Silicon, the second most abundant element in the earth’s crust, plays a vital importance role in nutrients circulation, marine productivity and the environment changing deduction. In our study, dissolved silicate (DSi) in water column, biogenic silica (BSi) in suspended particle matter (SPM) and surface sediments and relevant physical chemical parameters were measured in the Yangtze estuary and its adjacent area in August, 2013. Results showed that the Yangtze River input makes a major contribution to the concentrations of DSi and BSi. However, high turbidity and low biomass causes a very low percentage composition of BSi in SPM in the estuarine maximum turbidity zone. Vertically, concentrations of DSi and BSi in bottom water and surface water were higher than that in middle water because of the forceful resuspension process and riverine contribution respectively. Surface sediments in the area of the Hangzhou Bay and Zhejiang-Fujian coastal area contented more BSi than the others. Finer size sediments with higher specific surface area can absorb more organic matter, contributing to this phenomenon. Besides, differences of extreme value point positions between different water layers were caused by the hydrodynamic force of the Yangtze River diluted water.
Key words: dissolved silicate, biogenic silica, biogeochemical cycles, China East Sea
