THE CONSEQUENCES OF ROAD SALT ON WATERWAYS

During the winter and fall seasons, salt is applied to the sidewalks and roads each year to help melt the snow. In Ontario, approximately 3-5 million metric tonnes of road salt is used annually to maintain roads. Salt lowers the freezing temperature of the water, hence melting the accumulation of snow and ice. However, the salt doesn’t disappear with the snow but washes into creeks, lakes, rivers and other water bodies. Chloride is unable to be filtered out through soils, plants, or removed by wastewater treatment processes.


The City of Toronto has found that chloride is accumulating at a rapid rate, affecting our flowing waters, groundwater, and stormwater ponds linked to the Great Lakes. Chloride levels in urban water and rivers are much higher than what is healthy for freshwater wildlife. Levels of chloride higher than 250 ppm make it inhabitable for most aquatic animals. The chlorine levels in the water ruin the ability of the aquatic organisms to regulate how fluid passes in and out of their bodies. Subsequently, when the salinity in water is over the threshold, the animals have to uptake salts from water. This results in the destruction of their body tissue, ultimately leading to death.


Furthermore, the accumulation of road salt in the lakes and rivers results in bodies of water having a higher ppm solution. Increased salt in our drinking water can result in dehydration. Human kidneys can only excrete small amounts of salt from the body at a time through urine. To remove huge amounts of salt, the kidneys need to produce a lot of urine to flush the sodium out. Essentially, when you drink water high in chloride, your body will require even more water to dilute the saltwater and eliminate the sodium in your body. If you are not drinking enough freshwater, you will get more dehydrated from urinating too much. If there is a high amount of sodium in your blood, circulation increases. This attracts more fluid which increases the pressure in your blood vessels thus, resulting in dehydration. Your body is trying to flush out as much sodium as possible which means, the vital organs suffer. Similar to aquatic animals, this can lead to organ failure. If not managed properly, high levels of chloride in our water bodies could result in serious public health issues - for both, aquatic species and humans.


Tips and tricks to help lower the use of road salt (from the City Of Toronto)


  • Always shovel first, road salt DOES NOT help on the top pile of the snow, so any use of salt will only go to waste. Salt should be used after shoveling the snow first.

  • Be sure to use the right amount, not too much. Follow the manufacturer’s instructions on how much product to use and check its effective temperature range. Salt loses its efficacy at -10C and is inefficient below -20C.

  • Use sand to help with traction (if needed).

  • Do not apply salt somewhere if you don’t walk there. If all you need is a narrow strip, then only salt that much of the area. This can save a lot of salt as you are not unnecessarily using salt.

References:

  1. https://slate.com/technology/2010/02/does-road-salt-harm-the-environment.html

  2. https://www.toronto.ca/services-payments/water-environment/live-green-toronto/reducing-the-use-of-road-salt/#:~:text=Salt%20is%20damaging%20to%20shoes,or%20even%20contaminate%20drinking%20water

  3. https://www.researchgate.net/post/Does_salt_have_any_impact_on_the_aquatic_life

  4. https://sciencing.com/salt-affects-living-organisms-6581850.html

  5. https://www.watersystemscouncil.org/download/wellcare_information_sheets/potential_groundwater_contaminant_information_sheets/4197657Sodium_Update_September_2007.pdf








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