Geochemistry of urban surface soils — Monitoring in Trondheim, Norway

The objective of this study was to assess the spatial extent of heavy metal pollution in the urban part of Trondheim City and to assess the temporal variation over a period of ten years (1994–2004) by making comparisons to a previous survey. 321 surface soil samples were analysed, whereof eight of the analysed elements; arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) are presented in this study. Statistical tests show that all elements, except lead, have decreased in concentration statistically significantly over ten years. Three important pollution sources have been closed down at the end of the 1990s, the hospital waste incinerator, one of the crematories and a metal smelter. No correlation between element concentration and organic matter could be found. A principal component analysis (PCA) performed on the results also indicates that Cd, Zn, Pb and Hg correlate with anthropogenic input.