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34Th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—20×106dm3／kg之间，平均为2．2×105dm3／kdKd与总悬浮颗粒物含量（7SAN呈负相关关系：lg（Kd）＝－0．59·lg（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）。
234Th(T1/2= 24.1d), a particle-reartive radionticlide, is a useful tracer of particle dynamics in the upper ocean. In thes study, measurements of ashvities of dissolved and particulate 234Th by (counter were mad for 116 samples collected from the Nansha sea are4 the northeastem South Chna Sea the Xiamen Bny and the Jiulongiiang estuary during 1994-1995. The other of the pereentage of Particulate 234Th in the total is as folows: the Jiulongiiang estUaxy > the Xiamen Bay > the Nanha sea area ro the northeastem South China Sea which shows that the dissolved form is the dondnan Phase of 234Th in the open ocean, but in the nearshore sea are` especially in an estUary, 234Th is mainly in the particulaie form. The partihoning of elements between the particulare and the dissolved can be expressed as a condihonal distribution coefficienL The condihonal distribution coefficients, Kd' s, for 234Th in the studied sea area range from 1.1×104 to 2.0×106dm3/kg, with an average 2.2×10dm3/kg. There is a negative cormlation betWeen the lg(Kd) and the lg(mp. Ths 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 tha Cc =f(TSm0.59), where Cc represents the concentalon of mallne colloids in uns study area. Assuming that TSM is as low as 0.01mg/dm3, Kp,the distribution coefficient between particle and truly solution, for 234Th is 106.85, shows tha 234Th is a strong Particle-reactive element. The particle conceniration effect confirms the importance of marine colloids in the biogeochemical cycle of elements in marine environmnts. It is necessare to study marine colloids direcdy in the future to reveal the role of marine colloids accurately.
出处
《海洋与湖沼》
CAS
CSCD
北大核心
1999年第6期726-730,共5页
Oceanologia Et Limnologia Sinica
基金
国家"八五"科技攻关项目!85-927-04-04
国家自然科学基金
关键词
颗粒态
溶解态
条件分配系数
海洋胶体
钍234
^(234)Th Particulate Dissolved Conditional distribution coefficient Marine Colloids
