OCEAN WATER CHEMISTRY

I. The Salty OceanA. Salinity

1. On average, one kilogram of ocean water contains about 35 grams of salts. That is 35 parts per thousand.

2. Total amt of dissolved salts in a sample of water is the salinity of that sample.

WHAT IS SALINITY?

3. Table salt (sodium chloride) is present in the ocean.

4. Chloride and sodium make up almost 86% of ions in ocean water.

5. Ocean water also contains smaller amts of magnesium, calcium and other substances.

6. p. 373

B. Variations in Salinity1. Most parts of the ocean’s salinity is 34 and

37 parts per thousand.2. Near the surface, rain, snow, and melting

ice add fresh water which lowers the salinity.

3. Salinity is also lower near the mouths of large rivers such as the Amazon or Mississippi. These rivers empty large amts of fresh water into the ocean.

Teach TimeTell your neighbor where the ocean water has

less salinity and EXPLAIN WHY. (Must be at least two places).

4. In hot and dry climate, evaporation causes salinity to be higher. Ex: Dead Sea

5. Salinity is also higher near the poles where the surface water freezes into ice, and the salt is left behind.

Teach TimeExplain why the ocean has a greater salinity in

a hot and dry region.

Explain why the ocean has a greater salinity near the poles.

C. Effects of Salinity1. Ocean water does not freeze as quickly as

fresh water, because salt acts as an antifreeze.

2. Saltwater has higher density than fresh water.

3. Saltwater has a higher mass and buoyancy than fresh water. Why?

Salt Water

II. Other Ocean PropertiesA. Temp of ocean water drops as you get

deeper, and as you travel away from the equator towards the poles.

B. Carbon Dioxide is 60% more plentiful in the ocean than in air, b/c algae, corals, etc… need it.

C. Oxygen is scarcer in seawater than in air. It’s most plentiful near the surface.

WHY DOES THE OCEAN WATER NOT FREEZE AS QUICKLY AS FRESH WATER?

III. Changes with DepthA. Decreasing Temp.

1. surface zone- warmest2. transition zone- temperature drops very quickly.3. deep zone- coldest

B. Increasing pressure- pressure increases continuously as you get deeper in ocean.

C. Cold waters contain more oxygen than warm.

D. Why does warm water stay at the surface?E. A vertical section of the ocean is called the water column.Pg. 376

Teach TimeTeach your neighbor:

What happens to the temperature of the ocean as you get deeper? Why?

What happens to the pressure of the ocean as you get deeper? Why?

Benthos, Nekton, Plankton