Constraints on the source of reactive phases in sediment from a major Arctic river using neodymium isotopes ...

Riverine suspended particulate matter (SPM) is essential for the delivery of micronutrients such as iron (Fe) to the oceans. SPM is known to consist of multiple phases with differing reactivity, but their role in the delivery of elements to the oceans is poorly constrained. Here we provide new const...

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Bibliographic Details
Main Authors: Larkin, Christina, Piotrowski, Alex, Hindshaw, Ruth, Bayon, Germain, Hilton, Robert, Baronas, Jotautas, Dellinger, Mathieu, Wang, Ruixue, Tipper, Edward
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2021
Subjects:
iron oxides
bioavailable
neodymium isotopes
Arctic
Arctic Ocean
Mackenzie River
Mackenzie river
Online Access:https://dx.doi.org/10.17863/cam.72226
https://www.repository.cam.ac.uk/handle/1810/324773
Description
Summary:Riverine suspended particulate matter (SPM) is essential for the delivery of micronutrients such as iron (Fe) to the oceans. SPM is known to consist of multiple phases with differing reactivity, but their role in the delivery of elements to the oceans is poorly constrained. Here we provide new constraints on the source and composition of reactive phases in SPM from the Mackenzie River, the largest sediment source to the Arctic Ocean. Sequential leaching of SPM shows that river sediments contain labile Fe phases. We estimate the labile Fe flux is substantial (0.21(+0.06,-0.05) Tg/yr) by quantifying Fe concentrations in weak leaches of the SPM. The labile Fe phase hosts a considerable amount of rare earth elements (REE), including neodymium (Nd). We demonstrate that the labile Fe phase and dissolved load have radiogenic Nd isotope ratios that are identical within uncertainty, but up to 8 epsilon units distinct from the silicate phase. We interpret this as evidence for dynamic cycling between Fe-oxide phases in ...

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