Distribution of3H,137Cs and239,240Pu in the surface seawater around Korea

The concentrations of³H,¹³⁷Cs and^239,240Pu were determined in surface seawaters collected at 21 sampling stations around Korea from October of 1994 to May of 1995. The results were consistent with the past data observed in the North Pacific. The concentrations of³H and¹³⁷Cs did not show much difference no matter where the samples were taken. Due to the limited distribution of sampling points, no systematic change in³H and¹³⁷Cs levels with latitude was observed. On the other hand,^239,240Pu concentration in the East Sea (Japan Sea) was somewhat higher than that in the South and the Yellow Seas, although the data on^239,240Pu concentration were not enough to explain the reason. The activity ratios of^239,240Pu/¹³⁷Cs in surface seawater ranged from 0.13% to 0.44% with a mean of 0.25±0.08%. The activity ratios were lower than those of the global fall-out level, 1.1%. This result presumably arose from the different behavior of the two radionuclides in seawater.