Properties of Ocean Water Oceans Properties of Ocean Water

Why are Oceans Important? Generates 70% of our oxygen Absorbs CO2 from atmosphere Drives climate and weather Stabilizes temperature Shapes Earth’s chemistry Economy – fish, salt, pleasure https://www.ck12.org/c/earth-science/importance-of-the-oceans/lecture/Exploring- Oceans/?referrer=concept_details

Global Ocean 71% of Earth’s surface is covered by liquid water - most of it is in oceans. There are five main oceans on Earth. As they are all connected, scientists often refer to them as the global ocean. How many can you name?

5 Main Oceans: divided by continents Pacific Ocean Atlantic Ocean Indian Ocean Southern Ocean from coast of Antarctica to 60Deg Lat Arctic Ocean – mostly covered by ice

How did oceans form? Ash, dust, and gases, water vapor from volcanoes formed the atmosphere. Earth slowly cooled. When cool enough, water vapor in the atmosphere condensed. The liquid water fell as rain, filled the basins in Earth’s surface, forming the oceans.

What’s in Ocean Water? 96.5 percent water, 2.5 percent salts, smaller amounts of other dissolved substances, particulates, a few atmospheric gases.

Much of the world’s magnesium is recovered from seawater. And large quantities of bromine. In certain parts of the world, sodium chloride (table salt) is still obtained by evaporating seawater.  It is toxic. Bromine is used in many areas such as agricultural chemicals, dyestuffs, insecticides, pharmaceuticals and chemical intermediates. Some usesare being phased out for environmental reasons, but newuses continue to be found. Bromine compounds can beused as flame retardants.

How do these particles get into the ocean? Rivers dissolve minerals and carry them to the ocean. Wind blows particles in (possibly thousands of km from their source. Hydrothermal vents from below earth’s crust Organisms in ocean convert dissolved materials to solids, which eventually settle to greater oceanic depths.   Chemical reactions with in the ocean

What Makes Ocean Water Salty? Dissolved salts are mostly sodium chloride, but also some other dissolved solids (Mg and Ca). https://www.youtube.com/watch?v=EIDSMzXXzLM

What is Salinity? Salinity is a measure of the amount of dissolved salts in a certain amount of liquid. Average salinity is approximately 3.5%, or 35 parts per thousand. This means that for every 1 litre (1000 mL) of seawater there are 35 grams of salts (mostly, but not entirely, sodium chloride) dissolved in it. 35 g dissolved solids/kg of dissolved solids If you evaporated 1 kg of ocean water, 35 g of solids would remain.

How do we Measure Salinity? Scientists measure electrical conductivity of water. Salt dissolved in sea water makes it possible for an electrical current to pass through. The greater the quantity of dissolved salts, the more easily current flows. Conductivity increases as salinity increases

Processes that Affect Salinity

Processes that Decrease Salinity: Precipitation Sea Ice melting

Processes that Increase Salinity: Evaporation Formation of Sea Ice

Effects of Location on Salinity Oceans in hot, dry climates have high salinities. (the hot weather causes water to evaporate quickly). Salt is left behind. For example, the Red Sea in the Middle East is very salty. The climate there is very hot and dry. Some parts of the ocean are less salty than others: Near coastlines, fresh water from streams and rivers runs into the ocean. As fresh water mixes with ocean water, the salinity of the ocean water decreases.

Density Knowing salinity and temperature helps us determine ocean density. Density is a mass per unit volume. Density of sea water is influenced by salinity and temperature

Why is knowing Density Important? Knowing density helps us understand how water masses move through the ocean and mix together (ocean currents) Ocean currents have major impact on climate.

What affects Ocean Temperature? Ocean’s temperature varies with amount of solar radiation received (heat from the sun) Depends on Latitude.

Latitude affects Ocean Temperature The further away from the equator, the less sunlight is received. At the poles the Sun never rises very high in the sky and sunlight filters through a thick wedge of atmosphere. https://www.ck12.org/earth-science/latitude/lesson/Effect-of- Latitude-on-Climate-HS-ES/

Latitude Affects Temperature Surface water at the equator can be up to 30°C. In the polar oceans, water at the surface can be as cold as 1.9°C.

Time of year can affect Ocean temperature In areas that receive more sunlight in summer than winter, the surface water in the oceans is warmer.

Ocean Depth Affects Ocean Temperature p314

Ocean Temperatures vary with Depth

3 Ocean Layers Shallow surface zone Transition Zone (Thermocline) Deep Zone

Surface Zone – top layer Shallow (300-450 m) Warmed by sun As the ocean water is heated, it becomes less dense and rises above denser, cooler water. Convection currents form as the water moves. temperature within the surface zone is fairly uniform. Plankton live here.

Transition Zone - Thermocline just beneath the surface zone. Rapid temperature drop Bottom is very cold, even at the equator warm water of the surface zone do not mix easily with the water below. Variable depth: 100 m to almost 1,000 m below the surface of the ocean. Nekton live here

Deep Zone No Sunlight very cold (2°C), very dense. It moves slowly across the ocean floor and forms the deep ocean currents. Bottom dwellers live here

Practice Ocean WS Or p313 #4-7: salinity P315 #8-10: describing ocean layers P321 Critical Thinking 1-3: Interpreting a density graph p112 -113 prentice Hall WB

Water is a polar molecule Ted ed https://ed.ted.com/lessons/how-polarity-makes- water-behave-strangely-christina-kleinberg

Activity: Water Olympics