The turbidity test measures the cloudiness of water. If the water is
cloudy due to suspended sediment, sunlight is blocked, and pond
plants do not grow well. This can be harmful, because pond plants
are needed as food for other living things in the pond. A secchi disk
provides an easy way to measure turbidity (Figure 15.9). The disk
is lowered into the water until the black and white panels are no
longer visible to a person looking into the water. The rope holding
the disk is marked at meter and half-meter intervals to measure
the depth of the disk when it disappears from view underwater.
الرئيسية 
