percent of the earth's surface is water. The continuous movement of water
between the earth and the atmosphere has a significant relationship to all
life on the planet.
Because of its
capacity to dissolve many different substances, pure water rarely occurs
in nature. Carbon dioxide and other gases, as well as traces of organic
and inorganic material are all absorbed in rain and snow. Radioactive
particles and air born pollutants are also absorbed in the process of
condensation and precipitation.
ground water continue the process of dissolving and carrying pollutants in
the form of domestic sewage, agricultural chemicals and industrial waste.