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Sample records for platinum-group element accumulation

  1. Accumulation of platinum group elements by the marine gastropod Littorina littorea.

    PubMed

    Mulholland, Rachel; Turner, Andrew

    2011-04-01

    The accumulation and trophic transfer of the platinum group elements (PGE): Rh, Pd and Pt; have been studied in short-term (5 day) exposures conducted in aquaria containing the marine macroalga, Ulva lactuca, and/or the grazing mollusc, Littorina littorea. Metals added to sea water (to concentrations of 20 μg L⁻¹) were taken up by U. lactuca in the order Rh, Pt > Pd and by L. littorea in the order Pd ≥ Pt ≥ Rh, with greatest metal accumulation in the latter generally occurring in the visceral complex and kidney. When fed contaminated alga, accumulation of Rh and Pd by L. littorea, relative to total available metal, increased by an order of magnitude, while accumulation of Pt was not readily detected. We conclude that the diet is the most important vector for accumulation of Rh and Pd, while accumulation of Pt appears to proceed mainly from the aqueous phase. PMID:21237543

  2. Extra- and intra-cellular accumulation of platinum group elements by the marine microalga, Chlorella stigmatophora.

    PubMed

    Shams, Leyla; Turner, Andrew; Millward, Geoffrey E; Brown, Murray T

    2014-03-01

    To better understand the marine biogeochemistry of the platinum group elements (PGE), Rh(III), Pd(II) and Pt(IV) were added in combination and at ppb concentrations to cultures of the marine microalga, Chlorella stigmatophora, maintained in sea water at 15 °C and under 60 μmol m(-2) s(-1) PAR. The accumulation of PGE was established in short-term (24-h) exposures, and under varying conditions of algal biomass and PGE concentration, and in a longer-term exposure (156-h) by ICP-MS analysis of sea water and nitric acid digests and EDTA washes of the alga. In short-term exposures, and under all conditions, the extent of accumulation by C. stigmatophora was in the order: Rh > Pd > Pt; and Pd was internalised (or resistant to EDTA extraction) to a considerably greater extent than Rh and Pt. Accumulation isotherms were quasi-linear up to added PGE concentrations of 30 μg L(-1) and all metals displayed a significant reduction in accumulation on a weight-normalised basis with increasing density (biomass) of C. stigmatophora, an effect attributed to the production of exudates able to stabilise metals in sea water through complexation. In the longer-term exposure, kinetic constraints on the reactivities of Rh and, in particular, Pt, resulted in final degrees of accumulation and internalisation by C. stigmatophora that were greatest for Rh and similar between Pd and Pt. Among the PGE, therefore, Rh is predicted to participate in biological removal and transport processes in the marine environment to the greatest extent while decoupling in the biogeochemistries of Pd and Pt is predicted in shorter-term or more transient processes. PMID:24268058

  3. Accumulation and distribution characteristics of platinum group elements in roadside dusts in Beijing, China.

    PubMed

    Gao, Bo; Yu, Yanke; Zhou, Huaidong; Lu, Jin

    2012-06-01

    The concentrations, distribution, and accumulation of platinum group elements (PGEs) were investigated in roadside dusts collected in four different foundational areas in Beijing during February to May 2010. The results showed that PGE levels in all samples were above the average upper crust values, with mean concentrations of 57.5 ng · g(-1) Pd, 28.2 ng · g(-1) Pt, and 9.8 ng · g(-1) Rh, respectively. Palladium concentration has increased rapidly in recent years. The rank of PGE levels in four different functional regions for roadside dusts was: heavy density traffic area > residential area > educational area > tourism area. Palladium, Pt, and Rh concentrations in dusts showed strong positive correlations, indicating a common traffic-related source of these metals. Meanwhile, PGEs in these samples were not correlated with other traffic-related metals except for Cr. The average PGE ratios of road dusts from Beijing were consistent with those in Germany and Western Australia, but lower than those in the United States and Mexico, indicating that various catalyst productions were used in different countries. In addition, grain-size partitioning of PGEs in dusts indicated that concentrations of PGEs differed from one particle size to another. The coarse fraction had higher PGE concentrations than the fine fraction in roadside dusts. These results showed that autocatalyst PGE contamination estimates in the environment would be significantly underestimated if only a fine-grain size fraction (<0.063 mm) is analyzed. PMID:22505271

  4. Implications of platinum-group element accumulation along U.S. roads from catalytic-converter attrition.

    PubMed

    Ely, J C; Neal, C R; Kulpa, C F; Schneegurt, M A; Seidler, J A; Jain, J C

    2001-10-01

    Automobile catalytic converters are dispersing platinum-group elements (PGEs) Rh, Pt, and Pd into the environment (1-3). This paper represents the first detailed study to assess the PGE content of soils and grasses from U.S. roadsides. These soils were analyzed using cation exchange pretreatment and ultrasonic nebulizer-ICP-MS (4). Highway and several urban sites showed Pt abundances of 64-73 ng/g immediately adjacent to the roadside, with corresponding Pd and Rh abundances of 18-31 ng/g and 3-7 ng/g, respectively. All Pt and most Pd and Rh abundances are statistically above local background soil values. Platinum, Rd, and Rh show positive correlations with traffic-related elements (Ni, Cu, Zn, and Pb) but no correlations with nontraffic-related elements (Y, Ga). Iridium and Ru show no correlations with any of these trace elements. These PGE abundances are comparable to European studies (5-7) and are approaching concentrations that would be economically viable to recover. This study also demonstrates transport of Pt statistically above background more than 50 m from the roadside. Further study is necessary to see how mobile the PGEs are in roadside environments, but these initial data indicate only Pt is taken up by plants. PMID:11642438

  5. Quantitative bioimaging of platinum group elements in tumor spheroids.

    PubMed

    Niehoff, Ann-Christin; Grünebaum, Jonas; Moosmann, Aline; Mulac, Dennis; Söbbing, Judith; Niehaus, Rebecca; Buchholz, Rebecca; Kröger, Sabrina; Wiehe, Arno; Wagner, Sylvia; Sperling, Michael; von Briesen, Hagen; Langer, Klaus; Karst, Uwe

    2016-09-28

    Limited drug penetration into tumor tissue is a significant factor to the effectiveness of cancer therapy. Tumor spheroids, a 3D cell culture model system, can be used to study drug penetration for pharmaceutical development. In this study, a method for quantitative bioimaging of platinum group elements by laser ablation (LA) coupled to inductively coupled plasma mass spectrometry (ICP-MS) is presented. Different matrix-matched standards were used to develop a quantitative LA-ICP-MS method with high spatial resolution. To investigate drug penetration, tumor spheroids were incubated with platinum complexes (Pt(II)acetylacetonate, cisplatin) and the palladium tagged photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP). Distribution and accumulation of the pharmaceuticals were determined with the developed method. PMID:27619092

  6. Platinum group elements in the environment and their health risk.

    PubMed

    Ravindra, Khaiwal; Bencs, László; Van Grieken, René

    2004-01-01

    Accumulation of platinum group elements (PGEs) in the environment has been increased over the time. Catalytic converters of modern vehicles are considered to be the main sources of PGE pollution, since the correlation is between the Pt:Rh ratios in various environmental compartments and in converter units. The present literature survey shows that the concentration of these metals has increased significantly in the last decades in diverse environmental matrices; like airborne particulate matter, soil, roadside dust and vegetation, river, coastal and oceanic environment. Generally, PGEs are referred to behave in an inert manner and to be immobile. However, there is an evidence of spread and bioaccumulation of these elements in the environment. Platinum content of road dusts can be soluble, consequently, it enters the waters, sediments, soil and finally, the food chain. The effect of chronic occupational exposure to Pt compounds is well-documented, and certain Pt species are known to exhibit allergenic potential. However, the toxicity of biologically available anthropogenic Pt is not clear. Hence, there is a need to study the effect on human health of long-term chronic exposure to low levels of Pt compounds. PMID:14654273

  7. Photochemistry and charge transfer chemistry of the platinum group elements

    SciTech Connect

    Eisenberg, R.

    1991-12-01

    Significant progress has been made on the photochemistry and photophysics of platinum group element dithiolate complexes. The specific systems under investigation are square planar complexes of Pt(II) containing a dithiolate chelate and two other donor groups to complete the coordination sphere. The donor groups may be amines, imines, phosphines, phosphites or olefins, and they can be either monodentate or joined together as part of a chelate ring.

  8. Roadside Accumulation of Pt, Pd, Rh and Other Trace Elements From Automobiles: Catalytic Converter Attrition and Platinum-Group Element Mobility in the Roadside Environment.

    NASA Astrophysics Data System (ADS)

    Ely, J. C.; Dahlheimer, S. R.; Neal, C. R.

    2003-12-01

    Elemental abundances of Pt, Pd and Rh have been documented across the industrialized world in roadside environments due to attrition of automotive catalytic converters (Zereini and Alt, 2000, Anthropogenic PGE Emissions, Springer, 308pp; Ely et al., 2001, EnvSci&Tech, 35:3816-3822; Whiteley and Murray, 2003, SciTotEnv, in press). In our ongoing study, the highest reported roadside Pt abundance 1.8 ppm has been found immediately adjacent to the road at a field site in South Bend, IN, USA. Furthermore, initial studies show positive correlations of Pt, Pd and Rh with some trace elements (Ni, Cu, Zn and Pb), which has been confirmed by further analysis for these and other elements (Ce, Cr). It has been demonstrated that elements such as Ce are present in catalytic converters at concentrations of 100's ppm to 3-wt.%. These elements are also being attrited with Pt, Pd and Rh and aerially transported and deposited. Our field site was established next to US-933 adjacent to the Notre Dame campus. Areas were cleared of the top 2-4 cm of soil (removing surficial Pt, Pd and Rh) at 1, 5, 10 and 50 meters from the roadside. Within 3 months the 1-meter site contained 67% of the initial Rh and Pt concentrations and 100% of the initial Pd concentration. The sites at 5, 10 and 50 meters showed similar results, in some cases exceeding the initial concentrations. After 6 months the concentrations of Pt, Pd and Rh were all within error of the initial concentrations, indicating steady state abundances had probably been reached. Grass samples from each site showed that washed vs. unwashed samples were within error of each other, and there may be a slight enrichment (approx. 1 ppb) in the grasses of Pd and Pt, but this enrichment was independent of distance from the road. The steady-state situation suggests that the PGEs are being removed from the immediate roadside environment, which requires that the metals are being oxidized and/or complexed in such a way to facilitate transport. The

  9. Platinum-group element abundance patterns in different mantle environments

    SciTech Connect

    Rehkaemper, M.; Halliday, A.N.; Barfod, D.; Fitton, J.G.; Dawson, J.B.

    1997-11-28

    Mantle-derived xenoliths from the Cameroon Line and northern Tanzania display differences in their platinum-group element (PGE) abundance patterns. The Cameroon Line lherzolites have uniform PGE patterns indicating a homogeneous upper mantle over several hundreds of kilometers, with approximately chondritic PGE ratios. The PGE patterns of the Tanzanian peridotites are similar to the PGE systematics of ultramafic rocks from ophiolites. The differences can be explained if the northern Tanzanian lithosphere developed in a fluid-rich suprasubduction zone environment, whereas the Cameroon Line lithosphere only experienced melt extraction from anhydrous periodotites. 32 refs., 2 figs., 1 tab.

  10. Platinum-group element resources in podiform chromitites from California and Oregon.

    USGS Publications Warehouse

    Page, N.J.; Singer, D.A.; Moring, B.C.; Carlson, C.A.; McDade, J.M.; Wilson, S.A.

    1986-01-01

    Assays of Pt, Pd, Rh and Ir from approx 280 podiform chromite deposits in Palaeozoic and Mesozoic ophiolites are statistically analysed to estimate their possible by-product value from mining the chromite. The platinum-group elements occur in discrete platinum-group minerals, and in solid solution in Cu-Ni-Fe sulphides. Low grades and small amounts of total platinum-group elements in podiform chromite deposits imply a small resource. -G.J.N.

  11. Platinum-group elements: so many excellent properties

    USGS Publications Warehouse

    Zientek, Michael L.; Loferski, Patricia J.

    2014-01-01

    The platinum-group elements (PGE) include platinum, palladium, rhodium, ruthenium, iridium, and osmium. These metals have similar physical and chemical properties and occur together in nature. The properties of PGE, such as high melting points, corrosion resistance, and catalytic qualities, make them indispensable to many industrial applications. PGE are strategic and critical materials for many nations because they are essential for important industrial applications but are mined in a limited number of places and have no adequate substitutes. Exploration and mining companies have found approximately 104,000 metric tons of PGE (with minor gold) in mineral deposits around the world that could be developed. For PGE, almost all known production and resources are associated with three geologic features: the Bushveld Complex, a layered mafic-to-ultramafic intrusion in South Africa; the Great Dyke, a layered mafic-to-ultramafic intrusion in Zimbabwe; and sill-like intrusions associated with flood basalts in the Noril’sk-Talnakh area, Russia. To help predict where PGE supplies might be located, USGS scientists study how and where PGE resources are concentrated in the Earth's crust and use that knowledge to assess the likelihood that undiscovered PGE deposits may exist. Techniques used for assessing mineral resources were developed by the USGS to support the stewardship of Federal lands and evaluate mineral resource availability in a global context. The USGS also compiles statistics and information on the worldwide supply, demand, and flow of PGE. These data are all used to inform U.S. national policymakers.

  12. Bioaccessibility of platinum group elements in automotive catalytic converter particulates.

    PubMed

    Turner, Andrew; Price, Simon

    2008-12-15

    The bioaccessibilities of the platinum group elements (PGE): Rh, Pd, and Pt; and the catalyzator poison, Pb, have been determined in particles derived from milled automotive catalytic converters using a physiologically based extraction test (PBET) that simulates, sequentially, the chemical conditions encountered in the human stomach and intestine. PGE accessibility, relative to total metal concentration, was generally less than a few percent, but increased in the stomach with decreasing pH (from 4 to 1) and/or increasing chloride concentration, and with decreasing particle concentration. In most cases, bioaccessibility increased from the acidic stomach to the neutral, carbonate-rich intestine. Bioaccessibility of Pb displayed similar pH and particle concentration dependencies to PGE in the stomach, but this metal exhibited significantly greater mobilization (up to 80%) overall and a reduction in accessibility from the stomach to intestine. Reaction kinetics of PGE dissolution in the stomach at pH 2.5 were modeled using a combined surface reaction-diffusion controlled mechanism with rate constants of 0.068, 0.031, and 0.015 (microg L(-1))(-1) h(-1) for Rh, Pd, and Pt, respectively. For Pb, however, mobilization proceeded via a different mechanism whose time-dependence was fitted with an empirical, logarithmic equation. Overall, PGE bioaccessibility appeared to be controlled by dissolution rates of metallic nanoparticles in the stomach, and solubility and kinetic constraints on inorganic species (chlorides, hydroxychlorides, and carbanatochlorides) and undefined organic complexes formed in the simulated gastrointestinal tract. Further studies are required to elucidate any effects engendered by the long-term oral exposure of small quantities of these species. PMID:19174929

  13. Platinum group elements in mantle melts and mantle samples

    NASA Astrophysics Data System (ADS)

    Barnes, Stephen J.; Mungall, James E.; Maier, Wolfgang D.

    2015-09-01

    A large data compilation has been assembled of platinum group element (PGE) analyses in mantle melts and mantle rocks, the latter including an assortment of xenoliths and obducted mantle massifs. The degree of correlation has been investigated among the PGEs and with other major element variables such as Al2O3, TiO2 and Mg number, and the results are considered in the context of the current paradigm for the behaviour of highly siderophile elements in the silicate Earth. Primitive mantle melts have a wide range of PGE contents. Komatiites have the highest abundances of all the PGEs, show the strongest correlations between Pt and Rh, Pt and Pd and between the iridium-group PGEs Ir, Ru and Os (IPGEs). Most basalts of all affinities have lower levels of Pt and Pd and much lower levels of Ir, Ru and Os than komatiites. Within the basalt grouping Rh has stronger affinities with the IPGEs. Picrites and Archaean basalts are intermediate between these two groups. MORBs and a small proportion of continental LIP basalts show strong depletions in all PGEs attributable to retention of sulfide in their mantle source rocks, or sulfide liquid fractionation on ascent. The degree of PGE depletion in other basalts is probably attributable to equilibration with sulfide, but is less than would be expected under conventional models of sulfide extraction, and is instead attributed to mixing of magmas generated at variable depths incorporating both sulfide-saturated and undersaturated components. Basalts with Pt and Pd contents higher than typical komatiites are rare, a notable example being B1-type parent magmas to the Bushveld Complex, which have komatiite-like relative PGE abundances and Pt, Pd and Rh abundances up to a factor of two higher than komatiites for comparable Ti contents. The mantle composition array as a whole is characterized by variable degrees of depletion of Pt, Pd and Rh in Al-poor, melt-depleted harzburgite/dunite lithologies; lack of depletion in these elements in

  14. Concentrations of platinum group elements in 122 U.S. coal samples

    USGS Publications Warehouse

    Oman, C.L.; Finkelman, R.B.; Tewalt, S.J.

    1997-01-01

    Analysis of more than 13,000 coal samples by semi-quantitative optical emission spectroscopy (OES) indicates that concentrations of the platinum group elements (iridium, palladium, platinum, osmium, rhodium, and ruthenium) are less than 1 ppm in the ash, the limit of detection for this method of analysis. In order to accurately determine the concentration of the platinum group elements (PGE) in coal, additional data were obtained by inductively coupled plasma mass spectroscopy, an analytical method having part-per-billion (ppb) detection limits for these elements. These data indicate that the PGE in coal occur in concentrations on the order of 1 ppb or less.

  15. New data on platinum group elements in sulfide deposits of the Southern Urals

    NASA Astrophysics Data System (ADS)

    Kovalev, S. G.; Puchkov, V. N.; Salikhov, D. N.

    2015-09-01

    New data on the concentrations of gold and platinum group elements (PGE) in sulfide deposits of the Southern Urals show that a substantial share of Au, Pt, and Pd is concentrated during technological ore processing in their dressing tailings. The behavior of Pt, Pd, and, partly, Au is determined by the size of individual mineral particles.

  16. Environmental routes for platinum group elements to biological materials--a review.

    PubMed

    Ek, Kristine H; Morrison, Gregory M; Rauch, Sebastien

    2004-12-01

    The increased use of platinum group elements (PGE) in automobile catalysts has led to concern over potential environmental and biological accumulation. Platinum (Pt), palladium (Pd) and rhodium (Rh) concentrations have increased in the environment since the introduction of automobile catalysts. This review summarises current knowledge concerning the environmental mobility, speciation and bioavailability of Pt, Pd and Rh. The greater proportion of PGE emissions is from automobile catalysts, in the form of nanometer-sized catalyst particles, which deposit on roadside surfaces, as evidenced in samples of road dust, grass and soil. In soil, PGE can be transformed into more mobile species through complexation with organic matter and can be solubilised in low pH rainwater. There are indications that environmentally formed Pd species are more soluble and hence more mobile in the environment than Rh and Pt. PGE can reach waterbodies through stormwater transport and deposition in sediments. Besides external contamination of grass close to roads, internal PGE uptake has been observed for plants growing on soil contaminated with automobile catalyst PGE. Fine particles of PGE were also detected on the surface of feathers sampled from passerines and raptors in their natural habitat, and internal organs of these birds also contained PGE. Uptake has been observed in sediment-dwelling invertebrates, and laboratory studies have shown an uptake of PGE in eel and fish exposed to water containing road dust. The available evidence indicates that the PGE, especially Pd, are transported to biological materials through deposition in roots by binding to sulphur-rich low molecular weight species in plants. PGE uptake to exposed animals have uptake rates in the following order: Pd>Pt>Rh. The liver and kidney accumulate the highest levels of PGE, especially Pd. Urinary Pd and Rh, but not Pt, levels are correlated with traffic intensity. Dental alloys may lead to elevated urinary Pt levels

  17. Methods for the determination of platinum group elements originating from the abrasion of automotive catalytic converters

    NASA Astrophysics Data System (ADS)

    Bencs, László; Ravindra, Khaiwal; Van Grieken, René

    2003-10-01

    Anthropogenic emission of platinum group elements (PGEs) from the abrasion of automotive catalytic converters into the environment has significantly increased. However, the concentration level of these PGEs (i.e. Pd, Pt, Rh) is still very low in the nature. Accordingly, their determination and speciation in various environmental compartments appears to be a challenging task for analytical chemists. The present review gives an overview of the analytical procedures documented in this particular field of analytical chemistry with a distinctive emphasis on spectrochemical methodology, it being the most sensitive and robust for accomplishing the above analytical task.

  18. Characterization of the Sukinda and Nausahi ultramafic complexes, Orissa, India by platinum-group element geochemistry

    USGS Publications Warehouse

    Page, N.J.; Banerji, P.K.; Haffty, J.

    1985-01-01

    Samples of 20 chromitite, 14 ultramafic and mafic rock, and 9 laterite and soil samples from the Precambrian Sukinda and Nausahi ultramafic complexes, Orissa, India were analyzed for platinum-group elements (PGE). The maximum concentrations are: palladium, 13 parts per billion (ppb); platinum, 120 ppb; rhodium, 21 ppb; iridium, 210 ppb; and ruthenium, 630 ppb. Comparison of chondrite-normalized ratios of PGE for the chromitite samples of lower Proterozoic to Archean age with similar data from Paleozoic and Mesozoic ophiolite complexes strongly implies that these complexes represent Precambrian analogs of ophiolite complexes. This finding is consistent with the geology and petrology of the Indian complexes and suggests that plate-tectonic and ocean basin developement models probably apply to some parts of Precambrian shield areas. ?? 1985.

  19. Platinum-group element geochemistry of zoned ultramafic intrusive suites, Klamath Mountains, California and Oregon.

    USGS Publications Warehouse

    Gray, F.; Page, N.J.; Carlson, C.A.; Wilson, S.A.; Carlson, R.R.

    1986-01-01

    Analyses for platinum-group elements of the varied rock suites of three Alaskan-type ultramafic to mafic multi-intrusive bodies are reported. Ir and Ru are less than analytical sensitivities of 100 and 20 ppb; Rh is less than or near 1 ppb. Average Pd assays vary among the rocks within intrusive complexes and between the three complexes (6.3, 13.7, 36.4 ppb); average Pt assays vary little among the same samples (27.9, 60.9, 34.0 ppb). Statistically adjusted Pt/(Pt + Pd) ratios increase in each suite from gabbro through clinopyroxenite to olivine-rich rocks, possibly owing to Pd fractionation.-G.J.N.

  20. Geophysical Imaging of the Stillwater and Bushveld Complexes and Relation to Platinum-group Element Exploration

    NASA Astrophysics Data System (ADS)

    Finn, C.; Bedrosian, P.; Zientek, M. L.; Cole, J.; Webb, S. J.; Bloss, B. R.

    2015-12-01

    Exploring for platinum-group elements (PGEs) relies on understanding the geophysical signature of the entire magmatic system in which they form, from bottom to top. New potential field and electromagnetic data and methods effectively map internal structures of layered intrusions that host PGE-bearing magmatic ore deposits, the volume of the intrusion and its extent under cover, and locations of sulfide mineralization. High resolution aeromagnetic data can image fine scale linear anomalies related to layering in the Stillwater and Bushveld Complexes. At Stillwater, the aeromagnetic anomalies relate to boundaries between major stratigraphic units and olivine-bearing rock layers altered to a mixture of serpentine and magnetite. The PGE-enriched sulfide mineralization hosted by olivine-bearing rocks in the Stillwater Complex produces a distinct linear magnetic high. In the Upper Zone of the Bushveld Complex, primary magnetite layers generate linear magnetic highs. Electromagnetic (EM) data over the Stillwater Complex highlight contact-type mineralization which contain low resistivity sulfide minerals. Stochastic inversions reveal a low resistivity zone along the southern edge of the Stillwater Complex corresponding to mineralization in banded iron formation or contact-type sulfide mineralization in the Basal zone. Gravity highs characterize the exposed and interpreted buried extent of the Stillwater and Bushveld complexes. A 3D inversion of gravity data of the Sillwater Complex indicates that the complex extends 30 km north and 40 km east of its outcrop beneath Phanerozoic cover. Geophysical models image the 3D geometry of the Bushveld Complex north of the Thabazimbi-Murchison Lineament (TML), critical for understanding the origin of the world's largest layered mafic intrusion and associated platinum- group element deposits, as a ~4 km thick, 160 km x ~125 km body underlying ~1-2 km of cover. Locally thick regions in the TML portion of the model may represent feeders

  1. Platinum-group element systematics and petrogenetic processing of the continental upper mantle: A review

    NASA Astrophysics Data System (ADS)

    Lorand, Jean-Pierre; Luguet, Ambre; Alard, Olivier

    2013-04-01

    The platinum-group element (PGE) systematics of continental mantle peridotites show large variability, reflecting petrogenetic processing of the upper mantle during partial melting and melt/fluid percolation inside the lithosphere. By removing Pd-Cu-Ni rich sulfides, partial melting events that have stabilized the sub-continental mantle lithosphere fractionated PPGEs (Palladium-group PGE; Pt, Pd) relative to IPGEs (Iridium-group PGE; Os, Ir, Ru, Rh). Residual base-metal sulfides (BMS) survive as enclosed IPGE-enriched Monosulfide Solid Solutions (Mss), which otherwise decompose into Ru-Os-Ir-rich refractory platinum-group minerals (PGMs) once the partial melts become S-undersaturated. The small-scale heterogeneous distribution of these microphases may cause extreme nugget effects, as seen in the huge variations in absolute PGE concentrations documented in cratonic peridotites. Magmas fluxing through the lithospheric mantle may change the initial PGE budgets inherited from the melting events, resulting in the great diversity of PGE systematics seen in peridotites from the sub-continental lithosphere. For instance, melt-rock reactions at increasing melt/rock ratios operate as open-system melting processes removing residual BMS/PGMs. Highly percolated peridotites are characterized by extreme PGE depletion, coupled with PGE patterns and Os-isotope compositions that gradually evolve toward that of the percolating melt. Reactions at decreasing melt-rock ratios (usually referred to as «mantle metasomatism») precipitate PPGE-enriched BMS that yield suprachondritic Pd/Ir and occasionally affect Pt/Ir and Rh/Ir ratios as well. Moreover, volatile-rich, small volume melts fractionate Os relative to Ir and S relative to Se, thereby producing rocks with supra-chondritic Os/Ir and S/Se coupled with supra-chondritic Pd/Ir and Pt/Ir. Major magmatic inputs at the lithosphere-asthenosphere boundary may rejuvenate the PGE systematics of the depleted mantle. Integrated studies of

  2. Partitioning of Si and platinum group elements between liquid and solid Fe-Si alloys

    NASA Astrophysics Data System (ADS)

    Morard, G.; Siebert, J.; Badro, J.

    2014-05-01

    Crystallization of the Earth's inner core fractionates major and minor elements between the solid and liquid metal, leaving physical and geochemical imprints on the Earth's core. For example, the density jump observed at the Inner Core Boundary (ICB) is related to the preferential partitioning of lighter elements in the liquid outer core. The fractionation of Os, Re and Pt between liquid and solid during inner core crystallization has been invoked as a process that explains the observed Os isotopic signature of mantle plume-derived lavas (Brandon et al., 1998; Brandon and Walker, 2005) in terms of core-mantle interaction. In this article we measured partitioning of Si, Os, Re and Pt between liquid and solid metal. Isobaric (2 GPa) experiments were conducted in a piston-cylinder press at temperatures between 1250 °C and 1600 °C in which an imposed thermal gradient through the sample provided solid-liquid coexistence in the Fe-Si system. We determined the narrow melting loop in the Fe-Si system using Si partitioning values and showed that order-disorder transition in the Fe-Si solid phases can have a large effect on Si partitioning. We also found constant partition coefficients (DOs, DPt, DRe) between liquid and solid metal, for Si concentrations ranging from 2 to 12 wt%. The compact structure of Fe-Si liquid alloys is compatible with incorporation of Si and platinum group elements (PGEs) elements precluding solid-liquid fractionation. Such phase diagram properties are relevant for other light elements such as S and C at high pressure and is not consistent with inter-elemental fractionation of PGEs during metal crystallization at Earth's inner core conditions. We therefore propose that the peculiar Os isotopic signature observed in plume-derived lavas is more likely explained by mantle source heterogeneity (Meibom et al., 2002; Baker and Krogh Jensen, 2004; Luguet et al., 2008).

  3. Levels of platinum group elements and rare-earth elements in wild mushroom species growing in Poland.

    PubMed

    Mleczek, Mirosław; Niedzielski, Przemysław; Kalač, Pavel; Siwulski, Marek; Rzymski, Piotr; Gąsecka, Monika

    2016-01-01

    Due to limited data-describing abilities of mushrooms to accumulate platinum group elements (PGEs) and rare-earth elements (REEs), the aim of this study was to determine, by inductively coupled plasma optical emission spectrometry followed by microwave-assisted sample digestion by nitric acid, the content of these elements in 20 mushroom species (10 above ground and 10 growing on wood), mostly edible, collected near a busy trunk road. The highest content of PGEs in above-ground mushroom species was observed in Lepista gilva and Suillus bovinus fruit bodies (0.38 ± 0.05 and 0.37 ± 0.03 mg kg(-1) DW, respectively), while in mushrooms growing on wood, the highest content was observed in Pleurotus ostreatus (0.35 ± 0.04 mg kg(-1) DW). The mean content of PGEs for both these groups was 0.23 ± 0.08 and 0.26 ± 0.07 mg kg(-1) DW, respectively. The highest content of REEs in Suillus luteus and Tricholoma equestra was 5.03 ± 0.50 and 2.18 ± 0.56 mg kg(-1) DW, respectively, but within mushrooms growing on wood in Ganoderma applanatum fruiting bodies it was 4.19 ± 0.78 mg kg(-1) DW. Mean contents of REEs were 1.39 ± 1.21 and 1.61 ± 0.97 mg kg(-1) DW in above-ground species and species growing on wood, respectively. Generally, the group of mushroom species growing on wood was capable of slightly higher accumulation of both REEs and PGEs. No limits have been established for both the groups until now. PMID:26515437

  4. [Pollution characteristics of platinum group elements in road dust in central urban area of Beijing].

    PubMed

    Xu, Ling-Ling; Gao, Bo; Lu, Jin; Zhou, Huai-Dong; Hao, Hong; Wang, Xiao-Jun

    2011-03-01

    In order to survey platinum group elements (PGEs) contamination in central urban area of Beijing, dust samples were collected from the second ring road in December 2009. The road samples were digested with aqua regia and separated and purified with cation exchange resin, and the resulting solutions were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the concentrations of Pd, Pt and Rh in road dust ranged from 17.40-458.75 ng x g(-1) (126.66 ng x g(-1)), 10.04-182.89 ng x g(-1) (65.25 ng x g(-1)), 4.00-68.04 ng x g(-1) (22.67 ng x g(-1)) respectively. In comparison with international cities, Pd and Rh concentrations in Beijing road dust were middle level and Pt concentration was lower. Pd concentration was rapidly increased in recent years. The concentrations of PGEs in four locations of the second ring road were arranged in the following order: West approximately East > North > South, which were controlled with the traffic intensity. Size partitioning indicated that the 0.125-0.25 mm fraction had the higher PGEs concentrations than other fractions and the < 0.063 mm fraction had the lower PGEs concentration. These data suggest that autocatalyst PGEs flux estimates into the environment will be significantly underestimated if only a fine grain size fraction (< 0.063 mm) is analyzed. PMID:21634172

  5. Potential mobilization of platinum-group elements by siderophores in surface environments.

    PubMed

    Dahlheimer, Susan R; Neal, Clive R; Fein, Jeremy B

    2007-02-01

    The emission of platinum-group elements (PGEs) from catalytic converters has led to increased environmental abundances of Pt, Pd, and Rh; however, little is known about the environmental effects and fate of these metals. Organic ligands found in soils have the potential to increase the mobility of PGEs and potentially increase the bioavailability of the metals. Here, we assessed the abilities of microbially produced iron-chelating ligands (siderophores) to complex with the PGEs. Batch experiments using the synthetic siderophore desferrioxamine-B (DFO-B) and powdered metal or oxide forms of Pt, Pd, or Rh showed that DFO-B enhances the solubility of Pt and Pd due to the formation of Pt- and Pd-DFO-B aqueous complexes, with estimated minimum stability constants on the order of 10(17-18) and 10(20-24), respectively. Dissolution rates for Pd are comparable to other mineral dissolution rates with DFO-B. DFO-B had little to no effect on the dissolution of Rh metal or Rh2O3. Our results indicate that siderophores have the potential to increase the mobility of Pt and Pd in environments with limited activities of free trivalent cations. These results have implications for the fate of catalytic converter-emitted Pt and Pd, and support the need for further Pt and Pd toxicity and bioaccumulation studies. PMID:17328196

  6. New SSMS Techniques for the Determination of Rhodium and Other Platinum- Group Elements in Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Jochum, K. P.; Seufert, H. M.

    1995-09-01

    We have developed new spark source mass spectrometric (SSMS) techniques for simultaneous analysis of platinum-group elements (PGE) together with other trace elements in stony meteorites. We have measured elemental abundances of Rh, Ru, Os, Ir, Pt, Au in carbonaceous chondrites of different types including the two CI chondrites Orgueil and Ivuna. These data are relevant for the determination of solar-system abundances. Whereas the solar-system abundances of most PGE are well known, this is not the case for Rh, and no literature data exist for carbonaceous chondrites, mainly because of analytical difficulties. The SSMS techniques include new calibration procedures and the use of a recently developed multi-ion counting (MIC) system [1]. The mono-isotopic element Rh and the other PGE were determined by using internal standard elements (e.g., Nd, U) that were measured by isotope dilution in the same sample electrode material. The data were calibrated with certified standard solutions of PGE which were doped on trace-element poor rock samples. Ion abundances were measured using both the conventional photoplate detection and the ion-counting techniques. The new MIC technique that uses up to 20 small channeltrons for ion counting measurements has the advantage of improved precision, detection limits and analysis time compared to photoplate detection. Tab. 1 shows the Rh analyses for the meteorites Orgueil, Ivuna, Murchison, Allende and Karoonda obtained by conventional photoplate detection. These are the first Rh results for carbonaceous chondrites. The data for the two CI chondrites Orgueil and Ivuna are identical and agree within 4 % with the CI estimate of Anders and Grevesse [2] which was derived indirectly from analyses for H-chondrites. The PGE Os, Ir, Pt, Au and W, Re, Th, U concentrations were determined by both detection systems. Data obtained with the MIC system are more precise (about 4% for concentrations in the ppb range) compared to the photoplate detection

  7. Separating Continental Mineral Dust from Cosmic Dust using Platinum Group Element Concentrations and Osmium Isotopes in Ancient Polar Ice

    NASA Astrophysics Data System (ADS)

    Seo, J. H.; Jackson, B.; Osterberg, E. C.; Sharma, M.

    2015-12-01

    The platinum group element (PGEs: Pt, Pd, Rh, Ir, Os, and Ru) accumulation in ancient polar archives have been argued to trace cosmic dust and "smoke" from larger meteors but the PGE concentration data lack specificity. For example, the extent to which the terrestrial volcanism/dust has contributed to the PGE inventory of polar ice cannot be readily evaluated. Since the Os isotope compositions (187Os/188Os ratio) of the terrestrial and extraterrestrial sources are distinctly different from each other, the PGE concentrations when combined with Os isotope composition have the potential to untangle contributions from these sources. Platinum group element concentration determinations in polar ice cores are highly challenging due to their extremely low concentrations (down to 10-15 g/g or fg/g). Here, a new procedure is presented that allows PGEs and Os isotope compositions to be determined from a ~50 g sample of polar ice. Decontaminated ice-melt is spiked with 101Ru, 106Pd, 190Os, 191Ir, and 198Pt and frozen at -20 °C in quartz-glass ampoules. A mixture of purified HNO3 and H2O2 is then added and the sample is heated to 300 °C at 128bar using a High Pressure Asher. This allows all spikes to be equilibrated with the sample PGEs and all Os species are oxidized to OsO4. The resulting OsO4 is extracted using distillation, purified, and measured using negative thermal ionization mass spectrometry. PGEs are then separated and purified using two stage column chromatography and their concentrations determined by isotope dilution using a triple quadruople inductively coupled plasma mass spectrometer coupled to an Apex de-solvation nebulizer. The developed method was applied to modern Greenland firn and snow. The PGE concentrations of the firn are 4.0 fg/g for Ir, 20 fg/g for Ru, 590 fg/g for Pt, 38 fg/g for Pd, and 1.3 fg/g for Os, while those of the snow are 3.0 fg/g for Ir, 53 fg/g for Ru, 360 fg/g for Pt, 32 fg/g for Pd, and 0.4 fg/g for Os, respectively. A comparison

  8. Airborne particulate matter, platinum group elements and human health: a review of recent evidence.

    PubMed

    Wiseman, Clare L S; Zereini, Fathi

    2009-04-01

    Environmental concentrations of the platinum group elements (PGE) platinum (Pt), palladium (Pd) and rhodium (Rh) have been on the rise, due largely to the use of automobile catalytic converters which employ these metals as exhaust catalysts. It has generally been assumed that the health risks associated with environmental exposures to PGE are minimal. More recent studies on PGE toxicity, environmental bioavailability and concentrations in biologically relevant media indicate however that environmental exposures to these metals may indeed pose a health risk, especially at a chronic, subclinical level. The purpose of this paper is to review the most recent evidence and provide an up-to-date assessment of the risks related to environmental exposures of PGE, particularly in airborne particulate matter (PM). This review concludes that these metals may pose a greater health risk than once thought for several reasons. First, emitted PGE may be easily mobilised and solubilised by various compounds commonly present in the environment, thereby enhancing their bioavailability. Second, PGE may be transformed into more toxic species upon uptake by organisms. The presence of chloride in lung fluids, for instance, may lead to the formation of halogenated PGE complexes that have a greater potential to induce cellular damage. Third, a significant proportion of PGE found in airborne PM is present in the fine fraction that been found to be associated with increases in morbidity and mortality. PGE are also a concern to the extent that they contribute to the suite of metals found in fine PM suspected of eliciting a variety of health effects, especially in vulnerable populations. All these factors highlight the need to monitor environmental levels of PGE and continue research on their bioavailability, behaviour, speciation and associated toxicity to enable us to better assess their potential to elicit health effects in humans. PMID:19181366

  9. [Pollution characteristics of platinum group elements in road rust in Xiamen].

    PubMed

    Hong, Zhen-yu; Hong, You-wei; Yin, Li-qian; Chen, Jin-sheng; Chen, Yan-ting; Xu, Ling-ling

    2015-01-01

    With the potential risks for the environment and human health, the concentration and distribution characteristics of platinum group element(PGEs) in road dust in Xiamen city were investigated. Road dust samples were collected from the traffic trunk road, tunnel, tourism area, and industrial area of Xiamen on October 2012. The samples were digested with aqua regia in a microwave assisted digestion system under high pressure condition, separated and purified with cation exchange resin( Dowex AG50W-X8), and the resulting solutions were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the average concentrations(range) of Pd, Pt and Rh in road dust were 246.82 (58.68-765.52) ng x g(-1), 95.45 (42.14-371.36) ng x g(-1) and 51.76 (21.04-119.72) ng x g(-1), respectively, which were two orders of magnitude higher than the background values. Compared with other cities worldwide, the concentrations of Pd, Pt and Rh in road dust in Xiamen were at higher levels. Theconcentrations of PGEs for different functional areas were listed in the following order: tunnel > urban district > industrial area > tourism area, which indicated that their spatial distributions were mainly affected by the traffic intensity. Correlation analysis results showed that concentration of Pd in the urban traffic artery was significantly correlated with Rh, while Pt was not so correlated with Pd and Rh, suggesting that other sources contributed to PGEs in road dust in addition to the vehicle emission. Although motor vehicle traveling was banned in tourist area, the concentration of PGEs was still at a high level. Some of them might originate from the road dust in surrounding area by atmosphere diffusion. PMID:25898678

  10. [Migration and transformation of anthropogenic platinum group elements in environment: a review].

    PubMed

    Li, Pei-Miao; Gao, Xue-Lu

    2012-12-01

    Anthropogenic platinum group elements (PGEs) are widely applied in vehicle exhaust catalytic converters (VECs), industrial catalysts, and pharmaceutics, making the PGEs, especially Pt, Pd, and Rh, become the newly environmental pollutants in some fields. Given the positive correlations between the Pt/Pd and Pt/Rh ratios in various environmental samples and the active components of VECs, the VECs containing PGEs as catalysts are regarded as the primary source of PGEs pollution. Sufficient reports indicated that in the past three decades, there was a significant increase of PGEs concentrations in diverse environmental matrices like airborne particulate matters, aquatic ecosystem components (e.g., river water, rain water, groundwater, seawater, and sediments), soils, road dusts, and organisms. It was generally assumed that anthropogenic PGEs behave in inert manner, and the health risks associated with the environmental exposures to PGEs are minimal. However, the recent studies on PGEs toxicity and environmental bioavailability indicated that once entering environment, anthropogenic PGEs might easily be mobilized and transformed into more toxic forms under the actions of various biogeochemical processes, and thereby, enhanced their bioavailability and posed potential health risks to human beings through food chain. This paper summarized the research results about the sources, distribution, and biogeochemical behaviors of PGEs in various environmental media, and it was considered that to establish the standards of PGEs for human health risks, to develop standard substances of PGEs for environmental measurements, to study the PGEs in the sediments of marginal seas, and to assess the toxicity of PGEs to marine mollusks, the present contamination status of PGEs in foods, and the risks of PGEs to human health would be the hot research topics in the future. PMID:23479898

  11. Photochemistry and charge transfer chemistry of the platinum group elements. Progress report, May 1, 1991--April 30, 1992

    SciTech Connect

    Eisenberg, R.

    1991-12-01

    Significant progress has been made on the photochemistry and photophysics of platinum group element dithiolate complexes. The specific systems under investigation are square planar complexes of Pt(II) containing a dithiolate chelate and two other donor groups to complete the coordination sphere. The donor groups may be amines, imines, phosphines, phosphites or olefins, and they can be either monodentate or joined together as part of a chelate ring.

  12. High salinity volatile phases in magmatic Ni-Cu-platinum group element deposits

    NASA Astrophysics Data System (ADS)

    Hanley, J. J.; Mungall, J. E.

    2004-12-01

    The role of "deuteric" fluids (exsolved magmatic volatile phases) in the development of Ni-Cu-PGE (platinum group element) deposits in mafic-ultramafic igneous systems is poorly understood. Although considerable field evidence demonstrates unambiguously that fluids modified most large primary Ni-Cu-PGE concentrations, models which hypothesize that fluids alone were largely responsible for the economic concentration of the base and precious metals are not widely accepted. Determination of the trace element composition of magmatic volatile phases in such ore-forming systems can offer considerable insight into the origin of potentially mineralizing fluids in such igneous environments. Laser ablation ICP-MS microanalysis allows researchers to confirm the original metal budget of magmatic volatile phases and quantify the behavior of trace ore metals in the fluid phase in the absence of well-constrained theoretical or experimental predictions of ore metal solubility. In this study, we present new evidence from major deposits (Sudbury, Ontario, Canada; Stillwater Complex, Montana, U.S.A.) that compositionally distinct magmatic brines and halide melt phases were exsolved from crystallizing residual silicate melt and trapped within high-T fluid conduits now comprised of evolved rock compositions (albite-quartz graphic granite, orthoclase-quartz granophyre). Petrographic evidence demonstrates that brines and halide melts coexisted with immiscible carbonic phases at the time of entrapment (light aliphatic hydrocarbons, CO2). Brine and halide melt inclusions are rich in Na, Fe, Mn, K, Pb, Zn, Ba, Sr, Al and Cl, and homogenize by either halite dissolution at high T ( ˜450-700° C) or by melting of the salt phase (700-800° C). LA-ICPMS analyses of single inclusions demonstrate that high salinity volatile phases contained abundant base metals (Cu, Fe, Sn, Bi) and precious metals (Pt, Pd, Au, Ag) at the time of entrapment. Notably, precious metal concentrations in the inclusions

  13. Platinum-group elements: quantification in collected exhaust fumes and studies of catalyst surfaces.

    PubMed

    Palacios, M A; Gómez, M M; Moldovan, M; Morrison, G; Rauch, S; Mcleod, C; Ma, R; Laserna, J; Lucena, P; Caroli, S; Alimonti, A; Petrucci, F; Bocca, B; Schramel, P; Lustig, S; Zischka, M; Wass, U; Stenbom, B; Luna, M; Saenz, J C; Santamaría, J; Torrens, J M

    2000-07-20

    Automotive catalytic converters, in which Pt, Pd and Rh (platinum-group elements; PGEs) are the active components for eliminating several noxious components from exhaust fumes, have become the main source of environmental urban pollution by PGEs. This work reports on the catalyst morphology through changes in catalyst surface by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) and laser-induced breakdown spectrometry (LIBS) from fresh to aged catalytic converters. The distribution of these elements in the fresh catalysts analysed (Pt-Pd-Rh gasoline catalyst) is not uniform and occurs mainly in a longitudinal direction. This heterogeneity seems to be greater for Pt and Pd. PGEs released by the catalysts, fresh and aged 30,000 km, were studied in parallel. Whole raw exhaust fumes from four catalysts of three different types were also examined. Two of these were gasoline catalysts (Pt-Pd Rh and Pd-Rh) and the other two were diesel catalysts (Pt). Samples were collected following the 91,441 EUDC driving cycle for light-duty vehicle testing. The results show that at 0 km the samples collected first have the highest content of particulate PGEs and although the general tendency is for the release to decrease with increasing number of samples taken, exceptions are frequent. At 30,000 km the released PGEs in gasoline and diesel catalysts decreased significantly. For fresh gasoline catalysts the mean of the total amount released was approximately 100, 250 and 50 ng km(-1) for Pt, Pd and Rh, respectively. In diesel catalysts the Pt release varied in the range 400-800 ng km-1. After ageing the catalysts up to 30,000 km, the gasoline catalysts released amounts of Pt between 6 and 8 ng km(-1), Pd between 12 and 16 ng km(-1) and Rh between 3 and 12 ng km(-1). In diesel catalysts the Pt release varied in the range 108-150 ng km(-1). The soluble portion of PGEs in the HNO3 collector solution represented less than 5% of the total amount for fresh catalysts

  14. Platinum group elements in a 3.5 Ga nickel-iron occurrence - Possible evidence of a deep mantle origin

    NASA Technical Reports Server (NTRS)

    Tredoux, Marian; Hart, Rodger J.; Lindsay, Nicholas M.; De Wit, Maarten J.; Armstrong, Richard A.

    1989-01-01

    This paper reports the results of new field observations and the geochemical analyses for the area of the Bon Accord (BA) (the Kaapvaal craton, South Africa) Ni-Fe deposit, with particular consideration given to the trace element, platinum-group element, and isotopic (Pb, Nd, and Os) compositions. On the basis of these data, an interpretation of BA is suggested, according to which the BA deposit is a siderophile-rich heterogeneity remaining in the deep mantle after a process of incomplete core formation. The implications of such a model for the study of core-mantle segregation and the geochemistry of the lowermost mantle are discussed.

  15. Environmental risk of particulate and soluble platinum group elements released from gasoline and diesel engine catalytic converters.

    PubMed

    Moldovan, M; Palacios, M A; Gómez, M M; Morrison, G; Rauch, S; McLeod, C; Ma, R; Caroli, S; Alimonti, A; Petrucci, F; Bocca, B; Schramel, P; Zischka, M; Pettersson, C; Wass, U; Luna, M; Saenz, J C; Santamaría, J

    2002-09-16

    A comparison of platinum-group element (PGE) emission between gasoline and diesel engine catalytic converters is reported within this work. Whole raw exhaust fumes from four catalysts of three different types were examined during their useful lifetime, from fresh to 80,000 km. Two were gasoline engine catalysts (Pt-Pd-Rh and Pd-Rh), while the other two were diesel engine catalysts (Pt). Samples were collected following the 91441 EUDC driving cycle for light-duty vehicle testing, and the sample collection device used allowed differentiation between the particulate and soluble fractions, the latter being the most relevant from an environmental point of view. Analyses were performed by inductively coupled plasma-mass spectrometry (ICP-MS) (quadrupole and high resolution), and special attention was paid to the control of spectral interference, especially in the case of Pd and Rh. The results obtained show that, for fresh catalysts, the release of particulate PGE through car exhaust fumes does not follow any particular trend, with a wide range (one-two orders of magnitude) for the content of noble metals emitted. The samples collected from 30,000-80,000 km present a more homogeneous PGE release for all catalysts studied. A decrease of approximately one order of magnitude is observed with respect to the release from fresh catalysts, except in the case of the diesel engine catalyst, for which PGE emission continued to be higher than in the case of gasoline engines. The fraction of soluble PGE was found to represent less than 10% of the total amount released from fresh catalysts. For aged catalysts, the figures are significantly higher, especially for Pd and Rh. Particulate PGE can be considered as virtually biologically inert, while soluble PGE forms can represent an environmental risk due to their bioavailability, which leads them to accumulate in the environment. PMID:12398337

  16. Mobilization of the platinum group elements by low-temperature fluids: Implications for mineralization and the iridium controversy

    NASA Technical Reports Server (NTRS)

    Dowling, Kim; Keays, Reid R.; Wallace, Malcolm W.; Gostin, Victor A.

    1992-01-01

    Geochemical investigations on the widely dispersed Late Proterozoic Acraman impact ejecta horizon and its host marine shales in the Adelaide Geosyncline provide strong evidence for low-temperature mobilization of the platinum group elements (PGE), including Ir. The ejecta horizon was formed when the middle Proterozoic dacitic volcanics in the Gawler Ranges, central South Australia, were impacted by a very large (ca. 4 km) meteorite. The resulting structure, now represented by Lake Acraman, is Australia's largest meteorite impact structure. Debris from the impact was blasted for many hundreds of kilometers, some falling into the shallow sea of the Adelaide Geosyncline, some 300 km to the east of the impact site.

  17. Osmium-Isotope and Platinum-Group-Element Systematics of Impact-Melt Rocks, Chesapeake Bay Impact Structure, Virginia, USA

    NASA Technical Reports Server (NTRS)

    Lee, Seung Ryeol; Wright Horton, J., Jr.; Walker, Richard J.

    2005-01-01

    Osmium (Os) isotopes and platinum-group elements (PGEs) are useful for geochemically identifying a meteoritic component within impact structures, because meteorites are typically characterized by low (187)Os/(188)Os ratios and high PGE concentrations. In contrast, most types of crustal target rocks have high radiogenic Os and very low PGE concentrations. We have examined Os isotope and PGE systematics of impact-melt rocks and pre-impact target rocks from a 2004 test hole in the late Eocene Chesapeake Bay impact structure and from nearby coreholes. Our goal is to determine the proportion of the projectile component in the melt rock Additional information is included in the original extended abstract.

  18. Finding of probable Tunguska Cosmic Body material: anomalies in platinum group elements in peat from the explosion area

    NASA Astrophysics Data System (ADS)

    Kolesnikov, E. M.; Hou, Q. L.; Xie, L. W.; Kolesnikova, N. V.

    2005-04-01

    Further evidencies of a cometary nature of the 1908 Tunguska Cosmic Body (TCB) are presented. Earlier in the event layers of the Sphagnum fuscum peat from the explosion area, anomalies, relative to Earth-materials, of the elements H, C, and N—all abundant in comets—have been found [E.W. Kolesnikov, T. Boettger and N.V. Kolesnikova, Planet. Space Sci. 47 905 (1999); E.M. Kolesnikov, G. Longo, T. Boettger, N.V. Kolesnikova, P. Gioacchini, L. Forlani, R. Giampieri and R. Serra, Icarus 161 235 (2003).]. At the present work we revealed a sharp increase of concentrations of platinum group elements (PGE), REE and other elements in the event layers as well. Their ratios point to a cometary nature of the anomalies observed.

  19. pH-dependent release of trace elements including platinum group elements (PGEs) from gasoline and diesel catalysts

    NASA Astrophysics Data System (ADS)

    Sucha, Veronika; Mihaljevic, Martin; Ettler, Vojtech; Strnad, Ladislav

    2014-05-01

    The release of trace metals and platinum group elements (PGEs) from automobile exhaust catalysts represents a remarkable source of higly dispersed environmental contamination. Especially, PGEs have shown increasing research interest due to their possible bioaccessibility. In our research, we focused on leaching behaviour of trace metals from gasoline and diesel automobile catalysts. While catalysts for gasoline engines contain a mixture of Pt-Pd-Rh or Pd-Rh, catalysts for diesel engines are composed only of Pt. We used dust from two crushed gasoline and two crushed diesel catalysts (new and aged). The dust of gasoline catalysts contains significant concentrations of Pt (700 mg.kg-1), Pd (11 000 mg.kg-1) and Rh (700 mg.kg-1). And the dust of diesel catalysts are composed of Pt (3 900 mg.kg-1) and they contains negligible amounts of Pd dan Rh (< 0.5 mg.kg-1, < 0.1 mg.kg-1, respectively). To evaluate leaching of trace metals from dust we used pH-stat leaching test according to the European standard CEN/TS 14997. The concentrations of cations: PGEs (Pt, Pd a Rh), K, Na, Ca, Mg, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, La and Ce were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), and anions: F-, Cl-, SO42- and NO3- by high-performance liquid chromatography. Although the dusts from catalysts were relatively stable to acid/base influence, the leaching of trace metals from catalysts showed a dependence on pH. Generally, the highest concentrations were released under acidic conditions. The leaching of PGEs was higher for Pt in diesel catalysts and for Pd and Rh in gasoline catalysts. The highest concentrations of Zn and Pb were observed in old catalysts. The rare earth metals were released more from gasoline catalysts. Catalysts particles represent health risk especially with respect to their PGEs contents.

  20. Contrasting Platinum-Group Element and Chalcophile Element Contents in Pyrrhotite, Pentlandite and Chalcopyrite From Different Environments

    NASA Astrophysics Data System (ADS)

    Barnes, S.-; Dare, S. A.

    2009-05-01

    It is now possible to determine the platinum-group element (PGE) and chalcophile element contents of pyrrhotite (Po), pentlandite (Pn) and chalcopyrite (Ccp). This information may be used to: a) Improve recovery of important economic elements from ore; b) Consider the petrogenesis of the rocks. We have determined the PGE and other chalcophile element contents of Po, Pn and Ccp from a meteorite, a subvolcanic sill, the Merensky Reef Bushveld, Great Dyke, JM Reef Stillwater, AP and PV Reefs Penikat and Creighton Mine at Sudbury. The aims of these studies are to determine which phases host the elements and what implications the host phases have for the petrogenesis of the rocks involved. Sulfides from the meteorite and the subvolcanic sill have been chilled fairly rapidly and experienced very little subsolidus re-equilibration. The Bushveld and Great Dyke sulfides cooled slowly and thus had longer to exsolve. The Stillwater and Penikat sulfides were metamorphosed post-intrusion thus these sulfides have been reheated. The Sudbury sulfides have been deformed and metamorphosed and are the major phases whereas in all other cases the sulfides were minor phases in the rocks. In all cases Pt and Au are not present in the sulfides. Platinum is generally found as Pt-arsenides, Pt-bismuth- tellurides or Pt-alloys as inclusions in the sulfides. Palladium is generally hosted principally by Pn. Osmium and Ru are present in Po and Pn. In the meteorite, the subvolcanic sill and the unmetamorphosed intrusions Re, Ir and Rh are also present in Po and Pn. However in the metamorphosed and deformed sulfides Ir and Rh are present largely as sulfarsenides and as various Re minerals included in the sulfides. Thus in the least metamorphosed and deformed rocks all the PGE except Pt are present in the sulfides. In the metamorphosed rocks Re, Ir and Rh tend to form inclusions in the sulfides. We suggest that this is the result of exsolution during reworking of the sulfides. The concentration of

  1. Platinum-group elements in rocks from the voikar-syninsky ophiolite complex, Polar Urals, U.S.S.R.

    USGS Publications Warehouse

    Page, N.J.; Aruscavage, P. J.; Haffty, J.

    1983-01-01

    Analyses of platinum-group elements (PGE) in rocks collected from the Voikar-Syninsky ophiolite in the Polar Urals suggest that the distribution and geochemistry of PGE in this Paleozoic ophiolite are similar to those in Mesozoic ophiolites from elsewhere. Chondrite-normalized PGE patterns for chromitite, the tectonite unit, and ultramafic and mafic cumulate unit have negative slopes. These results are similar to those found for chromitites from other ophiolites; stratiform chromities show positive slopes. If the magmas that form both types of chromitite originate from similar mantle source material with respect to PGE content, the processes involved must be quite different. However, the distinct chondrite-normalized PGE patterns may reflect differing source materials. ?? 1983 Springer-Verlag.

  2. Distribution of the platinum group elements in peat deposit near a historic lead and silver mining district.

    PubMed

    Strnad, Ladislav; Mihaljevic, Martin; Ettler, Vojtech; Barsová, Linda; Zuna, Milan; Sebek, Ondrej

    2008-08-01

    Concentrations of platinum group elements (PGE) and Ag were studied in a minerotrophic peat deposit near a historic Pb-Ag mining district (Príbram, Czech Republic). The PGE determinations were performed by quadrupole ICP-MS after NiS fire assay procedure. In the individual peat layers (dated by measurement of (210)Pb activity) the PGE concentrations were low and ranged from 0.015 ng g(-1) (Ir) to 11.8 ng g(-1) (Pt). The enrichment of PGE (especially Pt) compared to the Earth crust contents were observed during two periods. The peak in the second half of 19th century was explained by massive increase of ore mining and affinity of PGE to concentrate in molten lead during Pb processing. The recent PGE enrichment in peat layers might be explained by automobile (with catalytic converters) exhaust fumes or processing of computer electronic parts by the smelter. PMID:18373043

  3. Platinum in the environment: frequency of reactions to platinum-group elements in patients with dermatitis and urticaria.

    PubMed

    Santucci, B; Valenzano, C; de Rocco, M; Cristaudo, A

    2000-12-01

    The aim of the present paper is to evaluate whether increasing environmental exposure increases the frequency of the positive prick and patch test reactions to certain chlorinated platinum salts in patients with dermatitis and urticaria. 800 consecutive subjects with contact dermatitis (n=749) and urticaria (n=51) were variously patch and prick tested with 30 haptens of a standard series, with aqueous solutions of, respectively, hexachloroplatinic acid (H2[PtCl6]), potassium tetrachloroplatinate (K2[PtCl4]), sodium hexachloroplatinate (Na2[PtCl6]), iridium chloride (IrCl3), rhodium chloride (RhCl3) and palladium chloride (PdCl2), and with 16 common inhalants. 153 workers, variably exposed in a platinum refinery, were patch and prick tested only with solutions containing platinum-group elements at various concentrations and with 16 common inhalants. Platinum-group elements did not elicit positive patch or prick test reactions in non-occupationally exposed subjects. In contrast, in exposed workers, positive patch test reactions at day 2 and at 25 min, respectively, were found in 2 subjects with hand dermatitis and in 2 with urticaria and asthma. 22 out of the 153 workers, 18 of whom had rhinitis, asthma, and urticaria, gave positive prick test reactions to 1 or more salts. Furthermore, on patch and prick testing, 4 cross-reactions between platinum, palladium, iridium and rhodium were demonstrated. In conclusion, the test results demonstrate that the present concentration in the environment does not increase the incidence of reactions to platinum salts in patients with dermatitis and/or urticaria. However, if the average level of environmental platinum exposure approaches those existing in industrial settings in the future, we are going to observe more frequent health effects. PMID:11140383

  4. Distribution of platinum-group elements in the Bati Kef chromite deposit, Guleman-Elazig area, eastern Turkey.

    USGS Publications Warehouse

    Page, N.J.; Engin, T.; Singer, D.A.; Haffty, J.

    1984-01-01

    The distribution of platinum-group elements (PGE) within chromite deposits from an ophiolite is determined and their geochemistry compared with chromitites from ophiolites and from stratiform layered complexes elsewhere in the world. The Guleman area chromitites are lenses of layered massive to disseminated chromite in dunite or sheared harzburgite along and near the dunite-harzburgite contact. PGE were analysed by a fire assay/spectrographic method. The analyses, in ppb, varied narrowly near the detection limits; only Ir was mostly detected (24-27 ppb) . The data plot as independent, slight variations of individual PGE with crude and irregular spatial distributions, oriented with respect to the land surface. Based on studies elsewhere, the PGE reside mostly in laurite, erlichmanite and Os/Ir alloys included within or interstitial to chromite. Average values for each PGE were normalized with respect to average chondrite concentrations for these elements. All patterns for ophiolite-chromitites (5) show depletion of these elements relative to chondrite average concentrations, with greater depletion in Pt and Pd than in Ir and Ru, to produce patterns with negative slopes. Chromitites from differentiated stratiform complexes (2) yield patterns with positive slopes. -G.J.N.

  5. Batch leaching tests of motherboards to assess environmental contamination by bromine, platinum group elements and other selected heavy metals.

    PubMed

    Almeida, César; Grosselli, Melina; González, Patricia; Martínez, Dante; Gil, Raúl

    2016-02-01

    In this study, a batch leaching test was executed to evaluate the toxicity associated with chemicals contained in motherboards. The leaching solutions used were distilled water, nitric acid, acetic acid and synthetic acid rain solution. A total of 21 elements including Ag, As, Au, Br, Cd, Co, Cr, Cu, Hf, Ir, Mn, Ni, Os, Pb, Pd, Pt, Rd, Rh, Se, U and Zn were analyzed. In this study, the pH values of all the leachates fell within the range of 2.33-4.88. The highest concentrations of metals were obtained from the acid rain solution, whilst the maximum value of bromine was achieved with solution of acetic acid. Appreciable concentrations of platinum group elements were detected with concentrations around 3.45, 1.43, 1.21 and 22.19 µg L(-1) for Ir, Pd, Pt and Rh, respectively. The different leaching of the motherboards revealed the predominant presence of the toxic substances in the leached from the e-waste. PMID:26343021

  6. Platinum group elements provide no indication of a meteoritic component in ICDP cores from the Bosumtwi crater, Ghana

    NASA Astrophysics Data System (ADS)

    Goderis, S.; Tagle, R.; Schmitt, R. T.; Erzinger, J.; Claeys, P. H.

    In an attempt to identify the type of projectile, 14 samples from the Bosumtwi crater in Ghana were analyzed for platinum group element (PGE) concentrations by nickel sulfide fire assay inductively coupled plasma-mass spectrometry (ICP-MS). The majority of the samples come from the impactite material recovered by cores LB-07A and LB-08A, which were drilled by the International Continental Scientific Drilling program (ICDP). One sample originates from the fallback material found at the contact between the impactite and the overlying lake sediment in core LB-05B. No clear signature of a meteoritic contamination was identified in the 13 impactite samples. The target rock apparently dominates the PGE contribution in the impactites. These results agree with the PGE concentrations reported for the suevites collected at the crater rim and in other parts of the Bosumtwi ICDP cores. However, based on Cr and Os isotopic signatures, a meteoritic component could be present in the sample of fallback material, supporting the reports of the existence of meteoritic material in the Ivory Coast tektites. Further analyses of the fallback material from the Bosumtwi drill cores should confirm (or not) this first result.

  7. Osmium isotopic compositions of Os-rich platinum group element alloys from the Klamath and Siskiyou Mountains

    NASA Astrophysics Data System (ADS)

    Meibom, Anders; Frei, Robert; Sleep, Norman H.

    2004-02-01

    We present new measurements of 186Os/188Os and 187Os/188Os in 10 Os-rich platinum group element (PGE) alloys from placer deposits formed by the mechanical erosion of peridotite-bearing ophiolites in the Klamath and Siskiyou Mountains in northern California and southwestern Oregon. These data nearly double our database of high-precision 186Os/188Os measurements on such samples. Together with previously published data, our new results reinforce the conclusion that the radiogenic 186Os/188Os compositions of these PGE alloys are very difficult to reconcile with a derivation of their Os from the outer core. Such a model requires extremely early growth of the inner core to its present size, within several hundred million years after accretion of the Earth, which is geophysically implausible. Collectively, our data suggest instead that partial melting or metasomatic processes in the upper mantle play a primary role in controlling the Os isotopic systematics of these Os-rich PGE alloys and suggest the existence of upper mantle components characterized by radiogenic 186Os/188Os ratios. Pyroxene-rich lithologies are possible candidates.

  8. Platinum group elements and gold in ferromanganese crusts from Afanasiy-Nikitin seamount, equatorial Indian Ocean: Sources and fractionation

    USGS Publications Warehouse

    Banakar, V.K.; Hein, J.R.; Rajani, R.P.; Chodankar, A.R.

    2007-01-01

    The major element relationships in ferromanganese (Fe-Mn) crusts from Afanasiy-Nikitin seamount (ANS), eastern equatorial Indian Ocean, appear to be atypical. High positive correlations (r = 0.99) between Mn/Co and Fe/Co ratios, and lack of correlation of those ratios with Co, Ce, and Ce/Co, indicate that the ANS Fe-Mn crusts are distinct from Pacific seamount Fe-Mn crusts, and reflect region-specific chemical characteristics. The platinum group elements (PGE: Ir, Ru, Rh, Pt, and Pd) and Au in ANS Fe-Mn crusts are derived from seawater and are mainly of terrestrial origin, with a minor cosmogenic component. The Ru/Rh (0.5-2) and Pt/Ru ratios (7-28) are closely comparable to ratios in continental basalts, whereas Pd/Ir ratios exhibit values ( 0.75) correlations between water depth and Mn/Co, Fe/Co, Ce/Co, Co, and the PGEs. Fractionation of the PGE-Au from seawater during colloidal precipitation of the major-oxide phases is indicated by well-defined linear positive correlations (r > 0.8) of Co and Ce with Ir, Ru, Rh, and Pt; Au/Co with Mn/Co; and by weak or no correlations of Pd with water depth, Co-normalized major-element ratios, and with the other PGE (r < 0.5). The strong enrichment of Pt (up to 1 ppm) relative to the other PGE and its positive correlations with Ce and Co demonstrate a common link for the high concentrations of all three elements, which likely involves an oxidation reaction on the Mn-oxide and Fe-oxyhydroxide surfaces. The documented fractionation of PGE-Au and their positive association with redox sensitive Co and Ce may have applications in reconstructing past-ocean redox conditions and water masses.

  9. Platinum group element abundances in the upper continental crust revisited - New constraints from analyses of Chinese loess

    NASA Astrophysics Data System (ADS)

    Park, Jung-Woo; Hu, Zhaochu; Gao, Shan; Campbell, Ian H.; Gong, Hujun

    2012-09-01

    Platinum group element (PGE) abundances in the upper continental crust (UCC) are poorly constrained with published values varying by up to an order of magnitude. We evaluated the validity of using loess to estimate PGE abundances in the UCC by measuring these elements in seven Chinese loess samples using a precise method that combines NiS fire assay with isotope dilution. Major and trace elements of the Chinese loess show a typical upper crustal composition and PGE abundances are consistent with literature data on Chinese loess, except for Ru, which is a factor of 10 lowe than published values. We suggest that the high Ru data and RuN/IrN values of Chinese loess reported by Peucker-Ehrenbrink and Jahn (2001) (Geochem. Geophys. Geosys.2, 2001GC000172) are an analytical artifact, rather than a true geochemical characteristic of loess because likely sources of loess are not significantly enriched in Ru and transport and deposition processes cannot preferentially enrich Ru in loess. The effect of eolian fractionation on PGE abundances in loess appears to be limited because Chinese loess from different locations shows similar PGE patterns and concentrations. This conclusion is supported by strong positive correlations between the PGE (except for Pt) and other compatible elements such as Fe2O3, Ni, Cr, Co. Using a compilation of PGE data for loess from China, Argentina and Europe, including our data but excluding one sample with an anomalously high Pt content, we propose average PGE abundances for global loess of Ir = 0.022 ppb (ng/g), Ru = 0.030 ppb, Rh = 0.018 ppb, Pt = 0.599 ppb, and Pd = 0.526 ppb, and suggest that these are the best current estimates for the PGE abundances of the UCC.

  10. Bioaccumulation of platinum group elements and characterization of their species in Lolium multiflorum by size-exclusion chromatography coupled with ICP-MS.

    PubMed

    Lesniewska, Barbara A; Messerschmidt, Jürgen; Jakubowski, Norbert; Hulanicki, Adam

    2004-04-25

    The bioaccumulation of Pt, Pd and Rh by grass grown hydroponically with nutrient solutions containing these ions at elevated (38.7 mg l(-1) Pt, 21.7 mg l(-1) Pd and 7.1 mg l(-1) Rh) and medium (3.6 mg l(-1) Pt, 4.4 mg l(-1) Pd and 0.5 mg l(-1) Rh) concentrations was studied by using inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The highest bioaccumulation factors were obtained for Pd and Rh in roots and for Pt in leaves. The obtained results showed that most of the studied metals were accumulated in roots, and only a small fraction was really metabolised and transported to leaves. The multi-element capability of ICP-SFMS has been exploited to study the metabolism of platinum group elements (PGEs) in cultivated plants. The species of studied metals were extracted from roots and leaves and separated into two mass fractions by ultra-filtration. The low molecular mass (<10 kDa) fractions of the root and the leaf extracts were investigated by size-exclusion chromatography (SEC) coupled on-line to ICP-SFMS. The presence of Ca, Cu, S and C in the same fractions as Pt, Pd and Rh may indicate the interaction of PGEs with phytochelatins and carbohydrates. PMID:15081741

  11. Platinum-group elements in the Eastern Deccan volcanic province and a comparison with platinum metals of the western Deccan

    NASA Astrophysics Data System (ADS)

    Crocket, James; Paul, Dalim; Lala, Trisha

    2013-08-01

    This study is the first detailed investigation of the platinum-group elements (PGE) at the eastern margin of the Deccan volcanic province of India. One of the PGE, osmium, is not included largely because of analytical problems. The study is focused on mafic volcanics and dykes from four areas including Amarkantak, Umaria, Shahdol and Chirimiri. The first two localities represent two lava piles of about 170 and 400 m thickness respectively. In Umaria, 16 flows have been demarcated based on petrography and field studies. The Shahdol samples are basal lava formations overlying Gondwana sediments (Carboniferous) and the Chirimiri samples are dykes. In this study, the western Deccan province is defined as the Western Ghats plus Kutch. On average, the PGE are ~20% higher in Amarkantak than Umaria and the flows are ~13% higher in PGE than the dykes. A Zr vs. Pd scattergram found a strong positive correlation for these two elements except for one Umaria sample which indicated severe Pd loss. A comparison of west and east parts of the Deccan volcanic province using primitive mantle normalization showed that higher values prevailed in the western province suite in the Ni-Ir-Ru-Pt region. In contrast, eastern province values dominated in the Pd-Au-Cu region at the `Cu' end of the profiles. A strong dominance of Pd in the eastern Deccan was also of interest. A number of factors, for example, percentage partial melting of the source rock and the temperature and pressure of partial melting strongly influence the character of these profiles. The observed PGE profile characteristics probably result in part from a long distance of subsurface transport of Deccan magma from the western to eastern regions.

  12. The origin of halide melt phases in layered intrusions, and their significance to platinum-group element mobility

    NASA Astrophysics Data System (ADS)

    Hanley, J. J.

    2007-12-01

    Fluid and melt inclusions are preserved within pegmatite bodies and cumulus minerals within mafic-ultramafic layered intrusions that host economic concentrations of the platinum-group elements (e.g., Bushveld Complex, South Africa; Stillwater Complex, Montana). The inclusions indicate that the earliest volatile phase to have exsolved from the crystallizing intrusions was a relatively anhydrous carbonic fluid (CO2-dominated). As crystallization proceeded, volatiles became increasingly water-rich and saline, consistent with the relative saturation limits of carbonic and aqueous fluids in mafic silicate liquids, and the partitioning behavior of Cl in fluid-melt systems. Previously unreported, the latest stage volatiles in the layered intrusions were halide melts (slightly hydrous molten salts) of relatively simply composition (NaCl with minor KCl or CaCl2) with salinities in excess of 90 wt% eq. NaCl or CaCl2. These volatiles were trapped at minimum temperatures of 760-800°C, near the eutectic temperature for water-saturated granitic liquid at moderate crustal pressures. Trace element analysis of the salt melt inclusions by laser ablation ICP-MS (ETH Zürich) show that they contain no detectable concentrations of ore and accessory metals. This is in contrast to the earlier, lower salinity volatiles which contain ppm-concentrations of Pt, Pd, As, Bi, Sb as well as abundant S and base metals. Heterogeneous entrapment of late-stage silicate melt and halide melt provides unambiguous evidence for the coexistence of both phases. However, experimental constraints on the nature of exsolved volatiles from mafic or felsic silicate liquids suggest that the halide melt phases cannot represent an exsolved phase from that coexisting silicate liquid, since this would require unrealistically high (initial) Cl:H2O ratios for the parental silicate liquid (> 9 for a granitic residue). Analysis of rhyodacitic silicate melt inclusions that coexist with the halide melt inclusions show

  13. Re-Os isotope and platinum group elements of a FOcal ZOne mantle source, Louisville Seamounts Chain, Pacific ocean

    NASA Astrophysics Data System (ADS)

    Tejada, Maria Luisa G.; Hanyu, Takeshi; Ishikawa, Akira; Senda, Ryoko; Suzuki, Katsuhiko; Fitton, Godfrey; Williams, Rebecca

    2015-02-01

    The Louisville Seamount Chain (LSC) is, besides the Hawaiian-Emperor Chain, one of the longest-lived hotspot traces. We report here the first Re-Os isotope and platinum group element (PGE) data for Canopus, Rigil, and Burton Guyots along the chain, which were drilled during IODP Expedition 330. The LSC basalts possess (187Os/188Os)i = 0.1245-0.1314 that are remarkably homogeneous and do not vary with age. A Re-Os isochron age of 64.9 ± 3.2 Ma was obtained for Burton seamount (the youngest of the three seamounts drilled), consistent with 40Ar-39Ar data. Isochron-derived initial 187Os/188Os ratio of 0.1272 ± 0.0008, together with data for olivines (0.1271-0.1275), are within the estimated primitive mantle values. This (187Os/188Os)i range is similar to those of Rarotonga (0.124-0.139) and Samoan shield (0.1276-0.1313) basalts and lower than those of Cook-Austral (0.136-0.155) and Hawaiian shield (0.1283-0.1578) basalts, suggesting little or no recycled component in the LSC mantle source. The PGE data of LSC basalts are distinct from those of oceanic lower crust. Variation in PGE patterns can be largely explained by different low degrees of melting under sulfide-saturated conditions of the same relatively fertile mantle source, consistent with their primitive mantle-like Os and primordial Ne isotope signatures. The PGE patterns and the low 187Os/188Os composition of LSC basalts contrast with those of Ontong Java Plateau (OJP) tholeiites. We conclude that the Re-Os isotope and PGE composition of LSC basalts reflect a relatively pure deep-sourced common mantle sampled by some ocean island basalts but is not discernible in the composition of OJP tholeiites.

  14. Anthropogenic platinum group element (Pt, Pd, Rh) concentrations in PM10 and PM2.5 from Kolkata, India.

    PubMed

    Diong, Huey Ting; Das, Reshmi; Khezri, Bahareh; Srivastava, Bijayen; Wang, Xianfeng; Sikdar, Pradip K; Webster, Richard D

    2016-01-01

    This study investigates platinum group elements (PGEs) in the breathable (PM10) and respirable (PM2.5) fractions of air particulates from a heavily polluted Indian metro city. The samples were collected from traffic junctions at the heart of the city and industrial sites in the suburbs during winter and monsoon seasons of 2013-2014. PGE concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The PGE concentrations in the samples from traffic junctions are within the range of 2.7-111 ng/m(3) for Pd, 0.86-12.3 ng/m(3) for Pt and 0.09-3.13 ng/m(3) for Rh, and from industrial sites are within the range of 3.12-32.3 ng/m(3) for Pd, 0.73-7.39 ng/m(3) for Pt and 0.1-0.69 ng/m(3) for Rh. Pt concentrations were lower in the monsoon compared to winter while Pd concentrations increased during monsoon and Rh stayed relatively unaffected across seasons. For all seasons and locations, concentrations of Pd > Pt > Rh, indicating dominance of Pd-containing exhaust converters. Most of the PGEs were concentrated in the PM2.5 fraction. A strong correlation (R ≥ 0.62) between the PGEs from traffic junction indicates a common emission source viz. catalytic converters, whereas a moderate to weak correlation (R ≤ 0.5) from the industrial sites indicate mixing of different sources like coal, raw materials used in the factories and automobile. A wider range of Pt/Pd, Pt/Rh and Pd/Rh ratios measured in the traffic junction possibly hint towards varying proportions of PGEs used for catalyst productions in numerous rising and established car brands. PMID:27536525

  15. Thermodynamic calculations of the volatility of the platinum group elements (PGE): The PGE content of fluids at magmatic temperatures

    NASA Astrophysics Data System (ADS)

    Wood, Scott A.

    1987-11-01

    The volatilities of the platinum-group elements as metals, oxides and chlorides were calculated at temperatures of 800-1600 K. Only Pd is significantly volatile as the metal. At log fH2O = 1 Kbar and 1200 K., the concentration (weight) of Pd in the vapor reaches 1 ppt and at 1600 K attains several ppb. The PGE oxides are extremely volatile at atmospheric oxygen fugacities. However, only Os and Ru have significant volatilities (≥ ppt) as oxides (OsO 4, RuO 3) at oxygen fugacities typical of magmatic PGE deposits (near QFM) and only at temperatures greater than 1400 K. Data on the volatility of PGE chlorides exist only for Pd and Ru, both of which are somewhat more volatile as chlorides than as oxides. At 1400 log fH2O = 1 bars, fHCl = 100 bars and at QFM, the calculated vapor concentrations of PdCl 2 and RuCl 3 are 500 ppt and 20 ppt, respectively (and less in the presence of sulfur). However, higher concentrations of PGE may be attained at higher temperatures, higher fO2, higher fHCl or lower fH2. Also, any interactions between water vapor and PGE vapor species (e.g. ionization, solvation) would tend to increase the vapor concentration of PGE. Volatility of Ir as IrF 6 is insignificant at all conditions. Vapor transport of the more volatile PGE as chlorides may play some role in the transport of these metals in mafic igneous complexes such as the Stillwater or the Bushveld. However, under the conditions where the PGE are most volatile, the metals Fe, Ni and Cu are several factors often more volatile, so that enrichment of the PGE and Cu over Ni and Fe cannot be explained by chloride transport alone.

  16. Platinum Group Elements (PGE) geochemistry of komatiites and boninites from Dharwar Craton, India: Implications for mantle melting processes

    NASA Astrophysics Data System (ADS)

    Saha, Abhishek; Manikyamba, C.; Santosh, M.; Ganguly, Sohini; Khelen, Arubam C.; Subramanyam, K. S. V.

    2015-06-01

    High MgO volcanic rocks having elevated concentrations of Ni and Cr are potential hosts for platinum group elements (PGE) owing to their primitive mantle origin and eruption at high temperatures. Though their higher PGE abundance is economically significant in mineral exploration studies, their lower concentrations are also valuable geochemical tools to evaluate petrogenetic processes. In this paper an attempt has been made to evaluate the PGE geochemistry of high MgO volcanic rocks from two greenstone belts of western and eastern Dharwar Craton and to discuss different mantle processes operative at diverse geodynamic settings during the Neoarchean time. The Bababudan greenstone belt of western and Gadwal greenstone belt of eastern Dharwar Cratons are dominantly composed of high MgO volcanic rocks which, based on distinct geochemical characteristics, have been identified as komatiites and boninites respectively. The Bababudan komatiites are essentially composed of olivine and clinopyroxene with rare plagioclase tending towards komatiitic basalts. The Gadwal boninites contain clinopyroxene, recrystallized hornblende with minor orthopyroxene, plagioclase and sulphide minerals. The Bababudan komatiites are Al-undepleted type (Al2O3/TiO2 = 23-59) with distinctly high MgO (27.4-35.8 wt.%), Ni (509-1066 ppm) and Cr (136-3036 ppm) contents. These rocks have low ΣPGE (9-42 ppb) contents with 0.2-2.4 ppb Iridium (Ir), 0.2-1.4 ppb Osmium (Os) and 0.4-4.4 ppb Ruthenium (Ru) among Iridium group PGE (IPGE); and 1.4-16.2 ppb Platinum (Pt), 2.8-19 ppb Palladium (Pd) and 0.2-9.8 ppb Rhodium (Rh) among Platinum group PGE (PPGE). The Gadwal boninites are high-Ca boninites with CaO/Al2O3 ratios varying between 0.8 and 1.0, with 12-24 wt.% MgO, 821-1168 ppm Ni and 2307-2765 ppm Cr. They show higher concentration of total PGE (82-207 ppb) with Pt concentration ranging from 13 to 19 ppb, Pd between 65 and 180 ppb and Rh in the range of 1.4-3 ppb compared to the Bababudan komatiites. Ir

  17. Platinum group and chalcophile element systematics of serpentinized peridotites from the St. Elena ophiolite in Costa Rica

    NASA Astrophysics Data System (ADS)

    Holm, J.; Bizimis, M.; Schwarzenbach, E. M.; Foustoukos, D.; Frisby, C. P.; Brandon, A. D.; Gazel, E.

    2015-12-01

    We present in situ LA-ICPMS data on platinum group element (PGE) and chalcophile element (namely Cu, Ag, Te, Au, Pb) systematics in sulfides from partially serpentinized peridotites of the St. Elena ophiolite, Costa Rica. PGE are strong indicators of primary mantle processes, though their behavior during low temperature alteration processes such as serpentinization is not well understood. St. Elena sulfides are dominantly pentlandites that coexist with Fe-Ni alloys and native Cu. This indicates extremely low fO2 and fS2 conditions likely established during the early stages of serpentinization. We observe extremely variable PGE-Re concentrations in the sulfides, (e.g. [Os] = 2 - 100,000 times primitive mantle, PM). Low [Os] sulfides have high Pd/Os, which in turn correlates positively with Cu concentrations, suggesting Pd enrichment through Cu-rich fluids (e.g. Schwarzenbach et al., 2014, CMP) as opposed to melt-rock reaction. Sulfide PM-normalized PGE-Re patterns are dominated by strong Pt depletions (e.g., Pt/Pd = 0.80-0.0009). Occasional Pt enrichments over Pd and Ru (or Rh) in a PM-normalized pattern (~5% of the sulfide population) often correlate with Te and/or Au enrichments. Pt enrichment was also observed in a composite pentlandite-awaruite, suggesting possible exsolution of Pt from sulfides under extremely low fS2 conditions. Pb concentrations do not correlate with other chalcophiles or PGE. Pb ranges from 0.01-31.64 ppm with the majority of sulfides <5 ppm, and an average concentration of 2.77 ppm (n=64). Assuming that this Pb concentration is representative of mantle sulfides, this implies that Pb is not dominantly held in sulfides in the upper mantle. Combination of in situ and bulk rock PGE analyses will be used to distinguish the effects of primary magmatic signatures (e.g., melt depletion, melt-rock interaction) and secondary processes such as serpentinization on the PGE-Re and chalcophile element systematics of these sulfides.

  18. Platinum-group element concentrations in pyrite from the Main Sulfide Zone of the Great Dyke of Zimbabwe

    NASA Astrophysics Data System (ADS)

    Piña, R.; Gervilla, F.; Barnes, S.-J.; Oberthür, T.; Lunar, R.

    2016-02-01

    The Main Sulfide Zone (MSZ) of the Great Dyke of Zimbabwe hosts the world's second largest resource of platinum-group elements (PGE) after the Bushveld Complex in South Africa. The sulfide assemblage of the MSZ comprises pyrrhotite, pentlandite, chalcopyrite, and minor pyrite. Recently, several studies have observed in a number of Ni-Cu-PGE ore deposits that pyrite may host significant amounts of PGE, particularly Pt and Rh. In this study, we have determined PGE and other trace element contents in pyrite from the Hartley, Ngezi, Unki, and Mimosa mines of the Great Dyke by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Based on the textures and PGE contents, two types of pyrite can be differentiated. Py1 occurs as individual euhedral or subhedral grains or clusters of crystals mostly within chalcopyrite and pentlandite, in some cases in the form of symplectitic intergrowths, and is PGE rich (up to 99 ppm Pt and 61 ppm Rh; 1.7 to 47.1 ppm Ru, 0.1 to 7.8 ppm Os, and 1.2 to 20.2 ppm Ir). Py2 occurs as small individual euhedral or subhedral crystals within pyrrhotite, pentlandite, and less frequently within chalcopyrite and silicates and has low PGE contents (<0.11 ppm Pt, <0.34 ppm Rh, <2.5 ppm Ru, <0.37 ppm Ir, and <0.40 ppm Os). Py1 contains higher Os, Ir, Ru, Rh, and Pt contents than the associated pyrrhotite, pentlandite, and chalcopyrite, whereas Py2 has similar PGE contents as coexisting pyrrhotite and pentlandite. Based on the textural relationships, two different origins are attributed for each pyrite type. Py1 intergrowth with pentlandite and chalcopyrite is inferred to have formed by late, low temperature (<300 °C) decomposition of residual Ni-rich monosulfide solid solution, whereas Py2 is suggested to have formed by replacement of pyrrhotite and pentlandite caused by late magmatic/hydrothermal fluids.

  19. Biological role in the transformation of platinum-group mineral grains

    NASA Astrophysics Data System (ADS)

    Reith, Frank; Zammit, Carla M.; Shar, Sahar S.; Etschmann, Barbara; Bottrill, Ralph; Southam, Gordon; Ta, Christine; Kilburn, Matthew; Oberthür, Thomas; Ball, Andrew S.; Brugger, Joël

    2016-04-01

    Platinum-group elements are strategically important metals. Finding new deposits is becoming increasingly difficult owing to our limited understanding of the processes that affect their mobility in surface environments. Microorganisms have been shown to promote the mobility of metals around ore deposits. Here we show that microorganisms influence the mobility of platinum-group elements in mineral grains collected from Brazil, Australia and Colombia. Scanning electron microscopy showed biofilms covering the platinum-group mineral grains. The biofilms contained abundant platinum-group element nanoparticles and microcrystalline aggregates, and were dominated by Proteobacteria, many of which were closely related to known metal-resistant species. Some platinum-group mineral grains contained carbon, nitrogen, sulfur, selenium and iodine, suggesting the grains may be biogenic in origin. Molecular analyses show that Brazilian platinum-palladium grains hosted specific bacterial communities, which were different in composition from communities associated with gold grains, or communities in surrounding soils and sediments. Nano-phase metallic platinum accumulated when a metallophillic bacterium was incubated with a percolating platinum-containing medium, suggesting that biofilms can cause the precipitation of mobile platinum complexes. We conclude that biofilms are capable of forming or transforming platinum-group mineral grains, and may play an important role for platinum-group element dispersion and re-concentration in surface environments.

  20. Ni, Cu, Au, and platinum-group element contents of sulphides associated with intraplate magmatism: A synthesis

    USGS Publications Warehouse

    Barnes, S.-J.; Zientek, M.L.; Severson, M.J.

    1997-01-01

    The tectonic setting of intraplate magmas, typically a plume intersecting a rift, is ideal for the development of Ni - Cu - platinum-group element-bearing sulphides. The plume transports metal-rich magmas close to the mantle - crust boundary. The interaction of the rift and plume permits rapid transport of the magma into the crust, thus ensuring that no sulphides are lost from the magma en route to the crust. The rift may contain sediments which could provide the sulphur necessary to bring about sulphide saturation in the magmas. The plume provides large volumes of mafic magma; thus any sulphides that form can collect metals from a large volume of magma and consequently the sulphides will be metal rich. The large volume of magma provides sufficient heat to release large quantities of S from the crust, thus providing sufficient S to form a large sulphide deposit. The composition of the sulphides varies on a number of scales: (i) there is a variation between geographic areas, in which sulphides from the Noril'sk - Talnakh area are the richest in metals and those from the Muskox intrusion are poorest in metals; (ii) there is a variation between textural types of sulphides, in which disseminated sulphides are generally richer in metals than the associated massive and matrix sulphides; and (iii) the massive and matrix sulphides show a much wider range of compositions than the disseminated sulphides, and on the basis of their Ni/Cu ratio the massive and matrix sulphides can be divided into Cu rich and Fe rich. The Cu-rich sulphides are also enriched in Pt, Pd, and Au; in contrast, the Fe-rich sulphides are enriched in Fe, Os, Ir, Ru, and Rh. Nickel concentrations are similar in both. Differences in the composition between the sulphides from different areas may be attributed to a combination of differences in composition of the silicate magma from which the sulphides segregated and differences in the ratio of silicate to sulphide liquid (R factors). The higher metal

  1. Positive anomaly in platinum group elements and the presence of shocked diamonds: Two question marks at the Younger Dryas

    NASA Astrophysics Data System (ADS)

    Claeys, P. F.; Schryvers, D.; Tian, H.; Goderis, S.

    2009-12-01

    Recently, a large size impact was proposed as the cause of the global changes taking place at the Younger Dryas (YD) some 12,9 kyr ago. Impact evidence was reported in a C-rich black layer of broad geographic distribution. The impact markers consist of a large anomaly in the concentration of platinum group elements (PGE) and the presence of nanodiamonds, in particular lonsdaleite, which hexagonal structure is believed to be of shock origin. The impact is proposed to have occurred on the North American continent. A crater large enough (> 150 km) to induce a mass extinction some ~12.9 ka ago, formed in a geologically well-known area, is unlikely to have escaped detection. Therefore, an alternative hypothesis is that a cometary projectile exploded fully within the atmosphere spreading PGE and shock formed diamonds, without any target rock contribution, all around the Northern hemisphere. So far, PGE measurements failed to reproduce the elevated (> ppb) concentrations reported previously at Younger Dryas sites containing the black layer. In Lommel (Belgium) where the first study detected up to 117 ppb Ir, the Ir concentration is below the detection limit of the method (NiS fire assay + ICP-MS) used (0.06 ppb). At all sites analyzed the PGE pattern is typical of that of the continental crust. In several craters (Popigai, Ries) or at the KT boundary nanodiamonds have been reported associated with shocked materials. Several types of carbon components occur in the black layer of the Lommel section such as i) flakes reaching up to 1 µm, ii) nano particles of cubic diamond, 1 to 10 nm in size and iii) larger carbon onion-ring structures, which core can act as a nanoscopic pressure cell leading to the formation of nanodiamond by self- compression. The Lommel nanodiamonds present in the Younger Dryas layer do resemble nanodiamonds found in carbon spherules of unknown origin previously reported in top soil from several localities in Belgium and Germany. The C stable isotopic

  2. Do The Concentrations Of Platinum Group Elements In The Younger Dryas Black Layer Really Support An Extraterrestrial Origin?

    NASA Astrophysics Data System (ADS)

    Claeys, P.; Paquay, F.; Goderis, S.; Vanhaecke, F.

    2008-12-01

    An enigmatic carbon-rich black layer, of possible worldwide occurrence, is interpreted to indicate an extraterrestrial impact around 12.9 ka, a period coeval with the Younger Dryas (YD) environmental changes (Firestone et al. 2007, PNAS 104). This interpretation is based on the possible identification of a series of markers postulated to be of impact origin, such as magnetic grains and microspherules, charcoal, soot, C- spherules, nanodiamonds, fullerenes with extraterrestrial He and elevated concentrations of Ir. Among these markers, only the elevated Ir concentration is a non-ambiguous impact indicator. In early 2007, one of us (PC) measured the concentration of platinum group elements (including Ir) in 4 samples of this black layer. Allen West provided the samples along with their Ir concentrations. The samples originated from Howard Bay, NC (level HB-11D2) and Blackwater Draw, NM (levels BW-DT, D/C and BW-B/A), and were supposed to contain 15 ng/g Ir (<150 micron magnetic fraction), 2.0 ng/g Ir (bulk sediment), 2.25 ng/g Ir (bulk sediment) and <0.1 ng/g Ir (bulk sediment) respectively. In Table 1 of Firestone et al. (2007) the Blackwater Draw sample contains 2.3 ng/g Ir, and the separated magnetic fraction rises up 24 ng/g. The obtained results showed that none of the 4 samples yielded PGE concentrations above 0.5 ng/g. Considering the attention the claim of a possible YD impact has generated in the last year, we are currently reanalyzing these 4 samples of the black layer using high precision NiS fire-assay preconcentration combined with ICP-MS analyses. On proven crater melt rocks or impact layers, the quantitation limits reach: 0.06 ng/g Ru, 0.01 ng/g Rh, 0.14 ng/g Pd, 0.06 ng/g Ir, and 0.1 ng/g Pt, far below the Ir values claimed by Firestone et al. (2007). In addition, these 4 samples are being analyzed for Os isotopes, known to be most sensitive for the detection of minute amounts of extraterrestrial components (%<%%<%0.05 wt%) in impact layers. The

  3. Platinum-group element abundance and distribution in chromite deposits of the Acoje Block, Zambales Ophiolite Complex, Philippines

    USGS Publications Warehouse

    Bacuta, G.C., Jr.; Kay, R.W.; Gibbs, A.K.; Lipin, B.R.

    1990-01-01

    Platinum-group elements (PGE) occur in ore-grade concentration in some of the chromite deposits related to the ultramafic section of the Acoje Block of the Zambales Ophiolite Complex. The deposits are of three types: Type 1 - associated with cumulate peridotites at the base of the crust; Type 2 - in dunite pods from the top 1 km of mantle harzburgite; and Type 3 - like Type 2, but in deeper levels of the harzburgite. Most of the deposites have chromite compositions that are high in Cr with Cr/(Cr + Al) (expressed as chromium index, Cr#) > 0.6; high-Al (Cr# Pd, thought to be characteristic of PGE-barren deposits) and positive slope (Ir < Pd, characteristic of PGE-rich deposits). Iridium, Ru and Os commonly occur as micron-size laurite (sulfide) inclusions in unfractured chromite. Laurite and native Os are also found as inclusions in interstitial sulfides. Platinum and Pd occur as alloy inclusions (and possibly as solid solution) in interstitial Ni-Cu sulfides and as tellurobismuthides in serpentine and altered sulfides. Variability of PGE distribution may be explained by alteration, crystal fractionation or partial melting processes. Alteration and metamorphism were ruled out, because PGE contents do not correlate with degree of serpentinization or the abundance and type (hydroxyl versus non-hydroxyl) of silicate inclusions in chromite. Preliminary Os isotopic data do not support crustal contamination as a source of the PGEs in the Acoje deposits. The anomalous PGE concentrations in Type 1 high-Cr chromite deposits are attributed to two stages of enrichment: an early enrichment of their mantle source from previous melting events and a later stage of sulfide segregation accompanying chromite crystallization. High-Al chromite deposits which crystallized from basalts derived from relatively low degrees of melting owe their low PGE content to partitioning of PGEs in sulfides and alloys that remain in the mantle. High-Cr deposits crystallized from melts that were

  4. Platinum-Group Element Variations in Hawaiian Lavas: Constraints on the Role of Sulfides during Melt Generation and Fractional Crystallization

    NASA Astrophysics Data System (ADS)

    Lassiter, J. C.

    2003-12-01

    Platinum-group elements (PGE) are highly compatible in mantle and magmatic sulfides, with sulfide melt/silicate melt partition coefficients typically on the order of 104 or higher. PGE abundances in basaltic melts are therefore very sensitive to the presence or absence of residual sulfides during melt generation and the fractionation of magmatic sulfides during crystallization. PGE abundances (Ir, Os, Ru, Pt, Pd) were measured in lavas from Mauna Kea and Koolau volcanoes, Hawaiian Islands to constrain the abundance of residual sulfide in the Hawaiian plume during melt generation as well as the role of sulfide fractionation during melt evolution. Iridium, Os, and Ru are positively correlated with MgO content in lavas ranging from ˜6-28 wt.% MgO. Bulk partition coefficients during fractional crystallization range from ˜4 (Ir) to ˜7 (Os). The compatible behavior of Ir, Os and Ru in Hawaiian melts likely reflects the high compatibility of these elements in Cr-spinel, which coprecipitates with olivine in most Hawaiian lavas. In contrast, no significant trend is observed in Pt or Pd abundances with MgO content, indicating bulk partition coefficients for these elements of ˜1. Pt and Pd are predicted to be incompatible in Cr-spinels, but are highly compatible in magmatic sulfides (Dsulfide/silicate = 4.5x104) . The low bulk partition coefficients for Pt and Pd in the Koolau and Mauna Kea lavas indicate that sulfide segregation was insignificant during fractional crystallization, even in lavas that have experienced up to 25% olivine fractionation. Lack of sulfide saturation/segregation could reflect sulfur degassing in shallow magma chambers. However, deep submarine lavas from the HSDP-2 Mauna Kea drillcore display similar PGE trends. Therefore, it is likely that primary Hawaiian magmas (with ˜15-16 wt.% MgO) are at least ˜20-25% sulfur undersaturated when they reach crustal levels. If the source of Hawaiian lavas contains residual sulfide, primary Hawaiian melts

  5. Ancient mantle trapped in the Mariana arc-basin system: Insights from the platinum group elements and Os isotopes

    NASA Astrophysics Data System (ADS)

    Savov, I. P.; Shirey, S. B.; Horan, M. F.; Mock, T. D.

    2006-12-01

    Serpentinized harzburgites recently drilled during ODP Leg 195 at South Chamorro Seamount in the Mariana forearc region have been studied for their platinum group element (PGE) concentrations and Os isotopic compositions. The samples allow a look at the slab fluid-modified subarc mantle immediately overlaying the actively subducting Pacific slab at depths of ~ 30 km. The average PGE (Os 2.3 ppb, Ir 1.5 ppb, Ru 5.4 ppb, Pd 1.6 ppb and Pt 16.3 ppb) and Re (60 ppt) abundances are comparable to those measured in other subarc mantle xenolith suites. The PGE and Re abundances are depleted up to 3 orders of magnitude relative to chondrites, with relative order of depletions Ru > Os > Ir> Pt> Re> Pd. The variable Pd contents (0.01-4.5 ppb) and the low Pd/Os (<2) in the Mariana forearc samples differ significantly from that of altered oceanic crust (Pd/Os~ 22), suggesting Os remained relatively unchanged during low temperature subduction-fluid additions. Serpentinitization of the harzburgites occurred in equilibrium with fluids that were both reducing and highly alkaline. Os in its original phases may be stabilized in such an environment, therefore can preserve evidence for ancient melting despite later slab interactions. Finally, the high Pt/Pd (ave. ~ 25) and low Re contents (ave.~ 60 ppt) in the Leg 195 forearc samples are complementary to those measured in boninites from the Izu-Bonin-Mariana arc-basin system, showing a genetic relationship. Our samples reveal an average 187Os/188Os of 0.123 [range = 0.119- 0.127], making them similar to abyssal peridotites from elsewhere. Radiogenic 187Os/188Os ratios would have been imparted to the serpentinites by slab fluids, so the subchondritic Os isotopic compositions implies that peridotite-slab fluid interactions did not alter the Os isotope systematics of the mantle protoliths. Low alumina abundances (<1 %) and trace element signatures (low HFSE; REE with U-shaped chondrite-normalized patterns and 2-3 times lower than

  6. Sniffing for Clues to the Dinosaurs Demise: Measurement of Osmium Isotope Compositions and Platinum Group Element Abundances in Volcanic Emissions

    NASA Astrophysics Data System (ADS)

    Sims, K. W.; Peucker-Ehrenbrink, B.; Mather, T.; Pyle, D.; Martin, R.; Gauthier, P.; Aiuppa, A.

    2005-12-01

    Platinum Group Elements (PGE: Os, Ir, Rh, Ru, Pt, Pd) and osmium isotopes measured in marine and terrestrial sediment, snow and ice records are important paleo-tracers of riverine, hydrothermal, extraterrestrial, volcanic and anthropogenic inputs into the global surficial environment. For instance, the marine Os isotope record across the Cretaceous-Tertiary Boundary (KTB) indicates that the onset of the main phase of Deccan volcanism and the transient late Maastrichtian warming preceded the large extraterrestrial impact and the related KTB mass extinction by several hundred thousand years [Ravizza and Peucker-Ehrenbrink, 2003]. Distinguishing extraterrestrial from volcanic PGE sources has been difficult due to the similarity in Os isotopic compositions, complex PGE fractionations, and our lack of knowledge of the Os isotopic composition and PGE abundances in volcanic aerosols. These difficulties have fueled vigorous debate about extraterrestrial vs. volcanic triggers of mass extinctions in the geologic record. To assess the volcanic contribution to the global Re-Os-PGE cycle we have initiated a study of Os isotopic compositions and PGE abundances in volcanic emissions from volcanoes around the globe. Here we report preliminary data on PGE abundances and Os isotopes measured in gas and aerosol filter samples from Vulcan Masaya, Nicaragua and Mt Etna, Italy. Samples were analyzed by ID-ICPMS (ThermoFinnigan ELEMENT 2 and NEPTUNE) at the Woods Hole Oceanographic Institution. Osmium isotope compositions of the filters are unradiogenic (0.1272 to 0.187). Osmium concentrations range from 28 to 97 pg/cubic meter and are 3-4 orders of magnitude lower than those measured by Krahenbuhl et al. [1992] during the spring 1984 eruption of Mauna Loa just after the lava fountaining phase. Normalized PGE abundance patterns are fractionated relative to carbonaceous chondrites and two important features distinguish the pattern from other important PGE sources: 1) Os/Ir is much higher

  7. Optimization of determination of platinum group elements in airborne particulate matter by inductively coupled plasma mass spectrometry.

    PubMed

    Bujdoš, Marek; Hagarová, Ingrid; Matúš, Peter; Canecká, Lucia; Kubová, Jana

    2012-03-01

    Determination of automotive traffic-emitted platinum group metals (PGM) by inductively coupled plasma quadrupole mass spectrometry (ICP-MS) was optimized. The interferences from Sr, Cu, Pb, Y, Cd, Zr and Hf were evaluated using model solutions. Plasma radiofrequency (RF) power and nebulizer gas flow were optimized for 103Rh, 105Pd, 108Pd and 195Pt. Two standard reference materials were analyzed: SARM-7 Platinum ore and BCR-723 Road dust. The optimized procedure was used to analyze samples of airborne particulate matter collected in the urban site with heavy automotive traffic in the centre of Bratislava, Slovakia. PMID:24061181

  8. PLATINUM-GROUP METALS

    EPA Science Inventory

    The document assembles, organizes, and evaluates all pertinent information (up to April 1976) about the effects on man and his environment that result either directly or indirectly from pollution by platinum-group metals: iridium (Ir), osmium (Os), palladium (Pd), platinum (Pt), ...

  9. Evidence from meimechites and other low-degree mantle melts for redox controls on mantle-crust fractionation of platinum-group elements

    PubMed Central

    Mungall, James E.; Hanley, Jacob J.; Arndt, Nicholas T.; Debecdelievre, Anne

    2006-01-01

    Understanding of the geochemistry of the chalcophile elements [i.e., Os, Ir, Ru, Pt, Pd (platinum-group elements), and Au, Cu, Ni] has been informed for at least 20 years by the common assumption that when crust-forming partial melts are extracted from the upper mantle, sulfide liquid in the restite sequesters chalcophile elements until the extent of partial melting exceeds ≈25% and all of the sulfide has been dissolved in silicate melt [Hamlyn, P. R. & Keays, R. R. (1985) Geochim. Cosmochim. Acta 49, 1797–1811]. Here we document very high, unfractionated, chalcophile element concentrations in small-degree partial melts from the mantle that cannot be reconciled with the canonical residual sulfide assumption. We show that the observed high, unfractionated platinum-group element concentrations in small-degree partial melts can be attained if the melting takes place at moderately high oxygen fugacity, which will reduce the amount of sulfide due to the formation of sulfate and will also destabilize residual monosulfide solid solution by driving sulfide melts into the spinel-liquid divariant field. Magmas formed at high oxygen fugacity by small degrees of mantle melting can be important agents for the transfer of chalcophile elements from the upper mantle to the crust and may be progenitors of significant ore deposits of Pt, Pd, and Au. PMID:16908861

  10. Partitioning of platinum-group elements and Au between sulfide liquid and basalt and the origins of mantle-crust fractionation of the chalcophile elements

    NASA Astrophysics Data System (ADS)

    Mungall, James E.; Brenan, James M.

    2014-01-01

    The partitioning of platinum-group elements (PGE; Os, Ir, Ru, Rh, Pt, and Pd) and Au between sulfide melt and silicate melt (i.e., DPGEsul) exerts a critical control on the PGE composition of the Earth’s crust and mantle, but previous estimates have been plagued by experimental uncertainties and vary through several orders of magnitude. Here we present direct experimental measurements of DPGEsul, based on in situ microanalysis of the sulfide and silicate melt, with values ranging from ∼4 × 105 (Ru) to ∼2-3 × 106 (Ir, Pt). Our measurements of DPGEsul are >100 times larger than previous results but smaller than anticipated based on comparison of alloy solubilities in sulfide melts and S-free silicate melts. The presence of S in the silicate melt greatly increases alloy solubility. We use our new set of partition coefficients to develop a fully constrained model of PGE behavior during melting which accurately predicts the abundances of PGE in mantle-derived magmas and their restites, including mid-ocean ridge basalts, continental picrites, and the parental magmas of the Bushveld Complex of South Africa. Our model constrains mid-ocean ridge basalt (MORB) to be the products of pooled low and high degree fractional melts. Within-plate picrites are pooled products of larger degrees of fractional melting in columnar melting regimes. A significant control on PGE fractionation in mantle-derived magmas is exerted by residual alloy or platinum group minerals in their source. At low pressures (e.g., MORB genesis) the mantle residual to partial melting retains primitive mantle inter-element ratios and abundances of PGE until sulfide has been completely dissolved but then evolves to extremely high Pt/Pd and low Pd/Ir because Pt and Ir alloys form in the restite. During melting at high pressure to form picrites or komatiites Ir alloy appears as a restite phase but Pt alloy is not stable due to the large effect of pressure on fS2, and of temperature on fO2 along an internal

  11. Rhenium-osmium isotope and platinum-group elements in the Xinjie layered intrusion, SW China: Implications for source mantle composition, mantle evolution, PGE fractionation and mineralization

    NASA Astrophysics Data System (ADS)

    Zhong, Hong; Qi, Liang; Hu, Rui-Zhong; Zhou, Mei-Fu; Gou, Ti-Zhong; Zhu, Wei-Guang; Liu, Bing-Guang; Chu, Zhu-Yin

    2011-03-01

    The Xinjie mafic-ultramafic layered intrusion in the Emeishan large igneous province (ELIP) hosts Cu-Ni-platinum group element (PGE) sulfide ore layers within the lower part and Fe-Ti-V oxide-bearing horizons within the middle part. The major magmatic Cu-Ni-PGE sulfide ores and spatially associated cumulate rocks are examined for their PGE contents and Re-Os isotopic systematics. The samples yielded a Re-Os isochron with an age of 262 ± 27 Ma and an initial 187Os/ 188Os of 0.12460 ± 0.00011 ( γOs( t) = -0.5 ± 0.1). The age is in good agreement with the previously reported U-Pb zircon age, indicating that the Re-Os system remained closed for most samples since the intrusion emplacement. They have near-chondritic γOs( t) values ranging from -0.7 to -0.2, similar to those of the Lijiang picrites and Song Da komatiites. Exceptionally, two samples from the roof zone and one from upper sequence exhibit radiogenic γOs( t) values (+0.6 to +8.6), showing minor contamination by the overlying Emeishan basalts. The PGE-rich ores contain relatively high PGE and small amounts of sulfides (generally less than 2%) and the abundance of Cu and PGE correlate well with S, implying that the distribution of these elements is controlled by the segregation and accumulation of a sulfide liquid. Some ore samples are poor in S (mostly <800 ppm), which may due to late-stage S loss caused by the dissolution of FeS from pre-existing sulfides through their interaction with sulfide-unsaturated flowing magma. The combined study shows that the Xinjie intrusion may be derived from ferropicritic magmas. The sharp reversals in Mg#, Cr/FeO T and Cr/TiO 2 ratios immediately below Units 2-4, together with high Cu/Zr ratios decreasing from each PGE ore layer within these cyclic units, are consistent with multiple magma replenishment episodes. The sulfides in the cumulate rocks show little evidence of PGE depletion with height and thus appear to have segregated from successive inputs of fertile magma

  12. Platinum-group element distribution in base-metal sulfides of the UG2 chromitite, Bushveld Complex, South Africa—a reconnaissance study

    NASA Astrophysics Data System (ADS)

    Osbahr, Inga; Oberthür, Thomas; Klemd, Reiner; Josties, Anja

    2014-08-01

    Two drill cores of the UG2 chromitite from the eastern and western Bushveld Complex were studied by whole-rock analysis, ore microscopy, SEM/Mineral Liberation Analysis (MLA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. The top and base of the UG2 main seam have the highest bulk-rock Pd and Pt concentrations. Sulfides mostly occur as aggregates of pentlandite, chalcopyrite, and rare pyrrhotite and pyrite or as individual grains associated mostly with chromite grains. In situ LA-ICP-MS analyses reveal that pentlandite carries distinctly elevated platinum-group element (PGE) contents. In contrast, pyrrhotite and chalcopyrite contain very low PGE concentrations. Pentlandite shows average maximum values of 350-1,000 ppm Pd, 200 ppm Rh, 130-175 ppm Ru, 20 ppm Os, and 150 ppm Ir, and is the principal host of Pd and Rh in the studied ores of the UG2. Mass balance calculations were conducted for samples representing the UG2 main seam of the drill core DT46, eastern Bushveld. Pentlandite consistently hosts elevated contents of the whole-rock Pd (up to 55 %) and Rh (up to 46 %), and erratic contents of Os (up to 50 %), Ir (2 to 17 %), and Ru (1-39 %). Platinum-group mineral (PGM) investigations support these mass balance results; most of the PGM are Pt-dominant such as braggite/cooperite and Pt-Fe alloys or laurite (carrying elevated concentrations of Os and Ir). Palladium and Rh-bearing PGM are rare. Both PGE concentrations and their distribution in base-metal sulfides (BMS) in the UG2 largely resemble that of the Merensky Reef, as most of the Pd and Rh are incorporated in pentlandite, whereas pyrrhotite, chalcopyrite, and pyrite are almost devoid of PGE.

  13. The mineralogy and mineral associations of platinum group elements and gold in the Platreef at Zwartfontein, Akanani Project, Northern Bushveld Complex, South Africa

    NASA Astrophysics Data System (ADS)

    van der Merwe, Frits; Viljoen, Fanus; Knoper, Mike

    2012-09-01

    The mineralogy of the platinum-group elements (PGE), and gold, in the Platreef of the Bushveld Complex, was investigated using an FEI Mineral Liberation Analyser. Polished sections were prepared from 171 samples collected from two boreholes, for the in-situ examination of platinum group minerals (PGM). PGM and gold minerals encountered include maslovite (PtBiTe, 32 area% of total PGM), kotulskite (Pd(BiTe), 17 %), isoferroplatinum (Pt3Fe, 15 %), sperrylite (PtAs2, 11 %), cooperite (PtS, 5 %), moncheite (PtTe2; 5 %), electrum (AuAg; 5 %), michenerite (PdBiTe; 3 %), Pd alloys (Pd, Sb, Sn; 3 %), hollingworthite ((Rh,Pt)AsS; 2 %), as well as minor (all <1 area% of total PGM) merenskyite (PdBiTe2), laurite (RuS2), rustenburgite (Pt0.4Pd0.4Sn0.2), froodite (PdBi2), atokite (Pd0.5Pt0.3Sn0.2), stumpflite (PtSb), plumbopalladinite (Pd3Pb2), and zvyagintsevite (Pd3Pb). An observed association of all PGM with base metal sulfides (BMS), and a pronounced association of PGE tellurides, arsenides and Pd&Pt alloys with secondary silicates, is consistent with the remobilisation and recrystallisation of some of the PGM's during hydrothermal alteration and serpentinisation subsequent to their initial (primary) crystallisation from BMS (e.g. Godel et al. J Petrol 48:1569-1604, 2007; Hutchinson and McDonald Appl Earth Sci (Trans Inst Min Metall B) 114:B208-224, 2008).

  14. Distribution of platinum-group elements in magmatic and altered ores in the Jinchuan intrusion, China: an example of selenium remobilization by postmagmatic fluids

    NASA Astrophysics Data System (ADS)

    Prichard, Hazel M.; Knight, Robert D.; Fisher, Peter C.; McDonald, Iain; Zhou, Mei-Fu; Wang, Christina Y.

    2013-08-01

    The division of platinum-group elements (PGE) between those hosted in platinum-group minerals (PGM) versus those in solid solution in base metal sulfides (BMS) has been determined for ores from the PGE-bearing Ni-Cu-rich Jinchuan intrusion in northwest China. All the BMS are devoid of Pt and Ir, and magmatic BMS are also barren of Rh. These PGE may have been scavenged by arsenic to form PGM during magmatic crystallization of the BMS. Pd, Os, and Ru are recorded in BMS and Pd is predominantly in solid solution in pentlandite. Unlike the fresh magmatic ores, in altered or serpentinized ores, Pd-PGM are present. Froodite is hosted in magnetite, formed during alteration of BMS, accompanied by sulfur loss and liberation of Pd. Michenerite ([Pd,Pt]BiTe), sperrylite (PtAs2), and Au-bearing PGM are located in altered silicates. Irarsite (IrAsS) occurs mainly enclosed in BMS. Padmaite (PdBiSe), identified at the junctions of magnetite and BMS, was the last PGM to form and locally partially replaces earlier non-Se-bearing PGM. We propose that padmaite formed under oxidizing conditions during late local remobilization of Se from the BMS. Se-bearing PGM are rare and our review shows they are frequently associated with carbonate, suggesting that Pd and Se can be mobilized great distances in low pH oxidizing fluids and may be precipitated on contact with carbonate. S/Se ratios are used by researchers of magmatic Ni-Cu-PGE ores to determine sulfur loss, assuming Se is immobile and representative of magmatic sulfur content. This study shows that Se as well as S is potentially mobile and this should be considered in the use of S/Se ratios.

  15. Search for a meteoritic component in drill cores from the Bosumtwi impact structure, Ghana: Platinum group element contents and osmium isotopic characteristics

    NASA Astrophysics Data System (ADS)

    McDonald, Iain; Peucker-Ehrenbrink, Bernhard; Coney, Louise; Ferrière, Ludovic; Reimold, Wolf Uwe; Koeberl, Christian

    An attempt was made to detect a meteoritic component in both crater-fill (fallback) impact breccias and fallout suevites (outside the crater rim) at the Bosumtwi impact structure in Ghana. Thus far, the only clear indication for an extraterrestrial component related to this structure has been the discovery of a meteoritic signature in Ivory Coast tektites, which formed during the Bosumtwi impact event. Earlier work at Bosumtwi indicated unusually high levels of elements that are commonly used for the identification of meteoritic contamination (i.e., siderophile elements, including the platinum group elements [PGE]) in both target rocks and impact breccias from surface exposures around the crater structure, which does not allow unambiguous verification of an extraterrestrial signature. The present work, involving PGE abundance determinations and Os isotope measurements on drill core samples from inside and outside the crater rim, arrives at the same conclusion. Despite the potential of the Os isotope system to detect even small amounts of extraterrestrial contribution, the wide range in PGE concentrations and Os isotope composition observed in the target rocks makes the interpretation of unradiogenic, high-concentration samples as an impact signature ambiguous.

  16. Platinum-group element signatures in the North Atlantic Igneous Province: Implications for mantle controls on metal budgets during continental breakup

    NASA Astrophysics Data System (ADS)

    Hughes, Hannah S. R.; McDonald, Iain; Kerr, Andrew C.

    2015-09-01

    The North Atlantic Igneous Province (NAIP) is a large igneous province (LIP) that includes a series of lava suites erupted from the earliest manifestations of the (proto)-Icelandic plume, through continental rifting and ultimate ocean opening. The lavas of one of these sub-provinces, the British Palaeogene Igneous Province (BPIP), were some of the first lavas to be erupted in the NAIP and overlie a thick crustal basement and sedimentary succession with abundant S-rich mudrocks. We present the first platinum-group element (PGE) and Au analyses of BPIP flood basalts from the main lava fields of the Isle of Mull and Morvern and the Isle of Skye, in addition to a suite of shallow crustal dolerite volcanic plugs on Mull, and other minor lavas suites. BPIP lavas display both S-saturated and S-undersaturated trends which, coupled with elevated PGE abundances (> MORB), suggest that the BPIP is one of the most prospective areas of the NAIP to host Ni-Cu-PGE-(Au) mineralisation in conduit systems. Platinum-group element, Au and chalcophile element abundances in lavas from West and East Greenland, and Iceland, are directly comparable to BPIP lavas, but the relative abundances of Pt and Pd vary systematically between lavas suites of different ages. The oldest lavas (BPIP and West Greenland) have a broadly chondritic Pt/Pd ratio (~ 1.9). Lavas from East Greenland have a lower Pt/Pd ratio (~ 0.8) and the youngest lavas from Iceland have the lowest Pt/Pd ratio of the NAIP (~ 0.4). Hence, Pt/Pd ratio of otherwise equivalent flood basalt lavas varies temporally across the NAIP and appears to be coincident with the changing geodynamic environment of the (proto)-Icelandic plume through time. We assess the possible causes for such systematic Pt/Pd variation in light of mantle plume and lithospheric controls, and suggest that this reflects a change in the availability of lithospheric mantle Pt-rich sulphides for entrainment in ascending plume magmas. Hence the precious metal

  17. Platinum group elements in gold-sulfide and base-metal ores of the Sayan-Baikal Fold Region and possible platinum and palladium speciation in sulfides

    NASA Astrophysics Data System (ADS)

    Mironov, A. G.; Zhmodik, S. M.; Kolesov, G. M.; Mit'kin, V. N.; Damdinov, B. B.; Zayakina, S. B.

    2008-02-01

    The concentration levels and distribution features of the platinum group elements (PGE) in quartz-sulfide and base-metal ores in deposits of the Sayan-Baikal Fold Region (SBFR) are discussed. Microfire assay neutron activation analysis (MF-NAA), which enables one to work on a nondestructive basis and allows one to avoid inaccuracies related to chemical sample preparation, was used as the main analytical technique. Three types of hydrothermal mineralization with elevated grades of PGE (especially Pt, Pd, and Ru) have been identified: (1) pyrite-pyrrhotite (massive sulfide) mineralization hosted in black shales of the Il’chir Sequence; (2) gold-sulfide ores of the Zun-Kholba, Tainsky, Kamenny, and some other gold deposits; and (3) silver-basemetal ores of the Dzhida-Vitim Zone. The PGE contents significantly vary, from global average values to tens of grams per ton. An absence of PGE minerals implies that these elements are finely dispersed in sulfide minerals and native gold. Taking into account difficulties in conversion of PGE into analytical forms, their nonuniform distribution in sulfide minerals, their high affinity to coordination compounds, and experimental results, cluster species of Pt and Pd in major minerals are suggested for the gold-sulfide and silver-base-metal ores in deposits, which are related to suprasubduction ophiolites and island-arc and intraplate settings in the SBFR.

  18. Increase in platinum group elements in Mexico City as revealed from growth rings of Taxodium mucronatum ten.

    PubMed

    Morton-Bermea, Ofelia; Beramendi-Orosco, Laura; Martínez-Reyes, Ángeles; Hernández-Álvarez, Elizabeth; González-Hernández, Galia

    2016-02-01

    Tree rings may be used as indicators of contamination events providing information on the chronology and the elemental composition of the contamination. In this framework, we report PGEs enrichment in growth rings of Taxodium mucronatum ten for trees growing in the central area of Mexico City as compared to trees growing in a non-urban environment. Concentrations of PGE were determined by ICP-MS analysis on microwave-digested tree rings. The element found in higher concentrations was Pd (1.13-87.98 μg kg(-1)), followed by Rh (0.28-36.81 μg kg(-1)) and Pt (0.106-7.21 μg kg(-1)). The concentration trends of PGEs in the tree-ring sequences from the urban area presented significant correlation values when comparing between trees (r between 0.618 and 0.98, P < 0.025) and between elements within individual trees (r between 0.76 and 0.994, P < 0.01). Furthermore, a clear increase was observed for rings after 1997, with enrichment of up to 60 times the mean concentration found for the sequence from the non-urban area and up to 40 times the mean concentration for the pre-1991 period in the urban trees. These results also demonstrate the feasibility of applying T. mucronatum ten to be used as a bioindicator of the increase in PGE in urban environments. PMID:25903068

  19. The pH-dependent release of platinum group elements (PGEs) from gasoline and diesel fuel catalysts: Implication for weathering in soils.

    PubMed

    Suchá, Veronika; Mihaljevič, Martin; Ettler, Vojtěch; Strnad, Ladislav

    2016-04-15

    Powdered samples of new and old gasoline catalysts (Pt, Pd, Rh) and new and old diesel (Pt) catalysts were subjected to a pH-static leaching procedure (pH 2-9) coupled with thermodynamic modeling using PHREEQC-3 to verify the release and mobility of PGEs (platinum group elements). PGEs were released under acidic conditions, mostly exhibiting L-shaped leaching patterns: diesel old: 5.47, 0.005, 0.02; diesel new: 68.5, 0.23, 0.11; gasoline old: 0.1, 11.8, 4.79; gasoline new 2.6, 25.2, 35.9 in mg kg(-1) for Pt, Pd and Rh, respectively. Only the new diesel catalyst had a strikingly different leaching pattern with elevated concentrations at pH 4, probably influenced by the dissolution of the catalyst carrier and washcoat. The pH-static experiment coupled with thermodynamic modeling was found to be an effective instrument for understanding the leaching behavior of PGEs under various environmental conditions, and indicated that charged Pt and Rh species may be adsorbed on the negatively charged surface of kaolinite or Mn oxides in the soil system, whereas uncharged Pd and Rh species may remain mobile in soil solutions. PMID:26874614

  20. Determination of the platinum - Group elements (PGE) and gold (Au) in manganese nodule reference samples by nickel sulfide fire-assay and Te coprecipitation with ICP-MS

    USGS Publications Warehouse

    Balaram, V.; Mathur, R.; Banakar, V.K.; Hein, J.R.; Rao, C.R.M.; Gnaneswara, Rao T.; Dasaram, B.

    2006-01-01

    Platinum group elements (PGE) and Au data in polymetallic oceanic ferromanganese nodule reference samples and crust samples obtained by inductively coupled plasma mass spectrometry (ICP-MS), after separation and pre-concentration by nickel sulfide fire-assay and Te coprecipitation, are presented. By optimizing several critical parameters such as flux composition, matrix matching calibration, etc., best experimental conditions were established to develop a method suitable for routine analysis of manganese nodule samples for PGE and Au. Calibrations were performed using international PGE reference materials, WMG-1 and WMS-1. This improved procedure offers extremely low detection limits in the range of 0.004 to 0.016 ng/g. The results obtained in this study for the reference materials compare well with previously published data wherever available. New PGE data arc also provided on some international manganese nodule reference materials. The analytical methodology described here can be used for the routine analysis of manganese nodule and crust samples in marine geochemical studies.

  1. Platinum Group Element (PGE) Abundances in Lava Flows Generated by the Hawaiian Plume: Insights into Plume Evolution

    NASA Astrophysics Data System (ADS)

    Shafer, J. T.; Neal, C. R.

    2003-12-01

    Picritic and high-MgO (7.7-24 wt.%) basalt samples from Detroit (/sim81-76 Ma) and Koko (/sim48 Ma) Seamounts along the ESC have been analyzed for PGEs (Ru, Rh, Pd, Ir, and Pt) allowing an examination of how the PGEs in lavas from the Hawaiian plume have changed over time. Major and trace element (including the PGEs) concentrations were quantified by ICP methods at the University of Notre Dame. See Ely et al. (1999, Chem. Geol. 157:219) for the PGE analytical method. Bennett et al. (2000) analyzed Hawaiian picrites and found PGE abundances slightly greater than average MORB and comparable to the low-PGE basaltic komatiites. These authors modeled the PGE abundances of these picrites by using variable amounts of residual sulfide during melting, such that Koolau (low PGE contents) formed from a relatively sulfide-rich source and Loihi (high PGEs) from a sulfide-poor source. Our PGE data from Detroit Seamount show slightly higher PGE abundances than Loihi and Kilauea, suggesting these picrites formed from a source lacking residual sulfide. These results suggest that, if the model of Bennett et al. (2000) is correct, the dilution of plume lava with MORB source, as hypothesized on the basis of depleted isotope ratios and lower trace element abundances than modern Hawaii (Keller et al., 2000, Nature 405:603; Kinman & Neal, 2002, Eos 83:F1282; Regelous et al., 2003, JPet 44:113), was not the controlling factor in PGE abundances. However, since MORB PGE concentrations are not substantially different than low-PGE Hawaiian picrites, incorporation of MORB material within the Hawaiian plume at Detroit Seamount would not have drastically reduced the PGE abundances. Koko Seamount has relatively high PGE concentrations (/sim3-12 times greater than those from Detroit lavas). This may be the result of a lack of residual sulfide facilitated by higher degrees of partial melting. Although our initial data are consistent with variable degrees of partial melting and/or source

  2. Formation and geochemical significance of micrometallic aggregates including fissiogenic platinum group elements in the Oklo natural reactor, Gabon

    NASA Astrophysics Data System (ADS)

    Kikuchi, Makiko; Hidaka, Hiroshi; Gauthier-Lafaye, François

    2010-08-01

    Metallic aggregates with a size of a few tens μm and consisting mainly of Ru, Rh, Pd, Te, Pb, As, Sb, S and Bi were found in the acid residue of SD37-S2/CD uraninite taken from Oklo natural reactor zone (RZ) 13. Quantitative analyses of major elements using an electron probe microanalyzer and in situ isotopic analyses of Zr, Mo, Ru, Pb and U using a sensitive high-resolution ion microprobe were performed on the metallic aggregates to determine the geochemical behaviors of fission products and actinides and to ascertain the processes of formation of the aggregates in the RZs. The chemical compositions of the aggregates investigated in this study are significantly different from those reported previously, showing lower Pb content and no correlation between the contents of Pb and S in the individual grains. The 235U/ 238U ratios in metallic aggregates vary significantly from 0.00478 to 0.01466, indicating chemical fractionation between U and Pu during the formation of the aggregates. The Pb isotopic data indicate that most of the Pb in the aggregates decayed from 2.05 Ga-old uraninite that existed in the RZ originally and that there was chemical fractionation between U and Pb in some aggregates. The Zr and Mo isotopic ratios, 90Zr/ 91Zr and 95Mo/ 97Mo, for most of the aggregates had small variations, which can be simply explained by constant separate mixing of fissiogenic and nonfissiogenic components. On the other hand, a large variation in the 99Ru/ 101Ru ratio (0.324-1.73) cannot be explained only by a two component mixing theory; thus, chemical fractionation between Tc and Ru during the reactor criticality is suggested. The large variations in the 235U/ 238U and 99Ru/ 101Ru isotopic ratios suggest that the aggregates formed under various redox conditions owing to the radiolysis of water.

  3. Sulfide-scale insights into platinum-group element behavior during carbonate mantle metasomatism and evolution of Spitsbergen lithospheric mantle

    NASA Astrophysics Data System (ADS)

    Kim, Nak Kyu; Choi, Sung Hi; Dale, Christopher W.

    2016-03-01

    We report combined Re-Os isotope and highly siderophile element data for whole-rock and whole-sulfide grains from Spitsbergen peridotites. The Os-Ir contents in whole-rocks are elevated compared to those of the primitive mantle, but the Pt-Pd-Re contents are depleted, reflecting refractory monosulfide solid solution (Mss) control during mantle melting. There are two general types of sulfide documented in global mantle samples: primary residual Mss with subchondritic Pd/Ir ratios and secondary metasomatic sulfides with suprachondritic Pd/Ir ratios. Most Spitsbergen sulfides have elevated Ir contents, and belong to the residual group. Most but not all Spitsbergen sulfides, however, are unusual in that they show a fractionation of Os (and Ru) from Ir which cannot be reconciled with a simple partial melting process. The Os(+ Ru) fractionation from Ir is most notable in a sample containing mantle-derived carbonate-bearing pockets. Infiltration of carbonate-rich S-undersaturated melt into the Spitsbergen lithospheric mantle may result in the formation of localized S-rich liquid by dissolving residual Mss. Such melt compositions may promote laurite crystallization before Mss, causing the combined depletion of Os + Ru relative to Ir in later-formed Mss. The Re-depletion model ages of residual sulfide grains from Spitsbergen peridotites coincide with crustal ages determined for Spitsbergen, indicating coupled mantle-crust evolution, and furthermore, they coincide with the previously proposed major peaks of pulsed crustal formation periods in Earth at ca. 2.7, 1.9 and 1.2 Ga.

  4. Platinum-group element distribution in base-metal sulfides of the Merensky Reef from the eastern and western Bushveld Complex, South Africa

    NASA Astrophysics Data System (ADS)

    Osbahr, Inga; Klemd, Reiner; Oberthür, Thomas; Brätz, Helene; Schouwstra, Robert

    2013-02-01

    Base-metal sulfides in magmatic Ni-Cu-PGE deposits are important carriers of platinum-group elements (PGE). The distribution and concentrations of PGE in pentlandite, pyrrhotite, chalcopyrite, and pyrite were determined in samples from the mineralized portion of four Merensky Reef intersections from the eastern and western Bushveld Complex. Electron microprobe analysis was used for major elements, and in situ laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) for trace elements (PGE, Ag, and Au). Whole rock trace element analyses were performed on representative samples to obtain mineralogical balances. In Merensky Reef samples from the western Bushveld, both Pt and Pd are mainly concentrated in the upper chromitite stringer and its immediate vicinity. Samples from the eastern Bushveld reveal more complex distribution patterns. In situ LA-ICP-MS analyses of PGE in sulfides reveal that pentlandite carries distinctly elevated PGE contents, whereas pyrrhotite and chalcopyrite only contain very low PGE concentrations. Pentlandite is the principal host of Pd and Rh in the ores. Palladium and Rh concentrations in pentlandite reach up to 700 and 130 ppm, respectively, in the samples from the eastern Bushveld, and up to 1,750 ppm Pd and up to 1,000 ppm Rh in samples from the western Bushveld. Only traces of Pt are present in the base-metal sulfides (BMS). Pyrrhotite contains significant though generally low amounts of Ru, Os, and Ir, but hardly any Pd or Rh. Chalcopyrite contains most of the Ag but carries only extremely low PGE concentrations. Mass balance calculations performed on the Merensky Reef samples reveal that in general, pentlandite in the feldspathic pyroxenite and the pegmatoidal feldspathic pyroxenite hosts up to 100 % of the Pd and Rh and smaller amounts (10-40 %) of the Os, Ir, and Ru. Chalcopyrite and pyrrhotite usually contain less than 10 % of the whole rock PGE. The remaining PGE concentrations, and especially most of the Pt (up to

  5. Effects of mother lode-type gold mineralization on 187Os/188Os and platinum group element concentrations in peridotite: Alleghany District, California

    USGS Publications Warehouse

    Walker, R.J.; Böhlke, J.K.; McDonough, W.F.; Li, J.

    2007-01-01

    Osmium isotope compositions and concentrations of Re, platinum group elements (PGE), and Au were determined for host peridotites (serpentinites and barzburgites) and hydrothermally altered ultramafic wall rocks associated with Mother Lode-type hydrothermal gold-quartz vein mineralization in the Alleghany district, California. The host peridotites have Os isotope compositions and Re, PGE, and Au abundances typical of the upper mantle at their presumed formation age during the late Proterozoic or early Paleozoic. The hydrothermally altered rocks have highly variable initial Os isotope compositions with ??os, values (% deviation of 187OS/188OS from the chondritic average calculated for the approx. 120 Ma time of mineralization) ranging from -1.4 to -8.3. The lowest Os isotope compositions are consistent with Re depletion of a chondritic source (e.g., the upper mantle) at ca. 1.6 Ga. Most of the altered samples are enriched in Au and have depleted and fractionated abundances of Re and PGE relative to their precursor peridotites. Geoehemical characteristics of the altered samples suggest that Re and some PGE were variably removed from the ultramafic rocks during the mineralization event. In addition to Re, the Pt and Pd abundances of the most intensely altered rocks appear to have been most affected by mineralization. The 187Os-depleted isotopic compositions of some altered rocks are interpreted to be a result of preferential 187Os loss via destruction of Re-rich phases during the event. For these rocks, Os evidently is not a useful tracer of the mineralizing fluids. The results do, however, provide evidence for differential mobility of these elements, and mobility of 187Os relative to the initial bulk Os isotope composition during hydrothermal metasomatic alteration of ultramafic rocks. ?? 2007 Society of Economic Geologists, Inc.

  6. Biological availability of traffic-related platinum-group elements (palladium, platinum, and rhodium) and other metals to the zebra mussel (Dreissena polymorpha) in water containing road dust.

    PubMed

    Zimmermann, Sonja; Alt, Friedrich; Messerschmidt, Jürgen; von Bohlen, Alex; Taraschewski, Horst; Sures, Bernd

    2002-12-01

    The uptake and bioaccumulation of 15 road dust metals by the zebra mussel (Dreissena polymorpha) were investigated in laboratory exposure studies with emphasis on the traffic-related platinum-group elements (PGEs) palladium (Pd), platinum (Pt), and rhodium (Rh). The biological availability of the metals may depend on water characteristics, so the mussels were maintained in two types of water: nonchlorinated tap water and humic water of a bog lake, both of which contained dust of a moderately frequented road. After an exposure period of 26 weeks, soft tissues of the mussels were freeze-dried and analyzed for the metals. The metal concentrations in the mussel soft tissue ranged from several hundred micrograms per gram (e.g., for iron [Fe]) to less than 10 ng/g (for PGEs). Metal uptake from the road dust by the mussels was found for the PGEs and silver (Ag), bismuth (Bi), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), Fe, lead (Pb), and antimony (Sb). After maintenance of mussels in road dust-contaminated tap water, bioaccumulation factors (BAF = (C(exposed mussels) - C(control mussels))/C(total metal, water), where c is concentration) decreased in the following order: Cu > Cd > Ag > Pd > Sb > Pb > Fe > Pt > Rh. The biological availability of most metals was enhanced by humic water as compared to tap water. Our results show a hitherto unrecognized high availability of Pd for the mussels. Thus, this metal should be monitored more intensively in the environment to assess its distribution in the biosphere. PMID:12463569

  7. Platinum-group element, Gold, Silver and Base Metal distribution in compositionally zoned sulfide droplets from the Medvezky Creek Mine, Noril'sk, Russia

    USGS Publications Warehouse

    Barnes, S.-J.; Cox, R.A.; Zientek, M.L.

    2006-01-01

    Concentrations of Ag, Au, Cd, Co, Re, Zn and Platinum-group elements (PGE) have been determined in sulfide minerals from zoned sulfide droplets of the Noril'sk 1 Medvezky Creek Mine. The aims of the study were; to establish whether these elements are located in the major sulfide minerals (pentlandite, pyrrhotite, chalcopyrite and cubanite), to establish whether the elements show a preference for a particular sulfide mineral and to investigate the model, which suggests that the zonation in the droplets is caused by the crystal fractionation of monosulfide solid solution (mss). Nickel, Cu, Ag, Re, Os, Ir, Ru, Rh and Pd, were found to be largely located in the major sulfide minerals. In contrast, less than 25% of the Au, Cd, Pt and Zn in the rock was found to be present in these sulfides. Osmium, Ir, Ru, Rh and Re were found to be concentrated in pyrrhotite and pentlandite. Palladium and Co was found to be concentrated in pentlandite. Silver, Cd and Zn concentrations are highest in chalcopyrite and cubanite. Gold and platinum showed no preference for any of the major sulfide minerals. The enrichment of Os, Ir, Ru, Rh and Re in pyrrhotite and pentlandite (exsolution products of mss) and the low levels of these elements in the cubanite and chalcopyrite (exsolution products of intermediate solid solution, iss) support the mss crystal fractionation model, because Os, Ir, Ru, Rh and Re are compatible with mss. The enrichment of Ag, Cd and Zn in chalcopyrite and cubanite also supports the mss fractionation model these minerals are derived from the fractionated liquid and these elements are incompatible with mss and thus should be enriched in the fractionated liquid. Gold and Pt do not partition into either iss or mss and become sufficiently enriched in the final fractionated liquid to crystallize among the iss and mss grains as tellurides, bismithides and alloys. During pentlandite exsolution Pd appears to have diffused from the Cu-rich portion of the droplet into

  8. Platinum-Group Elements in Kerguelen Plateau Basalts: a Tale of Crystal Fractionation, the Core-Mantle Boundary, and no Sulfide Segregation.

    NASA Astrophysics Data System (ADS)

    Chazey, W. J.; Neal, C. R.

    2001-12-01

    Basalt samples from the Kerguelen Plateau in the southern Indian Ocean (ODP Leg 183) were analyzed for major and trace elements including the platinum-group elements (PGEs: Os, Ir, Ru, Rh, Pt, Pd). PGE abundances range from 0.1 (Os-, Ir, Ru) to 5 times primitive mantle (i.e., Pt). Olivine and Cr-spinel were fractionating phases, which probably accentuated the depletion of Os, Ir, and Ru relative to Rh, Pt, and Pd in primitive mantle-normalized profiles. Primitive mantle-normalized profiles show a relatively flat transition form Pt and Pd to Y, although a slight negative Pd anomaly is present in some samples. Sulfide immiscibility has the potential to preferentially remove Pd, but would also deplete all of the PGEs relative to Y. Plots of PGE/Y vs. Y/Cu demonstrate that the Pd anomaly was not caused by separation of a sulfide-rich fluid. Downhole variation of Pt in the Site 1138 basalt sequence is similar to that of other incompatible elements demonstrating that Pt is behaving as a lithophile element and from which we infer that the magma is undersaturated with respect to S. Finally, if sulfide immiscibility had occurred, Ru/Ir ratios would increase due to the greater affinity of Ir for sulfide liquid (vs. silicate melt), but these ratios are within error of the primitive mantle value. The depletion in Pd is attributed to it being preferentially removed during secondary alteration of the KP basalts. There seems to be very little consistent variation in PGE concentrations between ODP Sites 1136, 1137, 1138, 1141 and 1142. The PGEs in Sites 1136, 1141, and 1142 samples are generally lower in abundance than those from Sites 1137 and 1138. Overall, the PGEs in the Kerguelen plateau basalts are present in relatively high abundances. When plotted with MORBs, for example, all of the Kerguelen basalts are much higher in abundance, even though the KP basalts are derived from a much higher degree of partial melting. Most MORBs, however, appear to have experienced sulfide

  9. Platinum-group element geochemistry of the Hongge Fe-V-Ti deposit in the Pan-Xi area, southwestern China

    NASA Astrophysics Data System (ADS)

    Zhong, Hong; Zhou, Xin-Hua; Zhou, Mei-Fu; Sun, Min; Liu, Bing-Guang

    2002-03-01

    Mafic and ultramafic intrusions in the Pan-Xi area along the western margin of the Yangtze block, southwestern China, are spatially associated with the Late Permian Emeishan flood basalts of the Emeishan Large Igneous Province. The Hongge layered intrusion is one of the plutonic bodies of this province and hosts a giant Fe-V-Ti deposit. This intrusion has three zones: a lower, olivine clinopyroxenite zone, a middle, clinopyroxenite zone, and an upper, gabbro zone. Each of these zones consists of one or two compositional cycles, which have distinct Mg# values, TiO2 concentrations and total REE contents. The middle clinopyroxenite zone and upper gabbro zone contain thick (14-84 m) magnetite-mineralized layers. Samples from the lower olivine clinopyroxenite zone and middle clinopyroxenite zone of the Hongge intrusion are enriched in platinum and palladium relative to iridium and ruthenium. Rocks of the lower olivine clinopyroxenite zone have Pd/Ir ratios (1.8-22.3) lower than those of the middle clinopyroxenite zone (6.2 to 83 in its lower part and 3.6 to 49 in its upper part). The Pd/Ir ratios increase progressively upwards in each cyclic unit. Chromite is the major phase controlling concentrations of iridium and ruthenium. The Cu/Pd ratios at the bottom of each cyclic unit are close to that of the mantle and increase upwards. This variation suggests that each cyclic unit represents a new batch of magma, and sulfide mineral segregation removes PGE (platinum-group elements), Ni and Cu. Each cyclic unit in the Hongge layered intrusion might have resulted from crystal fractionation and mixing between a primary and evolved magma. The high Cu/Pd, Ti/Pd, Ni/Pd and Cu/Ir ratios of the intrusion suggest that the sulfide mineral segregation may have played an important role in PGE differentiation. If this interpretation is correct, then there is a potential to find economic PGE-rich horizon in the Hongge-type intrusions in the region.

  10. Platinum-group elements (PGE) and rhenium in marine sediments across the Cretaceous-Tertiary boundary: constraints on Re-PGE transport in the marine environment

    NASA Astrophysics Data System (ADS)

    Lee, Cin-Ty Aeolus; Wasserburg, Gerald J.; Kyte, Frank T.

    The nature of Re-platinum-group element (PGE; Pt, Pd, Ir, Os, Ru) transport in the marine environment was investigated by means of marine sediments at and across the Cretaceous-Tertiary boundary (KTB) at two hemipelagic sites in Europe and two pelagic sites in the North and South Pacific. A traverse across the KTB in the South Pacific pelagic clay core found elevated levels of Re, Pt, Ir, Os, and Ru, each of which is approximately symmetrically distributed over a distance of ˜1.8 m across the KTB. The Re-PGE abundance patterns are fractionated from chondritic relative abundances: Ru, Pt, Pd, and Re contents are slightly subchondritic relative to Ir, and Os is depleted by ˜95% relative to chondritic Ir proportions. A similar depletion in Os (˜90%) was found in a sample of the pelagic KTB in the North Pacific, but it is enriched in Ru, Pt, Pd, and Re relative to Ir. The two hemipelagic KTB clays have near-chondritic abundance patterns. The ˜1.8-m-wide Re-PGE peak in the pelagic South Pacific section cannot be reconciled with the fallout of a single impactor, indicating that postdepositional redistribution has occurred. The elemental profiles appear to fit diffusion profiles, although bioturbation could have also played a role. If diffusion had occurred over ˜65 Ma, the effective diffusivities are ˜10 -13 cm 2/s, much smaller than that of soluble cations in pore waters (˜10 -6 cm 2/s). The coupling of Re and the PGEs during redistribution indicates that postdepositional processes did not significantly fractionate their relative abundances. If redistribution was caused by diffusion, then the effective diffusivities are the same. Fractionation of Os from Ir during the KTB interval must therefore have occurred during aqueous transport in the marine environment. Distinctly subchondritic Os/Ir ratios throughout the Cenozoic in the South Pacific core further suggest that fractionation of Os from Ir in the marine environment is a general process throughout geologic

  11. Platinum-group elements (PGE) and Rhenium in Marine Sediments across the Cretaceous-Tertiary Boundary: Constraints on Re-PGE Transport in the Marine Environment

    NASA Technical Reports Server (NTRS)

    Lee, Cin-Ty Aeolus; Wasserburg, Gerald J.; Kyte, Frank T.

    2003-01-01

    The nature of Re-platinum-group element (PGE; Pt, Pd, Ir, Os, Ru) transport in the marine environment was investigated by means of marine sediments at and across the Cretaceous-Tertiary boundary (KTB) at two hemipelagic sites in Europe and two pelagic sites in the North and South Pacific. A traverse across the KTB in the South Pacific pelagic clay core found elevated levels of Re, Pt, Ir, Os, and Ru, each of which is approximately symmetrically distributed over a distance of approx. 1.8 m across the KTB. The Re-PGE abundance patterns are fractionated from chondritic relative abundances: Ru, Pt, Pd, and Re contents are slightly subchondritic relative to Ir, and Os is depleted by approx. 95% relative to chondritic Ir proportions. A similar depletion in Os (approx. 90%) was found in a sample of the pelagic KTB in the North Pacific, but it is enriched in Ru, Pt, Pd, and Re relative to Ir. The two hemipelagic KTB clays have near-chondritic abundance patterns. The approx. 1.8-m-wide Re-PGE peak in the pelagic South Pacific section cannot be reconciled with the fallout of a single impactor, indicating that postdepositional redistribution has occurred. The elemental profiles appear to fit diffusion profiles, although bioturbation could have also played a role. If diffusion had occurred over approx. 65 Ma, the effective diffusivities are approx. 10(exp -13)sq cm/s, much smaller than that of soluble cations in pore waters (approx. 10(exp -5) sq cm/s). The coupling of Re and the PGEs during redistribution indicates that postdepositional processes did not significantly fractionate their relative abundances. If redistribution was caused by diffusion, then the effective diffusivities are the same. Fractionation of Os from Ir during the KTB interval must therefore have occurred during aqueous transport in the marine environment. Distinctly subchondritic Os/Ir ratios throughout the Cenozoic in the South Pacific core further suggest that fractionation of Os from Ir in the marine

  12. Abundances of platinum group elements in native sulfur condensates from the Niuatahi-Motutahi submarine volcano, Tonga rear arc: Implications for PGE mineralization in porphyry deposits

    NASA Astrophysics Data System (ADS)

    Park, Jung-Woo; Campbell, Ian H.; Kim, Jonguk

    2016-02-01

    Some porphyry Cu-Au deposits, which are enriched in Pd, are potentially an economic source of Pd. Magmatic volatile phases are thought to transport the platinum group elements (PGEs) from the porphyry source magma to the point of deposition. However, the compatibilities of the PGEs in magmatic volatile phases are poorly constrained. We report PGE and Re contents in native sulfur condensates and associated altered dacites from the Niuatahi-Motutahi submarine volcano, Tonga rear arc, in order to determine the compatibility of PGEs and Re in magmatic volatile phases, and their mobility during secondary hydrothermal alteration. The native sulfur we analyzed is the condensate of a magmatic volatile phase exsolved from the Niuatahi-Motutahi magma. The PGEs are moderately enriched in the sulfur condensates in comparison to the associated fresh dacite, with enrichment factors of 11-285, whereas Au, Cu and Re are strongly enriched with enrichment factors of ∼20,000, ∼5000 and ∼800 respectively. Although the PGEs are moderately compatible into magmatic volatile phases, their compatibility is significantly lower than that of Au, Cu and Re. Furthermore, the compatibility of PGEs decrease in the order: Ru > Pt > Ir > Pd. This trend is also observed in condensates and sublimates from other localities. PGE mineralization in porphyry Cu-Au deposits is characterized by substantially higher Pd/Pt (∼7-60) and Pd/Ir (∼100-10,500) than typical orthomagmatic sulfide deposits (e.g. Pd/Pt ∼0.6 and Pd/Ir ∼20 for the Bushveld). It has previously been suggested that the high mobility of Pd, relative to the other PGEs, may account for the preferential enrichment of Pd in porphyry Cu-Au deposits. However, the low compatibility of Pd in the volatile phase relative to the other PGEs, shown in this study, invalidates this explanation. We suggest that the PGE geochemistry of Pd-rich Cu-Au deposits is principally derived from the PGE characteristics of the magma from which the ore

  13. Ages and sources of components of Zn-Pb, Cu, precious metal, and platinum group element deposits in the goodsprings district, clark county, Nevada

    USGS Publications Warehouse

    Vikre, P.; Browne, Q.J.; Fleck, R.; Hofstra, A.; Wooden, J.

    2011-01-01

    The Goodsprings district, Clark County, Nevada, includes zinc-dominant carbonate replacement deposits of probable late Paleozoic age, and lead-dominant carbonate replacement deposits, copper ?? precious metal-platinum group element (PGE) deposits, and gold ?? silver deposits that are spatially associated with Late Triassic porphyritic intrusions. The district encompasses ??500 km2 although the distribution of all deposits has been laterally condensed by late Mesozoic crustal contraction. Zinc, Pb, and Cu production from about 90 deposits was ??160,000 metric tons (t) (Zn > Pb >> Cu), 2.1 million ounces (Moz) Ag, 0.09 Moz Au, and small amounts of PGEs-Co, V, Hg, Sb, Ni, Mo, Mn, Ir, and U-were also recovered. Zinc-dominant carbonate replacement deposits (Zn > Pb; Ag ?? Cu) resemble Mississippi Valley Type (MVT) Zn-Pb deposits in that they occur in karst and fault breccias in Mississippian limestone where the southern margin of the regional late Paleozoic foreland basin adjoins Proterozoic crystalline rocks of the craton. They consist of calcite, dolomite, sphalerite, and galena with variably positive S isotope compositions (??34S values range from 2.5-13%), and highly radiogenic Pb isotope compositions (206Pb/204Pb >19), typical of MVT deposits above crystalline Precambrian basement. These deposits may have formed when southward flow of saline fluids, derived from basinal and older sedimentary rocks, encountered thinner strata and pinch-outs against the craton, forcing fluid mixing and mineral precipitation in karst and fault breccias. Lead-dominant carbonate replacement deposits (Pb > Zn, Ag ?? Cu ?? Au) occur among other deposit types, often near porphyritic intrusions. They generally contain higher concentrations of precious metals than zinc-dominant deposits and relatively abundant iron oxides after pyrite. They share characteristics with copper ?? precious metal- PGE and gold ?? silver deposits including fine-grained quartz replacement of carbonate minerals in

  14. Multiple magma evolution and ore-forming processes of the Hongge layered intrusion, SW China: Insights from Sr-Nd isotopes, trace elements and platinum-group elements

    NASA Astrophysics Data System (ADS)

    Liao, Mingyang; Tao, Yan; Song, Xieyan; Li, Yubang; Xiong, Feng

    2015-12-01

    The Hongge layered intrusion (259 Ma), which is located in the inner zone of the Emeishan large igneous province (ELIP), is one of the most typical Fe-Ti-V ore deposits in the Pan-Xi area. Mafic-ultramafic layered intrusions of the ELIP have attracted a lot of attention lately because these intrusions host world class Fe-Ti-V oxide deposits plus interesting Cu-Ni-(PGE) mineralization which may have economic potential. This paper, reports new whole-rock major and trace element compositions, PGE abundances and Sr-Nd isotopic data for selected cumulate rocks and basalts. We use these data to investigate the nature of parental magmas and the controls on its evolution from the source mantle en route to the surface involving the Hongge ore-bearing intrusion. Two abrupt changes in Mt/Ilm and trace element ratios such as Ba/Th with depths in the Hongge layered intrusion indicate that this intrusion formed by at least two pluses of relatively primitive magma. The whole rock Sr-Nd isotopic data of basaltic and intrusive rocks plot in the region of Emeishan low-Ti basalts and the compositions of residual liquid (at ∼1260 °C and 1155 °C) calculated by MELTS are similar to our actual high-Ti (BFQ-2) and low-Ti (BC-1) basltic samples, indicate they are co-magmatic rather than derivation from a distinct source. Total PGE abundances in the Hongge samples are extremely low, ranging from 0.5 to 10 ppb. Sulfide-bearing rocks in the Hongge intrusion and the nearby coeval Banfangqing and Baicao basalts have similar mantle-like Pd/Pt ratios (2-6) and extremely high Cu/Pd ratios (3 × 104 to 4 × 105), indicating that sulfide segregation took place at depth prior to emplacement at Hongge and eruption in this region. Sulfide saturation in the Hongge magma may have resulted from such crustal contamination event. Crystallization of silicate minerals under the anhydrous magma, magma hydration plus Fe-Ti enrichments in the parental magma are three critical factors for the formation of Fe

  15. Platinum group nuggets in deep sea sediments

    NASA Technical Reports Server (NTRS)

    Brownlee, D. E.; Bates, B. A.; Wheelock, M. M.

    1984-01-01

    The existence of iron meteor oblation spheres in deep sea sediments was known for over a century. These spheres generally were believed to be composed of either pure magnetite and wustite or an oxide shell surrounding a NiFe metal core. A large number of 300 micron to 600 micron spheres found were pure oxide spheres, usually containing a solitary 10 micron platinum group nugget (pgn) composed almost entirely of group VIII metals. Twelve PGN's were analyzed and most had chondritic abundances with some depletions that correlate with element volatility. PGN formation by oxidation of a molten metal sphere entering the atmosphere cannot occur if the oxygen abundance in the atmosphere is less than half of its present value. The first appearance of PGN's in the geological record should mark when, in the Earth's history, oxygen rose to this level.

  16. Mineral resource of the month: platinum-group metals

    USGS Publications Warehouse

    Hilliard, Henry

    2003-01-01

    The precious metals commonly referred to as platinum-group metals (PGM) include iridium, osmium, palladium, platinum, rhodium and ruthenium. PGM are among the rarest of elements, and their market values — particularly for palladium, platinum and rhodium — are the highest of all precious metals.

  17. Concentration of some platinum-group metals in coal

    USGS Publications Warehouse

    Finkelman, R.B.; Aruscavage, P. J.

    1981-01-01

    New data on some platinum group metals in coal indicate that the concentration of Pt is generally less than about 5 ppb, that of Pd is generally less than 1 ppb, and that of Rh is generally less than 0.5 ppb. No conclusive evidence was obtained concerning the mode of occurrence of these elements in coal. ?? 1981.

  18. Multi-elemental characterization of tunnel and road dusts in Houston, Texas using dynamic reaction cell-quadrupole-inductively coupled plasma-mass spectrometry: evidence for the release of platinum group and anthropogenic metals from motor vehicles.

    PubMed

    Spada, Nicholas; Bozlaker, Ayse; Chellam, Shankararaman

    2012-07-20

    Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma-mass spectrometry (DRC-q-ICP-MS). Average Rh, Pd and Pt concentrations were 152±52, 770±208 and 529±130 ng g(-1) respectively in tunnel dusts while they varied between 6 and 8 ng g(-1), 10 and 88 ng g(-1) and 35 and 131 ng g(-1) in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However, all other elements including rare earths most likely arose from weathering, erosion and resuspension of crustal material. These are the first such detailed measurements in Houston, the largest city in TX and fourth largest in the United States. We posit that such investigations will assist in better understanding PGE concentrations in urban environments while providing elemental data necessary to better understand

  19. Extraterrestrial platinum group nuggets in deep-sea sediments

    NASA Technical Reports Server (NTRS)

    Brownlee, D. E.; Bates, B. A.; Wheelock, M. M.

    1984-01-01

    A previously unrecognized property of iron cosmic spheres is reported. The most common spheres larger than 300 microns do not, in fact, contain FeNi metal cores, but instead contain a micrometer-sized nugget composed almost entirely of platinum group elements. These elements appear to have been concentrated by the oxidation of molten meteoritic metal during atmospheric entry. This process is critically dependent on the relative abundance of oxygen in the atmosphere, and the first appearance of the nuggets in the geological record may provide a marker indicating when the oxygen abundance attained half of its present level.

  20. Re-Os isotope and platinum-group element geochemistry of the Pobei Ni-Cu sulfide-bearing mafic-ultramafic complex in the northeastern part of the Tarim Craton

    NASA Astrophysics Data System (ADS)

    Yang, Sheng-Hong; Zhou, Mei-Fu; Lightfoot, Peter C.; Xu, Ji-Feng; Wang, Christina Yan; Jiang, Chang-Yi; Qu, Wen-Jun

    2014-03-01

    A number of mafic-ultramafic intrusions that host Ni-Cu sulfide mineralization occur in the northeastern Tarim Craton and the eastern Tianshan Orogenic Belt (NW China). The sulfide-mineralized Pobei mafic-ultramafic complex is located in the northeastern part of the Tarim Craton. The complex is composed of gabbro and olivine gabbro, cut by dunite, wehrlite, and melatroctolite of the Poyi and Poshi intrusions. Disseminated Ni-Cu sulfide mineralization is present towards the base of the ultramafic bodies. The sulfide mineralization is typically low grade (<0.5 wt.% Ni and <2 wt.% S) with low platinum-group element (PGE) concentrations (<24.5 ppb Pt and <69 ppb Pd); the abundance of Cu in 100 % sulfide is 1-8 wt.%, and Ni abundance in 100 % sulfide is typically >4 wt.%. Samples from the Pobei complex have ɛNd (at 280 Ma) values up to +8.1, consistent with the derivation of the magma from an asthenospheric mantle source. Fo 89.5 mol.% olivine from the ultramafic bodies is consistent with a primitive parental magma. Sulfide-bearing dunite and wehrlite have high Cu/Pd ratios ranging from 24,000 to 218,000, indicating a magma that evolved under conditions of sulfide saturation. The grades of Ni, Cu, and PGE in 100 % sulfide show a strong positive correlation. A model for these variations is proposed where the mantle source of the Pobei magma retained ~0.033 wt.% sulfide during the production of a PGE-depleted parental magma. The parental magma migrated from the mantle to the crust and underwent further S saturation to generate the observed mineralization along with its high Cu/Pd ratio at an R-factor varying from 100 to 1,200. The mineralization at Poshi and Poyi has very high γOs (at 280 Ma) values (+30 to +292) that are negatively correlated with the abundance of Os in 100 % sulfide (5.81-271 ppb) and positively correlated with the Re/Os ratios; this indicates that sulfide saturation was triggered by the assimilation of crustal sulfide with both high γOs and Re

  1. Platinum-group elements distribution and spinel composition in podiform chromitites and associated rocks from the upper mantle section of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco

    NASA Astrophysics Data System (ADS)

    Ahmed, Ahmed H.; Arai, Shoji; Abdel-Aziz, Yaser M.; Ikenne, Moha; Rahimi, Abdellatif

    2009-09-01

    The distribution of platinum-group elements (PGEs), together with spinel composition, of podiform chromitites and serpentinized peridotites were examined to elucidate the nature of the upper mantle of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco. The mantle section is dominated by harzburgite with less abundant dunite. Chromitite pods are also found as small lenses not exceeding a few meters in size. Almost all primary silicates have been altered, and chromian spinel is the only primary mineral that survived alteration. Chromian spinel of chromitites is less affected by hydrothermal alteration than that of mantle peridotites. All chromitite samples of the Bou Azzer ophiolite display a steep negative slope of PGE spidergrams, being enriched in Os, Ir and Ru, and extremely depleted in Pt and Pd. Harzburgites and dunites usually have intermediate to low PGE contents showing more or less unfractionated PGE patterns with conspicuous positive anomalies of Ru and Rh. Two types of magnetite veins in serpentinized peridotite, type I (fibrous) and type II (octahedral), have relatively low PGE contents, displaying a generally positive slope from Os to Pd in the former type, and positive slope from Os to Rh then negative from Rh to Pd in the latter type. These magnetite patterns demonstrate their early and late hydrothermal origin, respectively. Chromian spinel composition of chromitites, dunites and harzburgites reflects their highly depleted nature with little variations; the Cr# is, on average, 0.71, 0.68 and 0.71, respectively. The TiO 2 content is extremely low in chromian spinels, <0.10, of all rock types. The strong PGE fractionation of podiform chromitites and the high-Cr, low-Ti character of spinel of all rock types imply that the chromitites of the Bou Azzer ophiolite were formed either from a high-degree partial melting of primitive mantle, or from melting of already depleted mantle peridotites. This kind of melting is most easily accomplished in the

  2. Computational Study of Platinum Group Superalloys

    NASA Astrophysics Data System (ADS)

    Popoola, A. I.; Lowther, J. E.

    2014-02-01

    Various properties of substitutional alloys formed from aluminium and the platinum group metals (PGMs) are examined using density functional (D-F) theory and show strong variations depending on metal type. A similar pattern for the binary alloys is observed using molecular dynamics modeling employing Sutton Chen potentials. All results suggest that several of the PGMs could have superior properties to the presently used Ni3Al alloy for high temperature applications. Some phases are predicted to be stable with extremely high melting temperatures (MTs).

  3. Exhaust system having a gold-platinum group metal catalyst

    DOEpatents

    Ragle, Christie Susan; Silver, Ronald G.; Zemskova, Svetlana Mikhailovna; Eckstein, Colleen J.

    2011-12-06

    A method of providing an exhaust treatment device is disclosed. The method includes applying a catalyst including gold and a platinum group metal to a particulate filter. The concentration of the gold and the platinum group metal is sufficient to enable oxidation of carbon monoxide and nitric oxide.

  4. Exhaust system having a gold-platinum group metal catalyst

    DOEpatents

    Ragle, Christie Susan; Silver, Ronald G.; Zemskova, Svetlana Mikhailovna; Eckstein, Colleen J.

    2012-08-07

    A method of providing an exhaust treatment device is disclosed. The method includes applying a catalyst including gold and a platinum group metal to a particulate filter. The concentration of the gold and the platinum group metal is sufficient to enable oxidation of carbon monoxide and nitric oxide.

  5. Elemental accumulation studied in biological species

    SciTech Connect

    Not Available

    1986-01-01

    At The Geysers, relatively little environmental baseline data were collected during the early years of development. In early 1983, the CEC awarded Sonoma County a geothermal grant to analyze the biological accumulation of trace elements in The Geysers Geothermal region. Prior studies in The Geysers region have established data for 27 different chemical elements, and suggest that chemicals are accumulating near power plants. This study examined selected species of rodents, fish, and lichen. Elevated amounts of chemical elements were found in their tissues. It is not clear if this accumulation is the result of geothermal development or due to naturally high backgrounds of these elements in the region. However, today these element loads serve as reference points for both developers and regulators. The CEC awarded a second grant in July 1985. The study funded by this grant will provide a more complete analysis of elemental loads by examining species such as western fence lizards and deer. Results and conclusions from these two studies can be used by regulatory agencies planning for future geothermal development in The Geysers region.

  6. Contamination from gold and platinum-group metals mining in the Gulf of Darién, Colombia

    NASA Astrophysics Data System (ADS)

    Vasquez-Bedoya, L.; Palacio Baena, J.

    2013-12-01

    Gulf of Darién, triangular southernmost extension of the Caribbean Sea, bounded by Panama on the southwest and by Colombia on the southeast and east. The Gulf is made up of 17 municipalities in the department of Choco and Antioquia. The Gulf of Darién is a geostrategic region, rich in biodiversity, known for its natural resources of minerals, oil, lumber as well as its water and fertile land. The Darién also acts as the bridge between South America and Central America and has access to the Pacific Ocean and the Caribbean Sea. The economy in the region is based mainly on agribusinesses, tourism and mining activities, mainly the 'mining of gold and platinum-group metals'. In our study we determined the degree of trace element contamination in estuarine sediment samples originated from mining activities and municipal waste water discharges of effluents on the gulf of Darién. . Surface samples were taken from 17 locations through the entire Gulf. Grain size, Corg, Ag, Al, Ca , Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb and Zn concentrations were analyzed, and enrichment factors (EF) as well as geo-accumulation indices (Igeo) were calculated. Concentrations of Pb, Zn, Ni, Cu and Cr show levels that are consistent with those typically found in urbanized marine environments. EF and Igeo values revealed that the Gulf is extremely contaminated with Ag and moderately contaminated with Cr and Zn. The sources of Cr, Ag, Hg and Zn are associated with the development of mining activities in the Atrato River basin. The observed enrichment of Ag may be explained as a residue of the extraction of gold and platinum-group metals.

  7. Partitioning of platinum-group elements (PGE) and chalcogens (Se, Te, As, Sb, Bi) between monosulfide-solid solution (MSS), intermediate solid solution (ISS) and sulfide liquid at controlled fO2-fS2 conditions

    NASA Astrophysics Data System (ADS)

    Liu, Yanan; Brenan, James

    2015-06-01

    In order to better understand the behavior of highly siderophile elements (HSEs: Os, Ir, Ru, Rh, Pt, Pd, Au, Re), Ag, Pb and chalcogens (As, Se, Sb, Te and Bi) during the solidification of sulfide magmas, we have conducted a series of experiments to measure partition coefficients (D values) between monosulfide solid solution (MSS) and sulfide melt, as well as MSS and intermediate solid solution (ISS), at 0.1 MPa and 860-926 °C, log fS2 -3.0 to -2.2 (similar to the Pt-PtS buffer), with fO2 controlled at the fayalite-magnetite-quartz (FMQ) buffer. The IPGEs (Os, Ir, Ru), Rh and Re are found to be compatible in MSS relative to sulfide melt with D values ranging from ∼20 to ∼5, and DRe/DOs of ∼0.5. Pd, Pt, Au, Ag, Pb, as well as the chalcogens, are incompatible in MSS, with D values ranging from ∼0.1 to ∼1 × 10-3. For the same metal/sulfur ratio, D values for the IPGEs, Rh and Re are systematically larger than most past studies, correlating with higher oxygen content in the sulfide liquid, reflecting the significant effect of oxygen on increasing the activity coefficients for these elements in the melt phase. MSS/ISS partitioning experiments reveal that Ru, Os, Ir, Rh and Re are partitioned into MSS by a factor of >50, whereas Pd, Pt, Ag, Au and the chalcogens partition from weakly (Se, As) to strongly (Ag, Au) into ISS. Uniformly low MSS- and ISS- melt partition coefficients for the chalcogens, Pt, Pd, Ag and Au will lead to enrichment in the residual sulfide liquid, but D values are generally too large to reach early saturation in Pt-Pd-chalcogen-rich accessory minerals, based on current solubility estimates. Instead, these phases likely precipitate at the last dregs of crystallization. Modeled evolution curves for the PGEs and chalcogens are in reasonably good agreement with whole-rock sulfide compositions for the McCreedy East deposit (Sudbury, Ontario), consistent with an origin by crystallization of MSS, then MSS + ISS from sulfide magma.

  8. Occurrence model for magmatic sulfide-rich nickel-copper-(platinum-group element) deposits related to mafic and ultramafic dike-sill complexes: Chapter I in Mineral deposit models for resource assessment

    USGS Publications Warehouse

    Schulz, Klaus J.; Woodruff, Laurel G.; Nicholson, Suzanne W.; Seal, Robert R., II; Piatak, Nadine M.; Chandler, Val W.; Mars, John L.

    2014-01-01

    The sulfides in magmatic Ni-Cu deposits generally constitute a small volume of the host rock(s) and tend to be concentrated in the lower parts of the mafic and/or ultramafic bodies, often in physical depressions or areas marking changes in the geometry of the footwall topography. In most deposits, the sulfide mineralization can be divided into disseminated, matrix or net, and massive sulfide, depending on a combination of the sulfide content of the rock and the silicate texture. The major Ni-Cu sulfide mineralogy typically consists of an intergrowth of pyrrhotite (Fe7S8), pentlandite ([Fe, Ni]9S8), and chalcopyrite (FeCuS2). Cobalt, PGE, and gold (Au) are extracted from most magmatic Ni-Cu ores as byproducts, although such elements can have a significant impact on the economics in some deposits, such as the Noril’sk-Talnakh deposits, which produce much of the world’s palladium. In addition, deposits may contain between 1 and 15 percent magnetite associated with the sulfides.

  9. Chalcophile and platinum-group element distribution in the Ultramafic series of the Stillwater Complex, MT, USA—implications for processes enriching chromite layers in Os, Ir, Ru, and Rh

    NASA Astrophysics Data System (ADS)

    Barnes, Sarah-Jane; Pagé, P.; Prichard, H. M.; Zientek, M. L.; Fisher, P. C.

    2016-01-01

    All of the rocks from the Ultramafic series of the Stillwater Complex are enriched in PGE relative to most mafic magmas. Furthermore, the chromite layers are particularly enriched in IPGE (Os, Ir, and Ru) and Rh. This enrichment appears to be a common characteristic of ultramafic rocks from many types of settings, layered intrusions, ophiolites, and zoned complexes. We have carried out a petrological, mineralogical, and geochemical study to assess how the enrichment occurred in the case of the Stillwater Complex and applied our results to the chromite layers of the Bushveld and Great Dyke complexes. The minerals that now host the PGE are laurite and fine-grained intergrowths of pentlandite, millerite, and chalcopyrite. The laurite occurs as inclusions in chromite, and mass balance calculations indicate that it hosts most of the Os, Ir, and Ru. The sulfide minerals occur both as inclusions in chromite and as interstitial grains. The sulfides host much of the Pd and Rh. The IPGE and Rh correlate with Cr but not with S or Se, indicating that these elements were not collected by a sulfide liquid. Palladium, Cu, and Se correlate with each other, but not with S. The low S/Se (<1500) of the whole rock and magnetite rims around the sulfides indicate some S has been lost from the rocks. We conclude that to account for all observations, the IPGE and Rh were originally collected by chromite, and subsequently, small quantities of base metal sulfide liquid was added to the chromite layers from the overlying magma. The IPGE and Rh in the chromite diffused from the chromite into the base metal sulfides and converted some of the sulfides to laurite.

  10. International strategic minerals inventory summary report: platinum-group metals

    USGS Publications Warehouse

    Sutphin, David M.; Page, Norman J

    1986-01-01

    Major world resources of platinum-group metals are described in this summary report of information in the International Strategic Minerals Inventory {ISMI}. ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, and the United States of America. This report, designed to be of benefit to policy analysts, contains two parts. Part I presents an overview of the resources and potential supply of platinum-group metals on the basis of inventory information. Part II contains tables of some of the geologic information and mineral-resource and production data that were collected by ISMI participants.

  11. Mineral resource of the month: platinum group metals

    USGS Publications Warehouse

    Loferski, Patricia J.

    2010-01-01

    The article focuses on platinum group metals (PGMs) and their properties. According to the author, PGMs, which include iridium, osmium, palladium, platinum, rhodium, and ruthenium, are among the rarest mineral commodities in the Earth's crust. PGMs are primarily used as catalytic converters that clean harmful exhaust from vehicle engines. They are also used in the chemical industry as catalysts in the production of nitric acid and in the petroleum refining industry.

  12. Platinum group elements in the environment: emissions and exposure.

    PubMed

    Dubiella-Jackowska, Aleksandra; Polkowska, Zaneta; Namieńnik, Jacek

    2009-01-01

    PGEs (Pt, Pd, Ru, Ir, and Os) are a relatively new group of anthropogenic pollutants. Specific useful properties of these metals (high resistance to chemical corrosion over a wide range of temperatures, high melting point, high mechanical resistance, and high plasticity) have fomented rapid growth of new and existing applications in various economic and industrial sectors. These metals are not only used in the chemical, petrochemical, electrical, and electronics industries but also PGE use, in various industries, has dramatically increased emissions of these metals to the environment; emissions from vehicle catalytic converters and hospital wastewater discharges are particularly significant. The environmental benefits of using PGEs in vehicle catalytic converters are clear. These metals catalyze the conversion of toxic constituents of exhaust fumes (CO, HCs, NOxs) to water, CO2, and molecular nitrogen. As a result of adverse physico-chemical and mechanical influences on the catalyst surface, PGEs are released from this layer and are emitted into the environment in exhaust fumes. Research results indicate that the levels of such emissions are rather low (ng km(-1)). However, recent data show that certain chemical forms of PGEs emitted from vehicles are, or may be, bioavailable. Hence, the potential for PGEs to bioaccumulate in different environmental compartments should be studied, and, if necessary, addressed. The use of Pt in anticancerous drug preparations also contributes to environmental burdens. Pt, when administered as a drug, is excreted in a patient's urine and, as a consequence, has been observed in hospital and communal wastewater discharges. Few studies have been published that address bioavailability, mode of penetration into live organisms, or environmental fate of PGEs. The toxic effect of these metals on living organisms, including humans, is still in dispute and incompletely elucidated. Contrary to some chlorine complexes of Pt, which most frequently cause allergic reactions, the metallic forms of PGEs are probably inert; however, they may undergo transformation to biologically available forms after release to the environment. Because exposure to PGEs may result in health hazards, it is necessary to evaluate the risks of human exposure to these metals. Available data show that the highest exposed groups (Leceniewska et al. 2001) are individuals who work in refineries, chemical plants, electronics plants, jewelry production, oncological wards (medical personnel), and road maintenance; also highly exposed are women who have silicone breast implants. The effects of PGE exposure in live organisms include the following: asthma, miscarriage, nausea, hair loss, skin diseases, and, in humans, other serious health problems. As production and use of PGEs grow, there is a commensurate need to generate additional experimental and modeling data on them; such data would be designed to provide a better understanding of the environmental disposition and influence on human health of the PGEs. PMID:19110940

  13. Photochemistry and charge transfer chemistry of the platinum group elements

    SciTech Connect

    Eisenberg, R.

    1992-12-01

    During the past 3 years, progress was made in elucidating the excited state structures of Pt(diimine)(dithiolate) complexes, while more recent efforts focused on the photochemistry of these complexes and electronic structure of other dithiolate systems. A carbonyl-Ir-maleonitrile dithiolate complex is also studied.

  14. Separation of platinum group metal ions by Donnan dialysis

    SciTech Connect

    Brajter, K.; Slonawska, K.; Cox, J.A.

    1985-10-01

    Separations of metal ions on the basis of Donnan dialysis across anion-exchange membranes should be possible if the receiver electrolyte composition favors the formation of selected anionic complexes of the sample metal ions. Moreover, such a separation has the possibility of being better suited from some applications than batch or column experiments with anion-exchange resins. The above hypothesis are tested on the platinum-group metal ions, Pt(IV), Rh(III), Pd(II), Ir(III), and Ir(IV). 13 references, 4 tables.

  15. Recent strikes in South Africa’s platinum-group metal mines: effects upon world platinum-group metal supplies

    USGS Publications Warehouse

    Yager, Thomas R.; Soto-Viruet, Yadira; Barry, James J.

    2012-01-01

    The recent labor disputes over wages and working conditions that have affected South Africa’s three leading platinum-group metal (PGM) producers have affected an industry already plagued by market pressures and labor unrest and raised the specter of constraints in the world’s supply of these metals. Although low demand for these metals in 2011 and 2012 helped to offset production losses of recent years, and particularly those losses caused by the strikes in 2012, a prolonged resumption of strikes could cause severe shortages of iridium, platinum, rhodium, ruthenium, and, to a lesser extent, palladium.

  16. Platinum group minerals (PGM) in the Falcondo Ni-laterite deposit, Loma Caribe peridotite (Dominican Republic)

    NASA Astrophysics Data System (ADS)

    Aiglsperger, Thomas; Proenza, Joaquin A.; Zaccarini, Federica; Lewis, John F.; Garuti, Giorgio; Labrador, Manuel; Longo, Francisco

    2015-01-01

    Two Ni-laterite profiles from the Loma Caribe peridotite (Dominican Republic) have been investigated for their platinum group element (PGE) geochemistry and mineralogy. One profile (Loma Peguera) is characterized by PGE-enriched (up to 3.5 ppm total PGE) chromitite bodies incorporated within the saprolite, whereas the second profile is chromitite-free (Loma Caribe). Total PGE contents of both profiles slightly increase from parent rocks (36 and 30 ppb, respectively) to saprolite (˜50 ppb) and reach highest levels within the limonite zone (640 and 264 ppb, respectively). Chondrite-normalized PGE patterns of saprolite and limonite reveal rather flat shapes with positive peaks of Ru and Pd. Three types of platinum group minerals (PGM) were found by using an innovative hydroseparation technique: (i) primary PGM inclusions in fresh Cr-spinel (laurite and bowieite), (ii) secondary PGM (e.g., Ru-Fe-Os-Ir compounds) from weathering of preexisting PGM (e.g., serpentinization and/or laterization), and (iii) PGM precipitated after PGE mobilization within the laterite (neoformation). Our results provide evidence that (i) PGM occurrence and PGE enrichment in the laterite profiles is independent of chromitite incorporation; (ii) PGE enrichment is residual on the profile scale; and (iii) PGE are mobile on a local scale leading to in situ growth of PGM within limonite, probably by bioreduction and/or electrochemical metal accretion.

  17. Donnan dialysis of bromocomplexes of some platinum group metal ions

    SciTech Connect

    Brajter, K.; Slonawska, K. ); Cox, J.A. )

    1989-03-01

    The separation of bromocomplexes of platinum group metals by Donnan dialysis is demonstrated with both anion and cation exchange membranes. The inclusion of ethylenediamine (en) in the sample improves the separation of Pd(II) from Pt(IV) with experiments performed with an anion exchange membrane and decreases the amount of metal retained on the membrane phase. With a cation exchange membrane, the addition of a ligand such as en is required for transport. With 5.6 mM en in the sample at pH 10, 74% of Pd(II) is transported across an anion exchange membrane into 0.5 M NH{sub 4} Br after 6 hours while only 8% of the Pt(IV) is dialyzed. Rhodium(III) and iridium(III) behave like Pt(IV). Using a cation exchange membrane under the same conditions except with a 1 hour dialysis results in a 30-fold preferential preconcentration of Pd(II) relative to Pt(IV), and, based on the amount retained in the membrane, a preconcentration of Ir(III) which exceeds that of Pd(II) and Pt(IV) by factors of 40 and 20, respectively.

  18. Modeling platinum group metal complexes in aqueous solution.

    PubMed

    Lienke, A; Klatt, G; Robinson, D J; Koch, K R; Naidoo, K J

    2001-05-01

    We construct force fields suited for the study of three platinum group metals (PGM) as chloranions in aqueous solution from quantum chemical computations and report experimental data. Density functional theory (DFT) using the local density approximation (LDA), as well as extended basis sets that incorporate relativistic corrections for the transition metal atoms, has been used to obtain equilibrium geometries, harmonic vibrational frequencies, and atomic charges for the complexes. We found that DFT calculations of [PtCl(6)](2-).3H(2)O, [PdCl(4)](2-).2H(2)O, and [RhCl(6)](3-).3H(2)O water clusters compared well with molecular mechanics (MM) calculations using the specific force field developed here. The force field performed equally well in condensed phase simulations. A 500 ps molecular dynamics (MD) simulation of [PtCl(6)](2-) in water was used to study the structure of the solvation shell around the anion. The resulting data were compared to an experimental radial distribution function derived from X-ray diffraction experiments. We found the calculated pair correlation functions (PCF) for hexachloroplatinate to be in good agreement with experiment and were able to use the simulation results to identify and resolve two water-anion peaks in the experimental spectrum. PMID:11327912

  19. Platinum group minerals in podiform chromitites of the Bou Azzer ophiolite, Anti Atlas, Central Morocco

    NASA Astrophysics Data System (ADS)

    El Ghorfi, M.; Melcher, F.; Oberthür, T.; Boukhari, A. E.; Maacha, L.; Maddi, A.; Mhaili, M.

    2008-01-01

    The Neoproterozoic Bou Azzer ophiolite complex hosts numerous, small lenticular bodies of massive and disseminated chromite. Metallurgical-grade high-Mg and high-Cr spinels (cores with 48-62 wt% Cr2O3) reveal complex alteration patterns of successive Cr and Mn enrichment and loss of Al towards the rims, while the Mg# ratios [(Mg/(Mg + Fe2+)] remain almost constant. Concentration patterns of platinum-group elements are typical for ophiolitic chromitite poor in sulfides, with predominance of the IPGE, variable Rh, and low Pt and Pd. The most abundant platinum-group mineral is Rh-bearing laurite that occurs either included in spinel or in silicate matrix, whereas Os-Ir-Ru alloy is always included in spinel. Laurite inclusions reveal complex intergrowth textures with Rh-Ru-Pt rich alloy, and with Rh-rich sulfide. Most laurites display trends to sulfur-poor compositions leading to local formation of very fine-grained Ru-Os-Ir alloy phases. Ni-Co-Fe sulfides, arsenides and sulfarsenides devoid of PGE are associated with the alteration of chromite. Textural position and chemical composition of the base metal inclusions, as well as comparison of alteration features between chromite and accessory chromian spinel in the Co-Ni-As ores of the Bou Azzer ophiolite indicate a close connection. It is suggested that hydrothermal fluids percolated through the marginal zones of the ophiolite belt during greenschist facies metamorphism and deposited Ni-Co-Fe arsenides, sulfarsenides and minor sulfides as accessories within altered chromitites, and also in structurally favourable zones as Ni-Co-As ores.

  20. Trace element accumulation in aquatic plants: a literature review

    SciTech Connect

    Ganje, T.J.; Elseewi, A.A.; Page, A.L.

    1988-01-01

    Trace elements in sediments and its overlying waters are important constituents of an aquatic plant ecosystem. This review was undertaken to evaluate trace element accumulation in aquatic plants and ascertain to what extent sediment and its overlying waters play in trace element accumulation by aquatic plant species. Aquatic vascular plants tend to accumulate trace elements in relation to the trace element concentration of the water body and sediment in which they are grown and the extent of exposure to the water body. Trace element composition of bryophytes and algae is also closely related to composition of their aquatic environment. It is increasingly apparent that sediments and overlying waters alter the bioavailability of trace elements to aquatic plants in both natural and artificial water bodies, particularly where industrial and agricultural waters are discharged into waterways.

  1. The Bioaccumulation and Toxicity of Platinum Group Metals in Developing Chick Embryos

    NASA Astrophysics Data System (ADS)

    Pavel, Ioana; Monahan, Jennifer; Markopoulos, Marjorie; Gagnon, Zofia; Nejame, Britney; Cawley, Jacob; Reens, David

    2008-10-01

    Recent studies showed that platinum group metals (PGMs) such as Pt, Pd, and Rh from automobile catalytic converters, can accumulate in the soft tissues of a variety of living organisms. However, the effects of PGMs on bone and organs development of animals are not clearly understood. To examine these aspects, developing chick embryos were injected with 0.1, 1.0, 5, or 10 ppm solutions of Pt, Rh, Pd, or with a PGMs mixture. 1) Pathological Changes: were observed for all PGM treatments above 1 ppm. Bone Cells Assesment: Chondrocyte cells in thibiotarsus showed decreased diameter and length. 2) PGMs Accumulation in Tissues: was quantified by GFAAS spectrometry on finely ground tissue powder. 3) Bone Demineralization: was detected by micro-Raman spectroscopy imaging on paraffin embedded bone sections. 4) DNA Damage in Cells: was determined by using a Comet assay and fluorescence spectroscopy. Oxidative Damage in Tissues: was analyzed using a glutathione peroxidase assay. The overall results indicated that PGMs presence in our environment raises concerns about their long-term health effects on all organisms.

  2. X-ray characterization of platinum group metal catalysts

    NASA Astrophysics Data System (ADS)

    Peterson, Eric J.

    Platinum group metals (PGMs) are used extensively as catalysts, employed in several sectors of the world energy economy. Fuel cells employing PGM catalysts show promise as power sources in the proposed hydrogen economy, using alcohols as hydrogen storage media. Currently, the most economically important application for PGMs is for the mitigation of emissions from internal combustion engines via catalytic converters. In all applications, efficient use of these expensive metals to fabricate robust catalysts is of the utmost importance. Understanding the catalyst structure/property relationship is the key to the improvement of existing catalysts and the discovery of new catalysts. For example, catalyst particle size can have profound effects on catalyst activity, as in the case of gold nanoparticles. Catalyst particle size control and stability is also important for the efficient use of PGM metals and catalyst deactivation prevention. The challenge is to identify and characterize structural features and determine if and how these features may relate to catalytic properties. The ultimate goal is to simultaneously measure catalyst structural characteristics and catalytic properties under operando conditions, unambiguously establishing the structure/property link. X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are important techniques used for the characterization of PGM catalysts. Microstructural information such as crystallite size, as small as ~ 1 nm, and microstrain can be obtained from Bragg diffraction peak shapes in X-ray diffraction patterns, and long range crystal structure information is found in the intensities and positions of these peaks. In contrast, X-ray absorption spectroscopy provides information about the chemical state and local structure of selected atoms. From the average nearest neighbor coordination numbers, crystallite sizes can also be inferred, with particularly high sensitivity in the sub-nm size range. Electron microscopy

  3. The platinum group metals in Younger Dryas Horizons are terrestrial

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Wikes, E.; Kennett, J.; West, A.; Sharma, M.

    2009-12-01

    The Younger Dryas (YD) event, which began 12,900 years ago, was a period of abrupt and rapid cooling in the Northern Hemisphere whose primary cause remains unclear. The prevalent postulated mechanism is a temporary shutdown of the thermohaline circulation following the breakup of an ice dam in North America. Firestone et al. (2007) proposed that the cooling was triggered by multiple cometary airbursts and/or impacts that engendered enormous environmental changes and disrupted the thermohaline circulation. The evidence in support for this hypothesis is a black layer in North America and in Europe marking the YD boundary containing charcoal, soot, carbon spherules and glass-like carbon suggesting extensive and intense forest fires. This layer is also enriched in magnetic grains high in iridium, magnetic microspherules, fullerenes containing extraterrestrial He-3, and nanodiamonds. Whereas the nanodiamonds could be produced in an impact or arrive with the impactor, the cometary burst/impact hypothesis remains highly controversial as the YD horizon lacks important impact markers such as craters, breccias, tektites and shocked minerals. Firestone et al. (2007) contend that bulk of Ir found at the YD boundary is associated with magnetic grains. The key issue is whether this Ir is meteorite derived. We used Ir and Os concentrations and Os isotopes to investigate the provenance of the platinum group metals in the YD horizon. The bulk sediment samples from a number of North American YD sites (Blackwater Draw, Murray Springs, Gainey, Sheriden Cave, and Myrtle Beach) and a site in Europe (Lommel) do not show any traces of meteorite derived Os and Ir. The [Os] = 2 to 45 pg/g in these sediments and the 187Os/188Os ratios are similar to the upper continental crustal values (~1.3), much higher than those in meteorites (0.13). Higher [Os] is observed in Blackwater Draw (= 194 pg/g). However, the Os/Ir ratio in Blackwater Draw is 5 (not 1 as expected for a meteorite) and 187Os/188

  4. Accumulation of trace elements by Pistia stratiotes: implications for phytoremediation.

    PubMed

    Odjegba, V J; Fasidi, I O

    2004-10-01

    The toxicity of eight potentially toxic trace elements (Ag, Cd, Cr, Cu, Hg, Ni, Pb and Zn) to Pistia stratiotes was examined to determine if this plant showed sufficient tolerance and metal accumulation to be used to phytoremediate waste water and/or natural water bodies polluted with these heavy metals. Young plants of equal size were grown hydroponically and amended with 0, 0.1, 0.3, 0.5, 1.0, 3.0 and 5.0 mM of each heavy metal individually for 21 days. Root elongation as well as emergence of new roots decreased significantly with increase in metal concentrations. The plant had the lowest and the highest tolerance indices for Hg and Zn respectively. The study indicated reduction in the rate of leaf expansion relative to metal type, their concentrations and the duration of exposure. A significant reduction in biomass production was observed in metal treated plants compared with the control plants. The relative growth rate of P. stratiotes was retarded by heavy metals under study. All trace elements accumulated to higher concentrations in root tissue rather than in shoot. Trace element accumulation in tissues and the bioconcentration factors were proportional to the initial concentration of individual metals in the growth medium and the duration of exposure. In terms of trace element removal, P. stratiotes presented differential accumulation and tolerance levels for different metals at similar treatment conditions. The implications of these results for phytoremediation are discussed. PMID:15673213

  5. C-H Oxidation by Platinum Group Metal Oxo or Peroxo Species

    SciTech Connect

    Zhou, Meng; Crabtree, Robert H

    2011-01-01

    While C–H oxidation by ruthenium oxo compounds has been broadly applied in organic synthesis, examples of C–H oxidation by metal oxo complexes from the rest of the platinum group are still rare. We survey the preparation and reactivity of these late-transition metal oxo and peroxo complexes in this tutorial review.

  6. No Accumulation of Transposable Elements in Asexual Arthropods.

    PubMed

    Bast, Jens; Schaefer, Ina; Schwander, Tanja; Maraun, Mark; Scheu, Stefan; Kraaijeveld, Ken

    2016-03-01

    Transposable elements (TEs) and other repetitive DNA can accumulate in the absence of recombination, a process contributing to the degeneration of Y-chromosomes and other nonrecombining genome portions. A similar accumulation of repetitive DNA is expected for asexually reproducing species, given their entire genome is effectively nonrecombining. We tested this expectation by comparing the whole-genome TE loads of five asexual arthropod lineages and their sexual relatives, including asexual and sexual lineages of crustaceans (Daphnia water fleas), insects (Leptopilina wasps), and mites (Oribatida). Surprisingly, there was no evidence for increased TE load in genomes of asexual as compared to sexual lineages, neither for all classes of repetitive elements combined nor for specific TE families. Our study therefore suggests that nonrecombining genomes do not accumulate TEs like nonrecombining genomic regions of sexual lineages. Even if a slight but undetected increase of TEs were caused by asexual reproduction, it appears to be negligible compared to variance between species caused by processes unrelated to reproductive mode. It remains to be determined if molecular mechanisms underlying genome regulation in asexuals hamper TE activity. Alternatively, the differences in TE dynamics between nonrecombining genomes in asexual lineages versus nonrecombining genome portions in sexual species might stem from selection for benign TEs in asexual lineages because of the lack of genetic conflict between TEs and their hosts and/or because asexual lineages may only arise from sexual ancestors with particularly low TE loads. PMID:26560353

  7. No Accumulation of Transposable Elements in Asexual Arthropods

    PubMed Central

    Bast, Jens; Schaefer, Ina; Schwander, Tanja; Maraun, Mark; Scheu, Stefan; Kraaijeveld, Ken

    2016-01-01

    Transposable elements (TEs) and other repetitive DNA can accumulate in the absence of recombination, a process contributing to the degeneration of Y-chromosomes and other nonrecombining genome portions. A similar accumulation of repetitive DNA is expected for asexually reproducing species, given their entire genome is effectively nonrecombining. We tested this expectation by comparing the whole-genome TE loads of five asexual arthropod lineages and their sexual relatives, including asexual and sexual lineages of crustaceans (Daphnia water fleas), insects (Leptopilina wasps), and mites (Oribatida). Surprisingly, there was no evidence for increased TE load in genomes of asexual as compared to sexual lineages, neither for all classes of repetitive elements combined nor for specific TE families. Our study therefore suggests that nonrecombining genomes do not accumulate TEs like nonrecombining genomic regions of sexual lineages. Even if a slight but undetected increase of TEs were caused by asexual reproduction, it appears to be negligible compared to variance between species caused by processes unrelated to reproductive mode. It remains to be determined if molecular mechanisms underlying genome regulation in asexuals hamper TE activity. Alternatively, the differences in TE dynamics between nonrecombining genomes in asexual lineages versus nonrecombining genome portions in sexual species might stem from selection for benign TEs in asexual lineages because of the lack of genetic conflict between TEs and their hosts and/or because asexual lineages may only arise from sexual ancestors with particularly low TE loads. PMID:26560353

  8. Germanium and Rare Earth Element accumulation in woody bioenergy crops

    NASA Astrophysics Data System (ADS)

    Hentschel, Werner

    2016-04-01

    Germanium and REEs are strategic elements that are used for high tech devices and engineered systems, however these elements are hardly concentrated into mineable ore deposits. Since these elements occur widely dispersed in the earth crust with concentrations of several mgṡkg‑1 (Ge 1.6 mgṡkg‑1, Nd 25 mgṡkg‑1) a new possibility to gain these elements could be phytomining, a technique that uses plants to extract elements from soils via their roots. Since knowledge about accumulating plant species is quite limited we conducted research on the concentrations of strategic elements in wood and leaves of fast growing tree species (Salix spec., Populus spec., Betula pendula, Alnus glutinosa, Fraxinus excelsior, Acer pseudoplatanus). In total 35 study sites were selected in the mining affected area around Freiberg (Saxony, Germany), differing in their species composition and degree of contamination with toxic trace metals (Pb, As, Cd). On each site plant tissues (wood and leaves, respectively) of different species were sampled. In addition soil samples were taken from a soil depth of 0 - 30 cm and 30 - 60 cm. The aim of our work was to investigate correlations between the concentrations of the target elements in plant tissues and soil characteristics like pH, texture, nutrients and concentrations in six operationally defined soil fractions (mobile, acid soluble, oxidizable, amorphic oxides, crystalline oxides, residual or siliceous). Concentrations of elements in soil extracts and plant tissues were measured with ICP-MS. The element Nd was selected as representative for the group of REEs, since this element showed a high correlation with the concentrations of the other REE We found that the concentration of Nd in the leaves (0.31 mgṡkg‑1Nd) were several times higher than in herbaceous species (0.05 mgṡkg‑1 Nd). The concentration of Ge in leaves were ten times lower than that of Nd whereas in herbaceous species Nd and Ge were in equal magnitude. Within

  9. Relevance and analysis of traffic related platinum group metals (Pt, Pd, Rh) in the aquatic biosphere, with emphasis on palladium.

    PubMed

    Sures, Bernd; Zimmermann, Sonja; Messerschmidt, Jürgen; von Bohlen, Alex

    2002-10-01

    Following the introduction of automobile catalysts in the middle of the Eighties in Germany there is an increasing emission of the platinum-group-metals (PGM) platinum (Pt), palladium (Pd) and rhodium (Rh). Still, it remains unclear if these metals are bioavailable for aquatic animals and to which extent they accumulate in the aquatic biosphere. Zebra mussels (Dreissena polymorpha) were maintained in water containing road dust at a concentration of 1 kg/10 l. Following an exposure period of 26 weeks, soft tissues of the mussels were analysed applying adsorptive cathodic stripping voltammetry (ACSV) for the determination of Pt and Rh and total-reflection X-ray fluorescence analysis after co-precipitation of Pd with mercury. This experiment revealed for the first time that all the three catalyst emitted metals were accumulated by mussels. The bioaccumulation increased in the following manner: Rh < Pt < Pd. Thus, the application of sentinel organisms in combination with modern trace analytical procedures in environmental impact studies does allow an assessment of the distribution and the degree of bioaccumulation of PGM in the environment, which is highly appreciated. PMID:12463686

  10. Lipid solubility of the platinum group metals Pt, Pd and Rh in dependence on the presence of complexing agents.

    PubMed

    Zimmermann, Sonja; Menzel, Christoph M; Stüben, Doris; Taraschewski, Horst; Sures, Bernd

    2003-01-01

    Investigations on the bioaccumulation of the platinum group metals (PGM) Pt, Pd and Rh in aquatic organisms are of growing interest in environmental research due to the increasing emission of these metals by motor vehicles with catalytic converters. Until now, nothing is known about the possible influence of complexing agents on the bioaccumulation capacity of these precious metals. According to the partition coefficient between 1-octanol and water (POW) as a measure of bioaccumulation, in this study a simple shaking method was performed in order to investigate the effects of different complexing agents (-methionine, thio urea, EDTA, humic substances, bile compounds) on the octanol solubility of the PGM. The results demonstrated a significant influence of all agents used. -Methionine and thio urea decreased the lipid solubility. In contrast, the presence of EDTA, humic substances and especially bile caused a higher transfer of metals in the octanol phase. For most complexing agents tested, the transfer of Pd to the lipid phase was significantly higher compared with Rh and Pt, except for bile acid where the highest octanol solubility was found for Pt. Recent experimental results on PGM accumulation in zebra mussels confirm a high bioaccumulation of Pd which could be predicted from the lipid solubility. PMID:12683977

  11. Mineral potential for nickel, copper, platinum group elements(PGE), and chromium deposits hosted in ultramafic rocks in the Islamic Republic of Mauritania (phase V, deliverable 67): Chapter G in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

    USGS Publications Warehouse

    Taylor, Cliff D.; Marsh, Erin; Anderson, Eric D.

    2015-01-01

    PRISM-I summary documents mention the presence of mafic-ultramafic igneous intrusive rocks in several areas of Mauritania and a number of chromium (Cr) and copper-nickel (Cu-Ni (±Co, Au)) occurrences associated with them. Permissive geologic settings generally include greenstone belts of any age, layered mafic-ultramafic and unlayered gabbro-anorthosite intrusive complexes in cratonic settings, ophiolite complexes, flood basalt provinces, and fluid-rich shear zones cutting accumulations of mafic-ultramafic rocks. Regions of Mauritania having these characteristics that are discussed in PRISM-I texts include the Mesoarchean greenstone belts of the TasiastTijirit terrane in the southwestern Rgueïbat Shield, two separate layered ultramafic complexes in the Amsaga Complex west of Atar, serpentinized metadunites in Mesoarchean rocks of the Rgueïbat Shield in the Zednes map sheet, several lateritized annular mafic-ultramafic complexes in the Paleoproterozoic northwestern portion of the Rgueïbat Shield, and the serpentinized ophiolitic segments of the Gorgol Noir Complex in the axial portion of the southern Mauritanides. Bureau de Recherches Géologiques et Minières (BRGM) work in the “Extreme Sud” zone also suggests that small copper occurrences associated with the extensive Jurassic microgabbroic intrusive rocks in the Taoudeni Basin of southeastern Mauritania could have potential for magmatic Cu-Ni (PGE, Co, Au) sulfide mineralization. Similarly, Jurassic mafic intrusive rocks in the northeastern Taoudeni Basin may be permissive. Known magmatic Cu-Ni deposits of these types in Mauritania are few in number and some uncertainty exists as to the nature of several of the more important ones.

  12. Permissive tracts for nickel, copper, platinum group elements (PGE), and chromium deposits of Mauritania (phase V, deliverable 66): Chapter G1 in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

    USGS Publications Warehouse

    Taylor, Cliff D.; Horton, John D.

    2012-01-01

    This report contains the USGS results of the PRISM-II Mauritania Minerals Project and is presented in cooperation with the Ministry of Petroleum, Energy, and Mines of the Islamic Republic of Mauritania. The Report is composed of separate chapters consisting of multidisciplinary interpretive reports with accompanying plates on the geology, structure, geochronology, geophysics, hydrogeology, geochemistry, remote sensing (Landsat TM and ASTER), and SRTM and ASTER digital elevation models of Mauritania. The syntheses of these multidisciplinary data formed the basis for additional chapters containing interpretive reports on 12 different commodities and deposit types known to occur in Mauritania, accompanied by countrywide mineral resource potential maps of each commodity/deposit type. The commodities and deposit types represented include: (1) Ni, Cu, PGE, and Cr deposits hosted in ultramafic rocks; (2) orogenic, Carlin-like, and epithermal gold deposits; (3) polymetallic Pb-Zn-Cu vein deposits; (4) sediment-hosted Pb-Zn-Ag deposits of the SEDEX and Mississippi Valley-type; (5) sediment-hosted copper deposits; ( 6) volcanogenic massive sulfide deposits; (7) iron oxide copper-gold deposits; (8) uranium deposits; (9) Algoma-, Superior-, and oolitic-type iron deposits; (10) shoreline Ti-Zr placer deposits; (11) incompatible element deposits hosted in pegmatites, alkaline rocks, and carbonatites, and; (12) industrial mineral deposits. Additional chapters include the Mauritanian National Mineral Deposits Database are accompanied by an explanatory text and the Mauritania Minerals Project GIS that contains all of the interpretive layers created by USGS scientists. Raw data not in the public domain may be obtained from the Ministry of Petroleum, Energy, and Mines in Nouakchott, Mauritania.

  13. Chemical Forms and Distribution of Platinum Group Metals and Technetium During Spent Fuel Reprocessing

    SciTech Connect

    Pokhitonov, Y.

    2007-07-01

    Amongst the fission products present in spent nuclear fuel of Nuclear Power Plants there are considerable quantities of platinum group metals (PGMs): ruthenium, rhodium and palladium. At the same time there are considerable amounts of technetium in the spent fuel, the problem of its removal at radiochemical plants being in operation encountering serious difficulties. Increased interest in this radionuclides is due not only to its rather large yield, but to higher mobility in the environment as well. However, the peculiarities of technetium chemistry in nitric acid solutions create certain problems when trying to separate it as a single product in the course of NPP's spent fuel reprocessing. The object of this work was to conduct a comprehensive analysis of platinum group metals and technetium behavior at various stages of spent fuel reprocessing and to seek the decisions which could make it possible to separate its as a single product. The paper will report data on platinum metals (PGM) and technetium distribution in spent fuel reprocessing products. The description of various techniques for palladium recovery from differing in composition radioactive solutions arising from reprocessing is given. (authors)

  14. Platinum group metal particles aggregation in nuclear glass melts under the effect of temperature

    NASA Astrophysics Data System (ADS)

    Hanotin, Caroline; Puig, Jean; Neyret, Muriel; Marchal, Philippe

    2016-08-01

    The viscosity of simulated high level radioactive waste glasses containing platinum group metal particles is studied over a wide range of shear stress, as a function of the particles content and the temperature, thanks to a stress imposed rheometer, coupled to a high-temperature furnace. The system shows a very shear thinning behavior. At high shear rate, the system behaves as a suspension of small clusters and individual particles and is entirely controlled by the viscosity of the glass matrix as classical suspensions. At low shear rate, above a certain fraction in platinum group metal particles, the apparition of macroscopic aggregates made up of chains of RuO2 particles separated by thin layers of glass matrix strongly influences the viscosity of the nuclear glass and leads, in particular, to the apparition of yield stress and thixotropic effects. The maximum size of these clusters as well as their effective volume fraction have been estimated by a balance between Van der Waals attractive forces and hydrodynamic forces due to shear flow. We showed experimentally and theoretically that this aggregation phenomenon is favored by an increase of the temperature, owing to the viscosity decrease of the glass matrix, leading to an unusual increase of the suspension viscosity.

  15. Versatile Oxidation Methods for Organic and Inorganic Substrates Catalyzed by Platinum-Group Metals on Carbons.

    PubMed

    Sawama, Yoshinari; Asai, Shota; Monguchi, Yasunari; Sajiki, Hironao

    2016-02-01

    Platinum-group metals on activated carbon catalysts, represented by Pd/C, Ru/C, Rh/C, etc., are widely utilized to accomplish green and sustainable organic reactions due to their favorable features, such as easy handling, recoverability, and reusability. The efficient oxidation methods of various organic compounds using heterogeneous platinum-group metals on carbons with or without added oxidants are summarized in this Personal Account. The oxidation of internal alkynes into diketones was effectively catalyzed by Pd/C in the presence of dimethyl sulfoxide and molecular oxygen or pyridine N-oxide. The Pd/C-catalyzed mild combustion of gaseous hydrogen with molecular oxygen provided hydrogen peroxide, which could be directly utilized for the oxidation of sulfide derivatives into sulfoxides. Furthermore, the Ru/C-catalyzed aerobic oxidation of primary and secondary alcohols gave the corresponding aldehydes and ketones, respectively. On the other hand, the dehydrogenative oxidation of secondary alcohols into ketones was achieved using Rh/C in water, and primary alcohols were effectively dehydrogenated by Pd/C in water under mildly reduced pressure to produce carboxylic acids. PMID:26666634

  16. Platinum-group minerals in the Limoeiro Ni-Cu-(PGE) sulfide deposit, Brazil: the effect of magmatic and upper amphibolite to granulite metamorphic processes on PGM formation

    NASA Astrophysics Data System (ADS)

    Mota-e-Silva, J.; Prichard, H. M.; Filho, C. F. Ferreira; Fisher, P. C.; McDonald, I.

    2015-12-01

    The Limoeiro Ni-Cu-(platinum-group elements (PGE)) deposit is a recent discovery associated with an igneous tubular conduit system in northeastern Brazil. Representative ores from the deposit have been used for platinum-group minerals (PGM) identification and for PGE in base metal sulfides (BMS) quantification. Ninety-eighty percent of the PGM in the massive sulfide ores is homogeneous Pt-Ni-Bi-bearing merenskyite (PdTe2) enclosed primarily by pyrrhotite, suggesting that it is formed by exsolution from monosulfide solid solution (MSS). Merenskyite gradually but systematically becomes poorer in Pt and Ni with increasing fractionation, which is interpreted to reflect a transition to a more evolved sulfide liquid that segregated in the eastern parts of the intrusion. In massive sulfide ores, merenskyite forms unusually large (up to 5000 μm2) euhedral grains, commonly in contact with spherical silicate inclusions. BMS hosts 12-16 % of the Pd, with the remainder hosted by PGM, which is interpreted to indicate that merenskyite recrystallized from a PGE-bearing bismuthotelluride metamorphic melt formed during high-grade metamorphism. Sperrylite (PtAs2) is the second most abundant PGM (18 % of PGM in disseminated ore) and in contrast to merenskyite occurs mainly as very small (median of 25 μm2) inclusions in high-temperature silicates and oxides, interpreted to have crystallized at high temperatures directly from sulfide blebs that formed and were transported within the Limoeiro magma conduit.

  17. Platinum-Group Elements in Basalts Derived From the Icelandic Mantle Plume -Past and Present.

    NASA Astrophysics Data System (ADS)

    Momme, P.; Oskarsson, N.; Gronvold, K.; Tegner, C.; Brooks, K.; Keays, R.

    2001-12-01

    Paleogene basalts ( ~55Ma) derived from the ancestral Iceland mantle plume and extruded during continental rifting are exposed along the Blosseville Kyst in central East Greenland. These basalts comprise three intercalated series, viz: a low-Ti, high-Ti and a very high-Ti series. The two Ti-rich series are interpreted to represent continental flood basalts formed by low degrees of partial melting (degree of melting F=3-9%) while the low-Ti series are believed to have formed by higher degrees of partial melting (F:15-25%). All three of the East Greenland basalt series are enriched in the PGE, relative to normal MORB. During differentiation of the low-Ti series, Pd increase from 11 to 24 ppb whereas Pt and Ir decrease from 12 and 0.6 ppb to 3 and <0.05 ppb respectively. The primitive basalts (molar Mg#60) of the dominant high-Ti series contain ~6-10 ppb Pd, ~7-10 ppb Pt and ~0.2 ppb Ir whereas the most evolved basalts (Mg#43) contain 25 ppb Pd, 5 ppb Pt and <0.05 ppb Ir. The PGE-rich nature of these basalts is surprising because low degree partial melts are generally S-saturated and hence strongly depleted in the PGE (cf, Keays, 1995). However, our data indicates that all of the East Greenland magmas were S-undersaturated and as they underwent differentiation, Pd behaved incompatibly while Ir and Pt behaved compatibly. Primitive Holocene Icelandic olivine tholeiites contain 120 ppm Cu, 6 ppb Pd, 4 ppb Pt and 0.2 ppb Ir while their picritic counterparts contain 74 ppm Cu, 17 ppb Pd, 7 ppb Pt and 0.3 ppb Ir. Both the olivine tholeiites and the picrites are believed to have formed by high degrees of partial melting (15-25%) which would have exhausted all of the sulphides in the mantle source region and produced S-undersaturated magmas. In Icelandic samples with 10-14wt% MgO, Cu and the PGEs vary systematically between the primitive picrite and olivine tholeiite compositions given above i.e there is an inverse correlation between Cu and the PGEs. This is best explained by mixing between parental olivine tholeiite and picrite magmas. The low Cu/Pd ratio in the most primitive picrite probably reflect derivation from a depleted mantle where Cu was less efficiently retained in sulphides compared to Pd during previous melt extraction episodes. Whithin the analysed suite of olivine tholeiites, Ir decreases from 0.15 to 0.06 ppb, Pd increases from ~6 to ~15 ppb and Pt/Pd ratio decreases from 0.8-0.2 during differentiation (7-4wt% MgO); these variations provide further evidence that the olivine tholeiite magmas remained S-undersaturated throughout their differentiation. To summarize, (1) Continental flood basalts and low-Ti tholeiites in the Paleogene East Greenland flood basalt sequence, as well as Holocene Icelandic olivine tholeiites are PGE-rich relative to normal MORB. (2) Their PGE-contents vary as a function of S-undersaturated differentiation. (3) Cu-PGE variations in Icelandic samples with 10-14 wt% MgO suggest that they represent mixtures between distinct tholeiitic (Cu/Pd: 20000) and depleted picritic (Cu/Pd: 4400) parental liquids. Reference: Keays RR (1995) The role of komatiitic magmatism and S-saturation in the formation of ore deposits. Lithos 34:1-18.

  18. Polyhydrides of Platinum Group Metals: Nonclassical Interactions and σ-Bond Activation Reactions.

    PubMed

    Esteruelas, Miguel A; López, Ana M; Oliván, Montserrat

    2016-08-10

    The preparation, structure, dynamic behavior in solution, and reactivity of polyhydride complexes of platinum group metals, described during the last three decades, are contextualized from both organometallic and coordination chemistry points of view. These compounds, which contain dihydrogen, elongated dihydrogen, compressed dihydride, and classical dihydride ligands promote the activation of B-H, C-H, Si-H, N-H, O-H, C-C, C-N, and C-F, among other σ-bonds. In this review, it is shown that, unlike other more mature areas, the chemistry of polyhydrides offers new exciting conceptual challenges and at the same time the possibility of interacting with other fields including the conversion and storage of regenerative energy, organic synthetic chemistry, drug design, and material science. This wide range of possible interactions foresees promising advances in the near future. PMID:27268136

  19. Gas-phase catalysis by platinum-group metals—past, present, and future

    NASA Astrophysics Data System (ADS)

    Golunski, Stan

    2001-10-01

    Platinum-group metals (PGMs) are the chosen catalysts for many modern gas-phase processes, in both the clean production and the clean destruction of chemicals. These metals are inherently stable, even when highly dispersed, and yet they have enough surface reactivity to activate a range of different molecular species. Traditionally used to catalyze single reactions under steady-state conditions, they are increasingly being applied to more complex processes. Their ability to catalyze two energetically opposing reactions means that energy-consuming and energy-wasting processes can be combined in a single efficient reactor. Furthermore, the electronic properties of PGMs can be exploited in M-MO composites, in which the metal does not provide the active sites, but modifies the solid-state chemistry of the metal oxide to make it catalytically productive.

  20. Noble metals in mid-ocean ridge volcanism: A significant fractionation of gold with respect to platinum group metals

    NASA Technical Reports Server (NTRS)

    Crocket, James H.

    1988-01-01

    Hydrothermal precipitates, black smoker particulate, and massive sulphide dredge samples from the Explorer Ridge on the Juan de Fuca Plate and the TAG hydrothermal area on the Mid-Atlantic Ridge were analyzed for selected noble metals including Au, Ir and Pd by radiochemical neutron activation analysis. The preliminary results indicate that gold contents may reach the ppm range although values in the neighborhood of 100 to 200 ppb are more typical. The platinum group elements (PGE) represented by Ir and Pd are typically less than 0.02 ppb and less than 2 ppb respectively. These abundances represent a significant enrichment of gold relative to the PGE in comparison with average noble metal abundances in mid-ocean ridge basalts (MORB). A partial explanation of this distinctive fractionation can be found in the concepts of sulfur-saturation of basic magma in mid-ocean ridge (MOR) settings, and the origin of MOR hydrothermal fluids. Experimental and petrological data suggest that MORBs are sulfur-saturated at the time of magma generation and that an immiscible sulfide component remains in the mantle residue. Hence, MORBs are noble metal-poor, particularly with respect to PGE. Consequently, black smoker fluids can be expected to reflect the low Ir and Pd contents of the rock column. The average Au content of MORB is 1.3 ppb, and so the rock column is not significantly enriched in Au. The generation of fluids which precipitate solids with 200 ppb Au is apparently dependent on highly efficient fluid chemistry to mobilize Au from the rock column, high Au solubility in seawater hydrothermal fluids and efficient precipitation mechanisms to coprecipitate Au on Fe, Zn and Cu sulfides. Significant differences in these parameters appear to be the ultimate cause of the strong Au-PGE fractionation in the MOR setting. It does not appear from the current data base that MOR hydrothermal fluids are significant contributors to the Ir enrichment seen in Cretaceous-Tertiary boundary

  1. Origin of platinum-group mineral assemblages in a mantle tectonite at Unst deduced from mineral chemistry and osmium isotopes

    NASA Astrophysics Data System (ADS)

    Badanina, Inna Yu.; Lord, Richard A.; Malitch, Kreshimir N.; Meisel, Thomas C.

    2013-04-01

    assemblage is likely to reflect processes such as in-situ serpentinisation, alteration during emplacement or regional greenschist metamorphism. Whole-rock platinum-group element (PGE) concentrations give negatively sloped chondrite-normalized PGE patterns, typical of podiform chromitite, where refractory PGE (Os, Ir and Ru) prevail over less refractory PGE (Rh, Pt and Pd). The osmium isotope results identify similarly 'unradiogenic' 187Os/188Os values for 'primary' and 'secondary' PGM assemblages (with mean 187Os/188Os values of 0.12419 and 0.12464, respectively), being within uncertainty of the chromitite composition (0.1240±0.0006). This implies that the whole-rock Os isotope budget is largely controlled by laurite-dominant assemblages, supporting the conclusion that the 'secondary' PGM assemblage inherited the subchondritic osmium isotope signature of the 'primary' PGM. No evidence for other source contributions during later thermal events has been observed. The Os-isotope data provide further support for an Enstatite Chondrite Reservoir model for the convective upper mantle as defined by Walker et al. (2002) and are consistent with origin of the complex as a Caledonian ophiolite formed in a supra-subduction zone. This study was supported by Russian Foundation for Basic Research (grant 12-05-01166-a to IYuB) and the Uralian Division of Russian Academy of Sciences (project No 12-P-5-1020). References: Andrews, D.R.A., Brenan, J.M. (2002) Phase-equilibrium constraints on the magmatic origin of laurite and Os-Ir alloy. Can. Mineral. 40, 1705-1716. Walker, R.J., Prichard, H.M., Ishiwatari, A., Pimentel, M. (2002) The osmium isotopic composition of convecting upper mantle deduced from ophiolite chromites. Geochim. Cosmochim. Acta 66, 329-345.

  2. Platinum-group minerals in the LG and MG chromitites of the eastern Bushveld Complex, South Africa

    NASA Astrophysics Data System (ADS)

    Oberthür, Thomas; Junge, Malte; Rudashevsky, Nikolay; de Meyer, Eveline; Gutter, Paul

    2016-01-01

    The chromitites of the Bushveld Complex in South Africa contain vast resources of platinum-group elements (PGE); however, except for the economic upper group (UG)-2 chromitite seam, information on the distribution of the PGE in the ores and on the mineralogical nature, assemblages, and proportions of platinum-group minerals (PGM) is essentially missing. In the present geochemical and mineralogical study, PGE concentrates originating from the lower group (LG)-6 and middle group (MG)-1/2 chromitites were investigated with the intention to fill this gap of knowledge. Chondrite-normalized PGE patterns of bulk rock and concentrates are characterized by a positive slope from Os to Rh, a slight drop to Pt, and an increase to Pd again. The pronounced similarities of the PGE patterns indicate similar primary processes of PGE concentration in the chromitites, namely "sulfide control" of the PGE mineralization, i.e., co-precipitation of chromite and sulfide. Further, the primary control of PGE concentration in chromitites appears to be dual in character: (i) base-level concentrations of IPGE (up to ˜500 ppb) hosted within chromite and (ii) co-precipitation of chromite and sulfide, the latter containing virtually the entire remaining PGE budget. Sulfides (chalcopyrite, pentlandite, and pyrite; pyrrhotite is largely missing) are scarce within the chromitites and occur mainly interstitial to chromite grains. Pd and Rh contents in pentlandite are low and erratic. Essentially, the whole PGE inventory of the ores occurs in the form of discrete PGM. The PGM are almost always associated with sulfides. The dominant PGM are various Pt-Pd-Rh sulfides (cooperite/braggite [(Pt,Pd)S] and malanite/cuprorhodsite [CuPt2S4]/[CuRh2S4]), laurite [RuS2], the main carrier of the IPGE (Os, Ir, Ru), sulfarsenides [(Rh,Pt,Ir)AsS], sperrylite [PtAs2], Pt-Fe alloys, and a large variety of mainly Pd-rich PGM. The LG and MG chromitites have many characteristics in common and define a general, "typical

  3. Electrochemical metallization switching with a platinum group metal in different oxides

    NASA Astrophysics Data System (ADS)

    Wang, Zhongrui; Jiang, Hao; Hyung Jang, Moon; Lin, Peng; Ribbe, Alexander; Xia, Qiangfei; Yang, J. Joshua

    2016-07-01

    In a normal electrochemical metallization (ECM) switch, electrochemically active metals, such as Ag and Cu are used to provide mobile ions for the conducting filament. In both ECM and valence change memory (VCM) devices, platinum group metals, such as Pt and Pd, are typically used as the counter electrode and assumed to be chemically and physically inert. In this study, we explore whether the so-called inert metal itself can form a conducting filament and result in repeatable resistance switching. Pd and different oxide host matrices are used for this purpose. We have observed that the transport of oxygen anions dominates over Pd metal cations in ALD deposited AlOx and HfOx. However, in sputtered SiOx, Pd cation transport was revealed, accompanied by the formation of nano-crystalline Pd filament(s) in the junctions. Based on these observations, memristors with reversible and repeatable switching were obtained by using Pd doped SiOx as the switching material.In a normal electrochemical metallization (ECM) switch, electrochemically active metals, such as Ag and Cu are used to provide mobile ions for the conducting filament. In both ECM and valence change memory (VCM) devices, platinum group metals, such as Pt and Pd, are typically used as the counter electrode and assumed to be chemically and physically inert. In this study, we explore whether the so-called inert metal itself can form a conducting filament and result in repeatable resistance switching. Pd and different oxide host matrices are used for this purpose. We have observed that the transport of oxygen anions dominates over Pd metal cations in ALD deposited AlOx and HfOx. However, in sputtered SiOx, Pd cation transport was revealed, accompanied by the formation of nano-crystalline Pd filament(s) in the junctions. Based on these observations, memristors with reversible and repeatable switching were obtained by using Pd doped SiOx as the switching material. Electronic supplementary information (ESI) available

  4. Highly active oxygen reduction non-platinum group metal electrocatalyst without direct metal-nitrogen coordination

    NASA Astrophysics Data System (ADS)

    Strickland, Kara; Miner, Elise; Jia, Qingying; Tylus, Urszula; Ramaswamy, Nagappan; Liang, Wentao; Sougrati, Moulay-Tahar; Jaouen, Frédéric; Mukerjee, Sanjeev

    2015-06-01

    Replacement of noble metals in catalysts for cathodic oxygen reduction reaction with transition metals mostly create active sites based on a composite of nitrogen-coordinated transition metal in close concert with non-nitrogen-coordinated carbon-embedded metal atom clusters. Here we report a non-platinum group metal electrocatalyst with an active site devoid of any direct nitrogen coordination to iron that outperforms the benchmark platinum-based catalyst in alkaline media and is comparable to its best contemporaries in acidic media. In situ X-ray absorption spectroscopy in conjunction with ex situ microscopy clearly shows nitrided carbon fibres with embedded iron particles that are not directly involved in the oxygen reduction pathway. Instead, the reaction occurs primarily on the carbon-nitrogen structure in the outer skin of the nitrided carbon fibres. Implications include the potential of creating greater active site density and the potential elimination of any Fenton-type process involving exposed iron ions culminating in peroxide initiated free-radical formation.

  5. A Capped Octahedral MHC6 Compound of a Platinum Group Metal.

    PubMed

    Eguillor, Beatriz; Esteruelas, Miguel A; Lezáun, Virginia; Oliván, Montserrat; Oñate, Enrique; Tsai, Jui-Yi; Xia, Chuanjun

    2016-06-27

    A MHC6 complex of a platinum group metal with a capped octahedral arrangement of donor atoms around the metal center has been characterized. This osmium compound OsH{κ(2) -C,C-(PhBIm-C6 H4 )}3 , which reacts with HBF4 to afford the 14 e(-) species [Os{κ(2) -C,C-(PhBIm-C6 H4 )}(Ph2 BIm)2 ]BF4 stabilized by two agostic interactions, has been obtained by reaction of OsH6 (PiPr3 )2 with N,N'-diphenylbenzimidazolium chloride ([Ph2 BImH]Cl) in the presence of NEt3 . Its formation takes place through the C,C,C-pincer compound OsH2 {κ(3) -C,C,C-(C6 H4 -BIm-C6 H4 )}(PiPr3 )2 , the dihydrogen derivative OsCl{κ(2) -C,C-(PhBIm-C6 H4 )}(η(2) -H2 )(PiPr3 )2 , and the five-coordinate osmium(II) species OsCl{κ(2) -C,C-(PhBIm-C6 H4 )}(PiPr3 )2 . PMID:27123555

  6. Highly active oxygen reduction non-platinum group metal electrocatalyst without direct metal–nitrogen coordination

    PubMed Central

    Strickland, Kara; Miner, Elise; Jia, Qingying; Tylus, Urszula; Ramaswamy, Nagappan; Liang, Wentao; Sougrati, Moulay-Tahar; Jaouen, Frédéric; Mukerjee, Sanjeev

    2015-01-01

    Replacement of noble metals in catalysts for cathodic oxygen reduction reaction with transition metals mostly create active sites based on a composite of nitrogen-coordinated transition metal in close concert with non-nitrogen-coordinated carbon-embedded metal atom clusters. Here we report a non-platinum group metal electrocatalyst with an active site devoid of any direct nitrogen coordination to iron that outperforms the benchmark platinum-based catalyst in alkaline media and is comparable to its best contemporaries in acidic media. In situ X-ray absorption spectroscopy in conjunction with ex situ microscopy clearly shows nitrided carbon fibres with embedded iron particles that are not directly involved in the oxygen reduction pathway. Instead, the reaction occurs primarily on the carbon–nitrogen structure in the outer skin of the nitrided carbon fibres. Implications include the potential of creating greater active site density and the potential elimination of any Fenton-type process involving exposed iron ions culminating in peroxide initiated free-radical formation. PMID:26059552

  7. Electrochemical metallization switching with a platinum group metal in different oxides.

    PubMed

    Wang, Zhongrui; Jiang, Hao; Hyung Jang, Moon; Lin, Peng; Ribbe, Alexander; Xia, Qiangfei; Yang, J Joshua

    2016-08-01

    In a normal electrochemical metallization (ECM) switch, electrochemically active metals, such as Ag and Cu are used to provide mobile ions for the conducting filament. In both ECM and valence change memory (VCM) devices, platinum group metals, such as Pt and Pd, are typically used as the counter electrode and assumed to be chemically and physically inert. In this study, we explore whether the so-called inert metal itself can form a conducting filament and result in repeatable resistance switching. Pd and different oxide host matrices are used for this purpose. We have observed that the transport of oxygen anions dominates over Pd metal cations in ALD deposited AlOx and HfOx. However, in sputtered SiOx, Pd cation transport was revealed, accompanied by the formation of nano-crystalline Pd filament(s) in the junctions. Based on these observations, memristors with reversible and repeatable switching were obtained by using Pd doped SiOx as the switching material. PMID:27166623

  8. Leaching platinum-group metals in a sulfuric acid/chloride solution

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. H. H.

    2003-04-01

    A leaching process was established based on the ability of platinum-group metals to form stable chloro-complexes in acidic chloride solutions. Industrial catalyst losses were examined for the recovery of platinum, palladium, and rhodium by leaching with a mixture of sulfuric acid and sodium chloride to avoid using aqua regia or autoclave conditions. Extraction of platinum and rhodium in 60% H2SO4 at 135°C steadily increased with increasing NaCl concentrations reaching 95% and 85%, respectively, at 0.1 M NaCl after two hours. By comparison, palladium was dissolved more quickly but also reached 85% under the same conditions. Extraction of each metal increased with temperatures up to 125°C but plateaued at higher temperatures. Similar behavior was observed with increasing H2SO4 concentrations up to 60%. More than 99% extraction of each metal was obtained after ten hours using 0.1 M NaCl and 60% H2SO4 at 125°C.

  9. Fractionation of the platinum-group elments and Re during crystallization of basalt in Kilauea Iki Lava Lake, Hawaii

    USGS Publications Warehouse

    Pitcher, L.; Helz, R.T.; Walker, R.J.; Piccoli, P.

    2009-01-01

    Kilauea Iki lava lake formed during the 1959 summit eruption of Kilauea Volcano, then crystallized and differentiated over a period of 35??years. It offers an opportunity to evaluate the fractionation behavior of trace elements in a uniquely well-documented basaltic system. A suite of 14 core samples recovered from 1967 to 1981 has been analyzed for 5 platinum-group elements (PGE: Ir, Os, Ru, Pt, Pd), plus Re. These samples have MgO ranging from 2.4 to 26.9??wt.%, with temperatures prior to quench ranging from 1140????C to ambient (110????C). Five eruption samples were also analyzed. Osmium and Ru concentrations vary by nearly four orders of magnitude (0.0006-1.40??ppb for Os and 0.0006-2.01??ppb for Ru) and are positively correlated with MgO content. These elements behaved compatibly during crystallization, mostly likely being concentrated in trace phases (alloy or sulfide) present in olivine phenocrysts or included chromite. Iridium also correlates positively with MgO, although less strongly than Os and Ru. The somewhat poorer correlation for Ir, compared with Os and Ru, may reflect variable loss of Ir as volatile IrF6 in some of the most magnesian samples. Rhenium is negatively correlated with MgO, behaving as an incompatible trace element. Its behavior in the lava lake is complicated by apparent volatile loss of Re, as suggested by a decrease in Re concentration with time of quenching for lake samples vs. eruption samples. Platinum and Pd concentrations are negatively, albeit weakly, correlated with MgO, so these elements were modestly incompatible during crystallization of the major silicate phases. Palladium contents peaked before precipitation of immiscible sulfide liquid, however, and decline sharply in the most differentiated samples. In contrast, Pt appears to have been unaffected by sulfide precipitation. Microprobe data confirm that Pd entered the sulfide liquid before Re, and that Pt is not strongly chalcophile in this system. Occasional high Pt values

  10. Accumulation and oxidation of elemental mercury in tropical soils.

    PubMed

    Soares, Liliane Catone; Egreja Filho, Fernando Barboza; Linhares, Lucília Alves; Windmoller, Cláudia Carvalhinho; Yoshida, Maria Irene

    2015-09-01

    The role of chemical and mineralogical soil properties in the retention and oxidation of atmospheric mercury in tropical soils is discussed based on thermal desorption analysis. The retention of gaseous mercury by tropical soils varied greatly both quantitatively and qualitatively with soil type. The average natural mercury content of soils was 0.08 ± 0.06 μg g(-1) with a maximum of 0.215 ± 0.009 μg g(-1). After gaseous Hg(0) incubation experiments, mercury content of investigated soils ranged from 0.6 ± 0.2 to 735 ± 23 μg g(-1), with a mean value of 44 ± 146 μg g(-1). Comparatively, A horizon of almost all soil types adsorbed more mercury than B horizon from the same soil, which demonstrates the key role of organic matter in mercury adsorption. In addition to organic matter, pH and CEC also appear to be important soil characteristics for the adsorption of mercury. All thermograms showed Hg(2+) peaks, which were predominant in most of them, indicating that elemental mercury oxidized in tropical soils. After four months of incubation, the thermograms showed oxidation levels from 70% to 100%. As none of the samples presented only the Hg(0) peak, and the soils retained varying amounts of mercury despite exposure under the same incubation conditions, it became clear that oxidation occurred on soil surface. Organic matter seemed to play a key role in mercury oxidation through complexation/stabilization of the oxidized forms. The lower percentages of available mercury (extracted with KNO3) in A horizons when compared to B horizons support this idea. PMID:25950134

  11. A histopathological study of Hudson River crayfish, Orconectes virilis, exposed to platinum group metals.

    PubMed

    Wren, Melody; Gagnon, Zofia E

    2014-01-01

    Platinum group metals (PGMs), such as platinum (Pt), palladium (Pd), and rhodium (Rh), are of increasing concern due to rising anthropogenic input to aquatic systems. In this study, PGMs' effects on bioaccumulation and histopathological changes were investigated using Orconectes virilis, a native Hudson River crayfish, as a model. Organisms were exposed to varying concentrations of water-soluble PGM salts for 10 days. The following experimental treatments were established: 0.0, 1.0, 5.0, 10.0 ppm Pt(IV), 1.0 ppm Rh(III), 1.0 ppm Pd(II), and a PGM mix (1.0 ppm Pt(IV), Rh(III), Pd(II) each) dissolved in raw Hudson River water. Metal content in the tissue samples were analyzed by a Spectro Genesis ICP-OES. The relationship between Pt, Pd, and Rh concentrations in different treatments and observed behavioral changes during the experiment was analyzed through One-Way ANOVA Student-Newman-Keuls multiple comparison test (P ≤ 0.05). Paraffin sections, 6-μm-thick, were prepared in standard eosin-Y and hematoxylin-2 stain and examined for histological abnormalities within hepatopancreas, exoskeleton, brain, and ganglia tissue. Statistically significant differences in PGM bioaccumulation were observed in all organs, with highest concentrations found in the hepatopancreas, 81.68 mg g(-1) dw in 1.0 ppm Pd treatment, 20.03 mg g(-1) dw Rh in 1.0 ppm Rh treatment, and 81.58 mg g(-1) dw Pt in the 5.0 ppm Pt treatment. Pt bioaccumulation in the hepatopancreas and exoskeleton decreased at the highest Pt exposure treatment, suggesting severe structural damage to tissue. Hyper-segmentation of vacuoles and swelling of the vascular channels were observed in the hepatocyte structure of the hepatopancreas. Exoskeleton exhibited visible bands in the exocuticle indicating demineralization. Brain and ganglia demonstrated extensive vacuolization. Behavioral analysis showed an increase of maximum response intensity over the experimental period within each treatment

  12. Root anatomy and element distribution vary between two Salix caprea isolates with different Cd accumulation capacities

    PubMed Central

    Vaculík, Marek; Konlechner, Cornelia; Langer, Ingrid; Adlassnig, Wolfram; Puschenreiter, Markus; Lux, Alexander; Hauser, Marie-Theres

    2012-01-01

    The understanding of the influence of toxic elements on root anatomy and element distribution is still limited. This study describes anatomical responses, metal accumulation and element distribution of rooted cuttings of Salix caprea after exposure to Cd and/or Zn. Differences in the development of apoplastic barriers and tissue organization in roots between two distinct S. caprea isolates with divergent Cd uptake and accumulation capacities in leaves might reflect an adaptive predisposition based on different natural origins. Energy-dispersive X-ray spectroscopy (EDX) revealed that Cd and Zn interfered with the distribution of elements in a tissue- and isolate-specific manner. Zinc, Ca, Mg, Na and Si were enriched in the peripheral bark, K and S in the phloem and Cd in both vascular tissues. Si levels were lower in the superior Cd translocator. Since the cuttings originated from stocks isolated from polluted and unpolluted sites we probably uncovered different strategies against toxic elements. PMID:22325439

  13. Uptake and bioaccumulation of platinum group metals (Pd, Pt, Rh) from automobile catalytic converter materials by the zebra mussel (Dreissena polymorpha).

    PubMed

    Zimmermann, Sonja; Messerschmidt, Jürgen; von Bohlen, Alex; Sures, Bernd

    2005-06-01

    The uptake and bioaccumulation of the platinum group metals (PGM) platinum (Pt), palladium (Pd), and rhodium (Rh) by the zebra mussel (Dreissena polymorpha) were investigated in exposure studies using ground material from unused automobile catalytic converters as metal source. The mussels were exposed to the metals in tap water or humic water. In the soft tissue samples of exposed mussels mean Pt levels ranged in dependence on the type of tank water and the exposure period (6, 9, or 18 weeks) between 780 and 4300 ng/g, the Pd levels ranged between 720 and 6300 ng/g, and the Rh levels ranged between 270 and 1900 ng/g. In contrast, the control mussels had metal concentrations of <20 ng/g (Pt), <50 ng/g (Pd), and <40 ng/g (Rh). Considerably higher PGM levels were found in the exposed mussels of the humic water group than in those of the tap water group. Although there is a cumulative increase of the PGM concentrations in the environment since the introduction of the automobile catalyst more than 20 years ago, only little information about the PGM contamination in the biosphere, especially the fauna, is available. Due to the high capacity of D. polymorpha to accumulate PGM, this bivalve could be used as a potential sentinel for monitoring the noble metals in aquatic ecosystems. PMID:15820726

  14. The investigation of heavy element accumulation in some Hydrophilidae (Coleoptera) species.

    PubMed

    Aydoğan, Zeynep; Gürol, Ali; İncekara, Ümit

    2016-04-01

    First of all, this study aimed to find out the measures of some heavy elements (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Sr, Pb) as heavy element pollution in Erzurum Province, and secondly to observe whether some hydrophilidae (Coleoptera) species can be used as a biomonitor. Insect samples were collected from five different localities of Erzurum in June, July, and August 2014. Heavy element levels in sediment, water, and insect samples were analyzed by energy-dispersive X-ray fluorescence (EDXRF) spectrometer device. According to the results of analysis derived through EDXRF spectrometry, heavy element concentrations display differences between stations and also species. The results pointed out that the insects were contaminated by the sediment and water; therefore, some hydrophilidae species accumulate higher concentration of elements than their environment. Results for levels in water were compared to national water quality guidelines. The values of some heavy elements found at higher concentration than acceptable limits. PMID:26935735

  15. Peatlands as Dynamic Biogeochemical Ecotones: Elemental Concentrations, Stoichiometries and Accumulation in Peatland Soils of Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Moore, T. R.; Wang, M.; Talbot, J.; Riley, J. L.

    2015-12-01

    Peatlands act as biogeochemical interfaces between terrestrial and aquatic systems and are 'hotspots', particularly for carbon cycling and the accumulation of nutrients and other elements within the peat profile. This results in storage of substantial amounts of carbon, nutrients and metals, particularly in northern peatlands. Using a data base of over 400 peat profiles and 1700 individual peat samples from bog, fen and swamp sites in Ontario, Canada, we examine the profile concentrations of C, N, P, Ca, Mg, K, Hg, Pb, As, Cu, Mn, Zn, Fe and Al, and estimate the storage and accumulation of these elements. We show how these profiles, spatial patterns, stoichiometries and accumulation rates are controlled by biogeochemical processes and influenced by geochemical setting, hydrology, atmospheric input and pollution, and ecological and microbial transformations.

  16. Micro-PIXE studies of elemental distribution in Cd-accumulating Brassica juncea L.

    NASA Astrophysics Data System (ADS)

    Schneider, Thorsten; Haag-Kerwer, Angela; Maetz, Mischa; Niecke, Manfred; Povh, Bogdan; Rausch, Thomas; Schüßler, Arthur

    1999-10-01

    Brassica juncea L. is a high biomass producing crop plant, being able to accumulate Cd and other heavy metals in their roots and shoots. It is a good candidate for efficient phytoextraction of heavy metals - such as Cd - from polluted soils. PIXE and STIM analyses were applied to investigate Cd-uptake in roots and the resulting effects on the elemental distribution of Cd stressed plants. The axial distribution of trace elements as a function of distance from the root tip as well as the radial distribution within cross-sections were analysed. The results are compared with the elemental distribution in control plants.

  17. Global exploration and production capacity for platinum-group metals from 1995 through 2015

    USGS Publications Warehouse

    Wilburn, David R.

    2012-01-01

    Platinum-group metals (PGMs) are required in a variety of commercial, industrial, and military applications for many existing and emerging technologies, yet the United States is highly dependent on foreign sources of PGMs. Information on global exploration for PGMs since 1995 has been used in this study as a basis for identifying locations where the industry has determined that exploration has provided data sufficient to warrant development of a new mine or expansion of an existing operation or where a significant increase in capacity for PGMs is anticipated by 2015. Discussions include an overview of the industry and the selected sites, factors affecting mineral supply, and circumstances leading to the development of mineral properties with the potential to affect mineral supply. Of the 52 sites or regional operations that were considered in this analysis, 16 sites were producing before 1995, 28 sites commenced production from 1995 through 2010, and 8 sites were expected to begin production from 2011 through 2015 if development plans came to fruition. The United States imports PGMs primarily from Canada, Russia, South Africa, and Zimbabwe to meet increasing demand for these materials in a variety of specialized and high-tech applications. Feed sources of PGMs are changing in South Africa and Russia, which together accounted for about 89 percent of platinum production and 82 percent of palladium production in 2009. A greater amount of South African PGM capacity is likely to come from deeper, higher cost Upper Group Reef seam 2 deposits and deposits in the Eastern Bushveld area. Future Russian PGM capacity is likely to come from ore zones with generally lower PGM content and different platinum-to-palladium ratios than the nickel-rich ore that dominated PGM supply in the 1990s. Because PGM supply from Canada and Russia is derived as a byproduct of copper and nickel mining, the PGM supply from these countries is influenced by economic, environmental, political, and

  18. Accumulation of trace elements in harp seals (Phoca groenlandica) from Pangnirtung in the Baffin Island, Canada.

    PubMed

    Agusa, Tetsuro; Nomura, Kumiko; Kunito, Takashi; Anan, Yasumi; Iwata, Hisato; Tanabe, Shinsuke

    2011-01-01

    Nineteen trace elements were determined in liver, muscle, kidney, gonads, and hair of 18 harp seals (Phoca groenlandica) from Pangnirtung in the Baffin Island, Canada. Concentrations of V, Mn, Fe, Cu, Mo, Ag, and Hg in the liver, Co, Cd, and Tl in the kidney, and Ba and Pb in the hair were significantly higher than those in other tissues. Significant positive correlations between Hg concentrations in the hair, and liver, kidney and testis imply usefulness of the hair sample for non-destructive monitoring of Hg in the harp seals. It is suggested that whereas Hg preferentially accumulates in the liver, the accumulation in other tissues is induced at higher hepatic Hg levels. In contrast, Se may not be accumulated in other tissues compared with the liver even at higher hepatic Hg levels because of the presence of excess Se for Hg detoxification in other tissues. PMID:21411109

  19. Elemental accumulation in lichen transplants in the neighborhood of thermal power stations

    SciTech Connect

    Freitas, M.C.; Reis, M.A.; Alves, L.C.

    1996-12-31

    Lichens are known to be good monitors of air pollution because they easily absorb the chemical elements from air particles. Therefore, the exposure of clean lichens to a polluted region will result in an accumulation of elements emitted by the pollution sources in the lichens. In this work, samples of the lichen Parmelia sulcata were collected from olive tree stems and in a very clean area to gauge pollution. The goal is to obtain a quantitative relation between results obtained via lichens and via airborne particles.

  20. Seedling emergence, growth and trace elements tolerance and accumulation by Lamiaceae species in a mine soil.

    PubMed

    Parra, A; Zornoza, R; Conesa, E; Gómez-López, M D; Faz, A

    2014-10-01

    The potential use of three Laminaceae species (Lavandula dentata, Rosmarinus officinalis and Thymus vulgaris) for the phytostabilisation of a trace elements contaminated (acid) soil has been evaluated. These species were grown in mine tailing soil unamended (TS) and amended with calcium carbonate and pig manure (ATS), and unpolluted substrate for control (CT); plant growth, root characterisation, soil trace elements contents and their accumulation in plants were measured. Results indicated that seed emergence was independent from substrate characteristics, but seedlings died in TS with 40% survival in ATS. The biomass of L. dentata and T. vulgaris and root development in R. officinalis were negatively affected when grown in TS but without differences between ATS and CT. Applicating amendments reduced soil exchangeable and extractable fractions concentrations of trace elements in ATS compared with TS. The establishment of L. dentata and R. officinalis were related to trace elements immobilisation. Trace element concentrations in plants grown in tailing soils were similar to those reported for control, although applicating amendments reduced Zn accumulation in all species, and favoured increased absorption and aerial translocation of As and Pb by L. dentata and T. vulgaris; nonetheless, levels were below toxicity thresholds. Thus, these species fulfill the criteria for phytostabilisation purposes, aided by employing amendments. PMID:25065800

  1. Accumulation of airborne elements from vehicles in transplanted lichens in urban sites

    SciTech Connect

    Garty, J.; Kauppi, M.; Kauppi, A.

    1996-03-01

    The objective of the current study is to compare the short-term accumulation capacity of two epiphytic lichens characterized by a different type of thallus. The lichens Hypogynmia physodes (L.) Nyl. and Usnea hirta (L.) Weber em. Mot. were transplanted either to the vicinity of streets of low volume and slow traffic or to the vicinity of a highway in the city of Oulu, N. Finland, for a period of 45 d. Eleven elements were analyzed before and after transplantation. The two lichen species were found to possess a similar accumulating capacity for K and Mn. Hypogynmia physodes manifests a higher accumulating capacity than U. hirta for Na, Fe, and Cu. whereas the more sensitive lichen U. hirta exhibits a higher accumulating capacity for Mg, despite a higher primary concentration of these elements in the thallus of H. physodes. Our findings show a relative high concentration of K, Fe, Mg, Zn, Mn, Pb, and Cu in thalli of H. physodes and Mg, Zn, Pb, Cu, and Cd in U. hirta in material transplanted to streets of low volume and slow traffic, over and above the concentration found in thalli retrieved form the vicinity of the highway. This may be explained by the higher rate of abrasion of car engines running idle near traffic lights and by the lesser ventilation near the close-clustered streets of the inner city. 65 refs., 8 tabs.

  2. The feasibility of RIMS for the analysis of potentially toxic element accumulation in neural tissue

    SciTech Connect

    Jones, O. Rhodri; Abraham, Christopher J.; Telle, Helmut H.; Oakley, Arthur E.

    1997-01-15

    A feasibility study was conducted into the possibility of using resonance ionisation mass spectrometry for the detection of focal accumulation of neuro-toxic elements in neural tissue. Experiments were performed using a ToFMS system in conjunction with an Ar{sup +} source for target sputtering and a pulsed tuneable dye laser system for resonance ionisation. Detection limits of {approx}3 ppm for Al in brain tissue homogenates were achieved, with a spatial resolution of less than 100 {mu}m.

  3. The Comparative Study of Element Accumulation in Wood Fen Peat (Latvia)

    NASA Astrophysics Data System (ADS)

    Krumins, Janis; Klavins, Maris; Kuske, Eliza; Seglins, Valdis; Kaup, Enn

    2013-04-01

    Mires belong to the most representative archives of past environmental conditions in large areas of temperate and subarctic zone. Moreover, mires keep evidence of ancient cultures and modern human activity. Consequently the research of mires is an integral part of global change studies. Fens are less studied than bogs; one of the reasons is the complexity of factors that impact peat formation. Bogs, due to dome-shaped structure, are affected by precipitation, while other external influences are negligible and simply separable. The aim of this research was the characterization of accumulation patterns of metallic elements in wood fen peat profiles and to assess their accumulation regularities in relation with peat properties. The general idea was to find out how admixtures of plant remains in different stages of decomposition change properties and the element accumulation character in a wood peat. In obtained profiles were separated five types of wood peat: wood, wood-sedge, wood-reed, wood-grass and wood- sphagnum peat. Peat was sampled in four Latvian fens: Elki, Viki, Svetupe and Sala. Similar environment, origin and development of sites suggest similar development of peat properties thus there is no reason to assume different impact on peat development among mires. Despite a slow decomposition rate, results point to a higher decomposition degree of wood peat, in comparison with other types of fen peat. In average, wood peat forms the thickest layers, but it must be taken into account that thickness depends on coating layers, presence of decomposed plant remains etc. The accumulation pattern of metallic elements in a wood fen peat slightly differs among sites, but the difference among wood peat types is clearly evident. For instance, the highest amount of iron is characteristic to wood-reed peat, while, the lowest, is in wood-sphagnum peat. At the same time, in wood-reed peat the lowest amounts of magnesium were found while the highest amount of Mg was in wood

  4. Phytoaccumulation of trace elements by wetland plants: 3. Uptake and accumulation of ten trace elements by twelve plant species

    SciTech Connect

    Qian, J.H.; Zayed, A.; Zhu, Y.L.; Yu, M.; Terry, N.

    1999-10-01

    Interest is increasing in using wetland plants in constructed wetlands to remove toxic elements from polluted wastewater. To identify those wetland plants that hyperaccumulate trace elements, 12 plant species were tested for their efficiency to bioconcentrate 10 potentially toxic trace elements including As, b, Cd, Cr, Cu, Pb, Mn, Hg, Ni, and Se. Individual plants were grown under carefully controlled conditions and supplied with 1 mg L{sup {minus}1} of each trace element individually for 10 d. Except B, all elements accumulated to much higher concentrations in roots than in shoots. Highest shoot tissue concentrations (mg kg{sup {minus}1} DW) of the various trace elements were attained by the following species: umbrella plant (Cyperus alternifolius L.) for Mn (198) and Cr (44); water zinnia (Wedelia trilobata Hitchc.) for Cd (148) and Ni (80); smartweed (Polygonum hydropiperoides Michx.) for Cu (95) and Pb (64); water lettuce (Pistia stratiotes L.) for Hg (92), As (34), and Se (39); and mare's tail (hippuris vulgaris L.) for B (1132). Whereas, the following species attained the highest root tissue concentrations (mg kg{sup {minus}1} DW); stripped rush (Baumia rubiginosa) for Mn (1683); parrot's feather (Myriophyllum brasiliense Camb.) for Cd (1426) and Ni (1077); water lettuce for Cu (1038), Hg (1217), and As (177); smartweed for Cr (2980) and Pb (1882); mare's tail for B (1277); and monkey flower (Mimulus guttatus Fisch.) for Se (384). From a phytoremediation perspective, smartweed was probably the best plant species for trace element removal from wastewater due to its faster growth and higher plant density.

  5. Early Diagenesis and Trace Element Accumulation in North American Arctic Margin Sediments

    NASA Astrophysics Data System (ADS)

    Kuzyk, Z. Z. A.; Gobeil, C.; Goni, M. A.; Macdonald, R. W.

    2014-12-01

    Concentrations of redox-sensitive elements (S, Mn, Mo, U, Cd, Re) were analyzed in a set of 27 sediment cores collected along a section extending from the North Bering Sea to Davis Strait via the Canadian Archipelago. Sedimentary distributions and accumulation rates of the elements were used to document the early diagenetic properties of North American Arctic margin sediments and to estimate the importance of this margin as a sink for key elements in the Arctic and global ocean. Distributions of Mn, total S and reduced inorganic S demonstrated that most sediments had relatively thick (>1 cm) surface oxic layers underlain by weakly reducing conditions, reflecting limited sulphate reduction. Strongly reducing conditions sufficient for significant sulphate reduction and strong sedimentary pyrite burial occurred only in certain subregions, including the Bering-Chukchi Shelves, shallow portions of Barrow Canyon, and, to a lesser extent, Lancaster Sound. Estimated accumulation rates of authigenic S, Mo, Cd and U, and total Re displayed marked spatial variability related to sedimentary redox conditions. Strong relationships between the accumulation rates and vertical carbon flux, estimated from regional primary production values and water depth at the coring sites, indicate that the primary driver in the regional patterns is variation in labile carbon forcing. After accounting for the influence of carbon flux, authigenic Mo accumulation rates show a significant relationship with vascular plant input to the sediments, implying that terrestrial organic matter contributes to supporting metabolism in Arctic margin sediments. In the Chukchi Shelf, where our cores represent a sizeable area (~140,000 km2), and where we encountered the strongest reducing conditions and highest authigenic element accumulation rates in sediments, we estimate that the total authigenic S, Mo, Cd and U accumulation may account for as much as 9% of the pyrite S, 14% of the Mo, 6%-24% of the Cd, and 10

  6. Placer and lode platinum-group minerals in south Kalimantan, Indonesia: evidence for derivation from Alaskan-type ultramafic intrusions

    USGS Publications Warehouse

    Zientek, M.L.

    1992-01-01

    Platinum-group minerals occur in significant proportions in placer deposits in several localities in South Kalimantan. They consist of Pt-Fe alloy that may be intergrown with or contain inclusions of Ir-Os-Ru alloy, laurite and chromite. Alluvial PGM found along Sungai Tambanio are in part derived from chromatite schlieren in dunitic bodies intruded into clinopyroxene cumulates that may be part of an Alaskan-type ultramafic complex. A chromitite schlieren in serpentinite from one of these dunitic bodies is anomalous in PGE. The chondrite-normalized PGE pattern for this rock, pan concentrates from this area, and PGM concentrates from diamond-Au-PGM placer deposits have an "M'-shaped pattern enriched in Ir and Pt that is typical of PGE-mineralization associated with Alaskan-type ultramafic complexes. -Authors

  7. Linking structure to function: The search for active sites in non-platinum group metal oxygen reduction reaction catalysts

    DOE PAGESBeta

    Holby, Edward F.; Zelenay, Piotr

    2016-05-17

    Atomic-scale structures of oxygen reduction reaction (ORR) active sites in non-platinum group metal (non-PGM) catalysts, made from pyrolysis of carbon, nitrogen, and transition-metal (TM) precursors have been the subject of continuing discussion in the fuel cell electrocatalysis research community. We found that quantum chemical modeling is a path forward for understanding of these materials and how they catalyze the ORR. Here, we demonstrate through literature examples of how such modeling can be used to better understand non-PGM ORR active site relative stability and activity and how such efforts can also aid in the interpretation of experimental signatures produced by thesemore » materials.« less

  8. A Generic Wet Impregnation Method for Preparing Substrate-Supported Platinum Group Metal and Alloy Nanoparticles with Controlled Particle Morphology.

    PubMed

    Zhang, Changlin; Oliaee, Shirin Norooz; Hwang, Sang Youp; Kong, Xiangkai; Peng, Zhenmeng

    2016-01-13

    Mass production of shape-controlled platinum group metal (PGM) and alloy nanoparticles is of high importance for their many fascinating properties in catalysis, electronics, and photonics. Despite of successful demonstrations at milligram scale using wet chemistry syntheses in many fundamental studies, there is still a big gap between the current methods and their real applications due to the complex synthetic procedures, scale-up difficulty, and surface contamination problem of the made particles. Here we report a generic wet impregnation method for facile, surfactant-free, and scalable preparation of nanoparticles of PGMs and their alloys on different substrate materials with controlled particle morphology and clean surface, which bridges the outstanding properties of these nanoparticles to practical important applications. The underlying particle growth and shape formation mechanisms were investigated using a combination of ex situ and in situ characterizations and were attributed to their different interactions with the applied gas molecules. PMID:26642094

  9. High temperature rheological study of borosilicate glasses containing platinum group metal particles by means of a mixer-type rheometer

    NASA Astrophysics Data System (ADS)

    Puig, Jean; Hanotin, Caroline; Neyret, Muriel; Marchal, Philippe

    2016-02-01

    In this paper, the rheological behavior of six simulated high level waste nuclear glasses containing 0 to 5.2 wt% platinum group metals (PGM) has been studied at a temperature of 1200 °C. By means of a stress imposed rheometer, the shear stress dependence of the viscosity, which was so far assessed only at high shear rates, has been investigated on a wider range. Experimental data have been well fitted by the Cross model and a critical stress corresponding to the rupture of PGM aggregates has been evidenced. At high shear rates, the dependence with the volume fraction in PGM particles is well accounted for by Quemada's law. At low shear rates, the first Newtonian plateau is shown to be strongly dependent on the PGM content, notably above 3 wt% and to follow an exponential dependence due to the existence of more complex structures at the origin of the critical stress.

  10. Highly efficient platinum group metal free based membrane-electrode assembly for anion exchange membrane water electrolysis.

    PubMed

    Pavel, Claudiu C; Cecconi, Franco; Emiliani, Chiara; Santiccioli, Serena; Scaffidi, Adriana; Catanorchi, Stefano; Comotti, Massimiliano

    2014-01-27

    Low-temperature electricity-driven water splitting is an established technology for hydrogen production. However, the two main types, namely proton exchange membrane (PEM) and liquid alkaline electrolysis, have limitations. For instance, PEM electrolysis requires a high amount of costly platinum-group-metal (PGM) catalysts, and liquid alkaline electrolysis is not well suited for intermittent operation. Herein we report a highly efficient alkaline polymer electrolysis design, which uses a membrane-electrode assembly (MEA) based on low-cost transition-metal catalysts and an anion exchange membrane (AEM). This system exhibited similar performance to the one achievable with PGM catalysts. Moreover, it is very suitable for intermittent power operation, durable, and able to efficiently operate at differential pressure up to 3 MPa. This system combines the benefits of PEM and liquid alkaline technologies allowing the scalable production of low-cost hydrogen from renewable sources. PMID:24339230

  11. Element accumulation, distribution, and phytoremediation potential in selected metallophytes growing in a contaminated area.

    PubMed

    Nadgórska-Socha, Aleksandra; Kandziora-Ciupa, Marta; Ciepał, Ryszard

    2015-07-01

    The distribution of elements in three pseudometallophytes species Cardaminopsis arenosa, Plantago lanceolata, and Plantago major, naturally occurring at metalliferous and non-metalliferous sites in southern Poland, was investigated. The accumulation of Al, Cd, Cu, Fe, Mn, Pb, Zn, as well as Ca, P, Na, and K in shoots and roots was measured. The level of the accumulated trace elements (ATE) was visibly higher in C. arenosa and P. lanceolata from metalliferous sites than non-contaminated ones. However, the level of the accumulated nutrient elements (ANE) was visibly higher only in C. arenosa plants. Also, higher potassium share in ANE was found in the shoots of C. arenosa and Plantago species from metalliferous sites than non-contaminated ones. The highest content of Cd, Zn, Pb, Al, Fe, and Mn was found in C. arenosa, which better reflected metal concentrations in the metalliferous and non-metalliferous soil than other plants. In the studied Plantago species, in almost all cases in all sites TF (translocation coefficient) and MR (mobility ratio) were below 1, which indicates they use the excluder strategy. The best accumulation ability was found for C. arenosa. The higher translocation coefficients (TF > 1) for Zn and Cd in C. arenosa shoots make it suitable for phytoextraction from soil, while the lower translocation ratios (TF < 1) for Zn and Cd in Plantago species and also for Pb in C. arenosa make them suitable for phytostabilization. Almost in all cases the plants had enrichment coefficient >2, which suggested that they may act as indicators of the soil metal contamination. PMID:26088758

  12. Trace element accumulation in Cassiopea sp. (Scyphozoa) from urban marine environments in Australia.

    PubMed

    Templeman, Michelle A; Kingsford, Michael J

    2010-03-01

    Jellyfishes are robust, short-lived animals, tolerant to a wide range of environmental conditions and pollutants. The benthic jellyfish, Cassiopea sp. was collected from five locations along the north and eastern coast of Australia and analysed for trace elements to determine if this species has potential as a marine biomonitor. Both the oral arm and bell tissues readily accumulated aluminium, arsenic, barium, cadmium, chromium, copper, iron, manganese and zinc above ambient seawater levels. In contrast, lithium appeared to be actively regulated within the tissues while calcium, magnesium and strontium reflected the ambient environment. The multi-element signatures showed spatial variation, reflecting the geographical separations between locations, with locations closer together showing more similar elemental patterns. The combination of bioaccumulative capacity, life history traits and biophysical aspects indicate that this species has high potential as a biomonitor in coastal marine systems. PMID:19747724

  13. Trace element accumulations in 13 avian species collected from the Kanto area, Japan.

    PubMed

    Horai, Sawako; Watanabe, Izumi; Takada, Hideshige; Iwamizu, Yoshikazu; Hayashi, Terutake; Tanabe, Shinsuke; Kuno, Katsuji

    2007-02-15

    In the present study, concentrations of 13 elements (Li, Cr, Mn, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Hg) were measured in the tissues of the livers, the kidneys, pectoral muscles, lungs and brains of 13 avian species collected from the Kanto area of Japan. The difference in hepatic heavy metal levels of the grey herons from the two sites was compared. Metal levels in the sediment of the Tama River estuary, situated in the Haneda area, were also measured. These results revealed that heavy metal pollution is present in an aquatic area of Haneda. The accumulation patterns of Cu and Zn in the livers of grey herons appeared to be separated into two groups. Additionally, the present study includes the properties of other metal accumulations and their relationships in avian species. PMID:17229456

  14. Ni-rich spinels and platinum group element nuggets condensed from a Late Archaean impact vapour cloud

    NASA Astrophysics Data System (ADS)

    Goderis, Steven; Simonson, Bruce M.; McDonald, Iain; Hassler, Scott W.; Izmer, Andrei; Belza, Joke; Terryn, Herman; Vanhaecke, Frank; Claeys, Philippe

    2013-08-01

    Deciphering Earth's impact history before ∼2 Ga relies heavily on the lunar record and terrestrial spherule layers, which are distal ejecta from large impacts. This study focuses on the Paraburdoo and Reivilo spherule layers in Western Australia and South Africa respectively, that were probably formed by one impact around 2.57 Ga. Both layers contain an aggregate thickness of ∼2 cm of spherules, known as microkrystites. These spherules are up to ∼0.6 mm in diameter and crystallized during flight, but were diagenetically replaced by K-feldspar and phlogopite with remarkable textural retention. Unlike any other Archaean layer, except for the 3.2 Ga S3 layer in the Barberton greenstone belt, the Paraburdoo and Reivilo spherules contain Ni-rich spinel crystals and high concentrations of meteoritic material (up to 357 ng g-1 Ir for bulk samples of several gram). These exceptional characteristics shed new light on the distribution of the meteoritic component carrier phases (metallic alloys dispersed in the pristine glass) and the processes involved in impact spherule formation and secondary alteration.

  15. Photochemistry and charge transfer chemistry of the platinum group elements. Summary progress report, May 1, 1990--April 30, 1993

    SciTech Connect

    Eisenberg, R.

    1992-12-01

    During the past 3 years, progress was made in elucidating the excited state structures of Pt(diimine)(dithiolate) complexes, while more recent efforts focused on the photochemistry of these complexes and electronic structure of other dithiolate systems. A carbonyl-Ir-maleonitrile dithiolate complex is also studied.

  16. Accumulation and partitioning of biomass, nutrients, and trace elements in switchgrass for phytoremediation of municipal biosolids.

    PubMed

    Jeke, Nicholson N; Zvomuya, Francis; Ross, Lisette

    2016-09-01

    In situ phytoremediation of municipal biosolids is a promising alternative to the land spreading and landfilling of biosolids from end-of-life municipal lagoons. Accumulation and partitioning of dry matter, nitrogen (N), phosphorus (P), and trace elements were determined in aboveground biomass (AGB) and belowground biomass (BGB) of switchgrass (Panicum virgatum L.) to determine the harvest stage that maximizes phytoextraction of contaminants from municipal biosolids. Seedlings were transplanted into 15-L plastic pails containing 3.9 kg (dry wt.) biosolids. Biomass yield components and contaminant concentrations were assessed every 14 days for up to 161 days. Logistic model fits to biomass yield data indicated no significant differences in asymptotic yield between AGB and BGB. Switchgrass partitioned significantly more N and P to AGB than to BGB. Maximum uptake occurred 86 days after transplanting (DAT) for N and 102 DAT for P. Harvesting at peak aboveground element accumulation removed 5% of N, 1.6% of P, 0.2% of Zn, 0.05% of Cd, and 0.1% of Cr initially present in the biosolids. These results will contribute toward identification of the harvest stage that will optimize contaminant uptake and enhance in situ phytoremediation of biosolids using switchgrass. PMID:26940512

  17. A New Fungal Isolate, Penidiella sp. Strain T9, Accumulates the Rare Earth Element Dysprosium

    PubMed Central

    Horiike, Takumi

    2015-01-01

    With an aim to develop a highly efficient method for the recovery of rare earth elements (REEs) by using microorganisms, we attempted to isolate dysprosium (Dy)-accumulating microorganisms that grow under acidic conditions from environmental samples containing high concentrations of heavy metals. One acidophilic strain, T9, which was isolated from an abandoned mine, decreased the concentration of Dy in medium that contained 100 mg/liter Dy to 53 mg/liter Dy after 3 days of cultivation at pH 2.5. The Dy content in the cell pellet of the T9 strain was 910 μg/mg of dry cells. The T9 strain also accumulated other REEs. Based on the results of 28S-D1/D2 rRNA gene sequencing and morphological characterization, we designated this fungal strain Penidiella sp. T9. Bioaccumulation of Dy was observed on the cell surface of the T9 strain by elemental mapping using scanning electron microscopy-energy dispersive X-ray spectroscopy. Our results indicate that Penidiella sp. T9 has the potential to recover REEs such as Dy from mine drainage and industrial liquid waste under acidic conditions. PMID:25710372

  18. Growth and elemental accumulation by canola on soil amended with coal fly ash.

    PubMed

    Yunusa, I A M; Manoharan, V; DeSilva, D L; Eamus, D; Murray, B R; Nissanka, S P

    2008-01-01

    To explore the agronomic potential of an Australian coal fly ash, we conducted two glasshouse experiments in which we measured chlorophyll fluorescence, CO2 assimilation (A), transpiration, stomatal conductance, biomass accumulation, seed yield, and elemental uptake for canola (Brassica napus) grown on soil amended with an alkaline fly ash. In Experiment 1, application of up to 25 Mg/ha of fly ash increased A and plant weight early in the season before flowering and seed yield by up to 21%. However, at larger rates of ash application A, plant growth, chlorophyll concentration, and yield were all reduced. Increases in early vigor and seed yield were associated with enhanced uptake of phosphorus (P) by the plants treated with fly ash. Fly ash application did not influence accumulation of B, Cu, Mo, or Zn in the stems at any stage of plant growth or in the seed at harvest, except Mo concentration, which was elevated in the seed. Accumulation of these elements was mostly in the leaves, where concentrations of Cu and Mo increased with any amount of ash applied while that of B occurred only with ash applied at 625 Mg/ha. In Experiment 2, fly ash applied at 500 Mg/ha and mixed into the whole 30 cm soil core was detrimental to growth and yield of canola, compared with restricting mixing to 5 or 15 cm depth. In contrast, application of ash at 250 Mg/ha with increasing depth of mixing increased A and seed yield. We concluded that fly ash applied at not more than 25 Mg/ha and mixed into the top 10 to 15 cm of soil is sufficient to obtain yield benefits. PMID:18453446

  19. Growth and elemental accumulation by canola on soil amended with coal fly ash

    SciTech Connect

    Yunusa, I.A.M.; Manoharan, V.; DeSilva, D.L.; Eamus, D.; Murray, B.R.; Nissanka, S.P.

    2008-05-15

    To explore the agronomic potential of an Australian coal fly ash, we conducted two glasshouse experiments in which we measured chlorophyll fluorescence, CO{sub 2} assimilation (A), transpiration, stomatal conductance, biomass accumulation, seed yield, and elemental uptake for canola (Brassica napus) grown on soil amended with an alkaline fly ash. In Experiment 1, application of up to 25 Mg/ha of fly ash increased A and plant weight early in the season before flowering and seed yield by up to 21%. However, at larger rates of ash application A, plant growth, chlorophyll concentration, and yield were all reduced. Increases in early vigor and seed yield were associated with enhanced uptake of phosphorus (P) by the plants treated with fly ash. Fly ash application did not influence accumulation of B, Cu, Mo, or Zn in the stems at any stage of plant growth or in the seed at harvest, except Mo concentration, which was elevated in the seed. Accumulation of these elements was mostly in the leaves, where concentrations of Cu and Mo increased with any amount of ash applied while that of B occurred only with ash applied at 625 Mg/ha. In Experiment 2, fly ash applied at 500 Mg/ha and mixed into the whole 30 cm soil core was detrimental to growth and yield of canola, compared with restricting mixing to 5 or 15 cm depth. In contrast, application of ash at 250 Mg/ha with increasing depth of mixing increased A and seed yield. We concluded that fly ash applied at not more than 25 Mg/ha and mixed into the top 10 to 15 cm of soil is sufficient to obtain yield benefits.

  20. Determination of platinum group metal catalyst residues in active pharmaceutical ingredients by means of total reflection X-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Marguí, Eva; Queralt, Ignasi; Hidalgo, Manuela

    2013-08-01

    The control of metal catalyst residues (i.e., platinum group metals (PGMs)) in different stages of the manufacturing processes of the active pharmaceutical ingredients (APIs) and, especially, in the final product is crucial. For API specimens, there are strict guidelines to limit the levels of metal residues based on their individual levels of safety concern. For PGMs the concentration limit has been established at 10 mg/kg in the API. Therefore great effort is currently being devoted to the development of new and simple procedures to control metals in pharmaceuticals. In the present work, an analytical methodology based on benchtop total reflection X-ray fluorescence spectrometry (TXRF) has been developed for the rapid and simple determination of some PGM catalyst impurities (Rh, Pd, Ir and Pt) in different types of API samples. An evaluation of different sample treatments (dissolution and digestion of the solid pharmaceutical samples) has been carried out and the developed methodologies have been validated according to the analytical parameters to be considered and acceptance criteria for PGM determination according to the United States Pharmacopeia (USP). Limits of quantification obtained for PGM metals were in the range of 2-4 mg/kg which are satisfactory according to current legislation. From the obtained results it is shown that the developed TXRF method can be implemented in the pharmaceutical industries to increase productivity of the laboratory; offering an interesting and complementary analytical tool to other atomic spectroscopic methods.

  1. Assessing Economic Modulation of Future Critical Materials Use: The Case of Automotive-Related Platinum Group Metals.

    PubMed

    Zhang, Jingshu; Everson, Mark P; Wallington, Timothy J; Field, Frank R; Roth, Richard; Kirchain, Randolph E

    2016-07-19

    Platinum-group metals (PGMs) are technological and economic enablers of many industrial processes. This important role, coupled with their limited geographic availability, has led to PGMs being labeled as "critical materials". Studies of future PGM flows have focused on trends within material flows or macroeconomic indicators. We complement the previous work by introducing a novel technoeconomic model of substitution among PGMs within the automotive sector (the largest user of PGMs) reflecting the rational response of firms to changing prices. The results from the model support previous conclusions that PGM use is likely to grow, in some cases strongly, by 2030 (approximately 45% for Pd and 5% for Pt), driven by the increasing sales of automobiles. The model also indicates that PGM-demand growth will be significantly influenced by the future Pt-to-Pd price ratio, with swings of Pt and Pd demand of as much as 25% if the future price ratio shifts higher or lower even if it stays within the historic range. Fortunately, automotive catalysts are one of the more effectively recycled metals. As such, with proper policy support, recycling can serve to meet some of this growing demand. PMID:27285880

  2. Growth conditions, elemental accumulation and induced physiological changes in Chinese cabbage.

    PubMed

    Moreno, Diego A; Víllora, Gemma; Ruiz, Juan M; Romero, Luis

    2003-08-01

    Soils contaminated with low levels of heavy metals and other trace elements are now frequently used for vegetable growing. In this situation, heavy metals and trace elements from these polluted soils may accumulate in the agricultural plants being grown in them and thereby enter the human food chain. The objectives of this study are to elucidate the effects of growth conditions, manipulated by the crop covers, on the phytoaccumulation of elements, and to investigate the conceivable influences of these conditions on the plant biochemistry. In three consecutive years of field experiments, open air (T(0)), and floating rowcover treatments (T(1): perforated polyethylene 50 micrometers; T(2): polypropylene 17 gm(-2)) were used to produce different environmental conditions for the growth of Chinese cabbage [Brassica rapa L. (Pekinensis group) cv. 'Nagaoka 50']. Five samplings (whole tops) were carried out from transplanting to harvest and measurements of B, Al, Ag, Si and Ca concentration as well as phenolics (orto-diphenols, total phenols and anthocyanins), pectic fractions, amino acids (histidine, phenylalanine and tyrosine) and polyphenol oxidase activity, were carried out in samples. The T(1) (perforated polyethylene sheet) gave greater B, Al, Ag and Si concentration and phytoextraction (in weight units) than the open-air control. These findings can help to develop new cost-effective techniques for phytoremediation as the application of plastic covers in the field. The build-up of heavy metals in those crops would make the product less suitable for human consumption. PMID:12781236

  3. Accumulation of particulate matter and trace elements on vegetation as affected by pollution level, rainfall and the passage of time.

    PubMed

    Przybysz, A; Sæbø, A; Hanslin, H M; Gawroński, S W

    2014-05-15

    Particulate matter is harmful to human health. To reduce its concentration in air, plants could be used as biological filters, accumulating particulate matter on their foliage. In a study carried out at three sites with differing pollution levels and exposure to precipitation, the capacity of evergreen species (Taxus baccata L., Hedera helix L. and Pinus sylvestris L.) to accumulate particulate matter and trace elements from ambient air in urban areas was investigated. The effects of rainfall and the passage of time on particulate matter deposition on foliage were also determined. The results showed that foliage accumulated an increasing quantity of particulate matter in successive months, but the actual amount of particulate matter and trace elements accumulated differed considerably between sites and plant species. The greatest accumulation of air pollutants occurred on the foliage of plants protected from the rain at a site exposed to traffic related pollution and the smallest accumulation at a rural site. Among the species analysed, the deposited mass of particulate matter and trace elements was the greatest on P. sylvestris. In all species, precipitation removed a considerable proportion of particles accumulated on foliage. Most of the removed particulate matter was large size fraction, but little belong to the smallest size fraction. These results showed that both, the dynamics of deposition and leaf washing by rain during the season need to be considered when evaluating the total effect of vegetation in pollutant remediation. PMID:24607629

  4. Elements uptake by metal accumulator species grown on mine tailings amended with three types of biochar.

    PubMed

    Fellet, G; Marmiroli, M; Marchiol, L

    2014-01-15

    Mine tailings are of great concern due to the risk their toxic inorganic elements pose to the environment. The application of biochar as an amendment may be a solution to reduce the risk of pollutant diffusion. The main purpose of the research was to verify the effects of different types of biochar produced from different feedstocks (pruning residues, fir tree pellets and manure pellets) on changing the substrate conditions to promote plant growth for the phytostabilization of mine tailings. The SEM/EDX characterization showed different structures in terms of porosity and granulosity as well as the element composition. The plants used in the pot experiment were Anthyllis vulneraria subsp. polyphylla (Dc.) Nyman, Noccaea rotundifolium (L.) Moench subsp. cepaeifolium and Poa alpina L. subsp. alpina. The biochars were applied at three doses: 0, 1.5 and 3%dw. Although to different extents, the biochars induced significant changes of the substrates in terms of pH, EC, CEC and bioavailability of the metals. The biochar from manure pellets and pruning residues reduced shoot Cd and Pb accumulations. The former also led to a higher biomass production that peaked at the1.5% dose. Biochar has great potential as an amendment for phytoremediation but its effects depend on the type of feedstock it derives from. The characteristics of the substrate to be treated are crucial for the biochar selection. PMID:24056450

  5. Materials discovery by crystal growth: Lanthanide metal containing oxides of the platinum group metals (Ru, Os, Ir, Rh, Pd, Pt) from molten alkali metal hydroxides

    SciTech Connect

    Mugavero, Samuel J.; Gemmill, William R.; Roof, Irina P.; Loye, Hans-Conrad zur

    2009-07-15

    This review addresses the process of materials discovery via crystal growth, specifically of lanthanide metal containing oxides of the platinum group metals (Ru, Os, Ir, Rh, Pd, Pt). It provides a detailed overview of the use of hydroxide fluxes for crystal growth. The melt chemistry of hydroxide fluxes, specifically, the extensive acid base chemistry, the metal cation solubility, and the ability of hydroxide melts to oxidize metals are described. Furthermore, a general methodology for the successful crystal growth of oxides is provided, including a discussion of experimental considerations, suitable reaction vessels, reaction profiles and temperature ranges. Finally, a compilation of complex platinum group metal oxides recently synthesized using hydroxide melts, focusing on their crystal growth and crystal structures, is included. - Graphical abstract: A review that addresses the process of materials discovery via crystal growth using hydroxide fluxes. It provides a detailed overview of the use of hydroxide fluxes for crystal growth and describes the melt chemistry of hydroxide fluxes, specifically, the extensive acid base chemistry, the metal cation solubility, and the ability of hydroxide melts to oxidize metals. In addition, a compilation of complex platinum group metal oxides recently synthesized using hydroxide melts is included.

  6. Accumulation of trace elements and organochlorines by surf scoters wintering in the Pacific northwest

    USGS Publications Warehouse

    Henny, C.J.; Blus, L.J.; Grove, R.A.; Thompson, S.P.

    1991-01-01

    Selenium, cadmium, mercury, copper, manganese, zinc, aluminum, lead, PCBs and DDE were accumulated by segments of the surf scoter (Melanitta perspicillata) population that winters in the Pacific Northwest, but whether the uptake occurred on breeding and/or wintering grounds was uncertain for some contaminants. Surf scoters collected in Puget Sound and San Francisco Bay (in another study) during the same period (January 1985) contained similar concentrations of cadmium, but Alsea Bay scoters contained more. Cadmium was inversely related to both liver and body weights of Northwest scoters in January; similar weight losses were reported in experimental laboratory studies. Northwest and north San Francisco Bay scoters contained similar mercury concentrations, but those in south San Francisco Bay contained higher concentrations. San Francisco Bay scoters contained higher arsenic and selenium concentrations than those in the Northwest; however, the 43.4 ppm (geometric mean, dry wt) selenium in livers at Commencement Bay in January was above levels associated with the reproductive problems in aquatic birds at Kesterson National Wildlife Refuge. Even higher concentrations of some elements may be found in surf scoters in March, because a later collection (March) at San Francisco Bay yielded higher concentrations than found there in January. Trace element concentrations in birds at a given wintering location are variable among species and may be influenced by diet, breeding grounds, and physiology (e.g., at Commencement Bay surf scoters with a sediment-associated diet contained 50X more cadmium in their kidneys than did fish-eating western grebes [Aechmophorus occidentalis]). The numerous wildlife species that live on estuaries require further attention.

  7. Interactions between accumulation of trace elements and major nutrients in Salix caprea after inoculation with rhizosphere microorganisms

    PubMed Central

    De Maria, Susanna; Rivelli, Anna Rita; Kuffner, Melanie; Sessitsch, Angela; Wenzel, Walter W.; Gorfer, Markus; Strauss, Joseph; Puschenreiter, Markus

    2015-01-01

    Although the beneficial effects on growth and trace element accumulation in Salix inoculated with microbes are well known, little information is available on the interactions among trace elements and major nutrients. The main purpose of this study was to assess the effect of inoculation with rhizobacteria Agromyces sp. AR33, Streptomyces sp. AR17, and the combination of each of them with the fungus Cadophora finlandica PRF15 on biomass production and the accumulation of selected trace elements and major nutrients (Cd, Zn, Fe, Ca, K and Mg) in Salix caprea grown on a moderately polluted soil. Dry matter production was significantly enhanced only upon inoculation with Agromyces AR33. Microbial treatments differently affected the accumulation of Zn and Cd in plants. Both the inoculation with Streptomyces AR17 and the co-inoculation of C. finlandica with Agromyces AR33 were most efficient in enhancing the accumulation of Zn and Cd in leaves. These two treatments showed also a higher translocation factor from roots to the leaves for both Cd and Zn. Concentrations of major nutrients in shoots were generally increased in the treatments with the fungus compared to those without, except for K in plants inoculated with bacterial strain Streptomyces AR17. Co-inoculation of C. finlandica plus Agromyces AR33 resulted in a better accumulation of both Zn and Cd and Ca, K and Mg in shoots. This study suggests that the phytoextraction of Zn and Cd can be improved by inoculation with selected microbial strains. PMID:21612812

  8. Interactive effect of ultraviolet-B and mineral nutrients on accumulation and translocation of trace elements in wheat crop.

    PubMed

    Rathore, Dheeraj; Agrawal, S B

    2014-05-01

    Field study was conducted in two wheat cultivars (Triticum aestivum L. cv. HD 2329 and HUW 234) by supplimenting UV-B irradiation with different levels of mineral nutrients in order to evaluate the accumulation and translocation of trace elements. sUV-B significantly affected accumulation and translocation of most of the metals studied. Application of nutrients at higher doses enhanced the accumulation of trace elements in plants and grains of both cultivars. A higher dose of nutrient along with sUV-B resulted in increased accumulation of lead both in plants and grains, cadmium and chromium in grains, and copper in plants and decreased accumulation of cadmium in plants, copper in grains, chromium in plants and iron in plants and grains of both the tested cultivars. Nickel concentration increased in plants of HUW 234 due to simultaneous stress. Trace element concentration did not differ noticeably in the tested cultivars but the stress response differed perceptibly. Cultivar HD 2329 showed more significant interaction than HUW 234. PMID:24813006

  9. Trace element differentiation in ferruginous accumulation soil patterns under tropical rainforest of southern Cameroon, the role of climatic change.

    PubMed

    Temgoua, Emile; Pfeifer, Hans-Rudolf; Bitom, Dieudonné

    2003-03-01

    Regions under tropical rainforest cover, such as central Africa and Brazil are characterised by degradation and dismantling of old ferricrete structures. In southern Cameroon, these processes are relayed by present-day ferruginous accumulation soil facies, situated on the middle and the lower part of hill slopes. These facies become progressively harder towards the surface, containing from bottom to top, mainly kaolinite, kaolinite-goethite and Al-rich goethite-hematite, and are discontinuous to the relictic hematite-dominated ferricrete that exist in the upper part of the hill slope. These features were investigated in terms of geochemical differentiation of trace elements. It appears that, in contrast to the old ferricrete facies, the current ferruginous accumulations are enriched in transitional trace elements (V, Cr, Co, Y, Sc) and Pb, while alkali-earth elements are less differentiated. This recent chemical accumulation is controlled both by intense weathering of the granodiorite bedrock and by mobilisation of elements previously accumulated in the old ferricrete. The observed processes are clearly linked to the present-day humid climate with rising groundwater tables. They slowly replace the old ferricretes formed during Cretaceous time under more seasonal climatic conditions, representing an instructive case of continuos global change. PMID:12606160

  10. Accumulation of neurotoxic organochlorines and trace elements in brain of female European eel (Anguilla anguilla).

    PubMed

    Bonnineau, C; Scaion, D; Lemaire, B; Belpaire, C; Thomé, J-P; Thonon, M; Leermaker, M; Gao, Y; Debier, C; Silvestre, F; Kestemont, P; Rees, J-F

    2016-07-01

    Xenobiotics such as organochlorine compounds (OCs) and metals have been suggested to play a significant role in the collapse of European eel stocks in the last decades. Several of these pollutants could affect functioning of the nervous system. Still, no information is so far available on levels of potentially neurotoxic pollutants in eel brain. In present study, carried out on female eels caught in Belgian rivers and canals, we analyzed brain levels of potentially-neurotoxic trace elements (Ag, Al, As, Cd, Co, Cr, Cu, Fe, Hg, MeHg, Mn, Ni, Pb, Sn, Sb, Zn) and OCs (Polychlorinated biphenyls, PCBs; Hexachlorocyclohexanes, HCHs; Dichlorodiphenyltrichloroethane and its metabolites, DDTs). Data were compared to levels in liver and muscle tissues. Eel brain contained very high amounts of OCs, superior to those found in the two other tissues. Interestingly, the relative abundance of PCB congeners markedly differed between tissues. In brain, a predominance of low chlorinated PCBs was noted, whereas highly chlorinated congeners prevailed in muscle and liver. HCHs were particularly abundant in brain, which contains the highest amounts of β-HCH and ϒ-HCH. p,p'-DDTs concentration was similar between brain and muscle (i.e., about twice that of liver). A higher proportion of p,p'-DDT was noticed in brain. Except for Cr and inorganic Hg, all potentially neurotoxic metals accumulated in brain to levels equal to or lower than hepatic levels. Altogether, results indicate that eel brain is an important target for organic and, to a lesser extent, for inorganic neurotoxic pollutants. PMID:27376663

  11. Trace-element accumulation by Hygrohypnum ochraceum in the upper Rio Grande Basin, Colorado and New Mexico, USA

    SciTech Connect

    Carter, L.F.; Porter, S.D.

    1997-12-01

    Accumulation of 12 trace elements by transplanted aquatic bryophytes (Hygrohypnum ochraceum) was determined at 13 sites in the Rio Grande and tributary streams in southern Colorado and northern New Mexico as part of the US Geological Survey`s National Water-Quality Assessment Program. The purposes of the study were to determine the spatial distribution of trace elements in relation to land-use practices in the upper Rio Grande Basin, compare accumulation rates of metals in bryophytes at sites contaminated by trace elements, and evaluate transplanted aquatic bryophytes as a tool for examining the bioavailability of trace elements in relation to concentrations in water and bed sediment. Concentrations of Cd, Cu, Pb, and Zn in bryophytes, water, and bed sediment were significantly higher at sites that receive drainage from mining areas than at sites near agricultural or urban activities. Concentrations of most trace elements were lower in a tributary stream below an urban source than at sites near mining or agricultural use. Concentrations of Cu and Zn in bryophytes correlated with concentrations in water and bed sediment. In addition, bryophyte concentrations of As, Cd, and Pb correlated with concentrations in bed sediment. Transplanted bryophytes can provide an indication of bioavailability. Rates of accumulation were related to the magnitude of ambient trace-element concentrations; maximal uptake occurred during the first 10 d of exposure. Trace-element concentrations in transplanted bryophytes could potentially be used to predict water and sediment concentrations that represent an integration of conditions over short to intermediate lengths of time, rather than instantaneous conditions as measured using water samples.

  12. Decrease in air pollution load in urban environment of Bratislava (Slovakia) inferred from accumulation of metal elements in lichens.

    PubMed

    Guttová, Anna; Lackovičová, Anna; Pišút, Ivan; Pišút, Peter

    2011-11-01

    The study illustrates the response of epiphytic lichens to changing atmospheric conditions in Central Europe, where the emission of air pollutants has significantly decreased from 1990, in the area in and around Bratislava City. Variation in concentrations of seven metal elements (Cu, Cd, Cr, Mn, Ni, Pb and Zn) in the thalli of Evernia prunastri, Hypogymnia physodes and Parmelia sulcata is assessed. Samples of these species were exposed in lichen bags in 39 sites throughout the territory of the city (more than 300 km(2)) during the period December 2006-February 2007. The samples were analyzed by AAS for metal element contents prior to and after exposure. The decrease in air pollution (for all studied elements by more than 90%) corresponded to a decrease in the accumulation of elements in lichen thalli, e.g. the contents of Pb decreased by 69% and of Cd by 34% on average. The results show also variations in accumulation between with different lichen species. The background values of metal element contents in thalli of H. physodes growing in situ were measured in semi-natural sites in Slovakia. It is suggested that these can be used as a reference in large-scale monitoring studies in Central Europe. Analysis of compatible data from the current study, and the study performed at the end of 1990s shows a significant decrease of metal elements in the air pollution load. PMID:21327486

  13. Interactions between Cs, Sr, and other nutrients and trace element accumulation in Amaranthus shoot in response to variety effect.

    PubMed

    Chu, Qingnan; Watanabe, Toshihiro; Sha, Zhimin; Osaki, Mitsuru; Shinano, Takuro

    2015-03-01

    Aiming at clarifying the interactions between Cs, Sr, and other mineral elements in the genus Amaranthus, this study adopted 33 different varieties of Amaranthus and investigated the concentrations of 23 mineral elements in shoots grown in the fields of Iino in Fukushima prefecture. Significant varietal effects were detected for all elements except Se, and degree of interspecies variation was highly element dependent. Among 23 elements, amaranths were less sensitive to the accumulation of Cs and Sr than most other mineral elements to the species level. There are six elements showing significant correlation with Cs, positive correlations between As, Rb, Al, Fe, Ni, and Cs, and negative correlation between Ba and Cs. Significant correlations between Ca, Mg, Mn, Zn, B, Ba, Cd, and Sr were detected, and all of the coefficients were positive. Cs and Sr did not present significant correlation, but they were both significantly correlated with Ba. By principal component analysis (PCA), the first and second principal components (PC1 and PC2) accounted for 23.2 and 20.3% of the total variance and associated with Cs and Sr, respectively. Both of the two species took up more Cs by promoting the influx of elements positively correlated with Cs into shoot, but at the same time, Amaranthus hypochondriacus (L.) Mapes 847 decreased the K and Ba uptake and Amaranthus powellii (S. Wats) subsp. Powellii inhibited the accumulation of Rb, Sr, and significantly correlated elements of Sr in shoot. This study is the first to pave the way for comprehension on ionome in amaranth shoot at the variety level. The results of this research provide the ionomic basis for implementing countermeasures in the field against the translocation of Cs (and potentially Sr) toward crops and food. PMID:25660261

  14. Different Accumulation of Elements in Proximal and Distal Parts of the Left Anterior Descending Artery Beneath the Myocardial Bridge.

    PubMed

    Tohno, Yoshiyuki; Tohno, Setsuko; Minami, Takeshi; Pakdeewong-Ongkana, Nutcharin; Suwannahoy, Patipath; Quiggins, Ranida

    2016-05-01

    To elucidate the action of the myocardial bridge (MB) on the coronary artery, the authors first prepared the hearts with the MB located in the middle one third of the left anterior descending (LAD) artery and then investigated element accumulation in the LAD artery of the hearts with the MB by direct chemical analysis. Eighty-four formalin-fixed adult Thai hearts were dissected and the MBs were found in 39 of 84 hearts with a total of 44 MBs. The 37 MBs were located in the middle one third of the LAD artery. To examine the action of the MB on element accumulation in the LAD artery, the hearts with the MB which was located in the middle one third of the LAD artery and was longer than 1.5 cm were used as Materials. The left main coronary (LMC) and LAD arteries were removed from these hearts successively and the isolated arteries were divided into eight to ten segments. After incineration of arteries with nitric acid and perchloric acid, seven element contents of Ca, P, S, Mg, Zn, Fe, and Na were determined by inductively coupled plasma-atomic emission spectrometry. To examine the endothelial changes of the LAD artery, the inner surface of segments of the LAD artery was observed by scanning electron microscopy. It was found that the extent of accumulation of Ca, P, Zn, and Na was not uniform throughout the LAD artery and was higher in the proximal part than in the distal part with regard to the LAD artery beneath the MB (the tunneled LAD artery). The extent of accumulation of Ca, P, Zn, and Na in the proximal part of the tunneled LAD artery was similar to that in the segments proximal to the MB, whereas the extent of accumulation of Ca, P, Zn, and Na in the distal part of the tunneled LAD artery was similar to that in the segments distal to the MB. PMID:26343360

  15. Biodiversity of mineral nutrient and trace element accumulation in Arabidopsis thaliana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to grow on soils that vary widely in chemical composition, plants have evolved mechanisms for regulating the elemental composition of their tissues to balance the mineral nutrient and trace element bioavailability in the soil with the requirements of the plant for growth and development. T...

  16. Potentially toxic element contamination in soil and accumulation in maize plants in a smelter area in Kosovo.

    PubMed

    Nannoni, Francesco; Rossi, Sara; Protano, Giuseppe

    2016-06-01

    A biogeochemical field study was carried out in the industrial area of Kosovska Mitrovica in northern Kosovo, where agricultural soils were contaminated by potentially toxic elements due to smelting activity. Total and bioavailable contents of As, Cd, Co, Cu, Pb, Sb, U and Zn in soil and their concentrations in maize roots and grains were determined. Soil contamination by As, Cd, Cu, Pb, Sb and Zn was variable from slightly to highly contaminated soils and influenced both the bioavailable fraction and accumulation of these potentially toxic elements in maize tissues. The comparison between potentially toxic element concentrations in roots and grains indicated that maize is able to limit the transfer of non-essential elements to edible parts. The plant-to-soil bioconcentration indices suggested that the transfer of potentially toxic elements from soil to plant was predicted better by bioavailable concentrations than by the total contents. These indices further identified some competitions and interactions among these elements in root uptake and root-to-grain translocation. PMID:26961525

  17. Quantitative micro-PIXE comparison of elemental distribution in Ni-hyperaccumulating and non-accumulating genotypes of Senecio coronatus

    NASA Astrophysics Data System (ADS)

    Mesjasz-Przybyłowicz, J.; Przybyłowicz, W. J.; Prozesky, V. M.; Pineda, C. A.

    1997-07-01

    The Ni hyperaccumulator, plant species Senecio coronatus (Thunb.) Harv., Asteraceae is an example of plant adaptation mechanisms to different ecological conditions. This widespread species can inter alia be found on serpentine outcrops and the genotypes growing in serpentine soils show different ways of adaptation. The populations from two distant localities take up and translocate Ni in concentrations which are normally phytotoxic, while plants growing on a different site, in the vicinity of another hyperaccumulating species, absorb amounts which are typical for most of the plants found on serpentine soils. The NAC nuclear microprobe was used to compare the distribution of Ni and other elements in selected organs and cells with simultaneous use of PIXE and proton BackScattering (BS). Quantitative maps of stems showed large differences in concentrations and distributions of major and trace elements. In hyperaccumulating genotypes Ni is present everywhere within stem tissues, but the highest concentrations were found in the epidermis, cortex and phloem. In non-accumulating plants Ni was concentrated in the phloem. In the leaf epidermis Ni was concentrated in the cell walls for both accumulating and non-accumulating plants. These results suggest that biochemical diversity is more than morphological, because investigated genotypes belong to the same taxon.

  18. Evaluation of urban environment pollution based on the accumulation of macro- and trace elements in epiphytic lichens.

    PubMed

    Parzych, Agnieszka; Astel, Aleksander; Zduńczyk, Anna; Surowiec, Tomasz

    2016-01-01

    Nitrogen, phosphorus, potassium, magnesium, zinc, nickel, copper, manganese, iron and lead accumulation properties of three epiphytic lichen species (Hypogymnia physodes (L.) Nyl., Parmelia sulcata Taylor and Xanthoria parietina (L.) Th. Fr.) were compared. An assessment of pollution of the municipal environment in Słupsk (Poland) according to macro- and trace elements was also done. Lichen samples were taken in Autumn 2013 from Betula pendula, Fraxinus excelsior, Acer platanoides, A. pseudoplatanus and Populus sp. trees. Sampling stations comprised of house development areas, green urban parks, vicinity of streets with heavy traffic and industrial enterprises. It was found that lichens represent diverse accumulation properties to pollutants according to the species. X. parietina indicated the highest bioaccumulation in relation to N, K, Mg, Zn and Fe, the thalli of H. physodes accumulated the largest amounts of Ni and Pb, while P. sulcata P and Cu. Manganese was accumulated in similar quantities by all species. Evidences acquired by the use of factor analysis proved that pollution in Słupsk municipal environment is a serious issue with three major sources domination: street dust, marine factor and residual oil combustion. The high-risk areas were detected and visualized using surface maps based on Kriging algorithm. It was seen that the highest pollution occurs in the town centre, while the smallest happened on its outskirts and in urban parks. PMID:26745547

  19. An Untranslated cis-Element Regulates the Accumulation of Multiple C4 Enzymes in Gynandropsis gynandra Mesophyll Cells[OPEN

    PubMed Central

    Burgess, Steven J.; Reyna-Llorens, Ivan; Knerova, Jana; Stanley, Susan

    2016-01-01

    C4 photosynthesis is a complex phenotype that allows more efficient carbon capture than the ancestral C3 pathway. In leaves of C4 species, hundreds of transcripts increase in abundance compared with C3 relatives and become restricted to mesophyll (M) or bundle sheath (BS) cells. However, no mechanism has been reported that regulates the compartmentation of multiple enzymes in M or BS cells. We examined mechanisms regulating CARBONIC ANHYDRASE4 (CA4) in C4 Gynandropsis gynandra. Increased abundance is directed by both the promoter region and introns of the G. gynandra gene. A nine-nucleotide motif located in the 5′ untranslated region (UTR) is required for preferential accumulation of GUS in M cells. This element is present and functional in three additional 5′ UTRs and six 3′ UTRs where it determines accumulation of two isoforms of CA and pyruvate,orthophosphate dikinase in M cells. Although the GgCA4 5′ UTR is sufficient to direct GUS accumulation in M cells, transcripts encoding GUS are abundant in both M and BS. Mutating the GgCA4 5′ UTR abolishes enrichment of protein in M cells without affecting transcript abundance. The work identifies a mechanism that directs cell-preferential accumulation of multiple enzymes required for C4 photosynthesis. PMID:26772995

  20. Trace element accumulation in relation to trophic niches of shorebirds using intertidal mudflats

    NASA Astrophysics Data System (ADS)

    Lucia, Magali; Bocher, Pierrick; Chambosse, Mélanie; Delaporte, Philippe; Bustamante, Paco

    2014-09-01

    This study investigated the link between trace element concentrations and respective diets of two shorebird species present in the Pertuis Charentais, Atlantic coast of France: the Dunlin (Calidris alpina) and Redshank (Tringa totanus). Trace element concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Zn) were investigated in the liver, kidney, muscle and feathers of 28 dunlins and 15 redshanks accidentally dead during catches by mist net. Analyses of carbon and nitrogen stable isotope ratios were carried out in liver, muscle and feathers to determine whether differences in diet explained the variations in elemental levels. These results were compared to previous data obtained on two other shorebird species present on the same sites: the Black-tailed Godwit (Limosa limosa) and the Red Knot (Calidris canutus). This study demonstrated that shorebirds of the Pertuis Charentais were characterized by differential trace element bioaccumulation. Arsenic and Se concentrations in internal tissues were elevated in red knots and dunlins, whereas redshanks displayed higher Cd concentrations. These trace element bioaccumulation discrepancies could mainly come from divergences of trophic habits between shorebirds. Species with the highest trophic position displayed the highest Hg concentrations in the liver, muscle and feathers demonstrating therefore the biomagnification potential of this metal, as opposed to Cd and Pb. The same trend was observed in muscle and feathers for Se and only in feathers for As. These data highlighted the need to study several tissues to obtain a full comprehension of trace element exposure and pathways especially for long-distance migrating species using various habitats and sites.

  1. Accumulation and sub-cellular partitioning of metals and As in the clam Venerupis corrugata: Different strategies towards different elements.

    PubMed

    Velez, Cátia; Figueira, Etelvina; Soares, Amadeu M V M; Freitas, Rosa

    2016-08-01

    The main goal of the present study was to assess accumulation, tolerance and sub-cellular partitioning of As, Hg, Cd and Pb in Venerupis corrugata. Results showed an increase of elements accumulation in V. corrugata with the increase of exposure. However, organisms presented higher capacity to accumulate Hg, Cd and Pb (BCF ≥ 12.8) than As (BCF ≤ 2.1) and higher accumulation rate for Cd and Pb than for Hg and As. With the increase of Hg exposure concentrations clams tended to increase the amount of metal bound to metal-sensitive fractions, which may explain the mortality recorded at the highest exposure concentration. Cd sub-cellular partitioning showed that with the increase of exposure concentrations V. corrugata increased the amount of metal in the cellular debris fraction, probably bound to the cellular membranes which explain the mortality recorded at the highest concentration. Results on As partitioning demonstrated that most of the metalloid was associated with fractions in the biologically detoxified metal compartment (BDM). Since high mortality was observed in clams exposed to As our results may indicate that this strategy was not enough to prevent clams from toxic effects and mortality occurred. When exposed to Pb most of the metal was in the BDM compartment, but in this case the metal was mostly in the metal-rich granules fraction which seemed to be efficient in preventing clams from toxicity, and no mortality was recorded. Our study further revealed that As and Hg were the most available elements to be biomagnified through the food chain. PMID:27174825

  2. Rice tissue accumulation of particular elements is dependent on the plant’s physiology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The leaves, grain and other parts of a rice plant require mineral nutrients for various metabolic and other physiological functions. Breeders sometimes want to manipulate the element composition of the grain. Nutrient-dense grain, which is primarily seen as a means for improving nutrition in some co...

  3. Field study on the accumulation of trace elements by vegetables produced in the vicinity of abandoned pyrite mines.

    PubMed

    Alvarenga, Paula; Simões, Isabel; Palma, Patrícia; Amaral, Olga; Matos, João Xavier

    2014-02-01

    To evaluate the accumulation of trace elements (TE) by vegetables produced in the vicinity of abandoned pyrite mines, eighteen different small farms were selected near three mines from the Portuguese sector of the Iberian Pyrite Belt (São Domingos, Aljustrel and Lousal). Total and bioavailable As, Cu, Pb, and Zn concentrations were analyzed in the soils, and the same TE were analyzed in three different vegetables, lettuce (Lactuca sativa), coriander (Coriandrum sativum), and cabbage (Brassica oleracea), collected at the same locations. The soils were contaminated with As, Cu, Pb, and Zn, since their total concentrations exceeded the considered soil quality guideline values for plant production in the majority of the sampling sites. The maximum total concentrations for those TE were extremely high in some of the sampling sites (e.g. 1,851 mg As kg(-1) in São Domingos, 1,126 mg Cu kg(-1) in Aljustrel, 4,946 mg Pb kg(-1) in São Domingos, and 1,224 mg Zn kg(-1) in Aljustrel). However, the soils were mainly circumneutral, a factor that contributes to their low bioavailable fractions. As a result, generally, the plants contained levels of these elements characteristic of uncontaminated plants, and accumulation factors for all elements <1, typical of excluder plants. Furthermore, the estimated daily intake (EDI) for Cu and Zn, through the consumption of these vegetables, falls below the recommended upper limit for daily intake of these elements. The sampling site that stood out from the others was located at São João de Negrilhos (Aljustrel), where bioavailable Zn levels were higher, a consequence of the slight acidity of the soil. Therefore, the Zn content in vegetables was also higher, characteristic of contaminated plants, emphasizing the risk of Zn entering the human food chain via the consumption of crops produced on those soils. PMID:24252198

  4. Avian retroviral RNA element promotes unspliced RNA accumulation in the cytoplasm.

    PubMed Central

    Ogert, R A; Lee, L H; Beemon, K L

    1996-01-01

    All retroviruses need mechanisms for nucleocytoplasmic export of their unspliced RNA and for maintenance of this RNA in the cytoplasm, where it is either translated to produce Gag and Pol proteins or packaged into viral particles. The complex retroviruses encode Rev or Rex regulatory proteins, which interact with cis-acting viral sequences to promote cytoplasmic expression of incompletely spliced viral RNAs. Since the simple retroviruses do not encode regulatory proteins, we proposed that they might contain cis-acting sequences that could interact with cellular Rev-like proteins. To test this possibility, we initially looked for a cis-acting sequence in avian retroviruses that could substitute for Rev and the Rev response element in human immunodeficiency virus type 1 expression constructs. A cis-acting element in the 3' untranslated region of Rous sarcoma virus (RSV) RNA was found to promote Rev-independent expression of human immunodeficiency virus type 1 Gag proteins. This element was mapped between RSV nucleotides 8770 and 8925 and includes one copy of the direct repeat (DR) sequences flanking the RSV src gene; similar activity was observed for the upstream DR. To address the function of this element in RSV, both copies of the DR sequence were deleted. Subsequently, each DR sequence was inserted separately back into this deleted construct. While the viral construct lacking both DR sequences failed to replicate, constructs containing either the upstream or downstream DR replicated well. In the absence of both DRs, Gag protein levels were severely diminished and cytoplasmic levels of unspliced viral RNA were significantly reduced; replacement of either DR sequence led to normal levels of Gag protein and cytoplasmic unspliced RNA. PMID:8648719

  5. Accumulation of trace elements and growth responses in Corbicula fluminea downstream of a coal-fired power plant

    SciTech Connect

    Peltier, G.L.; Wright, M.S.; Hopkins, W.A.; Meyer, J.L.

    2009-07-15

    Lentic organisms exposed to coal-fired power plant (CFPP) discharges can have elevated trace element concentrations in their tissues, but this relationship and its potential consequences are unclear for lotic organisms. To explore these patterns in a lotic environment, we transplanted Corbicula fluminea from a reference stream to a stream receiving CFPP discharge. We assessed trace element accumulation and glutathione concentration in clam tissue, shell growth, and condition index at five sites along a contamination gradient. Clams at the most upstream and contaminated site had the highest growth rate, condition index, glutathione concentrations, and concentrations of arsenic (7.85 {+-} 0.25 {mu} g/g (dry mass)), selenium (17.75 {+-} 0.80 {mu} g/g), and cadmium (7.28 {+-} 0.34 {mu} g/g). Mercury concentrations declined from 4.33 {+-} 0.83 to 0.81 {+-} 0.11 {mu} g/g (dry mass) in clams transplanted into the selenium-rich environment nearest the power plant, but this effect was not as evident at less impacted, downstream sites. Even though dilution of trace elements within modest distances from the power plant reduced bioaccumulation potential in clams, long-term loading of trace elements to downstream depositional regions (e.g., slow moving, silty areas) is likely significant.

  6. Accumulation of chemical elements in the raised peatbogs of the subtaiga Trans-Urals in the Holocene

    NASA Astrophysics Data System (ADS)

    Larina, N. S.; Larin, S. I.; Merkushina, G. A.

    2014-07-01

    The results of studying the variability of the geochemical parameters of the layers of the Sartamskii upland peatbog in the south of Tyumen oblast based on the radiocarbon time scale are given. Four basic types of peat and stages of peat deposits formation in the Holocene are distinguished: the organomineral layer of the sediments in a paleolake (up to 5065 ± 60 years ago), the low moor layer (4300-4900 years ago), the transitional layer (3100-4300 years ago), and the high moor peat (250-3100 years ago). The upper peat layer (last 200-300 years) significantly differs from its main portion; in particular, it is characterized by an increased ash content and the accumulation of a number of elements. The relationship between the various characteristics of the deposit is analyzed using principal component analysis, and the conditions of the formation of the peat deposit in different time periods are estimated, including the climatic conditions (in relative units). The anthropogenic signal of the accumulation of some elements in wetland systems is identified.

  7. Trace element accumulation and trophic relationships in aquatic organisms of the Sundarbans mangrove ecosystem (Bangladesh).

    PubMed

    Borrell, Asunción; Tornero, Victoria; Bhattacharjee, Dola; Aguilar, Alex

    2016-03-01

    The Sundarbans forest is the largest and one of the most diverse and productive mangrove ecosystems in the world. Located at the northern shoreline of the Bay of Bengal in the Indian Ocean and straddling India and Bangladesh, the mangrove forest is the result of three primary river systems that originate further north and northwest. During recent decades, the Sundarbans have been subject to increasing pollution by trace elements caused by the progressive industrialization and urbanization of the basins of these three rivers. As a consequence, animals and plants dwelling downstream in the mangroves are exposed to these pollutants in varying degrees, and may potentially affect human health when consumed. The aim of the present study was to analyse the concentrations of seven trace elements (Zn, Cu, Cr, Hg, Pb, Cd and As) in 14 different animal and plant species collected in the Sundarbans in Bangladesh to study their transfer through the food web and to determine whether their levels in edible species are acceptable for human consumption. δ(15)N values were used as a proxy of the trophic level. A decrease in Zn, Cu, Pb and Cd levels was observed with increasing trophic position. Trace element concentrations measured in all organisms were, in general, lower than the concentrations obtained in other field studies conducted in the same region. When examined with respect to accepted international standards, the concentrations observed in fish and crustaceans were generally found to be safe for human consumption. However, the levels of Zn in Scylla serrata and Cr and Cd in Harpadon nehereus exceeded the proposed health advisory levels and may be of concern for human health. PMID:26748006

  8. Tricholoma matsutake can absorb and accumulate trace elements directly from rock fragments in the shiro.

    PubMed

    Vaario, Lu-Min; Pennanen, Taina; Lu, Jinrong; Palmén, Jorma; Stenman, Jarkko; Leveinen, Jussi; Kilpeläinen, Petri; Kitunen, Veikko

    2015-07-01

    Tricholoma matsutake, a highly valued delicacy in Japan and East Asia, is an ectomycorrhizal fungus typically found in a complex soil community of mycorrhizae, soil microbes, and host-tree roots referred to as the shiro in Japan. A curious characteristic of the shiro is an assortment of small rock fragments that have been implicated as a direct source of minerals and trace elements for the fungus. In this study, we measured the mineral content of 14 samples of shiro soil containing live matsutake mycelium and the extent to which the fungus can absorb minerals directly from the rock fragments. X-ray powder diffraction identified major phases of quartz, microcline, orthoclase, and albite in all shiro samples. PCR-denaturing gradient gel electrophoresis (DGGE) fingerprinting and direct sequencing confirmed the presence of T. matsutake on 32 of 33 rock fragments. Piloderma sp. co-occurred on 40% of fragments and was positively correlated with locations known to produce good mushroom crops. The ability of T. matsutake to absorb trace elements directly from rock fragments was examined in vitro on nutrient-agar plates supplemented with rock fragments from the shiro. In comparison to the mineral content of tissues grown on control media, the concentration of Al, Cu, Fe, Mn, P, and Zn increased from 1.1 to 106.4 times for both T. matsutake and Piloderma sp. Mineral content of dried sporocarps sampled from the study site partially reflected the results of the in vitro study. We discuss the implications of our results with respect to the natural development and artificial culture of this important fungus. PMID:25355073

  9. The effects of copper, manganese and zinc on plant growth and elemental accumulation in the manganese-hyperaccumulator Phytolacca americana.

    PubMed

    Zhao, Huijun; Wu, Liangqi; Chai, Tuanyao; Zhang, Yuxiu; Tan, Jinjuan; Ma, Shengwen

    2012-09-01

    Synchrotron radiation X-ray fluorescence (SRXRF) and inductively coupled plasma mass spectrometry were used to estimate major, minor and trace elements in Cu-, Zn- and Mn-treated Phytolacca americana. The effects of the addition of Cu, Zn and Mn on morphological parameters, such as root length, shoot height, and fresh and dry weights of shoots and roots, were also examined. In addition, the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidases (GPX) and catalase (CAT) and the expression of Fe-SOD, Cu/Zn-SOD, metallothionein-2 and glutathione S-transferase (GST) exposed to the highest amounts of Cu, Zn or Mn were detected. Our results confirmed the following: (1) Zn supplementation leads to chlorosis, disturbed elemental homeostasis and decreased concentrations of micro- and macroelements such as Fe, Mg, Mn, Ca and K. Cu competed with Fe, Mn and Zn uptake in plants supplemented with 25 μM Cu. However, no antagonistic interactions took place between Cu, Zn, Mn and Fe uptake in plants supplemented with 100 μM Cu. Mn supplementation at various concentrations had no negative effects on elemental deficits. Mn was co-located with high concentrations of Fe and Zn in mature leaves and the concentrations of macro elements were unchanged. (2) P. americana supplemented with increased concentrations of Zn and Cu exhibited lower biomass production and reduced plant growth. (3) When plants were supplemented with the highest Zn and Cu concentrations, symptoms of toxicity corresponded to decreased SOD or CAT activities and increased APX and GPX activities. However, Mn tolerance corresponded to increased SOD and CAT activities and decreased POD and APX activities. Our study revealed that heavy metals partially exert toxicity by disturbing the nutrient balance and modifying enzyme activities that induce damage in plants. However, P. americana has evolved hyper accumulating mechanisms to maintain elemental balance and redox homeostasis under

  10. Fractionation mechanisms of rare earth elements (REEs) in hydroponic wheat: an application for metal accumulation by plants.

    PubMed

    Ding, Shiming; Liang, Tao; Zhang, Chaosheng; Huang, Zechun; Xie, Yaning; Chen, Tongbin

    2006-04-15

    Fractionations of rare earth elements (REEs) in wheat (Triticum aestivum L.) were observed through application of exogenous mixed REEs under hydroponic conditions. Middle REE (MREE), light REE (LREE), and heavy REE (HREE) enrichments were found in roots, stems, and leaves, respectively, accompanied by the tetrad effect (an effect that can cause a split of REE patterns into four consecutive segments) in these organs. Investigations into REE speciation in roots and in the xylem sap with X-ray absorption spectroscopy (XAS) and nanometer-sized TiO2 adsorption techniques, associated with other controlled experiments, demonstrated that REE fractionations in wheat were caused by the combined effects of chemical precipitation, cell wall absorption, and solution complexation by organic ligands in the xylem vessels. REE fractionations in wheat, which were derived from the small differences of chemical properties across REE series, may reflect a sensitive internal chemical environment that influences plant accumulation for REEs and their analogues actinide radionuclides. PMID:16683609

  11. The accumulation of elements in plants growing spontaneously on small heaps left by the historical Zn-Pb ore mining.

    PubMed

    Stefanowicz, Anna M; Stanek, Małgorzata; Woch, Marcin W; Kapusta, Paweł

    2016-04-01

    The study evaluated the levels of nine metals, namely Ca, Cd, Fe, K, Mg, Mn, Pb, Tl, and Zn, in soils and tissues of ten plant species growing spontaneously on heaps left by historical mining for Zn-Pb ores. The concentrations of Cd, Pb, Tl, and Zn in heap soils were much higher than in control soils. Plants growing on heaps accumulated excessive amounts of these elements in tissues, on average 1.3-52 mg Cd kg(-1), 9.4-254 mg Pb kg(-1), 0.06-23 mg Tl kg(-1) and 134-1479 mg Zn kg(-1) in comparison to 0.5-1.1 mg Cd kg(-1), 2.1-11 mg Pb kg(-1), 0.02-0.06 mg Tl kg(-1), and 23-124 mg Zn kg(-1) in control plants. The highest concentrations of Cd, Pb, and Zn were found in the roots of Euphorbia cyparissias, Fragaria vesca, and Potentilla arenaria, and Tl in Plantago lanceolata. Many species growing on heaps were enriched in K and Mg, and depleted in Ca, Fe, and Mn. The concentrations of all elements in plant tissues were dependent on species, organ (root vs. shoot), and species-organ interactions. Average concentrations of Ca, K, and Mg were generally higher in shoots than in roots or similar in the two organs, whereas Cd, Fe, Pb, Tl, and Zn were accumulated predominantly in the roots. Our results imply that heaps left by historical mining for Zn-Pb ores may pose a potential threat to the environment and human health. PMID:26635220

  12. Element accumulation in boreal bryophytes, lichens and vascular plants exposed to heavy metal and sulfur deposition in Finland.

    PubMed

    Salemaa, Maija; Derome, John; Helmisaari, Heljä-Sisko; Nieminen, Tiina; Vanha-Majamaa, Ilkka

    2004-05-25

    Macronutrient (N, P, K, Mg, S, Ca), heavy metal (Fe, Zn, Mn, Cu, Ni, Cd, Pb) and Al concentrations in understorey bryophytes, lichens and vascular plant species growing in Scots pine forests at four distances from the Harjavalta Cu-Ni smelter (0.5, 2, 4 and 8 km) were compared to those at two background sites in Finland. The aim was to study the relationship between element accumulation and the distribution of the species along a pollution gradient. Elevated sulfur, nitrogen and heavy metal concentrations were found in all species groups near the pollution source. Macronutrient concentrations tended to decrease in the order: vascular plants>bryophytes>lichens, when all the species groups grew on the same plot. Heavy metal concentrations (except Mn) were the highest in bryophytes, followed by lichens, and were the lowest in vascular plants. In general, vascular plants, being capable of restricting the uptake of toxic elements, grew closer to the smelter than lichens, while bryophytes began to increase in the understorey vegetation at further distances from the smelter. A pioneer moss (Pohlia nutans) was an exception, because it accumulated considerably higher amounts of Cu and Ni than the other species and still survived close to the smelter. The abundance of most of the species decreased with increasing Cu and Ni concentrations in their tissues. Cetraria islandica, instead, showed a positive relationship between the abundance and Cu, Ni and S concentrations of the thallus. It is probable that, in addition to heavy metals, sporadically high SO(2) emissions have also affected the distribution of the plant species. PMID:15081702

  13. Differential patterns of accumulation and retention of dietary trace elements associated with coal ash during larval development and metamorphosis of an amphibian.

    PubMed

    Heyes, Andrew; Rowe, Christopher L; Conrad, Phillip

    2014-01-01

    We performed an experiment in which larval gray tree frogs (Hyla chrysoscelis) were raised through metamorphosis on diets increased with a suite of elements associated with coal combustion residues (silver [Ag], arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], mercury [Hg], lead [Pb], selenium [Se], vanadium [V], and zinc [Zn]) at "low" and "high" concentrations. We quantified accumulation of metals at three life stages (mid-larval development, initiation of metamorphosis, and completion of metamorphosis) as well as effects on survival, metabolic rate, size at metamorphosis, and duration and loss of weight during metamorphosis. Most elements were accumulated in a dose-dependent pattern by some or all life stages, although this was not the case for Hg. For most elements, larval body burdens exceeded those of later life stages in some or all treatments (control, low, or high). However for Se, As, and Hg, body burdens in control and low concentrations were increased in later compared with earlier life stages. A lack of dose-dependent accumulation of Hg suggests that the presence of high concentrations of other elements (possibly Se) either inhibited accumulation or increased depuration of Hg. The duration of metamorphosis (forelimb emergence through tail resorption) was lengthened in individuals exposed to the highest concentrations of elements, but there were no other statistically significant biological effects. This study shows that patterns of accumulation and possibly depuration of metals and trace elements are complex in animals possessing complex life cycles. Further study is required to determine specific interactions affecting these patterns, in particular which elements may be responsible for affecting accumulation or retention of Hg when organisms are exposed to complex mixtures of elements. PMID:24169791

  14. Effects of ocean acidification on trace element accumulation in the early-life stages of squid Loligo vulgaris.

    PubMed

    Lacoue-Labarthe, T; Réveillac, E; Oberhänsli, F; Teyssié, J L; Jeffree, R; Gattuso, J P

    2011-09-01

    The anthropogenic release of carbon dioxide (CO(2)) into the atmosphere leads to an increase in the CO(2) partial pressure (pCO(2)) in the ocean, which may reach 950 μatm by the end of the 21st century. The resulting hypercapnia (high pCO(2)) and decreasing pH ("ocean acidification") are expected to have appreciable effects on water-breathing organisms, especially on their early-life stages. For organisms like squid that lay their eggs in coastal areas where the embryo and then paralarva are also exposed to metal contamination, there is a need for information on how ocean acidification may influence trace element bioaccumulation during their development. In this study, we investigated the effects of enhanced levels of pCO(2) (380, 850 and 1500 μatm corresponding to pH(T) of 8.1, 7.85 and 7.60) on the accumulation of dissolved (110m)Ag, (109)Cd, (57)Co, (203)Hg, (54)Mn and (65)Zn radiotracers in the whole egg strand and in the different compartments of the egg of Loligo vulgaris during the embryonic development and also in hatchlings during their first days of paralarval life. Retention properties of the eggshell for (110m)Ag, (203)Hg and (65)Zn were affected by the pCO(2) treatments. In the embryo, increasing seawater pCO(2) enhanced the uptake of both (110m)Ag and (65)Zn while (203)Hg showed a minimum concentration factor (CF) at the intermediate pCO(2). (65)Zn incorporation in statoliths also increased with increasing pCO(2). Conversely, uptake of (109)Cd and (54)Mn in the embryo decreased as a function of increasing pCO(2). Only the accumulation of (57)Co in embryos was not affected by increasing pCO(2). In paralarvae, the CF of (110m)Ag increased with increasing pCO(2), whereas the (57)Co CF was reduced at the highest pCO(2) and (203)Hg showed a maximal uptake rate at the intermediate pCO(2). (54)Mn and (65)Zn accumulation in paralarvae were not significantly modified by hypercapnic conditions. Our results suggest a combined effect of pH on the adsorption and

  15. The spatial distribution, accumulation and potential source of seldom monitored trace elements in sediments of Three Gorges Reservoir, China

    NASA Astrophysics Data System (ADS)

    Han, Lanfang; Gao, Bo; Zhou, Huaidong; Xu, Dongyu; Wei, Xin; Gao, Li

    2015-11-01

    The alteration of hydrologic condition of Three Gorges Reservoir (TGR) after impoundment has caused numerous environmental changes. This study investigated the distribution, accumulation and potential sources of the seldom monitored trace elements (SMTEs) in sediments from three tributaries (ZY, MX and CT) and one mainstream (CJ) in TGR during different seasons. The average contents of most SMTEs excluding Sb in the winter were similar to that in the summer. For Sb, its average concentrations in the summer and winter were roughly six and three times higher than its background value, respectively. Contamination factor (CF) and geoaccumulation index (Igeo) demonstrated that most of the sediments were obviously contaminated by Sb. The enrichment factors (EF) of Ga and Sb were higher than 2.0, revealing the possible anthropogenic inputs; However, the EFs of other SMTEs were lower than 1.5, indicating the natural inputs. Correlation and principal component analysis suggested the most SMTEs were positively correlated with major elements (Cr, Mn, Cu, Zn, As, Cd and Pb) and clay contents, which implies that SMTEs had the same sources with these major metals, and the fine particles might be a major carrier for transporting SMTEs from the rivers to the TGR.

  16. The spatial distribution, accumulation and potential source of seldom monitored trace elements in sediments of Three Gorges Reservoir, China

    PubMed Central

    Han, Lanfang; Gao, Bo; Zhou, Huaidong; Xu, Dongyu; Wei, Xin; Gao, Li

    2015-01-01

    The alteration of hydrologic condition of Three Gorges Reservoir (TGR) after impoundment has caused numerous environmental changes. This study investigated the distribution, accumulation and potential sources of the seldom monitored trace elements (SMTEs) in sediments from three tributaries (ZY, MX and CT) and one mainstream (CJ) in TGR during different seasons. The average contents of most SMTEs excluding Sb in the winter were similar to that in the summer. For Sb, its average concentrations in the summer and winter were roughly six and three times higher than its background value, respectively. Contamination factor (CF) and geoaccumulation index (Igeo) demonstrated that most of the sediments were obviously contaminated by Sb. The enrichment factors (EF) of Ga and Sb were higher than 2.0, revealing the possible anthropogenic inputs; However, the EFs of other SMTEs were lower than 1.5, indicating the natural inputs. Correlation and principal component analysis suggested the most SMTEs were positively correlated with major elements (Cr, Mn, Cu, Zn, As, Cd and Pb) and clay contents, which implies that SMTEs had the same sources with these major metals, and the fine particles might be a major carrier for transporting SMTEs from the rivers to the TGR. PMID:26538153

  17. The spatial distribution, accumulation and potential source of seldom monitored trace elements in sediments of Three Gorges Reservoir, China.

    PubMed

    Han, Lanfang; Gao, Bo; Zhou, Huaidong; Xu, Dongyu; Wei, Xin; Gao, Li

    2015-01-01

    The alteration of hydrologic condition of Three Gorges Reservoir (TGR) after impoundment has caused numerous environmental changes. This study investigated the distribution, accumulation and potential sources of the seldom monitored trace elements (SMTEs) in sediments from three tributaries (ZY, MX and CT) and one mainstream (CJ) in TGR during different seasons. The average contents of most SMTEs excluding Sb in the winter were similar to that in the summer. For Sb, its average concentrations in the summer and winter were roughly six and three times higher than its background value, respectively. Contamination factor (CF) and geoaccumulation index (Igeo) demonstrated that most of the sediments were obviously contaminated by Sb. The enrichment factors (EF) of Ga and Sb were higher than 2.0, revealing the possible anthropogenic inputs; However, the EFs of other SMTEs were lower than 1.5, indicating the natural inputs. Correlation and principal component analysis suggested the most SMTEs were positively correlated with major elements (Cr, Mn, Cu, Zn, As, Cd and Pb) and clay contents, which implies that SMTEs had the same sources with these major metals, and the fine particles might be a major carrier for transporting SMTEs from the rivers to the TGR. PMID:26538153

  18. Universal dependence of hydrogen oxidation and evolution reaction activity of platinum-group metals on pH and hydrogen binding energy

    PubMed Central

    Zheng, Jie; Sheng, Wenchao; Zhuang, Zhongbin; Xu, Bingjun; Yan, Yushan

    2016-01-01

    Understanding how pH affects the activity of hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) is key to developing active, stable, and affordable HOR/HER catalysts for hydroxide exchange membrane fuel cells and electrolyzers. A common linear correlation between hydrogen binding energy (HBE) and pH is observed for four supported platinum-group metal catalysts (Pt/C, Ir/C, Pd/C, and Rh/C) over a broad pH range (0 to 13), suggesting that the pH dependence of HBE is metal-independent. A universal correlation between exchange current density and HBE is also observed on the four metals, indicating that they may share the same elementary steps and rate-determining steps and that the HBE is the dominant descriptor for HOR/HER activities. The onset potential of CO stripping on the four metals decreases with pH, indicating a stronger OH adsorption, which provides evidence against the promoting effect of adsorbed OH on HOR/HER. PMID:27034988

  19. Levels of platinum group metals in selected species (Sarotherodon melanotheron, Chonophorus lateristriga, Macrobrachium vollenhovenii and Crassostrea tulipa) in some estuaries and lagoons along the coast of Ghana.

    PubMed

    Essumang, D K; Adokoh, C K; Boamponsem, L

    2010-01-01

    The use of some biota as bioindicators of heavy metal pollution has been demonstrated as particularly adequate due to their capacity of bioconcentration. This study evaluated the levels of platinum group metals (PGMs) in some selected species along the coastal belt of Ghana, using the neutron activation analysis (NAA) method. The result was processed to evaluate pollution indices in order to map the distribution of the metals in those species in the lagoons and estuaries along the costal belt of Ghana. The analysis showed significant levels of all PGMs in blackchin tilapia (Sarotherodon melanotheron Cichlidae), brown goby (Chonophorus lateristriga Gobiidae), shrimp (Macrobrachium vollenhovenii Palaemonidae), and mangrove oysters (Crassostrea tulipa Ostreidae) in the lagoons and river Pra estuary. However, the oysters showed an elevated mean concentration of 0.13 μg/g (dry weight) Pd. From the pollution indices, most of the sampling sites registered mean contamination factor (CF) values between 1.20 and 3.00 for Pt, Pd, and Rh. The pollution load index (PLI) conducted also gave an average pollution index between 0.79 and 2.37, indicating progressive contamination levels. The results revealed that anthropogenic sources, industrial and hospital effluent, etc., together with vehicular emissions, could be the contributing factors to the deposition of PGMs along the Ghanaian coast. PMID:20953547

  20. Universal dependence of hydrogen oxidation and evolution reaction activity of platinum-group metals on pH and hydrogen binding energy.

    PubMed

    Zheng, Jie; Sheng, Wenchao; Zhuang, Zhongbin; Xu, Bingjun; Yan, Yushan

    2016-03-01

    Understanding how pH affects the activity of hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) is key to developing active, stable, and affordable HOR/HER catalysts for hydroxide exchange membrane fuel cells and electrolyzers. A common linear correlation between hydrogen binding energy (HBE) and pH is observed for four supported platinum-group metal catalysts (Pt/C, Ir/C, Pd/C, and Rh/C) over a broad pH range (0 to 13), suggesting that the pH dependence of HBE is metal-independent. A universal correlation between exchange current density and HBE is also observed on the four metals, indicating that they may share the same elementary steps and rate-determining steps and that the HBE is the dominant descriptor for HOR/HER activities. The onset potential of CO stripping on the four metals decreases with pH, indicating a stronger OH adsorption, which provides evidence against the promoting effect of adsorbed OH on HOR/HER. PMID:27034988

  1. Platinum-group elements in southern Africa: mineral inventory and an assessment of undiscovered mineral resources: Chapter Q in Global mineral resource assessment

    USGS Publications Warehouse

    Zientek, Michael L.; Causey, J. Douglas; Parks, Heather L.; Miller, Robert J.

    2014-01-01

    The large layered intrusions in southern Africa—the Bushveld Complex and the Great Dyke—are now and will continue to be a major source of the world’s supply of PGE. Mining will not deplete the identified mineral resources and reserves or potential undiscovered mineral resources for many decades; however, in the near-term, PGE supply could be affected by social, environmental, political, and economic factors.

  2. Assessment of metallic mineral resources in the Humboldt River Basin, Northern Nevada, with a section on Platinum-Group-Element (PGE) Potential of the Humboldt Mafic Complex

    USGS Publications Warehouse

    Wallace, Alan R.; Ludington, Steve; Mihalasky, Mark J.; Peters, Stephen G.; Theodore, Ted G.; Ponce, David A.; John, David A.; and Berger, Byron R.; Zientek, Michael L.; Sidder, Gary B.; Zierenberg, Robert A.

    2004-01-01

    The Humboldt River Basin is an arid to semiarid, internally drained basin that covers approximately 43,000 km2 in northern Nevada. The basin contains a wide variety of metallic and nonmetallic mineral deposits and occurrences, and, at various times, the area has been one of the Nation's leading or important producers of gold, silver, copper, mercury, and tungsten. Nevada currently (2003) is the third largest producer of gold in the world and the largest producer of silver in the United States. Current exploration for additional mineral deposits focuses on many areas in northern Nevada, including the Humboldt River Basin.

  3. Zoning of platinum group mineral assemblages in the UG2 chromitite determined through in situ SEM-EDS-based image analysis

    NASA Astrophysics Data System (ADS)

    Voordouw, Ronald J.; Gutzmer, Jens; Beukes, Nicolas J.

    2010-02-01

    In situ scanning electron microscopy-energy dispersive X-ray spectrometry analysis of platinum group minerals (PGM) and base metal sulfides in the UG2 chromitite shows that this ore body is zoned along at least ˜6 km of strike. The uppermost part of the UG2 chromitite, referred to as the leader seam, is ˜16 cm thick and has a PGM assemblage that is dominated by PGE arsenides, sulpho-arsenides, and alloys (˜70 vol.% of all PGM), which are typical secondary PGM assemblages in other segments of UG2. This is the first time such laterally persistent secondary assemblages have been identified in the UG2 chromitite, as previously, they were only known to occur adjacent to transgressive fluid-bearing structures (e.g., pipes, faults). The underlying main seam is thicker (one to nine seams totaling ˜130 cm) and has a PGM assemblage that consists mostly of Pt sulfide, Pt-Pd sulfide, Pt-Rh-Cu sulfide, laurite, and Fe-Pt alloys (˜85 vol.% of all PGM), typically regarded as primary magmatic constituents of UG2 chromitite. There are, however, some subtle vertical changes in the PGM assemblages of the main seam that include the occasional presence of secondary assemblages in the top and bottom parts. The origin of these secondary PGM assemblages is related to alteration by hydrothermal fluids and/or fluid-rich melts that infiltrated during crystallization of the UG2 and may possibly have been derived from the UG2 chromitite itself.

  4. Species classification and bioactive ingredients accumulation of BaiJiangCao based on characteristic inorganic elements analysis by inductively coupled plasma-mass spectrometry and multivariate analysis

    PubMed Central

    Wen-Lan, Li; Xue, Zhang; Xin-Xin, Yang; Shuai, Wang; Lin, Zhao; Huan-Jun, Zhao; Yong-Rui, Bao; Chen-Feng, Ji; Ning, Chen; Zheng, Xiang

    2015-01-01

    Background: Patrinia scabiosaefolia Fisch and Patrinia villosa (Thunb.) Juss., two species herbs with the same Chinese name “BaiJiangCao”, are important ancient herbal medicines widely used for more than 2000 years. The clinical application of two species herb is confused due to the difficult identification. Objective: The objective was to authenticate the species of BaiJiangCao and analyze the accumulation of bioactive ingredients based on characteristic inorganic elements analysis. Materials and Methods: Content of 32 inorganic elements in BaiJiangCao from different habitats were determined by inductively coupled plasma-mass spectrometry (ICP-MS), and the characteristic inorganic elements were picked to distinguish the species of the herb by principal component analysis and cluster analysis. Contents of two bioactive ingredients, luteoloside, and oleanolic acid, in the samples, were also analyzed by high-performance liquid chromatography method. Relationship between accumulation of bioactive ingredients and content of macroelements in BaiJiangCao was established by statistics. Results: A 4 macroelements (Na, Mg, K, Fe) in 32 determined inorganic elements were picked for characteristic inorganic elements. Content of Na, Mg, K and Fe showed positive correlations with that of luteoloside, content of Na, Mg showed positive correlations with that of oleanolic acid, but content of K and Fe showed negative correlations with that of oleanolic acid. Conclusion: It is for the first time to utilize the characteristic inorganic elements as an index to classify the herb species by the method of ICP-MS and multivariate analysis. And it is also the first report to investigate the influence of inorganic elements in herb on the accumulation of bioactive components which could affect the pharmacological efficacy of the herb medicine. And this method could also be utilized in research of corresponding aspects. PMID:26600721

  5. Accumulation of germanium and rare earth elements in functional groups of selected energy crops cultivated on two different soils

    NASA Astrophysics Data System (ADS)

    Wiche, Oliver; Székely, Balázs

    2016-04-01

    A field experiment was conducted to investigate the uptake of Ge and selected REEs in functional groups of selected crop species. Five species belonging to the functional group of grasses (Hordeum vulgare, Zea mays, Avena sativa, Panicum miliaceum and Phalaris arundinacea) and four species from the group of herbs (Lupinus albus, Lupinus angustifolius, Fagopyrum esculentum and Brassica napus) were cultivated in parallel on two soils with slightly alkaline (soil A: pH = 7.8) and slightly acidic (soil B: pH = 6.8) conditions. After harvest, concentrations of Ge, La, Nd, Gd, Er, P, Fe, Mn and Si in shoot tissues were determined with ICP-MS. Concentrations of Ge were significantly higher in grasses than in herbs. Conversely, concentrations of La and Nd were significantly higher in herbs, than in grasses. Highest concentrations were measured in Brassica napus (REEs) and Zea mays (Ge). Concentrations of Ge significantly correlated with that of Si in the shoots showing low concentrations in herbs and high concentrations in grasses, indicating a common mechanism during the uptake in grasses. Concentrations of REEs correlated significantly with that of Fe, indicating increasing concentrations of REEs with increasing concentrations of Fe. Cultivation of species on the slightly acidic soil significantly increased the uptake Ge in Lupinus albus and Phalaris arundinacea and the uptake of La and Nd in all species except of Phalaris arundinacea. This study demonstrated that commonly used field crops could be regarded as suitable candidates for a phytomining of Ge and REEs, since these species develop high yields of shoots, high concentrations of elements and are widely used in agricultural practice. Under soil conditions where bioavailability of Ge and REEs is expected to be low (soil A) accumulation can be estimated at 1.8 g/ha Ge in Z. mays and 3.7 g/ha REEs (1.5 g/ha La, 1.4 g/ha Nd, 0.6 g/ha Gd, 0.3 g/ha Er), respectively, in B. napus, assuming a constant high efficiency of

  6. Influence of ph in the Uptake and Accumulation of Mineral Elements on Vine Leaf (Vitis vinifera L.) from Castilla-La Mancha (SPAIN.)

    NASA Astrophysics Data System (ADS)

    Bravo, Sandra; Amorós, José Angel; Pérez-de-los-Reyes, Caridad; García-Navarro, Francisco J.; Higueras, Pablo; Sanchez-Ormeño, Mónica

    2015-04-01

    Each soil-plant system has specific parameters on the uptake of different minerals in the soil, depending on several factors. One of these factors, perhaps the most important, is the pH. 101 Vineyard plots have been selected in Castilla-La Mancha (Spain) and have been analysed (pH among other parameters) by the methods described by FAO. Leaf samples have also been taken in each plot. We analysed the content of 25 mineral elements in both soil and leaf through FRX technique. In addition, we calculated the BAC (bioaccumulation coefficient, calculated as the ratio between the concentration of element in the plant and soil) to stablish if the soil pH influences the accumulation of mineral elements for the plant. As a result we have observed a different behavior of groups of elements for acids or alkaline soils. Thus, the alkaline elements (Na, K, Rb) have a higher BAC value in alkaline soils except cesium (Cs) that has a similar value; while the alkaline-earth elements (Ca, Mg, Sr) present lower BAC in alkaline soils except for barium (Ba) that shows similar value in both cases. Rare Earths (Y, La, Ce, Th and Nd) have very similar values in bioaccumulation for acidic and alkaline soils, while metals (Fe, Al, V, Cr, Co, Cu, Rb and Pb) show a higher bioaccumulation in alkaline soils. Instead Mn, Zn and Ga are preferently bioaccumulated in acid soils. The values obtained for the sulfur (S) are superior in acid soils. We conclude that certain mineral elements accumulate in the leaves of vines depending on the soil pH. The pH will influence the ionic form in which the element is present in the soil and plants preferentially uptake mineral elements in certain ionic forms.

  7. Reduction of organic and inorganic selenium compounds by the edible medicinal basidiomycete Lentinula edodes and the accumulation of elemental selenium nanoparticles in its mycelium.

    PubMed

    Vetchinkina, Elena; Loshchinina, Ekaterina; Kursky, Viktor; Nikitina, Valentina

    2013-12-01

    We report for the first time that the medicinal basidiomycete Lentinula edodes can reduce selenium from inorganic sodium selenite (Se(IV)) and the organoselenium compound 1,5-diphenyl-3-selenopentanedione-1,5 (DAPS-25) to the elemental state, forming spherical nanoparticles. Submerged cultivation of the fungus with sodium selenite or with DAPS-25 produced an intense red coloration of L. edodes mycelial hyphae, indicating accumulation of elemental selenium (Se(0)) in a red modification. Several methods, including transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and X-ray fluorescence, were used to show that red Se(0) accumulated intracellularly in the fungal hyphae as electron-dense nanoparticles with a diameter of 180.51±16.82 nm. Under designated cultivation conditions, shiitake did not reduce selenium from sodium selenate (Se(VI)). PMID:24385361

  8. Seasonal Variation in the Accumulation of Trace Elements and Contaminants in Five Shrimp Species from Iskenderun Bay and Their Consumibility as Human Food.

    PubMed

    Kaymacı, Sevtap; Altun, Beyza Ersoy

    2016-08-01

    Seasonal accumulation of trace elements and contaminants in the muscle tissue of five shrimp species; Speckled Shrimp, Deepwater Rose Shrimp, Red Shrimp, Grooved Shrimp and Green Tiger Shrimp, from Iskenderun Bay of Eastern Mediterranean Sea were investigated. It was observed the period of year for the accumulation of such elements is important. Results indicate that peaks are generally reached in autumn and in spring. The levels of Zn, Fe, Cu and Ni were the highest in autumn whereas the maximum Sn and Cr concentrations were obtained in spring. The levels of Cu and Zn were found to be within the permissible limits for human consumption. Contaminants were accumulated at the highest levels in autumn. Attention has to be drawn that Cd values were above permissible limits for deepwater pink shrimp caught in autumn and winter, and for green tiger shrimp caught in autumn. Besides, the accumulation of high level of Pb in the tissue of all species except grooved shrimp whose value was low in spring should also be considered as a warning signal. PMID:27306878

  9. Environmental monitoring of the area surrounding oil wells in Val d'Agri (Italy): element accumulation in bovine and ovine organs.

    PubMed

    Miedico, Oto; Iammarino, Marco; Paglia, Giuseppe; Tarallo, Marina; Mangiacotti, Michele; Chiaravalle, A Eugenio

    2016-06-01

    In this work, environmental heavy metal contamination in the Val d'Agri area of Southern Italy was monitored, measuring the accumulation of 18 heavy metals (U, Hg, Pb, Cd, As, Sr, Sn, V, Ni, Cr, Mo, Co, Cu, Zn, Ca, Mn, Fe, and Al) in the organs of animals raised in the surrounding area (kidney, lung, and liver of bovine and ovine species). Val d'Agri features various oil processing centers which are potentially a significant source of environmental pollution, making it essential to perform studies that will outline the state of the art on which any recovery plans and interventions may be developed. The analysis was carried out using official and accredited analytical methods based on inductively coupled plasma mass spectrometry, and the measurements were statistically processed in order to give a contribution to risk assessment. Even though five samples showed Pb and Cd concentrations above the limits defined in the European Commission Regulation (EC) No 1881/2006, the mean concentrations of most elements suggest that contamination in this area is low. Consequently, these results also suggest that there is no particular risk for human exposure to toxic trace elements. Nevertheless, the findings of this work confirm that element accumulation in ovine species is correlated with geographical livestock area. Therefore, ovine-specific organs might be used as bioindicators for monitoring contamination by specific toxic elements in exposed areas. PMID:27165602

  10. [Increased accumulation of some trace elements in peripheral blood and bile of patients infested with Opisthorchis felineus (Rivolta, 1884) and Metorchis bilis (Braun, 1890)].

    PubMed

    Il'inskikh, E N; Il'inskikh, I N; Il'inskikh, N N

    2009-01-01

    The invasion with Opisthorchis felineus (Rivolta, 1884) is known to be common in the Ob River region, West Siberia. These trematodes parasitize biliary tract of devinitive host (man or some species of animals). Other opisthorchiid species occurring in West Siberia, Metorchis bilis (Braun, 1890), has also been recorded recently as human parasite. Life cycles of both these trematodes include fish-eating mammal hosts. Eggs of O. felineus and M. bilis are very similar morphologically and can hardly be indentified. Chronic invasion with the helminthes is found to be a cause of disbolism of trace elements or high accumulation of some essential and toxic elements in the organism of definitive host. The aim of the present study was to determine concentrations of some essential and toxic elements in samples of peripheral blood and bile obtained from patients infested with Opisthorchis and/or Metorchis using instrumental neuron-activation technique. At first, all patients with microscopically confirmed opisthorchiasis (by microscopic examination of faeces and bile for the helminth eggs) were examined with serological method (ELISA) for specific anti-Opisthorchis and anti-Metorchis antibodies. Among 139 examined patients, 56.1% had specific antibodies against both Opisthorchis and Metorchis, 41.7% showed anti-Opisthorchis antibodies only, and 2.1% turn out to be seropositive for anti-Metorchis antibodies only. Of 31 elements detected in the samples of peripheral blood and bile, the concentration of nine essential and toxic elements (mercury, chromium, cesium, rubidium, lanthanum, bromine, selenium, zinc, and cobalt) in the patients with the mixt-infection of Opisthorchis and Metorchis (78 individuals) and with the Opisthorchis mono-infection (58 individuals) were significantly higher than those in healthy uninfested individuals. Among these elements, mercury and chromium showed the highest concentrations in infested patients. We suggest that the significant increase in

  11. Modelling and mapping trace element accumulation in Sphagnum peatlands at the European scale using a geomatic model of pollutant emissions dispersion.

    PubMed

    Diaz-de-Quijano, Maria; Joly, Daniel; Gilbert, Daniel; Toussaint, Marie-Laure; Franchi, Marielle; Fallot, Jean-Michel; Bernard, Nadine

    2016-07-01

    Trace elements (TEs) transported by atmospheric fluxes can negatively impact isolated ecosystems. Modelling based on moss-borne TE accumulation makes tracking TE deposition in remote areas without monitoring stations possible. Using a single moss species from ombrotrophic hummock peatlands reinforces estimate quality. This study used a validated geomatic model of particulate matter dispersion to identify the origin of Cd, Zn, Pb and Cu accumulated in Sphagnum capillifolium and the distance transported from their emission sources. The residential and industrial sectors of particulate matter emissions showed the highest correlations with the TEs accumulated in S. capillifolium (0.28(Zn)-0.56(Cu)) and (0.27(Zn)-0.47(Cu), respectively). Distances of dispersion varied depending on the sector of emissions and the considered TE. The greatest transportation distances for mean emissions values were found in the industrial (10.6 km when correlating with all TEs) and roads sectors (13 km when correlating with Pb). The residential sector showed the shortest distances (3.6 km when correlating with Cu, Cd, and Zn). The model presented here is a new tool for evaluating the efficacy of air pollution abatement policies in non-monitored areas and provides high-resolution (200 × 200 m) maps of TE accumulation that make it possible to survey the potential impacts of TEs on isolated ecosystems. PMID:27061470

  12. Increased Variation in Adh Enzyme Activity in Drosophila Mutation-Accumulation Experiment Is Not Due to Transposable Elements at the Adh Structural Gene

    PubMed Central

    Aquadro, C. F.; Tachida, H.; Langley, C. H.; Harada, K.; Mukai, T.

    1990-01-01

    We present here a molecular analysis of the region surrounding the structural gene encoding alcohol dehydrogenase (Adh) in 47 lines of Drosophila melanogaster that have each accumulated mutations for 300 generations. While these lines show a significant increase in variation of alcohol dehydrogenase enzyme activity compared to control lines, we found no restriction map variation in a 13-kb region including the complete Adh structural gene and roughly 5 kb of both 5' and 3' sequences. Thus, the rapid accumulation of ADH activity variation after 28,200 allele generations does not appear to have been due to the mobilization of transposable elements into or out of the Adh structural gene region. PMID:1963870

  13. Lead, platinum, and other heavy elements in the primary cosmic radiation: HEAO-3 results ssc wg032961 cb553097

    NASA Technical Reports Server (NTRS)

    Waddington, C. J.; Binns, W. R.; Brewster, N. R.; Fixsen, D. J.; Garrard, T. L.; Israel, M. H.; Klarmann, J.; Newport, B. J.; Stone, E. C.

    1985-01-01

    An observation of the abundances of cosmic-ray lead and platinum-group nuclei using data from the HEAO-3 Heavy Nuclei Experiment (HNE) which consisted of ion chambers mounted on both sides of a plastic Cerenkov counter is reported. Further analysis with more stringent selections, inclusion of additional data, and a calibration at the LBL Bevalac, have allowed obtaining the abundance ratio of lead and the platinum group of elements for particles that had a cutoff rigidity R sub c 5 GV.

  14. Factors affecting accumulation of thallium and other trace elements in two wild Brassicaceae spontaneously growing on soils contaminated by tailings dam waste.

    PubMed

    Madejón, P; Murillo, J M; Marañón, T; Lepp, N W

    2007-02-01

    Thallium is a scarce, highly toxic element. There are several investigations that report Tl accumulation in plants of the family Brassicaceae. These plants could pose a risk in areas where Tl is present at higher concentrations than normal soils. The present study reports analyses of two wild Brassicaceae, Hirschfeldia incana and Diplotaxis catholica, growing spontaneously at five sampling sites moderately polluted with Tl and other trace elements in the Green Corridor of the Guadiamar river, Seville, S. Spain. In general, trace element content was unremarkable in all part plants, despite the concentrations present in soil. Thallium was the only element whose concentration in both plant species was above normal for plants (maximum values of 5.00 mgkg(-1) in H. incana flowers). There were significant positive correlations between total Tl in soil and Tl in both plant species. Transfer Coefficients (TC) for all elements were, in general, <1 for both species, except for Tl in flowers and fruits at some sites. The highest Enrichment Factor (EF) was found for Tl in H. incana fruits (EF = 607) and D. catholica flowers (EF = 321). H. incana was studied in a previous growing season (2004) in the same area, although the rainfall was 3 times more than in the year of the present study (2005), giving a maximum Tl content of 46.5 mgkg(-1) in H. incana flowers. The data presented here show that Tl content of plants growing in semi-arid conditions can be significantly influenced by precipitation. In dry years, plant Tl accumulation may be significantly reduced. PMID:17123576

  15. ACCUMULATION AND TISSUE DISPOSITION OF PARTICLE ASSOCIATED ELEMENTS IN THE RAT AFTER REPEATED INTRATRACHAEL ADMINISTRATION OF SOURCE PARTICLES

    EPA Science Inventory

    The goal of this study was to determine the fate of source particle tracer elements following repeated intratracheal instillation (IT) to rats. PM samples comprised Mt. St. Helens ash (MSH) with no water-soluble metals, and oil flyash emission PM (EPM) with water-leachable solubl...

  16. Tree bark suber-included particles: A long-term accumulation site for elements of atmospheric origin

    NASA Astrophysics Data System (ADS)

    Catinon, Mickaël; Ayrault, Sophie; Spadini, Lorenzo; Boudouma, Omar; Asta, Juliette; Tissut, Michel; Ravanel, Patrick

    2011-02-01

    The deposition of atmospheric elements on and into the bark of 4-year-old Fraxinus excelsior L. was studied. The elemental composition of the suber tissue was established through ICP-MS analysis and the presence of solid mineral particles included in this suber was established and described through SEM-EDX. Fractionation of the suber elements mixture was obtained after ashing at 550 °C through successive water (C fraction) and HNO 3 2 M (D fraction) extraction, leading to an insoluble residue mainly composed of the solid mineral particles (E fraction). The triplicated % weight of C, D and E were respectively 34.4 ± 2.7, 64.8 ± 2.7 and 0.8 ± 0.1% of the suber ashes weight. The main component of C was K, of D was Ca. Noticeable amounts of Mg were also observed in D. The E fraction, composed of insoluble particles, was mostly constituted of geogenic products, with elements such as Si, Al, K, Mg, representing primary minerals. E also contained Ca 3(PO 4) 2 and concentrated the main part of Pb and Fe. Moreover, The SEM-EDX analysis evidenced that this fraction also concentrated several types of fly ashes of industrial origin. The study of the distribution between C, D and E was analysed through ICP-MS with respect to their origin. The origin of the elements found in such bark was either geogenic (clay, micas, quartz…), anthropogenic or biogenic (for instance large amounts of solid Ca organic salts having a storage role). As opposed to the E fraction, the C fraction, mainly composed of highly soluble K+ is characteristic of a biological pool of plant origin. In fraction D, the very high amount of Ca++ corresponds to two different origins: biological or acid soluble minerals such as calcite. Furthermore, the D fraction contains the most part of pollutants of anthropic origin such as Zn, Cu, Ni, Co, Cd. As a whole, the fractionation procedure of the suber samples allows to separate elements as a function of their origin but also gives valuable information on

  17. Analysis of element accumulation in cell wall attached and intracellular particles of snow algae by EELS and ESI.

    PubMed

    Lütz-Meindl, Ursula; Lütz, Cornelius

    2006-01-01

    Snow algae frequently occur in alpine and polar permanent snow ecosystems and have developed adaptations to their harsh environment, where extreme temperature regimes high irradiation and low nutrient levels prevail. They live in a unique microhabitat, namely the liquid water between snow crystals. The predominant form appears as 'red snow' and in polar environment also 'green snow' frequently occurs. Light microscopy showed that most cells are densely covered by non-biotic particles of so far unknown composition. As snow normally contains very low amounts of nutrients, introduced mainly airborne like dust and precipitation, the inorganic particles at the surface of the snow algae may be important for their survival. By using electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI), we investigated element distribution in ultrathin sections of snow algae from different polar (Svalbard, 5 m a.s.l., 79 degrees N and maritime Antarctic, King George Island, 10 m a.s.l., 62 degrees S) and alpine habitats (2400-3100 m a.s.l. Tyrol) for the present study. It turned out that the main elements of the cell wall attached particles are Si, Al, Fe and O independently from the origin of the snow algae. Interestingly, the same elements were also found in vacuolar compartments inside the cells. These vacuoles contain electron dense granules or crystals and are frequently found to be connected to the cortical cytoplasm. This finding suggests an uptake mechanism of the respective elements by pinocytosis. Co-transport of toxic aluminium together with silicon may be unavoidable as the inorganic nutrient uptake of the snow algae is limited to the thin water layer between the ice crystals. However, formation of insoluble aluminium silicates may serve as detoxification mechanism. PMID:16376553

  18. Partitioning of trace elements and metals between quasi-ultrafine, accumulation and coarse aerosols in indoor and outdoor air in schools

    NASA Astrophysics Data System (ADS)

    Viana, M.; Rivas, I.; Querol, X.; Alastuey, A.; Álvarez-Pedrerol, M.; Bouso, L.; Sioutas, C.; Sunyer, J.

    2015-04-01

    Particle size distribution patterns of trace elements and metals across three size fractions (<0.25 μm, quasi-ultrafine particles, q-UF; 0.25-2.5 μm, accumulation particles; 2.5-10 μm, coarse particles) were analysed in indoor and outdoor air at 39 primary schools across Barcelona (Spain). Special attention was paid to emission sources in each particle size range. Results evidenced the presence in q-UF particles of high proportions of elements typically found in coarse PM (Ca, Al, Fe, Mn or Na), as well as several potentially health-hazardous metals (Mn, Cu, Sn, V, Pb). Modal shifts (e.g., from accumulation to coarse or q-UF particles) were detected when particles infiltrated indoors, mainly for secondary inorganic aerosols. Our results indicate that the location of schools in heavily trafficked areas increases the abundance of q-UF particles, which infiltrate indoors quite effectively, and thus may impact children exposure to these health-hazardous particles.

  19. Trace element and nutrient accumulation in sunflower plants two years after the Aznalcóllar mine spill.

    PubMed

    Madejón, P; Murillo, J M; Marañón, T; Cabrera, F; Soriano, M A

    2003-05-20

    The failure of a tailing pond dam at the Aznalcóllar pyrite mine (SW Spain) in April 1998 released a toxic spill affecting approximately 4300 ha along the Agrio and Guadiamar valleys. Two years later, we have studied yield and concentration of mineral nutrients and trace elements in sunflower plants grown in the spill-affected soil, and in an adjacent unaffected soil as comparison. The study has been carried out in plants at seedling (V4) and mature (R8) stages. Shoot and root biomass of sunflower seedlings was significantly smaller in the affected soil than in the unaffected soil, but there was no significant difference at the mature stage. Oil production was greater in the spill-affected plants. We have not detected any 'fertilising' effect caused by the acid waters of the spill on the main nutrient (N, P and Ca) acquisition, as documented in 1998 for sunflower plants flooded by the spill. Sunflower plants growing in the spill-affected soil reached adequate levels of nutrients. None of the trace elements measured-As, Cd, Cu, Pb and Tl-reached levels either phytotoxic or toxic for humans or animals in seeds and the above-ground part of the spill-affected plants. We evaluate the potential use of sunflower plants for phytoremediation. The potential for phytoextraction is very low; however, it may be used for soil conservation. The production of oil (usable for industrial purposes) may add some value to this crop. PMID:12711438

  20. Accumulation of trace elements, pesticides, and polychlorinated biphenyls in sediments and the clam Corbicula manilensis of the Apalachicola River, Florida

    USGS Publications Warehouse

    Elder, J.F.; Mattraw, H.C., Jr.

    1984-01-01

    A survey of trace element and synthetic organic compound concentrations in botton materials was conducted on the Apalachichola River in northwest Florida in 1979-80 as part of the Apalachicola River Quality Assessment. Substances analyzed included trace elements (predominantly heavy metals), organochlorine insecticides, organophosphorus insecticides, chlorinated phenoxy-acid herbicides, and polychlorinated biphenyls (PCBs). Three kinds of materials were surveyed: fine-grained sediments, whole-body tissue of the Asiatic clam Corbicula manilensis, and bottom-load organic detritus. No hazardous levels of any of the substances were found. Concentrations in the fine-grained sediments and clams were generally at least ten times lower than maximum limits considered safe for biota of aquatic systems. A comparison of trace-substance data from the Apalachicola River with data from Lake Seminole (upstream) and Apalachicola Bay (downstream) showed lower concentrations in riverine clams. Sediment concentrations in all parts of the system were comparable. Most trace substances in the Apalachicola River enter the river from the upstream part of the basin (the Chattahoochee and Flint Rivers in Georgia and Alabama) and from nonpoint sources throughout the basin. There are no major point discharges along the Apalachicola. Trend analysis was limited by the scope of the study, but did not reveal any spatial or temporal trends in concentrations of any of the substances analyzed. Concentrations of organic compounds and most metals in Corbicula manilensis did not correlate with those in sediments.

  1. Single-spore elemental analyses indicate that dipicolinic acid-deficient Bacillus subtilis spores fail to accumulate calcium.

    PubMed

    Hintze, Paul E; Nicholson, Wayne L

    2010-06-01

    Dipicolinic acid (pyridine-2,6-carboxylic acid; DPA) is a major component of bacterial spores and has been shown to be an important determinant of spore resistance. In the core of dormant Bacillus subtilis spores, DPA is associated with divalent calcium in a 1:1 chelate (Ca-DPA). Spores excrete Ca-DPA during germination, but it is unknown whether Ca and DPA are imported separately or together into the developing spore. Elemental analysis by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) of wild-type spores and mutant spores lacking the ability to synthesize DPA showed that DPA-less spores also lacked calcium, suggesting that the two compounds may be co-imported. PMID:20396869

  2. Accumulate repeat accumulate codes

    NASA Technical Reports Server (NTRS)

    Abbasfar, Aliazam; Divsalar, Dariush; Yao, Kung

    2004-01-01

    In this paper we propose an innovative channel coding scheme called 'Accumulate Repeat Accumulate codes' (ARA). This class of codes can be viewed as serial turbo-like codes, or as a subclass of Low Density Parity Check (LDPC) codes, thus belief propagation can be used for iterative decoding of ARA codes on a graph. The structure of encoder for this class can be viewed as precoded Repeat Accumulate (RA) code or as precoded Irregular Repeat Accumulate (IRA) code, where simply an accumulator is chosen as a precoder. Thus ARA codes have simple, and very fast encoder structure when they representing LDPC codes. Based on density evolution for LDPC codes through some examples for ARA codes, we show that for maximum variable node degree 5 a minimum bit SNR as low as 0.08 dB from channel capacity for rate 1/2 can be achieved as the block size goes to infinity. Thus based on fixed low maximum variable node degree, its threshold outperforms not only the RA and IRA codes but also the best known LDPC codes with the dame maximum node degree. Furthermore by puncturing the accumulators any desired high rate codes close to code rate 1 can be obtained with thresholds that stay close to the channel capacity thresholds uniformly. Iterative decoding simulation results are provided. The ARA codes also have projected graph or protograph representation that allows for high speed decoder implementation.

  3. Single-Kernel Ionomic Profiles Are Highly Heritable Indicators of Genetic and Environmental Influences on Elemental Accumulation in Maize Grain (Zea mays)

    PubMed Central

    Baxter, Ivan R.; Ziegler, Gregory; Lahner, Brett; Mickelbart, Michael V.; Foley, Rachel; Danku, John; Armstrong, Paul; Salt, David E.; Hoekenga, Owen A.

    2014-01-01

    The ionome, or elemental profile, of a maize kernel can be viewed in at least two distinct ways. First, the collection of elements within the kernel are food and feed for people and animals. Second, the ionome of the kernel represents a developmental end point that can summarize the life history of a plant, combining genetic programs and environmental interactions. We assert that single-kernel-based phenotyping of the ionome is an effective method of analysis, as it represents a reasonable compromise between precision, efficiency, and power. Here, we evaluate potential pitfalls of this sampling strategy using several field-grown maize sample sets. We demonstrate that there is enough genetically determined diversity in accumulation of many of the elements assayed to overcome potential artifacts. Further, we demonstrate that environmental signals are detectable through their influence on the kernel ionome. We conclude that using single kernels as the sampling unit is a valid approach for understanding genetic and environmental effects on the maize kernel ionome. PMID:24489944

  4. Trace element accumulation in short-tailed albatrosses (Diomedea albatrus) and black-footed albatrosses (Diomedea nigripes) from Torishima Island, Japan

    NASA Astrophysics Data System (ADS)

    Shinsuke, T.; Tokutaka, I.; Takashi, K.; Miyako, T.; Fumio, S.; Nariko, O.

    2003-05-01

    Concentrations of 19 trace elements (V, Cr, Mn, Co, Cu, Zn, Ga, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl, and Pb) were determined in liver, kidney, muscle, feather and stomach content of short-tailed albatross and feather of black-footed albatross from Torishima Island, Japan. For most of the elements, concentrations in liver and kidney were higher than those in muscle and feather, whereas concentrations of Ga, Sr and Ba were highest in feather of short-taled albatross. Metal concentrations in tissues of short-tailed albatross were within the range of those reported for albatrosses from other locations. Concentrations of Cr, Mn, Hg and Pb were relatively low in the tissues of short-tailed albatross, indicating less contamination by those metals in this species of Torishima Island. No significant differences were observed in metal concentrations in feather between short-tailed albatross and black-footed albatross. To our knowledge, this is the first report on the trace element accumulation in tissues of short-tailed albatross.

  5. Single-kernel ionomic profiles are highly heritable indicators of genetic and environmental influences on elemental accumulation in maize grain (Zea mays).

    PubMed

    Baxter, Ivan R; Ziegler, Gregory; Lahner, Brett; Mickelbart, Michael V; Foley, Rachel; Danku, John; Armstrong, Paul; Salt, David E; Hoekenga, Owen A

    2014-01-01

    The ionome, or elemental profile, of a maize kernel can be viewed in at least two distinct ways. First, the collection of elements within the kernel are food and feed for people and animals. Second, the ionome of the kernel represents a developmental end point that can summarize the life history of a plant, combining genetic programs and environmental interactions. We assert that single-kernel-based phenotyping of the ionome is an effective method of analysis, as it represents a reasonable compromise between precision, efficiency, and power. Here, we evaluate potential pitfalls of this sampling strategy using several field-grown maize sample sets. We demonstrate that there is enough genetically determined diversity in accumulation of many of the elements assayed to overcome potential artifacts. Further, we demonstrate that environmental signals are detectable through their influence on the kernel ionome. We conclude that using single kernels as the sampling unit is a valid approach for understanding genetic and environmental effects on the maize kernel ionome. PMID:24489944

  6. Accumulation and fractionation of rare earth elements in atmospheric particulates around a mine tailing in Baotou, China

    NASA Astrophysics Data System (ADS)

    Wang, Lingqing; Liang, Tao

    2014-05-01

    Rare earth elements (REEs) have been increasingly emitted into the atmosphere with a worldwide increase in use of these metals. However, the research on REEs in atmospheric particulates is fairly limited. In this paper, atmospheric particulates including total suspended particulate (TSP) matter and particles with an equivalent aerodynamic diameter less than 10 μm (PM10) were collected around a rare earth mine tailing in Baotou, the largest rare earth industrial base in China, in August 2012 and March 2013, for the analyses of REE levels and distributions. The total concentrations of REEs for TSP were 172.91 and 297.49 ng/m3, and those for PM10 were 63.23 and 105.52 ng/m3, in August 2012 and March 2013, respectively. Enrichment factors for all 14 analyzed REEs in the TSP and PM10 indicated that the REE enrichment in atmosphere particulates was caused by anthropogenic sources and influenced by the strong wind in spring season. The spatial distribution of REEs in TSP showed a strong gradient in the prevailing wind direction. The chondrite-normalized patterns of REEs in TSP and PM10 were similar with the conspicuous fractionation between light REEs and heavy REEs.

  7. Cultivation of garden vegetables in Peoria Pool sediments from the Illinois River: a case study in trace element accumulation and dietary exposures.

    PubMed

    Ebbs, Stephen; Talbott, Jonathan; Sankaran, Renuka

    2006-08-01

    This case study was conducted to evaluate the use of reclaimed lake sediment as a growth media for vegetable production and to estimate whether accumulation of micronutrients and heavy metals in the vegetables would impact human nutrition or health, respectively. Five plant species, bean (Phaseolus vulgaris L.), broccoli (Brassica oleracea L.), carrot (Daucus carota L.), pepper (Capsicum annum L.), and tomato (Lycopersicon esculentum L.), were grown in pots containing either reclaimed sediment from the Illinois River or a reference soil. Edible and vegetative tissues from the plants were analyzed for 19 elements, including As, Cd, Cr, Cu, Hg, Mo, Ni, Pb, Se, and Zn. Tomato and pepper grown in sediment showed significantly greater biomass and yield as compared to plants from the reference soil. Elemental analysis of the tissues revealed that Zn and Mo were the only elements that were significantly greater in sediment-grown plants on a consistent basis. While significant, Zn concentrations were no more than 3-fold higher than those in plants from the reference soil. The same trend was observed for Mo, except for bean tissues, which showed a 10-fold greater concentration in sediment-grown plants. The projected dietary intake of Cu, Mo, and Zn from consumption of sediment-grown vegetable tissues was significantly higher than for soil-grown plants, although the contribution to the recommended dietary allowances (RDAs) for these elements was substantial only for Mo. Intake of sediment-grown beans would have provided 500% of the dietary Mo RDA. While this is below the lowest observable adverse effect level (LOAEL) value for this element, there is no evidence to indicate that there would be a nutritional or therapeutic benefit from the consumption of bean containing this level of Mo. The dietary exposures to Cd and Pb would have been below the pertinent limits for all age and gender groups with the exception of the cumulative dietary Cd exposure to the 1-3 year age group

  8. Migration of trace elements from basalt substrate to co-located vegetation (lichens and mosses) at the Wudalianchi volcanos, Northeast China

    NASA Astrophysics Data System (ADS)

    Bao, Yuan; Ju, Yiwen; Li, Boping; Sun, Yimin

    2016-03-01

    Vegetation (e.g., lichens and mosses) living on the basalt substrate have potential to accumulate trace elements in their tissues. Here, we analyze the trace elements in basalt (collected from major volcanic center to jet plate places, representing four different eruption phases) and adjacent lichens and mosses to assess their elemental source-receptor relation. The results indicate that As, Sr, Mo, Cd, and Ba are enriched in basalt, and depleted in lichens and mosses. However, Zn, Hg, and Pb are enriched in lichens and mosses and depleted in basalt. Moreover, with the increase of basalt age, Cr, Mn, Fe, Ni, and Cu are gradually enriched in lichen and moss, but gradually depleted in basalt. Compared with transition metals, large ion lithophiles, the platinum group, and rare earth elements, Cr, Co, Cu, Zn, and Os are more easily absorbed by No. 1 lichen. Specifically, S is highly assimilated in vegetation, with a highest value of 166, followed by I, C, Pb, Zn, and Hg. In addition, the hydrogen and oxygen isotopic compositions of water samples suggest that the surface water in the Wenbo area came from meteoric waters in summer with a high humidity, while the underground water in the Beiyaoquan area came from meteoric waters in winter with a low humidity.

  9. Sources and accumulation of organic carbon in the Pearl River Estuary surface sediment as indicated by elemental, stable carbon isotopic, and carbohydrate compositions

    NASA Astrophysics Data System (ADS)

    He, B.; Dai, M.; Huang, W.; Liu, Q.; Chen, H.; Xu, L.

    2010-10-01

    Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized using a variety of techniques, including elemental (C and N) ratio, bulk stable organic carbon isotopic composition (δ13C), and carbohydrate composition analyses. Total organic carbon (TOC) content was 1.21±0.45% in the upper reach, down to 1.00±0.22% in Lingdingyang Bay and to 0.80±0.10% on the inner shelf and 0.58±0.06% on the outer shelf. δ13C values ranged from -25.1‰ to -21.3‰ in Lingdingyang Bay and the South China Sea shelf, with a trend of enrichment seawards. The spatial trend in C/N ratios mirrored that of δ13C, with a substantial decrease in C/N ratio offshore. Total carbohydrate yields ranged from 22.1 to 26.7 mg (100 mg OC)-1, and typically followed TOC concentrations in the estuarine and shelf sediments. Total neutral sugars, as detected by the nine major monosaccharides (lyxose, rhamnose, ribose, arabinose, fucose, xylose, galactose, mannose, and glucose), were between 4.0 and 18.6 mg (100 mg OC)-1 in the same sediments, suggesting that significant amounts of carbohydrates were not neutral aldoses. Using a two end-member mixing model based on δ13C values and C/N ratios, we estimated that the terrestrial organic carbon contribution to the surface sediment TOC was ca. 78±11% for Lingdingyang Bay, 34±4% for the inner shelf, and 5.5±1% for the outer shelf. The molecular composition of the carbohydrate in the surface sediments also suggested that the inner estuary was rich in terrestrially derived carbohydrates but that their contribution decreased offshore. A relatively high abundance of deoxyhexoses in the estuary and shelf indicated a considerable bacterial source of these carbohydrates, implying that sediment organic matter had undergone extensive degradation and/or transformation during transport. Sediment budget based on calculated regional accumulation rates

  10. Accumulation of As, Cd and selected trace elements in tubers of Scirpus aritimus L. from Doñana marshes (South Spain)

    USGS Publications Warehouse

    Madejon, P.; Murillo, J.M.; Maranon, T.; Espinar, J.L.; Cabrera, F.

    2006-01-01

    The collapse of a pyrite-mining, tailing dam on 1998 contaminated an area of 4286 ha along the Agrio and Guadiamar river valleys in southern Spain. Over 2700 ha of the Doñana marshes, an important wintering area for wetland European birds, were contaminated. This study reports analyses of the tubers of Scirpus maritimus (an important food for greylag geese, Anser anser) collected in 2000 in the “Entremuros” (spill-affected area) and in nearby unaffected Doñana marshes (control areas). In the spill-affected area mean tuber tissue concentrations of Cd (0.25 mg kg−1) and Zn (61 mg kg−1) were greater than in those tubers from the control area (0.02 mg kg−1 for Cd, and 22 mg kg−1 for Zn); values of Cd and Zn in “Entremuros” (samples collected two years after the mine spill) were much smaller than those reported only a few months after the accident. Trace elements (As, Fe, Mn and Tl, and to a lesser extent Cd and Pb) showed a preferential accumulation in the outer skin of tubers. Surprisingly, concentrations of As and Fe were greater in tubers from some marsh sites not affected by the mine-spill than in tubers from the “Entremuros”. We suggest that relic river channels within the Doñana marshes may be contaminated by trace elements from historic mining activities. An exhaustive study of macrophytes and other plant species in this area is recommended to identify potential risks to wildlife.