Atmospheric circulation ; Biogeography ; Carbon cycle ; Carbon dioxide ; Climatic cooling ; Glacial features ; Holocene ; Interglacial ; Model ; Palaeoclimatology ; Peat bog
This paper focuses on the role of carbon accumulation in peatlands in lowering the concentration of CO2 in the atmosphere. The objective is to determine whether carbon models and proxy data for atmospheric CO2 are consistent with the hypothesis
that carbon accumulation in peatlands lowers atmospheric CO2, thus playing an important role in ice-age initiation.
Archaeology ; Biogenic process ; C 14 dating ; Carbonate ; Dating ; Fruit ; Microstructure ; Quaternary
The AA. present an extended set of C 14 dates on the carbonate fraction of Lithospermum fruits from 4 modern and 11 fossil samples. The data suggest that biogenic carbonate from the fruits of Lithospermum represents suitable material for radiocarbon
dating. Biogenic carbonate of Lithospermum fruits, like that of Celtis, represents a new source of chronological information for late Quaternary studies.
Nécessité d'une analyse des causes des changements climatiques dans le contexte d'une interactivité de toutes les composantes du système climatique (incluant la biosphère et le cycle du carbone) et de la dynamique du développement socio-économique.
Factors affecting 14C ages of lacustrine carbonates : timing and duration of the Last Highstand Lake in the Lahontan Basin
California ; Carbonate ; Datation C 14 ; Etats-Unis ; Géochimie ; Lac ; Nevada ; Niveau lacustre ; Paléogéographie
C14 dating ; California ; Carbonate ; Geochemistry ; Lake ; Lake level ; Nevada ; Palaeogeography ; United States
The purposes of this paper are to determine when corrections for low initial 14C/c ratios in lake water should be made and which Lahontan carbonates listed in published carbonate 14C data bases (e.g., Benson, 1978, 1981; Benson et al., 1991) have
remained closed systems with respect to the isotopes of carbon. Based on these determinations, the most reliable of the carbonate 14C ages are used to calculate carbonate accumulation rates. The accumulation rates then are applied to the measured thickness
of highstand carbonates and used to estimate the timing and duration of the last Lake Lahontan highstand.
Atmosphère ; Biogéochimie ; Cycle du carbone ; Géochimie ; Matière organique ; Tourbière ; Variation climatique ; Zone froide
Atmosphere ; Biogeochemistry ; Carbon cycle ; Climatic variation ; Cold area ; Geochemistry ; Organic materials ; Peat bog
The purpose of this paper is to discuss the processes involved in the exchange of carbon between the atmosphere and the organic deposits in peatlands. Particularly, the possible changes in the past in comparison with present-day conditions
Asie ; Dioxyde de carbone ; Dissolution karstique ; Haute montagne ; Karst ; Montagne ; Roche carbonatée ; Tibet
Asia ; Carbon dioxide ; Carbonate dissolution ; Carbonate rock ; High mountain ; Karst ; Mountain ; Tibet
Tibet between 4000 and 5000 m a.s.l. has the highest known currently developing karst features. Measurements taken of carbon dioxide pressure (one of the lowest in the world), solubility of Tibetan limestones, and electrical conductivity of karst
L'objet de cette revue est de présenter la recherche actuelle concernant les facteurs qui influencent la dynamique du carbone dans les forêts tropicales humides : mesures de terrain, écophysiologie, modélisation, télédétection.
Carbon ; Carbon 13 ; 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.
The carbon pools of biomass, littering, and SOC were studied with regards to carbon cycles in epikarst zone, taking an example of Yaji Karst Experiment Site in Guilin. This study was focused on SOC and its lability, SOC decomposition rate, CO2
regime in the soils. This study was to elucidate the capacity of soil carbon driving for the epi-karstification and the significance of carbon transfer in carbon cycles of karst system.
A brief introduction to recent applications of several sediment-analysis techniques in palaeolimnological studies - dry bulk density and water content, mineral magnetism, carbonate content, and content of total organic carbon, nitrogen content
and carbon/nitrogen ratio
Determination of dry bulk density and water content, mineral magnetism, carbonate content, total organic carbon (TOC) content, nitrogen content (N%) and carbon/nitrogen (C/N) ratio are among those techniques which have been widely applied
Carbon's calculatory spaces : the emergence of carbon offsets in Costa Rica
Compensation de carbone ; Costa Rica ; Cycle du carbone ; Forêt ; Production de l'espace ; Reboisement ; Rôle de l'Etat ; Territorialité
Carbon cycle ; Carbon offset ; Costa Rica ; Forest ; Production of space ; Reforestation ; Role of the State ; Territoriality
L'A. étudie les pratiques comptables nécessitées pour créer des compensations de carbone par le reboisement au Costa Rica, en insistant sur les espaces qui sont produits par ces pratiques. Cette compensation peut être considérée comme une
Performing carbon’s materiality : the production of carbon offsets and the framing of exchange
Carte ; Compensation de carbone ; Costa Rica ; Economie du carbone ; Economie rurale ; Marchandisation ; Matérialité ; Performance économique ; Système d'information géographique
Carbon economy ; Carbon offset ; Commodification ; Costa Rica ; Geographical information system ; Map ; Rural economy
L’A. analyse la mise en place d’une compensation carbone forestière au Costa Rica. Il explique le rôle de chacun des acteurs du projet (l’Etat, les scientifiques et les propriétaires terriens) dans la prise de mesures de la zone concernée au travers
The comparative role of key environmental factors in determining savanna productivity and carbon fluxes : a review with spatial reference to northern Australia
Australia ; Carbon cycle ; Carbon dioxide ; Climatic change ; Ecosystem ; Fire ; Northern Territory ; Precipitation ; Productivity ; Radiation ; Savanna ; Temperature
For savannas, the key environmental drivers controlling vegetation productivity are water and nutrient availability, vapour pressure deficit (VPD), solar radiation and fire. Changes in these environmental factors can modify the carbon balance
of these ecosystems. Here the AA. have reviewed the various environmental controls on the spatial and temporal patterns on savanna carbon fluxes in northern Australia. Such studies are critical in predicting the impacts of future climate change on savanna productivity
regulated western Canadian peatland initiation. Peatlands, the largest terrestrial carbon pool, and their carbon-budgets are sensitive to hydrological fluctuations. The AA. demonstrate that global carbon-budgets are sensitive to small climatic fluctuations
; thus international agrrements on greenhouse gasses need to take into account the natural carbon-budget imbalance of regions with large climatically sensitive carbon pools.
A simple linear response model describing the functional relationship between ocean carbon cycle parameters and paleoclimate tracers (atmospheric pCO2, δ13C, CaCO3 saturation) was derived from a set of sensitivity experiments performed previously
using a three-dimensional carbon cycle model. The linear model is optimally fitted to ice and marine sediment core records for the last 120,000 yr to estimate the carbon cycle parameter changes that could have caused the observed reduction of atmospheric
Records of climatic changes in the carbonate profiles of Russian Chernozems
Analyse isotopique ; Carbonate ; Carbone ; Caucase ; Chernozem ; Holocène ; Humidité du sol ; Irrigation ; Paléo-environnement ; Propriétés du sol ; Quaternaire ; Russie d'Europe ; Sol ; Variation climatique
Carbon ; Carbonate ; Caucasus ; Chernozem ; Climatic variation ; European part of Russia ; Holocene ; Irrigation ; Isotope analysis ; Palaeo-environment ; Quaternary ; Soil ; Soil moisture ; Soil properties
The carbonate profiles of Chernozems bear important information on soil processes and can be successfully used for paleoenvironmental reconstruction. In the Northern Caucasus region, carbonate profiles of Chernozems were compared under anthropogenic
of the Holocene from changes in carbonate profiles of a soil chronosequence.
Bashkortostan ; Carbon cycle ; Carbon dioxide ; Ecosystem ; European part of Russia ; Evapotranspiration ; Fuel ; Oil ; Organic materials ; Phytomass
Principales caractéristiques des composantes du bilan du carbone lié à la phytomasse. Masse de carbone organique de la couverture du sol. Emission de carbone due à la respiration des sols et à la comobustion des combustibles fossiles.
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