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Understanding the oceanic cycling of trace metal micronutrients

English title Understanding the oceanic cycling of trace metal micronutrients
Applicant Vance Derek
Number 153087
Funding scheme Project funding (Div. I-III)
Research institution Institut für Geochemie und Petrologie ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geochemistry
Start/End 01.04.2014 - 30.09.2015
Approved amount 172'667.00
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All Disciplines (2)

Discipline
Geochemistry
Oceanography

Keywords (5)

nanoSIMS; nutrient cycling; ocean chemistry; isotopes; trace metals

Lay Summary (German)

Lead
Dieses Projekt untersucht und quantifiziert den Beitrag von Spurenmetallnährstoffen an der biologischen Pumpe, einem Prozess der die Aufnahme von atmosphärischen CO2 im Ozean entscheidend regelt. Dieser Prozess wird durch Aufnahme von gelöstem CO2 in die Zellen von marinen Algen in der euphotischen Zone, deren Sinken in die Tiefe, sowie deren dortige Zersetzung (Regenration) durch Bakterien und tierischer Respiration zu CO2 geregelt. Wir sind bestrebt neu entwickelte Isotopensysteme zu benutzen, um die Rolle von den für biologische Prozesse essenziellen Spurenmetallen für die biologische Pumpe zu verstehen. Dazu verwenden wir Unterschiede in den Isotopenzusammensetzungen, welche während der Aufnahme in Zellen und deren Regeneration entstehen, als Tracer. Speziell zielt dieses Forschungsprojekt darauf ab, Lücken in unserem Verständnis vom innerozeanischen Kreislauf, sowie dem Transfer von gelösten zum sedimentären Pool, dieser neuen Spurenmetallisotopensystemen zu schliessen.
Lay summary

Ziele des Forschungsprojekts:

Spurenmetelle sind ein wichtiger Bestandteil der marinen Umwelt, da diese Metalle häufig ein limitierender Faktor für die Algenproduktion sind, und somit den Austausch von atmosphärischem und marinem CO2 beeinflussen. Unser primäres Ziel ist es die bislang wenig verstandenen Prozesse, durch den die Metalle von den Algen aufgenommen werden oder durch bakterielle und tierische Respiration regeneriert werden, zu identifizieren und zu studieren. Die weithin bekannte extreme Erschöpfung des gelösten Pools des Elements Zink in der euphotischen Zone, zum Beispiel, wird allgemein der Aufnahme in Zellen zur Verwendung in Enzymen und Proteinen, Aufnahme in die Silikatschalen von kleinen Mikroben, wie Diatomeen, oder Adsorption an suspendierten Feststoffen, zugeschrieben. Nun ist es wichtig zu verstehen, welche dieser Prozesse besonders wichtig sind, da sie sich unterschiedlich auf die Geschwindigkeit der Wiederversorgung der euphotischen Zone mit Zink durch Aufstieg von nährstoffreichem Tiefenwasser auswirken. Die Prozesse sind häufig mit merklichen Veränderungen der Isotopenzusammensetzung verbunden, so dass wir ihren individuellen Einfluss auf den Zinkkreislauf mit Hilfe von Isotopen studieren können. Wir beginnen unsere Studie mit Analysen von Partikeln, welche aus dem rezenten Ozean beprobt wurden.

 

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts:

Es ist von grosser Bedeutung für die Menschheit die Rolle des Ozeans im Bezug auf atmosphärische CO2 Variationen zu verstehen. Dies ist nicht nur eine wichtige wissenschaftliche Fragestellung, denn für die Menschen ist es wichtig die Auswirkungen von ihren CO2 Emissionen auf die Atmosphäre zu verstehen und vorhersagen zu können. Die wissenschaftliche Arbeit von drei Jahrzehnten gibt zu erkennen, dass marine Spurenelemente diesen Prozess entscheidend beeinflussen. Allerdings sind die genauen Mechanismen dahinter bei weitem noch nicht zufriedenstellend verstanden.

Direct link to Lay Summary Last update: 02.04.2014

Responsible applicant and co-applicants

Employees

Publications

Publication
Copper isotope signatures in modern marine sediments
Little S., Vance D., McManus J., Severmann S., Lyons T. (2017), Copper isotope signatures in modern marine sediments, in Geochimica et Cosmochimica Acta, 212, 263-273.
Silicon and zinc biogeochemical cycles coupled through the Southern Ocean
Vance D., Little S., de Souza G., Khatiwala S., Lohan M., Middag R. (2017), Silicon and zinc biogeochemical cycles coupled through the Southern Ocean, in Nature Geoscience, 10, 202-206.
The isotope geochemistry of zinc and copper
Moynier F., Vance D., Fujii T., Savage P. (2017), The isotope geochemistry of zinc and copper, in Reviews in Mineralogy and Geochemistry, 82, 543-600.
Key role of continental margin sediments in the oceanic mass balance of Zn and Zn isotopes
Little S., Vance D., Lyons T.W., McManus J. (2016), Key role of continental margin sediments in the oceanic mass balance of Zn and Zn isotopes, in Geology, 44, 207-210.
Biogeochemical cycling of cadmium isotopes along a high-resolution section through the North Atlantic
Conway T.M., John S.G. (2015), Biogeochemical cycling of cadmium isotopes along a high-resolution section through the North Atlantic, in Geochimica et Cosmochimca Acta, 148, 269-283.
Constraints on soluble aerosol Fe flux to the Southern Ocean at the Last Glacial Maximum
Conway T.M., Wolff E.W., Rothlisberger R., Mulvaney R., Elderfield H.E. (2015), Constraints on soluble aerosol Fe flux to the Southern Ocean at the Last Glacial Maximum, in Nature Communications, 6, 7850.
Controls on trave metal authigenic enrichment in reducing sediments: insights from modern oxygen-deficient settings
Little S.H., Vance D., Lyons T.W., McManus J. (2015), Controls on trave metal authigenic enrichment in reducing sediments: insights from modern oxygen-deficient settings, in American Journal of Science, 316, 77-119.
GEOTRACES Intercomparison of Dissolved Trace Elements at the Bermuda Atlantic Time Series Station.
Middag R., Sefarian R., Conway T.M., John S.G., Bruland K.W., de Baar H.J.W. (2015), GEOTRACES Intercomparison of Dissolved Trace Elements at the Bermuda Atlantic Time Series Station., in Marine Chemistry, 177, 476-489.
Molecular controls on Cu and Zn isotopic fractionation in Fe-Mn crusts, reply to comment by Manceau and Nagy
Sherman D.M., Little S.H., Vance D. (2015), Molecular controls on Cu and Zn isotopic fractionation in Fe-Mn crusts, reply to comment by Manceau and Nagy, in Earth and Planetary Science letters, 411, 313-315.
The cycling of iron, zinc and cadmium in the North East Pacific Ocean - insights from stable isotopes
Conway T.M., John S.G. (2015), The cycling of iron, zinc and cadmium in the North East Pacific Ocean - insights from stable isotopes, in Geochimica et Cosmochimica Acta, 164, 262-283.
The isotopic signature and distribution of particulate iron in the North Atlantic Ocean
Revels B.N., Ohnemus D.C., Lam P.J., Conway T.M., John S.G. (2015), The isotopic signature and distribution of particulate iron in the North Atlantic Ocean, in Deep Sea Research II, 116, 321-331.
Amodern framework for the interpretation of 238U/235U studies in ancient redox
Andersen M.B., Romaniello S., Vance D., Little S.H., Herdman R., Lyons T.W. (2014), Amodern framework for the interpretation of 238U/235U studies in ancient redox, in Earth and Planetary Science Letters, 400, 184-194.
Molecular controls on Cu and Zn isotopic fractionation in Fe-Mn crusts
Little S.H., Sherman D.M., Vance D. (2014), Molecular controls on Cu and Zn isotopic fractionation in Fe-Mn crusts, in Earth and Planetary Science Letters, 396, 213-222.
Closing in on the marine 238U/235U budget
Andersen M.B., Vance D., Morford J.L., Bura-Nakic E., Breitenbach S.F.M., Och L., Closing in on the marine 238U/235U budget, in Chemical Geology.

Collaboration

Group / person Country
Types of collaboration
Institute for Marine and Coastal Sciences, Rutgers United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
University of Oxford Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Ruder Boskovic Institute Croatia (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Bigelow Laboratory for Ocean Sciences United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
National Oceanography Centre, Southampton Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Goldschmidt Conference Talk given at a conference The oceanic biogeochemical cycle of zinc and its isotopes: the dominance of diatoms and the Southern Ocean 17.08.2015 Prague, Czech Republic Little Susan H.; Vance Derek;
Goldschmidt Conference Talk given at a conference Using a Global Model to Evaluate Processes that Control the Oceanic Zn Distribution 17.08.2015 Prague, Czech Republic Conway Timothy Mark;
Goldschmidt Conference Talk given at a conference Shallow pore water iron isotope signatures spanning the depth of the South Atlantic Ocean 17.08.2015 Prague, Czech Republic Conway Timothy Mark;
Goldschmidt Conference Talk given at a conference Dissolved and particulate Cu isotopes in the South Atlantic 17.08.2015 Prague, Czech Republic Vance Derek; Little Susan H.;
Goldschmidt Conference Talk given at a conference Fe isotope ratios as a tracer for anthropogenic aerosol sources 16.08.2015 Prague, Czech Republic Conway Timothy Mark;
Black Sea post cruise meeting Talk given at a conference Zn and Ni isotopes in the Black Sea 04.04.2015 Den Haag, Netherlands Little Susan H.; Vance Derek;
Geochemistry Research in Progress Meeting Talk given at a conference Covariation of trace metal authigenic enrichment in reducing sediments 23.03.2015 Southampton, Great Britain and Northern Ireland Little Susan H.;
American Geophysical Union, Fall Meeting Talk given at a conference Zn and Ni isotope systematics in the Black Sea: a modern analogue for past ocean anoxia 19.12.2014 San Francisco, United States of America Little Susan H.; Vance Derek;
American Geophysical Union, Fall Meeting Poster The Oceanic Biogeochemical Cycle of Zinc and Its Isotopes 19.12.2014 San Francisco, United States of America Vance Derek; Little Susan H.;


Communication with the public

Communication Title Media Place Year
Media relations: print media, online media Tiny organisms with a massive impact International 2017

Awards

Title Year
Leverhulme Junior Research Fellowship 2015

Associated projects

Number Title Start Funding scheme
143262 The development and application of transition metal isotope systems in surface Earth geochemistry 01.10.2012 Project funding (Div. I-III)
165904 Metal isotope constraints on biosphere-environment interactions in Earth history 01.04.2016 Project funding (Div. I-III)

Abstract

The supply of nutrients to the euphotic zone of the oceans controls phytoplankton growth and, to a large extent, the partitioning of carbon between the atmosphere and the oceans. Though the biogeochemical cycling of the major nutrients (C, P, N, Si) has been an area of very active research for many years, our understanding of the oceanic cycling of another set of biologically-important elements, the trace metal micronutrients, is still in its infancy. It is becoming clear, however, that these trace metals limit, or co-limit, algal growth in key oceanic settings, and thus carbon partitioning between the surface ocean and atmosphere now and in the past. The supply of nutrients to the euphotic zone is controlled both by their whole ocean budgets, as well as their internal oceanic biogeochemical cycling. There are critical gaps in our understanding of both these aspects of the ocean chemistry of the trace metals. We propose two linked sub-projects that are aimed at a better understanding of the sources of trace metals to the oceans, their intra-oceanic cycling, and ultimately their outputs from the dissolved pool to sediment. We propose to use a variety of sample sets and tools, but key among the latter are the new isotopic systems of these elements.Sub-Project A: Emerging constraints on the oceanic budgets of trace metals, including the two that are the focus here (Zn and Ni), suggest that we do cannot currently be closed. A significant new constraint comes from isotopic data for these metals in the oceanic realm, a pursuit that the proponent’s lab has been leading. Particularly for Ni, but also for Zn, one likely solution to these budgetary problems is the existence of an as yet un-quantified sedimentary source. Scarce pore water data suggest that these metals are mobilised by reductive dissolution of Mn and Fe oxides, and that there is a diffusive benthic source to the deep ocean. A similar source is well known for Fe, and isotopic studies have been instrumental in both identifying it and quantifying its magnitude. In this sub-project we seek to quantify this source for Ni and Zn, and to measure its isotopic composition. We will do this through the collection and analysis of pore water and sediment samples from key redox settings, and use mass balance and Earth System models to scale up to a global flux.Sub-Project B: Though it is clear that both Zn and Ni are intensely cycled in the oceans by biology, we currently know very little about the exact process by which this occurs. For example, the extreme removal of Zn from the photic zone has been variously attributed to uptake into cells for enzymatic use, uptake into diatom opal, uptake onto extra-cellular organic material associated with diatoms, and passive scavenging onto marine biological particulates. The precise process controls the timescale on which these biologically-important metals are recycled back to the photic zone after re-mobilisation in the deep ocean, and the extent to which trace metals control carbon sequestration in the modern and past surface ocean. These processes are often associated with distinctive isotopic fractionations. New isotopic data for both Zn and Ni from the dissolved phase can identify and quantify these different pathways for biological uptake, and have led the proponent to new hypotheses for the oceanic cycling of trace metals in general. However, these hypotheses need to be tested. One crucial missing piece of information concerns the size and isotopic composition of different pools of metals within oceanic phytoplankton. We aim here to begin to undertake these tests through analysis of biological particulates from the modern ocean.
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