[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 277-3 301 ng x g(-1), with a mean of 752.6 ng x g(-1) +/- 635.5 ng x 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.