Preservation of Organic Matter in Marine Sediments: Controls, Mechanisms, and an Imbalance in Sediment Organic Carbon Budgets?

ChemInform ◽  
2007 ◽  
Vol 38 (20) ◽  
Author(s):  
David J. Burdige
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Marine Sediments ◽  
Carbon Budgets ◽  
Sediment Organic Carbon

A novel approach to quantifying resuspension resistance of sediment organic matter against coastal flow

2020 ◽  
Author(s):  
Naiyu Zhang ◽  
Charlotte Thompson ◽  
Ian Townend
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Marine Sediments ◽  
Microcomputed Tomography ◽  
Sediment Organic Matter ◽  
Flow Conditions ◽  
X Ray ◽  
Continental Shelves ◽  
Sediment Organic Carbon ◽  
Organo Clay

<p>In order to estimate sediment organic carbon budget in coastal oceans and continental shelves, a first step is to estimate how much of the deposited organic matter is retained within a sediment matrix, for further remineralization and preservation on a geological timescale, rather being physically flushed away by benthic flow<sup>1</sup>. This question becomes more challenging for the regions where ‘mobile’ layers (e.g. fluff layer, fluid mud and nepheloid layer) are formed due to the massive organic matter inputs, and often frequent resuspension and deposition<sup>2</sup>. Organic matter remineralization and preservation in sediments has been mostly investigated but often overlooks the role of flow-induced shear stresses on suspending the organic matter. While such flow influences in sediment organic matter budget may have little influence on sediment organic matter budget in deep oceans, it cannot be neglected in shallow-water coastal seas and continental shelves where cyclic resuspension, deposition and frequent storm events occur<sup>3,4</sup>. To our knowledge, the resistance strengths of organic matter in sediments against flow resuspension has received little attention.</p><p>To investigate this knowledge gap, various organo-clay aggregates and organo-clay-sand aggregates formed under different flow conditions were investigated by a series of laboratory flume<sup>5</sup> and high resolution X-ray Microcomputed Tomography (micro-CT) experiments<sup>6</sup>. Herein, a novel methodology is proposed, which successfully establishes quantitative relationships between the resuspension resistance strengths of these organic aggregates and a wide range of flow intensities, from moderate to storm conditions. The results provide a basis for computing resuspension under a range of flow conditions and, hence improving estimates of the organic matter budget in the coastal zone.  </p><p> </p><p><strong>References</strong></p><ol><li>Burdige, D. J. Preservation of organic matter in marine sediments: Controls, mechanisms, and an imbalance in sediment organic carbon budgets? Chem. Rev. <strong>107</strong>, 467–485 (2007).</li> <li>McKee, B. A., Aller, R. C., Allison, M. A., Bianchi, T. S. & Kineke, G. C. Transport and transformation of dissolved and particulate materials on continental margins influenced by major rivers: Benthic boundary layer and seabed processes. Cont. Shelf Res. (2004). doi:10.1016/j.csr.2004.02.009</li> <li>Burdige, D. J. Burial of terrestrial organic matter in marine sediments: A re-assessment. Global Biogeochem. Cycles <strong>19</strong>, 1–7 (2005).</li> <li>Nicholls, R. J. & Cazenave, A. Sea-level rise and its impact on coastal zones. Science (2010). doi:10.1126/science.1185782</li> <li>Thompson, C. E. L., Couceiro, F., Fones, G. R. & Amos, C. L. Shipboard measurements of sediment stability using a small annular flume-core mini flume (cmf). Limnol. Oceanogr. Methods (2013). doi:10.4319/lom.2013.11.604</li> <li>Zhang, N. et al. Nondestructive 3D Imaging and Quantification of Hydrated Biofilm-Sediment Aggregates Using X-ray Microcomputed Tomography. Environ. Sci. Technol. <strong>52</strong>, 13306–13313 (2018).</li> </ol>

Oxygenation and organic-matter preservation in marine sediments: Direct experimental evidence from ancient organic carbon–rich deposits

Geology ◽  
2005 ◽  
Vol 33 (11) ◽  
pp. 889 ◽  
Author(s):  
Leon Moodley ◽  
Jack J. Middelburg ◽  
Peter M.J. Herman ◽  
Karline Soetaert ◽  
Gert J. de Lange
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Experimental Evidence ◽  
Marine Sediments ◽  
Direct Experimental Evidence

scholarly journals Reviews and syntheses: to the bottom of carbon processing at the seafloor

2018 ◽  
Vol 15 (2) ◽  
pp. 413-427 ◽  
Author(s):  
Jack J. Middelburg
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Secondary Production ◽  
Ecological Approach ◽  
Labile Organic Matter ◽  
Carbon Supply ◽  
Sediment Organic Carbon ◽  
Compositional Changes ◽  
Carbon Processing ◽  
Organic Resources

Abstract. Organic carbon processing at the seafloor is studied by biogeochemists to quantify burial and respiration, by organic geochemists to elucidate compositional changes and by ecologists to follow carbon transfers within food webs. Here I review these disciplinary approaches and discuss where they agree and disagree. It will be shown that the biogeochemical approach (ignoring the identity of organisms) and the ecological approach (focussing on growth and biomass of organisms) are consistent on longer timescales. Secondary production by microbes and animals is identified to potentially impact the composition of sedimentary organic matter. Animals impact sediment organic carbon processing by microbes in multiple ways: by governing organic carbon supply to sediments, by aeration via bio-irrigation and by mixing labile organic matter to deeper layers. I will present an inverted microbial loop in which microbes profit from bioturbation rather than animals profiting from microbial processing of otherwise lost dissolved organic resources. Sediments devoid of fauna therefore function differently and are less efficient in processing organic matter with the consequence that more organic matter is buried and transferred from Vernadsky's biosphere to the geosphere.

scholarly journals Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska

2021 ◽  
Vol 8 ◽  
Author(s):  
Emily M. Bristol ◽  
Craig T. Connolly ◽  
Thomas D. Lorenson ◽  
Bruce M. Richmond ◽  
Anastasia G. Ilgen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Late Pleistocene ◽  
21St Century ◽  
Marine Sediments ◽  
Coastal Erosion ◽  
Beaufort Sea ◽  
The Arctic ◽  
The Holocene ◽  
Kuparuk River

Accelerating erosion of the Alaska Beaufort Sea coast is increasing inputs of organic matter from land to the Arctic Ocean, and improved estimates of organic matter stocks in eroding coastal permafrost are needed to assess their mobilization rates under contemporary conditions. We collected three permafrost cores (4.5–7.5 m long) along a geomorphic gradient near Drew Point, Alaska, where recent erosion rates average 17.2 m year−1. Down-core patterns indicate that organic-rich soils and lacustrine sediments (12–45% total organic carbon; TOC) in the active layer and upper permafrost accumulated during the Holocene. Deeper permafrost (below 3 m elevation) mainly consists of Late Pleistocene marine sediments with lower organic matter content (∼1% TOC), lower C:N ratios, and higher δ13C values. Radiocarbon-based estimates of organic carbon accumulation rates were 11.3 ± 3.6 g TOC m−2 year−1 during the Holocene and 0.5 ± 0.1 g TOC m−2 year−1 during the Late Pleistocene (12–38 kyr BP). Within relict marine sediments, porewater salinities increased with depth. Elevated salinity near sea level (∼20–37 in thawed samples) inhibited freezing despite year-round temperatures below 0°C. We used organic matter stock estimates from the cores in combination with remote sensing time-series data to estimate carbon fluxes for a 9 km stretch of coastline near Drew Point. Erosional fluxes of TOC averaged 1,369 kg C m−1 year−1 during the 21st century (2002–2018), nearly doubling the average flux of the previous half-century (1955–2002). Our estimate of the 21st century erosional TOC flux year−1 from this 9 km coastline (12,318 metric tons C year−1) is similar to the annual TOC flux from the Kuparuk River, which drains a 8,107 km2 area east of Drew Point and ranks as the third largest river on the North Slope of Alaska. Total nitrogen fluxes via coastal erosion at Drew Point were also quantified, and were similar to those from the Kuparuk River. This study emphasizes that coastal erosion represents a significant pathway for carbon and nitrogen trapped in permafrost to enter modern biogeochemical cycles, where it may fuel food webs and greenhouse gas emissions in the marine environment.

Terrigenous Organic Matter in Surface Sediments from the Gulf of St. Lawrence

1976 ◽  
Vol 33 (1) ◽  
pp. 93-97 ◽  
Author(s):  
Roger Pocklington
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Marine Sediments ◽  
Carbon Concentration ◽  
Surface Sediments ◽  
Pulp And Paper ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Organic Carbon Concentration ◽  
Close Proximity

Marine sediments containing land-derived organic matter can be identified by a combination of high organic carbon concentration, high C and H relative to N, and the presence of lignin. Sediments with this combination of characteristics have been found in certain environments within the Gulf of St. Lawrence, in particular, in close proximity to pulp and paper mills.

scholarly journals Reviews and Synthesis: To the bottom of carbon processing at the seafloor

2017 ◽  
Author(s):  
Jack J. Middelburg
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Secondary Production ◽  
Ecological Approach ◽  
Labile Organic Matter ◽  
Carbon Supply ◽  
Sediment Organic Carbon ◽  
Compositional Changes ◽  
Carbon Processing ◽  
Organic Resources

Abstract. Organic carbon processing at the seafloor is studied by geologists to better understand the sedimentary record, by biogeochemists to quantify burial and respiration, by organic geochemists to elucidate compositional changes and by ecologists to follow carbon transfers within food webs. Here I review these disciplinary approaches and discuss where they agree and disagree. It shown that the biogeochemical approach (ignoring the identity of organisms) and the ecological approach (focussing on growth and biomass of organisms) are consistent on longer time scales. It is hypothesized that secondary production by microbes and animals might impact the composition of sedimentary organic matter eventually buried. Animals impact sediment organic carbon processing by microbes in multiple ways: by governing organic carbon supply to sediments and by mixing labile organic matter to deeper layers. An inverted microbial loop is presented in which microbes profit from bioturbation rather than animals profiting from microbial processing of otherwise lost dissolved organic resources. Sediments devoid of fauna therefore function differently and are less efficient in processing organic matter with the consequence that more organic matter is buried and transferred from Vernadsky’s biosphere to the geosphere.

An adsorption and thermodynamic study of ofloxacin on marine sediments

2017 ◽  
Vol 14 (6) ◽  
pp. 350 ◽  
Author(s):  
Wen-Qing Cao ◽  
Jun Song ◽  
Gui-Peng Yang
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Marine Sediments ◽  
Adsorption Process ◽  
Entropy Change ◽  
Natural Seawater ◽  
Organic Carbon Content ◽  
Adsorption Behaviour ◽  
H2o2 Treatment ◽  
Sediment Organic Carbon

Environmental contextOfloxacin, a widely used fluorinated antibiotic, is resistant to biodegradation and hence can accumulate in the environment. A systematic investigation of ofloxacin on marine sediments showed that sediment organic carbon and heterogeneous sites on sediments play important roles in adsorption processes. The results help our understanding of the environmental behaviour and fate of ofloxacin in marine systems. AbstractThe adsorption behaviour of ofloxacin (OFL) on marine sediments treated by different methods was investigated using batch experiments. Three factors (sediment organic carbon content, salinity and temperature) that may affect the adsorption behaviour of OFL were analysed. The equilibrium time for OFL adsorption on marine sediment in natural seawater was ~4–5h. The adsorption of OFL on all sediments with different treatments fitted the Freundlich model well. The adsorption parameter Kf value was in the order of Kf (H2O2 treatment)<Kf (H2O treatment)<Kf (HCl treatment) over the studied concentration range. The adsorption of OFL was influenced not only by the sediment organic carbon content but also by external factors such as salinity of media and temperature. The adsorption was favourably influenced by decreased salinity and temperature of seawater. The adsorption capacity of OFL on marine sediments decreased with an increase of temperature and salinity. The Kf values decreased from 33.73±1.66 to 22.54±1.12(Lkg−1)1/n when the temperature increased from 283 to 313K. The changes in standard Gibbs free energy (ΔG0) and enthalpy (ΔH0) were −6.62±0.34kJmol−1 and −7.58±0.38kJmol−1 respectively, indicating that the adsorption process of OFL was spontaneous and exothermic. The positive value of the entropy change ΔS0 (i.e. 3.38±0.17JK−1mol−1) suggests that the degree of freedom increased during the adsorption process.

Earth’s Middle Ages: What Came after the GOE

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Middle Ages ◽  
Atmospheric Oxygen ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Dissolved Iron ◽  
Great Oxidation Event ◽  
Low Levels ◽  
Substantial Rise

This chapter considers the aftermath of the great oxidation event (GOE). It suggests that there was a substantial rise in oxygen defining the GOE, which may, in turn have led to the Lomagundi isotope excursion, which was associated with high rates of organic matter burial and perhaps even higher concentrations of oxygen. This excursion was soon followed by a crash in oxygen to very low levels and a return to banded iron formation deposition. When the massive amounts of organic carbon buried during the excursion were brought into the weathering environment, they would have represented a huge oxygen sink, drawing down levels of atmospheric oxygen. There appeared to be a veritable seesaw in oxygen concentrations, apparently triggered initially by the GOE. The GOE did not produce enough oxygen to oxygenate the oceans. Dissolved iron was removed from the oceans not by reaction with oxygen but rather by reaction with sulfide. Thus, the deep oceans remained anoxic and became rich in sulfide, instead of becoming well oxygenated.

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