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Post-depositional processes: what really happens to new atmospheric iron in the oceanís surface?


Bressac, M and Guieu, C, Post-depositional processes: what really happens to new atmospheric iron in the ocean's surface?, Global Biogeochemical Cycles, 27, (3) pp. 859-870. ISSN 0886-6236 (2013) [Refereed Article]


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Copyright 2013 American Geophysical Union

DOI: doi:10.1002/gbc.20076


[1] Abiotic iron removal processes such as scavenging can significantly and rapidly modify iron distribution in the dissolved‐colloidal‐particulate continuum. Therefore, these processes could be considered, in addition to ligand complexation, as a major control on atmospheric iron dissolution in seawater. In this work, we investigated the seasonal abiotic processes occurring once dust deposited on surface seawater using a series of artificial seeding experiments (allowing us to take into consideration the settling of particles on a 1 m depth layer). Here, we demonstrate that atmospheric dissolved iron concentration ([DFe]) is driven by the processes governed by the dissolved organic matter (DOM) pool. Following artificial dust seeding, an order magnitude range increase in the [DFe] (12 Ė 181 nmol L−1) was observed depending on the season. Under high and fresh DOM conditions (spring and summer), the rapid formation of aggregates induced a negative feedback on the [DFe] through scavenging, while a fraction of the DFe was likely organically complexed. In contrast, in low‐DOM surface waters (winter), aggregation was not observed, allowing a very large transient increase in [DFe] (181 nmol L−1) before being removed by adsorption onto settling particles. A key result of the findings is that depending on the age and quantity of DOM, the "lithogenic carbon pump" is likely a major pathway for organic carbon export. Modeling studies should therefore relate both atmospheric iron dissolution in seawater and the intensity of the subsequent biological response, to the age and quantity of DOM.

Item Details

Item Type:Refereed Article
Keywords:atmospheric deposition, dissolved iron, surface ocean, post-depositional processes
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Oceanography not elsewhere classified
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Oceanic processes (excl. in the Antarctic and Southern Ocean)
UTAS Author:Bressac, M (Dr Matthieu Bressac)
ID Code:131077
Year Published:2013
Web of Science® Times Cited:24
Deposited By:Ecology and Biodiversity
Deposited On:2019-02-28
Last Modified:2019-03-13
Downloads:54 View Download Statistics

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