Lab: Ecosystems in Distress: Oil Spill Cleanup

NAME:______BLOCK:_____DATE:______

Lab: Ecosystems in Distress: Oil Spill Cleanup

Purpose:

Students will learn why an aquatic oil spill is so harmful to birds. They will also be introduced to the problems and the difficulties of trying to clean up an aquatic oil spill on a very small scale. Students can then determine the effectiveness of various methods that could be used to remove oil from the surface of the water. The costs, both environmental and monetary, of each method will also be considered.

Part A: The Effects of an Aquatic Oil Spill on Sea Birds

Materials:

2 Feathers

Cup of water

Cup of water and oil

Procedure:

1. Fill one cup with water and the other cup with water and a few drops of oil.

1. Immerse one feather in the cup of water. Examine it carefully. Write your observations of this feather below.

1. If a bird’s feathers become wet with water, what does the bird instinctively do to dry its feathers?

1. What physical process is responsible for the drying?

1. Predict what will happen if you dip a feather into water and oil.

Hypothesis:

1. Immerse your other feather into the cup of water and oil and examine it carefully. Was your prediction correct? Explain.

1. Birds caught in oil spills are washed with liquid Dawn to remove the oil. Wash the feather with one or two drops of Dawn and rinse well. Record your observations below.

1. Why can’t birds rid their feathers of oil in the same way that they can rid them of water? (tricky question, lets see if you were paying attention in class)

1. How do you think a coat of oil would affect a bird’s ability to fly?

1. How could you test this using the feathers and the water and oil?

1. How do you think a coat of oil would affect a bird’s ability to swim?

1. How could you test this using the feathers and the water and oil?

Part B: Mechanical Clean-Up of an Oil Spill

Materials:

Aluminum pan

Toothpick

Spoon

Pipet

Drinking straws

Oil

String

Liquid detergent

Cotton balls

Paper towels

Sponge

Sphagnum moss

Pine bark shavings

Procedure:

1. Obtain an aluminum pan and fill it halfway with water. This will simulate Prince William Sound, the site of the Exxon Valdez oil spill.

1. Cut a piece of string approximately 35-40 cm long. Make a loop by tying the two cut ends together. Gently float the loop in the center of the pan. This will be your boom (a floating barrier used to contain floating oil and prevent it from spreading over a large area).

1. Add several drops of oil, creating an oil slick, on the surface of the water in the center of the boom.

1. How effective was the boom in preventing the oil from spreading over the entire surface of the water?

1. Use the spoon as a skimmer and try to skim the oil off the surface of the water inside the boom. Dispose of skimmed oil into your waste container. How effective is skimming?

1. Use a toothpick to remove the boom (string loop). Discard both the toothpick and the string in a waste container.

1. As the cleanup from the Exxon Valdez progressed, the waters became rough and choppy due to high winds. Again, add several drops of oil, creating an oil slick, on the surface of the water. If straws are available, gently blow through two of them. Otherwise, one group member can gently blow on the surface of the water. Direct the sir stream across the surface of the oil spill. Using your skimmer, try to clean up the oil spill. Dispose of the skimmed oil a waste container. On the basis of this experiment, is it easier or harder to clean up an oil spill on a windy day? Explain.

1. Add several more drops of oil to the water in the center of the pan.

1. Attempt to clean up the oil spill using each of the absorbent materials in the following chart. Use one item at a time and discard each into a waste container. When necessary, add more oil. Complete Table 1 by indicating how well or poorly each material cleaned up the spill. Use terms such as “poor”, “fair”, and “excellent”.

Table 1

1. Again, add several more drops of oil, creating an oil slick, on the surface of the water. Using the same method as before, create a wind current over the surface of the oil spill. Using your most effective material from the chart above, try to clean up the oil spill. Dispose of your used materials. How did wind affect the clean-up effort using an absorbent?

1. According to your results, which would have been a better mechanical method for cleaning up the Exxon Valdez oil spill, absorbing or skimming? Why?

1. Chemical detergents were not used as a clean-up method. Why do you think this decision was made?

Part C: Bioremedial Clean-Up of an Oil Spill

Materials:

2 Jars

2 Pipets

Penicillium culture

Pseudomonas culture

Oil

Nutrient fertilizer

Distilled water

Microscope slide and coverslip

Procedure:

1. You will now investigate the oil-degrading ability of Penicillium, a special strain of fungus and Pseudomonas.

1. Obtain twojars with a screw cap and place a density indicator strip on each one. Place the strip on the bottom half of each jar. Label it with your name.

1. Fill the jars halfway with distilled water.
2. Using a pipet, add 15-20 drops of oil, just enough to form a thin layer, to simulate the Exxon Valdez oil spill in Prince William Sound. Allow the oil to spread over the whole surface. Dispose of the pipet. Note the original condition and appearance of the refined oil. Record your observations in table 2.

1. Using your thumb and forefinger, sprinkle some nutrient fertilizer over the entire oil layer. Such a fertilizer is used in a real spill situation to enhance microbial growth and oil absorption. It also provides a matrix upon which the microorganisms can degrade the absorbed oil.

1. Obtain another pipet and inoculate one jar drop by drop with 1ml of the Penicillium culture. Try to inoculate as much of the oil slick surface as possible. Dispose of the pipet.

1. Obtain another pipet and inoculate the other jar drop by drop with 1ml of the Pseudomonas culture. Try to inoculate as much of the oil slick surface as possible. Dispose of the pipet.

1. Incubate the jars (with caps loosened a half-turn) at 30ºC or in a warm spot in the laboratory if an incubator is not available.

1. Observe your jars once every 24 hours for 3-4 days. Make careful observations of the general appearance, color and texture of the degrading oil. Observe what is happening to the oil surface over time. Record your observations in table 2.

1. Using the density indicator strips, examine the liquid in each jar for turbidity. To examine for turbidity, place the back of the jar (the part with the density indicator strip) against a white background. Look through the liquid in the jar and note how many of the bars are visible on the back of the tube. The more turbid a sample is, the fewer bars will be visible. Note your observations in table 2.

1. To increase the dissolved oxygen content in the water, use a pipet provided to blow bubbles into the water, once or twice daily. This simulates the wave action in the ocean, which enhances the dissolved oxygen content of the water.

1. At the end of three days, make a wet mount preparation for Penicillium and Pseudomonas, containing a drop of your degradation mixture. View the slide under high magnification. In table 3 describe the appearance of the degrading oil and of the microorganisms and sketch a picture. When finished, dispose of the microscope slides and all other contaminated materials as directed by your teacher.

Table 2

Table 3

PenicilliumPseudomonas

Analysis:

1. Describe what happens to the oil after several days of microbial degradation. Are the microbes breaking up the oil? Can you detect an increase in microbial growth?

1. Is the oil over the surface completely degraded? If not, explain.

1. What is the purpose of the nutrient fertilizer used over the oil spill?

1. What is one advantage of applying a fertilizer to an oil spill? Can you think of a disadvantage?

1. Between the two organisms, were you able to notice any difference in their growth patterns? Explain.

1. Based on the information provided, do you think that the Penicillium and Pseudomonas would be affected by water temperatures? Explain.

1. In an actual oil spill, the conditions are much more variable. Do you think Penicillium and Pseudomonas would follow the floating oil or be dissipated by shifting winds or currents? And if they did eat the oil, would the residue damage marine life?

1. Based on what you learned from performing this exercise, do you believe biological or physical cleanup methods would be more effective in cleaning up an oil spill?