Know Your Winter Weather Deicing Agents
By Andrea Berry, Michigan Water Stewardship Program
As the winter months approach and the snow starts to fall we all look for ways to
stop the slide of slippery sidewalks. On many roads and walkways gravel, sands and
deicing salts are spread over slick spots to add traction and melt snow and ice. Gravel
and sand are applied to surfaces to increase traction, but at a cost to water and air quality.
Deicing salts are useful because they both melt snow and ice and add traction to slippery
surfaces. Unfortunately, salts used to deice surfaces eventually runoff with melted snow
and have an unfavorable impact on water and soils. New alternatives to salts and gravels
are available that avoid harmful environmental influences of traditional deicing methods.
Knowing how deicers work and what happens to them once they reach the environment
will help you to make an informed decision about which type of deicing agent will work
best on your walkways.
There are three categories of commercial deicers used today including sands
chloride-based deicers, and acetate-based deicers. Sands and gravels have been used
since the early 20th century to add traction to slippery surfaces. Although they do not
melt snow, sands and gravels do have damaging impacts on the environment and human
health. When gravel and sand is used to add traction to surfaces it stays with that snow
and ice and eventually is carried to storm drains and surface waters when the snow melts.
The result is an increase in suspended sediment and turbidity in water systems reducing
the amount of sunlight than can enter a stream. Without adequate sunlight plants cannot
photosynthesize and the amount of free oxygen in the water is reduced. Small sand
particles also get caught in fish gills and suffocate them, and settled sands can smother
bottom-feeding organisms. Sands and gravels also have adverse influences on air quality
by releasing small particles into the atmosphere. Sand is listed as a carcinogen and can
potentially cause serious lung disease when ingested in large amounts or over a long
period of time.
Chloride-based deicers are efficient in loosening snow and ice making manual
removal much easier. Sodium chloride, or table salt, is the most commonly known
deicing salt and has been used for years because of its effectiveness, abundance, and low
costs. Other chloride-based salts commonly used include potassium chloride, calcium
chloride and magnesium chloride. All work essentially the same way by melting down
through hard surfaces and loosen snow and ice by lowering the freezing point of water.
Environmental and health concerns surround the use of salts for deicing. Chloride-based
deicers increase the salinity of soils, surface and groundwater. People who drink water
high in chloride are more susceptible to hypertension. Roadside vegetation is also at risk
of damage by salt deicers. An increase of salts in the soil makes it difficult for plants to
absorb water and nutrients and cause death of vegetation. Wildlife is also attracted to the
taste of salt on the roads leading to a greater chance of a roadside collision with an
animal. Salts also have a corrosive effect on cements and metals and can cause damage
to bridges, vehicles, and other utilities. Most commercially sold deicing salts contain
inhibitors that reduce corrosion of metals, but cement is still at risk to cracking and
scaling.
An alternative to sands, gravels, and salt-based deicers is Calcium Magnesium
Acetate (CMA). Developed in the 1970s by Chevron, CMA works by preventing snow
and ice particles from adhering to one another and to road surfaces. Snow that
accumulates after a CMA treatment is lighter and drier and does not adhere to pavement
so snow removal is much easier and slippery surfaces are averted. CMA is made from
limestone and acetic acid, the primary ingredient in vinegar, and is being used in
environmentally sensitive areas because it is biodegradable and low in toxicity having
little impact on vegetation, animals, and water. Because CMA is organic it can cause
depletion of oxygen in soil and water when accumulated in high concentrations. CMA is
commercially available at a higher cost than chlorine-based deicers and sands.
Slippery roads and walkways are a hazard and must be treated to prevent
dangerous conditions for people, property and the environment. Sand and gravel do not
melt snow but effectively increase traction of roads and walkways at high environmental
and health risks. Commercial chloride-based deicers melt snow and ice and add traction
to roads but put wildlife and vegetation at an environment risk. Chloride-based deicers
can enter ground and surface waters and increase the salinity of the water people drink,
which can be harmful to human health. Roads salted with chloride-based deicers also
attract wildlife increasing the occurrence of a collision with an animal. A new alternative
to salt-based deicers that works effectively to melt snow and ice and add traction to
slippery surfaces, while having little environmental and health risks is Calcium
Magnesium Acetate (CMA). This new salt-free deicer is organic and highly
biodegradable and readily available, however at a higher cost than traditional deicing
methods. Whatever you choose to remove the slick from your sidewalks, read the label,
store it properly, and know what might result from an application. What you do in and
around your home has an impact on the world around you.