Dry Deposition Velocities of Aerosol Sulphate in Rural Eastern England

Abstract

Dry deposition velocities of aerosol sulphate have been determined by the gradient method, using non-dispersive X-ray flourescence. The measurements were made over periods of several hours, during relatively constant atmospheric conditions, day and night, throughout one year. The median deposition velocity for the whole period was 0.03 cm s⁻¹, a value close to earlier experimental and many theoretical determinations, but considerably less than some recent, short-period, field determinations. Although there is considerable scatter, the deposition velocity varies with atmospheric stability and with the seasons. The dry deposition of aerosol sulphate is much less important than the dry deposition of sulphur dioxide and the wet deposition of sulphate, but is of the same order as the wet deposition of sulphur dioxide.