渤海湾西部表层沉积物粒度特征与沉积混合

根据渤海湾西部135个表层沉积物样品的粒度分析结果,分析了表层沉积物的粒度特征与规律。整体上由研究区东北部沿海岸向南沉积物粒度变细,由砂和粉砂质砂变为砂质粉砂,再变为粘土质粉砂。沉积物粒度频率曲线显示,由研究区东北部至北部,沉积物粗组分含量减少,由单峰逐渐过渡为主峰或弱峰,到中部粗组分减少为粗尾形态,到南部粗组分几乎缺失;而沉积物细组分的变化趋势则与之相反。沉积物粗组分在粒度频率曲线上的表现由单峰逐渐过渡至主峰或次峰,粗峰含量减少,到中部粗组分减少为粗尾形态,到南部粗组分几乎消失;而沉积物细组分的变化趋势则与之相反。沉积物粒度参数的平面分布规律和粒度参数之间的相关性变化形态显示出粗细2种母质组分以不同比例的沉积混合的特征,即来自东北部的粗组分与来自南部的细组分发生混合,这可能主要与区内双向的沿岸环流输运有关。

The grain-size characteristics and sediment mixing pattern of surface sediment from the western Bohai Bay, China.

135 samples were collected from the western Bohai Bay, a shallow semi-enclosed embayment in western part of Bohai Sea, to examine the surface sediment in grain-size characteristics. The surface deposits exhibit 4 main sedimentation types, respectively sand, silty sand, sandy silt and clayey silt. From northeast to south along the coast, surface sediment gets finer from sand, silty sand to sandy silt, and to clayey silt. And from northeast to north area, the grain size frequency distribution shows the coarser population decreases in content and changes from single mode to main or second mode gradually and is almost absent in south area. While the finer population changes following an opposite trend. The grain size parameters reveal a variable degree of mixture between coarser- and finer-grained hydrodynamic populations along the seashore. The sediment mixing pattern is probably associated with the two-way sediment transportation, caused by the complete changes of coastal circulation directions in different seasons.