Export and remineralization of POM in the Southern Ocean and the South China Sea estimated from 210Po/210Pb disequilibria

Particle-reactive radionuclides (<sup>234</sup>Th, <sup>210</sup>Pb, <sup>210</sup>) as tracers for the estimation of export production in the South China Sea

“…Except for the first cruise (ORI-812), from which only 234 Th activity in unfiltered seawater was measured, filtration of large-volume seawater for the determination of 234 Th, 210 Pb, and 210 Po activities in filtrate and particles was carried out for all samples. At each sampling depth, 40 l seawater was collected and divided into one 20 l and two 10 l subsamples.…”

“…biochemical modeling (Liu et al, 2002), carbon budgeting (Chou et al, 2006), and new productivity measurements (Chen and Chen, 2005;Chen et al, 2004), the magnitude of POC export from the euphotic zone has never directly been measured. Previously, short-lived particle-reactive radionuclides, 234 Th (t 1/2 =24.1 d), 210 Pb (t 1/2 = 22.4 a), and 210 Po (t 1/2 = 138 d), have been found to be very useful for the esti3794 C.-L. Wei et al: Export production estimated by particle-reactive radionuclides in the South China Sea 234 Th has been widely used as a powerful tracer for POC and provided estimates of the export production (see review of Buesseler, 1998). There is only a few studies that used 210 Pb to estimate the export production in the ocean, although a strong correlation of 210 Pb removal with the POC flux was previously demonstrated (Moore and Dymond, 1988).…”

“…Previously, short-lived particle-reactive radionuclides, 234 Th (t 1/2 =24.1 d), 210 Pb (t 1/2 = 22.4 a), and 210 Po (t 1/2 = 138 d), have been found to be very useful for the esti3794 C.-L. Wei et al: Export production estimated by particle-reactive radionuclides in the South China Sea 234 Th has been widely used as a powerful tracer for POC and provided estimates of the export production (see review of Buesseler, 1998). There is only a few studies that used 210 Pb to estimate the export production in the ocean, although a strong correlation of 210 Pb removal with the POC flux was previously demonstrated (Moore and Dymond, 1988). On the other hand, due to its high affinity with biological particles (Cherry et al, 1975), 210 Po is also used as a powerful tracer for particulate matter sinking out of surface ocean (Murray et al, 2005;Friedrich and Rutgers van der Loeff, 2002;Verdeny et al, 2009;Kim and Church, 2001;Buesseler et al, 2008).…”

“…There is only a few studies that used 210 Pb to estimate the export production in the ocean, although a strong correlation of 210 Pb removal with the POC flux was previously demonstrated (Moore and Dymond, 1988). On the other hand, due to its high affinity with biological particles (Cherry et al, 1975), 210 Po is also used as a powerful tracer for particulate matter sinking out of surface ocean (Murray et al, 2005;Friedrich and Rutgers van der Loeff, 2002;Verdeny et al, 2009;Kim and Church, 2001;Buesseler et al, 2008).…”

“…(2) to compare the geochemical behavior of 234 Th, 210 Pb, and 210 Po, and Eq. (3) to estimate the export flux of POC, PIC, and PN by 234 Th/ 238 U, 210 Po/ 210 Pb, and 210 Pb/ 226 Ra disequilibria in the euphotic layer of the northern South China Sea.…”