Aquatic Plants as Natural Biological Filters
In this exercise, students will explore the ability of aquatic plants to act as a natural biological filter of effluent. Testing of aquatic plants uptake of nitrogen will include a controlled experiment involving setups of three 'tanks' (beakers). One tank will contain distilled water, one tank will contain an unknown concentration of NH4Cl and the third tank will contain the sme unknown concentration of NH4Cl and elodea or similar aquatic plant. Students will use a colorimetric ammmonia test kit to record the amount of ammonium over a three to five day period
Objectives
Students will demonstrate the ability of aquatic plants to uptake nitrogen in ammonium form. Students will use a controlled experiment to record and graph the data. Students will also test for proper pH.
Materials
  • Each lab group will receive three small fish tanks (or large beakers)
  • An unknown solution of different concentrations of NH4Cl
  • Ammonium test kits - colorimetric
  • Sprigs of Elodea ( or other aquatic plants
  • pH test paper
  • fact sheet on elodea
Procedure
Each lab group will be given an unknown solution containing either 1.0 ppm, 0.50 ppm or 0.25 ppm of NH4CL and 9 sprigs of elodea or other aquatic plant. Each group will design a controlled experiment to show the uptake of nitrogen by aquatic plants. Colorimetric test kits will be used to measure the amount ammonium in the solutins. pH test paper will be available to test for the acceptable pH for the given aquatic plant which is available on the fact sheet. Studes will record the initial ppm and pH reading. Students are responsible for designing and maintaining a data table for the three to five days of investigation. Using the fact sheet on the aquatic plant, each lab group will decide the correct light and temperature. 
References
What Every Aquarist and Pond Keeeper Should Know About Ammonia Test Kts - www.novalek.com/kpd2.htm
Biological Filtration In Aquariums and Ponds - www.novalek.com/kpd64.htm
Plants and Biological Filtration - www.aquabotanic.com/plants and biological filtration.htm.
 
State Standards
2.5.2- The student will analyze the effects of natural cycles on human activity.
3.2.1- The student will explain processes and the function of related structures found in unicellular and multicellular organisms.
3.2.2- The student will conclude that cells exist within a narrow range of environmental conditions and changes to that environment, either naturally occurring or induced, may cause changes in the metabolic activity of the cell or organism.
3.6.2- The student will investigate a biological issue and be able to defend their position on topics such as animal rights, drug and alcohol abuse, viral diseases (e.g., AIDS), genetic engineering, bioethics, biodiversity, population growth, global sustainability, or origin of life. (NTB)
Lesson Resources