The application of deicing salt reduces the potential for weather-related travel accidents on roads and walkways during winter but increases the potential for freshwater quality degradation as these chemicals are washed into waterways. Researchers from the University of Maryland and University of Connecticut have labeled the cascading effects of introduced salts Freshwater Salinization Syndrome (FSS), which exerts detrimental impacts on drinking water quality, human health, agriculture, infrastructure and wildlife.

An analysis of the scope and magnitude of FSS, published in Biogeochemistry, reveals a general increase in chloride concentrations on a global scale. A 30-year trend of increasing salinity is observed in places like the Passaic River in northern New Jersey and a 100 mile plus stretch of the Potomac River that supplies drinking water to Washington, D.C. Road salts are a major contributor but other sources include sewage leaks and discharges, water softeners, agricultural fertilizers and fracking brines enriched with salts. Indirect sources of salts in freshwater identified include weathering roads, bridges and buildings.

Data document FSS on a global scale in terms of increasing chloride trends in freshwaters. Source: Sujay S. Kaushal et al.

Management strategies must consider salt contributions from these different sources on a watershed-ecosystem level and prioritize regulation accordingly. The researchers also stress the need to increase water monitoring initiatives and apply modern sensor technology to capture continuous data. High-frequency sensor data can be of value in detecting peaks in salinity and water flow and in predicting the accumulation of toxins due to FSS.