Atmospheric carbon dioxide and radiocarbon in the natural carbon cycle. I. Quantitative deductions from records at Mauna Loa Observatory and at the South Pole
- eds.
From carbon and the biosphere conference; Upton, New York, USA (16 May l972). ln carbon and the biosphere. The concentration of atmospheric CO/sub 2/ in the Northern Hemisphere increased by 6.8 ppM from 1959 to 1969, according to a long series of measurements at the Mauna Loa Observatory, Hawaii. In the same period the Southern Hemisphere concentration increased by 6.7 ppM, according to an even longer series of measurements of South Polar air. These increases, when averaged, correspond to 2.34% of the presumed preindustrial CO/sub 2/ concentration of 290 ppM and imply that approximately 49% of the contemporary production of CO/sub 2/ from combustion of fossil fuel and kilning of limestone remained airborne. The approximately 51% not remaining airborne was evidently incorporated into the oceans and land biota. To learn more about this uptake, we have taken into account atmospheric radiocarbon (/sup 14/C) variations as recorded in tree rings, and to interpret this record we have examined a series of geochemical models of the reservoirs into which CO/sub 2/ and /sup 14/C can mix. The essential character of these models was established by evaluating an analytically derived atmospheric transfer function for a wide range of linear- model parameters. For a purely oscillatory /sup 14/C source, this function gives the attenuation and phase shift of /sup 14/CO/sub 2/ in the lower atmosphere; for a purely exponentially increasing CO/sub 2/ source, it gives the fraction of CO/ sub 2/ remaining airborne or in the lower atmosphere. In both cases the source is assumed to have operated until initial transient variations have died out. For reasonable reservoir sizes and transfer times, the stratospheric (heliomagnetic) variation in /sup 14/CO/sub 2/, as estimnted from direct observations of cosmic rays and sunspot numbers, is strongly attenuated in the lower atmosphere, whereas the predicted airborne fraction agrees with the earlier implied value of 49% (42% for the lower atmosphere) only if the carbon pool of the land biota grows appreciably. These models, with nonlinear corrections, arc used to predict year-by-year simultaneous variations in atmospheric CO/sub 2/ and /sup 14/CO/sub 2/. (auth)
- Research Organization:
- Univ. of California, San Diego, La Jolla; Brookhaven National Lab., Upton, N.Y. (USA)
- NSA Number:
- NSA-29-012754
- OSTI ID:
- 4368683
- Report Number(s):
- CONF-720510-
- Resource Relation:
- Conference: Carbon and the biosphere conference, Upton, New York, USA, 16 May 1972; Other Information: Orig. Receipt Date: 30-JUN-74; Related Information: Carbon and the biosphere
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
*CARBON 14- ABUNDANCE
*CARBON DIOXIDE- ABUNDANCE
AIR POLLUTION
BIOSPHERE
EARTH ATMOSPHERE
FOSSIL FUELS
FOSSIL-FUEL POWER PLANTS
GASEOUS WASTES
MATHEMATICAL MODELS
MEASURING METHODS
METABOLISM
QUANTITY RATIO
SEAS
TRACER TECHNIQUES
TREES
UPTAKE ABUNDANCE