MAPPING STOCK AT RISK AND RELEASE OF ZINC AND COPPER IN SWITZERLAND - DOSE RESPONSE FUNCTIONS FOR RUNOFF RATES DERIVED FROM CORROSION RATE DATA

摘要

Copper and zinc are the most abundant facade and roofing materials sensitive for corrosion in Switzerland. For calculating potential material losses of copper and zinc by corrosion-induced runoff, i.e. washed or blown away material, dose-response functions (DRFs) are derived from the results of a Swiss outdoor corrosion exposure programme (Leuenberger-Minger et al, 2002b, Mater. Corros. 53, 157-164). The DRFs are also compared with other DRFs available from literature. Based on these DRFs, calculated runoff rates of Cu and Zn are mapped for Switzerland on a 250 x 250 m raster. The required input maps (climate and pollution levels) are produced by spatial interpolation of monitoring data from over 60 stations. The stock at risk of zinc and copper which are exposed in open atmosphere is calculated by two methods: (1) The bottom-up method uses data which were evaluated in a representative region in Switzerland by estimating the installed metallic roof and facade materials in the field. These data are projected to the total area of Switzerland on the basis of a land-use map. (2) The top-down method uses statistical data of imported zinc and copper material. The amount and surface of material that is used under outdoor conditions are calculated by use of different assumptions. The maps of runoff rates and stock at risk are then overlaid for calculating the annual flux of released metals. While the economic aspect of corrosion is presumably less important, the ecological risk of the runoff of metals should be considered in future research and mapping activities.