Stratospheric Fallout of Strontium-89 and Barium-140

Abstract

A series of nuclear test explosions which occurred in the fall of 1958 caused a very large increase of Sr⁸⁹ and Ba¹⁴⁰ in the stratosphere. The Ba¹⁴⁰/Sr⁸⁹ ratio in the stratosphere, and hence in the troposphere, has decreased steadily since then with a half-life of approximately 17 days.