Reactivity of atmospheric aerosols under conditions typical for haze

摘要

Aqueous atmospheric particles in different forms (e.g.,rain,cloud,fog,deliquescent aerosols) play a major role in controlling atmospheric chemical and physical processes.The most important transformation is oxidation of dissolved SO2 to sulfate (Seinfeld and Pandis,1998).Since hygroscopic compounds constitute an important fraction of aerosols either of continental or marine origin,stable aqueous droplets form even at relative humidity below 100 % (Meszaros,1999).The deliquescence point as well as the amount of condensed water depends on the chemical composition and consequently on the size of atmospheric particles (Pilinis et.al,1989;Tang and Munkelwitz,1993).Because trace gases present in a polluted atmosphere (e.g.,SO_2,NO_X,NH_3) dissolve in the aqueous solution formed at deliquescence,the formation of secondary aerosol material can occur even at conditions typical for haze.In these concentrated solutions,many reaction pathways are not understood.According to recent investigations,even the surface structure of highly concentrated inorganic salt solutions may control the transformation of certain atmospheric trace gases,with SO_2 probably being one of them (Knipping et.al.,2000).