The increasing applications of single-layer molybdenum disulfide (SLMoS2) pose great potential risks associated with environmental exposure. This study found that metallic-phase SLMoS2 with nanoscale (N-1T-SLMoS2, ∼400 nm) and microscale (M-1T-SLMoS2, ∼3.6 μm) diameters at 10–25 mg/L induced significant algal growth inhibition (maximum 72.7 and 74.6%, respectively), plasmolysis, and oxidative damage, but these alterations were recoverable. Nevertheless, membrane permeability, chloroplast damage, and chlorophyll biosynthesis reduction were persistent. By contrast, the growth inhibition (maximum 55.3%) and adverse effects of nano-sized semiconductive-phase SLMoS2 (N-2H-SLMoS2, ∼400 nm) were weak and easily alleviated after 96 h of recovery. N-1T-SLMoS2 (0.011 μg/h) and N-2H-SLMoS2 (0.008 μg/h) were quickly biodegraded to soluble Mo compared with M-1T-SLMoS2 (0.004 μg/h) and excreted by algae. Incomplete biodegradation of SLMoS2 (26.8–43.9%) did not significantly mitigate its toxicity. Proteomics and metabolomics indicated that the downregulation of proteins (50.7–99.2%) related to antioxidants and photosynthesis and inhibition of carbon fixation and carbohydrate metabolism contributed to the persistent phytotoxicity. These findings highlight the roles and mechanisms of the size and phase in the persistent phytotoxicity of SLMoS2, which has potential implications for risk assessment and environmental applications of nanomaterials.

Salix matsudana Koidz was exposed to different concentrations of Cd (0, 10, 50, and 100 µmol/L) to study the effects of Cd on mineral metabolism and antioxidant enzyme activities. The results showed that plant height and root length were inhibited by 50 and 100 µmol/L Cd, except the one under 10 µmol/L Cd treatment. The Cd content accumulated in different organs of S. matsudana, gradually increasing with increased Cd concentrations and prolonged treatment times. The root was the main organ for absorbing and accumulating Cd. Cd inhibited the accumulation of Fe, Zn, Mn, and Cu. In addition, the activities of antioxidant enzymes and the contents of reactive oxygen species were also changed by different concentrations of Cd. The results obtained here can provide scientific and objective data for the use of S. matsudana in the remediation of Cd-contaminated soil.

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