Liu Yan-Jun, Yang He-Yun, Gao Shu-Xian, Li Zheng-Hao, Hu Yan-Yun, Zheng Xing, Sheng Guo-Ping
CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China.
State Key Laboratory of Eco-Hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an 710048, China.
Water Res. 2025 Jan 1;268(Pt A):122584. doi: 10.1016/j.watres.2024.122584. Epub 2024 Oct 6.
Adsorption fractionation of dissolved organic matter (DOM) induced by soil minerals is a common geochemical process, which has been widely documented on natural DOM. Hydrochar is a promising functional material in soil remediation but can continuously release abundant endogenic DOM with potential biotoxicity. However, adsorption fractionation at molecular level and its influence on toxicity evolution of hydrochar-derived DOM (HDOM) at genetic level at the soil-water interface remain poorly understood. Herein, we investigated the molecular fractionation of HDOM on three typical soil iron minerals (i.e., ferrihydrite, goethite, and hematite). Results from ultrahigh-resolution mass spectrum showed that HDOM molecules with high molecular weight and high contents of unsaturated oxidized or aromatic structures (e.g., unsaturated phenolic compounds, polyphenols, and organic acids) were preferentially absorbed by iron oxyhydroxides, while aliphatic molecules and poorly oxygenated compounds (e.g., hydrocarbon, phenols, and alcohols) were retained in aqueous phase. Furthermore, we quantitatively evaluated their genotoxicity variation using a toxicogenomics assay using green fluorescence protein-fused whole-cell array, and results showed that oxidative, protein, membrane, and DNA stresses were primary responses upon exposure to original HDOM. Interface fractionation induced by iron oxyhydroxides significantly reduced genotoxicity of HDOM, especially for oxidative, membrane and DNA stresses. Overall, the selective absorption of HDOM molecules by iron oxyhydroxides shifted its biotoxicity, which might change the ecological effects of hydrochar amendment, e.g., microbial community structure, environmental pollutant transformation, and even the ecological function of terrestrial and aquatic ecosystems. These findings would contribute to unraveling the environmental geochemistry process of HDOM in the natural soil-water interface and provide a new insight into the biotoxicity of hydrochar usage to terrestrial and aquatic environments.
土壤矿物质对溶解有机物（DOM）的吸附分级是一种常见的地球化学过程，这在天然DOM方面已有广泛记载。生物炭是土壤修复中一种很有前景的功能材料，但它会持续释放大量具有潜在生物毒性的内源DOM。然而，在土壤-水界面，分子水平的吸附分级及其对生物炭衍生DOM（HDOM）遗传水平毒性演变的影响仍知之甚少。在此，我们研究了HDOM在三种典型土壤铁矿物（即水铁矿、针铁矿和赤铁矿）上的分子分级。超高分辨率质谱结果表明，具有高分子量以及高含量不饱和氧化或芳香结构（如不饱和酚类化合物、多酚和有机酸）的HDOM分子优先被羟基氧化铁吸附，而脂肪族分子和低氧化态化合物（如烃类、酚类和醇类）则保留在水相中。此外，我们使用绿色荧光蛋白融合全细胞阵列的毒理基因组学分析定量评估了它们的遗传毒性变化，结果表明，氧化应激、蛋白质应激、膜应激和DNA应激是接触原始HDOM后的主要反应。羟基氧化铁诱导的界面分级显著降低了HDOM的遗传毒性，尤其是氧化应激、膜应激和DNA应激方面。总体而言，羟基氧化铁对HDOM分子的选择性吸附改变了其生物毒性，这可能会改变生物炭改良的生态效应，例如微生物群落结构、环境污染物转化，甚至陆地和水生生态系统的生态功能。这些发现将有助于揭示天然土壤-水界面HDOM的环境地球化学过程，并为生物炭在陆地和水生环境中的使用所产生的生物毒性提供新的见解。
