The use of oxytrees in the purification of the soil and water environment in the area of municipal waste landfills

Abstract

Municipal waste landfills are an important source of soil and water pollution due to the generation of leachates rich in heavy metals, salts, and organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). Conventional remediation methods are expensive, sparking interest in phytoremediation as a sustainable alternative. This study evaluates the potential of Paulownia tomentosa (oxytree) in remediating soils contaminated by landfills. Seedlings were grown under controlled conditions and irrigated with distilled water, 50% landfill leachate, and 100% landfill leachate. Chemical analysis of the soil, roots, stems and leaves revealed the selective accumulation of macronutrients (particularly nitrogen and phosphorus) and selected potentially toxic elements (such as lead, zinc and copper), with the contaminants primarily retained in the roots. Stress biomarkers indicated significant physiological responses, including increased proline levels and decreased phenol and flavonoid content, reflecting plant stress under elevated leachate exposure. Notably, P. tomentosa demonstrated the ability to reduce 4- and 5-ring PAH concentrations, particularly at moderate leachate levels. However, its overall remediation effectiveness was limited in comparison to phytoremediation grasses, which exhibit stronger contaminant removal potential. These results indicate the limited suitability of Paulownia for landfill remediation, emphasizing the need to optimize leachate concentrations.