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Mobility of trace metals in periodically flooded soils: Influence of reduced iron, manganese, and sulfur

English title Mobility of trace metals in periodically flooded soils: Influence of reduced iron, manganese, and sulfur
Applicant Kretzschmar Ruben
Number 156392
Funding scheme Project funding (Div. I-III)
Research institution Institut für Biogeochemie und Schadstoffdynamik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Pedology
Start/End 01.05.2015 - 30.04.2019
Approved amount 523'592.00
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All Disciplines (2)

Discipline
Pedology
Geochemistry

Keywords (10)

soil; oxidation; manganese; trace metals; iron ; nanoparticles; reduction; clay minerals; sulfides; riparian

Lay Summary (German)

Lead
Dieses Projekt untersucht die Dynamik von Spurenmetallen in Böden in Überflutungsgebieten. In Laborexperimenten werden Wassersättigung und Wiederbelüftung simuliert, um herauszufinden, wie Fe(II), Mn(II) und S(-II), das durch mikrobielle Reduktion während Wassersättigung gebildet wird, die Mobilität von Spurenmetallen beeinflusst.
Lay summary

Auenböden bilden die Schnittstelle zwischen aquatischen Ökosystemen und höher gelegenen terrestrischen Ökosystemen sowie zwischen Oberflächengewässern und Grundwasserkörpern. Der Transfer von Nähr- und Schadstoffen zwischen diesen Systemen wird durch den Weg durch die Auenböden reguliert. Daher kommt diesen Böden eine Schlüsselfunktion für die Erhaltung der Wasserqualität und die Stabilität von Ökosystemen zu. Überflutungsereignisse und wechselnde Grundwasserstände führen zu starken Veränderungen der Wassersättigung in Auenböden. Die damit verbundenen stark variierenden Redoxbedingungen wirken sich auf vielfältige Weise auf biogeochemische Prozesse einschliesslich des Kreislaufs von Spurenelementen aus. Ziel dieses Projekts ist es, zwei Kernpunkte der Dynamik von Spurenmetallen während Überflutung und Wiederbelüftung von Auenböden zu untersuchen: zum einen den Einfluss von Fe(II) und Mn(II) auf das Vermögen von Tonmineralen Spurenmetalle zu binden und zum andern die Mobilität und Stabilität von Spurenmetallsulfiden.

Die Ergebnisse dieses Projekts werden massgeblich dazu beitragen, die Mechanismen, welche die Mobilität von Spurenmetallen in Böden mit wechselnden Redoxbedingungen kontrollieren, besser zu verstehen und ferner helfen, die quantitative Beschreibung der Mobilität von Spurenmetallen in diesen Böden zu verbessern.


 

Direct link to Lay Summary Last update: 22.12.2014

Responsible applicant and co-applicants

Employees

Collaboration

Group / person Country
Types of collaboration
Prof. Andreas Kappler, University of Tübingen Germany (Europe)
- Publication
- Research Infrastructure
Dr. Ralf Kaegi, Eawag Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
IBP PhD Congress Talk given at a conference Influence of Mn(II) on the sorption of Cd(II) to clay minerals 26.04.2019 Dübendorf, Switzerland Van Groeningen Natacha; Kretzschmar Ruben; Christl Iso;
IBP PhD Congress 2019 Poster Effects of natural organic matter (NOM) on copper sulfide nanoparticle growth and stability 26.04.2019 Dübendorf, Switzerland Christl Iso; Hoffmann Kevin; Kretzschmar Ruben;
Swiss Geoscience Meeting Talk given at a conference Competitive sorption of Mn(II) and Cd(II) to clay minerals 01.12.2018 Bern, Switzerland Van Groeningen Natacha; Kretzschmar Ruben; Christl Iso;
IBP Congress 2018 Poster Sorption interactions between Cd(II) and Mn(II) on Fe-free montmorillonite under anoxic conditions 06.04.2018 Zurich, Switzerland Van Groeningen Natacha; Kretzschmar Ruben; Christl Iso;
IBP PhD Congress 2018 Poster Effect of metal-to-sulfide ratio, NOM, and Mn2+ on metal sulfide nanoparticle characteristics 06.04.2018 Zurich, Switzerland Kretzschmar Ruben; Hoffmann Kevin; Christl Iso;
Swiss Geoscience Meeting Poster Mn(II) and Cd(II) sorption to synthetic montmorillonite 18.11.2017 Davos, Switzerland Kretzschmar Ruben; Christl Iso; Van Groeningen Natacha;
Swiss Geoscience Meeting Poster Effect of metal-to-sulfide ratio, NOM, and Mn2+ on metal sulfide nanoparticle characteristics 18.11.2017 Davos, Switzerland Christl Iso; Hoffmann Kevin; Kretzschmar Ruben;


Awards

Title Year
Best Poster Award, IBP PhD Congress 2019

Associated projects

Number Title Start Funding scheme
170120 Reducing Cd and As uptake by rice in contaminated paddy soils: From biogeochemical processes to improved paddy management 01.08.2017 Bilateral programmes
138003 Redox-induced speciation changes and reductive mobilization of arsenic and iron in highly-contaminated river floodplains 01.01.2012 Project funding (Div. I-III)
135338 Influence of NOM on the dynamics of copper speciation in periodically flooded soils 01.04.2011 Project funding (Div. I-III)
117933 Dynamics of Trace Metal Speciation in Periodically Reduced Soils 01.03.2008 Project funding (Div. I-III)

Abstract

Riparian floodplain soils represent the interface between upland soils and aquatic ecosystems and between surface water and groundwater. Both nutrient and contaminant transfer between these systems is regulated by the passage through the riparian soils. Consequently, these soils have to be considered environmental key areas for water quality and ecosystem health. Flood events and variations in groundwater levels lead to strong variations in water-saturation resulting in highly variable redox conditions in riverine floodplain soils. These strong redox variations affect various biogeochemical processes including the cycling of trace metals. Due to their redox dynamics, riparian floodplain soils are distinctly different from aerobic upland soils or permanently reduced sediments. Based on current knowledge from studies on oxic upland soils and anoxic sediments trends in metal speciation under variable redox conditions may be inferred. But a detailed understanding of trace metal speciation in redox-dynamic environments is currently lacking due to the limited number of studies examining systems exhibiting varying redox conditions. Considering the current state of knowledge, two main issues have been identified to be elucidated in order to improve the understanding of trace metal dynamics in riverine floodplain soils:A) During periods of flooding, reductive dissolution of minerals leads to high concentrations of dissolved Fe2+ and Mn2+ in soil pore waters. The influence of dissolved Fe2+ and Mn2+ on trace metal binding to clay minerals is poorly known to date despite the fact that clay minerals represent major sorbents for cations in soils, especially under reducing conditions which impair the stability of iron (hydr-)oxides. Furthermore, the ability of clay minerals to form different types of surface complexes exhibiting strong differences in stabilities is expected to affect the fate of sorbed trace metals as well as sorbed Fe2+ and Mn2+ during re-aeration upon drainage of flood water. But no information is available on the effect of O2 exposure on co-sorbed Fe2+, Mn2+, and trace metals. We propose to investigate these processes in depth using a combination of macroscopic batch experiments, synchrotron spectroscopic techniques, and surface complexation modeling in order to provide a mechanistic and quantitative understanding of the observed processes.B) Once sulfate reducing conditions establish during extended periods of flooding, sulfide is generated being able to form sparingly soluble solids with trace metals such as e.g., Hg, Cu, and Cd. The formation of sulfides has been reported in recent literature. But it is still unclear, whether these trace metal-bearing phases are mobile. Considering the colloidal size of sulfide observed as well as the potential stability of sulfides against instantaneous re-oxidation in oxic runoff water, the sulfide formed in flooded soils are expected to contribute to contaminant transport from polluted floodplain soils. The mobility of nanoparticulate trace metal sulfides will be examined in controlled laboratory-scale transport experiments using synthetic sulfides and large soil column experiments in which flooding and drainage are simulated. Physicochemical characterization of the sulfide particles will help gain a profound understanding of trace metal sulfide mobility in transport. The proposed research will be carried out by two PhD students, each addressing one of the above described issues. PhD students will benefit from sharing their experience and expertise because of partial overlap of experimental techniques. Their results will greatly improve the mechanistic understanding of trace metal mobility in soils facing fluctuating redox conditions and help to develop quantitative models for assessing the mobility of trace metals in riverine floodplain soils.
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