Scavenging of 210Pb and 210Po in the coastal waters of the southern East Sea

Activities of 210Po, 210Pb and 226Ra in dissolved and particulate phases were determined to estimate the scavenging rate constants of the particle reactive nuclides in the coastal waters of the southern East Sea (Japan Sea) in April 1994. The most characteristic observation was the regeneration of 210Po from particulates to dissolved phase within the thermocline. In contrast, 210Pb were simply removed both in the surface mixed layer and thermocline without any sign of regeneration. The removal flux of 210Pb in the surface layer was significantly larger than that in the thermocline. In the surface layer, scavenging residence time of 210Po was estimated to be 2-10 years. The residence time of 210Pb was estimated to be approximately a year in the surface layer and longer than 30 years in the thermocline. (author)