DISTRIBUTION OF TC-99 IN THE PACIFIC-OCEAN

Concentration of Tc-99 in seawater samples from the Pacific Ocean was determined by inductively coupled plasma mass spectrometry (ICP-MS). T he Tc-95m yield tracer for Tc-99 analysis was prepared by the Nb-93(al pha,2n)Tc-95m reaction in a cyclotron. The chemical yield of Tc-99 was determined by gamma-spectrometry of Tc-95m, which was added to the sa mple before analysis. Tc-95m does not interfere with Tc-99 determinati on by ICP-MS. The Tc-99 content in seawater from the Pacific Ocean is a few mu Bq l(-1), which is about an order of magnitude lower than pre viously reported values, obtained by beta-counting.