The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies

Bogus, Kara; Zonneveld, Karin A F; Fischer, David; Kasten, Sabine; Bohrmann, Gerhard; Versteegh, Gerard J.M.

doi:10.5194/bgd-8-11359-2011

Cited by 3 publications

(3 citation statements)

References 134 publications

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“…While the (quasi-)exponential decrease of the heterotrophic taxa downward from the top of the low-sedimentation cores (Figures 2 and 3) indeed would seem to be a typical signature of diagenetic bias, this alternative explanation is hard to prove with the available data and would require the analysis of additional aerobic degradation indices (cf. Bogus et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Sea surface conditions in the southern Nordic Seas during the Holocene based on dinoflagellate cyst assemblages

et al. 2016

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Dinoflagellate cyst (dinocyst) records from the southern Nordic Seas were compiled in order to evaluate the evolution of upper ocean conditions, on a millennial timescale and supported by a highly resolved record from the Vøring Plateau. After the transitional phase from the last deglaciation, three main phases define the Holocene. The early Holocene (>7.5 ka BP) features important numbers of cool-temperate species dominated by Nematosphaeropsis labyrinthus and Impagidinium pallidum in the west. The assemblage composition changes drastically at the transition from the early to the mid-Holocene, from when on Operculodinium centrocarpum dominates. The changeover is dated between ~6.1 and 7.5 ka BP, perhaps earlier closer to the Iceland–Scotland Ridge, and appears to be linked to the onset of a modern type of surface circulation. ‘Warmest’ assemblages occur at the Vøring Plateau shortly after the transition, when Atlantic waters also appear to have spread farthest westward. The recurrence of colder elements can be linked to cooling from ~2.4 ka BP at the Vøring Plateau and presumably earlier in the west but is difficult to date there because of the low sedimentation rates. This is a general issue in many areas of the Nordic Seas and appears to have an important effect on cyst concentrations and assemblage composition, with the possible loss of oxygenation-sensitive cysts in the older parts of the cores. Comparing dinocyst-based quantitative reconstructions with those retrieved from other plankton reveals a significantly different trend between proxies, linked to a differing autecological response to seasonal changes at their respective depth habitats.

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Section: Discussionmentioning

confidence: 99%

Sea surface conditions in the southern Nordic Seas during the Holocene based on dinoflagellate cyst assemblages

et al. 2016

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“…Nevertheless, several data compilations reveal that rates of OM degradation and preservation vary significantly in space Burdige, 2006;Emerson and Hedges, 1988;Middelburg, 2019) and time (Berner, 2003). Significant progress has been made over the past decades in identifying the potential environmental controls of this spatio-temporal variability (Arndt et al, 2013;Bogus et al, 2012;LaRowe et al, 2020b;Zonneveld et al, 2010). It is becoming increasingly clear that the susceptibility of OM to heterotrophic degradation is not solely an inherent characteristic of the OM itself, but also depends on its environmental context (Kayler et al, 2019;LaRowe et al, 2020b;Mayer, 1995;Schmidt et al, 2011;Zonneveld et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

New insights into large-scale trends of apparent organic matter reactivity in marine sediments and patterns of benthic carbon transformation

et al. 2021

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Abstract. Constraining the mechanisms controlling organic matter (OM) reactivity and, thus, degradation, preservation, and burial in marine sediments across spatial and temporal scales is key to understanding carbon cycling in the past, present, and future. However, we still lack a detailed quantitative understanding of what controls OM reactivity in marine sediments and, consequently, a general framework that would allow model parametrization in data-poor areas. To fill this gap, we quantify apparent OM reactivity (i.e. OM degradation rate constants) by extracting reactive continuum model (RCM) parameters (a and v, which define the shape and scale of OM reactivity profiles, respectively) from observed benthic organic carbon and sulfate dynamics across 14 contrasting depositional settings distributed over five distinct benthic provinces. We further complement the newly derived parameter set with a compilation of 37 previously published RCM a and v estimates to explore large-scale trends in OM reactivity. Our analysis shows that the large-scale variability in apparent OM reactivity is largely driven by differences in parameter a (10−3–107) with a high frequency of values in the range 100–104 years. In contrast, and in broad agreement with previous findings, inversely determined v values fall within a narrow range (0.1–0.2). Results also show that the variability in parameter a and, thus, in apparent OM reactivity is a function of the whole depositional environment, rather than traditionally proposed, single environmental controls (e.g. water depth, sedimentation rate, OM fluxes). Thus, we caution against the simplifying use of a single environmental control for predicting apparent OM reactivity beyond a specific local environmental context (i.e. well-defined geographic scale). Additionally, model results indicate that, while OM fluxes exert a dominant control on depth-integrated OM degradation rates across most depositional environments, apparent OM reactivity becomes a dominant control in depositional environments that receive exceptionally reactive OM. Furthermore, model results show that apparent OM reactivity exerts a key control on the relative significance of OM degradation pathways, the redox zonation of the sediment, and rates of anaerobic oxidation of methane. In summary, our large-scale assessment (i) further supports the notion of apparent OM reactivity as a dynamic ecosystem property, (ii) consolidates the distributions of RCM parameters, and (iii) provides quantitative constraints on how OM reactivity governs benthic biogeochemical cycling and exchange. Therefore, it provides important global constraints on the most plausible range of RCM parameters a and v and largely alleviates the difficulty of determining OM reactivity in RCM by constraining it to only one variable, i.e. the parameter a. It thus represents an important advance for model parameterization in data-poor areas.

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“…This so-called Findlater Jet causes upwelling off Oman, which is the major process in the Arabian Sea controlling biological productivity and the associated export of organic matter from the sunlit surface ocean into the deep sea during the summer monsoon (Brock et al, 1991(Brock et al, , 1992Rixen et al, 2000Rixen et al, , 2009. The monsoon-driven export of organic matter and its respiration in combination with a restricted circulation within the permanent thermocline form and maintain an oxygen minimum zone, which is most pronounced at water-depths between 100 and 1000 m in the northern part of the Arabian Sea (Bogus et al, 2012;Fischer et al, 2013;Gaye et al, 2013;Rixen et al, 2014;Rixen and Ittekkot, 2005;Sen Gupta et al, 1976;Wilhelms-Dick et al, 2012). Off Pakistan, where the oxygen-deficient water flushes the continental slope, dark-olive and bright alternating laminated sediments are formed due to a reduced bioturbation in the absence of higher organisms avoiding such oxygen-deficient waters (e.g.…”

Section: Study Areamentioning

confidence: 99%

Sources of laminated sediments in the northeastern Arabian Sea off Pakistan and implications for sediment transport mechanisms during the late Holocene

et al. 2018

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Laminated sediments of the continental slope off the Makran coast in the northern Arabian Sea are well-known climate archives and record productivity, as well as supply of material from land. Here, we studied sediment core 275KL off Pakistan in concert with sediment trap, dust and river samples in order to characterize and quantify land-derived material deposited in varves and event layers. We analysed grain sizes, mineral assemblages, bulk components and stable isotopes (δ 13 C, δ 18 O) of carbonates. In winter, enhanced river discharge is the main source of lithogenic matter contributing the major amounts to the total annual sedimentation of the northern Arabian Sea. During the late summer season, lithogenic matter accumulation is slightly enhanced, probably carried along with the south-eastward blowing Levar winds from the Balochistan and the Sistan Basins and the summer monsoon discharge maximum of perennial streams. C/N ratios and stable carbon and oxygen isotopes could not be used to distinguish between organic matter produced on land and in the ocean, whereas stable carbon and oxygen isotope ratios of carbonates suggest that sedimentation of event layers is dominated by direct inputs from land. Catastrophic denudation and storm events occur on average once every 50 years and lead to sedimentation rates that exceed the mean annual sedimentations of 983 g m −2 yr −1 by 6 to 10 times. Nevertheless, due to their rare occurrence, they contributed only 7% to the total sedimentation during the last ca. 5000 years. End-member modelling of grain sizes in accordance with lithogenic matter accumulation rates and event layer frequencies showed that arid conditions prevailed between 4000 and 5000 a BP while more humid conditions commenced around 2000 ka BP in accordance with the Pacific ENSO record.

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The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies

Cited by 3 publications

References 134 publications

Sea surface conditions in the southern Nordic Seas during the Holocene based on dinoflagellate cyst assemblages

Sea surface conditions in the southern Nordic Seas during the Holocene based on dinoflagellate cyst assemblages

New insights into large-scale trends of apparent organic matter reactivity in marine sediments and patterns of benthic carbon transformation

Sources of laminated sediments in the northeastern Arabian Sea off Pakistan and implications for sediment transport mechanisms during the late Holocene

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