Properties of Ocean Water

What is ocean water made of?  Water!  Other substances: Salts – including NaCl – KCl – CaCl 2 MgCl 2 con’t next page

 Other substances in Ocean water Organic matter- living and dead animals and plants Dissolved gases CO 2 O2O2O2O2 N2N2N2N2

Why are dissolved gasses important and how did they get there?  CO 2 – what produces it, uses it?  O 2 – what produces it, uses it?  N 2 – what produces it, uses it?  Fish tank vs. natural ocean

Gases and solids dissolve in ocean water…..  What affects the solubility?  Temperature?  Solids are more soluble in _____ water. Ex: sugar in water Ex: sugar in water  Gases are more soluble in _____ water. Ex: what happens to a warm bottle of soda? Ex: what happens to a warm bottle of soda?

What does this mean for oceans?  Gases dissolve better in colder areas  In surface layer of oceans, there can be… More oxygen, carbon dioxide in polar areas More oxygen, carbon dioxide in polar areas Less oxygen, carbon dioxide in tropical areas Less oxygen, carbon dioxide in tropical areas

What is salinity?  The total amount of dissolved salts in seawater.

Salinity 1 % is 1 in 100 (familiar with this) 1 % is 1 in 100 (familiar with this) But salinity is usually expressed But salinity is usually expressed in parts per thousand 0/00in parts per thousand 0/00 1 o/oo is 1 in o/oo is 1 in 1000 Ex: 3.3 % is 3.3 percent = same as Ex: 3.3 % is 3.3 percent = same as 33 o/oo, 33 parts per thousand33 o/oo, 33 parts per thousand Ocean water is avg 3.5% OR _______ o/oo. Ocean water is avg 3.5% OR _______ o/oo.

How can salinity in the ocean change?  Let’s think about a beaker of fresh water…………………let’s add salt  The salinity is a certain o/oo  How can we change the salinity in the beaker?

Two ways to change salinity…  Change the amount of dissolved substances add/remove salt add/remove salt  Change the amount of water molecules add/remove water add/remove water

How can we decrease the salinity?  Add fresh water!!  What natural processes add water to the oceans? Precipitation Precipitation River and stream run-off River and stream run-off Snow/glacier melting Snow/glacier melting

Can also remove/lose salt..   Waves breaking on land   salt particles go into the atmosphere.

How can we increase the salinity in the beaker?  Remove water? How?  What natural processes remove water from the oceans? Evaporation Evaporation Leaves salts behindLeaves salts behind At the beach, ocean water evaporates off your arm and leaves salt on your skinAt the beach, ocean water evaporates off your arm and leaves salt on your skin Freezing – same idea, ice is fresh water Freezing – same idea, ice is fresh water

Adding salt to Sea Water  1. erosion from continental rock  2. volcanic eruptions (land and in the ocean)  3. from the atmosphere  Which has the quickest, biggest effect on salinity? Add/remove fresh water? Add/remove fresh water? Add/remove salt? Add/remove salt?

It’s the fresh water!  That can happen quickly Precipitation, etc Precipitation, etc Also large volumes of water can be added and removed quickly! On the other hand, it takes a long time for more salt to enter the oceans or to be removed naturally!

Salinity of ocean has not changed for millions of years  How can this be?  Within large areas of ocean, a lot of mixing  Even though there are changes with the seasons, The average salinity is steady The average salinity is steady Additions/deposits are used by marine plants, animals Additions/deposits are used by marine plants, animals

Salinity varies- open ocean (far from land) o/oo How salty is the ocean?

 Salinity EXTREMES Baltic Sea 10 o/oo Baltic Sea 10 o/oo Why? Water here is brackish- fresh water mixes with sea water

More salinity extremes  The Red Sea 42 o/oo Why?

 The Red Sea is located in a tropical area high evaporation high evaporation limited open ocean circulation. limited open ocean circulation.  got its name because of a type of algae called Trichodesmium erythraeum which is found in the sea. When these blooms of algae die off, they appear to turn the blue- green color of the ocean to a reddish- brown.

More…. extremes!!!  Inland Bodies of Water Great Salt Lake 280 o/oo Great Salt Lake 280 o/oo Dead Sea 333 o/oo Dead Sea 333 o/oo

How about the salinity of the water we drink?  Tap water.8 o/oo  Good Tasting water.6 o/oo  Bottled water.3 o/oo  Distilled water zero!

What areas of the world have the greatest variation in salinity?

______________ Areas  hot and rainy!

Tropical Areas  ___ salinity – hotter so more evaporation  ___ salinity – rainy season – increased precipitation

_________Areas

Polar Areas  ____ salinity –in winter –increased freezing  ___ salinity – in summer- increased melting of snow

_________Areas

Coastal Areas  ___ salinity – receives river/stream run-off

What does it matter that salinity changes or that the ocean is salty at all?  Does the salinity affect the properties of ocean water?  Let’s review water’s properties Surface tension Surface tension Phase change – freezing/boiling point Phase change – freezing/boiling point Heat capacity Heat capacity Solubility Solubility density density

Density  Demo: Egg sinks in fresh water Egg sinks in fresh water Egg floats in salty water Egg floats in salty water What does this mean? What does this mean? Sink vs float is related to density of object compared to the liquid it’s inSink vs float is related to density of object compared to the liquid it’s in Salty water is MORE DENSE than fresh water Salty water is MORE DENSE than fresh water

Phase change, freezing/boiling  Why do we sprinkle salt on icy roads?  Salt melts the dangerous ice  What does the salt do to the freezing point of water?  It reduces the freezing point  In other words, water stays liquid at lower temperatures, below 0C

Solubility  That’s why we have salts and stuff in the ocean in the first place!!  The water itself dissolves SOOO many substances  It all ends up in the oceans!

Surface tension  Re-doing the penny dropper lab? Would salt have same effect as soap? Would salt have same effect as soap? Scientists study surface tension of ocean water Scientists study surface tension of ocean water Affects marine lifeAffects marine life Affects foaminess, mixing of air into ocean waterAffects foaminess, mixing of air into ocean water

Heat capacity  Addition of salt does not affect water’s heat capacity Still high compared to other substances Still high compared to other substances Heat capacity of the huge volume of oceans affects movement of energy within the oceans transfer of energy to air – land - oceans

Summary

What effect does this all have on the movement of ocean water?  If salty water is more dense…..  If cold water is more dense……  Bill Nye will help explain it!  1HYFg 1HYFg 1HYFg