The relative contribution of fast and slow sinking particles to ocean carbon export

Riley, J.P.; Sanders, Richard; Marsay, Chris M.; Moigne, Frédéric A.C. Le; Achterberg, Eric P.; Poulton, Alex J.

doi:10.1029/2011gb004085

Cited by 182 publications

(273 citation statements)

References 63 publications

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“…Satellite chlorophyll imagery and horizontal velocities (obtained using a 150-kHz Vessel-Mounted Acoustic Doppler Current Profiler) confirmed that all of the traps were advected along the edge of an anticyclonic eddy for 50 km before surfacing within 3.5 km of each other. Measured POC flux at 50 m (84±8 mg C m -2 d -1 ) was close to independently derived estimates using 234 Th budgets and studies of collected marine snow particles (99±41 and 146±26 mg C m -2 d -1 , respectively) 13 . Flux attenuation with depth followed the Martin curve (F = F 100 (z/100) b ) 9 with b = -0.70 (p<0.01, R 2 =0.95, n=5) and was consistent with observations in the Pacific Ocean (b: -0.50 to -1.38; Fig.…”

supporting

confidence: 80%

Reconciliation of the carbon budget in the ocean’s twilight zone

Giering

Sanders

Lampitt

et al. 2014

Nature

308

347

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The global carbon cycle is affected by biological processes in the oceans, which export carbon from surface waters in form of organic matter and store it at depth; a process called the 'biological carbon pump'. Most of the exported organic carbon is processed by the water column biota, which ultimately converts it into CO2 via respiration (remineralization). Variations in the resulting decrease in organic flux with depth 9 can, according to models, lead to changes in atmospheric CO 2 of up to 200 ppm 3 , indicating a strong coupling between biological activity in the ocean interior and oceanic storage of CO 2 .A key constraint in the analysis of carbon fluxes in the twilight zone is that, at steady state, the attenuation of particulate organic carbon (POC) flux with depth should be balanced by community metabolism. Published estimates of POC flux attenuation with depth are, however, up to 2 orders of magnitude lower than corresponding estimates of heterotrophic metabolism [4][5][6][7] . This discrepancy indicates that either estimates of POC flux and/or community metabolism are unreliable, or that additional, unaccounted for, sources of organic carbon to the twilight zone exist 8 .We compiled a comprehensive carbon budget of the twilight zone based on an based on the ratio between DOC concentrations and apparent oxygen utilization 15 , and on DOC gradients coupled to turbulent diffusivity measured from previous work at the study site 16 (Methods; Extended Data Fig. 2). DOC was estimated to supply 17% of total export in agreement with previous estimates of 9-20% across the North Atlantic basin 17 . Organic matter input via lateral advection was assumed to be negligible based on analyses of back-trajectories (derived from satellite-derived near-surface velocities over 3 months) of the water masses arriving at the PAP site during the study period, which suggested that the water had not passed over the continental slope (Extended Data Fig. 1b). The final source of DOC, excretion at depth by active flux, was estimated using net samples of zooplankton biomass and allometric equations 6,18 , giving a supply of 3 mg C m -2 d -1 . Defecation and mortality at depth present further sources of organic carbon to the twilight zone, but these were excluded from the budget due to large uncertainties associated with their estimation. Finally, chemolithoautotrophy has been suggested to be a significant source of organic matter in the deep ocean 19 , but without strong evidence that this poorly understood process could provide a major contribution at our study site, we chose to exclude it from our carbon budget.The remineralization of organic carbon by zooplankton and prokaryotes was estimated from zooplankton biomass and prokaryotic activity. It is crucial to note that in a steady state system, such as we assume this to be, organic carbon is lost from the system only by export or by remineralization. We focus entirely on community respiration as a measure of remineralization, a fundamental advance over previous methods to derive...

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supporting

confidence: 80%

Reconciliation of the carbon budget in the ocean’s twilight zone

Giering

Sanders

Lampitt

et al. 2014

Nature

308

347

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“…The probable composition of sinking aggregates (the high content of lithogenic material and the low amount of relatively buoyant OM), as well as their sinking velocity (∼ 24-86 m d −1 ; Bressac et al, 2012) suggest low specific carbon remineralization (Riley et al, 2012). Furthermore, the inherent sporadic character of the lithogenic carbon pump may play a fundamental role in carbon sequestration (Ragueneau et al, 2006) since episodic events may lead to the rapid sinking of particles that will not be fully exploited by the deep sea bacterial community (Hansell and Ducklow, 2003;Nagata et al, 2000Nagata et al, , 2010.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, it has been demonstrated that minerals could increase the velocity at which aggregates sink (e.g., De La Rocha and Passow, 2007;De La Rocha et al, 2008;Thomalla et al, 2008;Engel et al, 2009b; and drive large POC flux events (e.g., Thunell et al, 2007;Lee et al, 2009;Sanders et al, 2010;Ternon et al, 2010). Such fast-sinking POC, negligible within the euphotic zone, is sufficient to explain deep-ocean POC fluxes (Honda and Watanabe, 2010;Riley et al, 2012); this emphasizes the importance of the mode by which carbon is transferred downward when considering carbon flux parameterization.…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

Quantification of the lithogenic carbon pump following a simulated dust-deposition event in large mesocosms

et al. 2014

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Abstract. Lithogenic particles, such as desert dust, have been postulated to influence particulate organic carbon (POC) export to the deep ocean by acting as mineral ballasts. However, an accurate understanding and quantification of the POC-dust association that occurs within the upper ocean is required in order to refine the "ballast hypothesis". In the framework of the DUNE (a DUst experiment in a lowNutrient, low-chlorophyll Ecosystem) project, two artificial seedings were performed seven days apart within large mesocosms. A suite of optical and biogeochemical measurements were used to quantify surface POC export following simulated dust events within a low-nutrient, low-chlorophyll ecosystem. The two successive seedings led to a 2.3-6.7-fold higher POC flux than the POC flux observed in controlled mesocosms. A simple linear regression analysis revealed that the lithogenic fluxes explained more than 85 % of the variance in POC fluxes. On the scale of a dust-deposition event, we estimated that 42-50 % of POC fluxes were strictly associated with lithogenic particles (through aggregation and most probably sorption processes). Lithogenic ballasting also likely impacted the remaining POC fraction which resulted from the fertilization effect. The observations support the "ballast hypothesis" and provide a quantitative estimation of the surface POC export abiotically triggered by dust deposition. In this work, we demonstrate that the strength of such a "lithogenic carbon pump" depends on the biogeochemical conditions of the water column at the time of deposition. Based on these observations, we suggest that this lithogenic carbon pump could represent a major component of the biological pump in oceanic areas subjected to intense atmospheric forcing.

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“…The slope of the particle-size spectrum is highly variable (Guidi et al, 2009). Measurements have shown that the majority of the flux is composed of slow (< 10 m day −1 ) and fast (> 350 m day −1 ) sinking particles (Riley et al, 2012;Alonso-Gonzalez et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

A stochastic, Lagrangian model of sinking biogenic aggregates in the ocean (SLAMS 1.0): model formulation, validation and sensitivity

Jokulsdottir

Archer

2016

Geosci. Model Dev.

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Abstract. We present a new mechanistic model, stochastic, Lagrangian aggregate model of sinking particles (SLAMS) for the biological pump in the ocean, which tracks the evolution of individual particles as they aggregate, disaggregate, sink, and are altered by chemical and biological processes. SLAMS considers the impacts of ballasting by mineral phases, binding of aggregates by transparent exopolymer particles (TEP), zooplankton grazing and the fractal geometry (porosity) of the aggregates. Parameterizations for age-dependent organic carbon (orgC) degradation kinetics, and disaggregation driven by zooplankton grazing and TEP degradation, are motivated by observed particle fluxes and size spectra throughout the water column. The model is able to explain observed variations in orgC export efficiency and rain ratio from the euphotic zone and to the sea floor as driven by sea surface temperature and the primary production rate and seasonality of primary production. The model provides a new mechanistic framework with which to predict future changes on the flux attenuation of orgC in response to climate change forcing.

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The relative contribution of fast and slow sinking particles to ocean carbon export

Cited by 182 publications

References 63 publications

Reconciliation of the carbon budget in the ocean’s twilight zone

Reconciliation of the carbon budget in the ocean’s twilight zone

Quantification of the lithogenic carbon pump following a simulated dust-deposition event in large mesocosms

A stochastic, Lagrangian model of sinking biogenic aggregates in the ocean (SLAMS 1.0): model formulation, validation and sensitivity

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