Low colloidal associations of aluminium and titanium in surface waters of the tropical Atlantic

Dammshäuser, Anna; Croot, Peter

doi:10.1016/j.gca.2012.07.032

Cited by 26 publications

(18 citation statements)

References 85 publications

(150 reference statements)

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“…Low contributions of colloids to the dissolved phase have been observed for Mn and Cr in Louisiana Shelf waters (excluding low-salinity samples) [Joung and Shiller, 2016]. Other lithogenic metals (Ti and Al) were also found to have low (<3%) colloidal contributions to the dissolved phase in oceanic waters of the tropical Atlantic [Dammshäuser and Croot, 2012].…”

Section: Atlantic-pacific Contrast In Fe and Other Lithogenic Metalsmentioning

confidence: 99%

Thorium distributions in high‐ and low‐dust regions and the significance for iron supply

Hayes

Rosen

McGee

et al. 2017

Global Biogeochemical Cycles

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Thorium and uranium isotopes (232Th, 230Th, 238U, and 234U) were investigated to refine their use for estimating mineral dust deposition and Fe delivery to the ocean. U concentrations and isotope ratios were consistent with conservative behavior and can safely be described using published U‐salinity relationships and global average seawater isotopic composition. Near Barbados, waters affected by the Amazon outflow contained elevated 232Th. This signals one region where the thorium‐dust method is inaccurate because of a confounding continental input. Dissolved 232Th fluxes in this region suggest that Amazonian Fe supply to the adjacent open ocean is much larger than local atmospheric deposition. The colloidal content of dissolved Th south of Bermuda was found to be quite small (2–6%), similar to that found north of Hawaii, despite the order of magnitude higher dust deposition in the Atlantic. This finding supports the assumption that dissolved 232Th and 230Th are scavenged at the same rate despite their different sources and also sheds light on the increase of dissolved 232Th fluxes with integrated depth. Outside the region influenced by Amazon River waters, dissolved 232Th fluxes are compared with Bermudan aerosol Fe deposition to estimate that fractional Th solubility is around 20% in this region. Finally, new dissolved and soluble Fe, Mn, and Cr data from the subtropical North Pacific support the idea that Fe concentrations in the remote ocean are highly buffered, whereas 232Th has a larger dynamic range between high‐ and low‐dust regions.

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Section: Atlantic-pacific Contrast In Fe and Other Lithogenic Metalsmentioning

confidence: 99%

Thorium distributions in high‐ and low‐dust regions and the significance for iron supply

Hayes

Rosen

McGee

et al. 2017

Global Biogeochemical Cycles

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“…12c, lower panels), allows creation of a sub-euphotic minimum in SSF particulates (Dammshauser and Croot, 2012) and the upper watercolumn LSF dominance that we observe in the actual water column (Fig. 11).…”

Section: Lithogenic Particle Cycling 1-d Model: Resultsmentioning

confidence: 69%

The biogeochemistry of marine particulate trace metals

Ohnemus¹

2014

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Marine particles include all living and non-living solid components of seawater, representing an extremely dynamic and chemically diverse mixture of phases. The distributions of these phases are poorly constrained and undersampled in the oceans, despite interactions between living organisms and non-living minerals having central roles within many globally relevant biogeochemical processes. Through a combination of method development, basin-scale particulate collection and analyses, modeling, and field experiments, this thesis examines both the distributions of marine particulate trace metals and the underlying processesinputs, scavenging, vertical and horizontal transport, and biotic uptake-in which marine particles participate.I first present the results of an intercalibration exercise among several US laboratories that analyzed filtered particles on shared polyethersulfone filters. We use inter-lab and intra-lab total elemental recoveries of these particles to determine our state of our intercalibration (521% one-sigma inter-lab uncertainty for most elements; 9% intra-lab) and to identify means of future improvement. We also present a new chemical method for complete dissolution of polyethersulfone filters and compare it to other total particle digestion procedures. I then present the marine particulate distributions of the lithogenic elements Al, Fe, and Ti in the North Atlantic GEOTRACES section. Inputs of lithogenic particles from African dust sources, hydrothermal systems, benthic nepheloid layers and laterally-sourced margin influences are observed and discussed. Lithogenic particle residence times, size-fractionation patterns, Ti-mineral speciation, and relationships to biological aggregation processes are calculated and described. A one-dimensional, sizefractionated, multi-box model that describes lithogenic particle distributions is also proposed and its parameter sensitivities and potential implications are discussed.The thesis concludes with the presentation of results from a series of bottle incubations in naturally iron-limited waters using isotopically labeled Fe-minerals. We demonstrate both biotic and abiotic solubilization of the minerals ferrihydrite and fayalite via transfer of isotopic label into suspended particles. These results are the first of their kind to demonstrate that minerals can be a source of bioavailable iron to euphotic communities and that spatial and ecological variations in mineral Fe-bioavailability may exist.Thesis supervisor: Phoebe J. Lam Title: Associate Scientist AcknowledgementsAlthough this thesis has my name on it, every page bears the watermark of my brilliant and ever thoughtful advisor, Phoebe (J.) Lam. Thank you so much for providing me with exciting projects, invigorating afternoon data conversations, prompt and thoughtful written feedback, and what I'm sure was a lifetime's worth of patience over the years. Together we've travelled to the bottom of the world, sampled oceans, and spent nights by the hum of a synchrotron; it's hard to imagine doing rese...

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“…Between each ultra-filtration process, every membrane was rinsed according to the following procedure: 1 L of UHP water, 500 ml of a NaOH 0.1 M solution (to remove organic matter), 1 L of UHP water, 500 ml of a HCl/HNO 3 0.1 M solution (to remove metals), and 1 L of UHP water. The rinsing steps and their importance have been previously described (Ingri et al, 2000;Dahlqvist et al, 2007;Schlosser and Croot, 2008;Dammshäuser and Croot, 2012).…”

Section: Filtration and Ultra-filtrationmentioning

confidence: 99%

“…Following Francioso et al (1996), Ingri et al (2000), Dahlqvist et al (2004), Liu and Lead (2006), Schlosser and Croot (2008), Dammshäuser and Croot (2012) and Liu et al (2013), different parameters resulting from the TFF procedure must be considered and included in equations to determine the concentrations of each ultra-filtered fraction. One important parameter is the retentate volume concentration factor (VCF r ):…”

Section: The Ultra-filtration Parametersmentioning

confidence: 99%

Factors controlling the chemical composition of colloidal and dissolved fractions in soil solutions and the mobility of trace elements in soils

Gangloff

Stille

Schmitt

et al. 2016

Geochimica et Cosmochimica Acta

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Low colloidal associations of aluminium and titanium in surface waters of the tropical Atlantic

Cited by 26 publications

References 85 publications

Thorium distributions in high‐ and low‐dust regions and the significance for iron supply

Thorium distributions in high‐ and low‐dust regions and the significance for iron supply

The biogeochemistry of marine particulate trace metals

Factors controlling the chemical composition of colloidal and dissolved fractions in soil solutions and the mobility of trace elements in soils

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