Vegetation effects on the isotope composition of oxygen in atmospheric CO2

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.