Production of fluorescent dissolved organic matter in Arctic Ocean sediments

Chen, Meilian; Kim, Jihoon; Nam, Sang Heon; Niessen, Frank; Hong, Wei‐Li; Kang, Min-Hee; Hur, Jin

doi:10.1038/srep39213

Cited by 86 publications

(59 citation statements)

References 69 publications

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“…These optical properties were shown to provide important information on DOM cycling and transformations in the water column (e.g Coble, 1996;Zsolnay et al, 1999;Jørgensen et al, 2011;Catalá et al, 2016;Loginova et al, 2016) and sediments (e.g. Chen et al, 2016). CDOM refers to DOM that absorbs light over a broad spectra from UV to visible wavelengths.…”

Section: Introductionmentioning

confidence: 99%

“…The distribution of CDOM within pore-waters provides important insights on processes related to organic matter remineralization. For instance, anoxic sediments in the Chukchi Sea were previously found to be a production site of humic-like substances and a potential source of pre-altered DOM into the water column (Chen et al, 2016). On the other hand, FDOM measurements made during incubation of sediment cores from Uiam Lake (Yang et al, 2014), suggested that DOM released into the overlying water may be further altered by microbial communities, and, therefore, serves as an important source of bioavailable organic matter.…”

Section: Introductionmentioning

confidence: 99%

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Sediment release of dissolved organic matter to the oxygen minimum zone off Peru

Loginova¹,

Dale²,

Thomsen³

et al. 2020

Preprint

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Abstract. The eastern tropical South Pacific (ETSP) represents one of the most productive areas in the ocean that is characterized by a pronounced oxygen minimum zone (OMZ). Particulate organic matter (POM) that sinks out of the euphotic zone is supplied to the anoxic sediments and utilized by microbial communities. The degradation of POM is associated with dissolved organic matter (DOM) production and reworking. The release of recalcitrant DOM to the overlying waters may represent an important organic matter escape mechanism from remineralization within sediments but received little attention in OMZ regions so far. Here, we combine measurements of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) with DOM optical properties in the form of chromophoric (CDOM) and fluorescent (FDOM) DOM from pore waters and near-bottom waters of the ETSP off Peru. We evaluate diffusion&#8211;driven fluxes and net in situ fluxes of DOC and DON in order to investigate processes affecting DOM cycling at the sediment&#8211;water interface along a transect 12&#176;&#8201;S. To our knowledge, these are the first data for sediment release of DON and pore water CDOM and FDOM for the ETSP off Peru. Pore-water DOC and DON accumulated with increasing sediment depth, suggesting an imbalance between DOM production and remineralization within sediments. High DON accumulation resulted in very low pore water DOC&#8201;/&#8201;DON ratios (>&#8201;1) which could be caused by either an <q>imbalance</q> in DOC and DON remineralization, or to the presence of an additional nitrogen source. Diffusion driven fluxes of DOC and DON exhibited high spatial variability. They varied from 0.2&#8211;0.1&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1 to 2.52&#8211;1.3&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1 and from &#8722;0.042&#8211;0.02&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1 to 3.32&#8211;1.7&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1, respectively. Generally low net in situ DOC and DON fluxes as well as steepening of spectral slope (S) of CDOM and accumulation of humic-like FDOM at the near-bottom waters over time indicated active microbial DOM utilization at the sediment&#8211;water interface, potentially stimulated by nitrate (NO3&#8722;) and nitrite (NO2&#8722;). The microbial DOC utilization rates, estimated in our study, may be sufficient to support denitrification rates of 0.2&#8211;1.4&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1, suggesting that sediment release of DOM contributes substantially to nitrogen loss processes in the ETSP off Peru.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sediment release of dissolved organic matter to the oxygen minimum zone off Peru

Loginova¹,

Dale²,

Thomsen³

et al. 2020

Preprint

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“…Production of FDOM above the SMTZ was also observed in the Arctic sediments, in which a shallow site at the Chukchi Shelf receiving large organic matter loadings featured the most pronounced production 34 . Furthermore, the exponential production of DOC, CDOM, and FDOM above the SMTZ were concomitant with the time-dependent variations of nutrients and alkalinity (i.e., exponential increasing trends) and sulfate (i.e., exponential decreasing trend) in pore waters (Fig.…”

Section: Discussionmentioning

confidence: 79%

Biological early diagenesis and insolation-paced paleoproductivity signified in deep core sediment organic matter

Chen

Kim

Choi

et al. 2017

Sci Rep

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The dynamics of a large stock of organic matter contained in deep sediments of marginal seas plays pivotal role in global carbon cycle, yet it is poorly constrained. Here, dissolved organic matter (DOM) in sediments was investigated for core sediment up to ~240 meters deep in the East/Japan Sea. The upper downcore profile (≤118 mbsf, or meters below seafloor) at a non-chimney site (U1) featured the exponential production of dissolved organic carbon (DOC) and optically active DOM with time in the pore water above sulfate-methane-transition-zone (SMTZ), concurrent with the increases of nutrients and alkalinity, and the reduction of sulfate. Such depth profiles signify a biological pathway of the DOM production during the early diagenesis of particulate organic matter presumably dominated by sulfate reduction. Below the SMTZ, an insolation-paced oscillation of DOM in a ~405-Kyr cycle of orbital eccentricity was observed at site U1, implying astronomically paced paleoproductivity stimulated by light availability. Furthermore, DOM dynamics of the deep sediments were likely governed by intensive humification as revealed by the less pronounced protein-like fluorescence and the lower H/C and O/C ratios below SMTZ among 15,281 formulas identified. Our findings here provide novel insights into organic matter dynamics in deep sediments.

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“…Murphy [23] used laboratory experiments to demonstrate that in the presence of humic acids Th(IV) sorption to hematite was greatly enhanced [24]. Therefore, humic-like substances may play a role in Th cycling in the Arctic Ocean, e.g., [25,26].…”

Section: Discussionmentioning

confidence: 99%

Mineral Phase-Element Associations Based on Sequential Leaching of Ferromanganese Crusts, Amerasia Basin Arctic Ocean

et al. 2018

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Ferromanganese (FeMn) crusts from Mendeleev Ridge, Chukchi Borderland, and Alpha Ridge, in the Amerasia Basin, Arctic Ocean, are similar based on morphology and chemical composition. The crusts are characterized by a two- to four-layered stratigraphy. The chemical composition of the Arctic crusts differs significantly from hydrogenetic crusts from elsewhere of global ocean by high mean Fe/Mn ratios, high As, Li, V, Sc, and Th concentrations, and high detrital contents. Here, we present element distributions through crust stratigraphic sections and element phase association using several complementary techniques such as SEM-EDS, LA-ICP-MS, and sequential leaching, a widely employed method of element phase association that dissolves mineral phases of different stability step-by-step: Exchangeable cations and Ca carbonates, Mn-oxides, Fe-hydroxides, and residual fraction. Sequential leaching shows that the Arctic crusts have higher contents of most elements characteristic of the aluminosilicate phase than do Pacific crusts. Elements have similar distributions between the hydrogenetic Mn and Fe phases in all the Arctic and Pacific crusts. The main host phases for the elements enriched in the Arctic crusts over Pacific crusts (Li, As, Th, and V) are the Mn-phase for Li and Fe-phase for As, Th, and V; those elements also have higher contents in the residual aluminosilicate phase. Thus, higher concentrations of Li, As, Th, and V likely occur in the dissolved and particulate phases in bottom waters where the Arctic crusts grow, which has been shown to be true for Sc, also highly enriched in the crusts. The phase distributions of elements within the crust layers is mostly consistent among the Arctic crusts, being somewhat different in element concentrations in the residual phase.

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Production of fluorescent dissolved organic matter in Arctic Ocean sediments

Cited by 86 publications

References 69 publications

Sediment release of dissolved organic matter to the oxygen minimum zone off Peru

Sediment release of dissolved organic matter to the oxygen minimum zone off Peru

Biological early diagenesis and insolation-paced paleoproductivity signified in deep core sediment organic matter

Mineral Phase-Element Associations Based on Sequential Leaching of Ferromanganese Crusts, Amerasia Basin Arctic Ocean

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