Jun. 11, 2010

Testing The Waters

by Austen Saltz

Think oysters are good on the half shell? They may be even better whole. Oysters can restore marine habitats by cleaning water, creating homes for other sea life and preventing coastal erosion. But oyster populations around the world have declined, experts say. Find out how scientists in New York are working to replenish oyster populations in the waters around the city.
Grade Level: 6th – 8th grade
Subject Matter: Life Science
Marine science is a very broad and diverse field, covering the biology, chemistry and physics of the oceans and how these areas of ocean science relate to one another. Ocean scientists may study marine biology, coastline ecology, effects of water pollution, and more.
In this activity, students will become marine scientists who focus on water quality and possible sources of contamination that may be found in water. Using an ammonia water testing kit, students will follow scientific procedure for determining the level of ammonia in each water sample, and discuss how this gas can affect the health of organisms living in marine or freshwater environments.
Activity Materials
  • Ammonia freshwater and saltwater testing kit (available at any pet store)
  • Bottled water
  • Window cleaner
  • Water from an aquarium
  • Water from a pond, river, stream, or other local source of freshwater
  • Water from a salt marsh or an estuary, if possible
  • Seawater, if possible
  • Small plastic cups
  • Nitrogen: a colorless, odorless gas that is vital for living organisms.
  • Nitrogen cycle: the series of processes by which nitrogen is converted from an atmospheric gas to nitrogen compounds in soil and living organisms, then reconverted to a gas.
  • Ammonia: a colorless gas that is highly soluble in water.
  • Control sample: a baseline or standard sample, used to help analyze data.
  • Field sample: a sample that is collected outside of a laboratory.
  • Parameter: a measurable quantity
  • Estuary: A place where a freshwater river or stream flows into the ocean, mixing with the seawater. A wide variety of birds, fish, and other wildlife make estuaries their home
What To Do
Prep: Collect and prepare the control and field water samples by pouring each of the following into small plastic cups. Make sure to label each water sample according to the contents or source. This activity can be done solely with freshwater samples if seawater is inaccessible.
  • Control water samples – one for each student:
  • Bottled water
  • Bottled water and window cleaner mixture (1:1 ratio)
  • Field water samples – one for each student:
  • Water from an aquarium
  • Freshwater from a pond, river, stream or similar source
  • Water from a salt marsh or an estuary, if possible
  • Seawater, if possible
1. Begin the lesson by having students watch the Science Friday video, “Oysters – Not Just For Eating.” Begin a discussion with the students on the definition of marine science and the variety of things that marine scientists investigate. Why do marine scientists study water quality? Tell students that they will play the role of marine scientists by testing a number of water samples for concentrations of ammonia.
2. Ask students to discuss their personal experiences with ammonia and how it is used. What are the different ways that ammonia is produced? How does ammonia get into our environment?
3. Hand out the ammonia testing kit and review instructions on how to use the kit. Make sure students understand how to read the results using the indicator charts provided with the kit.
Activity 1: Testing Control Samples
1. Hand out the labeled control samples to each student. Inform students that these samples are the control samples that will be tested in order to test the validity of the test kit, and to familiarize students on how to perform the procedure.
2. Ask students to predict what the results should be for the sample labeled “Bottled Water” and the sample labeled “Bottled Water with Window Cleaner.” What is one of the main ingredients in window cleaner?
3. Have students test the two water samples and record the data on a chart. Compare their results to their predictions. What do they think would happen to any living organisms that lived in a lake or ocean composed of the water sample with window cleaner?
Activity 2: Testing Field Samples
1. Hand out the field samples so that each student has one of each sample. Review the sources of each water sample (lake, pond, etc.) and the various types of living organisms that typically live there. Ask students to describe how high levels of ammonia can affect these organisms.
2. Have students test the field samples and record their data on the chart. Have students compare their results with each other and with the results from the control samples. Were there any differences in the results? If so, what variables could have caused these differences?
3. Discuss the water quality of each of the samples from the field. What would be further actions to take if the results indicated high levels of ammonia in any of the field water samples?
What’s Happening?
Ammonia is naturally produced by excretions of living organisms, and as a byproduct of decaying organic matter such as plants and grass clippings. Ammonia is an important part of the nitrogen cycle, in which waste is broken down by bacteria into compounds that can be used for growth by other living organisms. Industrial and chemical companies also manufacture ammonia for detergents and fertilizers.
Ammonia levels in water can increase due to natural processes, such as an overabundance of organisms producing waste in a contained ecosystem, or human activities, such as dumping industrial or biological waste into the natural environment. Even low co
There are numerous parameters that scientists use to measure the health of marine or freshwater environments. Besides testing for ammonia levels, scientists may test for other factors -- dissolved oxygen levels, salinity, pH, turbidity, temperature, etc. -- in order to determine whether the conditions of the water are ideal for organisms that live in the water, as well as for those that depend on it as a source of drinking water.
Topics for Science Class Discussion
  • What is the pure form of ammonia? What are the ammonia compounds created through bacterial decomposition?
  • Why is it important to continuously test an aquarium in your home for ammonia levels as opposed to the ocean?
  • Explain all the parts of the nitrogen cycle. Where can you see the nitrogen cycle in action?
  • Why is it important to test marine or freshwater environments for other factors such as salinity, pH, turbidity (having sediment or foreign particles stirred up or suspended in it) and temperature?
Extended Activities and Links
  • Give students the opportunity to collect their own water samples from other water sources in their community, and test their field samples for concentrations of ammonia.
  • Have students research if there are any environmental issues with marine or freshwater habitats in their community. Students can become citizen scientists to develop scientific solutions or become student activists and create a campaign to promote freshwater or marine conservation.
  • Challenge students to research, design and maintain a living freshwater or saltwater aquarium in the classroom.
  • Try these ocean-related science activities from Jean-Michel Cousteau Ocean Adventures educator resources
About Austen Saltz


