Anaerobic oxidation of methane and its impact on iron and phosphorus cycling in marine sediments

206 Pages·2016·23.63 MB·English

Utrecht Studies in Earth Sciences No. 113
Anaerobic oxidation of methane and its
impact on iron and phosphorus cycling
in marine sediments
Matthias Egger
Utrecht 2016
ISBN 978-90-393-6614-1
ISSN 2211-4335
USES No. 113
Cover: Sunset over the Stockholm archipelago, Baltic Sea (June 2016), photo by Silke Severmann
Copyright © 2016 Matthias Egger
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Anaerobic oxidation of methane and its impact
on iron and phosphorus cycling
in marine sediments
Anaërobe oxidatie van methaan en de gevolgen
voor de ijzer en fosfor kringlopen
in mariene sedimenten
(met een samenvatting in het Nederlands)
Anaerobe Methanoxidation und deren Einfluss
auf den Eisen- und Phosphorkreislauf
in marinen Sedimenten
(mit einer Zusammenfassung in deutscher Sprache)
Proefschrift
te verkrijging van de graad van doctor aan de Universiteit Utrecht
op gezag van de rector magnificus, prof. dr. G. J. van der Zwaan,
ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op
vrijdag 9 september 2016 des middags te 2.30 uur
door
Matthias Jürg Egger
geboren op 1 januari 1987 te St. Gallen, Zwitserland
Promotor:
Prof. dr. ir. Caroline P. Slomp
Members of the dissertation committee:
Prof. dr. Jack J. Middelburg
Utrecht University
The Netherlands
Prof. dr. Gert J. de Lange
Utrecht University
The Netherlands
Prof. dr. Klaus Wallmann
GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
Germany
Prof. dr. Bo Thamdrup
University of Southern Denmark
Denmark
PD. dr. Sabine Kasten
Alfred-Wegener Institut
Germany
Für meine Eltern,
Doubt is not a pleasant condition, but certainty is absurd.
- Voltaire
Contents
Abstract 9
Chapter 1 General introduction and thesis outline 11
Chapter 2 Iron-mediated anaerobic oxidation of methane in brackish coastal 21
sediments
Matthias Egger, Olivia Rasigraf, Célia J. Sapart, Tom Jilbert, Mike S. M. Jetten,
Thomas Röckmann, Carina van der Veen, Narcisa Bândă, Boran Kartal,
Katharina F. Ettwig and Caroline P. Slomp
Environ. Sci. Technol. (2015); doi:10.1021/es503663z
Chapter 3 Iron-dependent anaerobic oxidation of methane in coastal surface 37
sediments: potential controls and impact
J urjen Rooze, Matthias Egger, Iana Tsandev and Caroline P. Slomp
Limnol. Oceanogr. (2016); doi: 10.1002/lno.10275
Chapter 4 Vivianite is a major sink for phosphorus in methanogenic coastal surface 59
sediments
Matthias Egger, Tom Jilbert, Thilo Behrends, Camille Rivard and Caroline P. Slomp
Geochim. Cosmochim. Acta (2015); doi: 10.1016/j.gca.2015.09.012
Chapter 5 Anaerobic oxidation of methane alters sediment records of sulfur, iron and 91
phosphorus in the Black Sea
Matthias Egger, Peter Kraal, Tom Jilbert, Fatimah Sulu-Gambari, Célia J. Sapart,
Thomas Röckmann and Caroline P. Slomp
Biogeosciences Discuss. (2016); doi: 10.5194/bg-2016-64 (revised for Biogeosciences)
Chapter 6 Iron oxide reduction in deep Baltic Sea sediments: the potential role of 127
anaerobic oxidation of methane
Matthias Egger, Mathilde Hagens, Célia J. Sapart, Nikki Dijkstra,
Niels A. G. M. van Helmond, José Mogollón, Nils Risgaard-Petersen, Sabine Kasten,
Natascha Riedinger, Michael E. Böttcher, Carina van der Veen, Thomas Röckmann,
Bo Barker Jørgensen and Caroline P. Slomp
(to be submitted)
Chapter 7 Rapid sediment accumulation results in high methane effluxes from coastal 153
sediments
Matthias Egger, Wytze Lenstra, Dirk Jong, Filip J. R. Meysman, Célia J. Sapart,
Carina van der Veen, Thomas Röckmann, Santiago Gonzalez and Caroline P. Slomp
PlosONE (accepted in revised form)
References 177
Samenvatting (Summary in Dutch) 193
Zusammenfassung (Summary in German) 197
Acknowledgments (Danksagung) 201
Curriculum Vitae 204
List of publications 205
Abstract
Methane (CH) represents one of the key compounds in the global carbon (C) cycle. A major
4
part of the CH in the Earth system is produced in marine sediments by methanogenesis, the
4
final step in the gradual fermentation of organic matter deposited on the seafloor. Once emitted
to the atmosphere, CH acts as a powerful greenhouse gas. Despite high rates of methanogenesis
4
in continental shelf and slope environments, the ocean today contributes only a relatively small
amount of this potent greenhouse gas to the global atmospheric budget. The low atmospheric CH
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efflux from the ocean is largely due to the effective biological removal of dissolved CH through
4
anaerobic oxidation with sulfate (SO2-) in marine sediments. This removal of pore water CH
4 4
occurs within a distinct sulfate/methane transition zone (SMTZ), preventing the large amounts of
CH generated in marine sediments from escaping to the water column. The relevant pathways and
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the environmental factors that control the rates of CH oxidation in marine sediments are, however,
4
still incompletely understood. In some settings, for example, pore water CH is found throughout
4
the SO2- bearing zone, pointing towards an inefficient CH oxidation by SO2- in certain marine
4 4 4
environments. Other more recent findings further indicate that nitrate and nitrite, as well as metal
oxides (e.g. manganese and iron (Fe) oxides) can enhance the conversion of CH to CO in the
4 2
absence of oxygen. Sulfate may thus not be the only electron acceptor used by microorganisms
to oxidize CH in anoxic sediments, but knowledge about the significance of additional electron
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acceptors for the global CH cycle is still lacking. In addition, little is known about how CH
4 4
oxidation may impact the marine cycling of Fe and phosphorus (P), both key nutrients for oceanic
phytoplankton.
This thesis aims to refine our understanding of the potential impacts and controls of CH
4
oxidation in marine sediments. In particular, it discusses how anaerobic oxidation of CH affects
4
the sequestration and sedimentary records of Fe and P, using a wide range of geochemical tools.
The results presented here also demonstrate that climate change and anthropogenic nutrient loading
may alter the position and efficiency of the CH oxidation barrier in coastal sediments, which in
4
turn could lead to increased atmospheric CH emissions from the coastal ocean.
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Baltic Sea
Photo: Silke Severmann