汪额诺格岛(北海)与大陆之间障壁潮坪的沉积物:粘土矿物、重金属和有机碳

本文目的在于说明有限区域内潮坪小环境沉积物的矿物学和地球化学特点及沉积过程的改造作用。沉积物样品取自汪额诺格岛与联邦德国的德国湾南岸之间的障壁潮坪。粒度分析表明,障壁潮坪由大体平行于大陆的泥坪、混合坪到砂坪三个带组成。粘土矿物以伊利石为主,其次为蒙脱石、高岭石和绿泥石,与北海粘土矿物组合一致。粘土矿物组成和重金属Fe、Mn、Cu、Pb、Zn含量在潮坪不同部位相差无几,说明沉积物受到潮汐水流反覆侵蚀和再沉积作用的混合作用。近潮口附近有机碳含量增高是潮汐水流从北海通过进潮口携入有机物的结果。

SEDIMENTS DISTRIBUTED ON BACKSIDE TIDAL FLATSBETWEEN WAGEROOGE BARRIER ISLAND (NORTHSEA) AND MAINLAND,CLAY MINERAL,HEAVY METALAND ORGANIC CARBON

The aim of the present investigation is to demonstrate the mineralogy and geochemistry of the tidal flat microenvironment in a restricted area and to reveal their variation caused by sedimentation processes. The sedimentary samples taken from different places of the backside tidal flats between the Wagerooge barrier island and the mainland south coast, West Germany are used for grain size analysis and measurement of heavy metals: Fe, Mn, Cu, Pb, Zn and organic carbon. These samples are representative of the average characteristics of sedimentary column of 20cm depth under tidal surface. The grain size distribution on the tidal flats shows a general mainland-parellel zonation. The north salt marsh near the barrier island contains a plenty of sands blown from barrier island sand dune. Clay mineral composition and the content of heavy metals: Fe, Cu, Mn, Pb, Zn in 2μm fine fraction are almost equal in different places of the tidal flats. It indicates that there is no local input of them and tidal flat sediments have suffered the sufficient mixing induced by repeated erosion and resedimentation under the effect of tidal currents. In addition, in all samples illite as a dominent clay mineral is followed by smectite, kaolinite and chlorite, which corresponds to clay mineral association found in the North Sea. In the north and south salt marshes, there is the highest organic carbon content, which may be probably related to the in site formation. Near the tidal inlet organic carbon content increases relatively because most of organic carbon come from the North Sea with tidal currents through the inlet.