Mankind, increasingly crowding the earth, modifies the earthly environment in uncounted subtle and unpredictable ways, too rarely to the benefit of either earth or man. In this century it has become critically important that we comprehend more precisely than ever before the biological mechanisms and balances of our environment and that we learn to detect changes and to understand what they imply.

The release of atomic energy added a new dimension to the possibility of environmental change. In man’s first experiments with atomic energy, he added small but perceptible amounts of radioactivity to the earth’s natural total; as the Atomic Age matures, he inevitably will add more. But, in the course of his experiments, man has come to realize that environmental and biological studies, which now are necessary because of the use of atomic energy, may help solve not only the problems atomic energy creates but also the larger problem of how to manage wisely the world’s limited natural resources.

This booklet describes the environmental investigations that have been conducted with the aid of the atom since the first atomic detonation near Alamogordo, New Mexico, in 1945. The earth’s mysteries, however, are not easily unlocked, and investigations of our environment with atomic tools have only begun. The story thus is one of beginnings—but of beginnings that point the way, it is hoped, to a new understanding of the world in the atomic future.