Multimedia mapping in urban areas

One of the challenges of geochemical mapping is to provide society with reliable data on background levels in the environment. Such background levels are essential in order to understand the degree of pollution and in order to set sensible remediation target values. In Sweden, an urban geochemical mapping programme was initiated 1998. Today, four cities have been covered using a multimedia sampling programme consisting of soils (top and sub), transplants of water moss (Fontinalis Antipyretica ), and stairstep moss ( Hylocomium splendens).
The primary target of the urban geochemistry programme is to determine background levels of up to 45 different elements (depending on sampling media), e g Ag, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, La, Li, Mg, Mn, Mo, Ni, P, Sb, Se, Sn, Ta, Th, Ti, Tl, U, V, W, Y, and Zn. An evaluation of the results, using a range of statistical methods, shows that for most samples, the levels are not significantly affected by anthropogenic activities in the form of point sources. For some elements, especially in certain soils, natural levels are sometimes or often high compared with target values set by the Swedish Environmental Protection Agency. It is therefore suggested that using data from geochemical mapping projects in urban areas is important in order to avoid erroneous and perhaps costly decisions by decision-makers.
Examples of results from the four cities (Stockholm, Västerås, Gothenburg, and Uppsala) will be presented.