西藏色季拉山公路沿线PAHs分布、来源及风险

分别于2017年3月和12月沿色季拉山318国道采集表层土和冷杉（Abies Mill.）样品，测定了多环芳烃（PAHs）的含量.表层土和冷杉叶中∑₁₆PAHs的含量范围分别为30.21~366.94ng/g dw和39.53~236.42ng/g dw，组成以低环（2、3环）为主.通过特征单体比值法和主成分分析法分析表明，色季拉山PAHs主要来源于化石燃料和生物质的燃烧，同时也受到车辆石油泄漏和大气远距离传输的影响；通过反向气团轨迹判断，色季拉山PAHs大气传输污染主要来自于印度次大陆.色季拉山公路沿线土壤中PAHs的终生致癌风险值均低于1×10^-6，说明对当地居民的致癌风险较小.

Distribution,sources and risk of polycyclic aromatic hydrocarbons along the highway in Shergyla Mountain in Tibet

The surface soil and fir (Abies Mill.) samples were collected in March and December 2017 along the China National Highway 318 in Shergyla Mountain, respectively. The contents of polycyclic aromatic hydrocarbons (PAHs) in the samples were measured. The concentrations of ∑₁₆PAHs ranged from 30.21 to 366.94ng/g (dry weight) in the surface soil and 39.53 to 236.42ng/g (dry weight) in the fir leaves, respectively, and the lower rings (2- or 3-ring) constituents were dominants. The results of diagnostic ratios and principal component analysis suggested that the PAHs mainly originated from the combustion of fossil fuel and biomass, and also affected by oil leaks and atmospheric transmission. The atmospheric transmission pollution of PAHs could mainly result from the Indian subcontinent based on the backward air mass trajectories. The incremental lifetime cancer risks of PAHs in the soils along the highway in Shergyla Mountain were lower than 1×10⁶, indicating a lower carcinogenic risk to the local residents.