Assessing heavy metal pollution in urban children's playgrounds: Comparative analysis of soil, dust, and moss bioaccumulation

Abstract

Toxic heavy metals are ubiquitous environmental contaminants that can detrimentally influence human well-being, especially in the pediatric population. This study investigated soil, dust, and moss contamination collected from six urban children's playground (parks 1 to 6) in Çankaya District with heavy metals (Cr, Cu, Cd, Ni, Pb, and Zn). The highest values of Cu (44.1 mg/kg), Ni (45.6 mg/kg), and Pb (44.2 mg/kg) were recorded from park dust. Moss samples showed higher values of Cr and Zn, respectively, as 68.7 mg/kg and 284.3 mg/kg. Of these, surface soil presented the lowest concentrations, with Zn showing the highest concentration at 259 mg/kg and Cd the lowest at 1.9 mg/kg. Moss showed the highest total metal load Σ=482.1 mg/kg, followed by dust Σ = 457.9 mg/kg and soil Σ =3 88.3 mg/kg. Significant differences of p < 0.05 between the soil and other sample types, together with a strong correlation of R2 = 0.9443, may indicate that moss metal concentration is influenced by natural and anthropogenic sources by wet or dry deposition. Spatial analysis revealed metal hotspots near roadways, with Cr and Cu less concentrated in traffic areas. Significant variability was noted across parks, far from vehicular traffic and polluting land uses (parks 1 and 2), showing lower concentrations. Principal component analysis (PCA) and positive matrix factorization (PMF) identified four emission sources: diesel combustion, transportation, and fossil fuel combustion, which are transported up to several kilometers away from their sources and transferred to the soil by atmospheric deposition. Enrichment and bioaccumulation factors highlighted high Cd enrichment in dust, with significant bioaccumulation in mosses. Pollution index values varied, with parks under the pressure of vehicular traffic, commercial and industrial zones (park 6) showing the highest contamination. These local findings draw attention to the striking impact of land use decisions at a lower scale on the health risks of humans, especially children.