Biocomplexity Lab Activity: Eutrophication · PDF fileBiocomplexity Lab Activity:...

Biocomplexity Lab Activity: Eutrophication Lab Objective: To examine the effects of detergents and fertilizers on aquatic life

Warm Up: Describe algae.

Materials:

1) 50 small jars (10 per class)

2) Pond Water

3) Dissolved Oxygen Kit (bought from Wards Biology)

4) Detergent containing Phosphates

5) Fertilizer in Powder Form

6) Measuring spoons

7) Info Charts (Attached)

8) Eutrophication Notesheet

9) “Eutrophication – What is it?” Article

Background:

Eutrophication is the process by which a body of water, such as a pond, lake, stream or river, has a sudden increase in plant life. The main cause in this increase is plant nutrients, especially nitrogen and phosphorus. When the introduction of these nutrients is due to human activity with detergents and fertilizers, it is called cultural eutrophication.

A direct result of cultural eutrophication is a rapid increase in algae. This is referred to as algal bloom. The increase in algae causes water to become cloudy and it decreases the amount of oxygen in the water. Furthermore, some types of algae release toxic substances into the water. These toxins can be ingested by other aquatic life and enter the food chain. Humans can get food poisoning by eating these organisms.

Aquatic organisms, just like land organisms, need a supply of oxygen to survive. With this algal bloom and decrease in oxygen, the organisms will being to die.

Procedure:

1. Obtain enough pond water for 50 jars

D. Gioffre, Hillsborough Middle School, Hillsborough, NJ 08844 Funded by the National Science Foundation, Biocomplexity in the Environment Program, Award #0120453

2. Follow test kit directions and measure the amount of dissolved oxygen in the pond water.

3. Label the jars 1-10 and fill each jar with pond water (you might want to mix ½ water with ½ pond water).

4. Students will make a hypothesis on the attached worksheet.

5. Put the correct amounts of either fertilizer or detergent in each jar using the amounts listed below.

6. Place all the jars in a sunny location.

7. Make observations daily for 2 weeks on Info Chart.

8. Measure the amount of dissolved oxygen each week on day 7 and day 14.

9. Discuss observations aloud and students write a conclusion.

Follow Up:

Students can graph the results of the dissolved oxygen test on an Excel Chart for homework.

Students can also create lists of other sources of nitrogen and phosphates in everyday items.

Students can create a list of things they can do to stop water pollution.

Assessment:

Review of info chart and observation of participation in Lab Activity.

Review of Excel Graph and lists create for homework.

Jars Treatment 1 Control 2 Control 3 1/8 tsp detergent 4 1/4 tsp detergent 5 3/8 tsp detergent 6 1/2 tsp detergent 7 1/8 tsp detergent 8 1/4 tsp fertilizer 9 3/8 tsp fertilizer 10 1/2 tsp fertilizer


Name _______________________ Date ___________

Eutrophication Note Sheet Eutrophication: _____________________________________________ __________________________________________________________________________________________________________________ Phosphorus: ________________________________________________ __________________________________________________________________________________________________________________ Phosphates: ________________________________________________ __________________________________________________________________________________________________________________ Algal Bloom: _______________________________________________ __________________________________________________________________________________________________________________ Dissolved Oxygen: ___________________________________________ __________________________________________________________________________________________________________________ Direct input source: __________________________________________ __________________________________________________________________________________________________________________ Indirect input source: ________________________________________ __________________________________________________________________________________________________________________ Anoxia: ___________________________________________________ __________________________________________________________________________________________________________________ Hypoxia: __________________________________________________ __________________________________________________________________________________________________________________


Eutrophication

What is it? Eutrophication is the word given to describe the effects of when a water body becomes so rich in nutrients that the natural wildlife is unable to survive. The area becomes swamped with algae and foreign species starving the water body of oxygen.

How has it happened? It is possible that this can happen naturally but it has started happening to such an extent that nature is unable to right itself. With man's intervention this process is happening far to frequently. Two of the possible causes are described below:

• Intensive farming • Sewage disposal

Intensive Farming Since the population of this country is increasing there is need to grow more and more crops. If there were unlimited suitable land then there would be no problem but since there isn't more intensive growing is required. This means that the farmer needs to be able to grow more crops per area than before. This is not possible using the traditional techniques so new ones have to be implemented. One such way is to add chemical fertilizers to aid and speed up growth. This is all very well, the country gets enough food but what about all this fertilizer? These fertilizers are rich in very soluble nitrates, as well as phosphates and potassium so when it rains these are washed over and through the soil into nearby waterways. This is where the problem starts to show. The water body is unable to cope with this excess and the wildlife supported by it begin to die out. It reaches a point where they are no longer able to survive and new less sophisticated life takes over, for instance, algae.

Sewage Disposal Untreated human sewage is a massive form of food supply for decomposing organisms. When sewage is directly pumped into a river or lake it becomes an ideal haven for them. These decomposers use up much of the available oxygen to breakdown the sewage which results in eutrophication taking place.


How can it be Avoided? It can be avoided by the use of more organic fertilizers which are high in nutrients but are natural to the environment. Examples include manure which decomposes slowly so the nutrients are not readily leached away. Proper treatment and breakdown of sewage before it is discharged into a river could prevent eutrophication taking place. Once eutrophication has happened it is very hard to put right so the sooner action is taken to prevent it the better. It is very difficult to implement because farmers want to make a living so need to be able to get the most from their land. Trying to persuade them to use organic fertilizer is the first step away from chemical fertilizers and an end to any more rivers becoming ugly swamps.


Name _______________________ Date ___________

Lab Activity: Eutrophication Lab Hypothesis: _______________________________________________ ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Info Charts Jar 1

Date Observation / / / / / / / / / / / / / / / / / / / / / / / / / / / /


Jar 2

Date Observation / / / / / / / / / / / / / / / / / / / / / / / / / / / / Jar 3



Jar 4




Jar 6




Jar 8




Jar 10

Date Observation / / / / / / / / / / / / / / / / / / / / / / / / / / / / Conclusion: ________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


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