isotopic techniques

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• Isotopic labeling — (or isotopic labelling) is a technique for tracking the passage of a sample of substance through a system. The substance is labeled by including unusual isotopes in its chemical composition. If these unusual isotopes are later detected in a… …   Wikipedia

• Petroleum — For other uses, see Petroleum (disambiguation). Proven world oil reserves, 2009 …   Wikipedia

• Water cycle — The Earth s water is always in movement, and the water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Since the water cycle is truly a cycle, there is no… …   Wikipedia

• Nubian Sandstone Aquifer System — The Nubian Sandstone Aquifer System (NSAS) is the world’s largest known fossil water aquifer system. It is located underground in the Eastern end of the Sahara Desert and spans the political boundaries of four countries in north eastern… …   Wikipedia

• Jan Veizer — Ján Veizer, born in Slovakia, is an emeritus professor of Earth Sciences at the University of Ottawa and holder of the NSERC/Noranda/CIFAR Industrial Chair in Earth System Isotope and Environmental Geochemistry. He is an award winning isotope… …   Wikipedia

• COHN, MILDRED — (1913– ), U.S. physical and biochemist. Cohn was born in New York City and earned a B.A. from Hunter College and Ph.D. in physical chemistry from Columbia University. Her life long interests were metabolism and enzyme mechanisms, and she was a… …   Encyclopedia of Judaism

• isotope — isotopic /uy seuh top ik/, adj. isotopically, adv. /uy seuh tohp /, n. Chem. any of two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number, but having different numbers of neutrons in… …   Universalium

• dating — I In geology and archaeology, the process of determining an object s or event s place within a chronological scheme. Scientists may use either relative dating, in which items are sequenced on the basis of stratigraphic clues (see stratigraphy) or …   Universalium

• geology — /jee ol euh jee/, n., pl. geologies. 1. the science that deals with the dynamics and physical history of the earth, the rocks of which it is composed, and the physical, chemical, and biological changes that the earth has undergone or is… …   Universalium

• Earth Sciences — ▪ 2009 Introduction Geology and Geochemistry       The theme of the 33rd International Geological Congress, which was held in Norway in August 2008, was “Earth System Science: Foundation for Sustainable Development.” It was attended by nearly… …   Universalium

• mass spectrometry — or mass spectroscopy Analytic technique by which chemical substances are identified by sorting gaseous ions by mass using electric and magnetic fields. A mass spectrometer uses electrical means to detect the sorted ions, while a mass spectrograph …   Universalium