[Contents,Sources,and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Soils of Various Functional Zones in Yangzhou City, China].

The contents and sources of 15 US EPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in 59 surface soil samples (0-10 cm depth) collected from six functional zones, including cultural and educational area, park, residential area, vegetable garden, gas station, and industrial area, in Yangzhou City. The toxicity equivalent content of benzo[a]pyrene (TEQBaP) was adopted to assess PAH risks in soils. The results showed that the contents of Σ15PAHs in soil samples ranged from 21 to 36118 µg·kg-1, with a median value of 295 µg·kg-1. The composition of PAHs was dominated by 4-6 ring PAHs. The average contents of Σ15PAHs in various functional zones in Yangzhou City was in the order of industrial area > gas station > cultural and educational area > vegetable garden > residential area > park. Correlation analysis showed that the contents of Σ15PAHs were significantly positively correlated with the contents of both TOC (P<0.05) and BC (P<0.01) in soil samples from whole Yangzhou City. However, the contents of Σ15PAHs had no significant correlations with the contents of both TOC and BC in soil samples within each functional zone except gas station, in which the contents of Σ15PAHs had a significant correlation with those of BC (P<0.01). The results of PAH ratios showed that the sources of PAHs in soils of various functional zones were mainly from oil leakage and the combustion of oil, coal, and biomass, although there were some differences among them. The values of ΣTEQBaP of 15 PAHs ranged from 2 to 4448 µg·kg-1 in the soil samples of Yangzhou City. According to the standard value of 33 µg·kg-1 of ΣTEQBaP for 10 PAHs in the soil environmental standard of Netherland, 45.8% of soil samples exceeded the standard in Yangzhou City. The percentages of soil samples exceeding the standard of various functional zones in Yangzhou City were in the order of industrial area (70%) > gas station (60%) > cultural and educational area (55.6%) > vegetable garden (50.0%) > residential area (30%) > park (10%). Hence, in all the functional zones of Yangzhou City, there were some soil samples with potential ecological risks, which was relatively higher in industrial area and gas station, and relatively lower in residential area and park.

[Concentrations, sources and ecological risks of polycyclic aromatic hydrocarbons in the topsoils of Quanzhou City, China].

The concentrations of 15 US EPA priority polycyclic aromatic hydrocarbons (PAHs) in 33 soil samples (0-10 cm layer) collected from various functional zones in Quanzhou city were analyzed by UPLC coupled with fluorescence detector. The sources of PAHs in the topsoils were apportioned using isomer ratios, and factor analysis and multiple linear regression. The ecological risks of PAHs in the topsoils were evaluated by using benzo[a]pyrene toxic equivalents (TEQ(BaP)). Results showed that the total concentrations of PAHs in the soils ranged from 28.2 to 1432.3 microg x kg(-1), and 4 to 6 ring PAHs were the dominant compounds. The total concentrations of PAHs in soil samples from different functional zones decreased in the order of industrial areas > residential areas > scenic areas > agricultural fields. The PAHs in soils of Quanzhou city mainly originated from the combustion of coal, biomass fuels (straw), and liquid fossil fuels including gasoline and diesel. The TEQ(BaP) of the 15 PAHs ranged from 1.6 to 131.6 microg x kg(-1), with an average value of 38.9 microg x kg(-1). The total TEQ(BaP) of 10 PAHs in 34.6% of the soil samples exceeded the Dutch target reference value, suggesting that there are potential ecological risks in the topsoils in some areas of Quanzhou city.

[Sorption and desorption of phenanthrene by organo-mineral complexes with different bridge cations].

Sorption and desorption of phenanthrene by organo-mineral complexes with Ca2+, Fe3+ and Al3+ as bridge cations were studied according to the association type between organic matter and minerals in natural soils. The results showed that the data of phenanthrene sorption and desorption by different cation saturated montmorillonite and their corresponding humic acid and mineral complexes could be fitted with Freundlich model, and the order of the sorption capacities (Kf) were Ca-Mont (0.184) > Fe-Mont (0.028) > Al-Mont (0.015) and Fe-Mont-HA (2.341) > Ca-Mont-HA (1.557) > Al-Mont-HA (1.136), respectively. The Kf values of humic acid and mineral complexes were far greater than those of minerals, which demonstrated that humic acid made great contributions to the sorption of phenanthrene in the organo-mineral complexes. However, the Kf values of the organo-mineral complexes with different bridge cations were not consistent with their organic carbon content, which indicated that both the organic carbon content and the combined types between organic matter and mineral could affect the sorption capacity of phenanthrene by the organo-mineral complexes. The desorption hysteresis of phenanthrene was significant for Ca2+ and Al3+ bridged organo-mineral complexes. Desorption hysteresis of phenanthrene was mainly from the sorption of phenanthrene by organic matter, and the contributions of mineral to the desorption hysteresis were not significant.