1. Ocean Water
Chapter 20

2. Properties of Ocean Water
Dissolved gases
Primarily N2, O2, CO2
Gases enter from rivers, underwater volcanic eruptions, released by organisms, and mostly from the atmosphere.
Colder water dissolves gases more readily (this is why your soda does not go flat as quickly when kept in the refrigerator)

3. Dissolved Solids
Most abundant are: chlorine, sodium, magnesium, sulfur, calcium, potassium (salts)
Come from volcanic eruptions, chemical weathering of rock on land, chemical reactions between sea water and sea-floor rock.
As water evaporates, minerals and salts are left behind.
Salinity is measure of amount of dissolved salts and other solids in a liquid.
Salinity is affected by precipitation (reduces salinity by adding fresh water), evaporation and freezing (increases salinity by removing only water molecules).
Examples: Global Ocean average salinity is 34.7%. Red Sea more than 40% salinity due to hot, dry climate causing high levels of evaporation.

4. Temperature Varies depending on depth and location.
Surface water (100 to 300m) heated by solar radiation
Decreases at higher latitudes (polar water is cooler -1.9˚C than tropical water 30˚C+)
Thermocline
Area of water that
separates warm
surface water and
very cold deep water
Deep Water
Usually about 2 ˚C
Holds more dissolved
gases than warmer,
shallow water

5. Mass per unit volume (stuff in a space)
Density
Mass per unit volume (stuff in a space)
Density of pure water = 1g/cm3
Affected by:
salinity – increase in dissolved solids increases mass of water increasing its density. Ocean water density ranges from g/cm3 and g/cm3
Temperature – colder water is more dense than warmer water. Most dense water is found in polar regions.
Denser water sinks, less dense water rises

6. Color
Water color is determined by the way it absorbs or reflects sunlight.
White light contains all visible wavelengths (ROYGBIV)
Water tends to absorb most of the wavelengths. Only blue wavelengths are reflected.
Phytoplankton absorb red and blue light and reflect green. Therefore, large populations of phytoplankton affect the shade of blue of the ocean.

7. Life in the Oceans Life depends on essential nutrients and sunlight
Marine organisms help maintain the chemical balance of the ocean water by removing some nutrients and gases while returning others.
Example: photosynthetic marine plants absorb carbon dioxide from ocean water and release oxygen.
Upwelling – the movement of deep, cold, nutrient rich water to the surface due to density changes

8. Marine Food Webs
Most marine organisms live within the upper 100m of water.
Plankton – free floating microscopic
Phytoplankton - photosynthetic
Zooplankton – animal-like/non-photosynthetic
Nekton – swimmers
Benthos – bottom
dwellers
Distribution of marine
life depends on amount
of sunlight, water
temperature, and water
pressure

9. Ocean Environments
Two basic environments: benthic zone & pelagic zone

10. Ocean Resources Freshwater is available through desalination
Mineral and Energy Resources include:
Petroleum – drilled from beneath the sea floor
Nodules – sources of iron, copper, nickel, cobalt, phosphates.
Food
Fishing
Aquaculture

11. Ocean Water Pollution
Oceans have been used as dumping grounds for wastes including garbage, sewage, and nuclear waste
Increased human world-wide population and increased use of toxic substances have reduced the ocean’s ability to absorb & renew itself.
Pollution has resulted in destroyed clam and oyster beds, sea birds and marine mammals become tangled in trash, and beaches have been closed because of sewage and oil spills.
Traces of mercury , DDT (insecticide), and lead (from gasoline) are so high in some areas that fish are unsafe for human consumption.

14. North Pacific Garbage Patch