Seasonal variability of particle flux in the Weddell Sea and its relation to ice cover

Fischer, Gerhard; Fütterer, Dieter K; Gersonde, Rainer; Honjo, Susumu; Ostermann, Dorinda R; Wefer, Gerold

doi:10.1038/335426a0

Cited by 244 publications

(82 citation statements)

References 14 publications

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“…The data from SFB261 are mostly published (Fischer et al, 1988(Fischer et al, , 1996a(Fischer et al, ,b, 2000Fischer and Wefer, 1996;Wefer and Fischer, 1991). For the comparison with model shows high seasonality with high particle fluxes from January to the end of March and low fluxes otherwise.…”

Section: Sediment Trap Datamentioning

confidence: 99%

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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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Section: Sediment Trap Datamentioning

confidence: 99%

“…WS1 (Weddell Sea) shows a seasonal signal with high particle fluxes in February. The mean particle flux was taken from Fischer et al (1988). BATS traps were deployed for up to 2 years.…”

Section: Sediment Trap Datamentioning

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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“…The Wrst is the formation and dissolution of CaCO 3 by calcareous plankton in the surface layer. In the Weddell Sea the abundance of calcareous plankton in the surface layer and in sediment traps below it is relatively small (Fischer et al 1988)-indeed, the Southern Ocean phytoplankton population is dominated by siliceous species, mainly diatoms. Chemical evidence for this may be provided by alkalinity data because CaCO 3 changes are reXected in changes of the alkalinity.…”

Section: Estimate Of Net Community Productionmentioning

confidence: 99%

Whole season net community production in the Weddell Sea

et al. 2007

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Depletions of total CO 2 , nitrate, phosphate and silicate in the surface layer were calculated for cruise ANT XXII/3 with FS Polarstern in March 2005 for estimating the annual net community production. East-west across the Weddell Sea the variation of all depletions is similar, but this holds to a lesser extent for silicate. Depletions in March 2005 are 2-3 times larger than those in January 1993 for the same transect. Very low N:P and C:P depletion ratios seem to point to dominance of diatoms, in the central Weddell Sea more than in the margin. Estimates of annual net community productions are about 1.8 and 3.5 mol C m ¡2 year ¡1 for the interior Weddell Sea and a near-margin region, respectively. The region does not comply with the classical view of a marginal ice zone with high productivity. Net community production is similar to annual export production, implying that remineralization in the ensuing winter be minor.

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“…This is much higher than the mean annual flux values of 22 and 1.1 mg m y2 day y1 measured by sediment trap at 2700 and 900 m water depths in the Southern Ocean Ž . Honjo, 1996;Fisher et al, 1988 . Considering a water depth of 5300 m at our Southern Ocean station, the particle flux to the deep water and surface sediment has to be lower than that at NE Pacific.…”

Section: C Sedimentation Ratementioning

confidence: 99%

Radiocarbon and stable carbon isotope compositions of organic compound classes in sediments from the NE Pacific and Southern Oceans

Wang

Druffel

2001

Marine Chemistry

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AbstractŽ 14 .Ž 13 . Radiocarbon D C abundance and stable carbon isotope d C compositions were measured for total lipid, total Ž . Ž . hydrolyzable amino acids THAA , total carbohydrates TCHO , and acid-insoluble organic fractions separated from Ž . phytoplankton, zooplankton, and sediment cores collected from two abyssal sites, one in the northeast NE Pacific Ocean and one in the Southern Ocean. These results are compared with those obtained for a separate core from the NE Pacific and w Ž . In contrast, sediment from the Southern Ocean had much lower TOC and D 14 C values, which indicated that organic matter was extremely refractory. Sedimentation rates calculated from 14 C ages of TOC for both sites indicate that the differences in the organic composition and D 14 C signatures of organic matter in the sediments likely resulted from the differences in production and deposition of organic matter to the sediment, and the diagenetic stages of sedimentary organic matter in the two oceans. 14 Ž 13 . Unlike D C, stable carbon isotopic d C compositions of TOC in the sediments of the two oceans had similar values, which reflect not only the organic matter input from marine-derived sources but also the nature of degraded, predominately uncharacterized organic fraction in these sediments. The differences in d 13 C values among the compound classes in sediments at both sites can be attributed to the carbon isotopic signatures in original sources during photosynthesis and associated environmental factors. Preferential degradation of organic matter and heterotrophic effects may also play important roles for the observed d 13 C variations and these effects need to be further investigated. q 2001 Elsevier Science B.V. All rights reserved. -C. Wang, E.R.M. Druffelr Marine Chemistry 73 2001 65-81 66

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Seasonal variability of particle flux in the Weddell Sea and its relation to ice cover

Cited by 244 publications

References 14 publications

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

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

Whole season net community production in the Weddell Sea

Radiocarbon and stable carbon isotope compositions of organic compound classes in sediments from the NE Pacific and Southern Oceans

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