长江口泥质区垂向沉积结构及其环境指示意义  

The vertical sedimentary structure and its implications for environmental evolutions in the Changjiang Estuary in China

作　　者：张瑞[1] 汪亚平[1] 高建华[1] 潘少明[1] 张志林[2] 

机构地区：[1]南京大学海岸与海岛开发教育部重点实验室 [2]水利部长江水利委员会长江口水文水资源勘测局,上海200136

出　　处：《海洋学报》2008年第2期80-91,共12页

基　　金：国家重点基础研究发展规划资助项目(2002CB412401);国家自然科学基金资助项目(40106009;40576040)

摘　　要：2006年4月在长江口泥质区获取了沉积物柱状样,进行了粒度分析及粒度分形计算,并从中提取沉积物环境变化敏感的粒度组分,结果表明,柱样的垂向沉积结构可分为两个部分：上部0-12 cm是动力环境改造频繁的活动层,沉积物混合程度较高;自12 cm以下沉积物有粗细旋回变化的特征,可能与长江入海泥沙的季节变化有关。本区沉积物主要含两个敏感粒度组分,标准偏差峰值为6.0-7.2μm的细组分与长江来源的悬沙粒径大致相当,而标准偏差峰值为40.7-57.5μm的粗组分则可能与风暴潮、波浪和潮流输沙、长江流域及河口区的水利工程的影响有关。沉积物粒度在0.9-20.3μm标度范围内的统计自相似程度很高,具有分形特征,粒度分维数的波动与沉积物粒度参数变化相吻合,表明沉积物粒度分维数具有一定的环境指示意义。The sediment grain-size and its fractal dimension of five cores collected in the Changjiang Estucary are analyzed, and then the environmental susceptive populations of grain-size are extracted. It is shown that the sediment cores can be divided into two parts according to the vertical sedimentary structure. The top part （i. e. , 0-12 cm） is the active layer which has been reconstructed frequently by dynamic environ-ments. The lower part from top of 12 cm to bottom, is characterized by coarse-fine sediment cycles. In addition, sediment is mainly composed of two susceptive populations of grain-size with 6.0-7.2 and 40. 7- 57.5 μm respectively, in which the former （i. e. , 6.0-7.2μm） is similar to grain-size of suspended sediment from the Changjiang River and the latter （i. e. , 40.7-57.5 μm） is associated with the effects of storm surges, waves and tides, dams and irrigation of river basin. The seasonal varations of suspended matter （e. g. , sediment supply quantity and grain size） from the Changjiang River may play an important role which contributes to the grain-size distribution in this area. The sediment has fractal features at 0. 9- 20.3 μm interval that is consistent with the changes of sediment grain-size index. Consequently, the fractal dimension of sediment grain-size can be an important potential index containing information on the environmental evolution.

关 键 词：粒度 沉积环境 分形 敏感组分 长江口 

分 类 号：P736[天文地球—海洋地质]