Overview of the dissolved iron, manganese and aluminium distributions along the North Atlantic GEOTRACES GA03 section

Three trace elements distributions (iron, manganese and aluminium) help to constrain the sources of chemical elements in the North Atlantic Ocean. Atmospheric, Mediterranean Sea and margin inputs are confirmed while the importance of the hydrothermal venting is revealed.

Hatta, Measures and co-workers (2014, see references below) established an overview of dissolved iron, manganese and aluminium (dFe, dMn and dAl respectively) distributions (see figures below) along the North Atlantic GA03 GEOTRACES section. Elevated dFe concentrations correlate with elevated dAl ones in the surface waters of the subtropical gyre, confirming a substantial atmospheric source for both tracers. But this is not the case for dMn. Sedimentary inputs from margins concern the three tracers but are mostly revealed from elevated dMn signals in the eastern basin, particularly near the African coast and in the western basin, along the advective flow path of the Upper Labrador Sea Water.

The most striking results are found in the neutrally buoyant hydrothermal plume sampled over the Mid-Atlantic Ridge. There the largest dFe anomaly (~68 nM), a dMn anomaly (up to ~33 nM) and large amount of Al (up to 40nM) are detected, with signals visible for ~500 km to the west of the ridge.

Figure. Distribution of dissolved iron (upper), aluminiun (middle) and manganese (lower) along the North Atlantic GA03 GEOTRACES section. Warm colours (red, orange, etc.) indicate high concentrations. Click here to view the figure larger.

References :

Hatta, M., Measures, C. I., Wu, J., Roshan, S., Fitzsimmons, J. N., Sedwick, P., & Morton, P. (2014). An overview of dissolved Fe and Mn Distributions during the 2010–2011 U.S. GEOTRACES north Atlantic Cruises: GEOTRACES GA03. Deep Sea Research Part II: Topical Studies in Oceanography, In Press. doi:10.1016/j.dsr2.2014.07.005 Click here to view the paper.

Measures, C., Hatta, M., Fitzsimmons, J., & Morton, P. (2014). Dissolved Al in the zonal N Atlantic section of the US GEOTRACES 2010/2011 cruises and the importance of Hydrothermal inputs. Deep Sea Research Part II: Topical Studies in Oceanography, In Press. doi:10.1016/j.dsr2.2014.07.006 Click here to view the paper.