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Sample records for earth element geochemistry

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

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

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

  2. Rare Earth Element Geochemistry of Atacama Desert Soils

    NASA Astrophysics Data System (ADS)

    Sutter, B.; Ewing, S.; Amundson, R.; McKay, C.

    2003-12-01

    The Atacama Desert of northern Chile is one of driest deserts in the world, with a hyper-arid climate that arguably has persisted since the Miocene. Soils in the driest parts of the Atacama record the effects of long-term hyperaridity, retaining atmospherically-derived elements in quantities rarely seen on Earth. Recent work has demonstrated that the hyper-arid environment allows Atacama soils to accumulate large amounts of sulfate (e.g., anhydrite, gypsum), nitrate (NaNO3), and chloride (halite) that result in radical volumetric expansion of the soil. Possible salt sources include eolian redistribution from Atacama playas and/or marine aerosols. The objective of this work is to examine the rare earth element (REE) geochemistry of Atacama soils in order to understand how these trace elements chemically behave as soil water decreases to nearly zero. Two soils developed on fluvial landforms were examined along a south to north transect (Copiapo to Yungay) that coincides with decreasing moisture levels ( 15mm to 2 mm yr-1, south to north). Both soils have likely been undergoing soil formation since the Plio-Pleistocene. REE mass balance determinations were conducted on both soils through a comparison to that of the granitic alluvium from which they formed. An apparent net loss of REE relative to the granitic alluvium (10 to 30% Yungay; 15 to 65% Copiapo) has been calculated for these soils. The apparent loss of REE in both soils suggests that REE have been removed by some process or they have been have been diluted by dust and aerosols that have lower REE levels. Atmospheric deposition of marine and non-marine salts is the likely cause for the net loss of REE in the most arid soil, while weathering and leaching losses are a likely cause in the more humid endmember. Salts of marine origin are known to have low REE levels. Chondrite-normalized REE diagrams of the soils and parent materials are examined to determine if variations in local parent materials are evident. Europium anomalies, La/Yb, Gb/Yb, and Sm/Nd ratios are also presented to assess variations between soil horizons and parent materials.

  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 Colomera and Weekeroo Station, formed when a molten Fe ball collided on a differentiated silicate regolith near the surface of an asteroid. Silicate fragments were mixed with molten Fe by the impact. Heat from molten Fe caused localized melting of feldspar + pyroxene + tridymite assemblage. The inclusions remained isolated from one another during subsequent rapid cooling.

  5. 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

  6. 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 (0.0000007-0.0000086) ratios of the studied fluorites suggest that they precipitated from fractionated ore-bearing fluids at a late stage of deposition. The microtherometric measurements of the primary inclusions show that the Nuba Mountains fluorites were formed at temperatures greater than 600 °C. These values along with the low salinity of the fluid inclusions indicates homogenize at moderate temperatures. Thus the studied fluorite probably formed during the late stages of pegmatite consolidation under magmatic-hydrothermal transition conditions supporting the previous conclusions from REE geochemistry.

  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 further indicative of an elevated O2 concentration in the Permo-Carboniferous open ocean, as proposed by others, in contrast to the depletion of O2 in the bottom water of the Phosphoria Sea itself. The oceanographic conditions under which the deposit accumulated were likely similar to conditions under which many sedimentary phosphate deposits have accumulated and to conditions under which many black shales that are commonly phosphate poor have accumulated. A shortcoming of several earlier studies of these deposits has resulted from a failure to examine the marine fraction of elements separate from the terrigenous fraction. ?? 2007 Elsevier Ltd. All rights reserved.

  8. Rare Earth Element Geochemistry of Angrites Northwest Africa 4590 and Northwest Africa 4801

    NASA Astrophysics Data System (ADS)

    Sanborn, M. E.; Wadhwa, M.

    2009-03-01

    We report ion microprobe analyses of rare earth element abundances in minerals of the plutonic angrites NWA 4590 and NWA 4801. Based on these results, implications are presented for the petrogenetic history of these two angrites and their relationships to other angrites.

  9. Rare Earth Element Geochemistry of the Shergottites LAR 12095, 12240, and 12011

    NASA Astrophysics Data System (ADS)

    Dunham, E.; Wadhwa, M.; Tucker, K.; Balta, J. B.; McSween, H. Y.

    2015-07-01

    REE geochemistry confirms pairing of shergottites LAR 12095 and LAR 12240, and of LAR 12011 with LAR 06319. Calculations of magmatic fO2 suggest that these shergottites originated from martian mantle sources with different redox conditions.

  10. Time of Formation of Earth and Mars Constrained by Siderophile Element Geochemistry and the Hafnium-182-Tungsten-182 Isotope System

    NASA Astrophysics Data System (ADS)

    Yu, Gang

    182Hf-182W chronometry is considered the most powerful tool to determine the formation timescale of the terrestrial planets. However, previous work employed oversimplified accretion and core formation models. The accretion and core formation models presented here for the 182W isotopic evolution in the mantles of the accreting Earth and Mars, can incorporate the core formation conditions constrained by siderophile element geochemistry and can be successfully applied to constrain the formation timescale of Earth and Mars. Elemental abundance analyses of the Allende meteorite and two martian meteorites lead to new estimates of core-mantle concentration ratios of Si, V, Cr and Mn for Earth and two distinct mantle Hf/W ratios for Mars respectively, and provide better constraints on the models. It is concluded that formation of the proto-Earth (87% of its present mass) has to complete rapidly in 10.7 +/- 2.5 Myr after the onset of the Solar System for a late (? 52 Myr) Moon-forming giant impact. The mean time of Mars' accretion is determined to be 3.6 +/- 0.1 Myr, meaning that Mars accretes to 95% of its present mass in 10.8 +/- 0.3 Myr after the formation of the Solar System. Therefore, Mars is not a planetary embryo, and Mars and proto-Earth may be formed on a similar timescale if a late Moon-forming giant impact is assumed. In contrast, if the Moon formed early at 30 Myr then it takes about 3 times longer to form the proto-Earth compared to Mars. A stochastic mantle stirring and sampling model was developed to investigate the evolution of W isotope heterogeneities in the mantles of Earth and Mars after accretion and core formation. Our results confirm the mantle stirring rate of 500 Myr constrained by the long-lived isotope systems in Earth and suggest that the mantle stirring rate in Mars is much slower (2 Ga). A new concept is developed: the core formation memory of a siderophile element. Siderophile elements are shown to have different capabilities in recording core formation history, a very important fact to consider in any core formation modeling.

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

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

  14. Rare-earth element geochemistry of the Samail Ophiolite near Ibra, Oman

    NASA Astrophysics Data System (ADS)

    Pallister, John S.; Knight, Roy J.

    1981-04-01

    Rare-earth element (REE) analyses of 68 rock and mineral separate samples from the Samail ophiolite clearly differentiate the various units of the ophiolite suite and indicate that the crustal suite is cogenetic, produced by crystal fractionation of basaltic magma in a spreading ridge magma chamber. Mantle peridotites are residual in rare-earth character, but cannot be clearly related to the overlying mafic rocks. Chromian spinel is probably insignificant in its effect on REE distribution during partial melting and crystal fractionation, as indicated by the low REE concentrations in chromitite from the Samail. Layered gabbro REE patterns are dominated by cumulus clinopyroxene and plagioclase. Large positive Eu anomalies demonstrate plagioclase accumulation. Modal mixing (mass balance) calculations reveal that most of these adcumulus gabbros have REE patterns that are the products of the REE concentrations of their constituent cumulus phases in the observed modal proportions; hence no appreciable REE-rich mesostasis is present. Such calculations also allow the prediction of mineral REE concentrations not actually determined by mineral separate analyses. Several high-level (noncumulus?) gabbros yield patterns with positive Eu anomalies suggesting relative plagioclase accumulation, probably due to liquid fractionation (filter pressing). Dike complex REE patterns show light rare-earth element depletions and are similar to, but not necessarily diagnostic of, midocean ridge basalt. They cluster at similar abundance levels; however, the absolute variation in abundance is large, indicative of modification by crystal fractionation. Calculations using partition coefficient data indicate that many dikes represent liquids that could have existed in equilibrium with cumulus minerals of the plutonic suite. Mineral separate REE data from layered cumulus gabbro of the Khafifah stratigraphic section reveal cryptic variation trends that are correlated with major element variation, in support of a long-lived (periodically replenished) magma chamber model (Pallister and Hopson, 1978, 1979, 1981). (Cryptic variation as used herein is defined as the change in mineral composition with respect to stratigraphic position.) The REE cryptic variation shows both direct and inverse correlation to major element variation, indicating that magmatic replenishment was complicated by changes in parent melt REE abundance. A crystal fractionation origin for the small plagiogranite bodies of the Ibra area is favored by REE modeling, although larger bodies (Dasir) may also be related to magmatic inclusion of roofrock with diabase level REE distribution (Gregory and Taylor, 1979).

  15. 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.

  16. 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

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Smedley, Pauline 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 whilst those from the metasediment are Na-Ca-Mg-Cl-HCO 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. The pH of groundwater samples circulating through granite is typically lower than that of groundwater in the metasediments, the range being 4.3 to 7.2 (median 5.7) and 4.7 to 8.0 (median 6.6) respectively. Rare earth element (REE) concentrations of 0.45 ?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 ?g/1 (1.6 ?m) total REEs. The REEs are strongly controlled by pH with higher levels in groundwaters of pH < 6. Chondrite-normalised profiles are light rare earth element (LREE) enriched compared to heavy rare earths (HREEs), with a common slight negative Eu anomaly: both features reflecting the compositions of their host rocks. REE profiles therefore appear to be controlled by water-rock interactions involving predominantly REE-enriched minerals. 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. REE compositions normalised to shale have flatter profiles, although many are slightly convex with higher normalised Sm, Eu, and Gd values. A few metasediment-derived waters with high total REE concentrations have LREE-enriched shale-normalised patterns. It is suggested that the bulk of the REEs in these few samples is colloidal rather than totally dissolved. Groundwaters from the metasediments have a notable depletion in Ce which is distinct from waters in the granite. This depletion is problematic in that it is difficult to see how redox processes could be the dominant control, since groundwaters from the metasediments are unlikely to be more oxidising than those from the granite. Likewise, variations in pH fail to totally explain the distinctions in Ce concentration and La/Ce ratios between the two water types. It is therefore suggested that the Ce contents are largely source-related rather than process-related. The observed REE compositions of granite- and metasedimentderived 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.

  19. 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.

  20. The Use of Lead Isotope and Rare Earth Element Geochemistry for Forensic Geographic Provenancing

    NASA Astrophysics Data System (ADS)

    Carey, A.; Darrah, T.; Harrold, Z.; Prutsman-Pfeiffer, J.; Poreda, R.

    2008-12-01

    Lead isotope and rare earth element composition of modern human bones are analyzed to explore their utility for geographical provenancing. DNA analysis is the standard for identification of individuals. DNA analysis requires a DNA match for comparison. Thus, DNA analysis is of limited use in cases involving unknown remains. Trace elements are incorporated into bones and teeth during biomineralization, recording the characteristics of an individual's geochemical environment. Teeth form during adolescence, recording the geochemical environment of an individual's youth. Bones remodel throughout an individual's lifetime. Bones consist of two types of bone tissue (cortical and trabecular) that remodel at different rates, recording the geochemical environment at the time of biomineralization. Cortical bone tissue, forming the outer surface of bones, is dense, hard tissue that remodels in 25-30 yrs. Conversely, trabecular bone tissue, the inner cavity of bones, is low density, porous and remodels in 2-5 years. Thus, analyzing teeth and both bone tissues allows for the development of a geographical time line capable of tracking immigration patterns through time instead of only an individual's youth. Geochemical isotopic techniques (Sr, O, C, N) have been used for geographical provenancing in physical anthropology. The isotopic values of Sr, C, O, N are predominantly a function of soil compositions in areas where food is grown or water is consumed. Application of these provenancing techniques has become difficult as an individual's diet may reflect the isotopic composition of foods obtained at the local grocer as opposed to local soil compositions. Thus, we explore the use of REEs and Pb isotopes for geographical provenancing. Pb and REEs are likely more reliable indicators of modern geographical location as their composition are high in bio-available sources such as local soils, atmospheric aerosols, and dust as opposed to Sr, C, O, N that are controlled by food and drinking water. Lead isotope and REE analysis of trabecular and cortical bone tissue of 60 femoral heads resected during hip replacement surgery at the Univ. of Roch. Medical Center were analyzed by a combination of TIMS and ICP-MS. Results show that Pb compositions are consistent with local soil with variable inputs from known environmental sources. Several samples demonstrate inputs from known environmental sources (e.g. Mississippi Valley ore) that was used in paint, solder, and US gasoline. Additionally, results suggest bioincorporation of Pb with isotopic composition consistent with that observed for Canadian gasoline aerosols. Immigrants included in the study show Pb compositions distinctly different than local residents.

  1. 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.

  2. 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

  3. 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 continued oxidation of Ce(III) to Ce(IV) in the estuary. Fractionation of the light-to-heavy REEs seems to take place, whereas the Y/Ho fractionation is unclear in the estuarine mixing zone.

  4. 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, M?n?ila deposit, REE, trace elements, pyrite The present paper deal with the mineralogy and trace elements geochemistry of sulphide deposits from M?n?ila mine field located in NE area of Eastern Carpathians Mountains (Romania). The mineralization occurs within metamorphic rocks of Tulghe? terrane, part of Crystalline-Mezozoic zone of the Eastern Carpathians. The metamorphic rocks in M?n?ila 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 M?n?ila 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 M?n?ila 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) behavior of these elements in pure silicate melts. The REE patterns of the ores are highly variable and do not appear to be related to the mineral compositions. This feature may reflect contributions from several factors involved in fluid formation, ore mineral deposition and post-depositional processes. The lack of a relation between major mineral composition and REE patterns suggests complex REE fractionation processes during the ore formation. This work was supported by the European Social Fund in Romania, under the responsibility of the Managing Authority for the Sectoral Operational Programme for Human Resources Development 2007-2013 (grant POSDRU/88/1.5/S/47646).

  5. 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.

  6. 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 rather than by organic matter. In both layers, REEs have no relationship with fine-grained phosphates, and during the weathering process, the REEs were not very mobile and were resistant to fractionation.

  7. The geochemistry of the volatile trace elements As, Cd, Ga, In and Sn in the Earths mantle: New evidence from in situ analyses of mantle xenoliths

    NASA Astrophysics Data System (ADS)

    Witt-Eickschen, G.; Palme, H.; O'Neill, H. St. C.; Allen, C. M.

    2009-03-01

    The abundances of 30 trace elements, including the volatile chalcophile/siderophile elements As, Cd, Ga, In and Sn were determined by laser ablation ICP-MS in minerals of 19 anhydrous and 5 hydrous spinel peridotite xenoliths from three continents. The majority of samples were fertile lherzolites with more than 5% clinopyroxene; several samples have major element compositions close to estimates of the primitive mantle. All samples have been previously analysed for bulk-rock major, minor and lithophile trace elements. They cover a wide range of equilibration temperatures from about 850 to 1250 C and a pressure range from 0.8 to 3.0 GPa. A comparison of results from bulk-rock analyses with concentrations obtained from combining silicate and oxide mineral data with modal mineralogy, gave excellent agreement, with the exception of As. Arsenic is the only element analysed that has high concentrations in sulphides. For all other elements sulphides can be neglected as host phases in these mantle rocks. The major host phase for Cd, In and Sn is clinopyroxene and if present, amphibole. Cadmium and In appear to behave moderately incompatibly during mantle melting similar to Yb. The data yield new and more reliable mantle abundances for Cd (35 7 ppb), In (18 3 ppb) and Sn (91 28 ppb). The In value is similar to the Mg and CI-normalized Zn abundance of the mantle, although In is cosmochemically more volatile than Zn. The high In content suggests a high content of volatile elements in general in proto-Earth material. The lower relative abundances of volatile chalcophile elements such as Cd, S, Se and Te might be explained by sulphide segregation during core formation. The very low relative abundances of volatile and highly incompatible lithophile elements such as Br, Cl and I, and also C, N and rare gases, imply loss during Earth accretion, arguably by collisional erosion from differentiated planetesimals and protoplanets.

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

    USGS Publications Warehouse

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

    1983-01-01

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

  9. 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-Schnberg, Dieter

    2014-02-01

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

  10. 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 clusters either through dietary deficiency of essential elements or dietary excess of toxic elements. (28K)Figure 1. Potential human exposure routes within the earth's geochemical cycle can come from a wide variety of both natural and anthropogenic sources. This chapter focuses on a somewhat narrower area of medical geochemistry: the study of mechanisms of uptake of earth materials by humans and animals and their reactions to these materials. In order for earth materials to affect health, they must first interact with the body across key interfaces such as the respiratory tract, gastrointestinal tract, skin, and eyes. In some way, all of these interfaces require the earth materials to interact chemically with water-based body fluids such as lung fluids, gastrointestinal fluids, saliva, or blood plasma.The primary goal of this chapter, co-authored by a geochemist and a toxicologist, is to provide both geochemists and scientists from health disciplines with an overview of the potential geochemical mechanisms by which earth materials can influence human health. It is clear that significant opportunities for advancement in this arena will require continued and increased research collaborations between geochemists and their counterparts in the health disciplines.

  11. 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)

  12. Trace element geochemistry of Archean volcanic rocks

    NASA Technical Reports Server (NTRS)

    Jahn, B.-M.; Shih, C.-Y.; Murthy, V. R.

    1974-01-01

    The K, Rb, Sr, Ba and rare-earth-element contents of some Archean volcanic rocks from the Vermilion greenstone belt, northeast Minnesota, were determined by the isotopic dilution method. The characteristics of trace element abundances, supported by the field occurrences and major element chemistry, suggest that these volcanic rocks were formed in an ancient island arc system.

  13. Shallow water redox conditions from Permian-Triassic boundary microbialites: The rare earth element and iodine geochemistry of carbonates from Turkey and South China

    NASA Astrophysics Data System (ADS)

    Loope, G.; Kump, L.

    2012-12-01

    Rare earths and yittrium (REY), iodine, and major elements are determined in two carbonate sections spanning the Permian-Triassic transition in Demirtas, Turkey and Cili, South China. We use major oxides to measure contamination associated with siliciclastics, Fe-oxides, and phosphates. Additionally, we employ Y/Ho ratio, La anomaly, and light rare earth element depletion to identify which samples preserve a seawater-like REY distribution. Despite siliciclastic input, we find the Permian-Triassic boundary microbialites in both sections contain a negative Ce anomaly (average Pr/Pr*=1.07) indicative of deposition in an oxic environment. These boundary microbialites have their base at the extinction horizon and are widespread within the Tethyan region. In the Cili section, the underlying Permian limestone also preserves a seawater-like REY signature with a negative Ce anomaly indicating that the water column was oxygenated both before and after the extinction event. The Permian limestone in the Demirtas section does not preserve a seawater-like REY distribution, so the absence of a Ce anomaly cannot be used to distinguish prevailing redox conditions during deposition. However, in these samples, we find the presence of a diverse Permian benthic community sufficient to identify deposition in an oxic environment. The geochemical evidence for a continuously oxic environment during the deposition of the boundary microbialite presented in this study strongly supports work done using ostracods as redox indicators within the boundary microbialite in South China. These microbialites have been proposed as a disaster facies caused by the exclusion of grazers. Although anoxia is one of the suggested mechanisms for the exclusion of grazers, we find that it is not supported by geochemical evidence.

  14. 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.

  15. 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.

  16. 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 ?REE 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 mixing and dilution of the geothermal fluids and may have lead to changes in the extent and nature of REE complexing.

  17. Trace element geochemistry of CR chondrite metal

    NASA Astrophysics Data System (ADS)

    Jacquet, Emmanuel; Paulhiac-Pison, Marine; Alard, Olivier; Kearsley, Anton T.; Gounelle, Matthieu

    2013-10-01

    We report trace element analyses by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of metal grains from nine different CR chondrites, distinguishing grains from chondrule interior ("interior grains"), chondrule surficial shells ("margin grains"), and the matrix ("isolated grains"). Save for a few anomalous grains, Ni-normalized trace element patterns are similar for all three petrographic settings, with largely unfractionated refractory siderophile elements and depleted volatile Au, Cu, Ag, S. All three types of grains are interpreted to derive from a common precursor approximated by the least-melted, fine-grained objects in CR chondrites. This also excludes recondensation of metal vapor as the origin of the bulk of margin grains. The metal precursors were presumably formed by incomplete condensation, with evidence for high-temperature isolation of refractory platinum-group-element (PGE)-rich condensates before mixing with lower temperature PGE-depleted condensates. The rounded shape of the Ni-rich, interior grains shows that they were molten and that they equilibrated with silicates upon slow cooling (1-100 K h-1), largely by oxidation/evaporation of Fe, hence their high Pd content, for example. We propose that Ni-poorer, amoeboid margin grains, often included in the pyroxene-rich periphery common to type I chondrules, result from less intense processing of a rim accreted onto the chondrule subsequent to the melting event recorded by the interior grains. This means either that there were two separate heating events, which formed olivine/interior grains and pyroxene/margin grains, respectively, between which dust was accreted around the chondrule, or that there was a single high-temperature event, of which the chondrule margin records a late "quenching phase," in which case dust accreted onto chondrules while they were molten. In the latter case, high dust concentrations in the chondrule-forming region (at least three orders of magnitude above minimum mass solar nebula models) are indicated.

  18. 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)

  19. 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 of geochemical data into the EarthChem database. As a community resource, EarthChem will address user concerns and respond to broad scientific and educational needs. EarthChem will hold yearly workshops, town hall meetings, and/or exhibits at major meetings. The group has established a two-tier committee structure to help ease the communication and coordination of database and IT issues between existing data management projects, and to receive feedback and support from individuals and groups from the larger geosciences community.

  20. Rare earth elements: end use and recyclability

    USGS Publications Warehouse

    Goonan, Thomas G.

    2011-01-01

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

  1. 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

  2. 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.

  3. Rare Earth Element Mines, Deposits, and Occurrences

    USGS Publications Warehouse

    Orris, Greta J.; Grauch, Richard I.

    2002-01-01

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

  4. Moving KML geometry elements within Google Earth

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  5. Mineral resource of the month: rare earth elements

    USGS Publications Warehouse

    U.S. Geological Survey

    2011-01-01

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

  6. 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.

  7. 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 counterparts, primarily reflecting abiotic and microbial deposition. Finally, I investigate the geodynamic mechanism responsible for rapid, oscillatory true polar wander (TPW) events proposed for the Neoproterozoic and Phanerozoic Earth on the basis of paleomagnetic data. Using geodynamic models, I demonstrate that elastic strength in the lithosphere and stable excess ellipticity of Earth's figure provided sufficient stabilization to return the pole to its original state subsequent to convectively-driven TPW.

  8. Trace element geochemistry of marine biogenic particulate matter

    SciTech Connect

    Collier, R.W.

    1981-02-01

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

  9. 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 ...

  10. Trace Element Geochemistry of Tissint, the Newest Shergottite Fall

    NASA Astrophysics Data System (ADS)

    Sanborn, M. E.; Wadhwa, M.; Balta, J. B.; McSween, H. Y.

    2012-09-01

    We report trace element abundances in individual mineral phases, as well as in the bulk rock, of Tissint with the goal of understanding its petrogenetic history in relation to the other known olivine-phyric shergottites.

  11. Trace element geochemistry: New technology for stratigraphic correlations and formation evaluation

    SciTech Connect

    Lord, C.J.

    1995-09-01

    New technology based on the trace element chemistry of rocks is being developed as a tool for mapping subsurface formations in oilfields. This technology can be used to map rock formations in areas where traditional techniques are inconclusive. Trace element geochemistry complements and enhances conventional tools such as biostratigraphy, petrology, and log analysis. Applications cover a broad array of topics including stratigraphic correlations, interpretation of well log responses, age dating, and investigations of reservoir rock properties. Current work is focusing on identifying trace element fingerprints that uniquely mark specific subsurface horizons. There is convincing evidence that trace element fingerprints retain their relative stratigraphic position even though the original mineralogy of the rock has been extensively altered. This means that many of the trace elements associated with specific subsurface rock strata remain in place and are simply transferred from the original mineral to a new (alteration product) mineral. The immobility of these elements is an important geochemical feature because virtually all of the rocks encountered in the petroleum industry are altered to some extent. The ability to {open_quotes}see through{close_quotes} alteration events and obtain information about the original rock is a key advantage of trace element geochemistry techniques.

  12. 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+).

  13. 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.

  14. 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+).

  15. The geochemistry of carbonatites revisited: Two major types of continental carbonatites and their trace-element signatures

    NASA Astrophysics Data System (ADS)

    Chakhmouradian, A.

    2009-04-01

    There have been several attempts to systematize the geochemistry of carbonatites, most recently by Samoilov (1984), Nelson et al. (1988), Woolley and Kempe (1989), and Rass (1998). These studies revealed a number of important geochemical characteristics that can be used to track the evolutionary history of these rocks, distinguish them from modally similar metamorphic parageneses, and aid in mineral exploration for rare earths, niobium and other resources commonly associated with carbonatites. Important breakthroughs in the understanding of carbonatite petrogenesis and numerous reports of new carbonatite localities made in the past two decades lay the ground for a critical re-assessment of the geochemistry of these rocks. A new representative database of whole-rock carbonatite analyses was compiled from the post-1988 literature and various unpublished sources. The database contains 820 analyses encompassing calcio-, magnesio- and ferrocarbonatites from 174 localities (ca. one-third of the total number of carbonatites known worldwide) reduced to ca. 350 analyses following the approach of Woolley and Kempe (1989). Carbonatites emplaced in oceanic settings (e.g., Cape Verde), ophiolite belts (e.g., Oman), or those of uncertain tectonic affinity (e.g., El Picacho in Mexico) were not included. Two major types of continental carbonatites can be distinguished on the basis of their geological setting and trace-element geochemistry: (1) carbonatites emplaced in rifts and smaller-scale extensional structures developed in stable Archean cratons or paleo-orogenic belts, and (2) carbonatites emplaced in collisional settings following the orogenesis. In both settings, the most common and best-studied type of carbonatite is calcite carbonatite (predominantly intrusive with a small percentage of extrusive occurrences), which accounts for 62% of the analyses included in the database. Both types of carbonatite are typically associated with alkaline silicate lithologies (meleigites, nepheline syenites, etc.), but those associated with type-1 rocks are typically Na-rich and silica-undersaturated, whereas type-2 carbonatites are associated with K-rich silica-saturated to undersaturated syenites. Type-1 carbonatites are notably different from their type-2 counterparts in showing higher abundances of high-field-strength elements (HFSE = Ti, Zr, Hf, Nb, Ta), Rb, U and V, but lower levels of Sr, Ba, Pb, rare-earth elements, F and S. Key element ratios are also different in the two carbonatite types; in particular, Rb/K, Nb/Ta, Zr/Hf and Ga/Al values are consistently higher in type-1 samples. Notably, some element ratios (e.g., Co/Ni and Y/Ho) are very similar in both groups. Type-2 carbonatites commonly show a 13C-depleted signature relative to the "primary carbonatite" range (Deines, 1989). The observed differences in geological setting and geochemistry indicate the existence of two distinct carbonatite sources in the subcontinental lithosphere: amphibole-bearing lherzolite producing type-1 rocks (cf. Chakhmouradian, 2006), and subducted oceanic crust (rutile-bearing eclogite?) yielding type-2 melts depleted in HFSE, but enriched in light carbon, large-ion-incompatible elements, F and S. References: Chakhmouradian, A.R. (2006) High-field-strength elements in carbonatitic rocks: Geochemistry, crystal chemistry and significance for constraining the sources of carbonatites. Chem. Geol., 235, 138-160. Deines, P. (1989) Stable isotope variations in carbonatites. In: Carbonatites: Genesis and Evolution (K. Bell, Ed.). Unwin Hyman, London, 301-359. Nelson, D.R., Chivas, A.R., Chappell, B.V. and McCulloch, M.T. (1988) Geochemical and isotopic systematic in carbonatites and implications for the evolution of ocean-island sources. Geochim. Cosmochim. Acta, 52, 1-17. Rass, I.T. (1998) Geochemical features of carbonatite indicative of the composition, evolution, and differentiation of their mantle magmas. Geochem. Int., 36, 107-116. Samoilov, V.S. (1984) Geochemistry of Carbonatites. Nauka, Moscow (in Russ.). Woolley, A.R. and Kempe, D.R.C. (1989) Carbonatites: nomenclature, average chemical compositions, and element distribution. In: Carbonatites: Genesis and Evolution (K. Bell, Ed.). Unwin Hyman, London, 1-14.

  16. Trace Element Geochemistry of Micaceous Xenoliths From Kimberley

    NASA Astrophysics Data System (ADS)

    Bell, D. R.; Gregoire, M.; le Roex, A.; Davis, P.

    2001-05-01

    Whole rock and mineral major and trace element compositions were determined by XRF, electron microprobe and solution- and laser ablation ICP-MS on a modally diverse suite of 15 micaceous xenoliths from the Kimberley kimberlites. The aim was to better define the chemical characteristics of the MARID and "glimmerite" suites of micaceous xenoliths and their relationships to metasomatized peridotites, megacrysts, kimberlites and orangeites. Among the micaceous xenoliths, mineral and WR compositions of the MARIDs (here defined as containing essential K-richterite) are more Fe-rich and Cr-poor than the glimmerites and cpx-glimmerites, with the exception of an evolved cc-ap-glimmerite. WR Mg#s of all but the latter (Mg# = 75) are in the range 86-91, making it very unlikely that these rocks represent liquid compositions. However, mineral trace element concentrations and "anomalies" on normalized diagrams vary depending upon coexisting phases, suggesting that mass balance considerations may be important. We focused on the REE in cpx, which in these samples is the dominant REE reservoir. This reveals higher concentrations and La/Yb in MARID than cpx-glimmerites, which together with isotopic differences between the groups supports previously proposed links between MARIDs and orangeites and between glimmerites and kimberlites, i.e., two distinct metasomatic episodes related to two types of kimberlite magmatism. However, failing a magmatic origin in eclogite source rocks, this scenario fails to account for the more evolved (e.g. Fe-rich) nature of MARID rocks. In contrast, a continuum in REE behavior in a wider suite of mantle materials allows construction of an alternate endmember model for the metasomatic suite beneath Kimberley. In this scenario, chemical and isotopic evolution of a single type of alkaline melt and associated wallrocks is envisaged, as protokimberlitic melts infiltrate the continental thermal boundary layer. The magmatic vein assemblages evolve from Cr-poor megacrysts, through the Granny Smith-glimmerite association to the MARID suite. Wallrocks evolve from the dunite-wehrlite association through diopside- and phlogopite-rich lherzolites (PP) to richterite- bearing assemblages (PKP). Calculated liquid REE patterns of primitive and more evolved liquids are reproduced in erupted kimberlites and evolved carbonate-rich sill kimberlites (e.g., Benfontein) respectively. This model however requires extensive isotopic exchange of the parental magma with old enriched mantle in order to generate the observed Sr, Nd and Pb isotopic compositions of some MARID rocks. Understanding Cretaceous metasomatism in the Kaapvaal craton appears to call for complex hybrid models and detailed study of diverse xenolith types. Initial trace element measurements of primary textured micas in depleted garnet harzburgites suggest no connection of this material to Cretaceous kimberlite or orangeite magmatism, supporting previous arguments for ancient mantle enrichment.

  17. 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

  18. 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.

  19. Anthropogenic Cycles of Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Du, X.; Graedel, T. E.

    2009-12-01

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

  20. Tipping elements in the Earth's climate system

    PubMed Central

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

    2008-01-01

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

  1. 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.

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

    PubMed

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

    2011-07-01

    Soil and plant samples were collected from the sunflower growing area in the west of Jilin province. A variety of ancillary methods were used to determine the soil element content. Then the rare earth elements geochemistry in soil was studied, and the correlation of REEs in this region with other elements and the quality of plant was investigated. The results show that, (1) REE content of the soil in Nong'an is relatively higher to those in Daan and Tongyu. Distribution pattern of rare earth elements in soil for the right tilt of the light rare earth enrichment patterns which is consistent with the national distribution pattern of rare earth elements; (2) REE contents in the three studying areas in the soil are different, and this primarily relates to the soil parent materials; (3) The REEs which positively correlate with soil available potassium are Se, Fe2O3, Ti, P, Mn, Cu, Zn, Cr, Mo, B, F. The protein content of sunflower seeds has a negative correlation with REE. With the exception of Lu, all REEs show a similar correlation. PMID:21922834

  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. 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.

  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. 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.

  7. 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.

  8. 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"

  9. 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.

  10. 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 (amphibole major elements; Thornber and others, 2008b) and 37 (210Pb; 210Pb/226Pa; Reagan and others, 2008) of U.S. Geological Survey Professional Paper 1750 (Sherrod and others, 2008). A brief overview of sample collection methods is given below as an aid to deciphering the tephra sample catalog. This is followed by an explanation of the categories of sample information (column headers) in table 1. A summary of the analytical methods used to obtain the geochemical data in this report introduces the presentation of major- and trace-element geochemistry of Mount St. Helens 2004?2005 tephra samples in tables 2?6. Rhyolite glass standard analyses are reported (Appendix 1) to demonstrate the accuracy and precision of similar glass analyses presented herein.

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

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

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

  13. 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.

  14. 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.

  15. 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 significantly to elevated REE concentrations in foraminifera. The most likely source of REE ions at this stage of enrichment is from bottom waters and from the remineralisation of oxide phases which are in chemical equilibrium with the bottom waters. As planktonic foraminifera are buried below the sediment-water interface redox-sensitive ion concentrations are adjusted within the shells depending on the pore-water oxygen concentration. The concentration of ions which are passively redox sensitive, such as REE3+ ions, is also controlled to some extent by this process. We infer that (a) the Nd isotope signature of bottom water is preserved in planktonic foraminifera and (b) that it relies on the limited mobility of particle reactive REE3+ ions, aided in some environments by micron-scale precipitation of MnCO3. This study indicates that there may be sedimentary environments under which the bottom water Nd isotope signature is not preserved by planktonic foraminifera. Tests to validate other core sites must be carried out before downcore records can be used to interpret palaeoceanographic changes.

  16. Microbial engineering of floc Fe and trace element geochemistry in a circumneutral, remote lake.

    PubMed

    Elliott, Amy V C; Warren, Lesley A

    2014-06-17

    Evaluation of lacustrine floc Fe, Pb, and Cd biogeochemistry over seasonal (summer, winter) and water column depth (metalimnetic, hypolimnetic) scales reveals depth-independent seasonally significant differences in floc Fe biominerals and trace element (TE: Pb, Cd) sequestration, driven by floc microbial community shifts. Winter floc [TE] were significantly lower than summer [TE], driven by declining abundance and reactivity of floc amorphous Fe((III))-(oxy)hydroxide (FeOOH) phases under ice ([FeOOH](summer) = 37-77 mgg(-1) vs [FeOOH](winter) = 0.3-7 mgg(-1)). Further, while high summer floc [FeOOH] was observed at both water column depths, winter floc was dominated by Fe((II)) phases. However, the observed seasonal change in the nature and concentrations of floc Fe-phases was independent of water column [Fe], O2, and pH and, instead, significantly correlated to floc bacterial community membership. Bioinformatic modeling (Unifrac, PCA analyses) of in situ and experimental microcosm results identified a temperature-driven seasonal turnover of floc microbial communities, shifting from dominantly putative Fe metabolisms within summer floc to wintertime ancillary Fe reducing and S metabolizing bacteria. This seasonal shift of floc microbial community functioning, significantly the wintertime loss of microbial Fe((II))-oxidizing capability and concomitant increases of sulfur-reducing bacteria, alters dominant floc Fe minerals from Fe((III)) to Fe((II)) phases. This resulted in decreased winter floc [TE], not predicted by water column geochemistry. PMID:24810706

  17. Trace-element geochemistry of Archean volcanic rocks and crystal growth in southwestern Abitibi Belt, Canada

    NASA Astrophysics Data System (ADS)

    Capdevila, R.; Goodwin, A. M.; Ujike, O.; Gorton, M. P.

    1982-08-01

    Trace-element geochemistry on 176 controlled samples in three adjoining Abitibi (2.7 b.y.) volcanic piles confirms the fundamental concept of Archean volcanic cycles composed of lower tholeiitic and upper calc-alkalic parts. The volcanic piles, each as much as 16 km thick, are either unicyclic or multicyclic. In the latter case, the cycles display secular geochemical trends. All the volcanic rocks studied are indicated to have come from mantle sources. A fundamental feature of Abitibi magma genesis is the simultaneous presence of both depleted and undepleted mantle sources. Abitibi tholeiitic basalts closely resemble modern mid-ocean ridge basalts. Abitibi calc-alkalic andesites and alkalic rocks are very similar to modern oceanic island-arc andesites and to some modern volcanic-arc high-K rocks, respectively. The principal constraints to geodynamic processes are interpreted in terms of pulsating migrating mantle diapirisma type of hot-spot tectonics mechanism involving a layered mantle responsible for the early tholeiitic (depleted mantle source) and later calc-alkalic (undepleted mantle source) parts, respectively, of the volcanic cycles. *Present address: Institut de Gologic, Universit de Rennes, Rennes, France

  18. 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.

  19. 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  2. Geochemistry of metallic trace elements in fumarolic condensates from Nicaraguan and Costa Rican volcanoes

    NASA Astrophysics Data System (ADS)

    Gemmell, J. Bruce

    1987-08-01

    Metallic trace-element composition of volcanic gas from Cerro Negro, Momotombo, San Cristbal, Telica and Masaya volcanoes in Nicaragua and Pos volcano in Costa Rica is indicated by analyses of fumarolic condensates for alkalis, alkaline earths, transition elements, precious metals, halogens and sulphate. The temperatures of the fumaroles varied from 85 to 852C. Element concentrations range from 10 4 to 10 -3 ppm. Statistical tests indicate that the trace-element constituents of the condensates are log-normally distributed. Although there are variations in element concentrations in individual condensates, the general order of decreasing elemental abundances in Nicaraguan and Costa Rican fumarolic gas is: Cl > SO 4 > certain igneous rock-forming elements (Si, Al, Fe, Ti) > F and alkalis (Li, Na, K) > alkaline earths (Mg, Ca, Ba) > Br and transition elements (Cr, Mn, Co, Ni, Cu, Zn) > other ore-forming elements (Mo, Cd, Sn, Pb) > semi-metals (As, Sb) > Sc, Hg, and precious metals (Au, Ag). Li, Mn, Cr, and Pb were found to be near or below detection limits in many of the condensates analyzed. SO 4, Ti, Al, K, Na, Zn, Sn, Cr, and Br all tend to decrease in abundance as mean fumarolic temperature between volcanoes decreases. The remaining elements remain constant in abundance or behave erratically. The metallic trace-element composition of the Nicaraguan and Costa Rican fumarolic condensates is very similar to condensates from subduction zone volcanoes around the Pacific margin and the Mediterranean. Metals in volcanic gas are postulated to have been transported as halogen, sulphate, and oxide compounds. Chloride and fluoride compounds are considered to be the primary transporters of metals in volcanic gas. Correlations between metal and halogen content vary considerably between volcanoes. Statistically significant correlations between metal content and both chlorine and bromine are found in the Cerro Negro and between metal content and bromine and fluorine in the Momotombo condensates. Metal-bearing compounds in volcanic gas are postulated from correlation matrices. Bromine, though seldom reported in condensates, is a minor but important constituent of volcanic gas with concentrations similar to those of fluorine. Metal-bromide compounds have higher volatilities than fluoride compounds and volatilities similar to chloride compounds. Significant correlations between bromine content and metal concentration suggests that bromide compounds play a role in the transportation of metals in volcanic gas.

  3. 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.

    2016-03-01

    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.

  4. 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. Biotechnol. Bioeng. 2016;113: 339-348. © 2015 Wiley Periodicals, Inc. PMID:26332985

  5. 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.

  6. 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.

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

    USGS Publications Warehouse

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

    1957-01-01

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

  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.

    2015-07-01

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

  9. Modeling rammed earth wall using discrete element method

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  10. 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.

  11. 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

  12. 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 of the aquifer matrix following organic matter degradation and redox processes including sulfate reduction (salinity: 0.2-36.6, Ba: 7-1630 nmol kg-1, Sr: 1.3-210 μmol kg-1, U: 0.3-18 nmol kg-1, Mn: 0.6-2600 nmol kg-1, Ca: 2.1-15.2 mmol kg-1, 226Ra 20-5120 dpm 100 L-1). However, there is no evidence in the spring geochemistry that deep marine groundwater within this reaction zone exchanges with the coastal ocean via spring discharge. Total submarine groundwater discharge rates calculated from radium tracers are 40-95 m3 m-1 d-1, with terrestrial discharge contributing 75 ± 25% of the total. Global estimates of chemical loading from karst subterranean estuaries suggest Sr and U fluxes are potentially 15-28% and 7-33% of total ocean inputs (8.2-15.3 mol y-1 and 4.0-7.7 mol y-1), respectively. Radium-226 inputs from karst subterranean estuaries are 34-50 times river inputs (6.7-9.9 × 1016 dpm y-1).

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

    SciTech Connect

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

    1992-01-01

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

  14. Evidence from Sardinian basalt geochemistry for recycling of plume heads into the Earth's mantle.

    PubMed

    Gasperini, D; Blichert-Toft, J; Bosch, D; Del Moro, A; Macera, P; Télouk, P; Albarède, F

    2000-12-01

    Up to 10 per cent of the ocean floor consists of plateaux--regions of unusually thick oceanic crust thought to be formed by the heads of mantle plumes. Given the ubiquitous presence of recycled oceanic crust in the mantle source of hotspot basalts, it follows that plateau material should also be an important mantle constituent. Here we show that the geochemistry of the Pleistocene basalts from Logudoro, Sardinia, is compatible with the remelting of ancient ocean plateau material that has been recycled into the mantle. The Sr, Nd and Hf isotope compositions of these basalts do not show the signature of pelagic sediments. The basalts' low CaO/Al2O3 and Ce/Pb ratios, their unradiogenic 206Pb and 208Pb, and their Sr, Ba, Eu and Pb excesses indicate that their mantle source contains ancient gabbros formed initially by plagioclase accumulation, typical of plateau material. Also, the high Th/U ratios of the mantle source resemble those of plume magmas. Geochemically, the Logudoro basalts resemble those from Pitcairn Island, which contain the controversial EM-1 component that has been interpreted as arising from a mantle source sprinkled with remains of pelagic sediments. We argue, instead, that the EM-1 source from these two localities is essentially free of sedimentary material, the geochemical characteristics of these lavas being better explained by the presence of recycled oceanic plateaux. The storage of plume heads in the deep mantle through time offers a convenient explanation for the persistence of chemical and mineralogical layering in the mantle. PMID:11130068

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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 strongest correlation is with lowermost mantle tomography, which is probably spurious. The most striking correlations are between mantle tomography and post-Pangean subducted slabs. The integrated locations of slabs correlate strongly with fast areas near the transition zone and the core-mantle boundary and with slow regions from 1022-1248 km depth. This seems to be consistent with the 'avalanching' downwellings which have been indicated by models of the mantle which include an endothermic phase transition at the 670-km discontinuity, although this is not a unique interpretation. Taken as a whole, these results suggest that slabs and associated cold downwellings are the dominant feature of mantle convection. Hotspot locations are no better correlated with lower mantle tomography than are ridge locations.

  20. Compositional and phase relations among rare earth element minerals

    NASA Technical Reports Server (NTRS)

    Burt, D. M.

    1990-01-01

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

  1. Highly siderophile elements: Constraints on Earth accretion and early differentiation

    NASA Astrophysics Data System (ADS)

    Righter, Kevin

    Highly siderophile elements (HSE: Re, Au, and the PGEs) prefer FeNi metal and sulfide phases over silicate melts and minerals (olivine, pyroxene, feldspar, etc.). In addition, three HSE—Re, Pt, and Os—are involved in radioactive decay schemes: 187Re → 187Os (beta decay) and 192Pt → 188Os (alpha decay). As a result, they have provided constraints on the conditions during establishment of the primitive upper mantle, and the conditions and timing of later mantle differentiation and evolution. Hypotheses proposed to explain HSE elemental and isotopic compositions in the primitive upper mantle include mantle-core equilibrium, outer core metal addition, inefficient core formation, and late accretion (the late veneer). All of these scenarios have problems or unresolved issues. Here a hybrid model is proposed to explain the HSE concentrations in the primitive mantle, whereby Au, Pd, and Pt concentrations are set by high-pressure and temperature metal-silicate equilibrium, and Re, Ru, Rh, Ir, and Os concentrations are set by late accretion of chondritic material that is added via oxidized vapor following a giant impact (post-core formation). Processes affecting the later HSE evolution of the mantle include (1) layering caused by fractionation and/or flotation of mantle phases such as olivine, chromite, and garnet, (2) addition of metal from the outer core, and (3) recycling of oceanic crust. Uncertainties about differences in composition between the upper and lower mantle make evaluation of processes in the first category uncertain, but both the second and third processes can explain some aspects of mantle Os isotope geochemistry. This is a review of the field over the past decade and reports not only progress in the field but also highlights areas where much work remains.

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

    USGS Publications Warehouse

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

    2000-01-01

    Trace element compositions were determined (by instrumental neutron activation analysis; INAA) in 30 samples of synsedimentary volcanic ash-derived tonsteins and detrital claystones from coal seams within the late Permian coal-bearing formation of eastern Yunnan and western Guizhou Provinces, China. The characteristics of trace-element geochemistry in the tonsteins can be distinguished from those of detrital claystones because of the former's unique volcanic-ash origin. The detrital claystones are characterized by their relatively high content of V, Ti, Sc, Cr, Co and Ni, relatively low content of Th and U, Th/U ratio, and small negative Eu anomaly (Eu/Eu* 0.63-0.93). Overall, these trace element characteristics are consistent with a mafic source similar to the composition of basalt rocks in the erosional region on the western edge of the study area. In contrast, the tonsteins are low in V, Ti, Sc, Cr, Co and Ni contents and have a high Th/U ratio with a distinct negative Eu anomaly (Eu/Eu* normally in the range of 0.2-0.4), consistent with a silicic magmatic source. Within the group of tonsteins, those from the lower section (P2.1) of the coal-bearing formation are relatively high in Ti, Zr, Hf, Nb, Ta and rare earth elements (REE), as compared to those from the middle and upper sections (P2.2+3). In trace-element discrimination diagrams (scatter plots) of Hf-Ta, Ti-Ta, Ti-V, Hf-Sc, Lu-Hf and Lu-Th, tonsteins from the P2.1 horizon always fall in isolated distribution areas, separate from the tonsteins of the P2.2+3 horizon. These results suggest that the source materials of tonsteins from the two separate horizons were probably derived from volcanic ash falls of two distinctly different natures. Based on a comparison of the concentrations and assemblages of trace elements between various magmatic rocks, the source materials of tonsteins from P2.1 horizon were mostly composed of calc-alkalic, silica-poor volcanic ash (similar to rhyodacitic magma), whereas those from P2.+3 were apparently more siliceous and K-rich (rhyolitic magma). Thus, tonsteins from the two different horizons are characterized by unique geochemical properties, which remain constant over a wide lateral extent. Integration of trace-elemental compositions with mineralogical and textural observations makes possible the establishment of tonstein stratigraphy, thus, facilitating more precise and reliable coal-seam correlations. (C) 2000 Elsevier Science B.V. All rights reserved.Trace element compositions were determined in 30 samples of synsedimentary volcanic ash-derived tonsteins and detrital claystones from coal seams within the late Permian coal-bearing formation of eastern Yunnan and western Guizhou Provinces, China. The characteristics of trace-element geochemistry in the tonsteins can be distinguished from those of detrital claystones because of the former's unique volcanic-ash origin. The detrital claystones are characterized by their relatively high content of V, Ti, Sc, CR, Co and Ni, relatively low content of Th and U, Th/U ratio, and small negative Eu anomaly.

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

    USGS Publications Warehouse

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

    2004-01-01

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

  4. 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 (particularly in trace <span class="hlt">element</span> abundances in the whole-rock and individual minerals) confirms that exposure to the arid desert environment results in only minimal weathering of samples, provided the exposure times are brief.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.B31E..05P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.B31E..05P"><span id="translatedtitle">Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span> of Matrix Glass from the Bedout Impact Structure,Canning Basin NW Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poreda, R. J.; Basu, A. R.; Chakrabarti, R.; Becker, L.</p> <p>2004-12-01</p> <p>We report on geochemical and petrographic analysis of separated matrix glass from Lagrange-1 and Bedout-1 drill cores that penetrated the Bedout structure offshore NW Australia. The results support the conclusion that the Bedout structure was produced by a a major ET impact at the end-Permian that generated shock melted glass and impact breccias (Becker et al., Science, v.304, p.1469, 2004) The Bedout structure is a 30 km, circular, 1.5 km uplifted basment high that occurs on the passive margin offshore NW Australia. The isolated feature, covered by 3 km of Triassic to Recent sediments,is not consistent with any typical volcanic province (i.e. arc or hotspot volcanism). This hypothesis is supported by the unique mineralogy and chemistry of the matrix glass. At Lagrange, major <span class="hlt">elements</span> crudely resemble low-K, Fe-Ti basalts while the trace <span class="hlt">element</span> patterns have two distinct signatures. The lower 250 m of Lagrange (3260 - 3010 m depth) have essentially flat REE and "spider" patterns that superficially resemble some E-MORB; a signal not typically found in arc, hotspot or continental margin settings. The upper 150 meters (3000 - 2850m) of Lagrange and the entire Bedout core (3030 - 3070m) have similar light REE-enriched patterns but low levels of alkalis, alkaline-<span class="hlt">earths</span> and high field strength <span class="hlt">elements</span>. Again, the chemistry is not consistent with an arc or hotspot setting, based on the low Ba and extremely low Sr (30-110 ppm) concentrations. Based on the geophysical, chemical and petrologic evidence, we hypothesize that the Bedout structure formed as the result` of an ET impact with Permian age rift margin basalts and continental sediment. The basalts did not completely melt as evidenced by the abundance of large (1 mm) An50 plagioclase,that exist as both crystalline plag and shock melted maskelynite. Plagioclase is the major repository of Sr in basalts and the lack of a plagioclase contribution to the melt glass is reflected in the low Sr abundance. Shock-transformed plagioclase glass that still retains the lath shape and chemistry of An50 are one of the major indicators of the impact origin for Bedout.</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 samples have distinct Eu anomalies ([Eu]/[Eu*]=1.65~2.86) and others show relatively indistinct Eu anomalies and smooth pattern ((La/Lu)cn=1.48~2.68). Commonly schists have relatively low REE contents (?REE=8~119 ppm) compared to those of other host rocks. Generally, most of the host rock samples have enriched REE contents. Also they have LREE enriched patterns ((La/Lu)cn =1.48~62.32) and various values of Eu anomalies ([Eu]/[Eu*]=0.27~2.87). Also host rocks have negative Ce anomalies ([Ce]/[Ce*])=0.78~0.96). Ce anomaly is used as paleoredox indicator. These Ce values indicate the relatively shallow water environment of late Archean and early Paleoproterozoic in Yishui county, the North China.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5563033','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5563033"><span id="translatedtitle">Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in hot brines (165 to 190 degree C) from the Salton Sea geothermal field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lepel, E.A.; Laul, J.C.; Smith, M.R.</p> <p>1988-01-01</p> <p>Rare-<span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations are important indicators for revealing various chemical fractionation processes (water/rock interactions) and source region <span class="hlt">geochemistry</span>. Since the REE patterns are characteristic of geologic materials (basalt, granite, shale, sediments, etc.) and minerals (K-feldspar, calcite, illite, epidote, etc.), their study in geothermal fluids may serve as a geothermometer. The REE study may also enable us to address the issue of groundwater mixing. In addition, the behavior of the REE can serve as analogs of the actinides in radioactive waste (e.g., neodymium is an analog of americium and curium). In this paper, the authors port the REE data for a Salton Sea Geothermal Field (SSGF) brine (two aliquots: port 4 at 165{degree}C and port 5 at 190{degree}C) and six associated core samples.</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://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 has led to a 40% increase in atmospheric CO2 concentrations, and the atmospheric redistribution of reactive nitrogen and accumulation in remote ecosystems. We note that if anthropogenic contributions to soil erosion and eolian dust are considered, anthropogenic fluxes of up to 62 <span class="hlt">elements</span> may surpass their corresponding natural fluxes. [1] Klee and Graedel (2004), Annu. Rev. Environ. Resour., 29, p. 69-107 [2] Sen and Peucker-Ehrenbrink (2012), Environ. Sci. Technol., dx.doi.org/10.1021/es301261x</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 Moulic, S.; Leshin, L. A.; Lveill, 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, Genevive; Snchez, Pablo Sobrn; Favot, Laurent; Cody, George; Steele, Andrew; Flckiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Isral, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Prez, Ren; Saccoccio, Muriel; Yana, Charles; Armiens-Aparicio, Carlos; Rodrguez, Javier Caride; Blzquez, Isaas Carrasco; Gmez, Felipe Gmez; Gmez-Elvira, Javier; Hettrich, Sebastian; Malvitte, Alain Lepinette; Jimnez, Mercedes Marn; Martnez-Fras, Jess; Martn-Soler, Javier; Martn-Torres, F. Javier; Jurado, Antonio Molina; Mora-Sotomayor, Luis; Caro, Guillermo Muoz; Lpez, Sara Navarro; Peinado-Gonzlez, Vernica; Pla-Garca, Jorge; Manfredi, Jos Antonio Rodriguez; Romeral-Planell, Julio Jos; Fuentes, Sara Alejandra Sans; Martinez, Eduardo Sebastian; Redondo, Josefina Torres; Urqui-O'Callaghan, Roser; Mier, Mara-Paz Zorzano; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairn, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Sullivan, Robert; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Gnther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanp, 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, Jrmie; Lee, Qiu-Mei; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schrder, Susanne; Toplis, Mike; Lewin, ric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Isral, Guy; Szopa, Cyril; Robert, Franois; Sautter, Violaine; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; Franois, Pascaline; Raulin, Franois; 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</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/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=24324274&dopt=AbstractPlus','TOXNETTOXLINE'); return false;" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=24324274&dopt=AbstractPlus"><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://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?TOXLINE">TOXLINE Toxicology Bibliographic Information</a></p> <p>McLennan SM; Anderson RB; Bell JF 3rd; Bridges JC; Calef F 3rd; Campbell JL; Clark BC; Clegg S; Conrad P; Cousin A; Des Marais DJ; Dromart G; Dyar MD; Edgar LA; Ehlmann BL; Fabre C; Forni O; Gasnault O; Gellert R; Gordon S; Grant JA; Grotzinger JP; Gupta S; Herkenhoff KE; Hurowitz JA; King PL; Le Moulic S; Leshin LA; Lveillé R; Lewis KW; Mangold N; Maurice S; Ming DW; Morris RV; Nachon M; Newsom HE; Ollila AM; Perrett GM; Rice MS; Schmidt ME; Schwenzer SP; Stack K; Stolper EM; Sumner DY; Treiman AH; VanBommel S; Vaniman DT; Vasavada A; Wiens RC; Yingst RA; MSL Science Team</p> <p>2014-01-24</p> <p>Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The <span class="hlt">geochemistry</span> of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6772393','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6772393"><span id="translatedtitle">Catalytic properties of monophosphates 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>Mel'nikov, P.P.; Koldasheva, E.M.; Kubason, A.A.; Lais Pichardo, Kh.</p> <p>1986-11-01</p> <p>From analysis of literature data it follows that use of structural analogies often leads to new catalytic systems. A characteristic example is zeolites and phosphates of group III <span class="hlt">elements</span> which have as basic structural unit the PO/sub 4/ tetrahedron. The catalytic properties of zeolites and phosphates are well known in transformations of ethanol. In this work the catalytic properties of the complex rare-<span class="hlt">earth</span> phosphates H/sub 3/HO (PO/sub 4/)/sub 2/, K/sub 2/CsTm(PO/sub 4/) /sub 2/, and K/sub 2/CsEr(PO/sub 4/) /sub 2/ in the above reaction are investigated, Phosphates containing rare-<span class="hlt">earth</span> an alkaline cations were obtained by the cryochemical method.</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; Ribeiro Guevara, S; 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 10pgg(-1), as well as measurement repeatability below 15%. Overall, the Na2O2/ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare <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://ntrs.nasa.gov/search.jsp?R=19850024768&hterms=crust+asthenosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcrust%2Basthenosphere','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850024768&hterms=crust+asthenosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcrust%2Basthenosphere"><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://ntrs.nasa.gov/search.jsp?R=19910053953&hterms=Zircon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%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%3D60%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> <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/2014ChPhB..23e7403J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ChPhB..23e7403J"><span id="translatedtitle">Magnetic property improvement of niobium doped with 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>Jiang, Tao; He, Fei-Si; Jiao, Fei; He, Fa; Lu, Xiang-Yang; Zhao, Kui; Zhao, Hong-Yun; You, Yu-Song; Chen, Lin</p> <p>2014-05-01</p> <p>A new idea is proposed by the PKU group to improve the magnetic properties of the Type-II superconductor niobium. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> like scandium and yttrium are doped into ingot niobium during the smelting processes. A series of experiments have been done since 2010. The preliminary testing results show that the magnetic properties of niobium materials have changed with different doping <span class="hlt">elements</span> and proportions while the superconductive transition temperature does not change very much. This method may increase the superheating magnetic field of niobium so as to improve the performance of the niobium cavity, which is a key component of SRF accelerators. A Tesla-type single-cell cavity made of scandium-doped niobium is being fabricated.</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> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/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 of the wall rock during faulting.</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://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://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.; Thiaudire, Dominique; Charbonnier, Sylvain; Clment, Gal; Bertrand, Loc</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/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; Thiaudire, Dominique; Charbonnier, Sylvain; Clment, Gal; Bertrand, Loc</p> <p>2014-01-01</p> <p>The interpretation of flattened fossils remains a major challenge due to compression of their complex anatomies during fossilization, making critical anatomical features invisible or hardly discernible. Key features are often hidden under greatly preserved decay prone tissues, or an unpreparable sedimentary matrix. A method offering access to such anatomical features is of paramount interest to resolve taxonomic affinities and to study fossils after a least possible invasive preparation. Unfortunately, the widely-used X-ray micro-computed tomography, for visualizing hidden or internal structures of a broad range of fossils, is generally inapplicable to flattened specimens, due to the very high differential absorbance in distinct directions. Here we show that synchrotron X-ray fluorescence spectral raster-scanning coupled to spectral decomposition or a much faster Kullback-Leibler divergence based statistical analysis provides microscale visualization of tissues. We imaged exceptionally well-preserved fossils from the Late Cretaceous without needing any prior delicate preparation. The contrasting <span class="hlt">elemental</span> distributions greatly improved the discrimination of skeletal <span class="hlt">elements</span> material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline <span class="hlt">earth</span> <span class="hlt">elements</span> and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Local quantification of rare <span class="hlt">earths</span> may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies. PMID:24489809</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H34C..02N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H34C..02N"><span id="translatedtitle">Source and mobility of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in a sedimentary aquifer system: Aquitaine basin (Southern France)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Negrel, P. J.; Petelet-Giraud, E.; Millot, R.; Malcuit, E.</p> <p>2011-12-01</p> <p>The study of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in natural waters initially involved an examination of their occurrence and behavior in seawater and coastal waters such as estuaries. Since the 1990s, REE <span class="hlt">geochemistry</span> has been applied to continental waters such as rivers and lakes and groundwaters. Rare <span class="hlt">earth</span> <span class="hlt">elements</span>) are of great interest because of their unique characteristics and have been used in the study of many geological processes like weathering and water-rock interaction processes, provenance of sediments, etc... With the evolution of analytical techniques like new generation ICP-MS, much attention had been paid towards the water <span class="hlt">geochemistry</span> of REEs. However, there is a need of more investigations devoted to REEs in large groundwater systems, especially on the understanding of the distribution of REEs and their evolution in such systems. In this frame, large sedimentary aquifer systems often constitute strategic water resources for drinking water supply, agriculture irrigation and industry, but can also represent an energetic resource for geothermal power. Large water abstractions can induce complete modification of the natural functioning of such aquifer systems. These large aquifer systems thus require water management at the basin scale in order to preserve both water quantity and quality. The large Eocene Sand aquifer system of the Aquitaine sedimentary basin was studied through various hydrological, chemical and isotopic tools. This system extends over 116,000 km2 in the South west part of the French territory. The aquifer being artesian in the west of the district and confined with piezometric levels around 250-m depth in the east. The 'Eocene Sands', composed of sandy Tertiary sediments alternating with carbonate deposits, is a multi-layer system with high permeability and a thickness of several tens of metres to a hundred metres. The Eocene Sand aquifer system comprises at least five aquifers: Paleocene, Eocene infra-molassic sands (IMS), early Eocene, middle Eocene, and late Eocene. One important feature, in these confined systems isolated from anthropogenic influence, is the range in salinities by a factor of 10, from 250 mg/L up to 2.5 g/L. The ?REE, in the range 2-54 ng/L, with a dependence on salinity when expressed in % HCO3 or SO4, reflect the carbonate or evaporite source of REEs. The UCC normalized-REE patterns show a large variability as exemplified by the REE flat patterns-low SREE associated with salinity controlled by HCO3. In the present work, the REEs are investigated in terms of saturation indices, speciation modelling, REE patterns in order to recognize the aquifer type hosting groundwater and decipher the origin of the salinity of the groundwater as some part of the aquifer display in the groundwater concentration of chemical <span class="hlt">element</span> exceeding the drinking water standard (SO4, F...). Such high concentrations of naturally-occurring substances (e.g. unaffected by human activities) can have negative impacts on groundwater thresholds and deciphering their origin by means of geochemical tools like REE is a remaining challenge.</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://adsabs.harvard.edu/abs/2005E%26PSL.239...79H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005E%26PSL.239...79H"><span id="translatedtitle">Revisiting the rare <span class="hlt">earth</span> <span class="hlt">elements</span> in foraminiferal tests [rapid communication</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haley, Brian A.; Klinkhammer, Gary P.; Mix, Alan C.</p> <p>2005-10-01</p> <p>Are the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in foraminifera a valuable proxy for use in paleoceanographic and climate change studies? In order to investigate this, we attempted a comprehensive study of REEs in planktonic and benthic foraminifera. Several different cleaning protocols were tested. Although the hydroxylamine used to clean all foraminifera in this study removes an unidentified source of REE contamination, it seems to remobilize metal oxides that are otherwise unaffected in flow-through dissolution. The calculated REE distribution coefficients, KD(REE)s, are between 100 and 500 for both planktonic and benthic foraminifera. These KDs are high compared to other <span class="hlt">elements</span> in biogenic calcite but can be explained through a general model of <span class="hlt">element</span> incorporation during foraminiferal calcification. From data taken from eight core tops in the southeast Pacific, we conclude that the REEs in planktonic foraminifera are, indeed, useful as a proxy for upper ocean water mass and mixed layer biogenic productivity. Alternatively, the REEs in benthic foraminifera are useful as a proxy for carbon flux to the sea floor. These proxies should be robust down core unless the sediments have undergone anoxic diagenesis, which stabilizes Fe carbonate thus overprinting the primary REE signature. However, it is clear from REE distributions in foraminiferal tests if anoxic conditions have occurred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850007334&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850007334&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth"><span id="translatedtitle">The chemistry of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the solar nebula</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Larimer, J. W.; Bartholomay, H. A.; Fegley, B.</p> <p>1984-01-01</p> <p>The high concentration of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in primitive CaS suggests that the REE along with the other normally lithophile <span class="hlt">elements</span> form stable sulfides under the unusual conditions which existed during the formation of enstatite chrondites. In order to acquire a more quantitative framework in which to interpret these data, the behavior of the REE in systems with solar, or slightly fractionated solar, composition is being studied. These new data introduce modest changes in the behavior of some of the REE when compared to previous studies. For example, the largest differences are in the stabilities of the gaseous monoxides of Ce, Eu, Tb, Ho, and Tm, all of which now appear to be less stable than previously thought, and YbO(g) which is somewhat more stable. Much more significant are the changes in REE distribution in the gas phase in fractionated systems, especially those made more reducing by changing the C/O ratio from the solar value of 0.6 to about 1.0. In almost all cases, the exceptions being Eu, Tm and Yb whose <span class="hlt">elemental</span> gaseous species dominate, the monosulfides become more abundant. Moreover, the solid oxides of Eu, Tm and Yb become less stable under more reducing conditions which, in effect, should reduce the condensation temperature of all REE in more reduced systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://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://www.ncbi.nlm.nih.gov/pubmed/23268141','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23268141"><span id="translatedtitle">Heavy metals, trace <span class="hlt">elements</span> and sediment <span class="hlt">geochemistry</span> at four Mediterranean fish farms.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kalantzi, I; Shimmield, T M; Pergantis, S A; Papageorgiou, N; Black, K D; Karakassis, I</p> <p>2013-02-01</p> <p>Trace <span class="hlt">element</span> concentrations in sediment were investigated at four fish farms in the Eastern Mediterranean Sea. Fish farms effects were negligible beyond 25-50 m from the edge of the cages. Based on <span class="hlt">elemental</span> distribution, sediments from the farms were separated into coarse oxidized and silty reduced ones. Fish feed is richer in P, Zn and Cd than reference and impacted stations. Comparison among impacted stations and the respective reference stations shows that, in anoxic sediments, all <span class="hlt">elements</span> had higher concentrations at the impacted stations than at reference stations while in oxic sediments, many <span class="hlt">elemental</span> concentrations were lower at impacted stations than at reference stations. The behavior of <span class="hlt">elements</span> and therefore their distribution is affected by changes in sediment grain size, organic content and redox regime. <span class="hlt">Elements</span> in sediments around fish farms can be clustered into five groups according to these environmental variables. In silty and anoxic sediments, <span class="hlt">element</span> concentrations were higher than in coarse and oxic ones. Several approaches were used to assess potential sediment toxicity (enrichment factors, geoaccumulation indices, contamination factors) as well as to assess the potential danger to aquatic life (Sediment Quality Guidelines, SQG). Cu, Zn and Fe can cause from threshold to extreme effects on aquatic life in anoxic, fine-grained sediments and As can cause threshold effects in all types of sediment around fish farms. Other <span class="hlt">elements</span> (Cr, Pb, Mn) can also cause unwanted effects when compounded with elevated background levels. PMID:23268141</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://adsabs.harvard.edu/abs/2015GeCoA.170...17B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.170...17B"><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 is probably best explained by preferential alteration of feldspars and/or accessory mineral phases. Importantly, this finding clearly indicates that silicate weathering can lead to decoupling of REE between different grain-size fractions, with implications for sediment provenance studies. Finally, we propose a set of values for a World River Average Clay (WRAC) and Average Silt (WRAS), which provide new estimates for the average composition of the weathered and eroded upper continental crust, respectively, and could be used for future comparison purposes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4156694','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4156694"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> activate endocytosis in plant cells</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, Lihong; Li, Jigang; Zhou, Qing; Yang, Guangmei; Ding, Xiao Lan; Li, Xiaodong; Cai, Chen Xin; Zhang, Zhao; Wei, Hai Yan; Lu, Tian Hong; Deng, Xing Wang; Huang, Xiao Hua</p> <p>2014-01-01</p> <p>It has long been observed that rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) regulate multiple facets of plant growth and development. However, the underlying mechanisms remain largely unclear. Here, using electron microscopic autoradiography, we show the life cycle of a light REE (lanthanum) and a heavy REE (terbium) in horseradish leaf cells. Our data indicate that REEs were first anchored on the plasma membrane in the form of nanoscale particles, and then entered the cells by endocytosis. Consistently, REEs activated endocytosis in plant cells, which may be the cellular basis of REE actions in plants. Moreover, we discovered that a portion of REEs was successively released into the cytoplasm, self-assembled to form nanoscale clusters, and finally deposited in horseradish leaf cells. Taken together, our data reveal the life cycle of REEs and their cellular behaviors in plant cells, which shed light on the cellular mechanisms of REE actions in living organisms. PMID:25114214</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993JGR....9820587S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JGR....9820587S"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> composition of precipitation, precipitation particles, and aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sholkovitz, Edward R.; Church, Thomas M.; Arimoto, Richard</p> <p>1993-11-01</p> <p>We report the rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) composition of aerosols and precipitation (dissolved and particle phases) from Bermuda, Lewes (Delaware), and Woods Hole (Massachusetts). There is large-scale fractionation of REEs between the continents, atmosphere, and the oceans. The REE compositions of atmospheric samples are highly fractionated relative to (1) each other (e.g., aerosol/precipitation pairs), (2) the upper crust of the <span class="hlt">Earth</span>, and (3) seawater. Precipitation samples exhibit markedly convex-up shale-normalized patterns, large negative Eu anomalies and large and systematic depletions in the heavy REE (Lu greater than Yb greater than Er greater than Dy). Aerosols are strongly depleted in the heavy REE which dissolutions experiments show are attributable to the presence of HREE-enriched refactory minerals. We argue that in situ selective dissolution of mineral aerosol particles is responsible for the unusual REE composition of precipitation. This has major implications for the interpretation of the biogeochemical cycles of REEs in the oceans, particularly the partitioning between solution and particle phases, residence times, and the composition of seawater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016379&hterms=Rare&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DRare','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016379&hterms=Rare&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DRare"><span id="translatedtitle">Rare <span class="hlt">Earth</span> <span class="hlt">elements</span> in individual minerals in Shergottites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wadhwa, Meenakshi; Crozaz, Ghislaine</p> <p>1993-01-01</p> <p>Shergottites (i.e., Shergotty, Zagami, EETA79001, ALHA77005, and LEW88516) are an important set of achondrites because they comprise the majority of the SNC group of meteorites (nine, in total, known to us), which are likely to be samples of the planet Mars. Study of these meteorites may therefore provide valuable information about petrogenetic processes on a large planetary body other than <span class="hlt">Earth</span>. Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) distributions between various mineral phases were found to be useful in geochemically modeling the petrogenesis of various rock types (terrestrial and meteoritic). However, with the exception of a few ion microprobe studies and analyses of mineral separates, there has previously not been any comprehensive effort to characterize and directly compare REE in individual minerals in each of the five known shergottites. Ion microprobe analyses were made on thin sections of each of the shergottites. Minerals analyzed were pyroxenes (pigeonite and augite), maskelynite, and whitlockite. The REE concentrations in each mineral type in each shergottite is given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Natur.523..293T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Natur.523..293T"><span id="translatedtitle"><span class="hlt">Earth</span> science: Big <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>Till, Christy</p> <p>2015-07-01</p> <p>A compilation of more than 300,000 rock compositions provides crucial input into a 100-year-old debate on how the continental crust formed, and provides new constraints for theories of continental-crust development. See Article p.301</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMPP13B2118M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMPP13B2118M"><span id="translatedtitle">Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span> of the Dolomite Member of the Neoproterozoic Ibex Formation, Death Valley National Park, CA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, E. E.; Lanids, J. D.; Quicksall, A. N.; Ddamba, I.</p> <p>2012-12-01</p> <p>This work examines the major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the pink, laminated Dolomite Member of the Neoprotoerozic Ibex Formation, sampled at high resolution in the Ibex Hills of Death Valley, California. The Dolomite Member of the Ibex Formation directly overlies a basal conglomerate which has lead Corsetti and Kaufman (2005) to speculate that the juxtaposition of these units represents a diamictite - cap carbonate pair. Cap carbonates are inferred to represent deposition under high alkalinity conditions in the shallow ocean at the termination of low latitude glaciation. Increased alkalinity may be driven by the post glacial overturn of anoxic water masses. Here we infer paleoredox conditions during the deposition of the Dolomite Member of the Ibex Formation using trace metal enrichments. The Dolomite Member shows enrichments of Ni, Mo, Fe, Cu, V, Co, and Ba near the base of the unit, and also has a weak overall enrichment in Mn. The enrichment of these metals suggests a period of anoxia during the initial deposition of the Dolomite, and may signal the introduction of basin brines to the shallow ocean during marine transgression. These data are consistent with patterns observed in other cap carbonates worldwide, and support the speculation that the Dolomite Member is a cap carbonate. Alternatively, trace metal enrichments may reflect diagenetic alteration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMPP31B1328V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMPP31B1328V"><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 ?18O change. Reconstructing changes in the ?18Owater of the global ocean assumes a homogeneous ?18O value for contributions from Northern hemisphere ice sheets with a mass balance contribution from the Southern hemisphere. Because oceanic ?18Ow 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 ?18Ow 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 ?18O (a temperature and ?18Owater proxy) on remaining shell material. O. universa has a very large temperature and salinity tolerance (9-30C; 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 (26.95N, 91.35W, 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 ?18O on 30-100 individual O. universa. The ?18O from each shell reflects the combined influence of temperature and ?18Owater, where this latter value is a function of mixing between seawater and ice sheet meltwater runoff. Mg/Ca data provide an independent reconstruction of temperature, and Ba/Ca is used as a proxy for salinity in the vicinity of riverine outflow. Combining these data permits us to compute both salinity and ?18Owater for each discrete foraminifera shell. We demonstrate that when an assemblage of salinity and ?18Owater paired data are combined, we are able to compute the ?18Owater of the freshwater (glacial) endmember.</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/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>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are powerful tracers of continental input, particle exchange and scavenging processes, as well as for water mass transport in the ocean. We present a first data set of dissolved REE distributions in filtered seawater covering the major gradients of bio-productivity and oxygen concentrations in the upwelling area off Peru. A total of 22 stations were analyzed along a shelf, a nearshore and an offshore transect to investigate the influence of local inputs versus water mass mixing. The Peruvian coastal upwelling area is a highly dynamic system characterized by intense upwelling of nutrient-rich subsurface water and therefore high productivity that leads to one of the globally largest Oxygen Minimum Zones (OMZ). The upwelling area off Peru is of particular interest for understanding the biogeochemical cycling of REEs and other redox-sensitive metals because anoxic conditions are expected to release of REEs from the shelf, whereas high particle densities and fluxes efficiently remove the REEs from the water column. Despite their high potential as tracers few systematic investigations of seawater REEs have been carried out so far because the low concentrations of REEs (pM) are difficult to measure. In this study an online preconcentration (OP) system (seaFast, <span class="hlt">Elemental</span> Scientific Inc.) was used with a technique slightly modified from Hathorne et al. (2012). The OP system efficiently separates seawater matrix <span class="hlt">elements</span> from the REEs and elutes the preconcentrated sample directly into the spray chamber of the ICP-MS instrument. Repeated measurements of a seawater reference sample (n= 20) during this study gave a reproducibility of between 5% and 15% (2?), with the worst reproducibility for Sm, Eu, and Gd (12% to 15%). In general, the REEs, except Ce, show a nutrient-like behavior in seawater increasing in concentration with water depth. However, such distributions were not observed for some stations on the shelf where the highest concentrations, 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 ?mol/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://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/abs/2014Litho.205..322K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Litho.205..322K"><span id="translatedtitle">Platinum-group <span class="hlt">element</span> (PGE) <span class="hlt">geochemistry</span> of Mesoarchean ultramafic-mafic cumulate rocks and chromitites from the Nuasahi Massif, Singhbhum Craton (India)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khatun, Sarifa; Mondal, Sisir K.; Zhou, Mei-Fu; Balaram, Vysetti; Prichard, Hazel M.</p> <p>2014-09-01</p> <p>The Mesoarchean Nuasahi Massif in eastern India comprises a lower ultramafic and an upper gabbro unit. The lower unit consists of orthopyroxenite, harzburgite, dunite and three chromitite bands. All of these rocks are characterized by adcumulate textures. The upper unit consists of gabbro with magnetite layers. At the contact between the eastern orthopyroxenite and the lower part of the upper gabbro, a sulfide-rich breccia zone with platinum-group-<span class="hlt">element</span> (PGE) mineralization is present. Detailed studies of major-, trace- and PGE abundances suggest that the ultramafic-mafic cumulate rocks, chromitites and breccias are genetically linked. The chondrite-normalized U-shaped rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns of the harzburgite resemble those of Phanerozoic boninite. The overall U-shaped REE patterns of the ultramafic rocks indicate derivation of the parental magma from a metasomatized depleted mantle source. The upper gabbros have higher relative abundances of trace <span class="hlt">elements</span> than the lower ultramafic rocks, due to crystallization from a fractionated magma. Whole-rock <span class="hlt">geochemistry</span> suggests that the lower ultramafic cumulate rocks with chromitites crystallized from a boninitic parental magma, whereas the upper gabbros with magnetite bands may be formed from residual boninitic magma that was contaminated by more tholeiitic-like magmas. The boninitic parental magma that crystallized to form the lower ultramafic unit was most likely generated by second-stage melting of a depleted metasomatized mantle source in a supra-subduction zone (SSZ) setting and emplaced into crustal sequences. The PGE abundances in the Nuasahi rocks provide additional constraints on their geochemical evolution during the Mesoarchean. Primitive-mantle-normalized PGE diagrams show (1) Ru enrichment in chromitites (Pd/Ru = 0.17-0.64), (2) Pd/Pt fractionation in both chromitites (Pd/Pt = 3.1) and ultramafic rocks (Pd/Pt = 0.62), (3) marked Ir depletion in ultramafic rocks (Pd/Ir = 6.3) and (4) overall PGE enrichment in chromitites (PGEtotal = 142-502 ppb). The large Ir depletion in the ultramafic rocks, and the overall Ir-depleted character of other rocks from the Nuasahi Massif, may be related to multiple episodes of melt extraction from the mantle source, giving it a subchondritic character.</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/2008JAESc..32..406C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JAESc..32..406C"><span id="translatedtitle">Platinum-group <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> of mafic and ultramafic rocks from the Xigaze ophiolite, southern Tibet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Genwen; Xia, Bin</p> <p>2008-04-01</p> <p>The Xigaze ophiolite in the central part of the Yarlung-Zangbo suture zone, southern Tibet, has a well-preserved sequence of sheeted dykes, basalts, cumulates and mantle peridotites at Jiding and Luqu. Both the basalts and diabases at Jiding have similar compositions with SiO 2 ranging from 45.9 to 53.5 wt%, MgO from 3.1 to 6.8 wt% and TiO 2 from 0.87 to 1.21 wt%. Their Mg #s [100Mg/(Mg + Fe)] range from 40 to 60, indicating crystallization from relatively evolved magmas. They have LREE-depleted, chondrite-normalized REE diagrams, suggesting a depleted mantle source. These basaltic rocks have slightly negative Nb- and Ti-anomalies, suggesting that the Xigaze ophiolite represents a fragment of mature MORB lithosphere modified in a suprasubduction zone environment. The mantle peridotites at Luqu are high depleted with low CaO (0.3-1.2 wt%) and Al 2O 3 (0.04-0.42 wt%). They display V-shaped, chondrite-normalized REE patterns with (La/Gd) N ratios ranging from 3.17 to 64.6 and (Gd/Yb) N from 0.02 to 0.20, features reflecting secondary metasomatism by melts derived from the underlying subducted slab. Thus, the <span class="hlt">geochemistry</span> of both the basaltic rocks and mantle peridotites suggests that the Xigaze ophiolite formed in a suprasubduction zone. Both the diabases and basalts have Pd/Ir ratios ranging from 7 to 77, similar to MORB. However, they have very low PGE abundances, closely approximating the predicted concentration in a silicate melt that has fully equilibrated with a fractionated immiscible sulfide melt, indicating that the rocks originated from magmas that were S-saturated before eruption. Moderate degrees of partial melting and early precipitation of PGE alloys explain their high Pd/Ir ratios and negative Pt-anomalies. The mantle peridotites contain variable amounts of Pd (5.99-13.5 ppb) and Pt (7.92-20.5 ppb), and have a relatively narrow range of Ir (3.47-5.01 ppb). In the mantle-normalized Ni, PGE, Au and Cu diagram, they are relatively rich in Pd and depleted in Cu. There is a positive correlation between CaO and Pd. The Pd enrichment is possibly due to secondary enrichment by metasomatism. Al 2O 3 and Hf do not correlate with Ir, but show positive variations with Pt, Pd and Au, indicating that some noble metals can be enriched by metasomatic fluids or melts carrying a little Al and Hf. We propose a model in which the low PGE contents and high Pd/Ir ratios of the basaltic rocks reflect precipitation of sulfides and moderate degrees of partial melting. The high Pd mantle peridotites of Xigaze ophiolites were formed by secondary metasomatism by a boninitic melt above a subduction zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V11A2509G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V11A2509G"><span id="translatedtitle">Deciphering tectonic provenance signatures from the trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of igneous zircon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grimes, C. B.; Wooden, J. L.; Vazquez, J. A.</p> <p>2011-12-01</p> <p>The ability to correlate stable isotope ratios and trace <span class="hlt">element</span> signatures with age on single crystals, coupled with resistance to chemical and physical weathering make zircon a useful complement in a wide range of geologic investigations. Zircon trace <span class="hlt">element</span> concentrations broadly reflect parental magma composition, although studies show that crystal chemistry also imparts a significant control on the shape of REE patterns. Concentrations of select <span class="hlt">elements</span> (e.g., Hf) and various trace <span class="hlt">element</span> ratios (e.g., Th/U, Yb/Gd, Eu/Eu*) commonly correlate with crystallization temperature (from Ti-in-zircon thermometry) for suites of zircon precipitated during magmatic fractionation in zircon-saturated systems. Other trace <span class="hlt">element</span> ratios, primarily U/Yb and Th/Yb plotted against Hf or Y discriminate zircon sampled in situ from mid-ocean ridges from those formed in arc-related ('continental') settings. However, these geochemical discriminations are limited in that ~20% of published mid-ocean ridge zircon compositions plot within the 'continental' zircon field and they fail to distinguish zircon from other magmatic settings such as ocean islands. To improve geochemical zircon discrimination diagrams for diverse tectonic environments, trace <span class="hlt">element</span> criteria that distinguish lavas from different tectonic settings are considered along with a broad suite of <span class="hlt">elements</span> routinely measured by the Stanford-USGS SHRIMP-RG ion probe. Arc-related magmas exhibit enrichment in large ion lithophile (LIL) <span class="hlt">elements</span> (i.e., U, Th) with respect to typical MORB, and are depleted in niobium (Nb) with respect to both OIB and MORB lavas. OIB lavas are typically enriched in LIL with respect to MORB, but lack the Nb-depletion characteristic of arcs. The ratios U/Yb, Yb/Nb, and Th/Nb can therefore be used to discriminate lavas from these different settings. Discrimination diagrams based on these <span class="hlt">elemental</span> ratios in zircon also define separate (though partly overlapping) fields for modern mid-ocean ridges, arcs, and the Hawaii hotspot. Based on existing datasets, juvenile island arc zircons (Izu-Bonin-Mariana) define a separate field from continental arc zircons from the Western US. Fields have been determined from over 1000 in situ analyses of zircon along with published compositions of zircon from the Izu-Bonin-Mariana arc system (Tani et al., 2010, Geology 38:215-218). These new trace <span class="hlt">element</span> discrimination diagrams can complement geochronologic studies of detrital, xenocrystic, or other ancient zircon populations with an uncertain igneous provenance. In primitive basalts, Nb/Yb ratio is considered an indicator of mantle fertility, whereas LIL/Nb ratios are heavily influenced by slab-derived fluids from subduction. Although co-crystallizing minerals in evolved, zircon-saturated melts will impact trace <span class="hlt">element</span> ratios, to a first-order we suggest these signatures extend to zircon populations as well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/194767','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/194767"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> in water from selected springs in Death Valley National Park, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kreamer, D.K.; Hodge, V.F.; Rabinowitz, I.; Johannesson, K.H.; Stetzenbach, K.J.</p> <p>1996-01-01</p> <p>Concentrations of 40 trace <span class="hlt">elements</span> and other constituents in ground water from springs in Death Valley National Park were measured to investigate whether trace <span class="hlt">element</span> composition of the ground water can be related to the aquifer materials. Samples from these springs were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) for the trace <span class="hlt">elements</span> and by ion chromatography (IC) for the major anions. A Principal Component Analysis was performed on the data set. Surprise and Scotty`s Springs formed one group; Texas, Nevares, and Travertine Springs formed another group; and Mesquite Springs did not group with any of the others. Scotty`s and Surprise Spring issued from volcanic rocks; Texas, Nevares, and Travertine discharge from carbonate rocks; and Mesquite Spring is located in alluvial basin-fill deposits. The first three components in each principal Component Analysis accounted for approximately 95% of the variance in the data set. The Principal Component Analysis suggests that ground water inherits its trace <span class="hlt">element</span> composition from the rocks or aquifer material with which it has interacted and may be used for the purpose of identifying ground-water movement and source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7084C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7084C"><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, establishing a company in China can lower the production cost (since the company buys the products used in its production at a lower price). In the fifth session, they study the raw materials trading based on the futures contracts example. A producer, to avoid a rise in prices of raw materials used in his production can use derivative products on the financial market: futures contracts for instance. This product ensures a quantity and quality for a price and a delivery date agreed upon today. Actually, producers can use a method called Fix price hedging in order to fix the price of a specific product. The main idea is to balance out the "physical position" (spot market) and the "paper position" (futures market). Even if the REE are commercialized in form of a non-perishable's oxide, the flow of the stock must be guaranteed and this is why it is important for producers to secure their supply of raw materials. In the last session, students search local companies that use REE in their production process and study their strategy on the market.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.B31D0621H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.B31D0621H"><span id="translatedtitle">Major <span class="hlt">Element</span> <span class="hlt">Geochemistry</span> of Biofilms in a Silica-Precipitating Hot Spring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Havig, J. R.; Shock, E. L.; Moore, G.</p> <p>2007-12-01</p> <p>Hydrothermal biofilm communities represent one of the best present-day representations of early microbial communities, dating back to 2.5 Ga, and possibly 3.8 Ga in the geologic record. Silica-precipitating hydrothermal springs have been thought to have great potential for biosignature preservation. The interactions of hydrothermal water, biofilms, and precipitated siliceous sinter, however, remain poorly constrained. To this end, we collected water and biofilm, as well as contextual sinter and rock samples from various hot springs in Yellowstone National Park. Here we focus on one hot spring in Sentinel Meadow (Lower Geyser Basin), with temperature and pH that vary from the source (93 C, pH 7.4) to the farthest of five collection points down channel (56 C, pH 8.2). <span class="hlt">Elemental</span> analysis reveals that the biofilms are made up of from <1 to ~11 % dry wt. carbon and ~0.1 to 1% dry wt. nitrogen. Major <span class="hlt">element</span> analysis via electron microprobe and complimentary x-ray fluorescence show that (excluding C and N from the total) SiO2 constitutes 86 to 94 % dry weight mass, with the rest made up of Al2O3 (3 to 8%), Na2O (1.7 to 3.7%), K2O (0.6 to 1.5%), and minor amounts of FeO, CaO, MgO, and TiO2 (<1%). Local sinter is SiO2 (97.5% dry wt.), Na2O (1.5%), and <1% Al2O3, FeO, K2O, CaO, MgO, and TiO2. In addition, sinter contains measurable amounts of carbon (1.4%) and nitrogen (0.2%). Discrepancies between the biofilm and sinter values show that the geochemical compositions of biofilms are not captured by the precipitating silica. If biofilms accumulated <span class="hlt">elements</span> strictly from the water, then it would take as much as 440 L of water to supply 1 gram (dry wt) of biofilm with the <span class="hlt">elements</span> contained therein, assuming complete uptake. This seems especially unlikely in the case of Al, which is quite dilute (~500 ppb), poses very little benefit nutritionally, and increases in concentration down channel. Other major <span class="hlt">element</span> components also exhibit at least one, if not all, of these traits. A potential source of the <span class="hlt">elements</span> found in biofilms is aeolian-deposited dust. Area country rock is dominated by siliceous volcanism, represented locally by rhyolite samples collected from Sentinel Meadow. With an average value of ~10 wt % Al2O3 for the surrounding country rock, it would take approximately 0.6 grams of the ground up rock as dust to account for the Al found in one gram of biofilm. The low Al2O3 content of the sinter indicates that the Al is not entombed from the biofilms. A hypothesis for the above discrepancies in Al (as well as other <span class="hlt">elements</span>) is that dust deposited in the water is captured on the biofilm surfaces, and the biofilm community then breaks down the dust, utilizing any nutritionally or metabolically important <span class="hlt">elements</span>, and either precipitating (for Si) or releasing (for Al) unnecessary <span class="hlt">elements</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.8541B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.8541B"><span id="translatedtitle">Targeting heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> in carbonatite complexes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Broom-Fendley, S.; Wall, F.; Gunn, A. G.; Dowman, E.</p> <p>2012-04-01</p> <p>The world's main sources of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are concentrated in carbonatite complexes. These have the advantages of high grade and tonnage, combined with low thorium contents, yet they are generally enriched in light rare <span class="hlt">earths</span> (LREE). The heavy rare <span class="hlt">earths</span> (HREE, which include Eu-Lu and Y) are more highly sought after because of their role in new and green technologies. HREE are predominantly extracted from ion-adsorption clays in China. These are small, low grade deposits, which are often illegally mined by artisans. Increased government control, environmental legislation and local demand for REE in China have led to high prices and global concerns about the security of supply of the HREE. Alternative sources of the HREE are poorly documented. We present a review of such targets, including: (1) 'abnormal' carbonatites; (2) areas around LREE-rich complexes such as breccia, fenite and latter stage veins; and (3) weathered carbonatites. At Lofdal, Namibia, carbonatite dykes contain xenotime-(Y) together with LREE minerals. The original chemistry of the carbonatite magma, coupled with late-stage magma and fluid evolution, seem to be controlling factors [1, 2]. The Khibina carbonatite, Kola Peninsula, Russia, is an example of where early LREE carbonatites become increasing HREE-enriched as magmas evolve to carbo-hydrothermal fluids [3]. Around carbonatite complexes in Malawi HREE enrichment can be found in breccia and in fenite. Breccia around Songwe shows areas with high Y/La ratios within the matrix caused by narrow zones of xenotime enrichment. Fenite around Kangankunde and Chilwa Island has higher HREE:LREE ratios than the carbonatite [4]. At weathered complexes, such as at Mount Weld in Western Australia, changes in both HREE concentration and LREE:HREE ratios are observed. In currently unworked sections of the deposit, the HREE mineral churchite (YPO4.H2O) has formed concentrations due to groundwater flow [5]. These areas of enrichment are reviewed in terms of their grade, tonnage, rock type and the potential environmental impacts associated with their exploitation. [1] Wall et al. (2008), Can Mineral, 46, 861. [2] Do Cabo et al. (2011), Minmag, 75 (3), 770. [3] Zaitsev et al. (1998), Minmag, 62 (2), 225. [4] Dowman et al. (2011), abstract, Fermor conference, London. [5] Lottermoser (1990), Lithos, 24, 151</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.7134D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.7134D"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> as a fingerprint of soil components solubilization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davranche, M.; Grybos, M.; Gruau, G.; Pdrot, M.; Dia, A.</p> <p>2009-04-01</p> <p>The retention of rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) in the soil profile are mainly controlled by three factors, (i) the stability of the primary REE-carrying minerals, (ii) the presence of secondary phases as clays and Fe- and Mn-oxyhydroxides and (ii) the concentration of colloidal organic matter (OM). Considering that each soil phases (mineral or organic) displays (ii) various surface properties, such as specific area, surface sites density and nature and (ii) their own REE distribution inherited from the rock weathering, their mobilization through various chemical reactions (dissolution, colloidal release.) may involve the development of various shaped REE patterns in the soil solutions. REE fractionation from the different soil phases may therefore be used to identify the response of the soil system to a particular chemical process such as reductive and/or acidic dissolution. To test this purpose, an organic-rich wetland soil sample was incubated under anaerobic condition at both pH 5 and uncontrolled pH. The REE patterns developed in the soil solution were then compared to the REE patterns obtained through either aerobic at pH 3 and 7 incubations or a chemical reduction experiment (using hydroxylamine). REE patterns in anaerobic and aerobic at pH 7 experiments exhibited the same middle rare <span class="hlt">earth</span> <span class="hlt">element</span> (MREE) downward concavity significant of the complexation of REE with soil OM. By contrast, under acidic condition, the REE pattern exhibited a positive Eu anomaly due to the dissolution of soil feldspar. Finally, REE pattern obtained from the chemical reducing experiment showed an intermediary flat shape corresponding to a mixing between the soil organic and mineral phases dissolution. The comparison of the various REE pattern shapes allowed to conclude that (i) biological reduction of wetland soil involved amorphous Fe(III) colloids linked to OM and, (ii) that the REE mobility was controlled by the dynamic of OM in wetland soil. They also evidence the potential of REE to be use as a tracer of the soil phases involved in the various chemical processes running in soil solutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.B21C0371R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.B21C0371R"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in scleractinian cold-water corals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raddatz, J.; Liebetrau, V.; Hathorne, E. C.; Rüggeberg, A.; Dullo, W.; Frank, M.</p> <p>2012-12-01</p> <p>The Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) have a great potential to trace continental input, particle scavenging and the oxidation state of seawater. These REE are recorded in the skeleton of the cosmopolitan cold-water corals Lophelia pertusa. Here we use an online preconcentration ICP-MS method (Hathorne et al. 2012) to measure REE concentrations in seawater and associated cold-water coral carbonates in order to investigate their seawater origin. Scleractinian cold-water corals were collected in-situ and alive and with corresponding seawater samples covering from the European Continental Margin. The seawater REE patterns are characterized by the typical negative cerium anomaly of seawater, but are distinct for the northern Norwegian Margin and the Oslo Fjord, probably related to continental input. Initial results for the corresponding coral samples suggest that these distinct REE patterns of ambient seawater are recorded by the coral skeletons although some fractionation during incorporation into the aragonite occurs. This indicates that scleractinian cold-water corals can serve as a valuable archive for seawater derived REE signatures, as well radiogenic Nd isotope compositions. In a second step we analysed fossil coral samples from various locations, which were oxidatively and reductively cleaned prior to analysis. Initial results reveal that sediment-buried fossil (early Pleistocene to Holocene) coral samples from the Norwegian Margin and the Porcupine Seabight (Challenger Mound, IODP Site 1317) do not show the expected seawater REE patterns. In particular, the fossil coral-derived REE patterns lack a negative cerium anomaly suggesting that fossil coral-REE patterns do not represent ambient seawater. Thus, we suggest that the oxidative-reductive cleaning method widely used for cleaning of marine carbonates such as foraminifera prior to measurements of seawater-derived trace metal and isotope compositions are not sufficient for REE and Nd isotopes in sediment-buried coral-water corals and require alternative or additional approaches. Hathorne, E.C., B. Haley, T. Stichel, P. Grasse, M. Zieringer, and M. Frank (2012). Online preconcentration ICP-MS analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in seawater, Geochem. Geophys. Geosyst.,13, Q01020, doi:10.1029/2011GC003907. .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997CoMP..129..284C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997CoMP..129..284C"><span id="translatedtitle">Metasomatism in the subcontinental mantle beneath the Eastern Carpathians (Romania): new evidence from 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>Chalot-Prat, Franoise; Boullier, Anne-Marie</p> <p></p> <p>A wide range of trace <span class="hlt">elements</span> have been analysed in mantle xenoliths (whole rocks, clinopyroxene and amphibole separates) from alkaline lavas in the Eastern Carpathians (Romania), in order to understand the process of metasomatism in the subcontinental mantle of the Carpatho-Pannonian region. The xenoliths include spinel lherzolites, harzburgites and websterites, clinopyroxenites, amphibole veins and amphibole clinopyroxenites. Textures vary from porphyroclastic to granoblastic, or equigranular. Grain size increases with increasing equilibrium temperature of mineralogical assemblages and results from grain boundary migration. In peridotites, interstitial clinopyroxenes (cpx) and amphiboles resulted from impregnation and metasomatism of harzburgites or cpx-poor lherzolites by small quantities of a melt I with a melilitite composition. Clinopyroxenites, amphibole veins and amphibole clinopyroxenites are also formed by metasomatism as a result of percolation through fracture systems of large quantities of a melt II with a melanephelinite composition. These metasomatic events are marked by whole-rock enrichments, relative to the primitive mantle (PM), in Rb, Th and U associated in some granoblastic lherzolites and in clinopyroxene and amphibole veins with enrichments in LREE, Ta and Nb. Correlations between major <span class="hlt">element</span> whole-rock contents in peridotites demonstrate that the formation of interstitial amphibole and clinopyroxene induced only a slight but variable increase of the Ca/Al ratio without apparent modifications of the initial mantle composition. Metasomatism is also traced by enrichments in the most incompatible <span class="hlt">elements</span> and the LREE. The Ta, Nb, MREE and HREE contents remained unchanged and confirm the depleted state of the initial but heterogeneous mantle. Major and trace <span class="hlt">element</span> signature of clinopyroxene suggests that amphibole clinopyroxenites and some granoblastic lherzolites have been metasomatized successively by melts I and II. Both melts I and II were Ca-rich and Si-poor, somewhat alkaline (Na>K). Melt I differed from melt II in having higher Mg and Cr contents offset by lower Ti, Al, Fe and K contents. Both were highly enriched in all incompatible trace <span class="hlt">elements</span> relative to primitive mantle, showing positive anomalies in Rb, Ba, Th, Sr and Zr. They contrasted by their Ta, Nb and LREE contents, lower in melt I than in melt II. Melts I and II originate during a two-stage melting event from the same source at high pressure and under increasing temperature. The source assemblage could be that of a metasomatized carbonated mantle but was more likely that of an eclogite of crustal affinity. Genetic relationships between calc-alkaline and alkaline lavas from Eastern Carpathians and these melts are thought to be only indirect, the former originating from partial melting of mantle sources respectively metasomatized by the melts I and II.</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://adsabs.harvard.edu/abs/2014MinDe..49.1013H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MinDe..49.1013H"><span id="translatedtitle">Geochemical prospecting for rare <span class="hlt">earth</span> <span class="hlt">elements</span> using termite mound materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Horiuchi, Yu; Ohno, Tetsuji; Hoshino, Mihoko; Shin, Ki-Cheol; Murakami, Hiroyasu; Tsunematsu, Maiko; Watanabe, Yasushi</p> <p>2014-12-01</p> <p>The Blockspruit fluorite prospect, located in North West State of the Republic of South Africa, occurs within an actinolite rock zone that was emplaced into the Kenkelbos-type granite of Proterozoic age. There are a large number of termite mounds in the prospect. For geochemical prospecting for rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), in total, 200 samples of termite mound material were collected from actinolite rock and granite zones in the prospect. Geochemical analyses of these termite mound materials were conducted by two methods: portable X-ray fluorescence (XRF) spectrometry and inductively coupled plasma-mass spectrometry (ICP-MS). Comparison of the two methods broadly indicates positive correlations of REEs (La, Ce, Pr, Nd, and Y), in particular Y and La having a strong correlation. As the result of modal abundance analyses, the actinolite rock at surface mainly consists of ferro-actinolite (89.89 wt%) and includes xenotime (0.26 wt%) and monazite (0.21 wt%) grains as REE minerals. Termite mound materials from actinolite rock also contain xenotime (0.27 wt%) and monazite (0.41 wt%) grains. In addition, termite mound materials from the actinolite rock zone have high hematite and Fe silicate contents compared to those from granite zone. These relationships suggest that REE minerals in termite mound materials originate form actinolite rock. Geochemical anomaly maps of Y, La, and Fe concentrations drawn based on the result of the portable XRF analyses show that high concentrations of these <span class="hlt">elements</span> trend from SW to NE which broadly correspond to occurrences of actinolite body. These results indicate that termite mounds are an effective tool for REE geochemical prospection in the study area for both light REEs and Y, but a more detailed survey is required to establish the distribution of the actinolite rock body.</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://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/2014EGUGA..16.5328M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5328M"><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 <span class="hlt">elements</span> such as Ca, Mg, Sr or U are relatively high in whitewater rivers, their concentrations are generally lower in clearwater rivers and lowest in blackwater rivers. In contrast, <span class="hlt">elements</span> including Si, Rb and Cs have their highest concentrations in blackwater rivers, intermediate concentrations in clearwater rivers and their lowest concentrations in whitewater river. [1] Elderfield H., Upstill-Goddard R. and Sholkovitz E.R. (1990): The rare <span class="hlt">earth</span> <span class="hlt">elements</span> in rivers, estuaries and coastal seas and their significance to the composition of ocean waters. Geochim.Cosmochim.Acta, 54, 971-991 [2] Gerard M., Seyler P., Benedetti M.F., Alves V.P., Boaventura G.R. and Sondag, F. (2003): Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Amazon basin. Hydrological Processes, 17, 1379-1392 [3] Molinier M., Guyot J.L., Callede J., Guimaraes V., Oliveira E. and Filizola N. (1997): Hydrologie du bassinamazonien. Evironment et développement en Amazonie brésiliènne, Thery H. (ed.), Berlin Publ., Paris; 24-41</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000GPC....26..217S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000GPC....26..217S"><span id="translatedtitle">Processes controlling trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of Arabian Sea sediments during the last 25,000 years</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sirocko, Frank; Garbe-Schnberg, Dieter; Devey, Colin</p> <p>2000-11-01</p> <p>Thirty seven deep-sea sediment cores from the Arabian Sea were studied geochemically (49 major and trace <span class="hlt">elements</span>) for four time slices during the Holocene and the last glacial, and in one high sedimentation rate core (century scale resolution) to detect tracers of past variations in the intensity of the atmospheric monsoon circulation and its hydrographic expression in the ocean surface. This geochemical multi-tracer approach, coupled with additional information on the grain size composition of the clastic fraction, the bulk carbonate and biogenic opal contents makes it possible to characterize the sedimentological regime in detail. Sediments characterized by a specific <span class="hlt">elemental</span> composition (enrichment) originated from the following sources: river suspensions from the Tapti and Narbada, draining the Indian Deccan traps (Ti, Sr); Indus sediments and dust from Rajasthan and Pakistan (Rb, Cs); dust from Iran and the Persian Gulf (Al, Cr); dust from central Arabia (Mg); dust from East Africa and the Red Sea (Zr/Hf, Ti/Al). C org, Cd, Zn, Ba, Pb, U, and the HREE are associated with the intensity of upwelling in the western Arabian Sea, but only those patterns that are consistently reproduced by all of these <span class="hlt">elements</span> can be directly linked with the intensity of the southwest monsoon. Relying on information from a single <span class="hlt">element</span> can be misleading, as each <span class="hlt">element</span> is affected by various other processes than upwelling intensity and nutrient content of surface water alone. The application of the geochemical multi-tracer approach indicates that the intensity of the southwest monsoon was low during the LGM, declined to a minimum from 15,000-13,000 14C year BP, intensified slightly at the end of this interval, was almost stable during the Blling, Allerd and the Younger Dryas, but then intensified in two abrupt successions at the end of the Younger Dryas (9900 14C year BP) and especially in a second event during the early Holocene (8800 14C year BP). Dust discharge by northwesterly winds from Arabia exhibited a similar evolution, but followed an opposite course: high during the LGM with two primary sourcesthe central Arabian desert and the dry Persian Gulf region. Dust discharge from both regions reached a pronounced maximum at 15,000-13,000 14C year. At the end of this interval, however, the dust plumes from the Persian Gulf area ceased dramatically, whereas dust discharge from central Arabia decreased only slightly. Dust discharge from East Africa and the Red Sea increased synchronously with the two major events of southwest monsoon intensification as recorded in the nutrient content of surface waters. In addition to the tracers of past dust flux and surface water nutrient content, the geochemical multi-tracer approach provides information on the history of deep sea ventilation (Mo, S), which was much lower during the last glacial maximum than during the Holocene. The multi-tracer approachi.e. a few sedimentological parameters plus a set of geochemical tracers widely available from various multi-<span class="hlt">element</span> analysis techniquesis a highly applicable technique for studying the complex sedimentation patterns of an ocean basin, and, specifically in the case of the Arabian Sea, can even reveal the seasonal structure of climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CorRe..31..671M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CorRe..31..671M"><span id="translatedtitle">Potassium and other minor <span class="hlt">elements</span> in Porites corals: implications for skeletal <span class="hlt">geochemistry</span> and paleoenvironmental reconstruction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitsuguchi, T.; Kawakami, T.</p> <p>2012-09-01</p> <p>We investigated how the K/Ca, Na/Ca, Mg/Ca, and Sr/Ca ratios of powders ground from Porites coral skeletons are changed by cumulative chemical treatments to the powders: first with distilled/deionized water (DDW), next with 30 % H2O2 and then with 0.004 mol l-1 HNO3. The K/Ca, Na/Ca, and Mg/Ca ratios were decreased with the DDW treatment and then increased with the H2O2 and HNO3 treatments; the Sr/Ca ratio was slightly decreased through the cumulative treatments, suggesting fine-scale (tens of μm or less) <span class="hlt">elemental</span> heterogeneities in the skeleton—K, Na, and Mg are significantly enriched at the skeletal surface and also at the center of calcification (COC); in contrast, the heterogeneity of Sr is very small. We suggest that the principal mechanisms of K incorporation into coral skeleton are (1) ion incorporation into lattice defects/distortions and (2) ion adsorption onto crystal discontinuities (including crystal-organic matter interfaces) as forms of K+ and KSO4 -. Furthermore, we measured the <span class="hlt">element</span>/Ca ratios of a modern Porites coral skeleton along its growth direction at 2-mm intervals. Results showed that all the <span class="hlt">element</span>/Ca ratios displayed annual cycles, that the K/Ca and Na/Ca ratios covaried with each other, and that the annual-minimum K/Ca and Na/Ca ratios coincided with the annual high-density band in the skeleton. It is unclear what environmental factors may cause the covarying annual cycles of the K/Ca and Na/Ca ratios; however, as a possible explanation, the cycles may be due not to environmental factors, but to a combined effect of (1) the K and Na enrichment at the COC, (2) annual bands of high- and low-density skeleton, and (3) mm-scale <span class="hlt">element</span>/Ca measurements along the skeletal growth direction. This kind of effect on geochemical proxies of which the concentrations significantly differ between the COC and surrounding skeleton may generate false or distorted paleoenvironmental signals.</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/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://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> <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/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/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://www.ncbi.nlm.nih.gov/pubmed/11302578','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11302578"><span id="translatedtitle">Uptake and distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in rice seeds cultured in fertilizer solution of rare <span class="hlt">earth</span> <span class="hlt">elements</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yuan, D; Shan, X; Huai, Q; Wen, B; Zhu, X</p> <p>2001-04-01</p> <p>The uptake behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) under pot conditions using deionized water and a REE fertilizer solution as the culture media as well as the distribution of REEs in rice proteins were studied. The uptake of REEs in rice seeds increased dramatically after a lag period of approximately three days. Roots can accumulate a much higher content of REEs than germs and the resting seeds. The REE content in each water-soluble (albumin) and salt-soluble (globulin) component of the rice seeds accounted for 5-8% and 4-6% of the total REEs, respectively. However, there are less than 1.5% of the total REEs were found in the alcohol-soluble (prolamin) and acetic acid-soluble (glutelin) components. The high performance liquid chromatography (HPLC) in the gel permeation and the reserved-phase were used to monitor changes in the molecular weight distribution changes of the soluble proteins of rice seeds during germination after having been cultured in the same solution for seven days. No changes occurred in the prolamin, while a slight change occurred in the albumin, globulin and glutelin. Fractionation of the albumin of rice seeds cultured in a REE fertilizer solution on the Sephadex G-100 column indicated that REEs, especially Ce, La, Pr and Nd, were associated mainly with biological compounds of a molecular weight between 10,000 and 12,000. PMID:11302578</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. 730-870C). Their ?18O 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 +131 ?-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 ?18O values (down to -6 ). We interpret these to reflect multiple episodes of partial melting and melt extraction of the same unit. In-situ (SHRIMP) dating of zircons yields a pooled age of 6.430.04 Ma for the MFCZ. However, a relatively high MSWD (1.6) suggests real spread in ages ranging from ~6.3 to 6.6 Ma, corroborating field evidence for the construction of the MFCZ by repeated mafic and felsic intrusions and periodic re-melting and rejuvenation of mush-like material within the complex, over a ~250 k.y. span.</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/1984smeg.rept.....C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984smeg.rept.....C"><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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clynne, M. A.</p> <p></p> <p>Detailed geologic mapping of 200 sq km 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 Volcanic 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. Stages 1 and 2 produced Brokeoff Volcano, 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 3 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 andesite and dacite with high Al2O3, low TiO2, medium K2O, and FeO/MgO 1.5 to 2.0 are the most abundant rock types.</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 conclusions on the impact of depositional setting and diagenetic remobilization and authigenic mineral formation on the REE system in the Marcellus Shale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/324600','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/324600"><span id="translatedtitle">Coal-forming environments and <span class="hlt">geochemistry</span> of minor and trace <span class="hlt">elements</span> of Cretaceous coals in Pingzhuang Basin, Inner Mongolia, China</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shao, J.; Wang, Y.; Gao, C.</p> <p>1997-12-31</p> <p>Pingzhuang Basin is a semi-grabenal fault basin of early Mesozoic age in China. Yuanbaoshan Formation of Lower Cretaceous is the main coal measure of the basin. The thickness of coal seams and the number of coal seams in each mining area vary through out the basin. The main coal-forming environments of the basin are lacustrine, lake-margin-fan-delta, lake-margin-delta, alluvial fan and fluvial faces. The coal-forming environment of different mining areas and seams in the basin varies. Ershijiazi Mining Area, which is located in the northeastern part of the basin, is mainly forefan-marsh and lakeside coal-formation; Silongtougou Mining Area, which is located in the southwestern part of the basin, is mainly lake-margin-delta coal-formation; Gushan Mining Area and West Open Pit Mining Area, which is located in the center of the basin, are mainly lakeside, lake-margin-delta-plain, lake-margin-fan-delta coal-formation. The distribution of <span class="hlt">element</span> contents of coals in different mining areas and seams differs. At Silongtougou, the contents of most minor and trace <span class="hlt">elements</span> are low except strontium. At Ershijiazi, the contents of some <span class="hlt">elements</span>, such as Fe, Co, Ni, As, Sb, Sc, Cs and U, are high in the basin, and the contents of Ba, Sr and Hf are low. At West Open Pit, the contents of most <span class="hlt">elements</span>, such as Fe, Zn, Co, Ni, As, Sb, K, Sc, Cs, Zr, U and Hf, are stable in the different seams, and the contents of these <span class="hlt">elements</span> are intermediate in the basin. The contents of other <span class="hlt">elements</span> in the area are low. At Gushan, the contents of all <span class="hlt">elements</span> in seam 5 are low, and in seam 6 are high. The <span class="hlt">elements</span> similar in geochemical characteristics have good correlation. The main correlated <span class="hlt">elements</span> are due to the formations of the organic molecular structures of coals and/or the formations of inorganic minerals in coals. The rare-<span class="hlt">earth-element</span> (REE) contents of coals in different mining areas and seams also differ, but the REE distribution patterns of all coals are alike. This indicates that the coal-forming conditions of the basin are stable. There is a good relationship between the contents of minor and trace <span class="hlt">elements</span> and the coal-forming environments.</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 isotopes that sulfate was not originated from oxidation process of pyrite. A weak correlation was observed between δ34SSO4 values and total As contents when all the samples were considered. Although, there is evidence for sulfate reduction, however; it is less clear about co-pricipitation or sequester of As with Fe and Sulfide ion. It is evident that As distribution in subsurface geological media is not controlled by single solid phase. Probably, dissolution-desorption from different phases contributes to the total As in groundwater. The data are consistant with the possibility that microbial mediated reactions and reductive dessolution of Fe-oxyhydroxides are the important processes to mobilize arsenic in this area. The combination of slow flow of groundwater and the younger age of aquifer sediments are also considered potentially important causes for the high dissolved As concentrations in groundwater as the sediments have not been well flushed since burial.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V23A2765E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V23A2765E"><span id="translatedtitle">Major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of ilmenite suites from the Kimberley diamond mines, 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>Ene, V. V.; Schulze, D. J.</p> <p>2013-12-01</p> <p>We have undertaken an electron microprobe and LA-ICP-MS study of ilmenites from Kimberley, South Africa, to understand better the mantle sources of ilmenite xenocrysts, key indicator minerals in kimberlite exploration. Among mantle xenoliths from Kimberley mines, ilmenite occurs in the following rock types: MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside), Granny Smith glimmerites (cpx-phlogopite-ilmenite), rutile -ilmenite rocks, dunites (olivine-ilmenite) and phlogopite orthopyroxenites. Using major, minor and trace <span class="hlt">elements</span> we have created a preliminary classification scheme for Kimberley ilmenites. Our data allow distinction between four broad suites: MARID, Granny Smith/rutile, orthopyroxenites and dunites. MARID ilmenites are generally the lowest in MgO (5.3-15.21 wt %) and Al2O3 (<0.05 wt %) and highest in Fe2O3 (6.6-23.4 wt %) and those from the Granny Smith/rutile suite have high MgO contents in the narrow range (13.0-14.9 wt %), with Al2O3 in the range 0.2-0.6 wt% and low Fe2O3 (4.9-6.7 wt %) values. Ilmenites from orthopyroxenites mostly have intermediate MgO, Al2O3 and Fe2O3 contents (10.8 -13.5 wt%, 0.1-0.4 wt % and 9.8-10.4 wt%, respectively). Ilmenites from dunites range to high MgO and Cr2O3 values (5.01-15.49wt % and 0.07-6.5 wt % respectively). The range of Nb2O5 contents of the Granny Smith/rutile ilmenites is very restricted (0.07-0.14 wt %) whereas those of MARID, orthopyroxenites and dunites are in a much wider range (0.03-1.74 wt% Nb2O5). Ilmenites belonging to the dunite suite cluster in three different groups, based on their Mg, Cr and Nb contents. One of these groups has MgO and Cr2O3 values similar to those of the rutile and Granny Smith suites, while the other have lower MgO contents. The three suites can be somewhat distinguished on the basis of comparison of MgO vs. Cr2O3, Al2O3 vs. Nb2O5, FeO vs. Fe2O3 (calculated from stoichiometry) and Cu/W vs Co/Cu. Distinguishing between the rutile, Granny Smith and part of the dunite suite is extremely difficult due to extensive compositional overlap, suggesting that they have a common genesis perhaps forming in related metasomatic events. Trace <span class="hlt">element</span> data are consistent with such a hypothesis. All three suites have V values in the 900 - 1200 ppm range, Zr contents that range from 300 to 550 ppm and similar Sn values (6.69 - 9.07 ppm). We have applied these preliminary distinctions to ilmenite xenocrysts fom the Wesselton, Bultfontein, Kampfersdam and Otto's Kopje Mines in Kimberley. For example, we infer that >75% of the ilmenites from Wesselton and Kampfersdam belong to the rutile/dunite/Granny Smith suite compared to Otto's Kopje where the majority belongs to the MARID, orthopyroxenite and dunite suites. Ilmenites from all suites are present in approximately equal proportions at Bultfontein.</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://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 affinity for Ba which is many orders of magnitude greater than iron (hydr)oxides. Hence, the downcore distribution of Ba in Fe (hydr)oxide rich sediments is most probably controlled by the presence of Mn (hydr)oxides. U is enriched in the upper zones of the cores, consistent with the formation of highly reducing near-surface sediments in the intertidal zone at the head of the Bay. Hence, the recirculation of seawater through this type of subterranean estuary, coupled with the abiotic and/or biotic reduction of soluble U(VI) to insoluble U(IV), leads to the sediments acting as a oceanic net sink of U. These results highlight the importance of permeable sediments as hosts to a wide range of biogeochemical reactions, which may be impacting geochemical budgets on scales ranging from coastal aquifers to the continental shelf.</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://ntrs.nasa.gov/search.jsp?R=19820036624&hterms=rare+earth+elements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Drare%2Bearth%2Belements','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820036624&hterms=rare+earth+elements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Drare%2Bearth%2Belements"><span id="translatedtitle">Mineralogy, petrology, and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Johnstown meteorite - A brecciated orthopyroxenite with siderophile and REE-rich components</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Floran, R. J.; Prinz, M.; Hlava, P. F.; Keil, K.; Spettel, B.; Waenke, H.</p> <p>1981-01-01</p> <p>The compositional and petrologic characteristics of the Johnstown meteorite show it to contain uncontaminated and unbrecciated orthopyroxenite clasts of cumulative origin that (1) must have undergone subsolidus recrystalization, (2) are parental to the brecciated matrix, and (3) show no evidence of a xenolithic, meteoritic contribution to the matrix except for contamination by the projectile which crushed it on impact. The trapped liquid was not introduced in the impact process. The variability of such trace <span class="hlt">elements</span> as the light rare <span class="hlt">earth</span> <span class="hlt">elements</span>, and the presence of plagioclase and olivine in only one of the thin sections studied, demonstrates the heterogeneity of coarse-grained diogenites on a millimeter scale and the difficulty of obtaining representative samples of such meteorites. The data presented indicate that this meteorite is a monominct breccia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004GeCoA..68.1361P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004GeCoA..68.1361P"><span id="translatedtitle">Platinum group <span class="hlt">element</span> <span class="hlt">geochemistry</span> of komatiites from the Alexo and Pyke Hill areas, Ontario, Canada</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; Campbell, Andrew J.; Sproule, Rebecca A.; Lesher, C. Michael</p> <p>2004-03-01</p> <p>Thirty-three whole-rock drill core samples and thirteen olivine, chromite, and sulfide separates from three differentiated komatiite lava flows at Alexo and Pyke Hill, Canada, were analyzed for PGEs using the Carius tube digestion ID-ICP-MS technique. The emplaced lavas are Al-undepleted komatiites with 27% MgO derived by 50% partial melting of LILE-depleted Archean mantle. Major and minor <span class="hlt">element</span> variations during and after emplacement were controlled by 30 to 50% fractionation of olivine Fo 93-94. The emplaced lavas are characterized by (Pd/Ir) N = 4.0 to 4.6, (Os/Ir) N = 1.07, and Os abundances of 2.3 ppb. Variations in PGE abundances within individual flows indicate that Os and Ir were compatible (bulk DOs,Ir = 2.4-7.1) and that Pt and Pd were incompatible (bulk DPt,Pd < 0.2) during lava differentiation, whereas bulk DRu was close to unity. Analyses of cumulus olivine separates indicate that PGEs were incompatible in olivine ( DPGEsOl-Liq = 0.04-0.7). The bulk fractionation trends cannot be accounted for by fractionation of olivine alone, and require an unidentified Os-Ir-rich phase. The composition of the mantle source (Os = 3.9 ppb, Ir = 3.6 ppb, Ru = 5.4 ppb, Pt and Pd = 5.7 ppb) was constrained empirically for Ru, Pt, and Pd; the Os/Ir ratio was taken to be identical to that in the emplaced melt, and the Ru/Ir ratio was taken to be chondritic, so that the absolute IPGE abundances of the source were determined by Ru. This is the first estimate of the PGE composition of a mantle source derived from analyses of erupted lavas. The suprachondritic Pd/Ir and Os/Ir of the inferred Abitibi komatiite mantle source are similar to those in off-craton spinel lherzolites, orogenic massif lherzolites, and enstatite chondrites, and are considered to be an intrinsic mantle feature. Bulk partition coefficients for use in komatiite melting models derived from the source and emplaced melt compositions are: DOs,Ir = 2.3, DRu = 1.0, DPt,Pd = 0.07. Ruthenium abundances are good indicators of absolute IPGE abundances in the mantle sources of komatiite melts with 26 to 29% MgO, as Ru fractionates very little during both high degrees of partial melting and lava differentiation.</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://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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020068','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020068"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> metasomatism in hydrothermal systems: The Willsboro-Lewis wollastonite ores, New York, USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Whitney, P.R.; Olmsted, J.F.</p> <p>1998-01-01</p> <p>Wollastonite ores and garnet-pyroxene skarns in the Willsboro-Lewis district, New York, USA were formed in a complex hydrothermal system associated with the emplacement of a large anorthosite pluton. Contact-metamorphic marbles were replaced by wollastonite, garnet, and clinopyroxene during infiltration metasomatism involving large volumes of water of chiefly meteoric origin. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in these rocks show large departures from the protolith REE distribution, indicative of substantial REE mobility. Three types of chondrite-normalized REE distribution patterns are present. The most common, found in ores and skarns containing andradite-rich garnet, is convex-up in the light REE (LREE) with a maximum at Pr and a positive Eu anomaly. Europium anomalies and Pr/Yb ratios are correlated with X(Ad) in garnet. This pattern (type C) results from uptake of REE from hydrothermal fluids by growing crystals of calcsilicate minerals, principally andradite, with amounts of LREE controlled by the difference in ionic radius between Ca++ and REE3+ in garnet X sites. The Eu anomaly results either from prior interaction of the fluids with plagioclase-rich, Eu-positive anorthositic rocks in and near the ore zone, or by enrichment of divalent Eu on growth surfaces of garnet followed by entrapment, or both. Relative enrichment in heavy REE (type H) occurs in ores and skarn where calcsilicates, including grossularitic garnet, in contact-metamorphic marble have been concentrated by dissolution of calcite. In most cases a negative Eu anomaly is inherited from the marble protolith. Skarns containing titanite and apatite exhibit high total REE, relative light REE enrichment, and negative Eu anomalies (type L). These appear to be intrusive igneous rocks (ferrodiorites or anorthositic gabbros) that have been converted to skarn by Ca metasomatism. REE, sequestered in titanite, apatite, and garnet, preserve the approximate REE distribution pattern of the igneous protolith. Post-ore granulite facies metamorphism homogenized zoned mineral grains without causing complete intergranular reequilibration and does not appear to have significantly affected the whole-rock REE distributions. These results demonstrate that extensive REE metasomatism can occur in hydrothermal systems at shallow to intermediate depths and that REE <span class="hlt">geochemistry</span> may be useful in discerning the origin of skarns and skarn-related ore deposits.</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 ?M. 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/2014AGUFM.V23D4829N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V23D4829N"><span id="translatedtitle">The Fluid History of Jadeitites Near the Motagua Fault, Guatemala, as Revealed by Stable Isotope and <span class="hlt">Elemental</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>Niespolo, E. M.; Holk, G. J.; Neff, H.</p> <p>2014-12-01</p> <p>Stable isotopes and <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> reveal a complex fluid history for jadeitites exposed both north and south of the Motagua Fault Zone (MFZ) in Guatemala. A companion study (Niespolo et al., 2014) utilized these data to source Mesoamerican jadeitite artifacts, as this region is the only source for such materials. Materials studied include jadeitites that range from 71% to 95% jadeite with minor albite and white mica. Jadeitites north of the MFZ have ?18OJadeite = +9.20.6 (n=6), ?18OAlbite = +9.40.3 (n=2), ?18OWhiteMica = +9.80.3 (n=3), and ?DWhiteMica = -52 4 (n=3). Jadeite ?18O values are 2-5 higher than those reported by Johnson and Harlow (1999), suggesting a diverse fluid history north of the MFZ. Water in apparent equilibrium at 400C with north MFZ jadeitite has ?18O = +8.5 and ?D = -25. Jadeites from Carrizal Grande south of the MFZ have ?18OJadeite = +6.80.6 (n=7), ?18OWhiteMica = +9.01.2 (n=6), and ?DWhiteMica = -422 (n=5), with ?18OH2O = +6.4 and ?DH2O = -15. In contrast, jadeitites from La Cieba south of the MFZ have ?18OJadeite = +7.51.4 (n=5), ?18OAlbite = +9.0, ?18OWhiteMica = +9.70.1 (n=2), and ?DWhiteMica = -420 (n=2), with ?18OH2O = +7.2 and ?DH2O = -14. Calculated fluids are consistent with those associated with the alteration of serpentinite in a subduction zone setting (e.g., Harlow and Sorenson, 2005). White mica, albite and jadeite are out of 18O/16O equilibrium. This suggests post-jadeite isotopic exchange, possibly during exhumation. North MFZ jadeites are enriched in Rb, Ba, Sc, Pb and Nd, and depleted in Sr, Ti, V, and Cr relative to chondrites. Carrizal Grande jadeites are depleted in Sr, Zr, V, and Cr, and enriched in REE and Rb.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUSM.B41A..02R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSM.B41A..02R"><span 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 environments leading to preferential removal of MREE and LREE by adsorption and precipitation as Fe-Mn oxy-hydroxides in sediments. PAAS normalised plots also depicted slightly convex sub-parallel shale like patterns with alike enrichment.The same characteristics have been observed for sediments for Kaveri River validating that the sediments brought down during fluvial transport, is the source of REE in Pichavaram. Strong positive Eu anomalies suggested prevalence of reducing conditions as well as it indicated source from the natural weathering of the post Archean charnockitic and gneissic terrain in the course of river Kaveri. Role of different mangroves species in controlling the REE distribution in sediments was also observed . Tidally influenced cores showed complexity of environment these sites were exposed to. Factor analysis delineated three main processes controlling REE distribution in Pichavaram, namely natural weathering, inherent physico-chemical processes and in-situ biogeochemical processes occurring in this hypersaline mangrove environment.</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 the surrounding host rocks. Where allanite and fluorapatite are texturally related, the fluorapatite is relatively depleted in the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREEs), whereas allanite is relatively LREE enriched, suggesting co-crystallisation. We tentatively date the BX1 ore stage to 1440 ± 80 Ma based on U-Pb dating of thorianite. Sm-Nd isotope isochrons derived from in situ isotope analysis of cognate apatite and allanite date the BX2 and BX3 events to ca. 400 Ma, while U-Pb dating of late-stage monazite from the BX4 ore stage returned an age of ca. 350 Ma. Therefore, formation of the central zone at Nolans Bore involved multiple alteration/brecciation events that collectively span over 1 billion years in duration. We suggest that the BX1-type veins and breccias were formed from REE-rich, saline (F- and Cl-bearing) fluids that infiltrated the granulite-grade host rocks in association with either shear activation events of the Redbank Shear Zone (1500-1400 Ma) or intrusion of late-stage pegmatites of the Mt Boothby area. BX2, BX3, and BX4 events record deformation and hydrothermal alteration associated with the Alice Springs Orogeny (400-350 Ma). These hydrothermal events occurred at temperatures of 450 to ~600 °C, due to inflow of highly acidic hydrous fluids derived from a magmatic source, or from mixing of meteoric and metamorphic fluids. Our data testify to the long and complex geological history of not only the Nolans Bore REE deposit, but also of the rocks of the eastern Reynolds Range, and demonstrate the great utility of using hydrothermally derived REE minerals to trace the timing of crustal deformation events and source of associated hydrothermal fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/2012/1016/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/2012/1016/"><span id="translatedtitle">Review of rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in oil shales of the Eocene Green River Formation</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Birdwell, Justin E.</p> <p>2012-01-01</p> <p>Concentrations of the lanthanide series or rare <span class="hlt">earth</span> <span class="hlt">elements</span> and yttrium were determined for lacustrine oil shale samples from the Eocene Green River Formation in the Piceance Basin of Colorado and the Uinta Basin of Utah. Unprocessed oil shale, post-pyrolysis (spent) shale, and leached shale samples were examined to determine if oil-shale processing to generate oil or the remediation of retorted shale affects rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations. Results for unprocessed Green River oil shale samples were compared to data published in the literature on reference materials, such as chondritic meteorites, the North American shale composite, marine oil shale samples from two sites in northern Tibet, and mined rare <span class="hlt">earth</span> <span class="hlt">element</span> ores from the United States and China. The Green River oil shales had lower rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations (66.3 to 141.3 micrograms per gram, μg g-1) than are typical of material in the upper crust (approximately 170 μg g-1) and were also lower in rare <span class="hlt">earth</span> <span class="hlt">elements</span> relative to the North American shale composite (approximately 165 μg g-1). Adjusting for dilution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> by organic matter does not account for the total difference between the oil shales and other crustal rocks. Europium anomalies for Green River oil shales from the Piceance Basin were slightly lower than those reported for the North American shale composite and upper crust. When compared to ores currently mined for rare <span class="hlt">earth</span> <span class="hlt">elements</span>, the concentrations in Green River oil shales are several orders of magnitude lower. Retorting Green River oil shales led to a slight enrichment of rare <span class="hlt">earth</span> <span class="hlt">elements</span> due to removal of organic matter. When concentrations in spent and leached samples were normalized to an original rock basis, concentrations were comparable to those of the raw shale, indicating that rare <span class="hlt">earth</span> <span class="hlt">elements</span> are conserved in processed oil shales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://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/abs/2016E%26PSL.435..136W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.435..136W"><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, thus, their abundances in the bulk <span class="hlt">Earth</span> likely reflect the average composition of <span class="hlt">Earth</span>'s building materials. Combined with evidence from nucleosynthetic isotope anomalies, the data suggest that <span class="hlt">Earth</span>'s main building materials originated from compartments of the inner solar system where volatile <span class="hlt">element</span> abundances evolved differently from the formation area of known chondrites. The materials with nonchondritic volatile <span class="hlt">element</span> composition may have been used up for building the terrestrial planets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=251706&keyword=rock&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=55737400&CFTOKEN=33226243','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=251706&keyword=rock&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=55737400&CFTOKEN=33226243"><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://pubs.er.usgs.gov/publication/70020241','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020241"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in weathering profiles and sediments of Minnesota: Implications for provenance studies</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morey, G.B.; Setterholm, D.R.</p> <p>1997-01-01</p> <p>The relative abundance of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in sediments has been suggested as a tool for determining their source rocks. This correlation requires that weathering, erosion, and sedimentation do not alter the REE abundances, or do so in a predictable manner. We find that the rare <span class="hlt">earth</span> <span class="hlt">elements</span> are mobilized and fractionated by weathering, and that sediments derived from the weathered materials can display modifications of the original pattern of rare <span class="hlt">earth</span> <span class="hlt">elements</span> of some due to grain-size sorting of the weathered material. However, the REE distribution pattern of the provenance terrane can be recognized in the sediments.</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/2014CoMP..167.1002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014CoMP..167.1002S"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of ultrahigh-pressure anatexis: fractionation of <span class="hlt">elements</span> in the Kokchetav gneisses during melting at diamond-facies conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stepanov, Aleksandr S.; Hermann, Joerg; Korsakov, Andrey V.; Rubatto, Daniela</p> <p>2014-05-01</p> <p>The Kokchetav complex in Kazakhstan contains garnet-bearing gneisses that formed by partial melting of metasedimentary rocks at ultrahigh-pressure (UHP) conditions. Partial melting and melt extraction from these rocks is documented by a decrease in K2O and an increase in FeO + MgO in the restites. The most characteristic trace <span class="hlt">element</span> feature of the Kokchetav UHP restites is a strong depletion in light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE), Th and U. This is attributed to complete dissolution of monazite/allanite in the melt and variable degree of melt extraction. In contrast, Zr concentrations remain approximately constant in all gneisses. Using experimentally determined solubilities of LREE and Zr in high-pressure melts, these data constrain the temperature of melting to ~1,000 °C. Large ion lithophile <span class="hlt">elements</span> (LILE) are only moderately depleted in the samples that have the lowest U, Th and LREE contents, indicating that phengite retains some LILE in the residue. Some restites display an increase in Nb/Ta with respect to the protolith. This further suggests the presence of phengite, which, in contrast to rutile, preferentially incorporates Nb over Ta. The trace <span class="hlt">element</span> fractionation observed during UHP anatexis in the Kokchetav gneisses is significantly different from depletions reported in low-pressure restites, where generally no LREE and Th depletion occurs. Melting at UHP conditions resulted in an increase in the Sm/Nd ratio and a decoupling of the Sm-Nd and Lu-Hf systems in the restite. Further subduction of such restites and mixing with mantle rocks might thus lead to a distinct isotopic reservoir different from the bulk continental crust.</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; Chron, 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 ?REE = 109 86 ppm (mean s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 150 ppm; mean s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display ?Nd values that typically range between the ?Nd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter (inferred from the analysis of local surface seawater). A notable exception is the case of organic matter (OM) fractions leached from cold seep sediment samples, which sometimes exhibit ?Nd values markedly different from both terrigenous and surface seawater signatures. This suggests that a significant fraction of organic compounds in these sediments may be derived from chemosynthetic processes, recycling pore water REE characterized by a distinct isotopic composition. Overall, our results confirm that organic matter probably plays an important role in the oceanic REE budget, through direct scavenging and remineralization within the water column. Both the high REE abundances and the shape of shale-normalized patterns for leached SOM also suggest that OM degradation in sub-surface marine sediments during early diagenesis could control, to a large extent, the distribution of REE in pore waters. Benthic fluxes of organic-bound REE could hence substantially contribute to the exchange processes between particulates and seawater that take place at ocean margins. Neodymium isotopes could provide useful information for tracing the origin (terrestrial versus marine) and geographical provenance of organic matter, with potential applications in paleoceanography. In particular, future studies should further investigate the potential of Nd isotopes in organic compounds preserved in sedimentary records for reconstructing past variations of surface ocean circulation.</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=62277983&CFTOKEN=46566660','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=62277983&CFTOKEN=46566660"><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://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://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/2060/20140003556','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/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 ?PGE (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, Os and Ru concentrations range from 0.6 to 2.2 ppb, 0.2 to 0.6 ppb and 1.4 to 2.6 ppb respectively in IPGE. The PGE abundances in Bababudan komatiites were controlled by olivine fractionation whereas that in Gadwal boninites were influenced by fractionation of chromite and sulphides. The Al-undepleted Bababudan komatiites are characterized by low CaO/Al2O3, (Gd/Yb)N, (La/Yb)N, with positive Zr, Hf, Ti anomalies and high Cu/Pd, Pd/Ir ratios at low Pd concentrations suggesting the derivation of parent magma by high degrees (>30%) partial melting of mantle under anhydrous conditions at shallow depth with garnet as a residual phase in the mantle restite. The komatiites are geochemically analogous to Al-undepleted Munro type komatiites and their PGE compositions are consistent with Alexo and Gorgona komatiites. The S-undersaturated character of Bababudan komatiites is attributed to decompression and assimilation of lower crustal materials during magma ascent and emplacement. In contrast, the higher Al2O3/TiO2, lower (Gd/Yb)N, for Gadwal boninites in combination with negative Nb, Zr, Hf, Ti anomalies and lower Cu/Pd at relatively higher Pd/Ir and Pd concentrations reflect high degree melting of refractory mantle wedge under hydrous conditions in an intraoceanic subduction zone setting. Higher Pd/Ir ratios and S-undersaturation of these boninites conform to influx of fluids derived by dehydration of subducted slab resulting into high fluid pressure and metasomatism of mantle wedge.</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://adsabs.harvard.edu/abs/1985JGR....90.8743C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985JGR....90.8743C"><span id="translatedtitle">Trace <span class="hlt">element</span> and isotopic <span class="hlt">geochemistry</span> of lavas from Haleakala Volcano, east Maui, Hawaii: Implications for the origin of Hawaiian basalts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Chu-Yung; Frey, Frederick A.</p> <p>1985-09-01</p> <p>Haleakala volcano on East Maui, Hawaii, consists of a tholeiitic basalt shield which grades into a younger alkalic series that was followed by a posterosional alkalic series. Tholeiitic, transitional, and alkalic basalts range widely in Sr and Nd isotopic ratios (from mid-ocean ridge basalt to bulk <span class="hlt">earth</span> ratios) and incompatible <span class="hlt">element</span> (P, K, Rb, Sr, Zr, Nb, Ba, REE, Hf, Ta, and Th) abundances, but isotopic ratios and incompatible <span class="hlt">element</span> abundance ratios (e.g., Ba/La, Nb/La, La/Ce, La/Sm) vary systematically with age. The youngest series (posterosional alkalic lavas) has the highest Rb/Sr, Ba/La, Nb/La, La/Ce, and 143Nd/144Nd ratios and the lowest 87sr/86sr ratios, whereas the oldest series (dominantly tholeiitic basalts) has the lowest Rb/Sr, Ba/La, Nb/La, La/Ce, and 143Nd/144Nd ratios and the highest 87sr/86sr ratios. The most striking features of the trace <span class="hlt">element</span> and isotopic data are the inverse correlations between isotopic ratios and parent/daughter abundance ratios in the Sr and Nd systems. Although some of the geochemical variations can be explained by shallow level fractional crystallization (e.g., alkali basalt to mugearite [Chen et al., 1984, and manuscript in preparation, 1985]), the temporal geochemical trends require a major role for mixing. We propose a model in which melts from a diaper interact with incipient melts of its wall rocks, presumed to be oceanic lithosphere. Because of motion between the lithosphere and mantle hot spot the relative contribution of melts from the diapir (mantle plume) material to the lavas decreases with time; consequently, with decreasing age the basalts become more enriched in incompatible trace <span class="hlt">elements</span> and acquire Sr and Nd isotopic ratios which overlap with mid-ocean ridge basalts. This model quantitatively explains the isotopic ratios and incompatible trace <span class="hlt">element</span> abundances in representative samples from the three Haleakala volcanic series. On the basis of the degrees of melting inferred for the mixing components we conclude that the lower lithosphere and much of the asthenosphere beneath Hawaiian volcanoes are involved in creating these volcanoes.</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/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.ars.usda.gov/research/publications/Publications.htm?seq_no_115=139557','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=139557"><span id="translatedtitle">RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENT</span> OXIDES FOR TRACING SEDIMENT MOVEMENT</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 development of soil conservation plans and evaluation of spatially distributed erosion models require knowledge of rates of soil loss and sedimentation on different landscape <span class="hlt">elements</span> and slope positions. Characterization of soil erosion rates and patterns within watersheds is important for the ...</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 records long residence times at eclogite-facies conditions for the UHProcks of North-East Greenland. This spread in observed ages is interpreted to be characteristic of metamorphic rocks that have experienced relatively long (longer than 10 m.y.) residence times at UHP conditions. ?? 2006 Geological Society of America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005GeCoA..69.1607P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005GeCoA..69.1607P"><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>New analyses of highly siderophile <span class="hlt">elements</span> (HSE; Re, Os, Ir, Ru, Pt, and Pd) obtained by Carius tube digestion isotope dilution inductively coupled plasma mass-spectrometry (ID-ICPMS) technique are reported for 187Os-enriched 2.8 Ga komatiites from the Kostomuksha greenstone belt. As a result of a significant improvement in the yield over our previous digestions by the NiS fire-assay technique, these komatiites have now been shown to contain 22 to 25% more Os, Ir, and Pt and 34% more Ru. The emplaced komatiite lavas at Kostomuksha thus had siderophile <span class="hlt">element</span> abundances comparable to those of the Abitibi belt. The discrepancies observed between the two techniques are interpreted to be the result of incomplete digestion of HSE carriers (particularly chromite) during the NiS fire-assay procedure. Our results for UB-N peridotite reference material agree well with those obtained by the high-pressure ashing digestion ID-ICPMS technique reported in the literature. Two types of komatiite lavas have been distinguished in this study based on the IPGE (Os, Ir, and Ru) behavior during lava differentiation. The Kostomuksha type is unique and is characterized by an incompatible behavior of IPGEs, with bulk solid-liquid partition coefficients for IPGEs being close to those for olivine. Cumulate zones in this type of komatiite lava occupy <20% of the total thickness of the flows. The Munro type exhibits a compatible behavior of IPGEs during lava differentiation. The cumulate zone in this type of komatiite occupies >20% of the total thickness of the flows. The calculated bulk partition coefficients indicate that, as with the other Munro-type komatiite lavas, the bulk cumulate contained an IPGE-rich minor phase(s) in addition to olivine. The non-CI chondritic HSE pattern for the source of the Kostomuksha komatiites calculated here is similar to that of Abitibi komatiites and to average depleted spinel lherzolite (ADSL) and supports the hypothesis of a non-CI chondritic HSE 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://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 pH and high chloride concentrations, simulated gastric fluids are most efficient at solubilizing metals such as Hg, Pb, Zn, and others that form strong chloride complexes; although these metals tend to partially reprecipitate in the near-neutral simulated intestinal fluids, complexes with organic ligands (i.e., amino and carboxylic acids) enhance their solubility. These metals are also quite soluble in near-neutral, protein-rich plasma-based fluids because they form strong complexes with the proteins. In contrast, metalloids that form oxyanion species (such as As, Cr, Mo, W) are commonly more soluble in near-neutral pH simulated lung fluids than in simulated gastric fluids.</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://www.ncbi.nlm.nih.gov/pubmed/26222789','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26222789"><span id="translatedtitle">Mobile DNA <span class="hlt">Elements</span>: The Seeds of Organic Complexity on <span class="hlt">Earth</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Habibi, Laleh; Pedram, Mehrdad; AmirPhirozy, Akbar; Bonyadi, Khadijeh</p> <p>2015-10-01</p> <p>Mobile DNA or transposable <span class="hlt">elements</span> (TEs) are genomic sequences capable of moving themselves independently into different parts of the genome. Viral invasion of eukaryotic genomes is assumed to be the main source of TEs. Selfish transposition of these <span class="hlt">elements</span> could be a serious threat to the host cell, as they can insert themselves into the middle of coding genes and/or induce genomic instability. In response, through millions of years of evolution, cells have come up with various mechanisms such as genomic imprinting, DNA methylation, heterochromatin formation, and RNA interference to deactivate them. Interestingly, these processes have also greatly contributed to important cellular functions involved in cell differentiation, development, and differential gene expression. Propagation of TE copies during the course of evolution have resulted in increasing the genome size and providing proper space and flexibility in shaping the genome by creating new genes and establishing essential cellular structures such as heterochromatin, centromere, and telomeres. Yet, these <span class="hlt">elements</span> are mostly labeled for playing a role in pathogenesis of human diseases. Here, we attempt to introduce TEs as factors necessary for making us human rather than just selfish sequences or obligatory guests invading our DNA. PMID:26222789</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19730034958&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730034958&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drare%2Bearth"><span id="translatedtitle">Rare <span class="hlt">earths</span> and other trace <span class="hlt">elements</span> in Apollo 14 samples.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Helmke, P. A.; Haskin, L. A.; Korotev, R. L.; Ziege, K. E.</p> <p>1972-01-01</p> <p>REE and other trace <span class="hlt">elements</span> have been determined in igneous rocks 14053, 14072, and 14310, in breccias 14063 and 14313, and in fines 14163. All materials analyzed have typical depletions of Eu except for feldspar fragments from the breccias and igneous fragments from 14063. Igneous rocks 14072 and 14053 have REE concentrations very similar to Apollo 12 basalts; 14310 has the highest REE concentrations yet observed for a large fragment of lunar basalt. The effects of crystallization of a basaltic liquid as a closed system on the concentrations of Sm and Eu in feldspar are considered. Small anorthositic fragments may have originated by simple crystallization from very highly differentiated basalt (KREEP) or by closed-system crystallization in a less differentiated starting material. Application of independent models of igneous differentiation to Sm and Eu in massive anorthosite 15415 and to Sm and Eu in lunar basalts suggests a common starting material with a ratio of concentrations of Sm and Eu about the same as that in chondrites and with concentrations of those <span class="hlt">elements</span> about 15 times enriched over chondrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://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>2016-01-01</p> <p>Reduction of [Cp*Fe(η(5) -As5 )] with [Cp''2 Sm(thf)] (Cp''=η(5) -1,3-(tBu)2 C5 H3 ) under various conditions led to [(Cp''2 Sm)(μ,η(4) :η(4) -As4 )(Cp*Fe)] and [(Cp''2 Sm)2 As7 (Cp*Fe)]. Both compounds are the first polyarsenides of the rare-<span class="hlt">earth</span> metals. [(Cp''2 Sm)(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''2 Sm)2 As7 (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''2 Sm)(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://www.ncbi.nlm.nih.gov/pubmed/25430011','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25430011"><span id="translatedtitle">Levels of major and trace <span class="hlt">elements</span>, including rare <span class="hlt">earth</span> <span class="hlt">elements</span>, and ²³⁸U in Croatian tap waters.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fiket, Željka; Rožmarić, Martina; Krmpotić, Matea; Benedik, Ljudmila</p> <p>2015-05-01</p> <p>Concentrations of 46 <span class="hlt">elements</span>, including major, trace, and rare <span class="hlt">earth</span> <span class="hlt">elements</span>, and (238)U in Croatian tap waters were investigated. Selected sampling locations include tap waters from various hydrogeological regions, i.e., different types of aquifers, providing insight into the range of concentrations of studied <span class="hlt">elements</span> and (238)U activity concentrations in Croatian tap waters. Obtained concentrations were compared with the Croatian maximum contaminant levels for trace <span class="hlt">elements</span> in water intended for human consumption, as well as WHO and EPA drinking water standards. Concentrations in all analyzed tap waters were found in accordance with Croatian regulations, except tap water from Šibenik in which manganese in concentration above maximum permissible concentration (MPC) was measured. Furthermore, in tap water from Osijek, levels of arsenic exceeded the WHO guidelines and EPA regulations. In general, investigated tap waters were found to vary considerably in concentrations of studied <span class="hlt">elements</span>, including (238)U activity concentrations. Causes of variability were further explored using statistical methods. Composition of studied tap waters was found to be predominately influenced by hydrogeological characteristics of the aquifer, at regional and local level, the existing redox conditions, and the household plumbing system. Rare <span class="hlt">earth</span> <span class="hlt">element</span> data, including abundances and fractionation patterns, complemented the characterization and facilitated the interpretation of factors affecting the composition of the analyzed tap waters. PMID:25430011</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/2014MinPe.108..419F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MinPe.108..419F"><span id="translatedtitle">Platinum-group <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Zhuqing Fe-Ti-V oxide ore-bearing mafic intrusions in western Yangtze Block, SW China: control of platinum-group <span class="hlt">elements</span> by magnetite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fan, Hong-Peng; Zhu, Wei-Guang; Zhong, Hong; Bai, Zhong-Jie; He, De-Feng; Ye, Xian-Tao; Chen, Cai-Jie; Cao, Chong-Yong</p> <p>2014-06-01</p> <p>Platinum-group <span class="hlt">element</span> (PGE) <span class="hlt">geochemistry</span> combined with <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> and magnetite compositions are reported for the Mesoproterozoic Zhuqing Fe-Ti-V oxide ore-bearing mafic intrusions in the western Yangtze Block, SW China. All the Zhuqing gabbros display extremely low concentrations of chalcophile <span class="hlt">elements</span> and PGEs. The oxide-rich gabbros contain relatively higher contents of Cr, Ni, Ir, Ru, Rh, and lower contents of Pt and Pd than the oxide-poor gabbros. The abundances of whole-rock concentrations of Ni, Ir, Ru, and Rh correlate well with V contents in the Zhuqing gabbros, implying that the distributions of these <span class="hlt">elements</span> are controlled by magnetite. The fractionation between Ir-Ru-Rh and Pt-Pd in the Zhuqing gabbros is mainly attributed to fractional crystallization of chromite and magnetite, whereas Ru anomalies are mainly due to variable degrees of compatibility of PGE in magnetite. The order of relative incompatibility of PGEs is calculated to be Pd < Pt < Rh < Ir < Ru. The very low PGE contents and Cu/Zr ratios and high Cu/Pd ratios suggest initially S-saturated magma parents that were highly depleted in PGE, which mainly formed due to low degrees of partial melting leaving sulfides concentrating PGEs behind in the mantle. Moreover, the low MgO, Ni, Ir and Ru contents and high Cu/Ni and Pd/Ir ratios for the gabbros suggest a highly evolved parental magma. Fe-Ti oxides fractionally crystallized from the highly evolved magma and subsequently settled in the lower sections of the magma chamber, where they concentrated and formed Fe-Ti-V oxide ore layers at the base of the lower and upper cycles. Multiple episodes of magma replenishment in the magma chamber may have been involved in the formation of the Zhuqing intrusions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=mining+AND+sampling&id=EJ276909','ERIC'); return false;" href="http://eric.ed.gov/?q=mining+AND+sampling&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://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.ncbi.nlm.nih.gov/pubmed/26263628','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26263628"><span id="translatedtitle">[Leaching of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from Coal Ashes Using Acidophilic Chemolithotrophic Microbial Communities].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Muravyov, M I; Bulaev, A G; Melamud, V S; Kondrat'eva, T F</p> <p>2015-01-01</p> <p>A method for leaching rare <span class="hlt">earth</span> <span class="hlt">elements</span> from coal ash in the presence of <span class="hlt">elemental</span> sulfur using communities of acidophilic chemolithotrophic microorganisms was proposed. The optimal parameters determined for rare <span class="hlt">element</span> leaching in reactors were as follows: temperature, 45 degrees C; initial pH, 2.0; pulp density, 10%; and the coal ash to <span class="hlt">elemental</span> sulfur ratio, 10 : 1. After ten days of leaching, 52.0, 52.6, and 59.5% of scandium, yttrium, and lanthanum, respectively, were recovered. PMID:26263628</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-rich inclusions, which have large negative Ce and small negative Pr anomalies [7], probably formed by extremely rapid evaporation in the solar nebula or by evaporation in an environment much poorer in hydrogen. Normal CAIs do not have Ce anomalies. If they experienced evaporation in the solar nebula, the process must have occurred slowly enough to maintain reducing conditions in the residue. References: [1] Davis A. M. et al. (1990) Nature, 347, 655-658. [2] Boynton W. V. (1975) GCA, 39, 569-584. [3] Davis A. M. and Grossman L. (1979) GCA, 43, 1611-1632. [4] Hashimoto A. (1990) Nature, 347, 53-55. [5] Hashimoto A. (1983) Geochem. J., 17, 111-145. [6] Davis A. M. et al. (1982) GCA, 46, 1627-1651. [7] Ireland T. R. et al. (1992) GCA, 56, 2503-2520. Figure 1, which appears in the hard copy, shows fraction remaining vs. percent evaporated for vacuum evaporation of material of chondritic composition.</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=19750003762&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750003762&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drare%2Bearth"><span id="translatedtitle">Determination of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in Luna 16 regolith sample by chemical spectral method</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stroganova, N. S.; Ryabukhin, V. A.; Laktinova, N. V.; Ageyeva, L. V.; Galkina, I. P.; Gatinskaya, N. G.; Yermakov, A. N.; Karyakin, A. V.</p> <p>1974-01-01</p> <p>An analysis was made of regolith from layer A of the Luna 16 sample for rare <span class="hlt">earth</span> <span class="hlt">elements</span>, by a chemical spectral method. Chemical and ion exchange concentrations were used to determine the content of 12 <span class="hlt">elements</span> and Y at the level 0.001 to 0.0001 percent with 10 to 15 percent reproducibility of the emission determination. Results within the limits of reproducibility agree with data obtained by mass spectra, activation, and X-ray fluorescent methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1236947','SCIGOV-STC'); 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/scitech">SciTech Connect</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810057588&hterms=table+elements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtable%2Belements','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810057588&hterms=table+elements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtable%2Belements"><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.osti.gov/scitech/servlets/purl/1234401','SCIGOV-STC'); 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/scitech">SciTech Connect</a></p> <p>Andrew Fowler</p> <p>2015-07-24</p> <p>Results for fluid rare <span class="hlt">earth</span> elment analyses from Reykjanes wells RN-12 and RN-19. The data have not been corrected for flashing. Samples preconcetrated using chelating resin with IDA functional group (InertSep ME-1). Analyzed using and <span class="hlt">Element</span> magnetic sctor ICP-MS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=279057&keyword=earth&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=55697005&CFTOKEN=47271020','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=279057&keyword=earth&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=55697005&CFTOKEN=47271020"><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/2015RaPC..106..160S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015RaPC..106..160S"><span id="translatedtitle">Total photon attenuation coefficients in some rare <span class="hlt">earth</span> <span class="hlt">elements</span> using selective excitation method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>SitaMahalakshmi, N. V.; Kareem, M. A.; Premachand, K.</p> <p>2015-01-01</p> <p>The total mass attenuation coefficients were measured in the <span class="hlt">elements</span> La, Nd, Sm, Gd and Dy belonging to rare <span class="hlt">earth</span> region in the energy range 30-55 keV by employing the selective excitation method. This method facilitates selection of excitation energies near the K edge. The present experimental results were compared with the theoretical values due to Chantler and XCOM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=272377','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=272377"><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://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47189&keyword=boundary+AND+element+AND+interface&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=57455887&CFTOKEN=55156058','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47189&keyword=boundary+AND+element+AND+interface&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=57455887&CFTOKEN=55156058"><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.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.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://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=256482&keyword=global+AND+business&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=55645647&CFTOKEN=96244674','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=256482&keyword=global+AND+business&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=55645647&CFTOKEN=96244674"><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/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://www.osti.gov/scitech/biblio/5274436','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5274436"><span id="translatedtitle">Relative sensitivity factors for rare <span class="hlt">earth</span> <span class="hlt">elements</span> in different matrices employing spark source mass spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ramakumar, K.L.; Aggarwal, S.K.; Kavimandan, V.D.; Shah, P.M.; Raman, V.A.; Sant, V.L.; Ramasubramanian, P.A.; Jain, H.C.</p> <p>1985-07-01</p> <p>Relative Sensitivity Factors (RSFs) for the rare <span class="hlt">earth</span> <span class="hlt">elements</span> Ce, Nd, Sm, Eu, Gd, Dy, Er, and Lu have been determined in U/sub 3/O/sub 8/-graphite and pure graphite matrices under similar experimental conditions employing Spark Source Mass Spectrometry (SSMS) with electrical detection system in magnetic peak switching mode. The RSF values differ very much when the matrix <span class="hlt">element</span> (uranium in U/sub 3/O/sub 8/-graphite system or carbon in pure graphite) is the reference, but they show very good agreement when Er, one of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> is chosen as internal standard. The literature data on RSF values for the rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Y/sub 2/O/sub 3/ as well as Al matrices are compared with those obtained in the present work. An attempt has been made to explain the similar tend in the RSF values in all these matrices in terms of the decomposition pattern of the rare <span class="hlt">earth</span> oxides. An empirical equation relating the RSFs with the decomposition energies of the lanthanide sesquioxides and monoxides has been shown to be useful in computing the RSFs for the lanthanides in various matrices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26672316','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26672316"><span id="translatedtitle">[Spectroscopic Research on Slag Nanocrystal Glass Ceramics Containing 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>Ouyang, Shun-li; Li, Bao-wei; Zhang, Xue-feng; Jia, Xiao-lin; Zhao, Ming; Deng, Lei-bo</p> <p>2015-08-01</p> <p>The research group prepared the high-performance slag nanocrystal glass ceramics by utilizing the valuable <span class="hlt">elements</span> of the wastes in the Chinese Bayan Obo which are characterized by their symbiotic or associated existence. In this paper, inductively coupled plasma emission spectroscopy (ICP), X-ray diffraction (XRD), Raman spectroscopy (Raman) and scanning electron microscopy (SEM) are all used in the depth analysis for the composition and structure of the samples. The experiment results of ICP, XRD and SEM showed that the principal crystalline phase of the slag nanocrystal glass ceramics containing rare <span class="hlt">earth</span> <span class="hlt">elements</span> is diopside, its grain size ranges from 45 to 100 nm, the <span class="hlt">elements</span> showed in the SEM scan are basically in consistent with the component analysis of ICP. Raman analysis indicated that its amorphous phase is a three-dimensional network structure composed by the structural unit of silicon-oxy tetrahedron with different non-bridging oxygen bonds. According to the further analysis, we found that the rare <span class="hlt">earth</span> microelement has significant effect on the network structure. Compared the nanocrystal slag glass ceramic with the glass ceramics of similar ingredients, we found that generally, the Raman band wavenumber for the former is lower than the later. The composition difference between the glass ceramics and the slag nanocrystal with the similar ingredients mainly lies on the rare <span class="hlt">earth</span> <span class="hlt">elements</span> and other trace <span class="hlt">elements</span>. Therefore, we think that the rare <span class="hlt">earth</span> <span class="hlt">elements</span> and other trace <span class="hlt">elements</span> remains in the slag nanocrystal glass ceramics have a significant effect on the network structure of amorphous phase. The research method of this study provides an approach for the relationship among the composition, structure and performance of the glass ceramics. PMID:26672316</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7093375','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7093375"><span id="translatedtitle">Oceanic crustal thickness from seismic measurements and rare <span class="hlt">earth</span> <span class="hlt">element</span> inversions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>White, R.S.; McKenzie, D.; O'Nions, R.K. )</p> <p>1992-12-10</p> <p>Seismic refraction results show that the igneous section of oceanic crust averages 7.1 [plus minus] 0.8 km thick away from anomalous regions such as fracture zones and hot-spots, with extremal bounds of 5.0-8.5 km. Rare <span class="hlt">earth</span> <span class="hlt">element</span> inversions of the melt distribution in the mantle source region suggest that sufficient melt is generated under normal oceanic spreading centers to produce an 8.3 [plus minus] 1.5 km thick igneous crust. The difference between the thickness estimates from seismics and from rare <span class="hlt">earth</span> <span class="hlt">element</span> inversions is not significant given the uncertainties in the mantle source composition. The inferred igneous thickness increases to 10.3 [plus minus] 1.7 km (seismic measurements) and 10.7 [plus minus] 1.6 km (rare <span class="hlt">earth</span> <span class="hlt">element</span> inversions) where spreading centers intersect the regions of hotter than normal mantle surrounding mantle plumes. This is consistent with melt generation by decompression of the hotter mantle as it rises beneath spreading centers. Maximum inferred melt volumes are found on aseismic ridges directly above the central rising cores of mantle plumes, and average 20 [plus minus] 1 and 18 [plus minus] 1 km for seismic profiles and rare <span class="hlt">earth</span> <span class="hlt">element</span> inversions respectively. Both seismic measurements and rare <span class="hlt">earth</span> <span class="hlt">element</span> inversions show evidence for variable local crustal thinning beneath fracture zones, though some basalts recovered from fracture zones are indistinguishable geochemically from those generated on normal ridge segments away from fracture zones. The authors attribute the decreased mantle melting on very slow-spreading ridges to the conductive heat loss that enables the mantle to cool as it rises beneath the rift.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMDI21A4272D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMDI21A4272D"><span id="translatedtitle">The Fate of Sulfur during Decompression Melting of Peridotite and Crystallization of Basalts - Implications for Sulfur <span class="hlt">Geochemistry</span> of MORB and the <span class="hlt">Earth</span>'s Upper Mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, S.; Dasgupta, R.</p> <p>2014-12-01</p> <p>Magmatism in mid-ocean ridges is the main pathway of sulfur (S) from the <span class="hlt">Earth</span>'s mantle to the surficial reservoir. MORB is generally considered sulfide saturated due to the positive correlation between S and FeOT concentration (e.g., [1]). However, most MORBs are differentiated, and both S content and sulfur concentration at sulfide saturation (SCSS) change with P, T, and magma composition (e.g., [2]). Therefore, it remains uncertain, from the MORB chemistry alone, whether mantle melts parental to MORB are sulfide saturated. In this study, we modeled the behavior of S during isentropic partial melting of a fertile peridotite using pMELTS [3] and an SCSS parameterization [4]. Our results show that during decompression melting, at a fixed mantle potential temperature, TP (e.g., 1300 °C), SCSS of aggregate melt first slightly increases then decreases at shallower depth with total variation <200 ppm. However, an increase of TP results in a significant increase of SCSS of primitive melts. Our model shows that at 15% melting (F), sulfide in the residue is exhausted for a mantle with <200 ppm S. The resulted sulfide-undersaturated partial melts contain <1000 ppm S and are 4-6 times enriched in Cu compared to the source. In order to compare our modeled results directly to the differentiated basalts, isobaric crystallization calculation was performed on 5, 10, and 15% aggregate melts. SCSS changes along liquid line of descent with a decrease in T and increase in FeOT. Comparison of S contents between the model results and MORB glasses [5] reveals that many MORBs derive from sulfide undersaturated melts. Further, for a TP of 1300-1350 °C and F of 10-15 wt.%, reproduction of self-consistent S, and Cu budget of many MORB glasses requires that S of their mantle source be ~25-200 ppm. We will discuss the interplay of TP, average F, and the conditions of differentiation to bracket the S <span class="hlt">geochemistry</span> of MORB and MORB source mantle and develop similar systematics for OIBs and OIB source. References: [1] Le Roux et al. (2006) EPSL, 251, 209-231. [2] Baker and Moritti (2011) Rev. in Mineral. Geochem, 73, 167-213. [3] Ghiorso et al. (2002) Geochem. Geophy. Geosy. 3, 5. [4] Li and Ripley (2009) Econ. Geol. 104, 405-412. [5] Jenner and O'Neill (2012) Geochem. Geophy. Geosy. 13, 1.</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://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://www.osti.gov/scitech/biblio/22280491','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22280491"><span id="translatedtitle">?-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.; Sderstrm, 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 ?-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> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16379301','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16379301"><span id="translatedtitle">[Determination of ten trace rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the sample by atomic emission spectrometry].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Hui-zhi; Zhai, Dian-tang; Zhang, Jin; Pei, Mei-shan</p> <p>2005-09-01</p> <p>This paper describes the determination of trace La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Yb and Lu in the sample, using carbon powder, potassium sulfate, barium sulfate, strontium sulfate, and scandium chloride as buffer, by atomic emission spectrometry (AES). Scandium was selected as internal standard line. Sample separation and chemical treatment were not required. The sample was directly loaded into ordinary electrode. The method is simple, rapid and accurate. The determination requirement and influence factors were studied. A new method was developed for the determination of ten rare <span class="hlt">earth</span> <span class="hlt">elements</span>, for which the detection limit is smaller than 0.030%, and the range of the recovery is 94%-105%. The results of these <span class="hlt">elements</span> in standard sample are in agreement with certified values, and the RSD is smaller than 5% (n = 9). The method has been applied to the determination of ten rare <span class="hlt">earth</span> <span class="hlt">elements</span> with satisfactory results. PMID:16379301</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011E%26PSL.305..309N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011E%26PSL.305..309N"><span id="translatedtitle">Rubidium isotopes in primitive chondrites: Constraints on <span class="hlt">Earth</span>'s volatile <span class="hlt">element</span> depletion and lead isotope evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nebel, O.; Mezger, K.; van Westrenen, W.</p> <p>2011-05-01</p> <p>The bulk silicate <span class="hlt">Earth</span> (BSE) shows substantial deficits in volatile <span class="hlt">elements</span> compared to CI-chondrites and solar abundances. These deficits could be caused by pre-accretionary depletion in the solar nebula during condensation of solids, or by later heat-driven evaporation during collision of small bodies that later accreted to form the <span class="hlt">Earth</span>. The latter is considered to result in isotope fractionation for <span class="hlt">elements</span> with low condensation temperatures that correlates with the degree of depletion. Here, we report first high-precision isotope ratio measurements of the moderately volatile and lithophile trace <span class="hlt">element</span> Rb. Data from seventeen chondrite meteorites show that their Rb isotope abundances are nearly indistinguishable from <span class="hlt">Earth</span>, not deviating more than 1 per mil in their 87Rb/85Rb. The almost uniform solar system Rb isotope pool suggests incomplete condensation or evaporation in a single stage is unlikely to be the cause of the volatile <span class="hlt">element</span> deficit of the <span class="hlt">Earth</span>. As Rb and Pb have similar condensation temperatures, we use their different degrees of depletion in the BSE to address the mechanisms and timing of terrestrial volatile depletion. The Rb isotope data are consistent with a scenario in which the volatile budget of the <span class="hlt">Earth</span> was generated by a mixture of a highly volatile-<span class="hlt">element</span> depleted early Proto-<span class="hlt">Earth</span> with undepleted material in the course of terrestrial accretion. Observed Pb and Rb abundances and U-Pb and Rb-Sr isotope systematics suggest that volatile addition occurred at approximately the same time at which last core-mantle equilibration was achieved. In line with previous suggestions, this last equilibration involved a second stage of Pb (but not Rb) depletion from the BSE. The timing of this second Pb loss event can be constrained to ~ 110 Ma after the start of the solar system. This model supports a scenario with core storage of Pb in the aftermath of a putative Moon forming giant impact that also delivered the bulk of the volatile <span class="hlt">elements</span> to the <span class="hlt">Earth</span>.</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/abs/2014cosp...40E2641P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E2641P"><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://ntrs.nasa.gov/search.jsp?R=19860044210&hterms=earth+moon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dearth%2Bmoon','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860044210&hterms=earth+moon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dearth%2Bmoon"><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://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> <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://www.ncbi.nlm.nih.gov/pubmed/19090098','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19090098"><span id="translatedtitle">Contribution to the <span class="hlt">geochemistry</span> of trace <span class="hlt">elements</span> in the sediments of the Noun River and tributaries, western Cameroon.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Njofang, C; Matschullat, J; Tchouankou, J P; Amougou, A</p> <p>2007-09-15</p> <p>This study reports on the distribution of trace <span class="hlt">elements</span> in the sediments of the Noun River valley. Two groups of trace <span class="hlt">elements</span> have emerged based on their distribution and geochemical behaviour. The first group shows lower values whereas the second group aligns higher values. <span class="hlt">Elements</span> like Al and Sr in one side and Zn, Zr in the other present concentrations statistically different from those of the rocks compared to other <span class="hlt">elements</span> in trace analyzed (Cr, Ni, Ba, Co, Cu, Fe, Mn, V, As and Pb). The trace <span class="hlt">elements</span> Al, Sr, Zr, Zn and Pb in the sediments of the Noun River show concentrations rather lower than those of the world. The average concentrations in <span class="hlt">elements</span> C (3.72%), N (0.27%), S (0.05%) and of the ratios C/N (13.77) and N/S (5.29) reflect those resulting from the decomposition of the organic matter which derives from soils with very small concentrations in S. The Noun valley sediments are mostly of primary (quartz, microcline, plagioclase, orthoclase, ilmenite, anatase) and newly formed or secondary (kaolinite, gibbsite, hematite, goethite) minerals. This mineralogy and the overall low concentration of the studied trace <span class="hlt">elements</span>, with Al, Fe, Ti and Mn as most abundant <span class="hlt">elements</span>, is consistent with the local geology made up of the basic rocks (basalts, volcanic ash) and of the acid rocks (granites, gneiss). Overall the trace <span class="hlt">elements</span> concentration and distribution suggest their geogene origin. Yet, this study is a first contribution of its kind towards the development of a baseline geochemical database essential for a sustainable and healthier Noun valley ecosystem. PMID:19090098</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://pubs.usgs.gov/of/1979/0926/report.pdf','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/1979/0926/report.pdf"><span id="translatedtitle">Major-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Silent Canyon-Black Mountain peralkaline volcanic centers, northwestern Nevada Test Site: applications to an assessment of renewed volcanism</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Crowe, Bruce M.; Sargent, Kenneth A.</p> <p>1979-01-01</p> <p>The Silent Canyon and Black Mountain volcanic centers are located in the northern part of the Nevada Test Site. The Silent Canyon volcanic center is a buried cauldron complex of Miocene age (13-15 m.y.). Black Mountain volcanic center is an elliptical-shaped cauldron complex of late Miocene age. The lavas and tuffs of the two centers comprise a subalkaline-peralkaline association. Rock types range from quartz normative subalkaline trachyte and rhyolite to peralkaline comendite. The Gold Flat Member of the Thirsty Canyon Tuff (Black Mountain) is a pantellerite. The major-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Black Mountain-Silent Canyon volcanic centers differs in the total range and distribution of Si02, contents, the degree of peralkalinity (molecular Na2O+K2O>Al2O3) and in the values of total iron and alumina through the range of rock types. These differences indicate that the suites were unrelated and evolved from differing magma bodies. The Black Mountain volcanic cycle represents a renewed phase of volcanism following cessation of the Timber Mountain-Silent Canyon volcanic cycles. Consequently, there is a small but numerically incalculable probability of recurrence of Black Mountain-type volcanism within the Nevada Test Site region. This represents a potential risk with respect to deep geologic storage of high-level radioactive waste at the Nevada Test Site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11378929','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11378929"><span id="translatedtitle">Radon (222Rn) level variations on a regional scale: influence of the basement trace <span class="hlt">element</span> (U, Th) <span class="hlt">geochemistry</span> on radon exhalation rates.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ielsch, G; Thiblemont, D; Labed, V; Richon, P; Tymen, G; Ferry, C; Rob, M C; Baubron, J C; Bchennec, F</p> <p>2001-01-01</p> <p>The approach proposed in this study provides insight into the influence of the basement <span class="hlt">geochemistry</span> on the spatial distribution of radon (222Rn) levels both at the soil/atmosphere interface and in the atmosphere. We combine different types of in situ radon measurements and a geochemical classification of the lithologies, based on 1/50,000 geological maps, and on their trace <span class="hlt">element</span> (U, Th) contents. The advantages of this approach are validated by a survey of a stable basement area of Hercynian age, located in South Brittany (western France) and characterized by metamorphic rocks and granitoids displaying a wide range of uranium contents. The radon source-term of the lithologies, their uranium content, is most likely to be the primary parameter which controls the radon concentrations in the outdoor environment. Indeed, the highest radon levels (> or = 100 Bq m-3 in the atmosphere, > or = 100 mBq m-2 s-1 at the surface of the soil) are mostly observed on lithologies whose mean uranium content can exceed 8 ppm and which correspond to peraluminous leucogranites or metagranitoids derived from uraniferous granitoids. PMID:11378929</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JSAES..37..136R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JSAES..37..136R"><span id="translatedtitle">Provenance of late Oligocene to quaternary sediments of the Ecuadorian Amazonian foreland basin as inferred from major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and Nd-Sr isotopic composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roddaz, Martin; Christophoul, Frdric; Burgos Zambrano, Jos David; Soula, Jean-Claude; Baby, Patrice</p> <p>2012-08-01</p> <p>Oligocene to Quaternary deposits from the Oriente Amazonian foreland basin (Ecuador and Peru) were analyzed for major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> (46 and 32 samples respectively) and Nd-Sr isotopic systematics (n = 10). Chemical Index of Alteration values lower than those of other Amazonian foreland basin sediments and scattering along the AK join in the A-CN-K diagram indicate that the Oriente foreland basin has been continuously fed by poorly to moderately weathered sediments having an overall Andesitic composition since the Oligocene. Chemical ratios such as Cr/Th and Th/Sc as well as Eu anomaly and Nd-Sr isotopic compositions indicate that most of the analyzed sediments contained a greater proportion of volcanic arc rock material than the other Amazonian foreland basin sediments. When compared with the older sediments The Quaternary sediments are characterized by a greater contribution of the volcanic arc source. The composition of the sediments deposited in the Ecuadorian Amazonian foreland basin is mainly controlled by geodynamic processes. We suspect the Late Pliocene-Pleistocene subduction of the Carnegie ridge to be responsible for the back arc volcanism feeding the Amazonian foreland with more basic materials. Input of young Ecuadorian volcanic rocks may explain the difference in Sr and Nd isotopic ratios of suspended sediments between the Solimoes and the Madeira rivers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('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 positive Ce anomalies are likely due to partially oxidative scavenging of Ce(III) to Ce(IV), and HREE enrichment would result from preferential scavenging of the LREEs relative to the HREEs during Fe/Mn oxides/oxyhydroxides precipitations, which is well supported by the low concentrations of dissolved Fe and Mn. In the down-gradient (Zone II and Zone III), reductive dissolution of Fe/Mn oxides/oxyhydroxides increases positive Ce anomalies along the flow path. The positive correlations between (Er/Nd)NASC values and dissolved Fe/Mn concentrations suggest that reductive dissolution of Fe/Mn oxides/oxyhydroxides, as well as readsorption, are the geochemical controls on groundwater REE fractionation patterns. Groundwaters mostly have positive Eu anomalies (Eu/Eu∗ = EuNASC/(SmNASC × GdNASC)0.5), which would be the result of chemical weathering of feldspars (e.g., plagioclase) detected in aquifer sediments by XRD technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15091753','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15091753"><span id="translatedtitle">Long-term changes in <span class="hlt">elemental</span> deposition at the <span class="hlt">earth</span>'s surface.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brimblecombe, P</p> <p>1994-01-01</p> <p>The rate of deposition of <span class="hlt">elements</span> at a point on the <span class="hlt">earth</span>'s surface can change, quite dramatically, even on relatively short time-scales, as a function of weather patterns. On a global scale volcanoes (and more rarely large meteors) can overwhelm steadier sources of trace <span class="hlt">elements</span>. In recent centuries human activities have increased emissions to the atmosphere to a point where they are above those of natural sources for some of the rarer <span class="hlt">elements</span>. On a longer time-scale climate change can also alter the deposition of <span class="hlt">elements</span>, although such changes are often slower than those brought about through anthropogenic emissions. Changes in climate can also alter the distribution of deposition, but there are few studies estimating such changes. This paper uses estimates of the balance of natural and anthropogenic sources of a range of <span class="hlt">elements</span> to examine the likely variation in deposition at the <span class="hlt">earth</span>'s surface. It particularly focuses on those <span class="hlt">elements</span> regarded as toxic, whose concentrations seem likely to go on increasing in industrial areas. PMID:15091753</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/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 true partition coefficient (Kd actual) is significantly higher. Importantly, the Kd of NOM-metal complexes [organic carbon-metal ratio) approaches 1 for the most stable aqueous complexes, as is shown here for Co, but has values of 24-150 for V, Ni and Cu. This implies that ternary surface complexation (metal-ligand co-adsorption) can occur (as for NOM-Co), but is the exception rather than the rule. We also demonstrate the potential for trace metals to record information on NOM composition as expressed through changing NOM-metal complexation patterns in dripwaters. Therefore, a suite of trace metals in stalagmites show variations clearly attributable to changes in organic ligand concentration and composition, and which potentially reflect the state of overlying surface ecosystems. The heterogeneous speciation and size distribution of aqueous NOM and metals (Lead and Wilkinson, 2006; Aiken et al., 2011). The variability in NOM-metal transport in caves that arises from the interaction between infiltration, flow routing, and the hydrodynamic properties of the fine colloids and particulates (Hartland et al., 2012). Variable dissociation kinetics through time as a function of (a) (Hartland et al., 2011). The surface charge of calcite and the availability of CaCO3 lattice sites as well as increased incidence of crystallographic defects with implications for incorporation of a range of trace species (Fairchild and Treble, 2009; Fairchild and Hartland, 2010). Thus, incorporation in speleothem calcite with consistent surface site properties will be determined by: The size and composition (i.e. hydrophilicity/hydrophobicity) of the NOM ligand, affecting adsorption and stability at the calcite surface. The lability (i.e. exchangeability) of the complexed metal and its binding affinity for the calcite surface. The concentration of aqueous complexes. Given the complexities, a partitioning approach to the problem is appropriate as a first approximation rather than a precise description. This study seeks to make the first quantitative connection between the organic and inorganic compositions of speleothems and thus determine the potential for speleothems to encode fluctuations in colloid-facilitated trace metal transport in karst aquifers. Recent findings of direct relevance to the present studyThe conjugate dripwater (PE1) to the stalagmite studied here (PC-08-1) was characterised in June 2009 using an array of complementary techniques, in which the size, speciation and lability of NOM-metal complexes was characterised (Hartland et al., 2011), where lability is defined as the capacity for complexes to dissociate in the context of the on-going interfacial process at the stalagmite surface. In PE1 dripwater, the most stable aqueous complexes were formed between Co and the finest, low molecular weight component of the NOM spectrum (Hartland et al., 2011). Speciation experiments demonstrated that Co was essentially non-exchangeable (free metal (fm) = <0.05), being retained in aqueous complexes, whilst Cu, Ni and V were all predominantly bound by NOM (fm = 0.2-0.3).In contrast, Sr and Ba were freely exchangeable between the solution and solid phase (Hartland et al., 2011) and Mg was absent, presumably due to the poor solubility of Mg(OH)2 at hyperalkaline pH (Ksp = 1.5 × 10-11): Mg2+(aq)+2OH-(aq)↔Mg( On the other hand, the transition metals were not lost as insoluble hydroxides (Hartland et al., 2012), despite having lower solubility than Mg (e.g. Cu(OH)2Ksp = 2.2 × 10-20); and this is consistent with the dominant role of NOM in solubilising and transporting the transition metals in this system (Hartland et al., 2011).The transport of metals by complexes with NOM in PE1 dripwater through the hydrological year was studied by Hartland et al. (2012). This study had two findings of direct relevance to the study of trace metal variations in the conjugate PC-08-1 stalagmite: Complexes between metals and the smallest, low-molecular weight fraction of NOM showed an attenuated delivery in dripwaters consistent with the non-conservative behaviour of analogous tracers in fractured-rock studies due to diffusion into micro-fractures. This mode of transport was termed ‘low-flux’ and was the dominant mode of transport for Co and V. Complexes between metals and coarse colloids (>100 nm) and particulates (>1000 nm) showed a rapid responsiveness to infiltration events. This was termed the ‘high-flux’ mode of NOM-metal transport and was interpreted as being dominantly fracture-fed. This mode of transport was dominated by Cu, Zn and Ni. The ‘high-flux’ vs ‘low-flux’ interplay of trace metal transport is summarised in Fig. 1.The PC-08-1 stalagmite studied here was deposited following the removal of stalagmite PC-97-1 studied by Baker et al. (1999b) and which grew under the PE1 drip point between 1927 and 1997. Both the PC-97-1 stalagmite and its regrowth (PC-08-1) are characterised by annual lamina couplets consisting of a porous pale layer and a dense fluorescent layer. Fluorescence in the PC-97-1 stalagmite displayed a marked sinusoidal pattern with 10% of laminae exhibiting a double band structure (Baker et al., 1999b).</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 REE relative to the upper continental crust and average shale but the Thar desert has a REE signature distinctly different from all other dust sources. There are significant differences in major, trace and REE compositions between the coarse and fine fractions of the surface sands, with the finest <4 μm fraction enriched in Al 2O 3, Fe 2O 3, MnO, MgO and K 2O and the <32 μm fractions in Sc, Y, Th and the REE relative to the coarse fractions. The <4 μm fraction best represents the bulk REE <span class="hlt">geochemistry</span> of the samples. The provenance tracers Y/∑REE, La/Er, La/Gd, Gd/Er, La/Yb, Y/Tb, Y/La, Y/Nd and to a certain extent the europium anomaly Eu/Eu ∗ (all REE normalized to post-Archean Australian shale, PAAS) are particle size-independent tracers, of which combinations of Y/∑REE, La/Yb, Y/Tb, Y/La and Eu/Eu ∗ can be used to distinguish the Thar desert, the Chinese deserts, the Chinese loess plateau and the Tibetan soils. Their independence upon grain size means that these tracers can be applied to the long-range provenance tracing of Asian dust even when only bulk samples are available in the source region. Combinations of La/Th, Y/Tb, Y/∑REE, Sc/La and Y/Er distinguish the Tibetan soils from the Chinese loess plateau and the Chinese deserts. La/Th and notably Th/∑REE isolate the signature of the Badain Juran desert and the combination of Sc/La and Y/Er that of the Taklamakan desert. The similarity in all trace and REE-based provenance tracers between the northern Qaidam basin and Tengger desert suggests that these two deposits may have a common aeolian source.</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 Tulou, if rated by the LEED green building certification program, would earn the highest certification as this rammed <span class="hlt">earth</span> construction has offered efficient living for hundreds of years. As historic as these rammed <span class="hlt">earth</span> structures are, they present an environmentally friendly option to structures of the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.135..217R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.135..217R"><span id="translatedtitle">Dripwater organic matter and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> in a semi-arid karst environment: Implications for speleothem paleoclimatology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rutlidge, Helen; Baker, Andy; Marjo, Christopher E.; Andersen, Martin S.; Graham, Peter W.; Cuthbert, Mark O.; Rau, Gabriel C.; Roshan, Hamid; Markowska, Monika; Mariethoz, Gregoire; Jex, Catherine N.</p> <p>2014-06-01</p> <p>A series of four short-term infiltration experiments which revealed hydrochemical responses relevant to semi-arid karst environments were carried out above Cathedral Cave, Wellington, New South Wales (NSW), Australia. Dripwater samples were collected at two sites for trace <span class="hlt">element</span> and organic matter analysis. Organic matter was characterised using fluorescence and interpreted using a PARAFAC model. Three components were isolated that represented unprocessed, soil-derived humic-like and fulvic-like material, processed humic/fulvic-like material and tryptophan-like fluorescence. Principal Component Analysis (PCA) performed on the entire dataset comprising trace <span class="hlt">element</span> concentrations and PARAFAC scores revealed two dominant components that were identified as soil and limestone bedrock. The soil component was assigned based on significant contributions from the PARAFAC scores and additionally included Ba, Cu, Ni and Mg. The bedrock component included the expected <span class="hlt">elements</span> of Ca, Mg and Sr as well as Si. The same <span class="hlt">elemental</span> behaviour was observed in recent stalagmite growth collected from the site. Our experiments demonstrate that existing paleoclimate interpretations of speleothem Mg and Sr, developed in regions of positive water balance, are not readily applicable to water limited environments. We provide a new interpretation of trace <span class="hlt">element</span> signatures unique to speleothems from water limited karst environments.</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> </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/1008833','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1008833"><span id="translatedtitle">The effect of rare <span class="hlt">earth</span> <span class="hlt">elements</span> on the texture and formability of asymmetrically rolled magnesium sheet</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Alderman, Dr. Martyn; Cavin, Odis Burl; Davis, Dr. Bruce; Muralidharan, Govindarajan; Muth, Thomas R; Peter, William H; Randman, David; Watkins, Thomas R</p> <p>2011-01-01</p> <p>The lack of formability is a serious issue when considering magnesium alloys for various applications. Standard symmetric rolling introduces a strong basal texture that decreases the formability; however, asymmetric rolling has been put forward as a possible route to produce sheet with weaker texture and greater ductility. It has also been shown in recent work that weaker textures can be produced through the addition of rare <span class="hlt">earth</span> <span class="hlt">elements</span> to magnesium alloys. Therefore, this study has been carried out to investigate the effect of rare <span class="hlt">earth</span> additions on the texture changes during asymmetric rolling. Two alloys have been used, AZ31B and ZEK100. The effect that the rare <span class="hlt">earth</span> additions have on the texture of asymmetrically rolled sheet and the subsequent changes in formability will be discussed.</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 ?m-size phosphates, which have high LaN/LuN ratios and negative Eu anomalies. Terrestrial rocks and samples from ordinary and enstatite chondrites display negative Tm anomalies of ?-4.5% relative to CI chondrites. In contrast, CM, CO and CV (except Allende) show no significant Tm anomalies. Allende CV chondrite shows large excess Tm (?+10%). These anomalies are similar to those found in group II refractory inclusions in meteorites but of much smaller magnitude. The presence of Tm anomalies in meteorites and terrestrial rocks suggests that either (i) the material in the inner part of the solar system was formed from a gas reservoir that had been depleted in refractory dust and carried positive Tm anomalies or (ii) CI chondrites are enriched in refractory dust and are not representative of solar composition for refractory <span class="hlt">elements</span>. A new reference composition relevant to inner solar system bodies (CI?) is calculated by subtracting 0.15% of group II refractory inclusions to CI. The observed Tm anomalies in ordinary and enstatite chondrites and terrestrial rocks, relative to carbonaceous chondrites, indicate that material akin to carbonaceous chondrites must have represented a small fraction of the constituents of the <span class="hlt">Earth</span>. Tm anomalies may be correlated with Ca isotopic fractionation in bulk planetary materials as they are both controlled by addition or removal of refractory material akin to fine-grained group II refractory inclusions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5630347','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5630347"><span id="translatedtitle">Separation of tervalent transplutonium and rare-<span class="hlt">earth</span> <span class="hlt">elements</span> using for-tveks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zaitsev, B.N.; Korolev, V.A.; Korovin, Y.F.; Kuzovov, Y.I.; Kvasnitskii, I.B.; Popik, V.P.</p> <p>1986-03-01</p> <p>The authors study the distribution of curium, americium, and certain rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) between aqueous nitric acid solutions and FOR-tveks under static and dynamic conditions. It is shown that on introducing diethylenetriaminepentaacetic acid into the aqueous solution separation coefficients for the transplutonium <span class="hlt">elements</span> and REE can be obtained which are sufficiently high for practical use. A method is proposed for the group separation of REE and transplutonium <span class="hlt">elements</span> under dynamic conditions. On a column 22 cm high coefficients of approximately 500 are obtained for the purification of curium from cerium, more than 260 from neodymium, 250 from lanthanum, and 14 from europium and gadolinium. The possibility has been studied of separating palladium from transplutonium <span class="hlt">elements</span> and REE and isolating it as an individual product.</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> <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://adsabs.harvard.edu/abs/1989RpScT...1...11B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989RpScT...1...11B"><span id="translatedtitle">Circular dust formations around <span class="hlt">earth</span> and moon and some structural <span class="hlt">elements</span> of dust formation around sun</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barsukov, V. L.; Nazarova, T. N.</p> <p>1989-01-01</p> <p>An analysis of meteoroid data from the Elektron 1 and 2, HEOS 2, Luna 10, Zond 3, and Venera 2 probes reveals the existence of circumterrestrial and circumlunar dust envelopes and yields information about the <span class="hlt">elements</span> of an analogous circumsolar dust envelope. It is shown that meteoritic matter in these envelopes is distributed not uniformly but as individual clusters which move along gravitation centers (the <span class="hlt">earth</span>, the moon, and the sun) in more or less stable orbits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P44A..05V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P44A..05V"><span id="translatedtitle">Selenium isotopes indicate a chondritic origin of volatile <span class="hlt">elements</span> on <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>Vollstaedt, H.; Mezger, K.; Leya, I.</p> <p>2014-12-01</p> <p>For a planet to provide conditions that are conducive for the origin and evolution of life, it is required to host liquid water and other volatile <span class="hlt">elements</span> and compounds. The details of the planet forming processes starting from the condensation of matter in the solar nebula to the accretion of planets are, however, still elusive. Specifically, how planets like Venus, <span class="hlt">Earth</span>, and Mars acquired their volatile <span class="hlt">element</span> content, although they formed so close to the Sun and inside the snowline of the early solar system is a matter of the current scientific debate. To constrain the origin and addition of moderately to highly volatile components to the rocky planets of the inner solar system we studied the variation of the isotopes of the highly volatile, chalcophile, and siderophile <span class="hlt">element</span> selenium (Se) and its abundance in different early solar system materials, planetesimals, and planets. Selenium is depleted within the Silicate <span class="hlt">Earth</span> relative to CI , but in chondritic-relative abundance to siderophile <span class="hlt">elements</span> like S and Te (Wang and Becker, 2013). The latter might reflect the accretion of a chondritic 'late veneer' after core formation which might also be the dominant source of water and carbon. The Se isotope composition (?82/76Se) of ordinary and iron meteorites and a terrestrial sample (Green River Shale, SGR-1, USGS) were found to be identical within the measurement uncertainty. If the depletion of volatile <span class="hlt">elements</span> on <span class="hlt">Earth</span> were exclusively caused by removal during core formation and/or evaporation during planet formation, a strongly Se-depleted and isotopically fractionated silicate reservoir would be expected. The relatively uniform ?82/76Se values between different groups of meteorites and the terrestrial value point to a later addition of volatiles to <span class="hlt">Earth</span> from a source that contained unfractionated Se isotopes and thus originates most likely from a region within the solar system where the volatile <span class="hlt">elements</span> and compounds condensed quantitatively. Wang, Z., Becker, H., 2013. Ratios of S, Se and Te in the silicate <span class="hlt">Earth</span> require a volatile-rich late veneer. Nature 499, 328-331.</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/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/2012EGUGA..14.6184C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.6184C"><span id="translatedtitle">The early Aptian OAE record in the Cau section (Prebetic Zone, Spain): High-resolution C-isotope stratigraphy, biomarker distributions, and <span class="hlt">elemental</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>Castro, J. M.; Quijano, M. L.; de Gea, G. A.; Pancost, R. D.</p> <p>2012-04-01</p> <p>The occurrence of time intervals of enhanced deposition of organic matter (OM) during the Cretaceous, defined as Oceanic Anoxic Events (OAE), reflect abrupt changes in global carbon cycling. These episodes raise questions about the causes for such perturbations, and their relation to fluctuations in ocean <span class="hlt">geochemistry</span>, climate, and marine and continental biota. To investigate these questions, we have performed an integrated study comprising high-resolution C-isotope stratigraphy, biomarker distributions, and <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> through the record of an expanded section of the OAE 1a (Cau section, Spain). This section belongs to the Prebetic Zone, which represents the platform domain of the Southern Iberian Paleomargin during the Mesozoic. The high-resolution C-isotope curve records the characteristic first negative and subsequent positive excursions that are well known from a large number of sections around the world. Apparent in the section are all eight of the segments previously defined from the alpine domain by Menegatti et al (1998). Both carbonate and organic C-isotope curves are presented and compared, allowing qualitative consideration for changes in pCO2. Molecular analyses of sedimentary organic matter are powerful tools in assessing the origin of organic matter and constraining ancient environmental conditions, such as marine productivity, anoxia in bottom waters or the photic zone and sea surface temperatures as well as its thermal maturity. The biomarker association in the section comprises mainly four main groups of compounds: n-alkanes, isoprenoids, hopanes and steranes. Overall, all of the OM present in the studied samples is interpreted to derive from significant terrestrial inputs as well as marine and bacterial sources. It is also thermally immature, leading to a good preservation of the organic compounds. This study has revealed major variations in biomarker distributions through the section, including the distributions of n-alkanes (long-chain versus short-chain compounds), relative abundances of n-alkanes, hopanes and steranes, and other significant biomarkers. These changes are interpreted to be related to variations in the major sources of the organic matter (bacterial, terrestrial and marine plants, marine plankton), and in the environmental conditions (i.e. development of water column stratification, anoxia and productivity). <span class="hlt">Elemental</span> geochemical analyses have revealed major changes in redox-sensitive, productivity and provenance proxies through the section. The main contribution from these data is the observation of development of suboxic-anoxic conditions during the deposition of the OAE1a, with high frequency oscillations, especially during the onset of the event. Integration of C-isotopes, biomarkers and <span class="hlt">elemental</span> distributions represents a powerful tool in the interpretation of the environmental changes that occurred during deposition of the OAE1a. Data presented here suggest significant sedimentary and biological perturbations predating the OAE1a, and environmental instability during especially the first stages of the OAE. Acknowledgements: This work is a contribution of the research project CGL2009-10329.</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://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://adsabs.harvard.edu/abs/2011AGUFM.P14A..02S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.P14A..02S"><span id="translatedtitle">Heterogeneous Accretion of the <span class="hlt">Earth</span> and the Timing of Volatile <span class="hlt">Element</span> Depletion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schönbächler, M.; Nimmo, F.</p> <p>2011-12-01</p> <p>The <span class="hlt">Earth</span> is depleted in moderately volatile <span class="hlt">elements</span> relative to CI chondrites and thus average solar system material. The timing of this depletion has been a matter of debate. Isotopic constraints from the short-lived Pd-Ag, Mn-Cr and Hf-W decay systems can be used to model the accretion history of the <span class="hlt">Earth</span> and the timing of moderately volatile <span class="hlt">element</span> depletion [1]. While the Pd-Ag decay system provides evidence for the accretion of volatile-rich material, other systems like Mn-Cr and Rb-Sr require that the <span class="hlt">Earth</span> accreted volatile-depleted material [2, 3]. As recently shown [1], the contrasting evidence from these decay systems can be reconciled by heterogeneous accretion, which implies that the composition of the material from which the <span class="hlt">Earth</span> accreted changed over time. A continuous core formation model was used and the best match was obtained for the <span class="hlt">Earth</span> mainly accreting volatile-depleted material in the beginning and more volatile-rich material towards the end, while core formation was still ongoing [1]. However, a different study proposed that the bulk of the moderately volatile <span class="hlt">elements</span> was delivered in a volatile-rich late veneer after core formation ceased [4]. This is not supported by the Pd-Ag data (Ag is a moderately volatile <span class="hlt">element</span>, while Pd is more refractory). A late veneer of volatile-rich CI material (Pd = 556 ppb and Ag = 197 ppb) after core formation is limited to a maximum of ~0.4 % of the <span class="hlt">Earth</span>'s mass by the Pd concentration of the <span class="hlt">Earth</span>'s mantle today (~3.3 ppb). This amount of CI material does not supply enough Ag to substantially modify the Ag isotope composition of the <span class="hlt">Earth</span>'s mantle. In a scenario where the <span class="hlt">Earth</span> accretes exceedingly volatile depleted material, its high Pd/Ag ratio would lead to an extreme radiogenic Ag isotope composition of the bulk silicate <span class="hlt">Earth</span> (BSE), which cannot be counterbalanced by the late veneer to match the observed BSE composition. We also tested the heterogeneous accretion scenario using N-body accretion simulations [5] for the Pd-Ag decay system. Again the best results were obtained when materials with different degrees of volatile depletion (= different Pd/Ag ratios) were accreted. The simulations include early accretion of close-in material and later accretion of material from greater heliocentric distances, which is consistent with a transition from volatile-depleted to volatile-enriched material. Therefore, N-body accretion simulations and the continuous core formation model yield similar results, which demonstrates the robustness of the heterogeneous accretion scenario. [1] Schönbächler et al. (2010), Science 328, 884. [2] Carlson & Lugmair (1988), <span class="hlt">Earth</span> Planet Sci. Lett. 90, 119. [3] Qin et al. (2009), Geochim. Cosmochim. Acta 74, 1122. [4] Albarède (2009), Nature, 461, 1227.[5] O'Brien et al. (2006), Icarus 184, 36.</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/2016MMTE..tmp....1R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MMTE..tmp....1R"><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>2016-01-01</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://ntrs.nasa.gov/search.jsp?R=19820048232&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820048232&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth"><span id="translatedtitle">Complementary rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns in unique achondrites, such as ALHA 77005 and shergottites, and in the <span class="hlt">earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ma, M.-S.; Schmitt, R. A.; Laul, J. C.</p> <p>1982-01-01</p> <p>Abundances of major, minor, and trace <span class="hlt">elements</span> are determined in the Antarctic achondrite Allan Hills (ALHA) 77005 via sequential instrumental and radiochemical neutron activation analysis. The rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) abundances of ALHA 77005 reveal a unique chondritic normalized pattern; that is, the REEs are nearly unfractionated from La to Pr at approximately 1.0X chondrites, monotonically increased from Pr to Gd at approximately 3.4X with no Eu anomaly, nearly unfractionated from Gd and Ho and monotonically decreased from Ho to Lu at approximately 2.2X. It is noted that this unique REE pattern of ALHA 77005 can be modeled by a melting process involving a continuous melting and progressive partial removal of melt from a light REE enriched source material. In a model of this type, ALHA 77005 could represent either a crystallized cumulate from such a melt or the residual source material. Calculations show that the parent liquids for the shergottites could also be derived from a light REE enriched source material similar to that for ALHA 77005.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C11B0358K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C11B0358K"><span 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/2014AGUFMDI23B4293L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMDI23B4293L"><span id="translatedtitle">What Can Neutrinos Tell Us about Light <span class="hlt">Elements</span> in <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>Li, J.; Dye, S.; Enomoto, S.</p> <p>2014-12-01</p> <p>The light <span class="hlt">element</span> composition of the <span class="hlt">Earth</span>'s core remains mysterious despite decades' of research. Without any direct samples, our knowledge of the core composition has relied on a diversity of constraints including the density and velocity profiles derived from seismic and geophysical observations, the composition models proposed on the basis of geochemical and cosmochemical measurements, the material properties determined by mineral physics investigations, and the thermal and dynamo requirements coming out of dynamic modeling. The leading candidates for the principal light <span class="hlt">element</span> include hydrogen, carbon, oxygen, sulfur and silicon, in the order of increasing atomic number. While each candidate stands out in some aspects and raises questions in others, none has been universally accepted as the dominant light <span class="hlt">element</span> in the core. The controversy arises partly because the properties and behavior of various iron-alloys at extreme pressure and temperature conditions have not been fully constrained. It is also conceivable that existing approaches will not produce unique solution, and therefore requires new strategies. Neutrino oscillation tomography has recently emerged as a promising technique to probe the composition of <span class="hlt">Earth</span>'s interior. Neutrinos are produced in the atmosphere by cosmic ray interactions. Atmospheric neutrinos pass through the <span class="hlt">Earth</span>'s mantle and core, with flavor oscillations being affected by the electron density of the medium along the trajectories. The unique sensitivity of the atmospheric neutrinos to electron density introduces a contrast between hydrogen, which has a higher electron density, and carbon, oxygen, sulfur, and silicon, which have lower and similar electron densities. With sufficient exposure to an appropriate energy range, atmospheric neutrino measurements may allow us to detect the presence of the core and measure its radius. Here we compare electron densities of candidate model compositions of <span class="hlt">Earth</span>'s core and estimate the exposure requirements for identifying the dominant light <span class="hlt">element</span> thorough neutrino oscillation tomography for both neutrino mass hierarchies. In particular, we will evaluate if any of the on-going and next-generation projects IceCube, PINGU, MICA, and HyperK can tell us about the light <span class="hlt">elements</span> in <span class="hlt">Earth</span>'s core.</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> </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://adsabs.harvard.edu/abs/2015EGUGA..17.3552S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.3552S"><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/abs/1990JVGR...44..123C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990JVGR...44..123C"><span id="translatedtitle">The 2 Ga peraluminous magmatism of the Jacobina Contendas Mirante Belt (Bahia) Brazil): Major and trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> and metallogenic potential</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuney, Michel; Sabat, Pierre; Vidal, Philippe; Marinho, Moacyr M.; Conceiao, Herbet</p> <p>1990-12-01</p> <p>The Jacobina Contendas Mirante belt represents a Transamazonian (2 Ga), N-S, 500-km long, elongated orogenic domain in the central part of the So Francisco craton, Bahia state. Numerous syntectonic to post-tectonic peraluminous leucogranites were emplaced along the major structures of the belt. Their mineralogical and geochemical and some of their metallogenetic characteristics are very similar to their Hercynian and Himalayan equivalents. However, their average peraluminous index varies from one granitic pluton to another and biotite is, on average, slightly more magnesian in the Transamazonian leucogranites. Higher oxygen fugacity is indicated by the general occurrence of magnetite, the stability of allanite and sometimes epidote in most of the plutons and by biotite chemistry. The peraluminous magmatism of the Jacobina-Contendas Mirante belt results from crustal partial melting during a continental collision event at 2 Ga. Trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> implies variable source composition and/or melting conditions for the different granitic plutons and some different facies within the same plutonic unit. The scarcity of ilmenite, the general occurrence of magnetite, and the relatively low peraluminous index of some of these granites suggest that graphite-beating sediments are not a significantly source material. From their mineralogical and geochemical characteristics, acid meta-igneous rocks such as the Sete Voltas TTG suite of presumed Archaean age, seem to represent a suitable source for these granites. Sn, W, Li, F and Be enrichment of most Transamazonian leucogranites is much weaker than in the mineralized Variscan equivalents. The Caetano-Aliana and Riacho das Pedras granites represent the most specialized granitic bodies. Beryl (emerald), molybdenite and scheelite mineralizations are related to some of these granites which intrude ultrabasic formations: the Campo Formoso and the Carnaiba granites. In many of these granites, uranium content is comparable to values measured in mineralized Hercynian leucogranites. The occurrence of hexavalent uranium minerals, mineralization and episyenitic alteration are favourable criteria for finding Variscan-type uranium ore deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790055121&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790055121&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Drare%2Bearth"><span id="translatedtitle">Experimental partitioning of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and scandium among armalcolite, ilmenite, olivine and mare basalt liquid</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Irving, A. J.; Merrill, R. B.; Singleton, D. E.</p> <p>1978-01-01</p> <p>An experimental study was carried out to measure partition coefficients for two rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (Sm and Tm) and Sc among armalcolite, ilmenite, olivine and liquid coexisting in a system modeled on high-Ti mare basalt 74275. This 'primitive' sample was chosen for study because its major and trace <span class="hlt">element</span> chemistry as well as its equilibrium phase relations at atmospheric pressure are known from previous studies. Beta-track analytical techniques were used so that partition coefficients could be measured in an environment whose bulk trace <span class="hlt">element</span> composition is similar to that of the natural basalt. Partition coefficients for Cr and Mn were determined in the same experiments by microprobe analysis. The only equilibrium partial melting model appears to be one in which ilmenite is initially present in the source region but is consumed by melting before segregation of the high-Ti mare basalt liquid from the residue.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23548400','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23548400"><span id="translatedtitle">Bioleaching of rare <span class="hlt">earth</span> and radioactive <span class="hlt">elements</span> from red mud using Penicillium tricolor RM-10.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qu, Yang; Lian, Bin</p> <p>2013-05-01</p> <p>The aim of this work is to investigate biological leaching of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and radioactive <span class="hlt">elements</span> from red mud, and to evaluate the radioactivity of the bioleached red mud used for construction materials. A filamentous, acid-producing fungi named RM-10, identified as Penicillium tricolor, is isolated from red mud. In our bioleaching experiments by using RM-10, a total concentration of 2% (w/v) red mud under one-step bioleaching process was generally found to give the maximum leaching ratios of the REEs and radioactive <span class="hlt">elements</span>. However, the highest extraction yields are achieved under two-step bioleaching process at 10% (w/v) pulp density. At pulp densities of 2% and 5% (w/v), red mud processed under both one- and two-step bioleaching can meet the radioactivity regulations in China. PMID:23548400</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992NIMPB..70...14B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992NIMPB..70...14B"><span id="translatedtitle">Separation method and yields of small quantities 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>Boulin, Y.; Juery, A.</p> <p>1992-08-01</p> <p>The EMIS PARSIFAL was designed to purify very small quantities of radioactive isotopes. Yields are therefore an important component of the separations. The ionization is done in a thermoionization source or a plasma source, according to the physical properties of the concerned <span class="hlt">elements</span>. For rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE), hydroxides are electrodeposited on a tantalum wire; for thermoionization, the wire is introduced in a tungsten crucible whose depth is linked to the boiling point of the <span class="hlt">element</span>. Samples weigh between 0.2 and 0.9 mg. The crucible, heated at 3050C by electron bombardment, gives REE yields from 20 to 40% and usually 50% for europium. The total beam intensity is about 5 10 -6 A and separations last from 2 to 20 hours until the whole sample is consumed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998EOSTr..79..356M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998EOSTr..79..356M"><span id="translatedtitle">Principles and Applications of <span class="hlt">Geochemistry</span>, 2nd Edition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marcantonio, Franco</p> <p></p> <p>Many academic geology departments do not include <span class="hlt">geochemistry</span> in their undergraduate core curriculums. The second edition of Principles and Applications of <span class="hlt">Geochemistry</span> demonstrates why this should change. Gunter Faure's book clearly shows the important role played by quantitative geochemical analysis in our understanding of <span class="hlt">Earth</span> processes, both natural and anthropogenic. Intended as an introductory inorganic <span class="hlt">geochemistry</span> text for senior undergraduates or first-year graduate students, the book makes even the most difficult concepts readily understandable. Beyond its lucid technical explanations, it also includes engaging discussions of the history of <span class="hlt">geochemistry</span> as a science.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19001263','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19001263"><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=pubmed">PubMed</a></p> <p>Ozima, Minoru; Yin, Qing-Zhu; Podosek, Frank A; Miura, Yayoi N</p> <p>2008-11-18</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 <span class="hlt">Earth</span>-Moon dynamical system. PMID:19001263</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.; Dupr, 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://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 compositions in the interplinian rocks show a tendency to become slightly more radiogenic with age, from the Protohistoric (143Nd/144Nd=0.51240-0.51247) to Ancient Historic (143Nd/144Nd=0.51245-0.51251). Medieval interplinian activity (143Nd/144Nd: 0.51250-0.51241) lacks meaningful internal trends. All the interplinian rocks have virtually homogeneous compositions of 207Pb/204Pb and 208Pb/204Pb in acid-leached residues (207Pb/204Pb ???15.633 to 15.687, 208Pb/204Pb ???38.947 to 39.181). Values of 206Pb/204Pb are very distinctive, however, and discriminate among the three interplinian cycles of activity (Protohistoric: 18.929-18.971, Ancient Historic: 19.018-19.088, Medieval: 18.964-19.053). Compositional trends of major, trace <span class="hlt">element</span> and isotopic compositions clearly demonstrate strong temporal variations of the magma types feeding the Somma-Vesuvius activity. These different trends are unlikely to be related only to low pressure evolutionary processes, and reveal variations of parental melt composition. Geochemical data suggest a three component mixing scheme for the interplinian activity. These involve HIMU-type and DMM-type mantle and Calabrian-type lower crust. Interaction between these components has taken place in the source; however, additional quantitative constraints must be acquired in order to better discriminate between magma characteristics inherited from the sources and those acquired during shallow level evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.V23G..07D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.V23G..07D"><span id="translatedtitle">Dynamical <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>Davies, G. F.</p> <p>2009-12-01</p> <p>Dynamical and chemical interpretations of the mantle have hitherto remained incompatible, despite substantial progress over recent years. It is argued that both the refractory incompatible <span class="hlt">elements</span> and the noble gases can be reconciled with the dynamical mantle when mantle heterogeneity is more fully accounted for. It is argued that the incompatible-<span class="hlt">element</span> content of the MORB source is about double recent estimates (U~10 ng/g) because enriched components have been systematically overlooked, for three main reasons. (1) in a heterogeneous MORB source, melts from enriched pods are not expected to equilibrate fully with the peridotite matrix, but recent estimates of MORB-source composition have been tied to residual (relatively infertile) peridotite composition. (2) about 25% of the MORB source comes from plumes, but plume-like components have tended to be excluded. (3) a focus on the most common “normal” MORBs, allegedly representing a “depleted” MORB source, has overlooked the less-common but significant enriched components of MORBs, of various possible origins. Geophysical constraints (seismological and topographic) exclude mantle layering except for the thin D” layer and the “superpiles” under Africa and the Pacific. Numerical models then indicate the MORB source comprises the rest of the mantle. Refractory-<span class="hlt">element</span> mass balances can then be accommodated by a MORB source depleted by only a factor of 2 from chondritic abundances, rather than a factor of 4-7. A source for the hitherto-enigmatic unradiogenic helium in OIBs also emerges from this picture. Melt from subducted oceanic crust melting under MORs will react with surrounding peridotite to form intemediate compositions here termed hybrid pyroxenite. Only about half of the hybrid pyroxenite will be remelted, extracted and degassed at MORs, and the rest will recirculate within the mantle. Over successive generations starting early in <span class="hlt">Earth</span> history, volatiles will come to reside mainly in the hybrid pyroxenite. This will be denser than average mantle and will tend to accumulate in D”, like subducted oceanic crust. Because residence times in D” are longer, it will degas more slowly. Thus plumes will tap a mixture of older, less-degassed hybrid pyroxenite, containing less-radiogenic noble gases, and degassed former oceanic crust. Calculations of degassing history confirm that this picture can quantitatively account for He, Ne and Ar in MORBs and OIBs. Geophysically-based dynamical models have been shown over recent years to account quantitatively for the isotopes of refractory incompatible <span class="hlt">elements</span>. This can now be extended to noble gas isotopes. The remaining significant issue is that thermal evolution calculations require more radiogenic heating than implied by cosmochemical estimates of radioactive heat sources. This may imply that tectonic and thermal evolution have been more episodic in the Phanerozoic than has been generally recognised.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980CoMP...73..375C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980CoMP...73..375C"><span id="translatedtitle"><span class="hlt">Geochemistry</span> and petrogenesis of late proterozoic volcanic rocks from north-western Africa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chikhaoui, M.; Dupuy, C.; Dostal, J.</p> <p>1980-09-01</p> <p>The Upper Proterozoic volcanism of northwestern Africa is characterized by the predominance of calc-alkaline rocks. Volcanics with tholeiitic affinities and alkali basalts are rare. The <span class="hlt">geochemistry</span> and the relative proportions of calc-alkaline rocktypes in the Silet zone (Algeria) and the Ouarzazate formation (Morocco) are similar to those of recent island arc suites where basalts are most abundant while in the Tassendjanet and Gara Akofo zones (Algeria) they resemble contintal margin volcanic suites with a predominance of andesites. The volcanic rocks have undergone low-grade metamorphism which strongly affected alkali and alkali-<span class="hlt">earth</span> <span class="hlt">elements</span> and also to a smaller degree, the less mobile <span class="hlt">elements</span> such as REE, Zr, Hf, Nb, and P. The <span class="hlt">geochemistry</span> of the calc-alkaline rocks point to a complex origin involving low-pressure fractional crystallization, crustal contamination and derivation from a source already enriched in LILE.</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> <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://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://adsabs.harvard.edu/abs/2015SPIE.9482E..0GM','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9482E..0GM"><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.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://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.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.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://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 Mara 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 (?13C and ?18O) 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, suggesting early agricultural activity in the area, being the first record of maize in the western region of Mesoamerica. The phases with higher concentration of Ti are identified as periods of higher inflow into the lake basin (BC 1700-1400, 0- AD 200, AD 900 and AD 1800-1900). Phases of higher evaporative conditions are identify at ca. BC 700, BC 400, AD 400-800 and AD 1900-2003 based on Ca high values and enriched ?18O and ?13C. There exists a negative relationship between Ca and Ti. Evidence of changes in climatic conditions is inferred from the data.</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/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 ?Nd (-7.9 to -3.3) and zircon ?Hf (-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 window may have facilitated partial melting of the subducted oceanic lithosphere and the lower crust.</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; Valena, Manuela; Cascalho, Joo; Pereira, Eduarda; Lilleb, 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 (38N-29N) 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://ntrs.nasa.gov/search.jsp?R=19850010583&hterms=earths+plates&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dearths%2Bplates','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850010583&hterms=earths+plates&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dearths%2Bplates"><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://www.osti.gov/scitech/biblio/285526','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/285526"><span id="translatedtitle">The chemistry of the light rare-<span class="hlt">earth</span> <span class="hlt">elements</span> as determined by electron energy loss spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fortner, J.A.; Buck, E.C.</p> <p>1996-06-01</p> <p>The energy loss spectra of the rare <span class="hlt">earths</span> are characterized by sharp {ital M}{sub 4,5} edges, the relative intensities of which are characteristic of the 4{ital f}-shell occupancy of the excited ion. For the light rare <span class="hlt">earths</span>, the dependence of these relative peak heights on 4{ital f}-shell occupancy is quite pronounced. Thus they may be used to determine the oxidation state of the multivalent <span class="hlt">elements</span> Ce and Pr. The second derivative of the spectrum is shown to be extremely sensitive to the chemical environment. Modern instrumentation and detection techniques allow the oxidation state of Ce and Pr to be determined even when they are present as only minor constituents. {copyright} {ital 1996 American Institute of Physics.}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GGG....13.1020H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GGG....13.1020H"><span id="translatedtitle">Online preconcentration ICP-MS analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in seawater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hathorne, Ed C.; Haley, Brian; Stichel, Torben; Grasse, Patricia; Zieringer, Moritz; Frank, Martin</p> <p>2012-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) with their systematically varying properties are powerful tracers of continental inputs, particle scavenging intensity and the oxidation state of seawater. However, their generally low (pmol/kg) concentrations in seawater and fractionation potential during chemical treatment makes them difficult to measure. Here we report a technique using an automated preconcentration system, which efficiently separates seawater matrix <span class="hlt">elements</span> and elutes the preconcentrated sample directly into the spray chamber of an ICP-MS instrument. The commercially available "seaFAST" system (<span class="hlt">Elemental</span> Scientific Inc.) makes use of a resin with ethylenediaminetriacetic acid and iminodiacetic acid functional groups to preconcentrate REEs and other metals while anions and alkali and alkaline <span class="hlt">earth</span> cations are washed out. Repeated measurements of seawater from 2000 m water depth in the Southern Ocean allows the external precision (2?) of the technique to be estimated at <23% for all REEs and <15% for most. Comparison of Nd concentrations with isotope dilution measurements for 69 samples demonstrates that the two techniques generally agree within 15%. Accuracy was found to be good for all REEs by using a five point standard addition analysis of one sample and comparing measurements of mine water reference materials diluted with a NaCl matrix with recommended values in the literature. This makes the online preconcentration ICP-MS technique advantageous for the minimal sample preparation required and the relatively small sample volume consumed (7 mL) thus enabling large data sets for the REEs in seawater to be rapidly acquired.</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://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://adsabs.harvard.edu/abs/2011GeCoA..75.1451S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeCoA..75.1451S"><span id="translatedtitle">Systematics of metal-silicate partitioning for many siderophile <span class="hlt">elements</span> applied to <span class="hlt">Earths</span> core formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siebert, Julien; Corgne, Alexandre; Ryerson, Frederick J.</p> <p>2011-03-01</p> <p>Superliquidus metal-silicate partitioning was investigated for a number of moderately siderophile (Mo, As, Ge, W, P, Ni, Co), slightly siderophile (Zn, Ga, Mn, V, Cr) and refractory lithophile (Nb, Ta) <span class="hlt">elements</span>. To provide independent constrains on the effects of temperature, oxygen fugacity and silicate melt composition, isobaric (3 GPa) experiments were conducted in piston cylinder apparatus at temperature between 1600 and 2600 C, relative oxygen fugacities of IW-1.5 to IW-3.5, and for silicate melt compositions ranging from basalt to peridotite. The effect of pressure was investigated through a combination of piston cylinder and multi-anvil isothermal experiments between 0.5 and 18 GPa at 1900 C. Oxidation states of siderophile <span class="hlt">elements</span> in the silicate melt as well as effect of carbon saturation on partitioning are also derived from these results. For some <span class="hlt">elements</span> (e.g. Ga, Ge, W, V, Zn) the observed temperature dependence does not define trends parallel to those modeled using metal-metal oxide free energy data. We correct partitioning data for solute interactions in the metallic liquid and provide a parameterization utilized in extrapolating these results to the P- T- X conditions proposed by various core formation models. A single-stage core formation model reproduces the mantle abundances of several siderophile <span class="hlt">elements</span> (Ni, Co, Cr, Mn, Mo, W, Zn) for core-mantle equilibration at pressures from 32 to 42 GPa along the solidus of a deep peridotitic magma ocean (3000 K for this pressure range) and oxygen fugacities relevant to the FeO content of the present-day mantle. However, these P- T- fO 2 conditions cannot produce the observed concentrations of Ga, Ge, V, Nb, As and P. For more reducing conditions, the P- T solution domain for single stage core formation occurs at subsolidus conditions and still cannot account for the abundances of Ge, Nb and P. Continuous core formation at the base of a magma ocean at P- T conditions constrained by the peridotite liquidus and fixed fO 2 yields concentrations matching observed values for Ni, Co, Cr, Zn, Mn and W but underestimates the core/mantle partitioning observed for other <span class="hlt">elements</span>, notably V, which can be reconciled if accretion began under reducing conditions with progressive oxidation to fO 2 conditions consistent with the current concentration of FeO in the mantle as proposed by Wade and Wood (2005). However, neither oxygen fugacity path is capable of accounting for the depletions of Ga and Ge in the <span class="hlt">Earth</span>'s mantle. To better understand core formation, we need further tests integrating the currently poorly-known effects of light <span class="hlt">elements</span> and more complex conditions of accretion and differentiation such as giant impacts and incomplete equilibration.</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://www.ncbi.nlm.nih.gov/pubmed/19757452','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19757452"><span id="translatedtitle">Determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in tomato plants by inductively coupled plasma mass spectrometry techniques.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Spalla, S; Baffi, C; Barbante, C; Turetta, C; Turretta, C; Cozzi, G; Beone, G M; Bettinelli, M</p> <p>2009-10-30</p> <p>In recent years identification of the geographical origin of food has grown more important as consumers have become interested in knowing the provenance of the food that they purchase and eat. Certification schemes and labels have thus been developed to protect consumers and genuine producers from the improper use of popular brand names or renowned geographical origins. As the tomato is one of the major components of what is considered to be the healthy Mediterranean diet, it is important to be able to determine the geographical origin of tomatoes and tomato-based products such as tomato sauce. The aim of this work is to develop an analytical method to determine rare <span class="hlt">earth</span> <span class="hlt">elements</span> (RRE) for the control of the geographic origin of tomatoes. The content of REE in tomato plant samples collected from an agricultural area in Piacenza, Italy, was determined, using four different digestion procedures with and without HF. Microwave dissolution with HNO3 + H2O2 proved to be the most suitable digestion procedure. Inductively coupled plasma quadrupole mass spectrometry (ICPQMS) and inductively coupled plasma sector field plasma mass spectrometry (ICPSFMS) instruments, both coupled with a desolvation system, were used to determine the REE in tomato plants in two different laboratories. A matched calibration curve method was used for the quantification of the analytes. The detection limits (MDLs) of the method ranged from 0.03 ng g(-1) for Ho, Tm, and Lu to 2 ng g(-1) for La and Ce. The precision, in terms of relative standard deviation on six replicates, was good, with values ranging, on average, from 6.0% for LREE (light rare <span class="hlt">earth</span> <span class="hlt">elements</span>) to 16.5% for HREE (heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span>). These detection limits allowed the determination of the very low concentrations of REE present in tomato berries. For the concentrations of REE in tomato plants, the following trend was observed: roots > leaves > stems > berries. PMID:19757452</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://adsabs.harvard.edu/abs/2005GGG.....6.4J15S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005GGG.....6.4J15S"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of serpentinized peridotites from the Mariana Forearc Conical Seamount, ODP Leg 125: Implications for the <span class="hlt">elemental</span> recycling at subduction zones</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Savov, Ivan P.; Ryan, Jeffrey G.; D'Antonio, Massimo; Kelley, Katherine; Mattie, Patrick</p> <p>2005-04-01</p> <p>Recent examinations of the chemical fluxes through convergent plate margins suggest the existence of significant mass imbalances for many key species: only 20-30% of the to-the-trench inventory of large-ion lithophile <span class="hlt">elements</span> (LILE) can be accounted for by the magmatic outputs of volcanic arcs. Active serpentinite mud volcanism in the shallow forearc region of the Mariana convergent margin presents a unique opportunity to study a new outflux: the products of shallow-level exchanges between the upper mantle and slab-derived fluids. ODP Leg 125 recovered serpentinized harzburgites and dunites from three sites on the crests and flanks of the active Conical Seamount. These serpentinites have U-shaped rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns, resembling those of boninites. U, Th, and the high field strength <span class="hlt">elements</span> (HFSE) are highly depleted and vary in concentration by up to 2 orders of magnitude. The low U contents and positive Eu anomalies indicate that fluids from the subducting Pacific slab were probably reducing in nature. On the basis of substantial enrichments of fluid-mobile <span class="hlt">elements</span> in serpentinized peridotites, we calculated very large slab inventory depletions of B (79%), Cs (32%), Li (18%), As (17%), and Sb (12%). Such highly enriched serpentinized peridotites dragged down to depths of arc magma generation may represent an unexplored reservoir that could help balance the input-output deficit of these <span class="hlt">elements</span> as observed by Plank and Langmuir (1993, 1998) and others. Surprisingly, many species thought to be mobile in fluids, such as U, Ba, Rb, and to a lesser extent Sr and Pb, are not enriched in the rocks relative to the depleted mantle peridotites, and we estimate that only 1-2% of these <span class="hlt">elements</span> leave the subducting slabs at depths of 10 to 40 km. Enrichments of these <span class="hlt">elements</span> in volcanic front and behind-the-front arc lavas point to changes in slab fluid composition at greater depths.</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://adsabs.harvard.edu/abs/1984Litho..17..259B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984Litho..17..259B"><span id="translatedtitle">Correlations between microstructures, K-feldspar triclinicity and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> in stanniferous and barren granites, northern Nigeria</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Badejoko, T. A.</p> <p></p> <p>The biotite granites in the Nigerian Younger Granites are a major source of the economic metals Sn, Nb, Zn and W. The textural variations in these rocks are considered together with the composition and structural state of the K-feldspars. The curious disparity in the degree of mineralization of these rocks of similar mineral assemblage is considered to be related to the textural and structural variations. The stanniferous granites are characterized by medium- to fine-grained texture, miarolitic cavities, subsolidus crystallization of biotite and albite; turbidity, coarsening and incoherent perthitic texture of the K-feldspar. The barren granites are usually coarse-grained with few druses, silvery irridescent feldspar grains and coherent perthitic texture. K-feldspars in the stanniferous granites are mainly of maximum microcline structure while the barren ones are characterized by intermediate microcline structure. Compositionally, all the K-feldspars have less than 3% An; they have crystallized in the binary system at temperatures close to 700C but have now re-equilibrated to various lower temperatures as a result of variable rock-fluid interaction. Positive correlations are observed between Nb, Sn, Rb, Li and F in granites and triclinicity of their K-feldspars. Enhancement of Rb-values is observed in both the stanniferous rocks and their K-feldspar constituents. The variable textures, degree of Al, Si order in the feldspars and enrichment in ore and trace <span class="hlt">elements</span> are attributed to the presence and abundance of a fluid phase. It is suggested that in the course of magmatic evolution of these rocks an alkali-rich volatile phase developed, accumulated and was trapped in the roof zone of the stanniferous granites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFMPP11B0308R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFMPP11B0308R"><span id="translatedtitle">Black Body Temperature in Terms of <span class="hlt">Earth</span>'s Orbital <span class="hlt">Elements</span> and the Milankovitch Precession Index</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rubincam, D. P.</p> <p>2002-12-01</p> <p>The temperature T of a black or gray body orbiting the Sun can be expressed in terms of spherical harmonics in latitude and longitude, its Keplerian orbital <span class="hlt">elements</span>, and a variable describing rotation about its axis. Assuming that the <span class="hlt">Earth</span> is a gray body, the resulting equation for T exhibits previously unrecognized odd-degree zonal terms dubbed "Seversmith psychroterms." They cause a hemispheric temperature gradient which depends upon e sin w, where e is the orbital eccentricity and w is the Sun's argument of perihelion measured in an <span class="hlt">Earth</span>-centered frame. The hemisphere containing perihelion is the cooler. For a gray body with the <span class="hlt">Earth</span>'s average albedo of 0.3, an emissivity of unity, and an obliquity of 23.5 degrees, the pole-to-pole temperature difference for the combined first and third degree spherical harmonic psychroterms can reach 3.4 K for the present eccentricity of 0.016, and 12.9 K for the maximum eccentricity of 0.06. While a black body with its boiling hot subsolar point and nights at absolute zero is a poor model for the <span class="hlt">Earth</span>, the Seversmith psychroterms survive in more realistic models (although with smaller amplitudes) because the <span class="hlt">Earth</span> radiates nonlinearly in T. The psychroterms acts in the direction opposite to the Milankovitch precession index, which also depends on e sin w: by warming the cool northern summers, the psychroterms make it harder for the traditional Milankovitch mechanism to operate. It may in fact be the Seversmith psychroterms which are actually responsible for the ice sheets which cycle with e sin w, instead of the Milankovitch mechanism. By cooling the southern hemisphere when perihelion is in the south, the psychroterms may somehow cause the southern hemisphere to control the northern ice sheets associated with the 19 kyr and 23 kyr periods (kyr = kiloyear), possibly through ice-albedo feedback in the sea-ice surrounding Antarctica.</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/2002NIMPB.189..459W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002NIMPB.189..459W"><span id="translatedtitle">Studies of rare <span class="hlt">earth</span> <span class="hlt">element</span> distribution and action in human erythrocyte and animal hepatocyte by PIXE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Y. P.; Mi, Y.; Shen, H.; Yao, H. Y.; Cheng, Y.; Wang, X.; Zhang, J. X.</p> <p>2002-04-01</p> <p>PIXE analysis is applied to investigate a long-term disputed issue whether the rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) can enter the cell across the cell membrane or not. It has been illustrated that REE could travel across the biomembrane into the cells by cell studies in vitro as well as in studies of animals fed with REEs diet. The binding of REE by membrane changes its permeability and makes intracellular ion transportable. Entrance of REEs may influence the cellular function. In addition, the REE distribution and behavior in cell are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://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 with unpublished whole-rock data for the 1986–1990 eruptive interval (episode 48, see Heliker and Mattox, 2003). The geochemical data in this report is mostly limited to well-quenched samples collected at or near their respective vents. The samples include tephra and spatter, in addition to lava dipped from lava lakes, lava tubes, and surface lava flows. The details of sample collection techniques as described by Thornber and others (2002) are generally applicable for this entire sampling interval. Specifically excluded from this database are samples of distal surface flows, many of which were collected for topical studies of emplacement dynamics (for example, Cashman and others, 1999). Samples of sluggish or crystal-laden tube flows collected during eruptive pauses were also excluded, because they bear visual, petrographic and geochemical evidence for crystal accumulation during surface-flow stagnation. In addition, the pre-1992 whole-rock major <span class="hlt">element</span> data reported here has been corrected to compensate for minor analytical discrepancies between pre- and post-1991 XRF analyses. These discrepancies resulted from a change in instrumentation at the USGS Denver analytical laboratories. This select suite of time-constrained geochemical data is suitable for constructing petrologic models of pre-eruptive magmatic processes associated with prolong rift zone eruption of Hawaiian shield volcanoes.</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-?-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; Sillanp, 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 ?-cyclodextrin (EDTA-?-CD) biopolymer was prepared and employed in adsorption of aqueous REEs, such as La(III), Ce(III), and Eu(III). EDTA acts not only as cross-linker but also as coordination site for binding of REEs. The adsorption properties for the adsorption of REEs by varying experimental conditions were carried out by batch tests. The kinetics results revealed that the surface chemical sorption and the external film diffusion were the rate-determining steps of the adsorption process. The obtained maximum adsorption capacities of EDTA-?-CD were 0.343, 0.353, and 0.365mmolg(-1) for La(III), Ce(III) and Eu(III), respectively. Importantly, the isotherms fitted better to Langmuir than Freundlich and Sips models, suggesting a homogenous adsorption surface for REEs on the adsorbent. Moreover, the multi-component adsorption, which was modeled by extended Sips isotherms, revealed adsorbent's selectivity to Eu(III). More significantly, the successful recoveries of the studied ions from tap water and seawater samples makes EDTA-?-CD a promising sorbent for the preconcentration of REEs from diluted aqueous streams. PMID:26674238</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JHyd..533..403Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JHyd..533..403Y"><span id="translatedtitle">Three dimensional analysis of unconfined seepage in <span class="hlt">earth</span> dams by the weak form quadrature <span class="hlt">element</span> method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yuan, Shuai; Zhong, Hongzhi</p> <p>2016-02-01</p> <p>It remains challenging to determine the unknown free surface in three dimensional unconfined seepage in <span class="hlt">earth</span> dams. A number of iterations are frequently required which make the problem computationally expensive. In the present research, a weak form quadrature <span class="hlt">element</span> formulation is presented for three dimensional analysis of unconfined seepage which is an extension of the recently established method for two dimensional seepage problems. "Free points" are introduced by the interpolation of which the free surfaces are smoothly approximated. Grid lines are constructed in the <span class="hlt">element</span> and the "free points" are confined to the lines when updated. An interpolatory scheme for locating the exit points is proposed. Formulations and procedures of the method are given in detail. Results of numerical examples are compared with available analytical solutions and numerical solutions in the literature and agreement is reached demonstrating the efficiency and reliability of the present formulation.</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/2015IJMMM..22..453L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IJMMM..22..453L"><span id="translatedtitle">Application of rare-<span class="hlt">earth</span> <span class="hlt">element</span> Y in refining impure copper</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Hai-hong; Sun, Xue-qin; Zhang, Shang-zhou; Zhao, Qin-yi; Wang, Guang-zhen</p> <p>2015-05-01</p> <p>The effects of rare-<span class="hlt">earth</span> <span class="hlt">element</span> Y in refining impure copper were investigated in this paper. The composition, microstructures, and corrosion resistance properties of impure copper before and after refinement with Y were investigated using direct-reading spectrometry, inductively coupled plasma atomic emission spectrometry, optical microscopy, scanning electron microscopy, and potentiodynamic polarization measurements. The results show that the concentrations of impurities S, As, Sb, Bi, Al, Cd, and Se are remarkably decreased. Adding an appropriate amount of Y refines the microstructure and enhances the corrosion resistance properties of impure copper in HCl solution via a purification effect. The formation enthalpies of compounds formed between Y and various impurity <span class="hlt">elements</span> were calculated on the basis of Miedema's theory. The thermodynamic mechanisms of the refinement of impure copper by Y were also discussed</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 observed in the shergottite pyroxenes is only consistent with degassing of LLE from a Martian melt near its liquidus temperature if the vapor-melt partition coefficient was an order of magnitude larger than observed on <span class="hlt">Earth</span>. The range in LLE and trace <span class="hlt">elements</span> observed in shergottite pyroxenes are instead consistent with concurrent mixing and fractionation of heterogeneous melts from the mantle.</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://adsabs.harvard.edu/abs/2000GeoJI.142..117M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000GeoJI.142..117M"><span id="translatedtitle">Spectral-finite <span class="hlt">element</span> approach to three-dimensional viscoelastic relaxation in 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>Martinec, Zden?k.</p> <p>2000-07-01</p> <p>We present a spectral-finite <span class="hlt">element</span> approach to the forward modelling of the visco-elastic response of a spherical <span class="hlt">earth</span> with a 3-D viscosity structure to a surface mass load. It represents an alternative to a variety of numerical methods for 2-D and 3-D postglacial rebound modelling used recently (the finite <span class="hlt">element</span> method, the perturbation method, the semi-analytical approach and the spectral-finite difference method). For a fixed time, the problem is reformulated in a weak sense and parametrized by tensor surface spherical harmonics in the angular direction, whereas piecewise linear finite <span class="hlt">elements</span> span the radial direction. The solution is obtained with the Galerkin method, which leads to solving a system of linear algebraic equations. The time dependence of the problem is treated directly in the time domain (not in the Laplace domain) as a time evolution problem. The time derivative in the constitutive equation for a Maxwell viscoelastic body is approximated by the explicit Euler time-differencing scheme, which leads to time splitting of the stress tensor. The spectral-finite <span class="hlt">element</span> method and the associated numerical code have been tested for 2-D (azimuthally symmetric) eccentrically nested spheres models, and good agreement has been obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999GeoJI.136..229M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999GeoJI.136..229M"><span id="translatedtitle">Spectral-finite <span class="hlt">element</span> approach to three-dimensional electromagnetic induction in 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>Martinec, Zden?k</p> <p>1999-01-01</p> <p>We present a spectral-finite <span class="hlt">element</span> approach to the forward problem of 3-Dglobal-scale electromagnetic induction in a heterogeneous conducting sphere excited by an external source current. It represents an alternative to a variety of numerical methods for 3-D global-scale electromagnetic induction modelling developed recently (the perturbation expansion approach and the finite <span class="hlt">element</span> and finite difference schemes). Two possible formulations of electromagnetic induction boundary-value problem are introduced. The boundary data used in the Dirichlet boundary-value problem consist of the horizontal components of the total magnetic induction measured on the <span class="hlt">Earth</span>'s surface, whereas the mixed boundary-value problem makes use of the scalar spherical harmonic expansion coefficients of the normal component of total magnetic induction in a near-space atmosphere. The latter problem is then reformulated in a weak sense and parametrized by vector spherical harmonics in the angular direction, whereas piecewise linear finite <span class="hlt">elements</span> span the radial direction. The solution is searched for using the Galerkin method, which leads to solving a system of linear algebraic equations. We employ the biconjugate gradient method with preconditioning to solve the Galerkin system numerically. Particular care is devoted to the construction of a preconditioner that stabilizes the solution and speeds up the convergence of iterations. The spectral-finite <span class="hlt">element</span> method and associated numerical code have been tested for 2-D (azimuthally symmetric) and 3-D (off-axis) eccentrically nested spheres models, and good agreement has been obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EOSTr..93R.202S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93R.202S"><span id="translatedtitle">While China's dominance in rare <span class="hlt">earths</span> dips, concerns remain about these and other <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Showstack, Randy</p> <p>2012-05-01</p> <p>China's dominance in the production of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) peaked with that nation producing 97% of them in 2010; this number already has dipped to 90% in 2012 as mines in other nations are coming online, according to REE expert Karl Gschneidner Jr., a professor at Iowa State University's Ames Laboratory. Chinese production could drop to 60% by 2014, with production increasing at mines in the United States and other countries, he said. However, this reduction in China's share of REE production does not signal an end to the production crisis in REEs and other critical minerals, Gschneidner and others noted during a 1 May panel discussion on critical materials shortages at the AGU Science Policy Conference in Washington, D. C. REEs are a group of 17 chemically similar metallic <span class="hlt">elements</span> used in a variety of electronic, optical, magnetic, and catalytic applications, and despite their name, they are relatively plentiful in the <span class="hlt">Earth</span>'s crust. China's control of known REE reserves has dropped from 75% in 1975 to 30.9% in 2012, with other regions also having large reserves, including the Commonwealth of Independent States (some former Soviet Republic states), the United States, and Australia, according to Gschneidner. Critical minerals are mineral commodities that are particularly important for a nation's economy or national defense that could potentially face supply disruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://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/abs/2009GeCoA..73.1609B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009GeCoA..73.1609B"><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/2013CEJG....5..112L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013CEJG....5..112L"><span id="translatedtitle">Consistent patterns of rare <span class="hlt">earth</span> <span class="hlt">element</span> distribution in accessory minerals from rocks of mafic-ultramafic complexes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lesnov, Felix Petrovich</p> <p>2013-03-01</p> <p>This paper summarizes analytical data accumulated in the world literature and other materials about the regularities of the REE distribution in minerals contained in ultramafic and mafic rocks as accessory phases. These minerals are tentatively divided into two groups. The first includes garnets, zircons, apatites and perovskites, which can accumulate increased amounts of REE in their structure. The second consists of minerals whose structure can accumulate only limited contents of these trace <span class="hlt">elements</span>. These are chrome-spinels, ilmenites, and micas. These minerals, in respect of REE <span class="hlt">geochemistry</span>, are studied to a varying degree because of the different levels of accumulations of these <span class="hlt">elements</span>, different degrees of occurrence in rocks, tiny sizes of their grains and other reasons. The analytical database formed on their basis includes about 600 original analyses. The overwhelming majority of presently available data on REE <span class="hlt">geochemistry</span> in accessory minerals from ultramafic and mafic rocks have been published only in the recent 15 years. The studies became possible due to the development and introduction of new highly sensible microprobe analyses allowing detection of REE and many other trace <span class="hlt">elements</span> in minerals grains directly in thin sections. The greatest numbers of these analyses were performed for garnets and zircons, fewer for apatites, and the fewest for chrome-spinels, ilmenites, micas, and perovskites. In general, the regularities of REE distribution in these minerals from ultramafic and mafic rocks are less studied compared to the rock-forming minerals from ultramafic and mafic rocks. Among the analytical methods, which were used to study the REE composition of accessory minerals, the most efficient was the mass-spectrometry with inductively coupled plasma (ICP-MS).</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 both students and educators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008GeCoA..72.3964P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008GeCoA..72.3964P"><span id="translatedtitle">Speciation of adsorbed yttrium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> on oxide surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piasecki, Wojciech; Sverjensky, Dimitri A.</p> <p>2008-08-01</p> <p>The distribution of yttrium and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (YREE) between natural waters and oxide mineral surfaces depends on adsorption reactions, which in turn depend on the specific way in which YREE are coordinated to mineral surfaces. Recent X-ray studies have established that Y 3+ is adsorbed to the rutile (1 1 0) surface as a distinctive tetranuclear species. However, the hydrolysis state of the adsorbed cation is not known from experiment. Previous surface complexation models of YREE adsorption have suggested two to four cation hydrolysis states coexisting on oxide surfaces. In the present study, we investigate the applicability of the X-ray results to rare <span class="hlt">earth</span> <span class="hlt">elements</span> and to several oxides in addition to rutile using the extended triple-layer surface complexation model. The reaction producing a hydrolyzed tetranuclear surface species 4>SOH+M+2HO=(>SOH)2_M(OH)2++4H was found to account for a significant fraction of the adsorbed Y 3+, La 3+, Nd 3+, Gd 3+, and Yb 3+ on rutile, hematite, alumina and silica over wide ranges of pH and ionic strength. Where adsorption data were available as a function of surface coverage for hematite and silica, an additional reaction involving a mononuclear species could be used to account for the higher surface coverages. However, it is also possible that some of the higher surface coverage data refer to surface precipitation rather than adsorption. The results of the present study provide an internally consistent basis for describing YREE adsorption which could be used to investigate more complex systems in which YREE compete both in aqueous solution and on mineral surfaces with alkaline <span class="hlt">earths</span> and ligands such as carbonate, sulfate, chloride and organic species, in order to build a predictive adsorption model applicable to natural waters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25283836','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25283836"><span id="translatedtitle">Recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> from the sulfothermophilic red alga Galdieria sulphuraria using aqueous acid.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Minoda, Ayumi; Sawada, Hitomi; Suzuki, Sonoe; Miyashita, Shin-ichi; Inagaki, Kazumi; Yamamoto, Takaiku; Tsuzuki, Mikio</p> <p>2015-02-01</p> <p>The demand for rare <span class="hlt">earth</span> <span class="hlt">elements</span> has increased dramatically in recent years because of their numerous industrial applications, and considerable research efforts have consequently been directed toward recycling these materials. The accumulation of metals in microorganisms is a low-cost and environmentally friendly method for the recovery of metals present in the environment at low levels. Numerous metals, including rare <span class="hlt">earth</span> <span class="hlt">elements</span>, can be readily dissolved in aqueous acid, but the efficiency of metal biosorption is usually decreased under the acidic conditions. In this report, we have investigated the use of the sulfothermophilic red alga Galdieria sulphuraria for the recovery of metals, with particular emphasis on the recovery of rare <span class="hlt">earth</span> metals. Of the five different growth conditions investigated where G. sulphuraria could undergo an adaptation process, Nd(III), Dy(III), and Cu(II) were efficiently recovered from a solution containing a mixture of different metals under semi-anaerobic heterotrophic condition at a pH of 2.5. G. sulphuraria also recovered Nd(III), Dy(III), La(III), and Cu(II) with greater than 90% efficiency at a concentration of 0.5 ppm. The efficiency remained unchanged at pH values in the range of 1.5-2.5. Furthermore, at pH values in the range of 1.0-1.5, the lanthanoid ions were collected much more efficiently into the cell fractions than Cu(II) and therefore successfully separated from the Cu(II) dissolved in the aqueous acid. Microscope observation of the cells using alizarin red suggested that the metals were accumulating inside of the cells. Experiments using dead cells suggested that this phenomenon was a biological process involving specific activities within the cells. PMID:25283836</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://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-Ni, whereas the corresponding highly siderophile <span class="hlt">elements</span> remained sequestered by the surviving metal. The highly siderophile <span class="hlt">elements</span> may have been introduced by a population of ~103 large (~1022 g) planetisimals, similar to those forming the lunar mare basins. ?? 1981.</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://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://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/2010AtmEn..44.2563M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AtmEn..44.2563M"><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/2014AGUFM.B32D..03Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B32D..03Z"><span id="translatedtitle">Cracking the Code of Soil Genesis. The Early Role of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaharescu, D. G.; Dontsova, K.; Burghelea, C. I.; Maier, R. M.; Huxman, T. E.; Chorover, J.</p> <p>2014-12-01</p> <p>Soil is terrestrial life support system. Its genesis involves tight interactions between biota and mineral surfaces that mobilize structural <span class="hlt">elements</span> into biogeochemical cycles. Of all chemical <span class="hlt">elements</span> rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are a group of 16 non-nutrient <span class="hlt">elements</span> of unusual geochemical similarity and present in all components of the surface environment. While much is known about the role of major nutrients in soil development we lack vital understanding of how early biotic colonization affects more conservative <span class="hlt">elements</span> such as REE. A highly controlled experiment was set up at University of Arizona's Biosphere-2 that tested the effect of 4 biological treatments, incorporating a combination of microbe, grass, mycorrhiza and uninoculated control on REE leaching and uptake in 4 bedrock substrates: basalt, rhyolite, granite and schist. Generally the response of REE to biota presence was synergistic. Variation in total bedrock chemistry could explain major trends in pore water REE. There was a fast transition from chemistry-dominated to a biota dominated environment in the first 3-4 months of inoculation/seeding which translated into increase in REE signal over time. Relative REE abundances in water were generally reflected in plant concentrations, particularly in root, implying that below ground biomass is the main sync of REE in the ecosystem. Mycorrhiza effect on REE uptake in plant organs was significant and increased with infection rates. Presence of different biota translated into subtle differences in REE release, reveling potential biosignatures of biolota-rock colonization. The results thus bring fundamental insight into early stages non-nutrient cycle and soil genesis.</p> </li> </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://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=oceanic+crust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Doceanic%2Bcrust','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870038811&hterms=oceanic+crust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Doceanic%2Bcrust"><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://adsabs.harvard.edu/abs/2014JVGR..287....1F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JVGR..287....1F"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in sinters from the geothermal waters (hot springs) on the Tibetan Plateau, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, Jin-Liang; Zhao, Zhen-Hong; Chen, Feng; Hu, Hai-Ping</p> <p>2014-10-01</p> <p>The mineralogical and geochemical composition of sinters from the geothermal areas on the Tibetan Plateau was determined. They occur as siliceous, salty and calcareous sinters but biogenic siliceous sinters were also found. The analyses indicate that there are no distinct inter -<span class="hlt">element</span> relationships between individual rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and other <span class="hlt">elements</span>. Formed from the same geothermal water, the mineralogical and chemical composition of the sinters is influenced by their genesis and formation conditions. The REE distributions depend on the origin of the sinters. Fe-Mn phases in sinters tend to scavenge more REEs from geothermal water. Neither the REE fractionation nor the Ce anomaly seems to be associated with Fe-Mn phases in the sinters. The fourth tetrads of some sinters display weak W-type (concave) effects. In contrast, the third tetrads present large effects in some sinters due to positive Gd anomalies. The origin of the positive Eu anomalies in some sinters seems to be caused by preferential dissolution of feldspars during water-rock interaction. The complexing ligands in geothermal water may contribute significantly to the fractionation of REEs in sinters. The dominant CO32- and HCO3- complexing in geothermal water favors enrichment of heavy REEs in calcareous sinters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MMTA...47..522R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MMTA...47..522R"><span id="translatedtitle">Grain Boundary Segregation of Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span> in Magnesium Alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robson, Joseph D.; Haigh, Sarah J.; Davis, Bruce; Griffiths, David</p> <p>2016-01-01</p> <p>Small additions of rare-<span class="hlt">earth</span> (RE) <span class="hlt">elements</span> have been shown to have a powerful effect in modifying the texture of wrought magnesium alloys, giving a highly beneficial effect in improving their formability. Recent work has shown that segregation of RE atoms to grain boundaries is important in producing this texture change. In this work, two Mg-RE systems have been studied Mg-Y and Mg-Nd using high-resolution scanning transmission electron microscopy that permits both imaging and <span class="hlt">elemental</span> analysis with a spatial resolution of better than 0.1 nm. The Mg-Y alloy, where the solubility and level of addition are relatively high, showed the RE texture change effect. This was accompanied by clustering of Y on the grain boundaries, consistent with previous studies of the Mg-Gd system. The Mg-Nd alloy, where the solubility and level of addition are relatively low, showed no texture change and no segregation. In this case, impurity <span class="hlt">elements</span> binding the RE into insoluble particles, rendering it ineffective. The results are analyzed by modifying a previous model for the solute drag effect on boundaries expected due to the RE additions. This predicts that both Gd and Y will strongly inhibit boundary motion, with Gd being approximately twice as effective as Y.</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://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 changes in heavy-mineral content. Variation in the quantity of fresh volcanic rock fragments is the other source of change in magnetite content. Magnetic-property variations probably arise primarily from changes in peak runoff. At low to moderate flows magnetic properties reflect only the quantities of heavy minerals derived from soil and highly weathered rock in the catchment. At high flows, however, fresh volcanic rock fragments may be produced by breaking of pebbles and cobbles, and such fragments greatly increase the magnetite content of the resulting sediment. Climatically controlled factors that would affect peak runoff levels include the accumulation and subsequent melting of winter snow pack, the seasonality of precipitation, and the degree of vegetation cover of the land surface. Our results do not distinguish amont the possible contributions of these disparate factors.</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750027184&hterms=ionic+liquids&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dionic%2Bliquids','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750027184&hterms=ionic+liquids&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dionic%2Bliquids"><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/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://ntrs.nasa.gov/search.jsp?R=19730043515&hterms=Europium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DEuropium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730043515&hterms=Europium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DEuropium"><span id="translatedtitle">Rare <span class="hlt">earths</span>, other trace <span class="hlt">elements</span> and iron in Luna 20 samples.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Helmke, P. A.; Blanchard, D. P.; Jacobs, J. W.; Haskin, L.; Haskin, A.</p> <p>1973-01-01</p> <p>The results of the analysis by neutron activation of six samples from the Luna 20 mission and one sample of less than 1 mm fines from Apollo 16 are reported. The concentrations of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in the samples of fines from Luna 20 and Apollo 16 are less than those found for corresponding materials from the mare areas but a negative Eu anomaly is still present. The concentrations of the REE in fines from Luna 20 are only about two-thirds as great as in the sample of Apollo 16 fines, but the concentration of Co, Sc and Cr are greater by factors ranging from 1.5 to 2.3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAP...118o4902Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAP...118o4902Z"><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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Z. G.; Wang, Z.; Wang, W. H.</p> <p>2015-10-01</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/abs/2013AcGeo..61..876S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AcGeo..61..876S"><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 ?-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.ncbi.nlm.nih.gov/pubmed/24385183','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24385183"><span id="translatedtitle">Origin of middle rare <span class="hlt">earth</span> <span class="hlt">element</span> enrichment in acid mine drainage-impacted areas.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grawunder, Anja; Merten, Dirk; Bchel, Georg</p> <p>2014-01-01</p> <p>The commonly observed enrichment of middle rare <span class="hlt">earth</span> <span class="hlt">elements</span> (MREE) in water sampled in acid mine drainage (AMD)-impacted areas was found to be the result of preferential release from the widespread mineral pyrite (FeS2). Three different mining-impacted sites in Europe were sampled for water, and various pyrite samples were used in batch experiments with diluted sulphuric acid simulating AMD-impacted water with high sulphate concentration and high acidity. All water samples independent on their origin from groundwater, creek water or lake water as well as on the surrounding rock types showed MREE enrichment. Also the pyrite samples showed MREE enrichment in the respective acidic leachate but not always in their total contents indicating a process-controlled release. It is discussed that most probably complexation to sulphite (SO3 (2-)) or another intermediate S-species during pyrite oxidation is the reason for the MREE enrichment in the normalized REE patterns. PMID:24385183</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://adsabs.harvard.edu/abs/2012JPhB...45b5001D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPhB...45b5001D"><span id="translatedtitle">Light shifts and magic wavelengths for heavy alkaline <span class="hlt">earth</span> <span class="hlt">elements</span>: Ba and Ra</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dammalapati, U.; Santra, B.; Willmann, L.</p> <p>2012-01-01</p> <p>In this paper, we investigate light shifts of heavy alkaline <span class="hlt">earth</span> <span class="hlt">elements</span> barium (Ba) and radium (Ra), which are interesting for optical lattice clocks and for permanent electric dipole moment searches. Detailed knowledge is required in the design of efficient loading of atoms from a magneto-optical trap into an optical dipole trap, to facilitate Doppler cooling while trapping and to achieve longer lifetimes of the trapped atoms with reduced heating rates. The wavelength dependence of light shifts of the ns2 1S0 ground state, the nsnp 3P1 and ns(n - 1)d 1D2 excited states in barium (n = 6) and the n s2 1S0 ground state, the nsnp 3P1 and ns(n - 1)d 3D2 excited states in radium (n = 7) are calculated. Several magic wavelengths in the visible and infrared regions accessible with commercial lasers for optical dipole trapping of Ba and Ra are identified.</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://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://adsabs.harvard.edu/abs/1995GeoRL..22..203D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995GeoRL..22..203D"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> deposition in pelagic sediment at the Cenomanian-Turonian Boundary, Exmouth Plateau</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dickens, Gerald R.; Owen, Robert M.</p> <p>1995-02-01</p> <p>Ocean Drilling Program (ODP) Site 762 (eastern Indian Ocean) includes a section of sediment that spans the Cenomanian-Turonian Boundary (CTB) and was deposited along a continental margin during a period of widespread oceanic O2 deficiency. The rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) content of pre- and post-boundary sediment is similar to that of present-day continental slope material deposited in well-oxygenated seawater, whereas the CTB section is characterized by significantly depleted REE abundances, a bulk Ce anomaly that increases to maximum of 1.0, and a REE pattern that resembles that of present-day fluvial material. We suggest the change in REE patterns reflects release of scavenged REEs upon reductive dissolution of authigenic Fe-Mn oxyhydroxides, such that sediment deposited during the CTB is dominated by the lithogeneous REE fraction. These results are consistent with recent models concerning pervasive fractionation of Mn and Fe and redirection of Mn in pelagic CTB waters.</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> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/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 ?m) REE record of a sediment core MD05-2925 (920.61'S, 15127.61'E, water depth 1660 m) from the Solomon Sea. The REE diagram shows two dominant sources of local seawater and nearby terrestrial input. The variability of foraminiferal REE/Ca time series is different from Mg/Ca-inferred sea surface temperature and ?18O records during the past 60-kyr. This inconsistency suggests that planktonic foraminiferal REE content cannot result only from changes in ice volume and temperature. Synchroneity between high planktonic foraminiferal REE content and Antarctic ice core dust amount record implies the same dust sources, probably from Australia or mainland China. Our results suggest that foraminiferal REE can potentially be as a new dust proxy and record dry/humid conditions at the source area.</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://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://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://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://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://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> <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/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 break if individual links become unavailable. Secondly, a single service cannot interpret links if downstream solutions differ in their implementation schemas. Emerging efforts driven by the European Persistent Identifier Consortium (EPIC) aim to establish a default mechanism for structural <span class="hlt">elements</span> at the Handle level. We motivate to make applications, which take part in the data lifecycle, aware of data derivation provenance and let them provide additional <span class="hlt">elements</span> to the provenance graph. Since they are also Handles, DataCite DOIs can act as a corner stone and provide an entry point to discover the provenance graph. References B. Lawrence, C. Jones, B. Matthews, S. Pepler, and S. Callaghan, "Citation and peer review of data: Moving towards formal data publication," Int. J. of Digital Curation, vol. 6, no. 2, 2011. L. Moreau, "The foundations for provenance on the web," Foundations and Trends® in Web Science, vol. 2, no. 2-3, pp. 99-241, 2010. F. Toussaint, T. Weigel, H. Thiemann, H. Höck, M. Stockhause: "Application Examples for Handle System Usage", submitted to AGU 2012 session IN009.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6700515','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6700515"><span id="translatedtitle">Annual review of <span class="hlt">earth</span> and planetary sciences. Volume 8</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Donath, F.A.; Stehli, F.G.; Wetherill, G.W.</p> <p>1980-01-01</p> <p>Papers are presented on the <span class="hlt">geochemistry</span> of evaporitic lacustrine deposits, the deformation of mantle rocks, the dynamics of sudden stratospheric warmings, the equatorial undercurrent, geomorphological processes on planetary surfaces, and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in petrogenetic studies of igneous systems. Consideration is also given to evolutionary patterns in early Cenozoic animals, the origin and evolution of planetary atmospheres, the moons of Mars, and refractory inclusions in the Allende meteorite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Litho.248..432F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Litho.248..432F"><span 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 was added to the peridotite, as opposed to being exchanged. These data allows for more accurate constraints of the water/rock mass exchange ratios during serpentinization in these rocks (~ 1000 to 17,000) that are at least an order of magnitude lower than using typical mantle and seawater endmembers. These data provide strong evidence that serpentinization may also be a sink for the light REE, with implications for the refertilization of the peridotite during serpentinization, and the cycling of these <span class="hlt">elements</span> through the subduction system and into the upper mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....14148P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....14148P"><span id="translatedtitle">Tracing irradiation-induced defect state of monazite by photoluminescence of rare <span class="hlt">Earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panczer, G.; Seydoux-Guillaume, A. M.; Montel, J. M.; Champagnon, B.</p> <p>2003-04-01</p> <p>Natural monazite is known in contrast to zircon, to almost never be found in the metamict state (Ewing, 1975) despite the fact that it received intensive radiation doses during geologic history by U and Th incorporation. Radiation damages in natural monazite seems to be limited to isolated domains within the crystal (Meldrum et al., 1998). Such property controlled the fact that the monazite lattice is easily healed even at low temperature as it was shown by TEM, XRD and Raman spectrometry (Seydoux-Guillaume et al., 2002). In order to estimate the degree of disorder and the healing of defects we used trivalent neodymium as an internal luminescent probe (Gaft et al., 2001). As a matter of fact the radiative electronic transitions of rare <span class="hlt">earth</span> <span class="hlt">elements</span> are very sensible to the short-range crystallographic order around them. Three natural monazites thermally untreated and quenched at 450, 500, 700, 800 and 1000^oC were analyzed under 514 nm Argon laser excitation with a Renishaw microspectrometer. Nd3+ emission was recorded in the range of 750 nm to 1 ?m. The ^4F3/2 rightarrow ^4I9/2 transition parameters (position and width) show that 1) the position of the Stark levels do not change during thermal treatment, and 2) that the emission line widths decrease continuously (from 25 to 37%) from room temperature to 1000^oC. These results indicates that before annealing, sub sites of Nd were present with slight different environments induced by internal irradiation induced displacement of ions around them (short range disorder). After thermal treatment a continuous reorganization of the lattice occurs up to 1000^oC with quite strong rearrangement of the environment around the rare-<span class="hlt">earth</span> leading to a decrease of the Nd sub site number. Thus, the luminescent probe reveals that defect healing continue at much higher temperatures than what was previously reported indicating that luminescence is a very sensible tool to appreciate the degree of disorder in mineral phases. Gaft M., Panczer G., Reisfeld R. &Uspensky E. (2001) Laser-induced time-resolved luminescence as a tool for rare-<span class="hlt">earth</span> <span class="hlt">element</span> identification in minerals., Phys. Chem. Minerals, 28, 347-363.</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 part of this study. Red muds from these deposits contain on average 900 ppm REE compared with typical values of <100 ppm to ~500 ppm REE in the bauxites. Extraction of REE from red muds has been shown to be feasible [5,7] although it is challenging due to the heterogeneous spatial distribution of REE in the primary bauxite deposits [8], an unclear understanding of the mobility of REE in red mud tailings ponds, and the need for development of appropriate processing methods. However, the resource potential of red muds in Europe is significant with approximately 3.5 Mt of bauxite ore extracted in 2012 [2], resulting in approximately 1.4 Mt of red mud from the production of alumina. In addition a large volume of stockpiled red muds exists from historical processing of bauxites, the total of which is not well constrained. Understanding the REE potential of both bauxites and red muds is integral to an assessment of European REE resources. References [1] European Commission, "Report on critical raw materials for the EU. Report of the Ad hoc Working Group on defining critical raw materials". May 2014. [2] T. Brown, N. Idoine, E. Raycraft, R. Shaw, E. Deady, J. Rippingale, T. Bide, C. Wrighton, J. Rodley, "World Mineral Production 2008-12" British Geological Survey, Keyworth, Nottingham, 2014. [3] Z. Maksimović and G. Pantó, "Authigenic rare <span class="hlt">earth</span> minerals in karst-bauxites and karstic nickel deposits". In: A.P. Jones, F. Wall and C.T. Williams, Rare <span class="hlt">earth</span> minerals, chemistry, origin and ore deposits, Chapter 10, pp. 257-279, 1996. [4] G. Bárdossy, "Karst Bauxites, Bauxite Deposits on Carbonate Rocks". Elsevier, 444pp, 1982. [5] M. Ochsenkühn-Petropoulou, T. Lyberopoulou, and G. Parissakis, "Direct determination of lanthanides, yttium and scandium in bauxites and red mud from alumina production", Analytica Chimica Acta, vol. 296, no. 3, pp. 305-313, October 1994. [6] É. Deady, E. Mouchos, K. Goodenough, B. Williamson and F. Wall. "Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Karst-Bauxites: a Novel Untapped European Resource?" ERES 1st European Rare <span class="hlt">Earth</span> Resources conference, Milos, Greece, (5-6/09/2014). [7] A. Wagh and W. Pinnock, "Occurrence of scandium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Jamaican bauxite waste", Economic Geology, vol. 82, no. 3, pp. 757-761, May 1987. [8] G. Mongelli, "Ce-anomalies in the textural components of Upper Cretaceous karst bauxites from the Apulian carbonate platform (southern Italy)", Chemical Geology, vol. 140, no. 1, pp. 69-79, June 1997. Additional resources: www.eurare.eu; www.redmud.org.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JSSCh.171....3P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JSSCh.171....3P"><span id="translatedtitle">Determination of trace amounts of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in highly pure neodymium oxide by sector field inductively coupled plasma mass spectrometry (ICP-SFMS) and high-performance liquid chromatography (HPLC) techniques</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pedreira, W. R.; Sarkis, J. E. S.; da Silva Queiroz, C. A.; Rodrigues, C.; Tomiyoshi, I. A.; Abro, A.</p> <p>2003-02-01</p> <p>Recently rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) have received much attention in fields of <span class="hlt">geochemistry</span> and industry. Rapid and accurate determinations of them are increasingly required as industrial demands expand. Sector field inductively coupled plasma mass spectrometry (ICP-SFMS) with high-performance liquid chromatography (HPLC) has been applied to the determination of REE. HR ICP-MS was used as an <span class="hlt">element</span>-selective detector for HPLC in highly pure materials. The separation of REE with HPLC helped to avoid erroneous analytical results due to spectral interferences. Sixteen <span class="hlt">elements</span> (Sc, Y and 14 lanthanides) were determined selectively with the HPLC/ICP-SFMS system using a concentration gradient methods. The detection limits with the HPLC/ICP-SFMS system were about 0.5-10 pg mL -1. The percentage recovery ranged from 90% to 100% for different REE. The %RSD of the methods varying between 2.5% and 4.5% for a set of five ( n=5) replicates was found for the IPEN's material and for the certificate reference sample. Determination of trace REEs in two highly pure neodymium oxides samples (IPEN and Johnson Matthey Company) were performed. In short, the IPEN's materials which are highly pure (>99.9%) were successfully analyzed without spectral interferences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V42A..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V42A..01C"><span id="translatedtitle">Subduction Zone Redox and the Deep <span class="hlt">Earth</span> Cycles of Sulfur and Chalcophile <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Canil, D.</p> <p>2013-12-01</p> <p>Subduction at convergent plate margins is a return flux to the mantle of rocks influenced by weathering, hydrothermal activity, atmospheric exchange, or bio-mineralization in the exosphere. The latter exogenic processes modify the long-term abundance and behaviour of certain <span class="hlt">elements</span> in the deeper <span class="hlt">earth</span> that can be traced over time in the chemistry of mantle-derived magmas. The redox budget of subduction is controlled by the flux of oxidized versus reduced forms of Fe, S, H, or C, and impacts the long-term evolution of oxygen on the planet, critical for life in the exosphere. In particular, the sulfur cycle is specifically tied to the evolution of oxygen on <span class="hlt">Earth</span>'s surface over time and critical to biogeochemical cycles on the surface. The behaviour of sulfur in the exogenic system is well-studied and fairly well understood using sedimentary records. An originally sulfidic ocean on <span class="hlt">Earth</span> gave way with time and oxygenation to one that is sulfate dominated over the last two billion years. In contrast, far less is known of the deep <span class="hlt">earth</span> cycle of S, and more so its history. The record of the endogenic cycle can only be monitored via what comes out of the mantle (magmas and their gases), or what goes down via subduction (hydrothermally-altered or weathered subducted lithosphere). Interest in the endogenic cycle of S is not new but several outstanding conundrums remain for sulfur in arc magmas that point to the importance of the subduction process. A hitherto ignored component of the paradox of the sulfur cycle is the sedimentary veneer that sits atop the subducted oceanic basalt crust. Compilations show only 0.12 wt% S in altered ocean basalt crust, but up to 10 times that amount in oceanic sediments, tied to their Fe content (in pyrite). These abundances may seem trivial, but the behaviour of this small amount of S in subduction is not fully appreciated and its oxidation potential in the arc mantle is enormous. The conversion of subducted sulfide to sulfate is a 8-electron change in redox state, with significant oxidation/ reduction capacity. The concomitant higher fO2 can in turn facilitate the mobility and/or extraction of chalcophile metals from the arc mantle into magmas by the melting process in arcs. Sedimentary records show that through most of <span class="hlt">Earth</span>'s history sulfur has mostly been subducted in reduced form as sulfide. The fate of sulfide in ocean sediments during subduction (and subsequent dehydration or melting) has not been thoroughly investigated, nor its interplay with other redox couples (C, H, Fe) in sediments, subducted basalt or in the mantle. I examine the redox controls on sulfate versus sulfide stability in subducted oceanic crust, and their disposition relative to other redox couples in the mantle. Sulfate-sulfide equilibria impact the fate of sulfur and chalcophile <span class="hlt">elements</span> in subducted lithologies, especially if dehydrated or melted depending on a variety subduction P-T trajectories. In this light, new high P-T experiments show the utility of Cu as a proxy for S in the subduction system . These proxies can potentially be applied to examine the deep S cycle, subduction redox and its role in arc magmatism over geologic time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004InEPS.113..649R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004InEPS.113..649R"><span id="translatedtitle">Late Archaean mantle metasomatism below eastern Indian craton: Evidence from trace <span class="hlt">elements</span>, REE <span class="hlt">geochemistry</span> and SrNdO isotope systematics of ultramafic dykes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roy, A.; Sarkar, A.; Jeyakumar, S.; Aggrawal, S. K.; Ebihara, M.; Satoh, H.</p> <p>2004-12-01</p> <p>Trace, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE), Rb-Sr, Sm-Nd and O isotope studies have been carried out on ultramafic (harzburgite and lherzolite) dykes belonging to the newer dolerite dyke swarms of eastern Indian craton. The dyke swarms were earlier considered to be the youngest mafic magmatic activity in this region having ages not older than middle to late Proterozoic. The study indicates that the ultramafic members of these swarms are in fact of late Archaean age (Rb-Sr isochron age 2613 177 Ma, Sri 0.702 0.004) which attests that out of all the cratonic blocks of India, eastern Indian craton experienced earliest stabilization event. Primitive mantle normalized trace <span class="hlt">element</span> plots of these dykes display enrichment in large ion lithophile <span class="hlt">elements</span> (LILE), pronounced Ba, Nb and Sr depletions but very high concentrations of Cr and Ni. Chondrite normalised REE plots exhibit light REE (LREE) enrichment with nearly flat heavy REE (HREE; (?HREE)N 2-3 times chondrite, (Gd/Yb)N 1). The ?Nd(t) values vary from +1.23 to -3.27 whereas ?18O values vary from +3.16 to +5.29 (average +3.970.75) which is lighter than the average mantle value. Isotopic, trace and REE data together indicate that during 2.6 Ga the nearly primitive mantle below the eastern Indian Craton was metasomatised by the fluid ( silicate melt) coming out from the subducting early crust resulting in LILE and LREE enriched, Nb depleted, variable ?Nd, low Sri(0.702) and low ?18O bearing EMI type mantle. Magmatic blobs of this metasomatised mantle were subsequently emplaced in deeper levels of the granitic crust which possibly originated due to the same thermal pulse.</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.; Nmery, J.; Duvert, C.; Ayrault, S.; Lefvre, I.; Legout, C.; Bont, 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 affected by gully erosion, rill or sheet erosion have been delineated. Furthermore, the measurement of radionuclide content in suspended sediment after the snowmelt suggests that most of this sediment consists in resuspended material rather than on newly eroded soil. In the Mexican watershed, a different contribution of andisols and acrisols to erosion is suspected. Overall, the bulk of erosion is generated by rather small areas within the watershed. In this region characterised by a succession of wet and dry seasons, the Be-7 content in rainfall and sediment has been measured at the scale of a 2.5 km2 sub-watershed in order to better understand the erosion transfer between hillslopes and rivers during the rainy season. This outlines the contribution of individual storms to seasonal erosion. Overall, this study brings important insights about sediment sources and fluxes within these watersheds located in contrasted environments. A further step consists in comparing experimental results with model outputs, and to evaluate the impact of on-going erosion mitigation measures.</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://www.ncbi.nlm.nih.gov/pubmed/25710372','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25710372"><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=pubmed">PubMed</a></p> <p>Horiike, Takumi; Yamashita, Mitsuo</p> <p>2015-05-01</p> <p>With an aim to develop a highly efficient method for the recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) by using microorganisms, we attempted to isolate dysprosium (Dy)-accumulating microorganisms that grow under acidic conditions from environmental samples containing high concentrations of heavy metals. One acidophilic strain, T9, which was isolated from an abandoned mine, decreased the concentration of Dy in medium that contained 100 mg/liter Dy to 53 mg/liter Dy after 3 days of cultivation at pH 2.5. The Dy content in the cell pellet of the T9 strain was 910 μg/mg of dry cells. The T9 strain also accumulated other REEs. Based on the results of 28S-D1/D2 rRNA gene sequencing and morphological characterization, we designated this fungal strain Penidiella sp. T9. Bioaccumulation of Dy was observed on the cell surface of the T9 strain by <span class="hlt">elemental</span> mapping using scanning electron microscopy-energy dispersive X-ray spectroscopy. Our results indicate that Penidiella sp. T9 has the potential to recover REEs such as Dy from mine drainage and industrial liquid waste under acidic conditions. 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 K?2 /K?1 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 K?2 /K?1 X-rays from Tm and Yb irradiated under different conditions. These REE are particularly interesting to start with since Yb has an electronic configuration where all the subshells are completely filled, whilst Tm misses one electron in the 4f subshell. Ultrapure oxides of each <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> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1112002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1112002M"><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 identification of adulteration of high priced pumpkin seed oil with cheap neutral tasting refined oils. Interestingly enough, the variations of the REE patterns between oils from different regions are much more pronounced than their host soils. Thus we assume that microbiological processes in the rhizosphere are in control of the REE uptake into the plant. Regional variations of the microbiological composition of the soils and probably not only a priori the bulk soil composition of the minerals in the soil are the cause of the regional variations making it possible to identify the geographic origin of pumpkin seeds and as a consequence the pumpkin seed oil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712017H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712017H"><span id="translatedtitle">Bioavailable concentrations of germanium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soil fractions</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; Wiche, Oliver</p> <p>2015-04-01</p> <p>As there is an increasing demand for germanium and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> due to their diverse application in modern technologies (optical cables, permanent magnets in wind power stations), there is an interest to investigate a new approach to extract these ubiquitous but disperse existing <span class="hlt">elements</span> - via Phytomining. But before this method can be established, a thorough understanding of processes regarding the intake of germanium (Ge) and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) is necessary. The aim of this work was to get insights or hints on correlations between the concentrations and the fractionation of Ge and REEs in the soil and the concentrations in plants - in other words we wanted to conduct research on bioavailable concentrations of Ge and REEs in soil fractions. On 18 sites situated around Freiberg, Saxony we took samples of soil and plants. To extract the <span class="hlt">elements</span> from the plant material a decomposition with hydrofluoric acid was used. The soil samples was examined by a sequential extraction with seven steps (mobile, carbonatic, oxidisable, amorphic oxides, crystalline oxides, phytoliths and secondary clay minerals, residual or siliceous). The amounts of the REEs showed a high correlation between each other, so neodymium can be regarded as a proxy for all REEs. The average total amount of Ge in the soil samples was around 1.45 mg/kg, the one of neodymium (Nd) was around 25 mg/kg. Both values equal the overall average in the <span class="hlt">earth</span> crust. Concerning the Ge concentration in soil the residual siliceous fractions constituted for 70% of total, whereas the fractions V and VI - dedicated as crystalline oxides and phytoliths/secondary clay minerals - made out for 25%. Only 5% of the total amount of Ge in soil accounted for the fractions I to IV. There was found a statistical significant correlation between the absolute Ge concentrations in these latter soil fractions with the Ge concentration in plant material of the same site. Therefore it seems that the fractions I to IV could be regarded as a proxy for the bioavailable pool of Ge in soils. Concerning Nd the residual siliceous fractions made out for 60% of the total, whereas the fraction III (oxidisable) constitutes for 30%. The remaining 10% accounted for the other soil fractions. No correlation between the concentration in one soil fraction and the concentration in plant material from the same site could be found. There was also no correlation between the total amount in soil and the concentration in plant material from the same site neither for the REEs nor for Ge. These results can give only hints on the processes regarding the mobilisation of the bioavailable pool of Ge and REEs. Further investigations are necessary and will be taken in the PhytoGerm project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V13G..02M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V13G..02M"><span id="translatedtitle">Linking rare <span class="hlt">earth</span> <span class="hlt">element</span> zoning in major and accessory minerals to better understand metasedimentary migmatites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matthews, J. A.; Kelly, N. M.; Koenig, A.; Harley, S. L.</p> <p>2011-12-01</p> <p>Trace <span class="hlt">element</span> signatures from major and accessory minerals are increasingly used to place constraints on the ages of tectonothermal events and gain insights into processes operating in the deep continental crust. Minerals such as garnet, zircon or monazite represent sensitive recorders of events if a solid understanding exists of what trace <span class="hlt">element</span> signatures represent. A study underway on granulite facies migmatites is providing insights into trace <span class="hlt">element</span> signatures in garnet, and when integrated with in situ, microbeam analysis of zircon and monazite, is allowing a complex polymetamorphic history to be deciphered. The Larsemann Hills, east Antarctica, are composed of felsic orthogneisses and metasediments that were affected by high-grade metamorphism and partial melting at c. 7 kbar and >800 C. Initially interpreted to have experienced a single cycle of metamorphism at c. 550-530 Ma, recent ages suggest that the area was affected by an earlier high-grade event at c. 900 Ma; the timing of migmatization relative to these two events remains uncertain. To address this, a detailed study has targeted metasedimentary migmatites. Garnet, zircon and monazite were analysed from melanosome, leucosome and selvage domains. Garnet (predominantly almandine-pyrope) preserves little, if any, major <span class="hlt">element</span> zoning. In contrast, it records systematic within-grain variations in heavy rare <span class="hlt">earth</span> <span class="hlt">element</span> (HREE) concentration depending on textural context. Garnet within residuum domains displays broad cores with flat HREE slopes in chondrite-normalized plots, but are HREE-depleted (negative slopes) at boundaries adjacent to leucosome. In contrast, garnet boundaries adjacent to cordierite-rich selvages are typically HREE-enriched, with positive-sloping patterns. It is interpreted that core-rim depletions in HREE may reflect evolution of the whole-rock reservoir towards depletion during migmatization and garnet growth. Enrichment in garnet HREE adjacent to selvage domains likely resulted from local reaction between solids and melts either during melt transit and/or crystallization. Monazite, which is preferentially located in leucosome domains, preserves ages that reflect growth at c. 900 Ma and c. 530 Ma, although trace <span class="hlt">element</span> signatures are ambiguous. However, zircon, which is preferentially located in selvage domains, preserves c. 530 Ma rims with depleted, flat to negatively sloping HREE patterns. It is interpreted that these zircon rims grew in, or near to equilibrium with garnet cores and rims during partial melting, and may date at least part of migmatite formation in the Larsemann Hills. They do not date the final crystallization of melts and development of selvage domains. Preliminary results of this study have shown that the trace <span class="hlt">element</span> composition of garnet from high-temperature terrains can be a powerful tool in tracking metamorphic and melting processes where major <span class="hlt">elements</span> zoning is no longer preserved. This study also demonstrates the utility of textural context when interpreting trace <span class="hlt">element</span> patterns and ages from dateable accessory minerals in rocks from polycyclic metamorphic terrains.</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, Cline; 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://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://adsabs.harvard.edu/abs/2014JAfES..91...66K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAfES..91...66K"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and petrogenesis of the granitoids and high-K andesite hosting gold mineralisation in the Archean Musoma-Mara Greenstone Belt, Tanzania</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kazimoto, Emmanuel Owden; Ikingura, Justinian R.</p> <p>2014-03-01</p> <p>Modern and ancient active continental margins are well known for their potential for hosting important gold deposits. The Neoarchean Musoma-Mara Greenstone Belt of the Tanzania Craton is also known for hosting several important gold deposits. Previous geochemical studies of the belt demonstrated that the rocks formed along Neoarchean convergent margins. The host rocks of the three important deposits in this belt had not yet been geochemically investigated. Therefore, we studied the host rocks of the Gokona, Nyabigena and Nyabirama gold deposits in the Neoarchean Musoma-Mara Greenstone Belt of the Tanzania Craton to determine the tectonic setting of their formation and constrain their petrogenesis. The host rocks of the Gokona and Nyabigena deposits are classified as high-K andesite, whereas the host rocks of the Nyabirama deposit are classified primarily as trondhjemite and granite and minor granodiorite (TGG). The high-K andesite and TGG were formed in an active continental margin similar to that of other Neoarchean volcanic rocks found in the Musoma-Mara Greenstone Belt. The host rocks contain low Ni and Cr concentrations and are characterised by negative Eu anomalies (Eu/Eu* = 0.67-0.72 and 0.17-0.6). The chondrite-normalised rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns of the rocks display strong enrichment in light REEs over heavy REEs (high-K andesite (La/Yb)N = 21.7-35.6, and TGG (La/Yb)N = 2.4-94.4). Moreover, the primitive normalised diagrams show enrichment in large-ion lithophile <span class="hlt">elements</span> (Ba, Rb, Th and K), negative Nb and Ta anomalies and depletion in heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> and high field-strength <span class="hlt">elements</span> (Y and Ti). The high-K andesite has a Nb/Ta value close to that of depleted mantle (mean = 15.0), lower Zr/Sm values (19.4-30.6) and higher concentrations of REEs, large ion lithophile <span class="hlt">elements</span>, Sr (607 ppm) and Y than in the TGG. The TGG has a low mean Nb/Ta value (13.2) and Sr concentration (283 ppm) and a lower amount of HREEs and higher values of Zr/Sm (32.5-91.0) compared to the high-K andesite. However, all of the rock types contain high Ta/Yb and Th/Yb values (high-K andesite and granitoids; mean = 5.9 and 0.8, 17 and 21.3). These characteristics are interpreted as an indication of the formation of the Gokona, Nyabigena and Nyabirama host rocks from the hydrous partial melting of mantle peridotite, similar to the evolution of classical island arc rocks. The primary melts subsequently underwent fractional crystallisation to form high-K andesite, dacite and TGG prior to their extrusion or emplacement in the continental crust.</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=17.44.3), 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 1.60.5 by flattening the moderately fractionated REE pattern seen in pure aqueous fluids. The solubilities in hydrous haplogranite melt are moderate in comparison to those observed in aqueous fluids and do not lead to pronounced REE fractionation. Therefore, REE can be effectively mobilized and fractionated by aqueous fluids, compared to felsic hydrous melts. Furthermore, the aqueous fluid chemistry has a major role in determining REE mobilities and fractionation upon slab dehydration in addition to the significant control exerted by temperature. Our results show that chloride-bearing slab-derived aqueous fluids have a significant contribution to the formation of REE-signatures in arc-magmas, especially at lower slab surface temperatures.</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 crack that cross-cut the calcite filling the vesicles or the volcanic glass. They are also closely associated with Ni-Mg bearing phyllosilicates, which appear to nucleate from alteration of olivine and clinopyroxenes. Further investigations are done to evidence and confirm an anterior magmatic enrichment. On the basis of these observations, we believe that the anomalous enrichment observed in seafloor sediments could derive from abnormally-rich provinces corresponding to aerial basaltic formations from oceanic islands primarily enriched during weathering processes (Melleton et al., 2014). Melleton et al. (2014). Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> enrichment of Pacific sea-floor sediments: the view from volcanic islands of Polynesia. In preparation.</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</i> reservoir conditions. Our research has shown that the REE signature imparted to the formation fluid by the introduction of CO₂ to the formation, can be measured and tracked as part of an MMV program. Additionally, this REE fingerprint may serve as an ideal tracer for fluid migration, both within the CCS target formation, and should formation fluids migrate into overlying aquifers. However application of REE and other trace <span class="hlt">elements</span> to CCS system is complicated by the high salt content of the brines contained within the target formations. In the United States by regulation, in order for a geologic reservoir to be considered suitable for carbon storage, it must contain formation brine with total dissolved solids (TDS) > 10,000 ppm, and in most cases formation brines have TDS well in excess of that threshold. The high salinity of these brines creates analytical problems for <span class="hlt">elemental</span> analysis, including <span class="hlt">element</span> interference with trace metals in Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) (i.e. <span class="hlt">element</span> mass overlap due to oxide or plasma phenomenon). Additionally, instruments like the ICP-MS that are sensitive enough to measure trace <span class="hlt">elements</span> down to the parts per trillion level are quickly oversaturated when water TDS exceeds much more than 1,000 ppm. Normally this problem is dealt with through dilution of the sample, bringing the water chemistry into the instruments working range. However, dilution is not an option when analyzing these formation brines for trace metals, because trace <span class="hlt">elements</span>, specifically the REE, which occur in aqueous solutions at the parts per trillion levels. Any dilution of the sample would make REE detection impossible. Therefore, the ability to use trace metals as <i>in situ</i> natural tracers in high TDS brines environments requires the development of methods for pre-concentrating trace <span class="hlt">elements</span>, while reducing the salinity and associated <span class="hlt">elemental</span> interference such that the brines can be routinely analyzed by standard ICP-MS methods. As part of the Big Sky Carbon Sequestration Project the INL-CAES has developed a rapid, easy to use process that pre-concentrates trace metals, including REE, up to 100x while eliminating interfering ions (e.g. Ba, Cl). The process is straightforward, inexpensive, and requires little infrastructure, using only a single chromatography column with inexpensive, reusable, commercially available resins and wash chemicals. The procedure has been tested with synthetic brines (215,000 ppm or less TDS) and field water samples (up to 5,000 ppm TDS). Testing has produced data of high quality with REE capture efficiency exceeding 95%, while reducing interfering <span class="hlt">elements</span> by > 99%.</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 conditions. Our research has shown that the REE signature imparted to the formation fluid by the introduction of CO₂ to the formation, can be measured and tracked as part of an MMV program. Additionally, this REE fingerprint may serve as an ideal tracer for fluid migration, both within the CCS target formation, and should formation fluids migrate into overlying aquifers. However application of REE and other trace <span class="hlt">elements</span> to CCS system is complicated by the high salt content of the brines contained within the target formations. In the United States by regulation, in order for a geologic reservoir to be considered suitable for carbon storage, it must contain formation brine with total dissolved solids (TDS) > 10,000 ppm, and in most cases formation brines have TDS well in excess of that threshold. The high salinity of these brines creates analytical problems for <span class="hlt">elemental</span> analysis, including <span class="hlt">element</span> interference with trace metals in Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) (i.e. <span class="hlt">element</span> mass overlap due to oxide or plasma phenomenon). Additionally, instruments like the ICP-MS that are sensitive enough to measure trace <span class="hlt">elements</span> down to the parts per trillion level are quickly oversaturated when water TDS exceeds much more than 1,000 ppm. Normally this problem is dealt with through dilution of the sample, bringing the water chemistry into the instruments working range. However, dilution is not an option when analyzing these formation brines for trace metals, because trace <span class="hlt">elements</span>, specifically the REE, which occur in aqueous solutions at the parts per trillion levels. Any dilution of the sample would make REE detection impossible. Therefore, the ability to use trace metals as in situ natural tracers in high TDS brines environments requires the development of methods for pre-concentrating trace <span class="hlt">elements</span>, while reducing the salinity and associated <span class="hlt">elemental</span> interference such that the brines can be routinely analyzed by standard ICP-MS methods. As part of the Big Sky Carbon Sequestration Project the INL-CAES has developed a rapid, easy to use process that pre-concentrates trace metals, including REE, up to 100x while eliminating interfering ions (e.g. Ba, Cl). The process is straightforward, inexpensive, and requires little infrastructure, using only a single chromatography column with inexpensive, reusable, commercially available resins and wash chemicals. The procedure has been tested with synthetic brines (215,000 ppm or less TDS) and field water samples (up to 5,000 ppm TDS). Testing has produced data of high quality with REE capture efficiency exceeding 95%, while reducing interfering <span class="hlt">elements</span> by > 99%.« less</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 crystallize from a molten mantle, and become entrained in the convecting melt, or eventually settle out at the bottom. The entrainment and settling process has been studied in detail (e.g., Tonks and Melosh, 1990), and is a potential mechanism for differentiation between the deep and shallow parts of <span class="hlt">Earth</span>'s mantle. The lithophile <span class="hlt">elements</span>, those <span class="hlt">elements</span> that have D(metal/silicate) <1, fall into many different subclasses and all hold information about the deep mineral structure of the mantle. Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have proven to be useful: europium anomalies have helped elucidate the role of plagioclase in lunar crust formation (e.g., Schnetzler and Philpotts, 1971; Weill et al., 1974), and LREE/HREE depletion and enrichment are indicators of partial melting in the presence of garnet in the mantle. High-field-strength <span class="hlt">elements</span> (HFSEs) - niobium, zirconium, tantalum, and hafnium - are all refractory and hence more resilient to fractionation processes such as volatility or condensation. They also have an affinity for ilmenite and rutile, and can explain differences between lunar and martian samples as well as features of <span class="hlt">Earth</span>'s continental crust ( Taylor and McLennan, 1985). Alkaline-<span class="hlt">earth</span> and alkaline <span class="hlt">elements</span> include rubidium, strontium, barium, potassium, caesium, and calcium, some of which are involved in radioactive decay couples, e.g., Rb-Sr and K-Ar. The latter is important in understanding the contribution of radioactive decay to planetary heat production, and potential deep sources of radiogenic argon (see Chapter 2.06). Rubidium and potassium are further useful as tracers of hydrous phases such as mica and amphibole. Possible fractionation of any of these <span class="hlt">elements</span> from chondritic abundances (see Chapter 2.01) can be assessed with the knowledge of partition coefficients. In this chapter we summarize our understanding of mineral/melt fractionation of minor and trace <span class="hlt">elements</span> at high pressures and temperatures and discuss the implications for mantle differentiation.</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.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://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/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://www.osti.gov/scitech/biblio/5757130','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5757130"><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://www.osti.gov/scitech">SciTech Connect</a></p> <p>Clague, D.A.; Frey, F.A.; Thompson, G.; Rindge, S.</p> <p>1981-10-10</p> <p>A wide range of rock types (abyssal tholeiite, Fe-Ti-rich basalt, andesite, and rhyodacite) were dredged from near 95/sup 0/ W and 85/sup 0/ W 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 P/sub 2/O/sub 5//K/sub 2/O ratio averages 0.83 at 95/sup 0/W and 1.66 at 85/sup 0/W and 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, with (La/Sm)/sub EF/ = 0.67 at 95/sup 0/W and 0.46 at 85/sup 0/W. The sequence of fractional lavas differs for the two areas and indicates earlier fractionation of apatite and titanomagnetite in the lavas from 95/sup 0/W. Incompatible trace <span class="hlt">element</span> abundances in 26 samples are used to infer that the range of Fe-Ti-rich basalt from 85/sup 0/W represents 19 to 35% residual liquid following crystal fractionation of a mineral assemblage of plagioclase, clinopyroxene, and lesser olivine. Most samples from 85/sup 0/W can be related to a common parental magma that contained approximately 9 wt %FeO*, 1 wt % TiO/sub 2/, and had an Mg number (Mg/sup 3/ = 100 Mg/(Mg+Fe/sup 2 +/)) of about 65. Although the samples from 95/sup 0/W cannot all be derived from a common parental magma, the inferred parental magmas may have been derived by varying degrees of partial melting of a common source. The fractionation sequence consists of two parts: an initial iron enrichment trend followed by a silica enrichment trend. The most iron rich lavas represent about 32% residual liquid derived by crystal fractionation of plagioclase, clinopyroxene, and lesser olivine from a parental magma with an Mg number of about 66. The silicic enrichment trend results from crystallization of titanomagnetite and some apatite.</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 negative? Nd(O) parameter than the other volcanic suite, and a third metasedimentary source with? 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 of? Nd(O) versus? 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 an? Sr(O)-? Nd(O) diagram is the result of varying degrees of contamination of a "primitive arc-type" magma by the Precambrian continental crust of the western Brazilian Shield. The depleted mantle average Nd model age of 1.46 Ga for the fluvial sands reflects the average age of the Brazilian continental crustal source. The development of the Andean orogenic belt has been discussed schematically with the isotopic data of the sands. The model describes a trailing edge prism of sediments, derived from the Brazilian Shield during the late Paleozoic-early Mesozoic. The prism becomes part of the fold-thrust belt during the Andean orogeny in the Neogene, when the foreland basin develops with the basin fill partly derived from the fold-thrust belt. The sedimentary rocks in the fold-thrust belt are also a major source of contaminants for the Andean magmas. The contiguous nature of the Andean magmatic trend and the fluvial sand data in the? Sr(O)-? Nd(O) diagram suggests that the ensialic Andean magmatic arc has remained connected to its parent continent, the western Brazilian Shield, throughout the development of the Andean orogeny.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25000508','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25000508"><span id="translatedtitle">Examination of rare <span class="hlt">earth</span> <span class="hlt">element</span> concentration patterns in freshwater fish tissues.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mayfield, David B; Fairbrother, Anne</p> <p>2015-02-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs or lanthanides) were measured in ten freshwater fish species from a reservoir in Washington State (United States). The REE distribution patterns were examined within fillet and whole body tissues for three size classes. Total concentrations (?REE) ranged from 0.014 to 3.0 mg kg(-1) (dry weight) and averaged 0.243 mg kg(-1) (dry weight). Tissue concentration patterns indicated that REEs accumulated to a greater extent in organs, viscera, and bone compared to muscle (fillet) tissues. Benthic feeding species (exposed to sediments) exhibited greater concentrations of REEs than pelagic omnivorous or piscivorous fish species. Decreasing REE concentrations were found with increasing age, total length or weight for largescale and longnose suckers, smallmouth bass, and walleye. Concentration patterns in this system were consistent with natural conditions without anthropogenic sources of REEs. These data provide additional reference information with regard to the fate and transport of REEs in freshwater fish tissues in a large aquatic system. PMID:25000508</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://adsabs.harvard.edu/abs/2014JMEP..tmp..355L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JMEP..tmp..355L"><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>2014-09-01</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> </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://pubs.er.usgs.gov/publication/70012626','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012626"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> distribution in some hydrothermal minerals: evidence for crystallographic control</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morgan, J.W.; Wandless, G.A.</p> <p>1980-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) abundances were measured by neutron activation analysis in anhydrite (CaSO4), barite (BaSO4), siderite (FeCO3) and galena (PbS). A simple crystal-chemical model qualitatively describes the relative affinities for REE substitution in anhydrite, barite, and siderite. When normalized to 'crustal' abundances (as an approximation to the hydrothermal fluid REE pattern), log REE abundance is a surprisingly linear function of (ionic radius of major cation-ionic radius of REE)2 for the three hydrothermal minerals, individually and collectively. An important exception, however, is Eu, which is anomalously enriched in barite and depleted in siderite relative to REE of neighboring atomic number and trivalent ionic radius. In principle, REE analyses of suitable pairs of co-existing hydrothermal minerals, combined with appropriate experimental data, could yield both the REE content and the temperature of the parental hydrothermal fluid. The REE have only very weak chalcophilic tendencies, and this is reflected by the very low abundances in galena-La, 0.6 ppb; Sm, 0.06 ppb; the remainder are below detection limits. ?? 1980.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('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://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://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://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/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://www.ncbi.nlm.nih.gov/pubmed/26141170','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26141170"><span id="translatedtitle">Template polymerization synthesis of hydrogel and silica composite for sorption of some 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>Borai, E H; Hamed, M G; El-kamash, A M; Siyam, T; El-Sayed, G O</p> <p>2015-10-15</p> <p>New sorbents containing 2-acrylamido 2-methyl propane sulphonic acid monomer onto poly(vinyl pyrilidone) P(VP-AMPS) hydrogel and P(VP-AMPS-SiO2) composite have been synthesized by radiation template polymerization. The effect of absorbed dose rate (kGy), crosslinker concentration and polymer/monomer ratio on the degree of template polymerization of P(VP-AMPS) hydrogel was studied. The degree of polymerization was evaluated by the calculated percent conversion and swelling degree. The maximum capacity of P(VP-AMPS) hydrogel toward Cu(+2) metal ion found to be 91 mg/gm. The polymeric composite P(VP-AMPS-SiO2) has been successfully synthesized. The structure of the prepared hydrogel and composite were confirmed by FTIR, thermal analysis (TGA and DTA) and SEM micrograph. Batch adsorption studies for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(+2) metal ions on the prepared hydrogel and composite were investigated as a function of shaking time, pH and metal ion concentration. The sorption efficiency of the prepared hydrogel and composite toward light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREEs) are arranged in the order La(3+)>Ce(3+)>Nd(3+)>Eu(3+). The obtained results demonstrated the superior adsorption capacity of the composite over the polymeric hydrogel. The maximum capacity of the polymeric composite was found to be 116, 103, 92, 76, 74 mg/gm for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(2+) metal ions respectively. PMID:26141170</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://adsabs.harvard.edu/abs/2009MMTA...40.2190K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009MMTA...40.2190K"><span id="translatedtitle">Effects of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Additions on the Impression Creep Behavior of AZ91 Magnesium Alloy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kabirian, F.; Mahmudi, R.</p> <p>2009-09-01</p> <p>The effects of 1, 2, and 3 wt pct rare <span class="hlt">earth</span> (RE) <span class="hlt">element</span> additions on the microstructure and creep behavior of cast AZ91 Mg alloy were investigated by impression tests. The tests were carried out under constant punching stress in the range 200 to 650 MPa at temperatures in the range 425 to 525 K. Analysis of the data showed that for all loads and temperatures, the AZ91-2RE alloy had the lowest creep rates and, thus, the highest creep resistance among all materials tested. This is attributed to the formation of Al11RE3 with a branched morphology, reduction in the volume fraction of the eutectic ?-Mg17Al12 phase, and solid solution hardening effects of Al in the Mg matrix. The stress exponents and activation energies were the same for all alloy systems studied, 5.3 to 6.5 and 90 to 120 kJ mol-1, respectively, with the exception that the activation energy for the AZ91-3RE system was 102 to 126 kJ mol-1. An observed decreasing trend of creep-activation energy with stress suggests that two parallel mechanisms of lattice and pipe diffusion-controlled dislocation climb are competing. Dislocation climb controlled by dislocation pipe diffusion is controlling at high stresses, whereas climb of edge dislocations is the controlling mechanism at low stresses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010MMTA...41.1973N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010MMTA...41.1973N"><span id="translatedtitle">Effect of Ca and Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> on Impression Creep Properties of AZ91 Magnesium Alloy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nami, B.; Razavi, H.; Mirdamadi, S.; Shabestari, S. G.; Miresmaeili, S. M.</p> <p>2010-08-01</p> <p>Creep properties of AZ91 magnesium alloy and AZRC91 (AZ91 + 1 wt pct RE + 1.2 wt pct Ca) alloy were investigated using the impression creep method. It was shown that the creep properties of AZ91 alloy are significantly improved by adding Ca and rare <span class="hlt">earth</span> (RE) <span class="hlt">elements</span>. The improvement in creep resistance is mainly attributed to the reduction in the amount and continuity of eutectic ?(Mg17Al12) phase as well as the formation of new Al11RE3 and Al2Ca intermetallic compounds at interdendritic regions. It was found that the stress exponent of minimum creep rate, n, varies between 5.69 and 6 for AZ91 alloy and varies between 5.81 and 6.46 for AZRC91 alloy. Activation energies of 120.9 8.9 kJ/mol and 100.6 7.1 kJ/mol were obtained for AZ91 and AZRC91 alloys, respectively. It was shown that the lattice and pipe-diffusion-controlled dislocation climb are the dominant creep mechanisms for AZ91 and AZRC91 alloys, respectively. The constitutive equations, correlating the minimum creep rate with temperature and stress, were also developed for both alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://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/2015RuMet2015..685K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015RuMet2015..685K"><span id="translatedtitle">Sorption from slurries—A promising method in the processing 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>Kosynkin, V. D.; Molchanova, T. V.; Peganov, V. A.; Zharova, E. V.</p> <p>2015-09-01</p> <p>The article presents the results of sorptive extraction of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) from the solutions and slurries of complex salt compositions using sulfocationites and carboxyl cationites with a predominant content of the latter on laboratory and pilot scales. Upon REE sorption from hydrate slurry on KM-2p carboxyl cationite, the REE extraction rate of at least 98% has been achieved, and the following factors of ΣREE purification from impurities have been obtained: K REE/Al = 1.7, K REE/Th = 2.3, K REE/Ca ≈ 20, K REE/Zr = 15, K REE/Fe ≈ 40, and K REE/P,F ≈ 90. It is demonstrated that the REE capacity of cationite SG-1m is higher than that of cationite KM-2p by 10%; moreover, the content of thorium on KM-2p cationite is lower by 2.5 times and that of zirconium by 6 times. After the recovery of saturated cationites by 1.5-2.0 M HNO3 solutions, strippants have been extracted with a REE concentration of 15-20 g/L. The factors of REE purification from impurities upon desorption are as follows: K REE/Al = 2.5, K REE/Th = 0.5, K REE/Ca = 5.3, K REE/Zr = 5.6, and K REE/Fe = 0.8. The REE recovery rate is ≥99%.</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MSMSE..21f5003F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MSMSE..21f5003F"><span id="translatedtitle">Gupta potential for rare <span class="hlt">earth</span> <span class="hlt">elements</span> of the fcc phase: lanthanum and cerium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fu, Jie; Zhao, Jijun</p> <p>2013-09-01</p> <p>The potential parameters for a Gupta-type many-body potential are fitted for the first two rare <span class="hlt">earth</span> <span class="hlt">elements</span>, La and Ce. The experimental cohesive energies, lattice parameters and elastic constants of ?-La and ?-Ce solids of the face-centered cubic (fcc) phase are well reproduced. The theoretical P-V curves, sound velocities and Debye temperatures of ?-La and ?-Ce solids are in reasonable agreement with experimental data. The vacancy formation energies and surface energies are also predicted. In particular, the phonon dispersion relationship and vibrational frequencies at high symmetric points within the first Brillouin zone from our potential are consistent with experimental ones. Molecular dynamics simulation are performed to determine the melting temperature of La and Ce solids as well as the radial distribution function of liquid La, which are also in line with experimental data. All these agreements indicate the validity of the current set of potential parameters. Thus, the Gupta potential developed here would be useful in future simulation of La, Ce solids and their alloys.</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 ?m) were 5-15 times higher than those in four size fractions of zooplankton: 200-500 ?m, 500-1000 ?m, 1000-2000 ?m and >2000 ?m. The concentrations within these zooplankton fractions exhibited the same ranges with some variation attributed to differences in zooplankton taxonomy. The REE concentrations in plankton were poorly related to the reported REE concentrations of seawater, but they correlated well with the calculated REE(3+), concentrations especially with regard to middle REE (MREEs) and heavy REEs (HREEs). Plankton and seawater revealed different PAAS-normalised REE distributions, with the greatest differences observed in the light REEs. Interestingly, a comparison of PAAS-normalized sediment particles from the study of Fowler et al. (1992) showed concentrations of the same order of magnitude and a similar REE distribution without MREE enrichment. Based on this comparison, we propose a conceptual model that emphasizes the importance of biological scavenging of REEs (especially LREEs) in surface waters. PMID:24972173</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6664933','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6664933"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in sediments off southern California: a new Anthropogenic indicator</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Olmez, I. ); Sholkovitz, E.R.; Hermann, D. ); Eganhouse, R.P. )</p> <p>1990-01-09</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) composition of dated sediment cores from the San Pedro Shelf (60 m) and the Santa Barbara Basin (588 m) are contrasted. The Santa Barbara Basin cores has relatively uniform REE concentrations throughout it's 60 cm length and a REE composition similar to the crustal abundance. In contrast, the upper 20 cm of the 36 cm deep San Pedro Shelf core is enriched in the concentrations of the light REE (La, Cd, Nd and Sm) but not in the middle REE (Eu) and the heavy REE (Yb, Lu). These upper sediments have a REE signature which is very different from crustal material and which corresponds to anthropogenic inputs beginning in the early 1960's delivered from the Joint Water Pollution Control Plant wastewater outfall located 6 km upcurrent from the San Pedro Shelf Core. The sources of the light REE enrichment are petroleum cracking catalysts and their products; these include emissions, bottom ash, fly ash and wastewater from oil-burning powerplants and oil-refineries. Cracking catalysts are produced from Bastnasite and Monazite, REE ore minerals strongly enriched in light REE. With their unique signature and source, light REE may be a new tool for tracing anthropogenic inputs to the Santa Monica and San Pedro Basins.</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, ?, is strongly affected by well-known seasonal effects in the discovery rate of NEOs. The deviation from the expected ?-periodicity in the apparent distribution of ? indicates that its intrinsic distribution is slightly enhanced along a mean direction, ??=111; approximately 53% of NEOs have ? values within 90 of ??. 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 ?, and longitudes of perihelion ?. For their intrinsic distributions, our analysis reveals that the Apollo asteroids have non-uniform ? due to secular dynamics associated with inclination-eccentricity-? coupling, and the Amors ? distribution is peaked towards the secularly forced eccentricity vector. The Apollos ? distribution is axial, favoring values near 0 and 180; the two quadrants centered at 0 and 180 account for 55% of the Apollos ? values. The Amors ? distribution peaks near ??=4; 61% of Amors have ? 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 Jupiters. 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.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://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> </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://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://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://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://www.osti.gov/scitech/biblio/6804012','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6804012"><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://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lichte, F.E.; Meier, A.L.; Crock, J.G.</p> <p>1987-04-15</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 metal:metal oxide ratios and sensitivity. Reference standard values are used to verify the accuracy and utility of the method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004Geo....32..497M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004Geo....32..497M"><span id="translatedtitle">Effect of paleosol formation on rare <span class="hlt">earth</span> <span class="hlt">element</span> signatures in fossil bone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Metzger, Christine A.; Terry, Dennis O., Jr.; Grandstaff, David E.</p> <p>2004-06-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) content of fossil bones was analyzed and compared with the degree of ancient pedogenic development and depositional environments from several locations in the Orellan Scenic Member of the Oligocene Brule Formation in Badlands National Park, South Dakota. Paleosols ranged from weakly developed Entisols to more strongly developed Inceptisols, all typical of fluvial environments and possible paleocatena variation. Paleosols were alkaline and well drained. Sediments with sparse soil features from an oxbow lake system suggest that conditions were too waterlogged and sedimentation rates too rapid for significant pedogenesis. The variance of REE signatures in fossil bones from the paleosol sites was significantly greater than that of fossils from minimally altered sediments of the former oxbow lake. Positive Ce anomalies were associated with low U concentrations and indicate paleoredox conditions. Greater degrees of pedogenesis, regardless of the horizon in which the bone was found, systematically correlated with increased heavy REE enrichment in fossil bones. The fossil-bone REE signatures from the different paleosols and depositional environments were significantly different and distinguishable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995SPIE.2373...59K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995SPIE.2373...59K"><span id="translatedtitle">LiYF4 (YLF) single crystals doped with 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>Kowalczyk, E.; Kowalczyk, Z.; Grasza, K.; Gala, M.; Lukasiewicz, Tadeusz</p> <p>1995-10-01</p> <p>LiYF4 (YLF) is a very promising host material for lasers. Investigation of the spectroscopic and physical properties of YLF:Nd has suggested that this material may be a better candidate than Nd:YAG for generating short pulses with high peak power. This is a distinct advantage for many applications. Stimulated emission is attained at 1053 nm and 1047 nm. Also upconservation laser action in YLF and YLF:Er crystals is reported. More recently YLF doped with rare-<span class="hlt">earth</span> <span class="hlt">elements</span> has gained some attention. Pulsed room-temperature laser action at 2.06 micrometer has been achieved using YLF:Ho sensitized with Er and Tm. Using YLF:Pr blue light emission at 479 nm at room temperature was observed. Growth experiments of YLF:Nd crystals were carried by the Bridgman method. A vacuum furnace with cylindrical molybdenum heater and graphite crucible have been used. The temperature gradient of 25 degrees Celsius/cm has been achieved by using a stainless steel liner in the lower part of the furnace. The growth was performed in a nitrogen atmosphere. First crystals of YLF:Nd have been obtained.</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.; Lematre, 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://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://adsabs.harvard.edu/abs/2016NatSR...619961T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...619961T"><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://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 gradients. Furthermore, because the ultraoligotrophic nature of the lake limits the potential for organic phases to act as metal carriers, metal oxide coatings and sulfide phases appear to largely govern the distribution of trace <span class="hlt">elements</span>. We discuss REE cycling in relation to the roles of redox reactions and competitive scavenging onto Mn- and Fe-oxides coatings on clay sized particles in the upper oxic water column and their release by reductive dissolution near the anoxic/oxic interface.</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 meta