Innovative isotopic modeling and risk assessment of PTEs and PAHs in urban soils

This study investigates the health and environmental risks associated with Potentially Toxic Elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) in urban soils of Sanandaj City, Iran, using an innovative isotopic modeling approach. A total of 53 surface soil samples were systematically collected, revealing elevated concentrations of Zinc (Zn), Copper (Cu), Nickel (Ni), Cadmium (Cd), Chromium (Cr), Arsenic (As), and Lead (Pb), with Cd posing a significant ecological risk. Ecological risk assessments indicated low risk for most elements, except for Cd, which showed a notable environmental threat. Non-carcinogenic risk assessments, based on ingestion, inhalation, and dermal exposure, revealed no significant risks for both children and adults, although children exhibited higher risks, particularly in ingestion. However, carcinogenic risk assessments demonstrated that metals like Cr, Ni, Pb, Cd, and As exceeded the acceptable risk thresholds for both populations, highlighting a severe health concern. PAH concentrations ranged from 126.44 to 2460.87 µg/kg, with a dominance of high molecular weight PAHs, suggesting significant pyrogenic sources. A novel isotopic modeling method, based on ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb ratios, effectively traced lead contamination sources, identifying industrial emissions and vehicular exhaust as the primary contributors. This study offers valuable insights into urban soil contamination and provides a robust framework for environmental management and policy-making to mitigate risks from PTEs and PAHs.