ABSOLUTE DEPOSITION MAPS OF HEAVY METALS FOR EUROPE BASED ON MOSS SURVEYS

Torunn Berg¹, Åke Rühling² and Eiliv Steinnes³

¹Norwegian Institute for Air Research, P.Box 100, N-2007 Kjeller, Norway

Phone +47 63 89 82 49, Fax: +47 63 89 80 50, E-mail: torunn.berg@nilu.no

²Ekokonsult AB, Ekologi och miljövård, Bangatan 8, 222 21 Lund.

³Norwegian University of Science and Technology, Trondheim, Norway

The aims of the following project have been to

· Produce absolute deposition maps of heavy metals for Europe

· To provide basic information for modellers and other groups working with heavy metals in Europe.

Large-scale moss surveys have been carried out regularly (1980, 1985, 1990, 1995) in the Nordic Countries to provide information on time trends and spatial changes in atmospheric heavy metal deposition. These surveys have been gradually extended and more than 30 European countries participated in 1995. Moss surveys have several advantages over conventional deposition monitoring based on precipitation monitoring: The sampling is simple, which allows a large number of sites to be included in the survey, and the chemical analysis are much easier, due to higher concentration levels and strongly reduced contamination problems. Maps of the relative deposition of heavy metals in Europe have been produced as a part of these surveys.

In the present project, maps of the absolute deposition of heavy have been produced on basis of the moss surveys which make the results from the moss surveys much more useful for many research groups in Europe. Deposition maps based on moss surveys give a much higher resolution than those maps that can be constructed on the basis of the precipitation stations in Europe. Calibration factors for the transformation of relative values to absolute values have been developed by plotting concentrations in moss against wet deposition values for the same site determined from precipitation analysis. The precipitation data used in the project have been provided from the EMEP database.

At present discussions on emission control measures for heavy metals are being held in the framework of UN-ECE. Both measurements and modelling are used as a tool in this work. For heavy metals the lack of measurement stations in Europe makes it very difficult to test and verify models. Maps of heavy metal deposition in Europe on basis of high spatial resolution moss surveys are therefor be highly appreciated in several research areas in Europe.