Preliminary assessment of surface soil lead concentrations in Melbourne, Australia

Urban soils in many cities have been found to be contaminated with lead from past usage of leaded petrol, deteriorating lead-based exterior paints and industrial sources. Currently, the spatial distribution of soil lead concentrations in the Melbourne metropolitan area is unknown. The objective of this study was to perform a preliminary assessment of the spatial distributions of the surface soil lead (Pb) concentrations in the Melbourne metropolitan area, Australia. Fifty-eight surface soil samples were collected at a depth of 0-2 cm along three linear transects oriented across the Melbourne metropolitan area. Surface soil samples were also collected at a higher density in five Melbourne suburbs. Soil cores (0-50 cm) were collected in four locations, soil transects were collected at intervals with distance away from the roadway (0-50 m) in two inner city parks, and one control soil sample was collected in a rural setting. The median soil Pb concentration of the soil transect samples was 173 mg/kg (range 32-710 mg/kg), and the median soil Pb concentration of the five suburbs was 69 mg/kg (range 9-1750 mg/kg). The suburb of Footscray had the highest soil Pb concentration with a median soil Pb concentration of 192 mg/kg (range 40-1750 mg/kg). Soil Pb concentrations were generally higher nearest the centre of the Melbourne metropolitan area and in the west of Melbourne and lower in the outer suburbs to the east and north of the city centre. Soil Pb concentrations decreased with distance from roadways in the two transects taken from urban parks, and soil lead decreased with depth in the four soil cores. The soil Pb concentrations in the Melbourne metropolitan area appear to be lower than soil lead concentrations observed in inner city areas of Sydney New South Wales (NSW) and Newcastle NSW. The spatial extent of the soil Pb hazard remains undefined in portions of the Melbourne metropolitan area.