Nano‐Powdered Calcium Carbonate Reference Materials: Significant Progress for Microanalysis?     

Klaus Peter Jochum  Dieter Garbe‐Schnberg  Marina Veter  Brigitte Stoll  Ulrike Weis  Michael Weber  Federico Lugli  Anna Jentzen  Ralf Schiebel  Jasper A. Wassenburg  Dorrit E. Jacob  Gerald H. Haug 《Geostandards and Geoanalytical Research》2019,43(4):595-609

Homogeneity, mass fractions of about forty trace elements and Sr isotope composition of Ca carbonate reference materials (RMs) between original and nano‐powdered pellets are compared. Our results using nanosecond and femtosecond LA‐(MC)‐ICP‐MS show that the nano‐pellets of the RMs MACS‐3NP, JCp‐1NP and JCt‐1NP are about a factor of 2–3 more homogeneous than the original samples MACS‐3, JCp‐1 and JCt‐1, and are therefore much more suitable for microanalytical purposes. With the exception of Si, the mass fractions of the synthetic RM MACS‐3 agree with its fine‐grained analogue MACS‐3NP. Very small, but significant, differences between original and nano‐pellets are observed in the RMs JCp‐1 and JCt‐1 for some trace elements with very low contents, indicating the need for re‐certification. Strontium mass fractions in the analysed RMs are high (1500–7000 mg kg^?1), and their isotope compositions determined by LA‐MC‐ICP‐MS in the original and the nano‐pellets agree within uncertainty limits.  相似文献   

Molting as a mechanism of depuration of metals in the fiddler crab, Uca pugnax     

Bergey LL  Weis JS 《Marine environmental research》2007,64(5):556-562

Metal distributions in the exoskeleton and soft tissues of the fiddler crab, Uca pugnax, were examined during intermolt and immediate postmolt to determine if distribution of the metals changed prior to molting and to determine if molting is a feasible mechanism to depurate metals. Fiddler crabs were collected from two locations in New Jersey, a highly contaminated site and a relatively clean environment. The crabs from the contaminated site had higher concentrations of metals in their soft tissues for Cu, significantly higher concentrations of Pb in their soft tissues and carapace, but did not have any significant differences in concentrations of Zn in comparison to their conspecifics from the relatively clean site during intermolt. Crabs from the contaminated site has significantly higher levels of Cu, Pb, and Zn in both their soft tissues and exuvia immediately after molting. Crabs from both sites shifted copper and zinc from the carapace into the soft tissues prior to molting. Lead distribution shifted from the soft tissues to the exoskeleton prior to molting in the population from the contaminated site but shifted from the exoskeleton into the soft tissues for the relatively clean site. Average percent of the total body burden eliminated during the molting process for the highly contaminated site varied with each metal, 12% Cu, 76% Pb, and 22% Zn. Average percent of the total body burden eliminated during molting process for the relatively clean site also varied with each metal and was significantly lower than the conspecifics from the contaminated site, 3% Cu, 56% Pb, and 8% Zn. Molting can reduce overall body burdens significantly and is a feasible mechanism to depurate lead.  相似文献   

Geostandards and Geoanalytical Research Bibliographic Review 2015   总被引：1，自引：0，他引：1       下载免费PDF全文

Ulrike Weis  Beate Schwager  Uwe Nohl  Patricia Karlowski  Laura M. Otter  Brigitte Stoll  Klaus Peter Jochum 《Geostandards and Geoanalytical Research》2016,40(4):599-601

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Reference Values Following ISO Guidelines for Frequently Requested Rock Reference Materials   总被引：2，自引：0，他引：2       下载免费PDF全文

Klaus Peter Jochum  Ulrike Weis  Beate Schwager  Brigitte Stoll  Stephen A. Wilson  Gerald H. Haug  Meinrat O. Andreae  Jacinta Enzweiler 《Geostandards and Geoanalytical Research》2016,40(3):333-350

We present new reference values for nineteen USGS, GSJ and GIT‐IWG rock reference materials that belong to the most accessed samples of the GeoReM database. The determination of the reference values and their uncertainties at the 95% confidence level follows as closely as possible ISO guidelines and the Certification Protocol of the International Association of Geoanalysts. We used analytical data obtained by the state‐of‐the‐art techniques published mainly in the last 20 years and available in GeoReM. The data are grouped into four categories of different levels of metrological confidence, starting with isotope dilution mass spectrometry as a primary method. Data quality was checked by careful investigation of analytical procedures and by the application of the Horwitz function. As a result, we assign a new and more reliable set of reference values and respective uncertainties for major, minor and a large group of trace elements of the nineteen investigated rock reference materials.  相似文献   

Managing Bay and Estuarine Ecosystems for Multiple Services     

Lisa A. Needles  Sarah E. Lester  Richard Ambrose  Anders Andren  Marc Beyeler  Michael S. Connor  James E. Eckman  Barry A. Costa-Pierce  Steven D. Gaines  Kevin D. Lafferty  Hunter S. Lenihan  Julia Parrish  Mark S. Peterson  Amy E. Scaroni  Judith S. Weis  Dean E. Wendt 《Estuaries and Coasts》2015,38(1):35-48

Managers are moving from a model of managing individual sectors, human activities, or ecosystem services to an ecosystem-based management (EBM) approach which attempts to balance the range of services provided by ecosystems. Applying EBM is often difficult due to inherent tradeoffs in managing for different services. This challenge particularly holds for estuarine systems, which have been heavily altered in most regions and are often subject to intense management interventions. Estuarine managers can often choose among a range of management tactics to enhance a particular service; although some management actions will result in strong tradeoffs, others may enhance multiple services simultaneously. Management of estuarine ecosystems could be improved by distinguishing between optimal management actions for enhancing multiple services and those that have severe tradeoffs. This requires a framework that evaluates tradeoff scenarios and identifies management actions likely to benefit multiple services. We created a management action-services matrix as a first step towards assessing tradeoffs and providing managers with a decision support tool. We found that management actions that restored or enhanced natural vegetation (e.g., salt marsh and mangroves) and some shellfish (particularly oysters and oyster reef habitat) benefited multiple services. In contrast, management actions such as desalination, salt pond creation, sand mining, and large container shipping had large net negative effects on several of the other services considered in the matrix. Our framework provides resource managers a simple way to inform EBM decisions and can also be used as a first step in more sophisticated approaches that model service delivery.  相似文献   

Pb isotope geochemistry of a massif-type anorthositic-charnockitic body: The Hidra Massif (Rogaland,S.W. Norway).     

D Weis  D Demaiffe 《Geochimica et cosmochimica acta》1983,47(8):1405-1413

The Hidra Massif (Rogaland complex, S.W. Norway) is a massif-type anorthositic-charnockitic body. It consists of undeformed anorthosites and leuconorites, grading into fine-grained jotunites at the contact with the granulite facies gneisses of the metamorphic envelope. A stockwork of charnockitic dykes cross-cuts the massif. The Pb isotopic compositions of the anorthosites and leuconorites are comparable or slightly less radiogenic than those of the jotunites (${}^{206}\text{Pb}{}^{204}\text{Pb}$ from 18.079 to 19.307,(${}^{207}\text{Pb}{}^{204}\text{Pb}$ from 15.568 to 15.657 and ${}^{208}\text{Pb}{}^{204}\text{Pb}$ from 37.617 to 38.493). These values are compatible with an upper mantle origin for the parental magma of jotunitic composition and for the plagioclasic cumulates, but show the incorporation of lower crustal material (U-depleted and thus less radiogenic). The charnockitic dykes have significantly less radiogenic Pb isotopic compositions (${}^{206}\text{Pb}{}^{204}\text{Pb}$ from 17.472 to 19.171, ${}^{207}\text{Pb}{}^{204}\text{Pb}$ from 15.489 to 15.620and ${}^{208}\text{Pb}{}^{204}\text{Pb}$ from 36.991 to 40.922) which can be explained by a larger proportion of lower crustal contamination material. The contaminant could be the granulite facies gneisses of the metamorphic envelope. This interpretation is compatible with the K-Rb relationships of these rocks and with the O and Sr isotopic geochemistry.The proportion of contaminating lead in the charnockitic dykes can be estimated at 55 ± 15% considering the border facies jotunite as the uncontaminated parental magma and the least radiogenic gneiss of the metamorphic envelope as the contaminant.  相似文献   

Pb isotopes in Ascension Island rocks: oceanic origin for the gabbroic to granitic plutonic xenoliths     

D. Weis 《Earth and Planetary Science Letters》1983,62(2):273-282

The Pb isotopic compositions and U and Pb concentrations of the lava series (alkali basalt to comendite) and of their plutonic xenoliths (gabbro to alkaline granite) of Ascension Island are reported. The data are used to evaluate the source of the xenoliths which formed two differentiation suites: the acidic and intermediate xenoliths together with most of the lavas on the one hand, and the gabbroic xenoliths and a basaltic tuff on the other hand. The Pb isotopic compositions imply a mantle origin for the source magmas of the xenoliths and confirm the possibility of generating granitic rocks in an oceanic environment by fractional crystallization of a mantle-derived magma whose geochemical and isotopic characteristics are comparable to the source magmas of oceanic island basalts.  相似文献   

The origin of epigenetic graphite: evidence from isotopes   总被引：1，自引：0，他引：1  

Paul L Weis  Irving Friedman  Jim P Gleason 《Geochimica et cosmochimica acta》1981,45(12):2325-2332

Stable carbon isotope ratios measured in syngenetic graphite, epigenetic graphite, and graphitic marble suggests that syngenetic graphite forms only by the metamorphism of carbonaceous detritus. Metamorphism of calcareous rocks with carbonaceous detritus is accompanied by an exchange of carbon between the two, which may result in large changes in isotopic composition of the non-carbonate phase but does not affect the relative proportions of the two reactants in the rock. Epigenetic graphite forms only from carbonaceous material or preexisting graphite. The reactions involved are the water gas reaction (C + H₂O → CO + H₂) at 800–900°C, and the Boudouard reaction (2CO → C + CO₂), which probably takes place at temperatures about 50–100°C lower.  相似文献   

Cadmium acclimation and limb regeneration in the fiddler crab, Uca pugilator: Sex differences     

Judith S. Weis 《Marine environmental research》1985,16(3):199-214

After multiple autotomy in the fiddler crab, Uca pugilator, cadmium retards limb regeneration and ecdysis. To study the effects of pre-exposure to lower levels of cadmium, groups were pre-exposed to 0·1, 0·5 or 1·0 mg liter^?1 for a week prior to autotomy. Crabs were then placed in 1·0 mg liter^?1 for regeneration. Pre-exposed groups were compared with groups of crabs which had not been pre-exposed to Cd. It was found that males pre-exposed to 0·5 mg liter^?1 regenerated more rapidly in 1·0 mg liter^?1 than those not pre-exposed. This phenomenon was not observed in females, in which none of the three pre-exposure concentrations were able to accelerate regeneration in 1·0 mg liter^?1 relative to those not pre-exposed. In the pre-exposed males in which regeneration was accelerated and was comparable to control levels, no accompanying decrease of time until molting was observed. Therefore, the protective effect of pre-exposure would seem to be on the regeneration processes themselves and is not dependent on the neuroendocrine system which controls the molt cycle.  相似文献   

Development of symbiosis-specific genes as biomarkers for the early detection of cnidarian-algal symbiosis breakdown   总被引：2，自引：0，他引：2  

Mitchelmore CL  Schwarz JA  Weis VM 《Marine environmental research》2002,54(3-5):345-349

Coral bleaching, i.e. the loss of dinoflagellate symbionts from cnidarian hosts, is occurring globally at increasing rates, scales, and severity. The significance of these bleaching events to the health of coral reef ecosystems is extreme, as bleached corals exhibit high mortality, reduced fecundity and productivity and increased susceptibility to disease. This decreased coral fitness leads to reef degradation and ultimately to the breakdown of the coral reef ecosystem. To date there has been little work describing the application of biomarkers to assess coral health. The most commonly applied biomarker is, in fact, the bleaching event itself. We are interested in developing early warning biomarkers that can detect coral stress before bleaching occurs. Recently, several genes that are likely to function in regulating interactions between cnidarians and their symbionts have been characterized, using the temperate sea anemone Anthopleura elegantissima as a model species. One "symbiosis gene" identified from the host genome, sym32, is expressed as a function of anemone symbiotic-state, where sym32 expression is higher in symbiotic cf. aposymbiotic (symbiont-free) anemones. Real-time quantitative RT-PCR suggested that the level of sym32 expression was correlated with the abundance of algae in the host. Furthermore, laboratory exposures of anemones to low levels of cadmium (0, 20, 100 microg(-1) CdCl2; 14 days), which caused no change in algal cell numbers, resulted in a down-regulation of sym32 compared to controls, indicating that sym32 expression may serve as a new sensitive early warning biomarker of cnidarian-algal symbiosis breakdown.  相似文献