Integrated mercury cycling, transport, and air-water exchange (MECAWEx) model.

The MECAWEx model (Pirrone et al., 2005) has been tested using measured total gaseous mercury data obtained during the four Mediterranean Atmospheric Mercury Cycle System (MAMCS) project measurement campaigns performed simultaneously at five coastal sites around the Mediterranean between 1998 and 1999. The model has also been tested using Hg-(g)(0), Reactive Gaseous Mercury (RGM) and Total Particulate Mercury (TPM) data from two oceanographic cruise campaigns. The model has been run for the whole 12 month period of the campaigns and thus has allowed annual deposition and emission fluxes to and from the Mediterranean Sea to be estimated. The results show that the combined wet and dry Hg deposition to the sea surface during the model run was 20.4 tons, while the emissions were 90.4 tons making the Mediterranean Sea a net emitter of Hg. The results allow the relative importance of wet and dry deposition pathways to be assessed over the modeling domain. The Mediterranean region as a whole is an area where the dry deposition flux of Hg almost always outweighs the wet deposition flux.