Road salt applications mobilize trace elements from roadside soil to shallow groundwater

Area of Science:

• Environmental Science
• Geochemistry
• Hydrology

Background:

• Road deicing salts can mobilize soil micronutrients and toxic trace elements.
• These mobilized elements can contaminate surface and groundwater, impacting ecosystems and water resources.
• Understanding the dynamics of trace element release is crucial for managing water quality.

Purpose of the Study:

• To quantify the timing and extent of trace element release from soil to porewater and groundwater due to deicing events.
• To compare trace element mobilization in rural versus urban settings.
• To evaluate the role of land use in the transport of deicing-related contaminants to groundwater.

Main Methods:

• Soil porewater and karst spring water sampling for trace element, sodium (Na), and chloride (Cl) analysis.
• Correlation analysis between salt application, Na/Cl levels, and trace element concentrations.
• Comparison of contaminant levels at rural and urban sites.

Main Results:

• Trace elements (As, Ba, Fe, Sr) in soil porewater at a rural site peaked with Na and Cl after deicing events.
• No significant trace element increases were observed in a rural karst spring, likely due to low deicer input.
• Urban karst springs showed trace element (As, Cu, Li) peaks with deicing pulses, and significant correlations between salt application and trace element export were found.

Conclusions:

• Road salt application drives the release of trace elements from soil into soil porewater and groundwater.
• Urbanization exacerbates the release and transport of these deicing-related trace element contaminants.
• Land use significantly influences the pathways and extent of trace element contamination in groundwater systems.