溶解有机质对来自中国北方黄河的沙质土壤（组分）上诺氟沙星吸附的影响。
Effects of dissolved organic matter on the adsorption of norfloxacin on a sandy soil (fraction) from the Yellow River of Northern China.
机构信息
School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China.
Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China; State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510655, China.
出版信息
Sci Total Environ. 2022 Nov 20;848:157495. doi: 10.1016/j.scitotenv.2022.157495. Epub 2022 Jul 20.
Dissolved organic matter (DOM), which exists widely in the environment, coming from different sources, may greatly affect the adsorption of antibiotics. However, the adsorption mechanisms of antibiotics in a sandy soil and the effects of DOM from different sources on the adsorption remain poorly understood. This study systematically investigated the adsorption characteristics of norfloxacin (NOR) onto a sandy soil obtained from the banks of Xi'an in Yellow River and in the presence of three DOM including HDOM (commercially available humic acids), LDOM (derived from fallen leaves) and MDOM (derived from cattle manure). Elemental analysis, UV-vis spectroscopy, 3D-EEM, XPS, TOC, SEM, and FTIR were used to analyze the adsorption mechanism. It was found that all the DOM sources we used could reduce the adsorption of NOR on sandy soil and prolong the reaction time to reach adsorption equilibrium. The decreasing adsorption capacities of NOR by the three types of DOM (10 mg/L) followed the order as: HDOM < LDOM < MDOM, which was related to their aromaticity, polarity and hydrophobicity. These adsorption processes of NOR on sandy soil in the presence of DOM were well fitted by Double-chamber first-order kinetics, Linear model and Freundlich models. Besides, the adsorption reaction was endothermic and spontaneous. Adsorption competition of DOM molecules with NOR, or formation of DOM-NOR complexes in solution resulted in a decrease of sandy soil adsorption capacity. Correspondingly, co-adsorption and cumulative adsorption were also considered to be the key processes that determined NOR adsorption towards sandy soil after adding DOM. Moreover, the adsorption of NOR onto sandy soil exhibited strong pH-dependent characteristic and NOR might be more easily leached from sandy soil in the aquifer at an alkaline pH. High-ion strength suppressed the adsorption. These results would help to understand the fate and risk of NOR under the action of different DOM.
溶解有机质（DOM）广泛存在于环境中，来源于不同的来源，可能会极大地影响抗生素的吸附。然而，抗生素在沙质土壤中的吸附机制以及不同来源的 DOM 对吸附的影响仍知之甚少。本研究系统地研究了诺氟沙星（NOR）在黄河岸边采集的沙质土壤以及三种 DOM（商品腐殖酸 HDOM、落叶源 LDOM 和牛粪源 MDOM）存在下的吸附特性。采用元素分析、紫外可见光谱、三维荧光光谱、X 射线光电子能谱、总有机碳、扫描电子显微镜和傅里叶变换红外光谱等手段分析了吸附机制。结果表明，我们使用的所有 DOM 来源都可以减少 NOR 在沙质土壤上的吸附，并延长达到吸附平衡的反应时间。三种类型的 DOM（10mg/L）对 NOR 的吸附容量降低顺序为：HDOM＜LDOM＜MDOM，这与它们的芳香性、极性和疏水性有关。这些 DOM 存在下 NOR 在沙质土壤上的吸附过程很好地符合双室一级动力学、线性模型和 Freundlich 模型。此外，吸附反应是吸热和自发的。DOM 分子与 NOR 的吸附竞争，或 DOM-NOR 配合物在溶液中的形成，导致沙质土壤吸附容量降低。相应地，共吸附和累积吸附也被认为是确定 DOM 添加后 NOR 对沙质土壤吸附的关键过程。此外，NOR 在沙质土壤上的吸附表现出强烈的 pH 依赖性，在碱性 pH 条件下，NOR 可能更容易从含水层中的沙质土壤中淋滤出来。高离子强度抑制了吸附。这些结果有助于理解在不同 DOM 作用下 NOR 的命运和风险。
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