Distribution Of Polycyclic Aromatic Hydrocarbons And Black Carbon In The Topsoil Of Suburban Areas In Guanzhong

With the improvement of people's living standards in recent years,the acceleration of industrialization has brought convenience to people's lives,pollution problems have become more and more serious,and soil is a gathering place for various sources of pollution.As a result,polycyclic aromatic hydrocarbons and black carbon are increasingly attracting attention as persistent organics.In this paper,Xi'an is chosen as a research area to study the polycyclicaromatic hydrocarbons(PAHs)in the soil in depths(0-20cm)and depths(0-50cm)in the heating and non-heating areas of Xi'an City.The content and distribution characteristics reveal the composition of PAHs in different functional areas of Xi'an,the degree of pollution,the sources,the factors affecting the distribution of PAHs and the assessment of human health risks,and the PAHs,black carbon,and total organics.The correlation of carbon was analyzed,and the correlations between polycyclic aromatic hydrocarbons,black carbon,and total organic carbon in different functional areas were discussed to analyze the effects of black carbon and total organic carbon on polycyclic aromatic hydrocarbons.The main conclusions are as follows:(1)Polycyclic aromatic hydrocarbons(PAHs)are commonly found in the soil.The results show that the general trend of PAHs in soils with different functional areas is industrial>commercial area>road area>school>park>suburb>control area;concentration during heating period is greater than that in the non-heating period,the concentration of surface soil was greater than that of the non-warming period;source analysis showed that Ant/(Ant+Phe)(0.12-0.36)and Flu/(Flu+Pyr)(0.15-0.94)of the Xi'an surface layer.The source of PAHs in the soil is mainly the combustion source;Pyr/BaP indicates that the source of PAHs in industrial,suburban,and contrast areas is coal-fired and domestic pollution sources,and the source of PAHs in road,business,park,and school functional areas is the main source of pollution.For traffic pollution,it can be seen that the change of PAHs concentration in different functional areas is closely related to the pollution source.(2)The distribution of black carbon in soils with various functional areas is different.The value of black carbon in industrial and road areas is the highest,followed by commercial areas,schools,parks,and finally suburbs and comparison areas;the concentration of black carbon in heating periods is greater than that in non-heating period.The concentration of black carbon in surface soil is greater than that in the underlying soil.The distribution rule of organic carbon in the soil is highest in the suburbs of the controlied area,followed by parks,road areas and schools,and industrial areas.The concentration of organic carbon in commercial areas is the least.The concentration of organic carbon in the soil during heating is higher than that in the non-heating period.The concentration of organic carbon in the surface soil is greater than the concentration of organic carbon in the underlying soil,indicating the origin of black carbon and organic carbon.The difference is significant.Char/soot,the source of black carbon in the soil is the emission from coal-burning motor vehicles(3)The correlation results show that there are significant differences in the correlations between polycyclic aromatic hydrocarbons,black carbon and total organic carbon in different functional areas.From the perspective of different functional areas,the content of PAHs and PAHs in the suburban area and the controlled area,and the rings,and black carbon.Both(BC)and organic carbon were significantly correlated with R2=0.952(P<0.01);black carbon in industrial,commercial,and road areas was related to PAHs and PAHs,and organic carbon was only related to low rings.There was no correlation between polycyclic aromatic hydrocarbons and black carbon and total organic carbon in the parks and schools.It is obvious that black carbon has an indication of the degree of contamination of PAHs,and it is also an ideal carrier.(4)Calculate ILCRs under three different exposure pathways for children,youth,and adults in the surface soil of Xi'an City under normal circumstances.Since the respiration was relatively small compared to the other two exposure pathways,the largest female swallow was the female(0.81×10-6),the youngest male(0.58×10-6),and the youngest female who had the most skin contact.(0.93×10-6),the youngest is male(0.32×10-6).Different functional areas have different effects on children,youth,and adults.Industrial areas,commercial areas,and schools are all over 10-6,but all are below 10-5,and PAHs are commonly found in soils with different functional areas.The impact on the human body is not significant,however,as the sources of polycyclic aromatic hydrocarbons(PAHs)in the soil are complex,the PAHs generated by various substances will be most likely to be eventually transferred into the soil through various breakthroughs.Therefore,the impact of other factors should be taken into consideration.