中国近海沉积物中钍同位素的分布  

Distribution of thorium isotopes in Chinese offshore sediments

作　　者：黄奕普[1] 施文远[1] 林永革 颜晓阳 

机构地区：[1]厦门大学海洋系,厦门361005

出　　处：《台湾海峡》1991年第4期302-314,共13页Journal of Oceanography In Taiwan Strait

基　　金：国家自然科学基金

摘　　要：本文对采自中国7个近岸海域的沉积物中钍(铀)同位素的分布进行了研究。发现表层沉积物中,^(230)Th/^(232)Th)_(A.R.)均小于1.0且呈均匀分布的态势。但^(230)Th/^(232)Th)_(A.R.)的数值及其深度分布特征与深海沉积物截然不同。^(230)Th/^(232)Th)_(A.R.)与水深呈良好的正相关。钍系不平衡普遍存在,其特征是^(228)Th/^(232)Th)_(A.R.)<1.0,据此推测了沉积物中可溶化学物质与上覆海水发生交换的深度。研究了沉积物中^(232)Th的含量、比度和^(232)Th/^(238)U)_(C.R.)的分布特征。从^(234)Th_(ex.)的深度分布求出秀屿站的表层混合系数(0.49×10^(-6)cm^2/s)和沉积柱中^(234)Th_(ex.)的总量。The study of thorium isotopes in the sediments from seven nearshore sea areas of China reveals a houcogeuous distribution and ^(230)Th/^(232)Th activity less than 1.0 in the surficial sediments. However, thevalues of ^(230)Th/^(232)Th)_(A.R.) and its depth distribution features in nearshore sediments are totally different from those in deep sea sediments. A well correlation between ^(230)Th/^(232)Th)_(A. R.) and sampling water depth was established. Thorium series disequilibria characterized by the deficiency of ^(228)Th relative to ^(232)Th generally exist in the nearshore sediments of China. The depths in sediments to which exchange of soluble chemicals with overlying water occurs are deduced. The content, specific activity of ^(232)Th and distribution features of ^(232)Th/^(238)U)_(C. R). in sediments are investigated. The surface mixing coefficient of 0.49×10^(-6)cm^2/s and the ^(234)Th_(ex). inventory in the core Xiuyu are estimated.

关 键 词：海洋 沉积物 钍 同位素 分布 

分 类 号：P736.44[天文地球—海洋地质]