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Life in Extreme Environments II: Carbon and Nitrogen Cycles in High Alkaline Systems

English title Life in Extreme Environments II: Carbon and Nitrogen Cycles in High Alkaline Systems
Applicant Bernasconi-Green Gretchen
Number 131922
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 01.10.2010 - 30.09.2012
Approved amount 241'979.00
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All Disciplines (2)

Discipline
Geochemistry
Other disciplines of Earth Sciences

Keywords (14)

Lost City; hydrothermal systems; serpentinization; carbonate precipitation; volatiles; organic geochemistry; stable isotopes; radiocarbon; compound-specific isotopes; lipid biomarkers; carbon; nitrogen; microbial activity; deep biosphere

Lay Summary (English)

Lead
Lay summary
This project is an organic geochemical and stable isotope study of modern serpentinite-carbonate systems, focused on understanding geochemical and microbial processes associated with the formation of high alkaline fluids during serpentinization. We compare two modern serpentinite-carbonate systems: the active marine Lost City hydrothermal system (MAR 30°N) and the land based alkaline springs in the Voltri Massif (Liguria, N. Italy). Our study builds on an immense set of data from the peridotite-hosted Lost City hydrothermal system, produced in collaboration with an international team of scientists over the past nine years. Lost City is unlike all other hydrothermal known to date and is characterized by metal- and CO2-poor, high pH fluids (9-11) with elevated hydrogen and methane contents resulting from serpentinization processes at depth. Similar processes occur in the ophiolites of Liguria, Italy, where fluids originating from deep aquifers circulate through variably serpentinized peridotites, resulting in Mg-rich to Ca- or Na-rich, high pH (10 - 12) waters, with elevated hydrogen and methane concentrations. We specifically aim to link inorganic reactions in the ultramafic basement rocks (i.e. serpentinization reactions) to microbial activity by characterizing the cycling of carbon and nitrogen in these high pH systems. Elucidating the sources of carbon to these systems is of particular interest as small organic compounds are hypothesized to form abiologically under conditions similar to those found in the subsurface of these two sites. Field and laboratory studies are designed to (1) determine if the high concentrations of the small organic acid, formate, found at Lost City is abiologically formed and if it is a common feature of serpentinization processes; (2) identify the primary carbon sources to microbial communities and determine if these compounds are the result of serpentinization reactions (CH4, formate); (3) determine if amino acids also form abiologically at Lost City and/or Liguria; (4) investigate the role of nitrogen fixation at these locations; and (5) identify the most energetically favourable metabolic reactions available for chemolithoautotrophy in these environments.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Letter: H2/CH4 ratios cannot reliably distinguish abiotic vs. biotic methane in natural hydrothermal systems
Lang Susan Q., Früh-Green Gretchen L., Bernasconi Stefano M., Lilley Marvin D., Proskurowski Giora, Reeves Eoghan P. (2012), Letter: H2/CH4 ratios cannot reliably distinguish abiotic vs. biotic methane in natural hydrothermal systems, in Proc. Natl. Acad. Sci. USA, 1-1.
Microbial Growth on Abiotic Carbon and Hydrogen in a Serpentinite-Hosted System
Lang Susan Q., Früh-Green Gretchen L., Bernasconi Stefano M., Lilley Marvin D., Proskurowski G., Méhay Sabine, Butterfield David A. (2012), Microbial Growth on Abiotic Carbon and Hydrogen in a Serpentinite-Hosted System, in Geochimimica et Cosmochim Acta, 92, 82-99.
Stable Isotope Analysis of Organic Carbon in Small (μg) Samples and Dissolved Organic Matter Using a GasBench Preparation Device
Lang Susan Q., Bernasconi Stefano M., Früh-Green Gretchen L. (2012), Stable Isotope Analysis of Organic Carbon in Small (μg) Samples and Dissolved Organic Matter Using a GasBench Preparation Device, in Rapid Communications in Mass Spectrometry, 26(1), 9-16.

Collaboration

Group / person Country
Types of collaboration
Matthew Schrenk United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
Marvin Lilley United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
David Butterfield United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Deborah Kelley United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
William Brazelton United States of America (North America)
- 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
Serpentine Days 02.09.2012 Porquerolles Island, France
Dark energy biosphere institute research coordination network meeting 07.06.2012 Bremen
The Deep-Sea & Sub-Seafloor Frontier Conference 12.03.2012 Stiges, Spain
AGU Fall Meeting 05.12.2011 San Francisco, California
International Meeting of Organic Geochemistry 18.09.2011 Interlaken, Switzerland
Goldschmidt Conference 14.08.2011 Prague
IODP/ICDP Workshop on the role of oceanic and continental scientific drilling 08.01.2011 Muscat, Oman
AGU Fall Meeting 06.12.2010 San Francisco, California


Associated projects

Number Title Start Funding scheme
134847 Compound-Specific Radiocarbon Analysis of Lake Sediments: A New Tool for Dating and Reconstruction of Carbon Dynamics of Soils Through the Holocene: part II 01.06.2011 Project funding (Div. I-III)
134947 Fluid-Rock Interaction and Fluid Fluxes in Mafic and Ultramafic Seafloor: Peridotite-hosted Hydrothermal Systems Past and Present 01.04.2011 Project funding (Div. I-III)
121840 Life in Extreme Environments: Carbon and Sulfur Organic Geochemistry of High Alkaline Systems 01.11.2008 Project funding (Div. I-III)
143891 Unravelling Abiotic and Biotic Sources and Sinks of Carbon in Marine Hydrothermal Systems 01.10.2012 Project funding (Div. I-III)
146886 Fluid-Rock Interaction and Fluid Fluxes in Mafic and Ultramafic Seafloor II: Peridotite-hosted Hydrothermal Systems Past and Present 01.04.2013 Project funding (Div. I-III)
163073 Drilling the Atlantis Massif (MAR 30°N) and the Samail ophiolite (Oman) 01.07.2016 Research Infrastructure
124669 Serpentinization, Fluids and Life II: Comparing Carbon and Sulflur Cycles in Modern and Ancient Environments 01.05.2009 Project funding (Div. I-III)
163187 Hydration and carbonation of mantle peridotite: Drilling the Atlantis Massif (MAR 30°N) and the Samail ophiolite (Oman) 01.01.2016 Project funding (Div. I-III)

Abstract

This project is a continuation of SNF project No. 200021-121840 (2008-2010) and builds on results of organic geochemical and stable isotope studies of geochemical and microbial processes associated with the formation of high alkaline fluids in two modern serpentinite-carbonate systems: the active marine Lost City hydrothermal system (MAR, 30°N), and modern high alkaline, Ca-OH springs associated with present-day serpentinization in the Voltri Massif (Liguria, N. Italy). Lost City is unlike all other hydrothermal known to date and is characterized by metal- and CO2-poor, high pH (9-11) fluids with elevated hydrogen and methane contents resulting from serpentinization processes at depth. Microbiological studies indicate that the alkaline 40-90°C fluids at Lost City support sulfur-oxidizing, sulfate-reducing, and methane-cycling microorganisms living within distinct domains of the hydrothermal chimneys and in the subsurface. An important finding of the integration of published genomic data and our preliminary results of molecular and isotopic characterization of the archaeal lipids is that the dominant phylotype of archaea in this system, the Lost City Methanosarcinales, can adapt to strong chemical gradients within a biofilm and may be capable of both methanogenesis and methanotrophy. The origin of carbon for methanogenesis and carbon cycling during fluid-rock-microbe interaction remain a conundrum in this CO2-limited system. In addition, genomic studies have identified a wide range of nitrogen fixation genes, suggesting that the Lost City Methanosarcinales may also have the ability to fix nitrogen from N2. In this follow-up study, we specifically address questions of the origin of formate and acetate in the Lost City fluids and their role as a methanogenic substrate. We also propose to conduct nitrogen isotope studies of organic nitrogen within the chimneys to test for active nitrogen fixation and to characterize the amino acids to elucidate nitrogen-cycling. A further aspect of our proposed study is to thermodynamically model metabolic reactions available for chemolithoautotrophy to compare the energy available for methanogenesis, methanotrophy, and sulfate reduction under alkaline conditions. Thus, our study will address the following questions: •Is the carbon source to the Lost City microbial communities mantle-derived (CH4, ?CO2, formate, acetate) or seawater-derived (DIC, carbonate chimneys)? •Is the abiological formation of formate a ubiquitous occurrence under conditions of serpentinization? •Is nitrogen fixation occurring at Lost City and/or Liguria? •Are amino acids abiologically formed during serpentinization processes? •What is the nature and fate of nitrogen cycling in highly alkaline serpentinizing environments? Is the biomass in Lost City chimneys fresh or degraded? •What are the most energetically favorable metabolic reactions available for chemolithoautotrophy under conditions similar to those at Lost City and Liguria?By comparing high pH serpentinite-carbonate systems in modern marine environments with those in modern meteoric environments, we will be able to evaluate the importance of abiotic versus biotic processes in the origin of organic compounds associated with serpentinization and to address the question as to whether Lost City is a good geological and bio-geochemical analogue for present-day serpentinization processes on land and in ancient marine systems.
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