School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China; National Observation and Research Station of Erhai Lake Ecosystem in Yunnan, Dali, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China; National Observation and Research Station of Erhai Lake Ecosystem in Yunnan, Dali, China; Yunnan Dali Research Institute of Shanghai Jiao Tong University, Dali, China.
Chemosphere. 2022 Jul;299:134377. doi: 10.1016/j.chemosphere.2022.134377. Epub 2022 Mar 29.
Dissolved organic matter (DOM) is a complex mixture of organic molecules that plays an important role in freshwater lake ecosystems. Excitation emission matrix-parallel factor analysis (EEM-PARAFAC) is an important tool for the identification and source analysis of DOM but is still inadequate for studying the differences and quantifying the contributions of different sources. Here, based on the maximum fluorescence intensities (Fmax) of the four fluorescent components (e.g., protein-like component C1, and the humic-like components C2, C3, C4) identified by EEM-PARAFAC, combined with large-scale data obtained from observations at Erhai Lake, we used partial least squares path modeling (PLS-PM) to improve the understanding of the migration and transformation mechanisms of DOM. The results showed that the phytoplankton and trophic state had greater impacts on DOM, while the impacts of sediment and inflow rivers were less significant. The results of the models that used nitrogen nutrients (N) and phosphorus nutrients (P) to separately indicate the trophic state suggested that the driving force of P on DOM was stronger than that of N in Erhai Lake. Among the four fluorescent components, the protein-like component with the largest relative proportion (41.98%) was mainly affected by phytoplankton, which was consistent with the autogenic characteristics obtained through spontaneous source index (BIX). The duality of the humic-like components was consistent with the duality of DOM through fluorescent index (FI). C3 had a higher sensitivity to the trophic state than the other components, and C2 received the greatest positive contribution from the rivers entering the lake. These results provide an improved insight into the influence of different sources on the behavior of DOM and demonstrate the potential of using PLS-PM to study the complex driving mechanism of aquatic biogeochemical parameters.
溶解有机物（DOM）是一种复杂的有机分子混合物，在淡水湖泊生态系统中起着重要作用。激发发射矩阵-平行因子分析（EEM-PARAFAC）是鉴定和来源分析 DOM 的重要工具，但仍不足以研究不同来源的差异和量化它们的贡献。在这里，基于 EEM-PARAFAC 鉴定的四个荧光成分（如类蛋白成分 C1 和腐殖质样成分 C2、C3、C4）的最大荧光强度（Fmax），结合洱海观测获得的大规模数据，我们使用偏最小二乘路径模型（PLS-PM）来提高对 DOM 迁移和转化机制的理解。结果表明，浮游植物和营养状态对 DOM 的影响更大，而沉积物和入流河流的影响较小。使用氮营养物（N）和磷营养物（P）分别指示营养状态的模型的结果表明，在洱海，P 对 DOM 的驱动力强于 N。在四个荧光成分中，相对比例最大（41.98%）的类蛋白成分主要受浮游植物的影响，这与通过自发源指数（BIX）获得的自生特征一致。腐殖质样成分的二元性与通过荧光指数（FI）获得的 DOM 的二元性一致。C3 对营养状态的敏感性高于其他成分，而 C2 从入湖河流获得的正贡献最大。这些结果提供了对不同来源对 DOM 行为影响的深入了解，并展示了使用 PLS-PM 研究水生生物地球化学参数复杂驱动机制的潜力。
