The lake as an iron sink - new insights on the role of iron speciation

Abstract

The solubility and behavior of iron (Fe) in natural waters is tightly linked to Fe speciation, and Fe speciation likely influences how Fe distributes between the water column and sediments. In this study, the function of a lake as an Fe sink, with focus on the role of Fe speciation, was assessed for Lake Bolmen in southern Sweden. We found that a large fraction of the Fe flowing in to the lake was efficiently lost by sedimentation in the lake basin. Fe in inflowing water was a mix of organically complexed mononuclear Fe, Fe-(oxy)hydroxides and Fe-bearing clays, while surface sediments were composed of Fe-(oxy)hydroxides, Fe-bearing clays, Fe-bearing silicates and Fe sulfides. The absence of organically complexed Fe in the surface sediments indicates that the lake is mainly a sink for minerogenic fractions. Furthermore, while lakes are considered to be sinks of Fe, it has been suggested that this function may be impaired by increasing precipitation and consequently shorter water residence time. In this study there were large within- and between-year variations in precipitation and Fe concentrations. However, rather than smaller Fe losses to the sediments during wet years, within-lake losses tended to be larger due to higher loading of Fe from the catchment. Thus, forecasted increases in precipitation may result in enhanced catchment export and Fe loading to lakes, and subsequently enhanced Fe sequestration in sediments.

• author: Björnerås, Caroline ; Persson, Per ; Weyhenmeyer, Gesa A. ; Hammarlund, Dan and Kritzberg, Emma S.
• organization: Division aquatic ecology; Microbial Ecology (research group); MEMEG; Centre for Environmental and Climate Science (CEC); Quaternary Sciences; Aquatic Ecology (research group)
• publishing date: 2021-12-05
• type: Contribution to journal
• publication status: published
• subject: Geochemistry; Water Engineering
• keywords: Browning, Iron biogeochemistry, Mass balance, Organic carbon, X-ray absorption spectroscopy
• in: Chemical Geology
• volume: 584
• article number: 120529
• publisher: Elsevier
• external identifiers: scopus:85115807769
• ISSN: 0009-2541
• DOI: 10.1016/j.chemgeo.2021.120529
• language: English
• LU publication?: yes
• additional info: Funding Information: Fe-(oxy)hydroxides (FeOOH) dominated in the sediments but was also a major and often dominant component in aqueous samples, e.g. in the lake water, throughout the sampling year. The similar Fe speciation between inflow and outflow samples, and the larger Fe-OM contribution in spring samples, was supported by the WT plots (Fig. S3). Moreover, the pre-edge analysis indicated that Fe(III) was the predominant oxidation state in both aqueous and sediment samples, with the exception of the sediment sample from 1.25 cm depth that contained a mixture of Fe(III) and Fe(II) (Fig. S4).This work was supported by the Swedish Research Council (grant number 2015-05450 to E.S.K and 2016-04561 to P.P), Formas (942-2015-14 to E.S.K), as well as The Knut and Alice Wallenberg Foundation (2013.0073 to P.P). Thanks to Britt-Marie Pott and Linda Parkefelt at Sydvatten AB, and to River Lagan Water Council, for providing water chemistry data for Lake Bolmen. We thank Martin ?kerlep for assistance in the field and Clemens Klante for valuable help with producing the map. We are also grateful to Handong Yang at the Environmental Change Research Centre, University College London, for conducting the sediment dating and to Sofia Mebrahtu Wis?n at the Stable Isotope Service Lab, Department of Biology, Lund University, for assistance with chemical analyses. Synchrotron work was conducted at beamline line 4-1 at the Stanford Synchrotron Radiation Lightsource (SSRL), California, USA. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research, and by the National Institutes of Health, National Institute of General Medical Sciences (including P41GM103393). The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official views of NIGMS or NIH. Funding Information: This work was supported by the Swedish Research Council (grant number 2015-05450 to E.S.K and 2016-04561 to P.P), Formas ( 942-2015-14 to E.S.K), as well as The Knut and Alice Wallenberg Foundation ( 2013.0073 to P.P). Thanks to Britt-Marie Pott and Linda Parkefelt at Sydvatten AB, and to River Lagan Water Council, for providing water chemistry data for Lake Bolmen. We thank Martin Škerlep for assistance in the field and Clemens Klante for valuable help with producing the map. We are also grateful to Handong Yang at the Environmental Change Research Centre, University College London, for conducting the sediment dating and to Sofia Mebrahtu Wisén at the Stable Isotope Service Lab, Department of Biology, Lund University, for assistance with chemical analyses. Synchrotron work was conducted at beamline line 4-1 at the Stanford Synchrotron Radiation Lightsource (SSRL), California, USA. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science , Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515 . The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research , and by the National Institutes of Health , National Institute of General Medical Sciences (including P41GM103393 ). The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official views of NIGMS or NIH. Publisher Copyright: © 2021 Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
• id: 464f0abd-0920-46cd-912b-78e73d80a619
• date added to LUP: 2021-10-06 18:22:22
• date last changed: 2024-05-04 13:27:35