Soil contamination in community gardens of Philadelphia and Pittsburgh, Pennsylvania

Urban Farm DB summary

A 2023 study that sampled soils from 21 community gardens in Philadelphia city, the Philadelphia suburbs and Pittsburgh city, Pennsylvania, USA, in September–October 2021 and measured seven elements (Pb, Zn, Cu, V, Cd, Ni, As) by ICP-MS. City gardens had higher concentrations than suburban ones. All elements except vanadium fell below Pennsylvania Department of Environmental Protection guidelines, but against the stricter Canadian Council of Ministers of the Environment limit of 140 mg/kg for lead, 36% of Philadelphia city gardens, 60% of Pittsburgh gardens and 20% of Philadelphia suburban gardens exceeded it — so whether a garden counts as 'safe' or 'over the limit' depends on which standard is applied. In Philadelphia, concentrations generally fell with distance from historical smelter sites, though the correlation was significant only for zinc. Raised-bed soils were lower in lead and arsenic but often higher in zinc, copper, vanadium and nickel, which the authors attribute to ongoing deposition from road traffic and active industry rather than legacy contamination.