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Physical speciation and solubility of iron from baleen whale faecal material


Ratnarajah, L and Lannuzel, D and Townsend, AT and Meiners, KM and Nicol, S and Friedlaender, AS and Bowie, AR, Physical speciation and solubility of iron from baleen whale faecal material, Marine Chemistry, 194 pp. 79-88. ISSN 0304-4203 (2017) [Refereed Article]

Copyright Statement

Copyright 2017 Elsevier B.V.

DOI: doi:10.1016/j.marchem.2017.05.004


Primary productivity in large areas of the Southern Ocean is limited by the availability of a key micronutrient—iron (Fe). Recently it has been suggested that marine animals could play an important role in recycling Fe through their diet and subsequent defecation, however there is no information on the relative bioavailability of faecal Fe for uptake. The bioavailability of Fe in seawater is controlled by a number of complex interactions. The physical separation between the dissolved (< 0.2 μm) and particulate (> 0.2 μm) fractions is one common measure used to determine element bioavailability. Here, the size fractionation of Fe from 3 whale faecal samples in 4 different size classes (< 0.2 μm, 0.2–10 μm, 10–60 μm and > 60 μm) was investigated, along with the leaching of particulate Fe over time. Although the total particulate fraction (> 0.2 μm, 5026–22,526 nmol L−1) dominated the total Fe pool, the concentrations of dissolved Fe in whale faecal samples (186–754 nmol L−1) were three order of magnitude higher than published Southern Ocean surface seawater concentrations. Furthermore, results from the leaching experiment suggest that Fe is continually leached from faecal particles over an initial 12-hour period, thus increasing the concentration of bioavailable Fe in surface seawater. Although the concentrations measured here are some of the highest reported in the literature, the true supply of Fe back to surface seawater will be controlled by processes such as organic complexation, scavenging and sinking by particles, remineralisation, and vertical transport, not measured in this study.

Item Details

Item Type:Refereed Article
Keywords:iron, baleen whales, faecal material, physical speciation, solubility, dissolved iron, particulate iron, Southern Ocean, biological recycling
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical oceanography
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Measurement and assessment of marine water quality and condition
UTAS Author:Ratnarajah, L (Ms Lavenia Ratnarajah)
UTAS Author:Lannuzel, D (Associate Professor Delphine Lannuzel)
UTAS Author:Townsend, AT (Associate Professor Ashley Townsend)
UTAS Author:Meiners, KM (Dr Klaus Meiners)
UTAS Author:Nicol, S (Dr Stephen Nicol)
UTAS Author:Bowie, AR (Professor Andrew Bowie)
ID Code:121010
Year Published:2017
Web of Science® Times Cited:10
Deposited By:Oceans and Cryosphere
Deposited On:2017-09-06
Last Modified:2018-05-24

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