^(234)Th/^(238)U不平衡法及其在海洋颗粒物循环研究中的应用  

APPLICATION OF ^(234)TH/^(238)U DISEQUILIBRIUM TO THE STUDY OF MARINE PARTICLE CYCLING

作　　者：韦兵兵[1] 李江涛[1] 张利[2] 刘乾峰[1] 方家松[1,3,4] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]中国地质大学(武汉)地球科学学院地质过程与矿产资源国家重点实验室,武汉430074 [3]Department of Natural Sciences,Hawaii Pacific University [4]上海海洋大学海洋学院深渊科学技术研究中心,上海201306

出　　处：《海洋地质前沿》2015年第11期1-9,共9页Marine Geology Frontiers

基　　金：国家自然科学基金重点项目"评价嗜高压细菌在南海深部碳循环中的作用"(91328208)

摘　　要：一直以来,对于测定从海洋表层到深层整个全水柱的颗粒物输出通量都是一个很大的挑战。放射性元素^(234)Th因其合适的半衰期(t_(1/2)=24.1d)和超强的颗粒物活性而被广泛应用于示踪颗粒物的循环以及和生物有关的海洋过程,并且^(234)Th/^(238)U不平衡法因其采样简单且能得到高分辨率的垂向和水平向数据而具有更远的发展前景。主要介绍了^(234)Th/^(238)U不平衡法的原理、发展历史、采样和分析方法及其在海洋颗粒物循环过程和其他海洋学研究中的应用、存在的问题和发展前景,并重点探究其对于研究颗粒物有机物再矿化过程和受控机制以及深海碳循环的可能。In the past,scientists focused more on measuring ^（234）Th activity in the surface water,but overlooked its change in the deep ocean.In the＂twilight zone＂and the zone below it,the marine aggregates exported from sunlit euphotic zone will be altered by zooplankton and piezophilic microorganisms.These marine particles not only connect the surface and the deep ocean,but also are the most critical part of the global carbon cycle.However,it is a great challenge to determine the flux of marine particles from the surface to the deep ocean.The disequilibrium between ^（234）Th and ^（238）U has been widely utilized to study vertical transport,particle cycling and other biological processes.Its half-life of 24.1days and particle-reactive nature make ^（234）Th an ideal tracer for these processes on time scales of days to weeks.The method of ^（234）Th/^（238）U disequilibrium,based on the small-volume MnO_2 co-precipitation technique,is prospective for its easy sampling and high resolution.In this paper,we reviewed the principles,history,sampling,and analytical methods involved in the ~234Th/^（238）U disequilibrium,as well as the existing problems,and the development prospects of its application to aggregates cycling and oceanography.Further,we discussed the research potential of particle organic matter remineralization processes,its extent and the underlying acting mechanisms and the deep ocean carbon cycle.

关 键 词：234Th/238U不平衡法 海洋颗粒物 输出通量 再矿化过程 海洋碳循环 

分 类 号：P736.45[天文地球—海洋地质]