2. A. The Unique Nature of Pure Water
All matter is made of atoms
Elements are make from one kind of atom
A molecule is two or more different atoms combined
Water is a polar molecule; one end is positively
charged and
the other is negatively charged
3.
4. 1. The Three States of Water
Only substance on Earth to naturally exist in three states
Weak hydrogen bonds form between to the positive end
and
the negative end of different water molecules
Solid water molecules pack close together & locked in
fixed three dimensional pattern
Becomes more dense until about 4°C (get less dense) &
expands
When water freezes in fresh and marine water the ice
forms on top allowing organisms
to live underneath the ice
When marine water freezes it acts like an insulator to stop
freezing all the water
5. 2. Heat and Water
Bonds must be broken before molecules can begin to
move around
Melts at higher temperature & absorbs a lot of heat
when it melts (high latent heart of melting) and great
deal of heat must be removed to freeze it
Melting ice, added heat breaks more hydrogen bonds
than increasing molecular motion
Mixture of ice & water is 0°-adding heat goes into
melting the ice not raising temperature
High heat capacity therefore marine organisms not
affect by temperature changes in atmosphere & latent
heat of evaporation
6.
7. 3. Water as a Solvent
Dissolve more things than any other natural
substance
(universal solvent) especially salts
Salts made of opposite charged particles and conducts
electricity
Single atoms or groups of atoms
In water, strong ion charges attract water molecule,
water molecules surround the ions and pull them
apart (dissociation)
8.
9. B. Seawater
Characteristics due to nature of pure water &
materials dissolved in it
Dissolved solids due to chemical weathering of rocks
on land & hydrothermal vents
10. 1. Salt Composition
Sodium chloride account for 85% of all solids dissolved
Salinity is total salt dissolved in seawater
number of grams left behind when 1000 grams evaporated
if 35 grams left then 35 parts per thousand or 350/00 or 35
psu (practical salinity units)
Rule of constant proportions states that the relative
amounts of various ions in seawater are always the same
Differences in salinity results from removal (evaporation)
and addition (precipitation) of water
Rarely have to deal with changes in ratio of ions as result
easier to control salt & water balance
Average salinity is 35 psu and between 33-37 psu in open
ocean
Red Sea is 40 psu 7 & Baltic Sea is 7 psu
Why is Red Sea salinity so high and the Baltic Sea so low?
11. 2. Salinity, Temperature, and Density
Get denser as it gets saltier, colder, or both
-2° to 30°C
temps. below zero possible because saltwater freezes
at colder temps.
Density controlled more by temperature than salinity
There are exceptions therefore salinity & temp need to
be measured to determine density
12. 3. Dissolved Gases
O2, CO2 and N2 in atmosphere & sea surface
Gas exchange happens between the surface &
atmosphere
Dissolved gas concentration higher in cold water,
lower in warm water
Amount of oxygen in water is affected by
photosynthesis & respiration
Most oxygen is released into the atmosphere
More susceptible to oxygen depletion than
atmosphere
80% of gasses is carbon dioxide
13. 4. Transparency
Sunlight can penetrate, but it’s affected by the
material suspended in the water
Important to the photosynthetic organisms
Runoff makes coastal waters less transparent than
deep blue waters of open ocean
14. 5. Pressure
On land, organisms are under 1 atm at sea level
Marine organism have the pressure of the atmosphere &
water
With every 10m increase depth another atm is added
As atms increase gases are compressed
Organism have air bladders, floats and lungs that shrink
and collapse
Limits depth range, some organism are injured when
brought to the surface
Submarines & housing must be specially engineered to
withstand pressure
15.
16. Ocean Circulation
Throughout depths currents move and mix ocean
waters and transport heat nutrients, pollutants and
organisms
18. 1. The Coriolis Effect
Because Earth is rotating anything that moves over
the surface tends to turn a little rather in a straight line
Deflects large-scale motions like winds and currents
to the right in Northern Hemisphere and to the left in
Southern Hemisphere
19. 2. Wind Patterns
Winds driven by heat energy from sun
Trade winds
warmer at equator
wind at equator becomes less dense and air from
adjacent areas gets sucked in to replace it creating
winds
wind bent by Coriolis Effect
approach equator at 45° angle where there is no land
steadiest winds
Westerlies at middle latitudes move in opposite
direction
Polar easterlies at high latitudes
most variable winds
20.
21. 3. Surface Currents
Winds push the sea surface creating currents
Surface current moves off 45°
Top layer pushes on layer below & again Coriolis Effect
come into play
Second layer moves slightly to right and slower and is
repeated down the water column (Ekman spiral)
lower waters move progressively at greater angles from
wind
effect of wind decrease with depth
100 m no wind is felt
produces Ekman transport
upper part of water column moves perpendicular to wind
direction to right N. Hemisphere & left in S. Hemisphere
22.
23. trade winds move toward equator the equatorial
current move parallel
currents combine into huge gyres
west side of gyres carry warm water to higher
latitudes while cold current flow on eastern sides
giant thermostat warming the poles & cooling
tropics
tropical organisms like corals tend to extend into
high latitudes on the west sides of the oceans
cold loving organisms like kelp grow closest to
equator on eastern shores
24. large-scale fluctuations can cause conditions like El
Nino
current shift with season and weather
near the continental shelf currents are effect by the
shape of the bottom & coastline
25.
26. B. Thermohaline Circulation and the
Great Ocean Conveyor
Ocean water stratified
Cold more dense on the bottom & warmer less dense on
top
1. The Three-layered Ocean
Surface layer or mixed layer 100 to 200m thick
Mixed by wind, waves and currents
Sometimes in summer & spring in temperate & polar
waters sharp transition to cooler water (theromoclines)
noticed by divers
Intermediate layer depth of 1000 to 1500m
Main thermocline rarely breaks down & in open ocean
Deep or bottom layers
Below 1500 m
typically less than 4°C
27. 2. Stability and Overturn
Water column with less dense water on top and dense
water on bottom with no mixing is stable
Depends on the difference in densities between layers
If difference is small not much energy is needed to
mix the water
Downwelling occurs when top layers become more
dense & sinks
The sinking water displaces and mixes with deeper
water (overturn)
Density & temperature profiles are straight-lined
Temperate and polar during winter
28. Mixing layers extends greater into water column
Important to productivity
In intense downwelling, large volume of water may
leave without mixing
Changes in salinity at surface
Precipitation, evaporation, freezing, and temp.
Once water sunk it does not change in salinity and
temp. (water mass)
Oceanographers can follow the circulation over large
distances
Because it is driven by density (determined by temp
and salinity) the circulation is called thermohaline
circulation
29.
30. 3. The Great Ocean Conveyer
Only places where surface overturn reaches the
bottom is Atlantic south of Greenland & north of
Antartica
The sinking water spreads though the Atlantic &
other ocean basins then eventually rise to surface
and flows back
Recycles about every 4000 years
Regulates climate and alterations have produced
rapid climate changes (ie ice ages)
Bring dissolved oxygen to deep sea
31.
32. 3.3 Waves and Tides
A. Waves
Caused by wind
Wave crest moves up & forward
Trough moves down and back
Water particles do not go anywhere
Moves in a circle
Faster the longer the wind the bigger the waves
Fetch-span of open water
Larger the fetch the bigger the wave
Seas
Sharp peaks stretch over trough
Move away get faster than speed of wind
33. Swells
Once waves settle
Surf
Bottom forces water to move elongated ellipses
Wavelength get shorter
Waves “pile up” becoming higher & steeper until they
fall forward
Water affected by mixture of waves
Two crest adding to make a higher wave (wave
reinforcement)
As high as ten stories
Trough & crest combine & cancel out the wave