江苏大丰潮滩底质与悬沙的粒径组成特征

2002年和2003年夏季在江苏大丰潮滩上采集了表层底质和悬沙样品,分析了潮滩不同部位的底质与悬沙的粒径组成特征及其影响因素.研究结果表明,潮滩表层底质具有明显的空间分带性,底质泥沙的来源和堆积方式（悬沙沉降和推移质输运）以及植被覆盖状况是影响底质空间分布的重要因素.悬沙粒径组成在潮周期内的变化有两种模式,一是稳定型,悬沙级配的时间和空间变化很小;二是双峰型,悬沙级配的时空变化显著,粗细峰强度不断转换.再悬浮、沉降、涨潮时输入潮滩的悬沙和底质级配是影响悬沙粒径组成的主要因子.悬沙与底质在粒径组成上差异明显,再悬浮和沉降是联系二者粒径组成关系的纽带.悬沙沉降对底质的泥沙贡献率从潮滩下部向上部不断增加,在互花米草滩上至少为79%.

Characteristics of grain size distributions of seabed and suspended sediment over the Dafeng tidalflat of Jiangsu Coast

Grain size distributions of seabed and suspended sediment samples from several sites on the Dafeng tidalflat,northern Jiangsu coast,collected in July and August of 2002 and 2003,were analyzed.The results show that the seabed-sediment can be divided into different types from lower to upper parts of the flat in terms of grain size parameters;the sources and mode of sediment movement of the seabed sediment(consisting of suspended material and/or bed-load) and the saltmarsh vegetation are the main factors to influence the spatial distributions of seabed sediment.Two types of grain size distributions of suspended sediment according to the temporal-spatial variations during the tidal cycle can be identified.One is the stability type with small variations;the other is the double-peak type associated with a "double-peak" characteristic in the grain size distribution curve,with remarkable variations.The main factors that affect the grain size distributions of suspended sediment include localized resuspension and settling process,suspended sediment transported onto tidal flats during the flood phase of the tide,and the spatial distribution pattern of seabed sediment.The difference in gain size distribution between the seabed and suspended sediments is significant.The relationship between the two distributions can be explained by resuspension and settling processes.