Estimate of the World Budget of Fallout Silver Nuclides

Abstract

THE increasing use of silver iodide in cloud-seeding has stimulated interest in the behaviour of silver in the marine environment. In view of this, more information about the ecological fate of fallout silver^1–4 is needed. Recently an estimate was made⁵ for the minimum northern hemisphere budget of ^110mAg created during nuclear weapons testing in 1961–62. This estimate was made from the concentration of ^110mAg measured in the livers of nine tuna fish caught in the North Pacific in 1965, together with the following assumptions: a concentration factor for silver in the livers over seawater of 500,000; a volume of the top 100 m of the North Pacific of 7.1 × 10¹⁸ 1.; and that the total area of the northern hemisphere is 2.55 × 10⁸ km². The estimated budget of ^110mAg over the surface layers of the northern hemisphere at the end of 1962 was computed to be at least 100,000 Ci.