Data loggers purchased by the Pennsylvania Department of Transportation measured the level of salt in and near one of those wetlands for three years. Silver analyzed the data, and sediment from the bottom of the wetlands, to assess the impact on non-biting midges, which live in marshy conditions.
“Midges are a good indicator species,” Silver explains. “They’re easy to cultivate, their biology is well understood, and they live in the mud. If salt is going to accumulate, it will be there, in the sediment. We can see how it affects them.”
Two years after the road opened, there were significantly fewer midges in the wetland designed to receive the runoff than in other constructed wetlands that were kept free of salt.
Silver would like to know the impact elevated salt concentrations have on other strands of the food web, including algae, salamanders, frogs, and fish. “Salinization of fresh water can cause immense ecological harm,” she says. “All of the natural services that fresh water provides, including photosynthesis and the processing of leaf material — the processes that are not on our radar, but that keep us alive — are directly affected by it.”
There is an economic cost as well: Recreational fishing is a $1.3 billion business in Pennsylvania, according to the state’s Fish and Boat Commission. That disappears if the habitat can no longer sustain fish.
For now, however, Silver is focused on the salt runoff across Penn State Behrend’s 854-acre campus. “If we can put the pieces together here,” she says, “we will have a far more complete picture of the impact this salt is having on our environment, including our drinking water. If we can develop new methods for containing it, or for using it more efficiently, and we can point to that success, other, larger entities, including municipalities, might follow suit.”
Seeing the problem
“To fix a problem, you have to first see it,” says Michael Naber, a lecturer in geosciences. With help from Devin Beggs, a science major, Naber mapped the conductivity levels that Silver and her students recorded over a six-week period last winter. That data, drawn from the 110 sampling sites, allowed him to predict the presence of salt elsewhere on campus.
“People know this stuff’s out there,” he says. “They see it on their cars and their boots and on the carpets when they enter a building. What’s eye-opening is how concentrated it is in some areas.”
On his map, the small parking lot near Glenhill Farmhouse is alarm-button red. Some snow samples collected there had conductivity rates of more than 44,000 microsiemens/cm, which is 40 times the safe level for drinking water. At that concentration, the salt kills grass, algae, midges, and fish.