Bai Leilei, Cao Chicheng, Wang Chunliu, Wang Changhui, Zhang Hui, Jiang Helong
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; Graduate University of Chinese Academy of Sciences, China.
Key Laboratory of Environmental Medicine Engineering of Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, China.
Environ Pollut. 2017 Nov;230:87-95. doi: 10.1016/j.envpol.2017.06.032. Epub 2017 Jun 22.
Phytoplankton-derived dissolved organic matter (PDOM) and macrophyte-derived dissolved organic matter (MDOM) exist ubiquitously in eutrophic freshwater lakes. To understand the heterogeneous roles of individual fluorescent DOM components in the adsorption of antibiotics onto sediment minerals, the adsorptive fractionation of DOM on goethite (α-FeOOH) and its interaction with sulfamethazine (SMT) were investigated using fluorescence excitation-emission matrix combined with parallel factor analysis (EEM-PARAFAC). The affinity sequence for goethite of the 4 fluorescent PARAFAC components followed the order of: tryptophan- > tyrosine- > long emission wavelength (LEW) humic- > and short emission wavelength (SEW) humic-like component. This sequence indicated the preferential adsorption of protein-like substances. Meanwhile, tyrosine-like components can strongly form complexes with SMT with a large binding constant, followed by tryptophan- and SEW humic-like components. However, LEW humic-like component did not effectively react with SMT. The main mechanism of fluorescence quenching between DOM and SMT was static quenching. The result indicated that protein-like substances in DOM were favorable to SMT adsorption by acting as a bridge to form complexes with both goethite surface and SMT molecules, whereas humic-like substances played secondary roles in the DOM-goethite-SMT ternary system. Due to its higher content of protein-like substances, PDOM improved the SMT adsorption on goethite more than MDOM. Therefore, the abundant DOM released from phytoplankton and macrophytes affected the transport of antibiotics to sediments and might eventually change their bioavailability and toxicity to organisms.
浮游植物衍生的溶解有机物（PDOM）和大型植物衍生的溶解有机物（MDOM）普遍存在于富营养化淡水湖泊中。为了解单个荧光溶解有机物（DOM）组分在抗生素吸附到沉积物矿物上的不同作用，采用荧光激发-发射矩阵结合平行因子分析（EEM-PARAFAC）研究了DOM在针铁矿（α-FeOOH）上的吸附分级及其与磺胺二甲嘧啶（SMT）的相互作用。4种荧光PARAFAC组分对针铁矿的亲和顺序为：色氨酸->酪氨酸->长发射波长（LEW）腐殖质->短发射波长（SEW）类腐殖质组分。该顺序表明类蛋白质物质优先吸附。同时，类酪氨酸组分能与SMT强烈形成络合物，结合常数较大，其次是色氨酸和SEW类腐殖质组分。然而，LEW类腐殖质组分与SMT没有有效反应。DOM和SMT之间荧光猝灭的主要机制是静态猝灭。结果表明，DOM中的类蛋白质物质有利于SMT的吸附，它作为桥梁与针铁矿表面和SMT分子形成络合物，而类腐殖质物质在DOM-针铁矿-SMT三元体系中起次要作用。由于其类蛋白质物质含量较高，PDOM比MDOM更能促进SMT在针铁矿上的吸附。因此，浮游植物和大型植物释放的大量DOM影响抗生素向沉积物的迁移，并可能最终改变其对生物的生物有效性和毒性。
