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

Influence of organic matter quality on organic matter degradability in river sediments

2020 ◽  
Author(s):  
Florian Zander ◽  
Julia Gebert ◽  
Rob N. J. Comans ◽  
Alexander Groengroeft ◽  
Timo J. Heimovaara ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Pore Water ◽  
Chlorophyll Concentration ◽  
Sediment Organic Matter ◽  
Rheological Parameters ◽  
Ammonium Concentration ◽  
Organic Matter Quality ◽  
Degradation Rates ◽  
Physical Density

<p>The project BIOMUD, part of the scientific network MUDNET (www.tudelft.nl/mudnet), investigates the decomposition of sediment organic matter (SOM) in the Port of Hamburg. The microbial turnover of sediment organic matter under reducing conditions leads to the formation of methane, carbon dioxide and others gases causing a change in the sediment rheological parameters. BIOMUD is aiming to explain the effect of organic matter lability on the rheological properties impacting the navigable depth of the harbour.</p><p>Samples of freshly deposited material were taken in 2018 and 2019 at nine locations in a transect of 30 km through the Port of Hamburg. Analyses included abiotic parameters (among others grain size distribution, standard pore water properties, standard solid properties, stable isotopes, mineral composition) and biotic parameters (among others anaerobic and aerobic organic matter degradation, DNA, protein and lipid content, microbial population). At four locations, physical density fractions and chemical organic matter fractions were analysed.</p><p>The quality of organic matter was described by normalising carbon released from microbial degradation under both aerobic and anaerobic conditions to the share of total organic carbon (mg C/g TOC). Organic matter pools with different degradation rates were used to quantify the lability of organic matter. The share of faster degradable (more labile) pools correlated strongly with the size of the hydrophilic DOC fraction, confirming results of Straathof et al. (2014) who investigated dissolved organic carbon pools in compost. The hydrophilic DOC fraction was closely correlated to the polysaccharide concentration, explaining the input of easily degradable organic matter. Moreover, the amount of organic carbon present in the sediment’s light density fraction < 1.4 g/cm<sup>3</sup> strongly correlated with the hydrophilic DOC fraction and, less strongly, with organic matter lability. High organic matter quality, i.e. the labile, easily degradable fraction, was further related to the chlorophyll concentration in the water column but also the ammonium concentration in the sediment’s pore water.</p><p>It was hypothesised that the observed toposequence of decreasing organic matter quality from upstream to downstream could be explained by a chronosequence of increasing degradation and therefore ageing of organic matter as the sediment passes through the harbour area. Further, it was hypothesized that the harbour received organic matter of higher degradability, originating from phytoplankton biomass, from the upstream part of the Elbe river, whereas the input from the tidal downstream area provided organic matter of lower quality (degradability).</p><p>This study was funded by Hamburg Port Authority.</p>

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 Fluorescence Properties of the Air- and Freeze-Drying Treatment on Size-Fractioned Sediment Organic Matter

2021 ◽  
Vol 11 (17) ◽  
pp. 8220
Author(s):  
Cheng-Wen Chuang ◽  
Wei-Shiang Huang ◽  
Yung-Yu Liu ◽  
Chi-Ying Hsieh ◽  
Ting-Chien Chen
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Organic Carbon ◽  
Freeze Drying ◽  
Biological Activities ◽  
Sediment Organic Matter ◽  
Bulk Solution ◽  
Similar Distribution ◽  
Organic Mixture ◽  
Freeze Dried

Sediment humic substance (SHS) is a highly heterogeneous and complex organic mixture with a broad molecular weight range. It is the significant component that associates distribution, transport, and biotoxicity of pollutants in a river environment. Air- and freeze-drying sediment pre-treatment may cause different biological activity and may result in different chemical quantities and sediment organic matter. This study collected sediments that received livestock wastewater discharge. The sediments were air- (AD) and freeze-dried (FD). The dried sediment organic matter was extracted with an alkaline solution and separated into three size-fractioned SHS samples. Size-fractioning is an effective method used to differentiate materials, on a molecular level. The bulk solution (<0.45 μm) was designated as BHS, and size-fractioned solutions were identified as LHS (<1 kDa), MHS (1–10 kDa), and HHS (10 kDa-0.45 μm). The AD SHS had a lower dissolved organic carbon (DOC) concentration than the FD SHS for the bulk and individual size-fractioned SHS, but the AD and FD SHS had a similar distribution of organic carbon in the size-fractioned SHS. The AD SHS had higher aromaticity (SUVA254) and an extent of humification (HIX) than the FD SHS. In addition, the high molecular weight SHS (HHS) had a higher SUVA254 but lower HIX than the MHS and LHS. The HHS had significantly lower fulvic acid but had higher humic acid-like substances than the MHS and LHS. This is possibly the reason the LHS had a higher humification degree but lower aromaticity than HHS. The size-fractioned SHS and optical indicators distinguished the difference between the chemical properties when air- or freeze-dried, due to the different degree of biological activities.

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.

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