roadways

Native plants and road salt pollution

February 12, 2025 By EarthWise Leave a Comment

Applying salt to roadways lowers the freezing point of water and prevents slippery surfaces, which makes it safer for people to drive in wintry conditions. In the U.S., more than 22 million tons of road salt is spread every year.

But road salt harms infrastructure and the environment. In fact, road salt damages cars and metal infrastructure by accelerating rust and corrosion. Road salt can also leach into soil and waterways, disrupting ecosystems, degrading soil, contaminating water, and damaging vegetation.

In cities and towns, road salts often wash into stormwater systems, posing health concerns and challenges for infrastructure.

A new study led by researchers from Virginia Tech looked at how salt affects plants and whether certain plants could mitigate salt pollution. The research team studied stormwater detention basins in Northern Virginia, examining the impacts of road salt on plants, soils, and water quality in green infrastructure systems.

The findings, which were recently published in the journal Science of the Total Environment, found that the amount of salt present in green infrastructure systems does reach levels that threaten plant communities. However, the researchers found that relying on salt-tolerant plants for mitigation is unlikely to be effective because they simply don’t take in enough salt.

Certain plants, particularly cattails, absorbed substantial amounts of salt. But even in a basin densely planted with salt-tolerant cattails, only up to 6% of the road salt applied during winter could be removed.

Plants alone cannot solve our salt pollution problem.

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Researcher studies the power of native plants to combat road salt pollution

Photo, posted January 22, 2025, courtesy of the City of Greenville, North Carolina via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Self-heating concrete

April 24, 2024 By EarthWise Leave a Comment

States in the colder parts of the country spend an estimated $2.3 billion a year on snow and ice removal as well as untold millions on repairing roadways damaged by winter weather. Researchers at Drexel University have been researching a way to extend the service life of concrete surfaces like roadways and to help them maintain a surface temperature above freezing during the winter.

Preventing freezing and thawing as temperatures go up and down and reducing the amount of plowing and salting is a desirable goal. The Drexel team has developed a cold-weather-resilient concrete mix that is capable of melting snow on its own using only the thermal energy in the environment and not requiring salt, shoveling, or heating systems.

The system uses low-temperature liquid paraffin that turns from its room-temperature liquid state into a solid when temperatures go down. Incorporating the liquid paraffin into concrete triggers heating when temperatures drop due to the energy released by the phase change.

Tests on slabs of the concrete on the Drexel campus over the past two years recorded 32 freeze-thaw events. The special slabs maintained a surface temperature between 42 and 55 degrees for up to 10 hours when air temperatures dipped below freezing.

The heating is enough to melt a couple of inches of snow at a rate of a quarter inch an hour. It’s not enough to melt a heavy snow event before plows are needed, but it can help deice road surfaces and increase transportation safety. And simply preventing the surface from freezing, thawing, and refreezing can go a long way towards preventing deterioration. It is promising research toward reducing an ongoing problem in colder climates.

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Drexel’s Self-Heating Concrete Is One Step Closer to Clearing Sidewalks Without Shoveling or Salting

Photo, posted March 16, 2024, courtesy of Ajay Suresh via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Solar Parking Lots In France | Earth Wise

January 6, 2023 By EarthWise Leave a Comment

France has passed legislation that will require all parking lots with more than 80 spaces to be covered over by solar panels. This is part of a broader effort to put solar panels on vacant lots, empty land alongside roadways and train tracks, and even some farmland. The overall program would add 11 gigawatts of solar power to the French electricity grid.

The legislation applies to both new and existing parking lots. Owners of parking lots with more than 400 spaces would have 3 years to comply, while owners of lots with 80 to 400 spaces would have five years.

To produce 11 gigawatts of solar output, about half a percent of France’s urban land would need to be covered with solar panels. This is quite a bit, but not an insurmountable obstacle. Parking lots, however, could only provide a fraction of what is needed. It would take something like 8 million parking spaces covered with solar panels to produce that much power. That is probably at least twice as many as France has.

Several countries, most notably Germany, already have mandates for new construction to incorporate renewable energy. This includes solar panels, biomass boilers, heat pumps, and wind turbines. Many parking lots in southern Europe already have sunshades over them, which would make it pretty easy to install solar panels. This is much rarer in cooler countries.

France is pursuing this policy to reduce its dependence on nuclear power, which currently provides 70% of the country’s electricity. Apart from the general trend of opposition to nuclear power, reliance upon it during increasingly common droughts is problematic as the power plants require significant amounts of water to operate.

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France’s plan for solar panels on all car parks is just the start of an urban renewable revolution

Photo, posted February 11, 2008, courtesy of Armando Jimenez / U.S. Army Environmental Command via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sand From Mining Waste | Earth Wise

May 10, 2022 By EarthWise Leave a Comment

The natural resources people use the most are air and water. It may come as a surprise that in third place is sand. Sand is used to make glass, computer chips, toothpaste, cosmetics, food, wine, paper, paint, plastics, and more. It is estimated that 50 billion tons of sand are used each year.

Concrete is 10% cement, 15% water, and 75% sand. The concrete required to build a house takes on average 200 tons of sand, a hospital uses 3,000 tons, and a mile of a highway requires 15,000 tons.

One would think that there is no shortage of sand, but we are using it up faster than the planet can make it and the extraction of sand from seas, rivers, beaches, and quarries has negative impacts on the environment and surrounding communities. For example, removing sand leads to erosion in riverbanks, significantly increasing the risk of flooding in some places.

A potential strategy to reduce the impact of extracting sand to meet society’s growing need for is also a strategy for helping to reduce the production of mineral mining waste, which is the largest waste stream on the planet. Mining produces between 33 and 66 billion tons of waste material each year.

A new study by researchers in Switzerland and Australia looked at the potential for using mining waste as a source of so-called ore-sand. Sand-like material left over from mining operations could be used for many current applications for sand. Separating and repurposing these materials before they are added to the waste stream would not only reduce the volume of waste being generated by mining operations but would also create a responsible new source of sand.

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Solution to world’s largest waste stream: Make sand

Photo, posted October 22, 2005, courtesy of Alan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

De-Icing Roadways

February 9, 2016 By WAMC WEB

We have been using salt to keep winter roads free of ice and snow since the late 1930s. In the United States alone, some 20 million tons of salt are applied to roadways each year. And while its use has real benefits in terms of safety and navigation, there have been cumulative costs to the environment, including degrading freshwater resources and contaminating groundwater.

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