Road salt in winter has year-round consequences


Every fall, Canadians patiently wait for the trees to turn and the leaves to crunch. In winter we hear another crunch – the crunch of road salt.

Road salt is used to remove ice from surfaces such as streets, sidewalks, and parking lots. When people talk about road salt, they often worry about what salt could do to their vehicles, dog paws, or winter boots.

There are also some environmental concerns as de-icing salt eventually ends up in our soils, local lakes and rivers. Salty water flows into our soils and local bodies of water through surface runoff and stormwater pipes, and eventually ends up in the groundwater. This promotes the long-term storage of salt in the environment and has further effects on freshwater life, government infrastructure and drinking water.

These concerns are usually raised in winter when we actively see salt cars and mountains of salt on our drives or walks to work and school. While some of our worries fade when the warm spring weather comes my research shows the effects of extensive road salting on the environment in the past year.

No longer a pure winter theme

My research with Donald Jackson at the University of Toronto showed that increased levels of chloride can now be found year-round in freshwater systems in the greater Toronto area, which are strongly correlated with road salt. The effects of road salt are not generally investigated in summer. However, it is important to understand how this can affect the environment during the “off season” of salt in order to understand the gravity of the situation.

Our study found that during summer time, which is also the off-season for chloride, chloride levels exceeded established levels Canadian Federal Guidelines for the Protection of Aquatic Life.

At some of the monitored locations, we found that over 50 percent of the aquatic biological communities may be considered stressed by chloride based on these guidelines, which are based on toxicity tests for aquatic organisms.

This means that summer time is now a time of likely chloride stress, higher water temperatures, and earlier life stages of aquatic organisms (such as eggs and larvae) that may be more sensitive to stress. When these factors combine, water species are at increased risk.

Why should we worry?

Road salt poses a risk to freshwater species that rely on low salinity. Freshwater species have specific biological adaptations to low salinity, in contrast to their marine counterparts, which have different types of adaptations.

Studies show that increased chloride concentrations in connection with salt, can lead to disturbances in food webs, as sensitive species are stressed at high concentrations. For an aquatic organism, salt stress can cause energy to be diverted to maintain basic functions, meaning that less energy is used for growth and reproduction.

It has been found that high salt concentrations too Decrease in egg mass for aquatic organisms, and Decrease in growth rate. Essentially, this means that sensitive species can eventually be “filtered out” of food webs, leading to a decline in biodiversity.

Road salt leads to high chloride and sodium concentrations in local waters. Increased chloride content in the drinking water supply can lead to faster corrosion of the drinking water infrastructure, e.g. private and municipal wells and pipes. this reduces security of drinking water. An increase in sodium levels is also of concern for people with high blood pressure.

To top it off, salting can lead to faster rates Corrosion of bridges and roadswhich also endangers the road infrastructure.

Missing: efforts to reduce road salt

Were de-icing salts first used in North America in the 1940s, and as its use increased exponentially with urbanization and road construction, sodium chloride became the most popular. With an increasing understanding of the risks to the environment and human health over time, efforts to reduce the use of road salt include the use of alternatives such as: Beet juice.

However, these alternatives can be expensive and have their own pitfalls, such as adding more nutrients to aquatic systems. Understanding how much salt to apply and when is a critical part of salt and ice management. In addition, shifts in the ice safety perspective can be made. For example, some regions require winter tires for vehicles while people use chains, boot spikes, and other personal traction devices.

With one recently Salt peaks, delivered by the Lake George Association in New York, a speaker appropriately described our current relationship with salt as “Over-salting comes from a place of love, worry, and lack of security” because icy conditions are considered unsafe.

However, short-term prospects of ice security blind us to the love, concern, and desire for long-term security of our drinking water supplies and environmental integrity.

Curbing our winter road salt addiction

We need to first identify the year-round effects of our winter choices and then take action to reduce the effects. We can share the effects of road salt and the individual actions we can take, such as understanding how much salt needs to be deposited on our private property, adjusting our expectations for winter roads, and using winter tires and boot spikes to provide an extra layer of security.

On a larger scale, mandatory salt application certifications can provide training for snow removal companies and, if properly designed, provide significant incentives. For example New Hampshire Green SnowPro certification provides a limited liability exemption for snow removal companies if they are certified.

This will protect snow management companies and recognize their training programs as safe. Other organizations like the Smart About Salt Council, offer the opportunity for certification, training and general knowledge about salting.

To fully understand the effects of salts, the snow removal industry and scientific researchers need to be brought together, as understanding where and how much salt is used is an important part of environmental modeling. This association can be casual, such as through Job interviews.

It can also be more formal, for example through joint research or educational initiatives such as Partner in Project Green Resource Industry development to understand the effects of road salt and resources to learn more.

Road salt pollution is an issue that can be addressed immediately, rather than relying on technological advancement, as action can be taken at the individual, federal, and all levels in between. These measures should be taken quickly to ensure a less salty future for our freshwater streams, lakes and our drinking water.

So if you hear the crunch of your boots on road salt this winter season, you know that the salts we use now may not be visible after winter, but the effects on the environment and our drinking water are year-round.

Lauren Lawson, PhD student, Institute for Ecology and Evolutionary Biology, University of Toronto

This article was republished by The conversation under a Creative Commons license. read this original article.


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