1998 Volume 47 Issue 47 Pages 55-70
Radionuclides distribution and chemical components in the two cored sediments in the two Chinese lakes were studied, and the rates of sedimentation were determined. The average sedimentation rate of Lake Daihai (DH-1), the inland lake, was about 0.3cm/y, which is in the range of those reported in some Japanese lakes. It is suggested that the chemical composition varied a little as the source of sediments changed. On the other hand, the average sedimentation rate of Lake Blackspring (KS-2), the closed lake, was calculated to be about 0.1cm/y, which is 1/3 of DH-1. The samples around 16-18cm depth of KS-2 core where water contents and chemical components varied largely, were estimated to have deposited 160-180y ago, and thereafter the different sediment might deposit. The inventories of Cs-137 in the Chinese lakes were larger than those expected from its relationships with excess Pb-210 in the Japanese lakes. This fact indicates the larger amount of Cs-137 fallout in China than in Japan, and a little loss of Cs-137 in the Chinese lakes.