Near-surface Heating of Young Rift Sediment Causes Mass Production and Discharge of Reactive Dissolved Organic Matter.
Ocean margin sediments have been considered as important sources of dissolved organic carbon (DOC) to the deep ocean, yet the contribution from advective settings has just started to be acknowledged. Here we present evidence showing that near-surface heating of sediment in the Guaymas Basin, a young extensional depression, causes mass production and discharge of reactive dissolved organic matter (DOM). In the sediment heated up to ~100 °C, we found unexpectedly low DOC concentrations in the pore waters, reflecting the combined effect of thermal desorption and advective fluid flow. Heating experiments suggested DOC production to be a rapid, abiotic process with the DOC concentration increasing exponentially with temperature. The high proportions of total hydrolyzable amino acids and presence of chemical species affiliated with activated hydrocarbons, carbohydrates and peptides indicate high reactivity of the DOM. Model simulation suggests that at the local scale, near-surface heating of sediment creates short and massive DOC discharge events that elevate the bottom-water DOC concentration. Because of the heterogeneous distribution of high heat flow areas, the expulsion of reactive DOM is spotty at any given time. We conclude that hydrothermal heating of young rift sediments alter deep-ocean budgets of bioavailable DOM, creating organic-rich habitats for benthic life.
MARUM Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.|Department of Oceanography, National Sun Yat-Sen University, 80424 Kaohsiung, Taiwan.
Yu-Shih
YS
Lin
MARUM Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.|Alfred-Wegener-Institut Helmholtz Zentrum für Polar und Meeresforschung, Am Handelshafen 12, D-27570 Bremerhaven, Germany.
Boris P
BP
Koch
MARUM Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.
Tomas
T
Feseker
Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, 27599 NC, USA.
Kai
K
Ziervogel
MARUM Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.|Leibniz Institute of Freshwater Ecology and Inland Fisheries, 12587 Berlin, Germany.
Tobias
T
Goldhammer
MARUM Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.
Frauke
F
Schmidt
Bruker Daltonics GmbH, Bremen, Germany.
Matthias
M
Witt
MARUM Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.
Matthias Y
MY
Kellermann
MARUM Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.
Matthias
M
Zabel
Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, 27599 NC, USA.
Andreas
A
Teske
MARUM Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.
Kai-Uwe
KU
Hinrichs