摘要：
海洋沉积物的来源、输运过程及其归宿一直是海洋沉积学的重要研究课题.浙闽沿岸泥区的沉积物主要来自长江及浙闽沿岸的中小河流,对后者的贡献量进行定量化分析是相关研究比较薄弱的环节,这个问题的难点可能是缺乏同时指示"物源"和"供应量"两个指标的示踪物.本文以椒江和瓯江这两条河流对浙闽沿岸泥区的贡献为切入点,运用了粒度端元和黏土矿物两种示踪指标进行研究,目的有两个:一是综合评价两种示踪指标的效率,二是定量化地了解中小河流对浙闽沿岸泥区的贡献.借助端元粒度分析模型对浙闽沿岸泥区的表层样粒度数据进行分解,划分出4个不同的端元,结果显示,EM1端元表现出长江来源的属性,EM2端元表现出椒江和瓯江等沿岸中小河流来源的属性,EM3端元可能来源于研究区南部并有向北输送的趋势,EM4端元可能来源于陆架中部的残留砂沉积区.基于特征粒级的进一步分析表明,研究区6个站位的柱样沉积物中都出现了第一特征粒级,在3.91~9.29 μm之间,推测与长江口外悬浮颗粒物有关,并认为柱样所在的区域都会受到长江入海泥沙的影响.黏土矿物由于具有粒度依赖性,在定量探讨椒江与瓯江的泥沙贡献量时,只能指示小于2 μm的细颗粒物的贡献量,而粒度端元作为一种"全粒度"的指标,在相对封闭的系统内,可以同时解答"从哪里来"和"有多少"这两个示踪问题,是受限比较小的示踪物指标,未来在定量研究物源方面可能会有较大的作用.%Source,transportation and fate of marine sediment are among the crucial questions in oceanographic sedi-mentology.As well known,the materials of so called Zhe-Min coastal mud are mainly derived from the Changjiang River as well as the medium and small rivers throughout Zhejiang and Fujian Provinces.However,we still have little knowledge on the quantitative contribution of those medium and small rivers to that mud zone,probably due to the lack of suitable tracers.Using grain-size end member and clay minerals as tracers,this paper aims to 1)e-valuate the efficiency of two tracers comprehensively,and 2)quantify the individual contribution of Jiaojiang River and Oujiang River.An end member model was used to analyze the grain size data of surficial sediment samples and 4 end members were identified.End-member 1 is attributed to the Changjiang River input.End-member 2 is caused by the input of small rivers,such as Jiaojiang River and Oujiang River.End-member 3 is associated with the input from the south part of study area and probably indicates a possible transport towards the north.End-member 4 is possibly transported from the residual sandy area.Furthermore,the graph of standard deviation values of grain-size content against grain-size classes of six cores in the mud area reveals characteristic populations of grain-size.It shows that all cores have a common characteristic population (primary peak)of grain size between 3.9 1 to 9.29 μm,which is associated with the fine particles suspended from the Changjiang River delta and perhaps indicates that the overall study area is affected by Changjiang River.Based on a matrix method model,data of clay minerals contents are used to evaluate the quantitative contribution of Changjiang River,Jiaojiang River and Oujiang River to the coastal muds.Due to the dependence of the clay minerals on the grain-size,the results merely reflect the contribution of fine particles less than 2 μm.In comparison,the end members of grain-size are better tracers which include the entire level of fraction to simultaneously solve both of problems about"source and quantification"in a relatively closed system.Therefore,the end-member analysis of grain size is expected to play a significant role in the future.
