A fuzzy model of heavy metal loadings in Liverpool bay

We design a fuzzy model of the loadings of 10 heavy metals in Liverpool bay. Each metal concentration is associated with a fuzzy set contaminated, defined over the set of 70 sampling sites. The higher the concentration, the higher the degree of membership of the site. Six overall loading indices are calculated using aggregation connectives between fuzzy sets. The loading indices are then interpolated and plotted on a map. A visual inspection shows that: (1) product aggregation is most indicative for the locations of the disposal grounds; (2) mean aggregation reflects sediment movement in the bay well; and (3) maximum aggregation indicates all highly contaminated sites. The proposed fuzzy model is easy to implement and the results are directly interpretable. (C) 2000 Elsevier Science Ltd. All rights reserved.