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Noble gases trapped in the pore fluids of aquatic sediments as environmental tracers

English title Noble gases trapped in the pore fluids of aquatic sediments as environmental tracers
Applicant Kipfer Rolf
Number 162447
Funding scheme Project funding
Research institution Wasserressourcen und Trinkwasser Eawag
Institution of higher education Swiss Federal Institute of Aquatic Science and Technology - EAWAG
Main discipline Hydrology, Limnology, Glaciology
Start/End 01.10.2016 - 30.09.2020
Approved amount 333'604.00
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All Disciplines (6)

Discipline
Hydrology, Limnology, Glaciology
Other disciplines of Physics
Oceanography
Other disciplines of Environmental Sciences
Geophysics
Geochemistry

Keywords (6)

aquifer-aquitard-exchange; reconstruction of past enviromental conditions; glacial clays/aquitards; noble gas geochemistry; pore water residence time; pore fluids

Lay Summary (German)

Lead
Edelgase in Porenfluiden von aquatischen Sedimenten als Umwelttracer
Lay summary

Edelgase werden erfolgreich im Grundwasser eingesetzt, um Wasseraufenthaltszeiten und vergangene Klima- und Umweltbedingungen zu bestimmen. Seit Kurzem ist es möglich, Edelgase im Porenwasser von unkonsolidierten Sedimenten zu analysieren, um daraus die physikalischen Bedingungen im überliegenden See oder Meer zu analysieren. Ziel dieser Dissertationsarbeit ist es, die erwähnten Methoden und Ansätze zu verbinden, damit sich neu auch Porenwässer in schlechtdurchlässigen Gefügen und Gesteinen studieren lassen (Module A-C).

A In Schweizer Seen finden sich Tone, deren Ablagerung mit dem Gletscherrückzug nach der letzten Eiszeit in Verbindung gebracht werden. Hypothesen zur Bildung der Tone nehmen an, dass nach dem Rückzug der Gletscher entweder Flüsse feinstes Material in einen neuen See eintrugen oder dass die Tonablagerung in Zusammenhang mit 'vor Ort' schmelzendem Toteis steht. Je nach Ablagerungsbedingungen sind in den Porenwässer der Tone klar unterschiedliche Edelgaskonzentrationen zu erwarten, so dass sich daraus Rückschlüsse auf die Entstehung der Seen ziehen lassen.

B Der Austausch zwischen Aquiferen und Aquitarden bestimmt die chemische Zusammensetzung von alten Grundwasser. Ähnliches ist auch bei jungen Grundwässern zu vermuten, jedoch lässt sich dies bis anhin kaum experimentell nachweisen. Um die Stoffdynamik an Grenze zwischen Grundwasserleitern und -stauern in jungen Grundwässern zu studieren, werden wir Bohrkerne ziehen, um daraus wie in Seesedimenten Edelgase zu extrahieren, um Wasseraufenthaltszeiten und den Austausch zwischen Aquiferen und Aquitarden zu quantifizieren.

C Um die angesprochenen Fragestellungen angehen zu können, gilt es die analytischen Konzepte und Techniken so zu erweitern, dass neu auch Edelgasmessungen in schlechtdurchlässigen Sedimenten möglich werden. Hierzu werden wir die bestehenden Verfahren zur Edelgasbestimmung in Grundwässern und Sedimenten kombinieren.

Direct link to Lay Summary Last update: 10.08.2016

Lay Summary (English)

Lead
Noble gases trapped in the pore fluids of aquatic sediments as environmental tracers
Lay summary

The aim of the PhD research project is to combine the limnosedimentological and hydrogeological branches of environmental (noble) gas geochemistry. The focus of the project is to develop (noble) gas geochemistry of pore fluids in fine grained sediments/matrices as a tool to reconstruct palaeoenvironmental conditions (A) and the exchange of water and solutes at aquifer/aquitard interfaces (B), these studies will be complemented by expansions of our recently developed noble-gas analysis methods (C).

A - Analysis of noble gases in the glacial clays of lacustrine systems to investigate lake formation. We aim to study and reconstruct the palaeohydrological conditions that prevailed during deglaciation and formation of Swiss lake basins.

B - Determination of porewater residence times in aquitards to constrain solute & fluid exchange between aquifers and their confining aquitards. This module aims to analyze the exchange of dissolved gases between the pore fluids across the aquifer/aquitard interface in spatial ('coring' of aquifers) and temporal high resolution (GE-MIMS measurement in aquifers and aquitards).

C - Development of high-resolution dissolved-gas analysis techniques. We aim to adapt and to transfer our limnosedimentological techniques to aquifer/aquitard systems and vice versa.

The project targets to consolidate and expand the use of noble gas geochemistry as a widely applicable tool to study palaeoenvironmental conditions and processes as well as to analyze the transport of fluids and solutes in fine-grained sediments.

Direct link to Lay Summary Last update: 10.08.2016

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Noble gases in sediment pore water yield insights into hydrothermal fluid transport in the northern Guaymas Basin
Horstmann E., Tomonaga Y., Brennwald M.S., Schmidt M., Liebetrau V., Kipfer R. (2021), Noble gases in sediment pore water yield insights into hydrothermal fluid transport in the northern Guaymas Basin, in Marine Geology, 106419-106419.
On-line monitoring of the gas composition in the Full-scale Emplacement experiment at Mont Terri (Switzerland)
Tomonaga Yama, Giroud Niels, Brennwald Matthias S., Horstmann Edith, Diomidis Nikitas, Kipfer Rolf, Wersin Paul (2019), On-line monitoring of the gas composition in the Full-scale Emplacement experiment at Mont Terri (Switzerland), in Applied Geochemistry, 100, 234-243.

Collaboration

Group / person Country
Types of collaboration
Aquatic Physics, Institute F.-A. Forel, University Geneva (Prof. Dr. D. McGinnis) Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
GEOMAR (Dr. Mark Schmidt, Dr. Thor Hansteen), Kiel, Deutschland Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Sedimentology, SURF, Eawag (Dr. N. Dubois) Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
- Exchange of personnel
Hydrogeology, W+T, Eawag (Prof. Dr. M. Schirmer) Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Associated projects

Number Title Start Funding scheme
169911 Swiss membership in the International Scientific Continental Drilling Program ICDP 01.01.2017 Research Infrastructure
132155 Noble-gas and fluid transport processes in lake sediments 01.09.2011 Project funding
105263 Edelgase in Sedimenten als Indikatoren für Umweltveränderungen in Seen 01.10.2004 Project funding
124981 The Swiss contribution to the Lake Van Drilling Project: 500000 years of environmental and climate change in Eastern Anatolia (Science Part) 01.01.2010 Project funding
68191 Edelgase in Sedimenten als Indikation für Umweltveränderungen in Seen 01.10.2002 Project funding
109465 Noble gases as tracers for transport of solutes and fluids in lake sediments 01.10.2005 Project funding
143340 The Swiss contribution to the ICDP Lake Van Drilling Project: Linking modern seismic and biogeochemical signatures to 500,000 years of environmental history 01.01.2013 Project funding

Abstract

In the previous SNF projects, experimental techniques for the sampling and analysis of dissolved noble gases and CH4 in the pore water of lake sediments were developed. Numerous applications of these methods indicate that dissolved (noble) gases in sediment pore water are promising proxies for (palaeo)environmental conditions in surface waters, and for the transport of solutes in the sediment and their release into the overlying water body and into the atmosphere. An Eawag-funded PhD project developed an on-site mass spectrometer for continuous analysis (GE-MIMS) of dissolved noble gases and other biogeochemically active gases in groundwaters allowing to study and quantify the gas-exchange and transport of dissolved gases with respect to groundwater aeration and O2 turnover in real time in the field.The aim of the PhD research project proposed here is to combine the limnosedimentological and hydrogeologcal branches of environmental (noble) gas geochemistry. The focus of the project is to develop (noble) gas gecheistry of pore fluids in fine grained sediments/matrices as a tool to reconstruct palaeoenvironmental condtions (module A) and the exchange of water and solutes at aquifer/aquitard interfaces (module B), these studies will be complemented by expansions of our recently developed noble-gas analysis methods (module C).Module A - Analysis of noble gases in the glacial clays of lacustrine systems to investigate lake formation. We aim to study and reconstruct the palaeohydrological conditions that prevailed during deglaciation and formation of Swiss lake basins. To study the environmental conditions prevailing during the early stages of the develoment of the water masses of Lake Zurich and of Lake Lucerne, we intend to analyze the record of atmospheric noble gases in the pore water of the glacial sediments associated with the deglaciation and lake formation.Module B - Determination of porewater residence times in aquitards to constrain solute & fluid exchange between aquifers and their confining aquitards. The hydraulic ‘age’ of the bulk water rate is conceived to be lower than the 'age' derived from age tracer dissolved in the water, as solutes can be retarded due exchange with aquitards. To study this ‘paradox of groundwater age’ and to quantify the aquifer/aquitard exchange, we aim to analyze the exchange of dissolved gases between the pore fluids across the aquifer/aquitard interface in spatial ('coring' of aquifers) and temporal high resolution (GE-MIMS measurement in aquifers and aquitards).Module C - Development of high-resolution dissolved-gas analysis techniques. Especially modules B will employ our recently developed techniques for (noble) gas analysis in lacustrine sediments and in free-flowing groundwaters. However, further expansions of these techniques are necessary to obtain spatially well-defined groundwater samples, high-resolution time-series of dissolved gas concentrations in aquitards, and possibly even high-resolution gas concentration profiles in sediment cores. To this end we aim to transfer our limnosedimentological techniques to aquifer/aquitard systems and vice versa.Based on these three modules, we aim to consolidate and further expand the uses of noble gas geochemistry as a widely applicable tool to study palaeoenvironmental conditions and processes as well as the transport of fluids and solutes in fine-grained sediments. We expect that the further development of our specialized analytical tech-niques will allow other research groups to adopt these new methods, which will thus be of direct benefit to other research not covered by the current project.
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