Elemental gas phase atmospheric mercury as it interacts with the ambient aerosol and its subsequent speciation and deposition

A model describing the interaction of gas phase elemental atmospheric mercury, H-(g)((o)), with the ambient aerosol has been linked to hybrid single-particle Lagrangian integrated trajectory (HYSPLIT_4) a hybrid dispersion and deposition model. The integrated modelling system allows H-(g)((o)) emitted from an anthropogenic source in the presence of the local aerosol to be followed and calculates the deposition fluxes to terrestrial and water receptors resulting from the interaction between the H-(g)((o)) and the aerosol. The model includes a source-based parameterized description of the ambient aerosol, a gas-phase diffusion and adsorption model for the interaction of H-(g)((o)) and the ambient particulate matter under conditions of low relative humidity, and an aqueous phase Hg chemistry model to allow for complete or partial deliquescence of the particles under conditions of high humidity. The model is, thus, able not only to calculate deposition fluxes, but also the speciation of the Hg compounds deposited; this is of great importance in the modelling of the atmospheric Hg cycle due to the difference in the properties of elemental and oxidized Hg. (C) 2000 Elsevier Science B.V. All rights reserved.