Direct comparison of ²¹⁰Po, ²³⁴Th and POC particle-size distributions and export fluxes at the Bermuda Atlantic Time-series Study (BATS) site

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• 作者：Gillian Stewart^a ; ^{gstewart@qc.cuny.edu"" rel=""nofollow} ; S. Bradley Moran^b ; ^{moran@gso.uri.edu"" rel=""nofollow} ; Michael W. Lomas^c ; ^{Michael.Lomas@bios.edu"" rel=""nofollow} ; Roger P. Kelly^b ; ^{rokelly@gso.uri.edu"" rel=""nofollow}
• 关键词：Flux proxies ; POC export ; Thorium ; Polonium ; Biological pump ; Bermuda Atlantic time-series
• 刊名：Journal of Environmental Radioactivity
• 出版年：2011
• 出版时间：May 2011
• 年：2011
• 卷：102
• 期：5
• 页码：479-489
• 全文大小：711 K

文摘

Particle-reactive, naturally occurring radionuclides are useful tracers of the sinking flux of organic matter from the surface to the deep ocean. Since the Joint Global Ocean Flux Study (JGOFS) began in 1987, the disequilibrium between ²³⁴Th and its parent ²³⁸U has become widely used as a technique to measure particle export fluxes from surface ocean waters. Another radionuclide pair, ²¹⁰Po and ²¹⁰Pb, can be used for the same purpose but has not been as widely adopted due to difficulty with accurately constraining the ²¹⁰Po/²¹⁰Pb radiochemical balance in the ocean and because of the more time-consuming radiochemical procedures. Direct comparison of particle flux estimated in different ocean regions using these short-lived radionuclides is important in evaluating their utility and accuracy as tracers of particle flux. In this paper, we present paired ²³⁴Th/²³⁸U and ²¹⁰Po/²¹⁰Pb data from oligotrophic surface waters of the subtropical Northwest Atlantic and discuss their advantages and limitations. Vertical profiles of total and particle size-fractionated ²¹⁰Po and ²³⁴Th activities, together with particulate organic carbon (POC) concentrations, were measured during three seasons at the Bermuda Atlantic Time-series Study (BATS) site. Both ²¹⁰Po and ²³⁴Th reasonably predict sinking POC flux caught in sediment traps, and each tracer provides unique information about the magnitude and efficiency of the ocean's biological pump.