210Pb dating by low background gamma counting

Appleby, P. G.; Nolan, P. J.; Gifford, D. W.; Godfrey, M. J.; Oldfield, Frank; Anderson, N. J.; Battarbee, R. W.

doi:10.1007/bf00026640

Cited by 490 publications

(116 citation statements)

References 11 publications

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“…Each organic (acidified) and bulk (unacidified) sample was analyzed for C stable isotope ratios (d 13 C) and content (% dry weight) using isotope ratio mass spectrometry at the University of Regina following Leavitt et al (2006). Sediment chronology was based on 210 Pb activity measured by gamma spectrometry using an Ortec highpurity germanium (HPGe) coaxial well photon detector system following standard procedures (Appleby et al 1986;Schelske et al 1994). In brief, 15 evenly spaced samples were selected from each core, freeze-dried (72 h, 0.1 Pa), and homogenized before transfer into preweighed polyethylene tubes (15 3 80 mm).…”

Section: Methodsmentioning

confidence: 99%

Magnitudes and controls of organic and inorganic carbon flux through a chain of hard‐water lakes on the northern Great Plains

Finlay

Leavitt

Patoine

et al. 2010

Limnology & Oceanography

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Whole-lake carbon (C) mass-balance budgets were constructed for a chain of six hard-water lakes to quantify the relative importance of organic carbon (OC) and inorganic carbon (IC) exchanges between atmosphere, water column, sediments, and rivers. Mean summer C fluxes were calculated for each lake during the ice-free periods (May to September) of 1995-2007 by measuring deposition of IC and OC in lake sediments, export of C to outflow rivers, lotic C influxes, and atmospheric exchange of CO 2 . Unlike soft-water lakes, IC in rivers accounted for 68.2-85.6% of total C (TC) influx to these hard-water lakes, CO 2 efflux accounted for 0-44.5% of total C export (median 2.8%), and sedimentation buried similar amounts of OC and IC. Deposition of C in sediments accounted for 1.8-61.7% of total export and was correlated to water residence time, while C efflux through rivers accounted for 32.6-98.2% of total export, mainly as IC (69.6-85.1% of TC). Unexpectedly, estimates of net ecosystem production based on OC mass balances suggested that all lakes were autotrophic (production . respiration) during summer, despite elevated dissolved organic carbon content (5.6-16.1 mg C L 21 ), pCO 2 values, and net CO 2 emissions to the atmosphere from three lakes. We conclude that C fluxes within and among these hard-water lakes are regulated by hydrologic inputs of dissolved IC rather than by lake metabolism, IC and OC pathways are only loosely coupled, and future climate variability will alter C fluxes in similar lakes mainly through regulation of mass transfer from land.

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Section: Methodsmentioning

confidence: 99%

Magnitudes and controls of organic and inorganic carbon flux through a chain of hard‐water lakes on the northern Great Plains

Finlay

Leavitt

Patoine

et al. 2010

Limnology & Oceanography

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“…210 Pb was determined via gamma emissions at 46.5 keV and 226 Ra by the 295 keV and 352 keV gamma rays emitted by its daughter isotope 214 Pb following 3 weeks storage in sealed containers to allow radioactive equilibration. 137 Cs and 241 Am were measured by their emissions at 662 keV and 59.5 keV (Appleby et al 1986). Absolute efficiencies of the detector were determined using calibrated sources and sediment samples of known activity, and corrections made for the effect of within-sample self absorption of low energy gamma rays (Appleby et al 1992).…”

Section: Data Acquisitionmentioning

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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“…The core was radiometrically dated using standard gamma assay procedures (Appleby et al, 1986;Appleby et al, 1992) and the chronology was calculated based on 210 Pb using the constant rate of supply model (Appleby & Oldfield, 1978). Sediment accumulation rates of 0.12-0.15 cm yr -1 were estimated for this core for the period ~1930-1970, and a rate of 0.12 cm yr -1 was assumed for the period prior to 1930.…”

Section: Historicalmentioning

confidence: 99%

Historical changes (1905–2005) in external phosphorus loads to Loch Leven, Scotland, UK

May¹,

Defew²,

Bennion³

et al. 2011

Loch Leven: 40 Years of Scientific Research

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This paper reviews historical changes in the total phosphorus (TP) inputs to Loch Leven, Scotland, UK. Data derived from palaeolimnological records suggest that inputs in the early 1900s were about 6 t TP y -1 (0.45 g TP m -2 y -1 ). By 1985, this had risen to about 20 t TP y -1 (1.5 g TP m -2 y -1 ) due to increases in runoff from agricultural land and discharges from point sources. By the late 1970s, increased TP inputs were causing serious degradation of lake water quality. Most noticeably, there had been an increase in cyanobacterial blooms. A catchment management plan was implemented in the early 1990s. This resulted in a 60% reduction in the annual TP input between 1985 (20 t TP y -1 /1.5 g TP m -2 y -1 ) and 1995 (8 t TP y -1 /0.6 g TP m -2 y -1 ). The main reduction was associated with better control of point source discharges, but attempts were also made to reduce inputs from diffuse sources. The reduction in external TP loading to the lake led to a marked decline in TP retention by the lake each year.3

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210Pb dating by low background gamma counting

Cited by 490 publications

References 11 publications

Magnitudes and controls of organic and inorganic carbon flux through a chain of hard‐water lakes on the northern Great Plains

Magnitudes and controls of organic and inorganic carbon flux through a chain of hard‐water lakes on the northern Great Plains

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

Historical changes (1905–2005) in external phosphorus loads to Loch Leven, Scotland, UK

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