Strontium 90 fallout in Antarctica

Abstract

Sr90 and gross β activities were measured on firn sections collected around Base Roi Baudouin, Scott Base, and South Pole Station. The firn layers were dated by stratigraphy and by oxygen isotope variations. The depth distribution of Sr90 and gross β activities revealed three radioactive horizons of potential glaciological application. The deepest horizon occurred at the end of 1953 as a result of the fallout of fission products from the Ivy test series, the second and most important one was formed in early 1955 by the debris of the Castle test series, and a third horizon, defined by a sudden increase in the gross β activity but not in the Sr90 content, was formed at the end of 1962. The rate of Sr90 deposition over Antarctica has been nearly constant since 1956, amounting to 0.2 and 0.1 mc/km2 yr at Base Roi Baudouin and at the South Pole, respectively. The cumulative Sr90 deposition up to January 1963 in the 70–90°S latitude belt is found to lie between 1 and 3 mc/km2.