珠江口河流输沙、河口沉积与粒度信息之间的联系

河口三角洲地区泥沙供应充分，是现代沉积速率较高的区域。快速沉积的泥沙包含高分辨率的环境信息。采用放射性同位素测年方法研究了珠江口伶仃洋大铲湾海域6个柱样的现代沉积速率，以2mm的间隔分析了其中2个柱样上部的粒度，并对其平均粒径和珠江流域的年输沙量进行了快速傅里叶变换，以期获取河流泥沙供应、河口沉积速率和沉积物垂向粒度变化的对应关系。结果表明，大铲湾海域的沉积速率为1～3cm／a，受动力条件和泥沙供应条件的影响显著。2个柱样的平均粒径的最显著重现周期与珠江年输沙量的周期性有较好的对应关系，并可能反映了季节的、年的和多年的沉积速率信息。对于每年沉积厚度在厘米级的环境，以毫米级的高分辨率进行粒度分析，有可能揭示出沉积物供应的季节变化和年际变化。本研究亦可为其他河口的相关工作提供借鉴。

Linkage of Grain Size Information With River Sediment Discharge and Estuarine Deposition at the Pearl River Estuary

The estuarine delta area is abundant in sediment supply,and is a high modern sedimentation rate area. The quickly deposited sediments contain high resolution environmental information. In this paper, the radioactive isotope dating method is used to study the modern sedimentation rates of 6 cores from the Dachan Bay, Pearl River estuary, and the grain size analysis at intervals of 2 mm is also made for the upper parts of two cores. The fast Fourier transformation (FFT) is made for the mean grain size and the annual sediment discharge in the Pearl River basin to derive the relationship between river sediment supply, estuarine sedimentation rate and vertical sediment grain size variation. It is shown from the analysis results that the sedimentation rate in the Dachan Bay sea area is in the range 1 to 3 cm/a, and is significantly affected by the dynamic and sediment supply conditions. There is a good correlation between the most signi-ficant recurrence periods of mean grain size of two cores and the periodicity of the annual Pearl River sediment discharge, which might reveal the seasonal and interannual variations of sediment supply. This study can also be used as a reference for other estuarine studies.