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February 11, 2022

A new report connects road salt application (and related increasing salinity in aquifers) to increasing radium concentrations in groundwater through multiple lines of evidence.  

Chloride, sodium, and dissolved solids are the most common contaminants with increasing concentrations across USGS groundwater quality trend networks in the United States. In many areas, the increases are directly related to road-salt application. Chloride and dissolved solids have only non-health guidelines, such as to prevent corrosion of pipes or salty tasting drinking water. However, there is a concern that the changes in aquifer geochemistry may mobilize other contaminants that do have human-health effects. In the Kirkwood-Cohansey aquifer of Southern New Jersey, conditions exist where the increasing salinity could mobilize radium, and the data support a direct causal link between road salt application, increasing salinity, and increasing radium concentrations.

Water managers are typically aware of the potential negative effects of road-salt application and subsequent increases in salinity, but direct links to increases in other contaminants have rarely been documented. In this report, scientists documented increasing radium concentrations in the Kirkwood-Cohansey aquifer in Southern New Jersey. The largest increases in radium were in groundwater with low pH. Low pH can indicate less adsorption of radium onto clay layers, and this adsorption is what controls the concentrations of radium in groundwater. The publication shows through multiple lines of evidence that the increases in radium concentrations are likely to be caused by road salt application.



Plot of Radium concentration vs. road salt application rate
Graph of decadal change in radium concentration vs. road salt application rate (Lindsay and others, 2021). Increases in concentrations of radium are correlated with road-salt application, and multiple lines of evidence support that the relation is causal. 
Image: Ready for Action

A snow plow and road salt application truck clears snow and ice from a roadway to improve traffic and pedestrian safety. The use of salt to deice pavement may be related to increasing radium concentrations in aquifers with low pH. 

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