Post on 07-Jul-2015
transcript
Chapter 24-1
OCEANSEDU 653- Keri Adams
Why isn’t Ocean Water Pure?
Two main dissolved gases = N2 and O2.
CO2 (in large amounts)
Other atmospheric gases (in small amounts)
How do Gases Enter the Ocean?
The atmosphere (most O2 enters this way)
Underwater volcanoes
Marine organisms
Streams and rivers
Temperature and Dissolved Gases
Gases dissolve more readily in COLD water.
Water at the surface of the ocean in COLD regions dissolve larger amounts of gases than water in WARM tropical regions.
Gases can return to atmosphere from ocean (evaporation).
Carbon Sink
Ocean = 60X as much Carbon as atmosphere
CO2 trapped in ocean for years and years
Ocean is a carbon sink….b/c ability to dissolve and contain a lot of CO2
CO2 traps thermal energy, so ocean is important in climate regulation
Dissolved Solids
Ocean water = 96.5% pure water and 3.5% dissolved solids called sea salts
Dissolved solids made of 75 elements.
Ocean water mostly: Cl, Na, Mg, S, Ca, K
85% of solids is HALITE
Trace elements(in small amounts) Au, Zn, P
Sources of Dissolved Solids
Volcanic eruptions
Chemical weathering of rock on land
Chemical reactions b/t sea water and newly formed sea floor rocks
Salinity of Ocean H2O
Salinity – measure of the amount of dissolved salts and other solids in a given liquid
Measured by # grams of dissolved solids in 1,000 grams ocean water (parts per thousand or ‰)
Higher salinity = better conductivity
Factors that Affect Salinity
Precipitation = fresh water
Ocean water evaporates or freezes…only H2O molecules removed
Rate of evaporation higher than precipitation = salinity of surface water increases
Equatorial water = salinity lower
Salinity ranges 33‰ to 36 ‰, average 34.7 ‰
Temperature of Ocean Water
Varies with depth and location on the surface
Temperature range is affected by amount of solar energy and movement of water in the ocean
Surface Water
Heat is distributed downwards to 100-300 m (this zone is relatively constant and decreases slightly as depth increases).
Temperature of surface water decreases as latitude increases
Ocean water freezes at -1.9°C.
Pack ice – floating layer of sea ice completely covers an area of an ocean surface; ≤5 m thick; insulates water below it
Thermocline
Thermocline – layer in a body of water in which water temperature drops with increased depth faster than it does in other layers
Changing temperatures or shifting currents alter the depth of the thermocline or cause it to disappear
Deep Water
Density of cold, deep water controls slow movement of deep ocean currents
Cold, deep ocean water holds more dissolved gases than warm, shallow ocean water
Density of Ocean Water Density = mass/volume
Density of pure water = 1 g/cm3
Salinity and temperature affect density!
Density of ocean water = 1.020 – 1.029 g/cm3
Ocean water becomes denser as it gets colder and saltier
Densest ocean water = polar regions
Ocean Water Color
Determined by the way it absorbs or reflects sunlight
White light from sun has all visible wavelengths of EMS
All colors are absorbed by the water except, blue, it is reflected allowing the color blue to be seen
Why is Ocean Color Important?
Phytoplankton – microscopic plants in the ocean that provide food to many of the ocean’s organisms; absorb red and blue light; reflect green light
Presence of phytoplankton affect shade of blue of the ocean
Phytoplankton require nutrients; presence or absence of them indicate health of ocean
Citations Allison, M. A., & DeGaetano, A. T. (2010). Oceans. Holt McDougal Earth
Science (Student ed., ). Austin, TX: Holt McDougal, a division of Houghton Mifflin Harcourt Publishing Co..