海州湾潮滩岩芯沉积物粒度特征及其环境意义

Grain Size Characteristics of Core Sediments and Their Environmental Significance in Tidal Flat of Haizhou Bay

通过对海州湾的野外考察、4根潮滩沉积物钻孔岩芯(HZ01、HZ02、HZ03和HZ04)的获取和室内岩芯沉积物粒度分析,探讨海州湾潮滩岩芯沉积物粒度变化特征,并指示其环境意义。结果表明:海州湾潮间带上、中部岩芯沉积物以粉砂为主,粉砂含量高于80%,而潮间带下部岩芯沉积物以粉砂和砂质粉砂为主,粉砂含量均值在65%左右,砂含量均值在10%左右。垂向变化上,潮间带上部岩芯HZ01沉积物粒径表现为从下往上,呈现由细变粗的趋势,潮间带下部岩芯HZ03和HZ04由下往上整体上表现为由粗变细的过程。空间分布上表现为由潮间带下部-潮间带中上部-潮间带上部呈现为由粗-细的空间变化特征。岩芯HZ01沉积物从下往上由细变粗的变化规律可能与1950's临洪河北侧大规模的围垦改变潮滩动力过程有关。潮间带下部岩芯HZ03和HZ04由下往上由粗变细的变化规律可能与临洪河输运泥沙在河口附近不断淤积并向海推进导致潮滩海拔高程逐渐增加、水动力逐渐减弱有关。潮滩沉积物在潮滩面上的空间分布规律反映了潮流是主要的动力条件,表现由海向陆的逐渐减弱过程。同时,粒度的空间分布也指示了外海、岚山头运移物质、废黄河沉积物和临洪河泥沙是重要的泥沙来源。

Abstract： The grain sizes of four sediment cores （HZ01,HZ02,HZ03 and HZ04） in tidal flat of Haizhou Bay were analyzed using laser particle size analyzer of Mastersizer 2000. The distribution characteristics of grain size in tidal flat of Haizhou Bay as well as the indications of their environmental significance were discussed. The results showed that the sediments in the mid-upper intertidal zone were mainly made of silts exceeding 80%. The sediments in the bottom of the intertidal zone were mainly composed of silts and sands, with the average contents about 65% and 10%, respectively. Sediment size of core HZ01 changed gradually from fine to coarse with the depth varying from bottom to top, while the oppo- site trend occurred for cores HZ03 and HZ04. The sizes changed gradually from coarse to fine from the bottom to mid-upper intertidal zones. The large-scale reclamation around northern Linhong estuary in 1950s possibly triggered the vertical changes in grain size of core HZ01. The changes in grain sizes in cores HZ03 and HZ04 were related to the deposition elevation and the weakening of hydrodynamic con- dition, because the Linhong River input sediments to the bay and expanded towards the sea continuous- ly. Spatial distribution of sediments from coarse to fine from bottom to mid-upper intertidal zones im plicated that the tide current was main hydrodynamic factor, which was weakening from the sea to the land. The sediments in Haizhou Bay originate from the open sea, the Lanshan Mouth, the abandonedYellow River and Linhong River.