DATE: February 6, 2019
SNIP: Gene Likens has been studying forest and aquatic ecosystems for more than half a century. In that time he’s seen a change in the chemistry of our surface waters — including an increase in the alkalinity and salinity of waterways — something he and his colleagues have dubbed “freshwater salinization syndrome.”
Likens coauthored a report published last month that found that not only is salinity increasing in many surface waters, but when you add salt to the environment it can mobilize heavy metals, nutrient pollution and other contaminants that are combining to create new “chemical cocktails” in rivers, streams and reservoirs.
“I didn’t expect the massive scale of change across the lower 48 that we found — or the magnitude of change,” says Likens, who is president emeritus of the Cary Institute of Ecosystem Studies and a distinguished research professor at the University of Connecticut.
Salt on its own has been shown to be problematic. Too much of it in the water can be a health risk for someone with hypertension, says Likens. And salts washing off roadways have been shown to damage or kill vegetation. It can also seep into drinking water wells. High enough levels of salinity can be toxic to some aquatic life, too, says Likens.
Other new research has honed in on this threat from salt. “Increased salinity in freshwater systems is expected to cause extensive changes in biota and potentially in ecological function, and some losses of freshwater resources,” freshwater scientist John R. Olson from California State University Monterey Bay wrote in a recent study.
Salts, Kaushal and his colleagues found, can liberate heavy metals and other elements in soils and concrete surfaces, which can be more dangerous when mixed together than any one of them singly. Salts can also mobilize nitrates, stimulating harmful algal blooms that threaten the health of fish and other marine organisms.
Kaushal and his colleagues analyzed streams near the University of Maryland after a snowstorm and found spikes in the concentration of metals like copper, zinc, manganese and cadmium.
And after a storm salt concentrations can stay elevated for months, increasing the amount of time that the salts can draw these chemical cocktails out of the soil and into waterways.