Impact of surface ocean conditions and aerosol provenance on the dissolution of aerosol manganese, cobalt, nickel and lead in seawater

Fractional solubilities over the range of samples and conditions tested were in the range of 50-104% for Mn, 29-58% for Co, 40-85% for Ni and 67-112% for Pb. A large proportion (36-100%, median 89%) of the total dMn, dCo, dNi and dPb was mobilised rapidly during the first leaching step (5 min), with less dTM being released in leaches 2 through 4. Furthermore, investigation of the size distribution of the aerosol-derived trace metals in seawater showed that dissolved Pb was mostly colloidal (0.02-0.4 μm), dissolved Mn and Co were mostly soluble (< 0.02 μm), and dissolved Ni displayed a mixed size distribution. Good empirical relationships were observed between enrichment factors for aerosol antimony (Sb) and the fractional solubilities of aerosol Fe, Co and Pb, suggesting total aerosol Sb can be useful in estimating and modelling the fractional solubility of these metals using total aerosol trace metal concentrations from historical data.