Abstract
The application of NaCl as a deicer increases salinity of stormwater runoff, which may impact the speciation and mobility of various contaminants, including metals. Salt can remain in the fill media of stormwater management practices for an extended period after application, creating annual cycles of baseline and high salinity. This study evaluated the impacts of NaCl concentration and application cycles on metal retardation in fill media via 1-D continuous flow bench-scale columns. The high salinity scenario of 0.1 M NaCl decreased retardation factors of metals when compared to baseline salinity scenario of 0.01 M NaCl. Application of cycling baseline and high NaCl caused substantial fluctuations in the effluent metal concentration. The metals that were adsorbed during the baseline salinity periods were desorbed during the high salinity periods, leading to elevated concentrations of metals in porewater and effluent. Flushing with water removed only Na from the fill media top layers, while applying cysteine, as an environmentally friendly chelator, was demonstrated to be a promising approach to mobilizing accumulated metals from top layers to deeper layers. The results suggest that incorporating seasonal changes in environmental variables such as salinity enhances accuracy of contaminant transport modeling in fill media.
Published Version
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