Impact of iron addition on phosphorus dynamics in sediments of a shallow peat lake 10 years after treatment

Melanie A. Münch; Rianne van Kaam; Karel As; Stefan Peiffer; Gerard ter Heerdt; Caroline P. Slomp; Thilo Behrends

doi:10.1016/j.watres.2023.120844

Impact of iron addition on phosphorus dynamics in sediments of a shallow peat lake 10 years after treatment

Melanie A. Münch^*
, Rianne van Kaam
, Karel As
, Stefan Peiffer
, Gerard ter Heerdt
, Caroline P. Slomp
, Thilo Behrends

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Internal phosphorus (P) loading is a key water quality challenge for shallow lakes. Addition of iron (Fe) salts has been used to enhance P retention in lake sediments. However, its effects on sediment geochemistry are poorly studied, albeit pivotal for remediation success. Here, we assess the factors controlling the retention of P and long-term effects following application of FeCl₃ (0.5–1 mol Fe/m², 2010) in the eutrophic, shallow peat lake Terra Nova (the Netherlands). Treatment reduced P levels in the lake for two years, but afterwards summer release of P intensified, resulting in higher surface water P concentrations than before treatment. Porewater and sediment analyses indicate that the majority of the added Fe is still undergoing redox cycling within the top 10 cm of sediment accounting for the binding of up to 70 % of sedimentary P. Sequential extractions further suggest that organic matter (OM) plays a key role in the resulting P and Fe dynamics: While reduction of P binding Fe(III) phases results in P release to porewaters, the produced Fe²⁺ remains bound to the solid phase presumably stabilized by OM. This causes P release from the sediments in excess to Fe during temporary low oxygen conditions in summer months, as confirmed by whole core flux incubation experiments. Quantitative coprecipitation of P with Fe upon reoxygenation of the water body is then impossible, leading to a gradual increase in surface water P. This first long-term study on a shallow peat lake underpins the role of OM for Fe cycling and the need to carefully consider the sediment properties and diagenetic pathways in the planning of Fe-amendments.

Original language	English
Article number	120844
Number of pages	11
Journal	Water Research
Volume	248
DOIs	https://doi.org/10.1016/j.watres.2023.120844
Publication status	Published - 1 Jan 2024

Bibliographical note

Publisher Copyright:
© 2023 The Author(s)

Funding

This research was part of the P-Trap project funded by the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 813438 . We acknowledge the Utrecht University laboratory staff H.C. de Waard, J.M. van Aken, J.J. Mulder, J.J. van Tongeren, J.G.J. Visser, J.P. de Witte, M. Hamers and T.H.H. Claessen for chemical analysis, the fabrication of lab-ware, and general support, A. Cinjee from Deltares for help with field equipment and sampling and Dr. N.A.G.M. van Helmond and Dr. M. Hermans for consultation and help with laboratory work. We further thank Dr. Gertrud Nürnberg and an anonymous reviewer for their constructive feedback.

Funders	Funder number
H2020 Marie Skłodowska-Curie Actions	813438
Horizon 2020

Keywords

Internal phosphorus loading
Iron treatment
Lake restoration
Sediment geochemistry
Shallow peat lake

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1-s2.0-S0043135423012848-mainFinal published version, 7.35 MBLicence: CC BY

Cite this

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title = "Impact of iron addition on phosphorus dynamics in sediments of a shallow peat lake 10 years after treatment",

abstract = "Internal phosphorus (P) loading is a key water quality challenge for shallow lakes. Addition of iron (Fe) salts has been used to enhance P retention in lake sediments. However, its effects on sediment geochemistry are poorly studied, albeit pivotal for remediation success. Here, we assess the factors controlling the retention of P and long-term effects following application of FeCl3 (0.5–1 mol Fe/m2, 2010) in the eutrophic, shallow peat lake Terra Nova (the Netherlands). Treatment reduced P levels in the lake for two years, but afterwards summer release of P intensified, resulting in higher surface water P concentrations than before treatment. Porewater and sediment analyses indicate that the majority of the added Fe is still undergoing redox cycling within the top 10 cm of sediment accounting for the binding of up to 70 \% of sedimentary P. Sequential extractions further suggest that organic matter (OM) plays a key role in the resulting P and Fe dynamics: While reduction of P binding Fe(III) phases results in P release to porewaters, the produced Fe2+ remains bound to the solid phase presumably stabilized by OM. This causes P release from the sediments in excess to Fe during temporary low oxygen conditions in summer months, as confirmed by whole core flux incubation experiments. Quantitative coprecipitation of P with Fe upon reoxygenation of the water body is then impossible, leading to a gradual increase in surface water P. This first long-term study on a shallow peat lake underpins the role of OM for Fe cycling and the need to carefully consider the sediment properties and diagenetic pathways in the planning of Fe-amendments.",

keywords = "Internal phosphorus loading, Iron treatment, Lake restoration, Sediment geochemistry, Shallow peat lake",

author = "M{\"u}nch, \{Melanie A.\} and \{van Kaam\}, Rianne and Karel As and Stefan Peiffer and Heerdt, \{Gerard ter\} and Slomp, \{Caroline P.\} and Thilo Behrends",

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T1 - Impact of iron addition on phosphorus dynamics in sediments of a shallow peat lake 10 years after treatment

AU - Münch, Melanie A.

AU - van Kaam, Rianne

AU - As, Karel

AU - Peiffer, Stefan

AU - Heerdt, Gerard ter

AU - Slomp, Caroline P.

AU - Behrends, Thilo

PY - 2024/1/1

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N2 - Internal phosphorus (P) loading is a key water quality challenge for shallow lakes. Addition of iron (Fe) salts has been used to enhance P retention in lake sediments. However, its effects on sediment geochemistry are poorly studied, albeit pivotal for remediation success. Here, we assess the factors controlling the retention of P and long-term effects following application of FeCl3 (0.5–1 mol Fe/m2, 2010) in the eutrophic, shallow peat lake Terra Nova (the Netherlands). Treatment reduced P levels in the lake for two years, but afterwards summer release of P intensified, resulting in higher surface water P concentrations than before treatment. Porewater and sediment analyses indicate that the majority of the added Fe is still undergoing redox cycling within the top 10 cm of sediment accounting for the binding of up to 70 % of sedimentary P. Sequential extractions further suggest that organic matter (OM) plays a key role in the resulting P and Fe dynamics: While reduction of P binding Fe(III) phases results in P release to porewaters, the produced Fe2+ remains bound to the solid phase presumably stabilized by OM. This causes P release from the sediments in excess to Fe during temporary low oxygen conditions in summer months, as confirmed by whole core flux incubation experiments. Quantitative coprecipitation of P with Fe upon reoxygenation of the water body is then impossible, leading to a gradual increase in surface water P. This first long-term study on a shallow peat lake underpins the role of OM for Fe cycling and the need to carefully consider the sediment properties and diagenetic pathways in the planning of Fe-amendments.

AB - Internal phosphorus (P) loading is a key water quality challenge for shallow lakes. Addition of iron (Fe) salts has been used to enhance P retention in lake sediments. However, its effects on sediment geochemistry are poorly studied, albeit pivotal for remediation success. Here, we assess the factors controlling the retention of P and long-term effects following application of FeCl3 (0.5–1 mol Fe/m2, 2010) in the eutrophic, shallow peat lake Terra Nova (the Netherlands). Treatment reduced P levels in the lake for two years, but afterwards summer release of P intensified, resulting in higher surface water P concentrations than before treatment. Porewater and sediment analyses indicate that the majority of the added Fe is still undergoing redox cycling within the top 10 cm of sediment accounting for the binding of up to 70 % of sedimentary P. Sequential extractions further suggest that organic matter (OM) plays a key role in the resulting P and Fe dynamics: While reduction of P binding Fe(III) phases results in P release to porewaters, the produced Fe2+ remains bound to the solid phase presumably stabilized by OM. This causes P release from the sediments in excess to Fe during temporary low oxygen conditions in summer months, as confirmed by whole core flux incubation experiments. Quantitative coprecipitation of P with Fe upon reoxygenation of the water body is then impossible, leading to a gradual increase in surface water P. This first long-term study on a shallow peat lake underpins the role of OM for Fe cycling and the need to carefully consider the sediment properties and diagenetic pathways in the planning of Fe-amendments.

KW - Internal phosphorus loading

KW - Iron treatment

KW - Lake restoration

KW - Sediment geochemistry

KW - Shallow peat lake

UR - https://www.scopus.com/pages/publications/85178066301

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DO - 10.1016/j.watres.2023.120844

M3 - Article

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SN - 0043-1354

VL - 248

JO - Water Research

JF - Water Research

M1 - 120844

ER -

Impact of iron addition on phosphorus dynamics in sediments of a shallow peat lake 10 years after treatment

Abstract

Bibliographical note

Funding

Keywords

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