226Ra and 228Ra in the seawater of the western Yellow Sea

Radium isotopes ²²⁶Ra and ²²⁸Ra in seawater of the western Yellow Sea were measured by using the Mn-fiber adsorption—HPGe γ spectrum method. The distribution features of the two isotopes have been studied. The activities of ²²⁶Ra and ²²⁸Ra are 2.72–5.57 Bqm⁻³ and 7.51–34.3 Bqm⁻³, respectively. The activities of ²²⁶Ra and ²²⁸Ra from surface to bottom for each depth profile station are comparable within the experimental error, but the mean activities decrease with distance from the shore. From the distribution data of ²²⁸Ra, the horizontal eddy diffusion coefficient was estimated at 29×10⁶ cm²s⁻¹.