EducationEducation is a large part of what we do! If you have a group (adults or children) who would like to hear more on a conservation subject contact us to set up a date and time! The following page highlights a conservation or nature related topic we feel the need to share!
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Winter: Let the snow, ice, and salt begin!
It is that time of year again! Jack Frost as entered our area bringing his pals--Snowflakes and Ice--with him. That means we will be breaking out the sidewalk and road salt to avoid treacherous falls and slick driving conditions during these winter months. How exactly does salt perform this magic? What are the implications for using salt? Do we have alternative options?
Salt used for the roadways and sidewalks is most commonly the unrefined version of our table salt! Salt reduces the freezing point of water meaning it will take temperatures lower than 32 degrees Fahrenheit to make salt water freeze. Salt does need water to mix with so you might ask "How does putting it on ice make it melt?" Well, ice actually has a very small film of water on it allowing the salt to lower the freezing point and begin melting some of the ice creating more water to mix with and so on. However, this does take time so oftentimes road departments will try to pre-treat roads to avoid ice forming in the first place.
Now that we know the process behind the magic let's discuss the environmental implications salt has. When the salt washes off our roads and sidewalks it eventually makes its way to our streams or aquifer system. Runoff with high salt concentrations will be dense compared to freshwater and will sink to the bottom. This can cause oxygen depletion in the ecosystem as the saltwater layer will restrict gas exchange. A 2014 study also found that many urban streams had high levels of chloride, which is toxic to aquatic life. Chloride disrupts aquatic organisms growth and reproduction, food sources, and amphibians ability to maintain water and salt amounts in their bodies (osmoregulation). Unfortunately, ecosystems also don't have a biological process to remove the salt once it has entered, it is only removed by transportation elsewhere or can be diluted with fresh water to less harmful levels. It is found that one teaspoon of salt is enough to pollute 5 gallons of water permanently. This means salt we put on our roads will effect ecosystems for years to come and it doesn't take much to cause long-lasting damage.
Not only does salt affect our surrounding ecosystems but it is affecting our groundwater and wells we rely on for drinking water. A 2008 study done on 125 wells found nearly half had salt concentrations higher than what is considered a safe by the EPA. Like with ecosystems, salt can remain in our groundwater for many years and can increase in concentration even after we stop using it. Salt is also very corrosive to our vehicles and infrastructure causing billions of dollars of estimated damage yearly in the US.
As bad as all of this sounds, we unfortunately do not have a better alternative at the moment. Sand is sometimes used in a mixture with some salt but it also has indirect environmental and infrastructure impacts from sedimentation. The best solution is moderation. Not over-applying salt can lessen its impact as well as keep roads and walkways safe to travel. This can be implemented by private homeowners as well as public workers. Towns and transportation departments can have management plans in place to make sure they are applying the salt in the most efficient manner which includes continuous training of those actually applying the salt. To all who have read this far the take away message is be conscious of how much salt you are using and try to use less for our and the ecosystem's health. Below are articles with further information and research.
https://www.caryinstitute.org/sites/default/files/public/reprints/report_road_salt_2010.pdf
https://www.bridgestonetire.com/tread-and-trend/tire-talk/pros-and-cons-of-using-road-salt-in-winter
https://blogs.ei.columbia.edu/2018/12/11/road-salt-harms-environment/
Salt used for the roadways and sidewalks is most commonly the unrefined version of our table salt! Salt reduces the freezing point of water meaning it will take temperatures lower than 32 degrees Fahrenheit to make salt water freeze. Salt does need water to mix with so you might ask "How does putting it on ice make it melt?" Well, ice actually has a very small film of water on it allowing the salt to lower the freezing point and begin melting some of the ice creating more water to mix with and so on. However, this does take time so oftentimes road departments will try to pre-treat roads to avoid ice forming in the first place.
Now that we know the process behind the magic let's discuss the environmental implications salt has. When the salt washes off our roads and sidewalks it eventually makes its way to our streams or aquifer system. Runoff with high salt concentrations will be dense compared to freshwater and will sink to the bottom. This can cause oxygen depletion in the ecosystem as the saltwater layer will restrict gas exchange. A 2014 study also found that many urban streams had high levels of chloride, which is toxic to aquatic life. Chloride disrupts aquatic organisms growth and reproduction, food sources, and amphibians ability to maintain water and salt amounts in their bodies (osmoregulation). Unfortunately, ecosystems also don't have a biological process to remove the salt once it has entered, it is only removed by transportation elsewhere or can be diluted with fresh water to less harmful levels. It is found that one teaspoon of salt is enough to pollute 5 gallons of water permanently. This means salt we put on our roads will effect ecosystems for years to come and it doesn't take much to cause long-lasting damage.
Not only does salt affect our surrounding ecosystems but it is affecting our groundwater and wells we rely on for drinking water. A 2008 study done on 125 wells found nearly half had salt concentrations higher than what is considered a safe by the EPA. Like with ecosystems, salt can remain in our groundwater for many years and can increase in concentration even after we stop using it. Salt is also very corrosive to our vehicles and infrastructure causing billions of dollars of estimated damage yearly in the US.
As bad as all of this sounds, we unfortunately do not have a better alternative at the moment. Sand is sometimes used in a mixture with some salt but it also has indirect environmental and infrastructure impacts from sedimentation. The best solution is moderation. Not over-applying salt can lessen its impact as well as keep roads and walkways safe to travel. This can be implemented by private homeowners as well as public workers. Towns and transportation departments can have management plans in place to make sure they are applying the salt in the most efficient manner which includes continuous training of those actually applying the salt. To all who have read this far the take away message is be conscious of how much salt you are using and try to use less for our and the ecosystem's health. Below are articles with further information and research.
https://www.caryinstitute.org/sites/default/files/public/reprints/report_road_salt_2010.pdf
https://www.bridgestonetire.com/tread-and-trend/tire-talk/pros-and-cons-of-using-road-salt-in-winter
https://blogs.ei.columbia.edu/2018/12/11/road-salt-harms-environment/
This image shows a truck spreading a deicer on a roadway. A very common sight this time of year.