Application risk and value of Cd-enriched poplar wood: Wood properties, leaching characteristics and brown rot resistance

This study investigated the application risk and value of Cd-enriched poplar wood, focusing on its wood properties, leaching characteristics, and brown rot resistance. The results indicated that Cd deposition in cell walls significantly inhibited brown rot fungi, thereby enhancing decay resistance. Furthermore, the extent of improvement in brown rot resistance was linked to wood density: the higher the density of Cd-enriched poplar wood, the stronger its resistance to brown rot. As the Cd concentration increased, the Cd distribution abundance and the wood crystallinity gradually increased. Structural changes were observed, including fluctuating microfibril angle and double wall thickness of fibers and vessels. Cd concentrations exceeding 50 mg/kg altered the chemical composition of the cell walls. The binding form of Cd in wood cell wall showed a trend of bound Cd ＞ free Cd ＞ residual Cd. Cd leaching occurred under cyclic soaking in water, which may lead to secondary contamination. However, under the condition of 75 % relative humidity, Cd leaching was negligible, suggesting potential for safer use in controlled environments. These findings provide valuable insights into the management and application of Cd-enriched wood, especially in contexts where decay resistance is critical or in water-exposed environments.