the study of the biological, chemical, and physical features of inland aquatic ecosystems.
M O D U L E O N E properties of water
WHAT IS WATER?
... play audio ...
The water on the surface of Earth is found mainly in its oceans (97.25 percent) and polar ice caps and glaciers (2.05 percent), with the balance in freshwater lakes, rivers, and groundwater.
water composed of hydrogen and oxygen, liquid at room temperature in solid form ice freezing point, gas form - water vapour.
liquid state is denser than the solid state - unusual, ice floats.
The fact that ice floats on water is exceedingly important in the natural world, because the ice that forms on ponds and lakes in cold areas of the world acts as an insulating barrier that protects the aquatic life below. If ice were denser than liquid water, ice forming on a pond would sink, thereby exposing more water to the cold temperature. Thus, the pond would eventually freeze throughout, killing all the life-forms present.