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

作者：Stewart Gillian^*; Moran S Bradley; Lomas Michael W; Kelly Roger P

来源：Journal of Environmental Radioactivity, 2011, 102(5): 479-489.

DOI：10.1016/j.jenvrad.2010.09.011

• Flux proxies
• POC export
• Thorium
• Polonium
• Biological pump
• Bermuda Atlantic time-series

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 Th-234 and its parent U-238 has become widely used as a technique to measure particle export fluxes from surface ocean waters. Another radionuclide pair, Po-210 and Pb-210, can be used for the same purpose but has not been as widely adopted due to difficulty with accurately constraining the Po-210/Pb-210 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 Th-234/U-238 and Po-210/Pb-210 data from oligotrophic surface waters of the subtropical Northwest Atlantic and discuss their advantages and limitations. Vertical profiles of total and particle size-fractionated Po-210 and Th-234 activities, together with particulate organic carbon (POC) concentrations, were measured during three seasons at the Bermuda Atlantic Time-series Study (BATS) site. Both Po-210 and Th-234 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.

• 出版日期2011-5