The GMOstral is initiated by a European project GMOS (Global Mercury Observation System), which aims at developing a coordinated global observation system for the global pollutant, atmospheric mercury (Hg). This will then provide high quality data for the validation and application of regional and global scale atmospheric models, to give a firm basis for future policy development and implementation. In this context we propose to implement three Hg monitoring stations in sub-Antarctic and Antarctic sites in order to document and monitor the atmospheric Hg trends in remote places of the southern hemisphere and to study the almost unknown reactivity of Hg in those regions, in particular diurnal cycling, deposition, and reemission trends in Antarctica.