苏北新洋港潮滩柱状沉积物粒度分布特征

GRAIN SIZE INFORMATION IN DIFFERENT EVOLUTION PERIODS OF XINYANGGANG TIDAL FLAT IN JIANGSU PROVINCE

通过对江苏省新洋港柱状样的粒度参数及典型粒度频率曲线分析,结合柱样剖面颜色变化情况,对柱状样进行不同演化阶段粒度信息的提取,运用粒径—标准偏差进行环境敏感性分析,以了解影响潮滩沉积物分布的动力特征。结果显示,光滩柱样呈现了由光滩—大米草滩—光滩逐渐演化的粒度变化信息,而互花米草滩、盐蒿滩和盐蒿互花米草混合滩柱样分别记录了大米草滩—互花米草滩、盐蒿滩—大米草滩—盐蒿滩,以及盐蒿滩—大米草滩—盐蒿互花米草混合滩演化的粒度信息,水动力条件的差异与变化导致沉积物水平方向上自光滩—互花米草滩—盐蒿滩逐渐变细,芦苇滩成为独立的系统,基本不受到潮水动力作用的影响,沉积结构十分稳定,植被的引种加剧了潮滩沉积物水平分布的变化,光滩、互花米草滩、盐蒿互花米草混合滩、盐蒿滩的沉积速率分别为2.34、≥3.09、2.45和2.09cm/a。

Six sediment cores were collected in Xinyanggang, Jiangsu Province, in August 2007. Sediment spatial distribution characteristics were studied by analyzing grain size. Grain size parameters and typical frequency distribution curves combining with the changes in color of different core sediments were analyzed for extraction of grain size information in different evolution periods. Standard deviation of grain size components was used for environmental sensitivity analysis to understand the impact of dynamic characteristics on distribution of tidal flat sediments. Deposition rates were estimated in accordance with the evolution periods of tidal flat. The results showed that, core sediment of silt Flat gave grain size evolution information from silt flat to Spartina angilica flat, and then to silt flat again. However, core sediments of Spartina alterniflora flat,Suaeda salsa flat and transitional Spartina alterniflora and Suaeda salsa flats recorded grain size evolution information of Spartina angilica flat-Spartina alterniflora flat, Suaeda salsa flat-Spartina angilica flat-Suaeda salsa flat, Suaeda salsa flat-Spartina angilica flat-transitional Suaeda salsa and Spartina alterniflora flats, respectively. The difference and variation of hydrodynamics in different positions of tidal flat led to the coarse-fine variety of sediments horizontally from silt flat-Spartina alterni- flora flat-Suaeda salsa flat gradually, and resulted in the fact that reed flat became an independent environmental system which was very stable. And vegetation covers impelled this process, which was evidently reflected in grain size variation of surface sediments. Deposition rates of silt flat, Spartina alterniflora flat, transitional Spartina alterniflora and Suaeda salsa flats and Suaeda salsa flat were 2.34 cm/a, 3.09 cm/a, 2.45 cm/a and 2.09 cm/a respectively.