Contamination of the Air by Radioactivity from the 1958 Nuclear Tests in the Pacific

Abstract

By the use of bomb-produced tungsten-185 tracer, debris from the 1958 nuclear tests (Hardtack) held at the U.S. Pacific Proving Ground have been identified as they appeared in the ground-level air along the 80th meridian. A large amount of radioactivity from these tests appeared in South America, particularly at the high-altitude collecting stations.

Chlorine-36 in the Terrestrial Environment

“…June 1958) at 65° Ν was about 4% of that at 30°Ν to 50°Ν (Lockhart et al, 1959), but this proportion is probably representative of only the early stages of fallout. Natural ^^Cl fallout at 65° Ν is about 30% of that between 30° Ν and 50°Ν (Bentley and Davis, 1981).…”

“…Pre sent-day bomb-tritium levels in the Southern Hemisphere are low due to the Arctic location of the major tritium-producing tests. ^^Cl was produced by equitorial tests, therefore its distribution should be approximately hemispherically symmetrical, as evidenced by W fallout from the Hardtack ex plosions (Lockhart et al, 1959).…”

Airborne radioactivity due to nuclear weapons tests

“…The rapidity of mixing in the troposphere is illustrated by the work of Lockhart et al [1959a], which indicated that debris from Hardtack I (Table 1) Except for impingement on surface materials (vegetation and minor variations in terrain), the removal of airborne activity occurs via rain and snow. During prolonged rains, a decrease in concentration of activity with time has been noted, implying a depletion of activity per unit volume of air; however, replacement by masses of air not similarly depleted is rapid, and a lower value of activity in air does not persist for more than a few hours under moderate rainfall conditions.…”