Stable isotope ratio

About: Stable isotope ratio is a research topic. Over the lifetime, 10586 publications have been published within this topic receiving 390729 citations.

Stable isotopes in precipitation

Abstract: In chapter 2 the isotopic fractionation of water in some simple condensation-evaporation processes are considered quantitatively on the basis of the fractionation factors given in section 1.2. The condensation temperature is an important parameter, which has got some glaciological applications. The temperature effect (the δ's decreasing with temperature) together with varying evaporation and exchange appear in the “amount effect” as high δ's in sparse rain. The relative deuterium-oxygen-18 fractionation is not quite simple. If the relative deviations from the standard water (S.M.O.W.) are called δ D and δ 18 , the best linear approximation is δ D = 8 δ 18 . Chapter 3 gives some qualitative considerations on non-equilibrium (fast) processes. Kinetic effects have heavy bearings upon the effective fractionation factors. Such effects have only been demonstrated clearly in evaporation processes, but may also influence condensation processes. The quantity d = δ D −8 δ 18 is used as an index for non-equilibrium conditions. The stable isotope data from the world wide I.A.E.A.-W.M.O. precipitation survey are discussed in chapter 4. The unweighted mean annual composition of rain at tropical island stations fits the line δ D = 4.6 δ 18 indicating a first stage equilibrium condensation from vapour evaporated in a non-equilibrium process. Regional characteristics appear in the weighted means. The Northern hemisphere continental stations, except African and Near East, fit the line δ D = 8.0 δ 18 + 10 as far as the weighted means are concerned (δ D = 8.1 δ 18 + 11 for the unweighted) corresponding to an equilibrium Rayleigh condensation from vapour, evaporated in a non-equilibrium process from S.M.O.W. The departure from equilibrium vapour seems even higher in the rest of the investigated part of the world. At most stations the δ D and varies linearily with δ 18 with a slope close to 8, only at two stations higher than 8, at several lower than 8 (mainly connected with relatively dry climates). Considerable variations in the isotopic composition of monthly precipitation occur at most stations. At low latitudes the amount effect accounts for the variations, whereas seasonal variation at high latitudes is ascribed to the temperature effect. Tokyo is an example of a mid latitude station influenced by both effects. Some possible hydrological applications are outlined in chapter 5. DOI: 10.1111/j.2153-3490.1964.tb00181.x

Stable isotopes in ecosystem studies

Abstract: 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 in predictable ways as elements cycle through the biosphere. These changes have been exploited by geochemists to understand the global elemental cycles. Ecologists have not until quite recently employed these techniques. The reasons for this are, first, that most ecologists do not have the background in chemistry and geochemistry to be fully aware of the possibilities for exploiting the natural variations in stable isotopic compositions, and second, that stable isotope ratio measurements require equipment not normally available to ecologists. This is unfortunate because some of the more intractable problems in ecology can be profitably addressed using stable isotope measurements. Stable isotopes are ideally suited to increase our understanding of element cycles in ecosystems. This review is written for ecologists who would like to learn more about how stable isotope analyses have been and can be used in ecosystem studies. We begin with an explanation of isotope terminology and fractionation, then summarize isotopic distributions in the C, N, and S biogeochemical cycles, and conclude with five case studies that show how stable isotope measurements can provide crucial information for ecosystem analysis. We restrict this review to studies of natural variations in C, N, and S isotopic abundances, cxcluding from consideration ~5N enrichment studies and hydrogen and oxygen isotope studies. Our focus on C, N, and S derives in part from our

Environmental Isotopes in Hydrogeology

Abstract: The Environmental Isotopes Environmental Isotopes in Hydrogeology Stable Isotopes: Standards and Measurement Isotope Ratio Mass Spectrometry Radioisotopes Isotope Fractionation Isotope Fractionation (a), Enrichment (e), and Separation (D) Tracing the Hydrological Cycle Craig's Meteoric Relationship in Global Fresh Waters Partitioning of Isotopes Through the Hydrological Cycle Condensation, Precipitation, and the Meteoric Water Line A Closer Look at Rayleigh Distillation Effects of Extreme Evaporation Precipitation The T - d18O Correlation in Precipitation Local Effects on T - d18O Ice Cores and Paleotemperature Groundwater Recharge in Temperate Climates Recharge in Arid Regions Recharge from River-Connected Aquifers Hydrograph Separation in Catchment Studies Groundwater Mixing Tracing the Carbon Cycle Evolution of Carbon in Groundwaters Carbonate Geochemistry Carbon-13 in the Carbonate System Dissolved Organic Carbon Methane in Groundwaters Isotopic Composition of Carbonates Chapter 6. Groundwater Quality Sulphate, Sulphide and the Sulphur Cycle Nitrogen Cycles in Rural Watersheds The "Fuhrberger Feld" Study Source of Chloride Salinity Landfill Leachates Degredation of Chloro-organics and Hydrocarbon Sensitivity of Groundwater to Contamination Summary of Isotopes in Contaminant Hydrology Identifying and Dating Modern Groundwaters The "Age" of Groundwater Stable Isotopes Tritium in Precipitation Dating Groundwaters with Tritium Groundwater Dating with 3H -3He Chlorofluorocarbons (CFCs) Thermonuclear 36Cl Detecting Modern Groundwaters with 85Kr Submodern Groundwater Age Dating Old Groundwaters Stable Isotopes and Paleogroundwaters Groundwater Dating with Radiocarbon Correction for Carbonate Dissolution Some Additional Complications to 14C Dating 14C Dating with Dissolved Organic Carbon (DOC) Case Studies for 14C dating with DOC and DIC Chlorine-36 and Very Old Groundwater The Uranium Decay Series Water-Rock Interaction Mechanisms of Isotope Exchange High Temperature Systems Low Temperature Water-Rock Interaction Strontium Isotopes in Water and Rock Isotope Exchange in Gas-Water Reactions High pH Groundwaters-The Effect of Cement Reactions Field Methods for Sampling Groundwater Water in the Unsaturated Zone Precipitation Gases Geochemistry References Index Each chapter has Problems sections.

Stable isotope geochemistry

Abstract: Theoretical and Experimental Principles.- Isotope Fractionation Processes of Selected Elements.- Variations of Stable Isotope Ratios in Nature.