Compositions of dissolved organic matter in the ice-covered waters above the Aurora hydrothermal vent system, Gakkel Ridge, Arctic Ocean

[摘要] Hydrothermal vents modify and displace subsurfacedissolved organic matter (DOM) into the ocean. Once in the ocean, this DOMis transported together with elements, particles, dissolved gases andbiomass along with the neutrally buoyant plume layer. Considering the numberand extent of actively venting hydrothermal sites in the oceans, theircontribution to the oceanic DOM pool may be substantial. Here, we investigatethe dynamics of DOM in relation to hydrothermal venting and relatedprocesses at the as yet unexplored Aurora hydrothermal vent field within theultraslow-spreading Gakkel Ridge in the Arctic Ocean at 82.9 ∘  N.We examined the vertical distribution of DOM composition from sea ice todeep waters at six hydrocast stations distal to the active vent and itsneutrally buoyant plume layer. In comparison to background seawater, wefound that the DOM in waters directly affected by the hydrothermal plume wasmolecularly less diverse and 5 %–10 % lower in number of molecular formulasassociated with the molecular categories related to lipid and protein-likecompounds. On the other hand, samples that were not directly affected by theplume were chemically more diverse and had a higher percentage of chemicalformulas associated with the carbohydrate-like category. Our results suggestthat hydrothermal processes at Aurora may influence the DOM distribution inthe bathypelagic ocean by spreading more thermally and/or chemically inducedcompositions, while DOM compositions in epipelagic and mesopelagic layersare mainly governed by the microbial carbon pump dynamics and surface-ocean–sea-ice interactions.

[学科分类] 大气科学