Pass the Salt!!!
Student Handout
NYS Standards Addressed | Salt Learning Experience | Assessment Guide/Rating Scale
Congratulations! You have been selected to serve with a team of scientists that have been hired by the NYS Department of Environmental Conservation and the NYS Department of Transportation to evaluate the impact of road salt on the flora and fauna of the Adirondack Park.
Your taskforce’s research will be used to influence environmental policy in the State of New York. As with any environmental issue there will be a number of risks, costs, benefits and tradeoffs, associated with the conclusion(s) that you will draw from your studies. In order to be an effective member of this team, you will need to familiarize yourself with the issue, learn scientific techniques used to study the impact of the problem, and use critical thinking skills to draw conclusions and to propose solutions.
The basic background information that you have been provided with includes the fact that in 1980, New York State instituted a "bare road" policy regarding snow and ice. This was done to insure that visitors to the 1980 Winter Olympics in Lake Placid would enjoy their stay, The Adirondack Aquatic Institute has identified that this policy is still in effect and that it is having negative effects on lakes and streams in our area (http://www.paulsmiths.edu/aai/salt.html). Others remind us that Homo sapiens are important Adirondack fauna who are placed at a high risk for motor vehicle accidents when road deicing is not made a priority (http://www.saltinstitute.org/30.html). Economic issues, the effectiveness of different road deicing products and the observation that wildlife are attracted to salted highways just like they are attracted to salt licks, are just some of the other realities that factor into this issue.
Your taskforce will be evaluated during each of your formal meetings (lab periods,) and this "on-the-job" evaluation will be multifaceted. You will be graded based on your contributions to this scientific study team, on the quality of your preliminary work and on the scientific paper that you write to communicate your findings. The Task Force Action Plan for your laboratory section, identifies the deadlines that have been established for the completion of each portion of this task. Be sure that you stay on schedule!
Be sure that you or a member of your team has a BRCS Internet license. You will be using the Environmental Inquiry website (http://ei.education.cornell.edu/) hosted by Cornell University throughout this learning experience.
Task Force Action Plan
Pass The Salt
Project Outline: Established Deadlines
Part I. I say….You say….Bioassay!
(An introduction to the usefulness of the bioassay as a quantitative tool for measuring environmental impact.)
A. What is a Bioassay? ____________________
B. Bioassay Basics
1. Procedure for setting up ____________________
2. Data collection plan ____________________
C. Bioassay Analysis ____________________
Part II. Background Check! ____________________
(Do research to familiarize yourself with what is already known about the impact of road salt on Adirondack plants and animals.)
Part III. Salt and Survival ____________________
(Review microscopy techniques and information about diffusion and osmosis, in the context of this learning experience.)
Part IV. Research: Project Design and Implementation ____________________
(Develop a hypothesis regarding the impact of road salt and/or deicing alternatives, design an experiment to test to test the
hypothesis, and write a scientific journal article detailing your findings.)
Part V. Let the research speak ____________________
(Prepare a cover letter designed to influence NYS environmental policy makers to adopt the best management practice that your
research findings suggest would be most appropriate for Lewis County.)
Part I. I Say….You Say….Bioassay!
While we may be tempted to evaluate how toxic a particular chemical is to vegetation by considering the color of a patch of plant material, this type of a result would be qualitative and potentially subjective. Quantitative studies provide us with data that can be analyzed in a manner that is often easier and more reliable. Reference toxicity tests, called bioassays, are conducted in order to quantify how toxic a substance is to a particular organism.
A. What is a Bioassay???
Consult reference resources to learn more about what exactly a bioassay is. You should use printed and electronic materials for this purpose. Respond to the following requests for information:
1. Define the term, "Bioassay."
2. List at least three ways that bioassays are used to insure the health and welfare of people in the United States, today.
3. Brainstorm at least three ways that bioassays can be used to test for the environmental impact of toxins present in the Adirondacks.
4. Record the bibliographical information of at least three sources that you used, to answer the questions above:
B. Bioassay Basics
In the next segment of this lab activity, your team will learn how to conduct a bioassay so that you become comfortable with the technique, and so that you can draw preliminary conclusions regarding the impact of road salt on plants. The following procedure has been adapted directly from the Environmental Inquiry website (http://ei.education.cornell.edu/).
Setup Procedure:
a) Soak lettuce seeds for 20 minutes in a 10% bleach. Then rinse five times. This kills fungal spores that can interfere with seed germination.
b) Place a 7.5-cm paper filter in each of six, 9-cm petri dishes. Label each of the petri dishes with one of the following concentrations of NaCl (salt.):
0.200 M
0.100 M
0.075 M
0.050 M
0.025 M
0.000 M - Control
c) Add 2 ml of the salt solution indicated by the petri dish’s label, to the filter paper in the petri dish, using a pipette. Be sure to rinse the pipette carefully. Hint: You will be able to reduce the chances of error due to contamination if you apply the solutions to those petri dishes assigned the lowest concentrations, followed by those with successively higher concentrations.
d) Add 10 lettuce seeds to each dish. Space the seeds evenly on the filter paper so that they do not touch each other or the sides of the dish.
e) Place the dishes in a plastic bag, and seal it to retain moisture. Incubate in the dark at constant temperature (preferably 24.5 degrees C) for 5 days (120 hours). Record the time and date that you are starting this incubation period:
Starting Date_______________ Starting Time ___________.
f) Prepare for data collection by designing data tables that will illustrate the following:
i.) Table 1: The number of seeds that germinated when different concentrations of salt were present in the environment. Remember that you will need to record
the number of seeds that were placed in each Petri dish, the number that sprouted
and that you will calculate the percentage of seeds that germinate.
ii.) Table 2: The average root length of lettuce seedlings that germinated when different concentrations of salt were present in the environment.
g) Have your data tables checked. ____________ Data tables approved for use
Teacher Check
Data Collection:
h) Indicate the date and time that you are collecting data, next to each data table.
i) Record data in Table 1. Count the number of seeds that germinated in each petri dish, the number of total seeds that were present in each dish. Calculate the percentage of seeds that germinated.
# of seeds that germinated
% Germination=--------------------------------------------- x 100
Total # of seeds in the petri dish
j) Record data in Table 2. For each sprout, measure the radicle length to the nearest mm. (The radicle is the embryonic root). Look carefully at the plants to make sure you are measuring just the radicle, not the shoot as well. For example, in the picture below, you would measure just the part between the two arrows, not the shoot and cotyledons to the left.
k) Calculate the average root length for sprouts exposed to each salt concentration.
l) Compile data that each group in your laboratory section has collected using the classroom blackboard. Record this on the back of this sheet of paper.
m) Have your data tables from steps k and l, checked.
_________________ Data tables acceptable
Teacher Check
C. Bioassay Analysis
After you have collected data it is important to evaluate its quality, and to analyze what it tells us.
1. Consider the petri dish that was designated as the experiment’s control.
Control: Concentration=________ M NaCl
The control is used to identify how well the seeds will grow without any added contaminants. If fewer than 80% of the seeds in your control dishes sprouted, something may have gone wrong in your experiment. Describe the growth that you observed in the "Control" petri dish. If the germination rate is especially low, suggest factors that may account for this.
2. Consider the variability of results that were collected by different teams. Why might one "taskforce’s" results differ from another’s? Consult the Environmental Inquiry website (http://ei.education.cornell.edu/) for ideas regarding this important issue.
3. Use the computer to prepare a two graphs of the data that you collected. Figure 1 should illustrate the effect of salt concentration on germination rate of lettuce seeds. Figure 2, should illustrate the effect of salt concentration on the average root length of lettuce sprouts.
Have your graphs checked. _____________
Teacher Check
4. Describe any general trends in seed germination and growth that you observe.
5. Identify the pros and cons of using lettuce seeds to evaluate the toxicity of salt on plants.
Part II: To salt or not to salt???? Background Check!
At this juncture you have explored a technique that is useful to your taskforce, and have obtained preliminary information regarding how it might be used to assess the impact of road salt. It is valuable at this point to do a literature search to determine what is already known about the topic of interest. Otherwise, they may spend a great deal of time discovering that they have only "re-discovered" interesting information. You’ll use your knowledge of biology and your research skills to investigate what is known about the impact of road salt on living things and their environment. Later in the project to you’ll use this information to write the introduction to your scientific paper.
Three articles have been selected to assist you in your study of road salt and deicing alternatives:
*Cryotech CMA: Calcium Magnesium Acetate (http://www.ga.com/cryotech/CMA/htm)
*The New Hampshire Department of Environmental Services, Environmental Fact Sheet, entitled: Road Salt and Water Quality (http://www.state.nh.us.des.swqb-7.htm)
*The Adirondack Aquatic Institute’s Home Page
(http://www.paulsmiths.edu/aai/salt.html)
1. Identify the potential bias (if any) that the article is written from and suggest what type of information that the article might emphasize as a result:
CMA:__________________________________________________________
__________________________________________________________
__________________________________________________________
Road Salt and Water Quality:_______________________________________
__________________________________________________________
__________________________________________________________
The Adirondack Aquatic Institute’s Home Page: ________________________
__________________________________________________________
__________________________________________________________
2. Using the information from each of the articles, insert descriptive statements of the pros and cons of road salt as well as the pros and cons of the alternative compound, CMA, in the charts below:
Road Salt Use CMA Use
Advantages Disadvantages Advantages Disadvantages
Part III. Salt and Survival
Use your knowledge of biology and your critical thinking skills to:
1. Prepare a wet mount slide of a typical plant cell by adding one drop of water to the plant cell sample. Draw a diagram of this cell. Then draw a second diagram that illustrates what that same cell would look like if it had been placed in a 2% salt solution.
2. Describe how the salt concentration changed and how this influenced the water balance in the cell. Be sure to use the terms, "diffusion" and "osmosis", in your answer.
3. Prepare a brainstormed list of life processes that a plant uses water for. (For example, water is a raw material for photosynthesis.)
4. Based on these reflections, predict the impact that salt would have on a plant. Suggest characteristics that might enable certain plants to be more resistant to salt damage.
Part IV. Research: Project Design and Implementation
The principal investigator has challenged you to devise a unique study that will test a hypothesis designed to learn something new regarding the impact of road salt or its alternatives on plants and animals. Your team must opt to do an experiment that fits in one of the following categories:
A) It investigates the environmental impacts of road salt on plants further by
1) Measuring and testing actual road salt residue OR
2) Evaluating which plants are most and least tolerant to road salt damage
B) It compares the toxicity of road salt with that of CMA
C) It evaluates the usefulness of Daphnia or duckweed as a bioassay organism for
studying the impact of road salt on living things.
The Environmental Inquiry website (http://ei.education.cornell.edu/) will provide you with critical information as you develop ideas regarding experimental design. Be certain that you consult the "Design Challenge" and "Some Tips for Planning an Experiment" segments of the website for ideas. Consult the grading rubric/rating sheet to determine what is required in each segment of the journal article that you prepare.
1. Have the topic for your unique study checked by your instructor:
_______________
Teacher Check
2. State a hypothesis based on your knowledge of this topic:
3. Develop a diagram that illustrates the experimental procedure that your team is planning to use to test this hypothesis. Have this checked when it is complete.
_______________
Teacher Check
4. Specify the experimental protocol that you will use, carry out the experiment, analyze the results, and draw appropriate conclusions. Use the scientific journal article rubric to assess your product and that of your fellow taskforce members.
Part V. Let the Research speak!
Share your research results with a public official or employee who makes policy decisions regarding the de-icing of North Country highways.
Prepare a cover letter to accompany your scientific journal article that identifies your concern regarding this issue, offers a synopsis of your research findings, and presents your suggestions to a policy maker on how this issue might best be addressed in our region. Make suggestions that you identify as the best management practice for Lewis County given economic and environmental considerations.
Submit this letter with a copy of your scientific journal article for the final assessment of your product.