Groundwater isotopic evidence for paleorecharge in U.S. High Plains aquifers
Aquifer ; Deuterium ; Great Basin ; Groundwater ; Isotope analysis ; Oxygen 18 ; Palaeohydrology ; Tritium ; United States of America
This study interprets relative groundwater ages, distinguishes vertical and lateral flow paths, and evaluates paleoclimatic implications of isotopic stratification of groundwater beneath the U.S. High Plains.
Ross ice shelf oxygen isotopes and West Antarctic climate history
Antarctique ; Barrière de Ross ; Carotte de glace ; Glace ; Géographie des régions polaires ; Isotopes de l'oxygène ; Paléoclimatologie ; Quaternaire supérieur ; Ross Ice Shelf
The Ross Ice Shelf oxygen isotopic profile at station J-9 covers at least the last 30,000 yr.
This paper discusses the chemical evolution and the recharge elevation of spring water by using major dissolved components and isotopic composition around Asama volcano. In addition the A. will provide the conceptual model of groundwater flow system
The development of biogeography as a science has involved the assimilation of both new concepts and new techniques. Stable isotopes have been used in the study of climatic history, the evolution of the biosphere, the biogechemical cycling
Fractionation mechanism of stable isotope in evaporating water body
China ; Evaporation ; Isotope analysis ; Lake ; Moisture ; Simulation ; Temperature ; Tibet ; Water cycle
This study quantificationally analyses the interaction between evaporating water body and atmosphere, and the influences of different factors on the evaporation by probing into the fractionation mechanism of stable isotope as water body is vaporized
A review of various factors influencing the stable carbon isotope ratio of organic lake sediments by the change from glacial to post-glacial environmental conditions
The AA. present the preliminary results of measurements of diurnal changes in the isotopic composition of atmospheric CO2 in Kraków. They present four experiments done in different seasons of the year. Results show that the isotope composition
This paper assesses the preservation of biogenic isotopic composition of the collagen fraction of mammal bone and tooth from the uppermost well-defined layer of the cave (numbered 1A) and determines the ecological basis for interspecific differences
in the carbon and nitrogen isotopic compositions of mammals from other late Pleistocene sites in Eurasia.
Chronology and paleohydrology of Late Quaternary high lake levels in the Manyara Basin (Tanzania) from isotopic data (18O, 13C, 14C, Th/U) on fossil stromatolites
Dating ; Isotope ; Lake level ; Palaeogeography ; Palaeohydrology ; Quaternary ; Tanzania
In this article, new isotopic data on the hydrology and paleohydrology of the Lake Manyara basin are presented. They complement previous studies on lakes Natron and Magadi, to the north, and provide additional information on late Pleistocene
The AA. examine evidence for climatic change at the Aubrey Clovis site, north-central Texas, over the past 14,000 yr. The primary emphasis of this paper will be on stable isotopic evidence from pedogenic and lacustrine carbonates from the study site
. An indepedently derived alluvial history from the same locality corroborate the isotopic data.
Structure and timing of the last deglaciation : oxygen-isotope evidence
Foraminiferal oxygen-isotope data from 24 Tropical Atlantic sediment cores, constrained by 77 14 C dates, are stacked to form a composite record of isotopic Termination 1. This record indicates that most of the isotopic transition at the end
Carbon isotopic changes in benthic foraminifera from the western South Atlantic: reconstruction of glacial abyssal circulation patterns
Analyse isotopique ; Atlantique ; Atlantique Sud ; Circulation abyssale ; Foraminifère benthique ; Géographie physique ; Isotope O18-O16 ; Isotopes du carbone ; Océan ; Paléohydrologie ; Pléistocène supérieur ; Quaternaire marin ; Rio Grande ; Vema
Oxygen-and carbon-isotopic analyses have been performed on the benthic foraminifer Planulina wuellerstorfi in seven Late Quaternary cores from the Vema ChannelRio Grande Rise region.
An isotopic study of paleosol carbonates from Olduvai gorge
The isotopic composition (oxygen and carbon isotopes) of paleosol carbonates is used to give estimates of the paleoclimatic history of East Africa during the Plio-Pleistocene. Three major periods of climatic change in this terrestrial setting
occurred at about 1.67, 1.3 and 0.6 myr. These involved major changes in flora as well as major changes in the isotopic composition of meteoric water. Overall, the climate has become warmer and more arid over the part 2.2 myr.
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.
Messungen des Gehalts an stabilen Isotopen in einer temperierten randalpinen Schneedecke Measurements of the content of stabil isotopes in a temperated cover on border areas of the Alpes
During the ablation period of 1974, the content of deuterium and oxygen-18 in snow was measured, sampled at the layers of an open area lysimeter snow cover at 1030 m a.s.l. Changes in isotope concentrations are subject to the influence of melt
-and rainwater percolation through the snow cover, but also to evaporation and condensation processes. Abrupt, short-termed alterations of isotopic contents are discussed as well as the isotopic balance and deuterium-oxygen-18 relations. (HSC).
A detailed 31,000-year record of climate and vegetation change, from the isotope geochemistry of two New Zealand speleothems
Carbon ; Cave ; Glaciation ; Isotope analysis ; New Zealand ; Oxygen 18 ; Palaeo-environment ; Palaeobotany ; Palaeoclimate ; Pleistocene ; Quaternary ; South Island
This paper presents continuous high-resolution stable isotope records of environmental change in New Zealand from speleothems that grew over the last 31,000 yr. Oxygen isotope variation in these speleothems primarily represents changes
in the meteoric waters falling above the caves, possibly responding to latitudinal changes in the position of the Subtropical Front in the Tasman sea. Carbone isotope variations in the speleothems record changes in forest productivity, closely matching existing