Roads turned white, cars dusted with salt, and floors marred by powdery footprints—these are common sights during winter in the United States. While road salt helps to manage icy conditions, its extensive use has far-reaching consequences on the environment, infrastructure, and public health.
Dr. Steven Goldsmith, a Villanova University professor specializing in watershed biogeochemistry, has been leading research into the effects of de-icing practices on water quality. He recently discussed the significant impacts of road salt and explored potential strategies for mitigating its damage.
Environmental and Health Concerns
In a 2022 study, Dr. Goldsmith’s team uncovered that sodium from road salt is entering Philadelphia’s water supply, especially during snowmelt periods. In winter 2018-19, sodium levels in tap water were found to be six times higher than the Environmental Protection Agency’s recommendation for a low-sodium diet. The problem persists throughout the year as salt-contaminated groundwater continues to elevate sodium levels.
Additional findings from another study highlight how road salt seeps into soil and shallow groundwater, ultimately reaching streams. This runoff often mirrors seawater salinity, posing a threat to freshwater species.
Beyond Sodium: Chloride and Heavy Metals
Chloride from road salt is also a concern, as it can harm aquatic organisms and corrode drinking water infrastructure. This corrosion can release harmful metals like lead into the water supply, raising human health risks. Salt also displaces positively charged elements in soil, potentially increasing the presence of heavy metals such as copper and zinc in nearby streams.
Brine: A More Effective Alternative
Dr. Goldsmith advocates for the use of brine as a more efficient de-icing solution. Brine, a mixture of road salt and water, penetrates the pavement, preventing ice formation. It sticks better to surfaces, reducing both the amount of salt used and the frequency of reapplication.
Studies suggest that adopting brine could reduce salt runoff by 23 to 40 percent, significantly benefiting aquatic life and lowering costs associated with salt application.
Reducing Salt Use: Individual and Municipal Actions
Households and private contractors often contribute more to salt runoff than road applications. The excessive use of salt on private properties is often driven by legal concerns and social norms. Dr. Goldsmith recommends using a coffee mug’s worth of salt for every 10 sidewalk squares as a practical guideline.
Alternatives to road salt, such as sand and beet juice, also have environmental drawbacks. While some road salt is necessary, the focus should be on using it more judiciously.
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