典型叶菜对磺胺类抗生素的根际吸收机制研究

As the largest antibiotics producer and user in the world, China consumed about 162 000 tons of antibiotics in 2013. Several pathways (e.g., application of animal waste as fertilizer) can lead to soil contamination, in which antibiotics exhibit rather high concentration, various types and widespread distribution. Uptake of antibiotics by vegetables and grains results in passive exposure of human to antibiotics via food chain. Previous studies indicated that the composition and properties of soil can significantly influence the ionized speciation, sorption and transformation of antibiotics. In China, soil types are abundant and diverse, and soil constitutes and properties are very different.The plant uptake of antibiotics in variant soils is expected to follow different rules. To date, the effect of soil constitutes and properties on the plant uptake of antibiotics has not been well examined yet. The transferring of antibiotics from soil surface to root surface is a dynamic process, which is susceptible to various factors, e.g., sorption, degradation, uptake and supplement. During this process, rhizosphere has been proved to play a crucial role in the uptake of nutrition and pollutants. In this study, a number of regionally typical soils will be collected, and experiments including sorption, degradation, water culture, soil culture and rhizobox culture will be conducted. Additionally, some novel techniques, such as rhizosphere soil solution sampler, diffusive gradients in thin-films (DGT), isotopic tracing, and high resolution mass spectrum, will be employed to reveal the mechanisms of rhizosphere uptake of ionizable sulfonamide antibiotics by several leafy vegetables, and to provide scientific evidence for the evaluation of human exposure to antibiotics via food consumption.

我国是抗生素生产和使用第一大国，2013年使用量超过16.2万吨。施用畜禽粪便等途径导致土壤中抗生素污染水平高、种类多、分布广。抗生素被蔬菜和粮食等作物吸收，会通过食物链引起人体的被动暴露。研究表明，土壤的组成和性质对抗生素的电离形态、吸附分配、降解转化都有重要影响。我国土壤类型多样，土壤组成和性质差异显著，抗生素在不同土壤中会存在不同的吸收规律。但迄今，土壤组成和性质对植物吸收抗生素的影响尚缺少系统的研究。抗生素从土表迁移到根表，是吸附、降解、吸收和补给等多因素影响的动态过程。其中，根际过程对于植物吸收发挥关键的作用。本研究拟采集一些具有代表性的土壤，开展吸附、降解、水培、土培、根箱等实验，采用根际土壤溶液取样器、梯度扩散薄膜、同位素示踪和高分辨质谱分析等技术，以揭示典型叶菜对可电离的磺胺类抗生素的根际吸收机制，为评价抗生素通过食物摄取对人体的暴露风险提供科学依据。

我国是抗生素生产和使用第一大国。农业生产中施用畜禽粪便等途径导致土壤中存在抗生素污染。抗生素被蔬菜和粮食等作物吸收，会通过食物链引起人体的被动暴露。本项目采用根际土壤溶液取样器和高分辨质谱分析等技术，考察了不同抗生素在水培和土壤培养条件下的吸收和转运规律，揭示了一些典型抗生素的植物吸收机制；考察了磺胺嘧啶、克拉霉素等的植物代谢行为，表征了代谢产物、推测了代谢路径；考察了抗生素对水稻根际微生物种群的影响。本项目的研究成果加深了对土壤中抗生素植物吸收机制的认识，可以为评价抗生素通过食物摄取对人体的暴露风险提供科学依据。