采煤沉陷区水土界面DOM迁移转化规律

Migration and Transformation of DOM at the Water-Soil Interface in Coal Mining Subsidence Areas

摘要: 系统研究了采煤沉陷区水体和土壤中溶解性有机质(DOM)的迁移、转化及分子特征。通过紫外–可见光光谱(UV-Vis)、三维荧光光谱(3D-EEMs)与FT-ICR MS技术，分析了沉陷区水体和土壤中的DOM特性与组成。结果表明，沉陷区水体和土壤中的DOM主要由类腐殖质和类蛋白质组成。水体中的类腐殖质和类蛋白质组分分别占56.08%和42.92%；土壤中的类腐殖质组分占70.19%，类蛋白质组分占29.81%。土壤和水体中的DOM呈现出高度相似的荧光特征，水体DOM主要由自生源(微生物或藻类产物)组成，而土壤则受陆源输入影响较大。研究还发现，DOM在水土界面中的迁移与转化过程与外源输入(如农业径流和采煤沉陷区沉积物)密切相关，DOM特征与氮源(氨氮和硝态氮)水平高度相关，暗示了氮在DOM生物地球化学循环中的潜在关键作用。通过FT-ICR MS分析，水体DOM中的木质素类有机质占主导(65%~68%)，但蛋白质、脂类及氨基糖的比例有所上升，表明有机质在迁移过程中发生了生物转化。而土壤DOM则以木质素和缩合芳香烃结构为主，显示出较高的芳香化和氧化特征，表明在湿地环境中，土壤中的有机物经历了较长时间的分解过程。

Abstract: The migration, transformation, and molecular characteristics of dissolved organic matter (DOM) in water and soil in coal mining subsidence areas were systematically investigated. The characteristics and composition of DOM in water and soil in the subsidence area were analyzed using ultraviolet-visible spectroscopy (UV-Vis), three-dimensional fluorescence spectroscopy (3D-EEMs), and FT-ICR MS. The results showed that DOM in water and soil in the subsidence area was primarily composed of humus-like and protein-like components. Humus-like and protein-like components accounted for 56.08% and 42.92% of the water, respectively; humus-like components accounted for 70.19% of the soil, and protein-like components accounted for 29.81%. DOM in soil and water exhibited highly similar fluorescence characteristics. DOM in water is primarily composed of autogenous sources (microbial or algal products), while soil is significantly influenced by terrestrial inputs. The study also found that the migration and transformation of DOM at the water-soil interface is closely related to external inputs (such as agricultural runoff and sediments from coal mining subsidence areas). DOM characteristics are highly correlated with nitrogen source levels (ammonia and nitrate), suggesting a potentially critical role for nitrogen in the biogeochemical cycle of DOM. FT-ICR MS analysis revealed that lignin-based organic matter predominated in aquatic DOM (65%~68%), but the proportions of proteins, lipids, and amino sugars increased, indicating that organic matter underwent biotransformation during migration. Soil DOM, on the other hand, was primarily composed of lignin and condensed aromatic hydrocarbon structures, exhibiting high levels of aromatization and oxidation, suggesting that organic matter in the soil undergoes a prolonged decomposition process in wetland environments.