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Where Have All the Road Salts Gone, Long Time Migrating

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Author Contact Information

Peter M. Amati, Jr.
Holliston High School
Holliston, Ma. 01746
School Phone 508-429-0677
amati@tea.rice.edu

Overview
In this activity students will investigate the migration of road salt (from road's edge into a distance of six meters) following its application during a snow storm and the subsequent plowing of the roads.

  • discuss the idea of a specific protocol to be followed by all students in collecting data.
  • point out the significance of a standard "controlled" protocol for all parcticipants.
  • demonstrate the proper use of the equipment used in this lab.
  • gather data from the field.
  • learn how to properly use conductivity meter.
  • test all samples for various concentrations of salt.
  • learn to use Microsoft Access as an example of a database.
  • enter all data into a database.
  • tabulate and graph all data sets.
  • analyze data sets acquired throughout the winter season.

Grade Level/Discipline
Grades 9-12, Physical science and general science classes, but may be adapted to middle school

National Standards
Science as Inquiry standard A , Physical Science Standard B, Science and Technology Content standard E, Science in Personal and Social Perspectives Content standard E

1.Benchmarks 12C,

State Standard: Massachusetts' frameworks

1. Strand 1 Inquiry #'s 1 -34
2. Strand 2 Domains of Science
3. Physical Science #'s 3, 64, 69
4. Life Science #'s 46, 47,
5. Earth and Space Science #'s 46, ,63, 65
6. Strand 3 Technology #'s 2, 6, 10, 15, 16, 18, 19, 27, 32, 37, 38, 40, 53, 54, 56, 60, 61, 62, 63, 78,
7. Strand 4 Science Technology and Human Affairs #'s 2, 3, 10, 11, 15, 16

Pre-activity set-up

Materials

  • seven "Deli Containers" (1 pound size with lids). Number two sides of cup with indelible marker, so that individual cups can be identified.
  • conductivity meter
  • four inch (approx.) piece of standard 2 inch PVC pipe (available at Home Depot and other hardware stores)
  • piece of twine 6 meters long and marked of in meter increments
  • two metal plate 4" X 4" X 0.13" (electric box covers work well)
  • Omega conductivity meter (Texas Instrument CBL with conductivity probe works well) print out lab format and data sheets to be used

Time Frame
One class period (approximately 55 minutes) to introduce project and demonstrate equipment and processes. Time before and after school to collect samples, test samples and to enter data into database.(time varies with number on snow storms during the winter). One class period (approximately 55 minutes) to analyze data and pool data

Engagement and Exploration (Student Inquiry Activity)
A protocol that works: At some point after the concepts of solubility, concentration and conductivity have been covered (but before the first snowstorm), introduce the following project.

Start with a discussion of the fact that because we live in a climate where we have snow and ice we, as a society, are compelled to come up with ways to make our roadways safe.

Raise the question,. What are some of the ways we remove snow and ice from our roadways? (Plowing sanding and salting.) Have the kids describe how and why these methods work.

During this discussion raise the question,. What do the highways signs saying "WARNING!! Watershed area, minimal road salt used" mean and what is the significance of these signs? (Many kids have noticed the movement of road salt into the environment as the obvious browning of grass, shrubs and trees along roads edge or arcticles from the local papers about the pollution of wells/ground waters by road salt.) Pursue the idea that the road salts, if they migrated, might end (in fact do) end up polluting various, ponds, puddles, pools and wells.

Question how we could measure movement of road salts? (Responses vary from spectrophotometry or measuring the conductivity of the snow on the side of the road to tasting the snow for salts at different distances from the road's edge.

At this point I describe one part of my work in Antarctica, measuring the migration of salt in cores of ice taken from sea ice. (Because the sea water freezes from above [water -2C air -30C] the freezing point depression causes the water on the top to freeze first. This forces the salt out of the upper layer and makes the layer below saltier. As the freezing continues the salt continues to migrate out of that layer into yet deeper layer of the ice making the lower layers of ice still saltier.) The purpose of this research was to document the type of ice (fresh/ various concentrations of salt) that was found in that parcticular area that had been photographed by satellites. (Ground truthing). Ask students to read about Peter Amati's research in the Weddell Sea on the Teachers Experiencing the Antarctic and Arctic web site ../../tea_amatifrontpage.html#calendar

On the day of the snow storm or the day after (must allow time for road to be sanded and salted and plowed) the student will employ the protocol set out in Student Reproducible Masters.

Explanation (Discussing)
Have another group of students using the computer take data from data base and graph it plotting Conductivity as a function of Distance from Road's Edge. (A typical graph looks like Figure #3)

The graph indicates that the conductivity (salt concentration) decreases with distance from the road's edge. The second peak was totally unexpected, but shows up on almost all data sets suggesting strongly that it is not an aberration. Data analysis suggests (remember this is real research, there is no definitive answer) that this peak, high concentration of salt, is probably due to the speed of the plow and the temperature which both influence how far a splash of road's edge snow is forced deeper within our field of measurement. Great challenge for kids (isn't this what its all about) and a great opportunity for extension of research/project.

Elaboration (Polar Applications)
While in Antarctica one of my jobs was measuring the migration of salt in cores of ice taken from sea ice. (Because the sea water freezes from above [water -2oC air -30oC] the freezing point depression causes the water on the top to freeze first. This forces the salt out of the upper layer and makes the layer below saltier. As the freezing continues the salt continues to migrate out of that layer into yet deeper layer of the ice making the lower layers of ice still saltier.) The purpose of this research was to document the type of ice (fresh/ various concentrations of salt) that was found in that parcticular area that had been photographed by satellites. (Ground truthing). The use of satellites is critical and the only "relatively" easy and "relatively" inexpensive way to study the vast amount of sea ice (some 5.8 million square miles) that forms annually during the austral winter This sea ice is most influential on the conditions in Antarctica in parcticular, which in turn plays a most direct and definitive effect on the earth's climate.


Satellite Image of Sea Ice in Weddell Sea (taken from http://southport.jpl.nasa.gov/polar/sarimages.html)

Ask students to read about Peter Amati's research in the Weddell Sea on the Teachers Experiencing Antarctica and the Arctic web site ../../tea_amatifrontpage.html

Another interesting reference can be found on the GLACIER web site at ../../expedition/2_trainingcamp.html Both sites will give insite into the research that goes on in Antarctica.

Have the students go to the following website http://www.ce.vt.edu/enviro2/gwprimer/roadsalt/roadsalt.html This site will allow the students to see a real life application to their real life research.

Have the student go to the following website http://southport.jpl.nasa.gov/polar/index.html This web site will provide an explanation of statilite imagery

Exchange (Students Draw Conclusions)
Students will compare individual graphs of Conductivity as a function of Distance from Road's Edge. Have computer team print out graphs for each kid's different snow storms so that they can see if the slope of the curve s are consistent.

Evaluation (Assessing Student Performance)
Rubric dealing with formal lab report and graphed data sets.

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