Recent 210Pb, 137Cs and 241Am accumulation in an ombrotrophic peatland from Amsterdam Island (Southern Indian Ocean). (September 2017)

• Record Type: Journal Article
• Authors: Li, Chuxian; Le Roux, Gaël; Sonke, Jeroen; van Beek, Pieter; Souhaut, Marc; Van der Putten, Nathalie; De Vleeschouwer, François
• Is Part Of: Journal of environmental radioactivity. Volume 175/176(2017)
• Page Start: 164
• Page End: 169
• Publication Date: 2017-09
• Subjects: Radionuclides -- 210Pb -- 137Cs -- 241Am -- Peat -- Southern indian ocean; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2017.05.004
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: Over the past 50 years, 210 Pb, 137 Cs and 241 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 222 Rn- 210 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 210 Pb, 137 Cs and 241 Am radionuclides using an underground ultra-low background gamma spectrometer. The 210 Pb Constant Rate of Supply (CRS) model of peat accumulations is validated by peaks of artificial radionuclides ( 137 Cs and 241 Am) that are related to nuclear weapon tests. We compared the AMS 210 Pb data with an updated 210 Pb deposition database. The 210 Pb 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 222 Rn activity and frequent rainfall in AMS. This enhanced 222 Rn activity itself may be explained by continental air masses passing over southern Africa and/or Madagascar. The 210 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 222 Rn activities. We report a 137 Cs 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. Highlights: First peat record of artificial radionuclides ( 137 Cs and 241 Am) in the Southern Indian Ocean. Updated world 210 Pb database with 47 new entries from the recent literature. 210 Pb inventory found in the peat core from Amsterdam Island is similar to those from South Africa and Madagascar.