Atmospheric speciation of ionic organotin, organolead and organomercury compounds in NE Bavaria (Germany)

Organotin (OTC), organolead (OLC) and organomercury (OMC) compounds are highly toxic and exhibit a potential negative effect on terrestrial ecosystems. Individual ionic OTC, OLC and OMC compounds were identified and their concentrations determined in the gas phase, aerosol particles, and bulk precipitation at a rural (Waldstein) and an urban (Bayreuth city) site in NE-Bavaria. At both sites, butyltins, methyltins, octyltins, trimethyllead and monomethylmercury concentrations in the gas phase were < 100 pg m(-3) (determined as corresponding Sn, Pb and Hg concentrations, respectively) with the dominance of tri- and di-substituted OTC and octyltins. The same species were found in bulk precipitation with concentrations < 25 ng l(-1) (Sn, Pb, Hg) with the dominance of mono- substituted OTC. In aerosols, only butyltins, dimethyltin and monomethyltin (< 500 pg Sn m(-3)) were found and mono-substituted OTC predominated. No significant difference of concentrations of organometallic compounds in the atmosphere at the two sites was found. For OTC, the washout factors was in the order: mono- greater than or equal to di- > tri-substituted OTC, and the gas/particle partition coefficients were mono- > di- > tri-substituted OTC. The distribution spectrum of OTC in aerosols showed the strong linkage of OTC to the long-lived particles and high accumulation of OTC in the filter at the Waldstein site. The results indicate that long-range-transport of organometallic compounds in the atmosphere is an important source at our both sites. Aerosol particles may serve as a sink in the chemical cycles of OTC in the atmosphere, especially for monomethyltin and monobutyltin. (C) 2004 Elsevier Ltd. All rights reserved.