Saved in:
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Dataset Open Access |
| Language: | en |
| Published: |
PANGAEA
2017
|
| Subjects: | |
| Online Access: | https://doi.org/10.1594/PANGAEA.874298 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1867167675289960448 |
|---|---|
| author | Gomez-Saez, Gonzalo V Niggemann, Jutta Dittmar, Thorsten Pohlabeln, Anika M Lang, Susan Q Noowong, Ann Pichler, Thomas Wörmer, Lars Bühring, Solveig I |
| author_facet | Gomez-Saez, Gonzalo V Niggemann, Jutta Dittmar, Thorsten Pohlabeln, Anika M Lang, Susan Q Noowong, Ann Pichler, Thomas Wörmer, Lars Bühring, Solveig I |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Shallow submarine hydrothermal systems are extreme environments with strong redox gradients at the interface of hot, reduced fluids and cold, oxygenated seawater. Hydrothermal fluids are often depleted in sulfate when compared to surrounding seawater and can contain high concentrations of hydrogen sulfide (H2S). It is well known that sulfur in its various oxidation states plays an important role in processing and transformation of organic matter. However, the formation and the reactivity of dissolved organic sulfur (DOS) in the water column at hydrothermal systems are so far not well understood. We investigated DOS dynamics and its relation to the physicochemical environment by studying the molecular composition of dissolved organic matter (DOM) in three contrasting shallow hydrothermal systems off Milos (Eastern Mediterranean), Dominica (Caribbean Sea) and Iceland (North Atlantic). We used ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to characterize the DOM on a molecular level. The molecular information was complemented with general geochemical data, quantitative dissolved organic carbon (DOC) and DOS analyses as well as isotopic measurements (d2H, d18O and F14C). In contrast to the predominantly meteoric fluids from Dominica and Iceland, hydrothermal fluids from Milos were mainly fed by recirculating seawater. The hydrothermal fluids from Milos were enriched in H2S and DOS, as indicated by high DOS/DOC ratios and by the fact that >90% of all assigned DOM formulas that were exclusively present in the fluids contained sulfur. In all three systems, DOS from hydrothermal fluids had on average lower O/C ratios (0.26?0.34) than surrounding surface seawater DOS (0.45?0.52), suggesting shallow hydrothermal systems as a source of reduced DOS, which will likely get oxidized upon contact with oxygenated seawater. Evaluation of hypothetical sulfurization reactions suggests DOM reduction and sulfurization during seawater recirculation in Milos seafloor. The four most effective potential sulfurization reactions were those exchanging an O atom by one S atom in the formula or the equivalent + H2S reaction, correspondingly exchanging H2O, H2 and/or O2 by a H2S molecule. Our study reveals novel insights into DOS dynamics in marine hydrothermal environments and provides a conceptual framework for molecular-scale mechanisms in organic sulfur geochemistry. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_874298 |
| institution | PANGAEA |
| language | en |
| publishDate | 2017 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Geochemistry and dissolved organic matter in marine shallow hydrothermal systems Gomez-Saez, Gonzalo V Niggemann, Jutta Dittmar, Thorsten Pohlabeln, Anika M Lang, Susan Q Noowong, Ann Pichler, Thomas Wörmer, Lars Bühring, Solveig I Center for Marine Environmental Sciences; MARUM Shallow submarine hydrothermal systems are extreme environments with strong redox gradients at the interface of hot, reduced fluids and cold, oxygenated seawater. Hydrothermal fluids are often depleted in sulfate when compared to surrounding seawater and can contain high concentrations of hydrogen sulfide (H2S). It is well known that sulfur in its various oxidation states plays an important role in processing and transformation of organic matter. However, the formation and the reactivity of dissolved organic sulfur (DOS) in the water column at hydrothermal systems are so far not well understood. We investigated DOS dynamics and its relation to the physicochemical environment by studying the molecular composition of dissolved organic matter (DOM) in three contrasting shallow hydrothermal systems off Milos (Eastern Mediterranean), Dominica (Caribbean Sea) and Iceland (North Atlantic). We used ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to characterize the DOM on a molecular level. The molecular information was complemented with general geochemical data, quantitative dissolved organic carbon (DOC) and DOS analyses as well as isotopic measurements (d2H, d18O and F14C). In contrast to the predominantly meteoric fluids from Dominica and Iceland, hydrothermal fluids from Milos were mainly fed by recirculating seawater. The hydrothermal fluids from Milos were enriched in H2S and DOS, as indicated by high DOS/DOC ratios and by the fact that >90% of all assigned DOM formulas that were exclusively present in the fluids contained sulfur. In all three systems, DOS from hydrothermal fluids had on average lower O/C ratios (0.26?0.34) than surrounding surface seawater DOS (0.45?0.52), suggesting shallow hydrothermal systems as a source of reduced DOS, which will likely get oxidized upon contact with oxygenated seawater. Evaluation of hypothetical sulfurization reactions suggests DOM reduction and sulfurization during seawater recirculation in Milos seafloor. The four most effective potential sulfurization reactions were those exchanging an O atom by one S atom in the formula or the equivalent + H2S reaction, correspondingly exchanging H2O, H2 and/or O2 by a H2S molecule. Our study reveals novel insights into DOS dynamics in marine hydrothermal environments and provides a conceptual framework for molecular-scale mechanisms in organic sulfur geochemistry. |
| title | Geochemistry and dissolved organic matter in marine shallow hydrothermal systems |
| topic | Center for Marine Environmental Sciences; MARUM |
| url | https://doi.org/10.1594/PANGAEA.874298 |