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Quantification of the lithogenic carbon pump following a simulated dust-deposition event in large mesocosms


Bressac, M and Guieu, C and Doxaran, D and Bourrin, F and Desboeufs, K and Leblond, N and Ridame, C, Quantification of the lithogenic carbon pump following a simulated dust-deposition event in large mesocosms, Biogeosciences, 11 pp. 1007-1020. ISSN 1726-4170 (2014) [Refereed Article]


Copyright Statement

© Author(s) 2014. Licensed under Creative Commons Attribution 3.0 Unported (CC BY 3.0)

DOI: doi:10.5194/bg-11-1007-2014


Lithogenic particles, such as desert dust, have been postulated to influence particulate organic carbon (POC) export to the deep ocean by acting as mineral ballasts. However, an accurate understanding and quantification of the POC–dust association that occurs within the upper ocean is required in order to refine the "ballast hypothesis". In the framework of the DUNE (a DUst experiment in a low-Nutrient, low-chlorophyll Ecosystem) project, two artificial seedings were performed seven days apart within large mesocosms. A suite of optical and biogeochemical measurements were used to quantify surface POC export following simulated dust events within a low-nutrient, low-chlorophyll ecosystem. The two successive seedings led to a 2.3–6.7-fold higher POC flux than the POC flux observed in controlled mesocosms. A simple linear regression analysis revealed that the lithogenic fluxes explained more than 85% of the variance in POC fluxes. On the scale of a dust-deposition event, we estimated that 42–50% of POC fluxes were strictly associated with lithogenic particles (through aggregation and most probably sorption processes). Lithogenic ballasting also likely impacted the remaining POC fraction which resulted from the fertilization effect. The observations support the "ballast hypothesis" and provide a quantitative estimation of the surface POC export abiotically triggered by dust deposition. In this work, we demonstrate that the strength of such a "lithogenic carbon pump" depends on the biogeochemical conditions of the water column at the time of deposition. Based on these observations, we suggest that this lithogenic carbon pump could represent a major component of the biological pump in oceanic areas subjected to intense atmospheric forcing.

Item Details

Item Type:Refereed Article
Keywords:carbon export, lithogenic carbon pump, surface ocean
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:131078
Year Published:2014
Web of Science® Times Cited:42
Deposited By:Ecology and Biodiversity
Deposited On:2019-02-28
Last Modified:2019-04-26
Downloads:36 View Download Statistics

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