Deep water particle flux in the Canary Island region: seasonal trends in relation to long-term satellite derived pigment data and lateral sources

Neuer, Susanne; Ratmeyer, Volker; Davenport, Robert; Fischer, Gerhard; Wefer, Gerold

doi:10.1016/s0967-0637(97)00034-4

Cited by 106 publications

(76 citation statements)

References 28 publications

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“…Opal contents in the sediments are low, as samples with significantly higher biogenic silica concentration than average shale would plot closer to the SiO 2 corner. This assumption is supported by the investigations of Neuer et al (1997) who observed on average very low opal contents in this region.…”

Section: Map Generationsupporting

confidence: 67%

Geochemical distribution patterns as indicators for productivity and terrigenous input off NW Africa

Plewa

Meggers

Kuhlmann

et al. 2012

Deep Sea Research Part I: Oceanographic Research Papers

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a b s t r a c tOne hundred and twenty-eight surface-sediment samples collected off North-West Africa were studied geochemically to detect the expressions of different meridional climate regimes and zonal productivity gradients in the surface sediments. This geochemical multi-tracer approach, coupled with additional information on the bulk carbonate and TOC contents makes it possible to characterise the sedimentological regime in detail. Typical terrigenous elements like Al, K and Fe mirror the importance of the humid (fluvial) influence in the north of the study area and the dominance of aeolian input in the south. Furthermore, the distributions of Ti and Fe in the surface sediments serve as tracers for the supply of eolian volcanic material from the Canary Islands. The spatial variability of the TOC contents in the surface sediments closely follows the ocean surface productivity patterns, whereas the CaCO 3 contents are mainly controlled by dilution with terrigenous matter. The potential productivity proxy Ba is not a reliable tracer for productivity in this region, since it is mainly supplied by terrigenous input (coupled with aluminosilicates).

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Section: Map Generationsupporting

confidence: 67%

Geochemical distribution patterns as indicators for productivity and terrigenous input off NW Africa

Plewa

Meggers

Kuhlmann

et al. 2012

Deep Sea Research Part I: Oceanographic Research Papers

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“…6). This might be caused by lateral advection of organic rich particles (e.g., from flagellates) to the sampling site from the outer Cape Ghir filament located far to the east of the study site (Neuer et al, 1997). The lower opal fluxes collected by the trap compared to the model are difficult to explain, but may be attributed to either dissolution of opal in the cups (due to very low contents) or an undersampling of smaller diatoms followed by disintegration of diatom-containing fecal pellets at greater depths, or both.…”

Section: Discussionmentioning

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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“…They would also substantially decrease the estimated "lateral" or "advective" fluxes that are assumed where an increase in flux with depth is measured (e.g. Neuer et al, 1997;Antia et al, 1999) and narrow the observed discrepancy between vertical POC fluxes and sediment community carbon demand (Lampitt et al, 1995;Smith et al, 2001). Central to the need or even ability to correct for solubilization, trap collection bias or other artifacts is our confidence in the level of accuracy with which we can measure sinking fluxes and the level of accuracy that is needed for the process to be investigated.…”

Section: "Correcting" For Particle Solubilizationmentioning

confidence: 99%

Solubilization of particles in sediment traps: revising the stoichiometry of mixed layer export

Antia¹

2005

Biogeosciences

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Abstract. Sinking particles, once caught in sediment trap jars, release dissolved elements into the surrounding medium through leaching from their pore fluids, chemical dissolution and the activity of free exoenzymes. This results in an increase in dissolved elements in the trap jar supernatant. Elemental fluxes as traditionally measured by sediment traps underestimate total export when this particle-associated dissolved flux is not considered. The errors introduced are variable and alter both the absolute levels of flux as well as the stoichiometry of export. These errors have been quantified and corrections applied for samples from sediment traps in the North Atlantic based on measurements of excess dissolved carbon, nitrogen, phosphorus, silica and calcium in the supernatant of the collection cups. At the base of the winter mixed layer, on average 90±6% of phosphorus fluxes are found as excess phosphate whereas for carbon and nitrogen dissolved concentrations account for 30 (±8)% and 47(±11)% of total fluxes respectively. Excess dissolved silica is on average 61 (±17)% of total biogenic silica flux. Little (<10%) of calcium is solubilized. The proportion of dissolved to total flux decreases with trap deployment depth. Calculations of the C:N:P ratios for particles only are well above the Redfield ratios of 106:16:1 (Redfield et al., 1963), although the mid-water dissolved N:P and N:Si values as well as the C:N:P ratios of remineralisation along isopycnals conform to the Redfield ratios at this site. Accounting for dissolved fluxes of all these elements brings the stoichiometry of export in agreement with the Redfield Ratio and with other geochemical estimates of winter mixed layer export. A factor of 3 to 4 higher ratios of organic: inorganic carbon export also implies that the net atmospheric CO 2 sequestration by the biological pump is about 50% higher at this site when the dissolved elemental fluxes are considered. Solubilization is thus a process that should be accounted for in protocols used to measure vertical fluxes with sediment traps.

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Deep water particle flux in the Canary Island region: seasonal trends in relation to long-term satellite derived pigment data and lateral sources

Cited by 106 publications

References 28 publications

Geochemical distribution patterns as indicators for productivity and terrigenous input off NW Africa

Geochemical distribution patterns as indicators for productivity and terrigenous input off NW Africa

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

Solubilization of particles in sediment traps: revising the stoichiometry of mixed layer export

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