Silicon and zinc biogeochemical cycles coupled through the Southern Ocean

Vance, Derek; Little, Susan H.; Souza, Gregory F. de; Khatiwala, S.; Lohan, Maeve C.; Middag, Rob

doi:10.1038/ngeo2890

Cited by 113 publications

(166 citation statements)

References 41 publications

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“…In contrast, remineralization in diatom-rich regions such as the Southern Ocean and to a lesser extent the Arctic and sub-Arctic is expected to return both elements to the dissolved phase. This was previously observed in the formation regions of AAIW Zhao et al, 2014; see also Vance et al, 2017, their Figure 3a) and also evident from the positive intercept of the Zn-Si relationship in AAIW (not shown). Thus, the kink in the Zn-Si relationship at the transition between the highest latitude origin water and lower latitude origin water masses is predictable and reproduced in the eOMP model without the need to infer remineralization of Zn within the Atlantic.…”

Section: Zn-si Relationshipsupporting

confidence: 83%

“…However, the diatoms are not dominant everywhere and are most productive in coastal, upwelling and polar regions (Armbrust, 2009, and references therein) whereas in the oligotrophic Atlantic subtropical gyres, export production and diatom productivity are relatively low (Soppa et al, 2014). However, the slopes of regression are not only a function of the composition of the endmembers, determined by the preformed concentrations (surface concentrations at time of formation) and the remineralization ratio in the formation region as well as during advection to the Atlantic, but also influenced by mixing during advection in the Atlantic as previously suggested (Vance et al, 2017, their Figure 3b). In contrast, remineralization in diatom-rich regions such as the Southern Ocean and to a lesser extent the Arctic and sub-Arctic is expected to return both elements to the dissolved phase.…”

Section: Zn-si Relationshipmentioning

confidence: 58%

“…This suggests that Zn is predominantly present within the diatom siliceous frustules or that Zn is associated with a refractory organic phase, both of which would regenerate more slowly in the water column (i.e., at greater depth) compared to NO 3 and PO 4 (e.g., Lohan et al, 2002;Zhao et al, 2014). Alternatively, the coupling of Zn and Si might be coupled via strong depletion of both nutrients in the Southern Ocean (e.g., Ellwood, 2008;Saito et al, 2010;Sunda & Huntsman, 2000;Vance et al, 2017;Wyatt et al, 2014) or a combination of both scavenging and the strong depletion in the Southern Ocean (Weber et al, 2018). This would imply Zn should regenerate in a similar way as other nutrients and nutrient metals and have a distribution that more closely resembles NO 3 and PO 4 .…”

Section: Introductionmentioning

confidence: 99%

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The Relationships Between Dissolved Zinc and Major Nutrients Phosphate and Silicate Along the GEOTRACES GA02 Transect in the West Atlantic Ocean

Middag

Baar

Bruland

2019

Global Biogeochemical Cycles

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Dissolved zinc (Zn) has a nutrient‐type distribution in the ocean that more closely resembles the distribution of silicate (Si) than phosphate (PO4). However, Zn is a trace‐nutrient and mostly present in the organic fraction of phytoplankton rather than the siliceous frustule. It has been suggested the coupling of Zn and Si is caused by the strong depletion of nutrients in the Southern Ocean, possibly combined with scavenging of Zn. Here we assess the distribution of Zn and nutrients along the conduit of southward traveling waters of northern origin and northward traveling waters of Antarctic origin to unravel the influence of various water masses and local biogeochemical processes in the Atlantic Ocean. The distribution of Zn and Si is governed by mixing such that influence of remineralization is barely distinguishable, whereas the distribution of PO4 is influenced by both processes. The subsurface water masses that supply nutrients to the surface ocean are depleted in Zn. Indeed, the Southern Ocean water masses play a driving role, but remarkably, also subsurface water masses from northern high‐latitude origin are depleted in Zn. Both northern and southern high‐latitude waters have a relatively high Zn:PO4 uptake and remineralization ratio, implying it is Zn availability and not only chronic iron limitation that leads to increased Zn uptake in the high‐latitude regions. The limited supply of Zn to the surface Atlantic Ocean can explain the lack of an Atlantic Zn remineralization signal and indicates Zn might play a role in phytoplankton community composition and productivity.

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Section: Zn-si Relationshipsupporting

confidence: 83%

Section: Zn-si Relationshipmentioning

confidence: 58%

Section: Introductionmentioning

confidence: 99%

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The Relationships Between Dissolved Zinc and Major Nutrients Phosphate and Silicate Along the GEOTRACES GA02 Transect in the West Atlantic Ocean

Middag

Baar

Bruland

2019

Global Biogeochemical Cycles

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“…For Zn (e.g. Vance et al 2017) this dominance is especially important because the diatoms that strip this water of silicon take up 10 times more Zn relative to phosphorous than other oceanic phytoplankton. As a result, Zn concentrations drop by a factor of 40 as water is moved away from the upwelling zone in the surface flow.…”

Section: Introductionmentioning

confidence: 99%

The oceanic cycles of the transition metals and their isotopes

et al. 2017

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The stable isotope systems of the transition metals potentially provide constraints on the current and past operation of the biological pump, and on the state of ocean redox in Earth history. Here we focus on two exemplar metals, nickel (Ni) and zinc (Zn). The oceanic dissolved pool of both elements is isotopically heavier than the known inputs, implying an output with light isotope compositions. The modern oceanic cycle of both these elements is dominated by biological uptake into photosynthesised organic matter and output to sediment. It is increasingly clear, however, that such uptake is associated with only very minor isotope fractionation. We suggest that the isotopic balance is instead closed by the sequestration of light isotopes to sulphide in anoxic and organic-rich sediments, so that it is ocean chemistry that controls these isotope systems, and suggesting a different but equally interesting array of questions in Earth history that can be addressed with these systems.

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“…The TMM has been applied to a wide range of problems, including simulating anthropogenic carbon uptake and radiocarbon by the ocean (Graven et al, 2012), simulating noble gases to improve the parameterization of air-sea gas transfer (Nicholson et al, 2011;Liang et al, 2013) and investigate ocean ventilation (Nicholson et al, 2016), studying ocean proxy (Siberlin and Wunsch, 2011) and radiocarbon (Koeve et al, 2015) timescales, investigating the mechanisms controlling nutrient ratios (Weber and Deutsch, 2010), modeling the cycling of particle reactive geochemical tracers Siddall et al, 2008;Vance et al, 2017), estimating respiration in the ocean from oxygen utilization rates (Duteil et al, 2013;Koeve and Kähler, 2016), demonstrating the utility of atmospheric potential oxygen measurements to constrain ocean heat transport , modeling the ocean's CaCO 3 (Koeve et al, 2014) and nitrogen (Kriest and Oschlies, 2015) cycles; studying the impact of the Southern Ocean on global ocean oxygen (Keller et al, 2016), estimating the flux of organic matter (Wilson et al, 2015), and biogeochemical parameter sensitivity (Khatiwala, 2007;Kriest et al, 2010Kriest et al, , 2012 and optimization (Priess et al, 2013b, a;Kriest et al, 2017).…”

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confidence: 99%

Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers

et al. 2017

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Abstract. Conventional integration of Earth system and ocean models can accrue considerable computational expenses, particularly for marine biogeochemical applications. "Offline" numerical schemes in which only the biogeochemical tracers are time stepped and transported using a precomputed circulation field can substantially reduce the burden and are thus an attractive alternative. One such scheme is the "transport matrix method" (TMM), which represents tracer transport as a sequence of sparse matrix-vector products that can be performed efficiently on distributed-memory computers. While the TMM has been used for a variety of geochemical and biogeochemical studies, to date the resulting solutions have not been comprehensively assessed against their "online" counterparts. Here, we present a detailed comparison of the two. It is based on simulations of the state-of-the-art biogeochemical sub-model embedded within the widely used coarse-resolution University of Victoria Earth System Climate Model (UVic ESCM). The default, non-linear advection scheme was first replaced with a linear, third-order upwind-biased advection scheme to satisfy the linearity requirement of the TMM. Transport matrices were extracted from an equilibrium run of the physical model and subsequently used to integrate the biogeochemical model offline to equilibrium. The identical biogeochemical model was also run online. Our simulations show that offline integration introduces some bias to biogeochemical quantities through the omission of the polar filtering used in UVic ESCM and in the offline application of time-dependent forcing fields, with high latitudes showing the largest differences with respect to the online model. Differences in other regions and in the seasonality of nutrients and phytoplankton distributions are found to be relatively minor, giving confidence that the TMM is a reliable tool for offline integration of complex biogeochemical models. Moreover, while UVic ESCM is a serial code, the TMM can be run on a parallel machine with no change to the underlying biogeochemical code, thus providing orders of magnitude speed-up over the online model.

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Silicon and zinc biogeochemical cycles coupled through the Southern Ocean

Cited by 113 publications

References 41 publications

The Relationships Between Dissolved Zinc and Major Nutrients Phosphate and Silicate Along the GEOTRACES GA02 Transect in the West Atlantic Ocean

The Relationships Between Dissolved Zinc and Major Nutrients Phosphate and Silicate Along the GEOTRACES GA02 Transect in the West Atlantic Ocean

The oceanic cycles of the transition metals and their isotopes

Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers

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