Int. Workshop on Harmonization of Mercury Measurements Methods and Models to Assess Source-Receptor Impact on Air Quality and Human Health

A significant amount of research indicates that natural and human (anthropogenic) activities can redistribute mercury in the atmospheric, soil and water ecosystems through a complex combination of transport and transformation processes.

Advances have been made in understanding key mechanisms affecting atmospheric mercury cycle. However, our current understanding of several key processes influencing the cycling of mercury in the environment is presently not sufficient for quantitative descriptions and thus neither for modelling. Although decreasing trends in atmospheric deposition with decreasing atmospheric emissions have been observed due to the complex mechanisms involved in the mercury cycle, a linear relationship between mercury deposition and methylmercury levels in fish does not exist. Moreover, recent studies carried out in different coastal areas and open seas regions have shown that marine ecosystems can act as both a source and a sink in the global mercury cycle depending on meteorological conditions and numerous environmental factors.

With the above in mint one may wish to ask what are the qualitative and quantitative relationships between atmospheric input and the Hg in aquatic environments? Is it possible to establish a deposition limit for mercury in order to regulate its emissions to the atmosphere? Do we know the relationship between the flux of mercury entering surface waters and the level of mercury (methyl mercury) found in fish? How is it possible to evaluate the response time of the marine ecosystem in relation to changes in atmospheric emissions? Are any regional/hemispherical modelling frameworks validated and tested for assessing temporal and spatial patterns of mercury deposition to marine waters and its subsequent accumulation in the fish and ultimately its impact on the food chain? At the present time, we do not know the answers to these questions, but scientists, in many countries, are engaged in studies that could lead in the future to an improved understanding of the fate and transport of mercury.

The international workshop, organised by the Institute for Atmospheric Pollution of the Italian National Research Council (CNR-IIA) and the US-Environmental Protection Agency, will bring together leading scientists from two mutually dependent but quite different fields, source term and transport scientists with human health and toxicology specialists, to facilitate liaison among them. It is, indeed, very important to harmonize methods in each of these research areas, and bring about better understanding of critical data gaps and needs so that informed, cooperative interdisciplinary work can occur in future. The product will be a report to be submitted as contribution to the next UNEP Governing Council to be held in 2005 and to the International Conference on Mercury as Global Pollutant (to be held in Slovenia in July 2004). The report will be used as a background document or white paper informing everyone about the state of our understanding concerning atmospheric speciated monitoring and modelling, and health.