Oxygen dynamics of marine sediments

Abstract

Benthic O₂ availability regulates many important biogeochemical processes and has crucial implications for the biology and ecology of benthic communities. Further, the benthic O₂ exchange rate represents the most widely used proxy for quantifying mineralization and primary production of marine sediments. Consequently, numerous researchers have investigated the benthic O₂ dynamics in a wide range of environments. On the basis of case studies – from abyssal sediments to microbial phototrophic communities – I hereby try to review the current status on what we know about controls that interrelate with the O₂ dynamics of marine sediments. This includes factors like: sedimentation rates, bottom water O₂ concentrations, diffusive boundary layers, fauna activity, light, temperature, and sediment permeability. The investigation of benthic O₂ dynamics represents a challenge in resolving variations on temporal and spatial scales covering several orders of magnitude. Such an effort requires the use of several complementary measuring techniques and modeling approaches. Recent technical developments (improved chamber approaches, O₂ optodes, eddy-correlation, benthic observatories) and advances in diagenetic modeling have facilitated our abilities to resolve and interpret benthic O₂ dynamics. However, all approaches have limitations and caveats that must be carefully evaluated during data interpretation. Much has been learned during the last decades but there are still many unanswered questions that need to be addressed in order to fully understand benthic O₂ dynamics and the role of sediments for marine carbon cycling.

Keywords:

• Benthic mineralization
• benthic photosynthesis
• biogeochemistry
• in situ
• lander technology
• microsensors
• planar optodes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

This manuscript is a shortened and revised version of the summary that was enclosed with my dissertation that was defended at the Faculty of Natural Sciences, University of Copenhagen on 26 June 2007 (the full thesis can be delivered from the secretariat of the faculty or from me). I would like to take this opportunity to thank many people: the defense-committee Kaj Sand-Jensen, Richard A. Jahnke and Clare E. Reimers for their efforts in evaluating my dissertation; thanks to the very many colleagues and co-authors with whom I have collaborated and to the very many TAs who have assisted me and helped me with all kinds of problems during my work; and thanks to my ‘mentors’ Bo Barker Jørgensen, Tom Fenchel and Niels Peter Revsbech, who all in their way have inspired me since I started as a student at the Department for Genetics and Ecology at Aarhus University. Thanks to Don Canfield, Tom Fenchel, Fillip Meysman and Jack Middelburg who all read and constructively commented upon the manuscript. Thanks to The Danish National Science Research Council, The Carlsberg Foundation, The European Commission and The Max Planck Society for financial support.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark