Carbon sequestration in the deep Atlantic enhanced by Saharan dust

Pabortsava, Katsiaryna; Lampitt, RS; Benson, Jeff; Casciotti, K; Crowe, Christian; McLachlan, Robert; le Moigne, F; Moore, CM; Pebody, Corinne; Provost, Paul; Rees, AP; Tilstone, GH; Woodward, EMS. 2017 Carbon sequestration in the deep Atlantic enhanced by Saharan dust. Nature Geosciences. 10.1038/ngeo2899

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sinking rates of particulate organicmatter. Here we present a two-year time series of sediment trap observations of particulate organic carbon flux to 3,000m depth, measured directly in two locations: the dust-rich central North Atlantic gyre and the dust-poor South Atlantic gyre. We find that carbon fluxes are twice as high and a higher proportion of primary production is exported to depth in the dust-rich North Atlantic gyre. Low stable nitrogen isotope ratios suggest that high fluxes result from the stimulation of nitrogen fixation and productivity following the deposition of dust-borne nutrients. Sediment traps in the northern gyre also collected intact colonies of nitrogen-fixing Trichodesmium species. Whereas ballast in Enhanced atmospheric input of dust-borne nutrients and minerals to the remote surface ocean can potentially increase carbon uptake and sequestration at depth. Nutrients can enhance primary productivity, and mineral particles act as ballast, increasing the southern gyre is predominantly biogenic, dust-derived mineral particles constitute the dominant ballast element during the enhanced carbon fluxes in the northern gyre. We conclude that dust deposition increases carbon sequestration in the North Atlantic gyre through the fertilization of the nitrogen-fixing community in surface waters and mineral ballasting of sinking particles.

Item Type: Publication - Article
Subjects: Biology
Marine Sciences
Divisions: Plymouth Marine Laboratory > National Capability categories > Atlantic Meridional Transect
Depositing User: Malcolm Woodward
Date made live: 10 Mar 2017 15:51
Last Modified: 06 Jun 2017 16:18

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