| Polycyclic aromatic hydrocarbons are a class of persistent organic pollutants withteratogenic, carcinogenic and mutagenic effects, which are common in environmentalmedia, such as soil, air and water.Since this century, various environmental pollutionproblems caused by PAHs attract scholars all over the world to pay attention andexplore. In recent years, the study on PAHs in soil and atmosphere contributed by thedevelopment of petrochemical industry has gradually became a hot topic in this field.The concentrations of16US EPA PAHs in topsoil and atmospheric deposition aroundtypical petrochemical industrial zone were detected by High Performance LiquidChromatography.The concentrations,compositions and distributions in topsoil andatmospheric deposition were analyzed, the main factors that affected the changes ofcomposition and distribution were discussed, PAHs in soil and atmospheric depositionwere cooperatively analyzed, the contribution of atmospheric deposition of PAHs totopsoil was estimated,the diagnostic ratios and principal component analysis were usedto analyse the source of PAHs,the main results are as follows:(1)The concentrations of total PAHs in topsoil around the petrochemical industryregion ranged from842.8to5160.9μg/kg, and the average concentration was2095μg/kg, the carcinogenic PAHs accounted for52.8%,compared with averageconcentration of total PAHs in topsoil of other related research areas in domestic andforeign, the PAHs pollution level of topsoil are severe.In all samples,4~6ring PAHswere the major components,4ring and5~6ring PAHs average accounted for39.2%and31.9%,2~3ring PAHs average accounted for28.3%.The concentrations of totalPAHs in topsoil with increasing distance from the main source of pollution showed adecline trend, which also influenced by local emissions. (2)PAHs mainly concentrated in the topsoil around the petrochemical industryregion,the average concentrations of PAHs in0~20cm,20~40cm and40~60cm soilwere2095μg/kg、1143.9μg/kg and591.7μg/kg, respectively. There was a positivecorrelation between total PAHs and TOC, related coefficient was between0.90and0.95(P <0.01).With the increasing of soil depth, the content of PAHs and TOC emerged asa significant downward trend, the proportions of4~6ring PAHs decreased, while theproportions of2~3ring PAHs increased, The vertical migration ability of4~6ringPAHs was weaker than2~3ring PAHs, TOC could be a main factor that affected verticalmigration of PAHs in soil.(3) The average deposition fluxes of PAHs in atmospheric deposition from thesurrounding industrial areas and residential areas were4441.3and3388.5ng/(m2·d)respectively.The average concentrations of total PAHs were7984.9and6944.6ng/g,respectively,the average atmospheric dust fluxes were0.55and0.39g/(m2·d),respectively.Compared with other domestic and foreign research results, thepollution level of the total PAHs deposition fluxes from the surrounding industrial areaswas at a medium level. PAHs deposition fluxes showing a decreased trend from westto east in the study area.The sort of PAHs composition in atmospheric deposition was3~4ring PAHs＞5~6ring PAHs＞2ring PAHs.(4)The dust deposition fluxes and PAHs deposition fluxes of each sites in the studyarea presented positive linear correlation, the related coefficients of two areas were0.89and0.91(P<0.01), respectively. PAHs deposition flux and dust deposition flux ratiosof surrounding industrial areas were significantly higher than residential areas.It wascaused by the prevailing wind direction (east) and wind speed (2-3grade) of thismonth,which is not conducive to long distance transport of pollutants. To some extent,the combined action of pollution emission characteristics, rainfall, wind direction andwind speed et al had an effect on PAHs deposition fluxes.(5) The accumulation of PAHs in soil is a long and slow process, which has nosignificant correlation with short-term atmospheric deposition (P>0.05). The PAHs oftopsoil mainly consisted of4ring PAHs, and the atmospheric deposition mainly wascomposed of3ring PAHs, atmospheric deposition to a certain extent had a considerablecontribution to the accumulation of PAHs surrounding the industrial area, annualconcentration is increased by2.91~5.89μg/kg.(6) According to the diagnostic ratios and principal component analysis, the sourceof PAHs in the topsoil samples were mainly from high temperature combustion of coal,which is one of the industrial fossil fuels, the next is the traffic emission.PAHs of atmospheric deposition from the surrounding petrochemical industrial areas andresidential areas mainly came from combustion of coal, some sites were impacted byvehicle exhaust emissions, the pollutants of PAHs from the petrochemical industrialregion had affected the nearby residential areas. |
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