Fifty-five soil samples were collected across the central and eastern Qinghai-Tibetan Plateau during July to August in 2013. These were analyzed for the sixteen polycyclic aromatic hydrocarbons (PAHs) called out by the USA EPA. The concentration characteristics, sources, and potential ecological risk assessment of the sixteen PAHs in the soils were investigated. The soils were extracted by ultrasonic extraction, purified by an HLB solid-phase extraction column, and quantified by gas chromatography-mass spectrometry (GC-MS). The total PAH concentrations ranged from 40.47 to 1276.40 μg·kg-1, with a mean of 267.97 μg·kg-1. Low-ring PAHs (two and three rings PAHs) were dominant in all samples, and the proportion of phenanthrene was the highest. The sources of PAHs were assessed by diagnostic ratios and a principal component analysis (PCA), which indicated that the main sources of the PAHs originated from petroleum and biomass combustion. The toxic equivalent concentration (TEQ) concentration of benzopyrene-(a)-pyrene (TEQBaP) in soils ranged from 3.73 to 79.32 μg·kg-1, with an average concentration of 12.84 μg·kg-1. The TEQBaP in 4% of the soil samplings exceeded the Dutch target reference value (33.00 μg·kg-1), suggesting that a small portion of the soils in the Qinghai-Tibetan Plateau have potential ecological risk.
Keywords: Qinghai-Tibetan Plateau; ecological risk assessment; polycyclic aromatic hydrocarbons; soil; source.