“Composition of Seawater”
 “Composition” = 
	  What it’s ________ of.
•	3.5% dissolved minerals
–	Salts!
“Salinity.”
“Salinus” = salt
•	Salinity = amount of salt dissolved in water
•	Parts per 1000 = ‰
•	Most of the salt in seawater = common table salt.
•	Sources of Salts
1 -- Weathering!
–	Chemical weathering of rocks on continents
–	Erosion by rivers
–	Deposition in ocean

2	-- Earth’s interior!
–	Volcanic eruptions
What affects Salinity?
1	-- Amount of salt is constant
2	-- Amount of water changes
    3 -- Ocean Tempo Variation.
•	Tempo changes with Solar Radiation.
–	Latitude.
•	Tempo changes with depth.
–	Thermocline = “heat” + “slope”
–	Layer of ocean water with fast change in tempo.
Density Variation
Density = Mass ÷ Volume
–	How heavy for size…

↑ Dense = Sinks ↓
•	↑ Salinity = ↑ Density
•	↑ Tempo = ↓ Density

Ocean Layers
Layered by density.
•	Surface Zone
–	Shallow
–	Mixed (waves & wind)
•	Transition Zone
–	Thermocline
–	Pycnocline
•	Deep Zone
–	No sunlight
–	Cold & Dense
REVIEW:
•	If we poured a cup of salt into our aquarium what would happen to the salinity of the water?
•	What is the difference between a Thermocline and a Pycnocline?
•	Where is the densest layer of the ocean located? What is it called?