Distribution, source apportionment, and health risk assessment of polycyclic aromatic hydrocarbons in urban soils from Shenyang, China

A total of 74 urban topsoil samples were collected from the central area of Shenyang, China. The concentration, distribution, source, and health risk of 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed. The 16 USEPA priority PAHs were detected in all soil samples. The total concentrations of PAHs ranged from 283 to 21,821 ng/g dry weight (dw), with a mean value of 2370 ng/g and median value of 1427 ng/g. The benzo[a]pyrene toxicity equivalent (BaPeq) concentrations ranged from 6.03 to 2403 ng/g dw, with a mean value of 308 ng/g and median value of 185 ng/g. High molecular weight PAHs were the predominant components. The spatial distribution revealed that soil PAH concentrations within the Two Ring Road were high, but low in the south of Hun River. Compared with other urban soils, the pollution of PAHs in urban soils of Shenyang was at a moderate level, but increased rapidly compared with previous years, especially fluoranthene. Diagnostic ratios of PAHs and positive matrix factorization model all suggested that PAHs in urban soils of Shenyang were dominantly from pyrogenic origins. The health risk assessment indicated that children had the highest total carcinogenic risk, followed by adolescents and adults. The differences between gender groups for the same age group were insignificant. Ingestion was the dominant exposure pathway, followed by dermal contact and inhalation. The total lifetime carcinogenic risks at all sampling sites were lower than the highest acceptable risk (10(-4)), and those of Eastern, Central, and Western Shenyang were higher than those of Northern and Southern Shenyang.