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

Ian D.L Foster (Corresponding Author), John Boardman, Adrian L. Collins, Ruth Copeland-Philips, Niklaus J. Kuhn, Tim M. Mighall, Simon Pulley, Kate Rowntree

Research output: Contribution to journalArticle

3 Citations (Scopus)
4 Downloads (Pure)

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
(210Pb and 137Cs) to date sediments accumulating in reservoirs, farm dams, wetlands, alluvial fans and
floodouts and have used other fallout nuclides (7Be) and long-lived geogenic radionuclides (e.g. 40K, 235U) 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 137Cs, 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 210Pb 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.
Original languageEnglish
Pages (from-to)29-34
Number of pages6
JournalProceedings of the International Association of Hydrological Sciences
Volume375
DOIs
Publication statusPublished - 3 Mar 2017

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radionuclide
erosion
fallout
sediment yield
gully
alluvial fan
sand and gravel
hillslope
sediment
topsoil
chronology
livestock
dam
wetland
Africa
plateau
farm
catchment
project

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The potential for gamma-emitting radionuclides to contribute to an understanding of erosion processes in South Africa. / Foster, Ian D.L (Corresponding Author); Boardman, John; Collins, Adrian L. ; Copeland-Philips, Ruth ; Kuhn, Niklaus J. ; Mighall, Tim M.; Pulley, Simon ; Rowntree, Kate.

In: Proceedings of the International Association of Hydrological Sciences , Vol. 375, 03.03.2017, p. 29-34.

Research output: Contribution to journalArticle

Foster, Ian D.L ; Boardman, John ; Collins, Adrian L. ; Copeland-Philips, Ruth ; Kuhn, Niklaus J. ; Mighall, Tim M. ; Pulley, Simon ; Rowntree, Kate. / The potential for gamma-emitting radionuclides to contribute to an understanding of erosion processes in South Africa. In: Proceedings of the International Association of Hydrological Sciences . 2017 ; Vol. 375. pp. 29-34.
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abstract = "Several research projects undertaken by the authors and others over the last 14 years have used falloutand geogenic radionuclides for understanding erosion processes and sediment yield dynamics in South Africaover the last 100–200 years as European settlers colonised the interior plains and plateaux of the country andimported new livestock and farming techniques to the region. These projects have used two fallout radionuclides(210Pb and 137Cs) to date sediments accumulating in reservoirs, farm dams, wetlands, alluvial fans andfloodouts and have used other fallout nuclides (7Be) and long-lived geogenic radionuclides (e.g. 40K, 235U) aspart 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 numberof challenges often not encountered elsewhere. Here we explore some of the benefits and challenges in usinggamma-emitting radionuclides, especially 137Cs, in these landscapes. Benefits include the potential for discriminatinggully sidewall from topsoil sources, which has helped to identify contemporary gully systems as sedimentconduits, rather than sources, and for providing a time-synchronous marker horizon in a range of sedimentaryenvironments that has helped to develop robust chronologies. Challenges include the spatial variability in soilcover on steep rocky hillslopes, which is likely to challenge assumptions about the uniformity of initial falloutnuclide distribution, the paucity of stable (non-eroding) sites in order to estimate atmospheric fallout inventories,and the limited success of 210Pb dating in some rapidly accumulating high altitude catchments where sedimentsoften comprise significant amounts of sand and gravel. Despite these challenges we present evidence suggestingthat the use of gamma-emitting radionuclides can make a significant contribution to our understanding of erosionprocesses and sediment yield dynamics. Future research highlighted in the conclusion will try to address currentchallenges and outline new projects established to address them more fully.",
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AU - Boardman, John

AU - Collins, Adrian L.

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AU - Kuhn, Niklaus J.

AU - Mighall, Tim M.

AU - Pulley, Simon

AU - Rowntree, Kate

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AB - Several research projects undertaken by the authors and others over the last 14 years have used falloutand geogenic radionuclides for understanding erosion processes and sediment yield dynamics in South Africaover the last 100–200 years as European settlers colonised the interior plains and plateaux of the country andimported new livestock and farming techniques to the region. These projects have used two fallout radionuclides(210Pb and 137Cs) to date sediments accumulating in reservoirs, farm dams, wetlands, alluvial fans andfloodouts and have used other fallout nuclides (7Be) and long-lived geogenic radionuclides (e.g. 40K, 235U) aspart 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 numberof challenges often not encountered elsewhere. Here we explore some of the benefits and challenges in usinggamma-emitting radionuclides, especially 137Cs, in these landscapes. Benefits include the potential for discriminatinggully sidewall from topsoil sources, which has helped to identify contemporary gully systems as sedimentconduits, rather than sources, and for providing a time-synchronous marker horizon in a range of sedimentaryenvironments that has helped to develop robust chronologies. Challenges include the spatial variability in soilcover on steep rocky hillslopes, which is likely to challenge assumptions about the uniformity of initial falloutnuclide distribution, the paucity of stable (non-eroding) sites in order to estimate atmospheric fallout inventories,and the limited success of 210Pb dating in some rapidly accumulating high altitude catchments where sedimentsoften comprise significant amounts of sand and gravel. Despite these challenges we present evidence suggestingthat the use of gamma-emitting radionuclides can make a significant contribution to our understanding of erosionprocesses and sediment yield dynamics. Future research highlighted in the conclusion will try to address currentchallenges and outline new projects established to address them more fully.

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JO - Proceedings of the International Association of Hydrological Sciences

JF - Proceedings of the International Association of Hydrological Sciences

SN - 2199-899X

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