EFFECT OF DEICING SALTS ON METAL AND ORGANIC-MATTER MOBILIZATION IN ROADSIDE SOILS

Roadside soils were sampled from areas that receive heavy traffic and deicing salts. These soils were leached in columns at 6-degrees-C with solutions of NaCl, calcium magnesium acetate (CMA), or deionized water to simulate the runoff of salty water from a roadway followed by snowmelt or rainwater. In the salt solution leachates, the concentrations of Cr, Pb, Ni, Fe, Cd, and Cu tended to increase with increasing salt concentration, suggesting that ligand complexation and competitive exchange affected mobilization. In the soils leached initially with NaCl, followed by deionized water, extensive mobilization of organic matter and elevated concentrations of Cr, Pb, Ni, Fe, and Cu were observed. The dominant mechanism controlling metal mobilization was dispersion of organic matter under conditions of high exchangeable Na and low electrolyte concentration.