Filters: Tags: Isotope fractionation (X)17 results (122ms)
Mercury isotopic composition of hydrothermal systems in the Yellowstone Plateau volcanic field and Guaymas Basin sea-floor rift
To characterize mercury (Hg) isotopes and isotopic fractionation in hydrothermal systems we analyzed fluid and precipitate samples from hot springs in the Yellowstone Plateau volcanic field and vent chimney samples from the Guaymas Basin sea-floor rift. These samples provide an initial indication of the variability in Hg isotopic composition among marine and continental hydrothermal systems that are controlled predominantly by mantle-derived magmas. Fluid samples from Ojo Caliente hot spring in Yellowstone range in δ202Hg from − 1.02‰ to 0.58‰ (± 0.11‰, 2SD) and solid precipitate samples from Guaymas Basin range in δ202Hg from − 0.37‰ to − 0.01‰ (± 0.14‰, 2SD). Fluid samples from Ojo Caliente display mass-dependent...
Uranium-series disequilibrium, sedimentation, diatom frustules, and paleoclimate change in Lake Baikal
Sr/Ca, U/Ca and delta super(18)O records in recent massive corals from Bermuda: relationships with sea surface temperature
Geochemical Correction of Carbon-14 in Dissolved Inorganic Carbon used for Groundwater Age Dating in the Glacial Aquifer System, Conterminous United States
Data provided here describe geochemical correction of carbon-14 in dissolved inorganic carbon (DIC) for groundwater age dating. Datasets include major ion chemistry of groundwater samples, model parameter inputs, and final corrected carbon-14 in DIC. Geochemical correction was completed in two phases: determination of reactive phase mole transfers through an inverse geochemical model (PHREEQC; Parkhurst and Appleo, 1992) and tracking of isotopic mass transfer among phases (NetpathXL; Parkhusrtand Charlton, 2008). Parkhurst, D.L., and Appelo, C.A.J., 2013, Description of input and examples for PHREEQC version 3—A computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical...
Carbonate deposition, Pyramid Lake subbasin, Nevada: 4. Comparison of the stable isotope values of carbonate deposits (tufas) and the Lahontan Lake-level record
Recent advances in mass spectrometry have allowed isotope scientists to precisely determine stable isotope variations in the metallic elements. Biologically influenced and truly inorganic isotope fractionation processes have been demonstrated over the mass range of metals. This Elements issue provides an overview of the application of metal stable isotopes to low-temperature systems, which extend across the borders of several science disciplines: geology, hydrology, biology, environmental science, and biomedicine. Information on instrumentation, fractionation processes, data-reporting terminology, and reference materials presented here will help the reader to better understand this rapidly evolving field.
Selenium isotope geochemistry: A new approach to characterizing the environmental chemistry of selenium. Final report
Separation of kinetic and metabolic isotope effects in carbon-13 records preserved in reef coral skeletons
Middle Holocene dry climate caused by change in atmospheric circulation patterns: Evidence from lake levels and stable isotopes
Higher plants induce chemical reactions in the rhizosphere, facilitating metal uptake by roots. Fractionation of the isotopes in nutrients such as calcium, iron, magnesium, and zinc produces a stable isotope composition in the plants that generally differs from that of the growth medium. Isotope fractionation also occurs during transport of the metals within most plants, but its extent depends on plant species and on the metal, in particular, on the metal's redox state and what ligand it is bound to. The metal stable isotope variations observed in plants create an isotope signature of life at the Earth's surface, contributing substantially to our understanding of metal cycling processes in the environment and in...
Sr/Ca, U/Ca and delta super(18)O records in Recent massive corals from Bermuda: relationships with sea surface temperature