铜-四环素络合对水生植物根系吸附和转移四环素的影响与机理

The remediation of antibiotics under the combined pollution of heavy metals in wastewater from animal-producing establishments has attracted increasing concern on the field of pollution control. As a kind of economic and effective pollution control material, the aquatic plants were widely used on the operation of bioremediation with the roots as an important factor contributes to the removal of pollutants. It is an urgent scientific issue that the remediation mechanism of antibiotic, especially, the adsorption characteristics and migration mechanism of antibiotics by plant roots under the influence of heavy metals are very limited. In this project, batch experiments will be carried out to elucidate the kinetics and thermodynamics of adsorption characteristics of the typical veterinary antibiotics-tetracycline with the complexation of copper (Cu) on the roots of water hyacinth (Eichhornia crassipes). Scanning electron microscopy and infrared spectroscopy technology were employed to elucidate the micro-morphology and chemical functional groups of root surface, and the combination of different Cu-tetracycline complexation with root surface, which will help to clarify the adsorption mechanism of tetracycline on plant roots. The migration pathway of tetracycline from the root surface to the root tissues, and its distribution on root tissues were investigated in a self-developed culture apparatus by using Laser Confocal Scanning Microscopy technique. It is of critical scientific significance that the research findings will provide scientific basis and support for the phytoremediation of antibiotics pollution in livestock and poultry wastewater.

水生植物是一类应用前景良好的生态修复材料，其根系在污染水体治理中的作用及机理是环境污染治理技术与生态修复理论研究中的热点。抗生素、重金属作为我国养殖废水中并存的典型污染物，二者络合反应对其在植物根系的吸附和迁移的影响与作用机制，是当前迫切需要关注的科学问题。本项目以凤眼莲为材料、四环素为对象，采用批吸附平衡法，研究铜络合对凤眼莲根系吸附、转移四环素的影响，分析络合态与非络合态四环素在凤眼莲根系表面吸附动力学、热力学状态参量的变化特征；利用自主研发的水生植物培养装置，结合激光共聚焦扫描荧光显微镜观测技术，探讨铜络合/非络合态四环素由根表向根组织内部的迁移途径及其赋存特征，并借助扫描电子显微镜和傅里叶变换红外光谱技术，阐明铜络合对四环素在凤眼莲根系表面吸附与根内组织迁移的影响，揭示其作用机制。项目研究成果将为我国养殖废水中抗生素与重金属复合污染水体的生态修复与污染控制提供科学依据。

随着畜禽养殖业向着集约化发展，养殖场废水中重金属和抗生素协同污染日益严重，为此，本研究以漂浮植物凤眼莲为修复材料，养殖废水典型污染物-铜( Cu )和四环素( TC )抗生素为研究对象，探讨凤眼莲对重金属和抗生素复合污染的去除和积累效应。.首先考察了TC和Cu2+的络合情况，研究发现当TC与Cu2+发生络合后，紫外吸收光谱发生红移，用连续变化法和摩尔比法测得，TC和Cu2+的络合比为1:1和1:2；结合红外光谱可知，TC主要通过C-3上的羰基以及二甲氨基与Cu2+发生络合。通过批吸附平衡实验，考察Cu2+共存条件下TC在杀青凤眼莲根系上的吸附动力学和吸附热力学，并结合傅里叶红外光谱（FTIR）、X-射线光电子能谱（XPS）和基团屏蔽技术分析Cu2+对TC在凤眼莲根系吸附特征的影响及机理。结果表明：凤眼莲根系对TC吸附过程分别符合准二级动力学和Freundlich等温吸附模型，且吸附过程中物理作用力和化学作用力同时存在。随着体系中共存Cu2+浓度的增加，根系对TC的吸附量也逐渐增大。根系表面羧基、氨基经化学屏蔽后，对TC的吸附量均降低了20%~30%；结合FTIR和XPS技术确定Cu2+通过与根系表面的活性官能团（羧基和氨基）发生相互作用，在根系与TC之间形成架桥，从而促进了根系对TC的吸附。.种植凤眼莲能加速污染水体中TC的消减，10 d后所有处理中TC的消减速率均在94.9%以上。凤眼莲去除TC的主要方式是根部吸收/吸附，极少部分由根部向地上部分迁移。Cu2+的共存能显著增加TC在新鲜/杀青凤眼莲根部的富集。但杀青根系和新鲜植株对TC的去除机理存在一定差别。相较于新鲜的凤眼莲根系而言，杀青后的凤眼莲根系去除TC的效率有所降低。随着时间的推移，新鲜植株凤眼莲根部富集的TC会逐渐减少，而杀青根系吸附的TC会逐渐增加。