Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Hainan University, Haikou 570228, China; Center for Eco-Environment Restoration Engineering of Hainan Province, Hainan University, Haikou 570228, China; Key Laboratory of Environmental Toxicology, Hainan University, Ministry of Education, Haikou 570228, China.
Hainan Key Laboratory of Tropical Eco-circuling Agriculture, Institute of Environment and Plant Protection, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China; Ministry Key Laboratory of Low-carbon Green Agriculture in Tropical region of China, Institute of Environment and Plant Protection, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
Ecotoxicol Environ Saf. 2024 Feb;271:115953. doi: 10.1016/j.ecoenv.2024.115953. Epub 2024 Jan 19.
The widespread use of biogas slurry could potentially raise the environmental risk of antibiotics. Dissolved organic matter (DOM), as the most active part of biogas slurry, was able to interact with antibiotics and play a crucial role in the structure and function of soil and aquatic ecosystems. The recent shifts in global climate patterns have garnered significant attention due to their substantial impact on temperature, thereby exerting a direct influence on the characteristics of DOM and subsequently on the environmental behavior of antibiotics. However, there is limited research concerning the impact of temperature on the binding of DOM and antibiotics. Thus, this study aimed to explore the temperature-dependent structural transformation and driving factors of biogas slurry-derived DOM (BSDOM). Additionally, the binding characteristics between BSDOM and the commonly used antibiotic norfloxacin (NOR) at different temperatures were studied by using multi spectroscopic methods and two-dimensional correlation spectroscopy (2D-COS) analysis. The results suggested that the temperature-dependent structural transformation of BSDOM was reversible, with a slight lag in the transition temperature under cooling (13 °C for heating and 17 °C for cooling). Heating promoted the conversion of protein-like to humic-like substances while cooling favored the decomposition of humic-like substances. BSDOM and NOR were static quenching, with oxygen-containing functional groups such as C-O and -OH playing an important role. Temperature influenced the order of binding, the activity of the protein fraction, and its associated functional groups. At temperatures of 25 °C and 40 °C, the fluorescent components were observed to exhibit consistent binding preferences, whereby the humic-like component demonstrated a greater affinity for NOR compared to the protein-like component. However, the functional group binding order exhibited an opposite trend. At 10 °C, a new protein-like component appeared and bound preferentially to NOR, when no C-O stretch corresponding to the amide was observed. The finding will contribute to a comprehensive understanding of the interaction mechanisms between DOM and antibiotics under climate change, as well as providing a theoretical basis to reduce the environmental risks of biogas slurry and antibiotics.
沼气液的广泛使用可能会增加抗生素的环境风险。作为沼气液中最活跃的部分，溶解有机物（DOM）能够与抗生素相互作用，在土壤和水生生态系统的结构和功能中发挥关键作用。由于全球气候模式的变化对温度有重大影响，因此最近它们受到了极大的关注，这直接影响了 DOM 的特性，并进而影响了抗生素的环境行为。然而，关于温度对 DOM 和抗生素结合的影响的研究还很有限。因此，本研究旨在探索沼气液衍生 DOM（BSDOM）的温度依赖性结构转化及其驱动因素。此外，还通过使用多种光谱方法和二维相关光谱（2D-COS）分析研究了不同温度下 BSDOM 与常用抗生素诺氟沙星（NOR）之间的结合特性。结果表明，BSDOM 的温度依赖性结构转化是可逆的，在冷却（加热 13°C，冷却 17°C）下过渡温度略有滞后。加热促进了蛋白质样物质向腐殖质样物质的转化，而冷却则有利于腐殖质样物质的分解。BSDOM 和 NOR 是静态猝灭的，含氧官能团如 C-O 和 -OH 起着重要作用。温度影响结合顺序、蛋白质部分的活性及其相关官能团。在 25°C 和 40°C 下，观察到荧光成分表现出一致的结合偏好，其中腐殖质样成分与 NOR 的亲和力大于蛋白质样成分。然而，官能团结合顺序表现出相反的趋势。在 10°C 时，出现了一个新的蛋白质样成分，并且优先与 NOR 结合，而没有观察到对应于酰胺的 C-O 伸展。这一发现将有助于全面了解气候变化下 DOM 和抗生素之间的相互作用机制，并为减少沼气液和抗生素的环境风险提供理论依据。
