Urban soil geochemistry of two Nordic towns: Hämeenlinna and Karlstad

Urban soil geochemical mapping was carried out using the same sampling and analytical protocols in two Nordic towns: Hämeenlinna in Finland and Karlstad in Sweden. Aqua regia extractable concentrations of 53 elements determined in urban topsoil (0-10 cm) were compared statistically, including cluster and factor analysis, and spatially for selected elements (As, Au, Hg, Ni and Pb). Soil parent material and land use were re-classified before comparison to give a standardised classification for the two towns. Four land use classifications are used: sensitive land, industrial, green areas, and parks. Concentrations of potentially hazardous elements are often elevated in clay and fine-grained human-made soil. Comparison of land-use types revealed that the median concentration of almost all studied elements was highest in industrial areas.