Ocean Water

Chapter 20

Properties of Ocean Water• Dissolved Gases: gases can enter the ocean

from streams, volcanoes, organisms, and the atmosphere.

• Gases dissolve more rapidly in cold water than in warm water.

• The oceans are a “carbon sink.”

Properties of Ocean Water• Dissolved Solids: Ocean water is 96.5% pure

water (H20). 3.5% are dissolved solids called sea salts.

• Most common solids (85%) are the salt halite made up of sodium and chloride ions.

• Most of the sea salts come from chemical weathering of rocks on land.

Salts in the Ocean

Salinity of Ocean Water• Salinity: a measure of the amount of

dissolved salts in a given amount of liquid.

• Temperature affects salinity conditions. Warm/Tropical regions have higher rates of evaporation therefore have a higher concentration of salinity (meaning more salts).

Temperature of Ocean Water• Pack Ice: a floating layer of sea ice that

completely covers an area of the ocean surface. Ocean water freezes at about -1.9 C.

• Thermocline: a layer in a body of water in which water temperature drops with increased depth faster than it does in other layers.

Temperature of Ocean Water

Density of Ocean Water• Density: the ratio of the mass of a substance

to the volume of the substance.

• Ocean water becomes denser as it becomes colder and less dense as it becomes warmer. The densest ocean water is found at the polar regions causing it to sink.

Color of Ocean Water

• Water absorbs most of the wavelengths or colors of visible light. Only blue wavelengths tend to be reflected causing the ocean waters to appear blue.

Life in the Oceans• Marine organisms depend on 2 major factors

for their survival: essential nutrients available in ocean water and sunlight.

• Marine organisms help maintain the chemical balance of ocean water. They do this by removing nutrients and gases from the water while returning others to the ocean.

Upwelling• Upwelling: the movement of deep, cold, and

nutrient-rich water to the surface. Upwelling is caused by offshore movement of surface water.

Life in the Oceans• Most marine organisms live in the upper

100m of water.

• Plankton: the mass of mostly microscopic organisms that float or drift freely in the waters of aquatic environments. They live within the sunlit zone and form the base of most food webs in the ocean.

Life in the Oceans• Nekton: all organisms

that swim actively in open water, independent of currents.

• Benthos: organisms that live at the bottom of oceans or bodies of fresh water.

Ocean Environments• Benthic Zone: the bottom region of oceans

and bodies of fresh water.

• Pelagic Zone: the region of an ocean or body of fresh water above the benthic zone.

Ocean Environments