Abstract

Objective

In this experiment you will test the effects of the heavy metal copper (Cu) on an aquatic environment containing algae, worms, fish, and plants.

Introduction

You might know that lead can be toxic, and that you can get lead poisoning from eating or inhaling old paint dust. Lead is called a heavy metal, and there are other sources of heavy metals that can be toxic, too. Silver, copper, mercury, nickel, cadmium, and chromium are all heavy metals that can be toxic in certain environments.

"Toxic metals, including "heavy metals," are individual metals and metal compounds that have been shown to negatively affect people's health. In very small amounts many of these metals are necessary to support life. However, in larger amounts, they become toxic. They may build up in biological systems and become a significant health hazard." (OSHA, 2004)

In this experiment you will find out if one common heavy metal, copper (Cu), can be toxic to an aquatic environment. You will use copper because it is one of the heavy metals that is easy to find and it is not very toxic to humans. You will use copper sulfate as a source of copper that is soluble, meaning it will dissolve in water. A recommended source for soluble copper sulfate is in aquarium products designed to treat infestations. One such product is called "Had-A-Snail" and contains a 3.8% solution of copper sulfate pentahydrate, or 1.61% copper ion in solution.

The amount of an ion in solution is often measured in parts per million (ppm). This means that if there is 1 ppm ion in solution, then there is 1 milligram (mg) present in each liter (L) of solution. Heavy metals release free ions in solution that are very potent, and can cause an effect at very low doses, less than 0.5 ppm! How do you calculate the amount of ion in ppm from a solution where the concentration of ion is measured in percent, like Had-A-Snail?

First, start by reading the manufacturers instructions. To use Had-A-Snail you add 1 drop per gallon of water, but you will need to convert these units to the metric system. This means that 1 drop will convert to 1/20th of a milliliter (mL) which is the same as 0.05 mL, and that 1 gallon will convert to 3.785L which is the same as 3785 mL. Had-A-Snail provides 1.61% copper ion in solution from 3.8% copper sulfate pentahydrate. So the calculation for the amount of copper in the diluted 1 gallon solution is

The product guidelines will give you a baseline, or a place to start, for deciding how much copper to use in each of your experimental environments. Once you know your baseline, then you will add increasing amounts of copper to a series of experimental aquatic environments. You will need to calculate the amount of copper in parts per million (ppm) for each experimental environment. Then, you will add a number of aquatic organisms to each environment. Each aquatic environment will be a mixture of algae, plants, worms, and fish. How will adding copper affect the organisms in each environment?

Terms, Concepts, and Questions to Start Background Research

To do this type of experiment you should know what the following terms mean. Have an adult help you search the internet, or take you to your local library to find out more!

• heavy metals and their sources
  • copper (coins, pipes, wiring, fungicide, pesticide)
  • lead (old paint, fishing weights)
  • nickel (coins, batteries)
  • mercury (thermometers, fluorescent light tubes)
  • arsenic (pesticides and rodenticides)
  • cadmium (batteries)
  • chromium (chrome plating, batteries, toner, paint)
• environmental toxicity
• aquatic environments
• soluble
• insoluble

• How will soluble copper affect an aquatic ecosystem?
• Will all of the organisms be affected similarly or differently?
• How much copper will cause an effect?

Bibliography

• This project was adapted from the Duckweed Bio-Assay protocol from Cornell University:
  EIP, Date unknown. "Assessing Toxic Risk: Student Edition," Environmental Inquiry Program (EIP), Cornell University [accessed July 3, 2006]
  http://ei.cornell.edu/teacher/pdf/ATR/Protocol2.pdf
• Here is a resource on the uses of copper in aquariums:
  Aukes, B., 2006. "All About Copper Sulfate," FishyFarmacy.com [accessed July 3, 2006]
  http://www.fishyfarmacy.com/Q&A/all_about_copper.html
• Damgaard, M., 2003. "Copper and Your Health." Wisconsin Department of Natural Resources [accessed October 5, 2006]
  http://www.dnr.state.wi.us/org/water/dwg/copper.htm
• OSHA, 2004. "Safety and Health Topics: Toxic Metals." U.S. Dept. of Labor, Occupational Safety and Health (OSHA) [accessed July 3, 2006]
  http://www.osha.gov/SLTC/metalsheavy/index.html
• At this site, you can find out the toxicity of different chemical compounds:
  Habeck, M., 2006. "Toxics," Eco-USA.net [accessed July 3, 2006]
  http://www.eco-usa.net/toxics/index.shtml
• Heavy metals are often used in agriculture as pesticides. Learn more about pesticide use and ecotoxicity from the Pesticide Action Network (PAN):
  PAN, 2006. "The PAN Pesticides Database," Pesticide Action Network (PAN), San Francisco, CA. [accessed July 3, 2006]
  http://www.pesticideinfo.org/Index.html

Materials and Equipment

• 1 3/4 oz. bottle of "Had-A-Snail" - a copper sulfate pentahydrate solution for treatment of snail infested aquariums, available at pet stores selling aquarium supplies.
  NOTE: There are many other common sources of soluble copper sulfate in liquid form (available at pet stores in the aquarium section for treating fish parasites) and granular form (available at a nursery or hardware store for treating plants for pests and fungal infections). Using these other products will alter all of the suggested amounts in this project. You will need to read the manufacturers recommendations and calculate the amount of product to use for your experiment.
• 6 empty recycled 1 gallon milk containers, cleaned and rinsed thoroughly
• 6 large, reusable plastic containers with lids (6 cups / 48 oz, e.g. Glad or Zip-lock)
• permanent marker for labeling
• aquatic organisms: (should pick at least 2 plants and 2 animals)
  • small, cheap fish (minnows, feeder fish, or goldfish from pet shop or bait shop)
  • small pond snails (pond or aquarium supply store)
  • water fleas (Daphnia, available at aquarium supply stores)
  • live tubifex (available at aquarium supply stores, bait shops, or found in pond bottoms)
  • aquatic plants like duckweed or elodea (available at aquarium supply stores, ponds, or nurseries)
  • algae (spirulina, available at aquarium supply stores)

Experimental Procedure

1. Rinse each container thoroughly with water. Do not use soap because it can coat the plastic container and may be harmful to the organisms in your experiment.
2. Prepare the copper solutions for each container, using one milk jug for each experimental group. Use the permanent marker to label each milk jug with the amount of copper ion in ppm. Add the corresponding amount of distilled water and copper sulfate pentahydrate (Had-A-Snail) according to the table below:

   Water (mL)	Drops of Concentrated Copper Sulfate Solution (Had-A-Snail)	Total Copper Ion in Solution (ppm)
   1 gallon	0	0 ppm
   1 gallon	1	0.2 ppm
   1 gallon	2	0.4 ppm
   1 gallon	3	0.6 ppm
   1 gallon	4	0.8 ppm
   1 gallon	5	1.0 ppm

3. Here are some important things to consider when mixing your solutions:
   • Be sure to have one container that only has water as a control.
   • Use bottled water, not tap water, because it may contain harmful chemicals like chlorine or chloramine.
   • Use caution when using the concentrated copper solution. Add the concentrated solution slowly, one drop at a time.
   • Finally, label each container with a permanent marker.
4. Use the gallon solutions to fill your containers with lids. Label each container with the same label as the solution you fill it with (0 ppm, 0.2 ppm, 0.4 ppm, etc).
5. Evenly distribute the organisms into each container, being sure to add a mixture of plants (algae, duckweed, elodea) and animals (aquatic worms, snails, and small crustaceans).
6. Observe the animals and write down observations in a data table. Continue your observations for a few hours, or overnight if necessary. For each observation, count the number of organisms that are still alive for each different type. This is called a viability assay, because you are counting the number of things that are viable, or still living.

   Total Copper Ion in Solution (ppm)	Observations (Viability, Appearance, Etc...)
   0 ppm
   0.2 ppm
   0.4 ppm
   0.6 ppm
   0.8 ppm
   1.0 ppm

7. Make a graph of your results. On the left side (Y-axis) of the graph, make a viability scale by graphing the number of living organisms of each type. On the bottom (X-axis) of the graph write the amount of copper sulfate in each solution. Then make a line graph for each type of organism in your study. Did they respond similarly or differently to the copper in your environments? Which amounts are toxic? Which organisms are the most sensitive or the most resilient to the copper?

Variations

• Some water plants can remove contaminating heavy metals from aquatic environments. Others are poisoned by them. Do an experiment comparing different species of aquatic plants for this ability. Use a copper test kit to test the water each day after the plants have been added.
• We used copper sulfate because it is highly soluble. Can other sources of copper be a problem? Try other sources of elemental copper, like pipes, wires, and metal sheets. Also try other metal products that are weak toxins, like aluminum (foil, cans) or zinc (coins, wires). Are any of these common sources of metals toxic to aquatic life? It is important not to do experiments with lead or mercury, because they can be very toxic and cause developmental defects in children.
• Try these other Science Buddies experiments to test the effects of toxins on aquatic environments:
  • Acid Rain and Aquatic Life
  • Something's Fishy About That Fertilizer

• For more science project ideas in this area of science, see Environmental Science Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies

Last edit date: 2006-10-12 21:30:00