Characteristics And Health Risk Assessment Of Heavy Metal Pollution In Road Soil In The Central Urban Area Of Yining,Xinjiang

Soil is an indispensable soil-forming factor in the ecological environment and a base f or the reproduction and production of individual organisms.It plays an irreplaceable role in the ecological cycle system.In particular,road soil habitat is extremely important for main taining road ecology and safeguarding human life.The complex traffic road network and r oad operation make the road in Yining city as the research object of road soil heavy metal pollution,which has important practical reference significance for the overall development of Yili road.In this paper,the systematic geographical theory and methods were applied to study the Yining city in western China as the target area,and soil samples were collected al ong nearly 25 roads in the core area of the city as the research object.Then,six elements（Hg,Cr,Ni,Pb,Cu and Zn）of mercury,chromium,nickel,lead,copper and zinc were analy zed.Firstly,Kriging interpolation was used to explore the current and spatial characteristic s of soil heavy metal pollution.Secondly,a series of indexes were used to evaluate the cum ulative level of soil pollution along the road.Finally,health risk assessment evaluation model was used to estimate the exposure dose of the population and then to esti mate the risk degree of the population from three exposure methods.In order to provide sci entific evidence for soil ecology,environmental monitoring and rational use of land resour ces.The following are the research conclusions of this paper:（1）Statistical and pollution characteristics of heavy metal elements in road soil0.11 mg·kg^-1,32.91 mg·kg^-1,34.68 mg·kg^-1,61.30 mg·kg^-1,31.35 mg·kg^-1,61.29 m g·kg^-1for expressway soil Hg,Cr,Ni,Pb,Cu and zinc average content of 6 elements in the study area soil Hg,Cr,Ni,Pb,Cu and zinc variation coefficient were 2.58,0.23,0.14,0.31,0.13 and 0.25,Hg variation than the rest of the elements is obvious,shows that Hg by som e local pollution is serious,Most likely,point source pollution is caused by human activitie s.The spatial characteristics of the other elements with stable changing format are more un iform.Hg,Cr,Ni,Pb,Cu and Zn were significantly different in distribution.On the whole,the elements in the road soil show as point source and surface pollution pattern.（2）Environmental quality assessment of heavy metal elements in road soilThe P_iof Hg,Cr,Ni,Pb,Cu and Zn in the study area were 0.809,0.613,1.486,2.568,1.515 and 0.898,respectively.P_Nof all 6 elements was greater than1,63.5%of Soil element P_Nin road area was greater than 2,indicating that soil along the road had different levels of pollution.The mean PLI of the six elements was 1.14,showing a slight trend.From the pe rspective of single pollution,Pb presented a moderate state,followed by Ni and Cu present-ed a mild state,Hg and Zn were under the warning line,and Cr presented a safety state.T he results showed that the pollution degree of elements in the soil was mild.The results of correlation analysis showed that Hg was not correlated with the other fi ve elements,indicating that Hg in urban road soil was correlated with its own geographical behavior,and there was no necessary relationship between elements and no similarity.At t he level of 0.01 confidence,all Pearson coefficients except Cr-Ni were lower than 0.6,indi cating a medium correlation.A variety of elements exist at the same time to change their o wn form and content changes.（3）Population exposure estimation and health risk assessment of peopleThe exposure（ADD）of the population through three ways of exposure from high to l ow is Pb>Zn>Cu>Cr>Ni>Hg,and the exposure dose of adults and children in three ways from large to small is hand-oral ingestion（ing）>skin surface contact（derm）>respir atory inhalation（inh）.The contents of 6 elements in soil were higher in children than in ad ults,and the difference was not significant.HQ_iof adults was HQ_ing>HQ_derm>HQ_inh.The HQ_iof children was HQ_derm>HQ_ing>HQ_inh.The adult HQ_iindex of six elements was Pb>Cr>Ni>Cu>Hg>Zn.The childre n’s HQ_iis from large to small:Hg>Cr>Ni>Cu>Pb>Zn.Overall,adult single HQ_iand no carcinogenic total risk index（HI）are less than 1,children with respiratory inhalation by hand-mouth intake of HQ_iless than 1,the performance is less risky and can ignore the ris k of cancer,the cancer risk is much higher than adults,children have suggested that childre n with urban road soil elements HI is higher,and heavy metals not obvious influence on ad ults’HI.From the point of view of CR index,Cr of adults is CR_ing>CR_inh>CR_dermand Ni is CR_ing>CR_derm>CR_inh.For children was CR_derm>CR_ing>CR_inh.Ni and Cr were the two el ements in the soil for CR_iin the population from large to small.In general,CR_iindex of ch ildren in urban road soil was higher than that of adults in three ways.Overall,the CR_iinde x and TCR index of the two elements in the soil were both lower than 1,and the CR_iindex of children was higher than that of adults,indicating that the health risk of children in the s oil elements of urban roads was high,and the health risk of adults was not obvious.