diatomaceous earth

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diatom (dīˈətŏmˌ, –tōmˌ), unicellular organism of the kingdom Protista, characterized by a silica shell of often intricate and beautiful sculpturing. Most diatoms exist singly, although some join to form colonies. They are usually yellowish or brownish, and are found in fresh- and saltwater, in moist soil, and on the moist surface of plants. They carry chlorophylls a and c and the carotenoid fucoxanthin contained in plastids. They reproduce asexually by cell division. Some 40,000 species (5,600 living species) are either bilaterally or radially symmetrical. For the most part they lack flagella. Although most diatoms are autotrophic, some heterotrophic or symbiotic species can be found in particular habitats. The living matter of each diatom is enclosed in a shell of silica that it secretes. These shells are marked by minute pores or depressions that allow the living organism access to its environment. As the principal constituent of plankton (see marine biology), diatoms are an important food source for fish and other aquatic animals, e.g., the baleen whales.

When aquatic diatoms die they drop to the bottom, and the shells, not being subject to decay, collect in the ooze and eventually form the material known as diatomaceous earth (sometimes called kieselguhr). When it occurs in a more compact form as a soft, chalky, light-weight rock, it is called diatomite. Deposits of diatomaceous material, formed underwater in past geologic time and now exposed above water, are found in all parts of the world. Diatomite is much used as an insulating material against both heat and sound, in making dynamite and other explosives, and for filters, abrasives, and similar products. Most of the earth's limestone has been deposited by diatoms, and much petroleum is of diatom origin.

Diatoms are classified in the phylum (division) Chrysophyta, class Bacillariophyceae.

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diatomaceous earth

[¦dī·ə·tə¦mā·shəs ′ərth]
A yellow, white, or light-gray, siliceous, porous deposit made of the opaline shells of diatoms; used as a filter aid, paint filler, adsorbent, abrasive, and thermal insulator. Also known as kieselguhr; tripolite.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

diatomite, diatomaceous earth, kieselguhr

A white or light gray, chalky, natural siliceous material; obtained by mining deposits of fossil remains of small marine life; used as an extender in paints, as an aggregate in lightweight concrete, as a waterproofing material in portland cement, as a filter for water, and as an abrasive.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Following is the basic protocol used for diatomaceous earth, followed by any modifications for other treatments.
The deposit of diatomaceous earth that was more intensely explored among all the Sesimbra region is located in Amieira, around 1km NNE of Alfarim (Fig.
Diatomaceous earth can be vermicomposted, even soaked in biofuel oil, in quantities of up to 30.12% (v/v) of the mixture with pre-compost of sewage sludge and plant residues, without visible physical damages to the Eisenia foetida earthworms.
The combined use of entomopathogenic fungi with diatomaceous earth is advocated not only to enhance the relative effectiveness of both substances (Lord 2001) but the dust formulation of the fungus ensures easy handling of the conidia, prolonged or unaffected conidial viability (Akbar et al.
Treatments were kaolin (Protesyl[R]) (Fertirico, Curitiba, PR, Brazil) (2, 4 and 8g [kg.sup.-1]), kaolin+neem [2g [kg.sup.-1] (5% neem oil)] (Fertirico, Curitiba, PR, Brazil); diatomaceous earth (DE) (KeepDry[R]) (Vet Quimica, Campinas, SP, Brazil) (1g [kg.sup.-1]) and control.
In the current study Protect-It[TM] (Hedley Technologies Inc, USA), and inert dust formulation containing 90% diatomaceous earth (DE) and 10% silica gel was tested for effectiveness to control T.
More than 400 tonnes of effluent diatomaceous earth sludge and paper dust waste from corrugated board manufacturing and printing processes at Smurfit Kappa Northampton is now being composted by Land Networks (Gainsborough) Ltd.
"Although the surface mc may rise to about 11%, application of Diatomaceous Earth (DEs) is effective in controlling mites in these circumstances.
The company notes that the system also eliminates the use of diatomaceous earth (DE) from beer production, removing the filtration and maintenance activities associated with diatomaceous earth systems.
It cleans and filters the oil without using chemicals or additives, nor is diatomaceous earth required.
Samples of the pool water and diatomaceous earth filter material from the swimming pool were collected and sent to the Minnesota Department of Health Laboratory for analysis.
Chrysanthemum-derived pesticides, diatomaceous earth and boric acid are sold in garden centers.