Earth Science

Water on Earth

Seawater Chemistry

Study Tip
Both the salinity and the density of water are responsible for the currents in the deep ocean.

Mineral Composition of Oceanwater

  • Because H₂O is a polar molecule, it has the ability to dissolve many different substances.
Study Tip
Both the salinity and the density of water are responsible for the currents in the deep ocean.

Salinity

  • The salt in seawater comes from ions that water picks up as it flows over rocks and soil.
  • The salinity, or the salt content, varies from location to location.
  • The salinity is higher if there is a lot of evaporation and little circulation of water.

Water Density

  • Water density increases if:
  • Salinity or pressure increases
  • Pressure decreases
  • Differences in water density are responsible for deep ocean currents.
diagram displays concentrations of minerals
The diagram above displays the concentrations
of minerals inside the ocean’s waters.
Concept Check
  • In general, what kinds of minerals are present in seawater?
  • What is salinity? When will the salinity rise or fall?
  • How does the density of water change? What does the density affect?