氧化铜纳米颗粒对稻田土壤及微生物生态的作用机制

发布时间：2018-07-04 08:52

  本文选题：金属纳米颗粒 + 氧化钢纳米颗粒(CuO)　； 参考：《浙江大学》2016年博士论文

【摘要】：随着纳米科技的不断发展,大量金属纳米颗粒在生产运输、使用及处置过程中不可避免会进入土壤,对生态系统及人类健康造成威胁。稻田土壤作为我国典型的湿地农田生态系统,土壤质量直接关系到水稻产量及环境健康。因此,为科学评估金属纳米颗粒的农业生态及健康风险,推动纳米科技健康可持续发展,本论文以典型金属纳米颗粒CuO NPs作为研究对象,模拟CuO NPs进入稻田土壤的环境条件,考察CuO NPs在淹水落干过程中的形态转化及对土壤性质及物质组成的影响,着重探讨CuO NPs对土壤微生物的毒性作用机理及对微生物群落结构和生态功能的影响机制。主要研究结果如下：(1)阐明CuO NPs在稻田土壤中的形态转化规律,证明CuO NPs输入会影响稻田土壤理化性质及物质组成的变化。研究发现CuO NPs进入土壤中可迅速发生转变,并逐渐向更稳定的络合态或沉淀态发展,且转化规律与有机质含量等土壤性质相关。CuO NPs对稻田土壤性质造成了不同程度的影响：其中,CuO NPs的金属特征会影响土壤pH、Eh、Ec等环境因子的变化,而土壤吸附能力和阳离子交换能力等化学性质未受影响；包括矿物质、有机质和微生物在内的土壤固相组分均受到CuO NPs的显著影响,且纳米颗粒对微生物的影响在土壤其他组分的变化中起了关键作用。土壤有机质可以在一定程度上缓解CuONPs对土壤性质的作用效应。(2)弄清TiO2 NPs和CuO NPs分别以颗粒性质和重金属特性对微生物产生毒性的作用机理。通过对比研究发现,CuO NPs和TiO2 NPs均会对稻田土壤微生物及其群落产生一定的扰动,且CuO NPs的作用强于TiO2 NPS。其中Ti02NPs对土壤酶活的影响较为复杂,对土壤微生物量及群落组成的影响较小；而CuO NPs的施加则显著降低了土壤微生物量、酶活、微生物群落的组成及生物多样性。通过Pearson分析纳米颗粒的有效形态与微生物作用的相关性发现,TiO2 NPs主要通过其颗粒本身的性质影响土壤微生物,而淹水稻田土壤中的CuO NPs由于具有高度的溶解性和重金属生物有效性,从而对土壤微生物产生了较大的毒害作用。此外,CuO NPs还可通过改变土壤营养元素的可利用能力间接影响土壤微生物的生存和发展。(3)揭示了CuO NPs作用下水稻根际微生物群落的演变规律,发现CuONPs颗粒及重金属特性的微生物差异响应及其对微生物生态系统稳定性的影响。利用Miseq高通量测序研究发现,CuO NPs的不同特性对不同菌属造成了相反的影响：由于CuO NPs的金属毒害作用,以Chloroflexi为代表的大部分根际细菌的生长受到了CuO NPs的显著抑制,相对丰度降低,其中参与氮循环的微生物对CuO NPs高度敏感；而包括纤维素降解菌、铁还原菌和硫还原菌等部分细菌由于CuO NPs颗粒特性的影响,逐渐成为优势菌属。CuO NPs加剧了水稻根际土壤细菌群落多样性的消减和群落的演替,严重影响了根际土壤微生物生态系统的稳定性。同时,水稻根际环境会影响CuO NPs对根际微生物群落的调控作用。(4)明确了CuO NPs调控水稻根际特殊微生物功能的耦合作用,从而影响了稻田土壤物质循环。利用Q-PCR技术研究发现CuO NPs可以利用特殊的颗粒特性增加微生物细胞与纤维素物质之间的接触和附着,从而促进纤维素降解菌的活性和生长。大量的可溶性有机碳又可进一步为产甲烷菌、铁还原菌等功能微生物提供丰富的碳源,同时,CuO NPs还可利用其特殊的纳米颗粒特性直接参与微生物间的电子传递,从而促进微生物的产甲烷及铁还原过程。而参与氮循环的功能微生物对CuO NPs敏感,但响应不一,并最终未影响土壤N20的排放。
[Abstract]:With the continuous development of nanotechnology, a large number of metal nanoparticles inevitably enter the soil in the process of transportation, use and disposal, which threaten the ecosystem and human health. The paddy soil is a Typical Wetland Farmland Ecosystem in China. The soil quality is directly related to the rice yield and environmental health. Therefore, it is the science of science. To assess the agro ecological and health risks of metal nanoparticles and promote the healthy and sustainable development of nanotechnology, this paper uses the typical metal nanoparticles CuO NPs as the research object to simulate the environmental conditions of CuO NPs into the paddy soil, and investigate the transformation of CuO NPs in the process of flooding and the effects on the soil properties and the composition of the soil. The toxic mechanism of CuO NPs on soil microorganism and the mechanism of influence on microbial community structure and ecological function were discussed. The main results were as follows: (1) the morphological transformation of CuO NPs in paddy soil was clarified, and it was proved that CuO NPs input would affect the changes of physical and chemical properties and material composition of paddy soil. The study found that CuO NPs was entered. It can change rapidly into the soil and gradually develop to a more stable complex or precipitation state, and the transformation law and the soil properties related to organic matter content such as the content of.CuO NPs have different effects on the soil properties of the paddy field. Among them, the metal characteristics of CuO NPs will affect the changes of environmental factors such as pH, Eh, Ec and so on, and the soil adsorption energy The chemical properties such as force and cation exchange capacity have not been affected; the soil solid components, including minerals, organic matter and microorganism, are significantly affected by CuO NPs, and the effect of nanoparticles on microbes plays a key role in the change of other soil components. Soil organic matter can mitigate CuONPs to soil to a certain extent. The effect of soil properties. (2) to clarify the mechanism of TiO2 NPs and CuO NPs to produce toxicity to microbes by particle and heavy metals respectively. Through comparative study, it is found that both CuO NPs and TiO2 NPs produce certain disturbance to the soil microorganism and its community in the paddy field, and the effect of CuO NPs is stronger than that of TiO2 NPS.. The effect of living is more complex, and it has little effect on soil microbial biomass and community composition, while the application of CuO NPs significantly reduces soil microbial biomass, enzyme activity, microbial community composition and biological diversity. The correlation between the effective morphology of nanoparticles and the effect of microbes by Pearson analysis shows that TiO2 NPs is mainly through its particles. Its own nature affects soil microbes, and the CuO NPs in the flooded paddy soil has a great toxicity to soil microbes because of its high solubility and bioavailability of heavy metals. In addition, CuO NPs can also indirectly influence the survival and development of soil microbes by changing the available energy of soil nutrient elements. 3) revealed the evolution of the rhizosphere microbial community of CuO NPs, found the response of CuONPs particles and heavy metal characteristics and their effects on the stability of the microbial ecosystem. Using Miseq high throughput sequencing, it was found that the different characteristics of CuO NPs had the opposite effect on different bacteria genera: due to CuO NPs The growth of most rhizosphere bacteria, represented by Chloroflexi, was significantly inhibited by CuO NPs, and the relative abundance was reduced. The microorganisms involved in the nitrogen cycle were highly sensitive to CuO NPs, while the cellulose degrading bacteria, iron reducing bacteria and sulfur reducing bacteria were gradually formed by the effect of CuO NPs particle properties. .CuO NPs intensifies the decline of bacterial community diversity in rhizosphere soil and succession of community, which seriously affects the stability of microbial ecosystem in rhizosphere soil. Meanwhile, the rice rhizosphere environment affects the regulation of CuO NPs on the rhizosphere microbial community. (4) it is clear that CuO NPs regulates the special microbial function of rice rhizosphere. The coupling effect affects the soil material circulation in the paddy field. Using the Q-PCR technology, it is found that CuO NPs can increase the contact and attachment between microbial cells and cellulose materials by special particle properties, thus promoting the activity and growth of cellulose degrading bacteria. The functional microorganisms such as reducing bacteria provide a rich carbon source. At the same time, CuO NPs can also use its special nano particle properties to directly participate in the electron transfer between microorganisms, thus promoting the microbial methane production and iron reduction process. The functional microorganism involved in nitrogen cycle is sensitive to CuO NPs, but the response is not one, and it does not affect the N20 row of soil in the soil. Put it.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X53;X172
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本文编号：2095518