作者：Yang, Y., Wang, H., He, J., Yang, W., Cai, H., Jiao, L., Ma, S., Sun, X., Jilbert, T., Paerl, H. & Jeppesen, E.

Phosphorus (P) release from lake sediments is widely recognized as a critical barrier to mitigate eutrophication, as it continuously provides nutrient sources (i.e. internal loading) to support phytoplankton blooms. However, for large lakes the spatial patterns and mechanisms of internal P loading remain poorly understood due to extensive spatial heterogeneity. To address these knowledge gaps, we selected Lake Dianchi-a large subtropical plateau lake in China that has suffered from decades of eutrophication and frequent cyanobacterial blooms. We integrated a lake-wide vertical profile analysis of P binding forms with assessments of nutrient release potential through high-resolution thin film diffusion gradient technology (DGT). The results revealed distinct spatial differences in sediment P dynamics between the northern and southern regions of the lake. In the northern bay, sediment profiles were characterized by low DGT-labile Fe/P ratios and high DGT-labile P and/or NH4Cl-P contents; the reductive dissolution of Fe-bound P (BD-P) dominated the short-term (decadal scale, similar to 10 years) P release (contributing 84.6 %). In contrast, sediment profiles from the southern region were characterized by high DGT-Fe/P ratios and low DGT-labile P and/or NH4Cl-P contents; organic P (NaOH-nrP) remineralization dominated (contributing 90.7 %) the short-term P release. We furthermore found a significant increase in the contributions of Al-bound P (NaOH-rP) and Ca-bound P (HCl-P) to P release on a long-term scale (similar to 50 years). The complex interplay among redox-driven Fe-P coupling, organic P mineralization, and legacy P remobilization creates self-reinforcing feedback loops that challenge lake-wide management.

湖泊沉积物磷释放被广泛认为是缓解富营养化的关键障碍，因为它持续提供营养源（即内负荷）以支撑浮游植物水华。然而，对于大型湖泊而言，由于空间异质性极大，内源磷负荷的空间格局与机制仍知之甚少。为弥补上述认知空白，我们选取了滇池——一个遭受数十年富营养化且蓝藻水华频发的中国亚热带大型高原湖泊。我们将全湖垂直剖面的磷结合形态分析与通过高分辨率薄膜扩散梯度技术评估的营养盐释放潜力相整合。结果揭示了该湖南北区域之间沉积物磷动态的显著空间差异。在北部湖湾，沉积物剖面以低 DGT-不稳定态铁/磷比和高 DGT-不稳定态磷及/或氯化铵提取态磷含量为特征；铁结合态磷的还原溶解主导了短期（十年尺度，约10年）的磷释放（贡献率达84.6%）。相比之下，南部区域的沉积物剖面则以高 DGT-铁/磷比和低 DGT-不稳定态磷及/或氯化铵提取态磷含量为特征；有机磷的再矿化主导了短期的磷释放（贡献率达90.7%）。我们进一步发现，在长期尺度（约50年）上，铝结合态磷和钙结合态磷对磷释放的贡献显著增加。氧化还原驱动的铁-磷耦合、有机磷矿化与遗留磷再活化之间复杂的相互作用，形成了自我强化的反馈循环，给全湖管理带来了挑战。

（来源：Water Research 2026  DOI: 10.1016/j.watres.2026.125745）