Organic carbon fluxes in the Atlantic and the Southern Ocean: relationship to primary production compiled from satellite radiometer data

Fischer, Gerhard; Ratmeyer, Volker; Wefer, Gerold

doi:10.1016/s0967-0645(00)00013-8

Cited by 106 publications

(74 citation statements)

References 68 publications

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“…The Kerguelen Plateau annual POC export (98.2 ± 4.4 mmol m −2 yr −1 ) approaches the median global ocean POC export value comprising shallow and deep sediment traps (83 mmol m −2 yr −1 ; Lampitt and Antia, 1997), but is also close to values observed in HNLC areas of the POOZ (11-43 mmol m −2 yr −1 at 500 m; Fischer et al, 2000). Moreover, the magnitude of annual POC export measured at ∼ 300m on the Kerguelen Plateau is comparable to deep-ocean (> 2 km) POC fluxes measured from the iron-fertilized Crozet (60 mmol m −2 yr −1 ; Salter et al, 2012) and South Georgia blooms (180 mmol m −2 yr −1 ; Manno et al, 2015).…”

Section: Evidence For Significant Flux Attenuation Over the Kerguelensupporting

confidence: 66%

Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

et al. 2015

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Abstract.A sediment trap moored in the naturally ironfertilized Kerguelen Plateau in the Southern Ocean provided an annual record of particulate organic carbon and nitrogen fluxes at 289 m. At the trap deployment depth, current speeds were typically low ( ∼ 10 cm s −1 ) and primarily tidaldriven (M2 tidal component). Although advection was weak, the sediment trap may have been subject to hydrodynamical and biological (swimmer feeding on trap funnel) biases. Particulate organic carbon (POC) flux was generally low (< 0.5 mmol m −2 d −1 ), although two episodic export events (< 14 days) of 1.5 mmol m −2 d −1 were recorded. These increases in flux occurred with a 1-month time lag from peaks in surface chlorophyll and together accounted for approximately 40 % of the annual flux budget. The annual POC flux of 98.2 ± 4.4 mmol m −2 yr −1 was low considering the shallow deployment depth but comparable to independent estimates made at similar depths (∼ 300 m) over the plateau, and to deep-ocean (> 2 km) fluxes measured from similarly productive iron-fertilized blooms. Although undertrapping cannot be excluded in shallow moored sediment trap deployment, we hypothesize that grazing pressure, including mesozooplankton and mesopelagic fishes, may be responsible for the low POC flux beneath the base of the winter mixed layer. The importance of plankton community structure in controlling the temporal variability of export fluxes is addressed in a companion paper.

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Section: Evidence For Significant Flux Attenuation Over the Kerguelensupporting

confidence: 66%

Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

et al. 2015

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“…Neuer et al, 1997Neuer et al, , 2002. For a detailed description of currents velocities and directions and the discussion of trapping efficiencies see Fischer et al (1996a, site CB) and Fischer et al (2000Fischer et al ( , 2002, Atlantic and Southern Ocean).…”

Section: Sediment Trap Collections and Analysismentioning

confidence: 99%

Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

2009

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Abstract. The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opalrich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of Correspondence to: G. Fischer (gerhard.fischer@uni-bremen.de) 0.29 Tg per year down to 3000 m off the NW African upwelling region between 5 and 35 • N. Simple parameterisations of remineralisation and sinking rates in such models, however, limit their capability in reproducing the flux variation in the water column.

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“…In these areas, maps of chlorophyll measurements indicate enhanced productivity, which lends to confidence in the model. Even if there is no simple relationship between primary production and particle export, POC export is only expected where primary production is high (Buesseler, 1998;Fischer et al, 2000). Opal exports are low in the tropical and subtropical Atlantic and increase to about 4.5 mol/m 2 /year at about 55jS, 10jE.…”

Section: Experiments Imentioning

confidence: 99%

Particle fluxes in the ocean: comparison of sediment trap data with results from inverse modeling

Usbeck

Schlitzer

Fischer

et al. 2003

Journal of Marine Systems

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Biological production lowers the CO 2 concentrations in the surface layer of the ocean, and sinking detritus ''pumps'' nutrients and CO 2 into the deep ocean. Quantifying the efficiency of the biological pump is a prerequisite for global CO 2 budgets. Sediment traps are commonly used to directly measure the vertical particle flux; however, for logistical and financial reasons, traps cannot provide area-wide data sets. Moreover, it has been shown that sediment traps can under-or overestimate particle fluxes considerably. In this paper, we present a new technique to estimate the downward flux of particulate matter with an adjoint model. Hydrographic and nutrient data are used to calculate the mean ocean circulation together with parameters for particle fluxes using the AWI Adjoint Model for Oceanic Carbon Cycling (AAMOCC). The model is fitted to the property concentrations by systematically varying circulation, air -sea fluxes, export production and remineralization rates of particulate biogenic matter simultaneously. The deviations of model fluxes based on nutrient budgets from direct measurements with sediment traps yield an independent estimate of apparent trapping efficiencies. While consistent with hydrographic and nutrient data, model particle fluxes rarely agree with sediment trap data: (1) At shallow water depth ( V 1000 m), sediment trap fluxes are at the average 50% lower than model fluxes, which confirms flux calibrations using radionuclides; (2) in the very deep traps, model fluxes tend to be lower compared to data, which might be explained by lateral inputs into the traps. According to these model results, particle fluxes from the euphotic zone (EP) into mid water depth are considerably higher and the shallow loop of nutrient is more vigorous than would be derived from sediment trap data. Our results imply that fluxes as collected with sediment traps are inconsistent with model derived long-term mean particle fluxes based on nutrient budgets in the water column. In agreement with recent radionuclide studies, we conclude that reliable export flux estimates can only be obtained from sediment trap data if appropriate corrections are applied. D

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Organic carbon fluxes in the Atlantic and the Southern Ocean: relationship to primary production compiled from satellite radiometer data

Cited by 106 publications

References 68 publications

Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

Particle fluxes in the ocean: comparison of sediment trap data with results from inverse modeling

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