Biogenic Silica In Sediments Of The Yellow Sea, East China Sea

Biogenic silica (BSi) is produced in the euphotic zone of the ocean by siliceous plankton such as diatoms. Due to the major role played by diatoms in the biological pump of CO2, biogenic silica may have a close coupling in the global carbon cycle. In addition, the accumulation of biogenic silica in the ocean floor can reflect the spatial and temporal distributions of marine productivity.Biogenic silica content in sediments of the Yellow and East China Seas was determined in September, 2002 and it came to the results that (1) the concentration of biogenic silica in sediments in the investigated area was less than 1% (2) The maximum of value biogenic silica usually lied between 0~1cm at each station, but the vertical profile was different from one station to another. The content of biogenic silica in the sediments had close relationship with the content of chlorophyll. Moreover, it was found that the content of BSi was also related to the fluxes of nutrients.Additionally, through the study, it declared that the distribution of biogenic silica in surface sediments were consistent with the distribution of salinity by determining the content of biogenic silica in surface sediments and silica acid in interstitial water in the Changjiang Estuary. The solubility of biogenic silica had been studied through batch experiments. The results indicated that the solubility of biogenic silica was affected by the biogenic silica, solid to solution ratio, temperature, pretreatment method. It shows that the larger the content of biogenic silica was, the larger the dissolution rate of silica acid was in the beginning of incubation experiments. But finaly, the dissolution rate was mainly affected by the content of aluminium in the solution. It is obvious that the the distribution of silica acid in interstitial water were affected by the contents of biogenic silica and aluminium, and aquiferous proportion as well.