Mercury, primarily because of its existence and bioaccumulation as methylmercury in aquatic organisms, is a concern for the health of higher trophic level organisms, or to their consumers. This is the major factor driving current research in mercury globally and in environmental regulation, and is the driver for the current UNEP Global Partnership for Mercury Transport and Fate Research (UNEP F&T) initiative. The overall focus of the UNEP F&T report is to assess the relative importance of different processes/mechanisms affecting the transfer of mercury (Hg) from emission sources to aquatic and terrestrial receptors and provide possible source-receptor relationships. This transfer occurs through atmospheric transport, chemical transformations and subsequent deposition, and involves the intermittent recycling between reservoirs that occurs prior to ultimate removal of Hg from the atmosphere. Understanding the sources, the global Hg transport and fate, and the impact of human activity on the biosphere, requires improved knowledge of Hg movement and transformation in the atmosphere. An improved understanding of Hg emission sources, fate and transport is important if there is to be a focused and concerted effort to set priorities and goals for Hg emission management and reduction at the national, regional and global levels; and to develop and implement such policies and strategies. To achieve this, a series of coordinated scientific endeavors focused on the estimation of sources, measurement and validation of concentrations and processes, and modeling, coupled with interpretation of the results within a policy framework, is likely to be required.

Nicola Pirrone is Director of the Institute for Atmospheric Pollution of the Italian National Research Council (CNR-IIA) and Adjunct Professor at the Department of Environmental and Health Sciences of the University of Michigan. He is Chair of the UNEP Global Partnership for Mercury Air Transport and Fate Research, Chair of the WG on Global Atmospheric Mercury Models Intercomparison within the Task Force on Hemispheric Transport of Air Pollutants (TF HTAP) of the UN-ECE-LRTAP convention and Chair of the CEN-TC264 WG that is preparing the European Standard Methods for monitoring mercury concentrations in ambient air and precipitations. He has been Chair of the European WG that prepared the "Air Quality Position Paper on Mercury" that is one of the scientific background documents of the Forth Air Quality Daughter Directive of the European Union. He has published over 100 peer-reviewed articles on different topics associated to atmospheric transport, chemistry and policy relevant issues related to major at-mospheric pollutants.

Robert Mason is a Professor at the University of Connecticut with a joint appointment in the Departments of Marine Sciences and Chemistry. His research focus is the cycling of mercury in the biosphere with emphasis on the atmosphere and on air-sea exchange and redox reactions in the atmospheric boundary layer and the surface ocean. In addition, his research has a focus on mercury methylation in coastal ecosystems and other environments. Mason has an active research group with currently 4 PhD students and a post-doc. He is the author/coauthor of about 100 papers on mercury and is actively involved in a number of national and international mercury initiatives. Mason obtained his undergraduate and Master's degree in South Africa and his PhD at the University of Connecticut in 1991. He was a professor at the University of Maryland before returning to the University of Connecticut in 2005.