酸化加剧下生物炭对红壤中磺胺类抗生素生物可利用性的影响及其机制

The environmental effects of emerging contaminants antibiotics as well as biochar have become a hot research topic in the world. However, the effect of biochar on the bioavailability of organic pollutants and its mechanism in the process of improving soil carbon sequestration under acidification is not clear. Therefore, emerging contaminants sulfonamides (SAs) are chosen as representative pollutants. And different types of biochar(such as rice straw, feces, etc.) and Jiangxi Red Soil Farmland are studied. And Eisenia foetida is using as the Model Organism. The sorption, degradation and bioaccumulation of SAs in biochar amended red soil are studied under the condition of acidification by batch equilibrium method as well as the leaching kinetics, degradation kinetics and accumulation kinetics. The influence of biochar properties, carbon content and SAs forms on the sorption and bioavailability of SAs in red soil are explored. On this basis, the sorption and immobilization mechanisms of biochar to SAs on different acidity red soil are clarified by means of SEM, FTIR, BET, XRD and other analysis methods. And then, the effect mechanism of biochar on the bioavailability of SAs on acidification soil are revealed, which provides scientific basis for the scientific assessment of the environmental risks of antibiotics in the red soil during the course of the change of soil carbon sequestration.

新型污染物抗生素及生物炭的环境效应已成为国际研究热点。但酸化加剧下生物炭在改土固炭过程中如何影响土壤有机污染物的生物可利用性，其影响机制是什么？并不清楚。为此，本项目以新型环境污染物磺胺类抗生素（SAs）为例，选择不同类型的生物炭（如稻秆类、粪便类等）和江西农田红壤为研究对象，以赤子爱胜蚓为模式生物。采用批量平衡法并结合淋溶动力学、降解动力学及富集动力学等方法，研究酸化加剧下生物炭对红壤中SAs吸附、降解和生物累积行为，探明生物炭性质、含量及SAs存在形态等对红壤中SAs吸附固持及生物可利用性的影响规律。在此基础上，通过SEM、FTIR、BET、XRD等分析手段，阐明生物炭对不同酸化红壤吸附固持SAs的影响机制，揭示酸化加剧下生物炭对红壤中生物可利用性的影响机制，为科学评估生物炭在改土固炭过程中对红壤环境中抗生素的环境风险提供科学依据。

本项目根据江西农田红壤生物炭的施用情况及当前农田土壤中突显的磺胺类抗生素污染，深入、系统研究了酸化加剧下生物炭对红壤中SAs吸附、降解和生物累积行为及作用机制。研究了酸化加剧下生物炭对红壤中SAs吸附固持行为，探明了不同酸化条件磺胺类抗生素在生物炭及红壤上吸附固持的影响及微观作用机制，生物炭对磺胺类抗生素吸附机理包括：疏水分配作用、静电引力或者氢键作用、空洞填充和阳离子-π及π-π电子供受体(EDA)作用，主要作用机理受pH的严重影响；探明了酸化加剧下，生物炭对红壤中SAs微生物降解行为及在蚯蚓体内的富集行为的影响规律，阐明生物炭的吸附固持和营养刺激双重作用对SAs的微生物降解及生物吸收利用性影响机制，生物炭可有效阻控污染红壤中抗生素的迁移，对蚯蚓富集有一定的抑制作用，降低了抗生素污染风险；揭示了酸化加剧下生物炭对红壤中生物可利用性的影响机制，生物炭的吸附固持作用抑制了SAs的生物可利用性，生物炭营养成分，刺激土壤微生物生长，进而提升了SAs的微生物降解。研究结果可为科学评估生物炭在改土固炭过程中对红壤环境中抗生素的环境风险提供科学依据。