[Characterization of polycyclic aromatic hydrocarbons contaminations in surface sediments from Zhalong wetland,...

Soxhlet extraction, silica gel alumina column for separation and clean up and gas chromatography-mass spectrometer (GC-MS) for qualitative and quantitative analysis were used for study environmental behavior of 15 priority PAHs of twelve surface sediment samples collected from Zhalong wetland, Heilongjiang Province. The objectives of this study were to identify the PAHs contamination level, composition pattern, pollution sources and pathways, and to assess the ecological risk of PAHs to aquatic life in Zhalong wetland. The total concentrations of 15 priority PAHs ranged form 31.9 to 290 ng/g (dry weight), with a mean value of 130 ng/g. The PAHs profiles were dominated by two-to four-ring compounds which accounted for 90% of total PAHs. Phenanthrene, fluorine, fluoranthene, and pyrene represented the highest fractions in all surface sediment samples. Comparing with other results from wetlands and lakes in China or other countries, the PAH concentrations level in Zhalong wetland surface sediments were relatively low, in the same range of Lharu wetland. The linear regression analysis showed that the concentrations of PAHs were significantly correlated to the sediment total organic carbon (TOC) content (R2 = 0.87). PAHs contamination might mainly came from biomass and coal combustion. After long range atmospheric transport and deposition, the released PAHs finally accumulated into wetland sediment. Ecology risk assessment indicated that phenanthrene and fluorine had exhibited a tendency of accumulation on surface sediment of Zhalong wetland, which would exert negative toxic effect on aquatic organism.