Salinity (#2)

What is the process of brine rejection and the formation of sea ice?

Formation of Antarctic Bottom Water in Polar Winter

What is the term for the temperature being cold at the poles and warm at the equator?

Latitudinal Inequality in Distribution of Heat

Where does the salt go? What are these locations called?

*Sinks -Sinks make the dissolved cations/anions into solids -Primary output (sink) for most elements is sedimentation *Biological materials like shells *Authigenic sediments (self made) like manganese nodules -Interaction between seawater and ocean crust (hydrothermal systems) -Isolation of shallow seas *Salts found underlying sediments at bottom of dried up seas like Mediterranean sea 6 million ya. -***Adsorption- Sticking on to clays

What is vertical circulation? How is it driven?

*Thermohaline Circulation -Changes in Temperature of Salinity -Density Driven

Why the Law of Constant Proportions?

- Even distribution from sources -*Think of the mixing bowl -Evenly distributed ions throughout ocean -*RATIO of ions to one another will be constant -Some areas could be saltier than others

What 4 components comprise the oceans?

- H2O: 96.5% - Salt: 3.5% -Life -Dust

How is the water molecule composed?

- Hydrogen attached to oxygen by covalent bonds (sharing electrons) -A dipole is formed. Polar molecule

What are anions? What is their charge?

- Ions with a NEGATIVE CHARGE

What does it mean that water is a tremendous solvent?

- It easily dissociates - + attracted to oxygen - (-) attracted to hydrogen -Saltiness/salts=Dissolved in water

What is the most likely origin of much of earth's water?

- It is an on-going process -Out-gasing of volatiles during early earth history, plus continued volcanic contributions.

Why do ice cubes float?

- Warmer things are less dense -Water reaches max density of approx 4ºC -The density of ice is lower than density of water

What does it mean that water has a high heat capacity?

-Amount of heat required to raise 1 gm of substance by 1 degree C= heat capacity - High heat capacity= Lots of head needed to change temp -Calorie= amount of heat needed to raise by 1ºC -Result= moderating effects of oceans on weather

What 3 things are related to ocean circulation?

-Change in climate -Biological Production/Fisheries -El Nino

Why is there not a 1 to 1 correspondence of what we have to put into seawater and what seawater is?

-Degree of solubility and reactivity -Consider composition of average beach sand

What are cations? What is their charge?

-Ions with a POSITIVE charge

Why aren't the oceans getting saltier and saltier over time?

-Law of constant rations - The ions are always composed in the same proportion in seawater, even if there are technically more of them

In what areas is it rainy and what areas is it dry? How is this related to salinity? (Salinity diagram)

-Low salinity= Rainy -High salinity= Dry -Salinity relatively low at 60ºN and 60ºS. Salinity low at equator (rainy) -Salinity high at 30ºN and 30ºS (dry). Very salty -Forms a sort of M shape - Polar areas are dry

Why is water special?

-ONLY substance present in all 3 phases on surface of earth -Solid, Liquid, Vapor

Where is salinity most variable? Why?

-On the surface -Because a function of evaporation vs. precipitation (climate controlled)

What is a dipole? What is an example?

-Polar Molecule -Ex=Water molecule -Water is a polar molecule

What is the principle of constant proportions? How does this relate to salinity?

-Principle of constant proportions: The absolute amount of salt in sea water varies, but the relative proportions of ions is constant -So, it is necessary to test for only one salt ion, usually chlorine, to determine total amount of salt present

Where does the salt come from? (Sources)

-Rivers and Streams (weathering products)=Most of the cations -Volcanic activity=Most of the anions -Mid-Ocean ridges and hydrothermal vents

What is salinity controlled with in relation to sea ice? Density?

-Seasonal processes of sea ice formation in winter -Sea ice melting in the spring - Salinity drives the vertical circulation of water -Dense seawater sinks

Sinks

-Take calcium carbonate from shells and make a solid -SINK: Taking things that were dissolved in seawater and making them into a solid -Sometimes ions just stick onto clays -Ions stick onto clays so they are no longer dissolving into seawater.

What is salinity? What is the average seawater salinity?

-Total amount of solid material (g) contained in 1 kg of seawater -Salinity= g of salt/kg seawater -Average seawater salinity= 34.7% - If you took 1kg of seawater and got rid of all the water, there would be 34.7g of salt -34.7 g of salt/1kg of seawater

Earth's crust vs. Seawater Why are they so different from one another?

-Water is a great solvent, but not everything dissolves equally -Silica (sand) doesn't dissolve easily -Not a 1 to 1 correspondence of what we have to put into seawater and what seawater is -CRUST: 28.2% Silica, 8.2% Aluminum, 4.3% Calcium -SEAWATER: 30.6% Sodium, almost no silica or aluminum

What is surface circulation? What is it driven by?

-Wind Driven -Atmospheric and Oceanic Circulation -Circulation of water just on the surface

Where did the oceans come from? (3 steps)

1) An earth was accumulated of smaller objects and formed a planet. Volatiles (light things) were expelled from the rocks to form the oceans and atmosphere. -Differentiated planet 2) After earth accumulated, it was bombarded by meteorites, rich in water. Some water came from meteorites 3) Some water came from icy comets

What were earth's oceans not actually solely formed by?

1) Meteorite bombardment. Not enough xenon in earth's atmosphere for this to be the case 2) Comet bombardment. Hydrogen isotopic compositions of comets are not same as seawater

What is the variability of seawater?

1) Relatively restricted range of salinities *2) Surface salinities are the most variable 3) Below 1000 meters, variability is almost not existent

What are the 2 primary things that drive ocean circulation?

1) Temperature 2) Salinity

What are the 3 unique characteristics of a polar molecule like H2O?

1) Tremendous Solvent 2) High heat capacity 3) Only substance present in all 3 phases on the surface of earth

What percent of earth's surface is water?

70%

What are the average temperatures of sea water?

Between 0ºC and 30ºC

What are the most common cations and anions in seawater?

CATIONS: *Sodium (Na), Magnesium (Mg), Calcium, Potassium (K) ANIONS: *Chloride, Sulphate, Bicarbonate

What does Latitudinal inequality in distribution of heat mean?

Cold at poles and warm at equator