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COMpound specific and PArticle Selective radiocarbon analysiS (COMPASS): Forging novel research directions

Applicant Wacker Lukas
Number 197303
Funding scheme Project funding (Div. I-III)
Research institution Labor für Ionenstrahlphysik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geochemistry
Start/End 01.10.2020 - 30.09.2024
Approved amount 614'368.00
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All Disciplines (2)

Discipline
Geochemistry
Geochronology

Keywords (6)

compound-specific; radiocarbon; flow cytometry; micro-sublimation; accelerator mass spectrometry; particle-selective

Lay Summary (German)

Lead
Mit der Entwicklung von zwei neuen Radiokarbon Analysemethoden soll der Kohlenstoff Kreislauf mit Fokus auf Verbindungen und Partikeln organischen Ursprungs untersucht werden.
Lay summary

Komponenten-Spezifische und Partikel-Selektive Radiokarbon Analysen mittels neuer Extraktions- und Purifizierungsmethoden

Radiokarbon (14C) ist ein für die Erdwissenschaften sehr bedeutendes Hilfsmittel, da es nicht nur für Altersbestimmungen genutzt werden kann, sondern auch für die Untersuchungen des Kohlenstoffkreislaufs (KK), wobei vor allem Analysen von heterogenen Gemischen verschiedener Verbindungen unterschiedlichen Ursprungs, und somit potentiell auch unterschiedlichem 14C Gehalts, durchgeführt werden. Ein vertieftes Verständnis des KK kann erlangt werden, wenn spezifische Verbindungen oder Kleinstpartikel bekannten Ursprungs auf 14C analysiert werden, was wegen fehlender Analysetechniken bisher kaum möglich ist. 

Aufgrund der sehr erfolgreichen Zusammenarbeit von zwei ETH Forschungsgruppen (Labor für Ionstrahl Physik und Gruppe für Biogeowissenschaften) konnte gezeigt werden, dass 14C Analysen an kleinsten Kohlenstoffmengen durchgeführt werden können. Darauf aufbauend wollen wir nun zwei neue analytische Methoden entwickeln, die 14C Anlysen von spezifischen Verbindungen respektive Kleinstpartikeln erlauben: 

  • Isolation spezifischer Verbindungen mittels chromatographischer Methoden (HPLC, GC) und Mikrosublimation.
  • Abtrennung von Kleinstpartikeln (Pollen, Coccolithen) mittels Durchflusszytometrie.

Exemplarisch werden die Methoden dann auf folgende Anwendungen angewandt:

  • Vergleich proxy-spezifischer 14C Chronologien in laminierten Sedimenten 
  • Altersbeziehung von verschiedenen Proxy-Trägern (Foraminiferen, Alkenone, Coccolithen) in Ozeansedimenten

Ziel der Arbeit ist, den Kohlenstoff Kreislauf mit Fokus auf Verbindungen und Partikeln organischen Ursprungs über die letzten 45 000 Jahre besser zu verstehen. 

Direct link to Lay Summary Last update: 29.09.2020

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Number Title Start Funding scheme
170761 Enabling new frontiers in radiocarbon and geochemical analysis 01.09.2017 R'EQUIP

Abstract

Radiocarbon (14C) is a powerful tool that has paved the way for major scientific breakthroughs in geochronological research and studies of the carbon cycle. Traditionally, 14C measurements on the former have focused on comparably large macrofossils (if available), while for the latter studies bulk phases (e.g., particulate or dissolved organic matter) of environmental samples have been analyzed, even though they may comprise organic carbon derived from various sources. The presence or admixture of pre-aged components in a sample and/or the lateral transport or reworking of sample material within a stratigraphic sequence may further complicate the interpretation of measured 14C. A more precise and detailed level of understanding of the 14C age can be achieved by analysing specific components from such heterogeneous mixtures, such as individual compounds or small organic or inorganic particles of well-defined origin, a challenge that has so far been hampered by analytical limitations, mainly due to the low availability of selected sample materials.A very fruitful collaboration between two ETH research groups (Laboratory of Ion Beam Physics and Biogeoscience Group) has previously demonstrated that even smallest amounts of carbon can be analysed precisely for 14C. A recently installed flow cytometer (FC) dedicated to particle sorting in geosciences and a new gas interface for microscale 14C analyses acquired within a SNF R’Equipe program now provide a unique research platform enabling, for the first time, 14C measurements of specific compounds and selected particle classes from the same sample. These analyses will shed new light on 14C variability among different components, and thus lead to better understanding of the role of organic matter transport and deposition within the carbon cycle. At the same time, these advances will allow for more secure 14C dating, which is the backbone for any paleo-climatic work covering the last 45’000 years. The proposed study will be undertaken within the scope of two PhD student projects involving implementation of two new analytical methodical approaches, compound-specific and particle-selective 14C analysis, for studies of the carbon cycle and paleo-climate research. In collaboration with an international team of scientists led by the PI, the following milestones shall be realized:•Implementation of robust analytical protocols for routine flow cytometric isolation of pollen, coccoliths and living/detrital particles (PhD #1)•Purification with micro-sublimation of specific compounds, namely lignin phenols, alkenones and amino acids, for 14C analysis. (PhD #2).•Applying 1H-NMR for the identification of extraneous carbon to guide its subsequent removal. (PhD #2)•Develop the first independent, proxy-specific 14C chronologies (macro-fossils, pollen, lignin phenols) for lacustrine sedimentary sequences. (PhD #1)•First 14C measurements on coccoliths isolated from marine sedimentary matrices. (PhD #1)•Investigation of age relationships between different surface ocean-derived proxy-carriers (foraminifera, alkenones, coccoliths). (PhD #1)•Influence of hydrodynamic processes on transport and sedimentation of particulate organic matter. (PhD #2)•Assessment of provenance and turnover time of living (phytoplankton) and detrital particulate matter in the aquatic environment. (PhD #2)These innovative instrumental developments and novel analytical protocols employing a FC and microsublimation for combined compound-specific and particle-selective 14C analysis will catalyze advances both in paleo-climate and carbon cycle studies.
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