Spatial variability and representation of seabed sediment grain sizes:An example from the Zhoushan-Jinshanwei transect,

Grain size analysis was undertaken for the 2-cm interval sub-samples of eight short cores collected along the Zhoushan-Jinshanwei transect in Hangzhou Bay, using a Malvern Mastersizer 2000 laser particle size analyzer. The result indicates that there are different vertical distribution patterns of mean grain size for the short cores. In the study area, the thickness of the seabed moving layer on an annual temporal scale is much larger than that of the deposited layer, i.e. the sedimentary environment is highly dynamic. As a result, the vertical distributions of mean grain size within the short cores represent different types of sedimentary records formed in the same environment, rather than signals of long-term environmental evolution. The seabed sediment consists mainly of silts in the study area, and the vertically-averaged value of mean grain size has a tendency of convergence when the thickness over which the mean value is derived increases. Such patterns indicate that the grain size composition of the deposit is controlled mainly by the source of material supply; nevertheless, to some degree hydraulic sorting is effective, which has resulted in the differences in distribution patterns along the transect between the grain size values of the surficial sediment and the vertically-averaged values. For long-term sediment transport modeling for an environment associated with strong tidal action and silty sediment, it may be more appropriate to use the vertically-averaged grain size than the value for the surficial sediment, as the model input.

作 者： ZHOU Xiaojing GAO Shu   作者單位： ZHOU Xiaojing(Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China)

GAO Shu(Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, China) 

刊 名： 科學通報（英文版）  SCI 英文刊名： CHINESE SCIENCE BULLETIN  年，卷(期)： 2004 49(23)  分類號： P7  關鍵詞： grain size analysis of short cores   vertical distribution of grain size   seabed mobility   Hangzhou Bay