4. Why do diatoms need to stay on the surface of the water? (4 points)

Diatoms have a higher density than water. They can therefore not reach the water surface by buoyancy. ... Then they remain in the water body (tychoplankton) for a period of time and can also be transported to the surface.

Diatoms have a higher density than water.

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.