Dissolved Al in the surface and subsurface waters of the North Atlantic during the US GEOTRACES cruises.
Abstract
The 2010 and 2011 US GEOTRACES cruises provided an opportunity to produce a highly detailed section of the concentrations of dissolved Al across the N Atlantic between 22 and 70W and 17-37N. Along this transect, surface water dissolved Al concentrations, which reflect the deposition and partial dissolution of aluminosilicate mineral dust, show a gradient indicating lower rates of dust deposition in the eastern Atlantic despite Saharan dust supply originating in the eastern side of the basin. This apparent anomalous distribution is believed to be a result of both atmospheric and surface water circulation processes. In the subsurface waters of the eastern basin, the Mediterranean outflow (1300 m) is clearly delineated by its elevated Al signal, resulting from the intense deposition of eolian materials to the surface Mediterranean source waters. The elevated dissolved Al signal at 300m in the western basin is coincident with the classic 18 degree subtropical mode water, and traces another route whereby this surface originating signal can enter the subsurface waters. An entirely different source of dissolved Al is seen entering the deeper waters of the Atlantic at the station occupied in the axial valley of the Mid Atlantic Ridge (MAR) near the TAG hydrothermal site. Here, elevated dissolved Al values of over 40 nM are seen in the buoyant hydrothermal plume and their effect of this input is visible in the elevated deep water concentrations of the nearby stations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMOS24E..01M
- Keywords:
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- 0312 ATMOSPHERIC COMPOSITION AND STRUCTURE / Air/sea constituent fluxes;
- 0489 BIOGEOSCIENCES / Trace element cycling;
- 4875 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Trace elements