中文摘要：

根据2011年长江口浑浊带枯季悬沙粒度的实测数据分析,发现浑浊带悬沙粒度分布存在明显的时空差异,同时探讨了近20年的粒度变化过程。浑浊带粒度受动力驱动,大潮垂向分布差异显著且粒径较大,中值粒径表层在7μm左右,中层在10～20μm之间,底层在10～25μm之间;小潮期间垂线分布比较均匀且粒径较小,表中底三层中值粒径分布均在3～6μm之间,中值粒径沿水深的垂向分布梯度很小。浑浊带粒度的空间分布特征表现在：浑浊带核心区域,大潮悬沙粒度中约含有30%黏土,70%粉砂,砂含量较少,砂比例垂向上呈增加趋势;核心区悬沙粒度三组分沿水深的分布在大小潮两个时段变化幅度较大,而浑浊带外缘粒度随潮动力的变化幅度不明显。近20～30年间,浑浊带区域的悬沙粒度中值粒径经历了＂小-大-小＂的变化过程,三组分也同样经历了一个先粗化再细化的过程。

英文摘要：

Based on the observed data of grain size distribution of Yangtze River estuary turbidity maximum during the dry season in 2011,there were obvious spatial and temporal disparities of grain size distribution of suspended sediment. Variation progresses of grain size in the nearly 20 years were also discussed. The grain size distribution was driven by water dynamic and obviously varies along depth with larger particle sizes during spring tide,with the 7μm at surface layer,10 ～ 20μm at middle layer and 10 ～ 25μm at bottom layer median particle diameter. During the neap tide,the grain size was small and nearly uniform distributed,with median particle diameters about 3 ～ 6μm in surface,middle and bottom layer. In the core area of turbidity maximum during spring tide,the suspended sediment contained 30% clay,70% silt and little sand. The proportion of sand increased along depth. In the core area,three components distribution along depth of suspended sediment differed in spring and neap tide,which was nearly the same in the outer edge area. In the nearly20 ～ 30 years,the suspended sediment median particle diameters of turbidity maximum witnessed a ‘coarseness-fineness-coarseness＇ variation progress,which also can be proved in the view of three components.