Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (30)
- Beitrag zu einem Tagungsband (4)
- Posterpräsentation (4)
- Vortrag (3)
- Buchkapitel (1)
Schlagworte
- IDMS (7)
- TIMS (6)
- ICPMS (4)
- Reference materials (4)
- Isotope reference materials (3)
- Mass spectrometry (3)
- Atomic weight (2)
- Basidiomycetes (2)
- Cadmium (2)
- Delta reference materials (2)
- ICP-MS (2)
- IRM (2)
- IRMS (2)
- Milk (2)
- Nitrogen (2)
- Provenance studies (2)
- Stable isotopes (2)
- 15N2 fixation (1)
- 16S rRNA (1)
- Accelerator mass spectrometry (1)
- Analyte-matrix separation (1)
- Analytical uncertainty (1)
- Archaeometry (1)
- Authenticity (1)
- Biocide (1)
- Bodenanalyse (1)
- Boron isotope variations (1)
- Boron isotopes (1)
- Boron isotopes in food (1)
- Branching ratio (1)
- CRM (1)
- Calix[8]arenes (1)
- Casein standard (1)
- Cattle (1)
- Certification (1)
- Certified reference material (1)
- Comparability (1)
- Copper (1)
- Cu-64 (1)
- Dairy cows (1)
- Delta-RM (1)
- Delta-scale (1)
- Determination of metrology of new cadmium atomic weight (1)
- Diazotroph (1)
- ERM (1)
- Elemental analyser (1)
- Erythrocytes (1)
- FTIR-ATR spectroscopy (1)
- Faecal monitoring (1)
- Feed (1)
- Feeding regime (1)
- Fishmeal (1)
- Food (1)
- Fossil fuel (1)
- Full-factorial experimental plan (1)
- Fungal-bacterial interaction (1)
- Fungalbacterial interaction (1)
- Fungi (1)
- Heterocycles (1)
- Hypholoma fasciculare (1)
- ICP-IDMS (1)
- ICP-OES (1)
- INAA (1)
- Isotope (1)
- Isotope abundance (1)
- Isotope dilution (1)
- Isotope labeling (1)
- Isotope ratio (1)
- Isotopic Reference Material (1)
- Isotopic abundance variations (1)
- Isotopic composition (1)
- Königswasserextraktion (1)
- Low sulfur (1)
- MC-ICP-MS (1)
- Magnesium (1)
- Magnesium absorption (1)
- Measurement uncertainty (1)
- Metrology (1)
- Microbial interaction (1)
- Multi-collector ICP-MS (1)
- Multi-element screening (1)
- Multicollector inductively coupled plasma mass spectrometry (1)
- N2 assimilation (1)
- NTD (1)
- Neutron transmutation doping (1)
- Nickel (1)
- PLFA (1)
- Pb isotope ratio thermal ionization mass spectrometry (1)
- Phosphates (1)
- Primary Isotopic Reference Material (1)
- Proteobacteria (1)
- Provenance (1)
- RBS (1)
- Reference material (1)
- Reference procedure (1)
- Review (1)
- S K-edge X-ray absorption near edge spectroscopy (XANES) (1)
- SF-ICP-MS (1)
- SY-XRF (1)
- Schwermetallbestimmung (1)
- Soil (1)
- Stable isotope (1)
- Stable isotope probing (1)
- Stereochemistry (1)
- Sulfate-esters (1)
- Sulfur oxidation status (1)
- Surface analysis (1)
- Synthetic isotope mixtures (1)
- Synthetic mixtures (1)
- Thermal ionization mass spectrometry (1)
- Traceability (1)
- Unsicherheitsvergleiche (1)
- Urinary monitoring (1)
- Urine (1)
- VPDB (1)
- Vario EL III (1)
- Water (1)
- Wood decomposing basidiomycetes (1)
- Wood decomposition (1)
- Wood preservative (1)
- XRF (1)
- Zinc (1)
- multi-collector (1)
- reference material (1)
- uncertainty budget (1)
Eingeladener Vortrag
- nein (3)
Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very heavy values generate a compositionally unique material. These compositions trace the presence of guano in natural ecosystems and its use as fertilizer in present and past agriculture.
Isotope reference materials are needed to calibrate and validate analytical procedures used for the determination of isotope amount ratios, procedurally defined isotope ratios or so-called δ values. In contrast to the huge analytical progress in isotope ratio analytics, the production of isotope reference materials has not kept pace with the increasing needs of isotope analysts. Three representative isotope systems are used to explain the technical and non-technical difficulties and drawbacks, on one hand, and to demonstrate what can be achieved at its best, on the other hand. A clear statement is given that new isotope reference materials are needed to obtain traceable and thus comparable data, which is essential for all kinds of isotope research. The range of available isotope reference materials and δ reference materials should be increased and matrix reference materials certified for isotope compositions or δ values, which do not exist yet, should be provided.
A modified Pb–matrix separation procedure using NH4HCO3 solution as eluent has been developed and validated for determination of Pb isotope amount ratios by thermal ionization mass spectrometry. The procedure is based on chromatographic separation using the Pb·Spec resin and an in-house-prepared NH4HCO3 solution serving as eluent. The advantages of this eluent are low Pb blanks (<40 pgmL-1) and the property that NH4HCO3 can be easily removed by use of a heating step (>60 °C). Pb recovery is >95 % for water samples. For archaeological silver samples, however, the Pb recovery is reduced to approximately 50 %, but causes no bias in the determination of Pb isotope amount ratios. The validated procedure was used to determine lead isotope amount ratios in Trojan silver artefacts with expanded uncertainties (k=2) <0.09 %.
The white-rot fungus Hypholoma fasciculare coexists with a bacterial community that uses low-molecular weight carbon sources provided by fungal, extracellular enzyme activities. Since fungal development on wood is limited by the availability of nitrogen (N), bacteria could contribute to the N supply. To prove or disapprove an interaction in terms of N transfer, N sources of the fungus and the coexisting bacterial isolates were investigated, and the bacterial N2 fixation was quantified. Fungal, fungal—bacterial and bacterial wood decomposition was analysed by Fourier transform infrared spectroscopy (FTIR), mass loss and surface pH. Microbial N preferences were investigated by elemental analysis isotope ratio mass spectrometry (IRMS). In addition, diazotrophic activity was explored after cultivation under a 15N2/O2 atmosphere. Decomposition was similar with and without bacteria and both H. fasciculare and coexisting bacteria preferred reduced N species, such as urea, ammonium and organic N. In most of the bacteria, the 15N abundance in the biomass increased significantly but to a low extent if they were cultivated under a 15N2/O2 atmosphere. This effect is considered an artefact and attributed to adsorption rather than to bacterial N2 fixation activity. Hence, the bacteria coexisting with H. fasciculare rather competed for the same N sources than supported fungal N supply by diazotrophic activity.
Nitrogen sources of oligoporus placenta and trametes versicolor evaluated in a 2³ experimental plan
(2012)
Four full-factorial 2³ experimental plans were applied to evaluate the nitrogen (N) sources of Oligoporus placenta and Trametes versicolor and their interaction with the atmospheric N2-assimilating bacterium Beijerinckia acida. The effects of N from peptone, of sapwood and of N from gaseous N2 on fungal, bacterial and fungal–bacterial activity were investigated. The activities were determined by quantification of biomass, formation of CO2, consumption of O2 and laccase activity. The significance of each effect was tested according to t-test recommendation.
The activity of both fungi was enhanced by peptone rather than sapwood or gaseous N2. Nevertheless, comparative studies under an N2-free gas mixture as well as under air revealed that the presence of N2 affected bacterial growth and bacterial–fungal cocultivations. Elemental analysis isotope ratio mass spectrometry (IRMS) of the bacterial and fungal biomass enabled estimation of N transfer and underlined gaseous N2 as requisite for fungal–bacterial interactions. Combining full-factorial experimental plans with an analytical set-up comprising gas chromatography, IRMS and enzymatic activity allowed synergistic effects to be revealed, fungal N sources to be traced, and symbiotic fungal–bacterial interactions to be investigated.
The main wood degraders in aerobic terrestrial ecosystems belong to the white- and brown-rot fungi, where their biomass can be created on wood decay only. However, total sulfur (S) concentration in wood is very low and only little is known about the different sulfur compounds in wood today. Sulfur-starved brown-rot fungi Gloeophyllum trabeum and Oligoporus placenta were incubated on sterilized pine wood blocks whereas Lentinus cyathiformis and the white-rot fungi Trametes versicolor were incubated on sterilized beech wood blocks. After 19 weeks of incubation, the S oxidation status was analyzed in wood, in degraded wood, and in biomass of wood-degrading fungi by synchrotron based S K-edge XANES, and total S and sulfate were quantified. Total sulfur and sulfate content in pine wood blocks were approximately 50 and 1 µg g-1, respectively, while in beech wood approximately 100 and 20 µg g-1 were found, respectively. Sulfur in beech was dominated by sulfate-esters. In contrast, pine wood also contained larger amounts of reduced S. Three out of four selected fungi caused a reduction of the S oxidation state in wood from oxidized S (sulfate-ester, sulfate) to intermediate S (sulfonate, sulfoxide) or reduced S (thiols, e.g., proteins, peptides, enzyme cofactors). Only O. placenta shifted thiol to sulfonate. Growth experiments of these fungi on selective minimal media showed that in particular cysteine (thiol), sulfonates, and sulfate enhanced total mycelium growth. Consequently, wood-degrading fungi were able to utilize a large variety of different wood S sources for growth but preferentially transformed in vivo sulfate-esters and thiol into biomass structures.
In this study, an analytical procedure for multi-element screening of 40 elements in milk and feed samples was developed. Three different digestion and two different calibration methods were tested for the best suitability. The analytical procedure for the quantification of minor and trace elements is based on sector field ICP-MS (SF-ICP-MS). The method validation revealed good agreement between the determined elemental mass fractions and the certified values of two milk and three feed reference materials. Milk samples of dairy cows at different feeding regimes were collected from two different farms. The results of our study showed significant differences of nine elemental mass fractions (Li, P, Mn, Co, Cu, Rb, Sr, Br, I) between milk from the two locations. Further, a correlation between the elemental mass fractions of milk and the ingested feed and water was observed.
Isotope ratio mass spectrometry (IRMS) is an advanced method to investigate carbon (C) and nitrogen (N) in organic samples. In particular, the N content, its isotope signature and the C/N ratio reveal important facts of nutrient cycling, niche separation and ecological food webs. In this study, the characteristics of N turnover of wood decomposing microorganisms were investigated.
The growth of the white rot causing basidiomycete Trametes versicolor is enhanced after addition of ammonia or urea, whereas the brown rot causing Oligoporus placenta is not accelerated. In addition, an interaction of each fungus with atmospheric N2 assimilating (diazotrophic) bacteria was investigated. Cultivation experiments with a gas mixture of 15N2/O2 and subsequent IRMS analysis of dry biomass of the diazotrophs Azotobacter croococcum, Beijerinckia acida and Novosphingobium nitrogenifigens revealed that they assimilated up to 12% of their N from N2. The experiments reflected N availability as a prerequisite for efficient growth of decomposing basidiomycetes and diazotrophs. Fungal–bacterial co-cultivation experiments showed that depending on the growth characteristics and bacterial N2 assimilation activity N is transferred from certain bacteria into fungal biomass. Thus, the experiments gave a first indication of an interaction between wood decomposing basidiomycetes and diazotrophs, which is a novel pathway of fungal N acquisition.
Boron isotope studies on technical materials and geological and environmental samples are one hot topic in nowadays isotope research. Provenance studies of artefacts, food and other products might become another one, as several recent studies demonstrate. Typically boron isotope determinations have been carried out by TIMS. To open up this research field to a broader scientific community we developed two analytical procedures for boron isotope determinations based on single collector SF-ICPMS combined with a sample preparation procedure consisting of dry-ashing and a three step ion chromatographic boron-matrix separation. The developed procedures consist of one low resolution (LR) and one medium resolution (MR) procedure. The repeatability for the δ11B determination in three independently measured aliquots lies between 0.2 and 0.8‰ for the LR procedure and between 0.3 and 1.5‰ for the MR procedure. The expanded uncertainties with a coverage factor of k=2 range between 1.4 and 1.6‰ for the LR procedure and between 2.9 and 3.2‰ for the MR procedure. The accuracy, expressed as average deviation from the reference values, is 0.43‰ for the LR procedure and 0.33‰ for the MR procedure. To test the practicability of the procedures the matrix tolerance has been investigated as well and was found to be up to 2 mg kg-1 of alkaline and alkaline earth elements in the final measurement solution containing 100 µg kg-1 boron. Thus a highly efficient matrix separation for SF-ICPMS boron isotope determinations is required, similar to TIMS.