Sediment tracing and environmental history for two small catchments, Karoo Uplands, South Africa

Foster, Ian D L; Boardman, John; Keay-Bright, James

doi:10.1016/j.geomorph.2007.01.011

Cited by 109 publications

(104 citation statements)

References 20 publications

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“…Independent analysis using mineral magnetism, sediment colour and geochemistry (e.g. Foster et al, 2007) confirm this interpretation suggesting that gully sidewalls are not significant sediment sources but that the gullies themselves increase connectivity at the landscape scale by delivering sediment from more distal topsoil sources. 137 Cs profiles in the farm dams rarely mirror those of atmospheric fallout and have often proved equivocal in determining the peak in atmospheric fallout in 1965, unlike their Northern Hemisphere counterparts (see e.g.…”

Section: Cs In Farm Dam Sedimentsmentioning

confidence: 81%

“…All radionuclide data reported here and elsewhere have been obtained using EG&G Ortec Hyper-Pure Ge detectors in a "well" configuration (40 mm deep; 11 mm diameter), located at Coventry and Northampton Universities and operated at liquid N temperatures. Samples were screened to < 125 µm diameter (to match previous protocols; see Foster et al, 2007) by dry sieving prior to analysis and count times were typically in excess of 2 days in order to reduce counting errors to ca. 5 % or less.…”

Section: Study Area Materials and Methodsmentioning

confidence: 99%

“…Additional chronological markers have been established from the presence of thin layers of fine gravels deposited in dams by high magnitude floods whose timeframe has been established from local rainfall records (e.g. Foster et al, 2007). Multiple sediment cores are required to quantify the spatial variability in deposition and estimate the volume of sediment deposited over different timescales.…”

Section: D L Foster Et Al: the Potential For Gamma-emitting Radmentioning

confidence: 99%

“…The advantage in this approach lies in significantly reducing the number of 137 Cs determinations likely to be needed at each site, making it possible to develop a large database at relatively low cost. Targeted full sediment yield reconstructions in carefully selected areas could take sediment yield estimates back to the early 20th century and would provide targets that could be used to demonstrate reductions needed to achieve a "baseline state" (see Foster et al, 2011).…”

Section: D L Foster Et Al: the Potential For Gamma-emitting Radmentioning

confidence: 99%

“…In order to investigate other potential controls, such as the co-precipitation of 137 Cs with metal oxides or nutrients on particle surface coatings, concentrations of Fe, Mn and P were determined on microwave digested sediment samples using ICP-OES (Foster et al, 2007) but, again, no statistically significant correlations were found between metal or nutrient content and 137 Cs activity. Statistically significant correlations, with r 2 values generally above 90 %, were produced for several mineral magnetic susceptibility and remanence properties and, more surprisingly, with loss on ignition (LOI) (Fig.…”

Section: The Good Hope Conundrummentioning

confidence: 99%

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The potential for gamma-emitting radionuclides to contribute to an understanding of erosion processes in South Africa

et al. 2017

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Abstract. Several research projects undertaken by the authors and others over the last 14 years have used fallout and geogenic radionuclides for understanding erosion processes and sediment yield dynamics in South Africa over the last 100-200 years as European settlers colonised the interior plains and plateaux of the country and imported new livestock and farming techniques to the region. These projects have used two fallout radionuclides ( 210 Pb and 137 Cs) to date sediments accumulating in reservoirs, farm dams, wetlands, alluvial fans and floodouts and have used other fallout nuclides ( 7 Be) and long-lived geogenic radionuclides (e.g. 40 K, 235 U) as part of a composite fingerprint exploring contemporary sediment sources and changes to sources through time. While successful in many parts of the world, applying these techniques in Southern Africa has posed a number of challenges often not encountered elsewhere. Here we explore some of the benefits and challenges in using gamma-emitting radionuclides, especially 137 Cs, in these landscapes. Benefits include the potential for discriminating gully sidewall from topsoil sources, which has helped to identify contemporary gully systems as sediment conduits, rather than sources, and for providing a time-synchronous marker horizon in a range of sedimentary environments that has helped to develop robust chronologies. Challenges include the spatial variability in soil cover on steep rocky hillslopes, which is likely to challenge assumptions about the uniformity of initial fallout nuclide distribution, the paucity of stable (non-eroding) sites in order to estimate atmospheric fallout inventories, and the limited success of 210 Pb dating in some rapidly accumulating high altitude catchments where sediments often comprise significant amounts of sand and gravel. Despite these challenges we present evidence suggesting that the use of gamma-emitting radionuclides can make a significant contribution to our understanding of erosion processes and sediment yield dynamics. Future research highlighted in the conclusion will try to address current challenges and outline new projects established to address them more fully.

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Section: Cs In Farm Dam Sedimentsmentioning

confidence: 81%

Section: Study Area Materials and Methodsmentioning

confidence: 99%

Section: D L Foster Et Al: the Potential For Gamma-emitting Radmentioning

confidence: 99%

Section: D L Foster Et Al: the Potential For Gamma-emitting Radmentioning

confidence: 99%

Section: The Good Hope Conundrummentioning

confidence: 99%

See 3 more Smart Citations