Earth Science Unit 8 Oceanography Suggested Time: 3 Weeks In this unit, students will investigate and understand that oceans are complex, interactive physical, chemical, and biological systems that are subject to long and short-term variations. Many topics within this unit have been covered in previous units and so only a review of the topics is necessary. Emphasis should be made on physical and chemical changes, systems interactions, and features of the sea floor. In addition, it is very important that students realize the importance of environmental and geologic implications and understand the economic and public policy issues concerning the oceans and coastal zone of the Chesapeake Bay. This unit is intended to provide ample curriculum for the time period after the Standards of Learning tests. Teachers should seek out activities that are student-centered and research-based for a final project in the course. BIG IDEAS: The ocean is a system where many changes take place which have an impact on its economic and environmental importance.
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Earth Science Unit 8
Oceanography
Suggested Time: 3 Weeks
In this unit, students will investigate and understand that oceans are complex, interactive
physical, chemical, and biological systems that are subject to long and short-term variations.
Many topics within this unit have been covered in previous units and so only a review of the
topics is necessary.
Emphasis should be made on physical and chemical changes, systems interactions, and features
of the sea floor. In addition, it is very important that students realize the importance of
environmental and geologic implications and understand the economic and public policy issues
concerning the oceans and coastal zone of the Chesapeake Bay.
This unit is intended to provide ample curriculum for the time period after the Standards of
Learning tests. Teachers should seek out activities that are student-centered and research-based
for a final project in the course.
BIG IDEAS:
The ocean is a system
where many changes take
place which have an
impact on its economic
and environmental
importance.
STAGE 1 –Desired Results
UNIT 8 BIG IDEAS:
Instructional Focus Standards of Learning Essential Knowledge and Skills Virginia Beach Objectives
Virginia Department of Education Expectations
8.1
Oceanography
ES.10 The student will
investigate and
understand that
oceans are
complex,
interactive
physical,
chemical, and
biological systems
and are subject to
long- and short-
term variations.
Key concepts
include
a) physical and
chemical changes
related to tides,
waves, currents, sea
level and ice cap
variations,
upwelling, and
identify the effects of
human activities on the
oceans.
analyze the potential impact
of a major environmental
disaster on the base of the
food web and vertebrate
organisms; economics;
cultures; and future
productivity.
analyze the relationship
between moving continents,
the presence of ice caps, and
ocean circulation over long
periods of time.
relate important ocean
conditions, including El
Niño, to weather on the
continents.
evaluate the role of the
Explain how the ocean is a dynamic system including
chemical, biological and physical systems (food and
mineral resources, recreation, transportation, and sea
level change). (8.1.1)
Describe the composition of sea water and variations in
salinity concentrations, including where fresh and salt
water mix (estuaries). (8.1.2)
Relate water temperature differences during a yearly
cycle to the formation of storms in the Atlantic Ocean
and Gulf of Mexico. (8.1.3)
Describe variations in sea level and ice caps and the
resulting effects (salinity, density and currents). (8.1.4)
Describe the physical properties of waves and how they
are generated by wind. (8.1.5)
Explain the causes and effects of tides. (8.1.6)
Explain the causes and effects of ocean currents
including the distribution of heat from the equator to the
poles. Predict what changes may occur as continents
move and atmospheric conditions and climate vary.
(8.1.7)
Analyze the relationship between moving continents,
The ocean is a system where many changes take place which have an impact on its economic and environmental
importance.
Enduring Understandings: Essential Questions:
The ocean is a dynamic system in which many chemical,
physical, geological, and biological changes take place.
The oceans are environmentally and economically important.
How do geological, physical, chemical and biological systems interact
in the ocean?
What is the interdependency between humans and oceans?
salinity variations;
b) importance of
environmental and
geologic
implications;
c) systems
interactions;
d) features of the
seafloor as
reflections of
tectonic processes;
and
e) economic and
public policy issues
concerning the
oceans and the
coastal zone
including the
Chesapeake Bay
marine environment in the
extraction of carbon dioxide
in carbonates and the
production of oxygen.
analyze the role of ocean
currents in the distribution
of heat from the equatorial
regions to the poles, and
predict what changes may
occur as continents move
and atmospheric conditions
and climate vary.
compare Atlantic Ocean and
Gulf of Mexico water
temperatures during the
yearly cycle, and relate this
to the formation of storms.
describe how different types
of pollution can pollute the
Chesapeake Bay even
though the pollutant source
may be hundreds of miles
from the Bay.
the presence of ice caps, and ocean circulation over long
periods of time. (8.1.8)
Identify that the ocean is the largest reservoir of heat
and that the stored heat drives the weather. Explain
how this causes differences in climate between areas
near the ocean and the interior of a continent. (8.1.9)
Explain how upwelling brings cold, nutrient-rich water
from the deep ocean to the surface and how these areas
have rich biological activity. (8.1.10)
Identify features of the sea floor to include continental
Salinity of Ocean Water If you were to view the planet Earth from space, you would see that most of its surface is covered by water. Most of this is ocean water which cannot be consumed. Why can’t ocean water be consumed? The reason is that ocean water contains large amounts of salt, which make it undrinkable.
Salinity is a measurement of the saltiness or concentration of salt in water. Ocean water contains many different salts, but the most abundant is sodium chloride, also known as table salt. Sodium chloride makes up 86% of all the ions present in ocean water. Other salts that can be found in ocean water at significant levels are calcium chloride and magnesium chloride.
Why is the ocean salty? When the Earth was being formed, volcanoes ejected large amounts of lava and chemicals (including salts) into the oceans and atmosphere. Some of these salts dissolved in the water. Rain also washes salts from the land into the ocean. Over time the level of dissolved salts in the oceans increased to the level it is today.
While the average salinity of ocean water is 35 ppt. there are several factors that can increase or decrease its salinity. At the polar regions, freezing of ocean water increases the salinity of the surrounding water. Evaporation in hot arid regions also increases the salinity. The Dead Sea, located in Israel, has a salinity nearly seven times that of most ocean water. At the ocean’s surface, rain, snow, and melting ice are all responsible for decreasing the salinity. As rivers enter the ocean, they carry large volumes of fresh water into the ocean, causing the salinity to decrease.
In this experiment, you will use a Conductivity Probe to measure the salinity of salt water. In Part I, you will measure the change in ocean salinity due to evaporation. In Part II, you will measure the change in salinity near the mouth of a river as it flows into an ocean.
OBJECTIVES
In this experiment, you will
Measure salinity of water sample using Conductivity Probe. Determine the effect of evaporation on the salinity of ocean water. Determine the salinity change when a river flows into an ocean. Calculate salinity changes.
MATERIALS
LabPro interface text book (5 to 10 cm thick) Palm handheld masking tape Data Pro program plastic tubing Vernier Conductivity Probe plastic syringe 2 aluminum pans wash bottle with distilled water large plastic tub lamp with a 60 W (or greater) bulb medium plastic tub 400 mL beaker ring stand 1.5 L saltwater test tube clamp 1 L distilled water
PRE-LAB QUESTIONS
1. In Part I of this experiment, you will shine a light on an aluminum pan filled with saltwater. Another pan filled with saltwater will be kept out of the light. What do you predict will happen to the salinity in each pan?
Figure 1 2. In Part II of this experiment, you will setup two tubs of water. The freshwater from the
smaller tub will slowly flow into the larger tub with saltwater. What do you predict will happen to the salinity in the larger tub?
Figure 2
PROCEDURE
1. Plug the Conductivity Probe into Channel 1 of the LabPro interface. Connect the handheld to the LabPro using the interface cable. Firmly press in the cable ends. The switch on the Conductivity Probe should be on the 0-20000 S/cm setting.
2. Press the power button on the handheld to turn it on. To start Data Pro, tap the Data Pro icon on the Applications screen. Choose New from the Data Pro menu or tap to reset the program.
3. Set up the handheld and interface for the Conductivity Probe.
a. On the Main screen, tap .
b. If the handheld displays TDS(mg/L) in CH 1, proceed directly to Step 4. If it does not, continue with this step to set up your sensor manually.
c. Tap to select Channel 1.
d. Press the Scroll buttons on the handheld to scroll through the list of sensors.
e. Choose CONDUCT 10000(mg/L) from the list of sensors.
4. Set up the data-collection mode.
a. On the Setup screen, tap and choose Single Point.
b. Tap to return to the Main screen. 5. Obtain 500 mL of the saltwater provided by your teacher.
6. Measure the initial salinity of your saltwater.
a. Rinse the probe with distilled water and gently blot it dry with a tissue.
b. Lower the probe into the saltwater so that the hole in the probe end is completely submerged as shown in Figure 3. Swirl the solution briefly.
c. Tap to begin sampling.
d. After 10 seconds, the salinity concentration will appear on the screen.
e. Record the salinity in the data table. The units are mg/L.
f. Tap to return to the Main screen.
g. Rinse the probe with distilled water and gently blot it dry with a tissue.
Part I Sunlight
Day 1
7. Obtain two aluminum pans and a desk lamp.
8. Set up the lamp and place one of the aluminum pans in front as shown in Figure 1.
9. Pour 250 mL of saltwater into the aluminum pan.
10. Turn on the lamp and position the bulb so that it is pointing down towards the pan. The lamp bulb should be positioned so that it is 10 cm from the water in the pan.
11. Place the second aluminum pan a few feet away from the light. Pour 250 mL of saltwater into the pan and let both sit overnight.
Day 2
12. Turn off the desk lamp and slide the pan out from under the light.
13. Carefully pour the saltwater from the pan into a clean beaker. Label the beaker “Light”.
14. Carefully pour the saltwater from the second pan into a second beaker. Label this beaker “No Light”.
15. Repeat Steps 1 – 6 to measure the salinity of both beakers.
Part II Freshwater Rivers
16. Repeat Steps 1 – 6. Only this time, you will need 1 liter of saltwater.
17. Set up the data-collection mode.
a. On the Main screen, tap .
Figure 3
b. While still on the Setup screen, tap .
c. Enter “5” as the time between samples in seconds, using the onscreen keyboard (tap “123”) or using the Graffiti writing area.
d. Enter “120” as the number of samples. (The length of the data collection will be 10 minutes.)
e. Tap twice to return to the Main screen.
18. Obtain two plastic tubs. Set Tub 1 (the smaller of the two if they are different sizes) on top of a textbook. Place Tub 2 on the table next to Tub 1 as shown in Figure 2.
19. Pour 1 liter of tap water into Tub 1. Pour 1 liter of saltwater into Tub 2.
20. Secure the Conductivity Probe to a ring stand using a test tube clamp as shown in Figure 4.
21. Gather a piece of plastic tubing and a plastic syringe. Connect the syringe to one end of the tubing.
22. Place the free end of the tubing under the water in Tub 1. Pull back the plunger of the syringe until you have drawn 5 mL of water into the syringe. Place the syringe under the water in Tub 2.
23. Tape the tubing in place on the edges of the tubs with masking tape.
24. Position the Conductivity Probe in Tub 2 so that it is 5 cm from the end of the tubing. Make sure the hole on the probe is fully submerged.
Figure 5
25. Tap to begin data collection.
26.Carefully, under water, disconnect the syringe from the tubing. At this point water should be flowing out of Tub 1 and into Tub 2. The freshwater should be flowing into the tub filled with saltwater in much the same way that freshwater from a river flows into the ocean. Note: Do not move the probe or tubing during data collection.
27. Data collection will stop after 600 seconds (10 minutes). Examine the graph and determine the final salinity.
a. To examine the data pairs on the displayed graph, tap or any data point.
Figure 4
b. Move the examine line to the last point on the graph and record the final salinity in the data table.
28. Sketch or print copies of the graph as directed by your teacher.
DATA
Part I Part II
Pan 1
Light
Pan 2
No Light
Freshwater
River
Initial salinity (mg/L)
Final salinity (mg/L)
Salinity change (mg/L)
Initial salinity (ppt)
Final salinity (ppt)
Salinity change (ppt)
PROCESSING THE DATA
1. In the space provided in the data table, subtract to find the salinity changes.
2. Salinity is most commonly reported in units of ppt (parts per thousand). To convert your mg/L values into ppt values, divide them by 1000. Record the results in the data table.
3. Discuss how the salinity changed in Part I. Did you answer the Pre-Lab Question correctly?
4. Discuss how the salinity changed in Part II. Did you answer the Pre-Lab Question correctly?
5. Aquatic animals cannot survive in an environment where the salinity levels fluctuate greatly.
Explain why the salinity levels in the ocean stay relatively constant.
6. Provide a geographical example of the process that took place in Part I.
7. Provide a geographical example of the process that took place in Part II.
EXTENSIONS
1. Find a map of world-wide ocean salinities. Select two regions and explain why they are more or less saline than the 35 ppt average.
2. Obtain some actual ocean water and test its salinity. Hint: It will have to be diluted first.
Other suggestions-
Beach Replenishment Key Criteria:
Goal:
Your challenge is to convince the city council
of Virginia Beach to either continue or
discontinue current practices of replenishing
sand on the area’s beaches.
Role:
You are a concerned citizen and taxpayer in
Virginia Beach.
Audience:
You need to convince the city council to vote
for or against current practices depending upon
your views.
Situation:
The challenge involves balancing residents’ and
business owners’ concerns with the concerns of
taxpayers who are not directly affected by
beach erosion.
Product Performance and Purpose:
You will create a letter to the editor to be posted
in the newspaper or a speech to be presented to
the city council.
Standards and Criteria for Success:
Your letter/speech must include:
a. Relevant data on costs to taxpayers.
b. Relevant data on advantages and
disadvantages of replenishing sand on
beaches.
c. Information on current practices to
retain sand on beaches.
d. Answers to questions such as:
How well does beach replenishment work?
Who benefits from beach replenishment?
Does beach replenishment harm the
environment?
Who pays for beach replenishment?
Suggested Assessment Evidence Pre-Assessment
K-W-L on topics of oceanography: physical, chemical, geological, and biological.
Teacher-generated pretest on topics of oceanography.
On-going Assessment
The following questions could be used throughout the unit for discussion/ongoing assessment:
How are the movements of the Earth, moon, and sun related to ocean tides?
What causes the phases of the moon?
How are seasons caused?
How does the moon create tides?
Why do tides occur fifty minutes later each day?
What are spring tides, and how and when do they occur?
What are neap tides, and how and when do they occur?
What is tidal range?
How are most waves formed?
What two factors affect the height of wind-formed waves?
What are the parts of a basic wave?
What causes breakers to form?
How are currents formed?
What is the general circulation pattern of ocean currents north and south of the
equator?
How do wind belts affect ocean currents?
Where is the Gulf Stream?
How do ice caps affect sea level?
What physical, chemical, and biological effects does upwelling have on a surrounding
area?
What is the effect of:
increased temperature on the salinity of ocean water to hold dissolved salts?
the lowering of temperature of seawater on the density of seawater?
increased salinity on the physical properties of water?
What are the causes of the bathymetric features that are common to all ocean basins?
How can sea floor profiles be derived from echo sounding?
What are continental shelves?
What is a continental slope?
What are submarine canyons?
What is the continental rise?
What are abyssal plains?
How are these features caused?
What is a seamount?
How are seamounts in the middle of plates thought to have originated?
What is a guyot?
What is the mid-ocean ridge and what is its composition?
What happens to the lithospheric plate at mid-ocean ridges?
What is sonar and how is it used to create bathymetric maps?
Summative Assessment
Quizzes, tests, and projects
Suggested Learning Activities and Resources
For Topic: The Oceans
Text: Holt Earth Science
The Water Planet p.471
Formation of Earth’s Oceans, p.690
TR 93 – The Global Ocean
TE Using the Figure Global Oceans, p.471
For Topic: Properties of Water
Text: Holt Earth Science
Properties of Ocean Water, pp.493-500
TR 96 – Dissolved Gases in the Ocean
TR 97 – Average Surface Salinity of the Global Ocean
TR 100 – Sea Surface temperatures in August
CD Interactive Tutor Seawater
CL Activity TE p. 393
MiniLab: What is the chemical composition of seawater? p. 394
Lab 15.1 Ocean Surface Temperatures, LM, p. 113
GeoLab Modeling Water
Masses, p. 406
Assessment Performance, TE p. 398
Lab 16.1: Changes in Sea Level, LM, p. 121
For Topic: Physical Oceanography
SFT 46 – Crowded Waters
Lab 15.2 Making Waves, LM, p. 117
TT 45
Problem Solving Lab: Analyze a Tidal Record, p. 401
For Topic: Geological Oceanography
SFT 48 – Seeing the Seafloor
TT 47
Problem Solving Lab: Comparing Continental Elevations to Ocean Depths, p. 423
TT 43
TT 48, 49, and TT 50 – Types of Plate Boundaries
Discovery Lab: Composition of Chalk, p. 413
MiniLab: How fast do sediment grains sink? p. 428
GeoLab: Identifying Coastal Landforms, p. 430
TT 46
For Topic: Biological Oceanography
Lab 16.2 Observing Brine Shrimp, LM, p. 125
Exploring Environmental Problems: How Might Global Warming Affect Sea Level? p. 13
Science and the Environment:
Deep Sea Dangler, p. 432
Lab 21.1 Analysis of a Climate-Change Time Line Using Planktonic Foraminifera, LM, p. 165
Lab 27.2: Algal Blooms, LM, p. 213
For Topic: Man’s Interactions with the Marine Environment
Lab 23.2: Searching for Oil With Microfossils, LM, p.181
Lab 27.1: Cleaning Up Oil Spills, LM, p. 209
Mapping GeoLab: Pinpointing a Source of Pollution, p. 734