Name
Environmental Science—Mrs. Machut
Eutrophication Lab
Eutrophication is a process in which bodies of water, such as ponds, lakes, streams, and rivers
become rich in nutrients and initially experience increased plant growth. But as the plants die
and decompose, oxygen is used up and the body of water becomes unable to support aquatic
life. It is a natural process that usually occurs over many years, but can be accelerated by human
activities. When caused by human activities, this process is known as cultural eutrophication.
Cultural eutrophication is occurring in some areas due to runoff of fertilizers, dumping of
sewage, and other sources of water pollution. A common result of cultural eutrophication is a
rapid increase algae growth, known as an algal bloom. The water becomes covered with mats of
green, brown, or red algae. As the algae dies, microorganisms decompose the remains,
depleting oxygen in the water and killing fish and other aquatic organisms sensitive to low
oxygen levels. Some bodies of water are more prone to experience the adverse effects of cultural
eutrophication. In this lab, you will investigate the effects of excess nutrients on water quality in
lakes and rivers and predict which body of water is more likely to be adversely affected by
cultural eutrophication.
OBJECTIVES
Investigate the effects of excess nutrients on water quality in lakes and rivers.
Predict which type of body of water is more adversely affected by cultural eutrophication.
PRE LAB QUESTIONS
1. How do excess nutrients (fertilizers) affect water quality in lakes and rivers?
2. Are lakes or rivers more susceptible to adverse effects from excess nutrients? Why?
QUESTION:
How does adding fertilizer effect algae growth in an aquarium?
FORM A HYPOTHESIS
3. Form a hypothesis that answers your question. (If, then, because..)
TEST THE HYPOTHESIS:
4. Fill each jar half full with distilled water. Then add the same amount of pond water to each
jar. Label one jar “control” (no fertilizer), one as “excess fertilizer 1” and one as “excess
fertilizer 2.” To jar 1 add _______ of fertilizer, and to jar 2 add _______ of fertilizer. Stir the
contents of each jar thoroughly to dissolve all fertilizer. Place under grow light or close to a
sunny window.
5. Observe all jars at least every other day for the next two weeks. Note changes in color,
turbidity (clarity), smell of water. Test pH levels of water in each jar. Enter your data on the
Eutrophication Lab Data Chart.
6. Record your observations in the data table below
Eutrophication Lab Observations Over a 2 Week Period
Day
Day 2
Day 4
Day 6
Day 8
Day 10
Day 12
Day 14
pH
Date
Observations
Drawing
ANALYZE THE RESULTS
1. What is the purpose of the control?
2. How does excess fertilizer affect water quality in the aquariums?
3. Where does the alga growing in each aquarium come from?
DRAW CONCLUSIONS
1. Making Predictions Predict what might happen to a lake situated close to a golf course.
2. Evaluating Models How do you think this model compares to real-life processes that occur
in lakes and streams that receive nutrient-rich runoff or pollution?
3. Write a Conclusion for your data using the proper format.