Assessment of Pollution, Sources, and Risks of Polycyclic Aromatic Hydrocarbons in Soil from Urban Parks in Xi'an City, China

Abstract

A total of seventeen surface soil samples were collected from urban parks in Xi'an city. The concentration of sixteen priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by high performance liquid chromatography (HPLC). In addition, the composition, source, pollution level and a risk assessment of PAHs in surface soil of park were evaluated. The results showed that the total concentrations of sixteen PAHs ranged from 0.362 to 1.336 μg·g-1, with a mean value of 0.591 μg·g-1. The concentration of seven carcinogenic PAHs (Σ7CPAHs) ranged from 0.051 to 0.528 μg·g-1, with a mean value of 0.181 μg·g-1. Compared to the ΣPAHs levels of other cities of China, the ΣPAHs in park surface soils in Xi'an are relatively low. PAHs in the soil samples were dominated by low molecular weight PAHs with 2 and 3 rings. The results of source analysis showed that the PAHs in park surface soil mainly originated from the combustion of fossil fuels, however, the source of PAHs in some samples is complex and from mixed sources, such as oil spills, oil burning, and incomplete combustion of coal and biomass. The ecological risks of PAHs in the surface soil were evaluated according to the soil quality guidelines to be ERL (effects range low) and ERM (effects range median), and these results showed that all samples, in general, were polluted. However, the potential ecological risks of PAHs were at a low level. The incremental life cancer risk (ILCR) assessment indicated that health risks for children and adults were both in a permissible range, however, the risks for children exposed to the soil were considerably higher than for adults. Dermal contact was the main exposure pathway that resulted in the relatively higher risk, followed by ingestion.