Studies of artificial carbon-14 in the carbon cycle

Ergin, Mehmet (1970) Studies of artificial carbon-14 in the carbon cycle. PhD thesis, University of Glasgow.

Abstract

The basic assumption of the radiocarbon dating method is that the carbon-14 concentrations in the atmosphere have remained essentially constant in the past although there is some evidence that fluctuations have occurred during the past 10 millennia# These fluctuations are reflected in biospheric and oceanic carbon-14 concentrations since the distribution of carbon-14 is controlled by the exchange processes between the respective reservoirs. A precise knowledge of these exchange rates is desirable, therefore, if past carbon-14 fluctuations are to be explained and future carbon-14 concentrations predicted. Evaluation of these parameters also yields important data for the study and understanding of meteorological, biological and oceanographic processes. Some estimates of exchange rates have been made on the basis of measured carbon-14 variations during the past 20 years as a result of the Suess effect. Further studies have been based on the artificial carbon-14 produced prior to the major test series of 1961-62. During 1961-62 large-scale atmospheric testing of thermonuclear devices produced substantial quantities of carbon-14 through the interaction of escaping neutrons from the weapons with atmospheric nitrogen, 14N (n1H) 14C. Prior to 1961 the amount of carbon-14 produced by nuclear weapons amounted toonly about one third that produced in the new test series. Thus the most recent amounts produced can be regarded as a new tracer for the study of the distribution and exchange rates of carbon dioxide between the various dynamic carbon reservoirs, i. e., the troposphere) stratosphere) ocean surface layer, deep ocean and biosphere. During 1967 and 1968 extensive measurements were madeof the carbon-14 concentrations in tropospheric carbon dioxide samples collected at a world-wide network of sampling stations. These results) together with the stratospheric and oceanic data have been used to calculate the inventories of artificial carbon-14 in various reservoirs of the carbon cycle for July 1967 and 1968. Residence times of carbon dioxide in various reservoirs of the carbon cycle have also been studied using a number of "chain" and "cyclic" models of varying complexity. The calculated exchange rate parameters indicate that both the ocean and biosphere are important in determining the atmospheric carbon-14 level. The magnitude of the exchange processes between the atmosphere and each of these reservoirs are comparable. However, the relatively large size of the oceanic reservoir suggests that this is the major controlling factor over the long term.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Colleges/Schools: College of Science and Engineering
• Supervisor's Name: Supervisor, not known
• Date of Award: 1970
• Depositing User: Mrs Marie Cairney
• Unique ID: glathesis:1970-74382
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 04 Sep 2019 16:06
• Last Modified: 04 Sep 2019 16:09
• URI: https://theses.gla.ac.uk/id/eprint/74382