Shang Yingxin, Song Kaishan, Wen Zhidan, Lai Fengfa, Liu Ge, Tao Hui, Yu Xiangfei
Northeast Institute of Geography and Agroecology, CAS, Changchun, 130102, China.
Jilin Jianzhu University, Changchun, 130118, China.
Environ Sci Ecotechnol. 2025 May 12;25:100570. doi: 10.1016/j.ese.2025.100570. eCollection 2025 May.
Chromophoric dissolved organic matter (CDOM), characterized by unique optical properties, is an essential indicator for understanding aquatic organic matter dynamics within global carbon cycles. Soil erosion, a major source of CDOM received by lakes, transports terrestrial organic matter to water bodies, altering sources, bioavailability and molecular complexity of CDOM significantly. Yet, the spatial patterns of CDOM in lakes from different soil erosion regions are still unknown. Here, we developed a robust machine learning framework (RMSE = 0.87 m) to estimate CDOM concentrations in lakes by integrating over 1300 water samples with Landsat 8 OLI surface reflectance data. We then applied this model to map the spatial distribution of CDOM across lakes larger than 0.1 km in 2020. Our analysis revealed distinct spatial patterns, with mean CDOM absorption coefficients at 355 nm of 3.73 m in freeze-thaw erosion regions, 6.31 m in wind erosion regions, and 3.72 m in hydraulic erosion regions, reflecting significant variations driven by erosion intensity. Two axes of PCA analysis explained over 48 % variations of CDOM for different soil erosion types. Chemical characterization indicated that polycyclic aromatic predominated in wind and hydraulic erosion regions, whereas freeze-thaw erosion regions exhibited higher proportions of peptides and unsaturated aliphatic compounds. This study highlights the crucial connection between terrestrial soil erosion processes and aquatic DOM composition, providing vital insights for evaluating global carbon cycling and carbon storage within inland ecosystems.
发色溶解有机物（CDOM）具有独特的光学性质，是了解全球碳循环中水生有机物动态的重要指标。土壤侵蚀是湖泊中CDOM的主要来源，它将陆地有机物输送到水体中，显著改变了CDOM的来源、生物可利用性和分子复杂性。然而，不同土壤侵蚀区域湖泊中CDOM的空间格局仍然未知。在此，我们开发了一个强大的机器学习框架（均方根误差=0.87 m），通过将1300多个水样与陆地卫星8号OLI地表反射率数据相结合来估算湖泊中的CDOM浓度。然后，我们应用该模型绘制了2020年面积大于0.1 km的湖泊中CDOM的空间分布。我们的分析揭示了不同的空间格局，冻融侵蚀区域355 nm处的平均CDOM吸收系数为3.73 m，风蚀区域为6.31 m，水力侵蚀区域为3.72 m，这反映了侵蚀强度驱动的显著差异。主成分分析的两个轴解释了不同土壤侵蚀类型下CDOM超过48%的变化。化学特征表明，多环芳烃在风蚀和水力侵蚀区域占主导地位，而冻融侵蚀区域的肽和不饱和脂肪族化合物比例较高。这项研究突出了陆地土壤侵蚀过程与水生DOM组成之间的关键联系，为评估内陆生态系统中的全球碳循环和碳储存提供了重要见解。
