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Topic: Isotopic fractionation

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	SAHRA - Isotopes & Hydrology
		Laboratory of Isotope Geochemistry at the University of Arizona, Dept. of Geosciences
		Environmental Isotope Laboratory at the University of Waterloo
		Gat, J.R., The isotopes of hydrogen and oxygen in precipitation, in Handbook of Environmental Isotope Geochemistry, vol.
	www.sahra.arizona.edu /programs/isotopes/oxygen.html (2029 words)

	Genesis Web Science Document H: Solar Wind Elemental and Isotopic Fractionation
		Isotopic fractionation therefore will be much smaller than elemental fractionation.
		Thus, if isotopic fractionation exists, different solar wind regimes would be expected to have different amounts of fractionation leading to interregime isotope variations.
		Thus, comparisons of isotopic abundances for elements widely separated in mass are important; consequently, measurements of C and Xe plus other noble gases, in different regimes have a high priority (Measurement objectives 4 and 6, proposal Table 1-2).
	www.gps.caltech.edu /genesis/DocumentH.html (1666 words)

	Isotopic Fractionation (Site not responding. Last check: 2007-10-10)
		Fractionation during the geochemical transfer of carbon in nature produces variation in the equilibrium distribution of the isotopes of carbon (12C, 13C and 14C).
		The extent of isotopic fractionation on the 14C/12C ratio which radiocarbon daters are seeking to measure accurately, is approximately double that for the measured 13C/12C ratio.
		In summary, then, isotopic fractionation refers to the fluctuation in the carbon isotope ratios as a result of natural biochemical processes as a function of their atomic mass (Taylor, 1987).
	www.c14dating.com /frac.html (534 words)

	Stable isotope - Wikipedia, the free encyclopedia
		Stable isotopes are chemical isotopes that are not radioactive.
		Stable isotopes of the same element have the same chemical characteristics and therefore behave almost identically.
		Stable isotopes have been used in botanical and plant biological investigations for many years, and more and more ecological and biological studies are finding stable isotopes (mostly carbon, nitrogen and oxygen) to be extremely useful.
	en.wikipedia.org /wiki/Isotopic_fractionation (319 words)

	Carbon isotope fractionation (data)
		Carbon isotope fractionation is dependent on the light climate experienced by the algal cell.
		Carbon isotope fractionation is affected by the nutritional status of the algal cells.
		With the exception of one field study of phytoplankton isotopic fractionation in a Norwegian fjord (Kukert and Riebesell 1998), research activities of the AWI group have focused on the analysis of isotope fractionation in monospecific laboratory cultures.
	www.nioz.nl /nioz_nl/ba9877cea8b00441f65b4b700cbcc396.php (1369 words)

	paleoxiso
		If conditions are not normalized, isotopic fractionation during dissolution will vary from sample to sample and all our data will just show that one day it was warmer in the lab than another day, or something else that we are not interested in.
		Isotope fractionation is the partial separation of isotopes of the same element during physical (e.g., evaporation) or chemical (e.g., precipitation reaction) processes.
		Isotope fractionation between two substances (such as the bicarbonate ion dissolved in water and carbonate) accompanying a specific process (such as the precipitation of calcite) is expressed in the fractionation factor (a):
	ethomas.web.wesleyan.edu /ees123/paleoxiso.htm (2739 words)

	Microbial Isotopic Fractionation of Perchlorate Chlorine -- Coleman et al. 69 (8): 4997 -- Applied and Environmental ... (Site not responding. Last check: 2007-10-10)
		Sulphur isotope fractionation in modern microbial mats and the evolution of the sulphur cycle.
		Variation in stable carbon isotope fractionation during aerobic degradation of phenol and benzoate by contaminant degrading bacteria.
		Chlorine isotope fractionation during reductive dechlorination of chlorinated ethenes by anaerobic bacteria.
	aem.asm.org /cgi/content/full/69/8/4997 (1988 words)

	Processing & Engineering \| Stable Isotopes Find a New Role in Process Analytical Technology \| Pharmaceutical ...
		Isotopic fractionation between light and heavy isotopes occurs when chemical reactions do not proceed to completion, or when multiple products are formed, and those isotopes are unevenly distributed among the reactants and products.
		Synthetic isotope fractionations are potential quantitative process monitors that could be used to integrate specific reaction variables that contribute to the isotopic composition of the synthetic product.
		Although the isotopic compositions of the starting materials used to produce the archived Topiramate samples were not controlled, the isotopic results were graphically grouped or “clustered” depending on the synthetic pathway used.
	www.pharmamanufacturing.com /articles/2005/277.html (1801 words)

	Chapter 2: Fundamentals of Isotope Geochemistry
		The magnitude of a kinetic isotope fractionation depends on the reaction pathway, the reaction rate, and the relative bond energies of the bonds being severed or formed by the reaction.
		Evaporation from an open-water surface fractionates the isotopes of hydrogen and oxygen in a manner which depends on a number of environmental parameters, the most important of which is the ambient humidity.
		is an additional diffusive (kinetic) isotope fractionation which results from the different diffusivities of the water molecules of various isotopic compositions in the liquid-air boundary layer (i.e., an additional fractionation caused by diffusion across the humidity gradient between the "equilibrium vapor layer" and the turbulently mixed vapor sublayer on Figure 2.6).
	wwwrcamnl.wr.usgs.gov /isoig/isopubs/itchch2.html (13621 words)

	Genesis Web Science Document A: Isotopic Composition of the Solar System
		In natural terrestrial and lunar matter, isotopic abundance variations arise from (a) radioactivity, (b) isotopic fractionation accompanying physical or chemical processes (evaporation, diffusion, precipitation, etc.), and (c) nuclear reactions (galactic cosmic rays, or to a lesser extent, solar flare ions for lunar samples).
		Knowledge of the initial elemental and isotopic abundances of volatile species is imperative for identifying evolutionary mechanisms that might have acted, whether the modeling is forward, from presumed compositions in primordial atmospheres, or backward from known compositions in contemporary atmospheres.
		Podosek F.A., Huneke J.C., Burnett D.S., and Wasserburg G.J. (1971) Isotopic composition of Xe and Kr in the lunar soil and solar wind.
	www.gps.caltech.edu /genesis/DocumentA.html (9405 words)

	Environmental Effects on Carbon Isotope Fractionation (Site not responding. Last check: 2007-10-10)
		It is obvious that if information on carbon isotopes is to be used to accurately interpret the geological record or determine source carbon, the complete range of factors influencing carbon isotope fractionation must be addressed.
		C ratios of organisms occur as the lighter isotope is taken up preferentially over the heavier isotope due to dissimilarities in physical and chemical properties in mass difference (Farquhar et al, 1989; Durako and Sackett, 1992; Criss, 1999).
		Stable carbon isotope fractionation by marine phytoplankton in response to daylength, growth rate, and CO availability.
	www.fiu.edu /~vcorne01/paper.htm (3054 words)

	Isotopic signature - Wikipedia, the free encyclopedia
		An isotopic signature (also isotopic fingerprint) is a ratio of stable or unstable isotopes of particular elements found in an investigated material.
		C isotope is important in distinguishing biosynthetized materials from man-made ones.
		The pursuit of isotopic and molecular fire tracers in the polar atmosphere and cryosphere
	en.wikipedia.org /wiki/Isotopic_signature (542 words)

	Spatial and Temporal Stable Isotopic Distribution on Mount McKinley
		H, the ratio of the like element isotopes change during phase transformations in a process called “fractionation.” The degree to which precipitation fractionates is a unique signature of the climate from which it is a consequence.
		The fundamental factors which control isotopic fractionation during precipitation (snow in particular) are: (1) Temperature of condensation, (2) Moisture source locations and conditions, (3) The rain-out effect, (4) The amount effect, (5) The altitude effect, and (6) Re-evaporation (7) Kinetic processes.
		The shift in fractionation rates could be the relict of changing thermal conditions within a singular air mass, or could be the result of two events characterized by different temperatures.
	instaar.colorado.edu /~vachon/Denali_writing.html (4426 words)

	Isotopic fractionation of carbon and nitrogen during the illicit processing of cocaine and heroin in South America
		Isotopic fractionation of carbon and nitrogen during the illicit processing of cocaine and heroin in South America
		Continuous-flow elemental analysis-isotope ratio mass spectrometry was utilized to measure changes in the stable isotope ratios of carbon and nitrogen for both cocaine (N=92) and heroin/morphine (N=81) exhibits derived from illicit manufacturing processes utilized by South American clandestine chemists.
		In contrast, nitrogen isotope fractionation for this conversion was 1‰.
	www.astm.org /JOURNALS/FORENSIC/PAGES/5104.htm (630 words)

	Compound-Specific Isotopic Fractionation Patterns Suggest Different Carbon Metabolisms among Chloroflexus-Like Bacteria ... (Site not responding. Last check: 2007-10-10)
		Ratios of carbon isotopes in microbial lipids as an indicator of substrate usage.
		Carbon isotopic fractionation in the biosynthesis of bacterial fatty acids.
		Carbon isotopic fractionation associated with lipid biosynthesis by a cyanobacterium: relevance for interpretation of biomarker records.
	aem.asm.org /cgi/content/full/69/10/6000 (2708 words)

	[22.02] Isotopic Fractionation and Dilution of CO on Titan (Site not responding. Last check: 2007-10-10)
		O, to be enriched relative to CO. However, the isotopic signature resulting from atmospheric evolution may be altered by photochemical reactions in the atmosphere of Titan.
		We investigate the possibility of isotopic fractionation and dilution using the Caltech/JPL one-dimensional kinetics model of Titan.
		The time constants for the isotopic exchange processes will be estimated by our model.
	www.aas.org /publications/baas/v32n3/dps2000/535.htm (276 words)

	Multiple sulfur isotope fractionations in biological systems: A case study with sulfate reducers and sulfur ... (Site not responding. Last check: 2007-10-10)
		This concentration is still large enough not to effect the fractionation produced by the organisms (Habicht and others, 2002).
		Fractionation factors used were taken from Rees (1973).
		Kemp A. W., and Thode, H. G., 1968, Mechanism of bacterial reduction of sulphate and of sulphite from isotope fractionation studies: Geochimica et Cosmochimica Acta, v.
	www.ajsonline.org /cgi/content/full/305/6-8/645 (5246 words)

	Isotopic fractionation of water during evaporation
		O and D/H ratios) of water in the natural environment provide a valuable tracer of the present-day global hydrologic cycle and a record of the climate over at least 400,000 years that is preserved in glacial ice.
		The interpretation of observed isotopic ratios in water vapor, rain, snow, and ice depends on our understanding of the processes (mainly phase changes) that produce isotopic fractionation.
		Whereas equilibrium isotopic fractionation is well understood, kinetic effects, or diffusion-controlled fractionation, has a limited experimental foundation.
	www.agu.org /pubs/crossref/2003/2003JD003597.shtml (379 words)

	Extraordinary isotopic fractionation in ozone photolysis
		Analysis of experimental ozone absorption spectra reveals that ultraviolet photolysis within the structured Huggins band yields extraordinary wavelength-dependent isotopic fractionation, oscillating between complete enrichment and complete depletion for changes of less than 2 nm in the excitation wavelength.
		Visible photolysis yields wavelength-dependent fractionation that varies from −300‰ to +300‰.
		O isotopologue-dependent variations as a function of altitude despite the fact that the extraordinary photolysis-induced isotopic fractionation effect is dampened in the atmosphere due to the integration over all excitation wavelengths.
	www.agu.org /pubs/crossref/2005/2005GL023160.shtml (226 words)

	isotopic - OneLook Dictionary Search
		Tip: Click on the first link on a line below to go directly to a page where "isotopic" is defined.
		adjective: of or relating to or having the relation of an isotope
		Phrases that include isotopic: isotopic abundances, isotopic analysis, isotopic dating, isotopic fractionation, isotopic tracer, more...
	www.onelook.com /?w=isotopic (130 words)

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