Biogenic silica in marine sediments

Biogenic silica, in the form of opal, makes up an important part of marine sediments, particularly in the southern and eastern equatorial oceans (Figure 15). These deposits are formed primarily from tests of diatoms that lived in the surface oceans. More than half of the opal formed in the... 

Dixit S., Van Cappellen P., and van Bennekom A. J. (2001) Process controUing solubihty of biogenic silica and pore water build-up of sihcic acid in marine sediments. Mar. Chem. 73, 333-352. 

Dixit, S., P. Van CappeUen and A.J. van Bermekom (2001) Process controUing solubility of biogenic silica and porewater build-up of silicic add in marine sediments. Mar. Ghent. 73, 333-52. 

Romero O, Hebbeln D (2003) Biogenic silica and diatom thanatocoenosis in surface sediments below the Pern-Chile Curent Controlling mechanisms and relationship with productivity of surface waters. Max Micropaleontol 48(l-2) 71-90 Ruttenberg K (1992) Development of a sequential extraction method for different forms of phosphorus in marine sediments. Limnol Oceanogr 37(7) 1460-1482 Sabine CL, Mackenzie FT (1991) Oceanic sinks for anthropogenic CO2. Science 305(5682) 367-371... 

Marine processes. Sea water reacts with ocean-bed sediments containing volcanic ash, or biogenic silica from Radiolarians, to form zeolites. This process is common in deep-sea sediments and phillipsite makes up 80% of the sediment in the Indian and Pacific Oceans. Clinoptilolite is abundant in Atlantic sediments and both phillipsite and clinoptilolite are found in manganese nodules on the ocean beds. 

To measure the biogenic silica content of marine sediments, hot (85°C) alkaline solutions are used to dissolve biogenic silica over a period of 5-6 hours. The silicate concentration in the leaching solution is measured colorimetrically on a spectrophotometer... 

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