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Showing 1 to 20 of 181 for “"Isotope ratios"”.
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Isotope ratios in source determination of formaldehyde emissions
… It is possible to distinguish the 13C/12C isotope ratio of UF resins from the isotope ratio of plant biomass. Conditions during and after composite hot-pressing promote reactions that generate formaldehyde from wood and UF resin, and the kinetic isotope effect continuously lowers the …
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Lead isotope ratios in the Bayhorse mining district, Custer County, Idaho.
Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences.
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Inferring Extinct Reptilian Response To Global Warming: Insights From Modern Stable Isotope Ratios
… disconnected from the taxon of interest. Stable isotope geochemistry, however, provides an independent test. I analyzed stable isotope ratios (δ¹⁸O, δ¹³C) from enamel, providing new data on the connection between morphology, diet, and environment. I find a trophic separation in δ¹³C, and …
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Composition of fine and ultra-fine particles and source identification by stable isotope ratios
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1998.
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Anthropogenic Lead Deposition and Four National Parks in Poland as Determined by Lead Isotope Ratios
… pollution is accurately recorded by specific Pb isotope signatures, which differ from natural Pb isotopes. The objective of this project was to use <sup>206</sup>Pb/<sup>207</sup>Pb and <sup>206</sup>Pb/<sup>204</sup>Pb isotope ratios to differentiate between the anthropogenic Pb input and the …
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Understanding the evolution of compositional zoning in San Juan Volcanic Field ignimbrites using iron isotope ratios
… largely unknown. Here I present new iron (Fe) isotope ratio data along with 87Sr/86Sr ratios and major and trace elements for 37 samples from the SJVF with the goal of improved understanding of the origin of zoned ignimbrites. I sampled in detail the zoned 33.2 Ma Bonanza Tuff as well as two …
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Glacial-interglacial variations of the water masses in the southeast Atlantic Ocean derived from foraminiferal neodymium isotope ratios
… to trace these ambient changes is the stable isotope systematics of neodymium (given as εNd). In this study εNd data were measured on mixed planktic and bulk foraminifera from two gravity cores, GeoB8336-6 and GeoB8342-6, retrieved from the Cape Basin at water depths of 3524 and 3521 meters …
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Sulfur isotope ratios and the origin of the sulfide deposits in the Bathurst area of Northern New Brunswick
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Geology and Geophysics, 1959.
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Application of Hydrogen and Oxygen Isotope Ratios of Water to the Study of Evaporation, Palaeoclimate, and Ancient Marine Conditions
Triple-oxygen and hydrogen isotopes of water are critical to aid our understanding of the hydrological cycle on the modern and ancient Earth. As such, this thesis presents advancements in techniques and in the understanding of the isotopic behaviour of water that undergoes evaporation in different …
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Selenium Stable Isotope Ratios in Wetlands: Insights Into Biogeochemical Cycling and How a Diffusive Barrier Affects the Measured Fractionation Factor
… via reduction, sorption, and assimilation. Isotope fractionation studies can potentially distinguish reduction from other removal processes, and possibly quantify the amount of reduction, assuming that the correct isotope fractionation factor, alpha, is applied. Typically, alpha is …
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Critical zone (bio)geochemical reactivity and hydrologic transport recorded by the stable lithium isotope ratios of fluids draining upland watersheds
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2025-08-01
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An investigation into the viability of an infrared diagnostic instrument for measurement of CO<sub>2</sub> isotope ratios in breath
Stable CO<sub>2</sub> isotope ratio breath tests are established as a valuable tool in diagnostic and investigative medicine, with the potential to become more prominent in the future. The instrument conventionally used to measure the very small changes involved is an Isotope Ratio Mass …
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The high temperature geochemistry of vanadium: From isotope ratios in ocean island basalt to thermal diffusion processes at the core-mantle boundary
… ‰, the largest offsets among all metal stable isotope systems. If primitive meteorites represent the primary building blocks of the Earth, Earth’s interior must have a complementary “hidden reservoir” having light V isotope ratio. The two mostly likely reservoirs are the Earth’s deep mantle and …
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STABLE ISOTOPE RATIOS AS A PROXY FOR HUMAN GEOGRAPHIC PROVENANCE: BIOGEOGRAPHICAL EVIDENCE FROM THE 2H, 18O, AND 13C SIGNATURES IN MODERN HUMAN TEETH
… or do not yield immediate results. Stable isotope analysis of biogenic tissues such as tooth enamel and bone mineral has become a well‐recognized and increasingly important method for determining the provenance of human remains, and it has been used successfully in bioarchaeological studies …
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The Development of an Analytical Technique to Measure Stable and Radiogenic Strontium Isotope Ratios Using Thermal Ionization Mass Spectrometry with the Double Spike Method
… measure the n(87Sr)/n(86Sr) and n(88Sr)/n(86Sr) isotope ratios using a thermal ionization mass spectrometer. The results obtained for the SRM987 reference material using this technique are in agreement with published data. However, the results of IAPSO sea water standard revealed an enrichment in …
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The use of stable isotope ratios of carbon and nitrogen to elucidate pelagic marine foodwebs of the Benguela and Agulhas Bank regions of South Africa
Isotope assessments of foodweb relationships amongst pelagic organisms may be influenced by their lipid content, since lipids are more depleted in ¹³C than other biochemical compounds. This is particularly important for plankton which show a greater decrease in δ¹³C caused by the failure to remove …
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Assessing the effect of feather wear on carbon and nitrogen stable isotope ratios, and the use of stable isotopes to determine predator diets in the Namibian Islands marine protected area
The stable isotope (SI) approach is widely used in ecological research to tackle problems such as delineating food web structure or tracing the migratory origins of various organisms. This thesis first tested the widely accepted assumption that SI ratios are fixed in an inert tissue, and then used …
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Geochemical processes in the earth's mantle and the nature of crust-mantle interactions : evidence from studies of Nd and Sr isotope ratios in mantle-derived igneous rocks and lherzolite nodules
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980.
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Stable carbon and nitrogen isotope ratios in the shallow-water cape hake, merluccius capensis (castelnau) as indicators of trophic position and diet on the west and south coasts of South Africa
… of hake, therefore stable carbon and nitrogen isotope ratios were used to show the longer-term diet, integrated over the turnover time of the muscle tissue and bone collagen analysed. 13C/12C is 1-2%₀ higher in the tissues of a consumer than its diet (DeNiro and Epstein 1978), the difference in …
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