Sediment focusing and210Pb dating: a new approach

Rowan, David J.; Cornett, R. J.; King, Karen June; Risto, B. A.

doi:10.1007/bf00678101

Cited by 34 publications

(19 citation statements)

References 19 publications

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“…Sediment focusing is the process by which sediments from shallower areas, through effects of slope, wind/wave action, and water currents, are redistributed to deeper areas of lake bottoms. Based on properties such as water depth, organic matter content, and water content of the sediments, lake bottoms can be subdivided into erosion, transportation, and accumulation zones (Håkanson and Jansson 1983;Blais and Kalff 1995;Rowan et al 1995). In the model, fine-grained material with long suspension times (i.e., low sedimentation velocities), such as organic matter, will accumulate in the deep basins of lakes, along with associated strongly bound metal ions, such as Pb (Håk-anson and Jansson 1983); therefore, the model of sediment focusing is applied by extension to interpret the accumulation of heavy metals in lake basins.…”

Section: Spheroidal Carbonaceous Flyash Particles (Scp)-temporal Trenmentioning

confidence: 99%

A whole‐basin study of sediment accumulation using stable lead isotopes and flyash particles in an acidified lake, Sweden

Bindler

Renberg

Brännvall

et al. 2001

Limnology & Oceanography

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Using analyses of lead concentrations, lead isotopes ( 206 Pb/ 207 Pb), and spheroidal carbonaceous flyash particles (SCP), we studied sediment accumulation patterns in the acidified lake Härsvatten in southwest Sweden. After determining the natural background 206 Pb/ 207 Pb ratio (1.5) in deeper sediments in long sediment cores from three basins in the lake, we applied an isotope mixing model to quantify pollution Pb accumulation in 46 gravity cores. The mean pollution Pb inventory in the cores was 2.6 g m Ϫ2 (range, 0.3-11 g m Ϫ2 ). Although some variation in Pb concentrations can be explained by loss on ignition (LOI) and water depth (together, R ϭ 0.33), there is no 2 adj relationship between pollution Pb inventories and these variables. Contrary to the traditional model of sediment focusing, where higher accumulations of pollutants are expected in deeper waters, the highest inventories for pollution Pb and SCP are generally found at shallow sites (Ͻ4 m water depth) and not in the three deep basins of the lake (10, 12, and 24 m deep). Furthermore, the model for sediment focusing, which may be appropriate for describing the physical building of sediments in a lake basin, may be inappropriate for describing the specific processes controlling the distribution of pollutants in a lake basin of this type.

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Section: Spheroidal Carbonaceous Flyash Particles (Scp)-temporal Trenmentioning

confidence: 99%

A whole‐basin study of sediment accumulation using stable lead isotopes and flyash particles in an acidified lake, Sweden

Bindler

Renberg

Brännvall

et al. 2001

Limnology & Oceanography

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“…Since these organisms occupy different areas of the lake, a key question becomes 'how uniformly are radionuclides distributed in lake sediments m these different areas?' Once added to the lake, radionuclides do not tend to partition uniformly across the sediment surface [12]. Instead, radionuclides can migrate both horizontally and vertically in the sediments as a different areas?'…”

Section: Resultsmentioning

confidence: 99%

“…Instead, radionuclides can migrate both horizontally and vertically in the sediments as a different areas?' Once added to the lake, radionuclides do not tend to partition uniformly across the sediment surface [12]. Instead, radionuclides can migrate both horizontally and vertically in the sediments as a function of factors, such as sediment type, composition, hydraulic conductivity and radionuclide binding affinities.…”

Section: Resultsmentioning

confidence: 99%

The importance of the sediment pathway in the radionuclide dose received by aquatic non-human biota: Reconstruction and mapping of spatiotemporal partitioning in Perch lake sediments over a 40-year period

Yankovich

2002

Radioprotection

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Abstract. There is a growing interest in assessing risk to non-human biota following exposure to radionuclides.However, before dose to aquatic biota can be determined, it is critical to have a solid understanding of radionuclide concentrations in key environmental phases due to their importance in determining external and internal dose. Further understanding of a system can be reached by monitoring temporal changes in radionuclide levels in these phases, especially if assessing the success of remediation activities. The current study has focused on estimating inputs of 90 Sr, 137 Cs and 60 Co to the sediments of a small, Canadian Shield lake located downstream of two Waste Management Areas at AECL's, Chalk River Laboratories site over a 40-year period. Overall, it was found that 137 Cs and 60 Co inputs have declined in the lake over the last 40 years, which resulted in a net depletion of these radionuclides from the sediments over time. Strontium-90 inputs have remained fairly constant over this time period with 90 Sr retention in lake sediments of approximately 15%. It is expected that benthic biota will receive approximately a 2-to 6-fold higher radionuclide dose than pelagic organisms, on average, particularly when feeding in the depositional zone of the lake.

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“…These have mostly involved modeling of wave-driven redistribution of sediment from shallow to deeper water (e.g., Sheng and Lick 1979;Bengtsson and Hellstr€ om 1992;L€ ovstedt and Bengtsson 2008). Rowan et al (1992) quantified the mud deposition boundary depth and used this to determine the locate and optimize the number of cores needed to estimate mean sedimentation rates (Rowan et al 1995). More recently, Mackay et al (2012) examined the effects of windwaves, currents and bed slopes and wind-induced currents, on sediment redistribution and argued that the heterogeneity of carbon and phosphorus deposition patterns in small lakes is largely due to such factors.…”

Section: Evaluation Of Alternative Sediment Focusing Mechanismsmentioning

confidence: 99%

“…Rowan et al (1995), for example, present a sampling framework for 210 Pb dating based on the mud deposition boundary depth (Rowan et al 1992). This interprets lake bathymetry to identify erosional, depositional, and transitional zones according to the effectiveness of wave resuspension.…”

mentioning

confidence: 99%

Three‐dimensional hydrodynamic and sediment transport modeling to test the sediment focusing hypothesis in upland lakes

Morales-Marín

French

Burningham

et al. 2017

Limnology & Oceanography

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Palaeolimnological studies rely on assumptions regarding the distribution and completeness of lake deposits that are not always fully supported by observations. In particular, the assumption that "focusing" of suspended sediments leads to preferential deposition in the deepest part of a lake is not always justified, especially in upland lakes subject to energetic wind forcing. Few studies have investigated the hydrodynamic controls on lake sediment focusing, especially the importance of wind-driven currents in deep water. We combine a three-dimensional numerical hydrodynamic and suspended sediment model (FVCOM) with a semi-empirical wind wave model to investigate the potential mobility of bottom sediments in a small oligotrophic upland lake (Llyn Conwy, north Wales, UK). Exploratory simulations of wave-and current-generated bottom stress and suspended sediment dynamics confirm the expected importance of wave-generated bottom stresses in shallower waters (< 3 m depth) around the shore. Field survey shows that lake sediments are largely absent from this zone. This is consistent with peripheral wave action as a sediment focusing mechanism. In deeper water, wind-driven currents become the dominant contributor to bottom stress. Strong wind forcing events drive an energetic circulation with peak bottom stresses that intermittently exceed any realistic erosion threshold over a large proportion of the lake at depths far below those at which waves can be effective. The spatial distribution of lake sediments, and the completeness of the sediment record, is thus determined by a complex interaction between wind-driven circulation and bathymetry, rather than by bathymetry alone. Although our sediment dynamics simulations are purely exploratory, the results are consisted with survey results that show a patchy distribution of deep-water accumulation. Some implications of these results for the selection of sediment coring locations and the interpretation of sediment records are considered.

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Sediment focusing and210Pb dating: a new approach

Cited by 34 publications

References 19 publications

A whole‐basin study of sediment accumulation using stable lead isotopes and flyash particles in an acidified lake, Sweden

A whole‐basin study of sediment accumulation using stable lead isotopes and flyash particles in an acidified lake, Sweden

The importance of the sediment pathway in the radionuclide dose received by aquatic non-human biota: Reconstruction and mapping of spatiotemporal partitioning in Perch lake sediments over a 40-year period

Three‐dimensional hydrodynamic and sediment transport modeling to test the sediment focusing hypothesis in upland lakes

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