Chemical Tracers of Particle Transport

Anderson, Robert F.

doi:10.1016/b978-0-08-095975-7.00609-4

Cited by 8 publications

(5 citation statements)

References 146 publications

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“…Only some FeMIP models attempt to account for this process (Table ), yet given the apparent importance of colloidal Fe within the DFe fraction [ Boye et al , ; Fitzsimmons and Boyle , ; Wu et al , ], colloidal pumping losses might be as large as those from the scavenging of free Fe. Some progress may be made by exploiting the legacy from the field of Thorium (Th) cycling, for which a number of different theories have been developed to describe its scavenging, including colloidal components [ Anderson , ; Burd et al , ; Lam and Marchal , ; Marchal and Lam , ; Savoye et al , ]. With an expanding database of paired Fe and Th observations, including the particulate phase, as part of GEOTRACES [ Mawji et al , ] it may be possible to refine this crucial component of the Fe cycle in the coming years.…”

Section: Discussionmentioning

confidence: 99%

How well do global ocean biogeochemistry models simulate dissolved iron distributions?

Tagliabue

Aumont

Death

et al. 2016

Global Biogeochemical Cycles

274

387

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Numerical models of ocean biogeochemistry are relied upon to make projections about the impact of climate change on marine resources and test hypotheses regarding the drivers of past changes in climate and ecosystems. In large areas of the ocean, iron availability regulates the functioning of marine ecosystems and hence the ocean carbon cycle. Accordingly, our ability to quantify the drivers and impacts of fluctuations in ocean ecosystems and carbon cycling in space and time relies on first achieving an appropriate representation of the modern marine iron cycle in models. When the iron distributions from 13 global ocean biogeochemistry models are compared against the latest oceanic sections from the GEOTRACES program, we find that all models struggle to reproduce many aspects of the observed spatial patterns. Models that reflect the emerging evidence for multiple iron sources or subtleties of its internal cycling perform much better in capturing observed features than their simpler contemporaries, particularly in the ocean interior. We show that the substantial uncertainty in the input fluxes of iron results in a very wide range of residence times across models, which has implications for the response of ecosystems and global carbon cycling to perturbations. Given this large uncertainty, iron fertilization experiments based on any single current generation model should be interpreted with caution. Improvements to how such models represent iron scavenging and also biological cycling are needed to raise confidence in their projections of global biogeochemical change in the ocean.

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Section: Discussionmentioning

confidence: 99%

How well do global ocean biogeochemistry models simulate dissolved iron distributions?

Tagliabue

Aumont

Death

et al. 2016

Global Biogeochemical Cycles

274

387

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“…Removal of trace elements by particle scavenging has a first-order control on their concentrations in the ocean (Anderson, 2014). This is true for mercury (Hg) as well: particle scavenging represents the ultimate sink for Hg from the ocean over centuries, and it is eventually back to the deep mineral reservoir on the timescales of glacial cycle (e.g., Amos et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Particle Composition and Concentration on the Partitioning Coefficient for Mercury in Three Ocean Basins

Cui

Lamborg

Hammerschmidt

et al. 2021

Front. Environ. Chem.

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The downward flux of sinking particles is a prominent Hg removal and redistribution process in the ocean; however, it is not well-constrained. Using data from three U.S. GEOTRACES cruises including the Pacific, Atlantic, and Arctic Oceans, we examined the mercury partitioning coefficient, Kd, in the water column. The data suggest that the Kd varies widely over three ocean basins. We also investigated the effect of particle concentration and composition on Kd by comparing the concentration of small-sized (1–51 μm) suspended particulate mass (SPM) as well as its compositional fractions in six different phases to the partitioning coefficient. We observed an inverse relationship between Kd and suspended particulate mass, as has been observed for other metals and known as the “particle concentration effect,” that explains much of the variation in Kd. Particulate organic matter (POM) and calcium carbonate (CaCO3) dominated the Hg partitioning in all three ocean basins while Fe and Mn could make a difference in some places where their concentrations are elevated, such as in hydrothermal plumes. Finally, our estimated Hg residence time has a strong negative correlation with average log bulk Kd, indicating that Kd has significant effect on Hg residence time.

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“…The fact that particles with a wide variety of sizes are present in the ocean raises a question: Why does particle size range around 35–75 µm contribute mainly to the lateral transport of Fe? Although we have not distinguished between adsorption and aggregation (desorption and disaggregation) in the model, these are fundamentally different processes: Adsorption (desorption) represents the association (dissociation) of particle‐reactive elements with binding sites of particles, including colloids, whereas aggregation (disaggregation) represents association (dissociation) among the particles themselves (Anderson, 2013; Honeyman & Santschi, 1991). We speculate that aggregation and disaggregation processes concentrate Fe‐rich particles in that size fraction.…”

Section: Resultsmentioning

confidence: 99%

Slowly Sinking Particles Underlie Dissolved Iron Transport Across the Pacific Ocean

Misumi

Nishioka

Obata

et al. 2021

Global Biogeochemical Cycles

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Chemical Tracers of Particle Transport

Cited by 8 publications

References 146 publications

How well do global ocean biogeochemistry models simulate dissolved iron distributions?

How well do global ocean biogeochemistry models simulate dissolved iron distributions?

The Effect of Particle Composition and Concentration on the Partitioning Coefficient for Mercury in Three Ocean Basins

Slowly Sinking Particles Underlie Dissolved Iron Transport Across the Pacific Ocean

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