257
radioisotopes
R
rad former unit of radiation dose, ~gray.
radiance the amount of light per unit area per unit solid angle from a certain
direction. Typically, measurement units are watts per square centimeter per
steradian.
radiation is used in different ways in oceanography. In the more common use it
refers to electromagnetic radiation (light, infrared radiation, ~optics), or to
radioactivity. It may also refer to other forms of energy transport, in particular by gravity waves.
radiation, background radiation caused by natural sources: cosmic radiation and
terrestrial radiation. Cosmic radiation constantly impinges upon the earth;
it originates within our own galaxy and at times of intense solar activity its
contribution from the sun increases considerably. Terrestrial radiation
stems from such naturally occurring isotopes such as 4oK, 87Rb, and nuclides
from the uranium and thorium series. Background radiation causes "noise"
in measuring, e.g., radioactive tracer activities and is therefore usually shielded off by lead.
radiation stress ~momentum density.
radioactive fallout ~fallout (radioactive).
radioactive waste ~ocean dumping.
radioisotopes or radionuclides are isotopes emitting alpha, beta or gamma radiation from their nucleus. The half-life ('r Il2 ) is a constant for a particular
nuclide, not dependent on any physico-chemical process. This property
makes radionuclides ideal for the determination of time scales, ages, and
rates by radiometric dating. From the measured and initial concentrations,
the decay after the incorporation of the isotope is determined, and the time
is calculated that has elapsed since incorporation took place. The most useful range for any nuclide is from 0.2 to 5 times T 112. According to their TI/2 and
sources, radioisotopes can be divided into three different categories: (a) isotopes with a very long T I12 , of the order of the age of the earth: 232Th, 238U,
235U, 4oK, 87Rb. To this category belong also series of daughters, granddaughters, etc. (e.g., all isotopes of Th, Pa, Ra, Rn and 21OPb), which are also
radioisotopes
R
rad former unit of radiation dose, ~gray.
radiance the amount of light per unit area per unit solid angle from a certain
direction. Typically, measurement units are watts per square centimeter per
steradian.
radiation is used in different ways in oceanography. In the more common use it
refers to electromagnetic radiation (light, infrared radiation, ~optics), or to
radioactivity. It may also refer to other forms of energy transport, in particular by gravity waves.
radiation, background radiation caused by natural sources: cosmic radiation and
terrestrial radiation. Cosmic radiation constantly impinges upon the earth;
it originates within our own galaxy and at times of intense solar activity its
contribution from the sun increases considerably. Terrestrial radiation
stems from such naturally occurring isotopes such as 4oK, 87Rb, and nuclides
from the uranium and thorium series. Background radiation causes "noise"
in measuring, e.g., radioactive tracer activities and is therefore usually shielded off by lead.
radiation stress ~momentum density.
radioactive fallout ~fallout (radioactive).
radioactive waste ~ocean dumping.
radioisotopes or radionuclides are isotopes emitting alpha, beta or gamma radiation from their nucleus. The half-life ('r Il2 ) is a constant for a particular
nuclide, not dependent on any physico-chemical process. This property
makes radionuclides ideal for the determination of time scales, ages, and
rates by radiometric dating. From the measured and initial concentrations,
the decay after the incorporation of the isotope is determined, and the time
is calculated that has elapsed since incorporation took place. The most useful range for any nuclide is from 0.2 to 5 times T 112. According to their TI/2 and
sources, radioisotopes can be divided into three different categories: (a) isotopes with a very long T I12 , of the order of the age of the earth: 232Th, 238U,
235U, 4oK, 87Rb. To this category belong also series of daughters, granddaughters, etc. (e.g., all isotopes of Th, Pa, Ra, Rn and 21OPb), which are also