岩溶地下河流域表层土壤多环芳烃污染特征及来源分析

采集重庆南山老龙洞地下河流域农田土壤(0～20 cm),利用气相色谱-质谱联用仪(GC/MC)测定了土壤样品中16种优控多环芳烃(polycyclic aromatic hydrocarbons,PAHs)含量,分析其含量和组成,污染水平及污染来源.结果表明,流域内不同地点表层土壤16种PAHs总量变化范围为277～3301 ng·g-1,平均值为752.6 ng·g-1±635.5 ng·g-1,所有样品均遭受污染,其中57%为轻污染,29%为污染土壤,而14%为重污染.多环芳烃的组成以2～3环为主,占总量的28.72%～72.68%,平均值为48.20%;4环和5～6环含量分别为7.77%和34.03%.土壤PAHs含量与有机质(SOM)含量显著相关,而与pH值相关性不强.比值法和主成分分析(PCA)表明,流域内土壤主要来自交通排放与煤炭、石油及生物质燃烧的混合源以及石油源.

Source and Contamination of Polycyclic Aromatic Hydrocarbons in Surface Soil in Karst Underground River Basin

Surface soil (0-20 cm) from various agricultural sites in Laolongdong underground river basin was collected to determine the concentrations, compositional profiles, and sources of 16 priority polycyclic aromatic hydrocarbons (PAHs). PAHs were measured by GC/MC. The total concentrations of PAH16 ranged from 277-3301 ng·g^-1, with a mean of 752.6 ng·g^-1±635.5 ng·g^-1, and 57%, 29% and 14% of soil samples were slightly, moderately and heavily polluted by PAHs, respectively. The PAH compositional profiles were dominated by 2,3 ring compounds, which accounted for 28.72%-72.68%(a mean of 48.20%) of the total PAHs, while 4 ring and 5,6 ring PAHs accounted for an average of 7.77% and 34.03%, respectively. Soil organic matter(SOM) was found to be significantly correlated with the 16 PAHs and total PAHs. However, pH value was slightly correlated with the 16 PAHs and total PAHs. Isomer pair ratios and Principal component analysis (PCA) suggested vehicles, coal, petroleum and biomass combustion as the main sources of PAHs, and another major source was petroleum.