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Sample records for earth element geochemistry

  1. The Marine Geochemistry of the Rare Earth Elements

    DTIC Science & Technology

    1983-09-01

    C3): 2045-2056. BACON, M.P., P.G. BREWER, D.W. SPENCER, T.W. MURRAY & T. GODDARD (1980). Lead - 210 , polonium - 210 , manganese and iron in the Cariaco...191 La and Pr 197 Ce: its oxidation and reduction 197 Eu 207 4.5. Conclusions 210 CHAPTER 5. Behaviour of the Rare Earth Elements in anoxic waters of...0.142 140Ce(n, )14ICe 0.58 0.48 2.89 0.0053 41Pr(n,e.)142Pr 11.5 14.1 57.4 0.17 l46Nd(n,a-)l47Nd 1.4 3.2 6.98 0.0039 152Sni(n,a)153Sm 210 2530 1047

  2. Rare earth element geochemistry of outcrop and core samples from the Marcellus Shale

    DOE PAGES

    Noack, Clinton W.; Jain, Jinesh C.; Stegmeier, John; ...

    2015-06-26

    In this paper, we studied the geochemistry of the rare earth elements (REE) in eleven outcrop samples and six, depth-interval samples of a core from the Marcellus Shale. The REE are classically applied analytes for investigating depositional environments and inferring geochemical processes, making them of interest as potential, naturally occurring indicators of fluid sources as well as indicators of geochemical processes in solid waste disposal. However, little is known of the REE occurrence in the Marcellus Shale or its produced waters, and this study represents one of the first, thorough characterizations of the REE in the Marcellus Shale. In thesemore » samples, the abundance of REE and the fractionation of REE profiles were correlated with different mineral components of the shale. Namely, samples with a larger clay component were inferred to have higher absolute concentrations of REE but have less distinctive patterns. Conversely, samples with larger carbonate fractions exhibited a greater degree of fractionation, albeit with lower total abundance. Further study is necessary to determine release mechanisms, as well as REE fate-and-transport, however these results have implications for future brine and solid waste management applications.« less

  3. Rare earth element geochemistry of outcrop and core samples from the Marcellus Shale

    SciTech Connect

    Noack, Clinton W.; Jain, Jinesh C.; Stegmeier, John; Hakala, J. Alexandra; Karamalidis, Athanasios K.

    2015-06-26

    In this paper, we studied the geochemistry of the rare earth elements (REE) in eleven outcrop samples and six, depth-interval samples of a core from the Marcellus Shale. The REE are classically applied analytes for investigating depositional environments and inferring geochemical processes, making them of interest as potential, naturally occurring indicators of fluid sources as well as indicators of geochemical processes in solid waste disposal. However, little is known of the REE occurrence in the Marcellus Shale or its produced waters, and this study represents one of the first, thorough characterizations of the REE in the Marcellus Shale. In these samples, the abundance of REE and the fractionation of REE profiles were correlated with different mineral components of the shale. Namely, samples with a larger clay component were inferred to have higher absolute concentrations of REE but have less distinctive patterns. Conversely, samples with larger carbonate fractions exhibited a greater degree of fractionation, albeit with lower total abundance. Further study is necessary to determine release mechanisms, as well as REE fate-and-transport, however these results have implications for future brine and solid waste management applications.

  4. Rare earth element geochemistry of outcrop and core samples from the Marcellus Shale.

    PubMed

    Noack, Clinton W; Jain, Jinesh C; Stegmeier, John; Hakala, J Alexandra; Karamalidis, Athanasios K

    2015-01-01

    In this work, the geochemistry of the rare earth elements (REE) was studied in eleven outcrop samples and six, depth-interval samples of a core from the Marcellus Shale. The REE are classically applied analytes for investigating depositional environments and inferring geochemical processes, making them of interest as potential, naturally occurring indicators of fluid sources as well as indicators of geochemical processes in solid waste disposal. However, little is known of the REE occurrence in the Marcellus Shale or its produced waters, and this study represents one of the first, thorough characterizations of the REE in the Marcellus Shale. In these samples, the abundance of REE and the fractionation of REE profiles were correlated with different mineral components of the shale. Namely, samples with a larger clay component were inferred to have higher absolute concentrations of REE but have less distinctive patterns. Conversely, samples with larger carbonate fractions exhibited a greater degree of fractionation, albeit with lower total abundance. Further study is necessary to determine release mechanisms, as well as REE fate-and-transport, however these results have implications for future brine and solid waste management applications.

  5. 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 ΣREE 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

  6. Rethinking early Earth phosphorus geochemistry

    PubMed Central

    Pasek, Matthew A.

    2008-01-01

    Phosphorus is a key biologic element, and a prebiotic pathway leading to its incorporation into biomolecules has been difficult to ascertain. Most potentially prebiotic phosphorylation reactions have relied on orthophosphate as the source of phosphorus. It is suggested here that the geochemistry of phosphorus on the early Earth was instead controlled by reduced oxidation state phosphorus compounds such as phosphite (HPO32−), which are more soluble and reactive than orthophosphates. This reduced oxidation state phosphorus originated from extraterrestrial material that fell during the heavy bombardment period or was produced during impacts, and persisted in the mildly reducing atmosphere. This alternate view of early Earth phosphorus geochemistry provides an unexplored route to the formation of pertinent prebiotic phosphorus compounds, suggests a facile reaction pathway to condensed phosphates, and is consistent with the biochemical usage of reduced oxidation state phosphorus compounds in life today. Possible studies are suggested that may detect reduced oxidation state phosphorus compounds in ancient Archean rocks. PMID:18195373

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Rare earth element geochemistry of oceanic ferromanganese nodules and associated sediments

    NASA Astrophysics Data System (ADS)

    Elderfield, H.; Hawkesworth, C. J.; Greaves, M. J.; Calvert, S. E.

    1981-04-01

    Analyses have been made of REE contents of a well-characterized suite of deep-sea (> 4000 m.) principally todorokite-bearing ferromanganese nodules and associated sediments from the Pacific Ocean. REE in nodules and their sediments are closely related: nodules with the largest positive Ce anomalies are found on sediments with the smallest negative Ce anomalies; in contrast, nodules with the highest contents of other rare earths (3 + REE) are found on sediments with the lowest 3 + REE contents and vice versa. 143Nd /144Nd ratios in the nodules (˜0.51244) point to an original seawater source but an identical ratio for sediments in combination with the REE patterns suggests that diagenetic reactions may transfer elements into the nodules. Analysis of biogenic phases shows that the direct contribution of plankton and carbonate and siliceous skeletal materials to REE contents of nodules and sediments is negligible. Inter-element relationships and leaching tests suggest that REE contents are controlled by a P-rich phase with a REE pattern similar to that for biogenous apatite and an Fe-rich phase with a pattern the mirror image of that for sea water. It is proposed that 3 + REE concentrations are controlled by the surface chemistry of these phases during diagenetic reactions which vary with sediment accumulation rate. Processes which favour the enrichment of transition metals in equatorial Pacific nodules favour the depletion of 3 + REE in nodules and enrichment of 3 + REE in associated sediments. In contrast, Ce appears to be added both to nodules and sediments directly from seawater and is not involved in diagenetic reactions.

  15. 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.

  16. 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

  17. Geochemistry of some rare earth elements in groundwater, Vierlingsbeek, The Netherlands.

    PubMed

    Janssen, René P T; Verweij, Wilko

    2003-03-01

    Groundwater samples were taken from seven bore holes at depths ranging from 2 to 41m nearby drinking water pumping station Vierlingsbeek, The Netherlands and analysed for Y, La, Ce, Pr, Nd, Sm and Eu. Shale-normalized patterns were generally flat and showed that the observed rare earth elements (REE) were probably of natural origin. In the shallow groundwaters the REEs were light REE (LREE) enriched, probably caused by binding of LREEs to colloids. To improve understanding of the behaviour of the REE, two approaches were used: calculations of the speciation and a statistical approach. For the speciation calculations, complexation and precipitation reactions including inorganic and dissolved organic carbon (DOC) compounds, were taken into account. The REE speciation showed REE(3+), REE(SO(4))(+), REE(CO(3))(+) and REE(DOC) being the major species. Dissolution of pure REE precipitates and REE-enriched solid phases did not account for the observed REEs in groundwater. Regulation of REE concentrations by adsorption-desorption processes to Fe(III)(OH)(3) and Al(OH)(3) minerals, which were calculated to be present in nearly all groundwaters, is a probable explanation. The statistical approach (multiple linear regression) showed that pH is by far the most significant groundwater characteristic which contributes to the variation in REE concentrations. Also DOC, SO(4), Fe and Al contributed significantly, although to a much lesser extent, to the variation in REE concentrations. This is in line with the calculated REE-species in solution and REE-adsorption to iron and aluminium (hydr)oxides. Regression equations including only pH, were derived to predict REE concentrations in groundwater. External validation showed that these regression equations were reasonably successful to predict REE concentrations of groundwater of another drinking water pumping station in quite different region of The Netherlands.

  18. The estuarine geochemistry of rare earth elements and indium in the Chao Phraya River, Thailand

    NASA Astrophysics Data System (ADS)

    Nozaki, Yoshiyuki; Lerche, Dorte; Alibo, Dia Sotto; Snidvongs, Anond

    2000-12-01

    A new filtration method using a 0.04 μm hollow fiber filter was applied to the river, estuarine, and coastal waters in the Chao Phraya estuary for geochemical investigation. The filtered waters were analyzed for all the lanthanides, Y and In by using inductively coupled plasma mass spectrometry (ICPMS). The dissolved concentrations of rare earth elements (REEs) are significantly lower than those reported previously for other rivers, presumably because of effective removal of river colloids by the ultra-filtration. The variation of dissolved REEs in the estuary is dependent on the season. The light REEs vary considerably in the low salinity ( S < 3) zone presumably due to adsorption-desorption interaction with suspended particles. In January when the river discharge is low, the REEs show maxima in the mid salinity ( S = 5-12) zone suggesting that dissolved REEs are supplied to the waters by either desorption from suspended loads or remineralization of underlying sediments. The rapid removal of the REEs is also taking place in the turbid-clear water transition zone ( S = 12-15), presumably due to biological uptake associated with blooming of Noctilca occurred at the time of January sampling. In the medium to high discharge season (July and November), the dissolved REE(III)s at S > 3 show almost conservative trends being consistent with some of the previous works. Europium is strongly enriched in the river and estuarine waters compared to the South China Sea waters. Thus, the REE source of the Chao Phraya River must be fractionated and modified in entering to the South China Sea. Dissolved In and Ce in the high salinity ( S = 20-25) zone of the estuary are lower than those of the offshore waters, and therefore, the dissolved flux of the Chao Phraya River cannot account for the higher concentrations of dissolved In and Ce in the surface waters of the South China Sea. The negative Ce anomaly is progressively developed with increasing salinity, being consistent with

  19. Strontium isotopes and rare-earth element geochemistry of hydrothermal carbonate deposits from Lake Tanganyika, East Africa

    SciTech Connect

    Barrat, J.A.; Boulegue, J.; Tiercelin, J.J.; Lesourd, M.

    2000-01-01

    At Cape Banza (North Tanganyika Lake), fluids and aragonite chimneys have been collected many times since the discovery of this sublacustrine field in 1987. This sampling has been investigated here for the Sr isotopic compositions and the rare-earth element features of the carbonates and a few fluid samples. The {sup 87}Sr/{sup 86}Sr ratios of the chimneys indicate that they have precipitated from a mixture of lake water (more than 95%) and hydrothermal fluids. No zoning in the chimneys was detected with the Sr data. For the rare-earth elements, the situation is more complex. The external walls of the chimneys are rare-earth-element-poor (La {approx} 500 ppb, Yb {approx} 200 ppb, La/Yb = 2 to 3.4). Their shale normalized rare-earth element patterns suggest that they are in equilibrium with the inferred carbonate-depositing fluids. The rare-earth element concentrations of the internal walls of the chimneys are significantly light rare earth elements (LREE)-enriched with La contents sometimes up to 5 ppm. The authors suggest that they contain more vent-fluid rare-earth elements than the external wall samples, possibly adsorbed on the surface of growing crystals or simply hosted by impurities. It was not possible to constrain the nature of these phases, but the variations of the compositions of the internal wall materials of the active chimneys with time, as well as data obtained on an inactive chimney indicate that this rare-earth element excess is mobile. Partition coefficients were calculated between the external wall aragonite and carbonate-depositing fluid. The results are strikingly similar to the values obtained by Sholkovitz and Shen (1995) on coral aragonite, and suggest that there is no significant biologic effect on the incorporation of rare-earth elements into coral aragonite and that the various carbonate complexes involved Me(CO{sub 3}{sup +}) complexes are the main LREE carriers in seawater instead of Me(CO{sub 3}){sub 2}{sup {minus}} in Banza fluids

  20. 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.

  1. Rare earth element geochemistry of shallow carbonate outcropping strata in Saudi Arabia: Application for depositional environments prediction

    NASA Astrophysics Data System (ADS)

    Eltom, Hassan A.; Abdullatif, Osman M.; Makkawi, Mohammed H.; Eltoum, Isam-Eldin A.

    2017-03-01

    The interpretation of depositional environments provides important information to understand facies distribution and geometry. The classical approach to interpret depositional environments principally relies on the analysis of lithofacies, biofacies and stratigraphic data, among others. An alternative method, based on geochemical data (chemical element data), is advantageous because it can simply, reproducibly and efficiently interpret and refine the interpretation of the depositional environment of carbonate strata. Here we geochemically analyze and statistically model carbonate samples (n = 156) from seven sections of the Arab-D reservoir outcrop analog of central Saudi Arabia, to determine whether the elemental signatures (major, trace and rare earth elements [REEs]) can be effectively used to predict depositional environments. We find that lithofacies associations of the studied outcrop (peritidal to open marine depositional environments) possess altered REE signatures, and that this trend increases stratigraphically from bottom-to-top, which corresponds to an upward shallowing of depositional environments. The relationship between REEs and major, minor and trace elements indicates that contamination by detrital materials is the principal source of REEs, whereas redox condition, marine and diagenetic processes have minimal impact on the relative distribution of REEs in the lithofacies. In a statistical model (factor analysis and logistic regression), REEs, major and trace elements cluster together and serve as markers to differentiate between peritidal and open marine facies and to differentiate between intertidal and subtidal lithofacies within the peritidal facies. The results indicate that statistical modelling of the elemental composition of carbonate strata can be used as a quantitative method to predict depositional environments and regional paleogeography. The significance of this study lies in offering new assessments of the relationships between

  2. 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 μg/g and 64-152 μg/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

  3. Geochemistry of rare earth elements in basalts from the Walvis Ridge: implications for its origin and evolution

    NASA Astrophysics Data System (ADS)

    Humphris, Susan E.; Thompson, Geoffrey

    1983-12-01

    Selected basalts from a suite of dredged and drilled samples (IPOD sites 525, 527, 528 and 530) from the Walvis Ridge have been analysed to determine their rare earth element (REE) contents in order to investigate the origin and evolution of this major structural feature in the South Atlantic Ocean. All of the samples show a high degree of light rare earth element (LREE) enrichment, quite unlike the flat or depleted patterns normally observed for normal mid-ocean ridge basalts (MORBs). Basalts from Sites 527, 528 and 530 show REE patterns characterised by an arcuate shape and relatively low (Ce/Yb) N ratios (1.46-5.22), and the ratios show a positive linear relationship to Nb content. A different trend is exhibited by the dredged basalts and the basalts from Site 525, and their REE patterns have a fairly constant slope, and higher (Ce/Yb) N ratios (4.31-8.50). These differences are further reflected in the ratios of incompatible trace elements, which also indicate considerable variations within the groups. Mixing hyperbolae for these ratios suggest that simple magma mixing between a "hot spot" type of magma, similar to present-day volcanics of Tristan da Cunha, and a depleted source, possibly similar to that for magmas being erupted at the Mid-Atlantic Ridge, was an important process in the origin of parts of the Walvis Ridge, as exemplified by Sites 527, 528 and 530. Site 525 and dredged basalts cannot be explained by this mixing process, and their incompatible element ratios suggest either a mantle source of a different composition or some complexity to the mixing process. In addition, the occurrence of different types of basalt at the same location suggests there is vertical zonation within the volcanic pile, with the later erupted basalts becoming more alkaline and more enriched in incompatible elements. The model proposed for the origin and evolution of the Walvis Ridge involves an initial stage of eruption in which the magma was essentially a mixture of

  4. 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

  5. Geochemistry of rare earth elements in minesoils from São Domingos mining district (Iberian Pyrite Belt)

    NASA Astrophysics Data System (ADS)

    Delgado, Joaquin; Perez-Lopez, Rafael; Nieto, Jose Miguel; Ayora, Carles

    2010-05-01

    The São Domingos mine is one of the most emblematic mining districts in the lower part of the Guadiana River Basin (SW of Iberian Peninsula). It is located in Portugal (about 5 km from the Spanish border), in the northern sector of the Iberian Pyrite Belt (IPB), one of the largest metallogenetic provinces of massive sulphides in the world. Although mining activity has ceased at present, the large-scale exploitation of this deposit between the second half of the XIX century and the first half of the XX century, has favoured the production of enormous waste dumps, where oxidation of pyrite and associated sulphides is resulting in the production of acid mine drainage (AMD). Mining wastes, minesoils, and acid mine drainage have been analyzed for their major ions and rare earth elements (REE) with the aim of understanding the REE mobility during sulphide weathering so that lanthanoid series can be used both as a proxy for the extent of water-rock interaction and as a tool for identifying impacts of AMD on natural ecosystems. Chemical speciation of REE in extracts from minesoils indicates that REE sulphate complexes (mainly LnSO4+) are the primary aqueous form (60-90%), and free ionic species (Ln3+, 10-40%) are the next most abundant form of soil water-soluble fraction and controls the REE speciation model. The REE from this fraction have NASC-normalized patterns with middle-REE (MREE) enriched signature compared to the light-REE (LREE) and heavy-REE (HREE), showing convex MREE-signatures and convexity index values of +1.29 +/- 1.13. These results are consistent with the typical REE fractionation patterns reported for AMD. Poorly crystalline iron oxyhydroxysulphates act as a source of labile MREE by dissolution and/or desorption processes and could explain the MREE-enriched signatures in solution.

  6. Trace and Rare Earth Element Geochemistry of Black Shales in Triassic Kasimlar Formation, Anamas-Akseki Platform, Western Taurids, Turkey

    NASA Astrophysics Data System (ADS)

    Kuşcu, Mustafa; Özsoy, Rifat; Özçelik, Orhan; Altunsoy, Mehmet

    2016-10-01

    The Triassic black shale sequence of Kasimlar Formation in the Anamas - Akseki Platform, Western Taurids, Turkey do not show any trace element enrichment. But trace element values of Black shales from the Kasimlar Formation are broadly comparable with those of the average upper continental crust. While there are slightly enrichments in As, Bi, Zn, Nb, Cu, Pb, Cs and Sb. The other elements are slightly depleted in black shales according to those of upper continental crust (UC). Organic carbon content of the black shales is between 05 and 0.71% but reach 3.78% (averaging as 0.52%). The black shales do not show metal/TOC correlation. Compared to the black shales of Kasimlar Formation and upper continental crust; The black shales show a significant increase in HREE and LREE. Our data show slightly negative Ce anomalies (Ce/Ce* as low as 0.94) and positive Eu anomalies (Eu/Eu* as high as 3.33). Ce/Ce* and Eu/Eu* values recorded in the depositional environment indicate low oxygenated and anaerobic (reducing) conditions.

  7. The Medical Geochemistry of Dusts, Soils, and Other Earth Materials

    NASA Astrophysics Data System (ADS)

    Plumlee, G. S.; Ziegler, T. L.

    2003-12-01

    "Town clenched in suffocating grip of asbestos"USA Today, article on Libby,Montana, February, 2000"Researchers find volcanoes are bad for your health… long after they finish erupting"University of WarwickPress Release, 1999"Toxic soils plague city - arsenic, lead in 5 neighborhoods could imperil 17,000 residents"Denver Post, 2002"Ill winds - dust storms ferry toxic agents between countries and even continents"Science News, 2002A quick scan of newspapers, television, science magazines, or the internet on any given day has a fairly high likelihood of encountering a story (usually accompanied by a creative headline such as those above) regarding human health concerns linked to dusts, soils, or other earth materials. Many such concerns have been recognized and studied for decades, but new concerns arise regularly.Earth scientists have played significant roles in helping the medical community understand some important links between earth materials and human health, such as the role of asbestos mineralogy in disease (Skinner et al., 1988; Ross, 1999; Holland and Smith, 2001), and the role of dusts generated by the 1994 Northridge, California, earthquake in an outbreak of Valley Fever ( Jibson et al., 1998; Schneider et al., 1997).Earth science activities tied to health issues are growing (Skinner and Berger, 2003), and are commonly classified under the emerging discipline of medical geology (Finkelman et al., 2001; Selinus and Frank, 2000; Selinus, in press).Medical geochemistry (also referred to as environmental geochemistry and health: Smith and Huyck (1999), Appleton et al. (1996)) can be considered as a diverse subdiscipline of medical geology that deals with human and animal health in the context of the Earth's geochemical cycle ( Figure 1). Many medical geochemistry studies have focused on how chemical elements in rocks, soils, and sediments are transmitted via water or vegetation into the food chain, and how regional geochemical variations can result in disease

  8. Insights into Igneous Geochemistry from Trace Element Partitioning

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Hanson, B. Z.

    2001-01-01

    Partitioning of trivalent elements into olivine are used to explore basic issues relevant to igneous geochemistry, such as Henry's law. Additional information is contained in the original extended abstract.

  9. Rare earth element geochemistry of acid-sulphate and acid-sulphate-chloride geothermal systems from Yellowstone National Park, Wyoming, USA

    SciTech Connect

    Lewis, A.J.; Palmer, M.R.; Kemp, A.J.; Sturchio, N.C.

    1997-02-01

    Rare earth element (REE) concentrations have been determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in acid-sulphate and acid-sulphate-chloride waters and the associated sinters and volcanic rocks from the Yellowstone National Park (YNP), Wyoming, USA, geothermal system. REE concentrations in the volcanic rocks range from 222 to 347 ppm: their chondrite-normalised REE patterns are typical of upper continental crust, with LREE > HREE and negative Eu anomalies. Total REE concentrations in the fluids range from 3 to 1133 nmol kg{sup -1} ({ge}162 ppm), and {Sigma}REE concentrations in sinter are {ge}181 ppm. REE abundances and patterns in drill core material from YNP indicate some REE mobility. Relative to the host rocks the REE patterns of the fluids are variably depleted in HREEs and LREEs, and usually have a pronounced positive Eu anomaly. This decoupling of Eu from the REE suite suggests that (1) Eu has been preferentially removed either from the host rock glass or from the host rock minerals, or (2) the waters are from a high temperature or reducing environment where Eu{sup 2+} is more soluble than the trivalent REEs. Since the latter is inconsistent with production of acid-sulphate springs in a low temperature, oxidising near-surface environment, we suggest that the positive Eu anomalies in the fluids result from preferential dissolution of a Eu-rich phase in the host rock. Spatial and temporal variations in major element chemistry and pH of the springs sampled from Norris Geyser Basin and Crater Hills accompany variations in REE concentrations and patterns of individual geothermal springs. These are possibly related to changes in subsurface plumbing, which results in variations in mixing and dilution of the geothermal fluids and may have lead to changes in the extent and nature of REE complexing. 37 refs., 7 figs., 4 tabs.

  10. The rare earth element geochemistry of acid-sulphate and acid-sulphate-chloride geothermal systems from Yellowstone National Park, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Lewis, Anita J.; Palmer, Martin R.; Sturchio, Neil C.; Kemp, Anthony J.

    1997-02-01

    Rare earth element (REE) concentrations have been determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in acid-sulphate and acid-sulphate-chloride waters and the associated sinters and volcanic rocks from the Yellowstone National Park (YNP), Wyoming, USA, geothermal system. REE concentrations in the volcanic rocks range from 222 to 347 ppm; their chondite-normalised REE patterns are typical of upper continental crust, with LREE > HREE and negative Eu anomalies. Total REE concentrations in the fluids range from 3 to 1133 nmol kg -1 (≥ 162 ppm), and ΣREE concentrations in sinter are ≥ 181 ppm. REE abundances and patterns in drill core material from YNP indicate some REE mobility. Normalisation of REE concentrations in altered Lava Creek Tuff (LCT) from Y-12 drill core to REE concentrations in fresh LCT indicate that the REE overall have been depleted with the exception of Eu, which has been decoupled from the REE series and concentrated in the altered rocks. Relative to the host rocks the REE patterns of the fluids are variably depleted in HREEs and LREEs, and usually have a pronounced positive Eu anomaly. This decoupling of Eu from the REE suite suggests that (1) Eu has been preferentially removed either from the host rock glass or from the host rock minerals, or (2) the waters are from a high temperature or reducing environment where Eu 2+ is more soluble than the trivalent REEs. Since the latter is inconsistent with production of acid-sulphate springs in a low temperature, oxidising near-surface environment, we suggest that the positive Eu anomalies in the fluids result from preferential dissolution of a Eu-rich phase in the host rock. Spatial and temporal variations in major element chemistry and pH of the springs sampled from Norris Geyser Basin and Crater Hills accompany variations in REE concentrations and patterns of individual geothermal springs. These are possibly related to changes in subsurface plumbing, which results in variations in

  11. Geochemistry of rare earth elements in the Baba Ali magnetite skarn deposit, western Iran - a key to determine conditions of mineralisation

    NASA Astrophysics Data System (ADS)

    Zamanian, Hassan; Radmard, Kaikosrov

    2016-03-01

    The Baba Ali skarn deposit, situated 39 km to the northwest of Hamadan (Iran), is the result of a syenitic pluton that intruded and metamorphosed the diorite host rock. Rare earth element (REE) values in the quartz syenite and diorite range between 35.4 and 560 ppm. Although the distribution pattern of REEs is more and less flat and smooth, light REEs (LREEs) in general show higher concentrations than heavy REEs (HREEs) in different lithounits. The skarn zone reveals the highest REE-enriched pattern, while the ore zone shows the maximum depletion pattern. A comparison of the concentration variations of LREEs (La-Nd), middle REEs (MREEs; Sm-Ho) and HREEs (Er-Lu) of the ore zone samples to the other zones elucidates two important points for the distribution of REEs: 1) the distribution patterns of LREEs and MREEs show a distinct depletion in the ore zone while representing a great enrichment in the skarn facies neighbouring the ore body border and decreasing towards the altered diorite host rock; 2) HREEs show the same pattern, but in the exoskarn do not reveal any distinct increase as observed for LREEs and MREEs. The ratio of La/Y in the Baba Ali skarn ranges from 0.37 to 2.89. The ore zone has the highest La/Y ratio. In this regard the skarn zones exhibit two distinctive portions: 1) one that has La/Y >1 beingadjacent to the ore body and; 2) another one with La/Y < 1 neighbouring altered diorite. Accordingly, the Baba Ali profile, from the quartz syenite to the middle part of the exoskarn, demonstrates chiefly alkaline conditions of formation, with a gradual change to acidic towards the altered diorite host rocks. Utilising three parameters, Ce/Ce*, Eu/Eu* and (Pr/Yb)n, in different minerals implies that the hydrothermal fluids responsible for epidote and garnet were mostly of magmatic origin and for magnetite, actinolite and phlogopite these were of magmatic origin with low REE concentration or meteoric water involved.

  12. Rare earth element and Nd isotope geochemistry of an ombrotrophic peat bog at Karukinka (Chile, 53.9° S): a palaeo-record of Holocene dust deposition in Tierra del Fuego.

    NASA Astrophysics Data System (ADS)

    Vanneste, Heleen; De Vleeschouwer, François; Vanderstraeten, Aubry; Mattielli, Nadine; Triquet, Delphine; Piotrowska, Natalia; Le Roux, Gael

    2013-04-01

    The value of ombrotrophic peat bogs as past atmospheric dust records, has been increasingly recognized over the past 10 years. Their high accumulation rates provide high resolution archives of natural atmospheric dust deposition since the Late Glacial, often missing in marine, lake and ice core records. Consequently, peat deposits can be used as a proxy for atmospheric circulation patterns and thus palaeoclimate. In the Southern Hemisphere, the climate is considered to be driven by the Southern Westerly Wind belt (SSW), as it significantly affects the Antarctic Circumpolar Current and hence atmospheric CO2 levels. Palaeo SSW belt migrations have been observed in palaeoclimate records but, reconstructions of SSW shifts and associated climatic changes are incoherent, in particular for the Holocene. As peatlands thrive in southwest Tierra del Fuego due to its high annual precipitation, a remote ombrotrophic peat bog at Karukinka (southwest on the Isla Grande de Tierra del Fuego) was sampled, to investigate the Holocene palaeoclimate in southern South America based on dust deposition records. A 4,5 m long Russian D-core was recovered and subsequently subsampled for elemental and isotope geochemistry in addition to density and radiocarbon dating measurements. Initial results show a number of layers enriched in scandium, indicating the presence of lithogenic material, i.e. dust. Rare earth element patterns indicate at least 2 different sources. The most significant dust peak occurs at the base of the core at ~7300 Cal years B.P and has a neodymium isotopic composition of 2.2, suggesting a volcanic origin.

  13. Scarcity of rare earth elements.

    PubMed

    de Boer, M A; Lammertsma, K

    2013-11-01

    Rare earth elements (REEs) are important for green and a large variety of high-tech technologies and are, therefore, in high demand. As a result, supply with REEs is likely to be disrupted (the degree of depends on the REE) in the near future. The 17 REEs are divided into heavy and light REEs. Other critical elements besides REEs, identified by the European Commission, are also becoming less easily available. Although there is no deficiency in the earth's crust of rare earth oxides, the economic accessibility is limited. The increased demand for REEs, the decreasing export from China, and geopolitical concerns on availability contributed to the (re)opening of mines in Australia and the USA and other mines are slow to follow. As a result, short supply of particularly terbium, dysprosium, praseodymium, and neodymium is expected to be problematic for at least the short term, also because they cannot be substituted. Recycling REEs from electronic waste would be a solution, but so far there are hardly any established REE recycling methods. Decreasing the dependency on REEs, for example, by identifying possible replacements or increasing their efficient use, represents another possibility.

  14. Geochemistry

    ERIC Educational Resources Information Center

    Ailin-Pyzik, Iris B.; Sommer, Sheldon E.

    1977-01-01

    Enumerates some of the research findings in geochemistry during the last year, including X-ray analysis of the Mars surface, trace analysis of fresh and esterarine waters, and analysis of marine sedements. (MLH)

  15. 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.

  16. EarthChem: International Collaboration for Solid Earth Geochemistry in Geoinformatics

    NASA Astrophysics Data System (ADS)

    Walker, J. D.; Lehnert, K. A.; Hofmann, A. W.; Sarbas, B.; Carlson, R. W.

    2005-12-01

    The current on-line information systems for igneous rock geochemistry - PetDB, GEOROC, and NAVDAT - convincingly demonstrate the value of rigorous scientific data management of geochemical data for research and education. The next generation of hypothesis formulation and testing can be vastly facilitated by enhancing these electronic resources through integration of available datasets, expansion of data coverage in location, time, and tectonic setting, timely updates with new data, and through intuitive and efficient access and data analysis tools for the broader geosciences community. PetDB, GEOROC, and NAVDAT have therefore formed the EarthChem consortium (www.earthchem.org) as a international collaborative effort to address these needs and serve the larger earth science community by facilitating the compilation, communication, serving, and visualization of geochemical data, and their integration with other geological, geochronological, geophysical, and geodetic information to maximize their scientific application. We report on the status of and future plans for EarthChem activities. EarthChem's development plan includes: (1) expanding the functionality of the web portal to become a `one-stop shop for geochemical data' with search capability across databases, standardized and integrated data output, generally applicable tools for data quality assessment, and data analysis/visualization including plotting methods and an information-rich map interface; and (2) expanding data holdings by generating new datasets as identified and prioritized through community outreach, and facilitating data contributions from the community by offering web-based data submission capability and technical assistance for design, implementation, and population of new databases and their integration with all EarthChem data holdings. Such federated databases and datasets will retain their identity within the EarthChem system. We also plan on working with publishers to ease the assimilation

  17. Recycling of Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Lorenz, Tom; Bertau, Martin

    2017-01-01

    Any development of an effective process for rare earth (RE) recycling has become more and more challenging, especially in recent years. Since 2011, when commodity prices of REs had met their all-time maximum, prices have dropped rapidly by more than 90 %. An economic process able to offset these fluctuations has to take unconventional methods into account beside well-known strategies like acid/basic leaching or solvent extraction. The solid-state chlorination provides such an unconventional method for mobilizing RE elements from waste streams. Instead of hydrochloric acid this kind of chlorination decomposes NH4Cl thermally to release up to 400 °C hot HCl gas. After cooling the resulting solid metal chlorides may be easily dissolved in pH-adjusted water. Without producing strongly acidic wastes and with NH4Cl as cheap source for hydrogen chloride, solid-state chlorination provides various advantages in terms of costs and disposal. In the course of the SepSELSA project this method was examined, adjusted and optimized for RE recycling from fluorescent lamp scraps as well as Fe14Nd2B magnets. Thereby many surprising influences and trends required various analytic methods to examine the reasons and special mechanisms behind them.

  18. Alteration geochemistry of the volcanic-hosted Dedeninyurdu, Yergen and Fındıklıyar Cu-Fe mineralization, Northern part of Gökçedoǧan Village, Çorum-Kargi Region, Turkey: Implications for the rare earth elements geochemical characteristics

    NASA Astrophysics Data System (ADS)

    Ozturk, Sercan; Gumus, Lokman; Abdelnasser, Amr; Yalçin, Cihan; Kumral, Mustafa; Hanilçi, Nurullah

    2016-04-01

    This study deals with the rare earth element (REE) geochemical behavior the alteration zonesassociated with the volcanic-hosted Cu-Femineralization at the northern part of Gökçedoǧan village, Çorum-Kargi region (N Turkey) which are Dedeninyurdu, Yergen and Fındıklıyar mineralization. The study areacomprises Bekirli Formation, Saraycık Formation, Beşpınar Formation, and Ilgaz Formation. Saraycık Formation consists ofUpper Cretaceous KargıOphiolites, pelagic limestone, siltstone, chert and spilitic volcanic rocks. Fe-Cu mineralization occurred in the spiliticvolcanic rocks of Saraycık Formation representing the host rockand is related with the silicification and sericitizationalteration zones. Dedeninyurdu and Yergen mineralization zone directed nearly N75-80oEis following structural a line but Fındıklıyar mineralization zone has nearly NW direction. The ore mineralogy in these zonesinclude pyrite, chalcopyrite, covellite, hematite with malachite, goethite and a limonite as a result of oxidation. The geochemical characteristics of REE of the least altered spiliticbasalt show flat light and heavy REE with slight positive Eu- and Sr-anomalies according to their chondrite-, N-type MORB, and primitive mantle-normalized REE patterns. While the REE geochemical features of the altered rocks collected from the different alteration zones show that there are negative Eu and Sr anomalies as a result of leaching during the alteration processes.There are positive and negative correlations between K2O index with LREE and HREE, respectively. This is due to the additions of K and La during the alteration processes referring to the pervasive sericitization alteration is the responsible for the Cu-Fe mineralization at the study area. Keywords: Cu-Fe mineralization, Spilitic volcanic rocks, alteration, Rare earth elements (REE) geochemistry.

  19. 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.

  20. 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.

  1. 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.

  2. Mineral resource of the month: rare earth elements

    USGS Publications Warehouse

    ,

    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.

  3. Geochemistry: does U-Pb date Earth's core formation?

    PubMed

    Yin, Qing-zhu; Jacobsen, Stein B

    2006-11-02

    Constraining the timing of the formation of Earth's core, which defines the birth of our planet, is essential for understanding the early evolution of Earth-like planets. Wood and Halliday and Halliday discuss the apparent discrepancy between the U-Pb (60-80 Myr) and Hf-W clocks (30 Myr) in determining the timescale of Earth's accretion and core formation. We find that the information the authors present is at times contradictory (for example, compare Fig. 1 in ref. 1 with Fig. 1 in ref. 2) and confusing and could suggest that the U-Pb clock constrains core formation better than the Hf-W system. Here we point out the limitations of the U-Pb system and show that the U-Pb age cannot be used to argue for protracted accretion and/or core formation (>50 Myr) because this clock only records the processes that occurred during the last 1% of Earth's accretion and core formation in the Wood and Halliday mechanism.

  4. Volatile Element Geochemistry in the Lower Atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Schaefer, L.; Fegley, B., Jr.

    2004-01-01

    We computed equilibrium abundances of volatile element compounds as a function of altitude in Venus lower atmosphere. The elements included are generally found in volcanic gases and sublimates on Earth and may be emitted in volcanic gases on Venus or volatilized from its hot surface. We predict: 1) PbS, Bi2S3, or possibly a Pb-Bi sulfosalt are the radar bright heavy metal frost in the Venusian highlands; 2) It should be possible to determine Venus' age by Pb-Pb dating of PbS condensed in the Venusian highlands, which should be a representative sample of Venusian lead; 3) The gases HBr, PbCl2, PbBr2, As4O6, As4S4, Sb4O6, BiSe, InBr, InCl, Hg, TlCl, TlBr, SeS, Se2-7, HI, I, I2, ZnCl2, and S2O have abundances greater than 0.1 ppbv in our nominal model and may be spectroscopically observable; 4) Cu, Ag, Au, Zn, Cd, Ge, and Sn are approx. 100 % condensed at the 740 K (0 km) level on Venus.

  5. Building the EarthChem System for Advanced Data Management in Igneous Geochemistry

    NASA Astrophysics Data System (ADS)

    Lehnert, K.; Walker, J. D.; Carlson, R. W.; Hofmann, A. W.; Sarbas, B.

    2004-12-01

    Several mature databases of geochemical analyses for igneous rocks are now available over the Internet. The existence of these databases has revolutionized access to data for researchers and students allowing them to extract data sets customized to their specific problem from global data compilations with their desktop computer within a few minutes. Three of the database efforts - PetDB, GEOROC, and NAVDAT - have initiated a collaborative effort called EarthChem to create better and more advanced and integrated data management for igneous geochemistry. The EarthChem web site (http://www.earthchem.org/) serves as a portal to the three databases and information related to EarthChem activities. EarthChem participants agreed to establish a dialog to minimize duplication of effort and share useful tools and approaches. To initiate this dialog, a workshop was run by EarthChem in October, 2003 to discuss cyberinfrastructure needs in igneous geochemistry (workshop report available at the EarthChem site). EarthChem ran an information booth with database and visualization demonstrations at the Fall 2003 AGU meeting (and will have one in 2004) and participated in the May 2003 GERM meeting in Lyon, France where we provided the newly established Publishers' Round Table a list of minimum standards of data reporting to ease the assimilation of data into the databases. Aspects of these suggestions already have been incorporated into new data policies at Geochimica et Cosmochimica Acta and Chemical Geology (Goldstein et al. 2004), and are under study by the Geological Society of America. EarthChem presented its objectives and activities to the Solid Earth Sciences community at the Annual GSA Meeting 2003 (Lehnert et al, 2003). Future plans for EarthChem include expanding the types and amounts of data available from a single portal, giving researchers, faculty, students, and the general public the ability to search, visualize, and download geochemical and geochronological data for a

  6. Rare earth element scavenging in seawater

    NASA Astrophysics Data System (ADS)

    Byrne, Robert H.; Kim, Ki-Hyun

    1990-10-01

    Examinations of rare earth element (REE) adsorption in seawater, using a variety of surface-types, indicated that, for most surfaces, light rare earth elements (LREEs) are preferentially adsorbed compared to the heavy rare earths (HREEs). Exceptions to this behavior were observed only for silica phases (glass surfaces, acid-cleaned diatomaceous earth, and synthetic SiO 2). The affinity of the rare earths for surfaces can be strongly affected by thin organic coatings. Glass surfaces which acquired an organic coating through immersion in Tampa Bay exhibited adsorptive behavior typical of organic-rich, rather than glass, surfaces. Models of rare earth distributions between seawater and carboxylate-rich surfaces indicate that scavenging processes which involve such surfaces should exhibit a strong dependence on pH and carbonate complexation. Scavenging models involving carboxylate surfaces produce relative REE abundance patterns in good general agreement with observed shale-normalized REE abundances in seawater. Scavenging by carboxylate-rich surfaces should produce HREE enrichments in seawater relative to the LREEs and may produce enrichments of lanthanum relative to its immediate trivalent neighbors. Due to the origin of distribution coefficients as a difference between REE solution complexation (which increases strongly with atomic number) and surface complexation (which apparently also increases with atomic number) the relative solution abundance patterns of the REEs produced by scavenging reactions can be quite complex.

  7. What about the rare-earth elements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is insufficient understanding of the nutritional physiology of pecan trees and orchards; thus, affecting nutmeat yield and quality, disease resistance and alternate bearing. An analysis of the rare-earth element composition of pecan and related hickory cousins found that they hyperaccumulate ...

  8. Trace element geochemistry of marine biogenic particulate matter

    SciTech Connect

    Collier, R.W.

    1981-02-01

    Plankton samples were investigated for physical and chemical leaching decomposition to identify the major and trace element composition of particulate carrier phases. The identification of trace element/major element ratios in the biogenic materials was emphasized. The majority of the trace elements in the samples were directly associated with the nonskeletal organic phases of the plankton. Calcium carbonate and opal were not significant carriers for any of the trace elements studied. A refractory phase containing Al and Fe in terrigenous ratios was present in all samples, even from the more remote marine locations.

  9. Trace Element Geochemistry of Martian Iddingsite in the Lafayette Meteorite

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Lindstrom, David J.

    1997-01-01

    The Lafayette meteorite contains abundant iddingsite, a fine-grained intergrowth of smectite clay, ferrihydrite, and ionic salt minerals. Both the meteorite and iddingsite formed on Mars. Samples of iddingsite, olivine, and augite pyroxene were extracted from Lafayette and analyzed for trace elements by instrumental neutron activation. Our results are comparable to independent analyses by electron and ion microbeam methods. Abundances of most elements in the iddingsite do not covary significantly. The iddingsite is extremely rich in Hg, which is probably terrestrial contamination. For the elements Si, Al, Fe, Mn, Ni, Co, and Zn, the composition of the iddingsite is close to a mixture of approximately 50% Lafayette olivine + approximately 40% Lafayette siliceous glass + approximately 1O% water. Concordant behavior among these elements is not compatible with element fractionations between smectite and water, but the hydrous nature and petrographic setting of the iddingsite clearly suggest an aqueous origin. These inferences are both consistent, however, with deposition of the iddingsite originally as a silicate gel, which then crystallized (neoformed) nearly isochemically. The iddingsite contains significantly more magnesium than implied by the model, which may suggest that the altering solutions were rich in Mg(2+).

  10. The Role of the Ion Microprobe in Solid-Earth Geochemistry

    NASA Astrophysics Data System (ADS)

    Hauri, E. H.

    2002-12-01

    Despite the early success of the electron microprobe in taking petrology to the micron scale, and the widespread use of mass spectrometers in geochemistry and geochronology, it was not until the mid-1970s that the ion microprobe came into its own as an in situ analytical tool in the Earth sciences. Despite this inauspicious beginning, secondary ion mass spectrometry (SIMS) was widely advertised as a technology that would eventually eclipse thermal ion mass spectrometry (TIMS) in isotope geology. However this was not to happen. While various technical issues in SIMS such as interferences and matrix effects became increasingly clear, an appreciation grew for the complimentary abilities of SIMS and TIMS that, even with the advent of ICP-MS, continues to this day. Today the ion microprobe is capable of abundance measurements in the parts-per-billion range across nearly the entire periodic table, and SIMS stable isotope data quality is now routinely crossing the 1 per mil threshold, all at the micron scale. Much of this success is due to the existence of multi-user community facilities for SIMS research, and the substantial efforts of interested scientists to understand the fundamentals of sputtered ion formation and their application to geochemistry. Recent discoveries of evidence for the existence of ancient crust and oceans, the emergence of life on Earth, the large-scale cycling of surficial materials into the deep Earth, and illumination of fundamental high-pressure phenomena have all been made possible by SIMS, and these (and many more) discoveries owe a debt to the vision of creating and supporting multi-user community facilities for SIMS. The ion microprobe remains an expensive instrument to purchase and maintain, yet it is also exceedingly diverse in application. Major improvements in SIMS, indeed in all mass spectrometry, are visible on the near horizon. Yet the geochemical community cannot depend on commercial manufacturers alone to design and build the next

  11. Rare earth elements and permanent magnets (invited)

    NASA Astrophysics Data System (ADS)

    Dent, Peter C.

    2012-04-01

    Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

  12. Light element geochemistry of the Apollo 12 site

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Kaplan, I. R.; Kung, C. C.; Winter, D. A.; Friedman, D. L.; Desmarais, D. J.

    1978-01-01

    Analytical techniques of improved sensitivity have revealed details of the concentrations and isotopic compositions of light elements for a comprehensive suite of samples from the Apollo 12 regolith. These samples show a wide spread in maturity, although maximum contents observed for solar wind elements are less than observed at other sites, possibly reflecting relative recency of craters at the Apollo 12 site. Isotopic composition of nitrogen is consistent with the idea that N-15/N-14 in the solar wind has increased with time, at least a major part of this increase having occurred in the past 3.1 Gyr. Sulfur isotope systematics support a model in which sulfur is both added to the regolith, by meteoritic influx, and lost, by an isotopically selective process. Most soils from this site are heavily contaminated with terrestrial carbon.

  13. Behavior of Rare Earth Elements in Fractured Aquifers

    NASA Astrophysics Data System (ADS)

    Lee, S.; Kim, Y.; Lee, K.

    2003-12-01

    An understanding of the geochemistry of potential host rocks is very important in the site evaluation for construction of an underground geologic repository for radioactive waste. Because of similar valence and ionic radii and high similarity in electronic structure with trivalent actinides (such as Am3+ and Cm3+), the rare earth elements (REEs) have been used to predict the behavior of actinide-series elements in solution. For Am and Cm, which occur only in the trivalent states in most waste-disposal repository environments, the analogy with the REEs is particularly relevant. Krauskopf calculated the retardation factors for radionuclides in various rock materials based on some compiled data. But, in general, because the transuranic actinides do not occur naturally in appreciable quantities, their behaviors in repository environments cannot be predicted from evidence of their movement in geologic environments (mainly in groundwater) over geologic timespans. Predictions about long-term future behavior of transuranic actinides have therefore been made by extrapolation from short-term observations of their chemical properties in laboratory experiments or in field tests, but such extrapolation is fraught with uncertainty. In order to verify the behavior of Eu in various geological environments, we estimated the abundance of rare earth elements in three gneiss bodies originated from different geological environments and volcanic tuff. We also carried out some leaching experiment of fracture-filling calcite precipitated due to changes of geochemical environment in paleo-groundwater. Of the three gneisses, two gneisses are granitic-granodioritic origin and the other is tonaltic-trondjemitic origin. As a result, we could observe that Eu had a close relationship with fracture-filling calcite precipitation due to water-rock interaction. Our results show that Eu is the most variable element of REEs for the hydrogeological environment such as change of oxidation-reduction and

  14. 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.

  15. 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

  16. Tipping elements in the Earth's climate system

    SciTech Connect

    Lenton, T.M.; Held, H.; Lucht, W.; Rahmstorf, S.; Kriegler, E. |; Hall, J.W.; Schellnhuber, H.J. |

    2008-02-12

    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 the authors introduce the term 'tipping element' to describe large-scale components of the Earth system that may pass a tipping point. They 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 they 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 the authors explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.

  17. [Geochemical characteristics of rare earth elements on sunflower growing area in the west of Jilin Province].

    PubMed

    Li, Shu-Jie; Dou, Sen; Wang, Li-Min; Liu, Zhao-Shun

    2011-07-01

    Soil and plant samples were collected from the sunflower growing area in the west of Jilin province. A variety of ancillary methods were used to determine the soil element content. Then the rare earth elements geochemistry in soil was studied, and the correlation of REEs in this region with other elements and the quality of plant was investigated. The results show that, (1) REE content of the soil in Nong'an is relatively higher to those in Daan and Tongyu. Distribution pattern of rare earth elements in soil for the right tilt of the light rare earth enrichment patterns which is consistent with the national distribution pattern of rare earth elements; (2) REE contents in the three studying areas in the soil are different, and this primarily relates to the soil parent materials; (3) The REEs which positively correlate with soil available potassium are Se, Fe2O3, Ti, P, Mn, Cu, Zn, Cr, Mo, B, F. The protein content of sunflower seeds has a negative correlation with REE. With the exception of Lu, all REEs show a similar correlation.

  18. [In Situ Analysis of Element Geochemistry in Submarine Basalt in Hydrothermal Areas from Ultraslow Spreading Southwest Indian Ridge].

    PubMed

    Wang, Yan; Sun, Xiao-ming; Xu, Li; Liang, Ye-heng; Wu, Zhong-wei; Fu, Yu; Huang, Yi

    2015-03-01

    In this study, we analyze element geochemistry of submarine basalt in situ, which is sampled in hydrothermal areas from ultraslow spreading Southwest Indian Ridge, including the fresh basalt rocks (B19-9, B15-13) and altered basalt (B5-2). And we can confirm that altered mineral in B5-2 is celadonite by microscope and Raman Spectrum. Furthermore, amygdaloidal celadonites are analyzed by electron microprobe (EPMA) and EDS-line scanning. The results show that K-contents decrease and Na-contents increase from the core to the edge in these altered minerals, indicating the transition from celadonite to saponite. Celadonite is an altered minerals, forming in low temperature (< 50 degrees C) and oxidizing condition, while saponite form in low water/rock and more reducing condition. As a result, the transition from celadonite to saponite suggests environment change from oxidizing to reducing condition. Using the result of EPMA as internal standard, we can analyze rare earth elements (REE) in altered mineral in situ. Most of result show positive Eu anomaly (Δ(Eu)), indicating hydrothermal fluid transform from oxidizing to reducing, and reducing fluid rework on the early altered minerals. Comparison with REE in matrix feldspar both in altered and unaltered zoning, we find that reducing fluid can leach REE from the matrix feldspar, leading to lower total REE concentrations and positive Eu anomaly. So leaching process play an important role in hydrothermal system.

  19. 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).

  20. 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.

  1. 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.

  2. Rare Earth Elements in Global Aqueous Media

    NASA Astrophysics Data System (ADS)

    Noack, C.; Karamalidis, A.; Dzombak, D. A.

    2012-12-01

    We are examining the occurrence and abundance of rare earth elements (REE) associated with produced waters from shale gas development, and factors controlling aqueous REE concentrations in geochemical environments, to provide information for: (1) potential recovery of REE as a valuable byproduct, and (2) utilization of unique REE signatures as a risk assessment tool. REE include the lanthanide series of elements - excluding short-lived, radioactive promethium - and yttrium. These elements are critical to a wide variety of high-tech, energy efficient applications such as phosphors, magnets, and batteries. Escalating costs of REE resulting from divergent supply and demand patterns motivates the first goal. The second goal relates to the search for a reliable, naturally occurring tracer to improve understanding of fluid migration and water-rock interactions during hydraulic fracturing and natural gas recovery. We compiled data from 100 studies of REE occurrence and concentrations in groundwaters, ocean waters, river waters, and lake waters. In the groundwater systems documented, total dissolved REE concentrations ranged over eight orders of magnitude; however the average concentrations across the lanthanides varied by less than two orders of magnitude. This leads to exceptional inter-element correlations, with a median correlation coefficient greater than 0.98, implying potential usefulness of REE ratios for groundwater signatures. Reports describing reactions governing REE solubilization were also investigated. We assembled information about important solution chemistries and performed equilibrium modeling using PHREEQC to examine common hypotheses regarding the factors controlling REE compositions. In particular, effects of pH, Eh, and common complexing ligands were evaluated. Produced and connate waters of the Marcellus shale are well characterized for their major chemical elements. There is a dearth of knowledge, however, regarding the occurrence of REE in

  3. Trace Elemental Geochemistry of Pacific Margin Seep and Non-seep Benthic Foraminifera

    NASA Astrophysics Data System (ADS)

    Burkett, A. M.; Rathburn, A. E.; De Deckker, P.; Perez, M. E.

    2015-12-01

    As part of a continued effort to evaluate factors that influence carbonate biogeochemistry of living foraminifera, stable isotopic and trace elemental analyses of epibenthic and infaunal species of benthic foraminifera collected from the Pacific margin revealed clues for assessment of the presence, history and origin of cold and hydrothermal methane seepage sites. Hydrothermal seeps have only recently been discovered, prioritizing their recognition and assessments of the origins/sources of these anomalously warm environments. Trace elements were analyzed with a laser ablation ICP-MS at the Australian National University, avoiding contamination and allowing measurements of recently generated chambers. Living Cibicidoides wuellerstorfi and Uvigerina peregrina collected from active methane seeps on the east Pacific margin (Costa Rica, Alaska and Hydrate Ridge) have a wider range in both stable isotopic signals and some trace elemental values (e.g., Mg/Ca) compared to nearby inactive areas. Comparisons of additional trace elemental values (e.g., Li/Ca, Cd/Ca, B/Ca, and Ba/Ca) from living Cibicidoides wuellerstorfi and Uvigerina peregrina from these unique seafloor environments provide additional information in the geochemical influences of cold and hydrothermal seepage on foraminiferal calcite geochemistry. Seep environments are often the result of complex tectonic processes, have implications in past rapid climatic shifts and in future climate change predictions and models, and can influence modern ecosystems and biogeochemical cycles in ways which are not fully understood. Benthic foraminiferal geochemistry provides a potential means to identify seep fluid origins, elucidate seep fluid records and recognize hydrothermal seeps and their spatial and temporal history.

  4. Google Earth locations of USA and seafloor hydrothermal vents with associated rare earth element data

    SciTech Connect

    Andrew Fowler

    2016-02-10

    Google Earth .kmz files that contain the locations of geothermal wells and thermal springs in the USA, and seafloor hydrothermal vents that have associated rare earth element data. The file does not contain the actual data, the actual data is available through the GDR website in two tier 3 data sets entitled "Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge (MOR) Hydrothermal Vents" and "Rare earth element content of thermal fluids from Surprise Valley, California"

  5. Trace-element geochemistry of coal resource development related to environmental quality and health

    SciTech Connect

    Not Available

    1980-01-01

    This report assesses for decision makers and those involved in coal resource development the environmental and health impacts of trace-element effects arising from significant increases in the use of coal, unless unusual precautions are invoked. Increasing demands for energy and the pressing need for decreased dependence of the United States on imported oil require greater use of coal to meet the nation's energy needs during the next decade. If coal production and consumption are increased at a greatly accelerated rate, concern arises over the release, mobilization, transportation, distribution, and assimilation of certain trace elements, with possible adverse effects on the environment and human health. It is, therefore, important to understand their geochemical pathways from coal and rocks via air, water, and soil to plants, animals, and ultimately humans, and their relation to health and disease. To address this problem, the Panel on Trace Element Geochemistry of Coal Resource Development Related to Health (PECH) was established. Certain assumptions were made by the Panel to highlight the central issues of trace elements and health and to avoid unwarranted duplication of other studies. Based on the charge to the Panel and these assumptions, this report describes the amounts and distribution of trace elements related to the coal source; the various methods of coal extraction, preparation, transportation, and use; and the disposal or recycling of the remaining residues or wastes. The known or projected health effects are discussed at the end of each section.

  6. Catalog of Mount St. Helens 2004 - 2005 Tephra Samples with Major- and Trace-Element Geochemistry

    USGS Publications Warehouse

    Rowe, Michael C.; Thornber, Carl R.; Gooding, Daniel J.; Pallister, John S.

    2008-01-01

    This open-file report presents a catalog of information about 135 ash samples along with geochemical analyses of bulk ash, glass and individual mineral grains from tephra deposited as a result of volcanic activity at Mount St. Helens, Washington, from October 1, 2004 until August 15, 2005. This data, in conjunction with that in a companion report on 2004?2007 Mount St. Helens dome samples by Thornber and others (2008a) are presented in support of the contents of the U.S. Geological Survey Professional Paper 1750 (Sherrod and others, ed., 2008). Readers are referred to appropriate chapters in USGS Professional Paper 1750 for detailed narratives of eruptive activity during this time period and for interpretations of sample characteristics and geochemical data presented here. All ash samples reported herein are currently archived at the David A. Johnston Cascades Volcano Observatory in Vancouver, Washington. The Mount St. Helens 2004?2005 Tephra Sample Catalogue along with bulk, glass and mineral geochemistry are tabulated in 6 worksheets of the accompanying Microsoft Excel file, of2008-1131.xls. Samples in all tables are organized by collection date. Table 1 is a detailed catalog of sample information for tephra deposited downwind of Mount St. Helens between October 1, 2004 and August 18, 2005. Table 2 provides major- and trace-element analyses of 8 bulk tephra samples collected throughout that interval. Major-element compositions of 82 groundmass glass fragments, 420 feldspar grains, and 213 mafic (clinopyroxene, amphibole, hypersthene, and olivine) mineral grains from 12 ash samples collected between October 1, 2004 and March 8, 2005 are presented in tables 3 through 5. In addition, trace-element abundances of 198 feldspars from 11 ash samples (same samples as major-element analyses) are provided in table 6. Additional mineral and bulk ash analyses from 2004 and 2005 ash samples are published in chapters 30 (oxide thermometry; Pallister and others, 2008), 32

  7. Rare earths and other trace elements in Luna 16 soil.

    NASA Technical Reports Server (NTRS)

    Helmke, P. A.; Haskin, L. A.

    1972-01-01

    An analysis has been made of four small samples of material brought to earth by the Luna 16 mission, with the aim to determine rare earths and other trace elements in these samples. The analytical results are tabulated, and the rare earth abundances are compared with the average for chondrites. A comparison is also made with the results of similar analyses of Apollo samples.

  8. How PNNL Extracts Rare Earth Elements from Geothermal Brine

    SciTech Connect

    2016-07-12

    By looking at a problem at a nanoscale level, PNNL researchers are developing an economic way to extract valuable rare earth elements from geothermal fluids. This novel approach may help meet the high demand for rare earth elements that are used in many clean energy technologies.

  9. Rare earth element diffusion in natural enstatite

    NASA Astrophysics Data System (ADS)

    Cherniak, Daniele J.; Liang, Yan

    2007-03-01

    diopside [Van Orman, J.A., Grove, T.L., Shimizu, N., 2001. Rare earth element diffusion in diopside; influence of temperature, pressure, and ionic radius, and an elastic model for diffusion in silicates. Contrib. Mineral. Petrol.141, 687-703]. These differences in diffusive behavior of REE between diopside and enstatite, as well as Eu 2+ and Eu 3+ in enstatite, can result in significant REE fractionation between coexisting pyroxenes during partial melting, melt migration, and subsolidus reequilibration processes in the Earth's mantle and that of the Moon.

  10. Rare earth elements in Hamersley BIF minerals

    NASA Astrophysics Data System (ADS)

    Alibert, Chantal

    2016-07-01

    Minerals from the Hamersley banded iron formation, Western Australia, were analyzed for Y and rare earth elements (YREEs) by laser ablation ICP-MS to investigate diagenetic pathways, from precursor phases to BIF minerals. One group of apatites carries the seawater REE signature, giving evidence that P and REEs, thoroughly scavenged from the water column by Si-ferrihydrite particles, were released upon microbial Fe3+ reductive dissolution of Si-ferrihydrite in pore-water and finally sequestered mainly in authigenic apatite. The absence of fractionation between apatite and seawater suggests that REE were first incorporated into an amorphous calcium phosphate as fully hydrated cations, i.e. as outer-sphere complexes. The iron oxides and carbonates carry only a small fraction of the whole-rock REE budget. Their REE patterns are distinctly enriched in Yb and show some M-type tetrad effect consistent with experimental Kd(REE) between solid and saline solution with low carbonate ion concentrations. It is deduced that hematite formed at an incipient stage of Fe2+-catalyzed dissolution of Si-ferrihydrite, via a dissolution-reprecipitation pathway. The REE pattern of greenalite, found as sub-micron particles in quartz in a chert-siderite sample, is consistent with its authigenic origin by precipitation in pore-water after dissolution of a small amount of Si-ferrihydrite. Magnetite carries very low YREEs (ppb-level), has an homogeneous pattern distinctly enriched in the mid-REEs compared to hematite, and includes a late population depleted in light-REEs, Ba and As. Magnetite forming aggregates and massive laminae is tentatively interpreted as reflecting some fluid-aided hematite-magnetite re-equilibration or transformation at low-grade metamorphic temperatures.

  11. [Content of rare earth elements in wild Hypericum japonicum Thunb].

    PubMed

    Wei, Zhen-Lin; Rui, Yu-Kui; Tian, Zhi-Huan

    2009-06-01

    Rare earth elements are important nutritional elements for human health, and today more and more attention has been paid to the effective components in Chinese traditional medicine, especially to rare earth elements. Fifteen rare earth elements in wild hypericum japonicum Thunb were analyzed by the methods of ICP-MS. The results showed that the concentrations of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Tm, Lu and Y ranged from 6 ng x g(-1) x DW to 14 522 ng x g(-1) x DW, and among them the concentrations of La, Ce and Nd were higher than 2 000 ng x g(-1) x DW. Compared with the concentration of rare earth elements in rice, corn, wheat and barley, the total concentration of rare earth elements in hypericum japonicum Thunb was much higher, which could be the mechanism of curative effect of hypericum japonicum Thunb on liverish diseases. The character of elements and the content of rare earth elements in soil should be responsible for the difference, but the distributive mechanism of rare earth elements in hypericum japonicum Thunb should be further studied.

  12. Paragneiss zircon geochronology and trace element geochemistry, North Qaidam HP/UHP terrane, western China

    USGS Publications Warehouse

    Mattinson, C.G.; Wooden, J.L.; Zhang, J.X.; Bird, D.K.

    2009-01-01

    In the southeastern part of the North Qaidam terrane, near Dulan, paragneiss hosts minor peridotite and UHP eclogite. Zircon geochronology and trace element geochemistry of three paragneiss samples (located within a ???3 km transect) indicates that eclogite-facies metamorphism resulted in variable degrees of zircon growth and recrystallization in the three samples. Inherited zircon core age groups at 1.8 and 2.5 Ga suggest that the protoliths of these rocks may have received sediments from the Yangtze or North China cratons. Mineral inclusions, depletion in HREE, and absence of negative Eu anomalies indicate that zircon U-Pb ages of 431 ?? 5 Ma and 426 ?? 4 Ma reflect eclogite-facies zircon growth in two of the samples. Ti-in-zircon thermometry results are tightly grouped at ???660 and ???600 ??C, respectively. Inclusions of metamorphic minerals, scarcity of inherited cores, and lack of isotopic or trace element inheritance demonstrate that significant new metamorphic zircon growth must have occurred. In contrast, zircon in the third sample is dominated by inherited grains, and rims show isotopic and trace element inheritance, suggesting solid-state recrystallization of detrital zircon with only minor new growth. ?? 2009 Elsevier Ltd.

  13. Geochemistry of trace elements in coals from the Zhuji Mine, Huainan Coalfield, Anhui, China

    USGS Publications Warehouse

    Sun, R.; Liu, Gaisheng; Zheng, Lingyun; Chou, C.-L.

    2010-01-01

    The abundances of nine major elements and thirty-eight trace elements in 520 samples of low sulfur coals from the Zhuji Mine, Huainan Coalfield, Anhui, China, were determined. Samples were mainly collected from 10 minable coal seams of 29 boreholes during exploration. The B content in coals shows that the influence of brackish water decreased toward the top of coal seams; marine transgression and regression occurred frequently in the Lower Shihezi Formation. A wide range of elemental abundances is found. Weighted means of Na, K, Fe, P, Be, B, Co, Ni, Cr, Se, Sb, Ba, and Bi abundances in Zhuji coals are higher, and the remainder elements are either lower or equal to the average values of elements in coals of northern China. Compared to the Chinese coals, the Zhuji coals are higher in Na, K, Be, B, Cr, Co, Se, Sn, Sb, and Bi, but lower in Ti, P, Li, V and Zn. The Zhuji coals are lower only in S, P, V and Zn than average U.S. and world coals. Potassium, Mg, Ca, Mn, Sr, As, Se, Sb and light rare earth elements (LREE) had a tendency to be enriched in thicker coal seams, whereas Fe, Ti, P, V, Co, Ni, Y, Mo, Pb and heavy rare earth elements (HREE) were inclined to concentrate in thinner coal seams. The enrichment of some elements in the Shanxi or Upper Shihezi Formations is related to their depositional environments. The elements are classified into three groups based on their stratigraphic distributions from coal seams 3 to 11-2, and the characteristics of each group are discussed. Lateral distributions of selected elements are also investigated. The correlation coefficients of elemental abundances with ash content show that the elements may be classified into four groups related to modes of occurrence of these elements. ?? 2009 Elsevier B.V. All rights reserved.

  14. 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.

  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. Rare earth element enrichment using membrane based solvent extraction

    NASA Astrophysics Data System (ADS)

    Makertiharta, I. G. B. N.; Dharmawijaya, P. T.; Zunita, M.; Wenten, I. G.

    2017-01-01

    The chemical, catalytic, electrical, magnetic, and optical properties of rare earth elements are required in broad applications. Rare earth elements have similar physical and chemical properties thus it is difficult to separate one from each other. Rare earth element is relatively abundant in earth's crust but rarely occur in high concentrated deposits. Traditionally, ion-exchange and solvent extraction techniques have been developed to separate and purify single rare earth solutions or compounds. Recently, membrane starts to gain attention for rare earth separation by combining membrane and proven technologies such as solvent extraction. Membrane-based process offers selective, reliable, energy efficient and easy to scale up separation. During membrane-based separation process, one phase passes through membrane pores while the other phase is rejected. There is no direct mixing of two phases thus the solvent loss is very low. Membrane can also lower solvent physical properties requirement (viscosity, density) and backmixing, eliminate flooding phenomenon and provide large interfacial area for mass transfer. This paper will summarize research efforts in developing membrane technology for rare earth element separation. Special attention will be given to solvent extraction related process as the commonly used method for rare earth element separation. Furthermore, membrane configuration and its potentials will also be discussed.

  17. Trace-element geochemistry of postorogenic granites from the northeastern Arabian Shield, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Stuckless, John S.; Knight, R.J.; VanTrump, G.; Budahn, J.R.

    1983-01-01

    Concentrations determined for all of the trace elements included in this study of postorogenic granites from the northeastern Arabian Shield are best described by log-normal distributions. The trace elements are divided into two groups: (1) compatible lithophile and siderophile elements (strontium, cobalt, scandium, manganese, europium, and titanium) and (2) incompatible lithophile elements (uranium, thorium, tantalum, rubidium, and rare-earth elements, except europium). The compatible elements exhibit greatest concentrations in the metaluminous postorogenic granites, and concentrations decrease with increasing degree of magma evolution. Economic potential for these elements and other geochemically similar elements is considered to be low. The concentrations of the incompatible elements increase with increasing degree of magma evolution and are greatest in the peralkaline and peraluminous granites. There is some geologic evidence that pegmatite and vein-forming processes were operative toward the end stage of postorogenic magmatism in the northeastern Arabian Shield, and therefore there is some probability for economic potential for these elements. It is suggested that such potential is greatest where highly evolved postorogenic granites intruded volatile (generally water )-rich country rocks.

  18. Archean granulite gneisses from eastern Hebei Province, China: rare earth geochemistry and tectonic implications

    NASA Astrophysics Data System (ADS)

    Jahn, Bor-Ming; Zhang, Zong-Qing

    1984-03-01

    The granulite gneisses and their retrograded products of the Qianxi Group from eastern Hebei Province, China, have been investigated for their isotope and trace element geochemistry. A consistent age of about 2.5 AE has been obtained by the Rb-Sr and Sm-Nd whole-rock isochron methods, in agreement with the zircon U-Pb data (Pidgeon 1980; D.Y. Liu, unpubl.). Geochemical arguments from initial isotopic ratios (ISr and INd) and elemental distribution patterns have led us to conclude that this age of about 2.5 AE represents the time of granulite facies metamorphism, which must have followed closely the primary emplacement of their protoliths. Previous claims for early Archean ages (>3.5 AE) of these granulites are not substantiated. The mineral isotope systematics register an important thermal event at about 1.7 AE, roughly corresponding to the time of the widespread Luliang Orogeny (Ma and Wu 1981) or Chungtiao Movement (Huang 1978). The granulites of the Qianxi Group have diverse compositions ranging from ultrabasic through basic-intermediate to acid. Discriminant function calculations suggest that most analyzed samples have igneous parentage. Only a few show characteristics of metasedimentary rocks. The igneous protoliths apparently belong to two series — tholeiitic and calc-alkaline, with the latter dominating in abundance. The majority of the acid granulites have compositions corresponding to tonalite-granodiorite. Except for ultrabasic and metasedimentary rocks, all REE patterns are significantly fractionated with LREE enrichment. The degree of fractionation, as measured by the (La/Yb)N ratios, is most important in the acid granulites. These rocks often show positive Eu anomalies and HREE depletions that are typical of Archean TTG rocks (tonalitetrondhjemite-granodiorite). The existence of komatiites has been previously reported in this region. Although a few rocks have a major element chemistry similar to that for peridotitic komatiites, the lack of associated

  19. Implications of Competition for Rare Earth Elements (REE) in Africa

    DTIC Science & Technology

    2011-03-15

    Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202- 4302. Respondents should be aware that...2010). 3 Marc Humphries , ―Rare Earth Elements: The Global Supply Chain,‖ Congressional Research Service Report for Congress R41347 (September 30...101026_Verrastro_Geopolitics_web.pdf (accessed October 14, 2010). 10 Humphries , ―Rare Earth Elements: The Global Supply Chain,‖ (September 30, 2010): 4

  20. Highly siderophile elements in Earth's mantle as a clock for the Moon-forming impact.

    PubMed

    Jacobson, Seth A; Morbidelli, Alessandro; Raymond, Sean N; O'Brien, David P; Walsh, Kevin J; Rubie, David C

    2014-04-03

    According to the generally accepted scenario, the last giant impact on Earth formed the Moon and initiated the final phase of core formation by melting 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 Myr) 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 and the Grand Tack scenario of terrestrial planet formation, and holds across a wide range of disk conditions. The concentration of highly siderophile elements (HSEs) in Earth's mantle constrains the mass of chondritic material added to Earth during Late Accretion. Using HSE abundance measurements, we determine a Moon-formation age of 95 ± 32 Myr after condensation. The possibility exists that some late projectiles were differentiated and left an incomplete HSE record in Earth's mantle. Even in this case, various isotopic constraints strongly suggest that the late-accreted mass did not exceed 1 per cent of Earth's mass, and so the HSE clock still robustly limits the timing of the Moon-forming event to significantly later than 40 Myr after condensation.

  1. Experimental geochemistry of Pu and Sm and the thermodynamics of trace element partitioning

    NASA Technical Reports Server (NTRS)

    Jones, John H.; Burnett, Donald S.

    1987-01-01

    An experimental study of the partitioning of Pu and Sm between diopside/liquid and whitlockite/liquid supports the hypothesis that Pu behaves as a light rare earth element during igneous processes in reducing environments. D-Pu/D-Sm is found to be about 2 for both diopsidic pyroxene and whitlockite, and the amount of fractionation would be decreased further if Pu were compared to Ce or Nd. Data indicate that temperature, rather than melt composition, is the most important control on elemental partitioning, and that P2O5 in aluminosilicate melts serves as a complexing agent for the actinides and lanthanides.

  2. Trace Element and As Geochemistry of Surface Waters around Mammoth Mountain, CA

    NASA Astrophysics Data System (ADS)

    Hunt, K. M.; Ellis, A. S.; Raskin, S.; Khachikian, C.

    2012-12-01

    Mammoth Mountain has been studied because of high CO2 emissions since a 1989 earthquake swarm. The current study is part of ongoing research that is investigating the relationship between the elevated CO2 and the mountain's hydrosphere and mineral weathering. This project builds upon previous analyses of major ion chemistry of Mammoth Mountain springs by analyzing the trace element and contaminant geochemistry. Analyses show variations in both trace/minor elements and contaminants. Sr values vary from less than 0.04 to more than 200(μg/L), and are positively correlated to Ca. Sr and Ca have similar chemical behavior and Sr can replace Ca in silicate minerals. Globally, waters draining silicates have low Ca/Na and Sr/Na ratios (Gaillardet et. Al 1999). Molar ratios for the springs in this study plot on a mixing line between the largely felsic silicates known to compose the area around Mammoth Mountain and the more mafic silicates in the Devils Post Pile area. However, the Sr/Na ratio was high, causing the values to shift to the right of Gaillardet's line for global silicate weathering. This may indicate differential mineral weathering but more research is necessary. Arsenic is present in values ranging from less than 0.03 to more than 200(μg/L). The U.S EPA maximum contaminant level for As is 10ppb and six sample locations were above the MCL. A study of Eastern Sierra Nevada rivers shows that possible sources of As are weathering of As-rich rocks, volcanic deposits, and input of high-As geothermal spring waters (Johannesson et al. 1997). In Hot Creek, located in the Owens Valley near Mammoth Mountain, elevated As concentrations have been shown to be the result of geothermal inputs (Hering 1997).

  3. Volcanism in the Sumisu Rift, I. Major element, volatile, and stable isotope geochemistry

    USGS Publications Warehouse

    Hochstaedter, A.G.; Gill, J.B.; Kusakabe, M.; Newman, S.; Pringle, M.; Taylor, B.; Fryer, P.

    1990-01-01

    A bimodal volcanic suite with KAr ages of 0.05-1.40 Ma was collected from the Sumisu Rift using alvin. These rocks are contemporaneous with island arc tholeiite lavas of the Izu-Ogasawara arc 20 km to the east, and provide a present day example of volcanism associated with arc rifting and back-arc basin initiation. Major element geochemistry of the basalts is most similar to that of basalts found in other, more mature back-arc basins, which indicates that back-arc basins need not begin their magmatic evolution with lavas bearing strong arc signatures. Volatile concentrations distinguish Sumisu Rift basalts from island arc basalts and MORB. H2O contents, which are at least four times greater than in MORB, suppress plagioclase crystallization. This suppression results in a more mafic fractionating assemblage, which prevents Al2O3 depletion and delays the initiation of Fe2O3(tot) and TiO2 enrichment. However, unlike arc basalts, Fe3+ ??Fe ratios are only slightly higher than in MORB and are insufficient to cause magnetite saturation early enough to suppress Fe2O3(tot) and TiO2 enrichment. Thus, major element trends are more similar to those of MORB than arcs. H2O, CO2 and S are undersaturated relative to pure phase solubility curves, indicating exsolution of an H2O-rich mixed gas phase. High H2O S, high ??D, and low (MORB-like) ??34S ratios are considered primary and distinctive of the back-arc basin setting. ?? 1990.

  4. Evidence against a chondritic Earth.

    PubMed

    Campbell, Ian H; O'Neill, Hugh St C

    2012-03-28

    The (142)Nd/(144)Nd ratio of the Earth is greater than the solar ratio as inferred from chondritic meteorites, which challenges a fundamental assumption of modern geochemistry--that the composition of the silicate Earth is 'chondritic', meaning that it has refractory element ratios identical to those found in chondrites. The popular explanation for this and other paradoxes of mantle geochemistry, a hidden layer deep in the mantle enriched in incompatible elements, is inconsistent with the heat flux carried by mantle plumes. Either the matter from which the Earth formed was not chondritic, or the Earth has lost matter by collisional erosion in the later stages of planet formation.

  5. 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.

  6. Bioleaching of rare earth elements from monazite sand.

    PubMed

    Brisson, Vanessa L; Zhuang, Wei-Qin; Alvarez-Cohen, Lisa

    2016-02-01

    Three fungal strains were found to be capable of bioleaching rare earth elements from monazite, a rare earth phosphate mineral, utilizing the monazite as a phosphate source and releasing rare earth cations into solution. These organisms include one known phosphate solubilizing fungus, Aspergillus niger ATCC 1015, as well as two newly isolated fungi: an Aspergillus terreus strain ML3-1 and a Paecilomyces spp. strain WE3-F. Although monazite also contains the radioactive element Thorium, bioleaching by these fungi preferentially solubilized rare earth elements over Thorium, leaving the Thorium in the solid residual. Adjustments in growth media composition improved bioleaching performance measured as rare earth release. Cell-free spent medium generated during growth of A. terreus strain ML3-1 and Paecilomyces spp. strain WE3-F in the presence of monazite leached rare earths to concentrations 1.7-3.8 times those of HCl solutions of comparable pH, indicating that compounds exogenously released by these organisms contribute substantially to leaching. Organic acids released by the organisms included acetic, citric, gluconic, itaconic, oxalic, and succinic acids. Abiotic leaching with laboratory prepared solutions of these acids was not as effective as bioleaching or leaching with cell-free spent medium at releasing rare earths from monazite, indicating that compounds other than the identified organic acids contribute to leaching performance.

  7. 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.

  8. Major and trace element geochemistry of S-type cosmic spherules

    NASA Astrophysics Data System (ADS)

    Rudraswami, N. G.; Shyam Prasad, M.; Babu, E. V. S. S. K.; Vijaya Kumar, T.

    2016-04-01

    Micrometeorites that pass through the Earth's atmosphere undergo changes in their chemical compositions, thereby making it difficult to understand if they are sourced from the matrix, chondrules, or calcium-aluminum-rich inclusions (CAIs). These components have the potential to provide evidence toward the understanding of the early solar nebular evolution. The variations in the major element and trace element compositions of 155 different type (scoriaceous, relict bearing, porphyritic, barred, cryptocrystalline, and glass) of S-type cosmic spherules are investigated with the intent to decipher the parent sources using electron microprobe and laser ablation inductively coupled plasma-mass spectrometry. The S-type cosmic spherules appear to show a systematic depletion in volatile element contents, but have preserved their refractory trace elements. The trends in their chemical compositions suggest that the S-type spherules comprise of components from similar parent bodies, that is, carbonaceous chondrites. Large fosteritic relict grains observed in this investigation appear to be related to the fragments of chondrules from carbonaceous chondrites. Furthermore, four spherules (two of these spherules enclose spinels and one comprised entirely of a Ca-Al-rich plagioclase) show enhanced trace element enrichment patterns that are drastically different from all the other 151 cosmic spherules. The information on the chemical composition and rare earth elements (REEs) on cosmic spherules suggest that the partially to fully melted ones can preserve evidences related to their parent bodies. The Ce, Eu, and Tm anomalies found in the cosmic spherules have similar behavior as that of chondrites. Distinct correlations observed between different REEs and types of cosmic spherules reflect the inherited properties of the precursors.

  9. Modeling rammed earth wall using discrete element method

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.

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

    USGS Publications Warehouse

    Murata, K.J.; Rose, H.J.; 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

  11. Alkali elements in the Earth's core: Evidence from enstatite meteorites

    NASA Technical Reports Server (NTRS)

    Lodders, K.

    1995-01-01

    The abundances of alkali elements in the Earth's core are predicted by assuming that accretion of the Earth started from material similar in composition to enstatite chondrites and that enstatite achondrites (aubrites) provide a natural laboratory to study core-mantle differentiation under extremely reducing conditions. If core formation on the aubrite parent body is comparable with core formation on the early Earth, it is found that 2600 (+/- 1000) ppm Na, 550 (+/- 260) ppm K, 3.4 (+/- 2.1) ppm Rb, and 0.31 (+/- 0.24) ppm Cs can reside in the Earth's core. The alkali-element abundances are consistent with those predicted by independent estimates based on nebula condensation calculations and heat flow data.

  12. Magnetic Nanofluid Rare Earth Element Extraction Process Report, Techno Economic Analysis, and Results for Geothermal Fluids

    SciTech Connect

    Pete McGrail

    2016-03-14

    This GDR submission is an interim technical report and raw data files from the first year of testing on functionalized nanoparticles for rare earth element extraction from geothermal fluids. The report contains Rare Earth Element uptake results (percent removal, mg Rare Earth Element/gram of sorbent, distribution coefficient) for the elements of Neodymium, Europium, Yttrium, Dysprosium, and Cesium. A detailed techno economic analysis is also presented in the report for a scaled up geothermal rare earth element extraction process. All rare earth element uptake testing was done on simulated geothermal brines with one rare earth element in each brine. The rare earth element uptake testing was conducted at room temperature.

  13. Minor-element and Sr-isotope geochemistry of tertiary stocks, Colorado mineral belt

    USGS Publications Warehouse

    Simmons, E.C.; Hedge, C.E.

    1978-01-01

    Rocks of the northeast portion of the Colorado mineral belt form two petrographically, chemically and geographically distinct rock suites: (1) a silica oversaturated granodiorite suite; and (2) a silica saturated, high alkali monzonite suite. Rocks of the granodiorite suite generally have Sr contents less than 1000 ppm, subparallel REE patterns and initial 87Sr/ 86Sr ratios greater than 0.707. Rocks of the monzonite suite are restricted to the northeast part of the mineral belt, where few rocks of the granodiorite suite occur, and generally have Sr contents greater than 1000 ppm, highly variable REE patterns and 87Sr/86Sr initial ratios less than 0.706. Despite forming simple, smooth trends on major element variation diagrams, trace element data for rocks of the granodiorite suite indicate that they were not derived from a single magma. These rocks were derived from magmas having similar REE patterns, but variable Rb and Sr contents, and Rb/Sr ratios. The preferred explanation for these rocks is that they were derived by partial melting of a mixed source, which yielded pyroxene granulite or pyroxenite residues. The monzonite suite is chemically and petrographically more complex than the granodiorite suite. It is subdivided here into alkalic and mafic monzonites, and quartz syenites, based on the textural relations of their ferromagnesian phases and quartz. The geochemistry of these three rock types require derivation from separate and chemically distinct magma types. The preferred explanation for the alkalic monzonites is derivation from a heterogeneous mafic source, leaving a residue dominated by garnet and clinopyroxene. Early crystallization of sphene from these magmas was responsible for the severe depletion of the REE observed in the residual magmas. The lower Sr content and higher Rb/Sr ratios of the mafic monzonites requires a plagioclase-bearing source. The Sr-isotope systematics of the majority of these rocks are interpreted to be largely primary, and not

  14. 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.

  15. Rare Earth Elements in National Defense: Background, Oversight Issues, and Options for Congress

    DTIC Science & Technology

    2011-03-31

    light rare earths (lanthanum, cerium, praseodymium , neodymium, promethium, samarium) and heavy rare earths (europium, gadolinium, terbium, dysprosium...rare earth elements cerium, lanthanum, praseodymium , and neodymium. However, the Mountain Pass mine will not immediately be able to refine rare earth

  16. Hf-Nd Isotopic and Trace-Element Geochemistry of Global Subducting Sediments

    NASA Astrophysics Data System (ADS)

    Vervoort, J. D.; Plank, T.; Patchett, P. J.

    2001-12-01

    Ferromanganese nodules, crusts, and associated metalliferous clays have long been known to have anomalously high Lu/Hf ratios and highly radiogenic Hf relative to Nd (Patchett et al., 1984; White et al., 1986). These oceanic sediments are some of the few terrestrial materials where Hf and Nd isotopes deviate from the crust-mantle array. This distinctive isotopic signature, therefore, has the potential to trace the fate of oceanic sediments through the subduction zone and into the mantle. It has recently been suggested, for example, that pelagic sediments can be detected in some Hawaiian basalts (Blichert-Toft et al., 1999) and in volcanic rocks from the Luzon arc (Marini et al., 2000) based on their Hf-Nd isotopic compositions. The weak link in this approach, however, is that we do not know, in any quantitative way, how widespread this anomalous signature is in oceanic sediments, what compositions are responsible for this signature, or how volumetrically important these compositions are in terms of the total sediment flux into subduction zones and the mantle. Most marine sediments analyzed thus far have been collected on or near the ocean floor and constitute an incomplete and unrepresentative inventory of the sediment column bound for the subduction zone. There is some reason to suspect that much of the sediment flux is not particularly anomalous, either in terms of Lu/Hf ratios or Hf and Nd isotopic compositions. The most dominant sediment types entering many subduction zones (terrigenous and other continentally derived sediments), have normal Lu/Hf ratios and Hf-Nd isotopic compositions that are indistinguishable from the crust-mantle array. An examination is needed of the Hf-Nd isotopic composition of oceanic sediments, the major and trace-element geochemistry of global sediment flux, how such compositions may relate to Hf-Nd isotopic behavior, and potential Lu/Hf and Nd/Hf fractionation in subduction zones. In addition, the origin of the high Lu/Hf and

  17. 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 0.75 kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79 kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium.

  18. Heterogeneous accretion and the moderately volatile element budget of Earth.

    PubMed

    Schönbächler, M; Carlson, R W; Horan, M F; Mock, T D; Hauri, E H

    2010-05-14

    Several models exist to describe the growth and evolution of Earth; however, variables such as the type of precursor materials, extent of mixing, and material loss during accretion are poorly constrained. High-precision palladium-silver isotope data show that Earth's mantle is similar in 107Ag/109Ag to primitive, volatile-rich chondrites, suggesting that Earth accreted a considerable amount of material with high contents of moderately volatile elements. Contradictory evidence from terrestrial chromium and strontium isotope data are reconciled by heterogeneous accretion, which includes a transition from dominantly volatile-depleted to volatile-rich materials with possibly high water contents. The Moon-forming giant impact probably involved the collision with a Mars-like protoplanet that had an oxidized mantle, enriched in moderately volatile elements.

  19. Sulfide Mineralogy and Geochemistry

    NASA Astrophysics Data System (ADS)

    Dilles, John

    2007-02-01

    Reviews in Mineralogy and Geochemistry Series, Volume 61 David J. Vaughan, Editor Geochemical Society and Mineralogical Society of America; ISBN 0-939950-73-1 xiii + 714 pp.; 2006; $40. Sulfide minerals as a class represent important minor rock-forming minerals, but they are generally known as the chief sources of many economic metallic ores. In the past two decades, sulfide research has been extended to include important roles in environmental geology of sulfide weathering and resultant acid mine drainage, as well as in geomicrobiology in which bacteria make use of sulfides for metabolic energy sources. In the latter respect, sulfides played an important role in early evolution of life on Earth and in geochemical cycling of elements in the Earth's crust and hydrosphere.

  20. Uranium, thorium and rare earth elements in macrofungi: what are the genuine concentrations?

    PubMed

    Borovička, Jan; Kubrová, Jaroslava; Rohovec, Jan; Randa, Zdeněk; Dunn, Colin E

    2011-10-01

    Concentrations of uranium, thorium and rare earth elements (REE) in 36 species of ectomycorrhizal (26 samples) and saprobic (25 samples) macrofungi from unpolluted sites with differing bedrock geochemistry were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Analytical results are supported by use of certified reference materials (BCR-670, BCR-667, NIST-1575a) and the reliability of the determination of uranium was verified by epithermal neutron activation analysis (ENAA). It appears that data recently published on these elements are erroneous, in part because of use of an inappropriate analytical method; and in part because of apparent contamination by soil particles resulting in elevated levels of thorium and REE. Macrofungi from unpolluted areas, in general, did not accumulate high levels of the investigated metals. Concentrations of uranium and thorium were generally below 30 and 125 μg kg(-1) (dry weight), respectively. Concentrations of REE in macrofungi did not exceed 360 μg kg(-1) (dry weight) and their distribution more or less followed the trend observed in post-Archean shales and loess.

  1. Trace element geochemistry of groundwater in a karst subterranean estuary (Yucatan Peninsula, Mexico)

    NASA Astrophysics Data System (ADS)

    Gonneea, Meagan Eagle; Charette, Matthew A.; Liu, Qian; Herrera-Silveira, Jorge A.; Morales-Ojeda, Sara M.

    2014-05-01

    Trace element cycling within subterranean estuaries frequently alters the chemical signature of groundwater and may ultimately control the total chemical load to the coastal ocean associated with submarine groundwater discharge. Globally, karst landscapes occur over 12% of all coastlines. Subterranean estuaries in these regions are highly permeable, resulting in rapid infiltration of precipitation and transport of groundwater to the coast, and the predominant carbonate minerals are readily soluble. We studied the chemical cycling of barium (Ba), strontium (Sr), manganese (Mn), uranium (U), calcium (Ca) and radium (Ra) within the carbonate karst subterranean estuary of the Yucatan Peninsula, which is characterized by a terrestrial groundwater lens overlying marine groundwater intrusion with active submarine discharge through coastal springs. Terrestrial groundwater calcium (1-5 mmol kg-1) and alkalinity (3-8 mmol kg-1) are enriched over that predicted by equilibrium between recharging precipitation and calcite, which can be accounted for by groundwater organic matter respiration and subsequent dissolution of calcite, dolomite and gypsum. There is a close agreement between the observed terrestrial groundwater Sr/Ca, Mn/Ca, Ba/Ca and Ra/Ca and that predicted by equilibrium dissolution of calcite, thus the trace element content of terrestrial groundwater is largely determined by mineral dissolution. Subsequent mixing between terrestrial groundwater and the ocean within the actively discharging springs is characterized by conservative mixing of Sr, Mn, Ba and Ca, while U is variable and Ra displays a large enrichment (salinity: 1.9-34.9, Ba: 60-300 nmol kg-1, Sr: 15-110 μmol kg-1, U: 0.3-35 nmol kg-1, Mn: 0.3-200 nmol kg-1, Ca: 4.3-12.9 mmol kg-1, 226Ra: 18-2140 dpm 100 L-1). The deep groundwater sampled through cenotes, local dissolution features, is typified by elevated Ba, Sr, Ca, Mn and Ra and the absence of U within marine groundwater, due to enhanced dissolution

  2. Trace element and isotope geochemistry of geothermal fluids, East Rift Zone, Kilauea, Hawaii

    SciTech Connect

    West, H.B.; Delanoy, G.A.; Thomas, D.M. . Hawaii Inst. of Geophysics); Gerlach, D.C. ); Chen, B.; Takahashi, P.; Thomas, D.M. Evans and Associates, Redwood City, CA )

    1992-01-01

    A research program has been undertaken in an effort to better characterize the composition and the precipitation characteristic of the geothermal fluids produced by the HGP-A geothermal well located on the Kilauea East Rift Zone on the Island of Hawaii. The results of these studies have shown that the chemical composition of the fluids changed over the production life of the well and that the fluids produced were the result of mixing of at least two, and possibly three, source fluids. These source fluids were recognized as: a sea water composition modified by high temperature water-rock reactions; meteoric recharge; and a hydrothermal fluid that had been equilibrated with high temperature reservoir rocks and magmatic volatiles. Although the major alkali and halide elements show clearly increasing trends with time, only a few of the trace transition metals show a similar trend. The rare earth elements, were typically found at low concentrations and appeared to be highly variable with time. Studies of the precipitation characteristics of silica showed that amorphous silica deposition rates were highly sensitive to fluid pH and that increases in fluid pH above about 8.5 could flocculate more than 80% of the suspended colloidal silica in excess of its solubility. Addition of transition metal salts were also found to enhance the recovery fractions of silica from solution. The amorphous silica precipitate was also found to strongly scavenge the alkaline earth and transition metal ions naturally present in the brines; mild acid treatments were shown to be capable of removing substantial fractions of the scavenged metals from the silica flocs yielding a moderately pure gelatinous by-product. Further work on the silica precipitation process is recommended to improve our ability to control silica scaling from high temperature geothermal fluids or to recover a marketable silica by-product from these fluids prior to reinjection.

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

    PubMed

    Franus, Wojciech; Wiatros-Motyka, Małgorzata 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.

  4. 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.

  5. Distribution and geochemistry of selected trace elements in the Sacramento River near Keswick Reservoir

    USGS Publications Warehouse

    Antweiler, Ronald C.; Taylor, Howard E.; Alpers, Charles N.

    2012-01-01

    The effect of heavy metals from the Iron Mountain Mines (IMM) Superfund site on the upper Sacramento River is examined using data from water and bed sediment samples collected during 1996-97. Relative to surrounding waters, aluminum, cadmium, cobalt, copper, iron, lead, manganese, thallium, zinc and the rare-earth elements (REE) were all present in high concentrations in effluent from Spring Creek Reservoir (SCR), which enters into the Sacramento River in the Spring Creek Arm of Keswick Reservoir. SCR was constructed in part to regulate the flow of acidic, metal-rich waters draining the IMM Superfund site. Although virtually all of these metals exist in SCR in the dissolved form, upon entering Keswick Reservoir they at least partially converted via precipitation and/or adsorption to the particulate phase. In spite of this, few of the metals settled out; instead the vast majority was transported colloidally down the Sacramento River at least to Bend Bridge, 67 km from Keswick Dam. The geochemical influence of IMM on the upper Sacramento River was variable, chiefly dependent on the flow of Spring Creek. Although the average flow of the Sacramento River at Keswick Dam is 250 m3/s (cubic meters per second), even flows as low as 0.3 m3/s from Spring Creek were sufficient to account for more than 15% of the metals loading at Bend Bridge, and these proportions increased with increasing Spring Creek flow. The dissolved proportion of the total bioavailable load was dependent on the element but steadily decreased for all metals, from near 100% in Spring Creek to values (for some elements) of less than 1% at Bend Bridge; failure to account for the suspended sediment load in assessments of the effect of metals transport in the Sacramento River can result in estimates which are low by as much as a factor of 100.

  6. Distribution and geochemistry of selected trace elements in the Sacramento River near Keswick Reservoir

    USGS Publications Warehouse

    Antweiler, R.C.; Taylor, H.E.; Alpers, C.N.

    2012-01-01

    The effect of heavy metals from the Iron Mountain Mines (IMM) Superfund site on the upper Sacramento River is examined using data from water and bed sediment samples collected during 1996-97. Relative to surrounding waters, aluminum, cadmium, cobalt, copper, iron, lead, manganese, thallium, zinc and the rare-earth elements (REE) were all present in high concentrations in effluent from Spring Creek Reservoir (SCR), which enters into the Sacramento River in the Spring Creek Arm of Keswick Reservoir. SCR was constructed in part to regulate the flow of acidic, metal-rich waters draining the IMM Superfund site. Although virtually all of these metals exist in SCR in the dissolved form, upon entering Keswick Reservoir they at least partially converted via precipitation and/or adsorption to the particulate phase. In spite of this, few of the metals settled out; instead the vast majority was transported colloidally down the Sacramento River at least to Bend Bridge, 67. km from Keswick Dam.The geochemical influence of IMM on the upper Sacramento River was variable, chiefly dependent on the flow of Spring Creek. Although the average flow of the Sacramento River at Keswick Dam is 250m 3/s (cubic meters per second), even flows as low as 0.3m 3/s from Spring Creek were sufficient to account for more than 15% of the metals loading at Bend Bridge, and these proportions increased with increasing Spring Creek flow.The dissolved proportion of the total bioavailable load was dependent on the element but steadily decreased for all metals, from near 100% in Spring Creek to values (for some elements) of less than 1% at Bend Bridge; failure to account for the suspended sediment load in assessments of the effect of metals transport in the Sacramento River can result in estimates which are low by as much as a factor of 100. ?? 2012.

  7. Major and trace element geochemistry of Lake Bogoria and Lake Nakuru, Kenya, during extreme draught

    PubMed Central

    Jirsa, Franz; Gruber, Martin; Stojanovic, Anja; Omondi, Steve Odour; Mader, Dieter; Körner, Wilfried; Schagerl, Michael

    2013-01-01

    The physico-chemical properties of water samples from the two athalassic endorheic lakes Bogoria and Nakuru in Kenya were analysed. Surface water samples were taken between July 2008 and October 2009 in weekly intervals from each lake. The following parameters were determined: pH, salinity, electric conductivity, dissolved organic carbon (DOC), the major cations (FAAS and ICP-OES) and the major anions (IC), as well as certain trace elements (ICP-OES). Samples of superficial sediments were taken in October 2009 and examined using Instrumental Neutron Activation Analysis (INAA) for their major and trace element content including rare earth elements (REE). Both lakes are highly alkaline with a dominance of Na > K > Si > Ca in cations and HCO3 > CO3 > Cl > F > SO4 in anions. Both lakes also exhibited high concentrations of Mo, As and fluoride. Due to an extreme draught from March to October 2009, the water level of Lake Nakuru dropped significantly. This created drastic evapoconcentration, with the total salinity rising from about 20‰ up to 63‰. Most parameters (DOC, Na, K, Ca, F, Mo and As) increased with falling water levels. A clear change in the quality of DOC was observed, followed by an almost complete depletion of dissolved Fe from the water phase. In Lake Bogoria the evapoconcentration effects were less pronounced (total salinity changed from about 40‰ to 48‰). The distributions of REE in the superficial sediments of Lake Nakuru and Lake Bogoria are presented here for the first time. The results show a high abundance of the REE and a very distinct Eu depletion of Eu/Eu* = 0.33–0.45. PMID:25843965

  8. Contamination in the Rare-Earth Element Orthophosphate Reference Samples

    PubMed Central

    Donovan, John J.; Hanchar, John M.; Picolli, Phillip M.; Schrier, Marc D.; Boatner, Lynn A.; Jarosewich, Eugene

    2002-01-01

    Several of the fourteen rare-earth element (plus Sc and Y) orthophosphate standards grown at Oak Ridge National Laboratory in the 1980s and widely distributed by the Smithsonian Institution’s Department of Mineral Sciences, are significantly contaminated by Pb. The origin of this impurity is the Pb2P2O7 flux that is derived from the thermal decomposition of PbHPO4. The lead pyrophosphate flux is used to dissolve the oxide starting materials at elevated temperatures (≈1360 °C) prior to the crystal synthesis. Because these rare-earth element standards are extremely stable under the electron beam and considered homogenous, they have been of enormous value to electron probe micro-analysis (EPMA). The monoclinic, monazite structure, orthophosphates show a higher degree of Pb incorporation than the tetragonal xenotime structure, orthophosphates. This paper will attempt to describe and rationalize the extent of the Pb contamination in these otherwise excellent materials. PMID:27446762

  9. Trace element geochemistry and genesis of Precambrian sub-alkaline mafic dikes from the central Indian craton: evidence for mantle metasomatism

    NASA Astrophysics Data System (ADS)

    Srivastava, Rajesh K.; Singh, R. K.

    2004-07-01

    Precambrian mafic dikes transect the Archaean granite gneisses of the southern Bastar craton, Central India. On the basis of high-field strength elements, the Bastar mafic dike swarms were sub-divided into an earlier BD1 and a later BD2 system. The BD1 set comprises amphibolites, whereas the BD2 set consists of dolerites/metadolerites. On the basis of field relationships and available age data for enveloping granite rocks, the BD1 dikes are regarded as middle Archaean in age and BD2 dikes are Paleoproterozoic (˜1.8 Ga). The silica and total-alkalis contents of dikes of both swarms classified them mostly as sub-alkaline basalts. The BD1 dikes are low Ti+Fe and high-Mg olivine to quartz normative rocks, whereas the BD2 dikes are predominantly quartz normative with relatively high Ti+Fe and low-Mg contents. The high-field strength element concentrations are relatively higher in the BD2 dikes than in the BD1 dikes for comparable values of MgO and/or Cr. Judging from the geochemical data, these dikes probably were not contaminated by crustal components. The geochemistry and field observations clearly suggest a continental rift environment for the emplacement of both BD1 and BD2 dikes. Rare-earth element patterns and compatible-incompatible trace element modelling suggest that the two swarms were derived from distinctly different sub-alkaline basaltic magmas. The middle Archaean BD1 dikes were derived from ˜15-20% batch melting of a depleted lherzolite mantle source; in contrast, the Paleoproterozoic BD2 dikes were derived from ˜7-10% batch melting of a relatively enriched mantle source. A post Archaean increase in the thickness of metasomatized mantle lithosphere is the probable cause of mantle enrichment.

  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. Variations in trace element geochemistry in the Seine River Basin based on floodplain deposits and bed sediments

    USGS Publications Warehouse

    Horowitz, A.J.; Meybeck, Michel; Idlafkih, Z.; Biger, E.

    1999-01-01

    Between 1990 and 1995 a series of bed sediment, suspended sediment and fresh floodplain samples were collected within the Seine River Basin, in France, to evaluate variations in trace element geochemistry. Average background trace element levels for the basin were determined from the collection and subsequent analyses of bed sediment samples from small rural watersheds and from a prehistoric (5000 BP) site in Paris. Concentrations are relatively low, and similar to those observed for fine-grained bed sediments from unaffected areas in the United States and Canada. However, the concentrations are somewhat higher than the reference levels presently adopted by French water authorities for areas north of the Seine Basin, which have similar bedrock lithologies. Downstream trace element variations were monitored in 1994 and 1995 using fresh surficial floodplain samples that were collected either as dried deposits a few days after peak discharge, or immediately after peak discharge (under ??? 30 cm of water). Chemical comparisons between fresh floodplain deposits, and actual suspended sediments collected during flood events, indicate that, with some caveats, the former can be used as surrogates for the latter. The floodplain sediment chemical data indicate that within the Seine Basin, from the relatively unaffected headwaters through heavily affected urban streams, trace element concentrations vary by as much as three orders of magnitude. These trace element changes appear to be the result of both increases in population as well as concomitant increases in industrial activity. This article is a US government work and is in the public domain in the United States.

  12. 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.

  13. Trace element geochemistry of altered volcanic ash layers (tonsteins) in late Permian coal-bearing formations of eastern Yunnan and western Guizhou Provinces, China

    USGS Publications Warehouse

    Zhou, Y.; Bohor, B.F.; Ren, Y.

    2000-01-01

    Trace element compositions were determined (by instrumental neutron activation analysis; INAA) in 30 samples of synsedimentary volcanic ash-derived tonsteins and detrital claystones from coal seams within the late Permian coal-bearing formation of eastern Yunnan and western Guizhou Provinces, China. The characteristics of trace-element geochemistry in the tonsteins can be distinguished from those of detrital claystones because of the former's unique volcanic-ash origin. The detrital claystones are characterized by their relatively high content of V, Ti, Sc, Cr, Co and Ni, relatively low content of Th and U, Th/U ratio, and small negative Eu anomaly (Eu/Eu* 0.63-0.93). Overall, these trace element characteristics are consistent with a mafic source similar to the composition of basalt rocks in the erosional region on the western edge of the study area. In contrast, the tonsteins are low in V, Ti, Sc, Cr, Co and Ni contents and have a high Th/U ratio with a distinct negative Eu anomaly (Eu/Eu* normally in the range of 0.2-0.4), consistent with a silicic magmatic source. Within the group of tonsteins, those from the lower section (P2.1) of the coal-bearing formation are relatively high in Ti, Zr, Hf, Nb, Ta and rare earth elements (REE), as compared to those from the middle and upper sections (P2.2+3). In trace-element discrimination diagrams (scatter plots) of Hf-Ta, Ti-Ta, Ti-V, Hf-Sc, Lu-Hf and Lu-Th, tonsteins from the P2.1 horizon always fall in isolated distribution areas, separate from the tonsteins of the P2.2+3 horizon. These results suggest that the source materials of tonsteins from the two separate horizons were probably derived from volcanic ash falls of two distinctly different natures. Based on a comparison of the concentrations and assemblages of trace elements between various magmatic rocks, the source materials of tonsteins from P2.1 horizon were mostly composed of calc-alkalic, silica-poor volcanic ash (similar to rhyodacitic magma), whereas those

  14. Uncovering the global life cycles of the rare earth elements.

    PubMed

    Du, Xiaoyue; Graedel, T E

    2011-01-01

    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.

  15. 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.

  16. Petrology and trace element geochemistry of Tissint, the newest shergottite fall

    NASA Astrophysics Data System (ADS)

    Balta, J. Brian; Sanborn, Matthew E.; Udry, Arya; Wadhwa, Meenakshi; McSween, Harry Y.

    2015-01-01

    AbstractThe fall and recovery of the Tissint meteorite in 2011 created a rare opportunity to examine a Martian sample with a known, short residence time on <span class="hlt">Earth</span>. Tissint is an olivine-phyric shergottite that accumulated olivine antecrysts within a single magmatic system. Coarse olivine grains with nearly homogeneous cores of Mg# >80 suggest slow re-equilibration. Many macroscopic features of this sample resemble those of LAR 06319, including the olivine crystal size distribution and the presence of evolved oxide and olivine compositions. Unlike LAR 06319, however, no magmatic hydrous phases were found in the analyzed samples of Tissint. Minor and trace <span class="hlt">element</span> compositions indicate that the meteorite is the product of closed-system crystallization from a parent melt derived from a depleted source, with no obvious addition of a LREE-rich (crustal?) component prior to or during crystallization. The whole-rock REE pattern is similar to that of intermediate olivine-phyric shergottite EETA 79001 lithology A, and could also be approximated by a more olivine-rich version of depleted basaltic shergottite QUE 94201. Magmatic oxygen fugacities are at the low end of the shergottite range, with log fO2 of QFM-3.5 to -4.0 estimated based on early-crystallized minerals and QFM-2.4 estimated based on the Eu in pyroxene oxybarometer. These values are similarly comparable to other depleted shergottites, including SaU 005 and QUE 94201. Tissint occupies a previously unsampled niche in shergottite chemistry: containing olivines with Mg# >80, resembling the enriched olivine-phyric shergottite LAR 06319 in its crystallization path, and comparable to intermediate olivine-phyric shergottite EETA 79001A, depleted olivine-phyric shergottite DaG 476, and depleted basaltic shergottite QUE 94201 in its trace <span class="hlt">element</span> abundances and oxygen fugacity. The apparent absence of evidence for terrestrial alteration in Tissint</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V23A2803M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V23A2803M"><span><span class="hlt">Geochemistry</span> of banded iron formation (BIF) host rocks, Yishui county, North China : major <span class="hlt">element</span>, REE and other trace <span class="hlt">element</span> analyses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moon, I.; Lee, I.; Yang, X.</p> <p>2013-12-01</p> <p>Banded iron formation (BIF) in Yishui area, Western Shangdong Province in North China was formed from late Archean to early Paleoproterizoic (2.6Ga-2.5Ga). Amphibolite, metasediment (schist, gneiss) and migmatitic granite consist of host rocks of the BIF in North China. To find characteristics of BIF host rocks, major <span class="hlt">element</span>, rare <span class="hlt">earth</span> <span class="hlt">element</span> and trace <span class="hlt">element</span> analyses of whole rocks were conducted. Major <span class="hlt">elements</span> are analyzed using X-ray Fluorescene Spectrometer (XRF) and REE and trace <span class="hlt">elements</span> are analyzed by Inductively Coupled Plazma Mass Spectrometer (ICP-MS). Amphibolites show large negative Eu anomalies ([Eu]/[Eu*]=0.91~0.99) and ranges of REE are ∑REE=305~380 ppm. LREE/HREE ratios are (La/Lu)cn=21.07~26.12. SiO2 contents are 35.1~44.2 wt% and some samples have high Loss On Ignition values ([LOI]=8.35-10.06 wt%) compared to other amphibolites. LOI value is related to water and volatile contents in the rocks and it reflects amphibolite got high degree of alteration. The Fe and Mg mobility effects are shown by Fe2O3/MgO ratios which are 4.7~5.7. The Mg# varies from 25.6 to 29.3. Migmatitic granites have various range of ∑REE=21~241 ppm. They show both Eu negative anomalies ([Eu]/[Eu*]=0.53~0.71) and positive Eu anomalies ([Eu]/[Eu*]=1.95). Migmatitic granites have high SiO2 contents (68.8~72.2 wt%) and Al2O3 (13.4~14.2 wt%) contents. They have relatively low TiO2 (<0.5 wt%), MgO ( <0.6 wt%) and P2O5 (<0.2 wt%) contents. Gneiss samples were collected either from core or from mine pit. Core samples have negative Eu anomalies ([Eu]/[Eu*]=0.27~0.62) and show enriched LREE than HREE ((La/Lu)cn=45.60~62.32). Mine pit samples have positive Eu anomalies ([Eu]/[Eu*]=1.64~2.87) and almost flatten pattern except Eu anomalies ((La/Lu)cn=2.19~2.37). Core samples have higher Al2O3, TiO2, Na2O and K2O contents than mine pit samples. But remarkably mine pit samples have high contents of Fe2O3 (>40.4 wt%). Schists are divided into two types following REE patterns. Some</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021197','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021197"><span>Trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of metabasaltic rocks from the Yukon-Tanana Upland and implications for the origin of tectonic assemblages in east-central Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dusel-Bacon, C.; Cooper, K.M.</p> <p>1999-01-01</p> <p>We present major- and trace- <span class="hlt">element</span> geochemical data for 27 amphibolites and six greenstones from three structural packages in the Yukon-Tanana Upland of east-central Alaska: the Lake George assemblage (LG) of Devono-Mississippian augen gneiss, quartz-mica schist, quartzite, and amphibolite; the Taylor Mountain assemblage (TM) of mafic schist and gneiss, marble, quartzite, and metachert; and the Seventymile terrane of greenstone, serpentinized peridotite, and Mississippian to Late Triassic metasedimentary rocks. Most LG amphibolites have relatively high Nb, TiO2, Zr, and light rare <span class="hlt">earth</span> <span class="hlt">element</span> contents, indicative of an alkalic to tholeiitic, within-plate basalt origin. The within-plate affinities of the LG amphibolites suggest that their basaltic parent magmas developed in an extensional setting and support a correlation of these metamorphosed continental-margin rocks with less metamorphosed counterparts across the Tintina fault in the Selwyn Basin of the Canadian Cordillera. TM amphibolites have a tholeiitic or calc-alkalic composition, low normalized abundances of Nb and Ta relative to Th and La, and Ti/V values of <20, all indicative of a volcanic-arc origin. Limited results from Seventymile greenstones indicate a tholeiitic or calc-alkalic composition and intermediate to high Ti/V values (27-48), consistent with either a within-plate or an ocean-floor basalt origin. Y-La-Nb proportions in both TM and Seventymile metabasalts indicate the proximity of the arc and marginal basin to continental crust. The arc <span class="hlt">geochemistry</span> of TM amphibolites is consistent with a model in which the TM assemblage includes arc rocks generated above a west-dipping subduction zone outboard of the North American continental margin in mid-Paleozoic through Triassic time. The ocean-floor or within-plate basalt <span class="hlt">geochemistry</span> of the Seventymile greenstones supports the correlation of the Seventymile terrane with the Slide Mountain terrane in Canada and the hypothesis that these oceanic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUSM.V32A..03M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUSM.V32A..03M"><span>Insights Into the Early Volatile History of the <span class="hlt">Earth</span> From the <span class="hlt">Geochemistry</span> of Iodine and Xenon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Musselwhite, D.; Drake, M.</p> <p>2006-05-01</p> <p>Evidence that liquid water was stable on the <span class="hlt">Earth</span> before 4.4 by ago comes from studies of very old zircons. This evidence seems at odds with the giant impact model of the Moon's formation, which should have resulted in melting of a large portion of the <span class="hlt">Earth</span>'s interior and the formation of a deep magma ocean. The stabilization of a primitive crust, and the attainment of surface temperatures allowing liquid water stability would have to have occurred within about 100 my of the onset of solar nebula condensation. Xe129, produced by the decay of now extinct I129 (t1/2 = 17 my), provides a tracer for volatile processes in the earliest history of the <span class="hlt">Earth</span>. Catastrophic outgassing of the mantle as proposed to explain the Xe129/Xe132 ratios of MORBs (1.014) and the atmosphere (0.985) could have happened in the context of a post-giant-impact magma ocean only if it occurred on a timescale of 100 my or less. To assess the effects of outgassing of an early magma ocean on the I/Xe systematics of the <span class="hlt">Earth</span>'s mantle, we consider a simple two-reservoir (MORB-source mantle and atmosphere) model with partial melting of the mantle occurring in equilibrium with residual minerals followed by eruption and degassing. Experimentally determined I and Xe mineral/melt partition coefficients and silicate-melt solubility values for I and Xe are employed in mass balance calculations based on this two-reservoir model. The amount of I/Xe enrichment in the MORB-source mantle and the extent of melting and outgassing needed depend on the timing of outgassing. If it was completed by 50 my following solar nebula condensation, then the MORB-source mantle needs to have been at least 50% molten and 90% outgassed. If it was completed by 100 my, then the mantle must have been at least 95% molten and 99% outgassed. So, the longer the timescale of magma ocean outgassing, the more extensively melted it has to be. This result accentuates the necessity for a quick cooling of the magma ocean and the early</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070036261','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070036261"><span>The <span class="hlt">Earth</span> Based Ground Stations <span class="hlt">Element</span> of the Lunar Program</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gal-Edd, Jonathan; Fatig, Curtis; Schier, James; Lee, Charles</p> <p>2007-01-01</p> <p>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 <span class="hlt">elements</span> 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 <span class="hlt">Earth</span> view, <span class="hlt">earth</span>-based ground stations deployed at geographical locations 120 degrees apart. This paper will focus on the <span class="hlt">Earth</span> ground stations of the lunar architecture. Two types of ground station networks are discussed. One provides Direct to <span class="hlt">Earth</span> (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.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816699H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816699H"><span>Germanium and Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> accumulation in woody bioenergy crops</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hentschel, Werner</p> <p>2016-04-01</p> <p>Germanium and REEs are strategic <span class="hlt">elements</span> that are used for high tech devices and engineered systems, however these <span class="hlt">elements</span> are hardly concentrated into mineable ore deposits. Since these <span class="hlt">elements</span> occur widely dispersed in the <span class="hlt">earth</span> crust with concentrations of several mgṡkg-1 (Ge 1.6 mgṡkg-1, Nd 25 mgṡkg-1) a new possibility to gain these <span class="hlt">elements</span> could be phytomining, a technique that uses plants to extract <span class="hlt">elements</span> from soils via their roots. Since knowledge about accumulating plant species is quite limited we conducted research on the concentrations of strategic <span class="hlt">elements</span> in wood and leaves of fast growing tree species (Salix spec., Populus spec., Betula pendula, Alnus glutinosa, Fraxinus excelsior, Acer pseudoplatanus). In total 35 study sites were selected in the mining affected area around Freiberg (Saxony, Germany), differing in their species composition and degree of contamination with toxic trace metals (Pb, As, Cd). On each site plant tissues (wood and leaves, respectively) of different species were sampled. In addition soil samples were taken from a soil depth of 0 - 30 cm and 30 - 60 cm. The aim of our work was to investigate correlations between the concentrations of the target <span class="hlt">elements</span> in plant tissues and soil characteristics like pH, texture, nutrients and concentrations in six operationally defined soil fractions (mobile, acid soluble, oxidizable, amorphic oxides, crystalline oxides, residual or siliceous). Concentrations of <span class="hlt">elements</span> in soil extracts and plant tissues were measured with ICP-MS. The <span class="hlt">element</span> Nd was selected as representative for the group of REEs, since this <span class="hlt">element</span> showed a high correlation with the concentrations of the other REE We found that the concentration of Nd in the leaves (0.31 mgṡkg-1Nd) were several times higher than in herbaceous species (0.05 mgṡkg-1 Nd). The concentration of Ge in leaves were ten times lower than that of Nd whereas in herbaceous species Nd and Ge were in equal magnitude. Within the tree</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24324274','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24324274"><span><span class="hlt">Elemental</span> <span class="hlt">geochemistry</span> of sedimentary rocks at Yellowknife Bay, Gale crater, Mars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McLennan, S M; Anderson, R B; Bell, J F; Bridges, J C; Calef, F; Campbell, J L; Clark, B C; Clegg, S; Conrad, P; Cousin, A; Des Marais, D J; Dromart, G; Dyar, M D; Edgar, L A; Ehlmann, B L; Fabre, C; Forni, O; Gasnault, O; Gellert, R; Gordon, S; Grant, J A; Grotzinger, J P; Gupta, S; Herkenhoff, K E; Hurowitz, J A; King, P L; Le Mouélic, S; Leshin, L A; Léveillé, R; Lewis, K W; Mangold, N; Maurice, S; Ming, D W; Morris, R V; Nachon, M; Newsom, H E; Ollila, A M; Perrett, G M; Rice, M S; Schmidt, M E; Schwenzer, S P; Stack, K; Stolper, E M; Sumner, D Y; Treiman, A H; VanBommel, S; Vaniman, D T; Vasavada, A; Wiens, R C; Yingst, R A</p> <p>2014-01-24</p> <p>Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The <span class="hlt">geochemistry</span> of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5216629','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5216629"><span>Rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns in biotite, muscovite and tourmaline minerals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Laul, J.C.; Lepel, E.A.</p> <p>1986-04-21</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910053953&hterms=apatites&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dapatites','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910053953&hterms=apatites&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dapatites"><span>Compositional and phase relations among rare <span class="hlt">earth</span> <span class="hlt">element</span> minerals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burt, D. M.</p> <p>1989-01-01</p> <p>A review is presented that mainly treats minerals in which the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023771','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023771"><span>Standard reference water samples for rare <span class="hlt">earth</span> <span class="hlt">element</span> determinations</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Verplanck, P.L.; Antweiler, R.C.; Nordstrom, D.K.; Taylor, H.E.</p> <p>2001-01-01</p> <p>Standard reference water samples (SRWS) were collected from two mine sites, one near Ophir, CO, USA and the other near Redding, CA, USA. The samples were filtered, preserved, and analyzed for rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) by inductively coupled plasma-mass spectrometry (ICP-MS). These two samples were acid mine waters with elevated concentrations of REEs (0.45-161 ??g/1). Seventeen international laboratories participated in a 'round-robin' chemical analysis program, which made it possible to evaluate the data by robust statistical procedures that are insensitive to outliers. The resulting most probable values are reported. Ten to 15 of the participants also reported values for Ba, Y, and Sc. Field parameters, major ion, and other trace <span class="hlt">element</span> concentrations, not subject to statistical evaluation, are provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25848014','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25848014"><span>Mimicking the magnetic properties of rare <span class="hlt">earth</span> <span class="hlt">elements</span> using superatoms.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A W</p> <p>2015-04-21</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">earth</span> mimicry. Extension of the superatom concept into the rare <span class="hlt">earth</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22357200','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22357200"><span>Accumulation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> by siderophore-forming Arthrobacter luteolus isolated from rare <span class="hlt">earth</span> environment of Chavara, India.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Emmanuel, E S Challaraj; Ananthi, T; Anandkumar, B; Maruthamuthu, S</p> <p>2012-03-01</p> <p>In this study, Arthrobacter luteolus, isolated from rare <span class="hlt">earth</span> environment of Chavara (Quilon district, Kerala, India), were found to produce catechol-type siderophores. The bacterial strain accumulated rare <span class="hlt">earth</span> <span class="hlt">elements</span> such as samarium and scandium. The siderophores may play a role in the accumulation of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Catecholate siderophore and low-molecular-weight organic acids were found to be present in experiments with Arthrobacter luteolus. The influence of siderophore on the accumulation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> by bacteria has been extensively discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24489809','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24489809"><span>Trace <span class="hlt">elemental</span> imaging of rare <span class="hlt">earth</span> <span class="hlt">elements</span> discriminates tissues at microscale in flat fossils.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B; Cohen, Serge X; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc</p> <p>2014-01-01</p> <p>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 <span class="hlt">elemental</span> distributions greatly improved the discrimination of skeletal <span class="hlt">elements</span> material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline <span class="hlt">earth</span> <span class="hlt">elements</span> and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Local quantification of rare <span class="hlt">earths</span> may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3906100','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3906100"><span>Trace <span class="hlt">Elemental</span> Imaging of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Discriminates Tissues at Microscale in Flat Fossils</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B.; Cohen, Serge X.; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc</p> <p>2014-01-01</p> <p>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 <span class="hlt">elemental</span> distributions greatly improved the discrimination of skeletal <span class="hlt">elements</span> material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline <span class="hlt">earth</span> <span class="hlt">elements</span> and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Local quantification of rare <span class="hlt">earths</span> may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies. PMID:24489809</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B21C0451J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B21C0451J"><span>Bacterial Cell Surface Adsorption of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiao, Y.; Park, D.; Reed, D.; Fujita, Y.; Yung, M.; Anderko, A.; Eslamimanesh, A.</p> <p>2015-12-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) play a critical role in many emerging clean energy technologies, including high-power magnets, wind turbines, solar panels, hybrid/electric vehicle batteries and lamp phosphors. In order to sustain demand for such technologies given current domestic REE shortages, there is a need to develop new approaches for ore processing/refining and recycling of REE-containing materials. To this end, we have developed a microbially-mediated bioadsorption strategy with application towards enrichment of REE from complex mixtures. Specifically, the bacterium Caulobacter crescentus was genetically engineered to display lanthanide binding tags (LBTs), short peptides that possess high affinity and specificity for rare <span class="hlt">earth</span> <span class="hlt">elements</span>, on its cell surface S-layer protein. Under optimal conditions, LBT-displayed cells adsorbed greater than 5-fold more REE than control cells lacking LBTs. Competition binding experiments with a selection of REEs demonstrated that our engineered cells could facilitate separation of light- from heavy- REE. Importantly, binding of REE onto our engineered strains was much more favorable compared to non-REE metals. Finally, REE bound to the cell surface could be stripped off using citrate, providing an effective and non-toxic REE recovery method. Together, this data highlights the potential of our approach for selective REE enrichment from REE containing mixtures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850024768&hterms=earth+history&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dearth%2Bhistory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850024768&hterms=earth+history&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dearth%2Bhistory"><span>A review of noble gas <span class="hlt">geochemistry</span> in relation to early <span class="hlt">Earth</span> history</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kurz, M. D.</p> <p>1985-01-01</p> <p>One of the most fundamental noble gas constraints on early <span class="hlt">Earth</span> history is derived from isotopic differences in (129)Xe/(130)Xe between various terrestrial materials. The short half life (17 m.y.) of extinct (129I, parent of (129)Xe, means that these differences must have been produced within the first 100 m.y. after terrestrial accretion. The identification of large anomalies in (129)Xe/(130)Xe in mid ocean ridge basalts (MORB), with respect to atmospheric xenon, suggests that the atmosphere and upper mantle have remained separate since that time. This alone is a very strong argument for early catastrophic degassing, which would be consistent with an early fractionation resulting in core formation. However, noble gas isotopic systematics of oceanic basalts show that the mantle cannot necessarily be regarded as a homogeneous system, since there are significant variations in (3)He/(4)He, (40)Ar/(36)Ar, and (129)Xe/(130)Xe. Therefore, the early degassing cannot be considered to have acted on the whole mantle. The specific mechanisms of degassing, in particular the thickness and growth of the early crust, is an important variable in understanding present day noble gas inventories. Another constraint can be obtained from rocks that are thought to be derived from near the lithosphere asthenosphere boundary: ultramafic xenoliths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890011981','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890011981"><span>Trace <span class="hlt">element</span> and isotope <span class="hlt">geochemistry</span> of Cretaceous-Tertiary boundary sediments: identification of extra-terrestrial and volcanic components</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Margolis, S. V.; Doehne, E. F.</p> <p>1988-01-01</p> <p>Trace <span class="hlt">element</span> and stable isotope analyses were performed on a series of sediment samples crossing the Cretaceous-Tertiary (K-T) boundary from critical sections at Aumaya and Sopelano, Spain. The aim is to possibly distinguish extraterrestrial vs. volcanic or authigenic concentration of platinum group and other <span class="hlt">elements</span> in K-T boundary transitional sediments. These sediments also have been shown to contain evidence for step-wise extinction of several groups of marine invertebrates, associated with negative oxygen and carbon isotope excursions occurring during the last million years of the Cretaceous. These isotope excursions have been interpreted to indicate major changes in ocean thermal regime, circulation, and ecosystems that may be related to multiple events during latest Cretaceous time. Results to date on the petrographic and geochemical analyses of the Late Cretaceous and Early Paleocene sediments indicate that diagenesis has obviously affected the trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and stable isotope compositions at Zumaya. Mineralogical and geochemical analysis of K-T boundary sediments at Zumaya suggest that a substantial fraction of anomalous trace <span class="hlt">elements</span> in the boundary marl are present in specific mineral phases. Platinum and nickel grains perhaps represent the first direct evidence of siderophile-rich minerals at the boundary. The presence of spinels and Ni-rich particles as inclusions in aluminosilicate spherules from Zumaya suggests an original, non-diagenetic origin for the spherules. Similar spherules from southern Spain (Caravaca), show a strong marine authigenic overprint. This research represents a new approach in trying to directly identify the sedimentary mineral components that are responsible for the trace <span class="hlt">element</span> concentrations associated with the K-T boundary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP51D..01Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP51D..01Z"><span>Diagenetic uptake of rare <span class="hlt">earth</span> <span class="hlt">elements</span> by conodont apatite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, L.; Algeo, T. J.; Cao, L.; Zhao, L.; Chen, Z. Q.; Li, Z.</p> <p>2015-12-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) composition of bioapatite has long been used as a proxy for ancient seawater chemistry and paleomarine environmental reconstruction, based on the assumption of preservation of a hydrogenous (seawater-derived) REE signal. Recent work, however, has begun to question the provenance of REEs in conodonts, emphasizing the importance of REEs released by the lithogenous fraction of the sediment and subsequently adsorbed onto conodont apatite in the burial environment. Here, we investigate patterns of REE and trace-<span class="hlt">element</span> abundance in conodonts and their host sediments from the Early to Late Ordovician Huanghuachang and Chenjiahe sections of Hubei Province, South China. Several lines of evidence indicate that REEs in the conodont samples were acquired mainly from clay minerals in the host sediment during burial diagenesis: (1) REEs in conodonts show a strong positive correlation to Th and other lithogenic <span class="hlt">elements</span>; (2) conodonts and whole-rock samples show general patterns of REE and trace-<span class="hlt">element</span> enrichment that are highly similar to each other and bear no resemblance to seawater <span class="hlt">elemental</span> concentrations; (3) similar patterns are observed in Triassic conodonts and whole-rock samples; and (4) Y/Ho ratios in conodonts are mostly <40 (mean ~33), values that are consistent with derivation of >90% of REEs from lithogenous sources. Conodonts show pronounced middle rare <span class="hlt">earth</span> <span class="hlt">element</span> (MREE) enrichment, a pattern that is unambiguously of diagenetic origin owing to its association with lower Y/Ho ratios. With increasing MREE enrichment of conodont samples, U concentrations and LaN/YbN ratios shift from high to low, and Mn concentrations from low to high. These patterns suggest that conodont diagenesis was initiated at shallow burial depths under suboxic conditions (i.e., in the zone of Mn(IV) and Fe(III) reduction) but continued at greater burial depths, with most acquisition of secondary REEs at later diagenetic stages. Our findings indicate that (1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.442..194O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.442..194O"><span><span class="hlt">Geochemistry</span> and Nd isotopic characteristics of <span class="hlt">Earth</span>'s Hadean mantle and primitive crust</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>O'Neil, J.; Rizo, H.; Boyet, M.; Carlson, R. W.; Rosing, M. T.</p> <p>2016-05-01</p> <p>The Isua supracrustal belt (ISB) and the Nuvvuagittuq greenstone belt (NGB) are among the oldest suites of mafic volcanic rocks preserved on <span class="hlt">Earth</span> and are the best candidates for representing its early crust. Despite the possible 500 Ma age difference between the belts, these mantle-derived rocks show compositional similarities, with features resembling rocks formed in subduction initiation environments. With the addition of new 142Nd data for the Garbenschiefer unit of the ISB reported here, high precision 142Nd data are now available for all the mafic lithologies from both belts. Mantle-derived rocks from both the ISB and NGB belts exhibit a range of 142Nd/144Nd ratios. The datasets for the two belts, however, are significantly different, suggesting a different origin for their 142Nd anomalies. Nearly all ISB samples have excesses in 142Nd, including the newly analyzed Garbenschiefer boninitic amphibolites (mean of + 12 ppm). Excesses in 142Nd/144Nd compared to the Nd standard for all the ISB rocks range between +8 and + 20 ppm, with a near Gaussian distribution around + 12 ppm. This distribution could simply reflect the analytical error (±5 ppm) around a single 142Nd/144Nd ratio indicating that the samples formed after the extinction of 146Sm from a source with a nearly uniform 142Nd/144Nd ratio. In contrast, the NGB shows a range of 142Nd/144Nd ratios from +8 to - 18 ppm relative to the modern Nd standard and displays a flat distribution of 142Nd/144Nd ratios. The ISB samples show no significant correlation between their 142Nd/144Nd and Sm/Nd ratios, consistent with their formation in the Eoarchean via melting of a Hadean depleted mantle. In contrast, all NGB samples display a 142Nd/144Nd vs. Sm/Nd correlation, consistent with their crystallization in the Hadean. The mantle sources for both the ISB and NGB mantle-derived rocks have a similar 142Nd/144Nd ratio at the possible age of formation of the NGB (∼4.3 Ga) suggesting the derivation of ISB and NGB rocks</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24662205','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24662205"><span>Urban soil <span class="hlt">geochemistry</span> in Athens, Greece: The importance of local geology in controlling the distribution of potentially harmful trace <span class="hlt">elements</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Argyraki, Ariadne; Kelepertzis, Efstratios</p> <p>2014-06-01</p> <p>Understanding urban soil <span class="hlt">geochemistry</span> is a challenging task because of the complicated layering of the urban landscape and the profound impact of large cities on the chemical dispersion of harmful trace <span class="hlt">elements</span>. A systematic geochemical soil survey was performed across Greater Athens and Piraeus, Greece. Surface soil samples (0-10cm) were collected from 238 sampling sites on a regular 1×1km grid and were digested by a HNO3-HCl-HClO4-HF mixture. A combination of multivariate statistics and Geographical Information System approaches was applied for discriminating natural from anthropogenic sources using 4 major <span class="hlt">elements</span>, 9 trace metals, and 2 metalloids. Based on these analyses the lack of heavy industry in Athens was demonstrated by the influence of geology on the local soil chemistry with this accounting for 49% of the variability in the major <span class="hlt">elements</span>, as well as Cr, Ni, Co, and possibly As (median values of 102, 141, 16 and 24mg kg(-1) respectively). The contribution to soil chemistry of classical urban contaminants including Pb, Cu, Zn, Sn, Sb, and Cd (medians of 45, 39, 98, 3.6, 1.7 and 0.3mg kg(-1) respectively) was also observed; significant correlations were identified between concentrations and urbanization indicators, including vehicular traffic, urban land use, population density, and timing of urbanization. Analysis of soil heterogeneity and spatial variability of soil composition in the Greater Athens and Piraeus area provided a representation of the extent of anthropogenic modifications on natural <span class="hlt">element</span> loadings. The concentrations of Ni, Cr, and As were relatively high compared to those in other cities around the world, and further investigation should characterize and evaluate their geochemical reactivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850007334&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2527%2527rare%2Bearths%2527%2527','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850007334&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2527%2527rare%2Bearths%2527%2527"><span>The chemistry of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the solar nebula</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Larimer, J. W.; Bartholomay, H. A.; Fegley, B.</p> <p>1984-01-01</p> <p>The high concentration of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in primitive CaS suggests that the REE along with the other normally lithophile <span class="hlt">elements</span> 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 <span class="hlt">elemental</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005E%26PSL.239...79H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005E%26PSL.239...79H"><span>Revisiting the rare <span class="hlt">earth</span> <span class="hlt">elements</span> in foraminiferal tests [rapid communication</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haley, Brian A.; Klinkhammer, Gary P.; Mix, Alan C.</p> <p>2005-10-01</p> <p>Are the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in foraminifera a valuable proxy for use in paleoceanographic and climate change studies? In order to investigate this, we attempted a comprehensive study of REEs in planktonic and benthic foraminifera. Several different cleaning protocols were tested. Although the hydroxylamine used to clean all foraminifera in this study removes an unidentified source of REE contamination, it seems to remobilize metal oxides that are otherwise unaffected in flow-through dissolution. The calculated REE distribution coefficients, KD(REE)s, are between 100 and 500 for both planktonic and benthic foraminifera. These KDs are high compared to other <span class="hlt">elements</span> in biogenic calcite but can be explained through a general model of <span class="hlt">element</span> incorporation during foraminiferal calcification. From data taken from eight core tops in the southeast Pacific, we conclude that the REEs in planktonic foraminifera are, indeed, useful as a proxy for upper ocean water mass and mixed layer biogenic productivity. Alternatively, the REEs in benthic foraminifera are useful as a proxy for carbon flux to the sea floor. These proxies should be robust down core unless the sediments have undergone anoxic diagenesis, which stabilizes Fe carbonate thus overprinting the primary REE signature. However, it is clear from REE distributions in foraminiferal tests if anoxic conditions have occurred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17834611','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17834611"><span>Lunar anorthosites: rare-<span class="hlt">Earth</span> and other <span class="hlt">elemental</span> abundances.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wakita, H; Schmitt, R A</p> <p>1970-11-27</p> <p><span class="hlt">Elemental</span> abundances of major (Ti, Al, Fe, and Ca), minor (Na, Mn, and Cr), and trace <span class="hlt">elements</span> [14 rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE), Y, In, Cd, Rb, Cs, Ba, Co, and Sc] in lunar anorthosites separated from Apollo 11 sample 10085 coarse fines have been determined by means of instrumental and radiochemical neutron activation analysis. The REE distribution pattern of lunar anorthosites, relative to ordinary chondrites, has a positive Eu anomaly. On the assumption that (i) the lunar composition is similar to that of ordinary chondritic meteorites low in total Fe ( approximately 13 percent); (ii) lunar anorthosites are derived from highland cratering events and are representative of the highlands; and (iii) the moon differentiated into olivine, hypersthene, and basaltic and anorthositic phases, and plagioclase crysstallization began after approximately 93 percent solidification, then mass balance calculations yield approximately 30-kilometer and approximately 10-kilometer thicknesses for the lunar highlands for the melting and chemical differentiation of the entire moon and of the upper 200 kilometers, respectively. Corresponding thicknesses of the basaltic basement rocks were approximately 5 kilometers and approximately 2 kilometers, respectively. Alternatively, if the anorthosites of this study are representative of the highlands and the onset of plagioclase crystallization occurred after approximately 50 percent solidification of the initially melted moon, calculations with REE and Ba partition coefficients suggest that the REE and Ba abundances in the primeval moon were similar to those observed in basaltic achondrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1811466A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811466A"><span>Mineralogy, <span class="hlt">Geochemistry</span> and Mass Changes at the Mombi Bauxite Deposit, (SW Iran): Using Geochemical Characteristics of the Immobile <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ahmadnejad, Farhad; Vahabzadeh, Bahman; Zamanian, Hassan; Sameti, Mona; Asadi Haroni, Hooshang</p> <p>2016-04-01</p> <p>The Mombi bauxite deposit is located 160Km northwest of Dehdasht in the Zagros fold belt of Iran. The bauxite horizons are mineralogically homogeneous, and contains high amount of boehmite, diaspore, hematite, kaolinite, and anatase. Total geochemical analysis of the bauxite shows that Al2O3, SiO2, Fe2O3 and TiO2 are the main components. The immobile <span class="hlt">elements</span> of Al, Ti, Nb, Zr, Hf, Cr, Ta, Y and Th are enriched while Rb, Ba, K, Sr, and P are depleted during bauxitization process. Chondrite-normalized REE pattern in the bauxite ore indicates REE enrichment (ΣREE=162.8-755.28ppm, ave. ~ 399.36 ppm) relative to the argillized limestone (ΣREE=76.26-84.03 ppm, ave. ~ 80.145 ppm). These patterns also reflect enrichment in LREE relative to HREE. Both positive and negative Ce anomalies (0.48-2.0) are observed in the Mombi bauxite horizons. These anomalies are related to the oxidation state of Ce (from Ce3+ to Ce4+), ionic potential, and complication of Ce4+ with carbonate compounds in the studied horizon. The present study uses the <span class="hlt">geochemistry</span> of immobile <span class="hlt">elements</span> to calculate the mass changes occurred during weathering and bauxitization. The results reveal that <span class="hlt">elements</span> such as Si, Fe, Mg, P, K, Ba, Sr and Zn are depleted, while Al, Zr, V, Cr, Ni, Ga, Y and LREEs indicate positive mass changes during the weathering and bauxitization. In addition, Nb, Hf, Ta, Bi, Rb, Cs, U and HRRE exhibit little changes, suggesting relatively immobile features. Inter-<span class="hlt">elemental</span> relationship analyses of the bauxite by using R-mode factor analysis method suggest that the <span class="hlt">elemental</span> behaviors of trace <span class="hlt">elements</span> and REEs during bauxite mineralization are mainly controlled by the mineral compositions and chemical properties of the <span class="hlt">elements</span>. R-mode factor analysis reveals a number of key findings: (i) some of the low solubility <span class="hlt">elements</span> were concentrated in detrital zircon (Zr), in anatase (Ti), and possibly in boehmite and hematite during the later stages of bauxitisation; (ii) Fe was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SedG..346...35N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SedG..346...35N"><span><span class="hlt">Elemental</span> <span class="hlt">geochemistry</span> and strontium-isotope stratigraphy of Cenomanian to Santonian neritic carbonates in the Zagros Basin, Iran</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Navidtalab, Amin; Rahimpour-Bonab, Hossain; Huck, Stefan; Heimhofer, Ulrich</p> <p>2016-12-01</p> <p>A Neo-Tethyan upper Cenomanian-Santonian neritic carbonate ramp succession (Sarvak and Ilam formations), drilled in the Zagros Basin in southwest Iran, was investigated via detailed sedimentology, microfacies analysis, <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> and Sr-isotope stratigraphy (SIS). The succession contains two exposure surfaces, which are known as the CT-ES and mT-ES (Cenomanian-Turonian and middle Turonian, respectively), and associated prominent negative carbon-isotope excursions that represent important regional stratigraphic marker horizons. Precise knowledge about the onset of platform exposure and the duration of the exposure-related hiatus, however, is currently lacking due to a rather low-resolved shallow-water biostratigraphic framework and a bulk carbonate carbon-isotope pattern that clearly differs from global Late Cretaceous reference curves. Therefore, the existing bio-chemostratigraphic framework was complemented by bulk carbonate strontium-isotope stratigraphy (SIS). As bulk carbonate material is in particular prone to diagenetic alteration, a careful selection of least altered samples has been carried out by means of <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> and petrography. In contrast to what could be expected, the meteoric alteration of limestones beneath both exposure surfaces is not clearly expressed by increasing iron and manganese and coeval decreasing strontium contents. On the contrary, the impact of meteoric diagenesis is well illustrated via pronounced increases in Rb concentrations and concomitant prominent positive shifts to radiogenic strontium-isotope values, an observation that clearly reflects the decay of continentally derived 87Rb into 87Sr. Rubidium corrected strontium-isotope values place the CT-ES around the Cenomanian-Turonian boundary and point to an exposure duration of less than 0.4 Myr. This rather short-term CT-ES related hiatus is supported by petrographic evidence, which indicates a youth karstification stage of strata beneath the CT</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840011975','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840011975"><span>The <span class="hlt">elements</span> of the <span class="hlt">Earth</span>'s magnetism and their secular changes between 1550 and 1915</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fritsche, H.</p> <p>1983-01-01</p> <p>The results of an investigation about the magnetic agents outside the <span class="hlt">Earth</span>'s surface as well as the <span class="hlt">Earth</span>'s magnetic <span class="hlt">elements</span> for the epochs 1550, 1900, 1915 are presented. The secular changes of the <span class="hlt">Earth</span>'s magnetic <span class="hlt">elements</span> during the time interval 1550 - 1900 are also included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27979199','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27979199"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in parasol mushroom Macrolepiota procera.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Falandysz, Jerzy; Sapkota, Atindra; Mędyk, Małgorzata; Feng, Xinbin</p> <p>2017-04-15</p> <p>This study aimed to investigate occurrence and distribution of 16 rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in edible saprobic mushroom Macrolepiota procera, and to estimate possible intake and risk to human consumer. Mushrooms samples were collected from sixteen geographically diverse sites in the northern regions of Poland. The results showed that for Ce as the most abundant among the RREs in edible caps, the mean concentration was at 0.18±0.29mgkg(-1)dry biomass. The mean concentration for Σ16 REEs determined in caps of fungus was 0.50mgkg(-1)dry biomass and in whole fruiting bodies was 0.75mgkg(-1)dry biomass. From a point of view by consumer, the amounts of REEs contained in edible caps of M. procera could be considered small. Hence, eating a tasty caps of this fungus would not result in a health risk for consumer because of exposure to the REEs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940016379&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2527%2527rare%2Bearths%2527%2527','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940016379&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2527%2527rare%2Bearths%2527%2527"><span>Rare <span class="hlt">Earth</span> <span class="hlt">elements</span> in individual minerals in Shergottites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wadhwa, Meenakshi; Crozaz, Ghislaine</p> <p>1993-01-01</p> <p>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 <span class="hlt">Earth</span>. Rare <span class="hlt">earth</span> <span class="hlt">element</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034362','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034362"><span><span class="hlt">Geochemistry</span> of environmentally sensitive trace <span class="hlt">elements</span> in Permian coals from the Huainan coalfield, Anhui, China</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Chen, J.; Liu, Gaisheng; Jiang, M.; Chou, C.-L.; Li, H.; Wu, B.; Zheng, Lingyun; Jiang, D.</p> <p>2011-01-01</p> <p>To study the geochemical characteristics of 11 environmentally sensitive trace <span class="hlt">elements</span> in the coals of the Permian Period from the Huainan coalfield, Anhui province, China, borehole samples of 336 coals, two partings, and four roof and floor mudstones were collected from mineable coal seams. Major <span class="hlt">elements</span> and selected trace <span class="hlt">elements</span> were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation atomic absorption spectrometry (HAAS). The depositional environment, abundances, distribution, and modes of occurrence of trace <span class="hlt">elements</span> were investigated. Results show that clay and carbonate minerals are the principal inorganic constituents in the coals. A lower deltaic plain, where fluvial channel systems developed successively, was the likely depositional environment of the Permian coals in the Huainan coalfield. All major <span class="hlt">elements</span> have wider variation ranges than those of Chinese coals except for Mg and Fe. The contents of Cr, Co, Ni, and Se are higher than their averages for Chinese coals and world coals. Vertical variations of trace <span class="hlt">elements</span> in different formations are not significant except for B and Ba. Certain roof and partings are distinctly higher in trace <span class="hlt">elements</span> than underlying coal bench samples. The modes of occurrence of trace <span class="hlt">elements</span> vary in different coal seams as a result of different coal-forming environments. Vanadium, Cr, and Th are associated with aluminosilicate minerals, Ba with carbonate minerals, and Cu, Zn, As, Se, and Pb mainly with sulfide minerals. ?? 2011 Elsevier B.V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.170...17B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.170...17B"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> and neodymium isotopes in world river sediments revisited</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>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.</p> <p>2015-12-01</p> <p>Over the past decades, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) and their radioactive isotopes have received tremendous attention in sedimentary <span class="hlt">geochemistry</span>, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on <span class="hlt">elemental</span> 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 <span class="hlt">Earth</span> 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 ΔεNd(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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/pp/1566/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/pp/1566/report.pdf"><span><span class="hlt">Geochemistry</span> of minor <span class="hlt">elements</span> in the Monterey Formation, California; seawater chemistry of deposition</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Piper, D.Z.; Isaacs, C.M.</p> <p>1995-01-01</p> <p>Approximately 24 samples of the Monterey Formation, Southern California, have been analyzed for their major-<span class="hlt">element</span> oxide and minor-<span class="hlt">element</span> content. These analyses allow identification of a detrital fraction, composed of terrigenous quartz, clay minerals, and other Al silicate minerals, and a marine fraction, composed of biogenic silica, calcite, dolomite, organic matter, apatite, and minor amounts of pyrite. The minor-<span class="hlt">element</span> contents in the marine fraction alone are interpreted to have required, at the time of deposition, a high level of primary productivity in the photic zone and denitrifying bacterial respiration in the bottom water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18639916','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18639916"><span>Effects of rare <span class="hlt">earth</span> <span class="hlt">elements</span> on the distribution of mineral <span class="hlt">elements</span> and heavy metals in horseradish.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Lihong; Huang, Xiaohua; Zhou, Qing</p> <p>2008-09-01</p> <p>In order to investigate the effects of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) on horseradish, the distribution of the mineral <span class="hlt">elements</span> and heavy metals in different organs of horseradish have been studied by using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Meanwhile, three variable major parameters, namely the concentration of REEs, the type of REEs, and the growth stage of plant were chosen. The results indicated that the test REEs, Ce(III) and Tb(III), could be accumulated in leaves, stems and roots of horseradish. In addition, we found that the content of mineral <span class="hlt">elements</span> was increased in horseradish treated with 20mgl(-1) of Ce(III), but not those with the 20mgl(-1) of Tb(III). Moreover, the content of mineral <span class="hlt">elements</span> in horseradish was decreased with the increasing concentration of REEs (100, 300mgl(-1)). Furthermore, we found that there were the opposite effects on the content of the heavy metals in horseradish treated with REEs. Finally, we found that the effect of REEs on the accumulation of REEs, and the content of mineral <span class="hlt">elements</span> or heavy metals of horseradish during vigorous growth stage, no matter positive or negative, was more obvious than that of the other growth stages. These results demonstrated that the distribution behaviors of mineral <span class="hlt">elements</span> and heavy metals in horseradish can be affected by the type and concentration of REEs, and the growth period of plant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhSRv...1...56H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhSRv...1...56H"><span>Separation/Preconcentration Techniques for Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Bin; He, Man; Chen, Beibei; Jiang, Zucheng</p> <p>2016-10-01</p> <p>The main aim of this chapter exactly characterizes the contribution. The analytical chemistry of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) very often is highly complicated and the determination of a specific <span class="hlt">element</span> is impossible without a sample pre-concentration. Sample preparation can be carried out either by separation of the REEs from the matrix or by concentrating the REEs. The separation of REEs from each other is mainly made by chromatography. At the beginning of REE analysis, the method of precipitation/coprecipitation was applied for the treatment of REE mixtures. The method is not applicable for the separation of trace amounts of REEs. The majority of the methods used are based on the distribution of REEs in a two-phase system, a liquid-liquid or a liquid-solid system. Various techniques have been developed for the liquid-liquid extraction (LLE), in particular the liquid phase micro-extraction. The extraction is always combined with a pre-concentration of the REEs in a single drop of extractant or in a hollow fiber filled with the extractant. Further modified techniques for special applications and for difficult REE separation have been developed. Compared to the LLE, the solid phase micro-extraction is preferred. The method is robust and easy to handle, in which the solid phase loaded with the REEs can be used directly for subsequent determination methods. At present, very new solid materials, like nanotubes, are developed and tested for solid phase extraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMPP13B2118M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMPP13B2118M"><span>Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span> of the Dolomite Member of the Neoproterozoic Ibex Formation, Death Valley National Park, CA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, E. E.; Lanids, J. D.; Quicksall, A. N.; Ddamba, I.</p> <p>2012-12-01</p> <p>This work examines the major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the pink, laminated Dolomite Member of the Neoprotoerozic Ibex Formation, sampled at high resolution in the Ibex Hills of Death Valley, California. The Dolomite Member of the Ibex Formation directly overlies a basal conglomerate which has lead Corsetti and Kaufman (2005) to speculate that the juxtaposition of these units represents a diamictite - cap carbonate pair. Cap carbonates are inferred to represent deposition under high alkalinity conditions in the shallow ocean at the termination of low latitude glaciation. Increased alkalinity may be driven by the post glacial overturn of anoxic water masses. Here we infer paleoredox conditions during the deposition of the Dolomite Member of the Ibex Formation using trace metal enrichments. The Dolomite Member shows enrichments of Ni, Mo, Fe, Cu, V, Co, and Ba near the base of the unit, and also has a weak overall enrichment in Mn. The enrichment of these metals suggests a period of anoxia during the initial deposition of the Dolomite, and may signal the introduction of basin brines to the shallow ocean during marine transgression. These data are consistent with patterns observed in other cap carbonates worldwide, and support the speculation that the Dolomite Member is a cap carbonate. Alternatively, trace metal enrichments may reflect diagenetic alteration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24202842','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24202842"><span>Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of soils and plants in Kenyan conservation areas and implications for wildlife nutrition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maskall, J; Thornton, I</p> <p>1991-06-01</p> <p>Trace <span class="hlt">element</span> concentrations in soils, plants and animals in National Parks and Wildlife Reserves in Kenya are assessed using geochemical mapping techniques. Soil trace <span class="hlt">element</span> concentrations are shown to be related to soil parent material and possibly to pedological and hydrological factors. At Lake Nakuru National Park, plant trace <span class="hlt">element</span> concentrations vary with plant species and the geochemical conditions that influence uptake are discussed. Impala at Lake Nakuru National Park and black rhino at Solio Wildlife Reserve are shown to have a lower blood copper status than animals from other areas. The trace <span class="hlt">element</span> status of wildlife is assessed also with respect to critical concentrations used for domestic ruminants. It is suggested that at Lake Nakuru National Park, the low soil copper content and high molybdenum content of some plants contributes to the low copper status of impala and may also influence the nutrition of other species.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006Litho..88....1C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006Litho..88....1C"><span>Pb and rare <span class="hlt">earth</span> <span class="hlt">element</span> diffusion in xenotime</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cherniak, D. J.</p> <p>2006-05-01</p> <p>Diffusion of Pb and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> Sm, Dy and Yb have been characterized in synthetic xenotime under dry conditions. The synthetic xenotime was grown via a Na 2CO 3-MoO 3 flux method. The sources of diffusant for the rare <span class="hlt">earth</span> diffusion experiments were REE phosphate powders, with experiments run using sources containing a single REE. For Pb, the source consisted a mixture of YPO 4 and PbTiO 3. Experiments were performed by placing source and xenotime in Pt capsules, and annealing capsules in 1 atm furnaces for times ranging from 30 min to several weeks, at temperatures from 1000 to 1500 °C. The REE and Pb distributions in the xenotime were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relations are obtained for diffusion in xenotime, normal to (101): D=1.5×10exp⁡(-441±12 kJmol/R⁢T)ms.D=9.0×10exp⁡(-349±16 kJmol/R⁢T)ms.D=3.9×10exp⁡(-362±13 kJmol/R⁢T)ms. Diffusivities among the REE do not differ greatly in xenotime over the investigated temperature range, in contrast to findings for the REE in zircon [Cherniak, D.J., Hanchar, J.M., Watson, E.B., 1997. Rare <span class="hlt">earth</span> diffusion in zircon. Chem. Geol. 134, 289-301.], where the LREE diffuse more slowly, and with higher activation energies for diffusion, than the heavier rare <span class="hlt">earths</span>. In zircon, these differences among diffusion of the rare <span class="hlt">earths</span> are attributed to the relatively large size of the REE with respect to Zr, for which they likely substitute in the zircon lattice. With the systematic increase in ionic radius from the heavy to lighter REE, this size mismatch becomes more pronounced and diffusivities of the LREE are as consequence slower. Although xenotime is isostructural with zircon, the REE are more closely matched in size to Y, so in xenotime this effect appears much smaller and the REE diffuse at similar rates. In addition, the process of diffusion in xenotime likely involves simple REE + 3 → Y + 3 exchange, without charge compensation as needed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H34C..01M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H34C..01M"><span>Rare <span class="hlt">earth</span> <span class="hlt">element</span> analysis indicates micropollutants in an urban estuary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohajerin, T. J.; Johannesson, K. H.; Kolker, A.; Burdige, D. J.; Chevis, D.</p> <p>2011-12-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> 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 <span class="hlt">elements</span> 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 <span class="hlt">element</span> concentions, including the REEs, by magnetic sector ICP-MS. The attached figure shows the Gd anomaly present in the particulate (>0.45μm) fraction. Upper continental crust (UCC)-normalized plots of colloidal REEs (0.02μm - 0.45μm) 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.S41A1894M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.S41A1894M"><span>Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> reveal past earthquakes on limestone normal faults</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manighetti, I.; Boucher, E.; Chauvel, C.; Schlagenhauf, A.; Benedetti, L.</p> <p>2009-12-01</p> <p>In 2008, we suggested that the chemical composition of the rocks which form well preserved, seismically exhumed fault scarps might record past major earthquakes (Carcaillet et al., 2008) because those scarp surfaces consist of a vertical succession of zones that have been exposed at different times by the repeating earthquakes, thus weathered over different time spans. In this pioneer study, we validated this hypothesis using the changes in chemical compositions (major and trace <span class="hlt">elements</span>) of 15 carbonate rock samples collected from the base to the top of the seismically exhumed, 10 m-high Magnola normal fault scarp (Abruzzes, Central Italy). However, the number of available samples was insufficient to fully assess the validity of the model. Here we present trace <span class="hlt">element</span> data on 27 additional samples collected systematically every 25 cm along the Magnola scarp, as well as on 7 scarp samples buried below the colluvium hence representing the first 4 meters of the scarp before exhumation. The scarp rocks buried in the first meter of the ground appear significantly enriched in Rare <span class="hlt">Earth</span> <span class="hlt">elements</span> (REE): they contain 60% more REE than the rocks located either deeper in the ground or immediately above the ground level. This concentration peak most probably results from enrichment of the scarp rocks by interaction with the impurity-doped, acidic, upper soil. Above the ground surface and along the scarp, most <span class="hlt">element</span> concentrations (70%) decrease up-dip, generally by more than 50%; we attribute this trend to leaching and dissolution-recrystallization of purer calcite through time. The top of the scarp having been exposed for a longer period of time, its surface lost more of the trace <span class="hlt">elements</span> contained in the rocks. However, the upward decrease in REE contents is not linear and 4 REE concentration peaks can be recognized along the exposed scarp. The position of these 4 peaks coincide with the zones identified by Schlagenhauf et al. (2009) and Palumbo et al. (2004) as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011819','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011819"><span>Petrology and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Honolulu volcanics, Oahu: implications for the oceanic mantle below Hawaii.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Clague, D.A.; Frey, F.A.</p> <p>1982-01-01</p> <p>These volcanic rocks are the products of small-volume, late-stage vents along rifts cutting the older massive Koolan tholeiitic shield on Oahu. Most of the lavas and tuffs have the geochemical features expected of near-primary magmas derived from a peridotite source with olivine Fo87-89, e.g. 100 Mg/(Mg + Fe2+) > 65, Ni > 250 p.p.m. and the presence of ultramafic mantle xenoliths at 18 of the 37 vents. Thus the <span class="hlt">geochemistry</span> of the alkali olivine basalt, basanite, nephelinite and nepheline melilitite lavas and tuffs of these Honolulu volcanic rocks has been used to deduce the composition of their mantle source and the conditions under which they were generated by partial melting in the mantle. New major- and trace-<span class="hlt">element</span> analyses for 31 samples are tabulated and indicate derivation by partial melting of a garnet (<10%) lherzolite source which was isotopically homogeneous and compositionally uniform for most major and trace <span class="hlt">elements</span>, though apparently heterogeneous in TiO2, Zr, Hf, Nb and Ta (due perhaps to the low inferred degrees of melting which failed to exhaust the source in minor residual phases). In comparison with estimates of a primordial mantle composition and the mantle source of MORB, the garnet peridotite source of these Honolulu volcanics was increasingly enriched in the sequence heavy REE, Y, Tb, Ti, Sm, Zr and Hf, for which a multi-stage history is required. This composition differs from the source of the previously erupted tholeiitic shield, nor is it represented in the upper-mantle xenoliths in the lavas and tuff of the unit.-R.A.H.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7084C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7084C"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> exploitation, geopolitical implications and raw materials trading</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chemin, Marie-Charlotte</p> <p>2015-04-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) correspond to seventeen <span class="hlt">elements</span> 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 <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earths</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V11A2509G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V11A2509G"><span>Deciphering tectonic provenance signatures from the trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of igneous zircon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grimes, C. B.; Wooden, J. L.; Vazquez, J. A.</p> <p>2011-12-01</p> <p>The ability to correlate stable isotope ratios and trace <span class="hlt">element</span> signatures with age on single crystals, coupled with resistance to chemical and physical weathering make zircon a useful complement in a wide range of geologic investigations. Zircon trace <span class="hlt">element</span> concentrations broadly reflect parental magma composition, although studies show that crystal chemistry also imparts a significant control on the shape of REE patterns. Concentrations of select <span class="hlt">elements</span> (e.g., Hf) and various trace <span class="hlt">element</span> ratios (e.g., Th/U, Yb/Gd, Eu/Eu*) commonly correlate with crystallization temperature (from Ti-in-zircon thermometry) for suites of zircon precipitated during magmatic fractionation in zircon-saturated systems. Other trace <span class="hlt">element</span> ratios, primarily U/Yb and Th/Yb plotted against Hf or Y discriminate zircon sampled in situ from mid-ocean ridges from those formed in arc-related ('continental') settings. However, these geochemical discriminations are limited in that ~20% of published mid-ocean ridge zircon compositions plot within the 'continental' zircon field and they fail to distinguish zircon from other magmatic settings such as ocean islands. To improve geochemical zircon discrimination diagrams for diverse tectonic environments, trace <span class="hlt">element</span> criteria that distinguish lavas from different tectonic settings are considered along with a broad suite of <span class="hlt">elements</span> routinely measured by the Stanford-USGS SHRIMP-RG ion probe. Arc-related magmas exhibit enrichment in large ion lithophile (LIL) <span class="hlt">elements</span> (i.e., U, Th) with respect to typical MORB, and are depleted in niobium (Nb) with respect to both OIB and MORB lavas. OIB lavas are typically enriched in LIL with respect to MORB, but lack the Nb-depletion characteristic of arcs. The ratios U/Yb, Yb/Nb, and Th/Nb can therefore be used to discriminate lavas from these different settings. Discrimination diagrams based on these <span class="hlt">elemental</span> ratios in zircon also define separate (though partly overlapping) fields for modern mid</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.8541B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.8541B"><span>Targeting heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> in carbonatite complexes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Broom-Fendley, S.; Wall, F.; Gunn, A. G.; Dowman, E.</p> <p>2012-04-01</p> <p>The world's main sources of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">earths</span> (LREE). The heavy rare <span class="hlt">earths</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/194767','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/194767"><span>Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> in water from selected springs in Death Valley National Park, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kreamer, D.K.; Hodge, V.F.; Rabinowitz, I.; Johannesson, K.H.; Stetzenbach, K.J.</p> <p>1996-01-01</p> <p>Concentrations of 40 trace <span class="hlt">elements</span> and other constituents in ground water from springs in Death Valley National Park were measured to investigate whether trace <span class="hlt">element</span> composition of the ground water can be related to the aquifer materials. Samples from these springs were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) for the trace <span class="hlt">elements</span> and by ion chromatography (IC) for the major anions. A Principal Component Analysis was performed on the data set. Surprise and Scotty`s Springs formed one group; Texas, Nevares, and Travertine Springs formed another group; and Mesquite Springs did not group with any of the others. Scotty`s and Surprise Spring issued from volcanic rocks; Texas, Nevares, and Travertine discharge from carbonate rocks; and Mesquite Spring is located in alluvial basin-fill deposits. The first three components in each principal Component Analysis accounted for approximately 95% of the variance in the data set. The Principal Component Analysis suggests that ground water inherits its trace <span class="hlt">element</span> composition from the rocks or aquifer material with which it has interacted and may be used for the purpose of identifying ground-water movement and source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.7134D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.7134D"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> as a fingerprint of soil components solubilization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davranche, M.; Grybos, M.; Gruau, G.; Pédrot, M.; Dia, A.</p> <p>2009-04-01</p> <p>The retention of rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) in the soil profile are mainly controlled by three factors, (i) the stability of the primary REE-carrying minerals, (ii) the presence of secondary phases as clays and Fe- and Mn-oxyhydroxides and (ii) the concentration of colloidal organic matter (OM). Considering that each soil phases (mineral or organic) displays (ii) various surface properties, such as specific area, surface sites density and nature and (ii) their own REE distribution inherited from the rock weathering, their mobilization through various chemical reactions (dissolution, colloidal release….) may involve the development of various shaped REE patterns in the soil solutions. REE fractionation from the different soil phases may therefore be used to identify the response of the soil system to a particular chemical process such as reductive and/or acidic dissolution. To test this purpose, an organic-rich wetland soil sample was incubated under anaerobic condition at both pH 5 and uncontrolled pH. The REE patterns developed in the soil solution were then compared to the REE patterns obtained through either aerobic at pH 3 and 7 incubations or a chemical reduction experiment (using hydroxylamine). REE patterns in anaerobic and aerobic at pH 7 experiments exhibited the same middle rare <span class="hlt">earth</span> <span class="hlt">element</span> (MREE) downward concavity significant of the complexation of REE with soil OM. By contrast, under acidic condition, the REE pattern exhibited a positive Eu anomaly due to the dissolution of soil feldspar. Finally, REE pattern obtained from the chemical reducing experiment showed an intermediary flat shape corresponding to a mixing between the soil organic and mineral phases dissolution. The comparison of the various REE pattern shapes allowed to conclude that (i) biological reduction of wetland soil involved amorphous Fe(III) colloids linked to OM and, (ii) that the REE mobility was controlled by the dynamic of OM in wetland soil. They also evidence the potential of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.B21C0371R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.B21C0371R"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in scleractinian cold-water corals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raddatz, J.; Liebetrau, V.; Hathorne, E. C.; Rüggeberg, A.; Dullo, W.; Frank, M.</p> <p>2012-12-01</p> <p>The Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (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</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5328M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5328M"><span>Geochemical behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and other trace <span class="hlt">elements</span> in the Amazon River</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Merschel, Gila; Bau, Michael; Dantas, Elton Luiz</p> <p>2014-05-01</p> <p>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 <span class="hlt">elements</span>, especially particle-reactive <span class="hlt">elements</span> such as the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">elements</span> 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 <span class="hlt">elements</span>, 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 <span class="hlt">elements</span>. While</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhSRv...1...63S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhSRv...1...63S"><span>Automated Quantitative Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Mineralogy by Scanning Electron Microscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sindern, Sven; Meyer, F. Michael</p> <p>2016-09-01</p> <p>Increasing industrial demand of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) stems from the central role they play for advanced technologies and the accelerating move away from carbon-based fuels. However, REE production is often hampered by the chemical, mineralogical as well as textural complexity of the ores with a need for better understanding of their salient properties. This is not only essential for in-depth genetic interpretations but also for a robust assessment of ore quality and economic viability. The design of energy and cost-efficient processing of REE ores depends heavily on information about REE <span class="hlt">element</span> deportment that can be made available employing automated quantitative process mineralogy. Quantitative mineralogy assigns numeric values to compositional and textural properties of mineral matter. Scanning electron microscopy (SEM) combined with a suitable software package for acquisition of backscatter electron and X-ray signals, phase assignment and image analysis is one of the most efficient tools for quantitative mineralogy. The four different SEM-based automated quantitative mineralogy systems, i.e. FEI QEMSCAN and MLA, Tescan TIMA and Zeiss Mineralogic Mining, which are commercially available, are briefly characterized. Using examples of quantitative REE mineralogy, this chapter illustrates capabilities and limitations of automated SEM-based systems. Chemical variability of REE minerals and analytical uncertainty can reduce performance of phase assignment. This is shown for the REE phases parisite and synchysite. In another example from a monazite REE deposit, the quantitative mineralogical parameters surface roughness and mineral association derived from image analysis are applied for automated discrimination of apatite formed in a breakdown reaction of monazite and apatite formed by metamorphism prior to monazite breakdown. SEM-based automated mineralogy fulfils all requirements for characterization of complex unconventional REE ores that will become</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002637','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002637"><span>Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Partitioning in Lunar Minerals: An Experimental Study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McIntosh, E. C.; Rapp, J. F.; Draper, D. S.</p> <p>2016-01-01</p> <p>The partitioning behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) between minerals and melts is widely used to interpret the petrogenesis and geologic context of terrestrial and extra-terrestrial samples. REE are important tools for modelling the evolution of the lunar interior. The ubiquitous negative Eu anomaly in lunar basalts is one of the main lines of evidence to support the lunar magma ocean (LMO) hypothesis, by which the plagioclase-rich lunar highlands were formed as a flotation crust during differentiation of a global-scale magma ocean. The separation of plagioclase from the mafic cumulates is thought to be the source of the Eu depletion, as Eu is very compatible in plagioclase. Lunar basalts and volcanic glasses are commonly depleted in light REEs (LREE), and more enriched in heavy REEs (HREE). However, there is very little experimental data available on REE partitioning between lunar minerals and melts. In order to interpret the source of these distinctive REE patterns, and to model lunar petrogenetic processes, REE partition coefficients (D) between lunar minerals and melts are needed at conditions relevant to lunar processes. New data on D(sub REE) for plagioclase, and pyroxenes are now available, but there is limited available data for olivine/melt D(sub REE), particularly at pressures higher than 1 bar, and in Fe-rich and reduced compositions - all conditions relevant to the lunar mantle. Based on terrestrial data, REE are highly incompatible in olivine (i.e. D much less than 1), however olivine is the predominant mineral in the lunar interior, so it is important to understand whether it is capable of storing even small amounts of REE, and how the REEs might be fractionatied, in order to understand the trace <span class="hlt">element</span> budget of the lunar interior. This abstract presents results from high-pressure and temperature experiments investigating REE partitioning between olivine and melt in a composition relevant to lunar magmatism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14582968','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14582968"><span>Effects of spraying rare <span class="hlt">earths</span> on contents of rare <span class="hlt">Earth</span> <span class="hlt">elements</span> and effective components in tea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Dongfeng; Wang, Changhong; Ye, Sheng; Qi, Hongtao; Zhao, Guiwen</p> <p>2003-11-05</p> <p>Rare <span class="hlt">earth</span> (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 <span class="hlt">earth</span> <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002NIMPB.189..209G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002NIMPB.189..209G"><span><span class="hlt">Elemental</span> <span class="hlt">geochemistry</span> of wind-erodible playa sediments, Owens Lake, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gill, Thomas E.; Gillette, Dale A.; Niemeyer, Tezz; Winn, Russell T.</p> <p>2002-04-01</p> <p>Wind erosion of the dried bed (playa) of Owens Lake, California is an extremely intense source of mineral aerosol, transporting dust hundreds of kilometers downwind to critical ecological areas and several cities. A dust-producing site on the playa was studied over a four-year period to document the processes associated with aerosol emission. The playa takes on a variety of sedimentary forms and phases with surface crusts of differing susceptibilities to wind erosion. The sediments are classed into three general categories based on appearance: soft (saline), loose with drifting sand (salt-silt-clay), and hard and clean (silt-clay). Sediment samples were collected over a two-year period as the study site cycled through all three crust types, and the samples were crushed and analyzed by PIXE. The results indicate that visual appearance and sedimentary structure does not correlate with <span class="hlt">elemental</span> composition. All sediment types contain significant concentrations of various <span class="hlt">elements</span> including sodium, calcium and silicon. Potentially toxic trace <span class="hlt">elements</span> are also found in the sediments. All sediment types contain lead and/or arsenic in tens of parts per million, as well as various other heavy metals. Pb and As levels do not clearly correlate with salt content or sediment type. Arsenic levels may be slightly higher in the crusts with loose material present and potentially lower in the clean hard crusts, while Pb was least frequently detected in the samples with loose material. Future research will add mineralogical and stable isotope analyses to correlate with the PIXE data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70147535','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70147535"><span>Size distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in coal ash</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Scott, Clinton T.; Deonarine, Amrika; Kolker, Allan; Adams, Monique; Holland, James F.</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are utilized in various applications that are vital to the automotive, petrochemical, medical, and information technology industries. As world demand for REEs increases, critical shortages are expected. Due to the retention of REEs during coal combustion, coal fly ash is increasingly considered a potential resource. Previous studies have demonstrated that coal fly ash is variably enriched in REEs relative to feed coal (e.g, Seredin and Dai, 2012) and that enrichment increases with decreasing size fractions (Blissett et al., 2014). In order to further explore the REE resource potential of coal ash, and determine the partitioning behavior of REE as a function of grain size, we studied whole coal and fly ash size-fractions collected from three U.S commercial-scale coal-fired generating stations burning Appalachian or Powder River Basin coal. Whole fly ash was separated into , 5 um, to 5 to 10 um and 10 to 100 um particle size fractions by mechanical shaking using trace-metal clean procedures. In these samples REE enrichments in whole fly ash ranges 5.6 to 18.5 times that of feedcoals. Partitioning results for size separates relative to whole coal and whole fly ash will also be reported. </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013mss..confEMI12C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013mss..confEMI12C"><span>Spectroscopy of Luminescent Crystals Containing Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Meng-Ling; Lii, Kwang-Hwa; Chang, Bor-Chen</p> <p>2013-06-01</p> <p>We have studied the spectroscopy of luminescent crystals containing rare <span class="hlt">earth</span> <span class="hlt">elements</span> such as KEuGe_2O_6, Cs_3EuSi_6O_{15}, K_4[(UO_2)Eu_2(Ge_2O_7)_2], and R_2(C_8H_{10}O_4)_3 (R= Y, Tb, or Eu). The emission and excitation spectra of these compounds were recorded at ambient temperature. These spectra are consistent with the structures which were determined by single crystal X-ray diffraction. Crystals containing hybrid luminescent centers were also synthesized and interesting energy transfer mechanisms were observed. For example, dramatic luminescence quenching was found in KEu_xNd_{1-x}Ge_2O_6 (x= 0.98, 0.96, 0.94, and 0.84) as well as in Cs_3Eu_{0.98}Nd_{0.02}Si_6O_{15}, while different compositions of Y_xEu_yTb_{2-x-y}(C_8H_{10}O_4)_3 exhibit different emission colors. Emission lifetimes were also measured for these compounds, and the results shed light on the energy transfer mechanisms. Detailed results of our research will be presented. P.-L. Chen, P.-Y. Chiang, H.-C. Yeh, B.-C. Chang, and K.-H. Lii, Dalton Trans., 1721 (2008). M.-Y. Hung, Y.-H. Chen, B.-C. Chang, and K.-H. Lii, Chem. Mater. 17, 5743 (2005).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Litho.258....1A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Litho.258....1A"><span>Petrogenesis and origin of modern Ethiopian rift basalts: Constraints from isotope and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ayalew, D.; Jung, S.; Romer, R. L.; Kersten, F.; Pfänder, J. A.; Garbe-Schönberg, D.</p> <p>2016-08-01</p> <p>The source of continental rift-related basalts and their relation to rifting processes is a continuous matter of debate. We present major and trace <span class="hlt">element</span> and Sr, Nd, Hf and Pb isotope data for axial rift basalts from eight volcanic centres (Ayelu, Hertali, Dofan, Fantale, Kone, Bosetti and Gedemsa, from NE to SW) in Afar and Main Ethiopian Rift (MER) to assess their source regions and their genetic relationships. These lavas have geochemical characteristics, i.e., a peak at Ba, Nb and troughs at K and Rb in primitive mantle-normalised multielement diagrams, which are consistent with predominant melting of an amphibole-bearing lithospheric mantle. However, the isotopic compositions for these lavas are heterogeneous (87Sr/86Sr = 0.70354-0.70431, 143Nd/144Nd = 0.51280-0.51294, 176Hf/177Hf = 0.28301-0.28315, 206Pb/204Pb = 18.48-19.31, 207Pb/204Pb = 15.53-15.62, 208Pb/204Pb = 38.61-39.06) and require various mantle reservoirs with distinctive isotopic signatures. The range of isotopic compositions requires the involvement of three distinct source components from the asthenospheric and veined lithospheric mantle. Progressive rifting leads to lithosperic thinning and upwelling of hot asthenospheric mantle, which induces melting of the veined lithospheric mantle. The trace <span class="hlt">element</span> characteristics of the lavas are dominated by the vein material, which has a higher trace <span class="hlt">element</span> content than the surrounding mantle. The isotopic composition of the vein material, however, is not very different from the ambient mantle, giving rise of apparent uncoupling of trace <span class="hlt">element</span> and isotope constraints for the melt source. The uprising basaltic liquids in part inherit a lithospheric trace <span class="hlt">element</span> signature, while their isotopic compositions are mostly unaffected due to short residence times within the lithosphere in context with progressive rifting and lithospheric thinning. Thus, the geochemical and isotope data are consistent with a multi-component source prevailing beneath the Afar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21176850','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21176850"><span>Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of Jurassic coals from Eastern Black Sea Region, NE-Turkey</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cebi, F.H.; Korkmaz, S.; Akcay, M.</p> <p>2009-07-01</p> <p>The majority of coal deposits in the world are of Carboniferous and Tertiary age but Jurassic coals are seldom present. They are also exposed in northern Turkey and occur both at the lower and upper sections of the Liassic-Dogger volcanic- and volcani-clastic series. The coals at the base of the Jurassic units are characterized by higher Ba, Th, Zr, and Cr-Ni and lower S values than those at the top of the units, indicating, in general, laterally consistent trace <span class="hlt">element</span> contents. The vertical distribution of trace <span class="hlt">elements</span> in individual coal seams is also rather consistent. The B contents of coals from the Godul and Norsun areas vary from 1.5 to 4.3 ppm whereas those from the Alansa area are in the range of 95 to 138 ppm. This suggests that the coals in the Godul and Norsun areas were deposited in a swamp environment inundated by the sea from time to time, whereas coals of the Alansa were deposited in a saline environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5224579','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5224579"><span>Stratigraphy and major <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Lassen Volcanic Center, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Clynne, M.A.</p> <p>1984-01-01</p> <p>Detailed geologic mapping of 200 km/sup 2/ in and near Lassen Volcanic National Park, California and reconnaissance of the surrounding area, combined with reinterpretation of data in the literature, allow definition of the Lassen Volcano Center and provide the stratigraphic framework necessary for interpretation of major-<span class="hlt">element</span> chemical data. The Lassen Volcanic Center developed in three stages. Stage I and II produced Brokeoff Volcanic, an andesitic composite cone that erupted mafic andesite to dacite 0.6 to 0.35 my ago. Volcanism then shifted in character and locale. Domes and flows of dacite and rhyodacite, and flows of hybrid andesite were erupted on the northern flank of Brokeoff Volcano during the period from 0.25 my ago to the present; these rocks comprise Stage III of the Lassen Volcanic Center. Rocks of the Lassen Volcanic Center are typical of subduction-related calc-alkaline volcanic rocks emplaced on a continental margin overlying sialic crust. Porphyritic andestic and dacite with high Al/sub 2/O/sub 3/, low TiO/sub 2/, medium K/sub 2/O, and FeO/MgO 1.5-2.0 are the most abundant rock types. Major-<span class="hlt">element</span> chemical trends of rock sequences indicate a mafic to silicic evolution for magmas of the Lassen Volcanic Center, probably owing to crystal fractionation of calc-alkaline basalt. 23 figs., 5 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013127','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013127"><span>Characterization of the Sukinda and Nausahi ultramafic complexes, Orissa, India by platinum-group <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Page, N.J.; Banerji, P.K.; Haffty, J.</p> <p>1985-01-01</p> <p>Samples of 20 chromitite, 14 ultramafic and mafic rock, and 9 laterite and soil samples from the Precambrian Sukinda and Nausahi ultramafic complexes, Orissa, India were analyzed for platinum-group <span class="hlt">elements</span> (PGE). The maximum concentrations are: palladium, 13 parts per billion (ppb); platinum, 120 ppb; rhodium, 21 ppb; iridium, 210 ppb; and ruthenium, 630 ppb. Comparison of chondrite-normalized ratios of PGE for the chromitite samples of lower Proterozoic to Archean age with similar data from Paleozoic and Mesozoic ophiolite complexes strongly implies that these complexes represent Precambrian analogs of ophiolite complexes. This finding is consistent with the geology and petrology of the Indian complexes and suggests that plate-tectonic and ocean basin developement models probably apply to some parts of Precambrian shield areas. ?? 1985.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014569','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014569"><span>Platinum-group <span class="hlt">element</span> <span class="hlt">geochemistry</span> of zoned ultramafic intrusive suites, Klamath Mountains, California and Oregon.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Gray, F.; Page, N.J.; Carlson, C.A.; Wilson, S.A.; Carlson, R.R.</p> <p>1986-01-01</p> <p>Analyses for platinum-group <span class="hlt">elements</span> of the varied rock suites of three Alaskan-type ultramafic to mafic multi-intrusive bodies are reported. Ir and Ru are less than analytical sensitivities of 100 and 20 ppb; Rh is less than or near 1 ppb. Average Pd assays vary among the rocks within intrusive complexes and between the three complexes (6.3, 13.7, 36.4 ppb); average Pt assays vary little among the same samples (27.9, 60.9, 34.0 ppb). Statistically adjusted Pt/(Pt + Pd) ratios increase in each suite from gabbro through clinopyroxenite to olivine-rich rocks, possibly owing to Pd fractionation.-G.J.N.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70098957','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70098957"><span>Major, trace <span class="hlt">element</span> and stable isotope <span class="hlt">geochemistry</span> of synorogenic breccia bodies, Ellsworth Mountains, Antarctica</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Craddock, J.P.; McGillion, M.S.; Webers, G.F.</p> <p>2007-01-01</p> <p>Cambrian carbonates in the Heritage Range of the Ellsworth Mountains, West Antarctica host a series of carbonate-rich breccia bodies that formed contemporaneously with the Permian Gondwanide orogen. The breccia bodies had a three-stage genesis, with the older breccias containing Cambrian limestone (and marble) clasts supported by calcite, whereas the younger breccias are nearly clast-free and composed entirely of matrix calcite. Breccia clasts, calcite matrix and detrital matrix samples were analyzed using x-ray fluorescence (major and trace <span class="hlt">elements</span>), x-ray diffraction, and stable isotopes (C, O) and suggest that the breccias formed as part of a closed geochemical system, at considerable depth, within the Cambrian limestone host as the Ellsworth Mountains deformed into a fold-and-thrust belt along the margin of Gondwana</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011Miner..42...39B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011Miner..42...39B"><span>Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of coals from the Southern Cantabrian Zone (NW Spain): preliminary results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Botor, Dariusz</p> <p>2011-01-01</p> <p>Bituminous to anthracite coals from three small Stephanian intramontane coal-bearing basins (La Magdalena, Cinera-Matallana and Sabero) located along the Sabero-Gordón fault line strike-slip systems of the Southern Cantabrian Zone (SCZ) were examined. Coal rank expressed as mean vitrinite reflectance values of these Stephanian coals is in the range 0.72-3.96%. The vitrinite maceral group exceeds 72 vol. % in all of the coals. The coals are characterized by relatively variable contents of mineral matter and coal-ash. The mineral matter comprises, in the main, clay minerals, carbonates, sulphides and quartz. The coals exhibit medium-high concentrations (see for comparison Ronov et al. 1990; Kabata-Pendias, Pendias 1999; Ketris, Yudovich 2009) of the following <span class="hlt">elements</span> (in ppm): ΣREE (53-205), Ba (300-900), As (11-57), Zn (<50-150), Cr (10-160), Rb (50-145), Co (5-26), Sc (2-24.6), Ce (17-99), Yb (1.3-4.5), Th (2.4-11.9) and U (1.1-8.1), Br (<1-14), Cs (<2-9), Eu (<0,3-1.5), Lu (0.11-0.85) and Sb (0.8-4.8), and relatively low concentrations of Sm (0.6-6.6) and Ta (<1-2). They are also characterised by relatively high Th/U values (1.31-2.29). LREE/HREE values fall in the range 24-44 (average - 30). In contrast, concentrations of Au, Ag, Hg, Ir, Ni, Se, Sn, Sr, and W are below detection limits for the applied INAA method. As the concentrations of <span class="hlt">elements</span> are significantly higher in coal-ash, most are likely related to mineral matter in the coals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAfES.100..335M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAfES.100..335M"><span>Redox control on trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and provenance of groundwater in fractured basement of Blantyre, Malawi</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mapoma, Harold Wilson Tumwitike; Xie, Xianjun; Zhang, Liping</p> <p>2014-12-01</p> <p>Assessment of redox state, pH, environmental isotope ratios (δ18O, δ2H) coupled with PHREEQC speciation modeling investigations were conducted to understand trace <span class="hlt">element</span> geochemical controls in basement complex aquifer in Blantyre, Malawi. Groundwater in the area is typical Ca-Mg-Na-HCO3 type suggesting more of carbonate weathering and significance of carbon dioxide with dissolution of evaporites, silicate weathering and cation exchange being part of the processes contributing to groundwater mineralization. The significance of pH and redox status of groundwater was observed. The groundwater redox state was mostly O2-controlled with few exceptions where mixed (oxic-anoxic) O2-Mn(IV) and O2-Fe(III)/SO4 controlled redox states were modeled. More so, some of the main trace <span class="hlt">element</span> species modeled with PHREEQC varied with respect to pH. For instance vanadium(III) and vanadium(IV) decreased with increase in field pH contrasting the trend observed for vanadium(V). The isotopic composition of the sampled groundwater varied between -5.89‰ and -3.32‰ for δ18O and -36.98‰ and -20.42‰ for δ2H. The δ2H/δ18O and δ18O/Cl- ratios revealed that groundwater is of meteoric origin through vertical recharge and mixing processes. The d-excess value approximated the y-intercept of GMWL of 10 (d-excess = 9.269, SD = 1.240) implying that influence of secondary evaporative processes on isotopic signature of the study area is minimal. Thus, there is evidence to suggest that groundwater chemistry in the studied aquifer is influenced by inherent processes with contribution from human activities and furthermore, the water originates from rainwater recharge. With such results, more studies are recommended to further constrain the processes involved in mineralization through isotopic fractionation investigations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050210032','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050210032"><span>Microbial Paleontology, Mineralogy and <span class="hlt">Geochemistry</span> of Modern and Ancient Thermal Spring Deposits and Their Recognition on the Early <span class="hlt">Earth</span> and Mars"</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Farmer, Jack D.</p> <p>2004-01-01</p> <p>The vision of this project was to improve our understanding of the processes by which microbiological information is captured and preserved in rapidly mineralizing sedimentary environments. Specifically, the research focused on the ways in which microbial mats and biofilms influence the sedimentology, <span class="hlt">geochemistry</span> and paleontology of modem hydrothermal spring deposits in Yellowstone national Park and their ancient analogs. Toward that goal, we sought to understand how the preservation of fossil biosignatures is affected by 1) taphonomy- the natural degradation processes that affect an organism from the time of its death, until its discovery as a fossil and 2) diagenesis- longer-term, post-depositional processes, including cementation and matrix recrystallization, which collectively affect the mineral matrix that contains fossil biosignature information. Early objectives of this project included the development of observational frameworks (facies models) and methods (highly-integrated, interdisciplinary approaches) that could be used to explore for hydrothermal deposits in ancient terranes on <span class="hlt">Earth</span>, and eventually on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V51A2755T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V51A2755T"><span>Rare <span class="hlt">earth</span> <span class="hlt">element</span> budgets in subduction-zone fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsay, A.; Zajacz, Z.; Sanchez-Valle, C.</p> <p>2012-12-01</p> <p>Subduction zone fluids play a fundamental role in the geochemical cycle of the <span class="hlt">Earth</span>. The nature and composition of these fluids are determined by complex processes and still poorly understood. As a result of a variety of metasomatic and partial melting events, arc-related magmas display a typical trace <span class="hlt">element</span> abundance spectrum, in which the rare <span class="hlt">earth</span> <span class="hlt">elements</span>' (REE) signature is an important record of petrogenetic processes. Therefore, investigating the behavior of REE in fluids at high pressure (P) and temperature (T) conditions is crucial for constraining fluid composition, as well as understanding subduction-zone processes in general. However, up to date, the experimental studies on REE solubility and speciation are limited to quite low P-T conditions (300 °C, saturated water vapor pressure) [1]. The theoretical predictions of the stability of REE complexes have been performed up to 350 °C [2] and 1000 °C, 0.5 GPa [3] by the extrapolation of thermodynamic data obtained at ambient conditions. In this study we present new experimental data on REE silicate (REE2Si2O7) solubility in aqueous quartz saturated fluids, containing various ligands, at conditions relevant for subducting slabs (600, 700, 800 °C, 2.6 GPa). The aim of the experiments was to investigate the relative effect of temperature and ligands on the solubility of REE. The experiments were conducted in an end-loaded piston-cylinder apparatus and the fluids were in situ sampled at P-T in the form of primary fluid inclusions in quartz [4]. The gold capsule was typically loaded with a chip of synthetic REE silicate (La,Nd,Gd,Dy,Er,Yb)2Si2O7, an aqueous fluid (~20 wt.%) and a piece of natural quartz. During the experiment (24-48 h) a thermal gradient along the capsule promoted intensive dissolution of quartz at the hottest part and precipitation of new quartz at the cooler part of the capsule, allowing the primary fluid inclusions to be trapped (~30-50 μm). Rubidium and cesium were added to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B11C0036Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B11C0036Y"><span>Investigating Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Systematics in the Marcellus Shale</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, J.; Torres, M. E.; Kim, J. H.; Verba, C.</p> <p>2014-12-01</p> <p>The lanthanide series of <span class="hlt">elements</span> (the 14 rare <span class="hlt">earth</span> <span class="hlt">elements</span>, 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 μg/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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4260943','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4260943"><span>Recovery and Separation of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Using Salmon Milt</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Takahashi, Yoshio; Kondo, Kazuhiro; Miyaji, Asami; Watanabe, Yusuke; Fan, Qiaohui; Honma, Tetsuo; Tanaka, Kazuya</p> <p>2014-01-01</p> <p>Recycling rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GeCoA..96..105A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeCoA..96..105A"><span>Attenuation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in a boreal estuary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Åström, Mats E.; Österholm, Peter; Gustafsson, Jon Petter; Nystrand, Miriam; Peltola, Pasi; Nordmyr, Linda; Boman, Anton</p> <p>2012-11-01</p> <p>This study focuses on attenuation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) when a boreal creek, acidified and loaded with REE and other metals as a result of wetland drainage, empties into a brackish-water estuary (salinity < 6‰). Surface water was collected in a transect from the creek mouth to the outer estuary, and settling (particulate) material in sediment traps moored at selected locations in the estuary. Ultrafiltration, high-resolution ICP-MS and modeling were applied on the waters, and a variety of chemical reagents were used to extract metals from the settling material. Aluminium, Fe and REE transported by the acidic creek were extensively removed in the inner/central estuary where the acidic water was neutralised, whereas Mn was relatively persistent in solution and thus redistributed to particles and deposited further down the estuary. The REE removal was caused by several contemporary mechanisms: co-precipitation with oxyhydroxides (mainly Al but also Fe), complexation with flocculating humic substances and sorption to suspended particles. Down estuary the dissolved REE pool, remaining after removal, was fractionated: the <1 kDa pool became depleted in the middle REE and the colloidal (0.45 μm-1 kDa) pool depleted in the middle and heavy REE. This fractionation was controlled by the removal process, such that those REE with highest affinity for the settling particles became most depleted in the remaining dissolved pool. Modeling, based on Visual MINTEQ version 3.0 and the Stockholm Humic Model after revision and updating, predicted that the dissolved (<0.45 μm) REE pool in the estuary is bound almost entirely to humic substances. Acid sulphate soils, the source of the REE and other metals in the creek water, are widespread on coastal plains worldwide and therefore the REE attenuation patterns and mechanisms identified in the studied estuary are relevant for recognition of similar geochemical processes and conditions in a variety of coastal locations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V22C..07P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V22C..07P"><span>Identification And Interpretation Of Eclogite Protoliths Using Immobile <span class="hlt">Element</span> <span class="hlt">Geochemistry</span>: Some New Methodologies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pearce, J. A.; Robinson, P.; Yang, J.</p> <p>2011-12-01</p> <p>Methodologies for fingerprinting metabasalts have been applied to eclogites with mixed success. Some, including Alpine examples famously studied by Gary Ernst >30 years ago, have been successfully assigned to tectonic settings and the results used to understand the now-disappeared ocean and its margins. Others, however, present two particular, well-documented problems: 1) many are cumulates rather than lavas and so have very low abundances of some <span class="hlt">elements</span> as well as non-liquid compositions; 2) the subduction and exhumation processes can lead to infiltration of the protolith by subduction- and crustally-derived fluids/melts before and after eclogite-facies metamorphism and so impart apparent subduction or continental character even when none existed. Here we demonstrate new methodologies for dealing with these issues, taking as an example the eclogites from the Chinese Continental Scientific Drilling (CCSD) Deep Borehole. We adopt a set of immobile <span class="hlt">element</span> proxies that highlight the presence and behaviour of particular cumulate phases (e.g. Cr for chromite, Ni for olivine, Sc,V for clinopyroxene, Ti,V for oxide, Ga for plagioclase, P and Zr for apatite and zircon, Nb for interstitial melt). Using a training data set from well-studied cumulate sequences such as Bushveld and Skaergaard, we can assign protolith rock names on the basis of these proxy <span class="hlt">elements</span>. Variation diagrams enable us identify the crystallization sequence of the plutonic protolith, itself a function of the original tectonic setting. For example, the Borehole contains a thick, eclogite-facies cumulate sequence which we can reconstruct in detail as a layered complex containing cumulate dunite and peridotite, mela-troctolite, troctolite, gabbro, ferrogabbro, ferrodiorite, quartz-diorite and tonalite. The iron enrichment and inferred saturation sequence of chr+ol-plag-cpx-mt-ap-zr are characteristic of low-oxygen fugacity, tholeiitic MORB and continental margin intrusions. In this, and more easily in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2011/1256/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2011/1256/"><span>Carbonatite and alkaline intrusion-related rare <span class="hlt">earth</span> <span class="hlt">element</span> deposits–A deposit model</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Verplanck, Philip L.; Van Gosen, Bradley S.</p> <p>2011-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> are not as rare in nature as their name implies, but economic deposits with these <span class="hlt">elements</span> are not common and few deposits have been large producers. In the past 25 years, demand for rare <span class="hlt">earth</span> <span class="hlt">elements</span> has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare <span class="hlt">earth</span> <span class="hlt">elements</span> come from only a few sources. China produces more than 95 percent of the world's supply of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Because of China's decision to restrict exports of these <span class="hlt">elements</span>, the price of rare <span class="hlt">earth</span> <span class="hlt">elements</span> has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare <span class="hlt">earth</span> <span class="hlt">elements</span> deposits, and identifying and quantifying our nation's rare <span class="hlt">earth</span> <span class="hlt">elements</span> resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. 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 <span class="hlt">elements</span>, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare <span class="hlt">earth</span> <span class="hlt">elements</span>, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/tei/0151/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/tei/0151/report.pdf"><span>Summary of the research work of the Trace <span class="hlt">Elements</span> Section, <span class="hlt">Geochemistry</span> and Petrology Branch, for the period January 1-March 31, 1951</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rabbitt, John C.</p> <p>1951-01-01</p> <p>This report summarized the research work of the Trace <span class="hlt">Elements</span> Section, <span class="hlt">Geochemistry</span> and Petrology Branch for the period January 1 - March 31, 1951. Work before that is summarized in an earlier report, "Summary of the research work of the Trace <span class="hlt">Elements</span> Section, <span class="hlt">Geochemistry</span> and Petrology Branch, for the period April 1, 1948 - December 31, 1950," by John C. Rabbitt (U.S. Geol. Survey Trace <span class="hlt">Elements</span> Investigations Rept. 148, January 1951). This report will be referred to as TEIR 148. In TEIR 148 the purpose of each project was described and it is not thought necessary to repeat that material. The research work of the section consists of laboratory and related field studies in the following fields: 1. Mineralogic and petrologic investigations of radioactive rocks, minerals, and ores. 2. Investigations of chemical methods of analysis for uranium, thorium, and other <span class="hlt">elements</span> and compounds in radioactive materials, and related chemical problems. 3. Investigations of spectographic method of analysis for a wide variety of <span class="hlt">elements</span> in radioactive materials. 4. Investigation of radiometric methods of analysis is applied to radioactive materials. It should be emphasized that the work undertaken so far is almost entirely in the nature of investigations supporting the field appraisal of known uraniferous deposits. A program of more fundamental research, particularly in the mineralogy and <span class="hlt">geochemistry</span> of uranium, is now being drawn up and will be submitted for approval soon. This report does not deal with the routine analytical work of the Section nor the public-sample program. The analytical work will be summarized in a report to be issued after the end of fiscal year 1951, and a report on the public-sample program is in process. Special thanks are due members of the Section who are engaged in the research work and who have supplied material for this report, the Early Ingerson, Chief of the <span class="hlt">Geochemistry</span> and Petrology Branch for his critical review, to Jane Titcomb of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070010740','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070010740"><span>Crystal Field Effects and Siderophile <span class="hlt">Element</span> Partitioning: Implications for Mars HSE <span class="hlt">Geochemistry</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, John H.; Malavergne, V.; Neal, C. R.</p> <p>2007-01-01</p> <p>Analyses of martian (SNC) meteorites indicate that Pt abundances do not vary much compared to other highly siderophile <span class="hlt">elements</span> (HSE). Therefore, Jones et al. [1] inferred that D(Pt) during basalt petrogenesis was of order unity. This inference was at odds with previously published experiments that gave a D(sub ol/liq) for Pt of approx. 0.01 [2]. Because olivine is likely to be an important constituent of any reasonable martian mantle, the implication of these findings is that minor minerals must have D(Pt) much greater than 1, which seemed improbable. However, not only did the SNC evidence point to a D(sub ol/liq) approx. equal to 1, but so did plots of D(sub ol/liq) vs. ionic radius (Onuma diagram). The ionic radius of Pt(2+) suggested that D(sub ol/liq) for Pt was of order unity, in agreement with the inferences from SNC meteorites. New experiments have failed to detect measurable Pt in olivine, even at high oxygen fugacities [3]. Therefore, some other parameter, other than ionic charge and radius, must hold sway during olivine liquid partitioning of Pt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CoMP..171...69P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CoMP..171...69P"><span>Elucidating the magmatic history of the Austurhorn silicic intrusive complex (southeast Iceland) using zircon <span class="hlt">elemental</span> and isotopic <span class="hlt">geochemistry</span> and geochronology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Padilla, A. J.; Miller, C. F.; Carley, T. L.; Economos, R. C.; Schmitt, A. K.; Coble, M. A.; Wooden, J. L.; Fisher, C. M.; Vervoort, J. D.; Hanchar, J. M.</p> <p>2016-09-01</p> <p>The Austurhorn intrusive complex (AIC) in southeast Iceland comprises large bodies of granophyre and gabbro, and a mafic-silicic composite zone (MSCZ) that exemplifies magmatic interactions common in Icelandic silicic systems. Despite being one of Iceland's best-studied intrusions, few studies have included detailed analyses of zircon, a mineral widely recognized as a valuable tracer of the history and evolution of its parental magma(s). In this study, we employ high spatial resolution zircon <span class="hlt">elemental</span> and isotopic <span class="hlt">geochemistry</span> and U-Pb geochronology as tools for elucidating the complex construction and magmatic evolution of Austurhorn's MSCZ. The trace <span class="hlt">element</span> compositions of AIC zircon crystals form a broad but coherent array that partly overlaps with the geochemical signature for zircons from Icelandic silicic volcanic rocks. Typical of Icelandic zircons, Hf concentrations are relatively low (<10,000 ppm) and Ti concentrations range from 5 to 40 ppm (Ti-in-zircon model temperatures = 761-981 °C). Zircon δ18O values vary from +2.2 to +4.8 ‰, consistent with magmatic zircons from other Icelandic silicic rocks, and preserve evidence for recycling of hydrothermally altered crust as a significant contribution to the generation of silicic magmas within the AIC. Zircon ɛ Hf values generally range from +11 to +15. This range overlaps with that of Icelandic basalts from off-rift settings as well as the least depleted rift basalts, suggesting that the AIC developed within a transitional rift environment. In situ zircon U-Pb ages yield a weighted mean of 6.52 ± 0.03 Ma for the entire complex, but span a range of ~320 kyr, from 6.35 ± 0.08 to 6.67 ± 0.06 Ma (2 σ SE). Gabbros and the most silicic units make up the older part of this range, while granophyres and intermediate units make up the younger part of the complex, consistent with field relationships. We interpret the ~320 kyr range in zircon ages to represent the approximate timescale of magmatic construction</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.5062H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.5062H"><span><span class="hlt">Geochemistry</span> of arsenic and other trace <span class="hlt">elements</span> in a volcanic aquifer system of Kumamoto Area, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hossain, Shahadat; Hosono, Takahiro; Shimada, Jun</p> <p>2015-04-01</p> <p>Total arsenic (As), As(III) species, dissolved organic carbon (DOC), methane (CH4), sulfur isotope ratios of sulfate (δ34SSO4), major ions and trace <span class="hlt">elements</span> were measured in groundwater collected from boreholes and wells along the flow lines of western margins of Kumamoto basin, at central part of Kyushu island in southern Japan. Kumamoto city is considered as the largest groundwater city in Japan. 100% people of this city depends on groundwater for their drinking purpose. In this study, we used trace <span class="hlt">elements</span> data and δ34SSO4 values to better understand the processes that are likely controlling mobilization of As in this area. Arsenic concentrations ranges from 1 to 60.6 μg/L. High concentrations were found in both shallow and deep aquifers. The aquifers are composed of Quaternary volcanic (pyroclastic) flow deposits. In both aquifers, groundwaters evolve along the down flow gradient from oxidizing conditions of recharge area to the reducing conditions of stagnant area of Kumamoto plain. 40% samples from the Kumamoto plain area excced the maximum permissible limit of Japan drinking water quality standard (10 μg/L). In the reducing groundwater, As(III) constitutes typically more, however; 50% samples dominated with As(III) and 50% samples dominated with As(V) species. High As concentrations occur in anaerobic stagnant groundwaters from this plain area with high dissolved Fe, Mn, moderately dissolved HCO3, PO4, DOC and with very low concentrations of NO3 and SO4 suggesting the reducing condition of subsurface aquifer. Moderately positive correlation between As and dissolved Fe, Mn and strong negative correlation between As(III)/As(V) ratio and V, Cr and U reflect the dependence of As concentration on the reductive process. The wide range of δ34SSO4 values (6.8 to 36.1‰) indicate that sulfur is undergoing redox cycling. Highly enriched values suggesting the process was probably mediated by microbial activity. It also be noted from positive values of sulfur</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120001844','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120001844"><span>Core-Mantle Partitioning of Volatile Siderophile <span class="hlt">Elements</span> and the Origin of Volatile <span class="hlt">Elements</span> in the <span class="hlt">Earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nickodem, K.; Righter, K.; Danielson, L.; Pando, K.; Lee, C.</p> <p>2012-01-01</p> <p>There are currently several hypotheses on the origin of volatile siderophile <span class="hlt">elements</span> in the <span class="hlt">Earth</span>. One hypothesis is that they were added during <span class="hlt">Earth</span> 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 <span class="hlt">elements</span> are depleted in <span class="hlt">Earth</span> 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 <span class="hlt">Earth</span> s core is composed of Fe and some lighter constituents, although the abundances of these lighter <span class="hlt">elements</span> are unknown [4]. Si is one of these potential light <span class="hlt">elements</span> [5] although few studies have analyzed the effect of Si on metal-silicate partitioning, in particular the volatile <span class="hlt">elements</span>. As, In, Ge, and Sb are trace volatile siderophile <span class="hlt">elements</span> which are depleted in the mantle but have yet to be extensively studied. The metal-silicate partition coefficients of these <span class="hlt">elements</span> 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 <span class="hlt">elements</span> 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 <span class="hlt">elements</span> in or-der to gain a greater understanding of the core-mantle separation which occurred during the <span class="hlt">Earth</span> s early stages. The data can then be applied to the origin of volatile <span class="hlt">elements</span> in the <span class="hlt">Earth</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMPP11A1413M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMPP11A1413M"><span>Miocene Coral Skeleton Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Patterns Reflect River Discharge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mertz-Kraus, R.; Brachert, T. C.; Jochum, K. P.</p> <p>2010-12-01</p> <p>Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> (REE) patterns of modern coral skeletons usually reflect the REE composition of ambient seawater which is characterized by heavy REE enriched relative to light REE with NASC (North American Shale Composite) normalized La/Lu ratios of typically <0.4. The REE concentration in coral aragonite is enriched by 3 to 4 orders of magnitude compared to ambient seawater. Here we report trace <span class="hlt">element</span> data including REE of coral skeletons of Late Miocene age (~9 Ma, Tortonian) from Crete (Eastern Mediterranean). Analyses were done using a 213 nm Nd:YAG laser coupled to an <span class="hlt">Element</span>2 ICP-MS along the growth axis of the coral skeletons. The profiles show that Ba/Ca ratios have a seasonally induced pattern with high values around the winter months which are identified by δ18O analyses. REE/Ca ratios co-vary with Ba/Ca ratios. Since the Ba/Ca ratio is a proxy used to monitor river discharge, the co-variation suggests the REE/Ca ratio to be a proxy of comparable quality. NASC-normalized REE patterns of the Tortonian corals have negative Ce anomalies like modern corals. However, the Tortonian corals have REE patterns highly enriched in LREE with (La/Lu)N ratios of 4 to 30 which is 1 to 2 orders of magnitude higher compared to modern corals. Al concentrations are low (<10 ppm) and do not correlate with REE concentrations indicating an insignificant fraction of terrigenous material included in the skeleton. Applying distribution coefficients typical for modern corals, the REE composition of the Tortonian ambient water yields (La/Lu)N of about 2 to 16. This range can be explained by binary mixing of modern Eastern Mediterranean sea surface water ((La/Lu)N=0.35, sea surface salinity (SSS) ~38 ‰) with highly LREE-enriched river water ((La/Lu)N >3, salinity ~0.5 ‰) transporting suspended and colloid phases, also highly enriched, especially in LREE, at a ratio of ~9 (seawater):1 (river water). The river water component is considered because paleoenvironmental</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/4760989','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/4760989"><span>PROCESS FOR SEPARATING AMERICIUM AND CURIUM FROM RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENTS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Baybarz, R.D.; Lloyd, M.H.</p> <p>1963-02-26</p> <p>This invention relates to methods of separating americium and curium values from rare <span class="hlt">earth</span> values. In accordance with the invention americium, curium, and rare <span class="hlt">earth</span> values are sorbed on an anion exchange resin. A major portion of the rare <span class="hlt">earth</span> values are selectively stripped from the resin with a concentrated aqueous solution of lithium chloride, and americium, curium, and a minor portion of rare <span class="hlt">earth</span> values are then stripped from the resin with a dilute aqueous solution of lithium chloride. The americium and curium values are further purified by increasing the concentration of lithium chloride in the solution to at least 8 molar and selectively extracting rare <span class="hlt">earth</span> values from the resulting solution with a monoalkylphosphoric acid. (AEC)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18960776','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18960776"><span>Relative sensitivity of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in spark-source mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Roaldset, E</p> <p>1970-07-01</p> <p>A method for calculating the relative sensitivity factors for the rare <span class="hlt">earth</span> <span class="hlt">elements</span> in geological material is outlined. A close correlation is found between the relative sensitivity factors calculated and isotopic mass and the first ionization potential for the <span class="hlt">elements</span>. The points are grouped in the vicinity of a regression line, which may be used to determine the relative sensitivity factors for all the rare <span class="hlt">earth</span> <span class="hlt">elements</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020068','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020068"><span>Rare <span class="hlt">earth</span> <span class="hlt">element</span> metasomatism in hydrothermal systems: The Willsboro-Lewis wollastonite ores, New York, USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Whitney, P.R.; Olmsted, J.F.</p> <p>1998-01-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">elements</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.140...20C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.140...20C"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> as indicators of hydrothermal processes within the East Scotia subduction zone system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cole, Catherine S.; James, Rachael H.; Connelly, Douglas P.; Hathorne, Ed C.</p> <p>2014-09-01</p> <p>The East Scotia subduction zone, located in the Atlantic sector of the Southern Ocean, hosts a number of hydrothermal sites in both back-arc and island-arc settings. High temperature (>348 °C) 'black smoker' vents have been sampled at three locations along segments E2 and E9 of the East Scotia back-arc spreading ridge, as well as 'white smoker' (<212 °C) and diffuse (<28 °C) hydrothermal fluids from within the caldera of the Kemp submarine volcano. The composition of the endmember fluids (Mg = 0 mmol/kg) is markedly different, with pH ranging from <1 to 3.4, [Cl-] from ∼90 to 536 mM, [H2S] from 6.7 to ∼200 mM and [F-] from 35 to ∼1000 μM. All of the vent sites are basalt- to basaltic andesite-hosted, providing an ideal opportunity for investigating the geochemical controls on rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) behaviour. Endmember hydrothermal fluids from E2 and E9 have total REE concentrations ranging from 7.3 to 123 nmol/kg, and chondrite-normalised distribution patterns are either light REE-enriched (LaCN/YbCN = 12.8-30.0) with a positive europium anomaly (EuCN/Eu∗CN = 3.45-59.5), or mid REE-enriched (LaCN/NdCN = 0.61) with a negative Eu anomaly (EuCN/Eu∗CN = 0.59). By contrast, fluids from the Kemp Caldera have almost flat REE patterns (LaCN/YbCN = 2.1-2.2; EuCN/Eu∗CN = 1.2-2.2). We demonstrate that the REE <span class="hlt">geochemistry</span> of fluids from the East Scotia back-arc spreading ridge is variably influenced by ion exchange with host minerals, phase separation, competitive complexation with ligands, and anhydrite deposition, whereas fluids from the Kemp submarine volcano are also affected by the injection of magmatic volatiles which enhances the solubility of all the REEs. We also show that the REE patterns of anhydrite deposits from Kemp differ from those of the present-day fluids, potentially providing critical information about the nature of hydrothermal activity in the past, where access to hydrothermal fluids is precluded.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUSM.B41A..02R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSM.B41A..02R"><span>Rare <span class="hlt">Earth</span> <span class="hlt">elements</span> as sediment tracers in Mangrove ecosystems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramanathan, A. L.; Swathi, S.</p> <p>2013-05-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> have been widely used as geochemical source fingerprints of rocks and sediments to study processes involving cosmo-chemistry, igneous petrology, tectonic setting and for investigations of water-rock interactions and weathering processes including transport of weathering products to the oceans.Many studies have addressed the use of REEs in investigating the environmental impact of human activity and demonstrated that the REE natural distribution in sediment from densely industrialised and populated regions can be altered by anthropogenic influences.The coastal wetlands like Mangroves are ultimate sinks for all the material derived from the terrestrial and marine environment.The high productivity and low ratio of sediment respiration to net primary production gives mangrove sediments the potential for long-term sequestration of these pollutants/metals before reaching the coastal ocean. Geochemical study of REE in these sedimentary systems is useful for determining the nature of the biogeochemical processes. In particular, REE show a great sensitivity to pH changes, redox conditions and adsorption/ desorption reactions. So, they may be used as markers of discharge provenance, weathering processes, changes in environmental conditions in the water and sediments of Mangrove/wetland systems. Our study aims to establish the abundance, distribution and enrichment of REEs to track the sediment sources and biogeochemical processes occurring in the mangrove environment.Core sediments were collected from the different environmental settings within the Pichavaram mangrove area.Higher REE concentration in Pichavaram sediments indicated greater input from sources like terrestrial weathering and anthropogenic activities which in turn are affected by saline mixing and dynamic physico-chemical processes occurring in the mangrove environment. REE enrichment order was attributed to the alkaline pH (7-8.5) and reducing conditions prevailing in the mangrove</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.B33A1150P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.B33A1150P"><span>Modelling of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Complexation With Humic Acid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pourret, O.; Davranche, M.; Gruau, G.; Dia, A.</p> <p>2006-12-01</p> <p>The binding of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) to humic acid (HA) was studied by combining Ultrafiltration and ICP- MS techniques. REE-HA complexation experiments were performed at various pH conditions (ranging from 2 to 10.5) using a standard batch equilibration method. Results show that the amount of REE bound to HA strongly increase with increasing pH. Moreover, a Middle REE (MREE) downward concavity is evidenced by REE distribution patterns at acidic pH. Modelling of the experimental data using Humic Ion Binding Model VI provided a set of log KMA values (i.e. the REE-HA complexation constants specific to Model VI) for the entire REE series. The log KMA pattern obtained displays a MREE downward concavity. Log KMA values range from 2.42 to 2.79. These binding constants are in good agreement with the few existing datasets quantifying the binding of REE with humic substances except a recently published study which evidence a lanthanide contraction effect (i.e. continuous increase of the constant from La to Lu). The MREE downward concavity displayed by REE-HA complexation pattern determined in this study compares well with results from REE-fulvic acid (FA) and REE-acetic acid complexation studies. This similarity in the REE complexation pattern shapes suggests that carboxylic groups are the main binding sites of REE in HA. This conclusion is further supported by a detailed review of published studies for natural, organic-rich, river- and ground-waters which show no evidence of a lanthanide contraction effect in REE pattern shape. Finally, application of Model VI using the new, experimentally determined log KMA values to World Average River Water confirms earlier suggestions that REE occur predominantly as organic complexes (> 60 %) in the pH range between 5-5.5 and 7-8.5 (i.e. in circumneutral pH waters). The only significant difference as compared to earlier model predictions made using estimated log KMA values is that the experimentally determined log KMA values</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.115...46G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.115...46G"><span>Isotopic and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of alkalic-mafic-ultramafic-carbonatitic complexes and flood basalts in NE India: Origin in a heterogeneous Kerguelen plume</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghatak, Arundhuti; Basu, Asish R.</p> <p>2013-08-01</p> <p>The Archean East Indian cratonic margin was affected by the Kerguelen plume (KP) ˜117 Ma, causing flood-basalt eruptions of the Rajmahal-Bengal-Sylhet Traps (RBST). The RBST cover ˜one million km2 in and around the Bengal Basin as alkalic-ultrabasic intrusives in the west and Sikkim in the north, and Sylhet basalts and alkalic-carbonatitic-ultramafic complexes in the Shillong plateau - Mikir hills farther east of the Rajmahal-Bengal Traps. We provide new Nd-Sr-Pb-isotopic and trace <span class="hlt">element</span> data on 21 unreported discrete lava flows of the Rajmahal Traps, 56 alkalic-carbonatitic-mafic-ultramafic rocks from four alkalic complexes, and three dikes from the Gondwana Bokaro coalfields, all belonging to the RBST. The data allow geochemical correlation of the RBST with some contemporaneous Kerguelen Plateau basalts and KP-related volcanics in the southern Indian Ocean. Specifically, the new data show similarity with previous data of Rajmahal group I-II basalts, Sylhet Traps, Bunbury basalts, and lavas from the southern Kerguelen Plateau, indicating a relatively primitive KP source, estimated as: ɛNd(I) = +2, 87Sr/86Sr(I) = 0.7046, with a nearly flat time-integrated rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) pattern. We model the origin of the uncontaminated RBST basalts by ˜18% batch melting with a 2× chondritic KP source in the spinel-peridotite stability depths of 60-70 km in the mantle. The new geochemical data similar to the Rajmahal group II basalts indicate a light REE enriched average source at ɛNd(I) = -5, 87Sr/86Sr(I) = 0.7069. Our geochemical modeling indicates these lavas assimilated granulites of the Eastern Ghats, reducing the thickness of the continental Indian lithosphere. Lack of an asthenospheric MORB component in the RBST province is indicated by various trace <span class="hlt">element</span> ratios as well as the Nd-Sr isotopic ratios. Three alkalic complexes, Sung, Samchampi, and Barpung in NE India, and one in Sikkim to the north are of two groups: carbonatites, pyroxenites, lamproites</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015CoMP..170...11S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CoMP..170...11S"><span>Genesis of the central zone of the Nolans Bore rare <span class="hlt">earth</span> <span class="hlt">element</span> deposit, Northern Territory, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schoneveld, Louise; Spandler, Carl; Hussey, Kelvin</p> <p>2015-08-01</p> <p>The Nolans Bore rare <span class="hlt">earth</span> <span class="hlt">element</span> (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 <span class="hlt">geochemistry</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010754','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010754"><span>Biogeochemistry of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> with particular reference to hickory trees</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Robinson, W.O.; Bastron, H.; Murata, K.J.</p> <p>1958-01-01</p> <p>Hickory trees concentrate the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in their leaves to a phenomenal degree and may contain as much as 2300 p.p.m. of total rare <span class="hlt">earths</span> based on the dry weight of the leaves. The average proportions of the individual <span class="hlt">elements</span> (atomic percent of the total rare-<span class="hlt">earth</span> <span class="hlt">elements</span>) 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-<span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earths</span> appreciably. The variation of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">element</span> 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-<span class="hlt">earth</span> <span class="hlt">elements</span> 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-<span class="hlt">earth</span> <span class="hlt">elements</span> that do not undergo such a change in valence. A few parts per billion of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> have been detected in two samples of ground water. ?? 1958.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2012/1016/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2012/1016/"><span>Review of rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in oil shales of the Eocene Green River Formation</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Birdwell, Justin E.</p> <p>2012-01-01</p> <p>Concentrations of the lanthanide series or rare <span class="hlt">earth</span> <span class="hlt">elements</span> and yttrium were determined for lacustrine oil shale samples from the Eocene Green River Formation in the Piceance Basin of Colorado and the Uinta Basin of Utah. Unprocessed oil shale, post-pyrolysis (spent) shale, and leached shale samples were examined to determine if oil-shale processing to generate oil or the remediation of retorted shale affects rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations. Results for unprocessed Green River oil shale samples were compared to data published in the literature on reference materials, such as chondritic meteorites, the North American shale composite, marine oil shale samples from two sites in northern Tibet, and mined rare <span class="hlt">earth</span> <span class="hlt">element</span> ores from the United States and China. The Green River oil shales had lower rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations (66.3 to 141.3 micrograms per gram, μg g-1) than are typical of material in the upper crust (approximately 170 μg g-1) and were also lower in rare <span class="hlt">earth</span> <span class="hlt">elements</span> relative to the North American shale composite (approximately 165 μg g-1). Adjusting for dilution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> by organic matter does not account for the total difference between the oil shales and other crustal rocks. Europium anomalies for Green River oil shales from the Piceance Basin were slightly lower than those reported for the North American shale composite and upper crust. When compared to ores currently mined for rare <span class="hlt">earth</span> <span class="hlt">elements</span>, the concentrations in Green River oil shales are several orders of magnitude lower. Retorting Green River oil shales led to a slight enrichment of rare <span class="hlt">earth</span> <span class="hlt">elements</span> due to removal of organic matter. When concentrations in spent and leached samples were normalized to an original rock basis, concentrations were comparable to those of the raw shale, indicating that rare <span class="hlt">earth</span> <span class="hlt">elements</span> are conserved in processed oil shales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=251706&keyword=electronics&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78720393&CFTOKEN=72639854','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=251706&keyword=electronics&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78720393&CFTOKEN=72639854"><span>RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENTS</span>: A REVIEW OF PRODUCTION, PROCESSING, RECYCLING, AND ASSOCIATED ENVIRONMENTAL ISSUES</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are a group of 15 chemical <span class="hlt">elements</span> in the periodic table, specifically the lanthanides. Two other <span class="hlt">elements</span>, scandium and yttrium, have a similar physiochemistry to the lanthanides, are commonly found in the same mineral assemblages, and are often refe...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.140..177F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.140..177F"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> and neodymium isotopes in sedimentary organic matter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure</p> <p>2014-09-01</p> <p>We report rare <span class="hlt">earth</span> <span class="hlt">element</span> (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 ΣREE = 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 εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980002855','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980002855"><span>Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Partition Coefficients from Enstatite/Melt Synthesis Experiments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schwandt, Craig S.; McKay, Gordon A.</p> <p>1997-01-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">element</span> concentrations were measured in both the basaltic glass and the enstatite. Rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in the glass were determined by electron microprobe analysis with uncertainties less than two percent relative. Rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in enstatite were determined by secondary ion mass spectrometry with uncertainties less than five percent relative. The resulting rare <span class="hlt">earth</span> <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140003556','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140003556"><span>Core-Mantle Partitioning of Volatile <span class="hlt">Elements</span> and the Origin of Volatile <span class="hlt">Elements</span> in <span class="hlt">Earth</span> and Moon</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, Kevin; Pando, K.; Danielson, L.; Nickodem, K.</p> <p>2014-01-01</p> <p>Depletions of volatile siderophile <span class="hlt">elements</span> (VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd) in mantles of <span class="hlt">Earth</span> and Moon, constrain the origin of volatile <span class="hlt">elements</span> in these bodies, and the overall depletion of volatile <span class="hlt">elements</span> in Moon relative to <span class="hlt">Earth</span>. A satisfactory explanation has remained elusive [1,2]. We examine the depletions of VSE in <span class="hlt">Earth</span> and Moon and quantify the amount of depletion due to core formation and volatility of potential building blocks. We calculate the composition of the <span class="hlt">Earth</span>'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 <span class="hlt">element</span> content of <span class="hlt">Earth</span>'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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990STIN...9126421W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990STIN...9126421W"><span>Input impedance and gain of monopole <span class="hlt">elements</span> with disk ground planes on flat <span class="hlt">earth</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weiner, M. M.</p> <p>1990-12-01</p> <p>This paper extends previously reported results for a quarterwave monopole <span class="hlt">element</span> on a disk ground plane in free space to the case where the disk ground plane rests on flat <span class="hlt">earth</span>. Numerical results are obtained by utilizing Richmond's method of moments computer program for disk ground planes over flat <span class="hlt">earth</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGC51F1166B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGC51F1166B"><span>Trace <span class="hlt">Element</span> Inputs to the Upper West Pacific from Nd Isotopes and Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Behrens, M. K.; Pahnke, K.; Schnetger, B.; Brumsack, H. J.</p> <p>2015-12-01</p> <p>Neodymium isotopes (143Nd/144Nd, expressed as ɛNd) and rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations in the ocean trace water mass transport and margin-seawater exchange processes. The distinct ɛNd and REE signatures of the lithogenic components of margin sediments of the West Pacific allow characterization of trace <span class="hlt">element</span> inputs to the Pacific Ocean. We present dissolved ɛNdand REE concentrations from twelve vertical profiles of a transect from South Korea to Fiji. Near South Korea, surface waters are marked by unradiogenic ɛNd (as low as -7.3), high REE concentrations (e.g., Nd = 15.3 pmol/kg) and low salinity. Towards the open ocean, these parameters gradually change towards typical Pacific open ocean values (ɛNd = -3.3, [Nd] = 5.55 pmol/kg). Subsurface waters show REE depletions, followed by the typical REE increase with increasing water depth. These distributions indicate trace <span class="hlt">element</span> input near South Korea and enhanced subsurface scavenging, as indicated by strong heavy REE to light REE fractionation. In the tropical West Pacific (10°N-15°S), high surface and subsurface water ɛNd values (+0.7) and positive Eu anomalies trace the influence of volcanic islands. Yet, absolute REE concentrations are extremely low at these depths (e.g., Nd = 2.77 pmol/kg). Using shale-normalized Nd/Er and Ho/Dy ratios, that show a much stronger surface to subsurface decrease in coastal waters compared to the open ocean, we suggest enhanced scavenging in this area. Eastward flowing intermediate waters (NPIW, AAIW) have ɛNd values up to +1.9 (NPIW) and +3.7 (AAIW) higher than those entering the tropical West Pacific from north and south, respectively. Modified ɛNd at intermediate depths and no change in REE patterns suggest that boundary exchange along volcanic island margins modifies the seawater ɛNd without changing the REE budget.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1261978','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1261978"><span>Experimental Parameters Affecting Stripping of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from Loaded Sorptive Media in Simulated Geothermal Brines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dean Stull</p> <p>2016-05-24</p> <p>Experimental results from several studies exploring the impact of pH and acid volume on the stripping of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) loaded onto ligand-based media via an active column. The REEs in this experiment were loaded onto the media through exposure to a simulated geothermal brine with known mineral concentrations. The data include the experiment results, rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations, and the experimental parameters varied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1004760','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1004760"><span>(BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2016-02-02</p> <p>AFRL-AFOSR-VA-TR-2016-0091 (BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> George...2012 – 31/10/2015 4. TITLE AND SUBTITLE (BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span>... Science and Eng., Raleigh, NC (Profs. Justin Schwartz and Carl C. Koch). Their team performed all manufacturing and experimental measurements. 14</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V33G..01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V33G..01S"><span>Investigation of Chemical and Physical Changes to Bioapatite During Fossilization Using Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span>, Infrared Spectroscopy and Stable Isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suarez, C. A.; Kohn, M. J.</p> <p>2013-12-01</p> <p>Bioapatite in the form of vertebrate bone can be used for a wide variety of paleo-proxies, from determination of ancient diet to the isotopic composition of meteoric water. Bioapatite alteration during diagenesis is a constant barrier to the use of fossil bone as a paleo-proxy. To elucidate the physical and chemical alteration of bone apatite during fossilization, we analyzed an assortment of fossil bones of different ages for trace <span class="hlt">elements</span>, using LA-ICP-MS, stable isotopes, and reflected IR spectroscopy. One set of fossil bones from the Pleistocene of Idaho show a diffusion recrystallization profile, however, rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) profiles indicate diffusion adsorption. This suggests that REE diffusion is controlled by changing (namely decreasing) boundary conditions (i.e. decreasing concentration of REE in surrounding pore fluids). Reflected IR analysis along this concentration profile reveal that areas high in U have lost type A carbonate from the crystal structure in addition to water and organics. Stable isotopic analysis of carbon and oxygen will determine what, if any, change in the isotopic composition of the carbonate component of apatite has occurred do to the diffusion and recrystallization process. Analysis of much older bone from the Cretaceous of China reveal shallow REE and U concentration profiles and very uniform reflected IR spectra with a significant loss of type A carbonate throughout the entire bone cortex. Analysis of stable isotopes through the bone cortex will be compared to the stable isotopes collected from the Pleistocene of Idaho.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/4836837','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/4836837"><span>SEPARATION OF TRANSURANIC <span class="hlt">ELEMENTS</span> FROM RARE <span class="hlt">EARTH</span> COMPOUNDS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Kohman, T.P.</p> <p>1961-11-21</p> <p>A process of separating neptunium and plutonium values from rare <span class="hlt">earths</span> and alkaline <span class="hlt">earth</span> fission products present on a solid mixed actinide carrier (Th or U(IV) oxalate or fluoride) --fission product carrier (LaF/sub 3/, CeF/sub 3/, SrF/sub 2/, CaF/sub 2/, YF/sub 3/, La oxalate, cerous oxalate, Sr oxalate, Ca oxalate or Y oxalate) by extraction of the actinides at elevated temperature with a solution of ammonium fluoride and/or ammonium oxalate is described. Separation of the fission-product-containing carriers from the actinide solution formed and precipitation of the neptunium and plutonium from the solution with mineral acid are also accomplished. (AEC)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA547354','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA547354"><span>An Integrated Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Supply Chain Strategy</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2011-02-24</p> <p>Disruption in the global supply of rare <span class="hlt">earths</span> poses a significant concern for America‘s energy security and clean energy objectives, its future defense...World Trade Organization rules by limiting clean energy imports, while incentivizing clean energy exports.54 If accurate, this speculation supports...resource scarcity and secure our supply chains. The NSS further declares the U.S. ―has a window of opportunity to lead in the development of clean energy technology</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017IJEaS.106..617L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017IJEaS.106..617L"><span><span class="hlt">Elemental</span> and Sr-Nd isotopic <span class="hlt">geochemistry</span> of Permian Emeishan flood basalts in Zhaotong, Yunnan Province, SW China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Juan; Zhong, Hong; Zhu, Wei-Guang; Bai, Zhong-Jie; Hu, Wen-Jun</p> <p>2017-03-01</p> <p>This study presents new whole-rock <span class="hlt">elemental</span> and isotopic data for the basalts from the Zhaotong area, located in the intermediate zone of the 260 Ma Emeishan large igneous province (ELIP). The Zhaotong basalts belong to high-Ti series with TiO2 from 2.93 to 5.26 % and Ti/Y from 519 to 974. The parental magma was subjected to minor crustal contamination as indicated by slight Nb-Ta depletion (Nb/La: 0.72-1.10). Meanwhile, the relatively invariable Sr-Nd isotopes (ɛNd( t): -0.74 to +2.86, mostly +1.10 to +2.86; (87Sr/86Sr)i: 0.7050-0.7072) and the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE) enrichment (La/Yb: 10.3-19.1) of the basalts prefer a mantle plume origin. A garnet-dominated peridotite mantle source was further suggested on the basis of the REE distribution patterns and high Sm/Yb and high La/Yb ratios. This study further confirms the geochemical zoning of the high-Ti basalts in the ELIP, which is in accordance with both the spatial distribution and the thickness of the basalts. The high-Ti basalts in the intermediate and outer zones of ELIP (e.g., Zhaotong and Guizhou) share similar Sr-Nd isotopic and <span class="hlt">elemental</span> compositions, suggesting that they originated directly from the Emeishan mantle plume. By contrast, the high-Ti basalts in the inner zone (e.g., Longzhoushan and Binchuan) have variable compositions, indicating a rather heterogeneous mantle source possibly involved with subcontinental lithospheric mantle (SCLM) components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJEaS.tmp...40L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJEaS.tmp...40L"><span><span class="hlt">Elemental</span> and Sr-Nd isotopic <span class="hlt">geochemistry</span> of Permian Emeishan flood basalts in Zhaotong, Yunnan Province, SW China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Juan; Zhong, Hong; Zhu, Wei-Guang; Bai, Zhong-Jie; Hu, Wen-Jun</p> <p>2016-05-01</p> <p>This study presents new whole-rock <span class="hlt">elemental</span> and isotopic data for the basalts from the Zhaotong area, located in the intermediate zone of the ~260 Ma Emeishan large igneous province (ELIP). The Zhaotong basalts belong to high-Ti series with TiO2 from 2.93 to 5.26 % and Ti/Y from 519 to 974. The parental magma was subjected to minor crustal contamination as indicated by slight Nb-Ta depletion (Nb/La: 0.72-1.10). Meanwhile, the relatively invariable Sr-Nd isotopes (ɛNd(t): -0.74 to +2.86, mostly +1.10 to +2.86; (87Sr/86Sr)i: 0.7050-0.7072) and the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE) enrichment (La/Yb: 10.3-19.1) of the basalts prefer a mantle plume origin. A garnet-dominated peridotite mantle source was further suggested on the basis of the REE distribution patterns and high Sm/Yb and high La/Yb ratios. This study further confirms the geochemical zoning of the high-Ti basalts in the ELIP, which is in accordance with both the spatial distribution and the thickness of the basalts. The high-Ti basalts in the intermediate and outer zones of ELIP (e.g., Zhaotong and Guizhou) share similar Sr-Nd isotopic and <span class="hlt">elemental</span> compositions, suggesting that they originated directly from the Emeishan mantle plume. By contrast, the high-Ti basalts in the inner zone (e.g., Longzhoushan and Binchuan) have variable compositions, indicating a rather heterogeneous mantle source possibly involved with subcontinental lithospheric mantle (SCLM) components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1818375R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1818375R"><span>The Role Of Mineralogy And <span class="hlt">Geochemistry</span> In The Understanding Of The Trace <span class="hlt">Elements</span> Soil Pollution And Remediation. Cases Study In Mining Areas Of Andalucia (South Spain).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Romero, Antonio; González, Isabel; Galán, Emilio</p> <p>2016-04-01</p> <p>Geochemical and mineralogical studies of soils potentially polluted by trace <span class="hlt">elements</span> are basic to find the source of pollution, to understand the behaviour of the contaminants in the environment and, finally, to propose remediation and reclamation actions. This work reviews the role of the Mineralogy and <span class="hlt">Geochemistry</span> to assess the hazard of soil contamination, focusing on several studies carried out in the Andalusian Community (South Spain). To assess the degree of contamination, regional and local geochemical baselines should be established in order to distinguish the geogenic from the anthropogenic contribution, particularly in mining areas where both sources overlap. In these areas, mineralogical studies of the primary phases releasing contaminant <span class="hlt">elements</span> and the secondary phases precipitating will help to understand the processes affecting the contamination. Agricultural activities are also important sources of trace <span class="hlt">elements</span> into soils. Several examples show they may be relevant even in mining areas. The metals reaching the soil tend to be accumulated, but they can mobilize under certain physical-chemical environments. The hazard of the contamination will depend on the availability of the trace <span class="hlt">elements</span>, the adsorption processes and the stability of mineral phases storing the trace <span class="hlt">elements</span>. Several results show that the availability of trace <span class="hlt">elements</span> is usually higher in contaminated sites than in geogenic soils, regardless the total concentration. Mineralogical and geochemical studies are then interesting to understand the processes affecting the contamination, as well as to prevent the hazard to the population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAESc.105..300S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAESc.105..300S"><span>Platinum Group <span class="hlt">Elements</span> (PGE) <span class="hlt">geochemistry</span> of komatiites and boninites from Dharwar Craton, India: Implications for mantle melting processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saha, Abhishek; Manikyamba, C.; Santosh, M.; Ganguly, Sohini; Khelen, Arubam C.; Subramanyam, K. S. V.</p> <p>2015-06-01</p> <p>High MgO volcanic rocks having elevated concentrations of Ni and Cr are potential hosts for platinum group <span class="hlt">elements</span> (PGE) owing to their primitive mantle origin and eruption at high temperatures. Though their higher PGE abundance is economically significant in mineral exploration studies, their lower concentrations are also valuable geochemical tools to evaluate petrogenetic processes. In this paper an attempt has been made to evaluate the PGE <span class="hlt">geochemistry</span> of high MgO volcanic rocks from two greenstone belts of western and eastern Dharwar Craton and to discuss different mantle processes operative at diverse geodynamic settings during the Neoarchean time. The Bababudan greenstone belt of western and Gadwal greenstone belt of eastern Dharwar Cratons are dominantly composed of high MgO volcanic rocks which, based on distinct geochemical characteristics, have been identified as komatiites and boninites respectively. The Bababudan komatiites are essentially composed of olivine and clinopyroxene with rare plagioclase tending towards komatiitic basalts. The Gadwal boninites contain clinopyroxene, recrystallized hornblende with minor orthopyroxene, plagioclase and sulphide minerals. The Bababudan komatiites are Al-undepleted type (Al2O3/TiO2 = 23-59) with distinctly high MgO (27.4-35.8 wt.%), Ni (509-1066 ppm) and Cr (136-3036 ppm) contents. These rocks have low ΣPGE (9-42 ppb) contents with 0.2-2.4 ppb Iridium (Ir), 0.2-1.4 ppb Osmium (Os) and 0.4-4.4 ppb Ruthenium (Ru) among Iridium group PGE (IPGE); and 1.4-16.2 ppb Platinum (Pt), 2.8-19 ppb Palladium (Pd) and 0.2-9.8 ppb Rhodium (Rh) among Platinum group PGE (PPGE). The Gadwal boninites are high-Ca boninites with CaO/Al2O3 ratios varying between 0.8 and 1.0, with 12-24 wt.% MgO, 821-1168 ppm Ni and 2307-2765 ppm Cr. They show higher concentration of total PGE (82-207 ppb) with Pt concentration ranging from 13 to 19 ppb, Pd between 65 and 180 ppb and Rh in the range of 1.4-3 ppb compared to the Bababudan komatiites. Ir</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25089667','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25089667"><span>Rare <span class="hlt">earth</span> <span class="hlt">element</span> recycling from waste nickel-metal hydride batteries.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Xiuli; Zhang, Junwei; Fang, Xihui</p> <p>2014-08-30</p> <p>With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare <span class="hlt">earth</span> <span class="hlt">elements</span>, the recycling of rare <span class="hlt">earth</span> <span class="hlt">elements</span> is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. A maximum rare <span class="hlt">earth</span> <span class="hlt">elements</span> recovery of 95.16% was achieved at optimal leaching conditions of 70°C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, -74μm particle size, and 100min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1-(1-x)(1/3)=A/ρr0[HCl](0.64)exp-439,8008.314Tt. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare <span class="hlt">earth</span> <span class="hlt">element</span> oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810°C, a final product of 99% pure rare <span class="hlt">earth</span> oxides was obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24835593','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24835593"><span>Experimental productivity rate optimization of rare <span class="hlt">earth</span> <span class="hlt">element</span> separation through preparative solid phase extraction chromatography.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Knutson, Hans-Kristian; Max-Hansen, Mark; Jönsson, Christian; Borg, Niklas; Nilsson, Bernt</p> <p>2014-06-27</p> <p>Separating individual rare <span class="hlt">earth</span> <span class="hlt">elements</span> from a complex mixture with several <span class="hlt">elements</span> is difficult and this is emphasized for the middle <span class="hlt">elements</span>: Samarium, Europium and Gadolinium. In this study we have accomplished an overloaded one-step separation of these rare <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">element</span> 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 <span class="hlt">element</span>, 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)).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17218521','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17218521"><span>Highly siderophile <span class="hlt">element</span> constraints on accretion and differentiation of the <span class="hlt">Earth</span>-Moon system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Day, James M D; Pearson, D Graham; Taylor, Lawrence A</p> <p>2007-01-12</p> <p>A new combined rhenium-osmium- and platinum-group <span class="hlt">element</span> data set for basalts from the Moon establishes that the basalts have uniformly low abundances of highly siderophile <span class="hlt">elements</span>. The data set indicates a lunar mantle with long-term, chondritic, highly siderophile <span class="hlt">element</span> ratios, but with absolute abundances that are over 20 times lower than those in <span class="hlt">Earth</span>'s mantle. The results are consistent with silicate-metal equilibrium during a giant impact and core formation in both bodies, followed by post-core-formation late accretion that replenished their mantles with highly siderophile <span class="hlt">elements</span>. The lunar mantle experienced late accretion that was similar in composition to that of <span class="hlt">Earth</span> but volumetrically less than (approximately 0.02% lunar mass) and terminated earlier than for <span class="hlt">Earth</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6292388','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6292388"><span>Vanadium oxide bronzes containing rare-<span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Volkov, V.L.; Zubkov, V.G.; Fedyukov, A.S.; Zainulin, Yu.G.</p> <p>1988-05-01</p> <p>We attempted to make phases having the general formula Ln/sub x/V/sub 2/O/sub 5/ (Ln = La, Eu, Yb) without success; the specimens usually consisted of three phases: the rare-<span class="hlt">earth</span> orthovanadate LnVO/sub 4/, vanadium(V) oxide, and VO/sub 2/. To shift the process to give Ln/sub x/V/sub 2/O/sub 5/, heat treatment was applied to mixtures of the initial high-purity substances. The x-ray patterns were recorded with a DRON-UM1 apparatus with Cr K..cap alpha.. radiation and were processed by the Poroshok program. The IR spectra were recorded with UR-20 spectrometer with oil mulls.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26222789','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26222789"><span>Mobile DNA <span class="hlt">Elements</span>: The Seeds of Organic Complexity on <span class="hlt">Earth</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Habibi, Laleh; Pedram, Mehrdad; AmirPhirozy, Akbar; Bonyadi, Khadijeh</p> <p>2015-10-01</p> <p>Mobile DNA or transposable <span class="hlt">elements</span> (TEs) are genomic sequences capable of moving themselves independently into different parts of the genome. Viral invasion of eukaryotic genomes is assumed to be the main source of TEs. Selfish transposition of these <span class="hlt">elements</span> could be a serious threat to the host cell, as they can insert themselves into the middle of coding genes and/or induce genomic instability. In response, through millions of years of evolution, cells have come up with various mechanisms such as genomic imprinting, DNA methylation, heterochromatin formation, and RNA interference to deactivate them. Interestingly, these processes have also greatly contributed to important cellular functions involved in cell differentiation, development, and differential gene expression. Propagation of TE copies during the course of evolution have resulted in increasing the genome size and providing proper space and flexibility in shaping the genome by creating new genes and establishing essential cellular structures such as heterochromatin, centromere, and telomeres. Yet, these <span class="hlt">elements</span> are mostly labeled for playing a role in pathogenesis of human diseases. Here, we attempt to introduce TEs as factors necessary for making us human rather than just selfish sequences or obligatory guests invading our DNA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70035639','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70035639"><span>U-Pb SHRIMP geochronology and trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of coesite-bearing zircons, North-East Greenland Caledonides</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McClelland, W.C.; Power, S.E.; Gilotti, J.A.; Mazdab, F.K.; Wopenka, B.</p> <p>2006-01-01</p> <p>Obtaining reliable estimates for the timing of eclogite-facies metamorphism is critical to establishing models for the formation and exhumation of high-pressure and ultrahigh-pressure (UHP) metamorphic terranes in collisional orogens. The presence of pressure-dependent phases, such as coesite, included in metamorphic zircon is generally regarded as evidence that zircon growth occurred at UHP conditions and, ifdated, should provide the necessary timing information. We report U-Pb sensitive high-resolution ion microprobe (SHRIMP) ages and trace-<span class="hlt">element</span> SHRIMP data from coesite-bearing zircon suites formed during UHP metamorphism in the North- East Greenland Caledonides. Kyanite eclogite and quartzofeldspathic host gneiss samples from an island in J??kelbugt (78??00'N, 18??04'W) contained subspherical zircons with well-defined domains in cathodoluminescence (CL) images. The presence of coesite is confirmed by Raman spectroscopy in six zircons from four samples. Additional components of the eclogite-facies inclusion suite include kyanite, omphacite, garnet, and rutile. The trace-<span class="hlt">element</span> signatures in core domains reflect modification of igneous protolith zircon. Rim signatures show flat heavy rare <span class="hlt">earth</span> <span class="hlt">element</span> (HREE) patterns that are characteristic of eclogite-facies zircon. The kyanite eclogites generally lack a Eu anomaly, whereas a negative Eu anomaly persists in all domains of the host gneiss. The 207Pb- corrected 206Pb/238U ages range from 330 to 390 Ma for the host gneiss and 330-370 Ma for the kyanite eclogite. Weighted mean 206Pb/238U ages for coesite-bearing domains vary from 364 ?? 8 Ma for the host gneiss to 350 ?? 4 Ma for kyanite eclogite. The combined U-Pb and REE data interpreted in conjunction with observed CL domains and inclusion suites suggest that (1) Caledonian metamorphic zircon formed by both new zircon growth and recrystallization, (2) UHP metamorphism occurred near the end of the Caledonian collision, and (3) the 30-50m.y. span of ages</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26978935','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26978935"><span>[Application of ICP-MS to Detect Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Three Economic Macroalgaes in China].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Yan-fang; Shang, De-rong; Zhai, Yu-xiu; Ning, Jin-song; Ding, Hai-yan; Sheng, Xiao-feng</p> <p>2015-11-01</p> <p>In order to investigate the content and distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in main economic macroalgaes in our country, fifteen rare <span class="hlt">earth</span> <span class="hlt">elements</span> in three economic macroalgaes (including 30 samples of kelp, 30 samples of laver and 15 samples of Enteromorpha) were detected using ICP-MS method. Results showed that the total content of REE in different species of macroalgaes was different. The highest total content of REE was in Enteromorpha (16,012.0 ng · g⁻¹), while in kelp and laver, the total REE was similar for two macroalgaes (3887.4 and 4318.1 ng · g⁻¹ respectively). The content of fifteen rare <span class="hlt">earth</span> <span class="hlt">elements</span> in kelp ranged from 7.9 to 1496.4 ng · g⁻¹; in laver, it ranged from 8.2 to 1836.6 ng · g⁻¹. For Enteromorpha, the concentration of 15 rare <span class="hlt">earth</span> <span class="hlt">elements</span> were between 19.2 and 6014.5 ng · g⁻¹. In addition, the content and distribution of different rare <span class="hlt">earth</span> <span class="hlt">elements</span> in different macroalgaes was also different. For kelp, the highest content of REE was Ce (1 496.4 ng · g⁻¹), and the second was La (689.1 ng · g⁻¹). For laver, the highest was Y (1836.6 ng · g⁻¹), and the second was Ce (682.2 ng · g⁻¹). For Enteromorpha, the highest was Ce (6014.5 ng · g⁻¹), and the second was La (2902.9 ng · g⁻¹). Present results also showed that three macroalgaes accumulated the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> much more than the high rare <span class="hlt">earth</span> <span class="hlt">elements</span>. The light rare <span class="hlt">earth</span> <span class="hlt">elements</span> occupied 90.9%, 87.3% and 91.1% for kelp, laver and Enteromorpha respectively. The result that the Enteromorpha had high content of rare <span class="hlt">earth</span> <span class="hlt">elements</span> could provide important support for opening new research directions for the utilization of Enteromorpha.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12663949','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12663949"><span>Research of the entry of rare <span class="hlt">earth</span> <span class="hlt">elements</span> Eu3+ and La3+ into plant cell.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gao, Yongsheng; Zeng, Fuli; Yi, An; Ping, Shi; Jing, Lanhua</p> <p>2003-03-01</p> <p>Whether rare <span class="hlt">earth</span> <span class="hlt">elements</span> can enter into plant cells remains controversial. This article discusses the ultracellular structural localization of lanthanum (La(3+)) and europium (Eu(3+)) in the intact plant cells fed by rare <span class="hlt">earth</span> <span class="hlt">elements</span> Eu(3+) and La(3+). Eu-TTA fluorescence analysis of the plasmalemma, cytoplast, and mitochondria showed that Eu(3+) fluorescence intensities in such structures significantly increased. Eu(3+) can directly enter or be carried by the artificial ion carrier A23187 into plant cells through the calcium ion (Ca(2+)) channel and then partially resume the synthesis of amaranthin in the Amaranthus caudatus growing in the dark. Locations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> La(3+) and Eu(3+) in all kinds of components of cytoplasmatic organelles were determined with transmission electron microscope, scanning electron microscope, and energy-dispersive X-ray microanalysis. The results of energy-dispersive X-ray microanalysis indicated that Eu(3+) and La(3+) can be absorbed into plant cells and bind to the membranes of protoplasm, chloroplast, mitochondrion, cytoplast, and karyon. These results provide experimental evidence that rare <span class="hlt">earth</span> <span class="hlt">elements</span> can be absorbed into plant cells, which would be the basis for interpreting physiological and biochemical effects of rare <span class="hlt">earth</span> <span class="hlt">elements</span> on plant cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730034958&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2527%2527rare%2Bearths%2527%2527','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730034958&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2527%2527rare%2Bearths%2527%2527"><span>Rare <span class="hlt">earths</span> and other trace <span class="hlt">elements</span> in Apollo 14 samples.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Helmke, P. A.; Haskin, L. A.; Korotev, R. L.; Ziege, K. E.</p> <p>1972-01-01</p> <p>REE and other trace <span class="hlt">elements</span> have been determined in igneous rocks 14053, 14072, and 14310, in breccias 14063 and 14313, and in fines 14163. All materials analyzed have typical depletions of Eu except for feldspar fragments from the breccias and igneous fragments from 14063. Igneous rocks 14072 and 14053 have REE concentrations very similar to Apollo 12 basalts; 14310 has the highest REE concentrations yet observed for a large fragment of lunar basalt. The effects of crystallization of a basaltic liquid as a closed system on the concentrations of Sm and Eu in feldspar are considered. Small anorthositic fragments may have originated by simple crystallization from very highly differentiated basalt (KREEP) or by closed-system crystallization in a less differentiated starting material. Application of independent models of igneous differentiation to Sm and Eu in massive anorthosite 15415 and to Sm and Eu in lunar basalts suggests a common starting material with a ratio of concentrations of Sm and Eu about the same as that in chondrites and with concentrations of those <span class="hlt">elements</span> about 15 times enriched over chondrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000040791','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000040791"><span>Geochemical Constraints on Core Formation in the <span class="hlt">Earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, John H.; Drake, Michael J.</p> <p>1986-01-01</p> <p>New experimental data on the partitioning of siderophile and chalcophile <span class="hlt">elements</span> among metallic and silicate phases may be used to constrain hypotheses of core formation in the <span class="hlt">Earth</span>. Three current hypotheses can explain gross features of mantle <span class="hlt">geochemistry</span>, but none predicts siderophile and chalcophile <span class="hlt">element</span> abundances to within a factor of two of observed values. Either our understanding of metal-silicate interactions and/or our understanding of the early <span class="hlt">Earth</span> requires revision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25430011','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25430011"><span>Levels of major and trace <span class="hlt">elements</span>, including rare <span class="hlt">earth</span> <span class="hlt">elements</span>, and ²³⁸U in Croatian tap waters.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fiket, Željka; Rožmarić, Martina; Krmpotić, Matea; Benedik, Ljudmila</p> <p>2015-05-01</p> <p>Concentrations of 46 <span class="hlt">elements</span>, including major, trace, and rare <span class="hlt">earth</span> <span class="hlt">elements</span>, 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 <span class="hlt">elements</span> and (238)U activity concentrations in Croatian tap waters. Obtained concentrations were compared with the Croatian maximum contaminant levels for trace <span class="hlt">elements</span> 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 <span class="hlt">elements</span>, 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 <span class="hlt">earth</span> <span class="hlt">element</span> data, including abundances and fractionation patterns, complemented the characterization and facilitated the interpretation of factors affecting the composition of the analyzed tap waters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.V51D0316P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.V51D0316P"><span>The Toxicological <span class="hlt">Geochemistry</span> of Dusts, Soils, and Other <span class="hlt">Earth</span> Materials: Insights From In Vitro Physiologically-based Geochemical Leach Tests</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Plumlee, G. S.; Ziegler, T. L.; Lamothe, P.; Meeker, G. P.; Sutley, S.</p> <p>2003-12-01</p> <p>Exposure to mineral dusts, soils, and other <span class="hlt">earth</span> materials results in chemical reactions between the materials and different body fluids that include, depending upon the exposure route, lung fluids, gastrointestinal fluids, and perspiration. In vitro physiologically-based geochemical leach tests provide useful insights into these chemical reactions and their potential toxicological implications. We have conducted such leach tests on a variety of <span class="hlt">earth</span> materials, including asbestos, volcanic ash, dusts from dry lake beds, mine wastes, wastes left from the roasting of mercury ores, mineral processing wastes, coal dusts and coal fly ash, various soils, and complex dusts generated by the World Trade Center collapse. Size-fractionated samples of <span class="hlt">earth</span> materials that have been well-characterized mineralogically and chemically are reacted at body temperature (37 C) for periods from 2 hours up to multiple days with various proportions of simulated lung, gastric, intestinal, and/or plasma-based fluids. Results indicate that different <span class="hlt">earth</span> materials may have quite different solubility and dissolution behavior in vivo, depending upon a) the mineralogic makeup of the material, and b) the exposure route. For example, biodurable minerals such as asbestos and volcanic ash particles, whose health effects result because they dissolve very slowly in vivo, bleed off low levels of trace metals into the simulated lung fluids; these include metals such as Fe and Cr that are suspected by health scientists of contributing to the generation of reactive oxygen species and resulting DNA damage in vivo. In contrast, dry lake bed dusts and concrete-rich dusts are highly alkaline and bioreactive, and cause substantial pH increases and other chemical changes in the simulated body fluids. Many of the <span class="hlt">earth</span> materials tested contain a variety of metals that can be quite soluble (bioaccessible), depending upon the material and the simulated body fluid composition. For example, due to their acidic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.H21C0837B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.H21C0837B"><span>Rare <span class="hlt">Earth</span> <span class="hlt">Elemental</span> Signatures in Fungal Fruiting Bodies as Probes into Mineral Breakdown Reactions in Post-glacial Landscapes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bryce, J. G.; Hobbie, E. A.</p> <p>2008-12-01</p> <p>The application of rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) abundances in low temperature <span class="hlt">geochemistry</span> and biogeochemistry has improved our understanding of the cycling of various micro- and macronutrients from the bedrock into terrestrial ecosystems. In many continental rocks, REEs are concentrated in accessory phases such as apatite and monazite. These phosphate mineral phases break down readily and may be especially important nutrient sources, particularly for P and Ca, in recently glaciated terrains. Several studies (e.g., 1-3) have suggested that the presence of ectomycorrhizal (ECM) fungi, due to the organic acids they secrete, may play an especially important role in this weathering process. A field-based experiment implementing mesh bags doped with specific mineral compositions confirmed that ECM fungal tissues do record the REE signatures of the minerals they break down (4). In an effort to understand the relative role different ECM fungi may play in mineral breakdown reactions, we have measured REE abundances in tissues of several ECM fruiting bodies. Our preliminary data include Russula, Suillus Americana, Leccinum and Lactarius ECM fungi from three postglacial landscapes. At a given site, the relative abundance of REEs varies between the different ECM fungi. Interestingly, we found distinctions in tissue La/Ce values at two of the sites. Leccinum, a deep rooter, shows much lower La/Ce than the companion Russula and Lactarius samples from the same site. Similarly Suillus tissues demonstrated lower La/Ce when compared to Russula growing nearby. Lower La/Ce is consistent with enhanced dissolution of the mineral apatite, a common accessory phase. While the influence of symbiotic host (beech vs. oak vs. pine) may play some role in the distinctive REE signatures recorded by the fruiting bodies, we attribute the observed differences to organic acid production and tendency to colonize in different horizons of the soil profile. (1) Wallander, Plant and Soil, 2000; (2) Blum et</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EOSTr..93..134S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93..134S"><span>U.S. trade dispute with China over rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Showstack, Randy</p> <p>2012-03-01</p> <p>The U.S. government has brought a new trade case against China over rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">elements</span> that are used in a variety of electronic, optical, magnetic, and catalytic applications. REEs are plentiful in the <span class="hlt">Earth</span>'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 <span class="hlt">elements</span>, 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 <span class="hlt">earths</span>, as well as tungsten and molybdenum," the Office of the United States Trade Representative announced in a 13 March statement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JOM....66k2355K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JOM....66k2355K"><span>Addressing Rare-<span class="hlt">Earth</span> <span class="hlt">Element</span> Criticality: An Example from the Aviation Industry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ku, Anthony Y.; Dosch, Christopher; Grossman, Theodore R.; Herzog, Joseph L.; Maricocchi, Antonio F.; Polli, Drew; Lipkin, Don M.</p> <p>2014-11-01</p> <p>Rare-<span class="hlt">earth</span> (RE) <span class="hlt">elements</span> 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-<span class="hlt">earth</span> <span class="hlt">elements</span>, 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-<span class="hlt">earth</span> silicates offer a unique combination of environmental resistance, thermal expansion matching, thermal conductivity, and thermal stability across the service temperature window. Several pure rare-<span class="hlt">earth</span> silicates and solid solutions have been demonstrated in EBC applications. However, all rely on heavy rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (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-<span class="hlt">earth</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V52A..05D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V52A..05D"><span>Experimental Partitioning of Chalcophile <span class="hlt">Elements</span> between Mantle Silicate Minerals and Basaltic Melt at High Pressures and Temperatures - Implications for Sulfur <span class="hlt">Geochemistry</span> of Mantle and Crust</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dasgupta, R.; Jego, S.; Ding, S.; Li, Y.; Lee, C. T.</p> <p>2015-12-01</p> <p> crystallization. The model results are compared with the chalcophile <span class="hlt">element</span> abundance in oceanic basalts. We will discuss the implications of our new partitioning data and model results on sulfur and chalcophile <span class="hlt">element</span> <span class="hlt">geochemistry</span> of mantle source regions of ocean floor basalts and the fate of sulfides during mantle melting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AIPC.1362..201S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AIPC.1362..201S"><span>Development of Electronic Tongue for Detection of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Natural Surroundings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sarkar, Subrata; Purkait, Monirul; Roy, Jayanta Kumar; Datta, C.; Bhattacharyya, Nabarun; Sarkar, D.; Datta, Jagannath; Chowdhury, D. P.</p> <p>2011-09-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (like lanthanum) and other metals like zirconium, arsenic, potassium, copper etc. are some of the <span class="hlt">elements</span>, which are found in the natural surrounding. Since these metals have immense utility in the field of medical science, energy efficient electronic devices, nuclear energy domain, early and easy detection of such metals is very important. In the present work, voltammetric electronic tongue for detection and quantitative determination of these <span class="hlt">elements</span> has been explored. A sensor array comprising of noble metals (like gold, iridium, rhodium etc) has been developed and it exhibits remarkable sensitivity and promising results for detection and analysis of these <span class="hlt">elements</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993Metic..28Q.454W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Metic..28Q.454W"><span>Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Fractionation During Evaporation of Chondritic Material</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, J.; Davis, A. M.; Clayton, R. N.</p> <p>1993-07-01</p> <p>Evaporation experiments suggest that enrichments in the heavy isotopes of oxygen, magnesium, and silicon in some CAIs are caused by kinetic effects during evaporation [1]. Volatility-fractionated REE patterns found in some CAIs have been modeled with some success using equilibrium thermodynamics [2,3], but little is known about kinetic effects on REE patterns. We have begun an investigation of REE fractionation under conditions where large isotope effects are produced by the kinetic isotope effect. We synthesized a starting material containing CI chondritic relative proportions of MgO, Al2O3, SiO2, CaO, TiO2, and FeO, and doped it with 100 ppm each of the REE. Samples of this material were evaporated in a vacuum furnace [4] at 10^-6 torr and 1800 or 2000 degrees C for periods of a few seconds to 5 hr. The mass fraction evaporated ranged from 7.6 to 95.4%. Most residues consist of olivine and glass. Chemical compositions of the residues were determined by electron and ion microprobe. Results for selected <span class="hlt">elements</span> are shown in Fig. 1. There is no significant evaporation of Ca, Al, and Ti up to 95% mass loss; the evaporation behavior of Mg, Si, and Fe is similar to that found by Hashimoto [5]. There is no significant evaporation of most of the REE up to 95% mass loss. Ce is much more volatile than the other REE under these conditions: a tenfold negative Ce anomaly developed between 60 and 70% mass loss and the anomaly reached 5 X 10^-4 at 95% mass loss. A small Pr anomaly (50% Pr loss) also appeared in the highest-mass-loss residue. Thermodynamic calculations show that Ce has approximately the same volatility as other LREE under solar nebular oxygen fugacity, but is much more volatile than the other REE under oxidizing conditions [6]. We suspect that conditions in the residue in our vacuum evaporation experiments became oxidizing because evaporation reactions involving most major <span class="hlt">element</span> oxides involve release of oxygen. The four known HAL-type hibonite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MinPe.108..419F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MinPe.108..419F"><span>Platinum-group <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Zhuqing Fe-Ti-V oxide ore-bearing mafic intrusions in western Yangtze Block, SW China: control of platinum-group <span class="hlt">elements</span> by magnetite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fan, Hong-Peng; Zhu, Wei-Guang; Zhong, Hong; Bai, Zhong-Jie; He, De-Feng; Ye, Xian-Tao; Chen, Cai-Jie; Cao, Chong-Yong</p> <p>2014-06-01</p> <p>Platinum-group <span class="hlt">element</span> (PGE) <span class="hlt">geochemistry</span> combined with <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> and magnetite compositions are reported for the Mesoproterozoic Zhuqing Fe-Ti-V oxide ore-bearing mafic intrusions in the western Yangtze Block, SW China. All the Zhuqing gabbros display extremely low concentrations of chalcophile <span class="hlt">elements</span> and PGEs. The oxide-rich gabbros contain relatively higher contents of Cr, Ni, Ir, Ru, Rh, and lower contents of Pt and Pd than the oxide-poor gabbros. The abundances of whole-rock concentrations of Ni, Ir, Ru, and Rh correlate well with V contents in the Zhuqing gabbros, implying that the distributions of these <span class="hlt">elements</span> are controlled by magnetite. The fractionation between Ir-Ru-Rh and Pt-Pd in the Zhuqing gabbros is mainly attributed to fractional crystallization of chromite and magnetite, whereas Ru anomalies are mainly due to variable degrees of compatibility of PGE in magnetite. The order of relative incompatibility of PGEs is calculated to be Pd < Pt < Rh < Ir < Ru. The very low PGE contents and Cu/Zr ratios and high Cu/Pd ratios suggest initially S-saturated magma parents that were highly depleted in PGE, which mainly formed due to low degrees of partial melting leaving sulfides concentrating PGEs behind in the mantle. Moreover, the low MgO, Ni, Ir and Ru contents and high Cu/Ni and Pd/Ir ratios for the gabbros suggest a highly evolved parental magma. Fe-Ti oxides fractionally crystallized from the highly evolved magma and subsequently settled in the lower sections of the magma chamber, where they concentrated and formed Fe-Ti-V oxide ore layers at the base of the lower and upper cycles. Multiple episodes of magma replenishment in the magma chamber may have been involved in the formation of the Zhuqing intrusions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1236947','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1236947"><span>Rare <span class="hlt">earth</span> <span class="hlt">element</span> content of thermal fluids from Surprise Valley, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Andrew Fowler</p> <p>2015-09-23</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> measurements for thermal fluids from Surprise Valley, California. Samples were collected in acid washed HDPE bottles and acidified with concentrated trace <span class="hlt">element</span> clean (Fisher Scientific) nitric acid. Samples were pre-concentratated by a factor of approximately 10 using chelating resin with and IDA functional group and measured on magnetic sector ICP-MS. Samples include Seyferth Hot Springs, Surprise Valley Resort Mineral Well, Leonard's Hot Spring, and Lake City Mud Volcano Boiling Spring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750003762&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750003762&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drare%2Bearth"><span>Determination of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in Luna 16 regolith sample by chemical spectral method</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stroganova, N. S.; Ryabukhin, V. A.; Laktinova, N. V.; Ageyeva, L. V.; Galkina, I. P.; Gatinskaya, N. G.; Yermakov, A. N.; Karyakin, A. V.</p> <p>1974-01-01</p> <p>An analysis was made of regolith from layer A of the Luna 16 sample for rare <span class="hlt">earth</span> <span class="hlt">elements</span>, by a chemical spectral method. Chemical and ion exchange concentrations were used to determine the content of 12 <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8890S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8890S"><span>Geochemical constraints on <span class="hlt">Earth</span>'s core composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siebert, Julien</p> <p>2016-04-01</p> <p>The density of the core as measured from seismic-wave velocities is lower (by 10-15%) than that of pure iron, and therefore the core must also contain some light <span class="hlt">elements</span>. Geophysical and cosmochemical constraints indicate that obvious candidates for these light <span class="hlt">elements</span> include silicon, oxygen, and sulfur. These <span class="hlt">elements</span> have been studied extensively for the past 30 years but a joint solution fulfilling all the requirements imposed by cosmochemistry and <span class="hlt">geochemistry</span>, seismology, and models of <span class="hlt">Earth</span>'s accretion and core formation is still a highly controversial subject. Here are presented new experimental data in <span class="hlt">geochemistry</span> used to place constraints on <span class="hlt">Earth</span>'s core composition. Metal-silicate partitioning experiments were performed at pressures and temperatures directly similar to those that prevailed in a deep magma ocean in the early <span class="hlt">Earth</span>. The results show that core formation can reconcile the observed concentrations of siderophile <span class="hlt">elements</span> in the silicate mantle with geophysical constraints on light <span class="hlt">elements</span> in the core. Partitioning results also lead to a core containing less than 1 wt.% of sulfur, inconsistent with a S-rich layer to account for the observed structure of the outer core. Additionally, isotopic fractionations in core formation experiments are presented. This experimental tool merging the fields of experimental petrology and isotope <span class="hlt">geochemistry</span> represents a promising approach, providing new independent constraints on the nature of light <span class="hlt">elements</span> in the core.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.U11A..02T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.U11A..02T"><span>Imaging <span class="hlt">Earth</span>'s Interior based on Spectral-<span class="hlt">Element</span> and Adjoint Methods (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tromp, J.; Zhu, H.; Bozdag, E.</p> <p>2013-12-01</p> <p>We use spectral-<span class="hlt">element</span> and adjoint methods to iteratively improve 3D tomographic images of <span class="hlt">Earth</span>'s interior, ranging from global to continental to exploration scales. The spectral-<span class="hlt">element</span> method, a high-order finite-<span class="hlt">element</span> method with the advantage of a diagonal mass matrix, is used to accurately calculate three-component synthetic seismograms in a complex 3D <span class="hlt">Earth</span> model. An adjoint method is used to numerically compute Frechét derivatives of a misfit function based on the interaction between the wavefield for a reference <span class="hlt">Earth</span> model and a wavefield obtained by using time-reversed differences between data and synthetics at all receivers as simultaneous sources. In combination with gradient-based optimization methods, such as a preconditioned conjugate gradient or L-BSGF method, we are able to iteratively improve 3D images of <span class="hlt">Earth</span>'s interior and gradually minimize discrepancies between observed and simulated seismograms. Various misfit functions may be chosen to quantify these discrepancies, such as cross-correlation traveltime differences, frequency-dependent phase and amplitude anomalies as well as full-waveform differences. Various physical properties of the <span class="hlt">Earth</span> are constrained based on this method, such as elastic wavespeeds, radial anisotropy, shear attenuation and impedance contrasts. We apply this method to study seismic inverse problems at various scales, from global- and continental-scale seismic tomography to exploration-scale full-waveform inversion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20076087','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20076087"><span>Radioluminescence and thermoluminescence of rare <span class="hlt">earth</span> <span class="hlt">element</span> and phosphorus-doped zircon</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Karali, T.; Can, N.; Townsend, P.D.; Rowlands, A.P.; Hanchar, J.M.</p> <p>2000-06-01</p> <p>The radioluminescence and thermoluminescence spectra of synthetic zircon crystals doped with individual trivalent rare <span class="hlt">earth</span> <span class="hlt">element</span> (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-<span class="hlt">earth</span> 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-<span class="hlt">earth</span> lines of the same <span class="hlt">element</span>. 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 <span class="hlt">earth</span> ions. The temperature shifts of the peaks are considerable, up to 200{degree}, and much larger than those cited in other rare-<span class="hlt">earth</span>-doped crystals of LaF{sub 3} and Bi{sub 4}Ge{sub 3}O{sub 12}. The data clearly suggest that the rare-<span class="hlt">earth</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810057588&hterms=table+elements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtable%2Belements','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810057588&hterms=table+elements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtable%2Belements"><span>Composition of the <span class="hlt">earth</span>'s upper mantle. I - Siderophile trace <span class="hlt">elements</span> in ultramafic nodules</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morgan, J. W.; Wandless, G. A.; Petrie, R. K.; Irving, A. J.</p> <p>1981-01-01</p> <p>The considered investigation is concerned with a reexamination of the question of the distribution of siderophile <span class="hlt">elements</span> in the <span class="hlt">earth</span>'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 <span class="hlt">elements</span>. 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 <span class="hlt">elements</span> (Au, Ge, Ir, Ni, Os, Pd, and Re) and 9 volatile <span class="hlt">elements</span> (Ag, Bi, Cd, In, Sb, Se, Te, Tl, and Zn). The siderophile <span class="hlt">element</span> data reveal interesting inter-<span class="hlt">element</span> correlations, which were not apparent from the compiled abundance tables of Ringwood and Kesson (1976) and Chou (1978).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1234401','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1234401"><span>Fluid rare <span class="hlt">earth</span> <span class="hlt">element</span> anlayses from wells RN-12 and RN-19, Reykjanes, Iceland</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Andrew Fowler</p> <p>2015-07-24</p> <p>Results for fluid rare <span class="hlt">earth</span> elment analyses from Reykjanes wells RN-12 and RN-19. The data have not been corrected for flashing. Samples preconcetrated using chelating resin with IDA functional group (InertSep ME-1). Analyzed using and <span class="hlt">Element</span> magnetic sctor ICP-MS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=274163','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=274163"><span>Interactions between exogenous rare <span class="hlt">earth</span> <span class="hlt">elements</span> and phosphorus leaching in packed soil columns</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1234403','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1234403"><span>Compilation of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Analyses from US Geothermal Fields and Mid Ocean Ridge Hydrothermal Vents</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Andrew Fowler</p> <p>2015-10-01</p> <p>Compilation of rare <span class="hlt">earth</span> <span class="hlt">element</span> and associated major and minor dissolved constituent analytical data for USA geothermal fields and global seafloor hydrothermal vents. Data is in original units. Reference to and use of this data should be attributed to the original authors and publications according to the provisions outlined therein.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1261977','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1261977"><span>Method to Recover Media Ligand Losses During Sorption of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from Simulated Geothermal Brines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dean Stull</p> <p>2016-05-24</p> <p>This document describes the method and results of an in-situ experiment used to confirm that ligand bleed from a sorptive media can be contained. The experiment focused on maintaining the media's sorption of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) obtained from a simulated geothermal brine doped with known mineral concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=279057&keyword=Recycling&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78716517&CFTOKEN=80201246','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=279057&keyword=Recycling&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78716517&CFTOKEN=80201246"><span>Technical Information Resource on Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Now Available to Public and Private Sector Stakeholders</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>A new EPA technical information resource, “Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span>: 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...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=250918','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=250918"><span>Preliminary study on using rare <span class="hlt">earth</span> <span class="hlt">elements</span> to trace non-point source phosphorous loss</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The environmental fate of phosphorus (P) is of concern as P is a primary cause of freshwater eutrophication. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=234552','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=234552"><span>Tracing sediment movement on semi-arid watershed using Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> 1988</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>A multi-tracer method employing rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995PhDT.........7M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995PhDT.........7M"><span>Experimental <span class="hlt">Geochemistry</span> of Iodine, Argon and Xenon: Implications for the Outgassing Histories of the <span class="hlt">Earth</span> and Mars.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Musselwhite, Donald Stanley</p> <p>1995-01-01</p> <p>This dissertation presents results from experiments measuring the silicate-melt solubility of iodine conducted at one atmosphere and the mineral/melt partitioning behavior of iodine, argon and xenon conducted at one atmosphere and 15kbars. The solubility of iodine in silicate melts is strongly correlated with the molar volume and the degree of polymerization of the melt. Results of mineral/melt partitioning studies show that iodine is at least ten times more incompatible than xenon. The values of argon mineral/melt partition coefficients determined in this study fall in the low range of those determined in previous investigations. These results, along with other parameters are used to assess the timing and extent of early mantle outgassing for the <span class="hlt">Earth</span> and Mars. If outgassing alone is responsible for the xenon isotopic composition of the mantle source of the mid-ocean ridge basalts, then the mantle outgassed 99 percent of it's volatiles within the first 100 million years following the nucleosynthesis process, which preceded the formation of the solar system. Furthermore, the mantle experienced a nearly 100 percent molten state sometime during this period. Straight forward early outgassing cannot explain the isotopic composition of the martian atmosphere. A two-stage outgassing scenario can explain it, but requires the existence of an as yet unsampled mantle reservoir. Alternatively, water solubility fractionation very early in martian history may have played a significant role in determining the isotopic composition of the present-day martian atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EurSS..45..983P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EurSS..45..983P"><span>Concentrations of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in soils of the Prioksko-Terrasnyi state biospheric reserve</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perelomov, L. V.; Asainova, Zh. S.; Yoshida, S.; Ivanov, I. V.</p> <p>2012-10-01</p> <p>The concentrations of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> were studied in the profiles of soddy podburs and mucky-humus gley soils. The soil horizons differed significantly in the contents of Corg (0-26%), the physical clay (<0.01 mm) fraction (3-31%), the acidity (pH 4 to 5.5), and the presence/absence of Al-Fe-humus accumulations. The most significant relationship was observed between the concentrations of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> and the physical clay content, particularly for Nd: x(Nd, mg/kg) = 7 + 1.6 y (fraction <0.01 mm, %). Weak biogenic accumulations in the upper horizons were observed for Nd, Ce, and Dy; Nd, Pr, and La accumulated in the Al-Fe-humus illuvial horizon. The concentrations of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in the studied soils formed the following sequence (mg/kg): Nd (20-101)-Ce (10-44)-La, Sm, Gd, Dy, Yb (3-20)-Pr (1-4)-Ho (0.1-0.4)-Tm, Lu, and Tl (0.0). A clear trend was observed to higher contents of even-numbered <span class="hlt">elements</span> as compared with odd-numbered <span class="hlt">elements</span>, excluding La.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26739864','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26739864"><span>Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span> in Magnets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun</p> <p>2016-02-01</p> <p>Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for <span class="hlt">elemental</span> analysis of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in NdFeB magnets. Luminescence spectra of chloride compounds of <span class="hlt">elements</span> in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in NdFeB magnets, particularly dysprosium and terbium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8880D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8880D"><span>Geochemical behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> of the hydrothermal alterations within the Tepeoba porphyry Cu-Mo-Au deposits at Balikesir, NW Turkey</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doner, Zeynep; Abdelnasser, Amr; Kiran Yildirim, Demet; Kumral, Mustafa</p> <p>2016-04-01</p> <p> <span class="hlt">earth</span> <span class="hlt">elements</span> <span class="hlt">geochemistry</span>; Tepeoba porphyry Cu-Mo-Au deposits; Balikesir; Turkey</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030422','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030422"><span>Mineralogical anomalies and their influences on <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> of the main workable coal beds from the Dafang Coalfield, Guizhou, China</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dai, S.; Ren, D.; Li, D.; Chou, C.-L.; Luo, K.</p> <p>2006-01-01</p> <p>Mineralogy and <span class="hlt">geochemistry</span> of the No. 11 Coal bed were investigated by using inductively-coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF), scanning electron microscopy equipped with energy-dispersive X-ray (SEM-EDX), sequential chemical extraction procedure (SCEP), and optical microscopy. The results show that the No. 11 Coal bed has very high contents of veined quartz (Vol. 11.4%) and veined ankerite (Vol. 10.2 %). The veined ankerite was generally coated by goethite and the veined quartz embraced chalcopyrite, sphalerite, and selenio-galena. In addition, a trace amount of kaolinite was filled in the veins. These seven minerals often occur in the same veins. The formation temperatures of the veined ankerite and quartz are 85??C and 180??C respectively, indicating their origins of iron-rich calcic and siliceous low-temperature hydrothermal fluids in different epigenetic periods. Studies have also found that the veined quartz probably formed earlier than the veined ankerite, and at least three distinct ankerite formation stages were observed by the ration of Ca/Sr and Fe/Mn of ankerite. The mineral formation from the early to late stage is in order of sulfide, quartz, kaolinite, ankerite, and goethite. The veined ankerite is the dominant source of Mn, Cu, Ni, Pb, and Zn, which are as high as 0.09%, 74.0 ??g/g, 33.6 ??g/g, 185 ??g/g, and 289 ??g/g in this coal seam, respectively. However, the veined quartz is the main carrier of Pd, Pt, and Ir, which are 1.57 ??g/g, 0.15 ??g/g, and 0.007 ??g/g in this coal seam, respectively. In addition, chalcopyrite, sphalerite, and selenio-galena of hydrothermal origin were determined in the veined quartz, and these three sulfide minerals are also important carriers of Cu, Zn and Pb in the No. 11 Coal bed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E2641P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E2641P"><span>Study on Orbital Decay of Near <span class="hlt">Earth</span> Satellites with KS Orthogonal <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ps, Sandeep</p> <p></p> <p>STUDY ON ORBITAL DECAY OF NEAR <span class="hlt">EARTH</span> SATELLITES WITH KS ORTHOGONAL <span class="hlt">ELEMENTS</span> SANDEEP P S The knowledge of satellite orbit decay and its expected life prior to launch is necessary for mission planning purpose. Several sets of data for various parametric studies is sought quite often, it is necessary to minimize computational time involved for generating decay predictions, keeping the prediction accuracy normally good. A number of factors play dominant role in perturbation modelling for near <span class="hlt">earth</span> satellites such as oblateness of the <span class="hlt">Earth</span>, presence of the atmosphere, luni-solar attraction and solar radiation pressure. This paper concerns with the study of orbital decay of near <span class="hlt">earth</span> satellites with KS orthogonal <span class="hlt">elements</span>, which provide accurate orbit predictions at low computational time. Perturbations considered are due to oblateness of the <span class="hlt">Earth</span> and the atmospheric drag. The Earth’s zonal harmonic terms J2 to J6 are included and the drag is modeled with an analytical diurnally oblate atmosphere. Effect of Earth’s geomagnetic and solar activity is included in density and density scale height computations. JACCHIA77 atmospheric model is utilized. The developed software is validated with the orbital data of decayed objects taken from www.space-track.org.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.V22A1005N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.V22A1005N"><span>Siderophile <span class="hlt">Element</span> Compositions of Lunar Impact Breccias: Implications for the Cataclysm and Early <span class="hlt">Earth</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Norman, M.; Bennett, V.; Ryder, G.</p> <p>2001-12-01</p> <p>Highly siderophile <span class="hlt">element</span> signatures of the two main textural and compositional groups of Apollo 17 impact melt breccias (poikilitics and aphanites) are consistent with EH chondrite impactor(s). Similar siderophile <span class="hlt">element</span> signatures in both types of breccias implies either that multiple EH chondritic impactors were delivered to the Serenitatis region of the Moon within a narrow time interval, or that the two groups of breccias are petrogenetically related to a single impact event. To the extent that these breccias can be linked with the Serenitatis basin-forming event, this identifies one type of planetesimal responsible for creating a large nearside lunar basin, possibly during a terminal cataclysm. Owing to its larger size and greater gravitational focusing, the <span class="hlt">Earth</span> would have experienced a significantly greater cratering rate (20x) and mass accretion rate (100x) compared to the Moon. If there was a terminal cataclysm, the <span class="hlt">Earth</span> must have been hit by several large impacts during the crucial period in which the oldest preserved continental crust was forming and early life was evolving. If EH chondrites are found to be an important population for creating the 3.8 to 4.0 Ga lunar basins, their fractionated HSE pattern may have contributed to mantle heterogeneity on <span class="hlt">Earth</span>. However, the dry and highly reduced nature of EH chondrites would preclude a significant contribution from these planetesimals to the volatile budget of the <span class="hlt">Earth</span> and the oxidation of the terrestrial mantle. Additional studies of highly siderophile <span class="hlt">elements</span> in lunar impact breccias and ancient terrestrial rocks are needed to establish the composition of infalling planetesimals on the early <span class="hlt">Earth</span> and Moon, and the contribution of large impact events to the subsequent evolution of the <span class="hlt">Earth</span> and other terrestrial planets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21222359','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21222359"><span>Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Jurassic coals in the Feke and Kozan (Adana) Areas, Eastern Taurides, Turkey</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kara-Gulbay, R.; Korkmaz, S.</p> <p>2009-07-01</p> <p>In this study, trace <span class="hlt">element</span> and organic matter-trace <span class="hlt">element</span> relation between Jurassic coals exposed in three different fields in the eastern Taurides were examined and their enrichment values with respect to upper crust values were calculated and the coal characteristics were also compared with world arithmetic means and those from the U.S. In comparison to the Feke and Kizilin coals, Pb, Zn, Ag, and Hg <span class="hlt">element</span> contents of the Gedikli coals are considerably high; Ni, As, and Ge contents are moderately high; and Cr, Cu, Co, Cd, Sb, Ga, and Sn contents are slightly high. The <span class="hlt">element</span> concentrations are very similar to those of other fields. In the Gedikli coals, Sr content is extremely low and Ba content is slightly low with respect to other fields. Re, Mo, U, V, and B <span class="hlt">element</span> concentrations are different for each of three fields. The major <span class="hlt">element</span> contents of the Feke, Gedikli, and Kizilin coals were correlated with world arithmetic means and average values of coals from the U.S. and Fe, K, Mg, and Na concentrations were found to be similar. Ti and Al contents of the world and USA coals are higher while Ca and Mn concentrations are lower. Considering trace <span class="hlt">element</span> contents of the world and U.S. coals, Ba is considerably high, Cu and Zr are moderately high, and Ga, Rb, and Sc <span class="hlt">elements</span> are slightly high. In comparison to world arithmetic means and U.S. coals, Sr content of the Feke and Kizilin coals are very high while those of the Gedikli coals are lower. For major and trace <span class="hlt">elements</span>, factors of enrichment with respect to upper crust values were also calculated. The highest enrichment values were calculated for Ca and S. Except for Se and Rb, all other trace <span class="hlt">elements</span> are enriched with respect to upper crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014IJEaS.103.1945W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014IJEaS.103.1945W"><span>Volatile (sulphur and chlorine), major, and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of mafic to intermediate tephras from the Chilean Southern Volcanic Zone (33-43°S)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wehrmann, Heidi; Hoernle, Kaj; Jacques, Guillaume; Garbe-Schönberg, Dieter; Schumann, Kai; Mahlke, Julia; Lara, Luis E.</p> <p>2014-10-01</p> <p>Here we present the first systematic investigation of volatile <span class="hlt">geochemistry</span> along the Southern Volcanic Zone (SVZ) of Chile. Holocene olivine-hosted melt inclusions in the most mafic tephras sampled from 16 volcanoes along the volcanic front of the SVZ between 33°S and 43°S were analysed for pre-eruptive sulphur, chlorine, and major <span class="hlt">element</span> contents. These results are combined with trace <span class="hlt">element</span> compositions of the host whole rocks. The highest fractionation-corrected gas contents occur in the least-degassed melt inclusions from small monogenetic cones of Los Hornitos, Cabeza de Vaca, and Apagado from both the transitional and the southern-central SVZ, reaching ~3,000 μg/g S and 1,400 μg/g Cl, while the lowest abundances of ~1,100 μg/g S and ~600 μg/g Cl were found in the central SVZ at Volcán Lonquimay, Volcán Llaima, and Volcán Villarrica. Chlorine co-varies with trace <span class="hlt">element</span> indicators for the degree of melting and/or source enrichment, such that the lowest Cl contents are found in high-degree melts from the most depleted mantle sources. The size of the volcanic edifices correlates inversely with Cl abundances in the melt. This could reflect more extensive degassing during ascent through the complex magma plumbing systems beneath the stratovolcanoes or greater dilution during larger degrees of melting of more depleted sources, or a combination of these factors. Compared to other subduction zones, the SVZ melt inclusions exhibit Cl and S abundances in the same range as most of those from the Central American and those from the Marianas arcs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10376325','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10376325"><span>Heavy metals and rare <span class="hlt">earth</span> <span class="hlt">elements</span> source-sink in some Egyptian cigarettes as determined by neutron activation analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nada, A; Abdel-Wahab, M; Sroor, A; Abdel-Haleem, A S; Abdel-Sabour, M F</p> <p>1999-07-01</p> <p>Heavy metals and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in two types of cigarettes were studied. The contents of trace <span class="hlt">elements</span> were determined by using delayed neutron activation analysis. In the present study 11 <span class="hlt">elements</span> have been detected in popular and fine brand cigarettes marketed in Egypt. Evaluation of these <span class="hlt">elements</span> with their potential hazards for smokers is briefly discussed. The material balance (source and sink) for each <span class="hlt">element</span> was determined. Also the ratio of <span class="hlt">element</span> recovery to the total amount was assessed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23811462','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23811462"><span>Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of Manilkara zapota (L.) P. Royen, fruit from winder, Balochistan, Pakistan in perspective of medical geology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hamza, Salma; Naseem, Shahid; Bashir, Erum; Rizwani, Ghazala H; Hina, Bushra</p> <p>2013-07-01</p> <p>An integrated study of rocks, soils and fruits of Manilkara zapota (L.) (Sapotaceae) of Winder area have been carried out to elaborate trace <span class="hlt">elements</span> relationship between them. The igneous rocks of the study area have elevated amount of certain trace <span class="hlt">elements</span>, upon weathering these <span class="hlt">elements</span> are concentrated in the soil of the area. The trace <span class="hlt">elements</span> concentration in the soil were found in the range of 0.8-197 for Fe, 1.23-140 for Mn, 0.03-16.7 for Zn, 0.07-9.8 for Cr, 0.05-2.0 for Co, 0.52-13.3 for Ni, 0.03-8.8 for Cu, 0.08-10.55 for Pb and 0.13-1.8μg/g for Cd. The distribution pattern of <span class="hlt">elements</span> in the rocks and soils reflected genetic affiliation. Promising <span class="hlt">elements</span> of edible part of the fruit were Fe (14.17), Mn (1.49), Cr (2.96), Ni (1.13), Co (0.92), Cu (1.70) and Zn (1.02μg/g). The concentration of these <span class="hlt">elements</span> in the fruits is above the optimum level of recommended dietary intake, probably due to this, disorder in the human health is suspected in the inhabitants of the area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMDI21A4272D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMDI21A4272D"><span>The Fate of Sulfur during Decompression Melting of Peridotite and Crystallization of Basalts - Implications for Sulfur <span class="hlt">Geochemistry</span> of MORB and the <span class="hlt">Earth</span>'s Upper Mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, S.; Dasgupta, R.</p> <p>2014-12-01</p> <p>Magmatism in mid-ocean ridges is the main pathway of sulfur (S) from the <span class="hlt">Earth</span>'s mantle to the surficial reservoir. MORB is generally considered sulfide saturated due to the positive correlation between S and FeOT concentration (e.g., [1]). However, most MORBs are differentiated, and both S content and sulfur concentration at sulfide saturation (SCSS) change with P, T, and magma composition (e.g., [2]). Therefore, it remains uncertain, from the MORB chemistry alone, whether mantle melts parental to MORB are sulfide saturated. In this study, we modeled the behavior of S during isentropic partial melting of a fertile peridotite using pMELTS [3] and an SCSS parameterization [4]. Our results show that during decompression melting, at a fixed mantle potential temperature, TP (e.g., 1300 °C), SCSS of aggregate melt first slightly increases then decreases at shallower depth with total variation <200 ppm. However, an increase of TP results in a significant increase of SCSS of primitive melts. Our model shows that at 15% melting (F), sulfide in the residue is exhausted for a mantle with <200 ppm S. The resulted sulfide-undersaturated partial melts contain <1000 ppm S and are 4-6 times enriched in Cu compared to the source. In order to compare our modeled results directly to the differentiated basalts, isobaric crystallization calculation was performed on 5, 10, and 15% aggregate melts. SCSS changes along liquid line of descent with a decrease in T and increase in FeOT. Comparison of S contents between the model results and MORB glasses [5] reveals that many MORBs derive from sulfide undersaturated melts. Further, for a TP of 1300-1350 °C and F of 10-15 wt.%, reproduction of self-consistent S, and Cu budget of many MORB glasses requires that S of their mantle source be ~25-200 ppm. We will discuss the interplay of TP, average F, and the conditions of differentiation to bracket the S <span class="hlt">geochemistry</span> of MORB and MORB source mantle and develop similar systematics for OIBs and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAfES.100..675A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAfES.100..675A"><span>Trace <span class="hlt">elements</span> <span class="hlt">geochemistry</span> of kerogen in Upper Cretaceous sediments, Chad (Bornu) Basin, northeastern Nigeria: Origin and paleo-redox conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adegoke, Adebanji Kayode; Abdullah, Wan Hasiah; Hakimi, Mohammed Hail; Sarki Yandoka, Babangida M.; Mustapha, Khairul Azlan; Aturamu, Adeyinka Oluyemi</p> <p>2014-12-01</p> <p>Trace <span class="hlt">element</span> contents in isolated kerogen from Upper Cretaceous sediments within Gongila and Fika formations in the Chad (Bornu) Basin, northeastern Nigeria were determined using Inductively-coupled plasma mass spectrometer (ICP-MS), in order to infer the origin of the organic matter and the paleo-redox conditions during their sedimentation. The concentrations of the <span class="hlt">elements</span> in the kerogen samples varied from 1.01 to 24,740 ppm. The distribution of <span class="hlt">elements</span> shows that Fe is the most abundant <span class="hlt">element</span> in Chad (Bornu) Basin kerogen, followed by Ce. Among the biophile <span class="hlt">elements</span>, V is the most abundant, followed by Ni and Co in that order. Statistical evaluation of the <span class="hlt">elemental</span> composition data shows that As, Ce, Pb, V, Cr, Fe, Co, Ni and U exhibit good positive correlations with each other. Molybdenum, on the other hand displays no obvious correlation with most of the trace <span class="hlt">elements</span> determined including TOC, but has good positive correlation with TS and negative correlation with Tmax, Ce and Th, which suggests that the concentration of Mo decreases with increasing maturity and vice versa. Some trace <span class="hlt">element</span> concentrations and their ratios suggest mixed marine and terrigenous source input for the organic matter (kerogen) in Chad (Bornu) Basin. More so, the concentrations of redox-sensitive <span class="hlt">elements</span>, such as V, Ni, Cu, Cr Mo and Mn, in the kerogen samples suggest dysoxic bottom water conditions within the Gongila and Fika sediments. Cross-plots of V and Ni and V/(V + Ni) ratio also indicate that the organic matter of these samples was deposited in slightly reducing environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT.......140S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT.......140S"><span>Structural Responses and Finite <span class="hlt">Element</span> Modeling of Hakka Tulou Rammed <span class="hlt">Earth</span> Structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sranislawski, Daniel</p> <p></p> <p>Hakka Tulous are rammed <span class="hlt">earth</span> structures that have survived the effects of aging and natural <span class="hlt">elements</span> upwards of even over a thousand years. These structures have housed the Hakka people of the Fujian Province, China in natural yet modern housing that has provided benefits over newer building materials. The key building material, rammed <span class="hlt">earth</span>, which is used for the walls of the Hakka Tulou structures, has provided structural stability along with thermal comfort to the respective inhabitants of the Hakka Tulous. Through material testing and analysis this study has examined how the Tulou structures have maintained their structural stability while also providing thermal comfort. Reports of self healing cracks in the rammed <span class="hlt">earth</span> walls were also analyzed for their validity in this study. The study has found that although the story of the self healing crack cannot be validated, there is reason to believe that with the existence of lime, some type of autogenous healing could occur on a small scale. The study has also found, through the use of nondestructive testing, that both the internal wooden systems (flooring, roof, and column support) and the rammed <span class="hlt">earth</span> walls, are still structurally sound. Also, rammed <span class="hlt">earth</span>'s high thermal mass along with the use of sufficient shading has allowed for a delay release of heat energy from the walls of the Tulous, thus providing thermal comfort that can be felt during both night and day temperatures. The Hakka Tulou structures have been found to resist destruction from natural disasters such as strong earthquakes even when more modern construction has not. Through finite <span class="hlt">element</span> modeling, this study has shown that the high volume of rammed <span class="hlt">earth</span> used in the construction of the Hakka Tulous helps dissipate lateral force energy into much lower stresses for the rammed <span class="hlt">earth</span> wall. This absorption of lateral force energy allows the rammed <span class="hlt">earth</span> structures to survive even the strongest of earthquakes experienced in the region. The Hakka</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAESc.117...33L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAESc.117...33L"><span>Geochemical behaviors of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in groundwater along a flow path in the North China Plain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Haiyan; Guo, Huaming; Xing, Lina; Zhan, Yanhong; Li, Fulan; Shao, Jingli; Niu, Hong; Liang, Xing; Li, Changqing</p> <p>2016-03-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) <span class="hlt">geochemistry</span> is a useful tool in delineating hydrogeochemical processes and tracing solute transport, which can be used to reveal groundwater chemical evolution in the complexed groundwater systems of the North China Plain (NCP). Groundwaters and sediments were collected approximately along a flow path in shallow and deep aquifers of the NCP to investigate REE <span class="hlt">geochemistry</span> as a function of distance from the recharge zone. Groundwater REE concentrations are relatively low, with ranges from 81.2 to 163.6 ng/L in shallow groundwaters, and from 65.2 to 133.7 ng/L in deep groundwaters. Speciation calculation suggests that dissolved REEs mainly occur as dicarbonato (Ln(CO3)2-) and carbonato (LnCO3+) complexes. Although along the flow path groundwater REE concentrations do not vary substantially, relatively lower HREEs are observed in central plain (Zone II) compared to recharge area (Zone I) and discharge plain (Zone III). Shale-normalized REE patterns are characterized by different degrees of enrichment in the HREEs, as indicated by the variation in average (Er/Nd)NASC value. The similar REE compositions and shale-normalized REE patterns of shallow and deep groundwaters demonstrate that interactions of groundwaters between shallow and deep aquifers possibly occur, which is likely due to the long-term groundwater over-exploration. Cerium anomalies (Ce/Ce∗ = CeNASC/(LaNASC × PrNASC)0.5) generally increase from Zone I, through Zone II, to Zone III, with trends from 0.79 to 3.58, and from 1.22 to 2.43 in shallow groundwaters and deep groundwaters, respectively. This is consistent with the variations in oxidation-reduction potential and redox sensitive components (i.e., dissolved Fe, Mn, NO3- and As concentrations) along the flow path. Positive Ce anomaly and redox indicators suggest that redox conditions progressively evolve from oxic to moderate anaerobic in the direction of groundwater flow. In the recharge zone (Zone I), groundwater low</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Litho.177..297L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Litho.177..297L"><span>Petrology, major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span>, geochronology, and isotopic composition of granitic intrusions from the vicinity of the Bosumtwi impact crater, Ghana</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Losiak, Anna; Schulz, Toni; Buchwaldt, Robert; Koeberl, Christian</p> <p>2013-09-01</p> <p>The Bosumtwi crater is 10.5 km in diameter, 1.07 Ma old, well preserved impact structure located in Ghana (centered at 06°30‧N, 01°25‧W). It was excavated in rocks of the Early Proterozoic Birimian Supergroup, part of the West African craton. Here, we present a full and detailed characterization of the three granitoid complexes and one mafic dike in the vicinity of the Bosumtwi crater in terms of petrology, major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span>, geochronology, and isotopic composition. This allows us to characterize magmatic evolution of the West African Craton in this area and better understand the geological framework and target rocks of the impact. This study shows that the similar composition (strongly peraluminous muscovite granites and granodiorites) and age (between 2092 ± 6 Ma and 2098 ± 6 Ma) of all granitic intrusions in the proximity of the Bosumtwi crater suggest that they are co-genetic. Granitoids were probably formed as a result of anatexis of TTGs (or rocks derived from them) at relatively low pressure and temperature. We propose that the intrusions from the Bosumtwi area are genetically related to the Banso granite occurring to the east of the crater and can be classified as basin-type, late-stage granitoids. Also a mafic dike located to the NE of the Bosumtwi crater seems to be genetically related to those felsic intrusions. Based on those findings a revised version of the geological map of the Bosumtwi crater area is proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JSAES..37..136R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JSAES..37..136R"><span>Provenance of late Oligocene to quaternary sediments of the Ecuadorian Amazonian foreland basin as inferred from major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and Nd-Sr isotopic composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roddaz, Martin; Christophoul, Frédéric; Burgos Zambrano, José David; Soula, Jean-Claude; Baby, Patrice</p> <p>2012-08-01</p> <p>Oligocene to Quaternary deposits from the Oriente Amazonian foreland basin (Ecuador and Peru) were analyzed for major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> (46 and 32 samples respectively) and Nd-Sr isotopic systematics (n = 10). Chemical Index of Alteration values lower than those of other Amazonian foreland basin sediments and scattering along the AK join in the A-CN-K diagram indicate that the Oriente foreland basin has been continuously fed by poorly to moderately weathered sediments having an overall Andesitic composition since the Oligocene. Chemical ratios such as Cr/Th and Th/Sc as well as Eu anomaly and Nd-Sr isotopic compositions indicate that most of the analyzed sediments contained a greater proportion of volcanic arc rock material than the other Amazonian foreland basin sediments. When compared with the older sediments The Quaternary sediments are characterized by a greater contribution of the volcanic arc source. The composition of the sediments deposited in the Ecuadorian Amazonian foreland basin is mainly controlled by geodynamic processes. We suspect the Late Pliocene-Pleistocene subduction of the Carnegie ridge to be responsible for the back arc volcanism feeding the Amazonian foreland with more basic materials. Input of young Ecuadorian volcanic rocks may explain the difference in Sr and Nd isotopic ratios of suspended sediments between the Solimoes and the Madeira rivers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1979/0926/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1979/0926/report.pdf"><span>Major-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Silent Canyon-Black Mountain peralkaline volcanic centers, northwestern Nevada Test Site: applications to an assessment of renewed volcanism</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Crowe, Bruce M.; Sargent, Kenneth A.</p> <p>1979-01-01</p> <p>The Silent Canyon and Black Mountain volcanic centers are located in the northern part of the Nevada Test Site. The Silent Canyon volcanic center is a buried cauldron complex of Miocene age (13-15 m.y.). Black Mountain volcanic center is an elliptical-shaped cauldron complex of late Miocene age. The lavas and tuffs of the two centers comprise a subalkaline-peralkaline association. Rock types range from quartz normative subalkaline trachyte and rhyolite to peralkaline comendite. The Gold Flat Member of the Thirsty Canyon Tuff (Black Mountain) is a pantellerite. The major-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Black Mountain-Silent Canyon volcanic centers differs in the total range and distribution of Si02, contents, the degree of peralkalinity (molecular Na2O+K2O>Al2O3) and in the values of total iron and alumina through the range of rock types. These differences indicate that the suites were unrelated and evolved from differing magma bodies. The Black Mountain volcanic cycle represents a renewed phase of volcanism following cessation of the Timber Mountain-Silent Canyon volcanic cycles. Consequently, there is a small but numerically incalculable probability of recurrence of Black Mountain-type volcanism within the Nevada Test Site region. This represents a potential risk with respect to deep geologic storage of high-level radioactive waste at the Nevada Test Site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11378929','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11378929"><span>Radon (222Rn) level variations on a regional scale: influence of the basement trace <span class="hlt">element</span> (U, Th) <span class="hlt">geochemistry</span> on radon exhalation rates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ielsch, G; Thiéblemont, D; Labed, V; Richon, P; Tymen, G; Ferry, C; Robé, M C; Baubron, J C; Béchennec, F</p> <p>2001-01-01</p> <p>The approach proposed in this study provides insight into the influence of the basement <span class="hlt">geochemistry</span> on the spatial distribution of radon (222Rn) levels both at the soil/atmosphere interface and in the atmosphere. We combine different types of in situ radon measurements and a geochemical classification of the lithologies, based on 1/50,000 geological maps, and on their trace <span class="hlt">element</span> (U, Th) contents. The advantages of this approach are validated by a survey of a stable basement area of Hercynian age, located in South Brittany (western France) and characterized by metamorphic rocks and granitoids displaying a wide range of uranium contents. The radon source-term of the lithologies, their uranium content, is most likely to be the primary parameter which controls the radon concentrations in the outdoor environment. Indeed, the highest radon levels (> or = 100 Bq m-3 in the atmosphere, > or = 100 mBq m-2 s-1 at the surface of the soil) are mostly observed on lithologies whose mean uranium content can exceed 8 ppm and which correspond to peraluminous leucogranites or metagranitoids derived from uraniferous granitoids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27842718','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27842718"><span>Concentrations and health risk assessment of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in vegetables from mining area in Shandong, China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhuang, Maoqiang; Zhao, Jinshan; Li, Suyun; Liu, Danru; Wang, Kebo; Xiao, Peirui; Yu, Lianlong; Jiang, Ying; Song, Jian; Zhou, Jingyang; Wang, Liansen; Chu, Zunhua</p> <p>2017-02-01</p> <p>To investigate the concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in vegetables and assess human health risk through vegetable consumption, a total of 301 vegetable samples were collected from mining area and control area in Shandong, China. The contents of 14 rare <span class="hlt">earth</span> <span class="hlt">elements</span> were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The total rare <span class="hlt">earth</span> <span class="hlt">elements</span> in vegetables from mining and control areas were 94.08 μg kg(-1) and 38.67 μg kg(-1), respectively, and the difference was statistically significant (p < 0.05). The leaf vegetable had the highest rare <span class="hlt">earth</span> <span class="hlt">elements</span> concentration (984.24 μg kg(-1) and 81.24 μg kg(-1) for mining and control areas, respectively) and gourd vegetable had the lowest rare <span class="hlt">earth</span> <span class="hlt">elements</span> concentration (37.34 μg kg(-1) and 24.63 μg kg(-1) for mining and control areas, respectively). For both areas, the rare <span class="hlt">earth</span> <span class="hlt">elements</span> concentration in vegetables declined in the order of leaf vegetable > taproot vegetable > alliaceous vegetable > gourd vegetable. The rare <span class="hlt">earth</span> <span class="hlt">elements</span> distribution patterns for both areas were characterized by enrichment of light rare <span class="hlt">earth</span> <span class="hlt">elements</span>. The health risk assessment demonstrated that the estimated daily intakes (0.69 μg kg(-1) d(-1) and 0.28 μg kg(-1) d(-1) for mining and control areas, respectively) of rare <span class="hlt">earth</span> <span class="hlt">elements</span> through vegetable consumption were significantly lower than the acceptable daily intake (70 μg kg(-1) d(-1)). The damage to adults can be neglected, but more attention should be paid to the effects of continuous exposure to low levels of rare <span class="hlt">earth</span> <span class="hlt">elements</span> on children.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.128...29H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.128...29H"><span>Preservation of NOM-metal complexes in a modern hyperalkaline stalagmite: Implications for speleothem trace <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hartland, Adam; Fairchild, Ian J.; Müller, Wolfgang; Dominguez-Villar, David</p> <p>2014-03-01</p> <p>We report the first quantitative study of the capture of colloidal natural organic matter (NOM) and NOM-complexed trace metals (V, Co, Cu, Ni) in speleothems. This study combines published NOM-metal dripwater speciation measurements with high-resolution laser ablation ICPMS (LA-ICPMS) and sub-annual stable isotope ratio (δ18O and δ13C), fluorescence and total organic carbon (TOC) analyses of a fast-growing hyperalkaline stalagmite (pH ˜11) from Poole’s Cavern, Derbyshire UK, which formed between 1997 and 2008 AD. We suggest that the findings reported here elucidate trace <span class="hlt">element</span> variations arising from colloidal transport and calcite precipitation rate changes observed in multiple, natural speleothems deposited at ca. pH 7-8. We find that NOM-metal(aq) complexes on the boundary between colloidal and dissolved (˜1 nm diameter) show an annual cyclicity which is inversely correlated with the alkaline <span class="hlt">earth</span> metals and is explained by calcite precipitation rate changes (as recorded by kinetically-fractionated stable isotopes). This relates to the strength of the NOM-metal complexation reaction, resulting in very strongly bound metals (Co in this system) essentially recording NOM co-precipitation (ternary complexation). More specifically, empirical partition coefficient (Kd) values between surface-reactive metals (V, Co, Cu, Ni) [expressed as ratio of trace <span class="hlt">element</span> to Ca ratios in calcite and in solution] arise from variations in the ‘free’ fraction of total metal in aqueous solution (fm). Hence, differences in the preservation of each metal in calcite can be explained quantitatively by their complexation behaviour with aqueous NOM. Differences between inorganic Kd values and field measurements for metal partitioning into calcite occur where [free metal] ≪ [total metal] due to complexation reactions between metals and organic ligands (and potentially inorganic colloids). It follows that where fm ≈ 0, apparent inorganic Kd app values are also ≈0, but the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001GeCoA..65..435A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001GeCoA..65..435A"><span>Thermal effects on rare <span class="hlt">earth</span> <span class="hlt">element</span> and strontium isotope chemistry in single conodont <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Armstrong, H. A.; Pearson, D. G.; Griselin, M.</p> <p>2001-02-01</p> <p>A low-blank, high sensitivity isotope dilution, ICP-MS analytical technique has been used to obtain REE abundance data from single conodont <span class="hlt">elements</span> weighing as little as 5 μg. Sr isotopes can also be measured from the column eluants enabling Sr isotope ratios and REE abundance to be determined from the same dissolution. Results are comparable to published analyses comprising tens to hundreds of <span class="hlt">elements</span>. To study the effects of thermal metamorphism on REE and strontium mobility in conodonts, samples were selected from a single bed adjacent to a basaltic dyke and from the internationally used colour alteration index (CAI) "standard set." Our analyses span the range of CAI 1 to 8. Homogeneous REE patterns, "bell-shaped" shale-normalised REE patterns are observed across the range of CAI 1 to 6 in both sample sets. This pattern is interpreted as the result of adsorption during early diagenesis and could reflect original seawater chemistry. Above CAI 6 REE patterns become less predictable and perturbations from the typical REE pattern are likely to be due to the onset of apatite recrystallisation. Samples outside the contact aureole of the dyke have a mean 87Sr/ 86Sr ratio of 0.708165, within the broad range of published mid-Carboniferous seawater values. Our analysis indicates conodonts up to CAI 6 record primary geochemical signals that may be a proxy for ancient seawater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAESc.111..100L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAESc.111..100L"><span>Geological, rare <span class="hlt">earth</span> <span class="hlt">elemental</span> and isotopic constraints on the origin of the Banbanqiao Zn-Pb deposit, southwest China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Bo; Zhou, Jia-Xi; Huang, Zhi-Long; Yan, Zai-Fei; Bao, Guang-Ping; Sun, Hai-Rui</p> <p>2015-11-01</p> <p> <span class="hlt">elemental</span> and isotopic data suggest that the REE, C and S in the ore-forming fluids of the Banbanqiao deposit were mainly originated from the carbonate host rocks, while the Pb and O were primarily derived from radiogenic Pb- and 18O-depleted sources, which are most likely to be the underlying Proterozoic basement rocks. Studies on the geology, rare <span class="hlt">earth</span> <span class="hlt">elements</span> and isotope <span class="hlt">geochemistry</span> indicate that the Banbanqiao deposit is a carbonate-hosted, stratiform, anticline-controlled, epigenetic and high grade Zn-Pb deposit formed by <span class="hlt">elemental</span> compositions of mixed origin, and is a typical SYG-type deposit in the western Yangtze Block, southwest China.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JSAES..68..205A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JSAES..68..205A"><span>Sources of granite magmatism in the Embu Terrane (Ribeira Belt, Brazil): Neoproterozoic crust recycling constrained by <span class="hlt">elemental</span> and isotope (Sr-Nd-Pb) <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alves, Adriana; Janasi, Valdecir de Assis; Campos Neto, Mario da Costa</p> <p>2016-07-01</p> <p>Whole rock <span class="hlt">elemental</span> and Sr-Nd isotope <span class="hlt">geochemistry</span> and in situ K-feldspar Pb isotope <span class="hlt">geochemistry</span> were used to identify the sources involved in the genesis of Neoproterozoic granites from the Embu Terrane, Ribeira Belt, SE Brazil. Granite magmatism spanned over 200 Ma (810-580 Ma), and is dominated by crust-derived relatively low-T (850-750 °C, zircon saturation) biotite granites to biotite-muscovite granites. Two Cryogenian plutons show the least negative εNdt (-8 to -10) and highest mg# (30-40) of the whole set. Their compositions are strongly contrasted, implying distinct sources for the peraluminous (ASI ∼ 1.2) ∼660 Ma Serra do Quebra-Cangalha batholith (metasedimentary rocks from relatively young upper crust with high Rb/Sr and low Th/U) and the metaluminous (ASI = 0.96-1.00) ∼ 630 Ma Santa Catarina Granite. Although not typical, the geochemical signature of these granites may reflect a continental margin arc environment, and they could be products of a prolonged period of oceanic plate consumption started at ∼810 Ma. The predominant Ediacaran (595-580 Ma) plutons have a spread of compositions from biotite granites with SiO2 as low as ∼65% (e.g., Itapeti, Mauá, Sabaúna and Lagoinha granites) to fractionated muscovite granites (Mogi das Cruzes, Santa Branca and Guacuri granites; up to ∼75% SiO2). εNdT are characteristically negative (-12 to -18), with corresponding Nd TDM indicating sources with Paleoproterozoic mean crustal ages (2.0-2.5 Ga). The Guacuri and Santa Branca muscovite granites have the more negative εNdt, highest 87Sr/86Srt (0.714-0.717) and lowest 208Pb/206Pb and 207Pb/206Pb, consistent with an old metasedimentary source with low time-integrated Rb/Sr. However, a positive Nd-Sr isotope correlation is suggested by data from the other granites, and would be consistent with mixing between an older source predominant in the Mauá granite and a younger, high Rb/Sr source that is more abundant in the Lagoinha granite sample. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27609889','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27609889"><span>Highly siderophile <span class="hlt">elements</span> were stripped from <span class="hlt">Earth</span>'s mantle by iron sulfide segregation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rubie, David C; Laurenz, Vera; Jacobson, Seth A; Morbidelli, Alessandro; Palme, Herbert; Vogel, Antje K; Frost, Daniel J</p> <p>2016-09-09</p> <p>Highly siderophile <span class="hlt">elements</span> (HSEs) are strongly depleted in the bulk silicate <span class="hlt">Earth</span> (BSE) but are present in near-chondritic relative abundances. The conventional explanation is that the HSEs were stripped from the mantle by the segregation of metal during core formation but were added back in near-chondritic proportions by late accretion, after core formation had ceased. Here we show that metal-silicate equilibration and segregation during <span class="hlt">Earth</span>'s core formation actually increased HSE mantle concentrations because HSE partition coefficients are relatively low at the high pressures of core formation within <span class="hlt">Earth</span>. The pervasive exsolution and segregation of iron sulfide liquid from silicate liquid (the "Hadean matte") stripped magma oceans of HSEs during cooling and crystallization, before late accretion, and resulted in slightly suprachondritic palladium/iridium and ruthenium/iridium ratios.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.163..234D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.163..234D"><span>Thulium anomalies and rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns in meteorites and <span class="hlt">Earth</span>: Nebular fractionation and the nugget effect</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dauphas, Nicolas; Pourmand, Ali</p> <p>2015-08-01</p> <p>This study reports the bulk rare <span class="hlt">earth</span> <span class="hlt">element</span> (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 <span class="hlt">elemental</span> and isotopic ratios due to the nugget effect when the analyzed sample mass is limited and <span class="hlt">elements</span> 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 μm-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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991RSPSA.433..121S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991RSPSA.433..121S"><span>Analytical approach using KS <span class="hlt">elements</span> to near-<span class="hlt">earth</span> orbit predictions including drag</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharma, Ram Krishnan</p> <p>1991-04-01</p> <p>An analytical theory for the motion of near-<span class="hlt">earth</span> satellite orbits with the air drag effect is evolved in terms of the KS <span class="hlt">elements</span>, using an analytical oblate exponential atmospheric density model. Due to the symmetry of the KS <span class="hlt">element</span> equations, only one of the eight equations is integrated analytically to acquire the state vector at the close of each revolution. In the numerical studies performed, it is shown that after 100 revolutions, with a ballistic coefficient of 50, a maximum difference of 39 meters is found in the semimajor axis comparison for a very small eccentricity (0.001) instance having an initial perigee height of 391.425 km.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17837193','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17837193"><span>Bishop tuff revisited: new rare <span class="hlt">Earth</span> <span class="hlt">element</span> data consistent with crystal fractionation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cameron, K L</p> <p>1984-06-22</p> <p>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 <span class="hlt">earth</span> <span class="hlt">element</span> trend reported by Hildreth mimics the relations between groundmass glasses and whole rocks for allanite-bearing pumice. Differences in <span class="hlt">elemental</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28254037','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28254037"><span>Trace <span class="hlt">elements</span> and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in wet deposition of Lijiang, Mt. Yulong region, southeastern edge of the Tibetan Plateau.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guo, Junming; Kang, Shichang; Huang, Jie; Sillanpää, Mika; Niu, Hewen; Sun, Xuejun; He, Yuanqing; Wang, Shijing; Tripathee, Lekhendra</p> <p>2017-02-01</p> <p>In order to investigate the compositions and wet deposition fluxes of trace <span class="hlt">elements</span> and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in the precipitation of the southeastern edge of the Tibetan Plateau, 38 precipitation samples were collected from March to August in 2012 in an urban site of Lijiang city in the Mt. Yulong region. The concentrations of most trace <span class="hlt">elements</span> and REEs were higher during the non-monsoon season than during the monsoon season, indicating that the lower concentrations of trace <span class="hlt">elements</span> and REEs observed during monsoon had been influenced by the dilution effect of increased precipitation. The concentrations of trace <span class="hlt">elements</span> in the precipitation of Lijiang city were slightly higher than those observed in remote sites of the Tibetan Plateau but much lower than those observed in the metropolises of China, indicating that the atmospheric environment of Lijiang city was less influenced by anthropogenic emissions, and, as a consequence, the air quality was still relatively good. However, the results of enrichment factor and principal component analysis revealed that some anthropogenic activities (e.g., the increasing traffic emissions from the rapid development of tourism) were most likely important contributors to trace <span class="hlt">elements</span>, while the regional/local crustal sources rather than anthropogenic activities were the predominant contributors to the REEs in the wet deposition of Lijiang city. Our study was relevant not only for assessing the current status of the atmospheric environment in the Mt. Yulong region, but also for specific management actions to be implemented for the control of atmospheric inputs and the health of the environment for the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMDI11C2599K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMDI11C2599K"><span>A possible new host mineral of large-ion <span class="hlt">elements</span> in the <span class="hlt">Earth</span>'s deep interior</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawai, K.; Tsuchiya, T.</p> <p>2015-12-01</p> <p>The radiogenic heat production as well as the secular cooling is essential in order to better understand the thermal history and dynamics in the <span class="hlt">Earth</span>. Potassium is thought to be one of the important radioactive <span class="hlt">elements</span> in the <span class="hlt">Earth</span>'s interior. Although these <span class="hlt">elements</span> are concentrated in the continental and oceanic crusts due to chemical differentiations through partial melting at plate boundaries due to their large ion-radii, they have been considered to return into the deep mantle accompanied with subducting slab through time . However, since there are few studies on host minerals of potassium in the high P,T condition, it has yet to be clear how much and where host rocks of such radioactive <span class="hlt">elements</span> exist in the <span class="hlt">Earth</span>. Hence, it is important to understand the fate of the potassium-bearing phase subducted into the deep <span class="hlt">Earth</span>'s interior. Here we have studied the high-pressure stability and elasticity of KMg2Al5SiO12 hexagonal aluminous phase (K-Hex with three different size of cation cites, by means of the density functional computation method. Results indicate that the K-Hex phase remains mechanically stable up to 150 GPa and also energetically more stable than an isochemical form with the calcium-ferrite (K-CF) and calcium-titanate (K-CT) type structure with two different size of cation cites. In addition, when the spinel composition coexists with the K-hollandite (K-Hol) phase, which is ), which is considered to be able to host potassium the K-Hex phase becomes more stable than the K-Hol phase at pressures above ~27 GPa. These demonstrate that the Hex phase is substantially stable in the lower mantle, suggesting that it could be a potential host of potassium and other incompatible large-ion <span class="hlt">elements</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP12B..07E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP12B..07E"><span>Provenance of glacial tills in Ong Valley, Antarctica, inferred from quartz cathodoluminescence imaging, zircon U/Pb dating, and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Edwards, K. L.; Padilla, A. J.; Evans, A.; Morgan, D. J.; Balco, G.; Putkonen, J.; Bibby, T.</p> <p>2014-12-01</p> <p>An issue for interpreting exposure ages using cosmogenic nuclides is prior exposure (inheritance), especially for stable nuclides such as Ne-21. In this study we examine the reliability of provenance as a possible tool for determining the degree to which inheritance is an issue for a given sample. We use zircon U/Pb ages, quartz cathodoluminescence imaging, and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> from Antarctic glacial drifts and compare these to zircon, quartz, and trace <span class="hlt">elements</span> from local bedrock in order to determine the drifts' origins. This is potentially useful in Ong Valley in the Central Transantarctic Mountains, and likely elsewhere in Antarctica, as Antarctic glacial sediments are only derived either from sources that lie beneath the ice, where it likely had little prior exposure to cosmic rays, or from the relatively small amount of local, exposed bedrock, which would have inherited nuclides. Thus, sediment provenance is likely correlated with its inherited nuclide inventory. The bedrock of Ong Valley is composed of granite (Hope Granite, Granite Harbour Intrusives) and gneiss, and contains three glacial drifts. We collected samples from these three drifts and the surrounding bedrock. Cosmogenic nuclide dating using Ne-21 provides exposure ages for the quartz that can be used to constrain the timing of the glacier's retreat from the three sites. The accuracy of these three exposure ages depends on the prior (or inherited) exposure of the sediment and its sources. The use of the use of multiple methods for determining provenance allows us to compare the results and see if they reach the same conclusion. If cathodoluminescence imaging proves to be a reliable method for establishing provenance it would provide complementary information for cosmogenic nuclide dating, especially because quartz is significantly more abundant and we would be obtaining coupled provenance information and exposure ages from a single mineral.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11529577','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11529577"><span>Transport of rare <span class="hlt">earth</span> <span class="hlt">element</span>-tagged soil particles in response to thunderstorm runoff.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matisoff, G; Ketterer, M E; Wilson, C G; Layman, R; Whiting, P J</p> <p>2001-08-15</p> <p>The downslope transport of rare <span class="hlt">earth</span> <span class="hlt">element</span>-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 <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V53F3169Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V53F3169Y"><span>Halogen and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> in Mid-Ocean Ridge basalts from the Australian-Antarctic Ridge (AAR)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Y. S.; Seo, J. H.; Park, S. H.; Kim, T.</p> <p>2015-12-01</p> <p>Australian-Antarctic Ridge (AAR) is an extension of easternmost SE Indian Mid-Ocean Ridge (MOR).We collected volcanic glasses from the "in-axis" of the KR1 and KR2 MOR, and the overlapping zones of the KR1 MOR and the nearby seamounts ("KR1 mixing"). We determined trace and halogen <span class="hlt">elements</span> in the glasses. Halogen concentrations and its ratios in the glasses are important to understand the mantle metasomatism and volatile recycling. 52 of the collected glasses are "primitive" (higher than 6 wt% MgO), while 3 of them have rather "evolved" composition (MgO wt% of 1.72, 2.95 and 4.15). K2O concentrations and Th/Sc ratios in the glasses show a negative correlation with its MgO concentration. Incompatible <span class="hlt">element</span> ratios such as La/Sm are rather immobile during a magma differentiation so the ratios are important to understand mantle composition (Hofmann et al. 2003). La/Sm ratios in the glasses are 0.95 ~ 3.28 suggesting that the AAR basalts can be classified into T-MORB and E-MORB (Schilling et al., 1983). La/Sm ratios are well-correlated with incompatible <span class="hlt">elements</span> such as U, Ba, Nb, and negatively correlated with compatible <span class="hlt">elements</span> such as Sc, Eu2+, Mg. The AAR glasses contain detectable halogen <span class="hlt">elements</span>. The "KR1 mixing" glasses in halogen <span class="hlt">elements</span> are more abundant than "in-axis" the glasses. Cl is the least variable <span class="hlt">element</span> compared to the other halogens such as Br and I in the AAR. The "KR1 mixing" glasses have the largest variations of Br/Cl ratios compared to the "in-axis" glasses. The Cl/Br and Th/Sc ratios in the "in-axis" glasses and in the "KR1 mixing" glasses show positive and negative correlations, respectively. The Br-rich glasses in the "KR1 mixing" zone might be explained by a recycled Br-rich oceanic slab of paleo-subduction or by a hydrothermal alteration in the AAR. I composition in the glasses does not show a correlation other trace <span class="hlt">elements</span>. The K/Cl and K/Ti ratios in the AAR glasses are similar to the basalts from the Galapagos Spreading Center</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70031046','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70031046"><span>Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and surface water chemistry of the Bon Air coal, Franklin County, Cumberland Plateau, southeast Tennessee</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Shaver, S.A.; Hower, J.C.; Eble, C.F.; McLamb, E.D.; Kuers, K.</p> <p>2006-01-01</p> <p>Mean contents of trace <span class="hlt">elements</span> and ash in channel, bench-column, and dump samples of the abandoned Bon Air coal (Lower Pennsylvanian) in Franklin County, Tennessee are similar to Appalachian COALQUAL mean values, but are slightly lower for As, Fe, Hg, Mn, Na, Th, and U, and slightly higher for ash, Be, Cd, Co, Cr, REEs, Sr, and V, at the 95% confidence level. Compared to channel samples, dump sample means are slightly lower in chalcophile <span class="hlt">elements</span> (As, Cu, Fe, Ni, Pb, S, Sb, and V) and slightly higher in clay or heavy-mineral <span class="hlt">elements</span> (Al, K, Mn, REEs, Th, Ti, U, and Y), but at the 95% confidence level, only As and Fe are different. Consistent abundances of clay or heavy-mineral <span class="hlt">elements</span> in low-Br, high-S, high-ash benches that are relatively enriched in quartz and mire-to-levee species like Paralycopodites suggest trace <span class="hlt">elements</span> are largely fluvial in origin. Factor analysis loadings and correlation coefficients between <span class="hlt">elements</span> suggest that clays host most Al, Cr, K, Ti, and Th, significant Mn and V, and some Sc, U, Ba, and Ni. Heavy accessory minerals likely house most REEs and Y, lesser Sc, U, and Th, and minor Cr, Ni, and Ti. Pyrite appears to host As, some V and Ni, and perhaps some Cu, but Cu probably exists largely as chalcopyrite. Data suggest that organic debris houses most Be and some Ni and U, and that Pb and Sb occur as Pb-Sb sulfosalt(s) within organic matrix. Most Hg, and some Mn and Y, appear to be hosted by calcite, suggesting potential Hg remobilization from original pyrite, and Hg sorption by calcite, which may be important processes in abandoned coals. Most Co, Zn, Mo, and Cd, significant V and Ni, and some Mn probably occur in non-pyritic sulfides; Ba, Sr, and P are largely in crandallite-group phosphates. Selenium does not show organic or "clausthalite" affinities, but Se occurrence is otherwise unclear. Barium, Mn, Ni, Sc, U, and V, with strongly divided statistical affinities, likely occur subequally in multiple modes. For study area</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MMTE....3....6R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MMTE....3....6R"><span>A Study on Removal of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from U.S. Coal Byproducts by Ion Exchange</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rozelle, Peter L.; Khadilkar, Aditi B.; Pulati, Nuerxida; Soundarrajan, Nari; Klima, Mark S.; Mosser, Morgan M.; Miller, Charles E.; Pisupati, Sarma V.</p> <p>2016-03-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> are known to occur in low concentrations in U.S. coals and coal byproducts. These low concentrations may make rare <span class="hlt">earth</span> <span class="hlt">element</span> recovery from these materials unattractive, using only physical separation techniques. However, given the significant production of rare <span class="hlt">earths</span> through ion exchange extraction in China, two U.S. coal byproducts were examined for ion extraction, using ammonium sulfate, an ionic liquid, and a deep eutectic solvent as lixiviants. Extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in each case produced high recoveries of rare <span class="hlt">earth</span> <span class="hlt">elements</span> to the solution. This suggests that in at least the cases of the materials examined, U.S. coal byproducts may be technically suitable as REE ores. More work is required to establish economic suitability.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20298848','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20298848"><span>Distribution coefficients of 60 <span class="hlt">elements</span> on TODGA resin: application to Ca, Lu, Hf, U and Th isotope <span class="hlt">geochemistry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pourmand, Ali; Dauphas, Nicolas</p> <p>2010-05-15</p> <p>Batch equilibration experiments are conducted to measure the distribution coefficients (K(d)) of a large number of <span class="hlt">elements</span> in nitric, nitric plus hydrofluoric, and hydrochloric acids on Eichrom TODGA extraction chromatography resin. The K(d)s are used to devise a multi-<span class="hlt">element</span> extraction scheme for high-precision <span class="hlt">elemental</span> and isotopic analyses of Ca, Hf, Lu, Th and U in geological materials, using high-purity lithium metaborate (LiBO(2)) flux fusion that allows rapid digestion of even the most refractory materials. The fusion melt, dissolved in nitric acid, is directly loaded to a TODGA cartridge on a vacuum chamber for <span class="hlt">elemental</span> separation. An Ln-Spec cartridge is used in tandem with TODGA for Lu purification. The entire procedure, from flux digestion to preparation for isotopic analysis, can be completed in a day. The accuracy of the proposed technique is tested by measuring the concentrations of Ca (standard bracketing), Hf, Lu, Th and U (isotope dilution), and the isotopic composition of Hf in geostandards (USNM3529, BCR-2, BHVO-1, AGV-1 and AGV-2). All measurements are in excellent agreement with recommended literature values, demonstrating the effectiveness of the proposed analytical procedure and the versatility of TODGA resin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E6221Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E6221Z"><span>The Environmental <span class="hlt">Geochemistry</span> of Trace <span class="hlt">Elements</span> and Naturally Radionuclides in a Coal Gangue Brick-Making Plant</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Chuncai; Liu, Guijian; Cheng, Siwei; Fang, Ting; Lam, Paul K. S.</p> <p>2014-08-01</p> <p>An investigation focused on the transformation and distribution behaviors of trace <span class="hlt">elements</span> and natural radionuclides around a coal gangue brick plant was conducted. Simultaneous sampling of coal gangue, brick, fly ash and flue gas were implemented. Soil, soybean and earthworm samples around the brick plant were also collected for comprehensive ecological assessment. During the firing process, trace <span class="hlt">elements</span> were released and redistributed in the brick, fly ash and the flue gas. <span class="hlt">Elements</span> can be divided into two groups according to their releasing characteristics, high volatile <span class="hlt">elements</span> (release ratio higher than 30%) are represented by Cd, Cu, Hg, Pb, Se and Sn, which emitted mainly in flue gas that would travel and deposit at the northeast and southwest direction around the brick plant. Cadmium, Ni and Pb are bio-accumulated in the soybean grown on the study area, which indicates potential health impacts in case of human consumption. The high activity of natural radionuclides in the atmosphere around the plant as well as in the made-up bricks will increase the health risk of respiratory system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820048232&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2527%2527rare%2Bearths%2527%2527','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820048232&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2527%2527rare%2Bearths%2527%2527"><span>Complementary rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns in unique achondrites, such as ALHA 77005 and shergottites, and in the <span class="hlt">earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ma, M.-S.; Schmitt, R. A.; Laul, J. C.</p> <p>1982-01-01</p> <p>Abundances of major, minor, and trace <span class="hlt">elements</span> are determined in the Antarctic achondrite Allan Hills (ALHA) 77005 via sequential instrumental and radiochemical neutron activation analysis. The rare <span class="hlt">earth</span> <span class="hlt">element</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C11B0358K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C11B0358K"><span>Siku: A Sea Ice Discrete <span class="hlt">Element</span> Method Model on a Spherical <span class="hlt">Earth</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kulchitsky, A. V.; Hutchings, J. K.; Johnson, J.</p> <p>2014-12-01</p> <p>Offshore oil and gas exploration and production activities in the Beaufort and Chukchi Seas can be significantly and adversely affected by sea ice. In the event of an oil spill, sea ice complicates the tracking of ice/oil trajectories and can hinder cleanup operations. There is a need for a sea ice dynamics model that can accurately simulate ice pack deformation and failure to improve the ability to track ice/oil trajectories and support oil response operations. A discrete <span class="hlt">element</span> method (DEM) model, where each ice floe is represented by discrete <span class="hlt">elements</span> that are initially bonded (frozen) together will be used to address the difficulty continuum modeling approaches have with representing discrete phenomena in sea ice, such as the formation of leads and ridges. Each discrete <span class="hlt">element</span> in the DEM is a rigid body driven by environmental forcing (wind, current and Coriolis forces) and interaction forces with other discrete <span class="hlt">elements</span> (compression, shear, tension, bond rupture and regrowth). We introduce a new DEM model ``Siku'', currently under development, to simulate ice drift of an ice floe on a spherical <span class="hlt">Earth</span>. We will present initial free-drift results. Siku is focused on improving sea ice interaction mechanics and providing an accurate geometrical representation needed for basin scale and regional simulations. Upon completion, Siku will be an open source GNU GPL licensed user friendly program with embedded python capability for setting up simulations "scenarios" and coupling with other models to provide forcing fields. We use a unique quaternion representation for position and orientation of polygon sea-ice <span class="hlt">elements</span> that use a second order integration scheme of sea-ice <span class="hlt">element</span> motion on the <span class="hlt">Earth</span>'s sphere that does not depend on the location of the <span class="hlt">element</span> and, hence, avoids numerical problems near the pole.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA545604','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA545604"><span>Mining and Exploitation of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Africa as an Engagement Strategy in US Africa Command</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2011-06-17</p> <p>Globalsecurity.org, 2010, 2. 3 Geology.com, “REE Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> and their Uses,” Geology.com, http://geology.com/ articles /rare-<span class="hlt">earth-elements</span>/ (accessed...controversy for decades.36 Jasper, in his article “Engineered Extinction” specifically mentions U.S. rare <span class="hlt">earth</span> mining. He details the impact that...35 Justin Rohrlich, “How China Came to Dominate the Rare <span class="hlt">Earths</span> Market,” December 29, 2010, http://www.minyanville.com/businessmarkets/ articles</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999RvGeo..37..249O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999RvGeo..37..249O"><span>Molecular environmental <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>O'Day, Peggy A.</p> <p>1999-05-01</p> <p>The chemistry, mobility, and bioavailability of contaminant species in the natural environment are controlled by reactions that occur in and among solid, aqueous, and gas phases. These reactions are varied and complex, involving changes in chemical form and mass transfer among inorganic, organic, and biochemical species. The field of molecular environmental <span class="hlt">geochemistry</span> seeks to apply spectroscopic and microscopic probes to the mechanistic understanding of environmentally relevant chemical processes, particularly those involving contaminants and <span class="hlt">Earth</span> materials. In general, empirical geochemical models have been shown to lack uniqueness and adequate predictive capability, even in relatively simple systems. Molecular geochemical tools, when coupled with macroscopic measurements, can provide the level of chemical detail required for the credible extrapolation of contaminant reactivity and bioavailability over ranges of temperature, pressure, and composition. This review focuses on recent advances in the understanding of molecular chemistry and reaction mechanisms at mineral surfaces and mineral-fluid interfaces spurred by the application of new spectroscopies and microscopies. These methods, such as synchrotron X-ray absorption and scattering techniques, vibrational and resonance spectroscopies, and scanning probe microscopies, provide direct chemical information that can elucidate molecular mechanisms, including <span class="hlt">element</span> speciation, ligand coordination and oxidation state, structural arrangement and crystallinity on different scales, and physical morphology and topography of surfaces. Nonvacuum techniques that allow examination of reactions in situ (i.e., with water or fluids present) and in real time provide direct links between molecular structure and reactivity and measurements of kinetic rates or thermodynamic properties. Applications of these diverse probes to laboratory model systems have provided fundamental insight into inorganic and organic reactions at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23548400','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23548400"><span>Bioleaching of rare <span class="hlt">earth</span> and radioactive <span class="hlt">elements</span> from red mud using Penicillium tricolor RM-10.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qu, Yang; Lian, Bin</p> <p>2013-05-01</p> <p>The aim of this work is to investigate biological leaching of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and radioactive <span class="hlt">elements</span> 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 <span class="hlt">elements</span>. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790055121&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790055121&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Drare%2Bearth"><span>Experimental partitioning of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and scandium among armalcolite, ilmenite, olivine and mare basalt liquid</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Irving, A. J.; Merrill, R. B.; Singleton, D. E.</p> <p>1978-01-01</p> <p>An experimental study was carried out to measure partition coefficients for two rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">element</span> 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 <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011932','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011932"><span>Minor and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of volcanic rocks dredged from the Galapagos spreading center: role of crystal fractionation and mantle heterogeneity.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Clague, D.A.; Frey, F.A.; Thompson, G.; Rindge, S.</p> <p>1981-01-01</p> <p>A wide range of rock types (abyssal tholeiite, Fe-Ti-rich basalt, andesite, and rhyodacite) were dredged from near 95oW and 85oW on the Galapagos spreading center. Computer modeling of major <span class="hlt">element</span> compositions has shown that these rocks could be derived from common parental magmas by successive degrees of fractional crystallization. However, the P2O5/K2O ratio implies distinct mantle source compositions for the two areas. These source regions also have different rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) abundance patterns. The sequence of fractionated lavas differs for the two areas and indicates earlier fractionation of apatite and titanomagnetite in the lavas from 95oW. The mantle source regions for these two areas are interpreted to be depleted in incompatible (and volatile?) <span class="hlt">elements</span>, although the source region beneath 95oW is less severely depleted in La and K. -Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.3552S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.3552S"><span>Assessment of groundwater dynamics by applying rare <span class="hlt">earth</span> <span class="hlt">elements</span> and stable isotopes &ndash; the case of the Tiberias Basin, Jordan Valley.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siebert, Christian; Möller, Peter; Rödiger, Tino; Al-Raggad, Marwan; Magri, Fabien</p> <p>2015-04-01</p> <p>The Tiberias basin, situated in the northern part of the Jordan-Dead Sea Transform Valley, is hydraulically connected to the surrounding aquifers of Cretaceous to Cenozoic age. As a result of the local erosion base, the basin hosts Lake Tiberias, recharged mainly by the Upper Jordan River and by fresh groundwater from the Galilee and Golan Heights. However, variably ascending deep-seated brines enhance the chlorinity of the lake to about 250-280 mg/l. In addition to these hot brines, also hot fresh waters emerge on surface, particularly to both sides of the Yarmouk gorge, SE of the basin. Investigation of rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns and stable isotopes of water and sulfur, in combination with major <span class="hlt">elements</span> reveal, that the gorge acts at least partially as a water divide between north and south with enhanced hydraulic conductivity along its axis. Although there are no geological evidences given, we suppose a swarm of hydraulic active fractures/faults parallel to the Lower Yarmouk gorge axis, which force the upward movement of hot fluids, as also suggested by numerical modeling. Additionally, these faults may channel SW-oriented groundwater flow, which has its origin in the Syrian Hauran Plateau. Although exercised in the Tiberias Basin, the application of trace and major <span class="hlt">element</span> <span class="hlt">geochemistry</span> in combination with stable isotopes allows analyzing (supra-) regional groundwater movements. This method is even more relevant in areas with either limited access to recharge areas or boreholes along proposed flow-paths and particularly in areas suffering from data scarcity and poor infrastructure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16913112','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16913112"><span>Multi-<span class="hlt">element</span> including rare <span class="hlt">earth</span> content of lichens, bark, soils, and waste following industrial closure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rusu, Ana-Maria; Chimonides, P D James; Jones, Gary C; Garcia-Sanchez, Raquel; Purvis, O William</p> <p>2006-08-01</p> <p>The fate of rare <span class="hlt">earth</span> and other rare <span class="hlt">elements</span> entering the environment is largely unknown. The lichen Hypogymnia physodes was transplanted over a 40 km long transect centered on a major metallurgical waste dump close to the Zlatna town center two weeks after smelter closure. Lichens, bark, soil, and waste dump materials were analyzed for 56 <span class="hlt">elements</span> (including REE). Lichen and bark multi-<span class="hlt">element</span> compositions were alike, reflecting fixation of <span class="hlt">elements</span> of environmental concern and the ability for tree canopies to concentrate substances leading to enhanced deposition to both lichens and bark. Higher REE enrichment in lichens than in soil confirm efficient fixation in lichens. The negative europium anomaly in lichens and soil, similar to that in upper crust, confirm a strong crustal influence on lichen signatures across the transect area. Multi-<span class="hlt">element</span> analysis supports the view that epiphytic lichens, unlike trees, are not influenced by lower groundwater, and they are excellent indicators for REE and other rare <span class="hlt">elements</span> entering the surface environment, difficult to detect by conventional means.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1261279-quantification-rare-earth-elements-using-laser-induced-breakdown-spectroscopy','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1261279-quantification-rare-earth-elements-using-laser-induced-breakdown-spectroscopy"><span>Quantification of rare <span class="hlt">earth</span> <span class="hlt">elements</span> using laser-induced breakdown spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Martin, Madhavi; Martin, Rodger C.; Allman, Steve; ...</p> <p>2015-10-21</p> <p>In this paper, a study of the optical emission as a function of concentration of laser-ablated yttrium (Y) and of six rare <span class="hlt">earth</span> <span class="hlt">elements</span>, 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 <span class="hlt">elements</span> at several concentrations. Each <span class="hlt">element</span> (in oxide form) was mixed in the graphite matrix in percentages rangingmore » 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 <span class="hlt">elements</span> in equal oxide masses to determine if we can identify the <span class="hlt">elemental</span> 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. Finally, 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 <span class="hlt">elements</span> in high-burnup nuclear reactor fuel.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1261279','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1261279"><span>Quantification of rare <span class="hlt">earth</span> <span class="hlt">elements</span> using laser-induced breakdown spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Martin, Madhavi; Martin, Rodger C.; Allman, Steve; Brice, Deanne; Wymore, Ann; Andre, Nicolas</p> <p>2015-10-21</p> <p>In this paper, a study of the optical emission as a function of concentration of laser-ablated yttrium (Y) and of six rare <span class="hlt">earth</span> <span class="hlt">elements</span>, 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 <span class="hlt">elements</span> at several concentrations. Each <span class="hlt">element</span> (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 <span class="hlt">elements</span> in equal oxide masses to determine if we can identify the <span class="hlt">elemental</span> 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. Finally, 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 <span class="hlt">elements</span> in high-burnup nuclear reactor fuel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AcSpe.114...65M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AcSpe.114...65M"><span>Quantification of rare <span class="hlt">earth</span> <span class="hlt">elements</span> using laser-induced breakdown spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Madhavi; Martin, Rodger C.; Allman, Steve; Brice, Deanne; Wymore, Ann; Andre, Nicolas</p> <p>2015-12-01</p> <p>A study of the optical emission as a function of concentration of laser-ablated yttrium (Y) and of six rare <span class="hlt">earth</span> <span class="hlt">elements</span>, 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 <span class="hlt">elements</span> at several concentrations. Each <span class="hlt">element</span> (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 <span class="hlt">elements</span> in equal oxide masses to determine if we can identify the <span class="hlt">elemental</span> 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 <span class="hlt">elements</span> in high-burnup nuclear reactor fuel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1265838','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1265838"><span>Spectral Analysis of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> using Laser-Induced Breakdown Spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Martin, Madhavi Z; Fox, Dr. Richard V; Miziolek, Andrzej W; DeLucia, Frank C; Andre, Nicolas O</p> <p>2015-01-01</p> <p>There is growing interest in rapid analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> magnets are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1265542','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1265542"><span>Spectral Analysis of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> using Laser-Induced Breakdown Spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Martin, Madhavi Z; Fox, Dr. Richard V; Miziolek, Andrzej W; DeLucia, Frank C; Andre, Nicolas O</p> <p>2015-01-01</p> <p>There is growing interest in rapid analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 real-world complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> magnets are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24681591','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24681591"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> recycling from waste phosphor by dual hydrochloric acid dissolution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Hu; Zhang, Shengen; Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin; Volinsky, Alex A</p> <p>2014-05-15</p> <p>This paper is a comparative study of recycling rare <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> 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 <span class="hlt">earth</span> <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510494','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510494"><span>Geochemical fractions of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soil around a mine tailing in Baotou, China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Lingqing; Liang, Tao</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> 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 <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China’s largest rare <span class="hlt">earth</span> 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 <span class="hlt">elements</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9482E..0GM','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9482E..0GM"><span>Spectral analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> using laser-induced breakdown spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Madhavi Z.; Fox, Robert V.; Miziolek, Andrzej W.; DeLucia, Frank C.; André, Nicolas</p> <p>2015-06-01</p> <p>There is growing interest in rapid analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> magnets are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1196551','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1196551"><span>Spectral Analysis of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> using Laser-Induced Breakdown Spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Madhavi Z. Martin; Robert V. Fox; Andrzej W. Miziolek; Frank C. DeLucia, Jr.; Nicolas Andre</p> <p>2001-05-01</p> <p>There is growing interest in rapid analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> magnets are presented.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26198417','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26198417"><span>Geochemical fractions of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soil around a mine tailing in Baotou, China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Lingqing; Liang, Tao</p> <p>2015-07-22</p> <p>Rare <span class="hlt">earth</span> 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 <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China's largest rare <span class="hlt">earth</span> 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 <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011NatGe...4..535K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011NatGe...4..535K"><span>Deep-sea mud in the Pacific Ocean as a potential resource for rare-<span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kato, Yasuhiro; Fujinaga, Koichiro; Nakamura, Kentaro; Takaya, Yutaro; Kitamura, Kenichi; Ohta, Junichiro; Toda, Ryuichi; Nakashima, Takuya; Iwamori, Hikaru</p> <p>2011-08-01</p> <p>World demand for rare-<span class="hlt">earth</span> <span class="hlt">elements</span> and the metal yttrium--which are crucial for novel electronic equipment and green-energy technologies--is increasing rapidly. Several types of seafloor sediment harbour high concentrations of these <span class="hlt">elements</span>. However, seafloor sediments have not been regarded as a rare-<span class="hlt">earth</span> <span class="hlt">element</span> and yttrium resource, because data on the spatial distribution of these deposits are insufficient. Here, we report measurements of the <span class="hlt">elemental</span> composition of over 2,000 seafloor sediments, sampled at depth intervals of around one metre, at 78 sites that cover a large part of the Pacific Ocean. We show that deep-sea mud contains high concentrations of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> and yttrium at numerous sites throughout the eastern South and central North Pacific. We estimate that an area of just one square kilometre, surrounding one of the sampling sites, could provide one-fifth of the current annual world consumption of these <span class="hlt">elements</span>. Uptake of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> and yttrium by mineral phases such as hydrothermal iron-oxyhydroxides and phillipsite seems to be responsible for their high concentration. We show that rare-<span class="hlt">earth</span> <span class="hlt">elements</span> and yttrium are readily recovered from the mud by simple acid leaching, and suggest that deep-sea mud constitutes a highly promising huge resource for these <span class="hlt">elements</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022811','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022811"><span>Major, trace <span class="hlt">element</span> and isotope <span class="hlt">geochemistry</span> (Sr-Nd-Pb) of interplinian magmas from Mt. Somma-Vesuvius (Southern Italy)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Somma, R.; Ayuso, R.A.; de Vivo, B.; Rolandi, G.</p> <p>2001-01-01</p> <p>Major, trace <span class="hlt">element</span> and isotopic (Sr, Nd, Pb) data are reported for representative samples of interplinian (Protohistoric, Ancient Historic and Medieval Formations) activity of Mt. Somma-Vesuvius volcano during the last 3500 years. Tephra and lavas exhibit significant major, trace <span class="hlt">element</span> and isotopic variations. Integration of these data with those obtained by previous studies on the older Somma suites and on the latest activity, allows to better trace a complete petrological and geochemical evolution of the Mt. Somma-Vesuvius magmatism. Three main groups of rocks are recognized. A first group is older than 12.000 yrs, and includes effusive-explosive activity of Mt. Somma. The second group (8000-2700 yrs B.P.) includes the products emitted by the Ottaviano (8000 yrs. B.P.) and Avellino (3550 yrs B.P.) plinian eruptions and the interplinian activity associated with the Protohistoric Formation. Ancient Historic Formation (79-472 A.D.), Medieval Formation (472-1139 A.D.) and Recent interplinian activity (1631-1944 A.D.) belong to the third group of activity (79-1944 A.D.). The three groups of rocks display distinct positive trends of alkalis vs. silica, which become increasingly steeper with age. In the first group there is an increase in silica and alkalis with time, whereas an opposite tendency is observed in the two younger groups. Systematic variations are also evident among the incompatible (Pb, Zr, Hf, Ta, Th, U, Nb, Rb, Cs, Ba) and compatible <span class="hlt">elements</span> (Sr, Co, Cr). REE document variable degrees of fractionation, with recent activity displaying higher La/Yb ratios than Medieval and Ancient Historic products with the same degree of evolution. N-MORB normalized multi-<span class="hlt">element</span> diagrams for interplinian rocks show enrichment in Rb, Th, Nb, Zr and Sm (> *10 N-MORB). Sr isotope ratios are variable, with Protohistoric rocks displaying 87Sr/86Sr= 0.70711-0.70810, Ancient Historic 87Sr/86Sr=0.70665-0.70729, and Medieval 87Sr/86Sr=0.70685-0.70803. Neodymium isotopic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985GeCoA..49.1875W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985GeCoA..49.1875W"><span>Isotope and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of sediments from the Barbados Ridge-Demerara Plain region, Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>White, William M.; Dupré, Bernard; Vidal, Philippe</p> <p>1985-09-01</p> <p>Twenty-four piston core sediment samples and 13 sediments and 3 basalts from DSDP Leg 78 Site 543 were analyzed for Sr, Nd and Pb isotopic compositions. The results show sediment with highly radiogenic Pb 206Pb /204Pb up to 19.8) and rather radiogenic Sr and unradiogenic Nd has been deposited in the region since the Cretaceous. The source of this sediment is probably the Archean Guiana Highland, which is drained by the Orinoco River. Pb and Sr isotopic compositions and sediment thickness decrease and 143Nd /144Nd increases northward due to a decrease in turbiditic component. This decrease is partly due to the damming action of basement ridges. Rare <span class="hlt">earth</span> concentrations in the sediments are somewhat low, due to the abundance of detrital and biogenic components in the sediment and rapid sedimentation rates. Both positive and negative Ce anomalies occur in the surface sediments, but only positive Ce anomalies occur in the Site 543 sediments. It is unlikely that sediment subducted to the source region of Lesser Antilles arc magmas could be the cause of negative Ce anomalies in those magmas. Isotopic compositions of Site 543 basalts show some effect of contamination by seawater-basalt reaction products and sediments. Beyond this, however, they are typical of "normal" depleted MORB.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUSMPP53A..06L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUSMPP53A..06L"><span>Late Holocene Multiproxy Record (Palynology, Stable Isotope and Multi-<span class="hlt">Element</span> <span class="hlt">Geochemistry</span>) of Lake Santa Maria del Oro, Western Mesoamerica.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lozano, S.; Caballero, M.; Rodriguez, A.; Roy, P.; Sosa, S.</p> <p>2007-05-01</p> <p>We present the palynological, stable isotope and major <span class="hlt">element</span> (ITRAX X-Ray fluorescence) data from a 850-cm sediment sequence from the deepest part of lake Santa María del Oro (SMO) in order to document changes in the climatic and limnological conditions and in the vegetation for the last ca. 5000 yr. SMO is a crater lake of (750 m asl, 2 km diam.) located in a tropical sub-humid climate (1250 mm/yr, average annual temperature 21° C) at the transition between the temperate central Mexican highlands and the arid northern regions. Tropical deciduous forests which loose their leaves for 8 months in a year and the tropical oak forests are the main plant communities in the lake catchments. The western part of Mesoamerica is the cradle of maize (Zea mays ssp. mays ) agriculture; this region is probably one of the two centers of maize domestication based on the presence of one of its closets wild relative teosinte (Zea mays ssp. parviglumis ). Chronology was established with 8 AMS radiocarbon dates. Sediments are finely laminated, with some intervals dominated by black and brown clayey silt and others by brown clayey silt and calcareous silt. In some levels, laminae are characterized by silts and fine sands. Authigenic carbonate laminations are formed during the summer season, when the highest temperatures are reached in the area. Throughout the pollen analysis, teosinte pollen and maize pollen was recorded. The major <span class="hlt">element</span> concentration (Ca and Ti) in the bulk sediments was analyzed by ITRAX multi-<span class="hlt">element</span> scanner and the isotopic data (δ13C and δ18O) in authigenic carbonates by mass spectrometer. Ca and Ti ITRAX intensities were calibrated to mass % by using the linear relationship between ITRAX intensity and mass % obtained through conventional XRF analysis. Preliminary pollen data of SMO sediments indicates abundant pollen of teosinte from ca. 2000 to 100 BC and maize presence at ca. 1300 BC and ca. 900 BC along with high charcoal particle concentrations</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9828W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9828W"><span>Enhanced phytoextraction of germanium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> - a rhizosphere-based approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wiche, Oliver</p> <p>2016-04-01</p> <p>Germanium (Ge) and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are economically valuable raw materials that have become an integral part of our modern high tech society. While most of these <span class="hlt">elements</span> are not actually rare in terms of general amounts in the <span class="hlt">earth</span>'s crust, they are rarely found in sufficient abundances in single locations for their mining to be economically viable. The average concentration of Ge in soils is estimated at 1.6 μg g-1. The REEs comprise a group of 16 <span class="hlt">elements</span> including La, the group of lanthanides and Y that are abundant in the <span class="hlt">earth</span> crust with concentrations varying from 35 μg g-1 (La), 40 μg g-1 (Nd), 6 μg g-1 (Gd) and 3.5 μg g-1 (Er) to 0.5 μg g-1 in Tm. Thus, a promising chance to improve supply of these <span class="hlt">elements</span> could be phytomining. Unfortunately, bioavailability of Ge and REEs in soils appears to be low, in particular in neutral or alkaline soils. A sequential dissolution analysis of 120 soil samples taken from the A-horizons of soils in the area of Freiberg (Saxony, Germany) revealed that only 0.2% of total Ge and about 0.5% of La, Nd, Gd and Er of bulk concentrations were easily accessible by leaching with NH4-acetate (pH 7). Most of the investigated <span class="hlt">elements</span> were bound to Fe-/Mn-oxides and silicates and were therefore only poorly available for plant uptake. Here we report an environmentally friendly approach for enhanced phytoextraction of Ge and REEs from soils using mixed cultures of plant species with efficient mechanisms for the acquisition of nutrients in the rhizosphere. The rhizosphere is characterized as the zone in soil sourrounding a plant root that consists of a gradient in chemical, physical and biological soil properties driven by rhizodeposits like carboxylates and protons. Some species like white lupin (Lupinus albus) are able to excrete large amounts of organic acid anions(predominantly citrate and malate) and show a particularly high potential for the acidification of the rhizosphere. In our experiments, mixed cultures</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhSRv...1...62S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhSRv...1...62S"><span>Neutron Activation Analysis of the Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) - With Emphasis on Geological Materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stosch, Heinz-Günter</p> <p>2016-08-01</p> <p>Neutron activation analysis (NAA) has been the analytical method of choice for rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) analysis from the early 1960s through the 1980s. At that time, irradiation facilitieswere widely available and fairly easily accessible. The development of high-resolution gamma-ray detectors in the mid-1960s eliminated, formany applications, the need for chemical separation of the REE from the matrix material, making NAA a reliable and effective analytical tool. While not as precise as isotopedilution mass spectrometry, NAA was competitive by being sensitive for the analysis of about half of the rare <span class="hlt">earths</span> (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu). The development of inductively coupled plasma mass spectrometry since the 1980s, together with decommissioning of research reactors and the lack of installation of new ones in Europe and North America has led to the rapid decline of NAA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5346738','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5346738"><span>Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of volcanic gases and particles from 1983--1984 eruptive episodes of Kilauea volcano</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Crowe, B.M.; Finnegan, D.L.; Zoller, W.H.; Boynton, W.V.</p> <p>1987-12-10</p> <p>Compositional data have been obtained for volcanic gases and particles collected from fume emitted at the Pu'u O'o vent on the east rift zone of Kilauea volcano. The samples were collected by pumping fume through a filter pack system consisting of a front stage particulate filter followed by four base-treated filters (/sup 7/LiOH). Particles and condensed phases are trapped on the particulate filter, and acidic gases are collected on the treated filters. The filters are analyzed for 30 <span class="hlt">elements</span> by instrumental neutron activation analysis. Fume samples were collected from the Pu'u O'o vent for two eruptive episodes: (1) 7 days after episode 11 (cooling vent samples) and (2) the stage of episode 13 (active vent samples).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23896401','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23896401"><span>Major and minor <span class="hlt">element</span> <span class="hlt">geochemistry</span> of deep-sea sediments in the Azores Platform and southern seamount region.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Palma, Carla; Oliveira, Anabela; Valença, Manuela; Cascalho, João; Pereira, Eduarda; Lillebø, Ana I; Duarte, Armando C; Pinto de Abreu, Manuel</p> <p>2013-10-15</p> <p>The Azores Platform and the Irving and Great Meteor seamounts south of the archipelago (38°N-29°N) have rarely been studied geochemically, a fact which is surprising given that they represent the south-eastern limit of region V outlined in the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR Convention). The main aim of the present work was therefore to characterise the spatial variability of major and minor <span class="hlt">elements</span> in deep-sea sediment cores from these two regions. XRD and geochemical analyses revealed that whereas the Azores Platform sediments are composed of a mixture of biogenic and detrital volcanic material, those at the seamounts are characterised by carbonated biogenic remains. The latter sediments were found to contain very low amounts of volcanic or hydrothermal detrital material, being almost entirely comprised of CaCO3 (more than 80%).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1110711L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1110711L"><span>Biological availability and environmental behaviour of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in soils of Hesse, Central Germany</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loell, M.; Duering, R.-A.; Felix-Henningsen, P.</p> <p>2009-04-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) comprise a group of 17 transition metals with very similar chemical and physical properties. They include the <span class="hlt">elements</span> scandium (Sc), yttrium (Y) and lanthanum (La) and the 14 <span class="hlt">elements</span> (cerium to lutetium) that follow La in the periodic table. Their average abundance in the <span class="hlt">earth</span>'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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V33C3117C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V33C3117C"><span>Major and Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span> of the Mafic Magmatic Rocks from the Betul Mobile Belt, Central Indian Tectonic Zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choudhury, A.; Ghatak, A.</p> <p>2015-12-01</p> <p>Peninsular shield of India is composed of several Archaean cratons bordered by Proterozoic mobile belts which amalgamated the Archaean cratons and helped in the growth of the Indian subcontinent. The ENE-WSW trending Central Indian Tectonic Zone (CITZ) is one such important mobile belt which sutures the Bundelkhand and the Aravalli craton in the north and Bastar, Singhbhum and Dharwar cratons in the south. The CITZ is a collection of lithotectonic terranes ranging in age from Archaean to recent and comprises supracrustal belts, granulite belts, shear zones and felsic-mafic magmatic rocks. The Betul belt is characterized by a litho-package of plutonic magmatic rocks, volcano-sedimentary rocks, bimodal volcanics and associated base metal sulphide mineralization. The petrological, geochemical and geochronological evolution of the mafic magmatic rocks has significance in our understanding of Proterozoic crustal evolution in central India. Here we report major and trace <span class="hlt">element</span> concentrations of 14 mafic samples (basaslts, gabbors, pyroxenites and dolerites) in an attempt to classify, characterise and suggest a spatial and temporal evolution of the mafic magmatic rocks of the Betul mobile belt vis-à-vis CITZ. Traditionally these rocks have been classified as being calc-alkaline rocks, related to arc volcanism and rift tectonics. We have divided these rocks into those have a positive Europium anomaly and those having a negative Europium anomaly to better understand the source and the contaminant for these rocks. We find characterisitic difference specifically in the trace <span class="hlt">element</span> ratios and concentrations of the rocks with +Eu anomaly [La=10.69ppm; LaN/YbN=3.65] and those with -Eu anomaly [La=27.59; LaN/YbN=8.86]. Based on these data we propose that the Betul mafic rocks may have been derived from an enriched mantle source that experienced contamination from the lower continental crust or sub-continental lithosphere prior to eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT.........1E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT.........1E"><span>Investigation of recovery and recycling of rare <span class="hlt">earth</span> <span class="hlt">elements</span> from waste fluorescent lamp phosphors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eduafo, Patrick Max</p> <p></p> <p>Characterization techniques and experimental measurements were used to evaluate a process for recycling rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) from spent fluorescent lamp phosphors. QEMSCAN analysis revealed that over 60% of the rare <span class="hlt">earth</span> bearing minerals was less than 10 microm. A representative sample of the as-received feed contained 14.59 wt% total rare <span class="hlt">earth</span> <span class="hlt">elements</span> (TREE) and upon sieving to below 75 microm, the grade increased to 19.60 wt% REE with 98.75% recovery. Based on experimental work, a new process for extracting the chief REEs from end of life fluorescent lamps has been developed. The proposed flowsheet employs a three-stage leaching and precipitation process for selective extraction and recovery of the REEs. Hydrochloric acid was used as lixiviant in batch leach experiments on the phosphor powder. The maximum extraction obtained was 100% for both yttrium and europium under the following leaching conditions: 2.5 M HCl, 70°C, 1 hour, 180 g/L and 600 rpm. However, the solubility of cerium, lanthanum and terbium remained low at these conditions. Kinetic data of the leaching of yttrium and europium showed best fit to the logarithmic rate expression of the empirical model of leaching. Activation energy was calculated to be 77.49 kJ/mol for Y and 72.75 kJ/mol for Eu in the temperature range of 298 to 343 K. Precipitation tests demonstrate that at least 50% excess the stoichiometric amount of oxalic acid is needed to recover yttrium and europium efficiently to produce a pure (Y, Eu) mixed oxide. Total recovery of the REEs was achieved even at very low pH or without any base added. Over 99% pure mixed rare <span class="hlt">earth</span> oxide at 99% recovery has been attained. An economic assessment of the developed process using operating and capital cost have be undertaken and based on the analysis of the three economic scenarios, two are economic and one is non-economic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002835','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002835"><span>Origin of Volatiles in <span class="hlt">Earth</span>: Indigenous Versus Exogenous Sources Based on Highly Siderophile, Volatile Siderophile, and Light Volatile <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, K.; Danielson, L.; Pando, K. M.; Marin, N.; Nickodem, K.</p> <p>2015-01-01</p> <p>Origin of <span class="hlt">Earth</span>'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 <span class="hlt">Earth</span> 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 <span class="hlt">elements</span> that suggests <span class="hlt">Earth</span>'s volatiles were acquired during accretion and did not require additional sources after differentiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AnGeo..32.1477B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AnGeo..32.1477B"><span>On the origin of falling-tone chorus <span class="hlt">elements</span> in <span class="hlt">Earth</span>'s inner magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Breuillard, H.; Agapitov, O.; Artemyev, A.; Krasnoselskikh, V.; Le Contel, O.; Cully, C. M.; Angelopoulos, V.; Zaliznyak, Y.; Rolland, G.</p> <p>2014-12-01</p> <p>Generation of extremely/very low frequency (ELF/VLF) chorus waves in <span class="hlt">Earth</span>'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 <span class="hlt">elements</span> are produced, falling-tone chorus <span class="hlt">element</span> generation has yet to be explained. Our new model proposes that weak-amplitude falling-tone chorus <span class="hlt">elements</span> can be generated by magnetospheric reflection of rising-tone <span class="hlt">elements</span>. Using ray tracing in a realistic plasma model of the inner magnetosphere, we demonstrate that rising-tone <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100025482','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100025482"><span>In Situ Instrumentation for Sub-Surface Planetary <span class="hlt">Geochemistry</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bodnarik, J.; Evans, L.; Floyd, S.; Lim, L.; McClanahan, T.; Namkung, M.; Parsons, A.; Schweitzer, J.; Starr, R.; Trombka, J.</p> <p>2010-01-01</p> <p>Novel instrumentation is under development at NASA's Goddard Space Flight Center, building upon <span class="hlt">earth</span>-based techniques for hostile environments, to infer geochemical processes important to formation and evolution of solid bodies in our Solar System. A prototype instrument, the Pulsed Neutron Generator Gamma Ray and Neutron Detectors (PNG-GRAND), has a 14 MeV pulsed neutron generator coupled with gamma ray and neutron detectors to measure quantitative <span class="hlt">elemental</span> concentrations and bulk densities of a number of major, minor and trace <span class="hlt">elements</span> at or below the surfaces with approximately a meter-sized spatial resolution down to depths of about 50 cm without the need to drill. PNG-GRAND's in situ a meter-scale measurements and adaptability to a variety of extreme space environments will complement orbital kilometer-scale and in-situ millimeter scale <span class="hlt">elemental</span> and mineralogical measurements to provide a more complete picture of the <span class="hlt">geochemistry</span> of planets, moons, asteroids and comets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23932372','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23932372"><span>Selective liquid chromatographic separation of yttrium from heavier rare <span class="hlt">earth</span> <span class="hlt">elements</span> using acetic acid as a novel eluent.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kifle, Dejene; Wibetoe, Grethe</p> <p>2013-09-13</p> <p>One of the major difficulties in the rare <span class="hlt">earth</span> <span class="hlt">elements</span> separation is purification of yttrium from heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Thus, an HPLC method using acetic acid as novel eluent was explored for selective separation of yttrium form the heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span>. When acetic acid is used as a mobile phase yttrium eluted with the lighter lanthanides. This is contrary to its relative position amongst heavier lanthanides when eluents commonly used for separation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> were employed. The shift in elution position of yttrium with acetic acid as eluent may reflect a relatively lower stability constant of the yttrium-AcOH complex (in the same order as for the lighter lanthanides) compared to the corresponding AcOH complexes with heavy lanthanides, enabling selective separation of yttrium from the latter. The method was successfully used for selective separation of yttrium in mixed rare <span class="hlt">earth</span> sample containing about 80% of yttrium and about 20% of heavy rare <span class="hlt">earth</span> oxides. Thus, the use of AcOH as eluent is an effective approach for separating and determining the trace amounts of heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> in large amounts of yttrium matrix. Separation was performed on C18 column by running appropriate elution programs. The effluent from the column was monitored with diode array detector at absorbance wavelength of 658nm after post column derivatization with Arsenazo III.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1784d0014R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1784d0014R"><span>Standardless EDXRF application for quantification of thorium (Th), uranium (U) and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in various Malaysian rare <span class="hlt">earth</span> ores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruf, Mohd Izzat Fahmi Mohd; Bahri, Che Nor Aniza Che Zainul; AL-Areqi, Wadeeah M.; Majid, Amran Ab.</p> <p>2016-11-01</p> <p>Our local rare <span class="hlt">earth</span> ores contained substantial amount of Thorium and Uranium which the level exceed permissible limit adopted by Malaysia and many importing nation. X-ray fluorescence technique has been applied for determination of thorium (Th), uranium (U) and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in Malaysian rare <span class="hlt">earth</span> ores as it's recognized as viable tool. XRF has been widely used in detecting <span class="hlt">elemental</span> composition of unknown materials both qualitative and quantitatively because of its wide range of <span class="hlt">element</span> detection alongside the non-destructive analytical technique with great accuracy and precision. Four types of minerals sample which is monazite, xenotime, ilmenite and zircon were collected from `amang' factory located in famous city of mining, Ipoh and analyzed using EDXRF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V23B3129B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V23B3129B"><span>Zircon trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and growth of the Pleistocene to Holocene Mono Craters rhyolite magma system, California (USA)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, N.; Miller, J. S.; Vazquez, J. A.; Marcaida, M.; Lidzbarski, M. I.</p> <p>2015-12-01</p> <p>The Mono Craters, part of the Mono-Inyo volcanic chain in eastern California, comprise at least 27 high-silica Pleistocene to Holocene rhyolite domes, lava flows and tephra cones. The Holocene chronology of the Mono Craters is well constrained but only recently has 238U-230Th zircon and 40Ar/39Ar dating elucidated the Pleistocene eruptive history. We performed trace <span class="hlt">element</span> analysis on dated zircon crystal rims and sectioned interiors (using SHRIMP-RG) from 3 rhyolite domes (21, 12.5, and 7 ka) with additional rim data on 5 ashes separated from juvenile pumice clasts in the correlative Wilson Creek Formation (spanning from 62 to 21 ka). Ti-in-zircon (TTi,zrc) thermometry (titania activity from coexisting Fe-Ti oxides) gives temperatures predominantly between 650°C and 750°C, similar to average zircon saturation temperatures (Tzrc,sat). The observation that Tzrc,sat ≈ TTi,zrc indicates that Mono Craters rhyolite magmas were zircon-saturated and erupted at these temperatures (near water-saturated granite eutectic). Variations in key trace <span class="hlt">elements</span> are relatively limited overall and zircons display similar REE patterns with generally curved MREE to HREE patterns and prominent negative Eu anomalies. Most of the variation is observed in zircons from older eruptions (62-41 ka). Zircon rims from Ash 17 of the Wilson Creek Formation (59 ka) have elevated Th/U, Eu/Eu*, and Ti and lower Hf compared to Ash 19 (62 ka), which suggests a thermal rejuvenation event between these two eruptions. Zircon rims from Ash 15 (41 ka) are characterized by a trend toward high Hf, at relatively low and relatively constant Ti, and low Eu/Eu*, consistent with rhyolite magma undergoing eutectic-like crystallization just prior to eruption. Zircon surfaces and interiors for the 21, 12.5, and 7 ka dome eruptions have very similar Hf, low Eu/Eu*, low Ti, and low Th/U. This requires zircon crystallization in a very uniform thermal and chemical environment from the latest Pleistocene to Holocene</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Litho.264..453T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Litho.264..453T"><span>Trace <span class="hlt">element</span> and isotopic <span class="hlt">geochemistry</span> of Cretaceous magmatism in NE Asia: Spatial zonation, temporal evolution, and tectonic controls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tikhomirov, Petr L.; Kalinina, Elena A.; Moriguti, Takuya; Makishima, Akio; Kobayashi, Katsura; Nakamura, Eizo</p> <p>2016-11-01</p> <p>Results of a comprehensive geochemical study (major and trace <span class="hlt">elements</span>, and isotopes of Sr, Nd, Pb, Hf) of Cretaceous volcanic rocks from the Chukotka area in northeastern Russia are presented. Synthesis of available geological and geochronological data suggests diachronous onset of activity of the Okhotsk-Chukotka volcanic belt (OCVB), the largest magmatic province in the region. The OCVB consists of ca. 106 km3 of volcanic rocks. At 106-105 Ma, subduction-related magmatism initiated in the southern and central segments of the OCVB. In the Central and Northern Chukotka areas, where the northern OCVB is exposed, onset of arc magmatism occurred ca. 10 m.y. after extension-related magmatism of the Chaun igneous province at 109-104 Ma. Mafic rocks from the OCVB yield (87Sr/86Sr)80 Ma of 0.7033 to 0.7047, εNd80 Ma of 0.0 to 7.10, εHf80 Ma of 4.12 to 12.88, (206Pb/204Pb)80 Ma of 18.11 to 18.42, and (208Pb/204Pb)80 Ma of 37.96 to 38.21. Volcanic rocks from the Chaun province, as well as OCVB rocks from Northern Chukotka, originate from a relatively enriched source and have (87Sr/86Sr)80 Ma of 0.7088 to 0.7100, εNd80 Ma of - 5.81 to - 3.42, εHf80 Ma of - 3.40 to - 0.25, (206Pb/204Pb)80 Ma of 18.69 to 18.90, and (208Pb/204Pb)80 Ma of 38.65 to 38.86. No definitive across-arc <span class="hlt">elemental</span> or isotopic zonation of the OCVB has been revealed, probably because of wide-scale crustal melting and subsequent contamination of mantle-derived melts. However, there is a clear along-arc isotopic zonation. In our interpretation, this results from heterogeneity of the subcontinental lithospheric mantle, which likely was a major contributor to the magma source. The similar isotopic signatures of silicic (dominantly crust-derived) and mafic (mantle-derived) volcanic rocks in each OCVB segment imply that remelting of juvenile mafic underplated material was the main process responsible for the crust-derived magma generation. These data from the major Cretaceous magmatic provinces of northeast</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V31A0563M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V31A0563M"><span>Prolonged Eclogite-Facies Metamorphism: Evidence From Geochronology and Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span>, North Qaidam UHP Terrane, NW China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mattinson, C. G.; Wooden, J. L.; Mazdab, F. K.; Liou, J. G.; Bird, D. K.; Wu, C.</p> <p>2006-12-01</p> <p>Amphibolite-facies felsic gneisses near Dulan, at the southeast end of the North Qaidam terrane, enclose minor (<10 vol%) eclogite and peridotite which record ultra-high pressure (UHP) metamorphism. Field relations, and coesite inclusions in zircons from paragneiss suggest that felsic, mafic, and ultramafic rocks all experienced UHP metamorphism and a common amphibolite-facies retrogression. SHRIMP-RG U-Pb and REE analyses of zircons from four eclogites yield weighted mean ages of 449--422 Ma; REE patterns (flat HREE, no Eu anomaly) and inclusions of garnet, omphacite, and rutile indicate that these ages record eclogite-facies metamorphism. Trace <span class="hlt">element</span> variations in zircon are similar to core-to-rim trace <span class="hlt">element</span> zoning of coexisting garnet revealed by LA-ICP-MS analysis. The coherent field relations, and the similar range of individual ages in each sample suggests that the ~25 m.y. age range reflects the duration of eclogite-facies conditions. Ti-in-zircon thermometry results show considerable spread, but may suggest cooling from 650-700°C (442--449 Ma) to 600-650°C (433--422 Ma). One group of zircons yields 770--810°C temperatures, possibly related to granulite-facies overprinting during exhumation. In contrast to Ti-in-zircon, Zr- in-rutile thermometry yields tightly clustered results of 590°C for all four eclogites and one 426 ± 4 Ma paragneiss. The ~25 m.y. duration as well as possible cooling during eclogite-facies metamorphism suggests the UHP rocks decoupled from the downgoing plate, and were refrigerated by continued, structurally deeper subduction. In the Lüliang Shan (350 km NW) in the North Qaidam terrane, eclogite and garnet peridotite ages of 414-- 495 Ma suggest that this locality also records a protracted eclogite-facies history. Evidence of prolonged eclogite-facies metamorphism in other HP/UHP localities (Greenland, Norway, Alps, Dabie-Sulu) suggests that eclogite-facies residence times of >15--25 m.y. may be globally significant in</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhSRv...1...61S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhSRv...1...61S"><span>Use of X-ray Fluorescence Analysis for the Determination of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schramm, Rainer</p> <p>2016-09-01</p> <p>X-ray fluorescence spectrometry (XRF) is a powerful tool for the analysis of solid material. That is the reason why the technique was applied for the determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) since about 1970. At present, energy-dispersive XRF and wavelength-dispersive XRF are used for the analysis of pressed powder pellets or fused Li-borate beads containing REEs. The production of reliable results can only be achieved by careful optimization of the parameter, in particular the selection of spectral lines. The quantification is based on a calibration realized by using reference samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015CryRp..60..921M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CryRp..60..921M"><span>Influence of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (Nd, Sm, Gd) on the physicochemical properties of ges crystal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Madatov, R. S.; Alekperov, A. S.; Magerramova, Dzh. A.</p> <p>2015-11-01</p> <p>Layered semiconductors (including GeS), which are widely used in modern electronics, are of great interest for researchers. New GeS-based devices have been developed for holographic recording, optical processing, and storage of information. In the last few years, American scientists have developed a unique GeS-based device that makes it possible to accumulate an immense amount of solar energy. The introduction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) facilitates the healing of metal and chalcogenide vacancies, removes polytypism, and enhances interlayer interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JOM....65j1276S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JOM....65j1276S"><span>Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span> in Lighting and Optical Applications and Their Recycling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, Xin; Chang, Moon-Hwan; Pecht, Michael</p> <p>2013-10-01</p> <p>Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are used in lighting and optical applications to enable color and light adjustment, miniaturization, and energy efficiency. Common applications of REEs include phosphors for light-emitting diodes, lasers, and electronic video displays. This article reviews how REEs are widely used in these applications. However, supply constraints, including rising prices, environmental concerns over mining and refining processes, and China's control over the supply of the vast majority of REEs, are of concern for manufacturers. In view of these supply constraints, this article discusses ways for manufacturers of lighting and optical devices to identify potential substitutes and recycling methods for REEs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002NIMPB.189..459W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002NIMPB.189..459W"><span>Studies of rare <span class="hlt">earth</span> <span class="hlt">element</span> distribution and action in human erythrocyte and animal hepatocyte by PIXE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Y. P.; Mi, Y.; Shen, H.; Yao, H. Y.; Cheng, Y.; Wang, X.; Zhang, J. X.</p> <p>2002-04-01</p> <p>PIXE analysis is applied to investigate a long-term disputed issue whether the rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) can enter the cell across the cell membrane or not. It has been illustrated that REE could travel across the biomembrane into the cells by cell studies in vitro as well as in studies of animals fed with REEs diet. The binding of REE by membrane changes its permeability and makes intracellular ion transportable. Entrance of REEs may influence the cellular function. In addition, the REE distribution and behavior in cell are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999ESRv...47..219D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999ESRv...47..219D"><span>Medical <span class="hlt">geochemistry</span> of tropical environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dissanayake, C. B.; Chandrajith, Rohana</p> <p>1999-10-01</p> <p>Geochemically, tropical environments are unique. This uniqueness stems from the fact that these terrains are continuously subjected to extreme rainfall and drought with resulting strong geochemical fractionation of <span class="hlt">elements</span>. This characteristic geochemical partitioning results in either severe depletion of <span class="hlt">elements</span> or accumulation to toxic levels. In both these situations, the effect on plant, animal and human health is marked. Medical <span class="hlt">geochemistry</span> involves the study of the relationships between the <span class="hlt">geochemistry</span> of the environment in which we live and the health of the population living in this particular domain. Interestingly, the relationships between <span class="hlt">geochemistry</span> and health are most marked in the tropical countries, which coincidentally are among the poorest in the world. The very heavy dependence on the immediate environment for sustainable living in these lands enables the medical geochemist to observe correlations between particular geochemical provinces and the incidence of certain diseases unique to these terrains. The aetiology of diseases such as dental and skeletal fluorosis, iodine deficiency disorders, diseases of humans and animals caused by mineral imbalances among others, lie clearly in the geochemical environment. The study of the chemistry of the soils, water and stream sediments in relation to the incidence of geographically distributed diseases in the tropics has not only opened up new frontiers in multidisciplinary research, but has offered new challenges to the medical profession to seriously focus attention on the emerging field of medical <span class="hlt">geochemistry</span> with the collaboration of geochemists and epidemiologists.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26782327','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26782327"><span><span class="hlt">Geochemistry</span> of dissolved trace <span class="hlt">elements</span> and heavy metals in the Dan River Drainage (China): distribution, sources, and water quality assessment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meng, Qingpeng; Zhang, Jing; Zhang, Zhaoyu; Wu, Tairan</p> <p>2016-04-01</p> <p>Dissolved trace <span class="hlt">elements</span> and heavy metals in the Dan River drainage basin, which is the drinking water source area of South-to-North Water Transfer Project (China), affect large numbers of people and should therefore be carefully monitored. To investigate the distribution, sources, and quality of river water, this study integrating catchment geology and multivariate statistical techniques was carried out in the Dan River drainage from 99 river water samples collected in 2013. The distribution of trace metal concentrations in the Dan River drainage was similar to that in the Danjiangkou Reservoir, indicating that the reservoir was significantly affected by the Dan River drainage. Moreover, our results suggested that As, Sb, Cd, Mn, and Ni were the major pollutants. We revealed extremely high concentrations of As and Sb in the Laoguan River, Cd in the Qingyou River, Mn, Ni, and Cd in the Yinhua River, As and Sb in the Laojun River, and Sb in the Dan River. According to the water quality index, water in the Dan River drainage was suitable for drinking; however, an exposure risk assessment model suggests that As and Sb in the Laojun and Laoguan rivers could pose a high risk to humans in terms of adverse health and potential non-carcinogenic effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFMGC31B0176L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFMGC31B0176L"><span>Evaluating the Age of Buried Ice in Antarctica Using Ashfall Deposits: New Insights from Deposit Morphology, Grain Shape, and LA-ICP-MS Trace-<span class="hlt">Element</span> <span class="hlt">Geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lewis, A. R.; Marchant, D. R.</p> <p>2003-12-01</p> <p>Dating of buried ice in the western Dry Valleys region relies on 40Ar/39Ar analysis of ashfall deposits within sublimation tills that rest directly on stagnant glacier ice. The oldest ice so dated is >8.1 Ma. The fundamental assumption is that dated ashes are in-situ and have not been transported from surface deposits elsewhere in the Dry Valleys region. Given that the surface of sublimation tills shows well-developed patterned ground, the presumption of ground stability and long-term preservation of in-situ ashfall is questioned. As a test of ground stability, we examined ash-deposit morphology, grain shape, and glass-shard trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> from several ashfall deposits used to provide limiting ages on buried ice and tills in the western Dry Valleys. Detailed field analyses show that ashfall that collects in sublimation tills over buried ice occurs in one of three morphologic settings: surface troughs that delineate sand-wedge polygons, void spaces in gravel-and-cobble lags that overlie active sand wedges, and 1 to 2-cm-wide thermal contraction cracks. Post-depositional sublimation of underlying ice may distort initial deposit morphology through uneven surface lowering. Microscopic analyses of concentrated ashfall deposits that lack detrital sand grains show highly angular glass shards that preserve delicate hair-like spires and thin bubble-wall vesicles. Grain edges are sharp with no chipped, fractured, or pitted surfaces. In contrast, ash deposits containing detrital sand grains show subangular to subrounded shard morphologies with concave fractures and pits on grain edges, all of which are suggestive of abrasion during transport. In such deposits, grains preserving delicate bubble walls and hair-like spires are conspicuously absent. Laser ablation-inductively coupled plasma-mass spectrometry shows that glass shards within each ashfall deposit have uniform trace-<span class="hlt">element</span> geochemical signatures. If ashfall were eroded and transported after initial</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SedG..345...33H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SedG..345...33H"><span>Characteristics of hydrothermal sedimentation process in the Yanchang Formation, south Ordos Basin, China: Evidence from <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>He, Cong; Ji, Liming; Wu, Yuandong; Su, Ao; Zhang, Mingzhen</p> <p>2016-11-01</p> <p>Hydrothermal sedimentation occurred in the Triassic Yanchang Formation, Ordos Basin, China. However, their macroscopic features at the scale of the stratum and hydrothermal sources still lack correlational research. This paper performed <span class="hlt">element</span> geochemical study on a large number of core samples collected from the Yanchang Formation of a new drilling well located in the south Ordos Basin. The SiO2/(K2O + Na2O) vs. MnO/TiO2 crossplot and Fe vs. Mn vs. (Cu + Co + Ni) × 10 ternary diagram demonstrate that the Yanchang stratum in the study area has, in general, hydrothermal components. The Al/(Al + Fe + Mn) and (Fe + Mn)/Ti ratios of the core samples range from 0.34 to 0.84 and 4.81 to 50.54, averaging 0.66 and 10.67, respectively, indicating that the stratum is a set of atypical hydrothermal sedimentation with much terrigenous input. Data analysis shows that the hydrothermal source in the study area was from the deep North Qinling Orogen around the south margin of the basin, where some active tectonic and volcanic activities took place, rather than from the relatively stable internal basin. Early Indosinian movement and volcanic activities activated basement faults around the southern margin of the basin, providing vents for the deep hydrothermal fluid upwelling. The hydrothermal indicators suggest that the study area experienced 4 episodes of relatively stronger hydrothermal activity, namely during the Chang 10, Chang 9-1, Chang 7-3 and Chang 6-2 periods. We also propose a new hydrothermal sedimentation model of hydrothermal fluids overflowing from basin margin faults, for the Yanchang Formation, which is reported here for the first time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21838699','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21838699"><span>Effects of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and REE-binding proteins on physiological responses in plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Dongwu; Wang, Xue; Chen, Zhiwei</p> <p>2012-02-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), which include 17 <span class="hlt">elements</span> in the periodic table, share chemical properties related to a similar external electronic configuration. REEs enriched fertilizers have been used in China since the 1980s. REEs could enter the cell and cell organelles, influence plant growth, and mainly be bound with the biological macromolecules. REE-binding proteins have been found in some plants. In addition, the chlorophyll activities and photosynthetic rate can be regulated by REEs. REEs could promote the protective function of cell membrane and enhance the plant resistance capability to stress produced by environmental factors, and affect the plant physiological mechanism by regulating the Ca²⁺ level in the plant cells. The focus of present review is to describe how REEs and REE-binding proteins participate in the physiological responses in plants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2003/0477/pdf/of03-477.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2003/0477/pdf/of03-477.pdf"><span>A compilation of whole-rock and glass major-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of Kilauea Volcano, Hawai'i, near-vent eruptive products: January 1983 through September 2001</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Thornber, Carl R.; Hon, Ken; Heliker, Christina; Sherrod, David A.</p> <p>2003-01-01</p> <p>This report presents major-<span class="hlt">element</span> geochemical data from 652 glasses (~6,520 analyses) and 795 whole-rock aliquots from 1,002 fresh samples of olivine-tholeiitic lava collected throughout the near-continuous eruption of Kïlauea Volcano, Hawai'i, from January 1983 through September 2001. The data presented herein provide a unique temporal compilation of lava <span class="hlt">geochemistry</span> that best reflects variations of pre-eruptive magma compositions during prolonged rift-zone eruption. This document serves as a repository for geochemical data referred to in U.S. Geological Survey Professional Paper 1676 (Heliker, Swanson, and Takahashi, eds., 2003) which includes multidisciplinary research papers pertaining to the first twenty years of Puu Oo-Kupaianaha eruption activity. Details of eruption characteristics and nomenclature are provided in the introductory chapter of that volume (Heliker and Mattox, 2003). Geochemical relations among all or portions of this data set are depicted and interpreted by Thornber (2003), Thornber and others (2003) and Thornber (2001). Trace <span class="hlt">element</span> compositions and Nd, Sr and Pb isotopic analyses of representative samples of this select eruption suite will be provided in a separate and complimentary open file report. From 1983 to October 2001, approximately 2,500 eruption samples were collected and archived by the U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO). Geochemical data for 1,002 of these samples are included here. Previous reports present bulk-lava major- <span class="hlt">element</span> chemistry for eruption samples collected from 1983 to 1986 and from 1990 to 1994 (Neal and others, 1988 and Mangan and others, 1995, respectively). Major <span class="hlt">element</span> glass chemistry and thermometry data for samples collected from 1983 to 1994 is reported by Helz and Hearn (1998) and whole-rock and glass chemistry for samples collected from September 1994 to October 2001 is provided by Thornber and others (2002). This report is a compilation of previously published data along</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeCoA.200..145F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeCoA.200..145F"><span>Fingerprinting fluid sources in Troodos ophiolite complex orbicular glasses using high spatial resolution isotope and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fonseca, Raúl O. C.; Kirchenbaur, Maria; Ballhaus, Chris; Münker, Carsten; Zirner, Aurelia; Gerdes, Axel; Heuser, Alexander; Botcharnikov, Roman; Lenting, Christoph</p> <p>2017-03-01</p> <p>The Troodos igneous complex (Cyprus) is a ca. 90 Ma old, well preserved supra-subduction zone ophiolite. Troodos is unique in that it shows evidence of fluid-saturation throughout the complex, from its base (i.e. podiform chromitites) to its uppermost units - the upper pillow lavas (UPL). However, it is unclear what the source of dissolved water in UPL tholeiites is, with possibilities including shallow seawater infiltration, assimilation of altered Troodos oceanic crust, recycled serpentinized oceanic crust, or subducted pelagic sediments. In order to identify and characterize these components we have carried out a detailed high-resolution study on tholeiitic lavas on orbicular structures and glasses from the UPL in Troodos. Basaltic orbicules were measured for their Sr-Nd-Hf-Pb isotope compositions, and in situ for their B isotopes using LA-MC-ICP-MS. UPL orbicules display a very narrow range in ɛ Nd and ɛ Hf (+7 to +8 and +13 to +15, respectively) indicating melting of a depleted mantle source. Lead isotopes, specifically 207Pb/204Pb vs. 206Pb/204Pb, form a mixing array with pelagic sediments. Furthermore, high-resolution characterization of individual orbicules revealed that UPL tholeiites display strong variability in 87Sr/86Sr (0.7039-0.7060) at the outcrop scale. Samples display δ11 B between -8.2 (± 0.5)‰ and +5.9 (± 1.1)‰ with an average B content of ca. 5 μg/g. Contrary to expectation, altered orbicules and their associated hyaloclastite matrixes display lower δ11 B (down to -10‰) and higher B contents (max. 200 μg/g) when compared to fresh glass. Furthermore, the orbicules studied here show little or no evidence of interaction with seawater, which is supported by their trace <span class="hlt">element</span> contents and isotope compositions. When all isotope systems are taken into account, UPL lavas reflect melting of a depleted mantle source that was overprinted by hydrous sediment melts, and potentially, fluid-like subduction components that in part originate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993AcSpe..48..507S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993AcSpe..48..507S"><span>Determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in high purity rare <span class="hlt">earth</span> oxides by liquid chromatography, thermionic mass spectrometry and combined liquid chromatography/thermionic mass spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stijfhoorn, D. E.; Stray, H.; Hjelmseth, H.</p> <p>1993-03-01</p> <p>A high-performance liquid Chromatographie (HPLC) method for the determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in rocks has been modified and used for the determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in high purity rare <span class="hlt">earth</span> 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 <span class="hlt">earth</span> 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 <span class="hlt">element</span> was not collected, interference from this <span class="hlt">element</span> 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 <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24657942','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24657942"><span>Rare <span class="hlt">earth</span> <span class="hlt">element</span> components in atmospheric particulates in the Bayan Obo mine region.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Lingqing; Liang, Tao; Zhang, Qian; Li, Kexin</p> <p>2014-05-01</p> <p>The Bayan Obo mine, located in Inner Mongolia, China, is the largest light rare <span class="hlt">earth</span> body ever found in the world. The research for rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 μm (PM10) 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(3), and those for PM10 were 42.8 and 68.9 ng/m(3), in August 2012 and March 2013, respectively. Enrichment factor was calculated for all 14 REEs in the TSP and PM10 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 PM10 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 <span class="hlt">elements</span> (La(N)/Yb(N), La(N)/Sm(N), Gd(N)/Yb(N)).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1329003-uptake-effect-rare-earth-elements-gene-expression-methylosinus-trichosporium-ob3b','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1329003-uptake-effect-rare-earth-elements-gene-expression-methylosinus-trichosporium-ob3b"><span>Uptake and effect of rare <span class="hlt">earth</span> <span class="hlt">elements</span> on gene expression in Methylosinus trichosporium OB3b</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Gu, Wenyu; Farhan Ul Haque, Muhammad; DiSpirito, Alan A.; ...</p> <p>2016-05-12</p> <p>It is well-known that M. trichosporium OB3b has two forms of methane monooxygenase responsible for the initial conversion of methane to methanol, a cytoplasmic (soluble) methane monooxygenase (sMMO) and a membrane-associated (particulate) methane monooxygenase (pMMO) and that copper strongly regulates expression of these alternative forms of MMO. More recently, it has been discovered that M. trichosporium OB3b has multiple types of the methanol dehydrogenase (MeDH), i.e. the Mxa-MeDH and Xox-MeDH, and the expression of these two forms is regulated by the availability of the rare <span class="hlt">earth</span> <span class="hlt">element</span>, cerium. Here we extend these studies and show that lanthanum, praseodymium, neodymium andmore » samarium also regulate expression of alternative forms of MeDH. The effect of these rare <span class="hlt">earth</span> <span class="hlt">elements</span> on MeDH expression, however, was only observed in the absence of copper. Further, a mutant of M. trichosporium OB3b where the Mxa-MeDH was knocked out was able to grow in the presence of lanthanum, praseodymium and neodymium, but was not able to grow in the presence of samarium. In conclusion, collectively these data suggest that multiple levels of gene regulation by metals exist in M. trichosporium OB3b but that copper overrides the effect of other metals by an as yet unknown mechanism.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5357645','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5357645"><span>Atomic hydrogen in. gamma. -irradiated hydroxides of alkaline-<span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Spitsyn, V.I.; Yurik, T.K.; Barsova, L.I.</p> <p>1982-04-01</p> <p>Atomic hydrogen is an important intermediate product formed in the radiolysis of compounds containing X-H bonds. H atoms have been detected in irradiated matrices of H/sub 2/ and inert gases at 4/sup 0/K, in irradiated ice and frozen solutions of acids in irradiated salts and in other systems. Here results are presented from a study of the ESR spectra of H atoms generated in polycrystalline hydroxides of alkaline-<span class="hlt">earth</span> <span class="hlt">elements</span> that have been ..gamma..-irradiated at 77/sup 0/K, after preliminary treatment at various temperatures. For the first time stabilization of atomic hydrogen in ..gamma..-irradiated polycrystalline alkaline-<span class="hlt">earth</span> <span class="hlt">element</span> hydroxides has been detected. Depending on the degree of dehydroxylation, several types of hydrogen atoms may be stabilized in the hydroxides, these hydrogen atoms having different radiospectroscopic parameters. In the magnesium-calcium-strontium-barium hydroxide series, a regular decrease has been found in the hfi constants for H atoms with the cations in the immediate surroundings. A direct proportionality has been found between the parameters ..delta..A/A/sub 0/ and the polarizability of the cation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5798936','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5798936"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soils from selected areas on the Island of Hawaii</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Barnard, W.M.; Halbig, J.B.</p> <p>1985-07-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">element</span> (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 <span class="hlt">earth</span> <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EOSTr..93R.202S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93R.202S"><span>While China's dominance in rare <span class="hlt">earths</span> dips, concerns remain about these and other <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Showstack, Randy</p> <p>2012-05-01</p> <p>China's dominance in the production of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">elements</span> used in a variety of electronic, optical, magnetic, and catalytic applications, and despite their name, they are relatively plentiful in the <span class="hlt">Earth</span>'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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009GeCoA..73.1609B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009GeCoA..73.1609B"><span>Seawater rare-<span class="hlt">earth</span> <span class="hlt">element</span> patterns preserved in apatite of Pennsylvanian conodonts?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bright, Camomilia A.; Cruse, Anna M.; Lyons, Timothy W.; MacLeod, Kenneth G.; Glascock, Michael D.; Ethington, Raymond L.</p> <p>2009-03-01</p> <p>Past workers have used rare-<span class="hlt">earth</span> <span class="hlt">element</span> patterns recorded in biogenic apatite as proxies for original seawater chemistry. To explore the potency of this approach, we analyzed Pennsylvanian conodonts from limestones, gray shales, and black shales of the Fort Scott and Pawnee formations (Desmoinesian) and Swope and Dennis formations (Missourian) in Kansas, Missouri, and Iowa, U.S.A. Analysis of individual platform conodonts from seven taxa using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) revealed a consistent enrichment in the middle rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (MREE). Analogous MREE enrichment has been observed in authigenic apatite and bulk samples of phosphate-rich black shales from the same formations. Importantly, however, phosphate-depleted shales intimately associated with the P-rich intervals are relatively depleted in MREE. These antithetic patterns argue convincingly for secondary migration from the bulk sediment into the phosphate, and the extent of MREE enrichment in the conodonts is correlated positively with the total REE content. MREE enrichment in conodonts does not vary systematically as a function of lithology, stratigraphic level, conodont genus, geographic location, or with independent estimates of paleoredox conditions in the bottom waters. Collectively, these results argue for postmortem (diagenetic) REE uptake resulting in a pronounced (and progressive) MREE enrichment. Any cerium anomalies, if initially present, were masked by diagenetic uptake of REE. Paleoenvironmental interpretations of conodont REE, particularly for samples exhibiting MREE enrichment, should therefore be viewed with caution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11676010','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11676010"><span>Composition, characteristic and activity of rare <span class="hlt">earth</span> <span class="hlt">element</span>-bound polysaccharide from tea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, D; Wang, C; Zhao, G; Wei, Z; Tao, Y; Liang, X</p> <p>2001-09-01</p> <p>The compositions and structural characteristics of rare <span class="hlt">earth</span> <span class="hlt">elements</span>-bound polysaccharides from tea (REE-TPS) were studied with the methods of Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Gas Chromatography (GC) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. The results show that polysaccharide from tea (TPS) was a sort of glycoprotein and coordinated with Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) closely. The sugar fraction was composed of Rha, Ara, Xyl, Fuc, Glc, and Gal. There existed almost all natural amino acids with Glx, Asx, and Hyp as the major parts in the protein fraction. The REEs in REE-TPS were mainly composed of La, Ce, and Nd, especially, more than 75% of them was La. The coordination atom of the first coordination shell of La in REE-TPS was oxygen, the coordination number of which was 6, and the average distance between the atoms was 2.52 A. The second shell was formed from sulfur atoms, the coordination number and the average distance were 3 and 2.91 A, respectively. The bio-experiments show that REE-TPS could decrease the content of blood glucose in mice significantly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11195905','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11195905"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span>--a new generation of growth promoters for pigs?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>He, M L; Rambeck, W A</p> <p>2000-01-01</p> <p>The present study which includes two feeding experiments was performed to investigate a possible performance enhancing effect of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REF) in piglets. This performance enhancing effect has been described in the Chinese literature for a long time, however, it was never tested under "western conditions". In the first feeding experiment 72 piglets at a mean BW of 7.3 kg were allotted to a control and to 4 REE groups at different levels of lanthanum chloride or an REE mixture containing mainly chlorides of lanthanum, cerium and praseodymium. The experimental period lasted 5 weeks. Positive effects of REE were found on body weight gain as well as on feed conversion ratio of the piglets. Compared to the control group, the daily weight gain was improved by 2 to 5% and feed conversion was better by up to 7%. These effects were, however, not significant. In the second feeding experiment, piglets (mean BW 17.3 kg) were fed for 8 weeks with a similar REE mixture. Significant positive effects of REE were found on both body weight gain and on feed conversion ratio by 19% and 10%, respectively. This is the first time that a performance enhancing effect of REE in pigs under western feeding conditions has been shown. Since the use of antibiotics as growth promoters in animal feed has been restricted in the European Union recently, rare <span class="hlt">earth</span> <span class="hlt">elements</span> might be of interest as new, safe and inexpensive alternative performance enhancers.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2584670','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2584670"><span>Toward understanding early <span class="hlt">Earth</span> evolution: Prescription for approach from terrestrial noble gas and light <span class="hlt">element</span> records in lunar soils</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ozima, Minoru; Yin, Qing-Zhu; Podosek, Frank A.; Miura, Yayoi N.</p> <p>2008-01-01</p> <p>Because of the almost total lack of geological record on the <span class="hlt">Earth</span>'s surface before 4 billion years ago, the history of the <span class="hlt">Earth</span> 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 <span class="hlt">elements</span> such as He, N, O, Ne, and Ar would shed a new light on this dark age in the <span class="hlt">Earth</span>'s history and resolve three of the most fundamental questions in <span class="hlt">earth</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JChEd..76..475B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JChEd..76..475B"><span>The History and Use of Our <span class="hlt">Earth</span>'s Chemical <span class="hlt">Elements</span>: A Reference Guide (by Robert E. Krebs)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bracken, Reviewed By Jeffrey D.</p> <p>1999-04-01</p> <p>Greenwood Press: Westport, CT, 1998. 282 pp + 25 pp glossary + 37 pp index. 15.9 x 24.1 cm. ISBN 0-313-30123-9. $39.95. This book is an excellent resource for chemical educators at the high school and college levels. The format of the text is consistent and the writing style is clear and concise, making it ideally suited for student use also. The first three chapters serve to introduce the reader to a brief history of chemistry, early models of the atom, and the development of the periodic table. Names of the contributing scientists are mentioned whenever necessary, but the overall purpose of these introductory chapters is simply to lay a foundation for the subsequent seven chapters. A complete glossary of important scientific terms mentioned in the text should allow beginning students to use this book without feeling overwhelmed. Each entry for the 112 <span class="hlt">elements</span> contains the following information: <span class="hlt">elemental</span> symbol, atomic number, period, common valence, atomic weight, natural state, common isotopes, properties, characteristics, abundance, natural sources, history, common uses and compounds, and safety hazards. This information is well organized, with clear headings and separate sections making the book extremely user-friendly. Readers can easily obtain the information they desire without having to skim the full entry for a chosen <span class="hlt">element</span>. One very nice feature of this book is that the <span class="hlt">elements</span> entries are arranged by their locations in the periodic table. For example, chapter 4 contains the alkali metals and alkaline <span class="hlt">earth</span> metals. This organizational scheme allows one to quickly see the patterns and trends within groups of <span class="hlt">elements</span>. This format is significantly better than arranging the <span class="hlt">elements</span> in alphabetical order, which places the entry for sodium far removed from the entries for lithium and potassium. I would highly recommend this book to high school teachers and college chemistry professors. It is well written and is an excellent source of information for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25283836','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25283836"><span>Recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> from the sulfothermophilic red alga Galdieria sulphuraria using aqueous acid.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Minoda, Ayumi; Sawada, Hitomi; Suzuki, Sonoe; Miyashita, Shin-ichi; Inagaki, Kazumi; Yamamoto, Takaiku; Tsuzuki, Mikio</p> <p>2015-02-01</p> <p>The demand for rare <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> <span class="hlt">elements</span>, 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 <span class="hlt">earth</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008GeCoA..72.3964P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008GeCoA..72.3964P"><span>Speciation of adsorbed yttrium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> on oxide surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piasecki, Wojciech; Sverjensky, Dimitri A.</p> <p>2008-08-01</p> <p>The distribution of yttrium and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (YREE) between natural waters and oxide mineral surfaces depends on adsorption reactions, which in turn depend on the specific way in which YREE are coordinated to mineral surfaces. Recent X-ray studies have established that Y 3+ is adsorbed to the rutile (1 1 0) surface as a distinctive tetranuclear species. However, the hydrolysis state of the adsorbed cation is not known from experiment. Previous surface complexation models of YREE adsorption have suggested two to four cation hydrolysis states coexisting on oxide surfaces. In the present study, we investigate the applicability of the X-ray results to rare <span class="hlt">earth</span> <span class="hlt">elements</span> and to several oxides in addition to rutile using the extended triple-layer surface complexation model. The reaction producing a hydrolyzed tetranuclear surface species 4>SOH+M+2HO=(>SOH)2_M(OH)2++4H was found to account for a significant fraction of the adsorbed Y 3+, La 3+, Nd 3+, Gd 3+, and Yb 3+ on rutile, hematite, alumina and silica over wide ranges of pH and ionic strength. Where adsorption data were available as a function of surface coverage for hematite and silica, an additional reaction involving a mononuclear species could be used to account for the higher surface coverages. However, it is also possible that some of the higher surface coverage data refer to surface precipitation rather than adsorption. The results of the present study provide an internally consistent basis for describing YREE adsorption which could be used to investigate more complex systems in which YREE compete both in aqueous solution and on mineral surfaces with alkaline <span class="hlt">earths</span> and ligands such as carbonate, sulfate, chloride and organic species, in order to build a predictive adsorption model applicable to natural waters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15478941','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15478941"><span>Distribution characteristics of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in children's scalp hair from a rare <span class="hlt">earths</span> mining area in southern China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tong, Shi-Lu; Zhu, Wang-Zhao; Gao, Zhao-Hua; Meng, Yu-Xiu; Peng, Rui-Ling; Lu, Guo-Cheng</p> <p>2004-01-01</p> <p>In order to demonstrate the validity of using scalp hair rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750007645','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750007645"><span><span class="hlt">Earth</span> Observatory Satellite system definition study. Report no. 5: System design and specifications. Part 1: Observatory system <span class="hlt">element</span> specifications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1974-01-01</p> <p>The performance, design, and quality assurance requirements for the <span class="hlt">Earth</span> Observatory Satellite (EOS) Observatory and Ground System program <span class="hlt">elements</span> required to perform the Land Resources Management (LRM) A-type mission are presented. The requirements for the Observatory <span class="hlt">element</span> with the exception of the instruments specifications are contained in the first part.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....5968H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....5968H"><span>The possible role of hydrogen in the substitution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> into zircon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hinton, R.; MacDonald, R.; Macgarvie, D.; Tindle, A.; Harley, S.</p> <p>2003-04-01</p> <p>Ion microprobe measurements have been made of trace <span class="hlt">element</span> concentrations in zircon and surrounding fresh glass of 5 recently erupted rhyolites. In particular analyses have included not only rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE), but many of the <span class="hlt">elements</span> that have been suggested to be incorporated into zircon. Y and the REE <span class="hlt">elements</span> were found to be the dominant trace <span class="hlt">elements</span> in the zircon and these <span class="hlt">elements</span> varied by over an order of magnitude between grains despite a relatively constant REE content in the surrounding glasses. Strong correlations were observed between Y and all other REE except Ce and Eu. As has been previously observed, the REE partitioning coefficients (zircon/glass) increased strongly from La to Lu. The Ce partitioning was significantly higher than the neighbouring REE (as this <span class="hlt">element</span> dominantly substitutes as the 4+ ion). Whereas it has been previously demonstrated that xenotime substitution occurs in zircon it is clear that in some strongly zoned crystals the P content is insufficient to permit complete charge balance. In the zircons analysed here there also appears to be insufficient P to permit charge balance. The P_2O_5 did not exceed 0.15 wt.% yet the total Y and REE oxide concentrations ranged up to about 2 wt.%. Concentrations of other trace <span class="hlt">elements</span> were invariably very low (Li, Na, K, Be, Mg, Ca, Sr and Ba) less than 7 ppm and Al less than 5 ppm wt. Sc, Ti and Fe were less than 40 ppm wt. and V, Cr and Mn less than 1 ppm wt. F concentrations (7 to 200 ppm wt.) correlated poorly with Y and the REE but were about an order of magnitude too low to permit any major charge coupling with the REE. Although no zircon water standard was available, initial estimates of the water content suggest that the zircons contained between 0.01 to 0.09 wt.% H_2O (background approximately 0.008 wt.% H_2O). Somewhat surprisingly the H contents displayed a very good correlation with the Y (and REE) content. Further, although low, these water concentrations appear to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012107','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012107"><span>Composition of the <span class="hlt">earth</span>'s upper mantle-I. Siderophile trace <span class="hlt">elements</span> in ultramafic nodules</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morgan, J.W.; Wandless, G.A.; Petrie, R.K.; Irving, A.J.</p> <p>1981-01-01</p> <p>Seven siderophile <span class="hlt">elements</span> (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 <span class="hlt">elements</span>, 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 <span class="hlt">elements</span> Ni, Co and Ge are very uniform in all rocks, and are much higher than those of the highly siderophile <span class="hlt">elements</span> 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 <span class="hlt">elements</span> in the <span class="hlt">Earth</span>. The moderately siderophile <span class="hlt">elements</span> cannot be derived from the same source as the highly siderophile <span class="hlt">elements</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25278442','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25278442"><span>Effect of the addition of low rare <span class="hlt">earth</span> <span class="hlt">elements</span> (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> are promising alloying <span class="hlt">element</span> candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> <span class="hlt">element</span> concentrations. We showed that low concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> do not promote bone growth inside a 750 μm 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 <span class="hlt">earth</span> <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ESASP.672E..88S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ESASP.672E..88S"><span>On Re-Entry Prediction of Near <span class="hlt">Earth</span> Objects with Genetic Algorithm Using KS <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharma, R. K.; Anilkumar, A. K.; Xavier James Raj, M.; Sabarinath, A.</p> <p>2009-03-01</p> <p>The accurate orbit prediction of the near-<span class="hlt">Earth</span> objects is an important requirement for the re-entry and the life time estimation. The method of Kustaanheimo and Stiefel (KS) total energy <span class="hlt">element</span> equations is one of the powerful methods for orbit prediction. Recently, due to the reentries of large number of risk objects, which posses threat to the human life and property, a great concern is developed in the space scientific community. Consequently, the prediction of risk objects re-entry time and location has got much importance for the proper planning of mitigation strategies and hazard assessment. This paper discusses an integrated procedure for orbit life time prediction combining the KS <span class="hlt">elements</span> and genetic algorithm (GA). The orbit prediction is carried out by numerically integrating the KS <span class="hlt">element</span> equations. In this methodology, the ballistic coefficient is estimated from a set of observed orbital parameters in terms of the Two Line <span class="hlt">Elements</span> (TLE) by minimizing the variance of the predicted re-entry time from different TLE using GA. A software, KSGEN, systematically developed in-house using KS <span class="hlt">elements</span> and genetic algorithm is utilized for predicting the re-entry time of the risk objects. This software has been effectively used for the prediction of the re-entry time in the past seven re-entry exercise campaigns conducted by the Inter Agency Space Debris Coordination Committee (IADC). The predicted re-entry time matched quite well with the actual re-entry time for all the seven IADC re-entry campaigns. A detailed analysis is carried out with two case studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B32D..03Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B32D..03Z"><span>Cracking the Code of Soil Genesis. The Early Role of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaharescu, D. G.; Dontsova, K.; Burghelea, C. I.; Maier, R. M.; Huxman, T. E.; Chorover, J.</p> <p>2014-12-01</p> <p>Soil is terrestrial life support system. Its genesis involves tight interactions between biota and mineral surfaces that mobilize structural <span class="hlt">elements</span> into biogeochemical cycles. Of all chemical <span class="hlt">elements</span> rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are a group of 16 non-nutrient <span class="hlt">elements</span> 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 <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26515437','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26515437"><span>Levels of platinum group <span class="hlt">elements</span> and rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in wild mushroom species growing in Poland.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mleczek, Mirosław; Niedzielski, Przemysław; Kalač, Pavel; Siwulski, Marek; Rzymski, Piotr; Gąsecka, Monika</p> <p>2016-01-01</p> <p>Due to limited data-describing abilities of mushrooms to accumulate platinum group <span class="hlt">elements</span> (PGEs) and rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870038811&hterms=Cerium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DCerium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870038811&hterms=Cerium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DCerium"><span>Siderophile and chalcophile <span class="hlt">element</span> abundances in oceanic basalts, Pb isotope evolution and growth of the <span class="hlt">earth</span>'s core</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Newsom, H. E.; White, W. M.; Jochum, K. P.; Hofmann, A. W.</p> <p>1986-01-01</p> <p>The hypothesis that the mantle Pb isotope ratios reflect continued extraction of Pb into the <span class="hlt">earth</span>'s core over geologic time is evaluated by studying the depeletion of chalcophile and siderophile <span class="hlt">elements</span> in the mantle. Oceanic basalt samples are analyzed in order to determine the Pb, Sr, and Nd isotropic compositions and the abundances of siderophile and chalcophile <span class="hlt">elements</span> and incompatible lithophile <span class="hlt">elements</span>. The data reveal that there is no systematic variation of siderophile or chalcophile <span class="hlt">element</span> abundances relative to abundances of lithophile <span class="hlt">elements</span> and the Pb/Ce ratio of the mantle is constant. It is suggested that the crust formation involves nonmagmatic and magmatic processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026144','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026144"><span>'Nano' Morphology and <span class="hlt">Element</span> Signatures of Early Life on <span class="hlt">Earth</span>: A New Tool for Assessing Biogenicity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oehler, D. Z.; Mostefaoui, S.; Meibom, A.; Selo, M.; McKay, D. S.; Robert, F.</p> <p>2006-01-01</p> <p>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 <span class="hlt">element</span> and isotope analysis at sub-micron resolution. In 2005, Robert et al. [1] combined NanoSIMS <span class="hlt">element</span> 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 <span class="hlt">elements</span> with a 50 nm spatial resolution provides new biologic markers that could help define the timing of life s development on <span class="hlt">Earth</span>. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21173982','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21173982"><span>Accumulation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in human bone within the lifespan.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zaichick, Sofia; Zaichick, Vladimir; Karandashev, Vasilii; Nosenko, Sergey</p> <p>2011-02-01</p> <p>For the first time, the contents of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in a rib bone of a healthy human were determined. The mean value of the contents of Ce, Dy, Er, Gd, La, Nd, Pr, Sm, Tb, and Yb (10 <span class="hlt">elements</span> out of 17 total REEs), as well as the upper limit of means for Ho, Lu, Tm, and Y (4 <span class="hlt">elements</span>) were measured in the rib bone tissue of 38 females and 42 males (15 to 55 years old) using inductively coupled plasma mass spectrometry (ICP-MS). We found age-related accumulation of REEs in the bone tissue of healthy individuals who lived in a non-industrial region. It was calculated that during a lifespan the content of REEs in a skeleton of non-industrial region residents may increase by one to two orders of magnitude. Using our results as indicative normal values and published data we estimated relative Gd accumulation in the bone tissue of patients according to magnetic resonance imaging with contrast agent and La accumulation in the bone tissue of patients receiving hemodialysis after treatment with lanthanum carbonate as a phosphate binder. It was shown that after such procedures contents of Gd and La in the bone tissue of patients are two to three orders of magnitude higher than normal levels. In our opinion, REEs incorporation may affect bone quality and health similar to other potentially toxic trace metals. The impact of elevated REEs content on bone physiology, biochemistry and morphology requires further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JVGR..287....1F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JVGR..287....1F"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in sinters from the geothermal waters (hot springs) on the Tibetan Plateau, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, Jin-Liang; Zhao, Zhen-Hong; Chen, Feng; Hu, Hai-Ping</p> <p>2014-10-01</p> <p>The mineralogical and geochemical composition of sinters from the geothermal areas on the Tibetan Plateau was determined. They occur as siliceous, salty and calcareous sinters but biogenic siliceous sinters were also found. The analyses indicate that there are no distinct inter -<span class="hlt">element</span> relationships between individual rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and other <span class="hlt">elements</span>. Formed from the same geothermal water, the mineralogical and chemical composition of the sinters is influenced by their genesis and formation conditions. The REE distributions depend on the origin of the sinters. Fe-Mn phases in sinters tend to scavenge more REEs from geothermal water. Neither the REE fractionation nor the Ce anomaly seems to be associated with Fe-Mn phases in the sinters. The fourth tetrads of some sinters display weak W-type (concave) effects. In contrast, the third tetrads present large effects in some sinters due to positive Gd anomalies. The origin of the positive Eu anomalies in some sinters seems to be caused by preferential dissolution of feldspars during water-rock interaction. The complexing ligands in geothermal water may contribute significantly to the fractionation of REEs in sinters. The dominant CO32- and HCO3- complexing in geothermal water favors enrichment of heavy REEs in calcareous sinters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15202236','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15202236"><span>[Speciation and distribution characters of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Baotou Section of the Yellow River].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>He, Jiang; Mi, Na; Kuang, Yun-chen; Fan, Qing-yun; Wang, Xia; Guan, Wei; Li, Gui-hai; Li, Chao-sheng; Wang, Xi-wei</p> <p>2004-03-01</p> <p>As a whole of water column, suspended matter and surface sediment in the mainstream and the branch taking up industry wastewater, speciation and distribution characters of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) were investigated systemically in the Baotou section of the Yellow River. This study shows that rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the mainstream of the Baotou section of the Yellow River mainly exist in suspended particles, and the dissolved contents are in extremely minute quantities. REEs mainly exist in dissolved particles in the branch taking up industry wastewater, and suspended sigma REE and dissolved sigma REE are obviously higher than those in the mainstream. The change of sigma REE of dissolved particles in water phase along the Baotou section of the Yellow River is very similar to that of sigma REE of suspended particles, and consistent along the main river, it is that sigma REE increase appreciably from the control profile to the keystone discharged section, come to a head in the D site and reduce in the E site. This distribution pattern indicates pile industry wastewater of Baotou to rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the mainstream of the Yellow River, particularly LREE. The REE distribution in the mainstream of the Baotou section of the Yellow River is the same, with LREE enrichment and Eu depletion. But LREE origin of D site is different from the other sites by excursion of LREE distribution curve and other geochemical parameters, they are origin of industry wastewater piled, otherwise the other four sites are origin of loess altiplano. And HREE are origin of loess altiplano in all the sites. The speciation characteristics of REE in the sediments and suspended matter are quite similar with the amount in as follows: residual > bound to carbonates, bound to Fe-Mn oxides > bound to organic matter > exchangeable. REEs exchangeable in surface sediment and suspended matter in the branch taking up industry wastewater are higher than those in the mainstream, it confirms that REEs in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860050790&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DPeridotite','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860050790&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DPeridotite"><span>Transition region of the <span class="hlt">earth</span>'s upper mantle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, D. L.; Bass, J. D.</p> <p>1986-01-01</p> <p>The chemistry of the <span class="hlt">earth</span>'s mantle is discussed using data from cosmochemistry, <span class="hlt">geochemistry</span>, petrology, seismology, and mineral physics. The chondritic <span class="hlt">earth</span>, the upper mantle and the 400-km discontinuity, the transition region, lower mantle mineralogy, and surface wave tomography are examined. Three main issues are addressed: (1) whether the mantle is homogeneous in composition or chemically stratified, (2) whether the major <span class="hlt">element</span> chemistry of the mantle is more similar to upper mantle peridotites or to chondrites, and (3) the nature of the composition of the source region of basalts erupted at midocean ridges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AtmEn..44.2563M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AtmEn..44.2563M"><span>Physicochemical variations in atmospheric aerosols recorded at sea onboard the Atlantic-Mediterranean 2008 Scholar Ship cruise (Part II): Natural versus anthropogenic influences revealed by PM 10 trace <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moreno, Teresa; Pérez, Noemi; Querol, Xavier; Amato, Fulvio; Alastuey, Andrés; Bhatia, Ravinder; Spiro, Baruch; Hanvey, Melanie; Gibbons, Wes</p> <p>2010-07-01</p> <p>The <span class="hlt">geochemistry</span> of PM 10 filter samples collected at sea during the Scholar Ship Atlantic-Mediterranean 2008 research cruise reveals a constantly changing compositional mix of pollutants into the marine atmosphere. Source apportionment modelling using Positive Matrix Factorization identifies North African desert dust, sea spray, secondary inorganic aerosols, metalliferous carbon, and V-Ni-bearing combustion particles as the main PM 10 factors/sources. The least contaminated samples show an upper continental crust composition (UCC)-normalised <span class="hlt">geochemistry</span> influenced by seawater chemistry, with marked depletions in Rb, Th and the lighter lanthanoid <span class="hlt">elements</span>, whereas the arrival of desert dust intrusions imposes a more upper crustal signature enriched in "geological" <span class="hlt">elements</span> such as Si, Al, Ti, Rb, Li and Sc. Superimposed on these natural background aerosol loadings are anthropogenic metal aerosols (e.g. Cu, Zn, Pb, V, and Mn) which allow identification of pollution sources such as fossil fuel combustion, biomass burning, metalliferous industries, and urban-industrial ports. A particularly sensitive tracer is La/Ce, which rises in response to contamination from coastal FCC oil refineries. The Scholar Ship database allows us to recognise seaborne pollution sourced from NW Africa, the Cape Verde and Canary islands, and European cities and industrial complexes, plumes which in extreme cases can produce a downwind deterioration in marine air quality comparable to that seen in many cities, and can persist hundreds of kilometres from land.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/unnumbered/70039454/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/unnumbered/70039454/report.pdf"><span><span class="hlt">Earth</span> Science Information System (ESIS)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>,</p> <p>1982-01-01</p> <p>The <span class="hlt">Earth</span> Science Information System (ESIS) was developed in 1981 by the U.S. Geological Survey's Office of the Data Administrator. ESIS serves as a comprehensive data management facility designed to support the coordination, integration, and standardization of scientific, technical, and bibliographic data of the U.S. Geological Survey (USGS). ESIS provides, through an online interactive computer system, referral to information about USGS data bases, data <span class="hlt">elements</span> which are fields in the records of data bases, and systems. The data bases contain information about many subjects from several scientific disciplines such as: geology, geophysics, <span class="hlt">geochemistry</span>, hydrology, cartography, oceanography, geography, minerals exploration and conservation, and satellite data sensing.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MMTB...48..956L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MMTB...48..956L"><span>Liquid Inclusions in Heat-Resistant Steel Containing Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Yandong; Liu, Chengjun; Zhang, Tongsheng; Jiang, Maofa; Peng, Cheng</p> <p>2017-04-01</p> <p>Abundant thermodynamic data of pure substances were incorporated in the coupled thermodynamic model of inclusion precipitation and solute micro-segregation during the solidification of heat-resistant steel containing rare <span class="hlt">earth</span> <span class="hlt">elements</span>. The liquid inclusions Ce2 x Al2 y Si1- x-y O z (0 < x < 1, 0 < y < x and z = 1 - x - y) were first introduced to ensure the model more accurately. And the computational method for generation Gibbs free energy of liquid inclusions in molten steel was given. The accuracy of accomplished model was validated through plant trials, lab-scale experiments, and the data published in the literature. The comparisons of results calculated by FactSage with the model were also discussed. Finally, the stable area of liquid inclusions was predicted and the liquid inclusions with larger size were found in the preliminary experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22492828','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22492828"><span>Binary rare <span class="hlt">earth</span> <span class="hlt">element</span>-Ni/Co metallic glasses with distinct β-relaxation behaviors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhu, Z. G.; Wang, Z.; Wang, W. H.</p> <p>2015-10-21</p> <p>We report the formation of a series of rare <span class="hlt">earth</span> <span class="hlt">element</span> (RE)-Ni/Co binary metallic glasses (MGs) with unusual distinct β-relaxation peak compared with that of most of the reported MGs which usually exhibit as an excess wing or a shoulder. The β-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 β-relaxation can serve as model system to investigate the nature of the β-relaxation as well as its relations with other physical and mechanical properties of MGs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730043515&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2527%2527rare%2Bearths%2527%2527','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730043515&hterms=rare+earths&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2527%2527rare%2Bearths%2527%2527"><span>Rare <span class="hlt">earths</span>, other trace <span class="hlt">elements</span> and iron in Luna 20 samples.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Helmke, P. A.; Blanchard, D. P.; Jacobs, J. W.; Haskin, L.; Haskin, A.</p> <p>1973-01-01</p> <p>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-<span class="hlt">earth</span> <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22257887','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22257887"><span>Study on the electrochemical extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> from FLINAK</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Long, Dewu; Huang, Wei; Jiang, Feng; Tian, Lifang; Li, Qingnuan</p> <p>2013-07-01</p> <p>Electrochemical behaviors of rare <span class="hlt">earth</span> <span class="hlt">elements</span>, 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)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AIPC.1702s0004G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPC.1702s0004G"><span>Predictive model for ionic liquid extraction solvents for rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grabda, Mariusz; Oleszek, Sylwia; Panigrahi, Mrutyunjay; Kozak, Dmytro; Eckert, Franck; Shibata, Etsuro; Nakamura, Takashi</p> <p>2015-12-01</p> <p>The purpose of our study was to select the most effective ionic liquid extraction solvents for dysprosium (III) fluoride using a theoretical approach. Conductor-like Screening Model for Real Solvents (COSMO-RS), based on quantum chemistry and the statistical thermodynamics of predefined DyF3-ionic liquid systems, was applied to reach the target. Chemical potentials of the salt were predicted in 4,400 different ionic liquids. On the base of these predictions set of ionic liquids' ions, manifesting significant decrease of the chemical potentials, were selected. Considering the calculated physicochemical properties (hydrophobicity, viscosity) of the ionic liquids containing these specific ions, the most effective extraction solvents for liquid-liquid extraction of DyF3 were proposed. The obtained results indicate that the COSMO-RS approach can be applied to quickly screen the affinity of any rare <span class="hlt">earth</span> <span class="hlt">element</span> for a large number of ionic liquid systems, before extensive experimental tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AcGeo..61..876S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AcGeo..61..876S"><span>Naturally occurring radionuclides and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in weathered Japanese soil samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sahoo, Sarata; Hosoda, Masahiro; Prasad, Ganesh; Takahashi, Hiroyuki; Sorimachi, Atsuyuki; Ishikawa, Tetsuo; Tokonami, Shinji; Uchida, Shigeo</p> <p>2013-08-01</p> <p>The activity concentrations of 226Ra and 228Ac in weathered Japanese soils from two selected prefectures have been measured using a γ-ray spectroscopy system with high purity germanium detector. The uranium, thorium, and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) concentrations were determined from the same soil samples using inductively coupled plasma mass spectrometry (ICP-MS). For example, granitic rocks contain higher amounts of U, Th, and light REEs compared to other igneous rocks such as basalt and andesites. Therefore, it is necessary to understand the interaction between REEs and nature of soils since soils are complex heterogeneous mixture of organic and inorganic solids, water, and gases. In this paper, we will discuss about distribution pattern of 238U and 232Th along with REEs in soil samples of weathered acid rock (granite) collected from two prefectures of Japan: Hiroshima and Miyagi.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6868110','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6868110"><span>Lagrangian finite <span class="hlt">element</span> analysis of the penetration of <span class="hlt">earth</span> penetrating weapons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rosinsky, R.W.</p> <p>1985-11-22</p> <p>Buried targets, such as hardened missile silos, that are resistant to the effects of air blast from above-ground or surface-burst explosions may be vulnerable to the effects of ground motion produced by nearby underground explosions. An <span class="hlt">earth</span> penetrating weapon (EPW) is being developed to exploit this phenomena. To design the EPW system, loads on the weapon due to the penetration event must be determined. This paper presents the methodology for performing Lagrangian finite-<span class="hlt">element</span> analysis of the penetration event in two and three dimensions. In order to describe the methodology, results from analyses done for a particular EPW impacting a particular target medium are presented. The results for impacts with nonzero angles of incidence and nonzero angles of attack show the importance of being able to calculate three dimensional penetration loads. 62 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/792697','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/792697"><span>Behavior of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> In Geothermal Systems; A New Exploration/Exploitation Tool</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scott A. Wood</p> <p>2002-01-28</p> <p>The goal of this four-year project was to provide a database by which to judge the utility of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750027184&hterms=ionic+liquids&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dionic%2Bliquids','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750027184&hterms=ionic+liquids&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dionic%2Bliquids"><span>The distribution of Sr and REE between diopside and silicate liquid. [Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grutzeck, M.; Kridelbaugh, S.; Weill, D.</p> <p>1974-01-01</p> <p>Experimental determination of the distribution coefficients in diopside-liquid pairs for strontium and nine rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in the system CaMgSi2O6-NaAlSi3O8-CaAl2Si2O8. In experiments in air at 1265 C it is found that most of the Sr(2+), Eu(2+), and RE(3+) ions substitute for Ca(2+) and, in addition, a coupled substitution of Al(3+) for Si(4+) occurs. All of the trace ions considered are found to be excluded from the diopside lattice relative to the liquid. In the case of the trivalent ions the exclusion is much more pronounced for La and Ce, which have ionic radii larger than that of Ca(2+) in 8-fold oxygen coordination. Divalent Sr and Eu with even larger radii are also strongly excluded.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9258470','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9258470"><span>Bioelectrical activity of the central nervous system among populations in a rare <span class="hlt">earth</span> <span class="hlt">element</span> area.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhu, W; Xu, S; Shao, P; Zhang, H; Wu, D; Yang, W; Feng, J</p> <p>1997-04-01</p> <p>Auditory brainstem electric response (ABR) and somatosensory evoked potential (SEP) of 21 subjects (41 ears) among villagers in a rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) area in Gan County, Jiangxi, China, were studied. No difference in ABR between the subjects from the REE area and the control group was noted. However, the conduction detected by SEP from the median nerve to the thalamus (P15) was shortened (P < 0.05), especially to the first-grade primary somatosensory responsive region (S1) (P < 0.01) and the amplitude of S1 decreased (P < 0.05), indicating that REE was difficult to accumulate in the brainstem, but it was susceptible to cerebral cortex, thus causing sub-clinical damage. This condition was confirmed in the animal experiment. It was suggested that the toxicity through long-term intake of small doses of REE might not be negligible, and the hazard of REE environments should be investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22499193','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22499193"><span>Predictive model for ionic liquid extraction solvents for rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Grabda, Mariusz; Oleszek, Sylwia; Panigrahi, Mrutyunjay; Kozak, Dmytro; Shibata, Etsuro; Nakamura, Takashi; Eckert, Franck</p> <p>2015-12-31</p> <p>The purpose of our study was to select the most effective ionic liquid extraction solvents for dysprosium (III) fluoride using a theoretical approach. Conductor-like Screening Model for Real Solvents (COSMO-RS), based on quantum chemistry and the statistical thermodynamics of predefined DyF{sub 3}-ionic liquid systems, was applied to reach the target. Chemical potentials of the salt were predicted in 4,400 different ionic liquids. On the base of these predictions set of ionic liquids’ ions, manifesting significant decrease of the chemical potentials, were selected. Considering the calculated physicochemical properties (hydrophobicity, viscosity) of the ionic liquids containing these specific ions, the most effective extraction solvents for liquid-liquid extraction of DyF{sub 3} were proposed. The obtained results indicate that the COSMO-RS approach can be applied to quickly screen the affinity of any rare <span class="hlt">earth</span> <span class="hlt">element</span> for a large number of ionic liquid systems, before extensive experimental tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16038502','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16038502"><span>X-ray fluorescence analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in rocks using low dilution glass beads.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakayama, Kenichi; Nakamura, Toshihiro</p> <p>2005-07-01</p> <p>Major and trace <span class="hlt">elements</span> (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 <span class="hlt">earth</span> <span class="hlt">elements</span>. 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 <span class="hlt">elements</span> 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 <span class="hlt">elements</span> in four rhyolitic and granitic rocks from Japan.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018161','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018161"><span>Record of middle Pleistocene climate change from Buck Lake, Cascade Range, southern Oregon - Evidence from sediment magnetism, trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span>, and pollen</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rosenbaum, J.G.; Reynolds, R.L.; Adam, D.P.; Drexler, J.; Sarna-Wojcicki, A. M.; Whitney, G.C.</p> <p>1996-01-01</p> <p>Comparison of systematic variations in sediment magnetic properties to changes in pollen assemblages in middle Pleistocene lake sediments from Buck Lake indicates that the magnetic properties are sensitive to changes in climate. Buck Lake is located in southern Oregon just east of the crest of the Cascade Range. Lacustrine sediments, from 5.2 to 19.4 m in depth in core, contain tephra layers with ages of ???300-400 ka at 9.5 m and ???400-470 ka at 19.9 m. In these sediments magnetic properties reflect the absolute amount and relative abundances of detrital Fe-oxide minerals, titanomagnetite and hematite. The lacustrine section is divided into four zones on the basis of magnetic properties. Two zones (19.4-17.4 m and 14.5-10.3 m) of high magnetic susceptibility contain abundant Fe oxides and correspond closely to pollen zones that are indicative of cold, dry environments. Two low-susceptibility zones (17.4-14.5 m and 10.3-5.3 m) contain lesser amounts of Fe oxides and largely coincide with zones of warm-climate pollen. Transitions from cold to warm climate based on pollen are preceded by sharp changes in magnetic properties. This relation suggests that land-surface processes responded to these climate changes more rapidly than did changes in vegetation as indicated by pollen frequencies. Magnetic properties have been affected by three factors: (1) dissolution of Fe oxides, (2) variation in heavy-mineral content, and (3) variation in abundance of fresh volcanic rock fragments. Trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span>, employing Fe and the immobile <span class="hlt">elements</span> Ti and Zr, is utilized to detect postdepositional dissolution of magnetic minerals that has affected the magnitude of magnetic properties with little effect on the pattern of magnetic-property variation. Comparison of Ti and Zr values, proxies for heavy-mineral content, to magnetic properties demonstrates that part of the variation in the amount of magnetite and nearly all of the variation in the amount of hematite are due to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GGG.....8.6014T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GGG.....8.6014T"><span>Constraints on Hadean zircon protoliths from oxygen isotopes, Ti-thermometry, and rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trail, Dustin; Mojzsis, Stephen J.; Harrison, T. Mark; Schmitt, Axel K.; Watson, E. Bruce; Young, Edward D.</p> <p>2007-06-01</p> <p>We report zircon oxygen isotope ratios and reconnaissance Ti-in-zircon concentrations, guided by cathodoluminescence image studies, for detrital zircons up to 4.34 Ga from the Narryer Gneiss Complex of Western Australia. Zircon oxygen isotope results bolster the view that some Hadean (>3.85 Ga) zircon source melts were enriched in heavy oxygen, a sensitive proxy for melt contamination by sediments altered in liquid water. Zircon crystallization temperatures calculated from Ti concentration in pre-3.8 Ga zircons yield values around 680°C in all cases except for one lower value in a 4.0 Ga grain. Elevated zircon δ18O values reported here and elsewhere, combined with low minimum-melt crystallization temperatures, and analysis of zircon/melt partitioning of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) provide mutually consistent lines of evidence that the Hadean <span class="hlt">Earth</span> supported an evolved rock cycle which included formation of granitic water-saturated melts, extensive continental crust, hydrosphere-lithosphere interactions, and sediment recycling within the first 150 million years of planet formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMPP31C2047C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMPP31C2047C"><span>Planktonic foraminiferal rare <span class="hlt">earth</span> <span class="hlt">elements</span> as a potential new aeolian dust proxy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chou, C.; Liu, Y.; Lo, L.; Wei, K.; Shen, C.</p> <p>2012-12-01</p> <p>Characteristics of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have widely been used as important tracers in many fields of <span class="hlt">earth</span> 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 μm) 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 δ18O 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26836847','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26836847"><span>Bioadsorption of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> through Cell Surface Display of Lanthanide Binding Tags.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Dan M; Reed, David W; Yung, Mimi C; Eslamimanesh, Ali; Lencka, Malgorzata M; Anderko, Andrzej; Fujita, Yoshiko; Riman, Richard E; Navrotsky, Alexandra; Jiao, Yongqin</p> <p>2016-03-01</p> <p>With the increasing demand for rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in many emerging clean energy technologies, there is an urgent need for the development of new approaches for efficient REE extraction and recovery. As a step toward this goal, we genetically engineered the aerobic bacterium Caulobacter crescentus for REE adsorption through high-density cell surface display of lanthanide binding tags (LBTs) on its S-layer. The LBT-displayed strains exhibited enhanced adsorption of REEs compared to cells lacking LBT, high specificity for REEs, and an adsorption preference for REEs with small atomic radii. Adsorbed Tb(3+) could be effectively recovered using citrate, consistent with thermodynamic speciation calculations that predicted strong complexation of Tb(3+) by citrate. No reduction in Tb(3+) adsorption capacity was observed following citrate elution, enabling consecutive adsorption/desorption cycles. The LBT-displayed strain was effective for extracting REEs from the acid leachate of core samples collected at a prospective rare <span class="hlt">earth</span> mine. Our collective results demonstrate a rapid, efficient, and reversible process for REE adsorption with potential industrial application for REE enrichment and separation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23830573','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23830573"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in human hair from a mining area of China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wei, Binggan; Li, Yonghua; Li, Hairong; Yu, Jiangping; Ye, Bixiong; Liang, Tao</p> <p>2013-10-01</p> <p>Rare <span class="hlt">earth</span> minerals have been mined for more than 50 years in Inner Mongolia of China. In the mining area rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) may be significantly accumulated in humans. Therefore, the aim of this paper is to characterize the REE concentrations in hair of local residents. REE concentrations in hair of 118 subjects were determined. The results showed that the mean concentrations of the determined REE in the hair of both females and males were usually higher from mining area than from control area. The mean concentrations of all the fifteen REE were much higher in hair of males than in hair of females from mining area. This suggested that males might be more sensitive to REE than females. In addition, the mean contents of the REE in hair of miners, particularly light REE (La, Ce, Pr and Nd), were usually much higher than the values in hair of non-miners from both mining area and control area, indicating that the miners were exposed to higher concentrations of REE in occupational environment. Among age groups, the relationships between REE concentrations and age groups showed that more and more concentrations of light REE accumulated in body of both females and males with age until 60 years, while heavy REE concentrations decreased with age in males who were exposed to low concentrations of heavy REE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27816296','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27816296"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> and hypertension risk among housewives: A pilot study in Shanxi Province, China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Bin; Yan, Lailai; Huo, Wenhua; Lu, Qun; Cheng, Zixi; Zhang, Jingxu; Li, Zhiwen</p> <p>2017-01-01</p> <p>Studies have shown that residents living near rare <span class="hlt">earth</span> mining areas have high concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in their hair. However, the adverse effects of REEs on human health have rarely been the focus of epidemiological studies. The goal of this study was to evaluate the relationship between REEs in hair and the risk of hypertension in housewives. We recruited 398 housewives in Shanxi Province, China, consisting of 163 women with hypertension (cases) and 235 healthy women without hypertension (controls). We analyzed 15 REEs (lanthanum (La), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), Yttrium (Y), cerium (Ce), praseodymium (Pr), and neodymium (Nd)) and calcium (Ca) accumulated in housewives hair over a period of two years. The results revealed that, with the exception of Eu, concentrations of the REEs in hair were higher in the cases than in the controls. The univariate odds ratios (ORs) of the 14 REEs were >1, and four of the REEs (Dy, Tm, Yb, and Y) also had adjusted ORs > 1. The increasing dose-response trends of the four REEs further indicated the potential for increased hypertension risk. Moreover, the REEs were negatively correlated with Ca content in hair. These results might suggest an antagonistic effect of REEs on Ca in the human body. It was concluded that high intake of REEs might increase the risk of hypertension among housewives.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1251424','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1251424"><span>Bioadsorption of rare <span class="hlt">earth</span> <span class="hlt">elements</span> through cell surface display of lanthanide binding tags</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Park, Dan M.; Reed, David W.; Yung, Mimi C.; Eslamimanesh, Ali; Lencka, Malgorzata M.; Anderko, Andrzej; Fujita, Yoshiko; Riman, Richard E.; Navrotsky, Alexandra; Jiao, Yongqin</p> <p>2016-02-02</p> <p>In this study, with the increasing demand for rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in many emerging clean energy technologies, there is an urgent need for the development of new approaches for efficient REE extraction and recovery. As a step toward this goal, we genetically engineered the aerobic bacterium <i>Caulobacter crescentus</i> for REE adsorption through high-density cell surface display of lanthanide binding tags (LBTs) on its S-layer. The LBT-displayed strains exhibited enhanced adsorption of REEs compared to cells lacking LBT, high specificity for REEs, and an adsorption preference for REEs with small atomic radii. Adsorbed Tb<sup>3+</sup> could be effectively recovered using citrate, consistent with thermodynamic speciation calculations that predicted strong complexation of Tb<sup>3+</sup> by citrate. No reduction in Tb<sup>3+</sup> adsorption capacity was observed following citrate elution, enabling consecutive adsorption/desorption cycles. The LBT-displayed strain was effective for extracting REEs from the acid leachate of core samples collected at a prospective rare <span class="hlt">earth</span> mine. Our collective results demonstrate a rapid, efficient, and reversible process for REE adsorption with potential industrial application for REE enrichment and separation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1251424-bioadsorption-rare-earth-elements-through-cell-surface-display-lanthanide-binding-tags','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1251424-bioadsorption-rare-earth-elements-through-cell-surface-display-lanthanide-binding-tags"><span>Bioadsorption of rare <span class="hlt">earth</span> <span class="hlt">elements</span> through cell surface display of lanthanide binding tags</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Park, Dan M.; Reed, David W.; Yung, Mimi C.; ...</p> <p>2016-02-02</p> <p>In this study, with the increasing demand for rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in many emerging clean energy technologies, there is an urgent need for the development of new approaches for efficient REE extraction and recovery. As a step toward this goal, we genetically engineered the aerobic bacterium Caulobacter crescentus for REE adsorption through high-density cell surface display of lanthanide binding tags (LBTs) on its S-layer. The LBT-displayed strains exhibited enhanced adsorption of REEs compared to cells lacking LBT, high specificity for REEs, and an adsorption preference for REEs with small atomic radii. Adsorbed Tb3+ could be effectively recovered using citrate,more » consistent with thermodynamic speciation calculations that predicted strong complexation of Tb3+ by citrate. No reduction in Tb3+ adsorption capacity was observed following citrate elution, enabling consecutive adsorption/desorption cycles. The LBT-displayed strain was effective for extracting REEs from the acid leachate of core samples collected at a prospective rare <span class="hlt">earth</span> mine. Our collective results demonstrate a rapid, efficient, and reversible process for REE adsorption with potential industrial application for REE enrichment and separation.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GGG....18..769W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GGG....18..769W"><span>TerraFERMA: The Transparent Finite <span class="hlt">Element</span> Rapid Model Assembler for multiphysics problems in <span class="hlt">Earth</span> sciences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilson, Cian R.; Spiegelman, Marc; van Keken, Peter E.</p> <p>2017-02-01</p> <p>We introduce and describe a new software infrastructure TerraFERMA, the Transparent Finite <span class="hlt">Element</span> Rapid Model Assembler, for the rapid and reproducible description and solution of coupled multiphysics problems. The design of TerraFERMA is driven by two computational needs in <span class="hlt">Earth</span> 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 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 <span class="hlt">Earth</span> 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 multiphysics problems (PETSc), and an options handling system (SPuD) that allows the hierarchical management of all model options. TerraFERMA integrates these libraries into an 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, while still permitting the individual researcher considerable latitude in model construction. TerraFERMA solves partial differential equations using the finite <span class="hlt">element</span> method. It is particularly well suited for nonlinear problems with complex coupling between components. TerraFERMA is open-source and available at http://terraferma.github.io, which includes links to documentation and example input files.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70044201','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70044201"><span>A major light rare-<span class="hlt">earth</span> <span class="hlt">element</span> (LREE) resource in the Khanneshin carbonatite complex, southern Afghanistan</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Tucker, Robert D.; Belkin, Harvey E.; Schulz, Klaus J.; Peters, Stephen G.; Horton, Forrest; Buttleman, Kim; Scott, Emily R.</p> <p>2012-01-01</p> <p>The rapid rise in world demand for the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) has expanded the search for new REE resources. We document two types of light rare-<span class="hlt">earth</span> <span class="hlt">element</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MinDe..49..889S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MinDe..49..889S"><span>Geology and market-dependent significance of rare <span class="hlt">earth</span> <span class="hlt">element</span> resources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simandl, G. J.</p> <p>2014-12-01</p> <p>China started to produce rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare <span class="hlt">earth</span> <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21324705','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21324705"><span>Natural radioactivity and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in feldspar samples, Central Eastern desert, Egypt.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Walley El-Dine, Nadia; El-Shershaby, Amal; Afifi, Sofia; Sroor, Amany; Samir, Eman</p> <p>2011-05-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> <span class="hlt">elements</span> in this area are very high and can be used in different important industries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27289371','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27289371"><span>Evaluation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in groundwater of Lagos and Ogun States, Southwest Nigeria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ayedun, H; Arowolo, T A; Gbadebo, A M; Idowu, O A</p> <p>2016-06-11</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in our environment are becoming important because of their utilization in permanent magnets, lamp phosphors, superconductors, rechargeable batteries, catalyst, ceramics and other applications. This study was conducted to evaluate the level of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) and the variability of their anomalous behavior in groundwater samples collected from Lagos and Ogun States, Southwest, Nigeria. REE concentrations were determined in 170 groundwater samples using inductively coupled plasma-mass spectrometry, while the physicochemical parameters were determined using standard methods. Lagos State groundwater is enriched with REE [sum REEs range (mean ± SD)]; [0.365-488 (69.5 ± 117)] µg L(-1) than Ogun State groundwater [sum REEs range (mean ± SD)]; [1.14-232 (22.6 ± 41.1)] µg L(-1). Boreholes are more enriched with REEs than wells. Significant (P < 0.05) positive correlation (R = Pearson) was recorded in Lagos State groundwater between sum REEs and Fe (R = 0.55). However, there were no significant correlations between sum REEs, pH (R = 0.073) and HCO3(2-) (R = 0.157) in Ogun State groundwater. Chondrite-normalized plot shows that Lagos groundwater exhibits positive Ce anomaly, while Ogun State groundwater does not. The source of REE in Lagos State may be from the ocean and leaching from wastes dumpsites, while the source in Ogun State groundwater may be from the rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/tei/0148/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/tei/0148/report.pdf"><span>Summary of the research work of the Trace <span class="hlt">Elements</span> Section, <span class="hlt">Geochemistry</span> and Petrology Branch, for the period April 1, 1948-December 31, 1950</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rabbitt, John C.</p> <p>1951-01-01</p> <p>Much of the material in this report has been paraphrased from reports prepared by members of the Section. My special thanks are due them; to Earl Ingerson, chief of the <span class="hlt">Geochemistry</span> and Petrology Branch of the Survey, for his critical review; to my secretary, Marie Woolihan, for her aid in collecting material; and to Virginia Layne of the editorial staff of the Section for typing the manuscript and the multilith mats.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMIN23C1524W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMIN23C1524W"><span>Structural <span class="hlt">Elements</span> in a Persistent Identifier Infrastructure and Resulting Benefits for the <span class="hlt">Earth</span> Science Community</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weigel, T.; Toussaiant, F.; Stockhause, M.; Höck, H.; Kindermann, S.; Lautenschlager, M.; Ludwig, T.</p> <p>2012-12-01</p> <p>We propose a wide adoption of structural <span class="hlt">elements</span> (typed links, collections, trees) in the Handle System to improve identification and access of scientific data, metadata and software as well as traceability of data provenance. Typed links target the issue of data provenance as a means to assess the quality of scientific data. Data provenance is seen here as a directed acyclic graph with nodes representing data and vertices representing derivative operations (Moreau 2010). Landing pages can allow a human user to explore the provenance graph back to the primary unprocessed data, thereby also giving credit to the original data producer. As in <span class="hlt">Earth</span> System Modeling no single infrastructure with complete data lifecycle coverage exists, we propose to split the problem domain in two parts. Project-specific infrastructures such as the German project C3-Grid or the <span class="hlt">Earth</span> System Grid Federation (ESGF) for CMIP5 data are aware of data and data operations (Toussaint et al. 2012) and can thus detect and accumulate single nodes and vertices in the provenance graph, assigning Handles to data, metadata and software. With a common schema for typed links, the provenance graph is established as downstream infrastructures refer incoming Handles. Data in this context is for example hierarchically structured <span class="hlt">Earth</span> System model output data, which receives DataCite DOIs only for the most coarse-granular <span class="hlt">elements</span>. Using Handle tree structures, the lower levels of the hierarchy can also receive Handles, allowing authors to more precisely identify the data they used (Lawrence et al. 2011). We can e.g. define a DOI for just the 2m-temperature variable of CMIP5 data across many CMIP5 experiments or a DOI for model and observational data coming from different sources. The structural <span class="hlt">elements</span> should be implemented through Handle values at the Handle infrastructure level for two reasons. Handle values are more durable than downstream websites or databases, and thus the provenance chain does not</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Litho.248..432F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Litho.248..432F"><span>Seawater-derived rare <span class="hlt">earth</span> <span class="hlt">element</span> addition to abyssal peridotites during serpentinization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frisby, Carl; Bizimis, Michael; Mallick, Soumen</p> <p>2016-04-01</p> <p>Serpentinized abyssal peridotites are evidence for active communication between the <span class="hlt">Earth</span>'s hydrosphere and the upper mantle, where exchange and retention of both major and trace <span class="hlt">elements</span> occur. Bulk rock Nd isotopes in serpentinized abyssal peridotites imply interaction of seawater with the peridotite. In contrast, the Nd isotopes of clinopyroxenes from serpentinized abyssal peridotites retain their primary magmatic signature. It is currently unclear if, how and where seawater-derived Nd and other REE are being added or exchanged with the mantle peridotite minerals during serpentinization. To remedy this knowledge gap, we present in situ trace and major <span class="hlt">element</span> concentrations, bulk rock and sequential leaching experiment trace <span class="hlt">element</span> concentrations as well as Nd, Sr isotope data on refertilized and depleted serpentinized abyssal peridotites from the Southwest Indian Ridge. The secondary serpentine matrix and magnetite veins in these peridotites have elevated LREE concentrations, with variable negative Ce anomalies and large Rb, Sr, Pb and U enrichments that resemble seawater trace <span class="hlt">element</span> patterns. The LREE concentrations in the serpentine phase are higher than those expected for the primary mantle mineralogy (olivine, orthopyroxene) based on data from relic clinopyroxenes and equilibrium partition coefficients. These data are consistent with seawater-derived REE addition to the peridotite during serpentinization. The bulk rocks have more radiogenic Sr and more unradiogenic Nd isotopes than their clinopyroxene (up to 8 εNd units lower than clinopyroxene). Sequential leaching experiments designed to mobilize secondary carbonates and Fe-oxides show even more unradiogenic Nd isotope ratios in the leachates than the bulk rock and clinopyroxene, approaching seawater compositions (up to 15 εNd units lower than clinopyroxene). Mass balance calculations using trace <span class="hlt">elements</span> or Nd isotopes suggest that up to 30% of the bulk peridotite Nd budget is of seawater origin and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.194..123L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.194..123L"><span>The importance of sulfur for the behavior of highly-siderophile <span class="hlt">elements</span> during <span class="hlt">Earth</span>'s differentiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laurenz, Vera; Rubie, David C.; Frost, Daniel J.; Vogel, Antje K.</p> <p>2016-12-01</p> <p>The highly siderophile <span class="hlt">elements</span> (HSEs) are widely used as geochemical tracers for <span class="hlt">Earth</span>'s accretion and core formation history. It is generally considered that core formation strongly depleted the <span class="hlt">Earth</span>'s mantle in HSEs, which were subsequently replenished by a chondritic late veneer. However, open questions remain regarding the origin of suprachondritic Ru/Ir and Pd/Ir ratios that are thought to be characteristic for the primitive upper mantle. In most core-formation models that address the behavior of the HSEs, light <span class="hlt">elements</span> such as S entering the core have not been taken into account and high P-T experimental data for S-bearing compositions are scarce. Here we present a comprehensive experimental study to investigate the effect of increasing S concentration in the metal on HSE metal-silicate partitioning at 2473 K and 11 GPa. We show that the HSEs become less siderophile with increasing S concentrations in the metal, rendering core-forming metal less efficient in removing the HSEs from the mantle if S is present. Furthermore, we investigated the FeS sulfide-silicate partitioning of the HSEs as a function of pressure (7-21 GPa) and temperature (2373-2673 K). The sulfide-silicate partition coefficient for Pt increases strongly with P, whereas those for Pd, Ru and Ir all decrease. The combined effect is such that above ∼20 GPa Ru becomes less chalcophile than Pt, which is opposite to their behavior in the metal-silicate system where Ru is always more siderophile than Pt. The newly determined experimental results are used in a simple 2-stage core formation model that takes into account the effect of S on the behavior of the HSEs during core formation. Results of this model show that segregation of a sulfide liquid to the core from a mantle with substantial HSE concentrations plays a key role in reproducing <span class="hlt">Earth</span>'s mantle HSE abundances. As Ru and Pd are less chalcophile than Pt and Ir at high P-T, some Ru and Pd remain in the mantle after sulfide segregation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....14148P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....14148P"><span>Tracing irradiation-induced defect state of monazite by photoluminescence of rare <span class="hlt">Earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panczer, G.; Seydoux-Guillaume, A. M.; Montel, J. M.; Champagnon, B.</p> <p>2003-04-01</p> <p>Natural monazite is known in contrast to zircon, to almost never be found in the metamict state (Ewing, 1975) despite the fact that it received intensive radiation doses during geologic history by U and Th incorporation. Radiation damages in natural monazite seems to be limited to isolated domains within the crystal (Meldrum et al., 1998). Such property controlled the fact that the monazite lattice is easily healed even at low temperature as it was shown by TEM, XRD and Raman spectrometry (Seydoux-Guillaume et al., 2002). In order to estimate the degree of disorder and the healing of defects we used trivalent neodymium as an internal luminescent probe (Gaft et al., 2001). As a matter of fact the radiative electronic transitions of rare <span class="hlt">earth</span> <span class="hlt">elements</span> are very sensible to the short-range crystallographic order around them. Three natural monazites thermally untreated and quenched at 450, 500, 700, 800 and 1000^oC were analyzed under 514 nm Argon laser excitation with a Renishaw microspectrometer. Nd3+ emission was recorded in the range of 750 nm to 1 μm. The ^4F3/2 rightarrow ^4I9/2 transition parameters (position and width) show that 1) the position of the Stark levels do not change during thermal treatment, and 2) that the emission line widths decrease continuously (from 25 to 37%) from room temperature to 1000^oC. These results indicates that before annealing, sub sites of Nd were present with slight different environments induced by internal irradiation induced displacement of ions around them (short range disorder). After thermal treatment a continuous reorganization of the lattice occurs up to 1000^oC with quite strong rearrangement of the environment around the rare-<span class="hlt">earth</span> leading to a decrease of the Nd sub site number. Thus, the luminescent probe reveals that defect healing continue at much higher temperatures than what was previously reported indicating that luminescence is a very sensible tool to appreciate the degree of disorder in mineral phases. Gaft M</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710235D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710235D"><span>Developing alternative resources of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Europe - EURARE and the red mud challenge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deady, Eimear; Mouchos, Evangelos; Goodenough, Kathryn; Wall, Frances; Williamson, Ben</p> <p>2015-04-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">earth</span> <span class="hlt">elements</span> 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 Seydişehir-Akseki region of Turkey have been assessed as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V42A..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V42A..01C"><span>Subduction Zone Redox and the Deep <span class="hlt">Earth</span> Cycles of Sulfur and Chalcophile <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Canil, D.</p> <p>2013-12-01</p> <p>Subduction at convergent plate margins is a return flux to the mantle of rocks influenced by weathering, hydrothermal activity, atmospheric exchange, or bio-mineralization in the exosphere. The latter exogenic processes modify the long-term abundance and behaviour of certain <span class="hlt">elements</span> in the deeper <span class="hlt">earth</span> that can be traced over time in the chemistry of mantle-derived magmas. The redox budget of subduction is controlled by the flux of oxidized versus reduced forms of Fe, S, H, or C, and impacts the long-term evolution of oxygen on the planet, critical for life in the exosphere. In particular, the sulfur cycle is specifically tied to the evolution of oxygen on <span class="hlt">Earth</span>'s surface over time and critical to biogeochemical cycles on the surface. The behaviour of sulfur in the exogenic system is well-studied and fairly well understood using sedimentary records. An originally sulfidic ocean on <span class="hlt">Earth</span> gave way with time and oxygenation to one that is sulfate dominated over the last two billion years. In contrast, far less is known of the deep <span class="hlt">earth</span> cycle of S, and more so its history. The record of the endogenic cycle can only be monitored via what comes out of the mantle (magmas and their gases), or what goes down via subduction (hydrothermally-altered or weathered subducted lithosphere). Interest in the endogenic cycle of S is not new but several outstanding conundrums remain for sulfur in arc magmas that point to the importance of the subduction process. A hitherto ignored component of the paradox of the sulfur cycle is the sedimentary veneer that sits atop the subducted oceanic basalt crust. Compilations show only 0.12 wt% S in altered ocean basalt crust, but up to 10 times that amount in oceanic sediments, tied to their Fe content (in pyrite). These abundances may seem trivial, but the behaviour of this small amount of S in subduction is not fully appreciated and its oxidation potential in the arc mantle is enormous. The conversion of subducted sulfide to sulfate is a 8</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25710372','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25710372"><span>A new fungal isolate, Penidiella sp. strain T9, accumulates the rare <span class="hlt">earth</span> <span class="hlt">element</span> dysprosium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Horiike, Takumi; Yamashita, Mitsuo</p> <p>2015-05-01</p> <p>With an aim to develop a highly efficient method for the recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 μg/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 <span class="hlt">elemental</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28303615','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28303615"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> and select actinoids in the Canadian House Dust Study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rasmussen, P E; Levesque, C; Chénier, M; Gardner, H D</p> <p>2017-03-17</p> <p>Nationally representative baseline data are presented for rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE), thorium (Th) and uranium (U) in house dust sampled from 1025 urban homes, in units of concentrations (μg g(-1) ), loadings (μg m(-2) ), and loading rates (ng m(-2)  d(-1) ). Spearman rank correlations indicate that, in addition to outdoor sources, consumer products and building materials can influence indoor dust concentrations of REE, Th, and U. Correlations (P<.01) with numbers of occupants, dogs, and cats suggest soil track-in. Correlations (P<.01) with hardwood floors suggest release of REE additives used in pigments and coatings during daily wear and tear. Concentrations of light REE are elevated in smokers' homes compared to non-smokers' homes (P<.001), suggesting that a key source is "mischmetal," the REE alloy used in cigarette-lighter flints. Indoor sources include geological impurities in raw materials used in consumer products, such as U and Th impurities in bentonite clay used in cat litter, and REE impurities in phosphates used for a variety of applications including dog food and building materials. Median gastric bioaccessibility (pH 1.5) of most REE in dust ranges from about 20% to 29%. Household vacuum samples correlate with fresh dust samples from the same homes (P<.001 for all investigated <span class="hlt">elements</span>).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991RSPSA.433..121K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991RSPSA.433..121K"><span>Analytical Approach Using KS <span class="hlt">Elements</span> to Near-<span class="hlt">Earth</span> Orbit Predictions Including Drag</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krishnan Sharma, Ram</p> <p>1991-04-01</p> <p>A new analytical theory for the motion of near-<span class="hlt">Earth</span> satellite orbits with the air drag effect is developed in terms of the KS <span class="hlt">elements</span>, utilizing an analytical oblate exponential atmospheric density model. Due to the symmetry of the KS <span class="hlt">element</span> equations, only one of the eight equations is integrated analytically to obtain the state vector at the end of each revolution. This is a uniqueness of the present theory. The series expansions include up to quadratic terms in e (eccentricity) and c (a small parameter dependent on the flattening of the atmosphere). Numerical studies are done with six test cases, selected to cover a wide range of eccentricity and semi-major axis, and a comparison of the three orbital parameters: semi-major axis, eccentricity and argument of perigee perturbed by the air drag with oblate atmosphere is made up to 100 revolutions with the numerically integrated values. The comparison is quite satisfactory. After 100 revolutions, with a ballistic coefficient of 50, a maximum difference of 39 metres is found in the semi-major axis comparison for a very small eccentricity (0.001) case having an initial perigee height of 391.425 km. One important advantage of the present theory is that it is singularity free, a problem faced by the analytical theories developed from the Lagrange's planetary equations. Another advantage is that the state vector is known after each revolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4393457','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4393457"><span>A New Fungal Isolate, Penidiella sp. Strain T9, Accumulates the Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Dysprosium</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Horiike, Takumi</p> <p>2015-01-01</p> <p>With an aim to develop a highly efficient method for the recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 μg/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 <span class="hlt">elemental</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28230202','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28230202"><span>Ecosystem Composition Controls the Fate of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> during Incipient Soil Genesis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zaharescu, Dragos G; Burghelea, Carmen I; Dontsova, Katerina; Presler, Jennifer K; Maier, Raina M; Huxman, Travis; Domanik, Kenneth J; Hunt, Edward A; Amistadi, Mary K; Gaddis, Emily E; Palacios-Menendez, Maria A; Vaquera-Ibarra, Maria O; Chorover, Jon</p> <p>2017-02-23</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are increasingly important in a variety of science and economic fields, including (bio)geosciences, paleoecology, astrobiology, and mining. However, REE distribution in early rock-microbe-plant systems has remained elusive. We tested the hypothesis that REE mass-partitioning during incipient weathering of basalt, rhyolite, granite and schist depends on the activity of microbes, vascular plants (Buffalo grass), and arbuscular mycorrhiza. Pore-water <span class="hlt">element</span> abundances revealed a rapid transition from abiotic to biotic signatures of weathering, the latter associated with smaller aqueous loss and larger plant uptake. Abiotic dissolution was 39% of total denudation in plant-microbes-mycorrhiza treatment. Microbes incremented denudation, particularly in rhyolite, and this resulted in decreased bioavailable solid pools in this rock. Total mobilization (aqueous + uptake) was ten times greater in planted compared to abiotic treatments, REE masses in plant generally exceeding those in water. Larger plants increased bioavailable solid pools, consistent with enhanced soil genesis. Mycorrhiza generally had a positive effect on total mobilization. The main mechanism behind incipient REE weathering was carbonation enhanced by biotic respiration, the denudation patterns being largely dictated by mineralogy. A consistent biotic signature was observed in La:phosphate and mobilization: solid pool ratios, and in the pattern of denudation and uptake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatSR...743208Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatSR...743208Z"><span>Ecosystem Composition Controls the Fate of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> during Incipient Soil Genesis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaharescu, Dragos G.; Burghelea, Carmen I.; Dontsova, Katerina; Presler, Jennifer K.; Maier, Raina M.; Huxman, Travis; Domanik, Kenneth J.; Hunt, Edward A.; Amistadi, Mary K.; Gaddis, Emily E.; Palacios-Menendez, Maria A.; Vaquera-Ibarra, Maria O.; Chorover, Jon</p> <p>2017-02-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are increasingly important in a variety of science and economic fields, including (bio)geosciences, paleoecology, astrobiology, and mining. However, REE distribution in early rock-microbe-plant systems has remained elusive. We tested the hypothesis that REE mass-partitioning during incipient weathering of basalt, rhyolite, granite and schist depends on the activity of microbes, vascular plants (Buffalo grass), and arbuscular mycorrhiza. Pore-water <span class="hlt">element</span> abundances revealed a rapid transition from abiotic to biotic signatures of weathering, the latter associated with smaller aqueous loss and larger plant uptake. Abiotic dissolution was 39% of total denudation in plant-microbes-mycorrhiza treatment. Microbes incremented denudation, particularly in rhyolite, and this resulted in decreased bioavailable solid pools in this rock. Total mobilization (aqueous + uptake) was ten times greater in planted compared to abiotic treatments, REE masses in plant generally exceeding those in water. Larger plants increased bioavailable solid pools, consistent with enhanced soil genesis. Mycorrhiza generally had a positive effect on total mobilization. The main mechanism behind incipient REE weathering was carbonation enhanced by biotic respiration, the denudation patterns being largely dictated by mineralogy. A consistent biotic signature was observed in La:phosphate and mobilization: solid pool ratios, and in the pattern of denudation and uptake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27447714','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27447714"><span>Distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soil and grape berries of Vitis vinifera cv. "Glera".</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pepi, Salvatore; Sansone, Luigi; Chicca, Milvia; Marrocchino, Elena; Vaccaro, Carmela</p> <p>2016-08-01</p> <p>The renowned Vitis vinifera L. cultivar "Glera" (Magnoliopsida Vitaceae) has been grown for hundreds of years in the Italian regions of Veneto and Friuli to produce the sparkling Prosecco wine, with controlled designation of origin (DOC). We evaluated the relationship among the concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in soil and in "Glera" grape berries in vineyards belonging to five different localities in the Veneto alluvial plain, all included in the DOC area of Prosecco. The concentration of REE in samples of soil and juice or solid residues of grape berries was determined by inductively coupled plasma mass spectrometry (ICP-MS), and the index of bioaccumulation was calculated to define the specific assimilation of these <span class="hlt">elements</span> from soil to grape berries. The concentration of REE in soil samples allowed an identification of each locality examined, and REE were mostly detected in solid grape berry residues in comparison to juice. These data may be useful to associate REE distribution in soil and grape berries to a specific geographical origin, in order to prevent fraudulent use of wine denomination labels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16290296','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16290296"><span>Using rare <span class="hlt">earth</span> <span class="hlt">element</span> tracers and neutron activation analysis to study rill erosion process.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Mian; Li, Zhan-bin; Ding, Weng-feng; Liu, Pu-ling; Yao, Wen-yi</p> <p>2006-03-01</p> <p>Spatially averaged soil erosion data provide little information on the process of rill erosion. The dynamically varied data on the temporal and spatial distributions in the rill erosion process are needed to better understand the erosion process and reveal its innate characteristics. The objectives of this study were to examine the feasibility and effectiveness of rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) tracers and the neutron activation analysis (NAA) method on the study of the rill erosion process and to reveal quantitatively the relationships and characteristics of temporal and spatial distributions of sediment yield in rill erosion. Four REEs were used to study the changeable process of rill erosion at 4 slope positions. Four water inflow rates were applied to a 0.3 x 5 m soil bed at 3 slopes of 10.5%, 15.8% and 21.2% in scouring experiments. All of the runoff was collected in the experiment. Each sample was air-dried and well mixed. Then 20 g of each sample was sieved through 100-mesh and about a 50 mg sample was weighed for analysis of the four <span class="hlt">elemental</span> compositions by NAA. Results indicate that the REE tracers and NAA method can be used to not only quantitatively determine soil erosion amounts on different slope segments, but also to reveal the changeable process of rill erosion amount. All of the relative errors of the experimental results were less than 25%, which is considered satisfactory on the study of rill erosion process.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28056169','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28056169"><span>Concomitant Leaching and Electrochemical Extraction of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from Monazite.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maes, Synthia; Zhuang, Wei-Qin; Rabaey, Korneel; Alvarez-Cohen, Lisa; Hennebel, Tom</p> <p>2017-02-07</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have become increasingly important in modern day technologies. Unfortunately, their recycling is currently limited, and the conventional technologies for their extraction and purification are exceedingly energy and chemical intensive. New sustainable technologies for REE extraction from both primary and secondary resources would be extremely beneficial. This research investigated a two-stage recovery strategy focused on the recovery of neodymium (Nd) and lanthanum (La) from monazite ore that combines microbially based leaching (using citric acid and spent fungal supernatant) with electrochemical extraction. Pretreating the phosphate-based monazite rock (via roasting) dramatically increased the microbial REE leaching efficiency. Batch experiments demonstrated the effective and continued leaching of REEs by recycled citric acid, with up to 392 mg of Nd L(-1) and 281 mg of La L(-1) leached during seven consecutive 24 h cycles. Neodymium was further extracted in the catholyte of a three-compartment electrochemical system, with up to 880 mg of Nd L(-1) achieved within 4 days (at 40 A m(-2)). Meanwhile, the radioactive <span class="hlt">element</span> thorium and counterions phosphate and citrate were separated effectively from the REEs in the anolyte, favoring REE extraction and allowing sustainable reuse of the leaching agent. This study shows a promising technology that is suitable for primary ores and can further be optimized for secondary resources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5322375','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5322375"><span>Ecosystem Composition Controls the Fate of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> during Incipient Soil Genesis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zaharescu, Dragos G.; Burghelea, Carmen I.; Dontsova, Katerina; Presler, Jennifer K.; Maier, Raina M.; Huxman, Travis; Domanik, Kenneth J.; Hunt, Edward A.; Amistadi, Mary K.; Gaddis, Emily E.; Palacios-Menendez, Maria A.; Vaquera-Ibarra, Maria O.; Chorover, Jon</p> <p>2017-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are increasingly important in a variety of science and economic fields, including (bio)geosciences, paleoecology, astrobiology, and mining. However, REE distribution in early rock-microbe-plant systems has remained elusive. We tested the hypothesis that REE mass-partitioning during incipient weathering of basalt, rhyolite, granite and schist depends on the activity of microbes, vascular plants (Buffalo grass), and arbuscular mycorrhiza. Pore-water <span class="hlt">element</span> abundances revealed a rapid transition from abiotic to biotic signatures of weathering, the latter associated with smaller aqueous loss and larger plant uptake. Abiotic dissolution was 39% of total denudation in plant-microbes-mycorrhiza treatment. Microbes incremented denudation, particularly in rhyolite, and this resulted in decreased bioavailable solid pools in this rock. Total mobilization (aqueous + uptake) was ten times greater in planted compared to abiotic treatments, REE masses in plant generally exceeding those in water. Larger plants increased bioavailable solid pools, consistent with enhanced soil genesis. Mycorrhiza generally had a positive effect on total mobilization. The main mechanism behind incipient REE weathering was carbonation enhanced by biotic respiration, the denudation patterns being largely dictated by mineralogy. A consistent biotic signature was observed in La:phosphate and mobilization: solid pool ratios, and in the pattern of denudation and uptake. PMID:28230202</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SedG..343...56F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SedG..343...56F"><span>Trace <span class="hlt">elements</span> and REE <span class="hlt">geochemistry</span> of Middle Devonian carbonate mounds (Maïder Basin, Eastern Anti-Atlas, Morocco): Implications for early diagenetic processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Franchi, Fulvio; Turetta, Clara; Cavalazzi, Barbara; Corami, Fabiana; Barbieri, Roberto</p> <p>2016-08-01</p> <p>Trace and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have proven their utility as tools for assessing the genesis and early diagenesis of widespread geological bodies such as carbonate mounds, whose genetic processes are not yet fully understood. Carbonates from the Middle Devonian conical mud mounds of the Maïder Basin (eastern Anti-Atlas, Morocco) have been analysed for their REE and trace <span class="hlt">element</span> distribution. Collectively, the carbonates from the Maïder Basin mud mounds appear to display coherent REE patterns. Three different geochemical patterns, possibly related with three different diagenetic events, include: i) dyke fills with a normal marine REE pattern probably precipitated in equilibrium with seawater, ii) mound micrite with a particular enrichment of overall REE contents and variable Ce anomaly probably related to variation of pH, increase of alkalinity or dissolution/remineralization of organic matter during early diagenesis, and iii) haematite-rich vein fills precipitated from venting fluids of probable hydrothermal origin. Our results reinforce the hypothesis that these mounds were probably affected by an early diagenesis induced by microbial activity and triggered by abundance of dispersed organic matter, whilst venting may have affected the mounds during a later diagenetic phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1112002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1112002M"><span>Using rare <span class="hlt">earth</span> <span class="hlt">elements</span> for the identification of the geographic origin of food</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meisel, T.; Bandoniene, D.; Joebstl, D.</p> <p>2009-04-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">element</span> and rare <span class="hlt">earth</span> 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 <span class="hlt">element</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23978671','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23978671"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs): effects on germination and growth of selected crop and native plant species.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thomas, Philippe J; Carpenter, David; Boutin, Céline; Allison, Jane E</p> <p>2014-02-01</p> <p>The phytotoxicity of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">element</span> 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 <span class="hlt">elements</span> in the environment could become problematic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010CoMP..160..761O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010CoMP..160..761O"><span>Rare <span class="hlt">earth</span> and high field strength <span class="hlt">element</span> partitioning between iron-rich clinopyroxenes and felsic liquids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olin, P. H.; Wolff, J. A.</p> <p>2010-11-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">element</span> partitioning that is detectable among pairs of isovalent <span class="hlt">elements</span> with near-identical radii, such as Y and Ho, Zr and Hf, and Nb and Ta.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMEP51B0585E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMEP51B0585E"><span>Spatial and temporal dynamics of sediment in contrasted mountainous watersheds (Mexican transvolcanic belt and French Southern Alps) combining river gauging, <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> and fallout radionuclides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evrard, O.; Navratil, O.; Gratiot, N.; Némery, J.; Duvert, C.; Ayrault, S.; Lefèvre, I.; Legout, C.; Bonté, P.; Esteves, M.</p> <p>2009-12-01</p> <p>In mountainous environments, an excessive fine sediment supply to the rivers typically leads to an increase in water turbidity, contaminant transport and a rapid filling of reservoirs. This situation is particularly problematic in regions where water reservoirs are used to provide drinking water to large cities (e.g. in central Mexico) or where stream water is used to run hydroelectric power plants (e.g. in the French Southern Alps). In such areas, sediment source areas first need to be delineated and sediment fluxes between hillslopes and the river system must be better understood before implementing efficient erosion control measures. In this context, the STREAMS (« Sediment Transport and Erosion Across MountainS ») project funded by the French National Research Agency (ANR) aims at understanding the spatial and temporal dynamics of sediment at the scale of mountainous watersheds (between 500 - 1000 km2) located in contrasted environments. This 3-years study is carried out simultaneously in a volcanic watershed located in the Mexican transvolcanic belt undergoing a subhumid tropical climate, as well as in a sedimentary watershed of the French Southern Alps undergoing a transitional climate with Mediterranean and continental influences. One of the main specificities of this project consists in combining traditional monitoring techniques (i.e. installation of river gauges, turbidimeters and sediment samplers in several sub-catchments) and sediment fingerprinting using <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> (measured by Instrumental Neutron Activation Analysis - INAA - and Inductively Coupled Plasma - Mass Spectrometry - ICP-MS) and fallout radionuclides (measured by gamma spectrometry). In the French watershed, geochemical analysis allows outlining different sediment sources (e.g. the contribution of calcareous vs. marl-covered sub-watersheds). Radionuclide ratios (e.g.Be-7/Cs-137) allow identifying the dominant erosion processes occurring within the watershed. Areas mostly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27451177','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27451177"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> minimal harvest year variation facilitates robust geographical origin discrimination: The case of PDO "Fava Santorinis".</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Drivelos, Spiros A; Danezis, Georgios P; Haroutounian, Serkos A; Georgiou, Constantinos A</p> <p>2016-12-15</p> <p>This study examines the trace and rare <span class="hlt">earth</span> <span class="hlt">elemental</span> (REE) fingerprint variations of PDO (Protected Designation of Origin) "Fava Santorinis" over three consecutive harvesting years (2011-2013). Classification of samples in harvesting years was studied by performing discriminant analysis (DA), k nearest neighbours (κ-NN), partial least squares (PLS) analysis and probabilistic neural networks (PNN) using rare <span class="hlt">earth</span> <span class="hlt">elements</span> and trace metals determined using ICP-MS. DA performed better than κ-NN, producing 100% discrimination using trace <span class="hlt">elements</span> and 79% using REEs. PLS was found to be superior to PNN, achieving 99% and 90% classification for trace and REEs, respectively, while PNN achieved 96% and 71% classification for trace and REEs, respectively. The information obtained using REEs did not enhance classification, indicating that REEs vary minimally per harvesting year, providing robust geographical origin discrimination. The results show that seasonal patterns can occur in the <span class="hlt">elemental</span> composition of "Fava Santorinis", probably reflecting seasonality of climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23150591','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23150591"><span>Carbon and other light <span class="hlt">element</span> contents in the <span class="hlt">Earth</span>'s core based on first-principles molecular dynamics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yigang; Yin, Qing-Zhu</p> <p>2012-11-27</p> <p>Carbon (C) is one of the candidate light <span class="hlt">elements</span> proposed to account for the density deficit of the <span class="hlt">Earth</span>'s core. In addition, C significantly affects siderophile and chalcophile <span class="hlt">element</span> partitioning between metal and silicate and thus the distribution of these <span class="hlt">elements</span> in the <span class="hlt">Earth</span>'s core and mantle. Derivation of the accretion and core-mantle segregation history of the <span class="hlt">Earth</span> requires, therefore, an accurate knowledge of the C abundance in the <span class="hlt">Earth</span>'s core. Previous estimates of the C content of the core differ by a factor of ∼20 due to differences in assumptions and methods, and because the metal-silicate partition coefficient of C was previously unknown. Here we use two-phase first-principles molecular dynamics to derive this partition coefficient of C between liquid iron and silicate melt. We calculate a value of 9 ± 3 at 3,200 K and 40 GPa. Using this partition coefficient and the most recent estimates of bulk <span class="hlt">Earth</span> or mantle C contents, we infer that the <span class="hlt">Earth</span>'s core contains 0.1-0.7 wt% of C. Carbon thus plays a moderate role in the density deficit of the core and in the distribution of siderophile and chalcophile <span class="hlt">elements</span> during core-mantle segregation processes. The partition coefficients of nitrogen (N), hydrogen, helium, phosphorus, magnesium, oxygen, and silicon are also inferred and found to be in close agreement with experiments and other geochemical constraints. Contents of these <span class="hlt">elements</span> in the core derived from applying these partition coefficients match those derived by using the cosmochemical volatility curve and geochemical mass balance arguments. N is an exception, indicating its retention in a mantle phase instead of in the core.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21087157','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21087157"><span>The formation of sulfate and <span class="hlt">elemental</span> sulfur aerosols under varying laboratory conditions: implications for early <span class="hlt">earth</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>DeWitt, H Langley; Hasenkopf, Christa A; Trainer, Melissa G; Farmer, Delphine K; Jimenez, Jose L; McKay, Christopher P; Toon, Owen B; Tolbert, Margaret A</p> <p>2010-10-01</p> <p>The presence of sulfur mass-independent fractionation (S-MIF) in sediments more than 2.45 × 10(9) years old is thought to be evidence for an early anoxic atmosphere. Photolysis of sulfur dioxide (SO(2)) by UV light with λ < 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 <span class="hlt">elemental</span> sulfur (S(8)) and sulfuric acid (H(2)SO(4)) aerosols. Here, we use real-time aerosol mass spectrometry to directly detect the sulfur-containing aerosols formed when SO(2) 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 (H(2)) or methane (CH(4)), increased the formation of S(8). With UV photolysis, formation of S(8) aerosols is highly dependent on the initial SO(2) pressure; and S(8) is only formed at a 2% SO(2) mixing ratio and greater in the absence of a reductant, and at a 0.2% SO(2) mixing ratio and greater in the presence of 1000 ppmv CH(4). We also found that organosulfur compounds are formed from the photolysis of CH(4) and moderate amounts of SO(2). The implications for sulfur aerosols on early <span class="hlt">Earth</span> are discussed. Key Words: S-MIF-Archean atmosphere-Early <span class="hlt">Earth</span>-Sulfur aerosols.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MinDe..49..987M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MinDe..49..987M"><span>Hydrothermal transport and deposition of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> by fluorine-bearing aqueous liquids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Migdisov, Art A.; Williams-Jones, A. E.</p> <p>2014-12-01</p> <p>New technologies, particularly those designed to address environmental concerns, have created a great demand for the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE), and focused considerable attention on the processes by which they are concentrated to economically exploitable levels in the <span class="hlt">Earth</span>'s crust. There is widespread agreement that hydrothermal fluids played an important role in the formation of the world's largest economic REE deposit, i.e. Bayan Obo, China. Until recently, many researchers have assumed that hydrothermal transport of the REE in fluorine-bearing ore-forming systems occurs mainly due to the formation of REE-fluoride complexes. Consequently, hydrothermal models for REE concentration have commonly involved depositional mechanisms based on saturation of the fluid with REE minerals due to destabilization of REE-fluoride complexes. Here, we demonstrate that these complexes are insignificant in REE transport, and that the above models are therefore flawed. The strong association of H+ and F- as HF° and low solubility of REE-F solids greatly limit transport of the REE as fluoride complexes. However, this limitation does not apply to REE-chloride complexes. Because of this, the high concentration of Cl- in the ore fluids, and the relatively high stability of REE-chloride complexes, the latter can transport appreciable concentrations of REE at low pH. The limitation also does not apply to sulphate complexes and in some fluids, the concentration of sulphate may be sufficient to transport significant concentrations of REE as sulphate complexes, particularly at weakly acidic pH. This article proposes new models for hydrothermal REE deposition based on the transport of the REE as chloride and sulphate complexes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23914548','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23914548"><span>[Effects of arbuscular mycorrhizal fungi on the growth and rare <span class="hlt">earth</span> <span class="hlt">elements</span> uptake of soybean grown in rare <span class="hlt">earth</span> mine tailings].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guo, Wei; Zhao, Ren-xin; Zhao, Wen-jing; Fu, Rui-ying; Guo, Jiang-yuan; Zhang, Jun</p> <p>2013-05-01</p> <p>A greenhouse pot experiment was conducted to investigate the influence of arbuscular mycorrhizal (AM) fungi Glomus versiforme on the plant growth, nutrient uptake, C: N: P stoichiometric, uptake of heavy metals and rare <span class="hlt">earth</span> <span class="hlt">elements</span> by soybean (Glycine max) grown in rare <span class="hlt">earth</span> mine tailings. The aim was to provide a basis for the revegetation of rare <span class="hlt">earth</span> mine tailings. The results indicated that soybean had a high mycorrhizal colonization and symbiotic associations were successfully established with G. versiforme, with an average rate of approximately 67%. The colonization of G. versiforme significantly promoted the growth of soybean, increased P, K contents, and decreased C: N: P ratios, supporting the growth rate hypothesis. Inoculation with G. versiforme significantly decreased shoots and roots La, Ce, Pr and Nd concentrations of soybean compared to the control treatment. However, inoculation with G. versiforme had no significant effect on the heavy metal concentrations, except for significantly decreased shoot Fe and Cr concentrations and increased root Cd concentrations. The experiment demonstrates that AM fungi have a potential role for soybean to adapt the composite adversity of rare <span class="hlt">earth</span> tailings and play a positive role in revegetation of rare <span class="hlt">earth</span> mine tailings. Further studies on the role of AM fungi under natural conditions should be conducted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014E%26PSL.398..101T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.398..101T"><span>Efficient mobilization and fractionation of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> by aqueous fluids upon slab dehydration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsay, A.; Zajacz, Z.; Sanchez-Valle, C.</p> <p>2014-07-01</p> <p>The characteristic REE fractionation pattern in arc magmas compared to MOR-basalts results from the selective mobilization of light rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (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-<span class="hlt">earth</span> <span class="hlt">elements</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22472534','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22472534"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> and critical metal content of extracted landfilled material and potential recovery opportunities</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gutiérrez-Gutiérrez, Silvia C.; Coulon, Frédéric; Jiang, Ying; Wagland, Stuart</p> <p>2015-08-15</p> <p>Highlights: • Samples from multiple core drills were obtained from 4× landfill sites in the UK. • Each sample analysed for rare <span class="hlt">earth</span> <span class="hlt">elements</span>, critical metals and valuable metals. • Two stage microwave digestion method ensuring high yield. • High quantities of copper and aluminium were observed in the soil layers of landfill. • Across 4× landfills aluminium and copper present has a value of around $400 million. - Abstract: Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 ± 6 mg kg{sup −1} for REEs comprising 44 ± 8 mg kg{sup −1} for light REEs, 11 ± 2 mg kg{sup −1} for heavy REEs and 3 ± 1 mg kg{sup −1} for Scandium (Sc) and 3 ± 1.0 mg kg{sup −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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1615804M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1615804M"><span>Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> enrichment of Pacific seafloor sediments: the view from volcanic islands of Polynesia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Melleton, Jérémie; Tuduri, Johann; Pourret, Olivier; Bailly, Laurent; Gisbert, Thierry</p> <p>2014-05-01</p> <p>Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1191943-utilizing-rare-earth-elements-tracers-high-tds-reservoir-brines-ccs-applications','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1191943-utilizing-rare-earth-elements-tracers-high-tds-reservoir-brines-ccs-applications"><span>Utilizing rare <span class="hlt">earth</span> <span class="hlt">elements</span> as tracers in high TDS reservoir brines in CCS applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>McLing, Travis; Smith, William; Smith, Robert</p> <p>2014-12-31</p> <p>In this paper we report the result of research associated with the testing of a procedures necessary for utilizing natural occurring trace <span class="hlt">elements</span>, specifically the Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) as geochemical tracers in Carbon Capture and Storage (CCS) applications. Trace <span class="hlt">elements</span>, particularly REE may be well suited to serve as in situ tracers for monitoring geochemical conditions and the migration of CO₂-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 <span class="hlt">elements</span> 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 CO₂. 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 CO₂ 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 CO₂ 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1191943','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1191943"><span>Utilizing rare <span class="hlt">earth</span> <span class="hlt">elements</span> as tracers in high TDS reservoir brines in CCS applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McLing, Travis; Smith, William; Smith, Robert</p> <p>2014-12-31</p> <p>In this paper we report the result of research associated with the testing of a procedures necessary for utilizing natural occurring trace <span class="hlt">elements</span>, specifically the Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) as geochemical tracers in Carbon Capture and Storage (CCS) applications. Trace <span class="hlt">elements</span>, particularly REE may be well suited to serve as <i>in situ</i> tracers for monitoring geochemical conditions and the migration of CO₂-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 <span class="hlt">elements</span> have been successfully used as <i>in situ</i> 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 CO₂. 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 CO₂ 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 CO₂ 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 <i>in situ</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1261974','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1261974"><span>Drill core major, trace and rare <span class="hlt">earth</span> <span class="hlt">element</span> anlayses from wells RN-17B and RN-30, Reykjanes, Iceland</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Andrew Fowler</p> <p>2015-04-01</p> <p>Analytical results for X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) measurement of major, trace and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in drill core from geothermal wells in Reykjanes, Iceland. Total Fe was analyzed as FeO, therefore is not included under the Fe2O3 column.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=271700','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=271700"><span>Using Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> (REE) tracers to identify perferential micro-sites of post-fire aeolian erosion</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Plant communities in desert environments are spatially anisotropic. We applied Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> (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...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70009869','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70009869"><span>A chemical-spectrochemical method for the determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and thorium in cerium minerals</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rose, H.J.; Murata, K.J.; Carron, M.K.</p> <p>1954-01-01</p> <p>In a combined chemical-spectrochemical procedure for quantitatively determining rare <span class="hlt">earth</span> <span class="hlt">elements</span> in cerium minerals, cerium is determined volumetrically, a total rare <span class="hlt">earths</span> 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 <span class="hlt">earths</span> and with samples of chemically analyzed cerium minerals show that the coefficient of variation for a quadruplicate determination of any <span class="hlt">element</span> does not exceed 5??0 (excepting yttrium at concentrations less than 1 percent) and that the method is free of serious systematic error. ?? 1954.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25679485','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25679485"><span>Health effects and toxicity mechanisms of rare <span class="hlt">earth</span> <span class="hlt">elements</span>-Knowledge gaps and research prospects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pagano, Giovanni; Guida, Marco; Tommasi, Franca; Oral, Rahime</p> <p>2015-05-01</p> <p>In the recent decades, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">elements</span>. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28223076','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28223076"><span>Leaching of rare <span class="hlt">earth</span> <span class="hlt">elements</span> from fluorescent powder using the tea fungus Kombucha.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hopfe, Stefanie; Flemming, Katrin; Lehmann, Falk; Möckel, Robert; Kutschke, Sabine; Pollmann, Katrin</p> <p>2017-02-17</p> <p>In most modern technologies such as flat screens, highly effective magnets and lasers, as well as luminescence phosphors, Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) are used. Unfortunately no environmentally friendly recycling process exists so far. In comparison to other <span class="hlt">elements</span> the interaction of microorganisms with REE has been studied to a less extent. However, as REE are ubiquitously present in nature it can be assumed that microorganisms play an important role in the biogeochemistry of REE. This study investigates the potential of organic acid-producing microbes for extracting REE from industrial waste. In Germany, 175 tons of fluorescent phosphor (FP) are collected per year as a distinct fraction from the recycling of compact fluorescent lamps. Because the FP contains about 10% of REE-oxides bound in the so-called triband dyes it is a readily accessible secondary resource of REE. Using the symbiotic mixed culture Kombucha, consisting of yeasts and acetic acid bacteria, REE were leached at a significant rate. The highest leaching-rates were observed in shake cultures using the entire Kombucha-consortium or its supernatant as leaching agent compared to experiments using the isolates Zygosaccharomyces lentus and Komagataeibacter hansenii as leaching organisms. During the cultivation, the pH decreased as a result of organic acid production (mainly acetic and gluconic acid). Thus, the underlying mechanism of the triband dye solubilisation is probably linked to the carboxyl-functionality or a proton excess. In accordance with the higher solubility of REE-oxides compared to REE-phosphates and -aluminates, the red dye Y2O3:Eu(2+) containing relatively expensive REE was shown to be preferentially solubilized. These results show that it is possible to dissolve the REE-compounds of FP with the help of microbial processes. Moreover, they provide the basis for the development of an eco-friendly alternative to the currently applied methods that use strong inorganic acids or toxic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27228215','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27228215"><span>Trends in the Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Content of U.S.-Based Coal Combustion Fly Ashes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Taggart, Ross K; Hower, James C; Dwyer, Gary S; Hsu-Kim, Heileen</p> <p>2016-06-07</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are critical and strategic materials in the defense, energy, electronics, and automotive industries. The reclamation of REEs from coal combustion fly ash has been proposed as a way to supplement REE mining. However, the typical REE contents in coal fly ash, particularly in the United States, have not been comprehensively documented or compared among the major types of coal feedstocks that determine fly ash composition. The objective of this study was to characterize a broad selection of U.S. fly ashes of varied geological origin in order to rank their potential for REE recovery. The total and nitric acid-extractable REE content for more than 100 ash samples were correlated with characteristics such as the major <span class="hlt">element</span> content and coal basin to elucidate trends in REE enrichment. Average total REE content (defined as the sum of the lanthanides, yttrium, and scandium) for ashes derived from Appalachian sources was 591 mg kg(-1) and significantly greater than in ashes from Illinois and Powder River basin coals (403 and 337 mg kg(-1), respectively). The fraction of critical REEs (Nd, Eu, Tb, Dy, Y, and Er) in the fly ashes was 34-38% of the total and considerably higher than in conventional ores (typically less than 15%). Powder River Basin ashes had the highest extractable REE content, with 70% of the total REE recovered by heated nitric acid digestion. This is likely due to the higher calcium content of Powder River Basin ashes, which enhances their solubility in nitric acid. Sc, Nd, and Dy were the major contributors to the total REE value in fly ash, based on their contents and recent market prices. Overall, this study shows that coal fly ash production could provide a substantial domestic supply of REEs, but the feasibility of recovery depends on the development of extraction technologies that could be tailored to the major mineral content and origins of the feed coal for the ash.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013652','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013652"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the phosphatic-enriched sediment of the Peru shelf</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Piper, D.Z.; Baedecker, P.A.; Crock, J.G.; Burnett, W.C.; Loebner, B.J.</p> <p>1988-01-01</p> <p>Apatite-enriched materials from the Peru shelf have been analyzed for their major oxide and rare <span class="hlt">earth</span> <span class="hlt">element</span> (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 <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27081794','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27081794"><span>Responses of plant calmodulin to endocytosis induced by rare <span class="hlt">earth</span> <span class="hlt">elements</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Lihong; Cheng, Mengzhu; Chu, Yunxia; Li, Xiaodong; Chen, David D Y; Huang, Xiaohua; Zhou, Qing</p> <p>2016-07-01</p> <p>The wide application of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have led to their diffusion and accumulation in the environment. The activation of endocytosis is the primary response of plant cells to REEs. Calmodulin (CaM), as an important substance in calcium (Ca) signaling systems, regulating almost all of the physiological activities in plants, such as cellular metabolism, cell growth and division. However, the response of CaM to endocytosis activated by REEs remains unknown. By using immunofluorescence labeling and a confocal laser scanning microscope, we found that trivalent lanthanum [La(III)], an REE ion, affected the expression of CaM in endocytosis. Using circular dichroism, X-ray photoelectron spectroscopy and computer simulations, we demonstrated that a low concentration of La(III) could interact with extracellular CaM by electrostatic attraction and was then bound to two Ca-binding sites of CaM, making the molecular structure more compact and orderly, whereas a high concentration of La(III) could be coordinated with cytoplasmic CaM or bound to other Ca-binding sites, making the molecular structure more loose and disorderly. Our results provide a reference for revealing the action mechanisms of REEs in plant cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4730208','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4730208"><span>Innovative Application of Mechanical Activation for Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Recovering: Process Optimization and Mechanism Exploration</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tan, Quanyin; Deng, Chao; Li, Jinhui</p> <p>2016-01-01</p> <p>With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency. PMID:26819083</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21839555','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21839555"><span>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> tracing the soil erosion processes on slope surface under natural rainfall.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhu, Mingyong; Tan, Shuduan; Dang, Haishan; Zhang, Quanfa</p> <p>2011-12-01</p> <p>A field experiment using rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) as tracers was conducted to investigate soil erosion processes on slope surfaces during rainfall events. A plot of 10m×2m×0.16m with a gradient of 20° (36.4%) was established and the plot was divided into two layers and four segments. Various REE tracers were applied to the different layers and segments to determine sediment dynamics under natural rainfall. Results indicated that sheet erosion accounted for more than 90% of total erosion when the rainfall amount and density was not large enough to generate concentrated flows. Sediment source changed in different sections on the slope surface, and the primary sediment source area tended to move upslope as erosion progressed. In rill erosion, sediment discharge mainly originated from the toe-slope and moved upwards as erosion intensified. The results obtained from this study suggest that multi-REE tracer technique is valuable in understanding the erosion processes and determining sediment sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27670426','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27670426"><span>Using rare <span class="hlt">earth</span> <span class="hlt">elements</span> to constrain particulate organic carbon flux in the East China Sea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hung, Chin-Chang; Chen, Ya-Feng; Hsu, Shih-Chieh; Wang, Kui; Chen, Jian Feng; Burdige, David J</p> <p>2016-09-27</p> <p>Fluxes of particulate organic carbon (POC) in the East China Sea (ECS) have been reported to decrease from the inner continental shelf towards the outer continental shelf. Recent research has shown that POC fluxes in the ECS may be overestimated due to active sediment resuspension. To better characterize the effect of sediment resuspension on particle fluxes in the ECS, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and organic carbon (OC) were used in separate two-member mixing models to evaluate trap-collected POC fluxes. The ratio of resuspended particles from sediments to total trap-collected particles in the ECS ranged from 82-94% using the OC mixing model, and 30-80% using the REEs mixing model, respectively. These results suggest that REEs may be better proxies for sediment resuspension than OC in high turbidity marginal seas because REEs do not appear to undergo degradation during particle sinking as compared to organic carbon. Our results suggest that REEs can be used as tracers to provide quantitative estimates of POC fluxes in marginal seas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CryRp..61...55S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CryRp..61...55S"><span>Ionic conductivity of binary fluorides of potassium and rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sorokin, N. I.</p> <p>2016-01-01</p> <p>The ionic conductivity s of KYF4 and K2 RF5 single crystals ( R = Gd, Ho, Er) and KNdF4 and K2 RF5 ceramic samples ( R = Dy, Er) has been studied in the temperature range of 340-500°C. A comparative analysis of the σ values for these objects has been performed. Binary fluorides of potassium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> were synthesized by the hydrothermal method (temperature 480°C, pressure 100-150 MPa) in the R 2O3-KF-H2O systems. The σ values of tetraf luorides are 3 × 10-5 S/cm (KYF4 single crystal) and 3 × 10-6 S/cm (KNdF4 ceramics) at 435°C. A K2ErF5 single crystal with σ = 1.2 × 10-4 S/cm at 435°C has the maximum value of ionic conductivity among pentafluorides. The anisotropy of ionic transport was found in K2HoF5 single crystals, σ∥ c /σ⊥ c = 2.5, where σ∥ c and σ⊥ c are, respectively, the conductivities along the crystallographic c axis and in the perpendicular direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...619961T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...619961T"><span>Innovative Application of Mechanical Activation for Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Recovering: Process Optimization and Mechanism Exploration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tan, Quanyin; Deng, Chao; Li, Jinhui</p> <p>2016-01-01</p> <p>With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1265582','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1265582"><span>Selective Extraction of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from Permanent Magnet Scraps with Membrane Solvent Extraction</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, Daejin; Powell, Lawrence E.; Delmau, Lætitia H.; Peterson, Eric S.; Herchenroeder, Jim; Bhave, Ramesh R.</p> <p>2015-06-24</p> <p>In this paper, the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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. Finally, 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AIPC.1394...90S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AIPC.1394...90S"><span>Oxidation Resistance of Fe80Cr20 Alloys Treated by Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Ion Implantation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sebayang, Darwin; Khaerudini, Deni S.; Saryanto, H.; Hasan, Sulaiman; Othman, M. A.; Untoro, Puji</p> <p>2011-10-01</p> <p>The oxidation behaviour of newly developed process of Fe80Cr20 alloy was studied as a function of temperature in the range 1173-1273 K for up to 100 h in flowing air, which corresponds to the Solid Oxide Fuel Cell (SOFC) environment operating conditions. The effects of rare <span class="hlt">earth</span> <span class="hlt">element</span> implantation and depth profile on the oxidation behaviour of specimens were analyzed based on oxide morphology and microstructure. Characterisation of the oxide phase products after oxidation was made by X-ray diffraction (XRD). The surface morphology of oxide scales was examined using the scanning electronic microscope (SEM) with energy-dispersive X-ray analysis (EDX). The rate constant of thermal oxidation was determined using Wagner method. Experimental results show that the specimens implanted with lanthanum have remarkably enhanced the oxidation resistance. The oxidation test indicates that the newly developed process of Fe80Cr20 implantation with lanthanum ions exhibit considerably greater improvement in the oxidation resistance compared to the specimens implanted with titanium. The newly developed process of Fe80Cr20 milled for 60h show better oxidation resistance compared to specimens milled for 40h.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1265582-selective-extraction-rare-earth-elements-from-permanent-magnet-scraps-membrane-solvent-extraction','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1265582-selective-extraction-rare-earth-elements-from-permanent-magnet-scraps-membrane-solvent-extraction"><span>Selective Extraction of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from Permanent Magnet Scraps with Membrane Solvent Extraction</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Kim, Daejin; Powell, Lawrence E.; Delmau, Lætitia H.; ...</p> <p>2015-06-24</p> <p>In this paper, the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 acidmore » 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. Finally, 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.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22471924','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22471924"><span>Ionic conductivity of binary fluorides of potassium and rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sorokin, N. I.</p> <p>2016-01-15</p> <p>The ionic conductivity s of KYF{sub 4} and K{sub 2}RF{sub 5} single crystals (R = Gd, Ho, Er) and KNdF{sub 4} and K{sub 2}RF{sub 5} ceramic samples (R = Dy, Er) has been studied in the temperature range of 340–500°C. A comparative analysis of the σ values for these objects has been performed. Binary fluorides of potassium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> were synthesized by the hydrothermal method (temperature 480°C, pressure 100–150 MPa) in the R{sub 2}O{sub 3}–KF–H{sub 2}O systems. The σ values of tetraf luorides are 3 × 10{sup –5} S/cm (KYF{sub 4} single crystal) and 3 × 10{sup –6} S/cm (KNdF{sub 4} ceramics) at 435°C. A K{sub 2}ErF{sub 5} single crystal with σ = 1.2 × 10{sup –4} S/cm at 435°C has the maximum value of ionic conductivity among pentafluorides. The anisotropy of ionic transport was found in K{sub 2}HoF{sub 5} single crystals, σ{sub ∥c}/σ{sub ⊥c} = 2.5, where σ{sub ∥c} and σ{sub ⊥c} are, respectively, the conductivities along the crystallographic c axis and in the perpendicular direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5339825','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5339825"><span>Unusual seeding mechanism for enhanced performance in solid-phase magnetic extraction of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Polido Legaria, Elizabeth; Rocha, Joao; Tai, Cheuk-Wai; Kessler, Vadim G.; Seisenbaeva, Gulaim A.</p> <p>2017-01-01</p> <p>Due to the increasing demand of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE or RE), new and more efficient techniques for their extraction are necessary, suitable for both mining and recycling processes. Current techniques such as solvent extraction or solid adsorbents entail drawbacks such as using big volumes of harmful solvents or limited capacity. Hybrid nanoadsorbents based on SiO2 and highly stable γ-Fe2O3-SiO2 nanoparticles, proved recently to be very attractive for adsorption of REE, yet not being the absolute key to solve the problem. In the present work, we introduce a highly appealing new approach in which the nanoparticles, rather than behaving as adsorbent materials, perform as inducers of crystallization for the REE in the form of hydroxides, allowing their facile and practically total removal from solution. This induced crystallization is achieved by tuning the pH, offering an uptake efficiency more than 20 times higher than previously reported (up to 900 mg RE3+/g vs. 40 mg RE3+/g). The obtained phases were characterized by SEM-EDS, TEM, STEM and EFTEM and 13C and 29Si solid state NMR. Magnetic studies showed that the materials possessed enough magnetic properties to be easily removed by a magnet, opening ways for an efficient and industrially applicable separation technique. PMID:28266566</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24032646','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24032646"><span>Recycling rare <span class="hlt">earth</span> <span class="hlt">elements</span> from industrial wastewater with flowerlike nano-Mg(OH)(2).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Chaoran; Zhuang, Zanyong; Huang, Feng; Wu, Zhicheng; Hong, Yangping; Lin, Zhang</p> <p>2013-10-09</p> <p>Treatment of wastewater containing low-concentration yet highly-expensive rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) is one of the vital issues in the REEs separation and refining industry. In this work, the interaction and related mechanism between self-supported flowerlike nano-Mg(OH)2 and low-concentration REEs wastewater were investigated. More than 99% REEs were successfully taken up by nano-Mg(OH)2. Further analysis revealed that the REEs could be collected on the surface of Mg(OH)2 as metal hydroxide nanoparticles (<5 nm). An ion-exchange model was proposed as a critical factor for both guaranteeing the reaction speed and maintaining the self-supported structure of the materials. In addition, a method was developed to further separate the immobilized REEs and the residual magnesium hydroxide by varying the solution pH. In a pilot-scale experiment, the REEs from practical wastewater were immobilized effectively at a high flow rate. We anticipate this work can provide a good example for the recycling of valuable REEs in practical industrial applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010MMTA...41.1973N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010MMTA...41.1973N"><span>Effect of Ca and Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> on Impression Creep Properties of AZ91 Magnesium Alloy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nami, B.; Razavi, H.; Mirdamadi, S.; Shabestari, S. G.; Miresmaeili, S. M.</p> <p>2010-08-01</p> <p>Creep properties of AZ91 magnesium alloy and AZRC91 (AZ91 + 1 wt pct RE + 1.2 wt pct Ca) alloy were investigated using the impression creep method. It was shown that the creep properties of AZ91 alloy are significantly improved by adding Ca and rare <span class="hlt">earth</span> (RE) <span class="hlt">elements</span>. The improvement in creep resistance is mainly attributed to the reduction in the amount and continuity of eutectic β(Mg17Al12) phase as well as the formation of new Al11RE3 and Al2Ca intermetallic compounds at interdendritic regions. It was found that the stress exponent of minimum creep rate, n, varies between 5.69 and 6 for AZ91 alloy and varies between 5.81 and 6.46 for AZRC91 alloy. Activation energies of 120.9 ± 8.9 kJ/mol and 100.6 ± 7.1 kJ/mol were obtained for AZ91 and AZRC91 alloys, respectively. It was shown that the lattice and pipe-diffusion-controlled dislocation climb are the dominant creep mechanisms for AZ91 and AZRC91 alloys, respectively. The constitutive equations, correlating the minimum creep rate with temperature and stress, were also developed for both alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatSR...743740P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatSR...743740P"><span>Unusual seeding mechanism for enhanced performance in solid-phase magnetic extraction of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Polido Legaria, Elizabeth; Rocha, Joao; Tai, Cheuk-Wai; Kessler, Vadim G.; Seisenbaeva, Gulaim A.</p> <p>2017-03-01</p> <p>Due to the increasing demand of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE or RE), new and more efficient techniques for their extraction are necessary, suitable for both mining and recycling processes. Current techniques such as solvent extraction or solid adsorbents entail drawbacks such as using big volumes of harmful solvents or limited capacity. Hybrid nanoadsorbents based on SiO2 and highly stable γ-Fe2O3-SiO2 nanoparticles, proved recently to be very attractive for adsorption of REE, yet not being the absolute key to solve the problem. In the present work, we introduce a highly appealing new approach in which the nanoparticles, rather than behaving as adsorbent materials, perform as inducers of crystallization for the REE in the form of hydroxides, allowing their facile and practically total removal from solution. This induced crystallization is achieved by tuning the pH, offering an uptake efficiency more than 20 times higher than previously reported (up to 900 mg RE3+/g vs. 40 mg RE3+/g). The obtained phases were characterized by SEM-EDS, TEM, STEM and EFTEM and 13C and 29Si solid state NMR. Magnetic studies showed that the materials possessed enough magnetic properties to be easily removed by a magnet, opening ways for an efficient and industrially applicable separation technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70176350','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70176350"><span>Marine phosphorites as potential resources for heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> and yttrium</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hein, James; Koschinsky, Andrea; Mikesell, Mariah; Mizell, Kira; Glenn, Craig R.; Wood, Ray</p> <p>2016-01-01</p> <p>Marine phosphorites are known to concentrate rare <span class="hlt">earth</span> <span class="hlt">elements</span> and yttrium (REY) during early diagenetic formation. Much of the REY data available are decades old and incomplete, and there has not been a systematic study of REY distributions in marine phosphorite deposits that formed over a range of oceanic environments. Consequently, we initiated this study to determine if marine phosphorite deposits found in the global ocean host REY concentrations of high enough grade to be of economic interest. This paper addresses continental-margin (CM) and open-ocean seamount phosphorites. All 75 samples analyzed are composed predominantly of carbonate fluorapatite and minor detrital and authigenic minerals. CM phosphorites have low total REY contents (mean 161 ppm) and high heavy REY (HREY) complements (mean 49%), while seamount phosphorites have 4–6 times higher individual REY contents (except for Ce, which is subequal; mean ΣREY 727 ppm), and very high HREY complements (mean 60%). The predominant causes of higher concentrations and larger HREY complements in seamount phosphorites compared to CM phosphorites are age, changes in seawater REY concentrations over time, water depth of formation, changes in pH and complexing ligands, and differences in organic carbon content in the depositional environments. Potential ore deposits with high HREY complements, like the marine phosphorites analyzed here, could help supply the HREY needed for high-tech and green-tech applications without creating an oversupply of the LREY.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24135922','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24135922"><span>State of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in different environmental components in mining areas of China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liang, Tao; Li, Kexin; Wang, Lingqing</p> <p>2014-03-01</p> <p>China has relatively abundant rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) reserves and will continue to be one of the major producers of REEs for the world market in the foreseeable future. However, due to the large scale of mining and refining activities, large amounts of REEs have been released to the surrounding environment and caused harmful effects on local residents. This paper summarizes the data about the contents and translocation of REEs in soils, waters, atmosphere, and plants in REE mining areas of China and discusses the characteristics of their forms, distribution, fractionation, and influencing factors. Obviously high concentrations of REEs with active and bioavailable forms are observed in all environmental media. The mobility and bioavailability of REEs are enhanced. The distribution patterns of REEs in soils and water bodies are all in line with their parent rocks. Significant fractionation phenomenon among individual members of REEs was found in soil-plant systems. However, limited knowledge was available for REEs in atmosphere. More studies focusing on the behavior of REEs in ambient air of REE mining areas in China are highly suggested. In addition, systematic study on the translocation and circulation of REEs in various media in REEs mining areas and their health risk assessment should be carried out. Standard analytical methods of REEs in environments need to be established, and more specific guideline values of REEs in foods should also be developed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26378553','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26378553"><span>Remediation of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Pollutants by Sorption Process Using Organic Natural Sorbents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Butnariu, Monica; Negrea, Petru; Lupa, Lavinia; Ciopec, Mihaela; Negrea, Adina; Pentea, Marius; Sarac, Ionut; Samfira, Ionel</p> <p>2015-09-10</p> <p>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 <span class="hlt">earth</span> <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25000508','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25000508"><span>Examination of rare <span class="hlt">earth</span> <span class="hlt">element</span> concentration patterns in freshwater fish tissues.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mayfield, David B; Fairbrother, Anne</p> <p>2015-02-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 (ΣREE) 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014731','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014731"><span>Determination of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in geological materials by inductively coupled plasma mass spectrometry</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lichte, F.E.; Meier, A.L.; Crock, J.G.</p> <p>1987-01-01</p> <p>A method of analysis of geological materials for the determination of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JMEP...23.4251L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JMEP...23.4251L"><span>Effect of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> on Isothermal Transformation Kinetics in Si-Mn-Mo Bainite Steels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liang, Yilong; Yi, Yanliang; Long, Shaolei; Tan, Qibing</p> <p>2014-12-01</p> <p>Isothermal heat treatments to Si-Mn-Mo steel specimens were performed, and time-temperature-transformation curves (C-curves) were plotted by DIL805A/D differential dilatometer. The effect of rare <span class="hlt">earth</span> (RE) <span class="hlt">elements</span> on bainite transformation kinetics was systematically studied by adopting the empirical electron theory of solids and molecules, Johnson-Mehl-Avrami equation calculation, dilatometry, and metallography. Experimental results show that the addition of RE in Si-Mn-Mo bainite steels leads to the C-curves moving to bottom right and prolongs incubation period of bainite transformation. Moreover, RE addition increases the values of phase structure factors ( n A, F {C/D}) and activation energy of bainite transformation, inhibits the formation of granular bainite, and refines microstructures of bainitic ferrite and substructures. During the bainite transformation process, bainite transformation is delayed due to the drag effect, which is induced by the segregation of RE at the ferrite interphase and the retardation of Fe-C-RE (segregation units) on carbon diffusion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4586675','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4586675"><span>Remediation of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Pollutants by Sorption Process Using Organic Natural Sorbents</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Butnariu, Monica; Negrea, Petru; Lupa, Lavinia; Ciopec, Mihaela; Negrea, Adina; Pentea, Marius; Sarac, Ionut; Samfira, Ionel</p> <p>2015-01-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">element</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JaJAP..50iNE01H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JaJAP..50iNE01H"><span>Theoretical Study on Interactions between Oxygen Vacancy and Doped Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span> in Barium Titanate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Honda, Atsushi; Higai, Shin'ichi; Motoyoshi, Yasuhiro; Wada, Nobuyuki; Takagi, Hiroshi</p> <p>2011-09-01</p> <p>We performed first-principles theoretical calculations to examine the interactions between oxygen vacancy (VO) and rare-<span class="hlt">earth</span> (RE) <span class="hlt">elements</span> in barium titanate (BaTiO3), in order to clarify the mechanism of VO trapping by RE dopants, which affects the insulating reliability of BaTiO3-based multilayer ceramic capacitors (MLCC). It was found that VO is stabilized at the first and second nearest O sites of RE at Ba site (REBa), and at the second nearest O site of RE at Ti site (RETi). The structural relaxations on bond lengths of REBa-O and RETi-O in BaTiO3, which are brought about by the existence of VO at the above sites, decrease the total energy, and thus VO is stabilized. Furthermore, we revealed that the stability of VO increases with decreasing solution stability of RE dopants in BaTiO3. Accordingly, we concluded that RE dopants with higher solution energy in BaTiO3 efficiently trap VO, and thus the insulation reliability of MLCC is improved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OSJ....51..305K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OSJ....51..305K"><span>Rare <span class="hlt">earth</span> <span class="hlt">element</span> fingerprints in Korean coastal bay sediments: Association with provenance discrimination</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kang, Jeongwon; Woo, Han Jun; Jang, Seok; Jeong, Kap-Sik; Jung, Hoi-Soo; Hwang, Ha Gi; Lee, Jun-Ho; Cho, Jin Hyung</p> <p>2016-09-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs: La-Lu) in surface sediments collected from the mouth and middle tidal flats of Gomso Bay, South Korea, in August 2011 and May 2012 were analyzed to investigate the fine-grained sediment provenance. The upper continental crust (UCC)-normalized light REEs (LREEs: La to Nd) were more enriched than the middle REEs (MREEs: Sm to Dy) and heavy REEs (HREEs: Ho to Lu), resulting in large (La/Yb)UCC (1.9 ± 0.4) to (Gd/Yb)UCC (1.4 ± 0.2) ratios. The monthly (La/Yb)UCC values differed between the mouth and middle tidal flats due to deposition of fine-grained sediments that originated from distant rivers (the Geum and Yeongsan) and the Jujin Stream, located on the southern shore of the inner bay. We observed relative reductions in the (La/Yb)UCC value and REE content in the sediments from the mouth of the bay compared with those from Jujin Stream sediments. Confined to the middle tidal flat around the KH Line of Jujin Stream, the sediments, most enriched in LREEs but depleted in Eu, were distributed in August as strong Jujin Stream runs. Here, we suggest that an increase in LREE/HREE and decrease in MREE/LREE ratios can be used as a proxy to identify the Jujin Stream provenance in mixed riverine sediments and to trace Jujin Stream sediments within the Gomso Bay tidal flat, especially in the summer rainy season.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26107531','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26107531"><span>Selective Extraction of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from Permanent Magnet Scraps with Membrane Solvent Extraction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R</p> <p>2015-08-18</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70184351','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70184351"><span>The behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in naturally and anthropogenically acidified waters</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wood, Scott A.; Gammons, Christopher H.; Parker, Stephen R.</p> <p>2006-01-01</p> <p>In this paper, the behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in a watershed impacted by acid-mine drainage (Fisher Creek, Montana) is compared to that in a volcanically acidified watershed (Rio Agrio and Lake Caviahue, Argentina). The REE behave conservatively in acidic waters with pH values less than approximately 5.5. However, above pH 5.5, REE concentrations are controlled by adsorption onto or co-precipitation with a variety of Fe or Al oxyhydroxides. The heavy REE partition to a greater extent into the solid phase than the light REE as pH rises above 6. Concentrations of REE exhibit diel (24-h) cycling in waters that were initially acidic, but have become neutralized downstream. In Fisher Creek, at the most downstream sampling station investigated (pH 6.8), concentrations of dissolved REE were 190–840% higher in the early morning versus the late afternoon. This cycling can be related to temperature-dependent, cyclic adsorption–desorption of REE onto hydrous ferric or aluminum oxide or both. Similar but gentler diel cycling of the REE was found at Rio Agrio. The existence of such cycling has important ramifications for the study of REE in natural waters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012626','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012626"><span>Rare <span class="hlt">earth</span> <span class="hlt">element</span> distribution in some hydrothermal minerals: evidence for crystallographic control</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morgan, J.W.; Wandless, G.A.</p> <p>1980-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26819083','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26819083"><span>Innovative Application of Mechanical Activation for Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Recovering: Process Optimization and Mechanism Exploration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tan, Quanyin; Deng, Chao; Li, Jinhui</p> <p>2016-01-28</p> <p>With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996SuScT...9.1015M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996SuScT...9.1015M"><span>TOPICAL REVIEW: Melt-processed light rare <span class="hlt">earth</span> <span class="hlt">element</span> - Ba - Cu - O</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murakami, M.; Sakai, N.; Higuchi, T.; Yoo, S. I.</p> <p>1996-12-01</p> <p>Unlike Y123 which forms only a stoichiometric compound, the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREs: La, Nd, Sm, Eu, Gd) form a solid solution 0953-2048/9/12/001/img1. The presence of such solid solution caused a depression in the superconducting transition temperatures 0953-2048/9/12/001/img2, particularly for La123, Nd123 and Sm123 when they are melt processed in air. Recently, we have found that the 0953-2048/9/12/001/img3 of these LRE123 superconductors can greatly be enhanced when they are melt processed in a reduced oxygen atmosphere. Furthermore, 0953-2048/9/12/001/img4 values of these superconductors were larger than that of a good quality Y123 superconductor in high magnetic fields at 77 K. In this article, on the basis of our study over the last several years, the melt processes for LRE - Ba - Cu - O are described, the microstructural and superconducting properties of the superconductors are reviewed and the flux pinning mechanism is also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770064910&hterms=single+parent&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsingle%2Bparent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770064910&hterms=single+parent&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsingle%2Bparent"><span>Composition and evolution of the eucrite parent body - Evidence from rare <span class="hlt">earth</span> <span class="hlt">elements</span>. [extraterrestrial basaltic melts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Consolmagno, G. J.; Drake, M. J.</p> <p>1977-01-01</p> <p>Quantitative modeling of the evolution of rare <span class="hlt">earth</span> <span class="hlt">element</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7302586','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7302586"><span>Cerium redox cycles and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Sargasso Sea</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sholkovitz, E.R.; Schneider, D.L. )</p> <p>1991-10-01</p> <p>Two profiles of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5037389','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5037389"><span>Using rare <span class="hlt">earth</span> <span class="hlt">elements</span> to constrain particulate organic carbon flux in the East China Sea</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hung, Chin-Chang; Chen, Ya-Feng; Hsu, Shih-Chieh; Wang, Kui; Chen, Jian Feng; Burdige, David J.</p> <p>2016-01-01</p> <p>Fluxes of particulate organic carbon (POC) in the East China Sea (ECS) have been reported to decrease from the inner continental shelf towards the outer continental shelf. Recent research has shown that POC fluxes in the ECS may be overestimated due to active sediment resuspension. To better characterize the effect of sediment resuspension on particle fluxes in the ECS, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and organic carbon (OC) were used in separate two-member mixing models to evaluate trap-collected POC fluxes. The ratio of resuspended particles from sediments to total trap-collected particles in the ECS ranged from 82–94% using the OC mixing model, and 30–80% using the REEs mixing model, respectively. These results suggest that REEs may be better proxies for sediment resuspension than OC in high turbidity marginal seas because REEs do not appear to undergo degradation during particle sinking as compared to organic carbon. Our results suggest that REEs can be used as tracers to provide quantitative estimates of POC fluxes in marginal seas. PMID:27670426</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24483647','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24483647"><span>New fission fragment distributions and r-process origin of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Goriely, S; Sida, J-L; Lemaître, J-F; Panebianco, S; Dubray, N; Hilaire, S; Bauswein, A; Janka, H-T</p> <p>2013-12-13</p> <p>Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process <span class="hlt">elements</span> 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-<span class="hlt">earth</span> 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.</p> </li> <li> <p><a target="_blank" o