A citywide analysis of urban soil in parks: metals and organic matter concentration and homogeneous infiltration capacity

Urban soil parks have been extensively studied, but there is still no consensus on how urban soils properties change both spatially and at different urbanization levels. There is evidence that anthropogenic pressures such as the level of urbanization can affect the physical and chemical properties of urban soils, but the conclusions change depending on the city studied. This paper evaluates how topsoil properties differ as a function of urbanization level (parks located inner or outer the main city ring-road) and park characteristics (type of park i.e. treed or turf-covered). The following soil properties were measured in 59 urban topsoils: organic matter (OM), copper (Cu), lead (Pb), and zinc (Zn).  Near-saturated hydraulic conductivity (K_near) was measured in two urban parks. Comparison of urban soils located inside and outside the main city ring showed a significant increase in the amount of OM (p < 0.05). Based on a soil survey from the 1990s, the increase in OM was confirmed by comparison with background values. Higher values of Cu, Pb and Zn (p < 0.05) inner the ring was found in comparison to outer. K_near ranged from 0.192 mm/hour to 150.0 mm/hour, near to the lower bound values reported in other similar urban soil studies. No statistically significant differences between parks were found (treed vs. turf-covered). OM and metals show higher values in more urbanized areas, showing the potential effect of anthropogenic pressure on urban soils, while K_near did not vary regards to different parks, showing a lower infiltration capacity than in other studies.