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[Variation Characteristics and Sources of Polycyclic Aromatic Hydrocarbons in Karst Subterranean River During Rainfall Events].

The water samples were continuously collected at the outlet of Nanshan Laolongdong subterranean river basin, which is located in Chongqing, during the rainfall event in June 2014. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) in water were quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS). The objectives of this study were to reveal the variation characteristics and sources of PAH16 in karst subterranean river during the rainfall event. The results showed that the subterranean river responded promptly to the rainfall, and there were four peaks of the total concentrations of PAH16, two peaks occurred during the flow rise stage, the others were in the maximum flow and flow decline stages. The total concentrations of PAH16 ranged 101-3 624 ng x L(-1), with a mean of 578 ng x L(-1), the total concentrations of 7 carcinogenic PAHs ranged ND-336 ng x L(-1), with a mean of 31.1 ng x L(-1). The PAH compositional profiles were dominated by 2,3-ring compounds, which accounted for 86.17% of the total concentrations of PAH16. The total concentrations of PAH16 were most influenced by the rainfall, through the cleaning of atmospheric pollutants by the rain and the scouring of the surface contaminants by the rainfall runoff. The PAHs in water mainly originated from the incomplete combustion of petroleum products and fossil fuels such as coal, as well as natural digenetic process. Compared to other areas in the world, the concentrations of PAH16 were generally at moderately polluted and heavily polluted levels.