Observational and modeling study of dry deposition on surrogate surfaces in a South China city: implication of removal of atmospheric crustal particles

摘要

Dry deposition samples collected during 1999-2001 at a South China site using surrogate surfaces were analyzed by capillary electrophore-sis. Collector surface properties played important roles to the dry deposition. The deposition velocities for various species ranged from 0.02 to 1.69 cms~(-1), in general agreement with literature values. More than 90% of Ca~(2+) was deposited by sedimentation and its comparable values of dry or wet removal residence times imply that dry deposition is an important atmospheric removal process for the ubiquitous crustal species in South China, compared with precipitation scavenging. Relatively good agreement was found when the species deposition velocities were modeled based on up-to-date knowledge of particle dry deposition. The total depositions for anthropogenic and crustal species in northern China are likely to be much higher than those in the south, including our site where the fluxes of the acidic species SO_4~(2-)rnand NO_3~- were 4.4 and 2.2 g m~(-2) year~(-1), respectively. The sum of dry deposition for cations Na~+, Ca~(2+), Mg~(2+), and K~+ contributes 44% of the total flux, which is equivalent to the value estimated in Europe.