秋季东山乌礁湾海滩表层沉积物粒度特征分析

Analysis on grain size characteristics of surface sediments of Wujiao Bay in Dongshan sea area in autumn

以东山乌礁湾为典型研究区,对海滩5条剖面表层沉积物进行样品采集（0~5 cm）和点位测量,综合应用激光法和筛析法进行粒度测定.结果表明秋季东山乌礁湾表层沉积物以粒径0.16~0.50 mm的砂为主,具有较好的分选性,符合岬湾砂质海滩表层沉积物的一般组分规律和分选特点;粒径分布表现出由南向北逐渐变细的区域差异性,主要是岬湾地形影响下的季节性风浪作用结果;从高潮带至中潮带站位主峰值粒径逐渐增大,粗粒含量增多,至低潮带主峰值粒径变小,粗粒含量降低,是近岸往复水动力作用和剖面地形作用的结果;总体看乌礁湾表层沉积物粒度分布主要受岬湾海岸地形特征和季风影响下的波浪、潮汐等水动力作用以及湾内局地物源输入的影响.

To understand the grain size characteristics and distribution of surface sediments over the cape-bay coast,Wujiao Bay of Dongshan sea area were taken as a typical area for the study. Surface sediment samples were collected from 5 profiles perpendicular to the Wujiao Bay coastline,each of them were taken from 0 to 5 cm. Grain sizes of the surface sediments were analyzed by Mastersizer 2000 laser particle size analyzer. Sampling position and profile altitude were measured by GPS. Results showed that,sandy sediments（ 16 ~ 500 μm） were the primary particles in the study area,and sand-sorting was much better,which agreed with the sediment characteristics of Southern China. Grain size distribution trended to be smaller northwards in Wujiao Bay,which resulted from the capebay coast geomorphology and the dynamic effect of wind wave. Peak value of grain size distribution curves along the profile increased from nearshore waters to the middle tidal zone while decreased to the low tidal zone,caused by the offshore hydrodynamic environment and coastal landform. In general the comprehensive effects,such as the capebay geomorphology,wind-wave,tidal effect,and local sediment provenance,contribute to the characteristics of grain size distribution in Wujiao Bay.