Ocean Water & Ocean Life

Unit 5 Chapter 15

Chapter 15.1 The Composition of Seawater

Seawater is approximately 96.5% water and 3.5% dissolved substances.

Salinity: total amount of solid material dissolved in water.

Expressed in parts per thousand (ppt)

Seawater is on average 35ppt

Where does the salt come from?

● Chemical weathering of rocks washed out to the ocean

● Material from volcanoes-sulfur dioxide and chlorine

● Precipitation

● Icebergs and sea ice melting

● Evaporation

Decreases of salinity:

Increases of salinity:

● runoff from land