Atmosphere, interaction cosmic rays

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... 

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,... 

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. 

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 ... 

With the advent of nuclear weapons, particularly thermonuclear devices (hydrogen bombs), additional 14C was added to the atmosphere. This 14C, which we shall refer to as excess 14C, was produced by neutrons which escaped from the fireball interacting with nitrogen atoms of the atmosphere in the same manner as the neutrons from cosmic rays. Since the bulk of this 14C was probably produced by a few very high energy devices exploded high in the atmosphere, most of the excess 14C was likewise deposited in the stratosphere. 

C reaches the Earth s surface at the rate of 2.3 atoms/cm2/s after production by cosmic ray interaction in the atmosphere, corresponding to a total production of 1.4 x 1015Bq/y. 14C is also formed by the 14N(n, p) reaction by atmospheric tests of nuclear weapons. About 2.2 x 1017 Bq were made in the atmospheric test spike of the 1950s and 1960s that has been primarily transferred to the oceans and the biosphere. This means that 14C is the most significant fallout nuclide from the point of view of population dose. Nuclear power plants also release 14C as part of their normal operation contributing 0.1 x 1015 Bq/y. 

Tritium (3H) is produced naturally through atmospheric cosmic ray interactions via the reaction... 

Radiocarbon. Radiocarbon (14C) is unstable, with a half-life of 5730yr, and decays by emission of an electron to form 14N. It is continuously produced in the upper atmosphere by interactions of high-energy cosmic rays with the upper atmosphere. The 14C is oxidized to 14C02 within a few weeks and is then mixed into the troposphere (the lower, well-mixed part of the atmosphere), where it is taken up by plants during photosynthesis and exchanges with the surface waters of the ocean. 

Since radiogenic He has a 3He/4He ratio less than the air value, the only serious candidate for an alternative to primordial 3He is production by decay of tritium (3H). Cosmic ray interactions in the atmosphere are a well-known source of 3He (Section 5.5), and some of this is channeled through tritium, which will enter surface water... 

The interaction of cosmic ray particles within the Earth s atmosphere produces a cascade of secondary particles, many of which have enough energy to reach the... 

Cosmic ray neutrons interact in the upper atmosphere with nitrogen, producing 15N, which is radioactive and disintegrates into common carbon (12C) and tritium ... 

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 ... 

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