Seasonal distributions and fluxes of 210Pb and 210Po in the northern South China Sea

C.-L. Wei, M.-C. Yi, S.-Y. Lin, L.-S. Wen, W.-H. Lee
2014 Biogeosciences  
<p><strong>Abstract.</strong> Vertical distributions of dissolved and particulate <sup>210</sup>Pb and <sup>210</sup>Po in the water column at the SouthEast Asian Time-series Study (SEATS, 18°00´ N and 116°00´ E) station in the northern South China Sea were determined from four cruises between January 2007 and June 2008. A large deficiency of <sup>210</sup>Pb, 379 ± 43 × 10<sup>3</sup> dpm m<sup>−2</sup>, from the secular equilibrium was found within the 3500 m water column. On the other hand,
more » ... smaller deficiency of <sup>210</sup>Po, 100 ± 21 × 10<sup>3</sup> dpm m<sup>−2</sup>, relative to <sup>210</sup>Pb was found in the water column. Time-series data showed insignificant temporal variability of the <sup>210</sup>Pb and <sup>210</sup>Po profiles. To balance these deficiencies, the removal fluxes for <sup>210</sup>Pb and <sup>210</sup>Po via particle settling ranging from 45 to 51 dpm m<sup>−2</sup>d<sup>−1</sup> and from 481 to 567 dpm m<sup>−2</sup>d<sup>−1</sup>, respectively, are expected at 3500 m. The <sup>210</sup>Pb removal flux is comparable with, whereas the <sup>210</sup>Po removal flux is much higher than, the flux directly measured by moored sediment traps. The discrepancy between the modeled <sup>210</sup>Po flux and the measured flux suggests that sporadic events that enhance <sup>210</sup>Po removal via sinking ballast may occur in the water column at the site.</p>
doi:10.5194/bg-11-6813-2014 fatcat:whjg37xpzvcm7o47icooyycani