Biogenic silica

Biogenic Silica

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Biogenic silica

Biogenic silica (BSi) is the equivalent to the terms opal

Opal

Opal is a mineraloid gel which is deposited at a relatively low temperature and may occur in the fissures of almost any kind of Rock , being most commonly found with limonite, sandstone, rhyolite, and basalt....
, biogenic opal, and amorphous opaline silica. BSi is essential to many plants and animals. Chemically, BSi is hydrated silica (SiO₂•nH₂O).

Diatom

Diatom

Diatoms are a major group of eukaryote algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as Colony in the shape of filaments or ribbons , fans , zigzags , or stellate colonies ....
s in both fresh and salt water extract silica from the water to use as a component of their cell walls.

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Encyclopedia

Biogenic silica (BSi) is the equivalent to the terms opal

Opal

Diatom

Holoplankton

Holoplankton are organisms that are planktonic for their entire life cycle. Examples of holoplankton include diatoms, radiolarians, dinoflagellates, foraminifera, amphipods, krill, copepods, and salps....
ic protozoa

Protozoa

Protozoan are microorganisms classified as unicellular eukaryotes. While there is no exact definition of the term "protozoan", most scientists use the word to refer to a unicellular heterotrophic protist, such as an amoeba or a ciliate....
(Radiolaria), some sponges, and some plants (leaf phytolith

Phytolith

A phytolith is a rigid microscopic body that occurs in many plants. The most common type of phytolith is the silica phytolith, also called opal phytolith....
s) use silicon as a structural material. Silicon

Silicon

Silicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. The atomic mass is 28.0855....
is known to be required by chicks and rats for growth and skeletal development. Silicon is in human connective tissue

Connective tissue

Connective tissue is a form of fibrous biological tissue.It is one of the four types of tissue in traditional classifications .Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content....
s, bone

Bone

Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
s, teeth, skin

Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
, eye

Eye

Eyes are Organ that detect light, and send signals along the optic nerve to the visual system and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system....
s, gland

Gland

A gland is an Organ in an animal's body that synthesizes a substance for release such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface ....
s and organs

Organ (anatomy)

In biology, an organ is a biological tissue that performs a specific function or group of functions. Usually there is a main tissue and sporadic tissues....
. It is a major constituent of collagen

Collagen

Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content....
which helps keep our skin elastic

Elasticity (physics)

In physics, elasticity is the physical property of a material when it deforms under stress , but returns to its original shape when the stress is removed....
, and it helps calcium

Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
in maintaining bone strength.

BSi is silica that originates from the production out of dissolved silica

Dissolved silica

Dissolved silica is the form of water soluble silica as silicon hydroxide , which can be measured by standard analyses . However, The term dissolved silica is different from the silicate occurring as silicate minerals, which is a class of minerals forming rings, sheets, chains, and tetrahedrons....
. BSi can either be accumulated "directly" in marine sediment

Pelagic sediments

Pelagic sediments, also known as marine sediments, are those that accumulate in the abyssal plain of the deep ocean, far away from terrestrial sources that provide terrigenous sediments; the latter are primarily limited to the continental shelf, and deposited by rivers....
s (via export) or be transferred back into dissolved silica in the water column.

Increasingly, isotope ratio

Isotopic signature

An isotopic signature is a ratio of stable or unstable isotopes of particular elements found in an investigated material. The atomic mass of different isotopes affect their chemical kinetics behavior, leading to natural isotope separation processes....
s of oxygen (O¹⁸:O¹⁶) and silicon (Si³⁰:Si²⁸) are analysed from BSi preserved in lake and marine sediments to derive records of past climate change

Climate change

Climate change is any long-term significant change in the expected patterns of average weather of a specific region over an appropriately significant period of time....
and nutrient cycling (De La Rocha, 2006; Leng and Barker, 2006). This is a particularly valuable approach considering the role of diatom

Diatom

Diatoms are a major group of eukaryote algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as Colony in the shape of filaments or ribbons , fans , zigzags , or stellate colonies ....
s in global carbon cycling. In addition, isotope analyses from BSi are useful for tracing past climate changes in regions such as in the Southern Ocean

Southern Ocean

The Southern Ocean, also known as the Great Southern Ocean, the Antarctic Ocean and the South Polar Ocean, comprises the southernmost waters of the World Ocean south of 60th parallel south latitude....
, where few biogenic carbonate

Carbonate

In chemistry, a carbonate is a salt or ester of carbonic acid....
s are preserved.

BSi production

The mean daily BSi rate strongly depends on the region:

Coastal upwelling: 46 mmol m^-2 d^-1
Sub-arctic
Arctic

The Arctic is the region around the Earth's North Pole, opposite the Antarctica region around the South Pole. The Arctic includes the Arctic Ocean and parts of Canada, Greenland , Russia, the United States , Iceland, Norway, Sweden and Finland....
Pacific]]: 18 mmol m^-2 d^-1
Southern Ocean: 3–38 mmol m^-2 d^-1
mid-ocean gyre
Gyre

A gyre is any manner of swirling vortex, particularly large-scale wind and ocean currents. Gyres are caused by the Coriolis effect; planetary vorticity along with horizontal and vertical friction which determine the circulation patterns from the wind curl ....
s: 0.2–1.6 mmol m^-2 d^-1

Likewise, the integrated annual BSi production strongly depends on the region:

Coastal upwelling: 3 ^. 10¹² mol yr^-1
Subarctic Pacific: 8 ^. 10¹² mol yr^-1
Southern Ocean: 17–37 ^. 10¹² mol yr^-1
mid-ocean gyres: 26 ^. 10¹² mol yr^-1

BSi production is controlled by:

Dissolved silica
Dissolved silica

Dissolved silica is the form of water soluble silica as silicon hydroxide , which can be measured by standard analyses . However, The term dissolved silica is different from the silicate occurring as silicate minerals, which is a class of minerals forming rings, sheets, chains, and tetrahedrons....
availability, however, half saturation constant Kµ for silicon-limited growth is lower than Ks for silicon uptake
Uptake

Uptake may refer to:*Diffusion , the acceptance or adoption of a new product or idea.*Diffusion , the movement of materials from an area of high water potential, to an area of low water potential....
.
Light availability: There is no direct light requirement; silicon uptake at 2x depth of photosynthesis
Photosynthesis

File:Seawifs global biosphere.jpgPhotosynthesis is a metabolic pathway that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight....
; silicon uptake continues at night but cells must be actively growing.
Micronutrient
Micronutrient

Micronutrients are nutrients needed for life in small quantities. The Microminerals or trace elements include at least iron, cobalt, chromium, copper, iodine, manganese, selenium, zinc and molybdenum....
availability.

BSi dissolution

BSi dissolution is controlled by:

Thermodynamics
Thermodynamics

In physics, thermodynamics is the study of the conversion of heat energy into different forms of energy ; different energy conversions into heat energy; and its relation to macroscopic variables such as temperature, pressure, and volume....
of solubility
Solubility

Solubility is often seen as a property of a substance; for instance the solubility of a solid substance usually refers to the concentration of the substance in a liquid that has reached equilibrium with the substance in solid phase ....
: Temperature (0 to 25 °C - 50x increase).
Sinking rate: Food web structure—grazers, fecal pellets, discarded feeding structures, Aggregation - rapid transport.
Bacteria
Bacteria

The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
l degradation
Degradation

Degradation may refer to;* Degradation , metal band from Chicago, IL USA* Biodegradation, the processes by which organic substances are broken down by living organisms...
of organic matrix (Bidle and Azam, 1999).

BSi preservation

BSi preservation is measured by:

Sedimentation rates, mainly sediment traps (Honjo);
Benthic
Benthic zone

The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers....
remineralization
Remineralisation

In biogeochemistry, remineralisation refers to the transformation of organic molecules to inorganic forms, typically mediated by biological activity....
rates ("recycling"), benthic flux chamber (Berelson);
BSi concentration in sediments, chemical leaching in alkaline solution
Solution

In chemistry, a solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is dissolved in another substance, known as a solvent....
, site specific, need to differentiate lithogenic
Lithogenic silica

Lithogenic silica comes from the Greek words lithos, which means rock, and genesis, which means coming from. LSi is silica that originates from terrestrial sources of rock and soil, i.e....
vs. biogenic Si, X-ray diffraction.

BSi preservation is controlled by:

Sedimentation rate;
Porewater dissolved silica concentration: saturation at 1.100 µmol/L;
Surface coatings: dissolved Al modifies solubility of deposited biogenic silica particles, dissolved silica can also precipitate with Al as clay
Clay

Clay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content, and which can be hardened when dried and/or fired....
or Al-Si coatings.