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 Bq m -3 and 7.51-34.3 Bq m -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 cm2 s -1.