The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abundance of such stable isotopes can be measured experimentally (isotope analysis), yielding an isotope ratio that can be used as a research tool. Theoretically, such stable isotopes could include the radiogenic daughter products of radioactive decay, used in radiometric dating. However, the expression stable-isotope ratio is preferably used to refer to isotopes whose relative abundances are affected by isotope fractionation in nature. This field is termed stable isotope geochemistry.
Isotope fractionation
Measurement of the ratios of naturally occurring stable isotopes (isotope analysis) plays an important role in isotope geochemistry, but stable isotopes (mostly hydrogen, carbon, nitrogen, oxygen and sulfur) are also finding uses in ecological and biological studies. Other workers have used oxygen isotope ratios to reconstruct historical atmospheric temperatures, making them important tools for paleoclimatology.
These isotope systems for lighter elements that exhibit more than one primordial isotope for each element have been under investigation for many years in order to study processes of isotope fractionation in natural systems. The long history of study of these elements is in part because the proportions of stable isotopes in these light and volatile elements is relatively easy to measure. However, recent advances in isotope ratio mass spectrometry (i.e. multiple-collector inductively coupled plasma mass spectrometry) now enable the measurement of isotope ratios in heavier stable elements, such as iron, copper, zinc, molybdenum, etc.
The variations in oxygen and hydrogen isotope ratios have applications in hydrology since most samples lie between two extremes, ocean water and Arctic/Antarctic snow.
Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.
La géologie isotopique est une branche de la géologie, apparentée à la géochimie, qui exploite l'étude des isotopes stables et radioactifs présents sur Terre pour en étudier la composition et les variations au cours des temps géologiques. À l'origine, la géologie isotopique a consisté à utiliser les connaissances concernant la radioactivité afin de dater des roches et des minéraux. Cette discipline, au carrefour de la géologie et de la physique nucléaire, s'est surtout illustrée par ses méthodes de datation absolue.
The environmental isotopes are a subset of isotopes, both stable and radioactive, which are the object of isotope geochemistry. They are primarily used as tracers to see how things move around within the ocean-atmosphere system, within terrestrial biomes, within the Earth's surface, and between these broad domains. Chemical elements are defined by their number of protons, but the mass of the atom is determined by the number of protons and neutrons in the nucleus.
L'oxygène 18, noté O, est l'isotope de l'oxygène dont le nombre de masse est égal à 18 : son noyau atomique compte et avec un spin 0+ pour une masse atomique de . Il est caractérisé par un excès de masse de et une énergie de liaison nucléaire par nucléon de . C'est un isotope stable. L'oxygène naturel en contient 0,205 %. L'oxygène 18 est utilisé en radiopharmacologie sous forme d'eau enrichie en espèces pour produire, par bombardement de protons — ions hydrogène — accélérés dans un cyclotron ou dans un accélérateur linéaire, du , lequel est, par exemple, utilisé sous forme de , noté , dans le cadre de la tomographie par émission de positons.
Understanding process and role of biomineralization (minerals formed by living organisms) in context of Earth's evolution,global chemical cycles, climatic changes and remediation.
In systems biology, proteomics represents an essential pillar. The understanding of protein function and regulation provides key information to decipher the complexity of living systems. Proteomic tec
The aim of this course is to treat three of the major techniques for structural characterization of molecules: mass spectrometry, NMR, and X-ray techniques.
Explore les méthodes d'analyse des communautés microbiennes, y compris le FISH, le PCR, les isotopes stables et la génomique monocellulaire, pour relier les fonctions aux cellules individuelles.
Time series analyses of solute concentrations in streamwater and precipitation are powerful tools for unraveling the interplay of hydrological and biogeochemical processes at the catchment scale. While such datasets are available for many sites around the ...
Nature Portfolio2024
, , , ,
The two-step electron transfer during bacterial reduction of UVI to UIV is typically accompanied by mass-independent fractionation of the 238U and 235U isotopes, whereby the heavy isotope accumulates in the reduced product. However, the role of the UV inte ...
2024
Sorption of mercury (Hg) in soils is suggested to be predominantly associated with organic matter (OM). However, there is a growing collection of research that suggests that clay minerals and oxides are also important solid phases for the sorption of solu ...