【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。更多还原

【Abstract】 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 environments.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.,6.0~7.2 μm) 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.更多还原