Cosmic rays interaction with atmosphere

For radiocarbon, the standard ratio s is provided by the preindustrial atmosphere, for which 8 = 0. Cosmic rays interacting with atmospheric nitrogen were the main source of preindustrial radiocarbon. In the steady state, this source drsource is just large enough to generate an atmospheric delta value equal to zero. The source appears in equation 9 for atmospheric radiocarbon. Its value, specified in subroutine SPECS, I adjust to yield a steady-state atmospheric delta value of 0. The source balances the decay of radiocarbon in the atmosphere and in all of the oceanic reservoirs. Because radiocarbon has an overall source and sink—unlike the phosphorus, total carbon, 13C, and alkalinity in this simulation—the steady-state values of radiocarbon do not depend on the initial values. 

P and P are naturally produced in the atmosphere by cosmic ray interactions with atmospheric argon nuclei. They are then quickly scavenged onto aerosol particles, and delivered to the ocean surface predominantly in rain. The ratio of introduced to the oceans by rainfall... 

Most of the carbon taken in by plants during photosynthesis is in the form of carbon-12, which is not radioactive. However, a small amoimt of radioactive carbon-14 (half-life = 5,730 y) is produced in the upper atmosphere as a result of cosmic rays interacting with atmospheric gases. The carbon-14 atoms that result are incorporated into atmospheric CO, which we can denote as "CO. When COj is taken in by plants during photosynthesis, the glucose that is produced contains carbon-14. During the Ufetime of a plant—grass, herb, bush, or tree—the ratio C/ C becomes a relatively constant quantity. 

Carbon-14 is formed in the upper parts of the atmosphere from secondary neutrons formed by cosmic ray interactions with the atmosphere. The neutrons interact with common nitrogen ... 

Natural (half-life = 5,730 yr) is produced by cosmic-ray interaction with the atmosphere. It enters the oceans by exchange of CO2 between the ocean and atmosphere. The ratio of in the... 

Primary cosmic rays interact with the upper atmosphere to produce mesons (mostly ir mesons) and nucleons. Many p mesons (or muons), produced as decay products of ir-mesons during their passage through the air, constitute most of the cosmic radiation found in the lower atmosphere (Friedlander and others, 1964). 

The stable isotopes have nuclei that do not decay to other isotopes on geologic timescales, but may themselves be produced by the decay of radioactive isotopes. Radioactive (unstable) isotopes have nuclei that spontaneously decay over time to form other isotopes. For example, C, a radioisotope of carbon, is produced in the atmosphere by the interaction of cosmic-ray neutrons with stable... 

A number of radioactive isotopes produced primarily by cosmic ray interactions in the upper atmosphere, especially (Clark and Fritz, 1997 Mazor, 1997), C1 (Andrews etal., 1994 Phillips, 2000), and (Moran et al., 1995 Fabryka-Martin, 2000), as well as dissolved " He (Torgersen and Clarke, 1985 Solomon, 2000), have been used, in conjunction with data for the stable isotopes and calculated flow rates, for determining the age of natural waters, including fluids in sedimentary basins (Bethke et al., 1999, 2000). The 5.73 ka half-life of " C at 5.73 ka is so short that it is useful only for dating basinal meteoric water younger than —40 ka. C1 (ti/2 = 0.301 Ma) is useful for dating water of up to —2 Ma in age. These isotopic systems are reviewed by Phillips and Castro (see Chapter 5.15). 

The main source of natural C is the upper atmosphere, where it is formed by the interaction of cosmic ray neutrons with N as a /3 emitter it returns to the original form, N, after ejection of an electron from its nucleus. About 100 " C atoms are being generated over each square centimeter of the earth s surface each minute. ... 

In order to date organic materials less than about 50 000 years old, the radioactive decay of carbon-14 is preferred. Carbon-14 is produced at a steady rate in the Earth s upper atmosphere as a result of the interaction of cosmic ray neutrons with nitrogen ... 

Cosmogenic radionuclides are formed in the upper atmosphere by the interaction of cosmic rays, primarily from the sun, with elements present in the atmosphere (e.g. 0, and " Ar). Their half-lives range from months to... 

The two isotopes of carbon that occur naturally are 12C (98.89%) and 13C (1.11%). Cosmic rays produce neutrons that interact with 14N in the upper atmosphere to produce 14C and protons,... 

The decay of radioactive isotopes created in the earth s atmosphere by the interaction of cosmic rays with atomic nuclei of atmospheric constituents. After such nuclei (e.g., 3H as 3HH0 or 14C as 14C02) are removed from the atmosphere, e.g., fed into a groundwater system (3H) or built into a living organism (14C), their number decreases according to the law of radioactive decay. 

Radiocarbon (14C) is produced in the atmosphere by the cosmic ray neutron flux interacting with 14N[14N(n,p)14C], The 14C hot1 atom then equilibrates with atmospheric C02 which participates in the C-0 cycle and passes into the food chain (biosphere). Most of the radiocarbon is taken up by the oceans which constitute the largest reservoir of C02 within the secondary geochemical cycle. 

Hydrogen has two stable isotopes, H (0.99985) and (0.00015), and a short-hved radioactive isotope iH (tritium) produced in the atmosphere by interaction of with cosmic ray neutrons ... 

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