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 x 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.

Automated summary

This study investigated the effects of fertilizer application on the remediation potential of co-plantings of Salix interior Rowlee and Festuca arundinacea Schreb. in wood preservative-contaminated soil. The results showed that a 1:1 nitrogen-to-phosphorus ratio treatment yielded the best results in terms of metal(loid) uptake and contaminant and nutrient leaching, with increased arsenic and copper uptake in the plant roots. High arsenic and copper amounts were found in both Salix and Festuca in specific nitrogen-to-phosphorus ratio treatments.