| 摘要: |
| 1994–1995年期间，利用β计数法实测了南沙群岛海域、南海东北部海域、厦门湾塔角附近海域和九龙江河口区共计116份海水样品中溶解态与颗粒态234Th的放射性比活度。结果表明，颗粒态234Th占总234Th的份额大小顺序为：九龙江河口区＞厦门海塔角附近海域＞南沙海域≈南海东北部海域。234Th的条件分配系数Kd介于1.1×104–2.0×106 dm3/kg之间，平均为2.2×105 dm3/kg。Kd与总悬浮颗粒物含量（TSM）呈负相关关系：lg(Kd)=-0.59lg(TSM)＋5.67，这一“颗粒物浓度效应”可归因于海洋胶体物质的存在。由上述关系获得4个研究海区胶体浓度与悬浮颗粒物浓度的函数关系：Cc＝f(TSM0.59)。 |
| 关键词: 234Th 颗粒态 溶解态 条件分配系数 海洋胶体 |
| DOI： |
| 分类号: |
| 基金项目:国家“八五”科技攻关项目，85-927-04-04号;国家自然科学基金资助项目，49706069号 |
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| THE ROLE OF MARINE COLLOIDS ELUCIDATED BY THE PARTICLE / SOLUTION DISTRIBUTION OF 234TH |
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CHEN Min, HUANG Yi-Pu, QIU Yu-sheng
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Department of Oceanography, Xiamen University, Xiamen, 361005
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| Abstract: |
| 234Th (T1/2=24.1d), a particle-reactive radionuclide, is a useful tracer of particle dynamics in the upper ocean. In this study, measurements of activities of dissolved and particulate 234Th by (counter were made for 116 samples collected from the Nansha sea area, the northeastern South China Sea, the Xiamen Bay and the Jiulongjiang estuary during 1994–1995. The order of the percentage of particulate 234Th in the total is as follows: the Jiulongjiang estuary > the Xiamen Bay > the Nansha sea area ≈ the northeastern South China Sea, which shows that the dissolved form is the dominant phase of 234Th in the open ocean, but in the nearshore sea area, especially in an estuary, 234Th is mainly in the particulate form. The partitioning of elements between the particulate and the dissolved can be expressed as a conditional distribution coefficient. The conditional distribution coefficients, Kd's, for 234Th in the studied sea area range from 1.1×104 to 2.0×106 dm3/kg, with an average 2.2×105 dm3/kg. There is a negative correlation between the lg(Kd) and the lg(TSM). This so called “particle concentration effect” may a result from the presence of colloidal 234Th in the filter-passing fraction. The slope of the lg(Kd) versus lg(TSM) plot indicates that Cc＝f(TSM0.59), where Cc represents the concentration of marine colloids in this study area. Assuming that TSM is as low as 0.01 mg/ dm3, Kp, the distribution coefficient between particle and truly solution, for 234Th is 106.85, shows that 234Th is a strong particle-reactive element. The particle concentration effect confirms the importance of marine colloids in the biogeochemical cycle of elements in marine environments. It is necessary to study marine colloids directly in the future to reveal the role of marine colloids accurately. |
| Key words: 234Th, Particulate, Dissolved, Conditional distribution coefficient, Marine colloids |
