Secchi Disk

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Secchi disk

[′sek·ē ‚disk]
An opaque white disk used to measure the transparency or clarity of seawater by lowering the disk into the water horizontally and noting the greatest depth at which it can be visually detected.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Secchi Disk


an instrument for measuring water transparency in a body of water. A white disk 30 cm in diameter, it is held horizontally and lowered into the water on a rope until it is no longer visible. The depth, in meters, at which it ceases to be visible is taken as a measure of the water transparency. The disk is named after A. Secchi, who measured the transparency of sea water by this method in 1865.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Along with numbers of black sea bass at each site, abiotic factors were recorded, including water temperature (degrees Celsius), dissolved oxygen (milligrams per liter), salinity, Secchi disk depth (centimeters), and water depth (meters).
The abiotic factors used in the GLMs were water temperature, dissolved oxygen, salinity, and Secchi disk depth because analyses of variance determined that these factors varied between sites and months.
The index for chlorophyll-a, Secchi disk depth, and total phosphorus of [TSI.sub.M] along with the trophic levels of the studied lake are presented in Table 6.
The average Secchi disk depth in Lake James is about 4.0 m and euphoric depth hardly exceeded 12 m, meaning no light at 30 m and thus phytoplankton productivity was limited by the lack of light at this depth.
It is a spreadsheet program that uses regionally calibrated lake-response functions and basic, user-defined watershed and lake characteristics to estimate in-lake P, N, and chl a concentrations, and Secchi disk depth. Limitations of the simplistic watershed loading features were addressed by Mankin et al.
Secchi disk depth (water column transparency) improved 340 percent.