Temporal changes in the biogeochemistry of Mn, Fe and Al after an artificial dust deposition to large mesocosms (DUNE project)

The deposition of atmospheric dust is the main external source to the ocean for elements abundant in crustal rocks such as Mn, Al and Fe. Once deposited the residence time of these elements in surface waters differs according to their chemical speciation and biological ultilization. In the present work we examined the temporal changes (a daily cycle) in the concentrations within trace metal clean mesocosms after the input of simulated aeolian dust to surface waters of the northwestern Mediterranean. Two artificial deposition events were performed during the course of this experiment: each artificial Saharan dust fertilization to the mesocoms mimicked a wet deposition of 10 g m-2 and the changes in Mn, Fe and Al chemistry were followed over the following week. In this presentation we will present results from this mesocosm experiment focusing on the similarities and differences between these 3 elements. This trace metal dataset makes a significant contribution to enhance our knowledge about the release of trace metals from Saharan dust in a low nutrient low chlorophyll area and the subsequent processes of biouptake and scavenging