Saltier waterways are creating dangerous ‘chemical cocktails’

New UMD-led research highlights the need for better regulation and pollution management strategies.

Salt applied to roadways as a wintertime deicer has been shown to make significant contributions to increased salinity in freshwater streams in the United States, Europe and elsewhere. New research suggests that saltier water also liberates toxic metals and harmful nitrogen-containing compounds from streambeds and soils, creating dangerous
Salt applied to roadways as a wintertime deicer has been shown to make significant contributions to increased salinity in freshwater streams in the United States, Europe and elsewhere. New research suggests that saltier water also liberates toxic metals and harmful nitrogen-containing compounds from streambeds and soils, creating dangerous "chemical cocktails" that can be more damaging than individual pollutants alone. CREDIT Joseph Galella/University of Maryland

A cocktail of chemicals from many human activities is making U.S. rivers saltier and more alkaline across the nation. Surprisingly, road salt in winter is not the only source: construction, agriculture, and many other activities also play roles across regions.

An ongoing study driven by University of Maryland specialists found that streams and rivers over the United States have turned out to be saltier and more antacid in the course of recent years, because of street deicers, fertilizers and other salty exacerbates that people indirectly release into rivers.

Scientists took a gander at the global, regional and local consequences of Freshwater Salinization Syndrome. Scientists found that salty, alkaline freshwater can discharge an assortment of chemicals, including poisonous metals and toxic nitrogen-containing compounds from streambeds and soils in waste bowls.

The outcomes further recommend that a significant number of these synthetic substances travel together all through watersheds, framing chemical cocktails” that can have all the more annihilating impacts on drinking water supplies and ecosystems when contrasted and singular contaminants alone.

Studying further, they enlighten the need for new and more comprehensive regulation and pollution management strategies. They determined the impacts of chemical cocktails created by saltier water in more detail.

They accessed previously published data from rivers in the U.S., Europe, Canada, Russia, China, and Iran, substantially expanding the geographic boundaries of the researchers’ previous work.

Their analysis suggests that Freshwater Salinization Syndrome could be a global phenomenon, with the most conclusive support showing a steady trend of increased salt ions in both U.S. and European rivers. These trends trace back at least 50 years, with some data reaching back far enough to support a 100-year trend.

Study co-author Gene Likens, president emeritus of the Cary Institute of Ecosystem Studies said, “Given what we are finding, I continue to be surprised by the scope and magnitude of the recent degradation of Earth’s surface waters. The formation of novel chemical cocktails is causing deterioration far beyond my expectations.”

In the snowy Mid-Atlantic states and New England, road salt applied to roadways in winter is a primary cause of Freshwater Salinization Syndrome. Kaushal and his colleagues took a deeper dive into the chemical consequences of road salt by performing detailed field studies in streams located near Washington, D.C., and Baltimore.

In one set of observations, the researchers sampled water from the Paint Branch stream near the UMD campus before, during and after a 2017 snowstorm. This aspect of the study allowed the team to trace the effects of road salt washed into the streams by the melting snow.

In another series of experiments, the researchers artificially added salt to the Gwynns Falls stream near Baltimore to simulate what happens during a snowstorm and measured copper concentrations in the water before, during and after adding salt. The downstream data showed an instant spike in copper released from the streambed, suggesting a direct connection between the stream’s salt content and copper in the water.

Salt ion concentrations can stay high for months following a storm, Kaushal added. This lengthens the amount of time that salt can draw metals from the soil, resulting in harmful cocktails of metals and salts transported far downstream.

Sujay Kaushal, a professor of geology at UMD and lead author of the study said, “Looking at water quality data over several months in the winter, salt remains high and rarely has a chance to return to baseline before the next storm comes through and more salt is put on the roads. This high salt load not only liberates metals and other contaminants, but there is also evidence that the initial salt pulse releases other salt ions from the streambed and soils, such as magnesium and potassium, which further contribute to keeping overall salt levels high.”

Shahan Haq (B.S. ’14, physical sciences), a geology graduate student at UMD and a co-author of the study said, “To me, this study highlights the need to view salt as an emerging contaminant in freshwater. Salt’s ability to move heavy metals like copper from sediments into the water could have dangerous implications for our drinking water and could be toxic to wildlife. Our observations suggest that some rivers are already at risk, especially here in the eastern U.S. directly following road salt applications.”

The research team published its findings December 3, 2018 in the journal Philosophical Transactions of the Royal Society B.