土壤蚓触圈生境中合成孕激素吸附迁移与生物降解的强化耦合机制

The widely used synthetic progestins are considered as the emerging environmental steroid hormone contaminants. The residual progestins in soil caused by applying livestock wastes in the farmland has led to frequent occurrence of endocrine disruption emergencies, resulting in serious ecological and human health risks. First, this project will explore the adsorption-desorption, abiotic transformation, and transport behaviors of synthetic progestins based on static sorption and fluid transport systems. CXTFIT model software will be used as well to obtain the breakthrough curves during transport. Then, we will explore the aerobic biodegradation kinetics of progestins, and identify the major degradation products and related biological activities. The efficient degrading strains for progestins and related active intermediates will be screened out, and will be used to elucidate the key enzymes involved in the aerobic degradation process and the gene protein network of biological metabolism by using the RNA-seq method. Finally, microcosm will be built to explore the enhanced coupling and biologic cooperative mechanisms of progestin sorption and degradation in soil-drilosphere habitat. The results of this project will provide theoretical support for accurately predicting ecological risks caused by progestins, clarifying the ecological self-purification processes driven by soil animals and microorganisms, and for establishing green pollution prevention and control measures for emerging organic pollutants.

合成孕激素是广泛使用的新型环境类固醇激素污染物，养殖废弃物农用导致的土壤孕激素残留引起内分泌干扰现象频繁发生，造成严重的生态环境与人体健康风险。本项目基于静态吸附和流态迁移体系统，利用CXTFIT模型软件绘制迁移穿透曲线，揭示合成孕激素在土-水体系的吸附-解吸，非生物转化和迁移过程与影响机制。研究孕激素的好氧生物降解动力学过程，鉴别主要降解产物及其活性。筛选孕激素及其高内分泌干扰活性中间产物高效降解菌株，利用RNA-seq法阐明孕激素好氧降解过程的关键酶类和生物代谢的基因蛋白网络。利用土壤污染控制实验研究蚯蚓介导的土壤蚓触圈生境中的孕激素吸附与降解的强化耦合作用与生物协同驱动机制。将为准确预测环境孕激素生态风险、明确生物驱动的土壤生态自净功能、建立新型有机污染物的绿色防控措施提供理论支撑。

畜禽粪便作为有机肥施入农田是实现粪污资源化的重要途径。施肥过程中孕激素会进入土壤，并通过降雨进入地表径流，对周边水生生物产生潜在的内分泌干扰效应。因此，本项目系统研究了合成孕激素在农田水土体系中的吸附解吸机制，非生物转化、生物转化过程机制、迁移转化耦合机制以及土壤蚓触圈生境中合成孕激素转化降解的调控作用。结果表明，孕激素的辛醇-水分配系数（logKow）和它们的吸附系数（logKd）呈显著正相关，而且孕激素的Kd值和土壤有机质含量、孔体积显著正相关，证实了疏水性分配作用和孔填充作用是孕激素的主要吸附机制。通过加入氢键破坏剂，发现孕激素的吸附能力显著下降，说明氢键也是吸附机制。研究还探索了合成孕激素在典型土壤矿物发生了非生物转化作用。pH、温度、矿物质量和粒径分布均会影响其转化速率。通过飞行时间质谱分析发现合成孕激素主要发生水解、羟基化等作用。研究进一步探索了污染物在土壤典型微生物中的转化过程。结果表明，pH、碳源等因子均显著影响微生物转化过程。项目发现典型合成孕激素在土柱迁移过程中会发生生物转化作用。而且，生物转化动力学显著影响母物质及其转化产物的迁移潜势。结果发现，0-22 PV阶段，孕激素及其产物的滞留因子与其色谱保留时间显著负相关，而在22-108 PV阶段为显著性正相关，表明孕激素及其产物在同步迁移转化过程中，其迁移潜势受转化动力学影响。最后，项目研究了蚓触圈生境中典型有机污染物的消减过程。结果表明，蚓触圈可显著促进土壤中有机污染物的微生物降解，另外，蚓触圈还可以改变污染物降解的主要路径。本研究将为农田土壤中有机污染物的去除提供基础。