Nicola Pirrone CNR Institute of Atmospheric Pollution Research, Rome, Italy pirrone@iia.cnr.it
Mercury is ubiquitous in the atmosphere, it has ground level background concentrations which are almost constant over hemispheric scales; the southern hemisphere having a slightly lower concentration than the northern. Recent measurements of free tropospheric air, from high altitude sites and from measurements made on board of aircrafts indicate that its concentration changes little up to the tropopause. In the stratosphere mercury has been identified associated with the stratospheric aerosol. The transport of mercury, therefore, occurs in the boundary layer, in the free troposphere and stratosphere; the fate of mercury, therefore, is determined by the different chemical environments that these regions of the atmosphere represent, the different physical and meteorological processes which occur in them and also by exchange between them (Pirrone et al., 2008; Lindberg et al., 2007). The impact of energy resources exploitation, especially fossil fuel exploitation, on ecosystems in terms of mercury contamination is threefold. Firstly, because fossil fuel-power plants are the highest emitting anthropogenic source of mercury released annually to the atmosphere. Secondly, because the other pollutants emitted as a result of fossil fuel combustion, such as NOx and SO2, have an impact on the atmospheric chemistry of mercury and influence its deposition patterns. While the previous two impacts are observable in the short term, the third is the medium to long term impact that exploitation of fossil fuels has on atmospheric mercury cycling, as a result of the release of greenhouse gases which contribute to climate change (Pirrone et al. 2008; Eisenreich et al. 2005).
Improved information on emissions, particularly emissions in Europe and North America, have contributed to further progress in assessment of the regional impacts of mercury on terrestrial and aquatic environments (Pirrone et al. 2008; Pirrone and Mason, 2009). Major international activities to assess source-receptor relationships for mercury in the environment are developed as part of international conventions (i.e., UNECE-LRTAP, OSPAR, HELCOM) and programmes (i.e., EU projects, ACAPs, GEO, UNEP, IGBP). Policy makers in Europe have also taken the advantage of improved information on emissions to assess the effectiveness of measures aimed to reduce the impact of this highly toxic contaminant on human health and ecosystems. Following the preparation of the EU Position Paper on Ambient Air Pollution by mercury (Pirrone, N. and Wichmann-Fiebig, M., 2003; Pirrone et al., 2001; http://ec.europa.eu/environment/air/quality/ background.htm), the EU adopted the European Mercury Strategy which was aimed to phase out the use of mercury in goods and industrial applications and reduce to the extent possible mercury emissions to the atmosphere from fossil fuels power plants and industrial facilities. In 2002 UNEP Chemicals released the first assessment (Global Mercury Assessment Report, GMA) on global mercury contamination (UNEP, 2002). Since then, a number of activities have been developed in order to support the achievement of objectives set by the UNEP Governing Council (decisions 23/9 IV in 2005, 24/3 IV in 2007, 25/IV in 2009) to continue and elaborate possible strategies and mechanisms aimed to phase out the use of mercury in a wide range of products and reduce, to the extent possible, the emissions from industrial plants.
The lecture will highlight major advances made in recent years and current gaps in our knowledge of different processes affecting the transport and transformations of mercury in the atmosphere, its dynamics at the air-ocean / terrestrial interfaces, its major emission sources, both natural and anthropogenic, and how the research community is supporting the development of new legislative frameworks (i.e., under the UNEP Mercury programme through the partnership areas), the revision of existing conventions (i.e., UNECE-LRTAP through the Task Force on Hemispheric Transport of Air Pollutants) and development of on-going programmes (i.e., GEO / GEOSS through the Task HE-09-02d aimed to develop a global monitoring observation system for mercury).
References:
Pirrone, N. (2001) Mercury Research in Europe: Towards the preparation of the New EU Air Quality Directive. Atmospheric Environment, 35, 2979-2986.
Pirrone, N. and Wichmann-Fiebig, M. (2003) Some Recommendations on Mercury Measurements and Research Activities in the European Union. Atmospheric Environment, 37/S1, 3-8.
Eisenreich, S. J., Bernasconi, C., P. Campostrini, A. De Roo, G. George, A.-S., Heiskanen, J. Hjorth, N. Hoepffner K.C. Jones, P. Noges, N. Pirrone, N. Runnalls, F. Somma, N. Stilanakis, G. Umlauf, W. van de Bund, P. Viaroli, J. Vogt, J.-M. Zaldivar. (2005) Climate Change and the European Water Dimension. A Report to the European Water Directors 2005. EU Report No. 21553, European Commission- Joint Research Centre (Publisher), Ispra, Italy, pp. 253.
Pirrone, N., I. M. Hedgecock, F. Sprovieri (2008) New Directions: Atmospheric mercury, easy to spot and hard to pin down: impasse? Atmospheric Environment, 42, 8549–8551.
Pirrone, N. and R. Mason (2009) Mercury Fate and Transport in the Global Atmosphere: Emissions, Measurements and Models. Springer, USA, pp. 637 (DOI10.1007/978-0-387-93958-2)
