长江口邻近海域沉积物中生物硅溶解行为研究

Study on the Dissolution Behavior of Biogenic Silica in the Changjiang Estuary Adjacent Sea

对长江口邻近海域进行调查,分析沉积物中生物硅的空间分布特征,探讨影响生物硅溶解以及保存的因素.结果表明,生物硅含量的平面分布具有近岸高于远海的分布趋势,陆源输入、沉积速率以及水动力条件是影响生物硅在沉积物中埋藏的主要因素.生物硅溶解速率常数随空间以及深度无明显变化规律,间隙水中硅酸盐相对于生物硅溶解度的不饱和程度、有机外壳对生物硅的包裹以及间隙水中Al离子浓度等因素会影响生物硅的溶解进而会影响其在沉积物中的保存和间隙水中硅酸盐浓度的变化.

Spatial distribution of biogenic silica （BSi） and factors influencing BSi preservation and dissolution in sediments were discussed based on the investigation in the Changjiang Estuary adjacent sea. The results showed that the contents of BSi were higher in nearshore sediments than those in offshore sediments. Terrestrial input, sediment accumulation rate and hydrodynamic conditions were the dominant factors affecting BSi preservation in sediments. BSi dissolution rate constant showed no obvious change with stations and sediment depth. BSi dissolution mainly depended on the following factors including undersaturation of silicie acid in pore water compared with BSi solubility, organic coating in BSi surface and aluminum concentration in pore water. And these factors can influence BSi preservation and the build-up of silicic acid in sediments.