Global database of surface ocean particulate organic carbon export fluxes diagnosed from the &amp;lt;sup&amp;gt;234&amp;lt;/sup&amp;gt;Th technique

Moigne, Frédéric A.C. Le; Henson, Stephanie A.; Sanders, Richard J.; Madsen, E.

doi:10.5194/essd-5-295-2013

Cited by 69 publications

(99 citation statements)

References 82 publications

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“…1. Study area and sampled stations for 234 Th, POC and PON analyses. C represents the central station, which was occupied 7 times: C91, C98, C99, C114, C128, C136, C140.…”

Section: Study Areamentioning

confidence: 99%

“…Time-series measurements of 234 Th, POC, PON, Chl-a, other pigments and NPP were carried out at a station located in the centre of the study area at 51.21°S 12.67°W (hereafter "central station", indicated by a 'C' in front of the station number). The location and sampling dates of the stations sampled for 234 Th, POC and PON fluxes are given in Fig. 1 and Table 1.…”

Section: Study Areamentioning

confidence: 99%

“…The sampling was carried out to study a massive bloom with high spatial and temporal resolution over an area of about 8000 km 2 located between the Antarctic Polar Front (APF) and the Southern Polar Front (SPF; Leach et al, 2017 and. Time-series measurements of 234 Th, POC, PON, Chl-a, other pigments and NPP were carried out at a station located in the centre of the study area at 51.21°S 12.67°W (hereafter "central station", indicated by a 'C' in front of the station number). The location and sampling dates of the stations sampled for 234 Th, POC and PON fluxes are given in Fig.…”

Section: Study Areamentioning

confidence: 99%

“…Buesseler et al, 1992;Rutgers van der Loeff et al, 1997). A deficit of 234 Th with respect to its parent 238 U is typically found in the upper ocean. Once the 234 Th downward flux at a specific depth is quantified, this flux can be converted to POC and particulate organic nitrogen (PON) fluxes by determining the POC/ 234 Th and PON/ 234 Th ratios, respectively, in sinking particles Cochran and Masqué, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Puigcorbé et al, 2015;Turner, 2015). We used the disequilibrium between the natural radionuclides 234 Th and 238 U to determine the export fluxes of POC and PON in parallel with the use of surface-tethered drifting sediment traps. Export fluxes were related to the evolution of chlorophyll a (Chl-a) and POC concentrations in the water column, as well as to pigments in sinking particles, following the decline of the bloom during three weeks.…”

Section: Introductionmentioning

confidence: 99%

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High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Roca‐Martí

Puigcorbé

Iversen

et al. 2017

Deep Sea Research Part II: Topical Studies in Oceanography

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a b s t r a c tCarbon fixation by phytoplankton plays a key role in the uptake of atmospheric CO 2 in the Southern Ocean. Yet, it still remains unclear how efficiently the particulate organic carbon (POC) is exported and transferred from ocean surface waters to depth during phytoplankton blooms. In addition, little is known about the processes that control the flux attenuation within the upper twilight zone. Here, we present results of downward POC and particulate organic nitrogen fluxes during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean in summer 2012. We used thorium-234 ( 234 Th) as a particle tracer in combination with drifting sediment traps (ST). Their simultaneous use evidenced a sustained high export rate of 234 Th at 100 m depth in the weeks prior to and during the sampling period. The entire study area, of approximately 8000 km 2 , showed similar vertical export fluxes in spite of the heterogeneity in phytoplankton standing stocks and productivity, indicating a decoupling between production and export. The POC fluxes at 100 m were high, averaging 26 715 mmol C m À 2 d À 1 , although the strength of the biological pump was generally low. Only o 20% of the daily primary production reached 100 m, presumably due to an active recycling of carbon and nutrients. Pigment analyses indicated that direct sinking of diatoms likely caused the high POC transfer efficiencies ( $ 60%) observed between 100 and 300 m, although faecal pellets and transport of POC linked to zooplankton vertical migration might have also contributed to downward fluxes.

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“…1. Study area and sampled stations for 234 Th, POC and PON analyses. C represents the central station, which was occupied 7 times: C91, C98, C99, C114, C128, C136, C140.…”

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Roca‐Martí

Puigcorbé

Iversen

et al. 2017

Deep Sea Research Part II: Topical Studies in Oceanography

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Variability in efficiency of particulate organic carbon export: A model study

Henson

Yool

Sanders

2015

Global Biogeochemical Cycles

115

137

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The flux of organic carbon from the surface ocean to mesopelagic depths is a key component of the global carbon cycle and is ultimately derived from primary production (PP) by phytoplankton. Only a small fraction of organic carbon produced by PP is exported from the upper ocean, referred to as the export efficiency (herein e-ratio). Limited observations of the e-ratio are available, and there is thus considerable interest in using remotely sensed parameters such as sea surface temperature to extrapolate local estimates to global annual export flux. Currently, there are large discrepancies between export estimates derived in this way; one possible explanation is spatial or temporal sampling bias in the observations. Here we examine global patterns in the spatial and seasonal variability in e-ratio and the subsequent effect on export estimates using a high-resolution global biogeochemical model. The model used here represents export as separate slow-and fast-sinking detrital material whose remineralization is respectively temperature dependent and a function of ballasting minerals. We find that both temperature and the fraction of export carried by slow-sinking particles are factors in determining e-ratio, suggesting that current empirical algorithms for e-ratio that only consider temperature are overly simple. We quantify the temporal lag between PP and export, which is greatest in regions of strong variability in PP where seasonal decoupling can result in large e-ratio variability. Extrapolating global export estimates from instantaneous measurements of e-ratio is strongly affected by seasonal variability and can result in errors in estimated export of up to ±60%.

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Observations and modeling of slow‐sinking particles in the twilight zone

Villa-Alfageme

Soto

Moigne

et al. 2014

Global Biogeochemical Cycles

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The biological carbon pump (BCP) transfers carbon from the surface ocean into the oceans' interior, mainly in the form of sinking particles with an organic component, and thereby keeps atmospheric CO 2 at significantly lower levels than if the oceans were abiotic. The depth at which these sinking particles are remineralized is a key control over atmospheric CO 2 . Particle sinking speed is likely to be a critical parameter over remineralization depth. Carbon export is usually controlled by large, rapidly sinking particles (>150 m·d À1 ); however, under some circumstances sinking velocity distributions are strongly bimodal with a significant fraction of total flux being carried by slowly (<10 m·d À1 ) sinking particles. Therefore, there is an interest in determining sinking particle velocities and their variations with depth, as well as in understanding the interplay between sinking velocity distributions and carbon export. Here, we use profiles of total and particulate concentrations of the naturally occurring radionuclide pair 210 Pb from the Porcupine Abyssal Plain (PAP) site (48°N, 16.5°W) to estimate depth variation in particle sinking speed using a one-box model and inverse techniques. Average sinking speeds increase from 60 ± 30 m·d À1 at 50 m, to 75 ± 25 m·d À1 and 90 ± 20 m·d À1 at 150 and 500 m.Furthermore, a sensitivity analysis suggests that at the PAP site the measured 210Po profiles are inconsistent with the usually assumed sinking velocities of 200 m·d À1. We hypothesize that a trend of increasing velocity with depth might be caused by a gradual loss of slow-sinking material with depth, a factor with significant implications for regional carbon budgets.

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Global database of surface ocean particulate organic carbon export fluxes diagnosed from the <sup>234</sup>Th technique

Cited by 69 publications

References 82 publications

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Variability in efficiency of particulate organic carbon export: A model study

Observations and modeling of slow‐sinking particles in the twilight zone

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