Sediment trap and in-situ pump size-fractionated POC/234Th ratios in the Mediterranean Sea and Northwest Atlantic: Implications for POC export

Impact of the natural Fe-fertilization on the magnitude, stoichiometry and efficiency of particulate biogenic silica, nitrogen and iron export fluxes

“…4). Disagreements in POC: 234 Th ratios between P-trap and ISP methods have been observed elsewhere, with differences ranging between a factor 2 and 6 (Bacon et al, 1996;Benitez-Nelson et al, 2001;Buesseler et al, 1995Buesseler et al, , 1992Lepore et al, 2009;Murray et al, 1996;Puigcorbé et al, 2015;Stewart et al, 2007). In this study, the largest difference between P-trap and ISP was observed at E-1 for BSi: 234 Th ratios (factor of 5.4).…”

The influence of particle concentration and composition on the fractionation of 210Po and 210Pb along the North Atlantic GEOTRACES transect GA03

“…While we find remineralization (low AOU as a proxy 472 for "freshness") was an important driver of variation in the small particles, it was not 473 significant for the large particles. The difference in our results, specifically the lack of 474 20 correlation between AOU and PC scores for large particles, may be caused by differences 475 between the particulate material collected by sediment traps and those collected by in situ 476 pumps (Abramson et al, 2010;Lepore et al, 2009). This concept, however, that degradation 477 and sinking speed can cause some variation of composition within the small and large 478 particles, was confirmed by our result that the depth of the sample is correlated to the 479 distribution along PC2 in the large fraction (which explains 30% of the variation in the 480 particle composition), and along PC3 in the small fraction (12 % of the variation).…”

A method for the sequential measurement of yttrium-90 and thorium-234 and their application to the study of rapid particle dynamics in aquatic systems

“…With respect to 234 Th, 90 Y might offer several advantages. In an offshore environment, fluxes derived from 90 Y disequilibria might more closely match the timescale of particle collection in a sediment trap (Cochran et al 2009;Buesseler et al 2009;Lepore et al 2009). In shallow, nearshore areas, large particle fluxes are less likely to overwhelm the rate of 90 Y production; and sediment resuspension events-depending on their frequency-are less likely to dampen the true estimate of gross particle removal.…”