Thursday, September 10, 2009
Freshwater can be defined as water with less than 0.5 parts per thousand of dissolved salts. (Seawater or Brine has more than 50 parts per thousand)
The ultimate source of fresh water is rain and snow.
Freshwater systems are the rivers, streams, lakes, ponds, groundwater, cave water, springs, floodplains, and wetlands (bogs, marshes, and swamps)
Freshwater provides water for drinking, sanitation, agriculture, transport, electricity generation and recreation. It also creates habitats for a diverse range of animals and plants.
We cannot live without freshwater.
Water is continually moving around, through, and above the Earth as water vapor, liquid water, and ice. Water is continually changing its form. The Earth is pretty much a "closed system," like a terrarium. That means that the Earth neither, as a whole, gains nor loses much matter, including water. Although some matter, such as meteors from outer space, are captured by Earth, very little of Earth's substances escape into outer space. This is certainly true about water. This means that the same water that existed on Earth millions of years ago is still here. Thanks to the water cycle. The same water is continually being recycled all around the globe. It is entirely possible that the water you drank for lunch was once used by Mama Alosaurus to give her baby a bath.