نتایج جستجو برای: stable isotope geochemistry
تعداد نتایج: 287576 فیلتر نتایج به سال:
The use of stable isotopes to solve biogeochemical problems in ecosystem analysis is increasing rapidly because stable isotope data can contribute both source-sink (tracer) and process information: The elements C, N, S, H, and all have more than one isotope, and isotopic compositions of natural materials can be measured with great precision with a mass spectrometer. Isotopic compositions change...
The characterization of metal release and attenuation in mining waste rock drainage has traditionally relied upon an array of mineralogical and geochemical techniques. Recent advances in analytical instrumentation now allow robust measurements of minute variations in the isotopic composition of metals in environmental samples, which have become a powerful new tracer of their fate. Here we provi...
The use of multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for trace metal stable isotope analysis is well established within geochemistry, essentially since the conception of such instruments. The utilization of this high precision technique in medical and life science research has only just begun, however, and the scope of applications is vast, from diagnosis to me...
Isotope ratio monitoring following on-line combustion is a new method in gas chromatography/mass spectrometry (GC/MS) that allows the ratios of abundances of stable isotopes of elements such as carbon and nitrogen to be determined for individual compounds introduced via a gas chromatograph. It is the first combustion method that allows direct measurement of isotope ratios of individual molecula...
Compound-specific isotope analysis (CSIA) by isotope ratio mass spectrometry (IRMS) following on-line combustion (C) of compounds separated by gas chromatography (GC) is a relatively young analytical method. Due to its ability to measure isotope distribution at natural abundance level with great accuracy and high precision, GC-C-IRMS has increasingly become the method of choice in authenticity ...
Mass spectrometry is fundamental to measurements of isotope ratios for applications in isotope geochemistry, geochronology, and cosmochemistry. Magnetic-sector mass spectrometers are most common because these provide the best precision in isotope ratio measurements. Where the highest precision is desired, chemical separation followed by mass spectrometric analysis is carried out with gas (noble...
cosmic rays in the upper troposphere (9000 meters to 15000 meters) initiate the followingnuclear chemical reaction: 1n + 14n => 14c + 1h. previous research has shown a strong effect of latitude onthe abundance of neutrons from cosmic rays. however, to date, there has been little exploration of therelationship between the latitude effect for cosmic-ray neutrons and latitudinal variations of stab...
Several transitions of Lower to Middle Turonian pelagic marl–limestone-cycles into Oceanic Red Beds were studied at high resolution to gain a better understanding of the Tethyan marine system before and during red bed initiation and development. Samples were analysed for mineralogy, geochemistry, and stable isotope composition. In particular, carbonate geochemistry of diagenetically largely una...
introduction one of the first principles in the formation of a reserve is mineralogical, construction and mineral textures studies and investigation of paragenetic relations in the ore minerals. in addition, to petrographic studies, isotopic investigates have wide applications in economic geology. in general, copper isotope variability in primary (high temperature) mineralization forms a tight ...
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