Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, School of Environmental Science and Engineering, Hainan University, Haikou 570228, China.
Department of Civil and Environmental Engineering, The Faculty of Engineering, The University of Auckland, Pribate Bag 92019, Auckland 1142, New Zealand.
Sci Total Environ. 2024 Oct 20;948:174785. doi: 10.1016/j.scitotenv.2024.174785. Epub 2024 Jul 14.
The increasing presence of oxytetracycline (OTC) in agricultural soils has raised global environmental concerns. We investigated the environmental behavior and fate of OTC in two types of tropical agricultural soils, focusing on the impact of dissolved organic matter (DOM) from biogas slurry. Techniques such as three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM), Fourier Transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and Ultraviolet-visible spectrophotometer (UV-vis) were used to explore the adsorption mechanisms. Our findings revealed that biogas slurry-derived DOM decreased the OTC adsorption on soils and extended the time to reach adsorption equilibrium. Specifically, the equilibrium adsorption of OTC by the two soils decreased by 19.41 and 15.32 %, respectively. These adsorption processes were effectively modelled by Elovich, intraparticle diffusion, linear, and Freundlich thermodynamic models. Thermodynamic parameters suggested that OTC adsorption onto soils was spontaneous and endothermic, with competitive interactions between biogas slurry-derived DOM and OTC molecules intensifying at higher DOM concentrations. The adsorption mechanisms were governed by both physical and chemical processes. Furthermore, the presence of Ca and Na ions significantly inhibited OTC adsorption. These insights advanced our understanding of the fate and risk of OTC in soil environments influenced by DOM, contributing to more informed agricultural and environmental management practices.
土霉素（OTC）在农业土壤中越来越多的存在引起了全球环境的关注。我们研究了两种热带农业土壤中 OTC 的环境行为和归宿，重点研究了沼气液中溶解有机质（DOM）的影响。采用三维激发-发射矩阵荧光光谱（3D-EEM）、傅里叶变换红外（FTIR）、X 射线光电子能谱（XPS）和紫外可见分光光度计（UV-vis）等技术，探讨了吸附机制。研究结果表明，沼气液衍生的 DOM 降低了 OTC 在土壤中的吸附，延长了达到吸附平衡的时间。具体来说，两种土壤对 OTC 的平衡吸附分别降低了 19.41%和 15.32%。这些吸附过程可以通过 Elovich、内扩散、线性和 Freundlich 热力学模型有效地进行模拟。热力学参数表明，OTC 在土壤上的吸附是自发和吸热的，随着 DOM 浓度的增加，沼气液衍生 DOM 和 OTC 分子之间的竞争相互作用加剧。吸附机制受物理和化学过程的共同控制。此外，Ca 和 Na 离子的存在显著抑制了 OTC 的吸附。这些发现增进了我们对受 DOM 影响的土壤环境中 OTC 的归宿和风险的认识，有助于更明智的农业和环境管理实践。
