On the effects of circulation, sediment resuspension and biological  incorporation by diatoms in an ocean model of aluminium*

Hulten, Marco van; Sterl, Andreas; Middag, Rob; Baar, H. J. W. de; Gehlen, Marion; Dutay, Jean-Claude; Tagliabue, Alessandro

doi:10.5194/bg-11-3757-2014

Cited by 34 publications

(38 citation statements)

References 78 publications

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“…Thus it is now shown that the energetic bottom flow of the DSOW in the West Atlantic leads to elevated [Al], whereas the relatively stagnant bottom waters in the northeast basin have lower concentrations (Hall and Measures, 1998). The sediment resuspension source for Al is also confirmed in an ocean general circulation model that includes biogeochemistry and Al cycling (Van Hulten et al, 2014) and now also confirmed for the northwestern Atlantic basin by Measures et al (in press). …”

Section: North Atlantic Deep Watersupporting

confidence: 73%

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Dissolved aluminium in the ocean conveyor of the West Atlantic Ocean: Effects of the biological cycle, scavenging, sediment resuspension and hydrography

et al. 2015

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a b s t r a c tThe concentrations of dissolved aluminium (dissolved Al) were studied along the West Atlantic GEOTRACES GA02 transect from 64°N to 50°S. Concentrations ranged from~0.5 nmol kg −1 in the high latitude surface waters to~48 nmol kg −1 in surface waters around 25°N. Elevated surface water concentrations due to atmospheric dust loading have little influence on the deep water distribution. However, just below the thermocline, both Northern and Southern Hemisphere Subtropical Mode Waters are elevated in Al, most likely related to atmospheric dust deposition in the respective source regions. In the deep ocean, high concentrations of up to 35 nmol kg −1 were observed in North Atlantic Deep Water as a result of Al input via sediment resuspension. Comparatively low deep water concentrations were associated with water masses of Antarctic origin. During water mass advection, Al loss by scavenging overrules input via remineralisation and sediment resuspension at the basin wide scale. Nevertheless, sediment resuspension is more important than previously realised for the deep ocean Al distribution and even more intensive sampling is needed in bottom waters to constrain the spatial heterogeneity in the global deep ocean. This thus far longest (17,500 km) full depth ocean section shows that the distribution of Al can be explained by its input sources and the combination of association with particles and release from those particles at depth, the latter most likely when the particles remineralise. The association of Al with particles can be due to incorporation of Al into biogenic silica or scavenging of Al onto biogenic particles. The interaction between Al and biogenic particles can lead to the coupled cycling of Al and silicate that is observed in some ocean regions. However, in other regions this coupling is not observed due to (i) advective processes bringing in older water masses that are depleted in Al, (ii) unfavourable scavenging conditions in the water column, (iii) low surface concentrations of Al or (iv) additional Al sources, notably sediment resuspension.

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Section: North Atlantic Deep Watersupporting

confidence: 73%

“…3a and b). Elevated [Si] in bottom waters has been postulated to prevent release of Al from aluminosilicates in sediments (Mackin and Aller, 1986 (their equation (3) and related text); Van Hulten et al, 2014). Conversely, the low [Si] in the DSOW favours release and accumulation of [Al] in bottom water DSOW.…”

Section: North Atlantic Deep Watermentioning

confidence: 99%

Dissolved aluminium in the ocean conveyor of the West Atlantic Ocean: Effects of the biological cycle, scavenging, sediment resuspension and hydrography

et al. 2015

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“…1, has been employed for many other studies concerning trace metals, as well as large-scale ocean biogeochemistry (e.g. Gehlen et al, 2007;Arsouze et al, 2009;Dutay et al, 2009;Tagliabue et al, 2010;Van Hulten et al, 2014). The model simulates the biogeochemical sources and sinks of 24 prognostic tracers, including five limiting nutrients (Fe, PO 4 , Si(OH) 4 , NO 3 , and NH 4 ) Two phytoplankton groups (nanophytoplankton and diatoms) and two zooplankton size classes (microzooplankton and mesozooplankton) are represented in PISCES.…”

Section: The Biogeochemical Global Ocean Modelmentioning

confidence: 99%

Variable reactivity of particulate organic matter in a global ocean biogeochemical model

et al. 2017

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Abstract. The marine biological carbon pump is dominated by the vertical transfer of particulate organic carbon (POC) from the surface ocean to its interior. The efficiency of this transfer plays an important role in controlling the amount of atmospheric carbon that is sequestered in the ocean. Furthermore, the abundance and composition of POC is critical for the removal of numerous trace elements by scavenging, a number of which, such as iron, are essential for the growth of marine organisms, including phytoplankton. Observations and laboratory experiments have shown that POC is composed of numerous organic compounds that can have very different reactivities. However, this variable reactivity of POC has never been extensively considered, especially in modelling studies. Here, we introduced in the global ocean biogeochemical model NEMO-PISCES a description of the variable composition of POC based on the theoretical reactivity continuum model proposed by Boudreau and Ruddick (1991). Our model experiments show that accounting for a variable lability of POC increases POC concentrations in the ocean's interior by 1 to 2 orders of magnitude. This increase is mainly the consequence of a better preservation of small particles that sink slowly from the surface. Comparison with observations is significantly improved both in abundance and in size distribution. Furthermore, the amount of carbon that reaches the sediments is increased by more than a factor of 2, which is in better agreement with global estimates of the sediment oxygen demand. The impact on the major macronutrients (nitrate and phosphate) remains modest. However, iron (Fe) distribution is strongly altered, especially in the upper mesopelagic zone as a result of more intense scavenging: vertical gradients in Fe are milder in the upper ocean, which appears to be closer to observations. Thus, our study shows that the variable lability of POC can play a critical role in the marine biogeochemical cycles which advocates for more dedicated in situ and laboratory experiments.

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“…However, a recent comparison of thirteen Fe-incorporating GBMs found that 'all models struggle to reproduce many aspects of the observed spatial patterns' (Tagliabue et al, 2016). For other metals, such as Mn and Al, good agreement between observed and modeled values have been achieved in select parts of the global ocean (van Hulten et al, 2017(van Hulten et al, , 2014(van Hulten et al, , 2013. However, each GBM still struggles to replicate certain processes (e.g.…”

Section: Constraining the Particulate Export Of Trace Metalsmentioning

confidence: 99%

An investigation of basin-scale controls on upper ocean export and remineralization

Black¹

2018

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The biological carbon pump (BCP) helps to moderate atmospheric carbon dioxide levels by bringing carbon to the deep ocean, where it can be sequestered on timescales of centuries to millennia. Climate change is predicted to decrease the efficiency of the global BCP, however, the magnitude and timescale of this shift is largely uncertain and will likely impact some areas of the global ocean more significantly than others. Therefore, it is imperative that we (1) accurately quantify surface export and remineralization of particulate organic carbon (POC) via the BCP over large regions of the global ocean, (2) examine the factors controlling these POC fluxes and their variability, which includes the cycling of biologically-relevant trace metals, and (3) establish if and how the BCP is changing over time.This thesis focuses on addressing various aspects of these objectives using the 234 Th-238 U method across basin-scale GEOTRACES transects. First, the export and remineralization of POC were examined across large gradients in productivity, upwelling, community structure, and dissolved oxygen in the southeastern tropical Pacific Ocean. Although low oxygen zones are traditionally thought to have decreased POC flux attenuation relative to other regions of the global ocean and the low oxygen Pacific locations followed this pattern, regions that were functionally anoxic had enhanced attenuation in the upper 400 m. Second, trace metal export and remineralization were quantified across the Pacific transect. Because many trace metals are necessary for the metabolic functions of marine organisms and can co-limit marine productivity, the controls on the cycling of trace metals in the upper ocean were examined. Lastly, POC export was determined across two transects in the Western Arctic Ocean, where light and nutrient availability drive the biological pump. Upper ocean export estimates in the central basin did not reflect a substantial change in the biological pump compared to studies from the last three decades, however, an extensive maximum in 234 Th relative to 238 U deeper in the water column indicated that rapid vertical transport had occurred, which could suggest a more efficient biological pump in the Arctic Ocean.

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On the effects of circulation, sediment resuspension and biological incorporation by diatoms in an ocean model of aluminium*

Cited by 34 publications

References 78 publications

Dissolved aluminium in the ocean conveyor of the West Atlantic Ocean: Effects of the biological cycle, scavenging, sediment resuspension and hydrography

Dissolved aluminium in the ocean conveyor of the West Atlantic Ocean: Effects of the biological cycle, scavenging, sediment resuspension and hydrography

Variable reactivity of particulate organic matter in a global ocean biogeochemical model

An investigation of basin-scale controls on upper ocean export and remineralization

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