Riparian soils and vegetation are under intense pressure from various anthropogenic sources and heavy metal pollution seriously contributing to multiple stress conditions. In order to determinate the extent of pollution in the riparian zone of the Sava River, bioavailability of heavy metals in soils and metal uptake by Salix alba L. were measured. The study area covered about 200 km of the Sava River stretch, through Slovenia, and included 5 sampling sites (Mojstrana, Radovljica, Litija, Vrhovo and Čatež).

To estimate heavy metal content and potential ecological risk on riparian soil, total and bioavailable concentrations of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn) were analysed and the Risk Assessment Code (RAC) was calculated. RAC revealed that Cr, Cu, and Ni come under the no risk category (<1%) and Zn comes under the low risk category (<10%) for the environment at all the sampling sites. According to RAC, bioavailable concentrations of Cd indicated high risk (30-50%) for the environment in Mojstrana and Radovljica sites, and medium risk (<30%) for the environment in Litija, Vrhovo, and Čatež sites.

In order to assess whether Salix alba is suitable for remediation of polluted riparian soil, concentration, transfer, and accumulation of heavy metals from soil to roots and leaves in terms of the Biological Concentration Factor (BCF) and the Translocation Factor (TF) were evaluated. The study indicates that Cr and Ni accumulated by the willow trees were largely retained in roots (TF<1), whereas Cd, Cu, and Zn were accumulated in leaves, as the TF value was found to be >1 at the most sampling sites. Our results of BCFs and TFs showed that Salix alba trees limit mobility of Cr and Ni since TF is <1, which makes this species potentially suitable for phytostabilisation of chromium and nickel. BCF and TF for cadmium, copper, and zinc indicates willows potential for phytoextraction of these trace elements.