The silicon balance in Jiaozhou Bay, North China

A number of sampling trips in Jiaozhou Bay and major rivers emptied into the bay were made between 2001 and 2004. The concentrations of silicic acid (Si(OH)4) and particulate biogenic silica (PBSi) were higher in the north than in the south and higher in the fall than in the summer and the spring. The large amount of terrigenous material introduced into the bay dilute BSi content, and its content was about 1% in the bay bottom sediment. A broad-brush silicon budget based on the concentration in water and bottom sediment, sediment accumulation rate, phytoplankton uptake and regeneration in the water column and bottom sediment was established for Jiaozhou Bay. The model shows that the silicic acid is largely supplied from the Yellow Sea, with lesser amount from riverine inflow and wastewater discharge from the metropolitan area. The BSi burial efficiency in the bottom sediment was estimated to be 49%. Silicic acid regeneration in water columns and sediment appear to be the key process that keeps diatoms as the dominant species in Jiaozhou Bay.