Research Challenge 2:
What are the environmental impacts of road de-icing?
Many towns in snowy parts of the country are trying to cut down on their use of road salt. Not only does the salt cause corrosion of vehicles, it also has environmental effects when the the snow melts and salty water runs off into streams, rivers, and lakes. One alternative to salt is sand, which does not melt highway ice but does help to increase traction. The disadvantage of sand is that unless it is cleaned up at the end of the season, it tends to clog drainage pipes, channels, and streams.

Another alternative is other chemical forms of salt. Normal road salt is sodium chloride (NaCl). Many homeowners buy de-icing products that claim to be less corrosive and more environmentally friendly than road salt. Usually these consist of either magnesium or calcium chloride (MgCl₂ or CaCl₂). Because of cost, these products generally are not feasible for widespread use on highways.

In recent years, a new product called Ice Ban Magic has been introduced and is being field tested by highway departments in some towns in upstate New York. A by-product of commercial brewing and food production, Ice Ban Magic is a biodegradable liquid similar to molasses. It can be spread directly on roads or mixed with sand or road salt.

Design and carry out an experiment to assess the environmental effects of road salt or a road salt substitute. You may use one of the following questions, or create your own:

• Is MgCl₂ or CaCl₂ less toxic to lettuce seeds than NaCl?
• By mixing Ice Ban Magic with NaCl, can you get the same or better melting power with less potential environmental impact?
• How much do you have to dilute Ice Ban Magic in order to observe no effect on lettuce seed germination or radicle length? What dilution inhibits growth by 50%?
• Using field tests along roads in your community, can you detect any changes in water quality due to highway de-icing?

Before you begin, we encourage you to call your local highway department and ask what methods are used for highway de-icing in your community -- perhaps you can design an experiment based on your own local roads program.

Reference Materials:
Chemical Composition of Ice Ban Magic

Research Challenge #1
Research Challenge #3