Iron solubility in crustal and anthropogenic aerosols: The Eastern Mediterranean as a case study

We report seawater dissolution experiments for aerosol samples simultaneously collected (October 2007) across the Levantine Basin (LB, Eastern Mediterranean Sea), a marine system influenced by seasonal atmospheric inputs. Two distinct populations exhibited contrasting kinetic profiles; those representative of strong Saharan dust events which had variable iron release profiles with a maximum solubility of 0.94 ± 1.48% (1 s.d.) whereas those which had a relatively greater anthropogenic influence had consistent profiles (fast release, ≤2 h, of dissolved iron in seawater followed by removal) with a maximum solubility of 11.5 ± 9.3% (1 s.d.). First estimates of atmospheric fluxes of soluble iron are presented, ranging from 8.64 ± 10.76 mg m−2 y−1 for the Northern LB to 6.48 ± 7.78 mg m−2 y−1 for the Southern LB. Estimates of Fe fluxes to oceanic basins are important for constraining the global iron budget, and dust dissolution kinetic profiles provide information on the mechanisms involved during the release of aerosol Fe in seawater post atmospheric deposition.

► Iron essential limiting micronutrient in ocean.
► Aerosol depositions dominant external source to the surface open ocean.
► Iron solubility poorly constrained.
► Determination of kinetics of dissolution and solubility from aerosols.
► First estimate of dry atmospheric inputs of soluble iron over Levantine Basin.