1. Physical Characteristics of the Ocean Environment
SOL 5.6

2. OBJECTIVES
TSW
Describe the variation in depths associated with ocean features (shelf, slope, rise, abyssal plain, and trench)
Explain the cause of salinity in ocean water
Compare and contrast various salinity levels of ocean water
Explain what causes currents and tides
Locate and describe the Gulf Stream
Describe how scientists have explored the oceans

3. VARIATIONS IN DEPTH

4. Why is ocean water salty?

5. SALINITY All water is made of hydrogen and oxygen.
Ocean water is not just pure water.
It has dissolved gases, like air, and dissolved solids, especially salt.
The salinity measures how much salt is present in water. (“Salinity = saltiness”)
Common salt (sodium chloride) is the main salt found in the ocean.

6. SALINITY
Different bodies of water can have different amounts of salt in solution (different salinities)
Ocean water is about 220 times saltier than fresh lake water.
Measure salinity by finding how much total salt is dissolved in 1,000 grams of ocean water (1 ppt)
On average, 35 grams of salt are dissolved in every 1,000 grams of ocean water (35 ppt)
The salinity of fresh water is usually less than 0.5 ppt (0.5 ppt – 17 ppt is called brackish)

7. How did the salt get into the ocean?

8. SALINITY
Most of the salt in the ocean was carried there by rivers. Rivers pick up pieces of rock, sediment, and soil as they flow. All rivers meet at an estuary, where the runoff containing mineral salts, is deposited into the ocean. Eventually, the salts dissolve into the ocean.
Evaporation is another reason. The sun’s heat causes some water to evaporate. Salts do not evaporate. Over time, the salts that remain increase the salinity of the ocean.
Some of the salt in the oceans comes from undersea volcanoes and hydrothermal vents.

9. Why does ocean salinity vary?

10. SALINITY The ocean’s salinity varies from place to place.
In hot tropical/warm, dry regions, ocean water evaporates and little precipitation can cause ocean water to have a high salinity.
In cold regions, salinity is lower because less evaporation takes place and melting ice and snow add fresh water. Areas of lower salinity also occur where freshwater rivers enter the ocean.

11. SALINITY Depth affects salinity, too.
Salt water has a greater density (“is heavier”) than fresh water.
Saltier water sinks deeper.
Therefore, salinity increases with ocean depth.

12. SALINITY
SOL 5.6 Video Clip – 2 mins

13. Physical Characteristics CHECKPOINT
What does salinity measure?
How much ocean water evaporates
How much salt is present in ocean water
How deep the ocean water is
How much pressure is applied

14. Physical Characteristics CHECKPOINT
What are two reasons that the ocean is saltwater?
No multiple choice...

15. Physical Characteristics CHECKPOINT
Explain why salinity increases as you go deeper in the ocean.
No multiple choice...

16. Physical Characteristics CHECKPOINT
How does most salt get into the ocean?
rainfall
rivers
animals
volcanoes

17. Physical Characteristics CHECKPOINT
What makes the ocean in hot tropical regions have a high salinity?
Melting polar ice caps
Wind patterns
High evaporation rate
None of the above

18. Physical Characteristics CHECKPOINT
BIG BUCKS BONUS:
Which type of ocean water would have the highest salinity?
Deep water in the tropics
Shallow water in the tropics
Deep water near the poles
Shallow water near the poles

19. Investigating the Ocean Environment - Salinity
Salty Sea
SOL 5.6 Lab

20. Salty Sea Salt Fresh water Large, clear plastic cups Food coloring
SOL 5.6 Lab
Salt
Fresh water
Large, clear plastic cups
Food coloring
Spoons
Potato slices
ocean water
Graduated cylinders
Hand lenses or microscope
Droppers
Clean microscope slides
Lab sheet (each)
One lab partner (jigsaw)

21. Salty Sea PARTNER 2 PARTNER 1 PROCEDURE A
SOL 5.6
PROCEDURE A
PARTNER 2
Mix 8 teaspoons of salt into the water of the other cup (salt water)
Hold the spoon directly over the salt water while PARTNER 1 pours the colored water very slowly into the spoon so that it slowly drips out into the salt water
Try to keep the spoon close to the salt water when pouring the colored water in order to reduce splashing and mixing of the waters
PARTNER 1
Fill 2 clear plastic cups less than half full with the same amount of fresh water
Mix a few drops of food coloring into one cup (fresh water)
Very slowly and gently lower a potato slice into the cup without stirring the water.

22. Salty Sea PARTNER 1 PARTNER 2 PROCEDURE B Get ½ cup of salt water
SOL 5.6
PROCEDURE B
PARTNER 1
Get ½ cup of salt water
Smell both samples and describe what you smell
Pour ¼ of freshwater into a graduated cylinder to determine the volume
Put a drop of saltwater on a clean microscope slide and observe it with a magnifying glass (or a microscope)
Fan the two drops of water until the water evaporates
PARTNER 2
Get ½ cup of freshwater
Smell both samples and describe what you smell
Pour ¼ cup of salt water into a graduated cylinder to determine the volume
Put a drop of freshwater on a clean microscope slide and observe it with a magnifying glass (or a microscope)
Fan the two drops of water until the water evaporates