Deep-Ocean dissolved organic matter in hydrothermal vents


Oceanic dissolved organic carbon (DOC) is an important carbon pool, similar in magnitude to atmospheric CO2, but the fate of its oldest forms is not well understood (Dittmar and Stubbins, 2014; Hansell, 2013, doi:10.1146/annurev-marine-120710-100757). Hot hydrothermal circulation may facilitate the degradation of otherwise un-reactive dissolved organic matter, playing an important role in the long-term global carbon cycle. The oldest, most recalcitrant forms of DOC, which make up most of oceanic DOC, can be recovered by solid-phase extraction. Here we present measurements of solid-phase extractable DOC from samples collected between 2009 and 2013 at seven vent sites in the Atlantic, Pacific and Southern oceans, along with magnesium concentrations, a conservative tracer of water circulation through hydrothermal systems. We find that magnesium and solid-phase extractable DOC concentrations are correlated, suggesting that solid-phase extractable DOC is almost entirely lost from solution through mineralization or deposition during circulation through hydrothermal vents with fluid temperatures of 212-401 °C. In laboratory experiments, where we heated samples to 380 °C for four days, we found a similar removal efficiency. We conclude that thermal degradation alone can account for the loss of solid-phase extractable DOC in natural hydrothermal systems, and that its maximum lifetime is constrained by the timescale of hydrothermal cycling, at about 40 million years (Elderfield and Schultz, 1996, doi:10.1146/

Supplement to: Hawkes, Jeffrey A; Rossel, Pamela E; Stubbins, Aron; Butterfield, David A; Connelly, Douglas P; Achterberg, Eric Pieter; Koschinsky, Andrea; Chavagnac, Valerie; Hansen, Christian T; Bach, Wolfgang; Dittmar, Thorsten (2015): Efficient removal of recalcitrant deep-ocean dissolved organic matter during hydrothermal circulation. Nature Geoscience, 8(11), 856-860

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Creator Hawkes, Jeffrey A ORCID logo; Rossel, Pamela E ORCID logo; Stubbins, Aron ORCID logo; Butterfield, David A ORCID logo; Connelly, Douglas P ORCID logo; Achterberg, Eric Pieter; Koschinsky, Andrea ORCID logo; Chavagnac, Valerie; Hansen, Christian T ORCID logo; Bach, Wolfgang ORCID logo; Dittmar, Thorsten ORCID logo
Publisher PANGAEA
Publication Year 2015
Rights Creative Commons Attribution 3.0 Unported;
OpenAccess true
Resource Type Supplementary Dataset; Dataset
Format text/tab-separated-values
Size 4130 data points
Discipline Earth System Research
Spatial Coverage (-30.189W, -56.089S, 130.763E, 48.000N); Lost City Hydrothermal Field, Mid-Atlantic Ridge; tropical/subtropical North Atlantic; South Atlantic Ocean
Temporal Coverage Begin 2001-07-21T00:13:00Z
Temporal Coverage End 2011-07-31T05:22:00Z