Dissolved organic matter (DOM) in sediment pore water plays a key role in lake water quality, complexation of the contaminants, biogeochemical cycles, and even climate. To better understand the vertical dynamics and characteristics of DOM among pore water profiles, we investigated concentrations, chemical structures, and benthic fluxes of DOM in plateau lake sediments via stoichiometric analysis, ultraviolet–visible (UV–vis) absorption, three-dimensional fluorescence matrix spectroscopy (EEMs), and parallel factor model (PARAFAC). The results revealed that dissolved organic carbon (DOC), concurrent with chromophoric DOM (CDOM) and fluorescent DOM (FDOM), tended to accumulate in the anaerobic deeper layers. These trends also demonstrated a good agreement with the ammonium nitrogen (NH₄⁺-N) concentration, implying that the pathway of DOM dynamics was closely related to the redox state. The EEMs-PARAFAC model revealed that DOM in pore water mostly consisted of two terrestrial humic-like components (average contribution:> 60%) followed by microbial and tryptophan-like components, respectively. Terrestrial humic-like components were relatively stable, and their abundance was positively correlated with the FDOM level (p < 0.05). The changes of aromatic, molecular weight, and humification degree of DOM were possibly driven by microbial activities at different depths. Moreover, benthic flux estimations indicated that DOM and the total dissolved nitrogen (TDN) in inland sediments were potential sources for the overlying water and possibly affected the quality and ecological safety of lake water bodies.

沉积物孔隙水中的溶解有机物（DOM）在湖泊水质，污染物的络合，生物地球化学循环乃至气候中起着关键作用。为了更好地了解孔隙水剖面中DOM的垂直动态和特征，我们通过化学计量分析，紫外可见（UV-vis）吸收，三维荧光矩阵研究了高原湖泊沉积物中DOM的浓度，化学结构和底流光谱（EEM）和并行因子模型（PARAFAC）。结果表明，溶解的有机碳（DOC），与发色DOM（CDOM）和荧光DOM（FDOM）同时，倾向于在厌氧的较深层中积累。这些趋势还表明与铵态氮（NH ₄ ⁺-N）浓度，这表明DOM动力学途径与氧化还原状态密切相关。EEMs-PARAFAC模型显示，孔隙水中的DOM主要由两种陆地腐殖质样组分（平均贡献度：> 60％）组成，其后分别是微生物和色氨酸样组分。陆地腐殖质样成分相对稳定，其丰度与FDOM水平呈正相关（p <0.05）。DOM的芳香，分子量和腐殖化程度的变化可能是由不同深度的微生物活动驱动的。此外，底栖通量估算表明，内陆沉积物中的DOM和总溶解氮（TDN）是上覆水的潜在来源，并可能影响湖泊水体的质量和生态安全。