ウラン・トリウム系列核種と海洋での物質循環(1988年度日本地球化学会奨励賞受賞記念)

スポンサーリンク

概要

• 論文の詳細を見る

• This article summarizes the author's work on the distributions of U, ^<234>Th, ^<226>Ra, ^<210>Pb and ^<210>Po in seawater. Some recent studies of other investigators relevant to them are also reviewed. Removal of uranium from seawater occur in anoxic sediments where soluble U(VI) is reduced to insoluble U(IV). Radium isotopes are useful tracers for the study of water movement althouth distribution of ^<226>Ra is largely governed by the biogeochemical cycle. Based on the ^<226>Ra distribution and a boxmodel of the Japan Sea, the residence times of the Japan Sea Proper Water with respect to exchange with the surface water by vertical mixing and with the open ocean water were estimated to be 300〜400 years and 700〜1000 years, respectively. Measurements of ^<234>Th/^<238>U in the surface waters indicates that the degree of the radioactive disequilibrium is large in the northern North and the equatorial Pacific suggesting that the biological particles are responsible for ^<234>Th removal. In the deep sea, the removal of ^<210>Pb and ^<231>Pa occurs intensively in the high productivity areas. The increase of ^<210>Pb concentration was observed in the bottom water of Funka Bay in summer when the sediment became a weakly reducing condition. The concentrtion of ^<210>Po, the daughter nuclide of ^<210>Pb, was also extremely high in the bottom water of the anoxic marine lake in Palau. These observations suggest that lead and polonium are naturally mobilized in anoxic surface sediments.

• 日本地球化学会の論文
• 1989-06-30

著者

• 原田 晃

  北海道大学水産学部

関連論文

• 遠洋域でのセジメントトラップ実験で観測された234Th,210Po,210Pbのフラックス〔英文〕
• 噴火湾におけるTh-234の粒子束の実測値の計算値との差の季節的変動〔英文〕
• 海水中の234Th,226Ra,210Pb,210Poの実用的同時分析法〔英文〕
• 有限要素法を用いた非線形振動解析の低次元化モデル : 機械力学,計測,自動制御
• 海洋におけるPb-210,Po-210およびTh同位体の挙動(環境における放射性および安定同位体の動態,課題討論(富山,1986)
• 沿岸海域における天然放射性核種(ウラン,トリウム系列)の挙動とその応用
• ウラン・トリウム系列核種と海洋での物質循環(1988年度日本地球化学会奨励賞受賞記念)

スポンサーリンク