Opening Assignment

• Study for your vocabulary quiz today

Assignment – when done with quiz

1. Define mass, volume, and density and explain how to measure these physical properties. (if you don’t remember these, we will go over them soon)

2. What makes the ocean salty? Please read pages 38-39 in the oceans book to find out.

• Mass: the amount of matter in an object

• Volume: the amount of space an object takes up

• Density: the amount of mass per volume D=m/v

Notes

Unit 3: Part 2 Ocean Chemistry

SalinityDensity

TemperatureDissolved Gasses

Learning Goals for Unit 3 – Part 2 Ocean Chemistry

• Students will be able to . . . – Define salinity, transparency, pressure, dissolved

gasses. – Explain how a change in salinity or temperature

will affect the density of seawater.– Describe how changes to the properties of

seawater can effect marine ecosystems.

Salinity

What is Salinity?

• Total amount of dissolved salts in the water– Measured in parts per thousand (ppt or %º)

– The average ocean salinity is 35ppt and the average river water salinity is 0.5ppt or less.

– This means that in every kilogram (1000 grams) of seawater, 35 grams are salt.

Notes

• Because the water in estuaries is a mix of fresh water and ocean water, the salinity in most estuaries is less than the open ocean.

• Bottom water almost always contains more salt than surface waters. WHY?

Notes

Where does the salt come from?

• Sources of salt in the Ocean– Weathering of the earth’s crust– Hydrothermal vents– Rain after volcanoes

Notes

What salts are in the oceans?Salt % of total salinity

Chloride (Cl-) 55

Sodium (Na+) 30.5

Sulfate (SO42-) 7.5

Magnesium (Mg2+) 3.5

Calcium (Ca2+) 1.1

Potassium (K+) 0.5

What changes the salinity of the oceans?

Salinity is changed by 3 natural processes

• Precipitation (decreases salinity)

• Evaporation (increases salinity)

• Freezing (increases salinity)

Notes

What is the relationship between salinity and density?

As salinity increases, density increases

WHY?

Notes

Global distribution of salinity

• Salinity is low at the equator and at the poles

• Salinity is high at the subtropics

• WHY?????

• Think about the 3 natural processes that change salinity…

Because…

• Salinity is low at the equator and at the poles– Precipitation > Evaporation– Precipitation > Freezing (poles)

• Salinity is high at the subtropics– Evaporation > Precipitation

Notes

Review of Yesterdays content

• Density = _________/ ______________

• As Salinity increases, density _________________

• The three processes that affect ocean salinity are _________________, ______________, and ________________

Chapter 3 - Physical Properties of Ocean Water Focused Notes

Topics:

The Unique Nature of Water pg. 40-43

Temperature, Salinity, and Density pg. 45-46

Dissolved Gases – pg. 46-48

Transparency and Pressure – pg. 48-49

Stability and Overturn pg. 49-51

•Write the questions and answer OR answer them using complete sentences where you can tell what the question was.

Opening assignment Day 3

• What does a molecule of water look like?

• Draw one in your notebook Figure 3.1 on page 41

Part 2: Temperature, Dissolved Gases, Transparency, Pressure

• Learning Goals:– Students will be able to

• Explain the unique properties of water. • Explain how temperature and density are related

and how they affect movement in the ocean• Explain the relationship between transparency and

photosynthesis• Describe the types of dissolved gases in the ocean

and the process of gas exchange

The Unique Nature of Water

• Water molecules are made of 2 Hydrogen atoms and 1 oxygen atom chemically bonded.

• They are unusual because they attract each other. They do this because the hydrogen atoms have a slightly positive charge and the oxygen atom has a slightly negative charge.

• Hydrogen bonds are the type of bonds that attract water molecules to each other.

• They are weak bonds so they are constantly breaking apart and reforming.

The Unique Nature of Water

Review of Temperature in States of Matter

• Water is found on Earth in all 3 states of matter; solid (ice), liquid, gas (water vapor)

• To change from one state to another you just need to add or remove heat.

• Water is the only substance that becomes LESS dense as it becomes a solid.

• When water molecules freeze they expand and become less dense causing them to float.

The Unique Nature of Water

Heat Capacity

• Heat capacity is the amount of heat needed to raise a substances temperature by a given amount.

• Water has one of the highest heat capacities of any naturally occurring substance.

Water is the Universal Solvent

• Water can dissolve more things than any other natural substance on Earth and is therefore called the Universal Solvent.

Temperature, Salinity, and Density

• Remember that we have already learned that as salinity increases, density _______________.

• The density of ocean water is primarily influenced by temperature though.

• What do you think happens to density when temperature increases?

What is the relationship between temperature and

density?

• As temperature increases, density decreases . . . WHY?

As energy is added to molecules they move faster and farther apart . . . decreasing the amount of mass per volume.

Ocean water and freezing

• Ocean water is less prone to freezing than rivers and lakes due to it’s salinity level. Salt water freezes at a lower temperature (colder) than freshwater.

Dissolved Gasses

• Three most important gasses are:– Oxygen (O2)

– Carbon Dioxide (CO2)

– Nitrogen (N2)

• These gasses are found in air and dissolve into seawater at the surface– Also, gasses dissolved into seawater may be

released to the atmosphere

Effect of temperature

• Gasses dissolve better into colder water

• Dissolved gasses are higher in polar waters than at the tropics

Oxygen• Oxygen does not

dissolve into seawater very well– Air has 210 mL/L/

seawater has 0-8 mL/L

– Dissolved oxygen is referred to as DO by marine scientists (and that’s what we’ll call it too)

Why would DO increase at the bottom of the ocean?

• Lower temp water can hold more DO

• Deep water originated at the surface (remember thermohaline circulation)

DO

• Amount of DO is affected by the processes of photosynthesis and respiration– Producers (organisms that make their own

food) use photosynthesis which PRODUCES oxygen

– Consumers (organisms that consume food) use respiration which CONSUMES oxygen

What do plants have to do with DO?

• A region with a lot of plants or phytoplankton will have greater DO than areas without.

Most of the oxygen that is produced by these photosynthetic organisms is released into our atmosphere. They supply our atmosphere with over 50% of the oxygen!!

Carbon Dioxide

• CO2 dissolves better in seawater than oxygen– CO2 makes up 80% of all dissolved gasses in

the ocean (but only .04% of air!!!)

– This is important because CO2 is a greenhouse gas (gas that contributes to global warming

– What would happen if the ocean got warmer?

Vertical profile of DO

• REMEMBER, producers need sunlight for photosynthesis so we usually see higher DO in the __________ zone.

• Just below the _______ zone there is a region of very low DO called the oxygen minimum zone.

• Deeper than the oxygen minimum zone the DO increases again.

What is transparency?The ability of an object (in this case seawater) to allow light to pass through it.

Transparency is important in the ocean because photosynthetic organisms need light!

Transparency

• Sunlight contains all colors of the rainbow, HOWEVER not all colors penetrate seawater equally

• Water acts as a filter to the light– Red light is filtered out first

• Red objects appear black or grey at depth

– Blue light reaches the deepest– Filtering order is:

• Red Orange Yellow Green Blue

Graph of Transparency

What affects the transparency of seawater?

• Dissolved and suspended material– (a.k.a. “stuff” in the water)– Muddy water is less transparent that clean

water– Coastal waters are less transparent then open

ocean waters (WHY?)

Pressure• The weight

exerted over a unit area of surface– Measured in

atmospheres (atm)

– 1 atm= 14.7 p.s.i. (pounds per square inch)

Pressure and depth

• As you go deeper in the ocean there is more water over you, so there is more pressure

• With every 10 meters (33 ft) of depth the pressure increases by one atm– So, at 10 meters, there is twice the pressure

on your body than there is right now!

How does this affect organisms that live in the ocean?

• Pressure is only a problem for animals with air filled spaces because the increased pressure causes them to compress– Lungs of mammals– Swim bladders of

bony fish

How many atmospheres of pressure are on your body at 80

meters?

9 atm (b/c the atm of air pressure still counts!)

Review Summary – Copy and complete the following

1. Why is transparency important in the ocean?2. Which color of light is filtered out by seawater

first?3. Which water has better transparency: coastal

or open ocean? Explain why.4. Complete the following relationships:

– As salinity increases, density __________– As temperature decreases, density _______– As depth decreases, pressure _________

Video clips on Ocean

• Why is the ocean blue?• http://www.youtube.com/watch?v=9hzUJAIii3E

• Why are oceans salty?• http://www.youtube.com/watch?v=aFXn1d5baCo

Opening Assignment

Make 3 quantitative observations about this density column.

Density and Salinity LabLearning Goals

• Students will be able – Explain the relationship between density and

salinity

– Describe how density and salinity affects the movement of objects in ocean water

– Infer how an increase in global atmospheric temperature would affect sea surface salinity levels and therefore effect marine organism

Salinity and Density Lab Beaker Contents

• Beaker #1: Clear tap water

• Beaker #2: Clear very salty water

• Beaker #3: Blue tap water

• Beaker #4: Red slightly salty water

• Beaker #5: Green very salty water

Opening Assignment

• Why is there more dissolved Carbon Dioxide in the ocean than Oxygen?

• Why is ocean water less prone to freezing than freshwater lakes or rivers?

Label your notebook paper

• Thermohaline Circulation – Temperature and density lab

• https://www.youtube.com/watch?v=w_8mw-1HYFg

Thermohaline Circulation

• Thermohaline circulation is a global ocean current system that is driven by differences in temperature (thermo) and salinity (haline); both factors that influence the density of seawater.

• Thermohaline circulation has an important role in regulating the climate of the earth and the properties of deep sea water.

Notes

Thermohaline Circulation (TC)

• Thermohaline circulation (TC) is very important because it carries oxygenated water to the deep ocean– Strong TC= well oxygenated ocean– Weak TC= ocean stratification and deep water anoxia

(lacking oxygen)• During winter:

– storms mix (and oxygenate) water AND– Cold water can hold more oxygen

• Pattern of circulation depends on the position of the continents and oceans (which changes over time due to plate tectonics)

Thermohaline Circulation

Temperature and Density Lab• Follow the directions for Part A and then

document your observations under the notes we just took.

• Do the same thing for Part B.

• Copy the graph in Part C and use the data in the chart to plot 2 different lines; one for surface temperature and one for surface density.

Analyze and Conclude

• Answer the analyze and conclude questions under the graph you have created. You do not need to write the questions.

Opening Assignment Day 5Copy and answer the following

• For every ______ meters of depth the pressure increases by 1 atm.

• If I were to dive to a depth of 40 meters, how many atmospheres of pressure would I experience?

• Thermohaline Circulation depends on what two physical properties to effect density?

Review of Labs

• Please pull your lab sheets out so we can go over your answers.

• For those that did not finish this is an opportunity to complete it and turn it in for full credit.

Label your notepage“Human Impact on Ocean Water”

• What do you think are ways that humans impact our oceans?

• 3 Primary negative effects of human activity on our oceans– Pollution– Overfishing– Ocean acidification

Pollution

• While watching this video clip, take notes on how humans pollute our oceans.

• http://www.abc.net.au/catalyst/stories/3583576.htm

• Can you think of any other ways we are polluting our oceans?