Analysis Questions

ANALYSIS QUESTIONS

Effects of Pollution on a Stream

Refer to Table 1 and Graph 1 as you answer the following questions:

Why was it important to determine the baseline conditions before assessing the effects of the pollutants on the stream?
Describe the shapes of the dissolved O2 and temperature curves for the non-polluted stream.
Describe the shapes of the dissolved O2 and temperature curves for the polluted stream.
Compare the dissolved O2 curves for the non-polluted and polluted streams. Describe any similarities or differences.
Compare the temperature curves for the non-polluted and polluted streams. Describe any similarities or differences.
Describe any changes in the types and location of species living in the non-polluted stream.
Describe any changes in the types and location of species living in the polluted stream. How do they differ from the non-polluted stream?
Based on your data, answer why different species survive in some locations but not others. Cite specific examples. Name organisms and the conditions under which they appear or disappear.
Based on your data, identify species that, by their presence or by their absence, may serve as indicators of polluted water.
What was the minimum distance needed for the stream conditions and species composition to return to normal?

Analysis of Different Pollution Scenarios

Only answer questions below that pertain to the scenario(s) you investigated. Refer to Table 2 and Graph 2 for your supporting data. Refer to Table 1 and Graph 1 for data from the non-polluted stream.

Scenario 1: To grow or not to grow?

Describe the dissolved O2 curves produced by the raw sewage and the treated sewage.
Which pollutant had the greater effect on dissolved O2?
How were the species affected by the different pollutants? How do these effects compare with the results seen in the non-polluted stream?
Does the raw sewage affect the stream significantly? Explain.
Should the council be concerned about increased pollution?

Scenario 2: Did they milk the system?

Describe the dissolved O2 curves produced by the animal wastes and by the milk.
Which pollutant had the greater effect on dissolved O2?
How were the species affected by the different pollutants? How do these effects compare with the results seen in the non-polluted stream?
Is milk a pollutant? Explain.
What caused the fish kill - the animal wastes or the milk? Explain.

Scenario 3: Is dilution the solution to pollution?

Describe the dissolved O2 curves produced by the treated sewage under the two different conditions.
Which condition had the greater effect on dissolved O2?
How were the species affected by the different conditions? How do these effects compare with the results seen in the non-polluted stream?
Describe another experiment you might need to do in order to accurately determine whether or not building the dam is a good idea.
Is dilution the solution to pollution? Explain.

Scenario 4: Are you getting into hot water?

Describe the temperature curves produced by the two different releases of waste water.
Describe the dissolved O2 curves produced by the two different releases of waste water.
Which release had the greater effect on dissolved O2?
How were the species affected by the different conditions? How do these effects compare with the results seen in the non-polluted stream?
Should the power plant be allowed to increase production? Explain.

Applying What You Learned

Rainwater and other runoff that results from people watering their lawns and gardens or washing their cars is carried away by storm sewers that run beneath the streets in many cities and towns. Imagine that you live in a town where all of the storm sewers drain into a stream that runs through the park at the center of town. The members of the local environmental club are worried that the stream is being harmed by pollution in the runoff. Knowing that you have recently studied stream ecology, the members ask you to help them evaluate the health of the stream. How you would evaluate the health of the stream?

Describe how you would determine whether or not the stream was being significantly affected by the runoff.
List specific examples of the types of organisms you might expect to see in a healthy stream.
List specific examples of the types of organisms you might expect to see in a polluted stream.