Toxicological effects of WS2 nanomaterials on rice plants and associated soil microbes

have a wide range of applications. To date, their environmental risks remain largely unknown. In this study, rice plants were grown in soil amended with different concentrations (0,10, and 100 mg/kg) of WS2 NMs for 4 weeks. WS2 NMs at 100 mg/kg significantly increased MDA (malondialdehyde) content and decreased total antioxidant capacities of leaves, indicating the oxidative response induced by WS2 NMs. Meanwhile, WS2 NMs at 100 mg/kg significantly decreased root biomass compared to control, indicating the negative impacts of WS2 NMs on plant growth. While exposure to 100 mg/kg WS2 NMs significantly increased soil bioavailable Cu, Fe, Zn, and Olsen-P, and increased the content of Cu, Fe, Zn, and P in rice leaves. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis showed that W was taken up by rice roots and translocated into leaves. The impact of WS2 on soil microbial communities was evaluated by 16S rRNA gene sequencing. WS2 NMs at 100 mg/kg significantly decreased soil microbial diversity, as indicated by decreased Shannon index. In addition, 100 mg/kg WS2 shifted the soil microbial profile, the relative abundance of the phylum Acidobacteriota decreased, and Actinobacteriota increased. Taken together, the soil microbial community's diversity and composition have been altered upon exposure to 100 mg/kg WS2 NMs. The results of this study provide some basic information regarding the environmental behavior and phytotoxicity of WS2 NMs, which is valuable for safe use of WS2 NMs.