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Where Have All the Road Salts Gone, Long Time Migrating

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  • 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

Fill out "Salt Migration Data Form" completely and accurately (See form in Student Reproducible Master section) . Go to the site you have decided to take samples from. Using the 6 meter length of twine, marked off in 1 meter lengths, and run out a straight from road's edge to side of road for a distance of six meters. (Laying the twine on top of the snow is adequate, there is no real reason to dig trench for twine to lie in, the distance will be close enough for the purpose of this exercise.) Using the metal plates cut a "snow pit" out of the surface of the snow at road's edge and then at each of the 1 meter marks on the twine. See Figures #1 and 2

These "snow pits" are made by inserting one of the metal plates vertically into the snow and then forcing the other plate in at a right angle creating a shelf in the snow . The 2" diameter pipe is then forced into the top of the vertical wall of the snow pit until it is full of snow. This pipe ("cylinder full of snow") is cut off at he inserted end of the pipe so that a full pipe of snow is attained. This snow sample is then placed in a designated 1lb deli cup; its number recorded and the cover placed on. Samples are then collected at each of the remaining 1 meter sites and returned to school.

Upon returning samples to school conductivity is measured using conductivity meterand data recorded (Have list of all numbered cups available. Have kids remove cover, measure conductivity, place probe in distilled water to keep probe properly calibrated, record conductivity reading and do next cup in series. (NB when my classes do this lab there are as many as 500 individual cups to have data taken from, so I set up sort of an assembly line with people opening cups, measuring conductivity, monitoring the calibrations on the conductivity meter; recording data, washing the cups and covers and drying for redistribution for the next possible snow storm.)

Another group of students will enter the "Salt Migration Data Form" into the data base.

Salt Migration Data Form

Please fill out one of the forms for each and every snowstorm and return it to class, along with seven snow samples on the next scheduled school day.

Site #

Date of Sample


Street and number


Location where sample was taken (e.g 2" to left of mail box)

Weather (circle one) clear, partly cloudy, cloudy, snow, rain

Wind (circle one) calm, gentle, strong

Cup# at 0 meter
Cup# at 1 meter
Cup# at 2 meter
Cup# at 3 meter
Cup# at 4 meter
Cup# at 5 meter
Cup# at 6 meter
Cup# at 7 meter

Discussions Questions/Extensions ......

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