Phytoremediation Using Willow in Industrial Contaminated Soil

Abstract

In our previous work, we used Salix viminalis in the field to decontaminate agricultural soils containing cadmium. Our aim in the current study was to determine whether S. viminalis could decrease the levels of heavy metals, arsenic, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in industrial soil at a former workshop site. The site was planted with S. viminalis cuttings in July 2003. Soil samples were collected yearly from 2005 to 2015 and analysed for heavy metals, arsenic, PCBs and PAHs. The results showed that 21% of chromium, 30% of arsenic, 54% of cadmium, 61% of zinc, 62% of copper, 63% of lead, 87% of nickel, 53% of PCBs and up to 73% of PAHs were removed from the soil after 10 years of S. viminalis treatment. After just 1 year of Salix cultivation, a significant decrease was observed in most of the contaminants in the soil. The reduction in contaminants was linear at first but slowed down after a few years. The number of years prior to a slow-down in rate of removal differed between the contaminants. This study concludes that S. viminalis can be used for the phytoremediation of contaminated industrial soil and that the rate of decontamination differs between substances.