonov, B.S.

    2003-02-27

    Samples of zirconate pyrochlore ceramic (REE)2(Zr,U)2O7 (REE = La-Gd) containing simulated REE-An fraction of HLW were synthesized by two routes: (1) conventional cold compaction of oxide mixtures in pellets under pressure of 200 MPa and sintering of the pellets at 1550 C for 24 hours; and (2) using preliminary mechanical activation of oxide powders in a linear inductive rotator (LIV-0.5E) and a planetary mill - activator with hydrostatic yokes (AGO-2U) for 5 or 10 min. All the samples sintered at 1550 C were monolithic and dense with high mechanical integrity. As follows from X-ray diffraction (XRD) data, the ceramic sample produced without mechanical activation is composed of pyrochlore as major phase but contains also minor unreacted oxides. The samples prepared from pre-activated mixtures are composed of the pyrochlore structure phase only. Scanning electron microscopy (SEM) data also show higher structural and compositional homogeneity of the samples prepared from mechanically activated batches. The samples produced from oxide mixtures mechanically activated in the LIV for 10 min were slightly contaminated with iron resulting in formation of minor perovskite structure phase not detected by XRD but seen on SEM-images of the samples. Comparison of the samples prepared from non-activated and activated batches showed higher density, lower open porosity, water uptake, and elemental leaching for the samples fabricated from mechanically activated oxide mixtures.

  2. Carbonatite: A Geophysical investigation of a rare earth element terrane, eastern Mojave Desert, California

    NASA Astrophysics Data System (ADS)

    Denton, K. M.; Ponce, D. A.; Miller, D. M.; MacPherson-Krutsky, C. C.

    2013-12-01

    Geophysical investigations reveal gravity and magnetic anomalies related to a Proterozoic carbonatite terrane in the eastern Mojave Desert, host to one of the largest rare earth element carbonatite deposits in the world. The deposit is located near Mountain Pass, California and occurs in a north-northwest trending fault-bounded block that extends along the eastern parts of the Clarke Mountain Range, Mescal Range, and Ivanpah Mountains. This Early to Middle Proterozoic block is composed of a 1.7 Ga metamorphic complex of gneiss and schist intruded by a 1.4 Ga suite of ultrapotassic alkaline intrusive rocks that includes carbonatite. The intrusive suite (oldest to youngest) includes shonkinite, mesosyenite, syenite, quartz syenite, potassic granite, carbonatite, and late shonkinite dikes which are spatially and temporally associated with carbonatite intrusions and dikes. Regional geophysical data reveal that the carbonatite deposit occurs along a gravity high and the northeast edge of a prominent magnetic high with an amplitude of about 200 nanoteslas. More than 1400 gravity stations and over 200 physical property samples were collected to augment existing geophysical data and will be used to determine the geophysical and geologic setting that provide an improved structural interpretation of the eastern Mojave Desert carbonatite terrane. Physical properties of representative rock types in the area include carbonatite ore, syenite, shonkinite, gneiss, granite, and dolomite. Carbonatite intrusions typically have distinctive gravity, magnetic, and radiometric signatures because these deposits are relatively dense, contain magnetite, and are enriched in thorium or uranium. However, our results show that the main carbonatite body is essentially nonmagnetic. Thus, it is unlikely that carbonatite rocks are the source of the magnetic high associated with the Clark Mountain and Mescal Ranges. Instead, we suggest that weakly to moderately magnetic intrusive rocks or crystalline basement are the source of the magnetic high.

  3. The rare earth element potential of kaolin deposits in the Bohemian Massif (Czech Republic, Austria)

    NASA Astrophysics Data System (ADS)

    Höhn, S.; Frimmel, H. E.; Pašava, J.

    2014-12-01

    Four kaolin deposits in the Bohemian Massif were studied in order to assess the potential for the recovery of rare earth elements (REE) as by-products from the residue after extraction and refining of the raw kaolin. The behaviour of REE + Y during kaolinitization was found to be largely a function of pre-alteration mineralogy. In the examples studied, i.e. granite-derived deposits of Kriechbaum (Austria) and Boži?any, and arkose-derived deposits of Kazn?jov and Podbo?any (all Czech Republic), the REE + Y are predominantly hosted by monazite which has remained unaffected by kaolinitization. The overall REE + Y content of the variably kaolinitized rocks is strongly dependent on their genesis. While ion adsorption plays only a minor role in the concentration of REE + Y in the studied kaolinitized rocks, the processing and refining of the raw kaolin leads to residues that are enriched in REE + Y by a factor of up to 40. The use of a magnetic separator and a hydrocyclone in the processing of the raw material can yield REE + Y contents of as much as 0.77 wt%. Although this value compares well with the REE + Y concentration in some potentially economic REE + Y projects elsewhere, the overall tonnage of the (REE + Y)-enriched residue is by far not sufficient to consider economic extraction of REE + Y as by-product. Our results are most probably applicable also to other kaolin deposits derived from the weathering of Hercynian basement granites elsewhere (e.g. in Saxonia and Bavaria, Germany). Overall, the potential for REE + Y production as by-product from kaolin mining has to be regarded as minimal.

  4. Rare earth elements and critical metal content of extracted landfilled material and potential recovery opportunities.

    PubMed

    Gutiérrez-Gutiérrez, Silvia C; Coulon, Frédéric; Jiang, Ying; Wagland, Stuart

    2015-08-01

    Rare earth elements (REEs), Platinum group metals (PGMs) and other critical metals currently attract significant interest due to the high risks of supply shortage and substantial impact on the economy. Their uses in many applications have made them present in municipal solid waste (MSW) and in commercial and industrial waste (C&I), since several industrial processes produce by-products with high content of these metals. With over 4000 landfills in the UK alone, the aim of this study was to assess the existence of these critical metals within landfills. Samples collected from four closed landfills in UK were subjected to a two-step acid digestion to extract 27 metals of interest. Concentrations across the four landfill sites were 58±6mgkg(-1) for REEs comprising 44±8mgkg(-1) for light REEs, 11±2mgkg(-1) for heavy REEs and 3±1mgkg(-1) for Scandium (Sc) and 3±1.0mgkg(-1) of PGMs. Compared to the typical concentration in ores, these concentrations are too low to achieve a commercially viable extraction. However, content of other highly valuable metals (Al and Cu) was found in concentrations equating to a combined value across the four landfills of around $400 million, which increases the economic viability of landfill mining. Presence of critical metals will mainly depend on the type of waste that was buried but the recovery of these metals through landfill mining is possible and is economically feasible only if additional materials (plastics, paper, metallic items and other) are also recovered for reprocessing. PMID:25957938

  5. Rare earth element concentrations in geological and synthetic samples using synchrotron X-ray fluorescence analysis

    USGS Publications Warehouse

    Chen, J.R.; Chao, E.C.T.; Back, J.M.; Minkin, J.A.; Rivers, M.L.; Sutton, S.R.; Cygan, G.L.; Grossman, J.N.; Reed, M.J.

    1993-01-01

    The concentrations of rare earth elements (REEs) in specific mineral grains from the Bayan Obo ore deposit and synthetic high-silica glass samples have been measured by synchrotron X-ray fluorescence (SXRF) analysis using excitation of the REE K lines between 33 and 63 keV. Because SXRF, a nondestructive analytical technique, has much lower minimum detection limits (MDLs) for REEs, it is an important device that extends the in situ analytical capability of electron probe microanalysis (EPMA). The distribution of trace amounts of REEs in common rock-forming minerals, as well as in REE minerals and minerals having minor quantities of REEs, can be analyzed with SXRF. Synchrotron radiation from a bending magnet and a wiggler source at the National Synchrotron Light Source, Brookhaven National Laboratory, was used to excite the REEs. MDLs of 6 ppm (La) to 26 ppm (Lu) for 3600 s in 60-??m-thick standard samples were obtained with a 25-??m diameter wiggler beam. The MDLs for the light REEs were a factor of 10-20 lower than the MDLs obtained with a bending magnet beam. The SXRF REE concentrations in mineral grains greater than 25 ??m compared favorably with measurements using EPMA. Because EPMA offered REE MDLs as low as several hundred ppm, the comparison was limited to the abundant light REEs (La, Ce, Pr, Nd). For trace values of medium and heavy REEs, the SXRF concentrations were in good agreement with measurements using instrumental neutron activation analysis (INAA), a bulk analysis technique. ?? 1993.

  6. The sedimentary flux of dissolved rare earth elements to the ocean

    NASA Astrophysics Data System (ADS)

    Abbott, April N.; Haley, Brian A.; McManus, James; Reimers, Clare E.

    2015-04-01

    We determined pore fluid rare earth element (REE) concentrations in near-surface sediments retrieved from the continental margin off Oregon and California (USA). These sites represent shelf-to-slope settings, which lie above, within, and below the oxygen minimum zone of the Northeast Pacific. The sediments are characterized by varying degrees of net iron reduction, with pore fluids from the shelf sites being generally ferruginous, and the slope sediments having less-pronounced iron reduction zones that originate deeper in the sediment package. REE concentrations show maxima in shallow (upper 2-10 cm) subsurface pore fluids across all sites with concentrations that rise more than two orders of magnitude higher than seawater. These pore fluid enrichments highlight the importance of a sedimentary source of REEs to the ocean's water column. Here we use our measurements to estimate the diffusive flux of Nd out of ocean sediments resulting in a global flux between 18 and 110 × 106 mol Nd yr-1. While we do assume that our pore fluid profiles as well as the very limited data previously published are representative of a wide array of ocean environments, this calculated flux can account for the modeled missing Nd source flux (76 × 106 mol Nd yr-1) in global budgets (Arsouze et al., 2009). Pore fluid normalized REE patterns show distinct variation in the middle REE and heavy REE enrichments with sediment depth and amongst sites. These patterns show that the heavy REE enrichment of pore fluids at our deep slope site (3000 m water depth) is closest to the heavy REE enrichment of seawater. This observation supports the view that REE cycling within the upper ten centimeters of deep-sea marine sediments, as opposed to shallower continental shelf and slope sediments, plays a significant role in controlling the integrated global REE flux from the pore fluids and consequently the broad-scale REE pattern in seawater.

  7. C:\\Laura\\Ivtan\\Early Earth\\trace elements\\drafts\\SF08trace-revision2.doc 4:04:50 PM 7/23/2009 Volatile Element Chemistry during Metamorphism of Ordinary Chondritic Material

    E-print Network

    C:\\Laura\\Ivtan\\Early Earth\\trace elements\\drafts\\SF08trace-revision2.doc 4:04:50 PM 7/23/2009 1 Volatile Element Chemistry during Metamorphism of Ordinary Chondritic Material and Some of its Implications: 5 #12;C:\\Laura\\Ivtan\\Early Earth\\trace elements\\drafts\\SF08trace-revision2.doc 4:04:50 PM 7

  8. Determination of rare earth elements in fluid inclusions by inductively coupled plasma-mass spectrometry (ICP-MS)

    SciTech Connect

    Ghazi, A.M.; Vanko, D.A. ); Roedder, E. ); Seeley, R.C. )

    1993-09-01

    An inductively coupled plasma-mass spectrometer (ICP-MS) is used to determine rare earth element (REE) abundances in fluid inclusions. Quartz concentrates from the Bingham porphyry Cu-Mo deposit, Utah, US, and from a quartz vein in brecciated amphibolite dredged from the Mathematician Ridge, an abandoned spreading center in the eastern Pacific, were prepared by a modified crush-leach method. Leachates and solutions from acid digestion of quartz residue from leaching were analyzed by ICP-MS, using conventional sample introduction. The results demonstrate that the crush-leach method, followed by ICP-MS analysis of leachates, is effective for REE determination. Chondrite-normalized REE patterns for the Bingham samples are light rare earth elements (LREE) enriched, with a small negative Eu anomaly, and the pattern for the Mathematician Ridge sample is nearly flat, with a positive Eu anomaly.

  9. Determination of rare earth elements, uranium and thorium in geological samples by ICP-MS, using an automatic fusion machine as an alkaline digestion tool.

    NASA Astrophysics Data System (ADS)

    Granda, Luis; Rivera, Maria; Velasquez, Colon; Barona, Diego; Carpintero, Natalia

    2014-05-01

    At the present time, rare earth elements deposits have became in strategic resources for extraction of raw materials in order to manufacture high tech devices (computers, LCD, cell phones, batteries for hybrid vehicles, fiber optics and wind turbines) (1).The appropriate analytical determination of the REE ( rare earth elements) in sediment and rock samples , is important to find potential deposits and to recognize geological environments for identifying possible alterations and mineral occurrences. The alkaline fusion, which aim is to move the entire sample from solid to liquid state by forming water soluble complexes of boron and lithium, as a previous procedure for the determination of these elements, usually takes a lot of time due to the complexity of the analysis phase and by the addition of other reagents (Tm and HF ) (2) to compensate the lack of strict temperature control. The objective of this work is to develop an efficient alternative to alkaline digestion using an electrical fusion machine, which allows to create temperature programs with advanced process control and supports up to 5 samples simultaneously, which generates a reproducibility of the method and results during the melting step. Additionally, this new method permits the processing of a larger number of samples in a shorter time. The samples analyzed in this method were weighed into porcelain crucibles and subjected to calcination for 4 hours at 950 ° C in order to determine the Lost on Ignition (LOI ) , that serves to adjust the analytical results and to preserve the shelf life of the platinum ware. Subsequently, a fraction of the calcined sample was weighed into platinum crucibles and mixed with ultra-pure lithium metaborate ( flux ) 1:4 . The crucible was then placed in the fusion machine, which was programmed to take the sample from room temperature to 950 ° C in five minutes, make a small ramp to 970 ° C maintain that temperature for five minutes and download the melt in a 10 % v / v nitric acid solution . After an incorporation time, a fraction of this sample was then diluted 20 times in ultrapure deionized water ( resistivity greater 18.2 megohms / cm ). The diluted sample was analized in the ICP- MS, which was setted in high sensitivity mode. The results were compared through cross samples (the same samples tested in the laboratory were sent to another international laboratory, which works under accreditation ISO 17025 ) and no major deviations (5%) was obtained by making comparisons between the two laboratories. When comparing the results and evaluated the development of the art, it is concluded that this is an alternative that allows performing samples up to 50 alkaline fusions per day with great accuracy, saving resources and time. References: (1) British Geological Survey, Natural Environment Research Council, , Minerals UK Centre of Sustainable mineral development: Rare Earth Elements, p18-22, 2011 (2) Germain Bayon, Jean Alix Barrat, Joel Etoubleau, Mathieu Benoit ,Claire Bollinger, and Sidonie Revillon: Determination of Rare Earth Elements, Sc, Y, Zr, Ba, Hf and Th in Geological Samples by ICP-MS after Tm Addition and Alkaline Fusion, Geostandards and Geoanalytical Research, vol 33-N1, p51-62, 2008

  10. Experimental Investigation of Evaporation Behavior of Polonium and Rare-Earth Elements in Lead-Bismuth Eutectic Pool

    SciTech Connect

    Shuji Ohno; Shinya Miyahara; Yuji Kurata; Ryoei Katsura; Shigeru Yoshida

    2006-07-01

    Equilibrium evaporation behavior was experimentally investigated for polonium ({sup 210}Po) in liquid lead-bismuth eutectic (LBE) and for rare-earth elements gadolinium (Gd) and europium (Eu) in LBE to understand and clarify the transfer behavior of toxic impurities from LBE coolant to a gas phase. The experiments utilized the 'transpiration method' in which saturated vapor in an isothermal evaporation pot was transported by inert carrier gas and collected outside of the pot. While the previous paper ICONE12-49111 has already reported the evaporation behavior of LBE and of tellurium in LBE, this paper summarizes the outlines and the results of experiments for important impurity materials {sup 210}Po and rare-earth elements which are accumulated in liquid LBE as activation products and spallation products. In the experiments for rare-earth elements, non-radioactive isotope was used. The LBE pool is about 330-670 g in weight and has a surface area of 4 cm x 14 cm. {sup 210}Po experiments were carried out with a smaller test apparatus and radioactive {sup 210}Po produced through neutron irradiation of LBE in the Japan Materials Testing Reactor (JMTR). We obtained fundamental and instructive evaporation data such as vapor concentration, partial vapor pressure of {sup 210}Po in the gas phase, and gas-liquid equilibrium partition coefficients of the impurities in LBE under the temperature condition between 450 and 750 deg. C. The {sup 210}Po test revealed that Po had characteristics to be retained in LBE but was still more volatile than LBE solvent. A part of Eu tests implied high volatility of rare-earth elements comparable to that of Po. This tendency is possibly related to the local enrichment of the solute near the pool surface and needs to be investigated more. These results are useful and indispensable for the evaluation of radioactive materials transfer to the gas phase in LBE-cooled nuclear systems. (authors)

  11. Mineral chemistry of Rare Earth Element (REE) mineralization, Browns Ranges, Western Australia

    NASA Astrophysics Data System (ADS)

    Cook, Nigel J.; Ciobanu, Cristiana L.; O'Rielly, Daniel; Wilson, Robin; Das, Kevin; Wade, Benjamin

    2013-07-01

    ‘Green energy futures’ are driving unprecedented demand for Rare Earth Elements (REE), underpinning significant exploration activity worldwide. Understanding how economic REE concentrations form is critical for development of exploration models. REE mineralisation in the Browns Ranges, Gordon Downs Region, Western Australia, comprises xenotime-dominant mineralisation hosted within Archaean to Palaeoproterozoic metasedimentary units (Browns Range Metamorphics). Mineralogical, petrographic and mineral-chemical investigation, including trace element analysis by Laser-Ablation Inductively-Coupled Plasma Mass Spectroscopy, gives insights into the mineralogical distribution and partitioning of REE, and also provides evidence for the genetic evolution of the Browns Range REE mineralisation via a succession of hydrothermal processes. Two main REE-bearing minerals are identified: xenotime [(Y,REE)PO4], which is HREE selective; and subordinate florencite [(REEAl3(PO4)2(OH)6] which is LREE selective. Two morphological generations of xenotime are recognised; compositions are however consistent. Xenotime contains Dy (up to 6.5 wt.%), Er (up to 4.35 wt.%), Gd (up to 7.56 wt.%), Yb (up to 4.65 wt.%) and Y (up to 43.3 wt.%). Laser Ablation ICP-MS element mapping revealed a subtle compositional zoning in some xenotime grains. LREE appear concentrated in the grain cores or closest to the initial point of growth whereas HREE, particularly Tm, Yb and Lu, are highest at the outer margins of the grains. The HREE enrichment at the outer margins is mimicked by As, Sc, V, Sr, U, Th and radiogenic Pb. Florencite is commonly zoned and contains Ce (up to 11.54 wt.%), Nd (up to 10.05 wt.%) and La (up to 5.40 wt.%) and is also notably enriched in Sr (up to 11.63 wt.%) and Ca. Zircon (which is not a significant contributor of REEs overall due to its low abundance in the rocks) is also enriched in REE (up to 13 wt.% ?REE) and is the principal host of Sc (up to 0.8 wt.%). Early, coarse euhedral xenotime has undergone fracturing, partial breakdown and replacement by florencite. Second generation xenotime occurs as abundant small blades commonly associated with acicular hematite. Mineralization is attributed to percolation of a volatile-rich, acidic fluid, possibly granite-derived, through porous arkose units. Late hematite may suggest mixing with meteoric water and subsequent oxidation. Field observations suggest that faults acted as fluid conduits and that brecciation, possibly associated with release of volatiles from the fluid, occurred along these faults. The data provide valuable constraints on chemical compositional trends in xenotime and coexisting minerals. Given the current surge in exploration for REE, this information will assist in the development of exploration models for comparable terranes.

  12. Rare Earth Elements of Methane-Derived Authigenic Carbonates and Its Constraints on Redox Condition in the Gulf of Cadiz

    NASA Astrophysics Data System (ADS)

    Wang, S.; Magalhaes, V. H.; Fuentefria De Menezes Pinheiro, L. F.; Yan, W.

    2014-12-01

    The mineral composition, stable carbon and oxygen isotopes, and the rare earth elements (REE) concentrations in methane-derived authigenic carbonates collected from the Gulf of Cadiz were used to trace fluid sources and provide information on the associated biogeochemical processes during their formation. These samples are composed by a detrital fraction (mainly composed by quartz and clays) cemented by authigenic carbonates: aragonite and Mg-calcite, pure Mg-calcite, or dolomite and Mg-calcite. The ?13C values of the samples vary between -45.78‰ and -9.72‰ VPDB and ?18O values range from 3.67‰ to 6.92‰ VPDB. The ?13C composition is indicative of the methane-derived (probably from thermogenic gas or a mixed of thermogenic and biogenic gas) source of these carbonates. The total REE content (?REE) of these seep carbonates range from 13 to 31 ppm and average ?REE values of 21 ppm, with most of samples lower than the typical marine carbonate value of ~28 ppm. This result suggests that the REE composition of the methane-derived authigenic carbonates is controlled primarily by the migrated methane-rich fluids from which they have precipitated. The results that the REE enrichment of the samples containing dolomite and Mg-calcite minerals is higher than samples with aragonite also suggest that the authigenic mineral composition and the formation setting are important factors on the REE concentration. The shale-normalized REE patterns of the seep carbonates show no abnormality or slight positive Ce anomalies, suggesting that the formation of these seep carbonates occurs in anoxic condition. The correlation results of Ce/Ce* and LaN/SmN, Ce/Ce* and DyN/SmN, Ce/Ce* and ?REE have also suggested that the REE characteristics of most seep carbonate samples preserve the original redox conditions of their formation and that late diagenesis has little effect on the REE. Therefore, it is feasible to assume that these methane-derived authigenic carbonates represent primary carbonate phases and that they have not undergo significant diagenesis and that their geochemical and isotopic signatures reflect mainly their formation processes.

  13. Quantitative imaging of element composition and mass fraction using dual-energy CT: three-material decomposition.

    PubMed

    Liu, Xin; Yu, Lifeng; Primak, Andrew N; McCollough, Cynthia H

    2009-05-01

    In principle, dual-energy CT can only accurately decompose a mixture into two materials. To decompose a mixture into three constitute materials using dual-energy CT measurements, a third criteria must be provided to solve for three unknowns with only two spectral measurements. One solution is to assume that the sum of the volumes of three constituent materials is equivalent to the volume of the mixture (i.e., volume conservation), but this is not always true. A more generalized solution is to use the principle of mass conservation, which assumes that the sum of the masses of the three constituent materials is equivalent to the mass of the mixture. In this article, a mass-conservation based, three-material decomposition dual-energy CT algorithm is described and experimental validation of the accuracy of the technique presented. The results demonstrate that the proposed method can accurately measure elemental concentrations under low noise imaging conditions. Clinically, this may be applied to measure the mass fraction of any chemical element in a three-material mixture of solutions without the requirement of volume conservation. PMID:19544776

  14. Rare earth element metasomatism in hydrothermal systems: The Willsboro-Lewis wollastonite ores, New York, USA

    USGS Publications Warehouse

    Whitney, P.R.; Olmsted, J.F.

    1998-01-01

    Wollastonite ores and garnet-pyroxene skarns in the Willsboro-Lewis district, New York, USA were formed in a complex hydrothermal system associated with the emplacement of a large anorthosite pluton. Contact-metamorphic marbles were replaced by wollastonite, garnet, and clinopyroxene during infiltration metasomatism involving large volumes of water of chiefly meteoric origin. Rare earth elements (REE) in these rocks show large departures from the protolith REE distribution, indicative of substantial REE mobility. Three types of chondrite-normalized REE distribution patterns are present. The most common, found in ores and skarns containing andradite-rich garnet, is convex-up in the light REE (LREE) with a maximum at Pr and a positive Eu anomaly. Europium anomalies and Pr/Yb ratios are correlated with X(Ad) in garnet. This pattern (type C) results from uptake of REE from hydrothermal fluids by growing crystals of calcsilicate minerals, principally andradite, with amounts of LREE controlled by the difference in ionic radius between Ca++ and REE3+ in garnet X sites. The Eu anomaly results either from prior interaction of the fluids with plagioclase-rich, Eu-positive anorthositic rocks in and near the ore zone, or by enrichment of divalent Eu on growth surfaces of garnet followed by entrapment, or both. Relative enrichment in heavy REE (type H) occurs in ores and skarn where calcsilicates, including grossularitic garnet, in contact-metamorphic marble have been concentrated by dissolution of calcite. In most cases a negative Eu anomaly is inherited from the marble protolith. Skarns containing titanite and apatite exhibit high total REE, relative light REE enrichment, and negative Eu anomalies (type L). These appear to be intrusive igneous rocks (ferrodiorites or anorthositic gabbros) that have been converted to skarn by Ca metasomatism. REE, sequestered in titanite, apatite, and garnet, preserve the approximate REE distribution pattern of the igneous protolith. Post-ore granulite facies metamorphism homogenized zoned mineral grains without causing complete intergranular reequilibration and does not appear to have significantly affected the whole-rock REE distributions. These results demonstrate that extensive REE metasomatism can occur in hydrothermal systems at shallow to intermediate depths and that REE geochemistry may be useful in discerning the origin of skarns and skarn-related ore deposits.

  15. Natural and anthropogenic rare earth elements in Lago de Paranoá, Brasilia, Brazil

    NASA Astrophysics Data System (ADS)

    Merschel, Gila; Baldewein, Linda; Bau, Michael; Dantas, Elton Luiz; Walde, Detlef; Bühn, Bernhard

    2014-05-01

    Rare earth elements (REE) belong to the group of particle reactive elements and occur at ultratrace levels in natural waters. They are exclusively trivalent, but Ce and Eu can also be tetravalent and divalent, respectively, depending on the redox-level, the pH and the temperature of the fluid. Due to these redox changes, normalized REE patterns may show Ce and/or Eu anomalies. Recently, these high-tech metals raised significant public attention, as they are of great economic importance and consumption and hence release into the environment increased sharply. The most prominent example of a REE contamination is anthropogenic Gd, which is derived from Gd-based contrast agents used in magnetic resonance imaging. Due to their high stabilities, these compounds are not readily removed by commonly applied waste water treatment technologies and, therefore, are released from treatment plants into surface and ground waters. Hence, this anthropogenic Gd can be used as a tracer for the presence of waste water-derived substances such as pharmaceuticals and personal care products in river, lake, ground and tap waters. Lago de Paranoá is an artificial reservoir lake in the city of Brasilia, Brazil, and is currently considered a potential freshwater resource. The city's two waste water treatment plants are located on its shore and their effluents are discharged into the lake. To investigate the level of contamination, we took water samples at 11 stations in the lake and compared the REE concentrations in unfiltered and filtered (<200 nm) lake water. The unfiltered water samples show light REE enrichment (LaSN/YbSN: 1.37-1.98) and high REE concentrations (Sum REE: 192 - 476 ng/L), while the unfiltered water samples are heavy REE enriched (LaSN/YbSN: 0.15-0.61) at lower concentrations (Sum REE: 50 - 85 ng/L). This is due to the fact that light REE are preferentially bound to particle surfaces, while the heavy REE are preferentially complexed with ligands in solution. In marked contrast to the filtered samples, REE patterns of the unfiltered waters show a positive anomaly of redox-sensitive Ce. This reveals oxidative scavenging of Ce onto particles in the lake water. As lithic particles, such as atmospheric dust, do not show positive Ce anomalies, the particles responsible for Ce oxidation are either inorganic Mn or Fe (oxyhydr-) oxides or organic particulates, which are known to oxidatively scavenge Ce. All samples show pronounced positive Gd anomalies, revealing the presence of waste water-derived anthropogenic Gd in the lake waters. Because the anthropogenic Gd is bound to a very stable water-soluble chemical complex, it does not react with particles. Hence, both the filtered and unfiltered samples show REE patterns with a similar-sized positive Gd anomaly. The presence of anthropogenic Gd indicates that other waste water-derived substances of potentially high (eco-) toxicity may also be present in the lake water. This needs to be further investigated and monitored before using the lake water as a drinking water resource.

  16. Mechanism of vaporization of yttrium and rare earth elements in electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Goltz, D. M.; Grégoire, D. C.; Chakrabarti, C. L.

    1995-09-01

    The mechanism of vaporization of yttrium and the rare earth elements (REEs) has been studied using graphite furnace atomic absorption spectrometry (GFAAS) and inductively-coupled plasma mass spectrometry (ICP-MS). The appearance temperatures for Y and the REEs obtained by GFAAS were generally identical to the appearance temperatures obtained using ETV-ICP-MS. At lower temperatures, Y and the REEs are predominantly vaporized in atomic form or as oxides, while at temperatures above 2500°C, the elements are vaporized as oxides and/or carbides. This accounts for the very high sensitivity of ETV-ICP-MS compared to GFAAS for the determination of these elements. Absolute limits of detection for Y and all of the REEs using ETV-ICP-MS ranged from 0.002 pg for Tm to 0.2 pg for Ce. The use of freon as a chemical modifier was effective in controlling analyte carbide formation and reducing memory effects.

  17. Highly Sideophile Element Abundance Constraints on the Nature of the Late Accretionary Histories of Earth, Moon and Mars

    NASA Technical Reports Server (NTRS)

    Walker, R. J.; Puchtel, I. S.; Brandon, A. D.; Horan, M. F.; James, O. B.

    2007-01-01

    The highly siderophile elements (HSE) include Re, Os, Ir, Ru, Pt and Pd. These elements are initially nearly-quantitatively stripped from planetary silicate mantles during core segregation. They then may be re-enriched in mantles via continued accretion sans continued core segregation. This suite of elements and its included long-lived radiogenic isotopes systems (Re-187 (right arrow) Os-187; Pt-190 (right arrow) Os-186) can potentially be used to fingerprint the characteristics of late accreted materials. The fingerprints may ultimately be useful to constrain the prior nebular history of the dominant late accreted materials, and to compare the proportion and genesis of late accretionary materials added to the inner planets. The past ten years have seen considerable accumulation of isotopic and compositional data for HSE present in the Earth's mantle, lunar mantle and impact melt breccias, and Martian meteorites. Here we review some of these data and consider the broader implications of the compiled data.

  18. An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

    PubMed

    Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Schelter, Eric J

    2015-07-01

    Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three ?(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-earth metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359. PMID:26014901

  19. Robust elements of Snowball Earth atmospheric circulation and oases for life

    NASA Astrophysics Data System (ADS)

    Abbot, Dorian S.; Voigt, Aiko; Li, Dawei; Le Hir, Guillaume; Pierrehumbert, Raymond T.; Branson, Mark; Pollard, David; Koll, Daniel D. B.

    2013-06-01

    Atmospheric circulation in a Snowball Earth is critical for determining cloud behavior, heat export from the tropics, regions of bare ice, and sea glacier flow. These processes strongly affect Snowball Earth deglaciation and the ability of oases to support photosynthetic marine life throughout a Snowball Earth. Here we establish robust aspects of the Snowball Earth atmospheric circulation by running six general circulation models with consistent Snowball Earth boundary conditions. The models produce qualitatively similar patterns of atmospheric circulation and precipitation minus evaporation. The strength of the Snowball Hadley circulation is roughly double modern at low CO2 and greatly increases as CO2 is increased. We force a 1?D axisymmetric sea glacier model with general circulation model (GCM) output and show that, neglecting zonal asymmetry, sea glaciers would limit ice thickness variations to O(10%). Global mean ice thickness in the 1?D sea glacier model is well?approximated by a 0?D ice thickness model with global mean surface temperature as the upper boundary condition. We then show that a thin?ice Snowball solution is possible in the axysymmetric sea glacier model when forced by output from all the GCMs if we use ice optical properties that favor the thin?ice solution. Finally, we examine Snowball oases for life using analytical models forced by the GCM output and find that conditions become more favorable for oases as the Snowball warms, so that the most critical time for the survival of life would be near the beginning of a Snowball Earth episode.

  20. The Redox Dynamics of Iron in a Seasonally Waterlogged Forest Soil (Chaux Forest, Eastern France) Traced with Rare Earth Element Distribution Patterns

    NASA Astrophysics Data System (ADS)

    Steinmann, M.; Floch, A. L.; Lucot, E.; Badot, P. M.

    2014-12-01

    The oxyhydroxides of iron are common soil minerals and known to control the availability of various major and trace elements essential for biogeochemical processes. We present a study from acidic natural forest soils, where reducing redox conditions due to seasonal waterlogging lead to the dissolution of Fe-oxyhydroxides, and to the release of Fe to soil water. In order to study in detail the mechanism of redox cycling of Fe, we used Rare Earth Element (REE) distribution patterns, because an earlier study has shown that they are a suitable tool to identify trace metal sources during soil reduction in wetland soils (Davranche et al., 2011). The REE patterns of soil leachates obtained with the modified 3-step BCR extraction scheme of Rauret et al., (1999) were compared with those of natural soil water. The adsorbed fractions (F1 leach), the reducible fraction of the deepest soil horizon H4 (F2 leach, 50-120 cm), and the oxidizable fractions of horizons H2 to H4 (F3 leachs, 24-120 cm) yielded REE patterns almost identical to soil water (see figure), showing that the REE and trace metal content of soil water was mainly derived from the F1 pool, and from the F2 and F3 pools of the clay mineral-rich deep soil horizons. In contrast, the F2 leach mobilized mainly Fe-oxyhydroxides associated with organic matter of the surface soil and yielded REE patterns significantly different from those of soil water. These results suggest that the trace metal content of soil water in hydromorphic soils is primarily controlled by the clay fraction of the deeper soil horizons and not by organic matter and related Fe-oxyhydroxides of the surface soil. Additional analyses are in progress in order to verify whether the REE and trace metals of the deeper soil horizons were directly derived from clay minerals or from associated Fe-oxyhydroxide coatings. Refs cited: Davranche et al. (2011), Chem. Geol. 284; Rauret et al. (1999), J. Environ. Monit. 1.

  1. Incorporation of rare earth elements in titanite: Stabilization of the A2/a dimorph by creation of antiphase boundaries

    USGS Publications Warehouse

    Hughes, J.M.; Bloodaxe, E.S.; Hanchar, J.M.; Foord, E.E.

    1997-01-01

    The atomic arrangement of a natural rare-earth-rich titanite and two synthetic rare-earth-doped titanites have been refined in space group A2/a, and the atomic arrangement of an undoped P21/a synthetic titanite was also refined for comparison. Previous work has shown that titanite possesses a domain structure, with domains formed of like-displaced Ti atoms in the [100] octahedral chains. P21/a titanite results when the crystal is formed of a single domain, but as Ti-reversal sites occur in the octahedral chain the apparent A2/a structure results from the average of antiphase domains. Antiphase boundaries occur at O1, which is alternately overbonded or underbonded at the boundaries, depending on the displacement of the neighboring Ti atoms. Type 2 antiphase boundaries exist where two Ti atoms are displaced away from the intervening O1 atom and are energetically unfavorable because of underbonding of that O1 atom. However, substitution of a trivalent rare earth element in the adjacent Ca2+ site relieves that underbonding, favoring the creation of type 2 antiphase boundaries and stabilization of the A2/a dimorph. The results of high-precision crystal structure analyses demonstrate that rare earth substituents for Ca stabilize the A2/a dimorph at lower substitution levels than required for octahedral substitutions.

  2. [Rare earth elements content in farmland soils and crops of the surrounding copper mining and smelting plant in Jiangxi province and evaluation of its ecological risk].

    PubMed

    Jin, Shu-Lan; Huang, Yi-Zong; Wang, Fei; Xu, Feng; Wang, Xiao-Ling; Gao, Zhu; Hu, Ying; Qiao Min; Li, Jin; Xiang, Meng

    2015-03-01

    Rare earth elements content in farmland soils and crops of the surrounding copper mining and smelting plant in Jiangxi province was studied. The results showed that copper mining and smelting could increase the content of rare earth elements in soils and crops. Rare earth elements content in farmland soils of the surrounding Yinshan Lead Zinc Copper Mine and Guixi Smelting Plant varied from 112.42 to 397.02 mg x kg(-1) and 48.81 to 250.06 mg x kg(-1), and the average content was 254.84 mg x kg(-1) and 144.21 mg x kg(-1), respectively. The average contents of rare earth elements in soils in these two areas were 1.21 times and 0.68 times of the background value in Jiangxi province, 1.36 times and 0.77 times of the domestic background value, 3.59 times and 2.03 times of the control samples, respectively. Rare earth elements content in 10 crops of the surrounding Guixi Smelting Plant varied from 0.35 to 2.87 mg x kg(-1). The contents of rare earth elements in the leaves of crops were higher than those in stem and root. The contents of rare earth elements in Tomato, lettuce leaves and radish leaves were respectively 2.87 mg x kg(-1), 1.58 mg x kg(-1) and 0.80 mg x kg(-1), which were well above the hygienic standard limit of rare earth elements in vegetables and fruits (0.70 mg x kg(-1)). According to the health risk assessment method recommended by America Environmental Protection Bureau (USEPA), we found that the residents' lifelong average daily intake of rare earth elements was 17.72 mg x (kg x d)(-1), lower than the critical value of rare earth elements damage to human health. The results suggested that people must pay attention to the impact of rare earth elements on the surrounding environment when they mine and smelt copper ore in Jiangxi. PMID:25929077

  3. COST-EFFECTIVE RARE EARTH ELEMENT RECYCLING PROCESS FROM INDUSTRIAL SCRAP AND DISCARDED ELECTRONIC PRODUCTS TO VALUABLE MAGNETIC ALLOYS AND PERMANENT MAGNETS - PHASE II

    EPA Science Inventory

    Rare earth element (REE) based Nd-Fe-B and Sm-Co permanent magnets have been widely used because of their excellent magnetic properties. The applications of Nd-Fe-B and Sm-Co rare earth permanent magnets include hybrid electric vehicles (HEVs), power generators for wind tur...

  4. JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES, VOL. 118, 60176027, doi:10.1002/jgrd.50540, 2013 Robust elements of Snowball Earth atmospheric circulation

    E-print Network

    Robust elements of Snowball Earth atmospheric circulation and oases for life Dorian S. Abbot,1 Aiko Voigt Snowball Earth deglaciation and the ability of oases to support photosynthetic marine life throughout use ice optical properties that favor the thin-ice solution. Finally, we examine Snowball oases

  5. Extraction processes and solvents for recovery of cesium, strontium, rare earth elements, technetium and actinides from liquid radioactive waste

    DOEpatents

    Zaitsev, Boris N. (St. Petersburg, RU); Esimantovskiy, Vyacheslav M. (St. Petersburg, RU); Lazarev, Leonard N. (St. Petersburg, RU); Dzekun, Evgeniy G. (Ozersk, RU); Romanovskiy, Valeriy N. (St. Petersburg, RU); Todd, Terry A. (Aberdeen, ID); Brewer, Ken N. (Arco, ID); Herbst, Ronald S. (Idaho Falls, ID); Law, Jack D. (Pocatello, ID)

    2001-01-01

    Cesium and strontium are extracted from aqueous acidic radioactive waste containing rare earth elements, technetium and actinides, by contacting the waste with a composition of a complex organoboron compound and polyethylene glycol in an organofluorine diluent mixture. In a preferred embodiment the complex organoboron compound is chlorinated cobalt dicarbollide, the polyethylene glycol has the formula RC.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.n OH, and the organofluorine diluent is a mixture of bis-tetrafluoropropyl ether of diethylene glycol with at least one of bis-tetrafluoropropyl ether of ethylene glycol and bis-tetrafluoropropyl formal. The rare earths, technetium and the actinides (especially uranium, plutonium and americium), are extracted from the aqueous phase using a phosphine oxide in a hydrocarbon diluent, and reextracted from the resulting organic phase into an aqueous phase by using a suitable strip reagent.

  6. An Experimental Study on Using Rare Earth Elements to Trace Non-point source Phosphorous LossA

    NASA Astrophysics Data System (ADS)

    Liang, T.

    2011-12-01

    Controlling phosphorous (P) inputs through management of its sources and transport is critical for limiting freshwater eutrophication. Rare earth elements (REEs) have been successfully used in the analysis of soil erosion and pollutant sources, as well as in the analysis of mineral genesis. To better understand the potential for REE use in tracing non-point sources of P, we examined the combined fate of REEs and P in Chinese soils amended with REEs and documented the formation of REE-P compounds. Laboratory leaching experiments and artificial simulated rainfall experiments were conducted. Vertical leaching transfers of REEs and P were relatively small, with transport depths less than 6 cm for most REEs and P. Export of applied REEs in leachate accounted for less that 5% of inputs. The vertical mobility order of REEs and P in Chinese soils was greatest for purple soil, followed by terra nera soil, then red soil, followed by cinnamon soil, and finally loess soil. Losses of rare earth elements and P in surface runoff exhibited a parabolic relationship to simulated rainfall intensity. With greater exogenous La application, the amount of water soluble P, bicarbonate-extractable P and hydroxide-extractable P decreased significantly, while acid-extractable and residual forms of P increased significantly. In addition, characteristics of exogenous rare earth elements (REEs) and P and their losses with surface runoff (both in the water and sediments) during simulated rainfall experiments (83 mm h-1) were investigated. The results revealed that most REEs (La, 94%; Nd, 93%; Sm, 96%) and P (96%) transported with sediments in the runoff. The total amounts of losses of REEs and P in the runoff were significantly correlated, suggesting the possibility of using REEs to trace the fate of agricultural nonpoint P losses.

  7. Rare earth element contents and multiple mantle sources of the transform-related Mount Edgecumbe basalts, southeastern Alaska

    USGS Publications Warehouse

    Riehle, J.R.; Budahn, J.R.; Lanphere, M.A.; Brew, D.A.

    1994-01-01

    Pleistocene basalt of the Mount Edgecumbe volcanic field (MEF) is subdivided into a plagioclase type and an olivine type. Th/La ratios of plagioclase basalt are similar to those of mid-ocean-ridge basalt (MORB), whereas those of olivine basalt are of continental affinity. Rare earth element (REE) contents of the olivine basalt, which resemble those of transitional MORB, are modelled by 10-15% partial melting of fertile spinel-plagioclase lherzolite followed by removal of 8-13% olivine. It is concluded that olivine basalt originated in subcontinental spinel lherzolite and that plagioclase basalt may have originated in suboceanic lithosphere of the Pacific plate. -from Authors

  8. Constraints on Hadean zircon protoliths from oxygen isotopes, Ti-thermometry, and rare earth elements

    E-print Network

    Mojzsis, Stephen J.

    zircon oxygen isotope ratios and reconnaissance Ti-in-zircon concentrations, guidedConstraints on Hadean zircon protoliths from oxygen isotopes, Ti-thermometry, and rare earth Australia. Zircon oxygen isotope results bolster the view that some Hadean (>3.85 Ga) zircon source melts

  9. Partitioning of light lithophile elements during basalt eruptions on Earth and application to Martian shergottites

    E-print Network

    Edmonds, Marie

    2014-12-18

    Cosmochimica Acta 60, 3267-3283. 548 Whitworth, M.P., Rankin, A.H., 1989. Evolution of fluid phases associated with lithium 549 pegmatites from SE Ireland. Mineral. Mag 53, 271-284. 550 Wood, B.J., Blundy, J.D., 1997. A predictive model for rare earth...

  10. Mixing rare earth elements with manures to control phosphorus loss in runoff and track manure fate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concern over the enrichment of agricultural runoff with phosphorus (P) from land applied livestock manures has prompted the development of manure amendments that minimize P solubility. We evaluated the effect of mixing two rare earth chlorides, lanthanum chloride and ytterbium chloride, with poultr...

  11. Determination of rare earth elements in geological materials by inductively coupled argon plasma/atomic emission spectrometry

    USGS Publications Warehouse

    Crock, J.G.; Lichte, F.E.

    1982-01-01

    Inductively coupled argon plasma/optical emission spectrometery (ICAP/OES) is useful as a simultaneous, multielement analytical technique for the determination of trace elements in geological materials. A method for the determination of trace-level rare earth elements (REE) in geological materials using an ICAP 63-channel emission spectrometer is described. Separation and preconcentration of the REE and yttrium from a sample digest are achieved by a nitric acid gradient cation exchange and hydrochloric acid anion exchange. Precision of 1-4% relative standard deviation and comparable accuracy are demonstrated by the triplicate analysis of three splits of BCR-1 and BHVO-1. Analyses of other geological materials including coals, soils, and rocks show comparable precision and accuracy.

  12. Determination of Rare Earth Elements in Green River Shale By Inductively Coupled Plasma Mass Spectrometry Using a Desolvating Nebulizer System

    NASA Astrophysics Data System (ADS)

    Smith, F.; Clarke, D.; Moody, S.

    2014-12-01

    In this work, inductively coupled plasma mass spectrometry (ICP-MS) is applied to a geological sample for the determination of rare earth elements (REEs) using a specialized nebulizer system. The low flow desolvating nebulizer has been shown to decrease metal oxide formation which leads to a reduction in mass spectral interferences. Traditional nebulizers and spray chambers may be suitable for similar sample types, but reduction of water vapor loading to the plasma can improve REE detection limits for quadrupole-based ICP-MS. The Green River formation holds the largest oil shale deposits in the world and understanding the elemental composition of these samples is important in its study. A certified reference material, USGS Green River Shale (SGR-1), was microwave digested prior to analysis, and recoveries of REEs compared to historical values are discussed.

  13. Speciation of rare earth elements in natural terrestrial waters: assessing the role of dissolved organic matter from the modeling approach

    NASA Astrophysics Data System (ADS)

    Tang, Jianwu; Johannesson, Karen H.

    2003-07-01

    Humic Ion-Binding Model V, which focuses on metal complexation with humic and fulvic acids, was modified to assess the role of dissolved natural organic matter in the speciation of rare earth elements (REEs) in natural terrestrial waters. Intrinsic equilibrium constants for cation-proton exchange with humic substances (i.e., p KMHA for type A sites, consisting mainly of carboxylic acids), required by the model for each REE, were initially estimated using linear free-energy relationships between the first hydrolysis constants and stability constants for REE metal complexation with lactic and acetic acid. p KMHA values were further refined by comparison of calculated Model V "fits" to published data sets describing complexation of Eu, Tb, and Dy with humic substances. A subroutine that allows for the simultaneous evaluation of REE complexation with inorganic ligands (e.g., Cl -, F -, OH -, SO 42-, CO 32-, PO 43-), incorporating recently determined stability constants for REE complexes with these ligands, was also linked to Model V. Humic Ion-Binding Model V's ability to predict REE speciation with natural organic matter in natural waters was evaluated by comparing model results to "speciation" data determined previously with ultrafiltration techniques (i.e., organic acid-rich waters of the Nsimi-Zoetele catchment, Cameroon; dilute, circumneutral-pH waters of the Tamagawa River, Japan, and the Kalix River, northern Sweden). The model predictions compare well with the ultrafiltration studies, especially for the heavy REEs in circumneutral-pH river waters. Subsequent application of the model to world average river water predicts that organic matter complexes are the dominant form of dissolved REEs in bulk river waters draining the continents. Holding major solute, minor solute, and REE concentrations of world average river water constant while varying pH, the model suggests that organic matter complexes would dominate La, Eu, and Lu speciation within the pH ranges of 5.4 to 7.9, 4.8 to 7.3, and 4.9 to 6.9, respectively. For acidic waters, the model predicts that the free metal ion (Ln 3+) and sulfate complexes (LnSO 4+) dominate, whereas in alkaline waters, carbonate complexes (LnCO 3+ + Ln[CO 3] 2-) are predicted to out-compete humic substances for dissolved REEs. Application of the modified Model V to a "model" groundwater suggests that natural organic matter complexes of REEs are insignificant. However, groundwaters with higher dissolved organic carbon concentrations than the "model" groundwater (i.e., >0.7 mg/L) would exhibit greater fractions of each REE complexed with organic matter. Sensitively analysis indicates that increasing ionic strength can weaken humate-REE interactions, and increasing the concentration of competitive cations such as Fe(III) and Al can lead to a decrease in the amount of REEs bound to dissolved organic matter.

  14. NAA-SLR and ICP-AES application in the assessment of mass fraction of 19 chemical elements in pediatric and young adult prostate glands.

    PubMed

    Zaichick, Vladimir; Zaichick, Sofia

    2013-12-01

    The effect of age on the mass fraction of 19 chemical elements in the intact prostate of 50 apparently healthy 0-30-year-old males was investigated by neutron activation analysis with high-resolution spectrometry of short-lived radionuclides and inductively coupled plasma atomic emission spectrometry. Mean values (M ± standard error of the mean) for mass fraction (in milligrams per kilogram, on dry weight basis) of chemical elements were as follows: Al, 77 ± 17; B, 1.31 ± 0.29; Ba, 4.0 ± 1.2; Br, 37.7 ± 4.3; Ca, 1,536 ± 189; Cl, 13,414 ± 949; Cu, 12.3 ± 2.1; Fe, 132 ± 11; K, 11,547 ± 468; Li, 0.064 ± 0.009; Mg, 922 ± 89; Mn, 1.88 ± 0.16; Na, 9,834 ± 411; P, 6,741 ± 335; S, 8,034 ± 251; Si, 199 ± 34; Sr, 1.40 ± 0.19; and Zn, 277 ± 33. The upper limit of mean mass fraction of V was ?0.24. This work revealed that there is significant tendency for the mass fractions of Ca, K, Mg, and Zn in the prostate tissue of healthy individuals to increase with age from the time of birth up to 30 years. It means that Ca, K, Mg, and Zn mass fractions in prostate tissue are the androgen-dependent parameters. Our finding of a positive correlation between the prostatic Zn and Ca, K, Mg, P, and S mass fractions indicates that there is a special relationship of Zn with some main electrolytes (Ca, K, and Mg) and with P- and S-containing compounds in the prostate. It was shown also that high levels of Al, B, Ba, Br, Cl, Li, Na, and Sr mass fraction in prostate tissue do not indicate a direct involvement of these elements in the reproductive function of the prostate. PMID:24068488

  15. Multiple stirred-flow chamber assembly for simultaneous automatic fractionation of trace elements in fly ash samples using a multisyringe-based flow system

    SciTech Connect

    Boonjob, W.; Miro, M.; Cerda, V.

    2008-10-01

    There is a current trend in automation of leaching tests for trace elements in solid matrixes by use of flow injection based column approaches. However, as a result of the downscaled dimensions of the analytical manifold and execution of a single extraction at a time, miniaturized flow-through column approaches have merely found applications for periodic investigations of trace element mobility in highly homogeneous environmental solids. A novel flow-based configuration capitalized on stirred-flow cell extraction is proposed in this work for simultaneous fractionation of trace elements in three solid wastes with no limitation of sample amount up to 1.0 g. A two-step sequential extraction scheme involving water and acetic acid (or acetic acid/acetate buffer) is utilized for accurate assessment of readily mobilizable fractions of trace elements in fly ash samples. The W automated extraction system features high tolerance to flow rates ({<=} 6 mL min{sup -1}) and, as opposed to operationally defined batchwise methods, the solid to liquid ratio is not a critical parameter for, determination of overall readily leachable trace elements provided that exhaustive extraction is ensured. Analytical performance of the dynamic extractor is evaluated for fractionation analysis of a real coal fly ash and BCR-176R fly ash certified reference material. No significant differences were found at the 0.05 significance level between summation of leached concentrations in each fraction plus residue and concentration values of BCR-176R, thus revealing the accuracy of the automated method. Overall extractable pools of trace metals in three samples are separated in less than 115 min, even for highly contaminated ashes, versus 18-24 h per fraction in equilibrium leaching tests. The multiple stirred-flow cell assembly is thus suitable for routine risk assessment studies of industrial solid byproduct.

  16. Global in-use stocks of the rare Earth elements: a first estimate.

    PubMed

    Du, Xiaoyue; Graedel, T E

    2011-05-01

    Even though rare earth metals are indispensible in modern technology, very little quantitative information other than combined rare earth oxide extraction is available on their life cycles. We have drawn upon published and unpublished information from China, Japan, the United States, and elsewhere to estimate flows into use and in-use stocks for 15 of the metals: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. Here, we show that the combined flows into use comprised about 90 Gg in 2007; the highest for individual metals were ?28 Gg Ce and ?22 Gg La, the lowest were ?0.16 Gg Tm and ?0.15 Gg Lu. In-use stocks ranged from 144 Gg Ce to 0.2 Gg Tm; these stocks, if efficiently recycled, could provide a valuable supplement to geological stocks. PMID:21438595

  17. Halogen and phosphorus storage in the earth. [elemental spatial distribution from geochemical, geophysical, and cosmochemical factors

    NASA Technical Reports Server (NTRS)

    Smith, J. V.

    1981-01-01

    Chemical analyses of surface reservoirs, coupled with compositions for interior zones inferred from geophysical and geochemical data have been used to obtain a range of estimates of the bulk composition of the earth. It is suggested that (1) apatite with 3 wt% Fe, up to 1 wt% Cl, and 0.003 wt% Br is the principal mineral reservoir for halogens, and mica is a subsidiary reservoir; (2) apatite with 18 wt% P is the principal store of P in the upper mantle and perhaps lower mantle, but accounts for only one-twentieth of P in the earth; and (3) the remaining P is in a reservoir inaccessible to magmatism, and may amount to a maximum of 0.7 wt% in the core.

  18. Geochemical studies of rare earth elements in the Portuguese pyrite belt, and geologic and geochemical controls on gold distribution

    USGS Publications Warehouse

    Grimes, David J.; Earhart, Robert L.; de Carvalho, Delfim; Oliveira, Vitor; Oliveira, Jose T.; Castro, Paulo

    1998-01-01

    This report describes geochemical and geological studies which were conducted by the U.S. Geological Survey (USGS) and the Servicos Geologicos de Portugal (SPG) in the Portuguese pyrite belt (PPB) in southern Portugal. The studies included rare earth element (REE) distributions and geological and geochemical controls on the distribution of gold. Rare earth element distributions were determined in representative samples of the volcanic rocks from five west-trending sub-belts of the PPB in order to test the usefulness of REE as a tool for the correlation of volcanic events, and to determine their mobility and application as hydrothermal tracers. REE distributions in felsic volcanic rocks show increases in the relative abundances of heavy REE and a decrease in La/Yb ratios from north to south in the Portuguese pyrite belt. Anomalous amounts of gold are distributed in and near massive and disseminated sulfide deposits in the PPB. Gold is closely associated with copper in the middle and lower parts of the deposits. Weakly anomalous concentrations of gold were noted in exhalative sedimentary rocks that are stratigraphically above massive sulfide deposits in a distal manganiferous facies, whereas anomalously low concentrations were detected in the barite-rich, proximal-facies exhalites. Altered and pyritic felsic volcanic rocks locally contain highly anomalous concentrations of gold, suggesting that disseminated sulfide deposits and the non-ore parts of massive sulfide deposits should be evaluated for their gold potential.

  19. Highly Siderophile Elements in the Earth's Mantle as a Clock for the Moon-forming Impact

    E-print Network

    Jacobson, Seth A; Raymond, Sean N; O'Brien, David P; Walsh, Kevin J; Rubie, David C

    2015-01-01

    According to the generally accepted scenario, the last giant impact on the Earth formed the Moon and initiated the final phase of core formation by melting the Earth's mantle. A key goal of geochemistry is to date this event, but different ages have been proposed. Some argue for an early Moon-forming event, approximately 30 million years (Myr) after the condensation of the first solids in the Solar System, whereas others claim a date later than 50 Myr (and possibly as late as around 100 My) after condensation. Here we show that a Moon-forming event at 40 Myr after condensation, or earlier, is ruled out at a 99.9 per cent confidence level. We use a large number of N-body simulations to demonstrate a relationship between the time of the last giant impact on an Earth-like planet and the amount of mass subsequently added during the era known as Late Accretion. As the last giant impact is delayed, the late-accreted mass decreases in a predictable fashion. This relationship exists within both the classical scenario...

  20. Spectroscopic and electrical properties of Mg Ti ferrite doped with different rare-earth elements

    NASA Astrophysics Data System (ADS)

    Ahmed, M. A.; Ateia, E.; Salem, F. M.

    2006-05-01

    The dielectric constant ( ??), and the electric conductivity ( ?) for Mg 1+xTi xR yFe 2-2x-yO 4, 0.025? y?0.15 doped with different rare-earth ions, R=Er, Ce and Nd, were measured in the temperature range 300-750 K. The measurements were carried out as a function of frequency 50-1000 kHz X-ray diffractograms and IR spectra revealed that all the investigated samples posses the spinel structure. More than one conduction mechanism is used to interpret the electrical measurements. The most predominant one is the hopping mechanism that occurs between the ions of different valences existing on the same and different sites. All the ionic radii of the rare-earth used are too large to occupy the octahedral site. They form secondary phases on the grain boundaries. The electrical properties show that the pure sample has a larger dielectric constant as well as a larger valence exchange with respect to any doped one. This means that introducing rare-earth ions into the samples decreases ?? and increases the resistivity, owing to the decreasing Fe-Fe interaction. This feature can help to obtain well applicable ferrites.

  1. Partitioning of Inorganic Elements Consumed by Humans Between the Various Fractions of Human Wastes: A Review and Analysis of Existing Literature

    NASA Technical Reports Server (NTRS)

    Wignarajah, K.; Fisher, John W.; Pisharody, Suresh A.

    2003-01-01

    The nutritional requirements of humans and astronauts are well defined and show consistency, but the same cannot be said of human wastes. Nutrients taken up by humans can be considered to fall into two major categories - organic and inorganic fractions. Carbon, hydrogen, oxygen, nitrogen and sulfur are elements that are associated with the organic fraction. These elements are taken up in large amounts by humans and when metabolized released in wastes often in gaseous forms or as water. On the other hand, a large number of the elements are simply exchanged and can be accounted for in the liquid and solid wastes of humans. These elements fall into three major categories - cationic macroelements (e.g. Ca, K, Na, Mg and Si), anionic macroelements (e.g P, S and Cl), 17 essential microelements, (e.g. Fe, Mn, Cr, Co, Cu, Zn, Se and Sr). When provided in the recommended concentrations to an adult human, these elements should not normally accumulate in humans, but will be excreted in the different human wastes. Knowledge of the partitioning of these elements between the different human waste fractions is fundamental to understanding (a) how these elements can be recovered for reuse in space habitats, and (b) to developing the processors for waste management. The current literature is exhaustive but sometimes also conflicting. We have used the existing knowledge of nutrition and waste from medical literature and NASA documentation to develop a consensus to typify and chemically characterize the various human wastes. The partitioning of these elements has been developed into a functional model.

  2. Bernard J. Wood Jonathan D. Blundy A predictive model for rare earth element partitioning

    E-print Network

    van Westrenen, Wim

    the clinopyroxene M2 site: hi ho exp À4piM2xe ro 2 ri À ro2 1 3 ri À ro3 H d I e xe is Avogadro's number, iM2 of the atomic fraction of Mg on the clin- opyroxene M1 site, the wg-number of the melt, and . The h for any REE

  3. Matrix fractional systems

    NASA Astrophysics Data System (ADS)

    Tenreiro Machado, J. A.

    2015-08-01

    This paper addresses the matrix representation of dynamical systems in the perspective of fractional calculus. Fractional elements and fractional systems are interpreted under the light of the classical Cole-Cole, Davidson-Cole, and Havriliak-Negami heuristic models. Numerical simulations for an electrical circuit enlighten the results for matrix based models and high fractional orders. The conclusions clarify the distinction between fractional elements and fractional systems.

  4. Elemental Modes of Occurrence in an Illinois #6 Coal and Fractions Prepared by Physical Separation Techniques at a Coal Preparation Plant

    SciTech Connect

    Huggins, F.; Seidu, L; Shah, N; Huffman, G; Honaker, R; Kyger, J; Higgins, B; Robertson, J; Pal, S; Seehra, M

    2009-01-01

    In order to gain better insight into elemental partitioning between clean coal and tailings, modes of occurrence have been determined for a number of major and trace elements (S, K, Ca, V, Cr, Mn, Fe, Zn, As, Se, Pb) in an Illinois No.6 coal and fractions prepared by physical separation methods at a commercial coal preparation plant. Elemental modes of occurrence were largely determined directly by XAFS or Moessbauer spectroscopic methods because the concentrations of major minerals and wt.% ash were found to be highly correlated for this coal and derived fractions, rendering correlations between individual elements and minerals ambiguous for inferring elemental modes of occurrence. Of the major elements investigated, iron and potassium are shown to be entirely inorganic in occurrence. Most (90%) of the iron is present as pyrite, with minor fractions in the form of clays and sulfates. All potassium is present in illitic clays. Calcium in the original coal is 80-90% inorganic and is divided between calcite, gypsum, and illite, with the remainder of the calcium present as carboxyl-bound calcium. In the clean coal fraction, organically associated Ca exceeds 50% of the total calcium. This organically-associated form of Ca explains the poorer separation of Ca relative to both K and ash. Among the trace elements, V and Cr are predominantly inorganically associated with illite, but minor amounts (5-15% Cr, 20-30% V) of these elements are also organically associated. Estimates of the V and Cr contents of illite are 420 ppm and 630 ppm, respectively, whereas these elements average 20 and 8 ppm in the macerals. Arsenic in the coal is almost entirely associated with pyrite, with an average As content of about 150 ppm, but some As ({approx} 10%) is present as arsenate due to minor oxidation of the pyrite. The mode of occurrence of Zn, although entirely inorganic, is more complex than normally noted for Illinois basin coals; about 2/3 is present in sphalerite, with lesser amounts associated with illite and a third form yet to be conclusively identified. The non-sulfide zinc forms are removed predominantly by the first stage of separation (rotary breaker), whereas the sphalerite is removed by the second stage (heavy media). Germanium is the only trace element determined to have a predominantly organic association.

  5. On the determination of the long period tidal perturbations in the elements of artificial earth satellites

    NASA Technical Reports Server (NTRS)

    Musen, P.; Felsentreger, T.

    1972-01-01

    The magnitude of the tidal effects depends upon the elastic properties of the earth as described by Love numbers. The Love numbers appear as the coefficients in the expansion of the exterior tidal potential in terms of spherical harmonics (in Maxwellian form). A single averaging process was performed only along the parallels of latitude. This process preserves additional long period tidal effects (with periods of a few days or more). It also eliminates the short period effects with periods of one day or less.

  6. New fission fragment distributions and r-process origin of the rare-earth elements

    E-print Network

    Goriely, S; Lemaitre, J -F; Panebianco, S; Dubray, N; Hilaire, S; Bauswein, A; Janka, H -Thomas

    2013-01-01

    Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process elements with nuclear mass numbers A > 140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular the fission fragment yields determine the creation of 110 140.

  7. Trace element determination in crude oil and its fractions by inductively coupled plasma mass spectrometry using ultrasonic nebulization of toluene solutions

    NASA Astrophysics Data System (ADS)

    Duyck, Christiane; Miekeley, Norbert; Porto da Silveira, Carmem L.; Szatmari, Peter

    2002-12-01

    A method was developed for the determination of trace elements in crude oil by inductively coupled plasma mass spectrometry (ICP-MS) after sample dissolution in toluene and subsequent ultrasonic nebulization (USN). Carbon build-up at the interface and ion lenses was minimized by optimization of the argon to oxygen ratio in the plasma and by the desolvating action of the USN. The analyte addition technique, combined with internal standardization ( 115In), was the only calibration procedure capable to correct properly for signal suppression, especially observed in solutions with higher concentrations of asphaltenes. Analytical curves with good linearity ( r2>0.99), and solution detection limits (LOD-3?) of ?0.1 ?g l -1 for V, Ni, Co, Y, Mo, Cd, Ba and La, and in the range of 0.1-1 ?g l -1 for Al, Ti, Fe, Zn, Sr, Ag, Sn and Pb were obtained. Method validation was performed by analyzing two certified reference materials. For National Institute for Standards and Technology (NIST) 1634c (V, Ni, Co), accuracy was approximately 10%, similar as observed for other 12 elements in NIST 1084a. Asphaltenes were separated from the oil bulk of crude oil samples from the Potiguar Basin (Brazil) using precipitation in heptane. The heptane-soluble fraction (maltenes) was separated by elution chromatography into three sub-fractions: (1) saturated and low molecular mass (MM) aromatics, (2) aromatics and low MM polar compounds, and (3) high MM polar compounds (resins). Trace elements were determined in these fractions after dissolution in toluene, by USN-ICP-MS. Mass balance calculations showed a significant increase of most elements (10-30 times) in the asphaltenic fraction, and in minor proportions in fraction 3, compared to the crude oil samples. Comparison with microwave-assisted acid decomposition showed good agreement, validating the proposed methodology and emphasizing its applicability for routine analysis of crude oil and other toluene soluble petroleum products.

  8. Alkaline-Earth-Metal-Induced Liberation of Rare Allotropes of Elemental Silicon and Germanium from N-Heterocyclic Metallylenes.

    PubMed

    Blom, Burgert; Said, Amro; Szilvási, Tibor; Menezes, Prashanth W; Tan, Gengwen; Baumgartner, Judith; Driess, Matthias

    2015-09-01

    The synthesis and striking reactivity of the unprecedented N-heterocyclic silylene and germylene ("metallylene") alkaline-earth metal (Ae) complexes of the type [(?(5)-C5Me5)2Ae?:E(N(t)BuCH)2] (3, 4, and 7-9; Ae = Ca, E = Ge 3; Ae = Sr, E = Ge 4; Ae = Sr, E = Si 7; Ae = Ba, E = Si 8; Ae = Ba, E = Ge 9) are reported. All complexes have been characterized by spectroscopic means, and their bonding situations investigated by density functional theory (DFT) methods. Single-crystal X-ray diffraction analyses of examples revealed relatively long Si-Ae and Ge-Ae distances, respectively, indicative of weak E:?Ae (E = Si, Ge) dative bonds, further supported by the calculated Wiberg bond indices , which are rather low in all cases (?0.5). Unexpectedly, the complexes undergo facile transformation to 1,4-diazabuta-1,3-diene Ae metal complexes of the type [(?(5)-C5Me5)2Ae(?(2)-{N(t)Bu?CHCH?N(t)Bu})] (Ae = Sr 10, Ae = Ba 11) or in the case of calcium to the dinuclear complex [(?(5)-C5Me5)2Ca?:N((t)Bu)?CHCH?((t)Bu)N:?Ca(?(5)-C5Me5)2] (12) under concomitant liberation of elemental silicon and germanium. The formation of elemental silicon and germanium is proven by inductively coupled plasma atomic emission spectroscopy, transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray spectroscopy. Notably, the decomposition of the Si(II)?Ba complex 8 produces allo-silicon, a rare allotropic form of elemental silicon. Similarly, the analogous Ge(II)?Ba complex 9, upon decomposition, forms tetragonal germanium, a dense and rare allotrope of elemental germanium. The energetics of this unprecedented alkaline-earth-metal-induced liberation of elemental silicon and germanium was additionally studied by DFT methods, revealing that the transformations are pronouncedly exergonic and considerably larger for the N-heterocyclic germylene complexes than those of the corresponding silicon analogues. PMID:26305163

  9. Geochemical variations of rare earth elements in Marcellus shale flowback waters and multiple-source cores in the Appalachian Basin

    NASA Astrophysics Data System (ADS)

    Noack, C.; Jain, J.; Hakala, A.; Schroeder, K.; Dzombak, D. A.; Karamalidis, A.

    2013-12-01

    Rare earth elements (REE) - encompassing the naturally occurring lanthanides, yttrium, and scandium - are potential tracers for subsurface groundwater-brine flows and geochemical processes. Application of these elements as naturally occurring tracers during shale gas development is reliant on accurate quantitation of trace metals in hypersaline brines. We have modified and validated a liquid-liquid technique for extraction and pre-concentration of REE from saline produced waters from shale gas extraction wells with quantitative analysis by ICP-MS. This method was used to analyze time-series samples of Marcellus shale flowback and produced waters. Additionally, the total REE content of core samples of various strata throughout the Appalachian Basin were determined using HF/HNO3 digestion and ICP-MS analysis. A primary goal of the study is to elucidate systematic geochemical variations as a function of location or shale characteristics. Statistical testing will be performed to study temporal variability of inter-element relationships and explore associations between REE abundance and major solution chemistry. The results of these analyses and discussion of their significance will be presented.

  10. Residential heating contribution to level of air pollutants (PAHs, major, trace, and rare earth elements): a moss bag case study.

    PubMed

    Vukovi?, Gordana; Uroševi?, Mira Ani?i?; Pergal, Miodrag; Jankovi?, Milan; Goryainova, Zoya; Tomaševi?, Milica; Popovi?, Aleksandar

    2015-12-01

    In areas with moderate to continental climates, emissions from residential heating system lead to the winter air pollution peaks. The EU legislation requires only the monitoring of airborne concentrations of particulate matter, As, Cd, Hg, Ni, and B[a]P. Transition metals and rare earth elements (REEs) have also arisen questions about their detrimental health effects. In that sense, this study examined the level of extensive set of air pollutants: 16 polycyclic aromatic hydrocarbons (PAHs), and 41 major elements, trace elements, and REEs using Sphagnum girgensohnii moss bag technique. During the winter of 2013/2014, the moss bags were exposed across Belgrade (Serbia) to study the influence of residential heating system to the overall air quality. The study was set as an extension to our previous survey during the summer, i.e., non-heating season. Markedly higher concentrations of all PAHs, Sb, Cu, V, Ni, and Zn were observed in the exposed moss in comparison to the initial values. The patterns of the moss REE concentrations normalized to North American Shale Composite and Post-Archean Australian Shales were identical across the study area but enhanced by anthropogenic activities. The results clearly demonstrate the seasonal variations in the moss enrichment of the air pollutants. Moreover, the results point out a need for monitoring of air quality during the whole year, and also of various pollutants, not only those regulated by the EU Directive. PMID:26213134

  11. Crystal structure of tveitite-(Y): Fractionation of rare-earth elements between positions and the variety of defects

    SciTech Connect

    Yakubovich, O. V. Massa, W.; Pekov, I. V.; Gavrilenko, P. G.

    2007-02-15

    The crystal structure of the mineral tveitite-(Y) (Y{sub 0.883}Na{sub 0.106}) (Ca{sub 0.841}LREE{sub 0.159})(Ca{sub 0.716}Na{sub 0.204}HREE{sub 0.080})(Ca{sub 0.0=} 9{sub 2}Na{sub 0.074})F{sub 6.952} from amazonite pegmatites of Rov-Gora Mountain (Keivy, Kola Peninsula) is determined using X-ray diffraction (Stoe IPDS diffractometer, {lambda}MoK{sub {alpha}}, graphite monochromator, 2{theta}{sub max} = 63.5{sup o}, R = 0.051 for 1542 reflections). The main crystal data are as follows: a = 17.020(2) A, c = 9.679(2) A, V = 2428.2(4) A{sup 3}, space group R3-bar, Z = 18, and {rho}{sub calcd} = 4.00 g/cm{sup 3}. The idealized structural formula of the mineral is represented as (Y,Na){sub 6}(Ca,LREE){sub 6}(Ca,Na,HREE){sub 6}(Ca,Na)F{sub 42} (Z = 3). The defect structure of the mineral manifests itself in a mixed occupation of all four independent cation positions and in a randomly disordered distribution of fluorine atoms over the majority of anion positions. It is shown that the crystal structure of tveitite-(Y) fulfills the function of an 'Eratosthenes sieve' for yttrium cations and two groups of lanthanide cations, so that these cations are distributed over three different positions.

  12. Modeling Multi-Phase Flow and Energy Transport in the Earth's Crust by Combined Finite Element and Finite Volume Methods

    NASA Astrophysics Data System (ADS)

    Geiger, S.; Matthai, S. K.; Roberts, S. G.; Driesner, T.

    2001-12-01

    The challenge about modeling multi-phase flow and energy transport (e.g., in hydrothermal systems) is to define a a robust numerical solution for the highly non-linear governing equations [1]. Additionally, the numerical solution should be able to deal with flow parameters (permeability, porosity, velocity) and fluid properties (density, viscosity, compressibility) that often vary over several orders of magnitude, as well as the geometric complexity of the geologic media. We found that combining higher order finite element and total variation diminishing (TVD) finite volume methods is an efficient way to accurately model multi-phase flow and energy transport. Employing an approach that conserves the fluid volume rather than the fluid mass, we compute the fluid pressure and fluid velocities using finite elements with quadratic-barycentric interpolation functions. Fluid phases are propagated using the fluid velocities and a TVD finite volume methods Fluid properties are computed iteratively for the given temperature and pressure using an equation of state for H2O and are fed back into the transport algorithm. Finite element and finite volume methods yield the advantage that they can be employed on unstructured and adaptively refined grids and hence deal efficiently with complex geometries. The fluid volume conservative approach allows us to track accurately changes in the fluid volume fractions due to the varying compressibility of the fluids. The quadratic-barycentric interpolation functions yield an accurate integration of the fluid pressure and fluid density field across the finite element and exact fluid velocities at the element integration points. The TVD finite volume method preserves any shock-fronts occurring during the propagation of the fluid phases while avoiding spurious oscillations and numerical diffusion. As an application of the proposed numerical method, we show the convection of water and steam around a magmatic intrusion. [1] Huyakorn, P.S. and Pinder, G.F., Computational methods in subsurface flow. Academic Press, 473 pages, 1987.

  13. Removal of alkaline-earth elements by a carbonate precipitation in a chloride molten salt

    SciTech Connect

    Yung-Zun Cho; In-Tae Kim; Hee-Chui Yang; Hee-Chui Eun; Hwan-Seo Park; Eung-Ho Kim

    2007-07-01

    Separation of some alkaline-earth chlorides (Sr, Ba) was investigated by using carbonate injection method in LiCl-KCl eutectic and LiCl molten salts. The effects of the injected molar ratio of carbonate([K{sub 2}(or Li{sub 2})CO{sub 3}/Sr(or Ba)Cl{sub 2}]) and the temperature(450-750 deg.) on the conversion ratio of the Sr or Ba carbonate were determined. In addition, the form of the Sr and Ba carbonate resulting from the carbonation reaction with carbonates was identified via XRD and SEM-EDS analysis. In these experiments, the carbonate injection method can remove Sr and Ba chlorides effectively over 99% in both LiCl-KCl eutectic and LiCl molten salt conditions. When Sr and Ba were co-presented in the eutectic molten salt, they were carbonated in a form of Ba{sub 0.5}Sr{sub 0.3}CO{sub 3}. And when Sr was present in LiCl molten salt, it was carbonated in the form of SrCO{sub 3}. Carbonation ratio increased with a decreasing temperature and it was more favorable in the case of a K{sub 2}CO{sub 3} injection than that of Li{sub 2}CO{sub 3}. Based on this experiment, it is postulated that carbonate precipitation method has the potential for removing alkali-earth chlorides from LiCl-KCl eutectic and LiCl molten salts. (authors)

  14. Chemodynamical Deuterium Fractionation in the Early Solar Nebula: The Origin of Water on Earth and in Asteroids and Comets

    NASA Astrophysics Data System (ADS)

    Albertsson, T.; Semenov, D.; Henning, Th.

    2014-03-01

    Formation and evolution of water in the solar system and the origin of water on Earth constitute one of the most interesting questions in astronomy. The prevailing hypothesis for the origin of water on Earth is by delivery through water-rich small solar system bodies. In this paper, the isotopic and chemical evolution of water during the early history of the solar nebula, before the onset of planetesimal formation, is studied. A gas-grain chemical model that includes multiply deuterated species and nuclear spin-states is combined with a steady-state solar nebula model. To calculate initial abundances, we simulated 1 Myr of evolution of a cold and dark TMC-1-like prestellar core. Two time-dependent chemical models of the solar nebula are calculated over 1 Myr: (1) a laminar model and (2) a model with two-dimensional (2D) turbulent mixing. We find that the radial outward increase of the H2O D/H ratio is shallower in the chemodynamical nebular model than in the laminar model. This is related to more efficient defractionation of HDO via rapid gas-phase processes because the 2D mixing model allows the water ice to be transported either inward and thermally evaporated or upward and photodesorbed. The laminar model shows the Earth water D/H ratio at r <~ 2.5 AU, whereas for the 2D chemodynamical model this zone is larger, r <~ 9 AU. Similarly, the water D/H ratios representative of the Oort-family comets, ~2.5-10 × 10-4, are achieved within ~2-6 AU and ~2-20 AU in the laminar and the 2D model, respectively. We find that with regards to the water isotopic composition and the origin of the comets, the mixing model seems to be favored over the laminar model.

  15. Chemodynamical deuterium fractionation in the early solar nebula: The origin of water on earth and in asteroids and comets

    SciTech Connect

    Albertsson, T.; Semenov, D.; Henning, Th.

    2014-03-20

    Formation and evolution of water in the solar system and the origin of water on Earth constitute one of the most interesting questions in astronomy. The prevailing hypothesis for the origin of water on Earth is by delivery through water-rich small solar system bodies. In this paper, the isotopic and chemical evolution of water during the early history of the solar nebula, before the onset of planetesimal formation, is studied. A gas-grain chemical model that includes multiply deuterated species and nuclear spin-states is combined with a steady-state solar nebula model. To calculate initial abundances, we simulated 1 Myr of evolution of a cold and dark TMC-1-like prestellar core. Two time-dependent chemical models of the solar nebula are calculated over 1 Myr: (1) a laminar model and (2) a model with two-dimensional (2D) turbulent mixing. We find that the radial outward increase of the H{sub 2}O D/H ratio is shallower in the chemodynamical nebular model than in the laminar model. This is related to more efficient defractionation of HDO via rapid gas-phase processes because the 2D mixing model allows the water ice to be transported either inward and thermally evaporated or upward and photodesorbed. The laminar model shows the Earth water D/H ratio at r ? 2.5 AU, whereas for the 2D chemodynamical model this zone is larger, r ? 9 AU. Similarly, the water D/H ratios representative of the Oort-family comets, ?2.5-10 × 10{sup –4}, are achieved within ?2-6 AU and ?2-20 AU in the laminar and the 2D model, respectively. We find that with regards to the water isotopic composition and the origin of the comets, the mixing model seems to be favored over the laminar model.

  16. Strong Thermal Anomalies in the Lowermost Mantle Explain a Large Fraction of Deep Earth Seismic Structure (Invited)

    NASA Astrophysics Data System (ADS)

    Schuberth, B. S.; Bunge, H.

    2010-12-01

    One major challenge in the study of Earth's deep interior is to improve existing conceptual models of mantle flow. Understanding the dynamic behavior of the mantle is important as it drives plate tectonics and controls the way the Earth looses its heat. Thus, it is a crucial factor in tectonic modeling or in simulations of the geodynamo and of the thermal history of the Earth. In the last decade, the classical viewpoint has been put into question that only a small part of the heat leaving the mantle at the top is coming from the underlying core (2-3 TW or ~5% of the total surface heat flux). A number of studies from various fields have recently promoted the idea of a much larger core contribution to the mantle energy budget of as much as 10 TW (~30% of the surface heat flow). For example, finite frequency tomography has produced images of large plumes in the lower mantle, which potentially carry a significant amount of heat to the surface (Nolet et al. [2006]). This strengthens the notion that the dynamic role of these plumes is larger than inferred classically from observation of dynamic topography. Here, we demonstrate that plume structures predicted for such a high core heat flux by high-performance computations of 3-D mantle flow are compatible with seismic tomography and small rates of polar wander. An important aspect in such comparisons is that the resolving power of seismic tomography is limited due to uneven data coverage. One possibility to account for this effect is to apply the resolution operator of the tomographic inversions to our synthetic structures. However, this operator can only be constructed for tomographic models with a small number of free parameters, thus limiting its use. Therefore, we will explore new ways to test dynamic flow calculations for Earth's mantle against seismic data and tomographic models. One possible approach is to perform large-scale simulations of 3-D seismic wave propagation through both tomographic models as well as our predicted elastic structures of the mantle. This bears the potential to directly test the resulting synthetic seismograms against real data.

  17. Annual budget of Gd and related Rare Earth Elements in a river basin heavily disturbed by anthropogenic activities.

    NASA Astrophysics Data System (ADS)

    Hissler, Christophe; Stille, Peter; Guignard, Cédric; François Iffly, Jean; Pfister, Laurent

    2014-05-01

    The real environmental impact of micropollutants in river systems can be difficult to assess, essentially due to uncertainties in the estimation of the relative significance of both anthropogenic and natural sources. The natural geochemical background is characterized by important variations at global, regional or local scales. Moreover, elements currently considered to be undisturbed by human activities and used as tracers of continental crust derived material have become more and more involved in industrial or agricultural processes. The global production of lanthanides (REE), used in industry, medicine and agriculture, for instance, has increased exponentially from a few tons in 1950 to projected 185 kt in 2015. Consequently, these new anthropogenic contributions impact the natural cycle of the REE. Gd and related REE are now worldwide recognized as emergent micropollutants in river systems. Nevertheless, there is still a gap concerning their temporal dynamics in rivers and especially the quantification of both the anthropogenic and natural contributions in surface water. The acquisition of such quantitative information is of primordial interest because elements from both origins may present different bioavailability and toxicity levels. Working at the river basin scale allows for quantifying micropollutant fluxes. For this reason, we monitored water quality and discharge of the Alzette River (Luxembourg, Europe) over two complete hydrological cycles (2010-2013). The substantial contamination, is principally due to the steel industry in the basin, which has been active from 1875 until now, and to the related increase of urban areas. The particulate and dissolved fractions of river water were monitored using a multitracer approach (standard parameters for water quality including REE concentrations, Pb, Sr, Nd radiogenic isotopes) with two sampling setups (bi-weekly and flood event based sampling). This extensive sampling design allowed quantifying the annual budget of the REE in the particulate and dissolved fractions of the river water and the waste water treatment plant effluents. Enrichments in Gd have been observed for the dissolved fraction of the water during low water levels. This enrichment has not been detected in the surrounding soils of the basin and can be related to the effluents of the waste water treatment plants, which control the REE chemistry of the dissolved fraction during the low water period. When flood events occur, the Gd anomaly progressively disappears and gives way to the chemical signature of the basin soils. The REE and intense hydrological monitoring we performed at the same time allowed for the annual quantification of the anthropogenic vs. natural REE fluxes in the river water of this heavily polluted basin.

  18. Determination of rare-earth elements in uranium-bearing materials by inductively coupled plasma mass spectrometry.

    PubMed

    Varga, Zsolt; Katona, Róbert; Stefánka, Zsolt; Wallenius, Maria; Mayer, Klaus; Nicholl, Adrian

    2010-03-15

    A novel and simple analytical procedure has been developed for the trace-level determination of lanthanides (rare-earth elements) in uranium-bearing materials by inductively coupled plasma sector-field mass spectrometry (ICP-SFMS). The method involves a selective extraction chromatographic separation of lanthanides using TRU resin followed by ICP-SFMS analysis. The limits of detection of the method proposed is in the low pg g(-1) range, which are approximately two orders of magnitude better than that of without chemical separation. The method was validated by the measurement of reference material and applied for the analysis of uranium ore concentrates (yellow cakes) for nuclear forensic purposes, as a potential application of the methodology. PMID:20152406

  19. Laser-excited fluorescence of rare earth elements in fluorite: Initial observations with a laser Raman microprobe

    USGS Publications Warehouse

    Burruss, R.C.; Ging, T.G.; Eppinger, R.G.; Samson, a.M.

    1992-01-01

    Fluorescence emission spectra of three samples of fluorite containing 226-867 ppm total rare earth elements (REE) were excited by visible and ultraviolet wavelength lines of an argon ion laser and recorded with a Raman microprobe spectrometer system. Narrow emission lines ( 0.9 for Eu2+ and 0.99 for Er3+. Detection limits for three micrometer spots are about 0.01 ppm Eu2+ and 0.07 ppm Er3+. These limits are less than chondrite abundance for Eu and Er, demonstrating the potential microprobe analytical applications of laser-excited fluorescence of REE in fluorite. However, application of this technique to common rock-forming minerals may be hampered by competition between fluorescence emission and radiationless energy transfer processes involving lattice phonons. ?? 1992.

  20. Columbium-, rare-earth-element-, and thorium-bearing veins near Salmon Bay, Southeastern Alaska. Open file report

    SciTech Connect

    Warner, J.D.

    1989-01-01

    In 1984 and 1985 the Bureau of Mines investigated radioactive carbonate veins near Salmon Bay, southeastern Alaska, for concentrations of columbium and associated metals. The veins cut units of graywacke, conglomerate, argillite, and limestone and range in width from less than an inch to greater than 10 ft and have a length ranging from less than a hundred to greater than 1,000 ft. Mineralogy of the veins is complex, and includes thorite, the rare-earth-element minerals monazite, parisite, and bastnaesite, and a columbium mineral that is speculated to be columbite. Gangue minerals include ankerite, dolomite, siderite, quartz and albite. More than seventy veins were sampled but only three contain elevated metal concentrations along a significant strike length. These resources are small compared to columbium, REE, and thorium resources elsewhere in the world.

  1. Determination of rare earth elements in dust deposited on tree leaves from Greater Cairo using inductively coupled plasma mass spectrometry.

    PubMed

    Shaltout, Abdallah A; Khoder, M I; El-Abssawy, A A; Hassan, S K; Borges, Daniel L G

    2013-07-01

    This work aims at monitoring the rare earth elements (REEs) and Th in dust deposited on tree leaves collected inside and outside Greater Cairo (GC), Egypt. Inductively coupled plasma mass spectrometry (ICP-MS) was employed. The concentration of REEs in the collected dust samples was found to be in the range from 1 to 60 ?g g(-1). The highest concentration of REEs was found in dust samples collected outside GC, in the middle of the Nile Delta. This would refer to the availability of black sands, due to desert wind occurrence during the sample collection, and anthropogenic activities. The limits of detection of the REEs ranged from 0.02 ng g(-1) for Tm to 3 ng g(-1) for Yb. There was an obvious variation in the concentration of REEs inside and outside GC due to variations of natural and anthropogenic sources. Strong correlations among all the REEs were found. PMID:23583939

  2. Synthesis of mixed-ligand complexes of rare-earth elements

    SciTech Connect

    Panyushkin, V.T.; Akhrimenko, N.V.

    1994-09-10

    The authors have synthesized mixed-ligand complexes of Nd(III), Sm(III), Eu(III), Tb(III), Dy(III), Ho(III), Er(III), and Yb(III) with acetylacetone (I) and unsaturated organic acids (II): maleic, fumaric, acrylic, and methacrylic. According to elemental analyses and thermogravimetric data the composition of Ln(I){sub 2}(II) {center_dot} 3H{sub 2}O does not depend on the basicity of the acid. The structure of compounds prepared was studied by IR, NMR, and luminescent spectroscopy.

  3. Rare earth and other elements in components of the Abee enstatite chondrite

    NASA Technical Reports Server (NTRS)

    Frazier, R. M.; Boynton, W. V.

    1985-01-01

    Radiochemical and instrumental neutron activation analyses of REEs and other elements have been conducted for Abee clast samples, a matrix sample, a dark inclusion, magnetic and nonmagnetic samples, and bulk samples. Correlations of the REEs and oldhamite abundance for both the clasts and dark inclusions indicate that the REEs chiefly occur in oldhamite. The similar REE patterns for clasts and dark inclusions, and the similar mineral composition of oldhamite in clast and dark inclusions, suggest that the oldhamite in both the clasts and dark inclusions is of a common origin.

  4. Macro- and microelements including rare earth elements in some soils of the Sakhalin Island

    NASA Astrophysics Data System (ADS)

    Vodyanitskii, Yu. N.; Manakhov, D. V.; Savichev, A. T.

    2015-10-01

    Specific features of the chemical composition of burozems, podzols, and alluvial soils of the Sakhalin Island are revealed. Burozems on eluvial and colluvial deposits, podzols on marine sediments, and alluvial soils are enriched in Al and Ga and impoverished in Ca, P, and Sr. Burozems and alluvial soil contain more Fe than podzols. The gleyic burozem is very rich in chlorine. Podzols are depleted of Mn, Ni, Cu, and Zn, as well as of heavy lanthanide Y; they are rich in Ba, Sr, Na, K, and light lanthanides (La, Ce, Pr, Nd). The podzolization process affects the migration of manganese oxides as the carriers of lanthanides and Th and controls their distribution in the soil profiles. The alluvial soil is enriched in Na, K, Mg, and Zn; and it is depleted of Cu. The heavy lanthanide Y is included in other alluvium minerals than the light lanthanides (from La to Nd). The ash matter of the litter horizons is insignificantly enriched in Rb and Ni; the fir forest litter contains more Mg, Ca, Mn, S, and Zn than that under larch. In the larch-cedar forest growing on podzols, the litter poorly accumulates all the studied elements, except for Ca, Mn, P, and S; the litter of sedge-reed grass association on the alluvial soil surface slightly accumulates all the studied elements, except for Mn, P, and S.

  5. Rare-earth element mineralisation within the Mt. Weld carbonatite laterite, Western Australia

    NASA Astrophysics Data System (ADS)

    Lottermoser, B. G.

    1990-03-01

    A thick weathering profile of a Proterozoic carbonatite intrusion possesses exceptionally high REE contents in the form of abundant secondary phosphates and aluminophosphates. REE experienced pronounced lateral and vertical mobility during weathering which was favoured by high fluid/rock ratios, long fluid residence times, abundant REE complexing agents in the groundwater solutions and the ready decomposition of primary igneous carbonatite minerals. The wide range of pH and alkalinity conditions, and carbonate anion concentrations in the groundwater solutions variably influenced the different stabilities of LREE and HREE complexes which caused fractionation, separation and deposition of LREE and HREE. Chemical-crystallographic controls and adsorption of REE onto non-crystalline substances led to the incorporation of LREE into plumbogummite-group minerals, rhabdophane and secondary monazite in the upper part of the weathering profile, whereas HREE and Y were preferentially incorporated into churchite at lower levels. lateral groundwater flow towards a central topographic low of the laterite and associated decreasing pH of the solutions favoured the mobilisation of large amounts of REE and the formation of a highly REE-enriched laterite centre.

  6. Venus, Earth, Xenon

    NASA Astrophysics Data System (ADS)

    Zahnle, K. J.

    2013-12-01

    Xenon has been regarded as an important goal of many proposed missions to Venus. This talk is intended to explain why. Despite its being the heaviest gas found in natural planetary atmospheres, there is more evidence that Xe escaped from Earth than for any element apart from helium: (i) Atmospheric Xe is very strongly mass fractionated (at about 4% per amu) from any known solar system source. This suggests fractionating escape that preferentially left the heavy Xe isotopes behind. (ii) Xe is underabundant compared to Kr, a lighter noble gas that is not strongly mass fractionated in air. (iii) Radiogenic Xe is strongly depleted by factors of several to ~100 compared to the quantities expected from radioactive decay of primordial solar system materials. In these respects Xe on Mars is similar to Xe on Earth, but with one key difference: Xe on Mars is readily explained by a simple process like hydrodynamic escape that acts on an initially solar or meteoritic Xe. This is not so for Earth. Earth's Xe cannot be derived by an uncontrived mass fractionating process acting on any known type of Solar System Xe. Earth is a stranger, made from different stuff than any known meteorite or Mars or even the Sun. Who else is in Earth's family? Comets? We know nothing. Father Zeus? Data from Jupiter are good enough to show that jovian Xe is not strongly mass-fractionated but not good enough to determine whether Jupiter resembles the Earth or the Sun. Sister Venus? Noble gas data from Venus are incomplete, with Kr uncertain and Xe unmeasured. Krypton was measured by several instruments on several spacecraft. The reported Kr abundances are discrepant and were once highly controversial. These discrepancies appear to have been not so much resolved as forgotten. Xenon was not detected on Venus. Upper limits were reported for the two most abundant xenon isotopes 129Xe and 132Xe. From the limited data it is not possible to tell whether Venus's affinities lie with the solar wind, or with the chondrites, with Earth, or with none of the above. Modern spacecraft mass spectrometers are at least 100-fold more sensitive to noble gases. Sending such an instrument to Venus may be the last best hope for decrypting what Earth's noble gases have been trying to tell us.

  7. Mineralogical, chemical composition and distribution of rare earth elements in clay-rich sediments from Southeastern Nigeria

    NASA Astrophysics Data System (ADS)

    Odoma, A. N.; Obaje, N. G.; Omada, J. I.; Idakwo, S. O.; Erbacher, J.

    2015-02-01

    Cretaceous claystone sediments from Enugu, Southeastern, Nigeria were analyzed for their mineralogy and chemistry. Major minerals are quartz and kaolinite while montmorillonite is in minor quantity. The sediments are silica-rich, but showed low values of Al, Fe, Sc and Cr. The values of the chemical index of alteration (CIA) ranged from 89.9 to 94.5 and the values of chemical index of weathering (CIW) ranged from 95.1 to 98.9. Low contents of the alkali and alkali earth elements (Na, K, Mg, Al, Ca) of the clay-rich sediments suggest a relatively more intense weathering of source area. Depleted Ba, Rb, Ca, and Mg suggest that they were probably flushed out by water during sedimentation. The mineralogical composition, REE contents, and elemental ratios in the sediments suggest a provenance from mainly felsic rocks, with only minor contributions from basic sources. Despite intense weathering the REE, Th, and Sc remained in the clays suggesting that they were immobile.

  8. Partitioning and Leaching Behavior of Actinides and Rare Earth Elements in a Zirconolite- Bearing Hydrothermal Vein System

    SciTech Connect

    Payne, Timothy E.; Hart, Kaye P.; Lumpkin, Gregory R.; McGlinn, Peter J.; Giere, Reto

    2007-07-01

    Chemical extraction techniques and scanning electron microscopy were used to study the distribution and behavior of actinides and rare earth elements (REE) in hydrothermal veins at Adamello (Italy). The six samples discussed in this paper were from the phlogopite zone, which is one of the major vein zones. The samples were similar in their bulk chemical composition, mineralogy, and leaching behavior of major elements (determined by extraction with 9 M HCl). However, there were major differences in the extractability of REE and actinides. The most significant influence on the leaching characteristics appears to be the amounts of U, Th and REE incorporated in resistant host phases (zirconolite and titanite) rather than readily leached phases (such as apatite). Uranium and Th are very highly enriched in zirconolite grains. Actinides were more readily leached from samples with a higher content of U and Th, relative to the amount of zirconium. The results show that REE and actinides present in chemically resistant host minerals can be retained under aggressive leaching conditions. (authors)

  9. Interpreting the effect of CO2-induced ocean acidification on elemental partitioning in biogenic carbonates within the framework of Rayleigh fractionation

    NASA Astrophysics Data System (ADS)

    Gilmore, R. E.; Eagle, R.; Ries, J. B.; Tripati, A. K.

    2013-05-01

    The elemental composition of calcium carbonate (CaCO3) precipitated by marine invertebrates varies with the physico-chemical properties of seawater, and is thus used for reconstructing past oceanic conditions, including temperature, pH, and seawater composition. Previous studies have used a Rayleigh fractionation model to interpret elemental partitioning within a range of calcitic and aragonitic organisms, including foraminifera and corals. We present elemental ratios for 18 species of calcareous marine invertebrates, including echinoids, corals, bivalves, gastropods, calcifying algae, crustacea, and serpulid worms, which were reared at CO2-induced aragonite saturation states (±SD) of 2.5 (±0.4), 2.0 (±0.4), 1.5 (±0.3), and 0.7 (±0.2). Importantly, specimens were cultured simultaneously at the same temperature and in seawater sourced from the same reservoir, allowing comparison amongst taxa without regard to native water conditions. A combination of Inductively Coupled Plasma Mass Spectrometry (ICPMS) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) were used to determine the elemental ratios. We interpret the partitioning of strontium, magnesium, barium, manganese, boron, lithium and uranium within the biogenic carbonates of these 18 invertebrates, along with data from the literature for foraminifera and coccolithophores raised under varying pCO2 and temperature conditions, within a Rayleigh fractionation framework. Application of a Rayleigh model to these systems requires constraints on elemental partitioning into inorganic CaCO3. Our survey of the literature shows that there are limited data for some elements (e.g., Mn) and that, for others (e.g., Sr, Mg), there are a wide range of values reported for a given element. Given this uncertainty, we examine the impact that varying the nominal inorganic partition coefficient has on Rayleigh-derived estimates of calcium-utilization during calcification. The elements examined in this study have different chemical and ionic properties (atomic mass, ionic radius, charge), and these properties impact the frequency that an element is incorporated into the CaCO3 lattice. A Rayleigh model allows us to determine at what point during calcification an element is assimilated into the CaCO3 lattice: whether it is incorporated even when there is abundant calcium in solution, or not incorporated until calcium is nearly depleted. The effect of CO2- and temperature-induced changes in calcification rate on element partitioning in these organisms will be examined to determine if these biogenic calcification systems conform to a Rayleigh model.

  10. Hydroxylamine hydrochloride-acetic acid-soluble and -insoluble fractions of pelagic sediment: Readsorption revisited

    USGS Publications Warehouse

    Piper, D.Z.; Wandless, G.A.

    1992-01-01

    The extraction of the rare earth elements (REE) from deep-ocean pelagic sediment, using hydroxylamine hydrochloride-acetic acid, leads to the separation of approximately 70% of the bulk REE content into the soluble fraction and 30% into the insoluble fraction. The REE pattern of the soluble fraction, i.e., the content of REE normalized to average shale on an element-by-element basis and plotted against atomic number, resembles the pattern for seawater, whereas the pattern, as well as the absolute concentrations, in the insoluble fraction resembles the North American shale composite. These results preclude significant readsorption of the REE by the insoluble phases during the leaching procedure.

  11. Visible Light Driven Photoelectrodes Made of Earth Abundant Elements for Water Photoelectrolysis

    NASA Astrophysics Data System (ADS)

    Huang, Qiang

    With the aim of creating a clean and sustainable energy supply, the direct use of solar energy to produce chemical energy has been pursued for many years. Particularly, the photoelectrolysis of water to generate hydrogen by semiconductor photoelectrodes has attracted great attention because of its advantage of using only water and sunlight, both of which are widely distributed, as raw materials. The earth abundant and visible light absorbing materials are promising for this application for the advantages of easy access and high theoretical solar to hydrogen conversion efficiency. In this thesis, the cadmium sulfide based and copper oxide based photoelectrodes were fabricated and characterized to determine their potential for photoelectrolysis. As one of the semiconductors with relatively narrow band gap, CdS (2.4eV) has a conduction band edge more negative than the water reduction potential level and a valence band edge more positive than the water oxidation potential level, enabling n-type CdS and p-type CdS as good candidates for photoanode and photocathode respectively. CdS thin film with thickness around 2mum was deposited onto Mo back contact on glass, which formed ohmic contact with CdS. The as-prepared CdS was intrinsic n-type due to the easy formation of sulfur vacancies and it was converted to p-type by the controlled thermal diffusion of copper atoms which substituted cadmium to produce acceptor state. The optimal Cu doping level for the interest of water photoelectrolysis was found to be at 5.4% concentration. Cu2O with band gap of 2.0eV is another attracting competitor for the photoelectrode among the metal-oxide semiconductors. Both thin film and highly aligned nanowire arrays Cu2O were prepared by thermal oxidation of Cu film and Cu nanowires on Au substrates synthesized by electrodeposition. Cu2O was found to be p-type because of the copper vacancies. The photocurrent of the Cu2O nanowires photocathode was found to be twice that of the Cu2O film, and the bare Cu2O photocathode suffered from a significant photo-induced reductive decomposition. By modifying the surface of the Cu2O nanowires with protecting layers of CuO and TiO2, direct contact of Cu2O with the electrolyte was avoided, and the Cu2O/CuO/TiO2 coaxial nanocable structures were found to gain 74% higher photocurrent and 4.5 times higher stability. Furthermore, the co-catalysts were also used to modify the photoelectrode surface to reduce the water splitting overpotentials by facilitating the transfer of the photo-induced carriers to the electrolyte. Cobalt based co-catalysts, both the Co2+ and Co3O4 thin film, enhanced the stability of the intrinsic n-CdS photoanode. The Pt modification of CdS:Cu, effectively eliminating the large transient photocurrent, enhanced the photocurrent and stability and positively shifted the onset potential of the cathodic photocurrent by 90 mV, and the hydrogen evolution from the p-type CdS:Cu/Pt photocathode was observed for the first time. This thesis not only studied the water photoelectrolysis potentials of CdS and Cu2O, but also presented general methods to prevent photocorrosion and enhance photo-activity, which could be also applied to other visible light responsive and earth abundant materials to enlarge the range of material choice for solar water splitting

  12. Separation of Bk(IV) and Ce(IV) from trivalent transplutonium and rare-earth elements on ion exchangers in solutions of sulfuric acid

    SciTech Connect

    Guseva, L.I.; Stepushkina, V.V.

    1988-05-01

    The behavior of Am, Cm, Bk, Cf, Es, Ce, Eu, and Pr on anion exchangers and cation exchangers mixed with PbO/sub 2/ in solutions of sulfuric acid has been investigated. A significant difference between the distribution coefficients of Bk and Ce, on the one hand, and the remaining transplutonium elements and rare-earth elements, on the other hand, which has been attributed to the oxidation of the first two elements to the tetravalent state, has been discovered. Methods for the preconcentration and separation of Bk(IV) and Ce(IV) from the other transplutonium and rare-earth element son anion exchangers in 0.01-0.25 M H/sub 2/SO/sub 4/ solutions and on cation exchangers in 0.75-1.0 M H/sub 2/SO/sub 4/ solutions have been proposed.

  13. Rare earth element patterns as correlation tools and tectonic indicators for the Paleogene Dillon Volcanics, southwestern Montana

    SciTech Connect

    McDowell, R.J.; Fritz, W.J.; Ghazi, A.M. . Dept. of Geology)

    1993-04-01

    The Dillon Volcanics of the Paleogene Renova Formation consist of epiclastic, pyroclastic, and volcanic rocks. The latter are composed of alkaline and transitional basalts and rhyolites. Major and trace element variation diagrams indicate that both rock types had a similar parent magma source, and that the rhyolites were mainly derived from a basaltic parent magma. This is confirmed by very similar rare earth element (REE) patterns. The REE patterns are typical of continental rift zone volcanics, and indicate that bimodal rift zone volcanism occurred in a back-arc setting 30 m.y. before basin-and-range extension. Subsequent normal faulting, combined with Neogene erosion, has separated the dillon Volcanics into isolated outcrops that cannot be accurately correlated in the field. Major and trace element compositional trends are not good correlation tools, but chondrite-normalized REE patterns are almost parallel for the rhyolites and can be used to correlate now-isolated outcrops. REE patterns for the basalts do not show the same degree of similarity, but their patterns do indicate a common magmatic source. REE patterns for continental rift settings typically show enrichment in light REE's, reflecting derivation from a light REE-enriched mantle source such as sub-continental lithosphere. As eruption of the Dillon volcanics was partly contemporaneous with arc volcanism related to the Laramide orogeny, the sub-continental lithosphere may have been enriched in light REE's bu subduction zone fluids derived from the down-going Farallon plate. However, it might not be possible to distinguish continental rift zone volcanics from continental back-arc basin volcanics. The authors favor the latter model because of the chronologic and geographic relationship of the dillon Volcanics with nearby continental arc volcanic fields.

  14. Trace and rare earth elemental variation in Arabian sea sediments through a transect across the oxygen minimum zone

    SciTech Connect

    Nath, B.N.; Rao, B.R.; Rao, C.M.; Bau, M.

    1997-06-01

    We have determined the calcium carbonate (CaCO{sub 3}), organic carbon (C{sub org}), trace element, and rare earth element (REE) composition of surface sediments collected from a transect on the central western continental shelf and slope of India in the Eastern Arabian Sea. The transect samples across the oxygen minimum zone (OMZ) allows us to compare the relative abundances of trace elements and REEs in the sediments beneath and beyond the OMZ. Shale-normalized REE patterns, La{sub n}/Yb{sub n} ratios, and Eu/Eu* anamolies indicate that the sediments in the study area are either derived from the adjoining Archaean land masses or from distal Indus source. Sediment deposited in the OMZ have high U values from 3.6 to 8.1 ppm, with their U{sub excess} (of that can be supplied by continental particles) values ranging between 82-91% of the total U, indicating that the U may be precipitated as U{sup +4} in the reducing conditions of OMZ. Sediments deposited beneath the intense OMZ (<0.2 mL/L) and away from the OMZ (1-2 mL/L) show slight negative Ce anomalies, with no significant differences between these two sets of sediments. The Ce/Ce*{sub shale} values are poorly related to U and C{sub org} which are indicators of suboxic bottom waters. Normative calculations suggest that two sources, namely, terrestrial and seawater (terrestrial > seawater) contribute to the total Ce anomaly of the sediments. The Ce anomaly values of the calculated seawater derived component are similar to the anomalies reported for other coastal waters and the oxygenated surface waters of the Arabian Sea and do not show any correspondence to the lowered redox state of the overlying water, probably due to the redirection of dissolved Ce into the oxic deeper water. 103 refs., 6 figs., 3 tabs.

  15. Investigation of the separation of scandium and rare earth elements from red mud by use of reversed-phase HPLC.

    PubMed

    Tsakanika, Lambrini V; Ochsenkühn-Petropoulou, Maria Th; Mendrinos, Leonidas N

    2004-07-01

    A chromatographic method has been developed for separation and determination of scandium (Sc) and rare earth elements (REEs) in samples from a red mud (RM)-utilization process. Reversed-phase high-performance liquid chromatography (RP-HPLC) with post-column derivatization using 4-(2-pyridylazo)-resorcinol (PAR) and UV-visible detection at 520 nm was tested using different gradient elution profiles and pH values to optimize separation and recovery, primarily for Sc but also for yttrium and the individual lanthanides, from iron present in the samples. The separation was performed in less than 20 min by use of a mobile phase gradient. The concentration of alpha-hydroxyisobutyric acid ( alpha-HIBA), as eluent, was altered from 0.06 to 0.4 mol L(-1) (pH 3.7) and 0.01 mol L(-1) sodium salt n-octane sulfonic acid (OS) was used as modifier. Very low detection limits in the nanogram range and a good resolution for Sc and REEs except for Y/Dy were achieved. Before application of the method to the red mud samples and to the corresponding bauxites, Sc and REEs were leached from red mud with 0.6 mol L(-1) HNO(3) and mostly separated, as a group, from the main elements by ion exchange/selective elution (6 mol L(-1) HNO(3)) in accordance with a pilot-plant process developed in this laboratory. After evaporation of the eluent to dryness the extracted elements were re-dissolved in the mobile phase. By use of this chromatographic method Sc, which is the most expensive of the elements investigated and occurs in economically interesting concentrations in red mud, could be separated not only from co-existing Fe but also from Y/Dy, Yb, Er, Ho, Gd, Eu, Sm, Nd, Pr, Ce and La. All the elements investigated were individually recovered. Their recoveries were found to be nearly quantitative. PMID:15221192

  16. Chemo-dynamical deuterium fractionation in the early solar nebula: The origin of water on Earth and in asteroids and comets

    E-print Network

    Albertsson, T; Henning, Th

    2014-01-01

    Formation and evolution of water in the Solar System and the origin of water on Earth constitute one of the most interesting questions in astronomy. The prevailing hypothesis for the origin of water on Earth is by delivery through water-rich small Solar system bodies. In this paper, the isotopic and chemical evolution of water during the early history of the solar nebula, before the onset of planetesimal formation, is studied. A gas-grain chemical model that includes multiply-deuterated species and nuclear spin-states is combined with a steady-state solar nebula model. To calculate initial abundances, we simulated 1 Myr of evolution of a cold and dark TMC1-like prestellar core. Two time-dependent chemical models of the solar nebula are calculated over 1 Myr: (1) a laminar model and (2) a model with 2D turbulent mixing. We find that the radial outward increase of the H2O D/H ratio is shallower in the chemo-dynamical nebular model compared to the laminar model. This is related to more efficient de-fractionation...

  17. The rare earth elements in municipal solid waste incinerators ash and promising tools for their prospecting.

    PubMed

    Funari, Valerio; Bokhari, Syed Nadeem Hussain; Vigliotti, Luigi; Meisel, Thomas; Braga, Roberto

    2016-01-15

    Bottom and fly ashes from Municipal Solid Waste Incinerators (MSWI) are hazardous products that present concern for their safe management. An attractive option to reduce their impact both on the environment and the financial commitment is turning MSWI ashes into secondary raw materials. In this study we present the REE content and distribution of bottom and fly ashes from MSWI after a highly effective digestion method and samples analysis by ICP-MS. The chondrite-normalised REE patterns of MSWI bottom and fly ash are comparable with that of crustal averages, suggesting a main geogenic source. Deviations from typical crustal pattern (e.g., Eu, Tb) disclose a contribution of likely anthropogenic provenance. The correlation with major elements indicates possible sources for REE and facilitates a preliminary resource assessment. Moreover, magnetic susceptibility measurements can be a useful prospecting method in urban ores made of MSWI ashes. The relationship between REE and some influencing parameters (e.g., Pricing Influence Factor) emphasises the importance of MSWI ash as alternative source of REE and the need of further efforts for REE recovery and purification from low concentrations but high flows waste. PMID:26414924

  18. Insights into early Earth from the Pt-Re-Os isotope and highly siderophile element abundance systematics of Barberton komatiites

    NASA Astrophysics Data System (ADS)

    Puchtel, Igor S.; Walker, Richard J.; Touboul, Mathieu; Nisbet, Euan G.; Byerly, Gary R.

    2014-01-01

    Highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundance and Pt-Re-Os isotopic data are reported for well-preserved komatiites from the Komati and Weltevreden Formations of the Barberton Greenstone Belt in South Africa. The Re-Os data for whole-rock samples and olivine and chromite separates define isochrons with ages of 3484 ± 38 and 3263 ± 12 Ma for the Komati and Weltevreden systems, respectively. The respective initial 187Os/188Os = 0.10335 ± 15 (?187Os = +0.34 ± 0.15) and 0.10442 ± 4 (?187Os = -0.14 ± 0.04) are well within the range defined by chondritic meteorites. When considered together with the Re-Os data for late Archean komatiite systems, these data indicate that the mantle sources of most Archean komatiites evolved with essentially uniform long-term Re/Os that is well within the chondritic range. By contrast, the initial 186Os/188Os = 0.1198283 ± 9 (?186Os = -0.12 ± 0.08) and 0.1198330 ± 8 (?186Os = +0.22 ± 0.07) for the Komati and Weltevreden systems, respectively, are outside of known chondritic evolution paths, indicating that the mantle sources of these two komatiite systems evolved with fractionated time-integrated Pt/Os. The new 186,187Os isotopic data for these early Archean komatiite systems, combined with published 142,143Nd and 176Hf isotopic data for these systems, are consistent with formation and long-term isolation of deep-seated mantle domains with fractionated time-integrated Sm/Nd, Lu/Hf, and Pt/Os ratios, at ca. 4400 Ma. These domains may have been generated as a result of late-stage crystallization of a primordial magma ocean involving Mg-perovskite, Ca-perovskite and Pt-alloys acting as the fractionating phases. The inferred fractionated mantle domains were sampled by the early Archean komatiites, but were largely mixed away by 2.7 Ga, as evidenced by uniform time-integrated Sm/Nd, Lu/Hf, and Pt/Os ratios inferred for the sources of most late Archean komatiite systems. The calculated total Pt + Pd abundances present in the sources of the early Archean komatiite systems fall only 7-14% short of those present in estimates for the modern primitive mantle. These are also within the range of the total Pt + Pd abundances present in the sources of late Archean komatiite systems, indicating little change in the HSE abundances in the Archean mantle between 3.5 and 2.7 Ga. The new HSE data for the early Archean komatiite systems may implicate late accretion of HSE to the mantle prior to completion of crystallization of a final terrestrial magma ocean, followed by sluggish mixing of diverse, post-magma ocean domains characterized by variably fractionated lithophile element and HSE abundances.

  19. Chemical Exchange Between the Core and the Convecting Mantle of the Earth: Evidence from Highly Siderophile Elements (HSE)

    NASA Astrophysics Data System (ADS)

    Schmidt, G.; Palme, H.; Kratz, K. L.

    1995-09-01

    Core formation is a major physical and chemical event in the evolution of a differentiated planet. The core is the dominant repository of HSE in the Earth. Element ratios of HSE in peridotites provide insights into the accretion processes of the Earth and the effect of core formation. Depletion of HSE in the Earth's mantle results from core formation. Refractory siderophile elements are about a factor of > 100 depleted in the Earth's mantle compared to CI carbonaceous chondrites. Nevertheless, the concentrations of PGE, Re and Au (7.1 +/- 0.8 x 10^-3 CI chondrite abundances) are higher than would be expected from metal-silicate partitioning during core formation [1]. Several different explanations have been suggested to explain the low absolute abundances of these elements. (1) Os, Re, Ir, Ru, Rh, Pd, Pt, and Au were added with a late chondritic veneer containing less than 1% of a CI component [2-9]. (2) Insufficient core formation, i.e. some metallic Fe-Ni was retained in the upper mantle during core formation [10]. (3) Disequilibrium during core formation; Segregation of metal from the upper mantle in later stages of accretion was so rapid that equilibrium was not attained [4,11,12]. (4) There was continuous formation of the core during accretion; Equilibrium between sinking metal grains and a molten magma ocean at high temperatures (3000-3500 K) [13]. (5) Increase in silicate/metal partition coefficients by pressure, temperature, or high f(O2) [5,14]; Solution of FeO in the core raises the f(O2) conditions at the core-mantle interface sufficiently to increase the equilibrium concentrations of the siderophile elements in the mantle [15]. Studies of mantle-derived samples such as massif peridotites and peridotite xenoliths provide direct information on the nature and composition of the upper mantle. Massive peridotitic rocks from Zabargad island (Red Sea), Lanzo (Italy), Ronda (Spain) and peridotitic xenoliths from Mongolia were analysed for Os, Re, Ir, Ru, Rh, Pd, and Au with a slightly modified neutron activation analysis in combination with a NiS extraction method [16]. All samples (except peridotitic xenoliths) have essentially unfractionated patterns (except Pd/Ir) despite significant variations in absolute abundances [17]. Os/Re ratios from massive peridotitic rocks from Zabargad are chondritic. Peridotitic xenoliths generally have Os/Re-ratios much higher than the chondritic ratio [2]. The Pd/Ir ratios from all studied peridotites are approximately two times and the Rh/Ir ratios are approximately 1.5 times higher than the chondritic ratio of 1.21 and 0.29, respectively. This is in qualitative agreement with estimates of Pd and Ir in primitive undepleted mantle [1]. The non-chondritic Pd/Ir and Rh/Ir ratios is either the result of Pd and Rh addition or these elements are not quantitatively removed from the mantle in the process of core formation [10]. Extrapolation of experimentally determined palladium and iridium metal/silicate partition coefficients to 3500 K are 3.8x10^3 and 2x10^8, respectively [18,19]. The observed non-chondritic ratio of Ir to Pd in the upper mantle is in qualitative agreement with experimentally determined metal/silicate partition coefficients for Ir and Pd. This could support recent speculation on the possibility of chemical exchange between the outer liquid shell of the core and the convecting mantle of the Earth. Acknowledgements. This work was supported by DFG. References: [1] Morgan J. W. (1986) JGR, 91, 12375-12387. [2] Morgan J. W. et al. (1981) Tectonophys., 75, 47-67. [3] Anders E. (1968) Acc. Chem. Res., 1, 289-298. [4] Turekian K. K. and Clark S. P. (1969) EPSL, 6, 346-348. [5] Kimura K. et al. (1974) GCA, 38, 683-701. [6] Ganapathy R. and Anders E. (1974) Proc. LPSC. [7] Chou C.-L. (1978) Proc. LPSC 9th, 219-230. [8] Jagoutz E. et al. (1979) Proc. LPSC 10th, 2031-2050. [9] Wanke H. (1981) Philos. Trans. R. Soc. London, A303, 287-302. [10] Jones J. H. and Drake M. J. (1986) Nature, 322, 221-228. [11] Ringwood A. E. (1966) GCA, 30, 41-104. [12] Morgan J. W. and Lovering J. F.

  20. The principal rare earth elements deposits of the United States-A summary of domestic deposits and a global perspective

    USGS Publications Warehouse

    Long, Keith R.; Van Gosen, Bradley S.; Foley, Nora K.; Cordier, Daniel

    2010-01-01

    The rare earth elements (REE) are fifteen elements with atomic numbers 57 through 71, from lanthanum to lutetium ('lanthanides'), plus yttrium (39), which is chemically similar to the lanthanide elements and thus typically included with the rare earth elements. Although industrial demand for these elements is relatively small in tonnage terms, they are essential for a diverse and expanding array of high-technology applications. REE-containing magnets, metal alloys for batteries and light-weight structures, and phosphors are essential for many current and emerging alternative energy technologies, such as electric vehicles, energy-efficient lighting, and wind power. REE are also critical for a number of key defense systems and other advanced materials. Section 843 of the National Defense Authorization Act for Fiscal Year 2010, Public Law 111-84, directs the Comptroller General to complete a report on REE materials in the defense supply chain. The Office of Industrial Policy, in collaboration with other U.S. Government agencies, has initiated (in addition to this report) a detailed study of REE. This latter study will assess the Department of Defense's use of REE, as well as the status and security of domestic and global supply chains. That study will also address vulnerabilities in the supply chain and recommend ways to mitigate any potential risks of supply disruption. To help conduct this study, the Office of Industrial Policy asked the U.S. Geological Survey (USGS) to report on domestic REE reserves and resources in a global context. To this end, the enclosed report is the initial USGS contribution to assessing and summarizing the domestic REE resources in a global perspective. In 2009, the Mineral Resources Program of the USGS organized a new project under the title Minerals at Risk and For Emerging Technologies in order to evaluate mineral resource and supply issues of rare metals that are of increasing importance to the national economy. Leaders and members of this project, with the assistance of the USGS National Minerals Information Center, prepared the enclosed USGS report on domestic REE resources. The USGS Mineral Resources Program has investigated domestic and selected foreign REE resources for many decades, and this report summarizes what has been learned from this research. The USGS National Minerals Information Center (formerly Minerals Information Team) has monitored global production, trade, and resources for an equally long period and is the principal source of statistics used in this report. The objective of this study is to provide a nontechnical overview of domestic reserves and resources of REE and possibilities for utilizing those resources. At the present time, the United States obtains its REE raw materials from foreign sources, almost exclusively from China. Import dependence upon a single country raises serious issues of supply security. In a global context, domestic REE resources are modest and of uncertain value; hence, available resources in traditional trading partners (such as Canada and Australia) are of great interest for diversifying sources of supply. This report restates basic geologic facts about REE relevant to assessing security of supply, followed by a review of current United States consumption and imports of REE, current knowledge of domestic resources, and possibilities for future domestic production. Further detail follows in a deposit-by-deposit review of the most significant domestic REE deposits (see index map). Necessary steps to develop domestic resources are discussed in a separate section, leading into a review of current domestic exploration and a discussion of the value of a future national mineral resource assessment of REE. The report also includes an overview of known global REE resources and discusses the reliability of alternative foreign sources of REE.

  1. Rare earth elements in apatite: Uptake from H{sub 2}O-bearing phosphate-fluoride melts and the role of volatile components

    SciTech Connect

    Fleet, M.E.; Pan, Yuanming

    1997-11-01

    The partitioning of rare earth elements (REEs) between fluorapatite (FAp) and H{sub 2}O- bearing phosphate-fluoride melts has been studied at about 700 and 800{degrees}C and 0.10-0.15 GPa. REE uptake patterns, i.e., plots of D(REE:FAp/melt), are convex upwards and peak near Nd for single-REE substituted FAp at minor (0.03-0.25 wt% REE{sub 2}O{sub 3}) abundances, and binary (LREE + HREE)-substituted FAp, and hexa-REE-substituted FAp at minor to major (0.25-7.8 wt% REE{sub 2}O{sub 3}) abundances. Partition coefficients for minor abundances of REE and depolymerized phosphate melts are about 5, 8, and 1 for La, Nd, and Lu, respectively and broadly comparable to those for early fluorapatite in the fractionation of melts of basaltic composition. The Ca2 site exerts marked control on the selectivity of apatite for REE because it preferentially incorporates LREE and its effective size varies with substitution of the A-site volatile anion component (F, Cl, OH). Using simple crystal-chemical arguments, melt(or fluid)-normalized REE patterns are predicted to peak near Nd for fluorapatite and be more LREE-enriched for chlorapatite. These predictions are consistent with data from natural rocks and laboratory experiments. The wide variation in D(REE:apatite/melt) in nature (from <1 for whitlockite-bearing lunar rocks to about 100 for evolved alkalic rocks) is attributed largely to the influence of the volatile components. 49 refs., 8 figs., 3 tabs.

  2. Polymer monolithic capillary microextraction combined on-line with inductively coupled plasma MS for the determination of trace rare earth elements in biological samples.

    PubMed

    Zhang, Lin; Chen, Beibei; He, Man; Hu, Bin

    2013-07-01

    A rapid and sensitive method based on polymer monolithic capillary microextraction combined on-line with microconcentric nebulization inductively coupled plasma MS has been developed for the determination of trace/ultratrace rare earth elements in biological samples. For this purpose, the iminodiacetic acid modified poly(glycidyl methacrylate-trimethylolpropane trimethacrylate) monolithic capillary was prepared and characterized by SEM and FTIR spectroscopy. Factors affecting the extraction efficiency, such as sample pH, sample flow rate, sample/eluent volume, and coexisting ions were investigated in detail. Under the optimal conditions, the LODs for rare earth elements were in the range of 0.08 (Er) to 0.97 ng/L (Nd) with a sampling frequency of 8.5 h(-1), and the RSDs were between 1.5% (Sm) and 7.4% (Nd) (c = 20 ng/L, n = 7). The proposed method was successfully applied to the analysis of trace/ultratrace rare earth elements in human urine and serum samples, and the recoveries for the spiked samples were in the range of 82-105%. The developed method was simple, rapid, sensitive, and favorable for the analysis of trace/ultratrace rare earth elements in biological samples with limited sample volume. PMID:23625586

  3. Determination of Barium and selected rare-earth elements in geological materials employing a HpGe detector by radioisotope excited x-ray fluorescence

    SciTech Connect

    LaBrecque, J.J.; Preiss, I.L.

    1984-01-01

    The laterite material (geological) from Cerro Impacto was first studied by air radiometric techniques in the 1970's and was found to have an abnormally high radioactive background. Further studies showed this deposit to be rich in thorium, columbium, barium and rare-earth elements (mostly La, Ce, Pr and Nd). A similar work has been reported for the analysis of Brazil's lateritic material from Morro do Ferro to determine elemental compositions (including barium and rare-earth elements) and its relationship to the mobilization of thorium from the deposit using a Co-57 radioisotope source. The objective of this work was to develop an analytical method to determine barium and rare-earth element present in Venezuelan lateritic material from Cerro Impacto. We have employed a method before, employing a Si(Li) detector, but due to the low detection efficiencies in the rare-earth K-lines region (about 30 KeV - 40 KeV), we have decided to study the improvement in sensitivities and detection limits using an hyperpure germanium detector.

  4. Geochemical and mineralogical constraints on the distribution and enrichment of the rare earth elements during pedogenesis and tropical weathering

    NASA Astrophysics Data System (ADS)

    Hardy, Liam; Smith, Martin; Moles, Norman; Marsellos, Antonios

    2015-04-01

    Current European manufacturing relies heavily on imports from the USA & China for unprocessed rare earth elements (REEs) and rare earth oxides (REOs). It has been suggested that the EU holds viable reserves of REEs that, with adequate research, could satisfy 10% of EU industrial demand, by the recycling of mine waste from bauxite production (red muds) alone (Deady, E. (BGS), 2014). Focus has been turned to the potential for Mount Weld type laterite deposits being exploited in the EU, but limited exploration and understanding of EU laterite (& paleo laterite) formations currently makes them unattractive to investment. Although previously researched, the full range of factors influencing the transition of rare earth (primarily lanthanide series, Y & Sc) elements between mineral and clay phases in allochthonous soils, saprolites and laterites is not fully understood, especially in present and Paleo-European environments (Herrington, Boni, Skarpelis, & Large, 2007) (Deady, E. (BGS), 2014) but several deposits globally are suggested to have formed at economically viable concentrations due to this secondary remobilisation & transition from mineral to clay phase and subsequent seasonal leaching and evaporation system, to form depositional buffer zones other than the soil base. (Hoatson, Jaireth, & Miezitis, 2011) (Berger, Janots, Gnos, Frei, & Bernier, 2014). This project intends to use new techniques in sequential extractions, ICP-MS, Quantitative XRD & SEM analysis to expand current knowledge around lateritic & allochtonous ore forming, & weathering processes. Heavy REE content and mineralogical variations in clays will be examined, with examples from a selection of profiles across Southern Europe (and potentially paleo soils from Scandinavia) to define the main influencing factors on REE concentration. Are the specific sites enriched simply by the nature of their source rock (protolith), by the soil formation (pedogenesis), or by biogenic & meteorological factors? These results will then be applied in targeted, environmentally focused exploration projects, and perhaps enhance techniques used industrially for the extraction of HREEs, for less environmentally damaging production in sensitive areas (with current research sites within national parks in Italy and Portugal; and in areas where it is believed more attention should be paid to environmental preservation, including Central Turkey and Southern China). It is hypothesised that: HREE content in tropical laterite formations is due primarily to the source rock's mineralogy, although it's distribution is a result of slower genesis and leaching as opposed to more common biogenetic pedogenesis. It is suggested this distribution initially forms banded horizontal enrichment zones according to protolith, but eventual separation of heavy and light REEs is controlled by clay-surface (the protolith's weathering style), solvent type, fluctuation and availability. It may be found, as in Fe-Ni laterite resources globally (Herrington, Boni, Skarpelis, & Large, 2007) (Eliopoulos, 2000), that high initial bedrock concentrations of REEs are not necessarily required if prolonged weathering continues to concentrate these elements/minerals over longer periods (although this has been found inversely in certain Turkish bauxites (Karadag?, Peli, Ary, & Ayhan, 2008)). Regardless of eventual concentrations, identifying the argillic phase and the time scales required for clay REE hosting clay formation may broaden the European search for supergene enrichments to REE hosting marine shales, mineral sands and other sedimentary formations that have been long-term- weathered without major displacement.

  5. Evolution of U fractionation processes through geologic time : consequences for the variation of U deposit types from Early Earth to Present

    NASA Astrophysics Data System (ADS)

    Cuney, M.

    2009-12-01

    U deposits are known at nearly all stages of the geological cycle, but are not known prior to 2.95 Ga. Also, U deposit types vary greatly from Mesoarchean to Present. Most of these changes through time can be attributed to major modifications in the geodynamic evolution of the Earth, in magmatic fractionation processes, in the composition of the Atmosphere and in the nature of life. The first U-rich granites able to crystallize uraninite, appeared at about 3.1 Ga. They correspond to the most fractionated terms of high-K calcalkaline suites, resulting from crystal fractionation of magmas possibly derived from melting of mantle wedges enriched in K, U, Th. Highly fractionated peraluminous leucogranites, able to crystallize uraninite, appeared at about 2.6 Ga. Erosion of these two granite types led to the detrital accumulation of uraninite that formed the first U deposits on Earth: the Quartz Pebble Conglomerates from 2.95 to 2.4 Ga. From 2.3 Ga onwards, uprise of oxygen level in the atmosphere led to the oxidation of U(IV) to U(VI), U transport in solution, and exuberant development of marine algae in epicontinental platform sediments. From 2.3 to 1.8 Ga large amounts of U, previously accumulated as U(IV) minerals, were dissolved and trapped preferentially in passive margin settings, in organic-rich sediments, and which led to the formation of the world’s largest Paleoproterozoic U provinces, e.g. : the Wollaston belt, Canada and the Cahill Formation, Australia. During and after the worldwide 2.1-1.75 Ga orogenic events, responsible for the formation of the Nuna supercontinent, U trapped in these formations was the source for several types of mineralization: (i) metamorphosed U-mineralized graphitic schists, calcsilicates and meta-arkoses, (ii) diagenetic-hydrothermal remobilization with the formation of the first deposits related to redox processes at 2.0 Ga (Oklo, Gabon), (iii) partial melting of U-rich metasediments forming the uraninite disseminations in pegmatoids (Charlebois, Canada), (iv) hydrothermal remobilization in veins (Beaverlodge, Canada) at about 1.75 Ga, and (v) U mineralization related to Na-metasomatism (Lagoa Real, Brazil ; Central Ukraine). After 1.75 Ga, a long period of tectonic quiescence occurred on the Earth, and large intracontinental basins, comprising at their base thick oxidized siliciclastic sequences were formed in many parts of the Nuna. In the Athabasca (Canada) and Kombolgie (Australia) basins, the siliciclastic sediments represented huge aquitards for sodic brines derived from overlying evaporites. The brines became calcic when infiltrated into the basement and leached U dominantly from Paleoproterozoic epicontinental sediments, their anatectic derivatives and high-K-U granites, to form the unconformity related U deposits. By the end of Silurian, with the apparition of land plants, deposits hosted by continental to marginal marine sandstone (roll front, tabular, tectono-lithologic, paleovalleys) became widespread. The largest volcanic related U-deposits are mostly known during the Mesozoic and calcrete are only known during late Caenozoic to Quaternary, but this may by due to the non preservation from erosion of such deposits formed at very shallow levels.

  6. Distribution of trace and major elements in the -180 + 75 ?m and -75 ?m fractions of the sandveld regolith in northwest Ngamiland, Botswana

    NASA Astrophysics Data System (ADS)

    Chatupa, J. C.; Direng, B. B.

    2000-04-01

    An orientation survey was undertaken in northwest Ngamiland to evaluate, among other criteria, an optimum size fraction for trace element analysis in the Kalahari sandveld regolith samples for a regional geochemical mapping project in the area. The most prominent geomorphological features of the region are the longitudinal rolling sand dunes and floodplain sediments adjacent to the unique, mid-continent Okavango Delta. Most of the dune sands were deposited in the Late Quaternary, and they show evidence of both pluvial and and environments. Presently the a lab dunes support varied shrub/grass vegetation with intermittent tree cover. Extensive forest fires have affected the region for generations, and the occurrences of remnants of large trees indicate that the region may have also supported large forests at some stage. The sandveld regolith comprises 70% quartz sand (-1000 + 63 ?m) and 10-20% silt/clay (< 63 ?m) material. There are no size variations between material from dune crests, dune depressions and down the soil profile to a depth of a metre. The process of regolith formation is relatively young and dynamic, being widely churned by a variety of boring animals, termites, ants and other insects. Hence no distinct zonation of soil horizons in the top 100 cm of the soil catena were observed. Remarkably, the significant proportion of the silt/clay fraction in the regolith indicates progressive weathering and possible deposition of precipitates. Trace element contents are invariably enhanced in the fine fractions, a characteristic widely observed elsewhere in residual soils. On the Xaxa-Cheracheraha traverse Zn values range from 2 to 98 ppm (mean 9 ppm); Pb varies from 1 to 101 ppm (mean 27 ppm) and Cu from 0 to 18 ppm (mean 5 ppm) in the -75 ?m fraction. Contents in the -180 + 75 ?m are, however, significantly lower than in the fine fractions. The variations in element concentrations along each of the orientation survey traverses at Qangwa-Nokaneng, Nxaunxau-Qurube and Nxaunxau-Ghane, in the coarse and fine fractions, generally remain sympathetic, showing that the enhanced values in the fines are a result of secondary dispersion, rather than mere compositional differences in the sandveld regolith.

  7. Effect of Rare Earth Elements (Er, Ho) on Semi-Metallic Materials (ScN) in an Applied Electric Field

    NASA Technical Reports Server (NTRS)

    Kim, Hyunjung; Park, Yeonjoon; King, Glen C.; Lee, Kunik; Choi, Sang H.

    2012-01-01

    The development of materials and fabrication technology for field-controlled spectrally active optics is essential for applications such as membrane optics, filters for LIDARs, windows for sensors, telescopes, spectroscopes, cameras and flat-panel displays. The dopants of rare earth elements, in a host of optical systems, create a number of absorption and emission band structures and can easily be incorporated into many high quality crystalline and amorphous hosts. In wide band-gap semiconductors like ScN, the existing deep levels can capture or emit the mobile charges, and can be ionized with the loss or capture of the carriers which are the fundamental basis of concept for smart optic materials. The band gap shrinkage or splitting with dopants supports the possibility of this concept. In the present work, a semi-metallic material (ScN) was doped with rare earth elements (Er, Ho) and tested under an applied electric field to characterize spectral and refractive index shifts by either Stark or Zeeman Effect. These effects can be verified using the UV-Vis spectroscopy, the Hall Effect measurement and the ellipsometric spectroscopy. The optical band gaps of ScN doped with Er and doped with Ho were experimentally estimated as 2.33eV and 2.24eV ( 0.2eV) respectively. This is less than that of undoped ScN (2.5 0.2eV). The red-shifted absorption onset is a direct evidence for the decrease of band gap energy (Eg), and the broadening of valence band states is attributable to the doping cases. A decrease in refractive index with an applied field was observed as a small shift in absorption coefficient using a variable angle spectroscopic ellipsometer. In the presence of an electric field, mobile carriers are redistributed within the space charge region (SCR) to produce this electro-refractive effect. The shift in refractive index is also affected by the density and location of deep potential wells within the SCR. In addition, the microstructure change was observed by a TEM analysis. These results give an insight for future applications for the field-controlled spectrally active material systems.

  8. TerraFERMA: The Transparent Finite Element Rapid Model Assembler for multi-physics problems in the solid Earth sciences

    NASA Astrophysics Data System (ADS)

    Spiegelman, M. W.; Wilson, C. R.; Van Keken, P. E.

    2013-12-01

    We announce the release of a new software infrastructure, TerraFERMA, the Transparent Finite Element Rapid Model Assembler for the exploration and solution of coupled multi-physics problems. The design of TerraFERMA is driven by two overarching computational needs in Earth sciences. The first is the need for increased flexibility in both problem description and solution strategies for coupled problems where small changes in model assumptions can often lead to dramatic changes in physical behavior. The second is the need for software and models that are more transparent so that results can be verified, reproduced and modified in a manner such that the best ideas in computation and earth science can be more easily shared and reused. TerraFERMA leverages three advanced open-source libraries for scientific computation that provide high level problem description (FEniCS), composable solvers for coupled multi-physics problems (PETSc) and a science neutral options handling system (SPuD) that allows the hierarchical management of all model options. TerraFERMA integrates these libraries into an easier to use interface that organizes the scientific and computational choices required in a model into a single options file, from which a custom compiled application is generated and run. Because all models share the same infrastructure, models become more reusable and reproducible. TerraFERMA inherits much of its functionality from the underlying libraries. It currently solves partial differential equations (PDE) using finite element methods on simplicial meshes of triangles (2D) and tetrahedra (3D). The software is particularly well suited for non-linear problems with complex coupling between components. We demonstrate the design and utility of TerraFERMA through examples of thermal convection and magma dynamics. TerraFERMA has been tested successfully against over 45 benchmark problems from 7 publications in incompressible and compressible convection, magmatic solitary waves and Stokes flow with free surfaces. We have been using it extensively for research in basic magma dynamics, fluid flow in subduction zones and reactive cracking in poro-elastic materials. TerraFERMA is open-source and available as a git repository at bitbucket.org/tferma/tferma and through CIG. Instability of a 1-D magmatic solitary wave to spherical 3D waves calculated using TerraFERMA

  9. Ages, rare-earth element enrichment, and petrogenesis of tholeiitic and alkalic basalts from Kahoolawe Island, Hawaii

    USGS Publications Warehouse

    Fodor, R.V.; Frey, F.A.; Bauer, G.R.; Clague, D.A.

    1992-01-01

    Kahoolawe Island, Hawaii (18??11 km), is a basaltic shield volcano with caldera-filling lavas, seven identified postshield vents, and at least two occurrences of apparent rejuvenated-stage eruptive. We examined 42 samples that represent all stages of Kahoolawe volcano stratigraphy for their petrography, whole-rock major-and trace-element contents, mineral compositions, and K-Ar ages. The two oldest shield samples have an average age of 1.34??0.08 Ma, and four postshield samples (3 are alkalic) average 1.15??0.03 Ma; ages of 1.08 and 0.99 Ma for two additional tholeiitic samples probably are minimum ages. Whole-rock major- and trace-element and mineral compositions of Kahoolawe shield and caldera-fill laves are generally similar to the lavas forming Kilauea and Mauna Loa tholeiitic shields, but in detail, Kahoolawe shield lavas have distinctive compositions. An unusual aspect of many postshield Ka-hoolawe lavas is anomalously high REE and Y abundances (up to 200 ppm La and 175 ppm Y) and negative Ce anomalies. These enrichments reflect surficial processes, where weathering and soil development promoted REE-Y transport at the weathering front. Major element abundances (MgO, 10-6 wt.%) for shield and caldera-fill basalts are consistent with fractionation of ol+px+pl in frequently replenished magma reservoirs. In general, tholeiitic basalts erupted from late vents are higher in SiO2 than the shield lavas, and temporal differences in parental magma compositions are the likely explanation. Alkalic basalts that erupted from vents are comparable in composition to those at other Hawaiian volcanoes. Trace-element abundance ratios indicate that alkalic basalts represent either relatively lower degrees of melting of the shield source or a distinct source. Apparent rejuvenated-stage basalts (i.e., emplaced after substantial Kahoolawe erosion) are tholeiitic, unlike the rejuvenated-stages at other Hawaiian volcanoes (alkalic). Kahoolawe, like several other Hawaiian volcanoes, has intercalated tholeiitic and alkalic basalts in the postshield stage, but it is the only volcano that appears to have produced tholeiitic rejuvenated-stage lavas. ?? 1992 Springer-Verlag.

  10. Fractionation of airborne particulate-bound elements in haze-fog episode and associated health risks in a megacity of southeast China.

    PubMed

    Li, Huiming; Wang, Qin'geng; Shao, Min; Wang, Jinhua; Wang, Cheng; Sun, Yixuan; Qian, Xin; Wu, Hongfei; Yang, Meng; Li, Fengying

    2016-01-01

    Haze caused by high particulate matter loadings is an important environmental issue. PM2.5 was collected in Nanjing, China, during a severe haze-fog event and clear periods. The particulate-bound elements were chemically fractionated using sequential extractions. The average PM2.5 concentration was 3.4 times higher during haze-fog (96-518 ?g/m(3)) than non-haze fog periods (49-142 ?g/m(3)). Nearly all elements showed significantly higher concentrations during haze-fog than non-haze fog periods. Zn, As, Pb, Cd, Mo and Cu were considered to have higher bioavailability and enrichment degree in the atmosphere. Highly bioavailable fractions of elements were associated with high temperatures. The integrated carcinogenic risk for two possible scenarios to individuals exposed to metals was higher than the accepted criterion of 10(-6), whereas noncarcinogenic risk was lower than the safe level of 1. Residents of a city burdened with haze will incur health risks caused by exposure to airborne metals. PMID:26552535

  11. Measuring Gap Fraction, Element Clumping Index and LAI in Sierra Forest Stands Using a Full-Waveform Ground-Based Lidar

    NASA Technical Reports Server (NTRS)

    Zhao, Feng; Strahler, Alan H.; Crystal L. Schaaf; Yao, Tian; Yang, Xiaoyuan; Wang, Zhuosen; Schull, Mitchell A.; Roman, Miguel O.; Woodcock, Curtis E.; Olofsson, Pontus; Ni-Meister, Wenge; Jupp, David L. B.; Lovell, Jenny L.; Culvenor, Darius S.; Newnham, Glenn J.

    2012-01-01

    The Echidna Validation Instrument (EVI), a ground-based, near-infrared (1064 nm) scanning lidar, provides gap fraction measurements, element clumping index measurements, effective leaf area index (LAIe) and leaf area index (LAI) measurements that are statistically similar to those from hemispherical photos. In this research, a new method integrating the range dimension is presented for retrieving element clumping index using a unique series of images of gap probability (Pgap) with range from EVI. From these images, we identified connected gap components and found the approximate physical, rather than angular, size of connected gap component. We conducted trials at 30 plots within six conifer stands of varying height and stocking densities in the Sierra National Forest, CA, in August 2008. The element clumping index measurements retrieved from EVI Pgap image series for the hinge angle region are highly consistent (R2=0.866) with those of hemispherical photos. Furthermore, the information contained in connected gap component size profiles does account for the difference between our method and gap-size distribution theory based method, suggesting a new perspective to measure element clumping index with EVI Pgap image series and also a potential advantage of three dimensional Lidar data for element clumping index retrieval. Therefore further exploration is required for better characterization of clumped condition from EVI Pgap image series.

  12. Critical Zone Weathering and Your Smartphone: Understanding How Mineral Decomposition and Colloid Redistribution Can Generate Rare Earth Element Deposits

    NASA Astrophysics Data System (ADS)

    Bern, C.; Foley, N.

    2014-12-01

    Rare earth elements (REE's) are crucial in the manufacture of smartphones and many other high tech devices. Increasing global demand and relatively narrow geographic sourcing have promoted interest in understanding REE deposit genesis and distribution. Highly weathered, clay-hosted, ion-exchange type deposits in southern China are the source of much of the world's production of the more valuable heavy REEs. Such deposits form as REE-bearing minerals weather and REEs released to solution in ionic form are retained by negatively charged exchange sites on clay minerals. We are investigating the potential for ion-exchange REE deposits in the Piedmont of the southeastern United States, where slow erosion rates have preserved thick (up to 20 m) regolith, as required for such deposits. The Liberty Hill pluton outcrops as coarse-grained biotite-amphibole granite and quartz monzonite over nearly 400 km2 in South Carolina, and has an age of 305 Ma (new SHRIMP ion microprobe zircon age). In weathered profiles over the pluton, ion-exchangeable REE content ranges from 8 to 580 ppm and accounts for 2 to 80% of bulk REE content. Elemental and heavy mineral distributions suggest the wide ranging differences in leachability may be attributable to the amount and distribution of resistant REE-bearing phases (e.g., monazite) relative to more easily weathered phases (e.g., allanite) in the parent granite. The REEs show little mobility within the regolith, indicating the effectiveness of the ion-exchange retention mechanism. In contrast, vertical redistribution of colloidal material shows maximum accumulations at ~1 m depth, as traced by the newly developed dual-phase (colloids vs. solution) mass balance model. The contrast suggests redistributed colloidal material has minimal influence on REE mobilization or retention. Conditions and processes necessary for ion-exchange REE deposit development exist in the Piedmont, but their presence will depend upon favorable parent rock mineralogy.

  13. A major glacial-interglacial change in aeolian dust composition inferred from Rare Earth Elements in Antarctic ice

    NASA Astrophysics Data System (ADS)

    Gabrielli, Paolo; Wegner, Anna; Petit, Jean Robert; Delmonte, Barbara; De Deckker, Patrick; Gaspari, Vania; Fischer, Hubertus; Ruth, Urs; Kriews, Michael; Boutron, Claude; Cescon, Paolo; Barbante, Carlo

    2010-01-01

    We present the first Rare Earth Elements (REE) concentration record determined in 294 sections of an Antarctic ice core (EPICA Dome C), covering a period from 2.9 to 33.7 kyr BP. REE allow a detailed quantitative evaluation of aeolian dust composition because of the large number of variables (i.e. 14 elements). REE concentrations match the particulate dust concentration profile over this period and show a homogeneous crustal-like composition during the last glacial stage (LGS), with only a slight enrichment in medium REE. This signature is consistent with the persistent fallout of a mixture of dust from heterogeneous sources located in different areas or within the same region (e.g. South America). Starting at ˜15 kyr BP, there was a major change in dust composition, the variable character of which persisted throughout the Holocene. This varying signature may highlight the alternation of single dust contributions from different sources during the Holocene. We observe that the frequent changes in REE composition at the onset of the Holocene (10-13.5 kyr BP) are linked to dust size and in turn to wind strength and/or the path of the atmospheric trajectory. This may indicate that atmospheric circulation dictated the composition of the dust fallout to East Antarctica at that time. Although the dust concentrations remained fairly low, a notable return towards more glacial dust characteristics is recorded between 7.5 and 8.3 kyr BP. This happened concomitantly with a widespread cold event around 8 kyr BP that was 400-600 years long and suggests a moderate reactivation of the dust emission from the same potential source areas of the LGS.

  14. Investigation of Rare-Earth Elements in the Atmosphere of the roAp Star HD 134214: Nd II, Nd III, and Gd II Lines

    NASA Astrophysics Data System (ADS)

    Mykhailytskaya, N. G.

    2015-12-01

    High-resolution spectra are used to investigate the abundance of rare-earth elements (REE) in the atmosphere of the magnetic, rapidly oscillating, chemically peculiar (roAp) star HD134214. The neodymium abundance is investigated using the lines of neodymium in the first and second ionization states. Disruption of ionization equilibrium REE (mismatch of the contents determined according to the lines of singly and doubly ionized atoms) is found in the atmosphere of the roAp star. Excess abundance of the rare-earth elements (relative to the Sun) is found. The results of an abundance analysis of REE and some other elements are presented. The modulus and the components Br /Bm of the magnetic field are determined.

  15. Separation of Bk(IV) and Ce(IV) from trivalent transplutonium and rare earth elements on ion exchange resins in solutions of sulfuric acid

    SciTech Connect

    Guseva, L.I.; Stepushkina, V.V.

    1987-11-01

    Th behavior of Am, Cm, Bk, Cf, Es, Ce, Eu, and Pr on an anion exchange resin and a cation exchange resin in a mixture with PbO/sub 2/ was investigated in sulfuric acid solutions. A substantial difference was detected in the distribution coefficients of Bk and Ce, on the one hand, and the remaining transplutonium and rare earth elements, on the other, associated with oxidation of the first two elements to the tetravalent state. Methods are proposed for the concentration and separation of Bk(IV) and Ce(IV) from the other transplutonium and rare earth elements on an anion exchange resin in solution of 0.01-0.25 M H/sub 2/SO/sub 4/ and a cation exchange resin in 0.75-1.0 M H/sub 2/SO/sub 4/.

  16. Investigation of Rare-Earth Elements in the Atmosphere of the roAp Star HD 134214: Nd II, Nd III, and Gd II Lines

    NASA Astrophysics Data System (ADS)

    Mykhailytskaya, N. G.

    2015-11-01

    High-resolution spectra are used to investigate the abundance of rare-earth elements (REE) in the atmosphere of the magnetic, rapidly oscillating, chemically peculiar (roAp) star HD134214. The neodymium abundance is investigated using the lines of neodymium in the first and second ionization states. Disruption of ionization equilibrium REE (mismatch of the contents determined according to the lines of singly and doubly ionized atoms) is found in the atmosphere of the roAp star. Excess abundance of the rare-earth elements (relative to the Sun) is found. The results of an abundance analysis of REE and some other elements are presented. The modulus and the components Br /Bm of the magnetic field are determined.

  17. Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

    NASA Astrophysics Data System (ADS)

    Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

    2012-03-01

    For reconstructing environmental change in terrestrial realms the geochemistry of fossil bioapatite in bones and teeth is among the most promising applications. This study demonstrates that alkaline earth elements in enamel of Hippopotamids, in particular Ba and Sr are tracers for water provenance and hydrochemistry. The studied specimens are molar teeth from Hippopotamids found in modern and fossil lacustrine settings of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by ca. two orders of magnitude for Ba (120-9336 ?g g-1) as well as for Sr (9-2150 ?g g-1). Concentration variations in enamel are partly induced during post-mortem alteration and during amelogenesis, but the major contribution originates from the variable water chemistry in the habitats of the Hippopotamids which is dominated by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3-1.5. These elements are well correlated with MgO and Na2O in single specimens, thus suggesting that their distribution is determined by a common, single process. Presuming that the shape of the tooth is established at the end of the secretion process and apatite composition is in equilibrium with the enamel fluid, the maturation process can be modeled by closed system Rayleigh crystallization. Enamel from many Hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores, but the compositions extend well into the levels of plants and carnivores. Within enamel from single specimens these element ratios covary and provide a specific fingerprint of the Hippopotamid habitat. All specimens together, however, define subparallel trends with different Ba/Sr ranging from 0.1 to 3. This ratio varies on spatial and temporal scales and traces provenance signals as well as the fractionation of the elements in the hydrological cycle. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic or Archean crustal rocks as the ultimate sources of Sr and Ba. The provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from about 2 to 0.5. This trend can be correlated with changes in climate from humid to arid in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water. The most plausible explanation is that with time, Ba mobility decreased relative to that of Sr. This can arise if preferential adsorption of Ba to clay and Fe-oxide-hydroxide is related to increasing aridification. Additionally, weathering solutions and lake water can become increasingly alkaline and barite becomes stable. In this case, Ba will be preferentially deposited on the watershed of Lake Albert and rivers with low Ba/Sr will feed the habitats of the Hippopotamids.

  18. Early depositional history of metalliferous sediments in the Atlantis II Deep of the Red Sea: Evidence from rare earth element geochemistry

    NASA Astrophysics Data System (ADS)

    Laurila, Tea E.; Hannington, Mark D.; Petersen, Sven; Garbe-Schönberg, Dieter

    2014-02-01

    The Atlantis II Deep is a brine-filled depression on the slowly spreading Red Sea rift axis. It is by far the largest deposit of hydrothermally precipitated metals on the present ocean floor and the only known modern deposit that is analogous to laminated Fe-rich chemical sediments, such as banded iron formation (BIF). The brine pool at the bottom of the Atlantis II Deep creates an environment where most of the hydrothermally sourced elements can be dispersed and deposited over an area of ˜60 km2. We analyzed the rare earth element concentrations in 100 small-volume samples from 9 cores in different parts of the Atlantis II Deep to better understand the origins of different types of metalliferous sediments (detrital, proximal hydrothermal and distal hydrothermal). Our results agree with earlier studies based on larger bulk samples that show the composition of the major depositional units is related to major changes in the location and intensity of hydrothermal activity and the amount of hydrothermal versus background sedimentation. In this paper, we address the origins of chemically distinct laminae (down to sub-millimeter) that correspond to ˜annual deposition. REE patterns clearly reflect 3 different sources (e.g., detrital, scavenging, direct hydrothermal input). Detrital REE that are delivered to the Deep from outside account for most of the REE in the sediments of the Atlantis II Deep, similar to BIF, and are unaffected by fractionation due to hydrothermal processes during deposition and diagenesis. Fe- and Mn-(oxy)hydroxides that form at the anoxic-oxic boundary scavenge REE from the brine pool as they settle. The Fe-(oxy)hydroxides contain a larger proportion of REE from seawater than any other sediment-type and also scavenge REE from pore waters after deposition. In contrast, the Mn-(oxy)hydroxides dissolve before deposition and thus function as transporting agents between seawater and the brine. However, there is little evidence for direct seawater influence in the REE geochemistry of the sediments (e.g., Y/Ho ratio). Non-ferrous sulfides form proximal to the hydrothermal vent source and inherit an hydrothermal REE pattern. The total REE content of the presently forming Fe-(oxy)hydroxides is very low due to limited input of REE into the brine. The largest proportion of non-detrital REE appears to have been deposited early in the history of the basin from an initial brine pool that was relatively enriched in REE, followed by a change in REE chemistry in later sediments. Similar abrupt changes in the REE chemistry of ancient chemical sediments may record similar processes, including changes in local basin evolution and input of REE from different sources.

  19. Rare earth element distribution in >400 °C hot hydrothermal fluids from 5°S, MAR: The role of anhydrite in controlling highly variable distribution patterns

    NASA Astrophysics Data System (ADS)

    Schmidt, K.; Garbe-Schönberg, D.; Bau, M.; Koschinsky, A.

    2010-07-01

    Two submarine hydrothermal vent fields at 5°S, Mid-Atlantic Ridge (MAR) - Turtle Pits and Comfortless Cove - emanate vapor-phase fluids at conditions close to the critical point of seawater (407 °C, 298 bars). In this study, the concentration and distribution of rare earth element (REE) and yttrium (Y) has been investigated. Independent of the major element composition, the fluids display a strong temporal variability of their REE + Y concentrations and relative distributions at different time scales of minutes to years. Chondrite-normalized distributions range from common fluid patterns with light REE enrichment relative to the heavy REE, accompanied by positive Eu anomalies (type I), to strongly REE + Y enriched patterns with a concave-downward distribution with a maximum enrichment of Sm and weakly positive or even negative Eu anomalies (type II). The larger the sum of REE, the smaller Ce CN/Yb CN and Eu/Eu?. We also observed a strong variability in fluid flow and changing fluid temperatures, correlating with the compositional variability. As evident by the positive correlation of total REE, Ca, and Sr concentrations in Turtle Pits and Comfortless Cove fluids, precipitation/dissolution of hydrothermal anhydrite controls the variability in REE concentrations and distributions in these fluids and the transformation of one fluid type to the other. The variable distribution of REE can be explained by the accumulation of particulate anhydrite (with concave-downward REE distribution and negative Eu anomaly) into a fluid with common REE distribution (type I), followed by the modification of the REE fluid signature due to dissolution of incorporated anhydrite. A second model, in which the type II fluids represent a primary REE reaction zone fluid pattern, which is variably modified by precipitation of anhydrite, can also explain the observed correlations of total REE, fractionation of LREE/HREE and size of Eu anomaly as well as Ca, Sr. The emanation of such a fluid may be favored in a young hydrothermal system in its high-activity phase with short migration paths and limited exchange with secondary minerals. However, this model is not as well constrained as the other and requires further investigations. The strongly variable REE fluid signature is restricted to the very hot, actively phase-separating hydrothermal systems Turtle Pits and Comfortless Cove at 5°S and has not been observed at the neighboring Red Lion vent field, which continuously emanates 350 °C hot fluid and displays a stable REE distribution (type I).

  20. Subcellular distribution of rare earth elements and characterization of their binding species in a newly discovered hyperaccumulator Pronephrium simplex.

    PubMed

    Lai, Ying; Wang, Qiuquan; Yang, Limin; Huang, Benli

    2006-08-15

    Subcellular distribution of rare earth elements (REEs, including 14 lanthanides and yttrium) in a newly discovered REE hyperaccumulator, Pronephrium simplex (P. simplex), was determined by a chemical sequence extraction followed by ICP-MS analysis. Results showed that most REEs are associated with cell wall and proteins, and REEs concentration in the proteins, 2899.5mugg(-1), is much higher than those in the cell wall; in the chloroplast of P. simplex, REEs distribute almost equally in chloroplast membrane and thylakoid, while most REEs in the thylakoid are binding with photosystem II (PS II); a new REE-binding peptide in the lamina of P. simplex, which can accumulate REEs up to 3000mugg(-1) and has higher affinity with light REEs, was characterized, indicating that its molecular mass is 5073Da, and may have beta-sheet structure; isoelectrofocusing electrophoretic photograph indicated that it is acidic peptide with IP of 3.7. Such information should be useful for understanding of both the storage and physiological role of REEs in P. simplex and further studies on the phytoremediation of REEs contaminated environments. PMID:18970723

  1. Cyanex 923 as the extractant in a rare earth element impurity analysis of high-purity cerium oxide.

    PubMed

    Duan, Taicheng; Li, Hongfei; Kang, JianZhen; Chen, Hangting

    2004-06-01

    In this work, the feasibility of employing Cyanex 923 as an extractant into the non-cerium REE (rare earth elements) impurity analysis of high-purity cerium oxide was investigated. Through investigations on the choice of the extraction medium, the optimium extraction acidity, matrix Ce4+ effect on the non-cerium REE ion extraction, the optimium extractant concentration and suitable extracting time, and oscillation strengh, it was found that when the phase ratio was at 1:1 and the acicidity was about 2% H2SO4, by gently shaking by hand for about 2 min, 10 mL of 30% Cyanex 923 could not extract even for a 20 ng amount of non-cerium REE3+ ions. However, the extraction efficiency for Ce4+ of 100 mg total amount under the same conditions was about 96%, indicating that a 25-fold preconcentration factor could be achieved. Thus, it was concluded that Cyanex 923 could be used in a REE impurity analysis of 99.9999% or so pure cerium oxide for primary sepapation to elimilate matrix-induced interferences encountered in an ICP-MS (inductively coupled plasma mass spectroscopy) determination. PMID:15228111

  2. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    SciTech Connect

    Li, Jiawei; Huo, Juntao; Chang, Chuntao E-mail: dujun@nimte.ac.cn; Du, Juan E-mail: dujun@nimte.ac.cn; Man, Qikui; Wang, Xinmin; Li, Run-Wei; Law, Jiayan

    2014-08-14

    The effects of heavy rare earth (RE) additions on the Curie temperature (T{sub C}) and magnetocaloric effect of the Fe-RE-B-Nb (RE?=?Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune T{sub C} in a large temperature range of 120?K without significantly decreasing the magnetic entropy change (?S{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ?S{sub M} and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd{sub 5}Ge{sub 1.9}Si{sub 2}Fe{sub 0.1}. The tunable T{sub C} and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.

  3. Formation of carbonatite-related giant rare-earth-element deposits by the recycling of marine sediments

    PubMed Central

    Hou, Zengqian; Liu, Yan; Tian, Shihong; Yang, Zhiming; Xie, Yuling

    2015-01-01

    Carbonatite-associated rare-earth-element (REE) deposits are the most significant source of the world’s REEs; however, their genesis remains unclear. Here, we present new Sr-Nd-Pb and C-O isotopic data for Cenozoic carbonatite-hosted giant REE deposits in southwest China. These REE deposits are located along the western margin of the Yangtze Craton that experienced Proterozoic lithospheric accretion, and controlled by Cenozoic strike-slip faults related to Indo-Asian continental collision. The Cenozoic carbonatites were emplaced as stocks or dykes with associated syenites, and tend to be extremely enriched in Ba, Sr, and REEs and have high 87Sr/86Sr ratios (>0.7055). These carbonatites were likely formed by melting of the sub-continental lithospheric mantle (SCLM), which had been previously metasomatized by high-flux REE- and CO2-rich fluids derived from subducted marine sediments. The fertility of these carbonatites depends on the release of REEs from recycled marine sediments and on the intensity of metasomatic REE refertilization of the SCLM. We suggest that cratonic edges, particularly along ancient convergent margins, possess the optimal configuration for generating giant REE deposits; therefore, areas of metamorphic basement bounded or cut by translithospheric faults along cratonic edges have a high potential for such deposits. PMID:26035414

  4. Some Rare Earth Elements Analysis by Microwave Plasma Torch Coupled with the Linear Ion Trap Mass Spectrometry

    PubMed Central

    Xiong, Xiaohong; Jiang, Tao; Qi, Wenhao; Zuo, Jun; Yang, Meiling; Fei, Qiang; Xiao, Saijin; Yu, Aimin; Zhu, Zhiqiang; Chen, Huanwen

    2015-01-01

    A sensitive mass spectrometric analysis method based on the microwave plasma technique is developed for the fast detection of trace rare earth elements (REEs) in aqueous solution. The plasma was produced from a microwave plasma torch (MPT) under atmospheric pressure and was used as ambient ion source of a linear ion trap mass spectrometer (LTQ). Water samples were directly pneumatically nebulized to flow into the plasma through the central tube of MPT. For some REEs, the generated composite ions were detected in both positive and negative ion modes and further characterized in tandem mass spectrometry. Under the optimized conditions, the limit of detection (LOD) was at the level 0.1?ng/mL using MS2 procedure in negative mode. A single REE analysis can be completed within 2~3 minutes with the relative standard deviation ranging between 2.4% and 21.2% (six repeated measurements) for the 5 experimental runs. Moreover, the recovery rates of these REEs are between the range of 97.6%–122.1%. Two real samples have also been analyzed, including well and orange juice. These experimental data demonstrated that this method is a useful tool for the field analysis of REEs in water and can be used as an alternative supplement of ICP-MS. PMID:26421013

  5. Rare Earth Element Signatures of Early Diagenesis in Pore Waters at Methane-Seeps from Hydrate Ridge, off Oregon

    NASA Astrophysics Data System (ADS)

    Himmler, T.; Haley, B.; Torres, M. E.; Klinkhammer, G. P.; Bohrmann, G.; Peckmann, J.

    2010-12-01

    Rare earth element (REE) concentrations of pore waters from Beggiatoa covered sediments at methane-seeps on southern Hydrate Ridge were analyzed using ion-exchange chromatography. Pore water REE concentration significantly increase within the first 2 cm below seafloor compared to bottom water concentration. Below 2 cm a gradual decrease is observed, reaching bottom water REE concentrations at 5 cm. At this depth, pore water sulfate is completely consumed and converted to hydrogen-sulfide through sulfate reduction. Shale-normalized REE patterns show a linear light REE-depletion across the REE series. At 2 cm a distinct convex-shaped, light REE-depleted pattern with a positive cerium (Ce) anomaly is observed. All other samples reveal negative Ce anomalies. These findings suggest (1) an active REE-source immediately below the sediment-water interface, which might be related to the anaerobic oxidation of methane coupled to sulfate reduction at this depth (c.f. Boetius et al., 2000. A marine consortium apparently mediating anaerobic oxidation of methane. Nature 407, 623-626), and (2) REE-removal from pore waters probably caused by the uptake of REEs in authigenic minerals (e.g. carbonates, sulfides, barite).

  6. From the subtropics to the central equatorial Pacific Ocean: Neodymium isotopic composition and rare earth element concentration variations

    NASA Astrophysics Data System (ADS)

    Grenier, MéLanie; Jeandel, Catherine; Lacan, FrançOis; Vance, Derek; Venchiarutti, CéLia; Cros, Alexandre; Cravatte, Sophie

    2013-02-01

    Neodymium isotopic compositions (?Nd) and rare earth element (REE) concentrations were measured for filtered surface to deep waters (112 samples) in the Southern Tropical Pacific. The relatively detailed picture of these tracer distributions allowed us to refine the areas where oceanic ?Nd variations occur. ?Nd values increase for most of the water masses flowing from Samoa to the Solomon Sea and in the Papua New Guinea (PNG) area, as already observed. Furthermore, water masses arriving from the eastern equatorial Pacific (200-550 m depth) also revealed radiogenic values, possibly acquired in the vicinity of the South American coasts and Galapagos Islands. These ?Nd variations affect the whole water column. The most likely process causing such variations is "boundary exchange" between the numerous radiogenic slopes/margins located in this area and seawater flowing past. Dissolution of atmospheric deposition and/or diffuse streaming of volcanic ash are also suggested to explain the radiogenic ?Nd observed at the surface in the PNG area. Interestingly, a positive europium (Eu) anomaly characterizes the normalized REE patterns of most of the studied water masses. This anomaly is consistent with the REE patterns of sediment and rock samples that are potential sources for the local waters. Such consistency reinforces the hypothesis that lithogenic sources play a major role in the oceanic REE budget, thanks to "boundary exchange." The data set presented here is a good basis for further sampling that will be realized in the framework of the ongoing GEOTRACES program (www.geotraces.org).

  7. Formation of carbonatite-related giant rare-earth-element deposits by the recycling of marine sediments.

    PubMed

    Hou, Zengqian; Liu, Yan; Tian, Shihong; Yang, Zhiming; Xie, Yuling

    2015-01-01

    Carbonatite-associated rare-earth-element (REE) deposits are the most significant source of the world's REEs; however, their genesis remains unclear. Here, we present new Sr-Nd-Pb and C-O isotopic data for Cenozoic carbonatite-hosted giant REE deposits in southwest China. These REE deposits are located along the western margin of the Yangtze Craton that experienced Proterozoic lithospheric accretion, and controlled by Cenozoic strike-slip faults related to Indo-Asian continental collision. The Cenozoic carbonatites were emplaced as stocks or dykes with associated syenites, and tend to be extremely enriched in Ba, Sr, and REEs and have high (87)Sr/(86)Sr ratios (>0.7055). These carbonatites were likely formed by melting of the sub-continental lithospheric mantle (SCLM), which had been previously metasomatized by high-flux REE- and CO2-rich fluids derived from subducted marine sediments. The fertility of these carbonatites depends on the release of REEs from recycled marine sediments and on the intensity of metasomatic REE refertilization of the SCLM. We suggest that cratonic edges, particularly along ancient convergent margins, possess the optimal configuration for generating giant REE deposits; therefore, areas of metamorphic basement bounded or cut by translithospheric faults along cratonic edges have a high potential for such deposits. PMID:26035414

  8. Preliminary estimates of the quantities of rare-earth elements contained in selected products and in imports of semimanufactured products to the United States, 2010

    USGS Publications Warehouse

    Bleiwas, Donald I.; Gambogi, Joseph

    2013-01-01

    Rare-earth elements (REEs) are contained in a wide range of products of economic and strategic importance to the Nation. The REEs may or may not represent a significant component of that product by mass, value, or volume; however, in many cases, the embedded REEs are critical for the device’s function. Domestic sources of primary supply and the manufacturing facilities to produce products are inadequate to meet U.S. requirements; therefore, a significant percentage of the supply of REEs and the products that contain them are imported to the United States. In 2011, mines in China produced roughly 97 percent of the world’s supply of REEs, and the country’s production of these elements will likely dominate global supply until at least 2020. Preliminary estimates of the types and amount of rare-earth elements, reported as oxides, in semimanufactured form and the amounts used for electric vehicle batteries, catalytic converters, computers, and other applications were developed to provide a perspective on the Nation’s use of these elements. The amount of rare-earth metals recovered from recycling, remanufacturing, and reuse is negligible when the tonnage of products that contain REEs deposited in landfills and retained in storage is considered. Under favorable market conditions, the recovery of REEs from obsolete products could potentially displace a portion of the supply from primary sources.

  9. Micromorphological features of the fine earth and skeletal fractions of soils of West Antarctica in the areas of Russian Antarctic stations

    NASA Astrophysics Data System (ADS)

    Abakumov, E. V.; Gagarina, E. I.; Sapega, V. F.; Vlasov, D. Yu.

    2013-12-01

    Micromorphological features of the fine earth and skeletal fractions of soils of West Antarctica forming under different conditions of pedogenesis have been studied in the areas of Russian Antarctic stations. The processes of mineral weathering and alteration of rock fragments are more pronounced in the Subantarctic soils with better developed humification and immobilization of iron compounds under conditions of surface overmoistening. The biogenic accumulative processes in the soils of King George Island result in the appearance of initial forms of humic plasma that have not been detected in the Antarctic soils in the areas of the Russkaya and Leningradskaya stations. Humus films on mineral grains are present in the soils of King George Island, and organic plasmic material is present in the ornithogenic soils under penguin guano on Lindsey Island. High-latitude Antarctic soils may contain surface concentrations of organic matter; rock fragments are covered by iron oxides and soluble salts. The formation of amorphous organic plasma takes place in the ornithogenic soils of Lindsey Island. The microprobe analysis indicates the presence of local concentrations of organic matter and pedogenic compounds not only on the surface of rock fragments but also in the fissures inside them. This analysis has also proved the translocation of guano-derived organic substances inside rock fragments through a system of fissures in the soils of Lindsey Island and the development of a network of pores inside rock fragments in the soils of King George Island.

  10. Highly siderophile element systematics of the 3.3 Ga Weltevreden komatiites, South Africa: Implications for early Earth history

    NASA Astrophysics Data System (ADS)

    Connolly, Brian D.; Puchtel, Igor S.; Walker, Richard J.; Arevalo, Ricardo; Piccoli, Philip M.; Byerly, Gary; Robin-Popieul, Christophe; Arndt, Nick

    2011-11-01

    Highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundances, Re-Os isotopic systematics, and major-, minor-, and lithophile trace element abundances are determined for a suite of remarkably fresh komatiites from the Weltevreden Formation (Fm.) of the Barberton Greenstone Belt, South Africa. The komatiite lavas examined are calculated to have contained ca. 31% MgO upon emplacement, and are among the most MgO-rich lavas ever erupted onto Earth's surface. Based on the partitioning behavior of V, indicating reduced conditions of magma formation, as well as the low calculated H 2O abundance of ~ 0.02% in the mantle source, anhydrous melting for the Weltevreden Fm. komatiites is inferred. The high calculated liquidus temperatures of the emplaced komatiite lavas of ca. 1600 °C require an unusually hot (~ 1800 °C) mantle source, > 100 °C hotter than the ambient contemporaneous mantle. These observations are most consistent with formation of the Weltevreden komatiites via deep (~ 530 km) melting in a mantle plume. The Re-Os isotopic data for twelve whole-rock samples and an olivine separate define a precise Re-Os isochron age of 3266 ± 8 Ma (2? mean) and an initial 187Os/ 188Os of 0.10440 ± 5 (? 187Os = - 0.13 ± 0.05). The Re-Os data, coupled with the relatively high calculated HSE abundances in the mantle source totaling ~ 80% of those in modern Primitive Mantle (PM) estimates, indicate that at least some portions of the deep, early Archean mantle evolved with essentially chondritic Re/Os and absolute HSE abundances that are typical of the sources of late Archean komatiites. If the HSE budget of the terrestrial mantle was established via late accretion of several large planetesimals following the cessation of major chemical interaction between the core and the mantle, our data indicate that by 3.3 Ga, these materials were well homogenized within the mantle domains sampled by the Weltevreden komatiites and, by inference, within the mantle as a whole.

  11. Laboratory calibration and field testing of the Chemcatcher-Metal for trace levels of rare earth elements in estuarine waters.

    PubMed

    Petersen, Jördis; Pröfrock, Daniel; Paschke, Albrecht; Broekaert, Jose A C; Prange, Andreas

    2015-10-01

    Little knowledge is available about water concentrations of rare earth elements (REEs) in the marine environment. The direct measurement of REEs in coastal waters is a challenging task due to their ultra-low concentrations as well as the high salt content in the water samples. To quantify these elements at environmental concentrations (pg L(-1) to low ng L(-1)) in coastal waters, current analytical techniques are generally expensive and time consuming, and require complex chemical preconcentration procedures. Therefore, an integrative passive sampler was tested as a more economic alternative sampling approach for REE analysis. We used a Chemcatcher-Metal passive sampler consisting of a 3M Empore Chelating Disk as the receiving phase, as well as a cellulose acetate membrane as the diffusion-limiting layer. The effect of water turbulence and temperature on the uptake rates of REEs was analyzed during 14-day calibration experiments by a flow-through exposure tank system. The sampling rates were in the range of 0.42 mL h(-1) (13 °C; 0.25 m s(-1)) to 4.01 mL h(-1) (13 °C; 1 m s(-1)). Similar results were obtained for the different REEs under investigation. The water turbulence was the most important influence on uptake. The uptake rates were appropriate to ascertain time-weighted average concentrations of REEs during a field experiment in the Elbe Estuary near Cuxhaven Harbor (exposure time 4 weeks). REE concentrations were determined to be in the range 0.2 to 13.8 ng L(-1), where the highest concentrations were found for neodymium and samarium. In comparison, most of the spot samples measured along the Chemcatcher samples had REE concentrations below the limit of detection, in particular due to necessary dilution to minimize the analytical problems that arise with the high salt content in marine water samples. This study was among the first efforts to measure REE levels in the field using a passive sampling approach. Our results suggest that passive samplers could be an effective tool to monitor ultra-trace concentrations of REEs in coastal waters with high salt content. PMID:26062469

  12. Methodology Measuring Rare Earth Elements in High TDS Reservoir Brines Application as Natural Tracers in CCUS Studies

    NASA Astrophysics Data System (ADS)

    Smith, W.; Mcling, T. L.; Smith, R. W.; Neupane, H.

    2013-12-01

    In recent years rare earth elements (REE) have been demonstrated to be useful natural tracers for geochemical processes in aqueous environments. The application of REE's to carbon dioxide utilization and storage (CCUS) could provide researchers with a sensitive, inexpensive tool for tracking the movement of CO2 and displaced formation brines. By definition, geologic reservoirs that have been deemed suitable for carbon capture and storage contain formation brine with total dissolved solids (TDS) greater than 10,000 ppm and often these formation brines exceed 75,000 ppm TDS. This high TDS water makes it very difficult to measure REE, which typically occur at part per trillion concentrations. Critical to the use of REE for CCUS studies is the development of a procedure, which allows for the pre-concentration of REE's across a wide range of water quality. Additionally, due to the large number of samples that will need analysis, any developed procedure must be inexpensive, reproducible, and quick to implement. As part of the Big Sky Carbon Sequestration Project the INL's Center for Advance Energy Studies is developing REE pre-concentration procedures based on methods reported in the literature. While there are many REE pre-concentration procedures in the literature, our tests have shown these methods have difficulty at TDS greater than seawater (roughly 35,000 ppm TDS). Therefore, the ability to quantitatively measure REE's in formation brines with very high TDS has required the modification of an already developed procedure. After careful consideration and testing we selected methods modified after those described by Kingston et al., 1978 and Strachan et al., 1989 utilizing chelating media for very high TDS waters and ion-exchange media as detailed by Crock et al., 1984; Robinson et al., 1985; and Stetzenbach et al., 1994 for low TDS (<10,000 ppm TDS) waters. These modified procedures have been successfully tested in our laboratory and have proven effective in greatly reducing interfering monovalent and divalent cation concentrations (e.g. Ba) and enriching the REE up to 100X for analysis. The procedures are straightforward, inexpensive, and require little infrastructure, using only single chromatography columns with inexpensive, reusable, commercially available resins and wash chemicals. The procedures have been tested with synthetic brines and waters (up to 250,000 ppm TDS) and field water samples (up to 5,000 ppm TDS). Testing has produced data with REE capture efficiency exceeding 95%, while reducing interfering elements by more than 93%. Further method development and testing continues in preparation for brine analysis of waters from the Big Sky Carbon Sequestration Partnership's Kevin Dome Pilot Study and the University of Wyoming's Carbon Institutes Rock Springs Uplift.

  13. An algorithm to derive the fraction of photosynthetically active radiation absorbed by photosynthetic elements of the canopy (FAPAR(ps)) from eddy covariance flux tower data.

    PubMed

    Ogutu, Booker O; Dash, Jadunandan

    2013-01-01

    The fraction of absorbed photosynthetically active radiation (FAPAR) is a key vegetation biophysical variable in most production efficiency models (PEMs). Operational FAPAR products derived from satellite data do not distinguish between the fraction of photosynthetically active radiation (PAR) absorbed by nonphotosynthetic and photosynthetic components of vegetation canopy, which would result in errors in representation of the exact absorbed PAR utilized in photosynthesis. The possibility of deriving only the fraction of PAR absorbed by photosynthetic elements of the canopy (i.e. FAPAR(ps) ) was investigated. The approach adopted involved inversion of net ecosystem exchange data from eddy covariance measurements to calculate FAPAR(ps) . The derived FAPAR(ps) was then related to three vegetation indices (i.e. Normalized Difference Vegetation Index (NDVI), Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) and Enhanced Vegetation Index (EVI)) in an attempt to determine their potential as surrogates for FAPAR(ps) . Finally, the FAPAR(ps) was evaluated against two operational satellite data-derived FAPAR products (i.e. MODIS and CYCLOPES products). The maximum FAPAR(ps) from the inversion approach ranged between 0.6 and 0.8. The inversion approach also predicted site-specific Q??-modelled daytime respiration successfully (R² > 0.8). The vegetation indices were positively correlated (R² = 0.67-0.88) to the FAPAR(ps). Finally, the two operational FAPAR products overestimated the FAPAR(ps). This was attributed to the two products deriving FAPAR for the whole canopy rather than for only photosynthetic elements in the canopy. PMID:23173991

  14. Uptake and Effects of Six Rare Earth Elements (REEs) on Selected Native and Crop Species Growing in Contaminated Soils.

    PubMed

    Carpenter, David; Boutin, Céline; Allison, Jane E; Parsons, Jessica L; Ellis, Deanna M

    2015-01-01

    Rare earth elements (REEs) have become increasingly important metals used in modern technology. Processes including mining, oil refining, discarding of obsolete equipment containing REEs, and the use of REE-containing phosphate fertilizers may increase the likelihood of environmental contamination. However, there is a scarcity of information on the toxicity and accumulation of these metals to terrestrial primary producers in contaminated soils. The objective of this work was to assess the phytotoxicity and uptake from contaminated soil of six REEs (chloride forms of praseodymium, neodymium, samarium, terbium, dysprosium, and erbium) on three native plants (Asclepias syriaca L., Desmodium canadense (L.) DC., Panicum virgatum L.) and two crop species (Raphanus sativus L., Solanum lycopersicum L.) in separate dose-response experiments under growth chamber conditions. Limited effects of REEs were found on seed germination and speed of germination. Effects on aboveground and belowground biomass were more pronounced, especially for the three native species, which were always more sensitive than the crop species tested. Inhibition concentrations (IC25 and IC50) causing 25 or 50% reductions in plant biomass respectively, were measured. For the native species, the majority of aboveground biomass IC25s (11 out of 18) fell within 100 to 300 mg REE/kg dry soil. In comparison to the native species, IC25s for the crops were always greater than 400 mg REE/kg, with the majority of results (seven out of 12) falling above 700 mg REE/kg. IC50s were often not detected for the crops. Root biomass of native species was also affected at lower doses than in crops. REE uptake by plants was higher in the belowground parts than in the above-ground plant tissues. Results also revealed that chloride may have contributed to the sensitivity of the native species, Desmodium canadense, one of the most sensitive species studied. Nevertheless, these results demonstrated that phytotoxicity may be a concern in contaminated areas. PMID:26076480

  15. Factors that Influence the Price of Al, Cd, Co, Cu, Fe, Ni, Pb, Rare Earth Elements, and Zn

    USGS Publications Warehouse

    Papp, John F.; Bray, E. Lee; Edelstein, Daniel L.; Fenton, Michael D.; Guberman, David E.; Hedrick, James B.; Jorgenson, John D.; Kuck, Peter H.; Shedd, Kim B.; Tolcin, Amy C.

    2008-01-01

    This report is based on a presentation delivered at The 12th International Battery Materials Recycling Seminar, March 17-20, 2008, Fort Lauderdale, Fla., about the factors that influence prices for aluminum, cadmium, cobalt, copper, iron, lead, nickel, rare earth elements, and zinc. These are a diverse group of metals that are of interest to the battery recycling industry. Because the U.S. Geological Survey (USGS) closely monitors, yet neither buys nor sells, metal commodities, it is an unbiased source of metal price information and analysis. The authors used information about these and other metals collected and published by the USGS (U.S. production, trade, stocks, and prices and world production) and internationally (consumption and stocks by country) from industry organizations, because metal markets are influenced by activities and events over the entire globe. Long-term prices in this report, represented by unit values, were adjusted to 1998 constant dollars to remove the effects of inflation. A previous USGS study in this subject area was 'Economic Drivers of Mineral Supply' by Lorie A. Wagner, Daniel E. Sullivan, and John L. Sznopek (USGS Open File Report 02-335). By seeking a common cause for common behavior of prices among the various metal commodities, the authors found that major factors that influence prices of metal commodities were international events such as wars and recessions, and national events such as the dissolution of the Soviet Union in 1991 and economic growth in China, which started its open door policy in the 1970s but did not have significant market impact until the 1990s. Metal commodity prices also responded to commodity-specific events such as tariff or usage changes or mine strikes. It is shown that the prices of aluminum, cadmium, copper, iron, lead, nickel, and zinc are at historic highs, that world stocks are at (or near) historic lows, and that China's consumption of these metals had increased substantially, making it the world's leading consumer of these metals.

  16. Geophysical expression of a buried niobium and rare earth element deposit: the Elk Creek carbonatite, Nebraska, USA

    NASA Astrophysics Data System (ADS)

    Drenth, B.; Phillips, J. D.; Kass, A.; Krahenbuhl, R. A.

    2014-12-01

    The lower Paleozoic Elk Creek carbonatite is a 6-8 kilometer diameter intrusive complex buried under 200 meters of sedimentary rocks in southeastern Nebraska. It hosts the largest known niobium deposit in the U.S. and a rare earth element (REE) deposit. The carbonatite is composed of several lithologies, the relations of which are poorly understood. Niobium mineralization is most enriched within a magnetite beforsite unit, and REE oxides are concentrated in a barite beforsite unit. The carbonatite intrudes Proterozoic country rocks. A high-resolution airborne gravity gradient and magnetic survey was flown over the carbonatite in 2012. The carbonatite is associated with an annular vertical gravity gradient high with a subdued central low, and a central magnetic high surrounded by magnetic field values lower than those over the country rocks. Geophysical, borehole, and physical property data are combined for an interpretation of these signatures. The carbonatite is denser than the country rocks, explaining the gravity gradient high. Most carbonatite lithologies have weaker magnetic susceptibilities than those of the country rocks, explaining why the carbonatite produces a magnetic low at its margin. The primary source of the central magnetic high is interpreted to be mafic rocks that are strongly magnetized and are present in large volumes. Magnetite beforsite is very dense (mean density 3200 kg/m3) and strongly magnetized (median 0.073 SI magnetic susceptibility), producing a gravity gradient high and contributing to the aeromagnetic high. Barite beforsite has physical properties similar to most of the carbonatite volume, making it a poor geophysical target. Geophysical anomalies indicate the presence of dense and strongly magnetized rocks at depths below existing boreholes, either a large volume of magnetite beforsite or another unknown lithology. Studies are underway to investigate possible effects of alteration and magnetic remanence, and to better constrain the 3D distribution of magnetite beforsite.

  17. Uptake and Effects of Six Rare Earth Elements (REEs) on Selected Native and Crop Species Growing in Contaminated Soils

    PubMed Central

    Carpenter, David; Boutin, Céline; Allison, Jane E.; Parsons, Jessica L.; Ellis, Deanna M.

    2015-01-01

    Rare earth elements (REEs) have become increasingly important metals used in modern technology. Processes including mining, oil refining, discarding of obsolete equipment containing REEs, and the use of REE-containing phosphate fertilizers may increase the likelihood of environmental contamination. However, there is a scarcity of information on the toxicity and accumulation of these metals to terrestrial primary producers in contaminated soils. The objective of this work was to assess the phytotoxicity and uptake from contaminated soil of six REEs (chloride forms of praseodymium, neodymium, samarium, terbium, dysprosium, and erbium) on three native plants (Asclepias syriaca L., Desmodium canadense (L.) DC., Panicum virgatum L.) and two crop species (Raphanus sativus L., Solanum lycopersicum L.) in separate dose-response experiments under growth chamber conditions. Limited effects of REEs were found on seed germination and speed of germination. Effects on aboveground and belowground biomass were more pronounced, especially for the three native species, which were always more sensitive than the crop species tested. Inhibition concentrations (IC25 and IC50) causing 25 or 50% reductions in plant biomass respectively, were measured. For the native species, the majority of aboveground biomass IC25s (11 out of 18) fell within 100 to 300 mg REE/kg dry soil. In comparison to the native species, IC25s for the crops were always greater than 400 mg REE/kg, with the majority of results (seven out of 12) falling above 700 mg REE/kg. IC50s were often not detected for the crops. Root biomass of native species was also affected at lower doses than in crops. REE uptake by plants was higher in the belowground parts than in the above-ground plant tissues. Results also revealed that chloride may have contributed to the sensitivity of the native species, Desmodium canadense, one of the most sensitive species studied. Nevertheless, these results demonstrated that phytotoxicity may be a concern in contaminated areas. PMID:26076480

  18. South Pacific dissolved Nd isotope compositions and rare earth element distributions: Water mass mixing versus biogeochemical cycling

    NASA Astrophysics Data System (ADS)

    Molina-Kescher, Mario; Frank, Martin; Hathorne, Ed

    2014-02-01

    Despite its enormous extent and importance for global climate, the South Pacific has been poorly investigated in comparison to other regions with respect to chemical oceanography. Here we present the first detailed analysis of dissolved radiogenic Nd isotopes (?Nd) and rare earth elements (REEs) in intermediate and deep waters of the mid-latitude (˜40°S) South Pacific along a meridional transect between South America and New Zealand. The goal of our study is to gain better insight into the distribution and mixing of water masses in the South Pacific and to evaluate the validity of Nd isotopes as a water mass tracer in this remote region of the ocean. The results demonstrate that biogeochemical cycling (scavenging processes in the Eastern Equatorial Pacific) and release of LREEs from the sediment clearly influence the distribution of the dissolved REE concentrations at certain locations. Nevertheless, the Nd isotope signatures clearly trace water masses including AAIW (Antarctic Intermediate Water) (average ?Nd = -8.2 ± 0.3), LCDW (Lower Circumpolar Deep Water) (average ?Nd = -8.3 ± 0.3), NPDW (North Pacific Deep Water) (average ?Nd = -5.9 ± 0.3), and the remnants of NADW (North Atlantic Deep Water) (average ?Nd = -9.7 ± 0.3). Filtered water samples taken from the sediment-water interface under the deep western boundary current off New Zealand suggest that boundary exchange processes are limited at this location and highlight the spatial and temporal variability of this process. These data will serve as a basis for the paleoceanographic application of Nd isotopes in the South Pacific.

  19. Neodymium isotopic study of rare earth element sources and mobility in hydrothermal Fe oxide (Fe-P-REE) systems

    SciTech Connect

    Gleason, J.D.; Marikos, M.A.; Barton, M.D.; Johnson, D.A.

    2000-03-01

    Rare earth element (REE)-enriched, igneous-related hydrothermal Fe-oxide hosted (Fe-P-REE) systems from four areas in North America have been analyzed for their neodymium iosotopic composition to constrain REE sources and mobility in these systems. The Nd isotopic results evidence a common pattern of REE concentration from igneous sources despite large differences in age (Proterozoic to Tertiary), tectonic setting (subduction vs. intraplate), and magmatic style (mafic vs. felsic). In the Middle Proterozoic St. Francois Mountains terrane of southeastern Missouri, {epsilon}{sub Nd} for Fe-P-REE (apatite, monazite, xenotime) deposits ranges from +3.5 to +5.1, similar to associated felsic to intermediate igneous rocks of the same age ({epsilon}{sub Nd} = +2.6 to +6.2). At the mid-Jurassic Humboldt mafic complex in western Nevada, {epsilon}{sub Nd} for Fe-P-REE (apatite) mineralization varies between +1.1 and +2.4, similar to associated mafic igneous rocks ({minus}1.0 to +3.5). In the nearby Cortez Mountains in central Nevada, mid-Jurassic felsic volcanic and plutonic rocks ({epsilon}{sub Nd} = {minus}2.0 to {minus}4.4) are associated with Fe-P-REE (apatite-monazite) mineralization having similar {epsilon}{sub Nd}({minus}1.7 to {minus}2.4). At Cerro de Mercado, Durango, Mexico, all assemblages analyzed in this Tertiary rhyolite-hosted Fe oxide deposit have identical isotopic compositions with {epsilon}{sub Nd} = {minus}2.5. These data are consistent with coeval igneous host rocks being the primary source of REE in all four regions, and are inconsistent with a significant contribution of REE from other sources. Interpretations of the origin of these hydrothermal systems and their concomitant REE mobility must account for nonspecialized igneous sources and varied tectonic settings.

  20. Biotic ligand model does not predict the bioavailability of rare Earth elements in the presence of organic ligands.

    PubMed

    Zhao, Chun-Mei; Wilkinson, Kevin J

    2015-02-17

    Due to their distinct physicochemical properties, rare earth elements (REEs) are critical to high-tech and clean-energy industries; however, their bioavailability is still largely unexplored. In this paper, the bioavailability of several REEs has been carefully examined for the freshwater alga, Chlamydomonas reinhardtii. In the presence of organic ligands (L), the biouptake of REEs was much higher than that predicted by the biotic ligand model (BLM). Enhancement of the biouptake flux was observed for six ligands (metal = thulium) and six REEs (ligand = citric acid), indicating that this could be a common feature for these metals. In order to explore the mechanism for the enhanced uptake, Tm internalization was carefully evaluated. The Tm internalization flux (Jint) followed first-order (Michaelis-Menten) kinetics with a calculated maximum internalization flux (Jmax) of (1.1 ± 0.08) × 10(-14) mol · cm(-2) · s(-1) and an affinity constant for the reaction of the metal with the transport sites (KTm-R) of 10(7.1) M(-1). In the presence of citric acid, malic acid, or NTA, the Jint for Tm was more than 1 order of magnitude higher than that predicted by the BLM when algae were exposed to a constant 10(-9) M Tm(3+). The bioavailability of the metal complexes could not be explained by a piggyback internalization (through an anion channel) or the contribution of labile complexes. The enhanced biouptake was attributed to the formation of a ternary Tm complex {L-Tm-R} at the metal transport site. In the natural environment where organic ligands are ubiquitous, classic models are unlikely to predict the bioavailability of REEs to aquatic organisms. PMID:25611881

  1. Microwave-induced combustion of crude oil for further rare earth elements determination by USN-ICP-MS.

    PubMed

    Pereira, J S F; Pereira, L S F; Mello, P A; Guimarães, R C L; Guarnieri, R A; Fonseca, T C O; Flores, E M M

    2014-09-24

    A procedure for light and heavy crude oils digestion by microwave-induced combustion (MIC) is proposed for the first time for further rare earth elements (REE) determination by inductively coupled plasma mass spectrometry (ICP-MS) equipped with an ultrasonic nebulizer (USN). Samples of crude oil (API density of 10.8-23.5, up to 250 mg) were inserted in polycarbonate capsules and combusted using 20 bar of oxygen and 50 ?L of 6 mol L(-1) ammonium nitrate as igniter. Nitric acid solutions (1-14.4 mol L(-1)) were evaluated for analyte absorption and a reflux step was applied after combustion (5 min of microwave irradiation at 1400 W) in order to achieve better analyte recoveries. Accuracy was evaluated using a spiked sample and also by comparison of results obtained by microwave-assisted digestion combined to ultraviolet radiation (MW-UV) and by neutron activation analysis (NAA). Using 3 mol L(-1) HNO3, quantitative recoveries (better than 97%) were obtained for all analytes. Blank values were always negligible. Agreement was higher than 96% for La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y by comparison of results with those obtained by MW-UV and by NAA (only for La, Ce, Nd, Sm, and Yb). Residual carbon content in digests using MIC was always below 1%. As an advantage over conventional procedures for crude oil digestion, using MIC, it was possible to use diluted acid as absorbing solution, obtaining better limits of detection and avoiding interferences in REE determination by USN-ICP-MS. PMID:25172810

  2. Geophysical expression of a buried niobium and rare earth element deposit: the Elk Creek carbonatite, Nebraska, USA

    USGS Publications Warehouse

    Drenth, Benjamin J.

    2014-01-01

    The lower Paleozoic Elk Creek carbonatite is a 6–8-km-diameter intrusive complex buried under 200 m of sedimentary rocks in southeastern Nebraska. It hosts the largest known niobium deposit in the U.S. and a rare earth element (REE) deposit. The carbonatite is composed of several lithologies, the relations of which are poorly understood. Niobium mineralization is most enriched within a magnetite beforsite (MB) unit, and REE oxides are most concentrated in a barite beforsite unit. The carbonatite intrudes Proterozoic country rocks. Efforts to explore the carbonatite have used geophysical data and drilling. A high-resolution airborne gravity gradient and magnetic survey was flown over the carbonatite in 2012. The carbonatite is associated with a roughly annular vertical gravity gradient high and a subdued central low and a central magnetic high surrounded by magnetic field values lower than those over the country rocks. Geophysical, borehole, and physical property data are combined for an interpretation of these signatures. The carbonatite is denser than the country rocks, explaining the gravity gradient high. Most carbonatite lithologies have weaker magnetic susceptibilities than those of the country rocks, explaining why the carbonatite does not produce a magnetic high at its margin. The primary source of the central magnetic high is interpreted to be mafic rocks that are strongly magnetized and are present in large volumes. MB is very dense (mean density 3200??kg/m3) and strongly magnetized (median 0.073 magnetic susceptibility), producing a gravity gradient high and contributing to the aeromagnetic high. Barite beforsite has physical properties similar to most of the carbonatite volume, making it a poor geophysical target. Geophysical anomalies indicate the presence of dense and strongly magnetized rocks at depths below existing boreholes, either a large volume of MB or another unknown lithology.

  3. Am phases in the matrix of a U–Pu–Zr alloy with Np, Am, and rare-earth elements

    SciTech Connect

    Janney, Dawn E.; Kennedy, J. Rory; Madden, James W.; O’Holleran, Thomas P.

    2015-01-01

    Phases and microstructures in the matrix of an as-cast U-Pu-Zr alloy with 3 wt% Am, 2% Np, and 8% rare-earth elements were characterized by scanning and transmission electron microscopy. The matrix consists primarily of two phases, both of which contain Am: ?-(U, Np, Pu, Am) (~70 at% U, 5% Np, 14% Pu, 1% Am, and 10% Zr) and ?-(U, Np, Pu, Am)Zr2 (~25% U, 2% Np, 10-15% Pu, 1-2% Am, and 55-60 at% Zr). These phases are similar to those in U-Pu-Zr alloys, although the Zr content in ?-(U, Np, Pu, Am) is higher than that in ?-(U, Pu) and the Zr content in ?-(U, Np, Pu, Am)Zr2 is lower than that in ?-UZr2. Nanocrystalline actinide oxides with structures similar to UO2 occurred in some areas, but may have formed by reactions with the atmosphere during sample handling. Planar features consisting of a central zone of ?-(U, Np, Pu, Am) bracketed by zones of ?-(U, Np, Pu,