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MODEL : APAL – SCD
The Secchi disk originated with Fr. Pietro Angelo Secchi, an astrophysicist, who was requested to measure transparency in the Mediterranean Sea. Since April of 1865, Various sizes of disks have been used until now, but the most frequently used disk is an 8 inch diameter secchi disk.
The greatest value of the Secchi disc measurements occurs when each lake compares its own readings from week to week, month to month and season to season. No comparisons between lakes should be made unless similarities in measurements are followed vigorously. Several factors are involved, such as the eyesight of the viewer, the time of day the readings are taken (midday- between 10 and 12 is preferred), the reflectance of the disc, the color of the water, clay particles or other materials suspended in the water, etc.
Some of the reports for any one season may show an increased water transparency depth after the first week of spring. This may be due to:
1. Reduced nutrient input from the watershed.
2. Increased grazing of algae by zooplankton.
3. Reduced soil erosion into the lake.
Ideal for use in laboratory assignments dealing with water clarity. Perfect for any type of water, this 20 cm dia. limnological disc is constructed of heavy-duty ABS plastic with black and white quadrants.
Includes measuring tape.
