Environmental isotopes, such as oxygen-18 and deuterium, have been used increasingly to separate stormflow into its event and pre-event components in order to elucidate the sources, pathways and residence times of water in drainage basins
. The hydrological processes that have been invoked to explain the observed isotopic response of streamflow to rainfall and snowmelt inputs in various environments are reviewed. This paper summarizes the environmental isotope hydrograph separation technique
and provides a broad review of the results of isotope hydrograph separations conducted around the world.
Groundwater hydrology and stable isotope analysis of an open-system pingo in northwestern Mongolia
Cold area ; Hydrogeology ; Ice core ; Isotope analysis ; Mongolia ; Periglacial features ; Permafrost ; Pingo ; Underground water
the centre of Mongot Pingo, and ice cores were analysed for stable isotopes and chemical composition. Two different stable isotope patterns in separate ice sections are identified : 1) open-system freezing and 2) semi-closed system (or closed system) freezing
The first record of stable isotopes through a complete sequence of ice within an open-system pingo in northwestern Mongolia indicates a complex history of ice formation and pingo growth. A continuous section of ice 32 m long was cored through
B.P.) and a second at late Pleistocene-early Holocene time. These two periods reflect rather a humid phase, separated by an arid phase during peak glaciation.
Australia ; Carrying capacity ; Drainage network ; Grain size distribution ; Isotope analysis ; New South Wales ; Sediment budget ; Soil erosion ; Tracer ; Watershed
This paper demonstrates the use of radium-isotope ratios to trace sediment in a catchment with a uniform granite lithology. Radionuclide concentrations in transported sediment are measured spatially and temporally, and the likely effects of particle
size and density separation during transport are examined. Using this technique, the AA. are able to identify the source of coarse-grained (bed-load) sediment deposited in the drainage network of a catchment subjected to logging. The AA. consider
C 14 dating ; Carbonate rock ; Fault ; Geochemistry ; Geochronology ; Isotope dating ; Limestone ; Nevada ; United States of America ; Utah
The AA. report a rate of production for 14CO in calcite. They use cryogenic methods to separate in situ cosmogenic 14CO from in situ cosmogenic 14CO2, or from biological 14C present as organic matter or as CaCO3. With the rate of production
L'analyse isotopique de 36 échantillons d'eau du sol est faite dans le cadre d'une étude hydrogéologique en Tripolitaine. La mesure des isotopes stables H/H, O/O et C/C et les isotopes radioactifs H/'H et C/C reflètent les mélanges verticaux et
Sedimentologic and stable isotopic studies in the Çal basin-fill provide new insights on the late Neogene–Quaternary climatic pattern in the eastern Mediterranean. An erosional unconformity separates the Pleistocene siliciclastic and calcrete
deposits above as a single sedimentary unit resting on top of floodplain fines and restricted to the basin center. The stable isotopic analysis of the palustrine carbonates and pedogenic calcretes displays a wide range of values and the lack of significant
of the sources of water and solutes agrees with conclusions from attempts at hydrograph separation, that mixing of water reservoirs of fixed solute composition cannot be used for quantitative descriptions of the system. Estimated annual solute yields are high
Initial interpretation of the sediments from the Burmester core indicated that 17 deep-lake cycles, separated by shallow-lake and soil-forming intervals, occurred in the Bonneville basin during Brunhes Chron (the last 780 000 yr). The re-examination
of the core, with new sedimentological, geochronological, and paleontological data, indicate that only 4 deep-lake cycles occurred during this period, apparently correlative with marine oxygen-isotope stages 2, 6, 12, and 16. This interpretation suggests
separate phases of accumulation of fine-grained lake deposits, which are correlated with the late High Glacial (Marine Isotope Stage 2), the Middle Würmian (MIS 3) and the pre-Würmian. The Middle Würmian sediments are of particular stratigraphic importance
Eight box cores from the tropical Atlantic were studied in detail with regard to foraminiferal oxygen isotopes, radiocarbon, and Globorotalia menardii abundance. A standard Atlantic oxygenisotope signal was reconstructed for the last 20.000 yr
. It is quite similar to the west-equatorial Pacific signal published previously. Deglaciation is seen to occur in two steps which are separated by a pause. Onset of deglaciation is after 15.000 yr B.P. The pause is centered between 11.000 and 12.000 yr B.P
This paper proposes, as a testable hypothesis, a basin-scale approach for interpreting the abundance of in situ produced cosmogenic isotopes, an approach which considers explicitly both the isotope and sediment flux through a drainage basin
. This model is designed for interpreting isotope abundance in sediment. The AA. suggest that measured isotope abundances may reflect spatially averaged rates of erosion if a basin is in isotopic steady state and if sampled sediments are well mixed.
Isotopic approach to soil carbonate dynamics and implications for paleoclimatic interpretations
Carbon ; Carbonate ; Geochemistry ; Holocene ; Isotope analysis ; Nevada ; Oxygen 18 ; Palaeoclimatology ; Semi-arid area ; Soil ; United States
The AA. examine stable and radiogenic isotopes of C and stable isotopes of O in carbonate sampled from gravel coatings and soil matrix in three Holocene soils from a semiarid region in Nevada. By comparing isotopic measurements with modeled stable
isotope profiles and radiocarbon ages, the AA. assess the nature of soil carbonate with respect to its origin (detrital, dust, or pedogenic) and dynamic nature (closed or open to atmospheric CO2) over time.
Monthly precipitation samples were collected at Tsukuba City from 1992 to 2006, and isotope ratios of oxygen and hydrogen were analyzed for all samples. The isotope ratios of monthly precipitation have no remarkable trend in their seasonal change
. The temperature effect on isotopes in precipitation is found durinf cool period. In cases of snowfall, precipitation from Baiu front and autumnal rain front, the isotope ratios in precipitation are relatively lighter than those of other cases.
The Greenland Ice Sheet Project 2 (GISP2) oxygen isotope record, with its high-resolution detail, yields crucial information on past climate change. Here the AA. present high-resolution GISP2 oxygen isotope records and mention some of their climatic
implications, with emphasis on the abrupt switches in isotope ratios in the Northern Hemisphere.
Isotope und ihre Anwendung in den Geowissenschaften, in der Bergbausicherheit und im Umweltschutz.. (Isotopes and their application in the geological sciences, the safety in mining and protection against environmental pollution)
Congrès ; Extraction minière ; Généralités sur la géographie ; Géochimie ; Isotope ; Lutte contre la pollution ; Mine ; Pollution ; Sciences de la Terre ; Sécurité
Geomorphological applications of cosmogenic isotope analysis
Bibliography ; Dating ; Erosion rate ; Geochemistry ; Geomorphology ; Isotope analysis ; Mass movement ; Weathering
The AA. focus on the geomorphological applications of in situ-produced cosmogenic isotope analysis. The past decade has seen a rapid growth in applications of cosmogenic isotope analysis to a wide range of geomorphological problems
Climate in southwestern Ontario, Canada, between AD 1610 and 1885 inferred from oxygen and hydrogen isotopic measurements of wood cellulose from trees in different hydrologic settings
Oxygen and hydrogen isotopes were measured in wood celullose and cellulose-nitrate from trees that grew in different hydrologic settings in southwestern Ontario. An isotope model that accounts for isotopic fractionations associated
with photosynthesis in plants was applied to the stable isotope data to infer past meteoric water isotopic composition and seasonal air moisture variations. The result is an account of summer and winter conditions in southwestern Ontario for 275 yyears (1610 to 1885
Sr-isotope record of Quaternary marine terraces on the California coast and off Hawaii
California ; Etats-Unis ; Géochimie ; Hawaii ; Isotope ; Niveau marin ; Paléo-environnement ; Quaternaire marin ; Stratigraphie ; Terrasse marine
California ; Geochemistry ; Hawaii ; Isotope ; Marine quaternary ; Marine terrace ; Paleo-environment ; Sea level ; Stratigraphy ; United States
The AA. use Sr-isotope stratigraphy to constrain relative and absolute ages of Quaternary marine terraces formed during interglacial periods in southern California. They test for the presence of a glacial-interglacial oscillatory signal superimposed
on the longer-term Sr-isotope trend for the Quaternary.
Oxygen isotope constraints on surface ocean temperatures
Donnée substitutive ; Foraminifère ; Géographie physique ; Isotopes de l'oxygène ; Paléoclimatologie ; Quaternaire zone chaude ; Température de surface de l'océan
Published oxygen isotope results from benthic and planktonic foraminifera are used to constrain the extent to which surface ocean temperatures in the tropics changed between glacial and inter-glacial time. The possible impacts of bioturbation
and of the redistribution of oxygen isotopic ratios within the sea, putting aside the oxygen isotope results, are consistent with the CLIMAP project conclusion that tropical ocean temperatures remained within ca. 2oC of their present value.