Shanghai Urban Fringe Area And Multi-scale Spatial Distribution Characteristics Of Soil Heavy Metal Pollution Evaluation

With the rapid development of urbanization andindustrialization,The urban fringe is constantly being citiesassimilated,The urban fringe has become the most sensitive areas of thecity,The environmental quality of urban fringe area has declinedmarkedly. The study of distribution and the evaluation of soil heavymetals in the city and the urban fringe can provide a theoretical basisto protect the city ecological environment and construct suitable livingenvironment in some sense. Soil heavy metals in minhang as a typicalurban fringe in Shanghai were analyzed to indicate the effect ofurbanization and industrialization on soil environment quality. Spatialvariation structure and distributions of5heavy metals (Cu, Cr, Mn,Pband Zn) in the top soil in minhang and its functional were analyzed,Thesoil heavy metals pollution was evaluated, obtaining main results asfollows:(1)The special distributions results of five soil heavy metal elements(Cu, Cr, Mn,Pb and Zn) in minhang showed that the special distributionsof soil Cu and Cr was multi-island shape distributed. the content of soilCu decreases from northwest to southeast but the distribution of soil Pbis relatively disorganized. Soil Cr, Mn was island-shape distributed,radiating decrease from the center to around. The spatial distribution ofSoil Zn showed the characteristics which combined of banded andisland-shape distribution.(2) Semi-variance analysis of soil heave metals in minhang showedthat the soil Mn agreed exponential model, soil Cu,Cr,Pb and Znsatisfied the linear model,and soil Cu,Pb and Zn showing purenugget.Show taken from the sampling density,Between the differentsampling sites showed strong independence and radomness,It reflectsthe complexity of the distribution strongly influenced by human activties and inerference of soil heavy metals in the urban fringe spacevariation,Also shows the current density of the sample does not reflectthe soil of Cu,Pb and Zn in the spatial structure,but also need for adetaied study in a smaller scale.(3)Analysis of heavy metal pollution in soil in minhang showed thatthe pollution of soil Zn,Pb,Cr is relatively serious,the single factor pollutionindex reached followed by1.25,1.22and1.19,belongs to the lightpollution, The exceeded rate of soil Cr, Zn and Pb reached50%or evenmore, while the exceeded rate of Cr was89%.In minhang theintegrated pollution index of87.2%of all greater than1,belongs to thelight pollution; the integrated pollution index of3.8%of all greater than2,pertaining moderate pollution.The light pollution is the main body of thedegree of pollution in minhang,followed by non-polluting,and themoderate pollution area is the meeting place of roads dense zone andindustrial park.(4) Semi-variance analysis in different functional areas showed thatthe soil Cu, and Zn agreed exponential model,the soil Cr and Mnagreed gaussian model,and the soil Pb agreed spherical model in theindustrial park;The soil Cu,Pb agreed gaussian model,and the soil Cr,Mnagreed exponential model,and the soil Zn agreed linear model inneighborhood;The soil Cu agreed linear model,the soil Pb agreedexponential model,and the soil Cr and Zn agreed spherical model inthe traffic green area;the soil Cu and Cr agreed exponential model,thesoil Mn,Pb and Zn agreed spherical in the park;the soil Cu,Cr,Pb and Znall agreed gaussian model,the soil Mn spherical model in agriculturalarea.Overall, the different functional areas of heavy metals in thesemi-variance function medel fitting better than minhang’s,thesampling of the different functional areas have been able to reflect thereflect the structurak features of the spatial variability of heavy metals.(5)Spatial variability struct?ures of heavy metal reflect different variation in different functional areas.The industrial zone of soil heavymetals of Cr and Mn space distribution is relatively simple,and the soil ofCu,Pb and Zn were island-shape distributed.In the neighborhood, parkand the agricultural area with the characteristics of combiningbanded,and aslo with the characteristics of combining island andbanded,like the soil Cu in the agricultural,Pb and Zn in the park andagricultural.Visible the industrial park where the heavy and lightindustrial distribution in,traffic-intensive areas,human activities intensiveare influence of soil heavy metals in the formation of this distributionstatus.(6)Various functional areas,Mn as a reference element,theenrichment factor of the different functional areas of soil heavy metalconcentrantion was found that the soil of Pb,Zn enriched moresignificantly,where soil Zn enrichment factor of the park is less than1,noenrichment, in the other four functional areas are slight enriched,andthe enrichment indexsequence of traffic green>industrial>agriculturearea>residential area,the soil Zn more significant enrichment in trafficgreen.The soil Pb is similar to soil Zn,the soil Pb enrichment factor of thepark is less than1,no enrichment,in the other four functional areas areslightly enriched,and the enriched indexsequence of the industrialzone>residential area>agricultural area>traffic green,the soil Pb moresignificant enrichment in the industrial zone.The soil Cu enrichment inthe industrial area than the other functional areas,the soil Cuenrichment in the industrial zone index of greater than1,is slightlyenriched,the soil Cu in the other four functional areas were less than1,isno enrichment,enrichment index in the order of the industrialzone>traffic green>agricultural area>park>neighorhood.(7)The scale of spatial structure analysis shows that the scale of thetransect and district level,the soil Mn has a significant spatialautocorrelation,spatial correlation of soil Cr was weak,the soil Cu,Pb,Zn in performance for the pure nugget coefficient;Under the scale ofindustrial zone level,the soil Cr has a strong spatial autocorrelation,thesoil Cu,Mn,Zn in a significant spatial autocorrelation,the soil Pb spacecorrelation is weak.Overall,with the narrowing of the research scale,thespatial correlation of siol heavy metals gradually increased.(8) In the scale study, spatial variability struct?ures of heavy metalreflect different variation. Heavy metals exist in a better spatial structurein the scale of industrial zone level;The spatial structure of three heavymetals (Cu, Pb and Zn) was pure nugget form, reflecting therandomness and independence without spatial continuity betweensamples,the structure of spatial variability of these three heavy metalscan not well be revealed in the scale of the transect and district level.The distribution of soil Cu, Pb, Zn were generally similar, with thecharacteristics of combining island and banded, and soil Cr, Mn wereisland-shape distributed in transect scale.In the district level,the soil Cuand Pb space distribution characteristics realizable for multi-island areadistribution,and the distribution of soil Pb was relatively disorganized;soilCr and Mn were general in banded structure,the distribution of soil Znwas with the characteristics of combining island and banded.In thescale of industrial zone level,the soil of Cr and Mn spatial disribution wasrelatively simple,the soil Cu,Pb and Zn were island-shapedistributed,which by its strong industrial processing and other humandisturbance.(9)Between the level of unbanization,pollution index and heavymetal single factor pollution index analysis showed that:there weresignificant positive correlation between soil Zn single factor pollutionindex,the integrated pollution index and the level of urbanization;Thesoil of Cu,Cr,Mn and Pb single factor pollution index and the level ofurbanization of the correlation coefficient for the correlation is notobvious;Between the level of urbanization index of the towns in minhang district and the towns of soil heavy metal pollution index theregression analysis showed that:Both soil Zn single factor pollution indexand the integrated pollution index with the composite indicator of thelevel of urbanization of the fitting curve showed the environmentalKuznets curve(EKC) feature,namely that soil heavy metalscontaminated with the improvement in the level of urbanization in thebeginning stages of urbanization will continue to deteriorate,but whenthe urbanization level reaches a certain level of soil heavy metals in theurban fringe soil pollution with raising the level of urbanization beimproved.