Transcript Seawater Chemistry

Seawater Chemistry &
Ocean Stratification
1
Key Points
• The salt in seawater is due in part
to water’s unique properties.
• Seawater density is influenced by
temperature and salinity.
• The ocean has layers as a result of
different densities.
How did the Ocean get so salty?
• Through a combination of water’s properties
(universal solvent, adhesion) water “picks
up” minerals via erosional and weathering
processes
• In other words, water physically and
chemically picks up salts
• Make way to the ocean
Hydrological Cycle (Water Cycle)
4
What types of elements are
found in the ocean’s salts?
6
How do we measure the
amount of salt in the Ocean?
• Salinity vs.
Conductivity
• CTD Rosette
– Conductivity
– Temperature
– Density
7
Key Points
• The salt in seawater is due in part to
water’s unique properties.
• Seawater density is influenced by
temperature and salinity.
• The ocean has layers as a result of
different densities.
How is the
Ocean Like a
Red Velvet
Cake?
Ocean Model
Temperature
Warmer
Depth
Surface
Colder
Deeper
10
Ocean Model
11
Ocean Model
“Warm” shallow surface layer
Transition Zone
Cold deep layer
How do the layers form?
12
Surface
Layer
Transition
Zone
Homogeneous Ocean
Deep
Water
13
Ocean Temperature
Surface Layer
Thermocline = Temperature Change
Transition Zone
Deep Water
• 90% of the total volume
of ocean is this cold, deep
water.
•At depths greater than
1000m, temperature is
approximately 4ºC (even
in the tropics!!).
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Why do layers form?
14
Because of Density
http://www.youtube.com/watch?v=w_8mw-1HYFg
Mass per unit volume
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Denser
3
3
1.022
19,300
to 1.030
kg/m
g/cm
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Lighter
Lighter
kg/m
3
100
1.000
g/cm
3
Ocean Density
Surface Layer
Pycnocline
Pycnocline = Density Change
Transition Zone
Deep Water
• Seawater density is
controlled by Temperature
and Salinity
•In the ocean, Temperature
has a greater effect on
density
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16
Surface
Layer
Transition
Zone
Thermocline
& Pycnocline
Boundary
Deep
Water
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Warmed and lit by sun
Mixed
Surface
Layer
Boundary
Photosynthesis
Less Nutrients
Cold, Dark, No Photosynthesis , More Nutrients
Deep
Water
18
Main Differences…
•
•
•
•
Surface Ocean
Warm
Lit by the sun
Has photosynthesis
Less nutrients
Deep Ocean
•
•
•
•
•
Cold
Dark
No photosynthesis
More Nutrients
LOTS AND LOTS OF
PRESSURE
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