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.

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.

Siderophile and chalcophile element abundances in oceanic basalts, Pb isotope evolution and growth of the earth's core

NASA Technical Reports Server (NTRS)

Newsom, H. E.; White, W. M.; Jochum, K. P.; Hofmann, A. W.

1986-01-01

The hypothesis that the mantle Pb isotope ratios reflect continued extraction of Pb into the earth's core over geologic time is evaluated by studying the depeletion of chalcophile and siderophile elements in the mantle. Oceanic basalt samples are analyzed in order to determine the Pb, Sr, and Nd isotropic compositions and the abundances of siderophile and chalcophile elements and incompatible lithophile elements. The data reveal that there is no systematic variation of siderophile or chalcophile element abundances relative to abundances of lithophile elements and the Pb/Ce ratio of the mantle is constant. It is suggested that the crust formation involves nonmagmatic and magmatic processes.

Magma genesis in the lesser Antilles island arc

NASA Astrophysics Data System (ADS)

Hawkesworth, C. J.; Powell, M.

1980-12-01

143Nd/ 144Nd, 87Sr/ 86Sr and REE results are reported on volcanic rocks from the islands of Dominica and St. Kitts in the Lesser Antilles. Particular attention is given to the lavas and xenoliths of the Foundland (basalt-andesite) and the Plat Pays (andesite-dacite) volcanic centres on Dominica. Combined major and trace element [ 2] and isotope results suggest that the bulk of the andesites and dacites on Dominica, and by analogy in the rest of the arc, are produced by fractional crystallisation of basaltic magma. The differences in the erupted products of the two volcanoes do not appear to be related to any significant differences in the source rocks of the magmas. Along the arc 87Sr/ 86Sr ratios range from 0.7037 on St. Kitts, to 0.7041-0.7047 on Dominica, and 0.7039-0.7058 on Grenada [ 5], and these are accompanied by a parallel increase in K, Sr, Ba and the light REE's. Moreover, compared with LIL-element-enriched and -depleted rocks from MOR and intraplate environments, the basic rocks from the Lesser Antilles are preferentially enriched in alkaline elements (K, Ba, Rb, Sr) relative to less mobile elements such as the rare earths. 143Nd/ 144Nd varies from 0.51308 on St. Kitts, to 0.51286 on Dominica, and 0.51264-0.51308 on Grenada [ 5], and all these samples have relatively high 87Sr/ 86Sr ratios compared with the main trend of Nd and Sr isotopes for most mantle-derived volcanic rocks. Alkaline elements and 87Sr appear to have been introduced from the subducted ocean crust, but the results on other, less mobile elements are more ambiguous — island arc tholeiites (as on St. Kitts) do not appear to contain significant amounts of REE's, Zr, Y, etc., from the subducted oceanic crust, but such a contribution may be present in more LIL-element-enriched calc-alkaline rock types.

Mg/Ca, Sr/Ca and Ca isotope ratios in benthonic foraminifers related to test structure, mineralogy and environmental controls

NASA Astrophysics Data System (ADS)

Gussone, Nikolaus; Filipsson, Helena L.; Kuhnert, Henning

2016-01-01

We analysed Mg/Ca, Sr/Ca and Ca isotope ratios of benthonic foraminifers from sediment core tops retrieved during several research cruises in the Atlantic Ocean, in order to improve the understanding of isotope fractionation and element partitioning resulting from biomineralisation processes and changes in ambient conditions. Species include foraminifers secreting tests composed of hyaline low magnesium calcite, porcelaneous high magnesium calcite as well as aragonite. Our results demonstrate systematic isotope fractionation and element partitioning patterns specific for these foraminiferal groups. Calcium isotope fractionation is similar in porcelaneous and hyaline calcite tests and both groups demonstrate the previously described anomaly with enrichment of heavy isotopes around 3-4 °C (Gussone and Filipsson, 2010). Calcium isotope ratios of the aragonitic species Hoeglundina elegans, on the other hand, are about 0.4‰ lighter compared to the calcitic species, which is in general agreement with stronger fractionation in inorganic aragonite compared to calcite. However, the low and strongly variable Sr content suggests additional processes during test formation, and we propose that transmembrane ion transport or a precursor phase to aragonite may be involved. Porcelaneous tests, composed of high Mg calcite, incorporate higher amounts of Sr compared to hyaline low Mg calcite, in agreement with inorganic calcite systematics, but also porcelaneous tests with reduced Mg/Ca show high Sr/Ca. While calcium isotopes, Sr/Ca and Mg/Ca in benthonic foraminifers primarily appear to fractionate and partition with a dominant inorganic control, δ44/40Ca temperature and growth rate dependencies of benthonic foraminifer tests favour a dominant contribution of light Ca by transmembrane transport relative to unfractionated seawater Ca to the calcifying fluid, thus controlling the formation of foraminiferal δ44/40Ca and Sr/Ca proxy signals.

A functional (E)-4-hydroxy-3-methylbut-2-enyl diphosphate reductase exhibits diurnal regulation of expression in Stevia rebaudiana (Bertoni).

PubMed

Kumar, Hitesh; Kumar, Sanjay

2013-09-15

The leaves of stevia [Stevia rebaudiana (Bertoni)] are a rich source of steviol glycosides that are used as non-calorific sweetener in many countries around the world. Steviol moiety of steviol glycosides is synthesized via plastidial 2C-methyl-D-erythritol 4-phosphate pathway, where (E)-4-hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR) is the key enzyme. HDR catalyzes the simultaneous conversion of (E)-4-hydroxy-3-methylbut-2-enyl diphosphate into five carbon isoprenoid units, isopentenyl diphosphate and dimethylallyl diphosphate. Stevia HDR (SrHDR) successfully rescued HDR lethal mutant strain MG1655 ara<>ispH upon genetic complementation, suggesting SrHDR to encode a functional protein. The gene exhibited diurnal variation in expression. To identify the possible regulatory elements, upstream region of the gene was cloned and putative cis-acting elements were detected by in silico analysis. Electrophoretic mobility shift assay, using a putative light responsive element GATA showed the binding of nuclear proteins (NP) isolated from leaves during light period of the day, but not with the NP from leaves during the dark period. Data suggested the involvement of GATA box in light mediated gene regulation of SrHDR in stevia. Copyright © 2013 Elsevier B.V. All rights reserved.

Microarray expression profiling identifies genes with altered expression in HDL-deficient mice

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

Callow, Matthew J.; Dudoit, Sandrine; Gong, Elaine L.

2000-05-05

Based on the assumption that severe alterations in the expression of genes known to be involved in HDL metabolism may affect the expression of other genes we screened an array of over 5000 mouse expressed sequence tags (ESTs) for altered gene expression in the livers of two lines of mice with dramatic decreases in HDL plasma concentrations. Labeled cDNA from livers of apolipoprotein AI (apo AI) knockout mice, Scavenger Receptor BI (SR-BI) transgenic mice and control mice were co-hybridized to microarrays. Two-sample t-statistics were used to identify genes with altered expression levels in the knockout or transgenic mice compared withmore » the control mice. In the SR-BI group we found 9 array elements representing at least 5 genes to be significantly altered on the basis of an adjusted p value of less than 0.05. In the apo AI knockout group 8 array elements representing 4 genes were altered compared with the control group (p < 0.05). Several of the genes identified in the SR-BI transgenic suggest altered sterol metabolism and oxidative processes. These studies illustrate the use of multiple-testing methods for the identification of genes with altered expression in replicated microarray experiments of apo AI knockout and SR-BI transgenic mice.« less

Subduction and melting processes inferred from U-Series, Sr Nd Pb isotope, and trace element data, Bicol and Bataan arcs, Philippines

NASA Astrophysics Data System (ADS)

DuFrane, S. Andrew; Asmerom, Yemane; Mukasa, Samuel B.; Morris, Julie D.; Dreyer, Brian M.

2006-07-01

We present U-series, Sr-Nd-Pb isotope, and trace element data from the two principal volcanic chains on Luzon Island, developed over oppositely dipping subduction zones, to explore melting and mass transfer processes beneath arcs. The Bataan (western) and Bicol (eastern) arcs are currently subducting terrigenous and pelagic sediments, respectively, which have different trace element and isotopic compositions. The range of ( 230Th/ 238U) disequilibria for both arcs is 0.85-1.15; only lavas from Mt. Mayon (Bicol arc) have 230Th activity excesses. Bataan lavas have higher 87Sr/ 86Sr and lower 143Nd/ 144Nd than Bicol lavas ( 87Sr/ 86Sr = 0.7042-0.7046, 143Nd/ 144Nd = 0.51281-0.51290 vs. 87Sr/ 86Sr = 0.70371-0.70391, 143Nd/ 144Nd = 0.51295-0.51301) and both arcs show steep linear arrays towards sediment values on 207Pb/ 204Pb vs. 206Pb/ 204Pb diagrams. Analysis of incompatible element and isotopic data allows identification of a sediment component that, at least in part, was transferred as a partial melt to the mantle wedge peridotite. Between 1% and 5% sediment melt addition can explain the isotopic and trace element variability in the rocks from both arcs despite the differences in sediment supply. We therefore propose that sediment transfer to the mantle wedge is likely mechanically or thermally limited. It follows that most sediments are either accreted, reside in the sub-arc lithosphere, or are recycled into the convecting mantle. However, whole-sale sediment recycling into the upper mantle is unlikely in light of the global mid-ocean ridge basalt data. Fluid involvement is more difficult to characterize, but overall the Bicol arc appears to have more fluid influence than the Bataan arc. Rock suites from each arc can be related by a dynamic melting process that allows for 230Th ingrowth, either by dynamic or continuous flux melting, provided the initial ( 230Th/ 232Th) of the source is ˜0.6-0.7. The implication of either model is that inclined arrays on the U-Th equiline diagram may not have chronologic significance. Modeling also suggests that U-series disequilibria are influenced by the tectonic convergence rate, which dictates mantle matrix flow. Thus with slower matrix flow there is a greater degree of 230Th ingrowth. While other factors such as prior mantle depletion and addition of a subducted component may explain some aspects of U-series data, an overall global correlation between tectonic convergence rate and the extent of U-Th disequilibria may originate from melting processes.

Substantial enhancement in intrinsic coercivity on M-type strontium hexaferrite through the increase in magneto-crystalline anisotropy by co-doping of group-V and alkali elements

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

Ahn, Kyunghan, E-mail: kyunghan.ahn@samsung.com; Ryu, Byungki; Korolev, Dmitry

2013-12-09

The effect of d{sup 1} impurity doping in Sr-hexaferrite (SrM) on the magnetic anisotropy is investigated. First-principles calculations revealed that group-V elements (V, Nb) are stabilized with co-doping of alkali elements. Na{sup 1+}/K{sup 1+} doping at Sr{sup 2+}-site is found to be critical to form the d{sup 1} impurities at Fe-site. Experimentally, Na–V doped SrM shows the intrinsic coercivity of ∼5.4 kOe, which is ∼300% enhancement compared to undoped SrM and comparable value to La–Co co-doped SrM. Finally, the spin-orbit coupling from non-vanishing angular momentum of d{sup 1} impurity in SrM should be a main factor for such a substantialmore » improvement of intrinsic coercivity.« less

Major and trace element, and Sr isotope compositions of clinopyroxene phenocrysts in mafic dykes on Jiaodong Peninsula, southeastern North China Craton: Insights into magma mixing and source metasomatism

NASA Astrophysics Data System (ADS)

Liang, Yayun; Deng, Jun; Liu, Xuefei; Wang, Qingfei; Qin, Cheng; Li, Yan; Yang, Yi; Zhou, Mian; Jiang, Jieyan

2018-03-01

Early Cretaceous mafic dyke swarms are widely developed on Jiaodong Peninsula in the southeastern part of the North China Craton (NCC), but their petrogenesis remains enigmatic. We have examined the in-situ major element, trace element and Sr isotope compositions of the clinopyroxene phenocrysts in these dykes in order to evaluate the extent of magma mixing and source metasomatism. Depending on the type of mineral zoning, the clinopyroxene phenocrysts in our samples can be classified into two groups: Group I (reverse zoning) and Group II (no zoning). Based on core compositions, the Group I phenocrysts with obvious reverse zoning can be divided into two subgroups: Groups IA and IB. The cores of Group IA clinopyroxenes have low values of Mg#, low Al2O3 contents, high Na2O contents, and high 87Sr/86Sr ratios, and they were probably derived from newly accreted lower crust that formed through the underplating of basaltic magma. In contrast, the cores of Group IB clinopyroxenes have lower Mg# values and lower contents of Al2O3, ΣREE (total rare earth elements), and incompatible elements, but they have similar 87Sr/86Sr ratios; these cores crystallised from crust-derived andesitic-dacitic magma. Group IA and IB clinopyroxene phenocryst rims (Group I rims) all have similar compositions with higher values of Mg# and higher Al2O3, Cr and Ni contents than the cores. The rims have high 87Sr/86Sr ratios, are enriched in LREEs (light rare earth elements) and LILEs (large ion lithophile elements), and are depleted in HFSEs (high field strength elements); these characteristics indicate that all the high-Mg rims were derived from a similar magma, possibly a relatively primitive magma derived from lithospheric mantle. We suggest, therefore, that the reversely-zoned clinopyroxene phenocrysts (Group I) in the Jiaodong mafic dykes provide evidence of magma mixing between a magma derived from lithospheric mantle and crust-derived andesitic-dacitic melt alongside with the newly accreted lower crust. The Group II clinopyroxene phenocrysts, which lack zoning, display major and trace element compositions and 87Sr/86Sr ratios that are similar to those of the Group I rims, which indicates that all the high-Mg clinopyroxenes were derived from a common source in the lithospheric mantle. These high-Mg clinopyroxenes exhibit high 87Sr/86Sr ratios, high Sr contents and remarkable depletions in HFSEs, reflecting metasomatism of the mantle source by aqueous fluids derived by dehydration of the subducting slab and its marine sediments. The metasomatism of the source reveals that the lithospheric mantle beneath Jiaodong Peninsula was metasomatised by fluids from the subducting Paleo-Pacific slab. Progressive thinning of the lithosphere mantle under the NCC was induced by continuous thermo-mechanical erosion, promoting the partial melting of lithospheric mantle and generating the mafic dykes at Jiaodong. Table A2 Analytical results for the trace element standards used during LA-ICP-MS analyses of clinopyroxene phenocrysts. Table A3 Analytical results for the Sr isotope standards used during MC-ICP-MS analyses of clinopyroxene phenocrysts. Table A4 Major element contents (wt%) of clinopyroxene phenocrysts from the mafic dykes on Jiaodong Peninsula. Table A5 Representative Sr isotopic compositions of clinopyroxene phenocrysts from the mafic dykes on Jiaodong Peninsula. Table A6 Geochemistry of the mafic dykes on Jiaodong Peninsula. Table A7 Partition coefficients (KD) and end-member components used for REE modeling.

A calmodulin-binding/CGCG box DNA-binding protein family involved in multiple signaling pathways in plants

NASA Technical Reports Server (NTRS)

Yang, Tianbao; Poovaiah, B. W.

2002-01-01

We reported earlier that the tobacco early ethylene-responsive gene NtER1 encodes a calmodulin-binding protein (Yang, T., and Poovaiah, B. W. (2000) J. Biol. Chem. 275, 38467-38473). Here we demonstrate that there is one NtER1 homolog as well as five related genes in Arabidopsis. These six genes are rapidly and differentially induced by environmental signals such as temperature extremes, UVB, salt, and wounding; hormones such as ethylene and abscisic acid; and signal molecules such as methyl jasmonate, H(2)O(2), and salicylic acid. Hence, they were designated as AtSR1-6 (Arabidopsis thaliana signal-responsive genes). Ca(2+)/calmodulin binds to all AtSRs, and their calmodulin-binding regions are located on a conserved basic amphiphilic alpha-helical motif in the C terminus. AtSR1 targets the nucleus and specifically recognizes a novel 6-bp CGCG box (A/C/G)CGCG(G/T/C). The multiple CGCG cis-elements are found in promoters of genes such as those involved in ethylene signaling, abscisic acid signaling, and light signal perception. The DNA-binding domain in AtSR1 is located on the N-terminal 146 bp where all AtSR1-related proteins share high similarity but have no similarity to other known DNA-binding proteins. The calmodulin-binding nuclear proteins isolated from wounded leaves exhibit specific CGCG box DNA binding activities. These results suggest that the AtSR gene family encodes a family of calmodulin-binding/DNA-binding proteins involved in multiple signal transduction pathways in plants.

Strontium Isotopic Composition of Paleozoic Carbonate Rocks in the Nevada Test Site Vicinity, Clark, Lincoln, and Nye Counties, Nevada and Inyo County, California.

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

James B. Paces; Zell E. Peterman; Kiyoto Futa

2007-08-07

Ground water moving through permeable Paleozoic carbonate rocks represents the most likely pathway for migration of radioactive contaminants from nuclear weapons testing at the Nevada Test Site, Nye County, Nevada. The strontium isotopic composition (87Sr/86Sr) of ground water offers a useful means of testing hydrochemical models of regional flow involving advection and reaction. However, reaction models require knowledge of 87Sr/86Sr data for carbonate rock in the Nevada Test Site vicinity, which is scarce. To fill this data gap, samples of core or cuttings were selected from 22 boreholes at depth intervals from which water samples had been obtained previously aroundmore » the Nevada Test Site at Yucca Flat, Frenchman Flat, Rainier Mesa, and Mercury Valley. Dilute acid leachates of these samples were analyzed for a suite of major- and trace-element concentrations (MgO, CaO, SiO2, Al2O3, MnO, Rb, Sr, Th, and U) as well as for 87Sr/86Sr. Also presented are unpublished analyses of 114 Paleozoic carbonate samples from outcrops, road cuts, or underground sites in the Funeral Mountains, Bare Mountain, Striped Hills, Specter Range, Spring Mountains, and ranges east of the Nevada Test Site measured in the early 1990's. These data originally were collected to evaluate the potential for economic mineral deposition at the potential high-level radioactive waste repository site at Yucca Mountain and adjacent areas (Peterman and others, 1994). Samples were analyzed for a suite of trace elements (Rb, Sr, Zr, Ba, La, and Ce) in bulk-rock powders, and 87Sr/86Sr in partial digestions of carbonate rock using dilute acid or total digestions of silicate-rich rocks. Pre-Tertiary core samples from two boreholes in the central or western part of the Nevada Test Site also were analyzed. Data are presented in tables and summarized in graphs; however, no attempt is made to interpret results with respect to ground-water flow paths in this report. Present-day 87Sr/86Sr values are compared to values for Paleozoic seawater present at the time of deposition. Many of the samples have 87Sr/86Sr compositions that remain relatively unmodified from expected seawater values. However, rocks underlying the northern Nevada Test Site as well as rocks exposed at Bare Mountain commonly have elevated 87Sr/86Sr values derived from post-depositional addition of radiogenic Sr most likely from fluids circulating through rubidium-rich Paleozoic strata or Precambrian basement rocks.« less

Strontium Isotopic Composition of Paleozoic Carbonate Rocks in the Nevada Test Site Vicinity, Clark, Lincoln, and Nye Counties, Nevada, and Inyo County, California

USGS Publications Warehouse

Paces, James B.; Peterman, Zell E.; Futo, Kiyoto; Oliver, Thomas A.; Marshall, Brian D.

2007-01-01

Ground water moving through permeable Paleozoic carbonate rocks represents the most likely pathway for migration of radioactive contaminants from nuclear weapons testing at the Nevada Test Site, Nye County, Nevada. The strontium isotopic composition (87Sr/86Sr) of ground water offers a useful means of testing hydrochemical models of regional flow involving advection and reaction. However, reaction models require knowledge of 87Sr/86Sr data for carbonate rock in the Nevada Test Site vicinity, which is scarce. To fill this data gap, samples of core or cuttings were selected from 22 boreholes at depth intervals from which water samples had been obtained previously around the Nevada Test Site at Yucca Flat, Frenchman Flat, Rainier Mesa, and Mercury Valley. Dilute acid leachates of these samples were analyzed for a suite of major- and trace-element concentrations (MgO, CaO, SiO2, Al2O3, MnO, Rb, Sr, Th, and U) as well as for 87Sr/86Sr. Also presented are unpublished analyses of 114 Paleozoic carbonate samples from outcrops, road cuts, or underground sites in the Funeral Mountains, Bare Mountain, Striped Hills, Specter Range, Spring Mountains, and ranges east of the Nevada Test Site measured in the early 1990's. These data originally were collected to evaluate the potential for economic mineral deposition at the potential high-level radioactive waste repository site at Yucca Mountain and adjacent areas (Peterman and others, 1994). Samples were analyzed for a suite of trace elements (Rb, Sr, Zr, Ba, La, and Ce) in bulk-rock powders, and 87Sr/86Sr in partial digestions of carbonate rock using dilute acid or total digestions of silicate-rich rocks. Pre-Tertiary core samples from two boreholes in the central or western part of the Nevada Test Site also were analyzed. Data are presented in tables and summarized in graphs; however, no attempt is made to interpret results with respect to ground-water flow paths in this report. Present-day 87Sr/86Sr values are compared to values for Paleozoic seawater present at the time of deposition. Many of the samples have 87Sr/86Sr compositions that remain relatively unmodified from expected seawater values. However, rocks underlying the northern Nevada Test Site as well as rocks exposed at Bare Mountain commonly have elevated 87Sr/86Sr values derived from post-depositional addition of radiogenic Sr most likely from fluids circulating through rubidium-rich Paleozoic strata or Precambrian basement rocks.

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.

Source area and seasonal variation of dissolved Sr isotope composition in rivers of the Amazon basin

NASA Astrophysics Data System (ADS)

Santos, Roberto V.; Sondag, Francis; Cochonneau, Gerard; Lagane, Christelle; Brunet, Pierre; Hattingh, Karina; Chaves, Jeane G. S.

2014-05-01

We present dissolved Sr isotope data collected over 8 years from three main river systems from the Amazon Basin: Beni-Madeira, Solimões, Amazon, and Negro. The data show large 87Sr/86Sr ratio variations that were correlated with the water discharge and geology of the source areas of the suspended sediments. The Beni-Madeira system displays a high average 87Sr/86Sr ratio and large 87Sr/86Sr fluctuations during the hydrological cycle. This large average value and fluctuations were related to the presence of Precambrian rocks and Ordovician sediments in the source area of the suspended sediment of the river. In contrast, the Solimões system displays a narrow range of Sr isotope ratio variations and an average value close to 0.709. This river drains mostly Phanerozoic rocks of northern Peru and Ecuador that are characterized by low Sr isotope ratios. Despite draining areas underlain by Precambrian rocks and having high 87Sr/86Sr ratios, such rivers as the Negro and Tapajós play a minor role in the total Sr budget of the Amazon Basin. The isotopic fluctuations in the Beni-Madeira River were observed to propagate downstream at least as far as Óbidos, in the Amazon River. This signal is characterized by an inverse relationship between the concentration of elemental Sr and its isotopic ratios. During the raining season there is an increase in Sr isotopic ratio accompanied by a decrease in elemental Sr concentration. During the dry season, the Sr isotopic ration decreases and the elemental Sr concentration increases.

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.

The Use of Isotope Dilution Alpha Spectrometry and Liquid Scintillation Counting to Determine Radionuclides in Environmental Samples (abstract)

NASA Astrophysics Data System (ADS)

Bylyku, Elida

2009-04-01

In Albania in recent years it has been of increasing interest to determine various pollutants in the environment and their possible effects on human health. The radiochemical procedure used to identify Pu, Am, U, Th, and Sr radioisotopes in soil, sediment, water, coal, and milk samples is described. The analysis is carried out in the presence of respective tracer solutions and combines the procedure for Pu analysis based on anion exchange, the selective method for Sr isolation based on extraction chromatography using Sr-Spec resin, and the application of the TRU-Spec column for separation of Am fraction. An acid digestion method has been applied for the decomposition of samples. The radiochemical procedure involves the separation of Pu from Th, Am, and Sr by anion exchange, followed by the preconcentration of Am and Sr by coprecipitation with calcium oxalate. Am is separated from Sr by extraction chromatography. Uranium is separated from the bulk elements by liquid-liquid extraction using UTEVA® resin. Thin sources for alpha spectrometric measurements are prepared by microprecipitation with NdF3. Two International Atomic Energy Agency reference materials were analyzed in parallel with the samples.

Origin discrimination of defatted pork via trace elements profiling, stable isotope ratios analysis, and multivariate statistical techniques.

PubMed

Park, Yu Min; Lee, Cheong Mi; Hong, Joon Ho; Jamila, Nargis; Khan, Naeem; Jung, Jong-Hyun; Jung, Young-Chul; Kim, Kyong Su

2018-09-01

This study verified the origin of 346 defatted Korean and non-Korean pork samples via trace elements profiling, and C and N stable isotope ratios analysis. The analyzed elements were 6 Li, 7 Li, 10 B, 11 B, 51 V , 50 Cr, 52 Cr, 53 Cr, 55 Mn, 58 Ni, 60 Ni, 59 Co, 63 Cu, 65 Cu, 64 Zn, 66 Zn, 69 Ga, 71 Ga, 75 As, 82 Se, 84 Sr, 86 Sr, 87 Sr, 88 Sr, 85 Rb, 94 Mo, 95 Mo, 97 Mo, 107 Ag, 109 Ag, 110 Cd, 111 Cd, 113 Cd, 112 Cd, 114 Cd, 116 Cd, 133 Cs, 206 Pb, 207 Pb, and 208 Pb. Content (mg/kg) of 51 V (0.012), 50 Cr (0.882), 75 As (0.017), 85 Rb (57.7), and 87 Sr (46.3) were high in Korean pork samples whereas 6 Li, 7 Li, 59 Co, 55 Mn, 58 Ni, 84 Sr, 86 Sr, 88 Sr, 111 Cd, and 133 Cs were found higher in non-Korean samples. The results of discriminant analysis showed that the trace elements content and stable isotope ratios were significant for the discrimination of geographical origins with a perfect discrimination rate of 100%. Copyright © 2018 Elsevier Ltd. All rights reserved.

Potential of Sr isotopic analysis in ceramic provenance studies: Characterisation of Chinese stonewares

NASA Astrophysics Data System (ADS)

Li, Bao-Ping; Zhao, Jian-Xin; Greig, Alan; Collerson, Kenneth D.; Zhuo, Zhen-Xi; Feng, Yue-Xin

2005-11-01

We compare the trace element and Sr isotopic compositions of stoneware bodies made in Yaozhou and Jizhou to characterise these Chinese archaeological ceramics and examine the potential of Sr isotopes in provenance studies. Element concentrations determined by ICP-MS achieve distinct characterisation for Jizhou samples due to their restricted variation, yet had limited success with Yaozhou wares because of their large variability. In contrast, 87Sr/86Sr ratios in Yaozhou samples have a very small variation and are all significantly lower than those of Jizhou samples, which show a large variation and cannot be well characterised with Sr isotopes. Geochemical interpretation reveals that 87Sr/86Sr ratios will have greater potential to characterise ceramics made of low Rb/Sr materials such as kaolin clay, yet will show larger variations in ceramics made of high Rb/Sr materials such as porcelain stone.

Sr and Nd isotopic and trace element compositions of Quaternary volcanic centers of the Southern Andes

USGS Publications Warehouse

Futa, K.; Stern, C.R.

1988-01-01

Isotopic compositions of samples from six Quaternary volcanoes located in the northern and southern extremities of the Southern Volcanic Zone (SVZ, 33-46??S) of the Andes and from four centers in the Austral Volcanic Zone (AVZ, 49-54??S) range for 87Sr 86Sr from 0.70280 to 0.70591 and for 143Nd 144Nd from 0.51314 to 0.51255. The ranges are significantly greater than previously reported from the southern Andes but are different from the isotopic compositions of volcanoes in the central and northern Andes. Basalts and basaltic andesites from three centers just north of the Chile Rise-Trench triple junction have 87Sr 86Sr, 143Nd 144Nd, La Yb, Ba La, and Hf Lu that lie within the relatively restricted ranges of the basic magmas erupted from the volcanic centers as far north as 35??S in the SVZ of the Andes. The trace element and Sr and Nd isotopic characteristics of these magmas may be explained by source region contamination of subarc asthenosphere, with contaminants derived from subducted pelagic sediments and seawater-altered basalts by dehydration of subducted oceanic lithosphere. In the northern extremity of the SVZ between 33?? and 34??S, basaltic andesites and andesites have higher 87Sr 86Sr, Rb Cs, and Hf Lu, and lower 143Nd 144Nd than basalts and basaltic andesites erupted farther south in the SVZ, which suggests involvement of components derived from the continental crust. In the AVZ, the most primitive sample, high-Mg andesite from the southernmost volcanic center in the Andes (54??S) has Sr and Nd isotopic compositions and K Rb and Ba La similar to MORB. The high La Yb of this sample suggests formation by small degrees of partial melting of subducted MORB with garnet as a residue. Samples from centers farther north in the AVZ show a regionally regular northward increase in SiO2, K2O, Rb, Ba, Ba La, and 87Sr 86Sr and decrease in MgO, Sr, K Rb, Rb Cs, and 143Nd 144Nd, suggesting increasingly greater degrees of fractional crystallization and associated intra-crustal contamination. ?? 1988.

Isotopic decoupling during porous melt flow: A case-study in the Lherz peridotite

NASA Astrophysics Data System (ADS)

Le Roux, V.; Bodinier, J.-L.; Alard, O.; O'Reilly, S. Y.; Griffin, W. L.

2009-03-01

Most peridotite massifs and mantle xenoliths show a wide range of isotopic variations, often involving significant decoupling between Hf, Nd and Sr isotopes. These variations are generally ascribed either to mingling of individual components of contrasted isotopic compositions or to time integration of parent-element enrichment by percolating melts/fluids, superimposed onto previous depletion event(s). However, strong isotopic decoupling may also arise during porous flow as a result of daughter-elements fractionation during solid-liquid interaction. Although porous flow is recognized as an important process in mantle rocks, its effects on mantle isotopic variability have been barely investigated so far. The peridotites of the Lherz massif (French Pyrenees) display a frozen melt percolation front separating highly refractory harzburgites from refertilized lherzolites. Isotopic signatures observed at the melt percolation front show a strong decoupling of Hf from Nd and Sr isotopes that cannot be accounted for by simple mixing involving the harzburgite protolith and the percolating melt. Using one dimensional percolation-diffusion and percolation-reaction modeling, we show that these signatures represent transient isotopic compositions generated by porous flow. These signatures are governed by a few critical parameters such as daughter element concentrations in melt and peridotite, element diffusivity, and efficiency of isotopic homogenization rather than by the chromatographic effect of melt transport and the refertilization reaction. Subtle variations in these parameters may generate significant inter-isotopic decoupling and wide isotopic variations in mantle rocks.

A Rb-Sr and Sm-Nd Isotope Geochronology and Trace Element Study of Lunar Meteorite LaPaz Icefield 02205

NASA Technical Reports Server (NTRS)

Rankenburg, K.; Brandon, A. D.; Norman, M. D.

2007-01-01

Rubidium-strontium and samarium-neodymium isotopes of lunar meteorite LaPaz Icefield (LAP) 02205 are consistent with derivation of the parent magma from a source region similar to that which produced the Apollo 12 low-Ti olivine basalts followed by mixing of the magma with small amounts (1 to 2 wt%) of trace element-enriched material similar to lunar KREEP-rich sample SaU 169. The crystallization age of LAP 02205 is most precisely dated by an internal Rb-Sr isochron of 2991+/-14 Ma, with an initial Sr-87/Sr-88 at the time of crystallization of 0.699836+/-0.000010. Leachable REE-rich phosphate phases of LAP 02205 do not plot on a Sm-Nd mineral isochron, indicating contamination or open system behavior of the phosphates. Excluding anomalous phases from the calculation of a Sm-Nd isochron yields a crystallization age of 2992+/-85 (initial Epsilon Nd-143 = +2.9+/-0.8) that is within error of the Rb-Sr age, and in agreement with other independent age determinations for LAP 02205 from Ar-Ar and U-Pb methods. The calculated Sm-147/Nd-144 source ratios for LAP 02205, various Apollo 12 and 15 basalts, and samples with strong affinities to KREEP (SaU 169, NWA 773, 15386) are uncorrelated with their crystallization ages. This finding does not support the involvement of a common KREEP component as a heat source for lunar melting events that occurred after crystallization of the lunar magma ocean.

Splicing factor SR34b mutation reduces cadmium tolerance in Arabidopsis by regulating iron-regulated transporter 1 gene

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

Zhang, Wentao; Du, Bojing; Liu, Di

Highlights: • Arabidopsis splicing factor SR34b gene is cadmium-inducible. • SR34b T-DNA insertion mutant is sensitive to cadmium due to high cadmium uptake. • SR34b is a regulator of cadmium transporter IRT1 at the posttranscription level. • These results highlight the roles of splicing factors in cadmium tolerance of plant. - Abstract: Serine/arginine-rich (SR) proteins are important splicing factors. However, the biological functions of plant SR proteins remain unclear especially in abiotic stresses. Cadmium (Cd) is a non-essential element that negatively affects plant growth and development. In this study, we provided clear evidence for SR gene involved in Cd tolerancemore » in planta. Systemic expression analysis of 17 Arabidopsis SR genes revealed that SR34b is the only SR gene upregulated by Cd, suggesting its potential roles in Arabidopsis Cd tolerance. Consistent with this, a SR34b T-DNA insertion mutant (sr34b) was moderately sensitive to Cd, which had higher Cd{sup 2+} uptake rate and accumulated Cd in greater amounts than wild-type. This was due to the altered expression of iron-regulated transporter 1 (IRT1) gene in sr34b mutant. Under normal growth conditions, IRT1 mRNAs highly accumulated in sr34b mutant, which was a result of increased stability of IRT1 mRNA. Under Cd stress, however, sr34b mutant plants had a splicing defect in IRT1 gene, thus reducing the IRT1 mRNA accumulation. Despite of this, sr34b mutant plants still constitutively expressed IRT1 proteins under Cd stress, thereby resulting in Cd stress-sensitive phenotype. We therefore propose the essential roles of SR34b in posttranscriptional regulation of IRT1 expression and identify it as a regulator of Arabidopsis Cd tolerance.« less

U-Pb zircon, geochemical and Sr-Nd-Hf-O isotopic constraints on age and origin of the ore-bearing intrusions from the Nurkazgan porphyry Cu-Au deposit in Kazakhstan

NASA Astrophysics Data System (ADS)

Shen, Ping; Pan, Hongdi; Seitmuratova, Eleonora; Jakupova, Sholpan

2016-02-01

Nurkazgan, located in northeastern Kazakhstan, is a super-large porphyry Cu-Au deposit with 3.9 Mt metal copper and 229 tonnage gold. We report in situ zircon U-Pb age and Hf-O isotope data, whole rock geochemical and Sr-Nd isotopic data for the ore-bearing intrusions from the Nurkazgan deposit. The ore-bearing intrusions include the granodiorite porphyry, quartz diorite porphyry, quartz diorite, and diorite. Secondary ion mass spectrometry (SIMS) zircon U-Pb dating indicates that the granodiorite porphyry and quartz diorite porphyry emplaced at 440 ± 3 Ma and 437 ± 3 Ma, respectively. All host rocks have low initial 87Sr/86Sr ratios (0.70338-0.70439), high whole-rock εNd(t) values (+5.9 to +6.3) and very high zircon εHf(t) values (+13.4 to +16.5), young whole-rock Nd and zircon Hf model ages, and consistent and slightly high zircon O values (+5.7 to +6.7), indicating that the ore-bearing magmas derived from the mantle without old continental crust involvement and without marked sediment contamination during magma emplacement. The granodiorite porphyry and quartz diorite porphyry are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) and depleted in high-field strength elements (HFSE), Eu, Ba, Nb, Sr, P and Ti. The diorite and quartz diorite have also LILE and LREE enrichment and HFSE, Nb and Ti depletion, but have not negative Eu, Ba, Sr, and P anomalies. These features suggest that the parental magma of the granodiorite porphyry and quartz diorite porphyry originated from melting of a lithospheric mantle and experienced fractional crystallization, whereas the diorite and quartz diorite has a relatively deeper lithospheric mantle source region and has not experienced strong fractional crystallization. Based on these, together with the coeval ophiolites in the area, we propose that a subduction of the Balkhash-Junggar oceanic plate took place during the Early Silurian and the ore-bearing intrusions and associated Nurkazgan porphyry Cu-Au deposit occurred in an intra-oceanic arc setting.

Sr-Nd-Pb isotopic constraints on the nature of the mantle sources involved in the genesis of the high-Ti tholeiites from northern Paraná Continental Flood Basalts (Brazil)

NASA Astrophysics Data System (ADS)

Rocha-Júnior, Eduardo R. V.; Marques, Leila S.; Babinski, Marly; Nardy, Antônio J. R.; Figueiredo, Ana M. G.; Machado, Fábio B.

2013-10-01

There has been little research on geochemistry and isotopic compositions in tholeiites of the Northern region from the Paraná Continental Flood Basalts (PCFB), one of the largest continental provinces of the world. In order to examine the mantle sources involved in the high-Ti (Pitanga and Paranapanema) basalt genesis, we studied Sr, Nd, and Pb isotopic systematics, and major, minor and incompatible trace element abundances. The REE patterns of the investigated samples (Pitanga and Paranapanema magma type) are similar (parallel to) to those of Island Arc Basalts' REE patterns. The high-Ti basalts investigated in this study have initial (133 Ma) 87Sr/86Sr ratios of 0.70538-0.70642, 143Nd/144Nd of 0.51233-0.51218, 206Pb/204Pb of 17.74-18.25, 207Pb/204Pb of 15.51-15.57, and 208Pb/204Pb of 38.18-38.45. These isotopic compositions do not display any correlation with Nb/Th, Nb/La or P2O5/K2O ratios, which also reflect that these rocks were not significantly affected by low-pressure crustal contamination. The incompatible trace element ratios and Sr-Nd-Pb isotopic compositions of the PCFB tholeiites are different to those found in Tristan da Cunha ocean island rocks, showing that this plume did not play a substantial role in the PCFB genesis. This interpretation is corroborated by previously published osmium isotopic data (initial γOs values range from +1.0 to +2.0 for high-Ti basalts), which also preclude basalt generation by melting of ancient subcontinental lithospheric mantle. The geochemical composition of the northern PCFB may be explained through the involvement of fluids and/or small volume melts related to metasomatic processes. In this context, we propose that the source of these magmas is a mixture of sublithospheric peridotite veined and/or interlayered with mafic components (e.g., pyroxenites or eclogites). The sublithospheric mantle (dominating the osmium isotopic compositions) was very probably enriched by fluids and/or magmas related to the Neoproterozoic subduction processes. This sublithospheric mantle region may have been frozen and coupled to the base of the Parana basin lithospheric plate above which the Paleozoic subsidence and subsequent Early Cretaceous magmatism occurred.

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.

High-Precision In Situ 87Sr/86Sr Analyses through Microsampling on Solid Samples: Applications to Earth and Life Sciences

PubMed Central

Di Salvo, Sara; Casalini, Martina; Marchionni, Sara; Adani, Teresa; Ulivi, Maurizio; Tommasini, Simone; Avanzinelli, Riccardo; Mazza, Paul P. A.; Francalanci, Lorella

2018-01-01

An analytical protocol for high-precision, in situ microscale isotopic investigations is presented here, which combines the use of a high-performing mechanical microsampling device and high-precision TIMS measurements on micro-Sr samples, allowing for excellent results both in accuracy and precision. The present paper is a detailed methodological description of the whole analytical procedure from sampling to elemental purification and Sr-isotope measurements. The method offers the potential to attain isotope data at the microscale on a wide range of solid materials with the use of minimally invasive sampling. In addition, we present three significant case studies for geological and life sciences, as examples of the various applications of microscale 87Sr/86Sr isotope ratios, concerning (i) the pre-eruptive mechanisms triggering recent eruptions at Nisyros volcano (Greece), (ii) the dynamics involved with the initial magma ascent during Eyjafjallajökull volcano's (Iceland) 2010 eruption, which are usually related to the precursory signals of the eruption, and (iii) the environmental context of a MIS 3 cave bear, Ursus spelaeus. The studied cases show the robustness of the methods, which can be also be applied in other areas, such as cultural heritage, archaeology, petrology, and forensic sciences. PMID:29850369

Nature and Significance of the High-Sr Aleutian Lavas

NASA Astrophysics Data System (ADS)

Yogodzinski, G. M.; Arndt, S.; Turka, J. R.; Kelemen, P. B.; Vervoort, J. D.; Portnyagin, M.; Hoernle, K.

2011-12-01

Results of the Western Aleutian Volcano Expedition and German-Russian KALMAR cruises include the discovery of seafloor volcanism at the Ingenstrem Depression and at unnamed seamounts 300 km west of Buldir, the westernmost emergent volcano in the Aleutian arc. These discoveries indicate that the surface expression of active Aleutian volcanism goes below sea level just west of Buldir, but is otherwise continuous along the full length of the arc. Many lavas dredged from western Aleutian seamounts are basalts, geochemically similar to basalts from elsewhere in Aleutians and other arcs (La/Yb 4-8, Sr/Y<30, 87Sr/86Sr=0.7031-0.7033). Western Aleutian dredge samples also include high-Sr lavas (>700 ppm Sr), which are mostly plagioclase-hornblende andesites and dacites with low Y and middle-heavy rare-earth elements, fractionated trace element patterns (Sr/Y=50-200, La/Yb=9-25) and MORB-like isotopes (87Sr/86Sr < 0.7028). The endmember Sr-rich lavas are magnesian rhyodacites (SiO2~68%, Mg# >0.65) with 1250-1700 ppm Sr, 4-7 ppm Y, low abundances of all rare-earth elements (La<7 ppm, Yb<0.4 ppm) and 87Sr/86Sr < 0.70266. The high silica and primitive (high Mg#) character of the high-Sr lavas, combined with their strongly fractionated trace element patterns and MORB-like isotopes are consistent with a source predominantly of subducted basalt and a melt residue that contained garnet. The high-Sr lavas have some characteristics of MORB fluids (low Ce/Pb and unradiogenic Pb), and their highly calc-alkaline nature implies high pre-eruptive water contents[1], but low 87Sr/86Sr indicates that their source was in MORB, not seawater-altered MORB. The high-Sr endmember is clearly present in andesites from some emergent volcanoes in the western Aleutians, and mixing arrays indicate that it may be present in all Aleutian lavas (e.g., 87Sr/86Sr vs. La/Yb or Sr/Y); however, radiogenic Pb and Sr from subducted sediment renders the high-Sr endmember isotopically invisible in most central and eastern Aleutian lavas. The geochemistry of small monogenetic sea-floor volcanoes--especially those in the back-arc--may be the best opportunity to identify the high-Sr endmember in central and eastern Aleutian locations. The existence of primitive, high-silica lavas in the western Aleutians, where the subducting plate is probably unusually hot, may also provide key observations toward an improved understanding of high-Mg# andesites and dacites from other hot-slab locations, especially in the Cascades and Central Mexico. [1] Zimmer et al., 2010, J. Petrology, v. 51, p. 2411

Assessing elemental ratios as a paleotemperature proxy in shells of patelloid limpets

NASA Astrophysics Data System (ADS)

Graniero, L. E.; Surge, D. M.; Gillikin, D. P.

2016-02-01

Archaeological shell and fish middens are rich sources of paleoenvironmental proxy data. Patelloid limpet shells are common constituents in archaeological middens found along European, African, and South American coastlines. Paleotemperature reconstructions using oxygen isotope ratios of limpet shells depend on the ability to constrain the oxygen isotope ratio of seawater; therefore, alternative proxies are necessary for coastal localities where this is not possible. The study evaluates whether Mg/Ca, Sr/Ca, Li/Ca, Li/Mg, and Sr/Li ratios are reliable proxies of SST in shells of the patelloid limpets, P. vulgata and N. deaurata. We compare Mg/Ca, Sr/Ca, Li/Ca, Li/Mg, and Sr/Li ratios to the seasonal variations in contemporaneous δ18Oshell records which primarily record seasonal changes in SST. Elemental ratios (Mg/Ca, Sr/Ca, Li/Ca, Sr/Li, Li/Mg) show no significant correlations with reconstructed SST in P. vulgata and N. deaurata shells. Shell δ13C values show no significant ontogenetic trends, suggesting that these limpets show little change in metabolic carbon incorporation into the shell with increasing ontogenetic age. Although growth rate exhibits a logarithmic decrease with age based on calculated linear extension rates, growth rate does not correlate with elemental profiles in these limpets. Overall, elemental ratios (are not reliable recorders of paleotemperature in patelloid limpets. Further research is necessary to establish the controls on elemental ratio concentrations in limpet shells.

Electronic structure of α-SrB4O7: experiment and theory

NASA Astrophysics Data System (ADS)

Atuchin, V. V.; Kesler, V. G.; Zaitsev, A. I.; Molokeev, M. S.; Aleksandrovsky, A. S.; Kuzubov, A. A.; Ignatova, N. Y.

2013-02-01

The investigation of valence band structure and electronic parameters of constituent element core levels of α-SrB4O7 has been carried out with x-ray photoemission spectroscopy. Optical-quality crystal α-SrB4O7 has been grown by the Czochralski method. Detailed photoemission spectra of the element core levels have been recorded from the powder sample under excitation by nonmonochromatic Al Kα radiation (1486.6 eV). The band structure of α-SrB4O7 has been calculated by ab initio methods and compared to XPS measurements. It has been found that the band structure of α-SrB4O7 is weakly dependent on the Sr-related states.

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

USGS Publications Warehouse

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

2005-01-01

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

Acigöl rhyolite field, central Anatolia (part II): geochemical and isotopic (Sr-Nd-Pb, δ18O) constraints on volcanism involving two high-silica rhyolite suites

NASA Astrophysics Data System (ADS)

Siebel, W.; Schmitt, A. K.; Kiemele, E.; Danišík, M.; Aydin, F.

2011-12-01

The Acigöl rhyolite field erupted the most recent high-silica rhyolites within the Cappadocian Volcanic Province of central Anatolia, Turkey. It comprises two sequences of domes and pyroclastic rocks with eruption ages of ~150-200 ka (eastern group) and ~20-25 ka (western group). Compositionally, the eastern rhyolite group lavas are less evolved (SiO2 = 74-76 wt%), whereas the western group has higher silica abundance (SiO2 = ~77 wt%) with extremely depleted feldspar-compatible trace elements. Within each group, compositional variability is small and 143Nd/144Nd (0.51257-0.51265) and Pb isotope compositions (206Pb/204Pb = 18.87-18.88, 207Pb/204Pb = 15.65-15.67 and 208Pb/204Pb = 38.94-38.98) are homogeneous. The western group rhyolites have δ18O(zircon) overlapping mantle values (5.7 ± 0.2‰), whereas eastern group rhyolites are enriched in δ18O by ~0.5‰, consistent with a tendency to lower ɛNd values. By contrast, western group rhyolites have markedly more radiogenic 87Sr/86Sr ratios (0.7065-0.7091) compared to those of the eastern group (0.7059-0.7065). The presence of angular granitic xenoliths and a correlation between hydration (based on loss on ignition data) and 87Sr/86Sr in the western lavas, however, indicates that Sr was added during the eruption or post-eruption alteration. Isotope constraints preclude the possibility that the rhyolite magmas formed by partial melting of any known regional crystalline basement rocks. Basalts and andesites erupted in the periphery of the Acigöl field are characterised by 87Sr/86Sr ratios between 0.7040 and 0.7053, 143Nd/144Nd = 0.51259-0.51300, 206Pb/204Pb = 18.85-18.87, 207Pb/204Pb = 15.646-15.655, 208Pb/204Pb = 38.90-38.97. The isotopic and trace element data favour an origin of the rhyolites by mixing of basaltic/andesitic magmas with minor amounts of crustal melts and followed by extensive fractional crystallization.

Synchrotron Radiation Workshop (SRW)

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

Chubar, O.; Elleaume, P.

2013-03-01

"Synchrotron Radiation Workshop" (SRW) is a physical optics computer code for calculation of detailed characteristics of Synchrotron Radiation (SR) generated by relativistic electrons in magnetic fields of arbitrary configuration and for simulation of the radiation wavefront propagation through optical systems of beamlines. Frequency-domain near-field methods are used for the SR calculation, and the Fourier-optics based approach is generally used for the wavefront propagation simulation. The code enables both fully- and partially-coherent radiation propagation simulations in steady-state and in frequency-/time-dependent regimes. With these features, the code has already proven its utility for a large number of applications in infrared, UV, softmore » and hard X-ray spectral range, in such important areas as analysis of spectral performances of new synchrotron radiation sources, optimization of user beamlines, development of new optical elements, source and beamline diagnostics, and even complete simulation of SR based experiments. Besides the SR applications, the code can be efficiently used for various simulations involving conventional lasers and other sources. SRW versions interfaced to Python and to IGOR Pro (WaveMetrics), as well as cross-platform library with C API, are available.« less

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.

Quantifying the impact of riverine particulate dissolution in seawater on ocean chemistry

NASA Astrophysics Data System (ADS)

Jones, Morgan T.; Gislason, Sigurður R.; Burton, Kevin W.; Pearce, Christopher R.; Mavromatis, Vasileios; Pogge von Strandmann, Philip A. E.; Oelkers, Eric H.

2014-06-01

The quantification of the sources and sinks of elements to the oceans forms the basis of our understanding of global geochemical cycles and the chemical evolution of the Earth's surface. There is, however, a large imbalance in the current best estimates of the global fluxes to the oceans for many elements. In the case of strontium (Sr), balancing the input from rivers would require a much greater mantle-derived component than is possible from hydrothermal water flux estimates at mid-ocean ridges. Current estimates of riverine fluxes are based entirely on measurements of dissolved metal concentrations, and neglect the impact of riverine particulate dissolution in seawater. Here we present 87Sr/86Sr isotope data from an Icelandic estuary, which demonstrate rapid Sr release from the riverine particulates. We calculate that this Sr release is 1.1-7.5 times greater than the corresponding dissolved riverine flux. If such behaviour is typical of volcanic particulates worldwide, this release could account for 6-45% of the perceived marine Sr budget imbalance, with continued element release over longer timescales further reducing the deficit. Similar release from particulate material will greatly affect the marine budgets of many other elements, changing our understanding of coastal productivity, and anthropogenic effects such as soil erosion and the damming of rivers.

The variable role of slab-derived fluids in the generation of a suite of primitive calc-alkaline lavas from the Southernmost Cascades, California

USGS Publications Warehouse

Borg, L.E.; Clynne, M.A.; Bullen, T.D.

1997-01-01

The compositional continuum observed in primitive calc-alkaline lavas erupted from small volcanoes across the southernmost Cascade arc is produced by the introduction of a variable proportion of slab-derived fluid into the superjacent peridotite layer of the mantle wedge. Magmas derived from fluid-rich sources are erupted primarily in the forearc and are characterized by Sr and Pb enrichment (primitive mantle-normalized Sr/P > 5.5), depletions of Ta and Nb, low incompatible-element abundances, and MORB-like Sr and Pb isotopic ratios. Magmas derived from fluid-poor sources are erupted primarily in the arc axis and behind the arc, and are characterized by weak enrichment in Sr [1.0 < (Sr/P)N < 1.3], weak depletions in Ta and Nb, higher incompatible-element abundances, and OIB-like Sr, Nd, and Pb isotopic ratios. Fluxing the mantle wedge above the subducting slab with H2O-rich fluid stabilizes amphibole and enriches the wedge peridotites in incompatible elements, particularly unradiogenic Sr and Pb. The hydrated amphibole-bearing portion of the mantle wedge is downdragged beneath the forearc, where its solidus is exceeded, yielding melts that are enriched in Sr and Pb, and depleted in Ta and Nb (reflecting both high Sr and Pb relative to Ta and Nb in the fluid, and the greater compatibility of Ta and Nb in amphibole compared to other silicate phases in the wedge). A steady decrease of the fluid-contributed geochemical signature away from the trench is produced by the progressive dehydration of the downdragged portion of the mantle wedge with depth, resulting from melt extraction and increased temperature at the slab-wedge interface. Inverse correlation between incompatible-element abundances and the size of the fluid-contributed geochemical signature is generated by melting of more depleted peridotites, rather than by significant differences in the degree of melting. High-(Sr/P)N lavas of the forearc are generated by melting of a MORB-source-like peridotite that has been fluxed with a greater proportion of slab-derived fluid, and low (Sr/P)N lavas of the arc axis are produced by melting of an OIB-source-like peridotite in the presence of a smaller proportion of slab-derived fluid. This study documents the control that a slab-derived fluid can have on incompatible element and isotopic systematics of arc magmas by 1) the addition of incompatible elements to the wedge, 2) the stabilization of hydrous phases in the wedge, and 3) the lowering of peridotite solidi.

Evolution of the lithospheric mantle beneath Mt. Baekdu (Changbaishan): Constraints from geochemical and Sr-Nd-Hf isotopic studies on peridotite xenoliths in trachybasalt

NASA Astrophysics Data System (ADS)

Park, Keunsu; Choi, Sung Hi; Cho, Moonsup; Lee, Der-Chuen

2017-08-01

Major and trace element compositions of minerals as well as Sr-Nd-Hf isotopic compositions of clinopyroxenes from spinel peridotite xenoliths entrained in Late Cenozoic trachybasalt from Mt. Baekdu (Changbaishan) were used to elucidate lithospheric mantle formation and evolution in the eastern North China Craton (NCC). The analyzed peridotites were mainly spinel lherzolites with rare harzburgites. They consisted of olivine (Fo89.3-91.0), enstatite (Wo1-2En88-90Fs8-11), diopside (Wo45-50En45-51Fs4-6), and spinel (Cr# = 8.8-54.7). The peridotite residues underwent up to 25% partial melting in fertile mid-ocean-ridge basalt (MORB) mantle. Plots of the Cr# in spinel against the Mg# in coexisting olivine or spinel suggested an affinity with abyssal peridotites. Comparisons of Cr# and TiO2 in spinel were also compatible with an abyssal peridotite-like composition; however, harzburgites were slightly enriched in TiO2 because of the reaction with MORB-like melt. Temperatures estimated using two-pyroxene thermometry ranged from 750 to 1010 °C, reflecting their lithospheric mantle origin. The rare earth element (REE) patterns in clinopyroxenes of the peridotites varied from light REE (LREE) depleted to spoon shaped to LREE enriched, reflecting secondary overprinting effects of metasomatic melts or fluids on the residues from primordial melting. The calculated trace element pattern of metasomatic melt equilibrated with clinopyroxene in Mt. Baekdu peridotite showed strong enrichment in large-ion lithophile elements, Th and U together with slight fractionation in heavy REEs (HREEs) and considerable depletion in Nb and Ti. The Sr-Nd-Hf isotopic compositions of clinopyroxenes separated from the peridotites varied from more depleted than present-day MORB to bulk Earth values. However, some clinopyroxene showed a decoupling between Nd and Sr isotopes, deviating from the mantle array with a high 87Sr/86Sr ratio. This sample also showed a significant Nd-Hf isotope decoupling lying well above the mantle array. The Lu-Hf and Sm-Nd model ages of residual clinopyroxenes yielded Early Proterozoic to Phanerozoic ages. No signature of Archean cratonic mantle was present. Therefore, Mt. Baekdu peridotite is residual lithospheric mantle that has undergone variable degrees of diachronous melt extraction and infiltration metasomatism involving subduction-related, fluid-bearing silicate melts. The predominance of Phanerozoic Hf model ages indicates that the lherzolites represent lithospheric mantle fragments newly accreted underneath the eastern NCC.

Sr and U isotope ratios in soil waters as tracers of weathering dynamic in soils (Strengbach catchment - Vosges-mountains; France).

NASA Astrophysics Data System (ADS)

Chabaux, François; Prunier, Jonathan; Pierret, Marie-Claire; Stille, Peter

2013-04-01

It is proposed in this study to highlight the interest of multi-tracer geochemical approaches combining measurement of major and trace element concentrations along with U and Sr isotopic ratios to constrain the characterization of the present-day weathering processes controlling the chemical composition of waters and soils in natural ecosystems. This is important if we want to predict and to model correctly the response of ecosystems to recent environmental changes. The approach is applied to the small granitic Strengbah Catchment, located in the Vosges Mountain (France), used and equipped as a hydro-geochemical observatory since 1986 (Observatoire Hydro-Géochimique de l'Environnement; http://ohge.u-strasbg.fr). This study includes the analysis of major and trace element concentrations and (U-Sr) isotope ratios in soil solutions collected within two soil profiles located on two experimental plots of this watershed, along with the analysis of soil samples and vegetation samples from these two plots. The depth variation of elemental concentrations of soil solutions confirms the important influence of the vegetation cycling on the budget of Ca, K, Rb and Sr, whereas Mg and Si budget in soil solutions are quasi exclusively controlled by weathering processes. Variation of Sr, and U isotopic ratios with depth also demonstrates that the sources and biogeochemical processes controlling the Sr budget of soil solutions is different in the uppermost soil horizons and in the deeper ones, and clearly influence by the vegetation cycling. From the obtained data, it can be therefore proposed a scheme where in addition to the external flux associated to the decomposition of organic matter and throughfall, occurs a double lithogenic flux: a surface flux which can be associated to dissolution of secondary minerals contained in fine silt fractions and a deeper one, controlled by water-rock interactions which can mobilize elements from primary minerals like plagioclases or orthose. These results shows also that the Strengbach watershed is in a transient state of weathering with an important loss of nutriments such as Ca in soils solutions since 15years, associated with an increase of a lithogenic flux indicating a recent modification of weathering/dissolution reactions involved in the soil horizons. The origin of the weathering modification could be the consequence of the acid rains on weathering granitic bedrock or a consequence of forest exploitation incompatible with the nutriment reserve of soils with recent plantations of conifer, which impoverish soils.

Development of biodegradable Zn-1X binary alloys with nutrient alloying elements Mg, Ca and Sr.

PubMed

Li, H F; Xie, X H; Zheng, Y F; Cong, Y; Zhou, F Y; Qiu, K J; Wang, X; Chen, S H; Huang, L; Tian, L; Qin, L

2015-05-29

Biodegradable metals have attracted considerable attentions in recent years. Besides the early launched biodegradable Mg and Fe metals, Zn, an essential element with osteogenic potential of human body, is regarded and studied as a new kind of potential biodegradable metal quite recently. Unfortunately, pure Zn is soft, brittle and has low mechanical strength in the practice, which needs further improvement in order to meet the clinical requirements. On the other hand, the widely used industrial Zn-based alloys usually contain biotoxic elements (for instance, ZA series contain toxic Al elements up to 40 wt.%), which subsequently bring up biosafety concerns. In the present work, novel Zn-1X binary alloys, with the addition of nutrition elements Mg, Ca and Sr were designed (cast, rolled and extruded Zn-1Mg, Zn-1Ca and Zn-1Sr). Their microstructure and mechanical property, degradation and in vitro and in vivo biocompatibility were studied systematically. The results demonstrated that the Zn-1X (Mg, Ca and Sr) alloys have profoundly modified the mechanical properties and biocompatibility of pure Zn. Zn-1X (Mg, Ca and Sr) alloys showed great potential for use in a new generation of biodegradable implants, opening up a new avenue in the area of biodegradable metals.

Development of biodegradable Zn-1X binary alloys with nutrient alloying elements Mg, Ca and Sr

PubMed Central

Li, H. F.; Xie, X. H.; Zheng, Y. F.; Cong, Y.; Zhou, F. Y.; Qiu, K. J.; Wang, X.; Chen, S. H.; Huang, L.; Tian, L.; Qin, L.

2015-01-01

Biodegradable metals have attracted considerable attentions in recent years. Besides the early launched biodegradable Mg and Fe metals, Zn, an essential element with osteogenic potential of human body, is regarded and studied as a new kind of potential biodegradable metal quite recently. Unfortunately, pure Zn is soft, brittle and has low mechanical strength in the practice, which needs further improvement in order to meet the clinical requirements. On the other hand, the widely used industrial Zn-based alloys usually contain biotoxic elements (for instance, ZA series contain toxic Al elements up to 40 wt.%), which subsequently bring up biosafety concerns. In the present work, novel Zn-1X binary alloys, with the addition of nutrition elements Mg, Ca and Sr were designed (cast, rolled and extruded Zn-1Mg, Zn-1Ca and Zn-1Sr). Their microstructure and mechanical property, degradation and in vitro and in vivo biocompatibility were studied systematically. The results demonstrated that the Zn-1X (Mg, Ca and Sr) alloys have profoundly modified the mechanical properties and biocompatibility of pure Zn. Zn-1X (Mg, Ca and Sr) alloys showed great potential for use in a new generation of biodegradable implants, opening up a new avenue in the area of biodegradable metals. PMID:26023878

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.

Elemental and Sr-Nd isotopic geochemistry of the Uradzhongqi magmatic complex in western Inner Mongolia, China: A record of early Permian post-collisional magmatism

NASA Astrophysics Data System (ADS)

Qiao, Xueyuan; Li, Wenbo; Zhong, Richen; Hu, Chuansheng; Zhu, Feng; Li, Zhihua

2017-08-01

The magmatic complex in Uradzhongqi, Inner Mongolia, is located in the western segment of the northern margin of the North China Craton (NCC). The dominant components in the complex include syenogranite, monzogranite, granodiorite, diorite and gabbro. Mafic microgranular enclaves (MMEs) are common in syenogranite and granodiorite. Zircon U-Pb dating shows that the ages of these rocks range from 283 to 270 Ma, suggesting an early Permian emplacement. The syenogranite and monzogranite are peraluminous I-type granites, exhibiting conspicuous negative Eu anomaly, enrichment in large-ion lithophile elements (LILE) and light rare earth elements (LREE), depletion in high field strength elements (HFSE). The granodiorites, diorites and MMEs are metaluminous in composition, show high Al2O3, MgO and Fe2O3T contents and weak negative Eu anomaly, as well as LREE and LILE enrichment and HFSE depletion. The gabbros show weak positive Eu anomaly and slight REE differentiation. The Sr-Nd isotope compositions show that the source of mafic magma was depleted mantle (DM) with possible involvement of enriched mantle II (EM II), whereas the felsic magma was derived from the Archean lower crust. Petrographic observation and analytical results of mineralogy, geochronology, geochemistry and Sr-Nd isotopes indicate that the main petrogenesis of these magmatic rocks is the mixing of underplating mafic magma and felsic magma. Tectonically, the complex pluton was formed within a post-collisional regime, and the underplating in this area provides another piece of evidence for the vertical growth of the western segment of the northern margin of the NCC.

High-Resolution Synchrotron Radiation Imaging of Trace Metal Elemental Concentrations in Porites Coral

NASA Astrophysics Data System (ADS)

Cirino, M.; Dunbar, R. B.; Tangri, N.; Mehta, A.

2014-12-01

We investigated the use of synchrotron radiation for elemental imaging within the skeleton of a Porites coral from American Samoa to explore the fine-scale structure of strontium to calcium (Sr/Ca) variability. The use of a synchrotron for coral paleoclimate analysis is relatively new. The method provides a high resolution, two-dimensional elemental map of a coral surface. The aragonitic skeleton of Porites sp. colonies has been widely used for paleoclimate reconstruction as the oxygen isotope ratio (δ18O) signal varies with both sea surface temperature (SST) and sea surface salinity (SSS). Sr/Ca has been used in previous studies in conjunction with δ18O to deconvolve SST from SSS, as Sr/Ca in the coral skeleton varies with SST, but not SSS. However, recent studies suggest that in some cases Sr/Ca variability in coral does not reliably reflect changes in SST. We sought to address this puzzle by investigating Sr/Ca variability in Porites corals at a very fine spatial scale while also demonstrating the suitability of the synchrotron as a coral analysis tool. We also considered Sr/Ca variability as it pertains to the coral's structural elements. The Stanford Linear Accelerator Center synchrotron station generates collimated x-rays in the energy range of 4500-45000 eV with beam diameters as small as 20 μm. Synchrotron imaging allows faster and higher-resolution Sr/Ca analysis than does inductively coupled plasma mass spectrometry (ICP-MS). It also is capable of mapping spatial distributions of many elements, which aids in the development of a multiproxy approach to paleoclimate reconstruction. Imaging and analysis of the Porites coral using synchrotron radiation revealed an intricate sub-seasonal Sr/Ca signal, possibly correlating to a sub-monthly resolution. This signal, which seems unrelated to SST, dominates the annual signal.

Elemental signatures in otoliths of hatchery rainbow trout (Oncorhynchus mykiss): Distinctiveness and utility fo detecting origins and movement

USGS Publications Warehouse

Gibson-Reinemer, D. K.; Johnson, B.M.; Martinez, P.J.; Winkelman, D.L.; Koenig, A.E.; Woodhead, J.D.

2009-01-01

Otolith chemistry in freshwater has considerable potential to reveal patterns of origin and movement, which would benefit traditional fisheries management and provide a valuable tool to curb the spread of invasive and illicitly stocked species. We evaluated the relationship between otolith and water chemistry for five markers (Ba/Ca, Mn/Ca, Sr/ Ca, Zn/Ca, and 87Sr/86Sr) in rainbow trout (Oncorhynchus mykiss) using the existing hatchery system in Colorado and Wyoming, USA, to provide controlled, seminatural conditions. Otolith Ba/Ca, Sr/Ca, and 87Sr/86Sr reflected ambient levels, whereas Mn/Ca and Zn/Ca did not. Using only the markers correlated with water chemistry, we classified fish to their hatchery of origin with up to 96% accuracy when element and isotope data were used together. Large changes in 87Sr/Sr were evident in otolith transects, although subtler changes in Sr/Ca were also detectable. Our results suggest the relatively few otolith markers that reflect ambient chemistry can discriminate among locations and track movements well enough to provide valuable insight in a variety of applied contexts.

A methodology for quantifying trace elements in the exoskeletons of Florida stone crab (Menippe mercenaria) larvae using inductively coupled plasma optical emission spectrometry (ICP–OES)

USGS Publications Warehouse

Gravinese, Philip M.; Flannery, Jennifer A.; Toth, Lauren T.

2016-11-23

The larvae of the Florida stone crab, Menippe mercenaria, migrate through a variety of habitats as they develop and, therefore, experience a broad range of environmental conditions through ontogeny. Environmental variability experienced by the larvae may result in distinct elemental signatures within the exoskeletons, which could provide a tool for tracking the environmental history of larval stone crab populations. A method was developed to examine trace-element ratios, specifically magnesium-to-calcium (Mg/Ca) and strontium-to-calcium (Sr/Ca) ratios, in the exoskeletons of M. mercenaria larvae. Two developmental stages of stone crab larvae were analyzed—stage III and stage V. Specimens were reared in a laboratory environment under stable conditions to quantify the average ratios of Mg/Ca and Sr/Ca of larval stone crab exoskeletons and to determine if the ratios differed through ontogeny. The elemental compositions (Ca, Mg, and Sr) in samples of stage III larvae (n = 50 per sample) from 11 different broods (mean Sr/Ca = 5.916 ± 0.161 millimole per mole [mmol mol−1]; mean Mg/Ca = 218.275 ± 59.957 mmol mol−1) and stage V larvae (n = 10 per sample) from 12 different broods (mean Sr/Ca = 6.110 ± 0.300 mmol mol−1; mean Mg/Ca = 267.081 ± 67.211 mmol mol–1) were measured using inductively coupled plasma optical emission spectrometry (ICP–OES). The ratio of Sr/Ca significantly increased from stage III to stage V larvae, suggesting an ontogenic shift in Sr/Ca ratios between larval stages. The ratio of Mg/Ca did not change significantly between larval stages, but variability among broods was high. The method used to examine the trace-element ratios provided robust, highly reproducible estimates of Sr/Ca and Mg/Ca ratios in the larvae of M. mercenaria, demonstrating that ICP–OES can be used to determine the trace-element composition of chitinous organisms like the Florida stone crab.

Modification of Ca isotope and trace metal composition of the major matrices involved in shell formation of Mytilus edulis

NASA Astrophysics Data System (ADS)

Heinemann, Agnes; Fietzke, Jan; Eisenhauer, Anton; Zumholz, Karsten

2008-01-01

In this study we present the first combined investigation into the composition of the major matrices involved in calcification processes (surrounding water, extrapallial fluid, aragonite, and calcite) of Mytilus edulis with respect to their calcium isotope (δ44/40Ca) and elemental compositions (Sr/Ca and Mg/Ca). Our aim was to examine the suitability of Mytilus edulis as a proxy archive and to contribute to the understanding of the process of biomineralization. Mytilus edulis specimens were live collected from the Schwentine Estuary, Kiel Fjord, and North Sea (Sylt). δ44/40Ca was determined by thermal ionization mass spectrometry (TIMS) accompanied by measurements of Mg/Ca and Sr/Ca using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The elemental and isotopic compositions of the investigated matrices showed systematic offsets. The carbonates are strongly depleted in their magnesium and strontium concentrations and fractionated toward lighter calcium isotope compositions relative to the surrounding Schwentine Estuary water. The opposite is observed for the extrapallial fluid (EPF). Our findings extend the results of previous studies reporting a strong biological control and the interaction of different environmental conditions influencing biomineralization. Future studies should focus on the temporal development of the interrelation between the different matrices.

Sr - an element shows the way - Applications of Sr isotopes for provenance, tracing and migration (Invited)

NASA Astrophysics Data System (ADS)

Prohaska, T.; Irrgeher, J.; Zitek, A.; Teschler Nicola, M.

2010-12-01

Strontium - named after the small Scottish town Strontian - as such is an element with little popularity. Firstly described by Martin Heinrich Klaproth in 1798, the metal is used in metallurgy to some extent whereas its compounds are interesting in glass industries, electronics and pyrotechnics. The element has chemical similarity to Ca and makes up 1/60 of the earth’s amount of the latter. Nonetheless, it is its isotopic composition which makes Sr so interesting for a large number of scientists. The natural composition of the four naturally occurring isotopes (84Sr, 86Sr 87Sr and 88Sr) varies in nature due to the radioactive decay of 87Rb to 87Sr. Thus, it was early recognized as geochronometer especially in Ca rich matrices. With increasing precision of applied methodology, the natural variation of the 87Sr/86Sr isotope ratio (analyzed at first mainly by thermal ionization mass spectrometry (TIMS)) became more and more popular in provenance studies. The natural variation of the ratio is mainly determined by the geological age and the original composition of the rock and can be used therefore as fingerprint of the local geology. The ratio is transferred with no significant fractionation via the water into plants and finally via the food chain into animal and human tissues (especially bones and teeth). As the element is chemically similar to Ca, it appears in most matrices. The use for provenance studies is supported by the fact that the long half life (4.8 x 1010 years) does not lead to an alteration during the time scales which are investigated (from recent samples to human or animal skeletal remains which date back up to 30.000 BC). The uniqueness of the system besides the natural variation is defined by the ubiquity in nature and the relatively high (and thus measurable) elemental concentration in most tissues. It was finally the advent of multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) which augmented the number of applications presented for Sr isotope ratios simply supported by the fact that a higher statistical number of samples could be analyzed. Further supported by direct introductions systems such as laser ablation, the popularity of Sr in science has increased steadily. A number of fields of applications make nowadays use of the system so far: anthropology and archaeology as well as food science, chemical technology, forensic science, medicine or biology. The Sr isotope system will be presented along with analytical techniques applied. Selected examples making use of the natural Sr isotopic variation will be reported: Proof of provenance of food, forensic applications and migration studies on prehistoric cultures or modern biological systems. In addition, the application of enriched Sr isotope spikes will be presented. The spikes are administered in order to investigate Sr turnovers (e.g. as proxy for Ca in biomedical studies), marking tissues for tracing and migration experiments and investigating environmental processes.

Measurement of trace elements in tree rings using the PIXE method

NASA Astrophysics Data System (ADS)

Aoki, Toru; Katayama, Yukio; Kagawa, Akira; Koh, Susumu; Yoshida, Kohji

1998-03-01

Standard materials were prepared in order to calculate element concentrations in tree samples using the particle induced X-ray emission (PIXE) method. Five standard solutions (1) Ti, Fe, Cu, As, Rb, Sr; (2) Ca, V, Co, Zn, As, Rb; (3) Ti, Mn, Ni, As, Sr; (4) K, Mn, Co, As, Rb, Sr; and (5) Ca, Mn, Cu, As, Rb, Sr, were added to filter papers. The dried filter papers were used as standard samples. Pellets of Pepperbush leaves (National Institute for Environmental Studies (NIES)) and Peach leaves (National Institute of Standards and Technology (NIST)) were used as references. The peak counts of Ca, Mn, Cu, Zn, Rb, and Sr in samples taken from a kaki ( Diospros kaki Thunb.) were measured and the concentrations (ppm) of the elements were calculated using the yield curve obtained from the standard filter papers. The concentrations of Mn, Zn, Rb, and Ca were compared with the data obtained from a separate INAA analysis. Concentrations of Mn, Zn, and Ca obtained by both methods were almost the same, but the concentrations of Rb differed slightly. The amounts of trace elements in samples taken from a sugi ( Cryptomeria japonica D. Don) were also measured.

Application of LA-MC-ICP-MS for analysis of Sr isotope ratios in speleothems

NASA Astrophysics Data System (ADS)

Weber, Michael; Scholz, Denis; Wassenburg, Jasper A.; Jochum, Klaus Peter; Breitenbach, Sebastian

2017-04-01

Speleothems are well established climate archives. In order to reconstruct past climate variability, several geochemical proxies, such as δ13C and δ18O as well as trace elements are available. Since several factors influence each individual proxy, robust interpretation is often hampered. This calls for multi-proxy approaches involving additional isotope systems that can help to delineate the role of different sources of water within the epikarst and changes in soil composition. Sr isotope ratios (87Sr/86Sr) have been shown to provide useful information about water residence time and water mixing in the host rock. Furthermore, Sr isotopes are not fractionated during calcite precipitation, implying that the 87Sr/86Sr ratio of the speleothem provides a direct record of the drip water. While most speleothem studies applying Sr isotopes used the TIMS methodology, LA-MC-ICP-MS has been utilized for several other archives, such as otoliths and teeth. This method provides the advantage of faster data acquisition, higher spatial resolution, larger sample throughput and the absence of chemical treatment prior to analysis. Here we present the first LA-MC-ICP-MS Sr isotope data for speleothems. The analytical uncertainty of our LA-MC-ICP-MS Sr data is in a similar range as for other carbonate materials. The results of different ablation techniques (i.e. line scan and spots) are reproducible within error, implying that the application of this technique on speleothems is possible. In addition, several comparative measurements of different carbonate reference materials (i.e. MACS-3, JCt-1, JCp-1), such as tests with standard bracketing and comparison of the 87Sr/86Sr ratios with nanosecond laser ablation system and a state-of-the-art femtosecond laser ablation system, show the robustness of the method. We applied the method to samples from Morocco (Grotte de Piste) and India (Mawmluh Cave). Our results show only very small changes in the 87Sr/86Sr ratios of both speleothems. However, one speleothem from Mawmluh Cave shows a slight increase of 87Sr/86Sr within the error, which is reproducible with line scans and spots.

The isotopic and chemical evolution of Mount St. Helens

USGS Publications Warehouse

Halliday, A.N.; Fallick, A.E.; Dickin, A.P.; Mackenzie, A.B.; Stephens, W.E.; Hildreth, W.

1983-01-01

Isotopic and major and trace element analysis of nine samples of eruptive products spanning the history of the Mt. St. Helens volcano suggest three different episodes; (1) 40,000-2500 years ago: eruptions of dacite with ??{lunate}Nd = +5, ??{lunate}Sr = -10, variable ??18O, 206Pb/204Pb ??? 18.76, Ca/Sr ??? 60, Rb/Ba ??? 0.1, La/Yb ??? 18, (2) 2500-1000 years ago: eruptions of basalt, andesite and dacite with ??{lunate}Nd = +4 to +8, ??{lunate}Sr = -7 to -22, variable ??18O (thought to represent melting of differing mantle-crust reservoirs), 206Pb/204Pb = 18.81-18.87, variable Ca/Sr, Rb/Ba, La/Yb and high Zr, (3) 1000 years ago to present day: eruptions of andesite and dacite with ??{lunate}Nd = +6, ??{lunate}Sr = -13, ??18O ???6???, variable 206Pb/204Pb, Ca/Sr ??? 77, Rb/Ba = 0.1, La/Yb ??? 11. None of the products exhibit Eu anomalies and all are LREE enriched. There is a strong correlation between 87Sr/86Sr and differentiation indices. These data are interpreted in terms of a mantle heat source melting young crust bearing zircon and garnet, but not feldspar, followed by intrusion of this crustal reservoir by mantle-derived magma which caused further crustal melting and contaminated the crustal magma system with mafic components. Since 1000 years ago all the eruptions have been from the same reservoir which has displayed a much more gradual re-equilibration of Pb isotopic compositions than other components suggesting that Pb is being transported via a fluid phase. The Nd and Sr isotopic compositions lie along the mantle array and suggest that the mantle underneath Mt. St. Helens is not as depleted as MORB sources. There is no indication of seawater involvement in the source region. ?? 1983.

Veined pyroxenite xenoliths in Ugandan kamafugites: mantle or magma? Using in situ techniques for 87Sr/86Sr-isotopes and trace elements as tools

NASA Astrophysics Data System (ADS)

Link, Klemens; Tommasini, Simone; Braschi, Eleonora; Conticelli, Sandro; Barifaijo, Erasmus; Tiberindwa, John V.; Foley, Stephen F.

2010-05-01

The genesis of pyroxenite nodules in Ugandan kamafugites and their possible genetic relationships is a matter of debate. In earlier studies the pyroxenites were considered either as xenoliths from pervasively metasomatized peridotite mantle (Lloyd, 1981) or as distinct paragenesises occurring as veins within the peridotitic mantle (Harte et al., 1993). In both cases the xenoliths would represent mantle material that was at least partly involved as source material for the kamafugite melts. A third alternative could be that they represent cumulates of the lavas. In any case, the nodules provide important information for understanding the generation of ultrapotassic lavas and for characterizing the rift-related lithosphere mantle as part of the initial continental rift process. Originally the ultrapotassic kamafugites were considered to be single stage partial melts of pervasively metasomatized mantle but new geochemical studies indicate a multistage development (Rosenthal et al., 2009). Nd, Hf and Os isotopes point to mixing between components derived from metasomatically influenced peridotite and mica-pyroxenite. In-situ investigation of the Sr-isotope and trace element compositions of individual minerals in a number of xenoliths allows us to constrain their genesis and relation to the host lavas. The nodules appear to originate by near-liquidus crystallization of melts derived from enriched peridotite within the cratonic lithosphere mantle. They later partially remelted to form one source of the potassium-rich kamafugites. Sr-isotopes from different domains within single mineral grains in the nodules and host lavas are used to trace the nodules' role as a potential source to lavas, and trace element measurements are used to support the conclusions. Rb/Sr- measurements from the biotites to constrain the time between nodule crystallization and eruption of the Quaternary lavas to about 3.3 Ma. This also suggests a significant increase of the geothermal gradient beneath the preceding rift within that time. Structures on microscopic scale indicate at least two different generations of mineral growth clearly related to multiphase magmatic events forming the nodules. Rare composite samples allow a correlation between the older and younger parageneses, demonstrating reaction between the older matrix pyroxenite and the younger, high-Ti melt. The relatively low (~0,13wt%) Cr2O3-contents together with the high LREE concentrations measured in the oldest observed clinopyroxenes (La~12,4 x PRIMA with La/Lu~21) as well as the lack of any other characteristic mineral relicts argue against a pervasively overprinted peridotite mantle. Comparable 87Sr/86Sr- values close to bulk earth values as well as similar 143Nd/144Nd- ratios in the nodules (0,512480-0,5122573) and the lavas (average: 0,512551) support a genetic link between the kamafugites and the nodules as suggested by experiments (Lloyd et al. 1985). Low radiogenic 87Sr/86Sr ratios in Rb-free clinopyroxene and perovskite (0,704459-0,704487) constrain initial values for the source whereas slightly more radiogenic values from cogenetic Rb-bearing biotites (0,704754- 0,704762) are the result of radioactive decay after mineral growth. The majority of the kamafugite 87Sr/86Sr values lie between the two end-members (0,704624- 0,704717). Additionally considering microscale structures showing melting processes we conclude that the nodules represent one source and that the intermediate 87Sr/86Sr values of the lavas reflect the melting of differing proportions of biotite and clinopyroxene in the source region.

Spatial distribution of the trace elements zinc, strontium and lead in human bone tissue☆

PubMed Central

Pemmer, B.; Roschger, A.; Wastl, A.; Hofstaetter, J.G.; Wobrauschek, P.; Simon, R.; Thaler, H.W.; Roschger, P.; Klaushofer, K.; Streli, C.

2013-01-01

Trace elements are chemical elements in minute quantities, which are known to accumulate in the bone. Cortical and trabecular bones consist of bone structural units (BSUs) such as osteons and bone packets of different mineral content and are separated by cement lines. Previous studies investigating trace elements in bone lacked resolution and therefore very little is known about the local concentration of zinc (Zn), strontium (Sr) and lead (Pb) in BSUs of human bone. We used synchrotron radiation induced micro X-ray fluorescence analysis (SR μ-XRF) in combination with quantitative backscattered electron imaging (qBEI) to determine the distribution and accumulation of Zn, Sr, and Pb in human bone tissue. Fourteen human bone samples (10 femoral necks and 4 femoral heads) from individuals with osteoporotic femoral neck fractures as well as from healthy individuals were analyzed. Fluorescence intensity maps were matched with BE images and correlated with calcium (Ca) content. We found that Zn and Pb had significantly increased levels in the cement lines of all samples compared to the surrounding mineralized bone matrix. Pb and Sr levels were found to be correlated with the degree of mineralization. Interestingly, Zn intensities had no correlation with Ca levels. We have shown for the first time that there is a differential accumulation of the trace elements Zn, Pb and Sr in BSUs of human bone indicating different mechanisms of accumulation. PMID:23932972

Compositional gradients in large reservoirs of silicic magma as evidenced by ignimbrites versus Taylor Creek Rhyolite lava domes

NASA Astrophysics Data System (ADS)

Duffield, Wendell A.; Ruiz, Joaquin

1992-04-01

The Taylor Creek Rhyolite of southwest New Mexico consists of 20 lava domes and flows that were emplaced during a period of a few thousand years or less in late Oligocene time. Including genetically associated pyroclastic deposits, which are about as voluminous as the lava domes and flows, the Taylor Creek Rhyolite represents roughly 100 km3 of magma erupted from vents distributed throughout an area of several hundred square kilometers. Major-element composition is metaluminous to weakly peraluminous high-silica rhyolite and is nearly constant throughout the lava field. The magma reservoir for the Taylor Creek Rhyolite was vertically zoned in trace elements, 87Sr/86Sr, and phenocryst abundance and size. Mean trace-element concentrations, ranges in concentrations, and element-pair correlations are similar to many subalkaline silicic ignimbrites. However, the polarity of the zonation was opposite that in reservoirs for ignimbrites, for most constituents. For example, compared to the Bishop Tuff, only 87Sr/86Sr and Sc increased upward in both reservoirs. Quite likely, a dominant but nonerupted volume of the magma reservoir for the Taylor Creek Rhyolite was zoned like that for the Bishop Tuff, whereas an erupted, few-hundred-meter-thick cap on the magma body was variably contaminated by roof rocks whose contribution to this part of the magma system moderated relatively extreme trace-element concentrations of uncontaminated Taylor Creek Rhyolite but did not change the sense of correlation for most element pairs. The contaminant probably was a Precambrian rock of broadly granitic composition and with very high 87Sr/86Sr. Although examples apparently are not yet reported in the literature, evidence for a similar thin contaminated cap on reservoirs for large-volume silicic ignimbrites may exist in the bottom few meters of ignimbrites or perhaps only in the pumice fallout that normally immediately precedes ignimbrite emplacement. 87Sr/86Sr in sanidine phenocrysts of the Taylor Creek Rhyolite is higher than that of their host whole rocks. Covariation of this isotope ratio with sanidine abundance and size indicates positive correlations for all three features with decreasing distance to the roof of the magma reservoir. The sanidine probably is more radiogenic than host whole rock because growing phenocrysts partly incorporated Sr from the first partial melt of roof rocks, which contained the highly radiogenic Sr of Precambrian biotite ± hornblende, whereas diffusion was too slow for sanidine to incorporate much of the Sr from subsequently produced less radiogenic partial melt of roof rocks, before eruption quenched the magma system. Disequilibrium between feldspar phenocrysts and host groundmass is fairly common for ignimbrites, and a process of contamination similar to that for the Taylor Creek Rhyolite may help explain some of these situations.

Compositional gradients in large reservoirs of silicic magma as evidenced by ignimbrites versus Taylor Creek Rhyolite lava domes

USGS Publications Warehouse

Duffield, W.A.; Ruiz, J.

1992-01-01

The Taylor Creek Rhyolite of southwest New Mexico consists of 20 lava domes and flows that were emplaced during a period of a few thousand years or less in late Oligocene time. Including genetically associated pyroclastic deposits, which are about as voluminous as the lava domes and flows, the Taylor Creek Rhyolite represents roughly 100 km3 of magma erupted from vents distributed throughout an area of several hundred square kilometers. Major-element composition is metaluminous to weakly peraluminous high-silica rhyolite and is nearly constant throughout the lava field. The magma reservoir for the Taylor Creek Rhyolite was vertically zoned in trace elements, 87Sr/86Sr, and phenocryst abundance and size. Mean trace-element concentrations, ranges in concentrations, and element-pair correlations are similar to many subalkaline silicic ignimbrites. However, the polarity of the zonation was opposite that in reservoirs for ignimbrites, for most constituents. For example, compared to the Bishop Tuff, only 87Sr/86Sr and Sc increased upward in both reservoirs. Quite likely, a dominant but nonerupted volume of the magma reservoir for the Taylor Creek Rhyolite was zoned like that for the Bishop Tuff, whereas an erupted, few-hundred-meter-thick cap on the magma body was variably contaminated by roof rocks whose contribution to this part of the magma system moderated relatively extreme trace-element concentrations of uncontaminated Taylor Creek Rhyolite but did not change the sense of correlation for most element pairs. The contaminant probably was a Precambrian rock of broadly granitic composition and with very high 87Sr/86Sr. Although examples apparently are not yet reported in the literature, evidence for a similar thin contaminated cap on reservoirs for large-volume silicic ignimbrites may exist in the bottom few meters of ignimbrites or perhaps only in the pumice fallout that normally immediately precedes ignimbrite emplacement. 87Sr/86Sr in sanidine phenocrysts of the Taylor Creek Rhyolite is higher than that of their host whole rocks. Covariation of this isotope ratio with sanidine abundance and size indicates positive correlations for all three features with decreasing distance to the roof of the magma reservoir. The sanidine probably is more radiogenic than host whole rock because growing phenocrysts partly incorporated Sr from the first partial melt of roof rocks, which contained the highly radiogenic Sr of Precambrian biotite ?? hornblende, whereas diffusion was too slow for sanidine to incorporate much of the Sr from subsequently produced less radiogenic partial melt of roof rocks, before eruption quenched the magma system. Disequilibrium between feldspar phenocrysts and host groundmass is fairly common for ignimbrites, and a process of contamination similar to that for the Taylor Creek Rhyolite may help explain some of these situations. ?? 1992 Springer-Verlag.

Relativistic semiempirical-core-potential calculations in Ca+,Sr+ , and Ba+ ions on Lagrange meshes

NASA Astrophysics Data System (ADS)

Filippin, Livio; Schiffmann, Sacha; Dohet-Eraly, Jérémy; Baye, Daniel; Godefroid, Michel

2018-01-01

Relativistic atomic structure calculations are carried out in alkaline-earth-metal ions using a semiempirical-core-potential approach. The systems are partitioned into frozen-core electrons and an active valence electron. The core orbitals are defined by a Dirac-Hartree-Fock calculation using the grasp2k package. The valence electron is described by a Dirac-like Hamiltonian involving a core-polarization potential to simulate the core-valence electron correlation. The associated equation is solved with the Lagrange-mesh method, which is an approximate variational approach having the form of a mesh calculation because of the use of a Gauss quadrature to calculate matrix elements. Properties involving the low-lying metastable D 3 /2 ,5 /2 2 states of Ca+, Sr+, and Ba+ are studied, such as polarizabilities, one- and two-photon decay rates, and lifetimes. Good agreement is found with other theory and observation, which is promising for further applications in alkalilike systems.

Sr isotopic composition of Afar volcanics and its implication for mantle evolution

NASA Astrophysics Data System (ADS)

Barberi, F.; Civetta, L.; Varet, J.

1980-10-01

Investigations of Rb-Sr systematics of basalts from the Afar depression (Ethiopia) indicate the presence of a heterogeneous mantle source region. The Sr isotopic compositions of the basalts from the Afar axial and transverse ranges identify source regions which are enriched in LIL elements and radiogenic Sr (axial ranges) and others which are relatively depleted (transverse ranges). Sr isotopic composition of basalts from the Red Sea, Gulf of Aden and Gulf of Tadjoura, which range from 0.70300 to 0.70340 are also reported and compared with the more radiogenic Afar region, which is characterized by 87Sr/ 86Sr ranging from 0.70328 to 0.70410. Available geochemical and isotopic data suggest that a relation exists between magma composition and the advancement of the rifting process through progressive lithosphere attenuation leading to continental break-up. However, the petrogenetic process is not simple and probably implies a vertically zoned mantle beneath the Afar region. Sr isotopic evidence suggests that the vertically zoned mantle is more radiogenic and enriched in LIL elements in its upper part.

The spatial patterns of water management practices are reflected in the strontium isotope ratios of human hair

NASA Astrophysics Data System (ADS)

Tipple, B. J.; Valenzuela, L. O.; Ehleringer, J.

2012-12-01

Element concentrations and isotopes of human tissues are commonly used to understand how emissions and processes within urban ecosystems affect health. Thus, it is important to understand how these elements are incorporated and flow through the urban environment and are ultimately incorporated into human tissues. Here, we designed an experiment to identify the relative importance of strontium (Sr) sources (bedrock, dust, food, and water) to hair Sr isotope ratios (87Sr/86Sr). To understand the contribution of Sr to human hair, we collected hair from individuals living in Salt Lake City, Utah. In addition to sample location, we compiled information regarding age, sex, ethnicity, and dietary habits. We found a significant association between 87Sr/86Sr value of hair and collection location. There were no significant relationships between 87Sr/86Sr value of hair and age, ethnicity, or sex. We had not predicted a relationship between 87Sr/86Sr values and collection location, because of the close proximities of sites to one another (all within an 8-km radius). We found that tap water 87Sr/86Sr values across the Salt Lake Valley varied with water management practice and this variation corresponded to hair 87Sr/86Sr value. These data suggest an additional geographically controlled source of Sr may be an important contributor to the 87Sr/86Sr value of hair. These findings suggest that local water is an important source of Sr in human hair and that hair is a sensitive temporal carrier of this environmental information. These observations have important implications to future studies of humans with regard to urban ecology, human health, forensic sciences, and anthropology.

Optimization of thermoelectric performance of SrSi2-based alloys via the modification in band structure and phonon-point-defect scattering

PubMed Central

Kuo, Yung-Kang; Ramachandran, Balakrishnan; Lue, Chin-Shan

2014-01-01

Thermoelectric properties of alkaline-earth-metal disilicides are strongly dependent on their electronic band structure in the vicinity of the Fermi level. In particular, the strontium disilicide, SrSi2 with a narrow band gap of about few tens of meV is composed of non-toxic, naturally abundant elements, and its thermoelectric properties are very sensitive to the substitution/alloying with third elements. In this article, we summarize the thermoelectric performance of substituted and Sr-deficient/Sr-rich SrSi2 alloys to realize the high thermoelectric figure-of-merit (ZT) for practical applications in the electronic and thermoelectric aspects, and also to explore the alternative routes to further improve its ZT value. PMID:25505784

Decoupling of Mg-C and Sr-Nd-O isotopes traces the role of recycled carbon in magnesiocarbonatites from the Tarim Large Igneous Province

NASA Astrophysics Data System (ADS)

Cheng, Zhiguo; Zhang, Zhaochong; Hou, Tong; Santosh, M.; Chen, Lili; Ke, Shan; Xu, Lijuan

2017-04-01

The Tarim Large Igneous Province in NW China hosts numerous magmatic carbonatite dikes along its northern margin. The carbonatites are composed mainly of dolomite (90 vol.%) and minor calcite (5 vol.%), with apatite, barite, celestine, aegirine, monazite and bastnaesite as accessory minerals. The rocks correspond to magnesiocarbonatites with a compositional range of 13.73-19.59 wt.% MgO, and 20.03-30.11 wt.% CaO, along with 1.65-3.31 wt.% total Fe2O3, 0.02-2.39 wt.% SiO2 and other minor elements, such as P2O5, Na2O and K2O. These magnesiocarbonatites are characterized by extreme enrichment in incompatible elements with high total rare earth element (REE) contents of 372-36965 ppm. The strontium [(87Sr/86Sr)i = 0.70378-0.70386], neodymium [εNd(t) = +2.51 - +3.59] and oxygen (δ18OV-SMOW = 5.9‰-8.0‰) isotope values of these rocks are consistent with a mantle origin, whereas the magnesium (δ26Mg = -1.09‰ to -0.85‰) and carbon (δ13CV-PDB = -4.1‰ to -5.9‰) isotopes are decoupled from mantle values and reflect signature of recycled sedimentary carbonates. Global plate tectonic models predict that sedimentary carbonates in convergent margins are subducted to deep domains in the mantle, with phase transitions from calcite/dolomite to magnesite, and eventually to periclase/perovskite. The involvement of a mantle plume enhances the normal mantle geotherms and promotes decomposition reactions of magnesite. The decoupling of Mg-C and Sr-Nd-O isotopes in the mangesiocarbonatites provides insights on the origin of carbonatites, and also illustrates a case of interaction between mantle plume and subduction-related components.

Elements concentration analysis in groundwater from the North Serra Geral aquifer in Santa Helena-Brazil using SR-TXRF spectrometer.

PubMed

Justen, Gisele C; Espinoza-Quiñones, Fernando R; Módenes, Aparecido Nivaldo; Bergamasco, Rosangela

2012-01-01

In this work the analysis of elements concentration in groundwater was performed using the synchrotron radiation total-reflection X-ray fluorescence (SR-TXRF) technique. A set of nine tube-wells with serious risk of contamination was chosen to monitor the mean concentration of elements in groundwater from the North Serra Geral aquifer in Santa Helena, Brazil, during 1 year. Element concentrations were determined applying a SR-TXRF methodology. The accuracy of SR-TXRF technique was validated by analysis of a certified reference material. As the groundwater composition in the North Serra Geral aquifer showed heterogeneity in the spatial distribution of eight major elements, a hierarchical clustering to the data was performed. By a similarity in their compositions, two of the nine wells were grouped in a first cluster, while the other seven were grouped in a second cluster. Calcium was the major element in all wells, with higher Ca concentration in the second cluster than in the first cluster. However, concentrations of Ti, V, Cr in the first cluster are slightly higher than those in the second cluster. The findings of this study within a monitoring program of tube-wells could provide a useful assessment of controls over groundwater composition and support management at regional level.

Diagenetic changes in the elemental composition of unrecrystallized mollusk shells

USGS Publications Warehouse

Ragland, P.C.; Pilkey, O.H.; Blackwelder, B. W.

1979-01-01

The Mg, Sr, Mn, Fe, Na and K contents were determined for 230 apparently unrecrystallized mollusk shells (gastropods and bivalves) ranging in age from late Cretaceous to Holocene. Consistent differences between the Holocene and fossil shells with respect to concentrations of all these elements are attributed to postburial diagenetic changes. Fossil-Holocene shell comparisons are made on the intergeneric level, a more severe test of compositional differences than was previous work involved with few species. The observed differences re-emphasize the need for extreme caution in the use of the many geochemical tools which assume that no compositional changes have taken place prior to recrystallization of calcareous materials. ?? 1979.

Multi-Scale Stochastic Resonance Spectrogram for fault diagnosis of rolling element bearings

NASA Astrophysics Data System (ADS)

He, Qingbo; Wu, Enhao; Pan, Yuanyuan

2018-04-01

It is not easy to identify incipient defect of a rolling element bearing by analyzing the vibration data because of the disturbance of background noise. The weak and unrecognizable transient fault signal of a mechanical system can be enhanced by the stochastic resonance (SR) technique that utilizes the noise in the system. However, it is challenging for the SR technique to identify sensitive fault information in non-stationary signals. This paper proposes a new method called multi-scale SR spectrogram (MSSRS) for bearing defect diagnosis. The new method considers the non-stationary property of the defective bearing vibration signals, and treats every scale of the time-frequency distribution (TFD) as a modulation system. Then the SR technique is utilized on each modulation system according to each frequencies in the TFD. The SR results are sensitive to the defect information because the energy of transient vibration is distributed in a limited frequency band in the TFD. Collecting the spectra of the SR outputs at all frequency scales then generates the MSSRS. The proposed MSSRS is able to well deal with the non-stationary transient signal, and can highlight the defect-induced frequency component corresponding to the impulse information. Experimental results with practical defective bearing vibration data have shown that the proposed method outperforms the former SR methods and exhibits a good application prospect in rolling element bearing fault diagnosis.

Caesium and strontium accumulation in shoots of Arabidopsis thaliana: genetic and physiological aspects

PubMed Central

Kanter, Ulrike; Hauser, Andreas; Michalke, Bernhard; Dräxl, Stephan; Schäffner, Anton R.

2010-01-01

Due to the physico-chemical similarities of caesium (Cs+) to potassium (K+) on the one hand and strontium (Sr2+) to calcium (Ca2+) on the other hand, both elements can easily be taken up by plants and thus enter the food chain. This could be detrimental when radionuclides such as 137Cs and 90Sr are involved. In this study, both genetic and physiological aspects of Cs+ and Sr2+ accumulation in Arabidopsis thaliana were investigated using 86 Arabidopsis accessions and a segregating F2 population of the low Cs+ accumulating Sq-1 (Ascot, UK) crossed with the high uptaking Sorbo (Khurmatov, Tajikistan). Hydroponically grown plants were exposed to subtoxic levels of Cs+ and Sr2+ using radioactive isotopes as tracers. In the natural accessions shoot concentration of Cs+ as well as Sr2+ varied about 2-fold, whereas its heritability ranged for both ions between 0.60 and 0.73. Shoot accumulation of Cs+ and Sr2+ could be compromised by increasing concentrations of their essential analogues K+ and Ca2+, respectively, causing a reduction of up to 80%. In the case of the segregating F2/F3 population Sq-1×Sorbo, this study identified several QTL for the trait Cs+ and Sr2+ accumulation, with main QTL on chromosomes 1 and 5. According to the correlation and discrimination surveys combined with QTL-analysis Cs+ and Sr2+ uptake seemed to be mediated mostly via non-selective cation channels. A polymorphism, affecting amino acids close to the K+-pore of one candidate, CYCLIC-NUCLEOTIDE-GATED CHANNEL 1 (CNGC1), was identified in Sorbo and associated with high Cs+ concentrating accessions. PMID:20624763

Compositions of HIMU, EM1, and EM2 from Global Trends between Radiogenic Isotopes and Major Elements in Ocean Island Basalts

NASA Astrophysics Data System (ADS)

Jackson, M. G.; Dasgupta, R.

2008-12-01

Sr and Pb isotopes exhibit global trends with the concentrations of major elements (SiO2, TiO2, FeO, Al2O3 and K2O) and major elements ratios (CaO/Al2O3 and K2O/TiO2) in the shield-stage lavas from 18 oceanic hotspots (including Hawaii, Iceland, Galapagos, Cook-Australs, St. Helena, Cape Verde, Cameroon, Canary, Madeira, Comoros, Azores, Samoa, Society, Marquesas, Mascarene, Kerguelen, Pitcairn, and Selvagen). Based on the relationships between major elements and isotopes in ocean island basalts (OIBs), we find that the lavas derived from the mantle end members, HIMU (or high 'ì' = 238U/204Pb), EM1 (enriched mantle 1), EM2 (enriched mantle 2), and DMM (depleted MORB [mid-ocean ridge basalt] mantle) exhibit distinct major element characteristics: When compared to oceanic hotspots globally, the hotspots with a HIMU (radiogenic Pb-isotopes and low 87Sr/86Sr) component, such as St. Helena and Cook-Australs, exhibit high CaO/Al2O3, FeOT, and TiO2 and low SiO2 and Al2O3. EM1 (enriched mantle 1; intermediate 87Sr/86Sr and low 206Pb/204Pb; sampled by hotspots like Pitcairn and Kerguelen) and EM2 (enriched mantle 2; high 87Sr/86Sr and intermediate 206Pb/204Pb; sampled by hotspots like Samoa and Societies) exhibit higher K2O concentrations and K2O/TiO2 weight ratios than HIMU lavas. EM1 lavas exhibit the lowest CaO/Al2O3 in the OIB dataset, and this sets EM1 apart from EM2. A plot of CaO/Al2O3 vs K2O/TiO2 perfectly resolves the four mantle end member lavas. Melting processes (pressure, temperature and degree of melting) fail to provide an explanation for the full spectrum of major element concentrations in OIBs. Such processes also fail to explain the correlations between major elements and radiogenic isotopes. Instead, a long, time integrated history of various parent- daughter elements appears to be coupled to major element and/or volatile heterogeneity in the mantle source. End member lava compositions are compared with experimental partial melt compositions to place constraints on the lithological characteristics of the mantle end members.

Compositions of HIMU, EM1, and EM2 from global trends between radiogenic isotopes and major elements in ocean island basalts

NASA Astrophysics Data System (ADS)

Jackson, Matthew G.; Dasgupta, Rajdeep

2008-11-01

Sr and Pb isotopes exhibit global trends with the concentrations of major elements (SiO 2, TiO 2, FeO, Al 2O 3 and K 2O) and major elements ratios (CaO/Al 2O 3 and K 2O/TiO 2) in the shield-stage lavas from 18 oceanic hotspots (including Hawaii, Iceland, Galapagos, Cook-Australs, St. Helena, Cape Verde, Cameroon, Canary, Madeira, Comoros, Azores, Samoa, Society, Marquesas, Mascarene, Kerguelen, Pitcairn, and Selvagen). Based on the relationships between major elements and isotopes in ocean island basalts (OIBs), we find that the lavas derived from the mantle end members, HIMU (or high 'μ' = 238U/ 204Pb), EM1 (enriched mantle 1), EM2 (enriched mantle 2), and DMM (depleted MORB [mid-ocean ridge basalt] mantle) exhibit distinct major element characteristics: When compared to oceanic hotspots globally, the hotspots with a HIMU (radiogenic Pb-isotopes and low 87Sr/ 86Sr) component, such as St. Helena and Cook-Australs, exhibit high CaO/Al 2O 3, FeO T, and TiO 2 and low SiO 2 and Al 2O 3. EM1 (enriched mantle 1; intermediate 87Sr/ 86Sr and low 206Pb/ 204Pb; sampled by hotspots like Pitcairn and Kerguelen) and EM2 (enriched mantle 2; high 87Sr/ 86Sr and intermediate 206Pb/ 204Pb; sampled by hotspots like Samoa and Societies) exhibit higher K 2O concentrations and K 2O/TiO 2 weight ratios than HIMU lavas. EM1 lavas exhibit the lowest CaO/Al 2O 3 in the OIB dataset, and this sets EM1 apart from EM2. A plot of CaO/Al 2O 3 vs K 2O/TiO 2 perfectly resolves the four mantle end member lavas. Melting processes (pressure, temperature and degree of melting) fail to provide an explanation for the full spectrum of major element concentrations in OIBs. Such processes also fail to explain the correlations between major elements and radiogenic isotopes. Instead, a long, time integrated history of various parent-daughter elements appears to be coupled to major element and/or volatile heterogeneity in the mantle source. End member lava compositions are compared with experimental partial melt compositions to place constraints on the lithological characteristics of the mantle end members.

Niacin improves renal lipid metabolism and slows progression in chronic kidney disease.

PubMed

Cho, Kyu-hyang; Kim, Hyun-ju; Kamanna, Vaijinath S; Vaziri, Nosratola D

2010-01-01

Mounting evidence points to lipid accumulation in the diseased kidney and its contribution to progression of nephropathy. We recently found heavy lipid accumulation and marked dysregulation of lipid metabolism in the remnant kidneys of rats with chronic renal failure (CRF). Present study sought to determine efficacy of niacin supplementation on renal tissue lipid metabolism in CRF. Kidney function, lipid content, and expression of molecules involved in cholesterol and fatty acid metabolism were determined in untreated CRF (5/6 nephrectomized), niacin-treated CRF (50 mg/kg/day in drinking water for 12 weeks) and control rats. CRF resulted in hypertension, proteinuria, renal tissue lipid accumulation, up-regulation of scavenger receptor A1 (SR-A1), acyl-CoA cholesterol acyltransferase-1 (ACAT1), carbohydrate-responsive element binding protein (ChREBP), fatty acid synthase (FAS), acyl-CoA carboxylase (ACC), liver X receptor (LXR), ATP binding cassette (ABC) A-1, ABCG-1, and SR-B1 and down-regulation of sterol responsive element binding protein-1 (SREBP-1), SREBP-2, HMG-CoA reductase, PPAR-alpha, fatty acid binding protein (L-FABP), and CPT1A. Niacin therapy attenuated hypertension, proteinuria, and tubulo-interstitial injury, reduced renal tissue lipids, CD36, ChREBP, LXR, ABCA-1, ABCG-1, and SR-B1 abundance and raised PPAR-alpha and L-FABP. Niacin administration improves renal tissue lipid metabolism and renal function and structure in experimental CRF.

Mussel Shell Evaluation as Bioindicator For Heavy Metals

NASA Astrophysics Data System (ADS)

Andrello, Avacir Casanova; Lopes, Fábio; Galvão, Tiago Dutra

2010-05-01

Recently, in Brazil, it has appeared a new and unusual "plague" in lazer and commercial fishing. It is caused by the parasitic larval phase of certain native bivalve mollusks of fresh water known as "Naiades" and its involves the presence of big bivalve of fresh water, mainly Anodontites trapesialis, in the tanks and dams of the fish creation. These bivalve mollusks belong to the Unionoida Order, Mycetopodidae Family. The objective of the present work was to analyze the shells of these mollusks to verify the possibility of use as bioindicators for heavy metals in freshwater. The mollusks shells were collected in a commercial fishing at Londrina-PR. A qualitative analysis was made to determine the chemical composition of the shells and verify a possible correlation with existent heavy metals in the aquatic environment. In the inner part of the shells were identified the elements Ca, P, Fe, Mn and Sr and in the outer part were identified Ca, P, Fe, Mn, Sr and Cu. The Ca ratio of the outer part by inner part of the analyzed shells is around of 1, as expected, because Ca is the main compound of mollusks shells. The ratio of P, Fe, Mn, and Sr to the Ca were constant in all analyzed shells, being close to 0.015. The ratio Cu/Ca varied among the shells, showing that this mollusk is sensitive to concentration of this element in the aquatic environment.

The sources and time-integrated evolution of diamond-forming fluids - Trace elements and isotopic evidence

NASA Astrophysics Data System (ADS)

Klein-BenDavid, Ofra; Pearson, D. Graham; Nowell, Geoff M.; Ottley, Chris; McNeill, John C. R.; Logvinova, Alla; Sobolev, Nikolay V.

2014-01-01

Sub-micrometer inclusions in fibrous diamond growth zones carry high-density fluids (HDF) from which the host diamonds have precipitated. The chemistry of these fluids is our best opportunity of characterizing the diamond-forming environment. The major and trace element patterns of diamond-forming fluids vary widely. Such elemental signatures can be easily modified by a variety of mantle processes whereas radiogenic isotopes give a clear fingerprint of the time-integrated evolution of the fluid source region. Thus, the combination of elemental and isotope data is a powerful tool in constraining the origin of fluids from which diamonds precipitate. Here we present combined trace element composition (34 diamonds) and Sr isotopic data (23 diamonds) for fluid-rich diamonds from six worldwide locations. The Nd and Pb isotopic composition of two of the diamonds were also obtained. Several of the samples were analyzed in at least 2 locations to investigate variations in the fluid during diamond growth. The data was acquired using an off-line laser sampling technique followed by solution ICPMS and TIMS analysis. The Sr isotopic compositions of diamond fluids from the different suites range between convecting mantle values for Udachnaya (87Sr/86Sr363 = 0.70300 ± 16 to 0.70361 ± 4), to highly enriched values, up to 87Sr/86Sr = 0.72330 ± 3, for a diamond from Congo. No isochronous relationships were observed in any of the suites. The lowest Nd isotopic composition recorded so far in a diamond is from Congo (εNd71 = -40.4), which also contains the most radiogenic Sr isotopic composition. In contrast, a less enriched but still rather unradiogenic Nd isotope composition (εNd540 = -11) was obtained for a diamond from Snap Lake, which has moderately radiogenic Sr isotopic enrichment (87Sr/86Sr540 = 0.70821 ± 1). The Pb isotopic system measured in one diamond indicates a complex evolution for the fluid source, with extreme 207Pb/204Pb ratio (15.810 ± 3) and moderate, kimberlite-like 206Pb/204Pb and 208Pb/204Pb ratios. A multi-stage evolution of the diamond-forming fluids source can be constrained from our new isotopic data, indicating an Achaean enrichment event resulting in elevated U/Pb, Rb/Sr ratios and enrichment in LREEs. This source underwent a more recent fractionation, in the last 500 Myr that may have been related to the diamond-forming event. There is a strong correspondence between fluids with relatively unradiogenic Sr isotopes and relatively low (La, Nd, Sm)/(Nb, Zr) and (Ba, Th)/(Nb) ratios. Sr isotopic enrichment is accompanied by an increase in these ratios. The least trace element enriched and most isotopically depleted fluids are from the high-Mg carbonatitic suite. Thus, HDFs could be derived from asthenospheric mantle as low degree melts that interact to varying degrees with an ancient, metasomatized, rutile- and phlogopite bearing, sub continental lithosphere mantle. The internal heterogeneity in the Sr isotopic ratios within a single diamond suite and even within single diamonds may indicate fluid-mixing processes. Such mixing may occur during migration through preferred mantle veins and may be affected by the small-scale geochemical variability within them.

Spatial distribution of the trace elements zinc, strontium and lead in human bone tissue.

PubMed

Pemmer, B; Roschger, A; Wastl, A; Hofstaetter, J G; Wobrauschek, P; Simon, R; Thaler, H W; Roschger, P; Klaushofer, K; Streli, C

2013-11-01

Trace elements are chemical elements in minute quantities, which are known to accumulate in the bone. Cortical and trabecular bones consist of bone structural units (BSUs) such as osteons and bone packets of different mineral content and are separated by cement lines. Previous studies investigating trace elements in bone lacked resolution and therefore very little is known about the local concentration of zinc (Zn), strontium (Sr) and lead (Pb) in BSUs of human bone. We used synchrotron radiation induced micro X-ray fluorescence analysis (SR μ-XRF) in combination with quantitative backscattered electron imaging (qBEI) to determine the distribution and accumulation of Zn, Sr, and Pb in human bone tissue. Fourteen human bone samples (10 femoral necks and 4 femoral heads) from individuals with osteoporotic femoral neck fractures as well as from healthy individuals were analyzed. Fluorescence intensity maps were matched with BE images and correlated with calcium (Ca) content. We found that Zn and Pb had significantly increased levels in the cement lines of all samples compared to the surrounding mineralized bone matrix. Pb and Sr levels were found to be correlated with the degree of mineralization. Interestingly, Zn intensities had no correlation with Ca levels. We have shown for the first time that there is a differential accumulation of the trace elements Zn, Pb and Sr in BSUs of human bone indicating different mechanisms of accumulation. © 2013. Published by Elsevier Inc. All rights reserved.

Boron and strontium isotope ratios and major/trace elements concentrations in tea leaves at four major tea growing gardens in Taiwan.

PubMed

Chang, Cheng-Ta; You, Chen-Feng; Aggarwal, Suresh Kumar; Chung, Chuan-Hsiung; Chao, Hung-Chun; Liu, Hou-Chun

2016-06-01

Isotopic compositions of B and Sr in rocks and sediments can be used as tracers for plant provincial sources. This study aims to test whether tea leaf origin can be discriminated using (10)B/(11)B and Sr isotopic composition data, along with concentrations of major/trace elements, in tea specimens collected from major plantation gardens in Taiwan. The tea leaves were digested by microwave and analyzed by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). The data showed significant variations in (87)Sr/(86)Sr ratios (from 0.70482 to 0.71462), which reflect changes in soil, groundwater or irrigation conditions. The most radiogenic tea leaves were found at the Taitung garden and the least radiogenic ones were from the Hualien garden. The δ (11)B was found to change appreciably (δ (11)B = 0.38-23.73 ‰) which could be due to fertilizers. The maximum δ (11)B was also observed in tea samples from the Hualien garden. Principal component analysis combining (87)Sr/(86)Sr, δ (11)B and major/trace elements results successfully discriminated different sources of major tea gardens in Taiwan, except the Hualien gardens, and this may be due to rather complicated local geological settings.

Incorporating Cs and Sr into blast furnace slag inorganic polymers and their effect on matrix properties

NASA Astrophysics Data System (ADS)

Vandevenne, Niels; Iacobescu, Remus Ion; Pontikes, Yiannis; Carleer, Robert; Thijssen, Elsy; Gijbels, Katrijn; Schreurs, Sonja; Schroeyers, Wouter

2018-05-01

Minimizing harmful effects to the environment in waste-management practices requires continuous innovation. This is especially important in the field of radioactive waste management. Alternatives to the commonly used ordinary Portland cement matrices are being increasingly studied for improved immobilisation purposes. The development of inorganic polymers (IP) from industrial residues has been successfully studied for the immobilisation of caesium (Cs+) and strontium (Sr2+). However, knowledge of the effect of these introduced elements on the IP-matrix is scarce, especially considering that studied effects are dependent on the IP-precursor characteristics and the form in which the Cs+ and Sr2+ are introduced. In this study, IPs containing varying amounts of CsNO3 and Sr(NO3)2 were developed to study the effect of the introduced elements on the IP-characteristics. IP-samples were developed from ground granulated blast furnace slag (GGBFS) and 6 M NaOH activating solution. Cs+ and Sr2+ were added to account for 0.5, 1 and 2 wt% of the total IP-mass. Throughout the entire study, Cs+-addition showed no significant effects on the studied parameters. Calorimetric results showed that Sr2+ severely affects reaction kinetics, consuming hydroxide ions necessary for the alkali activation reaction. Sr2+-addition also caused a severe decrease in compressive strength, increased calcium leaching, and decreased sodium and hydroxide leaching. Micro-chemical analyses showed that Cs+ is almost fully incorporated in the formed IP-matrix, while Sr2+ mainly precipitates as Sr(OH)2 in concentrated regions throughout the IP-structure. The findings presented in this paper give insights on the effect of contaminant elements on the immobilising matrix.

Archean crust-mantle geochemical differentiation

NASA Astrophysics Data System (ADS)

Tilton, G. R.

Isotope measurements on carbonatite complexes and komatiites can provide information on the geochemical character and geochemical evolution of the mantle, including the sub-continental mantle. Measurements on young samples establish the validity of the method. These are based on Sr, Nd and Pb data from the Tertiary-Mesozoic Gorgona komatiite and Sr and Pb data from the Cretaceous Oka carbonatite complex. In both cases the data describe a LIL element-depleted source similar to that observed presently in MORB. Carbonatite data have been used to study the mantle beneath the Superior Province of the Canadian Shield one billion years (1 AE) ago. The framework for this investigation was established by Bell et al., who showed that large areas of the province appear to be underlain by LIL element-depleted mantle (Sr-85/Sr-86=0.7028) at 1 AE ago. Additionally Bell et al. found four complexes to have higher initial Sr ratios (Sr-87/Sr-86=0.7038), which they correlated with less depleted (bulk earth?) mantle sources, or possibly crustal contamination. Pb isotope relationships in four of the complexes have been studied by Bell et al.

Archean crust-mantle geochemical differentiation

NASA Technical Reports Server (NTRS)

Tilton, G. R.

1983-01-01

Isotope measurements on carbonatite complexes and komatiites can provide information on the geochemical character and geochemical evolution of the mantle, including the sub-continental mantle. Measurements on young samples establish the validity of the method. These are based on Sr, Nd and Pb data from the Tertiary-Mesozoic Gorgona komatiite and Sr and Pb data from the Cretaceous Oka carbonatite complex. In both cases the data describe a LIL element-depleted source similar to that observed presently in MORB. Carbonatite data have been used to study the mantle beneath the Superior Province of the Canadian Shield one billion years (1 AE) ago. The framework for this investigation was established by Bell et al., who showed that large areas of the province appear to be underlain by LIL element-depleted mantle (Sr-85/Sr-86=0.7028) at 1 AE ago. Additionally Bell et al. found four complexes to have higher initial Sr ratios (Sr-87/Sr-86=0.7038), which they correlated with less depleted (bulk earth?) mantle sources, or possibly crustal contamination. Pb isotope relationships in four of the complexes have been studied by Bell et al.

Influence of rare earth doping on thermoelectric properties of SrTiO3 ceramics

NASA Astrophysics Data System (ADS)

Liu, J.; Wang, C. L.; Li, Y.; Su, W. B.; Zhu, Y. H.; Li, J. C.; Mei, L. M.

2013-12-01

Thermoelectric properties of SrTiO3 ceramics, doped with different rare earth elements, were investigated in this work. It's found that the ionic radius of doping elements plays an important role on thermoelectric properties: SrTiO3 ceramics doped with large rare earth ions (such as La, Nd, and Sm) exhibit large power factors, and those doped with small ions (such as Gd, Dy, Er, and Y) exhibit low thermal conductivities. Therefore, a simple approach for enhancing the thermoelectric performance of SrTiO3 ceramics is proposed: mainly doped with large ions to obtain a large power factor and, simultaneously, slightly co-doped with small ions to obtain a low thermal conductivity. Based on this rule, Sr0.8La0.18Yb0.02TiO3 ceramics were prepared, whose ZT value at 1 023 K reaches 0.31, increasing by a factor of 19% compared with the single-doped counterpart Sr0.8La0.2TiO3 (ZT = 0.26).

Geochemistry of the Serifos calc-alkaline granodiorite pluton, Greece: constraining the crust and mantle contributions to I-type granitoids

NASA Astrophysics Data System (ADS)

Stouraiti, C.; Baziotis, I.; Asimow, P. D.; Downes, H.

2017-11-01

The Late Miocene (11.6-9.5 Ma) granitoid intrusion on the island of Serifos (Western Cyclades, Aegean Sea) is composed of syn- to post-tectonic granodiorite with quartz monzodiorite enclaves, cut by dacitic and aplitic dikes. The granitoid, a typical I-type metaluminous calcic amphibole-bearing calc-alkaline pluton, intruded the Cycladic Blueschists during thinning of the Aegean plate. Combining field, textural, geochemical and new Sr-Nd-O isotope data presented in this paper, we postulate that the Serifos intrusion is a single-zoned pluton. The central facies has initial 87Sr/86Sr = 0.70906 to 0.7106, ɛNd(t) = - 5.9 to - 7.5 and δ18Οqtz = + 10 to + 10.6‰, whereas the marginal zone (or border facies) has higher initial 87Sr/86Sr = 0.711 to 0.7112, lower ɛ Nd(t) = - 7.3 to - 8.3, and higher δ18Οqtz = + 10.6 to + 11.9‰. The small range in initial Sr and Nd isotopic values throughout the pluton is paired with a remarkable uniformity in trace element patterns, despite a large range in silica contents (58.8 to 72 wt% SiO2). Assimilation of a crustally derived partial melt into the mafic parental magma would progressively add incompatible trace elements and SiO2 to the evolving mafic starting liquid, but the opposite trend, of trace element depletion during magma evolution, is observed in the Serifos granodiorites. Thermodynamic modeling of whole-rock compositions during simple fractional crystallization (FC) or assimilation-fractional crystallization (AFC) processes of major rock-forming minerals—at a variety of pressure, oxidation state, and water activity conditions—fails to reproduce simultaneously the major element and trace element variations among the Serifos granitoids, implying a critical role for minor phases in controlling trace element fractionation. Both saturation of accessory phases such as allanite and titanite (at SiO2 ≥ 71 wt%)(to satisfy trace element constraints) and assimilation of partial melts from a metasedimentary component (to match isotopic data) must have accompanied fractional crystallization of the major phases.

Age and character of basaltic rocks of the Yucca Mountain region, southern Nevada

USGS Publications Warehouse

Fleck, R.J.; Turrin, B.D.; Sawyer, D.A.; Warren, R.G.; Champion, D.E.; Hudson, M.R.; Minor, S.A.

1996-01-01

Volcanism in the Yucca Mountain region of southern Nevada in the last 5 m.y. is restricted to moderate-to-small volumes of subalkaline basaltic magmas, produced during at least 6 intervals, and spanning an age range from 4.6 Ma to about 125 ka. Where paleomagnetic evidence is available, the period of volcanism at individual eruptive centers apparently was geologically short-lived, even where multiple eruptions involved different magma types. K-Ar studies are consistent with most other geochronologic information, such as the minimum ages of exposure-dating techniques, and show no evidence of renewed volcanism after a significant quiescence at any of the centers in the Yucca Mountain region. A volcanic recurrence interval of 860 ?? 350 kyr is computed from a large K-Ar data set and an evaluation of their uncertainties. Monte Carlo error propagations demonstrate the validity of uncertainties obtained for weighted-mean ages when modified using the goodness of fit parameter, MSWD. Elevated 87Sr/86Sr initial ratios (Sri) in the basalts, nearly constant at 0.707, combined with low SiO2 and Rb/Sr ratios indicate a subcontinental, lithospheric mantle source, previously enriched in radiogenic Sr and depleted in Rb. Beginning with eruptions of the most voluminous eruptive center, the newly dated Pliocene Thirsty Mountain volcano, basaltic magmas have decreased in eruptive volume, plagioclase-phenocryst content, various trace element ratios, and TiO2, while increasing in light rare earth elements, U, Th, P2O5, and light REE/heavy REE ratios. These time-correlated changes are consistent with either increasing depths of melting or a decreasing thermal gradient in the Yucca Mountain region during the last 5 m.y.

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

Yang, Qingcheng, E-mail: qiy9@pitt.edu; To, Albert C., E-mail: albertto@pitt.edu

Surface effects have been observed to contribute significantly to the mechanical response of nanoscale structures. The newly proposed energy-based coarse-grained atomistic method Multiresolution Molecular Mechanics (MMM) (Yang, To (2015), ) is applied to capture surface effect for nanosized structures by designing a surface summation rule SR{sup S} within the framework of MMM. Combined with previously proposed bulk summation rule SR{sup B}, the MMM summation rule SR{sup MMM} is completed. SR{sup S} and SR{sup B} are consistently formed within SR{sup MMM} for general finite element shape functions. Analogous to quadrature rules in finite element method (FEM), the key idea to themore » good performance of SR{sup MMM} lies in that the order or distribution of energy for coarse-grained atomistic model is mathematically derived such that the number, position and weight of quadrature-type (sampling) atoms can be determined. Mathematically, the derived energy distribution of surface area is different from that of bulk region. Physically, the difference is due to the fact that surface atoms lack neighboring bonding. As such, SR{sup S} and SR{sup B} are employed for surface and bulk domains, respectively. Two- and three-dimensional numerical examples using the respective 4-node bilinear quadrilateral, 8-node quadratic quadrilateral and 8-node hexahedral meshes are employed to verify and validate the proposed approach. It is shown that MMM with SR{sup MMM} accurately captures corner, edge and surface effects with less 0.3% degrees of freedom of the original atomistic system, compared against full atomistic simulation. The effectiveness of SR{sup MMM} with respect to high order element is also demonstrated by employing the 8-node quadratic quadrilateral to solve a beam bending problem considering surface effect. In addition, the introduced sampling error with SR{sup MMM} that is analogous to numerical integration error with quadrature rule in FEM is very small. - Highlights: • Surface effect captured by Multiresolution Molecular Mechanics (MMM) is presented. • A novel surface summation rule within the framework of MMM is proposed. • Surface, corner and edges effects are accuterly captured in two and three dimension. • MMM with less 0.3% degrees of freedom of atomistics reproduces atomistic results.« 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.

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.

Characteristics and source identification of dissolved trace elements in the Jinshui River of the South Qinling Mts., China.

PubMed

Bu, Hongmei; Wang, Weibo; Song, Xianfang; Zhang, Quanfa

2015-09-01

Dissolved trace elements and physiochemical parameters were analyzed to investigate their physicochemical characteristics and identify their sources at 12 sampling sites of the Jinshui River in the South Qinling Mts., China from October 2006 to November 2008. The two-factor ANOVA indicated significant temporal variations of the dissolved Cu, Fe, Sr, Si, and V (p < 0.001 or p < 0.05). With the exception of Sr (p < 0.001), no significant spatial variations were found. Distributions and concentrations of the dissolved trace elements displayed that dissolved Cu, Fe, Sr, Si, V, and Cr were originated from chemical weathering and leaching from the soil and bedrock. Dissolved Cu, Fe, Sr, As, and Si were also from anthropogenic inputs (farming and domestic effluents). Correlation and regression analysis showed that the chemical and physical processes of dissolved Cu was influenced by water temperature and dissolved oxygen (DO) to some degree. Dissolved Fe and Sr were affected by colloid destabilization or sedimentary inputs. Concentrations of dissolved Si were slightly controlled by biological uptake. Principal component analysis confirmed that Fe, Sr, and V resulted from domestic effluents, agricultural runoff, and confluence, whereas As, Cu, and Si were from agricultural activities, and Cr and Zn through natural processes. The research results provide a reference for ecological restoration and protection of the river environment in the Qinling Mts., China.

Mapping Metal Elements of Shuangbai Dinosaur Fossil by Synchrotron X-ray Fluorescence Microprobe

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

Wang, Y.; Qun, Y; Ablett, J

The metal elements mapping of Shuangbai dinosaur fossil, was obtained by synchrotron x-ray fluorescence (SXRF). Eight elements, Ca, Mn, Fe, Cu, Zn, As, Y and Sr were determined. Elements As and Y were detected for the first time in the dinosaur fossil. The data indicated that metal elements are asymmetrical on fossil section. This is different from common minerals. Mapping metals showed that metal element As is few. The dinosaur most likely belongs to natural death. This is different from Zigong dinosaurs which were found dead from poisoning. This method has been used to find that metals Fe and Mnmore » are accrete, and the same is true for Sr and Y. This study indicated that colloid granule Fe and Mn, as well as Sr and Y had opposite electric charges in lithification process of fossils. By this analysis, compound forms can be ascertained. Synchrotron light source x-ray fluorescence is a complementary method that shows mapping of metal elements at the dinosaur fossil, and is rapid, exact and intuitionist. This study shows that dinosaur fossil mineral imaging has a potential in reconstructing the paleoenvironment and ancient geology.« less

Melting and Vaporization of the 1223 Phase in the System (Tl-Pb-Ba-Sr-Ca-Cu-O)

PubMed Central

Cook, L. P.; Wong-Ng, W.; Paranthaman, P.

1996-01-01

The melting and vaporization of the 1223 [(Tl,Pb):(Ba,Sr):Ca:Cu] oxide phase in the system (Tl-Pb-Ba-Sr-Ca-Cu-O) have been investigated using a combination of dynamic methods (differential thermal analysis, thermogravimetry, effusion) and post-quenching characterization techniques (powder x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectrometry). Vaporization rates, thermal events, and melt compositions were followed as a function of thallia loss from a 1223 stoichiometry. Melting and vaporization equilibria of the 1223 phase are complex, with as many as seven phases participating simultaneously. At a total pressure of 0.1 MPa the 1223 phase was found to melt completely at (980 ± 5) °C in oxygen, at a thallia partial pressure (pTl2O) of (4.6 ± 0.5) kPa, where the quoted uncertainties are standard uncertainties, i.e., 1 estimated standard deviation. The melting reaction involves five other solids and a liquid, nominally as follows: 1223→1212+(Ca,Sr)2CuO3+(Sr,Ca)CuO2+BaPbO3+(Ca,Sr)O+Liquid Stoichiometries of the participating phases have been determined from microchemical analysis, and substantial elemental substitution on the 1212 and 1223 crystallographic sites is indicated. The 1223 phase occurs in equilibrium with liquids from its melting point down to at least 935 °C. The composition of the lowest melting liquid detected for the bulk compositions of this study has been measured using microchemical analysis. Applications to the processing of superconducting wires and tapes are discussed. PMID:27805086

Zircon U-Pb ages and geochemistry of migmatites and granites in the Foping dome: Evidence for Late Triassic crustal evolution in South Qinling, China

NASA Astrophysics Data System (ADS)

Zhang, He; Li, Shuang-Qing; Fang, Bo-Wen; He, Jian-Feng; Xue, Ying-Yu; Siebel, Wolfgang; Chen, Fukun

2018-01-01

Migmatites provide a record of melt formation and crustal rheology. In this study we present zircon U-Pb ages and geochemical composition of migmatites from the Foping dome and granites from the Wulong pluton. U-Pb results from migmatite zircons indicate two episodes of partial melting. Rim domains from a leucosome in the Longcaoping area yield an age of ca. 209 Ma. Migmatites collected from the Foping dome yield U-Pb zircon ages of 2910 to 190 Ma, suggesting the involvement of meta-sedimentary source components. Rim domains of the zircons with low Th/U ratios (< 0.1) give ages of 225-190 Ma and the youngest age domains (ca. 195 Ma) are characterized by low contents of heavy rare earth elements, which is related to crystallization of garnet. Magmatic rocks from the Wulong pluton can be subdivided into high Sr/Y and low Sr/Y granites. U-Pb zircon ages vary from 219 to 214 Ma for the high Sr/Y granites and from 214 to 192 Ma for the low Sr/Y granites. High Sr/Y granites have higher Na2O and Sr contents than the low Sr/Y granites. They also lack negative Eu anomalies and are depleted in HREE compared to the low Sr/Y granites. Initial 87Sr/86Sr ratios and εNd values of all the samples roughly overlap with those of Neoproterozoic basement rocks exposed in South Qinling. Including previous studies, we propose that the high and low Sr/Y granites formed by melting of thickened and normal crust, respectively. Close temporal-spatial relationship of the high and low Sr/Y granites with the two-stage migmatization events implies variation of crustal thickness and thermal overprints of the orogenic crust in post-collisional collapse. Following the collision of South Qinling and the Yangtze block prior to 219 Ma, partial melting of the deep crust occurred. The melts migrated upwards to form the high Sr/Y granites. This process occurred rapidly and caused collapse of the thickened crust and carried heat upwards, leading to further partial melting within the shallower crust and formation of the low Sr/Y granites.

Constraints on Ca/Sr as a Proxy for Calcium in Forest Ecosystems

NASA Astrophysics Data System (ADS)

Hoff, C. J.; Hobbie, E. A.; Hallett, R.; Colpaert, J.; Bryce, J. G.

2004-05-01

Calcium is a key plant nutrient and important base cation in ecosystems. Our current efforts to quantify Ca cycling in ecosystems rely on indirect proxies, e.g., Ca/Sr or Sr isotopic systems (1). An important assumption in these applications is that the elemental ratio of calcium to strontium faithfully represents calcium cycling and that little fractionation occurs through biogeochemical and physiological processes. However, several researchers have reported variations in Ca/Sr, e.g. among different tree tissues (2) and during weathering processes (3), raising doubts about the suitability of the proxy. To address the question of reliability, we measured Ca/Sr values in a culture study in which Scots pines were grown at low or high nutrient supply rates (3% per day or 5% per day). Because mycorrhizal fungi are intimately involved in plant nutrient supply, plants were also grown either uncolonized or colonized with one of two different species of mycorrhizal fungi (Suillus luteus and Thelephora terrestris). Our preliminary results indicate that Ca/Sr values differ between high and low nutrient treatments, root and foliage, and mycorrhizal treatments. In individual seedlings, roots have lower Ca/Sr than foliage by absolute factors of 2-5. The magnitude of the effect is apparently determined by a combination of environmental factors including both the nutrient and mycorrhizal treatments. These results indicate that Ca and Sr are partitioned differently between nutrient and mycorrhizal treatments and between plant fractions despite the common nutrient broth and substrate. Thus, Ca/Sr values alone are not reliable tracers of Ca within an ecosystem because of partitioning of Ca and Sr during nutrient transport within the plant-mycorrhizal system. We are presently refining analytical techniques and conducting leachate experiments to improve the quantification of this Ca/Sr fractionation. We are also exploring the use of isotopic tracers to study calcium biogeochemical cycling in forest ecosystems. (1) Blum, J.D., et al. 2002. Nature 417: 729-731. (2) Bailey, S.W., et al. 1996. Water Resources Research 32: 707-719. (3) Vitousek, P.M., et al. 1999. Oecologia 121: 255- 259.

Geochemistry of Woranso-Mille Pliocene basalts from west-central Afar, Ethiopia: Implications for mantle source characteristics and rift evolution

NASA Astrophysics Data System (ADS)

Alene, Mulugeta; Hart, William K.; Saylor, Beverly Z.; Deino, Alan; Mertzman, Stanley; Haile-Selassie, Yohannes; Gibert, Luis B.

2017-06-01

The Woranso-Mille (WORMIL) area in the west-central Afar, Ethiopia, contains several Pliocene basalt flows, tuffs, and fossiliferous volcaniclastic beds. We present whole-rock major- and trace-element data including REE, and Sr-Nd-Pb isotope ratios from these basalts to characterize the geochemistry, constrain petrogenetic processes, and infer mantle sources. Six basalt groups are distinguished stratigraphically and geochemically within the interval from 3.8 to 3 Ma. The elemental and isotopic data show intra- and inter-group variations derived primarily from source heterogeneity and polybaric crystallization ± crustal inputs. The combined Sr-Nd-Pb isotope data indicate the involvement of three main reservoirs: the Afar plume, depleted mantle, and enriched continental lithosphere (mantle ± crust). Trace element patterns and ratios further indicate the basalts were generated from spinel-dominated shallow melting, consistent with significantly thinned Pliocene lithosphere in western Afar. The on-land continuation of the Aden rift into western Afar during the Pliocene is reexamined in the context of the new geochemistry and age constraints of the WORMIL basalts. The new data reinforce previous interpretations that progressive rifting and transformation of the continental lithosphere to oceanic lithosphere allows for increasing asthenospheric inputs through time as the continental lithosphere is thinned. Accepted trace element values for BHVO-2 are those recently recommended by Jochum et al. (2016) rounded to provide the same significant figures as the data. Ternary model after Schilling et al. (1992); Endmembers from Rooney et al. (2012).

Geochemical and Crystallographic Study of Turbo Torquatus (Mollusca: Gastropoda) From Southwestern Australia

NASA Astrophysics Data System (ADS)

Roger, L. M.; George, A. D.; Shaw, J.; Hart, R. D.; Roberts, M. P.; Becker, T.; Evans, N. J.; McDonald, B. J.

2018-01-01

Shells of the marine gastropod Turbo torquatus were sampled from three different locations along the Western Australian coastline, namely Marmion Lagoon (31°S), Rottnest Island (32°S), and Hamelin Bay (34°S). Marmion Lagoon and Rottnest Island have similar sea surface temperature ranges that are ˜1°C warmer than Hamelin Bay, with all sites influenced by the warm southward flowing Leeuwin Current. The shells were characterized using crystallographic, spectroscopic, and geochemical analyses. Shell mineral composition varies between the three sites suggesting the influence of sea surface temperature, oxygen consumption, and/or bedrock composition on shell mineralogy and preferential incorporation and/or elemental discrimination of Mg, P, and S. Furthermore, T. torquatus was found to exert control over the incorporation of most, if not all, the elements measured here, suggesting strong biological regulation. At all levels of testing, the concentrations of Li varied significantly, which indicates that this trace element may not be a suitable environmental proxy. Variation in Sr concentration between sites and between specimens reflects combined environmental and biological controls suggesting that Sr/Ca ratios in T. torquatus cannot be used to estimate sea surface temperature without experimentally accounting for metabolic and growth effects. The mineral composition and microstructure of T. torquatus shells may help identify sea surface temperature variations on geological time scales. These findings support the previously hypothesized involvement of an active selective pathway across the calcifying mantle of T. torquatus for most, if not all, the elements measured here.

Identification of green pigments from fragments of Roman mural paintings of three Roman sites from north of Germania Superior

NASA Astrophysics Data System (ADS)

Debastiani, Rafaela; Simon, Rolf; Goettlicher, Joerg; Heissler, Stefan; Steininger, Ralph; Batchelor, David; Fiederle, Michael; Baumbach, Tilo

2016-10-01

Roman mural green pigment painting fragments from three Roman sites in the north of the Roman province Germania Superior: Koblenz Stadtwald Remstecken (KOSR), Weißenthurm " Am guten Mann" (WEIS) and Mendig Lungenkärchen (MELU), dating from second and third centuries AD were analyzed. The experiments were performed nondestructively using synchrotron-based scanning macro-X-ray fluorescence (SR-MA-XRF), synchrotron-based scanning micro-X-ray fluorescence (SR-μ-XRF), synchrotron-based X-ray diffraction (SR-XRD) and Raman spectroscopy. Correlation between SR-MA-XRF, SR-μ-XRF elemental map distributions and optical images of scanned areas was mainly found for the elements Ca, Fe and K. With XRF, Fe and K were identified correlated with green pigment, but in samples from two sites, Mendig Lungenkärchen and Weißenthurm " Am guten Mann", also Cu was detected in minor concentration. The results of SR-XRD and Raman spectroscopy were limited to one sample from Weißenthurm " Am guten Mann". In this sample, green earth and calcium carbonate were identified by SR-XRD and, additionally, malachite by Raman spectroscopy.

Quantitative Analysis of Trace Element Impurity Levels in Some Gem-Quality Diamonds

NASA Astrophysics Data System (ADS)

McNeill, J. C.; Klein-Bendavid, O.; Pearson, D. G.; Nowell, G. M.; Ottley, C. J.; Chinn, I.; Malarkey, J.

2009-05-01

Perhaps the most important information required to understand the origin of diamonds is the nature of the fluid that they crystallise from. Constraining the identity of the diamond-forming fluid for high purity gem diamonds is hampered by analytical challenges because of the very low analyte levels involved. Here we use a new ultra- low blank 'off-line' laser ablation method coupled to sector-field ICPMS for the quantitative analysis of fluid-poor gem diamonds. Ten diamonds comprised of both E- and P-type parageneses, from the Premier Mine, South Africa, were analysed for trace element abundances. We assume that the elemental signatures arise from low densities of sub-microscopic fluid inclusions that are analogous to the much higher densities of fluid inclusions commonly found within fluid-rich diamonds exhibiting fibrous growth. Repeatability of multiple (>20) blanks yielded consistently low values so that using the current procedure our limits of quantitation (10-ã blank) are <1pg for most trace elements, except for Sr, Zr, Ba, from 2-9pg and Pb ~30pg. Trace element patterns of the Premier diamond suite show enrichment of LREE over HREE. Abundances broadly decrease with increasing elemental compatibility. As a suite the chondrite normalised diamond patterns show negative Sr, Zr, Ti and Y anomalies and positive U, and Pb anomalies. All sample abundances are very depleted relative to chondrites (0.1 to 0.001X ch). HREE range from 0.1 to 1ppb as do Y, Nb, Cs. Other lighter elements vary from 2-30ppb. Pb reaches several ppb and Ti ranges from ppb values up to 2ppm. No significant difference were observed between the trace element systematics of the eclogitic and peridotitic diamonds. Overall, these initial data have inter-element fractionation patterns similar to those evident from fluid-rich fibrous diamonds and can be sued to infer that both types of diamond-forming fluids share a common origin.

Records of River Variation in the Shells of Freshwater Bivalves

NASA Astrophysics Data System (ADS)

Carroll, M.; Romanek, C.

2005-12-01

The skeletons of hard-shelled invertebrates such as corals and bivalves are commonly used in marine settings as archives of environmental information. They are less commonly used in freshwater settings where variability in water chemistry makes it more difficult to calibrate chemical proxies such as the Sr:Ca in a shell. Our objective is to evaluate whether trace element concentrations in freshwater bivalve shells contain information on environmental conditions. Multiple elements (Ba, Cu, Mn and Sr) were analyzed within the shells of modern bivalves from four streams on DOE's Savannah River Site in S.C. Laser Ablation ICP-MS was used to measure elemental concentrations across five aragonitic shells from each site. These elements were chosen because they are present in detectable concentrations (ppm) in the shell and they have been suggested as useful proxies for temperature, rainfall, productivity and pollution. Results were compared to historical monthly site records of water chemistry and chemical analyses of water samples collected from the streams where the clams were found. The average shell concentrations of Sr and Mn were significantly different between sites and increased proportionally to water concentration. This was not observed for Ba and Cu. For example, the Ba concentrations of shells collected at a site downstream of a lake were higher than those for shells from stream sites with significantly higher dissolved Ba concentrations. Copper was only detected at dark growth lines with the number of lines and shell material between them varying between shells within the same stream. Intrashell profiles of Ba, Sr and Mn concentrations exhibited cyclical variation. The magnitude of cyclical variation for Mn and Sr within a shell corresponds with the annual variation in monthly water sample concentrations. Again, this pattern was not observed for Ba, especially in shells from the site downstream of a lake. This supports suggestions that particulate organic matter, to which Ba preferentially partitions, plays a role in bivalve Ba uptake. Finally, variations in Ba, Cu, Mn and Sr profiles across shells are not in unison. The individual elemental responses to biological and physicochemical effects suggest that the elemental records in freshwater bivalve shells can be interpreted as environmental proxies.

Influence of bacteria on lanthanide and actinide transfer from specific soil components (humus, soil minerals and vitrified municipal solid waste incinerator bottom ash) to corn plants: Sr-Nd isotope evidence.

PubMed

Aouad, Georges; Stille, Peter; Crovisier, Jean-Louis; Geoffroy, Valérie A; Meyer, Jean-Marie; Lahd-Geagea, Majdi

2006-11-01

Experiments have been performed to test the stability of vitrified municipal solid waste (MSW) incinerator bottom ash under the presence of bacteria (Pseudomonas aeruginosa) and plants (corn). The substratum used for the plant growth was a humus-rich soil mixed with vitrified waste. For the first time, information on the stability of waste glasses in the presence of bacteria and plants is given. Results show that inoculated plant samples contained always about two times higher lanthanide and actinide element concentrations. Bacteria support the element transfer since plants growing in inoculated environment developed a smaller root system but have higher trace element concentrations. Compared with the substratum, plants are light rare earth element (LREE) enriched. The vitrified bottom ash has to some extent been corroded by bacteria and plant activities as indicated by the presence of Nd (REE) and Sr from the vitrified waste in the plants. (87)Sr/(86)Sr and (143)Nd/(144)Nd isotope ratios of plants and soil components allow the identification of the corroded soil components and confirm that bacteria accelerate the assimilation of elements from the vitrified bottom ash. These findings are of importance for landfill disposal scenarios, and similar experiments should be performed in order to better constrain the processes of microbially mediated alteration of the MSW glasses in the biosphere.

Magmatic evolution of lunar highland rocks estimated from trace elements in plagioclase: A new bulk silicate Moon model with sub-chondritic Ti/Ba, Sr/Ba, and Sr/Al ratios

NASA Astrophysics Data System (ADS)

Togashi, Shigeko; Kita, Noriko T.; Tomiya, Akihiko; Morishita, Yuichi

2017-08-01

The compositions of host magmas of ferroan anorthosites (FAN-host magmas) were estimated from secondary ion mass spectrometry analyses of plagioclase in lunar highland rocks. The evolution of the magmas was investigated by considering phase relations based on the MELTS algorithm and by re-examining partition coefficients for trace elements between plagioclase and melts. Data little affected by post-magmatic processes were selected by using plagioclase with relatively primitive Sc and Co contents. The FAN-host magma contained 90-174 ppm Sr, 40-119 ppm Ba and 0.5-1.3% TiO2, and had sub-chondritic Sr/Ba and Ti/Ba ratios. It is difficult to account for the formation of FAN-host magma on the basis of magma evolution processes of previously proposed bulk silicate Moon models with chondritic ratios for refractory elements at global scale. Therefore, the source of the FAN-host magma must have had primordial sub-chondritic Sr/Ba and Ti/Ba ratios. The FAN-host magmas were consistent in refractory elements with the estimated host mafic magma for feldspathic crust based on lunar meteorites, and some very-low-Ti mare rocks from lunar meteorites. Here, we propose an alternative bulk silicate Moon model (the cBSM model), which is enriched in crustal components of proto-bodies relative to the present whole Earth-Moon system.

Strontium attenuates rhBMP-2-induced osteogenic differentiation via formation of Sr-rhBMP-2 complex and suppression of Smad-dependent signaling pathway.

PubMed

Zhang, Wenjing; Tian, Yu; He, Hongyan; Chen, Rui; Ma, Yifan; Guo, Han; Yuan, Yuan; Liu, Changsheng

2016-03-01

Strontium (Sr(2+)) has pronounced effects on stimulating bone formation and inhibiting bone resorption in bone regeneration. In this current study, the effect and the underlying mechanism involved of Sr(2+) on the biological activity of bone morphogenetic protein-2 (BMP-2) were studied in detail with pluripotent skeletal muscle myogenic progenitor C2C12 model cell line. The results indicated that Sr(2+) could bind recombinant human BMP-2 (rhBMP-2) rapidly, even in the presence of Ca(2+) and Mg(2+), and inhibited rhBMP-2-induced osteogenic differentiation in vitro and osteogenetic efficiency in vivo. Further studies demonstrated that Sr(2+) treatment undermined the binding capacity of rhBMP-2 with its receptor BMPRIA and thus attenuated Smad 1/5/8 phosphorylation without affecting their dephosphorylation in C2C12 cells. Furthermore, circular dichroism spectroscopy, fluorescence spectroscopy and X-ray photoelectron spectroscopy all revealed that the inhibitory effect of Sr(2+) on the rhBMP-2 osteogenic activity was associated with the formation of Sr-rhBMP-2 complex and ensuing enhancement of β-sheet structure. Our work suggests the activity of rhBMP-2 to induce osteogenic differentiation was decreased by directly interaction with free Sr ions in solution, which should provide guide and assist for development of BMP-2-based materials for bone regeneration. Due to easy denaturation and ensuing the reduced activity of rhBMP-2, preserving/enhancing the capacity of rhBMP-2 to induce osteogenic differentiation is of critical importance in developing the protein-based therapy. Cations as effective elements influence the conformation and thereby the bioactivity of protein. Strontium (Sr(2+)), stimulating bone formation and inhibiting bone resorption, has been incorporated into biomaterials/scaffold to improve the bioactivity for bone-regeneration applications. However, Sr(2+)-induced changes in the conformation and bioactivity of BMP-2 have never been investigated. In this study, the formation of Sr-rhBMP-2 complex inhibited the osteogenic differentiation in vitro and osteogenetic efficiency in vivo through the inhibition of BMP/Smad signaling pathway, providing guidance for development of Sr-containing BMP-2-based bone scaffold/matrice and other Sr-dopped protein therapy. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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.

The granite problem as exposed in the southern Snake Range, Nevada

USGS Publications Warehouse

Lee, D.E.; Christiansen, E.H.

1983-01-01

A geochemically and mineralogically diverse group of granitoids is present within an area of 900 km2 in the southern Snake Range of eastern Nevada. The granitoids exposed range in age from Jurassic through Cretaceous to Oligocene and include two calcic intrusions, two different types of two-mica granites, and aplites. The younger intrusions appear to have been emplaced at progressively more shallow depths. All of these granitoid types are represented elsewhere in the eastern Great Basin, but the southern Snake Range is distinguished by the grouping of all these types within a relatively small area. The Jurassic calcic pluton of the Snake Creek-Williams Canyon area displays large and systematic chemical and mineralogical zonation over a horizontal distance of five km. Although major element variations in the pluton compare closely with Daly's average andesite-dacite-rhyolite over an SiO2 range of 63 to 76 percent, trace element (Rb, Sr, Ba) variations show that the zonation is the result of in situ fractional crystallization, with the formation of relatively mafic cumulates on at least one wall of the magma chamber. Models of trace element and isotopic data indicate that relatively little assimilation took place at the level of crystallization. Nonetheless, an initial 87Sr/86Sr value of 0.7071 and ??18O values of 10.2 to 12.2 permil suggest a lower crustal magma that was contaminated by upper crustal clastic sedimentary rocks before crystallization. The involvement of mantle-derived magmas in its genesis is difficult to rule out. Two other Jurassic plutons show isotopic and chemical similarities to the Snake Creek-Williams Canyon pluton. Cretaceous granites from eastern Nevada that contain phenocrystic muscovite are strongly peraluminous, and have high initial Sr-isotope ratios and other features characteristic of S-type granitoids. They were probably derived from Proterozoic metasediments and granite gneisses that comprise the middle crust of this region. Another group of granitoids (including the Tertiary aplites) show chemical, mineralogic, and isotopic characteristics intermediate between the first two groups and may have been derived by contamination of magmas from the lower crust by the midcrustal metasediments. ?? 1983 Springer-Verlag.

Strontium and Trace Metals in the Mississippi River Mixing Zone

NASA Astrophysics Data System (ADS)

Xu, Y.; Marcantonio, F.

2001-12-01

Strontium is generally believed to be a conservative element, i.e., it is assumed that dissolved Sr moves directly from rivers through estuaries to the ocean. More recently, however, detailed sampling of rivers suggests a weak non-conservative behavior for Sr. Here, we present dissolved and suspended load Sr and trace metal data for samples retrieved along salinity transects in the estuarine mixing zone of the Mississippi River. Our cruises took place during times representing high, falling, and low Mississippi River discharge. Sr concentration and isotopic composition were analyzed for both dissolved particulate loads. Selected particle-reactive or redox-sensitive trace metals (Mn, Fe, U, V, Mo, Ti, and Pb) were analyzed simultaneously. In the dissolved load, Sr showed conservative behavior in both high- and low- discharge periods. Non-conservative behavior of Sr predominated during falling discharge in the summer. Significant positive correlations were found between Sr, Mo and Ti. U and V distributions were found to be essentially controlled by mixing of river water and seawater, but with significantly lower riverine concentrations during high-flow stage. Particulate element concentrations can be quite variable and heterogeneous. In this study, strong correlations were found between particulate Mn (and Fe) concentrations and particulate concentrations of Ti, U, V, and Pb. No such correlations with Mn (or Fe) were found for particulate Sr and Mo. There is a vast hypoxic zone along the coast of Louisiana in the Gulf of Mexico that exists during the summer months. Based on the Sr isotope systematics and the relationships between Sr and trace metals, we believe that this eutrophication may contribute to the non-conservative behaviors of Sr and other trace metals. We discuss the potential implications of this hypothesis on the Sr mass balance of present-day and past seawater.

Chemical weathering on the North Island of New Zealand: CO2 consumption and fluxes of Sr and Os

NASA Astrophysics Data System (ADS)

Blazina, Tim; Sharma, Mukul

2013-09-01

We present Os and Sr isotope ratios and Os, Sr and major/trace element concentrations for river waters, spring waters and rains on the North Island of New Zealand. The Os and Sr data are used to examine whether the NINZ is a significant contributor of unradiogenic Os and Sr to the oceans. Major element chemistry is used to quantify weathering and CO2 consumption rates on the island to investigate relationships between these processes and Os and Sr behavior. Chemical erosion rates and CO2 consumption rates across the island range from 44 to 555 km-2 yr-1 and 95 to 1900 × 103 mol CO2 km-2 yr-1, respectively. Strontium flux for the island range from 177 to 16,100 mol km-2 yr-1 and the rivers have an average flux normalized 87Sr/86Sr ratio of 0.7075. In agreement with the previous studies these findings provide further evidence that weathering of arc terrains contributes a disproportionally large amount of Sr to the oceans and consumes very large amounts of CO2 annually compared to their areal extent. However, the 87Sr/86Sr from the NINZ is not particularly unradiogenic and it is likely not contributing significant amounts of unradiogenic Sr to the oceans. Repeated Os analyses and bottle leaching experiments revealed extensive and variable sample contamination by Os leaching from rigorously precleaned LDPE bottles. An upper bound on the flux of Os from NINZ can nevertheless be assessed and indicates that island arcs cannot provide significant amounts of unradiogenic Os to the oceans.

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.

Chemical and Sr isotopic characterization of North America uranium ores: Nuclear forensic applications

DOE PAGES

Balboni, Enrica; Jones, Nina; Spano, Tyler; ...

2016-08-31

This study reports major, minor, and trace element data and Sr isotope ratios for 11 uranium ore (uraninite, UO 2+x) samples and one processed uranium ore concentrate (UOC) from various U.S. deposits. The uraninite investigated represent ores formed via different modes of mineralization (e.g., high- and low-temperature) and within various geological contexts, which include magmatic pegmatites, metamorphic rocks, sandstone-hosted, and roll front deposits. In situ trace element data obtained by laser ablation-ICP-MS and bulk sample Sr isotopic ratios for uraninite samples investigated here indicate distinct signatures that are highly dependent on the mode of mineralization and host rock geology. Relativemore » to their high-temperature counterparts, low-temperature uranium ores record high U/Th ratios (>1000), low total rare earth element (REE) abundances (<1 wt%), high contents (>300 ppm) of first row transition metals (Sc, Ti, V, Cr, Mn, Co, Ni), and radiogenic 87Sr/ 86Sr ratios (>0.7200). Comparison of chondrite normalized REE patterns between uraninite and corresponding processed UOC from the same locality indicates identical patterns at different absolute concentrations. Lastly, this result ultimately confirms the importance of establishing geochemical signatures of raw, uranium ore materials for attribution purposes in the forensic analysis of intercepted nuclear materials.« less

Chemical and Sr isotopic characterization of North America uranium ores: Nuclear forensic applications

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

Balboni, Enrica; Jones, Nina; Spano, Tyler

This study reports major, minor, and trace element data and Sr isotope ratios for 11 uranium ore (uraninite, UO 2+x) samples and one processed uranium ore concentrate (UOC) from various U.S. deposits. The uraninite investigated represent ores formed via different modes of mineralization (e.g., high- and low-temperature) and within various geological contexts, which include magmatic pegmatites, metamorphic rocks, sandstone-hosted, and roll front deposits. In situ trace element data obtained by laser ablation-ICP-MS and bulk sample Sr isotopic ratios for uraninite samples investigated here indicate distinct signatures that are highly dependent on the mode of mineralization and host rock geology. Relativemore » to their high-temperature counterparts, low-temperature uranium ores record high U/Th ratios (>1000), low total rare earth element (REE) abundances (<1 wt%), high contents (>300 ppm) of first row transition metals (Sc, Ti, V, Cr, Mn, Co, Ni), and radiogenic 87Sr/ 86Sr ratios (>0.7200). Comparison of chondrite normalized REE patterns between uraninite and corresponding processed UOC from the same locality indicates identical patterns at different absolute concentrations. Lastly, this result ultimately confirms the importance of establishing geochemical signatures of raw, uranium ore materials for attribution purposes in the forensic analysis of intercepted nuclear materials.« less

Peripheral Ferroelectric Domain Switching and Polarization Fatigue in Nonvolatile Memory Elements of Continuous Pt/SrBi2Ta2O9/Pt Thin-Film Capacitors

NASA Astrophysics Data System (ADS)

Chen, Min-Chuan; Jiang, An-Quan

2011-07-01

We verify the domain sideway motion around the peripheral regions of the crossed capacitors of top and bottom electrode bars without electrode coverage. To avoid the crosstalk problem between adjacent memory cells, the safe distance between adjacent elements of Pt/SrBi2Ta2O9/Pt thin-film capacitors is estimated to be 0.156 μm. Moreover, the fatigue of Pt/SrBi2Ta2O9/Pt thin-film capacitors is independent of the individual memory size due to the absence of etching damage.

Biological forcing controls the chemistry of reef-building coral skeleton

NASA Astrophysics Data System (ADS)

Meibom, Anders; Mostefaoui, Smail; Cuif, Jean-Pierre; Dauphin, Yannicke; Houlbreque, Fanny; Dunbar, Robert; Constantz, Brent

2007-01-01

We present analyses of major elements C and Ca and trace elements N, S, Mg and Sr in a Porites sp. exoskeleton with a spatial resolution better than ˜150 nm. Trace element variations are evaluated directly against the ultra-structure of the skeleton and are ascribed to dynamic biological forcing. Individual growth layers in the bulk fibrous aragonite skeleton form on sub-daily timescales. Magnesium concentration variations are dramatically correlated with the growth layers, but are uncorrelated with Sr concentration variations. Observed (sub)seasonal relationships between water temperature and skeletal trace-element chemistry are secondary, mediated by sensitive biological processes to which classical thermodynamic formalism does not apply.

Chemical composition of modern and fossil hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

NASA Astrophysics Data System (ADS)

Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

2012-11-01

This study demonstrates that alkaline earth elements in enamel of hippopotamids, in particular Ba and Sr, are tracers for water provenance and hydrochemistry in terrestrial settings. The studied specimens are permanent premolar and molar teeth found in modern and fossil lacustrine sediments of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by two orders of magnitude for Ba (120-9336 μg g-1) as well as for Sr (9-2150 μg g-1). The variations are partially induced during post-mortem alteration and during amelogenesis, but the major contribution originates ultimately from the variable water chemistry in the habitats of the hippopotamids which is controlled by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of MgO, Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3-1.9. These elements are well correlated in single specimens, thus suggesting that their distribution is determined by a common, single process, which can be described by closed system Rayleigh crystallization of bioapatite in vivo. Enamel from most hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores. However, Ba/Sr ranges from 0.1 to 3 and varies on spatial and temporal scales. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic mantle rocks or Archean crustal rocks as the ultimate sources of Sr and Ba. This provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from 2 to 0.5. This trend can be correlated with changes in climate from humid to arid, in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water. The most plausible explanation is that Ba mobility decreased with increasing aridification due to preferential deposition with clay and Fe-oxide-hydroxide or barite on the watershed of Lake Albert.

Geochemical and Sr isotopic variations in groundwaters of the Edwards aquifer, central Texas

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

Oetting, G.C.; Banner, J.L.; Sharp, J.M. Jr.

1992-01-01

The regionally-extensive Edwards aquifer of central Texas lies on the northwestern edge of the Gulf of Mexico Basin. The aquifer system is composed primarily of lower Cretaceous marine limestones and dolostones with minor evaporitic and siliciclastic confining units of the Edwards Group and associated formations. The eastern and southern boundaries of the freshwater aquifer are defined by an abrupt change in groundwater salinity that is known as the badwater line. Variation in the isotopic composition and concentration of Sr in the mineral phases and waters in this aquifer system provide means to examine groundwater evolution processes. Models of simultaneous variationsmore » in Sr isotopes and major and trace ions are used to constrain processes of groundwater-rock interaction and groundwater mixing. Geochemical variations were examined in Edwards carbonate host rocks and groundwaters in Williamson and Bell Counties. Groundwaters were sampled along and across the badwater line, and range in salinity from 320--2,630 mg/l total dissolved solids. Major ion distributions in the water samples demonstrate a hydrochemical facies transition from Ca-HCO[sub 3] freshwaters to Na-Cl-SO[sub 4]-HCO[sub 3] badwaters. Both water types show a wide range of [sup 87]Sr/[sup 86]Sr values: Ca-HCO[sub 3] waters range from values of 0.7078--0.7093, and Na-Cl-SO[sub 4]-HCO[sub 3] waters range from values of 0.7087--0.7097. The Sr isotope compositions for both water groups are significantly greater than their host marine carbonates ([approximately]0.7075). The high Sr isotopic compositions indicate an extraformational source of Sr in both hydrochemical facies. Fluid mixing processes involving a freshwater and at least two badwater endmembers are required to account for variations in elemental and isotopic compositions in the groundwaters. Mineral-solution reactions may operate during and/or subsequent to mixing to produce the compositional variability observed in some intermediate waters.« less

Trace elements distribution in hawksbill turtle (Eretmochelys imbricata) and green turtle (Chelonia mydas) tissues on the northern coast of Bahia, Brazil.

PubMed

de Macêdo, Gustavo R; Tarantino, Taiana B; Barbosa, Isa S; Pires, Thaís T; Rostan, Gonzalo; Goldberg, Daphne W; Pinto, Luis Fernando B; Korn, Maria Graças A; Franke, Carlos Roberto

2015-05-15

Concentrations of elements (As, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Sr, V, Zn) were determined in liver, kidneys and bones of Eretmochelys imbricata and Chelonia mydas specimens found stranded along the northern coast of Bahia, Brazil. Results showed that the concentrations of Cd, Cu, Ni and Zn in the liver and kidneys of juvenile C. mydas were the highest found in Brazil. We also observed a significant difference (p<0.05) on the bioaccumulation of trace elements between the two species: Al, Co, Mo, Na and Se in the liver; Al, Cr, Cu, K, Mo, Ni, Pb, Sr and V in the kidneys; and Al, Ba, Ca, Cd, Mn, Ni, Pb, Se, Sr and V in the bones. This study represents the first report on the distribution and concentration of trace elements in E. imbricata in the Brazilian coast. Copyright © 2015 Elsevier Ltd. All rights reserved.

Some aspects of SR beamline alignment

NASA Astrophysics Data System (ADS)

Gaponov, Yu. A.; Cerenius, Y.; Nygaard, J.; Ursby, T.; Larsson, K.

2011-09-01

Based on the Synchrotron Radiation (SR) beamline optical element-by-element alignment with analysis of the alignment results an optimized beamline alignment algorithm has been designed and developed. The alignment procedures have been designed and developed for the MAX-lab I911-4 fixed energy beamline. It has been shown that the intermediate information received during the monochromator alignment stage can be used for the correction of both monochromator and mirror without the next stages of alignment of mirror, slits, sample holder, etc. Such an optimization of the beamline alignment procedures decreases the time necessary for the alignment and becomes useful and helpful in the case of any instability of the beamline optical elements, storage ring electron orbit or the wiggler insertion device, which could result in the instability of angular and positional parameters of the SR beam. A general purpose software package for manual, semi-automatic and automatic SR beamline alignment has been designed and developed using the developed algorithm. The TANGO control system is used as the middle-ware between the stand-alone beamline control applications BLTools, BPMonitor and the beamline equipment.

Dated eclogitic diamond growth zones reveal variable recycling of crustal carbon through time

NASA Astrophysics Data System (ADS)

Timmerman, S.; Koornneef, J. M.; Chinn, I. L.; Davies, G. R.

2017-04-01

Monocrystalline diamonds commonly record complex internal structures reflecting episodic growth linked to changing carbon-bearing fluids in the mantle. Using diamonds to trace the evolution of the deep carbon cycle therefore requires dating of individual diamond growth zones. To this end Rb-Sr and Sm-Nd isotope data are presented from individual eclogitic silicate inclusions from the Orapa and Letlhakane diamond mines, Botswana. δ13 C values are reported from the host diamond growth zones. Heterogeneous 87Sr/86Sr ratios (0.7033-0.7097) suggest inclusion formation in multiple and distinct tectono-magmatic environments. Sm-Nd isochron ages were determined based on groups of inclusions with similar trace element chemistry, Sr isotope ratios, and nitrogen aggregation of the host diamond growth zone. Diamond growth events at 0.14 ± 0.09, 0.25 ± 0.04, 1.1 ± 0.09, 1.70 ± 0.34 and 2.33 ± 0.02 Ga can be directly related to regional tectono-magmatic events. Individual diamonds record episodic growth with age differences of up to 2 Ga. Dated diamond zones have variable δ13 C values (-5.0 to -33.6‰ vs PDB) and appear to imply changes in subducted material over time. The studied Botswanan diamonds are interpreted to have formed in different tectono-magmatic environments that involve mixing of carbon from three sources that represent: i) subducted biogenic sediments (lightest δ13 C, low 87Sr/86Sr); ii) subducted carbonate-rich sediments (heavy δ13 C, high 87Sr/86Sr) and iii) depleted upper mantle (heavy δ13 C, low 87Sr/86Sr). We infer that older diamonds from these two localities are more likely to have light δ13 C due to greater subduction of biogenic sediments that may be related to hotter and more reduced conditions in the Archaean before the Great Oxidation Event at 2.3 Ga. These findings imply a marked temporal change in the nature of subducted carbon beneath Botswana and warrant further study to establish if this is a global phenomenon.

Geochemical and Isotopic (Sr, U) Tracing of Weathering Processes Controlling the Recent Geochemical Evolution of Soil Solutions in the Strengbach Catchment (Vosges, France)

NASA Astrophysics Data System (ADS)

Chabaux, F. J.; Prunier, J.; Pierret, M.; Stille, P.

2012-12-01

The characterization of the present-day weathering processes controlling the chemical composition of waters and soils in natural ecosystems is an important issue to predict and to model the response of ecosystems to recent environmental changes. It is proposed here to highlight the interest of a multi-tracer geochemical approach combining measurement of major and trace element concentrations along with U and Sr isotopic ratios to progress in this topic. This approach has been applied to the small granitic Strengbah Catchment, located in the Vosges Mountain (France), used and equipped as a hydro-geochemical observatory since 1986 (Observatoire Hydro-Géochimique de l'Environnement; http://ohge.u-strasbg.fr). This study includes the analysis of major and trace element concentrations and (U-Sr) isotope ratios in soil solutions collected within two soil profiles located on two experimental plots of this watershed, as well as the analysis of soil samples and vegetation samples from these two plots The depth variation of elemental concentration of soil solutions confirms the important influence of the vegetation cycling on the budget of Ca, K, Rb and Sr, whereas Mg and Si budget in soil solutions are quasi exclusively controlled by weathering processes. Variation of Sr, and U isotopic ratios with depth also demonstrates that the sources and biogeochemical processes controlling the Sr budget of soil solutions is different in the uppermost soil horizons and in the deeper ones, and clearly influence by the vegetation cycling.

Changing sources of strontium to soils and ecosystems across the Hawaiian Islands

USGS Publications Warehouse

Chadwick, O.A.; Derry, L.A.; Bern, C.R.; Vitousek, P.M.

2009-01-01

Strontium isotope ratios assist ecosystem scientists in constraining the sources of alkaline earth elements, but their interpretation can be difficult because of complexities in mineral weathering and in the geographical and environmental controls on elemental additions and losses. Hawaii is a "natural laboratory" where a number of important biogeochemical variables have either limited ranges or vary in systematic ways, providing a unique opportunity to understand the impact of time, climate, and atmospheric inputs on the evolution of base cation sources to ecosystems. There are three major sources of strontium (Sr) to these ecosystems, each with distinct isotopic compositions: basalt lava, Asian dust, and rainfall. We present Sr isotope and concentration data on both bulk soil digests and NH4Ac extracts from soil profiles covering a wide range of environments and substrate ages. Bulk soil material from dry climates and/or young substrate ages with > 80????g g- 1 Sr retain basalt-like Sr isotopic signatures, whereas those with Sr concentrations < 80????g g- 1 can have isotope signatures that range from basalt-like values to the more radiogenic values associated with continental dust. Although both dust accumulation and lava weathering are time- and rainfall-dependent, the overall concentration of Sr drops with increasing leaching even as quartz and mica derived from continental dust sources increase to > 40% by mass. At elevated dust levels, lava-derived Sr is low and dust-derived Sr is the dominant control of 87Sr/86Sr in bulk soils; however, 87Sr/86Sr of NH4Ac-extractable Sr largely reflects atmospheric deposition of marine aerosol in these situations. Overall, whole-soil Sr isotope values are controlled by complex interactions between Sr provided by lava weathering but partially lost by leaching, and Sr provided by dust but held in more resistant minerals. The isotopic composition of NH4Ac-extractable Sr and of the biota is controlled by lava weathering and rainfall contribution of Sr with only minor contributions from radiogenic dust sources. ?? 2009 Elsevier B.V.

Identifying the origins of local atmospheric deposition in the steel industry basin of Luxembourg using the chemical and isotopic composition of the lichen Xanthoria parietina.

PubMed

Hissler, Christophe; Stille, Peter; Krein, Andreas; Geagea, Majdi Lahd; Perrone, Thierry; Probst, Jean-Luc; Hoffmann, Lucien

2008-11-01

Trace metal atmospheric contamination was assessed in one of the oldest European industrial sites of steel production situated in the southern part of the Grand-Duchy of Luxembourg. Using elemental ratios as well as Pb, Sr, and Nd isotopic compositions as tracers, we found preliminary results concerning the trace metal enrichment and the chemical/isotopic signatures of the most important emission sources using the lichen Xanthoria parietina sampled at 15 sites along a SW-NE transect. The concentrations of these elements decreased with increasing distance from the historical and actual steel-work areas. The combination of the different tracers (major elements, Rare Earth Element ratios, Pb, Sr and Nd isotopes) enabled us to distinguish between three principal sources: the historical steel production (old tailings corresponding to blast-furnace residues), the present steel production (industrial sites with arc electric furnace units) and the regional background (baseline) components. Other anthropogenic sources including a waste incinerator and major roads had only weak impacts on lichen chemistry and isotopic ratios. The correlation between the Sr and Nd isotope ratios indicated that the Sr-Nd isotope systems represented useful tools to trace atmospheric emissions of factories using scrap metal for steel production.

Petrogenesis of Tertiary continental intra-plate lavas between Siebengebirge and Westerwald, Germany: Constraints from trace element systematics and Nd, Sr and Pb isotopes

NASA Astrophysics Data System (ADS)

Schubert, S.; Jung, S.; Pfänder, J. A.; Hauff, F.; Garbe-Schönberg, D.

2015-10-01

New 39Ar/40Ar ages and major- and trace-element and radiogenic isotope data are presented for basanites and alkali basalts from the transition area between the Westerwald and Siebengebirge volcanic fields (Germany) that belongs to the Central European Volcanic Province (CEVP). The 39Ar/40Ar ages indicate ages of c. 24 and c. 5 Ma which are fully compatible with previous K/Ar ages indicating that the evolution of this volcanic field belongs to the Westerwald area (28-22 Ma and 5 Ma) rather than to the Siebengebirge area (26-23 Ma). Based on the occurrence of > 30 isolated volcanic plugs with a simple igneous history, this volcanic field can be viewed as a monogenetic volcanic field. Compositions of some basanites are primitive, whereas others and the alkali basalts show decreasing Cr and Ni contents and CaO/Al2O3 ratios. However, increasing TiO2, Al2O3 and incompatible elements (Sr, Zr, Y, Hf, Ta) concentrations with decreasing MgO indicating fractionation of mainly olivine with minor amounts of clinopyroxene and spinel can be noticed. Rare earth element systematics suggest that most of the alkaline rocks are generated by different degrees of melting (5%-10%) of a garnet-bearing peridotite containing some residual amphibole. Negative anomalies of Rb and K in primitive mantle-normalized diagrams and a lack of Ba/Rb fractionation suggest that amphibole was the major OH-bearing mineral phase in the mantle. The alkaline rocks have a restricted range in 87Sr/86Sr and 143Nd/144Nd ratios ranging from 0.7033 to 0.7044 and from 0.51275 to 0.51285, respectively. Lead isotope compositions (206Pb/204Pb: 19.21-19.65; 207Pb/204Pb: 15.62-15.67; 208Pb/204Pb: 39.10-39.46) of the alkaline rocks are within the range of most OIB in which the higher values approach the composition of the European Asthenospheric Reservoir (EAR). The correlation between Sr and Nd isotopes and trace element constraints (Ce/Pb; Nb/U) indicates that for some samples interaction with crustal rocks during fractionation has occurred. Miocene intraplate basaltic volcanism in the area probably occurred as a result of minor "baby plume" activity. Each volcanic plug records evidence of a specific stage of fractionation with or without assimilation; however, in summary the lavas plot on a single fractionation path. This implies that during evolution of the volcanic field initial melting took place in the asthenosphere or at the lithosphere-asthenosphere interface. The melts moved through the lithospheric mantle and stagnated at crustal levels, however the observed fractionation paths suggest that they were fed from a single reservoir. This model, which involves small-scale plume impact followed by asthenosphere-lithosphere interaction together with minor crustal contamination, should also be applicable to other intra-continental rift-related areas.

Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

NASA Astrophysics Data System (ADS)

Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

2012-03-01

For reconstructing environmental change in terrestrial realms the geochemistry of fossil bioapatite in bones and teeth is among the most promising applications. This study demonstrates that alkaline earth elements in enamel of Hippopotamids, in particular Ba and Sr are tracers for water provenance and hydrochemistry. The studied specimens are molar teeth from Hippopotamids found in modern and fossil lacustrine settings of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by ca. two orders of magnitude for Ba (120-9336 μg g-1) as well as for Sr (9-2150 μg g-1). Concentration variations in enamel are partly induced during post-mortem alteration and during amelogenesis, but the major contribution originates from the variable water chemistry in the habitats of the Hippopotamids which is dominated by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3-1.5. These elements are well correlated with MgO and Na2O in single specimens, thus suggesting that their distribution is determined by a common, single process. Presuming that the shape of the tooth is established at the end of the secretion process and apatite composition is in equilibrium with the enamel fluid, the maturation process can be modeled by closed system Rayleigh crystallization. Enamel from many Hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores, but the compositions extend well into the levels of plants and carnivores. Within enamel from single specimens these element ratios covary and provide a specific fingerprint of the Hippopotamid habitat. All specimens together, however, define subparallel trends with different Ba/Sr ranging from 0.1 to 3. This ratio varies on spatial and temporal scales and traces provenance signals as well as the fractionation of the elements in the hydrological cycle. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic or Archean crustal rocks as the ultimate sources of Sr and Ba. The provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from about 2 to 0.5. This trend can be correlated with changes in climate from humid to arid in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water. The most plausible explanation is that with time, Ba mobility decreased relative to that of Sr. This can arise if preferential adsorption of Ba to clay and Fe-oxide-hydroxide is related to increasing aridification. Additionally, weathering solutions and lake water can become increasingly alkaline and barite becomes stable. In this case, Ba will be preferentially deposited on the watershed of Lake Albert and rivers with low Ba/Sr will feed the habitats of the Hippopotamids.

Species and life-history affects the utility of otolith chemical composition to determine natal stream-of-origin in Pacific salmon

USGS Publications Warehouse

Zimmerman, Christian E.; Swanson, Heidi K.; Volk, Eric C.; Kent, Adam J.R.

2013-01-01

To test the utility of otolith chemical composition as a tool for determining the natal stream of origin for salmon, we examined water chemistry and otoliths of juvenile and adult Chum Salmon Oncorhynchus keta and Coho Salmon O. kisutch from three watersheds (five rivers) in the Norton Sound region of Alaska. The two species are characterized by different life histories: Coho Salmon rear in freshwater for up to 3 years, whereas Chum Salmon emigrate from freshwater shortly after emergence. We used laser ablation (LA) inductively coupled plasma (ICP) mass spectrometry (MS) to quantify element: Ca ratios for Mg, Mn, Zn, Sr, and Ba, and we used multicollector LA-ICP-MS to determine 87Sr:86Sr ratios in otolith regions corresponding to the period of freshwater residence. Significant differences existed in both water and otolith elemental composition, suggesting that otolith composition could be used to discriminate the natal origin of Coho Salmon and Chum Salmon but only when 87Sr:86Sr ratios were included in the discriminant function analyses. The best discriminant model included 87Sr:86Sr ratios, and without 87Sr:86Sr ratios it was difficult to discriminate among watersheds and rivers. Classification accuracy was 80% for Coho Salmon and 68% for Chum Salmon, indicating that this method does not provide sufficient sensitivity to estimate straying rates of Pacific salmon at the scale we studied.

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.

Seasonal growth and translocation of some major and trace elements in two Mediterranean grasses (Stipa tenacissima Loefl. ex L. and Lygeum spartum Loefl. ex L.)

NASA Astrophysics Data System (ADS)

Nedjimi, Bouzid

2018-05-01

The rangelands of Stipa tenacissima and Lygeum spartum (Poaceae) constitute one of the main typical ecosystems in the Iberian Peninsula and North Africa. This study examines the seasonal changes in aboveground biomass accumulation and translocation of some major (Ca and K) and trace elements (Br, Cr, Cu, Fe, Mn, Sr and Zn) from topsoil to shoots of these perennial grasses. Species, season and their interaction significantly affected the dry biomass (DW) and chemical composition of both species and their surrounding soil. The maximum DW was found in spring due to high physiological activity and was correlated positively with rainfall. A significant relationship between seasons and chemical elements was found. For both species the maximum concentrations of Ca, Cu and Zn were found in spring season. However L. spartum had the highest concentrations of K, Cr, Br, and Sr in autumn season, indicating exceptional ability of these species to accumulate large contents of these elements during the active growth periods. By way of contrast, in the topsoil the highest concentrations of almost all chemical elements were found in summer and autumn. Principal component analyses (PCA) showed that growth of L. spartum was highly associated with K, Ca, Zn, Br and Sr, whereas topsoil was correlated with Cu, Cr, Fe and Mn concentrations. Translocation factor (TFx) of chemical elements was not identical across the two species, demonstrating inter-specific variability to uptake chemical elements. The maximum values of TFx were recorded for K, Ca and Sr especially for L. spartum. To cope with arid conditions, S. tenacissima and L. spartum sprout quickly by increasing their rate of growth and nutrient uptake as soon as soil water is available after the rain.

Accumulation of alkaline earth metals by the green macroalga Bryopsis maxima.

PubMed

Takahashi, Shigekazu; Aizawa, Kyoko; Nakamura, Saki; Nakayama, Katsumi; Fujisaki, Shingo; Watanabe, Soichiro; Satoh, Hiroyuki

2015-04-01

Twenty-five days after the disaster at the Fukushima Daiichi nuclear power plant in 2011, we collected samples of the green macroalga Bryopsis maxima from the Pacific coast of Japan. Bryopsis maxima is a unicellular, multinuclear, siphonous green macroalga. Radiation analysis revealed that B. maxima emitted remarkably high gamma radiation of (131)I, (134)Cs, (137)Cs, and (140)Ba as fission products of (235)U. Interestingly, B. maxima contained naturally occurring radionuclides derived from (226)Ra and (228)Ra. Analysis of element content revealed that B. maxima accumulates many ocean elements, especially high quantities of the alkaline earth metals Sr (15.9 g per dry-kg) and Ba (3.79 g per dry-kg), whereas Ca content (12.5 g per dry-kg) was lower than that of Sr and only 61 % of the mean content of 70 Japanese seaweed species. Time-course analysis determined the rate of radioactive (85)Sr incorporation into thalli to be approximately 0.13 g Sr per dry-kg of thallus per day. Subcellular fractionation of B. maxima cells showed that most of the (85)Sr was localized in the soluble fraction, predominantly in the vacuole or cytosol. Given that (85)Sr radioactivity was permeable through a dialysis membrane, the (85)Sr was considered to be a form of inorganic ion and/or bound with a small molecule. Precipitation analysis with sodium sulfate showed that more than 70% of the Sr did not precipitate as SrSO4, indicating that a proportion of the Sr may bind with small molecules in B. maxima.

Selectivity in biomineralization of barium and strontium.

PubMed

Krejci, Minna R; Wasserman, Brian; Finney, Lydia; McNulty, Ian; Legnini, Daniel; Vogt, Stefan; Joester, Derk

2011-11-01

The desmid green alga Closterium moniliferum belongs to a small number of organisms that form barite (BaSO(4)) or celestite (SrSO(4)) biominerals. The ability to sequester Sr in the presence of an excess of Ca is of considerable interest for the remediation of (90)Sr from the environment and nuclear waste. While most cells dynamically regulate the concentration of the second messenger Ca(2+) in the cytosol and various organelles, transport proteins rarely discriminate strongly between Ca, Sr, and Ba. Herein, we investigate how these ions are trafficked in C. moniliferum and how precipitation of (Ba,Sr)SO(4) crystals occurs in the terminal vacuoles. Towards this goal, we simultaneously visualize intracellular dynamics of multiple elements using X-ray fluorescence microscopy (XFM) of cryo-fixed/freeze-dried samples. We correlate the resulting elemental maps with ultrastructural information gleaned from freeze-fracture cryo-SEM of frozen-hydrated cells and use micro X-ray absorption near edge structure (micro-XANES) to determine sulfur speciation. We find that the kinetics of Sr uptake and efflux depend on external Ca concentrations, and Sr, Ba, and Ca show similar intracellular localization. A highly ion-selective cross-membrane transport step is not evident. Based on elevated levels of sulfate detected in the terminal vacuoles, we propose a "sulfate trap" model, where the presence of dissolved barium leads to preferential precipitation of (Ba,Sr)SO(4) due to its low solubility relative to SrSO(4) and CaSO(4). Engineering the sulfate concentration in the vacuole may thus be the most direct way to increase the Sr sequestered per cell, an important consideration in using desmids for phytoremediation of (90)Sr. Copyright © 2011 Elsevier Inc. All rights reserved.

Granitoids of different geodynamic settings of Baikal region (Russia) their geochemical evolution and origin

NASA Astrophysics Data System (ADS)

Antipin, Viktor; Sheptyakova, Natalia

2016-04-01

In the southern folded framing of the Siberian craton the granitoid magmatism of different ages involves batholiths, small low-depth intrusions and intrusion-dyke belts with diverse mineral and geochemical characteristics of rocks. Granitoid formation could be related to the Early Paleozoic collision stage and intra-plate magmatism of the Late Paleozoic age of the geologic development of Baikal area. The Early Paleozoic granitoids of Khamar-Daban Ridge and Olkhon region revealed their closeness in age and composition. They were referred to syncollision S-type formations derived from gneiss-schistose substratum of metamorphic sequences. The magmatic rocks were classified into various geochemical types comprising formations of normal Na-alkalinity (migmatites and plagiogranites), calc-alkaline and subalkaline (K-Na granitoids, granosyenites and quartz syenites) series. It is significant, that plagiomigmatites and plagiogranites in all elements repeat the shape of the chart of normalized contents marked for trend of K-Na granitoids, but at considerably lower level of concentrations of all elements. This general pattern of element distribution might indicate similar anatectic origin of both granitoid types, but from crustal substrata distinguished by composition and geochemical features. Comparative geochemical analysis pointed out that the source of melts of the Early Paleozoic granitoids of the Olkhon (505-477 Ma) and Khamar-Daban (516-490 Ma) complexes of the Baikal region could be the crustal substratum, which is obviously the criterion for their formation in the collisional geodynamic setting. Using the Late Paleozoic subalkaline magmatism proceeding at the Khamar-Daban Range (Khonzurtay pluton, 331 Ma) as an example, it was found that the formation of monzodiorite-syenite-leucogranite series was considerably contributed by the processes of hybridism and assimilation through mixing of the upper mantle basaltoid magma derived melts of granitic composition. The involvement of the deep source is indicated by low Rb/Sr ratios and 87Sr/86Sr ratio (0.70592±0.00021) in rocks (Kazimirovskiy, 2006). The intra-plate biotite granites and leucogranites are represented by rare-metal geochemical type of rocks (311-321 Ma). Geochemical evolution promoted an increase of F, Li, Rb, Cs, Sn, Be, Ta, and Pb and a decrease of Ba, Sr, Zn, Zr, Th, and U contents in rare-metal granites, that reflects their formation from deeply differentiated residual magma. The substance of the lower crust could have the composition of biotite-bearing granulites rich in lithophyle rare elements. It is noteworthy, that the composition and isotope-geochemical features of the supposed magma-forming substratum correspond to the characteristics of the ancient Precambrian continental crust of the Southern Baikal region. These conclusions agree with the results of preceding studies of rare-metal granites in the other regions of Central Asia (Kovalenko et al, 1999). Research has been supported by RNF grant № 15-17-10010.

87Sr/88Sr a useful tool for the identification of geographic origin of Styrian pumpkin seed oils?

NASA Astrophysics Data System (ADS)

Meisel, T.; Bandoniene, D.; Zettl, D.; Maneiko, M.; Horschinegg, M.

2012-04-01

The authenticity and the geographic origin of Styrian pumpkin seed oil (PGI) a regional specialty needs to be protected, but the current specification of this high priced product does not include the proof of origin through analytical tools. As it turns out, this and many other products within the Protected Geographical Status (PGS) framework of the European Union, cannot be protected from fraud without forensic tools. In previous studies we were able to demonstrate, that distribution and content of trace elements in particular the rare earth elements, are useful parameters to discriminate Austrian from non-Austrian pumpkin seed oils and seeds. Unlike stable isotopes ratios (C and H), the trace element patterns are not influenced by changes in weather conditions and temperature during growing and harvesting cycle. Though the study of the distribution of element traces can be used not only for the identification of the geographic origin with very useful PLS and PCA models but also can identify fraud through mixing with other oils, this method need to be validated by other means. Radiogenic isotopes, in particular the 87Sr/86Sr isotope amount ratio has been successfully applied to food and other products for forensic studies. In this study we determined the 87Sr/86Sr isotope amount ratio in pumpkin seed oils extracted from seeds of known geographic origin from Austria, Russia and China, as these are the largest producers, to see if significant differences occur and if they can be used as a forensic tool. Although the total area of the Russian and the Chinese crop fields are magnitudes larger than the ones from Austria, it turns out that the variance of the Austrian 87Sr/86Sr data is much larger than that from other sources. Reasons are the large diversity of the Austrian geology (pre-varsican, alpine to sub-recent ages of the underlying bedrock of the soils can be found), the small farm sizes and the small scale production. In Russia large farms are situated on homogeneous bedrock and are also influenced by sea spray. On the other hand, in China cooperatives collect and probably homogenize seeds from many small farms in a geologically relatively homogeneous area in China (Inner Mongolia). Through these differences expressed in geology, farm size and production type, the radiogenic strontium isotopic composition is thus a useful and complementary addition to the existing classification method based on element trace contents and patterns but it cannot substitute the existing method.

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.

Estimating the over-involvement of suspended, revoked, and unlicensed drivers as at-fault drivers in California fatal crashes.

PubMed

Brar, Sukhvir S

2014-09-01

Quasi-induced exposure analysis was used to estimate annual fatal crash involvement rates for validly licensed, suspended or revoked (S/R), and unlicensed drivers in California from 1987 through 2009 using fatal crash data obtained from the National Highway Traffic Safety Administration's Fatality Analysis Reporting System and crash culpability determinations from the California Highway Patrol's Statewide Integrated Traffic Records System. Although there was some year-to-year fluctuation in the annual estimates, S/R and unlicensed drivers were over-involved as at-fault drivers in fatal crashes during every year of the 23-year time period relative to validly licensed drivers. The fatal crash involvement ratios combined across all years were 0.86 for validly licensed drivers, 2.23 for S/R drivers, and 2.34 for unlicensed drivers. Hence, compared to validly licensed drivers, the odds of being at-fault for a fatal crash were 160% higher for S/R drivers (involvement ratio=2.60) and 173% higher for unlicensed drivers (involvement ratio=2.73). The excess risks of S/R and unlicensed drivers are somewhat lower than estimates found in a prior study using the same technique, but the results nonetheless provide evidence that S/R and unlicensed drivers are much more hazardous on the road than are validly licensed drivers and emphasize the importance of using strong countermeasures-including vehicle impoundment-to reduce their high crash risk. These findings support interventions to help reduce driving among S/R and unlicensed drivers. Published by Elsevier Ltd.

Rapid Mantle Source Variations During the Latest Episode of Kilauea's Prolonged Pu'u O'o Eruption, Hawaii

NASA Astrophysics Data System (ADS)

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

2006-12-01

Nearly 24 years of continuous geochemical monitoring of lavas from the current Pu'u O'o eruption allow us to probe the mantle processes beneath Kilauea Volcano in unparalleled detail. Here we present new measurements Pb, Sr, and Nd isotope ratios and major- and trace-element abundances for lavas from episode 55 (1997-2006), which marks the longest and most voluminous interval of this eruption. Pu'u O'o lavas erupted since 1985 display systematic decreases in their TiO2, K2O, P2O5 and CaO abundances (normalized to 10 wt. % MgO to correct for olivine control) due to changes in the parental magma composition. Incompatible element ratios (e.g., Ba/Nb and La/Y) also show overall temporal decreases. Earlier erupted Pu'u O'o lavas displayed the most significant decrease in incompatible element ratios with near constant SiO2 contents, and a gradual increase in 87Sr/86Sr ratios. However, episode 55 lavas record significant increases in MgO- normalized SiO2 contents and 87Sr/86Sr with nearly constant (e.g. Ba/Nb) or a slightly reversed (e.g., TiO2 and K2O) trends in incompatible element ratios and abundances. There is little variation of 206Pb/204Pb ratios in lavas (18.38-18.43) erupted since 1985. Neither a single mantle source composition nor a change in partial melting conditions alone can explain these observations. Based on the isotopic and chemical variability, we conclude that early Pu'u O'o lavas originated from two distinct mantle source components: (1) a long-term depleted component (with relatively low 87Sr/86Sr ratios) that originated within the deep source of the Hawaiian plume that characterizes the earlier part of the eruption (1985-1992), and (2) a recently depleted component (i.e. a component that was recently depleted by prior melting) with low abundances of incompatible elements became increasingly important from 1992-1997. More recently, Pu'u O'o has tapped greater proportions of a new (3) long-term less depleted component (with higher 87Sr/86Sr ratios than observed from 1985-1992) that originated within the deep source region of the plume. This third 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. The systematic geochemical evolution of Pu'u O'o lavas reflects changes in the proportions of the mantle source components tapped throughout the eruption. The rapid isotope variations (on a time scale of years) in the most recent lavas suggest the mantle source components are heterogeneous on an extremely small scale, relative to the size of Kilauea's melting region.

Superconductivity up to 114 K in the Bi-Al-Ca-Sr-Cu-O compound system without rare-earth elements

NASA Technical Reports Server (NTRS)

Chu, C. W.; Bechtold, J.; Gao, L.; Hor, P. H.; Huang, Z. J.

1988-01-01

Stable superconductivity up to 114 K has been reproducibly detected in Bi-Al-Ca-Sr-Cu-O multiphase systems without any rare-earth elements. Pressure has only a slight positive effect on T(c). These observations provide an extra material base for the study of the mechanism of high-temperature superconductivity and also the prospect of reduced material cost for future applications of superconductivity.

Subduction-like fluids in the genesis of Mt. Etna magmas: evidence from boron isotopes and fluid mobile elements

NASA Astrophysics Data System (ADS)

Tonarini, Sonia; Armienti, Pietro; D'Orazio, Massimo; Innocenti, Fabrizio

2001-11-01

New whole-rock B, Sr, Nd isotope ratios and 87Sr/ 86Sr on clinopyroxenes have been collected to study the enrichment of fluid mobile elements (FMEs) observed in Mt. Etna volcanics. Etna volcano, one of the most active in the world, is located in an extremely complex tectonic context at the boundary between colliding African and European plates. The analytical work focuses on current (1974-1998) and historic (1851-1971) eruptive activity, including some key prehistoric lavas, in order to interpret the secular shift of its geochemical signature to more alkaline compositions. Boron is used as a tool to unravel the role of fluids in the genesis of magmas, revealing far-reaching consequences, beyond the case study of Mt. Etna. Small variations are observed in δ 11B (-3.5 to -8.0‰), 87Sr/ 86Sr (0.70323-0.70370), and 143Nd/ 144Nd (0.51293-0.51287). Moreover, temporal evolution to higher δ 11B and 87Sr/ 86Sr, and to lower 143Nd/ 144Nd, is observed in the current activity, defining a regular trend. Sr isotopic equilibrium between whole-rock and clinopyroxene pairs indicates the successive introduction of three distinct magma types into the Etna plumbing system over time; these are characterized by differing degrees of FME enrichment. In addition, certain lavas exhibit evidence for country rock assimilation, magma-fluid interaction, or magma mixing in the shallow feeding system; at times these processes apparently lowered magmatic δ 11B and/or induced Sr isotopic disequilibrium between whole rock and clinopyroxene. The regular increase of δ 11B values is correlated with Nb/FME and 87Sr/ 86Sr ratios; these correlations are consistent with simple mixing between the mantle source and aqueous fluids derived from nearby Ionian slab. The best fit of Mt. Etna data is obtained using an enriched-MORB mantle source and a fluid phase with δ 11B of about -2‰ and 87Sr/ 86Sr of 0.708. We argue that the slab window generated by differential roll-back of subducting Ionian lithosphere (with respect to Sicily) allows the upwelling of asthenosphere from below the subduction system and provides a suitable path of rise for subduction-related fluids. The increasing geochemical signature of fluid mobile elements enrichment to Mt. Etna lavas is considered a consequence of the progressive opening of slab window through time.

A Geochemical View on the Interplay Between Earth's Mantle and Crust

NASA Astrophysics Data System (ADS)

Chauvel, C.

2017-12-01

Over most of Earth history, oceanic and continental crust was created and destroyed. The formation of both types of crust involves the crystallization and differentiation of magmas producing by mantle melting. Their destruction proceeds by mechanical erosion and weathering above sea level, chemical alteration on the seafloor, and bulk recycling in subduction zones. All these processes enrich of some chemical element and deplete others but each process has its own effect on chemical elements. While the flux of material from mantle to crust is well understood, the return flux is much more complex. In contrast to mantle processes, erosion, weathering, chemical alteration and sedimentary processes strongly decouple elements such as the rare earths and high-field strength elements due to their different solubilities in surface fluids and mineralogical sorting during transport. Soluble elements such as strontium or uranium are quantitatively transported to the ocean by rivers and decoupled from less soluble elements. Over geological time, such decoupling significantly influences the extent to which chemical elements remain at the Earth's surface or find their way back to the mantle through subduction zones. For example, elements like Hf or Nd are retained in heavy minerals on continents whereas U and Sr are transported to the oceans and then in subduction zones to the mantle. The consequence is that different radiogenic isotopic systems give disparate age estimates for the continental crust; e.g, Hf ages could be too old. In subduction zones, chemical elements are also decoupled, due to contrasting behavior during dehydration or melting in subducting slabs. The material sent back into the mantle is generally enriched in non-soluble elements while most fluid-mobile elements return to the crust. This, in turn, affects the relationship between the Rb-Sr, Sm-Nd, Lu-Hf and U-Th-Pb isotopic systems and creates correlations unlike those based on magmatic processes. By quantifying the difference between isotopic arrays created by magmatic processes vs. surface and subduction processes, we can determine how crust recycling creates isotopic heterogeneities in the mantle.

Petrology and chemistry of Permian coals from the Paraná Basin: 1. Santa Terezinha, Leão-Butiá and Candiota Coalfields, Rio Grande do Sul, Brazil

USGS Publications Warehouse

Kalkreuth, W.; Holz, M.; Kern, M.; Machado, G.; Mexias, A.; Silva, M.B.; Willett, J.; Finkelman, R.; Burger, H.

2006-01-01

Hierarchical cluster analysis identified three groups of major minerals and seven groups of trace elements based on similarity levels. On a regional scale, the coalfields can be separated by the differences in rank (Candiota and Leão-Butiá versus Santa Terezinha) and by applying discriminant analysis based on 4 trace elements (Li, As, Sr, Sb). Highest Rb and Sr values occur at Candiota and are linked to syngenetic volcanism of the area, whereas high Y and Sr values at Santa Terezinha can be related to the frequent diabase intrusions in that area.

Evolution of the lithospheric mantle beneath Mt. Baekdu (Changbaishan)

NASA Astrophysics Data System (ADS)

Choi, S. H.; Park, K.; Cho, M.; Lee, D. C.

2017-12-01

Major and trace element compositions of minerals as well as Sr-Nd-Hf isotopic compositions of clinopyroxenes from spinel peridotite xenoliths entrained in Late Cenozoic trachybasalt from Mt. Baekdu (Changbaishan) were used to elucidate lithospheric mantle formation and evolution in the eastern North China Craton (NCC). The analyzed peridotites were mainly spinel lherzolites with rare harzburgites. They consisted of olivine, enstatite, diopside and spinel. Plots of the Cr# in spinel against the Mg# in coexisting olivine or spinel suggested an affinity with abyssal peridotites. Comparisons of Cr# and TiO2 in spinel were also compatible with an abyssal peridotite-like composition; however, harzburgites were slightly enriched in TiO2 because of the reaction with MORB-like melt. Temperatures estimated using two-pyroxene thermometry ranged from 750 to 1,010°C, reflecting their lithospheric mantle origin. The REE patterns in clinopyroxenes of the peridotites varied from LREE-depleted to spoon shaped to LREE-enriched, reflecting secondary overprinting effects of metasomatic melts or fluids on the residues from primordial melting. The calculated trace element pattern of metasomatic melt equilibrated with clinopyroxene in Mt. Baekdu peridotite showed strong enrichment in LILEs, Th and U together with slight fractionation in HREEs and considerable depletion in Nb and Ti. The Sr-Nd-Hf isotopic compositions of clinopyroxenes separated from the peridotites varied from more depleted than present-day MORB to bulk Earth values. However, some clinopyroxene showed a decoupling between Nd and Sr isotopes, deviating from the mantle array with a high 87Sr/86Sr ratio. This sample also showed a significant Nd-Hf isotope decoupling lying well above the mantle array. The Lu-Hf and Sm-Nd model ages of residual clinopyroxenes yielded Early Proterozoic to Phanerozoic ages. No signature of Archean cratonic mantle was present. Therefore, Mt. Baekdu peridotite is residual lithospheric mantle that has undergone variable degrees of diachronous melt extraction and infiltration metasomatism involving subduction-related, fluid-bearing silicate melts. The predominance of Phanerozoic Hf model ages indicates that the lherzolites represent lithospheric mantle fragments newly accreted underneath the eastern NCC.

Microchemical evidence for episodic growth of antitaxial veins during fracture-controlled fluid flow

NASA Astrophysics Data System (ADS)

Barker, Shaun L. L.; Cox, Stephen F.; Eggins, Stephen M.; Gagan, Michael K.

2006-10-01

The mechanism by which syntectonic hydrothermal veins form is widely debated, with some workers suggesting that certain vein textures are related to specific fluid flow regimes. Central to the debate is whether vein formation involves advective fluid flow, or occurs by local diffusion of material from the surrounding wall rock. To address this issue, we integrated textural observations and microchemical analyses of a hydrothermal vein from the Lachlan Orogen, southeast Australia, to reveal information about vein growth history, changes in fluid chemistry, and the evolution of fluid flow pathways during vein growth. The study area is part of a regional-scale fault-fracture network in an interbedded limestone-shale sequence, which formed at depths of ˜ 5-10 km (˜ 150-200 °C) during late Devonian crustal shortening. This integrated approach demonstrates that the zonation of textures, Sr isotopes, stable isotopes (C, O), and trace and rare earth elements is distinctly asymmetrical about the median growth-line of the vein. δ 18O values in vein calcite (17.0-18.8‰, VSMOW) are lower than those in surrounding unaltered limestones (23-25‰, VSMOW), and vary systematically across the vein. In contrast, δ 13C values are relatively constant across most of the vein, but become markedly depleted ( ca. 4‰) immediately adjacent to the wall rock. This strong depletion in δ 13C was probably caused by the influx of more oxidised fluids during the latest stages of vein growth. Strontium isotope ratios ( 87Sr/ 86Sr) vary between 0.70912 and 0.70931 across the vein. Abrubt changes in 87Sr/ 86Sr, δ 18O, Ce/Ce *, Eu/Eu * and trace element concentrations indicate that vein growth was accompanied by stepwise changes in the fluid flow pathway and consequent variations in fluid chemistry. Taken together, our findings are not consistent with growth of fibrous antitaxial veins by diffusional transfer of material from the surrounding wall rock. Instead, they suggest that externally sourced fluids migrated along episodically changing fracture-controlled flow pathways. This has implications for the dynamics of crustal permeability and mineralisation.

PIXE as a complement to ICP-OES trace metal analysis in Sudanese medicinal plants.

PubMed

Mubark Ebrahim, Ammar; Etayeb, M A; Khalid, H; Noun, Manale; Roumie, M; Michalke, B

2014-08-01

This paper compares trace element concentrations (Ca, K, Sr, Fe, Mn, Zn, Ni, Cu, Co and Cr) in 27 Sudanese medical plants determined in parallel by PIXE and ICP-OES to get information on which technique is preferable at different matrices and element concentrations. PIXE correlates well to ICP-OES for Sr, Mn, Ca, K, Zn and Fe determinations. ICP-OES seems to be the superior technique over PIXE when measuring low concentrated elements (chromium, cobalt, nickel and copper) in the medicinal plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microbial Immobilization of Si, Mn, Fe, and Sr Ions in the Nacreous Layer of Sinohyliopsis schlegeli and Environmental Factors

NASA Astrophysics Data System (ADS)

Tazaki, Kazue; Morii, Issei

Environmental changes recorded in the shell nacre of Sinohyliopsis schlegeli were observed with elemental factors of characteristic water and nutrition for eight months in a cultivated drainage pond at Kanazawa University, Ishikawa Prefecture, Japan. Tetracycline as an indicator was injected into the shell nacre once every month from May to November in 2007. Water qualities such as the pH, redox potential, electrical conductivity, dissolved oxygen concentration, and water temperature were measured periodically, and the suspended solids in the water were removed by filtration for optical microscopy, X-ray fluorescence analysis, and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) observations. X-ray fluorescence chemical analysis of shell nacre indicated layers with strong tetracycline accumulation corresponding to high concentrations of Si, Mn, Fe, and Sr ions. The redox potential and dissolved oxygen concentration measurements supported the existence of layers in the nacre. The suspended materials in the drainage pond water comprised mainly of Si, Mn, and Fe elements, which were the same elements involved in microbial immobilization in the shell nacre during the summer of 2007. SEM-EDX analyses confirmed that the ions originated from diatoms, Siderocapsa sp. and Gallionella ferruginea in the stomach. There was little microbial immobilization of the ions in winter. The results suggested elemental immobilization in the layered shell nacre and indicated that Sinohyliopsis schlegeli fed on the ions, to grow the nacre during summer. Sinohyliopsis schlegeli with these biogenic oxides might contribute to the scavenging of heavy metals in natural water.

Sources of granite magmatism in the Embu Terrane (Ribeira Belt, Brazil): Neoproterozoic crust recycling constrained by elemental and isotope (Sr-Nd-Pb) geochemistry

NASA Astrophysics Data System (ADS)

Alves, Adriana; Janasi, Valdecir de Assis; Campos Neto, Mario da Costa

2016-07-01

Whole rock elemental and Sr-Nd isotope geochemistry and in situ K-feldspar Pb isotope geochemistry were used to identify the sources involved in the genesis of Neoproterozoic granites from the Embu Terrane, Ribeira Belt, SE Brazil. Granite magmatism spanned over 200 Ma (810-580 Ma), and is dominated by crust-derived relatively low-T (850-750 °C, zircon saturation) biotite granites to biotite-muscovite granites. Two Cryogenian plutons show the least negative εNdt (-8 to -10) and highest mg# (30-40) of the whole set. Their compositions are strongly contrasted, implying distinct sources for the peraluminous (ASI ∼ 1.2) ∼660 Ma Serra do Quebra-Cangalha batholith (metasedimentary rocks from relatively young upper crust with high Rb/Sr and low Th/U) and the metaluminous (ASI = 0.96-1.00) ∼ 630 Ma Santa Catarina Granite. Although not typical, the geochemical signature of these granites may reflect a continental margin arc environment, and they could be products of a prolonged period of oceanic plate consumption started at ∼810 Ma. The predominant Ediacaran (595-580 Ma) plutons have a spread of compositions from biotite granites with SiO2 as low as ∼65% (e.g., Itapeti, Mauá, Sabaúna and Lagoinha granites) to fractionated muscovite granites (Mogi das Cruzes, Santa Branca and Guacuri granites; up to ∼75% SiO2). εNdT are characteristically negative (-12 to -18), with corresponding Nd TDM indicating sources with Paleoproterozoic mean crustal ages (2.0-2.5 Ga). The Guacuri and Santa Branca muscovite granites have the more negative εNdt, highest 87Sr/86Srt (0.714-0.717) and lowest 208Pb/206Pb and 207Pb/206Pb, consistent with an old metasedimentary source with low time-integrated Rb/Sr. However, a positive Nd-Sr isotope correlation is suggested by data from the other granites, and would be consistent with mixing between an older source predominant in the Mauá granite and a younger, high Rb/Sr source that is more abundant in the Lagoinha granite sample. The Ediacaran granites are coeval with profuse granite magmatism attributed to continental arc magmatism in northern Ribeira and Araçuaí belts. However, their evolved compositions with low mg# and dominantly peraluminous character are unlike those of magmatic arc granites, and they are more likely products of post-collisional magmatism or correspond to an inner belt of crust-derived granites.

Origin of depleted components in basalt related to the Hawaiian hot spot: Evidence from isotopic and incompatible element ratios

NASA Astrophysics Data System (ADS)

Frey, F. A.; Huang, S.; Blichert-Toft, J.; Regelous, M.; Boyet, M.

2005-02-01

The radiogenic isotopic ratios of Sr, Nd, Hf, and Pb in basaltic lavas associated with major hot spots, such as Hawaii, document the geochemical heterogeneity of their mantle source. What processes created such heterogeneity? For Hawaiian lavas there has been extensive discussion of geochemically enriched source components, but relatively little attention has been given to the origin of depleted source components, that is, components with the lowest 87Sr/86Sr and highest 143Nd/144Nd and 176Hf/177Hf. The surprisingly important role of a depleted component in the source of the incompatible element-enriched, rejuvenated-stage Hawaiian lavas is well known. A depleted component also contributed significantly to the ˜76-81 Ma lavas erupted at Detroit Seamount in the Emperor Seamount Chain. In both cases, major involvement of MORB-related depleted asthenosphere or lithosphere has been proposed. Detroit Seamount and rejuvenated-stage lavas, however, have important isotopic differences from most Pacific MORB. Specifically, they define trends to relatively unradiogenic Pb isotope ratios, and most Emperor Seamount lavas define a steep trend of 176Hf/177Hf versus 143Nd/144Nd. In addition, lavas from Detroit Seamount and recent rejuvenated-stage lavas have relatively high Ba/Th, a characteristic of lavas associated with the Hawaiian hot spot. It is possible that a depleted component, intrinsic to the hot spot, has contributed to these young and old lavas related to the Hawaiian hot spot. The persistence of such a component over 80 Myr is consistent with a long-lived source, i.e., a plume.

Evaluation of elemental status of ancient human bone samples from Northeastern Hungary dated to the 10th century AD by XRF

NASA Astrophysics Data System (ADS)

János, I.; Szathmáry, L.; Nádas, E.; Béni, A.; Dinya, Z.; Máthé, E.

2011-11-01

The present study is a multielemental analysis of bone samples belonging to skeletal individuals originating from two contemporaneous (10th century AD) cemeteries (Tiszavasvári Nagy-Gyepáros and Nagycserkesz-Nádasibokor sites) in Northeastern Hungary, using the XRF analytical technique. Emitted X-rays were detected in order to determine the elemental composition of bones and to appreciate the possible influence of the burial environment on the elemental content of the human skeletal remains. Lumbar vertebral bodies were used for analysis. Applying the ED(P)XRF technique concentration of the following elements were determined: P, Ca, K, Na, Mg, Al, Cl, Mn, Fe, Zn, Br and Sr. The results indicated post mortem mineral exchange between the burial environment (soil) and bones (e.g. the enhanced levels of Fe and Mn) and referred to diagenetic alteration processes during burials. However, other elements such as Zn, Sr and Br seemed to be accumulated during the past life. On the basis of statistical analysis, clear separation could not be observed between the two excavation sites in their bone elemental concentrations which denoted similar diagenetic influences, environmental conditions. The enhanced levels of Sr might be connected with the past dietary habits, especially consumption of plant food.

Interaction between different groundwaters in brittany catchments (france): characterizing multiple sources through Sr- and S isotope tracing

NASA Astrophysics Data System (ADS)

Negrel, Ph; Pauwels, H.

2003-04-01

Water resources in hard-rocks commonly involve different hydrogeological compartments such as overlying sediments, weathered rock, the weathered-fissured zone, and fractured bedrock. Streams, lakes and wetlands that drain such environments can drain groundwater, recharge groundwater, or do both. Groundwater resources in many countries are increasingly threatened by growing demand, wasteful use, and contamination. Surface water and shallow groundwater are particularly vulnerable to pollution, while deeper resources are more protected from contamination. Sr- and S-isotope data as well as major ions, from shallow and deep groundwater in three granite and Brioverian "schist" areas of the Armorican Massif (NW France) with intensive agriculture covering large parts are presented. The stable-isotope signatures of the waters plot close to the general meteoric-water line, reflecting a meteoric origin and the lack of significant evaporation or water-rock interaction. The water chemistry from the different catchments shows large variation in the major-element contents. Plotting Na, Mg, NO_3, K, SO_4 and Sr vs. Cl contents concentrations reflect agricultural input from hog and livestock farming and fertilizer applications, with local sewage-effluent influence, although some water samples are clearly unpolluted. The δ34S(SO_4) is controlled by several potential sources (atmospheric sulphate, pyrite-derived sulphates, fertilizer sulphates). Some δ18O and δ34S values are expected to increase through sulphate reduction, with higher effect on δ34S for the dissimilatory processes and on δ18O for assimilatory processes. The range in Sr contents in groundwater from different catchments agrees with previous work on groundwater sampled from granites in France. The Sr content is well correlated with Mg and both are related to agricultural practises. As in granite-gneiss watersheds in France, 87Sr/86Sr ratios range from 0.71265 to 0.72009. The relationship between 87Sr/86Sr and Mg/Sr ratios defines the different end-members (rain, agricultural practise, water-rock interaction) both in the three Brittany catchments and elsewhere in France such as the Margeride mountains (S Massif Central), the Hérault watershed (S France), the Morvan (SE Paris Basin), the Cantal (E Massif Central) and the Vosges massif (NE France). Sr-isotope tracing defines and identifies the relative signature of groundwater circulation in alterite and underlying weathered-fissured and fractured bedrock.

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.

Heavy metals and metalloids in egg contents and eggshells of passerine birds from Arizona

USGS Publications Warehouse

Mora, Miguel A.

2003-01-01

Concentrations of inorganic elements were determined in eggs of passerine birds including the endangered southwestern willow flycatcher (Empidonax traillii extimus) from four regions in Arizona. The main aim of the study was to determine the distribution of metals in egg contents and eggshells, with emphasis on the deposition of Sr in eggshells. Seventy eggs of 11 passerine species were collected at four nesting locations during 2000. Aluminum, Ba, Cr, Cu, Mn, Se, Sr, and Zn, were detected primarily in egg contents of all bird species. Arsenic, Ni, Pb, and V were detected primarily in eggshells. A proportion of most inorganic elements accumulated in the eggshell. Concentrations of Ba, Cu, Mn, Se, Sr, and Zn in egg contents and As, Ba, Cu, and V in eggshells of yellow-breasted chats (Icteria virens) were similar among locations. However, concentrations of Mn, Ni, Sr, and Zn in eggshells were significant different among locations. Except for Cu, Mn, Se, and Zn, concentrations of inorganic elements were 2–35 times greater in eggshells than in eggs. Most concentrations of metals and metalloids in eggs and eggshells of all the bird species were below levels known to affect reproduction or that have other deleterious effects. However, I found somewhat elevated concentrations of Sr in eggshells (highest mean=1505 μg/g dw, n=3) of yellow-breasted chats and willow flycatchers, and in egg contents of yellow warblers (Dendroica petechia) and song sparrows (Melospiza melodia). Whether current observed concentrations of Sr in eggshells are affecting nesting birds in Arizona remains to be determined. Strontium and other metals could be associated with lower hatching success in some areas. This study shows that a proportion of many inorganic elements accumulates in the eggshell and that the potential effects on the proper structure and functioning of the eggshell should not be ignored.

Effects of Ti and La Additions on the Microstructures and Mechanical Properties of B-Refined and Sr-Modified Al-11Si Alloys

NASA Astrophysics Data System (ADS)

Li, Chenlin; Pan, Ye; Lu, Tao; Jing, Lijun; Pi, Jinhong

2018-03-01

The effects of Ti and La additions on the microstructures and mechanical properties of B-refined and Sr-modified Al-11Si alloys were investigated in the present work. The interactions among Ti, La, B and Sr elements were discussed employing microstructure observation, thermal analysis and tensile test, respectively. It was found that the addition of 0.05 wt% B induces a transformation of eutectic Si from finely fibrous to coarsely plate-like morphology in the Al-11Si alloy with 0.02 wt%Sr modification, owing to the poisoning of IIT mechanism, and the eutectic Si grows only with TPRE mechanism. Both titanium and lanthanum can neutralize the co-poisoning effect between Sr and B in the Al-11Si alloy, but the neutralizing effect of La is dependent on the addition sequence. The combinative addition of La and B elements promotes the effective refinement of α-Al grains, but an inhomogeneous modification of eutectic Si phases is also observed, leading to a slightly decrease in the elongation.

Thermal effects on rare earth element and strontium isotope chemistry in single conodont elements

NASA Astrophysics Data System (ADS)

Armstrong, H. A.; Pearson, D. G.; Griselin, M.

2001-02-01

A low-blank, high sensitivity isotope dilution, ICP-MS analytical technique has been used to obtain REE abundance data from single conodont elements weighing as little as 5 μg. Sr isotopes can also be measured from the column eluants enabling Sr isotope ratios and REE abundance to be determined from the same dissolution. Results are comparable to published analyses comprising tens to hundreds of elements. To study the effects of thermal metamorphism on REE and strontium mobility in conodonts, samples were selected from a single bed adjacent to a basaltic dyke and from the internationally used colour alteration index (CAI) "standard set." Our analyses span the range of CAI 1 to 8. Homogeneous REE patterns, "bell-shaped" shale-normalised REE patterns are observed across the range of CAI 1 to 6 in both sample sets. This pattern is interpreted as the result of adsorption during early diagenesis and could reflect original seawater chemistry. Above CAI 6 REE patterns become less predictable and perturbations from the typical REE pattern are likely to be due to the onset of apatite recrystallisation. Samples outside the contact aureole of the dyke have a mean 87Sr/ 86Sr ratio of 0.708165, within the broad range of published mid-Carboniferous seawater values. Our analysis indicates conodonts up to CAI 6 record primary geochemical signals that may be a proxy for ancient seawater.

Isotopic and trace element geochemistry of the Seligdar magnesiocarbonatites (South Yakutia, Russia): Insights regarding the mantle evolution beneath the Aldan-Stanovoy shield

NASA Astrophysics Data System (ADS)

Doroshkevich, Anna G.; Prokopyev, Ilya R.; Izokh, Andrey E.; Klemd, Reiner; Ponomarchuk, Anton V.; Nikolaeva, Irina V.; Vladykin, Nikolay V.

2018-04-01

The Paleoproterozoic Seligdar magnesiocarbonatite intrusion of the Aldan-Stanovoy shield in Russia underwent extensive postmagmatic hydrothermal alteration and metamorphic events. This study comprises new isotopic (Sr, Nd, C and O) data, whole-rock major and trace element compositions and trace element characteristics of the major minerals to gain a better understanding of the source and the formation process of the carbonatites. The Seligdar carbonatites have high concentrations of P2O5 (up to 18 wt%) and low concentrations of Na, K, Sr and Ba. The chondrite-normalized REE patterns of these carbonatites display significant enrichments of LREE relative to HREE with an average La/Ybcn ratio of 95. Hydrothermal and metamorphic overprints changed the trace element characteristics of the carbonatites and their minerals. These alteration processes were responsible for Sr loss and the shifting of the Sr isotopic compositions towards more radiogenic values. The altered carbonatites are further characterized by distinct 18O- and 13C-enrichments compared to the primary igneous carbonatites. The alteration most likely resulted from both the percolation of crustal-derived hydrothermal fluids and subsequent metamorphic processes accompanied by interaction with limestone-derived CO2. The narrow range of negative εNd(T) values indicates that the Seligdar carbonatites are dominated by a homogenous enriched mantle source component that was separated from the depleted mantle during the Archean.

Timing, mantle source and origin of mafic dykes within the gravity anomaly belt of the Taihang-Da Hinggan gravity lineament, central North China Craton

NASA Astrophysics Data System (ADS)

Liu, Shen; Feng, Caixia; Feng, Guangying; Xu, Mengjing; Coulson, Ian M.; Guo, Xiaolei; Guo, Zhuang; Peng, Hao; Feng, Qiang

2017-09-01

Six mafic dyke swarms crop out in Hebei Province within the Taihang-Da Hinggan gravity lineament magmatic belt, China, and were sampled. Here, we present new zircon laser ablation-inductively coupled plasma-mass spectrometry U-Pb age, whole rock geochemical, and Sr-Nd-Pb-Hf isotopic data for the six areas where these mafic dykes occur. The mafic (dolerite) dykes formed between 131.6 ± 1.6 and 121.6 ± 1.1 Ma, and are enriched in the light rare earth elements (LREE), some of the large ion lithophile elements (LILE; e.g., Rb, Ba, and Sr) and Pb, and are depleted in Th, U, Nb and Ta; some samples are also depleted in Eu. The dykes have high initial 87Sr/86Sr ratios (0.7055-0.7057), negative εNd (t) values (-12.5 to -11.9), relatively constant Pb isotopic ratios ((206Pb/204Pb)i = 16.45-16.51, (207Pb/204Pb)i = 15.44-15.51, (208Pb/204Pb)i = 36.49-36.53), negative εHf (t) values (-18.2 to -15.1), and old Nd (TNdDM2; 2.17-2.47 Ga) and Hf (THfDM2; 2.28-2.33 Ga) model ages. These geochronological, geochemical, and isotopic data indicate that the dykes were derived from magmas generated by low to moderate degree partial melting (1.0%-10%) of an EM1-like garnet lherzolite mantle source; these magmas fractionated olivine, clinopyroxene, and hornblende prior to emplacement, and assimilated minimal amounts of crustal material. Several possible models have previously been proposed to explain the origin of Mesozoic magmatism in this region. However, here we propose a foundering model for these studied mafic dykes, involving the foundering of eclogite from thickened lower crust due to the collision between the Siberian Craton and the North China Craon.

Petrogenesis of the Baishan granite stock, Eastern Tianshan, NW China: Geodynamic setting and implications for potential mineralization

NASA Astrophysics Data System (ADS)

Cao, MingJian; Qin, KeZhang; Li, GuangMing; Evans, Noreen J.; McInnes, Brent I. A.; Lu, WeiWei; Deng, Gang

2017-11-01

Located in a region rich in Cu-Ni and Mo mineralization, the Baishan granitic stock is barren for reasons that remain enigmatic. Whole rock elemental and Sr-Nd isotope analysis, major element analysis of a number of minerals, and zircon trace element, U-Pb and Hf isotope analysis were undertaken in order to reveal the petrogenesis of the granites. All granites show typical I-type characteristics including metaluminous to slightly peraluminous, calc-alkaline signatures with a strong depletion of Nb, Ta, Ti and P, enrichment of light rare earth elements and large ion lithophile elements (e.g., Cs, Rb, Th, U, K). In addition, a strong depletion in Ti and P, highly fractionated light rare earth element patterns and less fractionated heavy rare earth element patterns, and negative correlations between SiO2 and TiO2, Al2O3, MgO, FeOT, P2O5, Zr and Hf suggest significant fractional crystallization of amphibole, apatite, zircon and Ti-bearing minerals. Whole rock Sr-Nd and zircon Hf isotopic compositions show wide variations with (87Sr/86Sr)i values of 0.70358 to 0.70505, εNd (t) of 3.8 to 7.2, and εHf (t) of 2.4 to 12.2 indicating derivation from partial melting of juvenile lower crust with obvious addition of ancient crust. Zircon U-Pb ages indicate a formation age of 292 Ma, significantly older than the ore-forming granite porphyry and slightly older than the regional mafic-ultramafic, A-type and diabase magmatism of Eastern Tianshan. The granite stocks were likely derived during heating of ascending asthenospheric mantle above a mantle plume in the Early Permian. Mineral chemistry, saturation thermometry, mineral species and whole rock Fe2O3/FeO ratios indicate a crystallization temperature of > 980 to 665 °C, pressure of 1.6 kbar and oxygen fugacity of ≤ NNO for the granite stock. Comparing the geochemistry, magma source and crystallization environment for the Early Permian barren granite and Late Triassic ore-related granite porphyry, the low ratios of Sr/Y and low (La/Yb)N, and reduced oxidation state (≤ NNO) in the granitic stock are signatures of infertility for the Early Permian granite. This study implies high Mo mineralization potential for granitic rocks with high Sr/Y, (La/Yb)N and highly oxidized conditions.

Mineral dissolution in the Cape Cod aquifer, Massachusetts, USA: I . Reaction stoichiometry and impact of accessory feldspar and glauconite on strontium isotopes, solute concentrations, and REY distribution

USGS Publications Warehouse

Bau, Michael; Alexander, Brian; Chesley, John T.; Dulski, Peter; Brantley, Susan L.

2004-01-01

To compare relative reaction rates of mineral dissolution in a mineralogically simple groundwater aquifer, we studied the controls on solute concentrations, Sr isotopes, and rare earth element and yttrium (REY) systematics in the Cape Cod aquifer. This aquifer comprises mostly carbonate-free Pleistocene sediments that are about 90% quartz with minor K-feldspar, plagioclase, glauconite, and Fe-oxides. Silica concentrations and pH in the groundwater increase systematically with increasing depth, while Sr isotopic ratios decrease. No clear relationship between 87Sr/86Sr and Sr concentration is observed. At all depths, the 87Sr/86Sr ratio of the groundwater is considerably lower than the Sr isotopic ratio of the bulk sediment or its K-feldspar component, but similar to that of a plagioclase-rich accessory separate obtained from the sediment. The Si-87Sr/86Sr-depth relationships are consistent with dissolution of accessory plagioclase. In addition, solutes such as Sr, Ca, and particularly K show concentration spikes superimposed on their respective general trends. The K-Sr-87Sr/86Sr systematics suggests that accessory glauconite is another major solute source to Cape Cod groundwater. Although the authigenic glauconite in the Cape Cod sediment is rich in Rb, it is low in in-grown radiogenic 87Sr because of its young Pleistocene age. The low 87Sr/86Sr ratios are consistent with equilibration of glauconite with seawater. The impact of glauconite is inferred to vary due to its variable abundance in the sediments. In the Cape Cod groundwater, the variation of REY concentrations with sampling depth resembles that of K and Rb, but differs from that of Ca and Sr. Shale-normalized REY patterns are light REY depleted, show negative Ce anomalies and super-chondritic Y/Ho ratios, but no Eu anomalies. REY input from feldspar, therefore, is insignificant compared to input from a K-Rb-bearing phase, inferred to be glauconite. These results emphasize that interpretation of groundwater chemistry, even in relatively simple aquifers, may be complicated by solute contributions from “exotic” accessory minerals such as glauconite. To detect such peculiarities, groundwater studies should combine the study of elemental concentration and isotopic composition of several solutes that show different geochemical behavior.

Tracing subduction zone fluid-rock interactions using trace element and Mg-Sr-Nd isotopes

NASA Astrophysics Data System (ADS)

Wang, Shui-Jiong; Teng, Fang-Zhen; Li, Shu-Guang; Zhang, Li-Fei; Du, Jin-Xue; He, Yong-Sheng; Niu, Yaoling

2017-10-01

Slab-derived fluids play a key role in mass transfer and elemental/isotopic exchanges in subduction zones. The exhumation of deeply subducted crust is achieved via a subduction channel where fluids from various sources are abundant, and thus the chemical/isotopic compositions of these rocks could have been modified by subduction-zone fluid-rock interactions. Here, we investigate the Mg isotopic systematics of eclogites from southwestern Tianshan, in conjunction with major/trace element and Sr-Nd isotopes, to characterize the source and nature of fluids and to decipher how fluid-rock interactions in subduction channel might influence the Mg isotopic systematics of exhumed eclogites. The eclogites have high LILEs (especially Ba) and Pb, high initial 87Sr/86Sr (up to 0.7117; higher than that of coeval seawater), and varying Ni and Co (mostly lower than those of oceanic basalts), suggesting that these eclogites have interacted with metamorphic fluids mainly released from subducted sediments, with minor contributions from altered oceanic crust or altered abyssal peridotites. The positive correlation between 87Sr/86Sr and Pb* (an index of Pb enrichment; Pb* = 2*PbN/[CeN + PrN]), and the decoupling relationships and bidirectional patterns in 87Sr/86Sr-Rb/Sr, Pb*-Rb/Sr and Pb*-Ba/Pb spaces imply the presence of two compositionally different components for the fluids: one enriched in LILEs, and the other enriched in Pb and 87Sr/86Sr. The systematically heavier Mg isotopic compositions (δ26Mg = - 0.37 to + 0.26) relative to oceanic basalts (- 0.25 ± 0.07) and the roughly negative correlation of δ26Mg with MgO for the southwestern Tianshan eclogites, cannot be explained by inheritance of Mg isotopic signatures from ancient seafloor alteration or prograde metamorphism. Instead, the signatures are most likely produced by fluid-rock interactions during the exhumation of eclogites. The high Rb/Sr and Ba/Pb but low Pb* eclogites generally have high bulk-rock δ26Mg values, whereas high Pb* and 87Sr/86Sr eclogites have mantle-like δ26Mg values, suggesting that the two fluid components have diverse influences on the Mg isotopic systematics of these eclogites. The LILE-rich fluid component, possibly derived from mica-group minerals, contains a considerable amount of isotopically heavy Mg that has shifted the δ26Mg of the eclogites towards higher values. By contrast, the 87Sr/86Sr- and Pb-rich fluid component, most likely released from epidote-group minerals in metasediments, has little Mg so as not to modify the Mg isotopic composition of the eclogites. In addition, the influence of talc-derived fluid might be evident in a very few eclogites that have low Rb/Sr and Ba/Pb but slightly heavier Mg isotopic compositions. These findings represent an important step toward a broad understanding of the Mg isotope geochemistry in subduction zones, and contributing to understanding why island arc basalts have averagely heavier Mg isotopic compositions than the normal mantle.

77 FR 31045 - Order Prohibiting Involvement in NRC-Licensed Activities; In the Matter of Jaime Sánchez

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-24

... NUCLEAR REGULATORY COMMISSION [NRC-2012-0115; IA-11-036] Order Prohibiting Involvement in NRC-Licensed Activities; In the Matter of Jaime S[aacute]nchez I Jaime S[aacute]nchez (Mr. S[aacute]nchez) is President of S&R Engineering (S&R, licensee) in San Juan, Puerto Rico. S&R held License No. 52-30913-01...

Coal fly ash interaction with environmental fluids: Geochemical and strontium isotope results from combined column and batch leaching experiments

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

Brubaker, Tonya M; Stewart, Brian W; Capo, Rosemary C

2013-05-01

The major element and Sr isotope systematics and geochemistry of coal fly ash and its interactions with environmental waters were investigated using laboratory flow-through column leaching experiments (sodium carbonate, acetic acid, nitric acid) and sequential batch leaching experiments (water, acetic acid, hydrochloric acid). Column leaching of Class F fly ash samples shows rapid release of most major elements early in the leaching procedure, suggesting an association of these elements with soluble and surface bound phases. Delayed release of certain elements (e.g., Al, Fe, Si) signals gradual dissolution of more resistant silicate or glass phases as leaching continues. Strontium isotope resultsmore » from both column and batch leaching experiments show a marked increase in {sup 87}Sr/{sup 86}Sr ratio with continued leaching, yielding a total range of values from 0.7107 to 0.7138. For comparison, the isotopic composition of fluid output from a fly ash impoundment in West Virginia falls in a narrow range around 0.7124. The experimental data suggest the presence of a more resistant, highly radiogenic silicate phase that survives the combustion process and is leached after the more soluble minerals are removed. Strontium isotopic homogenization of minerals in coal does not always occur during the combustion process, despite the high temperatures encountered in the boiler. Early-released Sr tends to be isotopically uniform; thus the Sr isotopic composition of fly ash could be distinguishable from other sources and is a useful tool for quantifying the possible contribution of fly ash leaching to the total dissolved load in natural surface and ground waters.« less

Determination of element/Ca ratios in foraminifera and corals using cold- and hot-plasma techniques in inductively coupled plasma sector field mass spectrometry

NASA Astrophysics Data System (ADS)

Lo, Li; Shen, Chuan-Chou; Lu, Chia-Jung; Chen, Yi-Chi; Chang, Ching-Chih; Wei, Kuo-Yen; Qu, Dingchuang; Gagan, Michael K.

2014-02-01

We have developed a rapid and precise procedure for measuring multiple elements in foraminifera and corals by inductively coupled plasma sector field mass spectrometry (ICP-SF-MS) with both cold- [800 W radio frequency (RF) power] and hot- (1200 W RF power) plasma techniques. Our quality control program includes careful subsampling protocols, contamination-free workbench spaces, and refined plastic-ware cleaning process. Element/Ca ratios are calculated directly from ion beam intensities of 24Mg, 27Al, 43Ca, 55Mn, 57Fe, 86Sr, and 138Ba, using a standard bracketing method. A routine measurement time is 3-5 min per dissolved sample. The matrix effects of nitric acid, and Ca and Sr levels, are carefully quantified and overcome. There is no significant difference between data determined by cold- and hot-plasma methods, but the techniques have different advantages. The cold-plasma technique offers a more stable plasma condition and better reproducibility for ppm-level elements. Long-term 2-sigma relative standard deviations (2-RSD) for repeat measurements of an in-house coral standard are 0.32% for Mg/Ca and 0.43% for Sr/Ca by cold-plasma ICP-SF-MS, and 0.69% for Mg/Ca and 0.51% for Sr/Ca by hot-plasma ICP-SF-MS. The higher sensitivity and enhanced measurement precision of the hot-plasma procedure yields 2-RSD precision for μmol/mol trace elements of 0.60% (Mg/Ca), 9.9% (Al/Ca), 0.68% (Mn/Ca), 2.7% (Fe/Ca), 0.50% (Sr/Ca), and 0.84% (Ba/Ca) for an in-house foraminiferal standard. Our refined ICP-SF-MS technique, which has the advantages of small sample size (2-4 μg carbonate consumed) and fast sample throughput (5-8 samples/hour), should open the way to the production of high precision and high resolution geochemical records for natural carbonate materials.

Transcriptome analyses reveal SR45 to be a neutral splicing regulator and a suppressor of innate immunity in Arabidopsis thaliana.

PubMed

Zhang, Xiao-Ning; Shi, Yifei; Powers, Jordan J; Gowda, Nikhil B; Zhang, Chong; Ibrahim, Heba M M; Ball, Hannah B; Chen, Samuel L; Lu, Hua; Mount, Stephen M

2017-10-11

Regulation of pre-mRNA splicing diversifies protein products and affects many biological processes. Arabidopsis thaliana Serine/Arginine-rich 45 (SR45), regulates pre-mRNA splicing by interacting with other regulatory proteins and spliceosomal subunits. Although SR45 has orthologs in diverse eukaryotes, including human RNPS1, the sr45-1 null mutant is viable. Narrow flower petals and reduced seed formation suggest that SR45 regulates genes involved in diverse processes, including reproduction. To understand how SR45 is involved in the regulation of reproductive processes, we studied mRNA from the wild-type and sr45-1 inflorescences using RNA-seq, and identified SR45-bound RNAs by immunoprecipitation. Using a variety of bioinformatics tools, we identified a total of 358 SR45 differentially regulated (SDR) genes, 542 SR45-dependent alternative splicing (SAS) events, and 1812 SR45-associated RNAs (SARs). There is little overlap between SDR genes and SAS genes, and neither set of genes is enriched for flower or seed development. However, transcripts from reproductive process genes are significantly overrepresented in SARs. In exploring the fate of SARs, we found that a total of 81 SARs are subject to alternative splicing, while 14 of them are known Nonsense-Mediated Decay (NMD) targets. Motifs related to GGNGG are enriched both in SARs and near different types of SAS events, suggesting that SR45 recognizes this motif directly. Genes involved in plant defense are significantly over-represented among genes whose expression is suppressed by SR45, and sr45-1 plants do indeed show enhanced immunity. We find that SR45 is a suppressor of innate immunity. We find that a single motif (GGNGG) is highly enriched in both RNAs bound by SR45 and in sequences near SR45- dependent alternative splicing events in inflorescence tissue. We find that the alternative splicing events regulated by SR45 are enriched for this motif whether the effect of SR45 is activation or repression of the particular event. Thus, our data suggests that SR45 acts to control splice site choice in a way that defies simple categorization as an activator or repressor of splicing.

Source characteristics and tectonic setting of mafic-ultramafic intrusions in North Xinjiang, NW China: Insights from the petrology and geochemistry of the Lubei mafic-ultramafic intrusion

NASA Astrophysics Data System (ADS)

Chen, Bao-Yun; Yu, Jin-Jie; Liu, Shuai-Jie

2018-05-01

The newly discovered Lubei sulfide-bearing mafic-ultramafic intrusion forms the western extension of the Huangshan-Jin'erquan mafic-ultramafic intrusion belt in East Tianshan, NW China. The Lubei intrusion comprises hornblende peridotite, lherzolite, and harzburgite in its southern portion, gabbro in its middle portion, and hornblende gabbro in its northern portion. Intrusive relationships indicate that three magma pulses were involved in the formation of the intrusion, and that they were likely evolved from a common primitive magma. Estimated compositions of the Lubei primitive magma are similar to those of island arc calc-alkaline basalt except for the low Na2O and CaO contents of the Lubei primitive magma. This paper reports on the mineral compositions, whole-rock major and trace element contents, and Rb-Sr and Sm-Nd isotopic compositions of the Lubei intrusion, and a zircon LA-MC-ICP-MS U-Pb age for hornblende gabbro. The Lubei intrusion is characterized by enrichment in large-ion lithophile elements, depletion in high-field-strength elements, and marked negative Nb and Ta anomalies, with enrichment in chondrite-normalized light rare earth elements. It exhibits low (87Sr/86Sr)i ratios of 0.70333-0.70636 and low (143Nd/144Nd)i ratios of 0.51214-0.51260, with positive εNd values of +4.01 to +6.33. LA-ICP-MS U-Pb zircon ages yielded a weighted-mean age of 287.9 ± 1.6 Ma for the Lubei intrusion. Contemporaneous mafic-ultramafic intrusions in different tectonic domains in North Xinjiang show similar geological and geochemical signatures to the Lubei intrusion, suggesting a source region of metasomatized mantle previously modified by hydrous fluids from the slab subducted beneath the North Xinjiang region in the early Permian. Metasomatism of the mantle was dominated by hydrous fluids and was related to subduction of the Paleo-Asian oceanic lithosphere during the Paleozoic. Sr-Nd-Pb isotopic compositions suggest that the mantle source was a mixture of depleted mid-ocean-ridge-basalt mantle and enriched-mantle I components. The Permian mafic-ultramafic intrusions in North Xinjiang were formed from tholeiitic basaltic magmas derived from decompression partial melting of the metasomatized mantle in a post-collision extensional tectonic setting. The tholeiitic basaltic magmas are equivalent to the voluminous underplated basaltic magmas that formed during vertical crustal growth of the Central Asian Orogenic Belt in the later Paleozoic.

Minor and potentially toxic trace elements in milk and blood serum of dairy donkeys.

PubMed

Fantuz, F; Ferraro, S; Todini, L; Piloni, R; Mariani, P; Malissiova, E; Salimei, E

2015-08-01

The aim of this trial was to study the concentration of Ti, V, As, Rb, Sr, Mo, Cd, Cs, and Pb in donkey milk and blood serum. One hundred twelve individual milk and blood serum samples were collected from 16 lactating donkeys (Martina-Franca-derived population; 6 to 12 yr old; 3 to 7 parities; average live weight 205.4kg; 32 to 58 d after foaling at the beginning of the trial) during a 3-mo-long experiment. The samples were analyzed for the aforementioned elements by inductively coupled plasma-mass spectrometry. Feedstuff and drinking water were also analyzed for the investigated elements. Data were processed by ANOVA for repeated measures. Average milk concentrations (±SD) of Ti, Rb, Sr, Mo, Cs, and Pb were 77.3 (±7.7), 339.1 (±82.1), 881.7 (±270.4), 4.5 (±1.6), 0.49 (±0.09), and 3.2 (±2.7) μg/L, respectively. More than 80% of samples were below the limit of detection for V, As, and Cd in milk and for Cd, and Pb in blood serum. The lower bound calculated for milk V, As, and Cd was 0.03μg/L for the 3 elements, the upper bound was calculated at 0.23, 0.10, and 0.31μg/L and the maximum value was observed at 0.54, 0.15, and 0.51μg/L, respectively. The average milk concentrations of Ti, Rb, Sr, Mo, and Cs were 600, 458, 346, 16, and 294%, respectively, than those of blood serum. Yet, Cs concentrations were in the same order of magnitude in milk and serum. Moderate to strong positive and significant correlation coefficients were observed between milk and blood serum concentrations for Ti, Rb, Sr, and Cs. The effect of the stage of lactation was significant for all the investigated elements in milk and blood serum, but most of the elements showed only small changes or inconsistent trends, and only the concentrations of Rb and Sr showed decreasing trends both in milk and blood serum. The relationship between milk and blood serum element concentrations indicates that the mammary gland plays a role in determining the milk concentrations of Mo, Ti, Rb, Sr, Mo, and Cs. In the current experimental conditions, in agreement with the low levels in drinking water and feedstuff, donkey milk concentration of potentially toxic elements was very low and did not raise health concerns for human consumption. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The geochemical and Sr-Nd-Pb-He isotopic characterization of the mantle source of Rungwe Volcanic Province: comparison with the Afar mantle domain

NASA Astrophysics Data System (ADS)

Castillo, P. R.; Hilton, D. R.; Halldorsson, S. A.; Wang, R.

2012-12-01

The ultimate source of heat and magmatism associated with continental rifting in the East African Rift System (EARS) is generally viewed to be the African Superplume, but there is continuing debate on the surface expression of this large anomalous feature, which originates in the lower mantle. Previous studies have demonstrated an insignificant role for crustal contamination thereby identifying a single mantle plume signature in Quaternary basalts from the Main Ethiopian Rift in the northern EARS. This is designated to be the Afar plume and is characterized by, e.g., 3He/4He >15 RA, 206Pb/204Pb = 19.5 and 87Sr/86Sr = 0.7035 [Rooney et al., J. Pet. 53, 2012]. In contrast, the signature of plume(s) in the southern EARS is less constrained. Rogers et al. [EPSL 176, 2000] proposed a plume in the sub-lithospheric Kenyan mantle with characteristically lower 43Nd/144Nd than the Afar plume whereas Furman [JAES 48, 2007] advocated a high μ [HIMU] plume based primarily on the high 206Pb/204Pb ratios of lavas in all areas within and south of the Turkana Depression: both models assume a 3He/4He lower than the Afar plume. Here we report the trace element and Sr-Nd-Pb isotopic composition of basaltic lavas from the Rungwe Volcanic Province (RVP) in the southern extreme of the Western Rift previously identified as a high 3He/4He locality (~15 RA; [Hilton et al., GRL 38, 2011]). Trace element analyses are within the previously reported range of lava compositions that include a relatively large lithospheric component. More importantly, we identify correlations among incompatible trace element and isotopic ratios (e.g., 3He/4He vs 206Pb/204Pb, Rb/Sr, Nb/Ta; 87Sr/86Sr vs 208Pb/204Pb). Our new results suggest the presence of a distinct, high 3He/4He mantle source beneath RVP that is more radiogenic (e.g., 206Pb/204Pb up to ~19.8; 87Sr/86Sr up to 0.7055) than the Afar mantle plume. There is also very little or no HIMU signature in RPV basalts based on their high Sr and low Nd isotopic ratios.

Investigating the hydrological significance of stalagmite geochemistry (Mg, Sr) using Sr isotope and particulate element records across the Late Glacial-to-Holocene transition

NASA Astrophysics Data System (ADS)

Belli, R.; Borsato, A.; Frisia, S.; Drysdale, R.; Maas, R.; Greig, A.

2017-02-01

The trace element and Sr isotope records in two coeval stalagmites characterized by different growth rates and flow regimes at Savi cave (Grotta Savi, NE Italy) reveal different sources and incorporation mechanisms for Mg and Sr. Mg is sourced primarily from dissolved cave host rock while particulate Mg derived from soil plays a subordinate role. The presence of particulate-borne Mg is inferred from the co-variation of Mg and particle-associated elements (Th, Al and Mn) which are preferentially concentrated in open columnar calcite layers. Variation in Mg concentrations corrected for particle-influenced components, the Mgc parameter, is controlled by water-rock interaction, with higher and lower Mgc during dry and wet phases, respectively. This is thought to reflect incongruent dissolution of Mg-rich phases. Correction of Sr concentrations for contributions from airborne exogenic Sr, based on 87Sr/86Sr ratios, yields the bedrock-only contribution (Src). Src variation in stalagmite calcite is influenced by speleothem growth rate and by variation of the calcite-water Sr partitioning in wet and dry phases, and only to a minor extent by incongruent dissolution of Mg-rich phases. Concentration profiles for Mgc and Srcg (corrected for growth rate effects) show inverse correlations and are inferred to show hydrological significance which is captured in a hydrological index, HI. We suggest HI provides robust information on water-rock interaction related to hydrological changes and can be utilized in both wet and semi-arid environments, provided the corrections for soil Mg and exogenic Sr can be applied with confidence. Application of the HI index allows correction of Grotta Savi oxygen isotope data, to yield a δ18Oc time series that shows when changes in moisture sources and atmospheric reorganization, or changes in moisture amount, were significant. This is especially evident during the Younger Dryas (YD). The Savi record supports the concept of a two-phase YD, marked by an increase of moisture and stronger impact of Adriatic and Mediterranean Sea influences over the northern Adriatic region from 12.3 ka onwards. Then, a large-scale atmospheric reorganization and gradual northward shift of the Polar Front caused a progressive reduction of sea influence over the region from 12.1 ka, supporting the concept of a hemispheric change.

Mineral elements and essential trace elements in blood of seals of the North Sea measured by total-reflection X-ray fluorescence analysis

NASA Astrophysics Data System (ADS)

Griesel, S.; Mundry, R.; Kakuschke, A.; Fonfara, S.; Siebert, U.; Prange, A.

2006-11-01

Mineral and essential trace elements are involved in numerous physiological processes in mammals. Often, diseases are associated with an imbalance of the electrolyte homeostasis. In this study, the concentrations of mineral elements (P, S, K, Ca) and essential trace elements (Fe, Cu, Zn, Se, Rb, Sr) in whole blood of harbor seals ( Phoca vitulina) were determined using total-reflection X-ray fluorescence spectrometry (TXRF). Samples from 81 free-ranging harbor seals from the North Sea and two captive seals were collected during 2003-2005. Reference ranges and element correlations for health status determination were derived for P, S, K, Ca, Fe, Cu, and Zn level in whole blood. Grouping the seals by age, gender and sample location the concentration levels of the elements were compared. The blood from two captive seals with signs of diseases and four free-ranging seals showed reduced element levels of P, S, and Ca and differences in element correlation of electrolytes were ascertained. Thus, simultaneous measurements of several elements in only 500 μL volumes of whole blood provide the possibility to obtain information on both, the electrolyte balance and the hydration status of the seals. The method could therefore serve as an additional biomonitoring tool for the health assessment.

Studies on uptake and retention of trace elements by medicinal plants in the environs of Hassan of South India

NASA Astrophysics Data System (ADS)

Jagadeesha, B. G.; Narayana, Y.; Sudarshan, M.; Banerjee, Shamayita

2018-03-01

The transfer factors of trace elements from soil to medicinal plants were determined in the region of Hassan district of south India. The trace element concentration was determined using the Energy Dispersive X-ray Fluorescence (ED-XRF) spectrometer. The transfer factors were found in the order Rb > Sr > Ca > K > Zn > Cu > Mn. The transfer factors were found to be high, for most of the plants. The concentration of Rb and Sr was found to be high in medicinal plants, which can be attributed to the mineralogy of the region and plant morphology.

Petrogenesis of mid-Miocene rhyolites from the Idaho-Oregon-Nevada region, USA: Implications from feldspar Sr and Pb isotope data

NASA Astrophysics Data System (ADS)

Wypych, A.; Hart, W. K.

2012-12-01

The Idaho-Oregon-Nevada (ION) region provides an excellent natural laboratory for studying the complex processes that form continental crust. During the Oligocene-Miocene, the ION region underwent widespread extension and volcanism with bimodal (silicic and mafic) volcanism dominating the mid-Miocene [1]. This bimodal volcanism is temporally related to the main Columbia River flood basalt activity to the north, and initiated with mafic eruptions at ~17 Ma, followed closely by silicic magmatism at ~16.5 Ma. This intimate link between mafic and silicic activity continued until ~13 Ma. The ION region is situated on a boundary between Proterozoic cratonic lithosphere to the east and Mesozoic accreted terrains to the west as defined by Sr and Nd isotopic compositions. In this region, however, the boundary is not sharp and distinctive, but rather forms a heterogeneous "transitional zone" between the two lithospheric domains. Another feature adding to the complexity of this region is the fact that it lies at the junction of two major volcanic trends: the Snake River Plain- Yellowstone (SRP-Y) progressing in time and space to the northeast and the High Lava Plains - Newberry (HPL-N) progressing to the northwest. The ION region volcanism as well as the SRP-Y and HLP-N volcanic trends is caused by mantle upwelling behind the subducting Juan de Fuca slab, voluminous mafic magma injections into the crust, melting of spatially, temporally, and compositionally heterogeneous crust, and mixing of the primitive and more evolved products [1,2,3]. An ongoing petrographic, major and trace element and Sr-Nd-Pb-Hf isotope investigation of 24 pairs of glass separates and whole rock samples from five ION silicic centers representing a west (off-craton) to east (on-craton) transect across this zone of transitional lithosphere provides evidence of open system processes involved in the production of the silicic material as well as spatial, temporal and compositional diversity within and between the silicic centers [4]. The samples demonstrate involvement of fractional crystallization of less evolved mafic material along with assimilation of partial crustal melts, however the degree of involvement of each process remains difficult to quantify, as do the contributions from mantle and crustal reservoirs. To further investigate these issues, we here present petrological, major and trace element, along with lead and strontium isotopic examination of feldspar crystals from three selected silicic centers: 1) westernmost, off-craton, 2) central region of transitional lithosphere, and 3) eastern transition zone to on-craton. The textural evidence for open system behavior is only partially supported by bulk feldspar Pb and Sr isotopic compositions where the differences between whole rock, glass and crystal separate aliquots of the same eruptive units are a maximum of 0.3 in 208Pb/204Pb, 0.2 in 206Pb/204Pb and 0.002 in 87Sr/86Sr. Models combining these results with the spatial availability of geochemically distinct magma source reservoirs will be discussed. [1] Brueseke et al. (2008) Bull. Volc. 70, 343-360. [2] Nash et al. (2006) Earth Plant. Sci. Lett. 247, 143-156. [3] Christiansen and McCurry (2008) Bull. Volc., 70, 251-267. [4] Wypych and Hart (2011) Min. Magazine, 75 (3), 2186.

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.

Origin of peralkaline granites of Saudi Arabia

NASA Astrophysics Data System (ADS)

Radain, A. A. M.; Fyfe, W. S.; Kerrich, R.

1982-01-01

Small volumes of peralkaline granites were generated as the final phase of a Pan African calc-alkaline igneous event which built the Arabian Peninsula. The peralkaline granites are closely associated with trends or sutures related to ophiolites. Peralkaline rocks are chemically heterogeneous, with anomalous abundances of Zr (average 2,150 ppm±2,600 1σ), Y (200±190), and Nb (105±100), representing up to ten-fold enrichments of these elements relative to abundances in calc alkaline granite counterparts. Large enrichments of some rare earth elements and fluorine are also present. The peralkaline granites have scattered whole rock 18O values, averaging 8.7±0.6% in the Hadb Aldyaheen Complex and 10.7±1% in the Jabal Sayid Complex. Quartz-albite fractionations of 0.5 to 1.5% signify that the heavier whole rock δ-values probably represent the oxygen isotope composition of the peralkaline magma. Small variable enrichments of 18O, in conjunction with slightly elevated 87Sr/86Sr initial ratios relative to broadly contemporaneous calc alkaline granites, are both suggestive of a small degree of involvement of crustal, or crustal derived material in the peralkaline magmas. It is proposed that the peculiar magma genesis is associated with a relaxation event which followed continental collision and underthrusting of salt rich sediments.

Distribution behavior of uranium, neptunium, rare-earth elements ( Y, La, Ce, Nd, Sm, Eu, Gd) and alkaline-earth metals (Sr,Ba) between molten LiClKCI eutectic salt and liquid cadmium or bismuth

NASA Astrophysics Data System (ADS)

Kurata, M.; Sakamura, Y.; Hijikata, T.; Kinoshita, K.

1995-12-01

Distribution coefficients of uranium neptunium, eight rare-earth elements (Y, La, Ce, Pr, Nd, Sm, Eu and Gd) and two alkaline-earth metals (Sr and Ba) between molten LiCl-KCI eutectic salt and either liquid cadmium or bismuth were measured at 773 K. Separation factors of trivalent rare-earth elements to uranium or neptunium in the LiCl-KCl/Bi system were by one or two orders of magnitude larger than those in the LiCl-KCl/Cd system. On the contrary, the separation factors of alkaline-earth metals and divalent rare-earth elements to trivalent rare-earth elements were by one or two orders of magnitude smaller in the LiCl-KCl/Bi system.

Multiple enrichment of the Carpathian-Pannonian mantle: Pb-Sr-Nd isotope and trace element constraints

NASA Astrophysics Data System (ADS)

Rosenbaum, Jeffrey M.; Wilson, Marjorie; Downes, Hilary

1997-07-01

Pb isotope compositions of acid-leached clinopyroxene and amphibole mineral separates from spinel peridotite mantle xenoliths entrained in Tertiary-Quaternary alkali basalts from the Carpathian-Pannonian Region of eastern Europe provide important constraints on the processes of metasomatic enrichment of the mantle lithosphere in an extensional tectonic setting associated with recent subduction. Principal component analysis of Pb-Sr-Nd isotope and rare earth element compositions of the pyroxenes is used to identify the geochemical characteristics of the original lithospheric mantle protolith and a spectrum of infiltrating metasomatic agents including subduction-related aqueous fluids and silicate melts derived from a subduction-modified mantle wedge which contains a St. Helena-type (HIMU) plume component. The mantle protolith is highly depleted relative to mid-ocean ridge basalt-source mantle with Pb-Nd-Sr isotope compositions consistent with an ancient depletion event. Silicate melt infiltration into the protolith accounts for the primary variance in the Pb-Sr-Nd isotope compositions of the xenoliths and has locally generated metasomatic amphibole. Infiltration of aqueous fluids has introduced radiogenic Pb and Sr without significantly perturbing the rare earth element signature of the protolith. The Pb isotope compositions of the fluid-modified xenoliths suggest that they reacted with aqueous fluids released from a subduction zone which had equilibrated with sediment derived from an ancient basement terrain. We propose a model for mantle lithosphere evolution consistent with available textural and geochemical data for the xenolith population. The Pb-Sr-Nd isotope compositions of both alkaline mafic magmas and rare, subduction-related, calc-alkaline basaltic andesites from the region provide important constraints for the nature of the asthenospheric mantle wedge and confirm the presence of a HIMU plume component. These silicate melts contribute to the metasomatism of the mantle lithosphere rather than being derived therefrom.

Dissolved Strontium and Barium in Fresh and Saltwater: a 2-year Study in the Calcasieu River to the Gulf of Mexico

NASA Astrophysics Data System (ADS)

He, S.; Xu, Y. J.

2016-02-01

Strontium and barium to calcium ratios are often used as proxies for tracking animal movement across salinity gradients. As sea level rise continues, many estuarine rivers face saltwater intrusion, which may cause changes in mobility and distribution of these metals upstream. Despite intensive research on metal adsorption and desorption in marine systems, knowledge of the spatiotemporal distribution of these elements along estuarine rivers is still limited. In this study, we conducted an intensive monitoring of Sr and Ba dynamics along an 88-km long estuary, the Calcasieu River, which has been strongly affected by saltwater intrusion. Over the period from May 2013 to July 2015, we collected monthly water samples and performed in-situ water quality measurements at six sites from the upstream to the river mouth. Water samples were analyzed for dissolved Sr, Ba, and Ca concentrations. In-situ measurements of salinity, pH, water temperature, dissolved oxygen concentration, and specific conductance were taken. Our preliminary data showed that the Sr and Ca concentrations and the Sr/Ca ratio all increased significantly with decreasing distance to the Gulf of Mexico, while the Ba/Ca ratio decreased with decreasing distance to the Gulf. The spatial variation in Ba concentration was marginal. The Sr and Ca concentrations and ratios were positively related to salinity, while Ba/Ca was negatively related to salinity. All the elemental concentrations and ratios had considerable seasonal and interannual variations. There were significant differences among sampling months for all the elemental concentrations and ratios (p<0.05), and there were significant differences among sampling years for the Sr and Ca concentrations and the Ba/Ca ratio (p<0.05).

Simulating real-world field-based petrologic research in a field course: Incorporation of portable X-ray fluorescence spectrometry in the Iceland Volcanology Field Camp

NASA Astrophysics Data System (ADS)

Jordan, B.

2016-12-01

Field-based petrologic research projects often involve multiple field seasons, with geochemical analysis of samples collected in one season informing aspects of subsequent field seasons. To simulate this approach in the Iceland Volcanology Field Camp (South Dakota School of Mines & Technology) a portable X-ray fluorescence spectrometer (pXRF) was employed to provide "laboratory analyses" in support of a course mapping project. The project was conducted in the Árnes central volcano in the Neogene plateau lava succession in the West Fjords of northwestern Iceland. The field area has a wide compositional spectrum from basalt to rhyolite, with abundant intermediates. The pXRF is particularly helpful in the study of these kinds of rocks in Iceland because lithologies can be quite similar across a wide range of compositions (often lacking diagnostic macroscopic phenocryst assemblages, and having similar groundmass characteristics). A Bruker Tracer III-SD pXRF was utilized, operating at 40 KeV and 11.2 μA with no filter. Analyses were conducted at basecamp in the evenings on relatively flat fresh surfaces, with three 30 s analyses of different spots for each sample. A basic empirical calibration was generated with six aphyric samples previously analyzed by laboratory XRF. Light elements Na, Mg, and Al were not determined directly, but were estimated based on linear or polynomial correlations with other elements or elemental ratios (K, Ca, and Sr/Y respectively) determined from a previously obtained laboratory XRF data set for this central volcano. The resulting chemical analyses (normalized to sum to 100%) provided full major and minor element compositions to be used for classification, and several trace elements (V, Sr, Y, Zr) that could potentially distinguish different lavas of similar major element composition. The approach is coarse, and has pitfalls particularly regarding porphyritic rocks, but serves the objectives of the field camp project.

Mid-Miocene two-mica granites in the Malashan gneiss dome, south Tibet: Geochemical characteristics and formation mechanism

NASA Astrophysics Data System (ADS)

Gao, L.; Zeng, L.

2011-12-01

Knowledge of the timing of formation and geochemical nature of the Cenozoic granites along the High Himalaya as well as the Tethyan Himalaya is essential to test or formulate models that link high-grade metamorphism, crustal anatexis, and tectonic transition during the evolution of the Himalayan orogen. The Malashan gneiss dome, one of the prominent domes within the Tethyan Himalaya, consists of pelitic schists, calc-silicate metamorphic rocks, and at least two generations of granites. Two mica granites(TMG) occur as large plutons in Cuobu and Malashan, whereas a small leucogranite pluton occurs at the western side of the Paiku Lake. Two-mica granites from the Cuobu and the Malashan share similar characteristics in mineral composition, major and trace element geochemistry and isotope(Sr and Nd) compositions. New LA-ICP-MS zircon U/Pb analyses yielded that the Cuobu and the Malashan TMG formed at 17.6±0.1 Ma and 16.9±0.1 Ma, respectively. Both suits of granites are characterized by:(1)high SiO2(>71.3wt%), Al2O3(>14.8wt%), and relatively high CaO(>1.5wt%); (2)high A/CNK(>1.0) and K/Na ratios; (3)relatively high Sr(>146ppm), low Rb(<228ppm) and Rb/Sr ratios(<1.3); (4) enriched in LREE, depleted in HREE, as well as no or weakly negative Eu anomalies(Eu*=0.7~0.9); (5) as compared to leucogranites of similar ages in other Northern Himalayan Gneiss Domes, lower initial 87Sr/86Sr ratios (0.7390~0.7484) and similarly unradiogenic Nd isotope compositions (ɛNd(t)=-13.7~-14.4). Correlations between Ba and Rb/Sr ratios and between Rb/Sr and initial 87Sr/86Sr ratios imply that these two-mica granites were derived from muscovite H2O-fluxed melting of metasedimentary rocks at T=700-780oC. Such a reaction could be represented by 9Muscovite + 15Plagioclase + 7Quartz + xH2O = 31Melt, in which enhances the involvement of plagioclase, but suppresses the biotite due to relatively low temperature and the presence of water. This reaction not only produces granitic melts with low Rb/Sr ratios, relatively high CaO and weak to no Eu anomalies, but also leads to lower initial 87Sr/86Sr ratios than their potential source rocks.

Isotopic evolution of Mauna Loa Volcano: A view from the submarine southwest rift zone

NASA Astrophysics Data System (ADS)

Kurz, Mark D.; Kenna, T. C.; Kammer, D. P.; Rhodes, J. Michael; Garcia, Michael O.

New isotopic and trace element measurements on lavas from the submarine southwest rift zone (SWR) of Mauna Loa continue the temporal trends of subaerial Mauna Loa flows, extending the known compositional range for this volcano, and suggesting that many of the SWR lavas are older than any exposed on land. He and Nd isotopic compositions are similar to those in the oldest subaerial Mauna Loa lavas (Kahuku and Ninole Basalts), while 87Sr/86Sr ratios are slightly lower (as low as .7036) and Pb isotopes are higher (206Pb'204Pb up to 18.30). The coherence of all the isotopes suggests that helium behaves as an incompatible element, and that helium isotopic variations in the Hawaiian lavas are produced by melting and mantle processes, rather than magma chamber or metasomatic processes unique to the gaseous elements. The variations of He, Sr, and Nd are most pronounced in lavas of approximately 10 ka age range [Kurz and Kammer, 1991], but the largest Pb isotopic variation occurs earlier. These variations are interpreted as resulting from the diminishing contribution from the upwelling mantle plume material as the shield building ends at Mauna Loa. The order of reduction in the plume isotopic signature is inferred to be Pb (at >100 ka), He (at ˜14 ka), Sr (at ˜9 ka), and Nd (at ˜8 ka); the different timing may relate to silicate/melt partition coefficients, with most incompatible elements removed first, and also to concentration variations within the plume. Zr/Nb, Sr/Nb, and fractionation-corrected Nb concentrations, correlate with the isotopes and are significantly higher in some of the submarine SWR lavas, suggesting temporal variability on time scales similar to the Pb isotopes (i.e. ˜ 100 ka). Historical lavas define trace element and isotopic trends that are distinct from the longer term (10 to 100 ka) variations, suggesting that different processes cause the short term variability. The temporal evolution of Mauna Loa, and particularly the new data from the submarine SWR, suggest that the isotopic composition of the upwelling plume mantle is best represented by data from Loihi seamount tholeiites. The temporal evolution suggests that the mantle source of the latest stage of Mauna Loa, which is characterized by radiogenic 87Sr/86Sr (up to .70395), unradiogenic 206Pb/204Pb (˜18.0), 3He/4He ratios similar to MORB, and low Nb concentrations, is a small-volume contribution related to non-plume components (such as normal asthenosphere, or entrained mantle).

Origins of subcalcic garnets and their relation to diamond forming fluids—Case studies from Ekati (NWT-Canada) and Murowa (Zimbabwe)

NASA Astrophysics Data System (ADS)

Klein-BenDavid, Ofra; Graham Pearson, D.

2009-02-01

Subcalcic, high-Cr (G10) garnets are found as inclusions within diamonds and in peridotitic xenoliths. The strong spatial associations between G10 garnets and diamond make them an important tool in the investigation of diamond genesis. We present an integrated study of the major and trace element composition and oxygen-Sr-Nd-Hf isotopic ratios of eight G10 garnets from the Ekati mine (NWT-Canada) and four from the Murowa mine (Zimbabwe) in an attempt to determine their petrogenetic evolution and to further examine a possible relationship between the metasomatic agents responsible for G10 garnet signatures and diamond forming fluids. All garnets display sinusoidal to mildly sinusoidal REE patterns and have negative Ti, Sr and positive U anomalies. They have variably radiogenic 87Sr/ 86Sr (0.703261-0.731191) and non-radiogenic ɛNd values (-8.1 to -27.1), except for one sample from Murowa that has a positive ɛNd of 2.5. One Ekati sample has an extremely low ɛHf value of -61.6. The Ekati garnets we have studied all appear to come from a single depth in the Slave lithospheric mantle. On the base of Cr-Ca relations they have crystallized at 4.9 GPa and display dunitic Ca intercept values. Their δ 18O values range between +5.23‰ and +5.42‰. The Ekati G10 garnets record a complex, multi-stage metasomatic history involving the interaction of several components during their genesis. One metasomatic agent was enriched in HFSE, LREE, Sr, and depleted in Nb. This agent had the least radiogenic Sr. Another metasomatic agent had highly radiogenic Sr, and was enriched in LREE, Sr, Nb, Th and U. The G10 garnets have very low ɛNd and ɛHf values combined with radiogenic Sr, thus, they require an early lithospheric mantle enrichment event at some stage during their genesis or during the evolution of any precursor material that they formed from. The only Hf isotope composition measurable from the Ekati suite is so unradiogenic ( ɛHf = -61) that it yields a Lu/Hf model age of 3521 Ma. This indicates that the lithospheric enrichment event seen by the Ekati garnets or their precursors may have occurred in the early stages of the craton stabilization, during the diamond forming event [Westerlund K., Shirey S., Richardson S., Carlson R., Gurney J. and Harris J. (2006) A subduction wedge origin for Paleoarchean peridotitic diamonds and harzburgites from the Panda kimberlite, Slave craton: evidence from Re-Os isotope systematics. Contrib. Mineral. Petrol.152(3), 275-294]. Although our data cannot unequivocally discriminate between a variety of models for the genesis of subcalcic garnets it is clear that the host peridotite originated via melting at shallow depths followed by subduction and that the observed geochemical fingerprint of the garnets is strongly influenced by diamond forming fluids. Diamond forming fluids sampled from fibrous diamonds, have steep REE patterns, negative Ti and Sr anomalies and very low Sm/Nd ratios that are very similar to G10 garnet characteristics. These diamond forming fluids have been recently shown to have extreme Sr and Nd isotopic compositions [Klein-BenDavid O., Pearson D. G., Nowell G. M. and Cantigny P. (2008) Origins of diamond forming fluids—constraints from a coupled Sr-Nd isotope and trace element approach. Extended abstracts to the 9th International Kimberlite Conference, Frankfurt, Germany, 9IKC-A-00118.] that are closely concordant with G10 garnets. The fluids are also rich in LREE, P, K and water, sharing these features with mica-rich metasomes. These similarities suggest that ancient lithospheric metasomes could either provide a source region for, or be a product of diamond forming fluids. Diamond forming fluids appear to be intimately involved in the evolution of G10 garnets in the lithospheric mantle, either acting as a metasomatic agent, or being integral to triggering or enhancing garnet growth in a Cr-rich protolith. Such a link explains the strong association between G10 garnets and diamonds.

Low-temperature synthesis of homogeneous solid solutions of scheelite-structured Ca 1-xSr xWO 4 and Sr 1-xBa xWO 4 nanocrystals

DOE PAGES

Culver, Sean P.; Greaney, Matthew J.; Tinoco, Antonio; ...

2015-07-24

Here, a series of compositionally complex scheelite-structured nanocrystals of the formula A 1-xA’ xWO 4 (A = Ca, Sr, Ba) have been prepared under benign synthesis conditions using the vapor diffusion sol–gel method. Discrete nanocrystals with sub-20 nm mean diameters were obtained after kinetically controlled hydro- lysis and polycondensation at room temperature, followed by composition-dependent thermal aging at or below 60 °C. Rietveld analysis of X-ray diffraction data and Raman spectroscopy verified the synthesis of continuous and phase-pure nanocrystal solid solutions across the entire composition space for A 1-xA’ xWO 4, where 0 ≤ x ≤ 1. Elemental analysis bymore » X-ray photoelectron and inductively coupled plasma- atomic emission spectroscopies demonstrated excellent agreement between the nominal and experi- mentally determined elemental stoichiometries, while energy dispersive X-ray spectroscopy illustrated good spatial elemental homogeneity within these nanocrystals synthesized under benign conditions.« less

Bayesian Integration of Isotope Ratio for Geographic Sourcing of Castor Beans

DOE PAGES

Webb-Robertson, Bobbie-Jo; Kreuzer, Helen; Hart, Garret; ...

2012-01-01

Recenmore » t years have seen an increase in the forensic interest associated with the poison ricin, which is extracted from the seeds of the Ricinus communis plant. Both light element (C, N, O, and H) and strontium (Sr) isotope ratios have previously been used to associate organic material with geographic regions of origin. We present a Bayesian integration methodology that can more accurately predict the region of origin for a castor bean than individual models developed independently for light element stable isotopes or Sr isotope ratios. Our results demonstrate a clear improvement in the ability to correctly classify regions based on the integrated model with a class accuracy of 60.9 ± 2.1 % versus 55.9 ± 2.1 % and 40.2 ± 1.8 % for the light element and strontium (Sr) isotope ratios, respectively. In addition, we show graphically the strengths and weaknesses of each dataset in respect to class prediction and how the integration of these datasets strengthens the overall model.« less

Bayesian Integration of Isotope Ratios for Geographic Sourcing of Castor Beans

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

Webb-Robertson, Bobbie-Jo M.; Kreuzer, Helen W.; Hart, Garret L.

Recent years have seen an increase in the forensic interest associated with the poison ricin, which is extracted from the seeds of the Ricinus communis plant. Both light element (C, N, O, and H) and strontium (Sr) isotope ratios have previously been used to associate organic material with geographic regions of origin. We present a Bayesian integration methodology that can more accurately predict the region of origin for a castor bean than individual models developed independently for light element stable isotopes or Sr isotope ratios. Our results demonstrate a clear improvement in the ability to correctly classify regions based onmore » the integrated model with a class accuracy of 6 0 . 9 {+-} 2 . 1 % versus 5 5 . 9 {+-} 2 . 1 % and 4 0 . 2 {+-} 1 . 8 % for the light element and strontium (Sr) isotope ratios, respectively. In addition, we show graphically the strengths and weaknesses of each dataset in respect to class prediction and how the integration of these datasets strengthens the overall model.« less

Bayesian Integration of Isotope Ratio for Geographic Sourcing of Castor Beans

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

Webb-Robertson, Bobbie-Jo; Kreuzer, Helen; Hart, Garret

Recenmore » t years have seen an increase in the forensic interest associated with the poison ricin, which is extracted from the seeds of the Ricinus communis plant. Both light element (C, N, O, and H) and strontium (Sr) isotope ratios have previously been used to associate organic material with geographic regions of origin. We present a Bayesian integration methodology that can more accurately predict the region of origin for a castor bean than individual models developed independently for light element stable isotopes or Sr isotope ratios. Our results demonstrate a clear improvement in the ability to correctly classify regions based on the integrated model with a class accuracy of 60.9 ± 2.1 % versus 55.9 ± 2.1 % and 40.2 ± 1.8 % for the light element and strontium (Sr) isotope ratios, respectively. In addition, we show graphically the strengths and weaknesses of each dataset in respect to class prediction and how the integration of these datasets strengthens the overall model.« less

Bayesian Integration of Isotope Ratio for Geographic Sourcing of Castor Beans

PubMed Central

Webb-Robertson, Bobbie-Jo; Kreuzer, Helen; Hart, Garret; Ehleringer, James; West, Jason; Gill, Gary; Duckworth, Douglas

2012-01-01

Recent years have seen an increase in the forensic interest associated with the poison ricin, which is extracted from the seeds of the Ricinus communis plant. Both light element (C, N, O, and H) and strontium (Sr) isotope ratios have previously been used to associate organic material with geographic regions of origin. We present a Bayesian integration methodology that can more accurately predict the region of origin for a castor bean than individual models developed independently for light element stable isotopes or Sr isotope ratios. Our results demonstrate a clear improvement in the ability to correctly classify regions based on the integrated model with a class accuracy of 60.9 ± 2.1% versus 55.9 ± 2.1% and 40.2 ± 1.8% for the light element and strontium (Sr) isotope ratios, respectively. In addition, we show graphically the strengths and weaknesses of each dataset in respect to class prediction and how the integration of these datasets strengthens the overall model. PMID:22919270

Tracing Anthropogenic Salinity Inputs to the Semi-arid Rio Grande River: A Multi-isotope Tracer (U, S, B and Sr) Approach

NASA Astrophysics Data System (ADS)

Garcia, S.; Nyachoti, S. K.; Ma, L.; Szynkiewicz, A.; McIntosh, J. C.

2015-12-01

High salinity in the Rio Grande has led to severe reductions in crop productivity and accumulation of salts in soils. These pressing issues exist for other arid rivers worldwide. Salinity contributions to the Rio Grande have not been adequately quantified, especially from agriculture, urban activities, and geological sources. Here, we use major element concentrations and U, S, B, Sr isotopic signatures to fingerprint the salinity sources. Our study area focuses on a 200 km long stretch of the Rio Grande from Elephant Butte Reservoir, NM to El Paso, TX. River samples were collected monthly from 2014 to 2015. Irrigation drains, groundwater wells, city drains and wastewater effluents were sampled as possible anthropogenic salinity end-members. Major element chemistry, U, S and Sr isotope ratios in the Rio Grande waters suggest multiple salinity inputs from geological, agricultural, and urban sources. Natural upwelling of groundwater is significant for the Rio Grande near Elephant Butte, as suggested by high TDS values and high (234U/238U), 87Sr/86Sr, δ34S ratios. Agricultural activities (e.g. flood irrigation, groundwater pumping, fertilizer use) are extensive in the Mesilla Valley. Rio Grande waters from this region have characteristic lower (234U/238U), 87Sr/86Sr, and δ34S ratios, with possible agricultural sources from use of fertilizers and gypsum. Agricultural practices during flood irrigation also intensify evaporation of Rio Grande surface water and considerably increase water salinity. Shallow groundwater signatures were also identified at several river locations, possibly due to the artificial pumping of local groundwater for irrigation. Impacts of urban activities to river chemistry (high NO3 and B concentrations) were evident for locations downstream to Las Cruces and El Paso wastewater treatment plants, supporting the use of the B isotope as an urban salinity tracer. This study improves our understanding of human impacts on water quality and elemental cycles.

The Universality of the Rapid Neutron-capture Process Revealed by a Possible Disrupted Dwarf Galaxy Star

NASA Astrophysics Data System (ADS)

Casey, Andrew R.; Schlaufman, Kevin C.

2017-12-01

The rapid neutron-capture or r-process is thought to produce the majority of the heavy elements (Z> 30) in extremely metal-poor stars. The same process is also responsible for a significant fraction of the heavy elements in the Sun. This universality of the r-process is one of its characteristic features, as well as one of the most important clues to its astrophysical origin. We report the discovery of an extremely metal-poor field giant with [{Sr},{Ba}/{{H}}]≈ -6.0 and [{Sr},{Ba}/{Fe}]≈ -3.0, the lowest abundances of strontium and barium relative to iron ever observed. Despite its low abundances, the star 2MASS J151113.24-213003.0 has [{Sr}/{Ba}]=-0.11+/- 0.14, therefore its neutron-capture abundances are consistent with the main solar r-process pattern that has [{Sr}/{Ba}]=-0.25. It has been suggested that extremely low neutron-capture abundances are a characteristic of dwarf galaxies, and we find that this star is on a highly eccentric orbit with an apocenter ≳100 kpc that lies in the disk of satellites in the halo of the Milky Way. We show that other extremely metal-poor stars with low [Sr, Ba/H] and [Sr, Ba/Fe] plus solar [Sr/Ba] tend to have orbits with large apocenters, consistent with a dwarf galaxy origin for this class of object. The nucleosynthesis event that produced the neutron-capture elements in 2MASS J151113.24-213003.0 must produce both strontium and barium together in the solar ratio. We exclude contributions from the s-process in intermediate-mass asymptotic giant branch or fast-rotating massive metal-poor stars, pair-instability supernovae, the weak r-process, and neutron-star mergers. We argue that the event was a Pop III or extreme Pop II core-collapse supernova explosion. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Geochemistry of the mantle beneath the Rodriguez Triple Junction and the South-East Indian Ridge

NASA Astrophysics Data System (ADS)

Michard, A.; Montigny, R.; Schlich, R.

1986-05-01

Rare earth element abundances and Sr, Nd. Pb isotope compositions have been measured on zero-age dredge samples from the Rodriguez Triple Junction (RTJ) and the South-East Indian Ridge (SEIR), Along the SEIR. the geochemical "halo" of the St. Paul hot spot has a half-width of about 400 km and the data may be fairly well accounted for by a binary mixing between an Indian MORB-type component ( 87Sr/ 86Sr = 0.7028. 143Nd/ 144Nd = 0.51304. 206Pb/ 204Pb = 17.8) and the plume-type St. Paul component (0.7036, 0.5129, and 18.7 respectively). The alignment of the lead isotope data is particularly good with an apparent age of 1.95 ± 0.13 Ga and Th/U source value of 3.94. One sample dredged on the ridge 60 km southeast of St. Paul bears a definite Kerguelen isotopic signature. The RTJ has distinctive geochemical properties which contrast with those of the adjacent ridge segments. Low 206Pb/ 204Pb ratios which plots to the left of the geochron, rather high 208Pb/ 204Pb and 87Sr/ 87Sr ratios (17.4. 37.4, and 0.7031 respectively), a striking isotopic homogeneity, and variable LREE/HREE fractionation with (La/Sm) N, = 0.3-0.8 make this triple junction an anomalous site. The geochemical properties of the Indian Ocean basats have been examined using a three-component mantle model involving (a) a normal MORB-type source though to represent the depleted upper mantle matrix, (b) an OIB-type source of uncertain parentage (recycled oceanic crust?), and (c) a component with low μ. low Sm/Nd. high Rb/Sr (time-averaged value) which is tentatively assigned to ancient hydrothermal and abyssal sediments recycled in the mantle. The high 208Pb/ 204Pb and 87Sr/ 86Sr ratios typical of the Dupal anomaly are likely due to the widespread distribution of this latter component in the basalt source from this area. including that for MORBs.

Electrochemical Impedance Spectroscopic Study on Eu 2+ and Sr 2+ Using Liquid Metal Cathodes in Molten Chlorides

NASA Astrophysics Data System (ADS)

Matsumiya, Masahiko; Takagi, Ryuzo

2000-08-01

For the pyrochemical reprocessing of spent metallic nuclear fuels in molten salt baths it is important to investigate the behavior of the electrochemically negative elements Eu and Sr, which are significant fission products. Voltammetric and chronopotentiometric studies have shown that the reduction of Eu 2+ and Sr 2+ on liquid Pb cathodes in molten chloride baths at 1073 K follows the alloy formation reaction: Eu 2+ + 2e- + 3Pb → EuPb 3 and Sr 2+ + 2e- + 3Pb → SrPb 3 . In the present work these alloy formation reactions were studiedby electrochemical impedance spectroscopy. Analysis of the spectra showed that the electronic exchange of Eu 2+ /Eu and Sr 2+ /Sr is quasi-re-versible. Moreover, the experimental results allowed the determination of the kinetic parameters of EU 2+ /EU and Sr 2+ /Sr, the diffusion coefficients of these species in molten chloride baths, and also the diffusion layer thickness.

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.

Isotopic composition of strontium in three basalt-andesite centers along the Lesser Antilles arc

USGS Publications Warehouse

Hedge, C.E.; Lewis, J.F.

1971-01-01

Si87/Sr86 ratios have been determined for lavas and py lastic rocks from three basalt-andesite centers along the Lesser Antilles arc-Mt. Misery on the island of St. Kitts, Soufriere on the island of St. Vincent, and Carriacou, an island of The Grenadines. The average Si87/Sr86 content of these rocks is 0.7038 for Mt. Misery, 0.7041 for Soufriere, and 0.7053 for Carriacou. All the Sr87/Sr86 values from each center are the same within analytical uncertainty (??0.0002). The constancy of strontium isotopic data within each center supports the hypothesis that basalts and andesites for each specific center investigated are generated from the same source - in agreement with petrographic and major- and minor-element data. Strontium isotopic compositions and elemental concentrations, particularly of strontium and nickel, indicate that this source was mantle peridotite and that the relationship between the respective basalts and andesites is probably fractional crystallization. ?? 1971 Springer-Verlag.

MORB mantle hosts the missing Eu (Sr, Nb, Ta and Ti) in the continental crust: New perspectives on crustal growth, crust-mantle differentiation and chemical structure of oceanic upper mantle

NASA Astrophysics Data System (ADS)

Niu, Yaoling; O'Hara, Michael J.

2009-09-01

We have examined the high quality data of 306 mid-ocean ridge basalt (MORB) glass samples from the East Pacific Rise (EPR), near-EPR seamounts, Pacific Antarctic Ridge (PAR), near-PAR seamounts, Mid-Atlantic Ridge (MAR), and near-MAR seamounts. The data show a correlated variation between Eu/Eu* and Sr/Sr*, and both decrease with decreasing MgO, pointing to the effect of plagioclase crystallization. The observation that samples with MgO > 9.5 wt.% (before plagioclase on the liquidus) show Eu/Eu* > 1 and Sr/Sr* > 1 and that none of the major phases (i.e., olivine, orthopyroxene, clinopyroxene, spinel and garnet) in the sub-ridge mantle melting region can effectively fractionate Eu and Sr from otherwise similarly incompatible elements indicates that the depleted MORB mantle (DMM) possesses excess Sr and Eu, i.e., [Sr/Sr*]DMM > 1 and [Eu/Eu*]DMM > 1. Furthermore, the well-established observation that DNb ≈ DTh, DTa ≈ DU and DTi ≈ DSm during MORB mantle melting, yet primitive MORB melts all have [Nb/Th]PMMORB > 1, [Ta/U]PMMORB > 1 and [Ti/Sm]PMMORB > 1 (where PM indicates primitive mantle normalized), also points to the presence of excess Nb, Ta and Ti in the DMM, i.e., [Nb/Th]PMDMM > 1, [Ta/U]PMDMM > 1 and [Ti/Sm]PMDMM > 1. The excesses of Eu, Sr, Nb, Ta and Ti in the DMM complement the well-known deficiencies of these elements in the bulk continental crust (BCC). These new observations, which support the notion that the DMM and BCC are complementary in terms of the overall abundances of incompatible elements, offer new insights into the crust-mantle differentiation. These observations are best explained by partial melting of amphibolite of MORB protolith during continental collision, which produces andesitic melts with a remarkable compositional (major and trace element abundances as well as key elemental ratios) similarity to the BCC, as revealed by andesites in southern Tibet produced during the India-Asia continental collision. An average amphibolite of MORB protolith consists of ~ 66.4% amphibole, ~ 29.2% plagioclase and 4.4% ilmenite. In terms of simple modal melting models, the bulk distribution coefficient ratios D2Eu/(Sm + Gd) = 1.21, D2Sr/(Pr + Nd) = 1.04, DNb/Th = 44, DTa/U = 57, DTi/Sm = 3.39 and DNb/Ta = 1.30 readily explains the small but significant negative Eu and Sr anomalies, moderate negative Ti anomaly and huge negative Nb and Ta anomalies as well as the more sub-chondritic Nb/Ta ratio in the syncollisional andesitic melt that is characteristic of and contributes to the continental crust mass. These results support the hypothesis that continental collision zones are primary sites of net continental crust growth, whereas the standard "island arc" model has many more difficulties than certainties. That is, it is the continental collision (vs. "island arc magmatism" or "episodic super mantle avalanche events") that produces and preserves the juvenile crust, and hence maintains net continental growth. The data also allow us to establish the robust composition of depleted and most primitive (or "primary") MORB melt with 13% MgO. This, together with the estimated positive Eu and Sr anomalies in the DMM, further permits estimation that the DMM may occupy the uppermost ~ 680 km of the convective mantle following the tradition that the DMM lies in the shallowest mantle. However, the tradition may be in error. The seismic low velocity zone (LVZ) may be compositionally stratified with small melt fractions concentrated towards the interface with the growing lithosphere because of buoyancy. Such small melt fractions, enriched in volatiles and incompatible elements, continue to metasomatize the growing lithosphere before it reaches the full thickness after ~ 70 Myrs. Hence, the oceanic mantle lithosphere is a huge enriched geochemical reservoir. On the other hand, deep portions of the LVZ, which are thus relatively depleted, become the primary source feeding the ridge because of ridge-suction-driven lateral material supply to form the crust and much of the lithosphere at and in the vicinity of the ridge.

Strontium (Sr) separation from seawater using titanate adsorbents: Effects of seawater matrix ions on Sr sorption behavior

NASA Astrophysics Data System (ADS)

Ryu, Jungho; Hong, Hye-jin; Ryu, Taegong; Park, In-Su

2017-04-01

Strontium (Sr) which has many industrial applications such as ferrite magnet, ceramic, and fire works exists in seawater with the concentration of approximately 7 mg/L. In previous report estimating economic potential on recovery of various elements from seawater in terms of their commercial values and concentrations in seawater, Sr locates upper than approximate break-even line, which implies Sr recovery from seawater can be potentially profitable. Recently, Sr separation from seawater has received great attention in the environmental aspect after Fukushima Nuclear Power Plant (NPP) accident which released much amount of radioactive Sr and Cs. Accordingly, the efficient separation of radioactive elements released to seawater has become critical as an important technological need as well as their removal from radioactive wastes. So far, it has been introduced to separate Sr from aqueous media by various methods including solvent extraction, adsorption by solid materials, and ion exchange. Among them, the adsorption technique using solid adsorbents is of great interest for selectively separating Sr from seawater with respect to low concentration level of Sr. In this study, we synthesized titanate nanotube (TiNT) by simple hydrothermal reaction, characterized its physicochemical properties, and systematically evaluated Sr sorption behavior under various reaction conditions corresponding to seawater environment. The synthesized TiNT exhibited the fibril-type nanotube structure with high specific surface area of 260 m2/g. The adsorption of Sr on TiNT rapidly occurred following pseudo-second-order kinetic model, and was in good agreement with Langmuir isotherm model, indicating maximum adsorption capacity of 97 mg/g. Based on Sr uptake and Na release with stoichiometric balance, sorption mechanism of Sr on TiNT was found to be ion-exchange between Na in TiNT lattice and Sr in solution phase, which was also confirmed by XRD and Raman analysis. Among competitive ions, Ca significantly hindered Sr sorption on TiNT, whereas Na had little effect on Sr sorption despite the sorption mechanism of Na-exchange. The effect of Ca on Sr sorption was evaluated in detail by introducing distribution coefficient (Kd) that is critical factor to determine the selectivity, revealing slightly higher selectivity for Sr. The adsorption-desoption test of Sr in real seawater medium enabled to determine Kd and concentration factor (CF) for co-existing matrix ions in seawater, and these values were assessed in both aspects of removal and recovery of Sr from seawater. The TiNT could be easily regenerated by acid treatment and reused for repeated cycle, supporting its long term use for the practical application of removing and recovering Sr from seawater.

Ca isotope fractionation and Sr/Ca partitioning associated with anhydrite formation at mid-ocean ridge hydrothermal systems: An experimental approach

NASA Astrophysics Data System (ADS)

Syverson, D. D.; Scheuermann, P.; Pester, N. J.; Higgins, J. A.; Seyfried, W. E., Jr.

2016-12-01

The elemental and isotopic mass balance of Ca and Sr between seawater and basalt at mid-ocean ridge (MOR) hydrothermal systems is an integrated reflection of the various physiochemical processes, which induce chemical exchange, in the subseafloor. Specifically, the processes of anhydrite precipitation and recrystallization are recognized to be important controls on governing the Ca and Sr elemental and isotope compositions of high temperature vent fluids, however, few experimental data exist to constrain these geochemical effects. Thus, to better understand the associated Sr/Ca partitioning and Ca isotope fractionation and rate of exchange between anhydrite and dissolved constituents, anhydrite precipitation and recrystallization experiments were performed at 175, 250, and 350°C and 500 bar at chemical conditions indicative of active MOR hydrothermal systems. The experimental data suggest that upon entrainment of seawater into MOR hydrothermal systems, anhydrite will precipitate rapidly and discriminate against the heavy isotopes of Ca (Δ44/40Ca(Anh-Fluid) = -0.68 - -0.25 ‰), whereas Sr/Ca partitioning depends on the saturation state of the evolving hydrothermal fluid with respect to anhydrite at each PTX (KD(Anh-Fluid) = 1.24 - 0.55). Coupling experimental constraints with the temperature gradient inferred for high temperature MOR hydrothermal systems in the oceanic crust, data suggest that the Ca isotope and Sr elemental composition of anhydrite formed near the seafloor will be influenced by disequilibrium effects, while, at higher temperatures further into the oceanic crust, anhydrite will be representative of equilibrium Sr/Ca partitioning and Ca isotope fractionation conditions. These experimental observations are consistent with analyzed Sr/Ca and Ca isotope compositions of anhydrites and vent fluids sampled from modern MOR hydrothermal systems1,2 and can be used to further constrain the geochemical effects of hydrothermal circulation in the oceanic crust throughout Earth's history. 1 Tivey, M. K. Generation of Seafloor Hydrothermal Deposits. Oceanography 20, 50-66 (2007).2 Amini, M. et al. Calcium isotope (δ44/40Ca) fractionation along hydrothermal pathways, Logatchev field (Mid-Atlantic Ridge, 14°45'N). Geochimica et Cosmochimica Acta 72, 4107-4122 (2008).

Multielement analysis of Canadian wines by inductively coupled plasma mass spectrometry (ICP-MS) and multivariate statistics.

PubMed

Taylor, Vivien F; Longerich, Henry P; Greenough, John D

2003-02-12

Trace element fingerprints were deciphered for wines from Canada's two major wine-producing regions, the Okanagan Valley and the Niagara Peninsula, for the purpose of examining differences in wine element composition with region of origin and identifying elements important to determining provenance. Analysis by ICP-MS allowed simultaneous determination of 34 trace elements in wine (Li, Be, Mg, Al, P, Cl, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Mo, Ag, Cd, Sb, I, Cs, Ba, La, Ce, Tl, Pb, Bi, Th, and U) at low levels of detection, and patterns in trace element concentrations were deciphered by multivariate statistical analysis. The two regions were discriminated with 100% accuracy using 10 of these elements. Differences in soil chemistry between the Niagara and Okanagan vineyards were evident, without a good correlation between soil and wine composition. The element Sr was found to be a good indicator of provenance and has been reported in fingerprinting studies of other regions.

Nanostructured crystals of fluorite phases Sr1 - x R x F2 + x ( R are rare-earth elements) and their ordering: IV. Study of the optical transmission spectra in the 2-17-μm wavelength range

NASA Astrophysics Data System (ADS)

Fedorov, V. A.; Karimov, D. N.; Komar'kova, O. N.; Krivandina, E. A.; Zhmurova, Z. I.; Sobolev, B. P.

2010-01-01

Transmission spectra of two-component crystals of Sr1- x R x F2+ x ( R = Y, La-Lu; 0 ≤ x ≤ 0.5) in the 1-17-μm wavelength range were studied. The spectral characteristics of these crystals and of single-component crystals of MF2 ( M = Ca, Sr, or Ba) and RF3 ( R = La-Nd) were compared. The transmission cutoff of Sr1- x R x F2+ x crystals is shifted to shorter wavelengths with increasing x. The same tendency is observed with the increasing atomic number R of rare-earth elements for two isoconcentration series of Sr1- x R x F2+ x ( x ˜ 0.10 and 0.28). This tendency is pronounced at large x. The transmission cutoff of Sr1- x R x F2+ x crystals can be varied in the range of from 10.7 to 12.2 μm by changing their qualitative ( R) and quantitative ( x) composition. Hence, these crystals can be assigned to multicomponent fluoride optical materials with controlled optical characteristics. The Sr1- x R x F2+ x crystals, where R = Ce-Sm, were shown to be promising materials for the design of selective optical filters in the 2-10-μm spectral range.

Pulsed 86Sr-labeling and NanoSIMS imaging to study coral biomineralization at ultra-structural length scales

NASA Astrophysics Data System (ADS)

Brahmi, C.; Domart-Coulon, I.; Rougée, L.; Pyle, D. G.; Stolarski, J.; Mahoney, J. J.; Richmond, R. H.; Ostrander, G. K.; Meibom, A.

2012-09-01

A method to label marine biocarbonates is developed based on a concentration enrichment of a minor stable isotope of a trace element that is a natural component of seawater, resulting in the formation of biocarbonate with corresponding isotopic enrichments. This biocarbonate is subsequently imaged with a NanoSIMS ion microprobe to visualize the locations of the isotopic marker on sub-micrometric length scales, permitting resolution of all ultra-structural details. In this study, a scleractinian coral, Pocillopora damicornis, was labeled 3 times with 86Sr-enhanced seawater for a period of 48 h with 5 days under normal seawater conditions separating each labeling event. Two non-specific cellular stress biomarkers, glutathione-S-transferase activity and porphyrin concentration plus carbonic anhydrase, an enzymatic marker involved in the physiology of carbonate biomineralization, as well as unchanged levels of zooxanthellae photosynthesis efficiency indicate that coral physiological processes are not affected by the 86Sr-enhancement. NanoSIMS images of the 86Sr/44Ca ratio in skeleton formed during the experiment allow for a determination of the average extension rate of the two major ultra-structural components of the coral skeleton: Rapid Accretion Deposits are found to form on average about 4.5 times faster than Thickening Deposits. The method opens up new horizons in the study of biocarbonate formation because it holds the potential to observe growth of calcareous structures such as skeletons, shells, tests, spines formed by a wide range of organisms under essentially unperturbed physiological conditions.

Evolution of the lunar highland crust

NASA Technical Reports Server (NTRS)

Taylor, S. R.; Bence, A. E.

1975-01-01

The evolution of three distinct element associations in the lunar highland crust is discussed in terms of the Taylor-Jakes model which involves melting of most of the moon during accretion. Sources for (1) high Ca, Al, Sr, Eu, (2) high Mg and Cr, and (3) high K, REE, Zr, Hf, Nb are suggested. Bombardment by large projectiles during the differentiation process causes melting and mixing, which produces a wide range of compositions in the crust. The formation of dunite, troctolite, high-, medium-, and low-K Fra Mauro basalts, and rocks close to the olivine-spinel-plagioclase peritectic point is considered.

Rare earth elements and (87)Sr/(86)Sr isotopic characterization of Indian Basmati rice as potential tool for its geographical authenticity.

PubMed

Lagad, Rupali A; Singh, Sunil K; Rai, Vinai K

2017-02-15

The increasing demand for premium priced Indian Basmati rice (Oryza sativa) in world commodity market causing fraudulent activities like adulteration, mislabelling. In order to develop authentication method for Indian Basmati rice, (87)Sr/(86)Sr ratios and REEs composition of Basmati rice, soil and water samples were determined and evaluated their ability as geographical tracer in the present study. In addition, the possible source of Sr in rice plant has also been examined. Basmati rice samples (n=82) showed (87)Sr/(86)Sr ratios in the range 0.71143-0.73448 and concentrations of 10 REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er, Yb) in ppb levels. Statistical analysis showed strong correlation between (87)Sr/(86)Sr ratios of rice, silicate and carbonate fractions of soil. Good correlation and closeness of (87)Sr/(86)Sr of rice with water indicate its uptake in rice from water. Rice grown in southern Uttar Pradesh contains higher (87)Sr/(86)Sr compared to other region of Indo-Gangetic Plain due to higher (87)Sr/(86)Sr of the Ganga compared to other rivers. (87)Sr/(86)Sr ratios can be used as a tracer for differentiating Indian Basmati rice from the other country originated rice samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

[The functions of calcium-sensing receptor in regulating mineral metabolism.

PubMed

Kinoshita, Yuka

Calcium-sensing receptor(CaSR)which belongs to a G protein-coupled receptor family is one of the key elements in regulating calcium homeostasis. CaSR has been identified as a receptor to control parathyroid hormone(PTH)secretion in parathyroid glands according to serum calcium ion(Ca2+)levels. It has also been shown that CaSR controls reabsorption of water and several cations including Ca2+and magnesium ion(Mg2+)in renal tubular cells. This review summarizes the functions and roles of CaSR in mineral metabolism that are exerted in parathyroid glands, kidney, and intestine.

A geochemical study of Nea-Kameni hyalodacites (Santorini Volcano, Aegean island arc). Inferences concerning the origin and effects of solfataras and magmatic evolution

NASA Astrophysics Data System (ADS)

Briqueu, Louis; Lancelot, Joël R.

1984-03-01

Since the Santorini Volcano (Aegean arc, eastern Mediterranean Sea) collapsed, volcanic activity has been located at the center of the flooded caldera. Over the past 800 years, five lava flows have formed one of the central islets (Nea-Kameni). Since 1951, when the last eruption occurred, a permanent fumarolic activity has remained. We present chemical analyses (major elements, trace-elements and Sr isotopic ratios) of ten samples from the five hyalodacitic lava flows, showing different stages of alteration, from a completely fresh lava up to one bearing native sulfur and other sublimates. Only the macroscopic aspect of these hyalodacites is affected by fumarolic activity. The elements that are mobile as a result of hydrothermal processes, such as the alkaline (K, Rb) or the chalcophile elements (Zn, Pb), show great homogeneity; the same can be said for the Sr isotopic compositions which range from 0.7046 to 0.7049. None of the analyzed samples has an Sr isotopic composition as high as those reported by Puchelt and Hoefs (1971) for rock samples collected in the same lava flows. If we take into account the marine surroundings of Nea-Kameni islet, these observations put severe restraints on the different hypotheses regarding the origin of the halogens (seawater or meteoric water). The contamination processes of these dacitic lavas are clearly less important than assumed by other authors according to previous Sr isotopic data. Finally, the homogeneity of the elements with low partition coefficients is sufficient to show that the magma has not undergone any perceptible evolution during the last 300 years.

Geochemical evolution of Jurassic diorites from the Bristol Lake region, California, USA, and the role of assimilation

USGS Publications Warehouse

Young, E.D.; Wooden, J.L.; Shieh, Y.-N.; Farber, D.

1992-01-01

Late Jurassic dioritic plutons from the Bristol Lake region of the eastern Mojave Desert share several geochemical attributes with high-alumina basalts, continental hawaiite basalts, and high-K are andesites including: high K2O concentrations; high Al2O3 (16-19 weight %); elevated Zr/TiO2; LREE (light-rare-earth-element) enrichment (La/YbCN=6.3-13.3); and high Nb. Pearce element ratio analysis supported by petrographic relations demonstrates that P, Hf, and Zr were conserved during differentiation. Abundances of conserved elements suggest that dioritic plutons from neighboring ranges were derived from similar parental melts. In the most voluminous suite, correlated variations in elemental concentrations and (87Sr/86Sr)i indicate differentiation by fractional crystallization of hornblende and plagioclase combined with assimilation of a component characterized by abundant radiogenic Sr. Levenberg-Marquardt and Monte Carlo techniques were used to obtain optimal solutions to non-linear inverse models for fractional crystallization-assimilation processes. Results show that the assimilated material was chemically analogous to lower crustal mafic granulites and that the mass ratio of contaminant to parental magma was on the order of 0.1. Lack of enrichment in 18O with differentiation is consistent with the model results. Elemental concentrations and O, Sr, and Nd isotopic data point to a hydrous REE-enriched subcontinental lithospheric source similar to that which produced some Cenozoic continental hawaiites from the southern Cordillera. Isotopic compositions of associated granitoids suggest that partial melting of this subcontinental lithosphere may have been an important process in the development of the Late Jurassic plutonic arc of the eastern Mojave Desert. ?? 1992 Springer-Verlag.

Effect of Wood Aging on Wine Mineral Composition and 87Sr/86Sr Isotopic Ratio.

PubMed

Kaya, Ayse D; Bruno de Sousa, Raúl; Curvelo-Garcia, António S; Ricardo-da-Silva, Jorge M; Catarino, Sofia

2017-06-14

The evolution of mineral composition and wine strontium isotopic ratio 87 Sr/ 86 Sr (Sr IR) during wood aging were investigated. A red wine was aged in stainless steel tanks with French oak staves (Quercus sessiliflora Salisb.), with three industrial scale replicates. Sampling was carried out after 30, 60, and 90 days of aging, and the wines were evaluated in terms of general analysis, phenolic composition, total polysaccharides, multielement composition, and Sr IR. Li, Be, Mg, Al, Sc, Ti, V, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Mo, Sb, Cs, Ba, Pr, Nd, Sm, Eu, Dy, Ho, Er, Yb, Lu, Tl, and Pb elements and 87 Sr/ 86 Sr were determined by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) and Na, K, Ca, and Fe by flame atomic absorption spectrometry (FAAS). Two-way ANOVA was applied to assess wood aging and time effect on Sr IR and mineral composition. Wood aging resulted in significantly higher concentrations of Mg, V, Co, Ni, and Sr. At the end of the aging period, wine exhibited statistically identical Sr IR compared to control. Study suggests that wood aging does not affect 87 Sr/ 86 Sr, not precluding the use of this parameter for wine traceability purposes.

Pyroxenite and peridotite xenoliths from Hexigten, Inner Mongolia: Insights into the Paleo-Asian Ocean subduction-related melt/fluid-peridotite interaction

NASA Astrophysics Data System (ADS)

Zou, Dongya; Liu, Yongsheng; Hu, Zhaochu; Gao, Shan; Zong, Keqing; Xu, Rong; Deng, Lixu; He, Detao; Gao, Changgui

2014-09-01

The in situ major, trace-element and Sr-isotopic compositions of the peridotite and pyroxenite xenoliths from the Hexigten region in the Xing-Meng orogenic belt (XMOB) were examined to evaluate the influences and contributions of the Paleo-Asian Oceanic slab subduction on the lithospheric mantle transformation. Pyroxenes in the Type 1 pyroxenite exhibit low and variable Mg# (67-85) and relatively high 87Sr/86Sr ratios (0.7036-0.7053), indicating that they were formed by assimilation and fractional crystallization processes during a basaltic underplating event. The peridotite and Type 2 pyroxenite xenoliths sampled the lithospheric mantle and recorded subduction-related metasomatism. The mineral chemistries of the Type 1 peridotite suggest that the lithospheric mantle beneath this area suffered 1-15% melt extraction. Clinopyroxene (Cpx) in some Type 1 peridotites are characterized by high (La/Yb)N coupled with marked depletions in high field strength elements (HFSE) (Nb, Ta, Zr, Hf and Ti) and negative correlations between the low Ti/Eu (Nb/La) and 87Sr/86Sr ratios (0.7037-0.7055), suggesting metasomatism by subduction-related CO2-rich fluids. Olivine (Ol) and orthopyroxene (Opx) in the Type 2 peridotite are characterized by a relatively low Mg# but high Ni contents. In addition to the normal incompatible element-depleted Opx, Opx with enrichments in Rb, Ba, Th, U, Nb, Ta and LREE were observed, as well. The Mg# of incompatible element-depleted Opx exhibits weak zonations (i.e., decreasing from the cores to the rims). Cpx and Opx of the Type 2 pyroxenite exhibit similarly high Mg# and Ni contents. Rb, Ba, Th, U, Nb, Ta and LREE contents and 87Sr/86Sr ratios of the Cpx increase from the cores to the rims. Moreover, Opx in the Type 2 peridotite and Cpx in the Type 2 pyroxenite exhibit increased Nb/Ta ratios and Ni contents relative to those in the Type 1 peridotites. These observations collectively suggest a rutile-bearing eclogite-derived silicic melt-peridotite reaction as the origin for the Type 2 peridotite and pyroxenite. Considering the geological setting, it is suggested that the melt/fluid-peridotite interactions were caused by the Paleo-Asian Ocean subduction, which could have contributed significantly to the transformation of the lithospheric mantle beneath the northern margin of the NCC, as well.

Rapid sequential determination of Pu, 90Sr and 241Am nuclides in environmental samples using an anion exchange and Sr-Spec resins.

PubMed

Lee, M H; Ahn, H J; Park, J H; Park, Y J; Song, K

2011-02-01

This paper presents a quantitative and rapid method of sequential separation of Pu, (90)Sr and (241)Am nuclides in environmental soil samples with an anion exchange resin and Sr Spec resin. After the sample solution was passed through an anion exchange column connected to a Sr Spec column, Pu isotopes were purified from the anion exchange column. Strontium-90 was separated from other interfering elements by the Sr Spec column. Americium-241 was purified from lanthanides by the anion exchange resin after oxalate co-precipitation. Measurement of Pu and Am isotopes was carried out using an α-spectrometer. Strontium-90 was measured by a low-level liquid scintillation counter. The radiochemical procedure of Pu, (90)Sr and (241)Am nuclides investigated in this study validated by application to IAEA reference materials and environmental soil samples. Copyright © 2010 Elsevier Ltd. All rights reserved.

Determining baseline element composition of lichens. I. Parmelia sulcata at Theodore Roosevelt national park, North Dakota

USGS Publications Warehouse

Gough, L.P.; Severson, R.C.; Jackson, L.L.

1988-01-01

Element-concentration baselines are given for Parmelia sulcata and associated soils. Parmelia chlorochroa was found sporadically and therefore only representative concentration ranges are reported for this species. Element data include (1) for lichens; Al, As, Ba, B, Ca, Cr, Cu, Fe, Hg, Mn, Ni, P, Sr, S, Ti, V, Y, and Zn; and (2) for soils: Al, Ba, Be, Ca, Cs, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Nb, P, Pb, Sr, S, Ti, V, Y, and Zn. Very little (usually 7.2 km); thus, P sulcata is, in general, chemically similar throughout the park. This same uniformity was found for soil geochemistry. Numerous samples collected at close intervals would be required, therefore, to produce detailed element-concentration maps for P. sulcata and soils. No instances of elemental phytotoxic conditions were found; however, P. sulcata apparently possesses large concentrations of Ba, Cu, Fe, Pb, S, V, and possibly Zn.

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.

Evaluating the usability of speech recognition to create clinical documentation using a commercial electronic health record.

PubMed

Hodgson, Tobias; Magrabi, Farah; Coiera, Enrico

2018-05-01

To conduct a usability study exploring the value of using speech recognition (SR) for clinical documentation tasks within an electronic health record (EHR) system. Thirty-five emergency department clinicians completed a system usability scale (SUS) questionnaire. The study was undertaken after participants undertook randomly allocated clinical documentation tasks using keyboard and mouse (KBM) or SR. SUS scores were analyzed and the results with KBM were compared to SR results. Significant difference in SUS scores between EHR system use with and without SR were observed (KBM 67, SR 61; P = 0.045; CI, 0.1 to 12.0). Nineteen of 35 participants scored higher for EHR with KBM, 11 higher for EHR with SR and 5 gave the same score for both. Factor analysis showed no significant difference in scores for the sub-element of usability (EHR with KBM 65, EHR with SR 62; P = 0.255; CI, -2.6 to 9.5). Scores for the sub-element of learnability were significantly different (KBM 72, SR 55; P < 0.001; CI, 9.8 to 23.5). A significant correlation was found between the perceived usability of the two system configurations (EHR with KBM or SR) and the efficiency of documentation (time to document) (P = 0.002; CI, 10.5 to -0.1) but not with safety (number of errors) (P = 0.90; CI, -2.3 to 2.6). SR was associated with significantly reduced overall usability scores, even though it is often positioned as ease of use technology. SR was perceived to impose larger costs in terms of learnability via training and support requirements for EHR based documentation when compared to using KBM. Lower usability scores were significantly associated with longer documentation times. The usability of EHR systems with any input modality is an area that requires continued development. The addition of an SR component to an EHR system may cause a significant reduction in terms of perceived usability by clinicians. Copyright © 2018 Elsevier B.V. All rights reserved.

Photoelectron energy-loss study of the Bi2CaSr2Cu2O8 superconductor

NASA Astrophysics Data System (ADS)

Shen, Z.-X.; Lindberg, P. A. P.; Dessau, D. S.; Lindau, I.; Spicer, W. E.; Mitzi, D. B.; Bozovic, I.; Kapitulnik, A.

1989-03-01

Using energy-loss spectroscopy of photoelectrons from a single crystal of Bi2CaSr2Cu2O8, we show that the electronic structure of the near-surface region is the same as that of the bulk. Utilizing the fact that photoelectrons of different elements are excited at different locations in the unit cell, we identify the energy-loss features as due to valence plasmon excitations, and one-electron excitations by comparing the photoelectron energy-loss spectra of the different elements.

Impacts of Dust on Tropical Volcanic Soil Formation: Insights from Strontium and Uranium-Series Isotopes in Soils from Basse-Terre Island, French Guadeloupe

NASA Astrophysics Data System (ADS)

Pereyra, Y.; Ma, L.; Sak, P. B.; Gaillardet, J.; Buss, H. L.; Brantley, S. L.

2015-12-01

Dust inputs play an important role in soil formation, especially for thick soils developed on tropical volcanic islands. In these regions, soils are highly depleted due to intensive chemical weathering, and mineral nutrients from dusts have been known to be important in sustaining soil fertility and productivity. Tropical volcanic soils are an ideal system to study the impacts of dust inputs on the ecosystem. Sr and U-series isotopes are excellent tracers to identify sources of materials in an open system if the end-members have distinctive isotope signatures. These two isotope systems are particularly useful to trace the origin of atmospheric inputs into soils and to determine rates and timescales of soil formation. This study analyzes major elemental concentrations, Sr and U-series isotope ratios in highly depleted soils in the tropical volcanic island of Basse-Terre in French Guadeloupe to determine atmospheric input sources and identify key soil formation processes. We focus on three soil profiles (8 to 12 m thick) from the Bras-David, Moustique Petit-Bourg, and Deshaies watersheds; and on the adjacent rivers to these sites. Results have shown a significant depletion of U, Sr, and major elements in the deep profile (12 to 4 m) attributed to rapid chemical weathering. The top soil profiles (4 m to the surface) all show addition of elements such as Ca, Mg, U, and Sr due to atmospheric dust. More importantly, the topsoil profiles have distinct Sr and U-series isotope compositions from the deep soils. Sr and U-series isotope ratios of the top soils and sequential extraction fractions confirm that the sources of the dust are from the Saharan dessert, through long distance transport from Africa to the Caribbean region across the Atlantic Ocean. During the transport, some dust isotope signatures may also have been modified by local volcanic ashes and marine aerosols. Our study highlights that dusts and marine aerosols play important roles in element cycles and nutrient sources in the highly depleted surface soils of tropical oceanic islands.

Stratigraphic implications of trace element and strontium-isotope analyses of Kimmeridgian shell calcite from the Lower Saxony Basin, Germany

NASA Astrophysics Data System (ADS)

Zuo, Fanfan; Heimhofer, Ulrich; Huck, Stefan; Erbacher, Jochen; Bodin, Stephane

2017-04-01

Stratigraphic uncertainties due to the lack of open marine marker fossils (e.g. ammonites) hamper the precise age assignment and stratigraphic correlation of Kimmeridgian strata found in the Lower Saxony Basin of Northern Germany. Correlation of these deposits with the Jurassic standard ammonite zonation is still difficult, since the existing ostracod biostratigraphy is facies-controlled and of only limited stratigraphic precision. In this study, a chemostratigraphic approach has been chosen and biogenic shell material produced by brachiopods, oysters and lithiotids is evaluated for its reliability to act as proxy of the original Jurassic seawater strontium isotope composition. Low-Mg calcite shells have been collected from three stratigraphic sections accessible in open-cast quarries located in the Lower Saxony Basin of Northern Germany. In order to identify diagenetically altered shell calcite, trace element and stable isotope analysis of 227 calcite samples (oysters=101; brachiopods=60; Trichites=52) has been carried out. The geochemical results reveal that (1) concentration of different trace elements varies between the different groups of shell-forming organisms, which may be related to vital effects and (2) high strontium contents, low Mn and Fe contents and the lack of correlation between these elements indicate near-pristine calcite shells, and therefore shells are supposed to record the ambient sea water composition during the Late Jurassic. Strontium-isotope (87Sr/86Sr) analysis of diagenetically screened samples indicates an Early Kimmeridgian age of the studied deposits, which is in accordance with ostracod biostratigraphic data. An increasing trend in 87Sr/86Sr with stratigraphic height fits well with the global strontium-isotope curve. Besides, similar 87Sr/86Sr ratios derived from different organisms from a single stratigraphic level highlight the suitability of the shells for strontium-isotope stratigraphy. Despite the shallow-marine character of the studied deposits, no evidence for significant riverine influence on the strontium-isotope signature is observed. The new chemostratigraphic data will provide a more precise age assignment for Kimmeridgian strata in the Lower Saxony Basin and thus enable the establishment of a solid integrated stratigraphic scheme that can be used for correlation on both regional and global scale.

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.

Using laser micro mass spectrometry with the LAMMA-1000 instrument for monitoring relative elemental concentrations in vitrinite

USGS Publications Warehouse

Morelli, J.J.; Hercules, D.M.; Lyons, P.C.; Palmer, C.A.; Fletcher, J.D.

1988-01-01

The variation in relative elemental concentrations among a series of coal macerals belonging to the vitrinite maceral group was determined using laser micro mass spectrometry (LAMMS). Variations in Ba, Cr, Ga, Sr, Ti, and V concentrations among the coals were determined using the LAMM A-1000 instrument. LAMMS analysis is not limited to these elements; their selection illustrates the application of the technique. Ba, Cr, Ga, Sr, Ti, and V have minimal site-to-site variance in the vitrinite macerals of the studied coals as measured by LAMMS. The LAMMS data were compared with bulk elemental data obtained by instrumental neutron activation analysis (INAA) and D. C. arc optical emission spectroscopy (DCAS) in order to determine the reliability of the LAMMS data. The complex nature of the ionization phenomena in LAMMS and the lack of standards characterized on a microscale makes obtaining quantitative elemental data within the ionization microvolume difficult; however, we demonstrate that the relative variation of an element among vitrinites from different coal beds in the eastern United States can be observed using LAMMS in a "bulk" mode by accumulating signal intensities over several microareas of each vitrinite. Our studies indicate gross changes (greater than a factor of 2 to 5 depending on the element) can be monitored when the elemental concentration is significantly above the detection limit. "Bulk" mode analysis was conducted to evaluate the accuracy of future elemental LAMMS microanalyses. The primary advantage of LAMMS is the inherent spatial resolution, ~ 20 ??m for coal. Two different vitrite bands in the Lower Bakerstown coal bed (CLB-1) were analyzed. The analysis did not establish any certain concentration differences in Ba, Cr, Ga, Sr, Ti, and V between the two bands. ?? 1988 Springer-Verlag.

Magnetism and anisotropy of Ir5+ based double perovskites Sr2CoIrO6andSr2FeIrO6

NASA Astrophysics Data System (ADS)

Terzic, Jasminka; Yuan, S. J.; Song, W. H.; Aswartham, S.; Cao, G.

2015-03-01

We report on structural, thermodynamic and transport study of single-crystal double perovskites Sr2CoIrO6andSr2FeIrO6.TheisostructuralSr2CoIrO6andSr2FeIrO6 feature a cubic crystal structure with pentavalent Ir5+(5d4) which are anticipated to have J =0 singlet ground states in the strong spin-orbit coupling limit. Here we observe magnetic coupling between 5d and 3d (Co, Fe) elements, which result in antiferromagnetic order at high temperatures in both double perovskites. Of the two, Sr2CoIrO6 displays antiferromagnetic metallic behavior with a pronounced magnetic anisotropy; in sharp contrast, the isostructural Sr2FeIrO6 exhibits an antiferroamagnetic, insulating ground state without discernible magnetic anisotropy. The data will be discussed and presented with comparisons drawn with similar systems. This work was supported by NSF via Grant DMR 1265162.

Was Late Cretaceous Magmatism in the Northern Rocky Mountains Really Arc-Related?

NASA Astrophysics Data System (ADS)

Farmer, G.

2011-12-01

Calc-alkaline, Cretaceous magmatism affected much of the northern Rocky Mountain region in the western U.S. and is generally interpreted as continental arc magmatism despite the fact that it occurred as far east into the continental interior as the Late Cretaceous (75 Ma to 78 Ma) Sliderock Mountain volcanoplutonic complex in south-central Montana. Magmatism may have migrated so far inboard as a response to shallowing of the dip angle of underthrust oceanic lithosphere, but the exact sources, tectonic setting and trigger mechanisms for the Late Cretaceous igneous activity remain unclear. In this study, new trace element and Nd and Sr isotopic data, combined with existing age and major element data (duBray et al., 1998, USGS Prof. Paper 1602), from the most mafic lavas present at the Sliderock Mountain Volcano were used to further define the source regions of the Late Cretaceous magmatism. The most mafic lava flows are high K (~2-3 wt. % K2O), low Ti (< 1 wt. % TiO2), low Ni (< 20 ppm) basaltic andesites. Major element oxide contents for these rocks are only weakly correlated with increasing wt. % SiO2 on conventional Harker diagrams. All of the rocks are characterized by high LILE/HFSE ratios and high Pb contents (17-20 ppm), as expected for arc-related magmatism. The rocks also have high (La/Yb)N (7-20) but show decreasing (Dy/Yb)N with increasing wt.% SiO2, suggesting a cryptic role for amphibole fractionation during evolution of their parental magmas. Initial ɛNd values range from -19 to -29 but do not covary with rock bulk composition and as a result are unlikely to represent the result of interaction with local Archean continental crust. Initial 87Sr/86Sr, in contrast, vary over a restricted range from 0.7045 to 0.7065. The lowest 87Sr/86Sr correspond to samples with the highest Sr/Y (120-190). The low ɛNd values for the basaltic andesites suggest that if these volcanic rocks were ultimately derived from ultramafic mantle sources, melting must have occurred in Archean mantle lithosphere. Given the correlation between increasing Sr/Y and decreasing 87Sr/86Sr in the basaltic andesites, one possible trigger mechanism for lithospheric mantle melting is the influx into the thick Archean mantle keel of slab fluids (possibly including high Sr/Y slab melts) derived from oceanic lithosphere underthrust beneath this region in the Late Cretaceous. In this case, the Sliderock Mountain Volcano could, in fact, represent an example of continental interior "arc" magmatism.

Effect of Bioaccumulation of Cs and Sr Natural Isotopes on Foliar Structure and Plant Spectral Reflectance of Indian Mustard (Brassica juncea)

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

Maruthi Sridhar, Y.S.B.B.; Han, F.X.; Monts, D.L.

2008-07-01

The objectives of this study are: 1.) evaluate the capacity of Indian mustard (Brassica juncea) for uptake and accumulation of Cs and Sr natural isotopes; 2.) identify foliar structural and other physiological changes (biomass, relative water content, etc.) resulting from the accumulation of these two elements; and 3.) monitor Cs and Sr uptake and bioaccumulation process by spectral reflectance. Potted Indian mustard plants were exposed to different concentrations of Cs (50 and 600 ppm) and Sr (50 and 300 ppm) natural isotopes in solution form for 23 days. Bioaccumulation of Cs and Sr was found in the order of leavesmore » > stems > roots for both Cs- and Sr-treated plants. The highest leaf Sr accumulation is observed to be 2708 mg kg{sup -1}, and the highest leaf Cs accumulation is 12251 mg kg{sup -1}. High translocation efficiency for both elements is documented by shoot/root concentration ratios greater than one. Relative water content (RWC) of the plants showed a significant (p < 0.05) decrease in Cs-treated plants. Cs accumulation also affected the pigment concentration and internal structure of the leaf and the spectral characteristics of plants. Within the applied concentration range, Sr accumulation resulted in no significant changes in RWC, structural and spectral characteristics of mustard plants. Cs shoot concentration showed significant negative correlation with relative water content RWC (r = -0.88) and Normalized Difference Vegetation Index (NDVI) (r = -0.68) of plant shoots. The canopy spectral reflectance and NDVI analysis clearly revealed (p < 0.05) the stress caused by Cs accumulation. (authors)« less

Sleep-related crash characteristics: Implications for applying a fatigue definition to crash reports.

PubMed

Filtness, A J; Armstrong, K A; Watson, A; Smith, S S

2017-02-01

Sleep-related (SR) crashes are an endemic problem the world over. However, police officers report difficulties in identifying sleepiness as a crash contributing factor. One approach to improving the sensitivity of SR crash identification is by applying a proxy definition post hoc to crash reports. To identify the prominent characteristics of SR crashes and highlight the influence of proxy definitions, ten years of Queensland (Australia) police reports of crashes occurring in ≥100km/h speed zones were analysed. In Queensland, two approaches are routinely taken to identifying SR crashes. First, attending police officers identify crash causal factors; one possible option is 'fatigue/fell asleep'. Second, a proxy definition is applied to all crash reports. Those meeting the definition are considered SR and added to the police-reported SR crashes. Of the 65,204 vehicle operators involved in crashes 3449 were police-reported as SR. Analyses of these data found that male drivers aged 16-24 years within the first two years of unsupervised driving were most likely to have a SR crash. Collision with a stationary object was more likely in SR than in not-SR crashes. Using the proxy definition 9739 (14.9%) crashes were classified as SR. Using the proxy definition removes the findings that SR crashes are more likely to involve males and be of high severity. Additionally, proxy defined SR crashes are no less likely at intersections than not-SR crashes. When interpreting crash data it is important to understand the implications of SR identification because strategies aimed at reducing the road toll are informed by such data. Without the correct interpretation, funding could be misdirected. Improving sleepiness identification should be a priority in terms of both improvement to police and proxy reporting. Copyright © 2015 Elsevier Ltd. All rights reserved.

The chemical and isotopic differentiation of an epizonal magma body: Organ Needle pluton, New Mexico

USGS Publications Warehouse

Verplanck, P.L.; Farmer, G.L.; McCurry, M.; Mertzman, S.A.

1999-01-01

Major and trace element, and Nd and Sr isotopic compositions of whole rocks and mineral separates from the Oligocene, alkaline Organ Needle pluton (ONP), southern New Mexico, constrain models for the differentiation of the magma body parental to this compositionally zoned and layered epizonal intrusive body. The data reveal that the pluton is rimmed by lower ??(Nd) (~-5) and higher 87Sr/86Sr (~0.7085) syenitic rocks than those in its interior (??(Nd) ~ 2, 87Sr/86Sr ~0.7060) and that the bulk compositions of the marginal rocks become more felsic with decreasing structural depth. At the deepest exposed levels of the pluton, the ??(Nd)~-5 lithology is a compositionally heterogeneous inequigranular syenite. Modal, compositional and isotopic data from separates of rare earth element (REE)-bearing major and accesory mineral phases (hornblende, titanite, apatite, zircon) demonstrate that this decoupling of trace and major elements in the inequigranular syenite results from accumulation of light REE (LREE)-bearing minerals that were evidently separated from silicic magmas as the latter rose along the sides of the magma chamber. Chemical and isotopic data for microgranular mafic enclaves, as well as for restite xenoliths of Precambrian granite wall rock, indicate that the isotopic distinction between the marginal and interior facies of the ONP probably reflects assimilation of the wall rock by ??(Nd) ~-2 mafic magmas near the base of the magma system. Fractional crystallization and crystal liquid separation of the crystally contaminated magma at the base and along the margins of the chamber generated the highly silicic magmas that ultimately pooled at the chamber top.

Constraints On Fluid Evolution During Mid-Ocean Ridge Hydrothermal Circulation From Anhydrite Sampled by ODP Hole 1256D

NASA Astrophysics Data System (ADS)

Smith-Duque, C.; Teagle, D. A.; Alt, J. C.; Cooper, M. J.

2008-12-01

Anhydrite is potentially a useful mineral for recording the evolution of seawater-derived fluids during mid- ocean ridge hydrothermal circulation because it exhibits retrograde solubility, and hence may precipitate due to the heating of seawater or the sub-surface mixing of seawater with black smoker-like fluids. Here we provide new insights into the chemical and thermal evolution of seawater during hydrothermal circulation through analyses of anhydrite recovered from ODP Hole 1256D, the first complete penetration of intact upper oceanic crust down to gabbros. Previously, crustal anhydrite has been recovered only from Hole 504B. Measurements of 87Sr/86Sr, major element ratios, Rare Earth Elements and δ18O in anhydrite constrain the changing composition of fluids as they chemically interact with basalt. Anhydrite fills veins and pore-space in the lower lava sequences from ~530 to ~1000 meters sub- basement (msb), but is concentrated in the lava-dike transition (754 to 811 msb) and uppermost sheeted dikes. Although present in greater quantities than in Hole 504B, the amount of anhydrite recovered from the Site 1256 crust is low compared to that predicted by models of hydrothermal circulation (e.g., Sleep, 1991). Two distinct populations of anhydrite are indicated by measurements of 87Sr/86Sr suggesting different fluid evolution paths within Site 1256. One group of anhydrites have 87Sr/86Sr of 0.7070 to 0.7085, close to that of 15 Ma seawater (0.70878), suggesting that some fluids penetrate through the lavas and into the sheeted dikes with only minimal Sr-exchange with the host basalts. A second group, with low 87Sr/86Sr between 0.7048 and 0.7052, indicates precipitation from a fluid that has undergone far greater interaction with basalt. This range is close to that estimated from Sr-isotopic analyses of epidote for the Hole 1256D hydrothermal fluids (87Sr/86Sr ~0.705). Sr/Ca and 87Sr/86Sr indicate a similar relationship to that seen at ODP Hole 504B suggesting that Sr/Ca ratios reduce greatly during recharge before there is significant Sr exchange with the host basalts. δ18O measurements display an irregular trend with depth from +17‰ in the lower volcanics to +10‰ in the sheeted dikes suggesting an increase in precipitation temperatures from 105 to 211°C. One sample, from a chalcopyrite mineralized dike margin has a very light δ18O of +2.2‰ suggesting a temperature of ~408°, perhaps indicating that fluid was superheated following direct contact with the hot intrusive body. This sample also records low 87Sr/86Sr and high total REE.

Along and across arc geochemical variations in NW Central America: Evidence for involvement of lithospheric pyroxenite

NASA Astrophysics Data System (ADS)

Heydolph, Ken; Hoernle, Kaj; Hauff, Folkmar; Bogaard, Paul van den; Portnyagin, Maxim; Bindeman, Ilya; Garbe-Schönberg, Dieter

2012-05-01

The Central American Volcanic Arc (CAVA) has been the subject of intensive research over the past few years, leading to a variety of distinct models for the origin of CAVA lavas with various source components. We present a new model for the NW Central American Volcanic Arc based on a comprehensive new geochemical data set (major and trace element and Sr-Nd-Pb-Hf-O isotope ratios) of mafic volcanic front (VF), behind the volcanic front (BVF) and back-arc (BA) lava and tephra samples from NW Nicaragua, Honduras, El Salvador and Guatemala. Additionally we present data on subducting Cocos Plate sediments (from DSDP Leg 67 Sites 495 and 499) and igneous oceanic crust (from DSDP Leg 67 Site 495), and Guatemalan (Chortis Block) granitic and metamorphic continental basement. We observe systematic variations in trace element and isotopic compositions both along and across the arc. The data require at least three different endmembers for the volcanism in NW Central America. (1) The NW Nicaragua VF lavas require an endmember with very high Ba/(La, Th) and U/Th, relatively radiogenic Sr, Nd and Hf but unradiogenic Pb and low δ18O, reflecting a largely serpentinite-derived fluid/hydrous melt flux from the subducting slab into a depleted N-MORB type of mantle wedge. (2) The Guatemala VF and BVF mafic lavas require an enriched endmember with low Ba/(La, Th), U/Th, high δ18O and radiogenic Sr and Pb but unradiogenic Nd and Hf isotope ratios. Correlations of Hf with both Nd and Pb isotopic compositions are not consistent with this endmember being subducted sediments. Granitic samples from the Chiquimula Plutonic Complex in Guatemala have the appropriate isotopic composition to serve as this endmember, but the large amounts of assimilation required to explain the isotope data are not consistent with the basaltic compositions of the volcanic rocks. In addition, mixing regressions on Nd vs. Hf and the Sr and O isotope plots do not go through the data. Therefore, we propose that this endmember could represent pyroxenites in the lithosphere (mantle and possibly lower crust), derived from parental magmas for the plutonic rocks. (3) The Honduras and Caribbean BA lavas define an isotopically depleted endmember (with unradiogenic Sr but radiogenic Nd, Hf and Pb isotope ratios), having OIB-like major and trace element compositions (e.g. low Ba/(La, Th) and U/Th, high La/Yb). This endmember is possibly derived from melting of young, recycled oceanic crust in the asthenosphere upwelling in the back-arc. Mixing between these three endmember types of magmas can explain the observed systematic geochemical variations along and across the NW Central American Arc.

The Apollo 17 'melt sheet' - Chemistry, age and Rb/Sr systematics

NASA Technical Reports Server (NTRS)

Winzer, S. R.; Nava, D. F.; Schuhmann, S.; Philpotts, J. A.; Schuhmann, P. J.; Lum, R. K. L.; Lindstrom, M. M.; Lindstrom, D. J.

1977-01-01

Major, minor, and trace-element compositions, age data, and Rb/Sr systematics of Apollo 17 boulders have been compiled, and additional analyses performed on a norite breccia clast (77215) included in the Apollo 17, Station 7 boulder. The Apollo 17 boulders are found to be identical or nearly so in major, minor, and trace-element composition, suggesting that they all originated as an impact melt analogous to melt sheets found in larger terrestrial craters. The matrix dates (Ar-40/Ar-39) and Rb/Sr systematics available suggest that this impact melt formed by a single impact about 4 billion years ago. This impact excavated, shocked, brecciated, and melted norites, norite cumulates, and possibly anorthositic gabbros and dunites about 4.4 billion years old. The impact was likely a major one, possibly the Serenitatis basin-forming event.

SRXRF Study of Chemical Elements Content in the Atherosclerotic Plaque of Heart Vessels

NASA Astrophysics Data System (ADS)

Zhuravskaya, E. Ya.; Savchenko, T. I.; Chankina, O. V.; Polonskaya, Ya. V.; Chernyavskii, A. M.; Ragino, Yu. I.; Shcherbakova, L. V.

The SRXRF method has made it possible, for the first time, to determine the multielement composition in the atherosclerotic substrates of heart vessels after surgical interventions. The main advantage of the method is the possibility to analyze small samples without their destruction. As the amount of material to test is insufficient, we have developed a special technique for sample preparation. The concentrations of K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Zr, and Pb were measured in stable and unstable plaques. In all the samples studied, Ca is dominating, particularly, in the unstable plaque. No reliable difference was established for other elements measured. A high degree of the association of Ca with Fe, Zn and Sr has been revealed in the atherosclerotic plaques. Measurements were performed using SR from the VEPP-3 storage ring.

[Application of ICP-MS to Identify the Botanic Source of Characteristic Honey in South Yunnan].

PubMed

Wei, Yue; Chen, Fang; Wang, Yong; Chen, Lan-zhen; Zhang, Xue-wen; Wang, Yan-hui; Wu, Li-ming; Zhou, Qun

2016-01-01

By adopting inductively coupled plasma mass spectrometry (ICP-MS) combined with chemometric analysis technology, 23 kinds of minerals in four kinds of characteristic honey derived from Yunnan province were analyzed. The result showed that 21 kinds of mineral elements, namely Na, Mg, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Sb, Ba, Tl and Pb, have significant differences among different varieties of honey. The results of principal component analysis (PCA) showed that the cumulative variance contribution rate of the first four main components reached 77.74%, seven kinds of elements (Mg, Ca, Mn, Co, Sr, Cd, Ba) from the first main component contained most of the honey information. Through the stepwise discriminant analysis, seven kinds of elements (Mg, K, Ca, Cr, Mn, Sr, Pb) were filtered. out and used to establish the discriminant function model, and the correct classification rates of the proposed model reached 90% and 86.7%, respectively, which showed elements contents could be effectively indicators to discriminate the four kinds characteristic honey in southern Yunnan Province. In view of all the honey samples were harvested from apiaries located at south Yunnan Province where have similar climate, soil and other environment conditions, the differences of the mineral elements contents for the honey samples mainly due to their corresponding nectariferous plant. Therefore, it is feasible to identify honey botanical source through the differences of mineral elements.

Slab-derived components in the subcontinental lithospheric mantle beneath Chilean Patagonia: Geochemistry and Sr-Nd-Pb isotopes of mantle xenoliths and host basalt

NASA Astrophysics Data System (ADS)

Jalowitzki, Tiago; Gervasoni, Fernanda; Conceição, Rommulo V.; Orihashi, Yuji; Bertotto, Gustavo W.; Sumino, Hirochika; Schilling, Manuel E.; Nagao, Keisuke; Morata, Diego; Sylvester, Paul

2017-11-01

In subduction zones, ultramafic xenoliths hosted in alkaline basalts can yield significant information about the role of potential slab-derived components in the subcontinental lithospheric mantle (SCLM). Chemical and isotopic heterogeneities in such xenoliths are usually interpreted to reflect melt extraction followed by metasomatic re-enrichment. Here we report new whole-rock major, trace element and isotopic (Sr-Nd-Pb) data for a Proterozoic suite of 17 anhydrous spinel-lherzolites and Eocene (new K-Ar data) host alkaline basalt found near Coyhaique ( 46°S), Aysén Region, Chile. These Patagonian nodules are located in a current back-arc position, 100 km east of the present day volcanic arc and 320 km from the Chile Trench. The mantle xenoliths consist of coarse- to medium-grained spinel-lherzolites with trace element compositions characteristic of a subduction zone setting, such as pronounced negative Nb, Ta and Ti anomalies coupled with significant enrichment of LILEs (e.g., U) and chalcophile elements (W, Pb and Sn). Most of them are characterized by flat to depleted light-rare earth element (LREE) patterns (Ce/YbN = 0.6-1.1) coupled with less radiogenic Sr-Pb (87Sr/86Sr = 0.702422-0.703479; 206Pb/204Pb = 18.212-18.539) and more radiogenic Nd isotopic compositions (143Nd/144Nd = 0.512994-0.513242), similar to the depleted mantle component (DMM or PREMA). In contrast, samples with slight LREE enrichment (Ce/YbN = 1.3-1.8) show more radiogenic Sr-Pb (87Sr/86Sr = 0.703791-0.704239; 206Pb/204Pb = 18.572-18.703) and less radiogenic Nd isotopic compositions (143Nd/144Nd = 0.512859-0.512934), similar to the EM-2 reservoir. These new geochemical and isotope data suggest that the Coyhaique spinel-lherzolites are derived from a heterogeneous SCLM resulting from mixing between a depleted mantle component and up to 10% of slab-derived components. The enriched component added to the SCLM represents variable extents of melts of both subducted Chile Trench sediments and modified oceanic crust throughout the initial stages of the Farallón-Aluk ridge collision during Paleocene to Eocene time. However, based on the tectonic evolution of southern South America, we cannot exclude the influence of long-lived subduction events beneath south Patagonia. Although we believe that the studied samples were brought to the surface in this geodynamic context, there is no evidence that ocean island basalt (OIB)-like melts related to the Farallón-Aluk asthenospheric slab window affected the peridotite composition. The host alkaline basalt is a single unit with a HIMU-like OIB signature characterized by marked positive Nb-Ta anomalies coupled with negative anomalies in highly incompatible and fluid-mobile elements (Rb, K, Pb, and Sr). The compositional similarity between the HIMU-like OIB mantle source and the host basalt is also evident from trace element ratios [(Ba-Th-K-La-Zr)/Nb] as well as by the low 87Sr/86Sri (0.703039-0.703058) and relatively high 143Nd/144Ndi (0.512880-0.512874) and 206Pb/204Pb (19.333-19.389) isotopic ratios. The low 206Pb/204Pb ratios compared to end-member HIMU lavas (e.g., Sta. Helena and the Cook-Austral Islands) suggest that this region was modified by processes associated with a prolonged period of subduction related to the Andean orogenesis and the recycling of several oceanic plates beneath the continent, following the Mesozoic breakup of Gondwana or an even older subduction-related event with young recycling ages (< 2 Ga).

Origins of diamond-forming fluids: An isotopic and trace element study of diamonds and silicates from diamondiferous xenoliths

NASA Astrophysics Data System (ADS)

Laiginhas, Fernando; Pearson, D. Graham; McNeill, John; Gurney, John; Nowell, Geoff; Ottley, Chris

2010-05-01

While there is increasing understanding of the age of formation and nature of "gem" diamonds, significant debate revolves around the nature of the fluids/melts from which they form. Stable C and N isotopes have been shown to be highly variable and yet the role of subduction-related fluids remains strongly debated. Recent studies on fibrous diamonds have yielded new trace and major element data (e.g., Weiss et al., 2009) that, together with new radiogenic isotope data (Klein BenDavid et al., 2010) indicate such diamonds grow from fluids that comprise mixtures of hydrous silicic, hydrous saline and carbonatitic fluids, derived from different source components of asthenospheric and lithospheric origin. However, until now such data has been lacking from gem diamonds. Using a new laser-based technique (McNeill et al., 2009), we have analysed a suite of diamonds plus co-existing host silicates from several diamondiferous xenoliths (6 harzburgites, 1 eclogite) from the Finsch and Newlands kimberlites in order to try to understand the fluid compositions that produce gem diamonds and better understand their effects of their mantle wall rocks. Diamonds from the xenoliths show a wide variety of trace element enrichment levels. While the eclogitic diamond shows similar trace element systematics to some of the harzburgitic diamonds there are significant differences within the harzburgitic diamonds from different xenoliths, with those from Finsch being significantly enriched in Ba, Sr and Pb relative to other elements. Nd isotope data on the host silicates is variable and dominantly unradiogenic, indicative of long-term enrichment typically associated with the source of some diamond-forming fluids. We will present Sr isotopic data on host silicates and diamond fluids to constrain whether the "gem" diamonds require the complex sources of fluids that characterise the growth of fibrous diamonds. 1) Y. Weiss, R. Kessel, W.L. Griffin, I. Kiflawi, O. Klein-BenDavid, D.R. Bell, J.W. Harris and O. Navon (2009). A new model for the evolution of diamond-forming fluids: Evidence from microinclusion-bearing diamonds from Kankan, Guinea. Lithos 112, Supp. 2: 660-674. 2) O. Klein-BenDavid, D.G. Pearson, G.M. Nowell, C. Ottley, J.C.R. McNeill, P. Cartigny (2010). Mixed fluid sources involved in diamond growth constrained by Sr-Nd-Pb-C-N isotopes and trace elements. EPSL 289, 1-2: 123-133. 3) J. McNeill, D.G. Pearson, O. Klein-BenDavid, G.M. Nowell, C.J. Ottley and I. Chinn (2009). Quantitative analysis of trace element concentrations in some gem-quality diamonds. J. Phys.: Condens. Matter 21: 364207 (13pp).

Body distribution of trace elements in black-tailed gulls from Rishiri Island, Japan: age-dependent accumulation and transfer to feathers and eggs.

PubMed

Agusa, Tetsuro; Matsumoto, Taro; Ikemoto, Tokutaka; Anan, Yasumi; Kubota, Reiji; Yasunaga, Genta; Kunito, Takashi; Tanabe, Shinsuke; Ogi, Haruo; Shibata, Yasuyuki

2005-09-01

Body distribution and maternal transfer of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl, and Pb) to eggs were examined in black-tailed gulls (Larus crassirostris), which were culled in Rishiri Island, Hokkaido Prefecture, Japan. Manganese, Cu, Rb, Mo, and Cd showed the highest levels in liver and kidney, Ag, Sb, and Hg in feather, and V, Sr, and Pb in bone. Maternal transfer rates of trace elements ranged from 0.8% (Cd) to as much as 65% (Tl) of maternal body burden. Large amounts of Sr, Ba, and Tl were transferred to the eggs, though maternal transfer rates of V, Cd, Hg, and Pb were substantially low. It also was observed that Rb, Sr, Cd, Cs, and Ba hardly were excreted into feathers. Concentrations of Co in liver, Ba in liver and kidney, and Mo in liver increased significantly with age, whereas Se in bone and kidney, Hg in kidney, and Cr in feather decreased with age in the known-aged black-tailed gulls (2-20 years old). It also was suggested that feathers might be useful to estimate contamination status of trace elements in birds, especially for Hg on a population basis, although the utility is limited on an individual basis for the black-tailed gulls. To our knowledge, this is the first report on the maternal transfer rate of multielements and also on the usefulness of feathers to estimate contamination status of Hg in birds on a population basis.

Paleoenvironmental signals and paleoclimatic condition of the Early Maastrichtian oil shales from Central Eastern Desert, Egypt

NASA Astrophysics Data System (ADS)

Fathy, Douaa; Wagreich, Michael; Zaki, Rafat; Mohamed, Ramadan S. A.

2016-04-01

Early Maastrichtian oil shales are hosted in the Duwi Formation of the Central Eastern Desert, Egypt. The examined member represents up to 20% of the total Duwi Formation. This interval is mainly composed of siliciclastic facies, phosphorites facies and carbonate facies. Oil shales microfacies is mainly composed of smectite, kaolinite, calcite, fluorapatite, quartz and pyrite. They are enriched in a number of major elements and trace metals in particular Ca, P, V, Ni, Cr, Sr, Zn, Mo, Nb, U and Y compared to the post-Archaean Australian shale (PAAS). Chondrite-normalized REEs patterns of oil shales for the studied area display light rare earth elements enrichment relatively to heavy rare earth elements with negative Ce/Ce* and Eu/Eu* anomalies. The most remarkable indicators for redox conditions are enrichments of V, Mo, Ni, Cr, U content and depletion of Mn content. Besides, V/V+Ni, V/Ni, U/Th, Ni/Co, authigentic uranium ratios with presence of framboidal shape of pyrite and its size are reflecting the deposition of these shales under marine anoxic to euxinic environmental conditions. Additionally, the ratio of Strontium (Sr) to Barium (Ba) Sr/Ba reflected highly saline water during deposition. Elemental ratios critical to paleoclimate and paleoweathering (Rb /Sr, Al2O3/TiO2), CIA values, binary diagram between (Al2O3+K2O+Na2O) and SiO2 and types of clay minerals dominated reflect warm to humid climate conditions prevailing during the accumulation of these organic-rich petroleum source rocks.

Alkali trace elements in Gale crater, Mars, with ChemCam: Calibration update and geological implications

NASA Astrophysics Data System (ADS)

Payré, V.; Fabre, C.; Cousin, A.; Sautter, V.; Wiens, R. C.; Forni, O.; Gasnault, O.; Mangold, N.; Meslin, P.-Y.; Lasue, J.; Ollila, A.; Rapin, W.; Maurice, S.; Nachon, M.; Le Deit, L.; Lanza, N.; Clegg, S.

2017-03-01

The Chemistry Camera (ChemCam) instrument onboard Curiosity can detect minor and trace elements such as lithium, strontium, rubidium, and barium. Their abundances can provide some insights about Mars' magmatic history and sedimentary processes. We focus on developing new quantitative models for these elements by using a new laboratory database (more than 400 samples) that displays diverse compositions that are more relevant for Gale crater than the previous ChemCam database. These models are based on univariate calibration curves. For each element, the best model is selected depending on the results obtained by using the ChemCam calibration targets onboard Curiosity. New quantifications of Li, Sr, Rb, and Ba in Gale samples have been obtained for the first 1000 Martian days. Comparing these data in alkaline and magnesian rocks with the felsic and mafic clasts from the Martian meteorite NWA7533—from approximately the same geologic period—we observe a similar behavior: Sr, Rb, and Ba are more concentrated in soluble- and incompatible-element-rich mineral phases (Si, Al, and alkali-rich). Correlations between these trace elements and potassium in materials analyzed by ChemCam reveal a strong affinity with K-bearing phases such as feldspars, K-phyllosilicates, and potentially micas in igneous and sedimentary rocks. However, lithium is found in comparable abundances in alkali-rich and magnesium-rich Gale rocks. This very soluble element can be associated with both alkali and Mg-Fe phases such as pyroxene and feldspar. These observations of Li, Sr, Rb, and Ba mineralogical associations highlight their substitution with potassium and their incompatibility in magmatic melts.

Concentrations of trace elements in American alligators (Alligator mississippiensis) from Florida, USA.

PubMed

Horai, Sawako; Itai, Takaaki; Noguchi, Takako; Yasuda, Yusuke; Adachi, Haruki; Hyobu, Yuika; Riyadi, Adi S; Boggs, Ashley S P; Lowers, Russell; Guillette, Louis J; Tanabe, Shinsuke

2014-08-01

Concentrations of 28 trace elements (Li, Mg, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Tl, Hg, Pb, and Bi) in the livers of juvenile and adult American alligators inhabiting two central Florida lakes, Lake Apopka (LA), and Lake Woodruff National Wildlife Refuge (LW) and one lagoon population located in Merritt Island National Wildlife Refuge (MINWR; NASA), were determined. In juveniles from MINWR, concentrations of nine elements (Li, Fe, Ni, Sr, In, Sb, Hg, Pb and Bi) were significantly higher, whereas six elements (V, Fe, As, Sr, Hg and Bi) were elevated in adults (p<0.05) obtained from MINWR. Significant enrichment of some trace elements in adults, relative to juveniles, was observed at all three sampling areas. Specifically, Fe, Pb and Hg were significantly elevated in adults when compared to juveniles, suggesting age-dependent accumulation of these elements. Further, As, Se and Sn showed the same trend but only in animals collected from MINWR. Mean Fe concentrations in the livers of adults from LA, LW and MINWR were 1770 μg g(-1) DW, 3690 μg g(-1) DW and 5250 μg g(-1) DW, respectively. More than half of the adult specimens from LW and MINWR exhibited elevated hepatic Fe concentrations that exceed the threshold value for toxic effects in donkey, red deer and human. These results prompted us to express our concern on possible exposure and health effects in American alligators by some trace elements derived from NASA activities. Copyright © 2014 Elsevier Ltd. All rights reserved.

Plume-related mantle source of super-large rare metal deposits from the Lovozero and Khibina massifs on the Kola Peninsula, Eastern part of Baltic Shield: Sr, Nd and Hf isotope systematics

NASA Astrophysics Data System (ADS)

Kogarko, L. N.; Lahaye, Y.; Brey, G. P.

2010-03-01

The two world’s largest complexes of highly alkaline nepheline syenites and related rare metal loparite and eudialyte deposits, the Khibina and Lovozero massifs, occur in the central part of the Kola Peninsula. We measured for the first time in situ the trace element concentrations and the Sr, Nd and Hf isotope ratios by LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometer) in loparite, eudialyte an in some other pegmatitic minerals. The results are in aggreement with the whole rock Sr and Nd isotope which suggests the formation of these superlarge rare metal deposits in a magmatic closed system. The initial Hf, Sr, Nd isotope ratios are similar to the isotopic signatures of OIB indicating depleted mantle as a source. This leads to the suggestion that the origin of these gigantic alkaline intrusions is connected to a deep seated mantle source—possibly to a lower mantle plume. The required combination of a depleted mantle and high rare metal enrichment in the source can be explained by the input of incompatible elements by metasomatising melts/fluids into the zones of alkaline magma generation shortly before the partial melting event (to avoid ingrowth of radiogenic isotopes). The minerals belovite and pyrochlore from the pegmatites are abnormally high in 87Sr /86Sr ratios. This may be explained by closed system isotope evolution as a result of a significant increase in Rb/Sr during the evolution of the peralkaline magma.

Trace element and isotopic composition of apatite in carbonatites from the Blue River area (British Columbia, Canada) and mineralogy of associated silicate rocks

NASA Astrophysics Data System (ADS)

Mitchell, Roger; Chudy, Thomas; McFarlane, Christopher R. M.; Wu, Fu-Yuan

2017-08-01

Apatites from the Verity, Fir, Gum, Howard Creek and Felix carbonatites of the Blue River (British Columbia, Canada) area have been investigated with respect to their paragenesis, cathodoluminescence, trace element and Sr-Nd isotopic composition. Although all of the Blue River carbonatites were emplaced as sills prior to amphibolite grade metamorphism and have undergone deformation, in many instances magmatic textures and mineralogy are retained. Attempts to constrain the U-Pb age of the carbonatites by SIMS, TIMS and LA-ICP-MS studies of zircon and titanite were inconclusive as all samples investigated have experienced significant Pb loss during metamorphism. The carbonatites are associated with undersaturated calcite-titanite amphibole nepheline syenite only at Howard Creek although most contain clasts of disaggregated phoscorite-like rocks. Apatite from each intrusion is characterized by distinct, but wide ranges, in trace element composition. The Sr and Nd isotopic compositions define an array on a 87Sr/86Sr vs²Nd diagram at 350 Ma indicating derivation from depleted sub-lithospheric mantle. This array could reflect mixing of Sr and Nd derived from HIMU and EM1 mantle sources, and implies that depleted mantle underlies the Canadian Cordillera. Although individual occurrences of carbonatites in the Blue River region are mineralogically and geochemically similar they are not identical and thus cannot be considered as rocks formed from a single batch of parental magma at the same stage of magmatic evolution. However, a common origin is highly probable. The variations in the trace element content and isotopic composition of apatite from each occurrence suggest that each carbonatite represents a combination of derivation of the parental magma(s) from mineralogically and isotopically heterogeneous depleted mantle sources coupled with different stages of limited differentiation and mixing of these magmas. We do not consider these carbonatites as primary direct partial melts of the sub-lithospheric mantle which have ascended from the asthenosphere without modification of their composition.

IsoMark - a comprehensive assessment of the potential of isotopes in hard parts of freshwater fish to determine origin and migratory patterns using LA-(MC)-ICP-MS

NASA Astrophysics Data System (ADS)

Zitek, Andreas; Irrgeher, Johanna; Sturm, Monika; Brunner, Marion; Dillinger, Benno; Prohaska, Thomas

2010-05-01

The ‘IsoMark' project focuses for the first time on the comprehensive investigation of microchemical information (elemental fingerprint of Ca, Sr, Na, Ba, Mg; isotopic fingerprint of Sr, Ca, and additionally of C and O) in different hard parts of several typical European freshwater fish species like brown trout (Salmo trutta f.f., L.), European grayling (Thymallus thymallus, L.) or nase (Chondrostoma nasus, L.) and the barbel (Barbus barbus, L.). Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used as major technique for the direct in situ analysis of trace elements and isotopes, whereby the employment of a multiple collector - inductively coupled plasma - mass spectrometer (MC-ICP-MS) enables high precise isotope ratio analysis of such sample matrices due to its simultaneous detection capabilities. Microchemical patterns in hard parts of farmed and wild fish are analysed resulting in natural site specific elemental and isotopic signatures. Within a pilot study the potential to discriminate between wild and hatchery trout by chronological microchemical patterns of different otolith regions in relation to site specific water chemistry was documented. 100% accuracy of classification of fish to life stage specific habitats and therefore to their origin was achieved by the elemental ratios 88Sr/43Ca, 23Na/43Ca and the isotope ratio of 87Sr/86Sr. Clear differences in otolith chemistry were found, when fish experienced different geological units or specific environmental situations (e.g. groundwater) in hatcheries during a certain period of their life. These results proved the concept that natural microchemical patterns in hard parts linked to specific life stages of fish represent a valuable tool for a wide variety of ecological questions, e.g. discriminating wild and hatchery fish without the necessity of inducing any other artificial mark, or studying natural migration phenomena on small spatial scales in freshwater systems within geologically diverse river catchments.

Probing Intracellular Element Concentration Changes during Neutrophil Extracellular Trap Formation Using Synchrotron Radiation Based X-Ray Fluorescence

PubMed Central

Niemiec, Maria J.; Laforce, Brecht; Garrevoet, Jan; Vergucht, Eva; De Rycke, Riet; Cloetens, Peter; Urban, Constantin F.; Vincze, Laszlo

2016-01-01

High pressure frozen (HPF), cryo-substituted microtome sections of 2 μm thickness containing human neutrophils (white blood cells) were analyzed using synchrotron radiation based X-ray fluorescence (SR nano-XRF) at a spatial resolution of 50 nm. Besides neutrophils from a control culture, we also analyzed neutrophils stimulated for 1–2 h with phorbol myristate acetate (PMA), a substance inducing the formation of so-called Neutrophil Extracellular Traps (or NETs), a defense system again pathogens possibly involving proteins with metal chelating properties. In order to gain insight in metal transport during this process, precise local evaluation of elemental content was performed reaching limits of detection (LODs) of 1 ppb. Mean weight fractions within entire neutrophils, their nuclei and cytoplasms were determined for the three main elements P, S and Cl, but also for the 12 following trace elements: K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Se, Br, Sr and Pb. Statistical analysis, including linear regression provided objective analysis and a measure for concentration changes. The nearly linear Ca and Cl concentration changes in neutrophils could be explained by already known phenomena such as the induction of Ca channels and the uptake of Cl under activation of NET forming neutrophils. Linear concentration changes were also found for P, S, K, Mn, Fe, Co and Se. The observed linear concentration increase for Mn could be related to scavenging of this metal from the pathogen by means of the neutrophil protein calprotectin, whereas the concentration increase of Se may be related to its antioxidant function protecting neutrophils from the reactive oxygen species they produce against pathogens. We emphasize synchrotron radiation based nanoscopic X-ray fluorescence as an enabling analytical technique to study changing (trace) element concentrations throughout cellular processes, provided accurate sample preparation and data-analysis. PMID:27812122

Composition and Elution Behavior of Various Elements from Printed Circuit Boards, Cathode-ray Tube Glass, and Liquid-crystal Displays in Waste Consumer Electronics.

PubMed

Inaba, Kazuho; Murata, Tomoyoshi; Yamamura, Shigeki; Nagano, Masaaki; Iwasaki, Kazuhiro; Nakajima, Daisuke; Takigami, Hidetaka

2018-01-01

The contents and elution behavior of metals in consumer electronics parts were determined so as to understand their maximum environmental risk. Elements contained most in printed-circuit boards were Cu, Si, Br, Ca, Al, Sn, Pb, Sb, Ba, Fe, Ni, Ti, and Zn; in cathode-ray tube glass were Si, Pb, Ba, Sr, Zn, Zr, Ca, and Sb; in arsenic contained liquid-crystal displays were Si, Ca, Sr, Ba, As, and Fe; and in antimony contained liquid-crystal displays were Si, Ba, Ca, Sb, Sr, Fe, and Sn. The elements eluted most from printed-circuit boards were Zn, Pb, and Cu; from cathode-ray tube glass were Pb, Zn, B, Ba, and Si; and from liquid-crystal displays were B and Si, and the toxic As and Sb. The amount eluted was greatest at acidic pH. It was revealed that officially recommended 6-h-shaking with a pure water test was insufficient to understand the real environmental risk of waste electronics.

Aqueous fluids and sedimentary melts as agents for mantle wedge metasomatism, as inferred from peridotite xenoliths at Pinatubo and Iraya volcanoes, Luzon arc, Philippines

NASA Astrophysics Data System (ADS)

Yoshikawa, Masako; Tamura, Akihiro; Arai, Shoji; Kawamoto, Tatsuhiko; Payot, Betchaida D.; Rivera, Danikko John; Bariso, Ericson B.; Mirabueno, Ma. Hannah T.; Okuno, Mitsuru; Kobayashi, Tetsuo

2016-10-01

Mantle xenoliths entrained in subduction-zone magmas often record metasomatic signature of the mantle wedge. Such xenoliths occur in magmas from Iraya and Pinatubo volcanoes, located at the volcanic front of the Luzon arc in the Philippines. In this study, we present the major element compositions of the main minerals, trace element abundances in pyroxenes and amphiboles, and Nd-Sr isotopic compositions of amphiboles in the peridotite xenoliths from Pinatubo volcano. The data indicate enrichment in fluid-mobile elements, such as Rb, Ba, U, Pb, and Sr, and Nd-Sr isotopic ratios relative to those of mantle. The results are considered in terms of mixing of asthenospheric mantle and subducting oceanic crustal components. The enrichments observed in the Pinatubo mantle xenoliths are much less pronounced than those reported for the Iraya mantle xenoliths. This disparity suggests differences in the metasomatic agents contributing to the two suites; i.e., aqueous fluids infiltrated the mantle wedge beneath the Pinatubo volcano, whereas aqueous fluids and sediment-derived melts infiltrated the mantle wedge beneath the Iraya volcano.

On the distribution of trace element concentrations in multiple bone elements in 10 Danish medieval and post-medieval individuals.

PubMed

Lund Rasmussen, Kaare; Skytte, Lilian; D'imporzano, Paolo; Orla Thomsen, Per; Søvsø, Morten; Lier Boldsen, Jesper

2017-01-01

The differences in trace element concentrations among 19 different bone elements procured from 10 archaeologically derived human skeletons have been investigated. The 10 individuals are dated archaeologically and some by radiocarbon dating to the medieval and post-medieval period, an interval from ca. AD 1150 to ca. AD 1810. This study is relevant for two reasons. First, most archaeometric studies analyze only one bone sample from each individual; so to what degree are the bones in the human body equal in trace element chemistry? Second, differences in turnover time of the bone elements makes the cortical tissues record the trace element concentrations in equilibrium with the blood stream over a longer time earlier in life than the trabecular. Therefore, any differences in trace element concentrations between the bone elements can yield what can be termed a chemical life history of the individual, revealing changes in diet, provenance, or medication throughout life. Thorough decontamination and strict exclusion of non-viable data has secured a dataset of high quality. The measurements were carried out using Inductively Coupled Plasma Mass Spectrometry (for Fe, Mn, Al, Ca, Mg, Na, Ba, Sr, Zn, Pb and As) and Cold Vapor Atomic Absorption Spectroscopy (for Hg) on ca. 20 mg samples. Twelve major and trace elements have been measured on 19 bone elements from 10 different individuals interred at five cemeteries widely distributed in medieval and renaissance Denmark. The ranges of the concentrations of elements were: Na (2240-5660 µg g -1 ), Mg (440-2490 µg g -1 ), Al (9-2030 µg g -1 ), Ca (22-36 wt. %), Mn (5-11450 µg g -1 ), Fe (32-41850 µg g -1 ), Zn (69-2610 µg g -1 ), As (0.4-120 µg g -1 ), Sr (101-815 µg g -1 ), Ba (8-880 µg g -1 ), Hg (7-78730 ng g -1 ), and Pb (0.8-426 µg g -1 ). It is found that excess As is mainly of diagenetic origin. The results support that Ba and Sr concentrations are effective provenance or dietary indicators. Migrating behavior or changes in diet have been observed in four individuals; non-migratory or non-changing diet in six out of the 10 individuals studied. From the two most mobile (most changing diet) individuals in the study, it is deduced that the fastest turnover is seen in the trabecular tissues of the long bones and the hands and the feet, and that these bone elements have higher turnover rates than centrally placed trabecular bone tissue, such as from the ilium or the spine. Comparing Sr and published bone turnover times, it is concluded that the differences seen in Sr concentrations are not caused by diagenesis, but by changes of diet or provenance. Finally, it is concluded that there can be two viable interpretations of the Pb concentrations, which can either be seen as an indicator for social class or a temporal development of increased Pb exposure over the centuries. © 2016 Wiley Periodicals, Inc.

Elemental and isotopic (C, O, Sr, Nd) compositions of Late Paleozoic carbonated eclogite and marble from the SW Tianshan UHP belt, NW China: Implications for deep carbon cycle

NASA Astrophysics Data System (ADS)

Zhu, Jianjiang; Zhang, Lifei; Lü, Zeng; Bader, Thomas

2018-03-01

Subduction zones are important for understanding of the global carbon cycle from the surface to deep part of the mantle. The processes involved the metamorphism of carbonate-bearing rocks largely control the fate of carbon and contribute to local carbon isotopic heterogeneities of the mantle. In this study, we present petrological and geochemical results for marbles and carbonated eclogites in the Southwestern Tianshan UHP belt, NW China. Marbles are interlayered with coesite-bearing pelitic schists, and have Sr-Nd isotopic values (εNd (T=320Ma) = -3.7 to -8.9, 87Sr/86Sr (i) = 0.7084-0.7089), typical of marine carbonates. The marbles have dispersed low δ18OVSMOW values (ranging from 14 to 29‰) and unaffected carbon isotope (δ13CVPDB = -0.2-3.6‰), possibly due to infiltration of external H2O-rich fluids. Recycling of these marbles into mantle may play a key role in the carbon budget and contributed to the mantle carbon isotope heterogeneity. The carbonated eclogites have high Sr isotopic compositions (87Sr/86Sr (i) = 0.7077-0.7082) and positive εNd (T = 320 Ma) values (from 7.6 to 8.2), indicative of strong seafloor alteration of their protolith. The carbonates in the carbonated eclogites are mainly dolomite (Fe# = 12-43, Fe# = Fe2+/(Fe2+ + Mg)) that were added into oceanic basalts during seafloor alteration and experienced calcite - dolomite - magnesite transformation during the subduction metamorphic process. The uniformly low δ18O values (∼11.44‰) of carbonates in the carbontaed eclogites can be explained by closed-system equilibrium between carbonate and silicate minerals. The low δ13C values (from -3.3 to -7.7‰) of the carbonated eclogites most likely reflect contribution from organic carbon. Recycling of these carbonated eclogites with C isotope similar to typical mantle reservoirs into mantle may have little effect on the mantle carbon isotope heterogeneity.

Methods for separating oxygen from oxygen-containing gases

DOEpatents

Mackay, Richard; Schwartz, Michael; Sammells, Anthony F.

2000-01-01

This invention provides mixed conducting metal oxides particularly useful for the manufacture of catalytic membranes for gas-phase oxygen separation processes. The materials of this invention have the general formula: A.sub.x A'.sub.x A".sub.2-(x+x') B.sub.y B'.sub.y B".sub.2-(y+y') O.sub.5+z ; where x and x' are greater than 0; y and y' are greater than 0; x+x' is less than or equal to 2; y+y' is less than or equal to 2; z is a number that makes the metal oxide charge neutral; A is an element selected from the f block lanthanide elements; A' is an element selected from Be, Mg, Ca, Sr, Ba and Ra; A" is an element selected from the f block lanthanides or Be, Mg, Ca, Sr, Ba and Ra; B is an element selected from the group consisting of Al, Ga, In or mixtures thereof; and B' and B" are different elements and are independently selected from the group of elements Mg or the d-block transition elements. The invention also provides methods for oxygen separation and oxygen enrichment of oxygen deficient gases which employ mixed conducting metal oxides of the above formula. Examples of the materials used for the preparation of the membrane include A.sub.x Sr.sub.x' B.sub.y Fe.sub.y' Co.sub.2-(y+y') O.sub.5+z, where x is about 0.3 to about 0.5, x' is about 1.5 to about 1.7, y is 0.6, y' is between about 1.0 and 1.4 and B is Ga or Al.

Stable Isotopes of Sr and Pb as Tracers of Sources of Airborne Particulate Matter in Kyrgyzstan

EPA Science Inventory

ConclusionsElemental concentrations were higher at the LIDAR site compared to the Bishkek site. Also, concentrations were higher during dust than non-dust events at both sites.The Sr isotopic ratios suggest dust from another region, such as from Western China, Africa, or Middle E...

Reconstructing Ancient Egyptian Diet through Bone Elemental Analysis Using LIBS (Qubbet el Hawa Cemetery)

PubMed Central

Al-Khafif, Ghada Darwish; El-Banna, Rokia

2015-01-01

One of the most important advantages of LIBS that make it suitable for the analysis of archeological materials is that it is a quasi-nondestructive technique. Archeological mandibles excavated from Qubbet el Hawa Cemetery, Aswan, were subjected to elemental analysis in order to reconstruct the dietary patterns of the middle class of the Aswan population throughout three successive eras: the First Intermediate Period (FIP), the Middle Kingdom (MK), and the Second Intermediate Period (SIP). The bone Sr/Ca and Ba/Ca ratios were significantly correlated, so the Sr/Ca ratios are considered to represent the ante-mortem values. It was suggested that the significantly low FIP Sr/Ca compared to that of both the MK and the SIP was attributed to the consumption of unusual sorts of food and imported cereals during years of famine, while the MK Sr/Ca was considered to represent the amelioration of climatic, social, economic, and political conditions in this era of state socialism. The SIP Sr/Ca, which is nearly the same as that of the MK, was considered to be the reflection of the continuity of the individualism respect and state socialism and a reflection of agriculture conditions amelioration under the reign of the 17th Dynasty in Upper Egypt. PMID:26345727

Trace element geochemistry of Archean volcanic rocks

NASA Technical Reports Server (NTRS)

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

1974-01-01

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

Monitoring of trace element atmospheric deposition using dry and wet moss bags: accumulation capacity versus exposure time.

PubMed

Anicić, M; Tomasević, M; Tasić, M; Rajsić, S; Popović, A; Frontasyeva, M V; Lierhagen, S; Steinnes, E

2009-11-15

To clarify the peculiarities of trace element accumulation in moss bags technique (active biomonitoring), samples of the moss Sphagnum girgensohnii Rusow were exposed in bags with and without irrigation for 15 days up to 5 months consequently in the semi-urban area of Belgrade (Serbia) starting from July 2007. The accumulation capacity for 49 elements determined by ICP-MS in wet and dry moss bags was compared. The concentration of some elements, i.e. Al, V, Cr, Fe, Zn, As, Se, Sr, Pb, and Sm increased continuously with exposure time in both dry and wet moss bags, whereas concentration of Na, Cl, K, Mn, Rb, Cs, and Ta decreased. Irrigation of moss resulted in a higher accumulation capacity for most of the elements, especially for Cr, Zn, As, Se, Br, and Sr. Principal component analysis was performed on the datasets of element concentrations in wet and dry moss bags for source identification. Results of the factor analysis were similar but not identical in the two cases due to possible differences in element accumulation mechanisms.

Six-Month Changes in Spirituality and Religiousness in Alcoholics Predict Drinking Outcomes at Nine Months*

PubMed Central

Robinson, Elizabeth A. R.; Krentzman, Amy R.; Webb, Jon R.; Brower, Kirk J.

2011-01-01

Objective: Although spiritual change is hypothesized to contribute to recovery from alcohol dependence, few studies have used prospective data to investigate this hypothesis. Prior studies have also been limited to treatment-seeking and Alcoholics Anonymous (AA) samples. This study included alcohol-dependent individuals, both in treatment and not, to investigate the effect of spiritual and religious (SR) change on subsequent drinking outcomes, independent of AA involvement. Method: Alcoholics (N = 364) were recruited for a panel study from two abstinence-based treatment centers, a moderation drinking program, and untreated individuals from the local community. Quantitative measures of SR change between baseline and 6 months were used to predict 9-month drinking outcomes, controlling for baseline drinking and AA involvement. Results: Significant 6-month changes in 8 of 12 SR measures were found, which included private SR practices, beliefs, daily spiritual experiences, three measures of forgiveness, negative religious coping, and purpose in life. Increases in private SR practices and forgiveness of self were the strongest predictors of improvements in drinking outcomes. Changes in daily spiritual experiences, purpose in life, a general measure of forgiveness, and negative religious coping also predicted favorable drinking outcomes. Conclusions: SR change predicted good drinking outcomes in alcoholics, even when controlling for AA involvement. SR variables, broadly defined, deserve attention in fostering change even among those who do not affiliate with AA or religious institutions. Last, future research should include SR variables, particularly various types of forgiveness, given the strong effects found for forgiveness of self. PMID:21683048

Multiple metasomatic events recorded in Kilbourne Hole peridotite xenoliths: the relative contribution of host basalt interaction vs. silicate metasomatic glass

NASA Astrophysics Data System (ADS)

Hammond, S. J.; Yoshikawa, M.; Harvey, J.; Burton, K. W.

2010-12-01

Stark differences between bulk-rock lithophile trace element budgets and the sum of the contributions from their constituent minerals are common, if not ubiquitous in peridotite xenoliths [1]. In the absence of modal metasomatism this discrepancy is often attributed to the “catch-all”, yet often vague process of cryptic metasomatism. This study presents comprehensive Sr-Nd isotope ratios for variably metasomatized bulk-rock peridotites, host basalts, constituent peridotite mineral phases and interstitial glass from 13 spinel lherzolite and harzburgite xenoliths from the Kilbourne Hole volcanic maar, New Mexico, USA. Similar measurements were also made on hand-picked interstitial glass from one of the most highly metasomatized samples (KH03-16) in an attempt to unravel the effects of multiple metasomatic events. In all Kilbourne Hole peridotites analysed, hand-picked, optically clean clinopyroxenes preserve a more primitive Sr isotope signature than the corresponding bulk-rock; a pattern preserved in all but one sample for Nd isotope measurements. Reaction textures, avoided during hand-picking, around clinopyroxene grains are evident in the most metasomatized samples and accompanied by films of high-SiO2 interstitial glass. The margins of primary minerals appear partially resorbed and trails of glassy melt inclusions similar in appearance to those previously reported from the same locality [2], terminate in these films. Hand-picked glass from KH03-16 reveals the most enriched 87Sr/86Sr of any component recovered from these xenoliths (87Sr/86Sr = 0.708043 ± 0.00009; [Sr] = 81 ppm). Similarly, the 143Nd/144Nd of the glass is amongst the most enriched of the peridotite components (143Nd/144Nd = 0.512893 ± 0.000012; [Nd] = 10 ppm). However, the host basalt (87Sr/86Sr = 0.703953 ± 0.00012; 143Nd/144Nd = 0.512873 ± 0.000013), similar in composition to nearby contemporaneous Potrillo Volcanic Field basalts [3], contains nearly an order of magnitude more Sr and more than three times more Nd ([Sr] = 655 ppm; [Nd] = 34 ppm) than the interstitial glass. While the enriched nature of the host basalt, combined with high [Sr] and [Nd], makes it the most likely candidate for the enrichment of the peridotite bulk rocks, mixing between clinopyroxenes and the host basalt cannot account for the full range of bulk-rock Sr-Nd isotope ratios and nearly half of the xenoliths require an additional component that could involve varying amounts of interstitial glass. Moreover, three bulk-rock samples require a further, as yet unidentified component in order to explain the bulk-rock Sr-Nd isotope composition fully, implying that at least three episodes of metasomatism/refertilization must have occurred prior to the arrival of the xenoliths at the surface in their host lava. References: [1] Bedini & Bodinier (1999) Geochim. Cosmochim. Acta 63, 3883-3900. [2] Schiano & Clocchiatti (1994) Nature 368, 622-624. [3] Thompson et al., (2005) J. Petrol. 46, 1603-1643.

Oxygen Isotopes in Intra-Back Arc Basalts from the Andean Southern Volcanic Zone

NASA Astrophysics Data System (ADS)

Parks, B. H.; Wang, Z.; Saal, A. E.; Frey, F. A.; Blusztajn, J.

2013-12-01

The chemical compositions of volcanic rocks from the Andean Southern Volcanic Zone (SVZ) reflect complex and dynamic interactions among the subducting oceanic lithosphere, the mantle wedge, and the overlying continental crust. Oxygen isotope ratios of olivine phenocrysts can be a useful means to identifying their relative contributions to the arc magmatism. In this study, we report high-precision oxygen-isotope ratios of olivine phenocrysts in a set of intra-back arc basalts from the SVZ. The samples were collected from monogenetic cinder cones east of the volcanic front (35-39 degrees S), and have been geochemically well-characterized with major and trace element contents, and Sr-Nd-Pb isotope compositions. Compared to lavas from the volcanic front, these intra-back arc lavas have similar radiogenic isotope, and a more alkalic and primitive (higher MgO content) chemical composition. We determined the oxygen-isotope ratios using the CO2-laser-fluorination method set up at the Department of Geology and Geophysics, Yale University following the techniques reported in Wang et al (2011). The samples were analyzed with standards of Gore Mountain Garnet (5.77×0.12‰ 1σ; Valley et al., 1995) and Kilbourne Hole Olivine (5.23×0.07‰ 1σ; Sharp, 1990) in order to account for minor changes in the vacuum line during analyses. The obtained δ18OSMOW values of olivine phenocrysts from the intra-back arc basalts vary from 4.98×0.01 to 5.34×0.01‰. This range, surprisingly, is similar to the δ18O values of olivines from mantle peridotites (5.2×0.2‰). Preliminary results indicate significant correlations of 87Sr/86Sr, 143Nd/144Nd and trace element ratios of the basaltic matrix with the δ18O values of olivine phenocrysts, indicating at least three components involved in the formation of the arc volcanism. By comparing the δ18O with the variations of major and trace element contents (e.g., MgO, TiO2 and Ni), and trace element ratios (e.g. Ba/Nb), we evaluate the effects of fractionation crystallization, crustal contamination, the extent of slab flux, metasomatism, and melting of the mantle wedge on the intra-back arc lavas from the SVZ.

Chemistry of solutions from the 13°N East Pacific Rise hydrothermal site

NASA Astrophysics Data System (ADS)

Michard, G.; Albarède, F.; Michard, A.; Minster, J.-F.; Charlou, J.-L.; Tan, N.

1984-03-01

Ten samples were recovered by the submersible "Cyana" submersible from two groups of hydrothermal vents located 2600 m deep along the East Pacific Rise at 13°N. The maximum measured temperature was 317°C and minimum pH 3.8. A systematic determination of major and trace elements has been carried out and mixing lines between a high-temperature component (HTC) and seawater are observed. The water chemistry of the HTC slightly differs for several elements at the two sites. This HTC is deprived of SO 4 and Mg and is greatly enriched in most other species. Maximum concentrations are (in units per kg): Cl = 0.72mol; Br = 1.1mmol; Na = 0.55mol; K = 29mmol; Rb = 14 μmol; Ca = 52mmol; Sr = 170 μmol; Mn = 750 μmol; Fe = 1mmol; Al = 15 μmol; Si = 21mmol. For many elements, the magnitude of the anomaly relative to seawater does not compare with the results obtained from the Galapagos or East Pacific Rise 21°N. The enrichment of cations relative to seawater is likely related to the huge Cl excess through charge balance. The Br/Cl ratio is close to that for seawater. However, it is not clear whether the Cl excess is due to gas release or basalt hydration (formation of amphibole chlorite or epidote). P-T dependence of SiO 2 solubility suggests that water-rock interaction last occurred at a depth in excess of 1 km below the sea floor. A mixing line of 87Sr/ 86Sr vs. Mg/Sr demonstrates that the HTCs have a nearly identical 87Sr/ 86Sr ratio of 0.7041 for both sites. A water/rock ratio of about 5 is inferred, which differs from the 1.5 value obtained at 21°N.

Large-scale purification of 90Sr from nuclear waste materials for production of 90Y, a therapeutic medical radioisotope.

PubMed

Wester, Dennis W; Steele, Richard T; Rinehart, Donald E; DesChane, Jaquetta R; Carson, Katharine J; Rapko, Brian M; Tenforde, Thomas S

2003-07-01

A major limitation on the supply of the short-lived medical isotope 90Y (t1/2 = 64 h) is the available quantity of highly purified 90Sr generator material. A radiochemical production campaign was therefore undertaken to purify 1,500 Ci of 90Sr that had been isolated from fission waste materials. A series of alkaline precipitation steps removed all detectable traces of 137Cs, alpha emitters, and uranium and transuranic elements. Technical obstacles such as the buildup of gas pressure generated upon mixing large quantities of acid with solid 90Sr carbonate were overcome through safety features incorporated into the custom-built equipment used for 90Sr purification. Methods are described for analyzing the chemical and radiochemical purity of the final product and for accurately determining by gravimetry the quantities of 90Sr immobilized on stainless steel filters for future use.

Study of atomic and molecular emission spectra of Sr by laser induced breakdown spectroscopy (LIBS).

PubMed

Bhatt, Chet R; Alfarraj, Bader; Ayyalasomayajula, Krishna K; Ghany, Charles; Yueh, Fang Y; Singh, Jagdish P

2015-12-01

Laser Induced Breakdown Spectroscopy (LIBS) is an ideal analytical technique for in situ analysis of elemental composition. We have performed a comparative study of the quantitative and qualitative analysis of atomic and molecular emission from LIBS spectra. In our experiments, a mixture of SrCl2 and Al2O3 in powder form was used as a sample. The atomic emission from Sr and molecular emission from SrCl and SrO observed in LIBS spectra were analyzed. The optimum laser energies, gate delays, and gate widths for selected atomic lines and molecular bands were determined from spectra recorded at various experimental parameters. These optimum experimental conditions were used to collect calibration data, and the calibration curves were used to predict the Sr concentration. Limits of detection (LODs) for selected atomic and molecular emission spectra were determined.

Microwave properties of film Ba x Sr1 - x TiO3 ferroelectric variconds with a magnesium-containing additive

NASA Astrophysics Data System (ADS)

Tumarkin, A. V.; Tepina, E. R.; Nenasheva, E. A.; Kartenko, N. F.; Kozyrev, A. B.

2012-06-01

The electrophysical properties of bulk ceramics based on Ba x Sr1 - x TiO3 solid solutions with a Mg-containing additive and planar variconds based on ferroelectric films obtained by the ion-plasma sputtering of targets with different elemental compositions are studied. Controllability n( U) = C(0)/ C( U) and the dielectric loss tangent (tanδ) of ferroelectric variconds are measured as functions of the elemental composition of the ferroelectric. The figure of merit of the variconds is estimated, and the film composition providing the best electrophysical parameters is determined.

The laser microprobe mass analyser for determining partitioning of minor and trace elements among intimately associated macerals: an example from the Swallow Wood coal bed, Yorkshire, UK

USGS Publications Warehouse

Lyons, P.C.; Morelli, J.J.; Hercules, D.M.; Lineman, D.; Thompson-Rizer, C. L.; Dulong, F.T.

1990-01-01

A study of the elemental composition of intimately associated coal macerals in the English Swallow Wood coal bed was conducted using a laser microprobe mass analyser, and indicated a similar trace and minor elemental chemistry in the vitrinite and cutinite and a different elemental signature in the fusinite. Three to six sites were analysed within each maceral during the study by laser micro mass spectrometry (LAMMS). Al, Ba, Ca, Cl, Cr, Dy, F, Fe, Ga, K, Li, Mg, Na, S, Si, Sr, Ti, V, and Y were detected by LAMMS in all three macerals but not necessarily at each site analysed. The signal intensities of major isotopic peaks were normalized to the signal intensity of the m z 85 peak (C7H) to determine the relative minor- and trace-element concentrations among the three dominant macerals. The vitrinite and the cutinite were depleted in Ba, Ca, Dy, Li, Mg, Sr, and Y relative to their concentrations observed in the fusinite. The cutinite was distinguished over vitrinite by less Ti, V, Cr and Ca, and K Ca $ ??1 (relative signal intensities). The fusinite, relative to the cutinite and vitrinite, was relatively depleted in Cr, Sc, Ti, and V. The fusinite, as compared with both the cutinite and vitrinite, was relatively enriched in Ba, Ca, Dy, Li, Mg, Sr, and Y, and also showed the most intense m z 64, 65, 66 signals (possibly S2+, HS2+, H2S2+, respectively). The LAMMS data indicate a common source for most elements and selective loss from the maceral precursors in the peat or entrapment of certain elements as mineral matter, most likely during the peat stage or during early diagenesis. The relatively high amounts of Ba, Ca, Dy, Li, Mg, Sr, and Y in the fusinite are consistent with micron and submicron mineral-matter inclusions such as carbonates and Ca-Al phosphates (probably crandallite group minerals). Mineralogical data on the whole coal, the LAMMS chemistry of the vitrinite and cutinite, and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDAX) of the elements in the macerals are consistent with the presence of micron and submicron inclusions of clays such as kaolinite, illite, and Ca-rich or Ca-bearing minerals (e.g. calcite, Ca-Al phosphates, and illite) which are different in kind and proportions in the three macerals. The variance as measured by the F-statistic for all three macerals indicates generally a nonuniform distribution of minor and trace elements in all three macerals, thus supporting a mineral-matter (inorganic) origin of the elements analysed. Exceptions are Al, K, Fe, Ga, and Sr in the vitrinite and cutinite, which is consistent with organic complexing or a uniform distribution of micron or submicron mineral matter such as illite and phosphate(s). ?? 1990.

Anthrax and the geochemistry of soils in the contiguous United States

USGS Publications Warehouse

Griffin, Dale W.; Silvestri, Erin E.; Bowling, Charlena Y.; Boe, Timothy; Smith, David B.; Nichols, Tonya L.

2014-01-01

Soil geochemical data from sample sites in counties that reported occurrences of anthrax in wildlife and livestock since 2000 were evaluated against counties within the same states (MN, MT, ND, NV, OR, SD and TX) that did not report occurrences. These data identified the elements, calcium (Ca), manganese (Mn), phosphorus (P) and strontium (Sr), as having statistically significant differences in concentrations between county type (anthrax occurrence versus no occurrence). Tentative threshold values of the lowest concentrations of each of these elements (Ca = 0.43 wt %, Mn = 142 mg/kg, P = 180 mg/kg and Sr = 51 mg/kg) and average concentrations (Ca = 1.3 wt %, Mn = 463 mg/kg, P = 580 mg/kg and Sr = 170 mg/kg) were identified from anthrax-positive counties as prospective investigative tools in determining whether an outbreak had “potential” or was “likely” at any given geographic location in the contiguous United States.

The distribution of Sr and REE between diopside and silicate liquid. [Rare Earth Elements

NASA Technical Reports Server (NTRS)

Grutzeck, M.; Kridelbaugh, S.; Weill, D.

1974-01-01

Experimental determination of the distribution coefficients in diopside-liquid pairs for strontium and nine rare-earth elements in the system CaMgSi2O6-NaAlSi3O8-CaAl2Si2O8. In experiments in air at 1265 C it is found that most of the Sr(2+), Eu(2+), and RE(3+) ions substitute for Ca(2+) and, in addition, a coupled substitution of Al(3+) for Si(4+) occurs. All of the trace ions considered are found to be excluded from the diopside lattice relative to the liquid. In the case of the trivalent ions the exclusion is much more pronounced for La and Ce, which have ionic radii larger than that of Ca(2+) in 8-fold oxygen coordination. Divalent Sr and Eu with even larger radii are also strongly excluded.

Species arboreal as a bioindicator of the environmental pollution: Analysis by SR-TXRF

NASA Astrophysics Data System (ADS)

de Vives, Ana Elisa Sirito; Moreira, Silvana; Brienza, Sandra Maria Boscolo; Medeiros, Jean Gabriel S.; Filho, Mario Tomazello; Zucchi, Orghêda Luiza Araújo Domingues; do Nascimento Filho, Virgilio Franco; Barroso, Regina Cely

2007-08-01

This paper aims to study the environmental pollution in the tree development, in order to evaluate its use as bioindicator in urban and countrysides. The sample collection was carried out in Piracicaba city, São Paulo State, that presents high level of environmental contamination in water, soil and air, due to industrial activities, vehicle combustion, sugar-cane leaves burning in the harvesting, etc. The species Caesalpinia peltophoroides ("Sibipiruna") was selected because it is often used in urban arborization. Synchrotron radiation X-ray fluorescence technique (SR-TXRF) was employed to identify and quantify the elements and metals of nutritional and toxicological importance in the wood samples. The analysis was performed in the Brazilian Synchrotron Light Source Laboratory, using a white beam for excitation and an Si(Li) detector for X-ray detection. In several samples were quantified P, K, Ca, Ti, Fe, Sr, Ba and Pb elements.

The excretion of biotrace elements using the multitracer technique in tumour-bearing mice.

PubMed

Wang, X; Tian, J; Yin, X M; Zhang, X; Wang, Q Z

2000-12-01

A radioactive multitracer solution obtained from the nuclear reaction of selenium with 25 MeV/nucleon 40Ar ions was used for investigation of trace element excretion into the faeces and urine of cancerous mice. The excretion rates of 22 elements (Na, K, Rb, Mg, Ca, Sr, Ga, As, Sc, V, Cr, Mn, Co, Fe, Y, Zr, Mo, Nb, Tc, Ru, Ag and In) were simultaneously measured under strictly identical experimental conditions, in order to clarify the excretion behavior of these elements in cancerous mice. The faecal and urinary excretion rates of Mg, Sr, Ga, As, Sc, V, Cr, Mn, Co, Fe, Y, Zr, Nb, Ru and Mo in cancerous mice, showed the in highest value at 0-8 hours. The accumulative excretion of Ca, Mo, Y and Zr was decreased and Na, Fe, Mn and Co increased in tumour-bearing mice, when compared to normal mice.

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

Eaton, Craig; Brahlek, Matthew; Engel-Herbert, Roman, E-mail: rue2@psu.edu

The authors report the growth of stoichiometric SrVO{sub 3} thin films on (LaAlO{sub 3}){sub 0.3}(Sr{sub 2}AlTaO{sub 6}){sub 0.7} (001) substrates using hybrid molecular beam epitaxy. This growth approach employs a conventional effusion cell to supply elemental A-site Sr and the metalorganic precursor vanadium oxytriisopropoxide (VTIP) to supply vanadium. Oxygen is supplied in its molecular form through a gas inlet. An optimal VTIP:Sr flux ratio has been identified using reflection high-energy electron-diffraction, x-ray diffraction, atomic force microscopy, and scanning transmission electron microscopy, demonstrating stoichiometric SrVO{sub 3} films with atomically flat surface morphology. Away from the optimal VTIP:Sr flux, characteristic changes inmore » the crystalline structure and surface morphology of the films were found, enabling identification of the type of nonstoichiometry. For optimal VTIP:Sr flux ratios, high quality SrVO{sub 3} thin films were obtained with smallest deviation of the lattice parameter from the ideal value and with atomically smooth surfaces, indicative of the good cation stoichiometry achieved by this growth technique.« less

A Coast Mountains provenance for the Valdez and Orca groups, southern Alaska, based on Nd, Sr, and Pb isotopic evidence

USGS Publications Warehouse

Farmer, G.L.; Ayuso, R.; Plafker, G.

1993-01-01

Nd, Sr, and Pb isotopic data were obtained for fourteen fine- to coarse-grained samples of accreted flysch of the Late Cretaceous and early Tertiary Valdez and Orca Groups in southern Alaska to determine the flysch provenance. Argillites and greywackes from the Orca Group, as well as compositionally similar but higher metamorphic grade rocks from the Valdez Group, show a restricted range of correlated ??{lunate}Nd ( -0.6 to -3.8) and 87Sr 86Sr (0.7060-0.7080) at the time of sediment deposition ( ??? 50 Ma). Pb isotopic compositions also vary over a narrow range ( 206Pb 204Pb = 19.138-19.395, 207Pb 204Pb = 15.593-15.703, 208Pb 204Pb = 38.677-39.209), and in the Orca Group the samples generally become more radiogenic with decreasing ??{lunate}Nd and increasing 87Sr 86Sr. All samples have similar trace element compositions characterized by moderate light rare earth element enrichments, and low ratios of high field strength elements to large ion lithophile elements. Based on petrographic, geochemical, and isotopic data the sedimentary rocks are interpreted to have been derived largely from a Phanerozoic continental margin arc complex characterized by igneous rocks with ??{lunate}Nd values between 0 and -5. The latter conclusion is supported by the ??{lunate}Nd values of a tonalite clast and a rhyodacite clast in the Orca Group (??{lunate}Nd = -4.9 and -0.9, respectively). However, trondjemitic clasts in the Orca Group have significantly lower ??{lunate}Nd ( ??? -10) and require a derivation of a portion of the flysch from Precambrian crustal sources. The Nd, Sr, and Pb isotopic compositions of both the Valdez and Orca Groups overlap the values determined for intrusive igneous rocks exposed within the northern portion of the Late Cretaceous to early Tertiary Coast Mountains Plutonic Complex in western British Columbia and equivalent rocks in southeastern Alaska. The isotopic data support previous conclusions based on geologic studies which suggest that the flysch was shed from this portion of the batholith, and from overlying continental margin arc-related volcanic rocks, following its rapid uplift in the Late Cretaceous and early Tertiary. The Precambrian crustal material present in the flysch may have been derived from Late Proterozoic or older metasedimentary and metaigneous rocks now exposed along the western margin of the Coast Mountains Plutonic Complex. ?? 1993.

Crystal-chemical controls on the partitioning of Sr and Ba between plagioclase feldspar, silicate melts, and hydrothermal solutions

NASA Astrophysics Data System (ADS)

Blundy, Jonathan D.; Wood, Bernard J.

1991-01-01

The isothermal (750°C) experiments of LAGACHE and DUJON (1987) reveal that the partitioning of Sr between plagioclase feldspar and hydrothermal solutions is a funtion of the anorthite (An) content of the plagioclase, indicating that crystal chemistry may exert a powerful influence on trace element partitioning. In order to compare these results with those on trace element partitioning between plagioclase and silicate melts we have compiled from the literature a large dataset of experimental and volcanic distribution coefficients ( D's) for Sr (and Ba). These data, which span a compositional range from lunar basalt to high silica rhyolite and a temperature range of over 650°C, show a relationship between DSr (and DBa) and mole fraction An ( XAn) which is similar to that exhibited by the hydrothermal results obtained at constant temperature. Plots of In DSr and In DBa versus XAn are linear with negative slope, indicating that both elements are more compatible in albite than anorthite. In terms of molar distribution coefficients ( D Sr∗) the hydrothermal and silicate melt data display an identical linear relationship between RT In D Sr∗ (where T is the absolute temperature in K and R is the gas constant, 8.314 JK -1 mol -1) and XAn. We conclude therefore that crystal chemistry provides the dominant control on partitioning of Sr and Ba into plagioclase and that the effects of temperature, pressure, and fluid composition are minor. Apparent relationships between DSr (and DBa) and the reciprocal temperature (1/ T) are artefacts of the linear relationships between XAn and 1/ T in the experimental studies. By defining a Henry's law standard state for the silicate melts and hydrothermal solutions, and considering plagioclases to be ternary regular solutions, we are able to relate the observed relationships between RT In D i∗ (where i is Ba or Sr) and XAn to the excess free energies of the trace element partitioning reactions between plagioclase and melt or hydrothermal solution. The interaction parameters are consistent with simple models in which the larger Ba or Sr cations are accommodated by lattice strain in the host plagioclase lattice, which is assumed to be perfectly elastic and isotropic. Thus D i∗ is a function of the Young's modulus of the host crystal and the size mismatch between trace and host cations. The greater elasticity of albite relative to anorthite accounts for the observed preference of Sr and Ba for sodic plagioclases over calcic plagioclases. For geochemical purposes the weight fraction partition coefficient Di is of more value than its molar counterpart. Regression of the Di data versus XAn yields the semi-empirical relationships RTIn DSr = 26,800 - 26,700 · XAnRTIn DBa = 10,200 - 38,200 · XAn. Thus measurement of the An and trace element (Ba, Sr) contents of a magmatic plagioclase enables calculation of the Ba and Sr contents of the coexisting liquid, which can be extremely important in the deciphering of igneous processes. By reference to plagioclase fractionation in the simple An-Ab binary we show that failure to take into account the compositional dependence of DSr can result in erroneous interpretations of geochemical trends. We also consider applications to three natural igneous suites: the Aden Volcanics; the layered Kiglapait Intrusion, Labrador; and the southern Actamello Massif, Italy.

Using 87Sr/86Sr ratios to investigate changes in stream chemistry during snowmelt in the Provo River, Utah, USA

NASA Astrophysics Data System (ADS)

Hale, C. A.; Carling, G. T.; Fernandez, D. P.; Nelson, S.; Aanderud, Z.; Tingey, D. G.; Dastrup, D.

2017-12-01

Water chemistry in mountain streams is variable during spring snowmelt as shallow groundwater flow paths are activated in the watershed, introducing solutes derived from soil water. Sr isotopes and other tracers can be used to differentiate waters that have interacted with soils and dust (shallow groundwater) and bedrock (deep groundwater). To investigate processes controlling water chemistry during snowmelt, we analyzed 87Sr/86Sr ratios, Sr and other trace element concentrations in bulk snowpack, dust, soil, soil water, ephemeral channels, and river water during snowmelt runoff in the upper Provo River watershed in northern Utah, USA, over four years (2014-2017). Strontium concentrations in the river averaged 20 ppb during base flow and decreased to 10 ppb during snowmelt runoff. 87Sr/86Sr ratios were around 0.717 during base flow and decreased to 0.715 in 2014 and 0.713 in 2015 and 2016 during snowmelt, trending towards less radiogenic values of mineral dust inputs in the Uinta Mountain soils. Ephemeral channels, representing shallow flow paths with soil water inputs, had Sr concentrations between 7-20 ppb and 87Sr/86Sr ratios between 0.713-0.716. Snowpack Sr concentrations were generally <2 ppb with 87Sr/86Sr ratios between 0.710-711, similar to atmospheric dust inputs. The less radiogenic 87Sr/86Sr ratios and lower Sr concentrations in the river during snowmelt are likely a result of activating shallow groundwater flow paths, which allows melt water to interact with shallow soils that contain accumulated dust deposits with a less radiogenic 87Sr/86Sr ratio. These results suggest that flow paths and atmospheric dust are important to consider when investigating variable solute loads in mountain streams.

Allometric constraints on Sr/Ca and Ba/Ca partitioning in terrestrial mammalian trophic chains.

PubMed

Balter, Vincent

2004-03-01

In biological systems, strontium (Sr) and barium (Ba) are two non-essential elements, in comparison to calcium (Ca) which is essential. The Sr/Ca and Ba/Ca ratios tend to decrease in biochemical pathways which include Ca as an essential element, and these processes are termed biopurification of Ca. The quantitative pathway of the biopurification of Ca in relation to Sr and Ba between two biological reservoirs ( Rn and R(n -1)) is measured with an observed ratio (OR) expressed by the (Sr/Ca) Rn /(Sr/Ca)( Rn-1) and (Ba/Ca) Rn /(Ba/Ca)( Rn-1) ratios. For a mammalian organism, during the whole biopurification of Ca starting with the diet to the ultimate reservoir of Ca which is the bone, the mean values for ORSr and ORBa are 0.25 and 0.2, respectively. In this study, published Sr/Ca and Ba/Ca ratios are used for three sets of soils, plants, and bones of herbivorous and carnivorous mammals, each comprising a trophic chain, to illustrate the biopurification of Ca at the level of trophic chains. Calculated ORSr and ORBa of herbivore bones in relation to plants and of bones of carnivores in relation to bones of herbivores give ORSr=0.30+/-0.08 and ORBa=0.16+/-0.08, thus suggesting that trophic chains reflect the Sr/Ca and Ba/Ca fluxes that are prevalent at the level of a mammalian organism. The slopes of the three regression equations of log(Sr/Ca) vs. log(Ba/Ca) are similar, indicating that the process of biopurification of Ca with respect to Sr and Ba is due to biological processes and is independent of the geological settings. Modifications of the logarithmic expression of the Sr/Ca and Ba/Ca relationship allow a new formula of the biopurification process to be deduced, leading to the general equation ORBa=ORSr(1.79+/-0.33), where the allometric coefficient is the mean of the slopes of the three regression equations. Some recent examples are used to illustrate this new analysis of predator-prey relations between mammals. This opens up new possibilities for the utilization of Ba/Ca and Sr/Ca in addition to stable isotope ratios (delta13C and delta15N) for the determination of the relative contribution of different food sources to an animal's diet.

Coal fly ash basins as an attractive nuisance to birds: parental provisioning exposes nestlings to harmful trace elements.

PubMed

Bryan, A L; Hopkins, W A; Parikh, J H; Jackson, B P; Unrine, J M

2012-02-01

Birds attracted to nest around coal ash settling basins may expose their young to contaminants by provisioning them with contaminated food. Diet and tissues of Common Grackle (Quiscalus quiscala) nestlings were analyzed for trace elements to determine if nestlings were accumulating elements via dietary exposure and if feather growth limits elemental accumulation in other tissues. Arsenic, cadmium, and selenium concentrations in ash basin diets were 5× higher than reference diets. Arsenic, cadmium, and selenium concentrations were elevated in feather, liver, and carcass, but only liver Se concentrations approached levels of concern. Approximately 15% of the total body burden of Se, As, and Cd was sequestered in feathers of older (>5 days) nestlings, whereas only 1% of the total body burden of Sr was sequestered in feathers. Feather concentrations of only three elements (As, Se, and Sr) were correlated with liver concentrations, indicating their value as non-lethal indicators of exposure. Copyright © 2011 Elsevier Ltd. All rights reserved.

Determination of trace elements in honey from different regions in Rio de Janeiro State (Brazil) by total reflection X-ray fluorescence.

PubMed

Ribeiro, Roberta de Oliveira Resende; Mársico, Eliane Teixeira; de Jesus, Edgar Francisco Oliveira; da Silva Carneiro, Carla; Júnior, Carlos Adam Conte; de Almeida, Eduardo; Filho, Virgílio Franco do Nascimento

2014-04-01

Trace and minor elements in Brazilian honey were analyzed by total reflection X-ray fluorescence spectroscopy. Up to 12 elements (K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, and Sr) were detected in 160 samples of honey from 4 regions of Rio de Janeiro State (Barra Mansa, Teresópolis, northern and southern Nova Friburgo). The results showed the samples from Teresópolis had higher rates of essential and nonessential elements than samples from the other regions, except for Ni. K and Ca were the most abundant elements in all samples, in the range of 116.5 to 987.0 μg g(-1) . Ni, Cu, Zn, Se, and Sr were identified in small concentrations (0.01 to 12.08 μg g(-1) ) in all samples, indicating a low level of contamination in all the regions. © 2014 Institute of Food Technologists®

The calcium-sensing receptor changes cell shape via a beta-arrestin-1 ARNO ARF6 ELMO protein network.

PubMed

Bouschet, Tristan; Martin, Stéphane; Kanamarlapudi, Venkateswarlu; Mundell, Stuart; Henley, Jeremy M

2007-08-01

G-protein-coupled receptors (GPCRs) transduce the binding of extracellular stimuli into intracellular signalling cascades that can lead to morphological changes. Here, we demonstrate that stimulation of the calcium-sensing receptor (CaSR), a GPCR that promotes chemotaxis by detecting increases in extracellular calcium, triggers plasma membrane (PM) ruffling via a pathway that involves beta-arrestin 1, Arf nucleotide binding site opener (ARNO), ADP-ribosylating factor 6 (ARF6) and engulfment and cell motility protein (ELMO). Expression of dominant negative beta-arrestin 1 or its knockdown with siRNA impaired the CaSR-induced PM ruffling response. Expression of a catalytically inactive ARNO also reduced CaSR-induced PM ruffling. Furthermore, beta-arrestin 1 co-immunoprecipitated with the CaSR and ARNO under resting conditions. Agonist treatment did not markedly alter beta-arrestin 1 binding to the CaSR or to ARNO but it did elicit the translocation and colocalisation of the CaSR, beta-arrestin 1 and ARNO to membrane protrusions. Furthermore, ARF6 and ELMO, two proteins known to couple ARNO to the cytoskeleton, were required for CaSR-dependent morphological changes and translocated to the PM ruffles. These data suggest that cells ruffle upon CaSR stimulation via a mechanism that involves translocation of beta-arrestin 1 pre-assembled with the CaSR or ARNO, and that ELMO plays an essential role in this CaSR-signalling-induced cytoskeletal reorganisation.

Thickness dependent thermoelectric properties of SrTiO3/SrLaTiO3 and SrZrO3/SrLaTiO3 heterostructures

NASA Astrophysics Data System (ADS)

Ishii, Masatoshi; Baniecki, John; Schafranek, Robert; Kerman, Kian; Kurihara, Kazuaki

2013-03-01

Thermoelectric power generators will be required for future sensor network systems. SrTiO3 (STO) is one candidate thermoelectric material due to its non-toxicity and comparable power factor to Bismuth telluride. The energy conversion efficiency of SrTiO3-based thermoelectric energy conversion elements has been reported to be enhanced by quantum size effects, such as the two dimensional (2D) electron gas in SrTiO3/SrTi0.8Nb0.2O3/SrTiO3. Nevertheless, a complete understanding of the mechanisms for the reported increase in efficiency are missing owing to a lack of understanding of the thickness dependence of the transport properties. In the talk, we will present a study of the thickness dependence of the transport properties of SrTiO3/SrLaTiO3 and SrZrO3/SrLaTiO3 heterostructures. The SrZrO3/SrLaTiO3 interface has a large conduction band off-set of 1.9 eV which can be utilized to confine electrons in a 2D quantum well. Characterization of the thermopower, conductivity, and Hall effect will be presented as a function of the SrLaTiO3 thickness down to a few unit cells and the implications of the thickness dependence of the transport properties on carrier confinement and increasing the efficiency STO-based 2DEG quantum well structures will be discussed.

Measuring the content of 17 elements in the flesh of Prunus cerasifera and its cultivars by ICP-MS.

PubMed

Shen, Jing; Xue, Hai-Yan; Li, Gai-Ru; Lu, Yi; Yao, Jun

2014-09-01

The present study compared the contents of inorganic elements in the pulp of purple, red, and yellow Prunus cerasifera with its cultivars. A method was established for the analysis of 17 kinds of trace elements (K, Ca, Mg, Na, Fe, Mn, Cu, Zn, Be, Li, Se, Sr, Cr, Pb, Cd, As and Hg) in the flesh of Prunus cerasifera by microwave digestion-ICP-MS. The detection method is simple and quick, yet shoes high precision and high sensitivity. The recovery rate of 17 elements ranged, from 93.5% to 110.4%. The analysis results showed that the contents of 17 elements in the flesh of purple, red, and yellow Prunus cerasifera and its cultivars are similar, containing extremely rich K elements (as high as 1 per thousand) and higher contents of Ca, Mg, Na, Fe and Mn. The contents of Cu, Zn, Li, Se, Sr and Cr are also present. The contents of Pb, Cd, As, Hg and other harmful element are either very low or not detectable. The experimental results for the study of trace elements in pulp of Prunus cerasifera and its cultivars provide empirical data for. future research in this area.

Forage grasses with lower uptake of caesium and strontium could provide ‘safer’ crops for radiologically contaminated areas

PubMed Central

Beresford, Nicholas A.; Crout, Neil M. J.; Lovatt, J. Alan; Thomson, Russell; Broadley, Martin R.

2017-01-01

Substitution of a species or cultivar with higher uptake of an element by one with lower uptake has been proposed as a remediation strategy following accidental releases of radioactivity. However, despite the importance of pasture systems for radiological dose, species/cultivar substitution has not been thoroughly investigated for forage grasses. 397 cultivars from four forage grass species; hybrid ryegrass (Lolium perenne L. x Lolium multiflorum Lam.), perennial ryegrass (Lolium perenne L.), Italian ryegrass (Lolium multiflorum Lam.) and tall fescue (Festuca arundinacea Shreb.); were sampled from 19 field-based breeding experiments in Aberystwyth and Edinburgh (UK) in spring 2013 and analysed for caesium (Cs) and strontium (Sr) concentrations. In order to calculate concentration ratios (CRs; the concentration of an element in a plant in relation to the concentration in the soil), soils from the experiments were also analysed to calculate extractable concentrations of Cs and Sr. To test if cultivars have consistently low Cs and Sr concentration ratios, 17 hybrid ryegrass cultivars were sampled from both sites again in summer 2013 and spring and summer 2014. Tall fescue cultivars had lower Cs and Sr CRs than the other species. Three of the selected 17 hybrid ryegrass cultivars had consistently low Cs CRs, two had consistently low Sr CRs and one had consistently low Cs and Sr CRs. Cultivar substitution could reduce Cs CRs by up to 14-fold and Sr CRs by 4-fold in hybrid ryegrass. The identification of species and cultivars with consistently low CRs suggests that species or cultivar substitution could be an effective remediation strategy for contaminated areas. PMID:28459808

Strontium isotope ratios (87Sr/86Sr) of tooth enamel: a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods.

PubMed

Copeland, Sandi R; Sponheimer, Matt; le Roux, Petrus J; Grimes, Vaughan; Lee-Thorp, Julia A; de Ruiter, Darryl J; Richards, Michael P

2008-10-01

Strontium isotope ratios (87Sr/86Sr) in tooth enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring (87)Sr/(86)Sr in teeth use bulk sampling (5-20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring tooth enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 +/- 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-tooth samples and small and/or rare specimens such as micromammal and fossil teeth.

Multifunctional Oxide Films for Advanced Multifunction RF Systems

DTIC Science & Technology

2007-09-14

during the epitaxy runs. Effusion cells (SVT) provide perovskite and rocksalt matrix elements (Ti, Ba , Sr , Mg). An e-gun evaporator (MDC):can be used to...sample that best matched the targeted stoichiometry. 10 5 MgO Ba 0 . Sr 1.4 TiO3/MgO 10 000 BS I 102 3~) ;101 0~ 0 (a) RHiEED of BST rowthonM 0 105O... Ba 0. Sr .. iO3 /SrMO. 5 200 1Is V STO10 -STO 3 -10 _ 10 2 30S 15 10 100 10 20 30 40 50 60 70 80 90 20 (b) RHEED of BST growth on STO (c) XRD scan of

Alkali trace elements in Gale crater, Mars, with ChemCam: Calibration update and geological implications

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

Payre, Valerie; Fabre, Cecile; Cousin, Agnes

The Chemistry Camera (ChemCam) instrument onboard Curiosity can detect minor and trace elements such as lithium, strontium, rubidium, and barium. Their abundances can provide some insights about Mars' magmatic history and sedimentary processes. We focus on developing new quantitative models for these elements by using a new laboratory database (more than 400 samples) that displays diverse compositions that are more relevant for Gale crater than the previous ChemCam database. These models are based on univariate calibration curves. For each element, the best model is selected depending on the results obtained by using the ChemCam calibration targets onboard Curiosity. New quantificationsmore » of Li, Sr, Rb, and Ba in Gale samples have been obtained for the first 1000 Martian days. Comparing these data in alkaline and magnesian rocks with the felsic and mafic clasts from the Martian meteorite NWA7533—from approximately the same geologic period—we observe a similar behavior: Sr, Rb, and Ba are more concentrated in soluble- and incompatible-element-rich mineral phases (Si, Al, and alkali-rich). Correlations between these trace elements and potassium in materials analyzed by ChemCam reveal a strong affinity with K-bearing phases such as feldspars, K-phyllosilicates, and potentially micas in igneous and sedimentary rocks. However, lithium is found in comparable abundances in alkali-rich and magnesium-rich Gale rocks. This very soluble element can be associated with both alkali and Mg-Fe phases such as pyroxene and feldspar. Here, these observations of Li, Sr, Rb, and Ba mineralogical associations highlight their substitution with potassium and their incompatibility in magmatic melts.« less

Alkali trace elements in Gale crater, Mars, with ChemCam: Calibration update and geological implications

DOE PAGES

Payre, Valerie; Fabre, Cecile; Cousin, Agnes; ...

2017-03-20

The Chemistry Camera (ChemCam) instrument onboard Curiosity can detect minor and trace elements such as lithium, strontium, rubidium, and barium. Their abundances can provide some insights about Mars' magmatic history and sedimentary processes. We focus on developing new quantitative models for these elements by using a new laboratory database (more than 400 samples) that displays diverse compositions that are more relevant for Gale crater than the previous ChemCam database. These models are based on univariate calibration curves. For each element, the best model is selected depending on the results obtained by using the ChemCam calibration targets onboard Curiosity. New quantificationsmore » of Li, Sr, Rb, and Ba in Gale samples have been obtained for the first 1000 Martian days. Comparing these data in alkaline and magnesian rocks with the felsic and mafic clasts from the Martian meteorite NWA7533—from approximately the same geologic period—we observe a similar behavior: Sr, Rb, and Ba are more concentrated in soluble- and incompatible-element-rich mineral phases (Si, Al, and alkali-rich). Correlations between these trace elements and potassium in materials analyzed by ChemCam reveal a strong affinity with K-bearing phases such as feldspars, K-phyllosilicates, and potentially micas in igneous and sedimentary rocks. However, lithium is found in comparable abundances in alkali-rich and magnesium-rich Gale rocks. This very soluble element can be associated with both alkali and Mg-Fe phases such as pyroxene and feldspar. Here, these observations of Li, Sr, Rb, and Ba mineralogical associations highlight their substitution with potassium and their incompatibility in magmatic melts.« less

Determination of stoichiometry and concentration of trace elements in thin BaxSr1-xTiO3 perovskite layers.

PubMed

Becker, J S; Boulyga, S F

2001-07-01

This paper describes an analytical procedure for determining the stoichiometry of BaxSr1-xTiO3 perovskite layers using inductively coupled plasma mass spectrometry (ICP-MS). The analytical results of mass spectrometry measurements are compared to those of X-ray fluorescence analysis (XRF). The performance and the limits of solid-state mass spectrometry analytical methods for the surface analysis of thin BaxSr1-xTiO3 perovskite layers sputtered neutral mass spectrometry (SNMS)--are investigated and discussed.

Some methodical peculiarities of analysis of small-mass samples by SRXFA

NASA Astrophysics Data System (ADS)

Kudryashova, A. F.; Tarasov, L. S.; Ulyanov, A. A.; Baryshev, V. B.

1989-10-01

The stability of work of the element analysis station on the storage rings VEPP-3 and VEPP-4 in INP (Novosibirsk, USSR) was demonstrated on the example of three sets of rare element analyses carried out by SRXFA in May 1985, January and May-June 1988. These data show that there are some systematic deviations in the results of measurements of Zr and La contents. SRXFA and INAA data have been compared for the latter element. A false linear correlation on the Rb-Sr plot in one set of analyses has been attributed to an overlapping artificial Sr peak on a Rb peak. The authors proposed sequences of registration of spectra and computer treatment for samples and standards. Such sequences result in better final concentration data.

Trace element geochemistry (Li, Ba, Sr, and Rb) using Curiosity's ChemCam: early results for Gale crater from Bradbury Landing Site to Rocknest

USGS Publications Warehouse

Ollila, Ann M.; Newsom, Horton E.; Clark, Benton; Wiens, Roger C.; Cousin, Agnes; Blank, Jen G.; Mangold, Nicolas; Sautter, Violaine; Maurice, Sylvestre; Clegg, Samuel M.; Gasnault, Olivier; Forni, Olivier; Tokar, Robert; Lewin, Eric; Dyar, M. Darby; Lasue, Jeremie; Anderson, Ryan; McLennan, Scott M.; Bridges, John; Vaniman, Dave; Lanza, Nina; Fabre, Cecile; Melikechi, Noureddine; Perett, Glynis M.; Campbell, John L.; King, Penelope L.; Barraclough, Bruce; Delapp, Dorothea; Johnstone, Stephen; Meslin, Pierre-Yves; Rosen-Gooding, Anya; Williams, Josh

2014-01-01

The ChemCam instrument package on the Mars rover, Curiosity, provides new capabilities to probe the abundances of certain trace elements in the rocks and soils on Mars using the laser-induced breakdown spectroscopy technique. We focus on detecting and quantifying Li, Ba, Rb, and Sr in targets analyzed during the first 100 sols, from Bradbury Landing Site to Rocknest. Univariate peak area models and multivariate partial least squares models are presented. Li, detected for the first time directly on Mars, is generally low (100 ppm and >1000 ppm, respectively. These analysis locations tend to have high Si and alkali abundances, consistent with a feldspar composition. Together, these trace element observations provide possible evidence of magma differentiation and aqueous alteration.

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.

Petrogenesis of Early Cretaceous dioritic dikes in the Shanyang-Zhashui area, South Qinling, central China: Evidence for partial melting of thickened lower continental crust

NASA Astrophysics Data System (ADS)

Chen, Lei; Yan, Zhen; Wang, Zongqi; Wang, Kunming

2018-06-01

The dioritic dikes distributed in the Shanyang-Zhashui area of the South Qinling region play an important role in understanding the deep magmatic processes and tectonic evolution during the orogenic process. The zircon Usbnd Pb ages of the dioritic dikes indicate that they were emplaced at ∼144 Ma and therefore postdate the dikes that formed in the intracontinental orogenic background after the continental collision between the North China Block (NCB) and the South China Block (SCB). The dioritic dikes have SiO2 contents of 56.86-64.93 wt%; K2O contents of 1.65-3.21 wt%; low MgO (1.50-2.66 wt%), Y (14.4-25.5 ppm) and heavy rare earth element (HREE) contents; low Mg# values (39.9-49); high Sr contents (528-4833 ppm); and high Sr/Y ratios (32.8-189). They exhibit highly fractionated REE and flat HREE patterns, strong enrichment in large ion lithophile elements (LILEs; e.g., Rb, Ba, and U) and depletion in high field strength elements (HFSEs) (e.g., Nb), as well as positive Sr and negative Ti anomalies. Furthermore, these dioritic dikes exhibit (87Sr/86Sr)i ratios ranging from 0.7048 to 0.7083, εNd(t) values ranging from -3.3 to -1.4, and εHf(t) values ranging from -4.1 to 1.6. The geochemical patterns of the dioritic dikes indicate that they possess adakitic characteristics. Moreover, the low MgO contents, Mg# values, Ni contents, Th/Ce ratios, and Srsbnd Ndsbnd Hf isotopic features all indicate that these dioritic dikes were generated by the partial melting of thickened mafic lower crust. The high La/Yb and Sr/Y ratios, low Y and Yb contents, absence of significant Eu anomalies, flat HREE patterns, and low Nb/Ta ratios of these rocks suggest that the adakitic melts were derived from the melting of garnet-bearing amphibolite. The geochronologic, elemental and isotopic evidence suggests that the dioritic dikes may have formed in a locally extensional environment within an overall N-S compressional setting or during the transition from compressional to extensional environments in the Early Cretaceous. This process resulted in the upwelling of the asthenospheric or lithospheric mantle, causing partial melting of the mafic lower crust and forming the adakitic dioritic melts.

Behaviour of elements in soils developed from nephelinites at Mount Etinde (Cameroon): Impact of hydrothermal versus weathering processes

NASA Astrophysics Data System (ADS)

Etame, J.; Gerard, M.; Bilong, P.; Suh, C. E.

2009-05-01

The progressive weathering of 0.65 Ma nephelinites from Mount Etinde (South Western Cameroon) in a humid tropical setting has resulted in the formation of a 150 cm thick weathering crust. The soil profiles consist of three horizons: Ah/Bw/C. A major differentiation of the chemical and mineralogical parameters is related to the complexity of the saprolites, some of which were hydrothermally altered. Bulk geochemical and microgeochemical analyses were performed on selected minerals from the different horizons of two reference profiles, of which one (E 4) was developed from unaltered nephelinite (nephelinite U) while the other (BO 1) formed from hydrothermally altered nephelinite (nephelinite H). The results show that the primary minerals (clinopyroxene, nepheline, leucite, haüyne, titanomagnetite, perovskite, apatite and sphene) experienced differential weathering rates with primary minerals rich in rare earth elements (titanomagnetite, perovskite, apatite and sphene) surviving in the saprolite and the Bw horizons. The weathering of the primary minerals is reflected in the leaching of alkaline and alkaline-earth elements, except for Ba and Rb in the hydrothermalised nephelinite soil. The order of mobility is influenced by hydrothermal processes: Na > K > Rb > Ca > Cs > Sr in nephelinite U soil , Na > K > Sr > Ca > Mg in nephelinite H soil; Rb/Sr and Sr/Mg can be used as indicators of the kinetic of the weathering on nephelinite U and on nephelinite H. Barium enrichment is related to variable concentrations in the nephelinites, to the formation of crandallites and the leaching of surface horizons. The content of metallic elements is higher in nephelinite H soil than in the nephelinite U soil. Results show that hydrothermal alteration leads to an enrichment of light (La, Ce, Nd) and intermediate (Sm, Eu, Dy) rare earth elements. The enrichment in Cr and Pb in the surface horizons is discussed in relation to organic matter activity, the dissolution of magnetites, and the impact of hydrothermal processes as well as atmospheric pollution in the case of lead.

Incorporation of Trace Elements in Ancient and Modern Human Bone: An X-Ray Absorption Spectroscopy Study

NASA Astrophysics Data System (ADS)

Pingitore, N. E.; Cruz-Jimenez, G.; Price, T. D.

2001-12-01

X-ray absorption spectroscopy (XAS) affords the opportunity to probe the atomic environment of trace elements in human bone. We are using XAS to investigate the mode(s) of incorporation of Sr, Zn, Pb, and Ba in both modern and ancient (and thus possibly altered) human and animal bone. Because burial and diagenesis may add trace elements to bone, we performed XAS analysis on samples of pristine contemporary and ancient, buried human and animal bone. We assume that deposition of these elements during burial occurs by processes distinct from those in vivo, and this will be reflected in their atomic environments. Archaeologists measure strontium in human and animal bone as a guide to diet. Carnivores show lower Sr/Ca ratios than their herbivore prey due to discrimination against Sr relative to Ca up the food chain. In an initial sample suite no difference was observed between modern and buried bone. Analysis of additional buried samples, using a more sensitive detector, revealed significant differences in the distance to the second and third neighbors of the Sr in some of the buried samples. Distances to the first neighbor, oxygen, were similar in all samples. Zinc is also used in paleo-diet studies. Initial x-ray absorption spectroscopy of a limited suite of bones did not reveal any differences between modern and buried samples. This may reflect the limited number of samples examined or the low levels of Zn in typical aqueous solutions in soils. Signals from barium and lead were too low to record useful XAS spectra. Additional samples will be studied for Zn, Ba, and Pb. We conducted our XAS experiments on beam lines 4-1 and 4-3 at the Stanford Synchrotron Radiation Laboratory. Data were collected in the fluorescence mode, using a Lytle detector and appropriate filter, and a solid state, 13-element Ge-detector.

Detection of trace metallic elements in oral lichenoid contact lesions using SR-XRF, PIXE, and XAFS

PubMed Central

Sugiyama, Tomoko; Uo, Motohiro; Wada, Takahiro; Omagari, Daisuke; Komiyama, Kazuo; Miyazaki, Serika; Numako, Chiya; Noguchi, Tadahide; Jinbu, Yoshinori; Kusama, Mikio; Mori, Yoshiyuki

2015-01-01

Oral lichen planus (OLP) and oral lichenoid contact lesions (OLCL) are chronic inflammatory mucocutaneous reactions with a risk of malignant transformation that alter the epithelium. OLP and OLCL have similar clinical and histopathological features and it is difficult to distinguish one from the other. Metallic restorations are suspected to generate OLCLs. Trace metal analysis of OLCL specimens may facilitate the discrimination of symptoms and identification of causative metallic restorations. The purpose of this study was to assess OLCL tissue samples for the prevalence of metallic elements derived from dental restorations, and to discriminate OLCL from OLP by using synchrotron radiation-excited X-ray fluorescence analysis (SR-XRF), particle-induced X-ray emission (PIXE), and X-ray absorption fine structure (XAFS). Typical elements of dental materials were detected in the OLCL, whereas no obvious element accumulation was detected in OLP and negative control specimens. The origin of the detected metallic elements was presumed to be dental alloys through erosion. Therefore, our findings support the feasibility of providing supporting information to distinguish OLCL from OLP by using elemental analysis. PMID:26085368

The Calcium-Sensing Receptor Increases Activity of the Renal NCC through the WNK4-SPAK Pathway.

PubMed

Bazúa-Valenti, Silvana; Rojas-Vega, Lorena; Castañeda-Bueno, María; Barrera-Chimal, Jonatan; Bautista, Rocío; Cervantes-Pérez, Luz G; Vázquez, Norma; Plata, Consuelo; Murillo-de-Ozores, Adrián R; González-Mariscal, Lorenza; Ellison, David H; Riccardi, Daniela; Bobadilla, Norma A; Gamba, Gerardo

2018-05-30

Background Hypercalciuria can result from activation of the basolateral calcium-sensing receptor (CaSR), which in the thick ascending limb of Henle's loop controls Ca 2+ excretion and NaCl reabsorption in response to extracellular Ca 2+ However, the function of CaSR in the regulation of NaCl reabsorption in the distal convoluted tubule (DCT) is unknown. We hypothesized that CaSR in this location is involved in activating the thiazide-sensitive NaCl cotransporter (NCC) to prevent NaCl loss. Methods We used a combination of in vitro and in vivo models to examine the effects of CaSR on NCC activity. Because the KLHL3-WNK4-SPAK pathway is involved in regulating NaCl reabsorption in the DCT, we assessed the involvement of this pathway as well. Results Thiazide-sensitive 22 Na + uptake assays in Xenopus laevis oocytes revealed that NCC activity increased in a WNK4-dependent manner upon activation of CaSR with Gd 3+ In HEK293 cells, treatment with the calcimimetic R-568 stimulated SPAK phosphorylation only in the presence of WNK4. The WNK4 inhibitor WNK463 also prevented this effect. Furthermore, CaSR activation in HEK293 cells led to phosphorylation of KLHL3 and WNK4 and increased WNK4 abundance and activity. Finally, acute oral administration of R-568 in mice led to the phosphorylation of NCC. Conclusions Activation of CaSR can increase NCC activity via the WNK4-SPAK pathway. It is possible that activation of CaSR by Ca 2+ in the apical membrane of the DCT increases NaCl reabsorption by NCC, with the consequent, well known decrease of Ca 2+ reabsorption, further promoting hypercalciuria. Copyright © 2018 by the American Society of Nephrology.

Temporal and spectral profiles of stimulus-stimulus and stimulus-response conflict processing.

PubMed

Wang, Kai; Li, Qi; Zheng, Ya; Wang, Hongbin; Liu, Xun

2014-04-01

The ability to detect and resolve conflict is an essential function of cognitive control. Laboratory studies often use stimulus-response-compatibility (SRC) tasks to examine conflict processing in order to elucidate the mechanism and modular organization of cognitive control. Inspired by two influential theories regarding cognitive control, the conflict monitoring theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001) and dimensional overlap taxonomy (Kornblum, Hasbroucq, & Osman, 1990), we explored the temporal and spectral similarities and differences between processing of stimulus-stimulus (S-S) and stimulus-response (S-R) conflicts with event related potential (ERP) and time-frequency measures. We predicted that processing of S-S conflict starts earlier than that of S-R conflict and that the two types of conflict may involve different frequency bands. Participants were asked to perform two parallel SRC tasks, both combining the Stroop task (involving S-S conflict) and Simon task (involving S-R conflict). ERP results showed pronounced SRC effects (incongruent vs. congruent) on N2 and P3 components for both S-S and S-R conflicts. In both tasks, SRC effects of S-S conflict took place earlier than those of S-R conflict. Time-frequency analysis revealed that both types of SRC effects modulated theta and alpha bands, while S-R conflict effects additionally modulated power in the beta band. These results indicated that although S-S and S-R conflict processing shared considerable ERP and time-frequency properties, they differed in temporal and spectral dynamics. We suggest that the modular organization of cognitive control should take both commonality and distinction of S-S and S-R conflict processing into consideration. Copyright © 2013 Elsevier Inc. All rights reserved.

Fluid and element transfer at the slab-mantle interface: insights from the serpentinized Livingstone Fault, New Zealand

NASA Astrophysics Data System (ADS)

Smith, S. A. F.; Scott, J.; Tarling, M.; Tulley, C. J.; le Roux, P. J.

2017-12-01

At the slab-mantle interface in subduction zones, hydrous fluids released by dehydration reactions are fluxed upwards into the fore-arc mantle corner. The extent to which these fluids can move across the plate interface shear zone has significant implications for understanding the composition of the mantle wedge and the origin of episodic tremor and slow slip. The >1000 km long Livingstone Fault in New Zealand provides a superbly exposed analogue (both in terms of scale and the rock types involved) for the serpentinite shear zone likely to be present along the slab-mantle interface. The Livingstone Fault is a sheared serpentinite mélange up to several hundreds of meters wide that separates greenschist-facies quartzofeldspathic metasediments (e.g. analogue for slab sediments) from variably-serpentinized harzburgitic peridotite (e.g. analogue for mantle wedge). To track element mobility and paleo-fluid flow across the shear zone, Sr and Nd isotopes were measured in five transects across the metasediments, mélange and serpentinized peridotites. Results show that the mélange and serpentinized peridotites (originally with Sr and Nd similar to Permian MORB) were progressively overprinted with the isotopic composition of the metasediments at distances of up to c. 400 m from the mélange-metasediment contact. Mass balance calculations require that many elements were mobile across the mélange shear zone, but permeability modeling indicates that diffusive transfer of such elements is unrealistically slow. Instead, it appears that fluid and element percolation in to and across the mélange was aided by episodic over-pressuring and fracturing, as indicated by the widespread presence of tremolite-bearing breccias and veins that mutually cross-cut the serpentinite mélange fabrics. Overall, the field and isotopic results indicate that fluid and element redistribution within major serpentinite-bearing shear zones is strongly aided by fracturing and brecciation that are triggered by episodic fluid over-pressuring. By comparison to recent geophysical and experimental results, we infer that high fluid pressures and the resultant brittle failure processes may contribute to the slow slip and tremor signal near the forearc mantle corner.

Ionomic profiling of Nicotiana langsdorffii wild-type and mutant genotypes exposed to abiotic stresses.

PubMed

Ardini, Francisco; Soggia, Francesco; Abelmoschi, Maria Luisa; Magi, Emanuele; Grotti, Marco

2013-01-01

To provide a new insight into the response of plants to abiotic stresses, the ionomic profiles of Nicotiana langsdorffii specimens have been determined before and after exposure to toxic metals (chromium) or drought conditions. The plants were genetically transformed with the rat glucocorticoid receptor (GR) or the gene for Agrobacterium rhizogenes rolC, because these modifications are known to produce an imbalance in phytohormone equilibria and a significant change in the defence response of the plant. Elemental profiles were obtained by developing and applying analytical procedures based on inductively coupled plasma atomic emission and mass spectrometry (ICP-AES/MS). In particular, the removal of isobaric interferences affecting the determination of Cr and V by ICP-MS was accomplished by use of a dynamic reaction cell, after optimization of the relevant conditions. The combined use of ICP atomic emission and mass spectrometry enabled the determination of 29 major and trace elements (Ba, Bi, Ca, Cd, Co, Cr, Cu, Eu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, P, Pb, Pt, Rb, S, Sb, Sn, Sr, Te, V, W, Y, and Zn) in different parts of the plants (roots, stems, and leaves), with high accuracy and precision. Multivariate data processing and study of element distribution patterns provided new information about the ionomic response of the target organism to chemical treatment or water stress. Genetic modification mainly affected the distribution of Bi, Cr, Mo, Na, and S, indicating that these elements were involved in biochemical processes controlled by the GR or rolC genes. Chemical stress strongly affected accumulation of several elements (Ba, Ca, Fe, Ga, K, Li, Mn, Mo, Na, P, Pb, Rb, S, Sn, Te, V, and Zn) in different ways; for Ca, Fe, K, Mn, Na, and P the effect was quite similar to that observed in other studies after treatment with other transition elements, for example Cu and Cd. The effect of water deficit was less evident, mainly consisting in a decrease of Ba, Cr, Na, and Sr in roots.

Compositional heterogeneity of the Sugarloaf melilite nephelinite flow, Honolulu Volcanics, Hawai'i

NASA Astrophysics Data System (ADS)

Clague, David A.; Frey, Frederick A.; Garcia, Michael O.; Huang, Shichun; McWilliams, Michael; Beeson, Melvin H.

2016-07-01

The Sugarloaf flow is a melilite nephelinite erupted from the Tantalus rift during rejuvenated-stage volcanism on O'ahu, the Honolulu Volcanics. The flow ponded in Mānoa Valley forming a ∼15 m thick flow which was cored and sampled in a quarry. Nepheline from a pegmatoid segregation in the flow yielded a 40Ar-39Ar age of 76 ka. This age, combined with others, indicates that the Tantalus rift eruptions are some of the youngest on O'ahu. Honolulu Volcanics erupt on average about every 35-40 ka indicating that future eruptions are possible. We evaluated the compositional variability of 19 samples from the flow, including 14 from the core. Twelve samples are representative of the bulk flow, four are dark- or light-colored variants, one is a heavy rare earth element (REE)-enriched pegmatoid, and two visually resemble the bulk flow, but have chemical characteristics of the dark and light variants. Our objective was to determine intraflow heterogeneity in mineralogy and composition. Variable abundances of Na2O, K2O, Sr, Ba, Rb, Pb and U in the flow were caused by post-eruptive mobility in a vapor phase, most likely during or soon after flow emplacement, and heterogeneous deposition of secondary calcite and zeolites. Relative to fine-grained samples, a pegmatoid vein that crosscuts the flow is enriched in incompatible trace elements except Sr and TiO2. Element mobility after eruption introduced scatter in trace element ratios including light-REE/heavy-REE, and all ratios involving mobile elements K, Rb, Ba, Sr, Pb, and U. Lavas from some of the 37 Honolulu Volcanics vents have crosscutting REE patterns in a primitive mantle-normalized plot. Such patterns have been interpreted to reflect variable amounts of residual garnet during partial melting. Previous studies of lavas from different vents concluded that garnet, phlogopite, amphibole, and Fe-Ti oxides were residual phases of the partial melting processes that created the Honolulu Volcanics (Clague and Frey, 1982; Yang et al., 2003). However post-eruptive processes in the Sugarloaf flow also produced crossing REE patterns. Eruptions on the Tantalus rift, including the Sugarloaf flow, produced volatile- and crystal-rich ash with interstitial glass and melt inclusions in olivine containing 4.2-6.4 wt% MgO compared to the flow average of 11.8 wt%. This flow erupted as a partially crystallized viscous magma at least 100 °C below its liquidus. The slow advance and cooling of the 15-m thick 'a' ā low promoted the segregation of pegmatoids, formation of light and dark bands with differing proportions of melilite and clinopyroxene, and induced volatile-enhanced mobility of incompatible elements.

Bioindicating potential of strontium contamination with Spanish moss Tillandsia usneoides.

PubMed

Zheng, Guiling; Pemberton, Robert; Li, Peng

2016-02-01

Tillandsia species have been recognized as efficient biomonitors of air pollution, but rarely exploited in bioindicating of strontium, an important nuclide. We exposed Tillandsia usneoides, colloquially known as Spanish moss due to its filamentous morphology but is an atypical angiosperm in the family Bromeliaceae, to the solutions with different Sr concentrations (0.1-100 mmol/L). The results showed that plants were able to endure Sr stress for a relatively long period, which suggests that T. usneoides is able to resist this toxic element. T. usneoides had the highest uptake ratio of Sr (82.21 ± 0.12%) when the plants were exposed to 0.1 mmol/L Sr solutions. Sr contents in T. usneoides increased significantly with the increase in applied metal solution concentrations. Low Sr stimulated the formation of chlorophyll, but high Sr decreased the contents of chlorophyll, and no significant effect on the total biomass was found in T. usneoides. In contrast, the permeability of plasma membrane based on the relative electronic conductivity in T. usneoides increased significantly under Sr stress, indicating that Sr probably caused oxidative stress. Moreover, correlation analysis showed that the leaf relative conductivity was significantly positively correlated with Sr contents in the plants after Sr treatments. Therefore, T. usneoides has considerable potential for monitoring Sr polluted environments through measuring Sr contents in the plant directly or exploiting the leaf relative conductivity as an indirect biomarker. Copyright © 2015 Elsevier Ltd. All rights reserved.

High-precision 87Sr/86Sr analyses in wines and their use as a geological fingerprint for tracing geographic provenance.

PubMed

Marchionni, Sara; Braschi, Eleonora; Tommasini, Simone; Bollati, Andrea; Cifelli, Francesca; Mulinacci, Nadia; Mattei, Massimo; Conticelli, Sandro

2013-07-17

The radiogenic isotopic compositions of inorganic heavy elements such as Sr, Nd, and Pb of the food chain may constitute a reliable geographic fingerprint, their isotopic ratios being inherited by the geological substratum of the territory of production. The Sr isotope composition of geomaterials (i.e., rocks and soils) is largely variable, and it depends upon the age of the rocks and their nature (e.g., genesis, composition). In this study we developed a high-precision analytical procedure for determining Sr isotopes in wines at comparable uncertainty levels of geological data. With the aim of verifying the possibility of using Sr isotope in wine as a reliable tracer for geographic provenance, we performed Sr isotope analyses of 45 bottled wines from four different geographical localities of the Italian peninsula. Their Sr isotope composition has been compared with that of rocks from the substrata (i.e., rocks) of their vineyards. In addition wines from the same winemaker but different vintage years have been analyzed to verify the constancy with time of the (87)Sr/(86)Sr. Sr isotope compositions have been determined by solid source thermal ionization mass spectrometry following purification of Sr in a clean laboratory. (87)Sr/(86)Sr of the analyzed wines is correlated with the isotopic values of the geological substratum of the vineyards, showing little or no variation within the same vineyard and among different vintages. Large (87)Sr/(86)Sr variation is observed among wines from the different geographical areas, reinforcing the link with the geological substratum of the production territory. This makes Sr isotopes a robust geochemical tool for tracing the geographic authenticity and provenance of wine.

Disentangling controls on element impurities of bivalve shells

NASA Astrophysics Data System (ADS)

Zhao, Liqiang; Schöne, Bernd R.; Mertz-Kraus, Regina

2017-04-01

Trace and minor elements of bivalve shells can potentially serve as proxies of past environmental change. However, retrieving environmental information from element impurities of bivalve shells remains an extremely challenging task. A central difficulty concerns the fact that extrinsic and intrinsic factors governing the element incorporation are poorly constrained. Within the framework of the ARAMACC project, we aim to decipher the complexity of the incorporation of trace and minor elements into bivalve shells and explore their full potential as proxies of environmental change. More specifically, the following questions were tackled. (1) How are trace and minor elements transported from the ambient environment to the calcifying front? (2) How is their incorporation into the shells affected by environmental and physiological variables? Our findings lend support to the general assumption that divalent ions (e.g., Cu2+, Mn2+, Zn2+ and Pb2+) share the same transport pathways as Ca2+ because of similar ionic radii and electrochemical properties. However, results obtained for Mg2+, Sr2+ and Ba2+ are particularly interesting as they are at odds with existing hypotheses on the incorporation of these three elements, i.e., intracellular Ca2+ pathways (via Ca2+ channels and Ca2+-ATPase) are likely not responsible for their incorporation. Despite the existence of strong physiological interference, some encouraging results were found, in particular (1) strong, positive relationships between the Sr, Ba and Mn contents of the shells and concentrations in the ambient water, (2) only minor effects of growth rate (which is closely linked to the rate of crystal growth and hence, kinetics) on the amounts of Na, Sr, Ba and Mn incorporation into the shells. Overall, our findings demonstrate that environmental and physiological controls on the element incorporation do not have to be mutually exclusive, i.e., if environmental changes outweigh physiological influences, one could still expect that trace and minor elements of bivalve shells serve as promising environmental proxies.

Sentence Repetition in Children with Specific Language Impairment: An Investigation of Underlying Mechanisms

ERIC Educational Resources Information Center

Riches, Nick G.

2012-01-01

Background: Sentence repetition (SR) is a reliable clinical marker of specific language impairment (SLI). However, little is known about cognitive processes underpinning SR, or areas of breakdown in children with SLI. Aims: The study investigated which cognitive mechanisms were most closely involved in SR performance: syntactic knowledge,…

Modulation of cutaneous scavenger receptor B1 levels by exogenous stressors impairs "in vitro" wound closure.

PubMed

Muresan, Ximena Maria; Sticozzi, Claudia; Belmonte, Giuseppe; Savelli, Vinno; Evelson, Pablo; Valacchi, Giuseppe

2018-06-01

Scavenger receptor B1 (SR-B1) is a trans-membrane protein, involved in tissue reverse cholesterol transport. Several studies have demonstrated that SR-B1 is also implicated in other physiological processes, such as bacteria and apoptotic cells recognition and regulation of intracellular tocopherol and carotenoids levels. Among the tissues where it is localized, SR-B1 has been shown to be significantly expressed in human epidermis. Our group has demonstrated that SR-B1 levels are down-regulated in human cultured keratinocytes by environmental stressors, such as cigarette smoke, via cellular redox imbalance. Our present study aimed to investigate whether such down-regulation was confirmed in a 3D skin model and under other environmental challengers such as particulate matter and ozone. We also investigated the association between oxidation-induced SR-B1 modulation and impaired wound closure. The data obtained showed that not only cigarette, but also the other environmental stressors reduced SR-B1 expression in epidermal cutaneous tissues and that this effect might be involved in impaired wound healing. Published by Elsevier B.V.

Petrogenesis of ore-bearing porphyry in non-subduction setting: a case study of the Eocene potassic intrusions in the western Yangtze Block

NASA Astrophysics Data System (ADS)

Liu, Zheng; Liao, Shi-Yong; Zhou, Qing; Zhang, Xin

2018-05-01

In the western Yangtze Block, abundant Eocene ( 38-34 Ma) potassic adakite-like intrusions and associated porphyry copper deposits are exposed in non-subduction setting, including Machangjing, Beiya, Binchuan, Habo and Tongchang intrusions. All these ore-bearing porphyries share many geochemical characteristics of adakite such as depletion in heavy rare earth elements (HREEs), enrichment in Sr and Ba, absence of negative Eu anomalies, high SiO2, Al2O3, Sr/Y, La/Yb and low Y, Yb contents. They also exhibit affinities of potassic rocks, e.g., alkali-rich, high K2O/Na2O ratios and enrichment in light rare earth elements (LREEs) and large ion lithophile elements (LILEs). Their Sr-Nd isotopic ratios are similar to coeval shoshonitic lamprophyres. Geochemical data indicate that they were probably produced by partial melting of newly underplated potassic rocks sourced from a modified and enriched lithospheric mantle. These underplated rocks have elevated oxygen fugacity, water and copper contents, with high metallogenic potential. We propose that all the studied potassic rocks were emplaced in a post-collisional setting, associated with the local removal of lithospheric mantle.

Fluid-rock interaction during a large earthquake recorded in fault gouge: A case study of the Nojima fault, Japan

NASA Astrophysics Data System (ADS)

Bian, D.; Lin, A.

2016-12-01

Distinguishing the seismic ruptures during the earthquake from a lot of fractures in borehole core is very important to understand rupture processes and seismic efficiency. In particular, a great earthquake like the 1995 Mw 7.2 Kobe earthquake, but again, evidence has been limited to the grain size analysis and the color of fault gouge. In the past two decades, increasing geological evidence has emerged that seismic faults and shear zones within the middle to upper crust play a crucial role in controlling the architectures of crustal fluid migration. Rock-fluid interactions along seismogenic faults give us a chance to find the seismic ruptures from the same event. Recently, a new project of "Drilling into Fault Damage Zone" has being conducted by Kyoto University on the Nojima Fault again after 20 years of the 1995 Kobe earthquake for an integrated multidisciplinary study on the assessment of activity of active faults involving active tectonics, geochemistry and geochronology of active fault zones. In this work, we report on the signature of slip plane inside the Nojima Fault associated with individual earthquakes on the basis of trace element and isotope analyses. Trace element concentrations and 87Sr/86Sr ratios of fault gouge and host rocks were determined by an inductively coupled plasma mass spectrometer (ICP-MS) and thermal ionization mass spectrometry (TIMS). Samples were collected from two trenches and an outcrop of Nojima Fault which. Based on the geochemical result, we interpret these geochemical results in terms of fluid-rock interactions recorded in fault friction during earthquake. The trace-element enrichment pattern of the slip plane can be explained by fluid-rock interactions at high temperature. It also can help us find the main coseismic fault slipping plane inside the thick fault gouge zone.

Preparation and properties of Ba xSr 1- xCo yFe 1- yO 3- δ cathode material for intermediate temperature solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Zhao, Hailei; Shen, Wei; Zhu, Zhiming; Li, Xue; Wang, Zhifeng

Ba xSr 1- xCo yFe 1- yO 3- δ (BSCF) materials with perovskite structure were synthesized via solid-state reaction. Their structural characteristics, electrical-conduction behavior and cathode performance were investigated. Compared to A-site elements, B-site elements show a wide solid-solution range in BSCF. The electrical-conduction behavior of BSCF obeys the small polaron-hopping mechanism. An increase of Ba or Co content in the BSCF samples results in a decrease of electrical conductivity, which is mainly attributable to the preferential existence of B 3+ rather than B 4+ in Ba- or Co-rich samples. At the same time, this leads to increases in the lattice parameter a and the number of oxygen vacancies. BSCF samples with high Ba content show a high structural stability (high oxygen-loss temperature). Ba 0.6Sr 0.4Co 0.8Fe 0.2O 3- δ and Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3- δ materials present good thermal-cycling stability of the electrical conductivity. Compared with Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3- δ, Ba 0.6Sr 0.4Co 0.8Fe 0.2O 3- δ exhibits a better cathode performance in a Ce 0.8Gd 0.2O 2- δ (GDC)-supported half cell. The cell performance can be improved by introducing a certain amount of GDC electrolyte into the BSCF cathode material.

Petrology and geochronology of metamorphosed volcanic rocks and a middle Cretaceous volcanic neck in the east-central Sierra Nevada, California.

USGS Publications Warehouse

Kistler, R.W.; Swanson, S.E.

1981-01-01

Metamorphosed Mesozoic volcanic rocks from the E-central Sierra Nevada range in composition from basalt to rhyolite and have ages, based on whole rock Rb-Sr and U-Pb zircon dating, of about 237- 224, 185, 163, 134, and 100Ma. The major plutons of the batholith in this area are of Triassic (215-200Ma) and Cretaceous (94-80Ma) ages. Initial 87Sr/86Sr values for the metamorphosed volcanic rocks of the area are in the range from 0.7042 to 0.7058 and are generally different from the values for the surrounding batholithic rocks (0.7056-0.7066). A circular, zoned granitic pluton, with an outcrop area of 2.5km2, similar in appearance to a ring dike complex, was apparently a conduit for some or possibly all of the middle-Cretaceous metamorphosed volcanic rocks exposed about 5km to the S in the western part of the Ritter Range. Samples from the metamorphosed volcanic rocks and the pluton yield a Rb/Sr whole rock isochron age of 99.9+ or -2.2Ma with an intitial 87Sr/86Sr of 0.7048+ or -0.00001. Major element variation diagrams of the pluton and volcanic rocks define coincident compositional trends. The ages of volcanic events relative to the ages of the major intrusive epochs and the major element and isotopic compositions of the volcanic rocks relative to the major plutons indicate that the volcanic rocks are not simply or directly related to the major plutons in the Sierra Nevada. -from Authors

Pb, Sr, and Nd isotopic compositions of a suite of Large Archean, igneous rocks, eastern Beartooth Mountains - Implications for crust-mantle evolution

NASA Technical Reports Server (NTRS)

Wooden, J. L.; Mueller, P. A.

1988-01-01

Compositionally diverse Late Archean rocks (2.74-2.79 Ga old) from the eastern Beartooth Mountains (Montana and Wyoming) were studied and shown to have the same initial Pb, Sr, and Nd isotopic ratios. Lead and Sr initial ratios are higher and Nd initial values lower than predicted for rocks derived from model mantle sources and strongly indicate the involvement of an older crustal reservoir in the genesis of these rocks. A model involving subduction of continental detritus and contamination of the overlying mantle is suggested.

Investigation of the Influence of Selected Soil and Plant Properties from Sakarya, Turkey, on the Bioavailability of Trace Elements by Applying an In Vitro Digestion Model.

PubMed

Altundag, Huseyin; Albayrak, Sinem; Dundar, Mustafa S; Tuzen, Mustafa; Soylak, Mustafa

2015-11-01

The main aim of this study was an investigation of the influence of selected soil and plant properties on the bioaccessibility of trace elements and hence their potential impacts on human health in urban environments. Two artificial digestion models were used to determine trace element levels passing from soil and plants to man for bioavailability study. Soil and plant samples were collected from various regions of the province of Sakarya, Turkey. Digestive process is started by addition of soil and plant samples to an artificial digestion model based on human physiology. Bioavailability % values are obtained from the ratio of the amount of element passing to human digestion to element content of soil and plants. According to bioavailability % results, element levels passing from soil samples to human digestion were B = Cr = Cu = Fe = Pb = Li < Al < Ni < Co < Ba < Mn < Sr < Cd < Na < Zn < Tl, while element levels passing from plant samples to human digestion were Cu = Fe = Ni = Pb = Tl = Na = Li < Co < Al < Sr < Ba < Mn < Cd < Cr < Zn < B. It was checked whether the results obtained reached harmful levels to human health by examining the literature.

Timescale of Petrogenetic Processes Recorded in the Mount Perkins Magma System, Northern Colorado River Extension Corridor, Arizona

NASA Technical Reports Server (NTRS)

Danielson, Lisa R.; Metcalf, Rodney V.; Miller, Calvin F.; Rhodes Gregory T.; Wooden, J. L.

2013-01-01

The Miocene Mt. Perkins Pluton is a small composite intrusive body emplaced in the shallow crust as four separate phases during the earliest stages of crustal extension. Phase 1 (oldest) consists of isotropic hornblende gabbro and a layered cumulate sequence. Phase 2 consists of quartz monzonite to quartz monzodiorite hosting mafic microgranitoid enclaves. Phase 3 is composed of quartz monzonite and is subdivided into mafic enclave-rich zones and enclave-free zones. Phase 4 consists of aphanitic dikes of mafic, intermediate and felsic compositions hosting mafic enclaves. Phases 2-4 enclaves record significant isotopic disequilibrium with surrounding granitoid host rocks, but collectively enclaves and host rocks form a cogenetic suite exhibiting systematic variations in Nd-Sr-Pb isotopes that correlate with major and trace elements. Phases 2-4 record multiple episodes of magma mingling among cogenetic hybrid magmas that formed via magma mixing and fractional crystallization at a deeper crustal. The mafic end-member was alkali basalt similar to nearby 6-4 Ma basalt with enriched OIB-like trace elements and Nd-Sr-Pb isotopes. The felsic end-member was a subalkaline crustal-derived magma. Phase 1 isotropic gabbro exhibits elemental and isotopic compositional variations at relatively constant SiO2, suggesting generation of isotropic gabbro by an open-system process involving two mafic end-members. One end-member is similar in composition to the OIB-like mafic end-member for phases 2-4; the second is similar to nearby 11-8 Ma tholeiite basalt exhibiting low epsilon (sub Nd), and depleted incompatible trace elements. Phase 1 cumulates record in situ fractional crystallization of an OIB-like mafic magma with isotopic evidence of crustal contamination by partial melts generated in adjacent Proterozoic gneiss. The Mt Perkins pluton records a complex history in a lithospheric scale magma system involving two distinct mantle-derived mafic magmas and felsic magma sourced in the crust. Mixing and fractional crystallization of these magmas at various levels in the crust generated a suite of intermediate composition magmas. U-Pb zircon SHRIMP ages of phase 1 (15.7 +/- 0.2 Ma), phase 3 (15.8 +/- 0.2 Ma) and phase 4 (15.4 +/- 0.3 Ma) document a 100-300k year timescale for petrogenetic processes recorded in the Mt Perkins magma system.

Laser-induced breakdown spectroscopy for elemental characterization of calcitic alterations on cave walls.

PubMed

Bassel, Léna; Motto-Ros, Vincent; Trichard, Florian; Pelascini, Frédéric; Ammari, Faten; Chapoulie, Rémy; Ferrier, Catherine; Lacanette, Delphine; Bousquet, Bruno

2017-01-01

Cave walls are affected by different kinds of alterations involving preservative issues in the case of ornate caves, in particular regarding the rock art covering the walls. In this context, coralloids correspond to a facies with popcorn-like aspect belonging to the speleothem family, mostly composed of calcium carbonate. The elemental characterization indicates the presence of elements that might be linked to the diagenesis and the expansion of the alterations as demonstrated by prior analyses on stalagmites. In this study, we report the use of laser-induced breakdown spectroscopy (LIBS) to characterize the elemental composition of one coralloid sample with a portable instrument allowing punctual measurements and a laboratory mapping setup delivering elemental images with spatial resolution at the micrometric scale, being particularly attentive to Mg, Sr, and Si identified as elements of interest. The complementarity of both instruments allows the determination of the internal structure of the coralloid. Although a validation based on a reference technique is necessary, LIBS data reveal that the external layer of the coralloid is composed of laminations correlated to variations of the LIBS signal of Si. In addition, an interstitial layer showing high LIBS signals for Fe, Al, and Si is interpreted to be a detrital clay interface between the external and the internal part of the coralloid. These preliminary results sustain a possible formation scenario of the coralloid by migration of the elements from the bedrock.

Minor elements incorporation control by ionic radius and growth rate on a stalagmite from the Chauvet Cave (SE-France)

NASA Astrophysics Data System (ADS)

Bourdin, C.; Douville, E.; Genty, D.

2009-12-01

A multi-elemental study focusing on earth-alkalis (Mg, Ca, Sr and Ba), uranium and rare-earth elements (REE) in the calcite of a stalagmite from the Chauvet Cave (SE of France) has been achieved by ICP-MS. The Chau-stm6 stalagmite which grew from 33 to 11.5 ky had already been dated and the published d13C and d18O profile is used as a paleoclimatic benchmark. Ba and Sr profiles show an abrupt concentration increase at the beginning of the last deglaciation whereas U and Mg feature a decreasing trend. REY (REE+yttrium) concentrations decrease markedly during early deglaciation (between 15 and 14.5 ky). The transition corresponds to a change from a slow to a fast growth rate. These variations can be explained by the crystallographic control of ionic radii of the minor elements: incorporation of small ions compared to Ca such as U, Mg, heavy REE are favoured during slow growth period (i.e. glacial) whereas large ions such as Ba, Sr and light REE are preferentially precipitated during fast growth period (i.e. Bolling-Allerod). This crystallographic effect seems to be dominant here because the soil above the cave is sparse. And may not have played a major role on the opposite to the water-limestone interaction.

Geochemical evolution of Kohala Volcano, Hawaii

USGS Publications Warehouse

Lanphere, M.A.; Frey, F.A.

1987-01-01

Kohala Volcano, the oldest of five shield volcanoes comprising the island of Hawaii, consists of a basalt shield dominated by tholeiitic basalt, Pololu Volcanics, overlain by alkalic lavas, Hawi Volcanics. In the upper Pololu Volcanics the lavas become more enriched in incompatible elements, and there is a transition from tholeiitic to alkalic basalt. In contrast, the Hawi volcanics consist of hawaiites, mugearites, and trachytes. 87Sr/86Sr ratios of 14 Pololu basalts and 5 Hawi lavas range from 0.70366 to 0.70392 and 0.70350 to 0.70355, respectively. This small but distinct difference in Sr isotopic composition of different lava types, especially the lower 87Sr/86Sr in the younger lavas with higher Rb/Sr, has been found at other Hawaiian volcanoes. Our data do not confirm previous data indicating Sr isotopic homogeneity among lavas from Kohala Volcano. Also some abundance trends, such as MgO-P2O5, are not consistent with a simple genetic relationship between Pololu and Hawi lavas. We conclude that all Kohala lavas were not produced by equilibrium partial melting of a compositionally homogeneous source. ?? 1987 Springer-Verlag.

Strontium administration in young chickens improves bone volume and architecture but does not enhance bone structural and material strength.

PubMed

Shahnazari, M; Lang, D H; Fosmire, G J; Sharkey, N A; Mitchell, A D; Leach, R M

2007-03-01

Genetic selection for rapid body growth in broiler chickens has resulted in adverse effects on the skeletal system exemplified by a higher rate of cortical fractures in leg bones. Strontium (Sr) has been reported to have beneficial effects on bone formation and strength. We supplemented the diet of 300-day-old chicks with increasing dosages of Sr (0%, 0.12%, or 0.24%) to study the capacity of the element to improve bone quality and mechanical integrity. Treatment with Sr increased cortical bone volume and reduced bone porosity as measured by micro-computed tomography. The higher level of Sr significantly reduced bone Ca content (34.7%) relative to controls (37.2%), suggesting that Sr replaced some of the Ca in bone. Material properties determined by the three-point bending test showed that bone in the Sr-treated groups withstood greater deformation prior to fracture. Load to failure and ultimate stress were similar across groups. Our results indicate that Sr treatment in rapidly growing chickens induced positive effects on bone volume but did not improve the breaking strength of long bones.

Cs-137 and Sr-90 level in diary products

NASA Astrophysics Data System (ADS)

Petukhov, V. L.; Gorb, T. S.; Petukhov, I. V.; Dukhanov, Yu. A.; Sevryuk, I. Z.; Patrashkov, S. A.; Korotkevich, O. S.

2003-05-01

About 70% of radioactive substances fell on the territory of the Byelorussia Republic after the Chernobyl Atom Power Station Disaster. Cs-137 and Sr-90 accumulation dynamics was studied in milk of the cows from the highest polluted Braginsky area. 408 milk samples of Black and White cows were investigated. In 1995 average Cs-137 and Sr-90 levels were 61.00 and 3.73 Bk/dm^3 respectively. Cs-137 and Sr-90 levels exceeded Byelorussia Republic upperlimits RDU 96 in 10 and 50% of milk samples respectively. After 5 years (by 2000) Cs-137 and Sr-90 levels had become almost 3 and 2 times less (21.70 Bk/dm^3 and 1.72 Bk/dm^3 respectively). Cs-137 and Sr-90 levels exceeded RDU 96 in 1.5 and 5.5% of milk samples respectively. In the same periods Cs-137 and Sr-90 levels were 7 and 2 times higher than the similar indexes in the relatively clean Novosibirsk area. Thus, radioactive element levels in milk of Black and White cows of the Byelorussia Republic decreased significantly for the past years.

Geographical traceability based on 87Sr/86Sr indicator: a first approach for PDO Lambrusco wines from Modena.

PubMed

Durante, Caterina; Baschieri, Carlo; Bertacchini, Lucia; Cocchi, Marina; Sighinolfi, Simona; Silvestri, Michele; Marchetti, Andrea

2013-12-01

The main goal of this study was to evaluate (87)Sr/(86)Sr ratio in different matrices, namely soils, branches, and grape juices, of an oenological food chain in order to develop a robust analytical strategy able to link the investigated food to its territory of origin. The (87)Sr/(86)Sr has been used as traceability marker and several aspects, affected its variability, i.e. geological features of the investigated area, the bio-available fraction of elements in the soils and the up-take of the plant, have been taken into account. Optimisation of an analytical procedure for the separation of Sr from its interferences and investigation of the analytical performances in terms of precision of used methodology have been carried out as well. This work highlighted a good match between the isotopic values monitored in the bio-available fraction of soils and their respective grape juices for almost all the investigated areas. The correlation with food satisfyingly improves when isotopic relative abundance values of branches vine are considered. Copyright © 2013 Elsevier Ltd. All rights reserved.

Imaging and tuning polarity at SrTiO3 domain walls

NASA Astrophysics Data System (ADS)

Frenkel, Yiftach; Haham, Noam; Shperber, Yishai; Bell, Christopher; Xie, Yanwu; Chen, Zhuoyu; Hikita, Yasuyuki; Hwang, Harold Y.; Salje, Ekhard K. H.; Kalisky, Beena

2017-12-01

Electrostatic fields tune the ground state of interfaces between complex oxide materials. Electronic properties, such as conductivity and superconductivity, can be tuned and then used to create and control circuit elements and gate-defined devices. Here we show that naturally occurring twin boundaries, with properties that are different from their surrounding bulk, can tune the LaAlO3/SrTiO3 interface 2DEG at the nanoscale. In particular, SrTiO3 domain boundaries have the unusual distinction of remaining highly mobile down to low temperatures, and were recently suggested to be polar. Here we apply localized pressure to an individual SrTiO3 twin boundary and detect a change in LaAlO3/SrTiO3 interface current distribution. Our data directly confirm the existence of polarity at the twin boundaries, and demonstrate that they can serve as effective tunable gates. As the location of SrTiO3 domain walls can be controlled using external field stimuli, our findings suggest a novel approach to manipulate SrTiO3-based devices on the nanoscale.

Ag loading induced visible light photocatalytic activity for pervoskite SrTiO3 nanofibers

NASA Astrophysics Data System (ADS)

Wu, Yeqiu; He, Tao

2018-06-01

The synthesis and photocatalytic activities of Ag-SrTiO3 nanofibers were reported in this work. The fabricated Ag-SrTiO3 nanofibers were characterized by TG-DSC, XRD, IR, XPS, SEM, TEM, DRS and ESR techniques. The XRD and IR results show that Ag-SrTiO3 nanofibers have a perovskite structure after the heat treatment at 700 °C. The XPS result shows that Ag element exists as Ag0 in the fabricated Ag-SrTiO3 nanofibers. The SEM and TEM images indicate the obtaining of nanofibers with porous structure. The photocatalytic activity of Ag-SrTiO3 nanofibers was evaluated by degrading RhB and MB under visible light irradiation. The Ag-SrTiO3 nanofibers show excellent photocatalytic activity under visible light irradiation because of the surface plasmon resonance effect of Ag0. In the photocatalysis process of RhB and MB, lots of hydroxyl radicals were generated, which plays the key role in the decomposition of organic pollutants.

Ag loading induced visible light photocatalytic activity for pervoskite SrTiO3 nanofibers.

PubMed

Wu, Yeqiu; He, Tao

2018-06-15

The synthesis and photocatalytic activities of Ag-SrTiO 3 nanofibers were reported in this work. The fabricated Ag-SrTiO 3 nanofibers were characterized by TG-DSC, XRD, IR, XPS, SEM, TEM, DRS and ESR techniques. The XRD and IR results show that Ag-SrTiO 3 nanofibers have a perovskite structure after the heat treatment at 700°C. The XPS result shows that Ag element exists as Ag 0 in the fabricated Ag-SrTiO 3 nanofibers. The SEM and TEM images indicate the obtaining of nanofibers with porous structure. The photocatalytic activity of Ag-SrTiO 3 nanofibers was evaluated by degrading RhB and MB under visible light irradiation. The Ag-SrTiO 3 nanofibers show excellent photocatalytic activity under visible light irradiation because of the surface plasmon resonance effect of Ag 0 . In the photocatalysis process of RhB and MB, lots of hydroxyl radicals were generated, which plays the key role in the decomposition of organic pollutants. Copyright © 2018 Elsevier B.V. All rights reserved.

Scavenging of oxygen from SrTiO3 by metals and its implications for oxide thin film deposition

NASA Astrophysics Data System (ADS)

Posadas, Agham; Kormondy, Kristy; Guo, Wei; Ponath, Patrick; Kremer, Jacqueline; Hadamek, Tobias; Demkov, Alexander

SrTiO3 is a widely used substrate for the growth of other functional oxide thin films. However, SrTiO3 loses oxygen very easily during oxide thin film deposition even under relatively high oxygen pressures. In some cases, there will be an interfacial layer of oxygen-deficient SrTiO3 formed at the interface with the deposited oxide film, depending on the metals present in the film. By depositing a variety of metals layer by layer and measuring the evolution of the core level spectra of both the deposited metal and SrTiO3 using x-ray photoelectron spectroscopy, we show that there are three distinct types of behavior that occur for thin metal films on SrTiO3. We discuss the implications of these types of behavior for the growth of complex oxide thin films on SrTiO3, and which oxide thin films are expected to produce an interfacial oxygen-deficient layer depending on their elemental constituents.

Micro-X-ray fluorescence-based comparison of skeletal structure and P, Mg, Sr, O and Fe in a fossil of the cold-water coral Desmophyllum sp., NW Pacific

NASA Astrophysics Data System (ADS)

Yoshimura, Toshihiro; Suzuki, Atsushi; Tamenori, Yusuke; Kawahata, Hodaka

2014-02-01

Micro-scale distributions of trace and minor elements in, for example, coral skeletons are crucial as geochemical tracers of past environmental conditions, because they have the inherent advantage of accounting for confounding diagenetic and physiological effects. To extract reproducible paleoceanographic records from coral skeletons, a selective measurement of specific ultrastructures at high spatial resolution is required. Compared to warm-water reef-building corals, such data are limited in cold-water corals and, to the best of the authors' knowledge, the latter have to date not been examined by means of micro-X-ray fluorescence. This technique was used for micrometer-scale imaging of P, Mg, Sr, O, and Fe intensities (counts per unit time) in a fossil specimen (as yet unknown age) of the cold-water coral Desmophyllum sp. from surface sediments of the NW Pacific. Cross plots confirmed that the micro-XRF signals were associated with corresponding trends in elemental concentration (ppm). Two major structural components of the septum—centers of calcification (COCs) and the surrounding fibrous aragonite portion—differed in composition. The COCs were characterized by higher intensities of P and Mg (650 and 220 counts per 5 s, respectively), and lower intensities of Sr (2,800) and O (580; corresponding values for the fibrous aragonite are 370, 180, 3,300 and 620 counts per 5 s, respectively). Oxygen intensity values were mostly homogeneous, but slightly lower in COCs and substantially higher in a well-defined patch in the fibrous aragonite. The mostly homogeneous P signals in the fibrous aragonite confirm the utility of this structural component and of coral septa in general for tracer studies of oceanic P. Nevertheless, spot occurrences of elevated P (>950 counts per 5 s) spanning tens of micrometers in specific parts of the fibrous region of the septum would cause overestimates of oceanic P, and should evidently not be overlooked in future research. The distribution of Fe showed no correlation with P, indicating no significant contamination in the form of P-bearing diagenetic ferromanganese precipitates. Such hotspots plausibly reflect the presence of other mineral phases, such as crystalline hydroxylapatite inclusions or contamination with organic material. The P signal intensity was positively correlated with Mg ( r=0.553, p<0.001), and negatively with Sr ( r=-0.489, p<0.001) and O ( r=-0.311, p<0.001). There was no discernible evidence of control by water temperature in the Sr distribution pattern. These findings establish micro-X-ray fluorescence as a highly suitable pre-screening tool in cold-water coral sclerochronology, which can serve to refine sampling strategies without sample damage, and complement other micrometer-scale spatial distribution analyses of elements (notably, Ca) based on well-known approaches involving micro-milling, electron microprobes, secondary ion mass spectrometry, and laser ablation.

Sr isotope variations in the Carnian-Norian succession at Pizzo Mondello, Sicani Mountains, Sicily

NASA Astrophysics Data System (ADS)

Onoue, T.; Yamashita, K.; Rigo, M.; Abate, B.

2017-12-01

The Norian stage in the Late Triassic is exceptionally long (23 Myr) and was subdivided into three substages: the Lacian, Alaunian, and Sevatian. In order to infer the Norian environmental changes in the western Tethys Ocean, the stratigraphic variations of 87Sr/86Sr in the Upper Triassic limestone succession in Sicily were examined. The Pizzo Mondello section studied here mainly consists of a pelagic carbonate sequence of the Scillato Formation, and ranges in age from Tuvalian (late Carnian) to Rhaetian. The Scillato Formation represents a deep-water pelagic facies deposited along the Sicanian Basin in the western Tethys Ocean. We selected fine-grained limestone samples from both the microfacies of lime-mudstone and wackestone to approximate the primary 87Sr/86Sr signature of the limestone beds. The 87Sr/86Sr values are relatively constant in the Tuvalian and Lacian (early Norian). However, the remarkable rise in 87Sr/86Sr occurred across the Lacian-Alaunian (early-middle Norian) transition. Variations in 87Sr/86Sr values show an increasing trend in 87Sr/86Sr from 0.7077 at the base of Lacian to 0.7080 in the Sevatian (late Norian). In the Sevatian, the 87Sr/86Sr ratios display a sudden negative excursion toward lower values and show a relatively quick recovery to pre-excursion 87Sr/86Sr ratios. Korte et al. (2003) suggested that the rise in the 87Sr/86Sr values from the middle Carnian to the late Norian coincide with the Cimmerian orogeny. Our new 87Sr/86Sr data from the Pizzo Mondello section reveal a comparable trend, with a sharp increase in 87Sr/86Sr within the Alaunian, suggesting the rapid uplift and erosion in the Cimmerian Mountains at this time. The cause of the 87Sr/86Sr excursion in the Sevatian remains uncertain. However, the biostratigraphic record of conodonts suggests that a morphological evolution towards platform-less elements occurred with the beginning of the Sr-isotope excursion.

Elemental and Sr-Nd isotopic geochemistry of Cretaceous to Early Paleogene granites and volcanic rocks in the Sikhote-Alin Orogenic Belt (Russian Far East): implications for the regional tectonic evolution

NASA Astrophysics Data System (ADS)

Zhao, Pan; Jahn, Bor-ming; Xu, Bei

2017-09-01

The Sikhote-Alin Orogenic Belt in Russian Far East is an important Late Mesozoic to Early Cenozoic accretionary orogen related to the subduction of the Paleo-Pacific Plate. This belt was generated by successive accretion of terranes made of accretionary prisms, turbidite basins and island arcs to the continental margin of northeastern Asia (represented by the Bureya-Jiamusi-Khanka Block) from Jurassic to Late Cretaceous. In order to study the tectonic and crustal evolution of this orogenic belt, we carried out zircon U-Pb dating, and whole-rock elemental and Sr-Nd isotopic analyses on granites and volcanic rocks from the Primorye region of southern Sikhote-Alin. Zircon dating revealed three episodes of granitoid emplacement: Permian, Early Cretaceous and Late Cretaceous to Early Paleogene. Felsic volcanic rocks (mainly rhyolite, dacite and ignimbrite) that overlay all tectonostratigraphic terranes were erupted during 80-57 Ma, postdating the accretionary process in the Sikhote-Alin belt. The Cretaceous-Paleogene magmatism represents the most intense tectonothermal event in the Sikhote-Alin belt. Whole-rock major and trace elemental data show arc-like affinity for granitoids and volcanic rocks, indicating that they were likely generated in a supra-subduction setting. Their initial 87Sr/86Sr ratios range from 0.7048 to 0.7114, and εNd(t) values vary from +1.7 to -3.8 (mostly < 0). Thus, the elemental and Sr-Nd isotopic data suggest that the felsic magmas were generated by partial melting of source rocks comprising mantle-derived juvenile component and recycled crustal component. In addition to the occurrence in the Sikhote-Alin orogenic belt, Cretaceous to Early Paleogene magmatic rocks are also widespread in NE China, southern Korean peninsula, Japanese islands and other areas of Russian Far East, particularly along the coastal regions of the Okhotsk and Bering Seas. These rocks constitute an extended magmatic belt along the continental margin of NE Asia. The generation of this belt was ascribed to subduction of the Paleo-Pacific Plate.

The timing of alkali metasomatism in paleosols

NASA Technical Reports Server (NTRS)

MacFarlane, A. W.; Holland, H. D.

1991-01-01

We have measured the concentrations of rubidium and strontium and 87Sr/86Sr values of whole-rock samples from three paleosols of different ages. The oldest of the three weathering horizons, the 2,760 Ma Mt. Roe #1 paleosol in the Fortescue Group of Western Australia, experienced addition of Rb, and probably Sr, at 2,168 +/- 10 Ma. The intermediate paleosol, developed on the Hekpoort Basalt in South Africa, is estimated to have formed at 2,200 Ma, and yields a Rb-Sr isochron age of 1,925 +/- 32 Ma. The youngest of the three paleosols, developed on the Ongeluk basalt in Griqualand West, South Africa ca. 1,900 Ma, yielded a Rb-Sr age of 1,257 +/- 11 Ma. The Rb-Sr systematics of all three paleosols were reset during post-weathering metasomatism related to local or regional thermal disturbances. The Rb-Sr systematics of the paleosols were not subsequently disturbed. The near-complete removal of the alkali and alkaline earth elements from these paleosols during weathering made them particularly susceptible to resetting of their Rb-Sr systematics. Paleosols of this type are therefore sensitive indicators of the timing of thermal disturbances.

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

Li, Chen; Shen, Xuan; Yang, Yurong

Perovskite RAlO 3 (R = La, Nd, Sm, and Gd) films have been deposited epitaxially on (001) TiO 2-terminated SrTiO 3 substrates. In this paper, it is observed that the two-dimensional transport characteristics at the RAlO 3/SrTiO 3 interfaces are very sensitive to the species of rare-earth element, that is to chemical strain. Although electron energy loss spectroscopy measurements show that electron transfer occurs in all the four polar/nonpolar heterostructures, the amount of electrons transferred across SmAlO 3/SrTiO 3 and GdAlO 3/SrTiO 3 interfaces are much less than those across LaAlO 3/SrTiO 3 and NdAlO 3/SrTiO 3 interfaces. First-principles calculationsmore » reveal the competition between ionic polarization and electronic polarization in the polar layers in compensating the build-in polarization due to the polar discontinuity at the interface. Finally, in particular, a large ionic polarization is found in SmAlO 3/SrTiO 3 and GdAlO 3/SrTiO 3 systems (which experience the largest tensile epitaxial strain), hence reducing the amount of electrons transferred.« less

Characterizing the Effect of Shock on Isotopic Ages. 2; Mg-Suite Troctolite Major Elements

NASA Technical Reports Server (NTRS)

Edmunson, Jennifer; Cohen, Barbara

2009-01-01

Two troctolites from the lunar magnesium suite (Mg-suite), 76335 and 76535, have Sm-147-ND-143 and Rb-87- Sr-87 ages that do not indicate the same age for their respective sample. In the case of 76335, the Sm-147-ND-143 age is 4278 +/- 60 Ma, but the Rb-87-Sr-87 data does not reveal an isochron]. For 76535, the Sm-147-ND-143 age is significantly younger (4260 +/- 60 Ma) than the Rb-87- Sr-87 age (4570 +/- 70 Ma, Lambda = 1.402x10(exp -11)). This study was designed to discover why the Sm-147-ND-143 and Rb-87-Sr-87 ages did not match for each individual sample.

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.

Rapid Phenotyping Adult Plant Resistance to Stem Rust in Wheat Grown under Controlled Conditions.

PubMed

Riaz, Adnan; T Hickey, Lee

2017-01-01

Stem rust (SR) or black rust caused by Puccinia graminis f. sp. tritici is one of the most common diseases of wheat (Triticum aestivum L.) crops globally. Among the various control measures, the most efficient and sustainable approach is the deployment of genetically resistant cultivars. Traditionally, wheat breeding programs deployed genetic resistance in cultivars, but unknowingly this is often underpinned by a single seedling resistance gene, which is readily overcome by the pathogen. Nowadays, adult plant resistance (APR) is a widely adopted form of rust resistance because more durable mechanisms often underpin it. However, only a handful of SR APR genes are available, so breeders currently strive to combine seedling and APR genes. Phenotyping adult wheat plants for resistance to SR typically involves evaluation in the field. But establishing a rust nursery can be challenging, and screening is limited to once a year. This slows down research efforts to isolate new APR genes and breeding of genetically resistant cultivars.In this study, we report a protocol for rapid evaluation of adult wheat plants for resistance to stem rust. We demonstrate the technique by evaluating a panel of 16 wheat genotypes consisting of near isogenic lines (NILs) for known Sr genes (i.e., Sr2, Sr33, Sr45, Sr50, Sr55, Sr57, and Sr58) and three landraces carrying uncharacterized APR from the N. I. Vavilov Institute of Plant Genetic Resources (VIR). The method can be completed in just 10 weeks and involves two inoculations: first conducted at seedling stage and a second at the adult stage (using the same plants). The technique can detect APR, such as that conferred by APR gene Sr2, along with pseudo-black chaff (the morphological marker). Phenotyping can be conducted throughout the year, and is fast and resource efficient. Further, the phenotyping method can be applied to screen breeding populations or germplasm accessions using local or exotic races of SR.

Chondritic late accretion to Mars and the nature of shergottite reservoirs

NASA Astrophysics Data System (ADS)

Tait, Kim T.; Day, James M. D.

2018-07-01

Mars is considered to have formed as a planetary embryo that experienced extensive differentiation early in its history. Shergottite meteorites preserve evidence for this history, and for late accretion events that affected their mantle sources within Mars. Here we report the first coupled 187Re-187Os, 87Sr/86Sr, highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re) and major element abundance dataset for martian shergottites that span a range of MgO contents, from 6.4 to 30.3 wt.%. The shergottites range from picro-basalt to basaltic-andesite compositions, have enriched to depleted incompatible trace-element compositions, and define fractional crystallization trends, enabling the determination of HSE compatibility for martian magmatism in the order: Os > Ir ≥ Ru ≫ Pt ≥ Pd ≥ Re. This order of compatibility is like that defined previously for Earth and the Moon, but the fractionation of strongly compatible Os, Ir and Ru appears to take place at higher MgO contents in martian magmas, due to early onset of sulfide fractionation. In general, enriched shergottites have lower MgO contents than intermediate or depleted shergottites and have fractionated HSE patterns (Re + Pd + Pt > Ru + Ir + Os) and more radiogenic measured 87Sr/86Sr (0.7127-0.7235) and 187Os/188Os (0.140-0.247) than intermediate or depleted shergottite meteorites (87Sr/86Sr = 0.7010-0.7132; 187Os/188Os = 0.127-0.141). Osmium isotope compositions, corrected for crystallization age, define compositions that are implausibly unradiogenic in some enriched shergottites, implying recent mobilization of Re in some samples. Filtering for the effects of alteration and high Re/Os through crystal-liquid fractionation leads to a positive correlation between age-corrected Sr and Os isotope compositions. Mixing between hypothetical martian crustal and mantle reservoirs are unable to generate the observed Sr-Os isotope compositions of shergottites, which require either distinct and discrete long-term incompatible-element depleted and enriched mantle sources, or originate from hybridized melting of deep melts with metasomatized martian lithosphere. Using MgO-regression methods, we obtain a modified estimate of the bulk silicate Mars HSE composition of (in ng g-1) 0.4 [Re], 7.4 [Pd], 9.6 [Pt], 6.2 [Ru], 3.7 [Ir], 4 [Os], and a long-term chondritic 187Os/188Os ratio (∼0.1312). This result does not permit existing models invoking high-pressure and temperature partitioning of the HSE. Instead, our estimate implies 0.6-0.7% by mass of late accretion of broadly chondritic material to Mars. Our results indicate that Mars could have accreted earlier than Earth, but that disproportional accretion of large bodies and a relative constant flux of accretion of available materials in the first 50-100 Ma of Solar System led to the broad similarity in HSE abundances between Earth and Mars.

The Phase Transformation and Crystal Structure Studies of Strontium Substituted Barium Monoferrite

NASA Astrophysics Data System (ADS)

Mulyawan, A.; Adi, W. A.; Mustofa, S.; Fisli, A.

2017-03-01

Unlike other AFe2O4 ferrite materials, Barium Monoferrite (BaFe2O4) have an orthorhombic structure which is very interesting to further study the crystal structure and phase formation. In this study, Strontium substituted Barium Monoferrite in the form of Ba(1-x)Sr(x)Fe2O4 has successfully been synthesized through solid state reaction method which includes BaCO3, SrCO3, and Fe2O3 as starting materials. Ba(1-x)Sr(x)Fe2O4 was made by varying the dopant composition of Strontium (Sr2+) from x = 0, 0.1, 0.3, and 0.5. Each composition was assisted by ethanol and continued to the milling process for 5 hours then followed by sintering process at 900 °C for 5 hours. The phase transformation was studied by using X-ray diffractometer (XRD) and Rietveld refinement using General Structure Analysis System (GSAS) also 3D crystal visualization using VESTA. Referring to the refinement results, a single phase of BaFe2O4 was formed in x = 0 and 0.1. The composition has orthorhombic structure, space group B b21m, and lattice parameters of a = 19.0229, b = 5.3814 c = 8.4524 Å, α = β = γ = 90° and a = 18.9978, b = 5.3802 c = 8.4385 Å, α = β = γ = 90° respectively. In the composition of x = 0.3 it was found that the phase of BaSrFe4O8 begin to form due to the overload expansion of the Sr2+ occupancy which made the distortion of the initial lattice parameters and finally in the x = 0.5 composition the single phase of BaSrFe4O8 was clearly formed. Energy Dispersive Spectroscopy (EDS) was used to confirm the change of the material structure by measuring the elemental compound composition ratio. The result of EDS spectra clearly exhibited the dominant elements were Barium (Ba), Strontium (Sr), Iron (Fe), and Oxygen (O) with the compound ratio (Atomic percentage and mass percentage) correspond to the BaFe2O4 and BaSrFe4O8 phase.

Luna 16 - Some Li, K, Rb, Sr, Ba, rare-earth, Zr, and Hf concentrations.

NASA Technical Reports Server (NTRS)

Philpotts, J. A.; Schnetzler, C. C.; Schuhmann, S.; Thomas , H. H.; Bottino, M. L.

1972-01-01

Concentrations of Li, K, Rb, Sr, Na, rare-earths, Zr and Hf have been determined for some Luna 16 core materials by mass-spectrometric isotope-dilution. Two regolith fines samples from different depths in the core, and four rock-chips, including both igneous rocks and breccias, have similar trace-element concentrations. The Luna 16 materials have general lunar trace-element characteristics but differ from other returned lunar samples in a manner that suggests the presence of excess feldspar. Unless the Luna 16 igneous rocks are fused soils, they appear to represent either partial plagioclase cumulates or the least differentiated igneous material yet returned from the moon. The similarity in trace-element concentrations of the igneous rocks and the fines would then suggest largely local derivation of the Luna 16 regolith.

Magnified pseudo-elemental map of atomic column obtained by Moiré method in scanning transmission electron microscopy.

PubMed

Kondo, Yukihito; Okunishi, Eiji

2014-10-01

Moiré method in scanning transmission electron microscopy allows observing a magnified two-dimensional atomic column elemental map of a higher pixel resolution with a lower electron dose unlike conventional atomic column mapping. The magnification of the map is determined by the ratio between the pixel size and the lattice spacing. With proper ratios for the x and y directions, we could observe magnified elemental maps, homothetic to the atomic arrangement in the sample of SrTiO3 [0 0 1]. The map showed peaks at all expected oxygen sites in SrTiO3 [0 0 1]. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Strontium isotopes reveal weathering processes in lateritic covers in southern China with implications for paleogeographic reconstructions

PubMed Central

Wei, Xiao; Wang, Shijie; Ji, Hongbing; Shi, Zhenhua

2018-01-01

The isotope ratios of Sr are useful tracers for studying parent material sources, weathering processes, and biogeochemical cycling. Mineralogical and geochemical investigations of two lateritic weathering covers, in an area close to the Tropic of Cancer (Guangxi Province, southern China), were undertaken to study the regional weathering processes and Sr isotopic sources. We found that weathering and decomposition of Rb- and Sr-bearing minerals change the Sr isotopic composition in weathering products (lateritic soils). Weathering of illite lowered the 87Sr/86Sr ratio whereas dissolving and leaching of carbonate minerals increased the 87Sr/86Sr ratio. An Fe nodular horizon is widely developed on the top of the weathering covers in the studied area and it differs from the lateritic soil horizon in mineral composition, construction, and elemental concentration. Furthermore, both Fe2O3 and P2O5 (concentrations) are negatively correlated with the 87Sr/86Sr ratios, suggesting fixation of apatite by Fe oxides is a controlling factor of the Sr isotopic composition in the Fe nodular horizon. The 87Sr/86Sr and Nb/Sr ratios imply the contents and proportions of Fe nodules and clay are critical in controlling the changes of Sr isotopic composition in the Fe nodular horizon. The two stages of the weathering process of carbonate rocks are revealed by the87Sr/86Sr versus Nb/Sr diagram. The 87Sr/86Sr and Rb/Sr ratios suggest that Sr isotopes in the weathering covers within the studied area are derived mainly from parent rock weathering and that the contributions from allothogenic Sr isotopes are limited. A comparison of Sr isotopic composition signatures in the weathering covers of the studied area and Guizhou Province provided insight into the Sr isotopic source and paleogeographic evolution of southern China. From the Permian to the Triassic, the continental fragment sources of the South China sedimentary basin changed significantly. In the Permian, Southern China presented the paleogeographic pattern that the north was higher (in elevation) than the south. PMID:29373592

Strontium isotopes reveal weathering processes in lateritic covers in southern China with implications for paleogeographic reconstructions.

PubMed

Wei, Xiao; Wang, Shijie; Ji, Hongbing; Shi, Zhenhua

2018-01-01

The isotope ratios of Sr are useful tracers for studying parent material sources, weathering processes, and biogeochemical cycling. Mineralogical and geochemical investigations of two lateritic weathering covers, in an area close to the Tropic of Cancer (Guangxi Province, southern China), were undertaken to study the regional weathering processes and Sr isotopic sources. We found that weathering and decomposition of Rb- and Sr-bearing minerals change the Sr isotopic composition in weathering products (lateritic soils). Weathering of illite lowered the 87Sr/86Sr ratio whereas dissolving and leaching of carbonate minerals increased the 87Sr/86Sr ratio. An Fe nodular horizon is widely developed on the top of the weathering covers in the studied area and it differs from the lateritic soil horizon in mineral composition, construction, and elemental concentration. Furthermore, both Fe2O3 and P2O5 (concentrations) are negatively correlated with the 87Sr/86Sr ratios, suggesting fixation of apatite by Fe oxides is a controlling factor of the Sr isotopic composition in the Fe nodular horizon. The 87Sr/86Sr and Nb/Sr ratios imply the contents and proportions of Fe nodules and clay are critical in controlling the changes of Sr isotopic composition in the Fe nodular horizon. The two stages of the weathering process of carbonate rocks are revealed by the87Sr/86Sr versus Nb/Sr diagram. The 87Sr/86Sr and Rb/Sr ratios suggest that Sr isotopes in the weathering covers within the studied area are derived mainly from parent rock weathering and that the contributions from allothogenic Sr isotopes are limited. A comparison of Sr isotopic composition signatures in the weathering covers of the studied area and Guizhou Province provided insight into the Sr isotopic source and paleogeographic evolution of southern China. From the Permian to the Triassic, the continental fragment sources of the South China sedimentary basin changed significantly. In the Permian, Southern China presented the paleogeographic pattern that the north was higher (in elevation) than the south.

Chemical strain-dependent two-dimensional transport at R AlO 3 / SrTiO 3 interfaces ( R = La , Nd , Sm , and Gd )

DOE PAGES

Li, Chen; Shen, Xuan; Yang, Yurong; ...

2016-12-27

Perovskite RAlO 3 (R = La, Nd, Sm, and Gd) films have been deposited epitaxially on (001) TiO 2-terminated SrTiO 3 substrates. In this paper, it is observed that the two-dimensional transport characteristics at the RAlO 3/SrTiO 3 interfaces are very sensitive to the species of rare-earth element, that is to chemical strain. Although electron energy loss spectroscopy measurements show that electron transfer occurs in all the four polar/nonpolar heterostructures, the amount of electrons transferred across SmAlO 3/SrTiO 3 and GdAlO 3/SrTiO 3 interfaces are much less than those across LaAlO 3/SrTiO 3 and NdAlO 3/SrTiO 3 interfaces. First-principles calculationsmore » reveal the competition between ionic polarization and electronic polarization in the polar layers in compensating the build-in polarization due to the polar discontinuity at the interface. Finally, in particular, a large ionic polarization is found in SmAlO 3/SrTiO 3 and GdAlO 3/SrTiO 3 systems (which experience the largest tensile epitaxial strain), hence reducing the amount of electrons transferred.« less

Effect of agriculture on water quality of Lake Biwa tributaries, Japan.

PubMed

Nakano, Takanori; Tayasu, Ichiro; Yamada, Yoshihiro; Hosono, Takahiro; Igeta, Akitake; Hyodo, Fujio; Ando, Atsushi; Saitoh, Yu; Tanaka, Takuya; Wada, Eitaro; Yachi, Shigeo

2008-01-15

We investigated the effects of natural environments and human activity on Lake Biwa, central Japan. We determined the concentrations of 19 elements and the compositions of stable S and Sr isotopes in the main tributaries of the lake and compared them with the corresponding values obtained from the lake water during the circulation period. Results of a principal component analysis indicated that the components dissolved in the lower reaches of the tributaries can be divided into group 1 (HCO(3), SO(4), NO(3), Ca, Mg, Sr) and group 2 components (Cl, Br, Na, K, Ba, Rb, Cs). The concentrations of group 1 components were high in the rivers of the southern area, which is urbanized and densely populated, and the eastern area, which consists of plains where agriculture predominates, compared with the rivers of the northern and western areas, which are mostly mountainous and sparsely populated. The concentrations of group 2 components tended to be high in the river water of industrial areas. The delta(34)S values of SO(4) in the river water converged to 0+/-2 per thousand as the SO(4) concentration increased and, excluding the areas where limestone is extensively distributed, as the HCO(3) concentration increased. In particular, both the delta(34)S values (0+/-2 per thousand) and the (87)Sr/(86)Sr ratios (0.7117+/-0.0005) fell within narrow ranges in the small and medium rivers of the eastern plain area, where rice is widely grown. These values agreed respectively with the delta(34)S values of the fertilizers used in the Lake Biwa basin and the soil-exchangeable (87)Sr/(86)Sr in the eastern plain. The characteristics of water quality in the small and medium rivers of the eastern area can be explained by a model in which sulfuric, nitric, and bicarbonic acids generated by the decomposition of agricultural fertilizer and paddy rice selectively leached out alkaline-earth elements adsorbed on the soil and sediments of the plain or dissolved calcium carbonate enriched with Mg and Sr. Compared with tributary waters, the lake water was depleted in NO(3), owing to denitrification, and in Mn, owing to mineralization, which occur under the redox condition of bottom sediments. Excluding NO(3) and Mn, the compositions of both the dissolved elements and the Sr and S isotopes in the water of Lake Biwa can be approximately reproduced by simple mixing of the tributary water, indicating that these components provide effective indices for evaluating the relationship between the waters of the lake and its tributaries.

Development of the chromatographic partitioning of cesium and strontium utilizing two macroporous silica-based calix[4]arene-crown and amide impregnated polymeric composites: PREC partitioning process.

PubMed

Zhang, Anyun; Kuraoka, Etsushu; Kumagai, Mikio

2007-07-20

To partition effectively Cs(I) and Sr(II), two harmful heat emitting nuclides, from a highly active liquid waste by extraction chromatography, two kinds of macroporous silica-based polymeric materials, Calix[4]arene-R14/SiO(2)-P and TODGA/SiO(2)-P, were synthesized. Two chelating agents, 1,3-[(2,4-diethyl-heptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14), an excellent supramolecular compound having molecular recognition ability for Cs(I), and N,N,N',N'-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) were impregnated and immobilized into the pores of SiO(2)-P particles support by a vacuum sucking technique. The loading and elution of 11 typical simulated fission and non-fission products from 4.0M or 2.0M HNO(3) were performed at 298K. It was found that in the first column packed with the Calix[4]arene-R14/SiO(2)-P, all of the simulated elements were separated effectively into two groups: (1) Na(I), K(I), Sr(II), Fe(III), Ba(II), Ru(III), Pd(II), Zr(IV), and Mo(VI) (noted as Sr-group); (2) Cs(I)-Rb(I) (Cs-group) by eluting with 4.0M HNO(3) and distilled water, respectively. The harmful element Cs(I) flowed into the second group along with Rb(I) because of their close sorption and elution properties towards Calix[4]arene-R14/SiO(2)-P, while Sr(II) showed no sorption and flowed into Sr-containing group. In the second column packed with TODGA/SiO(2)-P, the Sr-group was separated into (1) Ba(II), Ru(III), Na(I), K(I), Fe(III), and Mo(VI) (non-sorption group); (2) Sr(II); (3) Pd(II); and (4) Zr(IV) by eluting with 2.0M HNO(3), 0.01M HNO(3), 0.05M DTPA-pH 2.5, and 0.5M H(2)C(2)O(4), respectively. Sr(II) adsorbed towards TODGA/SiO(2)-P flowed into the second group and showed the excellent separation efficiency from others. Based on the elution behavior of the tested elements, an advanced PREC (Partitioning and Recovery of two heat generators from an acidic HLW (high activity liquid waste) by Extraction Chromatography) process was proposed.

[On the effect of partial flooding on 137Cs and 90Sr in forest biogeocenosis].

PubMed

Perevolotskaia, T V; Bulavik, I M; Perevolotskiĭ, A N

2009-01-01

The analysis was made on 137Cs and 90Sr distribution oak, pine and hornbeam plantations depending on different under soil water levels. Intensity of 137Cs and of 90Sr migration along the vertical layers of soils is determined by under soil water level at a specific sampling site. The closer under soil water to the surface of the soil, the lowest radionuclide contamination is in the upper soil levels and the highest radionuclide contamination is in the deeper layers. The "fast" and "slow" quasi diffusion coefficients for 137Cs and for 90Sr and their contribution to the total migration of radionuclide through vertical soil levels were determined. A decrease in 137Cs and increase in 90Sr transfer factors to the elements of overground phytomass as a result of under soil water level lowering was established.

Preliminary study on multi-element profile mapping of crustal and mantle zircons by using Synchrotron Radiation X-ray Fluorescence (SR-XRF)

NASA Astrophysics Data System (ADS)

Hasözbek, Altug; Shyam, Badri; Siebel, Wolfgang; Schmitt, Axel; Akay, Erhan; Skinner, Lawrie

2013-04-01

Zircon (ZrSiO4) is a mineral of singular importance in the geosciences. Zircon microanalysis has greatly contributed to our understanding of key events in earth's history as certain radioactive heavy elements and their daughter products are well-preserved within the exceptionally stable inorganic matrix of the mineral. A prevailing notion in this field is that zircon, as a mineral, is predominantly a crustal mineral; this has been contested in the last few years with more reports of mantle-derived zircons (Siebel et al., 2009). Zircons enriched from different parts of the upper mantle to lower crust from Turkey (Hasozbek et al. 2010) and Germany (Siebel et al., 2009) will be presented in this study using SR-XRF mapping carried out at beamline 2-IDE at the Advanced Photon Source synchrotron facility (Argonne National Laboratory, USA). The high-resolution (5-10 µm) elemental maps were obtained with collimated and linearly polarized synchrotron radiation (10 to 17 keV) and possess the advantage of being a completely non-destructive technique. Elemental maps of various trace and rare-earth elements along the cross-section of the zircons reveal a zonation-related distribution, which may be used to reveal factors affecting the growth history and dynamics of the crystal formation. Further, abrupt changes in elemental distribution or concentration were found to correspond to faults or inclusions within the zircon crystal. If such observations are found to be applicable for a wide range of samples, elemental mapping with this technique may serve as an important qualitative diagnostic to locating µ-meter inclusions that may be challenging to identify using other techniques (ICP-MS LA, SHRIMP,…) Through these preliminary elemental profile mapping studies of crustal and mantle zircons using SR-XRF methods, we aim to highlight a relatively quick and promising analytical method that may be used to study various geological problems.

Binding of Dissolved Strontium by Micrococcus luteus

PubMed Central

Faison, Brendlyn D.; Cancel, Carmen A.; Lewis, Susan N.; Adler, Howard I.

1990-01-01

Resting cells of Micrococcus luteus have been shown to remove strontium (Sr) from dilute aqueous solutions of SrCl2 at pH 7. Loadings of 25 mg of Sr per g of cell dry weight were achieved by cells exposed to a solution containing 50 ppm (mg/liter) of Sr. Sr binding occurred in the absence of nutrients and did not require metabolic activity. Initial binding was quite rapid (<0.5 h), although a slow, spontaneous release of Sr was observed over time. Sr binding was inhibited in the presence of polyvalent cations but not monovalent cations. Ca and Sr were bound preferentially over all other cations tested. Sr-binding activity was localized on the cell envelope and was sensitive to various chemical and physical pretreatments. Bound Sr was displaced by divalent ions or by H+. Other monovalent ions were less effective. Bound Sr was also removed by various chelating agents. It was concluded that Sr binding by M. luteus is a reversible equilibrium process. Both ion exchange mediated by acidic cell surface components and intracellular uptake may be involved in this activity. PMID:16348370

Regulation of axonal and dendritic growth by the extracellular calcium-sensing receptor (CaSR)

PubMed Central

Vizard, Thomas N.; O'Keeffe, Gerard W.; Gutierrez, Humberto; Kos, Claudine H.; Riccardi, Daniela; Davies, Alun M.

2009-01-01

The extracellular calcium-sensing receptor (CaSR) monitors the systemic extracellular free ionized calcium level ([Ca2+]o) in organs involved in systemic [Ca2+]o homeostasis. However, the CaSR is also expressed in the nervous system where its role is unknown. Here we find high levels of the CaSR in perinatal mouse sympathetic neurons when their axons are innervating and branching extensively in their targets. Manipulating CaSR function in these neurons by varying [Ca2+]o, using CaSR agonists and antagonists or expressing a dominant-negative CaSR markedly affects neurite growth in vitro Sympathetic neurons lacking the CaSR have smaller neurite arbors in vitro, and sympathetic innervation density is reduced in CaSR-deficient mice in vivo. Hippocampal pyramidal neurons, which also express the CaSR, have smaller dendrites when transfected with dominant-negative CaSR in postnatal organotypic cultures. Our findings reveal a crucial role for the CaSR in regulating the growth of neural processes in the peripheral and central nervous systems. PMID:18223649

A preliminary bioavailable strontium isotope soil map of Europe.

NASA Astrophysics Data System (ADS)

Hoogewerff, Jurian; Reimann, Clemens; Ueckermann, Henriette; Frei, Robert; Frei, Karin; van Aswegen, Thalita; Stirling, Claudine; Reid, Malcolm; Clayton, Aaron; Gemas Project Team

2017-04-01

The GEMAS project collected samples from grazing land (n=2118, 0-20cm depth) and agricultural soil (n=2211, 0-10cm depth) at a scale of 1 site/2500km2 in most of Europe1. Elemental analysis using different extractions (Aqua Regia and MMI), whole soil XRF data and Q-ICPMS lead isotope data have been published1. Here we report high-precision 87Sr/86Sr results for the first 1000+ samples. To best represent Sr in plants and animals an ammonium nitrate soil extraction was chosen2. Samples were measured in three laboratories and shared QC samples demonstrated the robustness of the complete extraction and measurement protocol. Observed 87Sr/86Sr values range from 0.7038 to 0.7597 with the majority of samples centring about the median of 0.7092. Spatial interpolation of the data shows some major trends over Europe with high 87Sr/86Sr in known old intrusive terrains in Scandinavia, Iberia and the Alps. To improve the spatial resolution we investigated relations between measured 87Sr/86Sr values and other parameters for which higher spatial density (interpolated) data exists in geological and lithological databases like IGME50003 and GLiM4. For each sampling site matching geological age data and lithology were obtained by overlaying sampling locations on the IGME5000 and GLiM maps and extracting age and lithology information. All statistical and geospatial manipulations were performed using the R statistical package. Overall the 87Sr/86Sr values show a moderate correlation (Pearson R=0.54) with age but demonstrate varying homogeneity in different lithological units. Within the GEMAS dataset the strontium isotope ratios correlate most strongly with the lead isotope results,206Pb/208Pb (R=0.56) indicating a combined age and "crustalinity" effect. Whole soil Rb (XRF) is slightly higher correlated (R=0.26) with 87Sr/86Sr than extracted Rb (AR) at R=0.12 indicating some influence of the long term Rb signal in the soil parent material. Sodium is the highest correlated whole soil (XRF) element (R=0.33), which initially might hint at the influence of seaspray as it is often hypothesized that seaspray is a major source of 87Sr/86Sr variation in coastal regions. To test this hypothesis the distances to the coast in the major north-westerly wind direction in Europe and the shortest distance to any coast were calculated. Neither distance measure provided any significant correlation with 87Sr/86Sr values, indicating that the cause of the Na-Sr correlation is not likely to be seaspray, which would agree with poor correlation with presumably mobile Na in the Aqua Regia extracts. In concordance with observations of other authors5 modeling accuracy is improved by creating separate models for contrasting lithologies; igneous, marine limestones and other types. Igneous parent material provided the most convincing model using parameters like age, Rb/Sr ratio and 206Pb/208Pb. Attempts to model 87Sr/86Sr of soil on marine limestones with the LOWESS version 36 87Sr/86Sr vs. age curve were not convincing although some pattern similarity could be observed. Uranium and sodium content combined with pH are reasonable predictors of 87Sr/86Sr in soils on marine limestone parent material. The 87Sr/86Sr dataset with coordinates and models will be available from the main author after publication later in 2017. Reimann, C., et al., (2014). Geologisches Jahrbuch (Reihe B 102), Schweizerbarth, Hannover. Voerkelius S. et al., (2010). Food Chemistry. 118 (4), pp. 933-940. Asch, K., (2003). Geologisches Jahrbuch, SA 3, Schweizerbarth. Hannover. Hartmann, J., and N. Moosdorf (2012), Geochem. Geophys. Geosyst., 13, Q12004. Bataille, C. P. and G. J. Bowen. 2012. Chemical Geology 304-305:39- 52. J. M. McArthur, et al., Journal of Geology, 2001, volume 109, p. 155-170

Trace elements are associated with urinary 8-hydroxy-2'-deoxyguanosine level: a case study of college students in Guangzhou, China.

PubMed

Lu, Shaoyou; Ren, Lu; Fang, Jianzhang; Ji, Jiajia; Liu, Guihua; Zhang, Jianqing; Zhang, Huimin; Luo, Ruorong; Lin, Kai; Fan, Ruifang

2016-05-01

Many trace heavy elements are carcinogenic and increase the incidence of cancer. However, a comprehensive study of the correlation between multiple trace elements and DNA oxidative damage is still lacking. The aim of this study is to investigate the relationships between the body burden of multiple trace elements and DNA oxidative stress in college students in Guangzhou, China. Seventeen trace elements in urine samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of DNA oxidative stress, was also measured using liquid chromatography tandem mass spectrometer (LC-MS/MS). The concentrations of six essential elements including manganese (Mn), copper (Cu), nickel (Ni), selenium (Se), strontium (Sr), and molybdenum (Mo), and five non-essential elements including arsenic (As), cadmium (Cd), aluminum (Al), stibium (Sb), and thallium (Tl), were found to be significantly correlated with urinary 8-OHdG levels. Moreover, urinary levels of Ni, Se, Mo, As, Sr, and Tl were strongly significantly correlated with 8-OHdG (P < 0.01) concentration. Environmental exposure and dietary intake of these trace elements may play important roles in DNA oxidative damage in the population of Guangzhou, China.

The Crystal Stratigraphy of Ontong Java Plateau Plagioclase Pegacrysts: New Insights into the Evolution of LIP Magmas.

NASA Astrophysics Data System (ADS)

Neal, C. R.; Kinman, W. S.

2003-12-01

The Ontong Java Plateau (OJP) is the world's largest LIP made up of 2 isotopically distinct lava types that comprise the Singgalo and Kwaimbaita formations (Tejada et al., 2002, J.Pet 43:449). Some Kwaimbaita basaltic flows contain plagioclase-rich cumulate xenoliths. As plagioclase is stable over a range of magmatic conditions, microanalysis of this phase allows the evolution of the parent magma(s) to be constrained (cf. Davidson & Tepley, 1997, Science 275:826). This crystal stratigraphy approach has been applied to cm-size plagioclase megacrysts from three basaltic units (5B, 6, and 7) recovered at ODP Leg 192 Site 1183. Core-to-rim trace element variations were quantified by LA-ICP-MS, major elements by EPMA, and compositional backscatter SEM imaging was used to investigate the subtle compositional zoning and textural features within the plagioclases. All 5 OJP megacrysts sampled show little core-to-rim anorthite variation (82 mol % An +/- 5%); An-rich plagioclase crystals are resistant to re-equilibration and are more likely to retain magmatic trace element signatures (Blundy & Wood, 1991, GCA 55:193). The Unit 7 (oldest) plagioclase contains a relatively Sr, Ga, REE, and Ti poor core bounded by a resorption surface and a relatively Sr, Ga, REE, and Ti rich zone suggesting this crystal was exposed to 2 compositionally distinct magmas. The Unit 6 plagioclase contains a relatively Sr, Ga, REE, and Ti poor core with increasing abundances toward the rim, consistent with evolution through fractional crystallization. This megacryst also contains a distinct resorption surface bounded by a core-like Sr, REE, and Ti poor zone. The three Unit 5B plagioclases display core-to-rim Sr and Ba increases with little core-to-rim REE and Ga variations. The uppermost Unit 5B crystal (youngest) exhibits a core-to-rim decrease in Ti, while the lower 2 crystals display the opposite relationship. We suggest the textural and trace element variations seen in OJP plagioclase megacrysts are again evidence of magma mixing. Reconstructed liquids suggest at least two distinct mixing end members: an enriched end member, similar to Singgalo-type lavas, and a depleted end member, similar to Kwaimbaita type lavas. As the Singgalo- and Kwaimbaita-type basalts are isotopically distinct (I(Sr) = 0.7041 and 0.7038, resp.), Sr isotope determinations of the different plagioclase zones through microdrilling is planned for the near future to test this hypothesis. If correct, it suggests that both the Kwaimbaita and Singgalo sources were active at the same time, which is in contrast to the stratigraphy determined by whole-rock compositions.

Explaining the Ba, Y, Sr, and Eu abundance scatter in metal-poor halo stars: constraints to the r-process

NASA Astrophysics Data System (ADS)

Cescutti, G.; Chiappini, C.

2014-05-01

Context. Thanks to the heroic observational campaigns carried out in recent years we now have large samples of metal-poor stars for which measurements of detailed abundances exist. In particular, large samples of stars with metallicities -5 < [Fe/H] <-1 and measured abundances of Sr, Ba, Y, and Eu are now available. These data hold important clues on the nature of the contribution of the first stellar generations to the enrichment of our Galaxy. Aims: We aim to explain the scatter in Sr, Ba, Y, and Eu abundance ratio diagrams unveiled by the metal-poor halo stars. Methods: We computed inhomogeneous chemical evolution models for the Galactic halo assuming different scenarios for the r-process site: the electron-capture (EC) supernovae and the magnetorotationally driven (MRD) supernovae scenarios. We also considered models with and without the contribution of fast-rotating massive stars (spinstars) to an early enrichment by the s-process. A detailed comparison with the now large sample of stars with measured abundances of Sr, Ba, Y, Eu, and Fe is provided (both in terms of scatter plots and number distributions for several abundance ratios). Results: The scatter observed in these abundance ratios of the very metal-poor stars (with [Fe/H] <-2.5) can be explained by combining the s-process production in spinstars, and the r-process contribution coming from massive stars. For the r-process we have developed models for both the EC and the MRD scenarios that match the observations. Conclusions: With the present observational and theoretical constraints we cannot distinguish between the EC and the MRD scenarios in the Galactic halo. Independently of the r-process scenarios adopted, the production of elements by an s-process in spinstars is needed to reproduce the spread in abundances of the light neutron capture elements (Sr and Y) over heavy neutron capture elements (Ba and Eu). We provide a way to test our suggestions by means of the distribution of the Ba isotopic ratios in a [Ba/Fe] or [Sr/Ba] vs. [Fe/H] diagram. Appendix A is available in electronic form at http://www.aanda.org

Evolution of the upper mantle beneath the southern Baikal rift zone: an Sr-Nd isotope study of xenoliths from the Bartoy volcanoes

NASA Astrophysics Data System (ADS)

Ionov, D. A.; Kramm, U.; Stosch, H.-G.

1992-06-01

Anhydrous and amphibole-bearing peridotite xenoliths occur in roughly equal quantitites in the Bartoy volcanic field about 100 km south of the southern tip of Lake Baikal in Siberia (Russia). Whole-rock samples and pure mineral separates from nine xenoliths have been analyzed for Sr and Nd isotopes in order to characterize the upper mantle beneath the southern Baikal rift zone. In an Sr-Nd isotope diagram both dry and hydrous xenoliths from Bartoy plot at the junction between the fields of MORB and ocean island basalts. This contrasts with data available on two other localities around Lake Baikal (Tariat and Vitim) where peridotites typically have Sr-Nd isotope compositions indicative of strong long-term depletion in incompatible elements. Our data indicate significant chemical and isotopic heterogeneity in the mantle beneath Bartoy that may be attributed to its position close to an ancient suture zone separating the Siberian Platform from the Mongol-Okhotsk mobile belt and occupied now by the Baikal rift. Two peridotites have clinopyroxenes depleted in light rare earth elements (LREE) with Sr and Nd model ages of about 2 Ga and seem to retain the trace element and isotopic signatures of old depleted lithospheric mantle, while all other xenoliths show different degrees of LREE-enrichment. Amphiboles and clinopyroxenes in the hydrous peridotites are in Sr-Nd isotopic disequilibrium. If this reflects in situ decay of 147Sm and 87Rb rather than heterogeneities produced by recent metasomatic formation of amphiboles then 300 400 Ma have passed since the minerals were last in equilibrium. This age range then indicates an old enrichment episode or repeated events during the Paleozoic in the lithospheric mantle initially depleted maybe ˜2 Ga ago. The Bartoy hydrous and enriched dry peridotites, therefore, are unlikely to represent fragments of a young asthenospheric bulge which, according to seismic reflection studies, reached the Moho at the axis of the Baikal rift zone a few Ma ago. By contrast, hydrous veins in peridotites may be associated with rift formation processes.

Trace elements and isotope data of the Um Garayat gold deposit, Wadi Allaqi district, Egypt

NASA Astrophysics Data System (ADS)

Zoheir, Basem; Emam, Ashraf; Pitcairn, Iain K.; Boskabadi, Arman; Lehaye, Yann; Cooper, Matthew J.

2018-04-01

Trace element composition of sulfides and O, C, Sr and S isotopic data are assessed to constrain the evolution and potential fluid and metal sources of the Um Garayat gold deposit. Ore microscopy and BSE investigations of quartz veins show blocky arsenopyrite and pyrite replaced in part by pyrrhotite, chalcopyrite, sphalerite, galena, and gersdorffite. Free-milling gold occurs commonly in close association with the late sulfides, and along fractures in pyrite. On the other hand, recrystallized pyrite is disseminated in host metavolcaniclastic/metasedimentary rocks that commonly contain carbonaceous material. In situ LA-ICP-MS analysis of sulfides shows the recrystallized pyrite enriched in most trace elements, while blocky pyrite contains only some traces of arsenic. Detected concentrations of gold (up to 17 ppm) were only reported in arsenopyrite disseminated in quartz veins. The δ34S values of blocky pyrite and pyrrhotite in quartz veins define a narrow range (1.6 to 3.7‰), suggesting a homogenous sulfur source which is consistent with the dominantly mafic host rocks. The recrystallized pyrite has a distinctive sulfur isotope composition (δ34S - 9.3 to - 10.6‰), which is rather comparable to diagenetic sulfides. Hydrothermal carbonate in quartz veins and wallrock have nearly constant values of δ18O (10.5 to 11.9‰) and δ13C (- 4.2 to - 5.5‰). Based on constraints from mineral assemblages and chlorite thermometry, data of six samples indicate that carbonate precipitation occurred at 280 °C from a homogenous hydrothermal fluid with δ18OH2O 4.4 ± 0.7‰ and δ13C = 3.7 ± 0.8‰. Strontium isotope values of two samples (87Sr/86Sr = 0.7024 and 0.7025) are similar to the initial 87Sr/86Sr ratios of island arc metabasalts ( 710 Ma) in the South Eastern Desert. The generally homogenous sulfur, C, O, Sr isotope data are suggestive of metamorphogenic fluids, likely produced from dominantly mafic volcanic rocks at the greenschist-amphibolite facies transition.

Nanoscale spatial analysis of clay minerals containing cesium by synchrotron radiation photoemission electron microscopy

NASA Astrophysics Data System (ADS)

Yoshigoe, Akitaka; Shiwaku, Hideaki; Kobayashi, Toru; Shimoyama, Iwao; Matsumura, Daiju; Tsuji, Takuya; Nishihata, Yasuo; Kogure, Toshihiro; Ohkochi, Takuo; Yasui, Akira; Yaita, Tsuyoshi

2018-01-01

A synchrotron radiation photoemission electron microscope (SR-PEEM) was applied to demonstrate the pinpoint analysis of micrometer-sized weathered biotite clay particles with artificially adsorbed cesium (Cs) atoms. Despite the insulating properties of the clay, we observed the spatial distributions of constituent elements (Si, Al, Cs, Mg, and Fe) without charging issues and clarified reciprocal site-correlations among these elements with nanometer resolution. We found that Cs atoms were likely to be adsorbed evenly over the entire particle; however, we identified an occupational conflict between Cs and Mg atoms, implying that Cs sorption involves ion exchange processes. Spatially resolved X-ray absorption spectra (XAS) of the Cs4,5 M-edge region showed Cs to be present in a monocation state (Cs+) as typically observed for Cs compounds. Further pinpoint XAS measurements were also performed at the Fe L2,3-edge to determine the chemical valence of the Fe atoms. The shapes of the spectra were similar to those for Fe2O3, indicating that Fe in the clay was in a 3+ oxidation state. From these observations, we infer that charge compensation facilitates Cs adsorption in the vicinity of a substitution site where Si4+ ions are replaced by Fe3+ ions in SiO4 tetrahedral sheets. Our results demonstrate the utility of SR-PEEM as a tool for spatially resolved chemical analyses of various environmental substances, which is not limited by the poor conductivity of samples.

Radionuclide bioconcentration factors and sediment partition coefficients in Arctic Seas subject to contamination from dumped nuclear wastes

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

Fisher, N.S.; Fowler, S.W.; Boisson, F.

1999-06-15

The disposal of large quantities of radioactive wastes in Arctic Seas by the former Soviet Union has prompted interest in the behavior of long-lived radionuclides in polar waters. Previous studies on the interactions of radionuclides prominent in radioactive wastes have focused on temperate waters; the extent to which the bioconcentration factors and sediment partitioning from these earlier studies could be applied to risk assessment analyses involving high latitude systems is unknown. Here the authors present concentrations in seawater and calculated in situ bioconcentration factors for [sup 90]Sr, [sup 137]Cs, and [sup 239+240]Pu (the three most important radionuclides in Arctic riskmore » assessment models) in macroalgae, crustaceans, bivalve molluscs, sea birds, and marine mammals as well as sediment K[sub d] values for 13 radionuclides and other elements in samples taken from the Kara and Barents Seas. The data analysis shows that, typically, values for polar and temperate waters are comparable, but exceptions include 10-fold higher concentration factors for [sup 239+240]Pu in Arctic brown macroalgae, 10-fold lower K[sub d] values for [sup 90]Sr in Kara Sea sediment than in typical temperate coastal sediment, and 100-fold greater Ru K[sub d] values in Kara Sea sediment. For most elements application of temperate water bioconcentration factors and K[sub d] values to Arctic marine systems appears to be valid.« less

Asthenospheric and lithospheric sources for Mesozoic dolerites from Liberia (Africa): trace element and isotopic evidence

NASA Astrophysics Data System (ADS)

Dupuy, C.; Marsh, J.; Dostal, J.; Michard, A.; Testa, S.

1988-01-01

Combined elemental, and Sr and Nd isotopic data are presented for Mesozoic dolerite dikes of Liberia (Africa) which are related to the initial stage of opening of the Atlantic Ocean. The large scatter of both trace element and isotopic data allows the identification of five groups of dolerites which cannot be related to each other by simple processes of mineral fractionation from a common source. On the contrary, the observed chemical and isotopic variation within some dolerites (Groups I and II) may result either from variable degrees of melting of an isotopically heterogeneous source or mixing between enriched and depleted oceanic type mantle. For the other dolerites (Groups III-V) mixing with a third mantle source with more radiogenic Sr and with element ratios characteristic of subduction environments is suggested. This third source is probably the subcontinental lithospheric mantle. Finally, no significant modification by interaction with continental crust is apparent in most of the analyzed samples.

Trace Elements in Water, Sediments and the Elongate Tigerfish Hydrocynus forskahlii (Cuvier 1819) from Lake Turkana, Kenya Including a Comprehensive Health Risk Analysis.

PubMed

Otachi, Elick O; Plessl, Christof; Körner, Wilfried; Avenant-Oldewage, Annemariè; Jirsa, Franz

2015-09-01

This study presents the distribution of 17 major and trace elements in surface water, sediments and fish tissues from Lake Turkana, Kenya. Eight sediment and ten water samples from the west bank of the lake, as well as 34 specimens of the elongate tigerfish Hydrocynus forskahlii caught in that region were examined. It is the first report for Li, Rb, Sr, Mo from the lake and the first report on most of the trace elements for this fish species. The concentrations of elements in the water and sediments showed no sign of pollution. In fish muscle, Li, Zn and Cd showed relatively high abundances, with mean concentrations of 206, 427 and 0.56 mg/kg dw, respectively. The calculated target hazard quotient values for Li, Zn, Sr and Cd were 138.7, 1.9, 4.1 and 0.76, respectively; therefore the consumption of these fish poses a health risk to humans in the area.

Simplified multi-element analysis of ground and instant coffees by ICP-OES and FAAS.

PubMed

Szymczycha-Madeja, Anna; Welna, Maja; Pohl, Pawel

2015-01-01

A simplified alternative to the wet digestion sample preparation procedure for roasted ground and instant coffees has been developed and validated for the determination of different elements by inductively coupled plasma optical emission spectrometry (ICP-OES) (Al, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, Zn) and flame atomic absorption spectrometry (FAAS) (Ca, Fe, K, Mg, Na). The proposed procedure, i.e. the ultrasound-assisted solubilisation in aqua regia, is quite fast and simple, requires minimal use of reagents, and demonstrated good analytical performance, i.e. accuracy from -4.7% to 1.9%, precision within 0.5-8.6% and recovery in the range 93.5-103%. Detection limits of elements were from 0.086 ng ml(-1) (Sr) to 40 ng ml(-1) (Fe). A preliminary classification of 18 samples of ground and instant coffees was successfully made based on concentrations of selected elements and using principal component analysis and hierarchic cluster analysis.

Geological-hydrogeochemical characteristics of a “silver spring” water source (the Lozovy ridge)

NASA Astrophysics Data System (ADS)

Ivanova, I. S.; Bragin, I. V.; Chelnokov, G. A.; Bushkareva, K. Yu; Shvagrukova, E. V.

2016-03-01

Geological and hydrogeological characteristics of the Lozovy ridge (Southern Primorye) are studied, as far as karst phenomena are widely distributed within its boundaries. Water-bearing rocks of the karst water source “Silver Spring” (“Serebryany Klyuch”), which is located near the bottom of the “Bear’s fang” (“Medvezhiy klyk”) cave, are investigated. It is found that karst rocks are presented by calcite (CaCO3), and an accessory mineral is barite (BaSO4). It is determined that among the trace elements forming the composition of carbonate water-bearing rocks the maximum concentrations are typical for Sr, Ba, Fe, Al, Za, Mn, Cu, and Ni. Also, the chemical composition of the waters taken from the “Silver Spring” water source is studied. These waters are fresh, hydrocarbonate, calcium, and weakly alkaline. Among the elements of the spring, such elements as Sr, Ba, Fe, Al, Zn, Mn, Cu, and Ni have the maximum concentration. The other elements have concentrations less than 1 µg/l.

Elemental concentration analysis in prostate tissues using total reflection X-ray fluorescence

NASA Astrophysics Data System (ADS)

Leitão, R. G.; Palumbo, A.; Souza, P. A. V. R.; Pereira, G. R.; Canellas, C. G. L.; Anjos, M. J.; Nasciutti, L. E.; Lopes, R. T.

2014-02-01

Prostate cancer (PCa) currently represents the second most prevalent malignant neoplasia in men, representing 21% of all cancer cases. Benign Prostate Hyperplasia (BPH) is an illness prevailing in men above the age of 50, close to 90% after the age of 80. The prostate presents a high zinc concentration, about 10-fold higher than any other body tissue. In this work, samples of human prostate tissues with cancer, BPH and normal tissue were analyzed utilizing total reflection X-ray fluorescence spectroscopy using synchrotron radiation technique (SR-TXRF) to investigate the differences in the elemental concentrations in these tissues. SR-TXRF analyses were performed at the X-ray fluorescence beamline at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo. It was possible to determine the concentrations of the following elements: P, S, K, Ca, Fe, Cu, Zn and Rb. By using Mann-Whitney U test it was observed that almost all elements presented concentrations with significant differences (α=0.05) between the groups studied.

Application of thermodynamics to silicate crystalline solutions

NASA Technical Reports Server (NTRS)

Saxena, S. K.

1972-01-01

A review of thermodynamic relations is presented, describing Guggenheim's regular solution models, the simple mixture, the zeroth approximation, and the quasi-chemical model. The possibilities of retrieving useful thermodynamic quantities from phase equilibrium studies are discussed. Such quantities include the activity-composition relations and the free energy of mixing in crystalline solutions. Theory and results of the study of partitioning of elements in coexisting minerals are briefly reviewed. A thermodynamic study of the intercrystalline and intracrystalline ion exchange relations gives useful information on the thermodynamic behavior of the crystalline solutions involved. Such information is necessary for the solution of most petrogenic problems and for geothermometry. Thermodynamic quantities for tungstates (CaWO4-SrWO4) are calculated.

Erosion of fluorinated diamond-like carbon films by exposure to soft X-rays

NASA Astrophysics Data System (ADS)

Kanda, Kazuhiro; Takamatsu, Hiroki; Miura-Fujiwara, Eri; Akasaka, Hiroki; Saiga, Akihiro; Tamada, Koji

2018-04-01

The effects of soft X-ray irradiation on fluorinated diamond-like carbon (F-DLC) films were investigated using synchrotron radiation (SR). The Vickers hardness of the F-DLC films substantially increased from an initial value of about 290 to about 800 HV at a dose of 50 mA·h and the remained constant at about 1100 HV at doses of more than 300 mA·h. This dose dependence was consistent with those of the film thickness and elemental composition. The depth profile of the elemental composition inside each F-DLC film obtained by the measurement of the X-ray photoelectron spectrum (XPS) during sputtering showed that the composition ratio of fluorine was approximately constant from the surface to the neighborhood of the substrate. Namely, fluorine atoms were desorbed by SR irradiation from not only the surface but also the substrate neighborhood. Modification by SR irradiation was found to occur in the entire F-DLC film of about 200 nm thickness.

Epitaxial Ferroelectric Ba(0.5)Sr(0.5)TiO3 Thin Films for Room-Temperature High-Frequency Tunable Element Applications

NASA Technical Reports Server (NTRS)

Chen, C. L.; Feng, H. H.; Zhang, Z.; Brazdeikis, A.; Miranda, F. A.; VanKeuls, F. W.; Romanofsky, R. R.; Huang, Z. J.; Liou, Y.; Chu, W. K.;

Age determinations and growth rates of Pacific ferromanganese deposits using strontium isotopes

USGS Publications Warehouse

Ingram, B.L.; Hein, J.R.; Farmer, G.L.

1990-01-01

87Sr 86Sr ratios, trace element and REE compositions, and textural characteristics were determined for three hydrogenetic Fe-Mn crusts, one hydrothermal deposit, and two mixed hydrothermalhydrogenetic crusts from the Pacific. The Sr isotope data are compared to the Sr seawater curve for the Cenozoic to determine the ages and growth rates of the crusts. The 87Sr 86Sr in the crusts does not increase monotonically with depth as expected if the Sr were solely derived from seawater and perfectly preserved since deposition. This indicates post-depositional exchange of Sr or heterogeneous sources for the Sr originally contained in the crusts. Textures of hydrogenetic crusts generally correlate with Sr isotopic variations. The highest porosity intervals commonly exhibit the highest 87Sr 86Sr ratios, indicating exchange with younger seawater. Intervals with the lowest porosity commonly have lower 87Sr 86Sr and may preserve the original Sr isotopic ratios. Minimum ages of crust growth inception were calculated from dense, low porosity intervals. Growth of the hydrogenetic crusts began at or after 23 Ma, although their substrates are Cretaceous. Estimated average growth rates of the three hydrogenetic crusts vary between 0.9 and 2.7 mm/Ma, consistent with published rates determined by other techniques. Within the Marshall Islands crust, growth rates for individual layers varied greatly between 1.0 and 5.4 mm/Ma. For one crust, very low 87Sr 86Sr ratios occurred in detrital-rich intervals. Hydrothermal Fe-Mn oxide from the active Lau Basin back-arc spreading axis (Valu Fa Ridge) has an 87Sr 86Sr ratio with a predominantly seawater signature ( 87Sr 86Sr 0.709196), indicating a maximum age of 0.9 Ma. One crust from an off-axis seamount west of Gorda Ridge may have begun precipitating hydrogenetically at 0.5 Ma (0.709211), and had increasing hydrothermal or volcanic input in the top half of the crust, indicated by a significantly lower 87Sr 86Sr ratio (0.709052). ?? 1990.

Evidence for mass-dependent isotopic fractionation of strontium in a glaciated granitic watershed

NASA Astrophysics Data System (ADS)

de Souza, Gregory F.; Reynolds, Ben C.; Kiczka, Mirjam; Bourdon, Bernard

2010-05-01

The stable isotope composition of strontium (expressed as δ 88/86Sr) may provide important constraints on the global exogenic strontium cycle. Here, we present δ 88/86Sr values and 87Sr/ 86Sr ratios for granitoid rocks, a 150 yr soil chronosequence formed from these rocks, surface waters and plants in a small glaciated watershed in the central Swiss Alps. Incipient chemical weathering in this young system, whether of inorganic or biological origin, has no resolvable effect on the 87Sr/ 86Sr ratios and δ 88/86Sr values of bulk soils, which remain indistinguishable from bedrock in terms of Sr isotopic composition. Although due in part to the chemical heterogeneity of the forefield, the lack of a resolvable difference between soil and bedrock isotopic composition indicates that these soils have thus far witnessed minimal net loss of Sr; a low degree of chemical weathering is also implied by bulk soil chemistry. The isotopic composition of Sr in streamwater is more radiogenic than median soil, reflecting the preferential weathering of biotite in the catchment; streamwater δ 88/86Sr values, however, are indistinguishable from bulk soil δ 88/86Sr values, implying that no resolvable fractionation of Sr isotopes takes place during release to the weathering flux in the Damma forefield. Analyses of plant tissue reveal that plants ( Rhododendron and Vaccinium) preferentially assimilate the lighter isotopes of Sr such that their δ 88/86Sr values are significantly lower than those of the soils in which they grow. Additionally, δ 88/86Sr values of foliar and floral tissues are lower than those of roots, contrary to observations for Ca, for which Sr is often used as an analogue in weathering studies. We suggest that processes that discriminate against Sr in favour of Ca, due to the different nutritional requirement of plants for these two elements, are responsible for the observed contrast.

Zircon U-Pb geochronology, Sr-Nd-Hf isotopic composition and geological significance of the Late Triassic Baijiazhuang and Lvjing granitic plutons in West Qinling Orogen

NASA Astrophysics Data System (ADS)

Duan, Meng; Niu, Yaoling; Kong, Juanjuan; Sun, Pu; Hu, Yan; Zhang, Yu; Chen, Shuo; Li, Jiyong

2016-09-01

The Qinling Orogen was a consequence of continental collision of the South China Craton with the North China Craton in the Triassic and caused widespread granitoid magmatism. However, the petrogenesis of these granitoids remains controversial. In this paper, we choose the Baijiazhuang (BJZ) and Lvjing (LJ) plutons in the West Qinling Orogen for a combined study of the zircon U-Pb geochronology, whole-rock major and trace element compositions and Sr-Nd-Hf isotopic characteristics. We obtained zircon crystallization ages of 216 Ma and 212 Ma for the BJZ and the LJ plutons, respectively. The granitoid samples from both plutons have high K2O metaluminous to peraluminous compositions. They are enriched in large ion lithophile elements (LILEs), light rare earth elements (LREEs) and depleted in high field-strength elements (HFSEs) with significant negative Eu anomalies. The BJZ samples have initial Sr isotopic ratios of 0.7032 to 0.7078, εNd(t) of - 10.99 to - 8.54 and εHf (t) of - 10.22 to - 6.41. The LJ granitoids have initial Sr isotopic ratios of 0.7070 to 0.7080, εNd(t) of - 5.37 to - 4.58 and εHf(t) of - 3.64 to - 1.78. The enriched isotopic characteristics of the two plutons are consistent with their source being dominated by ancient continental crust. However, two BJZ samples show depleted Sr isotope compositions, which may infer possible involvement of mantle materials. Mantle-derived melt, which formed from partial melting of mantle wedge peridotite facilitated by dehydration of the subducted/subducting Mianlue ocean crust, provide the required heat for the crustal melting while also contributing to the compositions of these granitoids. That is, the two granitic plutons are magmatic responses to the closure of the Mianlue ocean basin and the continental collision between the Yangtze and South Qinling crustal terranes. (143Nd/144Nd)i = (143Nd/144Nd) - (147Sm/144Nd) × (eλt - 1), εNd(t) = [(143Nd/144Nd) / (143Nd/144Nd)CHUR(t) - 1] × 104, (143Nd/144Nd)CHUR(t) = 0.512638-0.1967 × (eλt - 1), TDM = 1/λ × ln{1 + [((143Nd/144Nd) - 0.51315) / ((147Sm/144Nd) - 0.21317)]}, λ Sm-Nd = 6.54 × 10- 12a- 1. (176Hf/177Hf)i = [(176Hf/177Hf) - (176Lu/177Hf) × (eλt - 1), εHf(t) = [(176Hf/177Hf) / (176Hf/177Hf)CHUR(t) - 1] × 104, TDM1 = 1/λ × ln[1 + ((176Hf/177Hf)Sample - (176Hf/177Hf)DM)/((176Lu/177Hf)Sample - (176Lu/177Hf)DM)], TDM2 = TDM1 - (TDM1 - t)((fCC - fSample) / (fCC - fDM)), fLu-Hf = (176Lu/177Hf)Sample / (176Lu/177Hf)CHUR-1, (176Lu/177Hf)CHUR = 0.0332, (176Hf/177Hf)CHUR, 0 = 0.282785, (176Lu/177Hf)DM = 0.0384, (176Hf/177Hf)DM = 0.28325, fCC, fSample, fDM are their own fLu-Hf, λ = 1.867 × 10- 11a- 1.

Development of continental lithospheric mantle as reflected in the chemistry of the Mesozoic Appalachian Tholeiites, U.S.A.

NASA Astrophysics Data System (ADS)

Pegram, William J.

1990-03-01

Geochemical analyses of dikes, sills, and volcanic rocks of the Mesozoic Appalachian Tholeiite (MAT) Province of the easternmost United States provide evidence that continental tholeiites are derived from continental lithospheric mantle sources that are genetically and geochronologically related to the overlying continental crust. Nineteen olivine tholeiites and sixteen quartz tholeiites from the length of this province, associated in space and time with the last opening of the Atlantic, display significant isotopic heterogeneity: initial ɛ Nd = +3.8 to -5.7; initial 87Sr/ 86Sr= 0.7044-0.7072; 206Pb/ 204Pb= 17.49-19.14; 207Pb/ 204Pb= 15.55-15.65; 208Pb/ 204Pb= 37.24-39.11. In Pb sbnd Pb space, the MAT define a linear array displaced above the field for MORB and thus resemble oceanic basalts with DUPAL Pb isotopic traits. A regression of this array yields a secondary Pb sbnd Pb isochron age of ≈ 1000 Ma (μ 1 = 8.26), similar to Sm/Nd isochrons from the southern half of the province and to the radiometric age of the Grenville crust underlying easternmost North America. The MAT exhibit significant trace element ratio heterogeneity (e.g., Sm/Nd= 0.226-0.327) and have trace element traits similar to convergent margin magmas [e.g., depletions of Nb and Ti relative to the rare earth elements on normalized trace element incompatibility diagrams, Ba/Nb ratios (19-75) that are significantly greater than those of MORB, and low TiO 2 (0.39-0.69%)]. Geochemical and geological considerations very strongly suggest that the MAT were not significantly contaminated during ascent through the continental crust. Further, isotope and trace element variations are not consistent with the involvement of contemporaneous MORB or OIB components. Rather, the materials that control the MAT incompatible element chemistry were derived from subcontinental lithospheric mantle. Thus: (1) the MAT/arc magma trace element similarities; (2) the Pb sbnd Pb and Sm/Nd isochron ages; and (3) the need for a method of introducing an ancient (> 2-3 Ga) Pb component into subcontinental mantle that cannot be much older than 1 Ga leads to a model whereby the MAT were generated by the melting of sediment-contaminated arc mantle that was incorporated into the continental lithosphere during arc activity preceding the Grenville Orogeny (≈ 1000 Ma).

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

Identification of gene expression profiling associated with erlotinib-related skin toxicity in pancreatic adenocarcinoma patients

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

Caba, Octavio, E-mail: ocaba@ujaen.es

Erlotinib is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that showed activity against pancreatic ductal adenocarcinoma (PDAC). The drug's most frequently reported side effect as a result of EGFR inhibition is skin rash (SR), a symptom which has been associated with a better therapeutic response to the drug. Gene expression profiling can be used as a tool to predict which patients will develop this important cutaneous manifestation. The aim of the present study was to identify which genes may influence the appearance of SR in PDAC patients. The study included 34 PDAC patients treated with erlotinib: 21 patientsmore » developed any grade of SR, while 13 patients did not (controls). Before administering any chemotherapy regimen and the development of SR, we collected RNA from peripheral blood samples of all patients and studied the differential gene expression pattern using the Illumina microarray platform HumanHT-12 v4 Expression BeadChip. Seven genes (FAM46C, IFITM3, GMPR, DENND6B, SELENBP1, NOL10, and SIAH2), involved in different pathways including regulatory, migratory, and signalling processes, were downregulated in PDAC patients with SR. Our results suggest the existence of a gene expression profiling significantly correlated with erlotinib-induced SR in PDAC that could be used as prognostic indicator in this patients. - Highlights: • Skin rash (SR) is the most characteristic side effect of erlotinib in PDAC patients. • Erlotinib-induced SR has been associated with a better clinical outcome. • Gene expression profiling was used to determine who will develop this manifestation. • 7 genes involved in different pathways were downregulated in PDAC patients with SR. • Our profile correlated with erlotinib-induced SR in PDAC could be used for prognosis.« less

Trace elements levels in the serum, urine, and semen of patients with infertility.

PubMed

Sağlam, Hasan Salih; Altundağ, Hüseyin; Atik, Yavuz Tarık; Dündar, Mustafa Şahin; Adsan, Öztug

2015-01-01

Studies suggest that trace elements may have an adverse impact on male reproduction, even at low levels. We tried to investigate the relationships between these metals and semen quality in various body fluids among men with infertility. A total of 255 samples of blood, semen, and urine were collected from 85 men suffering from infertility. Inductively coupled plasma-optical emission spectrometry was used for the determination of 22 trace elements. We compared the results of the semen parameters with the results of the element determinations. Because of the high proportion of samples with values lower than the limit of detection for a number of the elements, only 8 of a total 22 trace elements were determined in the samples. When the concentrations of sperm were classified according to the World Health Organization's guidelines for normospermia, oligospermia, and azoospermia, statistically significant differences were found among Zn, Ca, Al, Cu, Mg, Se, and Sr concentrations in various serum, sperm, and urine samples (P < 0.05). In the present study, we found significant correlations between concentrations of Zn, Ca, Al, Cu, Mg, Se, and Sr and semen parameters in various body fluids.

Materials and methods for the separation of oxygen from air

DOEpatents

MacKay, Richard; Schwartz, Michael; Sammells, Anthony F.

2003-07-15

Metal oxides particularly useful for the manufacture of catalytic membranes for gas-phase oxygen separation processes having the formula: O.sub.5+z where: x and x' are greater than 0; y and y' are greater than 0; x+x' is equal to 2; y+y' is less than or equal to 2; z is a number that makes the metal oxide charge neutral; A is an element selected from the lanthanide elements; A' is an element selected from Be, Mg, Ca, Sr, Ba and Ra; A" is an element selected from the f block lanthanides, Be, Mg, Ca, Sr, Ba and Ra; B is an element selected from the group consisting of Al, Ga, In or mixtures thereof and B" is Co or Mg, with the exception that when B" is Mg, A' and A" are not Mg. The metal oxides are useful for preparation of dense membranes which may be formed from dense thin films of the mixed metal oxide on a porous metal oxide element. The invention also provides methods and catalytic reactors for oxygen separation and oxygen enrichment of oxygen deficient gases which employ mixed conducting metal oxides of the above formula.

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

NASA Technical Reports Server (NTRS)

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

1974-01-01

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

The HDL receptor SR-BI is associated with human prostate cancer progression and plays a possible role in establishing androgen independence.

PubMed

Schörghofer, David; Kinslechner, Katharina; Preitschopf, Andrea; Schütz, Birgit; Röhrl, Clemens; Hengstschläger, Markus; Stangl, Herbert; Mikula, Mario

2015-08-07

Human prostate cancer represents one of the most frequently diagnosed cancers in men worldwide. Currently, diagnostic methods are insufficient to identify patients at risk for aggressive prostate cancer, which is essential for early treatment. Recent data indicate that elevated cholesterol levels in the plasma are a prerequisite for the progression of prostate cancer. Here, we analyzed clinical prostate cancer samples for the expression of receptors involved in cellular cholesterol uptake. We screened mRNA microarray files of prostate cancer samples for alterations in the expression levels of cholesterol transporters. Furthermore, we performed immunohistochemistry analysis on human primary prostate cancer tissue sections derived from patients to investigate the correlation of SR-BI with clinicopathological parameters and the mTOR target pS6. In contrast to LDLR, we identified SR-BI mRNA and protein expression to be induced in high Gleason grade primary prostate cancers. Histologic analysis of prostate biopsies revealed that 53.6 % of all cancer samples and none of the non-cancer samples showed high SR-BI staining intensity. The disease-free survival time was reduced (P = 0.02) in patients expressing high intra-tumor levels of SR-BI. SR-BI mRNA correlated with HSD17B1 and HSD3B1 and SR-BI protein staining showed correlation with active ribosomal protein S6 (RS = 0.828, P < 0.00001). We identified SR-BI to indicate human prostate cancer formation, suggesting that increased levels of SR-BI may be involved in the generation of a castration-resistant phenotype.

Migration of sharks into freshwater systems during the Miocene and implications for Alpine paleoelevation

NASA Astrophysics Data System (ADS)

Kocsis, László; Vennemann, Torsten W.; Fontignie, Denis

2007-05-01

Trace-element and isotopic compositions of fossilized shark teeth sampled from Miocene marine sediments of the north Alpine Molasse Basin, the Vienna Basin, and the Pannonian Basin generally show evidence of formation in a marine environment under conditions geochemically equivalent to the open ocean. In contrast, two of eight shark teeth from the Swiss Upper Marine Molasse locality of La Molière have extremely low δ18O values (10.3‰ and 11.3‰) and low 87Sr/86Sr ratios (0.707840 and 0.707812) compared to other teeth from this locality (21.1‰ 22.4‰ and 0.708421 0.708630). The rare earth element (REE) abundances and patterns from La Molière not only differ between dentine and enameloid of the same tooth, but also between different teeth, supporting variable conditions of diagenesis at this site. However, the REE patterns of enameloid from the “exotic” teeth analyzed for O and Sr isotopic compositions are similar to those of teeth that have O and Sr isotopic compositions typical of a marine setting at this site. Collectively, this suggests that the two “exotic” teeth were formed while the sharks frequented a freshwater environment with very low 18O-content and Sr isotopic composition controlled by Mesozoic calcareous rocks. This is consistent with a paleogeography of high-elevation (˜2300 m) Miocene Alps adjacent to a marginal sea.

Rb-Sr, Sm-Nd, K-Ca, O, and H isotopic study of Cretaceous-Tertiary boundary sediments, Caravaca, Spain: evidence for an oceanic impact site

USGS Publications Warehouse

DePaolo, D.J.; Kyte, F.T.; Marshall, B.D.; O'Neil, J.R.; Smit, J.

1983-01-01

Isotopic ratios and trace element abundances were measured on samples of Ir-enriched clay at the Cretaceous-Tertiary boundary, and in carbonate and marl from 5 cm below and 3 cm above the boundary. Samples were leached with acetic acid to remove carbonate, and with hydrochloric acid. Leachates and residues were measured. The Sr, Nd, O and H isotopic compositions of the boundary clay residues are distinct from those of the stratigraphically neighboring materials. The data indicate that most of the clay material was derived from a terrestrial source with relatively low 87Sr/86Sr and high 143Nd/144Nd ratios. The ??18O data suggest that the detritus has been modified by submarine weathering. K-Ca and Rb-Sr systematics, as well as O isotope ratios of K-feldspar spherules within the boundary clay, suggest that they are predominantly authigenic and may have formed after the time of deposition. However, Sm-Nd and Rb-Sr isotopic data indicate that the spherules contain relict material that provides information on the nature of the original detritus. The isotopic evidence for foreign terrestrial detritus in the boundary clay, the low rare earth element concentrations and high Ni concentration, support the hypothesis of a terminal Cretaceous asteroidal impact that produced a global layer of fallout. The data are most easily explained if the impact site was on oceanic crust rather than continental crust, and if a substantial fraction of the fallout was derived from relatively deep within the lithosphere (>3 km). This would probably require a single large impactor. ?? 1983.

Mg and Sr in Arctic echinoderm calcite: Nature or nurture?

NASA Astrophysics Data System (ADS)

Iglikowska, A.; Borszcz, T.; Drewnik, A.; Grabowska, M.; Humphreys-Williams, E.; Kędra, M.; Krzemińska, M.; Piwoni-Piórewicz, A.; Kukliński, P.

2018-04-01

The Mg/Ca and Sr/Ca ratios in echinoderm skeletal calcite are used as a proxy for Phanerozoic seawater changes, since the skeletal concentrations are, to some extent, controlled by environmental factors. However, it remains unclear how the influence of environmental factors is modified by vital effects, especially in polar waters. Therefore, the goal of this study was to compare the ratios of Mg/Ca and Sr/Ca among the skeletal parts of 10 common Arctic echinoderm species belonging to three classes Echinoidea, Asteroidea and Ophiuroidea that contribute substantially to the carbon cycle in the Arctic benthic system. Significant differences were recorded in echinoid skeletal element concentrations among specific skeletal parts. The lowest Mg/Ca and Sr/Ca ratios were detected in the spines (mean Mg/Ca 37.5 ± 8.8 SD; Sr/Ca 1.8 ± 0.1). The components of the Aristotle's lantern (epiphyses, pyramids and rotulas) were characterised by the highest Mg levels (Mg/Ca 79.9 ± 6.0; 75.2 ± 9.1; 60.1 ± 3.8, respectively). It is likely that mouth parts experience greater mechanical pressure compared to other body parts, and the higher content of Mg in the Aristotle's lantern contributes to its robustness. We did not find any distinctive trends in the distribution of skeletal elements in the asteroid and ophiuroid skeletal parts. The heterogeneous concentrations of Mg and Sr in different skeleton parts of the echinoids suggest possible physiological regulation of the chemical composition rather than the composition only being influenced by the environment. We cannot recommend echinoderm skeletons as reliable indicators in palaeoenvironmental reconstructions due to the possible biological control of skeletal chemistry, which may interfere with the effect of environmental variables.

Ages and Nd, Sr isotopic systematics in the Sierran foothills ophiolite belt, CA: the Smartville and Feather River complexes

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

Shaw, H.F.; Niemeyer, S.

1985-01-01

Sm-Nd dating has shown the Kings-Kaweah ophiolite to be approx. 480 My old. Its Nd, Sr, and Pb isotopic compositions require an unusually old depleted mantle source. Samples from the Smartville and Feather River complexes have been analyzed in a search for similar highly depleted, early Paleozoic ophiolites in the northern foothills ophiolite belt. Six whole rocks from Smartville, encompassing representative lithologies, plus plagioclase and pyroxene mineral separates define a 183 +/- 22 My Sm-Nd isochron. This age, interpreted as the igneous age, is older than, but within error of, approx. 160 My U-Pb ages previously obtained from plagiogranite zirconmore » analyses. One diabase with unusually high Rb/Sr yields a depleted mantle Sr model age of 200 +/- 25 My, consistent with the Sm-ND age. These compositions are clearly oceanic in character but do not discriminate among possible tectonic settings for the formation of the Smartville complex. Sm-Nd data for flaser gabbros and related rocks from Feather River scatter about an approx. 230 My errorchron with element of/sub Nd/(T) = +6.3 to +8.7. Initial /sup 87/Sr//sup 86/Sr ranges from 0.7028 to 0.7031. These results indicate a complex history with initial isotopic heterogeneities and/or disturbances of the isotopic systems. If primary, the element of/sub Nd/ (T) values are somewhat low, suggesting a possible arc origin for these rocks. Neither the Smartville nor Feather R. complexes appear to be related to the Kings-Kaweah ophiolite which, so far, is unique among foothill ophiolites in having an early Paleozoic age and a clear MORB, as opposed to arc or marginal basin, isotopic signature.« less

Sleep-related vehicle crashes on low speed roads.

PubMed

Filtness, A J; Armstrong, K A; Watson, A; Smith, S S

2017-02-01

Very little is known about the characteristics of sleep related (SR) crashes occurring on low speed roads compared with current understanding of the role of sleep in crashes occurring on high speed roads e.g. motorways. To address this gap, analyses were undertaken to identify the differences and similarities between (1) SR crashes occurring on roads with low (≤60km/h) and high (≥100km/h) speed limits, and (2) SR crashes and not-SR crashes occurring on roads with low speed limits. Police reports of all crashes occurring on low and high speed roads over a ten year period between 2000 and 2009 were examined for Queensland, Australia. Attending police officers identified all crash attributes, including 'fatigue/fell asleep', which indicates that the police believe the crash to have a causal factor relating to falling asleep, sleepiness due to sleep loss, time of day, or fatigue. Driver or rider involvement in crashes was classified as SR or not-SR. All crash-associated variables were compared using Chi-square tests (Cramer's V=effect size). A series of logistic regression was performed, with driver and crash characteristics as predictors of crash category. A conservative alpha level of 0.001 determined statistical significance. There were 440,855 drivers or riders involved in a crash during this time; 6923 (1.6%) were attributed as SR. SR crashes on low speed roads have similar characteristics to those on high speed roads with young (16-24y) males consistently over represented. SR crashes on low speed roads are noticeably different to not-SR crashes in the same speed zone in that male and young novice drivers are over represented and outcomes are more severe. Of all the SR crashes identified, 41% occurred on low speed roads. SR crashes are not confined to high speed roads. Low speed SR crashes warrant specific investigation because they occur in densely populated areas, exposing a greater number of people to risk and have more severe outcomes than not-SR crashes on the same low speed roads. Copyright © 2016 Elsevier Ltd. All rights reserved.

TmSR-C, scavenger receptor class C, plays a pivotal role in antifungal and antibacterial immunity in the coleopteran insect Tenebrio molitor.

PubMed

Kim, Soo Gon; Jo, Yong Hun; Seong, Jeong Hwan; Park, Ki Beom; Noh, Mi Young; Cho, Jun Ho; Ko, Hye Jin; Kim, Chang Eun; Tindwa, Hamisi; Patnaik, Bharat Bhusan; Bang, In Seok; Lee, Yong Seok; Han, Yeon Soo

2017-10-01

Scavenger receptors (SRs) constitute a family of membrane-bound receptors that bind to multiple ligands. The SR family of proteins is involved in removing cellular debris, oxidized low-density lipoproteins, and pathogens. Specifically, class C scavenger receptors (SR-C) have also been reported to be involved in phagocytosis of gram-positive and -negative bacteria in Drosophila and viruses in shrimp. However, reports are unavailable regarding the role of SR-C in antifungal immune mechanisms in insects. In this study, a full-length Tenebrio molitor SR-C (TmSR-C) sequence was obtained by 5'- and 3'-Rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR). The TmSR-C full-length cDNA comprised 1671 bp with 5'- and 3'-untranslated regions of 23- and 107-bp, respectively. TmSR-C encodes a putative protein of 556 amino acid residues that is constitutively expressed in all tissues of late instar larvae and 2-day-old adults, with the highest transcript levels observed in hemocytes of larvae and adults. TmSR-C mRNA showed a 2.5-fold and 3-fold increase at 24 and 6 h after infection with Candida albicans and β-glucan, respectively. Immunoassay with TmSR-C polyclonal antibody showed induction of the putative protein in the cytosols of hemocytes at 3 h after inoculation of C. albicans. RNA interference (RNAi)-based gene silencing and phagocytosis assays were used to understand the role of TmSR-C in antifungal immunity. Silencing of TmSR-C transcripts reduced the survivability of late instar larvae at 2 days post-inoculation of C. albicans, Escherichia coli, or Staphylococcus aureus. Furthermore, in TmSR-C-silenced larvae, there was a decline in the rate of microorganism phagocytosis. Taken together, results of this study suggest that TmSR-C plays a pivotal role in phagocytosing not only fungi but also gram-negative and -positive bacteria in T. molitor. Copyright © 2017. Published by Elsevier Ltd.

An Experimental Investigation towards Improvement of Thermoelectric Properties of Strontium Titanate Ceramics

NASA Astrophysics Data System (ADS)

Mehdizadeh Dehkordi, Arash

The direct energy conversion between heat and electricity based on thermoelectric effects is a topic of long-standing interest in condensed matter materials science. Experimental and theoretical investigations in order to understand the mechanisms involved and to improve the materials properties and conversion efficiency have been ongoing for more than half a century. While significant achievements have been accomplished in improving the properties of conventional heavy element based materials (such as Bi2Te 3 and PbTe) as well as the discovery of new materials systems for the close-to-room temperature and intermediate temperatures, high-temperature applications of thermoelectrics is still limited to one materials system, namely SiGe. Recently, oxides have exhibited great potential to be investigated for high-temperature thermoelectric power generation. The objective of this dissertation is to synthesize and investigate both electronic and thermal transport in strontium titanate (SrTiO3) ceramics in order to experimentally realize its potential and to ultimately investigate the possibility of further improvement of the thermoelectric performance of this perovskite oxide for mid- to high temperature applications. Developing a synthesis strategy and tuning various synthesis parameters to benefit the thermoelectric transport form the foundation of this study. It is worth mentioning that the results of this study has been employed to prepare targets for pulsed-laser deposition (PLD) to study the thermoelectric properties of corresponding thin films and superlattice structures at Dr. Husam Alshareef's group at King Abdullah University of Science and Technology (KAUST), Saudi Arabia. Considering the broad range of functionality of SrTiO3, the findings of this work will surely benefit other fields of research and application of this functional oxide such as photoluminescence, ferroelectricity or mixed-ionic electronic conductivity. This dissertation will ultimately attempt to answer the question, "Is it possible to further improve the thermoelectric properties of SrTiO 3-based ceramics?". The organization of the dissertation is as follows: In Chapter 1, the fundamental concepts in the thermoelectric theory is explained. Second, we briefly review the characteristics of "good" thermoelectric materials and highlight the differences exist between SrTiO3 and conventional thermoelectric materials. In Chapter 2, SrTiO3 is introduced and the electronic and thermal properties arising from its crystal structure are discussed. Chapter 3 is dedicated to the fundamentals of measurements of the electronic and thermal transport properties which are the backbone of the current work. Our experimental results are presented in Chapter 4 and 5. The synthesis and processing techniques to prepare doped SrTiO3 powder and bulk polycrystalline ceramic are presented in Chapter 3. The optimizations of the synthesis and densification parameters involved are presented and discussed in this chapter as well. Significant improvement achieved in the thermoelectric figure of merit of Pr-doped SrTiO3 and the studies performed to understand the results are presented in Chapter 5. Concluding remarks and future work are discussed in Chapter 6.

Geochemical Overview of the East African Rift System

NASA Astrophysics Data System (ADS)

Furman, T.

2003-12-01

Mafic volcanics of the East African Rift System (EARS) record a protracted history of continental extension that is linked to mantle plume activity. The modern EARS traverses two post-Miocene topographic domes separated by a region of polyphase extension in northern Kenya and southern Ethiopia. Basaltic magmatism commenced ˜45 Ma in this highly extended region, while the onset of plume-related activity took place ˜30 Ma with eruption of flood basalts in central Ethiopia. A spatial and temporal synthesis of EARS volcanic geochemistry shows progressive lithospheric removal (by erosion and melting) as the degree of rifting increases, with basalts in the most highly extended areas recording melting of depleted asthenosphere. Plume contributions are indicated locally in the northern half of the EARS, but are absent from the southern half. The geochemical signatures are compatible with a physical model in which the entire EARS is fed by a discontinuous plume emanating from the core-mantle boundary as the South African Superswell. Quaternary basaltic lavas erupted in the Afar triangle, Red Sea and Gulf of Aden define the geochemical signature attributed to the Afar plume (87Sr/86Sr 0.7034-0.7037, 143Nd/144Nd 0.5129-0.5130; La/Nb 0.6-0.9; Nb/U 40-50). These suites commonly record mixing with ambient upper mantle having less radiogenic isotopes but generally overlapping incompatible trace element abundances. Within the Ethiopian dome both lithospheric and sub-lithoshperic contributions can be documented clearly; lithospheric contributions are manifest in more radiogenic isotope values (87Sr/86Sr up to 0.7050) and distinctive trace element abundances (e.g., La/Nb <2.0, Nb/U > 10). The degree of lithospheric contribution is lowest within the active Main Ethiopian Rift and increases towards the southern margin of the dome. The estimated depth of melting (65-75 km) is consistent with geophysical observations of lithospheric thickness. In regions of prolonged volcanism the lithospheric contributions and estimated melting depths decrease through time, corresponding to a higher degree of rifting. In the Kenyan dome, including the western rift, the degree of extension is low and lithospheric melting is the dominant source for basaltic magmatism. Mafic lavas from these regions have generally lower MgO but higher contents of alkalis, P2O5 and many incompatible trace elements than are observed in the Ethiopian Rift. High values of 87Sr/86Sr, 207Pb/204Pb and Zr/Hf relative to other parts of the EARS indicate melting of metasomatized lithosphere. Melting in this area occurs at depths up to 100+ km, consistent with the thick crustal section observed seismically. Between the topographic domes, basalts from the Turkana region record melting at shallow levels ( ˜35 km) consistent with seismic evidence for nearly complete rifting of the crustal section. The geochemistry of these lavas is dominated by asthenospheric source materials, with only minor lithospheric involvement. Temporal evolution of EARS geochemistry reflects progressive rifting of the thick craton. This change is manifest within lavas that are interpreted as plume-derived, as Tb/Yb values decrease from 30 Ma through the present. The modern thermal anomaly associated with Afar volcanism does not appear to extend below the shallow mantle, but may reflect a large blob of deep mantle material that became stuck to Africa 30 Ma and has contributed to regional volcanism ever since. Relative contributions from this deep mantle source, shallow asthenosphere and lithosphere are controlled by the extent of rifting and cannot be predicted solely on the basis of surface topography.

Episodic trace element and isotopic variations in historical Mauna Loa Lavas: Implications for magma and plume dynamics

NASA Astrophysics Data System (ADS)

Rhodes, J. M.; Hart, S. R.

Over the past 152 years, Mauna Loa volcano has erupted lavas with almost constant major element, and compatible and moderately incompatible trace element abundances at a given MgO content. This uniformity is attributed to continuing replenishment of a shallow magma reservoir. In contrast, incompatible element abundances and ratios, together with Sr, Nd and Pb isotopic ratios, vary systematically with time. The greatest rate of change occurred at a time (1843-1887) when Mauna Loa was vigorously active with high eruption rates, presumably a consequence of a high magma supply rate. Detailed analysis confirms what is evident from the isotopic data: that this open-system magmatism requires two or more parental magmas. One has the compositional attributes of lavas erupted in 1843, the other the characteristics of lavas erupted at the summit early in 1880. All other historical lavas can be considered as mixtures of these two end-members, modified by contemporaneous eruption and olivine crystallization. Both parental magmas have Sr, Pb and Nd isotopic ratios typical of magmas in the Hawaiian tholeiitic array, and intermediate between those of Kilauea and Koolau lavas, the end-members of the array. The 1843 parental magma has incompatible element ratios that are similar to, and overlap with the Koolau and Kilauea data. The inferred 1880 parental magma, however, is more depleted than the 1843 parental magma (and most other Hawaiian lavas), and is also isotopically closer to the Kilauea end-member of the tholeiitic array. The origin of these parental magmas is discussed in terms of melting within a radially heterogeneous plume in which the heterogeneity may develop at the source or through subsequent mantle entrainment. Two models are explored, both depend on the location of Mauna Loa at, or close to the plume margin. In the simplest case the parental magmas are produced by progressive melting of the heterogeneous outer plume. The second model is more dynamic, involving melt production and re-equilibration in a diverging, or inclined, plume.

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.

Evaluation of carbonate diagenesis: A comparative study of minor elements, trace elements, and rare-earth elements (REE + Y) between Pleistocene corals and matrices from Grand Cayman, British West Indies

NASA Astrophysics Data System (ADS)

Li, Rong; Jones, Brian

2014-12-01

On Grand Cayman, the Pleistocene Ironshore Formation consists of six unconformity-bounded units of limestones that have been partially or completely altered to calcite by post-depositional meteoric diagenesis. In order to examine the diagenetic history from the perspective of geochemical elements, the concentrations of minor element (Sr, Na, Mg), trace elements (Ba, Fe, Mn, Al, Si), and rare-earth elements (REE) and yttrium (Y) were determined for 105 corals and 84 matrices collected from the Rogers Wreck Point (RWP), Western Onshore area (WO), and offshore George Town (GT) areas. With the transformation of aragonite to calcite, the Sr, Na, and Ba values decreased, but Mg increased, which are indicative of diagenetic alteration in an open water system. Due to intrinsic "vital effects" and the extrinsic diagenetic environment, the variations of Sr, Na, Ba, and Mg concentrations between Acropora and Montastrea from the GT area are different to those of their counterparts from RWP and WO. The signatures of Sr, Na, Ba, and Mg are in good agreement with the diagenetic history as determined from petrographic and stable isotopic criteria. The REE + Y (REY) concentrations (ΣREY) are higher in the matrices (0.2-6.9 ppm, average 2.6 ppm) than in the associated corals (0.1-5.4 ppm, average 0.6 ppm). Shale-normalized REY patterns of the Pleistocene Ironshore Formation are similar to those of oxygenated seawater, which are characterized by (1) light REE depletion relative to heavy REE (average DySN/SmSN = 1.7, n = 35), (2) positive La anomalies (average Pr/Pr* = 1.17, n = 53), and (3) negative Ce anomalies (average Ce/Ce* = 0.49, n = 53). The preserved seawater-like REY distribution pattern, the lack of correlation between ΣREY and mineralogy, and the lack of correlation between ΣREY and diagenesis-sensitive stable oxygen isotope (δ18O) indicate that meteoric diagenesis did not have a major impact on the REY distribution patterns. The matrices and corals in the GT area, compared to their counterparts from RWP and WO, have relatively less depleted LREE and lower Y in REY distribution pattern, suggesting contamination by minor amounts of detrital sediments. This is supported by the fact that limestones from the GT area contain abnormally high contents of detrital elements (Al, Si). The variations in ΣREY in carbonate rocks from locality to locality probably reflect variations that existed in the local depositional environments where these deposits originally formed.

Crystal residence times from trace element zoning in plagioclase reveal changes in magma transfer dynamics at Mt. Etna during the last 400 years

NASA Astrophysics Data System (ADS)

Viccaro, Marco; Barca, Donatella; Bohrson, Wendy A.; D'Oriano, Claudia; Giuffrida, Marisa; Nicotra, Eugenio; Pitcher, Bradley W.

2016-04-01

Trace element zoning in plagioclase of selected alkaline lavas from the historic (1607-1892 AD) and recent (1983-2013 AD) activity of Mt. Etna volcano has been used to explore the possible role that volcano-tectonics exert on magma transfer dynamics. The observed textural characteristics of crystals include near-equilibrium textures (i.e., oscillatory zoning) and textures with variable extent of disequilibrium (patchy zoning, coarse sieve textures and dissolved cores). Historic crystals exhibit lower K concentrations at lower anorthite contents, a feature in agreement with the general more potassic character of the recent lavas if compared to the historic products. Historic plagioclases have statistically higher Ba and lower Sr concentrations than the recent crystals, which result in different Sr/Ba ratios for the two suites of plagioclase. Variations in the anorthite content along core-to-rim profiles obtained on crystals with different types of textures for both the historic and recent eruptive periods were evaluated particularly versus Sr/Ba. At comparable average An contents, crystals characterized by oscillatory zoning, which are representative of near-equilibrium crystallization from the magma, display distinct Sr/Ba ratios. We suggest that these features are primarily related to recharge of a new, geochemically-distinct magma into the storage and transport system of the volcano. In addition to distinct trace element and textural characteristics of plagioclase, Sr diffusion modeling for plagioclase suggests that residence times are generally shorter for crystals found in recently erupted lavas (25-77 years, average 43 years) compared to those of the historic products (43-163 years, average 99 years). Shorter residences times correlate with gradual increases in eruption volume and eruption frequency rates through time. We attribute these features to an increasing influence, since the 17th century, of extensional tectonic structures within the upper 10 km of the Etnean crust, which have promoted shorter residence times and higher eruption frequency.

Relationships between water and paddlefish Polyodon spathula dentary elemental and stable-isotopic signatures: potential application for reconstructing environmental history

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

Bock, Lindsey R.; Whitledge, Gregory W.; Pracheil, Brenda M.

The objectives of this study were to characterize relationships between water and paddlefish Polyodon spathula dentary Sr:Ca, δ 18O and stable hydrogen isotope ratio (δD) to determine the accuracy with which individual P. spathula could be assigned to their collection locations using dentary-edge Sr:Ca, δD and δ 18O. A laboratory experiment was also conducted to determine whether dentary Sr:Ca in age 0 year P. spathula would reflect shifts in water Sr:Ca to which fish were exposed. Significant linear relationships between water and dentary Sr:Ca, δD and δ 18O were observed, although the relationship between water and dentary δ 18O wasmore » weaker than those for Sr:Ca and δD. Classification success for individual fish to collection locations that differed in water Sr:Ca, δD and δ 18O ranged from 86 to 100% based on dentary-edge Sr:Ca, δD and δ18O. Dentary Sr:Ca increased significantly in laboratory-reared age 0 year P. spathula following 4 weeks of exposure to elevated water Sr:Ca; dentary Sr:Ca of fish held in water with elevated Sr:Ca was also significantly higher than that of control fish reared in ambient laboratory water. Results indicated that P. spathula dentaries reflect water signatures for commonly-applied natural chemical markers and strongly suggest that dentary microchemistry and stable-isotopic compositions will be applicable for reconstructing P. spathula environmental history in locations where sufficient spatial differences in water chemistry occur.« less

Relationships between water and paddlefish Polyodon spathula dentary elemental and stable-isotopic signatures: potential application for reconstructing environmental history

DOE PAGES

Bock, Lindsey R.; Whitledge, Gregory W.; Pracheil, Brenda M.; ...

2016-07-26

The objectives of this study were to characterize relationships between water and paddlefish Polyodon spathula dentary Sr:Ca, δ 18O and stable hydrogen isotope ratio (δD) to determine the accuracy with which individual P. spathula could be assigned to their collection locations using dentary-edge Sr:Ca, δD and δ 18O. A laboratory experiment was also conducted to determine whether dentary Sr:Ca in age 0 year P. spathula would reflect shifts in water Sr:Ca to which fish were exposed. Significant linear relationships between water and dentary Sr:Ca, δD and δ 18O were observed, although the relationship between water and dentary δ 18O wasmore » weaker than those for Sr:Ca and δD. Classification success for individual fish to collection locations that differed in water Sr:Ca, δD and δ 18O ranged from 86 to 100% based on dentary-edge Sr:Ca, δD and δ18O. Dentary Sr:Ca increased significantly in laboratory-reared age 0 year P. spathula following 4 weeks of exposure to elevated water Sr:Ca; dentary Sr:Ca of fish held in water with elevated Sr:Ca was also significantly higher than that of control fish reared in ambient laboratory water. Results indicated that P. spathula dentaries reflect water signatures for commonly-applied natural chemical markers and strongly suggest that dentary microchemistry and stable-isotopic compositions will be applicable for reconstructing P. spathula environmental history in locations where sufficient spatial differences in water chemistry occur.« less

87Sr/86Sr and 143Nd/144Nd for disentangling anthropogenic and natural REE contributions in river water during flood events.

NASA Astrophysics Data System (ADS)

Hissler, Christophe; Stille, Peter; Pfister, Laurent

2017-04-01

The sustainable management of water resources is one of the greatest challenges of the 21st century. Water is a vital resource that is increasingly put under pressure from multiple perspectives. While the global population is on the rise, socio-economic development makes equally rapid progress - eventually compromising access to clean water bodies. Multiple pollution sources constitute an immediate threat to aquatic ecosystems and are likely to cause long lasting contaminations of water bodies that are critical for drinking and/or irrigation water production. There is a pressing need for an adequate quantification of anthropogenic impacts on the critical zone of river basins and the identification of the temporal dynamics of these impacts. As an example, despite the work done to assess the environmental impact of REE pollutions in larger river systems, we are still lacking information on the dynamics of these anthropogenic compounds in relation to rapid hydrological changes. Filling these knowledge gaps is a pre-requisite for the design and implementation of sustainable water resources management strategies. In order to better constrain the relative contributions of both anthropogenic and geogenic trace element sources we propose using a multitracer approach combining elemental and 87Sr/86Sr, 143Nd/144Nd, and 206Pb/207Pb isotopic ratios. The use of these three separate isotopic systems together with REE concentrations is new in the field of anthropogenic source identification in river systems. We observed enrichments in Anthropogenic Rare Earth Elements (AREE) for dissolved Gd and suspended Nd loads of river water. With increasing discharge, AREE anomalies progressively disappeared and gave way to the geogenic chemical signature of the basin in both dissolved and suspended loads. The isotopic data confirm these observations and shed new light on the trace elements sources. On the one hand, dissolved loads have peculiar isotopic characteristics and carry mainly limestone-derived and anthropogenic Sr and Nd as well as significant amounts of anthropogenic Pb. On the other hand, the results clearly indicate that anthropogenic contributions impact the suspended loads in all hydrological conditions. This study demonstrates that (i) the composition of the AREE pool is characteristic of a given river basin and controlled by the different anthropogenic contributions located in a specific study area and (ii) the anthropogenic contributions to the river may change not only Pb, but also Sr and Nd isotopic compositions in both dissolved and suspended loads. This is of importance for future provenance studies in the critical zone of polluted river basins.

An underdamped stochastic resonance method with stable-state matching for incipient fault diagnosis of rolling element bearings

NASA Astrophysics Data System (ADS)

Lei, Yaguo; Qiao, Zijian; Xu, Xuefang; Lin, Jing; Niu, Shantao

2017-09-01

Most traditional overdamped monostable, bistable and even tristable stochastic resonance (SR) methods have three shortcomings in weak characteristic extraction: (1) their potential structures characterized by single stable-state type are insufficient to match with the complicated and diverse mechanical vibration signals; (2) they vulnerably suffer the interference from multiscale noise and largely depend on the help of highpass filters whose parameters are selected subjectively, probably resulting in false detection; and (3) their rescaling factors are fixed as constants generally, thereby ignoring the synergistic effect among vibration signals, potential structures and rescaling factors. These three shortcomings have limited the enhancement ability of SR. To explore the SR potential, this paper initially investigates the SR in a multistable system by calculating its output spectral amplification, further analyzes its output frequency response numerically, then examines the effect of both damping and rescaling factors on output responses and finally presents a promising underdamped SR method with stable-state matching for incipient bearing fault diagnosis. This method has three advantages: (1) the diversity of stable-state types in a multistable potential makes it easy to match with various vibration signals; (2) the underdamped multistable SR, equivalent to a moving nonlinear bandpass filter that is dependent on the rescaling factors, is able to suppress the multiscale noise; and (3) the synergistic effect among vibration signals, potential structures and rescaling and damping factors is achieved using quantum genetic algorithms whose fitness functions are new weighted signal-to-noise ratio (WSNR) instead of SNR. Therefore, the proposed method is expected to possess good enhancement ability. Simulated and experimental data of rolling element bearings demonstrate its effectiveness. The comparison results show that the proposed method is able to obtain higher amplitude at target frequency and larger output WSNR, and performs better than traditional SR methods.

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.

An internally consistent inverse model to calculate ridge-axis hydrothermal fluxes

NASA Astrophysics Data System (ADS)

Coogan, L. A.; Dosso, S.

2010-12-01

Fluid and chemical fluxes from high-temperature, on-axis, hydrothermal systems at mid-ocean ridges have been estimated in a number of ways. These generally use simple mass balances based on either vent fluid compositions or the compositions of altered sheeted dikes. Here we combine these approaches in an internally consistent model. Seawater is assumed to enter the crust and react with the sheeted dike complex at high temperatures. Major element fluxes for both the rock and fluid are calculated from balanced stoichiometric reactions. These reactions include end-member components of the minerals plagioclase, pyroxene, amphibole, chlorite and epidote along with pure anhydrite, quartz, pyrite, pyrrhotite, titanite, magnetite, ilmenite and ulvospinel and the fluid species H2O, Mg2+, Ca2+, Fe2+, Na+, Si4+, H2S, H+ and H2. Trace element abundances (Li, B, K, Rb, Cs, Sr, Ba, U, Tl, Mn, Cu, Zn, Co, Ni, Pb and Os) and isotopic ratios (Li, B, O, Sr, Tl, Os) are calculated from simple mass balance of a fluid-rock reaction. A fraction of the Cu, Zn, Pb, Co, Ni, Os and Mn in the fluid after fluid-rock reaction is allowed to precipitate during discharge before the fluid reaches the seafloor. S-isotopes are tied to mineralogical reactions involving S-bearing phases. The free parameters in the model are the amounts of each mineralogical reaction that occurs, the amounts of the metals precipitated during discharge, and the water-to-rock ratio. These model parameters, and their uncertainties, are constrained by: (i) mineral abundances and mineral major element compositions in altered dikes from ODP Hole 504B and the Pito and Hess Deep tectonic windows (EPR crust); (ii) changes in dike bulk-rock trace element and isotopic compositions from these locations relative to fresh MORB glass compositions; and (iii) published vent fluid compositions from basalt-hosted high-temperature ridge axis hydrothermal systems. Using a numerical inversion algorithm, the probability density of different model parameter sets has been computed and thus the probability of different fluid and chemical fluxes. Most data can be fit by the model within their uncertainty. The entire dataset is best-fit with a water-to-rock mass ratio between 1.3 and 2.1 (~1 to 1.5 x10**13 kg yr-1) implying a substantial fraction of the magmatic (latent) heat available to drive the axial hydrothermal system is extracted by these systems. Many element fluxes are better constrained than in previous studies (e.g., Sr: 2 to 7 x10**8 moles yr-1; Ca: 2 to 7 x10**11 moles yr-1). Future developments will use experimental data to further constrain the model.

Linking major and trace element headwater stream concentrations to DOC release and hydrologic conditions in a bog and peaty riparian zone

NASA Astrophysics Data System (ADS)

Broder, Tanja; Biester, Harald

2017-04-01

Peatlands and organic-rich riparian zones are known to export large amounts of dissolved organic carbon (DOC) to surface water. In organic-rich, acidic headwater streams main carriers for element export are dissolved organic matter (DOM) and organic-iron complexes. In this environment DOM might also act as major carrier for metals, which otherwise may have a low solubility. This study examines annual and short term event-based variations of major and trace elements in a headwater catchment. Patterns are used to trace hydrological pathways and element sources under different hydrologic preconditions. Furthermore, it elucidates the importance of DOC as carrier of different elements in a bog and a peaty riparian catchment. The study was conducted in a small headwater stream draining an ombrotrophic peatland with an adjacent forested area with peaty riparian soils in the Harz Mountains (Germany). Discharge sampling was conducted weekly at two sites from snowmelt to begin of snowfall and in high resolution during selected discharge events in 2013 and 2014. Element concentrations were measured by means of ICP-MS and ICP-OES. A PCA was performed for each site and for annual and event datasets. Results show that a large number of element concentrations strongly correlate with DOC concentrations at the bog site. Even elements like Ca and Mg, which are known to have a low affinity to DOC. Congruently, the first principal component integrates the DOC pattern (element loadings > 0.8: Ca, Fe, Mg, Mn, Zn, As, Sr, Cd, DOC) and explained about 35 % of total variance and even 50 % during rain events (loadings > 0.8: Al, Ca, Fe, Mg, Mn, Zn, Li, Co, As, Sr, Cd, Pb, DOC). The study cannot verify that all correlating elements bind to DOC. It is likely that also a common mobilization pattern in the upper peat layer by plant decomposition causes the same response to changes in hydrologic pathways. Additionally, a low mineral content and an enrichment of elements like Fe and Mn in the upper peat layers due to prevailing redox conditions might play a major role in a bog environment. At the peaty riparian zone only Ca, Fe, and Sr strongly correlated with DOC over the annual record. The PCA of the annual record display no clear DOC component here, but indicates that DOC is influenced by Component one (element loadings > 0.8: Ca, Mg, Zn, Co, Sr) and two (Al, V, La, Pb, U) suggesting different DOC sources in the peaty riparian zone. A large number of elements correlate with DOC during rain event sampling at the riparian zone. In contrast to the bog site the event-based riparian zone PCA distinguished a clear discharge related component with mineral, groundwater related elements (K, Rb, In, Cs, NO3- and SO42-). Pattern of the mineral and DOC components prove that during base flow discharge is generated in a shallow groundwater layer and successively increases upward to the organic-rich upper soil layer with increasing discharge. Contrarily, bog element pattern confirm a dominating surface-near discharge, due to high hydraulic conductivities.

The effect of drinking water quality on the health and longevity of people-A case study in Mayang, Hunan Province, China

NASA Astrophysics Data System (ADS)

Lu, J.; Yuan, F.

2017-08-01

Drinking water is an important source for trace elements intake into human body. Thus, the drinking water quality has a great impact on people’s health and longevity. This study aims to study the relationship between drinking water quality and human health and longevity. A longevity county Mayang in Hunan province, China was chosen as the study area. The drinking water and hair of local centenarians were collected and analyzed the chemical composition. The drinking water is weak alkaline and rich in the essential trace elements. The daily intakes of Ca, Cu, Fe, Se, Sr from drinking water for residents in Mayang were much higher than the national average daily intake from beverage and water. There was a positive correlation between Ni and Pb in drinking water and Ni and Pb in hair. There were significant correlations between Cu, K in drinking water and Ba, Ca, Mg, Sr in the hair at the 0.01 level. The concentrations of Mg, Sr, Se in drinking water showed extremely significant positive relation with two centenarian index 100/80% and 100/90% correlation. Essential trace elements in drinking water can be an important factor for local health and longevity.

Potential Effects of Hydroelectric Dam Development in the Mekong River Basin on the Migration of Siamese Mud Carp (Henicorhynchus siamensis and H. lobatus) Elucidated by Otolith Microchemistry

PubMed Central

Fukushima, Michio; Jutagate, Tuantong; Grudpan, Chaiwut; Phomikong, Pisit; Nohara, Seiichi

2014-01-01

The migration of Siamese mud carp (Henicorhynchus siamensis and H. lobatus), two of the most economically important fish species in the Mekong River, was studied using an otolith microchemistry technique. Fish and river water samples were collected in seven regions throughout the whole basin in Thailand, Laos and Cambodia over a 4 year study period. There was coherence between the elements in the ambient water and on the surface of the otoliths, with strontium (Sr) and barium (Ba) showing the strongest correlation. The partition coefficients were 0.409–0.496 for Sr and 0.055 for Ba. Otolith Sr-Ba profiles indicated extensive synchronized migrations with similar natal origins among individuals within the same region. H. siamensis movement has been severely suppressed in a tributary system where a series of irrigation dams has blocked their migration. H. lobatus collected both below and above the Khone Falls in the mainstream Mekong exhibited statistically different otolith surface elemental signatures but similar core elemental signatures. This result suggests a population originating from a single natal origin but bypassing the waterfalls through a passable side channel where a major hydroelectric dam is planned. The potential effects of damming in the Mekong River are discussed. PMID:25099147

Multi-isotope tracers to investigate processes in the Elbe, Weser and Ems river catchment using B, Mo, Sr, and Pb isotope ratios assessed by MC ICP-MS

NASA Astrophysics Data System (ADS)

Irrgeher, Johanna; Reese, Anna; Zimmermann, Tristan; Prohaska, Thomas; Retzmann, Anika; Wieser, Michael E.; Zitek, Andreas; Proefrock, Daniel

2017-04-01

Environmental monitoring of complex ecosystems requires reliable sensitive techniques based on sound analytical strategies to identify the source, fate and sink of elements and matter. Isotopic signatures can serve to trace pathways by making use of specific isotopic fingermarks or to distinguish between natural and anthropogenic sources. The presented work shows the potential of using the isotopic variation of Sr, Pb (as well-established isotopic systems), Mo and B (as novel isotopic system) assessed by MC ICP-MS in water and sediment samples to study aquatic ecosystem transport processes. The isotopic variation of Sr, Pb, Mo and B was determined in different marine and estuarine compartments covering the catchment of the German Wadden Sea and its main tributaries, the Elbe, Weser and Ems River. The varying elemental concentrations, the complex matrix and the expected small variations in the isotopic composition required the development and application of reliable analytical measurement approaches as well as suited metrological data evaluation strategies. Aquatic isoscapes were created using ArcGIS® by relating spatial isotopic data with geographical and geological maps. The elemental and isotopic distribution maps show large variation for different parameters and also reflect the numerous impact factors (e.g. geology, anthropogenic sources) influencing the catchment area.

Incorporation of Mg, Sr, Ba, U, and B in High-Mg Calcite Benthic Foraminifers Cultured Under Controlled pCO2

NASA Astrophysics Data System (ADS)

Not, C.; Thibodeau, B.; Yokoyama, Y.

2018-01-01

Measurement of elemental ratios (E/Ca) has been performed in two symbiont-bearing species of high-Mg calcite benthic foraminifers (hyaline, Baculogypsina sphaerulata and porcelaneous, Amphisorus hemprichii), cultured under five pCO2 levels, representing preindustrial, modern, and three predicted future values. E/Ca ratios were analyzed by Laser Ablation coupled with Inductively Coupled Plasma Mass Spectrometer (LA-ICP-MS). We measured several E/Ca, such as Mg/Ca, Sr/Ca, Ba/Ca, U/Ca, and B/Ca simultaneously. We observed that high-Mg calcite benthic foraminifers possess higher E/Ca than low-Mg calcite foraminifers, irrespective of their calcification mode (hyaline or porcelaneous). In both modes of calcification, Mg, Sr, Ba, U, and B incorporation could be controlled by Rayleigh fractionation. However, more data are needed to validate and quantify the relative importance of this process and closely investigate the presence/absence of other mechanism. Therefore, it highlights the need for a multielemental approach when looking at trace element incorporation. Finally, no significant relationship was observed between the different ratios and the pCO2 of the water, suggesting that none of the Mg/Ca, Sr/Ca, Ba/Ca, U/Ca, and B/Ca is sensitive to bottom water pCO2 or pH for these species.

Formation of carbonatite-related giant rare-earth-element deposits by the recycling of marine sediments

PubMed Central

Hou, Zengqian; Liu, Yan; Tian, Shihong; Yang, Zhiming; Xie, Yuling

2015-01-01

Carbonatite-associated rare-earth-element (REE) deposits are the most significant source of the world’s REEs; however, their genesis remains unclear. Here, we present new Sr-Nd-Pb and C-O isotopic data for Cenozoic carbonatite-hosted giant REE deposits in southwest China. These REE deposits are located along the western margin of the Yangtze Craton that experienced Proterozoic lithospheric accretion, and controlled by Cenozoic strike-slip faults related to Indo-Asian continental collision. The Cenozoic carbonatites were emplaced as stocks or dykes with associated syenites, and tend to be extremely enriched in Ba, Sr, and REEs and have high 87Sr/86Sr ratios (>0.7055). These carbonatites were likely formed by melting of the sub-continental lithospheric mantle (SCLM), which had been previously metasomatized by high-flux REE- and CO2-rich fluids derived from subducted marine sediments. The fertility of these carbonatites depends on the release of REEs from recycled marine sediments and on the intensity of metasomatic REE refertilization of the SCLM. We suggest that cratonic edges, particularly along ancient convergent margins, possess the optimal configuration for generating giant REE deposits; therefore, areas of metamorphic basement bounded or cut by translithospheric faults along cratonic edges have a high potential for such deposits. PMID:26035414

The alteration of interelemental ratios in myocardium under the congenital heart disease (SRXRF)

NASA Astrophysics Data System (ADS)

Trunova, V. A.; Zvereva, V. V.; Okuneva, G. N.; Levicheva, E. N.

2007-05-01

It is the myocardium that bears the basic functional loading during heart working, including muscle contractility and enzyme activity. The elemental concentrations in myocardium tissue of heart were determined by SRXRF technique. Our investigation is systematical: the elemental content in each compartment (left and right ventricles, left and right auricles) of hearts of healthy and diseased children (congenital heart diseases, transposition of main vessels (TMV)) was analyzed. The elemental distribution in myocardium of four heart chambers of human fetuses was also analyzed. Following elements were determined: S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr. It was revealed that the elemental concentrations in myocardium of both ventricles are almost constant in heart of fetuses and healthy children. The transition from pre-natal study (fetus) to post-natal study is accompanied by the redistribution of chemical elements in myocardium. The higher concentrations of S, Fe, Ca, Sr and Cu in myocardium of children are observed, the content of K, Br, Rb and especially Se is lower than in heart of fetuses. The elemental distribution in myocardium of children TMV is considerably different in comparison with the healthy children: the higher levels of Cu are observed. The content of Se is lower.

A preliminary analysis of trace-elemental signatures in statoliths of different spawning cohorts for Dosidicus gigas off EEZ waters of Chile

NASA Astrophysics Data System (ADS)

Liu, Bilin; Chen, Xinjun; Fang, Zhou; Hu, Song; Song, Qian

2015-12-01

We applied solution-based ICP-MS method to quantify the trace-elemental signatures in statoliths of jumbo flying squid, Dosidius gigas, which were collected from the waters off northern and central Chile during the scientific surveys carried out by Chinese squid jigging vessels in 2007 and 2008. The age and spawning date of the squid were back-calculated based on daily increments in statoliths. Eight elemental ratios (Sr/Ca, Ba/Ca, Mg/Ca, Mn/Ca, Na/Ca, Fe/Ca, Cu/Ca and Zn/Ca) were analyzed. It was found that Sr is the second most abundant element next to Ca, followed by Na, Fe, Mg, Zn, Cu, Ba and Mn. There was no significant relationship between element/Ca and sea surface temperature (SST) and sea surface salinity (SSS), although weak negative or positive tendency was found. MANOVA analysis showed that multivariate elemental signatures did not differ among the cohorts spawned in spring, autumn and winter, and no significant difference was found between the northern and central sampling locations. Classification results showed that all individuals of each spawned cohorts were correctly classified. This study demonstrates that the elemental signatures in D. gigas statoliths are potentially a useful tool to improve our understanding of its population structure and habitat environment.

Geochemical evidence for the provenance of aeolian deposits in the Qaidam Basin, Tibetan Plateau

NASA Astrophysics Data System (ADS)

Du, Shisong; Wu, Yongqiu; Tan, Lihua

2018-06-01

The main purpose of this study is to analyse the material source of different grain-size components of dune sand in the Qaidam Basin. We determined the trace and rare earth element (REE) compositions and Sr-Nd isotopic compositions of the coarse (75-500 μm) and fine (<75 μm) fractions of surface sediment samples. The comparison of the immobile trace element and REE compositions, Sr-Nd isotopic compositions and multidimensional scaling (MDS) results of the dune sands with those of different types of sediments in potential source areas revealed the following information. (1) The fine- and coarse-grained fractions of dune sands in the Qaidam Basin exhibit distinctly different elemental concentrations, elemental patterns and characteristic parameters of REE. Moreover, Sr-Nd isotopic differences also exist between different grain-size fractions of aeolian sand, which means that different grain-size fractions of these dune sands have different source areas. (2) The geochemical characteristics of the coarse particles of dune sand exhibit obvious regional heterogeneity and generally record a local origin derived from local fluvial sediments and alluvial/proluvial sediments. The coarse- and fine-grained dune sand in the southern Qaidam Basin mainly came from Kunlun Mountains, whereas the coarse- and fine-grained dune sand in the northeastern Qaidam Basin mainly came from Qilian Mountains. (3) The fine-grained fractions of sediments throughout the entire Qaidam Basin may have been affected by the input of foreign materials from the Tarim Basin.

Mixing of Marine and Terrestrial Sources of Strontium in Coastal Environments

NASA Astrophysics Data System (ADS)

Ryan, Saskia; Crowley, Quentin; Deegan, Eileen; Snoeck, Christophe

2017-04-01

87Sr/86Sr from bulk soils, soil extracts and plant material have been used to investigate and quantify the extent of marine-derived Sr in the terrestrial biosphere. Samples were collected along coastal transects and 87Sr/86Sr biosphere values (plant and soil) converge to marine values with increasing proximity to the coast. R2values indicate highly significant trends in certain regions. The National Soils Database (NSDB), TELLUS and TELLUS Border datasets, all of which are geochemical surveys have been employed to further test the extent of marine elemental contribution. Collectively these data cover all of Ireland and Northern Ireland, with varying degrees of sampling density. A strong spatial correlation exists between the Chemical Index of Alteration (CIA; (Al2O3-(CaO*+Na2O)-K2O)) in topsoil (CIA <60; 27% n = 11651) and areas of blanket peat. The enrichment of Ca and Na in these regions would suggest a significant marine geochemical contribution. Topsoil CIA can therefore be used to identify areas likely to feature significant marine inputs and identify regions where the 87Sr/86Sr budget may deviate from bedrock values.

Imaging and tuning polarity at SrTiO 3 domain walls

DOE PAGES

Frenkel, Yiftach; Haham, Noam; Shperber, Yishai; ...

2017-09-18

Electrostatic fields tune the ground state of interfaces between complex oxide materials. Electronic properties, such as conductivity and superconductivity, can be tuned and then used to create and control circuit elements and gate-defined devices. Here in this paper, we show that naturally occurring twin boundaries, with properties that are different from their surrounding bulk, can tune the LaAlO 3/SrTiO 3 interface 2DEG at the nanoscale. In particular, SrTiO 3 domain boundaries have the unusual distinction of remaining highly mobile down to low temperatures, and were recently suggested to be polar. Here we apply localized pressure to an individual SrTiO 3more » twin boundary and detect a change in LaAlO 3/SrTiO 3 interface current distribution. Our data directly confirm the existence of polarity at the twin boundaries, and demonstrate that they can serve as effective tunable gates. As the location of SrTiO 3 domain walls can be controlled using external field stimuli, our findings suggest a novel approach to manipulate SrTiO 3-based devices on the nanoscale.« less

87Sr solid-state NMR as a structurally sensitive tool for the investigation of materials: antiosteoporotic pharmaceuticals and bioactive glasses.

PubMed

Bonhomme, Christian; Gervais, Christel; Folliet, Nicolas; Pourpoint, Frédérique; Diogo, Cristina Coelho; Lao, Jonathan; Jallot, Edouard; Lacroix, Joséphine; Nedelec, Jean-Marie; Iuga, Dinu; Hanna, John V; Smith, Mark E; Xiang, Ye; Du, Jincheng; Laurencin, Danielle

2012-08-01

Strontium is an element of fundamental importance in biomedical science. Indeed, it has been demonstrated that Sr(2+) ions can promote bone growth and inhibit bone resorption. Thus, the oral administration of Sr-containing medications has been used clinically to prevent osteoporosis, and Sr-containing biomaterials have been developed for implant and tissue engineering applications. The bioavailability of strontium metal cations in the body and their kinetics of release from materials will depend on their local environment. It is thus crucial to be able to characterize, in detail, strontium environments in disordered phases such as bioactive glasses, to understand their structure and rationalize their properties. In this paper, we demonstrate that (87)Sr NMR spectroscopy can serve as a valuable tool of investigation. First, the implementation of high-sensitivity (87)Sr solid-state NMR experiments is presented using (87)Sr-labeled strontium malonate (with DFS (double field sweep), QCPMG (quadrupolar Carr-Purcell-Meiboom-Gill), and WURST (wideband, uniform rate, and smooth truncation) excitation). Then, it is shown that GIPAW DFT (gauge including projector augmented wave density functional theory) calculations can accurately compute (87)Sr NMR parameters. Last and most importantly, (87)Sr NMR is used for the study of a (Ca,Sr)-silicate bioactive glass of limited Sr content (only ~9 wt %). The spectrum is interpreted using structural models of the glass, which are generated through molecular dynamics (MD) simulations and relaxed by DFT, before performing GIPAW calculations of (87)Sr NMR parameters. Finally, changes in the (87)Sr NMR spectrum after immersion of the glass in simulated body fluid (SBF) are reported and discussed.

Trace elements distribution and post-mortem intake in human bones from Middle Age by total reflection X-ray fluorescence*1

NASA Astrophysics Data System (ADS)

Carvalho, M. L.; Marques, A. F.; Lima, M. T.; Reus, U.

2004-08-01

The purpose of the present work is to investigate the suitability of TXRF technique to study the distribution of trace elements along human bones of the 13th century, to conclude about environmental conditions and dietary habits of old populations and to study the uptake of some elements from the surrounding soil. In this work, we used TXRF to quantify and to make profiles of the elements through long bones. Two femur bones, one from a man and another from a woman, buried in the same grave were cross-sectioned in four different points at a distance of 1 cm. Microsamples of each section were taken at a distance of 1 mm from each other. Quantitative analysis was performed for Ca, Mn, Fe, Cu, Zn, Sr, Ba and Pb. Very high concentrations of Mn and Fe were obtained in the whole analysed samples, reaching values higher than 2% in some samples of trabecular tissue, very much alike to the concentrations in the burial soil. A sharp decrease for both elements was observed in cortical tissue. Zn and Sr present steady concentration levels in both kinds of bone tissues. Pb and Cu show very low concentrations in the inner tissue of cortical bone. However, these concentrations increase in the regions in contact to trabecular tissue and external surface in contact with the soil, where high levels of both elements were found. We suggest that contamination from the surrounding soil exists for Mn and Fe in the whole bone tissue. Pb can be both from post-mortem and ante-mortem origin. Inner compact tissue might represent in vivo accumulation and trabecular one corresponds to uptake during burial. The steady levels of Sr and Zn together with soil concentration lower levels for these elements may allow us to conclude that they are originated from in vivo incorporation in the hydroxyapatite bone matrix.

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.

Nanocomposite Porous Microcarriers Based on Strontium-Substituted HA- g-Poly(γ-benzyl-l-glutamate) for Bone Tissue Engineering.

PubMed

Yan, Shifeng; Xia, Pengfei; Xu, Shenghua; Zhang, Kunxi; Li, Guifei; Cui, Lei; Yin, Jingbo

2018-05-04

Porous microcarriers have aroused increasing attention recently, which can create a protected environment for sufficient cell seeding density, facilitate oxygen and nutrient transfer, and well support the cell attachment and growth. In this study, porous microcarriers fabricated from the strontium-substituted hydroxyapatite- graft-poly(γ-benzyl-l-glutamate) (Sr10-HA- g-PBLG) hybrid nanocomposite were developed. The surface grating of PBLG, the micromorphology and element distribution, mechanical strength, in vitro degradation, and Sr 2+ ion release of the obtained Sr10-HA- g-PBLG porous microcarriers were investigated, respectively. The grafting ratio and the molecular weight of the grafted PBLG of Sr10-HA- g-PBLG could be effectively controlled by varying the initial ratio of BLG-NCA to Sr10-HA-NH 2 . The microcarriers exhibited a highly porous and interconnected microstructure with the porosity of about 90% and overall density of 1.03-1.06 g/cm 3 . Also, the degradation rate of Sr10-HA-PBLG microcarriers could be effectively controlled and long-term Sr 2+ release was obtained. The Sr10-HA-PBLG microcarriers allowed cells adhesion, infiltration, and proliferation and promoted the osteogenic differentiation of rabbit adipose-derived stem cells (ADSCs). Successful healing of femoral bone defect was proved by injection of the ADSCs-seeded Sr10-HA-PBLG microcarriers in a rabbit model.

Tracing of aerosol sources in an urban environment using chemical, Sr isotope, and mineralogical characterization.

PubMed

Duarte, Regina M B O; Matos, João T V; Paula, Andreia S; Lopes, Sónia P; Ribeiro, Sara; Santos, José Francisco; Patinha, Carla; da Silva, Eduardo Ferreira; Soares, Rosário; Duarte, Armando C

2017-04-01

In the framework of two national research projects (ORGANOSOL and CN-linkAIR), fine particulate matter (PM 2.5 ) was sampled for 17 months at an urban location in the Western European Coast. The PM 2.5 samples were analyzed for organic carbon (OC), water-soluble organic carbon (WSOC), elemental carbon (EC), major water-soluble inorganic ions, mineralogical, and for the first time in this region, strontium isotope ( 87 Sr/ 86 Sr) composition. Organic matter dominates the identifiable urban PM 2.5 mass, followed by secondary inorganic aerosols. The acquired data resulted also in a seasonal overview of the carbonaceous and inorganic aerosol composition, with an important contribution from primary biomass burning and secondary formation processes in colder and warmer periods, respectively. The fossil-related primary EC seems to be continually present throughout the sampling period. The 87 Sr/ 86 Sr ratios were measured on both the labile and residual PM 2.5 fractions as well as on the bulk PM 2.5 samples. Regardless of the air mass origin, the residual fractions are more radiogenic (representative of a natural crustal dust source) than the labile fractions, whose 87 Sr/ 86 Sr ratios are comparable to that of seawater. The 87 Sr/ 86 Sr ratios and the mineralogical composition data further suggest that sea salt and mineral dust are important primary natural sources of fine aerosols throughout the sampling period.

WHAEM: PROGRAM DOCUMENTATION FOR THE WELLHEAD ANALYTIC ELEMENT MODEL (EPA/600/SR-94/210)

EPA Science Inventory

A new computer program has been developed to determine time-of-travel capture zones in relatively simple geohydrological settings. The WhAEM package contains an analytic element model that uses superposition of (many) closed form analytical solutions to generate a groundwater flo...

Lu-Hf, in-situ Sr and Pb isotope and trace element systematics for mantle eclogites from the Diavik diamond mine: Evidence for Paleoproterozoic subduction beneath the Slave craton, Canada

NASA Astrophysics Data System (ADS)

Schmidberger, Stefanie S.; Simonetti, Antonio; Heaman, Larry M.; Creaser, Robert A.; Whiteford, Sean

2007-02-01

Lu-Hf, Sm-Nd and in-situ clinopyroxene Sr and Pb isotope systematics, and mineral major and in-situ trace element compositions were obtained for a suite of non-diamond and diamond-bearing eclogites from the Diavik kimberlites (A154; 55 Ma old), Slave craton (Canada). Temperature estimates of last equilibration in the lithosphere for the non-diamond-bearing Diavik eclogites define two groups; low-temperature (800-1050 °C) and high-temperature eclogites (1100-1300 °C). Most diamond-eclogites indicate temperatures similar to those of the high-temperature eclogites. Isotopic and major and trace element systematics for the non-diamond- and diamond-bearing eclogites indicate overlapping chemical compositions suggesting similar rock formational histories. Calculated whole rock major and trace element abundances using chemical and modal abundances for constituent minerals exhibit broad similarities with mafic cumulates from ophiolite sequences. Most importantly the calculated whole rock eclogite compositions display positive Sr and Eu anomalies, typically interpreted as the result of plagioclase accumulation in cumulate rocks of oceanic crust sequences. Initial whole rock Hf isotopic values and in-situ Sr isotope data from clinopyroxene grains provide evidence that the eclogites were derived from precursor rocks with depleted mantle isotope characteristics. These combined results support the interpretation that the eclogites from Diavik represent remnants of subducted oceanic crust. Lu-Hf isotope systematics indicate that the oceanic protolith for the eclogites formed in the Paleoproterozoic at ˜ 2.1 Ga, which is in agreement with the in-situ Pb isotope data from clinopyroxene. This result also corroborates the ˜ 2.1 Ga Lu-Hf model ages recorded by mantle zircons from eclogite found within the Jericho kimberlite in the northern Slave Province (˜ 200 km northwest of Diavik). The results from both studies indicate a link between eclogite formation and Paleoproterozoic subduction of oceanic lithosphere along the present-day western margin of the Archean Slave craton.

Transformation of Strontium during formation of biogenic calcium carbonate

NASA Astrophysics Data System (ADS)

Ohnuki, T.; Kozai, N.; Sakamoto, F.; Yamashita, M.; Horiieke, T.; Utsunomiya, S.

2016-12-01

Some amounts of radionuclides contaminated water containing 90Sr generated in the Fukushima Daiichi Nuclear Power Plant were leaked to sea water in the port. One of the possible method to eliminate 90Sr is co-precipitated with biogenic carbonates minerals (CCM). Specific bacteria are known to form biogenic CCM in groundwater. In the present study, we have screened specific bacterium to form CCM in saline water, and studied transformation of Sr during biogenic CCM. A marine microbe of strain TK2d, which is screened from Tokyo bay to form CCM in saline solution, was grown in the medium solution contained urea and Sr. The concentratuion of Sr2+ in the solution was monitored by ICP-OES (ICP-OES; 720 Agilent Technologies, Inc., USA) during the formation of biogenic CCM. The precipitates were analyzed by SEM, TEM, and XAFS. When 1.0 mM Sr was dissolved in the medium solution, the concentration of Sr decreased up to 0.02 mM within 10 days, indicating that most of Sr in the solution was eliminated within 10 days. SEM and TEM analyses showed that needle shaped CCM containing Ca and Sr were formed. The CCM was not single crystalline, but poly-crystalline of calcite and aragonite. The elemental mapping showed that Sr was present at the same position of Ca, indicating that Sr was coprecipitated with Ca. The XANES analysis of Sr in the precipitates showed that the XANES spectrum was not the same as that of Sr coprecipitated with an abiotic Ca carbonates. Linear combination fitting of XANES spectra by those of SrCl2 and SrCO3 showed that both Sr2+ and SrCO3 were present in CCM. Longer contact time resulted in higher content of SrCO3, indicating that Sr was incorporated gradually with time into CCM structure. Thus, Sr was changed its chemical species from adsorbed one to the incorporated one in biogenic CCM in saline solution. This work was partially supported by a research grant from the Japan Science and Technology Agency, Japan (research grant No. 260502).

Stability of the 1144 phase in iron pnictides

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

Song, B. Q.; Nguyen, Manh Cuong; Wang, C. Z.

A series of iron arsenides (e.g., CaRbFe 4As 4, SrCsFe 4As 4) have been discovered recently, and have provoked a rise in superconductor searches in a different phase, known as the 1144 phase. For the presence of various chemical substitutions, it is believed that more 1144 compounds remain to be discovered. Here in this work, we perform general model analysis as well as scenario calculation on a basis of density functional theory to investigate phase stability in a variety of compounds. We predict that the 1144-type phase could be stabilized in EuKFe 4As 4, EuRbFe 4As 4, EuCsFe 4As 4,more » CaCsFe 4P 4, SrCsFe 4P 4, BaCsFe 4P 4, InCaFe 4As 4, InSrFe 4As 4, etc. Remarkably, it involves rare earths, trivalence elements (e.g., indium) and iron phosphides, which greatly expands the range of its existence and suggests a promising prospect for experimental synthesis. In addition, we find that the formation of many random doping compounds (e.g., Ba 0.5Cs 0.5Fe 2As 2, Ba 0.5 Rb 0.5Fe 2As 2) is driven by entropy and could be annealed to a 1144-type phase. Eventually, we plot a phase diagram about two structural factors Δa and Δc, giving a bird's-eye view of stability of various 1144 compounds.« less

Stability of the 1144 phase in iron pnictides

DOE PAGES

Song, B. Q.; Nguyen, Manh Cuong; Wang, C. Z.; ...

2018-03-14

A series of iron arsenides (e.g., CaRbFe 4As 4, SrCsFe 4As 4) have been discovered recently, and have provoked a rise in superconductor searches in a different phase, known as the 1144 phase. For the presence of various chemical substitutions, it is believed that more 1144 compounds remain to be discovered. Here in this work, we perform general model analysis as well as scenario calculation on a basis of density functional theory to investigate phase stability in a variety of compounds. We predict that the 1144-type phase could be stabilized in EuKFe 4As 4, EuRbFe 4As 4, EuCsFe 4As 4,more » CaCsFe 4P 4, SrCsFe 4P 4, BaCsFe 4P 4, InCaFe 4As 4, InSrFe 4As 4, etc. Remarkably, it involves rare earths, trivalence elements (e.g., indium) and iron phosphides, which greatly expands the range of its existence and suggests a promising prospect for experimental synthesis. In addition, we find that the formation of many random doping compounds (e.g., Ba 0.5Cs 0.5Fe 2As 2, Ba 0.5 Rb 0.5Fe 2As 2) is driven by entropy and could be annealed to a 1144-type phase. Eventually, we plot a phase diagram about two structural factors Δa and Δc, giving a bird's-eye view of stability of various 1144 compounds.« less

Stability of the 1144 phase in iron pnictides

NASA Astrophysics Data System (ADS)

Song, B. Q.; Nguyen, Manh Cuong; Wang, C. Z.; Ho, K. M.

2018-03-01

A series of iron arsenides (e.g., CaRbFe4As4 , SrCsFe4As4 ) have been discovered recently, and have provoked a rise in superconductor searches in a different phase, known as the 1144 phase. For the presence of various chemical substitutions, it is believed that more 1144 compounds remain to be discovered. In this work, we perform general model analysis as well as scenario calculation on a basis of density functional theory to investigate phase stability in a variety of compounds. We predict that the 1144-type phase could be stabilized in EuKFe4As4 , EuRbFe4As4 , EuCsFe4As4 , CaCsFe4P4 , SrCsFe4P4 , BaCsFe4P4 , InCaFe4As4 , InSrFe4As4 , etc. Remarkably, it involves rare earths, trivalence elements (e.g., indium) and iron phosphides, which greatly expands the range of its existence and suggests a promising prospect for experimental synthesis. In addition, we find that the formation of many random doping compounds (e.g., Ba0.5Cs0.5Fe2As2 , Ba0.5Rb0.5Fe2As2 ) is driven by entropy and could be annealed to a 1144-type phase. Eventually, we plot a phase diagram about two structural factors Δ a and Δ c , giving a bird's-eye view of stability of various 1144 compounds.

Bone integration capability of a series of strontium-containing hydroxyapatite coatings formed by micro-arc oxidation.

PubMed

Yan, Jun; Sun, Ji-Feng; Chu, Paul K; Han, Yong; Zhang, Yu-Mei

2013-09-01

Strontium-containing hydroxyapatites (Sr-HA) combine the desirable bone regenerative properties of hydroxyapatites (HA) with anabolic and anti-catabolic effects of strontium cations. In the present work, a series of Sr(y)HA [Sr(y)Ca(10-y)(PO4)6(OH)2; y = 0, 0.5, 1, 2] coatings on titanium are produced by micro-arc oxidation (MAO), and the effects of the in vivo osseointegration ability of the coatings are investigated by using a rabbit model. All samples are subjected to biomechanical, surface elemental, micro-CT and histological analysis after 4 and 12 weeks of healing. The obtained results show that the MAO-formed coatings exhibit a microporous network structure composed of Sr(y)HA/Sr(y)HA-Sr(x)Ca(1-x)TiO3/Sr(x)Ca(1-x)TiO3-TiO2 multilayers, in which the outer Sr(y)HA and intermediate Sr(y)HA-Sr(x)Ca(1-x)TiO3 layers have a nanocrystalline structure. All Sr-HA coated implants induce marked improvements in the behavior of bone formation, quantity and quality of bone tissue around the implants than the control HA implant and in particular, the 20%Sr-HA coating promotes early bone formation as identified by polyfluorochrome sequential labeling. The bone-to-implant contact is increased by 46% (p < 0.05) and the pull-out strength is increased by 103% over the HA group (p < 0.01). Extensive areas of mineralized tissue densely deposit on the 20%Sr-HA coating after biomechanical testing, and the greatest improvement of bone microarchitecture are observed around the 20%Sr-HA implant. The identified biological parameters successfully demonstrate the osteoconductivity of 20%Sr-HA surfaces, which results not only in an acceleration but also an improvement of bone-implant integration. The study demonstrates the immense potential of 20%Sr-HA coatings in dental and orthopedic applications. Copyright © 2012 Wiley Periodicals, Inc.

Use of strontium isotopes to identify buried water main leakage into groundwater in a highly urbanized coastal area.

PubMed

Leung, Chi-Man; Jiao, Jiu Jimmy

2006-11-01

Previous studies indicate that the local aquifer systems in the Mid-Levels, a highly urbanized coastal area in Hong Kong, have commonly been affected by leakage from water mains. The identification of leakage locations was done by conventional water quality parameters including major and trace elements. However, these parameters may lead to ambiguous results and fail to identify leakage locations especially where the leakage is from drinking water mains because the chemical composition of drinking water is similar to that of natural groundwater. In this study, natural groundwater, seepage in the developed spaces, leakage from water mains, and parent aquifer materials were measured for strontium isotope (87Sr/86Sr) compositions to explore the feasibility of using these ratios to better constrain the seepage sources. The results show that the 87Sr/86Sr ratios of natural groundwater and leakage from water mains are distinctly different and thus, they can provide additional information on the sources of seepage in developed spaces. A classification system based on the aqueous 87Sr/86Sr ratio is proposed for seepage source identification.

Enhancing Self-Practice/Self-Reflection (SP/SR) approach to cognitive behaviour training through the use of reflective blogs.

PubMed

Farrand, Paul; Perry, Jon; Linsley, Sue

2010-07-01

Self-Practice/Self-Reflection (SP/SR) is increasingly beginning to feature as a central component of CBT training programmes (Bennett-Levy et al., 2001). Programmes including a reflective element, however, are not unproblematic and it has been documented that simply setting time aside for reflection does not necessarily result in trainees using such time to reflect. Such limitations may be overcome by including a requirement to post reflections on reflective blogs. To examine the effect that a requirement to contribute to a reflective blog had upon a SP/SR approach to CBT training. A focus group methodology was adopted with data analyzed using a general inductive qualitative approach. The requirement to use blogs to reflect upon the self-practice of CBT techniques enhanced SP/SR, established a learning community, and improved course supervision, although some technical difficulties arose. Consideration should be given towards using reflective blogs to support a SP/SR approach to CBT training. Benefits afforded by the use of reflective blogs further establish SP/SR as a valid and flexible training approach.

Geochemical variability of the Yucatan basement: Constraints from crystalline clasts in Chicxulub impactites

NASA Astrophysics Data System (ADS)

Kettrup, B.; Deutsch, A.

2003-07-01

The 65 Ma old Chicxulub impact structure with a diameter of about 180 km is again in the focus of the geosciences because of the recently commenced drilling of the scientific well Yaxcopoil- 1. Chicxulub is buried beneath thick post-impact sediments, yet samples of basement lithologies in the drill cores provide a unique insight into age and composition of the crust beneath Yucatan. This study presents major element, Sr, and Nd isotope data for Chicxulub impact melt lithologies and clasts of basement lithologies in impact breccias from the PEMEX drill cores C-1 and Y-6, as well as data for ejecta material from the K/T boundaries at La Lajilla, Mexico, and Furlo, Italy. The impact melt lithologies have an andesitic composition with significantly varying contents of Al, Ca, and alkali elements. Their present day 87Sr/86Sr ratios cluster at about 0.7085, and 143Nd/144Nd ratios range from 0.5123 to 0.5125. Compared to the melt lithologies that stayed inside the crater, data for ejecta material show larger variations. The 87Sr/86Sr ratios range from 0.7081 for chloritized spherules from La Lajilla to 0.7151 for sanidine spherules from Furlo. The 143Nd/144Nd ratio is 0.5126 for La Lajilla and 0.5120 for the Furlo spherules. In an tCHUR(Nd)-tUR(Sr) diagram, the melt lithologies plot in a field delimited by Cretaceous platform sediments, various felsic lithic clasts and a newly found mafic fragment from a suevite. Granite, gneiss, and amphibolite have been identified among the fragments from crystalline basement gneiss. Their 87Sr/86Sr ratios range from 0.7084 to 0.7141, and their 143Nd/144Nd ratios range from 0.5121 to 0.5126. The TNdDM model ages vary from 0.7 to 1.4 Ga, pointing to different source terranes for these rocks. This leads us to believe that the geological evolution and the lithological composition of the Yucatàn basement is probably more complex than generally assumed, and Gondwanan as well as Laurentian crust may be present in the Yucatàn basement.

Use of Quantity Indicators for Forecasting of Biogeochemical Behavior Sr-90 and Cs-137 in the Conditions of the Combined Pollution of Soils

NASA Astrophysics Data System (ADS)

Lavrentyeva, G. V.; Geshel, I. V.

2012-04-01

From huge number of the radionuclides generated by anthropogenous activity the major value the group of biologically active radionuclides has. First of all, it Sr-90 and Cs-137 which play an important role in various radiological situations. In researches on studying of laws of behavior in environment Sr -90 and Cs-137 the basic attention was given to studying of influence of their chemical analogs Ca and K, instead of stable isotopes Sr and Cs. However, even low concentration of stable isotopes Sr and Cs in soil can influence on biogeochemical behavior of radionuclides. Objects of research: dernovo-podsolic soil, summer barley of grade, stable and radioactive isotopes Sr, Cs. Schemes of experiments provided entering of 8 doses stable Cs and Sr in the range from 0 to 500-750 mg/kg of air-dry weight of soil and 50 kBq of radionuclides on each frequency. Absorption of radionuclides by plants will be defined by two parametres of transport. The first - factor of transition (TF), which characterises level of regulation of process of carrying over of a radionuclide from soil in plants and depends on distribution of an element between the firm and liquid phase, distribution defined in the factor (Kd). The second parametre - factor of concentrating (CF) which characterises biological level of regulation of this process. The increase in quantity of stable Sr in soil leads to an active desorption Sr-90 in a soil solution on all frequency. Kd of Cs-137 on the general background of which decrease in values some increase in factor in the range of 120-225 mg of Cs/kg of soil is observed. Received Kd of radionuclides will well be co-ordinated with the revealed functional dependences between concentration Cs and Sr in soil and specific activity Cs-137 and Sr-90 in a soil solution. Comparison CF of two radionuclides shows that plants absorb Sr-90 from a soil solution actively, than Cs-137. Thus values CF of Sr-90 in the investigated interval of concentration of a stable isotope are in inverse relationship from the element maintenance in a soil solution in all investigated interval of the maintenance of the isotope carrier whereas change similar the indicator for Cs-137 has more difficult dependence. The revealed laws of change of CF studied radionuclides prove to be true the received dependences of accumulation Sr-90 and Cs-137 in barley from specific activity of radionuclides in a soil solution. Values of TF of Sr-90 are in direct dependence on level of the maintenance stable Sr, below similar indicators for Cs-137 in all interval of change of concentration of stable isotopes. It finds reflection in the analysis of functional dependences between concentration of radionuclides in plants and soil. The received values of studied factors completely reflect change of specific activity of radionuclides in a soil solution and their biological availability depending on concentration of their stable isotopes that confirms use possibility in the prognostic purposes of these indicators.

Calibration of a conodont apatite-based Ordovician 87Sr/86Sr curve to biostratigraphy and geochronology: Implications for stratigraphic resolution

USGS Publications Warehouse

Saltzman, M. R.; Edwards, C. T.; Leslie, S. A.; Dwyer, Gary S.; Bauer, J. A.; Repetski, John E.; Harris, A. G.; Bergstrom, S. M.

2014-01-01

The Ordovician 87Sr/86Sr isotope seawater curve is well established and shows a decreasing trend until the mid-Katian. However, uncertainties in calibration of this curve to biostratigraphy and geochronology have made it difficult to determine how the rates of 87Sr/86Sr decrease may have varied, which has implications for both the stratigraphic resolution possible using Sr isotope stratigraphy and efforts to model the effects of Ordovician geologic events. We measured 87Sr/86Sr in conodont apatite in North American Ordovician sections that are well studied for conodont biostratigraphy, primarily in Nevada, Oklahoma, the Appalachian region, and Ohio Valley. Our results indicate that conodont apatite may provide an accurate medium for Sr isotope stratigraphy and strengthen previous reports that point toward a significant increase in the rate of fall in seawater 87Sr/86Sr during the Middle Ordovician Darriwilian Stage. Our 87Sr/86Sr results suggest that Sr isotope stratigraphy will be most useful as a high-resolution tool for global correlation in the mid-Darriwilian to mid-Sandbian, when the maximum rate of fall in 87Sr/86Sr is estimated at ∼5.0–10.0 × 10–5 per m.y. Variable preservation of conodont elements limits the precision for individual stratigraphic horizons. Replicate conodont analyses from the same sample differ by an average of ∼4.0 × 10–5 (the 2σ standard deviation is 6.2 × 10–5), which in the best case scenario allows for subdivision of Ordovician time intervals characterized by the highest rates of fall in 87Sr/86Sr at a maximum resolution of ∼0.5–1.0 m.y. Links between the increased rate of fall in 87Sr/86Sr beginning in the mid-late Darriwilian (Phragmodus polonicus to Pygodus serra conodont zones) and geologic events continue to be investigated, but the coincidence with a long-term rise in sea level (Sauk-Tippecanoe megasequence boundary) and tectonic events (Taconic orogeny) in North America provides a plausible explanation for the changing magnitude and87Sr/86Sr of the riverine Sr flux to the oceans.

X-ray STM: Nanoscale elemental analysis & Observation of atomic track.

PubMed

Saito, Akira; Furudate, Y; Kusui, Y; Saito, T; Akai-Kasaya, M; Tanaka, Y; Tamasaku, K; Kohmura, Y; Ishikawa, T; Kuwahara, Y; Aono, M

2014-11-01

Scanning tunneling microscopy (STM) combined with brilliant X-rays from synchrotron radiation (SR) can provide various possibilities of original and important applications, such as the elemental analysis on solid surfaces at an atomic scale. The principle of the elemental analysis is based on the inner-shell excitation of an element-specific energy level "under STM observation". A key to obtain an atomic locality is to extract the element-specific modulation of the local tunneling current (not emission that can damage the spatial resolution), which is derived from the inner-shell excitation [1]. On this purpose, we developed a special SR-STM system and smart tip. To surmount a tiny core-excitation efficiency by hard X-rays, we focused two-dimensionally an incident beam having the highest photon density at the SPring-8.After successes in the elemental analyses by SR-STM [1,2] on a semiconductor hetero-interface (Ge on Si) and metal-semiconductor interface (Cu on Ge), we succeeded in obtaining the elemental contrast between Co nano-islands and Au substrate. The results on the metallic substrate suggest the generality of the method and give some important implications on the principle of contrast. For all cases of three samples, the spatial resolution of the analysis was estimated to be ∼1 nm or less, and it is worth noting that the measured surface domains had a deposition thickness of less than one atomic layer (Fig. 1, left and center).jmicro;63/suppl_1/i14-a/DFU045F1F1DFU045F1Fig. 1.(left) Topographic image and (center) beam-induced tip current image of Ge(111)-Cu (-2V, 0.2 nA). (right) X-ray- induced atomic motion tracks on Ge(111) that were newly imaged by the Xray-STM. On the other hand, we found that the "X-ray induced atomic motion" can be observed directly with atomic scale using the SR-STM system effectively under the incident photon density of ∼2 x10(15) photon/sec/mm(2) [3]. SR-STM visualized successfully the track of the atomic motion (Fig. 1, right), which enabled the further analysis on the mechanism of the atomic motion. It is worth comparing our results with past conventional thermal STM observations on the same surface [4], where the atomic motion was found to occur in the 2-dimensional domain. However, our results show the atomic track having a local chain distribution [3].The above mentioned results will allow us to investigate the chemical analysis and control of the local reaction with the spatial resolution of STM, giving hope of wide applications. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The size distribution and origin of elements bound to ambient particles: a case study of a Polish urban area.

PubMed

Rogula-Kozłowska, Wioletta; Majewski, Grzegorz; Czechowski, Piotr Oskar

2015-05-01

Ambient particulate matter (PM) was sampled in Zabrze (southern Poland) in the heating period of 2009. It was investigated for distribution of its mass and of the masses of its 18 component elements (S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Ge, As, Br, Sr, Cd, Sb, Ba, and Pb) among 13 PM size fractions. In the paper, the distribution modality of and the correlations between the ambient concentrations of these elements are discussed and interpreted in terms of the source apportionment of PM emissions. By weight, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Ge, As, Br, Sr, Cd, Sb, Ba, and Pb were 10% of coarse and 9% of ultrafine particles. The collective mass of these elements was no more than 3.5 % of the mass of the particles with the aerodynamic diameter D p between 0.4 and 1.0 μm (PM₀.₄₋₁), whose ambient mass concentration was the highest. The PM mass size distribution for the sampling period is bimodal; it has the accumulation and coarse modes. The coarse particles were probably of the mineral/soil origin (characteristic elements: Ca, Fe, Sr, and Ba), being re-suspended polluted soil or road dust (characteristic elements: Ca, Fe, Sr, Ba, S, K, Cr, Cu, Zn, Br, Sb, Pb). The maxima of the density functions (modes) of the concentration distributions with respect to particle size of PM-bound S, Cl, K, Cu, Zn, Ge, Br, Cd, Sb, and Pb within the D p interval from 0.108 to 1.6 μm (accumulation PM particles) indicate the emissions from furnaces and road traffic. The distributions of PM-bound As, Mn, Ba, and Sr concentrations have their modes within D p ≤ 0.108 μm (nucleation PM particles), indicating the emissions from high-temperature processes (industrial sources or car engines). In this work, principal component analysis (PCA) is applied separately to each of the 13 fraction-related sets of the concentrations of the 18 PM-bound elements, and further, the fractions are grouped by their origin using cluster analysis (CA) applied to the 13 fraction-related first principal components (PC1). Four distinct groups of the PM fractions are identified: (PM₁.₆₋₂.₅, PM₂.₅₋₄.₄,), (PM₀.₀₃₋₀.₀₆, PM₀.₁₀₈₋₀.₁₇), (PM₀.₀₆₋₀.₁₀₈, PM₀.₁₇₋₀.₂₆, PM₀.₂₆₋₀.₄, PM₀.₄₋₀.₆₅, PM₀.₆₅₋₁, PM₁₋₁.₆), and (PM₄.₄₋₆.₈, PM₆.₈₋₁₀, PM>₁₀). The PM sources attributed to these groups by using PCA followed by CA are roughly the same as the sources from the apportionment done by analyzing the modality of the mass size distributions.

The Debate on the Prospective Interaction between SWIR 46°-52°E and Crozet hotspot: Constrain from the Geochemical Characteristics and Helium isotopes of MORBs from Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Yu, X.; Dick, H. J. B.; Chu, F.; Li, X.; Tang, L.

2017-12-01

The Southwest Indian Ridge with obvious mantle heterogeneity is often attributed to the influence of nearby hotspots. The Dragon Flag Supersegment between 46°E and 52°E on Marion Rise has thicker crust, shallower axial depth, and lower mantle Bouguer anomaly, which indicates ridge-hotspot interaction. However, the great distance between Crozet hotspot and the supersegment (about 1,000km) and the controversial geochemical data are both against the prospective ridge-hotspot interaction. Here we compiled major element, trace element, Sr-Nd-Pb and He isotopic data of new samples from the supersegment. The mantle source, partial melting process as well as the crystallization history of these basalts are further constrained based on the synthetic analysis of the dataset. Most basalts from the supersegment require 0 to 30% olivine and plagioclase fractionation to account for their present composition, whereas the crystallization of clinopyroxene appears to be rather limited. The parental magmas of the supersegment are distinctive from east to west. Most samples from the Eastern Group can be modeled as the product of 10% partial melting of a DMM-like source, while some extremely depleted samples from the central valley may require two stages of partial melting, i.e. ancient melting of DMM-like source, followed by recent remelting of the residues. The Western Group may be resulted from lower degree of partial melting (5-10%), or a previously less depleted mantle source. The Eastern Group is favor of the involvement of Crozet hotspot in terms of Pb isotope and helium isotope signatures, but the trace element and Sr-Nd isotopes are not supportive for this interaction. The especially high 206Pb/204Pb for some of the samples from the Eastern Group, similar to the Crozet hotspot, requires the sporadical entrainment of blobs of relatively enriched source material, like the Crozet component. The Crozet hotspot is distinctive in its Sr-Nd-Pb-He isotopes among different islands, thus it is more complicate to address the issue of ridge-hotspot interaction. We suggest that the prospective Crozet-SWIR interaction is possible and can explain most of the geological and geochemical signatures.

Sr heterogeneity in textit{Arctica islandica} shells and the potential use of Sr/Ca ratios as paleotemperature proxies

NASA Astrophysics Data System (ADS)

Radermacher, Pascal; Schöne, Bernd R.; Nunn, Elizabeth V.; Zengjie, Zhang

2010-05-01

Quantifiable paleotemperature data can help to verify predictions made by numerical climate models. Traditionally, paleotemperature estimates are based on δ18O values of biogenic hard parts. However, oxygen isotope values not only reflect changes in ambient temperature, but also changes in δ18Owater, i.e. driven by freshwater influx, evaporation etc. Information regarding the δ18Owater value of past environments is limited for the geological past. The validity of published δ18O paleotemperature data can be tested using element-to-calcium ratios of bivalve shells such as the long-lived ocean quahog, Arctica islandica. Preliminary investigations suggest that Sr/Ca ratios of this species may provide more reliable paleotemperature data. However, contemporaneously deposited shell portions within the outer shell layer demonstrate at least a 30% variability in the Sr/Ca value. This study presents Sr/Ca ratios measured by ICP-OES wet-chemical analyses. Significantly different distributions of Sr/Ca ratios were recorded from the shell surface (over 1330 ppm), through the interior (850 ppm) and to the inner shell surface (1860 ppm). Furthermore, this study showed that different shell crystal fabrics incorporate different amounts of Sr into the CaCO3 lattice of the A. islandica shell. Disparate Sr distribution could potentially be explained either by postdepositional diagenetic processes or syndepositional processes during biomineralization (i.e. different amounts of Sr incorporated into the shell). Understanding the mechanism of the observed Sr heterogeneity is essential if Sr/Ca ratios are to be used confidently in paleotemperature reconstructions.

Spatial and temporal variations of Rb/Sr ratios of the bulk surface sediments in Lake Qinghai

PubMed Central

2010-01-01

The Rb/Sr ratios of lake sediments have been suggested as indicators of weathering intensity by increasing work. However, the geochemistry of Rb/Sr ratios of lake sediments is variable between different lakes. In this study, we investigated the spatial and temporal patterns of Rb/Sr ratios, as well as those of other major elements in surface sediments of Lake Qinghai. We find that the spatial pattern of Rb/Sr ratios of the bulk sediments correlates well with that of the mass accumulation rate, and those of the terrigenous fractions, e.g., SiO2, Ti, and Fe. The temporal variations of Rb/Sr ratios also synchronize with those of SiO2, Ti, and Fe of each individual core. These suggest that Rb/Sr ratios of the surface sediments are closely related to terrigenous input from the catchment. Two out of eight cores show similar trends between Rb/Sr ratios and precipitation indices on decadal scales; however, the other cores do not show such relationship. The result of this study suggests that physical weathering and chemical weathering in Lake Qinghai catchment have opposite influence on Rb/Sr ratios of the bulk sediments, and they compete in dominating the Rb/Sr ratios of lake sediments on different spatial and temporal scales. Therefore, it is necessary to study the geochemistry of Rb/Sr ratio of lake sediments (especially that on short term timescales) particularly before it is used as an indicator of weathering intensity of the catchment. PMID:20615264

Determination of (87)Sr/(86)Sr and δ(88/86)Sr ratios in plant materials using MC-ICP-MS.

PubMed

Liu, Hou-Chun; Chung, Chuan-Hsiung; You, Chen-Feng; Chiang, Yi-Hsuan

2016-01-01

A protocol for highly accurate and precise determination of Sr isotope ratios in plant materials, (87)Sr/(86)Sr and δ (88/86)Sr, by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) is presented in this study. An Eichrom Sr resin was used for matrix separation and an improved Zr empirical external normalization coupled with standard-sample bracketing method (Zr EEN-SSB) was applied to mass bias correction during Sr isotope MC-ICP-MS measurements. Potential influences of matrix elements, and polyatomic and isobaric interferences on the Sr isotopic determination were further evaluated using NIST SRM 987 Sr isotopic standard spiked with various amount of Ca, Mg, and Rb contents. Concentrations of Ca and Mg lower than 30 ng g(-1) or Rb < 2 ng g(-1) in 150 ng g(-1) Sr analyte were estimated to have only a minor effect on Sr isotope ratios determination. On the other hand, intensity differences between sample and standards (IntSample/IntStandards) represented a large δ (88/86)Sr deviation of <0.9 or >1.3, reflecting the significance of intensity bias attributed to different mass bias behavior. An apple leaf material, NIST SRM 1515, was adopted as the plant material for overall evaluation of sample digestion, matrix separation, and potential spectral interferences on the measurements of Sr isotope ratios. Our results suggest that the partially remaining organic compounds in the incomplete digestion would have a significant bias on the extraction chromatography procedure, resulting in sizable uncertainty in δ (88/86)Sr ratios. Thus, complete digestion of the organic-enriched materials is of great importance for efficiency assurance in matrix separation. Extraction chromatography works well for the total digested samples, where Ca, Mg, and Rb were efficiently removed. The obtained average (87)Sr/(86)Sr and δ (88/86)Sr values for the NIST SRM 1515 apple leaves are 0.71398 ± 0.00004 and 0.23 ± 0.03‰ (2SD, n = 10), respectively.

Scavenger Receptor-A deficiency impairs immune response of microglia and astrocytes potentiating Alzheimer's disease pathophysiology.

PubMed

Cornejo, Francisca; Vruwink, Marianne; Metz, Claudia; Muñoz, Paola; Salgado, Nicole; Poblete, Joaquín; Andrés, María Estela; Eugenín, Jaime; von Bernhardi, Rommy

2018-03-01

Late onset Alzheimer disease's (LOAD) main risk factor is aging. Although it is not well known which age-related factors are involved in its development, evidence points out to the involvement of an impaired amyloid-β (Aβ) clearance in the aged brain among possible causes. Glial cells are the main scavengers of the brain, where Scavenger Receptor class A (SR-A) emerges as a relevant player in AD because of its participation in Aβ uptake and in the modulation of glial cell inflammatory response. Here, we show that SR-A expression is reduced in the hippocampus of aged animals and APP/PS1 mice. Given that Aβ deposition increases in the aging brain, we generated a triple transgenic mouse, which accumulates Aβ and is knockout for SR-A (APP/PS1/SR-A -/- ) to evaluate Aβ accumulation and the inflammatory outcome of SR-A depletion in the aged brain. The lifespan of APP/PS1/SR-A -/- mice was greatly reduced, accompanied by a 3-fold increase in plasmatic pro-inflammatory cytokines, and reduced performance in a working memory behavioral assessment. Microglia and astrocytes lacking SR-A displayed impaired oxidative response and nitric oxide production, produced up to 7-fold more pro-inflammatory cytokines and showed a 12-fold reduction in anti-inflammatory cytokines release, with conspicuous changes in lipopolysaccharide-induced glial activation. Isolated microglia from young and adult mice lacking SR-A showed a 50% reduction in phagocytic activity. Our results indicate that reduced expression of SR-A can deregulate glial inflammatory response and potentiate Aβ accumulation, two mechanisms that could contribute to AD progression. Copyright © 2017 Elsevier Inc. All rights reserved.

Linking Barbados Mineral Dust Aerosols to North African Sources Using Elemental Composition and Radiogenic Sr, Nd, and Pb Isotope Signatures

NASA Astrophysics Data System (ADS)

Bozlaker, Ayse; Prospero, Joseph M.; Price, Jim; Chellam, Shankararaman

2018-01-01

Large quantities of African dust are carried across the Atlantic to the Caribbean Basin and southern United States where it plays an important role in the biogeochemistry of soils and waters and in air quality. Dusts' elemental and isotopic composition was comprehensively characterized in Barbados during the summers of 2013 and 2014, the season of maximum dust transport. Although total suspended insoluble particulate matter (TSIP) mass concentrations varied significantly daily and between the two summers, the abundances (μg element/g TSIP) of 50 elements during "high-dust days" (HDD) were similar. Aerosols were regularly enriched in Na, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, and W relative to the upper continental crust. Enrichment of these elements, many of which are anthropogenically emitted, was significantly reduced during HDD, attributed to mixing and dilution with desert dust over source regions. Generally, Ti/Al, Si/Al, Ca/Al, Ti/Fe, Si/Fe, and Ca/Fe ratios during HDD differed from their respective values in hypothesized North African source regions. Nd isotope composition was relatively invariant for "low-dust days" (LDD) and HDD. In contrast, HDD-aerosols were more radiogenic exhibiting higher 87Sr/86Sr, 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios compared to LDD. Generally, Barbados aerosols' composition ranged within narrow limits and was much more homogeneous than that of hypothesized African source soils. Our results suggest that summertime Barbados aerosols are dominated by a mixture of particles originating from sources in the Sahara-Sahel regions. The Bodélé Depression, long suspected as a major source, appears to be an insignificant contributor of summertime western Atlantic dust.

Inorganic profile of some Brazilian medicinal plants obtained from ethanolic extract and ''in natura'' samples

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

Ferreira, M.O.M.; de Sousa, P.T.; Salvador, V.L.R.

The Anadenathera macrocarpa, Schinus molle, Hymenaea courbaril, Cariniana legalis, Solidago microglossa and Stryphnodendron barbatiman, were collected ''in natura'' samples (leaves, flowers, barks and seeds) from different commercial suppliers. The pharmaco-active compounds in ethanolic extracts had been made by the Mato Grosso Federal University (UFMT). The energy-dispersive x-ray fluorescence (ED-XRF) spectrometry was used for the elemental analysis in different parts of the plants and respective ethanolic extracts. The Ca, Cl, Cu, Fe, K, Mg, Mn, Na, Ni, P, Rb, S, Sr and Zn concentrations were determined by the fundamental parameters method. Some specimens showed a similar inorganic profile for ''in natura''more » and ethanolic extract samples and some ones showed a distinct inorganic profile. For example, the Anadenathera macrocarpa showed a similar concentration in Mg, P, Cu, Zn and Rb elements in ''in natura'' and ethanolic extract samples; however very different concentration in Na, S, Cl, K , Ca, Mn, Fe and Sr was observed in distinctive samples. The Solidago microglossa showed the K, Ca, Cl, S, Mg, P and Fe elements as major constituents in both samples, suggesting that the extraction process did not affect in a considerable way the ''in natura'' inorganic composition. The elemental composition of the different parts of the plants (leaves, flowers, barks and seeds) has been also determined. For example, the Schinus molle specimen showed P, K, Cl and Ca elements as major constituents in the seeds, Mg, K and Sr in the barks and Mg, S, Cl and Mn in the leaves, demonstrating a differentiated elementary distribution. These inorganic profiles will contribute to evaluate the quality control of the Brazilian herbaceous trade and also will assist to identify which parts of the medicinal plants has greater therapeutic effect.« less

Using noble gases and 87Sr/86Sr to constrain heat sources and fluid evolution at the Los Azufres Geothermal Field, Mexico

NASA Astrophysics Data System (ADS)

Wen, T.; Pinti, D. L.; Castro, M. C.; Lopez Hernandez, A.; Hall, C. M.; Shouakar-Stash, O.; Sandoval-Medina, F.

2017-12-01

Geothermal wells and hot springs were sampled for noble gases' volume fraction and isotopic measurements and 87Sr/86Sr in the Los Azufres Geothermal Field (LAGF), Mexico, to understand the evolution of fluid circulation following three decades of exploitation and re-injection of used brines. The LAGF, divided into the Southern Production Zone (SPZ) and the Northern Production Zone (NPZ), is hosted in a Miocene to Pliocene andesitic volcanic complex covered by Quaternary rhyolitic-dacitic units. Air contamination corrected 3He/4He ratios (Rc) normalized to the atmospheric ratio (Ra=1.384 x 10-6), show a median value of 6.58 indicating a dominant mantle helium component. Contributions of crustal helium up to 53% and 18% are observed in NPZ and SPZ, respectively. Observations based on Rc/Ra and 87Sr/86Sr ratios points to the mixing of three magmatic sources supplying mantle helium to the LAGF: (1) a pure mantle He (Rc/Ra = 8) and Sr (87Sr/86Sr = 0.7035) source; (2) a pure mantle helium (Rc/Ra = 8) with some radiogenic Sr (87Sr/86Sr = 0.7049) source possibly resulting from Quaternary rhyolitic volcanism; and (3) a fossil mantle He component (Rc/Ra = 3.8) with some radiogenic Sr (87Sr/86Sr = 0.7038), corresponding possibly to the Miocene andesite reservoir. Intrusions within the last 50 kyrs from sources (1) and (2) are likely responsible for the addition of mantle volatiles and heat to the hydrothermal system of Los Azufres. He and Ar isotopes indicate that heat flow is transported by both convection and conduction. Atmospheric noble gas elemental ratios suggest that geothermal wells located closer to the western re-injection zone are beginning to be dominated by re-injection of used brines (injectate). The area affected by boiling in LAGF has further extended to the north and west since the last noble gas sampling campaign in 2009.

Distribution of Minor Elements in Calcite From the Unsaturated Zone at Yucca Mountain, Nevada

NASA Astrophysics Data System (ADS)

Marshall, B. D.; Whelan, J. F.

2001-12-01

Calcite is sporadically distributed in fractures and cavities in the volcanic rocks that form the 500- to 700-m-thick unsaturated zone at Yucca Mountain. Previous work has shown that the calcite precipitated from water moving downward through the unsaturated zone since the volcanic rocks were emplaced approximately 13 Ma. Calcite thus serves as a proxy for the chemistry and amounts of past percolation, two parameters that are important in predictions of the future behavior of the potential radioactive waste repository at Yucca Mountain. Latest calcite, which began forming between approximately 5 and 2 Ma, typically displays fine-scale growth zoning defined by distributions of Mn (inferred from cathodoluminescence), Mg, and Sr. Electron microprobe (EPMA) mapping of outermost calcite reveals Mg growth zoning1 and higher overall concentrations of Mg in late calcite than in older calcite. Micro X-ray fluorescence (micro-XRF) maps were obtained by slow rastering of the samples over a 100-watt X-ray source collimated through a final aperture of 100 μ m. Although the spatial resolution of the micro-XRF mapping is much less than that of EPMA, this technique reveals distributions of some elements to which EPMA is less sensitive. Micro-XRF maps show that Sr is spatially correlated with Mg; Sr concentrations range to 500 μ g/g at the resolution of the 100-μ m collimator. Because both Mg and Sr have similar calcite-water distribution coefficients much less than one, the Mg/Sr in calcite reflects the Mg/Sr of the water that precipitated the calcite. The distribution coefficient for Mn is greater than one and variations in Mn are not correlated with Mg and Sr. Covariation of Mg and Sr in the percolating water may be explained by reactions that affect the rate of uptake of chemical constituents from the overlying rock and soil, and/or evaporation. Late calcite has lower δ 13C values, probably due to a regional change from wetter to drier climate conditions. The higher Mg and Sr concentrations in the late calcite may record lower deposition rates and decreased percolation fluxes due to the drier climate. 1 Wilson, N.S.F., Cline, J.S., and Lundberg, S.A.W., 2000, Paragenesis and chemical composition of secondary mineralization at Yucca Mountain, Nevada, Geol. Soc. Am. Abs. Prog., v. 32, p. A260.

Twentieth century warming of the tropical Atlantic captured by Sr-U paleothermometry

NASA Astrophysics Data System (ADS)

Alpert, Alice E.; Cohen, Anne L.; Oppo, Delia W.; DeCarlo, Thomas M.; Gaetani, Glenn A.; Hernandez-Delgado, Edwin A.; Winter, Amos; Gonneea, Meagan E.

2017-02-01

Coral skeletons are valuable archives of past ocean conditions. However, interpretation of coral paleotemperature records is confounded by uncertainties associated with single-element ratio thermometers, including Sr/Ca. A new approach, Sr-U, uses U/Ca to constrain the influence of Rayleigh fractionation on Sr/Ca. Here we build on the initial Pacific Porites Sr-U calibration to include multiple Atlantic and Pacific coral genera from multiple coral reef locations spanning a temperature range of 23.15-30.12°C. Accounting for the wintertime growth cessation of one Bermuda coral, we show that Sr-U is strongly correlated with the average water temperature at each location (r2 = 0.91, P < 0.001, n = 19). We applied the multispecies spatial calibration between Sr-U and temperature to reconstruct a 96 year long temperature record at Mona Island, Puerto Rico, using a coral not included in the calibration. Average Sr-U derived temperature for the period 1900-1996 is within 0.12°C of the average instrumental temperature at this site and captures the twentieth century warming trend of 0.06°C per decade. Sr-U also captures the timing of multiyear variability but with higher amplitude than implied by the instrumental data. Mean Sr-U temperatures and patterns of multiyear variability were replicated in a second coral in the same grid box. Conversely, Sr/Ca records from the same two corals were inconsistent with each other and failed to capture absolute sea temperatures, timing of multiyear variability, or the twentieth century warming trend. Our results suggest that coral Sr-U paleothermometry is a promising new tool for reconstruction of past ocean temperatures.

Twentieth century warming of the tropical Atlantic captured by Sr-U paleothermometry

USGS Publications Warehouse

Alpert, Alice E.; Cohen, Anne L.; Oppo, Delia W.; DeCarlo, Thomas M.; Gaetani, Glenn A.; Hernandez-Delgado, Edwin A.; Winter, Amos; Gonneea, Meagan

2017-01-01

Coral skeletons are valuable archives of past ocean conditions. However, interpretation of coral paleotemperature records is confounded by uncertainties associated with single-element ratio thermometers, including Sr/Ca. A new approach, Sr-U, uses U/Ca to constrain the influence of Rayleigh fractionation on Sr/Ca. Here we build on the initial Pacific Porites Sr-U calibration to include multiple Atlantic and Pacific coral genera from multiple coral reef locations spanning a temperature range of 23.15–30.12°C. Accounting for the wintertime growth cessation of one Bermuda coral, we show that Sr-U is strongly correlated with the average water temperature at each location (r2 = 0.91, P < 0.001, n = 19). We applied the multispecies spatial calibration between Sr-U and temperature to reconstruct a 96 year long temperature record at Mona Island, Puerto Rico, using a coral not included in the calibration. Average Sr-U derived temperature for the period 1900–1996 is within 0.12°C of the average instrumental temperature at this site and captures the twentieth century warming trend of 0.06°C per decade. Sr-U also captures the timing of multiyear variability but with higher amplitude than implied by the instrumental data. Mean Sr-U temperatures and patterns of multiyear variability were replicated in a second coral in the same grid box. Conversely, Sr/Ca records from the same two corals were inconsistent with each other and failed to capture absolute sea temperatures, timing of multiyear variability, or the twentieth century warming trend. Our results suggest that coral Sr-U paleothermometry is a promising new tool for reconstruction of past ocean temperatures.

Effect of Microstructure on the Radioluminescence and Transparency of Ce-Doped Strontium Hafnate Ceramics

PubMed Central

van Loef, Edgar V.; Wang, Yimin; Miller, Stuart R.; Brecher, Charles; Rhodes, William H.; Baldoni, Gary; Topping, Stephen; Lingertat, Helmut; Sarin, Vinod K.; Shah, Kanai S.

2011-01-01

In this paper we report on the fabrication and characterization of SrHfO3:Ce ceramics. Powders were prepared by solid-state synthesis using metal oxides and carbonates. X-ray diffraction measurements showed that phase-pure SrHfO3 is formed at 1200°C. Inductively coupled plasma spectroscopy confirmed the purity and composition of each batch. SrHfO3 exhibits several phase changes in the solid, but this does not appear to be detrimental to the ceramics. Microprobe experiments showed uniform elemental grain composition, whereas aluminum added as charge compensation for trivalent cerium congregated at grain boundaries and triple points. Radioluminescence spectra revealed that the light yield decreases when the concentration of excess Sr increases. The decrease in the light yield may be related to the change of Ce3+ into Ce4+ ions. For stoichiometric SrHfO3:Ce, the light yield is about four times that of bismuth germanate (BGO), the conventional benchmark, indicating great potential for many scintillator applications. PMID:21339835

Review of the Constellation Level II Safety, Reliability, and Quality Assurance (SR&QA) Requirements Documents during Participation in the Constellation Level II SR&QA Forum

NASA Technical Reports Server (NTRS)

Cameron, Kenneth D.; Gentz, Steven J.; Beil, Robert J.; Minute, Stephen A.; Currie, Nancy J.; Scott, Steven S.; Thomas, Walter B., III; Smiles, Michael D.; Schafer, Charles F.; Null, Cynthia H.;

Thermoelectric properties of the yttrium-doped ceramic oxide SrTiO3

NASA Astrophysics Data System (ADS)

Khan, Tamal Tahsin; Ur, Soon-Chul

2017-01-01

The doping dependence of the thermoelectric figure of merit, ZT, of the ceramic oxide SrTiO3 at high temperature has been studied. In this study, yttrium was used as the doping element. A conventional solid-state reaction method was used for the preparation of Y-doped SrTiO3. The doping level in SrTiO3 was controlled to be in the doping range of 2 - 10 mole%. Almost all the yttrium atoms incorporated into the SrTiO3 provided charge carriers, as was observed by using X-ray diffraction pattern. The relative densities of all the samples varied from 98.53% to 99.45%. The thermoelectric properties, including the electrical conductivity σ, Seebeck coefficient S, thermal conductivity k, and the figure of merit, ZT, were investigated at medium temperatures. The ZT value showed an obvious doping level dependence, in which a value as high as 0.18 is realized at 773 K for a doping of 8 mole%.

MCPIP1-induced autophagy mediates ischemia/reperfusion injury in endothelial cells via HMGB1 and CaSR.

PubMed

Xie, Xiaolong; Zhu, Tiebing; Chen, Lulu; Ding, Shuang; Chu, Han; Wang, Jing; Yao, Honghong; Chao, Jie

2018-01-29

Monocyte chemotactic protein-1-induced protein 1 (MCPIP1) plays a important role in ischemia/reperfusion (I/R) injury. Autophagy is involved in activating endothelial cells in response to I/R. However, researchers have not clearly determined whether MCPIP1 mediates I/R injury in endothelial cells via autophagy, and its downstream mechanism remains unclear. Western blotting analyses and immunocytochemistry were applied to detect protein levels were detected in HUVECs. An in vitro scratch assay was used to detect cell migration. Cells were transfected with siRNAs to knockdown MCPIP1 and high mobility group box 1 (HMGB1) expression. The pharmacological activator of autophagy rapamycin and the specific calcium-sensing receptor (CaSR) inhibitor NPS-2143 were used to confirm the roles of autophagy and CaSR in I/R injury. I/R induced HMGB1 and CaSR expression, which subsequently upreguated the migration and apoptosis of HUVECs and coincided with the increase of autophagy. HMGB1 was involved in cell migration, whereas CaSR specifically participated in I/R-induced HUVEC apoptosis. Based on these findings, I/R-induced MCPIP1 expression regulates the migration and apoptosis of HUVECs via HMGB1 and CaSR, respectively, suggesting a new therapeutic targetof I/R injury.

Volatile, Trace Element and Isotopic Variations of Mafic Arc Volcanic Rocks from Nicaragua and Costa Rica

NASA Astrophysics Data System (ADS)

Hoernle, K.; Sadofsky, S.; Nichols, H.; Portnyagin, M.; van den Bogaard, P.; Alvarado, G.

2003-12-01

Quaternary volcanic rocks from the Central American Volcanic Arc in central Nicaragua and central Costa Rica exhibit major differences in their volatile, trace element and isotopic compositions. Olivine-hosted melt inclusions in Nicaraguan volcanic rocks with high Fo contents (>73) extend to high H2O (up to 5.3%), S (10-6860 ppm) and Cl (490-2340 ppm) contents. The volcanic rocks have high ratios of fluid mobile to fluid immobile elements such as Ba/La (65-122), Ba/Th (484-1304) and U/La (0.08-0.17). Additionally, they have 143Nd/144Nd (0.51300-0.51307) similar to normal mid-ocean-ridge basalts (N-MORB) from the East Pacific Rise (EPR), but 87Sr/86Sr (0.7035-0.7042) ratios are much higher than those found in fresh EPR glasses. Pb isotopic compositions of the samples (e.g. 206Pb/204Pb = 18.5-19.0, 207Pb/204Pb = 15.52-15.58) form an array between EPR basalts and subducted sediments. The volatile, trace element and isotope data are consistent with mixing of fluids highly enriched in fluid-mobile elements from subducted sediments with a N-MORB-type mantle wedge to produce the Nicaraguan volcanic rocks. In contrast, olivine-hosted melt inclusions (Fo >82) in Costa Rican volcanic rocks show a similar range in H2O (up to 5.1%) to Nicaraguan inclusions but overall have lower S (0-1340 ppm) and Cl (10-790 ppm) contents. Costa Rican lavas also have lower Ba/La (7-35), Ba/Th (55-338), U/La (0.02-0.12), 87Sr/86Sr (0.7035-0.7038) and 143Nd/144Nd (0.51292-0.51301) than Nicaraguan lavas, but 87Sr/86Sr and Pb isotope ratios (e.g. 206Pb/204Pb = 19.02-19.32) are more radiogenic than in Nicaragua and than usually found in fresh EPR MORB. Our data are consistent with the presence of Galapagos Hotspot-type components in the source of the central Costa Rican volcanic rocks, derived from the subducting Galapagos Hotspot Track and from Galapagos-type material entering the mantle wedge through a slab tear or window (Abratis and Worner, 2000; Geology). The estimated volume of volcanic rocks erupted in the last 100,000 years (Carr et al., 1990, Contrib. Min. Pet.; in press, AGU Spec. Pub.) are substantially higher in central Costa Rica than in Nicaragua, suggesting greater productivity of melting beneath Costa Rica. Since the flux of hydrous fluids appears to be similar beneath both arc segments, higher melt productivity beneath Costa Rica could reflect the presence of larger volumes of more fertile, hotter Galapagos-type mantle upwelling through a slab tear or window into the Costa Rican mantle wedge.

Elemental mapping of teeth using μSRXRF

NASA Astrophysics Data System (ADS)

Anjos, M. J.; Barroso, R. C.; Pérez, C. A.; Braz, D.; Moreira, S.; Dias, K. R. H. C.; Lopes, R. T.

2004-01-01

Human teeth were analysed by X-ray microfluorescence analysis using synchrotron radiation (μSRXRF). The aim of this work was to study the elemental distribution for Ca, Zn and Sr along the dental regions, enamel, dentine and pulp from patterns of relative fluorescence intensities. The measurements were performed in standard geometry of 45° incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). The results show that Ca distribution is quite constant and it is independent of the tooth type and individuals characteristics. An increase of the Zn concentration was found for the pulp region and for untreated carious areas. Ca and Sr distributions show a similar behavior.

Pb, Sr and Nd isotopic composition and trace element characteristics of coarse airborne particles collected with passive samplers

NASA Astrophysics Data System (ADS)

Hoàng-Hòa, Thi Bich; Stille, Peter; Dietze, Volker; Guéguen, Florence; Perrone, Thierry; Gieré, Reto

2015-09-01

Passive samplers for collection of coarse airborne particulate matter have been installed in and around the coal-mining town of Cam Pha, Quang Ninh Province (Vietnam). Analysis of Pb, Sr, and Nd isotope ratios and of major and trace element distribution patterns in atmospheric particulates collected at three stations allowed for the identification of four important dust components: (1) coal dust from an open-pit mine and fly ash particles from a coal-fired power station, (2) diesel soot, (3) traffic dust from metal, tire and pavement abrasion, and (4) limestone-derived dust. Outside of the coal-mining area, traffic-derived dust defines the atmospheric baseline composition of the studied environment.

Rb, Sr, Nd, and Sm concentrations in quartz

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

Rossman, G.R.; Weis, D.; Wasserburg, G.J.

1987-09-01

The concentrations of Rb, Sr, Nd and Sm in quartz crystals from Crystal Peak, Colorado; Steward Mine, California; Tomas Gonzaga, Minas Gerais, Brazil; and Coleman Mines, Arkansas, were determined by isotope dilution mass spectrometry. Concentrations ranged from: 1.17 to 177 ppb Rb; 3.26 to 1027 ppm Sr; 0.0159 to 0.48 ppm Sm; 0.127 to 2.81 ppb Nd. In the Brazilian crystal, concentrations of these elements were correlated with the amount of fluid inclusion water measured visually by turbidity and quantitatively with infrared adsorption spectroscopy. The highest Rb content was found for a crystal free of visible inclusions, indicating that smallmore » amounts of Rb can also occur in quartz itself. Rb and Sr contents are much lower in synthetic quartz grown commercially from the Arkansas quartz.« less

Trace elements and radon in groundwater across the United States, 1992-2003

USGS Publications Warehouse

Ayotte, Joseph D.; Gronberg, Jo Ann M.; Apodaca, Lori E.

2011-01-01

Trace-element concentrations in groundwater were evaluated for samples collected between 1992 and 2003 from aquifers across the United States as part of the U.S. Geological Survey National Water-Quality Assessment Program. This study describes the first comprehensive analysis of those data by assessing occurrence (concentrations above analytical reporting levels) and by comparing concentrations to human-health benchmarks (HHBs). Data from 5,183 monitoring and drinking-water wells representing more than 40 principal and other aquifers in humid and dry regions and in various land-use settings were used in the analysis. Trace elements measured include aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), silver (Ag), strontium (Sr), thallium (Tl), uranium (U), vanadium (V), and zinc (Zn). Radon (Rn) gas also was measured and is included in the data analysis. Climate influenced the occurrence and distribution of trace elements in groundwater whereby more trace elements occurred and were found at greater concentrations in wells in drier regions of the United States than in humid regions. In particular, the concentrations of As, Ba, B, Cr, Cu, Mo, Ni, Se, Sr, U, V, and Zn were greater in the drier regions, where processes such as chemical evolution, ion complexation, evaporative concentration, and redox (oxidation-reduction) controls act to varying degrees to mobilize these elements. Al, Co, Fe, Pb, and Mn concentrations in groundwater were greater in humid regions of the United States than in dry regions, partly in response to lower groundwater pH and (or) more frequent anoxic conditions. In groundwater from humid regions, concentrations of Cu, Pb, Rn, and Zn were significantly greater in drinking-water wells than in monitoring wells. Samples from drinking-water wells in dry regions had greater concentrations of As, Ba, Pb, Li, Sr, V, and Zn, than samples from monitoring wells. In humid regions, however, concentrations of most trace elements were greater in monitoring wells than in drinking-water wells; the exceptions were Cu, Pb, Zn, and Rn. Cu, Pb, and Zn are common trace elements in pumps and pipes used in the construction of drinking-water wells, and contamination from these sources may have contributed to their concentrations. Al, Sb, Ba, B, Cr, Co, Fe, Mn, Mo, Ni, Se, Sr, and U concentrations were all greater in monitoring wells than in drinking-water wells in humid regions. Groundwater from wells in agricultural settings had greater concentrations of As, Mo, and U than groundwater from wells in urban settings, possibly owing to greater pH in the agricultural wells. Significantly greater concentrations of B, Cr, Se, Ag, Sr, and V also were found in agricultural wells in dry regions. Groundwater from dry-region urban wells had greater concentrations of Co, Fe, Pb, Li, Mn, and specific conductance than groundwater from agricultural wells. The geologic composition of aquifers and aquifer geochemistry are among the major factors affecting trace-element occurrence. Trace-element concentrations in groundwater were characterized in aquifers from eight major groups based on geologic material, including (1) unconsolidated sand and gravel; (2) glacial unconsolidated sand and gravel; (3) semiconsolidated sand; (4) sandstone; (5) sandstone and carbonate rock; (6) carbonate rock; (7) basaltic and other volcanic rock; and (8) crystalline rock. The majority of groundwater samples and the largest percentages of exceedences of HHBs were in the glacial and nonglacial unconsolidated sand and gravel aquifers; in these aquifers, As, Mn, and U are the most common trace elements exceeding HHBs. Overall, 19 percent of wells (962 of 5,097) exceeded an HHB for at least one trace element. The trace elements with HHBs included in this summary were Sb, As, Ba, Be, B, Cd, Cr,

Fluid/rock Interaction History of a Faulted Rhyolite-Granite Contact Determined by Sr- Pb-Isotopes, Th/U-Disequilibria and Elemental Distributions (Eastern Rhine Graben Shoulder, SW-Germany)

NASA Astrophysics Data System (ADS)

Marbach, T.; Mangini, A.; Kober, B.; Schleicher, A.; Warr, L. N.

2003-04-01

Major and trace element analyses allow to obtain information concerning the chemical changes induced by alteration. Differences are partly petrographic because the profile crosses the granite-rhyolite contact, but they are also due to different alteration levels induced by fluid circulation along the fault system which has drained the alteration processes. The granite-rhyolite contact constitutes the primary structure. Only the most incompatible elements (Si, Al, Zr, Hf) retain their original signatures and reflect a mixing between typical granite and rhyolite lithologies across the altered zones (cataclasite). The more mobile elements show a different composition within the altered zones (cataclasite) notably a high leaching of cations. The geochemical tracers also suggest at least one strong hydrothermal event with reducing conditions in the altered zones. The isotopic analyses delivered qualitative and temporal information. The use of several isotopic systems, Rb/Sr-, U/Pb-isotopes and Th/U disequilibria, reveals a complex history of polyphase fluid/rock interaction following the Permian volcanic extrusion, showing notable disturbances during the late Jurassic hydrothermal activities, the Tertiary rifting of the Rhine Graben and more recent Quaternary alteration. The granite zone of the sampling profile has underwent an event which set up a new Rb-Sr isotopic composition and reset the Rb/Sr system which originatly corresponded to the Carboniferous intrusion ages. The Rb-Sr data of the granite samples produce a whole rock isochron of 152 ± 5,7 Ma (2σ error) in good agreement with the well-known late Jurassic hydrothermal event (135--160 Ma). The rocks evolution lines for Pb support a Tertiary hydrothermal event (54 Ma ± 16; 1σ error), potentially connected with the development of the Rhine Graben. The profile samples have undergone uranium and thorium redistribution processes which have occurred within the last ˜10^6 years. The samples of the altered zones record a more complex history of uranium exchange with the aqueous phase. This uranium exchange is proportional to the porosity. The best approximation is reached for an exchange coefficient (λ_E) for uranium ranging from 2,5 E-06 [a-1] in the middle of the altered zones to 2,5 E-05 [a-1] on the sides of the altered zones.

LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

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

Harlan U. Anderson; Fatih Dogan; Vladimir Petrovsky

2002-03-31

This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. This period has continued to address the problem of making dense 1/2 to 5 {micro}m thick dense layers on porous substrates (the cathode LSM). Our current status is that we are making structures of 2-5 cm{sup 2} in area, which consist of either dense YSZ or CGO infiltrated into a 2-5 {micro}m thick 50% porous layer made of either nanoncrystalline CGO or YSZ powder. This composite structure coats a macroporous cathode or anode; which serves asmore » the structural element of the bi-layer structure. These structures are being tested as SOFC elements. A number of structures have been evaluated both as symmetrical and as button cell configuration. Results of this testing indicates that the cathodes contribute the most to cell losses for temperatures below 750 C. In this investigation different cathode materials were studied using impedance spectroscopy of symmetric cells and IV characteristics of anode supported fuel cells. Cathode materials studied included La{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (LSCF), La{sub 0.7}Sr{sub 0.2}MnO{sub 3} (LSM), Pr{sub 0.8}Sr{sub 0.2}Fe{sub 0.8}O{sub 3} (PSCF), Sm{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF), and Yb{sub .8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF). A new technique for filtering the Fourier transform of impedance data was used to increase the sensitivity of impedance analysis. By creating a filter specifically for impedance spectroscopy the resolution was increased. The filter was tailored to look for specific circuit elements like R//C, Warburg, or constant phase elements. As many as four peaks can be resolved using the filtering technique on symmetric cells. It may be possible to relate the different peaks to material parameters, like the oxygen exchange coefficient. The cathode grouped in order from lowest to highest ASR is LSCF < PSCF < SSCF < YSCF < LSM. The button cell results agree with this ordering indicating that this is an important tool for use in developing our understanding of electrode behavior in fuel cells.« less

Pb, Sr, and Nd isotopic compositions of a suite of Late Archean, igneous rocks, eastern Beartooth Mountains: implications for crust-mantle evolution

USGS Publications Warehouse

Wooden, J.L.; Mueller, P.A.

1988-01-01

A series of compositionally diverse, Late Archean rocks (2.74-2.79 Ga old) from the eastern Beartooth Mountains, Montana and Wyoming, U.S.A., have the same initial Pb, Sr, and Nd isotopic ratios. Lead and Sr initial ratios are higher and Nd initial ratios lower than would be expected for rocks derived from model mantle sources and strongly indicate the involvement of an older crustal reservoir in the genesis of these rocks. Crustal contamination during emplacement can be ruled out for a variety of reasons. Instead a model involving subduction of continental detritus and contamination of the overlying mantle as is often proposed for modern subduction environments is preferred. This contaminated mantle would have all the isotopic characteristics of mantle enriched by internal mantle metasomatism but would require no long-term growth or changes in parent to daughter element ratios. This contaminated mantle would make a good source for some of the Cenozoic mafic volcanics of the Columbia River, Snake River Plain, and Yellowstone volcanic fields that are proposed to come from ancient, enriched lithospheric mantle. The isotopic characteristics of the 2.70 Ga old Stillwater Complex are a perfect match for the proposed contaminated mantle which provides an alternative to crustal contamination during emplacement. The Pb isotopic characteristics of the Late Archean rocks of the eastern Beartooth Mountains are similar to those of other Late Archean rocks of the Wyoming Province and suggest that Early Archean, upper crustal rocks were common in this terrane. The isotopic signatures of Late Archean rocks in the Wyoming Province are distinctive from those of other Archean cratons in North America which are dominated by a MORB-like, Archean mantle source (Superior Province) and/or a long-term depleted crustal source (Greenland). ?? 1988.

Parenting and adolescent self-regulation.

PubMed

Purdie, Nola; Carroll, Annemaree; Roche, Lawrence

2004-12-01

This study examined the relationship between adolescents' academic and non-academic self-regulation (SR), authoritative parenting (as demonstrated by high levels of Involvement, Strictness, and Autonomy Granting), and parent self-efficacy in four areas. Participants were 214 Australian high school students and their parents. There was a moderate correlation (r = 0.63) between academic and non-academic SR. Adolescents and their parents differed significantly in their perceptions of parenting behaviours, with parents rating themselves higher than their children on Involvement, Autonomy Granting, and Strictness behaviours. A model of the relationships between the constructs was developed showing a strong path from parent self-efficacy to both academic and non-academic SR via high parental Involvement (as perceived by adolescents). Strict parenting and the granting by parents of psychological autonomy to their adolescent children did not appear to be important in the development of young people's self-regulatory behaviours.

Comprehensive Pb-Sr-Nd-Hf isotopic, trace element, and mineralogical characterization of mafic to ultramafic rock reference materials

NASA Astrophysics Data System (ADS)

Fourny, Anaïs.; Weis, Dominique; Scoates, James S.

2016-03-01

Controlling the accuracy and precision of geochemical analyses requires the use of characterized reference materials with matrices similar to those of the unknown samples being analyzed. We report a comprehensive Pb-Sr-Nd-Hf isotopic and trace element concentration data set, combined with quantitative phase analysis by XRD Rietveld refinement, for a wide range of mafic to ultramafic rock reference materials analyzed at the Pacific Centre for Isotopic and Geochemical Research, University of British Columbia. The samples include a pyroxenite (NIM-P), five basalts (BHVO-2, BIR-1a, JB-3, BE-N, GSR-3), a diabase (W-2), a dolerite (DNC-1), a norite (NIM-N), and an anorthosite (AN-G); results from a leucogabbro (Stillwater) are also reported. Individual isotopic ratios determined by MC-ICP-MS and TIMS, and multielement analyses by HR-ICP-MS are reported with 4-12 complete analytical duplicates for each sample. The basaltic reference materials have coherent Sr and Nd isotopic ratios with external precision below 50 ppm (2SD) and below 100 ppm for Hf isotopes (except BIR-1a). For Pb isotopic reproducibility, several of the basalts (JB-3, BHVO-2) require acid leaching prior to dissolution. The plutonic reference materials also have coherent Sr and Nd isotopic ratios (<50 ppm), however, obtaining good reproducibility for Pb and Hf isotopic ratios is more challenging for NIM-P, NIM-N, and AN-G due to a variety of factors, including postcrystallization Pb mobility and the presence of accessory zircon. Collectively, these results form a comprehensive new database that can be used by the geochemical community for evaluating the radiogenic isotope and trace element compositions of volcanic and plutonic mafic-ultramafic rocks.

OIB signatures in basin-related lithosphere-derived alkaline basalts from the Batain basin (Oman) - Constraints from 40Ar/39Ar ages and Nd-Sr-Pb-Hf isotopes

NASA Astrophysics Data System (ADS)

Witte, M.; Jung, S.; Pfänder, J. A.; Romer, R. L.; Mayer, B.; Garbe-Schönberg, D.

2017-08-01

Tertiary rift-related intraplate basanites from the Batain basin of northeastern Oman have low SiO2 (< 45.6 wt.%), high MgO (> 9.73 wt.%) and moderate to high Cr and Ni contents (Cr > 261 ppm, Ni > 181 ppm), representing near primary magmas that have undergone fractionation of mainly olivine and magnetite. Rare earth element systematics and p-T estimates suggest that the alkaline rocks are generated by different degrees of partial melting (4-13%) of a spinel-peridotite lithospheric mantle containing residual amphibole. The alkaline rocks show restricted variations of 87Sr/86Sr and 143Nd/144Nd ranging from 0.70340 to 0.70405 and 0.51275 to 0.51284, respectively. Variations in Pb isotopes (206Pb/204Pb: 18.59-18.82, 207Pb/204Pb: 15.54-15.56, 208Pb/204Pb: 38.65-38.98) of the alkaline rocks fall in the range of most OIB. Trace element constraints together with Sr-Nd-Pb isotope composition indicate that assimilation through crustal material did not affect the lavas. Instead, trace element variations can be explained by melting of a lithospheric mantle source that was metasomatized by an OIB-type magma that was accumulated at the base of the lithosphere sometimes in the past. Although only an area of less than 1000 km2 was sampled, magmatic activity lasted for about 5.5 Ma with a virtually continuous activity from 40.7 ± 0.7 to 35.3 ± 0.6 Ma. During this period magma composition was nearly constant, i.e. the degree of melting and the nature of the tapped source did not change significantly over time.

Trace element partitioning in fluvial tufa reveals variable portions of biologically influenced calcite precipitation

NASA Astrophysics Data System (ADS)

Ritter, Simon M.; Isenbeck-Schröter, Margot; Schröder-Ritzrau, Andrea; Scholz, Christian; Rheinberger, Stefan; Höfle, Bernhard; Frank, Norbert

2018-03-01

The formation of tufa is essentially influenced by biological processes and, in order to infer environmental information from tufa deposits, it has to be determined how the geochemistry of biologically influenced tufa deviates from equilibrium conditions between water and calcite precipitate. We investigated the evolution of the water and tufa geochemistry of consecutive tufa barrages in a small tufa-depositing creek in Southern Germany. High incorporation of divalent cations into tufa is ubiquitous, which is probably promoted by an influence of biofilms in the tufa element partitioning. The distribution coefficients for the incorporation of Mg, Sr and Ba into tufa at the Kaisinger creek D(Mg), D(Sr) and D(Ba) are 0.020-0.031, 0.13-0.18 and 0.26-0.43, respectively. This agrees with previous research suggesting that biofilm influenced tufa will be enriched in divalent cations over equilibrium values in the order of Mg < Sr < Ba. Furthermore, the incorporation of Mg, Sr and Ba into tufa of the Kaisinger creek decreases downstream, which can be attributed to changes of the relative portions of bio-influenced tufa formation with likely higher distribution coefficients and inorganically-driven tufa formation with likely lower distribution coefficients. Additionally, the distribution coefficients of metals in tufa of the Kaisinger creek D(Cd), D(Zn), D(Co) and D(Mn) show values of 11-22, 2.2-12, 0.7-4.9 and 30-57, respectively. These metals are highly enriched in upstream tufa deposits and their contents in tufa strongly decrease downstream. Such highly compatible elements could therefore be used to distinguish easily between different lateral sections in fluvial barrage-dam tufa depositional systems and could serve as a useful geochemical tool in studying ancient barrage-dam tufa depositional systems.

The effects of minor elements in La0.6Sr0.4Co0.2Fe0.8O3-δ cathodes on oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Oishi, Junya; Otomo, Junichiro; Oshima, Yoshito; Koyama, Michihisa

2015-03-01

It is known that the minor elements affect the performance of solid oxide fuel cell (SOFC). In this study, we focus on the influence of minor elements on the SOFC cathode properties. The Ca, Ba, Al, and Si, which originate from raw materials and production processes for SOFC cathodes, are investigated as minor elements that may have effect on the properties of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode. To examine the effects of minor elements on the cathode properties, Ca, Ba, Al, and Si with a controlled concentration are added to the LSCF reference sample. Conductivity relaxation measurements are conducted to determine the chemical diffusion coefficient (Dchem) and surface exchange coefficient (ktr), which governs the overpotential characteristics of the LSCF cathode. The results show that Al and Si have negative effects on both Dchem and ktr while Ca and Ba do not alter Dchem and show weakly positive effects on ktr. The effects of Ca and Ba for the cathode properties are discussed on the basis of XPS measurements.

Trace Element Data help Understanding the Origin of Lake Bosumtwi Crater Related Glass (Ivory Coast Tektites, Microtektites, Fall-Back Particles, Suevite Glass)

NASA Astrophysics Data System (ADS)

Deutsch, A.; Langenhorst, F.; Berndt, J.

2015-09-01

We report for the four internally rather homogeneous groups of glass (IVC, IVC-MT, BOT 12 [suevite], FBG) concentrations of major and 42 minor elements (in-situ data with LA-ICP-MS) as well as Sr-Nd, and DEGAS data.

Unreported Emission Lines of Rb, Ce, La, Sr, Y, Zr, Pb and Se Detected Using Laser-Induced Breakdown Spectroscopy

NASA Technical Reports Server (NTRS)

Lepore, K. H.; Mackie, J.; Dyar, M. D.; Fassett, C. I.

2017-01-01

Information on emission lines for major and minor elements is readily available from the National Institute of Standards and Technology (NIST) as part of the Atomic Spectra Database. However, tabulated emission lines are scarce for some minor elements and the wavelength ranges presented on the NIST database are limited to those included in existing studies. Previous work concerning minor element calibration curves measured using laser-induced break-down spectroscopy found evidence of Zn emission lines that were not documented on the NIST database. In this study, rock powders were doped with Rb, Ce, La, Sr, Y, Zr, Pb and Se in concentrations ranging from 10 percent to 10 parts per million. The difference between normalized spectra collected on samples containing 10 percent dopant and those containing only 10 parts per million were used to identify all emission lines that can be detected using LIBS (Laser-Induced Breakdown Spectroscopy) in a ChemCam-like configuration at the Mount Holyoke College LIBS facility. These emission spectra provide evidence of many previously undocumented emission lines for the elements measured here.

Biomonitoring of 33 Elements in Blood and Urine Samples from Coastal Populations in Sanmen County of Zhejiang Province.

PubMed

Zhang, Su-jing; Luo, Ru-xin; Ma, Dong; Zhuo, Xian-yi

2016-04-01

To determine the normal reference values of 33 elements, Ag, Al, As, Au, B, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Hg, Li, Mg, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, Th, Ti, Tl, U, V, Zn and Zr, in the blood and urine samples from the general population in Sanmen County of Zhejiang province, a typical coastal area of eastern China. The 33 elements in 272 blood and 300 urine samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The normality test of data was conducted using SPSS 17.0 Statistics. The data was compared with other reports. The normal reference values of the 33 elements in the blood and urine samples from the general population in Sanmen County were obtained, which of some elements were found to be similar with other reports, such as Co, Cu, Mn and Sr, while As, Cd, Hg and Pb were generally found to be higher than those previously reported. There was a wide variation between the reports from different countries in blood Ba. The normal reference values of the 33 elements in the blood and urine samples from the general population in Sanmen County are established, and successfully applied to two poisoning cases.

Electric field stimulation setup for photoemission electron microscopes.

PubMed

Buzzi, M; Vaz, C A F; Raabe, J; Nolting, F

2015-08-01

Manipulating magnetisation by the application of an electric field in magnetoelectric multiferroics represents a timely issue due to the potential applications in low power electronics and the novel physics involved. Thanks to its element sensitivity and high spatial resolution, X-ray photoemission electron microscopy is a uniquely suited technique for the investigation of magnetoelectric coupling in multiferroic materials. In this work, we present a setup that allows for the application of in situ electric and magnetic fields while the sample is analysed in the microscope. As an example of the performances of the setup, we present measurements on Ni/Pb(Mg(0.66)Nb(0.33))O3-PbTiO3 and La(0.7)Sr(0.3)MnO3/PMN-PT artificial multiferroic nanostructures.

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

Rapp, R.P.; Irifune, T.; Shimizu, N.

Isotopic and trace element geochemical studies of ocean island basalts (OIBs) have for many years been used to infer the presence of long-lived ({approx} 1-2 Ga old) compositional heterogeneities in the deep mantle related to recycling of crustal lithologies and marine and terrigenous sediments via subduction [e.g., Zindler, A., Hart, S.R., 1986. Chemical geodynamics. Annu. Rev. Earth Planet. Sci. 14, 493-571; Weaver, B.L., 1991. The origin of ocean island basalt end-member compositions: trace element and isotopic constraints. Earth Planet. Sci. Lett. 104, 381-397; Chauvel, C., Hofmann, A.W., Vidal, P., 1992. HIMU-EM: the French Polynesian connection. Earth Planet. Sci. Lett. 110,more » 99-119; Hofmann, A.W., 1997. Mantle geochemistry: the message from oceanic volcanism. Nature 385, 219-229; Willbold, M., Stracke, A., 2006. Trace element composition of mantle end-members: Implications for recycling of oceanic and upper and lower continental crust. Geochem. Geophys. Geosyst. Q04004. 7, doi:10.1029/2005GC001005]. In particular, models for the EM-1 type ('enriched mantle') OIB reservoir have invoked the presence of subducted, continental-derived sediment to explain high {sup 87}Sr/{sup 86}Sr ratios, low {sup 143}Nd/{sup 144}Nd and {sup 206}Pb/{sup 204}Pb ratios, and extreme enrichments in incompatible elements observed in OIB lavas from, for example, the Pitcairn Island group in the South Pacific [Woodhead, J.D., McCulloch, M.T., 1989; Woodhead, J.D., Devey, C.W., 1993. Geochemistry of the Pitcairn seamounts, I: source character and temporal trends. Earth Planet. Sci. Lett. 116, 81-99; Eisele, J., Sharma, M., Galer, S.J.G., Blichert-Toft, J., Devey, C.W., Hofmann, A.W., 2002. The role of sediment recycling in EM-1 inferred from Os, Pb, Hf, Nd, Sr isotope and trace element systematics of the Pitcairn hotspot. Earth Planet. Sci. Lett. 196, 197-212]. More recently, ultrapotassic, mantle-derived lavas (lamproites) from Gaussberg, Antarctica have been interpreted as the product of melting of deeply recycled (subducted) Archean-age metasediments in the mantle transition zone [Murphy, D.T., Collerson, K.D., Kamber, B.S., 2002. Lamproites from Gaussberg, Antartica: possible transition zone melts of Archaean subducted sediments. J. Petrol. 43, 981-1001]. Here we report the results of phase equilibria experiments on two different natural sedimentary compositions (a high-grade metapelite with < 1 wt.% H{sub 2}O, and a marine 'mud' with 8 wt.% H{sub O}) at 16-23 GPa. In both materials, the high-pressure mineral assemblages contain {approx} 15-30 wt.% K-hollandite (KAlSi{sub 3}O{sub 8}), in addition to stishovite, garnet, an Al-silicate phase (kyanite or phase egg), and a Fe-Ti spinel (corundum). Ion microprobe analyses of K-hollandite for a range of trace elements reveal that this phase controls a significant proportion of the whole-rock budget of incompatible, large-ion lithophile elements (LILEs, e.g., Rb, Ba, Sr, K, Pb, La, Ce and Th). Comparisons between the abundances and ratios of these elements in K-hollandite with those in EM-I type ocean-island basalts from Pitcairn Island and related seamounts, and with the Gaussberg lamproites, indicate the presence of deeply recycled, continent-derived sediments in these lavas sources. Our results suggest that the incompatible trace-element signature of EM-I OIB reservoirs in general and of the Gaussberg lamproites in particular can be attributed to recycling of K-hollandite-bearing continental sediments to transition zone depths.« less

Synthesis, spectroscopic characterization, thermal analysis and electrical conductivity studies of Mg(II), Ca(II), Sr(II) and Ba(II) vitamin B2 complexes

NASA Astrophysics Data System (ADS)

Refat, Moamen S.; Moussa, Mohamed A. A.; Mohamed, Soha F.

2011-05-01

Riboflavin (RF) complexes of Mg(II), Ca(II), Sr(II) and Ba(II) were successfully synthesized. Structures of metal complexes obtained were confirmed and characterized by elemental analysis, molar conductance, and infrared spectra. DC electrical conductivity measurements indicated that the alkaline earth metal (II) complexes of RF ligand are non-electrolytes. Elemental analysis of chelates suggest that the metal(II) ligand ratio is 1:2 with structure formula as [M(RF) 2( X) 2]· nH 2O. Infrared assignments clearly show that RF ligand coordinated as a bidentate feature through azomethine nitrogen of pyrazine ring and C dbnd O of pyrimidine-2,4-dione. Thermal analyses of Mg(II), Ca(II), Sr(II) and Ba(II) complexes were investigated using (TG/DSC) under atmospheric nitrogen between 30 and 800 °C. The surface morphology of the complexes was studied by SEM. The electrical conductivities of RF and its metal complexes were also measured with DC electrical conductivity in the temperature range from room to 483 K.

Experimental Modeling of the Impulse Diffraction System with a "White" SR Beam

NASA Astrophysics Data System (ADS)

Fedotov, M. G.; Aleshaev, A. N.

Some matrix detectors (CCD and CIS) have direct X-ray sensitivity and can operate as dispersionless spectrometers with a very large number of elements (106 and more). In the case of the impulse diffraction such detector can simultaneously record a significant number of independent events. In the reading the position and energy of the absorbed X-ray photon may be restored for each event. The mathematical processing of the received data with respect to the Bragg condition can theoretically lead to the coordinates of the events of one fixed energy and to form an analogue of powder diffraction patterns. In this case the registration can be performed on the "white" SR beam for a short time (up to 1 ns or less). The possibility of using of the 2000-element linear CCD ILX511 (Sony) as X-ray dispersionless spectrometer allowed to conduct simulation experiments to obtain diffraction patterns of graphite, boron nitride, boric acid and TNT-hexogen solid detonation products. SR beam from VEPP-3 storage ring was modulated by a mechanical chopper and statistics were provided by a multiple recording with on-line processing.

Mafic dykes intrusive into Pre-Cambrian rocks of the São Luís cratonic fragment and Gurupi Belt (Parnaíba Province), north-northeastern Brazil: Geochemistry, Sr-Nd-Pb-O isotopes, 40Ar/39Ar geochronology, and relationships to CAMP magmatism

NASA Astrophysics Data System (ADS)

Klein, Evandro L.; Angélica, Rômulo S.; Harris, Chris; Jourdan, Fred; Babinski, Marly

2013-07-01

Dykes of diabase and microgabbro intruded into Pre-Cambrian rocks of the São Luís cratonic fragment and Gurupi Belt, which are tectonic and erosive windows of the Parnaíba Basin in north-northeastern Brazil. Ar-Ar ages were determined, and major, trace element, and Nd-Sr-Pb-O isotopic compositions of these dykes were measured to provide insights into their age, and into the nature of their mantle sources and petrogenetic processes. The data have also been used to compare the chemical and isotopic signatures of the dykes with those of the Central Atlantic Magmatic Province (CAMP). Four chemical groups of mafic dykes have been identified. These comprise two subtypes of high-Ti rocks (i) HTi-1 (TiO2 < 2.3 wt.%; SiO2 > 47 wt.%), (ii) HTi-2 (TiO2 > 2.7 wt.%; SiO2 > 47 wt.%), in addition to (iii) evolved high-Ti (TiO2 > 4 wt.%; SiO2 of ~ 46 wt.%) and (iv) low-Si (TiO2 > 2.2 wt.%; SiO2 < 45 wt.%) rocks. 40Ar/39Ar geochronology of plagioclase returned ages of 201 ± 4 Ma and 193 ± 10 Ma for the HTi-2 subtype, and of 201 ± 2 Ma and 207 ± 9 Ma for the evolved high-Ti group. The HTi-1 and low-Si groups presented highly disturbed age spectra, and did not allow the definition of their emplacement ages. The Argon data indicate an age > 200 Ma for the low-Si group and are dubious with respect to the age of theHTi-1 subtype, if coeval with (i.e., ~ 200 Ma), or older than, the HTi-2 and evolved high-Ti types. All groups present δ18O values of pyroxene that are compatible with uncontaminated mantle-derived magmas. The HTi-1 subtype (average 143Nd/144Nd200 = 0.512644; 87Sr/86Sr200 = 0.7035; 206Pb/204Pb of 17.86) shows the less enriched and less fractionated (more primitive) trace element distribution of all groups. The HTi-2 subtype shows enriched trace element pattern and depleted Nd-Sr signature (143Nd/144Nd200 = 0.512610; 87Sr/86Sr200 = 0.7037) and average 206Pb/204Pb ratios of 17.23. The evolved high-Ti chemical group shows average ratios of 143Nd/144Nd200 = 0.512558, 87Sr/86Sr200 = 0.7035, and 206Pb/204Pb of 16.88, and the more enriched trace-elements signature among the four groups. The chemical and isotopic compositions and trends of the HTi-1/HTi-2/EHTi types are consistent with their derivation from an asthenosphere-derived parental magma further modified by differentiation and minimal crust contamination (higher in the HTi-2 and EHTi types), and by the derivation of one type from another via fractional crystallization. These high- and evolved high-TiO2 types show ages and some chemical and isotopic features that are consistent with those of the CAMP magmatism. Some differences found are ascribed to petrogenetic processes, such as magma differentiation. A combination of warming of the mantle and edge-driven convection beneath the Pangea supercontinent after the closure of the Neoproterozoic (Brasiliano/Pan-African) orogenies in the Ediacaran-Cambrian boundary might have triggered the magmatic event. The low-Si type shows paired Ta-Nb and Zr-Hf depletions, and depleted Sr-Nd (average 143Nd/144Nd200 = 0.512687; 87Sr/86Sr200 = 0.703) and enriched Pb (206Pb/204Pb of 18.66) isotopic compositions that may be interpreted to result either from interaction of a subcontinental lithospheric mantle with products of an earlier subduction or by contamination of the mantle-derived magma during ascent and emplacement in the continental crust. It is hypothesized that these dykes were emplaced in the Ediacaran-Cambrian boundary, after the Neoproterozoic orogeny that built up the Gurupi Belt and in the early extensional stages that preceded the formation of the Parnaíba Basin.

Electrochemical and diffusional insights of combustion synthesized SrLi2Ti6O14 negative insertion material for Li-ion Batteries

NASA Astrophysics Data System (ADS)

Dayamani, Allumolu; Shinde, Ganesh S.; Chaupatnaik, Anshuman; Rao, R. Prasada; Adams, Stefan; Barpanda, Prabeer

2018-05-01

Solvothermal synthetic routes can provide energy-savvy platforms to fabricate battery anode materials involving relatively milder annealing steps vis-à-vis the conventional solid-state synthesis. These energy efficient routes in turn restrict aggressive grain growth to form nanoscale particles favouring efficient Li+ diffusion. Here, we report an economic solution combustion synthesis of SrLi2Ti6O14 anode involving nitrate-urea complexation with a short annealing duration of only 2 h (900 °C). Rietveld refinement confirms the phase purity of target product assuming an orthorhombic framework (Cmca symmetry). It delivers reversible capacity of ∼125 mAh.g-1 at a rate of C/20 involving a 1.38 V Ti4+/Ti3+ redox activity with excellent rate kinetics and cycling stability. Bond valence site energy (BVSE) calculations gauge SrLi2Ti6O14 to be an anisotropic 3D Li+ ion conductor with the highest ionic conductivity along the c direction. The electrochemical and diffusional pathways have been elucidated for combustion prepared SrLi2Ti6O14 as an efficient and safe negative electrode candidate for Li-ion batteries.

Recycled oceanic crust in the source of 90-40 Ma basalts in North and Northeast China: Evidence, provenance and significance

NASA Astrophysics Data System (ADS)

Xu, Yi-Gang

2014-10-01

Major, trace element and Sr-Nd-Pb isotopic data of basalts emplaced during 90-40 Ma in the North and Northeast China are compiled in this review, with aims of constraining their petrogenesis, and by inference the evolution of the North China Craton during the late Cretaceous and early Cenozoic. Three major components are identified in magma source, including depleted component I and II, and an enriched component. The depleted component I, which is characterized by relatively low 87Sr/86Sr (<0.7030), moderate 206Pb/204Pb (18.2), moderately high εNd (∼4), high Eu/Eu∗ (>1.1) and HIMU-like trace element characteristics, is most likely derived from gabbroic cumulate of the oceanic crust. The depleted component II, which distinguishes itself by its high εNd (∼8) and moderate 87Sr/86Sr (∼0.7038), is probably derived from a sub-lithospheric ambient mantle. The enriched component has low εNd (2-3), high 87Sr/86Sr (>0.7065), low 206Pb/204Pb (17), excess Sr, Rb, Ba and a deficiency of Zr and Hf relative to the REE. This component is likely from the basaltic portion of the oceanic crust, which is variably altered by seawater and contains minor sediments. Comparison with experimental melts and trace element modeling suggest that these recycled oceanic components may be in form of garnet pyroxenite/eclogite. These components are young (<0.5 Ga) and show an Indian-MORB isotopic character. Given the share of this isotopic affinity by the extinct Izanaghi-Pacific plate, currently stagnated within the mantle transition zone, we propose that it ultimately comes from the subducted Pacific slab. Eu/Eu∗ and 87Sr/86Sr of the 90-40 Ma magmas increases and decreases, respectively, with decreasing emplacement age, mirroring a change in magma source from upper to lower parts of subducted oceanic crust. Such secular trends are created by dynamic melting of a heterogeneous mantle containing recycled oceanic crust. Due to different melting temperature of the upper and lower ocean crust and progressive thinning of the lithosphere, the more fertile basaltic crustal component is preferentially sampled during the early stage of volcanism, whereas the more depleted gabbroic lower crust and lithospheric mantle components are preferentially sampled during a late stage. This model is consistent with a protracted destruction process of the lithosphere beneath eastern China. The presence of significant recycled oceanic crust components in the 90-40 Ma basalts highlights the influence of Pacific subduction on the deep processes in the North China Craton, which can be traced back at least to the late Cretaceous. This, along with the conjugation of crustal deformation pattern in this region with the movement of the Pacific plate, makes the Pacific subduction as a potential trigger of the destruction of the North China Craton. Geophysical investigations and morphological analyses indicate that decratonization is largely confined to east of the NSGL, whereas to west of NSGL, in particular the Ordos basin, characteristics typical of a craton are observed (Menzies et al., 2007; Zhu et al., 2011). This spatial pattern of craton destruction, together with NE-NNE-oriented extensional basins, main structural alignments and metamorphic core complexes (Zheng et al., 1978; Ye et al., 1987; Ren et al., 2002; Liu et al., 2006; Zhu G et al., 2012), is consistent with the subduction direction of the Pacific plate. Two main episodes of late Mesozoic magmatism have been identified in the Jurassic and the early Cretaceous. These correspond to the subduction of the Pacific plate underneath the Eurasian content and to subsequent extensions, respectively (Wu et al., 2005, 2006). Global tomography studies indicate that the subducted Pacific oceanic slab has become stagnant within the mantle transition zone and extended subhorizontally westward beneath the East Asian continent (Fukao et al., 1992; Huang and Zhao, 2006; Chen and Ai, 2009; Van der Hilst and Li, 2010). The western end of this stagnant slab does not go beyond the NNE-trending NSGL (Huang and Zhao, 2006; Xu, 2007). Given the subduction of Pacific plate underneath eastern Asian continent, the slab-derived materials are expected to be involved in the sources of the Mesozoic-Cenozoic magmas in this region. Recent studies have shown the ubiquitous presence of subduction-related components in late Cenozoic basalts in eastern China (Zhang et al., 2009; Xu et al., 2012b; Sakuyama et al., 2013). However, it remains unclear whether similar recycled oceanic components are present in earlier basalts (i.e., those emplaced during 90-40 Ma, Fig. 1), for which high quality geochemical data are not available until very recently (Zhang et al., 2008; Kuang et al., 2012; Xu et al., 2012a). In addition, the provenance of recycled oceanic components, if any, is highly relevant to the proposal of the Pacific subduction as one of the possible triggers of the destruction of the NCC. The timing of the first appearance of oceanic components in magmas will provide constraints on the role of the Pacific subduction on the evolution of the NCC.The objective of this study is to review and compile major, trace elements and Sr-Nd-Pb isotopic compositions of mafic magmas emplaced since 90 Ma in North and Northeastern China, and to use these data to elaborate their petrogenesis. We will demonstrate the ubiquitous involvement of subduction-related components in the magma sources. Furthermore, temporal variation in geochemical features suggests that different parts of the recycled oceanic crust are preferentially sampled at different time. In collaborating with melting solidus temperature and the melting column concept, this is interpreted as differential melting of upwelling heterogeneous mantle as a result of lithospheric thinning. The peculiar isotopic compositions of these oceanic crust components suggests a link with the subducted Pacific slab, which currently stagnates at the mantle transition zone beneath the eastern Asian continental margin (Fukao et al., 1992; Huang and Zhao, 2006). This study therefore provides petrological evidence for the effect of Pacific subduction on the studied region, rendering the Pacific subduction as a potential trigger of the destruction of the NCC.

Trace and Ultra-trace Elements in the Deepest Part of the Vostok Ice Core, Antarctica: Geochemical Characterization of the Sub-glacial Lake Environment

NASA Astrophysics Data System (ADS)

Turetta, C.; Planchon, F.; Gabrielli, P.; Cozzi, G.; Cairns, W.; Barbaro, E.; Petit, J. R.; Bulat, S.; Boutron, C.; Barbante, C.

2016-12-01

We present in this study comprehensive data on the occurrence of 25 trace and ultra-trace elements in the deepest part of the Vostok ice core. The determination of Li, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sb, Ba, Pb, Bi and U has been performed in the different types of ice encountered from 3271 m to 3609 m of depth, corresponding to atmospheric ice, glacial flour and to accreted ice originating from the freezing of Lake Vostok waters. From atmospheric ice and glacial flour, the relative contributions of primary aerosols were evaluated for each element using a chemical mass balance approach in order to provide a first order evaluation of their partition between soluble (sea-salt) and insoluble (wind-blown dust) fractions in the ice. Sea-salt spray aerosols are the main source of impurities to the ice for certain elements (Na, Mg and K levels, and in a lesser extent to Ca, Sr, Rb, Li and U) while for other elements (Al, V, Cr, Mn, Fe, Co, Cu, Zn, Mo, Sb, Ba and Pb as well as the non sea salt fractions of Mg, K, Ca, Sr, Rb, Li and U) dust inputs appear to primarily control their depositional variability. For the glacial flour, the comparable levels of elements with the overlying atmospheric ice suggest that incorporation of abrasion debris at the glacier is quite limited in the sections considered. For the accreted ice originating from the subglacial waters of Lake Vostok, we observed a major chemical shift in the composition of the ice showing two distinct trends that we assumed to be derived from the chemical speciation of elements. The study of the glacier ice and the glacial flour has allowed us to perform a detailed characterisation of elemental abundances related to the aerosol sources variability and also to illustrate the interaction between the ice-sheet and the bedrock.

Depleted arc volcanism in the Alboran Sea and shoshonitic volcanism in Morocco: geochemical and isotopic constraints on Neogene tectonic processes

NASA Astrophysics Data System (ADS)

Gill, R. C. O.; Aparicio, A.; El Azzouzi, M.; Hernandez, J.; Thirlwall, M. F.; Bourgois, J.; Marriner, G. F.

2004-12-01

Samples of volcanic rocks from Alborán Island, the Alboran Sea floor and from the Gourougou volcanic centre in northern Morocco have been analyzed for major and trace elements and Sr-Nd isotopes to test current theories on the tectonic geodynamic evolution of the Alboran Sea. The Alborán Island samples are low-K tholeiitic basaltic andesites whose depleted contents of HFS elements (˜0.5×N-MORB), especially Nb (˜0.2×N-MORB), show marked geochemical parallels with volcanics from immature intra-oceanic arcs and back-arc basins. Several of the submarine samples have similar compositions, one showing low-Ca boninite affinity. 143Nd/ 144Nd ratios fall in the same range as many island-arc and back-arc basin samples, whereas 87Sr/ 86Sr ratios (on leached samples) are somewhat more radiogenic. Our data point to active subduction taking place beneath the Alboran region in Miocene times, and imply the presence of an associated back-arc spreading centre. Our sea floor suite includes a few more evolved dacite and rhyolite samples with ( 87Sr/ 86Sr) 0 up to 0.717 that probably represent varying degrees of crustal melting. The shoshonite and high-K basaltic andesite lavas from Gourougou have comparable normalized incompatible-element enrichment diagrams and Ce/Y ratios to shoshonitic volcanics from oceanic island arcs, though they have less pronounced Nb deficits. They are much less LIL- and LREE-enriched than continental arc analogues and post-collisional shoshonites from Tibet. The magmas probably originated by melting in subcontinental lithospheric mantle that had experienced negligible subduction input. Sr-Nd isotope compositions point to significant crustal contamination which appears to account for the small Nb anomalies. The unmistakable supra-subduction zone (SSZ) signature shown by our Alboran basalts and basaltic andesite samples refutes geodynamic models that attribute all Neogene volcanism in the Alboran domain to decompression melting of upwelling asthenosphere arising from convective thinning of over-thickened lithosphere. Our data support recent models in which subsidence is caused by westward rollback of an eastward-dipping subduction zone beneath the westernmost Mediterranean. Moreover, severance of the lithosphere at the edges of the rolling-back slab provides opportunities for locally melting lithospheric mantle, providing a possible explanation for the shoshonitic volcanism seen in northern Morocco and more sporadically in SE Spain.

Strontium isotopic signatures of oil-field waters: Applications for reservoir characterization

USGS Publications Warehouse

Barnaby, R.J.; Oetting, G.C.; Gao, G.

2004-01-01

The 87Sr/86Sr compositions of formation waters that were collected from 71 wells producing from a Pennsylvanian carbonate reservoir in New Mexico display a well-defined distribution, with radiogenic waters (up to 0.710129) at the updip western part of the reservoir, grading downdip to less radiogenic waters (as low as 0.708903 to the east. Salinity (2800-50,000 mg/L) displays a parallel trend; saline waters to the west pass downdip to brackish waters. Elemental and isotopic data indicate that the waters originated as meteoric precipitation and acquired their salinity and radiogenic 87Sr through dissolution of Upper Permian evaporites. These meteoric-derived waters descended, perhaps along deeply penetrating faults, driven by gravity and density, to depths of more than 7000 ft (2100 m). The 87 Sr/86Sr and salinity trends record influx of these waters along the western field margin and downdip flow across the field, consistent with the strong water drive, potentiometric gradient, and tilted gas-oil-water contacts. The formation water 87Sr/86Sr composition can be useful to evaluate subsurface flow and reservoir behavior, especially in immature fields with scarce pressure and production data. In mature reservoirs, Sr Sr isotopes can be used to differentiate original formation water from injected water for waterflood surveillance. Strontium isotopes thus provide a valuable tool for both static and dynamic reservoir characterization in conjunction with conventional studies using seismic, log, core, engineering, and production data. Copyright ??2004. The American Association of Petroleum Geologist. All rights reserved.

Age and composition of Archean crystalline rocks from the southern Madison Range, Montana. Implications for crustal evolution in the Wyoming craton

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

Mueller, P.A.; Shuster, R.D.; Wooden, J.L.

1993-04-01

The southern Madison Range of southwestern Montana contains two distinct Precambrian lithologic assemblages: (1) a complex of tonalitic to granitic gneisses that has been thrust over (2) a medium-grade metasupracrustal sequence dominated by pelitic schist. Crystallization ages for the protolith of a granodioritic gneiss that intruded the metasupracrustal sequence ([approximately]2.6 Ga)-along with an intercalated meta-andesite ([approximately]2.7 Ga) confirm the sequence as Archean. Chemical (major and trace element), isotopic (Rb-Sr, Sm-Nd, Pb-Pb), and geochronologic (U-Pb zircon) data for selected components of the gneiss complex indicate two groups of gneisses: an older, tonalitic to trondhjemitic group ([approximately]3.3 Ga) and a younger, mostlymore » granitic group ([approximately]2.7 Ga). Both groups of gneisses exhibit the radiogenic Pb and nonradiogenic Nd isotopic signature characteristic of Middle and Late Archean rocks from throughout the Wyoming province. The older gneisses, in particular, appear to be compositionally, isotopically, and chronologically comparable to other Middle Archean gneisses from the northern part of the province (for example, Beartooth Mountains). The Late Archean gneisses, however, exhibit some distinct differences relative to their temporal counterparts, including (1) trace-element patterns that are more suggestive of crustal melts than subduction activity and (2) higher initial Sr isotopic ratios that suggest more involvement of older crust in their petrogenesis. These comparisons suggest that the juxtaposition of Late Archean terranes in the northern Wyoming province was the result, at least in part, of intracratonic processes. 41 refs., 6 figs., 2 tabs.« less

Hair for a long-term biological indicator tissue for assessing the strontium nutritional status of men and women.

PubMed

Prejac, J; Višnjević, V; Skalny, A A; Grabeklis, A R; Mimica, N; Momčilović, B

2017-07-01

Strontium (Sr) is a trace element that closely resembles calcium metabolism. At the present time there is no available long-term biological indicator tissue for assessing the human Sr nutritional status. Here we have presented a novel concept on how to assess the Sr nutritional status by studying the frequency distribution properties of hair Sr ( Sr H) concentration. In this prospective, observational, cross-sectional, and exploratory epidemiological study, we analyzed Sr H in 311 apparently healthy adult Croatians (123 men, 188 women). Hair strontium was analyzed by the ICP-MS. The natural frequency distribution of Sr H followed the Power law, so that the data were analyzed by fitting the logistic bioassay sigmoid curve (ogive) of median derivatives. Women tend to accumulate three and a half time more Sr H than men (median men 867ngg -1 vs. median women 3120ngg -1 ). The normal (adequate) linear physiological response range of the sigmoid curve was 351-3489ngg -1 for men and 846-8457ngg -1 for women. Values below that linear range are considered to indicate deficient Sr nutritional status, whereas values above that linear range indicate excessive strontium exposure. Hair, as a long-term, and whole blood as a short-term biological indicator tissues were not commensurable entities. Similarly, Sr H accumulation was not age dependent in either men or women. Hair strontium is a reliable long-term biological indicator tissue for assessing the strontium nutritional status. Copyright © 2017 Elsevier GmbH. All rights reserved.

Petrogenesis of Late Jurassic granodiorites from Gutian, Fujian Province, South China: Implications for multiple magma sources and origin of porphyry Cu-Mo mineralization

NASA Astrophysics Data System (ADS)

Li, Bin; Jiang, Shao-Yong; Lu, An-Huai; Lai, Jian-Qing; Zhao, Kui-Dong; Yang, Tao

2016-11-01

The Gutian porphyry Cu-Mo deposit is a newly proved porphyry copper deposit in the coastal South China associated with granodioritic porphyries. In this study, zircon U-Pb ages and Hf isotope data, as well as geochemical and Sr-Nd-Pb-Re-Os isotopic compositions, are reported for these intrusions and minerals. Both zircon U-Pb and molybdenite Re-Os dating suggest that the Gutian granodiorite porphyries and related mineralization formed at 160 Ma. The Gutian granodiorites show a low-Mg adakitic geochemical affinity, with relatively high K2O but low Cr and Ni contents. These rocks have initial (87Sr/86Sr)i ratios of 0.7085 to 0.7097, negative εNd(t) values (- 12.5 to - 7.8), (206Pb/204Pb)t ratios of 18.048 to 18.241, (207Pb/204Pb)t ratios of 15.609 to 15.628, and (208Pb/204Pb)t ratios of 38.494 to 38.667. Zircons from the granodiorites have negative εHf(t) values of - 15.7 to - 8.5, which are close to those of Cathaysia crust-derived melts. Geochemical and Sr-Nd-Pb-Hf isotopic compositions suggest that they may be derived from Late Jurassic thickened juvenile lower crust. These lower crustal magma sources may not only contain pre-Proterozoic basement rocks, but also involve Triassic and Middle-Late Jurassic arc magmas within the lower crust, which were likely derived from an enriched mantle source associated with paleo-Pacific Plate subduction from the Middle to Late Jurassic. The Gutian ore-related granodiorites represent a new example for significant contributions of ancient subduction melts and enriched mantle-derived sources for porphyry-type magmatism and Cu-Mo mineralization, which occurred in response to an arc regime during the Middle to Late Jurassic in South China. Supplemental Table S2. Hf isotopic compositions of zircons from the studied rocks from the Gutian porphyry deposit in South China. Supplemental Table S3. Statistics for zircon U-Pb ages and Hf isotope compositions from Gutian granodiorites in South China Supplemental Table S4. Major element (wt.%) and trace element (ppm) concentrations of Gutian intrusions in Fujian Province, South China. Supplemental Table S5. Sr and Nd isotopic compositions of the studied rocks from the Gutian porphyry deposit in Fujian Province, South China. Supplemental Table S6. Pb isotopic compositions of the studied rocks from the Gutian porphyry deposit in South China. Supplemental Table S7. Re-Os isotopic compositions of molybdenite from the Gutian porphyry deposit in South China.

Isotopic evolution of Mauna Kea volcano: Results from the initial phase of the Hawaii Scientific Drilling Project

USGS Publications Warehouse

Lassiter, J.C.; DePaolo, D.J.; Tatsumoto, M.

1996-01-01

We have examined the Sr, Nd, and Pb isotopic compositions of Mauna Kea lavas recovered by the first drilling phase of the Hawaii Scientific Drilling Project. These lavas, which range in age from ???200 to 400 ka, provide a detailed record of chemical and isotopic changes in basalt composition during the shied/postshield transition and extend our record of Mauna Kea volcanism to a late-shield period roughly equivalent to the last ???100 ka of Mauna Loa activity. Stratigraphic variations in isotopic composition reveal a gradual shift over time toward a more depleted source composition (e.g., higher 143Nd/144Nd, lower 87Sr/86Sr, and lower 3He/4He). This gradual evolution is in sharp contrast with the abrupt appearance of alkalic lavas at ???240 ka recorded by the upper 50 m of Mauna Kea lavas from the core. Intercalated tholeiitic and alkalic lavas from the uppermost Mauna Kea section are isotopically indistinguishable. Combined with major element evidence (e.g., decreasing SiO2 and increasing FeO) that the depth of melt segregation increased during the transition from tholeiitic to alkalic volcanism, the isotopic similarity of tholeiitic and alkalic lavas argues against significant lithosphere involvement during melt generation. Instead, the depleted isotopic signatures found in late shield-stage lavas are best explained by increasing the proportion of melt generated from a depleted upper mantle component entrained and heated by the rising central plume. Direct comparison of Mauna Kea and Mauna Loa lavas erupted at equivalent stages in these volcanoes' life cycles reveals persistent chemical and isotopic differences independent of the temporal evolution of each volcano. The oldest lavas recovered from the drillcore are similar to modern Kilauea lavas, but are distinct from Mauna Loa lavas. Mauna Kea lavas have higher 143Nd/144Nd and 206Pb/204Pb and lower 87Sr/86Sr. Higher concentrations of incompatible trace elements in primary magmas, lower SiO2, and higher FeO also indicate that Mauna Kea lavas formed through smaller degrees of partial melting at greater depth than Mauna Loa lavas. These chemical and isotopic differences are consistently found between volcanoes along the western "Loa" and eastern "Kea" trends and reflect large-scale variations in source composition and melting environment. We propose a simple model of a radially zoned plume centered beneath the Loa trend. Loa trend lavas generated from the hot plume axis reflect high degrees of partial melting from a source containing a mixture of enriched plume-source material and entrained lower mantle. Kea trend lavas, in contrast, are generated from the cooler, peripheral portions of the plume, record lower degrees of partial melting, and tap a source containing a greater proportion of depleted upper mantle.

Reconstruction of dietary habits on the basis of dental microwear and trace elements analysis of individuals from Gán cemetery (district Galanta, Slovakia).

PubMed

Tibenská, Kristína Domonkosová; Bodoriková, Silvia; Katina, Stanislav; Kovácsová, Veronika; Kubová, Jana; Takács, Michal

2010-01-01

The aim of the study was to determine the diet of a historical human population. Dental microwear and trace elements were analyzed. Although 38 individuals had been buried in the cemetery, only 13 of them were suitable for the analysis of trace elements and 17 skeletal remains for microwear analysis. Buccal microwear has been studied in a sample of 17 teeth from Gán cemetery. Teeth molds of the buccal surface were obtained and observed at 120x magnification with a scanning electron microscope (SEM). Length and orientation of each striation have been determined with a SigmaScan Pro 5.0 image analysis program. The results of the analysis from Gán were compared with the previous study in a sample of 153 molar teeth from different modern hunter-gatherer, pastorals, and agriculturalist groups, with different diets (Inuit, Fueguians, Bushmen, Australian aborigines, Andaman's, Indians from Vancouver, Veddahs, Tasmanians, Lapps, and Hindus), preserved at museum collections. Buccal dental microwear density and length by orientation showed almost an inclination to hunter-gatherers from tropic and arid climates. The sample for the trace elements analysis consisted of 10 permanent molars and 3 permanent premolars. All analyzed teeth were intact, with fully developed roots, without dental caries, calculus and abrasion. Samples were analyzed using the method of optical emission spectrometry with inductively coupled plasma. Three elements: Ca, Sr, and Zn were chosen as basic diet determinants. Concentrations of these elements and their ratios were used for description of a relative proportion of plant and animal protein in a diet. The values of the Sr and Zn concentrations indicate that a diet of investigated population was rich in plant food. Higher Sr values in women can indicate lower proportion of animal protein in a diet, but significant differences have not been found. Differences between non-adult and adult individuals and between individuals with and without grave furnishings have also not been significant.

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.

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

Temporal stability and rates of post-depositional change in geochemical signatures of brown trout Salmo trutta scales.

PubMed

Ryan, D; Shephard, S; Kelly, F L

2016-09-01

This study investigates temporal stability in the scale microchemistry of brown trout Salmo trutta in feeder streams of a large heterogeneous lake catchment and rates of change after migration into the lake. Laser-ablation inductively coupled plasma mass spectrometry was used to quantify the elemental concentrations of Na, Mg, Mn, Cu, Zn, Ba and Sr in archived (1997-2002) scales of juvenile S. trutta collected from six major feeder streams of Lough Mask, County Mayo, Ireland. Water-element Ca ratios within these streams were determined for the fish sampling period and for a later period (2013-2015). Salmo trutta scale Sr and Ba concentrations were significantly (P < 0·05) correlated with stream water sample Sr:Ca and Ba:Ca ratios respectively from both periods, indicating multi-annual stability in scale and water-elemental signatures. Discriminant analysis of scale chemistries correctly classified 91% of sampled juvenile S. trutta to their stream of origin using a cross-validated classification model. This model was used to test whether assumed post-depositional change in scale element concentrations reduced correct natal stream classification of S. trutta in successive years after migration into Lough Mask. Fish residing in the lake for 1-3 years could be reliably classified to their most likely natal stream, but the probability of correct classification diminished strongly with longer lake residence. Use of scale chemistry to identify natal streams of lake S. trutta should focus on recent migrants, but may not require contemporary water chemistry data. © 2016 The Fisheries Society of the British Isles.

Soil properties, strontium isotopic signatures and multi-element profiles to authenticate the origin of vegetables from small-scale regions: illustration with early potatoes from southern Italy.

PubMed

Zampella, Mariavittoria; Quétel, Christophe R; Paredes, Eduardo; Goitom Asfaha, Daniel; Vingiani, Simona; Adamo, Paola

2011-10-15

We propose a method for the authentication of the origin of vegetables grown under similar weather conditions, in sites less than 10 km distance from the sea and distributed over a rather small scale area (58651 km(2)). We studied how the strontium (Sr) isotopic signature and selected elemental concentrations ([Mn], [Cu], [Zn], [Rb], [Sr] and [Cd]) in early potatoes from three neighbouring administrative regions in the south of Italy were related to the geological substrate (alluvial sediments, volcanic substrates and carbonate rocks) and to selected soil chemical properties influencing the bioavailability of elements in soils (pH, cation exchange capacity and total carbonate content). Through multiple-step multivariate statistics (PLS-DA) we could assign 26 potatoes (including two already commercialised samples) to their respective eight sites of production, corresponding to the first two types of geological substrates. The other 12 potatoes from four sites of production had similar characteristics in terms of the geological substrate (third type) and these soil properties could be grouped together. In this case, more discriminative parameters would be required to allow the differentiation between sites. The validation of our models included external prediction tests with data of potatoes harvested the year before and a study on the robustness of the uncertainties of the measurement results. Annual variations between multi-elemental and Sr isotopic fingerprints were observed in potatoes harvested from soils overlying carbonate rocks, stressing the importance of testing long term variations in authentication studies. Copyright © 2011 John Wiley & Sons, Ltd. and European Union [2011].

SR-XFA as a method of choice in the search of signals of changing palaeoclimates in the sediments of Lake Baikal, compared to INAA and ICP-MS

NASA Astrophysics Data System (ADS)

Phedorin, M. A.; Bobrov, V. A.; Goldberg, E. L.; Navez, J.; Zolotaryov, K. V.; Grachev, M. A.

2000-06-01

Sediments of Lake Baikal obtained on top of the underwater Akademichesky Ridge for reconstruction of the palaeoclimates of Holocene and Upper Pleistocene were subjected to elemental analysis with three methods: (i) synchrotron radiation X-ray fluorescent analysis (SR-XFA); (ii) instrumental neutron activation analysis (INAA); (iii) induction-coupled plasma mass-spectrometry (ICP-MS). Comparison of the results obtained is accompanied by statistical tests and shows that, due to its high sensitivity, simplicity, and non-destructive nature, SR-XFA can be recommended as a method of choice in the search of geochemical signals of changing palaeoclimates.

Study of the Contamination and Absorption of Sr$sup 90$ AND Cs$sup 137$Cs by Prochilodus Platensis (Sabalo). Report No. 31; ESTUDIO DE LA CONTAMINACION Y ABSORCION DEL $sup 90$Sr Y $sup 137$Cs POR EL PROCHILODUS PLATENSIS (SABALO). INFORME NO. 31

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

Anghileri, L.J.

1960-01-01

BS>Contaminatibn and Absorption of Sr/sup 90/ and Cs/sup 137/ by Prochilodus lineatus or platensis (sabalo) is studied. A contamination of its "habitat'' (Rio de la Plata) would create health problems because of the industrialization along the river and use of the water for purposes related to the biological cycle. The distribution of the elements in various organs and tissues of the fish was determined. The results were compared with those obtained by other workers. (J.S.R.)

Isotopic geochemistry of Panama rivers

USGS Publications Warehouse

Harmon, Russell S.; Worner, Gerhard; Pribil, Michael; Kern, Zoltan; Forizs, Istvan; Lyons, W. Berry; Gardner, Christopher B.; Goldsmith, Steven T.

2015-01-01

River water samples collected from 78 watersheds rivers along a 500-km transect across a Late Cretaceous-Tertiary andesitic volcanic arc terrane in west-central Panama provide a synoptic overview of riverine geochemistry, chemical denudation, and CO2 consumption in the tropics. D/H and 18O/16O relationships indicate that bedrock dissolution of andesitic arc crust in Panama is driven by water-rock interaction with meteoric precipitation as it passes through the critical zone, with no evidence of a geothermal or hydrothermal input. Sr-isotope relationships suggest a geochemical evolution for Panama riverine waters that involves mixing of bedrock pore water with water having 87Sr/86Sr ratios between 0.7037-0.7043 and relatively high Sr-contents with waters of low Sr content that enriched in radiogenic Sr that are diluted by infiltrating rainfall to variable extents.

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.

Effect of experimental variables onto Co(2+) and Sr(2+) sorption behavior in red mud-water suspensions.

PubMed

Milenković, Aleksandra S; Smičiklas, Ivana D; Šljivić-Ivanović, Marija Z; Živković, Ljiljana S; Vukelić, Nikola S

2016-07-02

The prospects of rinsed red mud (alumina production residue) utilization for liquid radioactive waste treatment have been investigated, with Co(2+) and Sr(2+) as model cations of radioactive elements. To evaluate the sorption effectiveness and corresponding binding mechanisms, the process was analyzed in batch conditions, by varying experimental conditions (pH, Co(2+) and Sr(2+) concentrations in single solutions and binary mixtures, contact time, and the concentration of competing cations and ligands common in liquid radioactive waste). Comparison of the Co(2+) and Sr(2+) sorption pH edges with the red mud isoelectric point has revealed that Co(2+) removal took place at both positive and negative red mud surface, while Sr(2+) sorption abruptly increased when the surface became negatively charged. The increase of initial cation content and pH resulted in increased equilibrium times and sorption capacity and decreased rate constants. From single metal solutions and various binary mixtures, Co(2+) was sorbed more efficiently and selectively than Sr(2+). While Sr(2+) sorption was reduced by coexisting cations in the order Al(3+) ≥ Ca(2+) >Na(+) ≥Cs(+), removal of Co(2+) was affected by Al(3+) species and complexing agents (EDTA and citrate). Desorption of Co(2+) was negligible in Ca(2+) and Sr(2+) containing media and in solutions with initial pH 4-7. Sr(2+) desorption was generally more pronounced, especially at low pH and in the presence of Co(2+). Collected macroscopic data signify that Co(2+) sorption by red mud minerals occurred via strong chemical bonds, while Sr(2+) was retained mainly by weaker ion-exchange or electrostatic interactions. Results indicate that the rinsed red mud represent an efficient, low-cost sorbent for Co(2+) and Sr(2+) immobilization.

Structure and properties of strontium-doped phosphate-based glasses

PubMed Central

Abou Neel, Ensanya A.; Chrzanowski, Wojciech; Pickup, David M.; O'Dell, Luke A.; Mordan, Nicola J.; Newport, Robert J.; Smith, Mark E.; Knowles, Jonathan C.

2008-01-01

Owing to similarity in both ionic size and polarity, strontium (Sr2+) is known to behave in a comparable way to calcium (Ca2+), and its role in bone metabolism has been well documented as both anti-resorptive and bone forming. In this study, novel quaternary strontium-doped phosphate-based glasses, containing 1, 3 and 5 mol% SrO, were synthesized and characterized. 31P magic angle spinning (MAS) nuclear magnetic resonance results showed that, as the Sr2+ content is increased in the glasses, there is a slight increase in disproportionation of Q2 phosphorus environments into Q1 and Q3 environments. Moreover, shortening and strengthening of the phosphorus to bridging oxygen distance occurred as obtained from FTIR. The general broadening of the spectral features with Sr2+ content is most probably due to the increased variation of the phosphate–cation bonding interactions caused by the introduction of the third cation. This increased disorder may be the cause of the increased degradation of the Sr-containing glasses relative to the Sr-free glass. As confirmed from elemental analysis, all Sr-containing glasses showed higher Na2O than expected and this also could be accounted for by the higher degradation of these glasses compared with Sr-free glasses. Measurements of surface free energy (SFE) showed that incorporation of strontium had no effect on SFE, and samples had relatively higher fractional polarity, which is not expected to promote high cell activity. From viability studies, however, the incorporation of Sr2+ showed better cellular response than Sr2+-free glasses, but still lower than the positive control. This unfavourable cellular response could be due to the high degradation nature of these glasses and not due to the presence of Sr2+. PMID:18826914

Study on strontium isotope abundance-ratio measurements by using a 13-MeV proton beam

NASA Astrophysics Data System (ADS)

Jeong, Cheol-Ki; Jang, Han; Lee, Goung-Jin

2016-09-01

The Rb-Sr dating method is used in dating Paleozoic and Precambrian rocks. This method measures the 87Rb and the 87Sr concentrations by using thermal ionization mass spectrometry (TIMS) [J. Hefne et al., Inter. J. Phys. Sci. 3(1), 28 (2008)]. In addition, it calculates the initial 87Sr/86Sr ratio to increase the reliability of Rb-Sr dating. In this study, the 87Sr/86Sr ratio was measured by using a 13-MeV proton accelerator. Proton kinetic energies are in the range of tens of megaelectronvolts, and protons have large absorption cross-sections for ( p, n) reactions with most substances. After absorbing a proton with such a high kinetic energy, an element is converted into a nuclide with its atomic number increased by one via nuclear transmutation. These nuclides usually have short half-lives and return to the original state through radioactive decay. When a strontium sample is irradiated with protons, nuclear transmutation occurs; thus, the strontium isotope present in the sample changes to a yttrium isotope, which is an activated radioisotope. Based on this, the 87Sr/86Sr ratio was calculated by analyzing the gamma-rays emitted by each yttrium isotope. The KIRAMS-13 cyclotron at the Cyclotron Center of Chosun University, where 13-MeV protons can be extracted, was utilized in our experiment. The 87Sr/86Sr isotope ratio was computed for samples irradiated with these protons, and the result was similar to the isotope ratio for the Standard Reference Material, i.e., 98.2 ± 3.4%. As part of the analysis, proton activation analyses were performed using 13-MeV protons, and the experimental results of this research suggest a possible approach for measuring the strontium-isotope abundance ratio of samples.

Distribution of Some Rare and Trace Elements in Ice-Rafted Sediments in the Yermak Plateau Area, the Arctic Ocean

NASA Astrophysics Data System (ADS)

Shevchenko, V. P.; Maslov, A. V.; Stein, R.

2017-11-01

The distribution of V, Co, Ni, Sr, Nb and rare earth elements (REE) in ice-rafted sediments (IRS) collected in the Yermak Plateau area (the Arctic Ocean) during cruise ARK-XX/3 of the R/V Polarstern in September 2004 has been analyzed. It was determined that the Nb/V ratio in these IRS has an intermediate value between the average ratio values in suspended particulate matter of the Yenisei and Khatanga rivers and Mesozoic-Cenozoic basalts, on the one hand, and suspended matter of the Ob and Lena rivers and post-Archean Australian Shale (PAAS), on the other hand. The REE distribution demonstrates the same pattern. The IRS data points in Nb-Sr, Ni-Co, and Co-Sr and some other diagrams are close mainly to the average chemical composition of suspended particulate matter of the Ob and Lena rivers, i.e., waterways draining watersheds composed predominantly of sedimentary rocks. The Nb, Sr, Ni, and Co contents in the studied IRS samples are close to those in the PAAS. In accordance with this, we were able to conclude that the main provenance areas of the studied IRS samples are situated in the eastern part of the Laptev Sea and the East Siberian Sea, on shelf of which the erosion products of sedimentary and metamorphic rocks of the Verkhoyansk Fold Belt dominate.

Redistribution of Sr and rare earth elements in the matrices of CV3 carbonaceous chondrites during aqueous alteration in their parent body

NASA Astrophysics Data System (ADS)

Jogo, Kaori; Ito, Motoo; Nakamura, Tomoki; Kobayashi, Sachio; Lee, Jong Ik

2018-03-01

We measured the abundances of Sr and rare earth elements (REEs) in the matrices of five CV3 carbonaceous chondrites: Meteorite Hills (MET) 00430, MET 01070, La Paz ice field (LAP) 02206, Asuka (A) 881317 and Roberts Massif (RBT) 04143. In the MET 00430 and MET 01074 matrices, the Sr/CI and light REE (LREE, La-Nd)/CI ratios positively correlate with the amounts of Ca-rich secondary minerals, which formed during aqueous alteration in the CV3 chondrite parent body. In contrast, in the LAP 02206 and RBT 04143 matrices, although the Sr/CI ratios correlate with the amounts of Ca-rich secondary minerals, the LREE/CI ratios vary independently from the amounts of any secondary minerals. This suggests that the LREE/CI ratios in these matrices were produced prior to the parent body alteration, probably in the solar nebula. The LREE/CI ratios of the LAP 02206 and RBT 04143 matrices reveal the mixing process of matrix minerals prior to the accretion of the CV3 chondrite parent body. The mixing degrees of matrix minerals might be different between these two matrices. Because solid materials would be mixed over time according to the radial diffusion model of a turbulent disk, the matrix minerals consisting of LAP 02206 and RBT 04143 matrices might be incorporated into their parent body with different timing.

Do Strontium Isotope Ratios of Animal Bone and Teeth Really Reflect the Isotope Ratios of its birth- and growth-places?

NASA Astrophysics Data System (ADS)

Minami, M.; Goto, A.; Suzuki, K.; Kato, T.; Watanabe, K.; Hasegawa, T.

2007-12-01

Strontium enters the human body through the food chain as nutrients pass from bedrock through soil and water to plants and animals. Strontium substitutes for calcium in the hydroxyapatite mineral of skeletal tissue, and is stored there. 87Sr/86Sr ratios in an individual's bone and teeth could directly reflect the isotopic ratios found in the plants and animals that she or he consumed, which reflect the isotope ratios found in the soil and bedrock of that geologic region. Therefore, 87Sr/86Sr ratios of human skeletons could be useful tools for assessing human residential mobility in prehistory, and many studies on them have been often made. In this study, to evaluate whether the 87Sr/86Sr ratio of a bone or teeth really reflects the isotopic ratios of its birth and growth places, several bone and teeth samples were measured for 87Sr/86Sr ratios, compared with 87Sr/86Sr ratios of geological samples in their growth-places. Bone and teeth samples were leached with 5% acetic acid. After drying, samples were ashed in a muffle furnace at 825°C for 8h, and then digested in nitric acid, followed by cation exchange chromatography with 2.4M hydrochloric acid. 87Sr/86Sr ratios were measured using a thermal ionization mass Spectrometer (VG Sector 54) or an inductively coupled plasma mass spectrometer (Finnigan ELEMENT2). A modern boar bone collected at Asuke, Toyota City, Aichi prefecture, Japan showed a 87Sr/86Sr of 0.71001±0.00002 (2 σ), while stream sediments in the Asuke area showed around 0.710 (Asahara et al., 2006). The 87Sr/86Sr ratio of a modern black bass bone collected from Lake Biwa, Shiga prefecture, Japan was 0.71215±0.00002, while those of surface water in Lake Biwa was 0.71233±0.00002. The similar 87Sr/86Sr ratios between bone and its provenance geology could indicate that the 87Sr/86Sr ratios of bones reflect the isotopic ratios of the birth- and growth-places. The more results of modern and fossil skeletons will be shown in our presentation.

Harvest locations of goose barnacles can be successfully discriminated using trace elemental signatures

NASA Astrophysics Data System (ADS)

Albuquerque, Rui; Queiroga, Henrique; Swearer, Stephen E.; Calado, Ricardo; Leandro, Sérgio M.

2016-06-01

European Union regulations state that consumers must be rightfully informed about the provenance of fishery products to prevent fraudulent practices. However, mislabeling of the geographical origin is a common practice. It is therefore paramount to develop forensic methods that allow all players involved in the supply chain to accurately trace the origin of seafood. In this study, trace elemental signatures (TES) of the goose barnacle Pollicipes pollicipes, collected from ten sites along the Portuguese coast, were employed to discriminate individual’s origin. Barium (Ba), boron (B), cadmium (Cd), chromium (Cr), lithium (Li), magnesium (Mg), manganese (Mn), phosphorous (P), lead (Pb), strontium (Sr) and zinc (Zn) - were quantified using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Significant differences were recorded among locations for all elements. A regularized discriminant analysis (RDA) revealed that 83% of all individuals were correctly assigned. This study shows TES can be a reliable tool to confirm the geographic origin of goose barnacles at fine spatial resolution. Although additional studies are required to ascertain the reliability of TES on cooked specimens and the temporal stability of the signature, the approach holds great promise for the management of goose barnacles fisheries, enforcement of conservation policies and assurance in accurate labeling.

Inhibition of hydrogen sulfide on the proliferation of vascular smooth muscle cells involved in the modulation of calcium sensing receptor in high homocysteine

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

Wang, Yuwen; Wang, Xiyao; Liang, Xiaohui

Hyperhomocysteinemia induces the proliferation of vascular smooth muscle cells (VSMCs). Hydrogen sulfide (H{sub 2}S) inhibits the phenotype switch of VSMCs and calcium-sensing receptor (CaSR) regulated the production of endogenous H{sub 2}S. However, whether CaSR inhibits the proliferation of VSMCs by regulating the endogenous cystathionine-gamma-lyase (CSE, a major enzyme that produces H{sub 2}S) pathway in high homocysteine (HHcy) has not been previously investigated. The intracellular calcium concentration, the concentration of H{sub 2}S, the cell viability, the proliferation and the expression of proteins of cultured VSMCs from rat thoracic aortas were measured, respectively. The results showed that the [Ca{sup 2+}]{sub i} andmore » the expression of p-CaMK and CSE increased upon treatment with CaSR agonist. In HHcy, the H{sub 2}S concentration decrease, the proliferation and migration rate increased, the expression of Cyclin D1, PCNA, Osteopontin and p-Erk1/2 increased while the α-SM actin, P21{sup Cip/WAK−1} and Calponin decreased. The CaSR agonist or exogenous H{sub 2}S significantly reversed the changes of VSMCs caused by HHcy. In conclusion, our results demonstrated that CaSR regulate the endogenous CSE/H{sub 2}S is related to the PLC-IP{sub 3} receptor and CaM signal pathways which inhibit the proliferation of VSMCs, and the latter is involved in the Erk1/2 dependent signal pathway in high homocysteine. - Highlights: • CaSR activation increased the production of endogenous H{sub 2}S in high homocysteine VSMCs. • CaSR modulated the CSE/H{sub 2}S are related to the PLC-IP{sub 3}R and Ca{sup 2+}-CaM signal pathways. • Inhibition of H{sub 2}S on the proliferation of VSMCs is involved in the Erk1/2 pathway. • Explore the potential roles of CaSR in regulating VSMCs proliferation in high homocysteine.« less

Thermoelectric La-doped SrTiO3 epitaxial layers with single-crystal quality: from nano to micrometers

NASA Astrophysics Data System (ADS)

Apreutesei, Mihai; Debord, Régis; Bouras, Mohamed; Regreny, Philippe; Botella, Claude; Benamrouche, Aziz; Carretero-Genevrier, Adrian; Gazquez, Jaume; Grenet, Geneviève; Pailhès, Stéphane; Saint-Girons, Guillaume; Bachelet, Romain

2017-12-01

High-quality thermoelectric La0.2Sr0.8TiO3 (LSTO) films, with thicknesses ranging from 20 nm to 0.7 μm, have been epitaxially grown on SrTiO3(001) substrates by enhanced solid-source oxide molecular-beam epitaxy. All films are atomically flat (with rms roughness < 0.2 nm), with low mosaicity (<0.1°), and present very low electrical resistivity (<5 × 10-4 Ω cm at room temperature), one order of magnitude lower than standard commercial Nb-doped SrTiO3 single-crystalline substrate. The conservation of transport properties within this thickness range has been confirmed by thermoelectric measurements where Seebeck coefficients of approximately -60 μV/K have been recorded for all films. These LSTO films can be integrated on Si for non-volatile memory structures or opto-microelectronic devices, functioning as transparent conductors or thermoelectric elements.

DEPENDENCE OF THE Sr-TO-Ba AND Sr-TO-Eu RATIO ON THE NUCLEAR EQUATION OF STATE IN METAL-POOR HALO STARS

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

Famiano, M. A.; Kajino, T.; Aoki, W.

A model is proposed in which the dependence on the equation of state (EOS) of the scatter of [Sr/Ba] in metal-poor stars is studied. Light r-process element enrichment in these stars has been explained via a truncated r-process, or “tr-process.” The truncation of the r-process from a generic core-collapse event followed by a collapse into an accretion-induced black hole is examined in the framework of a galactic chemical evolution model. The constraints on this model imposed by observations of extremely metal-poor stars are explained, and the upper limits in the [Sr/Ba] distributions are found to be related to the nuclearmore » EOS in a collapse scenario. The scatter in [Sr/Ba] and [Sr/Eu] as a function of metallicity has been found to be consistent with turbulent ejection in core-collapse supernovae. Adaptations of this model are evaluated to account for the scatter in isotopic observables. This is done by assuming mixing in ejecta in a supernova event. Stiff EOS are eliminated by this model.« less

Pb, Sr, and Nd isotopes in seamount basalts from the Juan de Fuca Ridge and Kodiak-Bowie seamount chain, northeast Pacific

USGS Publications Warehouse

Hegner, E.; Tatsumoto, M.

1989-01-01

Pb, Sr, and Nd isotopic ratios and their parent/daughter element concentrations for 28 basalts from 10 hotspot and nonhotspot seamounts are reported. Nd and Sr isotopic compositions (143Nd/144Nd = 0.51325-0.51304; 87Sr/86Sr = 0.70237-0.70275) plot in the envelope for Juan de Fuca-Gorda ridge basalts with tholeiitic basalts showing more depleted sources and a better negative correlation than transitional to alkalic basalts. Pb isotopic ratios in tholeiitic and alkalic basalts overlap (206Pb/204Pb = 18.29-19.44) and display a trend toward more radiogenic Pb in alkalic basalts. The isotopic data for hotspot and nonhotspot basalts are indistinguishable and correlate broadly with rock composition, implying that they are controlled by partial melting. The isotopic variation in the seamount basalts is about 60% (Nd-Sr) to 100% (Pb) of that in East Pacific Rise basalts and is interpreted as a lower limit for the magnitude of mantle heterogeneity in the northeast Pacific. The data indicate absence of a chemically distinct plume component in the linear seamount chains and strongly suggest an origin from mid-ocean ridge basalt-like east Pacific mantle. -Authors

Effect of Varying Pnictogen Elements (Pn=N, P, As, Sb, Bi) on the Optoelectronic Properties of SrZn2Pn2

NASA Astrophysics Data System (ADS)

Murtaza, G.; Yousaf, N.; Laref, A.; Yaseen, M.

2018-03-01

Pnictogen-based Zintl compounds have fascinating properties. Nowadays these compounds have gained exceptional interest in thermoelectric and optoelectronic fields. Therefore, in this work the structural, electronic and optical properties of SrZn2Pn2 (Pn=N, P, As, Sb, Bi) compounds were studied using state-of-the-art density functional theory. The optimised lattice parameters (ɑ, c, c/ɑ and bond lengths) are consistent with the experimental results. The bulk moduli and c/a showed a decrease when changing the Pnictogen (Pn) anion from N to Bi in SrZn2Pn2 (Pn=N, P, As, Sb, Bi). The modified Becke-Johnson potential is used for band structure calculations. All compounds show semiconducting behaviour except SrZn2Bi2, which is metallic. Pn-p, Zn-d and Sr-d play an important role in defining the electronic structure of the compounds. The optical conductivity and absorption coefficient strength are high in visible and ultraviolet regions. These band structures and optical properties clearly show that SrZn2Pn2 compounds are potential candidates in the fields of optoelectronic and photonic devices.

Phase stability and B-site ordering in La{sub 2}NiMnO{sub 6} thin films

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

Jin, Xiao-Wei; Lu, Lu; Liu, Ming

2016-07-18

Thin films of multiferroic double-perovskite La{sub 2}NiMnO{sub 6} are prepared on (001)-oriented SrTiO{sub 3}, (La{sub 0.289}Sr{sub 0.712})(Al{sub 0.633}Ta{sub 0.356})O{sub 3}, and LaSrAlO{sub 4} substrates by pulsed laser deposition. Microstructure investigation by advanced electron microscopy shows that the La{sub 2}NiMnO{sub 6} films have a monoclinic structure on the SrTiO{sub 3} substrates and a rhombohedral structure on the (La{sub 0.289}Sr{sub 0.712})(Al{sub 0.633}Ta{sub 0.356})O{sub 3} and LaSrAlO{sub 4} substrates. Atomic-scale elemental maps of the monoclinic and rhombohedral phases reveal a short-range and/or partial ordering of the B-sites. In addition, domains and columnar grains are found in the films. Our results demonstrate that themore » phase and microstructure of the La{sub 2}NiMnO{sub 6} films can be tuned by epitaxial strains induced by different substrates.« less

Post-collisional magmatism in the Late Miocene Rodna-Bârgău district (East Carpathians, Romania): Geochemical constraints and petrogenetic models

NASA Astrophysics Data System (ADS)

Fedele, Lorenzo; Seghedi, Ioan; Chung, Sun-Lin; Laiena, Fabio; Lin, Te-Hsien; Morra, Vincenzo; Lustrino, Michele

2016-12-01

Post-collisional magmatism in the Late Miocene Rodna-Bârgău subvolcanic district (East Carpathians) gave rise to a wide variety of rock compositions, allowing recognition of four groups of calcalkaline rocks with distinctive petrography, mineral chemistry, whole-rock geochemistry and Sr-Nd-Hf isotope features. New U-Pb zircon datings, together with literature data, indicate that the emplacement of the four rock groups was basically contemporaneous in the 11.5-8 Ma time span. The low potassium group (LKG) includes the most abundant lithotypes of the area, ranging from basaltic andesite to dacite, characterized by K-poor tschermakitic amphibole, weak enrichment in LILE and LREE, relatively low 87Sr/86Sr, coupled with relatively high 143Nd/144Nd and 176Hf/177Hf. The high potassium group (HKG) includes amphibole-bearing microgabbro, amphibole andesite and amphibole- and biotite dacite, with K-richer magnesio-hastingsite to hastingsite amphibole, more marked enrichments in incompatible elements, higher 87Sr/86Sr and lower 143Nd/144Nd and 176Hf/177Hf. These two main rock groups seem to have originated from similar juxtaposed mantle sources, with the HKG possibly related to slightly more enriched domains (with higher H2O reflected by the higher modal amphibole) with respect to LKG (with higher plagioclase/amphibole ratios). The evolution of the two rock series involved also open-system processes, taking place mainly in the upper crust for the HKG, in the lower crust for LKG magmas. In addition, limited occurrences of generally younger strongly evolved peraluminous rhyolites and microgranites (Acid group) and sialic-dominated "leucocratic" andesites and dacites (LAD group) were also recognized to the opposite outermost areas of the district. These two latter rock groups were generated by the melting of a basic metamorphic crustal source (respectively in hydrous and anhydrous conditions), favored by the heat released by mantle melts from the adjoining central area. The peculiar distribution of the products of the four rock groups in well defined sectors argues for a strong control of the local crustal tectonic regime on magmatism, influenced by the change from a transpressional to trastensional stage.

The Role of Twelve-Step-Related Spirituality in Addiction Recovery.

PubMed

Dermatis, Helen; Galanter, Marc

2016-04-01

This paper reviews empirical studies conducted on the role of spirituality and religiosity (S/R) characteristics in 12-step recovery among program members followed up after substance abuse treatment and those assessed independent of formal treatment. Aspects of spiritual functioning that change in relation to program participation and those S/R characteristics that were found to mediate the association between program involvement and drinking-related outcomes are discussed. In addition, a review is provided of 12-step program studies investigating S/R-related predictors of clinical outcomes relevant to risk of relapse among members in long-term recovery. To further examine the role of S/R characteristics in recovery, a study was conducted on long-term AA members to assess the relationship of S/R characteristics and AA program involvement to craving for alcohol and emotional distress after controlling for relevant demographic variables. Feeling God's presence daily, believing in a higher power as a universal spirit, and serving as an AA sponsor were all predictive of positive outcomes.

Strontium isotope fractionation during strontianite (SrCO3) dissolution, precipitation and at equilibrium

NASA Astrophysics Data System (ADS)

Mavromatis, Vasileios; Harrison, Anna L.; Eisenhauer, Anton; Dietzel, Martin

2017-12-01

In this study we examine the behavior of stable Sr isotopes between strontianite [SrCO3] and reactive fluid during mineral dissolution, precipitation, and at chemical equilibrium. Experiments were performed in batch reactors at 25 °C in 0.01 M NaCl solutions wherein the pH was adjusted by bubbling of a water saturated gas phase of pure CO2 or atmospheric air. The equilibrium Sr isotope fractionation between strontianite and fluid after dissolution of the solid under 1 atm CO2 atmosphere was estimated as Δ88/86SrSrCO3-fluid = δ88/86Sr SrCO3 - δ88/86Srfluid = -0.05 ± 0.01‰. On the other hand, during strontianite precipitation, an enrichment of the fluid phase in 88Sr, the heavy isotopomer, was observed. The evolution of the δ88/86Srfluid during strontianite precipitation can be modeled using a Rayleigh distillation approach and the estimated, kinetically driven, fractionation factor αSrCO3-fluid between solid and fluid is calculated to be 0.99985 ± 0.00003 corresponding to Δ88/86SrSrCO3-fluid = -0.15‰. The obtained results further support that under chemical equilibrium conditions between solid and fluid a continuous exchange of isotopes occurs until the system approaches isotopic equilibrium. This isotopic exchange is not limited to the outer surface layer of the strontianite crystal, but extends to ∼7-8 unit cells below the crystal surface. The behavior of Sr isotopes in this study is in excellent agreement with the concept of dynamic equilibrium and it suggests that the time needed for achievement of chemical equilibrium is generally shorter compared to that for isotopic equilibrium. Thus it is suggested that in natural Sr-bearing carbonates an isotopic change may still occur close to thermodynamic equilibrium, despite no observable change in aqueous elemental concentrations. As such, a secondary and ongoing change of Sr isotope signals in carbonate minerals caused by isotopic re-equilibration with fluids has to be considered in order to use Sr isotopes as environmental proxies in aquatic environments.

Film growth and structure design in the barium oxide-strontium oxide-titanium dioxide system

NASA Astrophysics Data System (ADS)

Fisher, Patrick J.

This thesis describes the growth and characterization of thin films in the SrO-BaO-TiO2 system. The films are grown by molecular beam cpitaxy (MBE) and pulsed laser deposition (PLD) on ceramic substrates, and characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), reflection-high energy electron diffraction (RHEED), and transmission electron microscopy (TEM). Films are grown with varied global and initial local stoichiometries, with the goal of determining the stability of specific cation organizations. Simple oxides, TiO2 (anatase) and SrO (rock salt) were grown on oxide substrates using MBE. Growth conditions, including substrate material, substrate temperature, O3 flux, and metal flux, are varied in each case. It is observed that the growth morphology of anatase is highly dependent on the ozone flux, with fluxes of 1.00 sccm and greater resulting in flat anatase surfaces. Increased roughness at higher substrate was determined to be a result of rutile inclusions. Growth oscillations are observed in the RHEED intensity for both TiO2 and SrO in overlapping regions of growth space, indicating 2D growth modes. Varied shuttering sequences were used during MBE growth of perovskites: globally non-stoichiometric films, as well as locally non-stoichiometric but globally stoichiometric perovskite. Films were grown within a (SrO) m(TiO2)n framework, where growth cycles involved m monolayers of SrO followed by n monolayers of TiO2. XRD results indicate that Ruddlesden-Popper defects, that is, rock salt double layers, enable incorporation of all levels of Sr excess, whereas excess Ti is observed to incorporate into the perovskite structure only at extreme excesses. A series of films with m equal to n were grown; that is, multiple monolayers of SrO deposited followed by multiple monolayers of TiO2. These initially locally non-stoichiometric arrangements interreact to form highly crystalline perovskite, even with layer thicknesses of up to 33 monolayers. The Ba0.6Sr0.4TiO3 films were characterized for their microwave dielectric properties, and were found to have high dielectric constants (epsilonr ˜1300 in each case, implying high tunabilities) but high tan delta values as well. The mechanisms by which the perovskite structure incorporates cation excesses is discussed, and it is argued that two probable mechanisms, one involving plane-sharing of Ti and Sr cations and the other involving rock salt multilayers, also enable the observed transport necessary for multilayer reaction. Working under the argument that these mechanisms involve low-energy architectures, a novel homologous series of phases based on rock salt multilayers is grown using monotayer control: the SrmTiO2+ m series, with each TiO2 monolayer followed by m SrO monolayers (m = 1-5). The phases in this series were characterized structurally, and an in-plane contraction was observed between the m = 2 and m = 3 phases, which is argued to be a relaxation of the SrO monolayers. Considering Ti-excess organizations, the BaTi2O5 structure is grown and observed to nucleate over a narrow window of growth conditions and substrates. LaAlO 3(100) promotes the nucleation of anatasc and ejection of perovskite; SrTiO3(100) promotes the nucleation of perovskite and ejection of TiO2; importantly, MgO(100) promotes the nucleation (010)-oriented BaTi2O5 growing with multiple domains. A BaTi2 O5 buffer layer was then used to promote the inclusion of Sr into (Ba,SOTi205 epilayers. Sr incorporation into a perovskite-related structure was observed to occur over the full range of (Ba,Sr)Ti2O 5 compositions.

The magmatic evolution and genesis of the Quaternary basanite-trachyphonolite suite of Itasy (Madagascar) as inferred by geochemistry, Sr-Nd-Pb isotopes and trace element distribution in coexisting phases

NASA Astrophysics Data System (ADS)

Melluso, L.; Tucker, R. D.; Cucciniello, C.; le Roex, A. P.; Morra, V.; Zanetti, A.; Rakotoson, R. L.

2018-06-01

The Itasy is a Pleistocene-Holocene volcanic field in central Madagascar, located to the west of the Ankaratra volcanic complex. It comprises scoria cones and lava domes (>120), with associated pyroclastic fall and mafic lava flows, covering an area of ab. 400 km2. The last volcanic episodes probably dated ca. 6000-7100 y BP; warm springs and geysers are active. The juvenile samples comprise a peculiar, almost bimodal, rock suite ranging from potassic leucite-kaersutite-bearing basanites, tephrites and phonotephrites, to benmoreites and titanite-haüyne-bearing trachyphonolites (MgO from 9-10 wt% to 0.1 wt%). These rocks show continuous and overlapping variations in the bulk-rock and phase composition (olivine, clinopyroxene, amphibole, feldspar, leucite, haüyne, nepheline, oxides, apatite, titanite, glass and other accessories). The basanites have homogeneous isotopic composition (87Sr/86Sr = 0.70366-0.70378, 143Nd/144Nd = 0.51274-0.51277, 206Pb/204Pb = 18.7-18.9, 207Pb/204Pb = 15.53-15.56; 208Pb/204Pb = 38.89-39.01), and a marked enrichment in the most incompatible elements (LILE and HFSE reach 100-215 times primitive mantle). These features are consistent with low degrees of partial melting of a volatile-, LILE- and HFSE-rich, amphibole-bearing peridotitic mantle induced by uplift during an E-W-directed extensional regime, as is found in central Madagascar. The marked changes in the geochemical composition, and small variations of the Sr-Nd-Pb isotopes in the trachyphonolites (87Sr/86Sr = 0.70425-0.70446, 143Nd/144Nd = 0.51266-0.51269, 206Pb/204Pb = 18.18-18.39, 207Pb/204Pb = 15.49-15.51; 208Pb/204Pb = 38.38-39.57) with respect to basanites and tephrites point to a limited amount of crustal contamination by the relatively low-206Pb/204Pb, low-143Nd/144Nd, high-87Sr/86Sr Precambrian basement rocks (of Middle Archean to Late Proterozoic age), and highlight the geochemical effects of titanite and anorthoclase removal on the trace element fractionation trends, a feature also shown in the trace element composition of the phenocrysts in trachyphonolites. Supplementary Table S2: synopsis of the mineral assemblages of the main lithotypes of the Itasy complex. Supplementary Table S3: composition of olivine of the Itasy rocks. Supplementary Table S4: composition of oxides of the Itasy rocks. Supplementary Table S5: composition of pyroxene of the Itasy rocks. Supplementary Table S6: composition of amphibole, biotite and rhönite of the Itasy rocks. Supplementary Table S7: composition of feldspar and glass of the Itasy rocks. Supplementary Table S8: composition of feldspathoids of the Itasy rocks. Supplementary Table S9: composition of titanite, apatite, other accessories of the Itasy rocks. Supplementary Table S10: Recapitulation of mass balance calculations between rocks of different degree of magmatic evolution, and detailed results. The composition of the phases is reported in the supplementary tables. Supplementary Table S11: average REE mineral/bulk rock ratios for titanite, amphibole and clinopyroxene. The partition coefficients of titanite, clinopyroxene, apatite and amphibole are taken from Olin and Wolff (2012), Fedele et al. (2009, 2015) and Tiepolo et al. (2007). Note that amphibole of RT-06I-355 could not be considered in equilibrium with the host rock (cf. Supplementary Figs. S1a, S1b, S1c).

HOW MANY NUCLEOSYNTHESIS PROCESSES EXIST AT LOW METALLICITY?

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

Hansen, C. J.; Montes, F.; Arcones, A., E-mail: cjhansen@lsw.uni-heidelberg.de, E-mail: cjhansen@dark-cosmology.dk, E-mail: montes@nscl.msu.edu, E-mail: almudena.arcones@physik.tu-darmstadt.de

Abundances of low-metallicity stars offer a unique opportunity to understand the contribution and conditions of the different processes that synthesize heavy elements. Many old, metal-poor stars show a robust abundance pattern for elements heavier than Ba, and a less robust pattern between Sr and Ag. Here we probe if two nucleosynthesis processes are sufficient to explain the stellar abundances at low metallicity, and we carry out a site independent approach to separate the contribution from these two processes or components to the total observationally derived abundances. Our approach provides a method to determine the contribution of each process to themore » production of elements such as Sr, Zr, Ba, and Eu. We explore the observed star-to-star abundance scatter as a function of metallicity that each process leads to. Moreover, we use the deduced abundance pattern of one of the nucleosynthesis components to constrain the astrophysical conditions of neutrino-driven winds from core-collapse supernovae.« less

Spectroscopic, Elemental and Thermal Analysis, and Positron Annihilation Studies on Ca(II), Sr(II), Ba(II), Pb(II), and Fe(III) Penicillin G Potassium Complexes

NASA Astrophysics Data System (ADS)

Refat, M. S.; Sharshara, T.

2015-11-01

The [Pb(Pin)2] · 3H2O, [M(Pin)(H2O)2(Cl)] · nH2O (M = SrII, CaII or BaII; n = 0-1), and [Fe(Pin)2(Cl)(H2O)] · H2O penicillin G potassium (Pin) complexes were synthesized and characterized using elemental analyses, molar conductivity, thermal analysis and electronic spectroscopy techniques. The positron annihilation lifetime (PAL) and Doppler broadening (DB) techniques have been employed to probe the defects and structural changes of Pin ligand and its complexes. The PAL and DB line-shape parameters were discussed in terms of the structure, molecular weight, ligand-metal molar ratio, and other properties of the Pin complexes.

Distribution and Phase Association of Some Major and Trace Elements in the Arabian Gulf Sediments

NASA Astrophysics Data System (ADS)

Basaham, A. S.; El-Sayed, M. A.

1998-02-01

Twenty-four sediment samples were collected from the Arabian Gulf (ROPME Sea) and analysed for their grain size distribution and carbonate contents as well as the major elements Ca, Mg, Fe and Al and macro and trace elements Mn, Sr, Ba, Zn, Cu, Cr, V, Ni and Hg. Concentration of trace elements are found comparable to previous data published for samples taken before and after the Gulf War, and reflect the natural background level. Grain size analyses, aluminium and carbonate measurements support the presence of two major sediment types: (1) a terrigenous, fine-grained and Al rich type predominating along the Iranian side; and (2) a coarse-grained and carbonate rich type predominating along the Arabian side of the Gulf. Investigation of the correlation of the elements analysed with the sediment type indicates that they could be grouped under two distinct associations: (1) carbonate association including Ca and Sr; and (2) terrigenous association comprising Al, Fe, Mg, Ba, Mn, Zn, Cu, Cr, V, Ni and Hg. Element/Al ratios calculated for the mud non-carbonate fraction indicate that the Euphrates and Tigris rivers have minor importance as sediment sources to the Gulf. Most of the elements have exceptionally high aluminium ratios in sediments containing more than 85-90% carbonate. These sediments are restricted to the southern and south-eastern part of the area where depth is shallow and temperature and salinity are high. Both biological accumulation and chemical and biochemical coprecipitation could be responsible for this anomaly.

Genesis of ultra-high pressure garnet pyroxenites in orogenic peridotites and its bearing on the compositional heterogeneity of the Earth's mantle

NASA Astrophysics Data System (ADS)

Varas-Reus, María Isabel; Garrido, Carlos J.; Marchesi, Claudio; Bosch, Delphine; Hidas, Károly

2018-07-01

We present an integrated geochemical study of ultra-high pressure (UHP) garnet pyroxenites from the Ronda and Beni Bousera peridotite massifs (Betic-Rif Belt, westernmost Mediterranean). Based on their Sr-Nd-Pb-Hf isotopic systematics, we classify UHP garnet pyroxenites into three groups: Group A pyroxenites (Al2O3: 15-17.5 wt.%) have low initial 87Sr/86Sr, relatively high εNd, εHf and 206Pb/204Pb ratios, and variable 207Pb/204Pb and 208Pb/204Pb. Group B pyroxenites (Al2O3 < 14 wt.%) are characterized by high initial 87Sr/86Sr and relatively low εNd, εHf and 206Pb/204Pb ratios. Group C pyroxenites (Al2O3 ∼ 15 wt.%) have depleted radiogenic signatures with relatively low initial 87Sr/86Sr and 206Pb/204Pb, high εNd and εHf, and their 207Pb/204Pb and 208Pb/204Pb ratios are similar to those of Group B pyroxenites. The major and trace element and isotopic compositions of UHP garnet pyroxenites support their derivation from ancient (1.5-3.5 Ga) oceanic crust recycled into the mantle and intimately stirred with peridotites by convection. However, the genesis of these pyroxenites requires also the involvement of recycled continental lower crust with an isotopic composition akin to the lower crustal section of the lithosphere where these UHP garnet pyroxenites now reside in. These oceanic and continental crustal components were stirred in different proportions in the convective mantle, originating pyroxenites with a more marked geochemical imprint of either oceanic (Group A) or continental lower crust (Group B), or hybrid compositions (Group C). The pyroxenite protoliths likely underwent several melting events, one of them related to the formation of the subcontinental lithospheric mantle and continental crust, generating restitic UHP garnet pyroxenites now preserved in the Ronda and Beni Bousera orogenic peridotites. The extent of melting was mostly controlled by the bulk Mg-number (Mg#) of the pyroxenite protoliths, where protoliths with low Mg# experienced higher degrees of partial melting than sources with higher Mg#. Positive Eu and Sr anomalies in bulk rocks, indicative of their origin from cumulitic crustal gabbros, are preserved mostly in high Mg# pyroxenites due to their higher melting temperatures and consequent lower partial melting degrees. The results of this study show that the genesis of UHP garnet pyroxenites in orogenic peridotites requires a new recipe for the marble cake mantle hypothesis, combining significant recycling and stirring of both oceanic and continental lower crust in the Earth's mantle. Furthermore, this study establishes a firm connection between the isotopic signatures of UHP pyroxenite heterogeneities in the mantle and the continental lower crust.

First-principles study of codoping in lanthanum bromide

NASA Astrophysics Data System (ADS)

Erhart, Paul; Sadigh, Babak; Schleife, André; Åberg, Daniel

2015-04-01

Codoping of Ce-doped LaBr3 with Ba, Ca, or Sr improves the energy resolution that can be achieved by radiation detectors based on these materials. Here, we present a mechanism that rationalizes this enhancement on the basis of first-principles electronic structure calculations and point defect thermodynamics. It is shown that incorporation of Sr creates neutral VBr-SrLa complexes that can temporarily trap electrons. As a result, Auger quenching of free carriers is reduced, allowing for a more linear, albeit slower, scintillation light yield response. Experimental Stokes shifts can be related to different CeLa-SrLa-VBr triple complex configurations. Codoping with other alkaline as well as alkaline-earth metals is considered as well. Alkaline elements are found to have extremely small solubilities on the order of 0.1 ppm and below at 1000 K. Among the alkaline-earth metals the lighter dopant atoms prefer interstitial-like positions and create strong scattering centers, which has a detrimental impact on carrier mobilities. Only the heavier alkaline-earth elements (Ca, Sr, Ba) combine matching ionic radii with sufficiently high solubilities. This provides a rationale for the experimental finding that improved scintillator performance is exclusively achieved using Sr, Ca, or Ba. The present mechanism demonstrates that codoping of wide-gap materials can provide an efficient means for managing charge carrier populations under out-of-equilibrium conditions. In the present case dopants are introduced that manipulate not only the concentrations but also the electronic properties of intrinsic defects without introducing additional gap levels. This leads to the availability of shallow electron traps that can temporarily localize charge carriers, effectively deactivating carrier-carrier recombination channels. The principles of this mechanism are therefore not specific to the material considered here but can be adapted for controlling charge carrier populations and recombination in other wide-gap materials.

Simultaneous thermodynamic and geochemical analyses for P-T-time and mass transport toward comprehensive understanding of metamorphism

NASA Astrophysics Data System (ADS)

Uno, M.; Nakamura, H.; Iwamori, H.

2011-12-01

Individual parcel of regional metamorphic rock records physico-chemical conditions such as P-T path, mass transfer and deformation with the Lagrangian specification. On the other hand, a metamorphic belt as an ensemble of such parcels may provide a large-scale flow field of energy (e.g., temperature, entropy) and mass (including both solid and fluid phases with elements and isotopes) with the Eulerian specification. However, there is so far few model that integrates all the variables stated above. Phase petrology provides mostly the intensive variables (e.g., P-T path), whereas geochemistry provides mostly the extensive variables (time-integrated mass transfer), and these two have been treated separately. Here we combine phase petrology and geochemistry from a scale of mineral grain, and solve them under a simultaneous and consistent set of thermodynamic and mass balance equation. For this sake, the Sanbagawa metamorphic belt in Japan has been surveyed. To understand the nature of fluid during rehydration, we analyzed both basic rocks and pelitic rocks that record retrograde reactions. Major and trace element compositions of each mineral, and bulk rock chemistry have been analyzed with EPMA, LA-ICP-MS, XRF and ICP-MS, respectively. Retrograde P-T path and the extent of rehydration of each rock have been obtained by applying the Gibbs' method (e.g. Spear, 1993; Okamoto&Toriumi, 2001) to amphiboles. Trace element budget along a specific P-T path were calculated by equating differential mass balance equation for major and trace elements as follows; XfluiddMfluid = ⊙MsolidXsolid + ⊙XsoliddMsolid Where the X and M denotes compositions and modes of minerals and dX and dM are their changes along a specific P-T change. The mineral compositions (Xsolid), mineral modes (Msolid), mineral growths (dMsolid) for zoned minerals (amphibole and/or garnet) and fluid compositions (Xfluid) were derived from the results of Gibbs' method, X-ray map and fluid/mineral partition coefficients, respectively. Thus, the unknowns are dMs, and the equations are solved for them. As a result, the mass transfer during the specific P-T change (Xfluid dMfluid) can be specified. It is revealed that fluid mobile elements such as LIL elements, Sr and Pb are mostly proportional to LOI (loss on ignition). LOI and extent of rehydration is proportional in the Sanbagawa belt (Okamoto&Toriumi, 2005), thus the observed enrichment of LILE, Sr and Pb are interpreted to be associated with rehydration. The Sr isotope ratios of the basic shists also increase with LOI, implying that the differences in bulk rock chemistry are not attributed to differences in mineral modes,but addition and/or reaction with external source of fluids with high 87Sr/86Sr. The estimated fluid composition is similar to calculated compositions of slab-derived fluids (Nakamura et al., 2008). From mass balance calculation, trace element budget associated with rehydration reactions and their spatial distribution will be presented, and the mechanisms of mass and fluid transfer will be discussed.

Geochemical and tectonic implications on plate-interface evolution achieved from high-pressure ultramafic rocks in mélange settings

NASA Astrophysics Data System (ADS)

Cannaò, E.; Agostini, S.; Scambelluri, M.; Tonarini, S.

2014-12-01

Geochemical studies of fluid-mobile elements (FME) joined with B, Sr and Pb isotopic analyses of high-pressure mélanges terranes help constraining tectonic processes and mass transfer during accretion of slab and suprasubduction mantle in plate-interface domains. Here we focus on ultramafic rocks from two plate interface settings: (I) metasediment-dominated mélange (Cima di Gagnone, CdG, Adula Unit), where eclogite-facies de-serpentinized garnet peridotite and chlorite harzburgite lenses are embedded in paraschist; (II) dominated by high-pressure serpentinite (Erro-Tobbio, ET, and Voltri Units, VU, Ligurian Alps). CdG metaperidotite shows low [B], negative δ 11B and high Sr and Pb isotopic ratios. As, Sb loss from metasediment and gain by garnet and chlorite metaperidotite points to exchange between the two systems. Presence of As and Sb in eclogite-facies peridotite minerals and preferential low-T mobility of such elements suggest that exchange was during early subduction burial and prior to eclogitization. Based on high [B], positive δ11B, oxygen and hydrogen isotope, the ET serpentinties were recently interpreted as supra-subduction mantle flushed by slab fluids (Scambelluri & Tonarini, 2012, Geology, 40, 907-910). Their 206Pb/204Pb and 87Sr/86Sr isotope ratios range between 18.300-18.514 and 0.7048-0.7060, respectively. Compared with ET rocks, VU serpentinites have higher As, Sb (up to 1.3 and 0.39 ppm, respectively) and are enriched in radiogenic Sr (up to 0.7105 87Sr/86Sr). This signature reflects interaction with fluids that exchanged with sedimentary rocks, either in outer rise environments or during accretion atop the slab. In the above cases, the serpentinized mantle rocks fingerprint interaction with fluids from different sources, indicating a timing of accretion to plate interface domains. We provide evidence that serpentinized mantle slices of different size and provenance (slab or wedge) accreted to plate interface domains since early subduction stages. They also represent FME and radiogenic isotope sources for arcs and for deep mantle refertilization.

Lithospheric and Asthenospheric Contributions to Post-Collisional Volcanism in the Lesser Caucasus Mts (Armenia)

NASA Astrophysics Data System (ADS)

Sugden, P.; Savov, I. P.; Wilson, M.; Meliksetian, K.; Navasardyan, G.

2017-12-01

Continental collision zones remain the most enigmatic tectonic setting for volcanic activity on earth. The Lesser Caucasus Mts are host to widespread and unique intraplate volcanism, associated with the active Arabia-Eurasia continental collision. Volcanic products range from alkali basalts to rhyolites (including extensive ignimbrites), and occur as basaltic lava flow fields, large composite and shield volcanoes, and regions of distributed (mostly monogenetic) volcanism. Geomorphology, archaeology, and historical accounts suggest volcanic activity has extended in to the Holocene-historical period. The high quality of the exposures and the diversity of unaltered rock types makes Armenia an ideal natural laboratory for studying the sources of magmatism in an active continental collision zone. For the first time, we will present the mineral chemistry (ol, px, amph), whole rock major and trace element, and Sr-Nd isotope compositions of volcanic rocks from southernmost Armenia- namely the Gegham, Vardenis and Syunik volcanic highlands. We compare our dataset with the composition of post-collisional volcanic rocks elsewhere in the Arabia-Eurasia collision zone. Samples from S. Armenia are more mafic, more alkaline and more K2O rich. All volcanic rocks show negative HFSE anomalies and LILE and LREE enrichments reminiscent of continental volcanic arc settings. However, volcanic rocks in Southern Armenia are further enriched in some of the most incompatible trace elements, most notably LREE, Sr and P, and have higher La/Yb, Th/Yb, Ta/Yb, and more variable Th/Nb. Volcanic rocks from Eastern Anatolia and N. Armenia have Sr-Nd isotope compositions similar to those of the Mesozoic volcanic arc (87Sr/86Sr 0.7034-0.7045; 143Nd/144Nd 0.5128-0.5129), whereas samples from S. Armenia deviate towards more enriched compositions resembling a typical EM-I type reservoir (87Sr/86Sr 0.7041- 0.7047; 143Nd/144Nd 0.5127-0.5128). We argue that these distinctive geochemical characteristics result from the addition of an enriched lithospheric component to a ubiquitous subduction-modified baseline asthenospheric mantle. This EM-I like component may be characteristic for not only intraplate hotspot volcanoes but also to collisional and arc settings.

Contrasting sodic and mildly potassic magma differentiation lineages at The Pleaides volcanic complex, northern Victoria Land, Antarctica

NASA Astrophysics Data System (ADS)

Kim, J.; Park, J. W.; Lee, J.; Kyle, P. R.; Lee, M. J.

2017-12-01

The magma evolution of The Pleiades, a Quaternary alkaline volcanic complex in northern Victoria Land, Antarctica, is investigated using major and trace elements, and Sr, Nd and Pb isotopic data. The volcanic rocks can be subdivided into two distinct magmatic lineages based on petrography and whole-rock compositions: (1) a sodic silica-undersaturated alkaline lineage with abundant kaersutite phenocrysts, and (2) a mildly-potassic and mildly-alkaline, nearly silica-saturated lineage containing olivine but not kaersutite. The basanite and trachybasalt of both lineages exhibit similar degrees of negative K anomalies, moderately steep rare earth element patterns, and elevated trace element ratios such as Ce/Pb (> 20) and Nb/U (> 38), suggesting their primary magmas were generated by low degree (≤3%) of partial melting of amphibole and garnet-bearing mantle sources. The sodic lineage is characterized by elevated 206Pb/204Pb (>19.5) ratios and narrow ranges of 87Sr/86Sr (0.70313-0.70327) and 143Nd/144Nd (0.51289-0.51290) ratios consistent with a significant HIMU component typical of Neogene volcanic rocks in Antarctica. The mafic rocks of the potassic lineage have isotopic compositions similar to those of the sodic lineage, however the evolved lavas in the lineage have higher 87Sr/86Sr (> 0.7035) and lower 143Nd/144Nd (< 0.51285) and 206Pb/204Pb (< 19.3) ratios than the mafic rocks, suggesting significant amounts of crustal contamination. The pressure-temperature paths estimated by clinopyroxene-liquid thermobarometry are similar in each lineage. The mafic magmas were emplaced at Moho depths ( 1.2 GPa) and the evolved magmas pooled at middle-crustal depths ( 0.7 GPa). Mass-balance calculations based on whole-rock and mineral compositions show that kaersutite fractionation has played a major role in magma differentiation of the sodic lineage whereas the compositional variations of the potassic lineage can be ascribed to fractionation of a kaersutite-free mineral assemblage and a maximum of 17% crustal assimilation.

Physicomechanical, In Vitro and In Vivo Performance of 3D Printed Doped Tricalcium Phosphate Scaffolds for Bone Tissue Engineering and Drug Delivery

NASA Astrophysics Data System (ADS)

Tarafder, Solaiman

Although tricalcium phosphate (TCP) is widely used in bone tissue engineering, the strength degradation kinetics is not well controlled. This study focuses on the underlying mechanism of strength degradation kinetics by incorporating trace elements in TCP. The objective of this research is to modify the mechanical properties of TCP to achieve the desired degradation rate for the specific need, and improve the in vivo bioactivity for early wound healing by incorporating trace elements such as strontium (Sr2+), magnesium (Mg2+) and silicon (Si4+) as dopants. The hypothesis of this research is that the presence of different trace elements in TCP will influence its phase stability, microstructure, mechanical strength, and both in vitro and in vivo bioactivity. Direct three dimensional printing (3DP) was used to fabricate designed interconnected macroporous pure and doped TCP scaffolds. Microwave sintering as opposed to conventional sintering was also used for better densification and higher mechanical strength. A maximum compressive strength of 10.95 +/- 1.28 MPa and 12.01 +/- 1.56 MPa were achieved for pure and Sr2+-Mg2+ doped TCP scaffolds with 500 microm designed pores (˜400 microm after sintering) sintered in microwave furnace, respectively. Substitution of Mg2+ and Sr2+ into calcium (Ca2+) sites of TCP crystal lattice contributed to phase stability and controlled gradual degradation. On the other hand, Si4+ substitution into phosphorous (P5+) sites destabilized the crystal structure and accelerated degradation of TCP. Interconnected macroporous beta-TCP scaffolds facilitated in vivo guided bone tissue regeneration through infiltration of cells and extracellular matrix into the designed pores. Presence of Sr2+, Mg2+ and Si4+ into beta-TCP induced increased in vivo early bone formation and better bone remodeling through increased extracellular matrix production such as, collagen and osteocalcin, when tested in rat and rabbit distal femur model. The presence of Si4+ along with Mg 2+ induced increased new blood vessel formation. Our results exhibited that Sr2+, Mg2+ and Si4+ doped 3DP TCP scaffolds have strong potential in bone tissue engineering applications for early wound healing.

Isotopic and trace element constraints on the petrogenesis of lavas from the Mount Adams volcanic field, Washington

USGS Publications Warehouse

Jicha, B.R.; Hart, G.L.; Johnson, C.M.; Hildreth, Wes; Beard, B.L.; Shirey, S.B.; Valley, J.W.

2009-01-01

Strontium, Nd, Pb, Hf, Os, and O isotope compositions for 30 Quaternary lava flows from the Mount Adams stratovolcano and its basaltic periphery in the Cascade arc, southern Washington, USA indicate a major component from intraplate mantle sources, a relatively small subduction component, and interaction with young mafic crust at depth. Major- and trace-element patterns for Mount Adams lavas are distinct from the rear-arc Simcoe volcanic field and other nearby volcanic centers in the Cascade arc such as Mount St. Helens. Radiogenic isotope (Sr, Nd, Pb, and Hf) compositions do not correlate with geochemical indicators of slab-fluids such as (Sr/P)n and Ba/Nb. Mass-balance modeling calculations, coupled with trace-element and isotopic data, indicate that although the mantle source for the calc-alkaline Adams basalts has been modified with a fluid derived from subducted sediment, the extent of modification is significantly less than what is documented in the southern Cascades. The isotopic and trace-element compositions of most Mount Adams lavas require the presence of enriched and depleted mantle sources, and based on volume-weighted chemical and isotopic compositions for Mount Adams lavas through time, an intraplate mantle source contributed the major magmatic mass of the system. Generation of basaltic andesites to dacites at Mount Adams occurred by assimilation and fractional crystallization in the lower crust, but wholesale crustal melting did not occur. Most lavas have Tb/Yb ratios that are significantly higher than those of MORB, which is consistent with partial melting of the mantle in the presence of residual garnet. ??18O values for olivine phenocrysts in Mount Adams lavas are within the range of typical upper mantle peridotites, precluding involvement of upper crustal sedimentary material or accreted terrane during magma ascent. The restricted Nd and Hf isotope compositions of Mount Adams lavas indicate that these isotope systems are insensitive to crustal interaction in this juvenile arc, in stark contrast to Os isotopes, which are highly sensitive to interaction with young, mafic material in the lower crust. ?? Springer-Verlag 2008.

Geology, geochronology, and geochemistry of basaltic flows of the Cat Hills, Cat Mesa, Wind Mesa, Cerro Verde, and Mesita Negra, central New Mexico

USGS Publications Warehouse

Maldonado, F.; Budahn, J.R.; Peters, L.; Unruh, D.M.

2006-01-01

The geochronology, geochemistry, and isotopic compositions of basaltic flows erupted from the Cat Hills, Cat Mesa, Wind Mesa, Cerro Verde, and Mesita Negra volcanic centres in central New Mexico indicate that each of these lavas had unique origins and that the predominant mantle involved in their production was an ocean-island basalt type. The basalts from Cat Hills (0.11 Ma) and Cat Mesa (3.0 Ma) are similar in major and trace element composition, but differences in MgO contents and Pb isotopic values are attributed to a small involvement of a lower crustal component in the genesis of the Cat Mesa rocks. The Cerro Verde rock is comparable in age (0.32 Ma) to the Cat Hills lavas, but it is more radiogenic in Sr and Nd, has higher MgO contents, and has a lower La/Yb ratio. This composition is explained by the melting of an enriched mantle source, but the involvement of another crustal component cannot be disregarded. The Wind Mesa rock is characterized by similar age (4.01 Ma) and MgO contents, but it has enriched rare-earth element contents compared with the Cat Mesa samples. These are attributed to a difference in the degree of partial melting of the Cat Mesa source. The Mesita Negra rock (8.11 Ma) has distinctive geochemical and isotopic compositions that suggest a different enriched mantle and that large amounts of a crustal component were involved in generating this magma. These data imply a temporal shift in magma source regions and crustal involvement, and have been previously proposed for Rio Grande rift lavas. ?? 2006 NRC Canada.

Effects of increased pCO2 and geographic origin on purple sea urchin (Strongylocentrotus purpuratus) calcite elemental composition

NASA Astrophysics Data System (ADS)

LaVigne, M.; Hill, T. M.; Sanford, E.; Gaylord, B.; Russell, A. D.; Lenz, E. A.; Hosfelt, J. D.; Young, M. K.

2012-12-01

Ocean acidification will likely have negative impacts on invertebrates producing skeletons composed of calcium carbonate. Skeletal solubility is partly controlled by the incorporation of "foreign" ions (such as Mg and Sr) into the crystal lattice of these skeletal structures, a process that is sensitive to a variety of biological and environmental factors. Here we explore the effects of life stage, oceanographic region of origin, and changes in the partial pressure of carbon dioxide in seawater (pCO2) on trace elemental composition in the purple sea urchin (Strongylocentrotus purpuratus). We show that, similar to other urchin taxa, adult purple sea urchins have the ability to precipitate skeleton composed of a range of biominerals spanning low to high magnesium calcites. Mg/Ca and Sr/Ca ratios were substantially lower in adult spines compared to adult tests. On the other hand, trace elemental composition was invariant among adults collected from four oceanographically distinct regions along the US west coast (Oregon, Northern California, Central California, and Southern California). Skeletons of newly settled juvenile urchins that originated from adults from the four regions exhibited intermediate Mg/Ca and Sr/Ca between adult spine and test endmembers, indicating that skeleton precipitated during early life stages is more soluble than adult spines and less soluble than adult tests. Mean skeletal Mg/Ca or Sr/Ca of juvenile skeleton did not vary with source region when larvae were reared under present-day, global-average seawater carbonate conditions (400 ppm; pH = 8.02 ± 0.03 1 SD; Ωcalcite = 3.3 ± 0.2 1 SD). However, when reared under elevated CO2 (900 ppm; pH = 7.72 ± 0.03; Ωcalcite = 1.8 ± 0.1), skeletal Sr/Ca in juveniles exhibited increased variance across the four regions. Although larvae from the northern populations (Oregon, Northern California, Central California) did not exhibit differences in Mg or Sr incorporation under elevated CO2 (Sr/Ca = 2.09 ± 0.06 mmol mol-1; Mg/Ca = 66.9 ± 4.1 mmol mol-1), juveniles of Southern California origin partitioned ∼ 8% more Sr into their skeletons when exposed to higher CO2 (Sr/Ca = 2.26 ± 0.05 vs. 2.10 ± 0.03 mmol mol-1 1 SD). Together these results suggest that the diversity of carbonate minerologies present across different skeletal structures and life stages in purple sea urchins does not translate into an equivalent plasticity of response associated with geographic variation or temporal shifts in seawater properties. Rather, composition of S. purpuratus skeleton precipitated during both early and adult life history stages appears relatively robust to spatial gradients and predicted changes in seawater carbonate chemistry for 2100. An exception to this trend may arise during early life stages, where certain populations of purple sea urchins may alter skeletal mineral precipitation rates and composition beyond a given CO2 threshold. The degree to which this latter geochemical plasticity might affect mineral stability and solubility in a future, altered ocean requires additional study.

Tracking selenium behaviour in chalk aquifer (northern France): Sr and 34S-sulphates isotopes constraints.

NASA Astrophysics Data System (ADS)

Cary, Lise; Benabderraziq, Hind; Elkhattabi, Jamal; Parmentier, Marc; Gourcy, Laurence; Négrel, Philippe

2014-05-01

Groundwaters in parts of the Paris Basin (France) are facing increasing selenium (Se) contents that can exceed the drinking water limit of 10 μg/L according to the European Framework Directive in the field of water policy (2000/60/EC). To better understand the groundwater origins and the selenium dynamics, the water chemistry of the Chalk aquifer supplying drinkable water to Lille city was studied. This area is submitted to quantitative and qualitative pressure from industrial, urban and agriculture origins. An integrated study was settled to determine the water sources and dynamics of elements, with a focus on Se. After a large chemical characterisation of the groundwater chemistry in the four field wells, a monthly monitoring was held in four wells and in the Deûle channel. Chemical analysis of major and trace elements, stable isotopes (δ18O, δ2H), strontium isotopes, and δ34S and δ18O of sulphates were realised. The chemical composition of solids sampled at various depths at vicinity of the four wells was also analysed. The specific geochemical signature of groundwater as revealed by Sr isotopes, in addition to element concentrations ratios like Mg/Sr and Se/Sr, highlighted mixture of three main groundwaters bodies: (1) the upstream groundwaters in the recharge area with the most radiogenic 87Sr/86Sr isotopic signature; (2) the confined groundwaters with high Sr concentrations due to water-rock interactions and the lowest 87Sr/86Sr isotopic signature close to the one of the chalk in Paris and London basins; (3) the Se-rich formations of Tertiary and Quaternary. The contents of Se, mainly present as SeV I (and locally as SeIV ), displayed spatial and temporal disparities that can be explained by geological and hydrogeological conditions. Se-rich clayed sediments originating from the dismantling of Se-rich tertiary formations (i.e. Ypresian) overlay the chalk formation and can be found in saturated conditions depending of the water table level. Oxidation of Se0, Se-pyrite and Se linked to organic matters happens according to two pathways. The first one is oxidation of Se species present in the reductive clayed sediments by oxidizing groundwaters during periods of high piezometric levels. The decrease of the piezometric level induces a decrease of the Se contents in groundwaters. Negative δ34S (0 to -28 ) coherent with pyrite oxidation are observed in groundwater. The second one is linked to the infiltration of nitrate-rich recharge waters through quaternary loess which also contain Se. In this case, δ34S of groundwaters are slightly positive and close to the signature of fertilizers. Denitrification by pyrite or Se0 oxidation plays a great role in enhancing Se mobility in a very reactive system. To limit the Se content in groundwaters, a precise water management is needed, e.g. mainly maintaining low piezometric levels in the chalk aquifer or avoiding mixings between contaminated wells, together with a precise knowledge of the geology of the quaternary clayed sediments.

Magnetic properties of Sr 3 NiIrO 6 and Sr 3 CoIrO 6 : Magnetic hysteresis with coercive fields of up to 55 T

DOE PAGES

Singleton, John; Kim, Jae Wook; Topping, Craig V.; ...

2016-12-08

Here, we report extraordinarily large magnetic hysteresis loops in the iridates Sr 3NiIrO 5 and Sr 3CoIrO 6. We find coercive magnetic fields of up to 55 T with switched magnetic moments ≈1μ B per formula unit in Sr 3NiIrO 6 and coercive fields of up to 52 T with switched moments ≈3μ B per formula unit in Sr 3CoIrO 6. We propose that the magnetic hysteresis involves the field-induced evolution of quasi-one-dimensional chains in a frustrated triangular configuration. In conclusion, the striking magnetic behavior is likely to be linked to the unusual spin-orbit-entangled local state of the Ir 4+more » ion and its potential for anisotropic exchange interactions.« less

A deep hydrothermal fault zone in the lower oceanic crust, Samail ophiolite Oman

NASA Astrophysics Data System (ADS)

Zihlmann, B.; Mueller, S.; Koepke, J.; Teagle, D. A. H.

2017-12-01

Hydrothermal circulation is a key process for the exchange of chemical elements between the oceans and the solid Earth and for the extraction of heat from newly accreted crust at mid-ocean ridges. However, due to a dearth of samples from intact oceanic crust, or continuous samples from ophiolites, there remain major short comings in our understanding of hydrothermal circulation in the oceanic crust, especially in the deeper parts. In particular, it is unknown whether fluid recharge and discharge occurs pervasively or if it is mainly channeled within discrete zones such as faults. Here, we present a description of a hydrothermal fault zone that crops out in Wadi Gideah in the layered gabbro section of the Samail ophiolite of Oman. Field observations reveal a one meter thick chlorite-epidote normal fault with disseminated pyrite and chalcopyrite and heavily altered gabbro clasts at its core. In both, the hanging and the footwall the gabbro is altered and abundantly veined with amphibole, epidote, prehnite and zeolite. Whole rock mass balance calculations show enrichments in Fe, Mn, Sc, V, Co, Cu, Rb, Zr, Nb, Th and U and depletions of Si, Ca, Na, Cr, Zn, Sr, Ba and Pb concentrations in the fault rock compared to fresh layered gabbros. Gabbro clasts within the fault zone as well as altered rock from the hanging wall show enrichments in Na, Sc, V, Co, Rb, Zr, Nb and depletion of Cr, Ni, Cu, Zn, Sr and Pb. Strontium isotope whole rock data of the fault rock yield 87Sr/86Sr ratios of 0.7046, which is considerably more radiogenic than fresh layered gabbro from this locality (87Sr/86Sr = 0.7030 - 0.7034), and similar to black smoker hydrothermal signatures based on epidote, measured elsewhere in the ophiolite. Altered gabbro clasts within the fault zone show similar values with 87Sr/86Sr ratios of 0.7045 - 0.7050, whereas hanging wall and foot wall display values only slightly more radiogenic than fresh layered gabbro.The secondary mineral assemblages and strontium isotope compositions of the fault rock, clasts and hanging wall indicate interaction with a seawater-derived hydrothermal fluid during oceanic spreading at an ancient mid-ocean ridge. The considerable elemental mass changes in the fault rocks and surrounds compared to the primary layered gabbros suggests extensive hydrothermal fluid flow and exchange deep within the ocean crust.

Variable sources for Cretaceous to recent HIMU and HIMU-like intraplate magmatism in New Zealand

NASA Astrophysics Data System (ADS)

van der Meer, Q. H. A.; Waight, T. E.; Scott, J. M.; Münker, C.

2017-07-01

Continental intraplate magmas with isotopic affinities similar to HIMU are identified worldwide. Involvement of an asthenospheric HIMU or HIMU-like source is contested because the characteristic radiogenic Pb compositions coupled with unradiogenic Sr and intermediate Nd and Hf compositions can also result from in-situ ingrowth in metasomatised lithospheric mantle. Sr-Nd-Pb-Hf isotopic compositions of late Cretaceous lamprophyre dikes from Westland, New Zealand, provide new insights into the formation of a HIMU-like alkaline intraplate magmatic province under the Zealandia continent. The oldest (102-100 Ma) calc-alkaline lamprophyres are compositionally similar to the preceding arc-magmatism (206Pb/204Pb(i) = 18.6, 207Pb/204Pb(i) = 15.62, 208Pb/204Pb(i) = 38.6, 87Sr/86Sr(i) = 0.7063-0.7074, εNd(i) = -2.1 - +0.1 and εHf(i) = -0.2 - +2.3) and are interpreted as melts originating from subduction-modified lithosphere. Alkaline dikes erupted on the inboard Gondwana margin shortly after cessation of subduction (92-84 Ma) have heterogeneous isotopic properties: 206Pb/204Pb(i) = 18.7 to 19.4, 207Pb/204Pb(i) = 15.60 to 15.65, 208Pb/204Pb(i) = 38.6 to 39.4, 87Sr/86Sr(i) = 0.7031 to 0.7068, εNd(i) = +4.5 to +8.0 and εHf(i) = +5.1 to +8.0. Melt compositions point to an amphibole-bearing spinel facies lithospheric mantle source enriched by metasomatism that introduced, amongst many elements, U + Th which lead to rapid ingrowth to HIMU-like compositions. Importantly, this HIMU-like source enrichment appears to have completely originated from the complex local subduction history. A coeval episode of alkaline magmatism (mainly 98-82 Ma) occurred outboard of Gondwana's former active margin and on the Hikurangi oceanic plateau (accreted to Zealandia in the Early Cretaceous) with compositions closer to true HIMU (206Pb/204Pb(i) ≈ 20.5, 207Pb/204Pb(i) ≈ 15.7, 208Pb/204Pb(i) ≈ 40.0, εNd(i) ≈ 4.5 and εHf(i) ≈ 4.0). In contrast to the inboard HIMU-like magmas, the radiogenic 207Pb/204Pb and relatively unradiogenic Nd and Hf require an ancient enriched source component. This magmatism is interpreted to represent melting of a fossilised HIMU source that resided under the Hikurangi Plateau. These genetically distinct but isotopically similar intraplate reservoirs were separated by the down-going slab under Gondwana's former active margin. Ancient HIMU magmatism was locally replaced by the young HIMU-like type which became dominant across Zealandia during the Late Cretaceous. Our research suggests that the sources for alkaline intraplate magmas with compositions similar to ocean island basalts can be formed either with or without the involvement of a plume-derived component.

Aerodynamic Optimization of a Supersonic Bending Body Projectile by a Vector-Evaluated Genetic Algorithm

DTIC Science & Technology

2016-12-01

Evaluated Genetic Algorithm prepared by Justin L Paul Academy of Applied Science 24 Warren Street Concord, NH 03301 under contract W911SR...Supersonic Bending Body Projectile by a Vector-Evaluated Genetic Algorithm prepared by Justin L Paul Academy of Applied Science 24 Warren Street... Genetic Algorithm 5a. CONTRACT NUMBER W199SR-15-2-001 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Justin L Paul 5d. PROJECT

Pb-, Sr- and Nd-Isotopic systematics and chemical characteristics of cenozoic basalts, Eastern China

USGS Publications Warehouse

Peng, Z.C.; Zartman, R.E.; Futa, K.; Chen, D.G.

1986-01-01

Forty-eight Paleogene, Neogene and Quaternary basaltic rocks from northeastern and east-central China have been analyzed for major-element composition, selected trace-element contents, and Pb, Sr and Nd isotopic systematics. The study area lies entirely within the marginal Pacific tectonic domain. Proceeding east to west from the continental margin to the interior, the basalts reveal an isotopic transition in mantle source material and/or degree of crustal interaction. In the east, many of the rocks are found to merge both chemically and isotopically with those previously reported from the Japanese and Taiwan island-arc terrains. In the west, clear evidence exists for component(s) of Late Archean continental lithosphere to be present in some samples. A major crustal structure, the Tan-Lu fault, marks the approximate boundary between continental margin and interior isotopic behaviors. Although the isotopic signature of the western basalts has characteristics of lower-crustal contamination, a subcrustal lithosphere, i.e. an attached mantle keel, is probably more likely to be the major contributor of their continental "flavor". The transition from continental margin to interior is very pronounced for Pb isotopes, although Sr and Nd isotopes also combine to yield correlated patterns that deviate strikingly from the mid-ocean ridge basalt (MORB) and oceanic-island trends. The most distinctive chemical attribute of this continental lithosphere component is its diminished U Pb as reflected in the Pb isotopic composition when compared to sources of MORB, oceanic-island and island-arc volcanic rocks. Somewhat diminished Sm Nd and elevated Rb Sr, especially in comparison to the depleted asthenospheric mantle, are also apparent from the Nd- and Sr-isotopic ratios. ?? 1986.

Rb-Sr systematics and REE abundances in Shalka and several other diogenites

NASA Astrophysics Data System (ADS)

Takahashi, K.; Yabuki, S.; Kagi, H.; Masuda, A.

1994-07-01

The diogenites have been regarded as igneous products in the early solar system and they have been considered to have genetically close relationship with eucrites. Depsite their simple mineralogical compositions and narrow range for major-element compositions, diogenites have been known to show wide Rare Earth Elements (REE) variations in absolute concentration and in mutual abundance ratios. Furthermore, some diogenites have peculiar Rb-Sr isotope systematics (ages younger than 4.5 b.y.). The Shalka meteorite belongs to the diogenites, and a unique REE abundance pattern has been reported. We performed Rb-Sr isotopic analyses and measured REE abundances in the Shalka diogenite with several other diogenites to discuss their genesis. Roughly speaking, REE patterns in diogenites are characterized by the negative Eu anomaly and the depletion of light REE. For Shalka, some heterogeneity in REE abundance patterns have been observed. While one sample chip shows the REE pattern with a large negative Eu anomaly and depleted light REE, particularly characterized by the concave curvature for the La-Nd span, other samples show the pattern nearly flat or the pattern enriched in light REE. These variations could not be explained easily by the simple mixing process of LREE-depleted components and LREE-enriched melt, but they imply some metamorphism process. The Rb-Sr isotopic data for Shalka are shown with the data for other several diogenites. These observations indicate that Shalka would undergo a significant extent of metamorphism followed by redistribution of REE and the disturbance of the Rb-Sr systematics. We are going to do further studies on Shalka to discuss the metamorphic process and compare it with other diogenites.

Increase in accumulation of strontium-90 in the maternal skeleton during pregnancy and lactation: analysis of the Techa River data.

PubMed

Tolstykh, Evgenia I; Shagina, Natalia B; Degteva, Marina O

2014-08-01

The unique contamination of the Techa River (Southern Urals, Russia) in the 1950s by long-lived (90)Sr allows investigation of the accumulation of bone-seeking elements in humans. This study is based on information compiled at the Urals Research Center for Radiation Medicine (Chelyabinsk, Russia) over a long period of time. It includes the results of in vivo measurements of (90)Sr-body burden with a whole body counter (WBC), data on personal medical examinations and residence and family histories. Data on 185 women from two Techa riverside villages Muslyumovo and Brodokalmak were selected. The settlements differ in terms of (90)Sr diet intake (higher in Muslyumovo than in Brodokalmak) and ethnicity (residents were mainly Slavs in Brodokalmak and Turkic in Muslyumovo). Results of a total of 555 WBC measurements performed in 1974-1997 were available for the women studied; maximum measured values reached 40 kBq/body. The women from each settlement were subdivided into three groups according to their childbearing history: pregnancy and lactation occurred (1) during the period of maximal (90)Sr intake (1950-1951); (2) after the period of maximal intake and (3) before this period or women who were childless. An increase was found in accumulation of (90)Sr in maternal skeleton during pregnancy and lactation (group 1) by a factor of 1.5-2 in comparison with non-pregnant, non-lactating women. This result was found in both Muslyumovo and Brodokalmak samples. An increase in accumulation of toxic elements in pregnant/lactating women is associated with increased radiation/toxic doses and risk for the women's health.

Carbonatite and silicate melt metasomatism of the mantle surrounding the Hawaiian plume: Evidence from volatiles, trace elements, and radiogenic isotopes in rejuvenated-stage lavas from Niihau, Hawaii

NASA Astrophysics Data System (ADS)

Dixon, Jacqueline; Clague, David A.; Cousens, Brian; Monsalve, Maria Luisa; Uhl, Jessika

2008-09-01

We present new volatile, trace element, and radiogenic isotopic compositions for rejuvenated-stage lavas erupted on Niihau and its submarine northwest flank. Niihau rejuvenated-stage Kiekie Basalt lavas are mildly alkalic and are isotopically similar to, though shifted to higher 87Sr/86Sr and lower 206Pb/204Pb than, rejuvenated-stage lavas erupted on other islands and marginal seafloor settings. Kiekie lavas display trace element heterogeneity greater than that of other rejuvenated-stage lavas, with enrichments in Ba, Sr, and light-rare earth elements resulting in high and highly variable Ba/Th and Sr/Ce. The high Ba/Th lavas are among the least silica-undersaturated of the rejuvenated-stage suite, implying that the greatest enrichments are associated with the largest extents of melting. Kiekie lavas also have high and variable H2O/Ce and Cl/La, up to 620 and 39, respectively. We model the trace element concentrations of most rejuvenated-stage lavas by small degrees (˜1% to 9%) of melting of depleted peridotite recently metasomatized by a few percent of an enriched incipient melt (0.5% melting) of the Hawaiian plume. Kiekie lavas are best explained by 4% to 13% partial melting of a peridotite source metasomatized by up to 0.2% carbonatite, similar in composition to oceanic carbonatites from the Canary and Cape Verde Islands, with lower proportion of incipient melt than that for other rejuvenated-stage lavas. Primary H2O and Cl of the carbonatite component must be high, but variability in the volatile data may be caused by heterogeneity in the carbonatite composition and/or interaction with seawater. Our model is consistent with predictions based on carbonated eclogite and peridotite melting experiments in which (1) carbonated eclogite and peridotite within the Hawaiian plume are the first to melt during plume ascent; (2) carbonatite melt metasomatizes plume and surrounding depleted peridotite; (3) as the plume rises, silica-undersaturated silicate melts are also produced and contribute to the metasomatic signature. The metasomatic component is best preserved at the margins of the plume, where low extents of melting of the metasomatized depleted mantle surrounding the plume are sampled during flexural uplift. Formation of carbonatite melts may provide a mechanism to transfer plume He to the margins of the plume.

Flame photometric determination of strontium in water

USGS Publications Warehouse

Skougstad, Marvin W.

1957-01-01

Preliminary search of reported methods of Sr analysis revealed several investigations which have been made for the determination of Sr with the flame photometer, both at relatively low concentrations (0 to 50 ppm Sr) and at higher concentrations. Generally the procedures described involved measurement of Sr emission at either 460.7 mu or at 681 mu. There is disagreement among those reporting methods for Sr as to the preference of the one wavelength over the other. The 681 line (or band) seems to be preferred because of its greater reproducibility and relative freedom from interference. The 460.7 mu line, however, lies in the region of greater sensitivity of the photomultiplier tube, and hence for this reason is preferred by some. This is an advantage, of course, when determining Sr at very low concentrations. This investigation is concerned with determining the optimum conditions for the determination of Sr at low concentration levels in water samples. Early experimental work indicated a greater sensitivity for the 460.7 mu (hereafter designated as 461 mu) Sr line. Therefore, most of the subsequent work was based on a study of the effects of various other materials and conditions on the emission of Sr at this wavelength.

Ca, Sr and Ba stable isotopes reveal the fate of soil nutrients along a tropical climosequence

USGS Publications Warehouse

Bullen, Thomas D.; Chadwick, Oliver A.

2016-01-01

Nutrient biolifting is an important pedogenic process in which plant roots obtain inorganic nutrients such as phosphorus (P) and calcium (Ca) from minerals at depth and concentrate those nutrients at the surface. Here we use soil chemistry and stable isotopes of the alkaline earth elements Ca, strontium (Sr) and barium (Ba) to test the hypothesis that biolifting of P has been an important pedogenic process across a soil climosequence developed on volcanic deposits at Kohala Mountain, Hawaii. The geochemical linkage between these elements is revealed as generally positive site-specific relationships in soil mass gains and losses, particularly for P, Ba and Ca, using the ratio of immobile elements titanium and niobium (Ti/Nb) to link individual soil samples to a restricted compositional range of the chemically and isotopically diverse volcanic parent materials. At sites where P is enriched in surface soils relative to abundances in deeper soils, the isotope compositions of exchangeable Ca, Sr and Ba in the shallowest soil horizons (< 10 cm depth) are lighter than those of the volcanic parent materials and trend toward those of plants growing on fresh volcanic deposits. In contrast the isotope composition of exchangeable Ba in deeper soil horizons (> 10 cm depth) at those sites is consistently heavier than the volcanic parent materials. The isotope compositions of exchangeable Ca and Sr trend toward heavier compositions with depth more gradually, reflecting increasing leakiness from these soils in the order Ba < Sr < Ca and downward transfer of light biocycled Ca and Sr to deeper exchange sites. Given the long-term stability of ecosystem properties at the sites where P is enriched in surface soils, a simple box model demonstrates that persistence of isotopically light exchangeable Ca, Sr and Ba in the shallowest soil horizons requires that the uptake flux to plants from those near-surface layers is less than the recycling flux returned to the surface as litterfall. This observation implicates an uptake flux from an additional source which we attribute to biolifting. We view the heavy exchangeable Ba relative to soil parent values in deeper soils at sites where P is enriched in surface soils, and indeed at all but the wettest site across the climosequence, to represent the complement of an isotopically light Ba fraction removed from these soils by plant roots consistent with the biolifting hypothesis. We further suggest that decreasing heaviness of depth-integrated exchangeable Ba in deeper soils with increasing median annual precipitation across the climosequence reflects greater reliance on shallow nutrient sources as site water balance increases. While the Ca, Sr and Ba isotopes considered together were useful in confirming an important role for nutrient biolifting across the climosequence, the Ba isotopes provided the most robust tracer of biolifting and have the greatest potential to find application as an isotopic proxy for P dynamics in soils.

Autigenic and Anthropogenic Uranium in the Marine Sediments of the Gulf of California in Front of Santa Rosalia Mining District

NASA Astrophysics Data System (ADS)

Choumiline, K.; Rodríguez-Figueroa, G.; Shumilin, E.; Sapozhnikov, D.

2007-05-01

To verify the possibilities of U enrichments in the marine sedimentary environment of the eastern sector of the central Gulf of Califoria (GC), eleven sediment cores were collected in front of the Santa Rosalia mining region, peninsula of Baja California. Uranium and some other trace element contents in sliced core layers, dried and homogenized, were determined using instrumental neutron activation analysis. Average total U contents in sediments of five cores collected in the open GC in front of Santa Rosalía at sites with water depths from 265 m to 1030 m and in the Guaymas Basin with 2019 m, ranged from 1.36±0.26 mg kg-1 (Guaymas Basin) to 9.31±3.03 mg kg-1 (SR63 core, depth 630 m). To distinguish non-lithogenic U from the lithogenic one, the normalization of total U contents to the concentrations of Sc in the samples was used. That because this element is a reliable indicator of crustal materials, mainly aluminosilicates in the marine sediments. The relative contribution of non-lithogenic (authigenic) U varied from 49.8±3 % (Guaymas Basin) to 84.2±8.2 % (SR62 core) of the total U content in the sediments of the open central GC. Surprisingly, in three sediment cores from the coastal zone adjacent to the town of Santa Rosalía in water depth range 3-6 m very high concentrations of total U were found, ranging from 54.2±7.3 mg kg-1 (SR4 core) to 110±13 mg kg-1 (SR2 core) and exceeding not only U average abundance in the earth´s crust (2.7 mg kg-1), but also its levels found for SR62 core, as well as those reported for natural enrichments of U in suboxic-anoxic environments, e.g. at Mexico and Peru margin sites (3.04 mg kg-1 - 24.54 mg kg-1, McManus et al., 2006). The relative contribution of non-lithogenic U in the sediments of these three anomalous cores varied from 97.2±0.4 % (SR4 core) to 98.80.2 % (SR1 and SR2 cores) of their total U content. The sediments were also depleted in organic C (0.05 % - 0.18 %), which is not typical for marine solid phases enriched in authigenic U. Additional surface sampling around the cores with high levels of U, helped to define the spatial distribution of this element, as well as Co, Cu, Zn, light lanthanides and europium, which also showed "anomalies". The association with anthropogenic impact is discussed because the geochemical fingerprints of these sediments are the same as for solid wastes of copper smelting, which has occurred in Santa Rosalía in the past century till 1984.

Super heavy element Copernicium: Cohesive and electronic properties revisited

NASA Astrophysics Data System (ADS)

Gyanchandani, Jyoti; Mishra, Vinayak; Dey, G. K.; Sikka, S. K.

2018-01-01

First principles scalar relativistic (SR) calculations with and without including the spin orbit (SO) interactions have been performed for solid Copernicium (Cn) to determine its ground state equilibrium structure, volume, bulk modulus, pressure derivative of the bulk modulus, density of states and band structure. Both SR and SR+SO calculations have been performed with 6p levels treated as part of core electrons and also as part of valence electrons. These calculations have been performed for the rhombohedral, BCT, FCC, HCP, BCC and SC structures. Results have been compared with the results for Hg which is lighter homologue of Cn in the periodic table. We find hcp to be the stable crystal structure at SR level of theory and also at SR+SO level of theory when the 6p electrons are treated as part of core electrons. With 6p as part of valence electrons, SR+SO level of computations, however, yield bcc structure to be the most stable structure. Equilibrium volume (V0) of the most stable crystal structure at SR level of theory viz. hcp structure is 188.66 a.u.3whereas its value for the bcc structure, the equilibrium ground state structure at SR+SO level of theory is 165.71 a.u.3 i.e a large change due to relativistic effects is seen. The density of states at Fermi level is much smaller in Cn than in Hg, making it a poorer metal than mercury. In addition the cohesive energy of Cn is computed to be almost two times that of Hg for SR+SO case.