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Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor. Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms. Siliceous oozes are largely composed of the silica based skeletons of microscopic marine organisms such as diatoms and radiolarians. Other components of siliceous oozes near continental margins may include terrestrially derived silica particles and sponge spicules. Siliceous oozes are composed of skeletons made from opal silica SiO2·nH2O, as opposed to calcareous oozes, which are made from skeletons of calcium carbonate (CaCO3·nH2O) organisms (i.e. coccolithophores). Silica (Si) is a bioessential element and is efficiently recycled in the marine environment through the silica cycle. Distance from land masses, water depth and ocean fertility are all factors that affect the opal silica content in seawater and the presence of siliceous oozes. Siliceous marine organisms, such as diatoms and radiolarians, use silica to form skeletons through a process known as biomineralization. Diatoms and radiolarians have evolved to uptake silica in the form of silicic acid, Si(OH)4. Once an organism has sequestered Si(OH)4 molecules in its cytoplasm, the molecules are transported to silica deposition vesicles where they are transformed into opal silica (B-SiO2). Diatoms and radiolarians have specialized proteins called silicon transporters that prevent mineralization during the sequestration and transportation of silicic acid within the organism. The chemical formula for biological uptake of silicic acid is: H4SiO4(aq) SiO2*nH2O(s) + (2-n)H2O(l) The opal silica saturation state increases with depth in the ocean due to dissolution of sinking opal particles produced in surface ocean waters, but still remains low enough that the reaction to form biogenic opal silica remains thermodynamically unfavorable.

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Biogenic silica

Biogenic silica (bSi), also referred to as opal, biogenic opal, or amorphous opaline silica, forms one of the most widespread biogenic minerals. For example, microscopic particles of silica called phytoliths can be found in grasses and other plants. Silica is an amorphous metal oxide formed by complex inorganic polymerization processes. This is opposed to the other major biogenic minerals, comprising carbonate and phosphate, which occur in nature as crystalline iono-covalent solids (e.g.

Marine microorganisms

Marine microorganisms are defined by their habitat as microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism (or microbe) is any microscopic living organism or virus, that is too small to see with the unaided human eye without magnification. Microorganisms are very diverse. They can be single-celled or multicellular and include bacteria, archaea, viruses and most protozoa, as well as some fungi, algae, and animals, such as rotifers and copepods.

Siliceous ooze

Silica Biomineralization: Evolution and Impact on Global Climate

Explores silica biomineralization in diatoms, radiolarians, and sponges, discussing its impact on global climate and the pH-dependence of silicon biomineralization.

Silica Biomineralization: Diatoms, Radiolarians, Sponges

Delves into silica biomineralization in diatoms, radiolarians, and sponges, exploring their origin, distribution, and impact on the ocean's silica cycle.

Biomineralization: Principles and Concepts

Covers the principles and concepts of biomineralization, including the types of biominerals, induced vs. controlled biomineralization, and its impact on the biosphere.