High resolution dissolved and dissolvable aluminum measurements along the GEOVIDE section (GEOTRACES section GA01)

One of the main aims of the GEOTRACES programme is to investigate the distribution and cycling of key trace elements in the world oceans. Primary importance is given to tracers of oceanic and atmospheric processes, such as dissolved aluminum, which is used to estimate dust deposition rates to the ocean (Measures & Brown, 1996). For this study, samples for dissolved (filtered on 0.2 µm) and dissolvable (unfiltered) Al were collected in the water column at 32 stations in the North Atlantic Ocean along the GEOVIDE section. In addition, high resolution surface water sampling was undertaken. The transatlantic section sampled key areas of the thermohaline circulation, including the Iberian abyssal plain, West European basin, Reykjanes Ridge, Irminger Sea, Greenland margin and Labrador Sea. The transect allowed us the opportunity to assess the influence of outflow waters, boundary currents, shelf and deep water exchanges, hydrothermal vents and scavenging processes on the distribution of dissolved and disolvable dAl.

Sample analysis was undertaken using a fluorometric technique with flow injection (Brown&Bruland 2008) and validated through SAFE and GEOTRACES reference seawater analysis.

The results have provided insights into the sources and distribution of dissolved and dissolvable Al in the North Atlantic and the micronutrient aerosol deposition rates inferred from the dissolved Al measurements.