Why is transparency of water important

The maximum visible depth indicates the transparency level of the water called the Secchi Depth. A demonstration of its use can be found in the video below starting at mins. There also exist some oceanographic equipments radiometers but as they are very expensive, they are not adequate for a citizen science project.

For a quick impression please view the video below in which experts Marcel Wernand and Oliver Zielinski provide a good insight in the concepts of water clarity. In lakes this means how deep sunlight penetrates through the water. Plants and algae need sunlight to grow, so they are only able to grow in areas of lakes where the sun penetrates.

The top section of the lake that sunlight penetrates is called the Euphotic zone. The area around the edge of the lake that is shallow enough for plants to receive light is called the littoral zone.

The area of the lake that is too deep for plants to grow is called the limnetic zone Figure 1. Water transparency depends on the amount of particles in the water. The main properties of water are its polarity, cohesion, adhesion, surface tension, high specific heat, and evaporative cooling.

A water molecule is slightly charged on both ends. Pure ice is transparent. Some refraction occurs as light passes through it, and red wavelengths are absorbed after a fair distance, so thick ice looks blue. But for the more part, thin sections are very transparent. To be transparent means to share your thoughts and opinions honestly and respectfully. Transparency is an approach to communicating and forming relationships that emphasize being direct with people in your workplace.

Objects made from transparent materials, such as glass and clear plastic, are common. Transparency of the water determines how far light will penetrate into the water. The more transparent the water, the deeper the microscopic plants that are the basis of the food chain can occur. Turbidity refers to the cloudiness of water and it reduces transparency. Turbidity can be caused by microscopic animals and plants, eroded soil and suspended sediments, chemicals, and even physical effects such as wind riffling the surface of the water.

Note: it may be difficult to do this test where the river current is fast or the depth is too shallow. A Secchi disk sek-ki is a round, black and white disk that is 6 to 8 inches in diameter. It is weighted and attached to a rope that has been marked in centimeters and meters. The disk is lowered into the water until it disappears from sight. It is then slowly raised so that it is just barely visible. The students will make Secchi disks in class.

Have the items listed on the Student Experiment sheet available and build the Secchi disks as a class or team activity. Why is transparency of the water important to plants and animals? What might be in the water that reduces transparency? The clearer the appearance of the water the more transparent it usually is, and the more light is available for water plants to use to make food.

The small animals are then eaten by larger animals. This is a simple food chain. Phytoplankton are the basis of many aquatic food chains that often include people.