Direct comparison of 210Po, 234Th and POC particle-size distributions and export fluxes at the Bermuda Atlantic Time-series Study (BATS) site.
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 (234)Th and its parent (238)U has become widely used as a technique to measure particle export fluxes from surface ocean waters. Another radionuclide pair, (210)Po and (210)Pb, can be used for the same purpose but has not been as widely adopted due to difficulty with accurately constraining the (210)Po/(210)Pb 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 (234)Th/(238)U and (210)Po/(210)Pb data from oligotrophic surface waters of the subtropical Northwest Atlantic and discuss their advantages and limitations. Vertical profiles of total and particle size-fractionated (210)Po and (234)Th activities, together with particulate organic carbon (POC) concentrations, were measured during three seasons at the Bermuda Atlantic Time-series Study (BATS) site. Both (210)Po and (234)Th 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.
Queens College, CUNY Flushing, NY 11367, USA. gstewart@qc.cuny.edu
Gillian
G
Stewart
S Bradley
SB
Moran
Michael W
MW
Lomas
Roger P
RP
Kelly
D001267:Atlantic Ocean; D001605:Bermuda; D002244:Carbon / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D007856:Lead Radioisotopes / Q000032:analysis; D009930:Organic Chemicals / Q000032:analysis*; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D011059:Polonium / Q000032:analysis; D011868:Radioisotopes / Q000032:analysis*; D013910:Thorium / Q000032:analysis; D013997:Time Factors; D014501:Uranium / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
D007856:Lead Radioisotopes; D009930:Organic Chemicals; D052638:Particulate Matter; D011868:Radioisotopes; D014874:Water Pollutants, Chemical; D014501:Uranium; D013910:Thorium; D002244:Carbon; D011059:Polonium