Willows Used for Phytoremediation Increased Organic Contaminant Concentrations in Soil Surface

The Salix genus includes shrub species that are widely used in phytoremediation and various other phytotechnologies due to their advantageous characteristics, such as a high evapotranspiration (ET) rate, particular when cultivated short rotation intensive culture (SRIC). Observations made past field studies suggest ET its impact on soil hydrology can also lead increases pollutant concentrations near shrubs. To investigate this, sections of mature willow plantation (seven years old) were cut eliminate transpiration (Cut treatment). Soil polychlorinated biphenyls (PCBs), aliphatic compounds C10–C50, polycyclic aromatic hydrocarbons (PAHs) five trace elements (Cd, Cr, Cu, Ni Zn) compared between the Cut uncut plots (Salix miyabeana ‘SX61’). Over 24 months, results clearly show removal shrubs limited contaminants’ increase surface, observed for C10–C50 10 PAHs under treatment. This finding strongly reinforces hypothesis SRIC willows may facilitate migration contaminants towards roots, thus increasing concentration surrounding soil. Such “pumping effect” high-density crop is prominent characteristic specific counterintuitive results. Although apparent contaminant contradict purification benefits usually pursued phytoremediation, possibility active phytoextraction rhizodegradation not excluded. Moreover, following decreases would consequently occur at source points. Some reflections interpreting work provided.