Radium-228 in the Japan Sea

Abstract

The distribution of²²⁸Ra in surface and subsurface waters in the Japan Sea was studied. The concentrations of²²⁸Ra in surface waters were around 100 dpm/1000lwhich were much higher than those reported for Pacific surface waters. The concentrations of 228Ra decreasedwith increasing depth to less than 10 dpm/1000lin the Japan Sea Proper Water. Based on the comparison between observed values of²²⁸Ra andcalculated profile through the near-surface water mass and the underlying main water mass in the Japan Sea, the apparent verticaleddy diffusion coefficient was estimated to be about 2 cm²s^-1.