Student team explores impact of road salt on streams and soils

Sampling revealed that road salt never left the local ecosystem completely. “[We learned that] the effects of road salt application last all year long,” the report says. “This is an important finding, given that stream flow often reaches its minimum in summer and … is more sensitive to increases in salinity if chloride continues to be discharged from storm water outfalls or groundwater during this time.”

Findings like these are not unique to Ithaca. Recent research by the U.S. Geological Survey and others indicates that chloride concentrations – attributed to road salt usage – are rising in streams across the northern United States.

Lauren McPhillips, a Cornell doctoral candidate in the field of biological and environmental engineering, examined detention basins that capture storm runoff from campus parking lots. Winter melt water or storm runoff carry road salt from the parking lots to storm water detention basins, where it accumulates in the soil.

Near two slow-draining basins, McPhillips found levels in soils considered to be “saline.” The researchers learned that it took several months for salinity to return to lower baseline levels. McPhillips wondered if these extra-salty parts of campus were uniquely different from other parts of campus. While this research is still in progress, she did discover that some microbial activities were significantly elevated in the wet, salty detention basins, indicating that soil microbes may be adapting to the saltier conditions.

The most obvious solution is to use less road salt, explained Walter, but this would come at the cost of increased traffic hazards. Walter notes that Cornell Facilities Services has been proactive in experimenting with storm water management strategies and enthusiastic about his students monitoring campus. “The first step to finding better ways to manage our infrastructure is to measure how our activities are impacting the environment,” said Walter.

Pete Salino, director of Cornell’s grounds department, said that the university uses “cultural and mechanical practices” to decrease salt use on roads, sidewalks and steps. For example, some paths and stairways are not maintained during the winter, and the department uses rate-controlled spreaders. Front-mounted brooms for sidewalk snow-removal equipment rid slush from the walkway without salt.

Quite interested in this research, David Cutter, the university’s landscape architect, said this research is useful, as he looks for ways to address water runoff. Cutter hopes to experiment using “bioswales” – ditches with vegetation – to employ plants that may store salt in their tissues in order to remove it from the environment.

The undergraduate research project was funded by a grant from the Engineering Learning Initiative program at Cornell. The National Science Foundation/ Integrative Graduate Education and Research Traineeship and the New York State Water Resources Institute funded McPhillips’ work.

This article was originally published in the Cornell Chronicle.