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<p>Internal phosphorus (P) is a critical driver of eutrophication and algal blooms, yet the dynamics of P at the sediment–water interface during different algal periods remain poorly understood. Here, field investigations were conducted pre-, during, and post-algal blooms to reveal the temporal variations in P speciation in both sediment and overlying water, and to evaluate the associated P transformation processes and internal release risk in the eutrophic Bali Lake. Sediment labile P was dominated by iron/aluminum-bound P (Fe/Al–P) and moderately active organic P (MA–P). Compared to the levels pre-algal blooms, total P and MA–P in sediments increased continuously during and post-algal blooms. In contrast, weakly adsorbed P (WA–P), potentially active P (PA–P), neutral phosphatase activity, and phosphate exchange potential increased by 2.6-, 1.4-, 1.6-, and 14-fold during algal blooms, respectively, but declined afterward. Conversely, Fe/Al–P decreased by 46.5% during algal blooms and increased by 1.53-fold thereafter. In the overlying water, dissolved inorganic P was assimilated by algae during algal blooms and converted to dissolved organic and particulate forms, which were subsequently remineralized to dissolved inorganic P post-algal blooms. Mantel tests identified PA–P, WA–P and dissolved oxygen as key regulators of phosphate exchange potential, whereas MA–P and temperature were the primary drivers of neutral phosphatase activity. Our results demonstrate that warm, hypoxic conditions during algal blooms promote the reductive dissolution of Fe/Al–P and the mineralization of MA–P into WA–P and PA–P, thereby heightening the risk of internal P release in eutrophic lakes.</p>

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Transformation and internal release of phosphorus at the sediment–water interface across distinct algal periods in a eutrophic lake of the Yangtze River Basin

  • 期刊论文

  • 发表日期：

    2026年6月26日

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  • Rongfu Li,
  • Wencheng Liao,
  • Zhennan Xiong,
  • Cheng Jiang,
  • Shuanglin Gui,
  • Yajun Liu,
  • Hailin You,
  • Yongming Wu

摘要

Internal phosphorus (P) is a critical driver of eutrophication and algal blooms, yet the dynamics of P at the sediment–water interface during different algal periods remain poorly understood. Here, field investigations were conducted pre-, during, and post-algal blooms to reveal the temporal variations in P speciation in both sediment and overlying water, and to evaluate the associated P transformation processes and internal release risk in the eutrophic Bali Lake. Sediment labile P was dominated by iron/aluminum-bound P (Fe/Al–P) and moderately active organic P (MA–P). Compared to the levels pre-algal blooms, total P and MA–P in sediments increased continuously during and post-algal blooms. In contrast, weakly adsorbed P (WA–P), potentially active P (PA–P), neutral phosphatase activity, and phosphate exchange potential increased by 2.6-, 1.4-, 1.6-, and 14-fold during algal blooms, respectively, but declined afterward. Conversely, Fe/Al–P decreased by 46.5% during algal blooms and increased by 1.53-fold thereafter. In the overlying water, dissolved inorganic P was assimilated by algae during algal blooms and converted to dissolved organic and particulate forms, which were subsequently remineralized to dissolved inorganic P post-algal blooms. Mantel tests identified PA–P, WA–P and dissolved oxygen as key regulators of phosphate exchange potential, whereas MA–P and temperature were the primary drivers of neutral phosphatase activity. Our results demonstrate that warm, hypoxic conditions during algal blooms promote the reductive dissolution of Fe/Al–P and the mineralization of MA–P into WA–P and PA–P, thereby heightening the risk of internal P release in eutrophic lakes.