河北乐亭县祥云岛海域表层沉积物粒度及分布特征

Grain size and distribution characteristics of sediments in Xiangyun Island,Laoting county,Hebei province

通过对祥云岛近岸海域表层沉积物粒度分析,阐述了研究区沉积物粒级及分布特征,结合现场实测水动力数据,计算分析了研究区沉积动力条件。研究结果表明,祥云岛海域表层沉积物主要分为砂质粉砂(ST)、粉砂质砂(TS)、粉砂(T)和砂(S)四类,表层沉积物粒度中值粒径沿平行于祥云岛岸线方向由东北向西南方向逐渐变粗,垂直祥云岛岸线方向由近岸向远岸方向变细。研究区沉积物平均粒径主要集中在2~10Φ之间,沉积物粒度分布呈现单峰、双峰2种模式。表层沉积物以悬浮搬运为主,沉积物粒度分布特征与水动力条件密切相关,海流周期性的作用使得表层沉积物长期处于悬浮-沉降-再悬浮-再沉降过程中,细颗粒的沉积物不断被再悬浮带走,导致沉积物粒度发生空间上的分异。

Based on the grain size analysis of the surface sediments in Xiangyun Island,this paper described the grain size and distribution characteristics of sediments in the study area.The sedimentary dynamic conditions in the study area are calculated and analyzed combined with the field measured hydrodynamic data.The results show that:the surface sediments of Xiangyun island are mainly divided into four types:Sandy Silt(st),silty sand(TS),silt(T) and sand(s).The median grain size of surface sediments gradually coarsens from northeast to southwest along the direction parallel to the shoreline of Xiangyun Island,and narrows from near shore to far shore along the direction perpendicular to the shoreline of Xiangyun island.The average grain size of sediments in the study area is mainly concentrated in 2~10 Φ.The grain size distribution of the sediments shows two patterns:unimodal and bimodal.The surface sediments are mainly transported by suspension,and the grain size distribution of sediments is closely related to hydrodynamic conditions.The periodic effect of current makes the surface sediments in the process of suspension,sedimentation,resuspension and redeposition for a long time,and the fine sediments are continuously taken away by resuspension,which leads to the spatial differentiation of sediment grain size.