Geostandards and Geoanalytical Research Bibliographic Review 2014          下载免费PDF全文

Ulrike Weis  Beate Schwager  Uwe Nohl  Laura M. Otter  Brigitte Stoll  Patricia Karlowski  Klaus Peter Jochum 《Geostandards and Geoanalytical Research》2015,39(4):497-500

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GGR Biennial Critical Review: Analytical Developments Since 2014          下载免费PDF全文

Kathryn L. Linge  L. Paul Bédard  Roxana Bugoi  Jacinta Enzweiler  Klaus Peter Jochum  Rüdiger Kilian  Jingao Liu  Johanna Marin‐Carbonne  Silke Merchel  Frans Munnik  Luiz F.G. Morales  Claire Rollion‐Bard  A. Kate Souders  Paul J. Sylvester  Ulrike Weis 《Geostandards and Geoanalytical Research》2017,41(4):493-562

This GGR biennial critical review covers developments and innovations in key analytical methods published since January 2014, relevant to the chemical, isotopic and crystallographic characterisation of geological and environmental materials. In nine selected analytical fields, publications considered to be of wide significance are summarised, background information is provided and their importance evaluated. In addition to instrumental technologies, this review also presents a summary of new developments in the preparation and characterisation of rock, microanalytical and isotopic reference materials, including a précis of recent changes and revisions to ISO guidelines for reference material characterisation and reporting. Selected reports are provided of isotope ratio determinations by both solution nebulisation MC‐ICP‐MS and laser ablation‐ICP‐MS, as well as of radioactive isotope geochronology by LA‐ICP‐MS. Most of the analytical techniques elaborated continue to provide new applications for geochemical analysis; however, it is noted that instrumental neutron activation analysis has become less popular in recent years, mostly due to the reduced availability of nuclear reactors to act as a neutron source. Many of the newer applications reported here provide analysis at increasingly finer resolution. Examples include atom probe tomography, a very sensitive method providing atomic scale information, nanoscale SIMS, for isotopic imaging of geological and biological samples, and micro‐XRF, which has a spatial resolution many orders of magnitude smaller than conventional XRF.  相似文献   

Release into the environment of metals by two vascular salt marsh plants   总被引：6，自引：0，他引：6  

Weis P  Windham L  Burke DJ  Weis JS 《Marine environmental research》2002,54(3-5):325-329

Metals in contaminated salt marshes are mainly locked in the anaerobic layer of sediments, where they are tightly bound as sulfides and organic complexes. Vascular plants survive in saturated soils in part by pumping O2 into their root zones, changing their microenvironment to an oxic one. This, along with chelating exudates, mobilizes metals, allowing uptake by the roots. We compared the common reed Phragmites australis and cordgrass Spartina alterniflora in lab and field studies for ways in which they handle trace metals. Both plants store most of their metal burden in their roots, but some is transported to aboveground tissues. Spartina leaves contain approximately 2-3 x more Cr, Pb, and Hg than Phragmites leaves, but equivalent Cu and Zn. Furthermore, Spartina leaves have salt glands, so leaf excretion of all metals is twice that of Phragmites. In-depth studies with Hg indicate that Hg excretion correlates with Na release but not with transpiration, which is 2.2 x higher in Phragmites; and that more Hg accumulates in early-appearing leaves than in upper (i.e. later) leaves in both species. Spartina thus makes more metals available to salt marsh ecosystems than Phragmites by direct excretion and via dead leaves which will enter the food web as detritus.  相似文献   

Effect of zinc on regeneration in the fiddler crab Uca pugilator and its interactions with methylmercury and cadmium     

Judith Shulman Weis 《Marine environmental research》1980,3(4):249-255

After multiple autotomy (one chela and six walking legs) fiddler crabs (Uca pugilator) were exposed to zinc chloride, cadmium chloride, methylmercuric chloride or combinations of these metals. Zinc at 1, 3 and 5 ppm had a retarding effect on limb regeneration, which was amplified in water of reduced salinity. Methylmercury at 0·5 ppm and cadmium at 1·0 ppm have previously been found to retard regeneration. When crabs were exposed to meHg and Zn the effects were additive, both in sea water (30% salinity) and in water of reduced salinity (7–8%). However, when crabs were exposed to combinations of Zn and Cd the effects were antagonistic and the rate of regeneration was almost that of controls. In water of 7–8% salinity the Cd effect was greatly intensified and growth was almost totally prevented. The presence of Zn counteracted this and allowed growth and ecdysis to occur.  相似文献   

Assessing vulnerability: an integrated approach for mapping adaptive capacity,sensitivity, and exposure     

Shawn W. Margles Weis  Vera N. Agostini  Lynnette M. Roth  Ben Gilmer  Steven R. Schill  John English Knowles  Ruth Blyther 《Climatic change》2016,136(3-4):615-629

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VRI photometry of late dwarf common proper motion stars     

Edward W. Weis 《Astrophysics and Space Science》1988,142(1-2):223-225

Summary From the photometric observations of a sample of late dwarf common proper motion pairs it may be inferred that about 30%–50% of such systems contain one or more additional stellar components. A small fraction of such systems have separations in excess of 5000 A.U.  相似文献   

A Common Reference Material for Cadmium Isotope Studies – NIST SRM 3108     

Wafa Abouchami  Stephen J. G. Galer  Tristan J. Horner  Mark Rehkämper  Frank Wombacher  Zichen Xue  Myriam Lambelet  Melanie Gault‐Ringold  Claudine H. Stirling  Maria Schönbächler  Alyssa E. Shiel  Dominique Weis  Philip F. Holdship 《Geostandards and Geoanalytical Research》2013,37(1):5-17

Research into natural mass‐dependent stable isotope fractionation of cadmium has rapidly expanded in the past few years. Methodologies are diverse with MC‐ICP‐MS favoured by all but one laboratory, which uses thermal ionisation mass spectrometry (TIMS). To quantify the isotope fractionation and correct for instrumental mass bias, double‐spike techniques, sample‐calibrator bracketing or element doping has been used. However, easy comparison between data sets has been hampered by the multitude of in‐house Cd solutions used as zero‐delta reference in different laboratories. The lack of a suitable isotopic reference material for Cd is detrimental for progress in the long term. We have conducted a comprehensive round‐robin assay of NIST SRM 3108 and the Cd isotope offsets to commonly used in‐house reference materials. Here, we advocate NIST SRM 3108 both as an isotope standard and the isotopic reference point for Cd and encourage its use as ‘zero‐delta’ in future studies. The purity of NIST SRM 3108 was evaluated regarding isobaric and polyatomic molecular interferences, and the levels of Zn, Pd and Sn found were not significant. The isotope ratio ¹¹⁴Cd/¹¹⁰Cd for NIST SRM 3108 lies within ～ 10 ppm Da^?1 of best estimates for the Bulk Silicate Earth and is validated for all measurement technologies currently in use.  相似文献   

Geostandards and Geoanalytical Research Bibliographic Review 2012     

Klaus Peter Jochum  Uwe Nohl  Nadja Rothbarth  Beate Schwager  Brigitte Stoll  Ulrike Weis 《Geostandards and Geoanalytical Research》2013,37(4):469-473

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Geochemical constraints on the origin of the late Jurassic proto-Caribbean oceanic crust in Hispaniola     

J. Escuder Viruete  A. Pérez-Estaún  D. Weis 《International Journal of Earth Sciences》2009,98(2):407-425

The nature of the oceanic crust produced through rifting and oceanic spreading between North and South America during the Late Jurassic is a key element for the Caribbean plate tectonic model reconstruction. Located in the Cordillera Central of Hispaniola, the Loma La Monja volcano-plutonic assemblage (LMA) is composed of gabbros, dolerites, basalts, and oceanic sediments, as well as metamorphic equivalents, which represent a dismembered fragment of this proto-Caribbean oceanic crust. Petrologic and geochemical data show that the LMA have a relatively broad diversity in composition, which represent the crystallization products of a typical low-pressure tholeiitic fractionation of mid-ocean ridge basalts (MORB)-type parental magmas, ranging from N- to E-MORB. Three geochemical groups have been distinguished in the volcanic sequence: LREE-flat to slightly LREE-enriched basalts of groups II and III occur interlayered in the lower stratigraphic levels; and LREE-depleted basalts of group I in the upper levels. Mantle melt modeling suggests that group III magmas are consistent by mixing within a mantle melt column of low-degree (<1%) melts of a deep garnet lherzolite source and high-degree (>15%) melts of a shallow spinel source, and groups II and I magmas are explained with moderate to high (14–18%) and very high (>20%) fractional melting degrees of a shallower spinel mantle source, respectively. Thus, upward in the volcanic sequence of the LMA, the magmas represent progressively more extensive melting of shallower sources, in a plume-influenced spreading ridge of the proto-Caribbean oceanic crust. Nb/Y versus Zr/Y systematics combined with recent plate tectonic model reconstructions reveal that Caribbean Colombian oceanic plateau fragments in Hispaniola formed through melting of heterogeneous mantle source regions related with distinct plumes during at least from Aptian–Albian (>96 Ma) to Late Campanian.  相似文献   

Is the invasion of the common reed,Phragmites australis,into tidal marshes of the eastern US an ecological disaster?     

Weis JS  Weis P 《Marine pollution bulletin》2003,46(7):816-820

Studies of effects of the invasive brackish marsh plant Phragmites australis (common reed) on estuarine biota are reviewed. With few exceptions, most field studies indicate that these P. australis-dominated marshes have diverse and abundant benthic biota, and are utilized by nekton, comparable to Spartina alterniflora marshes. However, larval mummichogs, Fundulus heteroclitus, appear to be reduced in P. australis marshes compared with S. alterniflora marshes. Small epifauna living on plant stems also appear to be denser on S. alterniflora than P. australis stems. Other studies indicate that the detritus produced by decaying P. australis litter provides food value comparable to that of S. alterniflora and that its production enters estuarine food webs. Therefore, the general assumption that these marshes are ecologically "useless" is untrue. This information should be considered by marsh managers when making decisions about restoration projects.  相似文献