中文摘要：

基于近期在黄河三角洲附近海域采集的97个表层沉积物样品的粒度测试结果,研究了黄河三角洲海域表层沉积物的类型和空间分布特征,探讨了沉积物粒度分布特征与物源和沉积动力环境之间的关系。研究结果表明,研究区表层沉积物类型以砂质粉砂和粉砂为主,在绝大部分海域,表层沉积物的偏态表现为正偏和极正偏,分选程度较差,峰态表现为宽和很宽。现行河口三角洲叶瓣周围的表层沉积物以砂质粉砂为主,粒度较粗;而在远离河口的区域表层沉积物以粉砂为主,粒度较细。与20世纪80年代的观测结果相比,受物源供应和沉积环境的共同影响,近期黄河三角洲沿岸的表层沉积物有粗化的趋势,且河口口门区域表层沉积物粗化趋势最为明显。表层沉积物粒度粗化的主要原因是黄河入海泥沙供应不足,导致三角洲沿岸侵蚀加剧;黄河调水调沙以来入海泥沙的粒度变粗,粗颗粒组分在河口口门附近快速堆积。黄河水下三角洲现代沉积速率的分布特征表明,黄河入海沉积物主要在现行河口及三角洲的近岸区域沉积,在15m以深的区域沉积速率较低。同时,还可看出入海泥沙有向北和东北向的运移趋势,与渤海中部泥质沉积以及通过莱州湾向渤海海峡的泥沙输运相对应。粗颗粒沉积物在现行河口三角洲叶瓣的堆积范围与潮流切变锋的位置基本一致,反映了物源供应和沉积动力环境对研究区表层沉积物分布特征的控制性影响。

英文摘要：

Based on the grain-size analysis of surface sediments recently sampled at the subaqueous Yellow River Delta,the classification and spatial distribution of the surface sediment are presented.The results indicate that the surface sediments at the subaqueous Yellow River Delta are primarily composed of sandy silt and silt,mostly characterized by positive to strongly positive skewness,relatively poor in sorting,and wide to very wide kurtosis.The surface sediments around the presently active delta lobe are mostly sandy silt,relatively coarse in grain size,whereas the surface sediments are relatively fine-grained in offshore area away from the present river mouth.Compared with the investigation in 1980 s,the recent surface sediments at the subaqueous Yellow River Delta seem to be coarser in grain size.The significant changes might be attributed to the enhanced erosion along the delta coast due to insufficient sediment supply from the Yellow River.Meanwhile,the sediment delivered from the river to the sea has been much coarser since the Water-Sediment Regulation in 2002,which resulted in considerable accumulation of coarser sediments around the present river mouth.The distribution of sedimentation rate at the subaqueous Yellow River Delta indicates that the river-delivered sediments are mostly accumulated at the present river mouth and along the delta coast,together with northward and northeastward transport corresponding to the accumulation of fine-grained sediment in the central Bohai Sea and sediment export to the Bohai Strait through the Laizhou Bay,respectively.In addition,the high accumulation rate of coarse-grained sediments around the present river mouth implies the trapping effects from the tide-induced shear front.Our results indicate that both sediment supply and sedimentary dynamic environment play predominant roles in the distribution of surface sediments at the subaqueous Yellow River Delta.