Environmental implications of MoS2 nanosheets on rice and associated soil microbial communities

Molybdenum disulfide (MoS2) is a transition metal dichalcogenides (TMDCs) material that is seeing rapidly increasing use. The wide range of applications will result in significant environmental release. Here, the impact of MoS2 nano-sheets on rice and associated soil microbial communities was evaluated. Rice plants were grown for 4 weeks in a natural paddy soil amended with either 1T or 2H phase MoS2 nanosheets at 10 and 100 mg kg(-1). The 1T MoS2 nanosheets have a significantly greater dissolution rate (58.9%) compared to 2H MoS2 (4.4%), indicating the instability of 1T MoS2 in environment. High dissolution rate resulted in a high Mo bioaccumulation in rice leaves (272 and 189 mg kg-1 under 1T and 2H exposure at 100 mg kg(-1)). However, this did not induce overt phytotoxicity, as indicated by a range of phenotypic or biochemical based determine endpoints, e.g., biomass, photosynthetic pigments, and malondialdehyde (MDA) content. Additionally, rice P uptake was significantly increased upon exposure to 1T and 2H MoS2 (10 mg kg(-1)). Gas chromatography-mass spectrometry (GC-MS) reveals that both phases of MoS2 in soil sys-tematically enhanced the carbon and nitrogen related metabolic pathways in exposed plants. Soil 16S rRNA gene sequencing data show that soil microbial community structure was unchanged upon MoS2 exposure. However, both phases of MoS2 remarkably increased the relative abundance of N-2-fixation cyanobacteria, and 2H MoS2 exposure increased a plant growth-promoting rhizobacteria-Bacillus. Overall, our results suggest that MoS2 nanosheets at tested doses did not exert negative impacts on rice plant and the associated soil microbial community.

Automated summary

This study evaluated the impact of MoS2 nanosheets on rice plants and soil microbial communities. The results showed that MoS2 nanosheets did not have negative effects on rice plants and soil microbial communities at the tested doses.