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Sample records for earth element geochemistry

  1. 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.

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

    DOE PAGESBeta

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

    SciTech Connect

    Shokovitz, E.R. )

    1993-05-01

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

  4. Rare earth element geochemistry and petrogenesis of miles (IIE) silicate inclusions

    NASA Astrophysics Data System (ADS)

    Hsu, Weibiao

    2003-12-01

    An ion probe study of rare earth element (REE) geochemistry of silicate inclusions in the Miles IIE iron meteorite was carried out. Individual mineral phases among inclusions have distinct REE patterns and abundances. Most silicate grains have homogeneous REE abundances but show considerable intergrain variations between inclusions. A few pyroxene grains display normal igneous REE zoning. Phosphates (whitlockite and apatite) are highly enriched in REEs (50 to 2000 × CI) with a relatively light rare earth element (LREE)-enriched REE pattern. They usually occurred near the interfaces between inclusions and Fe host. In Miles, albitic glasses exhibit two distinctive REE patterns: a highly fractionated LREE-enriched (CI normalized La/Sm ˜15) pattern with a large positive Eu anomaly and a relatively heavy rare earth element (HREE)-enriched pattern (CI-normalized Lu/Gd ˜4) with a positive Eu anomaly and a negative Yb anomaly. The glass is generally depleted in REEs relative to CI chondrites. The bulk REE abundances for each inclusion, calculated from modal abundances, vary widely, from relatively depleted in REEs (0.1 to 3 × CI) with a fractionated HREE-enriched pattern to highly enriched in REEs (10 to 100 × CI) with a relatively LREE-enriched pattern. The estimated whole rock REE abundances for Miles are at ˜ 10 × CI with a relatively LREE-enriched pattern. This implies that Miles silicates could represent the product of a low degree (˜10%) partial melting of a chondritic source. Phenocrysts of pyroxene in pyroxene-glassy inclusions were not in equilibrium with coexisting albitic glass and they could have crystallized from a parental melt with REEs of ˜ 10 × CI. Albitic glass appears to have formed by remelting of preexisting feldspar + pyroxene + tridymite assemblage. Yb anomaly played an important role in differentiation processes of Miles silicate inclusions; however, its origin remains unsolved. The REE data from this study suggest that Miles, like

  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. Distribution and Geochemistry of Rare-Earth Elements in Rivers of Southern and Eastern Primorye (Far East of Russia)

    NASA Astrophysics Data System (ADS)

    Chudaev, O. V.; Bragin, I. V.; A, Kharitonova N.; Chelnokov, G. A.

    2016-03-01

    The distribution and geochemistry of rare earth elements (REE) in anthropogenic, technogenic and natural surface waters of southern and eastern Primorye, Far East of Russia, are presented in this study. The obtained results indicated that most of REE (up to 70%) were transported as suspended matter, ratio between dissolved and suspended forms varing from the source to the mouth of rivers. It is shown that all REE (except Ce) in the source of the rivers are predominantly presented in dissolved form, however, the content of light and heavy REE is different. Short-term enrichment of light rare earth elements (LREE) caused by REE-rich runoff from waste dumps and mining is neutralized by the increase in river flow rate. Rivers in urban areas are characterized by high content of LREE in dissolved form and very low in suspended one.

  9. 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.

  10. 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.

  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. PMID:26247412

  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 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.

  15. 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

  16. Rare earth element geochemistry in cold-seep pore waters of Hydrate Ridge, northeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Himmler, Tobias; Haley, Brian A.; Torres, Marta E.; Klinkhammer, Gary P.; Bohrmann, Gerhard; Peckmann, Jörn

    2013-07-01

    The concentrations of rare earth elements (REEs), sulphate, hydrogen sulphide, total alkalinity, calcium, magnesium and phosphate were measured in shallow (<12 cm below seafloor) pore waters from cold-seep sediments on the northern and southern summits of Hydrate Ridge, offshore Oregon. Downward-decreasing sulphate and coevally increasing sulphide concentrations reveal sulphate reduction as dominant early diagenetic process from ~2 cm depth downwards. A strong increase of total dissolved REE (∑REE) concentrations is evident immediately below the sediment-water interface, which can be related to early diagenetic release of REEs into pore water resulting from the re-mineralization of particulate organic matter. The highest pore water ∑REE concentrations were measured close to the sediment-water interface at ~2 cm depth. Distinct shale-normalized REE patterns point to particulate organic matter and iron oxides as main REE sources in the upper ~2-cm depth interval. In general, the pore waters have shale-normalized patterns reflecting heavy REE (HREE) enrichment, which suggests preferential complexation of HREEs with carbonate ions. Below ~2 cm depth, a downward decrease in ∑REE correlates with a decrease in pore water calcium concentrations. At this depth, the anaerobic oxidation of methane (AOM) coupled to sulphate reduction increases carbonate alkalinity through the production of bicarbonate, which results in the precipitation of carbonate minerals. It seems therefore likely that the REEs and calcium are consumed during vast AOM-induced precipitation of carbonate in shallow Hydrate Ridge sediments. The analysis of pore waters from Hydrate Ridge shed new light on early diagenetic processes at cold seeps, corroborating the great potential of REEs to identify geochemical processes and to constrain environmental conditions.

  17. The geochemistry of rare earth elements in groundwater from the Carnmenellis area, southwest England

    SciTech Connect

    Smedley, P.L. )

    1991-10-01

    Shallow groundwater samples from the Carnmenellis area of southwest England collected from wells, boreholes, springs, adits and stream baseflow represent recently recharged waters of low salinity. Their major ion concentrations closely reflect the lithology of their host rocks which comprise the Carnmenellis granite and Devonian metasediments (and metabasite) of greenschist grade. Groundwaters from the granite are predominantly Na-Cl or Na-Ca-Cl type while those from the metasediment are Na-Ca-Mg-Cl-HCO{sub 3} waters with a larger range of compositions. The major ion compositions are predominantly a function of water-rock interaction processes and the larger range of metasediment-water compositions probably reflects the greater lithological variation. Rare earth element (REE) concentrations of 0.45 {mu}m-filtered groundwater samples have been determined by inductively coupled plasma mass spectrometry (ICP-MS). A large range of concentrations exists and many are below detection limits but levels reach up to 229 {mu}g/1 (1.6 {mu}m) total REEs. The REEs are strongly controlled by pH with higher levels in groundwaters of pH < 6. In the granite, the REEs are probably derived mainly from the accessory minerals monazite and apatite as well as the high-REE framework minerals biotite and muscovite. The source of REEs in groundwater from the metasediments is more uncertain but probably includes clay minerals, chlorite, and carbonate. The observed REE compositions of granite- and metasediment-derived groundwaters from the Carnmenellis area are so distinctive that the REEs in general and Ce in particular might be useful as future tracers in studies of water-rock interaction and groundwater provenance.

  18. 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. PMID:12598196

  19. 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

  20. Mineralogy and geochemistry of trace and Rare Earth Element from the Manaila massive sulphide deposit (Eastern Carpathians, Romania)

    NASA Astrophysics Data System (ADS)

    Moldoveanu, S.; Iancu, O. G.; Kasper, H. U.

    2012-04-01

    Keywords: Eastern Carpathians, Mănăila deposit, REE, trace elements, pyrite The present paper deal with the mineralogy and trace elements geochemistry of sulphide deposits from Mănăila mine field located in NE area of Eastern Carpathians Mountains (Romania). The mineralization occurs within metamorphic rocks of Tulgheş terrane, part of Crystalline-Mezozoic zone of the Eastern Carpathians. The metamorphic rocks in Mănăila area consist of felsic metavolcanics rocks with quartzites and quartz-feldspathic rocks as prevailing types. The P-T metamorphic conditions are typical of greenschis facies with biotite and garnet (Mn-Grt) in mineral assemblage. The mineralogical study was performed using reflected light microscope and Scanning Electron Microscopy (SEM) methods. Thus, the both methods show that the main sulphides minerals are represented by pyrite and chalcopyrite, being followed by sphalerite, galena and little amount of Cu sulphosalts (tetrahedrite and bournonite) and also by gangue minerals (quartz and carbonates). Pyrite occurs as large euhedral to subhedral grains in quartz and small rounded inclusion in chalcopyrite. The trace elements analysis was achieved on whole-rock samples and involved the determination of REE, LIL (Rb, Ba, Sr) and HFS (Y, Zr, Hf, U, Th, Nb, Ta) by ICP-MS method. The concentration of LIL and HFS trace elements in mineralized rocks decrease as follows: Ba > Bi > As > Sb > Co > Ga > Ni > Cd. Even if the barium contents in Mănăila ore is high, baritina (BaSO4) was not identified throught the mineralogical analyses carried out so far. The total rare earth element content (REE) of the samples from Mănăila range from 26.84 to 246.46 ppm. Chondrite - normalized REE patterns of the mineralized rocks show that the LREE are enriched in relation to the HREE. Also a positive Ce anomalies and negative Eu anomalies are present. Y/Ho and Zr/Hf ratios are close to the chondritic ratios indicating Charge-and-Radius-Controlled (CHARAC

  1. Rare earth element and stable isotope (O, S) geochemistry of barite from the Bijgan deposit, Markazi Province, Iran

    NASA Astrophysics Data System (ADS)

    Ehya, Farhad

    2012-01-01

    The Bijgan barite deposit, which is located northeast of Delijan in Markazi Province of Iran, occurs as a small lenticular body at the uppermost part of an Eocene volcano-sedimentary rock unit. The presence of fossiliferous and carbonaceous strata suggests that the host rocks were deposited in a quiet marine sedimentary environment. Barite, calcite, iron oxides and carbonaceous clay materials are found as massive patches as well as thin layers in the deposit. Barite is marked by very low concentrations of Sr (1-2%) and total amounts of rare earth elements (REEs) (6.25-17.39 ppm). Chondrite-normalized REE patterns of barite indicate a fractionation of light REEs (LREEs) from La to Sm, similar to those for barite of different origins from elsewhere. The LaCN/LuCN ratios and chondrite-normalized REE patterns reveal that barite in the Bijgan deposit is enriched in LREE relative to heavy rare earth elements (HREEs). The similarity between the Ce/La ratios in the barite samples and those found in deep-sea barite supports a marine origin for barite. Lanthanum and Gd exhibit positive anomalies, which are common features of marine chemical sediments. Cerium shows a negative anomaly in most samples that was inherited from the negative Ce anomaly of hydrothermal fluid that mixed with seawater at the time of barite precipitation. The δ18O values of barites show a narrow range of 9.1-11.4‰, which is close to or slightly lower than that of contemporaneous seawater at the end of the Eocene. This suggests a contribution of oxygen from seawater in the barite-forming solution. The δ34S values of barites (9.5-15.3‰) are lower than that of contemporaneous seawater, which suggests a contribution of magmatic sulfur to the ore-forming solution. The oxygen and sulfur isotope ratios indicate that submarine hydrothermal vent fluids are a good analog for solutions that precipitated barite, due to similarities in the isotopic composition of the sulfates. The available data including

  2. 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

  3. 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.

  4. 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

  5. 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

  6. Early depositional history of metalliferous sediments in the Atlantis II Deep of the Red Sea: Evidence from rare earth element geochemistry

    NASA Astrophysics Data System (ADS)

    Laurila, Tea E.; Hannington, Mark D.; Petersen, Sven; Garbe-Schönberg, Dieter

    2014-02-01

    The Atlantis II Deep is a brine-filled depression on the slowly spreading Red Sea rift axis. It is by far the largest deposit of hydrothermally precipitated metals on the present ocean floor and the only known modern deposit that is analogous to laminated Fe-rich chemical sediments, such as banded iron formation (BIF). The brine pool at the bottom of the Atlantis II Deep creates an environment where most of the hydrothermally sourced elements can be dispersed and deposited over an area of ˜60 km2. We analyzed the rare earth element concentrations in 100 small-volume samples from 9 cores in different parts of the Atlantis II Deep to better understand the origins of different types of metalliferous sediments (detrital, proximal hydrothermal and distal hydrothermal). Our results agree with earlier studies based on larger bulk samples that show the composition of the major depositional units is related to major changes in the location and intensity of hydrothermal activity and the amount of hydrothermal versus background sedimentation. In this paper, we address the origins of chemically distinct laminae (down to sub-millimeter) that correspond to ˜annual deposition. REE patterns clearly reflect 3 different sources (e.g., detrital, scavenging, direct hydrothermal input). Detrital REE that are delivered to the Deep from outside account for most of the REE in the sediments of the Atlantis II Deep, similar to BIF, and are unaffected by fractionation due to hydrothermal processes during deposition and diagenesis. Fe- and Mn-(oxy)hydroxides that form at the anoxic-oxic boundary scavenge REE from the brine pool as they settle. The Fe-(oxy)hydroxides contain a larger proportion of REE from seawater than any other sediment-type and also scavenge REE from pore waters after deposition. In contrast, the Mn-(oxy)hydroxides dissolve before deposition and thus function as transporting agents between seawater and the brine. However, there is little evidence for direct seawater

  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. Global Oceanic Basalt Geochemistry From EarthChem Databases

    NASA Astrophysics Data System (ADS)

    Hofmann, A. W.; Sarbas, B.; Jochum, K. P.; Stracke, A.

    2004-12-01

    For the past 21 years, global trace element systematics in oceanic basalts have been systematically developed, using mass spectrometry, by the MPI geochemistry department in Mainz, starting with Ba-Rb-Cs, and continuing with K-U-Th, Nb-U-Th, Pb-Ce, Pr-Mo, Nb-Ta, Sn-REE, Sb-REE, and Y-Ho relations. These were complemented by other groups, contributing e.g. Sr-REE relationships and more refined Nb-Ta systematics. Goal of these investigations was to establish relative trace element compatibilities during mantle melting, the corresponding enrichment and depletion patterns in MORB, OIB, subduction-related volcanics and the continental crust, and the relationships to Bulk Silicate Earth abundances through comparisons with element abundances in meteorites and in the continental crust (see e.g. [1]). Most of these studies were initially based on extremely limited data sets, often fewer than 100 analyses, because routine analytical techniques such as XRF and INAA were inadequate, either in sensitivity or accuracy or both, for many of the elements of interest. The advent of ICPMS technology has increased the volume of available, useable data enormously. The most recent development of laser source ICPMS is accelerating the acquisition of comprehensive trace element data even more dramatically. Although the general quality of recent trace element analyses has improved significantly, there remain large differences in reliability between published data because of varying analytical uncertainties and sample alteration. Thus, quality assurance remains an enormous task. In any case, now and in the foreseeable future, it will be impossible to assess global geochemical data without the use of comprehensive databases. Such databases are now available under http://www.earthchem.org/, comprising http://beta.petdb.ciesin.columbia.edu/; http://georoc.mpch-mainz.gwdg.de/, and http://navdat.geo.ku.edu/ . Unfortunately, the use of such databases is not without pitfalls. Often, appropriate

  9. Geochemistry.

    ERIC Educational Resources Information Center

    Fyfe, William S.

    1979-01-01

    Techniques in geochemistry continue to improve in sensitivity and scope. The exciting areas of geochemistry still include the classical fields of the origin of the elements and objects in space, but environmental crisis problems are important as well. (Author/BB)

  10. Trace- and rare-earth-element geochemistry of the June 1993 natrocarbonatite lavas, Oldoinyo Lengai (Tanzania): Implications for the origin of carbonatite magmas

    NASA Astrophysics Data System (ADS)

    Simonetti, Antonio; Bell, Keith; Shrady, Catherine

    1997-01-01

    Major-, trace- and rare-earth-element data from ten natrocarbonatite lavas collected during the June 1993 extrusive activity define two distinct groups. Although both groups are characterized by low Nb and Zr contents, and low Th/U (~1.0); Ba/Sr>1.0; (La/Sm) N>40; high Ba, Mo, Sr, W contents; and LREE contents ~1000 to 2000×chondrite, one group has much higher Al 2O 3, Fe 2O 3, Nb, Pb, SiO 2, Zr and total REEs contents. These differences are attributed to the presence of silicate spheroids in natrocarbonatites that form within the latter group. Similarity in trace- and rare-earth-element-normalized patterns for both groups of natrocarbonatite lavas suggest either a common source or generation from a common parental melt. Models proposed for the origin of natrocarbonatites include immiscible separation from a peralkaline, silicate magma, or late-stage fractionation from a parent olivine sövite magma. Although natrocarbonatite melt formation may be controlled by either of these differentiation processes, certain trace-element ratios for the 1993 lavas, such as Ce/Pb (~9), and Th/Nb (~0.1) are similar to those estimated for primitive mantle, and their Sm/Nd ratios (~0.07) are quite different to the average value of 0.15 for most carbonatites world-wide. The similarity in element ratios in many of the older silicate lavas at Oldoinyo Lengai (e.g., Zr/Nb, La/Nb, Ba/Nb, Rb/Nb, and Ba/La) to those estimated for HIMU and EM I suggest that source characteristics can be reflected in such melts. Even if the natrocarbonatites are formed by liquid immiscibility, recent experiments have shown that partition coefficients for trace elements (e.g., Ba, Ce, Mo, Nb, Pb, Th, U) between conjugate carbonate and silicate melts approach unity with increasing temperature. Alternatively, the similarity in trace-element ratios between those for the silicate lavas from Oldoinyo Lengai and mantle components are simply fortuitous.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. Fluid inclusion, rare earth element geochemistry, and isotopic characteristics of the eastern ore zone of the Baiyangping polymetallic Ore district, northwestern Yunnan Province, China

    NASA Astrophysics Data System (ADS)

    Feng, Caixia; Bi, Xianwu; Liu, Shen; Hu, Ruizhong

    2014-05-01

    The Baiyangping Cu-Ag polymetallic ore district is located in the northern part of the Lanping-Simao foreland fold belt, which lies between the Jinshajiang-Ailaoshan and Lancangjiang faults in western Yunnan Province, China. The source of ore-forming fluids and materials within the eastern ore zone were investigated using fluid inclusion, rare earth element (REE), and isotopic (C, O, and S) analyses undertaken on sulfides, gangue minerals, wall rocks, and ores formed during the hydrothermal stage of mineralization. These analyses indicate: (1) The presence of five types of fluid inclusion, which contain various combinations of liquid (l) and vapor (v) phases at room temperature: (a) H2O (l), (b) H2O (l) + H2O (v), (c) H2O (v), (d) CmHn (v), and (e) H2O (l) + CO2 (l), sometimes with CO2 (v). These inclusions have salinities of 1.4-19.9 wt.% NaCl equivalents, with two modes at approximately 5-10 and 16-21 wt.% NaCl equivalent, and homogenization temperatures between 101 °C and 295 °C. Five components were identified in fluid inclusions using Raman microspectrometry: H2O, dolomite, calcite, CH4, and N2. (2) Calcite, dolomitized limestone, and dolomite contain total REE concentrations of 3.10-38.93 ppm, whereas wall rocks and ores contain REE concentrations of 1.21-196 ppm. Dolomitized limestone, dolomite, wall rock, and ore samples have similar chondrite-normalized REE patterns, with ores in the Huachangshan, Xiaquwu, and Dongzhiyan ore blocks having large negative δCe and δEu anomalies, which may be indicative of a change in redox conditions during fluid ascent, migration, and/or cooling. (3) δ34S values for sphalerite, galena, pyrite, and tetrahedrite sulfide samples range from -7.3‰ to 2.1‰, a wide range that indicates multiple sulfur sources. The basin contains numerous sources of S, and deriving S from a mixture of these sources could have yielded these near-zero values, either by mixing of S from different sources, or by changes in the geological

  17. Geochemistry: Hydrogen and oxygen in the deep Earth

    NASA Astrophysics Data System (ADS)

    Yagi, Takehiko

    2016-06-01

    The finding that an unusual iron oxide forms at extremely high pressures suggests that hydrogen and oxygen -- two elements that strongly influence Earth's evolution -- are generated in the mantle. See Letter p.241

  18. Development of a Rare Earth Element Paleoproxy

    NASA Astrophysics Data System (ADS)

    Haley, B. A.; Klinkhammer, G. P.; McManus, J.

    2002-12-01

    The rare earth elements (REEs) have demonstrated considerable potential as paleoproxies for changes in seawater chemistry. However, their utilization in paleoceanographic investigations has been mainly limited to neodymium isotopic analyses in metalliferous deposits and fossil apatite. The goal of being able to use the entire group of elements in foraminiferal shells has proven difficult. The problem with analysis of these elements in this matrix stems mainly from: (1) the ability to clean the shells of diagenetic aberrations and (2) the paucity of REE data in the environment where forams obtain their primary signature. We recently measured pore water profiles of REEs using an interfaced Ion Chromatograph (IC) and Inductively Coupled Plasma Mass Spectrometer (ICP-MS) in a depth transect off the Coast of California, and a profile from off the Peru-Chile margin. The pore water results are surprising and will alter our view of REE marine geochemistry. For example, they call into question the traditional method of calculating a "Ce-anomaly." The profiles also show dramatic changes in REE concentrations and patterns with depth, and demonstrate that the REE signature preserved in epifaunal benthic versus infaunal foram species and diagenetically added phases should be easily identifiable. Preliminary REE results from forams cleaned via a recently developed flow-through technique will be shown and compared to matching pore water data. We will conclude by outlining the potential of foraminiferal REE content for paleoceanography that ranges from water mass tracer to proxies for organic carbon flux and oxygen concentration.

  19. Tungsten geochemistry and implications for understanding the Earth's interior

    NASA Astrophysics Data System (ADS)

    Arevalo, Ricardo; McDonough, William F.

    2008-08-01

    The concentration of tungsten (W) in basaltic melts provides a window into the behavior of this element during core-mantle separation, crust formation, silicate differentiation, and potentially core-mantle interaction. We have analyzed an extensive suite of modern basalts ( n = 86) for their trace element chemistry via laser ablation ICP-MS, with barium (Ba), thorium (Th), uranium (U), and W concentrations typically determined to ≤ 5% (2 σ) uncertainty. We find that the partitioning behavior of U mirrors that of W during basalt genesis, whereas Ba and Th both behave more incompatibly. The W/U ratio of our complete sample suite (0.65 ± 0.45, 2 σ) is representative of the mean modern mantle, and is indistinguishable from that of mid-ocean ridge basalts (W/U MORB = 0.65 ± 0.41, n = 52), ocean island basalts (W/U OIB = 0.63 ± 0.07, n = 10), and back-arc basin basalts (W/U BABB = 0.62 ± 0.09, n = 12). This ratio is also consistent with the W/U ratio of the continental crust, and thus represents the W/U ratio of the entire silicate portion of the Earth. Assuming a concentration of 20 ± 8 (2 σ) ng/g U in the bulk silicate Earth, the abundance of W in the silicate Earth is 13 ± 10 ng/g. Following mass balance, this implies a mean modern mantle and core composition of 8.3 ± 7.1 ng/g W and 500 ± 120 ng/g W, respectively. Additionally, the MORB source is modeled to contain approximately 3.0 ± 2.3 ng/g W, indicating a four-fold depletion of the highly incompatible elements in the MORB source relative to the silicate Earth. Although both the isotopic composition of W and the constancy of the silicate Earth W/U ratio allow for potential insight into core-mantle exchange, both of these proxies are extremely dependent on the chemical composition of the source. A case study of three Hawaiian picrites with enrichments in 186Os- 187Os but terrestrial ɛ182W can be explained by: i) a lack of a core component in the Hawaiian "plume," ii) crustal contamination, or iii) a

  20. 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)

  1. 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. PMID:24009098

  2. Geochemistry

    SciTech Connect

    Foster, N.H.; Beaumont, E.A.

    1988-01-01

    Papers in this text are part of a reprint series designed to be useful to those involved in petroleum exploration and development. The authors divide the topic of geochemistry into four sections: (1) petroleum formation,(2) source rock evaluation, (3) migration, and (4) surface geochemistry. Petroleum formation contains papers that discuss accumulation and preservation of organic matter, conversion to kerogen, conversion to petroleum, and effects that different types of kerogen have on the types of petroleum generated. The section on source rocks contain papers that review methods for estimating total organic content of source rocks, potential amount of petroleum they can expel, and quantity of petroleum expelled from these source rocks.Migration deals with mechanisms for expulsion and migration of petroleum from source rocks and in carrier beds. The section on surface geochemistry discusses the problems associated with using geochemical methods in exploration.

  3. 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

  4. Tracking Iceland Plume Motion Using Trace Element Geochemistry

    NASA Astrophysics Data System (ADS)

    Fitton, J. G.; Walters, R. L.; Jones, S. M.

    2011-12-01

    The Greenland-Scotland Ridge (GSR) is a hotspot track built by interaction between the Mid Atlantic Ridge (MAR) and the Iceland mantle plume. Unlike most other hotspot tracks built by ridge-plume interaction, the GSR is 2 to 3 times wider than the plume conduit in the upper mantle. (This unusual wide morphology arises because Icelandic crust changes significantly in thickness within a few million years of accretion, probably mainly by viscous flow in the hot lower crust). The upshot is that the GSR cannot be compared directly with theoretical plume tracks from hotspot reference frame models. However, it is possible to track the position of the Iceland plume conduit using the trace element geochemistry of basaltic lavas. Away from the plume conduit, plate spreading drives upwelling of mantle through the melting region. Above the plume conduit, plume-driven flow forces mantle through the lower part of the melting region faster than the plate-driven upwelling rate. The average depth of melting is therefore greater directly above the plume conduit than away from the plume conduit, and this difference in average melting depth means that melts generated directly above the plume conduit are relatively enriched in incompatible trace elements. Joint modelling of trace element compositions and crustal thickness can also be used to establish location of melting relative to the plume conduit. To date, these concepts have been used only to explain compositional variations in modern (post-glacial) Icelandic lavas; in this study we show that the same concepts can be applied to map the location of the plume conduit throughout the onshore Icelandic geological record (since the middle Miocene, c. 16 Ma). The plume track thus determined is in reasonable agreement with theoretical tracks calculated under the assumption that the Iceland Plume has remained fixed relative to other Indo-Atlantic hotspots. This result also supports the idea that episodic relocations of the onshore part of

  5. Experimental constraints on light elements in the Earth's outer core.

    PubMed

    Zhang, Youjun; Sekine, Toshimori; He, Hongliang; Yu, Yin; Liu, Fusheng; Zhang, Mingjian

    2016-01-01

    Earth's outer core is liquid and dominantly composed of iron and nickel (~5-10 wt%). Its density, however, is ~8% lower than that of liquid iron, and requires the presence of a significant amount of light element(s). A good way to specify the light element(s) is a direct comparison of density and sound velocity measurements between seismological data and those of possible candidate compositions at the core conditions. We report the sound velocity measurements of a model core composition in the Fe-Ni-Si system at the outer core conditions by shock-wave experiments. Combining with the previous studies, we found that the best estimate for the outer core's light elements is ~6 wt% Si, ~2 wt% S, and possible ~1-2.5 wt% O. This composition satisfies the requirements imposed by seismology, geochemistry, and some models of the early core formation. This finding may help us to further constrain the thermal structure of the Earth and the models of Earth's core formation. PMID:26932596

  6. 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.

  7. 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.

  8. 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.

  9. Sedimentology, Geochemistry, and Geophysics of the Cambrian Earth System

    NASA Astrophysics Data System (ADS)

    Creveling, Jessica Renee

    Within this dissertation, I document how—and hypothesize why—the quirks and qualities of the Cambrian Period demarcate this interval as fundamentally different from the preceding Proterozoic Eon and succeeding periods of the Phanerozoic Eon. To begin, I focus on the anomalous marine deposition of the mineral apatite. Sedimentary sequestration of phosphorus modulates the capacity for marine primary productivity and, thus, the redox state of the Earth system. Moreover, sedimentary apatite minerals may entomb and replicate skeletal and soft-tissue organisms, creating key aspects of the fossil record from which paleontologists deduce the trajectory of animal evolution. I ask what geochemical redox regime promoted the delivery of phosphorus to Cambrian seafloors and conclude that, for the case of the Thorntonia Limestone, apatite nucleation occurred under anoxic, ferruginous subsurface water masses. Moreover, I infer that phosphorus bound to iron minerals precipitated from the water column and organic-bound phosphorus were both important sources of phosphorus to the seafloor. Petrographic observations allow me to reconstruct the early diagenetic pathways that decoupled phosphorus from these delivery shuttles and promoted the precipitation of apatite within the skeletons of small animals. Together, mechanistic understandings of phosphorus delivery to, and retention within, seafloor sediment allow us to constrain hypotheses for the fleeting occurrence of widespread apatite deposition and exquisite fossil preservation within Cambrian sedimentary successions. Next, I describe and quantify the nature of carbonate production on a marine platform deposited at the hypothesized peak of Cambrian skeletal carbonate production. I find that fossils represent conspicuous, but volumetrically subordinate components of early Cambrian carbonate reef ecosystems and that despite the evolution of mineralized skeletons, Cambrian carbonate platforms appear similar to their Neoproterozoic

  10. 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

  11. 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.

  12. 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 ...

  13. 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+).

  14. Rare earth element systematics in hydrothermal fluids

    SciTech Connect

    Michard, A. )

    1989-03-01

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

  15. 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.

  16. Light element geochemistry of the Apollo 16 site

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Kaplan, I. R.; Petrowski, C.; Chang, S.

    1975-01-01

    The abundance and isotopic composition of carbon, sulfur, and nitrogen, the abundance of helium and hydrogen, and the content of metallic iron are reported for lunar surface samples from the Apollo 16 landing site at Cayley-Descartes. The light elements show marked interstation variability at the site. The abundances in soils of C, N, He, and H are apparently controlled mainly by exposure to the solar wind, through implantation or stripping processes. Carbon abundances (but not observed isotopic distributions) are compatible with a model in which equilibrium is established after 10,000-100,000 yr between solar wind input and loss by proton stripping. Sulfur abundances in soils are apparently controlled by abundances in local country rocks, but the lunar S cycle is quite complex. A metallic iron component may have originated by solar wind reduction of lunar Fe(2+).

  17. Regional geochemistry of trace elements in Chesapeake Bay sediments

    NASA Astrophysics Data System (ADS)

    Sinex, S. A.; Helz, G. R.

    1981-11-01

    The concentrations of Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb in 177 surface sediment samples from throughout Chesapeake Bay are reported. Analyses were made of both unfractionated samples and the <63 μm fractions. Analytical uncertainty, always less than ±10%, controlled reproducibility in analyses of the <63 μm fractions, but sampling variance controlled reproducibility in the unfractionated samples, especially when coarse-grained sediments were being analyzed. Sediments in the northernmost part of the bay are enriched relative to average continental crust in all elements except Cr. This reflects the composition of dissolved and suspended material being delivered to that region by the Susquehanna River. The enriched sediments appear not to be transported south of Baltimore in significant quantily. Zinc, cadmium, and lead are enriched relative to average crust throughout the bay and in most other estuaries in the eastern United States.

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

    PubMed

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

    2013-12-01

    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. PMID:24387481

  19. 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.

  20. 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

  1. Siderophile elements and the earth's formation

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Capobianco, C. J.; Drake, M. J.; O'Neill, Hugh

    1992-01-01

    Two comments on a work by Murthy (1991) concerning the abundances of siderophile elements in the earth's mantle are presented. In the first comment it is asserted that the basis of Murthy's extrapolation is the assumption that the Gibbs free energy change for the partitioning reaction is independent of temperature, and as this is generally not a valid assumption thermodynamically, and as this is contradicted by most experimental data, the issue of mantle siderophile elements remains unresolved. In the second comment it is asserted that the extrapolation method used by Murthy does not appear to be valid thermodynamically, and that an extrapolation based on generally accepted thermodynamic assumptions yields different results. In a reply, Murthy takes issue with the comments.

  2. 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.

  3. [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. PMID:26117900

  4. Rare earth elements materials production from apatite ores

    NASA Astrophysics Data System (ADS)

    Anufrieva, A. V.; Andrienko, O. S.; Buynovskiy, A. S.; Makaseev, Y. N.; Mazov, I. N.; Nefedov, R. A.; Sachkov, V. I.; Stepanova, O. B.; Valkov, A. V.

    2016-01-01

    The paper deals with the study of processing apatite ores with nitric acid and extraction of the rare earth elements. The rare earth elements can be successfully separated and recovered by extraction from the nitrate- phosphate solution, being an tributyl phosphate as extraction agent. The developed scheme of the processing apatite concentrate provides obtaining rare earth concentrates with high qualitative characteristics.

  5. 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).

  6. Calculation of binary phase diagrams between the actinide elements, rare earth elements, and transition metal elements

    SciTech Connect

    Selle, J E

    1992-06-26

    Attempts were made to apply the Kaufman method of calculating binary phase diagrams to the calculation of binary phase diagrams between the rare earths, actinides, and the refractory transition metals. Difficulties were encountered in applying the method to the rare earths and actinides, and modifications were necessary to provide accurate representation of known diagrams. To calculate the interaction parameters for rare earth-rare earth diagrams, it was necessary to use the atomic volumes for each of the phases: liquid, body-centered cubic, hexagonal close-packed, and face-centered cubic. Determination of the atomic volumes of each of these phases for each element is discussed in detail. In some cases, empirical means were necessary. Results are presented on the calculation of rare earth-rare earth, rare earth-actinide, and actinide-actinide diagrams. For rare earth-refractory transition metal diagrams and actinide-refractory transition metal diagrams, empirical means were required to develop values for the enthalpy of vaporization for rare earth elements and values for the constant (C) required when intermediate phases are present. Results of using the values determined for each element are presented.

  7. 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.

  8. 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.

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

    DOE Data Explorer

    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"

  10. 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.

  11. Statistical Constraints from Siderophile Elements on Earth's Accretion, Differentiation, and Initial Core Stratification

    NASA Astrophysics Data System (ADS)

    O'Rourke, J. G.; Stevenson, D. J.

    2015-12-01

    Abundances of siderophile elements in the primitive mantle constrain the conditions of Earth's core/mantle differentiation. Core growth occurred as Earth accreted from collisions between planetesimals and larger embryos of unknown original provenance, so geochemistry is directly related to the overall dynamics of Solar System formation. Recent studies claim that only certain conditions of equilibration (pressure, temperature, and oxygen fugacity) during core formation can reproduce the available data. Typical analyses, however, only consider the effects of varying a few out of tens of free parameters in continuous core formation models. Here we describe the Markov chain Monte Carlo method, which simultaneously incorporates the large uncertainties on Earth's composition and the parameterizations that describe elemental partitioning between metal and silicate. This Bayesian technique is vastly more computationally efficient than a simple grid search and is well suited to models of planetary accretion that involve a plethora of variables. In contrast to previous work, we find that analyses of siderophile elements alone cannot yield a unique scenario for Earth's accretion. Our models predict a wide range of possible light element contents for the core, encompassing all combinations permitted by seismology and mineral physics. Specifically, we are agnostic between silicon and oxygen as the dominant light element, and the addition of carbon or sulfur is also permissible but not well constrained. Redox conditions may have remained roughly constant during Earth's accretion or relatively oxygen-rich material could have been incorporated before reduced embryos. Pressures and temperatures of equilibration, likewise, may only increase slowly throughout accretion. Therefore, we do not necessarily expect a thick (>500 km), compositionally stratified layer that is stable against convection to develop at the top of the core of Earth (or, by analogy, Venus). A thinner stable layer

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Rare earth elements in the Amazon basin

    NASA Astrophysics Data System (ADS)

    Gerard, M.; Seyler, P.; Benedetti, M. F.; Alves, V. P.; Boaventura, G. R.; Sondag, F.

    2003-05-01

    The rare earth element (REE) concentrations of the dissolved and particulate fractions and bed sediment between Manaus and Santarém in the Amazon River, and in some major tributaries, were evaluated. A very important zone in the Amazon basin, the encontro das aguas area where the Rio Solimões and the Rio Negro meet, was especially sampled. Different size fractions were isolated by ultrafiltration. Water samples were collected at different stages of the mixing. Three groups of waters are distinguished: group I has a low pH (<5·5) and is represented by the Negro basin rivers; group II has alkalinity less than 0·2 meq l-1 and is represented by the Rios Tapajós and Trombetas; group III has high alkalinity (>0·2 meq l-1) and higher pH (>6·5) and is represented by the Madeira basin rivers, the Solimões and the Amazon. The highest dissolved REE concentration is in the Rio Negro and the lowest in the Rio Tapajós (dissolved REEs vary by more than a factor of ten). The solubility of REEs is pH dependent: in river waters with a pH < 6 the Ce concentration is twice that of La, whereas in rivers with a higher pH the concentrations of Ce and La are similar. Dissolved REE concentrations are positively correlated with the dissolved organic carbon. Correlations between Fe, Al, and La suggest that La is associated with Al (Fe)-rich organic matter and/or related to dissolved Fe-rich inorganic material. Dissolved REEs normalized to North American shale composite show an enrichment in intermediate/heavy REEs (from Eu to Er), except for the shields rivers (such as Rio Negro and Rio Trombetas). Both of them are depleted in heavy REEs and show a relative Ce enrichment. In contrast, for the Andeans rivers (such as Rio Solimões), light REEs are slightly depleted and a negative Ce relative anomaly occurs. The pattern of the Amazon River at Óbidos confirms the major influence of the Rios Negro and Solimões with REE fractionation. For the Rio Negro, 60 to 70% of REEs are

  17. 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.

  18. 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.

  19. Rare earth element association with foraminifera

    NASA Astrophysics Data System (ADS)

    Roberts, Natalie L.; Piotrowski, Alexander M.; Elderfield, Henry; Eglinton, Timothy I.; Lomas, Michael W.

    2012-10-01

    Neodymium isotopes are becoming widely used as a palaeoceanographic tool for reconstructing the source and flow direction of water masses. A new method using planktonic foraminifera which have not been chemically cleaned has proven to be a promising means of avoiding contamination of the deep ocean palaeoceanographic signal by detrital material. However, the exact mechanism by which the Nd isotope signal from bottom waters becomes associated with planktonic foraminifera, the spatial distribution of rare earth element (REE) concentrations within the shell, and the possible mobility of REE ions during changing redox conditions, have not been fully investigated. Here we present REE concentration and Nd isotope data from mixed species of planktonic foraminifera taken from plankton tows, sediment traps and a sediment core from the NW Atlantic. We used multiple geochemical techniques to evaluate how, where and when REEs become associated with planktonic foraminifera as they settle through the water column, reside at the surface and are buried in the sediment. Analyses of foraminifera shells from plankton tows and sediment traps between 200 and 2938 m water depth indicate that only ˜20% of their associated Nd is biogenically incorporated into the calcite structure. The remaining 80% is associated with authigenic metal oxides and organic matter, which form in the water column, and remain extraneous to the carbonate structure. Remineralisation of these organic and authigenic phases releases ions back into solution and creates new binding sites, allowing the Nd isotope ratio to undergo partial equilibration with the ambient seawater, as the foraminifera fall through the water column. Analyses of fossil foraminifera shells from sediment cores show that their REE concentrations increase by up to 10-fold at the sediment-water interface, and acquire an isotopic signature of bottom water. Adsorption and complexation of REE3+ ions between the inner layers of calcite contributes

  20. 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.

  1. 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

    2014-04-01

    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. PMID:24695310

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  3. The relationship between soil geochemistry and the bioaccessibility of trace elements in playground soil.

    PubMed

    De Miguel, Eduardo; Mingot, Juan; Chacón, Enrique; Charlesworth, Susanne

    2012-12-01

    A total of 32 samples of surficial soil were collected from 16 playground areas in Madrid (Spain), in order to investigate the importance of the geochemistry of the soil on subsequent bioaccessibility of trace elements. The in vitro bioaccessibility of As, Co, Cr, Cu, Ni, Pb and Zn was evaluated by means of two extraction processes that simulate the gastric environment and one that reproduces a gastric + intestinal digestion sequence. The results of the in vitro bioaccessibility were compared against aqua regia extractions ("total" concentration), and it was found that total concentrations of As, Cu, Pb and Zn were double those of bioaccessible values, whilst that of Cr was ten times higher. Whereas the results of the gastric + intestinal extraction were affected by a high uncertainty, both gastric methods offered very similar and consistent results, with bioaccessibilities following the order: As = Cu = Pb = Zn > Co > Ni > Cr, and ranging from 63 to 7 %. Selected soil properties including pH, organic matter, Fe and CaCO(3) content were determined to assess their influence on trace element bioaccessibility, and it was found that Cu, Pb and Zn were predominantly bound to organic matter and, to a lesser extent, Fe oxides. The former fraction was readily accessible in the gastric solution, whereas Fe oxides seemed to recapture negatively charged chloride complexes of these elements in the gastric solution, lowering their bioaccessibility. The homogeneous pH of the playground soils included in the study does not influence trace element bioaccessibility to any significant extent except for Cr, where the very low gastric accessibility seems to be related to the strongly pH-dependent formation of complexes with organic matter. The results for As, which have been previously described and discussed in detail in Mingot et al. (Chemosphere 84: 1386-1391, 2011), indicate a high gastric bioaccessibility for this element as a consequence of its strong association with calcium

  4. 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.

  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. PMID:26332985

  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. 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.

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

    USGS Publications Warehouse

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

    1957-01-01

    In a continuation of a study reported previously, rare-earth elements and thorium have been determined in monazite, allanite, cerite, bastnaesite, and a number of miscellaneous cerium-earth minerals. A quantity called sigma (???), which is the sum of the atomic percentages of La, Ce, and Pr, is proposed as an index of composition of all cerium-earth minerals with respect to the rare-earth elements. The value of ??? for all of the minerals analysed falls between 58 and 92 atomic per cent. Monazites, allanites, and cerites cover the entire observed range, whereas bastnaesites are sharply restricted to the range between 80 and 92 atomic per cent. The minimum value of ??? for a cerium-earth mineral corresponds to the smallest possible unit-cell size of the mineral. In monazite, this structurally controlled minimum value of ??? is estimated to be around 30 atomic per cent. Neodymium, because of its abundance, and yttrium, because of its small size, have dominant roles in contraction of the structure. In the other direction, the limit of variation in composition will be reached when lanthanum becomes the sole rare-earth element in a cerium-earth mineral. Cerium-earth minerals from alkalic rocks are all characterized by values of ??? greater than 80 atomic per cent, indicating that the processes that formed these rocks were unusually efficient in fractionating the rare-earth elements-efficient in the sense that a highly selected assemblage is produced without eliminating the bulk of these elements. Analyses of inner and outer parts of two large crystals of monazite from different deposits show no difference in ??? in one crystal and a slightly smaller value of ??? in the outer part of the other crystal compared to the inner part. The ??? of monazites from pegmatites that intrude genetically related granitic rocks in North Carolina is found to be either higher or lower than the ??? of monazites in the intruded host rock. These results indicate that the fractionation of the

  10. 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.

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

    DOE Data Explorer

    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.

  12. 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.

  13. 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

  14. Anthropogenic disturbance of element cycles at the Earth's surface.

    PubMed

    Sen, Indra S; Peucker-Ehrenbrink, Bernhard

    2012-08-21

    The extent to which humans are modifying Earth's surface chemistry can be quantified by comparing total anthropogenic element fluxes with their natural counterparts (Klee and Graedel, 2004). We quantify anthropogenic mass transfer of 77 elements from mining, fossil fuel burning, biomass burning, construction activities, and human apportionment of terrestrial net primary productivity, and compare it to natural mass transfer from terrestrial and marine net primary productivity, riverine dissolved and suspended matter fluxes to the ocean, soil erosion, eolian dust, sea-salt spray, cosmic dust, volcanic emissions, and for helium, hydrodynamic escape from the Earth's atmosphere. We introduce an approach to correct for losses during industrial processing of elements belonging to geochemically coherent groups, and explicitly incorporate uncertainties of element mass fluxes through Monte Carlo simulations. We find that at the Earth's surface anthropogenic fluxes of iridium, osmium, helium, gold, ruthenium, antimony, platinum, palladium, rhenium, rhodium and chromium currently exceed natural fluxes. For these elements mining is the major factor of anthropogenic influence, whereas petroleum burning strongly influences the surficial cycle of rhenium. Our assessment indicates that if anthropogenic contributions to soil erosion and eolian dust are considered, anthropogenic fluxes of up to 62 elements surpass their corresponding natural fluxes. PMID:22803636

  15. 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.

  16. Geochemistry of rare and minor elements in sediments from Brazil Basin of Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Vvedenskaya, Irina; Dubinin, Alexander

    2010-05-01

    diatom oozes, compared with the clayey silts, contain higher concentrations of Co, Cu, Ni, Mo, Tl. The content of other minor elements is considerably lower than that of the clayey silts. Comparison of the average chemical element contents in miopelagic clay and diatom oozes gives a series sequence of abundance of minor elements: Ag Mo Tl Mn Cd Ba Co Ni Cu Sr Pb Li Ce Zn V 0.2 0.4 0.5 0.5 0.6 1.2 1.3 1.5 1.7 1.8 2.1 2.1 2.1 2.1 2.3 REE Y U W Th Be Rb Cs As 2.3-2.1 2.3 2.4 2.4 2.4 2.4 2.4 2.5 3.5 The miopelagic muds contains high concentrations are reached in three groups of elements: easily hydrolyze elements (REE, Y, Th, Be), elements represented by oxyanions in the ocean water (U, W, V, As) and elements linked with the clays (Li, Rb, Cs). The concentrations of rare earth elements (REE) in miopelagic muds show almost no change with depth. The compositions of REE include cerium anomaly and light lanthanides. The composition of REE in diatom oozes is more variable. The oozes also include cerium anomaly, but sometimes concentrations of lighter elements are low.

  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. PMID:26375205

  18. 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

  19. 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. PMID:21390524

  20. Isotope and trace element geochemistry of lamprophyres and syenites from different areas of South-Chuya complex, SE Altai.

    NASA Astrophysics Data System (ADS)

    Vasyukova, Elena

    2016-04-01

    Major and trace elements and radiogenic isotope data are reported for lamprophyres and syenites of South-Chuya complex associated with ore districts in South East of Gornyi Altai, Russia. Dikes of lamprophyres form big area, elongated from north-west to south-east. Within the area of complex dikes distribute irregularly accompanied the fault zones. Lamprophyres of three largest areas, named Aktash, South Chuya and Yustyd were characterized in terms of geology, petro- and geochemistry, isotopic composition. Some of the lamprophyres judging by the high mg'>60 reveal mantle signatures. They reveal round TRE patterns typical of the primitive low degree partial melts but with the negative Nb- Ta anomalies. The others with the lower mg' suggest their differentiation and contamination in crust material. They reveal slightly lower level of TRE and lower troughs of all HFSE. All dikes had intruded in the period of 250-235 Ma, have similar mineralogical, petro- and geochemistry characteristics which were the reasons for unite all of them in one complex. On the most of geochemistry diagrams dikes from 3 areas form their own, but intersected clusters. But on the isotopic diagrams (Sm/Nd and Rb/Sr systems) they show the principle dissimilarity between dikes from various areas. Yustyd lamprophyres initial isotopic characteristics are close to the BSE. The south-chuya rocks isotopic compositions are more enriched by 87Sr/86Sr and have negative ɛNd (-2.84..-4.05). Contamination by the lower crust material suggested at the early stage during the formation of the lamprophyres. Bu the Yustyd lamprophyres were contaminated also during the ascend by the upper crust. Two competitive hypotheses n the isotopic composition are dicussed: 1) different sources or 2) different proportions between the material from the same sources, which ensemble generate the parental magma for the rocks.

  1. 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. PMID:25613802

  2. 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.

  3. 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.

  4. 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

  5. Removal of Phosphorus in Metallurgical Silicon by Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Tang, Kai; Løvvik, Ole Martin; Safarian, Jafar; Ma, Xiang; Tangstad, Merete

    2014-09-01

    Removal of phosphorus in metallurgical silicon is one of the crucial steps for the production of solar grade Si feedstock. The possibility of doping rare earth elements for phosphorus removal has in this work been studied both theoretically and experimentally. Thermochemical properties of Ce, Nd, and Pr monophosphides have first been estimated by ab initio thermodynamic simulations based on density functional theory and the direct phonon method. The reliability of the first principles calculations was assessed by coupling with the phase diagram data of the Pr-P system. Equilibrium calculations confirmed the existence of stable rare earth monophosphides in solid silicon. Experimental investigations were then carried out, employing a high temperature resistance furnace. The Ce-doped silicon samples were examined by electron probe micro analyzer and inductively coupled plasma analysis. The efficiency of phosphorus removal by means of rare earth doping was discussed in detail in the paper.

  6. 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.

  7. Spherical disharmonics in the Earth sciences and the spatial solution: Ridges, hotspots, slabs, geochemistry and tomography correlations

    NASA Technical Reports Server (NTRS)

    Ray, Terrill W.; Anderson, Don L.

    1994-01-01

    There is increasing use of statistical correlations between geophysical fields and between geochemical and geophysical fields in attempts to understand how the Earth works. Typically, such correlations have been based on spherical harmonic expansions. The expression of functions on the sphere as spherical harmonic series has many pitfalls, especially if the data are nonuniformly and/or sparsely sampled. Many of the difficulties involved in the use of spherical harmonic expansion techniques can be avoided through the use of spatial domain correlations, but this introduces other complications, such as the choice of a sampling lattice. Additionally, many geophysical and geochemical fields fail to satisfy the assumptions of standard statistical significance tests. This is especially problematic when the data values to be correlated with a geophysical field were collected at sample locations which themselves correlate with that field. This paper examines many correlations which have been claimed in the past between geochemistry and mantle tomography and between hotspot, ridge, and slab locations and tomography using both spherical harmonic coefficient correlations and spatial domain correlations. No conclusively significant correlations are found between isotopic geochemistry and mantle tomography. The Crough and Jurdy (short) hotspot location list shows statistically significant correlation with lowermost mantle tomography for degree 2 of the spherical harmonic expansion, but there are no statistically significant correlations in the spatial case. The Vogt (long) hotspot location list does not correlate with tomography anywhere in the mantle using either technique. Both hotspot lists show a strong correlation between hotspot locations and geoid highs when spatially correlated, but no correlations are revealed by spherical harmonic techniques. Ridge locations do not show any statistically significant correlations with tomography, slab locations, or the geoid; the

  8. 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 id="translatedtitle"><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://www.osti.gov/scitech/biblio/7034520','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7034520"><span id="translatedtitle">Rare-<span class="hlt">earth</span> <span class="hlt">element</span> variation in phosphate nodules from midcontinent Pennsylvanian cyclothems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kidder, D.L. . Dept. of Geological Sciences); Eddy-Dilek, C.A. . Savannah River Technology Center)</p> <p>1994-07-01</p> <p>The rare-<span class="hlt">earth</span> <span class="hlt">element</span> (REE) <span class="hlt">geochemistry</span> of phosphate nodules from eastern Kansas and northeastern Oklahoma is dominated by patterns that are generally flat or are enriched in middle REE (MREE). Flat patterns are typical of phosphate nodules preserved in thick shales and in nodules from shales deposited nearest to detrital sources. The flat patterns are probably derived from terrigenous constituents in the host shale. MREE enrichment is evident in phosphate found in relatively thin shales and in distal shales. The authors suggest that the MREE-enriched pattern reflects the contribution of MREE-enriched fecal phosphate. The initial MREE enrichment mechanism may have been analogous to that in which some modern algae preferentially extract MREE from water of marine composition. The MREE-enriched signature may be preserved only in phosphate nodules that formed where terrigenous input was so low that it did not mask the characteristic fecal pattern. Rare Ce depletion patterns reflect a primary seawater REE source that has not been obscured by fecal or detrital components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026818','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026818"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> partitioning between hydrous ferric oxides and acid mine water during iron oxidation</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.; Nordstrom, D.K.; Taylor, H.E.; Kimball, B.A.</p> <p>2004-01-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">element</span> (REE) <span class="hlt">geochemistry</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3216626','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3216626"><span id="translatedtitle">Uncovering the Global Life Cycles of the 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>Du, Xiaoyue; Graedel, T. E.</p> <p>2011-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are a group of fifteen <span class="hlt">elements</span> 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 <span class="hlt">elements</span>. PMID:22355662</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 id="translatedtitle">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/2012AGUFMGC53C1290S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGC53C1290S"><span id="translatedtitle">Anthropogenic Disturbance of <span class="hlt">Element</span> Cycles at the <span class="hlt">Earth</span>'s Surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sen, I. S.; Peucker-Ehrenbrink, B.</p> <p>2012-12-01</p> <p>The extent to which humans are modifying <span class="hlt">Earth</span>'s surface chemistry can be quantified by comparing total anthropogenic <span class="hlt">element</span> fluxes with their natural counterparts [1]. We determine anthropogenic mass transfer of 77 <span class="hlt">elements</span> from mining, fossil fuel burning, biomass burning, construction activities, and human apportionment of terrestrial net primary productivity, and compared it to natural mass transfer from terrestrial and marine net primary productivity, riverine dissolved and suspended matter fluxes to the ocean, soil erosion, eolian dust, sea-salt spray, cosmic dust, volcanic emissions and - for helium - hydrodynamic escape from the <span class="hlt">Earth</span>'s atmosphere. In addition, we introduce an approach to correct for losses during industrial processing of <span class="hlt">elements</span> belonging to geochemically coherent groups, and explicitly incorporated uncertainties of <span class="hlt">element</span> mass fluxes through Monte Carlo simulations [2]. Our assessment indicates that anthropogenic fluxes of iridium, osmium, helium, gold, ruthenium, antimony, platinum, palladium, rhenium, rhodium and chromium are greater than the respective natural fluxes. For these <span class="hlt">elements</span> mining is the major factor of human dominance, whereas petroleum burning strongly influence the surficial cycle of rhenium. Apart from these 11 <span class="hlt">elements</span> there are 15 additional <span class="hlt">elements</span> whose anthropogenic fluxes may surpass their corresponding natural fluxes. Anthropogenic fluxes of the remaining <span class="hlt">elements</span> are smaller than their corresponding natural fluxes although a significant human influence is observed for all of them. For example, ~20% of the annual fluxes of C, N, and P can be attributed to human activities. Such disturbances, though small compared with natural fluxes, can significantly alter concentrations in near-surface reservoirs and affect ecosystems if they are sustained over time scales similar to or longer than the residence time of <span class="hlt">elements</span> in the respective reservoir. Examples are the continuing input of CO2 to the atmosphere that</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 id="translatedtitle">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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Sci...343C.386M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Sci...343C.386M"><span id="translatedtitle"><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="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</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.; Kemppinen, Osku; Bridges, Nathan; Johnson, Jeffrey R.; Minitti, Michelle; Cremers, David; Farmer, Jack; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; Blank, Jennifer; Weigle, Gerald; Li, Shuai; Milliken, Ralph; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Farley, Kenneth; Griffes, Jennifer; Miller, Hayden; Newcombe, Megan; Pilorget, Cedric; Siebach, Kirsten; Brunet, Claude; Hipkin, Victoria; Marchand, Geneviève; Sánchez, Pablo Sobrón; Favot, Laurent; Cody, George; Steele, Andrew; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Armiens-Aparicio, Carlos; Rodríguez, Javier Caride; Blázquez, Isaías Carrasco; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Hettrich, Sebastian; Malvitte, Alain Lepinette; Jiménez, Mercedes Marín; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F. Javier; Jurado, Antonio Molina; Mora-Sotomayor, Luis; Caro, Guillermo Muñoz; López, Sara Navarro; Peinado-González, Verónica; Pla-García, Jorge; Manfredi, José Antonio Rodriguez; Romeral-Planelló, Julio José; Fuentes, Sara Alejandra Sans; Martinez, Eduardo Sebastian; Redondo, Josefina Torres; Urqui-O'Callaghan, Roser; Mier, María-Paz Zorzano; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairén, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Sullivan, Robert; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Kemppinen, Osku; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Wray, James; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Bish, David; Schieber, Juergen; Gondet, Brigitte; Langevin, Yves; Geffroy, Claude; Baratoux, David; Berger, Gilles; Cros, Alain; d'Uston, Claude; Lasue, Jérémie; Lee, Qiu-Mei; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schröder, Susanne; Toplis, Mike; Lewin, Éric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Israël, Guy; Szopa, Cyril; Robert, François; Sautter, Violaine; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; François, Pascaline; Raulin, François; Teinturier, Samuel; Cameron, James; DeLapp, Dorothea; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Lanza, Nina; Little, Cynthia; Nelson, Tony; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Edgett, Kenneth; Fay, Donald; Hardgrove, Craig; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; Malin, Michael; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Van Beek, Tessa; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Summons, Roger; Goesmann, Fred; Goetz, Walter; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Fassett, Caleb; Blake, David F.; Bristow, Thomas; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Wilhelm, Mary Beth; Bleacher, Lora; Brinckerhoff, William; Choi, David; Dworkin, Jason P.; Eigenbrode, Jennifer; Floyd, Melissa; Freissinet, Caroline; Garvin, James; Glavin, Daniel; Harpold, Daniel; Jones, Andrea; Mahaffy, Paul; Martin, David K.; McAdam, Amy; Pavlov, Alexander; Raaen, Eric; Smith, Michael D.; Stern, Jennifer; Tan, Florence; Trainer, Melissa; Meyer, Michael; Posner, Arik; Voytek, Mary; Anderson, Robert C.; Aubrey, Andrew; Beegle, Luther W.; Behar, Alberto; Blaney, Diana; Brinza, David; Christensen, Lance; Crisp, Joy A.; DeFlores, Lauren; Ehlmann, Bethany; Feldman, Jason; Feldman, Sabrina; Flesch, Gregory; Jun, Insoo; Keymeulen, Didier; Maki, Justin; Mischna, Michael; Morookian, John Michael; Parker, Timothy; Pavri, Betina; Schoppers, Marcel; Sengstacken, Aaron; Simmonds, John J.; Spanovich, Nicole; Juarez, Manuel de la Torre; Webster, Christopher R.; Yen, Albert; Archer, Paul Douglas; Cucinotta, Francis; Jones, John H.; Niles, Paul; Rampe, Elizabeth; Nolan, Thomas; Fisk, Martin; Radziemski, Leon; Barraclough, Bruce; Bender, Steve; Berman, Daniel; Dobrea, Eldar Noe; Tokar, Robert; Williams, Rebecca M. E.; Cleghorn, Timothy; Huntress, Wesley; Manhès, Gérard; Hudgins, Judy; Olson, Timothy; Stewart, Noel; Sarrazin, Philippe; Vicenzi, Edward; Wilson, Sharon A.; Bullock, Mark; Ehresmann, Bent; Hamilton, Victoria; Hassler, Donald; Peterson, Joseph; Rafkin, Scot; Zeitlin, Cary; Fedosov, Fedor; Golovin, Dmitry; Karpushkina, Natalya; Kozyrev, Alexander; Litvak, Maxim; Malakhov, Alexey; Mitrofanov, Igor; Mokrousov, Maxim; Nikiforov, Sergey; Prokhorov, Vasily; Sanin, Anton; Tretyakov, Vladislav; Varenikov, Alexey; Vostrukhin, Andrey; Kuzmin, Ruslan; Wolff, Michael; Botta, Oliver; Drake, Darrell; Bean, Keri; Lemmon, Mark; Lee, Ella Mae; Sucharski, Robert; Hernández, Miguel Ángel de Pablo; Ávalos, Juan José Blanco; Ramos, Miguel; Kim, Myung-Hee; Malespin, Charles; Plante, Ianik; Muller, Jan-Peter; Navarro-González, Rafael; Ewing, Ryan; Boynton, William; Downs, Robert; Fitzgibbon, Mike; Harshman, Karl; Morrison, Shaunna; Dietrich, William; Kortmann, Onno; Palucis, Marisa; Williams, Amy; Lugmair, Günter; Wilson, Michael A.; Rubin, David; Jakosky, Bruce; Balic-Zunic, Tonci; Frydenvang, Jens; Jensen, Jaqueline Kløvgaard; Kinch, Kjartan; Koefoed, Asmus; Madsen, Morten Bo; Stipp, Susan Louise Svane; Boyd, Nick; Pradler, Irina; Jacob, Samantha; Owen, Tobias; Rowland, Scott; Atlaskin, Evgeny; Savijärvi, Hannu; Boehm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Guo, Jingnan; Köhler, Jan; García, César Martín; Mueller-Mellin, Reinhold; Wimmer-Schweingruber, Robert; McConnochie, Timothy; Benna, Mehdi; Franz, Heather; Bower, Hannah; Brunner, Anna; Blau, Hannah; Boucher, Thomas; Carmosino, Marco; Atreya, Sushil; Elliott, Harvey; Halleaux, Douglas; Rennó, Nilton; Wong, Michael; Pepin, Robert; Elliott, Beverley; Spray, John; Thompson, Lucy; Williams, Joshua; Vasconcelos, Paulo; Bentz, Jennifer; Nealson, Kenneth; Popa, Radu; Kah, Linda C.; Moersch, Jeffrey; Tate, Christopher; Day, Mackenzie; Kocurek, Gary; Hallet, Bernard; Sletten, Ronald; Francis, Raymond; McCullough, Emily; Cloutis, Ed; ten Kate, Inge Loes; Kuzmin, Ruslan; Arvidson, Raymond; Fraeman, Abigail; Scholes, Daniel; Slavney, Susan; Stein, Thomas; Ward, Jennifer; Berger, Jeffrey; Moores, John E.</p> <p>2014-01-01</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('http://www.ncbi.nlm.nih.gov/pubmed/24324274','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24324274"><span id="translatedtitle"><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="http://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. PMID:24324274</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26595776','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26595776"><span id="translatedtitle">Assessing rare <span class="hlt">earth</span> <span class="hlt">elements</span> in quartz rich geological samples.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Santoro, A; Thoss, V; Guevara, S Ribeiro; Urgast, D; Raab, A; Mastrolitti, S; Feldmann, J</p> <p>2016-01-01</p> <p>Sodium peroxide (Na2O2) fusion coupled to Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) measurements was used to rapidly screen quartz-rich geological samples for rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) content. The method accuracy was checked with a geological reference material and Instrumental Neutron Activation Analysis (INAA) measurements. The used mass-mode combinations presented accurate results (only exception being (157)Gd in He gas mode) with recovery of the geological reference material QLO-1 between 80% and 98% (lower values for Lu, Nd and Sm) and in general comparable to INAA measurements. Low limits of detection for all <span class="hlt">elements</span> were achieved, generally below 10 pg g(-1), as well as measurement repeatability below 15%. Overall, the Na2O2/ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare <span class="hlt">earth</span> <span class="hlt">element</span> content; particularly useful if checking commercial viability. PMID:26595776</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1816699H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1816699H&link_type=ABSTRACT"><span id="translatedtitle">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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910053953&hterms=Zircon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DZircon','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910053953&hterms=Zircon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DZircon"><span id="translatedtitle">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> </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://www.osti.gov/scitech/biblio/5216629','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5216629"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2016AIPC.1726b0116Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1726b0116Z"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> content of cryptocrystalline magnesites of Konya, Turkey</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zedef, Veysel; Russell, Michael</p> <p>2016-04-01</p> <p>We examined the rare <span class="hlt">earth</span> <span class="hlt">element</span> content of several cryptocrystalline magnesites as well as hydromagnesite, host rock serpentinites, lake water and hot spring water from Turkey. Southwestern Turkey hosts cryptocrystalline magnesites, sedimentary magnesites with presently forming, biologically mediated hydromagnesites and travertines. Our results show the REE content of the minerals, rocks and waters are well below detection limits. One hydromagnesite sample from Lake Salda has slightly high La (2.38ppb), Ce (3.91 ppb) and Nd (1.68 ppb) when compared to other samples, but these are also still below detection limits of the method we followed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850024768&hterms=asthenosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dasthenosphere','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850024768&hterms=asthenosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dasthenosphere"><span id="translatedtitle">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://pubs.er.usgs.gov/publication/70023771','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023771"><span id="translatedtitle">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('http://hdl.handle.net/2060/19890011981','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890011981"><span id="translatedtitle">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/2006AGUFM.T21C0433T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.T21C0433T"><span id="translatedtitle"><span class="hlt">Elemental</span> <span class="hlt">Geochemistry</span> of Samples From Fault Segments of the San Andreas Fault Observatory at Depth (SAFOD) Drill Hole</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tourscher, S. N.; Schleicher, A. M.; van der Pluijm, B. A.; Warr, L. N.</p> <p>2006-12-01</p> <p><span class="hlt">Elemental</span> <span class="hlt">geochemistry</span> of mudrock samples from phase 2 drilling of the San Andreas Fault Observatory at Depth (SAFOD) is presented from bore hole depths of 3066 m to 3169 m and from 3292 m to 3368 m, which contain a creeping section and main trace of the fault, respectively. In addition to preparation and analysis of whole rock sample, fault grains with neomineralized, polished surfaces were hand picked from well-washed whole rock samples, minimizing the potential contamination from drilling mud and steel shavings. The separated fractions were washed in deionized water, powdered using a mortar and pestle, and analyzed using an Inductively Coupled Plasma- Optical Emission Spectrometer for major and minor <span class="hlt">elements</span>. Based on oxide data results, systematic differences in <span class="hlt">element</span> concentrations are observed between the whole rock and fault rock. Two groupings of data points are distinguishable in the regions containing the main trace of the fault, a shallow part (3292- 3316 m) and a deeper section (3320-3368 m). Applying the isocon method, assuming Zr and Ti to be immobile <span class="hlt">elements</span> in these samples, indicates a volume loss of more than 30 percent in the shallow part and about 23 percent in the deep part of the main trace. These changes are minimum estimates of fault-related volume loss, because the whole rock from drilling samples contains variable amount of fault rock as well. Minimum estimates for volume loss in the creeping section of the fault are more than 50 percent when using the isocon method, comparing whole rock to plucked fault rock. The majority of the volume loss in the fault rocks is due to the dissolution and loss of silica, potassium, aluminum, sodium and calcium, whereas (based on oxide data) the mineralized surfaces of fractures appear to be enriched in Fe and Mg. The large amount of <span class="hlt">element</span> mobility within these fault traces suggests extensive circulation of hydrous fluids along fractures that was responsible for progressive dissolution and leaching</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25848014','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25848014"><span id="translatedtitle">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="http://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. PMID:25848014</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4413328','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4413328"><span id="translatedtitle">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="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A. W.</p> <p>2015-01-01</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. PMID:25848014</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.B21C0451J&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.B21C0451J&link_type=ABSTRACT"><span id="translatedtitle">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('http://www.ncbi.nlm.nih.gov/pubmed/24489809','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24489809"><span id="translatedtitle">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=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. PMID:24489809</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3906100','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3906100"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/24662205','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24662205"><span id="translatedtitle">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="http://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. PMID:24662205</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5822533','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5822533"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of Muong-Nong type tektites. IV. Selected trace <span class="hlt">element</span> correlations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Koeberl, C.; Kluger, F.; Kiesl, W.</p> <p>1984-11-15</p> <p>Muong-Nong type tektites are distinct from other tektites in their shape, size, petrographical characteristics, and chemistry. Volatile <span class="hlt">elements</span> are enriched, but other trace <span class="hlt">elements</span> do not show large differences when compared to normal splash-form tektites. An analysis is made of nineteen Muong-Nong type tektites for 40-50 <span class="hlt">elements</span>. Fifteen nonvolatile <span class="hlt">elements</span> are discussed in this paper. It is shown that the Muong-Nong type tektites are very restricted in chemical composition and are almost indistinguishable from the Australasian tektites. <span class="hlt">Elemental</span> ratios calculated from the data reported here show the same genetic connection. All elementary abundances and ratios are fully consistent with terrestrial sediments. The nonvolatile <span class="hlt">elements</span> may record more about the conditions of the origin.</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 id="translatedtitle">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://pubs.er.usgs.gov/publication/70034362','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034362"><span id="translatedtitle"><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/1998NIMPA.405..590T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998NIMPA.405..590T"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of trace <span class="hlt">elements</span> in the highland lunar rocks based on SRXFA data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tarasov, L. S.; Kudryashova, A. F.; Ulyanov, A. A.; Baryshev, V. B.; Zolotarev, K. V.</p> <p>1998-02-01</p> <p>X-ray fluorescence analysis using synchrotron radiation (SRXFA) has been applied for determination of trace <span class="hlt">elements</span> in the highland lunar rocks (Luna 20 and Apollo 16). On the basis of the distribution of Rb, Sr, Y, Zr, and Nb in 69 lunar highland fragments six geochemical groups of rocks with various aluminium and trace <span class="hlt">element</span> contents were distinguished for each station. They have various levels of trace <span class="hlt">element</span> content. This suggests the various petrological processes: cumulation of rock-forming minerals and partial melting of source rocks. The last process lead up to enriching in trace <span class="hlt">elements</span> in rocks formed from these melts. The distribution of trace <span class="hlt">elements</span> in highland and mare rocks of the Moon were compared.</p> </li> <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 id="translatedtitle">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('http://pubs.usgs.gov/pp/1566/report.pdf','USGSPUBS'); return false;" href="http://pubs.usgs.gov/pp/1566/report.pdf"><span id="translatedtitle"><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('http://www.ncbi.nlm.nih.gov/pubmed/24202842','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24202842"><span id="translatedtitle">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="http://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. PMID:24202842</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMPP31B1328V&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMPP31B1328V&link_type=ABSTRACT"><span id="translatedtitle">RECONSTRUCTING LAURENTIDE ICE SHEET MELTWATER <span class="hlt">GEOCHEMISTRY</span> USING COMBINED STABLE ISOTOPE AND LASER ABLATION 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>Vetter, L.; Spero, H. J.; Eggins, S. M.; Flower, B. P.; Williams, C. C.</p> <p>2009-12-01</p> <p>Little is known about the oxygen isotope evolution of Northern hemisphere ice sheets during past glacial cycles, with the exception of results from models and calculations based on whole ocean δ18O change. Reconstructing changes in the δ18Owater of the global ocean assumes a homogeneous δ18O value for contributions from Northern hemisphere ice sheets with a mass balance contribution from the Southern hemisphere. Because oceanic δ18Ow forms a crucial baseline for deconvolving the combined signal of temperature and hydrologic changes recorded in foraminiferal calcite, constraints on the contributions of melting ice sheets form a fundamental component of reconstructions of global ocean δ18Ow changes on glacial timescales. Here we present a novel geochemical technique to compute the oxygen isotopic composition of Laurentide Ice Sheet (LIS) meltwater flowing into the Gulf of Mexico during periods of rapid ice sheet melting. The technique combines data from different types of geochemical analyses on individual shells of the planktonic foraminifera Orbulina universa to compute meltwater <span class="hlt">geochemistry</span>, using laser ablation ICP-MS to measure Mg/Ca (a temperature proxy) and Ba/Ca (a salinity proxy) and isotope ratio mass spectrometry to measure δ18O (a temperature and δ18Owater proxy) on remaining shell material. O. universa has a very large temperature and salinity tolerance (9-30°C; 23-45 psu) and broad depth habitat (0-80 m), so an assemblage of individual shells from a single core interval records a range of water conditions. We have selected deglacial meltwater intervals from core MD02-2550 (26.95°N, 91.35°W, 2245 m water depth), collected from the anoxic Orca Basin in the Gulf of Mexico, for a proof of concept demonstration. From each interval, we combine measurements of Mg/Ca, Ba/Ca, and δ18O on 30-100 individual O. universa. The δ18O from each shell reflects the combined influence of temperature and δ18Owater, where this latter value is a function of</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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GeCoA.170...17B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GeCoA.170...17B&link_type=ABSTRACT"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/1988E%26PSL..87..409C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988E%26PSL..87..409C"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> <span class="hlt">geochemistry</span> of an anorthosite-diorite suite, Namaqua mobile belt, South Africa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conradie, J. A.; Schoch, A. E.</p> <p>1988-03-01</p> <p>A swarm of small dyke-like plutons, ranging in composition from anorthosite through diorite and norite, to hypersthenite and glimmerite, occurs in the western part of the Namaqua mobile belt, South Africa. Known as the Koperberg Suite, these rocks host important magmatic sulphide deposits. Zircon ages of approximately 1100 Ma suggest that the suite was emplaced after the peak of the regional high-grade metamorphism, dated at 1200 Ma. A postulated comagmatic origin for the various rock types is confirmed by the REE distributions of anorthosite, leucodiorite, diorite, hypersthenite and glimmerite. The Koperberg Suite resembles the well-known massif anorthosite complexes, typified by the Adirondack Suite, in most properties except for the dispersed mode of occurrence. It is now shown that the similarity also holds for the REE spectra. Thus, the predominant anorthosite and leucodiorite of the Koperberg Suite are comparable to similar rocks of the Adirondacks and the Burwash area, Ontario, albeit more enriched in LREE. More mafic rock types such as norite, mica-diorite and glimmerite are substantially enriched in LREE compared to mafic differentiates of massif anorthosites. Apatite is abundant in the mafic rocks and stores large proportions of the lanthanides. The occurrence of apatite- and mica-rich assemblages indicates source magmas enriched in K, REE and P. A few intrusives exhibit excessively enriched REE patterns which are attributed to late hydrothermal alteration or metasomatism. The REE data for syenite and two-pyroxene assemblages from the Copper District argue against a genetic relationship to the Koperberg Suite in spite of close spatial association.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS41A1691G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS41A1691G"><span id="translatedtitle">Dissolved Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Concentrations in the Upwelling area off Peru</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grasse, P.; Plass, A.; Hathorne, E. C.; Frank, M.</p> <p>2012-12-01</p> <p>, especially of the light REEs, were found in surface waters. Shelf locations show an enrichment in light REEs with higher (La/Yb)PAAS ratios (~0.7) in comparison to offshore stations (~0.3), likely reflecting continental input from the shelf sediments. Compared to North Pacific Deep Water (Alibo and Nozaki, 1999) the shelf samples are depleted in REEs, except for La and Ce, revealing that in addition to shelf inputs and dissolution of lithogenic particles, particle scavenging processes in the highly productive shelf area exert a major control on the REE concentrations. Interestingly there is no clear correlation between oxygen concentration and the Ce anomaly (Ce*) as in waters with oxygen concentrations below 5 μmol/kg the Ce* ranged between 0.2 and 1.0. References: Hathorne, E. C., Haley, B., Stichel, T., Grasse, P., Zieringer, M., & Frank, M. (2012). Online preconcentration ICP-MS analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in seawater. <span class="hlt">Geochemistry</span> Geophysics Geosystems, 13(1), 1-12. doi:10.1029/2011GC003907 Alibo, D. S., & Nozaki, Y. (1999). Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in seawater: Particle association, shale-normalization, and Ce oxidation. Geochimica et Cosmochimica Acta, 63(3/4), 363-372.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E.102A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E.102A"><span id="translatedtitle"><span class="hlt">Elemental</span> processes of transport and energy conversion in <span class="hlt">Earth</span>'s magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Angelopoulos, Vassilis</p> <p></p> <p>In the last 5 years observations from several missions and ground based observatories have honed in on the most <span class="hlt">elemental</span> aspects of flux transport and energy conversion. Dipolarization fronts and their counterpart in the distant magnetotail "anti-dipolarization" fronts, which together are refered to herein as "reconnection fronts", usher the recently reconnected flux tubes from the near-<span class="hlt">Earth</span> X-points and in the process convert magnetic energy to particle energy and wave radiation. On the tailward side they are responsible for plasmoid formation and acceleration. On the earthward side they result in <span class="hlt">elemental</span> substorm current wedges or wedglets, which were initially postulated from ground observations alone. Recent observations have revealed how the interaction of wedgelets and the inner magnetosphere takes place. Questions remain with regards to the physics of the energy transfer process from global magnetic energy to local heating and waves, and with regards to the initiation of the X-point activations in space. Observations indicate that the latter may be induced by polar cap or dayside activity, suggesting a direct link between dayside reconnection and nightside phenomena. The likely causal sequence of events and open questions in light of these recent observations, and the field's outlook in anticipation of upcoming coordinated observations from the international Heliophysics System Observatory will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6141815','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6141815"><span id="translatedtitle">Reducing the detection limits of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in steels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Raskevich, V.K.; Maiboroda, I.K.; Frishberg, A.A.; Panfilova, S.Ya.</p> <p>1986-12-01</p> <p>Chemical and chemicospectral analysis methods make it possible to determine rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) reliably in steels, but they are time-consuming and laborious. X-ray fluorescence methods are also characterized by the complicated procedure of preparing standard and production specimens for analysis. In this paper, the authors attempt to develop a spectrographic method of determining the REEs in the steel using standard equipment. The authors prepare synthetic standard specimens for determining Ce, Nd, La, Pr, and Y in steels of various grades by adding titrated solutions of the salts of the determined <span class="hlt">elements</span> to the powder of the steel without REE with subsequent evaporation, drying, and mixing. The steels were ground by the mechanical method. On the basis of the resulting detection limits and analysis accuracy, the proposed method can be recommended for inspection of the technological process in melting steels and for preparation of standard specimens in the plant. The method is 5-7 times faster than the chemicospectral method.</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 id="translatedtitle">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/2012PCE....50...52M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PCE....50...52M"><span id="translatedtitle">Minor <span class="hlt">element</span> <span class="hlt">geochemistry</span> of groundwater from an area with prevailing saline groundwater in Chikhwawa, lower Shire valley (Malawi)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Monjerezi, Maurice; Vogt, Rolf D.; Gebru, Asfaw Gebretsadik; Saka, John D. K.; Aagaard, Per</p> <p></p> <p>Groundwater resources with high salinity content are found in some parts of the lower Shire River valley (Malawi). This paper discusses the <span class="hlt">geochemistry</span> of minor <span class="hlt">elements</span> with regards to the prevailing salinity. Hierarchical clustering and principal component analyses were used to identify factors which relate to both minor <span class="hlt">elements</span> and samples and were interpreted as reflecting the influence of prevailing saline/brackish groundwater. Concentrations of lead (Pb), boron (B), strontium (Sr) and chromium (Cr) were associated with groundwater with high content of total dissolved solids (TDS). Speciation calculations indicated that dissolved Sr, barium (Ba) and lithium (Li) were mainly in the form of free aqueous ions whereas hydrolysed species were significant for aluminium (Al) and Cr, and carbonate complexes for Pb. Chloride complexes were prevalent for silver (Ag). Solubility of cerussite (PbCO3) and barite (BaSO4) was shown to act as a control on the levels of Pb and Ba, respectively. Thus, Ba concentrations were very low in saline groundwater owing to their high sulphate content. A relatively variable B concentration in the groundwater samples was explained using a binary mixing model of saline and fresh groundwater. The mixing of fresh groundwater with saline groundwater was concomitant with high Na+/Ca2+ ratios and enrichment of B, probably by desorption from clays. The WHO drinking water guidelines for Ba, B, Cr and Pb were exceeded in 6.5%, 9.7%, 16.1% and 64.5% of all the samples, respectively. However, all samples were below the Malawian specification of B in borehole and shallow well water quality (MS 733:2005) of 5.0 mg/L.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.7084C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.7084C&link_type=ABSTRACT"><span id="translatedtitle">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/2003EAEJA....12878C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....12878C"><span id="translatedtitle">A comparative study of the particulate trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> in two contrasting ocean margin environments in the Northeastern Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chou, L.; Wollast, R.; Roevros, N.</p> <p>2003-04-01</p> <p>The present study was conducted during the Phases I and II of the Ocean Margin EXchange (OMEX) project, supported by the European Union in the framework of the MAST programme. The objective was to characterise the suspended matter by its composition with emphasis on trace <span class="hlt">elements</span> in order to evaluate the sources, biogeochemical behaviour in the water column and fate of particulate material in two contrasting ocean margin environments: the Biscay margin and the Iberian margin. The Biscay margin is bordered by a wide continental plateau and a steep continental slope and rise, and is characterised by strong internal tides among many other physical processes with limited riverine input. In contrast, the Iberian margin is characterised by a narrow continental plateau receiving regularly continental input and by seasonal upwelling/downwelling that could influence significantly the chemical composition, transport and fluxes of particles in this region. Suspended matter in the water column along the two margins was sampled by various methods. These include 1) continuous centrifugation of surface waters, 2) in-situ filtration of large volumes of water at various depths using Stand Alone Pumps (SAPs), and 3) sediment traps. In addition to trace <span class="hlt">elements</span> (Cr, Co, Ni, Cu, Zn Cd, Pb), the chemical composition of particulate matter collected was determined for major (Si, Al, Fe, Ca, POC/PN) and minor (Mg, Na, K, Mn) <span class="hlt">elements</span>. Centrifugation samples allow the determination of the composition of surface suspended matter dominated by phytoplankton. SAP samples permit the assessment of the vertical evolution of suspended matter composition in the water column. Settling material intercepted by the sediment traps, are associated with large particles such as faecal pellets, marine snow and other aggregates. Trace metal <span class="hlt">geochemistry</span> of the particulate matter in relation to the carbon cycle will be compared in the two margin environments investigated. Processes affecting the transfer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.258....1A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.258....1A&link_type=ABSTRACT"><span id="translatedtitle">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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFMEP13B0949I&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFMEP13B0949I&link_type=ABSTRACT"><span id="translatedtitle">Isotopic fractionation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in geochemical samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishibashi, T.; Ohno, T.</p> <p>2015-12-01</p> <p>The isotopic composition of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span>(REEs) can be fractionated through various physical and chemical reactions in nature [1]. The isotopic variations of REEs occurring naturally has a potentially significant influence in geochemical research fields. The REEs has key features that their chemical similarities and gradual changes of ionic radius, which may help us to understand the mechanisms of isotopic variations of REEs in nature. Among the REEs, geochemical and physicochemical features of Ce, which could be presence as the tetravalent state, be anomalous, and oxidation state of Ce can change by reflecting the redox conditions of the environment. Therefore, the study of the difference in the degree of isotopic fractionation between Ce and other REEs may provide information on the redox conditions. In this study, we developed a new separation method to determine the mass-dependent isotopic fractionations of REEs in geochemical samples, and examined the optimum concentration of hydrochloric acid for the separation. The samples were decomposed by a mixture of acids, then REEs were separated as a group from major <span class="hlt">elements</span> using cation exchange resin columns and RE Spec resin. The separations within the REEs group were carried out using Ln2Spec resin. For the recovery of La, Ce, Pr, and Nd, 0.1 M HCl was used, and for isolation of Sm, Eu, and Gd, 0.25 M HCl was used. Then, 0.6 M HCl was used for separation of Tb, and Dy, 1 M HCl was used for separation of Ho, Y, and Er, finally, Tm, Yb, and Lu were collected using 2 M HCl. The yields of all REEs were enough to examine isotopic fractionation in geochemical samples. [1] Ohno and Hirata,Analytical Sciences, 29, 271, 2013</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 id="translatedtitle">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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..16.5328M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..16.5328M&link_type=ABSTRACT"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/14582968','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/14582968"><span id="translatedtitle">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="http://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>2003-11-01</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. PMID:14582968</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6579398','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6579398"><span id="translatedtitle">Trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of gradient hole cuttings: Beowawe geothermal area, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Christensen, O.D.</p> <p>1980-12-01</p> <p>Multielement geochemical analysis of drill cuttings from 26 shallow temperature-gradient drill holes and of surface rock samples reveals trace <span class="hlt">element</span> distributions developed within these rocks as a consequence of chemical interaction with thermal fluid within the Beowawe geothermal area. The presently discharging thermal fluids are dilute in all components except silica, suggesting that the residence time of these fluids within the thermal reservoir has been short and that chemical interaction with the reservoir rock minimal. Interaction between these dilute fluids and rocks within the system has resulted in the development of weak chemical signatures. The absence of stronger signatures in rocks associated with the present system suggests that fluids have had a similar dilute chemistry for some time. The spatial distribution of <span class="hlt">elements</span> commonly associated with geothermal systems, such as As, Hg and Li, and neither laterally nor vertically continuous. This suggests that there is not now, nor has there been in the past, pervasive movement of thermal fluid throughout the sampled rock but, instead, that isolated chemical anomalies represent distinct fluid-flow chanels. Discontinuous As, Li and Hg concentrations near White Canyon to the east of the presently active surface features record the effects of chemical interaction of rocks with fluids chemically unlike the presently discharging fluids. The observed trace <span class="hlt">element</span> distributions suggest that historically the Beowawe area has been the center of more than one hydrothermal event and that the near-surface portion of the present hot-water geothermal system is controlled by a single source fracture, the Malpais Fault, or an intersection of faults at the sinter terrace.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MAR.T1273C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MAR.T1273C"><span id="translatedtitle">Rare-<span class="hlt">earth</span> <span class="hlt">element</span> based permanent magnets: a theoretical investigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chouhan, Rajiv K.; Paudyal, Durga</p> <p></p> <p>Permanent magnetic materials with large magnetization and high magnetocrystalline anisotropy are important for technical applications. In this context rare-<span class="hlt">earth</span> (R) <span class="hlt">element</span> based materials are good candidates because of their localized 4 f electrons. The 4 f crystal field splitting provides large part of magnetic anisotropy depending upon the crystal environment. The d spin orbit coupling of alloyed transition metal component provides additional anisotropy. RCo5 and its derivative R2Co17 are known compounds for large magnetic anisotropy. Here we have performed electronic structure calculations to predict new materials in this class by employing site substitutions. In these investigations, we have performed density functional theory including on-site electron correlation (DFT +U) and L-S coupling calculations. The results show that the abundant Ce substitution in R sites and Ti/Zr substitutions in some of the Co sites help reduce criticality without substantially affecting the magnetic moment and magnetic anisotropy in these materials. This work is supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.</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 id="translatedtitle">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://www.osti.gov/scitech/biblio/21176850','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21176850"><span id="translatedtitle">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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012GeCoA..83...79B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012GeCoA..83...79B&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of CI chondrites: Major and trace <span class="hlt">elements</span>, and Cu and Zn Isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barrat, J. A.; Zanda, B.; Moynier, F.; Bollinger, C.; Liorzou, C.; Bayon, G.</p> <p>2012-04-01</p> <p>In order to check the heterogeneity of the CI chondrites and determine the average composition of this group of meteorites, we analyzed a series of six large chips (weighing between 0.6 and 1.2 g) of Orgueil prepared from five different stones. In addition, one sample from each of Ivuna and Alais was analyzed. Although the sizes of the chips used in this study were “large”, our results show evidence for minor chemical heterogeneity in Orgueil, particularly for alkali <span class="hlt">elements</span> and U. After removal of one outlier sample, the spread of the results is considerably reduced. For most of the 46 <span class="hlt">elements</span> analyzed in this study, the average composition calculated for Orgueil is in very good agreement with previous CI estimates. This average, obtained with a “large” mass of samples, is analytically homogeneous and is suitable for normalization purposes. Finally, the Cu and Zn isotopic ratios are homogeneously distributed within the CI parent body with a spread of less than 100 ppm per atomic mass unit (amu).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5224579','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5224579"><span id="translatedtitle">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> </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://pubs.er.usgs.gov/publication/70016788','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016788"><span id="translatedtitle">Major <span class="hlt">element</span>, REE, and Pb, Nd and Sr isotopic <span class="hlt">geochemistry</span> of Cenozoic volcanic rocks of eastern China: implications for their origin from suboceanic-type mantle reservoirs</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Basu, A.R.; Wang, Junwen; Huang, Wankang; Xie, Guanghong; Tatsumoto, M.</p> <p>1991-01-01</p> <p>Major- and rare-<span class="hlt">earth-element</span> (REE) concentrations and UThPb, SmNd, and RbSr isotope systematics are reported for Cenozoic volcanic rocks from northeastern and eastern China. These volcanic rocks, characteristically lacking the calc-alkaline suite of orogenic belts, were emplaced in a rift system which formed in response to the subduction of the western Pacific plate beneath the eastern Asiatic continental margin. The rocks sampled range from basanite and alkali olivine basalt, through olivine tholeiite and quartz tholeiite, to potassic basalts, alkali trachytes, pantellerite, and limburgite. These rock suites represent the volcanic centers of Datong, Hanobar, Kuandian, Changbaishan and Wudalianchi in northeastern China, and Mingxi in the Fujian Province of eastern China. The major-<span class="hlt">element</span> and REE <span class="hlt">geochemistry</span> is characteristic of each volcanic suite broadly evolving through cogenetic magmatic processes. Some of the outstanding features of the isotopic correlation arrays are as follows: (1) NdSr shows an anticorrelation within the field of ocean island basalts, extending from the MORB end-member to an enriched, time-averaged high Rb Sr and Nd Sr end-member (EM1), (2) SrPb also shows an anticorrelation, similar to that of Hawaiian and walvis Ridge basalts, (3) NdPb shows a positive correlation, and (4) the 207Pb 204Pb vs 206Pb 204Pb plot shows linear arrays parallel to the general trend (NHRL) for MORB on both sides of the geochron, although in the 208Pb 204Pb vs 206Pb 204Pb plot the linear array is significantly displaced above the NHRL in a pattern similar to that of the oceanic island basalts that show the Dupal signatures. In all isotope correlation patterns, the data arrays define two different mantle components-a MORB-like component and an enriched mantle component. The isotopic data presented here clearly demonstrate the existence of Dupal compositions in the sources of the continental volcanic rocks of eastern China. We suggest that the subcontinental mantle</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/ofr20071047SRP078','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/ofr20071047SRP078"><span id="translatedtitle">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://pubs.er.usgs.gov/publication/70013127','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013127"><span id="translatedtitle">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 id="translatedtitle">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://adsabs.harvard.edu/abs/2014JAfES.100..335M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAfES.100..335M"><span id="translatedtitle">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 id="translatedtitle">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/2011AGUFM.V22C..07P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V22C..07P"><span id="translatedtitle">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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFM.V54A..02H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFM.V54A..02H&link_type=ABSTRACT"><span id="translatedtitle">Deciphering The Sources Of Cenozoic Volcanism In Central Mongolia Using Trace <span class="hlt">Element</span> And Isotope <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>Hunt, A. C.; Parkinson, I. J.; Harris, N.; Rogers, N. W.; Barry, T.; Yondon, M.</p> <p>2009-12-01</p> <p>One of the largest regions of Cenozoic intra-plate volcanism stretches across central Asia from the Baikal Rift in Siberia, through central Mongolia to China. In Mongolia this is expressed as numerous small-volume alkali-basaltic cones and lavas, erupted since ca. 30 Ma. Currently, accepted models of melt generation for intraplate magmatism, such as mantle plumes, lithospheric extension and convective removal of the lithosphere, are difficult to reconcile with some aspects of volcanism and tectonics in this region. A suite of basalts erupted across an area of Cenozoic uplift in central Mongolia, known as the Hangai Dome, has been analysed for trace <span class="hlt">elements</span> and Sr-Nd-Pb isotopes. New Pb isotope data were collected by double spike MC-ICP-MS at the Open University and have a long-term 2σ reproducibility better than 175 ppm for NBS 981. These data suggest progressive mixing between two distinct source regions in the genesis of the Hangai basalts. Older basalts, previously dated at 5.91 ± 0.02 Ma (Barry et al., 2003), are derived from a component with an asthenospheric signature similar to depleted Indian MORB. Younger basalts are increasingly mixed with a component with lower Pb and Sr ratios and an enriched trace <span class="hlt">element</span> signature, which is similar in composition to some lamproites erupted in the western USA (Mirnejad and Bell, 2006). This represents a transition from asthenospheric to lithospheric melting through time. Furthermore, studies on mantle xenoliths from across the Hangai Dome indicate an elevated geotherm under the centre of the dome and significantly cooler conditions at its margins, interpreted to be the result of mantle upwellling (Harris et al., in review). Further numerical modelling will assess the relative contributions from lithospheric and asthenospheric sources in the genesis of these basalts, and contribute to understanding this enigmatic volcanic region. Barry, T. L., Saunders, A. D., Kempton, P. D., Windley, B.F., Pringle, M.S., Dorjnamjaa</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 id="translatedtitle">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/2013AGUFM.V53E..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V53E..02P"><span id="translatedtitle">Elucidating the construction of the Austurhorn Intrusion, SE 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.; Fisher, C. M.; Hanchar, J. M.; Bindeman, I. N.; Wooden, J. L.; Sigmarsson, O.</p> <p>2013-12-01</p> <p>The Austurhorn Intrusive Complex (AIC) in SE Iceland comprises large bodies of granophyre, gabbro, and a mafic-felsic composite zone (MFCZ) that exemplifies mafic-felsic interactions common in Icelandic silicic systems. However, despite being one of Iceland's best-studied intrusions (Blake 1966; Furman et al 1992a,b; Thorarinsson & Tegner 2009), 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 in-situ zircon <span class="hlt">elemental</span> and isotopic (hafnium and oxygen) <span class="hlt">geochemistry</span>, as well as U-Pb geochronology, as tools for elucidating the complex construction and magmatic evolution of Austurhorn's MFCZ. The <span class="hlt">elemental</span> compositions of AIC zircons form a broad but coherent array partly overlapping with the zircon geochemical signature for Icelandic silicic volcanic rocks (Carley et al 2011). With some exceptions (see below), Hf concentrations are low (less than 10,000 ppm), typical of Icelandic zircon, and Ti concentrations range from 6 to 25 ppm (Ti-in-zircon temps. 730-870°C). Their δ18O values are generally well-constrained at +2.5 to +4 ‰, consistent with other Icelandic magmatic zircon (Bindeman et al 2012) and preserving evidence for partial melting of hydrothermally-altered crust as the source of silicic magmas within the Austurhorn system. Epsilon-Hf values cluster tightly at +13×1 ɛ-units, suggesting a single source for the different units of the MFCZ. The notable exceptions to the trends described above are zircons from a high-silica granophyre displaying CL-dark zones and convoluted zoning. These fall well outside the AIC geochemical arrays, primarily distinguished by high Hf (up to 24,000 ppm) and lower Ti (down to 2 ppm), far higher Hf and lower Ti than any other analyzed Icelandic zircon, and extremely low δ18O values (down to -6 ‰). We interpret these to reflect multiple episodes of partial melting and melt extraction of the</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 id="translatedtitle"><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://adsabs.harvard.edu/abs/2014AGUFM.B11C0036Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B11C0036Y"><span id="translatedtitle">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('http://www.osti.gov/scitech/biblio/6673547','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6673547"><span id="translatedtitle">Trace <span class="hlt">element</span> and REE <span class="hlt">geochemistry</span> of Red Butte, Oregon: a gold-bearing hot spring system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Evans, C.S.; Cummings, M.L.</p> <p>1985-01-01</p> <p>Red Butte, 60 km south of Vale, Oregon is an Au-bearing hot spring deposit of intercalated lacustrine and fluvial Mio-Pliocene volcaniclastic sediments and basalt flows. Topography of the butte is controlled by a 30-60 m thick cap of silicified sediments which is cut by N and NW-trending faults. Anomalous Au, As, Sb, and Hg occur in fault controlled quartz veins, quartz-adularia veins, silicified sediments and rarely in calcite-quartz veins cutting basalt. Distribution of these <span class="hlt">elements</span> away from the veins is controlled by permeability of the host rock. REE concentrations were normalized to chondritic abundances for 73 sediment, basalt, and vein samples. Silicified sediments from the butte top and unsilicified sediments from the east slope of the butte have similar LREE enriched patterns with strong negative Eu anomalies reflecting their felsic volcanic source. Silicified sediments are depleted in all REEs relative to fresh sediments indicating dilution by silica deposition. Basalt REE patterns are much closer to chondritic ratios. Patterns of veined basalt mirror those for fresh basalts but are relatively depleted in all REEs. Quartz-adularia and quartz veins have REE abundances 2-3 orders of magnitude lower than fresh sediments, and REE patterns unlike either the sediments or basalts. Mobility of REEs in the hydrothermal fluid is seen in La/Sm and Sa/Yb ratios of the veins. The La/Sm ratio for sediments averages 3.70. In veins this ratio drops to 1.65. The average La/Yb ratio is 9.1 in sediments and falls to 1.65 in quartz veins. Fluids depositing quartz and adularia in veins carried REEs in low abundance and deposited them in ratios that do not reflect the host rock. Any movement of REEs in host rock may have been masked by original high REE content combined with silica dilution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005GeCoA..69.2095C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005GeCoA..69.2095C"><span id="translatedtitle">Trace <span class="hlt">element</span> cycling in a subterranean estuary: Part 1. <span class="hlt">Geochemistry</span> of the permeable sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Charette, Matthew A.; Sholkovitz, Edward R.; Hansel, Colleen M.</p> <p>2005-04-01</p> <p>Subterranean estuaries are characterized by the mixing of terrestrially derived groundwater and seawater in a coastal aquifer. Subterranean estuaries, like their river water-seawater counterparts on the surface of the <span class="hlt">earth</span>, represent a major, but less visible, hydrological and geochemical interface between the continents and the ocean. This article is the first in a two-part series on the biogeochemistry of the subterranean estuary at the head of Waquoit Bay (Cape Cod, MA, USA). The pore-water distributions of salinity, Fe and Mn establish the salt and redox framework of this subterranean estuary. The biogeochemistry of Fe, Mn, P, Ba, U and Th will be addressed from the perspective of the sediment composition. A second article will focus on the groundwater and pore-water chemistries of Fe, Mn, U and Ba. Three sediment cores were collected from the head of Waquoit Bay where the coastal aquifer consists of permeable sandy sediment. A selective dissolution method was used to measure the concentrations of P, Ba, U and Th that are associated with "amorphous (hydr)oxides of iron and manganese" and "crystalline Fe and Mn (hydr)oxides." The deeper sections of the cores are characterized by large amounts of iron (hydr)oxides that are precipitated onto organic C-poor quartz sand from high-salinity pore waters rich in dissolved ferrous iron. Unlike Fe (hydr)oxides, which increase with depth, the Mn (hydr)oxides display midcore maxima. This type of vertical stratification is consistent with redox-controlled diagenesis in which Mn (hydr)oxides are formed at shallower depths than iron (hydr)oxides. P and Th are enriched in the deep sections of the cores, consistent with their well-documented affinity for Fe (hydr)oxides. In contrast, the downcore distribution of Ba, especially in core 3, more closely tracks the concentration of Mn (hydr)oxides. Even though Mn (hydr)oxides are 200-300 times less abundant than Fe (hydr)oxides in the cores, Mn (hydr)oxides are known to have an</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 id="translatedtitle">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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4260943','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4260943"><span id="translatedtitle">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://pubs.usgs.gov/of/2011/1256/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/2011/1256/"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2010AGUFMPP11A1413M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMPP11A1413M"><span id="translatedtitle">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 id="translatedtitle">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('http://hdl.handle.net/2060/20120001844','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120001844"><span id="translatedtitle">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> </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/2013AGUSM.B41A..02R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSM.B41A..02R"><span id="translatedtitle">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/2014GeCoA.140...20C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.140...20C"><span id="translatedtitle">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/2013GeCoA.115...46G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.115...46G"><span id="translatedtitle">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 id="translatedtitle">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 id="translatedtitle">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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016E%26PSL.435..136W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016E%26PSL.435..136W&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Earth</span>'s moderately volatile <span class="hlt">element</span> composition may not be chondritic: Evidence from In, Cd and Zn</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zaicong; Laurenz, Vera; Petitgirard, Sylvain; Becker, Harry</p> <p>2016-02-01</p> <p>Current models assume that siderophile volatile <span class="hlt">elements</span> (SVE) are depleted in bulk <span class="hlt">Earth</span> to the same extent as lithophile <span class="hlt">elements</span> of similar volatility. The observed additional depletion of many SVE relative to lithophile <span class="hlt">elements</span> in the bulk silicate <span class="hlt">Earth</span> (BSE) is ascribed to partitioning of SVE into <span class="hlt">Earth</span>'s core. However, the assumption of similar volatility of moderately volatile <span class="hlt">elements</span> during <span class="hlt">Earth</span> formation processes as in solar gas is quite uncertain. Here, these assumptions will be tested by assessing abundances and ratios of indium and cadmium in the BSE using new data on mantle rocks, and the application of high- and low-pressure-temperature metal-silicate partitioning data. New bulk rock abundance data of In and Cd obtained on bulk rocks of peridotite tectonites and xenoliths by isotope dilution refine previous results inferred from basalts and in-situ analyses of silicate minerals in peridotite xenoliths. The CI chondrite-normalized abundance of In in the BSE is similar to zinc and is 3-4 times higher than Cd. New and published low- and high-P-T metal-silicate partitioning data indicate that, during core formation at a range of conditions, In is always more siderophile than Zn and Cd. Adding the fraction of these <span class="hlt">elements</span> in <span class="hlt">Earth</span>'s core to the BSE results in bulk <span class="hlt">Earth</span> compositions that yield higher CI chondrite normalized abundances of In in the bulk <span class="hlt">Earth</span> compared to Zn and Cd. Because In is more volatile than Zn and Cd in gas of solar composition, suprachondritic In/Zn and In/Cd in the bulk <span class="hlt">Earth</span> suggest that during formation of <span class="hlt">Earth</span> or its building materials, the volatilities of these <span class="hlt">elements</span> and perhaps other volatile <span class="hlt">elements</span> likely have changed significantly (i.e. In became less volatile). The results also suggest that known carbonaceous chondrites likely did not deliver the main volatile <span class="hlt">element</span>-rich fraction of the <span class="hlt">Earth</span>. Various arguments suggest that the loss of moderately volatile <span class="hlt">elements</span> during planetary accretion should be limited</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=251706&keyword=mining+AND+environment&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=77956600&CFTOKEN=15333029','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=251706&keyword=mining+AND+environment&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=77956600&CFTOKEN=15333029"><span id="translatedtitle">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://www.osti.gov/scitech/biblio/21062438','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21062438"><span id="translatedtitle">Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span>: A Tool for Understanding the Behaviour of Trivalent Actinides in the Geosphere</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buil, Belen; Gomez, Paloma; Garralon, Antonio; Turrero, M. Jesus</p> <p>2007-07-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations have been determined in groundwaters, granite and fracture fillings in a restored uranium mine. The granitoids normalized REE patterns of groundwaters show heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> (HREE)-enrichment and positive Eu anomalies. This suggests that the REE are fractionated during leaching from the source rocks by groundwaters. Preferential leaching of HREE would be consistent with the greater stability of their aqueous complexes compared to those of the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE), together with the dissolution of certain fracture filling minerals, dissolution/alteration of phyllosilicates and colloidal transport. (authors)</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 id="translatedtitle">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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005GGG.....6.7004K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005GGG.....6.7004K"><span id="translatedtitle">Major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and Os isotopic composition of metalliferous umbers from the Late Cretaceous Japanese accretionary complex</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; Suzuki, Katsuhiko</p> <p>2005-07-01</p> <p>Metalliferous umbers and red shales occur as unique products of the Kula-Pacific ridge-forearc collision in the Late Cretaceous Shimanto Supergroup, an accretionary complex in Japan. These umbers are closely associated with greenstones of mid-ocean ridge basalt (MORB) origin and are regarded as hydrothermal metalliferous precipitates related to MOR-type volcanism. The umbers and red shales were deposited in the trench area where both terrigenous detritus from land and hydrothermal metalliferous particulates from a MOR were supplied simultaneously. Besides a predominance of Fe and Mn, the umbers exhibit remarkable enrichments in P, V, Co, Ni, Zn, Y, Mo, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), and Os relative to continental crustal abundances. The X/Fe (X = Mn, P, V, Co, Ni, Zn, Y, and REEs) ratios and PAAS-normalized REE patterns of the umbers are very similar to those of modern hydrothermal plume fallout precipitates deposited on flanks of MOR. This indicates that the umbers preserve primary geochemical signatures of hydrothermal metalliferous sediments that scavenged seawater-derived <span class="hlt">elements</span> and thus can be used as a proxy for Late Cretaceous seawater. The marine 187Os/188Os ratios reconstructed from the late Maastrichtian umbers range from 0.42 to 0.56 and are very consistent with recent data obtained from the Pacific and Atlantic pelagic carbonates that record an abrupt decline from 0.55 to 0.4 during the period between 67.0 Ma and 65.7 Ma.</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 id="translatedtitle">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://hdl.handle.net/2060/19980002855','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980002855"><span id="translatedtitle">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 id="translatedtitle">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/cgi-bin/nph-data_query?bibcode=2016IJEaS.tmp...40L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016IJEaS.tmp...40L&link_type=ABSTRACT"><span id="translatedtitle"><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://www.osti.gov/scitech/biblio/5797291','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5797291"><span id="translatedtitle">Fluorescent lifetime measurements of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in gallium arsenide. Master's thesis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Topp, D.J.</p> <p>1990-12-01</p> <p>Lifetime measurements of the excited states of three GaAs semiconductors doped with the rare <span class="hlt">earth</span> <span class="hlt">elements</span> Erbium (Er), Praseodymium (Pr), and Thulium (Tm) has been studied using a pulsed nitrogen laser and germanium detector. The measurements were made with an experimental set up with a system response time of 0.34 microseconds. A 330 milliwatt nitrogen laser with a wavelength of 3370 angstroms was used to excite transitions of the rare <span class="hlt">earth</span> <span class="hlt">elements</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1261978','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1261978"><span id="translatedtitle">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/dataexplorer">DOE Data Explorer</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://adsabs.harvard.edu/abs/2015JAESc.105..300S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAESc.105..300S"><span id="translatedtitle">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('http://www.osti.gov/scitech/biblio/4836837','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/4836837"><span id="translatedtitle">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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1818375R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1818375R&link_type=ABSTRACT"><span id="translatedtitle">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/1984gord.book.....H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984gord.book.....H"><span id="translatedtitle"><span class="hlt">Geochemistry</span> and origin of regional dolomites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hanson, G. N.</p> <p></p> <p>Quantitative, geochemical models for the source, flow paths and chemistry of the diagnetic fluids responsible for the widespread dolomitization of the Mississippi Burlington-Keokuk Fms were developed. Iowa, Illinois and Missouri by integrating <span class="hlt">geochemistry</span>, fluid inclusion studies, conventional and luminescent petrography, stratigraphy, facies analysis and burial history. The study includes western Illinois and eastern Missouri and southeastern Iowa. This includes most of the area where good sections of facies from near shore to the platform edge. The geochemical studies include: correlation of the major and trace <span class="hlt">element</span> variations within the various Burlington dolomites developed in southeastern Iowa and adjacent areas of Illinois and Missouri; rare <span class="hlt">earth</span> <span class="hlt">element</span>, Nd and Sr isotope analysis of the dolomites and coexisting phases; major and trace <span class="hlt">element</span> analysis, petrography and X ray mineralogy of selected shaly members in the Burlington-Keokuk formations; and fluid inclusion studies of the calcites and dolomite cements of southeastern Iowa.</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://www.ncbi.nlm.nih.gov/pubmed/25089667','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25089667"><span id="translatedtitle">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="http://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. PMID:25089667</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005GeCoA..69.1607P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005GeCoA..69.1607P&link_type=ABSTRACT"><span id="translatedtitle">Highly siderophile <span class="hlt">element</span> <span class="hlt">geochemistry</span> of 187Os-enriched 2.8 Ga Kostomuksha komatiites, Baltic Shield</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Puchtel, Igor S.; Humayun, Munir</p> <p>2005-03-01</p> <p> composition of the <span class="hlt">Earth</span>'s mantle. The absolute HSE abundances in the source of the Kostomuksha komatiite have been demonstrated to be comparable to those of the source of Abitibi komatiites, even though the two komatiites contrast in their Os isotopic compositions. This supports the earlier hypothesis that if core-mantle interaction produced the 187Os/ 188Os radiogenic signature in the Kostomuksha source, it must have occurred in the form of isotope exchange at the core-mantle boundary. Other explanations of the radiogenic Os signature are similarly constrained to conserve the <span class="hlt">elemental</span> abundance pattern in the mantle source of Kostomuksha komatiites.</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 id="translatedtitle">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('http://www.ncbi.nlm.nih.gov/pubmed/24835593','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24835593"><span id="translatedtitle">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="http://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)). PMID:24835593</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAfES.114..220R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAfES.114..220R"><span id="translatedtitle">Scheelite geochemical signatures by LA-ICP-MS and potential for rare <span class="hlt">earth</span> <span class="hlt">elements</span> from Hutti Gold Mines and fingerprinting ore deposits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raju, P. V. S.; Hart, Craig J. R.; Sangurmath, P.</p> <p>2016-02-01</p> <p>Scheelite (CaWO4), with gold and REE enrichments, is found in appreciable concentrations in the world class Hutti Gold deposit, Eastern Dharwar Craton (EDC), India. We used in situ Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) to determine the rare <span class="hlt">earth</span> <span class="hlt">elements</span> in scheelite and utilize results to fingerprint the extensions/continuity of auriferous ore shoots/lodes/reefs. The Hutti Gold deposit is briefly compared to southern African gold deposits and corroborates in terms of <span class="hlt">geochemistry</span>, structural, chemical alterations and REE contents in scheelite etc… The scheelite samples from Hutti are enriched in light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE) up to 11 ppm and depleted in heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span>(HREE) up to 6.50 ppm with positive to negative europium anomaly. The total REE (∑ REE + Y) of the scheelite samples is up to 35 ppm. The ratio of LREE/HREE values is 1.80. The results for the REEs indicate: (1) considerable differences in the ΣREEs amongst the sample suite (2) most samples are dominated by a single chondrite-normalized (CN) pattern, but rarely a second pattern is present; 3) although the type of CN REE patterns vary (e.g., convex MREE, LREE enrichment), there is a similarity among deposit types; and 4) both positive and negative 'Eu' anomalies are observed; 5) positive correlations between MREE and HREE suggesting a strong influence of magmatic fluids. These initial results suggest that the minor and trace-<span class="hlt">element</span> chemistry of scheelite may offer the potential to discriminate and identify deposit types based on its geochemical fingerprinting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6292388','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6292388"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2003AGUFM.V51D0316P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.V51D0316P"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/26978935','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26978935"><span id="translatedtitle">[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="http://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. PMID:26978935</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/12663949','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/12663949"><span id="translatedtitle">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="http://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. PMID:12663949</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26676537','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26676537"><span id="translatedtitle">Molecular Polyarsenides of the 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=pubmed">PubMed</a></p> <p>Arleth, Nicholas; Gamer, Michael T; Köppe, Ralf; Konchenko, Sergey N; Fleischmann, Martin; Scheer, Manfred; Roesky, Peter W</p> <p>2016-01-22</p> <p>Reduction of [Cp*Fe(η(5)-As5)] with [Cp''2Sm(thf)] (Cp''=η(5)-1,3-(tBu)2C5H3) under various conditions led to [(Cp''2Sm)(μ,η(4):η(4)-As4)(Cp*Fe)] and [(Cp''2Sm)2As7(Cp*Fe)]. Both compounds are the first polyarsenides of the rare-<span class="hlt">earth</span> metals. [(Cp''2Sm)(μ,η(4):η(4)-As4)(Cp*Fe)] is also the first d/f-triple decker sandwich complex with a purely inorganic planar middle deck. The central As4(2-) unit is isolobal with the 6π-aromatic cyclobutadiene dianion (CH)4(2-). [(Cp''2Sm)2As7(Cp*Fe)] contains an As7(3-) cage, which has a norbornadiene-like structure with two short As-As bonds in the scaffold. DFT calculations confirm all the structural observations. The As-As bond order inside the cyclo As4 ligand in [(Cp''2Sm)(μ,η(4):η(4)-As4)(Cp*Fe)] was estimated to be in between an As-As single bond and a formally aromatic As4(2-) system. PMID:26676537</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMPP41A2051E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMPP41A2051E"><span id="translatedtitle">Effects of Drake Passage widening during the Eocene-Oligocene Transition on Southern Ocean bulk sediment 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>Elsworth, G.; Galbraith, E. D.; Halverson, G. P.</p> <p>2013-12-01</p> <p>Presently, the Southern Ocean provides three-quarters of the global nutrient supply to the low latitude surface ocean (Sarmiento et al. 2004; Palter et al. 2010). In this region the removal of nutrients by sinking organic matter is exceeded by wind-driven upwelling of remineralized nutrients along the Antarctic Circumpolar Current (ACC). The excess nutrients are then advected across the ACC into Subantarctic Mode Water (SAMW), a water mass that transfers the unutilized Southern Ocean nutrients to low-latitude upwelling regions (Toggweiler et al. 1991). However, prior to the opening of the Drake Passage near the Eocene-Oligocene Transition (EOT) the ACC did not exist, suggesting a change in nutrient dynamics of the Southern Ocean. <span class="hlt">Earth</span> system model simulations by Yang et al. 2013 suggest that as the Drake Passage opened, the supply of southern nutrients would have increased, possibly amplifying iron limitation and increasing oxygenation of the deep Southern Ocean. These results indicate that different surface nutrient return pathways in the pre- and post-Drake Passage Southern Ocean may have changed nutrients available to phytoplankton. To assess geological records of these model predictions, Integrated Ocean Drilling Program (IODP) Sites 689 and 1090 have been sampled at 15 to 50 kyr intervals from 31 to 37 Ma. Site 689, located on Maud Rise in the Weddell Sea, and Site 1090, located on Agulhas Ridge in the Southern Atlantic, provide a crucial transect across the Atlantic Sector of the Southern Ocean to examine the influence of the developing ACC on ocean circulation. Bulk sediment trace <span class="hlt">element</span> analyses using inductively coupled plasma optical emission spectrometry (ICP OES) provide indications of biological surface export (Ca, Ba), deep-water oxygenation (U, Mo, Mn), and dust influx (Th, Rb). Results will be presented at the meeting.</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 id="translatedtitle">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('http://adsabs.harvard.edu/abs/2015AGUFM.V52A..05D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V52A..05D"><span id="translatedtitle">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/2012EOSTr..93..134S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93..134S"><span id="translatedtitle">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...tmp..314K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JOM...tmp..314K"><span id="translatedtitle">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>2014-09-01</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/2014JOM....66k2355K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JOM....66k2355K"><span id="translatedtitle">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/1993Metic..28Q.454W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Metic..28Q.454W"><span id="translatedtitle">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://eric.ed.gov/?q=geochemistry&pg=2&id=EJ276909','ERIC'); return false;" href="http://eric.ed.gov/?q=geochemistry&pg=2&id=EJ276909"><span id="translatedtitle">Exploration <span class="hlt">Geochemistry</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Closs, L. Graham</p> <p>1983-01-01</p> <p>Contributions in mineral-deposit model formulation, geochemical exploration in glaciated and arid environments, analytical and sampling problems, and bibliographic research were made in symposia held and proceedings volumes published during 1982. Highlights of these symposia and proceedings and comments on trends in exploration <span class="hlt">geochemistry</span> are…</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 id="translatedtitle">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('http://www.osti.gov/scitech/biblio/20076087','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20076087"><span id="translatedtitle">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> </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('http://ntrs.nasa.gov/search.jsp?R=19810057588&hterms=Tectonophysics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DTectonophysics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810057588&hterms=Tectonophysics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DTectonophysics"><span id="translatedtitle">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.ars.usda.gov/research/publications/Publications.htm?seq_no_115=234552','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=234552"><span id="translatedtitle">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://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=256482&keyword=importance+AND+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=76787444&CFTOKEN=53136575','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=256482&keyword=importance+AND+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=76787444&CFTOKEN=53136575"><span id="translatedtitle">A LOW-COST RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENTS</span> RECOVERY TECHNOLOGY - PHASE I</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><div> Physical Sciences, Inc., and the University of Kentucky Center for Applied Energy Research propose to develop a unique enabling technology to significantly reduce U.S. dependency for Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) on foreign suppliers and our global competitors. Our innovation...</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 id="translatedtitle">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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=250918','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=250918"><span id="translatedtitle">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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3458658','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3458658"><span id="translatedtitle">Undecaprenyl Pyrophosphate Involvement in Susceptibility of Bacillus subtilis to 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>Ochi, Kozo</p> <p>2012-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">element</span> scandium has weak antibacterial potency. We identified a mutation responsible for a scandium-resistant phenotype in Bacillus subtilis. This mutation was found within the uppS gene, which encodes undecaprenyl pyrophosphate synthase, and designated uppS86 (for the Thr-to-Ile amino acid substitution at residue 86 of undecaprenyl pyrophosphate synthase). The uppS86 mutation also gave rise to increased resistance to bacitracin, which prevents cell wall synthesis by inhibiting the dephosphorylation of undecaprenyl pyrophosphate, in addition to enhanced amylase production. Conversely, overexpression of the wild-type uppS gene resulted in increased susceptibilities to both scandium and bacitracin. Moreover, the mutant lacking undecaprenyl pyrophosphate phosphatase (BcrC) showed increased susceptibility to all rare <span class="hlt">earth</span> <span class="hlt">elements</span> tested. These results suggest that the accumulation of undecaprenyl pyrophosphate renders cells more susceptible to rare <span class="hlt">earth</span> <span class="hlt">elements</span>. The availability of undecaprenyl pyrophosphate may be an important determinant for susceptibility to rare <span class="hlt">earth</span> <span class="hlt">elements</span>, such as scandium. PMID:22904278</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=65248715&CFTOKEN=94981065','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=65248715&CFTOKEN=94981065"><span id="translatedtitle">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://adsabs.harvard.edu/abs/2014RJPCA..88.1281L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014RJPCA..88.1281L"><span id="translatedtitle">Studying the volatility of pyrazolone complexes of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> by means of Knudsen effusion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lazarev, N. M.; Petrov, B. I.; Bochkarev, L. N.; Safronova, A. V.; Abakumov, G. A.; Arapova, A. V.; Bessonova, Yu. A.</p> <p>2014-08-01</p> <p>The temperature dependences of the pressure of saturated vapor of pyrazolone complexes of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> Ln(PMIP)3 (where Ln = Y, Ho, Er, Tm, Lu; PMIP = 1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone) are studied via Knudsen effusion, and the enthalpy of their sublimation is determined. Mass spectra and differential scanning calorimetry data are obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1234403','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1234403"><span id="translatedtitle">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/dataexplorer">DOE Data Explorer</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-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1261977"><span id="translatedtitle">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/dataexplorer">DOE Data Explorer</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=47189&keyword=Neutron&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=63956839&CFTOKEN=94443889','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47189&keyword=Neutron&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=63956839&CFTOKEN=94443889"><span id="translatedtitle">SEDIMENT REWORKING AND TRANSPORT IN EASTERN LAKE SUPERIOR: IN SITU RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENT</span> TRACER STUDIES</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 rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) tracer pellet was deployed at the floor of the Ile Parisienne basin of eastern Lake Superior to measure representative sediment reworking and transport processes in the benthic boundary layer of the prnfundal Great Lakes. Samarium oxide, a high neutron-...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27482724','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27482724"><span id="translatedtitle">Catalytic Graphitization of Coal-Based Carbon Materials with Light 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=pubmed">PubMed</a></p> <p>Wang, Rongyan; Lu, Guimin; Qiao, Wenming; Yu, Jianguo</p> <p>2016-08-30</p> <p>The catalytic graphitization mechanism of coal-based carbon materials with light rare <span class="hlt">earth</span> <span class="hlt">elements</span> was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare <span class="hlt">earth</span> <span class="hlt">elements</span> and carbon materials was carefully observed, and two routes of rare <span class="hlt">earth</span> <span class="hlt">elements</span> catalyzing the carbon materials were found: dissolution-precipitation and carbide formation-decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare <span class="hlt">earth</span> <span class="hlt">elements</span> exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure. PMID:27482724</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1234401','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1234401"><span id="translatedtitle">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/dataexplorer">DOE Data Explorer</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://pubs.er.usgs.gov/publication/70030422','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030422"><span id="translatedtitle">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/1987GeCoA..51..901M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987GeCoA..51..901M"><span id="translatedtitle">Uranium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in CO 2-rich waters from Vals-les-Bains (France)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michard, Annie; Beaucaire, Catherine; Michard, Gil</p> <p>1987-04-01</p> <p>Waters from springs at Vals-les-Bains result from the mixing of a CO 2-rich, highly mineralized water with dilute, shallow subsurface water. Total content of dissolved species vary from 5 mmol/1 to 100 mmol/1. For many <span class="hlt">elements</span>, mixing of these waters is non-linear (non-conservative) and further water-rock reactions take place. The pH is controlled by CO 2 outgassing, redox conditions are controlled by both the iron hydroxide-siderite buffer and the introduction of oxygen with shallow subsurface waters. Among the major <span class="hlt">elements</span>, concentrations of Ca, Mg, Mn, Fe, are related to mixing, CO 2 outgassing and carbonate precipitation. Uranium shows a complex behaviour controlled by carbonate complexing, redox conditions, mixing of waters and leaching from the rocks. The 234U /238U activity ratio is near secular equilibrium. In the more dilute waters, dissolved rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns are almost flat with a slight negative Eu anomaly. In the concentrated waters, heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> (Gd-Yb, HREE) are strongly enriched relative to light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (Ce-Eu, LREE). We relate the enrichment in HREE to water chemistry and to complexing with carbonate species.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26739864','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26739864"><span id="translatedtitle">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="http://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. PMID:26739864</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 id="translatedtitle">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://www.osti.gov/scitech/biblio/21222359','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21222359"><span id="translatedtitle">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/cgi-bin/nph-data_query?bibcode=2014cosp...40E2641P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014cosp...40E2641P&link_type=ABSTRACT"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/23811462','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23811462"><span id="translatedtitle">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="http://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. PMID:23811462</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://ntrs.nasa.gov/search.jsp?R=19860044210&hterms=origin+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorigin%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860044210&hterms=origin+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorigin%2Bearth"><span id="translatedtitle">Origin of the <span class="hlt">earth</span>'s moon - Constraints from alkali volatile trace <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>Kreutzberger, M. E.; Drake, M. J.; Jones, J. H.</p> <p>1986-01-01</p> <p>Although the moon is depleted in volatile <span class="hlt">elements</span> compared to the <span class="hlt">earth</span>, these depletions are not in accord with simple volatility. For example, the Cs/Rb ratios of the <span class="hlt">earth</span> and moon inferred from basalt are approximately one seventh and one half of the CI ratio, respectively. Volatility considerations alone predict that the lunar Cs/Rb ratio should be equal to or lower than the terrestrial ratio if the moon was derived entirely from <span class="hlt">earth</span> mantle material. Thus hypotheses such as rotational fission which invoke derivation of lunar material entirely from the <span class="hlt">earth</span>'s mantle may be excluded. The collisional ejection hypothesis of lunar origin requires at least 18 percent of lunar material to be derived from a projectile with dehydrated CI composition to match the lunar Cs/Rb ratio, and 25-50 percent to match both the lunar Cs/Rb ratio and absolute concentrations of Cs and Rb. It remains to be demonstrated that this relatively large contribution of projectile material is consistent with other <span class="hlt">elemental</span> abundances and <span class="hlt">element</span> ratios in the moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAfES..90...64A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAfES..90...64A"><span id="translatedtitle">The provenance of Cretaceous to Quaternary sediments in the Tarfaya basin, SW Morocco: Evidence from trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and radiogenic Nd-Sr isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ali, Sajid; Stattegger, Karl; Garbe-Schönberg, Dieter; Frank, Martin; Kraft, Steffanie; Kuhnt, Wolfgang</p> <p>2014-02-01</p> <p>We present trace <span class="hlt">element</span> compositions, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and radiogenic Nd-Sr isotope analyses of Cretaceous to recent sediments of the Tarfaya basin, SW Morocco, in order to identify tectonic setting, source rocks composition and sediments provenance. The results suggest that the sediments originate from heterogeneous source areas of the Reguibat Shield and the Mauritanides (West African Craton), as well as the western Anti-Atlas, which probably form the basement in this area. For interpreting the analyzed trace <span class="hlt">element</span> results, we assume that <span class="hlt">elemental</span> ratios such as La/Sc, Th/Sc, Cr/Th, Th/Co, La/Co and Eu/Eu∗ in the detrital silicate fraction of the sedimentary rocks behaved as a closed system during transport and cementation, which is justified by the consistency of all obtained results. The La/Y-Sc/Cr binary and La-Th-Sc ternary relationships suggest that the Tarfaya basin sediments were deposited in a passive margin setting. The trace <span class="hlt">element</span> ratios of La/Sc, Th/Sc, Cr/Th and Th/Co indicate a felsic source. Moreover, chondrite-normalized REE patterns with light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE) enrichment, a flat heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> (HREE) and negative Eu anomalies can also be attributed to a felsic source for the Tarfaya basin sediments. The Nd isotope model ages (TDM = 2.0-2.2 Ga) of the Early Cretaceous sediments suggest that sediments were derived from the Eburnean terrain (Reguibat Shield). On the other hand, Late Cretaceous to Miocene--Pliocene sediments show younger model ages (TDM = 1.8 Ga, on average) indicating an origin from both the Reguibat Shield and the western Anti-Atlas. In contrast, the southernmost studied Sebkha Aridal section (Oligocene to Miocene-Pliocene) yields older provenance ages (TDM = 2.5-2.6 Ga) indicating that these sediments were dominantly derived from the Archean terrain of the Reguibat Shield.</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 id="translatedtitle">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/2014GeCoA.128...29H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.128...29H"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/10376325','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/10376325"><span id="translatedtitle">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="http://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. PMID:10376325</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JSAES..68..205A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JSAES..68..205A&link_type=ABSTRACT"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2011PhDT.......140S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT.......140S"><span id="translatedtitle">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/2011GeCoA..75.6374F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeCoA..75.6374F"><span id="translatedtitle">Improved provenance tracing of Asian dust sources using rare <span class="hlt">earth</span> <span class="hlt">elements</span> and selected trace <span class="hlt">elements</span> for palaeomonsoon studies on the eastern Tibetan Plateau</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferrat, Marion; Weiss, Dominik J.; Strekopytov, Stanislav; Dong, Shuofei; Chen, Hongyun; Najorka, Jens; Sun, Youbin; Gupta, Sanjeev; Tada, Ryuji; Sinha, Rajiv</p> <p>2011-11-01</p> <p>The Asian Monsoon forms an important part of the <span class="hlt">earth</span>'s climate system, yet our understanding of the past interactions between its different sub-systems, the East Asian and Indian monsoons, and between monsoonal winds and other prevailing wind currents such as the Westerly jet, is limited, particularly in central Asia. This in turn affects our ability to develop climate models capable of accurately predicting future changes in atmospheric circulation patterns and monsoon intensities in Asia. Provenance studies of mineral dust deposited in terrestrial settings such as peat bogs can address this problem directly, by offering the possibility to examine past deposition rates and wind direction, and hence reconstruct past atmospheric circulation patterns. However, such studies are challenged by several issues, most importantly the identification of proxies that unambiguously distinguish between the different potential dust sources and that are independent of particle size. In addition, a single analytical method that is suitable for sample preparation of both dust source (i.e. desert sand, soil) and receptor (i.e. dust archive such as peat or soil profiles) material is desirable in order to minimize error propagation derived from the experimental and analytical work. Here, an improved geochemical framework of provenance tracers to study atmospheric circulation patterns and palaeomonsoon variability in central Asia is provided, by combining for the first time mineralogical as well as major and trace <span class="hlt">elemental</span> (Sc, Y, Th and the rare <span class="hlt">earth</span> <span class="hlt">elements</span>) information on Chinese (central Chinese loess plateau, northern Qaidam basin and Taklamakan, Badain Juran and Tengger deserts), Indian (Thar desert) and Tibetan (eastern Qinghai-Tibetan Plateau) dust sources. Quartz, feldspars and clay minerals are the major constituents of all studied sources, with highly variable calcite contents reflected in the CaO concentrations. Chinese and Tibetan dust sources are enriched in middle</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 id="translatedtitle">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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=geochemistry&id=EJ327326','ERIC'); return false;" href="http://eric.ed.gov/?q=geochemistry&id=EJ327326"><span id="translatedtitle"><span class="hlt">Geochemistry</span> for Chemists.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Hostettler, John D.</p> <p>1985-01-01</p> <p>A <span class="hlt">geochemistry</span> course for chemists is described. Includes: (1) general course information; (2) subject matter covered; and (3) a consideration of the uses of <span class="hlt">geochemistry</span> in a chemistry curriculum, including geochemical "real world" examples, <span class="hlt">geochemistry</span> in general chemistry, and <span class="hlt">geochemistry</span> as an elective. (JN)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JAESc.111..100L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JAESc.111..100L&link_type=ABSTRACT"><span id="translatedtitle">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/2015APS..MAR.H1166T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MAR.H1166T"><span id="translatedtitle">Accurate projected augmented wave (PAW) datasets for rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (RE=La-Lu)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Topsakal, Mehmet; Wentzcovitch, Renata</p> <p>2015-03-01</p> <p>We provide accurate projected augmented wave (PAW) datasets for rare-<span class="hlt">earth</span> (RE) <span class="hlt">elements</span> with some suggested Hubbard U values allowing efficient plane-wave calculations. Solid state tests of generated datasets were performed on rare-<span class="hlt">earth</span> nitrides. Through density of state (DOS) and equation of state (EoS) comparisons, generated datasets were shown to yield excellent results comparable to highly accurate all-electron full-potential linearized augmented plane-wave plus local orbital (FLAPW+LO) calculations. Hubbard U values for trivalent RE ions are determined according to hybrid functional calculations. We believe that these new and open-source PAW datasets will allow further studies on rare-<span class="hlt">earth</span> materials. NSF/EAR 1319361</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27609889','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27609889"><span id="translatedtitle">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="http://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>2016-09-01</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. PMID:27609889</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 id="translatedtitle">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://adsabs.harvard.edu/abs/2012JESS..121.1401H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JESS..121.1401H"><span id="translatedtitle">Metallogenic epoch of the Jiapigou gold belt, Jilin Province, China: Constrains from rare <span class="hlt">earth</span> <span class="hlt">element</span>, fluid inclusion <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>Huang, Zhixin; Yuan, Wanming; Wang, Changming; Liu, Xiangwei; Xu, Xiaotong; Yang, Liya</p> <p>2012-12-01</p> <p>The Jiapigou gold belt is located on the northern margin of the North China Craton, and is one of the most important gold-mining and production regions in the circum-Pacific metallogenic zone. Research has been conducted in this area since the 1960s, however, the timing of the gold mineralisation is still unresolved, and an ideal metallogenic model has not been well established. To address these questions, a systematic geological, geochemical and geochronological investigation was conducted. The study revealed that (i) the gold-bearing quartz veins can be divided into two groups, earlier and later gold-bearing quartz veins according to their occurrence and the geochemical characteristics, (ii) the geochemical characteristics of the ore bodies, while similar to granite, are clearly different from the altered rock, and (iii) the geochemical characteristics of the later gold-bearing quartz veins have more similarity to the altered rock than the earlier gold-bearing quartz veins do. Therefore, we conclude that two independent stages of metallogenesis within the Jiapigou gold deposit area are related to magmatic activity in the Palaeoproterozoic and the Yanshanian stage of the Mesozoic, that the ore-forming fluids are mainly of magmatic origin, and that magma contamination by the altered rock was stronger in the Mesozoic. Zircon LA-ICP-MS U-Pb data show that the age of the Palaeoproterozoic granite is ~2426.0 Ma and that of the Mesozoic granite is ~166.2 Ma; these ages can be interpreted as the maximum ages of the two periods of gold mineralisation. In addition to investigating the geotectonic and regional structure of the Jiapigou gold belt, this study also proposes that the WNW-trending zone of gold mineralisation is a result of a magmatic event within the basement in the early Palaeoproterozoic, and that large-scale sinistral strike-slip displacements of the Huifahe and Liangjiang Faults in the late Middle Triassic (Yanshanian epoch) controlled the later tectono-magmatic event and the NNE-ENE-trending zone of gold mineralisation.</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 id="translatedtitle">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/2014AGUFMEP12B..07E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP12B..07E"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2012AGUFM.V11A2743K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V11A2743K"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of zircons from mineralizing and non-mineralizing igneous rocks related to gold ores at Yanacocha, Peru</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koleszar, A. M.; Dilles, J. H.; Kent, A. J.; Wooden, J. L.</p> <p>2012-12-01</p> <p>Zircons record important details about the evolution of magmatic systems, are relatively insensitive to alteration, and have been used to investigate the <span class="hlt">geochemistry</span>, temperature, and oxidation state of volcanic and plutonic system. We examine zircons that span 6-7 m.y. of calc-alkaline volcanic activity in the Yanacocha district of northern Peru, where dacitic intrusions are associated with high-sulfidation gold deposits. The 14.5-8.4 Ma Yanacocha Volcanics include cogenetic lavas and pyroclastic rocks and are underlain by the andesites and dacites of the Calipuy Group, the oldest Cenozoic rocks in the region. We present data for magmatic zircons from the Cerro Fraile dacitic pyroclastics (15.5-15.1 Ma) of the Calipuy Group, and multiple eruptive units within the younger Yanacocha Volcanics: the Atazaico Andesite (14.5-13.3 Ma), the Quilish Dacite (~14-12 Ma), the Azufre Andesite (12.1-11.6 Ma), the San Jose Ignimbrite (11.5-11.2 Ma), and the Coriwachay Dacite (11.1-8.4 Ma). Epithermal high sulfidation (alunite-bearing) gold deposits are associated with the dacite intrusions of the Coriwachay and Quilish Dacites. Zircons from the non-mineralizing rocks typically have lower Hf concentrations and record Ti-in-zircon temperatures that are ~100°C hotter than zircons from the mineralizing intrusions. Temperatures recorded by zircons from the mineralizing intrusions are remarkably similar to those of the underlying Cerro Fraile dacite pyroclastics, but the zircons discussed here generally record SHRIMP-RG 206Pb/238U ages within error of previously published Ar-Ar eruption ages (eliminating antecrystic or xenocrystic origins). These observations suggest that zircons in the mineralizing intrusions form after greater extents of crystallization (and thus record elevated Hf concentrations and lower temperatures) than do zircons in the non-mineralized deposits. Unlike zircons from mineralized units associated with the porphyry Cu(Mo) deposits in Yerington, Nevada, which</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 id="translatedtitle">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://www.osti.gov/scitech/biblio/20019001','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20019001"><span id="translatedtitle">Extraction of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> from nitric solutions by phosphoryl-containing podands</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Turanov, A.N.; Karandashev, V.K.; Baulin, V.E.</p> <p>1999-11-01</p> <p>The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO{sub 3} solutions by phosphoryl-containing podands of various structures has been studied.. It has been found that the maximum extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> is exhibited by reagents containing one ether oxygen atom in the molecule, bound to diphenylphosphoryl or ditolylphosphoryl groups by methylene and o-phenylene fragments. The structure of these reagents is best suited for the polydentate coordination of the ligand and the conditions of a chelate complex formation. The effect of HNO{sub 3} concentration in the aqueous phase and that of the nature of an organic diluent on the extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and Y are considered. Stoichiometric of the extracted complexes has been determined and the extraction constants calculated.</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://www.osti.gov/scitech/biblio/21541284','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21541284"><span id="translatedtitle">Symmetric charge-transfer cross sections of IIIa rare-<span class="hlt">earth</span>-metal <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hashida, Masaki; Sakabe, Shuji; Izawa, Yasukazu</p> <p>2011-03-15</p> <p>Symmetric charge-transfer cross sections of IIIa rare-<span class="hlt">earth</span>-metal <span class="hlt">elements</span> (Sc, Y, and Gd) in the impact energy range of 30 to 1000 eV were measured for the first time. The experiments were performed with a crossed-beam apparatus that featured primary ion production by photoionization with a tunable dye laser. Comparing the cross sections of IIIa rare-<span class="hlt">earth</span>-metal <span class="hlt">elements</span> ({sigma}{sub Sc}, {sigma}{sub Y}, and {sigma}{sub Gd}) with those of alkali metals or helium {sigma}{sub 0}, we found that {sigma}{sub 0{approx_equal}{sigma}Sc}<{sigma}{sub Y}<{sigma}{sub Gd{approx_equal}}2{sigma}{sub 0}at an impact energy of 1000 eV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17837193','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17837193"><span id="translatedtitle">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="http://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. PMID:17837193</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25164252','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25164252"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Chuncai; Liu, Guijian; Cheng, Siwei; Fang, Ting; Lam, Paul K S</p> <p>2014-01-01</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. PMID:25164252</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 id="translatedtitle">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('http://www.ncbi.nlm.nih.gov/pubmed/11529577','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11529577"><span id="translatedtitle">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="http://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. PMID:11529577</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22304002','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22304002"><span id="translatedtitle">Evaluating rare <span class="hlt">earth</span> <span class="hlt">element</span> availability: a case with revolutionary demand from clean technologies.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alonso, Elisa; Sherman, Andrew M; Wallington, Timothy J; Everson, Mark P; Field, Frank R; Roth, Richard; Kirchain, Randolph E</p> <p>2012-03-20</p> <p>The future availability of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) is of concern due to monopolistic supply conditions, environmentally unsustainable mining practices, and rapid demand growth. We present an evaluation of potential future demand scenarios for REEs with a focus on the issue of comining. Many assumptions were made to simplify the analysis, but the scenarios identify some key variables that could affect future rare <span class="hlt">earth</span> markets and market behavior. Increased use of wind energy and electric vehicles are key <span class="hlt">elements</span> of a more sustainable future. However, since present technologies for electric vehicles and wind turbines rely heavily on dysprosium (Dy) and neodymium (Nd), in rare-<span class="hlt">earth</span> magnets, future adoption of these technologies may result in large and disproportionate increases in the demand for these two <span class="hlt">elements</span>. For this study, upper and lower bound usage projections for REE in these applications were developed to evaluate the state of future REE supply availability. In the absence of efficient reuse and recycling or the development of technologies which use lower amounts of Dy and Nd, following a path consistent with stabilization of atmospheric CO(2) at 450 ppm may lead to an increase of more than 700% and 2600% for Nd and Dy, respectively, over the next 25 years if the present REE needs in automotive and wind applications are representative of future needs. PMID:22304002</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JPS...195.3735R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JPS...195.3735R"><span id="translatedtitle">Hydrometallurgical separation of rare <span class="hlt">earth</span> <span class="hlt">elements</span>, cobalt and nickel from spent nickel-metal-hydride batteries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodrigues, Luiz Eduardo Oliveira Carmo; Mansur, Marcelo Borges</p> <p></p> <p>The separation of rare <span class="hlt">earth</span> <span class="hlt">elements</span>, cobalt and nickel from NiMH battery residues is evaluated in this paper. Analysis of the internal content of the NiMH batteries shows that nickel is the main metal present in the residue (around 50% in weight), as well as potassium (2.2-10.9%), cobalt (5.1-5.5%), rare <span class="hlt">earth</span> <span class="hlt">elements</span> (15.3-29.0%) and cadmium (2.8%). The presence of cadmium reveals that some Ni-Cd batteries are possibly labeled as NiMH ones. The leaching of nickel and cobalt from the NiMH battery powder with sulfuric acid is efficient; operating variables temperature and concentration of H 2O 2 has no significant effect for the conditions studied. A mixture of rare <span class="hlt">earth</span> <span class="hlt">elements</span> is separated by precipitation with NaOH. Finally, solvent extraction with D2EHPA (di-2-ethylhexyl phosphoric acid) followed by Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) can separate cadmium, cobalt and nickel from the leach liquor. The effect of the main operating variables of both leaching and solvent extraction steps are discussed aiming to maximize metal separation for recycling purposes.</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 id="translatedtitle">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> <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 id="translatedtitle">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://adsabs.harvard.edu/abs/2002AGUFM.V22B1236A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.V22B1236A"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of Fresh Submarine HSDP-2 Glasses from Mauna Kea Volcano: Unexpected Mobility of 'Immobile' Trace <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>Amini, M. A.; Jochum, K. P.; Stoll, B.; Willbold, M.; Sobolev, A. V.; Hofmann, A. W.</p> <p>2002-12-01</p> <p>The Hawaii Scientific Drilling Project-2 provides the opportunity to investigate the geochemical evolution of the submarine section of Mauna Kea. Our previous analyses of bulk-rock trace <span class="hlt">element</span> concentrations had revealed relatively high degrees of scatter of trace <span class="hlt">element</span> ratios such as Th/U, Ta/U and even Nb/Ta, and we suspected that many of the samples had been affected by seawater alteration. Fortunately, fresh glasses are found throughout the drill core in many glass-rich hyaloclastic and pillow basalts with glass proportions up to 10%. We therefore determined incompatible trace <span class="hlt">elements</span> such as Th, U, Nb, Ta, Zr, Ba, Pb, Rb in carefully handpicked, fresh glasses in 16 samples derived from depths between 1310 m and 3050 m. The samples were crushed to less than 0.425 mm grain size in order to obtain very fresh glass fragments free of contamination by alteration products, olivines or other minerals. The glass fractions and their corresponding bulk samples were analyzed for major and trace <span class="hlt">elements</span> by EMP, MIC-SSMS and HR-ICPMS. The differences between glass and bulk are particularly obvious in Pb, Rb, Cs and U. As expected, Pb, Rb and Cs were found to be mobile, with concentrations in the bulk samples varying by up to a factor of 5 relative to the glass samples. Similarly, U concentrations in glass are up to a factor of 2 higher than in bulk samples. More surprising is the observation that Th and Ta are quite probably mobile, because these <span class="hlt">elements</span> are normally believed to be immobile. However, these results are consistent with those of Bienvenue et al. (1990), who found that Th appears to be sensitive to seawater alteration. Our glass data indicate that Ta/U (3.7+/-0.2) is uniform along the sequence, in contrast to the bulk data which show a large scatter (3.7-6.5). Th/U ratios in the glasses show a maximum (~3.5) at a depth of ~2100 m, whereas low ratios of about 3 were found in depths of 1300-1400 m and 2800-3000 m. The high Th/U ratios in the 2100 m region</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 id="translatedtitle">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://www.osti.gov/scitech/biblio/273576','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/273576"><span id="translatedtitle">Determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in environmental materials by inductively coupled plasma mass spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Panday, V.K.; Hoppstock, K.; Becker, J.S.; Dietze, H.J.</p> <p>1996-09-01</p> <p>Despite the fact that rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) have found increasing use in modern technology only few data are available on their concentrations in biological and environmental samples. Inductively coupled plasma mass spectrometry (ICP-MS) has been employed to study the concentration of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in various environmental materials (e.g., pine needles, mussel tissue, apple leaves) available from National Institute of Standards and Technology (NIST), the Bureau of European Communities (BCR), and the German Environmental Specimens Bank. After the decomposition of the environmental samples with HNO{sub 3}, the REE (present mostly in the ng/g-range) were separated from the matrix and simultaneously preconcentrated using liquid-liquid extraction with bis(2-ethyl hexyl)-ortho-phosphoric acid (HDEHP) in toluene as a selective reagent at pH = 2 and subsequent back extraction of the <span class="hlt">elements</span> into the aqueous by 6M HNO{sub 3}. Recoveries of better 90% were obtained for almost all REE. A Perkin Elmer/Sciex ELAN 5000 ICP-MS and HR-ICP-MS <span class="hlt">ELEMENT</span> from Finnigan MAT were used for quantitative analysis (by external calibration and ID-ICP-MS) of REE. The results of determination of REE concentrations agree well with the data available on some of these materials. Further supplement information on the contents of various REE in these materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GeCoA..66.3417J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GeCoA..66.3417J"><span id="translatedtitle">Reconciling the <span class="hlt">elemental</span> and Sr isotope composition of Himalayan weathering fluxes: insights from the carbonate <span class="hlt">geochemistry</span> of stream waters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jacobson, Andrew D.; Blum, Joel D.; Walter, Lynn M.</p> <p>2002-10-01</p> <p>Determining the relative proportions of silicate vs. carbonate weathering in the Himalaya is important for understanding atmospheric CO 2 consumption rates and the temporal evolution of seawater Sr. However, recent studies have shown that major <span class="hlt">element</span> mass-balance equations attribute less CO 2 consumption to silicate weathering than methods utilizing Ca/Sr and 87Sr/ 86Sr mixing equations. To investigate this problem, we compiled literature data providing <span class="hlt">elemental</span> and 87Sr/ 86Sr analyses for stream waters and bedrock from tributary watersheds throughout the Himalaya Mountains. In addition, carbonate system parameters (P CO 2, mineral saturation states) were evaluated for a selected suite of stream waters. The apparent discrepancy between the dominant weathering source of dissolved major <span class="hlt">elements</span> vs. Sr can be reconciled in terms of carbonate mineral equilibria. Himalayan streams are predominantly Ca 2+-Mg 2+-HCO 3- waters derived from calcite and dolomite dissolution, and mass-balance calculations demonstrate that carbonate weathering contributes ˜87% and ˜76% of the dissolved Ca 2+ and Sr 2+, respectively. However, calculated Ca/Sr ratios for the carbonate weathering flux are much lower than values observed in carbonate bedrock, suggesting that these divalent cations do not behave conservatively during stream mixing over large temperature and P CO 2 gradients in the Himalaya. The state of calcite and dolomite saturation was evaluated across these gradients, and the data show that upon descending through the Himalaya, ˜50% of the streams evaluated become highly supersaturated with respect to calcite as waters warm and degas CO 2. Stream water Ca/Mg and Ca/Sr ratios decrease as the degree of supersaturation with respect to calcite increases, and Mg 2+, Ca 2+, and HCO 3- mass balances support interpretations of preferential Ca 2+ removal by calcite precipitation. On the basis of patterns of saturation state and P CO 2 changes, calcite precipitation was estimated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JVGR...80...85B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JVGR...80...85B"><span id="translatedtitle">Isotope (Sr, Nd, Pb, O) and trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of volcanics from the Erta'Ale range (Ethiopia)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barrat, J. A.; Fourcade, S.; Jahn, B. M.; Cheminée, J. L.; Capdevila, R.</p> <p>1998-01-01</p> <p>The Erta'Ale range is the most important axial volcanic chain of the Afar region. The petrographic diversity of lavas erupted in this area is very important, ranging from magnesian transitional basalts to rhyolites. The variation in isotopic compositions and incompatible <span class="hlt">element</span> ratios in the basalts (e.g., ɛNd = +4.5 to +7.5, ( {La}/{Yb}) n = 2.5 to 11) demonstrates the heterogeneous character for their mantle sources. Such heterogeneity can be interpreted by the participation of two mantle reservoirs: a depleted MORB and a HIMU OIB-type sources. These reservoirs are indistinguishable from those recently identified in the southern part of the Red Sea region. The isotopic data indicate that the contribution of continental sialic components is not significant in the petrogenesis of the volcanic rocks. Our data further suggest that the crust beneath the Erta'Ale volcanic range is not a thinned (Pan-african?) sialic crust, but could be gabbroic in nature. The acid volcanics have originated mostly through fractional crystallisation of basaltic magmas as revealed from major- and trace-<span class="hlt">element</span> data and from the relatively homogeneous Sr and Nd isotopic ratios. However, the δ18O variation in the acid lavas suggests an important contribution from a low δ18O component in the petrogenesis of some low δ 18O acid lavas.</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 id="translatedtitle">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 id="translatedtitle">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/2014JAESc..95..228C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAESc..95..228C"><span id="translatedtitle">Petrogenesis of Late Permian sodic metagranitoids in southeastern Korea: SHRIMP zircon geochronology and <span class="hlt">elemental</span> and Nd-Hf isotope <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>Cheong, Chang-sik; Kim, Namhoon; Kim, Jeongmin; Yi, Keewook; Jeong, Youn-Joong; Park, Chan-Soo; Li, Huai-kun; Cho, Moonsup</p> <p>2014-12-01</p> <p>One of the striking tectonomagmatic features recently found in southeastern Korea is the occurrence of ca. 250 Ma high-silica adakite. Sodic metagranitoids mainly consisting of tonalitic-trondhjemitic-granodioritic gneisses occur in the Andong-Cheongsong area adjacent to the Yeongdeok adakite site. To investigate temporal and petrogenetic relationships of these orthogneisses with the adakite, we conducted SHRIMP zircon U-Pb dating as well as <span class="hlt">elemental</span> and Nd-Hf isotopic analyses. Zircon core ages of the orthogneisses (ca. 262-251 Ma) confirm the widespread occurrence of arc-related Late Permian magmatism in southeastern Korea. The Late Triassic (ca. 230 Ma) zircon overgrowths reflect a thermal overprint probably related to the initiation of another subduction system. The analyzed orthogneisses have major <span class="hlt">element</span> compositions comparable to the Phanerozoic adakites and Archean TTG suite, such as high SiO2 (58.7-65.5 wt.%) and Al2O3 (17.1-19.1 wt.%) contents and Na2O/K2O ratios (1.83-4.95). However, their moderate Sr/Y (35-43) and La/Yb (14-53) ratios and negative Eu anomalies (Eu/Eu* = 0.75-0.95) are incompatible with the key features reported from the Yeongdeok adakite. Moreover, initial whole-rock εNd (-7.9 to -3.3) and zircon εHf (-0.3 ± 2.4) values of the orthogneisses negate a direct derivation from the subducted slab. Our <span class="hlt">elemental</span> and Nd-Hf isotopic data collectively suggest that the protoliths of the tonalitic-trondhjemitic-granodioritic gneisses were generated by partial melting of mafic lower crust at depths shallower than the garnet stability field. Our Nd and Hf model ages of the gneisses, together with those previously reported from the Mesozoic granitoids indicate a selective involvement of young source materials along the margin of the Yeongnam massif. The Hf isotopic compositions of zircons from a trondhjemitic gneiss attest to the involvement of primitive melts during their crystallization. The ridge subduction and consequent development of a slab</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 id="translatedtitle">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://www.osti.gov/scitech/biblio/1261279','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1261279"><span id="translatedtitle">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://www.osti.gov/pages/biblio/1261279-quantification-rare-earth-elements-using-laser-induced-breakdown-spectroscopy','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1261279-quantification-rare-earth-elements-using-laser-induced-breakdown-spectroscopy"><span id="translatedtitle">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 PAGESBeta</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 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> </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('http://www.ncbi.nlm.nih.gov/pubmed/17208446','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17208446"><span id="translatedtitle">Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in Egyptian granite by instrumental neutron activation analysis.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>El-Taher, A</p> <p>2007-04-01</p> <p>The mobilization of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in the environment requires monitoring of these <span class="hlt">elements</span> in environmental matrices, in which they are mainly present at trace levels. The similarity in REEs chemical behavior makes the separate determination of each <span class="hlt">element</span> by chemical methods difficult; instrumental neutron activation analysis (INAA), based on nuclear properties of the <span class="hlt">elements</span> to be determined, is a method of choice in trace analysis of REEs and related <span class="hlt">elements</span>. Therefore, INAA was applied as a sensitive nondestructive analytical tool for the determination of REEs to find out what information could be obtained about the REEs of some Egyptian granite collected from four locations in Aswan area in south Egypt as follows wadi El-Allaqi, El-Shelal, Gabel Ibrahim Pasha and from Sehyel Island and to estimate the accuracy, reproducibility and detection limit of NAA method in case of the given samples. The samples were properly prepared together with standards and simultaneously irradiated in a neutron flux of 7 x 10(11)n/cm(2)s in the TRIGA Mainz research reactor facilities. The following <span class="hlt">elements</span> have been determined: La, Ce, Nd, Sm, Eu, Yb and Lu. The gamma spectra was collected by HPGe detector and the analysis was done by means of computerized multichannel analyzer. The X-ray fluorescence (XRF) was also used. PMID:17208446</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 id="translatedtitle">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://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.3552S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.3552S&link_type=ABSTRACT"><span id="translatedtitle">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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015SPIE.9482E..0GM&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015SPIE.9482E..0GM&link_type=ABSTRACT"><span id="translatedtitle">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 id="translatedtitle">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> <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 id="translatedtitle">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('http://www.osti.gov/scitech/servlets/purl/1265838','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1265838"><span id="translatedtitle">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://adsabs.harvard.edu/abs/2015NatSR...512483W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...512483W"><span id="translatedtitle">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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Lingqing; Liang, Tao</p> <p>2015-07-01</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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510494','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510494"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/26198417','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26198417"><span id="translatedtitle">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=pubmed">PubMed</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 × 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. PMID:26198417</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24681591','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24681591"><span id="translatedtitle">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="http://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. PMID:24681591</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23896401','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23896401"><span id="translatedtitle">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="http://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%). PMID:23896401</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Litho.152...56M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Litho.152...56M"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of nyerereite and gregoryite phenocrysts from natrocarbonatite lava, Oldoinyo Lengai, Tanzania: Implications for magma mixing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitchell, Roger H.; Kamenetsky, Vadim S.</p> <p>2012-11-01</p> <p>The abundances of Li, P, Cl, V, Mn, Rb, Sr, Y, Cs, Ba, Pb, Th, U and REE, within and between, phenocrysts of nyerereite and gregoryite occurring in natrocarbonatite lavas erupted from the active volcano Oldoinyo Lengai (Tanzania) have been determined by electron microprobe, LA-ICP-MS and SIMS. These data show that, in general, nyerereite is enriched in Rb (71-137 ppm), Sr (14,485-23,240 ppm), Y (2.0-8.9 ppm), Cs (1.6-5.3 ppm), Ba (4000-11,510 ppm), but poorer in Li (21-91 ppm), P (820-1900 ppm) and V (5.1-47 ppm) relative to gregoryite (Rb = 43-106; Sr = 4255-7275; Y = 0.3-4.0; Cs = 0.6-5.1; Ba = 1125-7052; Li 84-489; P = 6790-15,860; V = 33-155 ppm). Nyerereite is highly enriched in REE (La = 236-973; Ce = 395-1044 ppm) relative to gregoryite (La = 59-309; Ce = 59-301 ppm). Chondrite normalized REE distribution patterns for nyerereite and gregoryite are parallel and linear with no Eu anomalies. They show extreme enrichment in light REE and depletion in heavy REE (nyerereite La/YbCN = 1759-7079; gregoryite La/YbCN = 1051-10,247). Significant differences exist in the abundances of trace <span class="hlt">elements</span> within and between coexisting crystals occurring in diverse natrocarbonatite flows, although there do not appear to be any significant secular variations in phenocryst compositions in lavas erupted from a given vent. It is concluded that both major, minor and trace <span class="hlt">element</span> compositional data for nyerereite and gregoryite phenocrysts occurring in natrocarbonatite lavas are derived by the crystallization of several different batches of magma in a continuously replenished fractionating magma chamber. Natrocarbonatite lavas are considered to be hybrids formed by the mixing of both crystals and melts formed from several batches of natrocarbonatite magma; thus bulk rock compositions cannot represent the compositions of the primary magma composition before the onset of fractionation. Differentiation of natrocarbonatite melts leads to enrichment of residua in Ba and Mg.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V23B3129B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V23B3129B&link_type=ABSTRACT"><span id="translatedtitle">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/2006AGUFM.V31A0563M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V31A0563M"><span id="translatedtitle">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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..18.9828W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..18.9828W&link_type=ABSTRACT"><span id="translatedtitle">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/1990E%26PSL.101..233B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990E%26PSL.101..233B"><span id="translatedtitle">Mantle heterogeneity in northeastern Africa: evidence from Nd isotopic compositions and hygromagmaphile <span class="hlt">element</span> <span class="hlt">geochemistry</span> of basaltic rocks from the Gulf of Tadjoura and southern Red Sea regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barrat, J.-A.; Jahn, B. M.; Joron, J.-L.; Auvray, B.; Hamdi, H.</p> <p>1990-12-01</p> <p>Basaltic rocks from the Gulf of Tadjoura and southern Red Sea regions have been analysed for their Nd isotopic compositions and major and trace <span class="hlt">element</span> concentrations. The wide variation in isotopic and geochemical compositions of the basaltic rocks is best explained by the mixing phenomenon involving a variety of mantle source components. To test the mixing hypothesis, a combined use of Nd isotopes and hygromagmaphile <span class="hlt">elemental</span> ratios is proven very powerful. Three reservoirs have been identified as minimum components in their petrogenesis: (1) DMM (depleted MORB mantle), a mantle source depleted in light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE), which is the principal component of the N-MORB type basalts of this region; (2) REC (Ramad enriched component), equivalent to the hot-spot type of source detected in the south of Red Sea; (3) TEC (Tadjoura enriched component), a rather unique component located in the region of Tadjoura Gulf; it is characterised by a relative depletion in Rb, K, Th and U in a primitive mantle- or chondrite-normalised incompatible <span class="hlt">element</span> pattern; this component could have been produced by mantle metasomatism of an originally depleted mantle. Mixing in various proportions of the above components is considered to be the principal mechanism for the formation of basalts with such diverse isotopic and trace <span class="hlt">element</span> compositions.</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 id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/26782327','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26782327"><span id="translatedtitle"><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="http://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. PMID:26782327</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 id="translatedtitle">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> </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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhDT.........1E&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhDT.........1E&link_type=ABSTRACT"><span id="translatedtitle">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/2060/20100025482','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100025482"><span id="translatedtitle">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('http://hdl.handle.net/2060/20150002835','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002835"><span id="translatedtitle">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://www.osti.gov/scitech/biblio/21269172','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21269172"><span id="translatedtitle">NEW RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENT</span> ABUNDANCE DISTRIBUTIONS FOR THE SUN AND FIVE r-PROCESS-RICH VERY METAL-POOR STARS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sneden, Christopher; Lawler, James E.; Den Hartog, Elizabeth A.; Cowan, John J.; Ivans, Inese I. E-mail: jelawler@wisc.edu E-mail: cowan@nhn.ou.edu</p> <p>2009-05-15</p> <p>We have derived new abundances of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five <span class="hlt">elements</span> are in good agreement with meteoritic abundances. For the low-metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other <span class="hlt">elements</span> in individual stars, to produce internally consistent Ba, rare <span class="hlt">earth</span>, and Hf (56 {<=} Z {<=} 72) <span class="hlt">element</span> distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeCoA..70.3702B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeCoA..70.3702B"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the 1991 Mt. Pinatubo silicic melts, Philippines: Implications for ore-forming potential of adakitic magmatism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Borisova, Anastassia Yu.; Pichavant, Michel; Polvé, Mireille; Wiedenbeck, Michael; Freydier, Remi; Candaudap, Frédéric</p> <p>2006-07-01</p> <p>The dacite pumice erupted from Mt. Pinatubo on June 15, 1991 (whole-rock, rhyolitic groundmass glasses and homogenized melt inclusions) has been analyzed using inductively coupled plasma-mass spectrometry (ICP-MS), nanosecond and femtosecond laser ablation ICP-MS and secondary ion mass spectrometry (SIMS) to evaluate its ore-forming potential. Data suggest that adakite magmas are metal-rich and concentrate ore metals during magmatic differentiation. Sulfides segregate in limited amounts under the hydrous, oxidizing conditions typical of adakitic magmas resulting in incompatible behavior for Au (6-22 ppb), Cu (26-77 ppm), and Pb, Mo, As, and Sb in melts of dacitic to rhyolitic compositions. Metal transfer from this adakite magma to the coexisting aqueous phase was favored by the peraluminous composition of the rhyolitic melt and high aqueous chloride concentrations. Mass balance calculations suggest that the pre-eruptive aqueous phase could have extracted a minimum of 100 t Au and 5 × 10 5 t Cu from the Mt. Pinatubo magma. Our data suggest that intrusives having adakitic signatures are genetically associated with Au-Cu and Cu-Mo mineralization, auriferous porphyry copper deposits, and epithermal gold veins. High H 2O, Cl, Sr/Y, Pb/Ce, Mo/Ce, As/Ce and Sb/Ce in Mt. Pinatubo melts reflect the contribution of deep fluids derived from subducted sediments and altered MORBs in the dacite genesis. The slab-derived fluids carrying mobile <span class="hlt">elements</span> are likely responsible for the enrichment of adakite magmas in gold, associated metals and H 2O, and may explain the exceptional ore-forming potential of adakite magmatism.</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 id="translatedtitle">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://adsabs.harvard.edu/abs/2015SPIE.9673E..06W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9673E..06W"><span id="translatedtitle">Study on the activated laser welding of ferritic stainless steel with rare <span class="hlt">earth</span> <span class="hlt">elements</span> yttrium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Yonghui; Hu, Shengsun; Shen, Junqi</p> <p>2015-10-01</p> <p>The ferritic stainless steel SUS430 was used in this work. Based on a multi-component activating flux, composed of 50% ZrO2, 12.09 % CaCO3, 10.43 % CaO, and 27.49 % MgO, a series of modified activating fluxes with 0.5%, 1%, 2%, 5%, 10%, 15%, and 20% of rare <span class="hlt">earth</span> (RE) <span class="hlt">element</span> yttrium (Y) respectively were produced, and their effects on the weld penetration (WP) and corrosion resistant (CR) property were studied. Results showed that RE <span class="hlt">element</span> Y hardly had any effects on increasing the WP. In the FeCl3 spot corrosion experiment, the corrosion rates of almost all the samples cut from welded joints turned out to be greater than the parent metal (23.51 g/m2 h). However, there was an exception that the corrosion rate of the sample with 5% Y was only 21.96 g/m2 h, which was even better than parent metal. The further Energy Dispersive Spectrometer (EDS) test showed the existence of <span class="hlt">elements</span> Zr, Ca, O, and Y in the molten slag near the weld seam while none of them were found in the weld metal, indicating the direct transition of <span class="hlt">element</span> from activating fluxes to the welding seam did not exist. It was known that certain composition of activating fluxes effectively restrain the loss of Cr <span class="hlt">element</span> in the process of laser welding, and as a result, the CR of welded joints was improved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850010583&hterms=Earth+plate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DEarth%2Bplate','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850010583&hterms=Earth+plate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DEarth%2Bplate"><span id="translatedtitle"><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>Carr, M. H.</p> <p>1984-01-01</p> <p>The following aspects of the planet <span class="hlt">Earth</span> are discussed: plate tectonics, the interior of the planet, the formation of the <span class="hlt">Earth</span>, and the evolution of the atmosphere and hydrosphere. The <span class="hlt">Earth</span>'s crust, mantle, and core are examined along with the bulk composition of the planet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH51D1921Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH51D1921Q"><span id="translatedtitle">Equivalent Body Force Finite <span class="hlt">Elements</span> Method and 3-D <span class="hlt">Earth</span> Model Applied In 2004 Sumatra Earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qu, W.; Cheng, H.; Shi, Y.</p> <p>2015-12-01</p> <p>The 26 December 2004 Sumatra-Andaman earthquake with moment magnitude (Mw) of 9.1 to 9.3 is the first great earthquake recorded by digital broadband, high-dynamic-range seismometers and global positioning system (GPS) equipment, which recorded many high-quality geophysical data sets. The spherical curvature is not negligible in far field especially for large event and the real <span class="hlt">Earth</span> is laterally inhomogeneity and the analytical results still are difficult to explain the geodetic measurements. We use equivalent body force finite <span class="hlt">elements</span> method Zhang et al. (2015) and mesh the whole <span class="hlt">earth</span>, to compute global co-seismic displacements using four fault slip models of the 2004 Sumatra earthquake provided by different authors. Comparisons of calculated co-seismic displacements and GPS show that the confidences are well in near field for four models, and the confidences are according to different models. In the whole four models, the Chlieh model (Chlieh et al., 2007) is the best as this slip model not only accord well with near field data but also far field data. And then we use the best slip model, Chlieh model to explore influence of three dimensional lateral <span class="hlt">earth</span> structure on both layered spherically symmetric (PREM) and real 3-D heterogeneous <span class="hlt">earth</span> model (Crust 1.0 model and GyPSuM). Results show that the effects of 3-D heterogeneous <span class="hlt">earth</span> model are not negligible and decrease concomitantly with increasing distance from the epicenter. The relative effects of 3-D crust model are 23% and 40% for horizontal and vertical displacements, respectively. The effects of the 3-D mantle model are much smaller than that of 3-D crust model but with wider impacting area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27154643','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27154643"><span id="translatedtitle">Application of solid phase extraction procedures for rare <span class="hlt">earth</span> <span class="hlt">elements</span> determination in environmental samples.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pyrzynska, Krystyna; Kubiak, Anna; Wysocka, Irena</p> <p>2016-07-01</p> <p>Determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in environmental samples requires often pre-concentration and separation step due to a low metal content and high concentration of the interfering matrix components. A solid phase extraction technique with different kind of solid sorbents offers a high enrichment factor, rapid phase separation and the possibility of its combination with various detection techniques used either in on-line or off-line mode. The recent developments in this area published over the last five years are presented and discussed in this paper. PMID:27154643</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..112a2001A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..112a2001A"><span id="translatedtitle">Extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> from hydrate-phosphate precipitates of apatite processing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andropov, M. O.; Anufrieva, A. V.; Buynovskiy, A. S.; Makaseev, Y. N.; Mazov, I. N.; Nefedov, R. A.; Sachkov, V. I.; Stepanova, O. B.; Valkov, AV</p> <p>2016-01-01</p> <p>The features of extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) were considered from hydrate-phosphate precipitates of REE of apatite processing by nitric acid technology. The preliminary purification of nitrate solution of REE from impurities of titanium, aluminum, iron, uranium and thorium was suggested to obtain stable solutions not forming precipitates. Washing the extract was recommended with the evaporated reextract that allows to obtain directly on the cascade of REE extraction the concentrated solutions suitable for the separation into groups by the extraction method. Technical decisions were suggested for the separation of REE in groups without the use of salting-out agent.</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 id="translatedtitle">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/2015CryRp..60..921M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CryRp..60..921M"><span id="translatedtitle">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/2011AGUFM.T51J..06S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.T51J..06S"><span id="translatedtitle">Thickening and propagation of the Pamir plateau: insights from monazite and titanite geochronology and trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span>, eastern Tajikistan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stearns, M. A.; Hacker, B. R.; Kylander-Clark, A. R.; Ratschbacher, L.; Seward, G.</p> <p>2011-12-01</p> <p>The Pamir plateau contains extensive exposures of mid-lower crust, depths not widely exposed in the Tibetan plateau. Determining the spatial and temporal patterns of crustal thickening of the Pamir plateau is critical for understanding how orogenic plateaux are constructed and propagate. The Pamir dome cores consist of upper-amphibolite facies para- and orthogneisses and schists, with the characteristic peak mineral assemblage of kyanite + biotite + garnet ± muscovite in pelites. Thermobarometry indicates peak metamorphism at 600-750°C and 6-10 kbar, representing exhumation depths of 20-35 km (McGraw et al., in review). U-Th-Pb ages of monazite and titanite from the Pamir domes were determined to investigate the timing of thickening and cooling of the mid to lower crust. The closure temperatures of monazite (≥700 °C) and titanite (~650-700 °C) make them especially useful geochronometers for dating high-grade metamorphism. Additionally, maps of yttrium (Y) in monazite and garnet and Zr-in-titanite thermometry allow more robust interpretations of isotopic age information. Ages were obtained using laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) following the acquisition of backscattered electron and x-ray <span class="hlt">element</span> maps to characterize grain zoning and guide LA-ICP-MS spot placement. The monazites in the rock matrix and as garnet inclusions are chiefly Cenozoic and range from 30 to 18 Ma. They record crystallization during prograde and peak metamorphism, based on textures and compositions. The dated titanites are exclusively polycrystalline aggregates recrystallized during metamorphism. They range from 40 to 10 Ma and define two populations of ~40-32 Ma and ~19-10 Ma. The older titanite ages are restricted to the central Pamir where metamorphic temperatures were <650°C, and the youngest ages come from the southern Pamir, where metamorphic temperatures were above titanite closure to Pb. The oldest ages are therefore</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/2003/0477/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/2003/0477/"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/26674238','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26674238"><span id="translatedtitle">An EDTA-β-cyclodextrin material for the adsorption of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and its application in preconcentration of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in seawater.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Feiping; Repo, Eveliina; Meng, Yong; Wang, Xueting; Yin, Dulin; Sillanpää, Mika</p> <p>2016-03-01</p> <p>The separation and recovery of Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) from diluted aqueous streams has attracted great attention in recent years because of ever-increasing REEs demand. In this study, a green synthesized EDTA-cross-linked β-cyclodextrin (EDTA-β-CD) biopolymer was prepared and employed in adsorption of aqueous REEs, such as La(III), Ce(III), and Eu(III). EDTA acts not only as cross-linker but also as coordination site for binding of REEs. The adsorption properties for the adsorption of REEs by varying experimental conditions were carried out by batch tests. The kinetics results revealed that the surface chemical sorption and the external film diffusion were the rate-determining steps of the adsorption process. The obtained maximum adsorption capacities of EDTA-β-CD were 0.343, 0.353, and 0.365mmolg(-1) for La(III), Ce(III) and Eu(III), respectively. Importantly, the isotherms fitted better to Langmuir than Freundlich and Sips models, suggesting a homogenous adsorption surface for REEs on the adsorbent. Moreover, the multi-component adsorption, which was modeled by extended Sips isotherms, revealed adsorbent's selectivity to Eu(III). More significantly, the successful recoveries of the studied ions from tap water and seawater samples makes EDTA-β-CD a promising sorbent for the preconcentration of REEs from diluted aqueous streams. PMID:26674238</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.411..142E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.411..142E"><span id="translatedtitle">Partitioning of light lithophile <span class="hlt">elements</span> during basalt eruptions on <span class="hlt">Earth</span> and application to Martian shergottites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Edmonds, Marie</p> <p>2015-02-01</p> <p>An enigmatic record of light lithophile <span class="hlt">element</span> (LLE) zoning in pyroxenes in basaltic shergottite meteorites, whereby LLE concentrations decrease dramatically from the cores to the rims, has been interpreted as being due to partitioning of LLE into a hydrous vapor during magma ascent to the surface on Mars. These trends are used as evidence that Martian basaltic melts are water-rich (McSween et al., 2001). Lithium and boron are light lithophile <span class="hlt">elements</span> (LLE) that partition into volcanic minerals and into vapor from silicate melts, making them potential tracers of degassing processes during magma ascent to the surface of <span class="hlt">Earth</span> and of other planets. While LLE degassing behavior is relatively well understood for silica-rich melts, where water and LLE concentrations are relatively high, very little data exists for LLE abundance, heterogeneity and degassing in basaltic melts. The lack of data hampers interpretation of the trends in the shergottite meteorites. Through a geochemical study of LLE, volatile and trace <span class="hlt">elements</span> in olivine-hosted melt inclusions from Kilauea Volcano, Hawaii, it can be demonstrated that lithium behaves similarly to the light to middle rare <span class="hlt">Earth</span> <span class="hlt">elements</span> during melting, magma mixing and fractionation. Considerable heterogeneity in lithium and boron is inherited from mantle-derived primary melts, which is dominant over the fractionation and degassing signal. Lithium and boron are only very weakly volatile in basaltic melt erupted from Kilauea Volcano, with vapor-melt partition coefficients <0.1. Degassing of LLE is further inhibited at high temperatures. Pyroxene and associated melt inclusion LLE concentrations from a range of volcanoes are used to quantify lithium pyroxene-melt partition coefficients, which correlate negatively with melt H2O content, ranging from 0.13 at low water contents to <0.08 at H2O contents >4 wt%. The observed terrestrial LLE partitioning behavior is extrapolated to Martian primitive melts through modeling. The zoning</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.1139F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.1139F"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of Intermediate Olivine-Phyric Shergottite Northwest Africa 6234</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Filiberto, J.; Chin, E.; Day, J. M. D.; Gross, J.; Penniston-Dorland, S. C.; Schwenzer, S. P.; Treiman, A. H.</p> <p>2012-03-01</p> <p>Here we present major- and trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span>, Li-isotope composition and abundance, and Re-Os isotope and highly siderophile <span class="hlt">element</span> abundance data for the ol-phyric shergottite Northwest Africa 6234.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6252376','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6252376"><span id="translatedtitle">Nuclear activation method and apparatus for detecting and quantifying <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>Carroll, J.F.</p> <p>1993-08-17</p> <p>A method is described for characterizing at least one activated <span class="hlt">element</span> in an <span class="hlt">earth</span> formation surrounding a borehole, comprising the steps of: (a) displacing in said borehole a sonde comprising a neutron source and at least two gamma ray detectors longitudinally spaced from said source, while irradiating said formation with neutrons of sufficient energy to interact with said <span class="hlt">element</span> according to the activation reaction; (b) detecting and counting at each detector the gamma rays resulting from the activation of atoms of said <span class="hlt">element</span>; (c) determining, at each depth, the number of gamma ray counts detected during the time period defined by the time instants when respectively said source and said detectors pass that depth, said determination of gamma ray counts being made for each detector at each depth; (d) establishing a relationship, for each depth, between the counts from the respective detectors for that depth and the corresponding time instants when the corresponding detector passes that depth; and (e) deriving from said relationship at least one characteristic of said <span class="hlt">element</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24657942','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24657942"><span id="translatedtitle">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="http://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)). PMID:24657942</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/2009CSR....29..896P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009CSR....29..896P"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in sediments of the Vigo Ria, NW Iberian Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Prego, Ricardo; Caetano, Miguel; Vale, Carlos; Marmolejo-Rodríguez, Judith</p> <p>2009-04-01</p> <p>The abundance and distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) and their signatures in the Vigo Ria were studied from 50 samples of surface sediments and related to the geological formation in its watershed. The total amount of REE in the Ria is heterogeneous. It ranges from 220 mg kg -1 in the southern middle Ria margin in the vicinity of the Galiñeiro geological shore complex, which contains REE-enriched minerals, to 2 mg kg -1 near the Ria mouth due to dilution with high levels of carbonated biogenic particles (31% of Ca). Rare <span class="hlt">earth</span> <span class="hlt">elements</span> of the Ria sediments are considerably enriched in light-REE relative to heavy-REE (a LREE/HREE ratio of 9.7±1.6) and also show a slightly negative Eu-anomaly. Low European shale normalised REE patterns were distinguished in the innermost sediments of Vigo Ria, but were not correlated with Al. This suggests a minor contribution of REE from upstream freshwater inputs to the sediments in the middle Vigo Ria zone. Normalised REE ratios in the middle Ria imply that fine particles enriched in REE may be exported from the Ria to shelf mud patches and REE can be useful as sediment tracers of Ria input on the shelf.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5798936','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5798936"><span id="translatedtitle">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/cgi-bin/nph-data_query?bibcode=2009GeCoA..73.1609B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009GeCoA..73.1609B&link_type=ABSTRACT"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/1999JChEd..76..475B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JChEd..76..475B"><span id="translatedtitle">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('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2584670','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2584670"><span id="translatedtitle">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://www.osti.gov/scitech/biblio/6997073','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6997073"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> distributions in recent and fossil apatite: implications for paleoceanography and stratigraphy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wright, J.</p> <p>1985-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) distributions in biogenic apatite were determined in over 200 samples from Cambrian to the Recent. Nondestructive instrumental neutron activation analysis techniques were adapted for analysis of low-mass microfossil samples. Tests for chemical contamination, interspecies, interlaboratory and interexperiment variations show that there is no fractionation of REE, so that ratios of rare <span class="hlt">earths</span> are consistent throughout the entire group of samples. The REE signature of biogenic apatite is acquired after deposition but only at the sediment-water interface and is characteristic of the redox state of the environment of deposition. This original environmental signature is retained through subsequent burial and diagenesis. Cerium has been shown to be the rare <span class="hlt">earth</span> <span class="hlt">element</span> that is sensitive to oxidation-reduction variations in marine waters. This cerium variation is stated mathematically and called Ce/sub anom/. Comparison of Ce/sub anom/ in fish debris from different modern redox environments shows that values > -0.10 occur in fish debris deposited under reducing conditions, whereas Ce/sub anom/ values <-0.10 are obtained under oxidizing conditions. Paleoredox studies of Ce/sub anom/ of fossil apatite of conodonts, fish debris and inarticulate brachiopods indicate that significant shifts in the overall redox balance of seawater occurred in ancient oceans. Cambrian through Silurian seas were dominated by anoxia, followed by a gradual change to oxidizing conditions in the Devonian. Oceans remained generally oxidizing throughout the Carboniferous and Lower Permian. In the Upper Permian and Lower Triassic anoxic conditions were again prevalent. This was followed by a return to an oxidizing oceanic environment in the Upper Triassic.</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 id="translatedtitle">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('http://hdl.handle.net/2060/19750007645','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750007645"><span id="translatedtitle"><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/2011MinDe..46..761D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011MinDe..46..761D"><span id="translatedtitle">Geology, <span class="hlt">geochemistry</span> and mineralogy of the lignite-hosted Ambassador palaeochannel uranium and multi-<span class="hlt">element</span> deposit, Gunbarrel Basin, Western Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Douglas, Grant B.; Butt, Charles R. M.; Gray, David J.</p> <p>2011-10-01</p> <p>The Ambassador U and multi-<span class="hlt">element</span> deposit occurs on the SW margin of the Gunbarrel Basin, Western Australia. Low-grade, flat-lying U mineralization averaging about 2 m thick at 0.03% U occurs in lignites at the redox front at the base of the weathering profile within a laterally extensive palaeochannel network. Uranium is principally associated with organic matter within the lignitic matrix, although rare discrete U minerals, such as coffinite and uraninite, are also present. The lignite is also enriched in a suite of other <span class="hlt">elements</span>, principally base metals and sulphur, with concentrations of 0.3 ≥ 1% Cu, Pb, Ni, Co, Zn and total rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in some samples. Other <span class="hlt">element</span> enrichments include: Cr, Cs, Sc, Se, Ta, Ti, Th, V and Zr as detrital heavy minerals of Zr, Ti and REE (oxides and silicates) or authigenic minerals of Cu, Bi, Pb, Zn, Ni, Se, Hg, Ti, Cr, Tl, V, U and REE (sulphides, vanadates, selenides, oxides, chlorides and native metals) and diffuse lignite impregnations. The Ambassador deposit probably formed from the convergence of redox-active weathering processes to unique source/host rocks, constrained within the palaeochannel. A proximal source of U and trace <span class="hlt">elements</span> of lamproite/carbonatite origin is probable, as constrained by U-Pb isotope and U-Th disequilibria studies. Uranium and other metals were precipitated syngenetically with organic matter as it was deposited during a humid phase in the Late Eocene. Remobilization subsequently concentrated the metals in the upper 2 m of the lignite. This may have occurred during one or more periods of weathering and associated diagenesis, with the latest episode in the last 300,000 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5244272','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5244272"><span id="translatedtitle"><span class="hlt">Geochemistry</span> and origin of regional dolomites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hanson, G.N.</p> <p>1984-01-01</p> <p>The objective is to develop quantitative, geochemical models for the source, flow-paths and chemistry of the diagenetic fluids responsible for the widespread dolomitization of the Mississippi Burlington-Keokuk Fms. In Iowa, Illinois and Missouri by integrating <span class="hlt">geochemistry</span>, fluid inclusion studies, conventional and luminescent petrography, stratigraphy, facies analysis and burial history. The original area of study has been significantly expanded and now includes western Illinois and eastern Missouri as well as southeastern Iowa. This includes most of the area where good sections of the Burlington-Keokuk Formations are exposed and almost the complete range of facies from near shore to the platform edge. Stratigraphic sections and depositional facies maps are being prepared for Illinois, Missouri and Iowa for Osagean time. The geochemical studies include: correlation of the major and trace <span class="hlt">element</span> variations within the various Burlington dolomites developed in southeastern Iowa and adjacent areas of Illinois and Missouri; rare <span class="hlt">earth</span> <span class="hlt">element</span>, Nd and Sr isotope analysis of the dolomites and coexisting phases; major and trace <span class="hlt">element</span> analysis, petrography and x-ray mineralogy of selected shaly members in the Burlington-Keokuk formations; and fluid inclusion studies of the calcites and dolomite cements of southeastern Iowa. 8 figures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25278442','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25278442"><span id="translatedtitle">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="http://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. PMID:25278442</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015FrEaS...3....6H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015FrEaS...3....6H"><span id="translatedtitle">Assessing the utility of trace and rare <span class="hlt">earth</span> <span class="hlt">elements</span> as biosignatures in microbial iron oxyhydroxides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heim, Christine; Simon, Klaus; Ionescu, Danny; Reimer, Andreas; De Beer, Dirk; Quéric, Nadia-Valérie; Reitner, Joachim; Thiel, Volker</p> <p>2015-02-01</p> <p>Microbial iron oxyhydroxides are common deposits in natural waters, recent sediments and mine drainage systems and often contain significant accumulations of trace and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (TREE). TREE patterns are widely used to characterize minerals and rocks, and to elucidate their evolution and origin. Whether and which characteristic TREE signatures distinguish between a biological and an abiological origin of iron minerals is still not well understood. Long-term flow reactor studies were performed in the Äspö Hard Rock Laboratory to investigate the development of microbial mats dominated by iron-oxidizing bacteria, namely Mariprofundus sp. and Gallionella sp. The experiments investigated the accumulation and fractionation of TREE under controlled conditions and enabled us to assess potential biosignatures evolving within the microbial iron oxyhydroxides. Concentrations of Be, Y, Zn, Zr, Hf, W, Th, Pb, and U in the microbial mats were 1e3- to 1e5-fold higher than in the feeder fluids whereas the rare <span class="hlt">earth</span> <span class="hlt">elements</span> and Y (REE+Y) contents were 1e4 and 1e6 fold enriched. Except for a hydrothermally induced Eu anomaly, the normalized REE+Y patterns of the microbial iron oxyhydroxides were very similar to published REE+Y distributions of Archaean Banded Iron Formations. The microbial iron oxyhydroxides from the flow reactors were compared to iron oxyhydroxides that were artificially precipitated from the same feeder fluid. These abiotic and inorganic iron oxyhydroxides show the same REE+Y distribution patterns. Our results indicate that the REE+Y mirror quite exactly the water chemistry, but they do not allow to distinguish microbially mediated from inorganic iron precipitates. All TREE studied showed an overall similar fractionation behavior in biogenic, abiotic and inorganic iron oxyhydroxides. Exceptions are Ni and Tl, which were only accumulated in the microbial iron oxyhydroxides and may point to a potential usage of these <span class="hlt">elements</span> as microbial biosignatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26515437','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26515437"><span id="translatedtitle">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="http://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. PMID:26515437</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870038811&hterms=Cerium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCerium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870038811&hterms=Cerium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCerium"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/18329796','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18329796"><span id="translatedtitle">Chemical properties of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in typical medical waste incinerator ashes in China.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Lijuan; Zhang, Fu-Shen; Zhang, Jingxin</p> <p>2008-10-30</p> <p>Medical waste (MW) ashes from different types of MW incinerators were examined to detect the characteristics and environmental impact of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs). The results showed that total REE contents in the ash samples ranged from 10.2 to 78.9 mg/kg. REEs in bottom ash were apparently higher than those in fly ash. Average REE contents in the ashes followed the sequence of Ce>La>Nd>Y>Gd>Pr>Sm>Dy>Er>Yb>Ho>Eu>Tb>Lu>Tm. Some of the <span class="hlt">elements</span>, such as Sm, Dy, Ho, Er, Yb in the ash samples were in normal or nearly normal distribution, but Y, La, Ce, Pr, Nd, Eu, Gd, Tb, Tm, Lu were not normally distributed, indicating some of the ash samples were enriched with these <span class="hlt">elements</span>. Crust-normalized REE patterns indicated that two types of the MW ashes were obviously enriched with Gd and La. Sequential extraction results showed that REEs in the ash mainly presented as residual fraction, while exchangeable and carbonate fractions were relatively low. DTPA- and EDTA-extraction tests indicated that REEs in the MW ashes were generally in low bioavailability. PMID:18329796</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 id="translatedtitle">'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('http://adsabs.harvard.edu/abs/2013GeCoA.108...63P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.108...63P"><span id="translatedtitle">Insights into early <span class="hlt">Earth</span> from Barberton komatiites: Evidence from lithophile isotope and trace <span class="hlt">element</span> systematics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Puchtel, I. S.; Blichert-Toft, J.; Touboul, M.; Walker, R. J.; Byerly, G. R.; Nisbet, E. G.; Anhaeusser, C. R.</p> <p>2013-05-01</p> <p>Major, minor, and lithophile trace <span class="hlt">element</span> abundances and Nd and Hf isotope systematics are reported for two sets of remarkably fresh, by Archean standards, samples of komatiitic lavas from the 3.48 Ga Komati and the 3.27 Ga Weltevreden Formations of the Barberton Greenstone Belt (BGB) in South Africa. These data are used to place new constraints on the thermal history of the early Archean mantle, on the timing of its differentiation, and on the origin and chemical nature of early mantle reservoirs and their evolution through time. Projected moderate to strong depletions of highly incompatible lithophile trace <span class="hlt">elements</span> and water in the mantle sources of both komatiite systems, combined with the partitioning behavior of V during lava differentiation, are consistent with anhydrous conditions during generation of the komatiite magmas. Komati and Weltevreden lavas are inferred to have erupted with temperatures of ∼1600 °C, and, thus, represent the hottest known lavas on <span class="hlt">Earth</span>. The calculated mantle potential temperatures of ∼1800 °C for both komatiite systems are 150-200 °C higher than those of contemporary ambient mantle. Combined, these observations are consistent with the origin of these BGB komatiite magmas in mantle plumes in the lower mantle. New Sm-Nd and Lu-Hf isotopic data allow precise determination of initial ε143Nd = +0.46 ± 0.10 and +0.50 ± 0.11 and initial ε176Hf = +1.9 ± 0.3 and +4.7 ± 0.8 for the Komati and the Weltevreden system komatiites, respectively. These positive initial values reflect prior fractionation of Sm/Nd and Lu/Hf in the mantle early in <span class="hlt">Earth</span> history. Conversely, μ142Nd values are 0.0 ± 2.4 and +2.2 ± 4.1 for the Komati and the Weltevreden systems, respectively. These values overlap, within uncertainties, those of modern terrestrial rocks, thus, limiting the magnitudes of possible Sm/Nd fractionations generated by early <span class="hlt">Earth</span> processes in the sources of these rocks. Combined 142,143Nd and Hf isotope and lithophile trace</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AtmEn..44.2563M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AtmEn..44.2563M&link_type=ABSTRACT"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2011AGUFM.V43B2572L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V43B2572L"><span id="translatedtitle">Evolution and timing of tectonic events in the Arabia-Eurasia convergence zone as inferred from igneous <span class="hlt">geochemistry</span> from the <span class="hlt">Earth</span>Chem database</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lieu, W. K.; Stern, R. J.</p> <p>2011-12-01</p> <p>The timing of tectonic events in the Anatolia-Iranian region can be inferred from analysis of igneous rocks. Magmatic activities in the region are generally associated with the convergence of the African-Arabian and Eurasian plates and the subduction of the Neotethys Ocean. Ancillary processes such as subduction of continental crust, delamination of upper plate lithosphere or lower crust, or asthenospheric decompression accompanying post-collisional relaxation also contribute to the composition of igneous rocks. Here we use geochemical data gathered from the <span class="hlt">Earth</span>Chem database to assess broad chemical implications of Cenozoic tectonic activities of the convergence region. We search for geochemical signal of the timing of first contact of the subducting Arabian and overriding Eurasian continental crust. Of particular interest is how igneous rock compositions vary during the transition from pre- to post-contact of the continental crusts. Also, is there a geographic variation along the convergence zone during this tectonic transition? We generate maps and geochemical plots for four different epochs and two different regions since Cenozoic time: Iran and Anatolia in the Eocene, Oligocene, Miocene and Plio-Quaternary. This board, region-scaled analysis of major and trace <span class="hlt">element</span> patterns suggests the following tectonic events: Subduction-related medium K calc-alkaline igneous rocks reflect Eocene subduction of the Neo-Tethys oceanic lithosphere. Oligocene igneous rocks are characterized by K2O-SiO2 trends scattering to higher silica and alkaline content, which may reflect subduction of stretched continental margin lithosphere and sediments. A bimodal pattern of potash-silica trends during Miocene time may mark the transition from subduction-related to intra-plate magmatism, perhaps signaling contact between the continental crust of Arabia-Africa with Eurasia. Pliocene and younger igneous rocks show an intra-plate and ocean island basalt trend, as the region's activities</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50.1624J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50.1624J"><span id="translatedtitle">The formation conditions of enstatite chondrites: Insights from trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of olivine-bearing chondrules in Sahara 97096 (EH3)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jacquet, Emmanuel; Alard, Olivier; Gounelle, Matthieu</p> <p>2015-09-01</p> <p>We report in situ LA-ICP-MS trace <span class="hlt">element</span> analyses of silicate phases in olivine-bearing chondrules in the Sahara 97096 (EH3) enstatite chondrite. Most olivine and enstatite present rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns comparable to their counterparts in type I chondrules in ordinary chondrites. They thus likely share a similar igneous origin, likely under similar redox conditions. The mesostasis however frequently shows negative Eu and/or Yb (and more rarely Sm) anomalies, evidently out of equilibrium with olivine and enstatite. We suggest that this reflects crystallization of oldhamite during a sulfidation event, already inferred by others, during which the mesostasis was molten, where the complementary positive Eu and Yb anomalies exhibited by oldhamite would have possibly arisen due to a divalent state of these <span class="hlt">elements</span>. Much of this igneous oldhamite would have been expelled from the chondrules, presumably by inertial acceleration or surface tension effects, and would have contributed to the high abundance of opaque nodules found outside them in EH chondrites. In two chondrules, olivine and enstatite exhibit negatively sloped REE patterns, which may be an extreme manifestation of a general phenomenon (possibly linked to near-liquidus partitioning) underlying the overabundance of light REE observed in most chondrule silicates relative to equilibrium predictions. The silicate phases in one of these two chondrules show complementary Eu, Yb, and Sm anomalies providing direct evidence for the postulated occurrence of the divalent state for these <span class="hlt">elements</span> at some stage in the formation reservoir of enstatite chondrites. Our work supports the idea that the peculiarities of enstatite chondrites may not require a condensation sequence at high C/O ratios as has long been believed.</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('http://pubs.er.usgs.gov/publication/70018161','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018161"><span id="translatedtitle">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://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="http://ntrs.nasa.gov/search.jsp?R=19860050790&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DPeridotite"><span id="translatedtitle">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://ntrs.nasa.gov/search.jsp?R=19750027184&hterms=ionic+liquid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dionic%2Bliquid','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750027184&hterms=ionic+liquid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dionic%2Bliquid"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2015AIPC.1702s0004G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPC.1702s0004G"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/25818140','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25818140"><span id="translatedtitle">Spectrophotometric determination of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in aqueous nitric acid solutions for process control.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rodionova, Oxana Ye; Tikhomirova, Tatyana I; Pomerantsev, Alexey L</p> <p>2015-04-15</p> <p>Noninvasive analytical control is of special interest for the complicated and hazardous production processes. On-line monitoring provides a unique opportunity to determine critical concentrations rapidly and without serious risks to operating personnel and the environment. Models for quantitative determination of concentrations of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in complex mixtures in nitric acid serve for these purposes. Here, the feasibility of simultaneous determination of cerium, praseodymium, and neodymium using the whole UV-vis spectroscopic range, together with chemometric data processing, is studied. The predictability of two chemometric techniques, partial least squares regression and correlation constrained multivariate curve resolution-alternating least squares are compared. Models' performances are analyzed in out-of-control cases. PMID:25818140</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984Metic..19...69E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984Metic..19...69E"><span id="translatedtitle">Distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and uranium in various components of ordinary chondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ebihara, M.; Honda, M.</p> <p>1984-06-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) and uranium were studied for their distributions in various component phases of four ordinary chondrites. Kesen (H4), Richardton (H5), Bruderheim (L6), and Saint Severin (LL6). A selective dissolution method was applied for the phase fractionation. The REE were analysed by neutron activation analysis, and U was determined by neutron-induced fission tracks. The present study revealed that both REE and U are highly enriched in the Ca-phosphate minerals with different enrichment factors, implying chemical fractionation between them. The phosphates seem to be responsible for more than 80 percent of the light REE in all chondrites. On the other hand, only 20-40 percent of the total U resides in the Ca-phosphates. This difference in enrichments might have been caused through the levels of metamorphic activity on the meteoritic parent bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22499193','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22499193"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2015CRGeo.347..294H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CRGeo.347..294H"><span id="translatedtitle">Anthropogenic rare <span class="hlt">earth</span> <span class="hlt">element</span> fluxes into floodplains: Coupling between geochemical monitoring and hydrodynamic sediment transport modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hissler, Christophe; Hostache, Renaud; Iffly, Jean François; Pfister, Laurent; Stille, Peter</p> <p>2015-09-01</p> <p>As all rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have an increasingly important role in high tech industries, they are now recognized as emergent pollutants in river systems impacted by anthropogenic activity. Over the past 20 years, significant anthropogenic contributions were reported for Gd, La and Sm, and we may expect that REE contamination in rivers is to further increase in a near future. Despite the work done to assess the environmental impact of REE pollutions in larger river systems, we are still lacking information on the dynamics of these anthropogenic compounds in relation to hydrological changes. Here, we observed for the first time particulate Ce originating from local industrial activities in Luxembourg and we quantified the anthropogenic contribution to the REE fluxes at the river basin scale during a single flood event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22492828','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22492828"><span id="translatedtitle">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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AcGeo..61..876S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AcGeo..61..876S&link_type=ABSTRACT"><span id="translatedtitle">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('http://www.osti.gov/scitech/servlets/purl/792697','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/792697"><span id="translatedtitle">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('http://www.osti.gov/scitech/biblio/22257887','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22257887"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/23102343','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23102343"><span id="translatedtitle">Site-selective Mott transition in rare-<span class="hlt">earth-element</span> nickelates.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Hyowon; Millis, Andrew J; Marianetti, Chris A</p> <p>2012-10-12</p> <p>A combination of density functional and dynamical mean field theory calculations are used to show that the remarkable metal-insulator transition in the rare-<span class="hlt">earth-element</span> nickelate perovskites arises from a site-selective Mott phase, in which the d electrons on half of the Ni ions are localized to form a fluctuating moment while the d electrons on other Ni ions form a singlet with holes on the surrounding oxygen ions. The calculation reproduces key features observed in the nickelate materials, including an insulating gap in the paramagnetic state, a strong variation of static magnetic moments among Ni sites and an absence of charge order. A connection between structure and insulating behavior is documented. The site-selective Mott transition may be a more broadly applicable concept in the description of correlated materials. PMID:23102343</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16038502','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16038502"><span id="translatedtitle">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="http://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. PMID:16038502</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1251424-bioadsorption-rare-earth-elements-through-cell-surface-display-lanthanide-binding-tags','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1251424-bioadsorption-rare-earth-elements-through-cell-surface-display-lanthanide-binding-tags"><span id="translatedtitle">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 PAGESBeta</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 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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900012568','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900012568"><span id="translatedtitle">Galileo <span class="hlt">Earth</span> approach navigation using connected-<span class="hlt">element</span> interferometer phase-delay tracking</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thurman, S. W.</p> <p>1990-01-01</p> <p>The application of a Connected-<span class="hlt">Element</span> Interferometer (CEI) to the navigation of the Galileo spacecraft during its encounter with <span class="hlt">Earth</span> in December 1990 is investigated. A CEI tracking demonstration is planned for the week of November 11 through 18, 1990, from 27 days to 20 days prior to <span class="hlt">Earth</span> encounter on December 8. During this period, the spacecraft will be tracked daily with Deep Space Network Stations 13 and 15 at Goldstone. The purpose of this work is twofold: first, to establish and define the navigation performance expected during the tracking demonstration and, second, to study, in a more general sense, the sensitivity of orbit demonstration results obtained with CEI to the data density within CEI tracking passes and to important system parameters, such as baseline orientation errors and the phase-delay measurement accuracy. Computer simulation results indicate that the use of CEI data, coupled with conventional range and Doppler data, may reduce the uncertainty in the declination of the spacecraft's incoming trajectory by 15 to 66 percent compared with the operational solution using range and Doppler data only. The level of improvement depends upon the quantity and quality of the CEI data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26836847','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26836847"><span id="translatedtitle">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.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. PMID:26836847</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 id="translatedtitle">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('http://adsabs.harvard.edu/abs/2014MinDe.tmp...43S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MinDe.tmp...43S"><span id="translatedtitle">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>2014-09-01</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('http://www.ncbi.nlm.nih.gov/pubmed/21324705','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21324705"><span id="translatedtitle">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="http://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. PMID:21324705</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://pubs.er.usgs.gov/publication/70044201','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70044201"><span id="translatedtitle">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 id="translatedtitle">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('http://www.osti.gov/scitech/biblio/22337283','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22337283"><span id="translatedtitle">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="http://www.osti.gov/scitech">SciTech Connect</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 (PM{sub 10}) were collected around the Bayan Obo mine region, in August 2012 and March 2013, to analyze the levels and distributions of REEs in particles. The total concentrations of REEs for TSP were 149.8 and 239.6 ng/m{sup 3}, and those for PM{sub 10} were 42.8 and 68.9 ng/m{sup 3}, in August 2012 and March 2013, respectively. Enrichment factor was calculated for all 14 REEs in the TSP and PM{sub 10} and the results indicated that REEs enrichment in atmosphere particulates was caused by anthropogenic sources and influenced by the strong wind in springtime. The spatial distribution of REEs in TSP showed a strong gradient concentration in the prevailing wind direction. REE chondrite normalized patterns of TSP and PM{sub 10} were similar and the normalized curves inclined to the right side, showing the conspicuous fractionation between the light REEs and heavy REE, which supported by the chondrite normalized concentration ratios calculated for selected <span class="hlt">elements</span> (La{sub N}/Yb{sub N}, La{sub N}/Sm{sub N}, Gd{sub N}/Yb{sub N}). - Highlights: • TSP and PM{sub 10} samples were collected to analyze the levels and distributions of REE. • Enrichment factors indicated that REE enrichment was caused by anthropogenic sources. • The distribution of REEs showed a strong gradient in the prevailing wind direction. • Obvious fractionation between LREEs and HREEs is observed in atmospheric particulates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70039454','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70039454"><span id="translatedtitle"><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>U.S. Geological Survey</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OptMa..52...32D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OptMa..52...32D"><span id="translatedtitle">Performance evaluation of Laser Induced Breakdown Spectroscopy (LIBS) for quantitative analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in phosphate glasses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Devangad, Praveen; Unnikrishnan, V. K.; Nayak, Rajesh; Tamboli, M. M.; Muhammed Shameem, K. M.; Santhosh, C.; Kumar, G. A.; Sardar, D. K.</p> <p>2016-02-01</p> <p>In the current study, we have determined the <span class="hlt">elemental</span> compositions of synthesized rare <span class="hlt">earth</span> doped phosphate glasses using a laboratory Laser-Induced Breakdown Spectroscopy (LIBS) system. LIBS spectra of this rare <span class="hlt">earth</span> (samarium (Sm), thulium (Tm) and ytterbium (Yb)) doped glass samples with known composition are recorded using a highly sensitive detector. Major atomic emission lines of Sm, Tm and Yb found in LIBS spectra are reported. By considering the atomic emission line of phosphorous as an internal standard, calibration curves were constructed for all the rare <span class="hlt">earth</span> concentrations. Very good linear regression coefficient (R2) values were obtained using this technique. Analytical predictive skill of LIBS was studied further using leave-one-out method. Low values of the reported correlation uncertainty between measured LIBS concentration ratio and certified concentration ratio confirms that LIBS technique has great potential for quantitative analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in glass matrix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990igc..book.....S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990igc..book.....S"><span id="translatedtitle">Isotopic <span class="hlt">geochemistry</span> and cosmochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shchukoliukov, Iu. A.</p> <p></p> <p>The book includes recent information on isotope geology, <span class="hlt">geochemistry</span>, and cosmochemistry, discussed at a recent Soviet-Japanese symposium (at Irkutsk, USSR). Attention is given to numerical modeling of geochronometric systems, a classification of noble-gas components in the <span class="hlt">earth</span>'s interior, the feasibility of using ion microprobe for local isotope analysis of zircons for the purpose of deriving the early history of the <span class="hlt">earth</span> (on the example of the Novopavlovsk complex from the Ukranian shield), a geological and geochronological study of the Ganalski complex of Kamchatka, and strontium isotopes as a criterion of the nature of acid melts (i.e., mantle- or crust-related). Other papers are on the geochronology and geology of Siberian kimberlites, the nature of sulfur from effusive rocks of the Kamchatka-Kuril-Japan island arc, mass-spectrometric studies of volatile components in exocontact rocks of alkaline-basic intrusions, and an analytical method for stable-isotope analysis in ultrasmall amounts of CO2 and its application to studies of the microscale isotopic zoning in calcite and graphite crystals in marble.</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 id="translatedtitle">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/cgi-bin/nph-data_query?bibcode=2016Litho.248..432F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.248..432F&link_type=ABSTRACT"><span id="translatedtitle">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/2001AGUFM.H41A0270D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.H41A0270D"><span id="translatedtitle">Key Factors Controlling Space- and Time-Linked Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Distribution in Shallow Groundwaters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dia, A.; Gruau, G.; Olivie-Lauquet, G.; Henin, O.; Petitjean, P.; Le Coz-Bouhnik, M.</p> <p>2001-12-01</p> <p>This study investigates the effects of source-rock composition, redox changes and organic matter on the hydrochemistry of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE). Wetland groundwater samples as well as upland zone water samples were recovered weekly over a six month period (January to June 1999) from a small catchment (Petit Hermitage, France). The samples were filtered on the field using membrane filters of 0.22 μ m pore size, and then analyzed for their Dissolved Organic Carbon (DOC) as well as Fe, Mn, Al, Th, U and REE concentrations. The results are discussed in conjunction with previous published DOC and trace-<span class="hlt">element</span> concentrations obtained on comparable samples from three other small catchments, namely : the Nsimi-Zoetele, Goyoum (both in Cameroon) and Kervidy/Coet-Dan (France) catchments (Viers et al., 1997; Braun et al., 1998; Dia et al., 2000). Despite marked differences (such as bioclimatic conditions, vegetation cover, basement rock composition or human activity), results are surprisingly similar with always the occurrence of two spatially distinct groundwater types including : (i) a shallow, organic-rich groundwater below wetlands recording high and variable REE contents and displaying slight or no negative Ce anomaly. In the wetland groundwaters, the REE and other trace-<span class="hlt">element</span> concentrations seem to be controlled by seasonal dynamics, involving both temperature, whose onset at spring leads to higher organic carbon decomposition rates by microbial mass, and redox changes resulting in REE and other-trace <span class="hlt">element</span> release in water when mineral phases occur to dissolve. (ii) The second groundwater type corresponds to a shallow, organic-poor groundwater type located below the hillslope domains. This second groundwater type displays lower REE (and other trace-<span class="hlt">element</span>) concentrations, but distinguish from the former by the occurrence of very strong negative Ce anomalies, whose amplitude is variable, but appears to be linked to the sampling location along the catena. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPA....6e6019B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPA....6e6019B"><span id="translatedtitle">Substitution of Nd with other rare <span class="hlt">earth</span> <span class="hlt">elements</span> in melt spun Nd2Fe14B magnets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brown, D. N.; Lau, D.; Chen, Z.</p> <p>2016-05-01</p> <p>This is a contemporary study of rapidly quenched Nd1.6X0.4Fe14B magnetic materials (where X= Nd, Y, Ce, La, Pr, Gd and Ho). A 20% substitution of the Nd component from Nd2Fe14B can bring about some commercial advantage. However, there will be some compromise to the magnetic performance. Light rare <span class="hlt">earth</span> <span class="hlt">elements</span> are definitely more abundant (Y, Ce, La) than the heavier rare <span class="hlt">earth</span> <span class="hlt">elements</span>, but when they are included in RE2Fe14B magnets they tend to lower magnetic performance and thermal stability. Substituting heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> (Gd, Ho) for Nd in Nd2Fe14B improves the thermal stability of magnets but causes a loss in magnet remanence.</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 id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/27447714','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27447714"><span id="translatedtitle">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="http://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. PMID:27447714</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2593843','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2593843"><span id="translatedtitle">Biosorption of Uranium and Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Using Biomass of Algae</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sakamoto, Nobuo; Kano, Naoki; Imaizumi, Hiroshi</p> <p>2008-01-01</p> <p>In order to investigate the behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and uranium (U) in marine organism, the concentrations of REEs and U in some brown algae samples taken on the coast of Niigata Prefecture were determined. In addition, laboratory model experiment to uptake these <span class="hlt">elements</span> using living and dried algae (Undaria pinnatifida and Sargassum hemiphyllum) was also carried out to survey the uptake and bioaccumulation mechanism of REEs and U in algae. Consequently, the following matters have been mainly clarified. (1) The order of the concentration of REEs for each organ in Sargassum hemiphyllum is “main branch” > “leaf” > “vesicle,” however for U, the order is “leaf” > “vesicle” > “main branch.” (2) The concentration of REEs in Sargassum hemiphyllum may be strongly affected by suspended solid in seawater. (3) The uptake and/or accumulate mechanism of REEs in brown algae may be different from that of U. PMID:19081786</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4393457','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4393457"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2016NIMPB.366..184C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NIMPB.366..184C"><span id="translatedtitle">Study of Kα2 /Kα1 RYIED in closed and open shell 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>Chaves, P. C.; Tribolet, A. D.; Reis, M. A.</p> <p>2016-01-01</p> <p>Relative Yield Ion Energy Dependence (RYIED) was observed, named and reported as phenomenological evidence in 2005 (Reis et al., 2005). Since then, it was observed in transitions to the same subshell, and plausible explanations for the physics behind the phenomena have been proposed. In this work we present experimental evidence of the RYIED effect on the most inner transition possible in two Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE), namely variations in the intensity ratio of Kα2 /Kα1 X-rays from Tm and Yb irradiated under different conditions. These REE are particularly interesting to start with since Yb has an electronic configuration where all the subshells are completely filled, whilst Tm misses one electron in the 4f subshell. Ultrapure oxides of each <span class="hlt">element</span> were irradiated using proton beams having energies in the range of 0.9-3.6 MeV, in steps of 100 keV. Spectra were collected using the CdTe detector of the HRHE-PIXE set-up of C2TN and analysed using the DT2 code. Finally, the vanishing of the effect upon charging up of the target has been observed and will be discussed.</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 id="translatedtitle">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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009EGUGA..1112002M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009EGUGA..1112002M&link_type=ABSTRACT"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2010CoMP..160..761O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010CoMP..160..761O"><span id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/23978671','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23978671"><span id="translatedtitle">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="http://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. PMID:23978671</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27451177','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27451177"><span id="translatedtitle">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="http://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. PMID:27451177</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://www.ncbi.nlm.nih.gov/pubmed/23150591','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23150591"><span id="translatedtitle">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="http://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. PMID:23150591</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeCoA..74.6690T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeCoA..74.6690T"><span id="translatedtitle">Ligand extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> from aquifer sediments: Implications for rare <span class="hlt">earth</span> <span class="hlt">element</span> complexation with organic matter in natural waters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tang, Jianwu; Johannesson, Karen H.</p> <p>2010-12-01</p> <p>The ability of organic matter as well as carbonate ions to extract rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) from sandy sediments of a Coastal Plain aquifer was investigated for unpurified organic matter from different sources (i.e., Mississippi River natural organic matter, Aldrich humic acid, Nordic aquatic fulvic acid, Suwannee River fulvic acid, and Suwannee River natural organic matter) and for extraction solutions containing weak (i.e., CH 3COO -) or strong (i.e., CO32-) ligands. The experimental results indicate that, in the absence of strong REE complexing ligands in solution, the amount of REEs released from the sand is small and the fractionation pattern of the released REEs appears to be controlled by the surface stability constants for REE sorption with Fe(III) oxides/oxyhydroxides. In the presence of strong solution complexing ligands, however, the amount and the fractionation pattern of the released REEs reflect the strength and variation of the stability constants of the dominant aqueous REE species across the REE series. The varying amount of REEs extracted by the different organic matter employed in the experiments indicates that organic matter from different sources has different complexing capacity for REEs. However, the fractionation pattern of REEs extracted by the various organic matter used in our experiments is remarkable consistent, being independent of the source and the concentration of organic matter used, as well as solution pH. Because natural aquifer sand and unpurified organic matter were used in our experiments, our experimental conditions are more broadly similar to natural systems than many previous laboratory experiments of REE-humic complexation that employed purified humic substances. Our results suggest that the REE loading effect on REE-humic complexation is negligible in natural waters as more abundant metal cations (e.g., Fe, Al) out-compete REEs for strong binding sites on organic matter. More specifically, our results indicate that REE</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22472534','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22472534"><span id="translatedtitle">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/2014E%26PSL.398..101T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.398..101T"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2014EGUGA..1615804M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1615804M"><span id="translatedtitle">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('http://www.osti.gov/scitech/servlets/purl/1191943','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1191943"><span id="translatedtitle">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/pages/biblio/1191943-utilizing-rare-earth-elements-tracers-high-tds-reservoir-brines-ccs-applications','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1191943-utilizing-rare-earth-elements-tracers-high-tds-reservoir-brines-ccs-applications"><span id="translatedtitle">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 PAGESBeta</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/1261974','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1261974"><span id="translatedtitle">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/Publications.htm?seq_no_115=271700','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=271700"><span id="translatedtitle">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://adsabs.harvard.edu/abs/2004GeoJI.158..401W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004GeoJI.158..401W"><span id="translatedtitle">Using commercial finite <span class="hlt">element</span> packages for the study of <span class="hlt">earth</span> deformations, sea levels and the state of stress</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Patrick</p> <p>2004-08-01</p> <p>Modifications to commercial finite <span class="hlt">element</span> (FE) packages must be applied before they can be used for geophysical studies involving long wavelength deformation or viscoelasticity. This paper provides in detail how and why the commercial codes have to be modified when incompressibility is assumed. Both the non-self-gravitating flat <span class="hlt">earth</span> and self-gravitating spherical <span class="hlt">earth</span> will be considered. The latter involves an iterative procedure, which converges within 5 iterations. This is demonstrated both analytically and numerically. In addition, implementation of the gravitationally self-consistent sea level equation on a self-gravitating spherical <span class="hlt">earth</span> is also described. Good agreement between numerical results obtained with this coupled finite-<span class="hlt">element</span> method and the conventional spectral method is also demonstrated. In all cases, the interpretation of the outputs of FE models are particularly important in modelling the state of stress.</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 id="translatedtitle">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., Jr.; 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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25679485','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25679485"><span id="translatedtitle">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="http://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. PMID:25679485</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 id="translatedtitle">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('http://www.ncbi.nlm.nih.gov/pubmed/27228215','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27228215"><span id="translatedtitle">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="http://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>2016-06-01</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. PMID:27228215</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T33A0520H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T33A0520H"><span id="translatedtitle">Insights of ridge-flank hydrothermal processes through minor and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of sediment pore fluids from IODP Site 1301</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hulme, S. M.</p> <p>2005-12-01</p> <p>The volumetric flux of seawater that flows through the oceanic crust rivals that which flows from rivers into the oceans. As seawater or formation fluid circulates through oceanic basement it is warmed and reacts with basalt and secondary minerals. In addition, diffusive exchange with overlying pore fluids may also impact the composition of the circulating fluid in basement. This interplay among seawater (formation fluid) reaction with basalt, diffusive exchange, and warming continues to the point of egress. How this seawater circulates through the crust and the chemical, mass, and thermal fluxes that it generates was the focus for drilling IODP Leg 301 on the eastern flank of the Juan de Fuca Ridge on 3.5-m.y.-old crust. We have conducted a comprehensive series of chemical analyses on pore waters from IODP Expedition 301 to constrain the composition of the formation fluid within the upper-most basaltic basement and compared it to the composition from nearby springs and borehole data. Sediments were recovered from IODP Holes 1301C (29 samples) and 1301D (9 samples) using the advanced piston coring (APC) technique. Sediments for pore fluid extraction were collected throughout the sediment column with a greater vertical resolution at the sediment-basement contact. Pore fluids were extracted in a nitrogen atmosphere to minimize potential oxidation reactions. Shipboard analyses included Ca, Mg, Alkalinity, pH, chlorinity, ammonium, phosphate, sulfate, K, Si, Li, B, Mn, Fe, Sr, DIC, total C, and Ba. Subsequent sample analysis with a Finnagin <span class="hlt">Element</span> 2 high-resolution ICP-MS included: the trace <span class="hlt">elements</span> Rb, Cs, Ba, Y, Cd and U; transition metals Mo, V, Cr, Co, Cu, Ni and Zn; and the complete suite of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE). These data provide additional constraints to determine diffusive fluxes between the sediment and basement reservoirs, allowing us to refine models that constrain the rate of fluid flow within the crust and re-affirm the directionality of flow along</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..1710235D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..1710235D&link_type=ABSTRACT"><span id="translatedtitle">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/2003TrGeo...5..425C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003TrGeo...5..425C"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of Groundwater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chapelle, F. H.</p> <p>2003-12-01</p> <p>Differentiation of terrestrial planets includes separation of a metallic core and possible later fractionation of mineral phases within either a solid or molten mantle (Figure 1). Lithophile and siderophile <span class="hlt">elements</span> can be used to understand these two different physical processes, and ascertain whether they operated in the early <span class="hlt">Earth</span>. The distribution of <span class="hlt">elements</span> in planets can be understood by measuring the partition coefficient, D (ratio of concentrations of an <span class="hlt">element</span> in different phases (minerals, metals, or melts)). (14K)Figure 1. Schematic cross-section through the <span class="hlt">Earth</span>, showing: (a) an early magma ocean stage and (b) a later cool and differentiated stage. The siderophile <span class="hlt">elements</span> (iron-loving) encompass over 30 <span class="hlt">elements</span> and are defined as those <span class="hlt">elements</span> for which D(metal/silicate)>1, and are useful for deciphering the details of core formation. This group of <span class="hlt">elements</span> is commonly broken up into several subclasses, including the slightly siderophile <span class="hlt">elements</span> (1<D<10), moderately siderophile <span class="hlt">elements</span> (MSEs; 10<D<104), and highly siderophile <span class="hlt">elements</span> (HSEs; D>104). Because these three groups encompass a wide range of partition coefficient values, they can be very useful in trying to determine the conditions under which metal may have equilibrated with the mantle (or a magma ocean). Because metal and silicate may equilibrate by several different mechanisms, such as at the base of a deep magma ocean, or as metal droplets descend through a molten mantle, partition coefficients can potentially shed light on which mechanism may be most important, thus linking the physics and chemistry of core formation. In this chapter, we summarize metal/silicate partitioning of siderophile <span class="hlt">elements</span> and show how they may be used to understand planetary core formation.Once a planet is differentiated into core and mantle, a mantle will cool during convection, and can start in either a molten or solid state, depending upon the initial thermal conditions. If hot enough, minerals will</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990E%26PSL.100....1B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990E%26PSL.100....1B"><span id="translatedtitle">Nd, Sr-isotopic provenance and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of Amazonian foreland basin fluvial sands, Bolivia and Peru: implications for ensialic Andean orogeny</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Basu, Asish R.; Sharma, Mukul; DeCelles, Peter G.</p> <p>1990-10-01</p> <p>Nd and Sr isotopes and the trace <span class="hlt">element</span> contents, including the rare <span class="hlt">earths</span>, were determined for fluvial sands of lithic arenite composition from the Madre de Dios foreland basin of Bolivia and Peru. On standard petrologic ternary diagrams, the sands fall in the recycled orogen provenance field and thus are similar to typical ancient foreland basin composition. The average rare <span class="hlt">earth</span> <span class="hlt">elemental</span> pattern of the sands is identical to the upper continental crustal average, as estimated from post-Archean composite shales of different continents. Ratios ofTh/U, Co/Th, La/Sc and Th/Sc of the fluvial sands are intermediate between an average magmatic arc and an upper crustal average compositions. The dispersion of some trace <span class="hlt">elemental</span> patterns in the sands can be attributed to fractionation of dense minerals, including zircon, during the sedimentation process. The variations of Nd isotopes in conjunction with the petrographic parameters of lithic metamorphic (Lm) and volcanic (Lv) fragments allow a two-fold classification of the sands. These two sand types can be interpreted in terms of mixing among three different provenances: one volcanic rock-suite with less negativeɛ Nd(O) parameter than the other volcanic suite, and a third metasedimentary source withɛ Nd(O) value of around -12, which is considered to be similar to the average western Brazilian shield composition. Thus the overall compositions of the sands has been modeled as mechanical mixtures of two components, an Andean magmatic arc and the Brazilian shield-derived metasediments. The model is strongly supported by a plot ofɛ Nd(O) versusɛ Sr(O) of the sands. In this plot, the Type 1 and 2 sands define two coherent hyperbolic trends contiguous with two different portions of the Andean magmatic trend. This relationship has been interpreted to indicate that the observed Andean magmatic trend in anɛ Sr(O)-ɛ Nd(O) diagram is the result of varying degrees of contamination of a "primitive arc-type" magma by the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4586675','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4586675"><span id="translatedtitle">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/2000Litho..53..117B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000Litho..53..117B"><span id="translatedtitle">Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> distribution in granulite-facies marbles: a witness of fluid rock interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boulvais, Philippe; Fourcade, Serge; Moine, Bernard; Gruau, Gérard; Cuney, Michel</p> <p>2000-08-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) distribution of marbles from Tranomaro (SE Madagascar) shows that the marbles have interacted with syn-metamorphic fluids during the Panafrican granulite-facies metamorphism. The Tranomaro area is characterized by an extensive development of pyroxenites (skarns) variably mineralized in uranothorianite and enriched in REE, Zr. Across a meter-scale marble-pyroxenite contact, the REE content increases from the most remote marble sample to the contact with the pyroxenite (La from 19.8 to 129 ppm). REE patterns in enriched marbles display a strong negative Eu anomaly similar to those of pyroxenites. This peculiar type of REE distribution results from fluid infiltration. On a regional scale, some marbles have similar REE characteristics (progressive development of Eu anomaly together with REE enrichment) showing that some of them have interacted with fluids. Infiltration was hardly recognizable using C and O isotopic signatures because large isotopic variations were introduced during the pre-granulitic history. Then, REE distribution in high-grade marble may be helpful in monitoring syn-metamorphic fluid flow. In the present case, it is a more reliable tracer of fluid infiltration than stable isotopic compositions.</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('http://adsabs.harvard.edu/abs/2013EGUGA..1513067L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1513067L"><span id="translatedtitle"><span class="hlt">Elements</span> of a new Global Water Strategy for the Group on <span class="hlt">Earth</span> Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lawford, Richard; Koike, Toshio; Ochiai, Osamu; Cripe, Douglas</p> <p>2013-04-01</p> <p>In order to address the need to review the scope and direction of GEO activities related to water and to provide guidance for the post-2015 GEO planning, the Integrated Global Water Cycle Observations (IGWCO) Community of Practice and the Committee on <span class="hlt">Earth</span> Observation Satellites (CEOS) are working together to develop a strategy for GEO water activities over the next decade. This presentation will review the <span class="hlt">elements</span> of the strategy which include topics as comprehensive as user needs and engagement, water cycle observational systems, assessment of water quality, data issues, interoperability and integration of water information systems and capacity building. Impediments in the flow of information and technological capabilities from the providers of new technologies, innovations and data products to the end users will be explored in terms of the nature of these impediments and how they can be overcome. To be successful in GEO's framework of volunteerism, the water strategy should build on activities that are on-going in related programmes at the international and national levels. In addition, implementation of the strategy will need to be supported through new initiatives and policies that promote greater integration. Suggestions for achieving these goals will be outlined at the end of the talk.</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 id="translatedtitle">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://www.osti.gov/pages/biblio/1265582-selective-extraction-rare-earth-elements-from-permanent-magnet-scraps-membrane-solvent-extraction','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1265582-selective-extraction-rare-earth-elements-from-permanent-magnet-scraps-membrane-solvent-extraction"><span id="translatedtitle">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 PAGESBeta</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 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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016NatSR...619961T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016NatSR...619961T&link_type=ABSTRACT"><span id="translatedtitle">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.ncbi.nlm.nih.gov/pubmed/27351211','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27351211"><span id="translatedtitle">Recovery of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> and Yttrium from Passive-Remediation Systems of Acid Mine Drainage.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ayora, Carlos; Macías, Francisco; Torres, Ester; Lozano, Alba; Carrero, Sergio; Nieto, José-Miguel; Pérez-López, Rafael; Fernández-Martínez, Alejandro; Castillo-Michel, Hiram</p> <p>2016-08-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> and yttrium (REY) are raw materials of increasing importance for modern technologies, and finding new sources has become a pressing need. Acid mine drainage (AMD) is commonly considered an environmental pollution issue. However, REY concentrations in AMD can be several orders of magnitude higher than in naturally occurring water bodies. With respect to shale standards, the REY distribution pattern in AMD is enriched in intermediate and valuable REY, such as Tb and Dy. The objective of the present work is to study the behavior of REY in AMD passive-remediation systems. Traditional AMD passive remediation systems are based on the reaction of AMD with calcite-based permeable substrates followed by decantation ponds. Experiments with two columns simulating AMD treatment demonstrate that schwertmannite does not accumulate REY, which, instead, are retained in the basaluminite residue. The same observation is made in two field-scale treatments from the Iberian Pyrite Belt (IPB, southwest Spain). On the basis of the amplitude of this process and on the extent of the IPB, our findings suggest that the proposed AMD remediation process can represent a modest but suitable REY source. In this sense, the IPB could function as a giant heap-leaching process of regional scale in which rain and oxygen act as natural driving forces with no energy investment. In addition to having environmental benefits of its treatment, AMD is expected to last for hundreds of years, and therefore, the total reserves are practically unlimited. PMID:27351211</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7302586','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7302586"><span id="translatedtitle">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('http://www.ncbi.nlm.nih.gov/pubmed/15285371','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15285371"><span id="translatedtitle">A method for predicting bioavailability of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soils to maize.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Wei-Sheng; Shan, Xiao-Quan; Wen, Bei; Zhang, Shu-Zhen</p> <p>2004-03-01</p> <p>A single-extraction procedure using low-molecular-weight organic acids (LMWOAs) as extractant and the first and second steps of a three-step extraction procedure recommended by the European Community Bureau of Reference (BCR; now European Community Standards, Measurement and Testing Programme, Brussels, Belgium) were performed to extract the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREEs) La, Ce, Pr, and Nd from wet rhizosphere soil. The extracted soil solutions were successively filtered through membranes with a pore size of less than 0.45 microm and a molecular weight cutoff of less than 1 kDa, which were termed colloidal and truly dissolved fractions, respectively. Apoplastically and symplastically bound LREEs in maize roots were experimentally distinguished by ultrasound-assisted desorption with 1 mM CaCl2 solution at 0 degrees C in ice-cooled water bath. When the LMWOAs extraction method was used, a good correlation was obtained between LREEs in soil colloidal and truly dissolved fractions and LREEs bound to apoplasm and symplasm of maize root. Both apoplastically and symplastically bound LREEs are the result of bioavailability. However, a poor correlation was obtained between LREEs in fractions water soluble, exchangeable and carbonate bound (B1) and Fe-Mn oxide bound (B2) of the BCR method and LREEs in apoplasm and symplasm and in intact roots. Hence, the LMWOAs extraction method is recommended for measuring the bioavailability of LREEs in soils. PMID:15285371</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984CoMP...88..328N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984CoMP...88..328N"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> mobility in vesicular lava during low-grade metamorphism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nyström, Jan Olov</p> <p>1984-12-01</p> <p>A geochemical comparison of basaltic relicts and spilitic domains from two burial metamorphosed flows in central Chile, of similar original composition and rich and poor in amygdules, respectively, demonstrates a relationship between initial vesicularity and rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) mobility. During spilitization the REE were partly leached from permeable parts of the flows and precipitated in voids, now amygdules and veinlets. The REE (excluding Eu) moved coherently in the highly amygdaloidal flow: spilitic domains and amygdules inherited the basaltic REE pattern. Besides being characterized by a positive Eu anomaly, epidotes separated from amygdules have a REE distribution which mimics that of the basalt; the absolute contents range widely, suggesting local and/or temporal REE variations in the metamorphic fluids. Pumpellyite differs by being strongly enriched in heavy REE. Similar ratios of Th, Hf and Ta in samples as contrasting as relict basalt and a geode are consistent with coherent leaching. Coherent mobility, when established for a rock system, can be used to elucidate, for example, whether minerals in cross-cutting veins were formed by local redistribution or from introduced material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26819083','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26819083"><span id="translatedtitle">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=pubmed">PubMed</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('http://ntrs.nasa.gov/search.jsp?R=19770064910&hterms=Rare+earth+metals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528%2528Rare%2Bearth%2529%2Bmetals%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19770064910&hterms=Rare+earth+metals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528%2528Rare%2Bearth%2529%2Bmetals%2529"><span id="translatedtitle">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('http://www.ncbi.nlm.nih.gov/pubmed/27190151','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27190151"><span id="translatedtitle">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.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gu, Wenyu; Farhan Ul Haque, Muhammad; DiSpirito, Alan A; Semrau, Jeremy D</p> <p>2016-07-01</p> <p>It is well known that Methylosinus trichosporium OB3b has two forms of methane monooxygenase (MMO) responsible for the initial conversion of methane to methanol, a cytoplasmic (soluble) methane monooxygenase and a membrane-associated (particulate) methane monooxygenase, 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-type MeDH (Mxa-MeDH) and Xox-type MeDH (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> (REE), cerium. Here, we extend these studies and show that lanthanum, praseodymium, neodymium and samarium also regulate expression of alternative forms of MeDH. The effect of these REEs 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. 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. PMID:27190151</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26378553','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26378553"><span id="translatedtitle">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=pubmed">PubMed</a></p> <p>Butnariu, Monica; Negrea, Petru; Lupa, Lavinia; Ciopec, Mihaela; Negrea, Adina; Pentea, Marius; Sarac, Ionut; Samfira, Ionel</p> <p>2015-09-01</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://pubs.er.usgs.gov/publication/70014731','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014731"><span id="translatedtitle">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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4730208','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4730208"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2013PhRvL.111x2502G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvL.111x2502G"><span id="translatedtitle">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="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goriely, S.; Sida, J.-L.; Lemaître, J.-F.; Panebianco, S.; Dubray, N.; Hilaire, S.; Bauswein, A.; Janka, H.-T.</p> <p>2013-12-01</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" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25894494','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25894494"><span id="translatedtitle">Red Phosphorus: An <span class="hlt">Earth</span>-Abundant <span class="hlt">Elemental</span> Photocatalyst for "Green" Bacterial Inactivation under Visible Light.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xia, Dehua; Shen, Zhurui; Huang, Guocheng; Wang, Wanjun; Yu, Jimmy C; Wong, Po Keung</p> <p>2015-05-19</p> <p><span class="hlt">Earth</span>-abundant red phosphorus was found to exhibit remarkable efficiency to inactivate Escherichia coli K-12 under the full spectrum of visible light and even sunlight. The reactive oxygen species (•OH, •O2(-), H2O2), which were measured and identified to derive mainly from photogenerated electrons in the conduction band using fluorescent probes and scavengers, collectively contributed to the good performance of red phosphorus. Especially, the inactivated-membrane function enzymes were found to be associated with great loss of respiratory and ATP synthesis activity, the kinetics of which paralleled cell death and occurred much earlier than those of cytoplasmic proteins and chromosomal DNA. This indicated that the cell membrane was a vital first target for reactive oxygen species oxidation. The increased permeability of the cell membrane consequently accelerated intracellular protein carboxylation and DNA degradation to cause definite bacterial death. Microscopic analyses further confirmed the cell destruction process starting with the cell envelope and extending to the intracellular components. The red phosphorus still maintained good performance even after recycling through five reaction cycles. This work offers new insight into the exploration and use of an <span class="hlt">elemental</span> photocatalyst for "green" environmental applications. PMID:25894494</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 id="translatedtitle">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('http://www.ncbi.nlm.nih.gov/pubmed/25920439','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25920439"><span id="translatedtitle">Determination of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Hypersaline Solutions Using Low-Volume, Liquid-Liquid Extraction.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Noack, Clinton W; Dzombak, David A; Karamalidis, Athanasios K</p> <p>2015-08-18</p> <p>Complex, hypersaline brines-including those coproduced with oil and gas, rejected from desalination technologies, or used as working fluids for geothermal electricity generation-could contain critical materials such as the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in valuable concentrations. Accurate quantitation of these analytes in complex, aqueous matrices is necessary for evaluation and implementation of systems aimed at recovering those critical materials. However, most analytical methods for measuring trace metals have not been validated for highly saline and/or chemically complex brines. Here we modified and optimized previously published liquid-liquid extraction (LLE) techniques using bis(2-ethylhexyl) phosphate as the extractant in a heptane diluent, and studied its efficacy for REE recovery as a function of three primary variables: background salinity (as NaCl), concentration of a competing species (here Fe), and concentration of dissolved organic carbon (DOC). Results showed that the modified LLE was robust to a range of salinity, Fe, and DOC concentrations studied as well as constant, elevated Ba concentrations. With proper characterization of the natural samples of interest, this method could be deployed for accurate analysis of REE in small volumes of hyper-saline and chemically complex brines. PMID:25920439</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 id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/26107531','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26107531"><span id="translatedtitle">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.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. PMID:26107531</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('http://adsabs.harvard.edu/abs/2007JMMM..312..310J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JMMM..312..310J"><span id="translatedtitle">Microwave absorbing properties of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> substituted W-type barium ferrite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jing, Wang; Hong, Zhang; Shuxin, Bai; Ke, Chen; Changrui, Zhang</p> <p>2007-05-01</p> <p>W-type barium ferrites Ba(MnZn) 0.3Co 1.4R 0.01Fe 15.99O 27 with R=Dy, Nd and Pr were prepared by chemical coprecipitation method. Effects of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (RE) substitution on microstructural and electromagnetic properties were analyzed. The results show that a small amount of RE 3+ ions can replace Fe 3+ ions and adjust hyperfine parameters. An obvious increase in natural resonance frequency and high frequency relaxation, and a sharp decrease for complex permittivity have been observed. Furthermore, the matching thickness and the reflection loss (RL) of one-layer ferrite absorber were calculated. It reveals that thin and broad-band can be obtained by RE-substitution. But only when the magnetic moment of RE 3+ is higher than that of Fe 3+, can substitution be effective for higher RL. Dy-substituted ferrite composite has excellent microwave absorption properties. The frequency (with respect to -10 dB RL) begins from 9.9 GHz, and the bandwidth reaches far more than 8.16 GHz. The peak value is -51.92 dB at a matching thickness of 2.1 mm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24972173','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24972173"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> distributions and fractionation in plankton from the northwestern Mediterranean Sea.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Strady, Emilie; Kim, Intae; Radakovitch, Olivier; Kim, Guebuem</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations were measured for the first time in plankton from the northwestern Mediterranean Sea. The REE concentrations in phytoplankton (60-200 μm) were 5-15 times higher than those in four size fractions of zooplankton: 200-500 μm, 500-1000 μm, 1000-2000 μm and >2000 μm. The concentrations within these zooplankton fractions exhibited the same ranges with some variation attributed to differences in zooplankton taxonomy. The REE concentrations in plankton were poorly related to the reported REE concentrations of seawater, but they correlated well with the calculated REE(3+), concentrations especially with regard to middle REE (MREEs) and heavy REEs (HREEs). Plankton and seawater revealed different PAAS-normalised REE distributions, with the greatest differences observed in the light REEs. Interestingly, a comparison of PAAS-normalized sediment particles from the study of Fowler et al. (1992) showed concentrations of the same order of magnitude and a similar REE distribution without MREE enrichment. Based on this comparison, we propose a conceptual model that emphasizes the importance of biological scavenging of REEs (especially LREEs) in surface waters. PMID:24972173</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27081794','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27081794"><span id="translatedtitle">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="http://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. PMID:27081794</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24483647','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24483647"><span id="translatedtitle">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="http://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. PMID:24483647</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750051000&hterms=Yttrium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DYttrium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750051000&hterms=Yttrium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DYttrium"><span id="translatedtitle">Fractionation in the solar nebula - Condensation of yttrium and the 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>Boynton, W. V.</p> <p>1975-01-01</p> <p>The condensation of Y and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) from the solar nebula may be controlled by thermodynamic equilibrium between gas and condensed solids. Highly fractionated REE patterns may result if condensates are removed from the gas before condensation is complete. It is found that the fractionation is not a smooth function of REE ionic radius but varies in an extremely irregular pattern. Both Yb and Eu are predicted to be extremely depleted in the early condensate without the requirement of condensation in the divalent state. The model is discussed with respect to a highly fractionated pattern observed by Tanaka and Masuda (1973), in a pink Ca-Al-rich inclusion from the Allende meteorite and can account for the abundances of each REE determined. According to the model this inclusion represents a condensate from a previously fractionated gas rather than from a gas of solar composition. Before the condensation of this inclusion, an earlier condensate was formed and was removed from equilibrium with the gas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMMR23B2653M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMMR23B2653M"><span id="translatedtitle">Light <span class="hlt">element</span> partitioning between silicate and metallic melts: Insights into the formation and composition of <span class="hlt">Earth</span>'s core</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Myhill, R.; Rubie, D. C.; Frost, D. J.</p> <p>2015-12-01</p> <p>The mass deficit of the <span class="hlt">Earth</span>'s core, and the increasing solubility of light <span class="hlt">elements</span> into metallic iron with increasing pressure demonstrate that the <span class="hlt">Earth</span>'s core must contain several weight percent of light <span class="hlt">elements</span> such as Si, O, C and S. These light <span class="hlt">elements</span> place important constraints on the depth of the primordial magma ocean(s), the chemical potentials of many of these <span class="hlt">elements</span> in coexisting phases during differentiation, the temperature of the inner core boundary, and the composition of the bulk <span class="hlt">Earth</span>. The P-wave velocity, <span class="hlt">Earth</span>'s mass deficit, and depth of the inner core boundary place two important constraints on the chemical composition of the core, but there are multiple trade-offs which cannot be resolved using seismology alone. In this study, we use a large experimental partitioning dataset to build activity-composition models for light <span class="hlt">elements</span> in metallic melts in equilibrium with oxide and silicate phases (both solid and liquid). We avoid the use of epsilon models, which commonly fail at solute concentrations above a few weight percent. Instead we employ a modified subregular solution model, using intermediate species to calculate excess free energies of mixing. Flexible models like these are required to fit the experimental data which spans 0 - 100 GPa and 1500 - 5500 K. Several heuristics are used to reduce the number of free parameters where they are not independently constrained. We use our models to investigate the conditions of core formation and the chemical composition of the <span class="hlt">Earth</span>'s core using the approach of Rubie et al. (2015; Icarus v.248; pp 89-108).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GeCoA..66.1323D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GeCoA..66.1323D"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the water column of Lake Vanda, McMurdo Dry Valleys, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Carlo, Eric Heinen; Green, William J.</p> <p>2002-04-01</p> <p>We present data on the composition of water from Lake Vanda, Antarctica. Vanda and other lakes in the McMurdo Dry Valleys of Antarctica are characterized by closed basins, permanent ice covers, and deep saline waters. The meromictic lakes provide model systems for the study of trace metal cycling owing to their pristine nature and the relative simplicity of their biogeochemical systems. Lake Vanda, in the Wright Valley, is supplied by a single input, the Onyx River, and has no output. Water input to the lake is balanced by sublimation of the nearly permanent ice cap that is broken only near the shoreline during the austral summer. The water column is characterized by an inverse thermal stratification of anoxic warm hypersaline water underlying cold oxic freshwater. Water collected under trace-<span class="hlt">element</span> clean conditions was analyzed for its dissolved and total rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations by inductively coupled plasma mass spectrometry. Depth profiles are characterized by low dissolved REE concentrations (La, Ce, <15 pM) in surface waters that increase slightly (La, 70 pM; Ce, 20 pM) with increasing depth to ˜55 m, the limit of the fresh oxic waters. Below this depth, a sharp increase in the concentrations of strictly trivalent REE (e.g., La, 5 nM) is observed, and a submaximum in redox sensitive Ce (2.6 nM) is found at 60- to 62-m depth. At a slightly deeper depth, a sharper Ce maximum is observed with concentrations exceeding 11 nM at a 67-m depth, immediately above the anoxic zone. The aquatic concentrations of REE reported here are ˜50-fold higher than previously reported for marine oxic/anoxic boundaries and are, to our knowledge, the highest ever observed at natural oxic/anoxic interfaces. REE maxima occur within stable and warm saline waters. All REE concentrations decrease sharply in the sulfidic bottom waters. The redox-cline in Lake Vanda is dominated by diffusional processes and vertical transport of dissolved species driven by concentration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUSM...V22A06H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUSM...V22A06H"><span id="translatedtitle">Chemical Weathering of Black Shales and Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Composition of Surface Waters and Groundwater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hannigan, R. E.; Johannesson, K. H.</p> <p>2001-05-01</p> <p>Weathering processes dominate the dissolved and suspended loads of most of the world's major rivers. Among sedimentary rocks, black shales are particularly sensitive to chemical weathering. Therefore, shale systems are useful for investigating the partitioning of chemical <span class="hlt">elements</span> during chemical weathering. Recent studies, such as those by Peucker-Ehrenbrink, Ravizza and others, link chemical weathering of black shales to changes in marine isotopic composition. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) have a unique chemistry and are ideal for such tracer studies. We explored the effect of modern chemical weathering of black shales on the hydrochemistry of surface and groundwaters in the Mohawk Valley of New York State. This region provides an ideal site for the investigation of trace <span class="hlt">element</span> remobilization during the chemical weathering of black shales. In this region, surface and groundwaters, in intimate contact with black shales and have high dissolved metal concentrations presumably due to water-rock interactions. The extent to which the dissolved REE composition of the surface and ground waters retains the rock signature is, in someway related to the length of time that the water remains in contact with the rock. We compared the REE compositions of surface and groundwaters in areas draining black shale to those of waters draining regions of dolostone-limestone to explore the extent of metal release due to chemical weathering. Shale normalized REE patterns for stream waters exhibit slight heavy REE enrichments and, at some locations, LREE depletion. REE patterns of the waters normalized to their respective sediments show some LREE depletion. However, waters associated with the Little Falls dolomite show fractionation predominantly enriched in the heavy REEs. Differences between the black shale sites, recorded as light REE depletion and/or middle REE enrichment, may be related to the discharge of the streams and the total dissolved solids. The dissolved REE chemistry of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1594..388W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1594..388W"><span id="translatedtitle">β-decay of neutron-rich Zâ¼60 nuclei and the origin 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>Wu, J.; Nishimura, S.; Lorusso, G.; Xu, Z. Y.; Baba, H.; Browne, F.; Daido, R.; Doornenbal, P.; Fang, Y. F.; Ideguchi, E.; Isobe, T.; Li, Z.; Patel, Z.; Rice, S.; Simpson, G.; Sinclair, L.; Söderström, P. A.; Sumikama, T.; Watanabe, H.; Yagi, A.; Yokoyama, R.; Aoi, N.; Garrote, F. L. Bello; Benzoni, G.; Gey, G.; Gottardo, A.; Nishibata, H.; Odahara, A.; Sakurai, H.; Tanaka, M.; Taprogge, J.; Yamamoto, T.; Eurica Collaboration</p> <p>2014-05-01</p> <p>A large fraction of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> observed in the solar system is produced in the astrophysical rapid neutron capture process (r-process). However, current stellar models cannot completely explain the relative abundance of these <span class="hlt">elements</span> partially because of nuclear physics uncertainties. To address this problem, a β-decay spectroscopy experiment was performed at RI Beam Factory (RIBF) at RIKEN, aimed at studying a wide range of very neutron-rich nuclei with Z˜60 that are progenitors of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> with mass number A˜460. The experiment provides a test of nuclear models as well as experimental inputs for r-process calculations. This contribution presents the experimental setup and some preliminary results of the experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22280491','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22280491"><span id="translatedtitle">β-decay of neutron-rich Z∼60 nuclei and the origin of 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>Wu, J.; Nishimura, S.; Lorusso, G.; Baba, H.; Doornenbal, P.; Isobe, T.; Söderström, P. A.; Sakurai, H.; Xu, Z. Y.; Browne, F.; Daido, R.; Fang, Y. F.; Yagi, A.; Nishibata, H.; Odahara, A.; Yamamoto, T.; Ideguchi, E.; Aoi, N.; Tanaka, M.; Collaboration: EURICA Collaboration; and others</p> <p>2014-05-02</p> <p>A large fraction of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> observed in the solar system is produced in the astrophysical rapid neutron capture process (r-process). However, current stellar models cannot completely explain the relative abundance of these <span class="hlt">elements</span> partially because of nuclear physics uncertainties. To address this problem, a β-decay spectroscopy experiment was performed at RI Beam Factory (RIBF) at RIKEN, aimed at studying a wide range of very neutron-rich nuclei with Z∼60 that are progenitors of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> with mass number A∼460. The experiment provides a test of nuclear models as well as experimental inputs for r-process calculations. This contribution presents the experimental setup and some preliminary results of the experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712022W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712022W"><span id="translatedtitle">Assessment of Bioavailable Concentrations of Germanium and Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in the Rhizosphere of White Lupin (Lupinus albus L.)</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; Fischer, Ronny; Moschner, Christin; Székely, Balázs</p> <p>2015-04-01</p> <p>Concentrations of Germanium (Ge) and Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in soils are estimated at 1.5 mg kg -1 (Ge), 25 mg kg -1 (La) and 20 mg kg -1 (Nd), which are only roughly smaller than concentrations of Pb and Zn. Germanium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> are thus not rare but widely dispersed in soils and therefore up to date, only a few minable deposits are available. An environmental friendly and cost-effective way for Ge and rare <span class="hlt">earth</span> <span class="hlt">element</span> production could be phytomining. However, the most challenging part of a phytomining of these <span class="hlt">elements</span> is to increase bioavailable concentrations of the <span class="hlt">elements</span> in soils. Recent studies show, that mixed cultures with white lupine or other species with a high potential to mobilize trace metals in their rhizosphere due to an acidification of the soil and release of organic acids in the root zone could be a promising tool for phytomining. Complexation of Ge and rare <span class="hlt">earth</span> <span class="hlt">elements</span> by organic acids might play a key role in controlling bioavailability to plants as re-adsorption on soil particles and precipitation is prevented and thus, concentrations in the root zone of white lupine increase. This may also allow the complexes to diffuse along a concentration gradient to the roots of mixed culture growing species leading to enhanced plant uptake. However, to optimize mixed cultures it would be interesting to know to which extend mobilization of trace metals is dependent from chemical speciation of <span class="hlt">elements</span> in soil due to the interspecific interaction of roots. A method for the identification of complexes of germanium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> with organic acids, predominantly citric acid in the rhizosphere of white lupine was developed and successfully tested. The method is based on coupling of liquid chromatography with ICP-MS using a zic-philic column (SeQuant). As a preliminary result, we were able to show that complexes of germanium with citric acid exist in the rhizosphere of white lupin, what may contribute to the bioavailability of this</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25269316','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25269316"><span id="translatedtitle">[Indirect determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Chinese herbal medicines by hydride generation-atomic fluorescence spectrometry].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zeng, Chao; Lu, Jian-Ping; Xue, Min-Hua; Tan, Fang-Wei; Wu, Xiao-Yan</p> <p>2014-07-01</p> <p>Based on their similarity in chemical properties, rare <span class="hlt">earth</span> <span class="hlt">elements</span> were able to form stable coordinated compounds with arsenazo III which were extractable into butanol in the presence of diphenylguanidine. The butanol was removed under reduced pressure distillation; the residue was dissolved with diluted hydrochloric acid. As was released with the assistance of KMnO4 and determined by hydrogen generation-atomic fluorescence spectrometry in terms of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. When cesium sulfate worked as standard solution, extraction conditions, KMnO4 amount, distillation temperature, arsenazo III amount, interfering ions, etc were optimized. The accuracy and precision of the method were validated using national standard certified materials, showing a good agreement. Under optimum condition, the linear relationship located in 0.2-25 microg x mL(-1) and detection limit was 0.44 microg x mL(-1). After the herbal samples were digested with nitric acid and hydrogen peroxide, the rare <span class="hlt">earth</span> <span class="hlt">elements</span> were determined by this method, showing satisfactory results with relative standard deviation of 1.3%-2.5%, and recoveries of 94.4%-106.0%. The method showed the merits of convenience and rapidness, simple instrumentation and high accuracy. With the rare <span class="hlt">earths</span> enriched into organic phase, the separation of analytes from matrix was accomplished, which eliminated the interference. With the residue dissolved by diluted hydrochloric acid after the solvent was removed, aqueous sample introduction eliminated the impact of organic phase on the tubing connected to pneumatic pump. PMID:25269316</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012E%26PSL.335..121P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012E%26PSL.335..121P"><span id="translatedtitle">Environmental changes across the Triassic-Jurassic boundary and coeval volcanism inferred from <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> and mineralogy in the Kendlbachgraben section (Northern Calcareous Alps, Austria)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pálfy, József; Zajzon, Norbert</p> <p>2012-06-01</p> <p>The end-Triassic extinction (ETE), one of the five largest Phanerozoic mass extinctions, is associated with rapid and severe environmental change, but existing data permit alternative models of causation. Volcanism in the Central Atlantic Magmatic Province (CAMP) has been proposed as the main trigger, but direct evidence for this linkage is scarce. To help constrain scenarios for the ETE and other Triassic-Jurassic boundary (TJB) events, we obtained a temporally highly resolved, multidisciplinary dataset from the Kendlbachgraben section in the Northern Calcareous Alps in Austria. The section belongs to the same paleogeographic unit (Eiberg Basin) and share similar stratigraphy with the recently selected base Jurassic Global Stratotype Section and Point at Kuhjoch. Micromineralogic study of the topmost bed of the Rhaetian Kössen Formation revealed pseudomorphs of altered, euhedral pyroxene and amphibole crystals. Their well-faceted morphology is consistent with their origin from distal mafic volcanic ash fallout. Spherical grains were also observed in the same bed, likely representing clay-altered volcanic glass. Clay minerals of this bed include low- to medium-charged smectite and Mg-vermiculite, both typical alteration products of mafic rocks. The same bed yielded a rare <span class="hlt">earth</span> <span class="hlt">element</span> pattern that differs from all other levels in an enrichment of heavy REEs, hinting at some minor contribution from mafic magmatic material. These features from a layer that was deposited very near to the TJB are interpreted as direct evidence of CAMP volcanism, coeval or immediately preceding the ETE and the initial negative carbon isotope anomaly. The kaolinite-dominated clay mineral spectrum of the overlying boundary mudstone records intensive weathering under hot and humid greenhouse conditions. Redox-sensitive minor and trace <span class="hlt">elements</span> do not support the development of widespread anoxia in the studied section. Although pyrite is common in several layers, framboid size indicates</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011541','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011541"><span id="translatedtitle">Genetic implications of minor-<span class="hlt">element</span> and Sr-isotope <span class="hlt">geochemistry</span> of alkaline rock complexes in the Wet Mountains area, Fremont and Custer counties, Colorado</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Armbrustmacher, T.J.; Hedge, C.E.</p> <p>1982-01-01</p> <p>Concentrations of Rb, Sr, and REE (rare <span class="hlt">earth</span> <span class="hlt">elements</span>), and Sr-isotopic ratios in rocks of the Cambrian alkaline complexes in the Wet Mountains area, Colorado, show that rocks formed as end-products of a variety of magmas generated from different source materials. The complexes generally contain a bimodal suite of cumulus mafic-ultramafic rocks and younger leucocratic rocks that include nepheline syenite and hornblende-biotite syenite in the McClure Mountain Complex, nepheline syenite pegmatite in the Gem Park Complex, and quartz syenite in the complex at Democrat Creek. The nepheline syenite and hornblende-biotite syenite at McClure Mountain (535??5m.y.) are older than the syenitic rocks at Democrat Creek (511??8m.y.). REE concentrations indicate that the nepheline syenite at McClure Mountain cannot be derived from the hornblende-biotite syenite, which it intrudes, or from the associated mafic-ultramafic rocks. REE also indicate that mafic-ultramafic rocks at McClure Mountain have a source distinct from that of the mafic-ultramafic rocks at Democrat Creek. In the McClure Mountain Complex, initial87Sr/86Sr ratios for mafic-ultramafic rocks (0.7046??0.0002) are similar to those of hornblende-biotite syenite (0.7045??0.0002), suggesting a similar magmatic source, whereas ratios for carbonatites (0.7038??0.0002) are similar to those of nepheline syenite (0.7038??0.0002). At Democrat Creek, initial ratios of syenitic rocks (0.7032??0.0002) and mafic-ultramafic rocks (0.7028??0.0002) are different from those of corresponding rocks at McClure Mountain. ?? 1982 Springer-Verlag.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7597Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7597Z"><span id="translatedtitle">Rare <span class="hlt">earth</span> and trace <span class="hlt">elements</span> of fossil vertebrate bioapatite as palaeoenvironmental and sedimentological proxies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Žigaitė, Živilė; Fadel, Alexandre; Pérez-Huerta, Alberto; Jeffries, Teresa</p> <p>2015-04-01</p> <p>Rare <span class="hlt">earth</span> (REE) and trace <span class="hlt">element</span> compositions of fossil vertebrate dental microremains have been studied in Silurian and Devonian vertebrate dental scales and spines in-situ, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Samples were selected from the well-known Silurian bone beds of Vesiku and Ohesaare in Saaremaa island of Estonia, and a number of Lower Devonian localities from Spitsbergen (Svalbard), Andrée Land group. Biomineral preservation was assessed using spot semi-quantitative <span class="hlt">elemental</span> chemistry (SEM-EDS) and electron back-scatter difractometry (EBSD) for cristallinity imaging. The obtained PAAS shale-normalised REE concentrations were evaluated using basic geochemical calculations and quantifications. The REE patterns from the Lower Devonian vertebrate apatite from Andrée Land, Spitsbergen (Wood Bay and Grey Hœk formations) did not show any recognisable taxon-specific behavior, but had rather well expressed differences of REE compositions related to biomineral structure and sedimentary settings, suggesting REE instead to reflect burial environments and sedimentological history. The Eu anomaly recorded in two of the studied localities but not in the other indicate different taphonomic conditions and palaeoenvironment, while La/Sm, La/Yb ratios sugeest considerable influence of terrestrial freshwater during the early diagenesis. The La/Yb and La/Sm plots also agree with the average REE concentrations, reflecting domination of the adsoption over substitution as principal REE uptake mechanism in the fossils which had significantly lower overall REE concentrations, and vice versa. Vesiku (Homerian, Wenlock) microremains yielded very uniform REE patterns with slightly lower overall REE concentrations in enameloid than in dentine, with strong enrichment in middle REE and depletion in heavy REE. Negative Europium (Eu) anomaly was pronounced in all the profiles, but Cerium (Ce) anomalies were not detected suggesting possible</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7182962','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7182962"><span id="translatedtitle">Ocean particle chemistry: The fractionation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> between suspended particles and seawater</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sholkovitz, E.R. ); Landing, W.M.; Lewis, B.L. )</p> <p>1994-03-01</p> <p>Sargasso Sea suspended particles were sequentially digested with three chemical treatments (acetic acid, mild HCl/HNO[sub 3], and HF/HNO[sub 3]/HCl in a bomb). The latter two treatments dissolve detrital minerals, while the acetic acid removes surface coatings (organic matter and Mn oxides). The rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) composition of the surface coatings, in marked contrast to the crust-like REE composition of the two detrital phases, is extensively fractionated with respect to both filtered seawater and the crust. Surface coatings are responsible for the removal and fractionation of REEs from seawater and, as such, play a key role in the marine geochemical cycles of trace <span class="hlt">elements</span>. Relative to seawater, the surface coatings are systematically enriched tenfold across the trivalent REEs from Lu to La and develop large positive Ce-anomalies. The Ce-anomalies of the coatings switch from being negative (seawater-like) in the upper 100 m to being strongly positive at greater depths. The ingrowth of Ce and LREEs on particle surfaces reflects the in situ oxidation of dissolved Ce(III) to particulate Ce(IV), and the preferential removal of LREE(III)s over HREE(III)s. REEs(III) fractionation of this type is consistent with particle/solution models. Both processes appear to be related to the in situ formation of Mn oxide particles from the oxidation of dissolved Mn(II) in the upper 200 m of the water column. Preferential removal of LREEs in the upper waters is countered by their preferential release at depth due to remineralization of surface coatings on particles. A new method is explored for estimating the residence time of suspended particles by combining Ce concentration data of dissolved and surface-bound phases with the Ce(III) oxidation rate measurements of MOFFETT (1990). A Ce-based residence time of thirteen days is similar in magnitude to the value calculated from U-[sup 234]Th disequilibria in the Sargasso Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815722F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815722F"><span id="translatedtitle">LiF - a spectroscopic method for rare <span class="hlt">earth</span> <span class="hlt">elements</span> identification</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fuchs, Margret; Gloaguen, Richard; Beyer, Jan; Jacob, Sandra; Heitmann, Johannes</p> <p>2016-04-01</p> <p>Laser-induced fluorescence (LiF) has a great potential for the exploration and identification of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in natural environments. This spectroscopic technique can provide an efficient way to secure resource availability, while the economic and ecological costs are reduced. No time-consuming sample preparation and analysis is needed prior to decisions along the raw material processing chain. Such non-destructive approaches allow for a fast access to analytical results and hence, are the basis for an immediate adjustment of processing steps. The method uses the material-specific luminescence emissions that are induced by laser-stimulation of a certain wavelength. The distinct emission lines of REE make them well suited for the development of a LiF-based exploration technique. However, typical REE emission peaks known from the free <span class="hlt">elements</span> may shift or be masked in natural materials due to their position in the crystal lattice, varying compositions of minerals or other natural conditions such as water content. The natural variability therefore, demands for comprehensive investigations of REE and their spectral characteristics in minerals. To identify those spectral information that are robust and unequivocal, we analyse spectra of REE standards measured in different matrix minerals including phosphates and fluorides. We use variable laser wavelengths from UV (325 nm) to green (532 nm) and a detection range from 340 nm to 1080 nm. Results show spectral characteristics that sort REE in three groups due to: no distinct emission lines, absorption features, distinct luminescence emission lines. Measured in different matrix minerals, we determine shifts for some of the spectral features and some disappear or decline in intensity. Changing the wavelength of the laser allows for a more selective stimulation of REE emissions, especially wavelengths longer than UV can reduce the unspecific emission of all luminescent components of a sample and thus enhance</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGC51F1167S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGC51F1167S"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in pore waters from Cabo Friós western boundary upwelling system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smoak, J. M.; Silva-Filho, E. V.; Rousseau, T.; Albuquerque, A. L.; Caldeira, P. P.; Moreira, M.</p> <p>2015-12-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are a group of reactive trace <span class="hlt">elements</span> in aqueous media, they have a coherent chemical behavior with however a subtle and gradual shift in physicochemical properties allowing their use as tracers of sources and processes. Uncertainties on their oceanic inputs and outputs still remains [Arsouze et al., 2009; Siddall et al., 2008; Tachikawa et al., 2003]. The water-sediment interface were early on identified as a relevant REE source due to the high distribution coefficient between sediments and pore waters [Elderfield and Sholkovitz, 1987] and substantially higher concentration then the water column [Abbott et al., 2015; Haley et al., 2004; Sholkovitz et al., 1989; Soyol-Erdene and Huh, 2013]. Here we present a cross shelf transect of 4 short pore waters REE profiles on a 680 km2 mud bank located in the region of Cabo Frio, Brazil. This study reveals similar trends at the four sites: a REE production zone reflected by a maximum in concentration at the top of the sediment evolving with depth toward a REE consumption zone reflected by a minimum in REE concentrations. PAAS normalized patterns shows 1) a progressive depletion in LREE with depth with HREE/LREE ratios comprised between 1.1 and 1.6 in the 2 first centimeters evolving gradually to ratios comprised between 2.8 and 4.7 above 7 cm 2) A sharp gradient in negative Ce anomaly with Ce/Ce* values reaching 0.3. With maximum Nd concentrations comprised between 780 and 1200 pmol.kg and considering that seawater Nd concentrations of Brazilian shelf bottom waters are comprised between 24 and 50 pmol.Kg-1 we apply the Fick´s First Law of diffusion and estimate that 340 +/- 90 nmol. m-2 Y-1 of Nd is released in the Cabo frio´s mudbank. This flux is in the same order of magnitude of recent estimates by [Abbott et al., 2015] in the slope of Oregon´s margin. Unraveling processes responsible for the REE production zone will help to refine the global REE fluxes estimates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090020501','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090020501"><span id="translatedtitle">Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Measurements of Melilite and Fassaite in Allende Cai by Nanosims</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ito, M.; Messenger, Scott</p> <p>2009-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are concentrated in CAIs by approx. 20 times the chondritic average [e.g., 1]. The REEs in CAIs are important to understand processes of CAI formation including the role of volatilization, condensation, and fractional crystallization [1,2]. REE measurements are a well established application of ion microprobes [e.g., 3]. However the spatial resolution of REE measurements by ion microprobe (approx.20 m) is not adequate to resolve heterogeneous distributions of REEs among/within minerals. We have developed methods for measuring REE with the NanoSIMS 50L at smaller spatial scales. Here we present our initial measurements of REEs in melilite and fassaite in an Allende Type-A CAI with the JSC NanoSIMS 50L. We found that the key parameters for accurate REE abundance measurements differ between the NanoSIMS and conventional SIMS, in particular the oxide-to-<span class="hlt">element</span> ratios, the relative sensitivity factors, the energy distributions, and requisite energy offset. Our REE abundance measurements of the 100 ppm REE diopside glass standards yielded good reproducibility and accuracy, 0.5-2.5 % and 5-25 %, respectively. We determined abundances and spatial distributions of REEs in core and rim within single crystals of fassaite, and adjacent melilite with 5-10 m spatial resolution. The REE abundances in fassaite core and rim are 20-100 times CI abundance but show a large negative Eu anomaly, exhibiting a well-defined Group III pattern. This is consistent with previous work [4]. On the other hand, adjacent melilite shows modified Group II pattern with no strong depletions of Eu and Yb, and no Tm positive anomaly. REE abundances (2-10 x CI) were lower than that of fassaite. These patterns suggest that fassaite crystallized first followed by a crystallization of melilite from the residual melt. In future work, we will carry out a correlated study of O and Mg isotopes and REEs of the CAI in order to better understand the nature and timescales of its</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GGG....16.2679Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GGG....16.2679Z"><span id="translatedtitle">Factors affecting the rare <span class="hlt">earth</span> <span class="hlt">element</span> compositions in massive sulfides from deep-sea hydrothermal systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zeng, Zhigang; Ma, Yao; Yin, Xuebo; Selby, David; Kong, Fancui; Chen, Shuai</p> <p>2015-09-01</p> <p>To reconstruct the evolution of ore-forming fluids and determine the physicochemical conditions of deposition associated with seafloor massive sulfides, we must better understand the sources of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), the factors that affect the REE abundance in the sulfides, and the REE flux from hydrothermal fluids to the sulfides. Here we examine the REE profiles of 46 massive sulfide samples collected from seven seafloor hydrothermal systems. These profiles feature variable total REE concentrations (37.2-4092 ppb) and REE distribution patterns (LaCN/LuCN ratios = 2.00-73.8; (Eu/Eu*)CN ratios = 0.34-7.60). The majority of the REE distribution patterns in the sulfides are similar to those of vent fluids, with the sulfides also exhibiting light REE enrichment. We demonstrate that the variable REE concentrations, Eu anomalies, and fractionation between light REEs and heavy REEs in the sulfides exhibit a relationship with the REE properties of the sulfide-forming fluids and the massive sulfide chemistry. Based on the sulfide REE data, we estimate that modern seafloor sulfide deposits contain approximately 280 t of REEs. According to the flux of hydrothermal fluids at mid-ocean ridges (MORs) and an average REE concentration of 3 ng/g in these fluids, hydrothermal vents at MORs alone transport more REEs (>360 t) to the oceans over the course of just 2 years than the total quantity of REEs in seafloor sulfides. The excess REEs (i.e., the quantity not captured by massive sulfides) may be transported away from the systems and become bound in sulfate deposits and metalliferous sediments.</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('http://adsabs.harvard.edu/abs/2013GeCoA.103..161H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.103..161H"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> systematics of fossil bone revealed by LA-ICPMS analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herwartz, Daniel; Tütken, Thomas; Jochum, Klaus Peter; Sander, P. Martin</p> <p>2013-02-01</p> <p>Intra-bone rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) fractionation trends were studied by LA-ICPMS analysis to put constraints on (1) the mechanisms controlling REE fractionation within fossil bones; (2) the relative timing of REE uptake in various parts of fossil bone and (3) the origin of REE in fossil bones. We have evaluated REE bone profiles across 54 fossil bones from a broad range of well-characterised taphonomic settings ranging in age from Triassic to early Medieval. REE patterns and concentration gradients are highly variable and intra-bone fractionation trends in (La/Yb)N vs. (La/Sm)N space of few specimens cover almost the entire range previously observed for bulk samples. Intra-bone variability of Ce anomalies, as well as variable Y/Ho and (La/La∗)N is also observed. Sometimes, diagenetic fluids with fractionated, HREE enriched compositions have entered the bone from the marrow cavity, producing secondary REE uptake profiles. Theoretical intra-bone fractionation trends, modelled using lattice strain theory, concur with most REE data but some trends cannot be modelled using realistic boundary conditions. This fact, as well as the occurence of positive and negative Ce anomalies within the same fossil sample, hint towards changing REE compositions of diagenetic fluids over the timescales of REE uptake. Because apparent Ce anomalies frequently evolve over bone profiles and Ce anomalies can be inherited from previous fractionation events, Ce anomalies are a highly ambiguous tracer for constraining ambient redox conditions. In general, bioapatite REE signatures may not always reliably reflect ambient taphonomic or redox conditions and diagenetic fluid compositions. Therefore REE patterns and Ce anomalies of fossil bones must be interpreted cautiously as they vary spatially within skeletal remains and are affected by intra-bone fractionation processes as well as changing compositions of the diagenetic fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V34A..03T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V34A..03T"><span id="translatedtitle">Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Partition Coefficients During High-Grade Metamorphism: Experiments, Realities, And Large Datasets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taylor, R.; Clark, C.; Kylander-Clark, A. R.; Hacker, B. R.</p> <p>2015-12-01</p> <p>For 15 years rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) partitioning between zircon and garnet has facilitated the coupling of U-Pb ages to metamorphism, particularly in the granulite facies. The combination of in situ analysis and rapid data acquisition, particularly through combined techniques such as laser ablation split stream (LASS), means that complex terranes can be interrogated with increasing detail. However this detail provided by large datasets must also be combined with an understanding of the processes involved, for example the relative mobility of the REE, Ti, U and Pb within zircon grains that have withstood intense P-T conditions to varying degrees. Care must also be taken in identifying open system conditions, for example the presence or passage of partial melts that result in non-equilibrium, or very localised equilibrium, between the phases of interest. Visualisation of REE partition coefficients (DREE) becomes more complex with large datasets particularly when dealing with variably recrystallised zircon grains or multiple generations of garnet. Simple methods of visualising the important partitioning parameters identify temperature trends in experimental datasets [1, 2]. These trends can be used as clear indicators of zircon growing or recrystallizing in the presence of stable garnet and may be used as thermometers for zircon growth and for the identification of thermal peaks. Investigation of zircon-garnet DREE values in both long-lived high grade terranes (e.g. S. India), and complex polymetamorphic terranes (e.g. Enderby Land, E. Antarctica) provides insight into how partitioning information can be carefully interrogated, by looking at systematic or erratic variations from experimental data, even when dealing with issues such as variably recrystallised zircon and melt migration. Rubatto and Hermann, (2007). Chemical Geology. Taylor et al., (2015). Journal Metamorphic Geology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MARH17010C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MARH17010C"><span id="translatedtitle">Nernst-Ettingshausen Effect in <span class="hlt">Elemental</span> Rare-<span class="hlt">Earth</span> Single Crystals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chamoire, Audrey; Heremans, Joseph</p> <p>2012-02-01</p> <p>The transverse Nernst-Ettingshausen (N-E) coefficient N measurements of the <span class="hlt">elemental</span> rare-<span class="hlt">earth</span> (R-E) single-crystal are for the first time presented from 80 to 420 K. Since they have mainly hexagonal symmetry at room temperature, measurements are given with the heat flux along the [100] and the [001] axes. Due to their complex band structure and Fermi surface, their small thermopower (S) and their multicarrier systems involving electron (e) and hole (h) pockets, their N are expected to be large. Indeed, for such systems, both S and N can be expressed as^1 S=(Seσe+ Shσh)/( σe+σh) while N=[(Neσe+ Nhσh)( σe+σh)+(Sh-Se)(RHhσh- RHeσe)σeσh]/( σe+σh)^a, where σ is the electrical conductivity and RH the Hall coefficient and the subscript correspond to either carriers. Since Sh>0 and Se<0, the resulting S should be low thus leading to a large N . These solids are useful in single-material thermoelectric N-E coolers. They create a large temperature differences using thermomagnetic effects, without having to be cascaded. This would resolve th problem of contact resistances of actual multi-stage Peltier coolers, especially in the cryogenic temperature range. The dimensionless figure of merit of N-E coolers is zTN=B^2N^2σ(B)T/κ(B), with B is the magnetic field, T the absolute temperature and κ the thermal conductivity. a.E.H. Putley, The Hall Effect and Semiconductor Physics , New York: Dover publication, 1968.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018287','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018287"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in geological and synthetic samples using synchrotron X-ray fluorescence analysis</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.R.; Chao, E.C.T.; Back, J.M.; Minkin, J.A.; Rivers, M.L.; Sutton, S.R.; Cygan, G.L.; Grossman, J.N.; Reed, M.J.</p> <p>1993-01-01</p> <p>The concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in specific mineral grains from the Bayan Obo ore deposit and synthetic high-silica glass samples have been measured by synchrotron X-ray fluorescence (SXRF) analysis using excitation of the REE K lines between 33 and 63 keV. Because SXRF, a nondestructive analytical technique, has much lower minimum detection limits (MDLs) for REEs, it is an important device that extends the in situ analytical capability of electron probe microanalysis (EPMA). The distribution of trace amounts of REEs in common rock-forming minerals, as well as in REE minerals and minerals having minor quantities of REEs, can be analyzed with SXRF. Synchrotron radiation from a bending magnet and a wiggler source at the National Synchrotron Light Source, Brookhaven National Laboratory, was used to excite the REEs. MDLs of 6 ppm (La) to 26 ppm (Lu) for 3600 s in 60-??m-thick standard samples were obtained with a 25-??m diameter wiggler beam. The MDLs for the light REEs were a factor of 10-20 lower than the MDLs obtained with a bending magnet beam. The SXRF REE concentrations in mineral grains greater than 25 ??m compared favorably with measurements using EPMA. Because EPMA offered REE MDLs as low as several hundred ppm, the comparison was limited to the abundant light REEs (La, Ce, Pr, Nd). For trace values of medium and heavy REEs, the SXRF concentrations were in good agreement with measurements using instrumental neutron activation analysis (INAA), a bulk analysis technique. ?? 1993.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993E%26PSL.119...53S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993E%26PSL.119...53S"><span id="translatedtitle">Evolution of the lithosphere beneath Oahu, Hawaii: rare <span class="hlt">earth</span> <span class="hlt">element</span> abundances in mantle xenoliths</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sen, Gautam; Frey, Frederick A.; Shimizu, Nobumichi; Leeman, William P.</p> <p>1993-08-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> contents of clinopyroxenes in Hawaiian mantle xenoliths from Oahu were determined with an ion microprobe. The analyzed xenoliths are from four vents of the alkali Honolulu Volcanics (HV). Three (Kaau, Pali and Kalihi—KPK) are located close to the caldera of the extinct Koolau shield volcano, and the fourth, Salt Lake Crater (SLC), is on the periphery of the shield volcano. Systematic differences exist in REE contents between clinopyroxenes of the KPK and SLC xenoliths: (1) KPK pyroxenes are typically zoned in REE contents whereas SLC pyroxenes are homogeneous, (2) the LREE-depleted (chondrite-normalized) patterns that characterize many of the KPK xenoliths are not found in SLC xenoliths, and (3) the convex-upward REE patterns that are characteristic of SLC xenoliths are not found in KPK xenoliths. Relative to abyssal peridotites, the LREE-depleted Hawaiian lherzolite pyroxenes (interpreted to be residual oceanic lithosphere) have higher contents of REE, Na 2O, TiO 2 and FeO, and more modal clinopyroxene. These LREE-depleted Hawaiian xenoliths represent deeper, less-depleted parts of the melting column, whereas the abyssal peridotites represent the uppermost, more strongly depleted part of the mantle. The spoon-shaped, LREE-enriched and convex-upward REE patterns in the xenoliths have resulted from metasomatic enrichment of the lithosphere caused by reaction with magmas that formed the Honolulu Volcanics. A model for the evolution of the oceanic lithosphere is presented in which fractures were the main mode of transport of the Honolulu Volcanics. Metasomatic enrichment resulted from interaction between percolating Honolulu Volcanics magmas and wallrock. The differences between SLC and KPK xenoliths are attributed to chromatographic fractionation effects: SLC xenoliths are postulated to have come from a greater depth where they equilibrated to a larger extent with the percolating magmas than the KPK rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP51C1092D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP51C1092D"><span id="translatedtitle">Carbonatite: A Geophysical investigation of a rare <span class="hlt">earth</span> <span class="hlt">element</span> terrane, eastern Mojave Desert, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denton, K. M.; Ponce, D. A.; Miller, D. M.; MacPherson-Krutsky, C. C.</p> <p>2013-12-01</p> <p>Geophysical investigations reveal gravity and magnetic anomalies related to a Proterozoic carbonatite terrane in the eastern Mojave Desert, host to one of the largest rare <span class="hlt">earth</span> <span class="hlt">element</span> carbonatite deposits in the world. The deposit is located near Mountain Pass, California and occurs in a north-northwest trending fault-bounded block that extends along the eastern parts of the Clarke Mountain Range, Mescal Range, and Ivanpah Mountains. This Early to Middle Proterozoic block is composed of a 1.7 Ga metamorphic complex of gneiss and schist intruded by a 1.4 Ga suite of ultrapotassic alkaline intrusive rocks that includes carbonatite. The intrusive suite (oldest to youngest) includes shonkinite, mesosyenite, syenite, quartz syenite, potassic granite, carbonatite, and late shonkinite dikes which are spatially and temporally associated with carbonatite intrusions and dikes. Regional geophysical data reveal that the carbonatite deposit occurs along a gravity high and the northeast edge of a prominent magnetic high with an amplitude of about 200 nanoteslas. More than 1400 gravity stations and over 200 physical property samples were collected to augment existing geophysical data and will be used to determine the geophysical and geologic setting that provide an improved structural interpretation of the eastern Mojave Desert carbonatite terrane. Physical properties of representative rock types in the area include carbonatite ore, syenite, shonkinite, gneiss, granite, and dolomite. Carbonatite intrusions typically have distinctive gravity, magnetic, and radiometric signatures because these deposits are relatively dense, contain magnetite, and are enriched in thorium or uranium. However, our results show that the main carbonatite body is essentially nonmagnetic. Thus, it is unlikely that carbonatite rocks are the source of the magnetic high associated with the Clark Mountain and Mescal Ranges. Instead, we suggest that weakly to moderately magnetic intrusive rocks or</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.126..455H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.126..455H"><span id="translatedtitle">Biogeochemical implications from dissolved rare <span class="hlt">earth</span> <span class="hlt">element</span> and Nd isotope distributions in the Gulf of Alaska</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.; Frank, Martin; Hathorne, Ed; Pisias, Nick</p> <p>2014-02-01</p> <p>Dissolved rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations and Nd isotope compositions were measured for surface waters and full water column profiles of the Gulf of Alaska (GoA), and compared to water mass properties and circulation in order to better understand the mechanisms controlling the input and transport of REEs in the ocean. The REEs display a typical open-ocean range of concentrations (i.e., La: 12-66 pM; Lu: 0.2-2.5 pM) and depth distributions (i.e., surface ocean depletion and enrichment with water depth). Nd isotope signatures are highly radiogenic, as expected for the North Pacific margin (ranging from -3.8 to +0.2 ɛNd). The most radiogenic values were found in the coastal waters but also in the cores of eddies, indicating efficient export of REEs from the margins and across the mixed layer. This is the first time that distinct Nd isotope distributions in near surface waters can be directly assigned to offshore eddy transport. A distinct mid-depth (˜2200 m) Nd isotope signal was found that most likely reflects advection of a water mass that formed through past down-welling in the Northern Pacific. Subsurface Nd isotope compositions appear to behave conservatively and can be explained through a REE distribution model proposed here. This model is based on multivariate analysis of the REEs and invokes two distinct “pools” of dissolved REEs: a “passive pool” complexed by carbonate ions, and a “bio-reactive pool” that is microbially manipulated. The latter “pool” is only significant in the upper water column and most likely reflects the indirect effects of microbial cycling of iron. Our model of the open ocean REE distribution contributes to explaining the conservative nature of Nd isotopes and provides a mechanism linking surface ocean and pore water REE dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20110012866&hterms=Sulfur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSulfur','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20110012866&hterms=Sulfur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSulfur"><span id="translatedtitle">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="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</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>2010-01-01</p> <p>The presence of sulfur mass-independent fractionation (S-MIF) in sediments more than 2.45 x 10(exp 9) years old is thought to be evidence for an early anoxic atmosphere. Photolysis of sulfur dioxide (SO2) by UV light with lambda < 220 nm has been shown in models and some initial laboratory studies to create a S-MIF; however, sulfur must leave the atmosphere in at least two chemically different forms to preserve any S-MIF signature. Two commonly cited examples of chemically different sulfur species that could have exited the atmosphere are <span class="hlt">elemental</span> sulfur (S8) and sulfuric acid (H2S04) aerosols. Here, we use real-time aerosol mass spectrometry to directly detect the sulfur-containing aerosols formed when SO2 either photolyzes at wavelengths from 115 to 400 nm, to simulate the UV solar spectrum, or interacts with high-energy electrons, to simulate lightning. We found that sulfur-containing aerosols form under all laboratory conditions. Further, the addition of a reducing gas, in our experiments hydrogen (H2) or methane (CH4), increased the formation of S8. With UV photolysis, formation of S8 aerosols is highly dependent on the initial SO2 pressure; and S8 is only formed at a 2% SO2 mixing ratio and greater in the absence of a reductant, and at a 0.2% SO2 mixing ratio and greater in the presence of 1000 ppmv CH4. We also found that organosulfur compounds are formed from the photolysis of CH4 and moderate amounts of SO2, The implications for sulfur aerosols on early <span class="hlt">Earth</span> are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Icar..229..236J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Icar..229..236J"><span id="translatedtitle">On the non-uniform distribution of the angular <span class="hlt">elements</span> of near-<span class="hlt">Earth</span> objects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>JeongAhn, Youngmin; Malhotra, Renu</p> <p>2014-02-01</p> <p>We examine the angular distributions of near-<span class="hlt">Earth</span> objects (NEOs) which are often regarded as uniform. The apparent distribution of the longitude of ascending node, Ω, is strongly affected by well-known seasonal effects in the discovery rate of NEOs. The deviation from the expected π-periodicity in the apparent distribution of Ω indicates that its intrinsic distribution is slightly enhanced along a mean direction, Ω‾=111°; approximately 53% of NEOs have Ω values within ±90° of Ω‾. We also find that each subgroup of NEOs (Amors, Apollos and Atens) has different observational selection effects which cause different non-uniformities in the apparent distributions of their arguments of perihelion ω, and longitudes of perihelion ϖ. For their intrinsic distributions, our analysis reveals that the Apollo asteroids have non-uniform ω due to secular dynamics associated with inclination-eccentricity-ω coupling, and the Amors’ ϖ distribution is peaked towards the secularly forced eccentricity vector. The Apollos’ ω distribution is axial, favoring values near 0° and 180°; the two quadrants centered at 0° and 180° account for 55% of the Apollos’ ω values. The Amors’ ϖ distribution peaks near ϖ‾=4°; 61% of Amors have ϖ within ±90° of this peak. We show that these modest but statistically significant deviations from uniform random distributions of angular <span class="hlt">elements</span> are owed to planetary perturbations, primarily Jupiter’s. It is remarkable that this strongly chaotic population of minor planets reveals the presence of Jupiter in its angular distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11757853','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11757853"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> content in various waste ashes and the potential risk to Japanese soils.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, F S; Yamasaki, S; Kimura, K</p> <p>2001-11-01</p> <p>Selected chemical characteristics of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in 89 waste ash samples, including food scrap ashes (FSA), animal waste ashes (AWA), horticulture waste ashes (HWA), sewage sludge ashes (SSA) and incinerator bottom ashes (IBA), were examined in this study. The results showed that Y, La, Ce, Pr, Nd, Dy, Yb, Ho, Er, Tm, Lu in the waste ash samples were normally distributed, but Sc, Sm, Eu, Gd, Tb were not. Average REE concentrations followed the sequence of Ce > La = Y> Sc>Nd>Sm>Pr>Gd>Dy>Eu>Tb>Er> Yb>Ho>Lu>Tm. Of the five types of waste ashes, total REE contents (sigmaREE) ranged from 54 to 130 mg/kg, following the sequence of SSA>HWA>IBA>AWA>FSA; individual REE concentrations were within 0.04-20, 0.1-29, 0.2-33, 0.1-44 and 0.01-41 mg/kg for FSA, AWA, HWA, SSA and IBA, respectively. Crust-normalized REE patterns indicated that SSA was enriched with Sc, Sm, Eu, Gd, Tb and slightly enriched with La, Ce; IBA was enriched with Eu, Tb and slightly with La, Y, Ce; FSA was slightly enriched with Sm, Eu, Tb; REEs were not found to be elevated in HWA and AWA. Comparison of REE content in the waste ashes and in six principal Japanese agricultural soils indicated that application of FSA, AWA and HWA to agricultural land will cause no REE problem, but continuous application of SSA or IBA may cause Sc, Sm or Eu accumulation in some of the soils. PMID:11757853</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25957938','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25957938"><span id="translatedtitle">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.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gutiérrez-Gutiérrez, Silvia C; Coulon, Frédéric; Jiang, Ying; Wagland, Stuart</p> <p>2015-08-01</p> <p>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±6mgkg(-1) for REEs comprising 44±8mgkg(-1) for light REEs, 11±2mgkg(-1) for heavy REEs and 3±1mgkg(-1) for Scandium (Sc) and 3±1.0mgkg(-1) of PGMs. Compared to the typical concentration in ores, these concentrations are too low to achieve a commercially viable extraction. However, content of other highly valuable metals (Al and Cu) was found in concentrations equating to a combined value across the four landfills of around $400 million, which increases the economic viability of landfill mining. Presence of critical metals will mainly depend on the type of waste that was buried but the recovery of these metals through landfill mining is possible and is economically feasible only if additional materials (plastics, paper, metallic items and other) are also recovered for reprocessing. PMID:25957938</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24816778','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24816778"><span id="translatedtitle">PQQ-dependent methanol dehydrogenases: rare-<span class="hlt">earth</span> <span class="hlt">elements</span> make a difference.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Keltjens, Jan T; Pol, Arjan; Reimann, Joachim; Op den Camp, Huub J M</p> <p>2014-01-01</p> <p>Methanol dehydrogenase (MDH) catalyzes the first step in methanol use by methylotrophic bacteria and the second step in methane conversion by methanotrophs. Gram-negative bacteria possess an MDH with pyrroloquinoline quinone (PQQ) as its catalytic center. This MDH belongs to the broad class of eight-bladed β propeller quinoproteins, which comprise a range of other alcohol and aldehyde dehydrogenases. A well-investigated MDH is the heterotetrameric MxaFI-MDH, which is composed of two large catalytic subunits (MxaF) and two small subunits (MxaI). MxaFI-MDHs bind calcium as a cofactor that assists PQQ in catalysis. Genomic analyses indicated the existence of another MDH distantly related to the MxaFI-MDHs. Recently, several of these so-called XoxF-MDHs have been isolated. XoxF-MDHs described thus far are homodimeric proteins lacking the small subunit and possess a rare-<span class="hlt">earth</span> <span class="hlt">element</span> (REE) instead of calcium. The presence of such REE may confer XoxF-MDHs a superior catalytic efficiency. Moreover, XoxF-MDHs are able to oxidize methanol to formate, rather than to formaldehyde as MxaFI-MDHs do. While structures of MxaFI- and XoxF-MDH are conserved, also regarding the binding of PQQ, the accommodation of a REE requires the presence of a specific aspartate residue near the catalytic site. XoxF-MDHs containing such REE-binding motif are abundantly present in genomes of methylotrophic and methanotrophic microorganisms and also in organisms that hitherto are not known for such lifestyle. Moreover, sequence analyses suggest that XoxF-MDHs represent only a small part of putative REE-containing quinoproteins, together covering an unexploited potential of metabolic functions. PMID:24816778</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GeCoA..89....1M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeCoA..89....1M"><span id="translatedtitle">Aluminium competitive effect on rare <span class="hlt">earth</span> <span class="hlt">elements</span> binding to 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>Marsac, Rémi; Davranche, Mélanie; Gruau, Gérard; Dia, Aline; Bouhnik-Le Coz, Martine</p> <p>2012-07-01</p> <p>Competitive mechanisms between rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) and aluminium for humic acid (HA) binding were investigated by combining laboratory experiments and modeling to evaluate the effect of Al on REE-HA complexation. Results indicates that Al3+ competes more efficiently with heavy REE (HREE) than with light REE (LREE) in acidic (pH = 3) and low REE/HA concentration ratio conditions providing evidence for the Al high affinity for the few HA multidentate sites. Under higher pH - 5 to 6 - and high REE/HA conditions, Al is more competitive for LREE suggesting that Al is bound to HA carboxylic rather than phenolic sites. PHREEQC/Model VI Al-HA binding parameters were optimized to simulate precisely both Al binding to HA and Al competitive effect on REE binding to HA. REE-HA binding pattern is satisfactorily simulated for the whole experimental conditions by the ΔLK1A optimization (i.e. ΔLK1A controls the distribution width of log K around log KMA). The present study provides fundamental knowledge on Al binding mechanisms to HA. Aluminium competitive effect on other cations binding to HA depends clearly on its affinity for carboxylic, phenolic or chelate ligands, which is pH dependent. Under circumneutral pH such as in natural waters, Al should lead to LREE-depleted patterns since Al is expected to be bound to weak HA carboxylic groups. As deduced from the behavior of Al species, other potential competitor cations are expected to have their own competitive effect on REE-HA binding. Therefore, in order to reliably understand and model REE-HA patterns in natural waters, a precise knowledge of the exact behavior of the different REE competitor cations is required. Finally, this study highlights the ability of the REE to be used as a “speciation probe” to precisely describe cation interactions with HA as here evidenced for Al.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014MinDe..49..967H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014MinDe..49..967H&link_type=ABSTRACT"><span id="translatedtitle">The rare <span class="hlt">earth</span> <span class="hlt">element</span> potential of kaolin deposits in the Bohemian Massif (Czech Republic, Austria)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Höhn, S.; Frimmel, H. E.; Pašava, J.</p> <p>2014-12-01</p> <p>Four kaolin deposits in the Bohemian Massif were studied in order to assess the potential for the recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) as by-products from the residue after extraction and refining of the raw kaolin. The behaviour of REE + Y during kaolinitization was found to be largely a function of pre-alteration mineralogy. In the examples studied, i.e. granite-derived deposits of Kriechbaum (Austria) and Božičany, and arkose-derived deposits of Kaznějov and Podbořany (all Czech Republic), the REE + Y are predominantly hosted by monazite which has remained unaffected by kaolinitization. The overall REE + Y content of the variably kaolinitized rocks is strongly dependent on their genesis. While ion adsorption plays only a minor role in the concentration of REE + Y in the studied kaolinitized rocks, the processing and refining of the raw kaolin leads to residues that are enriched in REE + Y by a factor of up to 40. The use of a magnetic separator and a hydrocyclone in the processing of the raw material can yield REE + Y contents of as much as 0.77 wt%. Although this value compares well with the REE + Y concentration in some potentially economic REE + Y projects elsewhere, the overall tonnage of the (REE + Y)-enriched residue is by far not sufficient to consider economic extraction of REE + Y as by-product. Our results are most probably applicable also to other kaolin deposits derived from the weathering of Hercynian basement granites elsewhere (e.g. in Saxonia and Bavaria, Germany). Overall, the potential for REE + Y production as by-product from kaolin mining has to be regarded as minimal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25762379','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25762379"><span id="translatedtitle">Determination of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Human Sperm and Association with Semen Quality.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marzec-Wróblewska, Urszula; Kamiński, Piotr; Łakota, Paweł; Ludwikowski, Grzegorz; Szymański, Marek; Wasilow, Karolina; Stuczyński, Tomasz; Buciński, Adam; Jerzak, Leszek</p> <p>2015-08-01</p> <p>The aim of the present study was to measure lanthanum (La), cerium (Ce), europium (Eu), and gadolinium (Gd) concentrations in human semen and correlate the results with sperm quality. The median semen content of La was 19.5 µg kg(-1) dry weight (dw) (range 2.27-269), of Ce was 41.9 µg kg(-1) dw (range 4.52 to 167), of Eu was 0.68 µg kg(-1) dw (range 0.06-1.95), of Gd was 3.19 µg kg(-1) dw (range 0.38-12.0), and of calcium (Ca) was 4063 mg kg(-1) dw (range 484-17,191). Concentrations of La, Ce, Eu, Gd, and Ca were significantly lower in nondrinkers' semen than in semen from drinkers. Significant differences were detected between La, Ce, Eu, Gd, and Ca concentrations in semen from nondrinkers and moderate drinkers. Concentrations of La, Ce, and Gd in semen of short-term smokers were significantly lower than those in extremely long-term smokers. Significant differences were also detected between La concentration in semen from a group of short-term smokers and that of a group of long-term smokers. Positive correlations were found between La, Ce, Eu, Gd, and Ca concentrations in semen. La, Ce, Gd, and Ca concentrations in semen were positively associated with progressive motility and percentage of normal spermatozoa. Positive correlations were found between Ca and sperm concentration. Concentrations of La, Ce, and Gd were negatively associated with sperm concentration, whilst Ca concentration was negatively associated with volume of ejaculate. At the examined level, La, Ce, Eu, and Gd did not affect sperm quality, whereas alcohol consumption and smoking might have increased the level of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in semen. PMID:25762379</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26727984','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26727984"><span id="translatedtitle">The Future of Using <span class="hlt">Earth</span>-Abundant <span class="hlt">Elements</span> in Counter Electrodes for Dye-Sensitized Solar Cells.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Briscoe, Joe; Dunn, Steve</p> <p>2016-05-01</p> <p>With limited global resources for many of the <span class="hlt">elements</span> that are found in some of the most common renewable energy technologies, there is a growing need to use "<span class="hlt">Earth</span>-abundant" <span class="hlt">elements</span> as a long-term solution to growing energy demands. The dye-sensitized solar cell has the potential to produce low-cost renewable energy, with inexpensive production and most components using <span class="hlt">Earth</span>-abundant <span class="hlt">elements</span>. However, the most commonly used material for the cell counter electrode (CE) is platinum, an extremely expensive and rare <span class="hlt">element</span>. A selection of the materials investigated as alternative CEs are discussed, including metal sulfides, oxides, carbides, and nitrides and carbon-based materials such as carbon nanotubes, graphene, and conductive polymers. As well as having the potential for lower cost, these materials can also produce more-efficient devices due to their high surface area and catalytic activity. Therefore, once issues such as stability have been studied in more detail and scale-up of production methods are considered, there is a very promising future for the replacement of Pt in DSSCs with lower-cost, <span class="hlt">Earth</span>-abundant alternatives. PMID:26727984</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4712701','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4712701"><span id="translatedtitle"><span class="hlt">Earth</span> Abides Arsenic Biotransformations</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhu, Yong-Guan; Yoshinaga, Masafumi; Zhao, Fang-Jie; Rosen, Barry P.</p> <p>2015-01-01</p> <p>Arsenic is the most prevalent environmental toxic <span class="hlt">element</span> and causes health problems throughout the world. The toxicity, mobility, and fate of arsenic in the environment are largely determined by its speciation, and arsenic speciation changes are driven, at least to some extent, by biological processes. In this article, biotransformation of arsenic is reviewed from the perspective of the formation of <span class="hlt">Earth</span> and the evolution of life, and the connection between arsenic <span class="hlt">geochemistry</span> and biology is described. The article provides a comprehensive overview of molecular mechanisms of arsenic redox and methylation cycles as well as other arsenic biotransformations. It also discusses the implications of arsenic biotransformation in environmental remediation and food safety, with particular emphasis on groundwater arsenic contamination and arsenic accumulation in rice. PMID:26778863</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AREPS..42..443Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AREPS..42..443Z"><span id="translatedtitle"><span class="hlt">Earth</span> Abides Arsenic Biotransformations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Yong-Guan; Yoshinaga, Masafumi; Zhao, Fang-Jie; Rosen, Barry P.</p> <p>2014-05-01</p> <p>Arsenic is the most prevalent environmental toxic <span class="hlt">element</span> and causes health problems throughout the world. The toxicity, mobility, and fate of arsenic in the environment are largely determined by its speciation, and arsenic speciation changes are driven, at least to some extent, by biological processes. In this article, biotransformation of arsenic is reviewed from the perspective of the formation of <span class="hlt">Earth</span> and the evolution of life, and the connection between arsenic <span class="hlt">geochemistry</span> and biology is described. The article provides a comprehensive overview of molecular mechanisms of arsenic redox and methylation cycles as well as other arsenic biotransformations. It also discusses the implications of arsenic biotransformation in environmental remediation and food safety, with particular emphasis on groundwater arsenic contamination and arsenic accumulation in rice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013Litho.172..192C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013Litho.172..192C&link_type=ABSTRACT"><span id="translatedtitle">Mineral chemistry of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> (REE) mineralization, Browns Ranges, Western Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cook, Nigel J.; Ciobanu, Cristiana L.; O'Rielly, Daniel; Wilson, Robin; Das, Kevin; Wade, Benjamin</p> <p>2013-07-01</p> <p>‘Green energy futures’ are driving unprecedented demand for Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE), underpinning significant exploration activity worldwide. Understanding how economic REE concentrations form is critical for development of exploration models. REE mineralisation in the Browns Ranges, Gordon Downs Region, Western Australia, comprises xenotime-dominant mineralisation hosted within Archaean to Palaeoproterozoic metasedimentary units (Browns Range Metamorphics). Mineralogical, petrographic and mineral-chemical investigation, including trace <span class="hlt">element</span> analysis by Laser-Ablation Inductively-Coupled Plasma Mass Spectroscopy, gives insights into the mineralogical distribution and partitioning of REE, and also provides evidence for the genetic evolution of the Browns Range REE mineralisation via a succession of hydrothermal processes. Two main REE-bearing minerals are identified: xenotime [(Y,REE)PO4], which is HREE selective; and subordinate florencite [(REEAl3(PO4)2(OH)6] which is LREE selective. Two morphological generations of xenotime are recognised; compositions are however consistent. Xenotime contains Dy (up to 6.5 wt.%), Er (up to 4.35 wt.%), Gd (up to 7.56 wt.%), Yb (up to 4.65 wt.%) and Y (up to 43.3 wt.%). Laser Ablation ICP-MS <span class="hlt">element</span> mapping revealed a subtle compositional zoning in some xenotime grains. LREE appear concentrated in the grain cores or closest to the initial point of growth whereas HREE, particularly Tm, Yb and Lu, are highest at the outer margins of the grains. The HREE enrichment at the outer margins is mimicked by As, Sc, V, Sr, U, Th and radiogenic Pb. Florencite is commonly zoned and contains Ce (up to 11.54 wt.%), Nd (up to 10.05 wt.%) and La (up to 5.40 wt.%) and is also notably enriched in Sr (up to 11.63 wt.%) and Ca. Zircon (which is not a significant contributor of REEs overall due to its low abundance in the rocks) is also enriched in REE (up to 13 wt.% ΣREE) and is the principal host of Sc (up to 0.8 wt.%). Early, coarse</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22066167','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22066167"><span id="translatedtitle">Microstructure and properties of 17-4PH steel plasma nitrocarburized with a carrier gas 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>Liu, R.L.; Yan, M.F.; Wu, Y.Q.; Zhao, C.Z.</p> <p>2010-01-15</p> <p>The effect of rare <span class="hlt">earth</span> addition in the carrier gas on plasma nitrocarburizing of 17-4PH steel was studied. The microstructure and crystallographically of the phases in the surface layer as well as surface morphology of the nitrocarburized specimens were characterized by optical microscope, X-ray diffraction and scanning tunneling microscope, respectively. The hardness of the surface layer was measured by using a Vickers hardness test. The results show that the incorporation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the carrier gas can increase the nitrocarburized layer thickness up to 55%, change the phase proportion in the nitrocarburized layer, refine the nitrides in surface layer, and increase the layer hardness above 100HV. The higher surface hardening effect after rare <span class="hlt">earth</span> addition is caused by improvement in microstructure an