Lake and Ocean Circulation
Prof. Tina M. Niemi
UMKC –Geosciences
July 18-20, 2007
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Lesson #1 - Sampling on a Lake
Materials Needed:
 Map
 thermometer
 Van Dorn water sampler
 pH meter
 sample bottles
 conductivity meter
 marker
 5-in1 Test strips
 GPS units
 Nitrate/nitrites test strips
 Hach dissolved oxygen kit
For these two lessons, we will meet at the Gopher Lake parking lot at James
A. Reed Memorial Wildlife Area in Lee’s Summit, MO. The purpose of this
field trip is to investigate the stratification of a lake, the changes in water
chemistry and temperature with depth, and explore the implications of these
differences on water circulation and aquatic life.
We will utilize the boats provided by the park and a Van Dorn-type water
sampler to collect the lake water at various water depths. The water samples
will be collected in bottles. Once onshore, we will use the test kits to
determine various chemical properties of the water.
The figure below shows the technique for sampling lake water at various
depths from a boat.
Source: http://esp.cr.usgs.gov/info/lacs/hohsamp.htm
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Measuring layers in a lake
Quoted from the U.S. Geological Survey
(http://esp.cr.usgs.gov/info/lacs/hohsamp.htm)
“Lake and ocean waters tend to form density layers based on differences in
temperature, salinity and amount of suspended particles in the water. Layers
of different density don't mix unless an outside force (such as a strong wind)
stirs them. This kind of stratification (layering) reduces the mixing of
oxygen-rich surface waters and nutrient-rich bottom water. Thus, water at
different depths will have different chemistries and abilities to support plant
and animal life.”
“By studying water chemistry differences within the lake we learn how algal
blooms, increases in precipitation and nutrient concentrations eventually
affect the sediment chemistry. This information guides our interpretations of
past changes.”
“Water samples at specific depths are collected using van Dorn or
Kemmerer-style bottles. The bottle is an open tube with spring-loaded end
caps. The bottle is lowered to a particular depth and sloshed around gently
(to fill the tube with water from that depth). Then a weight, called a
messenger, is sent down the line holding the tube. The weight hits a spring
mechanism, allowing the end caps to spring shut.”
Lesson Plans: Water on the Web
http://waterontheweb.org/curricula/bs/teacher.html
Procedure:
1) Load sampling equipment in boats.
2) Put life vests on, and review Safety Instructions.
3) Row field team to a sampling site on the lake.
4) Take a GPS reading of your location and record it on the data sheet.
5) Prepare the van Dorn sampler, and label the first sample bottle.
6) Throw the water sampler into the water to the desired depth trigger the
end to collect the sample.
7) Haul the sampler back into the boat, and transfer the water sample into
the marked bottle.
8) Repeat the procedure until all five water samples have been recovered.
Collect water samples from:
a) Surface water
b) water from one meter water depth
c) water from two meter water depth
d) water the bottom
e) water from midway between the bottom to the surface
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Lesson #2 - Thermocline and Water Chemistry
Team Members:________________________________________________
Date: ______________ GPS Site Sampling Location:__________________
Site Description:________________________________________________
_____________________________________________________________
Weather Conditions:_____________________________________________
Water Depth
Water Temperature
DO, mg/L
% Saturation
Conductivity
Nitrite/Nitrate (ppm)
5-in1
Total Chlorine (ppm)
Free Chlorine (ppm)
Total hardness (ppm)
Total alkalinity (ppm)
pH
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DIRECTIONS FOR WATER TESTS
DISSOLVED OXYGEN [PPM]
1) Pour approximately 100 ml of sample SOL-DO into a beaker.
2) Obtain the temperature of the sample using the pocket thermometer. Mark
the temperature on the "Determining Percent Saturation" - Handout
3) From the Dissolved Oxygen kit remove the round bottle with the glass
stopper.
4) Fill bottle with SOL-DO.
5) Incline bottle slightly and quickly insert stopper. DO NOT TRAP ANY AIR
BUBBLES IN THE BOTTLE. If you do, your test will fail later and you will have
to start over.
6) Open one Dissolved Oxygen 1 Reagent Powder Pillow and one Dissolved
Oxygen 2 Reagent Pillow.
7) Remove stopper and add both pillows to the sample water.
8) Replace the stopper again by adding a little sample solution and using the
technique in step 4.
9) Gripping the bottle and stopper firmly, carefully shake it vigorously (do not
break the bottle!!) to mix the sample water and the reagents. A flocculent
precipitate (floc) should begin to form. If oxygen is present, the precipitate
will be a brown-orange color.
o Allow the sample to stand until the floc has settled halfway in the
bottle (use the marked line at the bottle), leaving the upper half of the
sample clear.
o Shake the sample again, and again let it stand until the upper half of
the sample is clear.
o Open one Dissolved Oxygen 3 Reagent Powder Pillow. Remove the
stopper from the bottle and add the contents of the pillow. Carefully
place the stopper back on the bottle.
o Shake the sample water and reagent to mix. The floc will dissolve
completely and a yellow color will develop if oxygen is present.
10)
Fill the small measuring tube (full) of the prepared sample.
11)
Pour the measured sample into the square mixing bottle.
o Add Sodium Thiosulfate Standard Solution. ADD ONE DROP AT A
TIME. Swirl the mixture around in the bottle after each drop. Count
each drop as it is added. Continue adding drops until the sample
changes from yellow to colorless.
o Each drop used is equal to 1 ppm of dissolved oxygen. Mark the
amount of drops on the "Determining Percent Saturation" - Handout
o Use information on the attached "Determining Percent Saturation" –
Handout to determine the amount of DO in the sample.
12)
Record the value on the %Saturation Graph.
13)
Pour used solution into waste water bottle!!
14)
Rinse DO bottles and stopper with distilled water and return to the kit.
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Dissolved Oxygen Percent Saturation
Percent Saturation is the amount of oxygen dissolved in the water sample
compared to the maximum amount that could be present at the same temperature.
For example, water is said to be 100% saturated if it contains the maximum
amount of oxygen at that temperature. A water sample that is 50% saturated only
has half the amount of oxygen that it could potentially hold at that temperature.
Sometimes water can become supersaturated with oxygen because of rapidly
tumbling water. This usually lasts for a short period of time but can be harmful to
fish and other aquatic organisms. DO Percent Saturation values of 80-120% are
considered to be excellent and values less than 60% or over 125% are considered
to be poor.
Determining % Saturation - The "quick and easy" - Method
For a quick and easy determination of the percent saturation value of dissolved
oxygen at a given temperature, use the saturation chart below. Pair up the mg/L of
dissolved oxygen you measured and the temperature of water in degrees C. Draw a
straight line between temperature and mg/L of dissolved oxygen. The percent
saturation is the value where the line intercepts the saturation scale. Streams with
a saturation value of 90% or above are considered healthy.
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ELECTRICAL CONDUCTIVITY [µS]
1) Remove protective cap and turn unit on by sliding the on/off switch.
2) Immerse the sensor-end of the unit into the sample. Make sure sensors are
completely submerged.
3) Wait for the display to stabilize.
4) Multiply the stabilized number by 10 and record.
5) Rinse off the sensor-end of meter with distilled water.
6) Turn the unit off and replace cap.
7) Return sample to correct SOL bottle.
NITRATE/NITRITE [PPM]
1) Dip a single strip into sample water for 1 second and remove. DO NOT
SHAKE OFF EXCESS WATER.
2) Hold the strip level, with pad side up, for 30 seconds.
3) Compare the NITRITE test pad to the color chart on side of bottle.
4) Record the value
5) At 60 seconds, compare the NITRATE test pad to the color chart.
6) Record the value.
7) Dispose of test strip in waste basket, and replace lid on test strip bottle.
8) Dispose of used sample water in bottle labeled WASTE WATER.
1)
2)
3)
4)
5)
6)
7)
5-IN-1 TEST:
TOTAL CHLORINE [PPM], FREE CHLORINE [PPM], TOTAL HARDNESS [PPM],
TOTAL ALKALINITY [PPM], PH
Dip one strip into the sample water for 1 second. DO NOT SHAKE OFF
EXCESS WATER.
Hold strip level for 30 seconds.
Compare TOTAL HARDNESS, TOTAL ALKALINITY and pH pads to color chart
on side of bottle.
Record these values
Dip strip into the sample water again and move back and forth for 30
seconds.
Compare CHLORINE pad to color chart.
Record data, dispose of strip, return cap to bottle and dispose of waste water
into the sink.
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Graph your data with water depth on the y-axis and other variables on the
x-axis:
1. At what depth is the thermocline?
2. What layer contained the most dissolved oxygen?
3. Describe the variations in depth of other chemical properties of the lake
water.
4. What is a “Dead Zone”? How do they form?
5. What is eutrophication?
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Concept Mapping Terms:
Temperature, dissolved oxygen, thermocline, nitrates, eutrophication,
stratification, nutrient-rich water, oxygen-rich water, conductivity, total
dissolved solids, and other terms as needed
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Lesson #3 - Ocean Circulation
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Exploration: Water in the ocean (Adapted from DiscoverySchool.com)
http://school.discovery.com/lessonplans/programs/oceans/index.html
Materials needed:
 Globe or map
 Food coloring
 Ice cube tray
 Aquarium, or large clear
plastic rectangular
container
 Hot plate






Pan for boiling water
Table salt
Balance
Thermometer
2 Petri dishes
Stirring rod
Examine a globe and answer the following questions.
How many oceans are there and how are they connected?
What is the temperature of the ocean?
What temperature is at the bottom of the ocean?
How does water in the ocean move?
Why does ocean water circulate?
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Activity #1: Variations in Water Temperature
Preparation: The day before the experiment--Dye water with various colors
(blue, red, and green work best) using food coloring and freeze in ice cube
trays.
1. Fill the aquarium with warm tap water
2. Place a blue and a red ice cube at each end of the aquarium
3. Describe what happens.
Activity #2: Evaporation
Preparation: Place one Petri dish of tap water and a second Petri dish of salt
water on the window ledge and watch it over the course of 1 to 2 weeks.
Describe what you see.
Activity #3: Variations in Salinity
1. Make the saltwater
 Measuring 17.5 g of salt on the balance
 Pour salt into an empty dry 500 mL cylinder
 Fill the cylinder to the 500 mL mark with Distilled Water
 Stir until salt dissolves
 Add food coloring
2. Fill the aquarium and a 500 mL graduated cylinder with warm tap water
3. Determine the temperature of the water
4. Slowly add the dyed water into the aquarium.
5. Describe what you observe.
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Concept Introduction: Thermohaline Circulation
“The major water masses in the deep ocean are differentiated by their
temperature and salinity. These properties determine their relative densities,
which in turn drive deep thermohaline circulation of the oceans. NADW =
North Atlantic Deep Water. AABW = Antarctic Bottom Water. Modified from
figure courtesy of Dr. Steve Hovan, Indiana University of Pennsylvania.”
1. What is density? Based on your experiments with waters of different
temperatures and salinity, what makes the densest water?
2. Examine the diagram above. Where in the oceans will you find the
densest water?
3. How does the atmosphere interact with the ocean?
4. What is upwelling and downwelling?
Concept Mapping
Density, salinity, evaporation, equator, polar, temperature, density, sodium
chloride, halite, salt, thermohaline circulation, thermocline, upwelling,
downwelling
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Application: El Niño-Southern Oscillation (ENSO)
Goals:
1) Describe El Niño and La Niña. Why are they important?
2) Explain how the ocean and atmosphere interact in the tropical Pacific.
3) Explain how conditions in the tropical Pacific affect climate worldwide.
Procedure:
1. Examine EI Nino!-La Nina! with the slide insert pushed all the way into
the device so that Neutral (normal) Conditions appears in the indentation
along the bottom of the large window. (Note: If La Niña appears when fully
inserted, pull the slide out, flip it to the other side, and reinsert.)
2. Look at the large window. It displays a schematic of the Pacific Ocean
along the equator (greatly exaggerated in the vertical). The scene depicts
the ocean surface with atmosphere above and a vertical cross-section of the
ocean below.
3. Above the large window picture are the atmospheric variables shown at
three longitudinal locations across the equatorial Pacific:
 rainfall,
 surface air pressure, and
 trade wind (direction and magnitude).
4. Below the large window picture are the ocean variables shown at two
longitudinal locations across the equatorial Pacific:
 Surface currents,
 sea surface temperature,
 sea surface height,
 thermocline depth.
5. Use the Slide Card to determine the variations in Neutral, El Niño, and La
Niña conditions and fill out the following charts.
6. According to the values reported in the windows, the highest sea surface
temperatures (SST) during neutral conditions occur in the western tropical
Pacific. Explain why this SST pattern occurs.
7. Explain how upwelling is created along the Eastern tropical Pacific. How
does this affect the weather (SST, pressure, rainfall etc…) in that location?
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Neutral (Normal) Conditions
Western Pacific
Atmosphere
•rainfall
•Air Pressure
•Trade winds
Eastern Pacific
Ocean
•Currents
•SST
•Sea height
•thermocline
El Niño Conditions
Atmosphere
•rainfall
•Air Pressure
•Trade winds
Western Pacific
Eastern Pacific
Western Pacific
Eastern Pacific
Ocean
•Currents
•SST
•Sea height
•thermocline
La Niña Conditions
Atmosphere
•rainfall
•Air Pressure
•Trade winds
Ocean
•Currents
•SST
•Sea height
•thermocline
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8. Changes in SST in the eastern tropical Pacific have implications across the
world. Turn your EI Niño!-La Niña! over. Briefly describe the changes in the
weather across the world for an El Niño episode.
9. Briefly describe the changes in the weather across the world for a La Niña
episode.
The following website shows current SST’s.
http://www.emc.ncep.noaa.gov/research/cmb/sst_analysis/
The EI Nino!-La Nina! slide rules may be purchased through this website:
http://www.ametsoc.org/amsedu/AERA/ed_mats.html
Concept Mapping:
El Niño, La Niña, ENSO, global weather, trade winds, upwelling, equatorial
Pacific, thermocline, SST
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