황해 방사성 핵종: 입력과 재분포

Abstract

The Yellow Sea is one of the marginal seas of the Northwest Pacific recieving large amounts of material from the continent via rivers and atmosphere. In order to understand the sources and present levels of key artificial radionuclides (90Sr, 137C and 239+240Pu) in the Yellow Sea, the processes affecting their distribution in the water column and their burial in the sea floor, concentrations of these radionculdies were determined in seawater and bottom sediment samples collected from the Yellow Sea during 1994 to 2000, and from the East China Sea and the tropical Northwest Pacific during 1993 and 1994. The atmospheric and riverine inputs of these readionuclides were also assessed at the mid-eastern coast of the Yellow Sea. The atmospheric deposition of these radionuclides appears to be dominated by the long–range tranport from the arid regions of the Asian continent with the highest values during the spring Asian dust storms and lowest in the summer wet monsoon period. The dry atmospheric deposition flux appeared to be particularly important for 239+240Pu. Riverine fluxes of these radionuclides dominated the total input due to the shear size of the riverine water and sediment fluxes into the sea. The river input was seeen in their distribution in the surface of the sea, particularly for 90Sr in winter. In summer, the water column stratification segregates these radionuclides vertically, so they are depleted in the surface layer and enriched in the bottom layer. The half-removal rate for 90Sr and 137Cs was estimated to be 7 years. The levels of radionculides in the Yellow Sea were higer than in the adjacent seas, and significant amounts of them have been exported from the Yellow Sea to the adjacent seas.