Legacy contamination in Chicago urban park soils: Spatial patterns, socioeconomic disparities, and implications for urban agriculture

Urban parks are increasingly used for recreation and urban agriculture, yet their soils may retain legacy contamination. This study quantified seven trace elements in topsoils of five Chicago parks ( n = 233) using portable X-ray fluorescence. Pb, As, Cu, Zn, and Cr exceeded Illinois background levels in 89%–100% of samples; As and Pb exceeded EPA screening levels in 94% and 7%. Higher contamination was observed at parks farther from the city center: Douglass and Humboldt parks, in predominantly minority, lower income neighborhoods, versus Cottontail, Grant, and Webster. Principal-component analysis (PCA) confirmed an anthropogenic signature (PC1, 51.7%) driven by Pb, Zn, Cu, and As and a geogenic signature (PC2, 17.0%) associated with Mn and Ni. Areas in Douglass and Humboldt parks were classified as not safe for gardening in native soil; Webster as safe with minor restrictions. Park soil contamination follows socioeconomic gradients, reflecting environmental injustice and the need for targeted remediation.