土壤中线虫对纳米零价铁和五氯酚复合暴露的响应机制与调控原理

With the increasing application of nano-zero valent iron (nZVI) in the remediation of organochlorine (OCs) polluted soils and groundwater, it is urgent to explore the combined biological effect of nZVI and OCs. We have preliminarily found that the combined effect of nZVI and pentachlorophenol (PCP) on nematodes (C. elegans) was antagonistic at certain concentrations; moreover, nZVI and nematodes have the potential to synergistically remove PCP from soil. Based on this preliminary research, this project was aimed to illuminate molecular mechanisms and influencing factors of nematodes responding to the nZVI-PCP co-exposure in soil, and to establish and improve the interplay system of nZVI and nematodes to synergistically remove PCP within the soil. Single- and co-exposure experiments will be conducted, and technologies such as synchrotron radiation, GC/LC-MS, transcriptomics, metabolomics will be applied to reveal: the transformation of nZVI and PCP in soil and nematodes; effects of nZVI-PCP co-exposure on soil properties; and mechanisms of gene and metabolic responses in nematodes upon the exposures. The effect and mechanism of nZVI property and concentration, environmental parameters, and biological factors on the synergistically removal of PCP by nZVI-nematodes will be specifically addressed. By revealing the dominating influencing factors, the removal efficiency of PCP will be improved on the basis of biological security. This project is believed to expand the research direction of the co-effect of NMs and pollutants, and provide new technology for the control of soil pollution.

纳米零价铁(nZVI)在土壤/地下水有机氯(OCs)污染修复中的应用日益增加，亟需探明nZVI与OCs的复合生物效应。申请人前期研究发现，一定浓度下nZVI和五氯酚(PCP)对线虫的复合效应表现为拮抗，并且nZVI与线虫存在协同去除土壤PCP的潜力。本项目旨在阐明土壤中线虫对nZVI和PCP复合暴露响应机制与影响因素的基础上，构建和优化nZVI-线虫互作体系以协同去除土壤中PCP。将设置单一/复合暴露实验，运用同步辐射、液/气-质联用、转录/代谢组学等技术，系统研究nZVI和PCP在土壤和线虫中的形态转化及对土壤性质的影响，深入剖析线虫基因和代谢水平的响应机制，阐明nZVI性质与浓度、环境条件、生物累积与代谢等因素对nZVI-线虫协同去除PCP的作用机制，明确主控因素，在保障生物安全的基础上提高对PCP的去除效率。研究结果将拓展纳米材料与污染物复合效应研究的方向，为治理土壤污染提供新技术。

当前对纳米材料与污染物复合生物效应的研究普遍立足于评估纳米材料的环境风险。本项目在阐明土壤中线虫对纳米零价铁（nZVI）和五氯酚（PCP）复合暴露响应机制与影响因素的基础上，构建和优化nZVI-线虫互作体系以协同去除土壤中PCP。首先比较了不同粒径、表面改性铁基微纳材料对PCP污染土壤中线虫存活率的影响，发现了小粒径nZVI可显著降低PCP对线虫的毒性效应，明确了线虫促降解作用与nZVI-PCP拮抗毒性的耦合关系；基于转录-代谢多组学关联分析，筛选到胶原蛋白、谷胱甘肽、半胱氨酸等三种显著响应复合暴露的生物分子作为候选促降解化合物，利用荧光探针等分子定位技术证实了促降解分子在NMs-生物界面的空间分布；进一步通过水中模拟实验，从界面相互作用的角度揭示了表皮胶原蛋白螯合nZVI颗粒促进其在土壤中迁移，而谷胱甘肽和半胱氨酸通过溶解钝化层活化nZVI的差异化促降解机制；最后，构建了nZVI、半胱氨酸、线虫等组分对土壤PCP降解性能的响应曲面数学模型，优化了半胱氨酸强化的nZVI-线虫协同修复体系，实现了3天内高效去除土壤中PCP，在提升2.1倍PCP去除效率的同时将nZVI用量降低至单一nZVI修复技术的48.5%。研究成果不仅可为评估纳米材料的土壤环境风险提供科学依据，还为治理土壤有机污染提供了新思路。