High resolution profiles of vertical particulate organic matter export off Cape Blanc, Mauritania: Degradation processes and ballasting effects

Iversen, Morten Hvitfeldt; Nowald, Nicolas; Ploug, Helle; Jackson, George A.; Fischer, Gerhard

doi:10.1016/j.dsr.2010.03.007

Cited by 169 publications

(189 citation statements)

References 69 publications

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“…These findings are mostly in 1-10 to 70 0 0 anammox denitrification (in presence of H 2 S) 0 0 * Calculated based on the Redfield ratio of C : N = 106 : 16 using the primary production and N 2 fixation rates given in this table in consistency with the % contribution given in Duce et al (2008). a Kalvelage et al (2013); b Dale et al (2015); c Behrenfeld and Falkowski (1997); d Longhurst et al (1995); e Iversen et al (2010); f Dekaezemacker et al (2013) and Löscher et al (2014); g Voss et al (2004). accordance with other studies from this area (Bonnet et al, 2013;Fernandez et al, 2011;Turk-Kubo et al, 2014). The excess P generated within the OMZ seemed to be consumed by non-Redfield processes, i.e., primary production by large phytoplankton found in shelf surface waters, instead of stimulating surface N 2 fixation.…”

Section: Primary Production In the Etsp And Etnasupporting

confidence: 62%

“…This difference may be due to intensified N loss mirrored by a strongly positive δ 15 N-nitrate signal (Ryabenko et al, 2012) in the more O 2 -depleted water column and sediments of the ETSP. On the other hand, enhanced P release from the sediments at decreasing O 2 (Ingall and Jahnke, 1994), or a difference between N and P remineralization from organic material (Jilbert et al, 2011), may impact decreased N : P ratios. A stronger N deficit in the water column may influence primary production in different ways: it may stimulate N 2 fixation in order to replenish the N deficit, or it may stimulate non-Redfield primary production.…”

Section: Primary Production In the Etsp And Etnamentioning

confidence: 99%

“…Only a few studies have addressed upper ocean export fluxes and mesopelagic flux attenuation in tropical OMZs (Martin et al (1987), Devol and Hartnett (2001) and Van Mooy et al (2002) for the eastern tropical Pacific by means of surface tethered sediment traps; Buesseler et al (1998) for the Arabian Sea by means of 234 Th;and Iversen et al (2010) at the northern edge of the ETNA OMZ by means of particle camera profiling). In the eastern tropical North Pacific (ETNP) (Martin et al, 1987;Van Mooy et al, 2002;Devol and Hartnett, 2001) and the ETSP (Martin et al 1987;Dale et al, 2015) mesopelagic POC fluxes were less attenuated with depth (Martin curve exponent "b" of 0.32-0.81) compared with the widely used "open-ocean composite" of b = 0.86 (Martin et al, 1987).…”

Section: Sinking Of Particlesmentioning

confidence: 99%

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Water column biogeochemistry of oxygen minimum zones in the eastern tropical North Atlantic and eastern tropical South Pacific oceans

et al. 2016

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Abstract. Recent modeling results suggest that oceanic oxygen levels will decrease significantly over the next decades to centuries in response to climate change and altered ocean circulation. Hence, the future ocean may experience major shifts in nutrient cycling triggered by the expansion and intensification of tropical oxygen minimum zones (OMZs), which are connected to the most productive upwelling systems in the ocean. There are numerous feedbacks among oxygen concentrations, nutrient cycling and biological productivity; however, existing knowledge is insufficient to understand physical, chemical and biological interactions in order to adequately assess past and potential future changes.In the following, we summarize one decade of research performed in the framework of the Collaborative Research Center 754 (SFB754) focusing on climate-biogeochemistry interactions in tropical OMZs. We investigated the influence of low environmental oxygen conditions on biogeochemical cycles, organic matter formation and remineralization, greenhouse gas production and the ecology in OMZ regions of the eastern tropical South Pacific compared to the weaker OMZ of the eastern tropical North Atlantic. Based on our findings, a coupling of primary production and organic matter export via the nitrogen cycle is proposed, which may, however, be impacted by several additional factors, e.g., micronutrients, particles acting as microniches, vertical and horizontal transport of organic material and the role of zooplankton and viruses therein.

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Section: Primary Production In the Etsp And Etnasupporting

confidence: 62%

Section: Primary Production In the Etsp And Etnamentioning

confidence: 99%

Section: Sinking Of Particlesmentioning

confidence: 99%

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Water column biogeochemistry of oxygen minimum zones in the eastern tropical North Atlantic and eastern tropical South Pacific oceans

et al. 2016

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“…These instruments have been used to study biogeochemical cycles combining particle information from camera systems and sediment trap measurements of particle flux in order to better estimate particle sinking rate, a characteristic influencing particle export (Asper, 1987;Asper et al, 1992;Diercks and Asper, 1997;Gardner and Walsh, 1990;Guidi et al, 2008;Iversen et al, 2010;Jackson et al, 1997;Jouandet et al, 2011;McDonnell and Buesseler, 2010;Peterson et al, 2005;Walsh and Hunter, 1992). Systems such as the In Situ Ichthyoplankton Imaging System ISIIS (Cowen and Guigand, 2008), the Zooplankton Visualization and Imaging System ZOOVIS (Benfield et al, 2007) and the Shadowed Image Particle Profiler and Evaluation Recorder (SIP-PER, Samson et al, 2001) allow counting and sizing of large zooplankton from images.…”

Section: Optical Imaging Of Particle Abundance and Size Distributionmentioning

confidence: 99%

Optical techniques for remote and in-situ characterization of particles pertinent to GEOTRACES

Boss

Guidi

Richardson

et al. 2015

Progress in Oceanography

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a b s t r a c tField and laboratory characterization of marine particles is laborious and expensive. Proxies of particle properties have been developed that allow researchers to obtain high frequency distributions of such properties in space or time. We focus on optical techniques used to characterize marine particles in-situ, with a focus on GEOTRACES-relevant properties, such as bulk properties including particle mass, crosssectional area, particle size distribution, particle shape information, and also single particle optical properties, such as individual particle type and size. We also address the use of optical properties of particles to infer particulate organic or inorganic carbon. In addition to optical sensors we review advances in imaging technology and its use to study marine particles in situ. This review addresses commercially available technology and techniques that can be used as a proxy for particle properties and the associated uncertainties with particular focus to open ocean environments, the focus of GEOTRACES.

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“…100-300 m below the euphotic zone depth, our understanding of the processes affecting sinking particles throughout this layer is still poor (Buesseler and Boyd, 2009). The vertical flux of organic matter throughout the water column is dominated by large particles such as marine snow and faecal pellets (Ebersbach et al, 2011;Fowler and Knauer, 1986;Laurenceau-Cornec et al, 2015) that can be attenuated to a large extent by zooplankton and microbial degradation (Giering et al, 2014;Iversen et al, 2010;Kiørbe, 2000;Smith et al, 1992). However, packaging of slowly sinking phytoplankton cells into large faecal pellets may play a key role in increasing the export and transfer efficiencies in the Southern Ocean (Cavan et al, 2015;Le Moigne et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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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High resolution profiles of vertical particulate organic matter export off Cape Blanc, Mauritania: Degradation processes and ballasting effects

Cited by 169 publications

References 69 publications

Water column biogeochemistry of oxygen minimum zones in the eastern tropical North Atlantic and eastern tropical South Pacific oceans

Water column biogeochemistry of oxygen minimum zones in the eastern tropical North Atlantic and eastern tropical South Pacific oceans

Optical techniques for remote and in-situ characterization of particles pertinent to GEOTRACES

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

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