Part 9

Plankton are the floating, minute plants and animals that live in the sea (and also in fresh water), including diatoms, algae, protozoans, and crustaceans.

For more on this program, see Plowshare, a companion booklet in this series.

The half-life of a radioactive element is the time required for half its atoms to lose their radioactivity.

Atmospheric tests of nuclear weapons through 1962 produced a fission yield equivalent to 191 million tons of TNT and introduced about 10.01 megacuries of strontium-90, for example, as fallout entering the environment.

Floating one-celled animals.

A picocurie is one trillionth of a curie; a curie is the basic unit of intensity of radioactivity, approximately equal to that in 1 gram of radium.

For more about these studies, see Fallout from Nuclear Weapons Tests, a companion booklet in this series.

Information on this research is found in Radioactive Wastes, a companion booklet in this series.

The lake, drained in 1955, makes an interesting natural basin in which residual radionuclides are used in studies of mineral cycling.

A roentgen is a unit of exposure to radiation, measuring the alteration of the atoms (ionization) of the radiated tissues. The rat dosages compare with recommended limits of exposure to man-made radiation for average individuals in human populations of an amount that approximates 0.5 roentgen per year.

The area where highest readings were obtained in the survey. These studies are described in more detail in Whole Body Counters, a companion booklet in this series.

Transcriber’s Notes

--Retained publication information from the printed edition: this eBook is public-domain in the country of publication.

--In the text versions only, text in italics is delimited by underscores.

--In the text versions only, superscript text is preceded by caret.

--In the ASCII version only, subscripted numbers are preceded by underscore and delimited by brackets.