After 1750 and the onset of the industrial revolution, the anthropogenic fossil component and the non-fossil component in the total atmospheric CO 2 concentration, C(t), began to increase. Despite the lack of knowledge of these two components, claims that all or most of the increase in C(t) since 1800 has been due to the anthropogenic fossil component have continued since they began in 1960 with "Keeling Curve: Increase in CO 2 from burning fossil fuel." Data and plots of annual anthropogenic fossil CO 2 emissions and concentrations, C(t), published by the Energy Information Administration, are expanded in this paper. Additions include annual mean values in 1750 through 2018 of the 14 C specific activity, concentrations of the two components, and their changes from values in 1750. The specific activity of 14 C in the atmosphere gets reduced by a dilution effect when fossil CO 2 , which is devoid of 14 C, enters the atmosphere. We have used the results of this effect to quantify the two components. All results covering the period from 1750 through 2018 are listed in a table and plotted in figures.These results negate claims that the increase in C(t) since 1800 has been dominated by the increase of the anthropogenic fossil component. We determined that in 2018, atmospheric anthropogenic fossil CO 2 represented 23% of the total emissions since 1750 with the remaining 77% in the exchange reservoirs. Our results show that the percentage of the total CO 2 due to the use of fossil fuels from 1750 to 2018 increased from 0% in 1750 to 12% in 2018, much too low to be the cause of global warming.
The classic problem of alpha absorption is discussed in terms of the quantitative determination of the activity of "weightless" alpha sources and the specific alpha activity of extended sources accounting for absorption in the source medium and the window of a large area ZnS(Ag) scintillation detector. The relationship for the expected counting rate gamma of a monoenergetic source of active area A, specific alpha activity C, and thickness H that exceeds the effective mass density range Rs of the alpha particle in the source medium can be expressed by a quadratic equation in the window thickness x when this source is placed in direct contact with the window of the ZnS(Ag) detector. This expression also gives the expected counting rate of a finite detector of sensitive area A exposed to an infinite homogeneous source medium. Counting rates y obtained for a source separated from a ZnS(Ag) detector by different thicknesses x of window material can be used to estimate parameter values in the quadratic equation, y = a + bx + cx2. The experimental value determined for the coefficient b provides a direct estimation of the specific activity C. This coefficient, which depends on the ratio of the ranges in the source medium and detector window and not the ranges themselves, is essentially independent of the energy of the alpha particle. Although certain experimental precautions must be taken, this method for estimating the specific activity C is essentially an absolute method that does not require the use of standards, special calibrations, or complicated radiochemical procedures. Applications include the quantitative determination of Rn and progeny in air, water, and charcoal, and the measurement of the alpha activity in soil and on air filter samples.
A dosimetric model is proposed for the gastrointestinal tract based upon the physiological model of EVE (1966a). A general equation describing the kinetics of linear first order phenomena is applied to obtain the burden of radionuclides or disintegrations in the contents of the various segments of the GI tract. The model gives equations for the calculation of the "dosimetric" average dose equivalent and dose equivalent rate to an entire segment as well as instantaneous values at any location within a given segment as applicable to single or continuous uptakes of parent and daughter radionuclides. Allowance is made for both the absorption of radionuclides as well as mass from the contents of all segments; although, this is not always considered significant. The model permits the determination of the quantities of a radionuclide absorbed into the blood, the ratio of daughter to parent disintegrations and the maximum to average dose equivalent rate in a particular segment of the GI tract. Numerical examples are given for various intakes. Maximum permissible daily ingestion rates of fictitious single soluble and insoluble radionuclides with an effective energy term of unity in all segments are given over a large range of half-lives and are compared to values calculated on the basis of current ICRP recommendations. It is proposed that ratios of the maximum to dosimetric average dose equivalent rate be used to define a distribution factor to take into account relatively high dose rates at particular locations within a segment of the GI tract.All equations have been derived using the more fundamental units of atoms or disintegrations and disintegration rates rather than the more popular pCi and pCi-day units. The former units are more fundamentally related to dosimetric quantities of interest.
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