Transuranic nuclides in two coastal marine sediments off Peru

Abstract

The fluxes of plutonium isotopes, as well as their depth profiles, are similar for northern and southern hemispheric varved sediments taken off western American coasts. The inventories are in excess of the values predicted for atmospheric fallout In these anoxic sediments there is a general increase in concentration from depths to the near surface. These observations are explainable on the bases that anoxic deposits have a substantially higher retentivity of sedimented materials compared to that of their bioturbated oxic counterparts and that there are inputs of resuspended materials previously deposited in the marine environment. The 241 Am distributions are explained by ingrowth from 241 Pu assuming a substantial input of the parent from the U.S. thermonuclear tests during the 1950's and the immobilization of both Pu and Am in the deposits.