Atmospheric particle dry deposition of major ions to the South Atlantic coastal area observed at Baia de Todos os Santos, Brazil

The coastal atmosphere adjacent to large urban areas can be strongly affected by the emission of air pollutants, among them, major ions species. In this study, the chemical composition and sources of carboxylates and other water-soluble ions in fine and coarse aerosols as well as estimates of particle dry deposition fluxes were studied at a tropical coastal site affected by an urban environment. The mean concentrations of the total carboxylates were 78 ng m(-3) in fine fraction and 81 ng m(-3) in coarse fraction of particulate matter ( PM). The corresponding values for the total inorganic ions were 2143 ng m-3 and 4880 ng m(-3) respectively. Main sources for fine particles were: (i) photochemical formation of carboxylic acids in vapor phase and a posterior gas-to-particle conversion onto sea salt particles; (ii) emissions from anthropic sources with long range transportation processes; and (iii) the interchanging of volatile species among atmospheric phases. In turn, for coarse particles, the predominant sources were: ( i) gas-phase species and ab/adsorbed onto preexisting particles afterwards; ( ii) primary emission of coarse particles from anthropogenic sources; and ( iii) sea salt spray and/or soil resuspension. Finally, particle dry deposition was a very important mechanism representing air-to-sea fluxes of major species.