Sulfate dry deposition fluxes and overall deposition velocities measured with a surrogate surface

Abstract

Previous studies have shown that the dry deposition of particulate sulfate can account for a significant fraction of its total (wet+dry) deposition. However, there is no generally accepted method to directly measure dry deposition. In this study, the particulate sulfate dry deposition was measured using a smooth surrogate surface between September 2000 and June 2001 in Izmir, Turkey. Concurrently, ambient air samples were collected. Average particulate sulfate fluxes and ambient concentrations were 49.3±24.3 mg m −2 d −1 and 11.2±6.6 μg m −3, respectively. The measured particulate dry deposition fluxes were higher than those measured in other urban and rural areas. The contribution of marine and terrestrial sources was also estimated and found to be insignificant. The particulate phase overall dry deposition velocities calculated using the dry deposition fluxes and corresponding ambient concentrations averaged 6.3±3.9 cm s −1. This value is higher than values typically used to estimate particulate sulfate deposition; however, it is in good agreement with values determined using similar surrogate surface techniques.