| 1. |
- Konn, Cécile, 1981-, et al.
(författare)
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Detection of trace organic compounds by Stir Bar Sorptive Extraction: application to the evolution of the organic composition of hydrothermal fluids from the Rainbow site (36°N, Mid-Atlantic Ridge) over 3 years
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The question of the abiogenic oil has been discussed and hydrothermal reactions have been suggested to abiotically generate hydrocarbons. Besides, ultramafic-hosted hydrothermal systems have been regarded as favourable environment for the emergence of life. Therefore, it is of great importance to investigate the presence of organic compounds in hydrothermal fluids. However, because of the sampling difficulties, the complexity of the matrix, the numerous interferences and the assumed trace level concentrations; it was considered a real challenge. Here we show that Stir Bar Sorptive Extraction (SBSE) coupled to Thermal Desorption – Gas Chromatography – Mass Spectrometry (TD-GC-MS) can be successfully applied to analyses of volatile and semi-volatile organic compounds in hydrothermal fluids. The method exhibited excellent reproducibility and conditioned samples appeared to be really stable for up to 3 years. This innovative and versatile technique was used to study the fluids from the ultramafic-hosted hydrothermal field Rainbow located at 36°14’N on the Mid-Atlantic Ridge (MAR). Despite relative stability for mineral composition and gas content is observed, analyses of fluids samples from 2005, 2007 and 2008 revealed more distinct organic compositions. In addition, results suggest the similarity of the organic content of the fluids regardless of the sampling location within the field, which may indicates the presence of a single reaction zone and that no further chemical reactions occur while fluids are transported to the seafloor.
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| 2. |
- konn, cecile, et al.
(författare)
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Fluids from ultramafic-hosted hydrothermal systems of the Mid Atlantic Ridge - Organics and Life.
- 2007
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Ingår i: EGU general assembly.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- The process of serpentinisation at slow spreading ridges is due to the circulation of seawater in outcropping mantle rocks. The periodites of the mantle are altered via fluid-rocks interaction generating high CH4- and H2-concentrations in the water column. The likely abiogenic origin of the methane has been supported by the isotope-ratio values. This has lead to the idea of abiogenic formation of larger organic compounds such as hydrocarbons or key molecules for the origin of life issue. Furthermore, Fisher-Tropsh type reactions might be a likely pathway to the production of these organic. Both thermodynamics and laboratory work support this idea, whilst field data are currently studied. During the EXOMAR cruise conducted by IFREMER, France; hydrothermal fluids from the MAR have been collected at different hot vent sites presenting highly different features (high/low pH, ultramafic/basaltic petrology, etc.). Innovative and efficient techniques have been used to concentrate and extract compounds from the fluids. As such, SPE (Solid Phase Extraction)-GC-MS and SBSE (Stir Bar Sorptive Extraction)-TD (ThermalDesorption)-GC-MS analyses showed the presence of a whole range of organics in the fluids. Mainly hydrocarbons, but also oxygen- and nitrogen-compounds were clearly identified by comparison of recorded mass spectra with library data. In order to establish whether the compounds were biogenic or abiogenic, carbon isotopic ratio measurements have been performed at the Vrije Universiteit Brussel. The 13C values suggest a mix of abiogenic and biogenic carbon for a great majority of the molecules. However, preliminary results indicate a possible abiogenic origin for a few compounds.This first step allowed us to get an overview of the fluids composition. We are now focusing on specific compounds in an origin of life perspective. Much effort has been put since to optimise the sample conditioning method in order to separate and concentrate targeted compounds. New methods will be tested during the last SERPENTINE mission to be conducted by IFREMER, France. We are expecting especially better results on the fatty acids. We are hoping as well to detect some origin of life key-compounds. This work is carried out partly within the MoMARnet (Monitoring deep sea floor hydrothermal environments on the Mid-Atlantic Ridge: A Marie Curie Research Training network’) framework.
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| 3. |
- Konn, Cécile, et al.
(författare)
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Hydrocarbons and oxidized organic compounds in hydrothermal fluids from Rainbow and Lost City ultramafic-hosted vents
- 2009
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Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 258, s. 299-314
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Tidskriftsartikel (refereegranskat)abstract
- The first building blocks of life could be produced in ultramafic-hosted hydrothermal systems considering the large amounts of hydrogen and methane generated by serpentinisation and Fischer-Tropsch-Type synthesis, respectively, in those systems. The purpose of this study was to detect and characterise organic molecules in hydrothermal fluids from ultramafic-hosted hydrothermal systems in the Mid-Atlantic Ridge (MAR) region. During the EXOMAR cruise 2005, fluids from the Rainbow (36°14’N) and the Lost City (30°N) hydrothermal fields were collected and treated by Stir Bar Sorptive Extraction (SBSE) and Solid Phase Extraction (SPE). The extracts were analysed by Thermal Desorption - Gas Chromatography - Mass Spectrometry (TD-GC-MS) and GC-MS, respectively. Compared to nearby deep seawater, hydrothermal fluids were clearly enriched in organic compounds, with a more diverse spectrum of molecules. We observed a very similar range of organic compounds in fluids from both sites, with a dominance of aliphatic hydrocarbons (C9-C14), aromatic compounds (C6-C16) and carboxylic acids (C8-C18). The occurrence of these compounds is supported by other field studies on serpentinites and sulfide deposits. Literature on thermodynamic data and experimental work has suggested the possible abiogenic origin of hydrocarbons and organic acids. In addition, it has been shown elsewhere that catalytic reactions producing hydrocarbons likely occur at both Lost City and Rainbow hydrothermal fields as suggested by the evolution of δ13C with increasing C number for methane, ethane, propane and butane. In order to investigate the origin of the organic molecules in the fluids, compound-specific carbon isotope ratio measurements were performed on n-alkanes and carboxylic acids, for which the δ13C values were in the range of -46 to -20‰ (vs. V-PDB). These preliminary data did not allow conclusive support or rejection of an abiogenic origin of the compounds. Indeed, predicting δ13C signatures in hydrothermal systems is likely to be complicated, due to differences in source δ13C signatures (i.e., of the C building blocks), and a variety of, mostly unknown, fractionation steps which may occur along the synthesis pathways. In addition, even though a fraction of the compounds detected in the fluids is likely abiotically produced, a dominance of biogenic sources and/or processes might hide their characteristic signature.
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| 4. |
- konn, cecile, et al.
(författare)
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Organic compound occurrence in fluids from ultramafic-hosted hydrothermal systems of the Mid-Atlantic ridge: a consequence of H2 production?
- 2008
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Konferensbidrag (populärvet., debatt m.m.)abstract
- A characteristic phenomenon that occurs at slow spreading ridge, e.g. the Mid-Atlantic Ridge, is the formation of large faults, which at some place results in lifting up of the mantle rocks up to the ocean floor. Ultramafic-hosted hydrothermal systems are precisely located on these mantle outcrops, where circulation of seawater along the faults alters the periodites that mainly compose the mantle. The process known as serpentinisation results the production of a large amount of H2, which is a great source of energy for further chemical reactions such as methane and heavier hydrocarbons production. High concentration of CH4 detected in the water column above ultramafic-hosted hydrothermal fields has indeed been suggested to be the abiogenic product of a Fisher-Tropsh synthesis (3H2 + CO CH4 + H2O), which is supported by the carbon isotopic data. This has lead to the idea of abiogenic formation of larger organic compounds such as hydrocarbons or key molecules for the origin of life issue. Both thermodynamics and laboratory work support this idea, but field data have been lacking up to date. Our study will present results on the organic content of hydrothermal fluids from 6 ultramafic-hosted hydrothermal fields of the MAR. Fluids were collected at Rainbow, Lost City, Logachev I & II and Ashadze I & II during the EXOMAR and the SERPENTINE cruises conducted by IFREMER, France. Innovative and efficient techniques have been developed, used and improved to concentrate, isolate and extract compounds from the fluids by SPE (Solid Phase Extraction)-GC-MS. Organics were listed and all compounds present in deep seawater and blank experiments were discarded as considered contaminants. The remaining appeared to be mainly hydrocarbons and oxygen-bearing compounds that were clearly -identified by comparison of recorded mass spectra with library data.This work is carried out partly within the MoMARnet (Monitoring deep sea floor hydrothermal environments on the Mid-Atlantic Ridge: A Marie Curie Research Training network) framework.
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| 5. |
- konn, cecile, et al.
(författare)
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Organic geochemistry of fluids from 4 ultramafic-hosted hydrothermal systems of the Mid Atlantic Ridge.
- 2007
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Ingår i: Interridge Woods Hole Oceanographic Institute (WHOI) theoretical Institute.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Ultramafic-hosted hydrothermal sites are characterized by mantle outcrops. On the Mid-Atlantic ridge, the Eurasian and American plates are moving appart resulting in the oceanic crust to tear up and to let the mantle rocks outcrop. Circulation of seawater, along the faults, within the mantle alters the periodites via the serpentinisation process, which produces a large amount of H2. Notably, H2 is a great source of energy for further chemical reactions. Besides, a high CH4 concentration in the water column is associated with ultramafic hydrothermal activity. This methane has been suggested to be abiogenic and to be formed via a Fisher-Tropsh synthesis (3H2 + CO CH4 + H2O). The isotope-ratio values support the later hypothesis. This has lead to the idea of abiogenic formation of larger organic compounds such as hydrocarbons or key molecules for the origin of life issue. Both thermodynamics and laboratory work support this idea, but field data had not been studied yet. During the EXOMAR and the SERPENTINE cruises conducted by IFREMER, France; hydrothermal fluids from the MAR have been collected at different hot vent sites (Rainbow, Lost City, Logachev, Ashadze). Innovative and efficient techniques have been developed, used and improved to concentrate, isolate and extract compounds from the fluids by SPE (Solid Phase Extraction)-GC-MS and SBSE (Stir Bar Sorptive Extraction)-TD (ThermalDesorption)-GC-MS analyses. Mainly hydrocarbons, but also oxygen- and nitrogen-compounds were clearly -identified by comparison of recorded mass spectra with library data. As for the analysis process, a particular attention is now paid to carboxylic acids and hydrocarbons as well as volatiles (C1-C8).This work is carried out partly within the MoMARnet (Monitoring deep sea floor hydrothermal environments on the Mid-Atlantic Ridge: A Marie Curie Research Training network’) framework.
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| 6. |
- konn, cecile, et al.
(författare)
-
Organics in hydrothermal fluids from 4 ultramafic-hosted vents of the MAR. Results from the SERPENTINE cruise (2007).
- 2008
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Ingår i: EGU, Vienna.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Ultramafic-hosted hydrothermal sites are characterized by mantle outcrops. On the Mid-Atlantic ridge, the Eurasian and American plates are moving apart resulting in the oceanic crust to tear up and to let the mantle rocks outcrop. Circulation of seawater, along the faults, within the mantle alters the periodites via the serpentinisation process, which produces a large amount of H2. Notably, H2 is a great source of energy for further chemical reactions. Besides, a high CH4 concentration in the water column is associated with ultramafic hydrothermal activity. This methane has been suggested to be abiogenic and to be formed via a Fischer-Tropsch synthesis (3H2 + CO gives CH4 + H2O). The isotope-ratio values support the later hypothesis. This has lead to the idea of abiogenic formation of larger organic compounds such as hydrocarbons or key molecules for the origin of life issue. Both thermodynamics and laboratory work support this idea, but field data had not been studied yet.During the EXOMAR (2005), SERPENTINE (2007) and MoMARDREAMNAUT (2007) cruises conducted by IFREMER, France; hydrothermal fluids from the MAR have been collected at different hot vent sites (Rainbow, Lost City, Logatchev and Ashadze). Their geological settings vary, leading to largely different fluids features as for T, pH, Cl and H2S concentration. Innovative and efficient techniques have been developed, used and improved (IFREMER, Brest) to concentrate, isolate and extract organic compounds from the fluids: SPE (Solid Phase Extraction)-GC-MS. Mainly hydrocarbons (C8 to C18), carboxylic acids and methyl esters were clearly identified by comparison of recorded mass spectra with library data. δ13C values have been measured by GC-IRMS (VUB Brussels) and were in the range -20‰ to -45‰, which did not allow to conclusively support or reject an abiotic origin.This work is carried out partly within the MoMARnet (Monitoring deep sea floor hydrothermal environments on the Mid-Atlantic Ridge: A Marie Curie Research Training network) framework.
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| 7. |
- Konn, Cécile, et al.
(författare)
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Characterisation of dissolved organic compounds in hydrothermal fluids by stir bar sorption extraction – gas chromatography – mass spectrometry : Case study: the Rainbow field (36°N, Mid-Atlantic Ridge)
- 2012
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Ingår i: Geochemical Transactions. - : Springer Science and Business Media LLC. - 1467-4866. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- The analysis of the dissolved organic fraction of hydrothermal fluids has been considered a real challenge due to sampling difficulties, complexity of the matrix, numerous interferences and the assumed ppb concentration levels. The present study shows, in a qualitative approach, that Stir Bar Sorptive Extraction (SBSE) followed by Thermal Desorption – Gas Chromatography – Mass Spectrometry (TD-GC-MS) is suitable for extraction of small sample volumes and detection of a wide range of volatile and semivolatile organic compounds dissolved in hydrothermal fluids. In a case study, the technique was successfully applied to fluids from the Rainbow ultramafic-hosted hydrothermal field located at 36°14’N on the Mid-Atlantic Ridge (MAR). We show that n-alkanes, mono- and poly- aromatic hydrocarbons as well as fatty acids can be easily identified and their retention times determined. Our results demonstrate the excellent repeatability of the method as well as the possibility of storing stir bars for at least three years without significant changes in the composition of the recovered organic matter. A preliminary comparative investigation of the organic composition of the Rainbow fluids showed the great potential of the method to be used for assessing intrafield variations and carrying out time series studies. All together our results demonstrate that SBSE-TD-GC-MS analyses of hydrothermal fluids will make important contributions to the understanding of geochemical processes, geomicrobiological interactions and formation of mineral deposits
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| 8. |
- Konn, Cécile, 1981-, et al.
(författare)
-
Detection of trace concentrations of amino acid in aqueous solutions by Ion-pairing reversed-phase UPLC-ESI-QToF-MS: application to hydrothermal fluids
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Amino acids are the fundamental building blocks of proteins that are required for the initiation of living organism, therefore they are key compounds in the origin of life quest. The abiotic production of amino acids within ultramafic-hosted hydrothermal systems was suggested a few decades ago and is strongly supported by thermodynamic data and experimental work. However, field data were clearly lacking and thus investigation of amino acids in fluids from ultramafic-hosted hydrothermal systems was of major importance. Even though amino acids analysis have been carried out routinely for several decades in various field of application, none of the currently available methods appeared suitable for our purpose because of the complexity of the hydrothermal fluids matrix (salts, minerals, gases) and the extremely low concentrations of amino acids that were expected. We took up the challenge and here we describe a method to detect underivatized amino acids down to the sub-ppb level in aqueous matrix by ion-pairing reverse-phase Ultra-high Performance Liquid Chromatography - Electrospray Ionisation - Quadrupole Time of Flight - Mass Spectrometry (UPLC-ESI-QTOF-MS). Characterisation and separation of 10 chosen proteinogenic amino acids was achieved and excellent linearity in the response was obtained for all amino acids with correlation coefficient > 0.9921. This analytical method was successfully applied to natural hydrothermal fluid samples from ultramafic-hosted vents of the Mid-Atlantic Ridge region. Tryptophan and Phenylalanine were clearly evidenced in the fluids and concentrations of Leucine reached 15-55 ppt. We suggest that other amino acids are present in hydrothermal fluids but occur for the major part as metal and/or clay complexes and could not be detected using current approach. Finally, concentrations of amino acids measured in the deep seawater reference sample were in good agreement with generally accepted background level in the deep ocean.
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| 9. |
- Konn, Cécile, 1981-, et al.
(författare)
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New insight on the origin of organic compounds in fluids from ultramafic-hosted hydrothermal systems
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Hydrocarbons gases (C1-C4) as well as larger organic compounds were reported elsewhere in fluids from the Rainbow and the Lost City ultramafic-hosted hydrothermal fields. Whereas hydrocarbon gases are likely abiogenic (Fischer-Tropsch Type reaction), the origin of larger molecules remains unclear. Our ability to differentiate between biotic and abiotic sources of organic compounds in deep-sea hydrothermal systems may give clues to the understanding of organic geochemistry on the early Earth. Here, we report a series of experiments of hydrothermal degradation (40 MPa / 200, 350 and 450°C) of the piezophile archaea Pyrococcus abyssi biomass, which provides supporting lines of evidence of the abiogenic origin of saturated hydrocarbons as well as of the possible biogenic origin of alkylated aromatic hydrocarbons, Polycyclic Aromatic Hydrocarbons (PAH) and C12:0-C16:0 fatty acids in fluids from ultramafic-hosted hydrothermal systems.
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| 10. |
- Konn, Cécile, 1981-
(författare)
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Origin of organic compounds in fluids from ultramafic-hosted hydrothermal vents of the Mid-Atlantic Ridge
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Natural gas, primarily methane (CH4), is produced in substantial amounts in ultramafic-hosted hydrothermal systems. These systems could also generate oil (heavier hydrocarbons) and the first building blocks of life (prebiotic molecules). In the presence of iron bearing minerals, serpentinisation reactions generate H2. Subsequently, CH4 could be synthesised by Fischer-Tropsch Type (FTT) reaction (4H2 + CO2 → CH4 + 2H2O) which is an abiotic process. This has lead to the idea of abiotic formation of larger organic molecules. Both thermodynamics and laboratory work support this idea, yet field data have been lacking. This study focuses on determining the organic content of fluids from ultramafic-hosted hydrothermal systems from the Mid-Atlantic Ridge (MAR) and the origin of the compounds. Fluids were collected from the Lost City, Rainbow, Ashadze and Logatchev vent fields during the EXOMAR (2005), SERPENTINE (2007), MoMARDREAMnaut (2007) and MOMAR08-Leg2 (2008) cruises conducted by IFREMER, France. A SBSE-TD-GC-MS technique was developed and used to extract, concentrate, separate and identify compounds in the fluids. Hydrothermally derived compounds appeared to consist mainly of hydrocarbons and O-bearing molecules. In addition, some amino acids were detected in the fluids by ULPC-ESI-QToF-MS but their origin will need to be determined. The organic content of the Rainbow fluids did not show intra field variability unlike differences could be noted over the years. In order to address the question of the source of the molecules, compound specific carbon isotopic analyses were carried out and completed with a bacterial (Pyrococcus abyssi) hydrothermal degradation experiment. The δ13C data fall in the range of -40 to -30‰ (vs. V-PDB), but individual δ13C values preclude the identification of a biogenic or abiogenic origin of the compounds. The degradation experiment, however, suggests an abiogenic origin of a portion of saturated hydrocarbons whereas carboxylic acids would be biogenic, and aromatic compounds would be thermogenic.
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