长江北支口门圆陀角附近潮滩表层沉积物元素地球化学特征及物源意义

在圆陀角附近潮滩养殖区、盐沼区和光滩区共采集了22个表层沉积物样品,分析沉积物中19种元素含量及其分布,探讨圆陀角附近潮滩沉积物来源。研究结果表明,大部分常量和微量元素含量变化趋势较为一致(除Na、Ca、Ti、P和Sr元素外);常量和微量元素平均含量在不同采样区的大小顺序为:养殖区 < 光滩区 < 盐沼区。元素相关性分析和富集系数计算结果显示,圆陀角表层沉积物大部分元素来源较为一致,且平均含量与黄海沉积物元素平均含量接近,结合圆陀角附近沉积物粒径趋势、自西北向东南向延伸的沿岸沙坝、自北向南的沿岸流和辐射沙洲南翼恒大围垦大堤南侧的淤泥质潮滩沉积区综合分析认为,圆陀角附近潮滩沉积物主要来源于南黄海辐射沙洲南翼海区。

GEOCHEMICAL CHARACTERISTICS OF THE SURFACE TIDAL FLAT SEDIMENTS AT THE YUANTUOJIAO POINT,NORTH BRANCH OF CHANGJIANG RIVER AND IMPLICATIONS FOR PROVENANCE

The North Branch of the Changjiang River, to the north of the Chongming Island, was once the main channel of the estuary. Human reclamation and the south ward migration of the main channel led to the narrowing and shallowing of the North Branch. The Yuantuojiao Point is the intersection of the North Branch of the Changjiang River and the South Yellow Sea coastal line. The specific geographic location and the complexity of regional morphological dynamics jointly give birth to the typical silt-mud tidal flat. 22 surface sediments samples were collected on the areas of breeding, salt marshes and the mudflat at the Yuantuojiao Point. 19 elements both in contents and distributions were analyzed for the surface sediments. The main sources of sediments of the tidal flat near the Yuantuojiao Point were discussed according to the correlation analysis and elements enrichment coefficients. The study results indicate that the change trend is of difference among Na, Ca, Ti, P and Sr, but that of the other 14 elements has better consistency. The macroelements and microelements contents of the surface sediments have the highest on the salt marshes areas, the lower on the mudflat areas, and the lowest on the breeding areas. Calculation results of correlation analysis and enrichment coefficients of elements show that most elements of the surface sediments at the Yuantuojiao Point may have more coherent sources, and their average contents were similar to that of the Yellow Sea. Based on the grain size trend of surface sediments near the Yuantuojiao Point, the extension directions of alongshore bars and coastal current, and the comprehensive analysis of the muddy tidal flat sedimentary area, the south of Hengda levee at the southern part of submarine radial sand ridges, it is concluded that the sediments of the tidal flat near the Yuantuojiao Point is derived mainly from the southern part of the submarine radial sand ridges of the South Yellow Sea.