Dissolved organic carbon in ridge-axis and ridge-flank hydrothermal systems

Lang, Susan Q.; Butterfield, D. A.; Lilley, Marvin D.; Johnson, H. Paul; Hedges, John I.

doi:10.1016/j.gca.2006.04.031

Cited by 171 publications

(169 citation statements)

References 81 publications

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“…Although we assumed a similar reservoir age for the Southern Ocean and Atlantic Ocean DOM, this mechanism of upwelling and mixing of old waters could lead to a distinct subset of Southern Ocean DOM being "too old" and being represented by the SOUR compounds. Other sources of 14 C depleted carbon (hydrothermal vents : Lang et al, 2006;Pohlman et al, 2011;chemoautotrophy: McCarthy et al, 2011;Middelburg, 2011;black carbon: Dittmar and Koch, 2006), and advection processes (transport from marginal sediments: deep water formation: Hansell et al, 2002) may substantially increase the deep ocean abundance of some old compounds that eventually reach the Weddell Sea surface. Another explanation for the increased abundance of the SOUR compounds is that they are not as readily degradable by heterotrophs in the Southern Ocean compared to the East Atlantic.…”

Section: Doc In the Southern Ocean -Too Much Or Too Old?mentioning

confidence: 99%

“…The lowest calculated rates are so low, that abiotic removal mechanisms seem likely to determine the ultimate fate of these compounds. Adsorption to particles and subsequent removal from the water column (Druffel and Williams, 1990), pyrogenic transformation through hydrothermal systems (Lang et al, 2006) or diapycnal mixing into surface waters may determine the decay rates of this persistent DOM fraction.…”

Section: Chemical Information On the Most Persistent Dom: The Island mentioning

confidence: 99%

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Molecular transformation and degradation of refractory dissolved organic matter in the Atlantic and Southern Ocean

Lechtenfeld

Kattner

Flerus

et al. 2014

Geochimica et Cosmochimica Acta

278

259

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More than 90% of the global ocean dissolved organic carbon (DOC) is refractory, has an average age of 4000-6000 years and a lifespan from months to millennia. The fraction of dissolved organic matter (DOM) that is resistant to degradation is a long-term buffer in the global carbon cycle but its chemical composition, structure, and biochemical formation and degradation mechanisms are still unresolved. We have compiled the most comprehensive molecular dataset of 197 Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses from solid-phase extracted marine DOM covering two major oceans, the Atlantic sector of the Southern Ocean and the East Atlantic Ocean (ranging from 50°N to 70°S). Molecular trends and radiocarbon dating of 34 DOM samples (comprising D 14 C values from À229& to À495&) were combined to model an integrated degradation rate for bulk DOC resulting in a predicted age of >24 ka for the most persistent DOM fraction. First order kinetic degradation rates for 1557 mass peaks indicate that numerous DOM molecules cycle on timescales much longer than the turnover of the bulk DOC pool (estimated residence times of up to~100 ka) and the range of validity of radiocarbon dating. Changes in elemental composition were determined by assigning molecular formulae to the detected mass peaks. The combination of residence times with molecular information enabled modelling of the average elemental composition of the slowest degrading fraction of the DOM pool. In our dataset, a group of 361 molecular formulae represented the most stable composition in the oceanic environment ("island of stability"). These most persistent compounds encompass only a narrow range of the molecular elemental ratios H/C (average of 1.17 ± 0.13), and O/C (average of 0.52 ± 0.10) and molecular masses (360 ± 28 and 497 ± 51 Da). In the Weddell Sea DOC concentrations in the surface waters were low (46.3 ± 3.3 lM) while the organic radiocarbon was significantly more depleted than that of the East Atlantic, representing average surface water DOM ages of 4920 ± 180 a. These results are in accordance with a highly degraded DOM in the Weddell Sea surface water as also shown by the molecular degradation index I DEG obtained from FT-ICR MS data. Further, we identified 339 molecular formulae which probably contribute to an increased DOC concentration in the Southern Ocean and potentially reflect an accumulation or enhanced sequestration of refractory DOC in the Weddell Sea. These results will contribute to a better understanding of the persistent nature of marine DOM and its role as an oceanic carbon buffer in a changing climate.

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Section: Doc In the Southern Ocean -Too Much Or Too Old?mentioning

confidence: 99%

Section: Chemical Information On the Most Persistent Dom: The Island mentioning

confidence: 99%

Molecular transformation and degradation of refractory dissolved organic matter in the Atlantic and Southern Ocean

Lechtenfeld

Kattner

Flerus

et al. 2014

Geochimica et Cosmochimica Acta

278

259

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“…At the Endeavour ridge, greater than 95% of the C measured within the first 21 vertical meters of a buoyant hydrothermal plume was identified as having a near-bottom biological origin 19 . More recently, measurements of DOC at the Juan de Fuca ridge have demonstrated elevated concentrations in some biologically productive areas of diffuse venting 20 . Dissolved organic ligands present in non-buoyant hydrothermal plumes at the Mid-Atlantic Ridge have been found to stabilize Fe(iii) in solution (these complexes may represent 12-22% of the dissolved Fe in the deep ocean) 4 .…”

mentioning

confidence: 99%

Preservation of iron(II) by carbon-rich matrices in a hydrothermal plume

et al. 2009

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. Here we present spectromicroscopic measurements of iron and carbon in hydrothermal plume particles at the East Pacific Rise mid-ocean ridge. We show that organic carbon-rich matrices, containing evenly dispersed iron(II)-rich materials, are pervasive in hydrothermal plume particles. The absence of discrete iron(II) particles suggests that the carbon and iron associate through sorption or complexation. We suggest that these carbon matrices stabilize iron(II) released from hydrothermal vents in the region, preventing its oxidation and/or precipitation as insoluble minerals. Our findings have implications for deep-sea biogeochemical cycling of iron, a widely recognized limiting nutrient in the oceans.The mixing of hot, chemically reduced hydrothermal fluids with cold, oxygenated deep-sea water drives the dominant inorganic reactions of polymetallic sulphide precipitation and Fe oxidation and precipitation in plumes 6 . As a consequence of seawater entrainment into rising plumes, the entire volume of the global ocean must, on average, come into contact with hydrothermal fluids and particles in a relatively short time, 4000-8000 yr. Much of the trace element chemical reactivity observed in plumes is attributed, but has not been firmly linked, to the precipitation and surface reactivity of Fe oxyhydroxide minerals in both buoyant and neutrally buoyant plumes 7 . The rate of hydrothermal Fe(ii) oxidation has been correlated with the redox state of local deep waters 8 ; however, roles for dissolved organic carbon 9 (DOC) and microbial activity 10 have also been hypothesized. Although hydrothermal plume processes influence important global ocean elemental cycles, there is little mechanistic information available about these processes owing to the dynamic character of the plume environment and the complexity of plume particles. Most knowledge of plume mineral composition and reactivity is inferred from either bulk digestion of filtered solids 7 or scanning electron microscopy with elemental analysis 6 . Here we use synchrotron-based X-ray absorption spectromicroscopy to investigate Fe and C speciation at the

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“…Dissolved organic carbon (DOC) concentrations in the range 10 -50 μM have been reported in hydrothermal fields. 28 The CL intensities of some heavy-metal ions and organic matter with acidic permanganate were measured. Some organic chemicals cause CL by reaction with acidic permanganate.…”

Section: Interference With CL By Heavy-metal Ions and Organic Mattermentioning

confidence: 99%

Determination of Sulfide with Acidic Permanganate Chemiluminescence for Development of Deep-sea in-situ Analyzers

et al. 2011

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A new chemiluminescence method is proposed for the determination of sulfide in seawater based on the chemiluminescence reaction between sulfide and an acidic permanganate solution. 3-Cyclohexylaminopropanesulfonic acid was used as a chemiluminescence enhancer. By use of this method, 1 -150 μM of sulfide could be determined in artificial seawater. The limit of detection was 0.17 μM sulfide. We investigated the effects of salinity, water temperature, and interfering chemicals such as heavy-metal ions and organic matter. In addition, natural seawater spiked with sulfide was analyzed. The results showed that the CL method could be applied to a deep-sea sulfide analyzer.

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Dissolved organic carbon in ridge-axis and ridge-flank hydrothermal systems

Cited by 171 publications

References 81 publications

Molecular transformation and degradation of refractory dissolved organic matter in the Atlantic and Southern Ocean

Molecular transformation and degradation of refractory dissolved organic matter in the Atlantic and Southern Ocean

Preservation of iron(II) by carbon-rich matrices in a hydrothermal plume

Determination of Sulfide with Acidic Permanganate Chemiluminescence for Development of Deep-sea in-situ Analyzers

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