[Study on the dissolution behavior of biogenic silica in the Changjiang Estuary adjacent sea].

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 silicic 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.