Estimation of dry deposition fluxes of particulate species to the water surface in the Qingdao area, using a model and surrogate surfaces

Measurements of dry deposition flux to surrogate surfaces were made in Qingdao in July 2001 and March 2002, and airborne concentration measurements of Fe, Al, Cu, Pb, Zn and Cd were made from April 2001 to May 2002 to determine atmospheric inputs of pollutants to the coastal waters. Size-dependent particle dry deposition velocities were obtained using Williams’ model with meteorological inputs from past observations, taking into account the particle growth in the humid region near the air/sea interface. Sensitivity tests show that the model provides deposition velocities comparable with recent reference values. A comparison of the modeled dry deposition fluxes with measurements and GESAMP (Group of Experts on Scientific Aspects of Marine Pollution) suggestions demonstrated that the current Williams’ model produced reasonable results. Using the averages of measured concentrations of six metal elements, the dry deposition fluxes for four seasons in the Qingdao area were calculated. The results showed that the deposition fluxes of crustal elements Al, Fe and Mn in spring and winter account for more than 70% of the whole year's deposition, while fluxes of Cu, Pb and Zn in autumn and winter contribute more than 70% of the whole year's deposition.