Snow Cone Sidewalks: The Environmental Impact of Deicing

By Claire Mathieson

As someone who has never experienced a New York winter (or, as I’m sure some would accuse given my Californian background, any winter at all), I was expecting to see a city overrun with all manner of bland colors come my return from winter break: the dull brown of former greenery, bright freshly fallen white, the dismal grey of snow that has been belched on by cars and trampled by feet. What I failed to envision were the toxic turquoises and poisonous purples scattering the sidewalks like so much shattered rock candy.

Sodium chloride – common table salt – lowers the freezing point of water and is therefore a common deicer on roads and sidewalks alike. While salt sounds mild next to the myriad other toxins introduced into our environment each year, its excessive application is cause for too-much-of-a-good-thing concern. The National Research Council has determined road salt use in the United States to fall somewhere between 8 and 12 million tons per year, with New York among the top three using states at 500,000 tons per year. Deicing in such a manner has led to water pollution, as well as harm to vegetation, trees, and soil. Salt accumulates in soil, keeping plants from absorbing water and nutrients and preventing new plants from growing. Large concentrations of sodium can cause soil to harden, making it difficult for water to infiltrate the surface. Furthermore, many deicers caution users about their effects on concrete. The freeze-thaw cycle, through which water permeates concrete, freezes, and expands, damages concrete naturally, but application of deicers results in more frequent occurrences of this phenomenon and increased stress on the surfaces they are applied to. While salt is the main ingredient in most deicers, it is often laced with other additives, all of which carry their own effects.

As far as the strange coloring goes, I found that, at least in certain cases, it is meant to be an “EnviroIndicator” – to allow the user to be better able to see where they have already applied it and to prevent them from adding too much at a time. The one product I found that made a mention of it, “Pure & Natural Deicer,” claims the color is due to a small amount of biodegradable, organic dye. While it is unclear whether other products include color in order to cap application and what comprises their dyes, it is possible that the garish shade is more helpful than threatening in the long run.

I had no trouble determining which product Barnard College uses to knock “slipping” off the list of excuses its students can use for lateness; our Elliot Hall entryway, normally home to little more than a newspaper rack, now holds a wheelbarrow, a shovel, and a hefty bag of “Keep It Green Snow and Ice Melter.” According to Dart Seasonal Products, Inc. “Keep It Green” uses a mix of calcium magnesium acetate (CMA) and potassium acetate to deice. Fortunately, CMA is considered to be the most environmentally friendly deicer, while potassium acetate is biodegradable. “Keep It Green” also boasts added fertilizer, meant to aid plants that would normally wither under the influence of deicers. However, it is important to consider the fact that fertilizers, though beneficial to plants in reasonable amounts, can run-off into water supplies and cause eutrophication – algal blooms due to excessive nutrient concentrations. The algae die and decompose, depleting the water around them of dissolved oxygen and leading to fish and animal death. While “Keep It Green” sounds like it is a relatively smart choice, we must not distribute it thoughtlessly, always keeping in mind its potential to affect our environment.

While I was unprepared in terms of footwear for what New York weather had in store for me and appreciate not slipping when I step out into the cold each morning, I do think it is important to, well, take everything around us with a grain of salt – to consider every possible ramification of what we do to our environment and to search for alternatives wherever our actions are tagged with costs.

Claire is a sophomore at Barnard College and Features editor for The Nine Ways of Knowing.

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