金属氧化物纳米颗粒的土壤微生物群落促进效应及其作用机制研究

With the development of nanotechnology, metal oxide nanoparticles (MONPs) are inevitably released into soil and impose impact on soil microbial community and their ecological function. The promoting effects of MONPs on soil microbes, which is the important component of soil ecosystem, has attracted increasing attention. In this project, the optimum promoting conditions (size and dose) of two typical MONPs (CuO and γ-Fe2O3 NPs) on agricultural soil bacterial and fungal community will be investigated using laboratory microcosm cultivation. The transformation characteristics of MONPs in soil will be studied using chemical extraction methods and synchrotron radiation X-ray absorption spectroscopy to assess the dynamic change of MONPs bioavailability. The effects of MONPs on soil physiochemical properties will also be measured. The response of soil bacterial and fungal community abundance, composition and function to MONPs will be explored using MiSeq high-throughput sequencing and quantitative PCR. Based on sequencing data, the community assembly mechanism and driven force will be revealed by using phylogenetic structure and null model analysis. This project will provide theoretical basis for the promoting effects of MONPs on soil microbes.

随着纳米科技的发展，纳米颗粒（nanoparticles，NPs）会不可避免地进入土壤，并对土壤微生物群落及其生态功能产生影响。近年来，金属氧化物纳米颗粒（MONPs）的土壤微生物促进效应越来越受到关注，而其作用机制还尚不清楚。本项目拟以农田土壤微生物群落为研究对象，在实验室微宇宙培养条件下，确定CuO和γ-Fe2O3 NPs促进土壤微生物活性和生物量的最优MONPs粒径和施用量。通过化学提取方法和同步辐射技术，明确MONPs在土壤中的生物有效性变化规律及其对土壤理化性质的影响；以高通量测序和qPCR为主要手段，探究土壤微生物群落演替规律（丰度、组成和功能），并在生态构建理论的指导下，结合群落系统发育结构和零模型分析方法，揭示MONPs土壤微生物群落促进作用的群落构建机制和关键驱动因子。该结果能够为深入地理解MONPs土壤微生物群落的促进机制提供理论依据。

近年来，随着金属氧化物纳米颗粒（NPs）的大量生产和使用，使其不可避免地进入土壤，并对土壤微生物群落及其生态功能产生影响，而其作用机制还尚不清楚。本项目以γ-Fe2O3 NPs（Fe NPs）为研究对象，阐明了Fe NPs在土壤中的转化过程及其对土壤理化性质的影响，明确了Fe NPs对土壤微生物群落组成、结构和功能的影响，揭示了Fe NPs影响下土壤微生物群落构建机制和驱动因子。得到以下主要结果：（1）随着Fe NPs的施用浓度增加，土壤中有效铁含量和电导率值升高，土壤pH值降低。（2）低浓度的Fe NPs对土壤细菌群落无显著影响，而较高浓度（50 mg/kg）的Fe NPs抑制了土壤脲酶和磷酸酶的活性，降低了土壤细菌群落的丰富度和多样性，改变了细菌群落组成和结构。（3）随着Fe NPs的施用浓度增加，细菌群落的NTI值呈现下降趋势，表明Fe NPs导致细菌群落谱系结构相对发散，竞争排斥为群落构建的主要机制。土壤有效铁和电导率变化是细菌群落构建的主要驱动因子。项目研究成果可用于支撑Fe NPs的环境生态安全评估，并为调控Fe NPs的土壤微生物效应提供了新的思路和数据支撑。