Transcript SeaWater properties

Mid Atlantic Ridge – new findings:
• http://www.noc.soton.ac.uk/gg/classroom
@sea/JC007/about.html
• http://www.sciencedaily.com/releases/200
7/03/070301103112.htm
http://www.noc.soton.ac.uk/gg/classroom@s
ea/JC007/background.html
Properties of Seawater
WORLDS WATER SOURCES:
Learning Objectives
1. Understand the nature of the water molecule and its unique
properties (polarity, density and thermal properties) and how
these are altered by the presence of salt in solution.
Review of:
Atoms
Temperature
Heat
Thermodynamics
Internal Energy and Entropy
2. Know the types of materials that are dissolved in sea water,
their importance and how they vary with time.
3. Explain variations in salinity, temperature, and pressure
within the sea and how they alter the chemical and physical
properties of the ocean.
States of Matter (e.g. water)
States of Matter (e.g. water)
Atomic Structure
http://www.dayah.com/periodic/Other/Periodic%20Table.pdf
Hydrogen bonds –
cohesion - surface tension!
The formation of ice in freshwater:
Density of freshwater:
Seawater density depends on temperature,
salinity and pressure! Therefore, it increases
with > salt content at const. temp;
high density in cold, salty waters –why is this
important?
Why does ice float on water?
Water is a powerful solvent:
(“the universal solvent”)
Sodium Chloride
Rock SALT
NaCl
Na

Cation
Cl
Ions

Anion
Cycling of dissolved
components in seawater:
Did oceans’ salinity increase over time?
Major dissolved components in seawater:
35 g of salt in 1000 g of seawater
The layer of rapidly
changing salinity
with depth; 3001000 meters;
Same as
pycnocline
(density) and
thermocline;
Salinity map showing areas of high salinity (36 o/oo) in green,
medium salinity in blue (35 o/oo), and low salinity (34 o/oo) in
purple. Salinity is rather stable but areas in the North Atlantic,
South Atlantic, South Pacific, Indian Ocean, Arabian Sea, Red Sea,
and Mediterranean Sea tend to be a little high (green). Areas near
Antarctica, the Arctic Ocean, Southeast Asia, and the West Coast
of North and Central America tend to be a little low (purple).
http://www.biosbcc.net/ocean/marinesci/02ocean/swcomposition.htm
pH = potential/power of
hydrogen
Carbonate buffering system keeps
the pH of seawater constant = 8.1
Carbonate Buffering System
Waters Thermal Properties
What is temperature?
What is temperature?
using  Kinetic temperature definition
What is temperature?
It is a direct measure of the average kinetic energy of
atoms and molecules that make up substance. Temp.
changes when heat energy is added to or removed
from a substance.
It is measured in (Celsius, Kelvin, and Fahrenheit).
HEAT
(the energy of moving molecules =
kinetic energy)
1) Represents the transfer of energy from
high to low temperature. Therefore, heat
has units of Energy (1 calorie, calor = heat;
the amount of heat required to raise the
temp. of 1 gram of water by 1 C°);
2) An object does not possess "heat"; the
appropriate term for the microscopic energy
in an object is internal energy.
First Law of Thermodynamics
Heat Capacity – the amount of heat required
to raise the temp. of 1 g of any substance by
1 °C;
– Water has one of the highest heat
capacities known, which makes water
excellent heat transfer material; and
– therefore, allows ocean currents to
moderate global climate!
Atmospheric transport of surplus heat from low latitudes
into heat deficient high latitudes areas:
Learning Objectives:
Ocean Sediments
1. Understand the origin and classification of marine
sediments.
2. Explain the factors controlling origin and deposition of
sediment on the continental shelf and in the deep ocean.
Questions:
1. Why don't the oceans have more sediment in them? Where does it all
go? Earth is 4.6 billion years old and the oceans should have more
sediment in them.
2. Salt composition of the oceans has not changed for the last 1.5 billion
years. Explain why?
Learning Objectives:
Plate tectonics and Ocean floor
Understand the processes that are continuously changing Earth’s
surface as lithospheric plates move relative to one another.
Identify the role of oceanic ridges, transform faults and deep-sea
trenches in defining the edges of lithospheric plates.
Understand the importance of asthenospheric thermal convection
in plate tectonics and the resulting compression or tensional forces
at the plate boundaries.
Explain the distribution of magnetic anomaly stripes, seismicity,
and volcanism in terms of the concept of global plate tectonics.
Spreading rates of ocean basins.
Difference between oceanic and continental crust.