Theoretical, experimental and field studies concerning molecular diffusion of radioisotopes in sediments and suspended solid particles of the sea Part A: Theories and mathematical calculations

Duursma, Egbert K.; Hoede, C.

doi:10.1016/0077-7579(67)90013-0

Cited by 59 publications

(20 citation statements)

References 2 publications

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“…However, considering theosediment layer at relatively high redox potential. Conretical aspects of diffusion in marine sediments centrations of low-molecular-weight fatty acids (as (Duursma & Hoede 1967), the distance of sulfide difpreferred carbon sources for SRB) in the pore water fusion from the main source of sulfide (peak of SRR at also showed no striking coherence with SRR maxima. 8 to 13 cm sediment depth) is expected to lie in a However, concentrations of dissolved free amino acids range between 3 and 5 cm yr-'.…”

Section: General Observationsmentioning

confidence: 99%

Dissimilatory sulfate reduction and methane production in Gotland Deep sediments (Baltic Sea) during a transition period from oxic to anoxic bottom water (1993-1996)

Piker¹,

Schmaljohann²,

Imhoff³

1998

Aquat. Microb. Ecol.

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During a transition period from oxic to anoxic conditions in the bottom water, rates of sulfate reduction and methane production, methane fluxes, as well as concentration profiles of sulfate, sulfide and methane were measured in sediments at a central site of the Gotland Deep (Stn AL 93. 241 m depth), which is regarded as representative for the deepest part of this basin. During this period from 1993 to 1996 oxic conditions in the bottom water prevailed from spring 1994 until summer 1995 with oxygen concentrations decreasing progressively with time. In the sediments methane production occurred primarily in layers below 1 m depth and flux rates of methane to the sediment surface were characterized by a steep concentrat~on gradient from approx. 5 mM at 4 m depth to values close to 30 pM at the surface, determined by diffusion processes and anaerob~c oxidation of methane. Both processes were independent of changes at the sediment surface Differences in the flux rates of methane between the deeper part with a mean value of 259 pm01 m-' d-' and the upper layers with a mean of 47.7 pm01 m-2 d-' indicate that a considerable proportion of the methane is oxidized within the anoxic horizon of the sediment (71 to 86% in the layer from 40 to 70 cm). Low rates of methane production found within the top 20 cm of the sediment during periods of oxic bottom water increased after depletion of oxygen and resulted in a clear maximum of the methane concentration in the top 2 cm. Sulfate concentrations declined exponentially from values of 11.5 mM in June 1994 and 8.5 mM in October 1995 at the sediment surface to values of 2.5 mM at 20 cm depth and of less than 0.5 mM at 50 to 60 cm depth. High sulfate reduction rates (150 to 250 nmol cm-3 d-') in the upper part of the sediment (8 to 13 cm) coincided with maxima of sulfide concentrations. During the time period of this investigation an increase of maximum sulfide concentrations in the sediment from 1 to 10 mM was measured together with decreasing oxygen concentrations in the deep water. At the same time sulfate reduction established a small but distinct maximum at the top layer of the sediment (0 to 2 cm). The relative ~mportance of sulfate reduction and methanogenesis in the carbon budget of the Gotland Deep sediments is calculated on the basis of the actual measurements.

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Section: General Observationsmentioning

confidence: 99%

Dissimilatory sulfate reduction and methane production in Gotland Deep sediments (Baltic Sea) during a transition period from oxic to anoxic bottom water (1993-1996)

Piker¹,

Schmaljohann²,

Imhoff³

1998

Aquat. Microb. Ecol.

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“…The diffusion coefficient could now be determined from microelectrode measurements of oxygen in the sediment following a momentaneous change of the overlying atmosphere from water-saturated atmospheric air to water-saturated oxygen. The change from air (20.9% oxygen) to 99% oxygen occurred within 1 s, so that the time for the application of the "constant source" (Duursma and Hoede 1967) was well defined. A constant temperature of 20°C was maintained throughout the experiment.…”

Section: Methodsmentioning

confidence: 99%

“…D@usion coeficients -The diffusion coefficient of oxygen in the sediment was measured by a modified version of the "constant source" technique described by Duursma and Hoede (1967). A 1 -cm-deep subcore with a diameter of 1.3 cm was taken from the sediment core in which the other experiments described here had been done.…”

Section: Methodsmentioning

confidence: 99%

“…The same core could be used for another determination of the diffusion coefficient after incubation for 1 day in aerated seawater. The diffusion coefficients were found by plotting the relative increase in oxygen concentration (where air saturation = 0, oxygen saturation = 1) at various depths and at various times on inverse error function paper (Duursma and Hoede 1967).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

1

Revsbech

Madsen

Jorgensen³

1986

Limnology & Oceanography

123

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Microprofiles of oxygen and oxygenic photosynthesis were measured in a photosynthetically active sediment by an oxygen microelectrode. The di&.tsion coefficient of oxygen in the uppermost 1 mm of the sediment was determined in poisoned sediment by microelectrode measurement of changes in the oxygen profile during nonsteady state conditions. The experimentally obtained data were inserted into computer models to calculate the vertical profile of the oxygen consumption rate. The calculations showed that the rate of oxygen consumption was highest at the oxic-anoxic boundary where sulfide was oxidized and in the lowest part of the photic zone. Computer models were also used to obtain more accurate profiles of oxygen production. The oxygen profiles calculated by the computer were very close to those obtained experimentally both during the steady state developed under light and during the transient conditions developed at the onset of darkness.

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“…Previous models of diffusion in sediments have assumed that the distribution coefficient K~ (ratio of the concentration on the sediment to the concentration in the solution) is constant (Duursma and Hoede, 1967). carried out a series of batch sorption experiments to define the dependence of Eu(III) sorption by deep-sea deposits on concentrations, temperature, and sediment type.…”

Section: Introductionmentioning

confidence: 99%

Isothermal Diffusion of Eu And Th in Deep-Sea Sediments: Experimental Results and a Numerical Model

Epstein

Heath²

1986

Clays and clay miner.

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Experimentally, the sorption of Eu onto clay-rich sediments was very rapid in the first few seconds and slowed over an interval of minutes to hours. Rate curves were similar in shape to those of a-iron hydroxide, rather than of the oxalate-extracted residual sediment, indicating the importance of oxyhydroxide-like phases in the uptake of Eu onto red-clay sediments. For day-rich sediments, numerical modeling reproduced the general features of a series of diffusion experiments. To a first approximation, the penetration of Eu into a sediment proceeded by saturation of the sediment to the depth of penetration and produced a sharp drop-offin sorbed + dissolved Eu concentration at the diffusion front. Higher partition coefficients (Kv) resulted in greater sorbed + dissolved concentrations, but reduced penetration. For calcareous sediments, however, Eu concentrations at the surface were much higher than at depth, presumably due to the formation of an insoluble carbonate.

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Theoretical, experimental and field studies concerning molecular diffusion of radioisotopes in sediments and suspended solid particles of the sea Part A: Theories and mathematical calculations

Cited by 59 publications

References 2 publications

Dissimilatory sulfate reduction and methane production in Gotland Deep sediments (Baltic Sea) during a transition period from oxic to anoxic bottom water (1993-1996)

Dissimilatory sulfate reduction and methane production in Gotland Deep sediments (Baltic Sea) during a transition period from oxic to anoxic bottom water (1993-1996)

1

Isothermal Diffusion of Eu And Th in Deep-Sea Sediments: Experimental Results and a Numerical Model

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