珠江口磨刀门枯季表层沉积物特征

Characteristics of bed sediments during the dry season in the Modaomen estuary of the Pearl River

根据2003年12月在珠江口磨刀门附近水域采集的河口表层沉积物粒度分析资料,研究了磨刀门河口表层沉积物的组成、分布、运动等特征及其动力环境指示作用。研究表明,磨刀门口枯季表层沉积物组成以粉砂为主,其次为粘土和砂。表层沉积物平均中值粒径为6.356(0.0122mm),表层沉积物的级配与悬沙的级配较接近。口门附近表层沉积物的中值粒径、分选性沿程没有明显的变化。枯季表层沉积物的形成以悬移质沉积为主,跃移和推移运动形式很少。磨刀门由于受人类活动的影响枯季表层沉积物与历史相比出现明显的细化,磨刀门口附近枯季表层沉积物的特征在一定程度上反映了枯季以潮流作用为主的相对较弱的动力环境。

Based on the grain size analysis of bed materials sampled from the Modaomen estuary of the Pearl River in December 2003, the gradation, distribution and transport properties of bed materials and their indication of dynamic environment have been studied. It has been showed that in the Modaomen estuary, the bed sediments are mainly composed of silt, and clay and sand in the next place; the mean median grain size is 6.356(0.012 2 mm); the gradation of bed sediments and that of suspended sediments are similar; the mean median grain size and sorting coefficient of the bed sediment have no big changes in Modaomen estuary area; the suspension is the main transport form of the sediments; and the bed load and saltation transport seldom take place. Owing to the intense human activities, the grain size of bed sediments is becoming finer than that in the past. The characteristics of the bed materials during the dry season in the Modaomen estuary indicate that the weak dynamic environment and tidal current are the main dynamic process.