Concentration distribution and assessment of several heavy metals in sediments of west-four Pearl River Estuary

NASA Astrophysics Data System (ADS)

Wang, Shanshan; Cao, Zhimin; Lan, Dongzhao; Zheng, Zhichang; Li, Guihai

2008-09-01

Grain size parameters, trace metals (Co, Cu, Ni, Pb, Cr, Zn, Ba, Zr and Sr) and total organic matter (TOM) of 38 surficial sediments and a sediment core of west-four Pearl River Estuary region were analyzed. The spacial distribution and the transportation procession of the chemical element in surficial sediments were studied mainly. Multivariate statistics are used to analyses the interrelationship of metal elements, TOM and the grain size parameters. The results demonstrated that terrigenous sediment taken by the rivers are main sources of the trace metal elements and TOM, and the lithology of parent material is a dominating factor controlling the trace metal composition in the surficial sediment. In addition, the hydrodynamic condition and landform are the dominating factors controlling the large-scale distribution, while the anthropogenic input in the coastal area alters the regional distribution of heavy metal elements Co, Cu, Ni, Pb, Cr and Zn. The enrichment factor (EF) analysis was used for the differentiation of the metal source between anthropogenic and naturally occurring, and for the assessment of the anthropogenic influence, the deeper layer content of heavy metals were calculated as the background values and Zr was chosen as the reference element for Co, Cu, Ni, Pb, Cr and Zn. The result indicate prevalent enrichment of Co, Cu, Ni, Pb and Cr, and the contamination of Pb is most obvious, further more, the peculiar high EF value sites of Zn and Pb probably suggest point source input.

Tools and techniques for developing tephra stratigraphies in lake cores: A case study from the basaltic Auckland Volcanic Field, New Zealand

NASA Astrophysics Data System (ADS)

Hopkins, Jenni L.; Millet, Marc-Alban; Timm, Christian; Wilson, Colin J. N.; Leonard, Graham S.; Palin, J. Michael; Neil, Helen

2015-09-01

Probabilistic hazard forecasting for a volcanic region relies on understanding and reconstructing the eruptive record (derived potentially from proximal as well as distal volcanoes). Tephrostratigraphy is commonly used as a reconstructive tool by cross-correlating tephra deposits to create a stratigraphic framework that can be used to assess magnitude-frequency relationships for eruptive histories. When applied to widespread rhyolitic deposits, tephra identifications and correlations have been successful; however, the identification and correlation of basaltic tephras are more problematic. Here, using tephras in drill cores from six maars in the Auckland Volcanic Field (AVF), New Zealand, we show how X-ray density scanning coupled with magnetic susceptibility analysis can be used to accurately and reliably identify basaltic glass shard-bearing horizons in lacustrine sediments and which, when combined with the major and trace element signatures of the tephras, can be used to distinguish primary from reworked layers. After reliably identifying primary vs. reworked basaltic horizons within the cores, we detail an improved method for cross-core correlation based on stratigraphy and geochemical fingerprinting. We present major and trace element data for individual glass shards from 57 separate basaltic horizons identified within the cores. Our results suggest that in cases where major element compositions (SiO2, CaO, Al2O3, FeO, MgO) do not provide unambiguous correlations, trace elements (e.g. La, Gd, Yb, Zr, Nb, Nd) and trace element ratios (e.g. [La/Yb]N, [Gd/Yb]N, [Zr/Yb]N) are successful in improving the compositional distinction between the AVF basaltic tephra horizons, thereby allowing an improved eruptive history of the AVF to be reconstructed.

The petrogenesis of island arc basalts from Gunung Slamet volcano, Indonesia: Trace element and 87Sr /86Sr contraints

NASA Astrophysics Data System (ADS)

Vukadinovic, Danilo; Nicholls, Ian A.

1989-09-01

Selected major and trace elements, rare earth element (REE) and 87Sr /86Sr data are presented for arc basalts from Gunung Slamet volcano, Java, Indonesia. On the basis of stratigraphy, trace element content, Zr/Nb, and 87Sr /86Sr ratios, Slamet basalts can be broadly categorized into high abundance magma (HAM) and low abundance magma (LAM) types. Provided the quantities of 'immobile' trace elements (in aqueous systems) such as Nb, Hf and Zr in the mantle wedge and ensuing magmas are unaffected by additions from subducted lithosphere or overlying arc crust, a model may be developed whereby LAM are generated by higher degrees of melting in the mantle wedge (13%) compared to HAM (7%). Hf/Nb or Zr/Nb ratio systematics indicate that prior to metasomatism by the underlying lithosphere, the Slamet mantle wedge was similar in chemical character to transitional-MORB source mantle. Conversely, examination of immobile/mobile incompatible trace element ratios (IMITER) provide clues to the nature of the metasomatizing agent, most likely derived from the subducted slab (basalts and sediments). HAM have constant IMITER ( e.g.Nb/U, Zr/K), whereas LAM show a negative correlation between IMITER and 87Sr /86Sr . Metasomatism of the mantle wedge was modelled by interaction with either a slab-derived-melt or -aqueous fluid. Yb/Sr and 87Sr /86Sr ratios from Slamet basalts and oceanic sediments suggest that 'bulk' mixing of the latter into the mantle wedge is unlikely. Instead, sediments probably interact with overlying mantle in the same way that subducted basalts do-either as melts or fluids. In the case of slab-derived melts mixing with 'pristine' mantle, good agreement with back-calculated values for HAM and LAM sources can be achieved only if a residual phase such as rutile persists in the subducting lithosphere. In the case of fluids, excellent agreement with back-calculated values is obtained for all elements except heavy REE. It is tentatively suggested that aqueous slab-derived fluids, relatively rich in mobile incompatible elements, are the probable metasomatizing agent responsible for the chemical characteristics, particularly low IMITER, of Slamet and other island arc basalts (IAB). Because the mobilities/solubilities of Sr in high pressure and temperature fluids are poorly known, the modelled subduction fluids are not necessarily efficient at raising 87Sr /86Sr in the overlying mantle wedge. As a result, positive correlations between e.g.Ba/La vs. 87Sr /86Sr need not be observed in arc suites, especially if the relative mobilities of Sr, Ba, and La are dependent upon intensive parameters during metasomatism. Assimilation of arc crust by uprising magmas (up to ~14% of crustal Sr) can account for the range of 87Sr /86Sr in HAM. However, calculating the amounts of arc crustal assimilation by uprising magmas is poorly constrained since such modelling is highly dependent upon previous estimates of the degree of metasomatism undergone by the mantle wedge.

Trace element zoning as a record of chemical disequilibrium during garnet growth

NASA Astrophysics Data System (ADS)

Chernoff, Carlotta B.; Carlson, William D.

1999-06-01

Trace element concentrations in pelitic garnets from the Picuris Range of New Mexico display precipitous changes coincident with abrupt variations in Ca concentration. These patterns probably arise from the transitory participation of different trace element enriched phases in the garnet forming reaction. Changes in the reactant and product assemblages occur at different times during the reaction history for crystals of different size, so they cannot be the result of any event affecting the entire rock, such as a change in pressure, temperature, or fluid composition. Instead, they reflect kinetic factors that cause Ca, Y, Yb, P, Ti, Sc, Zr, Hf, Sr, Na, and Li to fail to achieve chemical equilibrium during garnet growth. Caution is needed to avoid misinterpreting excursions in the concentration of these elements as event markers recording simultaneous rockwide changes in intensive parameters, when in fact they may record transient disequilibrium states that are local in scope, and not contemporaneous.

Relationships among multiple trace elements in coastal Casuarina equisetifolia ecosystems on Hainan Island, South China.

PubMed

Liu, Qiang; Bi, Hua; Hung, Lan; Peng, Shaolin; Sheng, Chengde

2006-01-01

Forty-six trace elements in coastal Casuarina equisetifolia plant-soil systems at nine sampling sites on Hainan Island were analyzed using ICP-MS. The relationships among the trace elements of the same group or the same periodicity of the Periodic Table in the plants and soils were complex and no consistent patterns were found. More combinations of elements occurred with high positive correlation coefficients within the same periodicity than within the same group of the Periodic Table, and there were more high positive correlations in soils than in plants. However, there were many element combinations in Block d (transition elements) with high positive correlation coefficients in plants. Markedly high positive correlation coefficients between individual rare earth elements and Y and among Zr, Nb, Cd existed in both plants and soils. The dendrograms obtained by cluster analysis show that rare earth elements had very similar occurrence and distribution in both soils and plants. Thus, they behaved as a coherent group of elements both geochemically and biogeochemically. The transition elements were more coherent in plants than in soils.

Rare earth element selenochemistry of immiscible liquids and zircon at Apollo 14 - An ion probe study of evolved rocks on the moon

NASA Technical Reports Server (NTRS)

Snyder, Gregory A.; Taylor, Lawrence A.; Crozaz, Ghislaine

1993-01-01

Results are presented of trace-element analyses of three lunar zircons. The major-element and REE compositions were determined using electron microprobes, and a correction was made for zircon for Zr-Si-O molecular interferences in the La to Pr mass region. The three zircons were found to exhibit similar REE abundances and patterns. Results of the analyses confirm earlier studies (Hess et al., 1975; Watson, 1976; Neal and Taylor, 1989) on the partitioning behavior of trace elements in immiscible liquid-liquid pairs. The results also support the postulated importance of silicate liquid immiscibility in the differentiation of the upper mantle and crust of the moon.

Trace element fractionation and transport in boreal rivers and soil porewaters of permafrost-dominated basaltic terrain in Central Siberia

NASA Astrophysics Data System (ADS)

Pokrovsky, O. S.; Schott, J.; Dupré, B.

2006-07-01

The chemical status of ˜40 major and trace elements (TE) and organic carbon (OC) in pristine boreal rivers draining the basaltic plateau of Central Siberia (Putorana) and interstitial solutions of permafrost soils was investigated. Water samples were filtered in the field through progressively decreasing pore size (5 μm → 0.22 μm → 0.025 μm → 10 kDa → 1 kDa) using cascade frontal filtration technique. Most rivers and soil porewaters exhibit 2-5 times higher than the world average concentration of dissolved (i.e., <0.22 μm) iron (0.03-0.4 mg/L), aluminum (0.03-0.4 mg/L), OC (10-20 mg/L) and various trace elements that are usually considered as immobile in weathering processes (Ti, Zr, Ga, Y, REEs). Ultrafiltration revealed strong relationships between concentration of TE and that of colloidal Fe and Al. According to their partition during filtration and association with colloids, two groups of elements can be distinguished: (i) those weakly dependent on ultrafiltration and that are likely to be present as truly dissolved inorganic species (Li, Na, K, Si, Mn, Mo, Rb, Cs, As, Sb) or, partially (20-30%) associated with small size Fe- and Al-colloids (Ca, Mg, Sr, Ba) and to small (<1-10 kDa) organic complexes (Co, Ni, Cu, Zn), and (ii) elements strongly associated with colloidal iron and aluminum in all ultrafiltrates largely present in 1-100 kDa fraction (Ga, Y, REEs, Pb, V, Cr, Ti, Ge, Zr, Th, U). TE concentrations and partition coefficients did not show any detectable variations between different colloidal fractions for soil porewaters, suprapermafrost flow and surface streams. TE concentration measurements in river suspended particles demonstrated significant contribution (i.e., ⩾30%) of conventionally dissolved (<0.22 μm) forms for usually "immobile" elements such as divalent transition metals, Cd, Pb, V, Sn, Y, REEs, Zr, Hf, Th. The Al-normalized accumulation coefficients of TE in vegetation litter compared to basalts achieve 10-100 for B, Mn, Zn, As, Sr, Sn, Sb, and the larch litter degradation is able to provide the major contribution to the annual dissolved flux of most trace elements. It is hypothesized that the decomposition of plant litter in the topsoil horizon leads to Fe(III)-, Al-organic colloids formation and serves as an important source of elements in downward percolating fluids.

Preliminary examination of the Yamato-86032 lunar meteorite. II - Major and trace element chemistry

NASA Technical Reports Server (NTRS)

Koeberl, Christian; Warren, Paul H.; Lindstrom, Marilyn M.; Spettel, Bernhard; Fukuoka, Takaaki

1989-01-01

Results of the chemical composition analysis of Yamato-86032, found in Antarctica in 1986, are summarized. The meteorite may be classified as an anorthositic breccia, but its trace element composition is different from the composition of the other known lunar meteorites. The major element chemistry of Y-86032 is similar to the other lunar meteorites, except for the iron content, which is lower by a factor of about 1.4. The abundances of incompatible and lithophile elements such as Zr, Hf, Ta, Th, or the REEs are very low and comparable to Y-82192/3. Other elements, in particular Fe, Ti, Sc, Cr, Mn, and Co, have lower abundances in Y-86032 than in Y-82192/3. Variations between individual analysis demonstrate that the rock itself is heterogeneous.

Isotopic Composition of Molybdenum and Barium in Single Presolar Silicon Carbide Grains of Type A+B

NASA Technical Reports Server (NTRS)

Savina, M. R.; Tripa, C. E.; Pellin, M. J.; Davis, A. M.; Clayton, R. N.; Lewis, R. S.; Amari, S.

2003-01-01

Presolar SiC grains fall into several groups based on C, N, and Si isotopic compositions. Approximately 93% are defined as mainstream, having 10 less than C-12/C-13 less than 100 and N-14/N-15 ranging from 50 to 20,000. A number of studies have shown that the most likely sources of mainstream grains are low mass asymptotic giant branch stars. Models of nucleosynthesis in AGB stars reproduce the s-process enhancements seen in the heavy elements in mainstream SiC grains. Among the less common grains, A+B grains, which comprise approximately 3-4% of presolar SiC, are perhaps the least well understood. Recent studies by Amari et al. show that A+B grains can be divided into at least 4 groups based on their trace element concentration patterns. Of 20 grains studied, 7 showed trace element patterns consistent with condensation from a gas of solar system composition, while the rest had varying degrees of process enhancements. Our previous measurements on 3 A+B grains showed Mo of solar isotopic composition, but Zr with a strong enhancement in 96Zr, which is an r-process isotope but can be made in an sprocess if the neutron density is high enough to bridge the unstable Zr-95 (T(sub 1/2)= 64 d). The observation of Mo with solar system isotopic composition in the same grains is puzzling however. Meyer et al. have recently shown that a neutron burst mechanism can produce a high Zr-96/Zr-94 without enhancing Mo-100, however this model leads to enhancements in Mo-95 and Mo-97 not observed in A+B grains. We report here results of Mo measurements on 7 additional A+B grains, and Ba measurements on 2 A+B grains, and compare these to the previous studies.

Importance of nanoparticles and colloids from volcanic ash for riverine transport of trace elements to the ocean: evidence from glacial-fed rivers after the 2010 eruption of Eyjafjallajökull Volcano, Iceland.

PubMed

Tepe, Nathalie; Bau, Michael

2014-08-01

Volcanic ashes are often referenced as examples for natural nanoparticles, yet the particle size distribution <1000 nm is only rarely documented. We here report results of a geochemical study of glacial-fed rivers, glacial surface runoff, glacial base flow, and pure glacial meltwater from southern Iceland, that had been sampled 25 days after the explosive eruptions at Eyjafjallajökull in 2010. In addition to the dissolved concentrations of rare earth elements (REE), Zr, Hf, Nb, and Th in the 450 nm-filtered waters, we also studied the respective filter residues (river particulates >450 nm) and volcanic ash. In spite of the low solubilities and high particle-reactivities of the elements studied, most water samples show high dissolved concentrations, such as up to 971 ng/kg of Ce and 501 ng/kg of Zr. Except for the pure glacial meltwater and glacial base flow, all waters display the same shale-normalized REE patterns with pronounced light and heavy REE depletion and positive Eu anomalies. While such patterns are unusual for river waters, they are similar to those of the respective river particulates and the volcanic ash, though at different concentration levels. The distribution of dissolved Zr, Hf, Nb, and Th in the waters also matches that of filter residues and ash. This strongly suggests that in all 450 nm-filtered river waters, the elements studied are associated with solid ash particles smaller than 450 nm. This reveals that volcanic ash-derived nanoparticles and colloids are present in these glacial-fed rivers and that such ultrafine particles control the trace element distribution in the surface runoff. Subsequent to explosive volcanic eruptions, these waters provide terrigenous input from landmasses to estuaries, that is characterized by a unique trace element signature and that subsequent to modification by estuarine processes delivers a pulse of nutrients to coastal seawater in regions not affected by plume fall-out. Copyright © 2014 Elsevier B.V. All rights reserved.

Trace element partitioning between coexisting biotite and muscovite from metamorphic rocks, western Labrador: Structural, compositional and thermal controls

NASA Astrophysics Data System (ADS)

Yang, Panseok; Rivers, Toby

2000-04-01

Coexisting biotite and muscovite in ten metapelitic and quartzofeldspathic rocks from western Labrador have been analyzed by electron microprobe for major and minor elements and by a laser ablation microprobe coupled to ICP-MS (LAM-ICP-MS) for selected trace elements - Li, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Hf and Ta. The samples have experienced a single prograde Grenvillian metamorphism ranging from 490 to 680°C and from 7 to 12 kbar. The trace element compositions of coexisting micas in the metamorphic rocks are used to assess the effects of crystal structure, major element composition and temperature on the partitioning of each element between biotite and muscovite. Overall, trace element distributions are systematic across the range of metamorphic grade and bulk composition, suggesting that chemical equilibrium was approached. Most distribution coefficients (biotite/muscovite) show good agreement with published data. However, distribution coefficients for Co and Sr are significantly different from previous determinations, probably because of contamination associated with older data obtained by bulk analysis techniques. The sequence of distribution coefficients is governed mainly by the ionic radii and charges of substituting cations compared to the optimum ionic radius of each crystallographic site in the micas. In particular, distribution coefficients exhibit the sequence Cr 3+ (0.615 Å) > V 3+ (0.64 Å) > Sc 3+ (0.745 Å) in VI-sites, and Ba 2+ (1.61 Å) > Sr 2+ (1.44 Å) and Cs + (1.88 Å) > K + (1.64 Å) > Rb + (1.72 Å) > Na + (1.39 Å) in XII-sites. The distributions of Li, Sc, Sr and Ba appear to be thermally sensitive but are also controlled by major element compositions of micas. V and Zr partitioning is dependent on T and may be used to cross-check thermometry calculations where the latter suffer from retrograde re-equilibration and/or high concentrations of Fe 3+. The ranges and dependence of distribution coefficients on major element compositions provide important constraints on the values that can be used in geochemical modeling.

An experimental study of trace element partitioning between perovskite, hibonite and melt: Equilibrium values

NASA Technical Reports Server (NTRS)

Kennedy, A. K.; Lofgren, G. E.; Wasserburg, G. J.

1993-01-01

The presence of perovskite (CATiO3) and hibonite (Ca Al12O19) within different regions of Calcium-, Aluminum-rich Inclusions (CAI) and the trace element concentrations of these minerals in each circumstance, constrain models of precursor formation, nebular condensation, the thermal history of inclusions with relict perovskite and hibonite, and the formation of the Wark-Lovering rim. At present mineral/melt partition coefficient data for hibonite are limited to a few elements in simple experimental systems, or to those derived from hibonite-glass pairs in hibonite/glass microspherules. Similarly, there is only limited data on perovskite D that are applicable to meteorite compositions. Apart from the importance of partitioning studies to meteorite research, D values also are invaluable in the development of thermodynamic models, especially when data is available for a large number of elements that have different ionic charge and radii. In addition, study of the effect of rapid cooling on partitioning is crucial to our understanding of meteorite inclusions. To expand our knowledge of mineral/melt D for perovskite and hibonite, a study was instituted where D values are obtained in both equilibrium and dynamic cooling experiments. As an initial phase of this study mineral/melt D was measured for major elements (Ca, Mg, Al, Ti, and Si), 15 rare earth elements (La-Lu) and 8 other elements (Ba, Sr, U, Th, Nb, Zr, Hf, and Ge) in perovskite and hibonite grown under equilibrium conditions, in bulk compositions that are respectively similar to Compact Type A (CTA) CAI and to a hibonite/glass microspherule. Experimental mixes were doped with REE at 20-50x chondritic (ch) abundances, Ba at 50 ppm, Sr, Hf, Nb, and Zr at 100 ppm and, U and Th at 200 ppm. Trace element abundances were measured with the PANURGE ion microprobe. Major element compositions were obtained by electron microprobe analysis.

Provenance and paleoweathering reconstruction of the Mesoproterozoic Hongshuizhuang Formation (1.4 Ga), northern North China

NASA Astrophysics Data System (ADS)

Luo, Qingyong; Zhong, Ningning; Wang, Yannian; Ma, Ling; Li, Min

2015-10-01

This is the first study presenting major and trace elemental data from the Mesoproterozoic Hongshuizhuang Formation shales in Yanshan basin, North China, in order to reconstruct its provenance and chemical weathering history. The shales are strongly depleted in Na2O and Sr and enriched in Y and transition metal elements relative to upper continental crust. Low Zr concentrations and various discriminant plots (e.g., Th/Sc-Zr/Sc and Al2O3-TiO2-Zr) indicate insignificant mineral sorting or recycling of these shales. The rocks show light rare earth element (REE) enrichment (La/YbCN = 3.99-6.92), flat heavy REE, and significantly negative Eu anomalies (Euan = 0.57-0.68) in chondrite-normalized REE patterns, similar to post-Archean Australian average shales. The fairly uniform REE patterns and trace element ratios indicate that the Hongshuizhuang Formation shales were derived from a felsic source area with granodiorite as the dominant contributor. Mixing calculations suggest a mixture of 30 % granite porphyry, 5 % basalt, and 65 % granodiorite as the possible source of the shales, also supporting that granodiorite was the predominant source. Intense chemical weathering of the source terrain is indicated by high values of the premetasomatized chemical index of alteration, plagioclase index of alteration, Rb/Sr, a strong positive correlation between TiO2 and Al2O3, depletion of CaO, Na2O, and Sr, and mineral compositions. Such strong chemical weathering suggests a warm and wet paleoclimate, perhaps due to high atmospheric CO2 and CH4 concentrations, and a near-equatorial location of the North China Craton in the Columbia supercontinent at 1.4 Ga.

Obsidian provenance determination by using the beam stability controlled BSC-XRF and the PIXE-alpha portable spectrometers of the LANDIS laboratory of the LNS-INFN and IBAM-CNR in Catania (Italy)

NASA Astrophysics Data System (ADS)

Pappalardo, L.; Bracchitta, D.; Palio, O.; Pappalardo, G.; Rizzo, F.

2012-04-01

About 1300 obsidian artefacts coming from various archaeological sites of Sicily were analyzed by using the BSC-XRF (Beam Stability Controlled - X-ray Fluorescence) and PIXE-alpha (Particle Induced X-ray Emission, using low energy alpha particles) portable spectrometers developed at the Landis laboratory at the LNS-INF and IBAM-CNR in Catania (Italy). The portable BSC-XRF system allows the non-destructive analysis of the Rb, Sr, Y, Zr and Nb trace concentrations, which are considered to be characteristic of the obsidian samples and consequently are indicative of the provenance quarries. Quantitative data on Rb, Sr, Y, Zr, Nb trace element concentrations where deduced through the use of a method that makes use of a multi parameter linear regression, previously The portable PIXE-alpha spectrometer allows the quantitative determination of the matrix major elements, from Na to Zn. In the present work the two instrumental devices are presented. The data are from: Milena (Cl), Ustica (Pa), Rocchicella (Ct), Poggio dell'Acquila (Ct), San Marco (Ct), Villaggio del Petraro* (Sr) and Licodia Eubea* (Ct). Results on compositional data for trace elements and major elements allowed to identify Lipari and Pantelleria islands as the only two sources of the analysed samples. Analyses carried out on vitreous artefact found in Rocchicella, showed for the first time that the Palagonite was used as row material. *Preliminary data. Topic of conference: Application of XRS in archaeometry Kind of presentation: oral

Distribution of major and trace elements in surface sediments of the western Gulf of Thailand: Implications to modern sedimentation

NASA Astrophysics Data System (ADS)

Liu, Shengfa; Shi, Xuefa; Yang, Gang; Khokiattiwong, Somkiat; Kornkanitnan, Narumol

2016-04-01

In this study, we analyze major and trace elements (SiO2, Al2O3, Fe2O3, CaO, K2O, MgO, Na2O, TiO2, P2O5, MnO, Cu, Pb, Ba, Sr, V, Zn, Co, Ni, Cr, and Zr) and grain size of 157 surface sediment samples from the western Gulf of Thailand (GoT). On the basis of the space distribution characteristics, the study area can be classified into three geochemical provinces. Province I covers the northern and northwestern coastal zones of the GoT, including the whole upper GoT and thus the sediments from the rivers in the area. It contains high contents of SiO2. Province II is located in the middle of the GoT and has similar geochemistry composition as the South China Sea (SCS). It contains sediments that are characterized by higher contents of Na2O, TiO2, Ba, Cr, V, Zn, Zr, and Ni. Province Ш is located in the lower GoT, close to Malaysia. Major and trace elements in this area showed complex distribution patterns, which may be due to terrestrial materials from Malay rivers combining with some sediments from the SCS in this province. The results also indicate that grain size is the controlling factor in elemental contents, and that the hydrodynamic environment and mineral composition of the sediments play an important role in the distribution of these elements. The anthropogenic impact of heavy metal introduction (especially Cr, Zn, Cu, and Pb) can be seen in surface sediments from the nearshore region of Chantaburi province and north of Samui Island.

Diffusive exchange of trace elements between alkaline melts: Implications for element fractionation and timescale estimations during magma mixing

NASA Astrophysics Data System (ADS)

González-Garcia, Diego; Petrelli, Maurizio; Behrens, Harald; Vetere, Francesco; Fischer, Lennart A.; Morgavi, Daniele; Perugini, Diego

2018-07-01

The diffusive exchange of 30 trace elements (Cs, Rb, Ba, Sr, Co, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ta, V, Cr, Pb, Th, U, Zr, Hf, Sn and Nb) during the interaction of natural mafic and silicic alkaline melts was experimentally studied at conditions relevant to shallow magmatic systems. In detail, a set of 12 diffusion couple experiments have been performed between natural shoshonitic and rhyolitic melts from the Vulcano Island (Aeolian archipelago, Italy) at a temperature of 1200 °C, pressures from 50 to 500 MPa, and water contents ranging from nominally dry to ca. 2 wt.%. Concentration-distance profiles, measured by Laser Ablation ICP-MS, highlight different behaviours, and trace elements were divided into two groups: (1) elements with normal diffusion profiles (13 elements, mainly low field strength and transition elements), and (2) elements showing uphill diffusion (17 elements including Y, Zr, Nb, Pb and rare earth elements, except Eu). For the elements showing normal diffusion profiles, chemical diffusion coefficients were estimated using a concentration-dependent evaluation method, and values are given at four intermediate compositions (SiO2 equal to 58, 62, 66 and 70 wt.%, respectively). A general coupling of diffusion coefficients to silica diffusivity is observed, and variations in systematics are observed between mafic and silicic compositions. Results show that water plays a decisive role on diffusive rates in the studied conditions, producing an enhancement between 0.4 and 0.7 log units per 1 wt.% of added H2O. Particularly notable is the behaviour of the trivalent-only REEs (La to Nd and Gd to Lu), with strong uphill diffusion minima, diminishing from light to heavy REEs. Modelling of REE profiles by a modified effective binary diffusion model indicates that activity gradients induced by the SiO2 concentration contrast are responsible for their development, inducing a transient partitioning of REEs towards the shoshonitic melt. These results indicate that diffusive fractionation of trace elements is possible during magma mixing events, especially in the more silicic melts, and that the presence of water in such events can lead to enhanced chemical diffusive mixing efficiency, affecting also the estimation of mixing to eruption timescales.

The Pasamonte unequilibrated eucrite: Pyroxene REE systematic and major-, minor-, and trace-element zoning. [Abstract only

NASA Technical Reports Server (NTRS)

Pun, A.; Papike, J. J.

1994-01-01

We are evaluating the trace-element concentrations in the pyroxenes of Pasamonte. Pasamonte is a characteristic member of the main group eucrites, and has recently been redescribed as a polymict eucrite. Our Pasamonte sample contained eucritic clasts with textures ranging from subophitic to moderately coarse-grained. This study concentrates on pyroxenes from an unequilibrated, coarse-grained eucrite clast. Major-, minor-, and trace-element analyses were measured for zoned pyroxenes in the eucritic clast of Pasamonte. The major- and minor-element zoning traverses were measured using the JEOL 733 electron probe with an Oxford-Link imaging/analysis system. Complemenatry trace elements were then measured for the core and rim of each of the grains by SIMS. The trace elements analyzed consisted of eight REE, Sr, Y, and Zr. These analyses were performed on a Cameca 4f ion probe. The results of the CI chondrite normalized (average CI trace-element analyses for several grains and the major- and minor-element zoning patterns from a single pyroxene grain are given. The Eu abundance in the cores of the pyroxenes represents the detection limit and therefore the (-Eu) anomaly is a minimum. Major- and minor-element patterns are typical for igneous zoning. Pyroxene cores are Mg enriched, whereas the rims are enriched in Fe and Ca. Also, Ti and Mn are found to increase, while Cr and Al generally decrease in core-to-rim traverses. The cores of the pyroxenes are more depleted in the Rare Earth Elements (REE) than the rims. Using the minor- and trace-element concentrations of bulk Pasamonte and the minor- and trace-element concentrations from the cores of the pyroxenes in Pasamonte measured in this study, we calculated partition coefficients between pyroxene and melt. This calculation assumes that bulk Pasamonte is representative of a melt composition.

Major, minor, trace and rare earth elements in sediments of the Bijagós archipelago, Guinea-Bissau.

PubMed

Carvalho, Lina; Figueira, Paula; Monteiro, Rui; Reis, Ana Teresa; Almeida, Joana; Catry, Teresa; Lourenço, Pedro Miguel; Catry, Paulo; Barbosa, Castro; Catry, Inês; Pereira, Eduarda; Granadeiro, José Pedro; Vale, Carlos

2018-04-01

Sixty sediment samples from four sites in the Bijagós archipelago were characterized for fine fraction, loss on ignition, major, minor and trace elemental composition (Al, Fe, Ca, Mg, Ti, P, Zr, Mn, Cr, Sr, Ba, B, V, Li, Zn, Ni, Pb, As, Co, U, Cu, Cs and Cd), and the elements of the La-Lu series. Element concentrations were largely explained by the Al content and the proportion of fine fraction content, with the exception of Ca and Sr. Sediments showed enhanced Ti, U, Cr, As and Cd concentrations with respect to estimated upper crust values, most likely mirroring a regional signature. Rare earth elements were in deficit relatively to the North American Shale Composite (NASC), mainly in coarser material. No pronounced Ce-anomaly was observed, while Eu-anomalies were positive in most analyzed sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Trace Element Geochemistry as a Tool for the Reconstruction of Upwelling Patterns at 12oS off Peru since the Last Glacial Maximum (LGM)

NASA Astrophysics Data System (ADS)

Boening, P.; Brumsack, H.; Wolf, A.

2002-05-01

Laminated sediments (core 106KL), recovered during R/V Sonne cruise 147 from the Peruvian upper slope mud lens at 12oS, were analyzed for bulk parameters (TOC, TIC, TS) and opal as well as major and trace element composition by XRF and ICP-MS in 5 cm intervals. The composition of the terrigenous-detrital sediment fraction is comparable to average shale. The sediments exhibit slight increases in biogenic silica (diatoms) and carbonate contents (foraminifera) in varying layers. The experimentally determined opal contents correlate well with Si/Al ratios. High TOC and P contents are due to enhanced primary productivity, high sedimentation rates and corresponding organic matter preservation under a strong OMZ. We distinguish between three different groups of elements: 1.) trace elements involved in bio-cycling (e.g. Cd, Ag, Ni, Cu) are highly enriched in the sediments due to their association with plankton, high sedimentation rates (preventing remobilization from the sediments) and fixation as sulfides. 2.) redox-sensitive elements (e.g. Re, Mo) are significantly enriched probably due to reduction and precipitation under suboxic/anoxic conditions. Diffusion of these elements from the water column into sub/anoxic sediments seems to be the controlling factor, besides sulfide precipitation. An average Re/Mo ratio of 1.3 indicates anoxic sedimentary conditions. Most trace elements correlate well with the TOC content presumably documenting productivity events. 3.) Al, Zr and Y are well correlated, presumably representing sporadic high-energy fluvial input from the continent or enhanced current velocities. The three element groups were used to reconstruct the upwelling patterns off Lima since the LGM: TOC content and Al-normalized trace element patterns from the bio/redox-sensitive fractions represent the signal from the water column, whereas Al, Y and Zr reflect the terrigenous input. During the LGM (about 17 ky BP) the site was hardly affected by upwelling as the upwelling cell was located more basinward. As the sea level rose during the Late Glacial (17-10 ky BP) the upwelling cell shifted towards the coast. The Early Holocene (10-5 ky BP) is not documented likely because strong currents (presumably the Peru counter current) eroded the slope. In the Late Holocene the upwelling cell was established at the site. However, a higher terrrigenous proportion and lower input from the water column suggest a basinward shifting of the upwelling cell during the Second Neoglacial (2000-2700 BP). Stronger Element/Al and TOC variabilities indicate the influence of El Nino during the Late Holocene.

Experimental evidence for mobility of Zr and other trace elements in soils

NASA Astrophysics Data System (ADS)

Hodson, Mark E.

2002-03-01

A Soxhlet extraction was carried out over a period of 27 d on a column comprising 3 cm of quartz overlain by 4 cm of soil from the B horizon and then 1 cm of soil from the A horizon of a granitic podzol. Major and trace elements were leached from the column and accumulated in a reservoir at the base of the column. Total loss of elements from the soil over the course of the experiment ranged from 0.002 to 1 wt% with major elements and the light and heavy rare earth elements (REE) showing the largest percentage losses. Zirconium (0.002%) and then Al (0.008%) showed the lowest percentage loss. The light REE were leached out of the soil preferentially to the mid REE. All elements showed accumulation, by a factor of 2 to 11, in the quartz layers at the base of the column, particularly in the upper first 1 cm of the quartz. Major elements were leached from the column at a rate of 0.02 to 0.59 μmol h-1 whereas Zr, Nd, Sm, Gd, Dy, Rb, and Sr were leached at the rate of 0.5 to 30 × 10-6 μmol h-1. Concentrations of other REE in the reservoir increased over the duration of the experiment, but they were poorly correlated with time, so leaching rates were not calculated. Normalization of the major element leaching rates to take into account the constant flushing of water through the column, the average annual rainfall in the Allt a'Mharcaidh catchment in Scotland from where the soil was sampled, and the cross-sectional area of the soil in the column, together with the temperature of the soil in the column (70°C) compared with the average annual temperature of the Allt a'Mharcaidh catchment (5.7°C), gave major element release rates from the soil of 0.002 to 0.97 mEq m-2 yr-1 (depending on the choice of Ea, the dissolution activation energy), which are generally less than those measured in the field of 0.1 to 40.9 mEq m-2 yr-1. Calculations showed that despite the redistribution and loss of Zr from the column, assumptions of Zr mobility would have had a negligible effect on calculated element release rates of Na, Ca, Fe, and Mg. However, significant underestimates of the release of K (5%), Ti (57%), Al (5%), and Si (10%) as well as some trace elements (e.g., Nd, 23%; Rb, 54%; Sr, 24%) would have occurred. Concentrations of Ca and Sr leached from the column correlated well (RSQ = 0.93, p < 0.01), supporting the idea of the use of Sr release as a proxy for Ca release in weathering rate calculations. The release rates and percentage loss of REE from the soil varied between elements indicating that REE distribution patterns of rocks and soils may not be preserved in drainage waters.

Petrogenesis of Late Cretaceous lava flows from a Ceno-Tethyan island arc: The Raskoh arc, Balochistan, Pakistan

NASA Astrophysics Data System (ADS)

Siddiqui, Rehanul Haq; Qasim Jan, M.; Asif Khan, M.

2012-10-01

The Raskoh arc is about 250 km long, 40 km wide and trends in an ENE direction. The oldest rock unit in the Raskoh arc is an accretionary complex (Early to Late Jurassic), which is followed in age by Kuchakki Volcanic Group, the most wide spread unit of the Raskoh arc. The Volcanic Group is mainly composed of basaltic to andesitic lava flows and volcaniclastics, including agglomerate, volcanic conglomerate, breccia and tuff, with subordinate shale, sandstone, limestone and chert. The flows generally form 3-15 m thick lenticular bodies but rarely reach up to 300 m. They are mainly basaltic-andesites with minor basalts and andesites. The main textures exhibited by these rocks are hypocrystalline porphyritic, subcumulophyric and intergranular. The phenocrysts comprise mainly plagioclase (An30-54 in Nok Chah and An56-64 in Bunap). They are embedded in a micro-cryptocrystalline groundmass having the same minerals. Apatite, magnetite, titanomagnetite and hematite occur as accessory minerals. Major, trace and rare earth elements suggest that the volcanics are oceanic island arc tholeiites. Their low Mg # (42-56) and higher FeO (total)/MgO (1.24-2.67) ratios indicate that the parent magma of these rocks was not directly derived from a mantle source but fractionated in an upper level magma chamber. The trace element patterns show enrichment in LILE and depletion in HFSE relative to N-MORB. Their primordial mantle-normalized trace element patterns show marked negative Nb anomalies with positive spikes on K, Ba and Sr which confirm their island arc signatures. Slightly depleted LREE to flat chondrite normalized REE patterns further support this interpretation. The Zr versus Zr/Y and Cr versus Y studies show that their parent magma was generated by 20-30% melting of a depleted mantle source. The trace elements ratios including Zr/Y (1.73-3.10), Ti/Zr (81.59-101.83), Ti/V (12.39-30.34), La/YbN (0.74-2.69), Ta/Yb (0.02-0.05) and Th/Yb (0.11-0.75) of the volcanics are more consistent with oceanic island arcs rather than continental margin arcs. It is suggested that the Raskoh arc is an oceanic island arc which formed due to the intra-oceanic convergence in the Ceno-Tethys during the Late Cretaceous rather than constructed on the southern continental margin of the Afghan block, as claimed by previous workers. It is further suggested that the Semail, Zagros, Chagai-Raskoh, Muslim Bagh, and Waziristan island arcs were developed in a single but segmented Cretaceous Ceno-Tethyan convergence zone.

Trace element abundances in major minerals of Late Permian coals from southwestern Guizhou province, China

USGS Publications Warehouse

Zhang, Jiahua; Ren, D.; Zheng, C.; Zeng, R.; Chou, C.-L.; Liu, J.

2002-01-01

Fourteen samples of minerals were separated by handpicking from Late Permian coals in southwestern Guizhou province, China. These 14 minerals were nodular pyrite, massive recrystallized pyrite, pyrite deposited from low-temperature hydrothermal fluid and from ground water; clay minerals; and calcite deposited from low-temperature hydrothermal fluid and from ground water. The mineralogy, elemental composition, and distribution of 33 elements in these samples were studied by optical microscopy, scanning electron microscope equipped with energy-dispersive X-ray spectrometer (SEM-EDX), X-ray diffraction (XRD), cold-vapor atomic absorption spectrometry (CV-AAS), atomic fluorescence spectrometry (AFS), inductively coupled-plasma mass spectrometry (ICP-MS), and ion-selective electrode (ISE). The results show that various minerals in coal contain variable amounts of trace elements. Clay minerals have high concentrations of Ba, Be, Cs, F, Ga, Nb, Rb, Th, U, and Zr. Quartz has little contribution to the concentration of trace elements in bulk coal. Arsenic, Mn, and Sr are in high concentrations in calcite. Pyrite has high concentrations of As, Cd, Hg, Mo, Sb, Se, Tl, and Zn. Different genetic types of calcite in coal can accumulate different trace elements; for example Ba, Co, Cr, Hg, Ni, Rb, Sn, Sr, and Zn are in higher concentrations in calcite deposited from low-temperature hydrothermal fluid than in that deposited from ground water. Furthermore, the concentrations of some trace elements are quite variable in pyrite; different genetic types of pyrites (Py-A, B, C, D) have different concentrations of trace elements, and the concentrations of trace elements are also different in pyrite of low-temperature hydrothermal origin collected from different locations. The study shows that elemental concentration is rather uniform in a pyrite vein. There are many micron and submicron mosaic pyrites in a pyrite vein, which is enriched in some trace elements, such as As and Mo. The content of trace element in pyrite vein depends upon the content of mosaic pyrite and of trace elements in it. Many environmentally sensitive trace elements are mainly contained in the minerals in coal, and hence the physical coal cleaning techniques can remove minerals from coal and decrease the emissions of potentially hazardous trace elements. ?? 2002 Elsevier Science B.V. All rights reserved.

Trace- and rare-earth element geochemistry and Pb-Pb dating of black shales and intercalated Ni-Mo-PGE-Au sulfide ores in Lower Cambrian strata, Yangtze Platform, South China

NASA Astrophysics Data System (ADS)

Jiang, Shao-Yong; Chen, Yong-Quan; Ling, Hong-Fei; Yang, Jing-Hong; Feng, Hong-Zhen; Ni, Pei

2006-08-01

The Lower Cambrian black shale sequence of the Niutitang Formation in the Yangtze Platform, South China, hosts an extreme metal-enriched sulfide ore bed that shows >10,000 times enrichment in Mo, Ni, Se, Re, Os, As, Hg, and Sb and >1,000 times enrichment in Ag, Au, Pt, and Pd, when compared to average upper continental crust. We report in this paper trace- and rare-earth-element concentrations and Pb-Pb isotope dating for the Ni-Mo-PGE-Au sulfide ores and their host black shales. Both the sulfide ores and their host black shales show similar trace-element distribution patterns with pronounced depletion in Th, Nb, Hf, Zr, and Ti, and extreme enrichment in U, Ni, Mo, and V compared to average upper crust. The high-field-strength elements, such as Zr, Hf, Nb, Ta, Sc, Th, rare-earth elements, Rb, and Ga, show significant inter-element correlations and may have been derived mainly from terrigenous sources. The redox sensitive elements, such as V, Ni, Mo, U, and Mn; base metals, such as Cu, Zn, and Pb; and Sr and Ba may have been derived from mixing of seawater and venting hydrothermal sources. The chondrite-normalized REE patterns, positive Eu and Y anomalies, and high Y/Ho ratios for the Ni-Mo-PGE-Au sulfide ores are also suggestive for their submarine hydrothermal-exhalative origin. A stepwise acid-leaching Pb-Pb isotope analytical technique has been employed for the Niutitang black shales and the Ni-Mo-PGE-Au sulfide ores, and two Pb-Pb isochron ages have been obtained for the black shales (531±24 Ma) and for the Ni-Mo-PGE-Au sulfide ores (521±54 Ma), respectively, which are identical and overlap within uncertainty, and are in good agreement with previously obtained ages for presumed age-equivalent strata.

Effects of alloying elements and heat treatments on mechanical properties of Korean reduced-activation ferritic-martensitic steel

NASA Astrophysics Data System (ADS)

Chun, Y. B.; Kang, S. H.; Noh, S.; Kim, T. K.; Lee, D. W.; Cho, S.; Jeong, Y. H.

2014-12-01

As part of an alloy development program for Korean reduced-activation ferritic-martensitic (RAFM) steel, a total of 37 program alloys were designed and their mechanical properties were evaluated with special attention being paid to the effects of alloying elements and heat treatments. A reduction of the normalizing temperature from 1050 °C to 980 °C was found to have a positive effect on the impact resistance, resulting in a decrease in ductile-brittle transition-temperature (DBTT) of the program alloys by an average of 30 °C. The yield strength and creep rupture time are affected strongly by the tempering time at 760 °C but at the expense of ductility. Regarding the effects of the alloying elements, the addition of trace amounts of Zr enhances both the creep and impact resistance: the lowest DBTT was observed for the alloys containing 0.005 wt.% Zr, whereas the addition of 0.01 wt.% Zr extends the creep rupture-time under an accelerated condition. The enhanced impact resistance owing to the normalizing at lower temperature is attributed to a more refined grain structure, which provides more barriers to the propagation of cleavage cracks. Solution softening by Zr addition is suggested as a possible mechanism for enhanced resistance to both impact and creep of the program alloys.

Direct identification of trace metals in fine and ultrafine particles in the Detroit urban atmosphere.

PubMed

Utsunomiya, Satoshi; Jensen, Keld A; Keeler, Gerald J; Ewing, Rodney C

2004-04-15

Exposure to airborne particulates containing low concentrations of heavy metals, such as Pb, As, and Se, may have serious health effects. However, little is known about the speciation and particle size of these airborne metals. Fine- and ultrafine particles with heavy metals in aerosol samples from the Detroit urban area, Michigan, were examined in detail to investigate metal concentrations and speciation. The characterization of individual particles was completed using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) combined with conventional high-resolution TEM techniques. The trace elements, Pb, As, La, Ce, Sr, Zn, Cr, Se, Sn, Y, Zr, Au, and Ag, were detected, and the elemental distributions were mapped in situ atthe nanoscale. The crystal structures of the particles containing Pb, Sr, Zn, and Au were determined from their electron diffraction patterns. Based on the characterization of the representative trace element particles, the potential health effects are discussed. Most of the trace element particles detected in this study were within a range of 0.01-1.0 microm in size, which has the longest atmospheric residence time (approximately 100 days). Increased chemical reactivity owing to the size of nanoparticles may be expected for most of the trace metal particles observed.

Apollo 16 returned lunar samples - Lithophile trace-element abundances

NASA Technical Reports Server (NTRS)

Philpotts, J. A.; Schuhmann, S.; Kouns, C. W.; Lum, R. K. L.; Bickel, A. L.; Schnetzler, C. C.

1973-01-01

Lithium, K, Rb, Sr, Ba, rare-earth, Zr, and Hf abundances have been determined by mass-spectrometric isotope-dilution for Apollo 16 soils, anorthosite 61016, and 'basalt' 68415 whole-rock and separated pyroxene and plagioclase. Our sample of 61016 is similar to some other lunar anorthosites in lithophile trace-element concentrations but at a slightly lower level. It was probably accumulated from a little differentiated basalt. Basalt 68415 might be a homogeneous mixture of KREEP and anorthosite material; it appears to have crystallized under conditions as reducing as those holding for mare-basalts. The soil fines cover only a limited compositional range. No obvious chemical differences were noted between the Descartes and Cayley formations. Most of the compositional variation of the soils can be accounted for in terms of the addition of plagioclase. The existence of very high alumina basalt as an independent magma-type appears debatable in view of its KREEP-like lithophile trace-element relative concentrations and the observed lunar radioactivity distribution.

Deep-sea fluxes of barium and lithogenic trace elements in the subtropical northeast Atlantic

NASA Astrophysics Data System (ADS)

Stern, Judith; Dellwig, Olaf; Waniek, Joanna J.

2017-04-01

Total particle flux, Barium and lithogenic trace element fluxes were measured at the mooring Kiel 276 (33°N, 22°W) in the deep-sea of the subtropical Northeast Atlantic. The particulate material was collected between 2002 and 2008 with a sediment trap in 2000 m depth and analyzed with ICP-OES/-MS to determine its geochemical composition. The particle flux is controlled by primary production, lithogenic particle inputs via atmospheric transport and the migration of the Azores Front. We used refractory trace elements (eg. Ti, Zr, and the rare earth elements) to demonstrate the changes in flux and composition of the material due to lithogenic inputs. Shortly after periods of high dust load and enhanced primary production an increase in lithogenic trace element fluxes occurred. Especially the formation of aggregates with biogenic matter seems to have a major impact on the downwards transport of lithogenic particles. The observation of particulate Ba is of great interest since it is known as a proxy for past and present primary production. Ba fluxes ranging between 0.02 mg m-2 d-1 and 1.21 mg m-2 d-1 with biogenic proportions up to 97%. The fluxes of particulate Barium in the water column are mainly attributed to the strength of primary production.

Trace element accumulation in hawksbill turtles (Eretmochelys imbricata) and green turtles (Chelonia mydas) from Yaeyama Islands, Japan.

PubMed

Anan, Y; Kunito, T; Watanabe, I; Sakai, H; Tanabe, S

2001-12-01

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Zr, Mo, Ag, Cd, Sb, Ba, Hg, Tl, and Pb) were determined in the liver, kidney, and muscle of green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) from Yaeyama Islands, Okinawa, Japan. Accumulation features of trace elements in the three tissues were similar between green and hawksbill turtles. No gender differences in trace element accumulation in liver and kidney were found for most of the elements. Significant growth-dependent variations were found in concentrations of some elements in tissues of green and hawksbill turtles. Significant negative correlations (p < 0.05) were found between standard carapace length (SCL) and the concentrations of Cu, Zn, and Se in the kidney and V in muscle of green turtles and Mn in the liver, Rb and Ag in kidney, and Hg in muscle of hawksbill turtles. Concentrations of Sr, Mo, Ag, Sb, and Tl in the liver, Sb in kidney, and Sb and Ba in muscle of green turtles and Se and Hg in the liver and Co, Se, and Hg in kidney of hawksbill turtles increased with an increase in SCL (p < 0.05). Green and hawksbill turtles accumulated extremely high concentrations of Cu in the liver and Cd in kidney, whereas the levels of Hg in liver were low in comparison with those of other higher-trophic-level marine animals. High accumulation of Ag in the liver of green turtles was also observed. To evaluate the trophic transfer of trace elements, concentrations of trace elements were determined in stomach contents of green and hawksbill turtles. A remarkably high trophic transfer coefficient was found for Ag and Cd in green turtles and for Cd and Hg in hawksbill turtles.

Trace elements in lake sediments measured by the PIXE technique

NASA Astrophysics Data System (ADS)

Gatti, Luciana V.; Mozeto, Antônio A.; Artaxo, Paulo

1999-04-01

Lakes are ecosystems where there is a great potential of metal accumulation in sediments due to their depositional characteristics. Total concentration of trace elements was measured on a 50 cm long sediment core from the Infernão Lake, that is an oxbow lake of the Moji-Guaçu River basin, in the state of São Paulo, Brazil. Dating of the core shows up to 180 yrs old sediment layers. The use of the PIXE technique for elemental analysis avoids the traditional acid digestion procedure common in other techniques. The multielemental characteristic of PIXE allows a simultaneous determination of about 20 elements in the sediment samples, such as, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Zr, Ba, and Pb. Average values for the elemental composition were found to be similar to the bulk crustal composition. The lake flooding pattern strongly influences the time series of the elemental profiles. Factor analysis of the elemental variability shows five factors. Two of the factors represent the mineralogical matrix, and others represent the organic component, a factor with lead, and another loaded with chromium. The mineralogical component consists of elements such as, Fe, Al, V, Ti, Mn, Ni, K, Zr, Sr, Cu and Zn. The variability of Si is explained by two distinct factors, because it is influenced by two different sources, aluminum-silicates and quartz, and the effect of inundation are different for each other. The organic matter is strongly associated with calcium, and also bounded with S, Zn, Cu and P. Lead and chromium appears as separated factors, although it is not clear the evidences for their anthropogenic origin. The techniques developed for sample preparation and PIXE analysis was proven as advantageous and provided very good reproducibility and accuracy.

Rutile solubility in NaF–NaCl–KCl-bearing aqueous fluids at 0.5–2.79GPa and 250–650°C

DOE PAGES

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; ...

2016-01-14

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nbmore » and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 degrees C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at similar to 300 degrees C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 degrees C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log D-Zr similar to 10(-25) m(2)/s at 650 degrees C and similar to 10(-30) m(2)/s at 250 degrees C) with diffusion length-scales of <0.2 mu m in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nbmore » and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 degrees C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at similar to 300 degrees C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 degrees C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log D-Zr similar to 10(-25) m(2)/s at 650 degrees C and similar to 10(-30) m(2)/s at 250 degrees C) with diffusion length-scales of <0.2 mu m in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility« less

Fine-scale traverses in cumulate rocks, Stillwater Complex: A lunar analogue study

NASA Technical Reports Server (NTRS)

Elthon, Donald

1988-01-01

The objective was to document finite-scale compositional variations in cumulate rocks from the Stillwater Complex in Montana and to interpret these data in the context of planetary magma fractionation processes such as those operative during the formation of the Earth's Moon. This research problem involved collecting samples in the Stillwater Complex and analyzing them by electron microprobe, X-ray fluorescence (XRF), and instrumental neutron activation analysis (INAA). The electron microprobe is used to determine the compositions of cumulus and intercumulus phases in the rocks, the XRF is used to determine the bulk-rock major element and trace element (Y, Sr, Rb, Zr, Ni, and Cr) abundances, and the INAA lab. is used to determine the trace element (Sc, Co, Cr, Ni, Ta, Hf, U, Th, and the REE) abundances of mineral separates and bulk rocks.

PIXE analysis of ancient Chinese Changsha porcelain

NASA Astrophysics Data System (ADS)

Lin, E. K.; Yu, Y. C.; Wang, C. W.; Liu, T. Y.; Wu, C. M.; Chen, K. M.; Lin, S. S.

1999-04-01

In this work, proton induced X-ray emission (PIXE) method was applied for the analysis of ancient Chinese Changsha porcelain produced in the Tang dynasty (AD 618-907). A collection of glazed potsherds was obtained in the complex of the famous kiln site at Tongguan, Changsha city, Hunan province. Studies of elemental composition were carried out on ten selected Changsha potsherds. Minor and trace elements such as Ti, Mn, Fe, Co, Cu, Rb, Sr, and Zr in the material of the porcelain glaze were determined. Variation of these elements from sample to sample was investigated. Details of results are presented and discussed.

Trace element diffusion and kinetic fractionation in wet rhyolitic melt

NASA Astrophysics Data System (ADS)

Holycross, Megan E.; Watson, E. Bruce

2018-07-01

Piston-cylinder experiments were run to determine the chemical diffusivities of 21 trace elements (Sc, V, Y, Zr, Nb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Hf, Th and U) in hydrous rhyolitic melts at 1 GPa pressure and temperatures from 850 to 1250 °C. Diffusion couple glasses were doped with trace elements in low concentrations to characterize the diffusivities of all cations in a single experiment. Laser ablation ICP-MS was used to evaluate the trace element concentration gradients that developed in the silicate glasses. All calculated diffusion coefficients correspond to the temperature dependence D = D0exp(-Ea/RT). Rhyolite liquids contained either ∼4.1 wt% or ∼6.2 wt% dissolved H2O; separate Arrhenius relationships are produced for each melt composition. Trace element diffusivities in the melt with 6.2 wt% H2O are roughly two times higher than those in the less hydrous melt. Calculated trace element diffusion coefficients cover nearly two orders of magnitude at a given temperature. The high field strength elements are the slowest diffusers, followed by the transition metals and heavy rare earth elements. The light rare earth elements have the fastest diffusion rates in hydrous rhyolitic melt. The measured diffusion coefficients range down to values sufficiently low to preclude diffusive homogenization over geochemically realistic time scales in some cases. The substantial differences in the diffusivities of individual cations may result in fractionated trace element signatures in rhyolite melt pockets. A simple model is used to explore the potential for kinetic fractionation of REE during growth of an apatite crystal in a diffusive boundary layer locally saturated in P2O5. The faster-diffusing light REE are more efficiently transported away from the crystal interface than the slower-moving heavy REE. Diffusion effects will enrich the melt boundary layer in slow-moving HREE relative to the faster LREE. The kinetic fractionation of REE in the melt growth medium will result in a precipitated apatite crystal with a disequilibrium trace element composition.

Refertilization process in the Patagonian subcontinental lithospheric mantle of Estancia Sol de Mayo (Argentina)

NASA Astrophysics Data System (ADS)

Melchiorre, Massimiliano; Coltorti, Massimo; Gregoire, Michel; Benoit, Mathieu

2015-05-01

Anhydrous mantle xenoliths equilibrated at 1003-1040 °C from Estancia Sol de Mayo (ESM, Central Patagonia, Argentina) and entrained in post-plateau alkaline lavas belonging to Meseta Lago Buenos Aires have been investigated aiming at reconstructing the depletion and enrichment processes that affected this portion of the Patagonia lithospheric mantle. Xenoliths are characterized by a coarse-grained protogranular texture and are devoid of evident modal metasomatism. They show two texturally different clinopyroxenes: protogranular (cpx1) and texturally related to spinel (cpx2). Three different types of orthopyroxenes are also recognized: large protogranular crystals with exsolution lamellae (opx1); small clean and undeformed grains without exsolution lamellae (opx2) and small grains arranged in a vein (opx3). Major element composition of clinopyroxenes and orthopyroxenes highlights two different trends characterized by i) a high Al2O3 content at almost constant mg# and ii) a slight increase in Al2O3 content with decreasing mg#. Clinopyroxenes are enriched in LREE and are characterized by prominent to slightly negative Nb, Zr and Ti anomalies. No geochemical differences are observed between cpx1 and cpx2, while a discrimination can be observed between opx1 and opx2 (LREE-depleted; prominent to slightly negative Ti and Zr anomalies) and opx3 (prominent positive Zr anomaly). Partial melting modeling using both major and trace elements indicates a melting degree between ~ 5% and ~ 13% (up to ~ 23% according to major element modeling) for lherzolites and between ~ 20% and ~ 30% for harzburgites (down to ~ 5% according to trace element modeling). La/Yb and Al2O3, as well as Sr and Al2O3 negative correlations in clinopyroxenes point to a refertilization event affecting this lithospheric mantle. The agent was most probably a transitional alkaline/subalkaline melt, as indicated by the presence of orthopyroxene in the vein and the similar geochemical features of ESM clinopyroxenes and those from Northern Patagonia pyroxenites which are derived from transitional alkaline/subalkaline lavas.

Trace and surface analysis of ceramic layers of solid oxide fuel cells by mass spectrometry.

PubMed

Becker, J S; Breuer, U; Westheide, J; Saprykin, A I; Holzbrecher, H; Nickel, H; Dietze, H J

1996-06-01

For the trace analysis of impurities in thick ceramic layers of a solid oxide fuel cell (SOFC) sensitive solid-state mass spectrometric methods, such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and radiofrequency glow discharge mass spectrometry (rf-GDMS) have been developed and used. In order to quantify the analytical results of LA-ICP-MS, the relative sensitivity coefficients of elements in a La(0.6)Sr(0.35)MnO(3) matrix have been determined using synthetic standards. Secondary ion mass spectrometry (SIMS) - as a surface analytical method - has been used to characterize the element distribution and diffusion profiles of matrix elements on the interface of a perovskite/Y-stabilized ZrO(2) layer. The application of different mass spectrometric methods for process control in the preparation of ceramic layers for the SOFC is described.

A Compilation of Metals and Trace Elements Extracted from Materials Relevant to Pharmaceutical Applications such as Packaging Systems and Devices.

PubMed

Jenke, Dennis; Rivera, Christine; Mortensen, Tammy; Amin, Parul; Chacko, Molly; Tran, Thang; Chum, James

2013-01-01

Nearly 100 individual test articles, representative of materials used in pharmaceutical applications such as packaging and devices, were extracted under exaggerated conditions and the levels of 32 metals and trace elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ge, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, V, Zn, and Zr) were measured in the extracts. The extracting solvents included aqueous mixtures at low and high pH and an organic solvent mixture (40/60 ethanol water). The sealed vessel extractions were performed by placing an appropriate portion of the test articles and an appropriate volume of extracting solution in inert extraction vessels and exposing the extraction units (and associated extraction blanks) to defined conditions of temperature and duration. The levels of extracted target elements were measured by inductively coupled plasma atomic emission spectroscopy. The overall reporting threshold for most of the targeted elements was 0.05 μg/mL, which corresponds to 0.5 μg/g for the most commonly utilized extraction stoichiometry (1 g of material per 10 mL of extracting solvent). The targeted elements could be classified into four major groups depending on the frequency with which they were present in the over 250 extractions reported in this study. Thirteen elements (Ag, As, Be, Cd, Co, Ge, Li, Mo, Ni, Sn, Ti, V, and Zr) were not extracted in reportable quantities from any of the test articles under any of the extraction conditions. Eight additional elements (Bi, Cr, Cu, Mn, Pb, Sb, Se, and Sr) were rarely extracted from the test articles at reportable levels, and three other elements (Ba, Fe, and P) were infrequently extracted from the test articles at reportable levels. The remaining eight elements (Al, B, Ca, Mg, Na, S, Si, and Zn) were more frequently present in the extracts in reportable quantities. These general trends in accumulation behavior were compared to compiled lists of elements of concern as impurities in pharmaceutical products. Nearly 100 individual test articles, representative of materials used in pharmaceutical applications such as packaging and devices, were extracted under exaggerated conditions, and the levels of thirty-two metals and trace elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ge, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, V, Zn, and Zr) were measured in the extracts. The targeted elements could be classified into four major groups depending on the frequency with which they were present in the extractions reported in this study: those elements that were not extracted in reportable quantities from any of the test articles under any of the extraction conditions, those elements that were rarely extracted from the test articles at reportable levels, those elements that were infrequently extracted from the test articles at reportable levels, and those elements that were more frequently present in the extracts in reportable quantities.

Petrogenesis of Pliocene Alkaline Volcanic Rocks from Southeastern Styrian Basin, Austria

NASA Astrophysics Data System (ADS)

Ali, Sh.; Ntaflos, Th.

2009-04-01

Petrogenesis of Pliocene Alkaline Volcanic Rocks from Southeastern Styrian Basin, Austria Sh. Ali and Th. Ntaflos Dept. of Lithospheric Research, University of Vienna, Austria Neogene volcanism in the Alpine Pannonian Transition Zone occurred in a complex geodynamic setting. It can be subdivided into a syn-extentional phase that comprises Middle Miocene dominantly potassic, intermediate to acidic volcanism and a post-extensional phase, which is characterized by eruption of alkaline basaltic magmas during the Pliocene to Quartenary in the Styrian Basin. These alkaline basaltic magmas occur as small eruptive centers dominating the geomorphology of the southeastern part of the Styrian Basin. The eruptive centers along the SE Styrian Basin from North to South are: Oberpullendorf, Pauliberg, Steinberg, Strandenerkogel, Waltrafelsen and Klöch. The suite collected volcanic rocks comprise alkali basalts, basanites and nephelinites. Pauliberg: consists of alkali basalts that exhibit a narrow range of SiO2 (44.66-47.70 wt %) and wide range of MgO (8.52-13.19-wt %), are enriched in TiO2 (3.74-4.18 wt %). They are enriched in incompatible trace elements such as Zr (317-483 ppm), Nb (72.4-138 ppm) and Y (30.7-42 ppm). They have Nb/La ratio of 1.89 (average) and Cen/Ybn=15.22-23.11. Oberpullendorf: it also consists of alkali basalts with higher SiO2 (50.39 wt %) and lower TiO2 (2.80 wt %) if compared with the Pauliberg suite. Incompatible trace elements are lower than in Pauliberg; Zr =217 ppm, Nb=49.8 ppm, Y=23.6 ppm and Nb/La=1.93. The Oberpullendorf alkalibasalts are relative to Pauliberg lavas more depleted in LREE (Cen/Ybn=12.78). Steinberg: it consists of basanites with SiO2=44.49-46.85 wt %, MgO=6.30-9.13-wt %, and TiO2 =2.09-2.26 wt %. They are enriched in incompatible trace elements such as Zr (250-333 ppm), Nb (94-130 ppm), Y (24.7-31.9 ppm) and Nb/La=1.59 (average). The Cen/Ybn ratio varies between 18.17 and 22.83 indicating relative steep REE chondrite normalized patterns. Strandenerkogel: it consists of nephelinites with narrow compositional ranges; SiO2 =40.99-42.44 wt %, MgO=6.63-6.92 wt % and TiO2=2.03-2.07 wt %. They are enriched in incompatible trace elements such as Zr (362-382 ppm), Nb (139-153 ppm) and Y (39.5-40.7 ppm). They have Nb/La ratio of 1.20 and are strongly enriched in LREE (Cen/Ybn=25.04-28.11). Waltrafelsen: there are like in Strandenerkogel and have SiO2=42.42 wt %, MgO=6.55 wt %, and TiO2=2.01 wt %. The incompatible trace elements such as Zr (362 ppm), Nb (145 ppm) and Y (38.3 ppm) are similar to that of Stranerkogel. They have Nb/La ratio of 1.27 and are strongly enriched in LREE (Cen/Ybn=24.92). Klöch: it consists of basanites with similar to Steinberg composition (SiO2=45.34-46.60 wt %, MgO=8.98-10.11 wt %, and TiO2= 2.28-2.37 wt %. Incompatible trace elements such as Zr (252-273 ppm), Nb (94.2-101 ppm) and Y (24.4-27.2 ppm) are high. They have Nb/La ratio of 1.71 (average). Their REE abundances compared to Steinberg are slightly lower (Cen/Ybn=18.19-20.17). The Nb/La ratio of all the studied rock varieties is greater than one indicates an OIB-like asthenospheric mantle source for the basaltic magma. All the studied rock varieties except alkali basalts of Pauliberg have Tbn/Ybn ratios which are comparable to those of the alkali basalts of Hawaii ((Tbn/Ybn range from 1.89 to 2.45); the Hawaiian basalts are considered to have been derived from a garnet-lherzolite mantle source (Frey et al. 1991; McKenzie & O'Nions, 1991). The chondrite normalized HREE abundances indicate the presence of garnet as a residual phase in the melt source region as can be inferred from the Dy/Yb ratio (average 2.93) which is greater than that of chondritic Dy/Yb ratio (1.57) All the studied rock varieties display alkaline affinity and negative K-anomaly. The negative K-anomaly suggests either a source character, (e.g. frozen HIMU-like veins or pockets in the depleted lherzolite)? or it is consistent with the presence of a K-bearing hydrous phase in the residual mantle. References FREY, F. A., GARCIA, M. O., WISE, W. S., KENNEDY, A., GURRIET, P. & ALBAREDE, F. 1991. The evolution of Mauna Kea volcano, Hawaii: Petrogenesis of tholeiitic and alkali basalts. Journal of Geophysical Research 96, 14347-75. MCKENZIE, D. P. & O'NIONS, R. K. 1991. Partial melting distributions from inversion of rare earth element concentrations. Journal of Petrology 32, 1021-91.

Petrology and trace element geochemistry of the Honolulu volcanics, Oahu: implications for the oceanic mantle below Hawaii.

USGS Publications Warehouse

Clague, D.A.; Frey, F.A.

1982-01-01

These volcanic rocks are the products of small-volume, late-stage vents along rifts cutting the older massive Koolan tholeiitic shield on Oahu. Most of the lavas and tuffs have the geochemical features expected of near-primary magmas derived from a peridotite source with olivine Fo87-89, e.g. 100 Mg/(Mg + Fe2+) > 65, Ni > 250 p.p.m. and the presence of ultramafic mantle xenoliths at 18 of the 37 vents. Thus the geochemistry of the alkali olivine basalt, basanite, nephelinite and nepheline melilitite lavas and tuffs of these Honolulu volcanic rocks has been used to deduce the composition of their mantle source and the conditions under which they were generated by partial melting in the mantle. New major- and trace-element analyses for 31 samples are tabulated and indicate derivation by partial melting of a garnet (<10%) lherzolite source which was isotopically homogeneous and compositionally uniform for most major and trace elements, though apparently heterogeneous in TiO2, Zr, Hf, Nb and Ta (due perhaps to the low inferred degrees of melting which failed to exhaust the source in minor residual phases). In comparison with estimates of a primordial mantle composition and the mantle source of MORB, the garnet peridotite source of these Honolulu volcanics was increasingly enriched in the sequence heavy REE, Y, Tb, Ti, Sm, Zr and Hf, for which a multi-stage history is required. This composition differs from the source of the previously erupted tholeiitic shield, nor is it represented in the upper-mantle xenoliths in the lavas and tuff of the unit.-R.A.H.

Simultaneous spectrophotometric determination of trace amounts of uranium, thorium, and zirconium using the partial least squares method after their preconcentration by alpha-benzoin oxime modified Amberlite XAD-2000 resin.

PubMed

Ghasemi, Jahan B; Zolfonoun, E

2010-01-15

A new solid phase extraction method for separation and preconcentration of trace amounts of uranium, thorium, and zirconium in water samples is proposed. The procedure is based on the adsorption of U(VI), Th(IV) and Zr(IV) ions on a column of Amberlite XAD-2000 resin loaded with alpha-benzoin oxime prior to their simultaneous spectrophotometric determination with Arsenazo III using orthogonal signal correction partial least squares method. The enrichment factor for preconcentration of uranium, thorium, and zirconium was found to be 100. The detection limits for U(VI), Th(IV) and Zr(IV) were 0.50, 0.54, and 0.48microgL(-1), respectively. The precision of the method, evaluated as the relative standard deviation obtained by analyzing a series of 10 replicates, was below 4% for all elements. The practical applicability of the developed sorbent was examined using synthetic seawater, natural waters and ceramic samples.

Trace elements in magnetite as petrogenetic indicators

NASA Astrophysics Data System (ADS)

Dare, Sarah A. S.; Barnes, Sarah-Jane; Beaudoin, Georges; Méric, Julien; Boutroy, Emilie; Potvin-Doucet, Christophe

2014-10-01

We have characterized the distribution of 25 trace elements in magnetite (Mg, Al, Si, P, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Sn, Hf, Ta, W, and Pb), using laser ablation ICP-MS and electron microprobe, from a variety of magmatic and hydrothermal ore-forming environments and compared them with data from the literature. We propose a new multielement diagram, normalized to bulk continental crust, designed to emphasize the partitioning behavior of trace elements between magnetite, the melt/fluid, and co-crystallizing phases. The normalized pattern of magnetite reflects the composition of the melt/fluid, which in both magmatic and hydrothermal systems varies with temperature. Thus, it is possible to distinguish magnetite formed at different degrees of crystal fractionation in both silicate and sulfide melts. The crystallization of ilmenite or sulfide before magnetite is recorded as a marked depletion in Ti or Cu, respectively. The chemical signature of hydrothermal magnetite is distinct being depleted in elements that are relatively immobile during alteration and commonly enriched in elements that are highly incompatible into magnetite (e.g., Si and Ca). Magnetite formed from low-temperature fluids has the lowest overall abundance of trace elements due to their lower solubility. Chemical zonation of magnetite is rare but occurs in some hydrothermal deposits where laser mapping reveals oscillatory zoning, which records the changing conditions and composition of the fluid during magnetite growth. This new way of plotting all 25 trace elements on 1 diagram, normalized to bulk continental crust and elements in order of compatibility into magnetite, provides a tool to help understand the processes that control partitioning of a full suit of trace elements in magnetite and aid discrimination of magnetite formed in different environments. It has applications in both petrogenetic and provenance studies, such as in the exploration of ore deposits and in sedimentology.

Geochemistry and petrogenesis of a peralkaline granite complex from the Midian Mountains, Saudi Arabia

NASA Astrophysics Data System (ADS)

Harris, N. B. W.; Marriner, G. F.

1980-10-01

A zoned intrusion with a biotite granodiorite core and arfvedsonite granite rim represents the source magma for an albitised granite plug near its eastern margin and radioactive siliceous veins along its western margin. A study of selected REE and trace elements of samples from this complex reveals that the albitised granite plug has at least a tenfold enrichment in Zr, Hf, Nb, Ta, Y, Th, U and Sr, and a greatly enhanced heavy/light REE ratio compared with the peralkaline granite. The siliceous veins have even stronger enrichment of these trace elements, but a heavy/light REE ratio and negative eu anomaly similar to the peralkaline granite. It is suggested that the veins were formed from acidic volatile activity and the plug from a combination of highly fractionated magma and co-existing alkaline volatile phase. The granodiorite core intrudes the peralkaline granite and has similar trace element geochemistry. The peralkaline granite is probably derived from the partial melting of the lower crust in the presence of halide-rich volatiles, and the granodiorite from further partial melting under volatile-free conditions.

U-Pb zircon geochronology and Zr-in-rutile thermometry of eclogites from the Dulan area, North Qaidam ultra-high pressure (UHP) terrane, western China

NASA Astrophysics Data System (ADS)

Hernández Uribe, D.; Stubbs, K.; Lehman, M. R.; Gilmore, V.; Kylander-Clark, A. R.; Mattinson, C. G.

2016-12-01

The Dulan area, in the North Qaidam terrane, exposes UHP eclogites and gneisses that experienced a 20 Myr UHP event at P-T conditions of 30 kbar and 700 °C. Two eclogites were analyzed using Zr-in-rutile thermometry and zircon U-Pb + trace element analysis to constrain the metamorphic evolution of the area. A kyanite-phengite eclogite presents a mineral assemblage of grt + omp + ph + ky + rt + zo + qz. Rutile analyses show a Zr concentration of 173-250 ppm with a mean of 207 ± 19 ppm. The calculated temperatures yielded 685-716 °C with an average of 700 ± 7°C. Zircon U-Pb analyses gave an upper intercept age of 880 ± 89 Ma. These analyses from cathodoluminiscence (CL)-dark core zircons show a negative Eu anomaly and a steep HREE slope suggesting a magmatic origin for the protolith. Analyses from CL-bright rims gave a weighted mean age of 427 ± 2 Ma. These zircons show an eclogite facies trace elements pattern suggesting that the age represent the HP-UHP event. Titanium concentration in zircons gave a weighted mean of 4.41 ± 0.25 ppm. This Ti concentration yielded a calculated temperature of 674 °C A phengite eclogite shows a mineral assemblage of grt + omp + ph + rt + zo + qz. Rutile in matrix analyses show a Zr concentration of 123-161 ppm with a mean of 139 ± 9 ppm. Calculated temperatures for these rutiles ranges from 659-680 °C with a mean temperature of 668 ± 5 °C. U-Pb analyses from CL-dark zircon cores gave a weighted mean age of 844 ± 7 Ma. These zircons show a negative Eu anomaly and a steep HREE slope suggesting a magmatic origin for the protolith. Analyses from CL-grey rims gave a weighted mean age of 433 ± 4 Ma. These zircons show an eclogite facies trace elements pattern, representing the timing of the HP-UHP event. Titanium concentration in zircons gave a weighted mean of 3.13 ± 0.34 ppm. This concentration yielded calculated temperature 647 °C. The obtained ages are in the same range as the ones obtained for the northern and southern Dulan area suggesting that all the area belongs to the same tectonic unit and experienced the same continental collision metamorphism.

Rutile solubility in NaF-NaCl-KCl-bearing aqueous fluids at 0.5-2.79 GPa and 250-650 °C

NASA Astrophysics Data System (ADS)

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; Chow, Paul; Xiao, Yuming; Hanchar, John M.; Tschauner, Oliver; Shen, Guoyin

2016-03-01

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nb and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 °C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at ∼300 °C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 °C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log DZr ∼10-25 m2/s at 650 °C and ∼10-30 m2/s at 250 °C) with diffusion length-scales of <0.2 μm in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility.

Contribution of slab melting to magmatism at the active rifts zone in the middle of the Izu-Bonin arc

NASA Astrophysics Data System (ADS)

Hirai, Y.; Okamura, S.; Sakamoto, I.; Shinjo, R.; Wada, K.; Yoshida, T.

2016-12-01

The active rifts zone lies just behind the Quaternary volcanic front in the middle of the Izu-Bonin arc. Volcanism at the active rifts zone has been active since ca. 2 Ma, and late Quaternary basaltic lavas (< 0.1 Ma) and hydrothermal activity occur along the central axis of the rifts (Taylor, 1992; Ishizuka et al., 2003). In this paper we present new Sr, Nd, and Hf isotope and trace element data for the basalts erupted in the active rifts zone, including the Aogashima, Myojin and Sumisu rifts. Two geochemical groups can be identified within the active rift basalts: High-Zr basalts (HZB) and Low-Zr basalts (LZB). In the case of the Sumisu rift, the HZB exhibits higher in K2O, Na2O, Y, Zr and Ni, and also has higher Ce/Yb and Zr/Y, lower Ba/Th than the LZB. Depletion of Zr-Hf in the N-MORB spidergram characterizes the LZB from the Aogashima, Myojin and Sumisu rifts. The 176Hf/177Hf ratios are slightly lower in the HZB than in the LZB, decoupling of 176Hf/177Hf ratios and 143Nd/144Nd ratios. Estimated primary magma compositions suggest that primary magma segregation for the HZB occurred at depths less than 70 km ( 2 GPa), whereas the LZB more than 70 km (2 3 GPa). ODP Leg126 site 788, 790, and 791 reached the basaltic basement of the Sumisu rift (Gill et al., 1992). The geochemical data and stratigraphic relations of the basement indicate that the HZB is younger than the LZB. Geochemical modelling demonstrates that slab-derived melt mixed with mantle wedge produces the observed isotopic and trace elemental characteristics. The LZB volcanism at the early stage of the back-arc rifting is best explained by a partial melting of subducted slab saturated with trace quantities of zircon under low-temperature conditions in the mantle wedge. On the other hand, the HZB requires a partial melt of subducted slab accompanied by full dissolution of zircon under high-temperature conditions in the mantle wedge, which could have been caused by hot asthenospheric injection during the syn stage of the back-arc rifting. referencesGill et al. (1992) Proc. ODP, Sci. Result, 126, 383-403. Ishizuka et al. (2003) Geol. Soc. Spec. Publ., 219, 187-205. Taylor (1992) Proc. ODP, Sci. Result, 126, 627-651.

Mineralogical and geochemical characterization of weathering profiles developed on mylonites in the Fodjomekwet-Fotouni section of the Cameroon Shear Zone (CSZ), West Cameroon

NASA Astrophysics Data System (ADS)

Tematio, P.; Tchaptchet, W. T.; Nguetnkam, J. P.; Mbog, M. B.; Yongue Fouateu, R.

2017-07-01

The mineralogical and geochemical investigation of mylonitic weathering profiles in Fodjomekwet-Fotouni was done to better trace the occurrence of minerals and chemical elements in this area. Four representative soil profiles were identified in two geomorphological units (upland and lowland) differentiating three weathering products (organo-mineral, mineral and weathered materials). Weathering of these mylonites led to some minerals association such as vermiculite, kaolinite, goethite, smectite, halloysite, phlogopite and gibbsite. The minerals in a decreasing order of abundance are: quartz (24.2%-54.8%); kaolinite (8.4%-36.0%); phlogopite (5.5%-21.9%); goethite (7.8%-16.1%); vermiculite (6.7%-15.7%); smectite (10.2%-11.9%); gibbsite (9.0%-11.8%) and halloysite (5.6%-11.5%) respectively. Patterns of chemical elements allow highlighting three behaviors (enriched elements, depleted elements and elements with complex behavior), depending on the landscape position of the profiles. In the upland weathering products, K, Cr and REEs are enriched; Ca, Mg, Na, Mn, Rb, S and Sr are depleted while Si, Al, Fe, Ti, Ba, Co, Cu, Ga, Mo, Nb, Ni, Pb, Sc, V, Y, Zn and Zr portray a complex behavior. Contrarily, the lowland weathering profiles enriched elements are Fe, Ti, Co, Cr, Cu, V, Zr, Pr, Sm, Tb, Dy, Er and Yb; while depleted elements are Ca, Mg, K, Na, Mn, Ba, Ga, S, Sr, Y, Zn, La, Ce and Nd; and Si, Al, Mo, Nb, Ni, Pb, Rb, Sc evidenced complex behaviors. In all the studied weathering products, the REEs fractionation was also noticeable with a landscape-position dependency, showing light REEs (LREEs) enrichment in the upland areas and heavy REEs (HREEs) in lowland areas. SiO2, Al2O3 and Fe2O3 are positively correlated with most of the traces and REEs (Co, Cu, Nb, Ni, Mo, Pb, Sc, V, Zn, Zr, La, Ce, Sm, Tb, Dy, Er, Yb), pointing to the fact that they may be incorporated into newly formed clay minerals and oxides. Ba, Cr, Ga, Rb, S, Sr, Y, Pr and Nd behave like alkalis and alkaline earths, and are thus highly mobile during weathering.

Geochemistry of the Bonin Fore-arc Volcanic Sequence: Results from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Godard, M.; Ryan, J. G.; Shervais, J. W.; Whattam, S. A.; Sakuyama, T.; Kirchenbaur, M.; Li, H.; Nelson, W. R.; Prytulak, J.; Pearce, J. A.; Reagan, M. K.

2015-12-01

The Izu-Bonin-Mariana intraoceanic arc system, in the western Pacific, results from ~52 My of subduction of the Pacific plate beneath the eastern margin of the Philippine Sea plate. Four sites were drilled south of the Bonin Islands during IODP Expedition 352 and 1.22 km of igneous basement was cored upslope to the west of the trough. These stratigraphically controlled igneous suites allow study of the earliest stages of arc development from seafloor spreading to convergence. We present the preliminary results of a detailed major and trace element (ICPMS) study on 128 igneous rocks drilled during Expedition 352. Mainly basalts and basaltic andesites were recovered at the two deeper water sites (U1440 and U1441) and boninites at the two westernmost sites (U1439 and U1442). Sites U1440 and U1441 basaltic suites are trace element depleted (e.g. Yb 4-6 x PM); they have fractionated REE patterns (LREE/HREE = 0.2-0.4 x C1-chondrites) compared to mid-ocean ridge basalts. They have compositions overlapping that of previously sampled Fore-Arc Basalts (FAB) series. They are characterized also by an increase in LILE contents relative to neighboring elements up-section (e.g. Rb/La ranging from <1 to 3-7 x PM at Site U1440) suggesting a progressive contamination of their source by fluids. This process in turn may have favored melting and efficient melt extraction from the source and thus its extreme depletion. Boninites are depleted in moderately incompatible elements with a decrease in their contents up-section (e.g. Yb = ~6.2 to 2.8 x C1-chondrite at Site U1439). These changes in trace element contents are associated with the development of a positive Zr-Hf anomaly relative to neighboring elements and a strong increase in LILE (e.g., Zr/Sm=~1 to 2.6 x PM and Rb/La=1-2 to 10-18). The progressive upward depletion of boninitic lavas could reveal the incorporation of harzburgitic residues from FAB generation into their mantle source.

Increasing the Efficiency of Electron Microprobe Measurements of Minor and Trace Elements in Rutile

NASA Astrophysics Data System (ADS)

Neill, O. K.; Mattinson, C. G.; Donovan, J.; Hernández Uribe, D.; Sains, A.

2016-12-01

Minor and trace element contents of rutile, an accessory mineral found in numerous lithologic settings, has many applications for interpreting earth systems. While these applications vary widely, they share a need for precise and accurate elemental measurements. The electron microprobe can be used to measure rutile compositions, although long X-ray counting times are necessary to achieve acceptable precision. Continuum ("background") intensity can be estimated using the iterative Mean Atomic Number (MAN) method of Donovan and Tingle (1996), obviating the need for direct off-peak background measurements, and reducing counting times by half. For this study, several natural and synthetic rutiles were measured by electron microprobe. Data was collected once but reduced twice, using off-peak and an MAN background corrections, allowing direct comparison of the two methods without influence of other variables (counting time, analyte homogeneity, beam current, calibration standards, etc.). These measurements show that, if a "blank" correction (Donovan et al., 2011, 2016) is used, minor and trace elements of interest can be measured in rutile using the MAN background method in half the time of traditional off-peak measurements, without sacrificing accuracy or precision (Figure 1). This method has already been applied to Zr-in-rutile thermometry of ultra-high pressure metamorphic rocks from the North Qaidam terrane in northwest China. Finally, secondary fluorescence of adjacent phases by continuum X-rays can lead to artificially elevated concentrations. For example, when measuring Zr, care should be taken to avoid analytical spots within 100 microns of zircon or baddeleyite crystals. References: 1) J.J. Donovan and T.N Tingle (1996) J. Microscopy, 2(1), 1-7 2) J.J. Donovan, H.A. Lowers, and B.G. Rusk (2011) Am. Mineral., 96, 274­282 3) J.J. Donovan, J.W. Singer and J.T. Armstrong (2016) Am. Mineral., 101, 1839-1853 4) G.L. Lovizotto et al. (2009) Chem. Geol., 261, 346-369

The influence of melt composition on the partitioning of REEs, Y, Sc, Zr and Al between forsterite and melt in the system CMAS

NASA Astrophysics Data System (ADS)

Evans, Thomas M.; O'Neill, Hugh St. C.; Tuff, James

2008-12-01

Partition coefficients for a range of Rare Earth Elements (REEs), Y, Sc, Al and Zr were determined between forsteritic olivine (nearly end-member Mg 2SiO 4) and ten melt compositions in the system CaO-MgO-Al 2O 3-SiO 2 (CMAS) at 1 bar and 1400 °C, with concentrations of the trace elements in the olivine and the melt measured by laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The REEs and Sc were added at levels sufficient to ensure that concentrations in the olivine were well above the detection limits. The REE partition coefficients (DREEol/melt) decrease with increasing silica in the melt, indicating strong bonding between REEO 1.5 and SiO 2 in the melt. The variation of DREEol/melt as a function of ionic radius is well described by the Brice equation for each composition, although a small proportion of this variation is due to the increase in the strength of the REEO 1.5-SiO 2 interactions in the melt with ionic radius. Scandium behaves very similarly to the REEs, but a global fit of the data from all ten melt compositions suggests that DScol/melt deviates somewhat from the parabolas established by the REE and Y, implying that Sc may substitute into olivine differently to that of the REEs. In contrast to the behaviour of the large trivalent cations, the concentration of Al in olivine is proportional to the square root of its concentration in the melt, indicating a coupled substitution in olivine with a high degree of short-range order. The lack of any correlation of REE partition coefficients with Al in olivine or melt suggests that the REE substitution in olivine is charge-balanced by cation vacancies. The partition coefficient of the tetravalent trace element Zr, which is highly incompatible in olivine, depends on the CaO content of the melt.

In Situ Trace Element Measurements on Roda and the Origin of Diogenites

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Herrin, J. S.

2011-01-01

The origin of diogenites remains poorly understood. A recent model interprets many diogenites to have been formed from melts that were derived by remelting initial magma ocean cumulates, and these penultimate parent melts were then contaminated by melts derived from remelting of the basaltic (eucritic) crust to form the ultimate diogenite parent melts [1] (hereafter the remelting model). This is a very complicated petrogenesis that has profound implications for the geological evolution of 4 Vesta if correct. This model was developed based on trace element analyses of bulk rock samples that had been leached in acids to remove phosphates; the compositions of the residues were interpreted to be close to those of cumulus orthopyroxenes plagioclase, chromite and olivine [1]. In situ measurements of phases in diogenites can be used to test this model. We have begun a campaign of laser ablation ICP-MS of orthopyroxene grains in diogenites for this purpose. Here we report our first results on one diogenite, Roda. We have determined a suite of trace lithophile elements on nine, mm-sized pyroxene grains separated from Roda that have previously been studied [2, 3]. A key observation supporting the remelting model is the very low Eu/Eu* of leached residues; values too low to represent orthopyroxene that crystallized from melts with chondritic Sm/Eu and Gd/Eu [1]. (Eu* = Eu interpolated from REE diagrams.) Crustal remelts have low Sm/Eu and Gd/Eu, and orthopyroxenes that crystallized from parent melts contaminated by them would have very low Eu/Eu* [1]. Roda grains have Eu/Eu* of 0.243 to 0.026; the latter a value lower than any measured on bulk diogenite leached residues (0.041) [1]. There is a general negative correlation between Eu/Eu* and some incompatible elements (Zr, Nb, Hf), but not others (LREE). This appears inconsistent with the remelting model as it would suggest an evolving parent melt with La de-creasing as Zr increased and Eu/Eu* decreased. Grain R-15 includes trace-element-rich trapped melt phases [2, 3]. This grain has the highest Eu/Eu* and LREE contents, indicating that the trapped melt had a high Eu/Eu*. Thus, our first data on one diogenite do not provide support for the remelting model [1]. Roda is unusual in that its orthopyroxene grains show wide ranges in trace element contents [4]. Previous in situ REE analyses of grain R-15 did not reveal evidence for subsolidus equilibration with trace-element-rich trapped melt phases, and led to the suggestion that Roda may be polymict, with different grains representing different lithologies of diverse compositions [3]. Thus, based on our results on Roda, it is perhaps premature to abandon the remelting model. In situ measurements on a suite of diogenites is planned to further address this issue.

Geochemical landscapes of the conterminous United States; new map presentations for 22 elements

USGS Publications Warehouse

Gustavsson, N.; Bolviken, B.; Smith, D.B.; Severson, R.C.

2001-01-01

Geochemical maps of the conterminous United States have been prepared for seven major elements (Al, Ca, Fe, K, Mg, Na, and Ti) and 15 trace elements (As, Ba, Cr, Cu, Hg, Li, Mn, Ni, Pb, Se, Sr, V, Y, Zn, and Zr). The maps are based on an ultra low-density geochemical survey consisting of 1,323 samples of soils and other surficial materials collected from approximately 1960-1975. The data were published by Boerngen and Shacklette (1981) and black-and-white point-symbol geochemical maps were published by Shacklette and Boerngen (1984). The data have been reprocessed using weighted-median and Bootstrap procedures for interpolation and smoothing.

Biomonitoring of 37 trace elements in blood samples from inhabitants of northern Germany by ICP-MS.

PubMed

Heitland, Peter; Köster, Helmut D

2006-01-01

The trace elements Ag, As, Au, B, Ba, Be, Bi, Cd, Ce, Co, Cs, Cu, Ga, Hf, Hg, In, La, Mn, Mo, Ni, Pb, Pd, Rb, Rh, Ru, Sb, Se, Sn, Sr, Te, Th, Tl, U, V, W, Y and Zr were determined in 130 human blood samples from occupationally non-exposed volunteers living in the greater area of Bremen in northern Germany. The blood samples were collected in lithium heparin monovettes developed for trace metal determination and were analysed by inductively coupled plasma mass spectrometry (ICP-MS) with an octopole-based collision/reaction cell. For sample introduction into the ICP, the blood samples were diluted 1/10 (V/V) with a 0.1% Triton-X-100 and 0.5% (V/V) ammonia solution. The method validation of our developed routine method is described for all 37 elements and results about internal and external quality assurance are discussed. Information on exposure conditions of all human subjects were collected by questionnaire-based interviews, including smoking habits, seafood consumption and the type of dental alloys in the teeth. Mean values, geometric mean values, ranges and selected percentiles of all elemental concentrations in human blood are presented, which helps toxicologists and clinical chemists planning research about exposition to metals and health effects caused by exposition to metals.

Geochemical insights into the lithology of mantle sources for Cenozoic alkali basalts in West Qinling, China

NASA Astrophysics Data System (ADS)

Dai, Li-Qun; Zheng, Fei; Zhao, Zi-Fu; Zheng, Yong-Fei

2018-03-01

Although alkali basalts are common in oceanic islands and continental rifts, the lithology of their mantle sources is still controversial. While the peridotite is usually viewed as a common source lithology, there are increasing studies suggesting significant contributions from ultramafic metasomatites such as carbonated peridotite, pyroxenite and hornblendite to the origin of alkali basalts. The present study indicates that carbonated peridotite plus hornblendite would have served as the mantle sources of Cenozoic alkali basalts from the West Qinling orogen in China. The target basalts show low SiO2 contents of 36.9 to 40.8 wt% and highly variable Na2O + K2O contents from 0.86 to 4.77 wt%, but high CaO contents of 12.5 to 16.3 wt% and CaO/Al2O3 ratios of 1.42 to 2.19. They are highly enriched in the majority of incompatible trace elements, but depleted in Rb, K, Pb, Zr, Hf, and Ti. Furthermore, they exhibit high (La/Yb)N, Zr/Hf, Ce/Pb and Nb/Ta ratios, but low Ti/Eu and Hf/Sm ratios. Generally, with increasing (La/Yb)N and CaO/Al2O3 ratios, their Ti/Eu and Hf/Sm ratios decrease whereas their Zr/Hf, Ce/Pb and Nb/Ta ratios increase. These major and trace element features are similar to those of carbonatites and hornblendite-derived melts to some extent, but significantly different from those of mid-ocean ridge basalts (MORB). This suggests that the alkali basalts would be originated from metasomatic mantle sources. A comparison of the major-trace elements in the alkali basalts with those of some representative mantle-derived melts indicates that the source lithology of alkali basalts is a kind of ultramafic metasomatites that are composed of carbonated peridotite and hornblendite. Such metasomatites would be generated by reaction of the depleted MORB mantle peridotite with hydrous, carbonate-bearing felsic melts derived from partial melting of the subducted Paleotethyan oceanic crust. Therefore, the melt-peridotite reaction at the slab-mantle interface in the Paleotethyan subduction channel plays the key role in transferring the geochemical signatures from the subducted Paleotethyan oceanic crust to the alkali basalts in the fossil convergent plate margin.

The effect of melt composition on the partitioning of trace elements between titanite and silicate melt

NASA Astrophysics Data System (ADS)

Prowatke, S.; Klemme, S.

2003-04-01

The aim of this study is to systematically investigate the influence of melt composition on the partitioning of trace elements between titanite and different silicate melts. Titanite was chosen because of its important role as an accessory mineral, particularly with regard to intermediate to silicic alkaline and calc-alkaline magmas [e.g. 1] and of its relative constant mineral composition over a wide range of bulk compositions. Experiments at atmospheric pressure were performed at temperatures between 1150°C and 1050°C. Bulk compositions were chosen to represent a basaltic andesite (SH3 - 53% SiO2), a dacite (SH2 - 65 SiO2) and a rhyolite (SH1 - 71% SiO2). Furthermore, two additional experimental series were conducted to investigate the effect of Al-Na and the Na-K ratio of melts on partitioning. Starting materials consisted of glasses that were doped with 23 trace elements including some selected rare earth elements (La, Ce, Pr, Sm, Gd, Lu), high field strength elements (Zr, Hf, Nb, Ta) and large ion lithophile elements (Cs, Rb, Ba) and Th and U. The experimental run products were analysed for trace elements using secondary ion mass spectrometry at Heidelberg University. Preliminary results indicate a strong effect of melt composition on trace element partition coefficients. Partition coefficients for rare-earth elements uniformly show a convex-upward shape [2, 3], since titanite accommodates the middle rare-earth elements more readily than the light rare-earth elements or the heavy rare-earth elements. Partition coefficients for the rare-earth elements follow a parabolic trend when plotted against ionic radius. The shape of the parabola is very similar for all studied bulk compositions, the position of the parabola, however, is strongly dependent on bulk composition. For example, isothermal rare-earth element partition coefficients (such as La) are incompatible (D<1) in alkali-rich silicate melts and strongly compatible (D>>1) in alkali-poor melt compositions. From our experimental data we present an model that combines the influence of the crystal lattice on partitioning with the effect of melt composition on trace element partition coefficients. [1] Nakada, S. (1991) Am. Mineral. 76: 548-560 [2] Green, T.H. and Pearson, N.J. (1986) Chem. Geol. 55: 105-119 [3] Tiepolo, M.; Oberti, R. and Vannucci, R. (2002) Chem. Geol. 191: 105-119

Abundance, distribution and bioavailability of major and trace elements in surface sediments from the Cai River estuary and Nha Trang Bay (South China Sea, Vietnam)

NASA Astrophysics Data System (ADS)

Koukina, S. E.; Lobus, N. V.; Peresypkin, V. I.; Dara, O. M.; Smurov, A. V.

2017-11-01

Major (Si, Al, Fe, Ti, Mg, Ca, Na, K, S, P), minor (Mn) and trace (Li, V, Cr, Co, Ni, Cu, Zn, As, Sr, Zr, Mo, Cd, Ag, Sn, Sb, Cs, Ba, Hg, Pb, Bi and U) elements, their chemical forms and the mineral composition, organic matter (TOC) and carbonates (TIC) in surface sediments from the Cai River estuary and Nha Trang Bay were first determined along the salinity gradient. The abundance and ratio of major and trace elements in surface sediments are discussed in relation to the mineralogy, grain size, depositional conditions, reference background and SQG values. Most trace-element contents are at natural levels and are derived from the composition of rocks and soils in the watershed. A severe enrichment of Ag is most likely derived from metal-rich detrital heavy minerals such as Ag-sulfosalts. Along the salinity gradient, several zones of metal enrichment occur in surface sediments because of the geochemical fractionation of the riverine material. The parts of actually and potentially bioavailable forms (isolated by four single chemical reagent extractions) are most elevated for Mn and Pb (up to 36% and 32% of total content, respectively). The possible anthropogenic input of Pb in the region requires further study. Overall, the most bioavailable parts of trace elements are associated with easily soluble amorphous Fe and Mn oxyhydroxides. The sediments are primarily enriched with bioavailable metal forms in the riverine part of the estuary. Natural (such as turbidities) and human-generated (such as urban and industrial activities) pressures are shown to influence the abundance and speciation of potential contaminants and therefore change their bioavailability in this estuarine system.

Geochemical constraints on crustal anatexis: a case study from the Pan-African Damara granitoids of Namibia

NASA Astrophysics Data System (ADS)

McDermott, F.; Harris, N. B. W.; Hawkesworth, C. J.

1996-05-01

Major and trace element models of recently published vapour-absent mica dehydration melting experiments are used to identify granitoids generated by muscovite and biotite dehydration melting, and to distinguish between plagioclase-limited and biotite-limited, biotite dehydration melting. In the case of granitoids from the Pan-African Damara mobile belt (Namibia), many of the leucogranites and Salem-type granitoids may be modelled by biotite dehydration melting. The low Rb/Sr granitoids (e.g. Donkerhuk Onanis, Salem Onanis, Donkerhuk Nomatsaus, Salem Goas) probably reflect feldspar-limited, biotite dehydration melting (a pelitic source) whereas the high Rb/Sr suites (e.g. Bloedkoppie leucogranite, Stinkbank leucogranite, Salem Swakopmund, Leucocratic Stink bank granite) reflect biotite-limited, biotite dehydration melting (a greywacke source). Alaskites from the Damara belt have major element compositions which are consistent with muscovite dehydration melting, and their positive Eu anomalies are linked to high K2O reflecting K-feldspar entrainment. Combined Zr and LREE (light rare earth element) solubility models indicate that insufficient time (probably less than 104 years) had elapsed between melt generation and melt extraction to ensure that the alaskite melts attained their equilibrium concentrations of Zr and the LREEs. In contrast, the leucogranites and Salem-type granites have attained their equilibrium inventories of these trace elements. Combined Fe2O3 and MgO contents in some samples from two granitoids (the Salem Goas and Donkerhuk Onanis intrusions) are higher than those readily attainable by biotite dehydration melting indicating either: (1) that they contain a contribution from melts generated by incipient garnet breakdown or; (2) that they contain small amounts of an entrained ferromagnesian phase.

Preliminary geochemical results of corals from the Puerto Morelos Reef, Southeastern Mexico

NASA Astrophysics Data System (ADS)

Marquez, N.; Kasper, J.

2012-04-01

A microprobe (MB), major, trace and rare earth elements (REE) analyses were carried out in three coral species Acropora palmata, Acropora cervicornis and Gorgonia ventalina at Puerto Morelos, Reef, Southeastern Mexico. This was done to assess the degree in which the corals developed under the different chemical-physical natural and artificial conditions. The corals were cut at the top and middle and based upon the observations by using the MB analysis, results showed the highest concentrations of Ag, Cu, Cr, Ni, S, Sr, Zn y Zr in Gorgonia Ventalina suggesting an impact coming from the industrial discharges and/or rusting of boats in the area. The results of X-ray fluorescence analysis for major and trace elements showed that the Fe , Sr and Zr increase their content in the skeletons of Acropora palmata y Gorgonia ventalina also asociated with the presence of human activity since the area is composed mainly by carbonate source sediments. The rare earth elements (REE) analysis showed that the negative anomaly of Ce suggests a well oxygenated, highly oxidative modern shallow waters, and high nutrients related to suspended matter for Acropora Palmata, Acropora cervicornis y Gorgonia ventalina, The Positive Eu anomaly in the corals are due to the development of the reef linked to the concentration of waters enriched in La. The Nd/Yb ratio indicates a shallow water development for the corals. This is also supported by the Ce/Ce* vs. Pr/Pr* ratios that indicate shallow marine waters in the development of the three corals studied (Ce*= 0.5La+0.5Pr and Pr*= 0.5Ce+0.5Nd). Enrichment of heavy rare earth elements (Gd-Lu) in the corals may be associated with high pH values and CO, OH- ions in the sea water.

Immobile Trace Element Discrimination of Near-cogenetic Eruptions

NASA Astrophysics Data System (ADS)

Villa, I. M.

2015-12-01

A chemical diagram to discriminate individual magma batches in composite plutonic/volcanic complexes is proposed here: x = Y/Al, y = Zr/Ti. Both ratios are stable during weathering and low-grade metamorphism. Y/Al only depends on fractional crystallization of garnet, xenotime and monazite during magmatogenesis and the degree of partial melting. This already distinguishes individual magmas. Zr/Ti is modified by other phases (rutile, titanite, zircon, ilmenite, biotite, etc) that neither accommodate nor fractionate trivalent cations and provides a totally independent perspective on magmatogenesis. The Y/Al-Zr/Ti plot has no relation to tectonic setting (convergent, rift, intraplate, etc) and is not designed to distinguish lines of descent (calc-alkaline, transitional, etc). Instead, it can discriminate at a very fine scale lavas that share a common regional origin and are therefore confused in classic tectonic discrimination plots. Disentangling individual magma batches is inaccessible to global modeling but important to chronostratigraphers. Application to two well studied examples, Adamello (Alps) and North Anatolia, reproduces known consanguinity and rejects a few dubious ones.

The effects of sorting by aeolian processes on the geochemical characteristics of surface materials: a wind tunnel experiment

NASA Astrophysics Data System (ADS)

Wang, Xunming; Lang, Lili; Hua, Ting; Zhang, Caixia; Li, Hui

2018-03-01

The geochemical characteristics of aeolian and surface materials in potential source areas of dust are frequently employed in environmental reconstructions as proxies of past climate and as source tracers of aeolian sediments deposited in downwind areas. However, variations in the geochemical characteristics of these aeolian deposits that result from near-surface winds are currently poorly understood. In this study, we collected surface samples from the Ala Shan Plateau (a major potential dust source area in Central Asia) to determine the influence of aeolian processes on the geochemical characteristics of aeolian transported materials. Correlation analyses show that compared with surface materials, the elements in transported materials (e.g., Cu, As, Pb, Mn, Zn, Al, Ca, Fe, Ga, K, Mg, P, Rb, Co, Cr, Na, Nb, Si, and Zr) were subjected to significant sorting by aeolian processes, and the sorting also varied among different particle size fractions and elements. Variations in wind velocity were significantly correlated with the contents of Cr, Ga, Sr, Ca, Y, Nd, Zr, Nb, Ba, and Al, and with the Zr/Al, Zr/Rb, K/Ca, Sr/Ca, Rb/Sr, and Ca/Al ratios. Given the great variation in the geochemical characteristics of materials transported under different aeolian processes relative to those of the source materials, these results indicate that considerable uncertainty may be introduced to analyses by using surface materials to trace the potential source areas of aeolian deposits that accumulate in downwind areas.

Trace element analyses of fluid-bearing diamonds from Jwaneng, Botswana

NASA Astrophysics Data System (ADS)

Schrauder, Marcus; Koeberl, Christian; Navon, Oded

1996-12-01

Fibrous diamonds from Botswana contain abundant micro-inclusions, which represent syngenetic mantle fluids under high pressure. The major element composition of the fluids within individual diamonds was found to be uniform, but a significant compositional variation exists between different diamond specimens. The composition of the fluids varies between a carbonatitic and a hydrous endmember. To constrain the composition of fluids in the mantle, the trace element contents of thirteen micro-inclusion-bearing fibrous diamonds from Botswana was studied using neutron activation analysis. The concentrations of incompatible elements (including K, Na, Br, Rb, Sr, Zr, Cs, Ba, Hf, Ta, Th, U, and the LREEs) in the fluids are higher than those of mantle-derived rocks and melt inclusions. The compatible elements (e.g., Cr, Co, Ni) have abundances that are similar to those of the primitive mantle. The concentrations of most trace elements decrease by a factor of two from the carbonate-rich fluids to the hydrous fluids. Several models may explain the observed elemental variations. Minerals in equilibrium with the fluid were most likely enriched in incompatible elements, which does not agree with derivation of the fluids by partial melting of common peridotites or eclogites. Fractional crystallization of a kimberlite-like magma at depth may yield carbonatitic fluids with low mg numbers (atomic ratio [Mg/(Mg+Fe)]) and high trace element contents. Fractionation of carbonates and additional phases (e.g., rutile, apatite, zircon) may, in general, explain the concentrations of incompatible elements in the fluids, which preferably partition into these phases. Alternatively, mixing of fluids with compositions similar to those of the two endmembers may explain the observed variation of the elemental contents. The fluids in fibrous diamonds might have equilibrated with mineral inclusions in eclogitic diamonds, while peridotitic diamonds do not show evidence of interaction with these fluids. The chemical composition of the fluids in fibrous diamonds indicates that, at p, T conditions that are characteristic for diamond formation, carbonatitic and hydrous fluids are efficient carriers of incompatible elements.

Comparative uptake of trace elements in vines and olive trees over calcareous soils in western La Mancha

NASA Astrophysics Data System (ADS)

Ángel Amorós, José; Higueras, Pablo; Pérez-de-los-Reyes, Caridad; Jesús García, Francisco; Villaseñor, Begoña; Bravo, Sandra; Losilla, María Luisa; María Moreno, Marta

2014-05-01

Grapevine (Vitis vinifera L.) and olive-tree (Olea europea L.) are very important cultures in Castilla-La Mancha for its extension and contribution to the regional economy. This study was carried out in the municipality of Carrión de Calatrava (Ciudad Real) where the variability of soils of different geological origin, with different evolutions giving a great diversity of soils. The metabolism of trace elements in plants has been extensively studied although each soil-plant system must be investigated, especially since small variations in composition can lead to marked differences. It can be stated that the composition of the plant reflects the environment where it is cultivated and the products of the plant (leaves, fruits, juices, etc…) will be influenced by the composition of the soil. The main aim of the work was to compare the uptake of 24 trace elements in grapevine and olive-tree cultivated in the same soil. Samples from surface soils and plant material (leaf) have been analyzed by X-ray fluorescence, obtaining trace elements in mg/kg. It can be concluded that the leaves of grapevines in the studied plots have shown content in elements: -Similar to the olive-tree in case of: Co, Ga, Y, Ta, Th, U y Nd. -Over to the olive-tree in: Sc, V, Cr, Ni, Rb, Sr, Zr, Nb, Ba, La, Ce, Hf y W. -Below to the olive-tree in: Cu, Zn, Cs y Pb. Keywords: woody culture soils, mineral nutrition, X-ray fluorescence.

The Middle Triassic evolution of the Bangong-Nujiang Tethyan Ocean: evidence from analyses of OIB-type basalts and OIB-derived phonolites in northern Tibet

NASA Astrophysics Data System (ADS)

Fan, Jian-Jun; Li, Cai; Liu, Jin-Heng; Wang, Ming; Liu, Yi-Ming; Xie, Chao-Ming

2017-12-01

In this paper, we present new major and trace element chemical data for the basalts and phonolites of the Nare ocean island fragment (NaOI), as well as zircon U-Pb age data and Hf isotope compositions for the NaOI phonolites in the middle segment of the Bangong-Nujiang Suture Zone, northern Tibet. Our aim is to assess the genesis of these rocks and to reconstruct the Middle Triassic evolution of the Bangong-Nujiang Tethyan Ocean (BNTO). The NaOI retains an ocean island-type double-layered structure comprising a basaltic basement and an oceanic sedimentary cover sequence (conglomerate and limestone, the latter accompanied by layers of erupted phonolite near the top of the sequence). The basalts in the NaOI are enriched in light rare earth elements and high field strength elements (Nb, Ta, Zr, Hf, and Ti), and they exhibit chondrite-normalized REE patterns and primitive mantle-normalized trace element patterns similar to those of ocean island basalts. Taking into consideration their high Dy/Yb, Sm/Yb, and La/Sm ratios, we conclude that the NaOI basalts were derived from the partial melting of garnet peridotite in the mantle. The NaOI phonolites have LREE-enriched chondrite-normalized REE patterns with negative Eu anomalies (Eu/Eu* = 0.41-0.43) and primitive mantle-normalized trace element patterns with enrichments in Nb, Ta, Zr, and Hf, and depletions in Ba, U, Sr, P, and Ti. Given the high contents of Nb (172-256 ppm), Ta (11.8-16.0 ppm), Zr (927-1117 ppm), and Hf (20.8-26.9 ppm), and the very low contents of MgO (0.11-0.25 wt%), the very low Mg# values (5-10), and the near-zero contents of Cr (1.27-7.59 ppm), Ni (0.43-7.19 ppm), and Co (0.11-0.38 ppm), and the small and homogeneously positive ɛ Hf(t) values (+ 4.9 to + 9.5), we infer that the NaOI phonolites were formed by the fractional crystallization of an OIB-derived mafic parent magma. The phonolites of the NaOI contain zircons that yielded U-Pb ages of 239 and 242 Ma, indicating that the NaOI formed during the Middle Triassic. These data, combined with data from modern ocean islands (e.g., Canary Islands, Cape Verde, Fernando de Noronha, Tristan da Cunha, and Gough in the Atlantic Ocean, and Society and Austral-Cook in the Pacific Ocean), lead us to infer that the BNTO was open for a long time before the Middle Triassic, and that the ocean had already developed into a mature ocean with a thick oceanic lithosphere by at least the Middle Triassic.

Geochemistry of post-spreading lavas from fossil Mathematician and Galapagos spreading axes, revisited

NASA Astrophysics Data System (ADS)

Tian, L.; Castillo, P. R.; Hilton, D. R.

2010-12-01

The Mathematician Ridge, located west of the northern end of the EPR at about 10-20°N, 110°W, was abandoned during the Pliocene when the Pacific plate captured the Mathematician microplate. The Galapagos Rise, located east of the southern segment of the EPR at about 10-18°S, 95°W, ceased spreading after the Late Miocene capture of the Bauer microplate by the Nazca plate. Here we report new major and trace element and Sr, Nd and Pb isotope data for lavas dredged from seamounts and volcanic ridges along the crest of Mathematician Ridge [Batiza and Vanko, J. Petrol. 26, 1985] and from narrow volcanic ridges built along extinct segments of the Galapagos Rise [Batiza et al., Mar. Geol. 49, 1982]. These lavas consist predominantly of alkalic basalts and their differentiates, similar to the post-spreading alkalic lava series in other fossil spreading axes (e.g., Davidson Seamount, Guide Seamount, Socorro Island, and fossil spreading axes off Baja California Sur) and alkalic lavas from near-ridge seamounts in the eastern Pacific [Castillo et al., G3 11, 2010; Tian et al., sub. to G3]. Collectively, the alkalic lavas have higher incompatible trace element contents and highly/moderately incompatible trace element ratios (e.g., Ba/Zr >1.3, La/Sm >2.7 and Nb/Zr >0.14) than EPR basalts, and are similar to average alkalic OIB. They also have similar 87Sr/86Sr (0.7027 - 0.7037), 143Nd/144Nd (0.51289 - 0.51306) and 206Pb/204Pb (18.70 - 19.84) compositions, which overlap with geochemically enriched (E-) MORB and ~depleted OIB from major hotspot volcanic chains such as Galapagos, Hawaii and Iceland. The new data suggest that intraplate lavas from fossil spreading axes and non-hotspot seamounts in the eastern Pacific share a common enriched source which is geographically dispersed in the upper mantle.

Major and EDXRF Trace Element Chemical Analyses of Volcanic Rocks from Lassen Volcanic National Park and Vicinity, California

USGS Publications Warehouse

Clynne, Michael A.; Muffler, L.J.P.; Siems, D.F.; Taggart, J.E.; Bruggman, Peggy

2008-01-01

This open-file report presents WDXRF major-element chemical data for late Pliocene to Holocene volcanic rocks collected from Lassen Volcanic National Park and vicinity, California. Data for Rb, Sr, Ba, Y, Zr, Nb, Ni, Cr, Zn and Cu obtained by EDXRF are included for many samples. Data are presented in an EXCEL spreadsheet and are keyed to rock units as displayed on the Geologic Map of Lassen Volcanic National Park and vicinity (Clynne and Muffler, in press). Location of the samples is given in latitude and longitude in degrees and decimal minutes and in decimal degrees.

Development of a mixed seawater-hydrothermal fluid geochemical signature during alteration of volcanic rocks in the Archean (∼2.7 Ga) Abitibi Greenstone Belt, Canada

NASA Astrophysics Data System (ADS)

Brengman, Latisha A.; Fedo, Christopher M.

2018-04-01

We investigated a group of silicified volcanic rocks from the ∼2.72 Ga Hunter Mine Group (HMG), Abitibi Greenstone Belt, Canada, in order to document progressive compositional change associated with alteration in a subaqueous caldera system. Rocks of the HMG divide into three groups based on mineralogy and texture for petrographic and geochemical analyses. Volcanic features (phenocrysts, pseudomorphs after primary glass shards, lapilli, volcanic clasts) are preserved in all groups, despite changing mineralogy from primarily quartz, feldspar, chlorite (Groups 1 and 2), to quartz, hematite and carbonate (Groups 2 and 3). Compositionally, Group 1 rocks resemble volcanic rocks in the region, while Group 2 and 3 rocks show a change in mineralogy to iron, silica, and carbonate minerals, which is associated with depletion of many major and trace elements associated with volcanic rocks (Al2O3, Na2O, K2O, Zr). In addition, rare earth elements display a clear progression from volcanic signatures in Group 1 (PrSN/YbSN = 1.7-2.96, EuSN/EuSN∗ = 0.84-1.72, Y/Ho = 25.20-27.41, LaSN/LaSN∗ = 0.97-1.29, and Zr/Hf = 38.38-42.09) to transitional mixed volcanic, hydrothermal, and seawater signatures in Group 2 (PrSN/YbSN 1.33-2.89, EuSN/EuSN∗ 1.33-2.5, Y/Ho = 23.94-30, LaSN/LaSN∗ 0.93-1.34, and Zr/Hf = 40-70), to mixed hydrothermal and seawater signatures in Group 3 (PrSN/YbSN 0.62-2.88, EuSN/EuSN∗ 1.30-7.15, LaSN/LaSN∗ 1.02-1.86, Y/Ho = 25.56-55, and Zr/Hf = 35-50). We interpret that silicification of volcanic rocks (Group 1) produced transitional altered volcanic rocks (Group 2), and siliceous and jaspilitic rocks (Group 3), based on preservation of delicate volcanic features. Building on this explanation, we interpret that major, trace- and rare-earth element mobility occurred during the process of silicification, during which siliceous and jaspilitic rocks (Group 3) acquired aspects of the rare-earth element geochemical signatures of marine chemical precipitates. We conclude that seafloor silicification in hydrothermal depositional settings is capable of producing rocks that resemble marine chemical precipitates such as banded iron formation, and could be a process that is widespread in the Archean. Consequently, because silicified volcanic rocks from the HMG possess mixed seawater and hydrothermal rare-earth element characteristics similar to Archean iron formations and cherts, we suggest caution must be exercised when interpreting the geochemical information preserved in metamorphosed rocks where original genesis is unknown.

Distribution of Trace Metals in a Tanzanian Andosol: A Combined Bulk and Leach Study

NASA Astrophysics Data System (ADS)

Little, M. G.

2005-12-01

Here is presented data from a sequential extraction scheme based on the Bureau Commun de Reference (BCR) applied to an andosol from Mt. Meru in northern Tanzania. This is a study into the origins, fractionation, and fate of 'potentially toxic elements' (PTE) and other trace elements. The elemental composition of four extracts, water soluble (WAT), carbonate and exchangeable (CARB), reducible oxides (OX), and organic (ORG), and the bulk soil were determined via ICP-MS and corrected for loss on ignition. We calculated the net elemental mass change using Zr and Hf as immobile elements. This calculated mass change was compared to the sum of all four leaches. Co, Mg, Ni, Zn, Cd, Tl are the only elements that show a positive correlation between the calculated net change based on Zr/Hf and the sum of all four leaches. Of these elements, Zn shows its greatest bulk enrichment at the surface and declines with depth. Conversely, Tl is enriched throughout the soil column, but increases in concentration in both the bulk and CARB fraction with depth. The other elements, Co, Ni, and Cd, are most enriched in the 80-120cm depth range where P and Fe are at their highest concentrations. These observations suggest that additional Co, Mg, Ni, Zn, Cd, and Tl were incorporated into the soil after initial weathering of the bedrock protolith; however, these elements redistributed themselves non-uniformly throughout the soil column. Sc and the REE's show increases in the CARB fraction with depth and Sc, Co, and the REE's show a clear increase in the OX fractions with depth. As much as 25% of the REE's and Co below 120 cm is in the OX leach. Additionally, Sr/Ca ratios in the CARB leach suggest that the source material for the carbonate soil fraction is the bedrock above 140cm and a different, high Sr/Ca source below 140 cm. Therefore, it is likely that exogenous material was added throughout the soil column, but from different sources above and below 120-140 cm depth.

Oxidative mobilization of cerium and uranium and enhanced release of "immobile" high field strength elements from igneous rocks in the presence of the biogenic siderophore desferrioxamine B

NASA Astrophysics Data System (ADS)

Kraemer, Dennis; Kopf, Sebastian; Bau, Michael

2015-09-01

Polyvalent trace elements such as the high field strength elements (HFSE) are commonly considered rather immobile during low-temperature water-rock interaction. Hence, they have become diagnostic tools that are widely applied in geochemical studies. We present results of batch leaching experiments focused on the mobilization of certain HFSE (Y, Zr, Hf, Th, U and rare earth elements) from mafic, intermediate and felsic igneous rocks in the presence and absence, respectively, of the siderophore desferrioxamine B (DFOB). Our data show that DFOB strongly enhances the mobility of these trace elements during low-temperature water-rock interaction. The presence of DFOB produces two distinct features in the Rare Earths and Yttrium (REY) patterns of leaching solutions, regardless of the mineralogical and chemical composition or the texture of the rock type studied. Bulk rock-normalized REY patterns of leaching solutions with DFOB show (i) a very distinct positive Ce anomaly and (ii) depletion of La and other light REY relative to the middle REY, with a concave downward pattern between La and Sm. These features are not observed in experiments with hydrochloric acid, acetic acid or deionized water. In DFOB-bearing leaching solutions Ce and U are decoupled from and selectively enriched relative to light REY and Th, respectively, due to oxidation to Ce(IV) and U(VI). Oxidation of Ce3+ and U4+ is promoted by the significantly higher stability of the Ce(IV) and U(VI) DFOB complexes as compared to the Ce(III) and U(IV) DFOB complexes. This is similar to the relationship between the Ce(IV)- and Ce(III)-pentacarbonate complexes that cause positive Ce anomalies in alkaline lakes. However, while formation of Ce(IV) carbonate complexes is confined to alkaline environments, Ce(IV) DFOB complexes may produce positive Ce anomalies even in mildly acidic and near-neutral natural waters. Siderophore-promoted dissolution processes also significantly enhance mobility of other 'immobile' HFSE and may not only cause or modify Ce anomalies and Th-U fractionation, but also mobilization of and fractionation between Zr, Hf, Th and redox-insensitive REY during weathering, pedogenesis, diagenesis and incongruent dissolution of particles in seawater and freshwater. Siderophores may significantly affect the use of HFSE as geochemical tools. Concave downward light REY patterns may be used as a biosignature for water-rock interaction in the presence of siderophores. Enhanced and preferential mobilization of U relative to Th in the presence of siderophores may produce Th-U signals comparable to those indicative of weathering under oxidized conditions, which might constrain the use of U concentrations and Th/U ratios as a paleoredox-proxy. The enhanced mobilization of Zr and especially Hf from igneous rocks in the presence of DFOB might have implications for the use of the latter as a tracer for the impact of continental weathering on seawater chemistry. Because siderophore complexes affect the particle-reactivity of Hf and Zr, they may prevent effective removal of terrigenous Hf and Zr during aggregation/coagulation of riverine particles in estuaries. Siderophore-promoted solubilization and stabilization might hence be an additional way to transport continental Hf and Zr to the oceans. Furthermore, siderophore-enhanced mobilization may also have implications for the remediation techniques employed to immobilize HFSE such as U, Th and REY, at nuclear waste and reprocessing sites and at REY ore processing plants, where soils are commonly contaminated with these (sometimes radioactive) heavy metals.

Micro-PIXE analysis of silicate reference standards

USGS Publications Warehouse

Czamanske, G.K.; Sisson, T.W.; Campbell, J.L.; Teesdale, W.J.

1993-01-01

The accuracy and precision of the University of Guelph proton microprobe have been evaluated through trace-element analysis of well-characterized silicate glasses and minerals, including BHVO-1 glass, Kakanui augite and hornblende, and ten other natural samples of volcanic glass, amphibole, pyroxene, and garnet. Using the 2.39 wt% Mo in a NIST steel as the standard, excellent precision and agreement between reported and analyzed abundances were obtained for Fe, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, and Nb. -from Authors

Using Elemental Abundances and Petrophysical Properties to Trace Sediment Transport in the Hudson River

NASA Astrophysics Data System (ADS)

Chang, C.; Kenna, T. C.; Nitsche, F. O.

2016-12-01

The IPCC predicts that the frequency and severity of storms worldwide will increase due to climate change, a growing concern for the highly populated coastal areas near the Hudson River estuary. Storms have the potential to change the river's sediment budget, and it is necessary to update the current understanding of the effect of storms on sediment dynamics. In 2011, Tropical Storm Lee and Hurricane Irene delivered over 2.7 million tons of sediment to the Hudson River including over 1.5 million tons from the Mohawk River, a freshwater tributary, in addition to record amounts contributed from other major tributaries. The goals of this project are to use sediment elemental compositions to trace the major tributaries contributing to this storm-deposited sediment and to determine where sediment is accumulating as a result of storm activity. Chemical analysis of over 800 archived sediment samples are compiled to provide a pre-storm background level. These samples are compared to newly deposited sediment and material from specific tributaries. Elemental abundances (K, Ca, Ti, Cr, Mn, Fe, Co, Cu, Zn, Rb, Sr, Zr, Pb, and U) are measured using a field portable X-Ray Fluorescence (XRF) unit and core scanning XRF unit. Bulk matrix density is measured using a pycnometer. The measurements are used to identify elemental signatures from tributary sediment and to trace the influence of specific tributaries on deposition through the river. Our results suggests measureable signatures in sediment from individual tributaries. The Mohawk River contributes high concentrations of Ca due to the calcite deposits in its watershed. XRF measurements also show the effect of human activity on sediment deposition; variations in Rb and Zr indicate changes in deposition due to dredging in Haverstraw Bay. The salt wedge front, where ocean and fresh water meets is evident in areas of below average matrix density. This project shows significant geochemical variability between sediment from different areas of the river, and indicates that XRF can be used to track sediment sources and deposition.

Geochemical fingerprinting and source discrimination in soils at the continental scale

NASA Astrophysics Data System (ADS)

Negrel, Philippe; Sadeghi, Martiya; Ladenberger, Anna; Birke, Manfred; Reimann, Clemens

2014-05-01

Agricultural soil (Ap-horizon, 0-20 cm) samples were collected from a large part of Europe (33 countries, 5.6 million km2) at an average density of 1 sample site per 2500 km2. The resulting 2108 soil samples were air dried, sieved to <2 mm, milled and analysed for their major and trace element concentrations by wavelength dispersive X-ray fluorescence spectrometry (WD-XRF). The main goal of this study is to provide a global view of element mobility and source rocks at the continent scale, either by reference to crustal evolution or normalized patterns of element mobility during weathering processes. The survey area includes several sedimentary basins with different geological history, developed in different climate zones and landscapes and with different land use. In order to normalize the chemical composition of soils, mean values and standard deviation of the selected elements have been checked against values for the upper continental crust (UCC). Some elements turned out to be enriched relative to the UCC (Al, P, Zr, Pb) whereas others, like Mg, Na, Sr and Pb were depleted with regards to the variation represented by the standard deviation. The concept of UCC extended normalization patterns have been further used for the selected elements. The mean value of Rb, K, Y, Ti, Al, Si, Zr, Ce and Fe are very close to the UCC model even if standard deviation suggests slight enrichment or depletion, and Zr shows the best fit with the UCC model using both mean value and standard deviation. Lead and Cr are enriched in European soils when compared to UCC but their standard deviation values show very large variations, particularly towards very low values, which can be interpreted as a lithological effect. Element variability has been explored by looking at the variations using indicator elements. Soil data have been converted into Al-normalized enrichment factors and Na was applied as normalizing element for studying provenance source taking into account the main lithologies of the UCC. This latter normalization highlighted variations related to the soluble and insoluble behavior of some elements (K, Rb versus Ti, Al, Si, V, Y, Zr, Ba, and La, respectively), their reactivity (Fe, Mn, Zn), association with carbonates (Ca and Sr) and with phosphates (P and Ce). The maps of normalized composition revealed some problems with use of classical element ratios due to genetical differences in composition of parent material reflected, for example, in large differences in titanium content in bedrock and soil throughout the Europe.

Experimental determination of trace-element partitioning between pargasite and a synthetic hydrous andesitic melt

NASA Astrophysics Data System (ADS)

Brenan, J. M.; Shaw, H. F.; Ryerson, F. J.; Phinney, D. L.

1995-10-01

In order to more fully establish a basis for quantifying the role of amphibole in trace-element fractionation processes, we have measured pargasite/silicate melt partitioning of a variety of trace elements (Rb, Ba, Nb, Ta, Hf, Zr, Ce, Nd, Sm, Yb), including the first published values for U, Th and Pb. Experiments conducted at 1000°C and 1.5 GPa yielded large crystals free of compositional zoning. Partition coefficients were found to be constant at total concentrations ranging from ˜ 1 to > 100 ppm, indicating Henry's Law is oparative over this interval. Comparison of partition coefficients measured in this study with previous determinations yields good agreement for similar compositions at comparable pressure and temperature. The compatibility of U, Th and Pb in amphibole decreases in the order Pb > Th > U. Partial melting or fractional crystallization of amphibole-bearing assemblages will therefore result in the generation of excesses in 238U activity relative to 230Th, similar in magnitude to that produced by clinopyroxene. The compatibility of Pb in amphibole relative to U or Th indicates that melt generation in the presence of residual amphibole will result in the long-term enrichment in Pb relative to U or Th in the residue. This process is therefore incapable of producing the depletion in Pb relative to U or Th inferred from the Pb isotopic composition of MORB and OIB. Comparison of partition coefficients measured in this study with previous values for clinopyroxene allows some distinction to be made between expected trace-element fractionations produced during dry (cpx present) and wet (cpx + amphibole present) melting. Rb, Ba, Nb and Ta are dramatically less compatible in clinopyroxene than in amphibole, whereas Th, U, Hf and Zr have similar compatibilities in both phases. Interelement fractionations, such as DNb/DBa are also different for clinopyroxene and amphibole. Changes in certain ratios, such as Ba/Nb, Ba/Th, and Nb/Th within comagmatic suites may therefore offer a means to discern the loss of amphibole from the melting assemblage. Elastic strain theory is applied to the partitioning data after the approaches of Beattie and Blundy and Wood and is used to predict amphibole/melt partition coefficients at conditions of P, T and composition other than those employed in this study. Given values of DCa, DTi and DK from previous partitioning studies, this approach yields amphibole/melt trace-element partition coefficients that reproduce measured values from the literature to within 40-45%. This degree of reproducibility is considered reasonable given that model parameters are derived from partitioning relations involving iron- and potassium-free amphibole.

Uranium and minor-element partitioning in Fe-Ti oxides and zircon from partially melted granodiorite, Crater Lake, Oregon

USGS Publications Warehouse

Tourrette, T.Z.L.; Burnett, D.S.; Bacon, C.R.

1991-01-01

Crystal-liquid partitioning in Fe-Ti oxides and zircon was studied in partially melted granodiorite blocks ejected during the climactic eruption of Mt. Mazama (Crater Lake), Oregon. The blocks, which contain up to 33% rhyolite glass (75 wt% SiO2), are interpreted to be portions of the magma chamber walls that were torn off during eruption. The glass is clear and well homogenized for all measured elements except Zr. Results for Fe-Ti oxides give DUoxide/liq ??? 0.1. Partitioning of Mg, Mn, Al, Si, V, and Cr in Fe-Ti oxides indicates that grains surrounded by glass are moderately well equilibrated with the melt for many of the minor elements, while those that are inclusions in relict plagioclase are not. Uranium and ytterbium inhomogeneities in zircons indicate that the zircons have only partially equilibrated with the melt and that uranium appears to have been diffusing out of the zircons faster than the zircons were dissolving. Minimum U, Y, and P concentrations in zircons give maximum DUzrc/liq = 13,DYzrc/liq = 23, and DPzrc/liq = 1, but these are considerably lower than reported by other workers for U and Y. Based on our measurements and given their low abundances in most rocks, Fe-Ti oxides probably do not play a major role in U-Th fractionation during partial melting. The partial melts were undersaturated with zircon and apatite, but both phases are present in our samples. This demonstrates an actual case of non-equilibrium source retention of accessory phases, which in general could be an important trace-element fractionation mechanism. Our results do not support the hypothesis that liquid structure is the dominant factor controlling trace-element partitioning in high-silica rhyolites. Rough calculations based on Zr gradients in the glass indicate that the samples could have been partially molten for 800 to 8000 years. ?? 1991.

Effects of Laser Power Level on Microstructural Properties and Phase Composition of Laser-Clad Fluorapatite/Zirconia Composite Coatings on Ti6Al4V Substrates.

PubMed

Chien, Chi-Sheng; Liu, Cheng-Wei; Kuo, Tsung-Yuan

2016-05-17

Hydroxyapatite (HA) is one of the most commonly used materials for the coating of bioceramic titanium (Ti) alloys. However, HA has poor mechanical properties and a low bonding strength. Accordingly, the present study replaces HA with a composite coating material consisting of fluorapatite (FA) and 20 wt % yttria (3 mol %) stabilized zirconia (ZrO₂, 3Y-TZP). The FA/ZrO₂ coatings are deposited on Ti6Al4V substrates using a Nd:YAG laser cladding system with laser powers and travel speeds of 400 W/200 mm/min, 800 W/400 mm/min, and 1200 W/600 mm/min, respectively. The experimental results show that a significant inter-diffusion of the alloying elements occurs between the coating layer (CL) and the transition layer (TL). Consequently, a strong metallurgical bond is formed between them. During the cladding process, the ZrO₂ is completely decomposed, while the FA is partially decomposed. As a result, the CLs of all the specimens consist mainly of FA, Ca₄(PO₄)₂O (TTCP), CaF₂, CaZrO₃, CaTiO₃ and monoclinic phase ZrO₂ (m-ZrO₂), together with a small amount of θ-Al₂O₃. As the laser power is increased, CaO, CaCO₃ and trace amounts of tetragonal phase ZrO₂ (t-ZrO₂) also appear. As the laser power increases from 400 to 800 W, the CL hardness also increases as a result of microstructural refinement and densification. However, at the highest laser power of 1200 W, the CL hardness reduces significantly due to the formation of large amounts of relatively soft CaO and CaCO₃ phase.

Crystallization conditions and controls on trace element residence in the main minerals from the Pedra Branca Syenite, Brazil: An electron microprobe and LA-ICPMS study

NASA Astrophysics Data System (ADS)

Carvalho, Bruna Borges; Janasi, Valdecir de Assis

2012-11-01

Major and trace-element microanalyses of the main minerals from the 610 Ma Pedra Branca Syenite, southeast Brazil, allow inferences on intensive parameters of magmatic crystallization and on the partition of trace-elements among these minerals, with important implications for the petrogenetic evolution of the pluton. Two main syenite types make up the pluton, a quartz-free syenite with tabular alkali feldspar (laminated silica-saturated syenite, LSS, with Na-rich augite + phlogopite + hematite + magnetite + titanite + apatite) and a quartz-bearing syenite (laminated silica-oversaturated syenite, LSO, with scarce corroded plagioclase plus diopside + biotite ± hornblende + ilmenite ± magnetite + titanite + apatite). Both types share a remarkable enrichment in incompatible elements as K, Ba, Sr, P and LREE. Apatite saturation temperatures of ~ 1060-1090 °C are the best estimates of liquidus, whereas the pressure of emplacement, based on Al-in-hornblende barometry, is estimated as 3.3 to 4.8 kbar. Although both units crystallized under oxidizing conditions, oxygen fugacity was probably higher in LSS, as shown by higher mg# of the mafic minerals and higher hematite contents in Hem-Ilmss. In contrast with the Ca-bearing alkali-feldspar from LSO, which hosts most of the whole-rock Sr and Pb, virtually Ca-free alkali-feldspar from LSS hosts ~ 50% of whole-rock Sr and ~ 80% of Pb, the remainder of these elements being shared by apatite, pyroxene and titanite. This contrast reflects a strong crystal-chemical control, whereby a higher proportion of an element with similar ratio and charge (Ca2 +) enhances the residence of Sr and Pb in the M-site of alkali feldspar. The more alkaline character of the LSS magma is inferred to have inhibited zircon saturation; Zr + Hf remained in solution until late in the crystallization, and were mostly accommodated in the structure of Ca-Na pyroxene and titanite, which are one order of magnitude richer in these elements compared to the same minerals in LSO, where most of Zr and Hf are inferred to reside in zircon. The REE, Th and U reside mostly in titanite and apatite; D(REE)Tit/Ap raises steadily from 1 to 6 from La to Tb then remains constant up to Lu in the LSO sample; these values are about half as much in the LSS sample, where lower contents of incompatible elements in titanite are attributed to its greater modal abundance and earlier crystallization.

Geochemical constraints on depth of origin of oceanic carbonatites: The Cape Verde case

NASA Astrophysics Data System (ADS)

Doucelance, Régis; Hammouda, Tahar; Moreira, Manuel; Martins, João C.

2010-12-01

We present new Sr-Nd isotope compositions together with major- and trace element concentrations measured for whole rocks and mineral separate phases (apatite, biotite and calcite) from fifteen Cape Verde oceanic carbonatites (Atlantic Ocean). Trace element patterns of calcio- and magnesio-carbonatites present a strong depletion in K, Hf, Zr and Ti and an overall enrichment in Sr and REE relative to Cape Verde basalts, arguing for distinct source components between carbonatites and basalts. Sr and Nd isotopic ratios show small, but significant variations defining a binary mixing between a depleted end-member with unradiogenic Sr and radiogenic Nd values and a ''enriched'' end-member compatible with old marine carbonates. We interpret the depleted end-member as the Cape Verde oceanic lithosphere by comparison with previous studies on Cape Verde basalts. We thus propose that oceanic carbonatites are resulting from the interaction of a deep rooted mantle plume carrying a lower 4He/ 3He signature from the lower mantle and a carbonated metasomatized lithosphere, which by low degree melting produced carbonatite magmas. Sr-Nd compositions and trace element patterns of carbonatites argue in favor of a metasomatic agent originating from partial melting of recycled, carbonated oceanic crust. We have successfully reproduced the main geochemical features of this model using a Monte-Carlo-type simulation.

Single-step solubilization of milk samples with N,N-dimethylformamide for inductively coupled plasma-mass spectrometry analysis and classification based on their elemental composition.

PubMed

Azcarate, Silvana M; Savio, Marianela; Smichowski, Patricia; Martinez, Luis D; Camiña, José M; Gil, Raúl A

2015-10-01

A single-step procedure for trace elements analysis of milk samples is presented. Solubilization with small amounts of dymethylformamide (DMF) was assayed prior to inductively coupled plasma mass spectrometry (ICPMS) detection with a high efficiency sample introduction system. All main instrumental conditions were optimized in order to readily introduce the samples without matrix elimination. In order to assess and mitigate matrix effects in the determination of As, Cd, Co, Cu, Eu, Ga, Gd, Ge, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sm, S, Sr, Ta, Tb, V, Zn, and Zr, matrix matching calibration with (103)Rh as internal standard (IS) was performed. The obtained limits of detection were between 0.68 (Tb) and 30 (Zn) μg L(-1). For accuracy verification, certified Skim milk powder reference material (BCR 063R) was employed. The developed method was applied to trace elements analysis of commercially available milks. Principal components analysis was used to correlate the content of trace metals with the kind of milk, obtaining a classification according to adults, baby or baby fortified milks. The outcomes highlight a simple and fast approach that could be trustworthy for routine analysis, quality control and traceability of milks. Copyright © 2015 Elsevier B.V. All rights reserved.

Geochemical characterization of the largest upland lake of the Brazilian Amazonia: Impact of provenance and processes

NASA Astrophysics Data System (ADS)

Sahoo, Prafulla Kumar; Guimarães, José Tasso Felix; Souza-Filho, Pedro Walfir Martins; da Silva, Marcio Sousa; Nascimento, Wilson, Júnior; Powell, Mike A.; Reis, Luiza Santos; Pessenda, Luiz Carlos Ruiz; Rodrigues, Tarcísio Magevski; da Silva, Delmo Fonseca; Costa, Vladimir Eliodoro

2017-12-01

Lake Três Irmãs (LTI), the largest upland lake in the Brazilian Amazonia, located in Serra dos Carajás, was characterized using multi-elemental and isotope geochemistry (δ13C and δ15N) to understand the significance of organic and inorganic sources, weathering and sedimentary processes on the distribution of elements in lake bottom (surficial) sediments. Carbon and nitrogen isotopes from sedimentary organic matter suggest C3 terrestrial plants (forests > canga vegetation), macrophytes and freshwater DOC as the main sources. Sediments are depleted in most of the major oxides (except Fe2O3 and P2O5) when compared to upper continental crust (UCC) and their spatial distribution is highly influenced by catchment lithology. Principal Component Analysis revealed that most of the trace elements (Ba, Sr, Rb, Sc, Th, U, Zr, Hf, Nb, Y, V, Cr, Ga, Co, Ni) and REEs are closely correlated with Al and Ti (PC1; Group-1), so their redistribution is less influenced by post-depositional process. This is due to their relative immobility and being hosted by Al-bearing minerals during laterization. High Chemical Index of Alteration (CIA), Mafic Index of Alteration (MIA) and Index of Laterization (IOL) values indicate intense chemical weathering at source areas, but the weathering transformation was better quantified by IOL. A-CN-K plot along with elemental ratios (Al/K, Ti/K, Ti/Zr, La/Al, Cr/Th, Co/Th, La/Sm, La/Gd, Zr/Y, and Eu/Eu*) as well as chondrite-normalized REE patterns show that the detritic sediments are mainly sourced from ferruginous laterites and soils in the catchment, which may have characteristics similar to mafic rocks.

Geochemistry and mineralogy of the older (> 40 ka) ignimbrites in the Campanian Plain, southern Italy

NASA Astrophysics Data System (ADS)

Belkin, Harvey E.; Raia, Federica; Rolandi, Giuseppe; Jackson, John C.; de Vivo, Benedetto

2010-05-01

The Campanian Plain in southern Italy has been volcanically active during the last 600 ka. The largest and best known eruption at 39 ka formed the Campanian Ignimbrite (CI), which has the largest volume (~310 km3) and the greatest areal extent. However, significant, but scattered deposits of older ignimbrites underlie the CI and document a long history of trachytic eruptions. We examined the geochemistry and mineralogy of 11 older ignimbrite strata by optical petrography, electron microprobe, scanning electron microscope, X-ray diffraction, and various whole-rock geochemical techniques. Strata at Durazzano (116.1 ka), Moschiano (184.7 ka), Seiano Valley A (245.9 ka), Seiano Valley B (289.6 ka), Taurano 7 (205.6 and 210.4 ka), Taurano 9 (183.8 ka), and Taurano 14 (157.4 ka) have been previously dated by the 40Ar/39Ar technique (Rolandi et al., 2003, Min. & Pet., 79) on hand-picked sanidine. The older ignimbrites are trachytic, but are highly altered with LOI from 8 to 17 wt%. Whole-rock compositions reflect variable element mobility during weathering; TiO2, Al2O3, Fe-oxide, and CaO tend to be enriched relative to average CI composition, whereas Na2O and K2O are depleted. X-ray diffraction identified major chabazite, kaolinite, and illite-smectite alteration products in some samples. The phenocryst mineralogy in all of the strata is typical for trachyte magma and consists of plagioclase (~An80 to ~An40), potassium feldspar (~Or50 to ~Or80), biotite (TiO2 = ~4.6 wt%, BaO = ~0.70 wt%, F = ~0.65 wt%), diopside (~Ca47Mg48Fe5 to ~Ca48Mg34Fe18), titanomagnetite, and uncommon Ca-amphibole. Relatively immobile trace elements Zr, Hf, Nb, and Th display similar abundance, linear trends, and ratios as those measured in the Campanian Ignimbrite: Th/Hf = ~4, Zr/Hf = ~50, and Zr/Nb = ~6. The similarity of trace element systematics and phenocryst mineralogy among the Campanian Ignimbrite and the older ignimbrites suggests that the magmagenesis processes and parental source have been relatively constant during the long period of trachyte volcanism in the Campanian Plain.

Chemical durability of alkali-borosilicate glasses studied by analytical SEM, IBA, isotopic-tracing and SIMS

NASA Astrophysics Data System (ADS)

Trocellier, P.; Djanarthany, S.; Chêne, J.; Haddi, A.; Brass, A. M.; Poissonnet, S.; Farges, F.

2005-10-01

Simple and complex alkali-borosilicate glasses were submitted to aqueous corrosion at room temperature, 60 and 90 °C in solutions with pH ranging between 0 and 12. Analytical scanning electron microscopy (SEM), ion beam analysis (IBA) techniques, isotopic tracing and secondary ion mass-depth profiling (SIMS) have been used to investigate the variations of the surface composition of glass. In acidic medium, the glass surface is generally covered by a thick hydrated silica layer, mobile elements like Li, Na and B and transition elements (Fe, Zr, Mo, etc.) are strongly depleted. Near pH 7, relative enrichments of aluminium, iron and rare earths are shown together with strong Li, Na and B depletions. In basic medium, the glass surface exhibits relative enrichments of the major part of transition metals (from Cr to U) whereas mobile elements seem to be kept close to their nominal concentration level at the glass surface and Si is severely impoverished. Hydrogen incorporated at the glass surface after leaching is much more immobile in neutral and basic media than in acid medium.

Diogenites: Cumulates from Asteroid 4 Vesta: Insights from Orthopyroxene and Spinel Chemistry

NASA Technical Reports Server (NTRS)

Papike, James J.; Bowman, L. E.; Spilde, M. N.; Fowler, G. W.; Shearer, C. K.

1996-01-01

Cumulate rocks are important planetary lithologies, but they can be difficult to interpret. Important clues to the nature of their parental melts may still be present in the interiors of cumulus phases. However, in some cases, even the cores of the cumulus grains may have been modified by postcrystallization reactions with trapped melt and other cumulus phases. We have previously studied the major-, minor-, and trace-element chemistry of orthopyroxene from a suite of diogenites and concluded that their chemical attributes can best be explained by crystallization from parental melts that were derived from a depleted mantle source that had already experienced eucrite removal. However, we and others have had difficulty explaining the great range in concentration of minor elements (Al, Ti) and trace elements (REE, Y, Zr) if all diogenites were derived from a single magmatic system. Therefore, we have investigated the chemistry of diogenitic spinels to see if they still held clues to the diogenite parental melt compositions. Although spinel is low in abundance in diogenites (<5 vol%) it still may hold clues to the maomatic and metamorphic history of these rocks.

Improving Precision, Maintaining Accuracy, and Reducing Acquisition Time for Trace Elements in EPMA

NASA Astrophysics Data System (ADS)

Donovan, J.; Singer, J.; Armstrong, J. T.

2016-12-01

Trace element precision in electron probe micro analysis (EPMA) is limited by intrinsic random variation in the x-ray continuum. Traditionally we characterize background intensity by measuring on either side of the emission line and interpolating the intensity underneath the peak to obtain the net intensity. Alternatively, we can measure the background intensity at the on-peak spectrometer position using a number of standard materials that do not contain the element of interest. This so-called mean atomic number (MAN) background calibration (Donovan, et al., 2016) uses a set of standard measurements, covering an appropriate range of average atomic number, to iteratively estimate the continuum intensity for the unknown composition (and hence average atomic number). We will demonstrate that, at least for materials with a relatively simple matrix such as SiO2, TiO2, ZrSiO4, etc. where one may obtain a matrix matched standard for use in the so called "blank correction", we can obtain trace element accuracy comparable to traditional off-peak methods, and with improved precision, in about half the time. Donovan, Singer and Armstrong, A New EPMA Method for Fast Trace Element Analysis in Simple Matrices ", American Mineralogist, v101, p1839-1853, 2016 Figure 1. Uranium concentration line profiles from quantitative x-ray maps (20 keV, 100 nA, 5 um beam size and 4000 msec per pixel), for both off-peak and MAN background methods without (a), and with (b), the blank correction applied. We see precision significantly improved compared with traditional off-peak measurements while, in this case, the blank correction provides a small but discernable improvement in accuracy.

Trace Element Zoning and Incipient Metamictization in a Lunar Zircon: Application of Three Microprobe Techniques

NASA Technical Reports Server (NTRS)

Wopenka, Brigitte; Jollife, Bradley L.; Zinner, Ernst; Kremser, Daniel T.

1996-01-01

We have determined major (Si, Zr, Hf), minor (Al, Y, Fe, P), and trace element (Ca, Sc, Ti, Ba, REE, Th, U) concentrations and Raman spectra of a zoned, 200 microns zircon grain in lunar sample 14161,7069, a quartz monzodiorite breccia collected at the Apollo 14 site. Analyses were obtained on a thin section in situ with an ion microprobe, an electron microprobe, and a laser Raman microprobe. The zircon grain is optically zoned in birefringence, a reflection of variable (incomplete) metamictization resulting from zo- nation in U and Th concentrations. Variations in the concentrations of U and Th correlate strongly with those of other high-field-strength trace elements and with changes in Raman spectral parameters. Concentrations of U and Th range from 21 to 55 ppm and 6 to 31 ppm, respectively, and correlate with lower Raman peak intensities, wider Raman peaks, and shifted Si-O peak positions. Concentrations of heavy rare earth elements range over a factor of three to four and correlate with intensities of fluorescence peaks. Correlated variations in trace element concentrations reflect the original magmatic differentiation of the parental melt approx. 4 b.y. ago. Degradation of the zircon structure, as reflected by the observed Raman spectral parameters, has occurred in this sample over a range of alpha-decay event dose from approx. 5.2 x 10(exp 14) to 1.4 x 10(exp 15) decay events per milligram of zircon, as calculated from the U and Th concentrations. This dose is well below the approx. 10(exp 16) events per milligram cumulative dose that causes complete metamictization and indicates that laser Raman microprobe spectroscopy is an analytical technique that is very sensitive to the radiation-induced damage in zircon.

Fluid-mediated mass transfer from a paleosubduction channel to its mantle wedge: Evidence from jadeitite and related rocks from the Guatemala Suture Zone

NASA Astrophysics Data System (ADS)

Harlow, George E.; Flores, Kennet E.; Marschall, Horst R.

2016-08-01

Jadeitites in serpentinite mélanges are the product of crystallization from and/or metasomatism by aqueous fluids that transfer components from and within a subduction channel-the slab-mantle interaction volume-into discrete rock units, most commonly found within the serpentinized or serpentinizing portion of the channel or the overlying mantle rocks at high pressure (1 to > 2 GPa). Two serpentinite mélanges on either side of the Motagua fault system (MFS) of the Guatemala Suture Zone contain evidence of this process. Whole rock compositional analyses are reported here from 86 samples including jadeitites and the related rocks: omphacitites, albitites and mica rocks. The predominance of a single phase in most of these rocks is reflected in the major element compositions and aspects of the trace elements, such as REE abundances tracking Ca in clinopyroxene. Relative to N-MORB all samples show relative enrichments in the high field strength elements (HFSE) Hf, Zr, U, Th, and the LILE Ba and Cs, contrasted by depletions in K and in some cases Pb or Sr. Most jadeitites are also depleted in the highly compatible elements Cr, Sc and Ni despite their occurrence in serpentinite mélange; however, some omphacitite samples show the opposite. Trace elements in these jadeitite samples show a strong similarity with GLOSS (globally subducted oceanic sediment) and other terrigenous sediments in terms of their trace-element patterns, but are offset to lower abundances. Jadeitites thus incorporate a strong trace-element signature derived from sediments mixed with that from fluid derived from altered oceanic crust. Enrichment in the HFSE argues for mobility of these elements in aqueous fluids at high P/T conditions in the subduction channel and a remarkable lack of fractionation that might otherwise be expected from dissolution and fluid transport.

Dust is the dominant source of "heavy metals" to peat moss (Sphagnum fuscum) in the bogs of the Athabasca Bituminous Sands region of northern Alberta.

PubMed

Shotyk, William; Bicalho, Beatriz; Cuss, Chad W; Duke, M John M; Noernberg, Tommy; Pelletier, Rick; Steinnes, Eiliv; Zaccone, Claudio

2016-01-01

Sphagnum fuscum was collected from twenty-five ombrotrophic (rain-fed) peat bogs surrounding open pit mines and upgrading facilities of Athabasca Bituminous Sands (ABS) in northern Alberta (AB) in order to assess the extent of atmospheric contamination by trace elements. As a control, this moss species was also collected at a bog near Utikuma (UTK) in an undeveloped part of AB and 264km SW of the ABS region. For comparison, this moss was also collected in central AB, in the vicinity of the City of Edmonton which is approximately 500km to the south of the ABS region, from the Wagner Wetland which is 22km W of the City, from Seba Beach (ca. 90km W) and from Elk Island National Park (ca. 45km E). All of the moss samples were digested and trace elements concentrations determined using ICP-SMS at a commercial laboratory, with selected samples also analyzed using instrumental neutron activation analysis at the University of Alberta. The mosses from the ABS region yielded lower concentrations of Ag, As, Bi, Cd, Cu, Pb, Sb, Tl, and Zn compared to the moss from the Edmonton area. Concentrations of Ni and Mo in the mosses were comparable in these two regions, but V was more abundant in the ABS samples. Compared with the surface vegetation of eight peat cores collected in recent years from British Columbia, Ontario, Quebec and New Brunswick, the mean concentrations of Ag, As, Bi, Cd, Cu, Mo, Ni, Pb, Sb, Tl and Zn in the mosses from the ABS region are generally much lower. In fact, the concentrations of these trace elements in the samples from the ABS region are comparable to the corresponding values in forest moss from remote regions of central and northern Norway. Lithophile element concentrations (Ba, Be, Ga, Ge, Li, Sc, Th, Ti, Zr) explain most of the variation in trace metal concentrations in the moss samples. The mean concentrations of Th and Zr are greatest in the moss samples from the ABS region, reflecting dust inputs to the bogs from open pit mines, aggregate quarries, and gravel roads. Linear regressions of V, Ni, and Mo (elements enriched in bitumen) versus Sc (a conservative, lithophile element) show excellent correlations in the mosses from the ABS region, but this is true also of Ag, Pb, Sb and Tl: thus, most of the variation in the trace metal concentrations can be explained simply by the abundance of dust particles on the plants of this region. Unlike the moss samples from the ABS region and from UTK where Pb/Sc ratios resemble those of crustal rocks, the moss samples from the other regions studied yielded much greater Pb/Sc ratios implying significant anthropogenic Pb contributions at these other sites. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reduced sediment melting at 7.5-12 GPa: phase relations, geochemical signals and diamond nucleation

NASA Astrophysics Data System (ADS)

Brey, G. P.; Girnis, A. V.; Bulatov, V. K.; Höfer, H. E.; Gerdes, A.; Woodland, A. B.

2015-08-01

Melting of carbonated sediment in the presence of graphite or diamond was experimentally investigated at 7.5-12 GPa and 800-1600 °C in a multianvil apparatus. Two starting materials similar to GLOSS of Plank and Langmuir (Chem Geol 145:325-394, 1998) were prepared from oxides, carbonates, hydroxides and graphite. One mixture (Na-gloss) was identical in major element composition to GLOSS, and the other was poorer in Na and richer in K (K-gloss). Both starting mixtures contained ~6 wt% CO2 and 7 wt% H2O and were doped at a ~100 ppm level with a number of trace elements, including REE, LILE and HFSE. The near-solidus mineral assemblage contained a silica polymorph (coesite or stishovite), garnet, kyanite, clinopyroxene, carbonates (aragonite and magnesite-siderite solid solution), zircon, rutile, bearthite and hydrous phases (phengite and lawsonite at <9 GPa and the hydrous aluminosilicates topaz-OH and phase egg at >10 GPa). Hydrous phases disappear at ~900 °C, and carbonates persist up to 1000-1100 °C. At temperatures >1200 °C, the mineral assemblage consists of coesite or stishovite, kyanite and garnet. Clinopyroxene stability depends strongly on the Na content in the starting mixture; it remains in the Na-gloss composition up to 1600 °C at 12 GPa, but was not observed in K-gloss experiments above 1200 °C. The composition of melt or fluid changes gradually with increasing temperature from hydrous carbonate-rich (<10 wt% SiO2) at 800-1000 °C to volatile-rich silicate liquids (up to 40 wt% SiO2) at high temperatures. Trace elements were analyzed in melts and crystalline phases by LA ICP MS. The garnet-melt and clinopyroxene-melt partition coefficients are in general consistent with results from the literature for volatile-free systems and silicocarbonate melts derived by melting carbonated peridotites. Most trace elements are strongly incompatible in kyanite and silica polymorphs ( D < 0.01), except for V, Cr and Ni, which are slightly compatible in kyanite ( D > 1). Aragonite and Fe-Mg carbonate have very different REE partition coefficients ( D Mst-Sd/L ~ 0.01 and D Arg/L ~ 1). Nb, Ta, Zr and Hf are strongly incompatible in both carbonates. The bearthite/melt partition coefficients are very high for LREE (>10) and decrease to ~1 for HREE. All HFSE are strongly incompatible in bearthite. In contrast, Ta, Nb, Zr and Hf are moderately to strongly compatible in ZrSiO4 and TiO2 phases. Based on the obtained partition coefficients, the composition of a mobile phase derived by sediment melting in deep subduction zones was calculated. This phase is strongly enriched in incompatible elements and displays a pronounced negative Ta-Nb anomaly but no Zr-Hf anomaly. Although all experiments were conducted in the diamond stability field, only graphite was observed in low-temperature experiments. Spontaneous diamond nucleation and the complete transformation of graphite to diamond were observed at temperatures above 1200-1300 °C. We speculate that the observed character of graphite-diamond transformation is controlled by relationships between the kinetics of metastable graphite dissolution and diamond nucleation in a hydrous silicocarbonate melt that is oversaturated in C.

Trace element diffusion in minerals: the role of multiple diffusion mechanisms operating simultaneously

NASA Astrophysics Data System (ADS)

Dohmen, R.; Marschall, H.; Wiedenbeck, M.; Polednia, J.; Chakraborty, S.

2016-12-01

Diffusion of trace elements, often with ionic charge that differs from those of ions in the regular structural sites of a mineral, controls a number of important processes in rocks, such as: (i) Closure of radiogenic isotopic systems, (e.g. Pb diffusion in rutile; REE diffusion in garnet); (ii) Closure of trace element thermometers (e.g., Zr in rutile, Mg in plagioclase, Al in olivine); (iii) Closure of element exchange between melt inclusions and host minerals (e.g., H, REE in olivine). In addition, preserved trace element zoning profiles in minerals can be used for diffusion chronometry (e.g. Nb in rutile, Mg in plagioclase). However, experimentally determined diffusion coefficients of these trace elements are in many cases controversial (e.g., REE in olivine: [1] vs. [2]; Mg in plagioclase: [3] vs. [4]). We have carried out experiments to study the diffusion behavior in olivine, rutile, and plagioclase, and are able to show that two mechanisms of diffusion, differing in rates by up to four orders of magnitude, may operate simultaneously in a given crystal. The two mechanisms result in complex diffusion profile shapes. As a general rule, the incorporation of heterovalent substituting elements in relatively high concentrations is necessary to activate two diffusion mechanisms. This behavior is produced by the control of these elements on the point defect chemistry of a mineral - these impurities become a majority point defect when a threshold concentration limit is exceeded. In certain cases, e.g., for Li in olivine, the trace element can also be incorporated in different sites, resulting in interaction of the different species with other point defects (vacancies) during diffusion. Thus, depending on the diffusion couple used in the experiment, the associated concentration gradients within the mineral, and the analytical techniques used to measure the diffusion profile, only one diffusion mechanism may be activated or detected. These studies allow us to explain some of the differing results noted above and such considerations need to be taken into account when modelling diffusion in natural systems. [1] Cherniak 2010, Am Mineral 95:362-368; [2] Spandler and O'Neill 2010, Contrib Mineral Petrol 159:791-818; [3] Faak et al. 2013 Geochim Cosmochim Acta 123:195-217; [4] Van Orman et al. 2014 Earth Planet Sci Lett 385:79-88

Temporal geochemical evolution of Kilauea Volcano: Comparison of Hilina and Puna Basalt

NASA Astrophysics Data System (ADS)

Chen, C.-Y.; Frey, F. A.; Rhodes, J. M.; Eastern, R. M.

Temporal geochcmical variations in Hawaiian shield-building lavas provide important constraints on the origin and evolution of these lavas. We determined the major and trace element content, and Sr, Nd and Pb isotopic ratios of the oldest subaerially exposed lavas on Kilauea Volcano, i.e., the >25 Ka to perhaps 100 Ka, Hilina Basalt. Except for lower K2O and Rb abundances in Hilina lavas, the compositions of these prehistoric lavas overlap with historical Kilauea lavas. Although the studied Hilina lavas are not highly altered, the lower abundances of K2O and Rb may reflect post-eruptive alteration. Compared with historical Kilauea lavas, Hilina lavas have a similar range in Sr and Nd isotopic ratios, but they range to more radiogenic Pb isotopic ratios. The mantle source of Kilauea lavas is heterogeneous in isotopic ratios and perhaps in abundance ratios of some incompatible elements, but there is no evidence for systematic long-term geochemical variations in the source of Kilauea lavas. None of the prehistoric Kilauea lavas have isotopic characteristics similar to those of subaerial Mauna Loa lavas. Apparently, the sources and ascent paths of lavas forming the adjacent Kilauea and Mauna Loa shields have largely remained distinct during subaerial growth of the Kilauea shield. Compared to lavas from other Hawaiian shields, Kilauea lavas range to relatively high 206Pb/204Pb and low 87Sr/86Sr. These isotopic ratios are correlated with trace element abundance ratios that involve Nb, e.g., Zr/Nb; some Hilina lavas define the upper range in 206Pb/204Pb (˜18.82), and they have low Zr/Nb (˜8). This "Kilauea component" which has isotopic characteristics similar to the FOZO component (e.g., Hauri et al., 1994a] is an intrinsic part of the Hawaiian plume.

Origin of Bermuda's clay-rich Quaternary paleosols and their paleoclimatic significance

USGS Publications Warehouse

Herwitz, S.R.; Muhs, D.R.; Prospero, J.M.; Mahan, S.; Vaughn, B.

1996-01-01

Red clayey paleosols that are chiefly the product of aerosolic dust deposition are interbedded in the Quaternary carbonate formations of the Bermuda oceanic island system. These paleosols provide a basis for reconstructing Quaternary atmospheric circulation patterns in the northwestern Atlantic. Geochemical analyses were performed on representative paleosol samples to identify their parent dust source. Fine-grained fractions were analyzed by energy-dispersive X ray fluorescence to determine trace element (Zr, Y, La, Ti, and Nb) concentrations and to derive geochemical signatures based on immobile element ratios. These ratios were compared with geochemical signatures determined for three possible sources of airborne dust: (1) Great Plains loess, (2) Mississippi River Valley loess, and (3) Saharan dust. The Zr/Y and Zr/La ratios provided the clearest distinction between the hypothesized dust sources. The low ratios in the paleosol B horizons most closely resemble Saharan dust in the <2-??m size class fraction. Contributions from the two North American loessial source areas could not be clearly detected. Thus Bermuda paleosols have a predominantly Saharan aerosolic dust signature. Saharan dust deposition on Bermuda during successive Quaternary glacial periods is consistent with patterns of general circulation models, which indicate that during glacial maxima the northeast summer trade winds were stronger than at present and reached latitudes higher than 30 ?? N despite lower-than-present sea surface temperatures in the North Atlantic.

The peculiar geochemical signatures of São Miguel (Azores) lavas: Metasomatised or recycled mantle sources?

NASA Astrophysics Data System (ADS)

Beier, Christoph; Stracke, Andreas; Haase, Karsten M.

2007-07-01

The island of São Miguel, Azores consists of four large volcanic systems that exhibit a large systematic intra-island Sr-Nd-Pb-Hf isotope and trace element variability. The westernmost Sete Cidades volcano has moderately enriched Sr-Nd-Pb-Hf isotope ratios. In contrast, lavas from the easternmost Nordeste volcano have unusually high Sr and Pb and low Nd and Hf isotope ratios suggesting a long-term evolution with high Rb/Sr, U/Pb, Th/Pb, Th/U and low Sm/Nd and Lu/Hf parent-daughter ratios. They have trace element concentrations similar to those of the HIMU islands, with the exception of notably higher alkali element (Cs, Rb, K, Ba) and Th concentrations. The time-integrated parent-daughter element evolution of both the Sete Cidades and Nordeste source matches the incompatibility sequence commonly observed during mantle melting and consequently suggests that the mantle source enrichment is caused by a basaltic melt, either as a metasomatic agent or as recycled oceanic crust. Our calculations show that a metasomatic model involving a small degree basaltic melt is able to explain the isotopic enrichment but, invariably, produces far too enriched trace element signatures. We therefore favour a simple recycling model. The trace element and isotopic signatures of the Sete Cidades lavas are consistent with the presence of ancient recycled oceanic crust that has experienced some Pb loss during sub-arc alteration. The coherent correlation of the parent-daughter ratios (e.g. Rb/Sr, Th/U, U/Pb) and incompatible element ratios (e.g. Nb/Zr, Ba/Rb, La/Nb) with the isotope ratios in lavas from the entire island suggest that the Sete Cidades and Nordeste source share a similar genetic origin. The more enriched trace element and isotopic variations of Nordeste can be reproduced by recycled oceanic crust in the Nordeste source that contains small amounts of evolved lavas (˜ 1-2%), possibly from a subducted seamount. The rare occurrence of enriched source signatures comparable to Nordeste may be taken as circumstantial evidence that stirring processes in the Earth's mantle are not able to homogenise material within the size of seamounts over timescales of mantle recycling.

Partitioning of Nb, Mo, Ba, Ce, Pb, Th and U between immiscible carbonate and silicate liquids: Evaluating the effects of P2O5,F, and carbonate composition

NASA Technical Reports Server (NTRS)

Jones, J. H.; Walker, D.

1993-01-01

Previously we have reported carbonate liq./silicate liq. partition coefficients (D) for a standard suite of trace elements (Nb, Mo, Ba, Ce, Pb, Th, and U) and Ra and Pa as well. In brief, we have found that immiscible liquid partitioning is a strong function of temperature. As the critical temperature of the carbonate-silicate solvus is approached, all partition coefficients approach unity. Additionally, for the overwhelming majority of the partitioning elements, InD is a linear function of 'ionic field strength,' z/r, where z is the charge of the partitioned cation and r is its ionic radius.

The geochemistry and petrogenesis of an ophiolitic sequence from Pindos, Greece

NASA Astrophysics Data System (ADS)

Capedri, S.; Venturelli, G.; Bocchi, G.; Dostal, J.; Garuti, G.; Rossi, A.

1980-06-01

The ophiolites of Northern Pindos have been studied in a section close to the village of Perivoli (Grevena District). The section comprises cumulus rocks ranging from ultramafics to gabbros, overlain by dolerites (non-cumulus microgabbro) capped by thick frequently pillowed lava flows. The sequence is cut by basaltic dykes. While the cumulus rocks and the dolerites are mostly fresh, the lavas and dykes are strongly transformed. Major and trace element (Ni, Cr, Sc, Y, Zr, Nb, Sr, Ba, Zn, Cu, V, Li) data are presented for selected samples from the sequence. For some elements, the volcanic/subvolcanic rocks (flows, dykes, dolerites) exhibit wide chemical characteristics which are considered to mainly reflect variations within the parent magmas. Some lavas appear to be closely comparable with the present-day ocean-floor basalts, while other flows and most of the dykes are strongly depleted in some “incompatible” elements and are similar to some rocks from immature island arcs. The dolerites have transitional chemical features. The Pindos lavas differ from Western Mediterranean ophiolites in that the former have lower Ti,P,Zr,Y, higher Fe tot. and normally higher Ti/Zr ratio. The volcanic/subvolcanic rocks from Pindos have been derived from separate magmas. Some lavas were possibly produced by variable partial melting of an already depleted mantle source, while the lavas exhibiting ocean-floor affinity were probably generated by partial melting of a less depleted source. The wide chemical variations of the Pindos lavas cannot be easily explained by an ocean-ridge system. An “island arc-marginal basin system” could better account for the observed chemical features.

Two modes of orogenic collapse of the Pamir plateau recorded by titanite

NASA Astrophysics Data System (ADS)

Stearns, M. A.; Hacker, B. R.; Ratschbacher, L.; Rutte, D.; Kylander-Clark, A. R.

2013-12-01

Processes that operate in the mid- to lower crust during and following continent-continent collision are important for understanding how orogenic plateaux transition from thickening to collapse. In the central and southern Pamir, mid- to lower crustal rocks crop out in two belts of extensional domes. The central Pamir domes were exhumed by symmetrical N-S extension. In contrast, the southern Pamir domes were exhumed by asymmetrical top to the south (NNW-SSE) extension via a rolling-hinge detachment. To investigate the high-temperature exhumation history, titanites were dated using LASS (laser ablation split stream-ICP-MS). A multi-collector ICP was used to collect U-Pb isotopic ratios and a single collector ICP-MS was used to measure trace-element abundances. The data indicate that the central Pamir domes began exhumation synchronously at ~17 Ma. Titanite from the southern Pamir record two periods of protracted (re)crystallization: older metamorphic dates ranging from ~35-18 Ma and younger igneous and metamorphic dates from ~15-7 Ma. Samples with single populations of titanite dates are present throughout both groups. Samples with more-complex date populations typically have distinct trace-element (e.g., Sr, Y, Zr, and Nb) groups that can be used to distinguish different date populations (e.g., older dates may have higher Zr and younger dates lower Zr). The distinct early exhumation histories of the north and south Pamir require either a diachronous single process or two semi-independent processes. The N to S sequence of exhumation, ranges of dates, and overall extension directions may be related to two important plate-tectonic events inferred from seismic data: 1) breakoff of the northward subducting Indian slab around ~20 Ma, and 2) southward subduction and northwestward rollback of the Asian lithosphere between ~15-10 Ma based on geodetic convergence rates and Benioff zone length. We interpret these two lithospheric-detachment events to have driven the exhumation in the Pamir by changing the gravitational potential energy and boundary forces of the plateau.

Titanite chronology, thermometry, and speedometry of ultrahigh-temperature (UHT) calc-silicates from south Madagascar: U-Pb dates, Zr temperatures, and lengthscales of trace-element diffusion

NASA Astrophysics Data System (ADS)

Holder, R. M.; Hacker, B. R.

2017-12-01

Calc-silicate rocks are often overlooked as sources of pressure-temperature-time data in granulite-UHT metamorphic terranes due to the strong dependence of calc-silicate mineral assemblages on complex fluid compositions and a lack of thermodynamic data on common high-temperature calc-silicate minerals such as scapolite. In the Ediacaran-Cambrian UHT rocks of southern Madagascar, clinopyroxene-scapolite-feldspar-quartz-zircon-titanite calc-silicate rocks are wide-spread. U-Pb dates of 540-520 Ma from unaltered portions of titanite correspond to cooling of the rocks through upper-amphibolite facies and indicate UHT metamorphism occurred before 540 Ma. Zr concentrations in these domains preserve growth temperatures of 900-950 °C, consistent with peak temperatures calculated by pseudosection modeling of nearby osumilite-bearing gneisses. Younger U-Pb dates (510-490 Ma) correspond to fluid-mediated Pb loss from titanite grains, which occurred below their diffusive Pb-closure temperature, along fractures. The extent of fluid alteration is seen clearly in back-scattered electron images and Zr-, Al-, Fe-, Ce-, and Nb-concentration maps. Laser-ablation depth profiling of idioblastic titanite grains shows preserved Pb diffusion profiles at grain rims, but there is no evidence for Zr diffusion, indicating that it was effectively immobile even at UHT.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cebi, F.H.; Korkmaz, S.; Akcay, M.

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 element contents. The vertical distribution of trace elements in individual coal seams is also rather consistent. The B contents of coalsmore » 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.« less

Orthopyroxene as a recorder of primitive achondrite petrogenesis: Major-, minor-, and trace-element systematics of orthopyroxene in Lodran. [Abstract only

NASA Technical Reports Server (NTRS)

Papike, J. J.; Spilde, M. N.; Fowler, G. W.; Shearer, C. K.

1994-01-01

Considerable attention has been paid recently to the primitive achondrites because they may form a link between chondrites and more differentiated achondrite meteorites. A recent paper by Miyamoto and Takeda addresses the thermal history of lodranites Yamato 74357 and MAC 88177 as inferred from chemical zoning of pyroxene and olivine determined by electron microprobe analyses. Their results suggested that interstitial melt was present and then extracted. We have taken the analysis of Lodran-type meteorites one step further by incorporating the techniques of Electromagnetic Pulse/Wavelength Dispersive Spectroscopy (EMP/WDS) compositional imaging and scanning ion mass spectroscopy (SIMS) analysis. Orthopyroxene in Lodran is strongly zoned in CaO, Al2O3, TiO2, and Cr2O3 within the last 10-30 microns from the grain boundaries. The rims are reversely zoned in Mg-Fe, exhibiting Mg enrichment, and compositions change from a fairly uniform Wo3En94 within the grains to Wo1En96 at the rims. CaO drops from 1.6 to 0.6 wt% and Al2O3, TiO2, and Cr2O3 exhibit similar depletions. MnO is fairly uniform throughout the grains at around 0.5 wt%. Olivine is also reversely zoned with respect to not only grain boundaries but also to fractures within the grains, giving many olivine grains a complex, patchy zoning pattern. Some of the core-rim trace-element systematics for orthopyroxene are illustrated. Because of the rather narrow zoned rims in Lodran orthopyroxene and the low trace-element abundances, it is difficult to clearly resolve the trace-element systematics. Nevertheless it is evident that the cores are enriched in the incompatible trace elements Ce, Nd, Dy, Er, Yb, Y, and Zr relative to the rims.

Source origin of trace elements in PM from regional background, urban and industrial sites of Spain

NASA Astrophysics Data System (ADS)

Querol, X.; Viana, M.; Alastuey, A.; Amato, F.; Moreno, T.; Castillo, S.; Pey, J.; de la Rosa, J.; Sánchez de la Campa, A.; Artíñano, B.; Salvador, P.; García Dos Santos, S.; Fernández-Patier, R.; Moreno-Grau, S.; Negral, L.; Minguillón, M. C.; Monfort, E.; Gil, J. I.; Inza, A.; Ortega, L. A.; Santamaría, J. M.; Zabalza, J.

Despite their significant role in source apportionment analysis, studies dedicated to the identification of tracer elements of emission sources of atmospheric particulate matter based on air quality data are relatively scarce. The studies describing tracer elements of specific sources currently available in the literature mostly focus on emissions from traffic or large-scale combustion processes (e.g. power plants), but not on specific industrial processes. Furthermore, marker elements are not usually determined at receptor sites, but during emission. In our study, trace element concentrations in PM 10 and PM 2.5 were determined at 33 monitoring stations in Spain throughout the period 1995-2006. Industrial emissions from different forms of metallurgy (steel, stainless steel, copper, zinc), ceramic and petrochemical industries were evaluated. Results obtained at sites with no significant industrial development allowed us to define usual concentration ranges for a number of trace elements in rural and urban background environments. At industrial and traffic hotspots, average trace metal concentrations were highest, exceeding rural background levels by even one order of magnitude in the cases of Cr, Mn, Cu, Zn, As, Sn, W, V, Ni, Cs and Pb. Steel production emissions were linked to high levels of Cr, Mn, Ni, Zn, Mo, Cd, Se and Sn (and probably Pb). Copper metallurgy areas showed high levels of As, Bi, Ga and Cu. Zinc metallurgy was characterised by high levels of Zn and Cd. Glazed ceramic production areas were linked to high levels of Zn, As, Se, Zr, Cs, Tl, Li, Co and Pb. High levels of Ni and V (in association) were tracers of petrochemical plants and/or fuel-oil combustion. At one site under the influence of heavy vessel traffic these elements could be considered tracers (although not exclusively) of shipping emissions. Levels of Zn-Ba and Cu-Sb were relatively high in urban areas when compared with industrialised regions due to tyre and brake abrasion, respectively.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dupre, B.; Rousseau, D.; Gaillardet, J.

The Congo river Basin is the second largest drainage basin in the world, after the Amazon. The materials carried by its main rivers provide the opportunity to study the products of denudation of a large fraction of the upper continental crust of the African continent. This paper presents the chemical composition of the different phases carried in the Congo rivers and is followed by a companion paper, devoted to the modelling of major and trace elements. The Congo river between Bangui and Brazzaville as well as its main tributaries, including a few organic-rich rivers, also called Black Rivers, were sampledmore » during the 1989 high water stage. The three main phases (suspended load, dissolved load, and bedload) were analysed for twenty-five major and trace elements. Concentrations normalized to the upper continental crust show that in each river, suspended sediments and dissolved load are chemical complements for the most soluble elements (Ca, Na, Sr, K, Ba, Rb, and U). While these elements are enriched in the dissolved loads, they are considerably depleted in the corresponding suspended sediments. This is consistent with their high mobility during weathering. Another type of complementarity is observed for Zr and Hf between suspended sediments and bedload, related to the differential velocity of suspended sediments and zircons which are concentrated in bedloads. Compared to other rivers, absolute dissolved concentrations of Ca, Na, Sr, K, Ba, Rb, and U are remarkably low. Surprisingly, high dissolved concentrations are found in the Congo waters for other trace elements (e.g., REEs), especially in the Black rivers. On a world scale, these concentrations are among the highest measured in rivers and are shown to be pH dependent for a number of dissolved trace elements. The dissolved loads are systematically normalized to the suspended loads for each river, in order to remove the variations of the element abundances owing to source rock variations.« less

Variation of Nb-Ta, Zr-Hf, Th-U and K-Cs in two diabase-granophyre suites

USGS Publications Warehouse

Gottfried, D.; Greenland, L.P.; Campbell, E.Y.

1968-01-01

Concentrations of Nb, Ta, Zr, Hf, Th, U and Cs have been determined in samples of igneous rocks representing the diabase-granophyre suites from Dillsburg, Pennsylvania, and Great Lake, Tasmania. Niobium and tantalum have a three to fourfold increase with differentiation in each of the suites. The chilled margin of the Great Lake intrusion contains half the niobium and tantalum content (5.3 ppm and 0.4 ppm, respectively) of the chilled basalt from Dillsburg (10 ppm and 0.9 ppm, respectively). The twofold difference between the suites is correlated with differences in their titanium content. The average Nb Ta ratios for each suite are similar: 13.5 for the Great Lake suite, and 14.4 for the Dillsburg suite. The zirconium content of the two suites is essentially the same and increases from 50 to 60 ppm in the chilled margins to 240-300 ppm in the granophyres. Hafnium is low in the early formed rocks (0.5 -1.5 ppm and achieves a maximum in the granophyres (5-8 ppm). The Zr Hfratio decreases from 68 to 33 with progressive differentiation. In the Dillsburg suite thorium and uranium increase from 2.6 ppm and 0.6 ppm, respectively, in the chilled samples to 11.8 ppm and 3.1 ppm in the granophyres. The chilled margin of the Great Lake suite contains 3.2 ppm thorium and 9.8 ppm uranium; the granophyre contains 11.2 ppm thorium and 2.8 ppm uranium. The average Th U ratios of the Dillsburg and Great Lake suites are nearly the same-4.1 and 4.4, respectively. Within each suite the Th U ratio remains quite constant. Cesium and the K Cs ratio do not vary systematically in the Dillsburg suite possibly because of redistribution or loss of cesium by complex geologic processes. Except for the chilled margin of the Great Lake suite, the variation of Cs and the K Cs ratio are in accord with theoretical considerations. Cesium increases from about 0.6 ppm in the lower zone to 3.5 ppm in the granophyre; the K Cs ratio varies from 10 ?? 103 in the lower zone to 6 ?? 103 in the granophyre. A comparison of the abundance of some of these elements is made with those reported on oceanic tholeiites from the Atlantic and Pacific oceans. Trace elements with large ionic radii (Th, U, Cs) are present in significantly greater concentrations in the two continental tholeiitic series than in the oceanic tholeiites. However, this does not seem to be true for lithophilic elements of smaller ionic radii (Zr and Nb). These trace element distribution patterns, when considered with other minor element and isotopic studies, indicate that 1. (1) crustal contamination does not entirely account for differences between continental and oceanic tholeiites, and 2. (2) the oceanic tholeiites do not necessarily delimit the geochemical characteristics of the mantle. ?? 1968.

Major and trace elements in organically or conventionally produced milk.

PubMed

Hermansen, John E; Badsberg, Jens H; Kristensen, Troels; Gundersen, Vagn

2005-08-01

A total of 480 samples of milk from 10 organically and 10 conventionally producing dairy farms in Denmark and covering 8 sampling periods over 1 year (triplicate samplings) were analysed for 45 trace elements and 6 major elements by high-resolution inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry. Sampling, sample preparation, and analysis of the samples were performed under carefully controlled contamination-free conditions. The dairy cattle breeds were Danish-Holstein or Jersey. Sources of variance were quantified, and differences between production systems and breeds were tested. The major source of variation for most elements was week of sampling. Concentrations of Al, Cu, Fe, Mo, Rb, Se, and Zn were within published ranges. Concentrations of As, Cd, Cr, Mn and Pb were lower, and concentrations of Co and Sr were higher than published ranges. Compared with Holsteins, Jerseys produced milk with higher concentrations of Ba, Ca, Cu, Fe, Mg, Mn, Mo, P, Rh, and Zn and with a lower concentration of Bi. The organically produced milk, compared with conventionally produced milk, contained a significantly higher concentration of Mo (48 v. 37 ng/g) and a lower concentration of Ba (43 v. 62 ng/g), Eu (4 v. 7 ng/g), Mn (16 v. 20 ng/g) and Zn (4400 v. 5150 ng/g respectively). The investigation yielded typical concentrations for the following trace elements in milk, for which no or very few data are available: Ba, Bi, Ce, Cs, Eu, Ga, Gd, In, La, Nb, Nd, Pd, Pr, Rh, Sb, Sm, Tb, Te, Th, Ti, Tl, U, V, Y, and Zr.

Petrography and trace element signatures in silicates and Fe-Ti-oxides from the Lanjiahuoshan deposit, Panzhihua layered intrusion, Southwest China

NASA Astrophysics Data System (ADS)

Gao, Wenyuan; Ciobanu, Cristiana L.; Cook, Nigel J.; Huang, Fei; Meng, Lin; Gao, Shang

2017-12-01

Permian mafic-ultramafic layered intrusions in the central part of the Emeishan Large Igneous Province (ELIP), Southwestern China, host Fe-Ti-V-oxide ores that have features which distinguish them from other large layered intrusion-hosted deposits. The origin of these ores is highly debated. Careful petrographic examination, whole rock analysis, electron probe microanalysis, and measurement and mapping of trace element concentrations by laser ablation inductively coupled plasma mass spectrometry in all major and minor minerals (clinopyroxene, plagioclase, olivine, amphibole, titanomagnetite, ilmenite, pleonaste and pyrrhotite) has been undertaken on samples from the Lanjiahuoshan deposit, representing the Middle, Lower and Marginal Zone of the Panzhihua intrusion. Features are documented that impact on interpretation of intrusion petrology and with implications for genesis of the Fe-Ti-V-oxide ores. Firstly, there is evidence, as symplectites between clinopyroxene and plagioclase, for introduction of complex secondary melts. Secondly, reaction between a late hydrothermal fluid and clinopyroxene is recognized, which has led to formation of hydrated minerals (pargasite, phlogopite), as well as a potassium metasomatic event, postdating intrusion solidification, which led to formation of K-feldspar. Lastly, partitioning of trace elements between titanomagnetite and silicates needs to consider scavenging of metals by ilmenite (Mn, Sc, Zr, Nb, Sn, Hf and Ta) and sulfides, as well as the marked partitioning of Co, Ni, Zn, Ga, As and Sb into spinels exsolved from titanomagnetite. The role of these less abundant phases may have been understated in previous studies, highlighting the importance of petrographic examination of complex silicate-oxide-sulfide assemblages, as well as the need for a holistic approach to trace element analysis, acknowledging all minerals within the assemblage.

Trace Element Study of MORB Glasses from 14¡ã-16¡ãN along Mid-Atlantic Ridge by LA-ICP- MS

NASA Astrophysics Data System (ADS)

Barzoi, C. A.; Casey, J. F.; Gao, Y.; Lapen, T.

2007-12-01

A comparison of 20 MORB glasses from 14°-16° N along the Mid-Atlantic Ridge using both solution-based and in situ laser ablation-based ICP-MS trace element analyses on the same samples was conducted. Li, Be, Sc, Ti, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Ba, La, Ce, Pr, Nd, Sm, Eu, Tb, Gd, Dy, Ho, Er, Tm, Yb,Lu, Hf, Ta, Pb, Th, and U were analyzed using the Varian 810 quadrupole ICP-MS. The instrument features a 90 degree ion mirror and low noise double-off-axis quadrupole that allows high sensitivity and low backgrounds. Precision in term of relative standard deviation (RSD) of the measurements for both methods based on repeated analyses of USGS BIR-1G and BHVO-2G glass standards and Max Planck KL-2G glass standard is within 5 % for all trace elements with the exception of Pb, which averaged 12 %. Measured trace element abundances are within 2% of recommended standard values using both solution and laser ablation methods. Comparison between the analyte concentrations obtained by solution-based ICP-MS and in situ microanalysis by laser ablation reveals little systematic differences in abundances(<5% for all elements). The two-method correlation and strong repeatability of the results indicate that rapid in situ trace element analysis by laser ablation ICP-MS is likely to become a preferred method of trace element analysis for MORB glasses. Our geochemical results and previous studies of MORB glasses in the region of the MAR between 14°-16°N show that basalts are characterized isotopic and incompatible element enrichment.The nature of the enrichment has been the topic of significant discussion and speculation because a specific mantle plume is not well defined in the region. Likewise the magma supply is probably small in the region as the magmatic crust is interpreted to be very thin in most of the area studied. Integrated studies of major element, trace element, and isotopic variations among basalts, gabbroic rocks and igneous and residual ultramafic rocks in the region indicate that 1) the enriched basalts have positive Ta-Nb anomalies, enriched relative to U, Th, and La 2) basalts have relatively high SiO2 abundances compared to the global average, 3) basalts show a HIMU isotopic signature, and 4) bulk major element abundances and mineral chemistry in mantle rocks indicate that they are among the most depleted,although variably refertilized, residual mantle assemblages sampled to date along MORs.We suggest that much of the regional variation in major and trace element data, as well as isotopic data and the unusual regional geology (multiple core complexes) can be explained by melting of a sub-axial mantle that contains two end members, one highly depleted and the other enriched. These components appear to involve ancient recycled ocean crust and lithospheric mantle.

Neutron- and photon-activation detection limits in breast milk analysis for prospective dose evaluation of the suckling infant.

PubMed

Tsipenyuk, Yu M; Firsov, V I; Cantone, M C

2009-01-01

Complex situations related to the environment, as in the regions affected by the Chernobyl accident and regions in which nuclear weapons testing were undertaken, as in Semipalatinsk, could be reflected in the trace element content in mothers' milk. The evaluation of fractional transfer to milk of ingested or inhaled activity and of the corresponding dose coefficients for the infant, following a mothers' radioactive intake, can take advantage from wide-ranging studies of elemental and radionuclide contents in mothers' milk. In this work the possibility to determine elements, such as Ru, Zr, Nb, Te, Ce, Th, U, in milk powder has been investigated. Although results from elemental analyses of breast milk are to be found in the literature, the determination of the identified elements has attracted poor attention since they are not considered essential elements from a biological point of view. Nevertheless, in the case of radioactive releases to the environment, such data could be of interest in evaluation of dose to the breast-fed infant.

Geomorphological assessment of sediment contamination in an urban stream system

USGS Publications Warehouse

Rhoads, B.L.; Cahill, R.A.

1999-01-01

Little is known about the influence of fluvial-geomorphological features on the dispersal of sediment-related contaminants in urban drainage systems. This study investigates the relation between reach-scale geomorphological conditions and network-scale patterns of trace-element concentrations in a partially urbanized stream system in East-Central Illinois, USA Robust statistical analysis of bulk sediment samples reveals levels of Cr, Cu, Pb, Ni, and Zn exceed contamination thresholds in the portion of the watershed in close proximity to potential sources of pollution-in this case storm-sewer outfalls. Although trace-element concentrations decrease rapidly downstream from these sources, substantial local variability in metal levels exists within contaminated reaches. This local variability is related to reach-scale variation in fluvial-geomorphic conditions, which in turn produces variation in the degree of sorting and organic-matter content of bed material. Metal concentrations at contaminated sites also exhibit considerable variability over time. Analytical tests on specific size fractions of material collected at a highly contaminated site indicate that Cr and Ni are concentrated in the 0.063 to 0.250 mm fraction of the sediment. This fraction also has elevated concentration of Zr. SEM analysis shows that the fine sand fraction contains shards of stainless steel within a matrix of zircon sand, an industrial material associated with a nearby alloy casting operation. Samples of suspended load and bedload at the contaminated site also have elevated amounts of trace metals, but concentrations of Ni and Cr in the bedload are less than concentrations in the bed material, suggesting that these trace elements are relatively immobile. Off the other hand, amounts of CU and Zn in the bedload exceed concentrations in the bed material, implying that these trace metals are preferentially mobilized during transport events.

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

PubMed

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

2013-10-01

The colloidal distribution and size fractionation of organic carbon (OC), major elements and trace elements (TE) were studied in a seasonally stratified, organic-rich boreal lake, Lake Svyatoe, located in the European subarctic zone (NW Russia, Arkhangelsk region). This study took place over the course of 4 years in both winter and summer periods using an in situ dialysis technique (1 kDa, 10 kDa and 50 kDa) and traditional frontal filtration and ultrafiltration (5, 0.22 and 0.025 μm). We observed a systematic difference in dissolved elements and colloidal fractions between summer and winter periods with the highest proportion of organic and organo-ferric colloids (1 kDa-0.22 μm) observed during winter periods. The anomalously hot summer of 2010 in European Russia produced surface water temperatures of approximately 30°C, which were 10° above the usual summer temperatures and brought about crucial changes in element speciation and size fractionation. In August 2010, the concentration of dissolved organic carbon (DOC) decreased by more than 30% compared to normal period, while the relative proportion of organic colloids decreased from 70-80% to only 20-30% over the full depth of the water column. Similarly, the proportion of colloidal Fe decreased from 90-98% in most summers and winters to approximately 60-70% in August 2010. During this hot summer, measurable and significant (>30% compared to other periods) decreases in the colloidal fractions of Ca, Mg, Sr, Ba, Al, Ti, Ni, As, V, Co, Y, all rare earth elements (REEs), Zr, Hf, Th and U were also observed. In addition, dissolved (<0.22 μm) TE concentrations decreased by a factor of 2 to 6 compared to previously investigated periods. The three processes most likely responsible for such a crucial change in element biogeochemistry with elevated water temperature are 1) massive phytoplankton bloom, 2) enhanced mineralization (respiration) of allochthonous dissolved organic matter by heterotrophic aerobic bacterioplankton and 3) photo-degradation of DOM and photo-chemical liberation of organic-bound TE. While the first process may have caused significant decreases in the total dissolved concentration of micronutrients (a factor of 2 to 5 for Cr, Mn, Fe, Ni, Cu, Zn and Cd and a factor of >100 for Co), the second and third factors could have brought about the decrease of allochthonous DOC concentration as well as the concentration and proportion of organic and organo-mineral colloidal forms of non-essential low-soluble trace elements present in the form of organic colloids (Al, Y, Ti, Zr, Hf, Th, Pb, all REEs). It can be hypothesized that climate warming in high latitudes capable of significantly raising surface water temperatures will produce a decrease in the colloidal fraction of most trace elements and, as a result, an increase in the most labile low molecular weight LMW(<1 kDa) fraction. Copyright © 2013 Elsevier B.V. All rights reserved.

Ti-rich komatiites from northern Norway

NASA Astrophysics Data System (ADS)

Barnes, Sarah-Jane; Often, Morten

1990-06-01

Komatiites of the Karasjok Greenstone Belt, northern Norway, show two unusual features: they have certain compositional differences compared with other komatiites, and they are largely volcaniclastic in origin. Their geological setting suggests that the komatiites were crupted into shallow water, thus permitting phreatomagmatic eruption, in a small ocean basin that opened in the Baltic Shield. The major oxides (except for TiO2), the trace elements Y, Sc, V, heavy rare earth elements (HREE), Cr, Co, Ni and the platinum group elements (PGE) cover similar ranges to those observed in other komatiites, but TiO2, Sm, Zr and Hf (Ti-associated elements, TAE) are enriched compared with abundances commonly reported for komatiites. Thus, the Karasjok komatiites have interelement ratios 2 to 3 times greater than chondritic between the TAE and the HREE, PGE, Sc, V, Y, Al (HRE-associated elements, HAE). The light rare earth elements (LREE), Ta and Th are enriched in some samples relative to Ti, Sm, Zr, and Hf, but are depleted in others. One group of rocks that is similar to the Karasjok komatiites both in terms of geological setting and geochemistry is the Baffin Bay picrites. The reason for the high concentrations of TAE in the Karasjok komatiites could be that they formed at lower degrees of partial melting than most komatiites. The greater-than-chondritic TAE/HAE ratios indicate that garnet was a residual phase during their formation, requiring that the melt formed at a pressure greater than 40 kb. A model involving decompression melting of a mantle plume rising in a rifting environment, can explain the main features of the Karasjok komatiites.

Insights into the evolution of an alkaline magmatic system: An in situ trace element study of clinopyroxenes from the Ditrău Alkaline Massif, Romania

NASA Astrophysics Data System (ADS)

Batki, Anikó; Pál-Molnár, Elemér; Jankovics, M. Éva; Kerr, Andrew C.; Kiss, Balázs; Markl, Gregor; Heincz, Adrián; Harangi, Szabolcs

2018-02-01

Clinopyroxene is a major constituent in most igneous rock types (hornblendite, diorite, syenite, nepheline syenite, camptonite, tinguaite and ijolite) of the Ditrău Alkaline Massif, Eastern Carpathians, Romania. Phenocryst and antecryst populations have been distinguished based on mineral zoning patterns and geochemical characteristics. Major and trace element compositions of clinopyroxenes reflect three dominant pyroxene types including primitive high-Cr Fe-diopside, intermediate Na-diopside-hedenbergite and evolved high-Zr aegirine-augite. Clinopyroxenes record two major magma sources as well as distinct magma evolution trends. The primitive diopside population is derived from an early camptonitic magma related to basanitic parental melts, whilst the intermediate diopside-hedenbergite crystals represent a Na-, Nb- and Zr-rich magma source recognised for the first time in the Ditrău magmatic system. This magma fractionated towards ijolitic and later phonolitic compositions. Field observations, petrography and clinopyroxene-melt equilibrium calculations reveal magma recharge and mingling, pyroxene recycling, fractional crystallisation and accumulation. Repeated recharge events of the two principal magmas resulted in multiple interactions between more primitive and more fractionated co-existing magma batches. Magma mingling occurred between mafic and felsic magmas by injection of ijolitic magma into fissures (dykes) containing phonolitic (tinguaite) magma. This study shows that antecryst recycling, also described for the first time in Ditrău, is a significant process during magma recharge and demonstrates that incorporated crystals can crucially affect the host magma composition and so whole-rock chemical data should be interpreted with great care.

Inorganic analyses of Martian surface samples at the Viking landing sites

NASA Technical Reports Server (NTRS)

Clark, B. C.; Castro, A. J.; Rowe, C. D.; Baird, A. K.; Evans, P. H.; Rose, H. J., Jr.; Toulmin, P., III; Keil, K.; Kelliher, W. C.

1976-01-01

Elemental analyses of fines in the Martian regolith at two widely separated landing sites, Chryse Planitia and Utopia Planitia, produced remarkably similar results. At both sites, the uppermost regolith contains abundant Si and Fe, with significant concentrations of Mg, Al, S, Ca, and Ti. The S concentration is one to two orders of magnitude higher, and K (less than 0.25% by weight) is at least 5 times lower than the average for earth's crust. The trace elements Sr, Y, and possibly Zr have been detected at concentrations near or below 100 parts per million. Pebble-sized fragments sampled at Chryse contain more S than the bulk fines and are thought to be pieces of a sulfate-cemented duricrust.

Inorganic analyses of martian surface samples at the viking landing sites.

PubMed

Clark, B C; Baird, A K; Rose, H J; Toulmin, P; Keil, K; Castro, A J; Kelliher, W C; Rowe, C D; Evans, P H

1976-12-11

Elemental analyses of fines in the Martian regolith at two widely separated landing sites, Chryse Planitia and Utopia Planitia, produced remarkably similar results. At both sites, the uppermost regolith contains abundant Si and Fe, with significant concentrations of Mg, Al, S, Ca, and Ti. The S concentration is one to two orders of magnitude higher, and K(<0.25 percent by weight) is at least 5 times lower than the average for the earth's crust. The trace elements Sr, Y, and possibly Zr, have been detected at concentrations near or below 100 parts per million. Pebblesized fragments sampled at Chryse contain more S than the bulk fines, and are thought to be pieces of a sulfate-cemented duricrust.

Refractory inclusions with unusual chemical compositions from the Vigarano carbonaceous chondrite

NASA Technical Reports Server (NTRS)

Sylvester, Paul J.; Grossman, Lawrence; Macpherson, Glenn J.

1992-01-01

Neutron activation was used to test ten inclusions, nine Vigarano and one from Leoville, for major and trace elements. Six Vigarano refractory inclusions have refractory element fractionations that are rare or absent in Allende inclusions. Vig 1623-11 has Th/La and Ir/Mo ratios that are lower than those of any Allende Group I or modified Group I inclusions, and Os/La, Ir/La, and Zr/Hf ratios that are among the lowest in those inclusions. The low Os/La, Ir/La, and Ir/Mo ratios seem to require nonrepresentative sampling of condensate phase in the nebula to a degree that is usual for Allende Group I and modified group I inclusions. The nature and origins of the different inclusions are discussed.

Evolution of the Campanian Ignimbrite Magmatic System II: Trace Element and Th Isotopic Evidence for Open-System Processes

NASA Astrophysics Data System (ADS)

Bohrson, W. A.; Spera, F. J.; Fowler, S.; Belkin, H.; de Vivo, B.

2005-12-01

The Campanian Ignimbrite, a large volume (~200 km3 DRE) trachytic to phonolitic ignimbrite was deposited at ~39.3 ka and represents the largest of a number of highly explosive volcanic events in the region near Naples, Italy. Thermodynamic modeling of the major element evolution using the MELTS algorithm (see companion contribution by Fowler et al.) provides detailed information about the identity of and changes in proportions of solids along the liquid line of descent during isobaric fractional crystallization. We have derived trace element mass balance equations that explicitly accommodate changing mineral-melt bulk distribution coefficients during crystallization and also simultaneously satisfy energy and major element mass conservation. Although major element patterns are reasonably modeled assuming closed system fractional crystallization, modeling of trace elements that represent a range of behaviors (e.g. Zr, Nb, Th, U, Rb, Sm, Sr) yields trends for closed system fractionation that are distinct from those observed. These results suggest open-system processes were also important in the evolution of the Campanian magmatic system. Th isotope data yield an apparent isochron that is ~20 kyr younger than the age of the deposit, and age-corrected Th isotope data indicate that the magma body was an open-system at the time of eruption. Because open-system processes can profoundly change isotopic characteristics of a magma body, these results illustrate that it is critical to understand the contribution that open-system processes make to silicic magma bodies prior to assigning relevance to age or timescale information derived from isotope systematics. Fluid-magma interaction has been proposed as a mechanism to change isotopic and elemental characteristics of magma bodies, but an evaluation of the mass and thermal constraints on such a process suggest large-scale fluid-melt interaction at liquidus temperatures is unlikely. In the case of the magma body associated with the Campanian Ignimbrite, the most likely source of open-system signatures is assimilation of partial melts of compositionally heterogeneous basement composed of older cumulates and intrusive equivalents of volcanic activity within the Campanian region. Additional trace element modeling, explicitly evaluating the mass and energy balance effects that fluid, solids, and melt have on trace element evolution, will further elucidate the contributions of open vs. closed system processes within the Campanian magma body.

[Rapid determination of major and trace elements in the salt lake clay minerals by X-ray fluorescence spectrometry].

PubMed

Wang, Xiao-Huan; Meng, Qing-Fen; Dong, Ya-Ping; Chen, Mei-Da; Li, Wu

2010-03-01

A rapid multi-element analysis method for clay mineral samples was described. This method utilized a polarized wave-length dispersive X-ray fluorescence spectrometer--Axios PW4400, which had a maximum tube power of 4 000 watts. The method was developed for the determination of As, Mn, Co, Cu, Cr, Dy, Ga, Mo, P, Pb, Rb, S, Sr, Ni, ,Cs, Ta, Th, Ti, U, V, Y, Zn, Zr, MgO, K2O, Na2O, CaO, Fe2O3, Al2O3, SiO2 and so on. Thirty elements in clay mineral species were measured by X-ray fluorescence spectrometry with pressed powder pellets. Spectral interferences, in particular the indirect interferences of each element, were studied. A method to distinguish the interference between each other periodic elements in element periodic table was put forward. The measuring conditions and existence were mainly investigated, and the selected background position as well as corrected spectral overlap for the trace elements were also discussed. It was found that the indirect spectral overlap line was the same important as direct spectral overlap line. Due to inducing the effect of indirect spectral overlap, some elements jlike Bi, Sn, W which do not need analysis were also added to the elements channel. The relative standard deviation (RSD) was in the range of 0.01% to 5.45% except three elements Mo, Cs and Ta. The detection limits, precisions and accuracies for most elements using this method can meet the requirements of sample analysis in clay mineral species.

Characterization of frictional melting processes in subduction zone faults by trace element and isotope analyses

NASA Astrophysics Data System (ADS)

Ishikawa, T.; Ujiie, K.

2017-12-01

Pseudotachylytes found in exhumed accretionary complexes, which are considered to be formed originally at seismogenic depths, are of great importance for elucidating frictional melting and concomitant dynamic weakening of the fault during earthquake in subduction zones. However, fluid-rich environment of the subduction zone faults tends to cause extensive alteration of the pseudotachylyte glass matrix in later stages, and thus it has been controversial that pseudotachylytes are rarely formed or rarely preserved. Chemical analysis of the fault rocks, especially on fluid-immobile trace elements and isotopes, can be a useful means to identify and quantify the frictional melting occurred in subduction zone faults. In this paper, we report major and trace element and Sr isotope compositions for pseudotachylyte-bearing dark veins and surrounding host rocks from the Mugi area of the Shimanto accretionary complex (Ujiie et al., J. Struct. Geol. 2007). Samples were collected from a rock chip along the microstructure using a micro-drilling technique, and then analyzed by ICP-MS and TIMS. Major element compositions of the dark veins showed a clear shift from the host rock composition toward the illite composition. The dark veins, either unaltered or completely altered, were also characterized by extreme enrichment in some of the trace elements such as Ti, Zr, Nb and Th. These results are consistent with disequilibrium melting of the fault zone. Model calculations revealed that the compositions of the dark veins can be produced by total melting of clay-rich matrix in the source rock, leaving plagioclase and quartz grains almost unmolten. The calculations also showed that the dark veins are far more enriched in melt component than that expected from the source rock compositions, suggesting migration and concentration of frictional melt during the earthquake faulting. Furthermore, Sr isotope data of the dark veins implied the occurrence of frictional melting in multiple stages. These results demonstrate that trace element and isotope analyses are useful not only to detect preexistence of pseudotachylytes but also to evaluate the frictional melting in subduction zone faults quantitatively.

Trace elements transport in western Siberia rivers across a permafrost gradient

NASA Astrophysics Data System (ADS)

Pokrovsky, O. S.; Manasypov, R. M.; Loiko, S.; Krickov, I. A.; Kopysov, S. G.; Kolesnichenko, L. G.; Vorobyev, S. N.; Kirpotin, S. N.

2015-11-01

Towards a better understanding of trace element transport in permafrost-affected Earth surface environments, we sampled ∼ 60 large and small rivers (< 100 to ≤ 150 000 km2 watershed area) of Western Siberia Lowland (WSL) during spring flood and summer and winter base-flow across a 1500 km latitudinal gradient covering continuous, discontinuous, sporadic and permafrost-free zones. Analysis of ∼ 40 major and trace elements in dissolved (< 0.45 μm) fraction allowed establishing main environmental factors controlling the transport of metals and trace elements in rivers of this environmentally important region. No statistically significant effect of the basin size on most TE concentration was evidenced. Three category of trace elements were distinguished according to their concentration - latitude pattern: (i) increasing northward in spring and winter (Fe, Al, Ga (only winter), Ti (only winter), REEs, Pb, Zr, Hf, Th (only winter)), linked to leaching from peat and/or redox processes and transport in the form of Fe-rich colloids, (ii) decreasing northward during all seasons (Sr, Mo, U, As, Sb) marking the underground water influence of river feeding and (iii) elements without distinct trend from S to N whose variations within each latitude range were higher than the difference between latitudinal ranges (B, Li, Ti (except summer), Cr, V, Mn, Zn, Cd, Cs, Hf, Th). In addition to these general features, specific, northward increase during spring period was mostly pronounced for Fe, Mn, Co, Zn and Ba and may stem from a combination of enhanced leaching from the topsoil and vegetation and bottom waters of the lakes (spring overturn). A spring time northward decrease was observed for Ni, Cu, Zr, Rb. The southward increase in summer was strongly visible for Fe, Ni, Ba, Rb and V, probably due to peat/moss release (Ni, Ba, Rb) or groundwater feeding (Fe, V). The Principal Component Analysis demonstrated two main factors potentially controlling the ensemble of TE concentration variation. The first factor, responsible for 16-20 % of overall variation, included trivalent and tetravalent hydrolysates, Cr, V, and DOC and presumably reflected the presence of organo-mineral colloids, as also confirmed by previous studies in Siberian rivers. The 2nd factor (8-14 % variation) was linked to the latitude of the watershed and acted on elements affected by the groundwater feeding (DIC, Sr, Mo, As, Sb, U), whose concentration decreased significantly northward during all seasons. Overall, the rank of environmental factors on TE concentration in western Siberian rivers was latitude (3 permafrost zones) > season > watershed size. The effect of the latitude was minimal in spring for most TE but highly visible for Sr, Mo, Sb and U. The main factors controlling the shift of river feeding from surface and subsurface flow to deep underground flow in the permafrost-bearing zone were the depth of the active (unfrozen) seasonal layer and its position in organic or mineral horizons of the soil profile. In the permafrost-free zone, the relative role of carbonate mineral-bearing base rock feeding vs. bog water feeding determined the pattern of trace element concentration and fluxes in rivers of various size as a function of season. Comparison of obtained TE fluxes in WSL rivers with those of other subarctic rivers demonstrated reasonable agreement for most trace elements; the lithology of base rocks was the major factor controlling the magnitude of TE fluxes. The climate change in western Siberia and permafrost boundary migration will affect essentially the elements controlled by underground water feeding (DIC, alkaline-earth elements (Ca, Sr), oxyanions (Mo, Sb, As) and U). The thickening of the active layer may increase the export of trivalent and tetravalent hydrolysates in the form of organo-ferric colloids. Plant litter-originated divalent metals present as organic complexes may be retained via adsorption on mineral horizon. However, due to various counterbalanced processes controlling element source and sinks in plants - peat - mineral soil - river systems, the overall impact of the permafrost thaw on TE export from the land to the ocean may be smaller than that foreseen by merely active layer thickening and permafrost boundary shift.

The Surtsey Magma Series.

PubMed

Schipper, C Ian; Jakobsson, Sveinn P; White, James D L; Michael Palin, J; Bush-Marcinowski, Tim

2015-06-26

The volcanic island of Surtsey (Vestmannaeyjar, Iceland) is the product of a 3.5-year-long eruption that began in November 1963. Observations of magma-water interaction during pyroclastic episodes made Surtsey the type example of shallow-to-emergent phreatomagmatic eruptions. Here, in part to mark the 50(th) anniversary of this canonical eruption, we present previously unpublished major-element whole-rock compositions, and new major and trace-element compositions of sideromelane glasses in tephra collected by observers and retrieved from the 1979 drill core. Compositions became progressively more primitive as the eruption progressed, with abrupt changes corresponding to shifts between the eruption's four edifices. Trace-element ratios indicate that the chemical variation is best explained by mixing of different proportions of depleted ridge-like basalt, with ponded, enriched alkalic basalt similar to that of Iceland's Eastern Volcanic Zone; however, the systematic offset of Surtsey compositions to lower Nb/Zr than other Vestmannaeyjar lavas indicates that these mixing end members are as-yet poorly contained by compositions in the literature. As the southwestern-most volcano in the Vestmannaeyjar, the geochemistry of the Surtsey Magma Series exemplifies processes occurring within ephemeral magma bodies on the extreme leading edge of a propagating off-axis rift in the vicinity of the Iceland plume.

Distribution of Heavy Metals in Surface Sediments of the Bay of Bengal Coast

PubMed Central

Hasan, M. R.; Khan, M.; Aktar, S.; Fatema, K.

2017-01-01

The concentrations of major (Si, Al, Ca, Fe, and K) and minor (Cd, Mn, Ni, Pb, U, Zn, Co, Cr, As, Cu, Rb, Sr, and Zr,) elements in the surficial sediments were studied in an attempt to establish their concentration in the Bengal coast. It was revealed that the majority of the trace elements have been introduced into the Bengal marine from the riverine inflows that are also affected by the impact of industrial, ship breaking yard, gas production plant, and urban wastes. The concentration of heavy metals was measured using Atomic Absorption Spectroscopy and Energy Dispersive X-ray fluorescence instruments. The highest concentrations for several trace elements were thus recorded which generally decrease with distance from the coast. It was observed that the heavy metal concentrations in the sediments generally met the criteria of international marine sediment quality. However, both the contamination factor and pollution load index values suggested the elevation of some metals' concentrations in the region. Constant monitoring of the Bengal coast water quality needs to be recorded with a view to minimizing the risk of health of the population and the detrimental impacts on the aquatic ecosystem. PMID:28255298

Element distribution patterns in the ordovician Galena group, Southeastern Minnesota: Indicators of fluid flow and provenance of terrigenous material

USGS Publications Warehouse

Lively, R.S.; Morey, G.B.; Mossler, J.H.

1997-01-01

As part of a regional geochemical investigation of lower Paleozoic strata in the Hollandale embayment of southeastern Minnesota, elemental concentrations in acid-insoluble residues were determined for carbonate rock in the Middle Ordovician Galena Group. Elemental distribution patterns within the insoluble residues, particularly those of Ti, Al, and Zr, show that the Wisconsin dome and the Wisconsin arch, which contributed sediment to the embayment prior to Galena time, continued as weak sources of sediment during this period. In contrast, trace metals commonly associated with Mississippi Valley-type lead-zinc mineralization, including Pb, Zn, Cu, Ag, Ni, Co, As, and Mo, show dispersal patterns that are independent of those associated with primary depositional phenomena. These trace metals are concentrated in southern Minnesota in carbonate rocks near the interface between limestone- and dolostone-dominated strata. Dispersal patterns imply that the metals were carried by a north-flowing regional ground-water system. The results show that the geochemical attributes of insoluble residues can be used to distinguish provenance and transport directions of primary sediments within a depositional basin from effects of subsequent regional ground-water flow systems.

Multiple melt bodies fed the AD 2011 eruption of Puyehue-Cordón Caulle, Chile.

PubMed

Alloway, B V; Pearce, N J G; Villarosa, G; Outes, V; Moreno, P I

2015-12-02

Within the volcanological community there is a growing awareness that many large- to small-scale, point-source eruptive events can be fed by multiple melt bodies rather than from a single magma reservoir. In this study, glass shard major- and trace-element compositions were determined from tephra systematically sampled from the outset of the Puyehue-Cordón Caulle (PCC) eruption (~1 km(3)) in southern Chile which commenced on June 4(th), 2011. Three distinct but cogenetic magma bodies were simultaneously tapped during the paroxysmal phase of this eruption. These are readily identified by clear compositional gaps in CaO, and by Sr/Zr and Sr/Y ratios, resulting from dominantly plagioclase extraction at slightly different pressures, with incompatible elements controlled by zircon crystallisation. Our results clearly demonstrate the utility of glass shard major- and trace-element data in defining the contribution of multiple magma bodies to an explosive eruption. The complex spatial association of the PCC fissure zone with the Liquiñe-Ofqui Fault zone was likely an influential factor that impeded the ascent of the parent magma and allowed the formation of discrete melt bodies within the sub-volcanic system that continued to independently fractionate.

Effects of Laser Power Level on Microstructural Properties and Phase Composition of Laser-Clad Fluorapatite/Zirconia Composite Coatings on Ti6Al4V Substrates

PubMed Central

Chien, Chi-Sheng; Liu, Cheng-Wei; Kuo, Tsung-Yuan

2016-01-01

Hydroxyapatite (HA) is one of the most commonly used materials for the coating of bioceramic titanium (Ti) alloys. However, HA has poor mechanical properties and a low bonding strength. Accordingly, the present study replaces HA with a composite coating material consisting of fluorapatite (FA) and 20 wt % yttria (3 mol %) stabilized zirconia (ZrO2, 3Y-TZP). The FA/ZrO2 coatings are deposited on Ti6Al4V substrates using a Nd:YAG laser cladding system with laser powers and travel speeds of 400 W/200 mm/min, 800 W/400 mm/min, and 1200 W/600 mm/min, respectively. The experimental results show that a significant inter-diffusion of the alloying elements occurs between the coating layer (CL) and the transition layer (TL). Consequently, a strong metallurgical bond is formed between them. During the cladding process, the ZrO2 is completely decomposed, while the FA is partially decomposed. As a result, the CLs of all the specimens consist mainly of FA, Ca4(PO4)2O (TTCP), CaF2, CaZrO3, CaTiO3 and monoclinic phase ZrO2 (m-ZrO2), together with a small amount of θ-Al2O3. As the laser power is increased, CaO, CaCO3 and trace amounts of tetragonal phase ZrO2 (t-ZrO2) also appear. As the laser power increases from 400 to 800 W, the CL hardness also increases as a result of microstructural refinement and densification. However, at the highest laser power of 1200 W, the CL hardness reduces significantly due to the formation of large amounts of relatively soft CaO and CaCO3 phase. PMID:28773503

Mechanical Properties of Low-Density, Refractory Multi-Principal Element Alloys of the Cr-Nb-Ti-V-Zr System (Postprint)

DTIC Science & Technology

2014-04-01

PROPERTIES OF LOW-DENSITY, REFRACTORY MULTI-PRINCIPAL ELEMENT ALLOYS OF THE Cr– Nb –Ti–V– Zr SYSTEM (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b...element alloys of the Cr– Nb –Ti–V– Zr systemO.N. Senkov n, S.V. Senkova, D.B. Miracle, C. Woodward Air Force Research Laboratory, Materials and...densities below 7.0 g/cm3 have recently been produced by alloying Nb (rNb¼8.57 g/cm3) with four low density refractory elements, V (rV¼6.11 g/cm3), Zr

Hydrothermal Links Between the Caribbean Plateau and OAE2

NASA Astrophysics Data System (ADS)

Duncan, R. A.; Snow, L. J.

2003-12-01

A popular current model for the sporadic occurrence of ocean anoxic events (OAEs) in the Cretaceous ties hydrothermally-induced changes in ocean chemistry (bio-limiting trace metals) during ocean plateau (LIP) volcanism to increased surface productivity, followed by mid-to-deep water oxygen depletion and accumulation of organic-rich sediments. This proposed connection is far from accepted, and important unresolved aspects include the timing of events and yet-to-be-proved synchroneity of volcanism and OAEs, the sensitivity of phytoplankton to bio-limiting (and toxic) trace metals, the difference in biotic responses at various OAEs, and the source of the hydrothermal inputs (sea floor spreading centers or ocean plateaus). To test this hypothesis we have measured the distribution of major, minor and trace element abundances in five pelagic carbonate and black shale sequences that bracket the OAE2, defined by a prominent positive excursion in the global seawater d13C record. Sedimentary sections at Rock Creek Canyon (Pueblo, CO), ODP Site 1138 (Kerguelen Plateau), Bass River (NJ), Totuma well (Venezuela) and Baranca el Canyon (Mexico) were chosen to examine potential trace metal patterns and gradients around the proposed source of hydrothermal inputs - the Caribbean Plateau, whose initial volcanic activity has been dated at 93-89 Ma. ICP-AES and ICP-MS elemental abundances from whole rock samples are normalized to Zr to remove the effect of terrestrial inputs. We find prominent trace metal "spikes" (up to 50 times background) for elements known to be concentrated in volatile degassing of magmas and in hydrothermal plumes resulting from seawater-rock reactions. These anomalies begin at the onset and continue well into the d13C excusion at all five sites. Furthermore, the magnitude of the anomalies decreases with distance from the Caribbean region, and the pattern of elements shifts from a wide range of metals near-source to predominantly long residence time metals far "downstream".

Laser-ablation ICP-MS as a tool for whole rock trace element analyses on fused powders

NASA Astrophysics Data System (ADS)

Girard, G.; Rooney, T. O.

2013-12-01

Here we present an accurate and precise technique for routine trace element analysis of geologic materials by laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We focus on rock powders previously prepared for X-ray fluorescence by fusion in a Li2B4O7 flux, and subsequently quenched in a Pt mold to form a glass disk. Our method allows for the analysis up to 30 trace elements by LA-ICP-MS using a Photon-Machines Analyte G2 193 nm excimer laser coupled to a Thermo-Fisher Scientific ICAP Q quadrupole ICP-MS. Analyses are run as scans on the surface of the disks. Laser ablation conditions for which trace element fractionation effects are minimal have been empirically determined to be ~ 4 J m-2 fluence, at 10 Hz , and 10 μm s-1 scan speed, using a 110 μm laser beam size. Ablated material is carried into the ICP-MS by a He carrier at a rate of 0.75 L min-1. Following pre-ablation to remove surface particles, samples are ablated for 200 s, of which 140 s are used for data acquisition. At the end of each scan, a gas blank is collected for 30 s. Dwell times for each element vary between 15 and 60 μs, depending on abundance and instrument sensitivity, allowing 120 readings of each element during the data acquisition time window. To correct for variations in the total volume of material extracted by the laser, three internal standards are used, Ca, Fe and Zr. These elements are routinely analyzed by X-ray fluorescence by the Geoanalytical laboratory at Michigan State University with precision and accuracy of <5%. The availability of several internal standards allows for better correction of possible persisting laser ablation fractionation effects; for a particular trace element, we correct using the internal standard that best reproduces its ablation behavior. Our calibration is based on a combination of fused powders of US Geological Survey and Geological Survey of Japan rock standards, NIST SRM 612 glass, and US Geological Survey natural and synthetic basalt glasses. Instrumental drift is monitored during each run using two fused standards analyzed multiple times as unknowns. We routinely achieve an external precision of <5% on multiple replicates of standards run as unknowns, which are also within <5% of certified values. Elements analyzed include most first row transition metals, large ion lithophile elements, high field strength elements, lanthanide and actinide rare earth elements.

Total elemental composition of soils contaminated with wastewater irrigation by combining IBA techniques

NASA Astrophysics Data System (ADS)

Huerta, L.; Contreras-Valadez, R.; Palacios-Mayorga, S.; Miranda, J.; Calva-Vasquez, G.

2002-04-01

The purpose of this work was to obtain the total elemental composition of agricultural soils irrigated with well water and wastewater. The studied area is located in the Valle del Mezquital in Hidalgo State, Mexico. The studied soils were collected, every two months during one year. Particle induced X-ray emission (PIXE), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) were applied for elemental analysis. PIXE analyses gave elemental contents of major and trace elements (Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Rb, Sr, Y, Zr, and Pb). Total concentrations of Na, Mg, C, N and O were obtained by RBS and NRA. PIXE analyses were carried out with 2 MeV proton beams, RBS with 2 MeV helium ions, while NRA was applied with a 1.2 MeV deuterium beam. Results indicated that heavy metal total concentrations exceed the critical soil total concentrations according to environmental regulations.

Trace-element evidence for the origin of desert varnish by direct aqueous atmospheric deposition

NASA Astrophysics Data System (ADS)

Thiagarajan, Nivedita; Aeolus Lee, Cin-Ty

2004-07-01

Smooth rock surfaces in arid environments are often covered with a thin coating of Fe-Mn oxyhydroxides known as desert varnish. It is debated whether such varnish is formed (a) by slow diagenesis of dust particles deposited on rock surfaces, (b) by leaching from the underlying rock substrate, or (c) by direct deposition of dissolved constituents in the atmosphere. Varnishes collected from smooth rock surfaces in the Mojave Desert and Death Valley, California are shown here to have highly enriched and fractionated trace-element abundances relative to upper continental crust (UCC). They are highly enriched in Co, Ni, Pb and the rare-earth elements (REEs). In particular, they have anomalously high Ce/La and low Y/Ho ratios. These features can only be explained by preferential scavenging of Co, Ni, Pb and the REEs by Fe-Mn oxyhydroxides in an aqueous environment. High field strength elements (HFSEs: Zr, Hf, Ta, Nb, Th), however, show only small enrichments despite the fact that these elements should also be strongly scavenged by Fe-Mn oxyhydroxides. This suggests that their lack of enrichment is a feature inherited from a solution initially poor in HFSEs. The first two scenarios for varnish formation can be ruled out as follows. The high enrichment factors of Fe, Mn and many trace elements cannot be generated by mass loss associated with post-depositional diagenesis of dust particles because such a process predicts only a small increase in concentration. In addition, the highly fractionated abundance patterns of particle reactive element pairs (e.g., Ce/La and Y/Ho) rules out leaching of the rock substrate. This is because if leaching were to occur, varnishes would grow from the inside to the outside, and thus any particle-reactive trace element leached from the substrate would be quantitatively sequestered in the Fe-Mn oxyhydroxide layers, prohibiting any significant elemental fractionations. One remaining possibility is that the Fe, Mn and trace metals in varnish are derived from leaching of dust particles entrained in rain or fog droplets either in the atmosphere or during wet atmospheric deposition. The high trace metal enrichment factors require that most of the dust was physically removed before or during varnish formation. The remaining aqueous counterpart would be depleted in HFSEs and Th relative to the REEs, Co, Ni and Pb because the former are more insoluble and hence largely retained in the removed dust fraction. The high Ce/La ratios suggest that precipitation of trace metals may have been governed by equilibrium partitioning in an excess of wet atmospheric deposition. If varnishes are indeed derived from wet atmospheric deposition, they may provide a record of the aqueous component of atmospheric dust inputs to various environments.

A new Mantle Source Tapped During Episode 55 of the Pu'u O'o Eruption From Kilauea Volcano

NASA Astrophysics Data System (ADS)

Marske, J. P.; Pietruszka, A. J.; Garcia, M. O.; Rhodes, J. M.

2005-12-01

Over 22 years of continuous geochemical monitoring of lavas from the current Pu'u O'o eruption allows us to probe the mantle and crustal processes beneath Kilauea Volcano in unparalleled detail. Episode 55 (1997-present) marks the longest and most voluminous Pu'u O'o eruptive interval. Here we present new Pb, Sr, and Nd isotopic ratios and major- and trace-element abundances for the most recent lavas (1999-2005). MgO variation diagrams show that most of the major-element variations are related to olivine fractionation. However, Pu'u O'o lavas display longer-term systematic decreases in their TiO2, K2O, P2O5 and CaO abundances (at a given MgO) due to changes in the parental magma composition. Incompatible element ratios (K2O/TiO2, Nb/Y, Nb/Zr) and MgO-normalized abundances (Sr, Rb, K) in episode 55 lavas delimit the lowest values observed during the Pu'u O'o eruption. Earlier Pu'u O'o lavas displayed a temporal decrease in highly over moderately incompatible trace-element ratios, near constant SiO2 contents, and a gradual increase in 87Sr/86Sr. However, episode 55 lavas (between days 5500-6500) record an increase in MgO-normalized SiO2 contents and even higher 87Sr/86Sr with near constant incompatible trace-element ratios. Neither a single mantle source composition nor a change in partial melting conditions can explain these observations. Based on 226Ra-230Th-238U disequilibria and partial melting modeling of trace elements, we conclude that Pu'u O'o lavas originate from at least two distinct mantle source components: (1) a recently depleted component that was subsequently remelted to explain the overall decreases of incompatible major- and trace-element ratios and abundances, and (2) a compositionally and isotopically distinct mantle component that was not previously melted within the Hawaiian plume to explain the temporal increase in 87Sr/86Sr and SiO2 abundances and the flattening trend of incompatible trace-element ratios. This second component lies within typical Pb, Sr and Nd isotopic space for Kilauea, but represents a new source composition for the Pu'u O'o eruption. These results can be explained by a recent (1999) change in the size or location of Pu'u O'o's melting region, which allowed this new source to be tapped.

A mass-balance model to separate and quantify colloidal and solute redistributions in soil

USGS Publications Warehouse

Bern, C.R.; Chadwick, O.A.; Hartshorn, A.S.; Khomo, L.M.; Chorover, J.

2011-01-01

Studies of weathering and pedogenesis have long used calculations based upon low solubility index elements to determine mass gains and losses in open systems. One of the questions currently unanswered in these settings is the degree to which mass is transferred in solution (solutes) versus suspension (colloids). Here we show that differential mobility of the low solubility, high field strength (HFS) elements Ti and Zr can trace colloidal redistribution, and we present a model for distinguishing between mass transfer in suspension and solution. The model is tested on a well-differentiated granitic catena located in Kruger National Park, South Africa. Ti and Zr ratios from parent material, soil and colloidal material are substituted into a mixing equation to quantify colloidal movement. The results show zones of both colloid removal and augmentation along the catena. Colloidal losses of 110kgm-2 (-5% relative to parent material) are calculated for one eluviated soil profile. A downslope illuviated profile has gained 169kgm-2 (10%) colloidal material. Elemental losses by mobilization in true solution are ubiquitous across the catena, even in zones of colloidal accumulation, and range from 1418kgm-2 (-46%) for an eluviated profile to 195kgm-2 (-23%) at the bottom of the catena. Quantification of simultaneous mass transfers in solution and suspension provide greater specificity on processes within soils and across hillslopes. Additionally, because colloids include both HFS and other elements, the ability to quantify their redistribution has implications for standard calculations of soil mass balances using such index elements. ?? 2011.

The role of African dust in the formation of Quaternary soils on Mallorca, Spain and implications for the genesis of Red Mediterranean soils

USGS Publications Warehouse

Muhs, D.R.; Budahn, J.; Avila, A.; Skipp, G.; Freeman, J.; Patterson, D.

2010-01-01

African dust additions explain the origin of terra rossa soils that are common on the carbonate-platform island of Mallorca, Spain. Mineralogical and geochemical analyses indicate that Quaternary carbonate eolianites on Mallorca have a very high purity, usually composed of more than 90% carbonate minerals (calcite, dolomite, and aragonite). In contrast, terra rossa soils developed on these eolianites have lower carbonate contents and contain higher concentrations of quartz and other silicates. Analyses of immobile trace elements indicate that the non-carbonate fractions of the eolianites have distinctive Zr/Hf, La/Yb, Cr/Sc and Th/Ta values that differ from the superjacent terra rossa soils. These observations indicate that even if sufficient dissolution of the eolianite had taken place to create the soils by residual accumulation, immobile element ratios in the soils require an external source. However, Zr/Hf, La/Yb, Cr/Sc and Th/Ta values in the soils fall within the range of values for these element ratios in African dust collected on Barbados and mainland Spain. We conclude that the silicate fractions of terra rossa soils on Mallorca are derived mainly, though not wholly, from far-traveled African dust, and this process may explain the origin of other terra rossa soils found in southern Europe. ?? 2010.

Reducing the Ideal Shear Strengths of ZrB2 by High Efficient Alloying Elements (Ag, Au, Pd and Pt)

NASA Astrophysics Data System (ADS)

Dai, Fu-Zhi; Zhou, Yanchun

2017-02-01

Activating the plasticity of ZrB2 is a promising approach to improve its key properties for applications in hypersonic vehicles, including high temperature strength and thermal shock resistance. The present work demonstrates that ideal shear strength of ZrB2, which is a good indicator of the critical stress for dislocation nucleation, can be significantly reduced by dissolving of appropriate alloying elements. Analyzing on the bonding nature of ZrB2 reveals that choosing alloying elements with low energy valence electrons will prevent electron transferring from alloying element to the electron deficient B-B π orbits, which will reduce the local stability of the region surrounding the alloying element. Under the criterion, elements with d electrons tending to be full-filled (Ag, Au, Pd and Pt, the full-filled state is associated with low energy level) are selected as promising candidates with their prominent efficiency in reducing ideal shear strengths verified by first-principles calculations. The results provide useful guidelines for further designs of ZrB2 based materials, especially for improving their mechanical properties.

Reducing the Ideal Shear Strengths of ZrB2 by High Efficient Alloying Elements (Ag, Au, Pd and Pt)

PubMed Central

Dai, Fu-Zhi; Zhou, Yanchun

2017-01-01

Activating the plasticity of ZrB2 is a promising approach to improve its key properties for applications in hypersonic vehicles, including high temperature strength and thermal shock resistance. The present work demonstrates that ideal shear strength of ZrB2, which is a good indicator of the critical stress for dislocation nucleation, can be significantly reduced by dissolving of appropriate alloying elements. Analyzing on the bonding nature of ZrB2 reveals that choosing alloying elements with low energy valence electrons will prevent electron transferring from alloying element to the electron deficient B-B π orbits, which will reduce the local stability of the region surrounding the alloying element. Under the criterion, elements with d electrons tending to be full-filled (Ag, Au, Pd and Pt, the full-filled state is associated with low energy level) are selected as promising candidates with their prominent efficiency in reducing ideal shear strengths verified by first-principles calculations. The results provide useful guidelines for further designs of ZrB2 based materials, especially for improving their mechanical properties. PMID:28233838

Reducing the Ideal Shear Strengths of ZrB2 by High Efficient Alloying Elements (Ag, Au, Pd and Pt).

PubMed

Dai, Fu-Zhi; Zhou, Yanchun

2017-02-24

Activating the plasticity of ZrB 2 is a promising approach to improve its key properties for applications in hypersonic vehicles, including high temperature strength and thermal shock resistance. The present work demonstrates that ideal shear strength of ZrB 2 , which is a good indicator of the critical stress for dislocation nucleation, can be significantly reduced by dissolving of appropriate alloying elements. Analyzing on the bonding nature of ZrB 2 reveals that choosing alloying elements with low energy valence electrons will prevent electron transferring from alloying element to the electron deficient B-B π orbits, which will reduce the local stability of the region surrounding the alloying element. Under the criterion, elements with d electrons tending to be full-filled (Ag, Au, Pd and Pt, the full-filled state is associated with low energy level) are selected as promising candidates with their prominent efficiency in reducing ideal shear strengths verified by first-principles calculations. The results provide useful guidelines for further designs of ZrB 2 based materials, especially for improving their mechanical properties.

Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds

NASA Astrophysics Data System (ADS)

Yang, Xiao; Li, Huijian; Hu, Minzheng; Liu, Zeliang; Wärnå, John; Cao, Yuying; Ahuja, Rajeev; Luo, Wei

2018-04-01

A method to obtain the equivalent Poisson's ratio in chemical bonds as classical beams with finite element method was proposed from experimental data. The UFF (Universal Force Field) method was employed to calculate the elastic force constants of Zrsbnd O bonds. By applying the equivalent Poisson's ratio, the mechanical properties of single-wall ZrNTs (ZrO2 nanotubes) were investigated by finite element analysis. The nanotubes' Young's modulus (Y), Poisson's ratio (ν) of ZrNTs as function of diameters, length and chirality have been discussed, respectively. We found that the Young's modulus of single-wall ZrNTs is calculated to be between 350 and 420 GPa.

Geochemical patterns in soils in and around Siddipet, Medak District, Andhra Pradesh, India.

PubMed

Dantu, Sujatha

2010-11-01

This paper reports the first results of geochemical survey carried out in and around Siddipet, taking soil (topsoil 0-25 cm and subsoil 70-95 cm) as the sampling media. The data were obtained in a consistent way from 61 sites. The samples were analyzed for 29 elements (As, Ba, Cd, Co, Cr, Cu, F, Mo, Ni, Pb, Rb, Se, Sr, Th, U, V, Y, Zn, Zr, Si, Al, Fe, Mn, Mg, Ca, Na, K, Ti, and P) by X-ray fluorescence spectrometer, and baseline levels for these elements are presented. Results reveal that the correlation between the geochemical patterns in the soils developed on different litho-variants is not straight forward, but some general trends can be observed. Regional parent materials and pedogenesis are the primary factors influencing the concentrations of trace elements while anthropogenic activities have secondary influence.

Volatility in the lunar crust: Trace element analyses of lunar minerals by PIXE proton microprobe

NASA Technical Reports Server (NTRS)

Norman, M. D.; Griffin, W. L.; Ryan, C. G.

1993-01-01

In situ determination of mineral compositions using microbeam techniques can characterize magma compositions through mineral-melt partitioning, and be used to investigate fine-grained or rare phases which cannot be extracted for analysis. Abundances of Fe, Mn, Sr, Ga, Zr, Y, Nb, Zn, Cu, Ni, Se, and Sb were determined for various mineral phases in a small number of lunar highlands rocks using the PIXE proton microprobe. Sr/Ga ratios of plagioclase and Mn/Zn ratios of mafic silicates show that the ferroan anorthosites and Mg-suite cumulates are depleted in volatile lithophile elements to about the same degree compared with chondrites and the Earth. This links the entire lunar crust to common processes or source compositions. In contrast, secondary sulfides in Descartes breccia clasts are enriched in chalcophile elements such as Cu, Zn, Ni, Se, and Sb, and represent a potential resource in the lunar highlands.

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.

HAIR HEAVY METAL AND ESSENTIAL TRACE ELEMENT CONCENTRATION IN CHILDREN WITH AUTISM SPECTRUM DISORDER.

PubMed

Tabatadze, T; Zhorzholiani, L; Kherkheulidze, M; Kandelaki, E; Ivanashvili, T

2015-11-01

Our study aims evaluation of level of essential trace elements and heavy metals in the hair samples of children with autistic spectrum disorder (ASD) and identification of changes that are associated with autistic spectrum disorders. Case-control study was conducted at Child Development Center of Iashvili Children's Central Hospital (LD).We studied 60 children aged from 4 to 5 years old. The concentrations of 28 elements among (Ca,Zn, K, Fe, Cu, Se, Mn, Cr, S, Br, Cl, Co, Ag, V, Ni, Rb, Mo, Sr, Ti, Ba, Pb, As, Hg, Cd, Sb, Zr, Sn, Bi) them trace elements and toxic metals) were determined in scalp hair samples of children (n=30) with autistic spectrum disorder (ASD) and from control group of healthy children (n=30) with matched sex and age. Micro-elemental status was detected in the hair, with roentgen-fluorescence spectrometer method (Method MBИ 081/12-4502-000, Apparatus ALVAX- CIP, USA - UKRAIN) .To achieve the similarity of study and control groups, pre and postnatal as well as family and social history were assessed and similar groups were selected. Children with genetic problems, malnourished children, children from families with social problems were excluded from the study. The diagnosis of ASD were performed by pediatrician and psychologist (using M-CHAT and ADOS) according to DSM IV (Diagnostic and Statistical Manual of Mental Disorders from the American Psychiatric association) criteria. The study was statistically analyzed using computer program SPSS 19. Deficiencies of essential trace microelements revealed in both group, but there was significant difference between control and studied groups. The most deficient element was zinc (92% in target and 20% in control), then - manganese (55% and 8%) and selenium (38% and 4%). In case of cooper study revealed excess concentration of this element only in target group in 50% of cases. The contaminations to heavy metals were detected in case of lead (78% and 16), mercury (43% and 10%) and cadmium (38% and 8%). The study statistical results indicated, that deficient concentrations of trace elements such as zinc, manganese, molybdenum and selenium in hair significantly linked with ASD (Kramer's V was 0,740; 0,537; 0,333; 0,417 accordingly). In case of cooper we got excess levels of this element and this data was highly linked with autism spectrum disorder. We got high associations and significant values between of lead, mercury and cadmium concentrations and ASD. Study results indicate that there are significant differences of hair essential trace elements concentrations in children with autism spectrum disorder comparing with healthy children group. The result obtained also showed high contamination to heavy metals such as lead, mercury and cadmium in ASD children compared to healthy ones. So, our study demonstrated alteration in levels of toxic heavy metals and essential trace elements in children with autistic spectrum disorders as compared to healthy children. This suggests a possible pathophysiological role of heavy metals and trace elements in the genesis of symptoms of autism spectrum disorders.

Neogene volcanism associated with back-arc basin tectonics at the northern Fossa Magna, NE Japan

NASA Astrophysics Data System (ADS)

Okamura, S.; Inaba, M.; Shinjo, R.; Adachi, Y.

2016-12-01

New isotopic and trace element data presented here imply a temporal change in magma sources and thermal conditions beneath the northern Fossa Magna of NE Japan from the Miocene to the Pliocene. Rocks from more sediment melt-rich Early Miocene volcanoes have less radiogenic 176Hf/177Hf and 143Nd/144Nd, high Zr/Hf, and little or no Hf anomaly (Hf/Hf*; ˜1.0). The mantle wedge in the Early Miocene consisted of enriched mantle source. We propose that during the onset of subduction, influx of hot asthenospheric mantle provided sufficient heat to partially melt newly subducting sediment. Geochemical modeling results suggest breakdown of zircon in the slab surface sediments for the Early Miocene lavas in the northern Fossa Magna region. In the Middle Miocene, the injection of hot and depleted asthenospheric material replaced the mantle beneath the northern Fossa Magna region of NE Japan. This caused the isotopic signature of the rocks to change from enriched to depleted. The Middle Miocene lavas characterized by most radiogenic Hf and Nd isotope ratios, have high Zr/Hf, low Lu/Hf, and little or no Hf anomaly. An appropriate working petrogenetic model is that the Middle Miocene lavas were derived from asthenospheric depleted mantle, slightly ( < 1%) contaminated by slab melt accompanied by full dissolution of zircon. All the Late Miocene and Pliocene samples are characterized by distinctly more radiogenic 176Hf/177Hf and 143Nd/144Nd, and more negative Hf anomalies (greater Hf/Hf* variability; ˜0.3). The Pliocene samples are displaced toward lower Hf/Hf* and Zr/Hf, and higher Lu/Hf relative to the Middle Miocene samples, which requires mixing between depleted mantle and a partial melt of subducted metasediment saturated with trace quantity of zircon.

Positive anomalous concentrations of Pb in some gabbroic rocks of Afikpo basin southeastern Nigeria.

PubMed

Onwualu-John, J N

2016-08-01

Gabbroic rocks have intruded the sedimentary sequence at Ameta in Afikpo basin southeastern Nigeria. Petrographic and geochemical features of the rocks were studied in order to evaluate their genetic and geotectonic history. The petrographic results show that the rocks contain plagioclase, olivine, pyroxene, biotite, iron oxide, and traces of quartz in three samples. Major element characteristics show that the rocks are subalkaline. In addition, the rocks have geochemical characteristics similar to basaltic andesites. The trace elements results show inconsistent concentrations of high field strength elements (Zr, Nb, Th, Ta), moderate enrichment of large-ion lithophile elements (Rb, Sr, Ba) and low concentrations of Ni and Cr. Rare earth element results show that the rocks are characterized by enrichment of light rare earth elements, middle rare earth elements enrichment, and depletion of heavy rare earth elements with slight positive europium anomalies. Zinc concentrations are within the normal range in basaltic rocks. There are extremely high concentrations of Pb in three of the rock samples. The high Pb concentrations in some of these rocks could be as a result of last episodes of magmatic crystallization. The rocks intruded the Asu River Group; organic components in the sedimentary sequence probably contain Pb which has been assimilated into the magma at the evolutionary stage of the magma. Weathering of some rocks that contain galena could lead to an increase in the concentration of lead in the gabbroic rocks, especially when the migration and crystallization of magma take place in an aqueous environment. Nevertheless, high concentration of lead is hazardous to health and environment.

Petrology of peridotite xenoliths from the Miocene alkaline basalt from Baegryeong Island

NASA Astrophysics Data System (ADS)

Park, G. Y.; Kim, E.; Yang, K.

2017-12-01

Peridotite xenoliths occurring in late Miocene intraplate alkaline basalt from Baegryeong Island, west-northern part of the Korean peninsula, are mainly anhydrous spinel lherzolites. Their textures and chemical compositions give a deep insight for upper mantle. This study presents the results of modal, major composition of minerals and trace composition of clinopyroxene. The xenoliths display coarse grained protogranular through inequigranular to cumulate textures, grading into each other. They often show well-developed annealed textures and contain left-over olivine grains within orthopyroxene, suggesting that they went through static(±dynamic) recrystallization. The constituent minerals are compositionally homogeneous and appear to be equilibrated. The xenoliths are characterized by the high Mg#[=100×Mg/(Mg+Fetotal) atomic ratio] of olivine, orthopyroxene and clinopyroxene (89-93) and the Cr#[=100×Cr/(Cr+Al) atomic ratio] of spinel (9-15). The calculated equilibrium temperatures and oxygen fugacities resulted in 920-1070°C and ΔfO2 (QFM) = -1.5 -0.5, respectively. Clinopyroxenes of the xenoliths are mostly enriched in incompatible trace elements, exhibiting three types of REE patterns such as LREE-depleted, LREE-enriched and a enrichment in La over Ce, and depletion in high field strength elements(HFSE; Nb-Ta, Zr-Hf, Ti). From these trace element signatures, we thus propose the Baegryeong peridotite xenoliths represent residues left after early melt extraction, which was subsequently subjected to different degrees of modal/cryptic metasomatism by residual slab-derived, silica- and LREE-enriched fluids (or melts).

Eolian additions to late Quaternary alpine soils, Indian Peaks Wilderness Area, Colorado Front Range

USGS Publications Warehouse

Muhs, D.R.; Benedict, J.B.

2006-01-01

Surface horizons of many alpine soils on Quaternary deposits in high-mountain settings are enriched in silt. The origin of these particles has been debated, particularly in the Rocky Mountain region of North America. The most common explanations are frost shattering of coarser particles and eolian additions from distant sources. We studied soil A horizons on alpine moraines of late-glacial (Satanta Peak) age in the Colorado Front Range. Surface horizons of soils on these moraines are enriched in silt and have a particle size distribution that resembles loess and dust deposits found elsewhere. The compositions of sand and silt fractions of the soils were compared to possible local source rocks, using immobile trace elements Ti, Nb, Zr, Ce, and Y. The sand fractions of soils have a wide range of trace element ratios, similar to the range of values in the local biotite gneiss bedrock. In contrast, silt fractions have narrower ranges of trace element ratios that do not overlap the range of these ratios in biotite gneiss. The particle size and geochemical results support an interpretation that silts in these soils are derived from airborne dust. Eolian silts were most likely derived from distant sources, such as the semiarid North Park and Middle Park basins to the west. We hypothesize that much of the eolian influx to soils of the Front Range occurred during an early to mid-Holocene warm period, when sediment availability in semiarid source basins was at a maximum.

Concentration, behavior and storage of H/sub 2/O in the suboceanic upper mantle: implications for mantle metasomatism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michael, P.J.

1988-02-01

Mid-ocean ridge basalt glasses from the Pacific-Nazca Ridge and the northern Juan de Fuca Ridge were analyzed for H/sub 2/O by gas chromatography. Incompatible element enriched (IEE) glasses have higher H/sub 2/O contents than depleted (IED) glasses. H/sub 2/O increases systematically with decreasing Mg/Mg + Fe/sup 2 +/ within each group. Near-primary IED MORBs have an average of about 800 ppm H/sub 2/O, while near-primary IEE MORBs (with chondrite normalized Nb/Zr or La/Sm approx. 2) have about 2100 ppm H/sub 2/O. If these basalts formed by 10-20% partial melting then the IED mantle source had 100-180 ppm H/sub 2/O, whilemore » the IEE source had 250-450 ppm H/sub 2/O. The ratio H/sub 2/O/(Ce + Nd) is fairly constant at 95 +/- 30 for all oceanic basalts from the Pacific. During trace element fractionation in the suboceanic upper mantle, H/sub 2/O behaves more compatibly than K, Rb, Nb, and Cl, but less compatibly than Sm, Zr and Ti. H/sub 2/O is contained mostly in amphibole in the shallow upper mantle. At pressures greater than the amphibole stability limit, it is likely that a significant proportion of H/sub 2/O is contained in a mantle phase which is more refractory than phlogopite at these pressures. The role of H/sub 2/O in mantle enrichment processes is examined by assuming that an enriched component was added. The modeled concentrations of K, Na, Ti and incompatible trace elements in this component are high relative to H/sub 2/O, indicating that suboceanic mantle enrichment is caused by silicate melts such as basanites and not by aqueous fluids.« less

Variations of trace element concentration of magnetite and ilmenite from the Taihe layered intrusion, Emeishan large igneous province, SW China: Implications for magmatic fractionation and origin of Fe-Ti-V oxide ore deposits

NASA Astrophysics Data System (ADS)

She, Yu-Wei; Song, Xie-Yan; Yu, Song-Yue; He, Hai-Long

2015-12-01

In situ LA-ICP-MS trace elemental analysis has been applied to magnetite and ilmenite of the Taihe layered intrusion, Emeishan large igneous province, SW China, in order to understand better fractionation processes of magma and origin of Fe-Ti-V oxide ore deposits. The periodic reversals in Mg, Ti, Mn in magnetite and Mg, Sc in ilmenite are found in the Middle Zone of the intrusion and agree with fractionation trends as recorded by olivine (Fo), plagioclase (An) and clinopyroxene (Mg#) compositions. These suggest the Taihe intrusion formed from open magma chamber processes in a magma conduit with multiple replenishments of more primitive magmas. The V and Cr of magnetite are well correlated with V and Cr of clinopyroxene indicating that they became liquidus phases almost simultaneously at an early stage of magma evolution. Ilmenite from the Middle and Upper Zones shows variable Cr, Ni, V, Mg, Nb, Ta and Sc contents indicating that ilmenite at some stratigraphic levels crystallized slightly earlier than magnetite and clinopyroxene. The early crystallization of magnetite and ilmenite is the result of the high FeOt and TiO2 contents in the parental magma. The ilmenite crystallization before magnetite in the Middle and Upper Zones can be attributed to higher TiO2 content of the magma due to the remelting of pre-existing ilmenite in a middle-level magma chamber. Compared to the coeval high-Ti basalts, the relatively low Zr, Hf, Nb and Ta contents in both magnetite and ilmenite throughout the Taihe intrusion indicate that they crystallized from Fe-Ti-(P)-rich silicate magmas. Positive correlations of Ti with Mg, Mn, Sc and Zr of magnetite, and Zr with Sc, Hf and Nb of ilmenite also suggest that magnetite and ilmenite crystallized continuously from the homogeneous silicate magma rather than an immiscible Fe-rich melt. Therefore, frequent replenishments of Fe-Ti-(P)-rich silicate magma and gravitational sorting and settling are crucial for the formation the massive and apatite-rich disseminated ores in the Lower and Middle Zones of the Taihe intrusion.

A recipe for the use of rutile in sedimentary provenance analysis

NASA Astrophysics Data System (ADS)

Triebold, Silke; von Eynatten, Hilmar; Zack, Thomas

2012-12-01

Rutile has received considerable attention in the last decade as a valuable petrogenetic indicator mineral. Based on both new and previously published data, we carve out advantages and pitfalls regarding TiO2-minerals in sedimentary provenance analysis. This results in a recipe for the use of rutile in provenance studies. The main points are: Rutile geochemistry from different grain size fractions does not differ systematically, and hence rutiles should be extracted from the fraction containing the most rutile grains (usually 63-200 μm). Similarly, different magnetic susceptibility of rutile does not systematically imply different trace element composition. Before interpretation of TiO2-mineral data, it is important to determine the polymorph type. Rutile, anatase and brookite appear to differ systematically in trace element composition. As an alternative to Raman spectroscopy, chemical classification according to Nb, Cr, Sn, Fe, V, and Zr concentrations can be applied. For rutile, a new host lithology discrimination scheme based on Cr-Nb systematics is introduced (x = 5 ∗ (Nb [ppm] - 500) - Cr [ppm]), which leads to better classification results than previously published discrimination methods. According to this equation, metamafic rutiles have negative values of x, while metapelitic rutiles have positive values. Evaluation of the growth temperature calculations of metamorphic rutile after different authors shows that the equations given by Tomkins et al. (2007) should be applied to both metamafic and metapelitic rutiles. Although there is a pressure effect on the Zr incorporation in rutile, the pressure range for most rutiles of 5-15 kbar introduces an uncertainty in calculated temperature of no more than ± 35 °C. The distribution of calculated temperatures from detrital rutiles is crucial; only well-defined temperature populations should be used for thermometry interpretation.

Demonstration of femtosecond laser ablation inductively coupled plasma mass spectrometry for uranium isotopic measurements in U-10Mo nuclear fuel foils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Havrilla, George Joseph; Gonzalez, Jhanis

2015-06-10

The use of femtosecond laser ablation inductively coupled plasma mass spectrometry was used to demonstrate the feasibility of measuring the isotopic ratio of uranium directly in U-10Mo fuel foils. The measurements were done on both the flat surface and cross sections of bare and Zr clad U-10Mo fuel foil samples. The results for the depleted uranium content measurements were less than 10% of the accepted U235/238 ratio of 0.0020. Sampling was demonstrated for line scans and elemental mapping over large areas. In addition to the U isotopic ratio measurement, the Zr thickness could be measured as well as trace elementalmore » composition if required. A number of interesting features were observed during the feasibility measurements which could provide the basis for further investigation using this methodology. The results demonstrate the feasibility of using fs-LA-ICP-MS for measuring the U isotopic ratio in U-10Mo fuel foils.« less

Distribution of rubidium, strontium, and zirconium in tuff from two deep coreholes at Yucca Mountain, Nevada

USGS Publications Warehouse

Spengler, Richard W.; Peterman, Zell E.; ,

1991-01-01

Variations in concentrations of trace elements Rb, Sr, and Zr within the sequence of high-silica tuff and dacitic lava beneath Yucca Mountain reflect both primary composition and secondary alteration. Rb and K concentrations have parallel trends. Rb concentrations are significantly lower within intervals containing zeolitic nonwelded to partially welded and bedded tuffs and are higher in thick moderately to densely welded zones. Sr concentrations increase with depth from about 30 ppm in the Topopah Spring Member of the Paintbrush Tuff to almost 300 ppm in the older tuffs. Zr concentrations are about 100 ppm in the Topopah Spring Member and also increase with depth to about 150 ppm in the Lithic Ridge Tuff and upper part of the older tuffs. Conspicuous local high concentrations of Sr in the lower part of the Tram Member, in the dacite lava, and in unit c of the older tuffs in USW G-1, and in the densely welded zone of the Bullfrog Member in USW GU-3/G-3 closely correlate with high concentrations of less-mobile Zr and may reflect either primary composition or elemental redistribution resulting largely from smectitic alteration. Initial 87Sr/86Sr values from composite samples increase upward in units above the Bullfrog Member of the Crater Flat Tuff. The progressive tenfold increase in Sr with depth coupled with the similarity of initial 87Sr/86Sr values within the Bullfrog Member and older units to those of Paleozoic marine carbonates are consistent with a massive influx of Sr from water derived from a Paleozoic carbonate aquifer.

Main components of PM10 in an area influenced by a cement plant in Catalonia, Spain: Seasonal and daily variations.

PubMed

Rovira, Joaquim; Sierra, Jordi; Nadal, Martí; Schuhmacher, Marta; Domingo, José L

2018-05-01

Particulate matter (PM) composition has a key role in a wide range of health outcomes, such as asthma, chronic obstructive pulmonary disease, lung cancer, cardiovascular disease, and death, among others. Montcada i Reixac, a municipality located in the Barcelona metropolitan area (Catalonia, Spain), for its location and orography, is an interesting case- study to investigate air pollution. The area is also characterized by the presence of different industrial emission sources, including a cement factory and a large waste management plant, as well as an intense traffic. In this study, PM 10 levels, trace elements, ions, and carbonaceous particles were determined for a long time period (2013-2016) in this highly polluted area. PM 10 samples were collected during six consecutive days in two campaigns (cold and warm) per year. A number of elements (As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, K, La, Li, Hg, Mg, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Se, Sm, Sn, Sr, Tb, Th, Ti, Tl, U, V, W, Y, Yb, and Zr), ions (Cl - , SO 4 2- , NO 3 - , and NH 4 + ), and carbonaceous content (total carbon, organic plus elemental carbon, and CO 3 2- ), were analysed. These data were used to identify the PM 10 main components: mineral matter, sea spray, secondary inorganic aerosols, organic matter plus elemental carbon, trace elements or indeterminate fraction. Although a clear seasonality (cold vs. warm periods) was found, there were no differences between working days and weekends. Obviously, the cement plant influences the surrounding environment. However, no differences in trace elements related with the cement plant activity (Al, Ca, Ni and V) between weekdays and weekends were noted. However, some traffic-related elements (i.e., Co, Cr, Mn, and Sb) showed significantly higher concentrations in weekdays. Copyright © 2018 Elsevier Inc. All rights reserved.

Major, trace element and isotope geochemistry (Sr-Nd-Pb) of interplinian magmas from Mt. Somma-Vesuvius (Southern Italy)

USGS Publications Warehouse

Somma, R.; Ayuso, R.A.; de Vivo, B.; Rolandi, G.

2001-01-01

Major, trace element 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 element 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 elements (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-element 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 element 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.

Fabrication and Properties of Plasma-Sprayed Al2O3/ZrO2 Composite Coatings

NASA Astrophysics Data System (ADS)

Dejang, N.; Limpichaipanit, A.; Watcharapasorn, A.; Wirojanupatump, S.; Niranatlumpong, P.; Jiansirisomboon, S.

2011-12-01

Al2O3 /xZrO2 (where x = 0, 3, 13, and 20 wt.%) composite coatings were deposited onto mild steel substrates by atmospheric plasma spraying of mixed α-Al2O3 and nano-sized monoclinic-ZrO2 powders. Microstructural investigation showed that the coatings comprised well-separated Al2O3 and ZrO2 lamellae, pores, and partially molten particles. The coating comprised mainly of metastable γ-Al2O3 and tetragonal-ZrO2 with trace of original α-Al2O3 and monoclinic-ZrO2 phases. The effect of ZrO2 addition on the properties of coatings were investigated in terms of microhardness, fracture toughness, and wear behavior. It was found that ZrO2 improved the fracture toughness, reduced friction coefficient, and wear rate of the coatings.

The Surtsey Magma Series

PubMed Central

Ian Schipper, C.; Jakobsson, Sveinn P.; White, James D.L.; Michael Palin, J.; Bush-Marcinowski, Tim

2015-01-01

The volcanic island of Surtsey (Vestmannaeyjar, Iceland) is the product of a 3.5-year-long eruption that began in November 1963. Observations of magma-water interaction during pyroclastic episodes made Surtsey the type example of shallow-to-emergent phreatomagmatic eruptions. Here, in part to mark the 50th anniversary of this canonical eruption, we present previously unpublished major-element whole-rock compositions, and new major and trace-element compositions of sideromelane glasses in tephra collected by observers and retrieved from the 1979 drill core. Compositions became progressively more primitive as the eruption progressed, with abrupt changes corresponding to shifts between the eruption’s four edifices. Trace-element ratios indicate that the chemical variation is best explained by mixing of different proportions of depleted ridge-like basalt, with ponded, enriched alkalic basalt similar to that of Iceland’s Eastern Volcanic Zone; however, the systematic offset of Surtsey compositions to lower Nb/Zr than other Vestmannaeyjar lavas indicates that these mixing end members are as-yet poorly contained by compositions in the literature. As the southwestern-most volcano in the Vestmannaeyjar, the geochemistry of the Surtsey Magma Series exemplifies processes occurring within ephemeral magma bodies on the extreme leading edge of a propagating off-axis rift in the vicinity of the Iceland plume. PMID:26112644

Micron-Scale Correlations Among Ti, P, Ce, and Y in Hadean Jack Hills Zircons

NASA Astrophysics Data System (ADS)

Hofmann, A. E.; Cavosie, A. J.; Valley, J. W.; Eiler, J. M.

2007-12-01

Detrital zircons and the inclusions found therein are our only mineralogical constraints on geologic events that occurred on the Hadean Earth. These zircons are commonly small (ca. <100 μm in the longest dimension) and preserve micron to sub-micron chemical zonations indicative of a dynamic petrological history. Trace elements within zircon are of particular interest because concentrations and ratios of these elements can provide information regarding chemical and physical conditions during zircon growth. In this study, we analyzed Hadean-age detrital zircons from Archean metasediment in the Jack Hills (Australia) using the Caltech Microanalysis Center Cameca NanoSIMS 50L. Trace elements analyzed included Ti, P, Ce, and Y. Ti- thermometry [1,2,3] can potentially constrain growth and/or re-equilibration temperatures of zircons; P, Ce, and Y are known to enter the zircon lattice by the coupled xenotime-type substitution mechanism: (Y, REE)3+ + P5+ = Zr4+ + Si4+ [5]. The 89Y/28Si ratio was observed to correlate with, and was used as a proxy for, cathodoluminescence (CL) banding. Growth features manifested in CL (e.g., sector, oscillatory zoning) were observed in all zircons analyzed. CL zones vary from <1 μm to several microns in width; therefore, the NanoSIMS---with a beam diameter resolved to ca. 250 nm on the sample surface when operating with an O- primary beam---is uniquely suited for this scale of analysis. Regions displaying CL banding were imaged as 20 x 20 μm areas. All elements were normalized to 28Si; 49Ti/28Si ratios were converted to [Ti] via calibration based on analyses of synthetic, high-Ti zircons (provided by B. Watson) that were independently analyzed on Caltech's JEOL JXA-8200 electron microprobe. We observe three types of relationships between trace element distribution and CL banding in the zircons imaged: 1) strong positive correlations between CL banding, P, Ce, and Ti; 2) subtle positive correlations between CL banding, P, Ce, and Ti; 3) no correlation between minor/trace elements and CL banding. Positive correlations between CL banding, 3+ cations, and [Ti] have previously been reported by Holden et al. [4]. In this study, gradients at least as sharp as a factor of ~3 in [Ti] are observed between adjacent CL bands in the strongly correlated images. These images also have the highest absolute concentrations of trace elements and display both sector and oscillatory zoning in CL. The correlations observed may be due to: temperature-dependent equilibrium partitioning of all trace elements during rapid cycles in growth temperature; episodic diffusion-limited enrichment of incompatible trace elements in the boundary layer melt adjacent to growing crystals; and/or kinetically controlled, non- equilibrium crystal-melt partitioning caused by trace element enrichments in the boundary layer melt surrounding fast-growing grains (e.g., [6]). We will discriminate between these alternatives based on quantitative relationships between relative enrichments of [Ti] and other trace elements. [1]Watson, E.B. & Harrison, T.M. (2005) Science 308, 841-844. [2]Watson, E.B., Wark, D.A., & Thomas, J.B. (2006) CMP 151, 413-433. [3]Ferry, J.M. & Watson, E.B. (2007) CMP 154, 429-437. [4] Holden, P. et al. (2005) Eos Trans. AGU 86 (52) Fall Meet. Suppl., Abstract V41F-1539. [5] Speer, J.A. (1982) Zircon. In Rev. Min. 5 (ed. P.H. Ribbe), 67-112. [6] Watson, E.B. (2004) GCA 68, 1473-1488.

Elemental Geochemistry of Samples From Fault Segments of the San Andreas Fault Observatory at Depth (SAFOD) Drill Hole

NASA Astrophysics Data System (ADS)

Tourscher, S. N.; Schleicher, A. M.; van der Pluijm, B. A.; Warr, L. N.

2006-12-01

Elemental geochemistry 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 elements. Based on oxide data results, systematic differences in element 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 elements 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 element 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.

Geochemical characteristics of aluminum depleted and undepleted komatiites and HREE-enriched low-Ti tholeiites, western Abitibi greenstone belt: A heterogeneous mantle plume-convergent margin environment

NASA Astrophysics Data System (ADS)

Fan, J.; Kerrich, R.

1997-11-01

A compositionally diverse suite of komatiites, komatiitic basalts, and basalts coexist in the Tisdale volcanic assemblage of the late-Archean (˜2.7 Ga) Abitibi greenstone belt. The komatiites are characterized by a spectrum of REE patterns, from low total REE contents (9 ppm) and pronounced convex-up patterns to greater total REE (18 ppm) and approximately flat-distributions. Thorium and niobium are codepleted with LREE. Komatiites with the most convex-up patterns have low Al 2O 3 (4.7 wt%) contents and Al 2O 3/TiO 2(12) ratios; they are interpreted to be the Al-depleted variety of komatiite derived from a depleted mantle source. Those komatiites and komatiitic basalts with flatter REE patterns are characterized by greater Al 2O 3 (7.0 wt%) and near chondritic Al 2O 3/TiO 2 (20) ratios; they are interpreted to be Al-undepleted komatiites generated from trace element undepleted mantle. For the komatiites and komatiitic basalts collectively, Gd/Ybn ratios are negatively correlated with La/Smn, but positively with MgO and Ni. The spectrum of patterns is interpreted as mixing between Al, HREE, Y-depleted, and Sc-depleted komatiites and Al-undepleted komatiites in a heterogeneous mantle plume. Auminum-depleted komatiites are characterized by negative Zr and Hf anomalies, consistent with majorite garnet-liquid D's for HFSE and REEs, signifying melt segregation at depths of >400 km. Tisdale Al-undepleted komatiites and komatiitic basalts have small negative to zero Zr(Hf)/MREE fractionation, signifying melt segregation in or above the garnet stability field. Collectively, the komatiites have correlations of Zr/Zr∗ and Hf/Hf ∗ with Gd/Ybn, and hence the Zr(Hf)/MREE fractionations are unlikely to have stemmed from alteration or crustal contamination. Two types of basalts are present. Type I basalts are Mg-tholeiites with near flat REE and primitive mantle normalized patterns, compositionally similar to abundant Mg-tholeiites associated with both Al-undepleted and Al-depleted komatiites in the Abitibi belt. They have absolute concentrations and ratios of most moderately and highly compatible elements comparable to N- MORB (Zr ˜79 vs. 74, Y ˜30 vs. 28, and Zr/Y = 2.4-2.9 vs. 2.6 ), but are relatively less depleted in highly incompatible elements and lack positive Nb or P anomalies. Type II basalts are relatively aluminous (Al 2O 3 ˜ 16 wt%), with high Al 2O 3/TiO 2 (24-28) ratios. They are characterized by low Th, Nb, and LREE contents at eight to ten times chondrite, with slightly convex-up LREE patterns ( La/Smn = 0.86-0.99 ), but strongly fractionated and enriched HREEs, Y, and Sc, where Gd/Ybn = 0.50-0.55 and consistently positive Zr(Hf)/MREEs anomalies. These basalts are tentatively interpreted as low-Ti tholeiites formed in a convergent margin setting with second stage melting, induced by fluids and melts enriched in incompatible elements and Zr(Hf) relative to MREEs, of a mantle source depleted during first stage melting. They are analogous to the Phanerozoic low-Ti tholeiite - boninite association. Accordingly the Tisdale volcanic sequence records a plume-convergent margin interaction. New analyses of Al-undepleted komatiites from the classical locality at Pyke Hill in Munro Township confirm the presence of small positive anomalies of P, Zr, and Hf, with Zr/Hf ratios generally < 36. These signatures are similar in spinifex and cumulate zones signifying that they are unlikely to have resulted from alteration. The data were generated by INAA and ICP-MS using both HFHNO 3 dissolution and Na 2O 2 sinter. The lack of LREE enrichment with negative Nb, Ta, P, and Ti anomalies in any of the Tisdale or Munro komatiites confirms an intraoceanic setting for the volcanic stage of the Western Abitibi greenstone belt.

Trace Element Geochemistry of Basaltic Tephra in Maar Cores; Implications for Centre Correlation, Field Evolution, and Mantle Source Characteristics of the Auckland Volcanic Field, New Zealand

NASA Astrophysics Data System (ADS)

Hopkins, J. L.; Leonard, G.; Timm, C.; Wilson, C. J. N.; Neil, H.; Millet, M. A.

2014-12-01

Establishing volcanic hazard and risk management strategies hinges on a detailed understanding of the type, timing and tephra dispersal of past eruptions. In order to unravel the pyroclastic eruption history of a volcanic field, genetic links between the deposits and eruption source centre need to be established. The Auckland Volcanic Field (AVF; New Zealand) has been active for ca. 200 kyr and comprises ca. 53 individual centres covering an area of ca. 360km2. These centres show a range of sizes and eruptive styles from maar craters and tuff rings, to scoria cones and lava flows consistent with both phreatomagmatic and magmatic eruptions. Superimposition of the metropolitan area of Auckland (ca. 1.4 million inhabitants) on the volcanic field makes it critically important to assess the characteristics of the volcanic activity, on which to base assessment and management of the consequent hazards. Here we present a geochemical approach for correlating tephra deposits to their source centres. To acquire the most complete stratigraphic record of pyroclastic events, maar crater cores from different locations, covering various depths and thus ages across the field were selected. Magnetic susceptibility and x-ray density scanning of the cores was used to identify the basaltic tephra horizons, which were sampled and in-situ analysis of individual shards undertaken for major and trace elements using EPMA and LA-ICP-MS techniques, respectively. Our results show that tephra shard trace element ratios are comparable and complementary to the AVF whole rock database. The use of specific trace element ratios (e.g. Gd/Yb vs. Zr/Yb) allows us to fingerprint and cross correlate tephra horizons between cores and, when coupled with newly acquired 40Ar-39Ar age dating and eruption size estimates, correlate horizons to their source centres. This integrated style of study can provide valuable information to help volcanic hazard management and forecasting, and mitigation of related risks.

Petrogenesis of voluminous mid-Tertiary ignimbrites of the Sierra Madre Occidental, Chihuahua, Mexico

NASA Astrophysics Data System (ADS)

Cameron, Maryellen; Bagby, William C.; Cameron, Kenneth L.

1980-10-01

The mid-Tertiary ignimbrites of the Sierra Madre Occidental of western Mexico constitute the largest continuous rhyolitic province in the world. The rhyolites appear to represent part of a continental magmatic arc that was emplaced when an eastward-dipping subduction zone was located beneath western Mexico. In the Batopilas region of the northern Sierra Madre Occidental the mid-Tertiary Upper Volcanic sequence is composed predominantly of rhyolitic ignimbrites, but volumetrically minor lava flows as mafic as basaltic andesite are also present. The basaltic andesite to rhyolite series is calc-alkalic and contains ˜1% K2O at 60% SiO2. Trace element abundances of a typical ignimbrite with 73% SiO2 are Sr ˜ 225 ppm, Rb ˜130 ppm, Y ˜32 ppm, Th ˜12 ppm, Zr ˜200 ppm, and Nb ˜15 ppm. The entire series plots as coherent and continuous trends on variation diagrams involving major and trace elements, and the trends are distinct from those of geographicallyassociated rocks of other suites. We interpret these and other geochemical variations to indicate that the rocks are comagmatic. Mineral chemistry, Sr isotopic data, and REE modelling support this interpretation. Least squares calculations show that the major element variations are consistent with formation of the basaltic andesite to rhyolite series by crystal fractionation of observed phenocryst phases in approximate modal proportions. In addition, calculations modelling the behavior of Sr with the incompatible trace element Th favor a fractional crystallization origin over a crustal anatexis origin for the rock series. The fractionating minerals included plagioclase (> 50%), and lesser amounts of Fe-Ti oxides, pyroxenes, and/or hornblende. The voluminous ignimbrites represent no more than 20% of the original mass of a mantle-derived mafic parental magma.

Provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico unraveled by geochemical analysis

NASA Astrophysics Data System (ADS)

Armstrong-Altrin, John S.; Machain-Castillo, María Luisa; Rosales-Hoz, Leticia; Carranza-Edwards, Arturo; Sanchez-Cabeza, Joan-Albert; Ruíz-Fernández, Ana Carolina

2015-03-01

The aim of this work is to constrain the provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico (~1089-1785 m water depth). To achieve this, 10 piston sediment cores (~5-5.5 m long) were studied for mineralogy, major, trace and rare earth element geochemistry. Samples were analyzed at three core sections, i.e. upper (0-1 cm), middle (30-31 cm) and lower (~300-391 cm). The textural study reveals that the core sediments are characterized by silt and clay fractions. Radiocarbon dating of sediments for the cores at different levels indicated a maximum of ~28,000 year BP. Sediments were classified as shale. The chemical index of alteration (CIA) values for the upper, middle, and lower sections revealed moderate weathering in the source region. The index of chemical maturity (ICV) and SiO2/Al2O3 ratio indicated low compositional maturity for the core sediments. A statistically significant correlation observed between total rare earth elements (∑REE) versus Al2O3 and Zr indicated that REE are mainly housed in detrital minerals. The North American Shale Composite (NASC) normalized REE patterns, trace element concentrations such as Cr, Ni and V, and the comparison of REE concentrations in sediments and source rocks indicated that the study area received sediments from rocks intermediate between felsic and mafic composition. The enrichment factor (EF) results indicated that the Cd and Zn contents of the upper section sediments were influenced by an anthropogenic source. The trace element ratios and authigenic U content of the core sediments indicated the existence of an oxic depositional environment.

Microstructure and Phase Stability of Single Crystal NiAl Alloyed with Hf and Zr

NASA Technical Reports Server (NTRS)

Locci, I. E.; Dickerson, R. M.; Garg, A.; Noebe, R. D.; Whittenberger, J. D.; Nathal, M. V.; Darolia, R.

1996-01-01

Six near stoichiometric, NiAl single-crystal alloys, with 0.05-1.5 at.% of Hf and Zr additions plus Si impurities, were microstructurally analyzed in the as-cast, homogenized, and aged conditions. Hafnium-rich interdendritic regions, containing the Heusler phase (Ni2AlHf), were found in all the as-cast alloys containing Hf. Homogenization heat treatments partially reduced these interdendritic segregated regions. Transmission electron microscopy (TEM) observations of the as-cast and homogenized microstructures revealed the presence of a high density of fine Hf (or Zr) and Si-rich precipitates. These were identified as G-phase, Nil6X6Si7, or as an orthorhombic NiXSi phase, where X is Hf or Zr. Under these conditions the expected Heusler phase (beta') was almost completely absent. The Si responsible for the formation of the G and NiHfSi phases is the result of molten metal reacting with the Si-containing crucible used during the casting process. Varying the cooling rates after homogenization resulted in the refinement or complete suppression of the G and NiHfSi phases. In some of the alloys studied, long-term aging heat treatments resulted in the formation of Heusler precipitates, which were more stable at the aging temperature and coarsened at the expense of the G-phase. In other alloys, long-term aging resulted in the formation of the NiXSi phase. The stability of the Heusler or NiXSi phases can be traced to the reactive element (Hf or Zr) to silicon ratio. If the ratio is high, then the Heusler phase appears stable after long time aging. If the ratio is low, then the NiHfSi phase appears to be the stable phase.

Environmental assessment of potential toxic trace element contents in the inundated floodplain area of Tablas de Daimiel wetland (Spain).

PubMed

Jiménez-Ballesta, R; García-Navarro, F J; Bravo, S; Amorós, J A; Pérez-de-Los-Reyes, C; Mejías, M

2017-10-01

Contamination of aquatic systems with potentially toxic trace elements (PTEs) is a major problem throughout the world. The National Park Tablas de Daimiel (NPTD) is considered to make up one of the two most important wetlands in the Biosphere Reserve called "Wet Spot." Since PTEs are good indicator of the prevailing environmental conditions and possible contamination, soil samples collected from 43 sites were analyzed in order to investigate the levels and its distribution of these elements, in the inundated floodplain area of the NPTD wetland. In addition, some physicochemical parameters such as pH, electrical conductivity and organic matter were measured. The total concentrations of 32 trace elements were determined by X-ray fluorescence. The results show that there was accumulation of lead (Pb), tin (Sn), selenium (Se), antimony (Sb), copper (Cu), vanadium (V), nickel (Ni), zinc (Zn), arsenic (As), strontium (Sr) and zirconium (Zr)-in some cases at high concentrations. The interpolated maps showed that the distributions of some of these elements and in some cases the trend in spatial variability are pronounced and decrease from the inlet to the outlet. The values for some elements are higher than the reference values, which is consistent with contamination (some values are higher by a factor of more than 10 compared to the reference). In the case of iodine (I), the levels at some sample points are significantly more than ten times the reference; Se appears in the range from 1.0 to 9.8 mg/kg, with an average value of 3.1 mg/kg, and these can be considered as seleniferous soils. The concentrations found are consistent with the introduction in the wetland of pollution by human activities, such as agricultural non-point sources, uncontrolled fertilization over many years, treatment with urban wastewater and other possible sources.

Carbonatite magmatism in northeast India

NASA Astrophysics Data System (ADS)

Kumar, D.; Mamallan, R.; Dwivedy, K. K.

The Shillong Plateau of northeast India is identified as an alkaline province in view of the development of several carbonatite complexes e.g. the Sung Valley (Jaintia Hills), Jasra (Karbi-Anglong), Samchampi and Barpung (Mikir Hills) and lamprophyre dyke swarms (Swangkre, Garo-Khasi Hills). On the basis of limited KAr data, magmatic activity appears to have taken place over a protracted period, ranging from the Late Jurassic to the Early Cretaceous. The carbonatite complexes of the Shillong Plateau share several common traits: they are emplaced along rift zones, either within Archaean gneisses or Proterozoic metasediments and granites, and exhibit enrichment in the light rare-earth elements, U, Th, Nb, Zr, Ti, K and Na. The enrichment in incompatible trace elements can best be accounted for if the parental magmas were of alkali basaltic type (e.g. mela-nephelinite or carbonate-rich alkali picrite).

A high-pyrite semianthracite of Late Permian age in the Songzao Coalfield, southwestern China: Mineralogical and geochemical relations with underlying mafic tuffs

USGS Publications Warehouse

Dai, S.; Wang, X.; Chen, W.; Li, D.; Chou, C.-L.; Zhou, Y.; Zhu, Chen; Li, H.; Zhu, Xudong; Xing, Y.; Zhang, W.; Zou, J.

2010-01-01

The No. 12 Coal (Late Permian) in the Songzao Coalfield, Chongqing, southwestern China, is characteristically high in pyrite and some trace elements. It is uniquely deposited directly above mafic tuff beds. Samples of coal and tuffs have been studied for their mineralogy and geochemistry using inductively coupled plasma-mass spectrometry, X-ray fluorescence, plasma low-temperature ashing plus powder X-ray diffraction, and scanning electron microscopy equipped with energy-dispersive X-ray analysis.The results show that the minerals of the No. 12 Coal are mainly composed of pyrite, clay minerals (kaolinite, chamosite, and illite), ankerite, calcite, and trace amounts of quartz and boehmite. Kaolinite and boehmite were mainly derived from sediment source region of mafic tuffs. Chamosite was formed by the reaction of kaolinite with Fe-Mg-rich fluids during early diagenesis. The high pyrite (Sp,d=8.83%) in the coal was related to marine transgression over peat deposits and abundant Fe derived from the underlying mafic tuff bed. Ankerite and calcite were precipitated from epigenetic fluids.Chemical compositions of incompatible elements indicate that the tuffs were derived from enriched mantle and the source magmas had an alkali-basalt character. Compared to other coals from the Songzao Coalfield and common Chinese coals, the No. 12 Coal has a lower SiO2/Al2O3 (1.13) but a higher Al2O3/Na2O (80.1) value and is significantly enriched in trace elements including Sc (13.5??g/g), V (121??g/g), Cr (33.6??g/g), Co (27.2??g/g), Ni (83.5??g/g), Cu (48.5??g/g), Ga (17.3??g/g), Y (68.3??g/g), Zr (444??g/g), Nb (23.8??g/g), and REE (392??g/g on average). Above mineralogical compositions, as well as similar ratios of selected elements (e.g., SiO2/Al2O3 and Al2O3/Na2O) and similar distribution patterns of incompatible elements (e.g., the mantle-normalized diagram for incompatible elements and chondrite-normalized diagram for rare earth elements) of coal and tuff, indicated that enriched trace elements above were largely derived from mafic tuffs, in addition to a minor amount from the Kandian Oldland. ?? 2010 Elsevier B.V.

Enhanced thermal stability of Cu alloy films by strong interaction between Ni and Zr (or Fe)

NASA Astrophysics Data System (ADS)

Zheng, Yuehong; Li, Xiaona; Cheng, Xiaotian; Li, Zhuming; Liu, Yubo; Dong, Chuang

2018-04-01

Low resistivity, phase stability and nonreactivity with surrounding dielectrics are the key to the application of Cu to ultra-large-scale integrated circuits. Here, a stable solid solution cluster model was introduced to design the composition of barrierless Cu-Ni-Zr (or Fe) seed layers. The third elements Fe and Zr were dissolved into Cu via a second element Ni, which is soluble in both Cu and Zr (or Fe). The films were prepared by magnetron sputtering on the single-crystal p-Si (1 0 0) wafers. Since the diffusion characteristics of the alloying elements are different, the effects of the strong interaction between Ni and Zr (or Fe) on the film’s stability and resistivity were studied. The results showed that a proper addition of Zr-Ni (Zr/Ni  ⩽  0.6/12) into Cu could form a large negative lattice distortion, which inhibits Cu-Si interdiffusion and enhances the stability of Cu film. When Fe-Ni was co-added into Cu, the lattice distortion of Cu reached a lower value, 0.0029 Å  ⩽  |Δa|  ⩽  0.0046 Å, and the films showed poor stability. Therefore, when the model is applied to the composition design of the films, the strong interaction between the elements and the addition ratio should be taken into consideration.

Characterisation of a natural quartz crystal as a reference material for microanalytical determination of Ti, Al, Li, Fe, Mn, Ga and Ge

USGS Publications Warehouse

Audetat, Andreas; Garbe-Schonberg, Dieter; Kronz, Andreas; Pettke, Thomas; Rusk, Brian G.; Donovan, John J.; Lowers, Heather

2015-01-01

A natural smoky quartz crystal from Shandong province, China, was characterised by laser ablation ICP-MS, electron probe microanalysis (EPMA) and solution ICP-MS to determine the concentration of twenty-four trace and ultra trace elements. Our main focus was on Ti quantification because of the increased use of this element for titanium-in-quartz (TitaniQ) thermobarometry. Pieces of a uniform growth zone of 9 mm thickness within the quartz crystal were analysed in four different LA-ICP-MS laboratories, three EPMA laboratories and one solution-ICP-MS laboratory. The results reveal reproducible concentrations of Ti (57 ± 4 μg g-1), Al (154 ± 15 μg g-1), Li (30 ± 2 μg g-1), Fe (2.2 ± 0.3 μg g-1), Mn (0.34 ± 0.04 μg g-1), Ge (1.7 ± 0.2 μg g-1) and Ga (0.020 ± 0.002 μg g-1) and detectable, but less reproducible, concentrations of Be, B, Na, Cu, Zr, Sn and Pb. Concentrations of K, Ca, Sr, Mo, Ag, Sb, Ba and Au were below the limits of detection of all three techniques. The uncertainties on the average concentration determinations by multiple techniques and laboratories for Ti, Al, Li, Fe, Mn, Ga and Ge are low; hence, this quartz can serve as a reference material or a secondary reference material for microanalytical applications involving the quantification of trace elements in quartz.

A tale of phenocrysts: trace element contents of boninites and forearc basalts from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Chapman, T.; Clarke, G. L.; Reagan, M. K.; Sakuyama, T.; Godard, M.; Shervais, J. W.; Prytulak, J.; Shimizu, K.; Nelson, W. R.; Heaton, D. E.; Whattam, S. A.; Li, H.; Pearce, J. A.

2016-12-01

The Izu-Bonin Mariana (IBM) forearc represents an ideal location to study the dynamics of subduction initiation and to reveal the volcanic sequences appropriate to assess ophiolite origins. The volcanic stratigraphy recovered on Expedition 352 illustrates an abrupt shift from forearc basalt (FAB) to boninite magmatism, with limited transitional rock types, as observed from submersible and previous drill work in the Izu-Bonin and Mariana sections. The transition represents a change from decompression melting to fluxed melting of the mantle wedge. The volcanic stratigraphy has several distinct boninite chemical evolution trends (basaltic boninite, low- and high-silica boninite). Mineral assemblages and phenocryst trace element compositions vary throughout the volcanic sequence providing an opportunity to explore more completely boninite and FAB transitions and petrogenesis. FABs are characterised by early plagioclase crystallization and HREE enriched clinopyroxene with high Ti contents. Basaltic boninite and some low-silica boninite lavas have overlapping REE concentrations consistent with early plagioclase growth preceded by clinopyroxene. In contrast, textures and HREE depleted concentrations of clinopyroxene in high-silica boninite imply late plagioclase growth relative to olivine and orthopyroxene. Variations in mineral compositions and paragenesis in boninites reflect changes in magma compositions and a progressive depletion of mantle sources over time. This is illustrated via key incompatible and compatible trace element ratios and concentrations (e.g. Zr/Ti & V or Cr). The transition from FAB to low-Si boninite was subtle in terms of mineral modes, but was more evident in terms of the phase and lava compositions.

Laser-Assisted Atom Probe Tomography of Deformed Minerals: A Zircon Case Study.

PubMed

La Fontaine, Alexandre; Piazolo, Sandra; Trimby, Patrick; Yang, Limei; Cairney, Julie M

2017-04-01

The application of atom probe tomography to the study of minerals is a rapidly growing area. Picosecond-pulsed, ultraviolet laser (UV-355 nm) assisted atom probe tomography has been used to analyze trace element mobility within dislocations and low-angle boundaries in plastically deformed specimens of the nonconductive mineral zircon (ZrSiO4), a key material to date the earth's geological events. Here we discuss important experimental aspects inherent in the atom probe tomography investigation of this important mineral, providing insights into the challenges in atom probe tomography characterization of minerals as a whole. We studied the influence of atom probe tomography analysis parameters on features of the mass spectra, such as the thermal tail, as well as the overall data quality. Three zircon samples with different uranium and lead content were analyzed, and particular attention was paid to ion identification in the mass spectra and detection limits of the key trace elements, lead and uranium. We also discuss the correlative use of electron backscattered diffraction in a scanning electron microscope to map the deformation in the zircon grains, and the combined use of transmission Kikuchi diffraction and focused ion beam sample preparation to assist preparation of the final atom probe tip.

Dissolved organic carbon and major and trace elements in peat porewater of sporadic, discontinuous, and continuous permafrost zones of western Siberia

NASA Astrophysics Data System (ADS)

Raudina, Tatiana V.; Loiko, Sergey V.; Lim, Artyom G.; Krickov, Ivan V.; Shirokova, Liudmila S.; Istigechev, Georgy I.; Kuzmina, Daria M.; Kulizhsky, Sergey P.; Vorobyev, Sergey N.; Pokrovsky, Oleg S.

2017-07-01

Mobilization of dissolved organic carbon (DOC) and related trace elements (TEs) from the frozen peat to surface waters in the permafrost zone is expected to enhance under ongoing permafrost thaw and active layer thickness (ALT) deepening in high-latitude regions. The interstitial soil solutions are efficient tracers of ongoing bio-geochemical processes in the critical zone and can help to decipher the intensity of carbon and metals migration from the soil to the rivers and further to the ocean. To this end, we collected, across a 640 km latitudinal transect of the sporadic to continuous permafrost zone of western Siberia peatlands, soil porewaters from 30 cm depth using suction cups and we analyzed DOC, dissolved inorganic carbon (DIC), and 40 major elements and TEs in 0.45 µm filtered fraction of 80 soil porewaters. Despite an expected decrease in the intensity of DOC and TE mobilization from the soil and vegetation litter to the interstitial fluids with the increase in the permafrost coverage and a decrease in the annual temperature and ALT, the DOC and many major and trace elements did not exhibit any distinct decrease in concentration along the latitudinal transect from 62.2 to 67.4° N. The DOC demonstrated a maximum of concentration at 66° N, on the border of the discontinuous/continuous permafrost zone, whereas the DOC concentration in peat soil solutions from the continuous permafrost zone was equal to or higher than that in the sporadic/discontinuous permafrost zone. Moreover, a number of major (Ca, Mg) and trace (Al, Ti, Sr, Ga, rare earth elements (REEs), Zr, Hf, Th) elements exhibited an increasing, not decreasing, northward concentration trend. We hypothesize that the effects of temperature and thickness of the ALT are of secondary importance relative to the leaching capacity of peat, which is in turn controlled by the water saturation of the peat core. The water residence time in peat pores also plays a role in enriching the fluids in some elements: the DOC, V, Cu, Pb, REEs, and Th were a factor of 1.5 to 2.0 higher in mounds relative to hollows. As such, it is possible that the time of reaction between the peat and downward infiltrating waters essentially controls the degree of peat porewater enrichments in DOC and other solutes. A 2° northward shift in the position of the permafrost boundaries may bring about a factor of 1.3 ± 0.2 decrease in Ca, Mg, Sr, Al, Fe, Ti, Mn, Ni, Co, V, Zr, Hf, Th, and REE porewater concentration in continuous and discontinuous permafrost zones, and a possible decrease in DOC, specific ultraviolet absorbency (SUVA), Ca, Mg, Fe, and Sr will not exceed 20 % of their current values. The projected increase in ALT and vegetation density, northward migration of the permafrost boundary, or the change of hydrological regime is unlikely to modify chemical composition of peat porewater fluids larger than their natural variations within different micro-landscapes, i.e., within a factor of 2. The decrease in DOC and metal delivery to small rivers and lakes by peat soil leachate may also decrease the overall export of dissolved components from the continuous permafrost zone to the Arctic Ocean. This challenges the current paradigm on the increase in DOC export from the land to the ocean under climate warming in high latitudes.

Electrochemical studies on zirconium and its biocompatible alloys Ti-50Zr at.% and Zr-2.5Nb wt.% in simulated physiologic media.

PubMed

Oliveira, Nilson T C; Biaggio, Sonia R; Rocha-Filho, Romeu C; Bocchi, Nerilso

2005-09-01

Different electrochemical studies were carried out for Zr and its biocompatible alloys Ti-50Zr at.% and Zr-2.5Nb wt.% in solutions simulating physiologic media, Ringer and PBS (phosphate buffered saline) solutions. The results from rest-potential measurements showed that the three materials are spontaneously passivated in both solutions and that the Ti-50Zr alloy has the greatest tendency for spontaneous oxide formation. Some corrosion parameters (such as the pitting and repassivation potentials) were obtained via cyclic voltammetry in both solutions, revealing that the Ti-50Zr has the best corrosion protection while Zr has the worst. On the other hand, the pre-anodization (up to 8 V vs. SCE) of the alloys in a 0.15 mol/L Na2SO4 solution led to a significant improvement in their protection against pitting corrosion when exposed to the Ringer solution. Elemental analyses by EDX showed that during pitting corrosion, there is no preferential corrosion of any of the alloying elements (Zr, Ti, Nb). Copyright (c) 2005 Wiley Periodicals, Inc.

Trace-element patterns of fibrous and monocrystalline diamonds: Insights into mantle fluids

NASA Astrophysics Data System (ADS)

Rege, S.; Griffin, W. L.; Pearson, N. J.; Araujo, D.; Zedgenizov, D.; O'Reilly, S. Y.

2010-08-01

During their growth diamonds may trap micron-scale inclusions of the fluids from which they grew, and these "time capsules" provide insights into the metasomatic processes that have modified the subcontinental lithospheric mantle. LAM-ICPMS analysis of trace elements in > 500 fibrous and monocrystalline diamonds worldwide has been used to understand the nature of these fluids. Analyses of fibrous diamonds define two general types of pattern, a "fibrous-high" (FH) one with high contents of LREE, Ba and K, and a "fibrous-low" (FL) pattern characterized by depletion in LREE/MREE, Ba and K, negative anomalies in Sr and Y, and subchondritic Zr/Hf and Nb/Ta. Both types may be found in fibrous diamonds from single deposits, and in three Yakutian pipes some diamonds show abrupt transitions from inclusion-rich cores with FH patterns to clearer rims with FL patterns. Most monocrystalline diamonds show FL-type patterns, but some have patterns that resemble those of FH fibrous diamonds. Peridotitic and eclogitic monocrystalline diamonds may show either patterns with relatively flat REE, or patterns with more strongly depleted LREE. Kimberlites that contain peridotitic diamonds with "high" patterns also contain eclogitic diamonds with "high" patterns. Strong similarities in the patterns of these two groups of diamonds may suggest high fluid/rock ratios. Many diamonds of the "superdeep" paragenesis have trace-element patterns similar to those of other monocrystalline diamonds. This may be evidence that the trace-element compositions of deep-seated fluids are generally similar to those that form diamonds in the subcontinental lithospheric mantle. The element fractionations observed between the FH and FL patterns are consistent with the immiscible separation of a silicic fluid from a carbonatite-silicate fluid, leaving a residual carbonatitic fluid strongly enriched in LREE, Ba and alkalies. This model would suggest that most monocrystalline diamonds crystallized from the more silicic fraction. Comparison with studies of single fluid inclusions in fibrous diamonds suggests that the FH patterns reflect trapped inclusions of high-Mg and low-Mg carbonatitic high-density fluids. In terms of the rock-forming elements, the fluids that precipitated the rims of some fibrous diamonds (FL pattern) and most monocrystalline diamonds are broadly similar to some hydro-silicic high-density fluids found in fibrous diamonds. However, there are still significant differences between the trace-element patterns of most monocrystalline diamonds and known high-density fluids, and further research is required to understand the formation and growth of these diamonds.

Coal fly ash-slag-based geopolymers: microstructure and metal leaching.

PubMed

Izquierdo, Maria; Querol, Xavier; Davidovits, Joseph; Antenucci, Diano; Nugteren, Henk; Fernández-Pereira, Constantino

2009-07-15

This study deals with the use of fly ash as a starting material for geopolymeric matrices. The leachable concentrations of geopolymers were compared with those of the starting fly ash to evaluate the retention of potentially harmful elements within the geopolymer matrix. Geopolymer matrices give rise to a leaching scenario characterised by a highly alkaline environment, which inhibits the leaching of heavy metals but may enhance the mobilization of certain oxyanionic species. Thus, fly ash-based geopolymers were found to immobilize a number of trace pollutants such as Be, Bi, Cd, Co, Cr, Cu, Nb, Ni, Pb, Sn, Th, U, Y, Zr and rare earth elements. However, the leachable levels of elements occurring in their oxyanionic form such as As, B, Mo, Se, V and W were increased after geopolymerization. This suggests that an optimal dosage, synthesis and curing conditions are essential in order to obtain a long-term stable final product that ensures an efficient physical encapsulation.

Preparation of novel alginate based anion exchanger from Ulva japonica and its application for the removal of trace concentrations of fluoride from water.

PubMed

Paudyal, Hari; Pangeni, Bimala; Inoue, Katsutoshi; Kawakita, Hidetaka; Ohto, Keisuke; Ghimire, Kedar Nath; Alam, Shafiq

2013-11-01

A green seaweed, Ulva japonica, was modified by loading multivalent metal ions such as Zr(IV) and La(III) after CaCl2 cross-linking to produce metal loaded cross-linked seaweed (M-CSW) adsorbents, which were characterized by elemental analysis, functional groups identification, and metal content determination. Maximum sorption potential for fluoride was drastically increased after La(III) and Zr(IV) loading, which were evaluated as 0.58 and 0.95 mmol/g, respectively. Loaded fluoride was quantitatively desorbed by using dilute alkaline solution for its regeneration. Mechanism of fluoride adsorption was inferred in terms of ligand exchange reaction between hydroxyl ion on co-ordination sphere of the loaded metal ions of M-CSW and fluoride ion in aqueous solution. Application of M-CSW for the treatment of actual waste plating solution exhibited successful removal of fluoride to clear the effluent and environmental standards in Japan, suggesting high possibility of its application for the treatment of fluoride rich waste water. Copyright © 2013 Elsevier Ltd. All rights reserved.

Alkalic Lavas From Nintoku Seamount, Emperor Seamount Chain: Geochemistry of Hawaiian Post-Shield Magmatism at 55 Ma

NASA Astrophysics Data System (ADS)

Shafer, J. T.; Gudding, J. A.; Neal, C. R.; Regelous, M.

2002-12-01

Ocean Drilling Project (ODP) Leg 197, Site 1205 penetrated 283 m into the volcanic basement of Nintoku Seamount, which is located roughly half-way along the Emperor Seamount Chain and has been dated at approximately 55-56 Ma by 40Ar-39Ar (R. Duncan, pers. comm., 2002). 25 subaerially-erupted lava flows, together with interflow sediments and soil horizons, were recovered. We report major and trace element compositions of 33 rock samples spanning the entire lava sequence and hawaiite clasts from a conglomerate immediately overlying the igneous basement. The volcanic rocks at Site 1205 are dominantly alkalic to intermediate basalts with between 5 and 11% MgO, with the degree of alkalinity generally increasing up-section, and the eruption rate (inferred from the thickness and abundance of interflow soils) appears to have decreased with time. Two flows in the lower half of the hole are tholeiitic and divide the section into two different alkalic basalt series. One of these flows contains accumulated olivine crystals and has a picritic composition. The upper alkalic series generally becomes enriched in the highly incompatible elements (ITEs) up-section from the tholeiitic units and is overlain by a conglomerate that contains cobbles of hawaiite that are highly enriched in ITEs. Normalized patterns are subparallel to those of the upper series of alkalic basalts, suggesting the hawaiites may be related by fractional crystallization. The lower alkalic series contains basalts that are among the most ITE enriched of the recovered basement sequence, but does not show the same variations as the upper series. The petrology of the Site 1205 lavas is very similar to those of lavas erupted during the later evolutionary stages of young volcanoes from the Hawaiian Islands and were probably all erupted during the post-shield alkalic stage; at Nintoku the post-shield alkalic cap appears to be relatively thick (at least 300m) compared to many other Hawaiian volcanoes, but is similar to that of Mauna Kea and Haleakala. Fractionation of the observed phenocryst phases (olivine and plagioclase) was responsible for much of the compositional variation within the Nintoku basaltic lavas, and the low Sc concentrations of the hawaiites show that they have also fractionated clinopyroxene. However, variations in incompatible trace element ratios indicate that the lavas cannot all be related by crystal fractionation from a single parental magma. Nintoku lavas exhibit broad similarities in major and trace element compositions of post-shield lavas from the Hawaiian Islands. For example, La/Yb ratios of the 1205 basalts (5-13) are similar to those of alkali basalts from Mauna Kea (5-12), but lower than those from Haleakala (12-17). However, distinct differences also occur. Nintoku lavas have relatively low Zr concentrations, so that they plot below the main Hawaiian array on a Zr/Nb-La/Yb diagram. Previous studies have show that lavas from the oldest Emperor Seamounts have relatively depleted incompatible trace element compositions; our data suggest that by 56 Ma, lavas erupted above the Hawaiian Hotspot were essentially similar to young (<5 Ma) lavas from the Hawaiian Islands.

Quantification of chemical elements in blood of patients affected by multiple sclerosis.

PubMed

Forte, Giovanni; Visconti, Andrea; Santucci, Simone; Ghazaryan, Anna; Figà-Talamanca, Lorenzo; Cannoni, Stefania; Bocca, Beatrice; Pino, Anna; Violante, Nicola; Alimonti, Alessandro; Salvetti, Marco; Ristori, Giovanni

2005-01-01

Although some studies suggested a link between exposure to trace elements and development of multiple sclerosis (MS), clear information on their role in the aetiology of MS is still lacking. In this study the concentrations of Al, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Sb, Si, Sn, Sr, Tl, V, W, Zn and Zr were determined in the blood of 60 patients with MS and 60 controls. Quantifications were performed by inductively coupled plasma (ICP) atomic emission spectrometry and sector field ICP mass spectrometry. When the two groups were compared, an increased level of Co, Cu and Ni and a decrement of Be, Fe, Hg, Mg, Mo, Pb and Zn in blood of patients were observed. In addition, the discriminant analysis pointed out that Cu, Be, Hg, Co and Mo were able to discriminate between MS patients and controls (92.5% of cases correctly classified).

Solution Treatment Effect on Tensile, Impact and Fracture Behaviour of Trace Zr Added Al-12Si-1Mg-1Cu Piston Alloy

NASA Astrophysics Data System (ADS)

Kaiser, Md. Salim

2018-04-01

The effects of T6 solution treatment on tensile, impact and fracture properties of cast Al-12Si-1Mg-1Cu piston alloys with trace of zirconium were investigated. Cast alloys were given precipitation strengthening treatment having a sequence of homogenizing, solutionizing, quenching and ageing. Both cast and solutionized samples are isochronally aged for 90 min at different temperatures up to 300 °C. Tensile and impact properties of the differently processed alloys have been studied to understand the precipitation strengthening of the alloys. Fractograpy of the alloys were observed to understand the mode of fracture. It is observed that the improvement in tensile properties in the aged alloys through heat treatment is mainly attributed to the formation of the Al2Cu and Mg2Si precipitates within the Al matrix. Solution treatment improves the tensile strength for the reason that during solution treatment some alloying elements are re-dissolved to produce a solute-rich solid solution. Impact energy decreases with ageing temperature due to formation of GP zones, β' and β precipitates. The fractography shows large and small dimple structure and broken or cracked primary Si, particles. Microstructure study of alloys revealed that the solution treatment improved distribution of silicon grains. The addition of Zr produces an improvement in the tensile properties as a result of its grain refining action and grain coarsening resistance in the matrix at a higher temperature.

THE DETERMINATION OF TRACES OF BORON IN ZIRCONIUM METAL AND ZIRCONIUM ALLOYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, M.R.; Metcalfe, J.

1962-01-01

A general procedure is given for the determination of B, down to 0.2 ppm, in Zr and Zr alloys. Separation of the B is not necessary, the B-curcumin complex being formed directly in an aliquot of the metal sulfate solution. An interference effect has been noted when analyzing Zr alloys containing Sn. The interference is caused by an insoluble compound of curcumin which separates and has similar properties to the B-curcumin complex. This source of interference is, however, readily eliminated during the procedure for the determination of B. The procedure has been applied to the determination of B in puremore » Zr, zr--0.5% Cu-- 0.5% MO, and Zr--1.5% Sn--0.1% Fe--0.1% Cr--0.05% Ni alloys. Results are comparable with those obtained by methods requiring the separation of the B as methyl borate. (auth)« less

The role of liquid-liquid immiscibility and crystal fractionation in the genesis of carbonatite magmas: insights from Kerimasi melt inclusions

NASA Astrophysics Data System (ADS)

Guzmics, Tibor; Zajacz, Zoltán; Mitchell, Roger H.; Szabó, Csaba; Wälle, Markus

2015-02-01

We have reconstructed the compositional evolution of the silicate and carbonate melt, and various crystalline phases in the subvolcanic reservoir of Kerimasi Volcano in the East African Rift. Trace element concentrations of silicate and carbonate melt inclusions trapped in nepheline, apatite and magnetite from plutonic afrikandite (clinopyroxene-nepheline-perovskite-magnetite-melilite rock) and calciocarbonatite (calcite-apatite-magnetite-perovskite-monticellite-phlogopite rock) show that liquid immiscibility occurred during the generation of carbonatite magmas from a CO2-rich melilite-nephelinite magma formed at relatively high temperatures (1,100 °C). This carbonatite magma is notably more calcic and less alkaline than that occurring at Oldoinyo Lengai. The CaO-rich (32-41 wt%) nature and alkali-"poor" (at least 7-10 wt% Na2O + K2O) nature of these high-temperature (>1,000 °C) carbonate melts result from strong partitioning of Ca (relative to Mg, Fe and Mn) in the immiscible carbonate and the CaO-rich nature (12-17 wt%) of its silicate parent (e.g., melilite-nephelinite). Evolution of the Kerimasi carbonate magma can result in the formation of natrocarbonatite melts with similar composition to those of Oldoinyo Lengai, but with pronounced depletion in REE and HFSE elements. We suggest that this compositional difference results from the different initial parental magmas, e.g., melilite-nephelinite at Kerimasi and a nephelinite at Oldoinyo Lengai. The difference in parental magma composition led to a significant difference in the fractionating mineral phase assemblage and the element partitioning systematics upon silicate-carbonate melt immiscibility. LA-ICP-MS analysis of coeval silicate and carbonate melt inclusions provides an opportunity to infer carbonate melt/silicate melt partition coefficients for a wide range of elements. These data show that Li, Na, Pb, Ca, Sr, Ba, B, all REE (except Sc), U, V, Nb, Ta, P, Mo, W and S are partitioned into the carbonate melt, whereas Mg, Mn, Fe, Co, Cu, Zn, Al, Sc, Ti, Hf and Zr are partitioned into the silicate melt. Potassium and Rb show no preferential partitioning. Kerimasi melt inclusions show that the immiscible calcic carbonate melt is strongly enriched in Sr, Ba, Pb, LREE, P, W, Mo and S relative to other trace elements. Comparison of our data with experimental results indicates that preferential partitioning of oxidized sulfur (as SO4 2-), Ca and P (as PO4 3-) into the carbonate melt may promote the partitioning of Nb, Ta, Pb and all REE, excluding Sc, into this phase. Therefore, it is suggested that P and S enrichment in calcic carbonate magmas promotes the genesis of REE-rich carbonatites by liquid immiscibility. Our study shows that changes in the partition coefficients of elements between minerals and the coexisting melts along the liquid line of descent are rather significant at Kerimasi. This is why, in addition to the REE, Nb, Ta and Zr are also enriched in Kerimasi calciocarbonatites. We consider significant amounts of apatite and perovskite precipitated from melilite-nephelinite-derived carbonate melt as igneous minerals can have high LREE, Nb and Zr contents relative to other carbonatite minerals.

Influence of minor combined addition of Cr and Pr on microstructure, mechanical properties and corrosion behaviors of an ultrahigh strength Al-Zn-Mg-Cu-Zr alloy.

PubMed

Wang, Ming; Huang, Lanping; Chen, Kanghua; Liu, Wensheng

2018-01-01

This work focuses on controlling grain boundary structure in an ultra-high strength Al-8.6Zn-2.5Mg-2.2Cu-0.16Zr (wt.%) alloy by the combined addition of trace Cr (0.1wt.%) and Pr (0.14wt.%), and evaluating mechanical properties and localized corrosion behaviors of the alloy in the peak aged condition. The introduction of trace Cr and Pr leads to the formation of nanoscale Cr, Pr-containing Al 3 Zr and Zr-containing PrCr 2 Al 20 dispersoids which can obviously inhibit the recrystallization and sub-grain growth of the super-high strength Al-Zn-Mg-Cu alloys, and retain the deformation-recovery microstructure dominated by low-angle grain boundaries. The nearly ellipsoidal dispersoids with a size of 10-35nm are discretely distributed and precipitate free zones are hardly formed in low-angle grain boundaries. This new alloy composition exhibits better combined properties, higher resistance to stress corrosion, exfoliation corrosion and inter-granular corrosion with the undamaged strength, ductility and fracture toughness. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of sediment recycling on the trace element composition of primitive arc lavas

NASA Astrophysics Data System (ADS)

Collinet, M.; Jagoutz, O. E.

2017-12-01

Primitive calc-alkaline lavas from continental arcs are, on average, enriched in incompatible elements compared to those from intra-oceanic arcs. This relative enrichment is observed in different groups of trace elements: LILE (e.g. K, Rb), LREE to MREE (La-Dy) and HFSE (e.g.Zr, Nb) and is thought to result from (1) a transfer of material from the subducting slab to the mantle wedge at higher temperature than in intra-oceanic margins and/or (2) lower average degrees of melting in the mantle wedge, as a consequence of thicker overlying crusts and higher average pressures of melting. In addition to thicker overlying crusts and generally higher slab temperatures, continental margins are characterized by larger volumes of rock exposed above sea level and enhanced erosion rates compared to intra-oceanic arcs. As several geochemical signatures of arc lavas attest to the importance of sediment recycling in subduction zones, we explore the possibility that the high concentrations of incompatible elements in primitive lavas from continental arcs directly reflect a larger input of sediment to the subduction system. Previous efforts to quantify the sediment flux to oceanic trenches focused on the thickness of pelagic and hemipelagic sediments on top of the plate entering the subduction zone (Plank and Langmuir, 1993, Nature). These estimates primarily relied on the sediment layer drilled outboard from the subduction system and likely underestimate the volume of sediment derived from the arc itself. Accordingly, we find that such estimates of sediment flux do not correlate with the concentration of incompatible elements in primitive arc lavas. To account for regional contributions of coarser detrital sediments, usually delivered to oceanic trenches by turbidity currents, we apply to arc segments a model that quantifies the sediment load of rivers based on the average relief, area, temperature and runoff of their respective drainage areas (Syvitski et al., 2003, Sediment. Geol.). Our new estimates of sediment fluxes correlate positively with incompatible element concentrations in primitive arc lavas. We conclude that a large fraction of the local terrigenous sediments is subducted and contributes to the observed dichotomy in the trace element budget between primitive lavas from continental and oceanic margins.

Improvement of glass-forming ability and phase separation in Cu Ti-rich

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, E S; Chang, H J; Kim, D H

2010-01-01

Present study reports improvement of glass-forming ability (GFA) and phase separation in Cu Ti-rich Cu Ti Zr Ni Si bulk metallic glasses (BMGs) by tailoring the constituent elements. The MA of metalloid element, Sn having relatively large negative enthalpy of mixing can lead to improve GFA (up to 8mm in diameter) as well as thermal stability (up toTx = 48K) by optimizing the substitution element. And the addition of elements having relatively large positive enthalpy of mixing (partial substitution of Zr or Ti with Y) can lead to the liquid state phase separation in Cu Ti Sn Zr Ni Simore » BMG, although the addition lead to drastic deterioration of the GFA.« less

Trace elements quantified by the APXS on Mars

NASA Astrophysics Data System (ADS)

Gellert, R.; Berger, J. A.; Boyd, N.; O'Connell-Cooper, C.; Desouza, E.; Thompson, L. M.; VanBommel, S.; Yen, A.

2017-12-01

The APXS accurately quantifies many trace elements within the dime-sized sample: Ni, Cu, Zn, Ga, Ge, Pb, Br, Se, As, and Y with 20 ppm detection limit (DL) and Rb, Sr, Zr, Co, Cr, and Mn with 200 ppm DL. Together with the major and minor elements, this gives important constraints for a variety of formation processes of the investigated soils, floats or extensive bedrock on Mars. The global soil, found at all rover landing sites, was used to define an average Mars value for Ni, Zn, Cr and Mn, with a consistent value of Fe/Mn 50 for soils and igneous rocks. All other APXS trace elements are below DL. Strong enrichments or depletions can both give evidence for the formation processes and link together groups of rocks and indicate their common diagenetic origin. Felsic rocks at Gale and Gusev have Cr, Ni and Zn far below soil, indicating their likely igneous origin. Further, similarly low values are found in elevated silica samples in the Murray Fm. at Gale where these elements have been mobilized and leached by fluids. High Sr and Ga was found in the host rock surrounding the Garden City vein system, which contains also high Ge, Mn and Cu, indicating mobilization in high temperature and/or acidic fluids after the Murray was lithified. The fracture fill sample Stephen at Windjana is high in Zn, Co and Cu. Germanium is enriched in the Murray Fm with very consistent values of about 100 ppm over many kilometers and 200 meters elevation, similar to perviously found bedrock at Yellowknife Bay and Windjana in Gale. Zinc is highly elevated but changes significantly with elevation in Murray, often correlated with Fe/Mn, possibly indicating changing redox conditions. Pb and Se are highly enriched at Pahrump (150, 75 ppm, resp.), drop first to low values and increase again uphill towards HematiteRidge. Nodules found at Pahrump show striking evidence for (Mg, Ni)-sulfates with Nickel up to 4% in the sulfates. All together these trends might indicate hydrothermal activity. The MER APXS instruments with somewhat higher DL found similar patterns. Elevated Ge was found at Home plate, Gusev crater, and at the rim of Endeavour crater at Meridiani Planum. Together with detailed investigations of SNC meteorites, the APXS detected trace elements supplement the bulk chemistry significantly and allow new insights into the formation processes encountered on Mars

Development of phase analysis methods of impurity elements in alloys based on iron and nickel

NASA Astrophysics Data System (ADS)

Andreeva, N. A.; Anuchkin, S. N.; Volchenkova, V. A.; Kazenas, E. K.; Penkina, T. N.; Fomina, A. A.

2018-04-01

Using the method of AES with ICP, new methods have been developed for quantifying the content of various forms of existence of impurity elements: Al-Al2O3; Zr-ZrO2 in alloys based on iron (Fe-Sn) and nickel (Ni-Sn). Open systems were used to dissolve Al and Zr. To translate difficult-to-open aluminum oxides (corundum) and zirconium oxide (baddeleyite) into the solution, accelerated techniques were developed using the microwave system Mars 5. To confirm the completeness of the dissolution of oxides, a classical scheme of alloy fusion with alkali metal salts was used. Optimal analytical parameters for determining the elements: Al and Zr were chosen. The influence of matrix elements (iron and nickel) and methods of its elimination were studied. This made it possible to determine the elements in a wide concentration range from 1 • 10-3 to n% Al and from 1 • 10-4 to n% Zr without preliminary separation of the matrix with good metrological characteristics. The relative standard deviation (Sr) does not exceed 0,2. The separate determination of the contents of aluminum and aluminium oxide in the model melt of Fe-Sn-Al2O3 and zirconium and zirconium oxide in the Ni-Sn-ZrO2 model melt allowed us to estimate the number of nanoparticles participating in the heterophase interaction with tin and retired to the interface in the form of ensembles and the number of nanoparticles present in the melt and affecting the crystallization process and the structure of the metal.

Mechanism of abnormally slow crystal growth of CuZr alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, X. Q.; Lü, Y. J., E-mail: yongjunlv@bit.edu.cn; State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027

2015-10-28

Crystal growth of the glass-forming CuZr alloy is shown to be abnormally slow, which suggests a new method to identify the good glass-forming alloys. The crystal growth of elemental Cu, Pd and binary NiAl, CuZr alloys is systematically studied with the aid of molecular dynamics simulations. The temperature dependence of the growth velocity indicates the different growth mechanisms between the elemental and the alloy systems. The high-speed growth featuring the elemental metals is dominated by the non-activated collision between liquid-like atoms and interface, and the low-speed growth for NiAl and CuZr is determined by the diffusion across the interface. Wemore » find that, in contrast to Cu, Pd, and NiAl, a strong stress layering arisen from the density and the local order layering forms in front of the liquid-crystal interface of CuZr alloy, which causes a slow diffusion zone. The formation of the slow diffusion zone suppresses the interface moving, resulting in much small growth velocity of CuZr alloy. We provide a direct evidence of this explanation by applying the compressive stress normal to the interface. The compression is shown to boost the stress layering in CuZr significantly, correspondingly enhancing the slow diffusion zone, and eventually slowing down the crystal growth of CuZr alloy immediately. In contrast, the growth of Cu, Pd, and NiAl is increased by the compression because the low diffusion zones in them are never well developed.« less

Trace and rare-earth element characteristics of acidic tuffs from southern Peru and northern Bolivia and a fission-track age for the sillar of Arequipa

NASA Astrophysics Data System (ADS)

Vatin-Perignon, N.; Poupeau, G.; Oliver, R. A.; La Venu, A.; Labrin, F.; Keller, F.; Bellot-Gurlet, L.

1996-03-01

Trace-element and REE data of glass and pumices of acidic tuffs and related fall deposits erupted in southern Peru and northern Bolivia between 20 and 0.36 Ma display typical characteristics of subduction related continental arc magmatism of the CVZ with strong LILE/HFSE enrichment and non enrichment of HREE and Y. Geochemical variations of these tuffs are linked to subduction processes and controlled by changes in tectonic regimes which occured with each Quechua tectonic pulse and affected the astenospheric wedge and both the dowgoing and the overriding lithospheres. During Neogene — Pleistocene times, tuffs erupted in northern Bolivia are typically enriched in Zr, Hf, Th, Ba, LREEs and other incompatible elements and incompatible /Yb ratios are much higher relative to those erupted from southern Peru, at a given SiO 2 content (65-67 wt. for dacites, 72-73 wt.% for rhyolites). {Zr}/{Hf} ratios increase eastward from 27 to 30 and {Ce}/{Yb N} ratios from 11 to 19 reflecting the variation of degree of wedge contribution. Fractionation of the LREE over the HREE and fractionation of incompatible elements may be due to their heterogeneous distribution in the magma source. More highly fractionated REE patterns of Bolivian tuffs than Peruvian tuffs are attributed to variable amounts of contamination of magmas by lower crust. After the Quechua compressional event at 7 Ma, {Sr}/{Y} ratios of tuffs of the same age, erupted at 150-250 km or 250-400 km from the Peru-Chile trench, increase from southern Peru to northern Bolivia. These differences may be attributed to the subduction of a swarm oceanic lithosphere under the Bolivian Alti-plano, leading to partial melting of the sudbucted lithosphere. New FT dating of obsidian fragments of the sillar of Arequipa at 2.42 ± 0.11 Ma. This tuff dates the last Quechua compressional upper Pliocene phase ( 2.5 Ma) and confirms that the sillar is not contemporaneous with the Toba 76 tuff or the Perez ignimbrite of northern Bolivia. Geochemical characteristics of tuffs erupted before and after this last compressional phase remained the same and provide evidence that the upper Miocene ( 7 Ma) compressional deformations played the most important role on the variability of the geochemical characteristics of the southern Peruvian and northern Bolivian tuffs.

Thermophysical properties of 22 pure metals in the solid and liquid state - The pulse-heating data collection

NASA Astrophysics Data System (ADS)

Hüpf, T.; Cagran, C.; Pottlacher, G.

2011-05-01

The workgroup of subsecond thermophysics in Graz has a long tradition in performing fast pulseheating experiments on metals and alloys. Thereby, wire-shaped specimens are rapidly heated (108 K/s) by a large current-pulse (104 A). This method provides thermophysical properties like volume-expansion, enthalpy and electrical resistivity up to the end of the liquid phase. Today, no more experiments on pure metals are to be expected, because almost all elements, which are suitable for pulse-heating so far, have been investigated. The requirements for pulse-heating are: a melting point which is high enough to enable pyrometric temperature measurements and the availability of wire-shaped specimens. These elements are: Co, Cu, Au, Hf, In, Ir, Fe, Pb, Mo, Ni, Nb, Pd, Pt, Re, Rh, Ag, Ta, Ti, W, V, Zn, and Zr. Hence, it is the correct time to present the results in a collected form. We provide data for the above mentioned quantities together with basic information on each material. The uniqueness of this compilation is the high temperature range covered and the homogeneity of the measurement conditions (the same method, the same laboratory, etc.). The latter makes it a good starting point for comparative analyses (e.g. a comparison of all 22 enthalpy traces is in first approximation conform with the rule of Dulong-Petit which states heat capacity - the slope of enthalpy traces - as a function of the number of atoms). The data is useful for input parameters in numerical simulations and it is a major purpose of our ongoing research to provide data for simulations of casting processes for the metal working industry. This work demonstrates some examples of how a data compilation like this can be utilized. Additionally, the latest completive measurement results on Ag, Ni, Ti, and Zr are described.

The importance of mantle wedge heterogeneity to subduction zone magmatism and the origin of EM1

NASA Astrophysics Data System (ADS)

Turner, Stephen J.; Langmuir, Charles H.; Dungan, Michael A.; Escrig, Stephane

2017-08-01

The composition of the convecting asthenospheric mantle that feeds the mantle wedge can be investigated via rear-arc lavas that have minimal slab influence. This "ambient mantle wedge" composition (the composition of the wedge prior to the addition of a slab component) varies substantially both worldwide and within individual arcs. 143Nd/144Nd measurements of rear-arc samples that have minimal slab influence are similar to 143Nd/144Nd in the stratovolcanoes of the adjacent volcanic fronts, suggesting that 143Nd/144Nd of arc-front volcanics are largely inherited from the ambient mantle composition. 143Nd/144Nd correlates with ratios such as Th/U, Zr/Nb, and La/Sm, indicating that these ratios also are strongly influenced by ambient wedge heterogeneity. The same phenomenon is observed among individual volcanoes from the Chilean Southern Volcanic Zone (SVZ), where along-strike variability of the volcanic front tracks that of rear-arc monogenetic volcanics. Depleted mantle wedges are more strongly influenced by slab-derived components than are enriched wedges. This leads to surprising trace element correlations in the global dataset, such as between Pb/Nb and Zr/Nb, which are not explicable by variable compositions or fluxes of slab components. Depleted ambient mantle is present beneath arcs with back-arc spreading; relatively enriched mantle is present adjacent to continents. Ambient mantle wedge heterogeneity both globally and regionally forms isotope mixing trajectories for Sr, Nd and Hf between depleted mantle and EM1-type enriched compositions as represented by Gough Island basalts. Making use of this relationship permits a quantitative match with the SVZ data. It has been suggested that EM1-type mantle reservoirs are the result of recycled lower continental crust, though such models do not account for certain trace element ratios such as Ce/Pb and Nb/U or the surprisingly homogeneous trace element compositions of EM1 volcanics. A model in which the EM1 end-member found in continental arcs is produced by low-degree melt-metasomatism of the sub-continental lithospheric mantle may be more plausible. The 143Nd/144Nd maximum along the SVZ may be a consequence of either rifting and collision of two ancient lithospheric domains or a slab tear. The correspondence of mantle wedge variations with EM1 suggests a potential role for metasomatized sub-continental lithosphere in creating EM1 sources globally.

Trace element behavior in hydrothermal experiments: Implications for fluid processes at shallow depths in subduction zones

NASA Astrophysics Data System (ADS)

You, C.-F.; Castillo, P. R.; Gieskes, J. M.; Chan, L. H.; Spivack, A. J.

1996-05-01

Chemical evaluation of fluids affected during progressive water-sediment interactions provides critical information regarding the role of slab dehydration and/or crustal recycling in subduction zones. To place some constraints on geochemical processes during sediment subduction, reactions between décollement sediments and synthetic NaCl-CaCl 2 solutions at 25-350°C and 800 bar were monitored in laboratory hydrothermal experiments using an autoclave apparatus. This is the first attempt in a single set of experiments to investigate the relative mobilities of many subduction zone volatiles and trace elements but, because of difficulties in conducting hydrothermal experiments on sediments at high P-T conditions, the experiments could only be designed for a shallow (˜ 10 km) depth. The experimental results demonstrate mobilization of volatiles (B and NH 4) and incompatible elements (As, Be, Cs, Li, Pb, Rb) in hydrothermal fluids at relatively low temperatures (˜ 300°C). In addition, a limited fractionation of light from heavy rare earth elements (REEs) occurs under hydrothermal conditions. On the other hand, the high field strength elements (HFSEs) Cr, Hf, Nb, Ta, Ti, and Zr are not mobile in the reacted fluids. The observed behavior of volatiles and trace elements in hydrothermal fluids is similar to the observed enrichment in As, B, Cs, Li, Pb, Rb, and light REEs and depletion in HFSEs in arc magmas relative to magmas derived directly from the upper mantle. Thus, our work suggests a link between relative mobilities of trace elements in hydrothermal fluids and deep arc magma generation in subduction zones. The experimental results are highly consistent with the proposal that the addition of subduction zone hydrous fluids to the subarc mantle, which has been depleted by previous melting events, can produce the unique characteristics of arc magmas. Moreover, the results suggest that deeply subducted sediments may no longer have the composition necessary to generate the other distinct characteristics, such as the B-δ 11 B and B- 10Be systematics, of arc lavas. Finally, the mobilization of B, Cs, Pb, and light REEs relative to heavy REEs in the hydrothermal fluids fractionate the ratios of B/Be, B/Nb, Cs/Rb, Pb/Ce, La/Ba and LREE/HREE, which behave conservatively during normal magmatic processes. These results demonstrate that the composition of slab-derived fluids has great implications for the recycling of elements; not only in arc magmas but also in mantle plumes.

Nanocrystalline Fe/Zr alloys: preparation by using mechanical alloying and mechanical milling processes

NASA Astrophysics Data System (ADS)

Rodríguez, V. A. Peña; Medina, J. Medina; Marcatoma, J. Quispe; Ayala, Ch. Rojas; Landauro, C. V.; Baggio-Saitovitch, E. M.; Passamani, E. C.

2011-11-01

Nanocrystalline Fe/Zr alloys have been prepared after milling for 9 h the mixture of elemental Fe and Zr powders or the arc-melting produced Fe2Zr alloy by using mechanical alloying and mechanical milling techniques, respectively. X-ray and Mössbauer results of the Fe and Zr powders, mechanically alloyed, suggest that amorphous Fe2Zr phase and \\upalpha-Fe(Zr) nanograins have been produced with relative concentrations of 91% and 9%, respectively. Conversely, the results of the mechanically milled Fe2Zr alloy indicate that nanograins of the Fe2Zr alloy have been formed, surrounded by a magnetic inter-granular phase that are simultaneously dispersed in a paramagnetic amorphous phase.

Historical trace element accumulation in marine sediments from the Tamaulipas shelf, Gulf of Mexico: An assessment of natural vs anthropogenic inputs.

PubMed

Celis-Hernandez, Omar; Rosales-Hoz, Leticia; Cundy, Andrew B; Carranza-Edwards, Arturo; Croudace, Ian W; Hernandez-Hernandez, Hector

2018-05-01

The Gulf of Mexico is considered one of the world's major marine ecosystems, supporting important fisheries and habitats such as barrier islands, mangrove forests, seagrass beds, coral reefs etc. It also hosts a range of complex offshore petroleum exploration, extraction, and refining industries, which may have chronic or acute impacts on ecosystem functioning. Previous work on the marine effects of this activity is geographically incomplete, and has tended to focus on direct hydrocarbon impacts, while impacts from other related contaminants (e.g. heavy metals, salt-rich drilling muds) which may be discharged from oil facilities have not been widely assessed. Here, we examine historical trace element accumulation in marine sediments collected from four sites in the Tamaulipas shelf, Gulf of Mexico, in the area of the Arenque oil field. Dated sediment cores were used to examine the sources, and historical and contemporary inputs, of trace metals (including those typically present in oil industry discharges) and their potential biological impact in the Tamaulipas aquatic environment over the last 100years. CaO (i.e. biogenic component) normalized data showed increasing V, Cr, Zn, Cu, Pb, Zr and Ba towards the sediment surface in three of the four cores, with Ba and V (based on an adverse effect index) possibly associated with adverse effects on organisms. Dated Ba/CaO profiles show an increase of 30-137% after opening of oil installations in the study area, and can be broadly correlated with increasing oil industry activities across the wider Gulf of Mexico. Data do not record however a clear enhancement of Ba concentration in sediment cores collected near to oil platforms over more distal cores, indicating that any Ba released from drilling platforms is incorporated quickly into the sediments around the drilling sites, and once this element has been deposited its rate of resuspension and mobility is low. Sediment core data from the Tamaulipas shelf show the influence of oil industry activities on selected trace element concentrations, with Ba/CaO broadly correlating with increasing oil industry activities across the wider Gulf of Mexico. Copyright © 2017 Elsevier B.V. All rights reserved.

The trace and Pb isotope chemistry of the Jan Mayen Fracture Zone and the extinct Aegir Ridge

NASA Astrophysics Data System (ADS)

Sayit, K.; Hanan, B. B.; Ito, G.; Howell, S. M.; Vogt, P. R.; Breivik, A. J.; Mjelde, R.; Pedersen, R.

2012-12-01

The extinct Aegir Ridge (AR) was active during the early opening of the N-Atlantic, 54 to 25 Ma, when spreading jumped to the Kolbeinsey Ridge. Crustal thickness produced by the AR is low (3.5 to 6 km), and the magmatically starved Norway Basin appears as a hole in the surrounding excess volcanism of the Iceland hotspot. Two possible alternatives are; either the lithospheric structure of the Jan Mayen micro-continent (JMMC) blocked the plume flow to the AR, and/or Iceland plume material reaching the ridge experienced a previous melt extraction, leading to relatively low melt production. We report the trace element and Pb isotope systematics of the mafic rocks dredged from the AR ~64-69° N and adjacent Jan Mayen FZ. On the basis of the immobile trace element chemistry, several groups are identified, with a large range of Zr/Nb (2.7-60.7). A very-depleted group ([Ce/Yb]N = 0.3) was found in the Jan Mayen FZ, while the most enriched, OIB-like group ([Ce/Yb]N = 12.4) was recovered from the ridge flank scarps. A notable feature of the Aegir samples is variable Th enrichment relative Nb (Th/Nb = 0.07-0.49), similar to subduction zone signatures. In terms of Pb isotopes, the samples show significant variations that correlate with trace element chemistry (206Pb/204Pb: 207Pb/204Pb: 208Pb/204Pb = 16.63-18.81:15.16-15.55:36.67-38.62). The Pb systematics of the Aegir rocks are compatible with a three-component mixing model with mixing trends between the C-like Iceland plume component and a mixture that is composed of EM-1-type material and depleted MORB asthenosphere. The presence of the C-like isotope compositions in the Aegir samples from the Jan Mayen FZ and ridge flank scarps suggests that Iceland plume material has been tapped. However, the very-depleted trace element signatures indicate that the plume component was previously melt depleted. Apparently, the JMMC impeaded flow of enriched plume material to the AR. The Aegir rocks Pb isotope signature may represent pollution of the NA MORB source, during early opening of the ocean basin, by material dispersed during interaction of the Iceland plume and the continental lithosphere.

Origin and evolution of the Ilmeny-Vishnevogorsky carbonatites (Urals, Russia): insights from trace-element compositions, and Rb-Sr, Sm-Nd, U-Pb, Lu-Hf isotope data

NASA Astrophysics Data System (ADS)

Nedosekova, I. L.; Belousova, E. A.; Sharygin, V. V.; Belyatsky, B. V.; Bayanova, T. B.

2013-02-01

The carbonatites of the Ilmeny-Vishnevogorsky Alkaline Complex (IVAC) are specific in geological and geochemical aspects and differ by some characteristics from classic carbonatites of the zoned alkaline-ultramafic complexes. Geological, geochemical and isotopic data and comparison with relevant experimental systems show that the IVAC carbonatites are genetically related to miaskites, and seem to be formed as a result of separation of carbonatite liquid from a miaskitic magma. Appreciable role of a carbonate fluid is established at the later stages of carbonatite formation. The trace element contents in the IVAC carbonatites are similar to carbonatites of the ultramafic-alkaline complexes. The characteristic signatures of the IVAC carbonatites are a high Sr content, a slight depletion in Ba, Nb, Та, Ti, Zr, and Hf, and enrichment in HREE in comparison with carbonatites of ultramafic-alkaline complexes. This testifies a specific nature of the IVAC carbonatites related to the fractionation of a miaskitic magma and to further Late Paleozoic metamorphism. Isotope data suggest a mantle source for IVAC carbonatites and indicate that moderately depleted mantle and enriched EMI-type components participated in magma generation. The lower crust could have been involved in the generation of the IVAC magma.

The Interior of the Moon, Core Formation, and the Lunar Hotspot: What Samples Tell Us

NASA Astrophysics Data System (ADS)

Neal, C. R.

1999-01-01

Remotely-gathered Lunar Prospector data have demonstrated the existence of a lunar "hotspot" on the near side of the Moon. This hotspot contains relatively high abundances of KREEPy incompatible trace elements (i.e., Th). It is generally accepted that primordial KREEP or urKREEP represents the residual liquid after the crystallization of a lunar magma ocean (LMO). The crystalline products from the LMO formed the source regions for the mare basalts. Lunar volcanic glasses cannot be genetically related to the crystalline mare basalts, and experimental petrology indicates they are derived from greater (> 400 km) depths than the mare basalts. Questions to be addressed include: (1) What was the extent of LMO melting? (2) What is the composition of the core? (3) Are there distinct geochemical reservoirs in the Moon? (4) Is there evidence of garnet in the lunar interior? (5) What caused the formation of the lunar hotspot? The scale of the LMO has been suggested to be whole Moon melting or only the outer about 400 km. If whole Moon melting is invoked, then differentiation of the Moon into a flotation plagioclase-rich crust, a mafic mineral cumulate mantle, and a Fe-rich core is more easily facilitated. However, as pointed out, if the material that formed the Moon came primarily from the already-differentiated Earth mantle, there may not be enough Fe to form a metallic Fe core on the Moon. Authors have suggested that the lunar core is made up of dense, ilmenite-rich, late-stage cumulates from the LMO. This can be tested by examining the Zr/Hf ratios of mare basalts and, where possible, the volcanic glasses. Partition coefficients for Zr and Hf in ilmenite are 0.29-0.32 and 0.4-0.43, respectively, with Zr being less compatible. Therefore, extraction of an "ilmenite" core would have a profound effect on the Zr/Hf ratio of urKREEP as ilmenite is a late-stage fractionating LMO phase. Assuming either a "primitive mantle" or chondritic starting material with a Zr/Hf ratio of 36-37, ilmenite extraction will increase this ratio in the residual liquid. Conversely, derivation of a melt from a source rich in ilmenite will produce a melt of lower Zr/ Hf ratio. Hughes and Schmitt defined a mean Zr/Hf for KREEP of 41.0 +/- 0.4, about 39 for Apollo 15 basalts, and 30-32 for Apollo 11, 12, and 17 basalts, with the decreases in Zr/Hf broadly correlating with La/Yb. However, literature data for Apollo 15 KREEP basalts and the KREEP-rich Apollo 14 mare basalts exhibit little variation in Zr/Hf from 36, indicating the KREEP component did not result from a major fractionation of ilmenite and suggesting that the lunar core is probably metallic in overall composition. With volcanic glasses being unrelated to the mare basalts and derived from greater depths, compositional comparisons allow their source regions to be compared. Highly siderophile elements Au and Ir are more abundant in the glasses relative to the basalts. As these elements are generally incompatible in silicate minerals, crystal fractionation experienced by the basalts will tend to increase the Au and It abundances. Therefore, the glasses may be derived from a source enriched in highly siderophile elements such as the platinum-group elements (PGEs) represented by Ir, relative to the source of the basalts. This observation can be accommodated with the basalts being derived from the LMO cumulates and the glasses derived from a source that represents "primitive Moon" that did not melt and, therefore, did not have its budget of PGEs and Au reduced through core formation. This can be tested by analyzing mare basalts and glasses for the PGEs. Although analytically challenging, the first PGE patterns in lunar samples were demonstrated that the source regions for the different Apollo 12 basalts could not be differentiated on the basis of PGE budgets, although the profiles are typical of silicate melts. Analysis of other trace-element data indicate that the high-field-strength elements can be used to differentiate between high- and low-Ti basalts. Also, the volcanic glasses were derived from a source with a higher Zr/Y ratio relative to the basalts, consistent with retention of garnet in the residue. If the glasses were derived from > 400 km, garnet could be stable. It is concluded that the volcanic glasses were derived from a source that contained garnet, but escaped the melting that formed the LMO. The mare basalts were derived from the LMO cumulate pile. Basaltic samples from Apollo 14 exhibit a range in ITE. They also exhibit a range of ages from 4.33 Ga to 3.96 Ga with the older basalts being KREEP-poor and the younger being KREEP-rich. Prospector mapping has identified relatively high Th abundances in this area, suggesting a large KREEP component is present at or near the surface. LMO "layer cake models" have residual urKREEP sandwiched between the mafic cumulate mantle and the plagioclase flotation cumulate crust. However, late-stage cumulates and the residual liquid will be more dense that the early mafic cumulates resulting in gravitational instabilities and overturn of the cumulate pile. This could transport urKREEP to the base of the LMO cumulate pile, but above the glass source region. The effect of Earth on the symmetry of the Moon has displaced the low-density crust, producing a thicker crust on the farside. This has produced an offset of the center of mass for the Moon toward Earth. It is suggested that the gravitational forces of the Earth pooled the urKREEP beneath at the base of the LMO on the lunar nearside. Heating through radioactive decay produced thermal instabilities, resulting in a plume of hot, KREEPy material rising adiabatically beneath the Apollo 14 site. The oldest Apollo basalts contain no evidence of a KREEPy component, suggesting diapiric rise of the KREEPy plume had not occurred at this time. Additional information contained in original.

Magnetic properties enhancement of melt spun CoZrB ribbons by elemental substitutions

NASA Astrophysics Data System (ADS)

Chang, H. W.; Tsai, C. F.; Hsieh, C. C.; Shih, C. W.; Chang, W. C.; Shaw, C. C.

2013-11-01

Effect of elemental substitution of M (M=C, Cu, Ga, Al and Si) for Zr on the magnetic properties, phase evolution, and microstructure of melt spun Co80Zr18-xMxB2 (x=0-2) ribbons have been investigated. The x-ray diffraction (XRD) and thermal magnetic analysis (TMA) results showed that two magnetically soft phases, namely fcc-Co and Co23Zr6, coexisted with hard phase Co5Zr in Co80Zr17M1B2 ribbons with M=Cu, Ga, Al and Si, while an extra unknown magnetic phase was present in ribbons with M=C. The ribbons with M=C and Si were found to improve the remanence (σr) of the Co80Zr17M1B2 ribbons. However, only M=Si could improve the whole magnetic properties, including Br, intrinsic coercivity (iHc) and energy product ((BH)max) of the above ribbons. The optimal magnetic properties of Br=5.2 kG, iHc=4.5 kOe, and (BH)max=5.3 MGOe were obtained in Co80Zr17Si1B2 ribbons, which possessed Co5Zr and minor fcc-Co phases with much finer grain size (10-30 nm) in comparison with its counterpart Co80Zr18B2 (20-60 nm).

Large enhancement of superconductivity in Zr point contacts.

PubMed

Aslam, Mohammad; Singh, Chandan; Das, Shekhar; Kumar, Ritesh; Datta, Soumya; Halder, Soumyadip; Gayen, Sirshendu; Kabir, Mukul; Sheet, Goutam

2018-04-30

For certain complex superconducting systems, the superconducting properties get enhanced under mesoscopic point contacts made of elemental non-superconducting metals. However, understanding of the mechanism through which such contact induced local enhancement of superconductivity happens has been limited due to the complex nature of such compounds. In this paper we present a large enhancement of superconducting transition temperature (T_c) and superconducting energy gap (Δ) in a simple elemental superconductor Zr. While bulk Zr shows a critical temperature around 0.6K, superconductivity survives at Ag/Zr and Pt/Zr point contacts up to 3K with a corresponding five-fold enhancement of Δ. Further, the first-principles calculations on a model system provide useful insights. We show that the enhancement in superconducting properties can be attributed to a modification in the electron-phonon coupling accompanied by an enhancement of the density of states which involves the appearance of a new electron band at the Ag/Zr interfaces. © 2018 IOP Publishing Ltd.

Genesis of Cenozoic intraplate high Mg# andesites in Northeast China

NASA Astrophysics Data System (ADS)

Liu, J. Q.; Chen, L. H.; Zhong, Y.; Wang, X. J.

2017-12-01

High-Mg# andesites (HMAs) are usually generated in the converged plate boundary and have genetic relationships with slab subduction. However, it still remained controversial about the origin of those HMAs erupted in the intra-plate setting. Here we present major, trace element, and Sr-Nd-Pb-Hf isotopic compositions for the Cenozoic intra-plate HMAs from Northeast China to constrain their origin and formation process. Cenozoic Xunke volcanic rocks are located in the northern Lesser Khingan Range, covering an area of about 3, 000 km2. These volcanic rocks are mainly basaltic andesite and basaltic trachyandesite, with only several classified as trachyandesite and andesites. They have high SiO2 contents (54.3-57.4 wt%) and Mg# (49.6-57.8), falling into the scope of high Mg# andesites. The Xunke HMAs are enriched in large ion lithophile elements but depleted in high field strength elements, with positive Ba, K, Sr and negative Zr-Hf, and Ti anomalies. Their trace element absolute concentrations are between those of potassic basalts and Wuchagou HMAs. The Xunke HMAs have relatively enriched Sr-Nd-Hf isotopes (87Sr/86Sr = 0.705398-0.705764, ɛNd=-8.8-3.8, ɛHf=0.5-11.7), and low radiogenic Pb isotopes (206Pb/204Pb = 16.701-17.198), towards to the EM1 end-member, which indicates that they are ultimately derived from ancient, recycled crustal components. Primitive silica-rich melts were generated from higher degrees of partial melting of recycled crustal materials (relative to potassic basalts) and then interacted with the peridotite to produce the Xunke HMAs.

[A surface reacted layer study of titanium-zirconium alloy after dental casting].

PubMed

Zhang, Y; Guo, T; Li, Z; Li, C

2000-10-01

To investigate the influence of the mold temperature on the surface reacted layer of Ti-Zr alloy castings. Ti-Zr alloy was casted into a mold which was made of a zircon (ZrO2.SiO2) for inner coating and a phosphate-bonded material for outer investing with a casting machine (China) designed as vacuum, pressure and centrifuge. At three mold temperatures (room temperature, 300 degrees C, 600 degrees C) the Ti-Zr alloy was casted separately. The surface roughness of the castings was calculated by instrument of smooth finish (China). From the surface to the inner part the Knoop hardness and thickness in reacted layer of Ti-Zr alloy casting was measured. The structure of the surface reacted layer was analysed by SEM. Elemental analyses of the interfacial zone of the casting was made by element line scanning observation. The surface roughness of the castings was increased significantly with the mold temperature increasing. At a higher mold temperature the Knoop hardness of the reactive layer was increased. At the three mold temperature the outmost surface was very hard, and microhardness data decreased rapidly where they reached constant values. The thickness was about 85 microns for castings at room temperature and 300 degrees C, 105 microns for castings at 600 degrees C. From the SEM micrograph of the Ti-Zr alloy casting, the surface reacted layer could be divided into three different layers. The first layer was called non-structure layer, which thickness was about 10 microns for room temperature group, 20 microns for 300 degrees C and 25 microns for 600 degrees C. The second layer was characterized by coarse-grained acicular crystal, which thickness was about 50 microns for three mold temperatures. The third layer was Ti-Zr alloy. The element line scanning showed non-structure layer with higher level of element of O, Al, Si and Zr, The higher the mold temperature during casting, the deeper the Si permeating and in the second layer the element Si could also be found. The mold temperature is one of the major factors influencing to casting quality. In order to reduce the surface reacted layer of Ti-Zr alloy castings, the lower mold temperature and the investment without Si should be chosen.

Selective sorption of lead, cadmium and zinc ions by a polymeric cation exchanger containing nano-Zr(HPO3S)2.

PubMed

Zhang, Qingrui; Pan, Bingcai; Pan, Bingjun; Zhang, Weiming; Jia, Kun; Zhang, Quanxing

2008-06-01

A novel polymeric hybrid sorbent, namely ZrPS-001, was fabricated for enhanced sorption of heavy metal ions by impregnating Zr(HPO3S)2 (i.e., ZrPS) nanoparticles within a porous polymeric cation exchanger D-001. The immobilized negatively charged groups bound to the polymeric matrix D-001 would result in preconcentration and permeation enhancement of target metal ions prior to sequestration, and ZrPS nanoparticles are expected to sequester heavy metals selectively through an ion-exchange process. Highly effective sequestration of lead, cadmium, and zinc ions from aqueous solution can be achieved by ZrPS-001 even in the presence of competing calcium ion at concentration several orders of magnitude greater than the target species. The exhausted ZrPS-001 beads are amenable to regeneration with 6 M HCI solution for repeated use without any significant capacity loss. Fixed-bed column treatment of simulated waters containing heavy metals at high or trace levels was also performed. The content of heavy metals in treated effluent approached or met the WHO drinking water standard.

The behaviour of REE and Zr-Hf fractionation in the volcanic waters of Nevado del Ruiz system (Colombia)

NASA Astrophysics Data System (ADS)

Inguaggiato, Claudio; Censi, Paolo; Zuddas, Pierpaolo; Makario Londoño, John; Chacón, Zoraida; Alzate, Diego; Brusca, Lorenzo; D'Alessandro, Walter

2015-04-01

The geochemical behaviour of Rare Earth Element (REE), Zr and Hf have been investigated in the thermal waters of Nevado del Ruiz volcanic system. These fluids are characterised by a wide range of pH ranging between 1.0 and 8.8. The acidic waters are sulphate dominated with different Cl/SO4 ratios. The Nevado del Ruiz waters allowed to investigate the behaviour of investigated elements in a wide spectrum of pH and chemical composition of water. The important role of the pH and the ionic complexes have been evidenced in the distribution of REE, Zr and Hf in the aqueous phase. The pH rules the precipitation of authigenic oxyhydroxides of Fe, Al producing changes in REE, Zr, Hf amount and strong anomalies of Cerium and Europium. Y-Ho and Zr-Hf (twin pairs) have different behaviour in strong acidic waters with respect to the water with higher pH. Yttrium and Ho have the same behaviour of Zr and Hf in waters with pH near neutral-to-neutral, showing super-chondritic ratios. The twin pairs showed to be sensitive to the co-precipitation and/or adsorption onto the surface of authigenic particulate suggesting an enhanced scavenging of Ho and Hf respect to Y and Zr, leading to super-chondritic ratios. In acidic waters a different behaviour of twin pairs occurs with chondritic Y/Ho ratios (reflecting the Y/Ho ratio of average local rock) and sub-chondritic Zr/Hf ratios. For the first time, Zr and Hf have been investigated in natural acidic fluids to understand the behaviour of these elements in extreme acidic conditions and different major anions chemistry. Zr/Hf molar ratio changes from 4.75 to 49.29 in water with pH<3.6. In strong acidic waters, a different fractionation of Zr and Hf have been recognised as function of major anion contents (Cl and SO4), suggesting the formation of complexes leading to sub-chondritic Zr/Hf molar ratios.

The Finero phlogopite-peridotite massif: an example of subduction-related metasomatism

NASA Astrophysics Data System (ADS)

Zanetti, Alberto; Mazzucchelli, Maurizio; Rivalenti, Giorgio; Vannucci, Riccardo

The Finero peridotite massif is a harzburgite that suffered a dramatic metasomatic enrichment resulting in the pervasive presence of amphibole and phlogopite and in the sporadic occurrence of apatite and carbonate (dolomite)-bearing domains. Pyroxenite (websterite) dykes also contain phlogopite and amphibole, but are rare. Peridotite bulk-rock composition retained highly depleted major element characteristics, but was enriched in K, Rb, Ba, Sr, LREE (light rare earth elements) (LaN/YbN=8-17) and depleted in Nb. It has high radiogenic Sr (87Sr/86Sr(270)=0.7055-0.7093), low radiogenic Nd (ɛNd(270)=-1 to -3) and EMII-like Pb isotopes. Two pyroxenite - peridotite sections examined in detail show the virtual absence of major and trace element gradients in the mineral phases. In both rock types, pyroxenes and olivines have the most unfertile major element composition observed in Ivrea peridotites, spinels are the richest in Cr, and amphibole is pargasite. Clinopyroxenes exhibit LREE-enriched patterns (LaN/YbN 16), negative Ti and Zr and generally positive Sr anomaly. Amphibole has similar characteristics, except a weak negative Sr anomaly, but incompatible element concentration 1.9 (Sr) to 7.9 (Ti) times higher than that of coexisting clinopyroxene. Marked geochemical gradients occur toward apatite and carbonate-bearing domains which are randomly distributed in both the sections examined. In these regions, pyroxenes and amphibole (edenite) arelower in mg## and higher in Na2O, and spinels and phlogopite are richer in Cr2O3. Both the mineral assemblage and the incompatible trace element characteristics of the mineral phases recall the typical signatures of ``carbonatite'' metasomatism (HFSE depletion, Sr, LILE and LREE enrichment). Clinopyroxene has higher REE and Sr concentrations than amphibole (amph/cpxDREE,Sr=0.7-0.9) and lower Ti and Zr concentrations. It is proposed that the petrographic and geochemical features observed at Finero are consistent with a subduction environment. The lack of chemical gradients between pyroxenite and peridotite is explained by a model where melts derived from an eclogite-facies slab infiltrate the overhanging harzburgitic mantle wedge and, because of the special thermal structure of subduction zones, become heated to the temperature of the peridotite. If the resulting temperature is above that of the incipient melting of the hydrous peridotite system, the slab-derived melt equilibrates with the harzburgite and a crystal mush consisting of harzburgite and a silica saturated, hydrous melt is formed. During cooling, the crystal mush crystallizes producing the observed sequence of mineral phases and their observed chemical characteristics. In this context pyroxenites are regions of higher concentration of the melt in equilibrium with the harzburgite and not passage-ways through which exotic melts percolated. Only negligible chemical gradients can appear as an effect of the crystallization process, which also accounts for the high amphibole/clinopyroxene incompatible trace element ratios. The major element refractory composition is explained by an initially high peridotite/melt ratio. The apatite, carbonate-bearing domains are the result of the presence of some CO2 in the slab-derived melt. The CO2/H2O ratio in the peridotite mush increased by crystallization of hydrous phases (amphibole and phlogopite) locally resulting in the unmixing of a late carbonate fluid. The proposed scenario is consistent with subduction of probably Variscan age and with the occurrence of modal metasomatism before peridotite incorporation in the crust.

Diurnal variations of dissolved and colloidal organic carbon and trace metals in a boreal lake during summer bloom.

PubMed

Pokrovsky, O S; Shirokova, L S

2013-02-01

This work describes variation of element concentration in surface water of a subarctic organic-rich lake during the diurnal cycle of photosynthesis. An unusually hot summer 2010 in European part of subarctic Russia produced elevated surface water temperature (28-30 °C) and caused massive cyanobacterial bloom. Diurnal variation of ~40 dissolved macro and trace elements and organic carbon were recorded in the humic Lake Svyatoe in the White Sea drainage basin. Two days continuous measurements with 3 h sampling steps at the surface (0.5 m) allowed tracing cyanobacterial activity via pH and O₂ measurement and revealed constant concentrations (within ±20-30%) of all major elements (Na, Mg, Cl, SO₄, K, Ca), organic and inorganic carbon and most trace elements (Li, B, Sc, Ti, Ni, Cu, Ga, As, Rb, Sr, Y, Zr, Mo, Sb, medium and heavy REEs, Hf, Pb, Th, U). The concentration of Mn demonstrated a factor of 3 decrease during the day following Mn adsorption onto cyanobacterial cells due to ~1 pH unit raise during the photosynthesis and Mn release during the night due to desorption from the cell surface. The role of Mn(II) photo-oxidation by reactive oxygen species could be also pronounced, although its contribution to Mn diurnal variation was much smaller than the adsorption at the cell surfaces. Similar pattern, but with much lesser variations (c.a., 10-20%), was recorded for Ba and Fe. On-site ultrafiltration technique allowed to distinguish between low molecular weight (LMW) complexes (<1 kDa) and high molecular weight (HMW) colloids (1 kDa-0.22 μm) and to assess their diurnal pattern. Colloidal Al and Fe were the highest during the night, when the contribution of HMW allochthonous colloids was maximal. Typical insoluble trivalent and tetravalent elements exhibited constant complexation (>80-90%) with HMW allochthonous organics, independent on the diel photosynthetic cycle. Finally, biologically-relevant metals (Cu, Co, Cr, V, and Ni) demonstrated significant variations of colloidal fractions (from 10 to 60%) not directly related to the photosynthesis. The majority of possible metal nutrients, being strongly associated with organic and organo-mineral colloids do not exhibit any measurable concentration variation during photosynthesis. The two types of element behavior during cyanobacterial bloom in the water column--constant concentration and sinusoidal variations--likely depend on element speciation in solution and their relative affinity to surfaces of aquatic microorganisms and complexation with authochthonous and allochthonous organic matter. Copyright © 2012 Elsevier Ltd. All rights reserved.

Influence of finish line in the distribution of stress trough an all ceramic implant-supported crown.

PubMed Central

SANNINO, G.; GLORIA, F.; OTTRIA, L.; BARLATTANI, A.

2010-01-01

SUMMARY Porpose. The aim of this study was to evaluate, by finite element analysis (FEA), the influence of finish line on stress distribution and resistance to the loads of a ZrO2 crown and porcelain in implant-supported. Material and methods. The object of this analysis consisted of a fxture, an abutment, a passing screw, a layer of cement, a framework crown, a feldspatic porcelain veneering. The abutment’s marginal design was used in 3 different types of preparation: feather edge, slight chamfer and 50°, each of them was of 1 mm depth over the entire circumference. The ZrO2Y-TZP coping was 0.6 mm thick. Two material matching for the abutment and the framework was used for the simulations: ZrO2 framework and ZrO2 abutment, ZrO2 framework and T abutment. A 600 N axial force distributed over the entire surface of the crown was applied. The numerical simulations with finite elements were used to verify the different distribution of equivalent von Mises stress for three different geometries of abutment and framework. Results Slight chamfer on the matching ZrO2 - ZrO2 is the geometry with minimum equivalent stress of von Mises. Even for T abutment and ZrO2 framework slight chamfer is the best configuration to minimize the localized stress. Geometry that has the highest average stress is one with abutment at 50°, we see a downward trend for all three configurations using only zirconium for both components. Conclusions Finite element analysis. performed for the manifacturing of implant-supported crown, gives exact geometric guide lines about the choice of chamfer preparation, while the analysis of other marginal geometries suggests a possible improved behavior of the mating between ZrO2 abutment and ZrO2 coping. for three different geometries of the abutment and the coping. PMID:23285359

Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

NASA Astrophysics Data System (ADS)

Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

2017-05-01

The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.

Determination of minor and trace elements in kidney stones by x-ray fluorescence analysis

NASA Astrophysics Data System (ADS)

Srivastava, Anjali; Heisinger, Brianne J.; Sinha, Vaibhav; Lee, Hyong-Koo; Liu, Xin; Qu, Mingliang; Duan, Xinhui; Leng, Shuai; McCollough, Cynthia H.

2014-03-01

The determination of accurate material composition of a kidney stone is crucial for understanding the formation of the kidney stone as well as for preventive therapeutic strategies. Radiations probing instrumental activation analysis techniques are excellent tools for identification of involved materials present in the kidney stone. In particular, x-ray fluorescence (XRF) can be very useful for the determination of minor and trace materials in the kidney stone. The X-ray fluorescence measurements were performed at the Radiation Measurements and Spectroscopy Laboratory (RMSL) of department of nuclear engineering of Missouri University of Science and Technology and different kidney stones were acquired from the Mayo Clinic, Rochester, Minnesota. Presently, experimental studies in conjunction with analytical techniques were used to determine the exact composition of the kidney stone. A new type of experimental set-up was developed and utilized for XRF analysis of the kidney stone. The correlation of applied radiation source intensity, emission of X-ray spectrum from involving elements and absorption coefficient characteristics were analyzed. To verify the experimental results with analytical calculation, several sets of kidney stones were analyzed using XRF technique. The elements which were identified from this techniques are Silver (Ag), Arsenic (As), Bromine (Br), Chromium (Cr), Copper (Cu), Gallium (Ga), Germanium (Ge), Molybdenum (Mo), Niobium (Nb), Rubidium (Rb), Selenium (Se), Strontium (Sr), Yttrium (Y), Zirconium (Zr). This paper presents a new approach for exact detection of accurate material composition of kidney stone materials using XRF instrumental activation analysis technique.

Petrography and geochemistry of clastic sedimentary rocks as evidences for provenance of the Lower Cambrian Lalun Formation, Posht-e-badam block, Central Iran

NASA Astrophysics Data System (ADS)

Etemad-Saeed, N.; Hosseini-Barzi, M.; Armstrong-Altrin, John S.

2011-09-01

Petrography and geochemistry (major, trace and rare earth elements) of clastic rocks from the Lower Cambrian Lalun Formation, in the Posht-e-badam block, Central Iran, have been investigated to understand their provenance. Petrographical analysis suggests that the Lalun conglomerates are dominantly with chert clasts derived from a proximal source, probably chert bearing Precambrian Formations. Similarly, purple sandstones are classified as litharenite (chertarenite) and white sandstones as quartzarenite types. The detrital modes of purple and white sandstones indicate that they were derived from recycled orogen (uplifted shoulders of rift) and stable cratonic source. Most major and trace element contents of purple sandstones are generally similar to upper continental crust (UCC) values. However, white sandstones are depleted in major and trace elements (except SiO 2, Zr and Co) relative to UCC, which is mainly due to the presence of quartz and absence of other Al-bearing minerals. Shale samples have considerably lower content in most of the major and trace elements concentration than purple sandstones, which is possibly due to intense weathering and recycling. Modal composition (e.g., quartz, feldspar, lithic fragments) and geochemical indices (Th/Sc, La/Sc, Co/Th, Cr/Th, Cr/V and V/Ni ratios) of sandstones, and shales (La/Sc and La/Cr ratios) indicate that they were derived from felsic source rocks and deposited in a passive continental margin. The chondrite-normalized rare earth element (REE) patterns of the studied samples are characterized by LREE enrichment, negative Eu anomaly and flat HREE similar to an old upper continental crust composed chiefly of felsic components in the source area. The study of paleoweathering conditions based on modal composition, chemical index of alteration (CIA), plagioclase index of alteration (PIA) and A-CN-K (Al 2O 3 - CaO + Na 2O - K 2O) relationships indicate that probably chemical weathering in the source area and recycling processes have been more important in shale and white sandstones relative to purple sandstones. The results of this study suggest that the main source for the Lalun Formation was likely located in uplifted shoulders of a rifted basin (probably a pull-apart basin) in its post-rift stage (Pan-African basement of the Posht-e-badam block).

Reconstructing paleoceanographic conditions in the westernmost Mediterranean during the last 4.000 yr: tracking rapid climate variability

NASA Astrophysics Data System (ADS)

Nieto-Moreno, V.; Martínez-Ruiz, F.; Jiménez-Espejo, F. J.; Gallego-Torres, D.; Rodrigo-Gámiz, M.; Sakamoto, T.; Böttcher, M.; García-Orellana, J.; Ortega-Huertas, M.

2009-04-01

The westernmost Mediterranean (Alboran Sea basin) is a key location for paleoceanographic and paleoclimatic reconstructions since high sedimentation rates provide ultra high-resolution records at centennial and millennial scales. Here, we present a paleoenvironmental reconstruction for the last 4000 yr, which is based on a multi-proxy approach that includes major and trace element-content fluctuations and mineral composition of marine sediments. The investigated materials correspond to several gravity and box cores recovered in the Alboran Sea basin during different oceanographic cruises (TTR-14 and TTR-17), which have been sampled at very high resolution. Comparative analysis of these cores allows establishing climate oscillations at centennial to millennial scales. Although relatively more attention have been devoted to major climate changes during the last glacial cycle, such as the Last Glacial Maximun, deglaciation and abrupt cooling events (Heinrich and Younger Dryas), the late Holocene has also been punctuated by significant rapid climate variability including polar cooling, aridity and changes in the intensity of the atmospheric circulation. These climate oscillations coincide with significant fluctuations in chemical and mineral composition of marine sediments. Thus, bulk and clay mineralogy, REE composition and Rb/Al, Zr/Al, La/Lu ratios provide information on the sedimentary regime (eolian-fluvial input and source areas), Ba-based proxies on fluctuations in marine productivity and redox sensitive elements on oxygen conditions at time of deposition. A decrease in fluvial-derived elements/minerals (e.g., Rb, detrital mica) takes places during the so-called Late Bronze Age-Iron Age, Dark Age, and Little Ice Age Period. Meanwhile an increase is evidenced during the Medieval Warm Period and the Roman Humid Period. This last trend runs parallel to a decline of element/minerals of typical eolian source (Zr, kaolinite) with the exception of the Roman Humid Period where Zr/Al ratio increases. These climate oscillations (wet and dry periods) are also accompanied by changes in marine productivity rates, as suggested by the Ba/Al ratio. Additionally, anthropic contribution during the Industrial Period is also evidenced by a significant increase in Pb content in most recent sediments. Acknowledges: Projects Marcal CGL2006-13327-C04-04, Sagas CTM2005-08071-C03-01, Ministerio MARM 200800050084447, RNM 0179, CSD2006-00041.

Progressive enrichment of arc magmas caused by the subduction of seamounts under Nishinoshima volcano, Izu-Bonin Arc, Japan

NASA Astrophysics Data System (ADS)

Sano, Takashi; Shirao, Motomaro; Tani, Kenichiro; Tsutsumi, Yukiyasu; Kiyokawa, Shoichi; Fujii, Toshitsugu

2016-06-01

The chemical composition of intraplate seamounts is distinct from normal seafloor material, meaning that the subduction of seamounts at a convergent margin can cause a change in the chemistry of the mantle wedge and associated arc magmas. Nishinoshima, a volcanic island in the Izu-Bonin Arc of Japan, has been erupting continuously over the past 2 years, providing an ideal opportunity to examine the effect of seamount subduction on the chemistry of arc magmas. Our research is based on the whole-rock geochemistry and the chemistry of minerals within lavas and air-fall scoria from Nishinoshima that were erupted before 1702, in 1973-1974, and in 2014. The mineral phases within the analyzed samples crystallized under hydrous conditions (H2O = 3-4 wt.%) at temperatures of 970 °C-990 °C in a shallow (3-6 km depth) magma chamber. Trace element data indicate that the recently erupted Nishinoshima volcanics are much less depleted in the high field strength elements (Nb, Ta, Zr, Hf) than other volcanics within the Izu-Bonin Arc. In addition, the level of enrichment in the Nishinoshima magmas has increased in recent years, probably due to the addition of material from HIMU-enriched (i.e., high Nb/Zr and Ta/Hf) seamounts on the Pacific Plate, which is being subducted westwards beneath the Philippine Sea Plate. This suggests that the chemistry of scoria from Nishinoshima volcano records the progressive addition of components derived from subducted seamounts.

Purification of nuclear grade Zr scrap as the high purity dense Zr deposits from Zirlo scrap by electrorefining in LiF-KF-ZrF4 molten fluorides

NASA Astrophysics Data System (ADS)

Park, Kyoung Tae; Lee, Tae Hyuk; Jo, Nam Chan; Nersisyan, Hayk H.; Chun, Byong Sun; Lee, Hyuk Hee; Lee, Jong Hyeon

2013-05-01

Zirconium (Zr) has commonly been used as a cladding material of nuclear fuel. Moreover, it is regarded as the only material that can be used for nuclear fuel cladding because it has the lowest neutron capture cross section of any metal element and because it has high corrosion resistance and size stability. In this study, Hf-free Zr tubes (Zr-1Nb-1Sn-0.1Fe) were used as anode materials and electrorefining was performed in a LiF-KF eutectic 6 wt.% ZrF4 molten fluoride salt system. As a result of electrolysis, Zr scrap metal was recycled into pure Zr with low levels of impurities, and the size and density of the Zr deposit was controlled using applied current density.

Simultaneous quantification of 17 trace elements in blood by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) equipped with a high-efficiency sample introduction system.

PubMed

D'Ilio, S; Violante, N; Di Gregorio, M; Senofonte, O; Petrucci, F

2006-10-10

A quadrupole inductively coupled plasma mass spectrometer (Q-ICP-MS) equipped with a dynamic reaction cell (DRC) and coupled with a desolvating nebulization system (APEX-IR) was employed to determine 17 elements (Al, As, Ba, Cd, Co, Cr, Li, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, V, and Zr) in blood samples. Ammonia (for Al, Cr, Mn, and V) and O2 (for As and Se) were used as reacting gases. Selection of the best flow rate of the gases and optimization of the quadrupole dynamic bandpass tuning parameter (RPq) were carried out, using digested blood diluted 1+9 with deionized water and spiked with 1 microg L(-1) of Al, Cr, Mn, V and 5 microgL(-1) of As and Se. Detection limits were determined in digested blood using the 3sigma criterion. The desolvating system allowed a sufficient sensitivity to be achieved to determine elements at levels of ng L(-1) without detriment of signal stability. The accuracy of the method was tested with the whole blood certified reference material (CRM), certified for Al, As, Cd, Co, Cr, Mn, Mo, Ni, Pb, Sb, Se, and V, and with indicative values for Ba, Li, Sn, Sr, and Zr. The addition calibration approach was chosen for analysis. In order to confirm the DRC data, samples were also analyzed by means of sector field inductively coupled plasma mass spectrometry (SF-ICP-MS), operating in medium (m/Deltam=4000) and high (m/Deltam=10,000) resolution mode and achieving a good agreement between the two techniques.

pXRF quantitative analysis of the Otowi Member of the Bandelier Tuff: Generating large, robust data sets to decipher trace element zonation in large silicic magma chambers

NASA Astrophysics Data System (ADS)

Van Hoose, A. E.; Wolff, J.; Conrey, R.

2013-12-01

Advances in portable X-Ray fluorescence (pXRF) analytical technology have made it possible for high-quality, quantitative data to be collected in a fraction of the time required by standard, non-portable analytical techniques. Not only do these advances reduce analysis time, but data may also be collected in the field in conjunction with sampling. Rhyolitic pumice, being primarily glass, is an excellent material to be analyzed with this technology. High-quality, quantitative data for elements that are tracers of magmatic differentiation (e.g. Rb, Sr, Y, Nb) can be collected for whole, individual pumices and subsamples of larger pumices in 4 minutes. We have developed a calibration for powdered rhyolite pumice from the Otowi Member of the Bandelier Tuff analyzed with the Bruker Tracer IV pXRF using Bruker software and influence coefficients for pumice, which measures the following 19 oxides and elements: SiO2, TiO2, Al2O3, FeO*, MnO, CaO, K2O, P2O5, Zn, Ga, Rb, Sr, Y, Zr, Nb, Ba, Ce, Pb, and Th. With this calibration for the pXRF and thousands of individual powdered pumice samples, we have generated an unparalleled data set for any single eruptive unit with known trace element zonation. The Bandelier Tuff of the Valles-Toledo Caldera Complex, Jemez Mountains, New Mexico, is divided into three main eruptive events. For this study, we have chosen the 1.61 Ma, 450 km3 Otowi Member as it is primarily unwelded and pumice samples are easily accessible. The eruption began with a plinian phase from a single source located near center of the current caldera and deposited the Guaje Pumice Bed. The initial Unit A of the Guaje is geochemically monotonous, but Units B through E, co-deposited with ignimbrite show very strong chemical zonation in trace elements, progressing upwards through the deposits from highly differentiated compositions (Rb ~350 ppm, Nb ~200 ppm) to less differentiated (Rb ~100 ppm, Nb ~50 ppm). Co-erupted ignimbrites emplaced during column collapse show similar trace element zonation. The eruption culminated in caldera collapse after transitioning from a single central vent to ring fracture vents. Ignimbrites deposited at this time have lithic breccias and chaotic geochemical profiles. The geochemical discrepancy between early and late deposits warrants detailed, high-resolution sampling and analysis in order to fully understand the dynamics behind zonation processes. Samples were collected from locations that circumvent the caldera and prepared and analyzed in the field and the laboratory with the pXRF. Approximately 2,000 pumice samples will complete this unprecedented data set, allowing detailed reconstruction of trace element zonation around all sides of the Valles Caldera. These data are then used to constrain models of magma chamber processes that produce trace element zonation and how it is preserved in the deposits after a catastrophic, caldera-forming eruption.

Environmental Effects on Zirconium Hydroxide Nanoparticles and Chemical Warfare Agent Decomposition: Implications of Atmospheric Water and Carbon Dioxide.

PubMed

Balow, Robert B; Lundin, Jeffrey G; Daniels, Grant C; Gordon, Wesley O; McEntee, Monica; Peterson, Gregory W; Wynne, James H; Pehrsson, Pehr E

2017-11-15

Zirconium hydroxide (Zr(OH) 4 ) has excellent sorption properties and wide-ranging reactivity toward numerous types of chemical warfare agents (CWAs) and toxic industrial chemicals. Under pristine laboratory conditions, the effectiveness of Zr(OH) 4 has been attributed to a combination of diverse surface hydroxyl species and defects; however, atmospheric components (e.g., CO 2 , H 2 O, etc.) and trace contaminants can form adsorbates with potentially detrimental impact to the chemical reactivity of Zr(OH) 4 . Here, we report the hydrolysis of a CWA simulant, dimethyl methylphosphonate (DMMP) on Zr(OH) 4 determined by gas chromatography-mass spectrometry and in situ attenuated total reflectance Fourier transform infrared spectroscopy under ambient conditions. DMMP dosing on Zr(OH) 4 formed methyl methylphosphonate and methoxy degradation products on free bridging and terminal hydroxyl sites of Zr(OH) 4 under all evaluated environmental conditions. CO 2 dosing on Zr(OH) 4 formed adsorbed (bi)carbonates and interfacial carbonate complexes with relative stability dependent on CO 2 and H 2 O partial pressures. High concentrations of CO 2 reduced DMMP decomposition kinetics by occupying Zr(OH) 4 active sites with carbonaceous adsorbates. Elevated humidity promoted hydrolysis of adsorbed DMMP on Zr(OH) 4 to produce methanol and regenerated free hydroxyl species. Hydrolysis of DMMP by Zr(OH) 4 occurred under all conditions evaluated, demonstrating promise for chemical decontamination under diverse, real-world conditions.

Production test IP-544-A, irradiation of 1.6% enriched thick walled single tube elements in KER-1 and 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kratzer, W.K.; Wise, M.J.

1962-12-12

The objective of this production test is to authorize the irradiation of coextruded Zr-2 jacketed thick walled 1.6% enriched tubular elements in KER loops 1 and 2 to evaluate the swelling behavior of fuel elements at high uranium temperatures Coextruded Zr-2 jacketed 1.6% enriched tubular fuel elements 1.79 inch OD, 0.97 inch ID, and 12 inches long will be irradiated KER loops 1 and 2 to exposures no greater than 2500 MWD/T.

NEUTRONIC REACTOR FUEL ELEMENT

DOEpatents

Shackleford, M.H.

1958-12-16

A fuel element possessing good stability and heat conducting properties is described. The fuel element comprises an outer tube formed of material selected from the group consisting of stainhess steel, V, Ti. Mo. or Zr, a fuel tube concentrically fitting within the outer tube and containing an oxide of an isotope selected from the group consisting of U/sup 235/, U/sup 233/, and Pu/sup 239/, and a hollow, porous core concentrically fitting within the fuel tube and formed of an oxide of an element selected from the group consisting of Mg, Be, and Zr.

The origin and evolution of r- and s-process elements in the Milky Way stellar disk

NASA Astrophysics Data System (ADS)

Battistini, Chiara; Bensby, Thomas

2016-02-01

Context. Elements heavier than iron are produced through neutron-capture processes in the different phases of stellar evolution. Asymptotic giant branch (AGB) stars are believed to be mainly responsible for elements that form through the slow neutron-capture process, while the elements created in the rapid neutron-capture process have production sites that are less understood. Knowledge of abundance ratios as functions of metallicity can lead to insight into the origin and evolution of our Galaxy and its stellar populations. Aims: We aim to trace the chemical evolution of the neutron-capture elements Sr, Zr, La, Ce, Nd, Sm, and Eu in the Milky Way stellar disk. This will allow us to constrain the formation sites of these elements, as well as to probe the evolution of the Galactic thin and thick disks. Methods: Using spectra of high resolution (42 000 ≲ R ≲ 65 000) and high signal-to-noise (S/N ≳ 200) obtained with the MIKE and the FEROS spectrographs, we determine Sr, Zr, La, Ce, Nd, Sm, and Eu abundances for a sample of 593 F and G dwarf stars in the solar neighborhood. The abundance analysis is based on spectral synthesis using one-dimensional, plane-parallel, local thermodynamic equilibrium (LTE) model stellar atmospheres calculated with the MARCS 2012 code. Results: We present abundance results for Sr (156 stars), Zr (311 stars), La (242 stars), Ce (365 stars), Nd (395 stars), Sm (280 stars), and Eu (378 stars). We find that Nd, Sm, and Eu show trends similar to what is observed for the α elements in the [X/Fe]-[Fe/H] abundance plane. For [Sr/Fe] and [Zr/Fe], we find decreasing abundance ratios for increasing metallicity, reaching sub-solar values at super-solar metallicities. [La/Fe] and [Ce/Fe] do not show any clear trend with metallicity, and they are close to solar values at all [Fe/H]. The trends of abundance ratios [X/Fe] as a function of stellar ages present different slopes before and after 8 Gyr. Conclusions: The rapid neutron-capture process is active early in the Galaxy, mainly in type-II supernovae from stars in the mass range 8-10 M⊙. Europium is almost completely produced by the r-process, but Nd and Sm show similar trends to Eu even if their s-process component is higher. Strontium and Zr are thought to be mainly produced by the s-process, but show significant enrichment at low metallicity that requires extra r-process production, which probably is different from the classical r-process. Finally, La and Ce are mainly produced via s-process from AGB stars in the mass range 2-4 M⊙, which can be seen by the decrease in [La/Eu] and [Ce/Eu] at [Fe/H] ≈ -0.5. The trend of [X/Fe] with age could be explained by considering that the decrease in [X/Fe] for the thick disk stars can be due to the decrease in type-II supernovae with time, meaning a reduced enrichment of r-process elements in the interstellar medium. In the thin disk, the trends are flatter, which is probably due to the main production from the s-process being balanced by Fe production from type-Ia supernovae. This paper includes data gathered with the 6.5 m Magellan Telescopes at the Las Campanas Observatory, Chile and the ESO 1.5-m, 2.2-m. and 3.6-m telescopes on La Silla, Chile (ESO Proposal ID 65.L-0019, 67.B-0108, 76.B-0416, 82.B-0610); and data from UVES Paranal Observatory Project (ESO DDT Program ID 266.D-5655).Full Tables 3 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A49

Chemistry and origin of minor and trace elements in vitrinite concentrates from a rank series from the eastern United States, England, and Australia

USGS Publications Warehouse

Lyons, P.C.; Palmer, C.A.; Bostick, N.H.; Fletcher, J.D.; Dulong, F.T.; Brown, F.W.; Brown, Z.A.; Krasnow, M.R.; Romankiw, L.A.

1989-01-01

A rank series consisting of twelve vitrinite concentrates and companion whole-coal samples from mined coal beds in the eastern United States, England, and Australia were analyzed for C, H, N, O, ash, and 47 trace and minor elements by standard elemental, instrumental neutron activation analysis (INAA), and direct-current-arc spectrographic (DCAS) techniques. The reflectance of vitrinite, atomic H:C and O:C, and ash-free carbon data were used to determine ranks that range from high-volatile C bituminous coal to meta-anthracite. A van Krevelen (atomic H:C vs. O:C) diagram of the vitrinite concentrates shows a smooth curve having its lowest point at H:C = 0.18 and O:C = 0.01. This improves the van Krevelen diagram by the addition of our vitrinite concentrate from meta-anthracite from the Narragansett basin of New England. Boron content (400-450 ppm) in two Illinois basin vitrinite concentrates was about an order of magnitude higher than B contents in other concentrates analyzed. We attribute this to marine origin or hydrothermal activity. The alkaline-earth elements Ca, Mg and Ba (DCAS) have higher concentrations in our vitrinite concentrates from bituminous coals of the Appalachian basin, than they do in vitrinite concentrates from the marine-roofed bituminous coals of the Illinois basin; therefore, a nonmarine origin for these alkaline-earth elements is postulated for the Appalachian basin coals. An ion-exchange mechanism due to high concentrations of these elements as ions in diagenetic water, but probably not recent ground water, may be responsible for the relatively high values of these elements in Appalachian concentrates. Higher concentrations of Ni and Cr in one of the English vitrinite concentrates and of Zr in the Australian concentrate probably indicate organic association and detrital influence, respectively. ?? 1989.

Variation in trace element content of magnetite crystallized from a fractionating sulfide liquid, Sudbury, Canada: Implications for provenance discrimination

NASA Astrophysics Data System (ADS)

Dare, Sarah A. S.; Barnes, Sarah-Jane; Beaudoin, Georges

2012-07-01

Laser ablation ICP-MS analysis has been applied to many accessory minerals in order to understand better the process by which the rock formed and for provenance discrimination. We have determined trace element concentrations of Fe-oxides in massive sulfides that form Ni-Cu-PGE deposits at the base of the Sudbury Igneous Complex in Canada. The samples represent the crystallization products of fractionating sulfide liquids and consist of early-forming Fe-rich monosulfide solution (MSS) cumulates and residual Cu-rich intermediate solid solution (ISS). This study shows that Fe-oxide geochemistry is a sensitive petrogenetic indicator for the degree of fractionation of the sulfide liquid and provides an insight into the partitioning of elements between sulfide and Fe-oxide phases. In addition, it is useful in determining the provenance of detrital Fe-oxide. In a sulfide melt, all lithophile elements (Cr, Ti, V, Al, Mn, Sc, Nb, Ga, Ge, Ta, Hf, W and Zr) are compatible into Fe-oxide. The concentrations of these elements are highest in the early-forming Fe-oxide (titanomagnetite) which crystallized with Fe-rich MSS. Upon the continual crystallization of Fe-oxide from the sulfide liquid, the lithophile elements gradually decrease so that late-forming Fe-oxide (magnetite), which crystallized from the residual Cu-rich liquid, is depleted in these elements. This behavior is in contrast with Fe-oxides that crystallized from a fractionating silicate melt, whereby the concentration of incompatible elements, such as Ti, increases rather than decreases. The behavior of the chalcophile elements in magnetite is largely controlled by the crystallization of the sulfide minerals with only Ni, Co, Zn, Mo, Sn and Pb present above detection limit in magnetite. Nickel, Mo and Co are compatible in Fe-rich MSS and thus the co-crystallizing Fe-oxide is depleted in these elements. In contrast, magnetite that crystallized later from the fractionated liquid with Cu-rich ISS is enriched in Ni, Mo and Co because Fe-rich MSS is absent. The concentrations of Sn and Pb, which are incompatible with Fe-rich MSS, are highest in magnetite that formed from the fractionated Cu-rich liquid. At subsolidus temperatures, ilmenite exsolved from titanomagnetite whereas Al-spinel exsolved from the cores of some magnetite, locally redistributing the trace elements. However, during laser ablation ICP-MS analysis of these Fe-oxides both the magnetite and its exsolution products are ablated so that the analysis represents the original magmatic composition of the Fe-oxide that crystallized from the sulfide melt.

Trace Element Partitioning Between low-Ca Pyroxene and Ultracalcic Liquids.

NASA Astrophysics Data System (ADS)

Pertermann, M.; Schmidt, M. W.; Pettke, T.

2003-12-01

Low-Ca pyroxene or pigeonite ( ˜0.25-0.35 Ca per formula unit, pfu) is an important residual phase during high temperature melting of refractory mantle (e.g., ankaramite formation). High-Ca cpx (>0.6-0.7 Ca pfu) may be residual to relatively low temperature melting of fertile mantle (MOR and OI), but the opx-cpx solvus narrows considerably at higher temperatures (>1330-1350° C), leading to coexisting opx and low-Ca cpx. Little is known about the trace element partitioning of such low-Ca cpx at upper mantle conditions. Our new partitioning experiments investigate the role of low-Ca cpx during melting of depleted peridotite. Nominally anhydrous experiments with graphite-lined Pt-capsules were conducted at 1.4 GPa and 1360-1370° C. The synthetic starting material is close in composition to an ultracalcic liquid saturated in opx+pigeonite+olivine+spinel. The experiments yielded assemblages of glass, low-Ca cpx, ol, and minor Cr-spinel; opx is absent. The low-Ca clinopyroxenes have 0.20 and 0.32 Ca pfu at 1370 and 1360° C, respectively, and tetrahedral Al of 0.046 and 0.067 pfu. The liquids have ˜50 wt% SiO2, ˜12.5 wt% CaO and CaO/Al2O3 of 1.44-1.54. Pyroxenes and glasses were analyzed for trace elements (La, Ce, Nd, Sm, Eu, Gd, Dy, Er Yb, Lu, Sc, Y, Sr, Zr, Hf, V, Cr, Mn, Co, Zn) by LA-ICP-MS using a 193 nm ArF excimer laser coupled to an Elan 6100 mass spectrometer. Ablation occurred in He, and ablation spot sizes were 15-30 μ m for minerals and 50 μ m for glasses. Trace element concentrations in pyroxenes were low for most 3+ and 4+ cations. This resulted in small mineral/melt partition coefficients (D-values), approximately an order of magnitude lower than those for high-Ca cpx associated with peridotite melting, thus making the low-Ca cpx partitioning behavior rather similar to the behavior of peridotitic opx. Cpx with 0.32 Ca pfu has slightly elevated D-values for 3+ cations when compared to the 0.20 Ca pfu cpx: DSc = 0.45, DY = 0.11, DSm = 0.054 and DYb = 0.141, compared to values of 0.32, 0.065, 0.016 and 0.075, respectively. Regardless of Ca content, V, Mn, Co and Zn are mildly incompatible (Ds ˜0.5-0.9). Therefore, only Sc, V, Cr, Mn, Co, Ni and Zn are retained during partial mantle melting with a pigeonite+opx+ol residue. Most other elements partition strongly into the melt, and barring exotic residual minerals, the composition of ultracalcic liquids reflects the incompatible trace element budget of the depleted peridotite source.

Geochemical constraints on provenance of the mid-Pleistocene red earth sediments in subtropical China

NASA Astrophysics Data System (ADS)

Hong, Hanlie; Wang, Chaowen; Zeng, Kefeng; Gu, Yansheng; Wu, Yuanbao; Yin, Ke; Li, Zhaohui

2013-05-01

The source of mid-Pleistocene red earth sediments in the middle to lower reaches of the Yangtze (Changjiang) River was investigated based on their geochemical characteristics. The Xuancheng and Jiujiang red earth sediments have similar major and trace element distribution patterns. Compared to the loess and paleosol deposits of the Chinese Loess Plateau, the upper continental crust (UCC), and the post-Archean Australian average shale (PAAS), the sediments display notable depletion of CaO, MgO, Na2O, and accumulation of TiO2, Al2O3, and Fe2O3(t). The trace element distribution patterns of the red earth sediments are also different from those of loess and the PAAS, but are similar to those of the loess deposits, except for lower values of mobile trace elements Sr, Ba, and Ni, and higher values of Zr and Y. The red earth samples have uniform La/Th ratios of ~ 2.8, compatible with those of the UCC, loess, and paleosol. They also have similar chondrite-normalized REE patterns, characterized by enriched LREE and relatively flat HREE profiles, and consistent negative Eu anomalies, similar to those of the UCC, the loess and paleosol, and the Yangtze deposits. These results suggest that the red earth sediments have been subject to considerable mixing prior to deposition and strong subsequent chemical weathering. The sediments have very uniform 143Nd/144Nd and 147Sm/144Nd ratios, this points to well-mixed and multi-recycled sediments. The 143Nd/144Nd and 87Sr/86Sr values of the red earth sediments match well with those of the deposits in the middle to lower reaches of the Yangtze River, but are different from those of the loess and paleosols. This suggests that the red earth sediments are derived from the drainage basins of the middle to lower Yangtze River and might have experienced more intense chemical weathering relative to the Yangtze deposits, as reflected by their higher Rb/Sr ratios, intense depletion of mobile elements and accumulation of immobile elements, as well as their well-developed net-like structure.

Constraints on Hf and Zr mobility in high-sulfidation epithermal systems: formation of kosnarite, KZr2(PO4)3, in the Chaquicocha gold deposit, Yanacocha district, Peru

NASA Astrophysics Data System (ADS)

Deditius, Artur P.; Utsunomiya, Satoshi; Sanchez-Alfaro, Pablo; Reich, Martin; Ewing, Rodney C.; Kesler, Stephen E.

2015-04-01

We report the first occurrence of Hf-rich kosnarite [K(Hf,Zr)2(PO4)3], space group R- 3c, Z = 6, in the giant Chaquicocha high-sulfidation epithermal gold deposit in the Yanacocha mining district, Peru. Kosnarite crystals are small (<100 μm) and occur in 2-3-mm-thick veins that cut intensively silicified rocks. The paragenesis includes a first stage of As-free pyrite and quartz (plus gratonite and rutile), followed by trace metal-rich pyrite [(Fe,As,Pb,Au)S2] and secondary Fe sulfates. Kosnarite is associated with quartz and is clearly late within the paragenetic sequence. Electron microprobe analyses (EMPA) of kosnarite show relatively high concentrations of HfO2 and Rb2O (7.61 and 1.05 wt.%, respectively). The re-calculated chemical formulas of kosnarite vary from KΣ1.00(Zr1.93Na0.01Hf0.01Mn0.01)Σ1.96(P3.04O4)Σ3 to (K0.92Rb0.05Na0.03)Σ1.00(Zr1.81Hf0.19)Σ2.00 [(P2.98Si0.02As0.01)Σ3.01O4]Σ3, where Hf and Rb are most likely incorporated according to a coupled substitution of Hf4+ + Rb+ ⇔ Zr4+ + K+. Back-scattered electron (BSE) images and elemental mapping of kosnarite reveal that Hf and Rb are enriched in 2-10-μm-wide oscillatory and/or sector zones. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) observations of such zones reveal a pattern of alternating, 5-50-nm-thick, Hf-rich and Zr-rich nanozones. These high-resolution observations indicate that the incorporation of Hf does not appear to cause significant distortion in the kosnarite structure. Semiquantitative TEM-energy-dispersive X-ray spectrometry (EDS) analyses of the nano-layers show up to 22 wt.% of HfO2, which corresponds to 31 mol% of the hypothetical, KHf2(PO4)3, end-member. The presence of kosnarite in the advanced argillic alteration zone at Yanacocha is indicative of Hf and Zr mobility under highly acidic conditions and points towards an unforeseen role of phosphates as sinks of Zr and Hf in high-sulfidation epithermal environments. Finally, potentially new geochronological applications of highly insoluble vein kosnarite, including Rb-Sr dating, may provide further age constraints in pervasively altered areas where other isotopic systems might have been reset.

Silica-coated titania and zirconia colloids for subsurface transport field experiments

USGS Publications Warehouse

Ryan, Joseph N.; Elimelech, Menachem; Baeseman, Jenny L.; Magelky, Robin D.

2000-01-01

Silica-coated titania (TiO2) and zirconia (ZrO2) colloids were synthesized in two sizes to provide easily traced mineral colloids for subsurface transport experiments. Electrophoretic mobility measurements showed that coating with silica imparted surface properties similar to pure silica to the titania and zirconia colloids. Measurements of steady electrophoretic mobility and size (by dynamic light scattering) over a 90-day period showed that the silica-coated colloids were stable to aggregation and loss of coating. A natural gradient field experiment conducted in an iron oxide-coated sand and gravel aquifer also showed that the surface properties of the silica-coated colloids were similar. Colloid transport was traced at μg L-1 concentrations by inductively coupled plasma-atomic emission spectroscopy measurement of Ti and Zr in acidified samples.

Investigating Alpine fissure rutilated quartz to constrain timing and conditions of post-metamorphic hydrothermal fluid flow

NASA Astrophysics Data System (ADS)

Shulaker, D. Z.; Schmitt, A. K.; Zack, T.; Bindeman, I. N.

2013-12-01

Rutilated quartz, aka Venus' hair, is finely-acicular rutile intergrown with host quartz generated by fluid-mediated co-crystallization. It is commonly found in hydrothermal veins, including the renown cleft mineral locations of the Swiss Alps. Previous studies of Alpine cleft mineralizations used rare hydrothermal monazite [1] and titanite [2] to constrain vein formation to ~13.5-15.2 Ma, postdating peak metamorphism by ~2-4 Ma. Temperature (T) estimates of 150-450°C are based on fluid inclusions and bulk quartz-mineral oxygen isotope exchange equilibria, and formation pressures (P) are 0.5-2.5 kbar (for a geothermal gradient of 30°C/km) [2]. The potential of rutilated quartz as a thermochronometer, however, has not been harnessed previously. Here, we present the first results of age and P-T determinations for rutilated quartz from six locations in the Swiss Alps (San Gottardo; Feldbach, Binntal; Pi Aul, Vals; Faido, Leventina; Elm, Steinbach; Binntal). Samples were cut and mounted in epoxy discs to expose rutile (0.03 to 1 mm in diameter) and its host quartz which was also imaged in cathodoluminescence (CL). CL images for half of the samples' host quartz exhibited strong sector zoning, while others reveal only weak CL zonation. Isotopic and trace element analyses were carried out by SIMS using a CAMECA ims1270 for U-Pb, O-isotopes, and Ti-in-quartz, and a LA-ICP-MS system (213 nm New Wave laser coupled to an Agilent 7500a) for Zr-in-rutile. U-Pb rutile ages average 15.5×2.0 Ma (2σ). T estimates are 352-575°C (rutile-quartz oxygen isotopes in touching domains), 470-530°C (Zr-in-rutile assuming P = 0.5 and equilibrium with host-rock zircon), and 251-391°C (Ti-in-quartz at assumed P = 0.5 kbar and aTiO2 = 1). CL zones are isotopically unzoned. Rutile-quartz oxygen isotopes are pressure insensitive, whereas Zr-in-rutile and Ti-in-quartz are minimum temperatures. These results demonstrate that rutilated quartz can constrain timing and conditions of post-metamorphic hydrothermal fluid flow and mineralization. Discrepancies in thermometers are attributed to differences between experimental calibrations of isotopic and trace element thermometers, and the conditions of post-metamorphic hydrothermal fluid flow. Only rutile-quartz oxygen isotope exchange [3] has been calibrated close to natural T conditions for rutilated quartz (500°C). This may help to extend the applicability of the Ti-in-quartz and Zr-in-rutile to T below experimental calibrations (>600°C; [4] and >700°C; [5], resp.). [1] Janots et al., 2012, Chem. Geol., 326-327, 61-71 [2] Mullis, 1996, Schweiz. Mineral. Petrogr. Mitt., 76, 159-164 [3] Matthews, 1994, J. Met. Geol., 12, 211-219 [4] Thomas et al., 2010, Contrib. Mineral. Petrol., 160, 743-759 [5] Ferry and Watson, 2007, Contrib. Mineral. Petrol., 154, 429-437

Determination of refractive and volatile elements in sediment using laser ablation inductively coupled plasma mass spectrometry.

PubMed

Duodu, Godfred Odame; Goonetilleke, Ashantha; Allen, Charlotte; Ayoko, Godwin A

2015-10-22

Wet-milling protocol was employed to produce pressed powder tablets with excellent cohesion and homogeneity suitable for laser ablation (LA) analysis of volatile and refractive elements in sediment. The influence of sample preparation on analytical performance was also investigated, including sample homogeneity, accuracy and limit of detection. Milling in volatile solvent for 40 min ensured sample is well mixed and could reasonably recover both volatile (Hg) and refractive (Zr) elements. With the exception of Cr (-52%) and Nb (+26%) major, minor and trace elements in STSD-1 and MESS-3 could be analysed within ±20% of the certified values. Comparison of the method with total digestion method using HF was tested by analysing 10 different sediment samples. The laser method recovers significantly higher amounts of analytes such as Ag, Cd, Sn and Sn than the total digestion method making it a more robust method for elements across the periodic table. LA-ICP-MS also eliminates the interferences from chemical reagents as well as the health and safety risks associated with digestion processes. Therefore, it can be considered as an enhanced method for the analysis of heterogeneous matrices such as river sediments. Copyright © 2015 Elsevier B.V. All rights reserved.

A Priori Method of Using Photon Activation Analysis to Determine Unknown Trace Element Concentrations in NIST Standards

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, Jaromy; Sun Zaijing; Wells, Doug

2009-03-10

Photon activation analysis detected elements in two NIST standards that did not have reported concentration values. A method is currently being developed to infer these concentrations by using scaling parameters and the appropriate known quantities within the NIST standard itself. Scaling parameters include: threshold, peak and endpoint energies; photo-nuclear cross sections for specific isotopes; Bremstrahlung spectrum; target thickness; and photon flux. Photo-nuclear cross sections and energies from the unknown elements must also be known. With these quantities, the same integral was performed for both the known and unknown elements resulting in an inference of the concentration of the un-reported elementmore » based on the reported value. Since Rb and Mn were elements that were reported in the standards, and because they had well-identified peaks, they were used as the standards of inference to determine concentrations of the unreported elements of As, I, Nb, Y, and Zr. This method was tested by choosing other known elements within the standards and inferring a value based on the stated procedure. The reported value of Mn in the first NIST standard was 403{+-}15 ppm and the reported value of Ca in the second NIST standard was 87000 ppm (no reported uncertainty). The inferred concentrations were 370{+-}23 ppm and 80200{+-}8700 ppm respectively.« less

Characterization of Ultra-high Temperature Ceramics via Transmission Electron Microscopy Relevant ZrB2-based Composites, TaC-based Composites and Oxides Containing SiC Chopped Fibers

DTIC Science & Technology

2015-03-06

was formed by ZrO2 rounded grains containing W traces and covered by H3BO3 acicular crystals deriving from hydration of B2O3 after exposure to...TaSi2 grains tended to form large pockets as wide as 3-8 m. Other spurious phases formed upon decomposition of the additive, were identified as SiC

Petrology of basalts from Loihi Seamount, Hawaii

NASA Astrophysics Data System (ADS)

Hawkins, James; Melchior, John

1983-12-01

Loihi Seamount is the southeasternmost active volcano of the Emperor-Hawaii linear volcanic chain. It comprises a spectrum of basalt compositional varieties including basanite, alkali basalt, transitional basalt and tholeiite. Samples from four dredge collections made on Scripps Institution of Oceanography Benthic Expedition in October 1982 are tholeiite. The samples include highly vesicular, olivine-rich basalt and dense glass-rich pillow fragments containing olivine and augite phenocrysts. Both quartz-normative and olivine-normative tholeiites are present. Minor and trace element data indicate relatively high abundances of low partition coefficient elements (e.g., Ti, K, P. Rb, Ba, Zr) and suggest that the samples were derived by relatively small to moderate extent of partial melting, of an undepleted mantle source. Olivine composition, MgO, Cr and Ni abundances, and Mg/(Mg+Fe), are typical of moderately fractionated to relatively unfractionated "primary" magmas. The variations in chemistry between samples cannot be adequately explained by low-pressure fractional crystallization but can be satisfied by minor variations in extent of melting if a homogeneous source is postulated. Alternatively, a heterogeneous source with variable abundances of certain trace elements, or mixing of liquids, may have been involved. Data for 3He/ 4He, presented in a separate paper, implies a mantle plume origin for the helium composition of the Loihi samples. There is little variation in the helium isotope ratio for samples having different compositions and textures. The helium data are not distinctive enough to unequivocally separate the magma sources for the tholeiitic rocks from the other rock types such as Loihi alkalic basalts and the whole source region for Loihi may have a nearly uniform helium compositions even though other element abundances may be variable. Complex petrologic processes including variable melting, fractional crystallization and magma mixing may have blurred original helium isotopic signatures.

Am phases in the matrix of a U–Pu–Zr alloy with Np, Am, and rare-earth elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janney, Dawn E.; Kennedy, J. Rory; Madden, James W.

2015-01-01

Phases and microstructures in the matrix of an as-cast U-Pu-Zr alloy with 3 wt% Am, 2% Np, and 8% rare-earth elements were characterized by scanning and transmission electron microscopy. The matrix consists primarily of two phases, both of which contain Am: ζ-(U, Np, Pu, Am) (~70 at% U, 5% Np, 14% Pu, 1% Am, and 10% Zr) and δ-(U, Np, Pu, Am)Zr 2 (~25% U, 2% Np, 10-15% Pu, 1-2% Am, and 55-60 at% Zr). These phases are similar to those in U-Pu-Zr alloys, although the Zr content in ζ-(U, Np, Pu, Am) is higher than that in ζ-(U, Pu)more » and the Zr content in δ-(U, Np, Pu, Am)Zr 2 is lower than that in δ-UZr 2. Nanocrystalline actinide oxides with structures similar to UO2 occurred in some areas, but may have formed by reactions with the atmosphere during sample handling. Planar features consisting of a central zone of ζ-(U, Np, Pu, Am) bracketed by zones of δ-(U, Np, Pu, Am)Zr 2 bound irregular polygons ranging in size from a few micrometers to a few tens of micrometers across. The rest of the matrix consists of elongated domains of ζ-(U, Np, Pu, Am) and δ-(U, Np, Pu, Am)Zr 2. Each of these domains is a few tens of nanometers across and a few hundred nanometers long. The domains display strong preferred orientations involving areas a few hundred nanometers to a few micrometers across.« less

Growth and microstructure formation of isothermally-solidified Zircaloy-4 joints brazed by a Zr-Ti-Cu-Ni amorphous alloy ribbon

NASA Astrophysics Data System (ADS)

Kim, K. H.; Lim, C. H.; Lee, J. G.; Lee, M. K.; Rhee, C. K.

2013-10-01

The microstructure and growth characteristics of Zircaloy-4 joints brazed by a Zr48Ti16Cu17Ni19 (at.%) amorphous filler metal have been investigated with regard to the controlled isothermal solidification and intermetallic formation. Two typical joints were produced depending on the isothermal brazing temperature: (1) a dendritic growth structure including bulky segregation in the central zone (at 850 °C), and (2) a homogeneous dendritic structure throughout the joint without segregation (at 890 °C). The primary α-Zr phase was solidified isothermally, nucleating to grow into a joint with a cellular or dendritic structure. Also, the continuous Zr2Ni and particulate Zr2Cu phases were formed in the segregated center zone and at the intercellular region, respectively, owing to the different solubility and atomic mobility of the solute elements (Ti, Cu, and Ni) in the α-Zr matrix. A disappearance of the central Zr2Ni phase was also rate-controlled by the outward diffusion of the Cu and Ni elements. When the detrimental Zr2Ni intermetallic phase was eliminated by a complete isothermal solidification at 890 °C, the strengths of the joints were high enough to cause yielding and fracture in the base metal, exceeding those of the bulk Zircaloy-4, at room temperature as well as at elevated temperatures (up to 400 °C).

Laser diagnostics for NTP fuel corrosion studies

NASA Technical Reports Server (NTRS)

Wantuck, Paul J.; Butt, D. P.; Sappey, A. D.

1993-01-01

Viewgraphs and explanations on laser diagnostics for nuclear thermal propulsion (NTP) fuel corrosion studies are presented. Topics covered include: NTP fuels; U-Zr-C system corrosion products; planar laser-induced fluorescence (PLIF); utilization of PLIF for corrosion product characterization of nuclear thermal rocket fuel elements under test; ZrC emission spectrum; and PLIF imaging of ZrC plume.

Differentiating Metamorphic Events in a Polymetamorphic Terrane using Zr-in-Ttn thermometry and Titanite U-Pb Geochronology

NASA Astrophysics Data System (ADS)

Kenney, M.; Roeske, S.; Mulcahy, S. R.; Cottle, J. M.; Coble, M. A.

2016-12-01

In polymetamorphic terranes, it is problematic to link ages from geochronometers to metamorphic fabrics and, therefore, to a specific deformation event(s). It is necessary to analyze a mineral which may preserve multiple age domains. Titanite has been shown to retain multiple age and elemental domains in single grains through high-grade metamorphism. In this study, titanite U-Pb geochronology is used to examine whether ages are thermally reset along a sample transect towards a mylonitic shear zone in NW Argentina. This work also seeks to understand the conditions under which titanite resists resetting. A combination of petrographic and electron microprobe analyses reveal the textures and compositional domains in titanite, garnet, and hornblende. Titanite are elongate, wrapped by the mylonitic fabric, and have patchy elemental zoning. Garnet has distinct cores with prograde zoning and thin rims, which appear to be in equilibrium with the fabric defining minerals. Hornblende has inclusion rich cores and thin overgrowth rims in equilibrium with the fabric defining minerals. In-situ U-Pb and trace element data was collected in titanite from four samples, which all preserve lower-intercept ages between 900Ma and 1.0Ga. We observed no correlation between age and elemental domains; these domains correlate with Al and Nb variations. Zr-in-titanite temperatures preserve upper amphibolite facies conditions, 660ºC-710ºC. Given these results, we conclude that titanite U-Pb ages and temperatures reflect original Grenville metamorphism. 40Ar/39Ar hornblende cooling ages, of 515 Ma, suggested titanite may be reset near the shear zone but overprinting P-T of 560ºC and 0.8 GPa, fluid infiltration, and deformation did not cause significant Pb loss. Overprinting conditions and cooling ages suggest that rims of garnet and hornblende correlate to Paleozoic metamorphism, while textural evidence and titanite ages suggest garnet and hornblende cores grew during the Proterozoic.

Countrywide Reassessment of Schistosoma mansoni Infection in Burundi Using a Urine-Circulating Cathodic Antigen Rapid Test: Informing the National Control Program

PubMed Central

Ortu, Giuseppina; Ndayishimiye, Onésime; Clements, Michelle; Kayugi, Donatien; Campbell, Carl H.; Lamine, Mariama Sani; Zivieri, Antonio; Magalhaes, Ricardo Soares; Binder, Sue; King, Charles H.; Fenwick, Alan; Colley, Daniel G.; Jourdan, Peter Mark

2017-01-01

Following implementation of the national control program, a reassessment of Schistosoma mansoni prevalence was conducted in Burundi to determine the feasibility of moving toward elimination. A countrywide cluster-randomized cross-sectional study was performed in May 2014. At least 25 schools were sampled from each of five eco-epidemiological risk zones for schistosomiasis. Fifty randomly selected children 13–14 years of age per school were included for a single urine-circulating cathodic antigen (CCA) rapid test and, in a subset of schools, for duplicate Kato-Katz slide preparation from a single stool sample. A total of 17,331 children from 347 schools were tested using CCA. The overall prevalence of S. mansoni infection, when CCA trace results were considered negative, was 13.5% (zone range [zr] = 4.6–17.8%), and when CCA trace results were considered positive, it was 42.8% (zr = 34.3–49.9%). In 170 schools, prevalence of this infection determined using Kato-Katz method was 1.5% (zr ==0–2.7%). The overall mean intensity of S. mansoni infection determined using Kato-Katz was 0.85 eggs per gram (standard deviation = 10.86). A majority of schools (84%) were classified as non-endemic (prevalence = 0) using Kato-Katz; however, a similar proportion of schools were classified as endemic when CCA trace results were considered negative (85%) and nearly all (98%) were endemic when CCA trace results were considered positive. The findings of this nationwide reassessment using a CCA rapid test indicate that Schistosoma infection is still widespread in Burundi, although its average intensity is probably low. Further evidence is now needed to determine the association between CCA rapid test positivity and low-intensity disease transmission. PMID:28115675

The Experimental Study of Nuclear Astrophysics Reaction Rate of 93Zr(n,γ)94Zr

NASA Astrophysics Data System (ADS)

Gan, L.; Li, Z. H.; Su, J.; Yan, S. Q.; Guo, B.; Du, X. C.; Wu, Z. D.; Zeng, S.; Jin, S. J.; Wang, Y. B.; Bai, X. X.; Zhang, W. J.; Sun, H. B.; Li, E. T.

The slow neutron capture (s-) process plays a very important role in the nucleosynthesis, which produces about half of the elements heavier than iron. 94Zr is mainly from 93Zr(n,γ)94Zr in the s-process, and the direct component of the 93Zr(n,γ)94Zr capture reaction can be derived from the neutron spectroscopic factor of 94Zr. As the existing neutron spectroscopic factors of 94Zr vary from each other up to 60%, a new work should be adopted to measure it exactly. In the present work, the angular distributions of 94Zr(13C,13C)94Zr, 94Zr(12C,12C)94Zr and 94Zr(12C,13C)93Zr were obtained using the highprecision Q3D magnetic spectrograph. In addition, distorted-wave Born approximation (DWBA) calculations of the transfer differential cross sections were performed. The calculated result displays a good agreement with the experiment data, and a value of 2.60±0.20 for the neutron spectroscopic factor of 94Zr was extracted, and the direct capture cross section versus neutron energy of 93Zr(n,γ)94Zr for the ground state of 94Zr was obtained too.

Drastic shift of lava geochemistry between pre- and post- Japan Sea opening in NE Japan subduction zone: constraints on source composition and slab surface melting processes

NASA Astrophysics Data System (ADS)

Okamura, S.; Inaba, M.; Igarashi, S.; Aizawa, M.; Shinjo, R.

2017-12-01

Isotopic and trace element data imply a temporal change in magma sources and thermal conditions beneath the northern Fossa Magna, NE Japan arc from the Oligocene to the Pleistocene. Less radiogenic 176Hf/177Hf and 143Nd/144Nd, and high Zr/Hf characterize the Oligocene - Early Miocene volcanism in the northern Fossa Magna region. The mantle wedge in the Oligocene - Early Miocene consisted of enriched mantle source. We propose that during the onset of subduction, influx of hot asthenospheric mantle provided sufficient heat to partially melt newly subducting sediment. Geochemical modeling results suggest breakdown of zircon in the slab surface sediments for the Oligocene - Early Miocene lavas in the northern Fossa Magna region. In the Middle Miocene, the injection of hot and depleted asthenospheric material replaced the mantle beneath the northern Fossa Magna region of NE Japan. The Middle Miocene lavas characterized by most radiogenic Hf and Nd isotope ratios, have high Zr/Hf. An appropriate working petrogenetic model is that the Middle Miocene lavas were derived from asthenospheric depleted mantle, slightly (<1%) contaminated by slab melt accompanied by full dissolution of zircon. All the Late Miocene - Pleistocene samples are characterized by distinctly more radiogenic 176Hf/177Hf and 143Nd/144Nd, and are displaced toward lower Zr/Hf, which requires mixing between depleted mantle and a partial melt of subducted metasediment saturated with trace quantity of zircon. The Oligocene - Early Miocene volcanism in the northern Fossa Magna region may represent the early stage of continental margin magmatism associated with a back-arc rift. Here volcanism is dominated by sediment melts. Perhaps asthenospheric injection, triggering Japan Sea opening, allowed higher temperatures and more melting at the slab-mantle interface. The mantle wedge was gradually cooled during the Middle Miocene to the Pleistocene with back-arc opening ending in the Late Miocene. Slab surface temperatures were still high enough for sediments to melt but not too high (< 780 °C) to lose zircon as a residual phase.

Trace element behavior and P-T-t evolution during partial melting of exhumed eclogite in the North Qaidam UHPM belt (NW China): Implications for adakite genesis

NASA Astrophysics Data System (ADS)

Zhang, Guibin; Niu, Yaoling; Song, Shuguang; Zhang, Lifei; Tian, Zuolin; Christy, Andrew G.; Han, Lei

2015-06-01

We have studied trace element behavior and timing of decompression melting of UHP rocks during exhumation recorded in the magmatic products, i.e., the melt phase (leucosomes), cumulate (garnetite) and residue (amphibolitized eclogite) from a single outcrop in the south Dulan area, North Qaidam UHPM belt, NW China. Two distinct episodes of partial melting are recognized. First, Grt-free tonalitic-trondhjemitic leucosome melts with higher silica crystallized at 424.0 ± 2.7 Ma. Garnets grew in the leucosome melt but fractionated out to form garnetite cumulates along with Ti-rich phases (rutile and titanite), strengthening the adakitic signature of the leucosome. Later Grt-bearing leucosome melts with an age of 412.4 ± 2.9 Ma cross-cut boudins and layers of amphibolitized eclogite. Geochemical investigation of bulk-rocks and in situ minerals verifies the genetic relationship between the amphibolitized eclogite and the tonalitic-trondhjemitic melts. Zircons from the amphibolitized eclogite have older (> 700 Ma) protolith ages, with subsequent eclogite-facies metamorphism, retrograde granulite-facies overprinting and partial melting. Phase modeling and Zr-in-rutile thermometry calculations in combination with zircon geochronology reveal the evolution P-T-t path for the exhumation and the partial melting of the deeply subducted continental crust at the North Qaidam subduction zone in the Early Paleozoic.

Geochemistry of organic carbon and trace elements in boreal stratified lakes during different seasons

NASA Astrophysics Data System (ADS)

Moreva, O. Y.; Pokrovsky, O. S.; Shirokova, L. S.; Viers, J.

2008-12-01

Our knowledge of chemical fluxes in the system rock-soils-rivers-ocean of boreal and glacial landscapes is limited by the least studied part, i.e., the river water transformation between the lake and the river systems. Dissolved organic carbon (DOC), nutrients, major and trace elements are being leached from soil profile to the river but subjected to chemical transformation in the lakes due to phytoplankton and bacterial activity. As a result, many lakes in boreal regions are quite different in chemical composition compared to surrounding rivers and demonstrate important chemical stratification. The main processes responsible for chemical stratification in lakes are considered to be i) diffusion fluxes from the sediment to the bottom water accompanied by sulfate reduction and methanogenesis in the sediments and ii) dissolution/mineralization of precipitating organic matter (mineral fraction, detritus, plankton pellets) in the bottom layer horizons under anoxic conditions. Up to present time, distinguishing between two processes remains difficult. This paper is aimed at filling this gap via detailed geochemical analysis of DOC and trace elements in the water column profiles of three typical stratified lakes of Arkhangelsk region in Kenozersky National Parc (64° N) in winter (glacial) and in summer period. Concentration of most trace elements (Li, B, Al, Ti, V, Cr, Ni, Co, Zn, As, Rb, Sr, Y, Zr, Mo, Sb, Ba, REEs, Th, U) are not subjected to strong variations along the water column, despite the presence of strong or partial redox stratification. Apparently, these elements are not significantly controlled by production/mineralization processes and redox phenomena in the water column, or the influence of these processes is not pronounced under the control by the allochtonous river water input. In particularly, the stability of titanium and aluminum concentration along the depth profile and their independence of iron behavior suggest the important control by dissolved organic matter. Therefore, organo-ferric colloids controlling petrogenic elements speciation in soil and river waters are being replaced by autochthonous organic colloids in the lake system. The same observation is true for some heavy metals such as nickel, copper and zinc, whereas cobalt, as limiting component, is being strongly removed from the photic zone or it is coprecipitating with manganese hydroxide. Results of the present work allow quantitative evaluation of the role of redox processes in the bottom horizons and organic detritus degradation in the creation of chemical stratification of small lakes with high DOC concentration. Further insights on geochemical migration of trace elements in lakes require : i) study of colloidal speciation using in-situ dialysis; ii) monitoring the annual and seasonal dynamics of redox processes and TE concentration variation along the profile; iii) quantitative assessment of bacterial degradation of suspended OM and Mn and Fe redox reactions along the depth profile; iv) setting the sedimentary traps for evaluation of suspended material fluxes, and, v) thorough study of chemical composition of interstitial pore waters.

Multistage metasomatism in lithospheric mantle beneath V. Grib pipe (Arkhangelsk diamondiferous province, Russia): evidence from REE patterns in garnet xenocrysts.

NASA Astrophysics Data System (ADS)

Shchukina, Elena; Alexei, Agashev; Nikolai, Pokhilenko

2015-04-01

150 garnet xenocrysts from V. Grib kimberlite pipe were analyzed for major and trace elements compositions. 70 % of garnet belong to lherzolite field; 14 % - megacrysts and pyroxenites; 11 % - eclogites; 4 % - harzburgite; 1 % (1- wehrlite defined by Sobolev (1973). Harzburgite garnets: sinusoidal REE patterns Smn/Ern > 5 (5.2 - 19.8). low Y (0.5 - 3.9 ppm), Zr (1.1 - 44.6 ppm), Ti (54 - 1322 ppm). Wehrlite garnetd: close to sinusoidal REE patterns, Smn/Ern - 1.8. Megacrysts and pyroxenites garnets: normal REE patterns Smn/Ern < 1 (0.2 - 0.6), high TiO2 (0.9 - 1.3 wt %). Lherzolite garnets 70 % show four groups of REE patterns similar to peridotite xenoliths (Shchukina et al., 2013, 2015). 1-st contains MREE at С1 level, Sm/Ern - 0.03, La/Ybn - 0.002. increasing La -Yb range, low Y, Zr, Ti indicating residual nature. 2-nd: MREE at 2 - 13 chondrite units, Smn/Ern (0.16 - 0.98), La/Ybn - 0.001 - 0.040 and flat pattern from MREE to HREE. 3-rd -MREE at 5 - 14 chondrite units, Sm/Ern > 1 (1.05 - 4.81) La/Ybn - 0.010-0.051 increasing an hump at MREE decreasing to HREE. 4-th: sinusoidal REE, Sm/Ern 4.2 - 27.2. and harzburgite Y, Zr, Ti . Average Cr2O3 content increases from 2-nd to the 3-rd group (3.3 to 5.7 wt%) and 4th (7.9 wt %). Average Y/Zr decreases from 2-nd (0.6) to 3rd (0.2) and 4th group (0.08). REE and Y, Zr, Ti indicate the metasomatic origin of garnets of 2, 3. 4 groups. Modeling of TREfor equilibrated melts and fractional crystallization 2nd group close to Turyino field basalts and 3-rd - to Izmozero field picrites of Arkhangelsk diamondiferous province (ADP). Basing on geochemical data of garnet xenocrysts and garnets and clinopyroxenes in peridotites (Shchukina et al., 2013, 2015) we suppose at least 3 stage of high-temperature metasomatic enrichment. 1st stage - is enrichment of residual garnets (found only in peridotite garnets) in LREE by the influence of carbonatite melt close to the Mela field carbonatites of ADP. REE patterns in clinopyroxenes from these peridotite samples and the geochemical modeling results show that clinopyroxenes are also in equilibrium with carbonatite melt. Formation of garnet with the sinusoidal REE pattern could also occurs during carbonatite stage of mantle metasomatism. The 2- nd stage - is formation of garnets of group 3 from the melt of composition close to Izhmozero field picrites. Garnets of group 3 are of lherzolite paragenesis on the content of CaO and Cr2O3, but their REE patterns are close to sinusoidal patterns. The final stage of mantle metasomatism is the formation of garnets of group 2 exposed to the melt of composition close to Turyino field basalts. Garnets of group 2 have low Cr2O3 that indicate the significant amounts of basaltic component in the resulting melt composition or direct crystallization from the melt in case of most low-chromium garnets and megacrysts garnets. Modeling results show that the formation of the garnets of group 2 in peridotites associated with crystallization of the clinopyroxenes. At this stage of mantle metasomatism garnets have typical major and trace element lherzolite composition.

Trace element transport in western Siberian rivers across a permafrost gradient

NASA Astrophysics Data System (ADS)

Pokrovsky, Oleg S.; Manasypov, Rinat M.; Loiko, Sergey V.; Krickov, Ivan A.; Kopysov, Sergey G.; Kolesnichenko, Larisa G.; Vorobyev, Sergey N.; Kirpotin, Sergey N.

2016-03-01

Towards a better understanding of trace element (TE) transport in permafrost-affected Earth surface environments, we sampled ˜ 60 large and small rivers (< 100 to ≤ 150 000 km2 watershed area) of the Western Siberian Lowland (WSL) during spring flood and summer and winter baseflow across a 1500 km latitudinal gradient covering continuous, discontinuous, sporadic and permafrost-free zones. Analysis of ˜ 40 major and TEs in the dissolved (< 0.45 µm) fraction allowed establishing main environmental factors controlling the transport of metals and TEs in rivers of this environmentally important region. No statistically significant effect of the basin size on most TE concentrations was evidenced. Two groups of elements were distinguished: (1) elements that show the same trend throughout the year and (2) elements that show seasonal differences. The first group included elements decreasing northward during all seasons (Sr, Mo, U, As, Sb) marking the underground water influence of river feeding. The elements of the second group exhibited variable behavior in the course of the year. A northward increase during spring period was mostly pronounced for Fe, Al, Co, Zn and Ba and may stem from a combination of enhanced leaching from the topsoil and vegetation and bottom waters of the lakes (spring overturn). A springtime northward decrease was observed for Ni, Cu, Zr and Rb. The increase in element concentration northward was observed for Ti, Ga, Zr and Th only in winter, whereas Fe, Al, rare earth elements (REEs), Pb, Zr, and Hf increased northward in both spring and winter, which could be linked to leaching from peat and transport in the form of Fe-rich colloids. A southward increase in summer was strongly visible for Fe, Ni, Ba, Rb and V, probably due to peat/moss release (Ni, Ba, Rb) or groundwater feeding (Fe, V). Finally, B, Li, Cr, V, Mn, Zn, Cd, and Cs did not show any distinct trend from S to N. The order of landscape component impact on TE concentration in rivers was lakes > bogs > forest. The lakes decreased export of Mn and Co in summer and Ni, Cu, and Rb in spring, presumably due to biotic processes. The lakes enriched the rivers in insoluble lithogenic elements in summer and winter, likely due to TE mobilization from unfrozen mineral sediments. The rank of environmental factors on TE concentration in western Siberian rivers was latitude (three permafrost zones) > season > watershed size. The effect of the latitude was minimal in spring for most TEs but highly visible for Sr, Mo, Sb and U. The main factors controlling the shift of river feeding from surface and subsurface flow to deep underground flow in the permafrost-bearing zone were the depth of the active (unfrozen) seasonal layer and its position in organic or mineral horizons of the soil profile. In the permafrost-free zone, the relative role of carbonate mineral-bearing base rock feeding versus bog water feeding determined the pattern of TE concentration and fluxes in rivers of various sizes as a function of season. Comparison of obtained TE fluxes in WSL rivers with those of other subarctic rivers demonstrated reasonable agreement for most TEs; the lithology of base rocks was the major factor controlling the magnitude of TE fluxes. Climate change in western Siberia and permafrost boundary migration will essentially affect the elements controlled by underground water feeding (DIC, alkaline earth elements (Ca, Sr), oxyanions (Mo, Sb, As) and U). The thickening of the active layer may increase the export of trivalent and tetravalent hydrolysates in the form of organo-ferric colloids. Plant litter-originated divalent metals present as organic complexes may be retained via adsorption on mineral horizon. However, due to various counterbalanced processes controlling element source and sinks in plant-peat-mineral soil-river systems, the overall impact of the permafrost thaw on TE export from the land to the ocean may be smaller than that foreseen with merely active layer thickening and permafrost boundary shift.

Halogen and trace element geochemistry in Mid-Ocean Ridge basalts from the Australian-Antarctic Ridge (AAR)

NASA Astrophysics Data System (ADS)

Yang, Y. S.; Seo, J. H.; Park, S. H.; Kim, T.

2015-12-01

Australian-Antarctic Ridge (AAR) is an extension of easternmost SE Indian Mid-Ocean Ridge (MOR).We collected volcanic glasses from the "in-axis" of the KR1 and KR2 MOR, and the overlapping zones of the KR1 MOR and the nearby seamounts ("KR1 mixing"). We determined trace and halogen elements in the glasses. Halogen concentrations and its ratios in the glasses are important to understand the mantle metasomatism and volatile recycling. 52 of the collected glasses are "primitive" (higher than 6 wt% MgO), while 3 of them have rather "evolved" composition (MgO wt% of 1.72, 2.95 and 4.15). K2O concentrations and Th/Sc ratios in the glasses show a negative correlation with its MgO concentration. Incompatible element ratios such as La/Sm are rather immobile during a magma differentiation so the ratios are important to understand mantle composition (Hofmann et al. 2003). La/Sm ratios in the glasses are 0.95 ~ 3.28 suggesting that the AAR basalts can be classified into T-MORB and E-MORB (Schilling et al., 1983). La/Sm ratios are well-correlated with incompatible elements such as U, Ba, Nb, and negatively correlated with compatible elements such as Sc, Eu2+, Mg. The AAR glasses contain detectable halogen elements. The "KR1 mixing" glasses in halogen elements are more abundant than "in-axis" the glasses. Cl is the least variable element compared to the other halogens such as Br and I in the AAR. The "KR1 mixing" glasses have the largest variations of Br/Cl ratios compared to the "in-axis" glasses. The Cl/Br and Th/Sc ratios in the "in-axis" glasses and in the "KR1 mixing" glasses show positive and negative correlations, respectively. The Br-rich glasses in the "KR1 mixing" zone might be explained by a recycled Br-rich oceanic slab of paleo-subduction or by a hydrothermal alteration in the AAR. I composition in the glasses does not show a correlation other trace elements. The K/Cl and K/Ti ratios in the AAR glasses are similar to the basalts from the Galapagos Spreading Center (Geldmacher et al., 2010) and Pacific MORB. The AAR region closely located with Balleny hotspot (Lanyon et al., 1993) and Pacific-Antarctic Ridge. K2O/Nb and Zr/Nb ratios are very low compared with near Pacific-Antarctic Ridge and Southeast Indian Ridge. The ratios are close to the Balleny hotspot.

Deformation Enhanced Recrystallization of Titanite: Insight from the Western Gneiss Region Ultrahigh-Pressure Terrane

NASA Astrophysics Data System (ADS)

Gordon, S. M.; Reddy, S. M.; Blatchford, H.; Whitney, D. L.; Kirkland, C. L.; Teyssier, C.; Evans, N. J.; McDonald, B.

2017-12-01

Titanite readily recrystallizes due to metamorphism, deformation, and/or fluids making it an ideal chronometer for tracking the exhumation of high-grade rocks. The Western Gneiss Region (WGR), Norway, is a giant UHP terrane exhumed as a fairly coherent slab. Parts of the WGR underwent little deformation during exhumation; however, meters-scale shear zones, located across the WGR, deformed over a range of pressures, from (U)HP to amphibolite facies. Titanite from quartzofeldpathic gneiss within, directly adjacent to, and 300 m away from a mylonitic shear zone within the southern WGR have been analyzed to track exhumation and investigate effects of deformation on recrystallization and trace-element mobility. EBSD was used to characterize the microstructural evolution of the gneisses, and trace-element concentrations and timing of recrystallization were estimated by split-stream LA-ICPMS. Titanite grain size decreases from outside (>200) to inside (<75 µm) the shear zone. Gneiss in and directly adjacent to the shear zone contain partially to completely recrystallized grains, with 207-corrected 206Pb/238U ages of <405 Ma. Gneiss within the shear zone shows a greater percentage of recrystallized grains. EBSD data indicate that some titanite comprises multiple subgrains within an optically coherent single grain. Subgrains in titanite cores show evidence of inherited radiogenic Pb, whereas subgrains in rims and tails of deformed sigma grains were recrystallized. In a gneiss directly adjacent to the shear zone, optically coherent grains are zoned, with increasing Sr and decreasing Zr from core to rim; titanite subgrains within the shear-zone gneiss are too small to analyze. In comparison, titanite from the gneiss outside the shear zone does not show any internal microstructures or evidence for Scandian recrystallization and has low U and high 204Pb. These results show that most trace elements are unaffected by deformation of titanite; however, Pb is mobile. Deformation thus plays an important role in resetting U-Pb systematics and allows the timing of shear zone development to be linked to the early stages of eclogite exhumation at ca. 405 Ma. Atom-probe analyses of adjacent subgrains, one that has recrystallized and one with an inherited age, will provide insight into trace-element mobility on the nm-scale.

Deformation Enhanced Recrystallization of Titanite: Insight from the Western Gneiss Region Ultrahigh-Pressure Terrane

NASA Astrophysics Data System (ADS)

Gordon, S. M.; Reddy, S. M.; Blatchford, H.; Whitney, D. L.; Kirkland, C. L.; Teyssier, C.; Evans, N. J.; McDonald, B.

2016-12-01

Titanite readily recrystallizes due to metamorphism, deformation, and/or fluids making it an ideal chronometer for tracking the exhumation of high-grade rocks. The Western Gneiss Region (WGR), Norway, is a giant UHP terrane exhumed as a fairly coherent slab. Parts of the WGR underwent little deformation during exhumation; however, meters-scale shear zones, located across the WGR, deformed over a range of pressures, from (U)HP to amphibolite facies. Titanite from quartzofeldpathic gneiss within, directly adjacent to, and 300 m away from a mylonitic shear zone within the southern WGR have been analyzed to track exhumation and investigate effects of deformation on recrystallization and trace-element mobility. EBSD was used to characterize the microstructural evolution of the gneisses, and trace-element concentrations and timing of recrystallization were estimated by split-stream LA-ICPMS. Titanite grain size decreases from outside (>200) to inside (<75 µm) the shear zone. Gneiss in and directly adjacent to the shear zone contain partially to completely recrystallized grains, with 207-corrected 206Pb/238U ages of <405 Ma. Gneiss within the shear zone shows a greater percentage of recrystallized grains. EBSD data indicate that some titanite comprises multiple subgrains within an optically coherent single grain. Subgrains in titanite cores show evidence of inherited radiogenic Pb, whereas subgrains in rims and tails of deformed sigma grains were recrystallized. In a gneiss directly adjacent to the shear zone, optically coherent grains are zoned, with increasing Sr and decreasing Zr from core to rim; titanite subgrains within the shear-zone gneiss are too small to analyze. In comparison, titanite from the gneiss outside the shear zone does not show any internal microstructures or evidence for Scandian recrystallization and has low U and high 204Pb. These results show that most trace elements are unaffected by deformation of titanite; however, Pb is mobile. Deformation thus plays an important role in resetting U-Pb systematics and allows the timing of shear zone development to be linked to the early stages of eclogite exhumation at ca. 405 Ma. Atom-probe analyses of adjacent subgrains, one that has recrystallized and one with an inherited age, will provide insight into trace-element mobility on the nm-scale.

Homogeneity of the geochemical reference material BRP-1 (paraná basin basalt) and assessment of minimum mass

USGS Publications Warehouse

Cotta, Aloisio J. B.; Enzweiler, Jacinta; Wilson, Stephen A.; Perez, Carlos A.; Nardy, Antonio J. R.; Larizzatti, Joao H.

2007-01-01

Reference materials (RM) are required for quantitative analyses and their successful use is associated with the degree of homogeneity, and the traceability and confidence limits of the values established by characterisation. During the production of a RM, the chemical characterisation can only commence after it has been demonstrated that the material has the required level of homogeneity. Here we describe the preparation of BRP-1, a proposed geochemical reference material, and the results of the tests to evaluate its degree of homogeneity between and within bottles. BRP-1 is the first of two geochemical RM being produced by Brazilian institutions in collaboration with the United States Geological Survey (USGS) and the International Association of Geoanalysts (IAG). Two test portions of twenty bottles of BRP-1 were analysed by wavelength dispersive-XRF spectrometry and major, minor and eighteen trace elements were determined. The results show that for most of the investigated elements, the units of BRP-1 were homogeneous at conditions approximately three times more rigorous than those strived for by the test of “sufficient homogeneity”. Furthermore, the within bottle homogeneity of BRP-1 was evaluated using small beam (1 mm2) synchrotron radiation XRF spectrometry and, for comparison, the USGS reference materials BCR-2 and GSP-2 were also evaluated. From our data, it has been possible to assign representative minimum masses for some major constituents (1 mg) and for some trace elements (1-13 mg), except Zr in GSP-2, for which test portions of 74 mg are recommended.

Multifunctional Beta Ti Alloy with Improved Specific Strength

NASA Astrophysics Data System (ADS)

Park, Chan Hee; Hong, Jae-Keun; Lee, Sang Won; Yeom, Jong-Taek

2017-12-01

Gum metals feature properties such as ultrahigh strength, ultralow elastic modulus, superelasticity, and superplasticity. They are composed of elements from Groups 4 and 5 of the periodic table and exist when the valance electron concentration (\\overline{e/a}) is 4.24; the bond order (\\overline{Bo}) is 2.87; and the "d" electron-orbital energy level (\\overline{Md}) is 2.45 eV. Typical compositions include Ti-23Nb-2Zr-0.7Ta-O and Ti-12Ta-9Nb-6Zr-3 V-O, which contain large amounts of heavy Group-5 elements such as Nb and Ta. In the present study, to improve the specific strength of a multifunctional beta Ti alloy, three alloys (Ti-20Nb-5Zr-1Fe-O, Ti-12Zr-10Mo-4Nb-O, and Ti-24Zr-9Cr-3Mo-O) were designed by satisfying the above three requirements while adding Fe, Mo, and Cr, which are not only lightweight but also have strong hardening effects. Microstructural and mechanical property analyses revealed that Ti-20Nb-5Zr-1Fe-O has a 25% higher specific strength than gum metal while maintaining an ultralow elastic modulus.

Alloying effect on the room temperature creep characteristics of a Ti-Zr-Be bulk metallic glass

NASA Astrophysics Data System (ADS)

Gong, Pan; Wang, Sibo; Li, Fangwei; Wang, Xinyun

2018-02-01

The effect of alloying elements (e.g. Fe, Al, and Ni) on the room temperature creep behavior of a lightweight Ti41Zr25Be34 bulk metallic glass (BMG) was investigated via nanoindentation tests. The generalized Kelvin model was adopted to describe the creep curves. The strain rate sensitivity m has been derived as a measure of the creep resistance. The compliance spectrum and retardation spectrum were also derived. The results show that the creep resistance of Ti41Zr25Be34 alloy can be obviously improved with the addition of alloying elements, and the most effective element is found to be Al. The mechanism for enhancing the creep resistance was discussed in terms of the scale variation of the shear transformation zone induced by alloying.

Iron aluminide useful as electrical resistance heating elements

DOEpatents

Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

1997-04-15

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {<=}1% Cr and either {>=}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {>=}0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, {<=}2% Ti, {<=}2% Mo, {<=}1% Zr, {<=}1% C, {<=}0.1% B, {<=}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1% rare earth metal, {<=}1% oxygen, {<=}3% Cu, balance Fe. 64 figs.

Holocene and late glacial palaeoceanography and palaeolimnology of the Black Sea: Changing sediment provenance and basin hydrography over the past 20,000 years

USGS Publications Warehouse

Piper, David Z.; Calvert, S.E.

2011-01-01

The elemental geochemistry of Late Pleistocene and Holocene sediments of the Black Sea, recovered in box cores from the basin margins and a 5-m gravity core from the central abyssal region of the basin, identifies two terrigenous sediment sources over the last 20 kyrs. One source region includes Anatolia and the southern Caucasus; the second region is the area drained by rivers entering the Black Sea from Eastern Europe. Alkali metal:Al and heavy:light rare-earth element ratios reveal that the relative contribution of the two sources shifted abruptly every few thousand years during the late glacial and early Holocene lacustrine phase of the basin. The shifts in source were coeval with changes in the lake level as determined from the distribution of quartz and the heavy mineral-hosted trace elements Ti and Zr.The geochemistry of the abyssal sediments further recorded a sequence of changes to the geochemistry of the water column following the lacustrine phase, when high salinity Mediterranean water entered the basin beginning 9.3 kyrs BP. Bottom water that had been oxic throughout the lake phase became anoxic at approximately 8.4 kyrs BP, as recorded by the accumulation from the water column of several redox-sensitive trace metals (Mo, Re, U). The accumulation of organic carbon and several trace nutrients (Cd, Cu, Ni, Zn) increased sharply ca. 0.4 kyrs later, at 8.0 kyrs BP, reflecting an increase of primary productivity. Its increase was coeval with a shift in the dinoflagellate ecology from stenohaline to euryhaline assemblages. During this profound environmental change from the lacustrine to the marine phase, the accumulation rate of the lithogenous sediment fraction decreased as much as 10-fold in response to the rise of the water level in the basin from a low stand ca. 9.3 ka to its current level.

Holocene and late glacial palaeoceanography and palaeolimnology of the Black Sea: Changing sediment provenance and basin hydrography over the past 20,000 years

USGS Publications Warehouse

Piper, D.Z.; Calvert, S.E.

2011-01-01

The elemental geochemistry of Late Pleistocene and Holocene sediments of the Black Sea, recovered in box cores from the basin margins and a 5-m gravity core from the central abyssal region of the basin, identifies two terrigenous sediment sources over the last 20. kyrs. One source region includes Anatolia and the southern Caucasus; the second region is the area drained by rivers entering the Black Sea from Eastern Europe. Alkali metal:Al and heavy:light rare-earth element ratios reveal that the relative contribution of the two sources shifted abruptly every few thousand years during the late glacial and early Holocene lacustrine phase of the basin. The shifts in source were coeval with changes in the lake level as determined from the distribution of quartz and the heavy mineral-hosted trace elements Ti and Zr. The geochemistry of the abyssal sediments further recorded a sequence of changes to the geochemistry of the water column following the lacustrine phase, when high salinity Mediterranean water entered the basin beginning 9.3. kyrs BP. Bottom water that had been oxic throughout the lake phase became anoxic at approximately 8.4. kyrs BP, as recorded by the accumulation from the water column of several redox-sensitive trace metals (Mo, Re, U). The accumulation of organic carbon and several trace nutrients (Cd, Cu, Ni, Zn) increased sharply ca. 0.4. kyrs later, at 8.0. kyrs BP, reflecting an increase of primary productivity. Its increase was coeval with a shift in the dinoflagellate ecology from stenohaline to euryhaline assemblages. During this profound environmental change from the lacustrine to the marine phase, the accumulation rate of the lithogenous sediment fraction decreased as much as 10-fold in response to the rise of the water level in the basin from a low stand ca. 9.3. ka to its current level.

The origin and evolution of silicic magmas during continental rifting: new constraints from trace elements and oxygen isotopes from Ethiopian volcanoes

NASA Astrophysics Data System (ADS)

Hutchison, W.; Boyce, A.; Mather, T. A.; Pyle, D. M.; Yirgu, G.; Gleeson, M. L.

2017-12-01

The petrologic diversity of rift magmas is generated by two key processes: interaction with the crust via partial melting or assimilation; and closed-system fractional crystallization of the parental magma. It is not yet known whether these two petrogenetic processes vary spatially between different rift settings, and whether there are any significant secular variations during rift evolution. The Ethiopian Rift is the ideal setting to test these hypotheses because it captures the transition from continental rifting to sea-floor spreading and has witnessed the eruption of large volumes of mafic and silicic volcanic rocks since 30 Ma. We use new oxygen isotope (δ18O) and trace element data to fingerprint fractional crystallisation and partial crustal melting processes in Ethiopia and evaluate spatial variations between three active rift segments. δ18O measurements are used to examine partial crustal melting processes. We find that most δ18O data from basalts to rhyolites fall within the bounds of modelled fractional crystallization trajectories (i.e., 5.5-6.5 ‰). Few samples deviate from this trend, emphasising that fractional crystallization is the dominant petrogenetic processes and that little fusible Precambrian crustal material (δ18O of 7-18 ‰) remain to be assimilated beneath the magmatic segments. Trace element systematics (e.g., Ba, Sr, Rb, Th and Zr) further underscore the dominant role of fractional crystallization but also reveal important variations in the degree of melt evolution between the volcanic systems. We find that the most evolved silicic magmas, i.e., those with greatest peralkalinity (molar Na2O+K2O>Al2O3), are promoted in regions of lowest magma flux off-axis and along rift. Our findings provide new information on the nature of the crust beneath Ethiopia's active magmatic segments and also have relevance for understanding ancient rift zones and the geotectonic settings that promote genesis of economically-valuable mineral deposits.

Peat Bog Archives: from human history, vegetation change and Holocene climate, to atmospheric dusts and trace elements of natural and anthropogenic origin

NASA Astrophysics Data System (ADS)

Shotyk, William

2010-05-01

For at least two centuries, peat has been recognized as an excellent archive of environmental change. William Rennie (1807), for example, interpreted stratigraphic changes in Scottish bogs not only in terms of natural changes in paleoclimate, but was also able to identify environmental changes induced by humans, namely deforestation and the hydrological impacts which result from such activities. The use of bogs as archives of climate change in the early 20th century was accelerated by studies of fossil plant remains such as those by Lewis in Scotland, and by systematic investigations of pollen grains pioneered by von Post in Sweden. In Denmark, Glob outlined the remarkably well-preserved remains of bog bodies and associated artefacts (of cloth, wood, ceramic and metal) in Danish bogs. In Britain, Godwin provided an introduction to the use of bogs as archives of human history, vegetation change, and Holocene climate, with a more recent survey provided by Charman. Recent decades have provided many mineralogical studies of peat and there is growing evidence that many silicate minerals, whether derived from the surrounding watershed or the atmosphere (soil-derived dusts and particles emitted from volcanoes), also are well preserved in anoxic peatland waters. Similarly, geochemical studies have shown that a long list of trace metals, of both natural and anthropogenic origin, also are remarkably well preserved in peat bogs. Thus, there is growing evidence that ombrotrophic (ie 'rain-fed') peat bogs are reliable archives of atmospheric deposition of a wide range of trace elements, including conservative, lithogenic metals such as Al, Sc, Ti, Y, Zr, Hf and the REE, but also the potentially toxic Class B, or 'heavy metals' such as Cu, Ag, Hg, Pb, Sb and Tl. When high quality measurements of these elements is combined with accurate radiometric age dating, it becomes possible to create high resolution reconstructions of atmospheric soil dust fluxes, ancient and modern metal pollution, and Holocene climate change.

Strawberry Rhyolites, Oregon: Northwestern extent of mid-Miocene flood basalt related rhyolites of the Pacific Northwest

NASA Astrophysics Data System (ADS)

Steiner, A. R.; Streck, M. J.

2011-12-01

Rhyolitic volcanism associated with the Columbia River-Steens flood basalts of the Pacific Northwest has traditionally been viewed to be centered at McDermitt caldera near the Oregon-Nevada border starting at ~16.5 Ma. In recent years, more rhyolitic centers along this latitude with ages between 16.5-15.5 Ma have been identified and associated with the inception of the Yellowstone hotspot. However the footprint of plume-head related rhyolites becomes much larger when silicic centers of mid-Miocene age in eastern Oregon are included extending the distribution of such rhyolites to areas near the towns of Baker City and John Day ~250 km north of McDermitt. This study addresses one of these rhyolitic centers that was virtually unknown and that constitutes the northwestern extent of mid-Miocene rhyolites. Rhyolites are centered ~40 km SSW of John Day and are considered part of the Strawberry Volcanic Field (SVF), which consists of a diverse group of volcanic rocks ranging from basalt to rhyolite with abundant intermediate compositions. One existing age date of 17.3 Ma ± 0.36 (Robyn, 1977) - if confirmed by our ongoing study - places these rhyolites at the very onset of plume-head related rhyolites. Strawberry rhyolitic lavas are most voluminous in the southwestern portion of the SVF covering approximately 500 km2 between Bear and Logan Valley. The rhyolitic lavas tend to be phenocryst-poor (<3%) and range from obsidian to devitrified flow banded rhyolites. The major phenocryst phases include plagioclase, quartz, and occasional biotite. Field evidence suggests that the aphyric high-silica rhyolite lavas (~77 wt. % SiO2) erupted first, followed by rhyolite lava flows with increasing phenocryst proportions and decreasing SiO2 (70 wt. %). Lastly, phenocryst-rich dacite lava erupted on top, capping the rhyolite. There is no evidence of significant time gaps between lavas flows, suggesting eruption in short succession. Rhyolites from the SVF are high-K, calc-alkaline lavas and are mostly metaluminous (e.g. 11.1 - 15.2 wt. % Al2O3, 0.06 - 2.70 wt. % CaO). Trace elements of Strawberry Rhyolites show minor variability except in, Sr (10 - 200 ppm), Zr (65 - 450 ppm), Ti (300 - 3500 ppm), and Ba (350 - 1600 ppm). When normalized to upper crustal values, Strawberry Rhyolites plot around 1 with significant troughs at Sr, P, Ti, and minor troughs in Ba, Nb, and Zr. REE patterns indicate slight LREE enrichment with LaN/YbN values ranging from 2.5 to 8.3 and higher values correlate positively with other differentiation indices (e.g. Ba, Sr, Eu/Eu*). Furthermore, major elements (e.g. SiO2 and FeO*) and trace elements (e.g. Ba, Sr, La, Zr/Hf) display common liquid lines of decent with Eu/Eu*. This suggests that the Strawberry Rhyolites are likely products of variable degrees of differentiation. Future petrogenetic evaluations will further investigate the origin of the Strawberry Rhyolites.

How does recycling of sediment components in arc magmatism really work?

NASA Astrophysics Data System (ADS)

Kelemen, P.; Hacker, B.; Austin, N.

2007-12-01

Past work indicates substantial recycling of a sediment component rich in LILE, Th, Sr, Pb and LREE in arcs. For example, in the relatively well-constrained case of Central America, Plank et al (Geology 02) estimate that 80% of subducted, sedimentary Th is recycled in arc magmas. To understand how such a component is transferred from subducted sediment to arc lava, we examined trace-element variation in (a) mid-crustal (0.4 GPa) contact metamorphic rocks (Austin & Kelemen, Fall 06 AGU) and (b) ultrahigh-pressure (UHP, > 3 GPa) metasediments. Most UHP samples were metamorphosed along subduction-zone geotherms (Hacker, Int Geol Rev 06), but some record substantially higher T (e.g., Erzgebirge & Kokchetav, Massone EPSL 03). Unmelted, mid-crustal metapelites are indistinguishable from pelitic sediments for the entire suite of elements analyzed by ICP-MS at WSU. Melt extraction from the mid-crustal metapelites led to systematic depletion of incompatible elements in high-grade hornfels. Depletion increases with decreasing distance to the contact with a mafic pluton, most clearly at peak T > 750°C. In contrast, although many UHP metapelites record PT above the aqueous fluid-saturated solidus, and have fluid inclusions and/or hydrous phases, compared to pelites they show no detectable depletion of "fluid-mobile" elements such as LILE (Cs, Rb, Ba, U, K), Sr and Pb, no depletion of "fluid-immobile, incompatible" elements such as Th and LREE, and no systematic change in key soluble/insoluble ratios such as Ba/Th or K/Zr up to ~1000 C. Mobility of incompatible elements is evident for T > 1000 C, well above PT for subduction-zone geotherms. Presumably, trace phases rich in LILE, Th and LREE persist to ~1050 C in metapelites at UHP conditions.How can our observations be reconciled with the recycled sediment component in arc lavas? Our preferred hypothesis is that low-density metasediments rise into the mantle wedge when heating yields viscosities low enough for density-driven instabilities (Ringwood JGSL 74; Marsh AJS 76; Gerya & Yuen EPSL 03; Kelemen et al, Treatise on Geochem 03). In the wedge, metasedimentary diapirs heat as they rise, and undergo large degrees of super-adiabatic partial melting which exhaust trace phases, releasing the sediment component observed in arcs.

Experimental partitioning of Zr, Ti, and Nb between silicate liquid and a complex noble metal alloy and the partitioning of Ti between perovskite and platinum metal

NASA Technical Reports Server (NTRS)

Jurewicz, Stephen R.; Jones, John H.

1993-01-01

El Goresy et al.'s observation of Nb, Zr, and Ta in refractory platinum metal nuggets (RPMN's) from Ca-Al-rich inclusions (CAI's) in the Allende meteorite led them to propose that these lithophile elements alloyed in the metallic state with noble metals in the early solar nebula. However, Grossman pointed out that the thermodynamic stability of Zr in the oxide phase is vastly greater than metallic Zr at estimated solar nebula conditions. Jones and Burnett suggested this discrepancy may be explained by the very non-ideal behavior of some lithophile transition elements in noble metal solutions and/or intermetallic compounds. Subsequently, Fegley and Kornacki used thermodynamic data taken from the literature to predict the stability of several of these intermetallic compounds at estimated solar nebula conditions. Palme and Schmitt and Treiman et al. conducted experiments to quantify the partitioning behavior of certain lithophile elements between silicate liquid and Pt-metal. Although their results were somewhat variable, they did suggest that Zr partition coefficients were too small to explain the observed 'percent' levels in some RPMN's. Palme and Schmitt also observed large partition coefficients for Nb and Ta. No intermetallic phases were identified. Following the work of Treiman et al., Jurewicz and Jones performed experiments to examine Zr, Nb, and Ti partitioning near solar nebula conditions. Their results showed that Zr, Nb, and Ti all have an affinity for the platinum metal, with Nb and Ti having a very strong preference for the metal. The intermetallic phases (Zr,Fe)Pt3, (Nb,Fe)Pt3, and (Ti,Fe)Pt3 were identified. Curiously, although both experiments and calculations indicate that Ti should partition strongly into Pt-metal (possibly as TiPt3), no Ti has ever been observed in any RPMN's. Fegley and Kornacki also noticed this discrepancy and hypothesized that the Ti was stabilized in perovskite which is a common phase in Allende CAI's.

Effect of Zr Inhibitor on Corrosion of Haynes 230 and NS-163 Alloys in Flinak

NASA Astrophysics Data System (ADS)

Peng, Yuxiang; Reddy, Ramana G.

The intrinsic corrosion behavior of Haynes 230 and NS-163 alloys after adding corrosion inhibitor Zr to LiF-NaF-KF (FLiNaK) salts was evaluated. Thermodynamic modeling studies were performed to investigate the compatibility of Haynes alloys for solar thermal energy storage applications in the molten salts. Equilibrium conditions were considered for predicting the corrosion products and weight loss of salts at higher temperatures (700 - 1000°C). Weight loss of FLiNaK salt after corrosion with or without inhibitor is less than 5%, indicating no significant change in compositions of FLiNaK even with Zr inhibitor. Furthermore, to compare with experimental data, modeling calculation with known amount of trace impurities (Ni2+, Fe3+ and so on) added to the molten salts, shows similar trend and corrosion product with and without Zr inhibitor.

Oxygen isotope and trace element evidence for three-stage petrogenesis of the youngest episode (260-79 ka) of Yellowstone rhyolitic volcanism

NASA Astrophysics Data System (ADS)

Loewen, Matthew W.; Bindeman, Ilya N.

2015-10-01

We report the first high-precision δ18O analyses of glass, δ18O of minerals, and trace element concentrations in glass and minerals for the 260-79 ka Central Plateau Member (CPM) rhyolites of Yellowstone, a >350 km3 cumulative volume of lavas erupted inside of 630 ka Lava Creek Tuff (LCT) caldera. The glass analyses of these crystal-poor rhyolites provide direct characterization of the melt and its evolution through time. The δ18Oglass values are low and mostly homogeneous (4.5 ± 0.14 ‰) within and in between lavas that erupted in four different temporal episodes during 200 ka of CPM volcanism with a slight shift to lower δ18O in the youngest episode (Pitchstone Plateau). These values are lower than Yellowstone basalts (5.7-6 ‰), LCT (5.5 ‰), pre-, and extracaldera rhyolites (~7-8 ‰), but higher than the earliest 550-450 ka post-LCT rhyolites (1-2 ‰). The glass δ18O value is coupled with new clinopyroxene analyses and previously reported zircon analyses to calculate oxygen isotope equilibration temperatures. Clinopyroxene records >900 °C near-liquidus temperatures, while zircon records temperatures <850 °C similar to zircon saturation temperature estimates. Trace element concentrations in the same glass analyzed for oxygen isotopes show evidence for temporal decreases in Ti, Sr, Ba, and Eu—related to Fe-Ti oxide and sanidine (±quartz) crystallization control, while other trace elements remain similar or are enriched through time. The slight temporal increase in glass Zr concentrations may reflect similar or higher temperature magmas (via zircon saturation) through time, while previosuly reported temperature decreases (e.g., Ti-in-quartz) might reflect changing Ti concentrations with progressive melt evolution. Multiple analyses of glass across single samples and in profiles across lava flow surfaces document trace element heterogeneity with compatible behavior of all analyzed elements except Rb, Nb, and U. These new data provide evidence for a three-stage geochemical evolution of these most recent Yellowstone rhyolites: (1) repeated batch melting events at the base of a homogenized low-δ18O intracaldera fill resulting in liquidus rhyolite melt and a refractory residue that sequesters feldspar-compatible elements over time. This melting may be triggered by conductive "hot plate" heating by basaltic magma intruding beneath the Yellowstone caldera resulting in contact rhyolitic melt that crystallizes early clinopyroxene and/or sanidine at high temperature. (2) Heterogeneity within individual samples and across flows reflects crystallization of these melts during preeruptive storage of magma at at lower, zircon-saturated temperatures. Compatible behavior and variations of most trace elements within individual lava flows are the result of sanidine, quartz, Fe-Ti oxide, zircon, and chevkinite crystallization at this stage. (3) Internal mixing immediately prior to and/or during eruption disrupts, these compositional gradients in each parental magma body that are preserved as melt domains distributed throughout the lava flows. These results based on the most recent and best-preserved volcanic products from the Yellowstone volcanic system provide new insight into the multiple stages required to generate highly fractionated hot spot and rift-related rhyolites. Our proposed model differs from previous interpretations that extreme Sr and Ba depletion result from long-term crystallization of a single magma body—instead we suggest that punctuated batch melting events generated a sanidine-rich refractory residue and a melt source region progressively depleted in Sr and Ba.

Laser ablation ICP-MS analysis on nano-powder pellets and applications to granite bulk rock analysis

NASA Astrophysics Data System (ADS)

Wu, Shitou; Karius, Volker; Wörner, Gerhard

2017-04-01

Granites are a ubiquitous component of the continental crust and knowing their precise trace element signatures is essential in understanding the origins and evolution of the continental crust. ICP-MS bulk analysis of granite is generally conducted on solution after acid-digestion. However this technique has several deficiencies related to the difficulty of completely dissolving accessary minerals such as zircon and the instability/adsorption of high valence trace elements (Nb, Ta et al.) in acid solutions. The development of a nano-powder pellet technique by using wet milling procedure, and its combination with laser ablation ICP-MS has been proposed to overcome these problems. In this study, we produced nano-powders from a series of granite rock standards by wet milling in agate using a high power planetary ball mill instrument. The procedure was tested and optimized by modifying parameters (ball to powder ratio, water to powder ratio, milling power etc.). Characterization of nano-powders was conducted by various techniques including electron microprobe (EMP), secondary electron imaging, polarizing microscope, and laser particle size analyzer (LPSA) and laser scanning confocal microscope (LSCM). Particle sizes range from a few nm to 5 μm with a small secondary mode at around 10 to 20 μm that probably represent particle aggregates rather than remaining crystal grains after milling. Pellets of 5 mm in diameter were pressed into molds of cellulose at 1.75 *103 N/cm2. Surface roughness of the pellets was measured by LSCM and gave a Ra of 0.494 μm, which is an order higher than the surface of polished ATGH-G reference glass surface (Ra: 0.048 μm), but sufficient for laser ablation. Sources of contamination either from abrading agate balls or from ultrapure water were evaluated and quantified. The homogeneity of powder pellets down to less than 5 μm size was documented based on EMPA element mapping and statistical analyses of LA-ICP-MS in discrete spot and line scanning analytical mode. We report data from major to trace element (to < 0.1 ppm) of currently available international granite reference materials (JG-2, JG-3, GWB07103, GEB07111, GSP-2 and G-3) to evaluate analytical precision and accuracy of LA-ICP-MS measurements. Our results illustrate the potential of this method for high precision analysis of trace elements and e.g. Zr/Hf and Nb/Ta ratios in granites.

Geochemistry of the Neoproterozoic metabasic rocks from the Negele area, southern Ethiopia: Tectonomagmatic implications

NASA Astrophysics Data System (ADS)

Yihunie, Tadesse; Adachi, Mamoru; Yamamoto, Koshi

2006-03-01

Neoproterozoic metabasic rocks along with metasediments and ultramafic rocks constitute the Kenticha and Bulbul lithotectonic domains in the Negele area. They occur as amphibolite and amphibole schist in the Kenticha, and amphibole schist and metabasalt in the Bulbul domains. These rocks are dominantly basaltic in composition and exhibit low-K tholeiitic characteristics. They are slightly enriched in large ion lithophile (LIL) and light rare earth (LRE) elements and depleted in high field strength (HFS) and heavy rare earth (HRE) elements. They exhibit chemical characteristics similar to back-arc basin and island-arc basalts, but include a few samples with slightly higher Y, Zr and Nb contents. Initial Sr isotopic ratios and ɛNd values for the Kenticha metabasic rocks range from 0.7048 to 0.7051 and from 4.7 to 9.6 whereas for the Bulbul metabasic rocks they range from 0.7032 to 0.7055 and from -0.1 to 5.5, respectively. The trace elements and Sr-Nd isotope compositions of samples from the Kenticha and Bulbul domains suggest similar, but isotopically heterogeneous magma sources. The magma is inferred to have derived from depleted source with a contribution from an enriched mantle source component.

Evaluation of neutron flux parameters in irradiation sites of research reactor using the Westcott-formalism for the k0 neutron activation analysis method

NASA Astrophysics Data System (ADS)

Kasban, H.; Hamid, Ashraf

2015-12-01

Instrumental Neutron Activation Analysis using k0 (k0-INAA) method has been used to determine a number of elements in sediment samples collected from El-Manzala Lake in Egypt. k0-INAA according to Westcott's formalism has been implemented using the complete irradiation kit of the fast pneumatic rabbit and some selected manually loaded irradiation sites for short and long irradiation at Egypt Second Research Reactor (ETRR-2). Zr-Au and Co sets as neutron flux monitors are used to determine the neutron flux parameters (f and α) in each irradiation sites. Two reference materials IAEA Soil-7 samples have been inserted and implemented for data validation and an internal monostandard multi monitor used (k0 based IM-NAA). It was given a good agreement between the experimental analyzed values and that obtained of the certified values. The major and trace elements in the sediment samples have been evaluated with the use of Co as an internal and Au as an external monostandard comparators. The concentrations of the elements (Cr, Mn and Zn) in the sediment samples of the present work are discussed regarding to those obtained from other sites.

Fuel element design for the enhanced destruction of plutonium in a nuclear reactor

DOEpatents

Crawford, Douglas C.; Porter, Douglas L.; Hayes, Steven L.; Hill, Robert N.

1999-01-01

A uranium-free fuel for a fast nuclear reactor comprising an alloy of Pu, Zr and Hf, wherein Hf is present in an amount less than about 10% by weight of the alloy. The fuel may be in the form of a Pu alloy surrounded by a Zr--Hf alloy or an alloy of Pu--Zr--Hf or a combination of both.

Tandem Laser Induced Breakdown Spectroscopy (LIBS), Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA-ICP-MS) and/or Laser Ablation Inductively Coupled Plasma Optical Emission Spectroscopy (LA-ICP-OES) for the analysis of samples of geological interest

NASA Astrophysics Data System (ADS)

Oropeza, D.

2016-12-01

A highly innovative laser ablation sampling instrument (J200 Tandem LA - LIBS) that combines the capabilities and analytical benefits of LIBS, LA-ICP-MS and LA-ICP-OES was used for micrometer-scale, spatially-resolved, elemental analysis of a wide variety of samples of geological interest. Data collected using ablation systems consisted of nanosecond (Nd:YAG operated 266nm) and femtosecond lasers (1030 and 343nm). An ICCD LIBS detector and Quadrupole based mass spectrometer were selected for LIBS and ICP-MS detection, respectively. This tandem instrument allows simultaneous determination of major and minor elements (for example, Si, Ca, Na, and Al, and trace elements such as Li, Ce, Cr, Sr, Y, Zn, Zr among others). The research also focused on elemental mapping and calibration strategies, specifically the use of emission and mass spectra for multivariate data analysis. Partial Least Square Regression (PLSR) is shown to minimize and compensate for matrix effects in the emission and mass spectra improving quantitative analysis by LIBS and LA-ICP-MS, respectively. The study provides a benchmark to evaluate analytical results for more complex geological sample matrices.

Effect of annealing temperature on the structural, morphological, and mechanical properties of polycrystalline zirconium oxynitride composite films deposited by plasma focus device

NASA Astrophysics Data System (ADS)

Khan, Ijaz A.; Kashif, Muhammad; Farid, Amjad; Rawat, Rajdeep S.; Ahmad, Riaz

2017-12-01

In this article, we reveal the post deposition annealing effect on the structural, morphological, and mechanical properties of polycrystalline zirconium oxynitride (P-ZrON) composite films deposited for 40 focus shots using a plasma focus device. The development of Zr(101), ZrN(111), ZrN(200), Zr3N4(320), ZrN0.28(002), and m-ZrO2(200) diffraction peaks confirms the deposition of P-ZrON composite films. The peak intensity, crystallite size, dislocation density, compressive stress, and texture coefficient of the Zr3N4(320) plane and the microstructural features such as the shape, size and distribution of nanoparticles as well as the film compactness are influenced by the annealing temperature. Elemental analysis confirms the presence of Zr, N, and O in the deposited films. The microhardness of the P-ZrON composite film annealed at 500 °C is found to be 11.87 GPa which is 7.8 times that of virgin zirconium.

Microstructure and Properties of DCP-Derived W-ZrC Composite Using Nontoxic Sodium Alginate to Fabricate WC Preform

NASA Astrophysics Data System (ADS)

Najafzadeh Khoee, Ali Asghar; Habibolahzadeh, Ali; Qods, Fathallah; Baharvandi, Hamidreza

2015-04-01

In the present work, tungsten carbide (WC) preforms were fabricated by gel-casting process, using different nontoxic Na-alginate to tertiary calcium phosphate ratios and different loadings of WC powder in the initial slurries. The gel-cast green bodies were dried and pre-sintered at 1723 K for 4 h and then reactively infiltrated by molten Zr2Cu at 1623 K for 0.5 h, to produce W-ZrC composite via displacive compensation of porosity process. The phases, microstructures, and mechanical properties of the preforms and the W-ZrC composites were investigated by Fourier transform infrared spectroscope, x-ray diffractometer (XRD), scanning electron microscope (SEM), image analyzer, and universal mechanical testing machine. XRD results, SEM micrographs, and elemental maps indicated uniform distribution of phases (W and ZrC) and elements (W, Zr, and C). Flexural strengths and hardness of the fabricated composites were in the ranges of 429-460 MPa and 7.5-9.5 GPa, respectively. Fractography studies revealed two types of dimple rupture and cleavage fracture modes in different composite samples. The W-ZrC composite was ablated by an oxyacetylene flame for 60 s. The mean value of mass and linear ablation rates of the composite were 2.1 ± 0.1 mg/s and 3.6 ± 0.5 µm/s, respectively.

Iron aluminide useful as electrical resistance heating elements

DOEpatents

Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

1997-01-01

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

Iron aluminide useful as electrical resistance heating elements

DOEpatents

Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

1999-01-01

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

Iron aluminide useful as electrical resistance heating elements

DOEpatents

Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

2001-01-01

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

Hydrous metasomatism of oceanic sub-arc mantle, Lihir, Papua New Guinea. Part 2. Trace element characteristics of slab-derived fluids

NASA Astrophysics Data System (ADS)

Grégoire, Michel; McInnes, Brent I. A.; O'Reilly, Suzanne Y.

2001-11-01

Spinel peridotite xenoliths recovered from the Tubaf and Edison volcanoes, south of Lihir Island in the Tabar-Lihir-Tanga-Feni island arc in Papua New Guinea, are predominantly fresh, refractory harzburgites. Many of the harzburgite xenoliths have cross-cutting vein networks and show evidence of modal metasomatism. These metasomatic veins contain a secondary mineral assemblage consisting of fibrous, radiating orthopyroxene and fine-grained Fe-Ni sulfide with minor olivine, clinopyroxene, phlogopite, amphibole and magnetite. Adjacent to the veins, primary clinopyroxene is cloudy while orthopyroxene exhibits replacement by secondary fibrous orthopyroxene, similar in habit to orthopyroxene occurring in the veins. The mineralogical and geochemical characteristics of the Tubaf mantle xenoliths are the product of two major processes: an early partial melting depletion event that was overprinted by oxidation and alkali enrichment related to percolation of slab-derived, hydrous melts. HREE and MREE concentrations in clinopyroxene from the least metasomatised harzburgites indicate that they are the residues from a 15% to 25% partial melting event, consistent with formation in a MOR setting. The secondary vein assemblages show strong enrichment in the LILE (primarily Sr, Ba, Rb, Th, U and Pb) and the REE (primarily La, Ce, Nd, Sm, Eu and Gd), while the HFSE (Nb, Ta, Zr, Hf, and Ti) are neither enriched nor depleted. The mineral precipitates in the vein assemblages have high LREE/HFSE and LILE/HFSE, and reflect the relative solubility of these elements in hydrous melts. These trace element characteristics are similar to those of the Tabar-Lihir-Tanga-Feni arc lavas, and display the commonly observed HFSE depletion of arc magmatism. These findings support the hypothesis that this so-called "arc signature" is primarily dependent on the relative solubility of elements in slab-derived, hydrous melts, and the enrichment of these soluble elements in metasomatised mantle regions that are prone to preferential partial melting.

Trace impurities analysis determined by neutron activation in the PbI 2 crystal semiconductor

NASA Astrophysics Data System (ADS)

Hamada, M. M.; Oliveira, I. B.; Armelin, M. J.; Mesquita, C. H.

2003-06-01

In this work, a methodology for impurity analysis of PbI 2 was studied to investigate the effectiveness of the purification. Commercial salts were purified by the multi passes zone refining and grown by the Bridgman method. To evaluate the purification efficiency, samples from the bottom, middle and upper sections of the ZR ingot were analyzed after 200, 300 and 500 purification passes, by measurements of the impurity concentrations, using the neutron activation analysis (NAA) technique. There was a significant reduction of the impurities according to the purification numbers. The reduction efficiency was different for each element, namely: Au>Mn>Co˜Ag>K˜Br. The impurity concentration of the crystals grown after 200, 300 and 500 passes and the PbI 2 starting material were analyzed by NAA and plasma optical emission spectroscopy.

Geochemical zoning and early differentiation in the moon

NASA Technical Reports Server (NTRS)

Taylor, S. R.; Jakes, P.

1977-01-01

The volatile elements (e.g., Rb, Pb, Tl, Bi, Cs) seem to have been depleted at the time of lunar accretion. Accordingly, it may be assumed that the moon initially accreted from refractory material. The good correlation between volatile/involatile element ratios (e.g., Cs/U, K/La, K/Zr) in both highland and maria samples means that element distribution in lunar crustal rocks is not governed by volatility differences. This and other evidence encourages the view that the moon was accreted homogeneously. A consequence of homogeneous accretion theories is that very efficient large-scale element fractionation is required to account both for the high near-surface concentrations of refractory elements (e.g., Th, U, REE, Zr, Ba, etc.) and for the Ca-Al-rich crust.

FCRD Advanced Reactor (Transmutation) Fuels Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janney, Dawn Elizabeth; Papesch, Cynthia Ann

2016-09-01

Transmutation of minor actinides such as Np, Am, and Cm in spent nuclear fuel is of international interest because of its potential for reducing the long-term health and safety hazards caused by the radioactivity of the spent fuel. One important approach to transmutation (currently being pursued by the DOE Fuel Cycle Research & Development Advanced Fuels Campaign) involves incorporating the minor actinides into U-Pu-Zr alloys, which can be used as fuel in fast reactors. U-Pu-Zr alloys are well suited for electrolytic refining, which leads to incorporation rare-earth fission products such as La, Ce, Pr, and Nd. It is, therefore, importantmore » to understand not only the properties of U-Pu-Zr alloys but also those of U-Pu-Zr alloys with concentrations of minor actinides (Np, Am) and rare-earth elements (La, Ce, Pr, and Nd) similar to those in reprocessed fuel. In addition to requiring extensive safety precautions, alloys containing U, Pu, and minor actinides (Np and Am) are difficult to study for numerous reasons, including their complex phase transformations, characteristically sluggish phasetransformation kinetics, tendency to produce experimental results that vary depending on the histories of individual samples, rapid oxidation, and sensitivity to contaminants such as oxygen in concentrations below a hundred parts per million. Although less toxic, rare-earth elements such as La, Ce, Pr, and Nd are also difficult to study for similar reasons. Many of the experimental measurements were made before 1980, and the level of documentation for experimental methods and results varies widely. It is, therefore, not surprising that little is known with certainty about U-Pu-Zr alloys, particularly those that also contain minor actinides and rare-earth elements. General acceptance of results commonly indicates that there is only a single measurement for a particular property. This handbook summarizes currently available information about U, Pu, Zr, Np, Am, La, Ce, Pr, and Nd and alloys of two or three of these elements. It contains information about phase diagrams and related information (including phases and phase transformations); heat capacity, entropy, and enthalpy; thermal expansion; and thermal conductivity and diffusivity. In addition to presenting information about materials properties, the handbook attempts to provide information about how well the property is known and how much variation exists between measurements. Although it includes some results from models, its primary focus is experimental data. The Handbook is organized in two sections: one with information about the U-Pu-Zr ternary and one with information about other elements and binary and vi ternary alloys in the U-Np-Pu-Am-La-Ce-Pr-Nd-Zr system. Within each section, information about elements is presented first, followed by information about binary alloys, then information about ternary alloys. The order in which the elements in each alloy are mentioned follows the order in the first sentence of this paragraph. Much of the information on the U-Pu-Zr system repeats information from the FCRD Transmutation Fuels Handbook 2015. Most of the other data has been published elsewhere (although scattered throughout numerous references, some quite obscure); however, some data from Idaho National Laboratory is presented here for the first time. As the FCRD programmatic mission evolves, future editions of this handbook will begin to include other advanced reactor fuel designs and compositions. Hence, the title of the handbook will transition to the Advanced Reactor Fuels Handbook.« less

Microstructural Evolution of the Interface Between Pure Titanium and Low Melting Point Zr-Ti-Ni(Cu) Filler Metals

NASA Astrophysics Data System (ADS)

Lee, Dongmyoung; Sun, Juhyun; Kang, Donghan; Shin, Seungyoung; Hong, Juhwa

2014-12-01

Low melting point Zr-based filler metals with melting point depressants (MPDs) such as Cu and Ni elements are used for titanium brazing. However, the phase transition of the filler metals in the titanium joint needs to be explained, since the main element of Zr in the filler metals differs from that of the parent titanium alloys. In addition, since the MPDs easily form brittle intermetallics, that deteriorate joint properties, the phase evolution they cause needs to be studied. Zr-based filler metals having Cu content from 0 to 12 at. pct and Ni content from 12 to 24 at. pct with a melting temperature range of 1062 K to 1082 K (789 °C to 809 °C) were wetting-tested on a titanium plate to investigate the phase transformation and evolution at the interface between the titanium plate and the filler metals. In the interface, the alloys system with Zr, Zr2Ni, and (Ti,Zr)2Ni phases was easily changed to a Ti-based alloy system with Ti, Ti2Ni, and (Ti,Zr)2Ni phases, by the local melting of parent titanium. The dissolution depths of the parent metal were increased with increasing Ni content in the filler metals because Ni has a faster diffusion rate than Cu. Instead, slow diffusion of Cu into titanium substrate leads to the accumulation of Cu at the molten zone of the interface, which could form undesirable Ti x Cu y intermetallics. This study confirmed that Zr-based filler metals are compatible with the parent titanium metal with the minimum content of MPDs.

Ultramafic xenoliths from the Bearpaw Mountains, Montana, USA: Evidence for multiple metasomatic events in the lithospheric mantle beneath the Wyoming craton

USGS Publications Warehouse

Downes, H.; Macdonald, R.; Upton, B.G.J.; Cox, K.G.; Bodinier, J.-L.; Mason, P.R.D.; James, D.; Hill, P.G.; Hearn, B.C.

2004-01-01

Ultramafic xenoliths in Eocene minettes of the Bearpaw Mountains volcanic field (Montana, USA), derived from the lower lithosphere of the Wyoming craton, can be divided based on textural criteria into tectonite and cumulate groups. The tectonites consist of strongly depleted spinel lherzolites, harzbugites and dunites. Although their mineralogical compositions are generally similar to those of spinel peridotites in off-craton settings, some contain pyroxenes and spinels that have unusually low Al2O3 contents more akin to those found in cratonic spinel peridotites. Furthermore, the tectonite peridotites have whole-rock major element compositions that tend to be significantly more depleted than non-cratonic mantle spinel peridotites (high MgO, low CaO, Al2O3 and TiO2) and resemble those of cratonic mantle. These compositions could have been generated by up to 30% partial melting of an undepleted mantle source. Petrographic evidence suggests that the mantle beneath the Wyoming craton was re-enriched in three ways: (1) by silicate melts that formed mica websterite and clinopyroxenite veins; (2) by growth of phlogopite from K-rich hydrous fluids; (3) by interaction with aqueous fluids to form orthopyroxene porphyroblasts and orthopyroxenite veins. In contrast to their depleted major element compositions, the tectonite peridotites are mostly light rare earth element (LREE)-enriched and show enrichment in fluid-mobile elements such as Cs, Rb, U and Pb on mantle-normalized diagrams. Lack of enrichment in high field strength elements (HFSE; e.g. Nb, Ta, Zr and Hf) suggests that the tectonite peridotites have been metasomatized by a subduction-related fluid. Clinopyroxenes from the tectonite peridotites have distinct U-shaped REE patterns with strong LREE enrichment. They have 143Nd/144Nd values that range from 0??5121 (close to the host minette values) to 0??5107, similar to those of xenoliths from the nearby Highwood Mountains. Foliated mica websterites also have low 143Nd/144Nd values (0??5113) and extremely high 87Sr/86Sr ratios in their constituent phlogopite, indicating an ancient (probably mid-Proterozoic) enrichment. This enriched mantle lithosphere later contributed to the formation of the high-K Eocene host magmas. The cumulate group ranges from clinopyroxene-rich mica peridotites (including abundant mica wehrlites) to mica clinopyroxenites. Most contain >30% phlogopite. Their mineral compositions are similar to those of phenocrysts in the host minettes. Their whole-rock compositions are generally poorer in MgO but richer in incompatible trace elements than those of the tectonite peridotites. Whole-rock trace element patterns are enriched in large ion lithophile elements (LILE; Rb, Cs, U and Pb) and depleted in HFSE (Nb, Ta Zr and Hf as in the host minettes, and their Sr-Nd isotopic compositions are also identical to those of the minettes. Their clinopyroxenes are LREE-enriched and formed in equilibrium with a LREE-enriched melt closely resembling the minettes. The cumulates therefore represent a much younger magmatic event, related to crystallization at mantle depths of minette magmas in Eocene times, that caused further metasomatic enrichment of the lithosphere. ?? Oxford University Press 2004; all rights reserved.

Fuel element design for the enhanced destruction of plutonium in a nuclear reactor

DOEpatents

Crawford, D.C.; Porter, D.L.; Hayes, S.L.; Hill, R.N.

1999-03-23

A uranium-free fuel for a fast nuclear reactor comprising an alloy of Pu, Zr and Hf, wherein Hf is present in an amount less than about 10% by weight of the alloy. The fuel may be in the form of a Pu alloy surrounded by a Zr--Hf alloy or an alloy of Pu--Zr--Hf or a combination of both. 7 figs.

Trace Metal-Humic Complexes in Natural Waters: Insights From Speciation Experiments

NASA Astrophysics Data System (ADS)

Stern, J. C.; Salters, V.; Sonke, J.

2006-12-01

The DOM cycle is intimately linked to the cycling and bioavailability of trace metals in aqueous environments. The presence or absence of DOM in the water column can determined whether trace elements will be present in limited quantities as a nutrient, or in surplus quantities as a toxicant. Humic substances (HS), which represent the refractory products of DOM degradation, strongly affect the speciation of trace metals in natural waters. To simulate metal-HS interactions in nature, experiments must be carried out using trace metal concentrations. Sensitive detection systems such as ICP-MS make working with small (nanomolar) concentrations possible. Capillary electrophoresis coupled with ICP-MS (CE-ICP-MS) has recently been identified as a rapid and accurate method to separate metal species and calculate conditional binding constants (log K_c) of metal-humic complexes. CE-ICP-MS was used to measure partitioning of metals between humic substances and a competing ligand (EDTA) and calculate binding constants of rare earth element (REE) and Th, Hf, and Zr-humic complexes at pH 3.5-8 and ionic strength of 0.1. Equilibrium dialysis ligand exchange (EDLE) experiments to validate the CE-ICP-MS method were performed to separate the metal-HS and metal-EDTA species by partitioning due to size exclusion via diffusion through a 1000 Da membrane. CE-ICP-MS experiments were also conducted to compare binding constants of REE with humic substances of various origin, including soil, peat, and aquatic DOM. Results of our experiments show an increase in log K_c with decrease in ionic radius for REE-humic complexes (the lanthanide contraction effect). Conditional binding constants of tetravalent metal-humic complexes were found to be several orders of magnitude higher than REE-humic complexes, indicating that tetravalent metals have a very strong affinity for humic substances. Because thorium is often used as a proxy for the tetravalent actinides, Th-HS binding constants can allow us to assess the importance of tetravalent actinide-humic complexes in groundwater transport from nuclear repositories. Our results suggest that tetravalent actinide-humic complexes couild be more important to account for in predictive speciation models than previously thought.

New limits for the 2 νββ decay of 96Zr to excited nuclear states of 96Mo

NASA Astrophysics Data System (ADS)

Finch, Sean; Tornow, Werner

2015-10-01

The final results from our search for the 2 νββ decay of 96Zr to excited 0+ and 2+ states of 96Mo are presented. Such measurements provide valuable test cases for 2 νββ -decay nuclear matrix element calculations, which in turn are used to tune 0 νββ -decay nuclear matrix element calculations. After undergoing double- β decay to an excited state, the excited daughter nucleus decays to the ground state, emitting two coincident γ rays. These two γ rays are detected in coincidence by two HPGe detectors sandwiching the 96Zr sample, with a NaI veto in anti-coincidence. This experimental apparatus, located at the Kimballton Underground Research Facility (KURF), has previously measured the 2 νββ decay of 100Mo and 150Nd to excited nuclear states. Experimental limits on the T1 / 2 and corresponding nuclear matrix element are presented for each of these decays. As a byproduct of this experiment, limits were also set on the single- β decay of 96Zr. Supported by DOE Grant: DE-FG02-97ER41033.

The effect of lanthanum on the fabrication of ZrB{sub 2}-ZrC composites by spark plasma sintering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Kyoung Hun; Shim, Kwang Bo

2003-01-15

The effect of the addition of the rare earth element, lanthanum, on the sintering characteristics of ZrB{sub 2}-ZrC composites has been analyzed during a spark plasma sintering (SPS) process. Microscopic observation confirmed that lanthanum accelerated mass transport by the formation of the liquid phase between the particles induced by the spark plasma in the initial stage of the SPS process, and then these were recrystallized to form a lanthanum-containing secondary phase at the grain boundaries and at the grain boundary triple junctions. In spite of the strong covalent bonding characteristics of the ZrB{sub 2}-ZrC composite there are many well-developed dislocationmore » structures observed. The fracture toughness of the lanthanum-containing ZrB{sub 2}-ZrC is about 2.56 MPa m{sup 1/2}, which is comparable to that of the pure composite. Therefore, it is concluded that lanthanum is very effective as a sintering aid for the ZrB{sub 2}-ZrC composite without any degradation of the mechanical properties.« less

Microstructure and mechanical behavior of Zr substrates coated with FeCrAl and Mo by cold-spraying

NASA Astrophysics Data System (ADS)

Park, Dong Jun; Kim, Hyun Gil; Jung, Yang Il; Park, Jung Hwan; Yang, Jae Ho; Koo, Yang Hyun

2018-06-01

FeCrAl and Mo layers were cold-sprayed onto a Zr surface, with the Mo layer introduced between the FeCrAl coating and the Zr matrix preventing high-temperature interdiffusion. Microstructural characterization of the first-deposited Mo layer and the Zr matrix immediately below the Mo/Zr interface was performed using transmission electron microscopy, and near-interface elemental distributions were obtained using energy-dispersive X-ray spectroscopy. The deformation of the coated Mo powder induced the formation of microbands and mechanically interlocked nanoscale structures. The mechanical behavior of Zr with a coating layer was compared with those characteristic of conventional Zr samples. The coated sample showed smaller strength reduction in the test conducted at elevated temperature. The hardness and fracture morphology of the Zr matrix near the interface region were investigated to determine the effect of impacting Mo particles on the matrix microstructure. The enhanced hardness and cleavage fracture morphology of the Zr matrix immediately below the Mo/Zr interface indicated the occurrence of localized deformation owing to Mo particle impact.

Origin and spatial distribution of metals in moss samples in Albania: A hotspot of heavy metal contamination in Europe.

PubMed

Lazo, Pranvera; Steinnes, Eiliv; Qarri, Flora; Allajbeu, Shaniko; Kane, Sonila; Stafilov, Trajce; Frontasyeva, Marina V; Harmens, Harry

2018-01-01

This study presents the spatial distribution of 37 elements in 48 moss samples collected over the whole territory of Albania and provides information on sources and factors controlling the concentrations of elements in the moss. High variations of trace metals indicate that the concentrations of elements are affected by different factors. Relations between the elements in moss, geochemical interpretation of the data, and secondary effects such as redox conditions generated from local soil and/or long distance atmospheric transport of the pollutants are discussed. Zr normalized data, and the ratios of different elements are calculated to assess the origin of elements present in the current moss samples with respect to different geogenic and anthropogenic inputs. Factor analysis (FA) is used to identify the most probable sources of the elements. Four dominant factors are identified, i.e. natural contamination; dust emission from local mining operations; atmospheric transport of contaminants from local and long distance sources; and contributions from air borne marine salts. Mineral particle dust from local emission sources is classified as the most important factor affecting the atmospheric deposition of elements accumulated in the current moss samples. The open slag dumps of mining operation in Albania is probably the main factor contributing to high contents of Cr, Ni, Fe, Ti and Al in the moss. Enrichment factors (EF) were calculated to clarify whether the elements in the present moss samples mainly originate from atmospheric deposition and/or local substrate materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inorganic trace element content of aerosols at puy de Dôme, France

NASA Astrophysics Data System (ADS)

Vlastelic, I.; Sellegri, K.; Colomb, A.; Suchroski, K.; Bouvier, L.; Nauret, F.

2012-04-01

The puy de Dôme research station is located at 1465 m above sea level in central France (45° 46' N, 2° 57' E, 1465 m a.s.l.). The station is surrounded by a protected area where agriculture and forests are predominant. The city of Clermont-Ferrand (150 000 inhabitants) is located 16 km east of the station. At the pdD site, the dominant westerly winds bring background or aged air masses. Despite its relatively low elevation, long-term records of gases and meteorological parameters indicate that in winter the site is mainly located in the free troposphere. Aerosol physical and chemical properties (particle size, black carbon mass), and gas-phase mixing ratios (SO2, CO, CO2, O3, NO, and NO2) are measured continuously throughout the year. Since October 2011, inorganic trace element content of aerosols is also monitored weekly. Precisely measured air volumes (typically from 15 to 20 m3) are filtered during two consecutive days and two consecutive nights on high purity teflon filters (47 mm diameter and 1.0 micrometer porosity). The Teflon filters are leached in savillex beakers using HNO3(0.4M) - HF (0.05M) and trace elements concentrations are analyzed by ICPMS (Agilent 7500, Laboratoire Magmas et Volcans). Preliminary data were analyzed in logarithmic plots sorting elements according to their decreasing abundance in the upper continental crust. A first group of elements (Al, Na, Fe, Mg, Ti, Mn, Ba, Sr, Zr, V, Cr, Rb, Li, Y, Ga, Co, Sc, Nb, Th, Hf, Cs, U, Be, Ta and Rare Earth Elements) shows a progressive decreasing trend, which suggests a crustal origin. A second group of elements (Zn, Ni, Cu, B, Pb, As, Sn, W, Ge, Mo, Tl, Sb, Bi, Se, Cd, In and Ag) shows strong positive anomalies that superimpose on the smooth trend. With the exception of Ni, all elements from this second group are volatile to some degree. The excess element concentration (i.e., unsupported by crustal input) decreases in the following order: Zn (7.75 ng/m3), B (1.2 ng/m3), Ni (0.44 ng/m3), Pb (0.34 ng/m3), Sn and Ag (0.18 ng/m3), W (0.13 ng/m3), Sb, As, Mo, Bi, Se, Cd, Ge (<0.1 ng/m3). Over the limited time-period yet investigated, the large variations of concentration ratios, such as Al/Ti (5 to 338) and Zn/Pb (0.5 to 196), point to important and rapid changes in element sources. These changes are currently examined in the light of air mass back-trajectories.

Structural, microstructural and thermal analysis of U-(6-x)Zr-xNb alloys (x = 0, 2, 4, 6)

NASA Astrophysics Data System (ADS)

Kaity, Santu; Banerjee, Joydipta; Parida, S. C.; Bhasin, Vivek

2018-06-01

Uranium-rich U-Zr-Nb alloy is considered as a good alternative fuel for fast reactors from the perspective of excellent dimensional stability and desired thermo-physical properties to achieve higher burnup. Detailed investigations related to the structural and microstructural characterization, thermal expansion, phase transformation, microhardness were carried out on U-6Zr, U-4Zr-2Nb, U-2Zr-4Nb and U-6Nb alloys (composition in wt%) where the total amount of alloying elements was restricted to 6 wt%. Structural, microstructural and thermal analysis studies revealed that these alloys undergo a series of transformations from high temperature bcc γ-phase to a variety of equilibrium and intermediate phases depending upon alloy composition, cooling rate and quenching. The structural analysis was carried out by Rietveld refinement. The data of U-Nb and U-Zr-Nb alloys have been highlighted and compared with binary U-Zr alloy.

COATED CARBON ELEMENT FOR USE IN NUCLEAR REACTORS AND THE PROCESS OF MAKING THE ELEMENT

DOEpatents

Pyle, R.J.; Allen, G.L.

1963-01-15

S>This patent relates to a carbide-nitride-carbide coating for carbon bodies that are to be subjected to a high temperature nuclear reactor atmosphere, and a method of applying the same. This coating is a highly efficient diffusion barrier and protects the C body from corrosion and erosion by the reactor atmosphere. Preferably, the innermost coating is Zr carbide, the middle coatlng is Zr nitride, and the outermost coating is a mixture of Zr and Nb carbide. The nitride coating acts as a diffusion barrier, while the innermost carbide bonds the nitride to the C body and prevents deleterious reaction between the nitride and C body. The outermost carbide coating protects the nitride coating from the reactor atmosphere. (AEC)

Chemical separation of Mo and W from terrestrial and extraterrestrial samples via anion exchange chromatography.

PubMed

Nagai, Yuichiro; Yokoyama, Tetsuya

2014-05-20

A new two-stage chemical separation method was established using an anion exchange resin, Eichrom 1 × 8, to separate Mo and W from four natural rock samples. First, the distribution coefficients of nine elements (Ti, Fe, Zn, Zr, Nb, Mo, Hf, Ta, and W) under various chemical conditions were determined using HCl, HNO3, and HF. On the basis of the obtained distribution coefficients, a new technique for the two-stage chemical separation of Mo and W, along with the group separation of Ti-Zr-Hf, was developed as follows: 0.4 M HCl-0.5 M HF (major elements), 9 M HCl-0.05 M HF (Ti-Zr-Hf), 9 M HCl-1 M HF (W), and 6 M HNO3-3 M HF (Mo). After the chemical procedure, Nb remaining in the W fraction was separated using 9 M HCl-3 M HF. On the other hand, Nb and Zn remaining in the Mo fraction were removed using 2 M HF and 6 M HCl-0.1 M HF. The performance of this technique was evaluated by separating these elements from two terrestrial and two extraterrestrial samples. The recovery yields for Mo, W, Zr, and Hf were nearly 100% for all of the examined samples. The total contents of the Zr, Hf, W, and Mo in the blanks used for the chemical separation procedure were 582, 9, 29, and 396 pg, respectively. Therefore, our new separation technique can be widely used in various fields of geochemistry, cosmochemistry, and environmental sciences and particularly for multi-isotope analysis of these elements from a single sample with significant internal isotope heterogeneities.

Determining Sediment Sources in the Anacostia River Watershed

NASA Astrophysics Data System (ADS)

Devereux, O. H.; Needelman, B. A.; Prestegaard, K. L.; Gellis, A. C.; Ritchie, J. C.

2005-12-01

Suspended sediment is a water-quality problem in the Chesapeake Bay. This project is designed to identify sediment sources in an urban watershed, the Northeast Branch of the Anacostia River (in Washington, D.C. and Maryland - drainage area = 188.5 km2), which delivers sediment directly to the Bay. This watershed spans two physiographic regions - the Piedmont and Coastal Plain. Bank sediment and suspended-sediment deposits were characterized using the following techniques: radionuclide (Cs-137) analysis by gamma ray spectrometry, trace-element analysis by ICP-MS, clay mineralogy by XRD, and particle-size analysis by use of a laser particle-size analyzer. Sampling of bank and suspended sediment was designed to: a) characterize tributary inputs from both Piedmont and Coastal Plain sources, and b) differentiate tributary inputs from bank erosion along the main stem of the Northeast Branch. Thirteen sample sites were chosen that represent tributary source areas of each physiographic region and the main stem where mixing occurs. Surface samples of the banks were compared to overbank deposits from a ten year storm (a proxy for the suspended sediments). Fingerprint components are selected from these data. Cesium-137 concentrations were analyzed for bank and overbank deposits for each physiographic region. No clear differences were seen between the two physiographic regions. Significant differences were observed between upland tributaries and the main stem of the Anacostia River. The average activity of Cs-137 for the tributaries was 5.4 bq/kg and the average for the main stem was 1.1 bq/kg. This suggests that there is significant erosion and storage of sediment in the tributaries. The low activity from Cs-137 in the main stem suggests a lack of storage of sediment along the main stem of the river. For the trace-element data, we focused on elements that showed significant variation among the sites. For the bank sediment, these elements include: Sr, V, Y, Ce, and Nd. For the overbank deposits, Zr, V, Ba, Ce, and Cu showed significant variability. In both physiographic regions, Pb is primarily found in bank deposits, while Cu is found in higher concentrations in overbank deposits. The Cs-137 data clearly showed the erosion and storage of sediment patterns in the watershed. The trace-element data indicate that stream banks may be differentiated from overbank deposits.

Major to ultra trace elements in rainfall collected in suburban Tokyo

NASA Astrophysics Data System (ADS)

Shimamura, Tadashi; Iwashita, Masato; Iijima, Satoe; Shintani, Megumi; Takaku, Yuichi

Major to ultra trace elements such as rare earth elements (REEs), platinum group elements (PGEs) in 20 rainfall events from suburban Tokyo were determined by inductively coupled plasma mass spectrometry (ICP-MS). Anion species were also determined by an ion chromatography (IC). The concentrations of PGEs were so low that only Pt was detected in some rainfall events. Enrichment factors (EFs), refer to soil and sea salt components, were calculated for the measured elements (with Al and Na as references). Be, (Na), Mg, (Al), Si, Cl, K, Fe, Rb, Sr, REEs (except La, Gd), Ta, and U were mostly originated from natural materials (soil and sea salt). For Li, B, Ca, Mn, Sr, Ba, and Cs, the contribution of natural materials was significant. EFs for Cu, Zn, As, Se, Sb, Cd, Pb, Bi, Ag, Te, Au, Pt, SO 4-S and NO 3-N exceeded 100 indicating non-crustal, non-sea salt origin, presumably anthropogenic; however, contribution of volcanic gases could not be excluded for As, Se, Te and Bi. Pt seemed to be uniformly distributed worldwide and a catalyst for automobile emission control may be the main source. Au also showed uniform distribution. On the other hand, EFs for Zr, Nb, Hf and Th were less than unity. Probably these elements resided in acid resistant refractory fine minerals that did not decompose with acid treatment, and did not evaporate and ionize in the ICP. An alternative explanation is that the concentration of these elements was lower in the soil of the sampling area than the average crust. In the crust normalized REE pattern plot, La, Eu and Gd showed clear positive anomalies. La and Gd could have anthropogenic components. A possible source of La and Gd is cracking catalyst for petrol refining, but this source does not fully explain the anomaly. The source of Gd may also be Gd-DTPA (Gadolinium (III) diethyltriaminepentaacetic acid) used for Magnetic Resonance Imaging (MRI) contrast agents. The Eu origin may be soil with higher concentration than the crust average.

Effect of humic acid preloading on phosphate adsorption onto zirconium-modified zeolite.

PubMed

Lin, Jianwei; Zhang, Zhe; Zhan, Yanhui

2017-05-01

A zirconium-modified zeolite (ZrMZ) was prepared, and then, humic acid (HA) was immobilized on the ZrMZ surface to prepare HA-loaded ZrMZ (HA-ZrMZ). The obtained ZrMZ and HA-ZrMZ were characterized by energy dispersive X-ray spectroscopy, elemental analyzer, N 2 adsorption/desorption isotherms, pH at the point of zero charge, and X-ray photoelectron spectroscopy. The adsorption characteristics of phosphate on ZrMZ and HA-ZrMZ were comparatively investigated in batch mode. The adsorption mechanism of phosphate on ZrMZ and HA-ZrMZ was investigated by ionic strength effect and 31 P nuclear magnetic resonance. The mechanism for phosphate adsorption onto ZrMZ was the formation of inner-sphere phosphate complexes at the solid/solution interface. The preloading of HA on ZrMZ reduced the phosphate adsorption capacity, and the more the HA loading amount, the lower the phosphate adsorption capacity. However, the preloading of HA on ZrMZ did not change the phosphate adsorption mechanism; i.e., the formation of inner-sphere phosphate surface complexes was still responsible for the adsorption of phosphate on HA-ZrMZ. The decreased phosphate adsorption capacity for ZrMZ after HA coating could be attributed to the fact that the coating of HA on ZrMZ reduced the amount of binding active sites available for phosphate adsorption, changed the adsorbent surface charges, and reduced the specific surface areas and pore volumes of ZrMZ.

Influence of adding strong-carbide-formation elements multiply on particle-reinforced Fe-matrix composite layer produced by laser cladding

NASA Astrophysics Data System (ADS)

Ma, Mingxing; Liu, Wenjin; Zhong, Minlin; Zhang, Hongjun; Zhang, Weiming

2005-01-01

In the research hotspot of particle reinforced metal-matrix composite layer produced by laser cladding, in-situ reinforced particles obtained by adding strong-carbide-formation elements into cladding power have been attracting more attention for their unique advantage. The research has demonstrated that when adding strong-carbide-formation elements-Ti into the cladding powder of the Fe-C-Si-B separately, by optimizing the composition, better cladding coating with the characters of better strength and toughness, higher wear resistance and free of cracks. When the microstructure of cladding coating is hypoeutectic microstructure, its comprehensive performance is best. The research discovered that, compositely adding the strong-carbide-formation elements like Ti+V, Ti+Zr or V+Zr into the cladding coating is able to improve its comprehensive capability. All the cladding coatings obtained are hypoeutectic microstructure. The cladding coatings have a great deal of particulates, and its average microhardness reaches HV0.2700-1400. The research also discovered that the cladding coating obtained is of less cracking after adding the Ti+Zr.

Dual functions of zirconium modification on improving the electrochemical performance of Ni-rich LiNi0.8Co0.1Mn0.1O2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xing; Zhang, Kangjia; Wang, Mingshan

2018-02-28

Trace amount of Zirconium (Zr) has been adopted to modify the crystal structure and surface of the Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material. During cycling at 1.0C, the Zr-modified NCM811 shows an improved capacity retention of 92% after 100 cycles, higher than 75% for pristine NMC811. In addition, the Zr-modified NCM811 is capable of delivering a discharge capacity of 107 mAh g-1 at 10.0C rate, much higher than 28 mAh g-1 delivered by pristine material. These improved electrochemical performances are ascribed to the dual functions of Zr modification. On one hand, part of the Zr enters the crystal lattice, which ismore » beneficial for reducing the Li/Ni cation mixing and enhancing the crystal stability of the cathode. On the other hand, the rest of the Zr forms a 1~2 nm thick coating layer on the surface of the NCM811 cathode, which effectively prevents the direct contact between NCM and the electrolyte, thus suppressing the detrimental interfacial reactions. Therefore, the Zr-modified LiNi0.8Co0.1Mn0.1O2 exhibited significantly enhanced cycling stability and charging/discharging rate capability in comparison with the untreated counterpart.« less

Corrosion behavior and pitting susceptibility of in-situ Ti-based metallic glass matrix composites in 3.5 wt.% NaCl solutions

NASA Astrophysics Data System (ADS)

Xu, K. K.; Lan, A. D.; Yang, H. J.; Han, P. D.; Qiao, J. W.

2017-11-01

The Ti62Zr12V13Cu4Be9, Ti58Zr16V10Cu4Be12, Ti46Zr20V12Cu5Be17, and Ti40Zr24V12Cu5Be19 metallic glass matrix composites (MGMCs) were prepared by copper mould casting. The corrosion resistance and the pitting susceptibility of Ti-based MGMCs were tested on their cross-sectional areas in 3.5 wt.% NaCl solutions by potentiodynamic polarization measurements. The composites with lower Ti contents (Ti40Zr24V12Cu5Be19 and Ti46Zr20V12Cu5Be17) exhibit a low resistance to the chloride induced pitting and local corrosion. The preferential dissolution of amorphous matrix is explained by the high chemical reactivity of beryllium element compared to that of stable dendrites and by the detected lower Ti and V contents. However, fairly good passivity was found in the composite with higher Ti contents (Ti62Zr12V13Cu4Be9). XPS measurements revealed that protective Ti-enriched oxide film was formed on the composite surface, additionally, lower content of beryllium element in amorphous matrix hinder the selective corrosion of amorphous matrix. The assessment of experimental observation leads to a proposed corrosion mechanism involving selective dissolution of amorphous matrix and chloride induced pitting process.

Do s-Process Enhanced Planetary Nebulae Have Unusual Dust Emission Spectra?

NASA Astrophysics Data System (ADS)

Dinerstein, Harriet; Sellgren, Kris; Sterling, Nicholas

2006-05-01

We propose to obtain IRS observations of the mid-infrared dust emission of a sample of Galactic planetary nebulae (PNs) which are known to have enrichments of elements produced in the precursor star by slow neutron-capture nucleosynthesis (the "s-process"). These enhanced abundances result from captures of free neutrons by Fe-peak nuclei following by convective mixing during the AGB; this "third dredge-up" is also responsible for increasing the surface abundance of carbon. Since PNs are the descendants of AGB stars and are often C-rich, it is not surprising that we find substantial enrichments of s-process products such as Ge, Se, and Kr in some PNs. Despite their low initial abundances, 1e-9 to 1e-10 times H, modest enrichments of neutron-capture elements can have observable effects. The spectral type S, a transitional class between O-rich and C-rich AGB stars, is characterized by prominent ZrO bands; Zr is produced in the s-process. We have attempted, without success, to detect gas-phase Zr in PNs. However, Zr is highly refractory. It can condense into ZrO2 or be incorporated into high-temperature rocky condensates in O-rich environments, while in C-rich environments it may form metallic carbides (i.e. ZrC, an analog of TiC). Indeed, Zr-Mo carbide inclusions found in some meteoritic presolar grains are thought to originate in the atmospheres of C-rich AGB stars. Other refractory s-process products (e.g. Sr, Ba) may also be incorporated into grains. High-quality Spitzer spectra of the dust emission in a set of PNs with known s-process enhancements - determined by us from gas-phase measurements of undepleted elements - will be valuable for comparison with laboratory spectroscopy of grain analogs. These comparisons will help determine whether the dredge-up of n-capture products affects the dust chemistry of PNs and may offer some new insights into the dust composition.

Recent Rainfall and Aerosol Chemistry From Bermuda

NASA Astrophysics Data System (ADS)

Landing, W. M.; Shelley, R.; Kadko, D. C.

2014-12-01

This project was devoted to testing the use of Be-7 as a tracer for quantifying trace element fluxes from the atmosphere to the oceans. Rainfall and aerosol samples were collected between June 15, 2011 and July 27, 2013 at the Bermuda Institute of Ocean Sciences (BIOS) located near the eastern end of the island of Bermuda. Collectors were situated near ground level, clear of surrounding vegetation, at a meteorological monitoring station in front of the BIOS laboratory, about 10 m above sea level. This is a Bermuda Air Quality Program site used for ambient air quality monitoring. To quantify the atmospheric deposition of Be-7, plastic buckets were deployed for collection of fallout over ~3 week periods. Wet deposition was collected for trace element analysis using a specially modified "GEOTRACES" N-CON automated wet deposition collector. Aerosol samples were collected with a Tisch TE-5170V-BL high volume aerosol sampler, modified to collect 12 replicate samples on acid-washed 47mm diameter Whatman-41 filters, using procedures identical to those used for the US GEOTRACES aerosol program (Morton et al., 2013). Aerosol and rainfall samples were analyzed for total Na, Mg, Al, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Zr, Cd, Sb, Ba, La, Ce, Nd, Pb, Th, and U using ICPMS. Confirming earlier data from Bermuda, strong seasonality in rainfall and aerosol loading and chemistry was observed, particularly for aerosol and rainfall Fe concentrations when Saharan dust arrives in July/August with SE trajectories.

Microwave-assisted Extraction of Rare Earth Elements from Petroleum Refining Catalysts and Ambient Fine Aerosols Prior to Inductively Coupled Plasma - Mass Spectrometry

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Kulkarni, Pranav; Chellam, Shankar

2006-01-01

In the absence of a certified reference material, a robust microwave-assisted acid digestion procedure followed by inductively coupled plasma - mass spectrometry (ICP-MS) was developed to quantify rare earth elements (REEs) in fluidized-bed catalytic cracking (FCC) catalysts and atmospheric fine particulate matter (PM2.5). High temperature (200 C), high pressure (200 psig), acid digestion (HNO3, HF, and H3BO3) with 20 minute dwell time effectively solubilized REEs from six fresh catalysts, a spent catalyst, and PM2.5. This method was also employed to measure 27 non-REEs including Na, Mg, Al, Si, K, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Zr, Mo, Cd, Cs, Ba, Pb, and U. Complete extraction of several REEs (Y, La, Ce, Pr, Nd, Tb, Dy, and Er) required HF indicating that they were closely associated with the aluminosilicate structure of the zeolite FCC catalysts. Internal standardization using 115In quantitatively corrected non-spectral interferences in the catalyst digestate matrix. Inter-laboratory comparison using ICP-optical emission spectroscopy (ICP-OES) and instrumental neutron activation analysis (INAA) demonstrated the applicability of the newly developed analytical method for accurate analysis of REEs in FCC catalysts. The method developed for FCC catalysts was also successfully implemented to measure trace to ultra-trace concentrations of La, Ce, Pr, Nd, Sm, Gd, Eu, and Dy in ambient PM2.5 in an industrial area of Houston, TX.

The Northeast Kingdom batholith, Vermont: magmatic evolution and geochemical constraints on the origin of Acadian granitic rocks

USGS Publications Warehouse

Ayuso, R.A.; Arth, Joseph G.

1992-01-01

Five Devonian plutons (West Charleston, Echo Pond, Nulhegan, Derby, and Willoughby) that constitute the Northeast Kingdom batholith in Vermont show wide ranges in elemental abundances and ratios consistent with major crustal contributions during their evolution. The batholith consists of metaluminous quartz gabbro, diorite and quartz monzodiorite, peraluminous granodiorite and granite, and strongly peraluminous leucogranite. Contents of major elements vary systematically with increasingSiO40) and have small negative Eu anomalies. The strongly peraluminous Willoughby leucogranite has unique trace-element abundances and ratios relative to the rest of the batholith, including low contents of Hf, Zr, Sr, and Ba, low values of K/Rb (80-164), Th/Ta (<9), Rb/Cs (7-40), K/Cs (0.1-0.5), Ce/Pb (0.5-4), high values of Rb/Sr (1-18) low to moderate REE contents and light-REE enriched patterns (with small negative Eu anomalies). Flat REE patterns (with large negative Eu anomalies) are found in a small, hydrothermally-altered area characterized by high abundances of Sn (up to 26 ppm), Rb (up to 670 ppm), Li (up to 310 ppm), Ta (up to 13.1 ppm), and U (up to 10 ppm). There is no single mixing trend, fractional crystallization assemblage, or assimilationscheme that accounts for all trace elementvariations from quartz gabbro to granite in the Northeast Kingdom batholith. The plutons originated by mixing mantle-derived components and crustal melts generated at different levels in the heterogeneous lithosphere in a continental collisional environment. Hybrid rocks in the batholith evolved by fractional crystallization and assimilation of country rocks (<50% by mass), and some of the leucogranitic rocks were subsequently disturbed by a mild hydrothermal event that resulted in the deposition of small amounts of sulfide minerals. ?? 1992 Springer-Verlag.

New Experimental Constraints on Crystallization Differentiation in a Deep Magma Ocean

NASA Astrophysics Data System (ADS)

Walter, M. J.; Ito, E.; Nakamura, E.; Tronnes, R.; Frost, D.

2001-12-01

Most of Earth's mass probably accreted as a consequence of numerous impacts between large bodies and proto-Earth, and a giant impact with a Mars-sized object is the most plausible explanation for a Moon forming event. 1 Physical models show that large impacts would have caused high-degrees of melting and a global magma ocean. 2 Crystallization differentiation in a deep magma ocean could impart stratification in the solidified mantle, forming large geochemical domains. To accurately model crystallization in a deep magma ocean the liquidus phase-relations of peridotite, as well as mineral/melt element partitioning, must be known at lower mantle conditions. Here, we report the results of liquidus experiments on fertile model peridotite compositions at 23 - 33 GPa. Experiments were performed in 6/8-type multi-anvil apparatus using carbide and sintered-diamond second-stage anvils with 4 and 2 mm truncations, respectively. Samples were encapsulated by either graphite or Re. High-temperatures were generated using LaCrO3 or Re furnaces, and temperatures were held from 2 to 50 minutes at 2300 - 2500 C. Run products were analyzed for major and trace elements using EPMA and SIMS. At 23 GPa the liquidus phase is majorite, followed closely down temperature by ferropericlase (Fp) and Mg-perovskite (Mg-Pv). At 24 GPa the liquidus phase has changed to Fp, followed closely by majorite and Mg-Pv. Ca-perovskite (Ca-Pv) is present only at much lower temperatures close to the solidus. At approximately 31 GPa Mg-Pv is the liquidus phase followed down-temperature by Fp then Ca-Pv. At ~ 33 GPa Ca-Pv crystallizes closer to the liquidus, within about 50 C, at a similar temperature to Fp. Thus, important phases crystallizing in a deep magma ocean are Mg-Pv, Ca-Pv and Fp. Crystallization models based on major element partitioning show that only very modest amounts of crystal separation of a Mg-Pv + Fp assemblage can be tolerated before Ca/Al, Al/Ti and Ca/Ti ratios become unrealistic for estimates of primitive upper mantle (PUM). 3 However, even small amounts of Ca-Pv in the crystal assemblage effectively buffer these ratios at values close to the starting composition (e.g. chondritic). Further, based on our new trace element partitioning data, models involving considerable Mg-Pv fractionation generally show poor matches with model PUM. For example, model PUM has sub-chondritic REE/Ti, whereas these ratios increase considerably during Mg-Pv crystallization. Notable exceptions are super-chondritic Zr/Ti, chondritic Sr/Ti, and sub-chondritic Zr/Nb and Sm/Yb ratios, all of which are well matched by considerable Mg-Pv crystallization. Although trace element D's for Ca-Pv are not yet measured quantitatively, the observed affinity of Ca-Pv for REE could conceivably account for the the sub-chondritic REE/Ti ratios in PUM. Ca-Pv also concentrates K, and could be an important source of heat from radioactive decay in the lower mantle. 1. Canup, R. and Agnor, C., Origin of the Earth and Moon, Righter and Canup, eds., U. Arizona Press, 113-144, 2000. 2. Melosh, H., Origin of the Earth, Newsom and Jones, eds., Oxford Press, 69-84, 1990. 3. McFarlane, E. et al., Geochimica et Cosmochimica Acta, 5161-5172, 1994.

Distribution trends and influence of 4d transition metal elements (Ru, Rh and Pd) doping on mechanical properties and martensitic transformation temperature of B2-ZrCu phase

NASA Astrophysics Data System (ADS)

Guo, Fuda; Zhan, Yongzhong

2017-12-01

The prediction for distribution trends and effect of three 4d transition metal elements (Ru, Rh and Pd) on mechanical properties and martensitic transformation temperature of B2-ZrCu phase were investigated by first-principles calculations. The convex surface of formation energy suggests that the alloying elements prefer to occupy the Cu sites in B2-ZrCu phase and the dopants studied in present are able to strengthen the phase stability. The calculated results of substitutional formation energy suggest that the distribution trend of dopants in B2-ZrCu phase is Ru > Rh > Pd below the dopant concentration 9 at. %, and the distribution trend is Rh > Pd > Ru from 9 at. % to 12.5 at. %. The elastic constants and mechanical properties including bulk modulus and shear modulus were calculated and discussed. The brittleness/ductility characteristic was investigated using the B/G ratio, Poisson's ratio v and Cauchy pressure Cp. The martensitic transformation temperature (Ms) and melting point (Tm) were predicted by using two cubic elastic moduli (C‧ and C44). The prediction results suggest that only the Ms of Zr8Cu7Pd is higher than the parent. The martensitic transformation temperatures of other compounds decrease with the addition of 4d transition metal dopants. Finally, the electronic structures and electron density different were discussed to reveal the bonding characteristics.

Major and trace elements in Mahogany zone oil shale in two cores from the Green River Formation, piceance basin, Colorado

USGS Publications Warehouse

Tuttle, M.L.; Dean, W.E.; Parduhn, N.L.

1983-01-01

The Parachute Creek Member of the lacustrine Green River Formation contains thick sequences of rich oil-shale. The richest sequence and the richest oil-shale bed occurring in the member are called the Mahogany zone and the Mahogany bed, respectively, and were deposited in ancient Lake Uinta. The name "Mahogany" is derived from the red-brown color imparted to the rock by its rich-kerogen content. Geochemical abundance and distribution of eight major and 18 trace elements were determined in the Mahogany zone sampled from two cores, U. S. Geological Survey core hole CR-2 and U. S. Bureau of Mines core hole O1-A (Figure 1). The oil shale from core hole CR-2 was deposited nearer the margin of Lake Uinta than oil shale from core hole O1-A. The major- and trace-element chemistry of the Mahogany zone from each of these two cores is compared using elemental abundances and Q-mode factor modeling. The results of chemical analyses of 44 CR-2 Mahogany samples and 76 O1-A Mahogany samples are summarized in Figure 2. The average geochemical abundances for shale (1) and black shale (2) are also plotted on Figure 2 for comparison. The elemental abundances in the samples from the two cores are similar for the majority of elements. Differences at the 95% probability level are higher concentrations of Ca, Cu, La, Ni, Sc and Zr in the samples from core hole CR-2 compared to samples from core hole O1-A and higher concentrations of As and Sr in samples from core hole O1-A compared to samples from core hole CR-2. These differences presumably reflect slight differences in depositional conditions or source material at the two sites. The Mahogany oil shale from the two cores has lower concentrations of most trace metals and higher concentrations of carbonate-related elements (Ca, Mg, Sr and Na) compared to the average shale and black shale. During deposition of the Mahogany oil shale, large quantities of carbonates were precipitated resulting in the enrichment of carbonate-related elements and dilution of most trace elements as pointed out in several previous studies. Q-mode factor modeling is a statistical method used to group samples on the basis of compositional similarities. Factor end-member samples are chosen by the model. All other sample compositions are represented by varying proportions of the factor end-members and grouped as to their highest proportion. The compositional similarities defined by the Q-mode model are helpful in understanding processes controlling multi-element distributions. The models for each core are essentially identical. A four-factor model explains 70% of the variance in the CR-2 data and 64% of the O1-A data (the average correlation coefficients are 0. 84 and 0. 80, respectively). Increasing the number of factors above 4 results in the addition of unique instead of common factors. Table I groups the elements based on high factor-loading scores (the amount of influence each element has in defining the model factors). Similar elemental associations are found in both cores. Elemental abundances are plotted as a function of core depth using a five-point weighted moving average of the original data to smooth the curve (Figure 3 and 4). The plots are grouped according to the four factors defined by the Q-mode models and show similar distributions for elements within the same factor. Factor 1 samples are rich in most trace metals. High oil yield and the presence of illite characterize the end-member samples for this factor (3, 4) suggesting that adsorption of metals onto clay particles or organic matter is controlling the distribution of the metals. Precipitation of some metals as sulfides is possible (5). Factor 2 samples are high in elements commonly associated with minerals of detrital or volcanogenic origin. Altered tuff beds and lenses are prevalent within the Mahogany zone. The CR-2 end-member samples for this factor contain analcime (3) which is an alteration product within the tuff beds of the Green River Formation. Th

Inclusions of crichtonite-group minerals in Cr-pyropes from the Internatsionalnaya kimberlite pipe, Siberian Craton: Crystal chemistry, parageneses and relationships to mantle metasomatism

NASA Astrophysics Data System (ADS)

Rezvukhin, Dmitriy I.; Malkovets, Vladimir G.; Sharygin, Igor S.; Tretiakova, Irina G.; Griffin, William L.; O'Reilly, Suzanne Y.

2018-05-01

Cr-pyrope xenocrysts and associated inclusions of crichtonite-group minerals from the Internatsionalnaya kimberlite pipe were studied to provide new insights into processes in the lithospheric mantle beneath the Mirny kimberlite field, Siberian craton. Pyropes are predominantly of lherzolitic paragenesis (Cr2O3 2-6 wt%) and have trace-element spectra typical for garnets from fertile mantle (gradual increase in chondrite-normalized values from LREE to MREE-HREE). Crichtonite-group minerals commonly occur as monomineralic elongated inclusions, mostly in association with rutile, Mg-ilmenite and Cr-spinel within individual grains of pyrope. Sample INT-266 hosts intergrowth of crichtonite-group mineral and Cl-apatite, while sample INT-324 contains polymineralic apatite- and dolomite-bearing assemblages. Crichtonite-group minerals are Al-rich (1.1-4.5 wt% Al2O3), moderately Zr-enriched (1.3-4.3 wt% ZrO2), and are Ca-, Sr-, and occasionally Ba-dominant in terms of A-site occupancy; they also contain significant amounts of Na and LREE. T-estimates and chemical composition of Cr-pyropes imply that samples represent relatively low-T peridotite assemblages with ambient T ranging from 720 to 820°С. Projected onto the 35 mW/m2 cratonic paleogeotherm for the Mirny kimberlite field (Griffin et al., 1999b. Tectonophysics 310, 1-35), temperature estimates yield a P range of 34-42 kbar ( 110-130 km), which corresponds to a mantle domain in the uppermost part of the diamond stability field. The presence of crichtonite-group minerals in Cr-pyropes has petrological and geochemical implications as evidence for metasomatic enrichment of some incompatible elements in the lithospheric mantle beneath the Mirny kimberlite field. The genesis of Cr-pyropes with inclusions of crichtonite-group minerals is attributed to the percolation of Ca-Sr-Na-LREE-Zr-bearing carbonate-silicate metasomatic agents through Mg- and Cr-rich depleted peridotite protoliths. The findings of several potentially new members of the crichtonite group as inclusions in garnet extend existing knowledge on the compositions and occurrences of exotic titanates stable in the lithospheric mantle.

Trace element distribution in waters of the northern catchment area of Lake Linneret, northern Israel

NASA Astrophysics Data System (ADS)

Sandler, A.; Brenner, I. B.; Halicz, L.

1988-02-01

Waters of the northern watershed of Lake Kineret, sampled during the period 1978 1983, were analyzed for their major and trace element contents. The trace element concentrations of the major water sources of the watershed (the Dan and Banias springs) represent background values. After emergence, the waters are subjected to human activity. In crossing the populated and cultivated Hula Basin in man-made canals, the major and trace element contents increase. In comparison to the trace element concentrations, those of the major elements have narrow ranges and small temporal fluctuations. Trace element concentrations varied by 3 orders of magnitude, and temporal variations were large but not neccessarily seasonal. Point sources of trace elements were urban effluents, fish pond wastes, and peat soil drainage. The trace element concentrations decrease in the waters of the last segment of the Jordan River. All measured trace elements were below the criteria levels established by regulatory agencies. Several, however, were of the same order of magnitude. Addition of wastes from enhanced recycling, and morphologic modification of the final course of the Jordan River could result in increase in the trace element concentrations in the water.

Thermal stability and specular reflection behaviour of CoNbZr-based bottom spin valves with nano-oxide layer

NASA Astrophysics Data System (ADS)

Kim, Jong Soo; Lee, Seong-Rae

2004-06-01

The thermal stability and specularity aspects of a CoNbZr-based bottom spin valve (SV) employing a nano-oxide layer (NOL) were investigated. The magnetoresistance (MR) ratio of the as-deposited CoNbZr-based bottom SV increased by 62% (from 6.3 to 10.2%) with incorporation of the NOL. The enhancement of the MR ratio was considered to be due to the specular effect ( increased from 0.722 to 1.363 cm) of the NOL. The MR ratio of a Ta-based bottom SV decreased by about 45% (from 6.9 to 3.8%) when the samples were annealed at 300 °C for 240 min. By contrast, the MR ratio of the CoNbZr-based bottom SV with NOL increase d by 14 % (from 10.2 to 11.7%). The root mean square roughness value of the CoNbZr layer (0.07 nm) was superior to that of the Ta layer (0.43 nm). Although Mn in IrMn diffused out to the surface through the active layers resulting in the formation of Mn oxide at the surface in the CoNbZr-based bottom SV, no trace of Mn was found in the active layers and no significant degradation occurred.

The Source of Volcanic Ash in Late Classic Maya Pottery at El Pilar, Belize

NASA Astrophysics Data System (ADS)

Catlin, B. L.; Ford, A.; Spera, F. J.

2007-12-01

The presence of volcanic ash used as temper in Late Classic Maya pottery (AD 600-900) at El Pilar has been long known although the volcano(s) contributing ash have not been identified. We use geochemical fingerprinting, comparing compositions of glass shards in potsherds with volcanic sources to identify the source(s). El Pilar is located in the Maya carbonate lowlands distant from volcanic sources. It is unlikely Maya transported ash from distant sites: ash volumes are too large, the terrain too rugged, and no draft animals were available. Ash layer mining is unlikely because mine sites have not been found despite intensive surveys. Nearest volcanic sources to El Pilar, Belize and Guatemala, are roughly 450 km to the south and east. The ash found in potsherds has a cuspate morphology. This suggests ash was collected during, or shortly after, an ash airfall event following eruption. Analyses of n=333 ash shards from 20 ceramic (pottery) sherds was conducted by electron microprobe for major elements, and LA-ICPMS for trace elements and Pb isotopes. These analyses can be compared to volcanic materials from candidate volcanoes in the region. The 1982 El Chichon eruption caused airfall deposition (< 1 mm isopach) at El Pilar which lead Espindola et. al, 2000 to suggest that earlier eruptions at El Chichon could have caused ash fall at El Pilar during the Late Classic. 333 individual glass shards found within about 20 distinct potsherds have a mean silica content of 78.3±1.1 wt. % (one-sigma). The 1982 El Chichon eruption products have a mean silica content of 60.2±7.2% (one-sigma, n=48); the circa 1475 AD eruptive products of El Chichon have a mean silica content of 53.4±3.4 wt % (one-sigma, n=8). This suggests that El Chichon was not a source of the ash at El Pilar. In order confirm or refute the El Chichon source hypothesis, comparison of trace element ratios between archaeological samples and El Chichon has been made. The atomic ratios of La/Yb, Nb/Ta, Zr/Hf, Sr/Ba and Th/U of n=215 glass shards in the potsherds are 12.2±7.1, 10.9±3.4, 31.2±11.5, 0.09±0.05 and 2.5±0.9, respectively. These ratios for 1982 El Chichon are 15.4±2.1, 26.3, 36.1±5.3, 1.4±0.06 and 3.16, respectively. Data for the 1475 AD El Chichon eruption (Macias et al, 2003) can also be compared; the ratios from are 13.2±2.2, 7.3±1.8, 30.4±9.6, 1.51±0.4 and 2.88±0.23, respectively. The mean 208Pb/206Pb ratio of n=5 potsherds is 2.0523±0.002 compared to 2.0514±0.00074 for n=7 samples from El Chichon. The two most recent eruptions from El Chichon overlap with the potsherd glass data except for Sr/Ba, which might be modified by Sr-Ca exchange during firing. In order to test the effects of pot firing on glass compositional changes, experiments were conducted in which high silica volcanic glass was fired with clay according to heating schedules used by Maya potters. Two important changes are that Na is rapidly lost preferentially to K and that the Si/Ca ratio decreases due to Ca diffusion from matrix into glass during firing. One expects that ratios of the refractory trace elements such as La/Yb and Zr/Hf are less susceptible to modification. Further experiments of trace element mobility during firing are underway.

Numerical simulation of trace element transport on subsurface environment pollution in coal mine spoil.

PubMed

Qiang, Xue; Bing, Liang; Hui-yun, Wang; Lei, Liu

2006-01-01

An understanding of the dynamic behavior of trace elements leaching from coal mine spoil is important in predicting the groundwater quality. The relationship between trace element concentrations and leaching times, pH values of the media is studied. Column leaching tests conducted in the laboratory showed that there was a close correlation between pH value and trace element concentrations. The longer the leaching time, the higher the trace element concentrations. Different trace elements are differently affected by pH values of leaching media. A numerical model for water flow and trace element transport has been developed based on analyzing the characteristics of migration and transformation of trace elements leached from coal mine spoil. Solutions to the coupled model are accomplished by Eulerian-Lagrangian localized adjoint method. Numerical simulation shows that rainfall intensity determined maximum leaching depth. As rainfall intensity is 3.6ml/s, the outflow concentrations indicate a breakthrough of trace elements beyond the column base, with peak concentration at 90cm depth. And the subsurface pollution range has a trend of increase with time. The model simulations are compared to experimental results of trace element concentrations, with reasonable agreement between them. The analysis and modeling of trace elements suggested that the infiltration of rainwater through the mine spoil might lead to potential groundwater pollution. It provides theoretical evidence for quantitative assessment soil-water quality of trace element transport on environment pollution.

Trace elements in fish from Taihu Lake, China: levels, associated risks, and trophic transfer.

PubMed

Hao, Ying; Chen, Liang; Zhang, Xiaolan; Zhang, Dongping; Zhang, Xinyu; Yu, Yingxin; Fu, Jiamo

2013-04-01

Concentrations of eight trace elements [iron (Fe), manganese (Mn), zinc (Zn), chromium (Cr), mercury (Hg), cadmium (Cd), lead (Pb), and arsenic (As)] were measured in a total of 198 samples covering 24 fish species collected from Taihu Lake, China, in September 2009. The trace elements were detected in all samples, and the total mean concentrations ranged from 18.2 to 215.8 μg/g dw (dry weight). The concentrations of the trace elements followed the sequence of Zn>Fe>Mn>Cr>As>Hg>Pb>Cd. The measured trace element concentrations in fish from Taihu Lake were similar to or lower than the reported values in fish around the world. The metal pollution index was used to compare the total trace element accumulation levels among various species. Toxabramis swinhonis (1.606) accumulated the highest level of the total trace elements, and Saurogobio dabryi (0.315) contained the lowest. The concentrations of human non-essential trace elements (Hg, Cd, Pb, and As) were lower than the allowable maximum levels in fish in China and the European Union. The relationships between the trace element concentrations and the δ(15)N values of fish species were used to investigate the trophic transfer potential of the trace elements. Of the trace elements, Hg might be biomagnified through the food chain in Taihu Lake if the significant level of p-value was set at 0.1. No biomagnification and biodilution were observed for other trace elements. Copyright © 2012 Elsevier Inc. All rights reserved.

Advanced source apportionment of size-resolved trace elements at multiple sites in London during winter

DOE PAGES

Visser, S.; Slowik, Jay G.; Furger, M.; ...

2015-10-12

Here, trace element measurements in PM 10–2.5, PM 2.5–1.0 and PM 1.0–0.3 aerosol were performed with 2 h time resolution at kerbside, urban background and rural sites during the ClearfLo winter 2012 campaign in London. The environment-dependent variability of emissions was characterized using the Multilinear Engine implementation of the positive matrix factorization model, conducted on data sets comprising all three sites but segregated by size. Combining the sites enabled separation of sources with high temporal covariance but significant spatial variability. Separation of sizes improved source resolution by preventing sources occurring in only a single size fraction from having too smallmore » a contribution for the model to resolve. Anchor profiles were retrieved internally by analysing data subsets, and these profiles were used in the analyses of the complete data sets of all sites for enhanced source apportionment. A total of nine different factors were resolved (notable elements in brackets): in PM 10–2.5, brake wear (Cu, Zr, Sb, Ba), other traffic-related (Fe), resuspended dust (Si, Ca), sea/road salt (Cl), aged sea salt (Na, Mg) and industrial (Cr, Ni); in PM 2.5–1.0, brake wear, other traffic-related, resuspended dust, sea/road salt, aged sea salt and S-rich (S); and in PM 1.0–0.3, traffic-related (Fe, Cu, Zr, Sb, Ba), resuspended dust, sea/road salt, aged sea salt, reacted Cl (Cl), S-rich and solid fuel (K, Pb). Human activities enhance the kerb-to-rural concentration gradients of coarse aged sea salt, typically considered to have a natural source, by 1.7–2.2. These site-dependent concentration differences reflect the effect of local resuspension processes in London. The anthropogenically influenced factors traffic (brake wear and other traffic-related processes), dust and sea/road salt provide further kerb-to-rural concentration enhancements by direct source emissions by a factor of 3.5–12.7. The traffic and dust factors are mainly emitted in PM 10–2.5 and show strong diurnal variations with concentrations up to 4 times higher during rush hour than during night-time. Regionally influenced S-rich and solid fuel factors, occurring primarily in PM 1.0–0.3, have negligible resuspension influences, and concentrations are similar throughout the day and across the regions.« less

Advanced source apportionment of size-resolved trace elements at multiple sites in London during winter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Visser, S.; Slowik, Jay G.; Furger, M.

Here, trace element measurements in PM 10–2.5, PM 2.5–1.0 and PM 1.0–0.3 aerosol were performed with 2 h time resolution at kerbside, urban background and rural sites during the ClearfLo winter 2012 campaign in London. The environment-dependent variability of emissions was characterized using the Multilinear Engine implementation of the positive matrix factorization model, conducted on data sets comprising all three sites but segregated by size. Combining the sites enabled separation of sources with high temporal covariance but significant spatial variability. Separation of sizes improved source resolution by preventing sources occurring in only a single size fraction from having too smallmore » a contribution for the model to resolve. Anchor profiles were retrieved internally by analysing data subsets, and these profiles were used in the analyses of the complete data sets of all sites for enhanced source apportionment. A total of nine different factors were resolved (notable elements in brackets): in PM 10–2.5, brake wear (Cu, Zr, Sb, Ba), other traffic-related (Fe), resuspended dust (Si, Ca), sea/road salt (Cl), aged sea salt (Na, Mg) and industrial (Cr, Ni); in PM 2.5–1.0, brake wear, other traffic-related, resuspended dust, sea/road salt, aged sea salt and S-rich (S); and in PM 1.0–0.3, traffic-related (Fe, Cu, Zr, Sb, Ba), resuspended dust, sea/road salt, aged sea salt, reacted Cl (Cl), S-rich and solid fuel (K, Pb). Human activities enhance the kerb-to-rural concentration gradients of coarse aged sea salt, typically considered to have a natural source, by 1.7–2.2. These site-dependent concentration differences reflect the effect of local resuspension processes in London. The anthropogenically influenced factors traffic (brake wear and other traffic-related processes), dust and sea/road salt provide further kerb-to-rural concentration enhancements by direct source emissions by a factor of 3.5–12.7. The traffic and dust factors are mainly emitted in PM 10–2.5 and show strong diurnal variations with concentrations up to 4 times higher during rush hour than during night-time. Regionally influenced S-rich and solid fuel factors, occurring primarily in PM 1.0–0.3, have negligible resuspension influences, and concentrations are similar throughout the day and across the regions.« less

Isotopic and trace element variations in the Ruby Batholith, Alaska, and the nature of the deep crust beneath the Ruby and Angayucham Terranes

USGS Publications Warehouse

Arth, Joseph G.; Zmuda, Clara C.; Foley, Nora K.; Criss, Robert E.; Patton, W.W.; Miller, T.P.

1989-01-01

Thirty-six samples from plutons of the Ruby batholith of central Alaska were collected and analyzed for 22 trace elements, and many were analyzed for the isotopic compositions of Sr, Nd, O, and Pb in order to delimit the processes that produced the diversity of granodioritic to granitic compositions, to deduce the nature of the source of magmas at about 110 Ma, and to characterize the deep crust beneath the Ruby and Angayucham terranes. Plutons of the batholith show a substantial range in initial 87Sr/86Sr (SIR) of 0.7055–0.7235 and a general decrease from southwest to northeast. Initial 143Nd/144Nd (NIR) have a range of 0.51150–0.51232 and generally increase from southwest to northeast. The δ18O values for most whole rocks have a range of +8.4 to +11.8 and an average of +10.3‰. Rb, Cs, U, and Th show large ranges of concentration, generally increase as SiO2 increases, and are higher in southwest than in northeast plutons. Sr, Ba, Zr, Hf, Ta, Sc, Cr, Co, and Zr show large ranges of concentration and generally decrease as SiO2 increases. Rare earth elements (REE) show fractionated patterns and negative Eu anomalies. REE concentrations and anomalies are larger in the southwest than in the northeast plutons. Uniformity of SIR and NIR in Sithylemenkat and Jim River plutons suggests a strong role for fractional crystallization or melting of uniform magma sources at depth. Isotopic variability in Melozitna, Ray Mountains, Hot Springs, and Kanuti plutons suggests complex magmatic processes such as magma mixing and assimilation, probably combined with fractional crystallization, or melting of a complex source at depth. The large variations in SIR and NIR in the batholith require a variation in source materials at depth. The southwestern plutons probably had dominantly siliceous sources composed of metamorphosed Proterozoic and Paleozoic upper crustal rocks. The northeastern plutons probably had Paleozoic sources that were mixtures of siliceous and intermediate to mafic crustal rocks. The inferred sources could well have been the higher-metamorphic-grade lithologic equivalents of the exposed Proterozoic(?) to Paleozoic schists, orthogneisses, and metavolcanic rocks of Ruby terrane, the silicic portions of which are quite radiogenic. The deeper crustal sources that gave rise to most of the batholithic magmas are inferred to be similar under both the Ruby metamorphic terrane and the Angayucham ophiolitic terrane.

Recycling of trace elements required for humans in CELSS.

PubMed

Ashida, A

1994-11-01

Recycle of complete nourishment necessary for human should be constructed in CELSS (Controlled Ecological Life Support Systems). Essential elements necessary for human support are categorized as major elements, semi-major elements and trace elements. Recently, trace elements have been identified from considerations of local diseases, food additive problems, pollution problems and adult diseases, consisting of Fe, Zn, Cu, Se, Co, F, Si, Mn, Cr, I, As, Mo, Ni, V, Sn, Li, Br, Cd, Pb, B. A review of the biogeochemical history of the earth's biosphere and the physiological nature of humans and plants explains some of the requirements. A possible route for intake of trace elements is considered that trace elements are dissolved in some chemical form in water, absorbed by plants through their roots and then transfered to human as foods. There may be a possibility that living things absorb some trace elements from atmosphere. Management and recycling of trace elements in CELSS is discussed.

Recycling of trace elements required for humans in CELSS

NASA Astrophysics Data System (ADS)

Ashida, A.

1994-11-01

Recycle of complete nourishment necessary for human should be constructed in CELSS (Controlled Ecological Life Support Systems). Essential elements necessary for human support are categorized as major elements, semi-major elements and trace elements. Recently, trace elements have been identified from considerations of local diseases, food additive problems, pollution problems and adult diseases, consisting of Fe, Zn, Cu, Se, Co, F, Si, Mn, Cr, I, As, Mo, Ni, V, Sn, Li, Br, Cd, Pb, B. A review of the biogeochemical history of the earth's biosphere and the physiological nature of humans and plants explains some of the requirements. A possible route for intake of trace elements is considered that trace elements are dissolved in some chemical form in water, absorbed by plants through their roots and then transfered to human as foods. There may be a posibility that living things absorb some trace elements from atmosphere. Management and recycling of trace elements in CELSS is discussed.

Trace Elements in River Waters

NASA Astrophysics Data System (ADS)

Gaillardet, J.; Viers, J.; Dupré, B.

2003-12-01

Trace elements are characterized by concentrations lower than 1 mg L-1 in natural waters. This means that trace elements are not considered when "total dissolved solids" are calculated in rivers, lakes, or groundwaters, because their combined mass is not significant compared to the sum of Na+, K+, Ca2+, Mg2+, H4SiO4, HCO3-, CO32-, SO42-, Cl-, and NO3-. Therefore, most of the elements, except about ten of them, occur at trace levels in natural waters. Being trace elements in natural waters does not necessarily qualify them as trace elements in rocks. For example, aluminum, iron, and titanium are major elements in rocks, but they occur as trace elements in waters, due to their low mobility at the Earth's surface. Conversely, trace elements in rocks such as chlorine and carbon are major elements in waters.The geochemistry of trace elements in river waters, like that of groundwater and seawater, is receiving increasing attention. This growing interest is clearly triggered by the technical advances made in the determination of concentrations at lower levels in water. In particular, the development of inductively coupled plasma mass spectrometry (ICP-MS) has considerably improved our knowledge of trace-element levels in waters since the early 1990s. ICP-MS provides the capability of determining trace elements having isotopes of interest for geochemical dating or tracing, even where their dissolved concentrations are extremely low.The determination of trace elements in natural waters is motivated by a number of issues. Although rare, trace elements in natural systems can play a major role in hydrosystems. This is particularly evident for toxic elements such as aluminum, whose concentrations are related to the abundance of fish in rivers. Many trace elements have been exploited from natural accumulation sites and used over thousands of years by human activities. Trace elements are therefore highly sensitive indexes of human impact from local to global scale. Pollution impact studies require knowledge of the natural background concentrations and knowledge of pollutant behavior. For example, it is generally accepted that rare earth elements (REEs) in waters behave as good analogues for the actinides, whose natural levels are quite low and rarely measured. Water quality investigations have clearly been a stimulus for measurement of toxic heavy metals in order to understand their behavior in natural systems.From a more fundamental point of view, it is crucial to understand the behavior of trace elements in geological processes, in particular during chemical weathering and transport by waters. Trace elements are much more fractionated by weathering and transport processes than major elements, and these fractionations give clues for understanding the nature and intensity of the weathering+transport processes. This has not only applications for weathering studies or for the past mobilization and transport of elements to the ocean (potentially recorded in the sediments), but also for the possibility of better utilization of trace elements in the aqueous environment as an exploration tool.In this chapter, we have tried to review the recent literature on trace elements in rivers, in particular by incorporating the results derived from recent ICP-MS measurements. We have favored a "field approach" by focusing on studies of natural hydrosystems. The basic questions which we want to address are the following: What are the trace element levels in river waters? What controls their abundance in rivers and fractionation in the weathering+transport system? Are trace elements, like major elements in rivers, essentially controlled by source-rock abundances? What do we know about the chemical speciation of trace elements in water? To what extent do colloids and interaction with solids regulate processes of trace elements in river waters? Can we relate the geochemistry of trace elements in aquatic systems to the periodic table? And finally, are we able to satisfactorily model and predict the behavior of most of the trace elements in hydrosystems?An impressive literature has dealt with experimental works on aqueous complexation, uptake of trace elements by surface complexation (inorganic and organic), uptake by living organisms (bioaccumulation) that we have not reported here, except when the results of such studies directly explain natural data. As continental waters encompass a greater range of physical and chemical conditions, we focus on river waters and do not discuss trace elements in groundwaters, lakes, and the ocean. In lakes and in the ocean, the great importance of life processes in regulating trace elements is probably the major difference from rivers.Section 5.09.2 of this chapter reports data. We will review the present-day literature on trace elements in rivers to show that our knowledge is still poor. By comparing with the continental abundances, a global mobility index is calculated for each trace element. The spatial and temporal variability of trace-element concentrations in rivers will be shown to be important. In Section 5.09.3, sources of trace elements in river waters are indicated. We will point out the great diversity of sources and the importance of global anthropogenic contamination for a number of elements. The question of inorganic and organic speciation of trace elements in river water will then be addressed in Section 5.09.4, considering some general relationships between speciation and placement in the periodic table. In Section 5.09.5, we will show that studies on organic-rich rivers have led to an exploration of the "colloidal world" in rivers. Colloids are small particles, passing through the conventional filters used to separate dissolved and suspended loads in rivers. They appear as major carriers of trace elements in rivers and considerably complicate aqueous-speciation calculation. Finally, in Section 5.09.6, the significance of interactions between solutes and solid surfaces in river waters will be reviewed. Regulation by surfaces is of major importance for a great range of elements. Although for both colloids and surface interactions, some progress has been made, we are still far from a unified model that can accurately predict trace-element concentrations in natural water systems. This is mainly due to our poor physical description of natural colloids, surface site complexation, and their interaction with solutes.

Geochemical Composition of Volcanic Rocks from the May 2003 Eruption of Anatahan Volcano, Mariana Islands

NASA Astrophysics Data System (ADS)

Wade, J. A.; Plank, T.; Stern, R.; Hilton, D.; Fischer, T. P.; Moore, R.; Trusdell, F.; Sako, M.

2003-12-01

The first historical eruption of Anatahan volcano began on May 10, 2003, from the easternmost of the island's two craters. Samples of tephra, scoria, and bombs, collected in May by a MARGINS-supported rapid-response team, were analyzed for 34 trace elements by solution ICP-MS at Boston University and Sr-Nd-Pb isotopic composition at the University of Texas-Dallas. The new eruptive materials can be compared with an extensive suite of pre-existing volcanics (basalts through dacites) from Anatahan sampled by the USGS in 1990 and 1992, and analyzed by XRF and INAA. While most Mariana volcanoes erupt basalts and basaltic andesites, Anatahan is unusual for erupting a wide range of compositions, from basalt to dacite, and thus provides the best opportunity for addressing questions of magma evolution in this classic island arc. The newly erupted scoria and pumice are andesites and dacites that are among the most silicic materials erupted in the northern Mariana islands. The recent eruptives are highly homogeneous; 13 samples vary by only 3-5% relative standard deviation for incompatible trace elements. Isotopic compositions (0.703450 +/- 2 87Sr/86Sr and 18.806 +/- 5 206Pb/204Pb) are within the range of previously measured samples from Anatahan and other volcanic centers in the Marianas. The combined dataset for Anatahan defines virtually a single liquid line of descent. This is consistent with nearly-parallel REE patterns, and small variations in the ratios of the most incompatible trace elements (e.g., Th/Rb varies by <10% over the entire fractionation trend). Low values of Th/La and Th/Zr in Anatahan volcanics provide evidence against partial melting of crustal material as a source of the silicic magmas, as these ratios are highly senstive to apatite- and zircon- saturated crustal melts. Instead, the basalts, andesites and dacites of Anatahan appear to be related predominantly by crystal fractionation with little evidence for assimilation of crustal melts. The new data can also be used to make new inferences as to the source characteristics of Anatahan magma. Trace element ratios Th/La and Sm/La distinguish island-to-island differences in the subducted sediment components incorporated into the Mariana arc magmas. Most Mariana volcanics plot on a mixing line between depleted mantle and the bulk subducting sediment Th/La (0.14). Anatahan, however, mixes to slightly higher Th/La (0.16), which could be caused by the shallow loss of the top 50 m of the sedimentary column (pelagic clay) during subduction.

The role of the seagrass Posidonia oceanica in the cycling of trace elements

NASA Astrophysics Data System (ADS)

Sanz-Lázaro, C.; Malea, P.; Apostolaki, E. T.; Kalantzi, I.; Marín, A.; Karakassis, I.

2012-03-01

The aim of this work was to study the role of the seagrass Posidonia oceanica on the cycling of a wide set of trace elements (Ag, As, Ba, Bi, Cd, Co, Cr, Cs, Cu, Fe, Ga, Li, Mn, Ni, Pb, Rb, Sr, Tl, V and Zn). We measured the concentration of these trace elements in the different compartments of P. oceanica (leaves, rhizomes, roots and epibiota) in a non-polluted seagrass meadow representative of the Mediterranean and calculated the annual budget from a mass balance. We provide novel data on accumulation dynamics of many trace elements in P. oceanica compartments and demonstrate that trace element accumulation patterns are mainly determined by plant compartment rather than by temporal variability. Epibiota was the compartment which showed the greatest concentrations for most trace elements. Thus, they constitute a key compartment when estimating trace element transfer to higher trophic levels by P. oceanica. For most trace elements, translocation seemed to be low and acropetal. Zn, Cd, Sr and Rb were the trace elements that showed the highest release rate through decomposition of plant detritus, while Cs, Tl and Bi the lowest. P. oceanica acts as a sink of potentially toxic trace elements (Ni, Cr, As and Ag), which can be sequestered, decreasing their bioavailability. P. oceanica may have a relevant role in the cycling of trace elements in the Mediterranean.

The role of the seagrass Posidonia oceanica in the cycling of trace elements

NASA Astrophysics Data System (ADS)

Sanz-Lázaro, C.; Malea, P.; Apostolaki, E. T.; Kalantzi, I.; Marín, A.; Karakassis, I.

2012-07-01

The aim of this study was to investigate the role of the seagrass Posidonia oceanica on the cycling of a wide set of trace elements (Ag, As, Ba, Bi, Cd, Co, Cr, Cs, Cu, Fe, Ga, Li, Mn, Ni, Pb, Rb, Sr, Tl, V and Zn). We measured the concentration of these trace elements in different compartments of P. oceanica (leaves, rhizomes, roots and epiphytes) in a non-polluted seagrass meadow representative of the Mediterranean and calculated the annual budget from a mass balance. We provide novel data on accumulation dynamics of many trace elements in P. oceanica compartments and demonstrate that trace element accumulation patterns are mainly determined by plant compartment rather than by temporal variability. Epiphytes were the compartment, which showed the greatest concentrations for most trace elements. Thus, they constitute a key compartment when estimating trace element transfer to higher trophic levels by P. oceanica. Trace element translocation in P. oceanica seemed to be low and acropetal in most cases. Zn, Cd, Sr and Rb were the trace elements that showed the highest release rate through decomposition of plant detritus, while Cs, Tl and Bi showed the lowest. P. oceanica acts as a sink of potentially toxic trace elements (Ni, Cr, As and Ag), which can be sequestered, decreasing their bioavailability. P. oceanica may have a relevant role in the cycling of trace elements in the Mediterranean.

Trace Elements and Healthcare: A Bioinformatics Perspective.

PubMed

Zhang, Yan

2017-01-01

Biological trace elements are essential for human health. Imbalance in trace element metabolism and homeostasis may play an important role in a variety of diseases and disorders. While the majority of previous researches focused on experimental verification of genes involved in trace element metabolism and those encoding trace element-dependent proteins, bioinformatics study on trace elements is relatively rare and still at the starting stage. This chapter offers an overview of recent progress in bioinformatics analyses of trace element utilization, metabolism, and function, especially comparative genomics of several important metals. The relationship between individual elements and several diseases based on recent large-scale systematic studies such as genome-wide association studies and case-control studies is discussed. Lastly, developments of ionomics and its recent application in human health are also introduced.

Inter- and intra-group compositional variations in Apollo 15 pyroclastic green glass - An electron- and ion-microprobe study

NASA Technical Reports Server (NTRS)

Galbreath, K. C.; Shearer, C. K.; Papike, J. J.; Shimizu, N.

1990-01-01

Results are presented on major- and trace-element abundance analyses of Apollo 15 pyroclastic green glasses from groups A, B, C, D, and E, carried out using electron- and ion-microprobe techniques. The diagrams depicting Sr, Zr, Ba, and Nd vs Co variations indicate the presence of a high-Co trend in groups A and D and a low-Co trend in groups B and C. Group-E glasses were found to be significantly enriched in Sr, relative to the other four glass groups. Chemical data of this study were integrated with previous data to evaluate various magmatic processes that have been proposed in the past to explain chemical variations in the lunar green glass. Results of calculations using a source mixing model suggest that the Apollo 15 green glasses represent multiple eruptive events from three chemically distinct but compositionally variable source regions.

Tracing the Chemical Evolution of Metal-rich Galactic Bulge Globular Clusters

NASA Astrophysics Data System (ADS)

Munoz Gonzalez, Cesar; Saviane, Ivo; Geisler, Doug; Villanova, Sandro

2018-01-01

We present in this poster the metallicity characterization of the four metal rich Bulge Galactic Gobular Clusters, which have controversial metallicities. We analyzed our high-resolution spectra (using UVES-580nm and GIRAFFE-HR13 setups) for a large sample of RGB/AGB targets in each cluster in order to measure their metallicity and prove or discard the iron spread hypothesis. We have also characterized chemically stars with potentially different iron content by measuring light (O, Na, Mg, Al), alpha (Si, Ca, Ti), iron–peak (V, Cr, Ni, Mn) and s and r process (Y, Zr, Ba, Eu) elements. We have identified possible channels responsible for the chemical heterogeneity of the cluster populations, like AGB or massive fast-rotating stars contamination, or SN explosion. Also, we have analyzed the origin and evolution of these bulge GCs and their connection with the bulge itself.

Investigation of the fracture mechanics of boride composites

NASA Technical Reports Server (NTRS)

Clougherty, E. V.; Pober, R. L.; Kaufman, L.

1972-01-01

Significant results were obtained in fabrication studies of the role of metallic additives of Zr, Ti, Ni, Fe and Cr on the densification of ZrB2. All elemental additions lower the processing temperatures required to effect full densification of ZrB2. Each addition effects enhanced densification by a clearly distinguishable and different mechanism and the resulting fabricated materials are different. A significant improvement in strength and fracture toughness was obtained for the ZrB2/Ti composition. Mechanical characterization studies for the ZrB2/SiC/C composites and the new ZrB2/Metal materials produced data relevant to the effect of impacting load on measured impact energies, a specimen configuration for which controlled fracture could occur in a suitably hard testing apparatus, and fracture strength data. Controlled fracture--indicative of measurable fracture toughness--was obtained for the ZrB2-SiC-C composite, and a ZrB2/Ti composite fabricated from ZrB2 with an addition of 30 weight per cent Ti. The increased strength and toughness of the ZrB2/Ti composite is consistent with the presence of a significantly large amount of a fine grained acicular phase formed by reaction of Ti with ZrB2 during processing.

Chemical and Physical Weathering of Granites in a Semi-Arid Savanna

NASA Astrophysics Data System (ADS)

Khomo, L.; Hartshorn, A.; Chadwick, O.; Kurtz, A.; Heimsath, A.; Rogers, K.

2005-12-01

The catena concept describes soil properties on hillslopes and implies a hydrological mass redistribution process that has been applied differently in different parts of the Earth. In tectonically active regions, it is mostly used to describe the redistribution of mass by overland flow leading to thickening soil mantles downslope. This application is somewhat different from its initial and still popular usage in tectonically inactive areas of Africa, where it defines long-term soil property differentiation along hillslopes as controlled by internal soil hydrology as opposed to overland flow. Many ecologists have found the "African" catena concept to be useful as an organizing principal for savanna studies, but there has been little recent research on catenas per se in Africa. Elsewhere however, there is a growing body of research that places the concept ever more strongly into a landscape evolution context. Here, we apply these new approaches to catenas in a South African savanna underlain by a heterogeneous suite of Basement granites straddling a gradient in effective precipitation. We constrain the weathering extent of hilly terrains formed on these oldrocks by calculating element losses with solid-phase mass-balance calculations augmented by cosmogenic (26Al/10Be) derived rates of landscape denudation. We test the efficacy of Ti, Zr and Nb as immobile elements to benchmark chemical losses and gains in these semi-arid weathering environments. We also trace and quantify the abundance of the host minerals for these elements (Ti = rutile and ilmenite, Nb = columbite and Zr = zircon and baddleyite) in a variety of rocks in the basement complex. This analysis provides the boundary conditions for assigning immobile elements to parent materials required for the mass balance calculations. We calculate total denudation using the cosmogenic isotopes and then partition it into chemical and physical loss vectors using the mass balance calculations for representative watersheds along the effective precipitation gradient. Preliminary results suggest that these semi-arid landscapes erode at a slow rate and the upper portions of the catenas are highly weathered with a predominance of quartz as existing primary minerals. The catenas appear to be some of the oldest and most highly evolved yet studied.

Mineralogy and geochemistry of a superhigh-organic-sulfur coal, Yanshan Coalfield, Yunnan, China: Evidence for a volcanic ash component and influence by submarine exhalation

USGS Publications Warehouse

Dai, S.; Ren, D.; Zhou, Y.; Chou, C.-L.; Wang, X.; Zhao, L.; Zhu, Xudong

2008-01-01

The mineralogy and geochemistry of a superhigh-organic-sulfur (SHOS) coal of Late Permian age from the Yanshan Coalfield, Yunnan Province, southwestern China, have been studied using optical microscope, low-temperature ashing plus X-ray diffraction analysis, scanning electron microscope equipped with energy-dispersive X-ray spectrometer, a sequential chemical extraction procedure, and inductively coupled plasma mass spectrometry. The M9 Coal from the Yanshan Coalfield is a SHOS coal that has a total sulfur content of 10.12%-11.30% and an organic sulfur content of 8.77%-10.30%. The minerals in the coal consist mainly of high-temperature quartz, sanidine, albite, muscovite, illite, pyrite, and trace amounts of kaolinite, plagioclase, akermanite, rutile, and dawsonite. As compared with ordinary worldwide (bituminous coals and anthracite) and Chinese coals, the M9 Coal is remarkably enriched in B (268????g/g), F (841????g/g), V (567????g/g), Cr (329????g/g), Ni (73.9????g/g), Mo (204????g/g), and U (153????g/g). In addition, elements including Se (25.2????g/g), Zr (262????g/g), Nb (20.1????g/g), Cd (2.07????g/g), and Tl (2.03????g/g) are also enriched in the coal. Occurrence of high-temperature quartz, sanidine, muscovite, and illite in the M9 Coal is evidence that there is a volcanic ash component in the coal that was derived from acid volcanic ashes fallen into the swamp during peat accumulation. Occurrence of albite and dawsonite in the coal and strong enrichment of some elements, including F, S, V, Cr, Ni, Mo and U, are attributed to the influence by submarine exhalation which invaded along with seawater into the anoxic peat swamp. Abundances of lithophile elements, including rare earth elements, Nb, Y, Zr, and TiO2, indicate that the silicate minerals in the coal were derived from the northern Vietnam Upland to the south of the basin. ?? 2008 Elsevier B.V. All rights reserved.

Atmospheric transport of trace elements and nutrients to the oceans

PubMed Central

Chance, R.

2016-01-01

This paper reviews atmospheric inputs of trace elements and nutrients to the oceans in the context of the GEOTRACES programme and provides new data from two Atlantic GEOTRACES cruises. We consider the deposition of nitrogen to the oceans, which is now dominated by anthropogenic emissions, the deposition of mineral dust and related trace elements, and the deposition of other trace elements which have a mixture of anthropogenic and dust sources. We then consider the solubility (as a surrogate for bioavailability) of the various elements. We consider briefly the sources, atmospheric transport and transformations of these elements and how this results in strong spatial deposition gradients. Solubility of the trace elements also varies systematically between elements, reflecting their sources and cycling, and for some trace elements there are also systematic gradients in solubility related to dust loading. Together, these effects create strong spatial gradients in the inputs of bioavailable trace elements to the oceans, and we are only just beginning to understand how these affect ocean biogeochemistry. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’. PMID:29035252

The role of plant-associated bacteria in the mobilization and phytoextraction of trace elements in contaminated soils

PubMed Central

Sessitsch, Angela; Kuffner, Melanie; Kidd, Petra; Vangronsveld, Jaco; Wenzel, Walter W.; Fallmann, Katharina; Puschenreiter, Markus

2013-01-01

Phytoextraction makes use of trace element-accumulating plants that concentrate the pollutants in their tissues. Pollutants can be then removed by harvesting plants. The success of phytoextraction depends on trace element availability to the roots and the ability of the plant to intercept, take up, and accumulate trace elements in shoots. Current phytoextraction practises either employ hyperaccumulators or fast-growing high biomass plants; the phytoextraction process may be enhanced by soil amendments that increase trace element availability in the soil. This review will focus on the role of plant-associated bacteria to enhance trace element availability in the rhizosphere. We report on the kind of bacteria typically found in association with trace element – tolerating or – accumulating plants and discuss how they can contribute to improve trace element uptake by plants and thus the efficiency and rate of phytoextraction. This enhanced trace element uptake can be attributed to a microbial modification of the absorptive properties of the roots such as increasing the root length and surface area and numbers of root hairs, or by increasing the plant availability of trace elements in the rhizosphere and the subsequent translocation to shoots via beneficial effects on plant growth, trace element complexation and alleviation of phytotoxicity. An analysis of data from literature shows that effects of bacterial inoculation on phytoextraction efficiency are currently inconsistent. Some key processes in plant–bacteria interactions and colonization by inoculated strains still need to be unravelled more in detail to allow full-scale application of bacteria assisted phytoremediation of trace element contaminated soils. PMID:23645938

The role of plant-associated bacteria in the mobilization and phytoextraction of trace elements in contaminated soils.

PubMed

Sessitsch, Angela; Kuffner, Melanie; Kidd, Petra; Vangronsveld, Jaco; Wenzel, Walter W; Fallmann, Katharina; Puschenreiter, Markus

2013-05-01

Phytoextraction makes use of trace element-accumulating plants that concentrate the pollutants in their tissues. Pollutants can be then removed by harvesting plants. The success of phytoextraction depends on trace element availability to the roots and the ability of the plant to intercept, take up, and accumulate trace elements in shoots. Current phytoextraction practises either employ hyperaccumulators or fast-growing high biomass plants; the phytoextraction process may be enhanced by soil amendments that increase trace element availability in the soil. This review will focus on the role of plant-associated bacteria to enhance trace element availability in the rhizosphere. We report on the kind of bacteria typically found in association with trace element - tolerating or - accumulating plants and discuss how they can contribute to improve trace element uptake by plants and thus the efficiency and rate of phytoextraction. This enhanced trace element uptake can be attributed to a microbial modification of the absorptive properties of the roots such as increasing the root length and surface area and numbers of root hairs, or by increasing the plant availability of trace elements in the rhizosphere and the subsequent translocation to shoots via beneficial effects on plant growth, trace element complexation and alleviation of phytotoxicity. An analysis of data from literature shows that effects of bacterial inoculation on phytoextraction efficiency are currently inconsistent. Some key processes in plant-bacteria interactions and colonization by inoculated strains still need to be unravelled more in detail to allow full-scale application of bacteria assisted phytoremediation of trace element contaminated soils.

The geology and geochemistry of Isla Floreana, Galápagos: A different type of late-stage ocean island volcanism: Chapter 6 in The Galápagos: A natural laboratory for the earth sciences

USGS Publications Warehouse

Harpp, Karen S.; Geist, Dennis J.; Koleszar, Alison M.; Christensen, Branden; Lyons, John; Sabga, Melissa; Rollins, Nathan; Harpp, Karen S.; Mittelstaedt, Eric; d'Ozouville, Noémi; Graham, David W

2014-01-01

Isla Floreana, the southernmost volcano in the Galápagos Archipelago, has erupted a diverse suite of alkaline basalts continually since 1.5 Ma. Because these basalts have different compositions than xenoliths and older lavas from the deep submarine sector of the volcano, Floreana is interpreted as being in a rejuvenescent or late-stage phase of volcanism. Most lavas contain xenoliths, or their disaggregated remains. The xenolithic debris and large ranges in composition, including during single eruptions, indicate that the magmas do not reside in crustal magma chambers, unlike magmas in the western Galápagos. Floreana lavas have distinctive trace element compositions that are rich in fluid-immobile elements (e.g., Ta, Nb, Th, Zr) and even richer in fluid-mobile elements (e.g., Ba, Sr, Pb). Rare earth element (REE) patterns are light REE-enriched and distinctively concave-up. Neodymium isotopic ratios are comparable to those from Fernandina, at the core of the Galápagos plume, but Floreana has the most radiogenic Sr and Pb isotopic ratios in the archipelago. These trace element patterns and isotopic ratios are attributed to a mixed source originating within the Galápagos plume, which includes depleted upper mantle, plume material rich in TITAN elements (Ti, Ta, Nb), and recycled oceanic crust that has undergone partial dehydration in an ancient subduction zone. Because Floreana lies at the periphery of the Galápagos plume, melting occurs mostly in the spinel zone, and enriched components dominate; the Floreana recycled mantle component influence is detectable in volcanoes along the entire southern periphery of the archipelago as well. Floreana is the only Galápagos volcano known to have undergone late-stage volcanism. Here, however, the secondary stage activity is more compositionally enriched than the shield-building phase, in contrast to what is observed in Hawai‘i, suggesting that the mechanism driving late-stage volcanism may vary among ocean island provinces.

Geochemical, oxygen, and neodymium isotope compositions of metasediments from the Abitibi greenstone belt and Pontiac Subprovince, Canada: Evidence for ancient crust and Archean terrane juxtaposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, R.; Kerrich, R.; Maas, R.

1993-02-01

The Abitibi greenstone belt (AGB) and Pontiac Subprovince (PS) in the southwestern Superior Province are adjacent greenstone-plutonic and metasedimentary-dominated terranes, respectively, separated by a major fault zone. Metasediments from these two contrasting terranes are compared in terms of major- and trace-element and O- and Nd-isotope compositions, and detrital zircon ages. The following two compositional populations of metasediments are present in the low-grade, Abitibi southern volcanic zone: (1) a mafic-element-enriched population (MEP) characterized by flat, depleted REE patterns; enhanced Mg, Cr, Co, Ni, and Sc; low-incompatible-element contents; and minor or absent normalized negative troughs at Nb, Ta, and Ti; and (2)more » a low-mafic-element population (LMEP) featuring LREE-enriched patterns; enhanced Rb, Cs, Ba, Th, and U contents; and pronounced normalized negative troughs at Nb, Ta, and Ti. These geochemical features are interpreted to indicate that the MEP sediments were derived from an ultramafic- and mafic-dominated oceanic provenance, whereas the LMEP sediments represent mixtures of mafic and felsic are source rocks. The PS metasediments are essentially indistinguishable from Abitibi LMEP on the basis of major-element and transition metal abundances, suggesting comparable types of source rocks and degrees of maturity, but are distinct in terms of some trace elements and O-isotope compositions. The Pontiac metasediments are depleted in [sup 18]O and enriched in Cs, Ba, Pb, Th, U, Nb, Ta, Hf, Zr, and total REE and also have higher ratios of Rb/K, Cs/Rb, Ba/Rb, Ta/Nb, Th/La, and Ba/La relative to the Abitibi LMEP. Two subtypes of REE patterns have been identified in PS metasediments. The first subtype is interpreted to be derived from provenances of mixed mafic and felsic volcanic rocks, whereas the Eu-depleted type has features that are typical of post-Archean sediments or Archean K-rich granites and volcanic equivalents. 100 refs., 9 figs., 4 tabs.« less

In-situ trace element and Sr isotopic compositions of mantle xenoliths constrain two-stage metasomatism beneath the northern North China Craton

NASA Astrophysics Data System (ADS)

Wu, Dan; Liu, Yongsheng; Chen, Chunfei; Xu, Rong; Ducea, Mihai N.; Hu, Zhaochu; Zong, Keqing

2017-09-01

Subduction and collision are the key processes triggering geochemical refertilization of the lithospheric mantle beneath cratons. However, the way that the subducted plate influences the cratonic lithospheric mantle remains unclear. Here, in-situ major and trace-element and Sr isotopic compositions of peridotite and pyroxenite xenoliths carried by the Dongbahao Cenozoic basalts, located close to the northern margin of North China Craton (NCC), were examined to investigate the effects of the subducted Paleo-Asian oceanic plate on the lithospheric mantle of the NCC. Based on petrographic and geochemical features, peridotites were subdivided into two types recording two-stage metasomatism. Clinopyroxene (Cpx) in both types of peridotites show chemical zoning. In those peridotites we refer to as Type 1 peridotites, Cpx exhibit uniform convex-upward rare earth element (REE) patterns but core-rim variations in 87Sr/86Sr ratios (0.7065-0.7082 in the cores and 0.7043-0.7059 in the spongy rims), and have high (La/Yb)N ratios (> 1.12) (N means normalized to chondrite), relatively low Ti/Eu ratios (< 3756) and negative high field strength element (HFSE) (Nb, Ta, Zr, Hf and Ti) anomalies in the cores, indicating early-stage metasomatism by carbonatitic melts derived from the subducted sedimentary carbonate rocks. Cpx in the Type 2 peridotites have highly variable REE patterns (from light rare earth element (LREE)-depleted to LREE-enriched) and feature zoned Sr isotopic compositions contrasting to those in Type 1, i.e., increasing 87Sr/86Sr ratios from the cores (0.7020-0.7031) to the spongy rims (0.7035-0.7041). Accompanying variations of 87Sr/86Sr ratios, Cpx in both types of peridotites display increasing Nb/La ratios from the cores to the spongy rims. In addition, Cpx in the Type 2 peridotites show remarkably increased (La/Yb)N, Ca/Al, Sm/Hf and Zr/Hf ratios but decreased Ti/Eu and Ti/Nb ratios from the cores to the spongy rims. These features imply a later-stage metasomatism by CO2-rich silicate melts derived from carbonated eclogites. Pyroxenites were also classified into two types. Both types of pyroxenites show higher Ni content in Cpx and orthopyroxene than peridotites at the same Mg# (= 100 ∗ Mg/(Mg + Fe), atomic number) level. Their Cpx show high Ti/Eu, Ti/Sr ratios and similar 87Sr/86Sr ratios (0.7039-0.7055) to the Cpx spongy rims in peridotites, suggesting that pyroxenites originated from silicate melt-peridotite reactions in the later-stage metasomatism. These observations collectively indicate that the lithospheric mantle beneath the northern NCC presents evidence for two distinct mantle metasomatic events. We propose that both were caused by the subduction of the Paleo-Asian oceanic plate, which could have contributed significantly to the transformation of the lithospheric mantle beneath the northern NCC.

Spatial variability of trace elements and sources for improved exposure assessment in Barcelona

NASA Astrophysics Data System (ADS)

Minguillón, María Cruz; Cirach, Marta; Hoek, Gerard; Brunekreef, Bert; Tsai, Ming; de Hoogh, Kees; Jedynska, Aleksandra; Kooter, Ingeborg M.; Nieuwenhuijsen, Mark; Querol, Xavier

2014-06-01

Trace and major elements concentrations in PM10 and PM2.5 were measured at 20 sites spread in the Barcelona metropolitan area (1 rural background, 6 urban background, 13 road traffic sites) and at 1 reference site. Three 2-week samples per site and size fraction were collected during 2009 using low volume samplers, adding a total of 120 samples. Collected samples were analysed for elemental composition using Energy Dispersive X-ray fluorescence (XRF). EC, OC, and hopanes and steranes concentrations in PM2.5 were determined. Positive Matrix Factorisation (PMF) model was used for a source apportionment analysis. The work was performed as part of the ESCAPE project. Elements were found in concentrations within the usual range in Spanish urban areas. Mineral elements were measured in higher concentrations during the warm season, due to enhanced resuspension; concentrations of fueloil combustion elements were also higher in summer. Elements in higher concentration at the traffic sites were: Ba, Cr, Cu, Fe, Mn, Mo, Pb, Sn, Zn and Zr. Spatial variations related to non-traffic sources were observed for concentrations of Br, Cl, K, and Na (sea salt origin) and Ni, V and S (shipping emissions), which were higher at the coastal sites, as well as for Zn and Pb, higher at sites closer to industrial facilities. Five common sources for PM10 and PM2.5 were identified by PMF: road traffic (with tracers Ba, Cr, Cu, Fe, Mo and Zn); fueloil combustion (Ni and V); secondary sulphate; industry (Pb and Zn); and mineral source (Al, Ca, Mg, Si, Sr and Ti). A marine aerosol source, a mixture of sea salt with aged anthropogenic aerosols, was found only in PM10. EC, hopanes and steranes concentrations correlate strongly with the PM10 road traffic source contributions, being hence all attributed to the same source. OC may arise from other sources in addition to road traffic and have a high contribution of secondary OC. Significant spatial and temporal variation in the PM2.5 and PM10 elemental composition was found. Spatial patterns differed per element, related to the main source. The identified source contributions can be used in health studies of source-specific particles.

Multi-element study of sediments from the river Khai River - Nha Trang Bay estuarine system, South China Sea.

NASA Astrophysics Data System (ADS)

Koukina, Sofia; Lobus, Nikolai; Peresypkin, Valery; Baturin, Gleb; Smurov, Andrey

2013-04-01

Major (Al, Fe, Ti, Mg, Ca, Na, K), minor (Mn) and trace (Cr, Ni, Cd, V, Zn, Cu, Pb, Sb, Bi, Sn, Ag, Li, Co, As, Zr, Mo, Hg) elements along with nutrients (TOC, TS, TP) and TIC were first determined in ten surface sediment samples from the Khai River - Nha Trang Bay estuarine system, South China Sea. According to the sediment quality guidelines and reference background values, most of the element contents that were studied were below the threshold levels, while the content of Ag exceeded significantly the hazardous levels in the most of the samples along the river - sea transect. The local anthropogenic and/or environmental sources of Ag within the region need special study. Aluminum and lithium normalization indicated some specific features in the abundance and distribution of the elements along the salinity gradient. The mean grain size of the sediments decreased from the river part to the bay part of the transect. Sedimentary TOC was relatively low (1-2 %) and showed independent distribution along the river - sea transect in relation to the other elements that were studied. Ca, Ba and Sr distribution showed some sporadic enrichment and were largely controlled by the TIC content in sediments. Sedimentary TP, Al, Fe, Mn, Ti, Na, K, Li, Co, Cs, Zn and V varied within the narrow range and tended to increase seaward. These elements are most likely controlled by the accumulation of their fine grained aluminosilicate host minerals and materials at sites determined by hydrodynamic conditions, i. e., in the sea floor depression. TS, As, Sn, Bi, U, Cd and Mo were relatively low in the sediments studied and tended to decrease seaward with the slight elevation in the intermediate part of the transect. These elements can be scavenged by and/or co-precipitated with the dissolved and particulate materials of the river discharge and further deposited on the river - sea geochemical barrier in the course of estuarine sedimentation. The distribution of Ni, Cr, Zr Cu, Pb, Sb, Hg and, especially, Ag was characterized by anomalous high concentrations in the intermediate part of the river - sea transect at sites located in the harbor zone. This might be due to the point anthropogenic pollution from local human activities, i.e., fishing, shipping, fueling, waste and sewage sludge outflow, and, especially, from the construction of new touristic facilities in the Nha Trang Bay. Overall, the abundance and distribution of the environmental/anthropogenic elements are controlled by various estuarine biogeochemical processes characteristic for the marginal filter of the estuarine water mixing zone.

Magma Differentiation Processes That Develop an "Enriched" Signature in the Izu Bonin Rear Arc: Evidence from Drilling at IODP Site U1437

NASA Astrophysics Data System (ADS)

Heywood, L. J.; DeBari, S. M.; Schindlbeck, J. C.; Escobar-Burciaga, R. D.

2015-12-01

The Izu Bonin rear arc represents a unique laboratory to study the development of continental crust precursors at an intraoceanic subduction zone., Volcanic output in the Izu Bonin rear arc is compositionally distinct from the Izu Bonin main volcanic front, with med- to high-K and LREE-enrichment similar to the average composition of the continental crust. Drilling at IODP Expedition 350 Site U1437 in the Izu Bonin rear arc obtained volcaniclastic material that was deposited from at least 13.5 Ma to present. IODP Expedition 350 represents the first drilling mission in the Izu Bonin rear arc region. This study presents fresh glass and mineral compositions (obtained via EMP and LA-ICP-MS) from unaltered tephra layers in mud/mudstone (Lithostratigraphic Unit I) and lapillistone (Lithostratigraphic Unit II) <4.5 Ma to examine the geochemical signature of Izu Bonin rear arc magmas. Unit II samples are coarse-grained tephras that are mainly rhyolitic in composition (72.1-77.5 wt. % SiO2, 3.2-3.9 wt. % K2O and average Mg# 24) and LREE-enriched. These rear-arc rhyolites have an average La/Sm of 2.6 with flat HREEs, average Th/La of 0.15, and Zr/Y of 4.86. Rear-arc rhyolite trace element signature is distinct from felsic eruptive products from the Izu Bonin main volcanic front, which have lower La/Sm and Th/La as well as significantly lower incompatible element concentrations. Rear arc rhyolites have similar trace element ratios to rhyolites from the adjacent but younger backarc knolls and actively-extending rift regions, but the latter is typified by lower K2O, as well as a smaller degree of enrichment in incompatible elements. Given these unique characteristics, we explore models for felsic magma formation and intracrustal differentiation in the Izu Bonin rear arc.

Doped ZrO2 for future lead free piezoelectric devices

NASA Astrophysics Data System (ADS)

Starschich, S.; Böttger, U.

2018-01-01

The ferroelectric and piezoelectric properties of doped ZrO2 prepared by chemical solution deposition (CSD) are investigated. Doping with different elements such as Mg, In, La, and Y leads to a stabilization of the constricted hysteresis. As shown in a previous work, for the constricted hysteresis of ZrO2, the piezoelectric response is significantly larger compared to ZrO2 with a normal hysteresis. The Mg doped ZrO2 shows a strong temperature and cycle stability. For the piezoelectric properties, a magnesium concentration of 7% shows the largest piezoelectric response with a piezoelectric coefficient of >10 pm/V, as well as the best cycle stability. Due to thicker films, which can be realized by the CSD technique, the shown doped ZrO2 films are a promising candidate for energy related applications such as piezoelectric energy harvesting as well as for microelectromechanical systems.

Parametric Study of Amorphous High-Entropy Alloys formation from two New Perspectives: Atomic Radius Modification and Crystalline Structure of Alloying Elements

NASA Astrophysics Data System (ADS)

Hu, Q.; Guo, S.; Wang, J. M.; Yan, Y. H.; Chen, S. S.; Lu, D. P.; Liu, K. M.; Zou, J. Z.; Zeng, X. R.

2017-01-01

Chemical and topological parameters have been widely used for predicting the phase selection in high-entropy alloys (HEAs). Nevertheless, previous studies could be faulted due to the small number of available data points, the negligence of kinetic effects, and the insensitivity to small compositional changes. Here in this work, 92 TiZrHfM, TiZrHfMM, TiZrHfMMM (M = Fe, Cr, V, Nb, Al, Ag, Cu, Ni) HEAs were prepared by melt spinning, to build a reliable and sufficiently large material database to inspect the robustness of previously established parameters. Modification of atomic radii by considering the change of local electronic environment in alloys, was critically found out to be superior in distinguishing the formation of amorphous and crystalline alloys, when compared to using atomic radii of pure elements in topological parameters. Moreover, crystal structures of alloying element were found to play an important role in the amorphous phase formation, which was then attributed to how alloying hexagonal-close-packed elements and face-centered-cubic or body-centered-cubic elements can affect the mixing enthalpy. Findings from this work not only provide parametric studies for HEAs with new and important perspectives, but also reveal possibly a hidden connection among some important concepts in various fields.

Dielectric studies of (x) NiFe2O4 + (1 - x) BaTi0.9Zr0.1O3 (where x = 0, 0.25, 0.50, 0.75 and 1)

NASA Astrophysics Data System (ADS)

Wadhwani, Kiran; Srivastava, Subodh; Mathur, Shubhra

2018-05-01

We present the room temperature dielectric studies of the samples in the series (x) NiFe2O4 + (1-x) BaTi0.9Zr0.1O3 (where x = 0, 0.25, 0.50, 0.75 and 1) containing nickel ferrite and Zr substituted barium titanate as the ferroelectric phase and their magnetoelectric (ME) composites in mixed in different molar ratios. Solid state diffusion has been used for the synthesis of samples. Powder X-ray diffraction (XRD) confirms the formation of ferrite and ferroelectric phases and their presence in all three composites with no impurity traces. Room temperature dielectric measurements have been made as a function of frequency (ranging from 100 Hz to 1 MHz).

Trace Elements and Carbon and Nitrogen Stable Isotopes in Organisms from a Tropical Coastal Lagoon

PubMed Central

van Hattum, B.; de Boer, J.; van Bodegom, P. M.; Rezende, C. E.; Salomons, W.

2010-01-01

Trace elements (Fe, Mn, Al, Zn, Cr, Cu, Ni, Pb, Cd, Hg, and As) and stable isotope ratios (δ13C and δ15N) were analyzed in sediments, invertebrates, and fishes from a tropical coastal lagoon influenced by iron ore mining and processing activities to assess the differences in trace element accumulation patterns among species and to investigate relations with trophic levels of the organisms involved. Overall significant negative relations between trophic level (given by 15N) and trace element concentrations in gastropods and crustaceans showed differences in internal controls of trace element accumulation among the species of different trophic positions, leading to trace element dilution. Generally, no significant relation between δ15N and trace element concentrations was observed among fish species, probably due to omnivory in a number of species as well as fast growth. Trace element accumulation was observed in the fish tissues, with higher levels of most trace elements found in liver compared with muscle and gill. Levels of Fe, Mn, Al, and Hg in invertebrates, and Fe and Cu in fish livers, were comparable with levels in organisms and tissues from other contaminated areas. Trace element levels in fish muscle were below the international safety baseline standards for human consumption. PMID:20217062

Trace elements and carbon and nitrogen stable isotopes in organisms from a tropical coastal lagoon.

PubMed

Pereira, A A; van Hattum, B; de Boer, J; van Bodegom, P M; Rezende, C E; Salomons, W

2010-10-01

Trace elements (Fe, Mn, Al, Zn, Cr, Cu, Ni, Pb, Cd, Hg, and As) and stable isotope ratios (delta(13)C and delta(15)N) were analyzed in sediments, invertebrates, and fishes from a tropical coastal lagoon influenced by iron ore mining and processing activities to assess the differences in trace element accumulation patterns among species and to investigate relations with trophic levels of the organisms involved. Overall significant negative relations between trophic level (given by (15)N) and trace element concentrations in gastropods and crustaceans showed differences in internal controls of trace element accumulation among the species of different trophic positions, leading to trace element dilution. Generally, no significant relation between delta(15)N and trace element concentrations was observed among fish species, probably due to omnivory in a number of species as well as fast growth. Trace element accumulation was observed in the fish tissues, with higher levels of most trace elements found in liver compared with muscle and gill. Levels of Fe, Mn, Al, and Hg in invertebrates, and Fe and Cu in fish livers, were comparable with levels in organisms and tissues from other contaminated areas. Trace element levels in fish muscle were below the international safety baseline standards for human consumption.

Optical and structural characterization of Ge clusters embedded in ZrO2

NASA Astrophysics Data System (ADS)

Agocs, E.; Zolnai, Z.; Rossall, A. K.; van den Berg, J. A.; Fodor, B.; Lehninger, D.; Khomenkova, L.; Ponomaryov, S.; Gudymenko, O.; Yukhymchuk, V.; Kalas, B.; Heitmann, J.; Petrik, P.

2017-11-01

The change of optical and structural properties of Ge nanoclusters in ZrO2 matrix have been investigated by spectroscopic ellipsometry versus annealing temperatures. Radio-frequency top-down magnetron sputtering approach was used to produce the samples of different types, i.e. single-layers of pure Ge, pure ZrO2 and Ge-rich-ZrO2 as well as multi-layers stacked of 40 periods of 5-nm-Ge-rich-ZrO2 layers alternated by 5-nm-ZrO2 ones. Germanium nanoclusters in ZrO2 host were formed by rapid-thermal annealing at 600-800 °C during 30 s in nitrogen atmosphere. Reference optical properties for pure ZrO2 and pure Ge have been extracted using single-layer samples. As-deposited multi-layer structures can be perfectly modeled using the effective medium theory. However, annealed multi-layers demonstrated a significant diffusion of elements that was confirmed by medium energy ion scattering measurements. This fact prevents fitting of such annealed structure either by homogeneous or by periodic multi-layer models.

Effect of atomic size on undercoolability of binary solid solution alloy liquids with Zr, Ti, and Hf using electrostatic levitation

NASA Astrophysics Data System (ADS)

Jeon, S.; Kang, D.-H.; Lee, Y. H.; Lee, S.; Lee, G. W.

2016-11-01

We investigate the relationship between the excess volume and undercoolability of Zr-Ti and Zr-Hf alloy liquids by using electrostatic levitation. Unlike in the case of Zr-Hf alloy liquids in which sizes of the constituent atoms are matched, a remarkable increase of undercoolability and negative excess volumes are observed in Zr-Ti alloy liquids as a function of their compositional ratios. In this work, size mismatch entropies for the liquids were obtained by calculating their hard sphere diameters, number densities, and packing fractions. We also show that the size mismatch entropy, which arises from the differences in atomic sizes of the constituent elements, plays an important role in determining the stabilities of metallic liquids.

Surface-water-quality assessment of the Yakima River basin in Washington; spatial and temporal distribution of trace elements in water, sediment, and aquatic biota, 1987-91; with a section on geology

USGS Publications Warehouse

Fuhrer, Gregory J.; Cain, Daniel J.; McKenzie, Stuart W.; Rinella, Joseph F.; Crawford, J. Kent; Skach, Kenneth A.; Hornberger, Michelle I.; Gannett, Marshall W.

1999-01-01

The report describes the distribution of trace elements in sediment, water, and aquatic biota in the Yakima River basin, Washington. Trace elements were determined from streambed sediment, suspended sediment, filtered and unfiltered water samples, aquatic insects, clams, fish livers, and fish fillets between 1987 and 1991. The distribution of trace elements in these media was related to local geology and anthropogenic sources. Additionally, annual and instantaneous loads were estimated for trace elements associated with suspended sediment and trace elements in filtered water samples. Trace elements also were screened against U.S. Environmental Protection Agency guidelines established for the protection of human health and aquatic life.

A new perspective of using sequential extraction: To predict the deficiency of trace elements during anaerobic digestion.

PubMed

Cai, Yafan; Wang, Jungang; Zhao, Yubin; Zhao, Xiaoling; Zheng, Zehui; Wen, Boting; Cui, Zongjun; Wang, Xiaofen

2018-09-01

Trace elements were commonly used as additives to facilitate anaerobic digestion. However, their addition is often blind because of the complexity of reaction conditions, which has impeded their widespread application. Therefore, this study was conducted to evaluate deficiencies in trace elements during anaerobic digestion by establishing relationships between changes in trace element bioavailability (the degree to which elements are available for interaction with biological systems) and digestion performance. To accomplish this, two batch experiments were conducted. In the first, sequential extraction was used to detect changes in trace element fractions and then to evaluate trace element bioavailability in the whole digestion cycle. In the second batch experiment, trace elements (Co, Fe, Cu, Zn, Mn, Mo and Se) were added to the reaction system at three concentrations (low, medium and high) and their effects were monitored. The results showed that sequential extraction was a suitable method for assessment of the bioavailability of trace elements (appropriate coefficient of variation and recovery rate). The results revealed that Se had the highest (44.2%-70.9%) bioavailability, while Fe had the lowest (1.7%-3.0%). A lack of trace elements was not directly related to their absolute bioavailability, but was instead associated with changes in their bioavailability throughout the digestion cycle. Trace elements were insufficient when their bioavailability was steady or increased over the digestion cycle. These results indicate that changes in trace element bioavailability during the digestion cycle can be used to predict their deficiency. Copyright © 2018 Elsevier Ltd. All rights reserved.

Chemistry of the subalkalic silicic obsidians

USGS Publications Warehouse

MacDonald, Ray; Smith, Robert L.; Thomas, John E.

1992-01-01

Nonhydrated obsidians are quenched magmatic liquids that record in their chemical compositions details of the tectonic environment of formation and of the differentiation mechanisms that affected their subsequent evolution. This study attempts to analyze, in terms of geologic processes, the compositional variations in the subalkalic silicic obsidians (Si02≥70 percent by weight, molecular (Na2O+K20)>Al2O3). New major- and trace-element determinations of 241 samples and a compilation of 130 published major-element analyses are reported and interpreted. Obsidians from five different tectonic settings are recognized: (1) primitive island arcs, (2) mature island arcs, (3) continental margins, (4) continental interiors, and (5) oceanic extensional zones. Tectonomagmatic discrimination between these groups is successfully made on Nb-Ta, Nb-FeOt and Th-Hf-Ta plots, and compositional ranges and averages for each group are presented. The chemical differences between groups are related to the type of crust in which magmas were generated. With increasingly sialic (continental type) crust, the obsidians show overall enrichment in F, Be, Li, Mo, Nb, Rb, Sn, Ta, U, W, Zn, and the rare-earth elements, and depletion in Mg, Ca, Ba, Co, Sc, Sr, and Zr. They become more potassic, have higher Fe/Mg and F/Cl ratios, and lower Zr/Hf, Nb/Ta, and Th/U ratios. Higher values of total rare-earth elements are accompanied by light rare-earth-element enrichment and pronounced negative Eu anomalies. An attempt is made to link obsidian chemistry to genetic mechanlism. Two broad groups of rocks are distinguished: one generated where crystal-liquid processes dominated (CLPD types), which are the products of crustal anatexis, possibly under conditions of low halogen fugacity, ± crystal fractionation ± magma mixing; and a second group represented by rocks formed in the upper parts of large magma chambers by interplays of crystal fractionation, volatile transfer, magma mixing, and possibly various liquid-state differentiation mechanisms, or in other words a complex interaction of petrogenetic processes (CIPP types). Such rocks may also form by volatile-fluxed partial melting of the wallrocks, and subsequent mixing into the magma reservoir. Compositional ranges and averages for CLPD and CIPP obsidians are given. It is shown by analogy with well-documented, zoned ash-flow ruffs that obsidians fractionated by CIPP have very low Mg, P, Ba, and Sr contents, flat rare-earth-element patterns with extensive Eu anomalies, low K/Rb and Zr/Nb ratios, and relatively high Na2O/K2O ratios. There is, however, considerable compositional overlap between CLPD and CIPP obsidians. The effects of magma mixing, assimilation, and vapor-phase transport in producing compositional variations in the obsidians are briefly assessed. The geochemistry of the subalkalic silicic obsidians is described on an element-by-element basis, in order to provide a database for silicic magma compositions that will hopefully contribute to studies of granitic rocks. Attempts are also made to isolate the geochemical effects of tectonic environment and genetic mechanism for each element, by comparison with data from crystal-liquid equilibria-controlled systems, from ash-flow sheets zoned by CIPP, and from mixed-magma series. A final tabulation relates the complexities of obsidian geochemistry to all the tectonic and genetic variables.

Trace element distribution in peridotite xenoliths from Tok, SE Siberian craton: A record of pervasive, multi-stage metasomatism in shallow refractory mantle

NASA Astrophysics Data System (ADS)

Ionov, Dmitri A.; Chazot, Gilles; Chauvel, Catherine; Merlet, Claude; Bodinier, Jean-Louis

2006-03-01

Spinel peridotite xenoliths in alkali basalts at Tok, SE Siberian craton range from fertile lherzolites to harzburgites and wehrlites; olivine-rich (70-84%) rocks are dominant. REE patterns in the lherzolites range from nearly flat for fertile rocks (14-17% cpx) to LREE-enriched; the enrichments are positively correlated with modal olivine, consistent with high-permeability of olivine-rich rocks during melt percolation. Clinopyroxene in olivine-rich Tok peridotites typically has convex-upward trace element patterns (La/Nd PM < 1 and Nd/Yb PM ≫ 1), which we consider as evidence for equilibration with evolved silicate liquids (with higher REE and lower Ti contents than in host basalts). Whole-rock patterns of the olivine-rich xenoliths range from convex-upward to LREE-enriched (La/Nd PM > 1); the LREE-enrichments are positively correlated with phosphorus abundances and are mainly hosted by accessory phosphates and P-rich cryptocrystalline materials. In addition to apatite, some Tok xenoliths contain whitlockite (an anhydrous, halogen-poor and Na-Mg-rich phosphate), which is common in meteorites and lunar rocks, but has not been reported from any terrestrial mantle samples. Some olivine-rich peridotites have generations of clinopyroxene with distinct abundances of Na, LREE, Sr and Zr. The mineralogical and trace element data indicate that the lithospheric mantle section represented by the xenoliths experienced a large-scale metasomatic event produced by upward migration of mafic silicate melts followed by percolation of low- T, alkali-rich melts and fluids. Chromatographic fractionation and fractional crystallisation of the melts close to the percolation front produced strong LREE-enrichments, which are most common in the uppermost mantle and are related to carbonate- and P 2O 5-rich derivatives of the initial melt. Reversal and gradual retreat of the percolation front during thermal relaxation to ambient geotherm ("retrograde" metasomatism) caused local migration and entrapment of small-volume residual fluids and precipitation of volatile-rich accessory minerals. A distinct metasomatic episode, which mainly produced "anhydrous" late-stage interstitial materials was concomitant with the alkali basaltic magmatism, which brought the xenoliths to the surface.

Trace element profiles of the sea anemone Anemonia viridis living nearby a natural CO2 vent

PubMed Central

Borell, Esther M.; Fine, Maoz; Shaked, Yeala

2014-01-01

Ocean acidification (OA) is not an isolated threat, but acts in concert with other impacts on ecosystems and species. Coastal marine invertebrates will have to face the synergistic interactions of OA with other global and local stressors. One local factor, common in coastal environments, is trace element contamination. CO2 vent sites are extensively studied in the context of OA and are often considered analogous to the oceans in the next few decades. The CO2 vent found at Levante Bay (Vulcano, NE Sicily, Italy) also releases high concentrations of trace elements to its surrounding seawater, and is therefore a unique site to examine the effects of long-term exposure of nearby organisms to high pCO2 and trace element enrichment in situ. The sea anemone Anemonia viridis is prevalent next to the Vulcano vent and does not show signs of trace element poisoning/stress. The aim of our study was to compare A. viridis trace element profiles and compartmentalization between high pCO2 and control environments. Rather than examining whole anemone tissue, we analyzed two different body compartments—the pedal disc and the tentacles, and also examined the distribution of trace elements in the tentacles between the animal and the symbiotic algae. We found dramatic changes in trace element tissue concentrations between the high pCO2/high trace element and control sites, with strong accumulation of iron, lead, copper and cobalt, but decreased concentrations of cadmium, zinc and arsenic proximate to the vent. The pedal disc contained substantially more trace elements than the anemone’s tentacles, suggesting the pedal disc may serve as a detoxification/storage site for excess trace elements. Within the tentacles, the various trace elements displayed different partitioning patterns between animal tissue and algal symbionts. At both sites iron was found primarily in the algae, whereas cadmium, zinc and arsenic were primarily found in the animal tissue. Our data suggests that A. viridis regulates its internal trace element concentrations by compartmentalization and excretion and that these features contribute to its resilience and potential success at the trace element-rich high pCO2 vent. PMID:25250210

Apatite layer growth on glassy Zr48Cu36Al8Ag8 sputtered titanium for potential biomedical applications

NASA Astrophysics Data System (ADS)

Thanka Rajan, S.; Karthika, M.; Bendavid, Avi; Subramanian, B.

2016-04-01

The bioactivity of magnetron sputtered thin film metallic glasses (TFMGs) of Zr48Cu36Al8Ag8 (at.%) on titanium substrates was tested for bio implant applications. The structural and elemental compositions of TFMGs were analyzed by XRD, XPS and EDAX. X-ray diffraction analysis displayed a broad hump around the incident angle of 30-50°, suggesting that the coatings possess a glassy structure. An in situ crystal growth of hydroxyapatite was observed by soaking the sputtered specimen in simulated body fluid (SBF). The nucleation and growth of a calcium phosphate (Ca-P) bone-like hydroxyapatite on Zr48Cu36Al8Ag8 (at.%) TFMG from SBF was investigated by using XRD, AFM and SEM. The presence of calcium and phosphorus elements was confirmed by EDAX and XPS. In vitro electrochemical corrosion studies indicated that the Zr-based TFMG coating sustain in the stimulated body-fluid (SBF), exhibiting superior corrosion resistance with a lower corrosion penetration rate and electrochemical stability than the bare crystalline titanium substrate.

Quantification of colloidal and aqueous element transfer in soils: The dual-phase mass balance model

USGS Publications Warehouse

Bern, Carleton R.; Thompson, Aaron; Chadwick, Oliver A.

2015-01-01

Mass balance models have become standard tools for characterizing element gains and losses and volumetric change during weathering and soil development. However, they rely on the assumption of complete immobility for an index element such as Ti or Zr. Here we describe a dual-phase mass balance model that eliminates the need for an assumption of immobility and in the process quantifies the contribution of aqueous versus colloidal element transfer. In the model, the high field strength elements Ti and Zr are assumed to be mobile only as suspended solids (colloids) and can therefore be used to distinguish elemental redistribution via colloids from redistribution via dissolved aqueous solutes. Calculations are based upon element concentrations in soil, parent material, and colloids dispersed from soil in the laboratory. We illustrate the utility of this model using a catena in South Africa. Traditional mass balance models systematically distort elemental gains and losses and changes in soil volume in this catena due to significant redistribution of Zr-bearing colloids. Applying the dual-phase model accounts for this colloidal redistribution and we find that the process accounts for a substantial portion of the major element (e.g., Al, Fe and Si) loss from eluvial soil. In addition, we find that in illuvial soils along this catena, gains of colloidal material significantly offset aqueous elemental loss. In other settings, processes such as accumulation of exogenous dust can mimic the geochemical effects of colloid redistribution and we suggest strategies for distinguishing between the two. The movement of clays and colloidal material is a major process in weathering and pedogenesis; the mass balance model presented here is a tool for quantifying effects of that process over time scales of soil development.

Trace elements as quantitative probes of differentiation processes in planetary interiors

NASA Technical Reports Server (NTRS)

Drake, M. J.

1980-01-01

The characteristic trace element signature that each mineral in the source region imparts on the magma constitutes the conceptual basis for trace element modeling. It is shown that abundances of trace elements in extrusive igneous rocks may be used as petrological and geochemical probes of the source regions of the rocks if differentiation processes, partition coefficients, phase equilibria, and initial concentrations in the source region are known. Although compatible and incompatible trace elements are useful in modeling, the present review focuses primarily on examples involving the rare-earth elements.

Parenteral trace element provision: recent clinical research and practical conclusions

PubMed Central

Stehle, P; Stoffel-Wagner, B; Kuhn, K S

2016-01-01

The aim of this systematic review (PubMed, www.ncbi.nlm.nih.gov/pubmed and Cochrane, www.cochrane.org; last entry 31 December 2014) was to present data from recent clinical studies investigating parenteral trace element provision in adult patients and to draw conclusions for clinical practice. Important physiological functions in human metabolism are known for nine trace elements: selenium, zinc, copper, manganese, chromium, iron, molybdenum, iodine and fluoride. Lack of, or an insufficient supply of, these trace elements in nutrition therapy over a prolonged period is associated with trace element deprivation, which may lead to a deterioration of existing clinical symptoms and/or the development of characteristic malnutrition syndromes. Therefore, all parenteral nutrition prescriptions should include a daily dose of trace elements. To avoid trace element deprivation or imbalances, physiological doses are recommended. PMID:27049031

Trace Elements Characteristic Based on ICP-AES and the Correlation of Flavonoids from Sparganii rhizoma.

PubMed

Wang, Xinsheng; Wu, Yanfang; Wu, Chengying; Wu, Qinan; Niu, Qingshan

2018-04-01

The aim of the present work was to investigate the trace elements and the correlation with flavonoids from Sparganii rhizoma. The ICP-AES and ultraviolet-visible spectroscopy were employed to analyze trace elements and flavonoids. The concentrations of trace elements and flavonoids were calculated using standard curve. The content of flavonoids was expressed as rutin equivalents. The cluster analysis was applied to evaluate geographical features of S. rhizoma from different geographical regions. The correlation analysis was used to obtain the relationship between the trace elements and flavonoids. The results indicated that the 15 trace elements were measured and the K, Ca, Mg, Na, Mn, Al, Cu, and Zn are rich in Sparganii rhizome. The different producing regions samples were classified into four groups. There was a weak relationship between trace elements and flavonoids.

Petrologic and chemical changes in ductile shear zones as a function of depth in the continental crust

NASA Astrophysics Data System (ADS)

Yang, Xin-Yue

Petrologic and geochemical changes in ductile shear zones are important for understanding deformational and geochemical processes of the continental crust. This study examines three shear zones that formed under conditions varying from lower greenschist facies to upper amphibolite facies in order to document the petrologic and geochemical changes of deformed rocks at various metamorphic grades. The studied shear zones include two greenschist facies shear zones in the southern Appalachians and an upper amphibolite facies shear zone in southern Ontario. The mylonitic gneisses and mylonites in the Roses Mill shear zone of central Virginia are derived from a ferrodiorite protolith and characterized by a lower greenschist facies mineral assemblage. Both pressure solution and recrystallization were operative deformation mechanisms during mylonitization in this shear zone. Strain-driven dissolution and solution transfer played an important role in the mobilization of felsic components (Si, Al, K, Na, and Ca). During mylonitization, 17% to 32% bulk rock volume losses of mylonites are mainly attributed to removal of these mobile felsic components by a fluid phase. Mafic components (Fe, Mg, Ti, Mn and P) and trace elements, REE, Y, V and Sc, were immobile. At Rosman, North Carolina, the Brevard shear zone (BSZ) shows a deformational transition from the coarse-grained Henderson augen gneiss (HAG) to proto-mylonite, mylonite and ultra-mylonite. The mylonites contain a retrograde mineral assemblage as a product of fluid-assisted chemical breakdown of K-feldspar and biotite at higher greenschist facies conditions. Recrystallization and intra-crystalline plastic deformation are major deformation mechanisms in the BSZ. Fluid-assisted mylonitization in the BSZ led to 6% to 23% bulk volume losses in mylonites. During mylonitization, both major felsic and mafic elements and trace elements, Rb, Sr, Zr, V, Sc, and LREE were mobile; however, the HREEs were likely immobile. A shear zone in the Parry Sound domain, Ontario, formed at upper amphibolite facies conditions. The deformation process of the shear zone involves fully plastic deformation and high-temperature dynamic recrystallization and annealing recovery of both quartz and plagioclase. Geochemical evidence indicates that the chemical changes in the deformed rocks resulted from mixing of mafic and felsic layers together with fluid-assisted mass transfer within the shear zone. A geochemical model that incorporates closed-system two-component mixing with open-system mass transfer can well explain the observed major and trace element data.

Implications of Eocene-age Philippine Sea and forearc basalts for initiation and early history of the Izu-Bonin-Mariana arc

NASA Astrophysics Data System (ADS)

Yogodzinski, Gene M.; Bizimis, Michael; Hickey-Vargas, Rosemary; McCarthy, Anders; Hocking, Benjamin D.; Savov, Ivan P.; Ishizuka, Osamu; Arculus, Richard

2018-05-01

Whole-rock isotope ratio (Hf, Nd, Pb, Sr) and trace element data for basement rocks at ocean drilling Sites U1438, 1201 and 447 immediately west of the KPR (Kyushu-Palau Ridge) are compared to those of FAB (forearc basalts) previously interpreted to be the initial products of IBM subduction volcanism. West-of-KPR basement basalts (drill sites U1438, 1201, 447) and FAB occupy the same Hf-Nd and Pb-Pb isotopic space and share distinctive source characteristics with εHf mostly > 16.5 and up to εHf = 19.8, which is more radiogenic than most Indian mid-ocean ridge basalts (MORB). Lead isotopic ratios are depleted, with 206Pb/204Pb = 17.8-18.8 accompanying relatively high 208Pb/204Pb, indicating an Indian-MORB source unlike that of West Philippine Basin plume basalts. Some Sr isotopes show affects of seawater alteration, but samples with 87Sr/86Sr < 0.7034 and εNd > 8.0 appear to preserve magmatic compositions and also indicate a common source for west-of-KPR basement and FAB. Trace element ratios resistant to seawater alteration (La/Yb, Lu/Hf, Zr/Nb, Sm/Nd) in west-of-KPR basement are generally more depleted than normal MORB and so also appear similar to FAB. At Site U1438, only andesite sills intruding sedimentary rocks overlying the basement have subduction-influenced geochemical characteristics (εNd ∼ 6.6, εHf ∼ 13.8, La/Yb > 2.5, Nd/Hf ∼ 9). The key characteristic that unites drill site basement rocks west of KPR and FAB is the nature of their source, which is more depleted in lithophile trace elements than average MORB but with Hf, Nd, and Pb isotope ratios that are common in MORB. The lithophile element-depleted nature of FAB has been linked to initiation of IBM subduction in the Eocene, but Sm-Nd model ages and errorchron relationships in Site U1438 basement indicate that the depleted character of the rocks is a regional characteristic that was produced well prior to the time of subduction initiation and persists today in the source of modern IBM arc volcanic rocks with Sm/Nd > 0.34 and εNd ∼ 9.0.

Trace Elements in Ovaries: Measurement and Physiology.

PubMed

Ceko, Melanie J; O'Leary, Sean; Harris, Hugh H; Hummitzsch, Katja; Rodgers, Raymond J

2016-04-01

Traditionally, research in the field of trace element biology and human and animal health has largely depended on epidemiological methods to demonstrate involvement in biological processes. These studies were typically followed by trace element supplementation trials or attempts at identification of the biochemical pathways involved. With the discovery of biological molecules that contain the trace elements, such as matrix metalloproteinases containing zinc (Zn), cytochrome P450 enzymes containing iron (Fe), and selenoproteins containing selenium (Se), much of the current research focuses on these molecules, and, hence, only indirectly on trace elements themselves. This review focuses largely on two synchrotron-based x-ray techniques: X-ray absorption spectroscopy and x-ray fluorescence imaging that can be used to identify the in situ speciation and distribution of trace elements in tissues, using our recent studies of bovine ovaries, where the distribution of Fe, Se, Zn, and bromine were determined. It also discusses the value of other techniques, such as inductively coupled plasma mass spectrometry, used to garner information about the concentrations and elemental state of the trace elements. These applications to measure trace elemental distributions in bovine ovaries at high resolutions provide new insights into possible roles for trace elements in the ovary. © 2016 by the Society for the Study of Reproduction, Inc.

Simulation of Zr content in TiZrCuNi brazing filler metal for Ti6Al4V alloy

NASA Astrophysics Data System (ADS)

Yue, Xishan; Xie, Zonghong; Jing, Yongjuan

2017-07-01

To optimize the Zr content in Ti-based filler metal, the covalent electron on the nearest atoms bond in unit cell ( n A u-v ) with Ti-based BCC structure was calculated, in which the brazing temperature was considered due to its influence on the lattice parameter. Based on EET theory (The Empirical Electron Theory for solid and molecules), n_{{A}}^{{u - v}} represents the strength of the unit cell with defined element composition and structure, which reflects the effect from solid solution strengthening on the strength of the unit cell. For Ti-Zr-15Cu-10Ni wt% filler metal, it kept constant as 0.3476 with Zr as 37.5˜45 wt% and decreased to 0.333 with Zr decreasing from 37.5 to 25 wt%. Finally, it increased up to 0.3406 with Zr as 2˜10 wt%. Thus, Ti-based filler metal with Zr content being 2˜10 wt% is suggested based on the simulation results. Moreover, the calculated covalent electron of n A u-v showed good agreement with the hardness of the joint by filler 37.5Zr and 10Zr. The composition of Ti-10Zr-15Cu-10Ni wt% was verified in this study with higher tensile strength of the brazing joint and uniform microstructure of the interface.

Bulk Al-Al3Zr composite prepared by mechanical alloying and hot extrusion for high-temperature applications

NASA Astrophysics Data System (ADS)

Pourkhorshid, E.; Enayati, M. H.; Sabooni, S.; Karimzadeh, F.; Paydar, M. H.

2017-08-01

Bulk Al/Al3Zr composite was prepared by a combination of mechanical alloying (MA) and hot extrusion processes. Elemental Al and Zr powders were milled for up to 10 h and heat treated at 600°C for 1 h to form stable Al3Zr. The prepared Al3Zr powder was then mixed with the pure Al powder to produce an Al-Al3Zr composite. The composite powder was finally consolidated by hot extrusion at 550°C. The mechanical properties of consolidated samples were evaluated by hardness and tension tests at room and elevated temperatures. The results show that annealing of the 10-h-milled powder at 600°C for 1 h led to the formation of a stable Al3Zr phase. Differential scanning calorimetry (DSC) results confirmed that the formation of Al3Zr began with the nucleation of a metastable phase, which subsequently transformed to the stable tetragonal Al3Zr structure. The tension yield strength of the Al-10wt%Al3Zr composite was determined to be 103 MPa, which is approximately twice that for pure Al (53 MPa). The yield stress of the Al/Al3Zr composite at 300°C is just 10% lower than that at room temperature, which demonstrates the strong potential for the prepared composite to be used in high-temperature structural applications.

A study of the impact of moist-heat and dry-heat treatment processes on hazardous trace elements migration in food waste.

PubMed

Chen, Ting; Jin, Yiying; Qiu, Xiaopeng; Chen, Xin

2015-03-01

Using laboratory experiments, the authors investigated the impact of dry-heat and moist-heat treatment processes on hazardous trace elements (As, Hg, Cd, Cr, and Pb) in food waste and explored their distribution patterns for three waste components: oil, aqueous, and solid components. The results indicated that an insignificant reduction of hazardous trace elements in heat-treated waste-0.61-14.29% after moist-heat treatment and 4.53-12.25% after dry-heat treatment-and a significant reduction in hazardous trace elements (except for Hg without external addition) after centrifugal dehydration (P < 0.5). Moreover, after heat treatment, over 90% of the hazardous trace elements in the waste were detected in the aqueous and solid components, whereas only a trace amount of hazardous trace elements was detected in the oil component (<0.01%). In addition, results indicated that heat treatment process did not significantly reduce the concentration of hazardous trace elements in food waste, but the separation process for solid and aqueous components, such as centrifugal dehydration, could reduce the risk considerably. Finally, combined with the separation technology for solid and liquid components, dry-heat treatment is superior to moist-heat treatment on the removal of external water-soluble ionic hazardous trace elements. An insignificant reduction of hazardous trace elements in heat-treated waste showed that heat treatment does not reduce trace elements contamination in food waste considerably, whereas the separation process for solid and aqueous components, such as centrifugal dehydration, could reduce the risk significantly. Moreover, combined with the separation technology for solid and liquid components, dry-heat treatment is superior to moist-heat treatment for the removal of external water-soluble ionic hazardous trace elements, by exploring distribution patterns of trace elements in three waste components: oil, aqueous, and solid components.

Corticosterone levels in relation to trace element contamination along an urbanization gradient in the common blackbird (Turdus merula).

PubMed

Meillère, Alizée; Brischoux, François; Bustamante, Paco; Michaud, Bruno; Parenteau, Charline; Marciau, Coline; Angelier, Frédéric

2016-10-01

In a rapidly urbanizing world, trace element pollution may represent a threat to human health and wildlife, and it is therefore crucial to assess both exposition levels and associated effects of trace element contamination on urban vertebrates. In this study, we investigated the impact of urbanization on trace element contamination and stress physiology in a wild bird species, the common blackbird (Turdus merula), along an urbanization gradient (from rural to moderately urbanized areas). Specifically, we described the contamination levels of blackbirds by 4 non-essential (Ag, Cd, Hg, Pb) and 9 essential trace elements (As, Co, Cr, Cu, Fe, Mn, Ni, Se, Zn), and explored the putative disrupting effects of the non-essential element contamination on corticosterone levels (a hormonal proxy for environmental challenges). We found that non-essential trace element burden (Cd and Pb specifically) increased with increasing urbanization, indicating a significant trace element contamination even in medium sized cities and suburban areas. Interestingly, the increased feather non-essential trace element concentrations were also associated with elevated feather corticosterone levels, suggesting that urbanization probably constrains birds and that this effect may be mediated by trace element contamination. Future experimental studies are now required to disentangle the influence of multiple urban-related constraints on corticosterone levels and to specifically test the influence of each of these trace elements on corticosterone secretion. Copyright © 2016 Elsevier B.V. All rights reserved.

Ceramic Plutonium Target Development for the MASHA Separator for the Synthesis of Element 114

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaughnessy, D A; Wilk, P A; Moody, K J

2005-06-29

We are currently developing a Pu ceramic target for the MASHA mass separator. MASHA will use a Pu ceramic target capable of tolerating temperatures up to 2000 C. Reaction products will diffuse out of the target into an ion source, and transported through the separator to a position-sensitive focal-plane detector array for mass identification. Experiments on MASHA will allow us to make measurements that will cement our identification of element 114 and provide data for future experiments on chemical properties of the heaviest elements. In this study (Sm,Zr)O{sub 2-x} ceramics are produced and evaluated for studies on the production ofmore » Pb (homolog of element 114) by the reaction of Ca on Sm. This work will provide an initial analysis on the feasibility of using a ZrO{sub 2}-PuO{sub 2} as a target for the production of element 114.« less

Radial flow nuclear thermal rocket (RFNTR)

DOEpatents

Leyse, Carl F.

1995-11-07

A radial flow nuclear thermal rocket fuel assembly includes a substantially conical fuel element having an inlet side and an outlet side. An annular channel is disposed in the element for receiving a nuclear propellant, and a second, conical, channel is disposed in the element for discharging the propellant. The first channel is located radially outward from the second channel, and separated from the second channel by an annular fuel bed volume. This fuel bed volume can include a packed bed of loose fuel beads confined by a cold porous inlet frit and a hot porous exit frit. The loose fuel beads include ZrC coated ZrC-UC beads. In this manner, nuclear propellant enters the fuel assembly axially into the first channel at the inlet side of the element, flows axially across the fuel bed volume, and is discharged from the assembly by flowing radially outward from the second channel at the outlet side of the element.

Radial flow nuclear thermal rocket (RFNTR)

DOEpatents

Leyse, Carl F.

1995-01-01

A radial flow nuclear thermal rocket fuel assembly includes a substantially conical fuel element having an inlet side and an outlet side. An annular channel is disposed in the element for receiving a nuclear propellant, and a second, conical, channel is disposed in the element for discharging the propellant. The first channel is located radially outward from the second channel, and separated from the second channel by an annular fuel bed volume. This fuel bed volume can include a packed bed of loose fuel beads confined by a cold porous inlet frit and a hot porous exit frit. The loose fuel beads include ZrC coated ZrC-UC beads. In this manner, nuclear propellant enters the fuel assembly axially into the first channel at the inlet side of the element, flows axially across the fuel bed volume, and is discharged from the assembly by flowing radially outward from the second channel at the outlet side of the element.

A Method for Assessing the Retention of Trace Elements in Human Body Using Neural Network Technology

PubMed Central

Ragimov, Aligejdar; Faizullin, Rashat; Valiev, Vsevolod

2017-01-01

Models that describe the trace element status formation in the human organism are essential for a correction of micromineral (trace elements) deficiency. A direct trace element retention assessment in the body is difficult due to the many internal mechanisms. The trace element retention is determined by the amount and the ratio of incoming and excreted substance. So, the concentration of trace elements in drinking water characterizes the intake, whereas the element concentration in urine characterizes the excretion. This system can be interpreted as three interrelated elements that are in equilibrium. Since many relationships in the system are not known, the use of standard mathematical models is difficult. The artificial neural network use is suitable for constructing a model in the best way because it can take into account all dependencies in the system implicitly and process inaccurate and incomplete data. We created several neural network models to describe the retentions of trace elements in the human body. On the model basis, we can calculate the microelement levels in the body, knowing the trace element levels in drinking water and urine. These results can be used in health care to provide the population with safe drinking water. PMID:29065586

Assessment of trace element impacts on agricultural use of water from the Dan River following the Eden coal ash release.

PubMed

Hesterberg, Dean; Polizzotto, Matthew L; Crozier, Carl; Austin, Robert E

2016-04-01

Catastrophic events require rapid, scientifically sound decision making to mitigate impacts on human welfare and the environment. The objective of this study was to analyze potential impacts of coal ash-derived trace elements on agriculture following a 35,000-tonne release of coal ash into the Dan River at the Duke Energy Steam Station in Eden, North Carolina. We performed scenario calculations to assess the potential for excessive trace element loading to soils via irrigation and flooding with Dan River water, uptake of trace elements by crops, and livestock consumption of trace elements via drinking water. Concentrations of 13 trace elements measured in Dan River water samples within 4 km of the release site declined sharply after the release and were equivalent within 5 d to measurements taken upriver. Mass-balance calculations based on estimates of soil trace-element concentrations and the nominal river water concentrations indicated that irrigation or flooding with 25 cm of Dan River water would increase soil concentrations of all trace elements by less than 0.5%. Calculations of potential increases of trace elements in corn grain and silage, fescue, and tobacco leaves suggested that As, Cr, Se, Sr, and V were elements of most concern. Concentrations of trace elements measured in river water following the ash release never exceeded adopted standards for livestock drinking water. Based on our analyses, we present guidelines for safe usage of Dan River water to diminish negative impacts of trace elements on soils and crop production. In general, the approach we describe here may serve as a basis for rapid assessment of environmental and agricultural risks associated with any similar types of releases that arise in the future. © 2015 SETAC.

Reconstructing Eolian Delivery to the Ulleung Basin (IODP Site U1430) Over the Past 12 Myr

NASA Astrophysics Data System (ADS)

Anderson, C. H.; Dunlea, A. G.; Murray, R. W.; Tada, R.; Alvarez Zarikian, C. A.

2017-12-01

Spring storms associated with the seasonal phases of the East Asian Monsoon (EAM), transport dust seaward and influence marine sedimentation in adjacent ocean regions. Here, we aim to track changes in the intensity of the EAM since the late Miocene by examining the relative proportions and sources of eolian inputs in marine sediment records. We use bulk sediment recovered from Site U1430 in the Ulleung Basin during Integrated Ocean Drilling Program Expedition 346 in 2013 to examine changes in the EAM over the past 12 Myr. Sediment recovered at this site is clayey silt, nannofossil and diatom oozes, claystone, and basal glauonitic sandstone. We analyze major, trace, and rare earth element concentrations for 72 bulk sediment samples analyzed by ICP-ES and ICP-MS, and interpret this dataset using a variety of multivariate statistical partitioning techniques (Q-mode Factor Analyses (QFA), Multiple Linear Regressions) to investigate sediment provenance. Sedimentologic observations and elemental concentrations indicate the presence of biogenic siliceous and carbonaceous components mixed with aluminosilicates. For example, Si/Al (g/g) reaches local maxima at 3 Ma and 10 Ma in several diatom rich sections, and Ca/Al (g/g) exhibits a peak at 0.58 Ma. Other downhole element ratios exhibit subtle variations, including Ti/Al of 0.05 +/- 0.004 g/g, Sc/Al 2 +/- 0.2 ug/g, and Rb/Al 17 +/- 1.5 ug/g. When plotted in ternary diagrams, samples exhibit offset arrays (La-Th-Sc) or multiple clusters (Zr-Nb-Sc) from an Upper Continental Crust and Mid-Ocean Ridge Basalt mixing line. In Th-Cr-Nb, the data exhibit a V-shaped array. The range of geochemical variability suggests that multiple sources of terrigenous matter and/or volcanic ash are being delivered to the site. The multivariate statistics also indicate the mixing of multiple aluminosilicate sources. Focusing on a suite of seven elements (Al, Ti, Sc, Cr, Rb, Th, La), preliminary QFA suggest that five factors are required to explain 99% of the variability in the dataset. Factors group different co-varying elements: Factor 1 Zr and Th, Factor 2 only Cr, Factor 3 Sc and La, Factor 4 Al and Sc, and Factor 5 with Rb and Th. Terrigenous inputs are likely from several sources including loess and other continental crustal material, and will be discussed further.

Synthesis and magnetic properties of Zr doped ZnO Nanoparticles.

PubMed

Zhang, Jing; Gao, Daqiang; Yang, Guijin; Zhang, Jinlin; Shi, Zhenhua; Zhang, Zhaohui; Zhu, Zhonghua; Xue, Desheng

2011-11-10

Zr doped ZnO nanoparticles are prepared by the sol-gel method with post-annealing. X-ray diffraction results show that all samples are the typical hexagonal wurtzite structure without any other new phase, as well as the Zr atoms have successfully entered into the ZnO lattices instead of forming other lattices. Magnetic measurements indicate that all the doping samples show room temperature ferromagnetism and the pure ZnO is paramagneism. The results of Raman and X-ray photoelectron spectroscopy indicate that there are a lot of oxygen vacancies in the samples by doping element of Zr. It is considered that the observed ferromagnetism is related to the doping induced oxygen vacancies.

New Perspectives on the Essential Trace Elements.

ERIC Educational Resources Information Center

Frieden, Earl

1985-01-01

Provides a comprehensive overview of the 19 essential trace elements, examining: the concept of essentiality; evolution of these elements; possible future essential elements; the lanthanides and actinides; how essential trace elements work; the metalloenzymes; the nonmetals; iodine and the thyroid hormones; and antagonism among these elements. (JN)

Synergistic effect of PANI-ZrO2 composite as antibacterial, anti-corrosion, and phosphate adsorbent material: synthesis, characterization and applications.

PubMed

Masim, Frances Camille P; Tsai, Cheng-Hsien; Lin, Yi-Feng; Fu, Ming-Lai; Liu, Minghua; Kang, Fei; Wang, Ya-Fen

2017-11-03

The increasing number of bacteria-related problems and presence of trace amounts of phosphate in treated wastewater effluents have become a growing concern in environmental research. The use of antibacterial agents and phosphate adsorbents for the treatment of wastewater effluents is of great importance. In this study, the potential applications of a synthesized polyaniline (PANI)-zirconium dioxide (ZrO 2 ) composite as an antibacterial, phosphate adsorbent and anti-corrosion material were systematically investigated. The results of an antibacterial test reveal an effective area of inhibition of 14 and 18 mm for the Escherichia coli and Staphylococcus aureus bacterial strains, respectively. The antibacterial efficiency of the PANI-ZrO 2 composite is twice that of commercial ZrO 2 . In particular, the introduction of PANI increased the specific surface area and roughness of the composite material, which was beneficial to increase the contact area with bacterial and phosphate. The experimental results demonstrated that phosphate adsorption studies using 200 mg P/L phosphate solution showed a significant phosphate removal efficiency of 64.4%, and the maximum adsorption capacity of phosphate on the solid surface of PANI-ZrO 2 is 32.4 mg P/g. Furthermore, PANI-ZrO 2 coated on iron substrate was tested for anti-corrosion studies by a natural salt spray test (7.5% NaCl), which resulted in the formation of no rust. To the best of our knowledge, no works have been reported on the synergistic effects of the PANI-ZrO 2 composite as an antibacterial, anti-corrosion, and phosphate adsorbent material. PANI-ZrO 2 composite is expected to be a promising comprehensive treatment method for water filters in the aquaculture industry and for use in water purification applications.

Trace element contaminants in mineral fertilizers used in Iran.

PubMed

Latifi, Zahra; Jalali, Mohsen

2018-05-25

The application of mineral fertilizers which have contaminants of trace elements may impose concern regarding the entry and toxic accumulation of these elements in agro-ecosystems. In this study, 57 mineral fertilizers (nitrogen, potassium, phosphate, and compound fertilizers) distributed in Iran were analyzed for their contents of Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and Fe. The results revealed that the contents of these trace elements varied considerably depending on the type of the element and the fertilizer. Among these elements, Fe displayed the highest average content, whereas Cd showed the lowest. Generally, the trace element contents in P-containing fertilizers were higher than those in nitrogen and potassium fertilizers. The mean values of trace elements (mg kg -1 ) in P-containing fertilizers were 4.0 (Cd), 5.5 (Co), 35.7 (Cr), 24.4 (Cu), 272 (Mn), 14.3 (Ni), 6.0 (Pb), 226 (Zn), and 2532 (Fe). Comparing trace element contents to limit values set by the German Fertilizer Ordinance showed that the mean contents of potentially toxic trace elements, such as Cd and Pb, were lower than their limit values in all groups of fertilizers. On the other hand, while a number of fertilizers contained a high content of some essential trace elements, particularly Fe, they were not labeled as such.

Analysis of trace metals in water by inductively coupled plasma emission spectrometry using sodium dibenzyldithiocarbamate for preconcentration

USGS Publications Warehouse

Smith, C.L.; Motooka, J.M.; Willson, W.R.

1984-01-01

Since concentrations of trace elements in most natural waters seldom exceed the ??g/L level, analysis of trace elements in natural waters by inductively coupled plasma emission spectrometry (ICP) requires a preconcentration procedure. The elements Ag, Bi, Cd, Co, Cu, Fe, Mo, Ni, Pb, Sn, V, W, and Zn were separated and concentrated from 500 mL of water by coprecipitating them with sodium dibenzyldithiocarbamate (NaDBDTC) using nickel or silver as a carrier. The precipitated trace elements were collected on a membrane filter, redissolved from the filter with hot nitric and hydrochloric acids, and analyzed using ICP. Recoveries for all the trace elements except tungsten exceeded 80%. Coprecipitation of trace elements with NaDBDTC eliminated the use of difficult-to-inject organic solvents, and NaDBDTC coprecipitated a wider array of trace elements than ammoniumpyrrolidinedithiocarbamate (APDC), another commonly used coprecipitate.

Composition of basaltic lavas sampled by phase-2 of the Hawaii Scientific Drilling Project: Geochemical stratigraphy and magma types

NASA Astrophysics Data System (ADS)

Rhodes, J. M.; Vollinger, M. J.

2004-03-01

This paper presents major and trace element compositions of lavas from the entire 3098 m stratigraphic section sampled by phase-2 of the Hawaii Scientific Drilling Project. The upper 245 m are lavas from Mauna Loa volcano, and the lower 2853 m are lavas and volcanoclastic rocks from Mauna Kea volcano. These intervals are inferred to represent about 100 ka and 400 ka respectively of the eruptive history of the two volcanoes. The Mauna Loa tholeiites tend to be higher in SiO2 and lower in total iron, TiO2, alkalis, and incompatible elements at a given MgO content than Mauna Kea lavas. The transition from Mauna Loa to Mauna Kea lavas is all the more pronounced because the Mauna Loa tholeiites overlie a thin sequence of postshield Mauna Kea alkalic to transitional tholeiitic lavas. The Mauna Loa tholeiites display well-developed coherent trends with MgO that are indistinguishable in most respects from modern lavas. With depth, however, there is a slight decline in incompatible element abundances, and small shifts to depleted isotopic ratios. These characteristics suggest small changes in melt production and source components over time, superimposed on shallow melt segregation. The Mauna Kea section is subdivided into a thin, upper 107 m sequence of postshield tholeiites, transitional tholeiites and alkali basalts of the Hamakua volcanics, overlying four tholeiitic magma types that are intercalated throughout the rest of the core. These four magma types are recognized on the basis of MgO-normalized SiO2 and Zr/Nb values. Type-1 lavas (high SiO2 and Zr/Nb) are ubiquitous below the postshield lavas and are the dominant magma type on Mauna Kea. They are inter-layered with the other three lava types. Type-2 lavas (low SiO2 but high Zr/Nb) are found only in the upper core, and especially above 850 m. Type-3 lavas (low SiO2 and Zr/Nb) are very similar to tholeiites from Loihi volcano and are present only below 1974 m. There are only 3 discrete samples of type-4 lavas (high SiO2 and low Zr/Nb), which are present in the upper and lower core. The differences between these magma types are inferred to reflect changes in melt production, depth of melt segregation, and differences in plume source components over about 400 ka of Mauna Kea's eruptive history. At the start of this record, eruption rates were high, and two distinct tholeiitic magmas (type-1 and 3) were erupting concurrently. These two magmas require two distinct source components, one similar to that of modern Loihi tholeiites and the other close to that of Kilauea magmas. Subsequently, the Loihi-like source of the type-3 magmas was exhausted, and these lavas are absent from the remainder of the core. For the next 200 ka or so, the eruptive sequence consists of inter-layered type-1 and -2 lavas that are derived from a common Mauna Kea source, the major difference between the two being the depth at which the melts segregated from the source. At around 440 ka (corresponding with the transition in the core from submarine to subaerial lavas) eruption rates began to decline and low-MgO lavas are suddenly much more abundant in the record. Continuing gradual decline in melting and eruption rates was accompanied by a decline in normalized SiO2 content of the type-1 magmas, and the eventual onset of postshield magmatism.

Geochemistry of the Shuksan greenschists and blueschists, North Cascades, Washington: Variably fractionated and altered metabasalts of oceanic affinity

NASA Astrophysics Data System (ADS)

Dungan, M. A.; Vance, J. A.; Blanchard, D. P.

1983-06-01

The Shuksan schist comprises a structurally coherent, metabasaltic member of the Easton Formation, the uppermost allochthon (Shuksan thrust plate) in the thrust system of the western North Cascades of Washington State. Late Jurassic metamorphism at moderately high P/T produced interlayering of actinolite-bearing greenschist assemblages with blue amphibole-bearing rocks. Major and trace element analyses of twelve greenschist and blueschist samples have been used to establish similarities between the basaltic protolith and moderately to strongly fractionated Type I MORB, to distinguish the effects of seafloor alteration superimposed on the primary igneous chemistry, and to evaluate the origin and nature of the chemical controls which produced the two mineral assemblages. The twelve analyzed samples exhibit moderate to strong LREE depletion, and characteristically low concentrations of other non-labile trace elements such as Nb, Th and Hf. The highly to moderately incompatible elements Ti, P, Nb, Zr, Hf, Y, Sc, and the REE vary by factors of 1.5 to 3.5 within the suite in a systematic pattern, increasing smoothly with increasing total iron. The relative enrichments of these elements are inversely proportional to bulk partition coefficients estimated for fractionation of basaltic magmas. The magnitude of the negative europium anomaly increases with overall incompatible element enrichment. These variations are consistent with the production of a wide spectrum of compositions by different degrees of low pressure fractionation of similar Type I MORB parent magmas. The concentrations of Sr, Rb, Na, and K vary irregularly and do not correlate with the non-labile trace elements. K and Rb are substantially elevated over typical MORB values in most samples and exhibit a consistently lower ratio (K/Rb=400 vs 1000) than fresh MORB. Concentrations of these four elements are believed to have been modified by low temperature seafloor alteration (pre-metamorphic) characterized by the formation of K-rich celadonitic clays, palagonite and minor potassium feldspar. The critical chemical variables that control the occurrence of actinolite and blue amphibole in the Shuksan schists are total iron, Fe2O3-content and Na/Ca (all high in blueschists). The chemical features were largely established by magmatic processes and inherited from the igneous parent rocks; the chemically more evolved samples are blueschists. The Fe2O3-content and Na/Ca, however, may be modified during alteration, rendering initial bulk compositions near the chemical boundary susceptible to changes which may shift rock compositions from one compatibility field to the other. Heterogeneous alteration of pillow lavas and other fragmental deposits, followed by intense flattening during metamorphism, provides a mechanism for generating blueschists and greenschists interlayered on the cm scale.

Linking trace element variations with macronutrients and major cations in marine mussels Mytilus edulis and Perna viridis.

PubMed

Liu, Fengjie; Wang, Wen-Xiong

2015-09-01

Marine mussels have long been used as biomonitors of contamination of trace elements, but little is known about whether variation in tissue trace elements is significantly associated with those of macronutrients and major cations. The authors examined the variability of macronutrients and major cations and their potential relationships with bioaccumulation of trace elements. The authors analyzed the concentrations of macronutrients (C, N, P, S), major cations (Na, Mg, K, Ca), and trace elements (Al, V, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Pb) in the whole soft tissues of marine mussels Mytilus edulis and Perna viridis collected globally from 21 sites. The results showed that 12% to 84% of the variances in the trace elements was associated with major cations, and the tissue concentration of major cations such as Na and Mg in mussels was a good proxy for ambient seawater concentrations of the major cations. Specifically, bioaccumulation of most of the trace elements was significantly associated with major cations, and the relationships of major cations with trace cations and trace oxyanions were totally opposite. Furthermore, 14% to 69% of the variances in the trace elements were significantly associated with macronutrients. Notably, more than half of the variance in the tissue concentrations of As, Cd, V, Ba, and Pb was explained by the variance in macronutrients in one or both species. Because the tissue macronutrient concentrations were strongly associated with animal growth and reproduction, the observed coupling relationships indicated that these biological processes strongly influenced the bioaccumulation of some trace elements. The present study indicated that simultaneous quantification of macronutrients and major cations with trace elements can improve the interpretation of biomonitoring data. © 2015 SETAC.

Modeling deformation behavior of Cu-Zr-Al bulk metallic glass matrix composites

NASA Astrophysics Data System (ADS)

Pauly, S.; Liu, G.; Wang, G.; Das, J.; Kim, K. B.; Kühn, U.; Kim, D. H.; Eckert, J.

2009-09-01

In the present work we prepared an in situ Cu47.5Zr47.5Al5 bulk metallic glass matrix composite derived from the shape memory alloy CuZr. We use a strength model, which considers percolation and a three-microstructural-element body approach, to understand the effect of the crystalline phase on the yield stress and the fracture strain under compressive loading, respectively. The intrinsic work-hardenability due to the martensitic transformation of the crystalline phase causes significant work hardening also of the composite material.

Hydrothermal synthesis of copper zirconium phosphate hydrate [Cu(OH)2Zr(HPO4)2·2H2O] and an investigation of its lubrication properties in grease.

PubMed

Zhang, Xiaosheng; Xu, Hong; Zuo, Zhijun; Lin, Zhi; Ferdov, Stanislav; Dong, Jinxiang

2013-08-28

Copper zirconium phosphate hydrate (Cu(OH)2Zr(HPO4)2·2H2O, hereafter referred to as Cu-α-ZrP) with high crystallinity was directly synthesized in a NaF-CuO-ZrO-P2O5-H2O system under hydrothermal conditions. The copper ion was confirmed to be an exchangeable cation in the Cu-α-ZrP through elemental analysis and a proton ion exchange process. The crystal structure of the Cu-α-ZrP was determined ab initio by using X-ray powder diffraction data. In the structure, the CuO6 octahedron would be located in an exchangeable atom position. Moreover, Cu-α-ZrP was evaluated as an additive in grease in a four ball test. The maximum nonseizure load (PB, representing the load-carrying capacity) of the base grease containing Cu-α-ZrP was increased from 353 to 1235 N. The excellent load-carrying capacity may be explained by the easier adherence of the material to the worn surface forming a tight protective film.

[Proposal of new trace elements classification to be used in nutrition, oligotherapy and other therapeutics strategies].

PubMed

Ramírez Hernández, Javier; Bonete Pérez, María José; Martínez Espinosa, Rosa María

2014-12-17

1) to propose a new classification of the trace elements based on a study of the recently reported research; 2) to offer detailed and actualized information about trace elements. the analysis of the research results recently reported reveals that the advances of the molecular analysis techniques point out the importance of certain trace elements in human health. A detailed analysis of the catalytic function related to several elements not considered essential o probably essentials up to now is also offered. To perform the integral analysis of the enzymes containing trace elements informatics tools have been used. Actualized information about physiological role, kinetics, metabolism, dietetic sources and factors promoting trace elements scarcity or toxicity is also presented. Oligotherapy uses catalytic active trace elements with therapeutic proposals. The new trace element classification here presented will be of high interest for different professional sectors: doctors and other professions related to medicine; nutritionist, pharmaceutics, etc. Using this new classification and approaches, new therapeutic strategies could be designed to mitigate symptomatology related to several pathologies, particularly carential and metabolic diseases. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Brazing characteristics of a Zr-Ti-Cu-Fe eutectic alloy filler metal for Zircaloy-4

NASA Astrophysics Data System (ADS)

Lee, Jung G.; Lim, C. H.; Kim, K. H.; Park, S. S.; Lee, M. K.; Rhee, C. K.

2013-10-01

A Zr-Ti-Cu-Fe quaternary eutectic alloy was employed as a new Be-free brazing filler metal for Zircaloy-4 to supersede physically vapor-deposited Be coatings used conventionally with several disadvantages. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) showing a low melting temperature range from 832 °C to 853 °C was designed by a partial substitution of Zr with Ti based on a Zr-Cu-Fe ternary eutectic system. By applying an alloy ribbon with the determined composition, a highly reliable joint was obtained with a homogeneous formation of predominantly grown α-Zr phases owing to a complete isothermal solidification, exhibiting strength higher than that of Zircaloy-4. The homogenization of the joint was rate-controlled by the diffusion of the filler elements (Ti, Cu, and Fe) into the Zircaloy-4 base metal, and the detrimental segregation of the Zr2Fe phase in the central zone was completely eliminated by an isothermal holding at a brazing temperature of 920 °C for 10 min.

Trace elements have limited utility for studying migratory connectivity in shorebirds that winter in Argentina

USGS Publications Warehouse

Torres-Dowdall, J.; Farmer, A.H.; Abril, M.; Bucher, E.H.; Ridley, I.

2010-01-01

Trace-element analysis has been suggested as a tool for the study of migratory connectivity because (1) trace-element abundance varies spatially in the environment, (2) trace elements are assimilated into animals' tissues through the diet, and (3) current technology permits the analysis of multiple trace elements in a small tissue sample, allowing the simultaneous exploration of several elements. We explored the potential of trace elements (B, Na, Mg, Al, Si, P, S, K, Ca, Ti, Cr, Mn, Ni, Cu, Zn, As, Sr, Cs, Hg, Tl, Pb, Bi, Th, and U) to clarify the migratory connectivity of shorebirds that breed in North America and winter in southern South America. We collected 66 recently replaced secondary feathers from Red Knots (Calidris canutus) at three sites in Patagonia and 76 from White-rumped Sandpipers (C. fuscicollis) at nine sites across Argentina. There were significant differences in trace-element abundance in shorebird feathers grown at different nonbreeding sites, and annual variability within a site was small compared to variability among sites. Across Argentina, there was no large-scale gradient in trace elements. The lack of such a gradient restricts the application of this technique to questions concerning the origin of shorebirds to a small number of discrete sites. Furthermore, our results including three additional species, the Pectoral Sandpiper (C. melanotos), Wilson's Phalarope (Phalaropus tricolor), and Collared Plover (Charadrius collaris), suggest that trace-element profiles change as feathers age. Temporal instability of trace-element values could undermine their application to the study of migratory connectivity in shorebirds. ?? The Cooper Ornithological Society 2010.

Spatial and temporal distribution of metals in suspended particulate matter of the Kali estuary, India

NASA Astrophysics Data System (ADS)

Suja, S.; Kessarkar, Pratima M.; Fernandes, Lina L.; Kurian, Siby; Tomer, Arti

2017-09-01

Major (Al, Fe, Mn, Ti, Mg) and trace (Cu, Zn, Pb, Cr, Ni, Co, Zr, Rb, Sr, Ba, Li, Be, Sc, V, Ga, Nb, Mo, Sn, Sb, Cs, Hf, Ta, Bi, Th, U) elements and particulate organic carbon (POC) concentrations in surface suspended particulate matter (SPM) of the Kali estuary, (central west coast of India) were studied during the pre-monsoon, monsoon and post monsoon seasons to infer estuarine processes, source of SPM and Geoaccumulation Index (Igeo) assigned pollutionIgeo levels. Distribution of SPM indicates the presence of the estuarine turbidity maximum (ETM) during all three seasons near the river mouth and a second ETM during the post monsoon time in the upstream associated with salinities gradient. The SPM during the monsoon is finer grained (avg. 53 μm), characterized by uniformly low normalized elemental concentration, whereas the post and pre monsoon are characterized by high normalized elemental concentration with coarser grain size (avg. 202 μm and 173 μm respectively) with highest ratios in the upstream estuary. The elemental composition and principal component analysis for the upstream estuary SPM support more contribution from the upstream catchment area rocks during the monsoon season; there is additional contribution from the downstream catchment area during the pre and post monsoon period due to the tidal effect. The Kali estuarine SPM has higher Al, Fe, Mn, Ti, Mg, Ni, Co, Ba, Li and V with respect to Average World River SPM (WRSPM). Igeo values for the SPM indicate Kali Estuary to be severely enriched with Mn and moderately enriched with Cu, Zn, Ni, Co, U and Mo in the upstream estuary during pre and post monsoon seasons. Seasonal changes in salinity gradient (reduced freshwater flow due to closing of the dam gates), reduced velocity at meandering region of the estuary and POC of 1.6-2.3% resulted in co-precipitation of trace elements that were further fortified by flocculation and coagulation throughout the water column resulting in metal trapping in the upstream region.

Low-temperature alteration of dredged volcanics from the Southern Chile Ridge: Additional information about early stages of seafloor weathering

USGS Publications Warehouse

Pichler, T.; Ridley, W.I.; Nelson, E.

1999-01-01

A suite of submarine volcanic rocks from the Southern Chile Ridge has been examined in order to investigate the early stages of low temperature alteration. Alteration in these samples proceeded as follows: (1) Fe-staining on sample surface and along fractures, (2) filling of vesicles with secondary material, (3) breakdown of glassy matrix, (4) breakdown of microcrystalline matrix, and (5) breakdown and replacement of olivine. Plagioclase and pyroxene were sometimes found to be slightly altered along internal fissures. Secondary or alteration phases generally showed high K (3-5 wt.%), Fe (30-70 wt.%) and low Al ( Rb > K. During initial stages of alteration the behavior of some trace elements such as rare-earth elements (REE), Ba, Zr, Hf, Ta, Nb, and Mo are solely controlled by the precipitation of Mn-rich Fe-oxyhydroxides. The preferred incorporation of Ce into Mn-rich Fe-oxyhydroxides may be a principal factor explaining the Ce depletion in seawater. We conclude that the earliest stages of submarine weathering are controlled by Eh and pH gradients between the rock and seawater. In the absence of a buffer, oxidation of ferrous iron causes a decrease in solution pH.

The Quaternary calc-alkaline volcanism of the Patagonian Andes close to the Chile triple junction: geochemistry and petrogenesis of volcanic rocks from the Cay and Maca volcanoes (˜45°S, Chile)

NASA Astrophysics Data System (ADS)

D'Orazio, M.; Innocenti, F.; Manetti, P.; Tamponi, M.; Tonarini, S.; González-Ferrán, O.; Lahsen, A.; Omarini, R.

2003-08-01

Major- and trace-element, Sr-Nd isotopes, and mineral chemistry data were obtained for a collection of volcanic rock samples erupted by the Cay and Maca Quaternary volcanoes, Patagonian Andes (˜45°S, Chile). Cay and Maca are two large, adjacent stratovolcanoes that rise from the Chiloe block at the southern end of the southern volcanic zone (SVZ) of the Andes. Samples from the two volcanoes are typical medium-K, calc-alkaline rocks that form two roughly continuous, largely overlapping series from subalkaline basalt to dacite. The overall geochemistry of the samples studied is very similar to that observed for most volcanoes from the southern SVZ. The narrow range of Sr-Nd isotope compositions ( 87Sr/ 86Sr=0.70389-0.70431 and 143Nd/ 144Nd=0.51277-0.51284) and the major- and trace-element distributions indicate that the Cay and Maca magmas differentiated by crystal fractionation without significant contribution by crustal contamination. This is in accordance with the thin (<30 km), relatively young (Paleozoic or more recent) continental crust beneath the volcanoes. The nature of the subduction-derived materials involved in the genesis of the Cay and Maca magmas is investigated by means of the relative concentration of fluid mobile (e.g. Ba) and fluid immobile (e.g. Nb, Ta, Zr, Y) elements and other relevant trace-element ratios (e.g. Sr/Y). The results indicate that small amounts (<1 wt%) of both subducted sediments and slab-released fluids were added to the mantle sources of the Cay and Maca volcanoes and that, despite the very young age (<10 Ma) of the oceanic lithosphere subducted beneath the volcanoes, slab melts were not involved in the magma genesis. Notwithstanding the proximity of the Cay and Maca magma sources to the northern edge of the slab window generated by the subduction of the Chile ridge under the South American plate, we did not find any geochemical evidence for a contribution of a subslab asthenospheric mantle. However, this mantle has been used to explain the peculiar geochemical features (e.g. the mild alkalinity and relatively low ratios between large ion lithophile and high field strength elements) of the Hudson volcano, which is located even closer to the slab window than the Cay and Maca volcanoes are.

Multidisciplinary work on barium contamination of the karstic upper Kupa River drainage basin (Croatia and Slovenia); calling for watershed management.

PubMed

Francisković-Bilinski, S; Bilinski, H; Grbac, R; Zunić, J; Necemer, M; Hanzel, D

2007-02-01

The present work was designed as an extension of a previous study of a barium anomaly observed in stream sediments of the Kupa River. In its upper part the Kupa River drains a region underlain by a trans-boundary aquifer. The river is a significant water resource in a region of tourism, sport, and fishing in both Croatia and Slovenia. The contamination source is situated in Homer (Lokve), Croatia, where barite was mined until 10 years ago. The barium processing waste material (<3-mm fraction) was carelessly deposited in gardens, forests, and into a sinkhole, which has an underground link with the Kupica River, a tributary of the Kupa River. Barium waste and stream sediments were analyzed using comparative techniques: X-ray diffraction (XRD), X-ray fluorescence (XRF), Mössbauer spectroscopy, and grain size analysis. XRD of the waste material identified the major minerals quartz, barite, and dolomite and the Fe-containing minor minerals muscovite and goethite. Barite was identified as a minor or trace mineral in the Kupica River sediments. XRF analysis of the waste material has shown Ba and Fe to be the predominant elements, Ca and K to be minor elements, and Mn, Zn, Sr, Pb, Co, Cu, As, Zr, Rb, Y, and Mo to be trace elements. Mössbauer spectroscopy performed at room temperature (RT) was used to study iron minerals, particularly to obtain information on the valence status of Fe ions. Grain size analysis of the waste material (<63-microm fraction) has shown that it contains 23.5% clay-size material in comparison with 7-8% clay-size material in stream sediments. It is our aim to combine geochemical and medical methods to investigate the possible impact of waste disposal on human health in Lokve. At this stage of the work, concentrations of Ba and other toxic elements in the water compartment of the Kupica River (a source of drinking water) have not been monitored by Croatian Waters (name of the Croatian water authorities). The necessity of such measurements in future studies has been highlighted. A preliminary study of diseases diagnosed in Lokve shows that about 18% of the total inhabitants have serious medical problems. Diseases of the circulatory system, endocrine, nutritional, and metabolic diseases, neoplasms, and respiratory diseases predominate. This paper calls for further multidisciplinary research on the health effects of barium and trace elements, as well as for bioremediation of contaminated gardens and for watershed management of vulnerable karstic aquifers.

Trace elements in agroecosystems and impacts on the environment.

PubMed

He, Zhenli L; Yang, Xiaoe E; Stoffella, Peter J

2005-01-01

Trace elements mean elements present at low concentrations (mg kg-1 or less) in agroecosystems. Some trace elements, including copper (Cu), zinc (Zn), manganese (Mn), iron (Fe), molybdenum (Mo), and boron (B) are essential to plant growth and are called micronutrients. Except for B, these elements are also heavy metals, and are toxic to plants at high concentrations. Some trace elements, such as cobalt (Co) and selenium (Se), are not essential to plant growth but are required by animals and human beings. Other trace elements such as cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni), mercury (Hg), and arsenic (As) have toxic effects on living organisms and are often considered as contaminants. Trace elements in an agroecosystem are either inherited from soil parent materials or inputs through human activities. Soil contamination with heavy metals and toxic elements due to parent materials or point sources often occurs in a limited area and is easy to identify. Repeated use of metal-enriched chemicals, fertilizers, and organic amendments such as sewage sludge as well as wastewater may cause contamination at a large scale. A good example is the increased concentration of Cu and Zn in soils under long-term production of citrus and other fruit crops. Many chemical processes are involved in the transformation of trace elements in soils, but precipitation-dissolution, adsorption-desorption, and complexation are the most important processes controlling bioavailability and mobility of trace elements in soils. Both deficiency and toxicity of trace elements occur in agroecosystems. Application of trace elements in fertilizers is effective in correcting micronutrient deficiencies for crop production, whereas remediation of soils contaminated with metals is still costly and difficult although phytoremediation appears promising as a cost-effective approach. Soil microorganisms are the first living organisms subjected to the impacts of metal contamination. Being responsive and sensitive, changes in microbial biomass, activity, and community structure as a result of increased metal concentration in soil may be used as indicators of soil contamination or soil environmental quality. Future research needs to focus on the balance of trace elements in an agroecosystem, elaboration of soil chemical and biochemical parameters that can be used to diagnose soil contamination with or deficiency in trace elements, and quantification of trace metal transport from an agroecosystem to the environment.

Grain-size distribution and selected major and trace element concentrations in bed-sediment cores from the Lower Granite Reservoir and Snake and Clearwater Rivers, eastern Washington and northern Idaho, 2010

USGS Publications Warehouse

Braun, Christopher L.; Wilson, Jennifer T.; Van Metre, Peter C.; Weakland, Rhonda J.; Fosness, Ryan L.; Williams, Marshall L.

2012-01-01

Fifty subsamples from 15 cores were analyzed for major and trace elements. Concentrations of trace elements were low, with respect to sediment quality guidelines, in most cores. Typically, major and trace element concentrations were lower in the subsamples collected from the Snake River compared to those collected from the Clearwater River, the confluence of the Snake and Clearwater Rivers, and Lower Granite Reservoir. Generally, lower concentrations of major and trace elements were associated with coarser sediments (larger than 0.0625 millimeter) and higher concentrations of major and trace elements were associated with finer sediments (smaller than 0.0625 millimeter).

Nuclear microscopy in trace-element biology — from cellular studies to the clinic

NASA Astrophysics Data System (ADS)

Lindh, Ulf

1993-05-01

The concentration and distribution of trace and major elements in cells are of great interest in cell biology. PIXE can provide elemental concentrations in the bulk of cells or organelles as other bulk techniques such as atomic absorption spectrophotometry and nuclear activation analysis. Supplementary information, perhaps more exciting, on the intracellular distributions of trace elements can be provided using nuclear microscopy. Intracellular distributions of trace elements in normal and malignant cells are presented. The toxicity of mercury and cadmium can be prevented by supplementation of the essential trace element selenium. Some results from an experimental animal model are discussed. The intercellular distribution of major and trace elements in isolated blood cells, as revealed by nuclear microscopy, provides useful clinical information. Examples are given concerning inflammatory connective-tissue diseases and the chronic fatigue syndrome.

Anthropogenic versus natural control on trace element and Sr-Nd-Pb isotope stratigraphy in peat sediments of southeast Florida (USA), ˜1500 AD to present

NASA Astrophysics Data System (ADS)

Kamenov, George D.; Brenner, Mark; Tucker, Jaimie L.

2009-06-01

Analysis of a well-dated peat core from Blue Cypress Marsh (BCM) provides a detailed record of natural and anthropogenic factors that controlled the geochemical cycles of a number of trace elements in Florida over the last five centuries. The trace elements were divided into "natural" and "anthropogenic" groups using concentration trends from the bottom to the top of the core. The "natural" group includes Li, Sc, Cr, Co, Ga, Ge, Zr, Nb, Cs, Ba, Hf, Y, Ta, Th, and REE (Rare Earth Elements). These elements show similar concentrations throughout the core, indicating that changes in human activities after European arrival in the "New World" did not affect their geochemical cycles. The "anthropogenic" group includes Pb, Cu, Zn, V, Sb, Sn, Bi, and Cd. Upcore enrichment of these elements indicates enhancement by anthropogenic activities. From the early 1500s to present, fluxes of the "anthropogenic" metals to the marsh increased significantly, with modern accumulation rates several-fold (e.g., V) to hundreds of times (e.g., Zn) greater than pre-colonial rates. The dominant input mechanism for trace elements from both groups to the marsh has been atmospheric deposition. Atmospheric input of a number of the elements, including the anthropogenic metals, was dominated by local sources during the last century. For several elements, long-distant transport may be important. For instance, REE and Nd isotopes provide evidence for long-range atmospheric transport dominated by Saharan dust. The greatest increase in flux of the "anthropogenic" metals occurred during the 20th century and was caused by changes in the chemical composition of atmospheric deposition entering the marsh. Increased atmospheric inputs were a consequence of several anthropogenic activities, including fossil fuel combustion (coal and oil), agricultural activities, and quarrying and mining operations. Pb and V exhibit similar trends, with peak accumulation rates in 1970. The principal anthropogenic source of V is oil combustion. The decline in V accumulation after 1970 in the BCM peat corresponds to the introduction of low-sulfur fuels and the change from heavy to distilled oils since the 1970s. After the 1920s, Pb distribution in the peat follows closely the history of alkyl lead consumption in the US, which peaked in the 1970s. Pb isotopes support this inference and furthermore, record changes in the ore sources used to produce leaded gasoline. Idaho ores dominated the peat Pb isotope record until the 1960s, followed by Pb from Mississippi Valley Type deposits from the 1960s to the 1980s. Enhanced fluxes of Cu, Zn, Cd, Sn, Sb, Bi, and to some extent Ni during the last century are likely also related to fossil fuel combustion. Local agricultural activities may also have influenced the geochemical cycles of Cu and Zn. The peat record shows enhanced U accumulation during the last century, possibly related to phosphate mining in western Florida. Sr isotopes in the peat core also reflect anthropogenic influence. The 87Sr/ 86Sr ratio decreases from natural background values in the basal part of the core to lower values in the upper part of the core. The Sr isotope shift is probably related to quarrying operations in Florida, and marks the first time an anthropogenic signal has been detected using the Sr isotope record in a peat core.

Mechanical properties, in vitro corrosion and biocompatibility of newly developed biodegradable Mg-Zr-Sr-Ho alloys for biomedical applications

PubMed Central

Ding, Yunfei; Lin, Jixing; Wen, Cuie; Zhang, Dongmei; Li, Yuncang

2016-01-01

Our previous studies have demonstrated that Mg-Zr-Sr alloys can be anticipated as excellent biodegradable implant materials for load-bearing applications. In general, rare earth elements (REEs) are widely used in magnesium (Mg) alloys with the aim of enhancing the mechanical properties of Mg-based alloys. In this study, the REE holmium (Ho) was added to an Mg-1Zr-2Sr alloy at different concentrations of Mg1Zr2SrxHo alloys (x = 0, 1, 3, 5 wt. %) and the microstructure, mechanical properties, degradation behaviour and biocompatibility of the alloys were systematically investigated. The results indicate that the addition of Ho to Mg1Zr2Sr led to the formation of the intermetallic phases MgHo3, Mg2Ho and Mg17Sr2 which resulted in enhanced mechanical strength and decreased degradation rates of the Mg-Zr-Sr-Ho alloys. Furthermore, Ho addition (≤5 wt. %) to Mg-Zr-Sr alloys led to enhancement of cell adhesion and proliferation of osteoblast cells on the Mg-Zr-Sr-Ho alloys. The in vitro biodegradation and the biocompatibility of the Mg-Zr-Sr-Ho alloys were both influenced by the Ho concentration in the Mg alloys; Mg1Zr2Sr3Ho exhibited lower degradation rates than Mg1Zr2Sr and displayed the best biocompatibility compared with the other alloys. PMID:27553403

Processing of U-2.5Zr-7.5Nb and U-3Zr-9Nb alloys by sintering process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dos Santos, A. M. M.; Ferraz, W. B.; Lameiras, F. S.

2012-07-01

To minimize the risk of nuclear proliferation, there is worldwide interest in reducing fuel enrichment of research and test reactors. To achieve this objective while still guaranteeing criticality and cycle length requirements, there is need of developing high density uranium metallic fuels. Alloying elements such as Zr, Nb and Mo are added to uranium to improve fuel performance in reactors. In this context, the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) is developing the U-2.5Zr-7.5Nb and U-3Zr-9Nb (weight %) alloys by the innovative process of sintering that utilizes raw materials in the form of powders. The powders were pressed atmore » 400 MPa and then sintered under a vacuum of about 1x10{sup -4} Torr at temperatures ranging from 1050 deg. to 1500 deg.C. The densities of the alloys were measured geometrically and by hydrostatic method and the phases identified by X ray diffraction (XRD). The microstructures of the pellets were observed by scanning electron microscopy (SEM) and the alloying elements were analyzed by energy dispersive X-ray spectroscopy (EDS). The results obtained showed the fuel density to slightly increase with the sintering temperature. The highest density achieved was approximately 80% of theoretical density. It was observed in the pellets a superficial oxide layer formed during the sintering process. (authors)« less

The Rb problem in massive AGB stars.

NASA Astrophysics Data System (ADS)

Pérez-Mesa, V.; García-Hernández, D. A.; Zamora, O.; Plez, B.; Manchado, A.; Karakas, A. I.; Lugaro, M.

2017-03-01

The asymptotic giant branch (AGB) is formed by low- and intermediate-mass stars (0.8 M_{⊙} < M < 8 M_{⊙}) in their last nuclear-burning phase, when they develop thermal pulses (TP) and suffer extreme mass loss. AGB stars are the main contributor to the enrichment of the interstellar medium (ISM) and thus to the chemical evolution of galaxies. In particular, the more massive AGB stars (M > 4 M_{⊙}) are expected to produce light (e.g., Li, N) and heavy neutron-rich s-process elements (such as Rb, Zr, Ba, Y, etc.), which are not formed in lower mass AGB stars and Supernova explosions. Classical chemical analyses using hydrostatic atmospheres revealed strong Rb overabundances and high [Rb/Zr] ratios in massive AGB stars of our Galaxy and the Magellanic Clouds (MC), confirming for the first time that the ^{22}Ne neutron source dominates the production of s-process elements in these stars. The extremely high Rb abundances and [Rb/Zr] ratios observed in the most massive stars (specially in the low-metallicity MC stars) uncovered a Rb problem; such extreme Rb and [Rb/Zr] values are not predicted by the s-process AGB models, suggesting fundamental problems in our present understanding of their atmospheres. We present more realistic dynamical model atmospheres that consider a gaseous circumstellar envelope with a radial wind and we re-derive the Rb (and Zr) abundances in massive Galactic AGB stars. The new Rb abundances and [Rb/Zr] ratios derived with these dynamical models significantly resolve the problem of the mismatch between the observations and the theoretical predictions of the more massive AGB stars.

Development of binary and ternary titanium alloys for dental implants.

PubMed

Cordeiro, Jairo M; Beline, Thamara; Ribeiro, Ana Lúcia R; Rangel, Elidiane C; da Cruz, Nilson C; Landers, Richard; Faverani, Leonardo P; Vaz, Luís Geraldo; Fais, Laiza M G; Vicente, Fabio B; Grandini, Carlos R; Mathew, Mathew T; Sukotjo, Cortino; Barão, Valentim A R

2017-11-01

The aim of this study was to develop binary and ternary titanium (Ti) alloys containing zirconium (Zr) and niobium (Nb) and to characterize them in terms of microstructural, mechanical, chemical, electrochemical, and biological properties. The experimental alloys - (in wt%) Ti-5Zr, Ti-10Zr, Ti-35Nb-5Zr, and Ti-35Nb-10Zr - were fabricated from pure metals. Commercially pure titanium (cpTi) and Ti-6Al-4V were used as controls. Microstructural analysis was performed by means of X-ray diffraction and scanning electron microscopy. Vickers microhardness, elastic modulus, dispersive energy spectroscopy, X-ray excited photoelectron spectroscopy, atomic force microscopy, surface roughness, and surface free energy were evaluated. The electrochemical behavior analysis was conducted in a body fluid solution (pH 7.4). The albumin adsorption was measured by the bicinchoninic acid method. Data were evaluated through one-way ANOVA and the Tukey test (α=0.05). The alloying elements proved to modify the alloy microstructure and to enhance the mechanical properties, improving the hardness and decreasing the elastic modulus of the binary and ternary alloys, respectively. Ti-Zr alloys displayed greater electrochemical stability relative to that of controls, presenting higher polarization resistance and lower capacitance. The experimental alloys were not detrimental to albumin adsorption. The experimental alloys are suitable options for dental implant manufacturing, particularly the binary system, which showed a better combination of mechanical and electrochemical properties without the presence of toxic elements. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Factors affecting trace element content in periurban market garden subsoil in Yunnan Province, China.

PubMed

Zu, Yanqun; Bock, Laurent; Schvartz, Christian; Colinet, Gilles; Li, Yuan

2011-01-01

Field investigations were conducted to measure subsoil trace element content and factors influencing content in an intensive periurban market garden in Chenggong County, Yunnan Province, South-West China. The area was divided into three different geomorphological units: specifically, mountain (M), transition (T) and lacustrine (L). Mean trace element content in subsoil were determined for Pb (58.2 mg/kg), Cd (0.89 mg/kg), Cu (129.2 mg/kg), and Zn (97.0 mg/kg). Strong significant relationships between trace element content in topsoil and subsoil were observed. Both Pb and Zn were accumulated in topsoil (RTS (ratio of mean trace element in topsoil to subsoil) of Pb and Zn > or =1.0) and Cd and Cu in subsoil (RTS of Cd and Cu < or = 1.0). Subsoil trace element content was related to relief, stoniness, soil color, clay content, and cation exchange capacity. Except for 7.5 YR (yellow-red) color, trace element content increased with color intensity from brown to reddish brown. Significant positive relationships were observed between Fe content and that of Pb and Cu. Trace element content in mountain unit subsoil was higher than in transition and lacustrine units (M > T > L), except for Cu (T > M > L). Mean trace element content in calcareous subsoil was higher than in sandstone and shale. Mean trace element content in clay texture subsoil was higher than in sandy and sandy loam subsoil, and higher Cu and Zn content in subsoil with few mottles. It is possible to model Pb, Cd, Cu, and Zn distribution in subsoil physico-chemical characteristics to help improve agricultural practice.

Trace elements at the intersection of marine biological and geochemical evolution

USGS Publications Warehouse

Robbins, Leslie J.; Lalonde, Stefan V.; Planavsky, Noah J.; Partin, Camille A.; Reinhard, Christopher T.; Kendall, Brian; Scott, Clinton T.; Hardisty, Dalton S.; Gill, Benjamin C.; Alessi, Daniel S.; Dupont, Christopher L.; Saito, Mak A.; Crowe, Sean A.; Poulton, Simon W.; Bekker, Andrey; Lyons, Timothy W.; Konhauser, Kurt O.

2016-01-01

Life requires a wide variety of bioessential trace elements to act as structural components and reactive centers in metalloenzymes. These requirements differ between organisms and have evolved over geological time, likely guided in some part by environmental conditions. Until recently, most of what was understood regarding trace element concentrations in the Precambrian oceans was inferred by extrapolation, geochemical modeling, and/or genomic studies. However, in the past decade, the increasing availability of trace element and isotopic data for sedimentary rocks of all ages has yielded new, and potentially more direct, insights into secular changes in seawater composition – and ultimately the evolution of the marine biosphere. Compiled records of many bioessential trace elements (including Ni, Mo, P, Zn, Co, Cr, Se, and I) provide new insight into how trace element abundance in Earth's ancient oceans may have been linked to biological evolution. Several of these trace elements display redox-sensitive behavior, while others are redox-sensitive but not bioessential (e.g., Cr, U). Their temporal trends in sedimentary archives provide useful constraints on changes in atmosphere-ocean redox conditions that are linked to biological evolution, for example, the activity of oxygen-producing, photosynthetic cyanobacteria. In this review, we summarize available Precambrian trace element proxy data, and discuss how temporal trends in the seawater concentrations of specific trace elements may be linked to the evolution of both simple and complex life. We also examine several biologically relevant and/or redox-sensitive trace elements that have yet to be fully examined in the sedimentary rock record (e.g., Cu, Cd, W) and suggest several directions for future studies.

Trace element exposure of whooper swans (Cygnus cygnus) wintering in a marine lagoon (Swan Lake), northern China.

PubMed

Wang, Feng; Xu, Shaochun; Zhou, Yi; Wang, Pengmei; Zhang, Xiaomei

2017-06-30

Trace element poisoning remains a great threat to various waterfowl and waterbirds throughout the world. In this study, we determined the trace element exposure of herbivorous whooper swans (Cygnus cygnus) wintering in Swan Lake (Rongcheng), an important swan protection area in northern China. A total of 70 samples including abiotic factors (seawater, sediments), food sources (seagrass, macroalgae), feathers and feces of whooper swans were collected from the marine lagoon during the winters of 2014/2015 and 2015/2016. Concentrations of Cu, Zn, Pb, Cr, Cd, Hg and As were determined to investigate the trace element exposure of whooper swans wintering in the area. Results showed that there was an increasing trend in sediment trace element concentrations, compared with historical data. The trace element concentrations in swan feces most closely resembled those of Zostera marina leaves, especially for Cd and Cr. The Zn and Hg concentrations in the swan feces (49.57 and 0.01mg/kg, respectively) were lower than the minimum values reported in the literature for other waterfowls, waterbirds and terrestrial birds. However, the concentrations of the other five trace elements fell within the lower and mediate range of values reported for birds across the world. These results suggest that the whooper swans wintering in Swan Lake, Rongcheng are not suffering severe trace element exposure; however, with the increasing input of trace elements to the lagoon, severe adverse impacts may occur in the future, and we therefore suggest that the input of trace elements to this area should be curbed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Heavy Metals and Related Trace Elements.

ERIC Educational Resources Information Center

Leland, Harry V.; And Others

1978-01-01

Presents a literature review of heavy metals and related trace elements in the environment, covering publications of 1976-77. This review includes: (1) trace treatment in natural water and in sediments; and (2) bioaccumulation and toxicity of trace elements. A list of 466 references is presented. (HM)

Zirconium and hafnium fractionation in differentiation of alkali carbonatite magmatic systems

NASA Astrophysics Data System (ADS)

Kogarko, L. N.

2016-05-01

Zirconium and hafnium are valuable strategic metals which are in high demand in industry. The Zr and Hf contents are elevated in the final products of magmatic differentiation of alkali carbonatite rocks in the Polar Siberia region (Guli Complex) and Ukraine (Chernigov Massif). Early pyroxene fractionation led to an increase in the Zr/Hf ratio in the evolution of the ultramafic-alkali magmatic system due to a higher distribution coefficient of Hf in pyroxene with respect to Zr. The Rayleigh equation was used to calculate a quantitative model of variation in the Zr/Hf ratio in the development of the Guli magmatic system. Alkali carbonatite rocks originated from rare element-rich mantle reservoirs, in particular, the metasomatized mantle. Carbonated mantle xenoliths are characterized by a high Zr/Hf ratio due to clinopyroxene development during metasomatic replacement of orthopyroxene by carbonate fluid melt.

Meteoritic trace element toxification and the terminal Mesozoic mass extinction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dickson, S.M.; Erickson, D.J. III

1985-01-01

Calculations of trace element fluxes to the earth associated with 5 and 10 kilometer diameter Cl chondrites and iron meteorites are presented. The data indicate that the masses of certain trace elements contained in the bolide, such as Fe, Co, Ni, Cr, Pb, and Cu, are as large as or larger than the world ocean burden. The authors believe that this pulse of trace elements was of sufficient magnitude to perturb the biogeochemical cycles operative 65 million years ago, a probably time of meteorite impact. Geochemical anomalies in Cretaceous-Tertiary boundary sediments suggest that elevated concentrations of trace elements may havemore » persisted for thousands of years in the ocean. Through direct exposure and bioaccumulation, many trophic levels of the global food chain, including that of the dinosaurs, would have been adversely affected by these meteoritic trace elements. The trace element toxification hypothesis may account for the selective extinction of both marine and terrestrial species in the enigmatic terminal Mesozoic event.« less

Petrography and geochemistry of Jurassic sandstones from the Jhuran Formation of Jara dome, Kachchh basin, India: Implications for provenance and tectonic setting

NASA Astrophysics Data System (ADS)

Periasamy, V.; Venkateshwarlu, M.

2017-06-01

Sandstones of Jhuran Formation from Jara dome, western Kachchh, Gujarat, India were studied for major, trace and rare earth element (REE) geochemistry to deduce their paleo-weathering, tectonic setting, source rock characteristics and provenance. Petrographic analysis shows that sandstones are having quartz grains with minor amount of K-feldspar and lithic fragments in the modal ratio of Q 89:F 7:L 4. On the basis of geochemical results, sandstones are classified into arkose, sub-litharenite, wacke and quartz arenite. The corrected CIA values indicate that the weathering at source region was moderate to intense. The distribution of major and REE elements in the samples normalized to upper continental crust (UCC) and chondrite values indicate similar pattern of UCC. The tectonic discrimination diagram based on the elemental concentrations and elemental ratios of Fe2O3 + MgO vs. TiO2, SiO2 vs. log(K2O/Na2O), Sc/Cr vs. La/Y, Th-Sc-Zr/10, La-Th-Sc plots Jhuran Formation samples in continental rift and collision settings. The plots of Ni against TiO2, La/Sc vs. Th/Co and V-Ni-Th ∗10 reveals that the sediments of Jhuran Formation were derived from felsic rock sources. Additionally, the diagram of (Gd/Yb) N against Eu/Eu ∗ suggest the post-Archean provenance as source possibly Nagar Parkar complex for the studied samples.

Trace elemental analysis of human breast cancerous blood by advanced PC-WDXRF technique

NASA Astrophysics Data System (ADS)

Singh, Ranjit; Kainth, Harpreet Singh; Prasher, Puneet; Singh, Tejbir

2018-03-01

The objective of this work is to quantify the trace elements of healthy and non-healthy blood samples by using advanced polychromatic source based wavelength dispersive X-ray fluorescence (PC-WDXRF) technique. The imbalances in trace elements present in the human blood directly or indirectly lead to the carcinogenic process. The trace elements 11Na, 12Mg, 15P, 16S, 17Cl, 19K, 20Ca, 26Fe, 29Cu and 30Zn are identified and their concentrations are estimated. The experimental results clearly discuss the variation and role of various trace elements present in the non-healthy blood samples relative to the healthy blood samples. These results establish future guidelines to probe the possible roles of essential trace elements in the breast carcinogenic processes. The instrumental sensitivity and detection limits for measuring the elements in the atomic range 11 ≤ Z ≤ 30 have also been discussed in the present work.

INAA Application for Trace Element Determination in Biological Reference Material

NASA Astrophysics Data System (ADS)

Atmodjo, D. P. D.; Kurniawati, S.; Lestiani, D. D.; Adventini, N.

2017-06-01

Trace element determination in biological samples is often used in the study of health and toxicology. Determination change to its essentiality and toxicity of trace element require an accurate determination method, which implies that a good Quality Control (QC) procedure should be performed. In this study, QC for trace element determination in biological samples was applied by analyzing the Standard Reference Material (SRM) Bovine muscle 8414 NIST using Instrumental Neutron Activation Analysis (INAA). Three selected trace element such as Fe, Zn, and Se were determined. Accuracy of the elements showed as %recovery and precision as %coefficient of variance (%CV). The result showed that %recovery of Fe, Zn, and Se were in the range between 99.4-107%, 92.7-103%, and 91.9-112%, respectively, whereas %CV were 2.92, 3.70, and 5.37%, respectively. These results showed that INAA method is precise and accurate for trace element determination in biological matrices.

Correlative characterization of primary Al{sub 3}(Sc,Zr) phase in an Al–Zn–Mg based alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, J.H., E-mail: jie-hua.li@hotmail.com; Wiessner, M.; Albu, M.

2015-04-15

Three-dimensional electron backscatter diffraction, focused ion beam, transmission electron microscopy and energy filtered transmission electron microscopy were employed to investigate the structural information of primary Al{sub 3}(Sc,Zr) phase, i.e. size, shape, element distribution and orientation relationship with the α-Al matrix. It was found that (i) most primary Al{sub 3}(Sc,Zr) phases have a cubic three-dimensional morphology, with a size of about 6–10 μm, (ii) most primary Al{sub 3}(Sc,Zr) phases are located within the α-Al matrix, and exhibit a cube to cube orientation relationship with the α-Al matrix, and (iii) a layer by layer growth was observed within primary Al{sub 3}(Sc,Zr) phases.more » Al, Cu, Si and Fe are enriched in the α-Al matrix between the layers of cellular eutectic Al{sub 3}(Sc,Zr) phase, while Sc, Ti and Zr are enriched in small Al{sub 3}(Sc,Zr) phases. A peritectic reaction and subsequent eutectic reaction between Al{sub 3}Sc and Al was proposed to interpret the observed layer by layer growth. This paper demonstrates that the presence of impurities (Fe, Si, Cu, Ti) in the diffusion field surrounding the growing Al{sub 3}(Sc,Zr) particle enhances the heterogeneous nucleation of Al{sub 3}(Sc,Zr) phases. - Highlights: • Most fine cubic primary Al{sub 3}(Sc,Zr) phases were observed within the α-Al matrix. • A layer by layer growth within primary Al{sub 3}(Sc,Zr) phase was observed. • A peritectic and subsequent eutectic reaction between Al{sub 3}Sc and Al was proposed. • Impurities in diffusion fields enhance heterogeneous nucleation of Al{sub 3}(Sc,Zr)« less

Fabrication of novel metal ion imprinted xanthan gum-layered double hydroxide nanocomposite for adsorption of rare earth elements.

PubMed

Iftekhar, Sidra; Srivastava, Varsha; Hammouda, Samia Ben; Sillanpää, Mika

2018-08-15

The work focus to enhance the properties of xanthan gum (XG) by anchoring metal ions (Fe, Zr) and encapsulating inorganic matrix (M@XG-ZA). The fabricated nanocomposite was characterized by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), surface area (BET) and zeta potential analysis. The adsorption of Sc, Nd, Tm and Yb was investigated after screening of synthesized materials in detail to understand the influence of pH, contact time, temperature and initial REE (rare earth element) concentration both in single and multicomponent system via batch adsorption. The adsorption mechanism was verified by FTIR, SEM and elemental mapping. The SEM images of Zr@XG-ZA demonstrate scutes structure, which disappeared after adsorption of REEs. The maximum adsorption capacities were 132.30, 14.01, 18.15 and 25.73 mg/g for Sc, Nd, Tm and Yb, respectively. The adsorption efficiency over Zr@XG-ZA in multicomponent system was higher than single system and the REEs followed the order: Sc > Yb > Tm > Nd. The Zr@XG-ZA demonstrate good adsorption behavior for REEs up to five cycles and then it can be used as photocatalyst for the degradation of tetracycline. Thus, the work adds a new insight to design and preparation of efficient bifunctional adsorbents from sustainable materials for water purification. Copyright © 2018 Elsevier Ltd. All rights reserved.

Isoelectronic substitutions and aluminium alloying in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor

NASA Astrophysics Data System (ADS)

von Rohr, Fabian O.; Cava, Robert J.

2018-03-01

High-entropy alloys (HEAs) are a new class of materials constructed from multiple principal elements statistically arranged on simple crystallographic lattices. Due to the large amount of disorder present, they are excellent model systems for investigating the properties of materials intermediate between crystalline and amorphous states. Here we report the effects of systematic isoelectronic replacements, using Mo-Y, Mo-Sc, and Cr-Sc mixtures, for the valence electron count 4 and 5 elements in the body-centered cubic (BCC) Ta-Nb-Zr-Hf-Ti high-entropy alloy (HEA) superconductor. We find that the superconducting transition temperature Tc strongly depends on the elemental makeup of the alloy, and not exclusively its electron count. The replacement of niobium or tantalum by an isoelectronic mixture lowers the transition temperature by more than 60%, while the isoelectronic replacement of hafnium, zirconium, or titanium has a limited impact on Tc. We further explore the alloying of aluminium into the nearly optimal electron count [TaNb] 0.67(ZrHfTi) 0.33 HEA superconductor. The electron count dependence of the superconducting Tc for (HEA)Al x is found to be more crystallinelike than for the [TaNb] 1 -x(ZrHfTi) x HEA solid solution. For an aluminum content of x =0.4 the high-entropy stabilization of the simple BCC lattice breaks down. This material crystallizes in the tetragonal β -uranium structure type and superconductivity is not observed above 1.8 K.

New insights into trace element wet deposition in the Himalayas: amounts, seasonal patterns, and implications.

PubMed

Cong, Zhiyuan; Kang, Shichang; Zhang, Yulan; Gao, Shaopeng; Wang, Zhongyan; Liu, Bin; Wan, Xin

2015-02-01

Our research provides the first complete year-long dataset of wet deposition of trace elements in the high Himalayas based on a total of 42 wet deposition events on the northern slope of Mt. Qomolangma (Everest). Except for typical crustal elements (Al, Fe, and Mn), the concentration level of most trace elements (Sc, V, Cr, Co, Ni, Cu, Zn, As, Mo, Cd, Sn, Cs, Pb, Bi, and U) are generally comparable to those preserved in snow pits and ice cores from the nearby East Rongbuk Glacier. Cadmium was the element most affected by anthropogenic emissions. No pronounced seasonal variations are observed for most trace elements despite different transport pathways. In our study, the composition of wet precipitation reflects a regional background condition and is not clearly related to specific source regions. For the trace element record from ice cores and snow pits in the Himalayas, it could be deduced that the pronounced seasonal patterns were caused by the dry deposition of trace elements (aerosols) during their long exposure to the atmosphere after precipitation events. Our findings are of value for the understanding of the trace element deposition mechanisms in the Himalayas.

Chemical evolution of a pleistocene rhyolitic center: Sierra La Primavera, Jalisco, México

NASA Astrophysics Data System (ADS)

Mahood, Gail A.

1981-06-01

The late Pleistocene caldera complex of the Sierra La Primavera, Jalisco, México, contains well-exposed lava flows and domes, ash-flow tuff, air-fall pumice, and caldera-lake sediments. All eruptive units are high-silica rhyolites, but systematic chemical differences correlate with age and eruptive mode. The caldera-producing unit, the 45-km3 Tala Tuff, is zoned from a mildly peralkaline first-erupted portion enriched in Na, Rb, Cs, Cl, F, Zn, Y, Zr, Hf, Ta, Nb, Sb, HREE, Pb, Th, and U to a metaluminous last-erupted part enriched in K, LREE, Sc, and Ti; Al, Ca, Mg, Mn, Fe, and Eu are constant within analytical errors. The earliest post-caldera lava, the south-central dome, is nearly identical to the last-erupted portion of the Tala Tuff, whereas the slightly younger north-central dome is chemically transitional from the south-central dome to later, moremafic, ring domes. This sequence of ash-flow tuff and domes represents the tapping of progressively deeper levels of a zoned magma chamber 95,000 ± 5,000 years ago. Since that time, the lavas that erupted 75,000, 60,000, and 30,000 years ago have become decreasingly peralkaline and progressively enriched only in Si, Rb, Cs, and possibly U. They represent successive eruption of the uppermost magma in the post-95,000-year magma chamber. Eruptive units of La Primavera are either aphyric or contain up to 15% phenocrysts of sodic sanidine ≧quartz >ferrohedenbergite >fayalite>ilmenite±titanomagnetite. Whereas major-element compositions of sanidine, clinopyroxene, and fayalite phenocrysts changed only slightly between eruptive groups, concentrations of many trace elements changed by factors of 5 to 10, resulting in crystal/glass partition coefficients that differ by factors of up to 20 between successively erupted units. The extreme variations in partitioning behavior are attributed to small changes in bulk composition of the melt because major-element compositions of the phenocrysts and temperature, pressure, and oxygen fugacity of the magma all remained essentially constant. Crystal settling and incremental partial melting by themselves appear incapable of producing either the chemical gradients within the Tala Tuff magma chamber or the trends with time in the post-caldera lavas. Transport of trace metals as volatile complexes within the thermal and gravitational gradient in volatilerich but water-undersaturated magma is considered the dominant process responsible for compositional zonation in the Tala Tuff. The evolution of the post-caldera lavas with time is thought to involve the diffusive emigration of trace elements from a relatively dry magma as a decreasing proportion of network modifiers and/or a decreasing concentration of complexing ligands progressively reduced trace-metal-site availability in the silicate melt.

Mineralogical and geochemical features of the coarse saprolite developed on orthogneiss in the SW of Yaoundé, South Cameroon

NASA Astrophysics Data System (ADS)

Ndjigui, P.-D.; Badinane, M. F. B.; Nyeck, B.; Nandjip, H. P. K.; Bilong, P.

2013-03-01

A petrological investigation was performed in the coarse saprolite on orthogneiss in Yaoundé (South Cameroon) using combined whole rock geochemical (XRF, ICP-MS) and mineralogical (XRD, SEM) techniques. The orthogneiss has high contents in SiO2 (61.56 wt.%), Ba (916 ppm) and REE (209 ppm), moderate content in Al2O3 (14.34 wt.%) and negative Eu anomaly (Eu/Eu* = 0.68). The weathering leads to the formation of three main constituents in the coarse saprolite: (i) the loose materials (∼85 vol.%) are basically clayey silty with relic structure. They are composed of kaolinite, quartz and goethite. The loose materials have high contents in SiO2 (56-64.83 wt.%) and Al2O3 (21.48-23.96 wt.%), and moderate contents in V (163-236 ppm), Ba (95-340 ppm) and Zr (160-313 ppm). The REE content is low (∼49-169 ppm) relative to the parent rock with LREE-enrichment (LREE/HREE ∼ 7-17). Positive Ce anomaly (Ce/Ce* ∼ 3.35) is observed in the white veins and slight positive Eu anomalies (Eu/Eu* ∼ 1.2-1.4) are noted in all loose samples. The (La/Yb)N ratios (∼0.8-1.5) indicate high REE-fractionation. The mass balance calculation reveals the depletion of several elements except Al, Ti, Sc, Y, Th, Sb and Hf; (ii) the iron duricrust (∼10 vol.%) is located at the bottom and the top of the horizon. The mineral assemblage is dominated by hematite and goethite. The upper iron duricrust has high contents in Fe2O3 (45.60 wt.%) and Cr (1641 ppm), moderate contents in V (459 ppm) and Zn (143 ppm), and low REE content (47 ppm) with low LREE/HREE ratio (4.28). The upper iron duricrust is more enriched in Fe2O3 (53.26 wt.%) than the lower one. Vanadium, Cr and Zr have high contents relative to other trace elements. The REE content is low (39 ppm) as well as the LREE/HREE ratio (2.94). The iron duricrust has negative Ce anomalies (Ce/Ce* ∼ 0.66-0.69) and very low (La/Yb)N ratios (0.1-0.3). Several elements reported in the iron duricrust are highly leached except Fe, Cr, Zn, Sc, V, Pb, Zr, Cu and Th; and (iii) the Mn-rich materials (<5 vol.%) are made up of birnessite, cryptomelane, and low quantities of quartz, kaolinite and goethite. The SEM investigation reveals that Ba and Pb are linked in Mn-bearing phases and Ce-oxides appear as fine-grained intergrowth between Mn-bearing phases. The Mn-bearing phases are enriched in MnO (33.86 wt.%), BaO (4.30 wt.%), Co (1716 ppm), Pb (1315 ppm) and Ce (5202 ppm). Positive Ce and Eu anomalies are observed (Ce/Ce* ∼ 15.60 and Eu/Eu* ∼ 2). The mass balance calculations indicate the strong accumulation of Mn, Ni, Co, Zn, Sc, Cu, Ba, Pb, Y, Ga, Zr and REE. The Mn-bearing phases might be derived from the accumulation of silicate residues and Mn within the parent rock. The transition from the parent rock to the coarse saprolite is marked by high leaching of several elements.

The Chemical Structure of the Hawaiian Mantle Plume

NASA Astrophysics Data System (ADS)

Ren, Z.; Hirano, N.; Hirata, T.; Takahashi, E.; Ingle, S.

2004-12-01

Numerous geochemical studies of Hawaiian basaltic lavas have shown that the Hawaiian mantle plume is isotopically heterogeneous. However, the distribution and scale of these heterogeneities remain unknown. This is essentially due to the complex interactions created by melting a heterogeneous source, subsequent aggregation of the melts on their way to the surface, and mixing that takes place in shallow magma chambers prior to eruption. In sum, the measured compositions of bulk lavas may represent only _eaverage_f compositions that do not fully reflect the complexity of either the mantle source heterogeneity and/or chemical structure. Melt inclusions, or samples of the local magma frozen in olivine phenocrysts during their formation, are better at recording the complex magmatic history than are the bulk samples. Here, we report major and trace element compositions of olivine-hosted melt inclusions from submarine Haleakala lavas that were collected by 2001-2002 JAMSTEC cruises measured by EPMA and LA-ICP-MS after homogenization at 1250° C, QFM for 20min. Melt inclusions from the submarine Hana Ridge (Haleakala volcano) show large ranges in CaO/Al2O3 (0.92-1.50), TiO2/Na2O (0.79-1.60) and Sr/Nb (14.56-36.60), Zr/Nb (6.48-16.95), ranging from Kilauea-like to Mauna Loa-like compositions within separately-sampled lavas as well as in a single host lava sample. Bulk rocks geochemistry shows that major element composition and trace element ratios such as Zr/Nb, Sr/Nb (Ren et al., 2004a, in press, J. Petrol.) together with Pb, Nd and Sr isotopic ratios (Ren et al., 2004b, submitted to J. Petrol.) of Haleakala shield volcano also display systematic compositional variation changing from a Kilauea-like in the submarine Hana Ridge (main shield stage) to Kilauea-Mauna Loa-like in the subaerial Honomanu stage (late shield stage, data from Chen and Frey, 1991). Some of the compositional variations in melt inclusions in single rocks are wider range than over-all variation observed in bulk rocks. It is important that both Kilauea-like and Mauna Loa-like compositions co-exist in melt inclusions in single submarine Hana Ridge rocks which are identified as Kilauea-like based on bulk geochemistry. These observations are inconsistent with the current interpretation that magma compositions are controlled by concentric zonation of the Hawaiian mantle plume (e.g. Kea component and Loa component), manifested as the Kea trend and the Loa trend volcanoes (e.g. Hauri, 1996; Lassiter et al., 1996). Our new data from olivine-hosted melt inclusions imply that the chemical structure of the Hawaiian mantle plume is significantly more complicated than previously modeled and the length-scale of chemical heterogeneity must be remarkably smaller than estimated based on bulk rock geochemistry.

Actinides in metallic waste from electrometallurgical treatment of spent nuclear fuel

NASA Astrophysics Data System (ADS)

Janney, D. E.; Keiser, D. D.

2003-09-01

Argonne National Laboratory has developed a pyroprocessing-based technique for conditioning spent sodium-bonded nuclear-reactor fuel in preparation for long-term disposal. The technique produces a metallic waste form whose nominal composition is stainless steel with 15 wt.% Zr (SS-15Zr), up to ˜ 11 wt.% actinide elements (primarily uranium), and a few percent metallic fission products. Actual and simulated waste forms show similar eutectic microstructures with approximately equal proportions of iron solid solution phases and Fe-Zr intermetallics. This article reports on an analysis of simulated waste forms containing uranium, neptunium, and plutonium.

Fractionation of Zr and Hf during the differentiation of peralkaline magmatic system (Lovozero rare metal deposit, Kola Peninsula)

NASA Astrophysics Data System (ADS)

Kogarko, Liya

2016-04-01

Zirconium and hafnium are valuable strategic metals. We assessed principal features of the distribution of these elements in peralkaline rocks, ores and rock-forming and accessory minerals of Lovozero complex. The accumulation of these elements during the evolution of alkaline magma of Lovozero deposit up to extremely high concentrations in eudialyte ores (5-8% ZrO2 and 1200-1800 ppm Hf) has been established. These ores represent valuable complex raw material not only for Zr and Hf, but for REE as well. We evaluated partition coefficients of these elements in alkaline pyroxenes (aegirines) from porphyry-like agpaitic lujavrites of Lovozero massif which are 0.40 for zirconium and 0.58 for hafnium. We assessed variations of Zr/Hf ratio for all the rocks of Lovozero alkaline massif. The growth of this ratio in the course of the evolution of alkaline magma has been observed from 38 in the earliest magmatic phase, to 44 in the second phase and to 51-53 in the latest manifestation of alkaline magmatsm. On the basis of the obtained data and equations of equilibrium and fractional crystallization the model of the fractionation of zirconium and hafnium during the evolution of Lovozero intrusion has been constructed. We have demonstrated that the source of strongly enriched magmatic systems similar to Lovozero rare metal deposit is short-lived enriched reservoir - metasomatized and carbonatized mantle substrate. We investigated the fractionation of zirconium and hafnium in carbonatized mantle xenoliths from East Antarctica. The elevated Zr/Hf ratios (up to 125) in metasomatized xenoliths by comparison with the chondritic value have been found. The main reactions of carbonate metasomatism lead to the replacement of primary orthopyroxene by clinopyroxene 2Mg2Si2O6 + CaMg(CO3)2 = 2Mg2SiO4 + CaMgSi2O6 + 2CO2 3CaMg(CO3)2 + CaMgSi2O6 = 4CaCO3 + 2Mg2SiO4 + 2CO2 The substantial expansion of the clinopyroxene crystallization field results in increase of Zr/Hf ratio in equilibrium melt due to the higher value of Hf partition coefficient by comparison with Zr. The migration of active carbonate and carbonate-silicate melts equilibrated with the metasomatic wehrlites leads to the increase in Zr/Hf ratio in carbonatized mantle substrate. This work has been financially supported by the grant 15-17-30019 of the Russian Science Foundation.

Data evaluation of trace elements determined in Nigerian coal using cluster procedures.

PubMed

Ewa, I O B

2004-05-01

Large data-sets of elements determined by instrumental neutron activation analysis (INAA) require meaningful interpretation in order to determine the pattern of their existence in host matrices. This could be achieved using cluster procedures. Element abundances (Al, As, Ba, Br, Ca, Ce, Cs, Dy, Eu, Fe, Ga, Gd, Hf, K, La, Lu, Mg, Mn, Na, O, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, Ti, U, V, Yb, Zn and Zr) of prepared and run-of-mine coals from eight principal mines (Onyeama, Ogbete, Enugu, Gombe, Asaba-Ugwashi, Okaba, Afikpo and Lafia ) in Nigeria were determined by INAA. Quality control of the measurements was assured by the re-determination of a standard reference material, NIST 1632a. These data-sets were then tested for multi-variate statistics using METHOD = SINGLE in the cluster procedure. The computer-assisted package SAS was used to generate the dendrograms while the algorithm used was stored Euclidean distances. The results showed a recognition pattern, useful for the interpretation of coalification histories and the prediction of fuel ranking for Nigerian coals. High segregation of coal fly ash was observed, while metallurgical coal grouped together with high-ranking coals of Okaba, Enugu and Obi (Lafia). Further work revealed some of these coals as having high gross calorific value (7908 kcal kg(-1) for Enugu coal; 7200 kcal kg(-1) for Okaba) and low sulphur thereby making them efficient fuel materials.

Plate tectonics and continental basaltic geochemistry throughout Earth history

NASA Astrophysics Data System (ADS)

Keller, Brenhin; Schoene, Blair

2018-01-01

Basaltic magmas constitute the primary mass flux from Earth's mantle to its crust, carrying information about the conditions of mantle melting through which they were generated. As such, changes in the average basaltic geochemistry through time reflect changes in underlying parameters such as mantle potential temperature and the geodynamic setting of mantle melting. However, sampling bias, preservation bias, and geological heterogeneity complicate the calculation of representative average compositions. Here we use weighted bootstrap resampling to minimize sampling bias over the heterogeneous rock record and obtain maximally representative average basaltic compositions through time. Over the approximately 4 Ga of the continental rock record, the average composition of preserved continental basalts has evolved along a generally continuous trajectory, with decreasing compatible element concentrations and increasing incompatible element concentrations, punctuated by a comparatively rapid transition in some variables such as La/Yb ratios and Zr, Nb, and Ti abundances approximately 2.5 Ga ago. Geochemical modeling of mantle melting systematics and trace element partitioning suggests that these observations can be explained by discontinuous changes in the mineralogy of mantle partial melting driven by a gradual decrease in mantle potential temperature, without appealing to any change in tectonic process. This interpretation is supported by the geochemical record of slab fluid input to continental basalts, which indicates no long-term change in the global proportion of arc versus non-arc basaltic magmatism at any time in the preserved rock record.

Chemical Abundances of Two Stars in the Large Magellanic Cloud Globular Cluster NGC 1718

NASA Astrophysics Data System (ADS)

Sakari, Charli M.; McWilliam, Andrew; Wallerstein, George

2017-05-01

Detailed chemical abundances of two stars in the intermediate-age Large Magellanic Cloud (LMC) globular cluster NGC 1718 are presented, based on high-resolution spectroscopic observations with the MIKE spectrograph. The detailed abundances confirm NGC 1718 to be a fairly metal-rich cluster, with an average [Fe/H] ˜ -0.55 ± 0.01. The two red giants appear to have primordial O, Na, Mg and Al abundances, with no convincing signs of a composition difference between the two stars - hence, based on these two stars, NGC 1718 shows no evidence for hosting multiple populations. The Mg abundance is lower than Milky Way field stars, but is similar to LMC field stars at the same metallicity. The previous claims of very low [Mg/Fe] in NGC 1718 are therefore not supported in this study. Other abundances (Si, Ca, Ti, V, Mn, Ni, Cu, Rb, Y, Zr, La and Eu) all follow the LMC field star trend, demonstrating yet again that (for most elements) globular clusters trace the abundances of their host galaxy's field stars. Similar to the field stars, NGC 1718 is found to be mildly deficient in explosive α-elements, but moderately to strongly deficient in O, Na, Mg, Al and Cu, elements that form during hydrostatic burning in massive stars. NGC 1718 is also enhanced in La, suggesting that it was enriched in ejecta from metal-poor asymptotic giant branch stars.

The effect of tissue structure and soil chemistry on trace element uptake in fossils

NASA Astrophysics Data System (ADS)

Hinz, Emily A.; Kohn, Matthew J.

2010-06-01

Trace element profiles for common divalent cations (Sr, Zn, Ba), rare-earth elements (REE), Y, U, and Th were measured in fossil bones and teeth from the c. 25 ka Merrell locality, Montana, USA, by using laser-ablation ICP-MS. Multiple traverses in teeth were transformed into 2-D trace element maps for visualizing structural influences on trace element uptake. Trace element compositions of different soils from the fossil site were also analyzed by solution ICP-MS, employing progressive leaches that included distilled H 2O, 0.1 M acetic acid, and microwave digestion in concentrated HCl-HNO 3. In teeth, trace element uptake in enamel is 2-4 orders of magnitude slower than in dentine, forming an effective trace element barrier. Uptake in dentine parallel to the dentine-enamel interface is enhanced by at least 2 orders of magnitude compared to transverse, causing trace element "plumes" down the tooth core. In bone, U, Ba and Sr are nearly homogeneous, implying diffusivities ˜5 orders of magnitude faster than in enamel and virtually complete equilibration with host soils. In contrast all REE show strong depletions inward, with stepwise linear segments in log-normal or inverse complementary error function plots; these data require a multi-medium diffusion model, with about 2 orders of magnitude difference in slowest vs. fastest diffusivities. Differences in REE diffusivities in bone (slow) vs. dentine (fast) reflect different partition coefficients ( Kd's). Although acid leaches and bulk digestion of soils yield comparable fossil-soil Kd's among different elements, natural solutions are expected to be neutral to slightly basic. Distilled H 2O leachates instead reveal radically different Kd's in bone for REE than for U-Sr-Ba, suggest orders of magnitude lower effective diffusivities for REE, and readily explain steep vs. flat profiles for REE vs. U-Sr-Ba, respectively. Differences among REE Kd's and diffusivities may explain inward changes in Ce anomalies. Acid washes and bulk soil compositions yield misleading Kd's for many trace elements, especially the REE, and H 2O-leaches are preferred. Patterns of trace element distributions indicate diagenetic alteration at all scales, including enamel, and challenge the use of trace elements in paleodietary studies.

A Global Overview of Exposure Levels and Biological Effects of Trace Elements in Penguins.

PubMed

Espejo, Winfred; Celis, José E; GonzÃlez-Acuña, Daniel; Banegas, Andiranel; Barra, Ricardo; Chiang, Gustavo

2018-01-01

Trace elements are chemical contaminants that can be present almost anywhere on the planet. The study of trace elements in biotic matrices is a topic of great relevance for the implications that it can have on wildlife and human health. Penguins are very useful, since they live exclusively in the Southern Hemisphere and represent about 90% of the biomass of birds of the Southern Ocean. The levels of trace elements (dry weight) in different biotic matrices of penguins were reviewed here. Maps of trace element records in penguins were included. Data on exposure and effects of trace elements in penguins were collected from the literature. The most reported trace elements in penguins are aluminum, arsenic, cadmium, lead, mercury, copper, zinc, and manganese. Trace elements have been measured in 11 of the 18 species of penguins. The most studied biotic matrices are feathers and excreta. Most of the studies have been performed in Antarctica and subantarctic Islands. Little is known about the interaction among metals, which could provide better knowledge about certain mechanisms of detoxification in penguins. Future studies of trace elements in penguins must incorporate other metals such as vanadium, cobalt, nickel, and chromium. Data of metals in the species such as Eudyptes pachyrhynchus, Eudyptes moseleyi, Eudyptes sclateri, Eudyptes robustus, Eudyptes schlegeli, Spheniscus demersus, Spheniscus mendiculus, and Megadyptes antipodes are urged. It is important to correlate levels of metals in different biotic matrices with the effects on different species and in different geographic locations.

Trace element supplementation in the biogas production from wheat stillage--optimization of metal dosing.

PubMed

Schmidt, Thomas; Nelles, Michael; Scholwin, Frank; Pröter, Jürgen

2014-09-01

A trace element dosing strategy for the anaerobic digestion of wheat stillage was developed in this study. Mesophilic CSTR reactors were operated with the sulfuric substrate wheat stillage in some cases under trace element deficiency. After supplementing trace elements during the start-up, one of the elements of Fe, Ni, Co, Mo, and W were depleted in one digester while still augmenting the other elements to determine minimum requirements for each element. The depletion of Fe and Ni resulted in a rapid accumulation of volatile fatty acids while Co and W seem to have a long-term effect. Based on the results it was possible to reduce the dosing of trace elements, which is positive with reference to economic and environmental aspects. Copyright © 2014 Elsevier Ltd. All rights reserved.

Structural and Mechanical Properties of the ZrC/Ni-Nanodiamond Coating Synthesized by the PVD and Electroplating Processes for the Cutting Knifes

NASA Astrophysics Data System (ADS)

Chayeuski, V.; Zhylinski, V.; Cernashejus, O.; Visniakov, N.; Mikalauskas, G.

2018-04-01

In this work, combined gradient ZrC/Ni-nanodiamond ultradispersed diamonds (UDD) coatings were synthesized on the surface of knife blades made of hard alloy WC-2 wt.% Co by electroplating and cathode arc evaporation PVD techniques to increase the durability period of a wood-cutting milling tool. The microstructure, phase and elemental composition, microhardness, and adhesion strength of the coatings were investigated. Ni-UDD layer is not mixed with the ZrC coating and hard alloy substrate. Cobalt is present in Ni-UDD layer after deposition of ZrC. The ZrC/Ni-nanodiamond coating consists of separate phases of zirconium carbide (ZrC), α-Ni, and Ni-UDD. The maximum value of microhardness of the Ni-nanodiamond coating is 5.9 GPa. The microhardness value of the ZrC/Ni-nanodiamond coatings is 25 ± 6 GPa, which corresponds to the microhardness of the hard alloy substrate and ZrC coating. The obtained high values of the critical loads on the scratch track of the ZrC/Ni-nanodiamond coating in 24 N prove a sufficiently high value of the adhesion strength of the bottom Ni-UDD layer with WC-Co substrate. Pilot testing of ZrC/Ni-nanodiamond-coated cutting tools proved their increasing durability period to be 1.5-1.6 times higher than that of bare tools, when milling laminated chipboard.

Zirconium Ions Up-Regulate the BMP/SMAD Signaling Pathway and Promote the Proliferation and Differentiation of Human Osteoblasts

PubMed Central

Chen, Yongjuan; Roohani-Esfahani, Seyed-Iman; Lu, ZuFu; Zreiqat, Hala; Dunstan, Colin R.

2015-01-01

Zirconium (Zr) is an element commonly used in dental and orthopedic implants either as zirconia (ZrO2) or in metal alloys. It can also be incorporated into calcium silicate-based ceramics. However, the effects of in vitro culture of human osteoblasts (HOBs) with soluble ionic forms of Zr have not been determined. In this study, primary culture of human osteoblasts was conducted in the presence of medium containing either ZrCl4 or Zirconium (IV) oxynitrate (ZrO(NO3)2) at concentrations of 0, 5, 50 and 500 µM, and osteoblast proliferation, differentiation and calcium deposition were assessed. Incubation of human osteoblast cultures with Zr ions increased the proliferation of human osteoblasts and also gene expression of genetic markers of osteoblast differentiation. In 21 and 28 day cultures, Zr ions at concentrations of 50 and 500 µM increased the deposition of calcium phosphate. In addition, the gene expression of BMP2 and BMP receptors was increased in response to culture with Zr ions and this was associated with increased phosphorylation of SMAD1/5. Moreover, Noggin suppressed osteogenic gene expression in HOBs co-treated with Zr ions. In conclusion, Zr ions appear able to induce both the proliferation and the differentiation of primary human osteoblasts. This is associated with up-regulation of BMP2 expression and activation of BMP signaling suggesting this action is, at least in part, mediated by BMP signaling. PMID:25602473

Enrichment Of Volcanogenic Trace Elements, Co, Cr, Cu, Ni, Mo And Zr In A Continuous Subsurface Eagle Ford Core In South Texas And Origin Of The Oceanic Anoxic Event II At The Cenomanian-Turonian (C/T) Boundary

NASA Astrophysics Data System (ADS)

Valencia, D.; Basu, A. R.; Loocke, M. P.

2017-12-01

The Eagle Ford Formation containing the Cenomanian-Turonian (C/T) boundary continues to be studied globally not only for its economic potential and analog for `frack-able' unconventional organic-rich formations, but it is of particular interest to researchers because it was deposited across the C/T boundary recording an Oceanic Anoxic Event (OAE2). OAEs are short lived episodes (< 1Ma) of widespread marine anoxia during which large amounts of organic carbon were buried on the ocean floor under oxygen-deficient bottom waters. The exact trigger for the increased deposition of organic matter into the sedimentary record remains enigmatic. Geochemical and geochronological analysis of a subsurface 300ft long continuous core of the Eagle Ford Formation of South Texas shows evidence for volcanism throughout. This is confirmed by multiple thin intermittent bentonite beds. The whole rock black shale (marl) shows elevated concentrations of volcanogenic trace elements (Co, Cr, Cu, Ni, Mo and Zn) throughout the core. By sampling bentonite bed zircons near the inferred C/T boundary, U-Pb age of 93.2 ±1.7 Ma for the Eagle Ford is established. Using this horizon, the onset of OAE2 is constrained and well-correlated with the positive δ13C excursion. For the trace element analysis, the core was sampled at 10ft intervals for ICP-MS. The analytical results show significantly increased volcanogenic trace metal input correlating with increased Total Organic Carbon and positive δ13C values at the C/T dated zircon horizon. OAE2, defined by the positive δ13C excursion, was found to span over an interval of 85ft. With a definitive constraint for OAE2 established, this well-defined interval was analyzed at a much higher resolution using ED-XRF. The core was then sampled at 6' intervals throughout the C/T boundary at OAE2. The high-resolution sampling of the core shows 80-99% increase in abundance of Co, Cr, Cu, Ni, Mo, Zn over the average Post Australian Archean Shale(PAAS), representative of average continental crust. These volcanogenic-rich intervals reach peak values before the onset of OAE2 and at the maximum values for the positive δ13C isotope excursion directly after the 93.2 ±1.7 Ma bentonite bed. This continuous vertical extent of data set supports volcanic origin resulted in organic matter deposition and subsequent anoxia.

Loess as an environmental archive of atmospheric trace element deposition

NASA Astrophysics Data System (ADS)

Blazina, T.; Winkel, L. H.

2013-12-01

Environmental archives such as ice cores, lake sediment cores, and peat cores have been used extensively to reconstruct past atmospheric deposition of trace elements. These records have provided information about how anthropogenic activities such as mining and fossil fuel combustion have disturbed the natural cycles of various atmospherically transported trace elements (e.g. Pb, Hg and Se). While these records are invaluable for tracing human impacts on such trace elements, they often provide limited information about the long term natural cycles of these elements. An assumption of these records is that the observed variations in trace element input, prior to any assumed anthropogenic perturbations, represent the full range of natural variations. However, records such as those mentioned above which extend back to a maximum of ~400kyr may not capture the potentially large variations of trace element input occurring over millions of years. Windblown loess sediments, often representing atmospheric deposition over time scales >1Ma, are the most widely distributed terrestrial sediments on Earth. These deposits have been used extensively to reconstruct continental climate variability throughout the Quaternary and late Neogene periods. In addition to being a valuable record of continental climate change, loess deposits may represent a long term environmental archive of atmospheric trace element deposition and may be combined with paleoclimate records to elucidate how fluctuations in climate have impacted the natural cycle of such elements. Our research uses the loess-paleosol deposits on the Chinese Loess Plateau (CLP) to quantify how atmospheric deposition of trace elements has fluctuated in central China over the past 6.8Ma. The CLP has been used extensively to reconstruct past changes of East Asian monsoon system (EAM). We present a suite of trace element concentration records (e.g. Pb, Hg, and Se) from the CLP which exemplifies how loess deposits can be used as an environmental archive to reconstruct long term natural variations in atmospheric trace element input. By comparing paleomonsoon proxy data with geochemical data we can directly correlate variations in atmospheric trace element input to fluctuations in the EAM. For example we are able to link Se input into the CLP to EAM derived precipitation. In interglacial climatic periods from 2.3-1.56Ma and 1.50-1.29Ma, we find very strong positive correlations between Se concentration and the summer monsoon index, a proxy for effective precipitation. In later interglacial periods from 1.26-0.83Ma and 0.78-0.16Ma, we find dust input plays a greater role. Our findings demonstrate that the CLP is a valuable environmental archive of atmospheric trace element deposition and suggest that other loess deposits worldwide may serve as useful records for investigating long term natural variations in atmospheric trace element cycling.

Serum Concentrations of Trace Elements in Patients with Tuberculosis and Its Association with Treatment Outcome

PubMed Central

Choi, Rihwa; Kim, Hyoung-Tae; Lim, Yaeji; Kim, Min-Ji; Kwon, O Jung; Jeon, Kyeongman; Park, Hye Yun; Jeong, Byeong-Ho; Koh, Won-Jung; Lee, Soo-Youn

2015-01-01

Deficiencies in essential trace elements are associated with impaired immunity in tuberculosis infection. However, the trace element concentrations in the serum of Korean patients with tuberculosis have not yet been investigated. This study aimed to compare the serum trace element concentrations of Korean adult patients with tuberculosis with noninfected controls and to assess the impact of serum trace element concentration on clinical outcome after antituberculosis treatment. The serum concentrations of four trace elements in 141 consecutively recruited patients with tuberculosis and 79 controls were analyzed by inductively coupled plasma-mass spectrometry. Demographic characteristics were also analyzed. Serum cobalt and copper concentrations were significantly higher in patients with tuberculosis compared with controls, while zinc and selenium concentrations were significantly lower (p < 0.01). Moreover, serum selenium and zinc concentrations were positively correlated (ρ = 0.41, p < 0.05). A high serum copper concentration was associated with a worse clinical outcome, as assessed after one month of antituberculosis therapy. Specifically, culture-positive patients had higher serum copper concentrations than culture-negative patients (p < 0.05). Patients with tuberculosis had altered serum trace element concentrations. Further research is needed to elucidate the roles of individual trace elements and to determine their clinical impact on patients with tuberculosis. PMID:26197334

Titanium and Zirconium Levels Are Associated with Changes in MicroRNAs Expression: Results from a Human Cross-Sectional Study on Obese Population

PubMed Central

Dioni, Laura; Angelici, Laura; Vigna, Luisella; Farronato, Giampietro; Pesatori, Angela Cecilia; Bollati, Valentina

2016-01-01

Objectives In this study on 90 individuals we aimed at evaluating the microRNAs (miRNAs) expression profile associated with personal levels of Titanium (Ti) and Zirconium (Zr) traced in hair samples. Ti and Zr materials are broadly used for dental implants but the biological reactions triggered by a long term presence of these materials in the oral cavity still need to be assessed. MiRNAs are mechanisms that need to be investigated as they play a fundamental role in the control of gene expression following external stimuli and contribute to a wide range of pathophysiological processes. Methods Using the TaqMan® Low-Density Array, we assessed the expression levels of 377 human miRNAs in peripheral blood of 90 subjects. Hair samples were analyzed for Ti and Zr content using Inductively Coupled Plasma-Mass Spectrometry. We performed multivariable regression analysis to investigate the effects of Ti and Zr exposure on miRNA expression levels. We used the Ingenuity Pathway Analysis (IPA) software to explore the functional role of the investigated miRNAs and the related target genes. Results Seven miRNAs (miR-99b, miR-142-5p, miR-152, miR-193a-5p, miR-323-3p, miR-335, miR-494) resulted specifically associated with Zr levels. The functional target analysis showed that miRNAs are involved in mechanisms such as inflammation, skeletal and connective tissue disorders. Conclusions Our data suggest that Zr is more bioactive than Ti and show that miRNAs are relevant molecular mechanisms sensitive to Zr exposure. PMID:27611787

AN EVALUATION OF POTENTIAL LINER MATERIALS FOR ELIMINATING FCCI IN IRRADIATED METALLIC NUCLEAR FUEL ELEMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

D. D. Keiser; J. I. Cole

2007-09-01

Metallic nuclear fuels are being looked at as part of the Global Nuclear Energy Program for transmuting longlive transuranic actinide isotopes contained in spent nuclear fuel into shorter-lived fission products. In order to optimize the performance of these fuels, the concept of using liners to eliminate the fuel/cladding chemical interactions that can occur during irradiation of a fuel element has been investigated. The potential liner materials Zr and V have been tested using solid-solid diffusion couples, consisting of liner materials butted against fuel alloys and against cladding materials. The couples were annealed at the relatively high temperature of 700°C. Thismore » temperature would be the absolute maximum temperature present at the fuel/cladding interface for a fuel element in-reactor. Analysis was performed using a scanning electron microscope equipped with energy-dispersive and wavelengthdispersive spectrometers (SEM/EDS/WDS) to evaluate any developed diffusion structures. At 700°C, minimal interaction was observed between the metallic fuels and either Zr or V. Similarly, limited interaction was observed between the Zr and V and the cladding materials. The best performing liner material appeared to be the V, based on amounts of interaction.« less

[Contents of ten trace elements in Epimedium acuminatum Franch. and its different processed products].

PubMed

Chen, H L; Wang, J K; Ren, Y Q; Wu, Z Y

2001-03-01

Determine and compare the contents of ten trace elements in crude E. acuminatum and its three different processed products. Using flame atomic absorption spectrometry. The ten trace elements were found in both the crude drug and its three processed products, and in terms of contents some of the trace elements in all the three processed products are higher than those in the crude drug. According to the trace element contents, the three processed products of E. acuminatum have their own advantages. It is thus suggested that thoroughgoing clinical and experimental researches be performed anew for the long-shelved processing methods.

Role of ZrO 2 in Promoting the Activity and Selectivity of Co-Based Fischer–Tropsch Synthesis Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Gregory R.; Bell, Alexis T.

2015-11-17

The effects of Zr promotion on the structure and performance of Co-based Fischer-Tropsch synthesis (FTS) catalysts were investigated. Inclusion of Zr in the catalysts was found to increase the FTS turnover frequency and the selectivity to C 5+ hydrocarbons and to decrease the selectivity to methane under most operating conditions. These improvements to the catalytic performance are a function of Zr loading up to an atomic ratio of Zr/Co = 1.0, above which the product selectivity is insensitive to higher concentrations of the promoter. Characterization of the Co nanoparticles by different methods demonstrated that the optimal Zr loading corresponds tomore » half monolayer coverage of the Co surface by the promoter. Measurements of the rate of FTS at different pressures and temperatures established that the kinetics data for both the Zr-promoted and unpromoted catalysts are described by a two-parameter Langmuir-Hinshelwood expression. The parameters used to fit this rate law to the experimental data indicate that the apparent rate coefficient and the CO adsorption constant for the Zr-promoted catalysts are higher than those for the unpromoted catalyst. Elemental mapping by means of STEM-EDS provided evidence that Zr is highly dispersed over the catalyst surface and has limited preference for association with the Co nanoparticles. In situ X-ray absorption spectroscopy confirmed the absence of mixing between the Zr and Co in the nanoparticles. Here, these results suggest that Zr exists as a partial layer of ZrO 2 on the surface of the Co metal nanoparticles. Accordingly, it is proposed that Zr promotion effects originate from sites of enhanced activity at the interface between Co and ZrO 2. The possibility that ZrO 2 acts as a Lewis acid to assist in CO dissociation as well as to increase the ratio of CO to H adsorbed on the catalyst surface is discussed.« less

Petrogenesis of Western Cascades Silicic Volcanics Near Sweet Home, Oregon

NASA Astrophysics Data System (ADS)

Cook, G. W.; White, C. M.

2002-12-01

Silicic lavas in the Menagerie Wilderness east of Sweet Home, Oregon are Oligocene to Miocene in age and range in composition from dacite (low K) to trachydacite (high K) and rhyolite (medium K). Three distinct silicic centers have been distinguished through a combination of field observation, chemistry and petrography. Phenocryst assemblages in rocks of the centers are plagioclase-hornblende-magnetite (Rooster Rock rhyolite), plagioclase-quartz-magnetite (Soda Fork rhyolite) and quartz-plagioclase-biotite-hornblende-magnetite (Moose Mt. rhyolite). The silicic volcanics in the study area are similar in terms of mineral content and overall chemical composition. Despite this, chemical evidence suggests that the three centers are petrologically unrelated. REE variations and least squares modeling of major element compositions are consistent with fractionation of plagioclase and hornblende. The rhyolites have moderate Eu anomalies and have flat MREE and HREE signatures. Least squares models and bivariate plots of major and trace elements also suggest fractionation of the aforementioned phases for both the andesite to dacite, and dacite to rhyolite steps. Comparisons with similar silicic centers show the Menagerie rocks share affinities with High Cascades rocks thought to have been derived through fractional crystallization (Crater Lake and South Sister). Plots of ratios of incompatible trace elements were utilized to determine if assimilation played some role alongside fractional crystallization in differentiation. Plots of Ba/La vs. Ba, Rb/Zr vs. Rb and Rb/Th vs. Rb show systematic positive increases in the ratios between a plausible parent magma (icelandite) and the rhyolites. These increases are not easily explained by fractional crystallization but can be modeled by assimilation of silicic crust. Overall, it seems likely that the three centers evolved independently through similar petrogenetic processes from an andesitic parent. The most plausible petrogenetic scenario involves some combination of fractional crystallization and assimilation of partial melts of silicic crust.

Trace-element geochemistry of metabasaltic rocks from the Yukon-Tanana Upland and implications for the origin of tectonic assemblages in east-central Alaska

USGS Publications Warehouse

Dusel-Bacon, C.; Cooper, K.M.

1999-01-01

We present major- and trace- element geochemical data for 27 amphibolites and six greenstones from three structural packages in the Yukon-Tanana Upland of east-central Alaska: the Lake George assemblage (LG) of Devono-Mississippian augen gneiss, quartz-mica schist, quartzite, and amphibolite; the Taylor Mountain assemblage (TM) of mafic schist and gneiss, marble, quartzite, and metachert; and the Seventymile terrane of greenstone, serpentinized peridotite, and Mississippian to Late Triassic metasedimentary rocks. Most LG amphibolites have relatively high Nb, TiO2, Zr, and light rare earth element contents, indicative of an alkalic to tholeiitic, within-plate basalt origin. The within-plate affinities of the LG amphibolites suggest that their basaltic parent magmas developed in an extensional setting and support a correlation of these metamorphosed continental-margin rocks with less metamorphosed counterparts across the Tintina fault in the Selwyn Basin of the Canadian Cordillera. TM amphibolites have a tholeiitic or calc-alkalic composition, low normalized abundances of Nb and Ta relative to Th and La, and Ti/V values of <20, all indicative of a volcanic-arc origin. Limited results from Seventymile greenstones indicate a tholeiitic or calc-alkalic composition and intermediate to high Ti/V values (27-48), consistent with either a within-plate or an ocean-floor basalt origin. Y-La-Nb proportions in both TM and Seventymile metabasalts indicate the proximity of the arc and marginal basin to continental crust. The arc geochemistry of TM amphibolites is consistent with a model in which the TM assemblage includes arc rocks generated above a west-dipping subduction zone outboard of the North American continental margin in mid-Paleozoic through Triassic time. The ocean-floor or within-plate basalt geochemistry of the Seventymile greenstones supports the correlation of the Seventymile terrane with the Slide Mountain terrane in Canada and the hypothesis that these oceanic rocks originated in a basin between the continental margin and an arc to the west.

Spectral, electron microscopic and chemical investigations of gamma-induced purple color zonings in amethyst crystals from the Dursunbey-Balıkesir region of Turkey

NASA Astrophysics Data System (ADS)

Hatipoğlu, Murat; Kibar, Rana; Çetin, Ahmet; Can, Nurdoğan; Helvacı, Cahit; Derin, H.

2011-07-01

Amethyst crystals on matrix specimens from the Dursunbey-Balıkesir region in Turkey have five representative purple color zonings: dark purple, light purple, lilac, orchid, and violet. The purple color zonings have been analyzed with optical absorption spectra in the visible wavelength region, chemical full trace element analyses (inductively coupled plasma-atomic emission spectroscopy and inductively coupled plasma-mass spectroscopy), and scanning electron microscopic images with high magnification. It can be proposed that the production of the purple color in amethyst crystals is due to three dominant absorption bands centered at 375, 530, and 675 nm, respectively. In addition, the purple color zonings are also due to four minor absorption bands centered at 435, 480, 620, and 760 nm. X-ray diffraction graphics of the investigated amethyst crystals indicate that these crystals are composed of a nearly pure alpha-quartz phase and do not include any moganite silica phase and/or other mineral implications. Trace element analyses of the amethyst crystals show five representative purple color zonings, suggesting that the absorption bands can be mainly attributed to extrinsic defects (chemical impurities). However, another important factor that influences all structural defects in amethyst is likely to be the gamma irradiation that exists during amethyst crystallization and its inclusion in host materials. This gamma irradiation originates from the large underlying intrusive granitoid body in the region of amethyst formation. Irradiation modifies the valence values of the impurity elements in the amethyst crystals. It is observed that the violet-colored amethyst crystals have the most stable and the least reversible coloration when exposed to strong light sources. This situation can be related to the higher impurity content of Fe (2.50 ppm), Co (3.1 ppm), Ni (38 ppm), Cu (17.9 ppm), Zn (10 ppm), Zr (3.9 ppm), and Mo (21.8 ppm).

The Effects of Various Amendments on Trace Element Stabilization in Acidic, Neutral, and Alkali Soil with Similar Pollution Index

PubMed Central

Kim, Min-Suk; Min, Hyun-Gi; Lee, Sang-Hwan; Kim, Jeong-Gyu

2016-01-01

Many studies have examined the application of soil amendments, including pH change-induced immobilizers, adsorbents, and organic materials, for soil remediation. This study evaluated the effects of various amendments on trace element stabilization and phytotoxicity, depending on the initial soil pH in acid, neutral, and alkali conditions. As in all types of soils, Fe and Ca were well stabilized on adsorption sites. There was an effect from pH control or adsorption mechanisms on the stabilization of cationic trace elements from inorganic amendments in acidic and neutral soil. Furthermore, acid mine drainage sludge has shown great potential for stabilizing most trace elements. In a phytotoxicity test, the ratio of the bioavailable fraction to the pseudo-total fraction significantly affected the uptake of trace elements by bok choy. While inorganic amendments efficiently decreased the bioavailability of trace elements, significant effects from organic amendments were not noticeable due to the short-term cultivation period. Therefore, the application of organic amendments for stabilizing trace elements in agricultural soil requires further study. PMID:27835687

Assessment of trace element contamination of urban surface soil at informal industrial sites in a low-income country.

PubMed

Kanda, Artwell; Ncube, France; Hwende, Tamuka; Makumbe, Peter

2018-05-29

Trace elements released by human activity are ubiquitously detected in surface soil. The trace element contamination statuses of 20 sampling stations at two busy informal industrial sites of Harare city, Zimbabwe, were evaluated using geochemical indices. Spectrophotometric determinations of concentrations of trace elements in surface soil indicated generally higher values than the reference site and the average upper earth's crust. High contamination factors were observed for trace elements across sampling stations at Gazaland and Siyaso informal industrial sites. Concentrations exhibited heterogeneous distribution of trace elements in surface soil varying with the nature of activity at a sampling station. The pollution load index and degree of contamination suggested highly contaminated surface soil with Cd, Cu and Pb particularly where the following activities were done: (1) welding, (2) automobile maintenance and (3) waste dumping. These results may be very important to reduce soil contamination. Paving surfaces may help to reduce dispersal of trace elements deposited on surface soil to other stations and minimise human exposure via inhalation and contact.

Risk assessment of trace elements in cultured freshwater fishes from Jiangxi province, China.

PubMed

Zhang, Li; Zhang, Dawen; Wei, Yihua; Luo, Linguan; Dai, Tingcan

2014-04-01

The levels of trace elements (As, Cd, Cr, Cu, Fe, Ni, Pb, Se, and Zn) in eight species of cultured freshwater fishes from Jiangxi province were determined by inductively coupled plasma-mass spectroscopy. All the studied trace element levels in fish muscles from Jiangxi province did not exceed Chinese national standard and European Union standard, and they were often lower than previous studies. The calculated target hazard quotient values for all the studied trace elements in fish samples were much less than 1, suggesting that the studied trace elements in fish muscles from Jiangxi province had not pose obvious health hazards to consumers. As and Cd concentrations in northern snakehead were much higher than that in other fishes, demonstrating that this fish species could be valuable as a bioindicator of As and Cd in environmental surveys. In addition, the highest concentrations of Fe, Zn, and moderate contents of other essential trace elements in crucian carp indicated that crucian carp could be a good nutrient source of essential trace elements for human health.

The Effects of Various Amendments on Trace Element Stabilization in Acidic, Neutral, and Alkali Soil with Similar Pollution Index.

PubMed

Kim, Min-Suk; Min, Hyun-Gi; Lee, Sang-Hwan; Kim, Jeong-Gyu

2016-01-01

Many studies have examined the application of soil amendments, including pH change-induced immobilizers, adsorbents, and organic materials, for soil remediation. This study evaluated the effects of various amendments on trace element stabilization and phytotoxicity, depending on the initial soil pH in acid, neutral, and alkali conditions. As in all types of soils, Fe and Ca were well stabilized on adsorption sites. There was an effect from pH control or adsorption mechanisms on the stabilization of cationic trace elements from inorganic amendments in acidic and neutral soil. Furthermore, acid mine drainage sludge has shown great potential for stabilizing most trace elements. In a phytotoxicity test, the ratio of the bioavailable fraction to the pseudo-total fraction significantly affected the uptake of trace elements by bok choy. While inorganic amendments efficiently decreased the bioavailability of trace elements, significant effects from organic amendments were not noticeable due to the short-term cultivation period. Therefore, the application of organic amendments for stabilizing trace elements in agricultural soil requires further study.

Effects of alloying elements on the formation of < c >-component loops in Zr alloy Excel under heavy ion irradiation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Idrees, Yasir; Francis, Elisabeth M.; Yao, Zhongwen

2015-05-14

We report here the microstructural changes occurring in the zirconium alloy Excel (Zr-3.5 wt% Sn-0.8Nb-0.8Mo-0.2Fe) during heavy ion irradiation. In situ irradiation experiments were conducted at reactor operating temperatures on two Zr Excel alloy microstructures with different states of alloying elements, with the states achieved by different solution heat treatments. In the first case, the alloying elements were mostly concentrated in the beta (beta) phase, whereas, in the second case, large Zr-3(Mo,Nb,Fe)(4) secondary phase precipitates (SPPs) were grown in the alpha (alpha) phase by long term aging. The heavy ion induced damage and resultant compositional changes were examined using transmissionmore » electron microscopy (TEM) in combination with scanning transmission electron microscope (STEM)-energy dispersive x-ray spectroscopy (EDS) mapping. Significant differences were seen in microstructural evolution between the two different microstructures that were irradiated under similar conditions. Nucleation and growth of < c >-component loops and their dependence on the alloying elements are a major focus of the current investigation. It was observed that the < c >-component loops nucleate readily at 100, 300, and 400 degrees C after a threshold incubation dose (TID), which varies with irradiation temperature and the state of alloying elements. It was found that the TID for the formation of < c >-component loops increases with decrease in irradiation temperature. Alloying elements that are present in the form of SPPs increase the TID compared to when they are in the beta phase solid solution. Dose and temperature dependence of loop size and density are presented. Radiation induced redistribution and clustering of alloying elements (Sn, Mo, and Fe) have been observed and related to the formation of < c >-component loops. It has been shown that at the higher temperature tests, irradiation induced dissolution of precipitates occurs whereas irradiation induced amorphization occurs at 100 degrees C. Furthermore, dose and temperature seem to be the main factors governing the dissolution of SPPs and redistribution of alloying elements, which in turn controls the nucleation and growth of < c >-component loops. The correlation between the microstructural evolution and microchemistry has been found by EDS and is discussed in detail.« less

Zircon solubility and of Zr species in subduction zone fluids

NASA Astrophysics Data System (ADS)

Wilke, M.; Schmidt, C.; Rickers, K.; Pascarelli, S.; Manning, C. E.; Stechern, A.

2009-12-01

The geochemical signature of igneous rocks at convergent plate margins is thought to result from complex melt formation processes involving aqueous solutions derived from dehydration of the subducted slab. In these processes, the depletion of high-field-strength elements (HFSE) may be controlled by the presence of accessory phases such as zircon and rutile, which can strongly fractionate these elements; however, the stability and solubility of these phases depends strongly on the fluid composition, including concentration and stoichiometry of Na-Al silicate components. Here we present new data on the influence of the fluid composition on zircon solubility as well as data on the Zr complexation in these fluids at P&T. Experiments were conducted using a modified hydrothermal diamond-anvil cell (HDAC). Zr contents at P&T were determined using SR-µXRF spectra. Zr K-edge X-ray Absorption Fine Structure (XAFS) spectra were acquired to investigate the Zr complexation in-situ at P&T. A grain of synthetic crystalline zircon was equilibrated with an aqueous fluid containing Na2Si2O5 or Na2Si2O5 + Al2O3 components. XAFS and SR-µXRF spectra were taken at the dispersive beamline ID24 of the ESRF, Grenoble, France. Some additional SR-µXRF spectra were taken at HASYLAB, Hamburg, beamline L. The observed Zr concentrations in fluids containing 7-33 wt% Na2Si2O5 and variable Al contents were between 75 and 720 ppm at 500 to 750°C and ~300 MPa to ~700 MPa. These values match expected solubilities calculated from linear interpolation of the maximum solubility in pure H2O (from the detection limit) and the solubility in the most alkaline high-silica melts reported by Ellison and Hess (1986, CMP, 94, 343). The high Zr solubility in sodium silicate-bearing solutions signifies that aqueous fluids with alkali silicates offer an efficient mechanism for HFSE transport. This can be explained by complexation of HFSE with Si, Na, and perhaps also Al, via formation of polymerized solutes. The XAFS results show clear differences between spectra of Zr in an HCl solution and in H2O-Na2Si2O5 (±Al2O3) aqueous fluid, implying considerable differences in Zr complexation. The latter spectra display similarities to spectra of Zr in Na2Si2O5 glass. This may indicate a similar structural environment for the two examined states, and thus point to Zr in (alumino)-silicate-based polymeric units in the aqueous solutions.

Methods for detecting the mobility of trace elements during medium-temperature pyrolysis

USGS Publications Warehouse

Shiley, R.H.; Konopka, K.L.; Cahill, R.A.; Hinckley, C.C.; Smith, Gerard V.; Twardowska, H.; Saporoschenko, Mykola

1983-01-01

The mobility (volatility) of trace elements in coal during pyrolysis has been studied for distances of up to 40 cm between the coal and the trace element collector, which was graphite or a baffled solvent trap. Nineteen elements not previously recorded as mobile were detected. ?? 1983.

The role of high-energy synchrotron radiation in biomedical trace element research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pounds, J.G.; Long, G.J.; Kwiatek, W.M.

1987-01-01

This paper will present the results of an investigation of the distribution of essential elements in the normal hepatic lobule. the liver is the organ responsible for metabolism and storage of most trace elements. Although parenchymal hepatocytes are rather uniform histologically, morphometry, histochemistry, immunohistochemistry, and microdissection with microchemical investigations have revealed marked heterogeneity on a functional and biochemical level. Hepatocytes from the periportal and perivenous zones of the liver parrenchyma differ in oxidative energy metabolism, glucose uptake and output, unreagenesis, biotransformation, bile acid secretion, and palsma protein synthesis and secretion. Although trace elements are intimately involved in the regulation andmore » maintenance of these functions, little is known regarding the heterogeneity of trace element localization of the liver parenchyma. Histochemical techniques for trace elements generally give high spatial resolution, but lack specificity and stoichiometry. Microdissection has been of marginal usefulness for trace element analyses due to the very small size of the dissected parenchyma. The characteristics of the high-energy x-ray microscope provide an effective approach for elucidating the trace element content of these small biological structures or regions. 5 refs., 1 fig., 1 tab.« less

The influence of carbon, sulfur, and silicon on trace element partitioning in iron alloys

NASA Astrophysics Data System (ADS)

Han, J.; Van Orman, J. A.; Crispin, K. L.; Ash, R. D.

2014-12-01

Non-metallic light elements are important constituents of planetary cores and have a strong influence on the partitioning behavior of trace elements. Planetary cores may contain a wide range of non-metallic light elements, including H, N, S, P, Si, and C. Under highly reducing conditions, such as those that are thought to have pertained during the formation of Mercury's core, Si and C, in addition to sulfur, may be particularly important constituents. Each of these elements may strongly effect and have a different impact on the partitioning behavior of trace elements but their combined effects on trace element partitioning have not been quantified. We investigated the partitioning behavior of more than 25 siderophile trace elements within the Fe-S-C-Si system with varying concentrations of C, S, and Si. The experiments were performed under pressures varying from 1 atm to 2 GPa and temperatures ranging from 1200˚C to 1450˚C. All experiments produced immiscible liquids, one enriched in Si and C, and the other predominantly FeS. We found some highly siderophile elements including Os, Ru, Ir, and Re are much more enriched in Fe-Si-C phase than in Fe-S phase, whereas other trace elements like V, Co, Ag, Hf, and Pb are enriched in S-rich phase. However, not all the trace elements enriched in Fe-Si-C phase are repelled by sulfur. Elements like Re and Ru could have different partitioning trends if sulfur concentration in S-rich phase rises. The partitioning behavior of these trace elements could enhance our understanding of the differentiation of Mercury's core under oxygen-poor conditions.

Maternal transfer of trace elements in the Atlantic horseshoe crab (Limulus polyphemus).

PubMed

Bakker, Aaron K; Dutton, Jessica; Sclafani, Matthew; Santangelo, Nicholas

2017-01-01

The maternal transfer of trace elements is a process by which offspring may accumulate trace elements from their maternal parent. Although maternal transfer has been assessed in many vertebrates, there is little understanding of this process in invertebrate species. This study investigated the maternal transfer of 13 trace elements (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) in Atlantic horseshoe crab (Limulus polyphemus) eggs and compared concentrations to those in adult leg and gill tissue. For the majority of individuals, all trace elements were transferred, with the exception of Cr, from the female to the eggs. The greatest concentrations on average transferred to egg tissue were Zn (140 µg/g), Cu (47.8 µg/g), and Fe (38.6 µg/g) for essential elements and As (10.9 µg/g) and Ag (1.23 µg/g) for nonessential elements. For elements that were maternally transferred, correlation analyses were run to assess if the concentration in the eggs were similar to that of adult tissue that is completely internalized (leg) or a boundary to the external environment (gill). Positive correlations between egg and leg tissue were found for As, Hg, Se, Mn, Pb, and Ni. Mercury, Mn, Ni, and Se were the only elements correlated between egg and gill tissue. Although, many trace elements were in low concentration in the eggs, we speculate that the higher transfer of essential elements is related to their potential benefit during early development versus nonessential trace elements, which are known to be toxic. We conclude that maternal transfer as a source of trace elements to horseshoe crabs should not be overlooked and warrants further investigation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karayigit, A.I.; Bulut, Y.; Karayigit, G.

A total of 48 samples, feed coals (FCs), fly ashes (FAs) and bottom ashes (BAs), which were systematically collected once a week over an eight-week period from boiler units, B1-4 with 660 MW and B5-6 with 330 MW capacity from Soma power plant, have been evaluated for major and trace elements (Al, Ca, Fe, K, Mg, Mn, Na, Ti, S, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Cs, Ga, Ge, Hf, Hg, Li, Mo, Nb, Ni, P, Pb, Rb, Sb, Sc, Se, Sn, Sr, Ta, Th, Tl, U, V, Y, Zn, Zr, and REEs) to get information onmore » behavior during coal combustion. This study indicates that some elements such as Hg, Bi, Cd, As, Pb, Ge, Tl, Sn, Zn, Sb, B show enrichments in FAs relative to the BAs in both group boiler units. In addition to these, Cs, Lu, Tm, and Ga in Units B1-4 and S in Units B5-6 also have enrichments in FAs. Elements showing enrichments in BAs in both group boiler units are Ta, Mn, Nb. In addition to these, Se, Ca, Mg, Na, Fe in Units B1-4 and Cu in Units B5-6 also have enrichments in BAs. The remaining elements investigated in this study have no clear segregation between FAs and BAs. Mass balance calculations with the two methods show that some elements, S, Ta, Hg, Se, Zn, Na, Ca in Units B1-4, and Hg, S, Ta, Se, P in Units B5-6, have volatile behavior during coal combustion in the Soma power plant. This study also implies that some elements, Sb and Tb in Units B1-4 and Sb in Units B5-6, have relatively high retention effects in the combustion residues from the Soma power plant.« less

Detrital and oceanic dysoxia influence on OAE2 sediment geochemistry from Tarfaya, SW Morocco

NASA Astrophysics Data System (ADS)

Turgeon, S. C.; Kolonic, S.; Brumsack, H.-J.; Wagner, T.

2003-04-01

The Cretaceous "greenhouse" world's stratigraphic record is punctuated by several important organic-rich intervals representing quasi-global "Oceanic Anoxic Events" (OAEs). This study focuses on sediments from Tarfaya in SW Morocco deposited during the Cenomanian-Turonian Boundary Event (CTBE or OAE2 at 93.5 Ma). These sediments consist of distinctly laminated, carbonate-rich black shales alternating with lighter coloured structureless intervals and sporadic chert lenses. Sediments from three sites representing proximal to distal settings were studied. Samples were analysed for Ctot, Corg, Stot, as well as several major-, minor- and trace elements using XRF and ICP-MS. These sediments are characterised by high Corg, Stot, and CaCO3 contents and consist of a simple two component mixing system ("average shale"-CaCO3). Major element concentrations are low, except for Ca and P, owing in part to the carbonate dilution effect. Most elements plot along "average shale" lines. Elements such as Si, Ti, Fe, K, Rb, and Zr show positive relationships with Al2O3, pointing to homogeneous source area material. Several Al-normalised elements (As, Ba, Cr, Cu, Ni, Sr, U, V, Y, Zn), many of them redox-sensitive or sulphide-residing, are enriched in the sediments indicating an oxygen-depleted environment and potential availability of hydrogen sulfide in the water column at the time of deposition. High Zn concentrations suggest increased submarine volcanism and/or hydrothermal activity during this time interval. High Ba concentrations are possibly indicative of high regional paleoproductivity, which is further supported by the elevated P concentrations hinting at nutrient availability. Basinward trends in the geochemical distribution of some elements are apparent and probably reflect the decreasing influence of terrestrial sediments away from the shoreline.

Remediation using trace element humate surfactant

DOEpatents

Riddle, Catherine Lynn; Taylor, Steven Cheney; Bruhn, Debra Fox

2016-08-30

A method of remediation at a remediation site having one or more undesirable conditions in which one or more soil characteristics, preferably soil pH and/or elemental concentrations, are measured at a remediation site. A trace element humate surfactant composition is prepared comprising a humate solution, element solution and at least one surfactant. The prepared trace element humate surfactant composition is then dispensed onto the remediation site whereby the trace element humate surfactant composition will reduce the amount of undesirable compounds by promoting growth of native species activity. By promoting native species activity, remediation occurs quickly and environmental impact is minimal.

Zirconium Carbide Produced by Spark Plasma Sintering and Hot Pressing: Densification Kinetics, Grain Growth, and Thermal Properties

PubMed Central

Wei, Xialu; Back, Christina; Izhvanov, Oleg; Haines, Christopher D.; Olevsky, Eugene A.

2016-01-01

Spark plasma sintering (SPS) has been employed to consolidate a micron-sized zirconium carbide (ZrC) powder. ZrC pellets with a variety of relative densities are obtained under different processing parameters. The densification kinetics of ZrC powders subjected to conventional hot pressing and SPS are comparatively studied by applying similar heating and loading profiles. Due to the lack of electric current assistance, the conventional hot pressing appears to impose lower strain rate sensitivity and higher activation energy values than those which correspond to the SPS processing. A finite element simulation is used to analyze the temperature evolution within the volume of ZrC specimens subjected to SPS. The control mechanism for grain growth during the final SPS stage is studied via a recently modified model, in which the grain growth rate dependence on porosity is incorporated. The constant pressure specific heat and thermal conductivity of the SPS-processed ZrC are determined to be higher than those reported for the hot-pressed ZrC and the benefits of applying SPS are indicated accordingly. PMID:28773697

Zirconium Carbide Produced by Spark Plasma Sintering and Hot Pressing: Densification Kinetics, Grain Growth, and Thermal Properties

DOE PAGES

Wei, Xialu; Back, Christina; Izhvanov, Oleg; ...

2016-07-14

Spark plasma sintering (SPS) has been employed to consolidate a micron-sized zirconium carbide (ZrC) powder. ZrC pellets with a variety of relative densities are obtained under different processing parameters. The densification kinetics of ZrC powders subjected to conventional hot pressing and SPS are comparatively studied by applying similar heating and loading profiles. Due to the lack of electric current assistance, the conventional hot pressing appears to impose lower strain rate sensitivity and higher activation energy values than those which correspond to the SPS processing. A finite element simulation is used to analyze the temperature evolution within the volume of ZrCmore » specimens subjected to SPS. The control mechanism for grain growth during the final SPS stage is studied via a recently modified model, in which the grain growth rate dependence on porosity is incorporated. Finally, the constant pressure specific heat and thermal conductivity of the SPS-processed ZrC are determined to be higher than those reported for the hot-pressed ZrC and the benefits of applying SPS are indicated accordingly.« less

Bio-corrosion and cytotoxicity studies on novel Zr 55Co 30Ti 15 and Cu 60Zr 20Ti 20 metallic glasses

DOE PAGES

Vincent, S.; Daiwile, A.; Devi, S. S.; ...

2014-09-26

Metallic glasses are a potential and compatible implant candidate for biomedical applications. In the present investigation, a comparative study between novel Zr 55Co 30Ti 15 and Cu 60Zr 20Ti 20 metallic glasses is carried out to evaluate in vitro biocompatibility using simulated body fluids. The bio-corrosion behavior of Zr- and Cu-based metallic glasses in different types of artificial body fluids such as artificial saliva solution, phosphate-buffered saline solution, artificial blood plasma solution, and Hank’s balanced saline solution is evaluated using potentiodynamic polarization studies at a constant body temperature of 310.15 K (37 °C). Surface morphology of samples after bio-corrosion experimentsmore » was observed by scanning electron microscopy. In vitro cytotoxicity test on glassy alloys were performed using human osteosarcoma cell line as per 10993-5 guidelines from International Organization for Standardization. As a result, the comparative study between Zr- and Cu-based glassy alloys provides vital information about the effect of elemental composition on biocompatibility of metallic glasses.« less

FTIR, magnetic, 1H NMR spectral and thermal studies of some chelates of caproic acid: inhibitory effect on different kinds of bacteria.

PubMed

Refat, Moamen S; El-Korashy, Sabry A; Kumar, Deo Nandan; Ahmed, Ahmed S

2008-06-01

A convenient method for the preparation of complexes of the Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, ZrO2+, UO2(2+), Zr4+ and Th4+ ions with caproic acid (Hcap) is reported and this has enabled 10 complexes of caproate anion to be formulated: [Cr(cap)3].5H2O, [Mn(cap)2(H2O)2], [Fe(cap)3].12H2O, [Co(cap)2(H2O)2].4H2O, [Ni(cap)2(H2O)2].3H2O, [Zn(cap)2], [ZrO(cap)2].3H2O, [UO2(cap)(NO3)], [Zr(cap)2(Cl)2] and [Th(cap)4]. These new complexes were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid infrared, 1H NMR and UV-vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. It has been found from the elemental analysis as well as thermal studies that the caproate ligand behaves as bidentate ligand and forming chelates with 1:1 (metal:ligand) stoichiometry for UO2(2+), 1:2 for (Mn2+, Co2+, Ni2+, Zn2+, ZrO2+ and Zr4+), 1:3 stoichiometry for (Cr3+ and Fe3+) and 1:4 for Th4+ caproate complexes, respectively, as bidentate chelating. The molar conductance measurements proved that the caproate complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* are estimated from the DTG curves. The antibacterial activity of the caproic acid and their complexes was evaluated against some gram positive/negative bacteria.

Trace element and stable isotope analysis of fourteen species of marine invertebrates from the Bay of Fundy, Canada.

PubMed

English, Matthew D; Robertson, Gregory J; Mallory, Mark L

2015-12-15

The Bay of Fundy, Canada, is a macrotidal bay with a highly productive intertidal zone, hosting a large abundance and diversity of marine invertebrates. We analysed trace element concentrations and stable isotopic values of δ(15)N and δ(13)C in 14 species of benthic marine invertebrates from the Bay of Fundy's intertidal zone to investigate bioaccumulation or biodilution of trace elements in the lower level of this marine food web. Barnacles (Balanus balanus) consistently had significantly greater concentrations of trace elements compared to the other species studied, but otherwise we found low concentrations of non-essential trace elements. In the range of trophic levels that we studied, we found limited evidence of bioaccumulation or biodilution of trace elements across species, likely due to the species examined occupying similar trophic levels in different food chains. Copyright © 2015 Elsevier Ltd. All rights reserved.

Geochemical consequences of flow differentiation in a multiple injection dike (Trinity ophiolite, N. California)

USGS Publications Warehouse

Brouxel, M.

1991-01-01

A clinopyroxene-rich dike of the Trinity ophiolite sheeted-dike complex shows three different magmatic pulses, probably injected in a short period of time (no well developed chilled margin) and important variations of the clinopyroxene and plagioclase percentages between its core (highly porphyritic) and margins (aphyric). This variation, interpreted as related to a flow differentiation phenomenon (mechanical phenocryst redistribution), has important geochemical consequences. It produces increases in the FeO, MgO, CaO, Cr and Ni contents from the margin to the core, together with increases in the clinopyroxene percentage, and decreases in the SiO2, Zr, Y, Nb and REE contents together with a decrease in the percentage of the fine-grained groundmass toward the core of the dike. This mineralogical redistribution, which also affects the incompatible trace element ratios because of the difference in plagioclase and clinopyroxene mineral/liquid partition coefficients, illustrate the importance of fractionation processes outside of a magma chamber. ?? 1991.

Distribution and environmental assessment of trace elements contamination of water, sediments and flora from Douro River estuary, Portugal.

PubMed

Ribeiro, C; Couto, C; Ribeiro, A R; Maia, A S; Santos, M; Tiritan, M E; Pinto, E; Almeida, A A

2018-10-15

The present study evaluated the content and distribution of several trace elements (Li, Be, Al, V, Cr, Co, Ni, Cu, Zn, Se, Mo, Ag, Cd, Sb, Ba, Tl, Pb, and U) in the Douro River estuary. For that, three matrices were collected (water, sediments and native local flora) to assess the extent of contamination by these elements in this estuarine ecosystem. Results showed their occurrence in estuarine water and sediments, but significant differences were recorded on the concentration levels and pattern of distribution among both matrices and sampling points. Generally, the levels of trace elements were higher in the sediments than in the respective estuarine water. Nonetheless, no correlation among trace elements was determined between water and sediments, except for Cd. Al was the trace element found at highest concentration at both sediments and water followed by Zn. Pollution indices such as geo-accumulation (I geo ), enrichment factor (EF) and contamination factor (CF) were determined to understand the levels and sources of trace elements pollution. I geo showed strong contamination by anthropogenic activities for Li, Al, V, Cr, Ni, Cu, Zn, Ba and Pb at all sampling points while EF and CF demonstrated severe enrichment and contamination by Se, Sb and Pb. Levels of trace elements were compared to acceptable values for aquatic organisms and Sediment Quality Guidelines. The concentration of some trace elements, namely Al, Pb and Cu, were higher than those considered acceptable, with potential negative impact on local living organisms. Nevertheless, permissible values for all trace elements are still not available, demonstrating that further studies are needed in order to have a complete assessment of environmental risk. Furthermore, the occurrence and possible accumulation of trace elements by local plant species and macroalgae were investigated as well as their potential use as bioindicators of local pollution and for phytoremediation purposes. Copyright © 2018 Elsevier B.V. All rights reserved.

Multiproxy Study of a Holocene Record From Western Pescadero Basin, Gulf of California, Mexico: Paleoclimatic inferences

NASA Astrophysics Data System (ADS)

Perez-Cruz, L. L.; Valdez, M.; Roy, P. D.

2013-12-01

A sedimentary sequence (gravity core T-56, 256 cm length) from Pescadero Basin on the western side of the Gulf of California is analyzed as part of a multiproxy study. The core was collected within the Oxygen Minimum Zone (OMZ) at 597 m depth, aboard of the R/V "El Puma". Pescadero basin is located at mouth of the gulf; in a location sensitive to record the changes in the gulf and the Eastern Pacific Ocean. The sedimentary sequence is analyzed to contribute to understanding the climatic variability in the southern part of the gulf of California during the Holocene using geochemistry (major and trace elements and Corg), magnetic properties and benthic foraminifera assemblages as proxy of changes in paleoproductivity, paleoprecipitation and bottom water oxygenation. The core is characterized by silty-clay sediments, and exhibits a turbidite between 130 and 235 cm, distinguished by sandy sediments and reworking material. From 130 cm to the top it shows a visible laminated structure. Chronology is based on six AMS radiocarbon dates, and estimated sedimentation rates are 0.22, 0.18, 0.17 and 0.05 mm/yr. The core covers c. last 10,500 years. Variations in major and trace elements (Ti, K, Al, K, Zr) and magnetic susceptibility indicate fluctuations in terrigenous input related to changes in hydrological conditions, Benthic foraminifera assemblages and Corg along the sequence indicate that Pescadero basin is sensitive to paleoceanographic changes. Corg and benthic foraminiferal assemblages show downcore variations related to paleoproductivity changes. For the Early Holocene, low values of Corg and epifaunal benthic foraminifera suggest oxic conditions in bottom waters and strong stratification with low productivity. Organic carbon shows higher values towards the bottom of the core, for the last 1300 years.

Geochemistry of sandstones from the Pliocene Gabir Formation, north Marsa Alam, Red Sea, Egypt: Implication for provenance, weathering and tectonic setting

NASA Astrophysics Data System (ADS)

Zaid, Samir M.

2015-02-01

Petrographic, major and trace element compositions of sandstones from the Pliocene Gabir Formation, Central Eastern Desert, Egypt have been investigated to determine their provenance, intensity of paleo-weathering of the source rocks and their depositional tectonic setting. Gabir Formation is composed mainly of sandstones alternating with limestone and shale beds. The Gabir sandstone is yellowish gray to yellowish brown color, calcareous and fossiliferous. The composition of this formation refers to shallow warm agitated marine conditions. Texturally, Gabir sandstones are immature, poorly sorted and grain supported. Abundance of feldspars indicates rapid deposition of sediments from a nearby source rocks. Their average modal composition (Q71.35F16.6L12.05), classifies them as sublitharenite and arkose with subordinate litharenite and subarkose, which is also supported by geochemical study. Chemical analyses revealed that sandstones have high SiO2, K2O > Na2O, and low Fe2O3 values, which are consistent with the modal data. Also, sandstone samples are enriched in most trace elements such as Ba, Sr, Ni, Cr and Zr and depleted in U and Th. The petrography and geochemistry suggest that Gabir sandstones were deposited in an active continental margin basin. They were mainly derived from granitic and low grade metamorphic sources. The CIA values (41.69-74.84) of the Gabir sandstones indicate low to moderate degree of chemical weathering, which may reflect cold and/or arid climate conditions in the source area. The source rocks are probably identified to be Proterozoic granites, metagabbros and metavolcanics, which must have been exposed during rifting, initiated during Oligocene and continued till post Miocene.

The Early Toarcian oceanic anoxic event: Paleoenvironmental and paleoclimatic change across the Alpine Tethys (Switzerland)

NASA Astrophysics Data System (ADS)

Fantasia, Alicia; Föllmi, Karl B.; Adatte, Thierry; Spangenberg, Jorge E.; Montero-Serrano, Jean-Carlos

2018-03-01

Paleoenvironmental and paleoclimatic change associated with the Toarcian oceanic anoxic event (T-OAE) was evaluated in five successions located in Switzerland. They represent different paleogeographic settings across the Alpine Tethys: the northern shelf (Gipf, Riniken and Rietheim), the Sub-Briançonnais basin (Creux de l'Ours), and the Lombardian basin (Breggia). The multi-proxy approach chosen (whole-rock and clay mineralogy, phosphorus, major and trace elements) shows that local environmental conditions modulated the response to the T-OAE across the Alpine Tethys. On the northern shelf and in the Sub-Briançonnais basin, high kaolinite contents and detrital proxies (detrital index, Ti, Zr, Si) in the T-OAE interval suggest a change towards a warmer and more humid climate coupled with an increase in the chemical weathering rates. In contrast, low kaolinite content in the Lombardian basin is likely related to a more arid climate along the southern Tethys margin and/or to a deeper and more distal setting. Redox-sensitive trace-element (V, Mo, Cu, Ni) enrichments in the T-OAE intervals reveal that dysoxic to anoxic conditions developed on the northern shelf, whereas reducing conditions were less severe in the Sub-Briançonnais basin. In the Lombardian basin well-oxygenated bottom water conditions prevailed. Phosphorus (P) speciation analysis was performed at Riniken and Creux de l'Ours. This is the first report of P speciation data for T-OAE sections, clearly suggesting that high P contents during this time interval are mainly linked to the presence of an authigenic phases and fish remains. The development of oxygen-depleted conditions during the T-OAE seems to have promoted the release of the organic-bound P back into the water column, thereby further sustaining primary productivity in a positive feedback loop.

Plume dynamics beneath the African plate inferred from the geochemistry of the Tertiary basalts of southern Ethiopia

NASA Astrophysics Data System (ADS)

George, R. M.; Rogers, N. W.

2002-09-01

Southern Ethiopian flood basalts erupted in two episodes: the pre-rift Amaro and Gamo transitional tholeiites (45-35 million years) followed by the syn-extensional Getra-Kele alkali basalts (19-11 million years). These two volcanic episodes are distinct in both trace element and isotope ratios (Zr/Nb ratios in Amaro/Gamo lavas fall between 7 and 14, and 3-4.7 in the Getra-Kele lavas whereas 206Pb/204Pb ratios fall between 18-19 and 18.9-20, respectively). The distinctive chemistries of the two eruptive phases record the tapping of two distinct source regions: a mantle plume source for the Amaro/Gamo phase and an enriched continental mantle lithosphere source for the Getra-Kele phase. Isotope and trace element variations within the Amaro/Gamo lavas reflect polybaric fractional crystallisation initiated at high pressures accompanied by limited crustal contamination. We show that clinopyroxene removal at high (0.5 GPa) crustal pressures provides an explanation for the common occurrence of transitional tholeiites in Ethiopia relative to other, typically tholeiitic flood basalt provinces. The mantle plume signature inferred from the most primitive Amaro basalts is isotopically distinct from that contributing to melt generation in central Ethiopian and Afar. This, combined with Early Tertiary plate reconstructions and similarities with Kenyan basalts farther south, lends credence to derivation of these melts from the Kenyan plume rather than the Afar mantle plume. The break in magmatism between 35 and 19 Ma is consistent with the northward movement away from the Kenya plume predicted from plate tectonic reconstructions. In this model the Getra-Kele magmatism is a response to heating of carbonatitically metasomatised lithosphere by the Afar mantle plume beneath southern Ethiopia at this time.

Geochemical constraints on the provenance and depositional environment of the Messinian sediments, onshore Nile Delta, Egypt: Implications for the late Miocene paleogeography of the Mediterranean

NASA Astrophysics Data System (ADS)

Leila, Mahmoud; Moscariello, Andrea; Šegvić, Branimir

2018-07-01

The Messinian sequence rocks in the Nile Delta present prolific hydrocarbon reservoirs and are, therefore, of great importance from the aspect of petroleum exploration and development strategies. Yet, little is known about their tectonic provenance and depositional setting. This study focuses on the geochemical signatures archived in the Messinian siliciclastic sediments to employ them as a powerful tool to elucidate the basin evolution during the Messinian salinity crisis (MSC). The pre-MSC Qawasim sediments are texturally and compositionally immature. They are enriched in lithic fragments, foraminiferal bioclasts, and rounded heavy minerals suggesting a significant contribution from the pre-existing Cretaceous-Eocene mixed carbonate-siliciclastic rocks bordering the Nile Delta. In contrast, the textural and mineralogical compositions as well as a range of geochemical proxies (e.g., chemical index of alteration and weathering CIA, CIW as well as index of chemical variability ICV and Zr/Sc ratio) are in favor of prolonged weathering and at least second-cycle origin of the MSC Abu Madi sediments. The mutually correspondent elemental ratios (e.g., Al2O3/TiO2, K2O/Na2O, Zr/Hf, Rb/Sr, Cr/Zr, and Cr/Th) and uniform weathering trends are indicatives for a similar provenance of the pre-MSC Qawasim and MSC Abu Madi sediments. Rare earth element (REE) distribution reveals a significant enrichment in LREE, depletion in HREE, relatively high (La/Yb)N (mean > 9), low (Gd/Yb)N (mean < 2) and a pronounced negative Eu anomaly (mean∼0.75) in the studied Messinian facies, characteristics of upper continental sources of mainly felsic to intermediate rock affiliations. Provenance proxy ratios (e.g., Al/Ti, La/Sc, Th/Sc, La/Co and Eu/Eu*) along with the low concentration of transition trace elements (Cr, Ni, Co, Ni) are effectively ruling out the contribution from mafic and ultramafic rocks. The investigated Messinian sedimentary facies have similar passive margin geotectonic setting and their source rocks were originated in a continental collision tectonic setting that lasted from Late Cretaceous to Oligo-Miocene time. This is confirmed by the Nb/Ta, Zr/Sm ratios coupled with the pronounced Nb, Ta, P, Ti anomalies and enrichments in Pb and U relative to primitive mantle typical of subduction zone environment. The petrographical and geochemical results suggest the MSC Abu Madi sediments to have been eroded and recycled from the older pre-MSC Qawasim sediments by gravity-flow processes and fluvial channels prior to redeposition as incised-valley-fills during the late stage of the MSC. The geochemical paleoenvironmental indicators such as C-value, Sr/Cu and Sr/Ba confirm arid-dry climatic conditions during the onset of the MSC consistent with the Mediterranean desiccation. These indicators also depict a transition from freshwater to relatively normal salinity conditions during the late stage of the MSC. Geochemical results presented in this study support the retrogradational depositional infill of the Messinian incised valleys in the Nile Delta, thus confirming an incipient rise in the Mediterranean Sea level prior to the major Zanclean flooding.

Constraints on the bioavailability of trace elements to terrestrial fauna at mining and smelting sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pastorok, R.; Schoof, R.; LaTier, A.

1995-12-31

At mining and smelting sites, the bioavailability of waste-related trace elements to terrestrial wildlife is limited by mineralogy of the waste material and the geochemistry of the waste-soil mixture. For example, encapsulation of trace elements in inert mineral matrices limits the assimilation of particle-associated trace elements that are ingested by wildlife. The bioavailability of arsenic, cadmium, copper, lead, silver, and zinc at mining and smelting sites in Oklahoma and Montana was evaluated based on analysis of waste material, soil chemistry, and concentrations of trace elements in whole-body samples of key food web species. Concentrations of trace elements were generally elevatedmore » relative to reference area values for selected species of vegetation, insects, spiders, and small mammals. Soil-to-tissue bioconcentration factors derived from field data at these sites were generally low (< 1), with the exception of cadmium in vegetation. For all of the trace elements evaluated, wildlife exposure models indicate that the potential for transfer of contaminants to wildlife species of public concern and high trophic-level predators is limited. Moreover, laboratory feeding experiments conducted with cadmium and lead indicate that the assimilation of waste-related trace elements by mammals is relatively low (24--47 percent for lead in blood and bone; 22--44 percent for cadmium in kidney). The relatively low bioavailability of trace elements at mining and smelting sites should be considered when estimating exposure of ecological receptors and when deriving soil cleanup criteria based on measured or modeled ecological risk.« less

Assessment of serum trace elements and electrolytes in children with childhood and atypical autism.

PubMed

Skalny, Anatoly V; Simashkova, Natalia V; Klyushnik, Tatiana P; Grabeklis, Andrei R; Radysh, Ivan V; Skalnaya, Margarita G; Nikonorov, Alexandr A; Tinkov, Alexey A

2017-09-01

The existing data demonstrate a significant interrelation between ASD and essential and toxic trace elements status of the organism. However, data on trace element homeostasis in particular ASD forms are insufficient. Therefore, the objective of the present study was to assess the level of trace elements and electrolytes in serum of children with childhood and atypical autism. A total of 48 children with ASD (24 with childhood and 24 with atypical autism) and age- and sex-adjusted controls were examined. Serum trace elements and electrolytes were assessed using inductively-coupled plasma mass spectrometry. The obtained data demonstrate that children with ASD unspecified are characterized by significantly lower Ni, Cr, and Se levels as compared to the age- and sex-matched controls. At the same time, significantly decreased serum Ni and Se concentrations were detected in patients with childhood autism. In turn, children with atypical autism were characterized by more variable serum trace element spectrum. In particular, atypical autism is associated with lower serum Al, As, Ni, Cr, Mn, and Se levels in comparison to the control values. Moreover, Al and Mn concentration in this group was also lower than that in childhood autism patients. Generally, the obtained data demonstrate lower levels of both essential and toxic trace elements in atypical autism group, being indicative of profound alteration of trace elements metabolism. However, further detailed metabolic studies are required to reveal critical differences in metabolic pathways being responsible for difference in trace element status and clinical course of the disease. Copyright © 2016 Elsevier GmbH. All rights reserved.

Investigation of the Thermal Stability of Nd(x)Sc(y)Zr(1-x-y)O(2-δ) Materials Proposed for Inert Matrix Fuel Applications.

PubMed

Hayes, John R; Grosvenor, Andrew P; Saoudi, Mouna

2016-02-01

Inert matrix fuels (IMF) consist of transuranic elements (i.e., Pu, Am, Np, Cm) embedded in a neutron transparent (inert) matrix and can be used to "burn up" (transmute) these elements in current or Generation IV nuclear reactors. Yttria-stabilized zirconia has been extensively studied for IMF applications, but the low thermal conductivity of this material limits its usefulness. Other elements can be used to stabilize the cubic zirconia structure, and the thermal conductivity of the fuel can be increased through the use of a lighter stabilizing element. To this end, a series of Nd(x)Sc(y)Zr(1-x-y)O(2-δ) materials has been synthesized via a co-precipitation reaction and characterized by multiple techniques (Nd was used as a surrogate for Am). The long-range and local structures of these materials were studied using powder X-ray diffraction, scanning electron microscopy, and X-ray absorption spectroscopy. Additionally, the stability of these materials over a range of temperatures has been studied by annealing the materials at 1100 and 1400 °C. It was shown that the Nd(x)Sc(y)Zr(1-x-y)O(2-δ) materials maintained a single cubic phase upon annealing at high temperatures only when both Nd and Sc were present with y ≥ 0.10 and x + y > 0.15.

[Determination of Trace Elements in Marine Cetaceans by ICP-MS and Health Risk Assessment].

PubMed

Ding, Yu-long; Ning, Xi; Gui, Duan; Mo, Hui; Li, Yu-sen; Wu, Yu-ping

2015-09-01

The liver, kidney and muscle samples from seven cetaceans were digested by microwave digestion, and trace elements amounts of V, Cd, Cu, Zn, As, Cr, Ni, Mn, Se, Hg and Pb were determined by inductively coupled plasma mass spectrometry (ICP-MS), and the health risk assessment for Zn, Cu, Cd, Hg, Se in the liver was conducted. The results of international lobster hepatopancreas standard (TORT-2) showed acceptable agreement with the certified values, and the relative standard deviation (RSD) of eleven kinds of trace elements were less than 3.54%, showing that the method is suitable for the determination of trace elements in cetaceans. The experimental results indicated that different tissues and organs of the dolphins had different trace elements, presenting the tissue specificity. There is a certain inter-species difference among different dolphins about the bioaccumulation ability of the trace elements. The distribution of trace elements in whales presented a certain regularity: the contents of most elements in liver, kidney were much higher than the contents of muscle tissues, Cu, Mn, Hg, Se, and Zn exhibit the higher concentrations in liver, while Cd was mainly accumulated in kidney. And according to the health risk assessment in liver, the exceeding standardrate of selenium and copper in seven kinds of whales was 100%, suggesting that these whales were suffering the contamination of trace elements. The experimental results is instructive to the study of trace elements in cetaceans, while this is the first report for the concentrations in organs of Striped dolphin, Bottlenose dolphin, Fraser's Dolphin and Risso's dolphin in China, it may provide us valuable data for the conservation of cetaceans.

Effect of Multiple Alloying Elements on the Glass-Forming Ability, Thermal Stability, and Crystallization Behavior of Zr-Based Alloys

NASA Astrophysics Data System (ADS)

Bazlov, A. I.; Tsarkov, A. A.; Ketov, S. V.; Suryanarayana, C.; Louzguine-Luzgin, D. V.

2018-02-01

Effect of multiple alloying elements on the glass-forming ability, thermal stability, and crystallization behavior of Zr-based glass-forming alloys were studied in the present work. We investigated the effect of complete or partial substitution of Ti and Ni with similar early and late transition metals, respectively, on the glass-forming ability and crystallization behavior of the Zr50Ti10Cu20Ni10Al10 alloy. Poor correlation was observed between different parameters indicating the glass-forming ability and the critical size of the obtained glassy samples. Importance of the width of the crystallization interval is emphasized. The kinetics of primary crystallization, i.e., the rate of nucleation and rate of growth of the nuclei of primary crystals is very different from that of the eutectic alloys. Thus, it is difficult to estimate the glass-forming ability only on the basis of the empirical parameters not taking into account the crystallization behavior and the crystallization interval.

Selected elements in major minerals from bituminous coal as determined by INAA: Implications for removing environmentally sensitive elements from coal

USGS Publications Warehouse

Palmer, C.A.; Lyons, P.C.

1996-01-01

The four most abundant minerals generally found in Euramerican bituminous coals are quartz, kaolinite, illite and pyrite. These four minerals were isolated by density separation and handpicking from bituminous coal samples collected in the Ruhr Basin, Germany and the Appalachian basin, U.S.A. Trace-element concentrations of relatively pure (??? 99+%) separates of major minerals from these coals were determined directly by using instrumental neutron activation analysis (INAA). As expected, quartz contributes little to the trace-element mass balance. Illite generally has higher trace-element concentrations than kaolinite, but, for the concentrates analyzed in this study, Hf, Ta, W, Th and U are in lower concentrations in illite than in kaolinite. Pyrite has higher concentrations of chalcophile elements (e.g., As and Se) and is considerably lower in lithophile elements as compared to kaolinite and illite. Our study provides a direct and sensitive method of determining trace-element relationships with minerals in coal. Mass-balance calculations suggest that the trace-element content of coal can be explained mainly by three major minerals: pyrite, kaolinite and illite. This conclusion indicates that the size and textural relationships of these major coal minerals may be a more important consideration as to whether coal cleaning can effectively remove the most environmentally sensitive trace elements in coal than what trace minerals are present.

Origin and distribution of trace elements in high-elevation precipitation in southern China.

PubMed

Zhou, Jie; Wang, Yan; Yue, Taixing; Li, Yuhua; Wai, Ka-Ming; Wang, Wenxing

2012-09-01

During a 2009 investigation of the transport and deposition of trace elements in southern China, 37 event-based precipitation samples were collected at an observatory on Mount Heng, China (1,269 m asl). Concentrations of trace elements were analyzed using inductively coupled plasma-mass spectrometry and the wet deposition fluxes were established. A combination of techniques including enrichment factor analysis, principal component analysis, and back trajectory models were used to identify pollutant sources. Trace element concentrations at Mount Heng were among the highest with respect to measured values reported elsewhere. All elements were of non-marine origin. The elements Pb, As, Cu, Se, and Cd were anthropogenic, while Fe, Cr, V, Ba, Mn, and Ni were of mixed crustal/anthropogenic origin. The crustal and anthropogenic contributions of trace elements were 12.8 % (0.9 ~ 17.4 %) and 87.2 % (82.6 ~ 99.1 %), with the maximum crustal fraction being 17.4 % for Fe. Coal combustion, soil and road dust, metallurgical processes, and industrial activities contributed to the element composition. Summit precipitation events were primarily distant in origin. Medium- to long-range transport of trace elements from the Yangtze River Delta and northern China played an important role in wet deposition at Mount Heng, while air masses from south or southeast of the station were generally low in trace element concentrations.

Trends in Trace Element Fractionation Between Foraminiferal Species and the Role of Biomineralization

NASA Astrophysics Data System (ADS)

Reichart, G. J.; Nooijer, L. D.; Geerken, E.; Mezger, E.; van Dijk, I. V.; Daemmer, L. K.

2017-12-01

Reconstructions of past climate and environments are largely based on stable isotopes and trace element concentrations measured on fossil foraminiferal calcite. Their element and isotope composition roughly reflects seawater composition and physical conditions, which in turn, are related to paleoceanographic parameters. More recently, attempts are being made to infer ranges in environmental parameters using the observed differences in the composition within individual tests. Remarkably, inter-species differences in trace element incorporation are well-correlated over a wide range of environmental conditions. This is particularly remarkable knowing that different environmental factors influence incorporation of these elements at various magnitudes. Most likely the complex biomineralization of foraminifera potentially offsets trace elements similarly at all these scales and also between different species. This suggests that at least parts of the mechanisms underlying foraminiferal biomineralization are similar for all species, which in turn provides important clues on the cellular mechanisms operating during calcification. Moreover, the systematics in trace element partitioning between species could potentially provide important clues for unravelling past changes in trace element composition of the ancient ocean.

Hydrogen incorporation and charge balance in natural zircon

NASA Astrophysics Data System (ADS)

De Hoog, J. C. M.; Lissenberg, C. J.; Brooker, R. A.; Hinton, R.; Trail, D.; Hellebrand, E.

2014-09-01

The water and trace element contents of natural igneous zircons were determined to constrain the mechanism of hydrogen incorporation. The low radiation-damage zircons were derived from Fe-Ti oxide gabbros from the Vema Fracture Zone (11°N, Mid-Atlantic Ridge). They contain up to 1212 ppmw H2O, 1.9 wt.% Y2O3 and 0.6 wt.% P2O5 and are generally strongly zoned. REE + Y are partially charge-balanced by P (Y, REE3+ + P5+ = Zr4+ + Si4+), but a large REE excess is present. On an atomic basis, this excess is closely approximated by the amount of H present in the zircons. We therefore conclude that H is incorporated by a charge-balance mechanism (H+ + REE3+ = Zr4+). This interpretation is consistent with FTIR data of the Vema zircons, which shows a strongly polarised main absorption band at ca. 3100 cm-1, similar to experimentally grown Lu-doped hydrous zircon. The size of this 3100 cm-1 band scales with H and REE contents. Apart from a small overlapping band at 3200 cm-1, no other absorption bands are visible, indicating that a hydrogrossular-type exchange mechanism does not appear to be operating in these zircons. Because of charge-balanced uptake of H, P and REE in zircon, the partitioning of these elements into zircon is dependent on each of their concentrations. For instance, DREEzrc/melt increases with increasing H and P contents of the melt, whereas DHzrc/melt increases with increasing REE content but decreases with increasing P content. In addition, H-P-REE systematics of sector zoning indicate kinetic effects may play an important role. Hence, using H in zircon to determine the water content of melts is problematic, and REE partitioning studies need to take into account P and H2O contents of the melt.

Charnockites and granites of the western Adirondacks, New York, USA: a differentiated A-type suite

USGS Publications Warehouse

Whitney, P.R.

1992-01-01

Granitic rocks in the west-central Adirondack Highlands of New York State include both relatively homogeneous charnockitic and hornblende granitic gneisses (CG), that occur in thick stratiform bodies and elliptical domes, and heterogeneous leucogneisses (LG), that commonly are interlayered with metasedimentary rocks. Major- and trace-element geochemical analyses were obtained for 115 samples, including both types of granitoids. Data for CG fail to show the presence of more than one distinct group based on composition. Most of the variance within the CG sample population is consistent with magmatic differentiation combined with incomplete separation of early crystals of alkali feldspar, plagioclase, and pyroxenes or amphibole from the residual liquid. Ti, Fe, Mg, Ca, P, Sr, Ba, and Zr decrease with increasing silica, while Rb and K increase. Within CG, the distinction between charnockitic (orthopyroxene-bearing) and granitic gneisses is correlated with bulk chemistry. The charnockites are consistently more mafic than the hornblende granitic gneisses, although forming a continuum with them. The leucogneisses, while generally more felsic than the charnockites and granitic gneisses, are otherwise geochemically similar to them. The data are consistent with the LG suite being an evolved extrusive equivalent of the intrusive CG suite. Both CG and LG suites are metaluminous to mildly peraluminous and display an A-type geochemical signature, enriched in Fe, K, Ce, Y, Nb, Zr, and Ga and depleted in Ca, Mg, and Sr relative to I- and S-type granites. Rare earth element patterns show moderate LREE enrichment and a negative Eu anomaly throughout the suite. The geochemical data suggest an origin by partial melting of biotite- and plagioclase-rich crustal rocks. Emplacement occurred in an anorogenic or post-collisional tectonic setting, probably at relatively shallow depths. Deformation and granulite-facies metamorphism with some partial melting followed during the Ottawan phase of the Grenville Orogeny, yielding the present migmatitic granitic and charnockitic gneisses. ?? 1992.

Responses of trace elements to aerobic maximal exercise in elite sportsmen.

PubMed

Otag, Aynur; Hazar, Muhsin; Otag, Ilhan; Gürkan, Alper Cenk; Okan, Ilyas

2014-02-21

Trace elements are chemical elements needed in minute quantities for the proper growth, development, and physiology of the organism. In biochemistry, a trace element is also referred to as a micronutrient. Trace elements, such as nickel, cadmium, aluminum, silver, chromium, molybdenum, germanium, tin, titanium, tungsten, scandium, are found naturally in the environment and human exposure derives from a variety of sources, including air, drinking water and food. The Purpose of this study was investigated the effect of aerobic maximal intensity endurance exercise on serum trace elements as well-trained individuals of 28 wrestlers (age (year) 19.64±1.13, weight (Kg) 70.07 ± 15.69, height (cm) 176.97 ± 6.69) during and after a 2000 meter Ergometer test protocol was used to perform aerobic (75 %) maximal endurance exercise. Trace element serum levels were analyzed from blood samples taken before, immediately after and one hour after the exercise. While an increase was detected in Chromium (Cr), Nickel (Ni), Molybdenum (Mo) and Titanium (Ti) serum levels immediately after the exercise, a decrease was detected in Aluminum (Al), Scandium (Sc) and Tungsten (W) serum levels. Except for aluminum, the trace elements we worked on showed statistically meaningful responses (P < 0.05 and P < 0.001). According to the responses of trace elements to the exercise showed us the selection and application of the convenient sport is important not only in terms of sportsman performance but also in terms of future healthy life plans and clinically.

Petrogenesis and origin of the Upper Jurassic-Lower Cretaceous magmatism in Central High Atlas (Morocco): Major, trace element and isotopic (Sr-Nd) constraints

NASA Astrophysics Data System (ADS)

Essaifi, Abderrahim; Zayane, Rachid

2018-01-01

During an uplift phase, which lasted ca. 40 Ma, from the Late Jurassic (165 Ma) to the Early Cretaceous (125 Ma), transitional to moderately alkaline magmatic series were emplaced in the Central High Atlas. The corresponding magmatic products include basaltic lava flows erupted within wide synclines and intrusive complexes composed of layered mafic intrusions and monzonitic to syenitic dykes emplaced along narrow anticlinal ridges. The igneous rock sequence within the intrusive complexes is composed of troctolites, olivine-gabbros, oxide-gabbros, monzonites and syenites. The chemical compositions of the various intrusive rocks can be accounted for by crystal accumulation, fractional crystallization and post-magmatic remobilization. The evolution from the troctolites to the syenites was mainly controlled by a fractional crystallization process marked by early fractionation of olivine, plagioclase and clinopyroxene, followed by separation of biotite, amphibole, apatite, and Ti-magnetite. Hydrothermal activity associated with emplacement of the intrusions within the Jurassic limestones modified the elemental and the Sr isotopic composition of the hydrothermally altered rocks In particular the monzonitic to syenitic dykes underwent an alkali metasomatism marked by depletion in K and Rb and enrichment in Na and Sr. As a result, their Sr isotopic composition was shifted towards higher initial Sr isotopic ratios (0.7067-0.7075) with respect to the associated gabbros (0.7036-0.7046). On the contrary, the Nd isotopic compositions were preserved from isotope exchange with the limestones and vary in a similar range to those of the gabbros (+1.6 < εNdi < +4.1). The isotopic and the trace element ratios of the uncontaminated samples were used to constrain the source characteristics of this magmatism. The Sr-Nd isotopic data and the incompatible element ratios (e.g. La/Nb, Zr/Nb, Th/U, Ce/Pb) are consistent with generation from an enriched upper mantle similar to an ocean island basalt source. Melting of the subcontinental metasomatized lithosphere is tentatively related to small-scale shallow mantle upwelling and asthenospheric uprise at the triple junction between the western High Atlas, the Middle Atlas and the eastern High Atlas domains during a period of relative tectonic quiescence.

Zirconium, hafnium, and rare earth element partition coefficients for ilmenite and other minerals in high-Ti lunar mare basalts - An experimental study

NASA Technical Reports Server (NTRS)

Mckay, G.; Wagstaff, J.; Yang, S.-R.

1986-01-01

Partition coefficients were determined for Gd, Lu, Hf and Zr among ilmenite, armalcolite, and synthetic high-Ti mare basaltic melts at temperatures from 1122 deg to 1150 deg, and at oxygen fugacities of IW x 10 exp 0.5, by in situ analysis with an electron microprobe, using samples doped to present concentration levels. Coefficients for Zr were also measured for samples containing 600-1600 ppm Zr using this microprobe. In addition, coefficients were determined for Hf and Zr between chromian ulvospinel and melt, for Hf between pigeonite and melt, and for Lu between olivine and melt by microprobe analysis of samples doped to present levels. Values measured using the microprobe were in agreement with the values measured by analyzing mineral separates from the same run products by isotope dilution. Coefficient values for ilmenite are less than 0.01 for the LREE, are around 0.1 for the HREE, and are several times greater than this for Zr and Hf.

Assessing the risks of trace elements in environmental materials under selected greenhouse vegetable production systems of China.

PubMed

Chen, Yong; Huang, Biao; Hu, Wenyou; Weindorf, David C; Liu, Xiaoxiao; Niedermann, Silvana

2014-02-01

The risk assessment of trace elements of different environmental media in conventional and organic greenhouse vegetable production systems (CGVPS and OGVPS) can reveal the influence of different farming philosophy on the trace element accumulations and their effects on human health. These provide important basic data for the environmental protection and human health. This paper presents trace element accumulation characteristics of different land uses; reveals the difference of soil trace element accumulation both with and without consideration of background levels; compares the trace element uptake by main vegetables; and assesses the trace element risks of soils, vegetables, waters and agricultural inputs, using two selected greenhouse vegetable systems in Nanjing, China as examples. Results showed that greenhouse vegetable fields contained significant accumulations of Zn in CGVPS relative to rice-wheat rotation fields, open vegetable fields, and geochemical background levels, and this was the case for organic matter in OGVPS. The comparative analysis of the soil medium in two systems with consideration of geochemical background levels and evaluation of the geo-accumulation pollution index achieved a more reasonable comparison and accurate assessment relative to the direct comparison analysis and the evaluation of the Nemerow pollution index, respectively. According to the Chinese food safety standards and the value of the target hazard quotient or hazard index, trace element contents of vegetables were safe for local residents in both systems. However, the spatial distribution of the estimated hazard index for producers still presented certain specific hotspots which may cause potential risk for human health in CGVPS. The water was mainly influenced by nitrogen, especially for CGVPS, while the potential risk of Cd and Cu pollution came from sediments in OGVPS. The main inputs for trace elements were fertilizers which were relatively safe based on relevant standards; but excess application caused trace element accumulations in the environmental media. Copyright © 2013 Elsevier B.V. All rights reserved.

Identification of alpha-enolase as a nuclear DNA-binding protein in the zona fasciculata but not the zona reticularis of the human adrenal cortex.

PubMed

Wang, Weiye; Wang, Lishan; Endoh, Akira; Hummelke, Geoffrey; Hawks, Christina L; Hornsby, Peter J

2005-01-01

In order to establish whether there are differences in DNA-binding proteins between zona fasciculata (ZF) and zona reticularis (ZR) cells of the human adrenal cortex, we prepared nuclear extracts from separated ZF and ZR cells. The formation of DNA-protein complexes was studied using an element in the first intron of the type I and type II 3beta-hydroxysteroid dehydrogenase genes (HSD3B1 and HSD3B2). Using the element in the HSD3B2 gene as a probe, a complex (C1) was formed with extracts from ZF cells but was formed only at a low level with ZR cell extracts. Another pair of complexes (C2/C3) was formed with both ZF and ZR cell extracts. The ZF-specific protein forming C1 was enriched by column chromatography on DEAE-Sepharose and carboxymethyl-Sepharose. Oligonucleotide competition analysis on the enriched fraction gave results consistent with those obtained on the unfractionated material. A further enrichment was brought about by passing the protein over an oligonucleotide affinity column based on the HSD3B2 element. The protein bound to the column was identified as alpha-enolase by mass spectrometry. Although alpha-enolase is a glycolytic enzyme, it binds to specific DNA sequences and has been found to be present in nuclei of various cell types. We performed immunohistochemistry on sections of adult human adrenal cortex and found alpha-enolase to be located in nuclei of ZF cells but to be predominantly cytoplasmic in ZR cells. Transfection of an alpha-enolase expression vector into NCI-H295R human adrenocortical cells increased HSD3B2 promoter activity, suggesting a possible functional role for this protein in regulation of HSD3B2 expression.

Trace elements in natural azurite pigments found in illuminated manuscript leaves investigated by synchrotron x-ray fluorescence and diffraction mapping

NASA Astrophysics Data System (ADS)

Smieska, Louisa M.; Mullett, Ruth; Ferri, Laurent; Woll, Arthur R.

2017-07-01

We present trace-element and composition analysis of azurite pigments in six illuminated manuscript leaves, dating from the thirteenth to sixteenth century, using synchrotron-based, large-area x-ray fluorescence (SR-XRF) and diffraction (SR-XRD) mapping. SR-XRF mapping reveals several trace elements correlated with azurite, including arsenic, zirconium, antimony, barium, and bismuth, that appear in multiple manuscripts but were not always detected by point XRF. Within some manuscript leaves, variations in the concentration of trace elements associated with azurite coincide with distinct regions of the illuminations, suggesting systematic differences in azurite preparation or purification. Variations of the trace element concentrations in azurite are greater among different manuscript leaves than the variations within each individual leaf, suggesting the possibility that such impurities reflect distinct mineralogical/geologic sources. SR-XRD maps collected simultaneously with the SR-XRF maps confirm the identification of azurite regions and are consistent with impurities found in natural mineral sources of azurite. In general, our results suggest the feasibility of using azurite trace element analysis for provenance studies of illuminated manuscript fragments, and demonstrate the value of XRF mapping in non-destructive determination of trace element concentrations within a single pigment.

Co-digestion of manure and industrial waste--The effects of trace element addition.

PubMed

Nordell, Erik; Nilsson, Britt; Nilsson Påledal, Sören; Karisalmi, Kaisa; Moestedt, Jan

2016-01-01

Manure is one of the most common substrates for biogas production. Manure from dairy- and swine animals are often considered to stabilize the biogas process by contributing nutrients and trace elements needed for the biogas process. In this study two lab-scale reactors were used to evaluate the effects of trace element addition during co-digestion of manure from swine- and dairy animals with industrial waste. The substrate used contained high background concentrations of both cobalt and nickel, which are considered to be the most important trace elements. In the reactor receiving additional trace elements, the volatile fatty acids (VFA) concentration was 89% lower than in the control reactor. The lower VFA concentration contributed to a more digested digestate, and thus lower methane emissions in the subsequent storage. Also, the biogas production rate increased with 24% and the biogas production yield with 10%, both as a result of the additional trace elements at high organic loading rates. All in all, even though 50% of the feedstock consisted of manure, trace element addition resulted in multiple positive effects and a more reliable process with stable and high yield. Copyright © 2015 Elsevier Ltd. All rights reserved.

Trace elements in dialysis.

PubMed

Filler, Guido; Felder, Sarah

2014-08-01

In end-stage chronic kidney disease (CKD), pediatric nephrologists must consider the homeostasis of the multiple water-soluble ions that are influenced by renal replacement therapy (RRT). While certain ions such as potassium and calcium are closely monitored, little is known about the handling of trace elements in pediatric dialysis. RRT may lead to accumulation of toxic trace elements, either due to insufficient elimination or due to contamination, or to excessive removal of essential trace elements. However, trace elements are not routinely monitored in dialysis patients and no mechanism for these deficits or toxicities has been established. This review summarizes the handling of trace elements, with particular attention to pediatric data. The best data describe lead and indicate that there is a higher prevalence of elevated lead (Pb, atomic number 82) levels in children on RRT when compared to adults. Lead is particularly toxic in neurodevelopment and lead levels should therefore be monitored. Monitoring of zinc (Zn, atomic number 30) and selenium (Se, atomic number 34) may be indicated in the monitoring of all pediatric dialysis patients to reduce morbidity from deficiency. Prospective studies evaluating the impact of abnormal trace elements and the possible therapeutic value of intervention are required.

Trace-element concentrations in streambed sediment across the conterminous United States

USGS Publications Warehouse

Rice, Karen C.

1999-01-01

Trace-element concentrations in 541 streambed-sediment samples collected from 20 study areas across the conterminous United States were examined as part of the National Water-Quality Assessment Program of the U.S. Geological Survey. Sediment samples were sieved and the <63-μm fraction was retained for determination of total concentrations of trace elements. Aluminum, iron, titanium, and organic carbon were weakly or not at all correlated with the nine trace elements examined:  arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, and zinc. Four different methods of accounting for background/baseline concentrations were examined; however, normalization was not required because field sieving removed most of the background differences between samples. The sum of concentrations of trace elements characteristic of urban settings - copper, mercury, lead, and zinc - was well correlated with population density, nationwide. Median concentrations of seven trace elements (all nine examined except arsenic and selenium) were enriched in samples collected from urban settings relative to agricultural or forested settings. Forty-nine percent of the sites sampled in urban settings had concentrations of one or more trace elements that exceeded levels at which adverse biological effects could occur in aquatic biota.

Effects of Zr and Si on the Glass Forming Ability and Compressive Properties of Ti-Cu-Co-Sn Alloys

NASA Astrophysics Data System (ADS)

Wang, Tan; Wu, Yidong; Si, Jiajia; Hui, Xidong

2015-06-01

To succeed in finding novel Ti-based bulk metallic glasses, which are free from Be, Ni, and noble metallic elements, a comprehensive study was performed on the effects of Zr and Si on the microstructural evolution, glass-forming ability (GFA), and mechanical properties of Ti46Cu44- x Zr x Co7Sn3 ( x = 0, 5, 10, 12.5, and 16 at. pct) and Ti46Cu31.5Zr12.5- x Co7Sn3Si x ( x = 0.5, 1, and 1.5 at. pct) alloys. It is shown that with the increase of Zr, the sequence of phase formation is β-Ti + α-Ti + (Ti, Zr)3Cu4 ⇒ β-Ti + α-Ti + TiCu ⇒ β-Ti + Ti2Cu + glass ⇒ glass ⇒ β-Ti + Ti2Cu + TiCuSn. The quinary Ti-Zr-Cu-Co-Sn alloy with 12.5 pct Zr exhibits the best GFA. The addition of 1 pct Si results in the improvement of the critical size of glassy rods up to 3 mm in diameter. The yield stress and Young's modulus of Z-series alloys increases, and the plastic strain decreases with the addition of Zr. The yield stress and ultimate compression stress of Ti46Zr11.5Cu31.5Co7Sn3Si1 glassy alloy reach 2477.9 and 2623.3 MPa, respectively. It was found that the addition of Si promotes the generation and multiplication of shear bands, resulting in certain plasticity in these kinds of glassy alloys.

Abundance Patterns in S-type AGB Stars: Setting Constraints on Nucleosynthesis and Stellar Evolution Models

NASA Astrophysics Data System (ADS)

Neyskens, P.; van Eck, S.; Plez, B.; Goriely, S.; Siess, L.; Jorissen, A.

2011-09-01

During evolution on the AGB, stars of type S are the first to experience s-process nucleosynthesis and the third dredge-up, and therefore to exhibit s-process signatures in their atmospheres. Their high mass-loss rates (10-7 to 10-6 M⊙/year) make them major contributors to the AGB nucleosynthesis yields at solar metallicity. Precise abundance determinations in S stars are of the utmost importance for constraining e.g. the third dredge-up luminosity and efficiency (which has been only crudely parameterized in current nucleosynthetic models so far). Here, dedicated S-star model atmospheres are used to determine precise abundances of key s-process elements, and to set constraints on nucleosynthesis and stellar evolution models. Special interest is paid to technetium, an element with no stable isotopes. Its detection is considered the best signature that the star effectively populates the thermally-pulsing AGB phase of evolution. The derived Tc/Zr abundances are compared, as a function of the derived [Zr/Fe] overabundances, with AGB stellar model predictions. The [Zr/Fe] overabundances are in good agreement with model predictions, while the Tc/Zr abundances are slightly overpredicted. This discrepancy can help to set better constraints on nucleosynthesis and stellar evolution models of AGB stars.

Chemical diffusion during isobaric degassing of magma

NASA Astrophysics Data System (ADS)

von Aulock, Felix W.; Kennedy, Ben M.; Lavallée, Yan; Henton-de Angelis, Sarah; Oze, Christopher; Morgan, Daniel J.; Clesham, Steve

2014-05-01

During ascent of magma, volatiles exsolve and bubbles form. Volatiles can either escape through a permeable network of bubbles in an open system or be trapped in non-connected pores during closed system degassing. Geochemical studies have shown that in most cases both- open system and closed system degassing take place at the same time. During cooling of the melt, diffusion slows down and eventually diffusional gradients get frozen in, preserving a history of degassing and rehydration during bubble growth, bubble collapse and crystal growth. We present data from experiments in which natural obsidian was degassed at atmospheric pressures at 950ºC over timescales of 3-24h. During bubble growth, a skin formed, at the outer edge of the sample, effectively prohibiting any degassing of its interior. Diffusion gradients were measured across the glass surrounding vesicles, and across this impermeable skin. Water contents were analyzed with synchrotron sourced Fourier transform infrared spectroscopy and several major, minor and trace elements were mapped using synchrotron sourced X-ray fluorescence spectroscopy. The samples show a dimpled surface, as well as signs of oxidation and growth of submicroscopic crystals. Water contents around bubbles decrease in simple heating experiments (from ~0.13 wt. % down to ~0.1 wt. %), whereas slight rehydration of the vesicle wall can be observed when a second, cooler step at 850ºC follows the initial 950ºC. Water gradients towards the outside of the sample decrease linearly to a minimum of ~0.045 wt. %, far below the solubility of water in melts at these temperatures. We mapped the distribution of K, Ca, Fe, Ti, Mn, Rb, Sr, Y and Zr. Especially the trace elements show a decrease towards the outside of the sample, whereas K, Fe, Ca and Ti generally do not show significant partitioning between melt and gas/crystal phase. Several effects could attribute to the distribution of these elements, such as the crystal growth and exchange with atmospheric oxygen, and detailed models of the diffusion of these elements will have to verify the mechanisms of elemental partitioning during degassing Our experiments show that even on a small scale, open system and closed system degassing inherently coexist. This manifests itself in different elemental distribution in the quenched glass. Water distribution gradients can be explained with diffusion during exsolution and rehydration during cooling, however, the surface of the sample is undersaturated in water. Some trace elements follow the same pattern, even though they might not be considered as volatile. Therefore we suggest that chemical gradients may be partially induced by the growth of sub-microscopic crystals and by exchange with the atmosphere. Crystal rich, volatile poor outer skins, as produced in the experiments of this study, have locally drastically increased viscosities and can therefore withstand higher pressures during foaming of the interior of the sample. This self sealing of magma could be an important process on different scales of magma degassing, from bread crust bombs to rising magma in conduits.

Soluble trace elements and total mercury in Arctic Alaskan snow

USGS Publications Warehouse

Snyder-Conn, E.; Garbarino, J.R.; Hoffman, G.L.; Oelkers, A.

1997-01-01

Ultraclean field and laboratory procedures were used to examine trace element concentrations in northern Alaskan snow. Sixteen soluble trace elements and total mercury were determined in snow core samples representing the annual snowfall deposited during the 1993-94 season at two sites in the Prudhoe Bay oil field and nine sites in the Arctic National Wildlife Refuge (Arctic NWR). Results indicate there were two distinct point sources for trace elements in the Prudhoe Bay oil field - a source associated with oil and gas production and a source associated with municipal solid-waste incineration. Soluble trace element concentrations measured in snow from the Arctic NWR resembled concentrations of trace elements measured elsewhere in the Arctic using clean sample-collection and processing techniques and were consistent with deposition resulting from widespread arctic atmospheric contamination. With the exception of elements associated with sea salts, there were no orographic or east-west trends observed in the Arctic NWR data, nor were there any detectable influences from the Prudhoe Bay oil field, probably because of the predominant easterly and northeasterly winds on the North Slope of Alaska. However, regression analysis on latitude suggested significant south-to-north increases in selected trace element concentrations, many of which appear unrelated to the sea salt contribution.

The effects of trace element content on pyrite oxidation rates

NASA Astrophysics Data System (ADS)

Gregory, D. D.; Lyons, T.; Cliff, J. B.; Perea, D. E.; Johnson, A.; Romaniello, S. J.; Large, R. R.

2017-12-01

Pyrite acts as both an important source and sink for many different metals and metalloids in the environment, including many that are toxic. Oxidation of pyrite can release these elements while at the same time producing significant amounts of sulfuric acid. Such issues are common in the vicinity of abandoned mines and smelters, but, as pyrite is a common accessory mineral in many different lithologies, significant pyrite oxidation can occur whenever pyritic rocks are exposed to oxygenated water or the atmosphere. Accelerated exposure to oxygen can occur during deforestation, fracking for petroleum, and construction projects. Geochemical models for pyrite oxidation can help us develop strategies to mitigate these deleterious effects. An important component of these models is an accurate pyrite oxidation rate; however, current pyrite oxidation rates have been determined using relatively pure pyrite. Natural pyrite is rarely pure and has a wide range of trace element concentrations that may affect the oxidation rate. Furthermore, the position of trace elements within the mineral lattice can also affect the oxidation rate. For example, elements such as Ni and Co, which substitute into the pyrite lattice, are thought to stabilize the lattice and thus prevent pyrite oxidation. Alternatively, trace elements that are held within inclusions of other minerals could form a galvanic cell with the surrounding pyrite, thus enhancing pyrite oxidation rates. In this study, we present preliminary analyses from three different pyrite oxidation experiments each using natural pyrite with different trace element compositions. These results show that the pyrite with the highest trace element concentration has approximately an order of magnitude higher oxidation rate compared to the lowest trace element sample. To further elucidate the mechanisms, we employed microanalytical techniques to investigate how the trace elements are held within the pyrite. LA-ICPMS was used to determine the variability of trace element content from the pyrite samples. These data were then used to select areas of interest for NanoSIMS analyses, which in turn was used to select areas for TEM and APT. These analyses show that the trace element content of pyrite can be highly variable, which may significantly affect the rate of pyrite oxidation.

Concentrations of selected trace elements in fish tissue and streambed sediment in the Clark Fork-Pend Oreille and Spokane River basins, Washington, Idaho, and Montana, 1998

USGS Publications Warehouse

Maret, Terry R.; Skinner, K.D.

2000-01-01

Fish tissue and bed sediment samples were collected from 16 stream sites in the Northern Rockies Intermontane Basins study area in 1998 as part of the U.S. Geological Survey National Water-Quality Assessment Program. Bed sediment samples were analyzed for 45 trace elements, and fish livers and sportfish fillets were analyzed for 22 elements to characterize the occurrence and distribution of these elements in relation to stream characteristics and land use activities. Nine trace elements of environmental concern—arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, and zinc—were detected in bed sediment, but not all of these elements were detected in fish tissue. Trace-element concentrations were highest in bed sediment samples collected at sites downstream from significant natural mineral deposits and (or) mining activities. Arsenic, cadmium, copper, lead, mercury, and zinc in bed sediment at some sites were elevated relative to national median concentrations, and some concentrations were at levels that can adversely affect aquatic biota. Although trace-element concentrations in bed sediment exceeded various guidelines, no concentrations in sportfish fillets exceeded U.S. Environmental Protection Agency screening values for the protection of human health. Correlations between most trace-element concentrations in bed sediment and fish tissue (liver and fillet) were not significant (r0.05). Concentrations of arsenic, cadmium, copper, lead, mercury, nickel, selenium, and zinc in bed sediment were significantly correlated (r=0.53 to 0.88, p2=0.95 and 0.99, p<0.001) that corresponded to trace-element enrichment categories. These strong relations warrant further study using mine density as an explanatory variable to predict trace-element concentrations in bed sediment.

Trace Elements in Marine Sediment and Organisms in the Gulf of Thailand

PubMed Central

Worakhunpiset, Suwalee

2018-01-01

This review summarizes the findings from studies of trace element levels in marine sediment and organisms in the Gulf of Thailand. Spatial and temporal variations in trace element concentrations were observed. Although trace element contamination levels were low, the increased urbanization and agricultural and industrial activities may adversely affect ecosystems and human health. The periodic monitoring of marine environments is recommended in order to minimize human health risks from the consumption of contaminated marine organisms. PMID:29677146

LA-ICP-MS trace element mapping: insights into the crystallisation history of a metamorphic garnet population

NASA Astrophysics Data System (ADS)

George, Freya; Gaidies, Fred

2017-04-01

In comparison to our understanding of major element zoning, relatively little is known about the incorporation of trace elements into metamorphic garnet. Given their extremely slow diffusivities and sensitivity to changing mineral assemblages, the analysis of the distribution of trace elements in garnet has the potential to yield a wealth of information pertaining to interfacial attachment mechanisms during garnet crystallisation, the mobility of trace elements in both garnet and the matrix, and trace element geochronology. Due to advances in the spatial resolution and analytical precision of modern microbeam techniques, small-scale trace element variations can increasingly be documented and used to inform models of metamorphic crystallisation. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in particular, can be used to rapidly quantify a wide range of elemental masses as a series of laser rasters, producing large volumes of spatially constrained trace element data. In this study, we present LA-ICP-MS maps of trace element concentrations from numerous centrally-sectioned garnets representative of the crystal size-distribution of a single sample's population. The study sample originates from the garnet-grade Barrovian zone of the Lesser Himalayan Sequence in Sikkim, northeast India, and has been shown to have crystallised garnet within a single assemblage between 515 ˚C and 565˚C, with no evidence for accessory phase reaction over the duration of garnet growth. Previous models have indicated that the duration of garnet crystallisation was extremely rapid (<1 Myr), with negligible diffusional homogenisation of major divalent cations. Consequently, the trace element record likely documents the primary zonation generated during garnet growth. In spite of straightforward (i.e. concentrically-zoned) major element garnet zonation, trace elements maps are characterised by significant complexity and variability. Y and the heavy rare earth elements are strongly enriched in crystal cores, where there is overprinting of the observed internal fabric, and exhibit numerous concentric annuli towards crystal rims. Conversely, the medium rare earth elements (e.g. Gd, Eu and Sm) exhibit bowl-shaped zoning from core to rim, with no annuli, and core and rim compositions of the medium rare earth elements are the same throughout the population within crystals of differing size. Cr exhibits pronounced spiral zoning, and the average Cr content increases towards garnet rims. In all cases, spirals are centered on the geometric core of the crystals. These LA-ICP-MS maps highlight the complexity of garnet growth over a single prograde event, and indicate that there is still much to be learnt from the analysis of garnet using ever-improving analytical methods. We explore the potential causes of the variations in the distribution of trace elements in garnet, and assess how these zoning patterns may be used to refine our understanding of the intricacies of garnet crystallisation and the spatial and temporal degree of trace element equilibration during metamorphism.

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.

Trace elements in Mediterranean seagrasses and macroalgae. A review.

PubMed

Bonanno, Giuseppe; Orlando-Bonaca, Martina

2018-03-15

This review investigates the current state of knowledge on the levels of the main essential and non-essential trace elements in Mediterranean vascular plants and macroalgae. The research focuses also on the so far known effects of high element concentrations on these marine organisms. The possible use of plants and algae as bioindicators of marine pollution is discussed as well. The presence of trace elements is overall well known in all five Mediterranean vascular plants, whereas current studies investigated element concentrations in only c. 5.0% of all native Mediterranean macroalgae. Although seagrasses and macroalgae can generally accumulate and tolerate high concentrations of trace elements, phytotoxic levels are still not clearly identified for both groups of organisms. Moreover, although the high accumulation of trace elements in seagrasses and macroalgae is considered as a significant risk for the associated food webs, the real magnitude of this risk has not been adequately investigated yet. The current research provides enough scientific evidence that seagrasses and macroalgae may act as effective bioindicators, especially the former for trace elements in sediments, and the latter in seawater. The combined use of seagrasses and macroalgae as bioindicators still lacks validated protocols, whose application should be strongly encouraged to biomonitor exhaustively the presence of trace elements in the abiotic and biotic components of coastal ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

Visualizing trace element distribution in quartz using cathodoluminescence, electron microprobe, and laser ablation-inductively coupled plasma-mass spectrometry

USGS Publications Warehouse

Rusk, Brian; Koenig, Alan; Lowers, Heather

2011-01-01

Cathodoluminescent (CL) textures in quartz reveal successive histories of the physical and chemical fluctuations that accompany crystal growth. Such CL textures reflect trace element concentration variations that can be mapped by electron microprobe or laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Trace element maps in hydrothermal quartz from four different ore deposit types (Carlin-type Au, epithermal Ag, porphyry-Cu, and MVT Pb-Zn) reveal correlations among trace elements and between trace element concentrations and CL textures. The distributions of trace elements reflect variations in the physical and chemical conditions of quartz precipitation. These maps show that Al is the most abundant trace element in hydrothermal quartz. In crystals grown at temperatures below 300 °C, Al concentrations may vary by up to two orders of magnitude between adjacent growth zones, with no evidence for diffusion. The monovalent cations Li, Na, and K, where detectable, always correlate with Al, with Li being the most abundant of the three. In most samples, Al is more abundant than the combined total of the monovalent cations; however, in the MVT sample, molar Al/Li ratios are ~0.8. Antimony is present in concentrations up to ~120 ppm in epithermal quartz (~200–300 °C), but is not detectable in MVT, Carlin, or porphyry-Cu quartz. Concentrations of Sb do not correlate consistently with those of other trace elements or with CL textures. Titanium is only abundant enough to be mapped in quartz from porphyry-type ore deposits that precipitate at temperatures above ~400 °C. In such quartz, Ti concentration correlates positively with CL intensity, suggesting a causative relationship. In contrast, in quartz from other deposit types, there is no consistent correlation between concentrations of any trace element and CL intensity fluctuations.

Trace element profiles in modern horse molar enamel as tracers of seasonality: Evidence from micro-XRF, LA-ICP-MS and stable isotope analysis

NASA Astrophysics Data System (ADS)

de Winter, Niels; Goderis, Steven; van Malderen, Stijn; Vanhaecke, Frank; Claeys, Philippe

2016-04-01

A combination of laboratory micro-X-ray Fluorescence (μXRF) and stable carbon and oxygen isotope analysis shows that trace element profiles from modern horse molars reveal a seasonal pattern that co-varies with seasonality in the oxygen isotope records of enamel carbonate from the same teeth. A combination of six cheek teeth (premolars and molars) from the same individual yields a seasonal isotope and trace element record of approximately three years recorded during the growth of the molars. This record shows that reproducible measurements of various trace element ratios (e.g., Sr/Ca, Zn/Ca, Fe/Ca, K/Ca and S/Ca) lag the seasonal pattern in oxygen isotope records by 2-3 months. Laser Ablation-ICP-Mass Spectrometry (LA-ICP-MS) analysis on a cross-section of the first molar of the same individual is compared to the bench-top tube-excitation μXRF results to test the robustness of the measurements and to compare both methods. Furthermore, trace element (e.g. Sr, Zn, Mg & Ba) profiles perpendicular to the growth direction of the same tooth, as well as profiles parallel to the growth direction are measured with LA-ICP-MS and μXRF to study the internal distribution of trace element ratios in two dimensions. Results of this extensive complementary line-scanning procedure shows the robustness of state of the art laboratory micro-XRF scanning for the measurement of trace elements in bioapatite. The comparison highlights the advantages and disadvantages of both methods for trace element analysis and illustrates their complementarity. Results of internal variation within the teeth shed light on the origins of trace elements in mammal teeth and their potential use for paleo-environmental reconstruction.

Traffic-related trace elements in soils along six highway segments on the Tibetan Plateau: Influence factors and spatial variation.

PubMed

Wang, Guanxing; Zeng, Chen; Zhang, Fan; Zhang, Yili; Scott, Christopher A; Yan, Xuedong

2017-03-01

The accumulation of traffic-related trace elements in soil as the result of anthropogenic activities raises serious concerns about environmental pollution and public health. Traffic is the main source of trace elements in roadside soil on the Tibetan Plateau, an area otherwise devoid of industrial emissions. Indeed, the rapid development of tourism and transportation in this region means it is becoming increasingly important to identify the accumulation levels, influence distance, spatial distribution, and other relevant factors influencing trace elements. In this study, 229 soil samples along six segments of the major transportation routes on the Tibetan Plateau (highways G214, S308, and G109), were collected for analysis of eight trace elements (Cr, Co, Ni, As, Cu, Zn, Cd, and Pb). The results of statistical analyses showed that of the eight trace elements in soils, Cu, Zn, Cd, and Pb were primarily derived from traffic. The relationship between the trace element accumulation levels and the distance from the roadside followed an exponential decline, with the exception of Segment 3, the only unpaved gravel road studied. In addition, the distance of influence from the roadside varied by trace element and segment, ranging from 16m to 144m. Background values for each segment were different because of soil heterogeneity, while a number of other potential influencing factors (including traffic volume, road surface material, roadside distance, land cover, terrain, and altitude) all had significant effects on trace-element concentrations. Overall, however, concentrations along most of the road segments investigated were at, or below, levels defined as low on the Nemero Synthesis index. Copyright © 2017 Elsevier B.V. All rights reserved.

Evolution of trace elements in the planetary boundary layer in southern China: Effects of dust storms and aerosol-cloud interactions

NASA Astrophysics Data System (ADS)

Li, Tao; Wang, Yan; Zhou, Jie; Wang, Tao; Ding, Aijun; Nie, Wei; Xue, Likun; Wang, Xinfeng; Wang, Wenxing

2017-03-01

Aerosols and cloud water were analyzed at a mountaintop in the planetary boundary layer in southern China during March-May 2009, when two Asian dust storms occurred, to investigate the effects of aerosol-cloud interactions (ACIs) on chemical evolution of atmospheric trace elements. Fe, Al, and Zn predominated in both coarse and fine aerosols, followed by high concentrations of toxic Pb, As, and Cd. Most of these aerosol trace elements, which were affected by dust storms, exhibited various increases in concentrations but consistent decreases in solubility. Zn, Fe, Al, and Pb were the most abundant trace elements in cloud water. The trace element concentrations exhibited logarithmic inverse relationships with the cloud liquid water content and were found highly pH dependent with minimum concentrations at the threshold of pH 5.0. The calculation of Visual MINTEQ model showed that 80.7-96.3% of Fe(II), Zn(II), Pb(II), and Cu(II) existed in divalent free ions, while 71.7% of Fe(III) and 71.5% of Al(III) were complexed by oxalate and fluoride, respectively. ACIs could markedly change the speciation distributions of trace elements in cloud water by pH modification. The in-cloud scavenging of aerosol trace elements likely reached a peak after the first 2-3 h of cloud processing, with scavenging ratios between 0.12 for Cr and 0.57 for Pb. The increases of the trace element solubility (4-33%) were determined in both in-cloud aerosols and postcloud aerosols. These results indicated the significant importance of aerosol-cloud interactions to the evolution of trace elements during the first several cloud condensation/evaporation cycles.

Trace element concentrations in liver of 16 species of cetaceans stranded on Pacific Islands from 1997 through 2013

PubMed Central

Hansen, Angela M. K.; Bryan, Colleen E.; West, Kristi; Jensen, Brenda A.

2016-01-01

The impacts of anthropogenic contaminants on marine ecosystems are a concern worldwide. Anthropogenic activities can enrich trace elements in marine biota to concentrations that may negatively impact organism health. Exposure to elevated concentrations of trace elements is considered a contributing factor in marine mammal population declines. Hawai'i is an increasingly important geographic location for global monitoring, yet trace element concentrations have not been quantified in Hawaiian cetaceans, and there is little trace element data for Pacific cetaceans. This study measured trace elements (Cr, Mn, Cu, Zn, As, Se, Sr, Cd, Sn, Hg, and Pb) in liver of 16 species of cetaceans that stranded on U.S. Pacific Islands from 1997–2013, using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) (n = 31), and direct mercury analysis atomic absorption spectrometry (DMA-AAS) (n = 43). Concentration ranges (µg/g wet mass fraction) for non-essential trace elements such as Cd (0.0031–58.93) and Hg (0.0062–1571.75) were much greater than essential trace elements such as Mn (0.590–17.31) and Zn (14.72–245.38). Differences were found among age classes in Cu, Zn, Hg, and Se concentrations. The highest concentrations of Se, Cd, Sn, Hg, and Pb were found in one adult female false killer whale (Pseudorca crassidens) at concentrations that are known to affect health in marine mammals. The results of this study establish initial trace element concentration ranges for Pacific cetaceans in the Hawaiian Islands region, provide insights into contaminant exposure of these marine mammals, and contribute to a greater understanding of anthropogenic impacts in the Pacific Ocean. PMID:26283019

Trace Element Concentrations in Liver of 16 Species of Cetaceans Stranded on Pacific Islands from 1997 through 2013.

PubMed

Hansen, Angela M K; Bryan, Colleen E; West, Kristi; Jensen, Brenda A

2016-01-01

The impacts of anthropogenic contaminants on marine ecosystems are a concern worldwide. Anthropogenic activities can enrich trace elements in marine biota to concentrations that may negatively impact organism health. Exposure to elevated concentrations of trace elements is considered a contributing factor in marine mammal population declines. Hawai'i is an increasingly important geographic location for global monitoring, yet trace element concentrations have not been quantified in Hawaiian cetaceans, and there is little trace element data for Pacific cetaceans. This study measured trace elements (Cr, Mn, Cu, Zn, As, Se, Sr, Cd, Sn, Hg, and Pb) in liver of 16 species of cetaceans that stranded on U.S. Pacific Islands from 1997 to 2013, using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) (n = 31), and direct mercury analysis atomic absorption spectrometry (DMA-AAS) (n = 43). Concentration ranges (μg/g wet mass fraction) for non-essential trace elements, such as Cd (0.0031-58.93) and Hg (0.0062-1571.75) were much greater than essential trace elements, such as Mn (0.590-17.31) and Zn (14.72-245.38). Differences were found among age classes in Cu, Zn, Hg, and Se concentrations. The highest concentrations of Se, Cd, Sn, Hg, and Pb were found in one adult female false killer whale (Pseudorca crassidens) at concentrations that are known to affect health in marine mammals. The results of this study establish initial trace element concentration ranges for Pacific cetaceans in the Hawaiian Islands region, provide insights into contaminant exposure of these marine mammals, and contribute to a greater understanding of anthropogenic impacts in the Pacific Ocean.

Trace Elements Affect Methanogenic Activity and Diversity in Enrichments from Subsurface Coal Bed Produced Water

PubMed Central

Ünal, Burcu; Perry, Verlin Ryan; Sheth, Mili; Gomez-Alvarez, Vicente; Chin, Kuk-Jeong; Nüsslein, Klaus

2012-01-01

Microbial methane from coal beds accounts for a significant and growing percentage of natural gas worldwide. Our knowledge of physical and geochemical factors regulating methanogenesis is still in its infancy. We hypothesized that in these closed systems, trace elements (as micronutrients) are a limiting factor for methanogenic growth and activity. Trace elements are essential components of enzymes or cofactors of metabolic pathways associated with methanogenesis. This study examined the effects of eight trace elements (iron, nickel, cobalt, molybdenum, zinc, manganese, boron, and copper) on methane production, on mcrA transcript levels, and on methanogenic community structure in enrichment cultures obtained from coal bed methane (CBM) well produced water samples from the Powder River Basin, Wyoming. Methane production was shown to be limited both by a lack of additional trace elements as well as by the addition of an overly concentrated trace element mixture. Addition of trace elements at concentrations optimized for standard media enhanced methane production by 37%. After 7 days of incubation, the levels of mcrA transcripts in enrichment cultures with trace element amendment were much higher than in cultures without amendment. Transcript levels of mcrA correlated positively with elevated rates of methane production in supplemented enrichments (R2 = 0.95). Metabolically active methanogens, identified by clone sequences of mcrA mRNA retrieved from enrichment cultures, were closely related to Methanobacterium subterraneum and Methanobacterium formicicum. Enrichment cultures were dominated by M. subterraneum and had slightly higher predicted methanogenic richness, but less diversity than enrichment cultures without amendments. These results suggest that varying concentrations of trace elements in produced water from different subsurface coal wells may cause changing levels of CBM production and alter the composition of the active methanogenic community. PMID:22590465

Petrography and geochemistry of modern river sediments in an equatorial environment (Rwenzori Mountains and Albertine rift, Uganda) - Implications for weathering and provenance

NASA Astrophysics Data System (ADS)

Schneider, Sandra; Hornung, Jens; Hinderer, Matthias; Garzanti, Eduardo

2016-05-01

In hot-humid equatorial climate chemical weathering may be so strong that provenance signatures may be largely lost and even detritus derived from crystalline basement rocks reduced to quartzose sand. We tested this hypothesis in western Uganda, where stable plateau areas contrast with the active tectonic setting of the Albertine Rift (western branch of the East African Rift System, EARS), culminating in the strongly exhumed fault block of the > 5000 m high Rwenzori Mountains. In this setting, sediments derived from similar types of basement rocks including gneiss, schist, amphibolite, metasediments and granites can be traced from rapidly eroding high-altitude areas to low-altitude areas undergoing prolonged weathering. Sand and mud carried by 51 rivers overall in these two contrasting landscapes were sampled to study how and to what extent detrital modes are modified by the selective loss of unstable detrital minerals. Sediments generated in the high-relief Rwenzori Mountains show abundant feldspar (up to 32%) and rock fragments (up to 52%), which together with low SiO2/Al2O3 ratio and composition close to the Upper Continental Crust (UCC standard) reflect erosion in weathering-limited conditions. In the central Rwenzoris, low Th/Sc and Zr/Sc ratios, weak negative Eu anomaly, lower LaN/YbN values, and heavy-mineral assemblages with hornblende and epidote reflect the lithology of source rocks in the Buganda-Toro-Greenstone Belt. In contrast, sediments produced on the low-relief plateau have quartz content up to 98% and higher SiO2/Al2O3 ratio. Systematic loss of mobile elements is indicated by high chemical weathering indices CIA, PIA and WIP. However, provenance from metamorphic basement rocks is still indicated by heavy-mineral assemblages dominated by epidote and amphibole, whereas provenance from granitic rocks is revealed by high Th/Sc and Zr/Sc ratio, negative Eu anomaly and higher LaN/YbN values. We conclude that first-cycle sediments generated in high-relief areas preserve the original imprint of parent lithologies even in very humid equatorial climate. In low-relief areas, although weathering processes have proceeded over millions of years turning basement-derived detritus into an almost pure quartzose resistate, provenance signals are not erased entirely, and can be still retrieved from the residual heavy-mineral suite and relative abundance of high-field-strength trace elements.

Trace Element Concentrations in Beef Cattle Related to the Breed Aptitude.

PubMed

Pereira, Victor; Carbajales, Paloma; López-Alonso, Marta; Miranda, Marta

2018-02-24

Animal feed has traditionally been supplemented with trace elements at dietary concentrations well above physiological needs. However, environmental concerns have led to calls for better adjustment of mineral supplementation to actual physiological needs and, in this context, consideration of breed-related differences in trace element requirements. The aim of this study was to analyze trace element concentrations in the main breeds used for intensive beef production in northern Spain (Holstein-Friesian [HF], Galician Blonde [GB], and GB × HF cross). Samples of blood, internal organs, and muscle were obtained at slaughter from 10 HF, GB, and GB × HF cross calves in the same feedlot. Overall, trace element concentrations in serum and internal organs were within adequate ranges and did not differ between those of breeds, suggesting that trace mineral supplementation was adequate in all groups. The only exception to this was copper, and hepatic copper concentrations were above adequate levels in all calves. This was particularly evident in the HF calves, and the maximum recommended level for human consumption was exceeded in 90% of these animals. Copper, iron, manganese, selenium, and zinc concentrations in muscle were significantly higher in the HF than those in the GB calves, with intermediate values for the crosses. These breed-related differences in trace element concentrations in the muscle may be related to lower muscle mass and/or higher hepatic activity in the HF (dairy) calves than in GB (beef) calves. As meat is an essential source of highly available trace elements in human diets, breed-related differences in trace element concentrations in meat deserve further investigation.

Trace Elements in Parenteral Nutrition: Considerations for the Prescribing Clinician

PubMed Central

Jin, Jennifer; Mulesa, Leanne; Carrilero Rouillet, Mariana

2017-01-01

Trace elements (TEs) are an essential component of parenteral nutrition (PN). Over the last few decades, there has been increased experience with PN, and with this knowledge more information about the management of trace elements has become available. There is increasing awareness of the effects of deficiencies and toxicities of certain trace elements. Despite this heightened awareness, much is still unknown in terms of trace element monitoring, the accuracy of different assays, and current TE contamination of solutions. The supplementation of TEs is a complex and important part of the PN prescription. Understanding the role of different disease states and the need for reduced or increased doses is essential. Given the heterogeneity of the PN patients, supplementation should be individualized. PMID:28452962

Trace elements in parenteral nutrition: a practical guide for dosage and monitoring for adult patients.

PubMed

Fessler, Theresa A

2013-12-01

Parenteral nutrition (PN) is a life-sustaining therapy for hundreds of thousands of people who have severe impairment of gastrointestinal function. Trace elements are a small but very important part of PN that can be overlooked during busy practice. Serious complications can result from trace element deficiencies and toxicities, and this is especially problematic during times of product shortages. Practical information on parenteral trace element use can be gleaned from case reports, some retrospective studies, and very few randomized controlled trials. A general knowledge of trace element metabolism and excretion, deficiency and toxicity symptoms, products, optimal dosages, and strategies for supplementation, restriction, and monitoring will equip practitioners to provide optimal care for their patients who depend on PN.

Trace Elements in Parenteral Nutrition: Considerations for the Prescribing Clinician.

PubMed

Jin, Jennifer; Mulesa, Leanne; Carrilero Rouillet, Mariana

2017-04-28

Trace elements (TEs) are an essential component of parenteral nutrition (PN). Over the last few decades, there has been increased experience with PN, and with this knowledge more information about the management of trace elements has become available. There is increasing awareness of the effects of deficiencies and toxicities of certain trace elements. Despite this heightened awareness, much is still unknown in terms of trace element monitoring, the accuracy of different assays, and current TE contamination of solutions. The supplementation of TEs is a complex and important part of the PN prescription. Understanding the role of different disease states and the need for reduced or increased doses is essential. Given the heterogeneity of the PN patients, supplementation should be individualized.

Methods for making a porous nuclear fuel element

DOEpatents

Youchison, Dennis L; Williams, Brian E; Benander, Robert E

2014-12-30

Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

Efficient UV-emitting X-ray phosphors: octahedral Zr(PO 4) 6 luminescence centers in potassium hafnium-zirconium phosphates K 2Hf 1- xZr x(PO 4) 2 and KHf 2(1- x) Zr 2 x(PO 4) 3

NASA Astrophysics Data System (ADS)

Torardi, C. C.; Miao, C. R.; Li, J.

2003-02-01

Potassium hafnium-zirconium phosphates, K 2Hf 1- xZr x(PO 4) 2 and KHf 2(1- x) Zr 2 x(PO 4) 3, are broad-band UV-emitting phosphors. At room temperature, they have emission peak maxima at approximately 322 and 305 nm, respectively, under 30 kV peak molybdenum X-ray excitation. Both phosphors demonstrate luminescence efficiencies that make them up to ˜60% as bright as commercially available CaWO 4 Hi-Plus. The solid-state and flux synthesis conditions, and X-ray excited UV luminescence of these two phosphors are discussed. Even though the two compounds have different atomic structures, they contain zirconium in the same active luminescence environment as that found in highly efficient UV-emitting BaHf 1- xZr x(PO 4) 2. All the three materials have hafnium and zirconium in octahedral coordination via oxygen-atom corner sharing with six separate PO 4 tetrahedra. This octahedral Zr(PO 4) 6 moiety appears to be an important structural element for efficient X-ray excited luminescence, as are the edge-sharing octahedral TaO 6 chains for tantalate emission.

Profiles of non-essential trace elements in ewe and goat milk and their yoghurt, Torba yoghurt and whey.

PubMed

Sanal, Hasan; Güler, Zehra; Park, Young W

2011-01-01

The objectives of this study were to determine the profiles of non-essential trace elements in ewes' and goats' milk and manufactured products, such as yoghurt, torba yoghurt and whey, as well as changes in trace element content during Torba yoghurt-making processes. Concentrations of non-essential trace elements in ewe (Awassi) and goat (Damascus) milk and their yoghurt, torba yoghurt and whey were quantitatively determined by simultaneous inductively coupled plasma optical emission spectrometer (ICP-OES), after microwave digestion. Aluminium, antimony, arsenic, boron, beryllium, cadmium, nickel, lead, silver, titanium, thallium and vanadium were determined for both types of milk and their products. Barium was not detected in goats' milk or their products. Among all trace elements, boron was the most abundant and beryllium was least present in milk and the manufactured products. The results showed that goats' and ewes' milk and their manufactured products may be a source of 13 non-essential trace elements.

Geological occurrence response to trace elemental migration in coal liquefaction based on SPSS: take no. 11 coalbed in Antaibao mine for example

NASA Astrophysics Data System (ADS)

Xia, Xiaohong; Qin, Yong; Yang, Weifeng

2013-03-01

Coal liquefaction is an adoptable method to transfer the solid fossil energy into liquid oil in large scale, but the dirty material in which will migrate to different step of liquefaction. The migration rule of some trace elements is response to the react activity of macerals in coal and the geological occurrence of the element nature of itself. In this paper, from the SPSS data correlation analysis and hierarchical clustering dendrogram about the trace elements with macerals respond to coal liquefaction yield, it shows the trace elements in No.11 Antaibao coal seam originated from some of lithophile and sulphophle elements. Correlation coefficient between liquefaction yield of three organic macerals and migration of the elements in liquefaction residue indicated that the lithophile are easy to transfer to residue, while sulphophle are apt to in the liquid products. The activated macerals are response to sulphophle trace elements. The conclusion is useful to the coal blending and environmental effects on coal direct liquefaction.

Variation in Macro and Trace Elements in Progression of Type 2 Diabetes

PubMed Central

2014-01-01

Macro elements are the minerals of which the body needs more amounts and are more important than any other elements. Trace elements constitute a minute part of the living tissues and have various metabolic characteristics and functions. Trace elements participate in tissue and cellular and subcellular functions; these include immune regulation by humoral and cellular mechanisms, nerve conduction, muscle contractions, membrane potential regulations, and mitochondrial activity and enzyme reactions. The status of micronutrients such as iron and vanadium is higher in type 2 diabetes. The calcium, magnesium, sodium, chromium, cobalt, iodine, iron, selenium, manganese, and zinc seem to be low in type 2 diabetes while elements such as potassium and copper have no effect. In this review, we emphasized the status of macro and trace elements in type 2 diabetes and its advantages or disadvantages; this helps to understand the mechanism, progression, and prevention of type 2 diabetes due to the lack and deficiency of different macro and trace elements. PMID:25162051

Intrinsic nanostructure in Zr2-xFe4Si16-y(x = 0.81, y = 6.06)

NASA Astrophysics Data System (ADS)

Smith, G. J.; Simonson, J. W.; Orvis, T.; Marques, C.; Grose, J. E.; Kistner-Morris, J. J.; Wu, L.; Cho, K.; Kim, H.; Tanatar, M. A.; Garlea, V. O.; Prozorov, R.; Zhu, Y.; Aronson, M. C.

2014-09-01

We present a study of the crystal structure and physical properties of single crystals of a new Fe-based ternary compound, Zr2-xFe4Si16-y(x = 0.81, y = 6.06). Zr1.19Fe4Si9.94 is a layered compound, where stoichiometric β-FeSi2-derived slabs are separated by Zr-Si planes with substantial numbers of vacancies. High resolution transmission electron microscopy (HRTEM) experiments show that these Zr-Si layers consist of 3.5 nm domains where the Zr and Si vacancies are ordered within a supercell sixteen times the volume of the stoichiometric cell. Within these domains, the occupancies of the Zr and Si sites obey symmetry rules that permit only certain compositions, none of which by themselves reproduce the average composition found in x-ray diffraction experiments. Magnetic susceptibility and magnetization measurements reveal a small but appreciable number of magnetic moments that remain freely fluctuating to 1.8 K, while neutron diffraction confirms the absence of bulk magnetic order with a moment of 0.2μB or larger down to 1.5 K. Electrical resistivity measurements find that Zr1.19Fe4Si9.94 is metallic, and the modest value of the Sommerfeld coefficient of the specific heat γ = C/T suggests that quasi-particle masses are not particularly strongly enhanced. The onset of superconductivity at Tc ≃ 6 K results in a partial resistive transition and a small Meissner signal, although a bulk-like transition is found in the specific heat. Sharp peaks in the ac susceptibility signal the interplay of the normal skin depth and the London penetration depth, typical of a system in which nano-sized superconducting grains are separated by a non-superconducting host. Ultra low field differential magnetic susceptibility measurements reveal the presence of a surprisingly large number of trace magnetic and superconducting phases, suggesting that the Zr-Fe-Si ternary system could be a potentially rich source of new bulk superconductors.

Alleviation of environmental risks associated with severely contaminated mine tailings using amendments: Modeling of trace element speciation, solubility, and plant accumulation.

PubMed

Pardo, Tania; Bes, Cleménce; Bernal, Maria Pilar; Clemente, Rafael

2016-11-01

Tailings are considered one of the most relevant sources of contamination associated with mining activities. Phytostabilization of mine spoils may need the application of the adequate combination of amendments to facilitate plant establishment and reduce their environmental impact. Two pot experiments were set up to assess the capability of 2 inorganic materials (calcium carbonate and a red mud derivate, ViroBind TM ), alone or in combination with organic amendments, for the stabilization of highly acidic trace element-contaminated mine tailings using Atriplex halimus. The effects of the treatments on tailings and porewater physico-chemical properties and trace-element accumulation by the plants, as well as the processes governing trace elements speciation and solubility in soil solution and their bioavailability were modeled. The application of the amendments increased tailings pH and decreased (>99%) trace elements solubility in porewater, but also changed the speciation of soluble Cd, Cu, and Pb. All the treatments made A. halimus growth in the tailings possible; organic amendments increased plant biomass and nutritional status, and reduced trace-element accumulation in the plants. Tailings amendments modified trace-element speciation in porewater (favoring the formation of chlorides and/or organo-metallic forms) and their solubility and plant uptake, which were found to be mainly governed by tailing/porewater pH, electrical conductivity, and organic carbon content, as well as soluble/available trace-element concentrations. Environ Toxicol Chem 2016;35:2874-2884. © 2016 SETAC. © 2016 SETAC.

The geographic distribution of trace elements in the environment: the REGARDS study.

PubMed

Rembert, Nicole; He, Ka; Judd, Suzanne E; McClure, Leslie A

2017-02-01

Research on trace elements and the effects of their ingestion on human health is often seen in scientific literature. However, little research has been done on the distribution of trace elements in the environment and their impact on health. This paper examines what characteristics among participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study are associated with levels of environmental exposure to arsenic, magnesium, mercury, and selenium. Demographic information from REGARDS participants was combined with trace element concentration data from the US Geochemical Survey (USGS). Each trace element was characterized as either low (magnesium and selenium) or high (arsenic and mercury) exposure. Associations between demographic characteristics and trace element concentrations were analyzed with unadjusted and adjusted logistic regression models. Individuals who reside in the Stroke Belt have lower odds of high exposure (4th quartile) to arsenic (OR 0.33, CI 0.31, 0.35) and increased exposure to mercury (OR 0.65, CI 0.62, 0.70) than those living outside of these areas, while the odds of low exposure to trace element concentrations were increased for magnesium (OR 5.48, CI 5.05, 5.95) and selenium (OR 2.37, CI 2.22, 2.54). We found an association between levels of trace elements in the environment and geographic region of residence, among other factors. Future studies are needed to further examine this association and determine whether or not these differences may be related to geographic variation in disease.

Level of minerals and trace elements in the urine of the participants of mountain ultra-marathon race.

PubMed

Jablan, Jasna; Inić, Suzana; Stosnach, Hagen; Hadžiabdić, Maja Ortner; Vujić, Lovorka; Domijan, Ana-Marija

2017-05-01

The aim of the present study was to explore impact of endurance exercise on urinary level of minerals and trace elements as well as on some oxidative stress and biochemical parameters. Urine samples were collected from participants (n=21) of mountain ultra-marathon race (53km; Medvednica, Zagreb, Croatia), before (baseline value), immediately after, 12h and 24h after the race. In urine samples level of minerals (Ca, P, K and Na) and trace elements (Se, Zn, Mn, Cu, Fe and Co) were assessed using the bench top Total reflection X-ray Fluorescence (TXRF) spectrometer. Oxidative stress was determined as level of malondialdehyde (MDA). Immediately after the race level of minerals, trace elements, MDA, creatinine, ketones, erythrocytes and specific gravity increased compared to their baseline value. In 24h follow-up trace elements involved in antioxidant defence, MDA and biochemical parameters returned to their baseline values, Cu and Co remained increased as after the race, Fe and K tended to return to baseline values while Ca, P and Na continued to increase. Mountain ultra-marathon resulted in alteration of physiologically important minerals and trace elements that for some minerals and trace elements persist, indicating their involvement in recovery processes. However, due to their loss in urine, level of minerals and trace elements in athletes participating in endurance exercise should be monitored. Copyright © 2017 Elsevier GmbH. All rights reserved.