连云港近岸海域表层沉积物沉积特征及粒径趋势分析

Surface sediment characteristics and gran size trends of Lianyungang coastal waters

对2013年在连云港近岸海域采集的170个表层沉积物进行了粒度分析,以得到的粒度参数探讨其沉积物分布特征与物源和水动力环境的关系.结果表明,研究区底质类型主要有泥、砂质泥、粉砂、砂质粉砂与粉砂质砂.总体趋势为近岸细、远岸粗,由岸向海呈现条带状分布.依据海底地形差异及水动力条件结合底质类型可将该地区划为3个区域:Ⅰ海州湾区、Ⅱ航道区、Ⅲ灌河口北侧砂质区.海州湾与航道区的沉积物都属于低能弱流环境下的产物,近岸区域以粉砂为主,远岸以砂质粉砂为主;砂质区沉积物则相对较粗,主要成分为粉砂质砂,受到了较强的波浪掀沙与潮流冲蚀.利用Gao-Collins模型对平均粒径、分选系数、偏态系数进行了趋势分析,得到了粒径运移趋势图,揭示了研究区内沉积物输运的趋势,连岛西北部与灌河口北部有较小辐聚区,海州湾北部沉积物运移方向为西南向,表现为向岸运移,与该区域的涨潮流方向一致;徐圩航道中段南部运移趋势较紊乱,是受到了航道疏浚与抛泥的影响.

A total of 170 surficial sediment samples were collected in the Lianyungang coastal waters in 2013,and the characteristics of grain-size was analyzed for the provenance and hydrodynamics condition. The result shows that the samples can be classified into 5 types as mud,sandy mud,silt,sandy silt and silty sand. The grain size diameters decrease landward with decreasing hydrodynamics,showing a banding distribution from the coast to the sea.Based on the submarine topography,hydrodynamics condition and sediment types,the sedimentary environments ofLianyungang coastal waters can be divided into 3 patterns,i. e. I Haizhou Bay,Ⅱ Channel area and Ⅲ Sandy region in the north of Guanhe estuary. Sediments in Haizhou bay and the channel area were formed in the weak current of sedimentary environment,where inshore area is mainly composed of silt while offshore area consists of sandy silt. However,the sandy region had a stronger tidal current environment and coarser grain size. Used the Gao-Collins model,sediment transport trends were mapped and analyzed against the mean size,sorting coefficient and skewness. The trend analysis for the grain size shows that there are 2 convergence zones,one in the northwest of Liandao and the other in the north of Guanhe estuary. Sediment transport trends to the south west in northern Haizhou bay and it is coincided with the rising tide. The sediment transport trends is quite chaotic in the south of Xuwei channel due to dredging and dumping operations.