Assessment of potentially toxic elements in the soils of Moscow playgrounds: pollution sources and human health risks

Playgrounds serve as the primary play areas in metropolitan areas for children - a demographic that is particularly vulnerable to environmental contaminants. Accumulation levels, spatial distribution, sources, and potential health risks to children of Potentially Toxic Elements (PTEs) in soils from 97 Moscow playgrounds were studied. Concentrations of 17 PTEs (Be, V, Cr, Co, Ni, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Ba, W, Pb, Bi) in bulk soil samples and PM₁/PM₁₀ fractions were determined using ICP-MS and ICP-AES. Most PTEs exceeded regional background levels. Compared to bulk samples, PTE concentrations in PM₁₀ were  increased by factors of 1.3 - 6.0. Highest accumulation of Sb, Pb, Zn, Cu, As, Cd occurred near industrial zones. Analysis of PM₁ in the most contaminated soil samples revealed further enrichment with PTEs, particularly in enclosed courtyards. Positive Matrix Factorization identified five main sources: lithogenic (32.6%), construction and demolition debris (22.0%), traffic emissions (16.5%), machinery and metalworking (14.1%), and multi-facility industrial sources (14.6%). The non-carcinogenic hazard index (HI) for children was generally low (mean HI = 0.75), reaching moderate levels (HI = 1.0 - 10) in 13% of samples. The total carcinogenic risk (TCR) was at a moderate level (mean TCR = 6.1 × 10^-5); 8% of samples near major highways and redeveloped industrial zones exceeded TCR = 1 × 10^-4. Arsenic (As), mainly from construction and demolition sources, contributed 90% of the total TCR. This study provides critical evidence for urban planners and public health officials, highlighting the necessity of revising playground placement regulations and implementing targeted pollution control measures, especially during the redevelopment of industrial areas, to mitigate children's health risks.