Conclusions

Even though production emissions in Sweden have decreased during the last few decades, the accumulation of lead and chromium in soils and sediments will continue owing to the dissipative consumption losses of various products. To give an example: Suppose consumption emissions remain on the 19701980 level while production emissions are assumed to be low or even negligible; then the calculated amounts of chromium in the soils of some urban areas (e.g. Stockholm) will be as high as they are in the most polluted industrial regions today within only a few decades (Bergbäck et al., 1989). Thus, urban environments can be regarded as ecological "hot spots" for toxic metals. Also, in the future agricultural soils in suburbanized areas may be close to exceeding their carrying capacity for trace metal pollution.

Fig. 4 Chromium and lead emissions in Sweden compared with supply (imports-export + production) in thousands of tonnes per year

The changing spatial pattern of heavy metal loads in Sweden reflects the dynamics of industrialization. The first industrial revolution was based on local resources, such as raw materials and energy sources. Later, with greater affluence and mobility, an "urban world" developed. Consequently, the pollution load in soils and sediments has altered from being a "defined pollution problem" within certain industrial regions to a situation where the end-use of products, together with the mobility pattern of goods, define the pollution problem.

Fig. 5 The ratio between total emissions and weathering for lead, chromium, and cadmium in Sweden

In a general sense, our results illustrate a new dimension of the landscape. Industrial and urban areas often have soils and sediments with a higher recognized level of heavy metals. In these areas the "societal weathering rate" exceeds the natural one. In rural areas, with a more natural background dominated by the average bedrock composition, the pollution load of heavy metals is still less pronounced. The consequences of this development are difficult to predict, but it is obvious that a new dimension will be added to the conceptualization of the landscape, with particular implications for land-use planning.