Polycyclic aromatic hydrocarbons (PAHs) are highly teratogenic, persistent carcinogens, and ubiquitous environmental pollutants. To determine the impact of rapid urbanization on sediment/soil PAHs, we collected 30 cm soil cores in ditch wetlands, riverine wetlands, and agricultural lands along the lower reaches of the Shiwuli River feeding Chaohu Lake, China. Ecological risk effects were evaluated by two models based upon Benzo[a]pyrene toxic equivalency (TEQ-BaP) and total toxic units (TUs). The presence of PAHs, such as BbF, BkF, InP, and BgP, that are known pollutants of concern, suggests certain ecological risks. The concentration of PAHs in the surface layer followed in the order of: ditch wetlands (617.2 ng/g average), riverine wetlands (282.1 ng/g average), agricultural lands (103.7 ng/g average). PAHs in ditch sediments were vertically distributed evenly, and PAHs in agricultural soils were concentrated in the surface soil. In riverine wetland sediments, the 2-, 3-, and 4-ring PAHs had a uniform distribution, whereas the 5- and 6-ring PAHs were concentrated in the surface soil. Redundancy analysis (RDA) explored the correlation between the environmental properties and the occurrence of PAHs. Total organic carbon (p = 0.010), percent clay (p = 0.020), and distance (p = 0.020) were the primary factors in ditch wetlands. Depth (p = 0.010) and distance (p = 0.006) were the main factors in agricultural lands. There were no significant correlations in riverine wetlands. The correlation between the distance from the built-up urban areas and pollutant concentration showed that the closer the distance, the greater the concentration of PAHs.

No abstract

PAHs (Polycyclic Aromatic Hydrocarbons) increases the potential harm to ecosystem and human health.The fungi is considered as a powerful choice for degradation of PAHs. The researches on the effect of PAHs on fungal population in sediment/soil mostly stayed in the laboratory simulation that based on extreme pollution. This study investigated the fungal population of the urban wetland by high-throughput sequencing in situ micro-pollution state. Our statistical analysis revealed signi cant difference in the whole fungal population at the phylum among the three land use types. Among them, Ascomycota was the dominant fungi at the phyla in three land use types. Fungal genus of degrading PAHs were signi cantly correlated with Dibenz[a, h]anthracene (P = 0.018) in ditch wetland, Total Organic Carbon (P = 0.02) and Fluoranthene (P = 0.04) in riverine wetland, and Electrical Conductivity (P = 0.018) in agricultural land. PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) suggested that 20 enzymes were present related to PAHs metabolism in three land use types.Speci cally, monoxygenase, dehydrogenase, and laccase were most abundant among inferred enzymes, indicating that the urban wetland had potential for the degradation of PAHs. This study contributed to indepth understanding of the structure and function of fungal population and provided a theoretical basis for PAHs microbial remediation in the in-situ environment.