It’s winter in Canada, and for most of us, that means taking extra precaution to stay safe: bundling up in winter clothes, warding off frostbite, swapping to winter tires and dumping a ton of salt outside! In fact, the Government of Canada reports that about five million tonnes of road salts are used across the country every year. At the provincial level, Ontario uses 2 million tonnes of road salt as an anti-icing method for winter road maintenance. For the city of Toronto, up to 150,000 tonnes of salt are laid down across the city, this equates to over five thousand kilometers of roads. That’s a lot of salt!
Salt is used to melt the snow and ice so driving, walking and getting around the city in general is safer. It is popular with municipalities and contractors because it is cheap and can easily be distributed. However, there are several drawbacks to road salt. One drawback is that it is not always effective at very low temperatures. Salt is used to lower the freezing point of water to make it harder for ice to form, but this only works when temperatures are above -7 to -10 degree Celsius. When the temperatures fall below this, brine needs to be applied instead. Brine is a salt and water mixture that is laid down ahead of the snowfall to inhibit the ability of snow and water to freeze on roads. Another drawback is the damage and corrosion to roads, bridges, cars, as well as the economic costs of implementing corrosion protection measures.
In addition to this, road salts are also damaging for the environment, and we will expand more on that in the next section.
Environmental impacts of road salts
The environmental impact of winter salt use in Canada has been documented in several studies, including a comprehensive five-year scientific assessment completed in 2001 by Environment Canada. This assessment concluded that salt is entering the environment in quantities that may pose immediate or long term environmental risks. Elevated concentrations of chloride salts may cause adverse effects to drinking water, vegetation, aquatic life, and soil structure. The chloride from the road salts infiltrates waterways and simply accumulates in our water sources. Chloride also infiltrate soils which are then taken up by plants.
According to WWF-Canada, a big threat to wildlife and the health of creeks, rivers and lakes in Toronto is chloride contamination from excessive road salt application. WWF-Canada identified that chloride is accumulating at a staggering rate in flowing waters, groundwater and in stormwater ponds linked to the Great Lakes. Chloride levels in urban creeks and rivers in the winter are far above what is healthy for freshwater wildlife. When the water is too salty, species like fish, turtles and frogs can’t reproduce or survive. Some waterways in Southern Ontario now have eight times the recommended level of salt, surpassing more than 1,000 mg/L of chloride according to a WWF report.
Health Canada estimates that 5% of aquatic species would be affected at chloride concentrations around 210 mg/L, and 10% of species would be affected at chloride concentrations around 240 mg/L. Health Canada points to water samples taken from four Toronto-area creeks that had chloride concentrations from 1,390-4,310 mg/l. Levels this high greatly affect the proper distribution of oxygen and nutrients in water bodies, and make the bottom layers of water to have less oxygen. Less oxygen means the osmoregulation or water to oxygen balance in aquatic species is affected which can inhibit the growth, reproduction and food sources of aquatic species.
Given these environmental impacts of winter salts, it is vital to find eco friendly, yet effective alternatives to road salt. Some of these include:
- Sugar Beet Juice
Sugar beet juice offers a highly concentrated, high performance deicing agent that is biodegradable and can be applied directly to ice for the least impact on the environment. It can also be incorporated into traditional road salt to increase its effectiveness and, ultimately reduce the amount of damaging materials on your driveway.
2. Grape Skin Compounds
One study found that a solution made with grape extracts melts ice quicker than conventional salts, all without damaging roads or harming the watershed. Researchers at Washington State University used chemical degradation and fermentation to extract chemicals from wasted grape skins. The resulting solution melted ice quickly, and the process to make it also produces no waste.
3. Coffee Grounds
Coffee grounds are somewhat effective in melting ice, plus they add traction to the walkways. Nitrogen in the coffee grounds reacts with the ice to help melt it. However, it’s important to be cautious about how much nitrogen you add, which can run off into local aquatic ecosystems and cause eutrophication.
Sand is the most relevant of road salt alternatives and is also the most cost-effective. The impact sand has on surrounding waterways and plants is extremely minimal. However, sand is meant to be kept on the surface as it acts as a means of traction rather than a melting agent.
5. Alfalfa Meal
Alfalfa meal is typically used as a fertilizer, it’s also effective for melting ice. Alfalfa meal has a grainy texture that also offers more traction as you walk, and you can typically find this product at garden supply or home improvement stores.
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