Improving the phytoremediation efficiency of soil phenanthrene contamination by addition of exogenous laccase with soil temperature regulation.

Polycyclic aromatic hydrocarbons (PAHs) pose a significant threat to ecosystem security and human health. Laccase, a copper-containing oxidase, can oxidize aromatic compounds, potentially enhancing soil organic contaminants degradation and reducing secondary pollution risks in phytoremediation. However, the combined effects of laccase addition and soil temperature on phytoremediation efficiency remain underexplored. This study investigated laccase-assisted phytoremediation of phenanthrene (PHE)-contaminated soil and examined the role of temperature by setting four maize cultivation temperatures: ambient temperature (about 23 °C), 26 °C, 28 °C and 30 °C. The research aimed to optimize phytoremediation strategies by understanding the interplay between laccase activity, plant growth, rhizosphere microbial system, and soil temperature. The results showed that laccase addition significantly improved remediation efficiency of PHE-contaminated soil, and the highest PHE removal efficiency of 74.41 % was achieved at 26 °C soil temperature, while the PHE content in maize leaves and roots was markedly reduced by 20.26 % and 20.24 %, respectively. Moreover, the results indicated that laccase addition and temperature regulation could promote plant growth, increase maize ion homeostasis and regulate soil microbiological system, including soil enzyme activity, nutrient content and microbial community structure, thus improving phytoremediation efficiency and plant biosafety. Overall, this study investigated the potential mechanisms to improve phytoremediation efficiency through laccase addition and temperature regulation, providing a feasible approach for more effectively degrading organic pollutants under different temperature conditions.