Vegetation effects on the isotope composition of oxygen in atmospheric CO2
Article Abstract:
The carbon dioxide (CO2) exchange with the terrestial biosphere reveals that the significance of the oceans and individual terrestrial biomes as net sinks for anthropogenic CO2 depends on the isotopic ration of CO2 in the atmosphere. The differential diffusion of C-18 O-16 and C-16 O-2 and isotopic effects in oxygen exchange with chloroplast water results in fractionation of the oxygen isotopes of CO2 occurring in plants. O-18 and its precipitation is depleted when it occurs near 70 degree N, and atmospheric CO2 of O-18 is depleted due to photosynthesis and respiration, explaining the depletion of O-18 in atmospheric CO2 at high northern latitudes.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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C-quest in the Amazon Basin: Whether Amazonia is a carbon-dioxide source or sink has a significant effect on estimates of the global carbon budget
Article Abstract:
Seven pete (10(super15)) grams of carbon are emitted each year through fossil-fuel burning, with a further 1-2 Pg through forest clearance. Interest has focused on the Amazon Basin and flux measurements confirm that it experiences substantial carbon uptake. Carbon flux measurements are difficult to make and there are too few of them. Tian and colleagues have developed a model based on month-by-month climate observations, interpolated to a basin-wide grid. Terrestrial biogeochemical models can explain variations in atmospheric CO(sub2) concentrations through the effects of El Nino on tropical forests.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
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Fluxes of CO2 and water between terrestrial vegetation and the atmosphere estimated from isotope measurements
Article Abstract:
Net CO2 exchange between terrestrial vegetation and the atmosphere is the sum of two fluxes, uptake by gross primary productivity and release by respiration. Small vertical gradients in 13C and 18O in atmospheric CO2 above vegetation can be used to estimate the two components separately at the local scale. Evapotranspiration rates can be determined by analyzing the 18O content of moisture in air samples.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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