1. Ocean Composition

2. Salinity
Salinity – a measure of the amount of dissolved solids in a given amount of liquid
Measured as grams of dissolved solids per kilogram of water
1 kg of ocean water contains 35 g of dissolved solids

3. Where does all that salt come from?
Precipitation
Acid rain breaks down rocks  dissolved salts and minerals are carried away (runoff)  rain and dissolved salts and minerals are deposited in the ocean

4. Underwater Volcanoes Hydrothermal Vents
Result of seawater filtering down in the ocean crust where it meets the magma
Minerals in the crust begin to dissolve, adding to the salt content of the ocean
Underwater Volcanoes
Similar to the process with hydrothermal vents, during an underwater eruption, seawater reacts with hot rock and some minerals are dissolved into the ocean water

5. What affects salinity? Climate
Coastal water in places with hotter, drier climates has a higher salinity
Coastal water in cooler, more humid places has a lower salinity
More fresh water from streams and rivers run into the ocean in these areas
Glaciers melting add freshwater to the oceans
Heat INCREASES the evaporation rate. Evaporation removes water but leaves salts and other dissolved solids behind.

6. Water Movement Slower moving areas of water develop higher salinity
Example: bays, gulfs, seas, open ocean without currents moving running through them
Dead Sea = Very Salty – 337 PPT (33.7%)
Baltic Sea = Not Very Salty – 10 PPT (1%)

7. Salinity, Density, and Temperature
Salt makes seawater more dense than freshwater
Oceans with a higher salinity are going to have a higher density
Warmer water = lower density
Colder water = higher density
*Water that is cold and high in salt will sink to the bottom of the ocean floor due to its density*