Facts About Diatoms and their applications
Diatoms are microscopic single-celled photosynthetic organisms. Each one lives inside a protective silica test, most of which contain two halves that fit together very much similar to a shoebox and its lid. The fossil record indicates that diatoms have been on Earth since the Jurassic Period (180 million years ago), and at least 70,000 species of diatoms have been identified.
The tests of diatoms are exquisitely ornamented with holes, ribs, and radiating spines unique to individual species.
Diatoms live for a few days to as much as a week, can reproduce sexually or asexually, and occur individually or linked together into long communities. They are found in great abundance floating in the ocean and in certain freshwater lakes but can also be found in many diverse environments, such as on the undersides of polar ice, on the skins of whales, in soil, in thermal springs, and even on brick walls.
When marine diatoms die, their tests rain down and accumulate on the sea floor as siliceous ooze. Hardened deposits of siliceous ooze, called diatomaceous earth, can be as much as 900 meters thick. Diatomaceous earth consists of billions of minute silica tests and has many unusual properties such as :
- It is lightweight and has an inert chemical composition.
- It is resistant to high temperatures, and
- It has excellent filtering properties.
Due these properties, diatomaceous earth is used to produce a variety of common products such as filters, mild abrasives (in toothpaste, facial scrubs, matches, and household cleaning and polishing compounds) absorbents (for chemical spills, in cat litter, and as a soil conditioner) chemical carriers (in pharmaceuticals, paint, and even dynamite) Other products from diatomaceous earth include optical-quality glass (because of the pure silica content of diatoms) and space shuttle tiles (because they are lightweight and provide good insulation). Diatomaceous earth is also used as an additive in concrete, a filler in tires, an anticaking agent, a natural pesticide, and as building stone in the construction of houses.
Apart from this, each living diatom contains a tiny droplet of oil. When diatoms die, their tests containing droplets of oil accumulate on the sea floor and thus they are the beginnings of petroleum deposits.