长江口及邻近海域表层沉积物中的生物硅

Biogenic Silica in Surface Sediments of Yangtze River Estuary and Adjacent Waters

对长江口及邻近海域表层沉积物中的生物硅进行了测定,分析了生物硅的分布特征及影响生物硅保存与分布的因素.结果表明：在整个海域调查范围内,表层沉积物中BSi含量范围为0.14％～0.70％,平均值为0.41％,与世界其他近海沉积物中BSi含量相比,处于中等偏下水平.黏土矿物和粉砂较多的沉积物中富集着更多的BSi,而砂含量较高的沉积物中BSi的含量较低.表层沉积物颗粒比表面积越大,越有利于BSi的赋存和累积.BSi的分布特征和TOC、TN分布存在一定的关联,说明2011年8月长江口及邻近海域表层沉积物中有机物的来源之一可能为硅藻;相对于TOC,BSi有更高保存率.表层沉积物表面富集着丰富的底栖硅藻,这是表层沉积物中BSi比同时期悬浮颗粒物中BSi的平均百分含量高一个数量级的重要原因.调查区域内BSi的沉积通量显著高于沉积物-海水界面SiO;-Si的释放通量,说明沉积物-海水界面以BSi的沉积为主,长江口及邻近海域是BSi的汇.

Biogenic silica in surface sediments of Yangtze River estuary and adjacent waters were measured to analyze the distribution of biogenic silica and preservation and distribution of biological silicon effects.The results showed that：the waters within the scope of the investigation and the content of biogenic silica in surface sediments range from 0.14％-0.70％,with an average of 0.41％.The clay minerals and silt sediments are enriched with more biogenic silica.The value of biogenic silica in sediment has a close relationship with the specific surface area.The biogenic silica（％） distribution characteristics had a similar contribution with TOC,TN in the surface sediments of the Yangtze River Estuary and adjacent seas.The biogenic silica（％） in the surface sediments is diluted by the biogenic silica（％） in the suspended matters.The biogenic silica deposition flux is significantly higher than the SiO32--Si flux,and the Yangtze River Estuary and adjacent waters may be the sink of biogenic silica.