Mineralogical and textural controls on the organic composition of coastal marine sediments: Hydrodynamic separation using SPLITT-fractionation

Keil, Richard G.; Tsamakis, Elizabeth; Fuh, C. Bor; Giddings, J. Calvin; Hedges, John I.

doi:10.1016/0016-7037(94)90512-6

Cited by 467 publications

(262 citation statements)

References 30 publications

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“…Excess OM was also observed in some ETS sediments found on banks within the euphotic zone (,60 m) and regionally high b-diversity of infauna was observed at these depths . Higher than monolayer-equivalent loadings can also occur in course sediment fractions (,3 m 2 g À1 ) due to the occurrence of discrete OM debris (Keil et al 1994). This was likely the case in outer shelf channel and scree sediments in the ETS (Fig.…”

Section: Organic Carbonmentioning

confidence: 94%

Baseline biogeochemical data from Australia's continental margin links seabed sediments to water column characteristics

Radke

Nicholas

Thompson

et al. 2017

Mar. Freshwater Res.

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Abstract. Surficial marine sediments are an important source of nutrients for productivity and biodiversity, yet the biogeochemistry of these sediments is poorly known in Australia. Seabed samples were collected at .350 locations in Australia's western, northern and eastern continental margins during Federal Government surveys . Parameters analysed included measures of organic matter (OM) source (d 13 C, d 15 N and C : N ratios), concentration (percentage total organic carbon, %TOC, and surface area-normalised TOC, OC : SA) and bioavailability (chlorin indices, total reactive chlorins, total oxygen uptake, total sediment metabolism (TSM), sediment oxygen demand (SOD) and SOD and TSM normalised against TOC). The aim of the present study was to summarise these biogeochemical 'baseline' data and make contextualised inferences about processes that govern the observed concentrations. The OM was primarily from marine sources and the OC : SA broadly reflected water column productivity (based on Moderate Resolution Imaging Spectroradiometer, MODIS). Approximately 40% of sediments were organic poor by global standards, reflecting seawater oligotrophy; ,12% were organic rich due to benthic production, high water column productivity and pockmark formation. OM freshness varied due to pigment degradation in water columns and dilution with refractory OM in reworked sediments. d 15 N values confirmed the importance of N 2 fixation to Timor Sea productivity, and point to recycling of fixed nitrogen within food chains in Western Australia.

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Section: Organic Carbonmentioning

confidence: 94%

Baseline biogeochemical data from Australia's continental margin links seabed sediments to water column characteristics

Radke

Nicholas

Thompson

et al. 2017

Mar. Freshwater Res.

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“…Samples were taken from 130-to 200-cm core depths at 1-cm interval between HLs and at 0.5 cm within HLs 4 and 5, which were identified at core depths of 144.0 to 153.5 cm and 187.0 to 193.5 cm, respectively (Huon et al, 2002). Thirteen samples between 10 and 30 cm, representing Holocene (postglacial) sediments, were also analyzed to better constrain the possible overprint of diagenesis on P. The use of the Ͻ50-m-sized fraction of sediments for this study is justified by four main reasons: (a) Organic matter from the Ͻ50-m fraction from the same samples was analyzed for nitrogen and carbon stable isotopes (Huon et al, 2002), so it is possible to compare results from both studies; (b) terrigenous organic matter (and related organic-bound P), transported "far off" its continental source, is rather concentrated in the fine-sized fraction, either dispersed in the sediment or bound to clay minerals (Keil et al, 1994;Christensen, 1996); (c) in continental source areas, organic matter is stabilized in the fine-sized fraction of soils (Balesdent and Mariotti, 1996), and therefore, a better characterization of continental inputs is expected from fine-sized fractions; and (d) the ratio of organic carbon vs. lithic content of bulk sediment is very low, particularly for HLs, which are enriched in coarse IRD, leading to high mineral matrix effects and reducing as much the resolution of elemental analysis. (Ruddiman, 1977).…”

Section: Methodsmentioning

confidence: 99%

“…Low values for continental organic matter can possibly reflect (a) a grain size effect (Ruttenberg and Goñi, 1997), also shown by the TOC/TN ratio (Keil et al, 1994;Huon et al, 2002); (b) the degree of organic matter mineralization in the source area; or (c) the selective preservation of organic matter in sediments.…”

Section: Selective Preservation or Change In The Source Of Organic Mamentioning

confidence: 99%

Dysaerobic conditions during Heinrich events 4 and 5: Evidence from phosphorus distribution in a North Atlantic deep-sea core

Tamburini

Huon

Steinmann

et al. 2002

Geochimica et Cosmochimica Acta

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Abstract-Reactive phosphorus undergoes diagenetic transformation once transferred into marine sediments. The degree of regeneration and redistribution of phosphorus depends on early diagenetic and environmental conditions, which may be linked to larger scale phenomena, such as bottom water circulation, water column ventilation, and organic carbon flux. Phosphorus phases of the Ͻ50-m-sized fraction of deep-sea sediments from core SU 90-09 (North Atlantic, 43°31'N, 30°24'W, 3375 m below sea level) have been analyzed using a sequential extraction technique (SEDEX method) to reconstruct phosphorus geochemistry during Heinrich events 4 and 5. Comparison with Holocene samples from the same site indicates that postdeposition diagenetic transformation has not affected phosphorus distribution in the deep part of the sediments. Total and reactive phosphorus average 0.40 Ϯ 0.04 mg/g and 0.30 Ϯ 0.05 mg/g, respectively, and are comparable to values found in analog deep-sea environments in the North Atlantic. Detrital phosphorus, the phase linked to igneous-and metamorphic-derived material, sharply increases during Heinrich events and covaries with the ice-rafted debris record, whereas authigenic and Fe-bound phosphorus phases, both influenced by redox conditions, decrease or even disappear. These findings suggest that during the deposition of Heinrich layers (HLs), environmental parameters hampered the precipitation of these phases. Large freshwater discharges in relation to iceberg surges may have provoked a temporary stratification of the water column. Accordingly, dysaerobic conditions in the sediments may have fostered the loss of dissolved phosphorus from the sediments to the water column, in a direct and rapid response to the changed conditions. Decreasing trends in organic matter elemental ratios (total organic carbon/organic phosphorus) and Rock-Eval oxygen index values, along with the presence of partly authigenic dolomite and ankerite within HLs, also support this assumption.

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“…In coastal settings, a hypothetical "monolayer equivalent" quantity of ~1 mg OC m -2 is often observed, indicating that further loss of OC is inhibited by physical or biochemical limits (Suess, 1973;Keil et al, 1994; μm flood sediments (1.7 ± 1.6 mg m -2 , n = 7) to the 150-250 μm flood sediments (3.1 ± 2.9 mg m -2 , n = 6) to the 250-1000 μm flood sediments (3.6 ± 2.6 mg m -2 , n = 6). The coarser-grained sediments therefore carry a greater loading of OC, which appears to be largely oxidized before they are physically broken down to particles which can be mobilized as suspended material.…”

Section: Sedimentological Controls On Organic Carbon Transportmentioning

confidence: 99%

Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective

Voß¹

2014

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The great geologic and climatic diversity of the Fraser River basin in southwestern Canada render it an excellent location for understanding biogeochemical cycling of sediments and terrigenous organic carbon in a relatively pristine, large, temperate watershed. Sediments delivered by all tributaries have the potential to reach the ocean due to a lack of main stem lakes or impoundments, a unique feature for a river of its size. This study documents the concentrations of a suite of dissolved and particulate organic and inorganic constituents, which elucidate spatial and temporal variations in chemical weathering (including carbonate weathering in certain areas) as well as organic carbon mobilization, export, and biogeochemical transformation. Radiogenic strontium isotopes are employed as a tracer of sediment provenance based on the wide variation in bedrock age and lithology in the Fraser basin. The influence of sediments derived from the headwaters is detectable at the river mouth, however more downstream sediment sources predominate, particularly during high discharge conditions. Bulk radiocarbon analyses are used to quantify terrestrial storage timescales of organic carbon and distinguish between petrogenic and biospheric organic carbon, which is critical to assessing the role of rivers in long-term atmospheric CO 2 consumption. The estimated terrestrial residence time of biospheric organic carbon in the Fraser basin is 650 years, which is relatively short compared to other larger rivers (Amazon, Ganges-Brahmaputra) in which this assessment has been performed, and is likely related to the limited floodplain storage capacity and non-steadystate post-glacial erosion state of the Fraser River. A large portion of the dissolved inorganic carbon load of the Fraser River (>80%) is estimated to derive from remineralization of dissolved organic carbon, particularly during the annual spring freshet when organic carbon concentrations increase rapidly. This thesis establishes a baseline for carbon cycling in a largely unperturbed modern mid-latitude river system and establishes a framework for future process studies on the mechanisms of organic carbon turnover and organic matter-mineral associations in river systems.

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Mineralogical and textural controls on the organic composition of coastal marine sediments: Hydrodynamic separation using SPLITT-fractionation

Cited by 467 publications

References 30 publications

Baseline biogeochemical data from Australia's continental margin links seabed sediments to water column characteristics

Baseline biogeochemical data from Australia's continental margin links seabed sediments to water column characteristics

Dysaerobic conditions during Heinrich events 4 and 5: Evidence from phosphorus distribution in a North Atlantic deep-sea core

Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective

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