Cadmium (Cd) pollution is a widespread environmental problem. In this study, we explored the transcriptome and biochemical responses of goldenrain tree (Koelreuteria paniculata Laxm.) leaves and roots to Cd stress. Leaf and root growth decreased substantially under Cd stress (50 mg/L CdCl₂), but leaf and root antioxidant mechanisms were significantly activated. In RNA-seq analysis, roots treated with 25 mg/L CdCl₂ featured enriched GO terms in cellular components related to intracellular ribonucleoprotein complex, ribonucleoprotein complex, and macromolecular complex. In leaves under Cd stress, most differentially expressed genes were enriched in the cellular component terms intrinsic component of membrane and membrane part. Weighted gene co-expression network analysis and analysis of module–trait relations revealed candidate genes associated with superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities and malondialdehyde (MDA). Ten transcription factors responded to Cd stress expression, including those in C2H2, MYB, WRKY, and bZIP families. Transcriptomic analysis of goldenrain tree revealed that Cd stress rapidly induced the intracellular ribonucleoprotein complex in the roots and the intrinsic component of membrane in the leaves. The results also indicate directions for further analyses of molecular mechanisms of Cd tolerance and accumulation in goldenrain tree.

In order to investigate the adsorption characteristics of Cu²⁺, Zn²⁺, and Mn²⁺ on natural diatomite in liquid/solid systems and to provide reliable theoretical support for the application of these materials, we conducted a series of adsorption studies. The results revealed a non-monotonic relationship between the adsorption capacity of natural diatomite and ion concentration. The maximum adsorption capacities for Cu²⁺, Zn²⁺, and Mn²⁺ were found to be 3.56, 6.23, and 3.82 mg·g⁻¹, at concentrations of 200, 500, and 300 mg·L⁻¹. Optimal adsorption conditions were determined by investigating environmental factors such as pH and temperature: pH 6, temperature 30 °C, and contact time 40 min. The adsorption kinetics were found to be in accordance with the pseudo-second-order model (R² > 0.997). Fitting adsorption isotherms for Cu²⁺, Zn²⁺, and Mn²⁺ using various models revealed that the Langmuir (R² > 0.993), Temkin (R² > 0.953), and Freundlich (R² > 0.997) models most accurately describe their adsorption behaviour. Thermodynamic analysis confirmed that adsorption is a spontaneous, endothermic, physical process (ΔG° < 0, ΔH° > 0, ΔS° > 0) and that the overall adsorption rate is limited by micropore adsorption. Consequently, natural diatomaceous earth can serve as an efficient, low-cost adsorbent for removing heavy metals from contaminated water.