9633207 Mason Mercury is one of the few metals which can be said to be a pollutant on a global scale. Anthropogenic inputs of gaseous Hg0 to the atmosphere, estimated to be three to four times the natural terrestrial flux, reach even the remote ocean due to the slowness of Hg0 oxidation in the effective transport of atmospheric Hg), the most important source of Hg in the oligotrophic ocean is aeolian deposition of oxidized Hg scavenged from the atmosphere. One of the key reactions which determines the global fate of anthropogenic Hg is the reduction of aeolian deposits of oxidized Hg2+ to Hg0 in the ocean. Evidence that the reduction of Hg2+ in marine waters occurs in the euphotic zone produced in fresh, estuarine and ocean surface waters at rates which are quite variable (0.2 to 10% per day) by mechanisms which are poorly understood. This work will seek to determine the mechanisms which are environmentally significant and the conditions under which Hg is reduced and oxidized in natural waters. Hg2+ reduction is likely to be a complex process, necessitating both an in-depth understanding of photochemical reactions in natural waters and experience studying the interaction of trace metals with bota. The approach will uniquely combine abiotic photochemical studies and estimates of biologically medicated Hg2+ reduction rates at realistic trace concentrations of Hg2+.
