Abstract In large and shallow lakes, the role of the redox-related release of phosphorus (P) from sediments has remained in the shadow of sediment resuspension. In the current study, we concentrated on this knowledge gap regarding factors controlling lake water quality. We combined long-term monitoring data with the studies on sediment P mobility in August 2018 by measuring redox potential, pore water concentrations of soluble reactive phosphorus (SRP), dissolved iron (Fe), sediment P fractions, and by calculating diffusive P flux. Using lake water total P (TP) concentrations for 21 years (1997–2018), we quantified internal P load based on water column summer increase of TP (ILin situ). Significant positive correlations were found between the diffusive P flux and the Fe-bound P concentration in the sediment for conditions of well-oxidized sediment surfaces. The analysis of long-term data showed that P mobilized in sediments is likely to be released via sediment disturbances. Sediment resuspension is favoured by decreased water level during late summer-early autumn. Additionally, the release of P from anoxic sediment surfaces is also possible, as was indicated by significant positive correlations of ILin situ with the anoxic factor (a measure of extent of anoxia) and August water temperature. The potential P release from anoxic sediment surfaces contributed about 80% to ILin situ in the northern basin, and about 280% in the more productive southern basin. Hence, the redox-related P release seems to sustain the high productivity of these large and shallow lake basins and is supported by sediment resuspension as a transport mechanism.

中文翻译：

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Peipsi 大浅湖沉积物中磷的氧化还原相关释放：来自沉积物研究和长期监测数据的证据

摘要 在大而浅的湖泊中，沉积物中磷（P）与氧化还原相关的释放作用一直处于沉积物再悬浮的阴影之下。在当前的研究中，我们专注于有关控制湖泊水质因素的知识差距。我们通过测量氧化还原电位、可溶性活性磷 (SRP)、溶解铁 (Fe)、沉积物 P 分数和计算扩散 P 通量的氧化还原电位、孔隙水浓度，将长期监测数据与 2018 年 8 月对沉积物 P 迁移率的研究相结合。使用 21 年（1997-2018 年）的湖水总磷（TP）浓度，我们量化了基于夏季 TP 水柱增加（ILin situ）的内部磷负荷。在沉积物表面氧化良好的条件下，扩散 P 通量与沉积物中的 Fe 结合 P 浓度之间存在显着的正相关。长期数据分析表明，沉积物中迁移的磷很可能通过沉积物扰动释放。夏末秋初水位降低有利于沉积物再悬浮。此外，P 从缺氧沉积物表面释放也是可能的，正如原位 IL 与缺氧因子（缺氧程度的度量）和 8 月水温的显着正相关所表明的那样。缺氧沉积物表面的潜在磷释放对北部盆地的原位 IL 贡献了约 80%，在生产力更高的南部盆地贡献了约 280%。因此，