Nutrient-assisted phytoremediation of wood preservative-contaminated technosols with co-planting of Salix interior and Festuca arundinacea.

The remediation of wood preservative-contaminated sites is an important issue due to the carcinogenic nature of some contaminants derived from wood preservatives (e.g., Cr+6, arsenate, and pentachlorophenol). This study evaluated the effects of fertilizer application on remediation potential of co-plantings of Salix interior Rowlee. (Salix) and Festuca arundinacea Schreb. (Festuca) in a wood preservative-spiked technosol while considering the potential contaminant and nutrient leaching. Two levels of nitrogen (N) and phosphorus (P) fertilizers, NaNO3 and NaH2PO4 (25 and 75 mg L-1), were applied to achieve three N:P ratios, i.e., 3:1 (75:25), 1:3 (25:75), and 1:1 (25:25), that were compared with a control treatment (0:0 N:P) in a mesocosm experiment. Roots of the plant supplied with 1:1 and 1:3 N:P had more than double arsenic (As) and copper (Cu) amounts (i.e., biomass × concentration) compared to the control ones. Highest As and Cu amounts in shoots were found for Salix stems and Festuca leaves in the 1:3 and 1:1 N:P treatments, respectively. Arsenic and P leaching was high in mesocosms supplied with 1:3 N:P. Contamination and nutrient leaching in the 1:1 N:P treatment did not differ from the control, except for Cu. In conclusion, 1:1 N:P treatment yielded the best results in terms of metal(loid) uptake and contaminant and nutrient leaching. In 1:1 N:P treatment, the maximum values of percent As, Cr, and Cu in Salix and Festuca aboveground were 0.18%, 0.024%, and 1.20% and 0.89%, 0.08%, and 1.78%, respectively.