MAPPING HEAVY-METALS IN POLLUTED SOIL BY DISJUNCTIVE KRIGING

The soil of some 50 km(2) around the town of Weinfelden in north-east Switzerland has been sampled and analysed to estimate and map the conc entrations of heavy metals before an incinerator for the canton's wast e is built. Given that the estimates are subject to error, the probabi lities that true values exceed the maximum tolerable concentrations of the Swiss federal guide have also been estimated by disjunctive krigi ng. These may now be used by the local planners for making decisions. Of the metals examined, lead exceeded the guide value at several sampl ing points, and a moderate probability of excess of lead is fairly wid espread. Copper exceeded the guide value in vineyards and orchards, bu t also in a few places elsewhere, and the estimated probabilities of e xcess were not negligible. The other two metals of concern, cadmium (w ith one exception) and zinc, had concentrations much less than the gui de values. The patterns of distribution of the four metals were simila r, the product-moment correlations among them are substantial, except in the vineyards and orchards, and it seems likely that they had commo n sources. (C) 1997 Elsevier Science Ltd.