A comprehensive Eulerian modelling framework for airborne mercury species:model development and applications in Europe

A comprehensive mercury model system using the Eulerian reference frame of the Acid Deposition and Oxidant Model (ADOM) has been developed under the C anada-Germany Science & Technology Go-operation Agreement and applied withi n the European Union MArine Science and Technology-BAltic Sea SYstem Study (MAST-III-BASYS) and the Environment & Climate project Mercury Species over Europe (MOE), to study the regional transport and deposition fluxes of atm ospheric mercury species. The model is able to simulate long-range transpor t of mercury over the entire depth of the troposphere with a basic time ste p of I h and incorporates current knowledge of physicochemical forms and tr ansformation reactions of atmospheric mercury species. Model predicted conc entration and deposition pattern of mercury species over Europe are present ed and concentrations of total gaseous mercury in ambient air and total mer cury in precipitation calculated by the model are compared with observed va lues from a BASYS monitoring network study in February/March 1998. Concentr ations in air agree within a factor of about 2 with observed values, thus i ndicating that the model is capable of reproducing observations satisfactor ily even on an hourly basis. Observed monthly average concentrations in pre cipitation at four monitoring stations at the Baltic Sea coast are reproduc ed by the model within a factor of 1.3 suggesting that the chemical scheme in the model is based on an adequate parameterisation of aqueous phase chem istry. (C) 2001 Elsevier Science Ltd. AH rights reserved.