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<p>The high organic content in freshwater sediments is often linked to methane (CH<sub>4</sub>) presence and phosphorus (P) release to water column. However, there are few investigations on an impact of the CH<sub>4</sub>-oxidation pathway for P retention in freshwater systems. In this study, we investigated an impact of anaerobic methane oxidation (AOM) by iron (Fe) oxyhydroxide on P loading from sediments. We performed a field experimental study and a modelling balance approach. The study site is a typical northern temperate freshwater ecosystem for northern Laurentian Great lakes catchment around Lake Huron. The redox-sensitive P binding form, linked to P bound on Fe- and manganese-(hydro) oxides was the dominant TP fraction from 0 to 30&#xa0;cm. The CH<sub>4</sub> concentration reached the maximum concentration of 109&#xa0;μM at 24&#xa0;cm in the sediment. We suggest one possible explanation for SRP enrichment at 16–20&#xa0;cm may be attributed to Fe (III) reduction coupled to AOM (Fe-AOM), which promotes the dissolution of Fe-oxyhydroxides and the subsequent release of adsorbed phosphate. This interpretation is supported by concurrent CH₄ consumption and the prevailing geochemical conditions in this depth interval. Fe-AOM may contribute up to 79.5&#xa0;µmol&#xa0;m⁻<sup>2</sup>&#xa0;day⁻<sup>1</sup> P release. Vivianite was identified in deeper sediment layers, below the depth interval where Fe-AOM activity is suggested. Our findings underscore the necessary of comprehending the impact of Fe-AOM, which is documented in numerous freshwater sediments, on the P cycle in freshwater system.</p>

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Anaerobic methane oxidation can impact phosphorus retention in lake sediments

  • 期刊论文

  • 发表日期：

    2025年8月1日

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  • Xiaoqing Shao,
  • Khoren Avetisyan,
  • David Sweetnam,
  • Maria Dittrich

摘要

The high organic content in freshwater sediments is often linked to methane (CH4) presence and phosphorus (P) release to water column. However, there are few investigations on an impact of the CH4-oxidation pathway for P retention in freshwater systems. In this study, we investigated an impact of anaerobic methane oxidation (AOM) by iron (Fe) oxyhydroxide on P loading from sediments. We performed a field experimental study and a modelling balance approach. The study site is a typical northern temperate freshwater ecosystem for northern Laurentian Great lakes catchment around Lake Huron. The redox-sensitive P binding form, linked to P bound on Fe- and manganese-(hydro) oxides was the dominant TP fraction from 0 to 30 cm. The CH4 concentration reached the maximum concentration of 109 μM at 24 cm in the sediment. We suggest one possible explanation for SRP enrichment at 16–20 cm may be attributed to Fe (III) reduction coupled to AOM (Fe-AOM), which promotes the dissolution of Fe-oxyhydroxides and the subsequent release of adsorbed phosphate. This interpretation is supported by concurrent CH₄ consumption and the prevailing geochemical conditions in this depth interval. Fe-AOM may contribute up to 79.5 µmol m⁻2 day⁻1 P release. Vivianite was identified in deeper sediment layers, below the depth interval where Fe-AOM activity is suggested. Our findings underscore the necessary of comprehending the impact of Fe-AOM, which is documented in numerous freshwater sediments, on the P cycle in freshwater system.