Imprint of Kairei and Pelagia deep-sea hydrothermal systems (Indian Ocean) on marine dissolved organic matter

Only few studies exist that investigate the dynamics of deep-sea dissolved organic matter (DOM) derived from hydrothermal vents. In this study, we provide first insight into the molecular composition of DOM associated with Indian Ocean hydrothermal systems covering the full range from hot focussed endmem ber fluids over diffuse fluids to open ocean hydrothermal plumes and deep seawater. We combined geochemical analyses with molecular characterization of DOM using ultra-high resolution mass spectrometry (FT-ICR-MS). We studied two vent systems with fluids venting 0.38) indicated potential input of more reduced (O-poor) DOM compounds from the vents into the surrounding seawater, independently of the vent location and of whether the fluid has undergone phase separation. To test the importance of pure thermal degradation, we compared our samples to fluids subjected to abiotic thermal degradation under laboratory conditions and we observed that our natural samples largely differed ( 94% Bray Curtis dissimilarity) from the experimental ones, suggesting additional degradation processes of organic compounds at the Indian Ocean hydrothermal systems. (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study provides insight into the molecular composition of DOM associated with Indian Ocean hydrothermal systems, showing the potential input of more reduced DOM compounds from hydrothermal vents into surrounding seawater. The research suggests additional degradation processes of organic compounds at the Indian Ocean hydrothermal systems.