Study on Changes of Radionuclides Concentration in Pine Needles on Pref. Ishikawa and Its Transfer Process during Two Decades.

Abstract

Changes of Radionuclides concentrations, i.e., 137Cs, 7Be and 40K, in pine needles were investigated in some sampling stations in Pref. Ishikawa during two decades. From 1979 to 1989, artificial nuclide 137Cs had been detected in pine needles, soil and air-suspended particles because of Chinese nuclear weapon test (1979) and Chernobyl's nuclear power plant accident (1986). But since 1990, 137Cs was hardly detected in pine needles except a particular area where 137Cs accumulated in soil, while natural nuclides, 7Be and 40K, were detected in pine needles and soil. It was found that radionuclides transfered into pine needles by deposition on leaf and adsorption from root. It seems that in eayly decade both deposition and adsorption dominated as a transfer process in pine needles, but in a later decade, only adsorption dominated.