1. Ocean Water and Ocean Life
Chapter 15
Ocean Water and Ocean Life

2. The Composition of Seawater
Section 15.1
The Composition of Seawater

3. The Composition of Seawater
Salinity – is the total amount of solid material dissolved in water.
Because the proportion of dissolved substances in seawater is such a small number, oceanographers typically express salinity in parts per thousands.
Most of the salt in seawater is sodium chloride, common table salt.

4. The Composition of Seawater
Sources of Sea Salt
Chemical weathering of rocks on the continents is one source of elements found in seawater.
The second major source of elements found in seawater is from Earth’s interior.
Volcanic eruptions emitted water vapor and elements – chlorine, bromine, sulfur and boron.

5. Salts in Seawater

6. The proportion of dissolved substances in seawater is usually expressed in
Parts per hundred.
Parts per thousand.
Parts per ten thousand.
Parts per million.

7. Which of the following is a source of dissolved substances in the ocean?
Chemical weathering of rocks
Evaporation of water from the seas and ocean
Excretions from marine organisms
Melting icebergs and sea ice

8. The Composition of Seawater
Salinity
Processes Affecting Salinity
Processes that decrease salinity:
Precipitation
Sea ice melting
Icebergs melting
Runoff from land

9. The Composition of Seawater
Salinity
Processes Affecting Salinity
Processes that increase salinity:
Evaporation
Formation of sea ice

10. Natural Processes Affecting Salinity

11. Which does NOT decrease salinity?
Precipitation
Runoff
Evaporation
Ice melting

12. The Composition of Seawater
Ocean Temperature Variation
The ocean’s surface water temperature varies with the amount of solar radiation received, which is primarily a function of latitude.
Temperature Variation with Depth
The thermocline is the layer of ocean water between about 300 meters and 1000 meters where there is a rapid change of temperature with depth.
The thermocline is a very important structure because it creates a barrier to marine life.

13. Variations in Ocean Surface Temperature

14. Variations in Ocean Water Temperature

15. The Composition of Seawater
Ocean Density Variation
Density is defined as mass per unit volume. It can be thought of as a measure of how heavy something is for its size.
Factors Affecting Seawater Density
Seawater density is influenced by two main factors: salinity and temperature.

16. The Composition of Seawater
Ocean Density Variation
Density Variation with Depth
The pycnocline is the layer of ocean water between about 300 meters and 1000 meters where there is a rapid change of density with depth.

17. Variation in Ocean Water Density

18. Differing amounts of solar radiation across Earth’s latitude affect the ocean’s
Salinity in the thermocline.
Density at the surface.
Temperature at the surface.
Density in the thermocline.

19. Which of the following occurs when the ocean’s salinity increases?
Density increases
Density decreases
Temperature increases
Temperatures decreases

20. Which of the following occurs when temperature decreases?
Density decreases
Density increases
Salinity increases
Nothing happens

21. The layer of ocean water between 300 meters and 1000 meters where there is a rapid change in density.
Thermocline
Transition zone
Pycnocline
Deep zone

22. The Composition of Seawater
Ocean Layering
Oceanographers generally recognize a three-layered structure in most parts of the open ocean: a shallow surface mixed zone, a transition zone, and a deep zone.
Does not exist in high latitudes because there is no rapid change in temp or density.
Surface Zone
Shallow (300 to 450 meters)
Zone of mixing
Sun-warmed zone

23. The Composition of Seawater
Ocean Layering
2. Transition Zone
Between surface layer and deep zone
Thermocline and pycnocline
3. Deep Zone
Sunlight never reaches this zone.
Temperatures are just a few degrees above freezing.
Constant high-density water

24. Ocean Zones

25. Which of these is NOT one of the three layers of the ocean?
Photic zone
Surface zone
Transition zone
Deep zone

26. Where would you not find this three-layered structure of the open ocean?
High latitudes
Low latitudes
Deep ocean zone
Intertidal zone