珠江河口沉积物粒度特征及其对底层水动力环境的指示

珠江口伶仃洋及邻近海域沉积物粒级变化大。频率分布曲线形态的变化揭示了珠江河口不同区域泥沙来源的差异。在平面分布上,粗粒级含量从西北部和北部向东南部迅速降低,而细粒级含量高值往往出现在河口中部。表层沉积物平均粒径梯度变化方向与珠江口悬浮物的运移方向大致吻合。反演获得的底层海流不同区域的优势速度与实测资料相符。两者较好地指示了沉积物多年平均优势海流速度和方向,表明利用沉积物粒度数据比较成功地反演出了珠江口沉积物推积前的搬运水动力环境。

Characteristics of Sediment Grain Size and Their Implications for Bottom Hydrodynamic Environment in the Pearl River Estuary

Analysis of sediment grain size showed that the grain size grade changed greatly in the Pearl estuary. Frequency distribution curves indicated the different sources of the suspended matters in the Pearl River estuary. In spatial distribution, content of coarser sediment component decreased quickly from north and northwest to southeast. However, finer sediment component always had higher contents in the middle of the estuary where a turbidity maximum zone existed, which was related to the resuspension and flocculation in this zone. Mean grain sizes and coarser components of sediments were successfully used to inverse the direction and velocity of bottom currents before the accumulation of sediments. The grade direction of mean grain sizes was basically coincident to the transport direction of the suspended matter. The predominant velocity of bottom current in various zone were consistent with data obtained on-the-spot survey.