Factors controlling the flux of organic carbon to the bathypelagic zone of the ocean

Abstract

[1] Particle fluxes measured with time series sediment traps deployed below 2000 m at 68 sites in the world ocean are combined with satellite-derived estimates of export production from the overlying water to assess the factors affecting the transfer of particulate organic matter from surface to deep water. Multiple linear regression is used to derive an algorithm suggesting that the transfer efficiency of organic carbon, defined as the settling flux of organic carbon normalized to export production, increases with the flux of carbonate and decreases with water depth and seasonality. The algorithm predicts >80% of the organic carbon transfer efficiency variability in diverse oceanic regions. The influence of the carbonate flux suggests that the ballasting effect of this biogenic mineral may be an important factor promoting export of organic carbon to the deep sea by increasing the density of settling particles. However, the lack of a similar effect for biogenic opal suggests that factors other than particle density also play a role. The adverse effect of increasing seasonality on the transfer efficiency of carbon to the deep sea is tentatively attributed to greater biodegradability of organic matter exported during bloom events. In high latitude opal-dominated regions with high f-ratios and seasonality, while a higher fraction of net production is exported, a higher fraction of the exported organic matter is remineralized before reaching bathypelagic depths. On the other hand, in warm, low latitude, carbonate-dominated regions with low f-ratios and seasonality, a higher fraction of the exported organic matter sinks to the deep sea.

Controls on mesopelagic particle fluxes in the Sub-Antarctic and Polar Frontal Zones in the Southern Ocean south of Australia in summer—Perspectives from free-drifting sediment traps

“…This may have contributed to the high flux attenuation with depth that was found at P2. Regarding the ballasting effect, the presence of calcium carbonate and silica minerals have been demonstrated to influence POC export to traps in the ocean interior (Armstrong et al, 2002;Francois et al, 2002;Klaas and Archer, 2002), although their role may be less relevant closer to the ocean surface (Passow, 2004;Trull et al, 2008). Therefore, the highest CaCO 3 flux at P1 might have enhanced export as previously suggested for this region (Cardinal et al, 2005).…”

“…Globally distributed deep ocean sediment trap programs have revealed some of the factors that correlate with high POC flux, including the presence of ballast minerals (primarily autochthonous biogenic carbonates and silica, and secondarily allochthonous lithogenic particles) and the occurrence of strong seasonality (Lampitt and Antia, 1997;Armstrong et al, 2002;Francois et al, 2002;Klaas and Archer, 2002;Lutz et al, 2002Lutz et al, , 2007. However the importance of minerals is less clear at mesopelagic depths, where POC dominates particle contents to a much greater degree, particle size, and porosity are strong influences on sinking rates (Alldredge and Gotschalk, 1988;Alldredge, 1998;Passow, 2004;Stemmann et al, 2004;De La Rocha and Passow, 2007), and where the vast majority of flux attenuation occurs (Martin et al, 1987;Buesseler et al, 2007a).…”

VERTIGO (VERtical Transport In the Global Ocean): A study of particle sources and flux attenuation in the North Pacific

“…Thus physical controls on the depth of the euphotic zone and surface mixed layer plus the extent of upper ocean ventilation can affect the export of particulate carbon . The extent of POC and particulate inorganic carbon (PIC) partitioning on sinking particles with depth is also critical for understanding ocean C uptake, since photosynthesis and the production of POC decreases surface ocean pCO 2 , while production of calcium carbonate (calcite and aragonite), which are the main forms of PIC, would ultimately increase pCO 2 (Holligan et al, 1993;Antia et al, 1999;Francois et al, 2002;Berelson et al, 2007).…”

Paleoceanography of the southern Agulhas Plateau during the last 150 ka: Inferences from benthic foraminiferal assemblages and multispecies epifaunal carbon isotopes

“…It has been suggested that it is the seasonality of primary production that determines the export flux of organic carbon (C org ) to the deep ocean. Initially it was assumed that export production is higher in strongly seasonal systems [Berger and Wefer, 1990], but this was not consistent with sediment trap data [Lampitt and Antia, 1997] and it rather appears now that a higher fraction of the exported organic matter sinks in regions with low seasonality [Francois et al, 2002]. In areas characterized by high seasonality of primary production, organic particles rapidly sink and produce a fluffy layer of phytodetrital aggregates on the seafloor [Beaulieu, 2002] which provide a major source of highquality food for benthic organisms, including benthic foraminifera.…”