Discover the Wonders of Our Earth and the forces and life forms that shape our world with the Physical Geography Series. All water, even rainwater contains dissolved chemicals which scientists call "Salts. " These salts eventually wash down into rivers and streams and eventually find their way into oceans and seas. Subjects covered include: The origin of the sea. The sources of salt. The components of sea water. The salinity of the sea and it's variability. How sea life affects sea waters composition.