Publications
203 results found
Paul M, van de Flierdt T, Rehkamper M, et al., 2015, Tracing the Agulhas leakage with lead isotopes, Geophysical Research Letters, Vol: 20, Pages: 8515-8521, ISSN: 1944-8007
The transport of warm and salty waters from the Indian Ocean to the South Atlantic by the Agulhas Current constitutes a key return route of the meridional overturning circulation. Despite, the importance of the Agulhas Leakage on interoceanic exchange, its role on biogeochemical cycles is poorly documented. Here, we present the first lead (Pb) concentration and isotope data for surface seawater collected during the GEOTRACES cruise D357 in the Agulhas current system. Lead in surface waters of the Cape Basin is described by three distinct endmembers: the South African coast, open South Atlantic seawater, and Indian Ocean seawater. The latter stands out in its Pb isotopic composition and can be tracked within two distinct Agulhas rings. High Pb concentrations in the Agulhas rings further corroborate an Indian Ocean provenance of waters, and suggests that the Agulhas Leakage not only represents a major conduit for heat, but also for trace metals.
Stumpf R, Poole GM, Rehkamper M, 2015, Platinum isotope anomalies in meteorites, Goldschmidt Conference, Prague, Czech Republic
Isotopic heterogeneities in bulk meteorites have been reported for various elements, including Mo and Ba, suggesting incomplete mixing of at least some nucleosynthetic components in the early solar system. Here, we present the first results obtained in a coupled search of nucleosynthetic and stable Pt isotope anomalies in chondrites, to better constrain the nature and origin of such isotopic heterogeneities. Platinum is a highly siderophile element with six stable isotopes of very different abundances: 190Pt (0.01%), 192Pt (0.78%), 194Pt (32.97%), 195Pt (33.83%), 196Pt (25.24%), and 198Pt (7.16%). Precise Pt isotope measurements are hindered by various isobaric interferences (190Os, 192Os, 196Hg, 198Hg) and potential peak tailing effects (191Ir, 193Ir). Since the low abundance 192Pt is the only Pt isotope that is almost exclusively formed by slow neutron capture (s-process) during nucleosynthesis, it is imperative that samples are carefully purified prior to isotopic analyses to ensure reliable determination of nucleosynthetic Pt isotope anomalies. The method for high-precision stable Pt isotope measurements utilizes a Pt double spike with enriched 198Pt and 196Pt [1].To separate Pt from the chondritic sample matrix, and in particular from Os and Ir, we modified and optimized chemical purification procedures described in earlier studies [2][3]. To date, both spiked and non-spiked Pt isotope measurements were carried out on the IRMM-010 Pt standard reference material and two ordinary chondrites from North West Africa (NWA).Our preliminary analyses document an essentially identical stable δ198/194Pt for the chondrites (NWA-1 δ198/194Pt = –0.04‰; NWA-2 δ198/194Pt = +0.02‰; n = 6, ±0.07‰ 2SE) relative to IRMM-010 Pt (δ198/194Pt = 0). The first analyses of nucleosynthetic Pt isotope anomalies returned patterns that are not in accord with modelling results of purely nucleosynthetic Pt isotope effects, potentially
Wilson DJ, van de Flierdt T, Bridgestock LJ, et al., 2015, Exploring Pb isotopes in deep-sea corals: measurement by TIMS and application to the deglacial Southern Ocean, 25th Annual VM Goldschmidt Conference
Murphy K, Rehkämper M, Kreissig K, et al., 2015, Improvements in Cd stable isotope analysis achieved through use of liquid–liquid extraction to remove organic residues from Cd separates obtained by extraction chromatography, Journal of Analytical Atomic Spectrometry, Vol: 31, Pages: 319-327, ISSN: 1364-5544
Organic compounds released from resins that are commonly employed for trace element separations are known to have a detrimental impact on the quality of isotopic analyses by MC-ICP-MS. A recent study highlighted that such effects can be particularly problematic for Cd stable isotope measurements (M. Gault-Ringold and C. H. Stirling, J. Anal. At. Spectrom., 2012, 27, 449–459). In this case, the final stage of sample purification commonly applies extraction chromatography with Eichrom TRU resin, which employs particles coated with octylphenyl-N,N-di-isobutyl carbamoylphosphine oxide (CMPO) dissolved in tri-n-butyl phosphate (TBP). During chromatography, it appears that some of these compounds are eluted alongside Cd and cannot be removed by evaporation due to their high boiling points. When aliquots of the zero-ε reference material were processed through the purification procedure, refluxed in concentrated HNO3 and analyzed at minimum dilution (in 1 ml 0.1 M HNO3), they yielded Cd isotopic compositions (ε114/110Cd = 4.6 ± 3.4, 2SD, n = 4) that differed significantly from the expected value, despite the use of a double spike technique to correct for instrumental mass fractionation. This result was accompanied by a 35% reduction in instrumental sensitivity for Cd. With increasing dilution of the organic resin residue, both of these effects are reduced and they are insignificant when the eluted Cd is dissolved in ≥3 ml 0.1 M HNO3. Our results, furthermore, indicate that the isotopic artefacts are most likely related to anomalous mass bias behavior. Previous studies have shown that perchloric acid can be effective at avoiding such effects (Gault-Ringold and Stirling, 2012; K. C. Crocket, M. Lambelet, T. van de Flierdt, M. Rehkämper and L. F. Robinson, Chem. Geol., 2014, 374–375, 128–140), presumably by oxidizing the resin-derived organics, but there are numerous disadvantages to its use. Here we show that liquid–liqui
Arnold T, Markovic T, Kirk GJD, et al., 2015, Iron and zinc isotope fractionation during uptake and translocation in rice (Oryza sativa) grown in oxic and anoxic soils, Comptes Rendus Geoscience, Vol: 347, Pages: 397-404, ISSN: 1631-0713
Stable isotope fractionation is emerging quickly as a powerful novel technique to study metal uptake and translocation in plants. Fundamental to this development is a thorough understanding of the processes that lead to isotope fractionation under differing environmental conditions. In this study, we investigated Zn and Fe isotope fractionation in rice grown to maturity in anaerobic and aerobic soils under greenhouse conditions. The overall Zn isotope fractionation between the soil and above ground plant material was negligible in aerobic soil but significant in anaerobic soil with isotopically lighter Zn in the rice plant. The observed range of fractionation is in line with previously determined fractionations of Zn in rice grown in hydroponic solutions and submerged soils and emphasizes the effect of taking up different chemical forms of Zn, most likely free and organically complexed Zn. The Zn in the grain was isotopically lighter than in the rest of the above ground plant in rice grown in aerobic and anaerobic soils alike. This suggests that in the course of the grain loading and during the translocation within the plant important biochemical and/or biophysical processes occur. The isotope fractionation observed in the grains would be consistent with an unidirectional controlled transport from shoot to grain with a fractionation factor of α ≈ 0.9994. Iron isotopes showed an isotopic lighter signature in shoot and grain compared to the bulk soil or the leachate in aerobic and anaerobic soils alike. The negative direction of isotopic fractionation is consistent with possible changes in the redox state of Fe occurring during the uptake and translocation processes. The isotope fractionation pattern between shoots and grain material are different for Zn and Fe which finally suggests that different mechanisms operate during translocation and grain-loading in rice for these two key micronutrients.
Laycock A, Coles B, Kreissig K, et al., 2015, High precision Ce-142/Ce-140 stable isotope measurements of purified materials with a focus on CeO2 nanoparticles, Journal of Analytical Atomic Spectrometry, Vol: 31, Pages: 297-302, ISSN: 1364-5544
Engineered CeO2 nanoparticles (NPs) are becoming increasingly prevalent in consumer products and this has raised concerns about the unknown behaviour and fate of such materials in the environment. Analytical limitations have hampered the detection of CeO2 NPs in natural systems at environmentally relevant levels. This study presents data on the inherent stable isotope composition of commercially available purified Ce materials with a particular focus on CeO2 NPs. The aim of this investigation is to determine whether CeO2 NPs posses a distinct isotopic signature that may be exploited for their detection in natural systems. To achieve this, suitable stable isotope measurement protocols were developed for the precise determination of the 142Ce/140Ce isotope ratio by multiple collector ICP-MS using Ba for external normalisation of the instrumental mass bias. The data presented show that precisions of ±0.01‰ (2se) and ±0.04‰ (2sd) can be routinely achieved with these techniques. The results also demonstrate that commercially available CeO2 NPs do not have a distinct Ce isotope composition that may be exploited for the purpose of stable isotope tracing.
Paul M, Bridgestock L, Rehkaemper M, et al., 2015, High-precision measurements of seawater Pb isotope compositions by double spike thermal ionization mass spectrometry, ANALYTICA CHIMICA ACTA, Vol: 863, Pages: 59-69, ISSN: 0003-2670
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- Citations: 24
Hezel DC, Poole GM, Hoyes J, et al., 2015, Fe and O isotope composition of meteorite fusion crusts: Possible natural analogues to chondrule formation?, METEORITICS & PLANETARY SCIENCE, Vol: 50, Pages: 229-242, ISSN: 1086-9379
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- Citations: 18
Georgiev SV, Horner TJ, Stein HJ, et al., 2015, Cadmium-isotopic evidence for increasing primary productivity during the Late Permian anoxic event, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 410, Pages: 84-96, ISSN: 0012-821X
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- Citations: 52
Larner F, Woodley LN, Shousha S, et al., 2015, Zinc isotopic compositions of breast cancer tissue, Metallomics: integrated biometal science, Vol: 7, Pages: 107-112, ISSN: 1756-5901
An early diagnostic biomarker for breast cancer is essential to improve outcome. High precision isotopic analysis, originating in Earth sciences, can detect very small shifts in metal pathways. For the first time, the natural intrinsic Zn isotopic compositions of various tissues in breast cancer patients and controls were determined. Breast cancer tumours were found to have a significantly lighter Zn isotopic composition than the blood, serum and healthy breast tissue in both groups. The Zn isotopic lightness in tumours suggests that sulphur rich metallothionein dominates the isotopic selectivity of a breast tissue cell, rather than Zn-specific proteins. This reveals a possible mechanism of Zn delivery to Zn-sequestering vesicles by metallothionein, and is supported by a similar signature observed in the copper isotopic compositions of one breast cancer patient. This change in intrinsic isotopic compositions due to cancer has the potential to provide a novel early biomarker for breast cancer.
Wilson DJ, van de Flierdt T, Bridgestock LJ, et al., 2014, Radiogenic isotopes as paleoceanographic tracers in deep-sea corals: advances in TIMS measurements of Pb isotopes and application to Southern Ocean corals, American Geophysical Union Fall Meeting 2014
Coggon RM, Rehkaemper M, Atteck C, et al., 2014, Controls on thallium uptake during hydrothermal alteration of the upper ocean crust, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 144, Pages: 25-42, ISSN: 0016-7037
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- Citations: 25
Kersten M, Xiao T, Kreissig K, et al., 2014, Tracing Anthropogenic Thallium in Soil Using Stable Isotope Compositions, ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 48, Pages: 9030-9036, ISSN: 0013-936X
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- Citations: 47
Bridgestock LJ, Williams H, Rehkaemper M, et al., 2014, Unlocking the zinc isotope systematics of iron meteorites, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 400, Pages: 153-164, ISSN: 0012-821X
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- Citations: 30
Murphy K, Rehkaemper M, van de Flierdt T, 2014, Comment on "The isotopic composition of cadmium in the water column of the South China Sea", GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 134, Pages: 335-338, ISSN: 0016-7037
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- Citations: 4
Laycock A, Stolpe B, Roemer I, et al., 2014, Synthesis and characterization of isotopically labeled silver nanoparticles for tracing studies, ENVIRONMENTAL SCIENCE-NANO, Vol: 1, Pages: 271-283, ISSN: 2051-8153
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- Citations: 25
Crocket KC, Lambelet M, de Flierdt TV, et al., 2014, Measurement of fossil deep-sea coral Nd isotopic compositions and concentrations by TIMS as NdO<SUP>+</SUP>, with evaluation of cleaning protocols, CHEMICAL GEOLOGY, Vol: 374, Pages: 128-140, ISSN: 0009-2541
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- Citations: 24
Hettmann K, Kreissig K, Rehkaemper M, et al., 2014, Thallium geochemistry in the metamorphic Lengenbach sulfide deposit, Switzerland: Thallium-isotope fractionation in a sulfide melt, AMERICAN MINERALOGIST, Vol: 99, Pages: 793-803, ISSN: 0003-004X
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- Citations: 26
Larner F, Gulson B, McCall M, et al., 2014, An inter-laboratory comparison of high precision stable isotope ratio measurements for nanoparticle tracing in biological samples, JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, Vol: 29, Pages: 471-477, ISSN: 0267-9477
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- Citations: 13
Hettmann K, Marks MAW, Kreissig K, et al., 2014, The geochemistry of Tl and its isotopes during magmatic and hydrothermal processes: The peralkaline Ilimaussaq complex, southwest Greenland, CHEMICAL GEOLOGY, Vol: 366, Pages: 1-13, ISSN: 0009-2541
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- Citations: 27
Xue Z, Rehkaemper M, Horner TJ, et al., 2013, Cadmium isotope variations in the Southern Ocean, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 382, Pages: 161-172, ISSN: 0012-821X
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- Citations: 62
Nielsen SG, Wasylenki LE, Rehkaemper M, et al., 2013, Towards an understanding of thallium isotope fractionation during adsorption to manganese oxides, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 117, Pages: 252-265, ISSN: 0016-7037
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- Citations: 85
Khan FR, Laycock A, Dybowska A, et al., 2013, Stable Isotope Tracer To Determine Uptake and Efflux Dynamics of ZnO Nano- and Bulk Particles and Dissolved Zn to an Estuarine Snail, ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 47, Pages: 8532-8539, ISSN: 0013-936X
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- Citations: 39
Abouchami W, Galer SJG, Horner TJ, et al., 2013, A Common Reference Material for Cadmium Isotope Studies - NIST SRM 3108, GEOSTANDARDS AND GEOANALYTICAL RESEARCH, Vol: 37, Pages: 5-17, ISSN: 1639-4488
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- Citations: 102
Theis KJ, Schoenbaechler M, Benedix GK, et al., 2013, Palladium-silver chronology of IAB iron meteorites, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 361, Pages: 402-411, ISSN: 0012-821X
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- Citations: 33
Lambelet M, Rehkaemper M, de Flierdt TV, et al., 2013, Isotopic analysis of Cd in the mixing zone of Siberian rivers with the Arctic Ocean-New constraints on marine Cd cycling and the isotope composition of riverine Cd, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 361, Pages: 64-73, ISSN: 0012-821X
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- Citations: 50
Goldberg T, Gordon G, Izon G, et al., 2013, Resolution of inter-laboratory discrepancies in Mo isotope data: an intercalibration, JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, Vol: 28, Pages: 724-735, ISSN: 0267-9477
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- Citations: 131
Larner F, Dogra Y, Dybowska A, et al., 2012, Tracing Bioavailability of ZnO Nanoparticles Using Stable Isotope Labeling, ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 46, Pages: 12137-12145, ISSN: 0013-936X
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- Citations: 60
Boyle EA, John S, Abouchami W, et al., 2012, GEOTRACES IC1 (BATS) contamination-prone trace element isotopes Cd, Fe, Pb, Zn, Cu, and Mo intercalibration, LIMNOLOGY AND OCEANOGRAPHY-METHODS, Vol: 10, Pages: 653-665, ISSN: 1541-5856
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- Citations: 89
Giscard MD, Hammond SJ, Bland PA, et al., 2012, TRACE ELEMENT COMPOSITION OF METAL AND SULPHIDES IN IRON METEORITES DETERMINED USING ICP-MS, 75th Annual Meeting of the Meteoritical-Society, Publisher: WILEY-BLACKWELL, Pages: A149-A149, ISSN: 1086-9379
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