dating of marine sediments by an incomplete mixing model

Jo Burns, 34 years old


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Use the link below to share a full-text version of this article with your friends and colleagues. Learn more. Vertical mixing of lake sediments by tubificid oligochaetes was studied in laboratory experiments by using a radioactive cesium labeled sediment marker horizon. Results from these experiments were used to develop and test a mathematical model describing tubificid sediment mixing as a dominantly advective process. Tubificids were found to mix sediments to a depth of 6—9 cm. The rate of tubificid sediment processing observed in the experiments agrees well with those reported by other workers.

This service is more advanced with JavaScript available, learn more at http: Water, Air, and Soil Pollution. Within a more general study on marine sediments in dating of marine sediments by an incomplete mixing model Gulf of Palermo Sicily, Italythe Pb ex dating method using a model with constant sedimentation rate has been applied to one sediment core. The main goal of the research was to study the Pb pollution chronology. Dating of the core has allowed evaluating the time evolution of the gulf lead concentrations. Specific activities of Cs have also been measured in the sediment core sections as an independent confirmation of the chronology derived by the Pb ex method.

Thanks for helping us catch any problems with articles on DeepDyve. We'll do our best to fix them. Check all that apply - Please note that only the first page is available if you have not selected a reading option after clicking "Read Article". Include any more information that will help us locate the issue and fix it faster for you. In the cases with constant Pb activity in the topmost sediments, the presence of a distinct Cs peak within the Pb plateau has been used as a definitive demonstration of acceleration increase in the sedimentation rate in recent years versus fast mixing. Nevertheless, some limitations can be identified in the use of semiquantitative arguments, and a global understanding of the whole Cs activity profile is then required.
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This service is more advanced with JavaScript available, learn more at http: Journal of Paleolimnology. Classical treatment of mass conservation of solids in growing sediments states an advection-diffusion equation for the bulk sediment density. Thus, the diffusion coefficient has to account for elemental processes of exchange of solid particles by pore water or reciprocally. Nevertheless, in a gravity field, these exchanges are forced and cannot be treated as diffusion but as mass flow. A compaction potential energy is defined so that its spatial gradients force a mass flow involving a conductivity function. This leads to a more consistent definition of mass sedimentation rates and to a writing of the continuity equation for density involving only an advection term. Typical bulk density profiles show an asymptotic increase with depth. With the present formulation, this can be obtained as a steady-state solution under constant sedimentation rate and constant conductivity, while the classical formulation fails to do it. Alternatively, it can be found that under these conditions, the compaction potential is a linear function of the bulk density.

Thanks for helping us catch any problems with articles on DeepDyve. We'll do our best to fix them. Check all that apply - Please note that only the first page is available if you have not selected a reading option after clicking "Read Article". Include any more information that will help us locate the issue and fix it faster for you. Within a more general study on marine sediments in the Gulf of Palermo Sicily, Italy , the Pbex dating method using a model with constant sedimentation rate has been applied to one sediment core. The main goal of the research was to study the Pb pollution chronology. Dating of the core has allowed evaluating the time evolution of the gulf lead concentrations. Specific activities of Cs have also been measured in the sediment core sections as an independent confirmation of the chronology derived by the Pbex method. The time scale has then been used to correlate lead concentrations in core sections to estimated lead emissions in air due to gasoline combustion. A good correlation between the two data series has been obtained.

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