Metal content of surface soils in parks and allotments from three European cities: initial pilot study results

A pilot study of metal content and basic soil properties was undertaken in a number of parks and allotments in the cities of Glasgow, UK, Torino, Italy, and Sevilla, Spain. Between 40 and 60 samples were collected from each city, with soil from two depths. The maximum metal contents (aqua regia) found were 698 mg/kg Cu; 1004 mg/kg Zn; 300 mg/kg Ni; 356 mg/kg Cr and 7051 mg/kg Pb. Variability of metal content showed similar patterns across all cities, with a number of outlier data points. Surface and subsurface samples were comparable within sites. Cu, Zn and Pb levels appeared to contain most variability and extreme data points, while Ni and Cr were more homogeneous. The data support previously published observations of anthropogenic association (Cu, Zn and Pb) and natural sources (Ni and Cr), found in urban environments influenced by diffuse pollution. Within the Glasgow data, differences in the variability of metal content in park and allotment soil are not dramatic, but do reflect the influence of different agronomic activities. The study has provided baseline information for ongoing pan-European urban soil research funded through the EU.