Researched by Taylor S.
2003-04

• PURPOSE 
• HYPOTHESIS 
• EXPERIMENT DESIGN 
• MATERIALS 
• PROCEDURES 
• RESULTS 
• CONCLUSION 

• RESEARCH REPORT 
• BIBLIOGRAPHY 
• ACKNOWLEDGEMENTS 

• ABOUT THE AUTHOR 

Introduction

Every year people put deicer or rock salt on their driveways, sidewalks, and their roads. Every spring the snow melts off and mixes with the deicer or rock salt to make a solution containing the deicer from the winter before.   That very solution will find its way to lakes ponds and streams. The problem with that is deicer is like a poison and kills some of the organisms that live in those lakes and streams. Daphnia are a source of food for many of the smaller fish and if the daphnia die the fish would not have anything to eat which would hurt the food chain severely.

Daphnia

Another name for daphnia is “Water Flea” they call it the water flea because of their short jerky hopping movement through the water.   Many fish depend on daphnia to survive, this is because the small fish eat microorganisms. Daphnia live in fresh water like ponds, lakes, and streams. They grow up in just a few days. Using a microscope you can count their heart beat or tell if they’ve been eating. They only live about 40-56 days.  

There is a very big difference in size depending on the species of daphnia. Daphnia are about 1/125 to 3/4 (. 2 to 18 millimeters) of an inch.   They move in the water by rowing themselves along. They use their antennae, which are located on the head to feel around. Daphnia have a clear outer shell called a carapace. The carapace is clear so it is easy to measure the heartbeat or even observe what they’ve been eating. The carapace does not cover the head of the Daphnia. They have six pairs of legs, which they use to take particles of food from the water.  

Culturing Daphnia

A 3-L vessel containing 30 daphnia will produce about 300 young per week. If the container is larger the daphnia will grow larger.   Containers that are about 10-100 gallons (38-380L) are the best kind of environment for an experiment.

Good conditions for the daphnia are 
•PH 7-8. 6 
•Less than 30 daphnia per 3L container 
•Water temperature should be about 20-25*C 
•Dissolved oxygen 6mg/L or higher
•Water hardness 160-180 mg CaCO3/L 
•A cycle of 16 hours of light and 8 hours of dark per day.

Salt

People started using salt on the roads in the 1930’s. In the 1960’s salt and plowing were done together. Salt is a main deicer because it’s most available and most cost effective safe deicer. There are several types of salt but the main type of salt is rock salt. Rock salt must be mined from the earth but the other kind used is solar salt, which evaporates from seawater.   About 15 million tons of salt are used in the US yearly and 4-5 million tons in Canada.   Salt may be used on its own if there is ice or not enough snow to plow.   Almost all snowplows now use salt too. We use salt to keep snow and ice from sticking to the pavement. Research shows that salt makes accidents happen less often. When you put salt on ice or snow it makes brine that has a lower freezing temperature than the surrounding ice or snow (the normal freezing point is 32*F. The melting point is when the vapor pressure of the solid and the liquid are alike and the pressure totals one atmosphere). We still use salt today because it is: 

• Readily available 
• The least expensive deicer
• Easy to store and handle
• Easy to spread 
• Non-toxic to humans
• Harmless to skin and clothing
• Relatively harmless to environment when it is used and stored properly

Other Alternatives for Salt

Most other deicers that are as effective as salt are very expensive.   Some may have a very dangerous effect on the environment, or pavement.   The National Conference of State Legislators said, “Several alternatives to deicing salts have been investigated or tried, but they tent to be too expensive, damaging to highway structures, more toxic than deicing salts or not as effective. The alternatives include other deicing chemicals, pavement heating systems, mobile thermal deicing systems, and mechanical equipment. ” We are still trying today to find something as effective, safe, and inexpensive as salt. Regular salt is more effective and economical, when used right and sagely. Salt is the best way to protect the roads from ice or snow.  

Deicers

Many people don’t use deicers correctly. They put the deicer down then wait until the snow or ice melts. This isn’t the right way because it is very expensive and uses too much deicer. The right way to do it would be to put the deicer down just to loosen the ice then use a shovel to scrape off the ice or wait for the snowplow to do it. If you do this it will save deicer and makes the damage to concrete or vegetation less likely.   The two main things used to melt ice are calcium chloride and sodium chloride  (rock salt). They use special additives to stop the salt from caking.   The most frequently used addition is called sodium Ferro cyanide that is also called Yellow Prussiate of soda (YPS). Another is called ferric ferrocyconide, which is also called Prussian Blue. They are usually added in amounts of 20 to 100ppm. Ice melt also has something called heat liberation, as the deicer dissolves it gives off heat. This is called an exothermic reaction. A pound of calcium chloride gives out 290 BTU when it’s dissolving. There is an opposite effect for sodium chloride, for example it actually needs 39 BTU to turn into solution. Potassium chloride requires even more heat (170 BTU), and urea needs 106 BTU.  

Highway Safety

If there is an accident due to the snow plows not putting down deicer it is legal to sue them. The deicer makes the roads safer by melting off the ice which means that there is much less of a chance of cars sliding off the road or getting into wrecks.  
 

The illustration above came from the Salt Institute’s web page, “Deicing and 
Anti-icing for Safety and Mobility” at http://www. saltinstitute. org/30.html.   It shows the safety improvements of salting icy roads. Marquette University’s Department of Civil and Environmental Engineering found that salt reduced accidents by 88. 3%. At lower temperatures rock salt may be more effective. The tires normally would not produce enough friction to make the rock salt a solution if the temperatures are below 15*F and 20*F there normally wouldn’t be enough heat to turn the deicer into a solution.  

Summary

Deicers can be a help and they can also be a hindrance at the same time. They help the people driving on the roads in the winter but in turn they cause damage to the food chain because the deicer kills the microorganism that fish feed on.
 

Clare, John. “Daphnia: An Aquarist's Guide” http://www. caudata. org/daphnia/Cornell University and Penn Sate University 

“Culturing Daphnia, and Daphnia in Various Life Stages” Environmental Inquiry http://ei. cornell. edu/toxicology/bioassays/daphnia

Kirchner, Henry. “Using Deicers Correctly” http://www. saltinstitute. org/kirchner-1.html

MacDonnell, Greg. “Deicers… and the degrees they’ll go to. ” Grounds Maintenance http://grounds-mag. com/ar/grounds_maintenance_deicersand_degrees_theyll/

McGuinnes, Keith. “How Does (too much) salt affect land plants” http://www. madsci. org/posts/archives/mar97/853362106

McLaughlin, P. A. “Water Flea. ” The World Book Encyclopedia.   1999.  

Salt Institute. “Highway deicing and anti-icing for safety and mobility” http://www. saltinstitute. org/30.html

Schuman, Kai. “Background, Size, Life cycle of Daphnia, Nutritional value, Physical Requirements, Your Culturing Tank, and Trouble Shooting. ” Background http://www. ee. pdx. edu/~davidr/discus/articles/daphnia. html

Van Egmond, Wim. “Water-flea anatomy”http://www. microscopy-uk. org. uk/mag/indexmag.html?http://www. microscopy-uk. org. uk/mag/artmar02/fleanatomy.html

Winter, Mark. “Melting Point” Webelements http://www. webelements. com/webelements/properties/text/definitions/melting-point.html