Declining trend in the C 13/C 12 ratio of atmospheric carbon dioxide from tree rings of South African Widdringtonia cedarbergensis
Action anthropique ; Afrique du Sud ; Analyse isotopique ; Cape Province ; Carbone ; Dendroclimatologie ; Dendrologie ; Géochimie ; Géochronologie ; Paléoclimat ; Précipitation
Cape Province ; Carbon ; Dendroclimatology ; Dendrology ; Geochemistry ; Geochronology ; Human impact ; Isotope analysis ; Palaeoclimate ; Precipitation ; South Africa
This paper reports the first high-resolution (annual) C 13/C 12 chronology for both Africa and the Southern Hemisphere. The 77-yr stable carbon isotope chronology was developed from 6 Widdringtonia cedarbergensis trees from a site in the Cedarberg
Mountains, Western Cape Province, South Africa. The results indicate that C 13/C 12 ratios are not different from 1900 to 1949. After 1949, however, values become significantly more negative to 1977. This decline can be related to the anthropogenic impact
Carbon ; Carbon13 ; Carbon dioxide ; Chemical erosion ; Geochemistry ; Isotope analysis ; Lesser Antilles ; Stream ; Tracer ; Underground water ; Volcanic rock ; Weathering ; West Indies
The AA. use carbon isotopes in the dissolved load of rivers from the Lesser Antilles volcanic arc (Guadeloupe, Martinique and Dominica islands) to constrain the source of the carbon dioxide (CO2) involved in the neutralization reactions during water
weathering is an additional parameter that could explain the high weathering rates of volcanic rocks. The study also shows that a significant part of the carbon degassed from the Earth's interior is not released as CO2 to the atmosphere, but as DIC(dissolved
inorganic carbon)to the ocean because it interacts with the groundwater system. This study calls for a better understanding of the contributions of deep carbon to the hydrosphere and its influence on the development of the Critical Zone.
In this study, four wetland sites and one degraded wetland site in the Zoigê alpine wetland, located at the Qinghai-Tibet Plateau, were selected to investigate the relationships of stable isotope and labile organic carbon dynamics with groundwater
elevation or water table level. The AA.also examine if the δ13C abundance, soil water soluble organic carbon (WSOC), light fraction organic carbon (LFOC), can be used as potential indicators of soil organic carbon (SOC) dynamics in these wetland sites
Amino acid, organic nitrogen, and stable carbon isotope (C 13/C 12) profiles through a core from East Taihu Lake are interpreted in terms of paleoecology and paleoclimate over the last 15,000 yr. The average δ C 13 values from a core from West Taihu
Lake are evidently higher than values from East Taihu Lake, showing that East Taihu Lake sediments are related to heterotrophic carbon sources from the watershed. The western part of Taihu Lake, by contrast, has been a lacustrine environment since
Factors controlling carbonate dissolution rates quantified in a field test in the Austrian alps
Alpes ; Autriche ; Bassin-versant ; Bilan de masse ; Carbonate ; Dissolution karstique ; Expérimentation de terrain ; Géochimie ; Karst ; Lithologie
Alps (The) ; Austria ; Carbonate ; Carbonate dissolution ; Field experiment ; Geochemistry ; Glacier mass balance ; Karst ; Lithology ; Watershed
data, and limestone pedestals. For the field test, 70 carbonate tablets were exposed to natural dissolution for 1 year, over 13 sites on the north slope of the Hochschwab Massif in the Austrian Alps. The influences of altitude, subsoil vs. sub-aerial
The aims of this study were to investigate the factors controlling carbonate dissolution within one restricted area, the carchment area of a major alpine karst spring, by comparing the results from carbonate tables, mass-balance from hydrological
Holocene landscape history and palaeohydrology evidenced by stable carbon isotope (δ C 13)analysis of alluvial sediments in the Mbari valley (5°N/23°E), Central African Republic
an important role on the runoff processes and on the discharge of the draining river systems. Therefore, this study focuses on the examination of alluvial soils and the determination of stable carbon isotopes of organic sediments on the Mbomou plateau
The purpose of this work is to explore the possibility of using the stable isotopic composition of carbon in phytoliths to reconstruct aspects of paleoenvironmental conditions. The basis for this approach is related to the influence of climate
It appears that in the sparsely vegetated Mojave Desert, the C13/C12 of pedogenic carbonate is controlled by differences in plant density and biological activity. This relationship may provide a tool for assessing past vegetational densities
Par l'étude des rapports isotopiques O18/O16 et C13/C12, des pourcentages et des vitesses d'accumulation des carbonates et des matériaux éoliens, établissement d'une chronologie des événements paléoclimatiques pour les 950 000 dernières années.
Oxygen-18, deuterium and carbon-13 content of organic matter from litter and humus layers in podzolic soils
tendent à montrer que la relation qui existe entre la composition isotopique de la cellulose et certains paramètres du milieu n'est pas masquée par le début de décomposition subie par la litière dans le sol. Les teneurs en carbone13 sont indépendantes.
A l'aide des données isotopiques (oxygène 18 et carbone13), de l'étude des changements de forme des coquilles de Melanopsis et de la disparition soudaine de Viviparus, reconstitution des plus importants cycles climatiques du Pléistocène.
The implications for paleodietary and paleoclimatic reconstructions of intrapopulation variability in the oxygen and carbon isotopes of teeth from modern feral horses
Carbon ; Horse ; Isotope analysis ; North Carolina ; Oxygen 18 ; Palaeo-ecology ; Palaeo-environment ; Quaternary ; Temperate zone ; United States of America
The AA. analyze tooth enamel from feral horses from a temperate climate : Shackleford Banks, North Carolina (USA). Enamel δC 13 values are compared with the values of local plants. Enamel δO 18 values are compared with values of surface water
samples and with analyses of the δO 18 values of precipitation at nearby Hatteras, North Carolina. The variability of both δO 18 and the δC 13 values among individuals within this population demonstrates that horses from relatively homogenous temperate
Palustrine carbonates and pedogenic calcretes in the Çal basin of SW Anatolia : Implications for the Plio-Pleistocene regional climatic pattern in the eastern Mediterranean
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
δ18 O-δ13 C may indicate subhumid conditions or significant diagenetic alteration. The δ13 C values of these carbonates, organic δ13 C data from calcretes and floral remains indicate that the landscapes were dominated by C3 forest plants.
Modélisation numérique des changements globaux. Bilans du 71e congrès annuel de la Société américaine de météorologie, Nouvelle-Orléans, 13-18 janvier 1991)
Effect of cactus pear cultivation after Mediterranean maquis on soil carbon stock, δ13C spatial distribution and root turnover
Carbone ; Carbone13 ; Domaine méditerranéen ; Ecosystème ; Italie ; Maquis ; Matière organique ; Propriétés du sol ; Sicilia ; Sol cultivé ; Utilisation du sol ; Verger
Carbon ; Carbon13 ; Cultivated land ; Ecosystem ; Italy ; Land use ; Mediterranean area ; Mediterranean scrub vegetation ; Orchard ; Organic materials ; Sicilia ; Soil properties
The aim of this work was to investigate the effect of land use change from maquis to agriculture on soil organic carbon (SOC) stock and its spatial distribution in a Mediterranean system. Three Mediterranean land use systems (seminatural vegetation