نتایج جستجو برای: isotopic
تعداد نتایج: 18280 فیلتر نتایج به سال:
We report Li isotopic measurements in seawater derived waters discharged from geothermal wells, thermal and submarine springs located in volcanic island arc areas in Guadeloupe (the Bouillante geothermal field) and Martinique (Lamentin plain and the Diamant areas). The lithium isotopic signatures of the geothermal fluids collected from deep reservoirs are homogeneous for a given site. However, ...
The concentration and isotopic composition of monochlorobenzene (MCB) was monitored in the plume of an anaerobic, contaminated aquifer in Bitterfeld, Germany. An enrichment in the carbon isotopic composition of more than 4 delta units was found at the fringes of the plume relative to the center (-26.5 %), suggesting the occurrence of in situ biodegradation of MCB. A similar enrichment was measu...
Although access to high-resolution mass spectrometry (MS), especially in the field of biomolecular MS, is becoming readily available due to recent advances in MS technology, the accompanied information on isotopic distribution in high-resolution spectra is not used at its full potential, mainly because of lack of knowledge and/or awareness. In this review, we give an insight into the practical ...
Inter-individual variation in diet within generalist animal populations is thought to be a widespread phenomenon but its potential causes are poorly known. Inter-individual variation can be amplified by the availability and use of allochthonous resources, i.e., resources coming from spatially distinct ecosystems. Using a wild population of arctic fox as a study model, we tested hypotheses that ...
Suitability of selected free-gas and dissolved-gas sampling containers for carbon isotopic analysis.
RATIONALE Storage trials were conducted for 2 to 3 months using a hydrocarbon and carbon dioxide gas mixture with known carbon isotopic composition to simulate typical hold times for gas samples prior to isotopic analysis. A range of containers (both pierced and unpierced) was periodically sampled to test for δ(13)C isotopic fractionation. METHODS Seventeen containers were tested for free-gas...
MOTIVATION In recent years stable isotopic labeling has become a standard approach for quantitative proteomic analyses. Among the many available isotopic labeling strategies, metabolic labeling is attractive for the excellent internal control it provides. However, analysis of data from metabolic labeling experiments can be complicated because the spacing between labeled and unlabeled forms of e...
Using the Solar Isotope Spectrometer (SIS) on the Advanced Composition Explorer (ACE), we have measured the isotopic composition of as many as eleven elements from He through Ni at energies of tens of MeV /nucleon in eleven solar energetic particle (SEP) events that have occurred since November 1997. We find that isotopic composition varies dramatically from event to event. For example, the 22N...
Recent AU :2 high-resolution Oligocene–Miocene oxygen isotopic records revealed a relatively transient, ca. 2myr period, 1m amplitude cyclicity in isotopic values (Oi and Mi events, respectively). Intriguingly, it has been suggested that these isotopic excursions in oceanic dO were linked to ephemeral growth and decay in Antarctic ice sheets. A great deal of effort in the palaeoceanography comm...
The isotopic composition of our Solar System reflects the blending of materials derived from numerous past nucleosynthetic events, each characterized by a distinct isotopic signature. We show that the isotopic compositions of elements spanning a large mass range in the earliest formed solids in our Solar System, calcium-aluminum-rich inclusions (CAIs), are uniform, and yet distinct from the ave...
[1] Isotopic hydrograph separation (IHS) to define sources of event and preevent water during hydrological episodes has greatly improved the understanding of water, solute, and contaminant transport to streams during recent decades. However, the large variation in snowmelt isotopic composition, caused by fractionation during melting, has impeded an accurate separation of streamflow during sprin...
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