Combined effects of microplastics and Pb on soil-tobacco systems revealed by soil microbiomics and metabolomics
摘要
Co-contamination risks of microplastics(MPs)and toxic heavy metals such as lead(Pb)to soil-plant systems remain poorly understood.Therefore,we conducted a two-month greenhouse pot experiment to explore the responses of soil-tobacco systems to polyethylene(PE),polyvinyl chloride(PVC),and polylactic acid(PLA)MPs(0,0.2％,and 2％,weight/weight)under varying Pb levels(0,400,and 800 mg kg-1).Generally,the combined exposure to MPs and Pb produced higher inhibition than single treatments,with the lowest shoot biomass observed under co-exposure to 2％PLA and 400 mg kg-1 Pb.Microplastics increased soil available Pb concentrations at 400 mg kg-1 Pb,but decreased them at 800 mg kg-1 Pb,and generally reduced root and leaf Pb concentrations as well as leaf Mn,Fe,and Cu concentrations.Overall,2％PLA caused more profound alterations in soil properties.Co-exposure to 2％PLA and 400 mg kg-1 Pb caused the largest reductions in soil bacterial α-diversity.Both Pb and MPs(particularly 2％PLA)changed soil bacterial community composition,with significant enrichments in Actinobacteriota(phylum)and Streptomyces(genus).Soil metabolomics analysis further revealed that MPs and Pb disrupted several metabolic pathways,such as secondary metabolite synthesis,amino acid metabolism,and lipid metabolism.In conclusion,co-existing MPs can interact with Pb to disrupt tobacco growth,Pb accumulation,soil microbial communities,and soil metabolites.For the first time,our study evaluated the co-contamination risks of MPs and Pb in soil-tobacco systems,offering new insights for the management and remediation of soils contaminated with these contaminants.
