The Water PlanetCh. 22
What is Oceanography?
the study of the Earth’s oceans using chemistry, biology, geology, and physics.
Oceans cover 70% of the Earth’s surface
The use of submarines in World War II advanced ocean research with the invention of SONAR.
Ocean
Research
22.1
H.M.S Challenger
1872 first large-scale ocean research project
Measured:TemperatureDepthTook water samplesObserved currents
World War II
Better ocean maps and charts
Instruments: Sonar Magnetic recorders
Modern Research (Technology)
Deep sea-corers take sediment samples
Sonar measures ocean depth
Deep sea cameras and lights, robotics, and advanced technology help explore the sea floor & take samples
buoys & satellites radio data back SST, sea level, & mov’mt
Think-Pair-Share:How do humans
effect the oceans?
List your ideas in your notes!!
Human EffectsOil spillsDeep sea mining
Magnesium (Mg) Table salt
PollutionDredging
Disturbs ocean floorGlobal warming
Melts ice caps, changes salinity & sea level
The density of water is greater than its solid form, ice
Special Properties of Water
22.2
Density
Density= mass ÷ volume (g/cm³)- it’s a ratio!
Density of fresh water= 1.0 g/cm³ (above freezing)
Density of ice= 0.92 g/cm³
Water expands as it freezes because of it’s shape! ICE FLOATS!!!
Aqueous Solutions
ocean is best example!
as salt increases, density increases
change water’s: pH density boiling & freezing points
Salinity and temperature are two characteristics of water masses that help scientists study oceans and their behavior.
Ocean Water
22.3
Composition of Seawater
Contains salts as dissolved ions
85% sodium chloride ions
more than 70 elements some elements, such as
calcium (Ca)--needed for marine life shells
Ions in Seawater
Chloride 55.04%
Sodium 30.61%
Sulfate 7.68%
Magnesium
3.69%
All others 2.98%
Salinity
measure of dissolved salts in water
units= parts per thousand (‰)
Ex: 1000 grams of seawater contains 35 grams of salt= 35 ‰
measured w/ hydrometer
Salinity
oceanographers calculate salinity by electrical conductivity of seawater The higher the salinity, the stronger the electrical
current
units= practical salinity units or psu
average seawater = 35 psu
LOW SALINITY AREAS HIGH SALINITY AREAS
near rivers where fresh water enters
high precipitation near equators
sea ice melts
hot, dry climates w/ high evaporation rates about 30º N & S
(deserts)
near poles as water freezes
Variations in Salinity
* SALINITY IS USUALLY AVERAGE (35‰) NEAR THE BOTTOM
High-5 & Share:What do you think the salinity
of the ocean is like at the Equator? Why?!
High-5 & Share:What do you think the salinity
of the ocean is like at the Poles? Why?!
At your seat…
Complete the bottom of p. 6 in
your INB.
Make a key for high or low salinity and
use 2 colored pencils. Ask for help
if you need it!
ENTER LEAVEunderwater
volcanoes
erosion from rocks
marine organisms decompose
marine organisms use minerals for life
precipitate out of solution into sediment at floor
Salt Enters & Leaves the Ocean
* Scientists believe the salinity of the ocean hasn’t changed in over 200 million years!
Temperature of the Ocean
heat from sun
temperature decreases w/ depth
Ocean divided into 3 temperature zones:1. Mixed Layer or
Epipelagic Zone2. Thermocline3. Deep zone
Epipelagic Zone or ‘Mixed Layer’
winds and currents mix heat evenly
most life lives here; only zone for plants
makes up 2% of ocean’s volume
can be 50-100m deep; in some spots 300m
temperature depends on latitude and season; poles and equator mixed layer temperature is constant
Most oxygen- b/c of atmosphere & organisms (photosynthesis) Oxygen decreases with depth
Creation of the Mixed Layer (surface)
Thermocline
Temperature decreases rapidly throughout this zone
Little to no light
Varies most at mid-latitudes, not much variation at poles or Equator
Page 8 INB:
Which one belongs to the poles? The Equator? The mid-latitudes?• Talk with your neighbors!!!
Deep Zone
No sunlight reaches seafloor- DARK!
Very little oxygen & life
Polar water masses are found at bottom because they are denser than other water and move around globe
Seafloor temperature @ bottom = ~ 2° C
Water Mass
Characterized based on where they originate
Body of water characterized by: Salinity temperature
What do YOU think??
How do water
masses layer in the
ocean? Why?
Life forms range from microscopic organisms to the largest known animal, the blue whale.
Ocean Life
22.4
Scientists estimate that the oceans harbor as many as 10 million species!
Photosynthesis in the Ocean
takes place within mixed layer
Phytoplankton: microscopic single celled protists that float freely within ocean waters take CO2 out of water and replace with oxygen basis of food chain in ocean Diatoms are examples with silica shells; deposited on
seafloor when they die
Blooms- abundant phytoplankton populations; change color of seawater to green, yellow, or brown Visible from space; scientists use to locate groups of life forms
Phytoplankton
Blooms are visible from space and help scientists track life forms.
Marine Animal Life
Zooplankton: microscopic animals that eat phytoplankton or smaller zooplankton other animals eat zooplankton can be larvae of larger animals s.a. squid, crab,
jellyfish moderate salinity by absorbing ions to make
shells; back into water when they die promote nutrient circulation as waste falls to
bottom
Coral: tiny sea creatures that form reefs lime from ocean creates shells; when they die new
ones grow on old ones prevent beach erosion b/c they stop waves along
coasts provide nutrients and shelter for larger organisms
Marine Animal Life (cont.)
Nektons: free-swimming organisms include fish, whales, jellyfish survival depends on temperature, salinity, and nutrient
circulation important food supply for other nektons and humans overfishing, pollution, and trawling destroy populations
& ecosystems
Deep Ocean Lifeno photosynthesis means
no oxygen so CO2 accumulates
Hydrogen sulfide is primary source of energy spewed out of deep sea
vents and smokers bacteria use chemosynthesis
to produce food here chemosynthetic bacteria are
food for larger organisms larger organisms thrive
because of food & heat