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Recent 210Pb, 137Cs and 241Am accumulation in an ombrotrophic peatland from Amsterdam Island (Southern Indian Ocean)

Li, Chuxian; Le Roux, Gaël; Sonke, Jeroen; van Beek, Pieter; Souhaut, Marc; Van der Putten, Nathalie LU and De Vleeschouwer, François (2017) In Journal of Environmental Radioactivity 175-176. p.164-169
Abstract

Over the past 50 years, 210Pb, 137Cs and 241Am have been abundantly used in reconstructing recent sediment and peat chronologies. The study of global aerosol-climate interaction is also partially depending on our understanding of 222Rn-210Pb cycling, as radionuclides are useful aerosol tracers. However, in comparison with the Northern Hemisphere, few data are available for these radionuclides in the Southern Hemisphere, especially in the South Indian Ocean. A peat core was collected in an ombrotrophic peatland from the remote Amsterdam Island (AMS) and was analyzed for 210Pb, 137Cs and 241Am radionuclides using an underground ultra-low background... (More)

Over the past 50 years, 210Pb, 137Cs and 241Am have been abundantly used in reconstructing recent sediment and peat chronologies. The study of global aerosol-climate interaction is also partially depending on our understanding of 222Rn-210Pb cycling, as radionuclides are useful aerosol tracers. However, in comparison with the Northern Hemisphere, few data are available for these radionuclides in the Southern Hemisphere, especially in the South Indian Ocean. A peat core was collected in an ombrotrophic peatland from the remote Amsterdam Island (AMS) and was analyzed for 210Pb, 137Cs and 241Am radionuclides using an underground ultra-low background gamma spectrometer. The 210Pb Constant Rate of Supply (CRS) model of peat accumulations is validated by peaks of artificial radionuclides (137Cs and 241Am) that are related to nuclear weapon tests. We compared the AMS 210Pb data with an updated 210Pb deposition database. The 210Pb flux of 98 ± 6 Bq·m−2·y−1 derived from the AMS core agrees with data from Madagascar and South Africa. The elevated flux observed at such a remote location may result from the enhanced 222Rn activity and frequent rainfall in AMS. This enhanced 222Rn activity itself may be explained by continental air masses passing over southern Africa and/or Madagascar. The 210Pb flux at AMS is higher than those derived from cores collected in coastal areas in Argentina and Chile, which are areas dominated by marine westerly winds with low 222Rn activities. We report a 137Cs inventory at AMS of 144 ± 13 Bq·m−2 (corrected to 1969). Our data thus contribute to the under-represented data coverage in the mid-latitudes of the Southern Hemisphere.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cs, Pb, Am, Peat, Radionuclides, Southern indian ocean
in
Journal of Environmental Radioactivity
volume
175-176
pages
6 pages
publisher
Elsevier
external identifiers
  • scopus:85019934127
  • wos:000404310100019
ISSN
0265-931X
DOI
10.1016/j.jenvrad.2017.05.004
language
English
LU publication?
yes
id
92437957-84bc-4ede-ab25-f00185f74702
date added to LUP
2017-06-14 11:23:27
date last changed
2017-09-18 11:41:01
@article{92437957-84bc-4ede-ab25-f00185f74702,
  abstract     = {<p>Over the past 50 years, <sup>210</sup>Pb, <sup>137</sup>Cs and <sup>241</sup>Am have been abundantly used in reconstructing recent sediment and peat chronologies. The study of global aerosol-climate interaction is also partially depending on our understanding of <sup>222</sup>Rn-<sup>210</sup>Pb cycling, as radionuclides are useful aerosol tracers. However, in comparison with the Northern Hemisphere, few data are available for these radionuclides in the Southern Hemisphere, especially in the South Indian Ocean. A peat core was collected in an ombrotrophic peatland from the remote Amsterdam Island (AMS) and was analyzed for <sup>210</sup>Pb, <sup>137</sup>Cs and <sup>241</sup>Am radionuclides using an underground ultra-low background gamma spectrometer. The <sup>210</sup>Pb Constant Rate of Supply (CRS) model of peat accumulations is validated by peaks of artificial radionuclides (<sup>137</sup>Cs and <sup>241</sup>Am) that are related to nuclear weapon tests. We compared the AMS <sup>210</sup>Pb data with an updated <sup>210</sup>Pb deposition database. The <sup>210</sup>Pb flux of 98 ± 6 Bq·m<sup>−2</sup>·y<sup>−1</sup> derived from the AMS core agrees with data from Madagascar and South Africa. The elevated flux observed at such a remote location may result from the enhanced <sup>222</sup>Rn activity and frequent rainfall in AMS. This enhanced <sup>222</sup>Rn activity itself may be explained by continental air masses passing over southern Africa and/or Madagascar. The <sup>210</sup>Pb flux at AMS is higher than those derived from cores collected in coastal areas in Argentina and Chile, which are areas dominated by marine westerly winds with low <sup>222</sup>Rn activities. We report a <sup>137</sup>Cs inventory at AMS of 144 ± 13 Bq·m<sup>−2</sup> (corrected to 1969). Our data thus contribute to the under-represented data coverage in the mid-latitudes of the Southern Hemisphere.</p>},
  author       = {Li, Chuxian and Le Roux, Gaël and Sonke, Jeroen and van Beek, Pieter and Souhaut, Marc and Van der Putten, Nathalie and De Vleeschouwer, François},
  issn         = {0265-931X},
  keyword      = {Cs,Pb,Am,Peat,Radionuclides,Southern indian ocean},
  language     = {eng},
  month        = {09},
  pages        = {164--169},
  publisher    = {Elsevier},
  series       = {Journal of Environmental Radioactivity},
  title        = {Recent <sup>210</sup>Pb, <sup>137</sup>Cs and <sup>241</sup>Am accumulation in an ombrotrophic peatland from Amsterdam Island (Southern Indian Ocean)},
  url          = {http://dx.doi.org/10.1016/j.jenvrad.2017.05.004},
  volume       = {175-176},
  year         = {2017},
}