Accumulation Of Polycyclic Aromatic Hydrocarbons (PAHs) In Permafrost At High Latitudes

In this paper,16 PAHs in the soil of permafrost regions in Daxinganling,China were studied.It discusses the content,composition and vertical distribution of PAHs in soil.The correlation analysis between TOC content and?PAHs concentration,?PAHs and monomer PAHs,16 PAHs monomer were analyzed.And source analysis of PAHs has also been studied.The following conclusions have been drawn:the concentration of PAHs in the soil of permafrost regions in the Greater Khingan Mountains in China ranges from 76.96 to 1637.47 ng·g^-1?dry wt.?,the average is 538.72 ng·g^-1?dry wt.?.The contents of Anth,Chry,and BaA in the 16 PAHs were relatively high.The PAHs in the soil mainly consisted of 3-ring and 4-ring PAHs,and the PAHs in the 2-ring and6-ring were lower.The vertical distribution pattern of PAHs in soils in permafrost regions shows that the concentration of?PAHs and PAHs in different rings showed a downward trend as the soil depth deepened.However,high molecular weight PAHs concentration decreased more sharply than the lower ring PAHs,the results showed that the adsorption of high molecular weight PAHs on soil was stronger in soil,and the migration ability and permeability of high molecular weight PAHs were less than that of lower ring PAHs under leaching.The?PAHs and PAHs in different rings in each soil layer varied greatly from 0 to 90 cm,and the concentration of PAHs below 90 cm decreased gradually,indicating that the frozen soil can effectively retain PAHs and prevent PAHs from polluting groundwater and deep soil,and it plays the role of low permeability barrier.The first peak of PAHs concentration appears in the surface or subsurface layer of the soil is related to the richness of organic matter in this layer,and the second peak of PAHs concentration appears in the thaw layer is related to the retention effect of permafrost on PAHs.The vertical distribution of PAHs in forest and wetland soils is consistent with the vertical distribution of PAHs in the soil of the entire permafrost region.In the soil of farmland,the concentration of?PAHs and the concentration of each PAHs monomer in the soil did not change significantly in the vertical direction.In this study,200 cm deep soil was divided into 6 layers by cluster analysis,and the cumulative levels of low-ring PAHs such as 2³ rings were 0²0cm>30⁵0 cm>80⁹0 cm>20³0 cm>50⁸0 cm>90²00 cm;the cumulative levels of high-ring PAHs in 4⁶ rings are 30⁵0 cm>0²0 cm>20³0 cm>80⁹0 cm>50⁸0cm>90²00 cm.There was a correlation between the concentration of?PAHs in soil and the TOC content;The linear correlation between?PAHs and Benzo[a]anthracene,Chrysene,Fluoranthene,Pyrene,Benzo[a]pyrene and Dibenzo[a,h]anthracene were the best.Therefore,these six kinds of monomers can be regarded as the main representative of PAHs in the soil of permafrost regions in Greater Khingan Mountains in China,so as to simplify the task of PAHs monitoring in soils in permafrost regions in China.PAHs with the same source will be more relevant.Using the ratio method and principal component analysis?PCA?method to analyze the source of PAHs in soil,it was found that PAHs in high latitudes permafrost soils in China mainly come from high temperature combustion sources and petroleum pollution sources,and a small amount of external sources of atmospheric long-distance transmission.This dissertation has important scientific significance for the analysis of PAHs migration and transformation rules and environmental fate;its research results are not only conducive to a deep understanding of the migration and transformation of pollutants at the national scale and environmental fate,but also for China's response to climate change and formulate relevant environmental pollution control policies provide scientific evidence to reduce the adverse effects of persistent organic pollutants on humans,animals and plants,and the ecological environment.