Dust deposition to the East China Sea and its biogeochemical implications

Abstract

Atmospheric Al concentrations published by Hsu et al. (2008) are used together with new information on mass particle‐size distributions (MSDs) to calculate dust deposition to northern Taiwan and to evaluate the significance of the process for the East China Sea (ECS). Seasonal variations in aerosol Al in northern Taiwan show maxima in spring and winter and minima in summer and fall. The MSD of Al and Fe is monomodal, with a mean mass median diameter of 3.6 ± 1.2 μm, and the dry deposition velocity integrated over the entire MSD is 2.0 ± 1.5 cm s−1. The estimated dust deposition to the ECS is ∼20 g m−2 a−1, with wet deposition accounting for three fourths of the total. The quantity of dust deposited decreases exponentially with distance from the source regions. The annual dust input to the entire ECS is estimated to be ∼17 Mt, and when compared with riverine discharge, dust deposition appears to be a significant source of sediments and dissolved Fe. The large quantities of dust deposited also could have significant implications for the biogeochemical cycling of Fe (and Al), including effects on phytoplankton populations.