Ecological regionalization significantly influences the characteristics of lake sedimentary dissolved organic matter

China possesses numerous lakes characterized by diverse natural environments and uneven socioeconomic development, resulting in pronounced geographical variations among lakes located in different regions. The properties of water-extractable sediment (DOM) in lakes across distinct ecological regions exhibit significant differences. However, existing research has primarily focused on water-extractable sediment DOM in individual lakes or small-scale watersheds, with limited systematic comparisons spanning climate gradients and anthropogenic activity intensities. Therefore, sediment samples were collected from 36 lakes across four ecological lake regions in China to investigate the characteristics of water-extractable sediment DOM. We employed ultraviolet-visible spectroscopy and three-dimensional excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis to characterize the compositional and structural features of water-extractable sediment DOM. The Mong-Xin Plateau Lakes (MPL) exhibited elevated water-extractable sediment DOM content. Both the Yun-Gui Plateau (YGP) and the Eastern Plain Lakes (EPL) showed water-extractable sediment DOM dominated by autochthonous protein-like components derived from microbial metabolism. MPL and Northeast Plain Lakes (NPL) demonstrated mixed terrestrial-autochthonous water-extractable sediment DOM characteristics. The sedimentary environmental factors, particularly dissolved organic carbon concentration, pH, and total nitrogen contributed most significantly to DOM variability. High aridity index was associated with higher proportions of humic-like DOM, possibly due to evaporative concentration effects under semi-arid conditions. Extensive grassland coverage contributed to terrestrial humic substances, while intensive agricultural activities and high population density were associated with higher proportions of autochthonous water-extractable sediment DOM, potentially reflecting increased nutrient inputs and microbial production. This research helps bridge regional knowledge fragmentation and provides critical parameters for evaluating lake water-extractable sediment DOM characteristics under climate change scenarios, thereby supporting the development of integrated watershed management strategies and water quality improvement measures.